Many pro-inflammatory cytokines especially tumor necrotic factor alpha (TNFα), interleukin (IL)-1β, and IL-6 have crucial role in the pathogenesis of endometriosis. In this study, we investigated the immune-modulatory role of humanized anti-IL-6 receptor monoclonal antibodies in the treatment of endometriosis. This is a prospective, randomized, controlled, blinded study in which Sprague Dawley rats were used as animal model of endometriosis. Animals were randomly divided into two groups, a test group which received tocilizumab (Actemra; Roche, Switzerland) and a control group which received saline. Afterwards, a comparison was done between the eutopic and ectopic endometrium that was excised from both groups, histopathologically and immune-histochemically. Histopathologic assessment and immune-histochemical staining were performed using antibodies against IL-6. Tocilizumab significantly suppressed the volume of endometriotic lesions compared with non-treated rats (P = 0.006) and atrophied the ectopic endometrial-like epithelium (in 42.8% of treated rats vs 0% in the control group). Tocilizumab also decreased the anti-IL-6 receptor immune-histochemical staining intensity in ectopic endometrium (from non to +++ in the test group vs ++ or more in the control group), with no apparent difference in the eutopic one reflecting the down-regulation of IL-6-producing cells in ectopic endometriotic lesions. In rats with induced endometriosis, anti-IL-6 receptor monoclonal antibodies could offer a new horizon of usage of this immune-modulatory biologic drug, used in other autoimmune diseases, in treatment of endometriosis.
Keywords: Anti-IL-6; Endometriosis; Rat model.