Distinct expression of cell-cell and cell-matrix adhesion molecules on endothelial cells in human heart and lung transplants

Abstract

Background and methods: Intercellular reactions and cell-matrix interactions are mediated by a number of specific adhesion molecules. For the intravascular reactivity of leukocytes and thrombocytes the endothelial expression of adhesion ligand molecules is of main importance. This condition may be of special relevance for the organ-specific manifestation of immune reactions in heart and lung transplants. The question was investigated as to whether organ-specific differences exist on arterial, venous, and capillary endothelial lining cells in heart and lung transplants and whether this condition is modified during transplant rejection. Transplant biopsy specimens of 24 heart transplant recipients (n = 303) and lung transplant recipients who underwent retransplantation for rejection (n = 4), as well as normal heart (n = 7) and lung tissue (n = 4), were studied. Cell-cell adhesion molecules (intercellular adhesion molecule-1 (CD54) and -2; LFA-3; CD31; vascular cellular adhesion molecule-1; neural cellular adhesion molecule; E-/P-selectin; CD44) and cell-matrix adhesion molecules (very late antigen-1 through -6; CD51) were studied on cryostat sections by means of standard immunohistology.

Results: (1) Arterial, venous, and capilary endothelia in lung and heart tissue show a distinct pattern of cell-cell and cell-matrix adhesion molecules: capillary and venous endothelia are in contrast to arterioles negative for vascular cellular adhesion molecule-1 and P-selectin. Arterial endothelia of the lung, in contrast to veins and capillaries, express no receptors for laminin (very late antigen-2 and very late antigen-6). (2) With transplant rejection, an induction of a number of adhesion molecules was noted on all endothelial lining cells in heart and lung transplants (intercellular adhesion molecule-1[CD54], intercellular adhesion molecule-2, lymphocyte function antigen-3, very late antigen-2, and very late antigen-6). Capillaries of the lung, in contrast to heart capillaries, displayed no inducibility of vascular cellular adhesion molecule-1 and E-selectin. In heart transplants, differences between capillaries and arteriovenous endothelia were found for virus-like agent-2 and -3.

Conclusions: These results show a distinct expression of a both cell-cell and cell-matrix adhesion molecules on arterial, venous, and capillary endothelia of heart and lung transplants. This expression may influence the local regulation of leukocyte and thrombocyte adhesion during transplant rejection. Especially lung capillaries show a lack of inducibility for vascular cellular adhesion molecule-1 and E- and P-selectin required for the induction phase of leukocyte adhesion. This lack was not found in heart transplants. This observation may explain differences in intravascular adhesion and infiltration between vessel compartments in hearts and lungs and could be of relevance for therapeutic interventions to modify leukocyte and thrombocyte adhesion, as during transplant rejection and reperfusion damage.