Inflammasome signaling proteins as biomarkers of COVID-19.

Introduction: One of the main characteristics of COVID-19 is an exacerbated inflammatory response that results in cardiometabolic complications and dysfunction in the nervous system. Moreover, these complications may extend beyond the period of active SARS-CoV2 infection and even extend over a year. Thus, it is important to better understand the contribution of the inflammatory responses in COVID-19 patients, not just in the acute phase but also after the infection has subsided. Methods: We measured the protein levels of inflammasome signaling proteins using Simple Plex microfluidics technology in patients with an active SARS-CoV2 infection and in recovered patients to determine their potential use as biomarkers of COVID-19. We carried out statistical analyses to identify which proteins were increased in COVID-19 patients with active infection and in recovered patients. The receiver operating characteristics (ROC) were calculated for each analyte to determine their potential fit as biomarkers. Results: The inflammasome proteins caspase-1, apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC), interleukin (IL)-1ß and IL-18 were elevated in the plasma of patients with active infection and remained elevated after the infection was resolved for approximately 2 months after. Levels of caspase-1 and ASC continued to increase long after patients had recovered from the infection. Furthermore, when measuring biomarkers of inflammation during active infection, analyses with area under the curve (AUC) values above 0.75 indicated that caspase-1, ASC, IL-1ß and IL-18 are reliable biomarkers of the inflammatory response during active COVID-19 infection. Moreover, when measuring biomarkers of inflammation after recovery from active infection, caspase-1 and ASC presented AUC values above 0.9. Discussion: These findings indicate that inflammasome signaling proteins can be used to reliably monitor the inflammatory innate immune response in COVID-19 patients.

Cytokine Profiling in Different SARS-CoV-2 Genetic Variants.

This study is a successor of our previous work concerning changes in the chemokine profile in infection that are associated with different SARS-CoV-2 genetic variants. The goal of our study was to take into account both the virus and the host immune system by assessing concentrations of cytokines in patients infected with different SARS-CoV-2 variants (ancestral Wuhan strain, Alpha, Delta and Omicron). Our study was performed on 340 biological samples taken from COVID-19 patients and healthy donors in the timespan between May 2020 and April 2022. We performed genotyping of the virus in nasopharyngeal swabs, which was followed by assessment of cytokines' concentration in blood plasma. We noted that out of nearly 30 cytokines, only four showed stable elevation independently of the variant (IL-6, IL-10, IL-18 and IL-27), and we believe them to be 'constant' markers for COVID-19 infection. Cytokines that were studied as potential biomarkers lose their diagnostic value as the virus evolves, and the specter of potential targets for predictive models is narrowing. So far, only four cytokines (IL-6, IL-10, IL-18, and IL-27) showed a consistent rise in concentrations independently of the genetic variant of the virus. Although we believe our findings to be of scientific interest, we still consider them inconclusive; further investigation and comparison of immune responses to different variants of SARS-CoV-2 is required.

Interleukin-18-primed human umbilical cord-mesenchymal stem cells achieve superior therapeutic efficacy for severe viral pneumonia via enhancing T-cell immunosuppression.

Coronavirus disease 2019 (COVID-19) treatments are still urgently needed for critically and severely ill patients. Human umbilical cord-mesenchymal stem cells (hUC-MSCs) infusion has therapeutic benefits in COVID-19 patients; however, uncertain therapeutic efficacy has been reported in severe patients. In this study, we selected an appropriate cytokine, IL-18, based on the special cytokine expression profile in severe pneumonia of mice induced by H1N1virus to prime hUC-MSCs in vitro and improve the therapeutic effect of hUC-MSCs in vivo. In vitro, we demonstrated that IL-18-primed hUC-MSCs (IL18-hUCMSC) have higher proliferative ability than non-primed hUC-MSCs (hUCMSCcon). In addition, VCAM-1, MMP-1, TGF-ß1, and some chemokines (CCL2 and CXCL12 cytokines) are more highly expressed in IL18-hUCMSCs. We found that IL18-hUCMSC significantly enhanced the immunosuppressive effect on CD3+ T-cells. In vivo, we demonstrated that IL18-hUCMSC infusion could reduce the body weight loss caused by a viral infection and significantly improve the survival rate. Of note, IL18-hUCMSC can also significantly attenuate certain clinical symptoms, including reduced activity, ruffled fur, hunched backs, and lung injuries. Pathologically, IL18-hUCMSC transplantation significantly enhanced the inhibition of inflammation, viral load, fibrosis, and cell apoptosis in acute lung injuries. Notably, IL18-hUCMSC treatment has a superior inhibitory effect on T-cell exudation and proinflammatory cytokine secretion in bronchoalveolar lavage fluid (BALF). Altogether, IL-18 is a promising cytokine that can prime hUC-MSCs to improve the efficacy of precision therapy against viral-induced pneumonia, such as COVID-19.

