Biology subjects

Sabberwal, P.

Publications and source records attributed to Sabberwal, P..

3 recordsLinked to original sources

bioRxiv2021

IFITM3 regulates virus-induced inflammatory cytokine production by titrating Nogo-B orchestration of TLR responses

Interferon induced transmembrane protein 3 (IFITM3) is an important viral restriction factor in viral pathogenesis that also exhibits poorly understood immune regulatory functions. Here, using human and mouse models, we demonstrate that IFITM3 regulates MyD88-dependent TLR-mediated cytokine production following dendritic cell exposure to cytomegalovirus (CMV), and this process limits viral pathogenesis in vivo. IFITM3 also restricted pro-inflammatory (IL-6) cytokine production in response to influenza. IFITM3 bound to and promoted ubiquitination and proteasomal degradation of the reticulon 4 isoform Nogo-B. We reveal that Nogo-B mediates TLR-dependent pro-inflammatory cytokine production and promotes viral pathogenesis in vivo, and this process involved alteration of TLR dynamics. The anti-inflammatory function of IFITM3 was intrinsically linked to its ability to regulate Nogo-B. Thus, we uncover Nogo-B as an unappreciated driver of viral pathogenesis and highlight a novel immune regulatory pathway where IFITM3 fine-tunes TLR responsiveness of myeloid cells to viral stimulation.

immunology↗

bioRxiv2021

ADNKA overcomes SARS-CoV2-mediated NK cell inhibition through non-spike antibodies

The outcome of infection is dependent on the ability of viruses to manipulate the infected cell to evade immunity, and the ability of the immune response to overcome this evasion. Understanding this process is key to understanding pathogenesis, genetic risk factors, and both natural and vaccine-induced immunity. SARS-CoV-2 antagonises the innate interferon response, but whether it manipulates innate cellular immunity is unclear. An unbiased proteomic analysis determined how cell surface protein expression is altered on SARS-CoV-2-infected lung epithelial cells, showing downregulation of activating NK ligands B7-H6, MICA, ULBP2, and Nectin1, with minimal effects on MHC-I. This correlated with a reduction in NK cell activation, identifying a novel mechanism by which SARS-CoV2 antagonises innate immunity. Later in the disease process, strong antibody-dependent NK cell activation (ADNKA) developed. These responses were sustained for at least 6 months in most patients, and led to high levels of pro-inflammatory cytokine production. Depletion of spike-specific antibodies confirmed their dominant role in neutralisation, but these antibodies played only a minor role in ADNKA compared to antibodies to other proteins, including ORF3a, Membrane, and Nucleocapsid. In contrast, ADNKA induced following vaccination was focussed solely on spike, was weaker than ADNKA following natural infection, and was not boosted by the second dose. These insights have important implications for understanding disease progression, vaccine efficacy, and vaccine design.

immunology↗

bioRxiv2020

Optimal CD8+ T-cell memory formation following subcutaneous cytomegalovirus infection requires virus replication but not early dendritic cell responses

Cytomegalovirus (CMV) induction of large frequencies of highly functional memory T-cells has attracted much interest in the utility of CMV-based vaccine vectors, with exciting preclinical data obtained in models of infectious diseases and cancer. However, pathogenesis of human CMV (HCMV) remains a concern. Attenuated CMV-based vectors, such as replication- or spread-deficient viruses potentially offer an alternative to fully replicating vectors. However, it is not well-understood how CMV attenuation impacts vector immunogenicity, in particularly when administered via relevant routes of immunization such as the skin. Herein we used the murine cytomegalovirus (MCMV) model to investigate the impact of vector attenuation on T-cell memory formation following subcutaneous administration. We found that the spread deficient virus ({Delta}gL-MCMV) was impaired in its ability to induce memory CD8+ T-cells reactive to some (M38, IE1) but not all (IE3) viral antigens. Impaired memory T-cell development was associated with a preferential and pronounced loss of polyfunctional (IFN-{gamma}+ TNF-+) T-cells, and was not rescued by increasing the dose of replication-defective MCMV. Finally, whilst vector attenuation reduced dendritic cell (DC) recruitment to skindraining lymph nodes, systematic depletion of multiple DC subsets during acute subcutaneous MCMV infection had a negligible impact on T-cell memory formation, implying that attenuated responses induced by replication-deficient vectors were likely not a consequence of impaired initial DC activation. Thus, overall, these data imply that the choice of antigen and/or cloning strategy of exogenous antigen in combination with the route of immunization may influence the ability of attenuated CMV vectors to induce robust functional T-cell memory.

immunology↗