Immunomodulatory Role of Neuroendothelial Cells in Kidney Health and Disease

Background: There is an unmet medical need for specific, mechanism-based therapies for lupus nephritis (LN), the major organ complication and cause of morbidity and mortality in patients with systemic lupus erythematosus (SLE). A newly discovered subtype of endothelial cells (EC), termed neuro-endothelial cells (NECs) in renal resistance arterioles, plays key roles in maintaining vascular health and immune balance. NEC localizations and functions are consistent with the vascular mechanisms in LN. Cytokine-like 1 (Cytl1) is the top NEC-specific secreted factor with anti-inflammatory properties. The present study aimed to test the hypothesis that NEC-derived Cytl1 controls the local peripheral tissue-specific immune response in LN. Methods: A comprehensive experimental approach used NEC-specific, AAV2-QUADYF—Cytl1 sh/mRNA-mediated genetic silencing and overexpression of Cytl1 in vivo in C57B6 and NZM.2328 LN mice, endothelial and immune cell cultures in vitro, a chemotaxis assay, and in vivo multiphoton microscopy (MPM) of the mouse kidney. Results: Intravital MPM imaging found multiple severe and segmental, sphincter-like vasoconstrictions along all resistance vessels, and marked reductions in blood flow in NEC-Cytl1 KD mice compared to NEC-WT. NEC-Cytl1 KD mice featured increased glomerular vascular permeability to plasma albumin, reduced capillary density, and increased glomerular homing of CD45+ immune cell (17±2.36 vs 5±0.73/glom, p<0.01, n=8) compared to NEC-WT. Mouse recombinant Cytl1 reduced chemoattractant (Ccl19) induced chemotaxis of immune cells freshly harvested from LN mice. NEC density and function were markedly reduced in a mouse model of LN. Cytl1 gene therapy in LN mice resulted in reduced cortical expression of inflammatory markers VCAM (4.37+/-0.4 vs 17.49+/-7.9, p<0.0001, n=8) and ICAM (26.32+/-3.6 vs 48.64+/- 4.1, p=0.001, n=8), reduced immune cell homing in glomeruli (14+/-2.3 vs 43+/-1.5, p<0.0001, n=8), and about 2-fold reduction in urine albumin to creatinine ratio 4 weeks after Cytl1 gene therapy compared to control. Conclusion: In summary, our studies identified novel Cytl1 mediated anti-inflammatory and vasoprotective molecular-level mechanisms of a new EC-subtype that are highly relevant to lupus and have therapeutic potential.