Does inflammation increase oxidative stress and methylation demand?

Cytokine-driven oxidative stress

• Pro-inflammatory cytokines, including TNF-α, IL-1β, IFN-γ, and IL-6, directly induce reactive oxygen species (ROS) by upregulating NADPH oxidases (Nox1 and Nox2) and impairing mitochondrial complex I.
• This process initiates a feed-forward loop of mitochondrial electron leakage and lipid peroxidation, transforming membrane polyunsaturated fatty acids into reactive aldehydes like malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE).
• Nitric oxide from inducible nitric oxide synthase combines with superoxide to form peroxynitrite, further elevating systemic lipid peroxidation markers like F2-isoprostanes.

Methylation and transsulfuration redirection

• Under acute or moderate oxidative stress, cells prioritize glutathione (GSH) synthesis by activating the redox-sensitive enzyme cystathionine β-synthase (CBS) via S-glutathionylation and ferric heme oxidation.
• Activated CBS irreversibly commits homocysteine to the transsulfuration pathway to generate cysteine and glutathione, drawing it away from remethylation to methionine.
• This diversion of homocysteine depletes S-adenosylmethionine (SAM) pools, significantly increasing the overall metabolic demand on the methylation cycle to sustain essential epigenetic and cellular repair processes.

Bottom line

• Systemic inflammation directly drives oxidative stress, triggering an adaptive metabolic shift that prioritizes transsulfuration-dependent glutathione synthesis for redox defense at the direct expense of methyl donor conservation and methylation capacity.