COVID-19 and influenza infections mediate distinct pulmonary cellular and transcriptomic changes [scRNA-Seq]
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ABSTRACT: SARS-CoV-2 infection can cause persistent respiratory sequelae, as seen in long COVID. However, the underlying mechanisms remain unclear. To investigate pulmonary cellular and transcriptomic changes mediated by SARS-CoV-2 and influenza infection, we characterized the SARS-CoV-2-infected K18-hACE2 (K18) mice and compared their lung recovery with a mouse-adapted influenza model and verified the finding in SARS-CoV-2-infected nonhuman primates and in fatal human COVID-19 cases. K18-hACE2 mice infected with a sub-lethal dose of SARS-CoV-2 lost body weight from 1 - 8 days post-infection (DPI), and then gradually returned to baseline weight between 8 -13 DPI. Infected mice showed patchy pneumonia associated with histiocytic inflammation, collagen deposition, and increased pulmonary interferon and inflammatory response signature gene changes at 21 and 45 DPI. Transcriptomic analyses revealed that compared to influenza-infected mice, SARS-CoV-2-infected mice had reduced interferon-gamma/alpha responses at 4 DPI and failed to induce keratin 5 (Krt5) at 6 DPI in lung, a marker of nascent pulmonary progenitor cells. They also showed reduced activation of epithelial-to-mesenchymal transition and apical junction pathways compared to influenza (Flu)-infected mice. Histologically, influenza- but not SARS-CoV-2- infected mice showed extensive Krt5+ “pods” structure co-stained with stem cell markers Trp63/ NGFR proliferated in the pulmonary consolidation area at both 7 and 14 DPI, with regression at 21 DPI. These Krt5+ “pods” and proliferative stem cells were not observed in SARS-CoV-2 infection in the lungs of humans or nonhuman primates. These results suggest that SARS-CoV-2 infection fails to induce nascent Krt5+ cell proliferation in consolidated regions, leading to incomplete repair of the injured lung which may underlie the persistent clinical symptoms of long COVID.
Project description:SARS-CoV-2 infection can cause persistent respiratory sequelae, as seen in long COVID. However, the underlying mechanisms remain unclear. To investigate pulmonary cellular and transcriptomic changes mediated by SARS-CoV-2 and influenza infection, we characterized the SARS-CoV-2-infected K18-hACE2 (K18) mice and compared their lung recovery with a mouse-adapted influenza model and verified the finding in SARS-CoV-2-infected nonhuman primates and in fatal human COVID-19 cases. K18-hACE2 mice infected with a sub-lethal dose of SARS-CoV-2 lost body weight from 1 - 8 days post-infection (DPI), and then gradually returned to baseline weight between 8 -13 DPI. Infected mice showed patchy pneumonia associated with histiocytic inflammation, collagen deposition, and increased pulmonary interferon and inflammatory response signature gene changes at 21 and 45 DPI. Transcriptomic analyses revealed that compared to influenza-infected mice, SARS-CoV-2-infected mice had reduced interferon-gamma/alpha responses at 4 DPI and failed to induce keratin 5 (Krt5) at 6 DPI in lung, a marker of nascent pulmonary progenitor cells. They also showed reduced activation of epithelial-to-mesenchymal transition and apical junction pathways compared to influenza (Flu)-infected mice. Histologically, influenza- but not SARS-CoV-2- infected mice showed extensive Krt5+ “pods” structure co-stained with stem cell markers Trp63/ NGFR proliferated in the pulmonary consolidation area at both 7 and 14 DPI, with regression at 21 DPI. These Krt5+ “pods” and proliferative stem cells were not observed in SARS-CoV-2 infection in the lungs of humans or nonhuman primates. These results suggest that SARS-CoV-2 infection fails to induce nascent Krt5+ cell proliferation in consolidated regions, leading to incomplete repair of the injured lung which may underlie the persistent clinical symptoms of long COVID.
