WEHI PhD Completion Seminar hosted by Associate Professor James Vince

Jiyi Pang

PhD Student – Vince Laboratory, Inflammation division – Infection, Inflammation & Immunity Theme, WEHI

Cytokine Synergy and iNOS: Unveiling Mechanisms of Cell Death in Inflammatory Bowel Disease and SARS-CoV-2 Infection

Davis Auditorium

Join via SLIDO enter code #WEHIphdcompletion

Including Q&A session

Followed by refreshments in Tapestry Lounge

The abnormal activation of programmed cell death is associated with diverse disease states, including Inflammatory bowel disease (IBD) and SARS-CoV-2 infections. The molecular machinery underlying cell death in these conditions is poorly defined, although inducible nitric oxide synthase (iNOS) and its generation of of the free radical nitric oxide (NO) is a common factor previously implicated in both IBD and COVID-19.

During my PhD, I investigated how iNOS contributes to programmed cell death in the context of IBD and SARS-CoV-2 infections. I first confirmed the increase of programmed cell death in IBD by observing the apoptotic caspase-3 processing in inflamed IBD intestinal biopsies, which correlated with the enrichment of interferon gamma (IFNγ) and TNF pathways. Utilizing whole genome RNA sequencing of human colonic organoids, I discovered that IFNγ upregulated genes involved in multiple cell death pathways, as well as the expression of inducible nitric oxide synthetase (iNOS). Co-stimulation with IFNγ and TNF strongly induced iNOS expression and NO generation, which correlated with cell death. Investigations using western blotting, targeted cell death inhibitors, and CRISPR/Cas9 gene editing uncovered distinct iNOS-dependent and iNOS-independent cell death mechanisms across different intestinal cell types, which also involves BCL-2 family proteins.

Similar to IBD, the induction of iNOS expression was also identified in lung tissue following SARS-CoV-2 infection. In vivo mouse studies were undertaken, which defined how iNOS levels dictate COVID-19 disease severity in an age-dependent manner. Further work investigated how this iNOS and age-dependent phenotype reflected the role of iNOS in driving cell death of lung immune cells.   

Collectively, my PhD provide a new framework for how iNOS expression can drive programmed cell death in both infectious and inflammatory conditions, with my data also suggesting that this impacts disease pathogenesis. 

All welcome!