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HLA class II antibodies induce necrotic cell death in human endothelial cells via a lysosomal membrane permeabilization-mediated pathway.

ABSTRACT: Antibody-mediated rejection (AMR) is the major cause of allograft loss after solid organ transplantation. Circulating donor-specific antibodies against human leukocyte antigen (HLA), in particular HLA class II antibodies are critical for the pathogenesis of AMR via interactions with endothelial cells (ECs). To investigate the effects of HLA class II antibody ligation to the graft endothelium, a model of HLA-DR antibody-dependent stimulation was utilized in primary human ECs. Antibody ligation of HLA class II molecules in interferon-?-treated ECs caused necrotic cell death without complement via a pathway that was independent of apoptosis and necroptosis. HLA-DR-mediated cell death was blocked by specific neutralization of antibody ligation with recombinant HLA class II protein and by lentiviral knockdown of HLA-DR in ECs. Importantly, HLA class II-mediated cytotoxicity was also induced by relevant native allele-specific antibodies from human allosera. Necrosis of ECs in response to HLA-DR ligation was mediated via hyperactivation of lysosomes, lysosomal membrane permeabilization (LMP), and release of cathepsins. Notably, LMP was caused by reorganization of the actin cytoskeleton. This was indicated by the finding that LMP and actin stress fiber formation by HLA-DR antibodies were both downregulated by the actin polymerization inhibitor cytochalasin D and inhibition of Rho GTPases, respectively. Finally, HLA-DR-dependent actin stress fiber formation and LMP led to mitochondrial stress, which was revealed by decreased mitochondrial membrane potential and generation of reactive oxygen species in ECs. Taken together, ligation of HLA class II antibodies to ECs induces necrotic cell death independent of apoptosis and necroptosis via a LMP-mediated pathway. These findings may enable novel therapeutic approaches for the treatment of AMR in solid organ transplantation.

SUBMITTER: Aljabri A

PROVIDER: S-EPMC6408495 | biostudies-literature | 2019 Mar

REPOSITORIES: biostudies-literature

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HLA class II antibodies induce necrotic cell death in human endothelial cells via a lysosomal membrane permeabilization-mediated pathway.

Aljabri Abid A Vijayan Vijith V Stankov Metodi M Nikolin Christoph C Figueiredo Constanca C Blasczyk Rainer R Becker Jan Ulrich JU Linkermann Andreas A Immenschuh Stephan S

Cell death & disease 20190308 3

Antibody-mediated rejection (AMR) is the major cause of allograft loss after solid organ transplantation. Circulating donor-specific antibodies against human leukocyte antigen (HLA), in particular HLA class II antibodies are critical for the pathogenesis of AMR via interactions with endothelial cells (ECs). To investigate the effects of HLA class II antibody ligation to the graft endothelium, a model of HLA-DR antibody-dependent stimulation was utilized in primary human ECs. Antibody ligation of ...[more]

PMID: 30850581

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Project description:Rationale: The adverse health effects of nano-particulate pollutants have attracted much attention in recent years. Carbon nanomaterials are recognized as risk factors for prolonged inflammatory responses and diffuse alveolar injury. Previous research indicated a central role of alveolar macrophages in the pathogenesis of particle-related lung disease, but the underlying mechanism remains largely unknown. Methods: C57BL/6 mice were intratracheally instilled with carbon black nanoparticles (CBNPs). Cell necrosis and the infiltrated neutrophils in the lungs were detected by flow cytometry. Release of mitochondria was observed with Mito Tracker and mitochondrial DNA (mtDNA) was quantified by qPCR via Taqman probes. TLR9-p38 MAPK signaling pathway was detected by Western blotting. The production of lipid chemoattractant leukotriene B4 (LTB4) in the supernatant and bronchoalveolar lavage fluid (BALF) was quantitated using an enzyme immunoassay (EIA). Results: In the present study, we found that a single instillation of CBNPs induced neutrophil influx in C57BL/6 mice as early as 4 h post-exposure following the rapid appearance of cell damage indicators in BALF at 30 min. Macrophages exposed to CBNPs showed necrotic features and were characterized by lysosome rupture, cathepsin B release, reactive oxygen species generation, and reduced intracellular ATP level. Necrosis was partly inhibited by a specific lysosomal cathepsin B inhibitor CA074 Me. Further analyses suggested that the resulting leakage of mtDNA from the necrotic cells activated neutrophils and triggered severe inflammation in vivo. Pulmonary neutrophilic inflammation induced by mtDNA was reduced in TLR9-/- mice. Additionally, mtDNA induced LTB4 production from macrophages, which may contribute to neutrophil recruitment. Conclusion: We demonstrated here that CBNPs induce acute cell necrosis through lysosomal rupture and that mtDNA released from necrotic cells functions as a key event mediating pulmonary neutrophilic inflammation. This study described a novel aspect of the pathogenesis of particle-induced inflammatory response and provided a possible therapeutic target for the regulation of inflammation.

Dataset Information

HLA class II antibodies induce necrotic cell death in human endothelial cells via a lysosomal membrane permeabilization-mediated pathway.

Publications

HLA class II antibodies induce necrotic cell death in human endothelial cells via a lysosomal membrane permeabilization-mediated pathway.

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