Project description:To further identify and understand the molecular and immunological correlates of pathology for SARS-CoV infection, we infected 129/S6/SvEv or B129 mice with the TOR2 strain of SARS-CoV. SARS-CoV was detected in the lung and nasal turbinates of infected mice peaking at 1 day post infection (DPI) in both tissues before decreasing rapidly to levels below detection at 7 DPI and 3 DPI, respectively. Pulmonary lesions in virus-infected animals included bronchiolar, peribronchiolar, and perivascular foci of mild to moderate subacute inflammation. Chronic inflammation included inflammatory macrophages, lymphocytes, and plasma cells. Neutralizing antibodies appeared on 5 DPI (IgM); converting to IgG on 7 DPI. Despite the prevailing notion that SARS-CoV interferes with the induction of interferon (IFN) signaling, mice infected with SARS-CoV in vivo demonstrated significantly increased expression of innate antiviral interferon (IFN) response genes (IRGs) in the lungs during the first week of acute infection. By the end of the second week of infection, coordinated expression of MHC class I / II and antigen presentation genes occurred in correlation with declining viral titres. Collectively, the mouse data suggests that robust IFN-driven innate immune responses and a critical shift from innate to adaptive immune responses is necessary for clearance and recovery from SARS-CoV infection. Keywords: time course
Project description:The mechanisms by which pulmonary lesions and fibrosis are generated during SARS-CoV infection are not known. Using high-throughput mRNA profiling, we examined the transcriptional response of wild-type (WT), type I interferon receptor knockout (IFNAR1−/−), and STAT1 knockout (STAT1−/−) mice infected with a recombinant mouse-adapted SARS-CoV (rMA15) to better understand the contribution of specific gene expression changes to disease progression. Ten week old 129S6/SvEv wild-type, STAT1−/− (Taconic Farms, Germantown, NY), and IFNAR1−/− mice bred on a 129SvEv background were anesthetized with a ketamine and infected intranasally with either phosphate-buffered saline (PBS) alone (Invitrogen, Carlsbad, CA) or 1 × 10^5 PFU rMA15-PBS. Mice were euthanized and left lungs were harvested from individual mice (a total of 3 infected mice from each strain) at days 2, 5, and 9 postinfection (dpi) for microarray analyses. Lung samples were taken from mock-infected animals from each of the strains at 5 dpi.
Project description:Coronavirus disease 2019 (COVID-19), caused by infection with the enveloped RNA betacoronavirus, SARS-CoV-2, led to a global pandemic involving over 7 million deaths. Macrophage inflammatory responses impact COVID-19 severity; however, it is unclear whether macrophages are infected by SARS-CoV-2. We sought to identify mechanisms regulating macrophage expression of ACE2, the primary receptor for SARS-CoV-2, and to determine if macrophages are susceptible to productive infection. We developed a humanized ACE2 (hACE2) mouse whereby hACE2 cDNA was cloned into the mouse ACE2 locus under control of the native promoter. We validated susceptibility of hACE2 mice to SARS-CoV-2 infection relative to wild-type mice or an established K18-hACE2 model of acute fulminating disease. Intranasal exposure to SARS-CoV-2 led to pulmonary consolidations with cellular infiltrate, edema, and hemorrhage, consistent with pneumonia, yet unlike the K18-hACE2 model, hACE2 mice survived and maintained stable weight. Infected hACE2 mice also exhibited a unique plasma chemokine, cytokine, and growth factor, inflammatory signature relative to K18-hACE2 mice. Infected hACE2 mice demonstrated evidence of viral replication in infiltrating lung macrophages, and infection of macrophages in vitro revealed a transcriptional profile indicative of altered RNA and ribosomal processing machinery as well as activated cellular antiviral defense. Macrophage IL-1β-driven NF-B transcription of ACE2 appeared to be an important mechanism of dynamic ACE2 upregulation, promoting macrophage susceptibility to infection. Experimental models of COVID-19 that make use of native hACE2 expression will allow for mechanistic insight into factors that can either promote host resilience or increase susceptibility to worsening severity of infection.
Project description:hACE2 transgenic mice were infected with the original SARS-CoV-2 strain (B.1) and the Beta (B.1.351) variant. Lung and spleen samples were collected 1 day post infection (DPI), 3 DPI and 5 DPI, and mRNA was sequenced.
