Lower hepatic CBS and PEMT expression in advanced NAFLD: inferencing strategies to lower homocysteine with a mathematical model

Aim: Hepatic homocysteine (Hcy) accumulation promotes inflammation and fibrosis in experimental nonalcoholic fatty liver disease (NAFLD), while vitamin B12 and folate reduce hepatic Hcy and protect animals from nonalcoholic steatohepatitis. This suggests clinical implications for preventing/treating patients with NAFLD. Given the known sex-specific regulation of one-carbon metabolism (OCM), the response to various OCM cofactors may vary by sex and reproductive status. We aimed to strategize an effective Hcy-lowering treatment in broader NAFLD patients while discerning disparities in treatment responses. Methods: We analyzed existing hepatic microarray data relevant to Hcy metabolism with clinical and histologic data from patients with NAFLD (N = 82), while considering potential age/sex disparities. Additionally, we performed computer simulation analyses using a mathematical model of OCM to predict hepatic Hcy-lowering effects of OCM cofactors by sex. Results: Of 82 patients with NAFLD, 98% had at least one metabolic feature [i.e., metabolic dysfunction-associated steatotic liver disease (MASLD)]. Lower hepatic gene expressions of cystathionine-beta synthase (CBS ) and phosphatidyl- ethanolamine N-methyltransferase (PEMT ) were associated with more severe fibrosis in NAFLD, while sub-analysis suggested possible variations by age and sex. The simulation analysis demonstrated sex differences in the Hcy-lowering effects of the OCM cofactors (vitamins B6 and B12, folate, and betaine), with the combination of these cofactors consistently showing the maximum Hcy-lowering effect in both sexes. Conclusion: We theorize that the combination of OCM cofactors would maximize Hcy-lowering effects in the broader MASLD population. Our findings also underscore the importance of considering sex and age in designing future studies on homocysteine metabolism.