Cross‐presentation of dead‐cell‐associated antigens by DNGR‐1⁺ dendritic cells contributes to chronic allograft rejection in mice

The purpose of this study was to elucidate whether DC NK lectin group receptor-1 (DNGR-1)-dependent cross-presentation of dead-cell-associated antigens occurs after transplantation and contributes to CD8(+)T cell responses, chronic allograft rejection (CAR), and fibrosis. BALB/c or C57BL/6 hearts were heterotopically transplanted into WT, Clec9a(-/-), or Batf3(-/-)recipient C57BL/6 mice. Allografts were analyzed for cell infiltration, CD8(+)T cell activation, fibrogenesis, and CAR using immunohistochemistry, Western blot, qRT(2)-PCR, and flow cytometry. Allografts displayed infiltration by recipient DNGR-1(+)DCs, signs of CAR, and fibrosis. Allografts in Clec9a(-/-)recipients showed reduced CAR (p < 0.0001), fibrosis (P= 0.0137), CD8(+)cell infiltration (P < 0.0001), and effector cytokine levels compared to WT recipients. Batf3-deficiency greatly reduced DNGR-1(+)DC-infiltration, CAR (P < 0.0001), and fibrosis (P= 0.0382). CD8 cells infiltrating allografts of cytochrome C treated recipients, showed reduced production of CD8 effector cytokines (P < 0.05). Further, alloreactive CD8(+)T cell response in indirect pathway IFN-gamma ELISPOT was reduced in Clec9a(-/-)recipient mice (P= 0.0283). Blockade of DNGR-1 by antibody, similar to genetic elimination of the receptor, reduced CAR (P= 0.0003), fibrosis (P= 0.0273), infiltration of CD8(+)cells (p= 0.0006), and effector cytokine levels. DNGR-1-dependent alloantigen cross-presentation by DNGR-1(+)DCs induces alloreactive CD8(+)cells that induce CAR and fibrosis. Antibody against DNGR-1 can block this process and prevent CAR and fibrosis

Targeting the retinal microcirculation to treat diabetic sight problems

Diabetic retinopathy is a secondary complication of hyperglycemia caused by diabetes mellitus. The damage to the retina can ultimately cause vision loss as a result of increased capillary permeability and angiogenesis. Recent progress in the understanding of the mediators that drive angiogenesis, as well as the phenotypes of cells that are involved in this process, has provided a multitude of targets for pharmacologic intervention. This review presents the inhibitors of the biochemical processes that are at the root of diabetic retinopathy (i.e., non-enzymatic glycosylation of biomolecules, oxidative stress, activation of aldose reductase and activation of protein kinase C by formation of diacylglycerol) in addition to the inhibitors of the mechanical damage (i.e., increased vascular permeability, capillary occlusion and neovascularization

Dendritic cells control fibroblastic reticular network tension and lymph node expansion

© 2014 Macmillan Publishers Limited. All rights reservedAfter immunogenic challenge, infiltrating and dividing lymphocytes markedly increase lymph node cellularity, leading to organ expansion. Here we report that the physical elasticity of lymph nodes is maintained in part by podoplanin (PDPN) signalling in stromal fibroblastic reticular cells (FRCs) and its modulation by CLEC-2 expressed on dendritic cells. We show in mouse cells that PDPN induces actomyosin contractility in FRCs via activation of RhoA/C and downstream Rho-associated protein kinase (ROCK). Engagement by CLEC-2 causes PDPN clustering and rapidly uncouples PDPN from RhoA/C activation, relaxing the actomyosin cytoskeleton and permitting FRC stretching. Notably, administration of CLEC-2 protein to immunized mice augments lymph node expansion. In contrast, lymph node expansion is significantly constrained in mice selectively lacking CLEC-2 expression in dendritic cells. Thus, the same dendritic cells that initiate immunity by presenting antigens to T lymphocytes also initiate remodelling of lymph nodes by delivering CLEC-2 to FRCs. CLEC-2 modulation of PDPN signalling permits FRC network stretching and allows for the rapid lymph node expansion--driven by lymphocyte influx and proliferation--that is the critical hallmark of adaptive immunity.info:eu-repo/semantics/publishedVersio