Project description:Rapid emergence of antigenic distinct SARS-CoV-2 variants implies a greater risk of reinfection as viruses can escape neutralizing antibodies induced by vaccination or previous viral exposure. Disease severity during COVID-19 depends on many variables such as age-related comorbidities, host immune status and genetic variation. The host immune response during infection with SARS-CoV-2 may contribute to disease severity, which can range from asymptomatic to severe with fatal outcome. Furthermore, the extent of host immune response activation may rely on underlying genetic predisposition for disease or protection. To address these questions, we performed immune profiling studies in mice with different genetic backgrounds - transgenic K18-hACE2 and wild-type 129S1 mice – subjected to reinfection with the severe disease-causing SARS-CoV-2 B.1.351 variant, 30 days after experimental milder BA.1 infection. BA.1 preinfection conferred protection against B.1.351-induced morbidity in K18-hACE2 mice but aggravated disease in 129S1 mice. We found that he cytokine/chemokine profile in B.1.351 re-infected 129S1mice is similar to that during severe SARS-CoV-2 infection in humans and is characterized by a much higher level of IL-10, IL-1β, IL-18 and IFN-γ , whereas in B.1.351 re-infected K18-hACE2 mice, the cytokine profile echoes the signature of naïve mice undergoing viral infection for the first time. Interestingly, the enhanced pathology observed in 129S1 mice upon reinfection cannot be attributed to a less efficient induction of adaptive immune responses to the initial BA.1 infection, as both K18-hACE2 and 129S1 mice exhibited similar B and T cell responses at 30 DPI against BA.1, with similar anti-BA.1 or B.1.351 spike-specific ELISA binding titers, levels of germinal center B-cells, and SARS-CoV-2-Spike specific tissue-resident T-cells. Long-term effects of BA.1 infection are associated with differential transcriptional changes in bronchoalveolar lavage-derived CD11c+ immune cells from K18-hACE2 and 129S1, with K18-hACE2 CD11c+ cells showing a strong antiviral defense gene expression profile whereas 129S1 CD11c+ cells showed a more pro-inflammatory response. In conclusion, initial infection with BA.1 induces cross-reactive adaptive immune responses in both K18-hACE2 and 129S1 mice, however the different disease outcome of reinfection seems to be driven by differential responses of CD11c+ cells in the alveolar space.
Project description:To explore the effects of SARS-CoV-2 proteins on expression of host genes in lung of infected mice, 4 groups of K18-hACE2 mice (4 mice per group) were mock-infected or infected cells with SARS-CoV-2 WT or its NPS1, or NSP15 mutants respectively.The mice were euthanized at 4 days post-infection to collect the lungs to isolate RNA for RNA sequencing.
Project description:We evaluate heterozygous transgenic mice expressing human ACE2 receptor driven by the epithelial cell promoter cytokeratin-18 promoter (K18-hACE2) as a model of SARS-CoV-2 infection. Intranasal inoculation of K18-hACE2 mice with SARS-CoV-2 results in high levels of infection in the lung parenchyma with spread to other organs.
Project description:Advanced age is associated with an increased susceptibility to Coronavirus Disease (COVID)-19 and more severe outcomes, although the underlying mechanisms are understudied. The lung endothelium is located next to infected epithelial cells and bystander inflammation may contribute to thromboinflammation and COVID-19-associated coagulopathy. Here, we investigated age-associated SARS-CoV-2 pathogenesis and endothelial inflammatory responses using humanized K18-hACE2 mice. Survival was reduced to 20% in aged mice (85-112 weeks) versus 50% in young mice (12-15 weeks) at 10 days post infection (dpi). Bulk RNA-sequencing of endothelial cells from mock and infected mice at 2dpi of both age groups (aged: 72-85 weeks; young: 15 weeks) showed substantially lower significant differentially regulated genes in infected aged mice than in young mice (712 versus 2294 genes). Viral recognition and anti-viral pathways such as RIG-I-like receptor signaling, NOD-like receptor signaling and interferon signaling were regulated in response to SARS-CoV-2. Young mice showed several fold higher interferon responses (Ifitm3, Ifit1, Isg15, Stat1) and interferon-induced chemokines (Cxcl10 and Cxcl11) than aged mice. Endothelial cells from infected young mice displayed elevated expression of chemokines (Cxcl9, Ccl2) and leukocyte adhesion markers (Icam1) underscoring that inflammation of lung endothelium during infection could facilitate leukocyte adhesion and thromboinflammation. TREM1 and acute phase response signaling were particularly prominent in endothelial cells from infected young mice. Immunohistochemistry was unable to detect viral protein in pulmonary endothelium. In conclusion, our data demonstrate that the early host response of the endothelium to SARS-CoV-2 infection declines with aging, which could be a potential contributor to disease severity.
