Genetic factors

In the immune system, cell surface protein molecules called human leukocyte antigens (HLA) recognise self from non-self. These antigens are unique for each individual and are encoded by a group of genes on the sixth chromosome called the major histocompatibility complex (MHC).⁵ On exposure to a foreign antigen, MHC antigens present a component of the invading antigen to circulating T-cells. MHC class I interact with cytotoxic T (CD8+) cells, which track down and kill specific cells, and MHC class II interact with helper T (CD4+) cells which, in the presence of pro-inflammatory cytokines, activate a full immune response (discussed further below under ‘T-cells’).⁶

Certain MHC class II genotypes are associated with increased susceptibility to autoimmune diseases. This susceptibility may be clustered within specific populations; for instance, increased risk of rheumatoid arthritis is associated with HLA-DR1 (in Asians, Spanish and Jewish Israeli nationals) and HLA-DR4 (in Caucasians).⁶

Some autoimmune diseases are associated with a single mutation, such as autoimmune lymphoproliferative syndrome. Importantly, not everyone that has the mutant gene manifests the disease. Of those that do, there is a wide variation in the progression and severity of the disease. This implies that there are other factors controlling and regulating the pathogenesis of autoimmune disease.⁷

Most autoimmune diseases involve a combination of several genetic mutations. The net effect of a combination of mutations may manifest as a pathological phenotype (that is, the way a genotype actually manifests in an individual), depending on the presence or absence of protective factors, both genetic and non-genetic.⁷

Certain HLA alleles are protective against autoimmune disease. Protective genes and susceptibility genes may both be present in an individual. The net effect of protective and susceptibility genes determine an individual’s genetic susceptibility to autoimmune diseases.⁸

Specific gene-environment interactions are increasingly being discovered as research into the human genome progresses.⁹ It is estimated that there may be as many as 20 mutations associated with autoimmune diseases; these mutations are expected to be fully elucidated over the next few years as a result of work on the human genome project.¹⁰ However, it is important to note that not all individuals bearing susceptibility genes actually manifest the disease conditions. Gene–gene and gene–environment interactions that may help our understanding of the pathogenesis of autoimmune disease are gradually being discovered.

Environmental factors such as diet and lifestyle may interact with genes to trigger, delay or prevent autoimmune diseases. While it is not possible to avoid our genotype, our phenotype is more malleable. How our genotype actually manifests takes account of environmental factors and how these factors interact with our genes. Environmental triggers and an individual’s reaction to these triggers may offer effective therapeutic intervention points for the prevention, delay or mitigation of autoimmune disease in genetically susceptible individuals.

Environmental factors

Viral and bacterial infections, certain chemicals and drugs and mechanical injury have been implicated as potential triggers of autoimmune diseases in susceptible humans and animals.^7,10,11 Two mechanisms that are widely accepted explanations of how an infection may cause autoimmunity are known as molecular mimicry and bystander activation

‘Molecular mimicry’ is the term given to the process of activation of autoreactive helper T (Th or CD4+) cells through cross-reactivity between foreign antigens and self antigens. The foreign antigen may so closely resemble a self antigen that the immune system, having reacted successfully to this foreign antigen, starts reacting to the self antigen as well.⁵ ‘Bystander activation’ refers to the spontaneous activation of local autoreactive Th cells as part of a coordinated inflammatory response, which may occur as a result of any threat to homeostasis (such as infection).¹²

Recent research has identified another potential mechanism whereby bacteria may elicit autoimmune pathology. A group of bacteria called superantigens, which includes streptococcal and staphylococcal exotoxins, seem to short-cut the usual immune mechanisms of presentation and directly trigger CD4 cells to launch a full inflammatory response. The result is an enormous release of pro-inflammatory cytokines from T-cells, especially tumour necrosis factor-alpha (TNF-α) and IL-2. Exposure to superantigens has been shown to drive the intense inflammatory responses that result in acute toxic shock or chronic inflammatory disease, such as rheumatic fever.⁵

Antigen triggers need not come from the external environment—they may be endogenous proteins. Endogenous proteins that have been implicated in the pathogenesis of rheumatoid arthritis include human cartilage glycoprotein 39, citrullinated protein and heavy-chain binding protein.¹³

Dietary antigens have also been implicated in the pathogenesis of autoimmune pathology, especially the gastrointestinal autoimmune diseases.¹⁴ For instance, cereal grains are known inducers of two autoimmune diseases (coeliac disease and dermatitis herpetiformis); removal of gluten from the diet ameliorates symptoms in these conditions. A process of molecular mimicry is strongly suspected in the pathophysiology of these conditions.¹⁵ An inflammatory environment in the intestine (from dietary antigens) is associated with increased permeability and increased frequency of potentially

pathogenic antigens crossing the intestinal epithelium and entering the internal environment (‘leaky gut syndrome’). This is mediated by IFN-γ and TNF-α, both altering the tight junctions between cells, while IFN-γ increases the uptake of proteins for transportation into the mucosal cells.¹⁶

Recent in vitro work has postulated a role for certain internal environmental conditions that may favour the recognition and binding of large numbers of autoantigens by antibodies. After transient exposure to protein destabilising (but not denaturing) conditions, such as low or high pH, high-salt environments and redox-reactive agents, a small percentage of autoantibodies become extremely autoreactive.¹⁷ High salt and its sequelae, widespread low-level metabolic acidity, are hallmarks of the Western diet and are suspected as having an involvement in many so-called modern lifestyle diseases.¹⁸

Whatever the environmental trigger, the process of antibody autoreactivity is mediated by cytokines, which turn on and off the signals for T-cells specific for self antigens.¹⁹ Thus, in the pathogenesis of autoimmunity, cytokine biology may provide the weakest link in the chain of events that result in pathology.¹¹

Inflammatory mechanisms

The emerging paradigm in understanding T-helper cell subsets

The recent discovery of Th-17 cells uncovers a whole new arm of adaptive immunity, specific for inflammation and autoimmunity as illustrated in Figure 28.1.²⁴ A potent pro-inflammatory cytokine, IL-17, stimulates the production of TNF-α, IL-1β, IL-6, IL-8 and G-CSF (the colony-stimulating factor that increases neutrophils).²⁷

Figure 28.1 The emerging paradigm in understanding CD4+ (T helper) cell subsets, showing their respective differentiation and function.

