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ACTH treatment promotes murine cardiac allograft acceptance.

ABSTRACT: Heart transplantation is the optimal therapy for patients with end-stage heart disease, but its long-term outcome remains inadequate. Recent studies have highlighted the importance of the melanocortin receptors (MCRs) in inflammation, but how MCRs regulate the balance between alloreactive T cells and Tregs, and whether they impact chronic heart transplant rejection, is unknown. Here, we found that Tregs express MC2R, and MC2R expression was highest among all MCRs by Tregs. Our data indicate that adrenocorticotropic hormone (ACTH), the sole ligand for MC2R, promoted the formation of Tregs by increasing the expression of IL-2Rα (CD25) in CD4+ T cells and activation of STAT5 in CD4+CD25+ T cells. ACTH treatment also improved the survival of heart allografts and increased the formation of Tregs in CD28KO mice. ACTH treatment synergized with the tolerogenic effect of CTLA-4-Ig, resulting in long-term survival of heart allografts and an increase in intragraft Tregs. ACTH administration also demonstrated higher prolongation of heart allograft survival in transgenic mouse recipients with both complete KO and conditional KO of PI3Kγ in T cells. Finally, ACTH treatment reduced chronic rejection markedly. These data demonstrate that ACTH treatment improved heart transplant outcomes, and this effect correlated with an increase in Tregs.

SUBMITTER: Zhao J

PROVIDER: S-EPMC8410061 | biostudies-literature | 2021 Jul

REPOSITORIES: biostudies-literature

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ACTH treatment promotes murine cardiac allograft acceptance.

Zhao Jing J Jiang Liwei L Uehara Mayuko M Banouni Naima N Al Dulaijan Basmah S BS Azzi Jamil J Ichimura Takaharu T Li Xiaofei X Jarolim Petr P Fiorina Paolo P Tullius Stefan G SG Madsen Joren C JC Kasinath Vivek V Abdi Reza R

JCI insight 20210708 13

Heart transplantation is the optimal therapy for patients with end-stage heart disease, but its long-term outcome remains inadequate. Recent studies have highlighted the importance of the melanocortin receptors (MCRs) in inflammation, but how MCRs regulate the balance between alloreactive T cells and Tregs, and whether they impact chronic heart transplant rejection, is unknown. Here, we found that Tregs express MC2R, and MC2R expression was highest among all MCRs by Tregs. Our data indicate that ...[more]

PMID: 34236047

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Project description:Acute and chronic rejection continue to represent serious challenges in transplant medicine. Current medical regimens focus on suppressing T-cell responses, lack effectiveness for some patients and impose significant risks of infection and malignancy. Recent studies have suggested that inhibition of co-stimulation pathways between antigen presenting cells (dendritic cells, macrophages, B-cells) and T-cells may serve as an effective strategy to prevent rejection by promoting allograft tolerance as opposed to simply suppressing immune responses. This concept has garnered excitement across the transplant community and demonstrated promising results in human renal transplant studies. A commonly used approach is inhibition of B7-CD28 and CD40-CD40L costimulatory pathways. Blocking these pathways leads to prolonged allograft survival in fully HLA-mismatched mouse heart transplantation models and non-human primates. There are important gaps in knowledge pertaining to mechanisms by which co-stimulation blockade modulates the recipient immune responses and confers donor organ tolerance. The precise immune cell populations and mechanisms responsible for induction and maintenance of donor organ tolerance remain incompletely understood. We have leveraged single cell RNA sequencing to dissect how traditional immunosuppression (cyclosporine) and co-stimulation blockade (CTLA-4 Ig, anti-CD40L neutralizing antibodies) differentially impact the immune landscape of the transplanted heart using a fully HLA-mismatched mouse model (Balb/c donor heart à B6 recipient). Analysis of these datasets demonstrated striking differences between these treatment regimens. Mice that received co-stimulation blockade displayed a marked increase in the abundance of classical dendritic cells (cDC1s and cDC2s). Compared to the cyclosporine treated group, these cells expressed negative regulators of T-cell stimulation including PDL1. Using recipient mice that lack either cDC1s or cDC2s, we found that cDC1s are absolutely required for co-stimulation blockade to confer long-term allograft survival and prevent recipient immune responses against the transplanted donor heart.

Project description:BackgroundLow levels of plasma adiponectin, an adipocytokine that possesses anti-inflammatory and antiatherogenic properties, frequently observed among obese subjects correlate with higher prevalence of several cardiovascular diseases. This study investigated whether adiponectin modulates allograft rejection in major histocompatibility complex class II-mismatched cardiac transplants.MethodsWe heterotopically transplanted Bm12 allografts into adiponectin-deficient (APN-/-, C57BL/6 background) or wild-type (APN+/+) mice. Some APN-/- mice received adiponectin reconstitution by adenovirus. Histologic analyses assessed allograft rejection, and real-time reverse-transcriptase polymerase chain reaction evaluated the genes for cytokines/chemokines associated with the immune and inflammatory responses. In addition, we tested the effect of adiponectin on proliferation and cytokine/chemokine production in mouse T lymphocytes stimulated in vitro with anti-CD3 antibodies.ResultsAllografts transplanted to APN-/- mice showed severe acute rejection relative to transplants in APN+/+ hosts accompanied by increased accumulation of CD4- and CD8-positive T lymphocytes and Mac3-positive macrophages. Adiponectin provision by adenovirus in APN-/- mice reversed these exacerbated responses to allografting. The rejected allografts in APN-/- mice contained significantly higher levels of tumor necrosis factor-alpha, interferon-gamma, and regulated on activation normal t expressed and presumably secreted. Moreover, adiponectin significantly suppressed proliferation and production of tumor necrosis factor-alpha, interferon-gamma, regulated on activation normal t expressed and presumably secreted, monocyte chemotactic protein-1, and interferon-gamma inducible protein-10 in mouse T lymphocytes stimulated in vitro with anti-CD3 antibodies.ConclusionsThese observations provide new mechanistic insight into immunoregulation in allograft recipients relative to obesity, an increasingly prevalent risk factor. Adiponectin may offer a new therapeutic target for allograft rejection after cardiac transplantation.

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ACTH treatment promotes murine cardiac allograft acceptance.

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ACTH treatment promotes murine cardiac allograft acceptance.

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