Interleukin-17 induces an atypical M2-like macrophage subpopulation that regulates intestinal inflammation.

Interleukin 17 (IL-17) is a pleiotropic cytokine that acts on both immune and non-immune cells and is generally implicated in inflammatory and autoimmune diseases. Although IL-17 as well as their source, mainly but not limited to Th17 cells, is also abundant in the inflamed intestine, the role of IL-17 in inflammatory bowel disease remains controversial. In the present study, by using IL-17 knockout (KO) mice, we investigated the role of IL-17 in colitis, with special focus on the macrophage subpopulations. Here we show that IL-17KO mice had increased susceptibility to DSS-induced colitis which was associated with decrease in expression of mRNAs implicated in M2 and/or wound healing macrophages, such as IL-10, IL-1 receptor antagonist, arginase 1, cyclooxygenase 2, and indoleamine 2,3-dioxygenase. Lamina propria leukocytes from inflamed colon of IL-17KO mice contained fewer CD11b+Ly6C+MHC Class II+ macrophages, which were derived, at least partly, from blood monocytes, as compared to those of WT mice. FACS-purified CD11b+ cells from WT mice, which were more abundant in Ly6C+MHC Class II+ cells, expressed increased levels of genes associated M2/wound healing macrophages and also M1/proinflammatory macrophages. Depletion of this population by topical administration of clodronate-liposome in the colon of WT mice resulted in the exacerbation of colitis. These results demonstrate that IL-17 confers protection against the development of severe colitis through the induction of an atypical M2-like macrophage subpopulation. Our findings reveal a previously unappreciated mechanism by which IL-17 exerts a protective function in colitis.

Association of CXC chemokine receptor type 4 expression and clinicopathologic features in human vulvar cancer.

OBJECTIVE: Although CXC chemokine receptor type 4 (CXCR4) is known to be expressed in various solid tumors and plays an integral role in cancer invasion and metastasis, expression of CXCR4 in human vulvar cancer has not yet been investigated. We examined distribution and expression of this chemokine receptor in specimens of invasive and noninvasive human vulvar neoplasms to elucidate its clinical significance. METHODS: Study patients were 38 consecutive patients (31 with primary vulvar cancers and 7 with intraepithelial neoplasms) treated at one of our hospitals. Sections of all specimens were evaluated for CXCR4 expression by means of immunohistochemistry. Relations between CXCR4 expression and clinicopathologic features including prognosis were investigated. RESULTS: None of the 7 vulvar intraepithelial lesions expressed CXCR4. Of the 31 invasive vulvar tumor samples examined, 19 (61%) stained positively for CXCR4; 15 (68%) of 22 squamous cell carcinomas and 2 (29%) of 7 Paget tumors were CXCR4 positive. The difference in expression between invasive cancers and intraepithelial neoplasms was significant (P = 0.003). FIGO (International Federation of Gynecology and Obstetrics) stage III-IV cancers, in comparison to FIGO stage I-II cancers, were more likely to be positive for CXCR4 (82% vs 50%, P = 0.08). In terms of disease-free survival, prognosis of cancers that expressed CXCR4 was poorer than that of CXCR4-negative cancers (P = 0.013), but in terms of disease-specific survival, prognosis did not differ significantly between CXCR4-positive and -negative cancers (P = 0.111). CONCLUSIONS: More than half of invasive squamous cell vulvar cancers can be expected to express CXCR4, and CXCR4 expression correlates with poor disease prognosis.