Source: Mills 2008³²

Increased levels of Th17 cells have been found to be associated with both animal and human autoimmune diseases.^32–36 Many cytokines, such as IL-1, IL-6, IL-21, TNF-α, IL-23 and TGF-β, are known to stimulate IL-17 production from naive CD4+ T-cells in the presence of inflammatory stimuli such as toll-like receptors.³²

Low levels of TGF-β in the presence of IL-6 and IL-21, IL-1 and IL-23 appear to stimulate IL-17 while high levels of TGF-β suppress IL-17. IL-17 is regulated by TGF-β and IL-10 both directly and indirectly via conversion of naive T-cells into Treg cells.

Toll-like receptors are pattern-recognition receptors that have evolved to recognise specific bacteria and are found on many antigen-presenting cells, such as dendritic cells, in the innate immune system. When activated, toll-like receptors induce inflammation via activation of inflammatory transcription factors such as NF-kB, which up-regulate the production of pro-inflammatory cytokines, such as IL-17 from Th17 cells and IFG-γ from Th1 cells, as shown in Figure 28.2.

Figure 28.2 The role of Th17 in autoimmune pathology

Source: Mills 2008³²

Cytokines as the third signal

Recently, a ‘third signal’, provided by pro-inflammatory cytokines, has been postulated as a necessary requirement for full T-cell activation.³⁷ For instance, a soluble antigen injected into mice resulted in an increase in antigen-specific CD4+T-cells in lymph nodes and follicles. However, CD4+ cells activated in this way simply died off and did not react when re-exposed to the antigen. Although the CD4+ cells differentiated into antigen-specific T-cells in the first instance, when they received no further signal within a week after exposure to the antigen, they became hypo-responsive to the antigen on re-exposure.^37,38

While the T-cells may differentiate they do not necessarily make the transition into a long-term, sustained adaptive immune response, as characterised not only by the proliferation of antigen-specific T-cells, but by the transition to the cloning of specific helper T-cell subsets and memory cells, which in turn influence B cells to generate antigen-specific antibodies. If, on the other hand, bacteria are present during activation, there is a sustained increase in antigen-specific T-cell cloning, along with migration of T-cells to lymph regions rich in B cells, resulting in the stimulation of antigen-specific antibodies.

An important observation was made during these studies. It was noted that the effect of the bacteria was mediated by the secretion of the cytokine, IFN-γ, from T-cells.³⁹ More importantly, the enhanced effect on T-cell activation by the bacteria was replicated when the bacteria were altogether replaced by the pro-inflammatory cytokines, tumour necrosis factors and IL-1. In addition, the bacterial-induced IFN-γ was replicated by IL-12. Thus, successful activation of T-cells in vivo after exposure to an antigen requires the presence of certain pro-inflammatory cytokines even in the absence of bacteria or other infecting agent.³⁹

This ‘three-signal model’ has been further developed to specify IL-1 as the actual third signal for the antigen-induced activation of naive CD4+ T-cells, and IL-12 as that for CD8+ T-cells.³⁷ It has been proposed that the first two signals are adequate for a transient, localised response but that a long-term, sustained response depends on the presence of certain pro-inflammatory cytokines. IL-1 and TNF-α appear to have significant roles in the cytokine-driven longevity of antigen-specific memory T-cell populations.³⁸

Altered immune function

Ageing of the immune system has been associated with a decline of its ability to recognise self from non-self, thereby increasing the risk of the development of autoimmune diseases.⁴⁸ People with autoimmune diseases have immune systems that resemble those in the elderly, such as involution of the thymus, and premature ageing has been postulated as a risk factor for autoimmune disease.⁴⁹ On the other hand, young age is a risk factor for multiple sclerosis, with 70% of people with multiple sclerosis aged between 20 and 40 years.⁵⁰

Viruses have been shown in animal models to be potent triggers of autoimmunity through molecular mimicry and promoters of pathogenic responses through bystander activation. Humans with rheumatoid arthritis and SLE have an altered virus-specific response to the Epstein-Barr virus, for example. Of particular note, the virus-specific T-cells that drive autoimmune pathology appear to be directed by cytokines rather than by the virus itself.⁵¹ In genetically susceptible individuals, a combination of a latent Epstein-Barr viral load and altered immune regulation, for instance a functional deficit of Epstein-Barr virus-specific T-cells, may trigger rheumatoid arthritis and SLE.⁵² The occurrence of chronic recurrent infections is a known risk factor for rheumatoid arthritis.⁵³ A partial or complete deficiency in the complement proteins is a risk factor for SLE.^54,55 Immunodeficiency, for any reason (congenital or iatrogenic), increases the risk of non-Hodgkin lymphoma. Inflammatory diseases also increase the risk of non-Hodgkin lymphoma, with more severe inflammation increasing risk further.⁵⁶ Interestingly, a prospective cohort of 27,290 postmenopausal women found that NSAID use was associated with an increased risk of non-Hodgkin lymphoma.⁵⁷ It is likely that the NSAID use indicates an unresolved underlying inflammation, which is the actual risk factor for non-Hodgkin lymphoma.

Exposure to chemicals

There is conclusive evidence that smoking is a risk factor for rheumatoid arthritis.⁵⁸ There is also evidence that mercury from dental amalgam may increase the production of autoantibodies in mercury-sensitive patients with autoimmune thyroiditis.⁵⁹ Occupational and environmental exposure to asbestos and silica, respectively, increases the risk of developing an autoimmune disease.^60,61 Occupational exposure to mineral oil increased the risk of autoimmunity by 30%.⁵⁸ Epidemiological studies that have looked at vaccinations and exposure to environmental toxins have failed to show them as strong risk factors for autoimmunity, but because there is evidence for an association in animal and case-controlled studies there has been a call for more research in this area.^62,63

Diet and lifestyle

Many dietary and lifestyle factors may exacerbate autoimmune diseases. Early exposure to cow’s milk has been associated with increased risk of autoimmune diseases, especially type I diabetes.⁶⁴ Antigens from milk, grains and legumes have also been found to contain peptides that mimic those found in the joints of people with rheumatoid arthritis.¹⁵ Vitamin D deficiency is a risk factor for SLE and multiple sclerosis.⁶⁵ Dietary fatty acids is a possible risk factor in multiple sclerosis.⁶⁶ Sleep deprivation was shown to be a risk factor for disease in mice with a genetic susceptibility to develop SLE.⁶⁷ Ultraviolet radiation and geographic location are known risk factors for multiple sclerosis.⁶⁶