Severe COVID-19 patients display hyper-activated NK cells and NK cell-platelet aggregates.

COVID-19 is characterised by a broad spectrum of clinical and pathological features. Natural killer (NK) cells play an important role in innate immune responses to viral infections. Here, we analysed the phenotype and activity of NK cells in the blood of COVID-19 patients using flow cytometry, single-cell RNA-sequencing (scRNA-seq), and a cytotoxic killing assay. In the plasma of patients, we quantified the main cytokines and chemokines. Our cohort comprises COVID-19 patients hospitalised in a low-care ward unit (WARD), patients with severe COVID-19 disease symptoms hospitalised in intensive care units (ICU), and post-COVID-19 patients, who were discharged from hospital six weeks earlier. NK cells from hospitalised COVID-19 patients displayed an activated phenotype with substantial differences between WARD and ICU patients and the timing when samples were taken post-onset of symptoms. While NK cells from COVID-19 patients at an early stage of infection showed increased expression of the cytotoxic molecules perforin and granzyme A and B, NK cells from patients at later stages of COVID-19 presented enhanced levels of IFN-γ and TNF-α which were measured ex vivo in the absence of usual in vitro stimulation. These activated NK cells were phenotyped as CD49a+CD69a+CD107a+ cells, and their emergence in patients correlated to the number of neutrophils, and plasma IL-15, a key cytokine in NK cell activation. Despite lower amounts of cytotoxic molecules in NK cells of patients with severe symptoms, majority of COVID-19 patients displayed a normal cytotoxic killing of Raji tumour target cells. In vitro stimulation of patients blood cells by IL-12+IL-18 revealed a defective IFN-γ production in NK cells of ICU patients only, indicative of an exhausted phenotype. ScRNA-seq revealed, predominantly in patients with severe COVID-19 disease symptoms, the emergence of an NK cell subset with a platelet gene signature that we identified by flow and imaging cytometry as aggregates of NK cells with CD42a+CD62P+ activated platelets. Post-COVID-19 patients show slow recovery of NK cell frequencies and phenotype. Our study points to substantial changes in NK cell phenotype during COVID-19 disease and forms a basis to explore the contribution of platelet-NK cell aggregates to antiviral immunity against SARS-CoV-2 and disease pathology.

Activation mechanisms of monocytes/macrophages in adult-onset Still disease.

Adult onset Still disease (AOSD) is a systemic inflammatory disorder characterized by skin rash, spiking fever, arthritis, sore throat, lymphadenopathy, and hepatosplenomegaly. Although the etiology of this disease has not been fully clarified, both innate and acquired immune responses could contribute to its pathogenesis. Hyperactivation of macrophages and neutrophils along with low activation of natural killer (NK) cells in innate immunity, as well as hyperactivation of Th1 and Th17 cells, whereas low activation of regulatory T cells (Tregs) in acquired immunity are involved in the pathogenic process of AOSD. In innate immunity, activation of monocytes/macrophages might play central roles in the development of AOSD and macrophage activation syndrome (MAS), a severe life-threating complication of AOSD. Regarding the activation mechanisms of monocytes/macrophages in AOSD, in addition to type II interferon (IFN) stimulation, several pathways have recently been identified, such as the pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs)-pattern recognition receptors (PRRs) axis, and neutrophil extracellular traps (NETs)-DNA. These stimulations on monocytes/macrophages cause activation of the nucleotide-binding oligomerization domain, leucine-rich repeat, and pyrin domain (NLRP) 3 inflammasomes, which trigger capase-1 activation, resulting in conversion of pro-IL-1ß and pro-IL-18 into mature forms. Thereafter, IL-1ß and IL-18 produced by activated monocytes/macrophages contribute to various clinical features in AOSD. We identified placenta-specific 8 (PLAC8) as a specifically increased molecule in monocytes of active AOSD, which correlated with serum levels of CRP, ferritin, IL-1ß, and IL-18. Interestingly, PLAC8 could suppress the synthesis of pro-IL-1ß and pro-IL-18 via enhanced autophagy; thus, PLAC8 seems to be a regulatory molecule in AOSD. These findings for the activation mechanisms of monocytes/macrophages could shed light on the pathogenesis and development of a novel therapeutic strategy for AOSD.

