Biology subjects

Chew, K. Y.

Publications and source records attributed to Chew, K. Y..

9 recordsLinked to original sources

bioRxiv2026

IL-1β and TNF drive endothelial dysfunction and coagulopathy in acute COVID-19.

Vascular dysfunction and coagulopathy are hallmarks of severe COVID-19. How SARS-CoV-2 infection drives endothelial dysfunction, despite the virus not infecting or replicating in endothelial cells, remains controversial. Here, we used an in vitro co-culture model of the human pulmonary epithelial-endothelial cell barrier to investigate which inflammatory mediators drive endothelial dysfunction during SARS-CoV-2 infection. SARS-CoV-2 infection of primary human bronchial epithelial cells increased adjacent endothelial cell expression of the leukocyte adhesion marker ICAM-1, disrupted endothelial VE-cadherin junctions, promoted endothelial cell death, and promoted platelet adherence to gaps in the endothelial monolayers. Dexamethasone treatment rescued these dysregulated endothelial phenotypes in infected co-cultures, confirming that inflammatory signalling was the primary driver of SARS-CoV-2-induced endothelial dysfunction. Specifically, epithelial-derived TNF and IL-1{beta} promoted endothelial dysfunction, as inhibition of TNF or IL-1R signalling blocked SARS-CoV-2-induced endothelial dysfunction in co-cultures. SARS-CoV-2-infected wild-type mice, but not TNF, IL-1{beta}, or TNF/IL-1{beta}- deficient mice, displayed increased endothelial ICAM-1 expression, while an anti-IL-1{beta} monoclonal antibody prevented SARS-CoV-2-induced ICAM-1 expression and fibrin deposition in aged K18-ACE2 mice. Our data indicate that TNF and IL-1{beta} are the specific cytokines that drive multiple aspects of endothelial dysfunction during acute SARS-CoV-2 infection, and that inhibiting their signalling pathways may provide therapeutic benefit in preventing vascular complications of COVID-19.

cell biology↗

bioRxiv2026

AVE0991, a Mas receptor agonist, increases influenza and COVID-19 severity in vivo.

Dysregulation of the renin-angiotensin system (RAS) contributes to severe influenza and COVID-19, potentially via impaired ACE2/Ang-(1-7)/Mas receptor (MasR) signalling. AVE0991, an orally bioavailable MasR agonist, protects against non-infectious lung inflammation, but its effects in viral respiratory disease are unknown. We evaluated AVE0991 in human lung epithelial cells and murine models of influenza A virus (IAV) and SARS-CoV-2 infection. In vitro, AVE0991 suppressed cytokines IL-6 and TNF- to both IAV and SARS-CoV-2 and reduced IAV titres. Unexpectedly, in vivo treatment worsened disease. These findings highlight discordant in vitro and in vivo effects and underscore the need for careful evaluation of RAS-targeted therapies in acute viral infection.

microbiology↗

bioRxiv2024

Cardiovascular symptoms of PASC are associated with trace-level cytokines that affect the function of human pluripotent stem cell derived cardiomyocytes

Globally, over 65 million individuals are estimated to suffer from post-acute sequelae of COVID-19 (PASC). A large number of individuals living with PASC experience cardiovascular symptoms (i.e. chest pain and heart palpitations) (PASC-CVS). The role of chronic inflammation in these symptoms, in particular in individuals with symptoms persisting for >1 year after SARS-CoV-2 infection, remains to be clearly defined. In this cross-sectional study, blood samples were obtained from three different sites in Australia from individuals with i) a resolved SARS-CoV-2 infection (and no persistent symptoms i.e. Recovered), ii) individuals with prolonged PASC-CVS and iii) SARS-CoV-2 negative individuals. Individuals with PASC-CVS, relative to Recovered individuals, had a blood transcriptomic signature associated with inflammation. This was accompanied by elevated levels of pro-inflammatory cytokines (IL-12, IL-1{beta}, MCP-1 and IL-6) at approximately 18 months post-infection. These cytokines were present in trace amounts, such that they could only be detected with the use of novel nanotechnology. Importantly, these trace-level cytokines had a direct effect on the functionality of pluripotent stem cell derived cardiomyocytes in vitro. This effect was not observed in the presence of dexamethasone. Plasma proteomics demonstrated further differences between PASC-CVS and Recovered patients at approximately 18 months post-infection including enrichment of complement and coagulation associated proteins in those with prolonged cardiovascular symptoms. Together, these data provide a new insight into the role of chronic inflammation in PASC-CVS and present nanotechnology as a possible novel diagnostic approach for the condition.