Hormones

Sex is a risk factor for autoimmune diseases. The prevalence of many autoimmune diseases, such as multiple sclerosis, rheumatoid arthritis and SLE, are higher in women than men. For instance, 90% of SLE cases occur in women.⁶⁸ On average, women experience their first symptoms of rheumatoid arthritis during menopause, around the time of the decline of ovarian oestrogens.⁶⁹ In a randomised controlled trial of hormone replacement therapy (HRT) in rheumatoid arthritis of 200 women, those that responded well to the HRT (they had significantly increased serum oestrogen levels) demonstrated improvements in disease symptoms and progression compared with controls.⁷⁰

Oestrogen appears to have a dual role in immune function, suppressing inflammation while stimulating antibody production.⁷¹ Oestrogen receptors have been found on cells from many different systems, including immune cells. In a mouse model of rheumatoid arthritis, when oestrogen receptors were blocked there was an earlier onset of the disease.⁷²

Phytoestrogens are very interesting compounds from plants and can produce mild oestrogenic activity in humans. One such example is quercetin from soybeans. It was demonstrated that quercetin could block antigen-specific Th 1 differentiation in neurons and ameliorate clinical severity and duration of disease in a mouse model of multiple sclerosis by binding to oestrogen receptors.⁷³ This suggests a potentially promising role for phytoestrogens in autoimmune disease.

Stress

Stress is a risk factor for many autoimmune diseases.^53,74,75 Stress is also known to worsen symptoms in many autoimmune diseases, particularly rheumatoid arthritis and multiple sclerosis.^76,77 Animal and human studies have linked defective neuroendocrine function with enhanced susceptibility of autoimmune diseases, such as rheumatoid arthritis, SLE, type 1 diabetes and Sjögren’s syndrome.^78–81 In animal models of autoimmune disease, the onset of the disease is associated with a lack of HPA axis responsiveness (see Section 5 on the endocrine system for discussion) to IL-1, where resistance to autoimmune pathology was maintained by normal HPA axis–immune system responsiveness.⁸²

Dietary modulation to reduce inflammation

In human evolution, there have been two major changes that have resulted in an increased consumption of grain (the agricultural and industrial revolutions) and have dramatically increased the availability of omega-6 rich vegetable oils.¹⁰⁰ Further, the domestication of livestock and poultry, with its associated decrease in omega-3-rich grass feeding and increase in omega-6 rich grain-supplemented feeding, resulted in a shift in the polyunsaturated compartment of animal products to higher levels of omega-6 fatty acids and lower levels of omega-3 fatty acids.¹⁰¹ During the 1960s the epidemic in coronary heart disease was attributed to the increased consumption of saturated fatty acids from animal products. High cholesterol was identified as a risk factor and every attempt was made to reduce cholesterol.¹⁰² There was a public health campaign that declared a ‘war on fat’. All Australians were urged to reduce fat consumption or at least to replace saturated fats with omega-6 rich polyunsaturated fatty acids, such as that from readily available vegetable oils.

Margarine was produced from vegetable oil by the partial hydrogenation of the omega-6 rich linoleic acid, which conveniently increased shelf life. The fact that commercial hydrogenation produced trans-isomers in the fatty acid molecule that are rarely found in nature was not considered relevant by manufacturers or health regulators at the time. Trans-fatty acids were cheap, easily added to pre-packaged foods and were not yet associated with heart disease, so they were ideal replacements for butter and lard.

The focus on reducing cholesterol by reducing dietary fat intake led to a new market range of ‘low-fat’ products. Natural products such as yoghurt were stripped of their fat content, which was replaced by a whole new range of synthetic additives, usually carbohydrate based. But this new Western diet, the combination of low fat and high carbohydrate intakes, over time has fed an epidemic of obesity and diabetes and the incidence of autoimmune diseases, especially type 1 diabetes, is rapidly rising.¹⁰³

Carbohydrate intake in the Western diet is much higher than that of most traditional diets and there is a compelling argument that the modern high-carbohydrate diet is associated with negative health outcomes, including increased risk of various autoimmune diseases.¹⁵ Grains may contain antinutrients, such as lectins, which not only reduce the absorption of micronutrients from the small intestine but have been shown to induce intestinal secretion of IFN-γ and up-regulate MHC class II expression in enterocytes, thereby exacerbating inflammation in coeliac disease.¹⁰⁴ The wheat protein gliadin was shown to inappropriately up-regulate MHC class II presentation in the presence of IFN-γ in inflammatory bowel disease.¹⁰⁵ Several gliadins are suspected of

molecular mimicry. Certain self-proteins, such as alpha-gliadin and the autoantigen BM 180, which has been isolated from the basement membrane of affected exocrine glands in Sjögren’s syndrome, share an almost identical amino acid sequence.¹⁵

Low levels of omega-3 intake, together with a high level of omega-6 intakes, creates an imbalance between n-6 and n-3 fatty acids that has been related to many modern-day diseases, from mental health problems to chronic inflammation and autoimmune disease. For instance, in habitually violent and impulsive male offenders with antisocial personality, plasma phospholipid DHA levels were significantly lower than controls, while the arachidonic acid metabolites PGE₂ and TXB₂ levels were elevated.¹⁰⁶ The raised level of arachidonic acid metabolites are evidence that the inflammatory pathways related to NF-κB and COX-2 have been activated, the former stimulating the up-regulation of the expression and activity of genes that code for the pro-inflammatory cytokines. According to one study,¹⁰⁷ the Palaeolithic diet consisted of an equal ratio of omega-6 and omega-3 fatty acids. This ratio is currently estimated at 10–15:1 in Australia, and 20–30:1 in the USA. The correction of the imbalance between the essential fatty acids has major clinical implications. For instance, the author of this study states that inflammation was reduced in patients with rheumatoid arthritis by reducing the ratio of n-6 to n-3 fatty acids to 2–3:1.

