Abatacept in B7-1-positive proteinuric kidney disease.

Abatacept (cytotoxic T-lymphocyte-associated antigen 4-immunoglobulin fusion protein [CTLA-4-Ig]) is a costimulatory inhibitor that targets B7-1 (CD80). The present report describes five patients who had focal segmental glomerulosclerosis (FSGS) (four with recurrent FSGS after transplantation and one with primary FSGS) and proteinuria with B7-1 immunostaining of podocytes in kidney-biopsy specimens. Abatacept induced partial or complete remissions of proteinuria in these patients, suggesting that B7-1 may be a useful biomarker for the treatment of some glomerulopathies. Our data indicate that abatacept may stabilize ß1-integrin activation in podocytes and reduce proteinuria in patients with B7-1-positive glomerular disease.

Extensive podocyte loss triggers a rapid parietal epithelial cell response.

Damage to podocytes is a central pathomechanism of proteinuric kidney disease. However, it is not fully understood how podocyte injury evolves to progressive glomerulopathies such as FSGS or collapsing glomerulopathy. In particular, the role of parietal epithelial cells remains controversial. Here, we show that adriamycin induces DNA damage and podocyte lysis in mice without evidence of autophagy, endoplasmic reticulum stress, or necroptosis. After extensive podocyte loss, activated parietal cells mediated tuft re-epithelialization by two distinct mechanisms. In the majority of glomeruli, vacuolized parietal epithelial cells attached to denuded glomerular basement membrane and, occasionally, disengaged from the parietal basement membrane. Less frequently, parietal epithelial cells covered the denuded visceral basement membrane via formation of proliferative pseudocrescents. Notably, "visceralized" parietal epithelial cells did not express vascular endothelial growth factor but upregulated hypoxia-inducible factor 1 expression. The presence of visceralized parietal epithelial cells in sclerosing and collapsing lesions in a kidney biopsy from a patient with diabetes underscores the human relevance of our findings. In conclusion, repopulation of the glomerular tuft by parietal cells may represent a compensatory response to extensive podocyte loss. Our results suggest, however, that visceralized parietal epithelial cells cannot induce revascularization of the hyalinized tuft, resulting in hypoxic cell death and irreversible destruction of the glomerulus.

Prognostic value of immune cell infiltration, tertiary lymphoid structures and PD-L1 expression in Merkel cell carcinomas.

Merkel cell carcinoma (MCC) is an aggressive, virus-associated, neuroendocrine tumor of the skin mainly affecting immunocompromised patients. Higher intratumoral infiltration with CD3 and CD8 positive T-cells is associated with a better prognosis, highlighting the relevance of the immune system for MCC development and progression. In this study 21 primary MCCs were stained with immune cell markers including CD3, CD4, CD8, CD68, CD20, and S100. Furthermore, tumor-infiltrating neutrophils, tertiary lymphoid structures and PD-L1 expression were analyzed and correlated with overall and recurrence free survival. All MCCs were Merkel Cell Polyomavirus positive. Overall and recurrence-free survival did not correlate with intra- and peritumoral CD3 and CD8 T-cell infiltration. In addition, no significant association regarding prognosis was found for tumor-associated neutrophils, tumor-associated macrophages or PD-L1 positivity in MCCs. Interestingly, the presence of tertiary lymphoid structures (TLS) in the tumor microenvironment significantly correlated with recurrence-free survival (P=0.025). In addition, TLS were significantly associated with a higher CD8/CD4 ratio in the tumor periphery (P=0.032), but not in the center of the tumor (P > 0.999). These results demonstrate for the first time that TLS, easily assessed in paraffin-embedded tissue in the tumor periphery of MCCs, may be a valuable prognostic factor indicating prolonged recurrence free survival.