Dataset Information

The Immunological Basis of Liver Allograft Rejection.

ABSTRACT: Liver allograft rejection remains a significant cause of morbidity and graft failure in liver transplant recipients. Rejection is caused by the recognition of non-self donor alloantigens by recipient T-cells. Antigen recognition results in proliferation and activation of T-cells in lymphoid tissue before migration to the allograft. Activated T-cells have a variety of effector mechanisms including direct T-cell mediated damage to bile ducts, endothelium and hepatocytes and indirect effects through cytokine production and recruitment of tissue-destructive inflammatory cells. These effects explain the histological appearances of typical acute T-cell mediated rejection. In addition, donor specific antibodies, most typically against HLA antigens, may give rise to antibody-mediated rejection causing damage to the allograft primarily through endothelial injury. However, as an immune-privileged site there are several mechanisms in the liver capable of overcoming rejection and promoting tolerance to the graft, particularly in the context of recruitment of regulatory T-cells and promotors of an immunosuppressive environment. Indeed, around 20% of transplant recipients can be successfully weaned from immunosuppression. Hence, the host immunological response to the liver allograft is best regarded as a balance between rejection-promoting and tolerance-promoting factors. Understanding this balance provides insight into potential mechanisms for novel anti-rejection therapies.

SUBMITTER: Ronca V

PROVIDER: S-EPMC7492390 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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The Immunological Basis of Liver Allograft Rejection.

Ronca Vincenzo V Wootton Grace G Milani Chiara C Cain Owen O

Frontiers in immunology 20200902

Liver allograft rejection remains a significant cause of morbidity and graft failure in liver transplant recipients. Rejection is caused by the recognition of non-self donor alloantigens by recipient T-cells. Antigen recognition results in proliferation and activation of T-cells in lymphoid tissue before migration to the allograft. Activated T-cells have a variety of effector mechanisms including direct T-cell mediated damage to bile ducts, endothelium and hepatocytes and indirect effects throug ...[more]

PMID: 32983177

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Project description:Background: Acute T cell-mediated rejection (TCMR) is a common immunological feature in renal transplantation and is associated with reduced graft survival. However, the full immunological profiling of acute TCMR remains unknown. Methods: A fully mismatched acute TCMR model was induced by transplanting the left kidneys from BALB/c mice into C56BL/6J mice. Allografted kidneys were harvested on day 7 (D7) and sorted for CD45+ leukocytes for single cell RNA sequencing (scRNA-seq) . In addition, scRNA-seq data of CD45+ immune cells on day 15 (D15) containing GSE157292 dataset (samples GSM4761000 and GSM4761003) were downloaded from Gene Expression Omnibus. All data obtained from D7 and D15 were integrated and analyzed. Results: We identified 20 major immune cell types among 10921 immune cells, including macrophages, B cells, T cells, dendritic cells, natural killer cells, neutrophils, and basophils in kidney allografts. Macrophages and CD8 T cells constituted the main immune cell populations on both D7 and D15. In the process towards immune regression, the proportion of CD8 T cells dropped significantly by about 25%, mainly due to decreased proliferation and naïve CD8 T cell infiltration. The proportion of both B cells and neutrophils also decreased by about 3 folds. On the contrary, the relative proportion of macrophages and DCs increased significantly, especially by a 4 fold increase in Ly6cloMrc1+ resident macrophages A group of Ly6cloEar2+ macrophages also increased by about 3 folds. Moreover, myeloid cells harbored the richest ligand and receptor (LR) pairs with other cell types, particularly for chemokine ligands such as Cxcl9, Cxcl10, Cxcl16 and Yars. However, macrophages with weak response to interferon gamma (IFNg) contributed to rejection regression. Conclusions: There is a comprehensive single-cell landscape of the kidney allograft immune cells from rejection progression to regression in acute TCMR. Reduction in CD8 T cells, B cells, and neutrophils while increasing in Ly6clo macrophages, including Ly6cloMrc1+ resident macrophages and Ly6cloEar2+ macrophages, may contribute significantly to immune rejection regression during acute TCMR.

Project description:OBJECTIVE:The immune rejection mediated by CD4+ T cell and antigen presenting macrophages is the leading cause of corneal transplantation failure. Bone marrow-derived mesenchymal stem cells (BM-MSCs) possess robust immunomodulatory potentials, and have been shown by us and others to promote corneal allograft survival. However, the immunological mechanism underlying the protective effects of BM-MSCs remains unclear. Therefore, in the current study, this mechanism was investigated in a BM-MSC-treated rat model of corneal allograft rejection, in the hope to facilitate the search for novel interventional targets to corneal allograft rejection. METHODS:Lewis rats were subjected to corneal transplantation and then received subconjunctival injections of BM-MSCs (2×106 cells / 100 μl PBS) immediately and at day 3 post-transplantation. The control group received the injections of PBS with the same volume. The clinical parameters of the corneal allografts, including opacity, edema, and neovascularization, were regularly evaluated after transplantation. On day 10 post-transplantation, the corneal allografts were collected and subjected to flow cytometry and high-throughput RNA sequencing (RNA-seq). GO enrichment and KEGG pathways were analyzed. The quantitative realtime PCR (qPCR) and immunohistochemistry (IHC) were employed to validate the expression of the selected target genes at transcript and protein levels, respectively. RESULTS:BM-MSC subconjunctival administration prolonged the corneal allograft survival, with reduced opacity, alleviated edema, and diminished neovascularization. Flow cytometry showed reduced CD4+ T cells and CD68+ macrophages as well as boosted regulatory T cells (Tregs) in the BM-MSC-treated corneal allografts as compared with the PBS-treated counterparts. Moreover, the RNA-seq and qPCR results demonstrated that the transcript abundance of Cytotoxic T-Lymphocyte Associated Protein 4 (Ctla4), Protein Tyrosine Phosphatase, Receptor Type C (Ptprc), and C-X-C Motif Chemokine Ligand 9 (Cxcl9) genes were increased in the allografts of BM-MSC group compared with PBS group; whereas the expression of Heat Shock Protein Family A (Hsp70) Member 8 (Hspa8) gene was downregulated. The expression of these genes was confirmed by IHC at protein level. CONCLUSION:Subconjunctival injections of BM-MSCs promoted corneal allograft survival, reduced CD4+ and CD68+ cell infiltration, and enriched Treg population in the allografts. The BM-MSC-induced upregulation of Ctla4, Ptprc, Cxcl9 genes and downregulation of Hspa8 gene might contribute to the protective effects of BM-MSCs and subserve the potential interventional targets to corneal allograft rejection.

Dataset Information

The Immunological Basis of Liver Allograft Rejection.

Publications

The Immunological Basis of Liver Allograft Rejection.

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