In broader evolutionary terms, the last century or two is an incredibly short period of time. While human protein-coding genes have not significantly changed, there has been a significant and dramatic change in our diet, corresponding with the rise of ‘lifestyle’ diseases such as chronic stress, heart disease, cancer, obesity, diabetes, depression and autoimmune diseases. Chronic inflammatory processes form an underlying component of all these diseases. Evidence is mounting that the modern Western diet, characterised by high caloric intake and high intake of carbohydrates, saturated, trans– and omega-6 fatty acids, and low intakes of antioxidants and omega-3 fatty acids in addition to an imbalanced omega-6:omega-3 fatty acid ratio, is a pro-inflammatory diet.

Early work in nutritional immunology showed that protein- and calorie-restricted diets were associated with dramatic and significant alterations in immune function, readily demonstrated in several animal models of autoimmune diseases.¹⁰⁸ In animal studies low-protein diets have delayed the onset of autoimmunity and blunted the clinical progression of autoimmune disease, and caloric restriction has more than doubled life span.¹⁰⁹ Protection from autoimmune disease by calorie restriction is thought to be associated with a reduction in T-cell proliferation and B-cell antigen formation when compared to a normal diet.¹¹⁰ Based on these findings, a 25–40% caloric reduction has been recommended as a safe and effective preventive strategy and treatment for autoimmune diseases in humans. This is, however, a huge undertaking for most people and requires an extraordinary commitment over a very long period of time.

Caloric restriction in combination with omega-3 fatty acids has been shown to both delay the onset and improve the progression of autoimmune diseases. A proposed mechanism for omega-3 fatty acids is through up-regulation of protective antioxidant pathways, resulting in lower oxidative stress and reduced pro-inflammatory cytokine expression and activity.

Omega-3 fatty acids and the inflammatory cascade

Omega-3 fatty acids influence the production of inflammatory metabolites from the omega-6 polyunsaturated fatty acid, arachidonic acid. For instance, leukotriene B₄ (LTB₄) is derived from arachidonic acid and is a potent stimulator of pro-inflammatory cytokine production.¹¹¹ One mechanism that EPA uses to suppress pro-inflammatory cytokine production is via the suppression of the production of LTB₄.¹¹² Recently, the long-chain fatty acids have been shown to directly activate gene-transcription factors responsible for the regulation of gene expression and activity for cytokines, such as NF-κB and peroxisome proliferator activated receptors, respectively.

As a general rule omega-6 fatty acids promote while omega-3 fatty acids inhibit the expression, production and secretion, and target cell responsiveness, of pro-inflammatory cytokines, as illustrated in Figure 28.3.¹¹³ When high levels of omega-6 fatty acids are present, however, the enzyme shifts its preference to favour omega-6 fatty acid metabolism.¹¹⁴ This means that diets rich in omega-6 fatty acids reduce omega-3 metabolism while promoting the production of arachidonic acid derived eicosanoids.¹¹⁵ Conversely, fish oil has also been shown to decrease the enzyme activity, suggesting the possibility of antagonistic inhibition of omega-6 metabolism by high levels of omega-3 fatty acids.¹¹⁶ This has particular implications for vegetarians that rely on land-based omega-3 fatty acids.

Figure 28.3 The metabolic pathways of the essential fatty acids showing the enzymatic competition for the desaturases and elongases and common food sources. Sunflower oil and most vegetable oils are rich in alpha-lipoic acid, while evening primrose oil capsules are rich in GLA, which is quickly metabolised into dGLA, a precursor for the anti-inflammatory PGE₁ eicosanoids.

Vegetarians and vegans rely heavily on the activity of these liver enzymes for the production of the long chain omega-3 fatty acids, as they do not consume them in their diet. Figure 28.4 illustrates some of the known influences on delta-6-desaturase. Essential cofactors include zinc, magnesium, niacin (vitamin B3), pyridoxine (vitamin B6) and vitamin C. The stress hormones, adrenaline, noradrenaline and cortisol, inhibit the enzyme as do high blood sugar levels and high levels of linoleic acid, as in the modern Western diet. DHA, as in those taking fish-oil supplements, also inhibits these enzymes, inhibiting the production of arachidonic-derived inflammatory mediators, such as prostaglandins and leukotrienes. The enzyme delta-6-desaturase is the rate-limiting step in eicosanoid synthesis (see Figure 28.4). The stress hormones cortisol and the catecholamines (adrenaline and noradrenaline) inhibit the enzyme. Dietary cofactors, such as zinc, magnesium, vitamins B3 and B6 and vitamin C, are also required for optimal enzyme functioning.

Figure 28.4 Rate-limited activity of delta-6-desaturase

Recently, the National Health and Medical Research Council (NHMRC) set targets for the daily intake of the long chain omega-3 fatty acids based on strong evidence of a protective effect from chronic disease at 610 mg for men and 430 mg for women (see the box below). In 2006, the Australian average intakes of omega-3 fatty acids were estimated from data collected during the 1995 National Nutrition Survey, taking into account the contribution of omega-3 fatty acids contained in red meat.¹¹⁷ The average estimate for Australians was 246 mg per day, but the median daily intake was only 121 mg per day.¹¹⁸ These data are alarming as they indicate that most Australians consume only about one-quarter of the daily requirements of these essential nutrients recommended for the prevention of chronic diseases.

In clinical trials, fish-oil supplements have shown beneficial outcomes in a range of autoimmune diseases. For instance, in a randomised, placebo-controlled, double-blind study of fish oil in systemic lupus erythematosus (SLE), 59 subjects were allocated into one of four groups. Subjects were given 3 × 1 g MaxEPA (180 mg EPA + 120 mg DHA) per day or 3 mg of copper (as copper di-glycinate amine acid complex) per day or both copper and fish oil or placebo (olive oil). The primary outcome measure was scores on the Systemic Lupus Activity Measure (SLAM-R), a routinely used, reliable and validated measure of disease activity. After 24 weeks of supplementation, participants in the fish-oil groups had significantly reduced scores on the SLAM-R (p < 0.05).¹¹⁹ This study demonstrated that symptoms of SLE improved significantly compared with placebo after 6 months of high doses of fish oil.

Physical exercise and the immune system

There appears to be many mechanisms by which exercise mediates beneficial effects on the immune system.¹⁴³ Perhaps the most interesting is that skeletal muscle acts as a storehouse of the branched-chain amino acids, which supply nitrogen for the synthesis of glutamine by skeletal muscle. Skeletal glutamine supplies the rest of the body with glutamine as a precursor for the antioxidant, glutathione.

