Lymphocyte-derived interferon-gamma mediates ischemia-reperfusion-induced leukocyte and platelet adhesion in intestinal microcirculation

Abstract

Although previous studies have implicated lymphocytes in the gut microvascular and inflammatory responses to ischemia-reperfusion (I/R), the lymphocyte population and lymphocyte-derived products that mediate these responses have not been defined. Platelet and leukocyte adhesion was measured in intestinal postcapillary venules of wild-type (WT) mice and mice genetically deficient in either CD4+ T cells (CD4-/-), CD8+ T cells (CD8-/-), B cells (B cell-/-), or interferon-gamma (IFN-gamma-/-) subjected to 45 min of ischemia and 4 h of reperfusion. The I/R-induced platelet and leukocyte recruitment responses were also evaluated following adoptive transfer of WT splenocytes into CD4-/-, CD8-/-, B cell-/-, and IFN-gamma-/- mice. WT mice exposed to gut I/R exhibited significant increases in the adhesion of both platelets and leukocytes, compared with sham-WT mice. These blood cell adhesion responses to I/R were greatly attenuated in CD4-/-, CD8-/-, B cell-/-, and IFN-gamma-/- mice. Adoptive transfer of WT splenocytes restored the WT responses to I/R in all mutants except the B cell-/- mice. These findings implicate both T and B cells and lymphocyte-derived IFN-gamma as mediators of the proinflammatory and prothrombogenic phenotype assumed by intestinal microvessels after I/R.

Fig. 1.

Effects of gut ischemia-reperfusion (I/R) on leukocyte adhesion in intestinal venules of wild-type (WT-I/R), CD4+ T cell-deficient (CD4^−/−-I/R), CD8+ T cell-deficient (CD8^−/−-I/R), as well as CD4^−/− and CD8^−/− mice after adoptive transfer with WT splenocytes (spleno). The I/R-induced adhesion responses in WT-sham mice are also shown. *P < 0.05 compared with WT-sham mice, #P < 0.05 relative to WT-I/R mice, †P < 0.05 compared with corresponding mutant mouse without splenocyte transfer.

Fig. 2.

Effects of gut I/R on platelet adhesion in intestinal venules of WT-I/R, CD4^−/−-I/R, CD8^−/−-I/R, as well as CD4^−/− and CD8^−/− mice after adoptive transfer with WT splenocytes. The I/R-induced adhesion responses in WT-sham mice are also shown. *P < 0.05 compared with WT-sham mice, #P < 0.05 relative to WT-I/R mice, †P < 0.05 compared with corresponding mutant mouse without splenocyte transfer.

Fig. 3.

Role of B lymphocytes in gut I/R-induced recruitment of adherent leukocytes. The adhesion responses in venules of WT-sham and WT-I/R mice are compared with those observed in B cell-deficient (B cell^−/−) with or without adoptive transfer of splenocytes. *P < 0.05 compared with WT-sham mice, #P < 0.05 relative to WT-I/R mice.

Fig. 4.

Role of B lymphocytes in gut I/R-induced recruitment of adherent platelets. The adhesion responses in venules of WT-sham and WT-I/R mice are compared with those observed in B cell^−/− mice with or without adoptive transfer of splenocytes. *P < 0.05 compared with WT-sham mice, #P < 0.05 relative to WT-I/R mice.

Fig. 5.

Responses of leukocyte adhesion in intestinal venules after I/R in interferon-γ-deficient (IFN-γ^−/−) mice and in IFN-γ^−/− following adoptive transfer of WT splenocytes. *P < 0.05 compared with WT-sham mice, #P < 0.05 relative to WT-I/R mice, †P < 0.05 compared with IFN-γ^−/− mice without splenocyte transfer; ΦP = 0.07 compared with WT-I/R.

Fig. 6.

Responses of platelet adhesion in intestinal venules after I/R in IFN-γ-deficient (IFN-γ^−/−) mice and in IFN-γ^−/− following adoptive transfer of WT splenocytes. *P < 0.05 compared with WT-sham mice, #P < 0.05 relative to WT-I/R mice, †P < 0.05 compared with IFN-γ^−/− mice without splenocyte transfer. ΦP = 0.056 compared with WT-I/R.