Hyperactive complement driving inflam-ageing: a shortcut to cancer?

Background: We have developed a sophisticated complement C3 gain-of-function (GOF, C3D1115N/D1115N, or C3N/N) knock-in mouse. C3N/N mice develop the rare but devastating kidney disease atypical haemolytic uraemic syndrome (aHUS).

In new work, we have recently found that ~12 month old heterozygous (C3+/N) mice start to develop signs of liver injury, including increased steatosis, hepatic fibrosis, proliferation and apoptosis - consistent with non-alcoholic steatohepatitis (NASH).

C3+/N mice do not develop renal disease and breed normally, the liver and cancer phenotype develop naturally as mice age and the effects appear consistent with an inflammageing (PMID: 28608850). Notably, the C3+/N phenotype is reminiscent of that identified in factor H deficient mice (CFH-/-). CFH-/- mice have unchecked C3 activation and have been found to have a dysregulated adaptive immune system.

Interestingly, alterations in FH/ FHR protein expression can also be seen in patient derived samples as disease progresses Aim: Therefore, we will investigate the link between hyperactive C3, a dysregulated immune environment in the liver and the risk of progression to HCC.

We will confirm a link with Complement hyperactivity and inflammageing phenotypes, and define the increased risk of development of HCC.

Method: We will use colonies of C3+/N, CFH-/-, C3-/- and wild type mice and assess the effect of the GAN diet and age in combination with hyperactive C on HCC development.

We will establish if use oral complement therapeutics (comparing terminal or alternative pathway modifiers) are protective, given as a prophylactic treatment. We will in parallel compare findings in mice with those in our patient tissues.

Approved as part of the CRUK funded Hepatocellular Carcinoma Expediter network, we have access to formalin fixed paraffin embedded liver biopsy tissues from patients with simple steatosis, steatohepatitis and cirrhosis, as well as biopsies of MASLD associated HCC (well, moderate and poorly differentiated).

Immunohistochemical studies will define expression levels of FH, FHRs, iC3b/C3d, C5b-9, C5aR, C3aR as well as confirmation of previously reported changes in C4d, C3, C1q and MBL deposition.

How the results will be used: After further confirmation in additional models, we would seek to move towards clinical trials of anticomplement drugs that show the most efficacy in our models. Potential biomarkers would be confirmed in follow studies and additional cohorts.