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.