γδ T cells exacerbate intestinal fibrosis in mice with experimental colitis via activation of the CD73-adenosine receptor-cyclic AMP signaling pathway

Figure 5 Increased cyclic AMP levels prevented intestinal fibrosis. A: Experimental scheme of 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced intestinal fibrosis model. Forskolin and SQ22536 were intraperitoneally injected twice weekly for 4 weeks after TNBS administration; B: The concentrations of cyclic AMP and ATP in the colon tissues. Normal colon tissues were used as the control (n = 3 in each group); C: Quantitative polymerase chain reaction analysis of the expression of CD73 gene and the 5’-nucleotidase activity of CD73 in each group. Normal colon tissues were used as the control (n = 3 in each group); D: Body weight changes in the mice treated with TNBS or TNBS + forskolin or TNBS + SQ22536 during the experimental period (n = 5); E: Disease activity index score evaluated in the mice treated with TNBS or TNBS + forskolin or TNBS + SQ22536 (n = 5); F: The representative image for hematoxylin and eosin, Masson staining and immunohistochemistry staining of TCR within colon tissues in the mice treated with TNBS or TNBS + forskolin or TNBS + SQ22536. Orange arrow indicated areas of immune cell infiltration. Scale bars: 100 μm or 50 μm; G: The concentrations of hydroxyproline levels in the serum in the mice treated with TNBS or TNBS + forskolin or TNBS + SQ22536 at week 14 (n = 3); H: The levels of hyaluronic acid, type IV collagen, laminin, and procollagen III in the serum at week 14 (n = 3). Data were presented as mean ± SD. ^aP < 0.05, ^bP < 0.01, ^cP < 0.001. TNBS: 2,4,6-trinitrobenzenesulfonic acid; FSK: Forskolin; cAMP: Cyclic AMP; NT5E: 5’-nucleotidase; DAI: Disease activity index; H&E: Hematoxylin and eosin; LN: Laminin; IV-C: Type IV collagen; PCIII: Procollagen III; HA: Hyaluronic acid.