The multifaceted roles of NLRP3-modulating proteins in virus infection.

The innate immune response to viruses is critical for the correct establishment of protective adaptive immunity. Amongst the many pathways involved, the NLRP3 [nucleotide-binding oligomerisation domain (NOD)-like receptor protein 3 (NLRP3)] inflammasome has received considerable attention, particularly in the context of immunity and pathogenesis during infection with influenza A (IAV) and SARS-CoV-2, the causative agent of COVID-19. Activation of the NLRP3 inflammasome results in the secretion of the proinflammatory cytokines IL-1ß and IL-18, commonly coupled with pyroptotic cell death. While this mechanism is protective and key to host defense, aberrant NLRP3 inflammasome activation causes a hyperinflammatory response and excessive release of cytokines, both locally and systemically. Here, we discuss key molecules in the NLRP3 pathway that have also been shown to have significant roles in innate and adaptive immunity to viruses, including DEAD box helicase X-linked (DDX3X), vimentin and macrophage migration inhibitory factor (MIF). We also discuss the clinical opportunities to suppress NLRP3-mediated inflammation and reduce disease severity.

Soluble P2X7 Receptor Is Elevated in the Plasma of COVID-19 Patients and Correlates With Disease Severity.

Inflammation is a tightly coordinated response against bacterial and viral infections, triggered by the production of pro-inflammatory cytokines. SARS-CoV-2 infection induces COVID-19 disease, characterized by an inflammatory response mediated through the activation of the NLRP3 inflammasome, which results in the production of IL-1ß and IL-18 along with pyroptotic cell death. The NLRP3 inflammasome could be also activated by sterile danger signals such as extracellular ATP triggering the purinergic P2X7 receptor. Severe inflammation in the lungs of SARS-CoV-2-infected individuals is associated with pneumonia, hypoxia and acute respiratory distress syndrome, these being the causes of death associated with COVID-19. Both the P2X7 receptor and NLRP3 have been considered as potential pharmacological targets for treating inflammation in COVID-19. However, there is no experimental evidence of the involvement of the P2X7 receptor during COVID-19 disease. In the present study, we determined the concentration of different cytokines and the P2X7 receptor in the plasma of COVID-19 patients and found that along with the increase in IL-6, IL-18 and the IL-1 receptor antagonist in the plasma of COVID-19 patients, there was also an increase in the purinergic P2X7 receptor. The increase in COVID-19 severity and C-reactive protein concentration positively correlated with increased concentration of the P2X7 receptor in the plasma, but not with the IL-18 cytokine. The P2X7 receptor was found in the supernatant of human peripheral blood mononuclear cells after inflammasome activation. Therefore, our data suggest that determining the levels of the P2X7 receptor in the plasma could be a novel biomarker of COVID-19 severity.

Structural basis of human IL-18 sequestration by the decoy receptor IL-18 binding protein in inflammation and tumor immunity.

Human Interleukin-18 (IL-18) is an omnipresent proinflammatory cytokine of the IL-1 family with central roles in autoimmune and inflammatory diseases and serves as a staple biomarker in the evaluation of inflammation in physiology and disease, including the inflammatory phase of COVID-19. The sequestration of IL-18 by its soluble decoy receptor IL-18-Binding Protein (IL-18BP) is critical to the regulation of IL-18 activity. Since an imbalance in expression and circulating levels of IL-18 is associated with disease, structural insights into how IL-18BP outcompetes binding of IL-18 by its cognate cell-surface receptors are highly desirable; however, the structure of human IL-18BP in complex with IL-18 has been elusive. Here, we elucidate the sequestration mechanism of human IL-18 mediated by IL-18BP based on the crystal structure of the IL-18:IL-18BP complex. These detailed structural snapshots reveal the interaction landscape leading to the ultra-high affinity of IL-18BP toward IL-18 and identify substantial differences with respect to previously characterized complexes of IL-18 with IL-18BP of viral origin. Furthermore, our structure captured a fortuitous higher-order assembly between IL-18 and IL-18BP coordinated by a disulfide-bond distal to the binding surface connecting IL-18 and IL-18BP molecules from different complexes, resulting in a novel tetramer with 2:2 stoichiometry. This tetrapartite assembly was found to restrain IL-18 activity more effectively than the canonical 1:1 complex. Collectively, our findings provide a framework for innovative, structure-driven therapeutic strategies and further functional interrogation of IL-18 in physiology and disease.

