Project description:Severe acute respiratory syndrome-associated coronavirus (SARS-CoV) infection causes an immune-mediated disease. We have recently shown that SARS-CoV-induced epithelial Calu-3 cytokines could exacerbate and dampen host inflammatory and T cell responses, respectively, through modulating the functions of macrophages and dendritic cells, thereby suggesting that not only are lung epithelial cells the primary cells of SARS-CoV infection, but they also involve in initiating and orchestrating the host innate and adaptive immunity. Comprehensive evaluation of the complex epithelial signaling to SARS-CoV is, thus, crucial for paving the way to better understand SARS pathogenesis and develop the innovative therapeutics against SARS. Here, based on the microarray-based functional genomics, we reported that 2B4 cells, a clonal derivative of Calu-3 cells, elicited a temporal and spatial activation of nuclear factor (NF)kappaB, activator protein (AP)-1 (ATF2/c-Jun), and interferon regulatory factor (IRF)-3/-7 at 12-, 24-, and 48-hrs post infection (p.i.), respectively, resulting in the activation of many antiviral genes, including interferon (IFN)-Î², -Î»s, SARS-related inflammatory mediators, and various IFN-stimulated genes (ISGs). While elevated responses of IFN-Î² and IFN-Î»s were not detected until 48-hrs p.i., as a consequence of a delayed IRF-3/-7 activation, we showed, for the first time, that both types of IFNs exerted previously under-described non-redundant, complementary, and/or synergistic effects on the epithelial defense against SARS-CoV. Collectively, our results highlight the molecular mechanisms of the sequential activation of virus- and IFN-dependent signaling of lung epithelial cells against SARS-CoV and identify novel cellular targets for future studies, aiming at advancing strategies against SARS. DNA microarrays were performed in the Molecular Genomics (MG) Core Facilities at UTMB. The detailed information about the procedures of microarray analysis has been posted on the MG Core Facilities website (genomics@scms.utmb.edu). To characterize the dynamic, spatial, and temporal changes of the gene expression induced by SARS-CoV, confluent 2B4 cells grown in T-75 flasks were infected with SARS-CoV (MOI=0.1) or remained uninfected (as control) for 12, 24, and 48hrs. Because 2B4 cells were also permissive to the productive infection of Dhori virus (DHOV), a member of the Orthomyxoviridae family within the Thogotovirus genus, resulting in robust responses of IFNs and other pro-inflammatory mediators, we also established parallel cultures of DHOV-infected 2B4 cells (MOI=0.1) for the comparative analysis of global gene expression elicited by SARS-CoV- versus DHOV-infected 2B4 cells. To meet the minimal number required for application of statistical algorithms, we performed the study in triplicate at each time point for mock-, SARS-CoV-, and DHOV-infected cultures, yielding a total of 27 arrays. Briefly, supernatants were harvested from differentially treated cultures at 12-, 24-, and 48-hrs p.i. for subsequent analyses of viral yields and cytokine profiling, whereas the cells were subjected to total RNA extraction by using an RNAqueous-4PCR kit and following the protocol recommended by the manufacturer (Ambion, Austin, TX). Purified RNA samples were sent to our core facility for conversion to cDNA, biotin-labeled, and hybridized to 27 Affymetrix Human Genome U133 Plus 2.0 âGene Chipsâ each of which contained 54,675 probe set identifiers representing more than ~47,400 transcripts that identify ~38,500 well-characterized genes, and various internal controls (Affymetrix, Santa Clara, CA). Mock-infected cells were compared to cells infected with SARS-CoV or DHOV at each time point.

Project description:Objectives: Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) causes the worldwide COVID-19 pandemic. While SARS-CoV-2 can infect people of all ages and both sexes, senior populations are at greatest risk of severe disease and worse outcomes, and sexual dimorphism has been reported in COVID-19. COVID-19 causes damage to multiple organ systems, including the brain. Neurological symptoms are widely observed in patients with Covid-19, with many survivors suffering from persistent neurological impairment, potentially accelerating Alzheimer’s disease (AD). This study aims to investigate the mechanisms underlying the impact of age, and sex on neuroinflammation due to SARS-CoV-2 infection using mouse models. Methods: Wild-type C57BL/6 mice were subjected to intranasal inoculation of SARS-CoV-2 lineage B.1.351, followed by daily body weight monitoring. At 7 dpi, viral burden and inflammatory cytokine/chemokine responses in the lung and brain were determined by quantitative RT-PCR, followed by immunohistochemical and transcriptomic analyses. Results: Older age, male sex, showed increased lung viral loads and severity of SARS-CoV-2 infection in mice. No viral RNA was detected in the brains of infected mice; however, IL-6 and CCL2 mRNA increased significantly, particularly in brains of old and APOE4 mice. Unbiased brain RNA-seq/transcriptomic analysis showed that SARS-CoV-2 infection caused significant changes in gene expression profiles, and pathway analysis identified innate immunity and defense response to virus and other organisms as the major molecular networks affected in the brain by SARS-CoV-2 infection. Conclusions: Our findings demonstrate that age, and sex, modify the progression and outcome of SARS-CoV-2 infection. SARS-CoV-2 infection triggers neuroinflammatory responses despite the lack of detectable virus in the brain. Changes in molecular networks of innate immunity and defense response to microorganisms underlie the impact of SARS-CoV-2 infection in the brain. These findings in mice mimic epidemiological and clinical observations in humans with Covid-19.

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