PCSK9 rs11591147 R46L Loss-of-Function Variant Protects Against Liver Damage in Individuals with NAFLD

Background and Aims: The proprotein convertase subtilisin/kexin type 9 (PCSK9) plays a key role in cholesterol homeostasis, and its inhibition represents an effective therapy to lower LDL-C levels. In this study, we examined the impact of PCSK9 rs11591147 loss-of-function (LOF) variant on liver damage in a multicenter collection of patients at risk of nonalcoholic steatohepatitis (NASH), in clinical samples and experimental models. Methods: We considered 1,874 consecutive individuals at risk of NASH as determined by histology. The SNP rs11591147, encoding for the p.R46L variant of PCSK9, was genotyped by TaqMan assays. We also evaluated 1) PCSK9 mRNA hepatic expression in human liver, and 2) the impact of a NASH-inducing diet in mice with hepatic overexpression of human PCSK9. Results: Carriers of PCSK9 rs11591147 had lower circulating LDL-C levels and were protected against NAFLD (OR 0.42;95%C.I0.22-0.81;P=0.01), NASH (OR 0.39;95%C.I.0.20-0.75;P=0.005) and more severe fibrosis (OR 0.44;95%C.I.0.26-0.74;P=0.002) independently of clinical, metabolic and genetic confounding factors. PCSK9 hepatic expression was directly correlated with steatosis (P=0.03). Finally, liver-specific overexpression of human PCSK9 in mice drives NAFLD and fibrosis upon a dietary challenge. Conclusions: In individuals at risk, PCSK9 was induced with hepatic fat accumulation and PCSK9 rs11591147 LOF variant was protective against liver steatosis, NASH and fibrosis, suggesting PCSK9 inhibition may be a new therapeutic strategy to treat NASH. Funding Statement: This work was supported by project grant by the Swedish Research Council [Vetenskapsradet (VR), 2016-01527], the Swedish state under the Agreement between the Swedish government and the county councils (the ALF-agreement) [SU 2018-04276], the Novonordisk Foundation Grant for Excellence in Endocrinology [Excellence Project, 9321- 430], the Swedish Diabetes Foundation [DIA 2017-205], the Swedish Heart Lung Foundation [20120533], the Wallenberg Academy Fellows from the Knut and Alice Wallenberg Foundation [KAW 2017.0203]. LV was supported by MyFirst Grant AIRC n.16888, Ricerca Finalizzata Ministero della Salute [RF-2016-02364358], Ricerca corrente Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Fondazione Sviluppo Ca Granda [PR-0316], the European Union Programme Horizon 2020 [No. 777377]. Declaration of Interests: SR has been consulting for AMGEN, SANOFI, Astra Zeneca, Pfizer, AKCEA, Celgene, Medacorp, Foresite Labs, CAMP4 and received research grants from Astra Zeneca, AMGEN, SANOFI. SB, DK-P, A-CA, GP, MB-Y and DL are AstraZeneca employees. LV reports having received during the last 5 years speaking fees from MSD, Gilead, AlfaSigma, AbbVie, having served as a consultant of: Gilead, Pfizer, Astra Zeneca, Novo Nordisk, Diatech Pharmacogenetics and Intercept, and having received research grants from: Gilead. Ethics Approval Statement: The study was carried out in accordance with the principles of the Helsinki Declaration, and with local and national laws. Approval was obtained from Internal Review Boards and their Ethics Committees, and written informed consent for the study was obtained from all patients All animal experiments were performed with humane care and were approved by the Gothenburg Ethics Committee for Experimental Animals in Sweden. The holding facility has received full accreditation from the Association for Assessment and Accreditation of Laboratory Animal Care (AAALAC).