Cells that rapidly proliferate, such as immune cells especially during inflammation, are highly dependent on skeletal glutamine release via muscle contractions during physical exercise. This has particular implications for autoimmune diabetes, as pancreatic beta cells have reduced expression and activity of glutathione, and rely heavily on a systemic supply. Skeletal muscles release glutamine into the bloodstream after physical exercise at a very high rate.¹⁴⁴ Muscle contractions during physical exercise thus may offset pancreatic β-cell glutamine depletion, and subsequent increase in glutathione levels and antioxidant protective mechanisms.

Depletion of glutamine may cause the immunosuppression often observed after significant stressors such as major surgery or excessive exercise. Patients undergoing major surgery (coronary, vascular and colon) that received glutamine supplementation had significantly lower postoperative infection rates.¹⁴⁵ Studies using the stress of elite athletics found that glutamine supplementation immediately after a race and again 2 hours after the race protected against the immunosuppression that often follows a race.¹⁴⁶ In those athletes that drank the glutamine beverage, 81% reported no upper respiratory tract infection episodes in the 7 days after the race, compared with those that had the placebo drink, which contained maltodextrin, where only 49% reported no upper respiratory tract infections.

Metabolic acidosis may precipitate glutamate depletion as it increases the utilisation of glutamine in the kidney. Stress, strenuous physical exercise, starvation and major surgery are associated with depletion of plasma glutamine.¹⁴⁷ The stress hormones cortisol and adrenaline are both associated with increased glutamine utilisation and depletion.

Physical exercise elicits a cytokine response in the body. The type of physical exercise is a determinant of the particular cytokine response. The take-home message is that moderate physical exercise has been shown to induce anti-inflammatory cytokines (IL-1 receptor antagonist and IL-10), and offers protection against inflammation and autoimmune diseases.¹⁴⁸

Psychological stress

Psychological and emotional stress increases the secretion of pro-inflammatory cytokines.^91,149–151 The clinical implications are that it is essential to address stress in order to effectively regulate cytokine biology. This may mean referral for counselling, meditation or relaxation training. Adaptogenic herbs and nutritional supplements are those that have been shown to be effective interventions in helping the organism cope with or adapt to stress. Botanical adaptogens and tonics that have received the most research attention include Panax ginseng, Eleutherococcus senticosus,^152–159 Withania somnifera,^160,161 Bacopa monnieri¹⁶² and Glycyrrhyza glabra¹⁶³ (see the endocrine and nervous system sections for more detail). A multivitamin and mineral supplement also improved several parameters of stress in a randomised, placebo-controlled, double-blinded clinical trial.¹⁶⁴ Lecithin has demonstrated adaptogenic qualities in rats.¹⁶⁵ Omega-3 fatty acids have also been shown to inhibit cytokine production.^111,166,167

Herbal medicine and inflammatory cytokines

Boswellia serrata has been used traditionally for treating a range of conditions, including inflammation. The anti-inflammatory agents in Boswellia serrata resin are the boswellic acids which have been shown to act as non-steroidal anti-inflammatory agents, inhibiting 5-lipoxygenase activity and thereby suppressing leukotriene production, such as the potent LTB4.^168–170 A systematic review of all randomised controlled trials (RCTs) of Boswellia serrata in inflammatory disease states has been published recently.¹⁷¹ This review found seven RCTs using Boswellia serrata in inflammatory conditions. Of these, three were for osteoarthritis of the knee and one was for rheumatoid arthritis. The review concluded that there was ‘encouraging but not compelling’ evidence for the use of Boswellia serrata for inflammatory conditions. Adverse effects reported in the clinical trials were mild and self-limiting, and included nausea, heartburn and gastrointestinal disturbances. Although the study of rheumatoid arthritis patients did not find any significant differences between groups, the Boswellia serrata group reduced their NSAID use more than did the placebo group.¹⁷² For more discussion on herbs in osteoarthritis of the knee, see Chapter 22 on osteoarthritis.

Indian trials in rheumatoid arthritis and CD demonstrated significant abatement of symptoms with administration of Boswellia serrata and, although the trials are difficult to obtain, they have been included in an Indian review of the literature.¹⁷³ The Indian review reported that in a series of clinical trials of moderate to severely affected patients with rheumatoid arthritis or aortic stenosis most (either bed-ridden or could not perform normal daily tasks) showed improvement in symptoms between 2 and 4 weeks of administration of Boswellia serrata extract.¹⁷⁴ When 17 patients were changed to the placebo, they all suffered re-onset of symptoms within 10 days.¹⁷³ Although it is not possible to fully evaluate the literature from a review, taken together these studies provide encouraging preliminary evidence for the use of Boswellia serrata as a potential intervention in autoimmune rheumatic conditions.

A note of caution: Boswellia serrata has been shown to inhibit in vitro all the major human drug detoxification enzymes, cytochrome P450 1A2/2C8/2C9/2C19/2D6 and 3A4 enzymes.¹⁷⁷ This has implications for herb–drug interactions, as these enzymes are involved in the metabolism of 95% of pharmaceutical drugs.¹⁷⁸ By inhibiting the metabolism of pharmaceuticals, Boswellia serrata may potentiate an overdose of other drugs. Until further research can clarify the clinical relevance of these interactions for therapeutic doses of Boswellia serrata, it may be best to avoid this herb in patients taking other medications.

Harpagophytum procumbens has been used traditionally for centuries to treat arthritic conditions, pain and a range of other conditions.¹⁷⁹ The extract from the roots is now a licensed medicine in Germany.¹⁸⁰ A thorough systematic review found there is good scientific evidence for the use of Harpagophytum procumbens in degenerative

joint diseases and other chronic inflammatory diseases.¹⁷⁹ The key actives are the iridoid glycosides, especially harpagoside; however, the level of pharmacological activity reportedly differs significantly depending on geographical location, extraction methods and the presence of other constituents that may be synergistic or antagonistic. For instance, harpagoside was shown to inhibit COX-2 expression comparable with ibuprofen but harpagide, another pharmacologically active compound found in the extract, was shown to significantly stimulate COX-2 activity by twofold.¹⁸⁰ Therefore, the anti-inflammatory activity of an extract may depend on the ratios of the pharmacologically active constituents. These variables have been postulated as an explanation for inconsistency across studies aiming to demonstrate anti-inflammatory activity of extracts.¹⁸⁰

The mechanism of action is not clear, but it has been shown to inhibit the secretion of the pro-inflammatory cytokines IL-1β and TNF-α, the pro-inflammatory enzymes COX-2 and iNOS, and other inflammatory mediators such as leukotriene C4, prostaglandin E2 and thromboxane B2.¹⁸¹ An open study in people with rheumatic conditions in the UK aimed to assess the safety and efficacy of 960 mg (480 mg twice daily) of Harpagophytum procumbens in 259 patients over 8 weeks.¹⁸² Significant improvements in global pain, stiffness and function were reported, and 66% of patients had reduced or stopped their pain medication by week 8.¹⁸² The treatment was considered safe and well tolerated, with no serious adverse events. While this study provides evidence for its safety, the methodology used does not allow conclusions to be drawn about the efficacy of the herb, as the placebo effect was not estimated by inclusion of a control group.

