Appendix 10 Systematic review of herbal immunomodulators
From a systematic review of the literature, Spelman et al.1 have identified a number of herbs as having their action through modulation of one or more cytokines. While some herbs were shown to stimulate pro-inflammatory cytokine secretion, other herbs had suppressive actions on these cytokines. Some herbs were shown to do both, depending on dosage, cell type and type of stimulus. It is important to know the context of the cells or animals used in order to know how results of in vitro, ex vivo (stimulation of cells to secrete cytokines after blood has been taken) and in vivo cytokine studies should be interpreted.
A case in point is that Echinacea purpurea was shown to stimulate pro-inflammatory cytokine production, in a manner comparable to lipopolysaccharides (Echinacea increased levels of IL-10, TNF-α, IL-1β and IL-6 (p < 0.05) more than culture medium alone).238 While this may be desirable in the early stages of a respiratory tract infection in order to hasten the cell-mediated response to an infection, it may not be desirable in an individual with an overactive cell mediated response.
It would appear from this study that Echinacea may be contraindicated in chronic inflammation. However, based on this one study, this conclusion would be quite premature. The human macrophages used for this in vitro study came from one 50-year-old female. Details of possible confounds for cytokine production, such as preexisting health concerns, atopic status, stress or inflammatory status or medication intake, were not given. Further, oestrogen levels are usually fluctuating widely at this time of life, and the presence of oestrogen receptors on macrophages may influence cytokine production. For this reason, most studies of cytokines exclude perimenopausal women, and many exclude women altogether. This finding can hardly be considered representative.