microbiology↗

bioRxiv2022

Oxysterols drive inflammation via GPR183 during influenza virus and SARS-CoV-2 infection

RationaleSevere viral respiratory infections are often characterized by extensive myeloid cell infiltration and activation and persistent lung tissue injury. However, the immunological mechanisms driving excessive inflammation in the lung remain elusive. ObjectivesTo identify the mechanisms that drive immune cell recruitment in the lung during viral respiratory infections and identify novel drug targets to reduce inflammation and disease severity. MethodsPreclinical murine models of influenza virus and SARS-CoV-2 infection. ResultsOxidized cholesterols and the oxysterol-sensing receptor GPR183 were identified as drivers of monocyte-macrophage infiltration to the lung during influenza virus (IAV) and SARS-CoV-2 infections. Both IAV and SARS-CoV-2 infections upregulated the enzymes cholesterol 25-hydroxylase (CH25H) and cytochrome P450 family 7 subfamily member B1 (CYP7B1) in the lung, resulting in local production of the oxidized cholesterols 25-hydroxycholesterol and 7,25-dihydroxycholesterol (7,25-OHC). Loss-of-function mutation of GPR183, or treatment with a GPR183 antagonist, reduced macrophage infiltration and inflammatory cytokine production in the lungs of IAV- or SARS-CoV-2-infected mice. The GPR183 antagonist also significantly attenuated the severity of SARS-CoV-2 infection by reducing weight loss and viral loads. ConclusionThis study demonstrates that oxysterols drive inflammation in the lung and provides the first preclinical evidence for therapeutic benefit of targeting GPR183 during severe viral respiratory infections. Author SummaryViral infections trigger oxysterol production in the lung, attracting macrophages via GPR183. Blocking GPR183 reduced inflammation and disease severity in SARS-CoV-2 infection, making GPR183 a putative target for therapeutic intervention.

immunology↗

bioRxiv2022

The swan genome and transcriptome: its not all black and white

The Australian black swan (Cygnus atratus) is an iconic species with contrasting plumage to that of the closely related Northern Hemisphere white swans. The relative geographic isolation of the black swan may have resulted in a limited immune repertoire and increased susceptibility to infectious disease, notably infectious diseases from which Australia has been largely shielded. Indeed, unlike Mallard ducks and the mute swan (Cygnus olor), the black swan is extremely sensitive to severe highly pathogenic avian influenza (HPAI). Understanding this susceptibility has been impaired by the absence of any available swan genome and transcriptome information. Here, we generate the first chromosome-length annotated black and mute swan genomes annotated with transcriptome data, all using long-read based pipelines generated for vertebrate species. We used these genomes and transcriptomes, to show that unlike other wild waterfowl, black swans lack an expanded immune gene repertoire, lack a key viral pattern-recognition receptor in endothelial cells and mount a poorly controlled inflammatory response to HPAI. We also implicate genetic differences in SLC45A2 in the iconic plumage of the Australian black swan. Together, these data suggest that the immune system of the black swan is such that should any avian viral infection become established in its native habitat the survival of the black swan would be in significant peril.

genomics↗

bioRxiv2022

ACE2 is necessary for SARS-CoV-2 infection and sensing by macrophages but not sufficient for productive viral replication

Macrophages are key cellular contributors to COVID-19 pathogenesis. Whether SARS-CoV-2 can enter macrophages, replicate and release new viral progeny remains controversial. Similarly, whether macrophages need to sense replicating virus to drive cytokine release is also unclear. Macrophages are heterogeneous cells poised to respond to their local microenvironment, and accordingly, the SARS-CoV-2 entry receptor ACE2 is only present on a subset of macrophages at sites of human infection. Here, we use in vitro approaches to investigate how SARS-CoV-2 interacts with ACE2-negative and ACE2-positive human macrophages and determine how these macrophage populations sense and respond to SARS-CoV-2. We show that SARS-CoV-2 does not replicate within ACE2-negative human macrophages and does not induce pro-inflammatory cytokine expression. By contrast, ACE2 expression in human macrophages permits SARS-CoV-2 entry, replication, and virion release. ACE2-expressing macrophages sense replicating virus to trigger pro-inflammatory and anti-viral programs that limit virus release. These combined findings resolve several controversies regarding macrophage-SARS-CoV-2 interactions and identify a signaling circuit by which macrophages sense SARS-CoV-2 cell entry and respond by restricting viral replication. One sentence summaryLack of macrophage ACE2 expression precludes SARS-CoV-2 entry and sensing, while ACE2-expressing macrophages sense intramacrophage SARS-CoV-2 replication to induce rapid anti-viral responses that limit new virion release.