Project description:We previously reported widespread differential expression of long non-protein-coding RNAs (ncRNAs) in response to virus infection. Here, we expanded the study through small RNA transcriptome sequencing analysis of the host response to both severe acute respiratory syndrome coronavirus (SARS-CoV) and influenza virus infections across four founder mouse strains of the Collaborative Cross, a recombinant inbred mouse resource for mapping complex traits. We observed differential expression of over 200 small RNAs of diverse classes during infection. A majority of identified microRNAs (miRNAs) showed divergent changes in expression across mouse strains with respect to SARS-CoV and influenza virus infections and responded differently to a highly pathogenic reconstructed 1918 virus compared to a minimally pathogenic seasonal influenza virus isolate. Novel insights into miRNA expression changes, including the association with pathogenic outcomes and large differences between in vivo and in vitro experimental systems, were further elucidated by a survey of selected miRNAs across diverse virus infections. The small RNAs identified also included many non-miRNA small RNAs, such as small nucleolar RNAs (snoRNAs), in addition to nonannotated small RNAs. An integrative sequencing analysis of both small RNAs and long transcripts from the same samples showed that the results revealing differential expression of miRNAs during infection were largely due to transcriptional regulation and that the predicted miRNA-mRNA network could modulate global host responses to virus infection in a combinatorial fashion. These findings represent the first integrated sequencing analysis of the response of host small RNAs to virus infection and show that small RNAs are an integrated component of complex networks involved in regulating the host response to infection. IMPORTANCE: Most studies examining the host transcriptional response to infection focus only on protein-coding genes. However, mammalian genomes transcribe many short and long non-protein-coding RNAs (ncRNAs). With the advent of deepsequencing technologies, systematic transcriptome analysis of the host response, including analysis of ncRNAs of different sizes, is now possible. Using this approach, we recently discovered widespread differential expression of host long (>200 nucleotide[nt]) ncRNAs in response to virus infection. Here, the samples described in the previous report were again used, but we sequenced another fraction of the transcriptome to study very short (about 20 to 30 nt) ncRNAs. We demonstrated that virus infection also altered expression of many short ncRNAs of diverse classes. Putting the results of the two studies together, we show that small RNAs may also play an important role in regulating the host response to virus infection. The small RNA transcriptome deep sequencing analysis was performed on lung samples from our previously published study (Unique signatures of long noncoding RNA expression in response to virus infection and altered innate immune signaling , X Peng, MBio. 2010 Oct 26;1(5). pii: e00206-10.). We infected four of the eight founder mouse strains used in generating the Collaborative Cross, a recombinant inbred mouse resource for mapping complex traits (41). These strains included 129S1/SvImJ (129/S1), WSB/EiJ (WSB), PWK/PhJ (PWK), and CAST/EiJ (CAST) mice. Ten-week-old mice were intranasally infected with phosphate-buffered saline (PBS) alone or with 1X10^5 PFU of mouse adapted severe acute respiratory syndrome coronavirus (SARS-CoV; rMA15), or 500 PFU of influenza A virus strain A/Pr/8/34 (H1N1; PR8). To match the previous whole-transcriptome analysis, we performed small RNA transcriptome sequencing analysis on the same eight samples from mice with SARS-CoV infections, including one SARS-CoV rMA15-infected mouse and one matched mock-infected mouse from each of the four strains at 2 days postinfection (dpi). In addition, we sequenced the small RNA transcriptome for 12 samples obtained from influenza virus infected mice, including two PR8-infected mice and one matched mockinfected mouse from each of the four strains at 2 dpi.