Multi-omics approach to investigate the immune-cholangiocyte spatial relationship to stratify liver diseases

The involvement of proinflammatory cytokine IL17 (Interleukin-17) has been linked to multiple chronic inflammatory diseases, impairing wound healing and promoting fibrosis progression. The increase in IL17 level has been identified in a wide range of chronic liver diseases such as Non-Alcoholic Fatty Liver Disease (NAFLD), Primary Biliary Cholangitis (PBC), and Primary Sclerosing Cholangitis (PSC). Chronic liver disease is estimated to affect 800 million people worldwide with no effective anti-fibrotic treatments.
It is well known that IL17 promotes fibrogenesis through the activation of fibroblasts. However, the role of IL17 on epithelial cell fate and regeneration is less clear, especially with recent work suggesting that IL17 signalling primes epithelial proliferation in response to injury, fitting with preliminary data in our lab showing that IL17 signalling primes liver stem cell activation in response to liver injury. We have shown previously that cholangiocytes in the liver become regenerative liver stem cells in response to injury but the exact mechanisms which control this remains to be investigated. Furthermore, the emergence of the regenerative cholangiocytes tends to correlate with scar deposition around the regenerative niche which has a mixture of proliferating epithelial cells, immune cells, fibroblasts, and scar. It is unclear whether the emergence of IL17 cells and signalling in the liver is a protective mechanism or an indicator of poor prognosis in human diseases. Indeed, treatments involving pan-blockade of IL17 such as Secukinumab are on Phase 1/2 clinical trials for psoriasis, however, with the wide spectrum of chronic liver diseases and pathology, we wonder whether "one treatment fits all"?
Here, we aim to analyse published, publicly available single cell RNA (scRNA) sequencing datasets across a spectrum of liver diseases with variable aetiology such as cirrhosis, NAFLD, PSC and analyse whether IL17 has implications on regenerative cholangiocytes. Furthermore, we aim to spatially analyse the implications each disease has on IL17-mediated immune infiltrates in humans. This will stratify the role of IL17 and cholangiocytes across a spectrum of liver diseases and characterise the cholangiocytes and immune cells in different diseases transcriptionally and spatially, answering whether IL17 makes regenerative cholangiocytes pathogenic?
To complement the findings from scRNA sequencing datasets from clinical samples, we will use a mouse model where IL17 receptor is conditionally deleted in the cholangiocytes (Krt19CreERT2tdTomatoloxSTOPloxIL17Raflox) to inhibit IL17 signalling on cholangiocytes. Models of biliary or hepatocyte damage will be used on the transgenic mice in the presence or absence of cholangiocyte IL17 signalling. scRNA sequencing will be performed to investigate whether the absence of IL17 signalling on cholangiocytes alters the immune and regenerative landscape in the liver. Furthermore, this dataset will be used to match with the human datasets available publicly to identify matching cholangiocyte populations in human diseases. Qualitative & quantitative proteomics analysis will be performed on isolated murine cholangiocytes to identify pathogenic vs regenerative protein signatures.
The cholangiocyte specific IL17 inhibition strategy will show whether IL17 signalling differs in response to different injury mechanisms (i.e biliary vs hepatic), stratifying IL17 targeting treatment based on disease aetiology and complementing the pan-IL17 blockade strategies.
Dissecting the cell specific effect of IL17 on tissue regeneration and fibrosis, we aim to work towards the overarching aim to understand the role of IL17 signalling in chronic liver diseases - a friend or foe? More importantly, leading to potential targeted treatments for chronic liver disease based on aetiology.