Your browser doesn't support javascript.
Show: 20 | 50 | 100
Results 1 - 6 de 6
Aging Cell ; 21(6): e13646, 2022 Jun.
Article in English | MEDLINE | ID: covidwho-1883166


Older age and underlying conditions such as diabetes/obesity or immunosuppression are leading host risk factors for developing severe complications from COVID-19 infection. The pathogenesis of COVID-19-related cytokine storm, tissue damage, and fibrosis may be interconnected with fundamental aging processes, including dysregulated immune responses and cellular senescence. Here, we examined effects of key cytokines linked to cellular senescence on expression of SARS-CoV-2 viral entry receptors. We found exposure of human umbilical vein endothelial cells (HUVECs) to the inflammatory cytokines, TNF-α + IFN-γ or a cocktail of TNF-α + IFN-γ + IL-6, increased expression of ACE2/DPP4, accentuated the pro-inflammatory senescence-associated secretory phenotype (SASP), and decreased cellular proliferative capacity, consistent with progression towards a cellular senescence-like state. IL-6 by itself failed to induce substantial effects on viral entry receptors or SASP-related genes, while synergy between TNF-α and IFN-γ initiated a positive feedback loop via hyper-activation of the JAK/STAT1 pathway, causing SASP amplification. Breaking the interactive loop between senescence and cytokine secretion with JAK inhibitor ruxolitinib or antiviral drug remdesivir prevented hyper-inflammation, normalized SARS-CoV-2 entry receptor expression, and restored HUVECs proliferative capacity. This loop appears to underlie cytokine-mediated viral entry receptor activation and links with senescence and hyper-inflammation.

COVID-19 , Interferon-gamma , SARS-CoV-2 , Tumor Necrosis Factor-alpha , COVID-19/drug therapy , COVID-19/virology , Cytokines/immunology , Drug Synergism , Human Umbilical Vein Endothelial Cells/metabolism , Humans , Inflammation/drug therapy , Inflammation/virology , Interferon-gamma/pharmacology , Interleukin-6/metabolism , Receptors, Virus/metabolism , SARS-CoV-2/drug effects , SARS-CoV-2/metabolism , STAT1 Transcription Factor/biosynthesis , STAT1 Transcription Factor/immunology , Tumor Necrosis Factor-alpha/pharmacology
Eur J Immunol ; 52(1): 138-148, 2022 01.
Article in English | MEDLINE | ID: covidwho-1479399


The interferon pathway, a key antiviral defense mechanism, is being considered as a therapeutic target in COVID-19. Both, substitution of interferon and JAK/STAT inhibition to limit cytokine storms have been proposed. However, little is known about possible abnormalities in STAT signaling in immune cells during SARS-CoV-2 infection. We investigated downstream targets of interferon signaling, including STAT1, STAT2, pSTAT1 and 2, and IRF1, 7 and 9 by flow cytometry in 30 patients with COVID-19, 17 with mild, and 13 with severe infection. We report upregulation of STAT1 and IRF9 in mild and severe COVID-19 cases, which correlated with the IFN-signature assessed by Siglec-1 (CD169) expression on peripheral monocytes. Interestingly, Siglec-1 and STAT1 in CD14+ monocytes and plasmablasts showed lower expression among severe cases compared to mild cases. Contrary to the baseline STAT1 expression, the phosphorylation of STAT1 was enhanced in severe COVID-19 cases, indicating a dysbalanced JAK/STAT signaling that fails to induce transcription of interferon stimulated response elements (ISRE). This abnormality persisted after IFN-α and IFN-γ stimulation of PBMCs from patients with severe COVID-19. Data suggest impaired STAT1 transcriptional upregulation among severely infected patients may represent a potential predictive biomarker and would allow stratification of patients for certain interferon-pathway targeted treatments.

COVID-19/immunology , Monocytes/immunology , SARS-CoV-2/immunology , STAT1 Transcription Factor/immunology , Signal Transduction/immunology , Up-Regulation/immunology , Adult , Aged , Female , Humans , Interferon Regulatory Factors/immunology , Male , Middle Aged , Patient Acuity , Phosphorylation/immunology
Signal Transduct Target Ther ; 5(1): 221, 2020 10 06.
Article in English | MEDLINE | ID: covidwho-1387195
J Infect Dis ; 222(5): 734-745, 2020 08 04.
Article in English | MEDLINE | ID: covidwho-711823


Clinical manifestations of coronavirus disease 2019 (COVID-19) vary from asymptomatic virus shedding, nonspecific pharyngitis, to pneumonia with silent hypoxia and respiratory failure. Dendritic cells and macrophages are sentinel cells for innate and adaptive immunity that affect the pathogenesis of severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS). The interplay between SARS-CoV-2 and these cell types remains unknown. We investigated infection and host responses of monocyte-derived dendritic cells (moDCs) and macrophages (MDMs) infected by SARS-CoV-2. MoDCs and MDMs were permissive to SARS-CoV-2 infection and protein expression but did not support productive virus replication. Importantly, SARS-CoV-2 launched an attenuated interferon response in both cell types and triggered significant proinflammatory cytokine/chemokine expression in MDMs but not moDCs. Investigations suggested that this attenuated immune response to SARS-CoV-2 in moDCs was associated with viral antagonism of STAT1 phosphorylation. These findings may explain the mild and insidious course of COVID-19 until late deterioration.

Betacoronavirus/physiology , Coronavirus Infections/immunology , Dendritic Cells/immunology , Interferons/immunology , Monocytes/immunology , Pneumonia, Viral/immunology , STAT1 Transcription Factor/antagonists & inhibitors , Adaptive Immunity , Animals , Betacoronavirus/immunology , Betacoronavirus/isolation & purification , Betacoronavirus/metabolism , COVID-19 , Chemokines/metabolism , Chlorocebus aethiops , Coronavirus Infections/metabolism , Coronavirus Infections/virology , Cytokines/metabolism , Dendritic Cells/metabolism , Dendritic Cells/virology , Humans , Macrophages/immunology , Macrophages/virology , Monocytes/virology , Pandemics , Phosphorylation , Pneumonia, Viral/metabolism , Pneumonia, Viral/virology , SARS-CoV-2 , STAT1 Transcription Factor/immunology , STAT1 Transcription Factor/metabolism , Vero Cells , Virus Replication/physiology , Virus Shedding