Plasma concentrations of interleukin-1-beta, interleukin-6 and tumor necrosis factor-alpha, and of their soluble receptors and receptor antagonist in anorexia nervosa

Interleukin-1beta (IL-1beta), interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) induce anorexia, and multiple behavioral and biochemical alterations that mimic those of anorexia nervosa. Reports in the literature, however, contain contrasting data on the pattern of secretion of the three cytokines and on the downstream activities of their receptors and receptor antagonists in anorexia nervosa. We measured plasma concentrations of IL-1beta, IL-6, TNF-alpha, soluble IL-6 receptor (sIL-6-R), soluble TNF-alpha receptors I and II (s-TNF-alpha-R-I and II), and soluble IL-1beta receptor antagonist (s-IL-1beta-R-A) in 14 female patients with anorexia nervosa (nine restricters, five binge/purgers) and in 13 age- and sex-matched healthy control subjects to see whether the circulating cytokine concentrations and the downstream steps of cytokine activity were impaired, and if these alterations were correlated with some aspects of the disease. Concentrations of IL-1beta, IL-6, TNF-alpha, s-TNF-alpha-R-I and -II and sIL-1beta-RA in plasma did not differ significantly in patients with anorexia nervosa compared with control subjects. Concentrations of sIL-6-R were significantly lower in the patients than in the control subjects, but there were no differences between the two sub-types of anorexia nervosa. The etiopathogenetic significance of the sIL-6-R alteration is not clear, but together with recent data in the literature on cytokine function, the finding suggests that an impairment of the pro-inflammatory cytokine pathway might be involved in the development of anorexia nervosa.