A word about the safety of use: it has been reported that Harpagophytum procumbens is contraindicated in people with gastric and duodenal ulcer and gallstones due to its bitter taste, which increases gastric acid secretion. This would make it contraindicated in Crohn’s disease and ulcerative colitis. As no data are available for pregnancy and lactation, it is best avoided during these times.¹⁸³ There is also some evidence that Harpagophytum procumbens may interact with anti-arrhythmic medications. In osteoarthritis studies, adverse effects were very mild gastrointestinal disturbances even at high doses (8100 mg) of extract. Most clinical trial dosages in osteoarthritis studies range from 960 mg to 2610 mg extract/day.¹⁸³

Uncaria tomentosa has been used for centuries in Peru to support immune function.¹⁸⁴ It is widely used as an anti-inflammatory herb and has been shown to significantly inhibit the activation of NF-kB,¹⁸⁵ and inhibit the stimulated production of TNF-α by 65–85%.¹⁸⁶ There are two species, Uncaria tomentosa and U. guianensis, which are used interchangeably in South America, but most Western preparations contain U. tomentosa due to its ease of standardisation.¹⁸⁷ In a study comparing the antioxidant and anti-inflammatory activity of the two species it was found that there were 35 times more alkaloids in U. tomentosa than in U. guianensis.¹⁸⁸ Interestingly, U. guianensis was the better antioxidant and stronger anti-inflammatory, challenging the widespread belief that oxindole alkaloids are responsible for its therapeutic actions. Others have identified the presence of quinic acids as having anti-inflammatory properties.¹⁸⁹ In a randomised, placebo-controlled, double-blinded study of freeze-dried U. tomentosa (1 capsule of 100 mg daily) in osteoarthritis of the knee, those taking the U. tomentosa had non-significant reductions in medically assessed osteoarthritis after 1 week of treatment that continued to become highly significant at the 2-week mark.¹⁹⁰ A review of the toxicology associated with oral administration of U. tomentosa noted that it had a low potential for acute toxicity.¹⁹¹

Curcuma longa and curcumin, the active constituent of C. longa, have demonstrated therapeutic effects in a wide range of autoimmune diseases.¹⁹² In a randomised, placebo-controlled double-blinded clinical trial of curcumin compared with placebo in 89 patients with quiescent ulcerative colitis, 2 g/day curcumin was significantly better than placebo at preventing remissions, and improving the clinical activity index and endoscopic index.⁸⁹ Curcumin has been described as a non-steroidal anti-inflammatory agent, and found to be twice as potent as the NSAID phenylbutazone during acute inflammation, but only half as powerful during chronic inflammation.¹⁹³ Curcumin was shown to inhibit the ex vivo stimulated production of pro-inflammatory cytokines TNF-α by 58% and IL-8 by 30%.¹⁹⁴

A study of 54 traditional Mexican Indian herbs found that only three were able to inhibit NF-kB, All belong to the Asteraceae family and are rich in sesquiterpene lactones.¹⁹⁵ Tanacetum parthenium contains high levels of the sesquiterpene lactone parthenolide, which has been shown to be anti-inflammatory by inhibiting the activation of NF-kB.^196,197 Urtica dioica has also been shown to be a potent inhibitor of NF-kB. A standardised extract used in Germany as a commercial drug preparation (IDS23, Rheuma-Hek) was shown to be effective as the inhibition of ex vivo TNF-α-induced NF-kB activation in human cells inhibits ikB degradation.¹⁹⁸ After oral administration of IDS23 for 7 and 21 days in 20 healthy volunteers, there was an inhibition in the ex vivo LPS stimulated TNF-α release of 14.6% and 24.0%, respectively, while IL-1β was inhibited by 19.2% and 39.3%, respectively.¹⁹⁹

The leaves of Tylophora indica have been used in Ayurvedic medicine for the treatment of respiratory disorders such as asthma. In a series of studies comparing the effects of Tylphora spp. and placebo in mice after contact sensitivity with a noxious agent, Tylphora spp. significantly and reproducibly prevented the onset of the delayed hypersensitivity response. Although cytokines were not measured, these studies demonstrated that the mechanism of action involved suppression of cellular (T-cell) immunity.²⁰⁰ For a review of studies into its effects in respiratory conditions see Chapter 6 on respiratory infections.

Hemidesmus indicus was shown to inhibit the ex vivo production of the pro-inflammatory cytokines TNF-α and IL-8 by 50%.¹⁹⁴ Anethole, a constituent of Foeniculum vulgare, has been shown to block TNF-α stimulated NF-kB activation.²⁰¹ In 14 renal patients with increased blood levels of TNF-α and reduced levels of IL-10, glomerular dysfunction and proteinuria, 900–1125 mg/day Ganoderma lucidum was shown to reduce TNF-α and increase IL-10 and correct renal dysfunction, including suppressing proteinuria.²⁰²

For a summary of a systematic review of herbal medicine on cytokines, see Appendix 2 at the end of the book.

Aetiology of SLE

Systemic lupus erythematosus (SLE) is a chronic inflammatory connective tissue disease that predominately affects women of childbearing age, although men and children may also be affected. Immunologically, there is impairment in T-cell function with abnormal cytokine production—specifically the over-expression of the pro-inflammatory cytokines IL-17, IFN-γ²⁰³ and TNF-α. Overproduction of IFN-γ has been linked with B-cell activation.²⁰⁴ Autoantibody production by activated B cells results in positive serum antinuclear antibodies, often anti-DNA antibodies.