Listeria toxin promotes phosphorylation of the inflammasome adaptor ASC through Lyn and Syk to exacerbate pathogen expansion.

Inflammasome activation exacerbates infectious disease caused by pathogens such as Listeria monocytogenes, Staphylococcus aureus, and severe acute respiratory syndrome coronavirus 2. Although these pathogens activate host inflammasomes to regulate pathogen expansion, the mechanisms by which pathogen toxins contribute to inflammasome activation remain poorly understood. Here we show that activation of inflammasomes by Listeria infection is promoted by amino acid residue T223 of listeriolysin O (LLO) independently of its pore-forming activity. LLO T223 is critical for phosphorylation of the inflammasome adaptor ASC at amino acid residue Y144 through Lyn-Syk signaling, which is essential for ASC oligomerization. Notably, a Listeria mutant expressing LLO T223A is impaired in inducing ASC phosphorylation and inflammasome activation. Furthermore, the virulence of LLO T223A mutant is markedly attenuated in vivo due to impaired ability to activate the inflammasome. Our results reveal a function of a pathogen toxin that exacerbates infection by promoting phosphorylation of ASC.

Cardiovascular Risk After SARS-CoV-2 Infection Is Mediated by IL18/IL18R1/HIF-1 Signaling Pathway Axis.

Objectives: Currently, cardiovascular risk associated with COVID-19 has been brought to people's attention, but the mechanism is not clear. The aim of this study is to elucidate the mechanisms based on multiple omics data. Methodology: Weighted gene co-expression network analysis (WGCNA) was used to identify key pathways. Combination analysis with aneurysm and atherosclerosis related pathways, hypoxia induced factor-1 (HIF-1) signaling were identified as key pathways of the increased cardiovascular risk associated with COVID-19. ScMLnet algorithm based on scRNA-seq was used to explore the regulation of HIF-1 pathway by intercellular communication. Proteomic analysis was used to detect the regulatory mechanisms between IL18 and HIF-1 signaling pathway. Pseudo time locus analysis was used to study the regulation of HIF1 signaling pathway in macrophages and vascular smooth muscle cells (VSMC) phenotypic transformation. The Virtual Inference of protein-activity by Enriched Regulon (VIPER) analysis was used to study the activity of regulatory proteins. Epigenetic analysis based on methylation revealed epigenetic changes in PBMC after SARS-CoV-2 infection. Potential therapeutic compounds were explored by using Cmap algorithm. Results: HIF-1 signaling pathway is a common key pathway for aneurysms, atherosclerosis and SARS-CoV-2 infection. Intercellular communication analysis showed that macrophage-derived interleukin-18 (IL-18) activates the HIF-1 signaling pathway through IL18R1. Proteomic analysis showed that IL18/IL18R1 promote NF-κB entry into the nucleus, and activated the HIF-1 signaling pathway. Macrophage-derived IL18 promoted the M1 polarization of macrophages and the syntactic phenotype transformation of VSMCs. MAP2K1 mediates the functional regulation of HIF-1 signaling pathway in various cell types. Epigenetic changes in PBMC after COVID-19 infection are characterized by activation of the type I interferon pathway. MEK inhibitors are the promising compounds for the treatment of HIF-1 overactivation. Conclusions: The IL18/IL18R1/HIF1A axis is expected to be an therapeutic target for cardiovascular protection after SARS-CoV-2 infection. MEK inhibitors may be an choice for cardiovascular protection after SARS-COV-2 infection.

Profound Treg perturbations correlate with COVID-19 severity.

