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Int Immunol ; 33(10): 541-545, 2021 09 25.
Article in English | MEDLINE | ID: covidwho-1575598


The spatial organization of chromatin is known to be highly dynamic in response to environmental stress. However, it remains unknown how chromatin dynamics contributes to or modulates the pathogenesis of immune and infectious diseases. Influenza virus is a single-stranded RNA virus, and transcription and replication of the virus genome occur in the nucleus. Since viral infection is generally associated with virus-driven hijack of the host cellular machineries, influenza virus may utilize and/or affect the nuclear system. In this review article, we focus on recent studies showing that the three-dimensional structure of chromatin changes with influenza virus infection, which affects the pathology of infection. Also, we discuss studies showing the roles of epigenetics in influenza virus infection. Understanding how this affects immune responses may lead to novel strategies to combat immune and infectious diseases.

Chromatin/metabolism , Histone-Lysine N-Methyltransferase/metabolism , Homeodomain Proteins/metabolism , Influenza A virus/immunology , Influenza, Human/pathology , Cell Cycle Proteins/metabolism , Chromosomal Proteins, Non-Histone/metabolism , Histone Code/physiology , Histone-Lysine N-Methyltransferase/genetics , Host-Pathogen Interactions/immunology , Humans , Neoplasms/pathology , Protein Structure, Tertiary , Severity of Illness Index , Virus Replication/physiology
Proc Natl Acad Sci U S A ; 118(38)2021 09 21.
Article in English | MEDLINE | ID: covidwho-1392993


COVID-19 induces a robust, extended inflammatory "cytokine storm" that contributes to an increased morbidity and mortality, particularly in patients with type 2 diabetes (T2D). Macrophages are a key innate immune cell population responsible for the cytokine storm that has been shown, in T2D, to promote excess inflammation in response to infection. Using peripheral monocytes and sera from human patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and a murine hepatitis coronavirus (MHV-A59) (an established murine model of SARS), we identified that coronavirus induces an increased Mφ-mediated inflammatory response due to a coronavirus-induced decrease in the histone methyltransferase, SETDB2. This decrease in SETDB2 upon coronavirus infection results in a decrease of the repressive trimethylation of histone 3 lysine 9 (H3K9me3) at NFkB binding sites on inflammatory gene promoters, effectively increasing inflammation. Mφs isolated from mice with a myeloid-specific deletion of SETDB2 displayed increased pathologic inflammation following coronavirus infection. Further, IFNß directly regulates SETDB2 in Mφs via JaK1/STAT3 signaling, as blockade of this pathway altered SETDB2 and the inflammatory response to coronavirus infection. Importantly, we also found that loss of SETDB2 mediates an increased inflammatory response in diabetic Mϕs in response to coronavirus infection. Treatment of coronavirus-infected diabetic Mφs with IFNß reversed the inflammatory cytokine production via up-regulation of SETDB2/H3K9me3 on inflammatory gene promoters. Together, these results describe a potential mechanism for the increased Mφ-mediated cytokine storm in patients with T2D in response to COVID-19 and suggest that therapeutic targeting of the IFNß/SETDB2 axis in T2D patients may decrease pathologic inflammation associated with COVID-19.

Coronavirus/metabolism , Diabetes Mellitus, Type 2/metabolism , Histone-Lysine N-Methyltransferase/metabolism , Inflammation Mediators/metabolism , Inflammation/virology , Macrophages/metabolism , Animals , COVID-19/immunology , Coronavirus Infections/genetics , Coronavirus Infections/immunology , Cytokine Release Syndrome , Cytokines/metabolism , Diabetes Mellitus, Type 2/genetics , Female , Histone-Lysine N-Methyltransferase/genetics , Humans , Inflammation/metabolism , Inflammation/physiopathology , Male , Mice , Mice, Inbred C57BL , NF-kappa B/metabolism , SARS-CoV-2/metabolism , Signal Transduction
Int J Mol Sci ; 22(14)2021 Jul 13.
Article in English | MEDLINE | ID: covidwho-1308364


Children with the new coronavirus disease 2019 (COVID-19) have milder symptoms and a better prognosis than adult patients. Several investigations assessed type I, II, and III interferon (IFN) signatures in SARS-CoV-2 infected adults, however no data are available for pediatric patients. TRIM28 and SETDB1 regulate the transcription of multiple genes involved in the immune response as well as of human endogenous retroviruses (HERVs). Exogenous viral infections can trigger the activation of HERVs, which in turn can induce inflammatory and immune reactions. Despite the potential cross-talks between SARS-CoV-2 infection and TRIM28, SETDB1, and HERVs, information on their expressions in COVID-19 patients is lacking. We assessed, through a PCR real time Taqman amplification assay, the transcription levels of six IFN-I stimulated genes, IFN-II and three of its sensitive genes, three IFN-lIIs, as well as of TRIM28, SETDB1, pol genes of HERV-H, -K, and -W families, and of env genes of Syncytin (SYN)1, SYN2, and multiple sclerosis-associated retrovirus (MRSV) in peripheral blood from COVID-19 children and in control uninfected subjects. Higher expression levels of IFN-I and IFN-II inducible genes were observed in 36 COVID-19 children with mild or moderate disease as compared to uninfected controls, whereas their concentrations decreased in 17 children with severe disease and in 11 with multisystem inflammatory syndrome (MIS-C). Similar findings were found for the expression of TRIM-28, SETDB1, and every HERV gene. Positive correlations emerged between the transcriptional levels of type I and II IFNs, TRIM28, SETDB1, and HERVs in COVID-19 patients. IFN-III expressions were comparable in each group of subjects. This preserved induction of IFN-λs could contribute to the better control of the infection in children as compared to adults, in whom IFN-III deficiency has been reported. The upregulation of IFN-I, IFN-II, TRIM28, SETDB1, and HERVs in children with mild symptoms, their declines in severe cases or with MIS-C, and the positive correlations of their transcription in SARS-CoV-2-infected children suggest that they may play important roles in conditioning the evolution of the infection.

COVID-19/epidemiology , COVID-19/metabolism , Endogenous Retroviruses/metabolism , SARS-CoV-2/isolation & purification , Severity of Illness Index , COVID-19/pathology , COVID-19/virology , Case-Control Studies , Child , Endogenous Retroviruses/genetics , Female , Histone-Lysine N-Methyltransferase/genetics , Histone-Lysine N-Methyltransferase/metabolism , Humans , Interferon Type I/genetics , Interferon Type I/metabolism , Interferon-gamma/genetics , Interferon-gamma/metabolism , Interferons/genetics , Interferons/metabolism , Italy/epidemiology , Male , Tripartite Motif-Containing Protein 28/genetics , Tripartite Motif-Containing Protein 28/metabolism