To explore the role of Gpr15 in Th17 cell regulation during TNBS-induced colitis following cigarette smoke exposure, we performed flow cytometric analysis of peripheral blood mononuclear cells (PBMCs), mesenteric lymph node cells (MLNs), and colonic lamina propria mononuclear cells (LPMCs) (Supplementary Figs. 4-6). Here, GPR15 is linked to colitis.