The hallmark of severe COVID-19 is an uncontrolled inflammatory response, resulting from poorly understood immunological dysfunction. We hypothesized that perturbations in FoxP3+ T regulatory cells (Treg), key enforcers of immune homeostasis, contribute to COVID-19 pathology. Cytometric and transcriptomic profiling revealed a distinct Treg phenotype in severe COVID-19 patients, with an increase in Treg proportions and intracellular levels of the lineage-defining transcription factor FoxP3, correlating with poor outcomes. These Tregs showed a distinct transcriptional signature, with overexpression of several suppressive effectors, but also proinflammatory molecules like interleukin (IL)-32, and a striking similarity to tumor-infiltrating Tregs that suppress antitumor responses. Most marked during acute severe disease, these traits persisted somewhat in convalescent patients. A screen for candidate agents revealed that IL-6 and IL-18 may individually contribute different facets of these COVID-19-linked perturbations. These results suggest that Tregs may play nefarious roles in COVID-19, by suppressing antiviral T cell responses during the severe phase of the disease, and by a direct proinflammatory role.

Management of Acute Lung Injury: Palmitoylethanolamide as a New Approach.

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are common and devastating clinical disorders with high mortality and no specific therapy. Lipopolysaccharide (LPS) is usually used intratracheally to induce ALI in mice. The aim of this study was to examine the effects of an ultramicronized preparation of palmitoylethanolamide (um-PEA) in mice subjected to LPS-induced ALI. Histopathological analysis reveals that um-PEA reduced alteration in lung after LPS intratracheal administration. Besides, um-PEA decreased wet/dry weight ratio and myeloperoxidase, a marker of neutrophils infiltration, macrophages and total immune cells number and mast cells degranulation in lung. Moreover, um-PEA could also decrease cytokines release of interleukin (IL)-6, interleukin (IL)-1ß, tumor necrosis factor (TNF)-α and interleukin (IL)-18. Furthermore, um-PEA significantly inhibited the phosphorylation of nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha (IκBα) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) activation in ALI, and at the same time decreased extracellular signal-regulated kinase 1/2 (ERK1/2), c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (p38/MAPK) expression, that was increased after LPS administration. Our study suggested that um-PEA contrasted LPS-induced ALI, exerting its potential role as an adjuvant anti-inflammatory therapeutic for treating lung injury, maybe also by p38/NF-κB pathway.

MAIT cell activation augments adenovirus vector vaccine immunogenicity.

Mucosal-associated invariant T (MAIT) cells are innate sensors of viruses and can augment early immune responses and contribute to protection. We hypothesized that MAIT cells may have inherent adjuvant activity in vaccine platforms that use replication-incompetent adenovirus vectors. In mice and humans, ChAdOx1 (chimpanzee adenovirus Ox1) immunization robustly activated MAIT cells. Activation required plasmacytoid dendritic cell (pDC)-derived interferon (IFN)-α and monocyte-derived interleukin-18. IFN-α-induced, monocyte-derived tumor necrosis factor was also identified as a key secondary signal. All three cytokines were required in vitro and in vivo. Activation of MAIT cells positively correlated with vaccine-induced T cell responses in human volunteers and MAIT cell-deficient mice displayed impaired CD8+ T cell responses to multiple vaccine-encoded antigens. Thus, MAIT cells contribute to the immunogenicity of adenovirus vectors, with implications for vaccine design.

Integrated immune dynamics define correlates of COVID-19 severity and antibody responses.

SARS-CoV-2 causes a spectrum of COVID-19 disease, the immunological basis of which remains ill defined. We analyzed 85 SARS-CoV-2-infected individuals at acute and/or convalescent time points, up to 102 days after symptom onset, quantifying 184 immunological parameters. Acute COVID-19 presented with high levels of IL-6, IL-18, and IL-10 and broad activation marked by the upregulation of CD38 on innate and adaptive lymphocytes and myeloid cells. Importantly, activated CXCR3+cTFH1 cells in acute COVID-19 significantly correlate with and predict antibody levels and their avidity at convalescence as well as acute neutralization activity. Strikingly, intensive care unit (ICU) patients with severe COVID-19 display higher levels of soluble IL-6, IL-6R, and IL-18, and hyperactivation of innate, adaptive, and myeloid compartments than patients with moderate disease. Our analyses provide a comprehensive map of longitudinal immunological responses in COVID-19 patients and integrate key cellular pathways of complex immune networks underpinning severe COVID-19, providing important insights into potential biomarkers and immunotherapies.

Elevated markers of gut leakage and inflammasome activation in COVID-19 patients with cardiac involvement.

