Direct crosstalk between mast cell-TNF and TNFR1-expressing endothelia mediates local tissue inflammation.

Kneilling M, Mailhammer R, Hültner L, Schönberger T, Fuchs K, Schaller M, Bukala D, Massberg S, Sander CA, Braumüller H, Eichner M, Maier KL, Hallmann R, Pichler BJ, Haubner R, Gawaz M, Pfeffer K, Biedermann T, Röcken M

Zusammenfassung

Signaling through tumor necrosis factor receptor 1 (TNFR1) controls bacterial infections and the induction of inflammatory Th1 cell-mediated autoimmune diseases. By dissecting Th1 cell-mediated delayed-type hypersensitivity responses (DTHRs) into single steps, we localized a central defect to the missing TNFR1 expression by endothelial cells (ECs). Adoptive transfer and mast cell knockin experiments into Kit(W)/Kit(W-v), TNF(-/-), and TNFR1(-/-) mice showed that the signaling defect exclusively affects mast cell-EC interactions but not T cells or antigen-presenting cells. As a consequence, TNFR1(-/-) mice had strongly reduced mRNA and protein expression of P-selectin, E-selectin, ICAM-1, and VCAM-1 during DTHR elicitation. In consequence, intravital fluorescence microscopy revealed up to 80% reduction of leukocyte rolling and firm adhesion in TNFR1(-/-) mice. As substitution of TNF(-/-) mice with TNF-producing mast cells fully restored DTHR in these mice, signaling of mast cell-derived TNF through TNFR1-expressing ECs is essential for the recruitment of leukocytes into sites of inflammation.