An in vitro model of antibody-mediated injury to glomerular endothelial cells: Upregulation of MHC class II and adhesion molecules

Abstract

Chronic active antibody-mediated rejection is a major cause of allograft failure in kidney transplantation. Microvascular inflammation and transplant glomerulopathy are defining pathologic features of chronic active antibody-mediated rejection and are associated with allograft failure. However, the mechanisms of leukocyte infiltration and glomerular endothelial cell injury remain unclear. We hypothesized MHC class II ligation on glomerular endothelial cells (GEnC) would result in upregulation of adhesion molecules and production of chemoattractants. A model of endothelial cell activation in the presence of antibodies to MHC classes I and II was used to determine the expression of adhesion molecules and chemokines. Murine GEnC were activated with IFNγ, which upregulated gene expression of β2-microglobulin (MHC class I), ICAM1, VCAM1, CCL2, CCL5, and IL-6. IFNγ stimulation of GEnC increased surface expression of MHC class I, MHC class II, ICAM1, and VCAM1. Incubation with antibodies directed at MHC class I or class II did not further enhance adhesion molecule expression. Multispectral imaging flow cytometry and confocal microscopy demonstrated MHC molecules co-localized with the adhesion molecules ICAM1 and VCAM1 on the GEnC surface. GEnC secretion of chemoattractants, CCL2 and CCL5, was increased by IFNγ stimulation. CCL2 production was further enhanced by incubation with sensitized plasma. Endothelial activation induces de novo expression of MHC class II molecules and increases surface expression of MHC class I, ICAM1 and VCAM1, which are all co-localized together. Maintaining the integrity and functionality of the glomerular endothelium is necessary to ensure survival of the allograft. IFNγ stimulation of GEnC

Macrophages in Transplantation: A Matter of Plasticity, Polarization, and Diversity

“…70 Intrarenal macrophages display a proinflammatory phenotype and secrete various cytokines including IFNγ, IL-1β, IL-12, IL-18, and TNFα, which can activate endothelial cells and promote cytotoxic T-cell generation. 71,72 Additionally, activated inflammatory macrophages can produce ROS and RNS that can aggravate allograft injury. 73 Taken together, these findings indicate injury of renal tubular epithelial cells promotes monocyte chemotaxis and upregulates costimulatory molecules on infiltrating monocytes during acute TCMR, which can facilitate T-cell activation and amplify TCMR (Figure 2).…”

Multiple Shades of Gray—Macrophages in Acute Allograft Rejection

“…As a result, the classically activated macrophages that predominate in the initial phase generate high amounts of ROS and reactive nitrogen species (RNS) [67] aggravating allograft injury and secrete pro-inflammatory cytokines such as IL-1β, IL-12, IL-18, TNFα and IFNγ [68][69][70][71][72]. This results in activation of endothelial cells and promotion of cytotoxic T-cell generation [73,74]. The pivotal role of macrophages during acute allograft rejection is not only suggested by the presence of macrophages in specimens showing acute cellular rejection [75] but also by transcriptome analyses of such biopsies.…”

B-cell Deficiency Attenuates Transplant Glomerulopathy in a Rat Model of Chronic Active Antibody-mediated Rejection

“…59,60 In agreement with clinical cohorts and mouse models of rejection in which increased IFNγ transcripts were present in rejection, [61][62][63] we found higher levels of IFNγ transcripts in the allogeneic and sensitized allogeneic groups compared with the B cell-deficient group in our rat model of cAMR. IFNγ enhances MHC expression on renal microvascular endothelial cells, 64,65 which increases antigen availability and, thus, contributes to the pathogenesis of cAMR (MVI and TG). In this model, the changes in histology were more extensive than the differences in renal function.…”