Example treatment

The patient was advised to find out more about living with lupus from appropriate support groups. She was advised to become familiar with her own early symptoms and trigger factors in order to minimise future flares. For instance, sunlight exposure may induce flares, and she reports her skin feeling strange after exposure to sun. She was encouraged to find an indoor pool and continue her swimming. Physical activity is not only good for helping deal with stress and tension, but also helps to boost the immune system. She was also advised that her condition would not necessarily affect her ability to have a baby, although she was advised to stabilise her condition before trying to conceive.

Figure 28.5 Naturopathic treatment decision tree—autoimmune disease

Stress is a trigger factor for many people with lupus, so she was advised to consider stress management techniques and/or counselling. Stress management techniques will depend on the type of stress that she is experiencing, which needs to be thoroughly teased out, and a referral for a course of counselling may be advised (see the referral section). Yoga and meditation practices would be a great way to re-learn how to relax in the body, as yoga may help to strengthen muscles and meditation would help to calm the mind.

Dietary modifications were the primary intervention for the first consultation. The fatty acid profile in the background diet was manipulated in order to reduce production of arachidonic acid inflammatory metabolites and the pro-inflammatory cytokines. Herbal medicines were also prescribed to support her through the period of increased stress (Glycyrrhiza glabra) and also to help reduce the chronic inflammation (Boswellia serrata, Harpagophytum procumbens, Hemidesmus indicus and Uncaria tomentosa). The combination of herbs, diet and exercise would be assessed at another consultation, scheduled for 1 month’s time.

Counselling

The patient was referred for counselling for support in dealing with stress relating to her diagnosis and family planning issues. Strong emotions usually accompany such a diagnosis but must be managed as chronic stress and depression can lead to deterioration of the condition in terms of increasing inflammation and the risk of flares.²⁰⁵ Education about how to manage the disease, the medications and the role of emotions can help to cope with the diagnosis.²⁰⁶

Daily stress events have been shown to worsen symptoms of lupus more so than significant life events.²⁰⁷ The patient was counselled on new ways of dealing with daily stress and distress through these sessions.

A brief pain and stress management program incorporating biofeedback and cognitive behaviour therapy was significantly more effective than symptom monitoring (placebo) or usual care (no intervention controls) at reducing pain and physical symptoms in 92 SLE patients in an American randomised, placebo-controlled trial.²⁰⁸ Psychological functioning was improved in the active intervention group compared with placebo, while the usual care group (controls) actually deteriorated over time.

Physical exercise

The patient was recommended to think about getting fit on her own or getting a personal trainer to help her to develop an aerobic training program. In chronic inflammatory diseases, the conventional acute management strategy is to rest and medicate. However, in chronic diseases that wax and wane, it is important during times of remission to build muscle strength and increase range of motion.²⁰⁹ Exercise should start as low-impact and gradually increase. The specific type of exercise is not important; instead a range of types incorporating aerobic and anabolic should be encouraged. It should start with stretching and gradually be built up.

Most women with SLE suffer from poor quality of sleep, contributed to by corticosteroid use, lack of exercise and depressed mood.²¹⁰ A clinical trial of a supervised exercise program showed significant improvement in quality of life, depression and aerobic fitness in 60 women with SLE that participated in either the training group (60 minutes’ supervised training, three mornings per week for 12 weeks) or controls (did not participate in the training program).²¹¹ The training session consisted of 10 minutes warm-up and stretching, 40 minutes walking and 10 minutes of cooling down. There is good preliminary evidence that physical exercise can help in a range of symptoms associated with SLE.²¹² Exercise also improves mood outcomes.²¹³

Homoeopathy

In a Lancet published meta-analysis of homoeopathy in clinical trials there was an overall trend towards an effect for homoeopathy.²¹⁴ Many people with autoimmune diseases believe that homoeopathy may be helpful. In a survey of 413 people with inflammatory bowel disease, 52% had tried CAM, and homoeopathy was the most frequently used (55% of CAM users).²¹⁵ A survey of people with multiple sclerosis showed a similar trend.²¹⁶ Part of the reasons for the common use of homoeopathy seems to be dissatisfaction with conventional treatment and its side effects, and the fact that homoeopathy can be used alongside conventional medicine.²¹⁷

In a randomised, placebo-controlled trial of 112 patients using homoeopathy in rheumatoid arthritis, there were significant improvements in pain (18%) and articular index (24%) for both the placebo and active group. There was a huge drop-out rate in the 6-month study, causing some methodological issues. Most of the homoeopathic prescriptions were for Sulphur 30C and Rhus Tox 6C and 30C.²¹⁸ In an earlier, randomised, controlled trial using homoeopathy or placebo in rheumatoid arthritis in patients that were also using their own medication, those in the homoeopathy group had significant improvement in pain, articular index, stiffness and grip compared with the placebo group.²¹⁹

This body of research is promising and provides some preliminary evidence for an effect for homoeopathy. There is obviously a need for much more research into the efficacy of homoeopathy in autoimmune conditions. These conditions are complex and require multifaceted approaches. Perhaps there is a role for homoeopathy, which may one day be validated with much stronger evidence than we have today.

Expected outcomes and follow-up protocols

The diagnosis of a chronic autoimmune disease, such as SLE, can be a stressful and disempowering experience. Empowerment through education and self-help strategies has been shown to improve outcomes for people with SLE on a range of parameters including feelings of uncertainty, self-worth and depression.²²⁰ The major strategies that need to be monitored and continued are the stress management, the dietary modifications, the anti-inflammatory herbal intervention, the gradual build-up of aerobic fitness and the regular relaxation or meditation practice. Other activities that reduce stress and have beneficial outcomes on immune parameters should also be encouraged, such as laughter, meditation and activities such as choir singing and listening.

Most of the medications used to treat SLE involve a multitude of serious side effects that have to be monitored and minimised if possible. For instance NSAIDs are COX inhibitors, but cyclooygenase (COX) has two isoforms. The inhibition of COX-1 is associated with the serious side effects, particularly to the gut mucosa, causing nausea, and may lead to ulceration, which may be asymptomatic or may cause bleeding.⁸⁷ Some of these side effects are noted in the box above.²²¹ These effects may be minimised using slippery elm powder and probiotic supplementation. The traditional way is to take a teaspoon of slippery elm in yoghurt before breakfast.

