GDF15 and metabolic dysfunction-associated steatotic liver disease: It is well-established that circulating GDF15 levels increase in humans with MASLD and metabolic dysfunction-associated steatohepatitis (MASH) (Galuppo et al. 2022, Valenzuela-Vallejo et al. 2022, Asrih et al. 2023, L'Homme et al. 2024, Li et al. 2024a,b).