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Long-lived macrophage reprogramming drives spike protein-mediated inflammasome activation in COVID-19.

ABSTRACT: Innate immunity triggers responsible for viral control or hyperinflammation in COVID-19 are largely unknown. Here we show that the SARS-CoV-2 spike protein (S-protein) primes inflammasome formation and release of mature interleukin-1β (IL-1β) in macrophages derived from COVID-19 patients but not in macrophages from healthy SARS-CoV-2 naïve individuals. Furthermore, longitudinal analyses reveal robust S-protein-driven inflammasome activation in macrophages isolated from convalescent COVID-19 patients, which correlates with distinct epigenetic and gene expression signatures suggesting innate immune memory after recovery from COVID-19. Importantly, we show that S-protein-driven IL-1β secretion from patient-derived macrophages requires non-specific monocyte pre-activation in vivo to trigger NLRP3-inflammasome signaling. Our findings reveal that SARS-CoV-2 infection causes profound and long-lived reprogramming of macrophages resulting in augmented immunogenicity of the SARS-CoV-2 S-protein, a major vaccine antigen and potent driver of adaptive and innate immune signaling.

SUBMITTER: Theobald SJ

PROVIDER: S-EPMC8350892 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:RATIONALE:A hallmark of chronic inflammatory disorders is persistence of proinflammatory macrophages in diseased tissues. In atherosclerosis, this is associated with dyslipidemia and oxidative stress, but mechanisms linking these phenomena to macrophage activation remain incompletely understood. OBJECTIVE:To investigate mechanisms linking dyslipidemia, oxidative stress, and macrophage activation through modulation of immunometabolism and to explore therapeutic potential targeting specific metabolic pathways. METHODS AND RESULTS:Using a combination of biochemical, immunologic, and ex vivo cell metabolic studies, we report that CD36 mediates a mitochondrial metabolic switch from oxidative phosphorylation to superoxide production in response to its ligand, oxidized LDL (low-density lipoprotein). Mitochondrial-specific inhibition of superoxide inhibited oxidized LDL-induced NF-?B (nuclear factor-?B) activation and inflammatory cytokine generation. RNA sequencing, flow cytometry, 3H-labeled palmitic acid uptake, lipidomic analysis, confocal and electron microscopy imaging, and functional energetics revealed that oxidized LDL upregulated effectors of long-chain fatty acid uptake and mitochondrial import, while downregulating fatty acid oxidation and inhibiting ATP5A (ATP synthase F1 subunit alpha)-an electron transport chain component. The combined effect is long-chain fatty acid accumulation, alteration of mitochondrial structure and function, repurposing of the electron transport chain to superoxide production, and NF-?B activation. Apoe null mice challenged with high-fat diet showed similar metabolic changes in circulating Ly6C+ monocytes and peritoneal macrophages, along with increased CD36 expression. Moreover, mitochondrial reactive oxygen species were positively correlated with CD36 expression in aortic lesional macrophages. CONCLUSIONS:These findings reveal that oxidized LDL/CD36 signaling in macrophages links dysregulated fatty acid metabolism to oxidative stress from the mitochondria, which drives chronic inflammation. Thus, targeting to CD36 and its downstream effectors may serve as potential new strategies against chronic inflammatory diseases such as atherosclerosis.

Project description:Chronic endotheliitis and various cardiovascular co-morbidities are more likely to develop in patients who are recovering from a post-acute SARS-CoV-2 infection. Despite a growing body of clinical data suggesting that the endothelium could be the cause of both cardiac injury and the multi-organ damage found in COVID-19 patients, there is no clear link between endothelial (EC) dysfunction and increased cardiac risk during long COVID. Here, we studied long COVID-19-associated endotheliitis and its implications on cardiac dysfunction. Thrombotic vascular tissues from long COVID patients were harvested and profiled to identify the different mechanisms of viral-induced EC pathogenesis. Human induced pluripotent stem cell (iPSC)–derived ECs were leveraged to model endotheliitis in-a-dish after exposure to SARS-CoV-2, which showed similar EC dysfunction and upregulation of specific cytokines such as CCL2 and IL6, as seen in the primary ECs of long COVID patients. 3D fabricated cardiac organoids generated from iPSC-ECs and iPSC-derived cardiomyocytes (iPSC-CMs) were utilized to understand the pathological influence of endotheliitis on cardiac dysfunction. Notably, cardiac dysfunction was observed only in cardiac organoids that were fabricated with both iPSC-CMs and iPSC-ECs after exposure to SARS-CoV-2. Simultaneous profiling of chromatin accessibility and gene expression dynamics via integration of ATAC-seq and RNA-seq at a single cell resolution revealed CCL2 as the prime cytokine responsible for the non-endothelial “phenotype switching” and the impending cardiac dysfunction in cardiac organoids. This was further validated by high-throughput proteomics that showed CCL2 to be released only by cardiac organoids that were fabricated with iPSC-CMs and iPSC-ECs after SARS-CoV-2 infection. Lastly, disease modeling of the cardiac organoids as well as exposure of human ACE2 transgenic mice to SARS-CoV-2 spike proteins uncovered a putative mechanism for the cardiac dysfunction involving posttranslational modification of cardiac proteins driven by oxidative stress and inflammation. These results suggest that EC-released cytokines can contribute to the pathogenesis of long COVID-associated cardiac dysfunction, and thus a thorough clinical profiling of vascular health could help identify early signs of heart disease in COVID-19 patients.

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Long-lived macrophage reprogramming drives spike protein-mediated inflammasome activation in COVID-19.

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