Figure 5. Inhibitory targeting of P2X7 purinoceptors on MCs leads to amelioration of colonic inflammation.

Kit^W-sh/W-sh MC-deficient mice reconstituted with P2x7^+/+, P2x7^−/− or caspase-1^−/− BM-derived MCs were applied to a TNBS-induced colitis model. (a) Body weight changes were monitored in TNBS-treated Kit^W-sh/W-sh mice reconstituted with P2x7^+/+ (closed squares; n=9), P2x7^−/− (open squares; n=7) or caspase-1^−/− (open triangles; n=4). BM-derived MCs were used for TNBS treatment, and P2x7^+/+ BM-derived MC-reconstituted Kit^W-sh/W-sh mice receiving EtOH served as controls (closed triangles; n=3). *P=0.0264 (two-tailed Student's t-test), **P=0.0058 (two-tailed Student's t-test). Data are shown as percentages of baseline weights and are means±s.e.m. (b) Representative images of haematoxylin and eosin staining are shown. Scale bars represents 100 μm. (c) Representative images of whole colons are shown. (d) Colon length was measured 4 days after TNBS administration. Data are shown as means±s.e.m. (n=3 for P2x7^+/+ EtOH, n=9 for P2x7^+/+TNBS, n=7 for P2x7^−/− TNBS), *P<0.001 (two-tailed Student's t-test). (e) Representative flow cytometric data of infiltrated neutrophils (CD11b⁺Gr-1^high) in the colon from three individual experiments. *P=0.00741, **P=0.0009 (two-tailed Student's t-test). Data are shown as means±s.e.m. (f) The percentage of CD63⁺ MCs in all c-kit⁺ FcεRIα⁺ MCs was determined with flow cytometry. Data are shown as means±s.e.m. (n=3–9), *P=0.007 (Welch's t-test), **P=0.0234 (Welch's t-test). (g) Colonic tissue sections from a healthy volunteer (HV) and from UC and CD patients were stained with 4′,6-diamidino-2-phenyl indole (blue), MC tryptase (red) and P2X7 (green). Scale bars, 100 μm. (h) Cells expressing both P2X7 and MC tryptase were counted in the fields of the tissue sections (four fields for each section). Data are means±s.e.m. (n=6).