CD40–CD40 Ligand Mediates the Recruitment of Leukocytes and Platelets in the Inflamed Murine Colon

Effects of DSS (vs H₂O) treatment (day 0–day 6) on the expression of CD40 in the vasculature of the proximal and distal colon in WT mice at day 6. Zero denotes no detectable expression. Data are presented as the mean ± SE. *Denotes statistical significance (P < .05) compared with corresponding control (H₂O).

Changes in the disease activity index (A) and body weight (%) (B) over the course of DSS (or H₂O) treatment in WT, CD40-deficient (CD40^−/−), and CD40L-deficient (CD40L^−/−) mice. Data are presented as the mean ± SE. *P < .05 vs H₂O, ^#P < .05 vs DSS.

Length of the resected colon (cm) at day 6 of DSS (or H₂O) treatment in WT, CD40-deficient (CD40^−/−), and CD40L-deficient (CD40L^−/−) mice. Data are presented as the mean ± SE. *P < .05 vs H₂O, ^#P < .05 vs DSS.

Blinded histologic assessment of colonic mucosa at day 6 of DSS (or H₂O) treatment in WT, CD40-deficient (CD40^−/−), and CD40L-deficient (CD40L^−/−) mice. Zero denotes no detectable response in H₂O-treated WT mice. The total histologic score was derived from the severity and extent of inflammation and crypt damage. For each mouse, 3 sections were analyzed (mean ± SE). * and ^# denote statistical significance (P < .05) compared with control and WT DSS-treated animals, respectively.

Histology (H&E staining; magnification ×100) of colonic samples taken at day 6 from WT animals receiving H₂O (control) or from WT, CD40^−/−, and CD40L^−/− mice receiving DSS in drinking water. Compared with the colon of control animals (A), the colon of WT DSS-treated mice (B) showed destruction of the bowel wall architecture with loss of the epithelial lining (arrowheads), vanished crypts, submucosal edema (asterisk), and dense cellular inflammation in all layers (arrows). Histologic specimens of CD40^−/− (C) and CD40L^−/− (D) mice exhibited an attenuated morphologic damage with only mild cellular infiltration (arrow).

Colonic myeloperoxidase (MPO) activity at day 6 in H₂O-treated WT mice and WT, CD40^−/−, and CD40L^−/− mice receiving DSS in drinking water from day 0–day 6. *P < .05 vs water, ^#P < .05 vs DSS.

Rolling platelets (A) and leukocytes (B) and firmly adherent platelets (C) and leukocytes (D) in postcapillary venules on day 6 of treatment with H₂O (WT control) or DSS in WT, CD40^−/−, and CD40L^−/− mice. The number of platelets bound to leukocytes (platelet–leukocyte interactions) and those bound directly to endothelium (platelet–endothelial interactions) are shown in A and C. The number of platelet-bearing and platelet-free rolling and adherent leukocytes are presented in B and D. *P < .05 relative to H₂O, ^#P < .05 relative to WT mice treated with DSS ^&P < .05 relative to CD40^−/−.