Buffalo/Mna rats spontaneously develop FSGS and nephrotic syndrome as a result of an immune disorder. Similar to some humans with FSGS, the disease recurs after renal transplantation, suggesting the involvement of a circulating factor. Here, we tested the effect of several immunosuppressive treatments on these rats. Although corticosteroids, cyclosporin A, and anti-T cell receptor treatment reduced proteinuria, only the deoxyspergualin derivative LF15-0195 led to a rapid and complete normalization of proteinuria. Furthermore, this compound led to the regression of renal lesions during both the initial disease and posttransplantation recurrence. The frequency of splenic and peripheral CD4 ϩ CD25 ϩ FoxP3 ϩ T lymphocytes significantly increased with remission. Moreover, the transfer of purified LF15-0195-induced CD4 ϩ CD25 ϩ T cells to irradiated Buff/Mna rats significantly reduced their proteinuria compared with the transfer of untreated control cells, suggesting that LF15-0195 induces regulatory T cells that are able to induce regression of rat nephropathy. These data suggest that idiopathic nephrotic syndrome/FSGS disease can be regulated by cellular transfer, but how this regulation leads to the reorganization of the podocyte cytoskeleton remains to be determined.

Semaphorin 3F (SEMA3F) provides neuronal guidance cues via its ability to bind neuropilin 2 (NRP2) and Plexin A family molecules. Recent studies indicate that SEMA3F has biological effects in other cell types, however its mechanism(s) of function is poorly understood. Here, we analyze SEMA3F-NRP2 signaling responses in human endothelial, T cell and tumor cells using phosphokinase arrays, immunoprecipitation and Western blot analyses. Consistently, SEMA3F inhibits PI-3K and Akt activity, and responses are associated with the disruption of mTOR/rictor assembly and mTOR-dependent activation of the RhoA GTPase. We also find that the expression of vascular endothelial growth factor, as well as mTOR-inducible cellular activation responses and cytoskeleton stability are inhibited by SEMA3F-NRP2 interactions in vitro. In vivo, local and systemic overproduction of SEMA3F reduces tumor growth in NRP2-expressing xenografts. Taken together, SEMA3F regulates mTOR signaling in diverse human cell types, suggesting that it has broad therapeutic implications.

Cancer (INCA MDSCAN PRT-K15-136 grant), and the Regional Ligue Contre le Cancer 44. We thank the staff of the Humanized Rodent Platform and MicroPICell Cellular and Tissue Imaging

Key Points• Loss of DGKe in endothelial cells induces cell death, impairs angiogenic responses, and leads to an activated and prothrombotic phenotype.• DGKE silencing in resting endothelial cells does not affect complement activation at their surface.Atypical hemolytic uremic syndrome (aHUS) is classically described to result from a dysregulation of the complement alternative pathway, leading to glomerular endothelial cell (EC) damage and thrombosis. However, recent findings in families with aHUS of mutations in the DGKE gene, which is not an integral component of the complement cascade, led us to consider other pathophysiologic mechanisms for this disease. Here, we demonstrate that loss of DGK« expression/activity in EC induces an increase in ICAM-1 and tissue factor expression through the upregulation of p38-MAPK-mediated signals, thus highlighting a proinflammatory and prothrombotic phenotype of DGK«-deficient ECs. More interestingly, DGKE silencing also increases EC apoptosis and impairs EC migration and angiogenesis in vitro, suggesting that DGKE loss-of-function mutations impair EC repair and angiogenesis in vivo. Conversely, DGKE knockdown moderately decreases the expression of the complement inhibitory protein MCP on quiescent EC, but does not induce complement deposition on their surface in vitro. Collectively, our data strongly suggest that in DGKE-associated aHUS patients, thrombotic microangiopathy results from impaired EC proliferation and angiogenesis rather than complement-mediated EC lesions. Our study expands the current knowledge of aHUS mechanisms and has implications for the treatment of patients with isolated DGKE mutations. (Blood. 2015;125(6):1038-1046 IntroductionAtypical hemolytic uremic syndrome (aHUS) is a severe form of thrombotic microangiopathy (TMA) that affects primarily the kidney. It is characterized by the occurrence of endothelial damage and fibrin/ platelet thrombi in the kidney microvasculature, leading to its typical triad of hemolytic microangiopathic anemia, thrombocytopenia, and acute renal injury.1 aHUS has a poor prognosis, with a 2% to 10% mortality rate, and about two-thirds of patients progress toward end-stage renal disease, and there is a high risk of recurrence of the disease after kidney transplantation.2 Over the past decade, many studies have highlighted the central role of complement alternative pathway dysregulations in the development of aHUS. [3][4][5] Several mutations in genes encoding complement regulatory proteins (factor H, 6 MCP, 7 factor I, 8 thrombomodulin 9 ) or components of the alternative C3 convertase (C3, 10 factor B 11 ), as well as the presence of circulating inhibitory anti-factor H antibodies, 12 have been shown to predispose to the development of aHUS. It is currently assumed that complement alternative pathway activation triggered mainly by infection or pregnancy 13 leads to endothelial cell (EC) damage and TMA. These observations led to the development of complement-targeted therapies for the treatment of aHUS, 14 and eculizumab, a mo...