Purpose

Transplanted tissues are differentially susceptible to ischemia/reperfusion and rejection. Endothelial cells (EC) are active regulators of inflammation. But model EC may not adequately reflect the variation among EC from different vascular beds and different transplanted organs, in basal and inducible inflammatory phenotypes.

Methods

Primary human EC from aorta (HAEC), coronary artery (HCAEC), cardiac microvessel (HCMVEC), pulmonary artery (HPAEC), lung microvasculature (HLMVEC), liver sinusoids (HSEC), skin microvasculature (HDMVEC) and kidney glomerulus (HRGEC) were compared for expression of adhesion molecules and chemokines by Nanostring Human Immunology, multiparameter flow cytometry and 38-plex Luminex assay (n=2 donors, ≥3 replicates).

Results

Of 373 immune genes expressed by at least one EC type, >150 were differentially expressed (fold >1.5, p<0.05). Large and microvascular EC were most closely related based on vascular bed rather than tissue of origin. Microvascular EC had higher basal levels of many signaling molecules, and other genes showed restricted expression to one cell type, which were confirmed by flow cytometry, and Luminex cytokine assay.

Strikingly, expression patterns of TNFα and IL-1β (10ng/mL)-inducible genes predominantly clustered by EC type before stimulus. TNFα and IL-1β increased ICAM-1, VCAM-1 and E-selectin mRNA and protein, but there were differences in the magnitude and kinetics across cells and between stimuli. For example, HAEC exhibit the largest increase in VCAM-1 expression. HCAEC maintained E-selectin expression longest. HSEC fail to upregulate E-selectin and had modest upregulation of ICAM-1 and VCAM-1 compared with other EC.

Inducible chemokine patterns were divergent. Cardiac EC produced more fractalkine than other EC. HAEC and HPAEC produced the most IL-6 and G-CSF compared with microvessel EC from the same organs. HSEC did not increase fractalkine or GM-CSF unlike other EC. Significant RANTES transcript and protein secretion was induced by TNFα in all but aortic and coronary artery EC.

Conclusion

In summary, endothelial cells from different tissues and vascular beds exhibit variation that likely contributes to differential regulation of leukocyte trafficking. The restrained response of HSEC to TNFα and IL-1β may in part explain the relative resistance of the liver to alloimmune injury. Analysis of transcription factors expressed by this cell type may identify potential therapeutic targets to dampen inflammatory responses of endothelial cells in other organs.

CITATION INFORMATION: Valenzuela N. Endothelial Cell Heterogeneity Governs Basal and Inducible Inflammatory Responses Relevant to Allograft Injury Am J Transplant. 2017;17 (suppl 3).

« Back to 2018 American Transplant Congress