Integrated Metabolomics and Proteomics Reveal Gender-Dependent Immunotoxicity Mechanisms of Mineral Oil Saturated Hydrocarbons in Fischer 344 Rats

A 6 month subchronic toxicity study demonstrated that exposure to the mineral oil saturated hydrocarbon (MOSH) subfraction (predominant carbon range C_20-30) induced dose- and gender-dependent immunometabolic disruption in Fischer 344 rats. Both low- (1.5 g/kg) and high-dose (15 g/kg) exposure significantly reduced the arterial blood CD4⁺/CD8⁺ T-cell ratio in both genders (female: 1.85 ± 0.40 and 1.27 ± 0.13 vs 3.14 ± 0.20 in controls; male: 1.04 ± 0.39 and 0.95 ± 0.26 vs 4.38 ± 0.54 in controls), indicating concomitant immune dysregulation and inflammation. Integrated metabolomic and proteomic analyses of the spleen elucidated distinct gender-associated responses. Females exhibited upregulated purine metabolism, evidenced by elevated purine intermediates (5-aminoimidazole ribonucleotide and 5'-phosphoribosyl-<i>N</i>-formylglycinamide) and increased expression of proteins involved in de novo synthesis (PRPS1, GART, and ADSS2) and salvage pathways (adenylate kinase 3, guanine deaminase, and GMPR). In contrast, males displayed a dual pathophysiological pattern characterized by systemic purine activation alongside suppressed mitochondrial energy metabolism (PDHB, HK1, and ACSS1), impaired glutathione homeostasis (GSR and GSTA4), and downregulated heme metabolism (ALAS2, HMBS, CPOX, FECH, HMOX1, and CP). These alterations were consistently more pronounced in the high-dose group. The findings reveal gender-specific immunometabolic toxicity of the MOSH C_20-30 subfraction, highlighting the necessity of incorporating gender-specific effects and immunometabolic endpoints in future risk assessment of MOSH exposure.