immunology↗

bioRxiv2022

COVID-19 vaccine booster induces a strong CD8+ T cell response against Omicron variant epitopes in HLA-A*02:01+ individuals

The >30 mutated residues in the Omicron spike protein have led to its rapid classification as a new SARS-CoV-2 variant of concern. As a result, Omicron may escape from the immune system, decreasing the protection provided by COVID-19 vaccines. Preliminary data shows a weaker neutralizing antibody response to Omicron compared to the ancestral SARS-CoV-2 virus, which can be increased after a booster vaccine. Here, we report that CD8+ T cells can recognize Omicron variant epitopes presented by HLA-A*02:01 in both COVID-19 recovered and vaccinated individuals, even 6 months after infection or vaccination. Additionally, the T cell response was stronger for Omicron variant epitopes after the vaccine booster. Altogether, T cells can recognize Omicron variants, especially in vaccinated individuals after the vaccine booster. One-Sentence SummaryCD8+ T cells response against Omicron variant epitopes is stronger after the vaccine booster.

immunology↗

bioRxiv2021

Pediatric nasal epithelial cells are less permissive to SARS-CoV-2 replication compared to adult cells

Children typically experience more mild symptoms of COVID-19 when compared to adults. There is a strong body of evidence that children are also less susceptible to SARS-CoV-2 infection with the ancestral viral isolate. However, the emergence of SARS-CoV-2 variants of concern (VOCs) has been associated with an increased number of pediatric infections. Whether this is the result of widespread adult vaccination or fundamental changes in the biology of SARS-CoV-2 remains to be determined. Here, we use primary nasal epithelial cells from children and adults, differentiated at an air-liquid interface to show that the ancestral SARS-CoV-2 replicates to significantly lower titers in the nasal epithelial cells of children compared to those of adults. This was associated with a heightened antiviral response to SARS-CoV-2 in the nasal epithelial cells of children. Importantly, the Delta variant also replicated to significantly lower titres in the nasal epithelial cells of children. This trend was markedly less pronounced in the case of Omicron. It is also striking to note that, at least in terms of viral RNA, Omicron replicated better in pediatric NECs compared to both Delta and the ancestral virus. Taken together, these data show that the nasal epithelium of children supports lower infection and replication of ancestral SARS-CoV-2, although this may be changing as the virus evolves.

microbiology↗

bioRxiv2021

Endothelial cells elicit a pro-inflammatory response to SARS-COV-2 without productive viral infection

ObjectivesThrombotic and microvascular complications are frequently seen in deceased COVID-19 patients. However, whether this is caused by direct viral infection of the endothelium or inflammation-induced endothelial activation remains highly contentious. MethodsHere, we use patient autopsy samples, primary human endothelial cells and an in vitro model of the pulmonary epithelial-endothelial cell barrier to show that primary human endothelial cells express very low levels the SARS-CoV-2 receptor ACE2 and the protease TMPRSS2. ResultsAccordingly, endothelial cells can only be infected when SARS-CoV-2 is present at very high concentrations. However, this is not a productive infection (i.e. no infectious virus is produced) and viral entry induces an inflammatory response. We also show that SARS-CoV-2 does not infect endothelial cells in 3D vessels under flow conditions. We further demonstrate that in a co-culture model endothelial cells are not infected with SARS-CoV-2. They do however sense and respond to infection in the adjacent epithelial cells, increasing ICAM-1 expression and releasing pro-inflammatory cytokines. ConclusionsTaken together, these data suggest that in vivo, endothelial cells are unlikely to be infected with SARS-CoV-2 and that infection is only likely to occur if the adjacent pulmonary epithelium is denuded (basolateral infection) or a high viral load is present in the blood (apical infection). In such a scenario, whilst SARS-CoV-2 infection of the endothelium can occur, it does not contribute to viral amplification. However, endothelial cells are still likely to play a key role in SARS-CoV-2 pathogenesis by sensing adjacent infection and mounting a pro-inflammatory response to SARS-CoV-2.

cell biology↗