BACKGROUND: A high proportion of COVID-19 patients have cardiac involvement, even those without known cardiac disease. Downregulation of angiotensin converting enzyme 2 (ACE2), a receptor for SARS-CoV-2 and the renin-angiotensin system, as well as inflammatory mechanisms have been suggested to play a role. ACE2 is abundant in the gut and associated with gut microbiota composition. We hypothesized that gut leakage of microbial products, and subsequent inflammasome activation could contribute to cardiac involvement in COVID-19 patients. METHODS: Plasma levels of a gut leakage marker (LPS-binding protein, LBP), a marker of enterocyte damage (intestinal fatty acid binding protein, IFABP), a gut homing marker (CCL25, ligand for chemokine receptor CCR9) and markers of inflammasome activation (IL-1ß, IL-18 and their regulatory proteins) were measured at three time points (day 1, 3-5 and 7-10) in 39 hospitalized COVID-19 patients and related to cardiac involvement. RESULTS: Compared to controls, COVID-19 patients had elevated plasma levels of LBP and CCL25 but not IFABP, suggesting impaired gut barrier function and accentuated gut homing of T cells without excessive enterocyte damage. Levels of LBP were twice as high at baseline in patients with elevated cardiac markers compared with those without and remained elevated during hospitalization. Also, markers of inflammasome activation were moderately elevated in patients with cardiac involvement. LBP was associated with higher NT-pro-BNP levels, whereas IL-18, IL-18BP and IL-1Ra were associated with higher troponin levels. CONCLUSION: Patients with cardiac involvement had elevated markers of gut leakage and inflammasome activation, suggestive of a potential gut-heart axis in COVID-19.

Mapping Systemic Inflammation and Antibody Responses in Multisystem Inflammatory Syndrome in Children (MIS-C).

Initially, children were thought to be spared from disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, a month into the epidemic, a novel multisystem inflammatory syndrome in children (MIS-C) emerged. Herein, we report on the immune profiles of nine MIS-C cases. All MIS-C patients had evidence of prior SARS-CoV-2 exposure, mounting an antibody response with intact neutralization capability. Cytokine profiling identified elevated signatures of inflammation (IL-18 and IL-6), lymphocytic and myeloid chemotaxis and activation (CCL3, CCL4, and CDCP1), and mucosal immune dysregulation (IL-17A, CCL20, and CCL28). Immunophenotyping of peripheral blood revealed reductions of non-classical monocytes, and subsets of NK and T lymphocytes, suggesting extravasation to affected tissues. Finally, profiling the autoantigen reactivity of MIS-C plasma revealed both known disease-associated autoantibodies (anti-La) and novel candidates that recognize endothelial, gastrointestinal, and immune-cell antigens. All patients were treated with anti-IL-6R antibody and/or IVIG, which led to rapid disease resolution.

Association of Cardiac Infection With SARS-CoV-2 in Confirmed COVID-19 Autopsy Cases.

Importance: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can be documented in various tissues, but the frequency of cardiac involvement as well as possible consequences are unknown. Objective: To evaluate the presence of SARS-CoV-2 in the myocardial tissue from autopsy cases and to document a possible cardiac response to that infection. Design, Setting, and Participants: This cohort study used data from consecutive autopsy cases from Germany between April 8 and April 18, 2020. All patients had tested positive for SARS-CoV-2 in pharyngeal swab tests. Exposures: Patients who died of coronavirus disease 2019. Main Outcomes and Measures: Incidence of SARS-CoV-2 positivity in cardiac tissue as well as CD3+, CD45+, and CD68+ cells in the myocardium and gene expression of tumor necrosis growth factor α, interferon γ, chemokine ligand 5, as well as interleukin-6, -8, and -18. Results: Cardiac tissue from 39 consecutive autopsy cases were included. The median (interquartile range) age of patients was 85 (78-89) years, and 23 (59.0%) were women. SARS-CoV-2 could be documented in 24 of 39 patients (61.5%). Viral load above 1000 copies per µg RNA could be documented in 16 of 39 patients (41.0%). A cytokine response panel consisting of 6 proinflammatory genes was increased in those 16 patients compared with 15 patients without any SARS-CoV-2 in the heart. Comparison of 15 patients without cardiac infection with 16 patients with more than 1000 copies revealed no inflammatory cell infiltrates or differences in leukocyte numbers per high power field. Conclusions and Relevance: In this analysis of autopsy cases, viral presence within the myocardium could be documented. While a response to this infection could be reported in cases with higher virus load vs no virus infection, this was not associated with an influx of inflammatory cells. Future investigations should focus on evaluating the long-term consequences of this cardiac involvement.