P025 - CYSTATHIONINE-GAMMA-LYASE REGULATES MACROPHAGE INTERLEUKIN-10 (IL-10) PRODUCTION IN COLITIS
(Room Poster Hall)
19 Jan 18
5:30 PM
-
7:00 PM
Tracks:
Clinical and Research Challenges
Background: Cystathionine-β-synthase (CBS) & cystathionine-γ-lyase (CSE), convert homocysteine into cysteine & produce H2S, an anti-inflammatory mediator. In rodent colitis models, CBS & CSE activity is elevated and inhibition or knockout of CSE worsens colitis & decreases levels of anti-inflammatory cytokine IL-10. IL-10 KO mice develop spontaneous colitis accompanied by homocysteinemia & decreased H2S production, which are reversed by IL-10 administration. However, the cellular source of CSE-dependent IL-10 production is unknown. We hypothesize that macrophage-derived CSE is critical for IL-10 production. Methods: Human colitis & normal colon specimens were collected. CSE knockout (CSE KO) mice and wild-type (WT) controls received either 7 days of colitis-inducer DSS (2% in drinking water) or vehicle. CSE & cell-type specific markers were evaluated in human/mouse colons by immunofluorescent microscopy & flow cytometry. Peritoneal macrophages from CSE KO & WT mice (N = 6) were isolated & treated with CSE inhibitor propargyl glycine (PAG), H2S donor NaHS or vehicle. IL-10 & β-actin expression levels were determined by qRT-PCR. Results: Confocal microscopy of colitis & normal human colon tissue localized CSE to cells of the lamina propria expressing CD45, a marker of hematopoietic cells. Colonic tissue from mice receiving either DSS or vehicle also showed CSE staining in the lamina propria co-localized with macrophage marker F4/80. Flow cytometry showed co-expression of CSE with F4/80 but not Treg marker FOXP3. Comparison of macrophages from CSE KO to WT mice revealed a 6-fold reduction of IL-10 mRNA. Further, treatment of macrophages from WT mice with PAG inhibited IL-10 expression compared to controls. Addition of NaHS did not alter CSE KO macrophage expression of IL-10. Conclusion: We demonstrate that in macrophages CSE & IL-10 expression are linked in an H2S-independent manner. This suggests that CSE regulates inflammation through both H2S & IL-10.