The immune suppressive functions of macrophages are impaired in patients with ulcerative colitis

Abstract

Chronic inflammation is the pathological feature of inflammatory bowel diseases (IBD), but its etiology is unknown. Macrophages are one of the major immune cell fractions in the colon. The objectives of this study are to characterize the immune regulatory functions of macrophages in the colon of patients with ulcerative colitis (UC). UC patients (n = 30) were recruited into this study. Colon lavage fluid (CLF) was collected. Macrophages are isolated from the cellular components of CLF. The immune suppressive functions of macrophages were assessed using immunological approaches. We observed that macrophages occupied about half of the proportions of the cellular components in CLF. Lower amounts of IL10 mRNA and proteins were detected in macrophages of the UC group than the normal control (NC) group. The expression of IL10 in CLF macrophages was positively correlated with the UC-associated cytokines, including tumor necrosis factor-α, interleukin (IL)-1β, IFN-γ, eosinophil-derived mediators, in CLF. The immune suppressive functions of CLF macrophages in UC patients were impaired. The inducibility of IL10 expression of UC M0 cells was defective as compared with NC M0 cells. Exposure to CpG restored the inducibility of IL10 expression in UC M0 cells, and gain the potential to acquire the immune suppressive functions. To sum up, the immune suppressive functions of UC macrophages are impaired. The inducibility of IL10 expression of M0 cells is impaired, which can be restored by the treatment with CpG.