CCL2 and metabolic dysfunction-associated steatotic liver disease: Our previous study showed that overexpression of PDE4D in liver increased hepatic and serum TGF-β1 levels, while the mRNA levels of TNFα, IL6, and CCL2 were not significantly changed [15], suggesting that TGF-β1 may be a potential link between PDE4D and NAFLD-associated CKD, but not other inflammatory cytokines.