Association between complement C3 and the prevalence of metabolic-associated fatty liver disease in a Chinese population: a cross-sectional study

Abstract

OBJECTIVES: Recently studies demonstrated that adipose tissue can produce and release complement C3 and serum complement C3 levels were associated with diabetes mellitus, metabolic syndrome and non-alcoholic fatty liver disease (NAFLD). Thus, we plan to investigate the association of complement C3 levels and the presence of metabolic-associated fatty liver disease (MAFLD). DESIGN: Observational study with a cross-sectional sample. SETTING: This study surveyed 4729 participants in Zhejiang province, China. PARTICIPANTS: 55 participants were excluded for acute infection and 1001 participants were excluded for lack of ultrasonography diagnoses and complete or partial absence of laboratory tests. The final sample size was 3673 participants. OUTCOME MEASURES: Spearman correlation analysis was used to examine the correlations between complement C3 levels and variables. Binary logistic regression was carried out to evaluate the association between complement C3 levels and the presence of MAFLD after adjustment for demographic and biochemical variables. Mediation effects were used to explore whether insulin resistance (IR), hyperlipidaemia and obesity mediated the association between complement C3 and MAFLD. RESULTS: Participants with MAFLD had higher complement C3 levels and complement C3 levels were closely associated with body mass index, waist circumference, alanine aminotransferase, aspartate aminotransferase, γ-glutamyl transpeptidase and homoeostasis model assessment (HOMA)-IR. The presence of MAFLD increased with the increase of complement C3 levels and the presence of MAFLD were highest in the HOMA-IR ≥2.5 participants. We found the OR and Cl of standardised C3 for MAFLD was 1.333 (1.185-1.500), each 1 SD increase in C3 would increase the presence of MAFLD by 33.3%, and obesity partly mediated the effect of complement C3 on the presence of MAFLD. CONCLUSIONS: The present results suggest that complement C3 can be used as a risk factor for the presence of MAFLD after adjustment for confounding variables and obesity may partly mediate the effect of complement C3 on the presence of MAFLD.