During infection and inflammation, however, it is COX-2 that is substantially raised. COX-2 plays a key role in the mediation of inflammation in autoimmune diseases. Pro-inflammatory mediators are known to induce COX-2 and raise prostaglandin synthesis. It is COX-2 that the anti-inflammatory steroid hormones (the glucocorticoids) suppress. NSAIDs that selectively inhibit COX-2 inhibitors are just as effective as the traditional non-selective COX inhibitors, but without the serious side effects.⁸⁷ Further, small bowel permeability (‘leaky gut’) has been shown to be increased by the COX-1 inhibitors, but remains unaffected by COX-2 inhibitors.⁸⁷ Where possible, therefore, COX-2 inhibitors are the NSAID of choice.

A note of caution about COX-2 inhibitors is that the long-term use of certain COX-2 inhibitors is associated with increased risk of primary heart attacks and stroke (in people with no previous history of heart disease) and hence certain COX-2 drugs were withdrawn from the market in 2004–5.²²² Fortunately, it has been demonstrated that these complications can be reduced by combining fish-oil supplementation with COX-2 inhibitors.²²³

Lupus flares

Close management of flares should also be followed up. Has the patient experienced a flare since the last visit? What were the symptoms and what events preceded it? If it is possible (and it is not always) to identify the triggers of a flare, the triggers can be avoided in the future.

Many people with lupus experience periods when the symptoms return, or the disease ‘flares’ up. Indeed, 11% of all hospital admissions in the USA are due to SLE or lupus flares.²²⁴ What causes them is not clear. One study set out to see whether T-cell activation could predict them. In a 4-year follow-up study, 60 patients (57 females) with SLE were tested at baseline for a urinary marker of a T-cell proliferation (T-bet).²²⁵ By the 4-year mark 46.6% had experienced a flare; 28% were severe (organ involvement). Those with high urinary T-bet were eight times more likely to have a flare.

This study demonstrated that T-cell activation preceded a lupus flare. The T-cells were being activated long before the clinical manifestations appeared. This suggests that managing immune cell parameters to reduce the incidence of inflammation is of paramount

importance in attempting to prevent flares. The protocol outline above aims to reduce inflammation. During periods of increased inflammation, these protocol should be strictly adhered to.

It is an important aspect of each individual’s journey with lupus to identify the triggers that may combine to cause a flare. It may be useful to keep a journal for a while until some trigger factors become known. Most often they are lifestyle factors such as stress, infection, sunlight and some medications.²²⁶

The patient was advised to develop a strategy to deal with fatigue in order to minimise the risk of a flare. It is important to not get over-tired, to pay attention to the body signals and to rest often.²²⁶ It was advised that the patient start a yoga or meditation practice and instigate a discipline of practice for 1 hour every morning and 1 hour every evening. This may mean a major restructuring of the patient’s day and life to fit this in, but its importance must not be underestimated. The patient was also encouraged to build aerobic fitness by starting an exercise training program and building up to at least 30 minutes three times per week.

There is a known seasonal variation to lupus flares, with exposure to extremes of temperature best avoided to minimise the risk of flare.²²⁷ Sunlight exposure is another known trigger of flare and can be minimised by wearing protective clothing and sunscreen. The patient was advised to cover up when walking or jogging outside in summer and to go early in the morning or later in the afternoon to avoid the midday sun. Similarly, sunscreen should be used while swimming outside.

Reducing infections

Infections may be viral, bacterial, fungal or parasitic, and acute or chronic.²²⁸ Patients on immune-suppressive drugs and some patients with SLE are genetically more susceptible to opportunistic infections.²²⁹ Chronic infections such as hepatitis C should be closely monitored.

Periodontal disease and gum infections should be considered and carefully managed. Mouth ulcers should be dealt with immediately. They are generally taken as a sign that the immune system is struggling but if they do not respond within days to zinc and vitamin C treatment, teaspoons of medical honey and herbal antibacterial mouthwashes, they may be a sign of an underlying infection. In SLE, high temperature or fever is a warning sign of infection, which increases the risk of flare.

It has to be stressed that all infections should be treated immediately. See Chapter 6 on respiratory infections for advice on treating respiratory tract infections, and Chapter 27 for advice on urinary tract infections and the fungal infection, candida. Probiotics may need to be supplemented from time to time to ensure healthy bowel flora and help to prevent infections. If the patient does not respond quickly to herbal medicine treatment (within a few days), then medical treatment for antibiotics may be required to reduce the risk of endocarditis (inflammation of the heart valves).²³⁰ Sulfur antibiotics should be avoided as they are known to cause allergic reactions in 30% of SLE patients, and increase photosensitivity and skin rash.²³⁰

Infection in the SLE patient requires a much more rigorous approach than people without the disease. It may be prudent to refer early to a GP for antibiotics if a bacterial infection is suspected, as the consequences of an untreated infection can be devastating. The side effects of antibiotic therapy on the gut flora should be minimised by simultaneous supplementation with probiotics (see Section 1 on the gastrointestinal system). Every attempt should be made to avoid infection (see the box below for some ideas of prevention strategies).²³⁰

Pregnancy is known to trigger lupus flare in around 60% of women.^231,232 The patient was advised that, in women with stable SLE, pregnancy is safe for mother and child, although it does increase the risk of a flare.²³³ Pregnancy requires a management strategy commencing with an assessment of pre-gestational risk factors before conception. In most cases of a lupus flare during pregnancy, the disease can be successfully managed under medical supervision with a multidisciplinary approach.²³⁴ Hospitalisation may be required during the pregnancy. The miscarriage rate is about one in five in SLE, as opposed to one in 10 for normal pregnancies.²³⁵ The contraceptive pill, on the other hand, has been shown in a double-blind, randomised, placebo-controlled clinical trial of 183 women using the lupus flare as the end point to not trigger a flare.²³⁶

Stress and infections may exacerbate a flare-up of disease activity. It is important for prevention of a flare that people living with SLE take every precaution to minimise these and other environmental triggers that may lead to an increased risk of a flare. If the patient follows the above detailed prescription, her condition is expected to gradually improve over the course of weeks and months. Autoimmune conditions often wax and wane in presentation, so it is important to counsel the patient that, while progress may be being made, there is a likely chance of an exacerbation at some point. Although complete remission is the ultimate goal, a more modest outcome is the lessening of the severity of symptoms, a reduction in the frequency of flares and an overall enhancement of the person’s health and wellbeing.