Yaqiong Zhang

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-N-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.

Oxidative derivatives of triacylglycerols (ox-TGs), complex compounds formed during the thermal processing of lipid-rich foods, have not been thoroughly investigated in terms of their formation patterns, structure-toxicity relationships, or toxicological effects. In this study, the oxidation pattern of triolein was examined through a heating model reaction, and the resulting compounds were analyzed using high-resolution mass spectrometry. The toxicological and metabolic effects of ox-TGs were further assessed in a 28-day subacute mouse model. It was found that heating triolein at 180 °C for 24 h predominantly generated the epoxy and peroxy derivatives. After 28 days of in vivo exposure, ox-TGs disrupted hepatic functions (AST/ALT increased to 3.35 ± 1.11 in males) and lipid metabolism (TG, HDL-C, and LDL-C decreased to 0.83 ± 0.19, 1.18 ± 0.21, and 0.25 ± 0.07 mmol/L, respectively, in females) (P < 0.05), with distinct gender-based differences in toxicological and metabolic responses. These findings provided insights into the oxidation behavior of triacylglycerols during food processing and revealed the potential toxicity mechanisms and target organs of ox-TGs. This study contributed to a better understanding of ox-TG formation and toxicity, offering a scientific basis for strategies aimed at reducing their presence in food.

As a part of a continuous 90 day subchronic toxicology study, integrated metabolomic and transcriptomic approaches were applied to assess the metabolic network changes in the livers of Kunming mice exposed to three typical thermally induced food toxicants, including oxidative derivatives of triacylglycerols (ox-TGs), aldehydes, and 3-monochloropropane-1,2-diol esters (3-MCPDE), as well as their mixtures. Results showed lipid metabolic dysregulation through impaired purine metabolism, PPAR signaling, and bile acid metabolism. Ox-TGs emerged as the most hazardous compound, altering over 10 genes/enzymes. 3-MCPDE exhibited gender-specific effects, significantly upregulating fatty acid metabolism and gluconeogenesis genes in males. Interestingly, toxicant mixtures attenuated the adverse metabolic effects caused by individual compounds, demonstrating complex regulatory mechanisms in fatty acid biosynthesis and oxidation. The metabolomic and transcriptomic analyses conducted in this study revealed that combined exposure to multiple toxicants generated during lipid thermal processing may induce more complex toxicity effects than the simple additive effects of individual toxicants. Certain antagonistic effects were observed when comparing individual toxicants to their mixtures, highlighting the need for further mechanistic verifications in this area.

Oxidative derivatives of triacylglycerols (ox-TGs), aldehydes, and 3-monochloropropane-1,2-diol esters (3-MCPDE) were simultaneously evaluated in a 90-day subchronic study, focusing on biological indicators, biochemical indicators, and serum metabolomics as the first part of integrated toxicity and interactions. After 90 days of feeding Kunming mice, coexposure to combined toxicants significantly inhibited the trend of liver weight gain, reduced the levels of total bilirubin (TBIL) and direct bilirubin (DBIL), and decreased uric acid (UA) compared to individual toxicant exposure. A total of 21 and 31 biomarkers in female and male mice were identified, respectively. Co-exposure to combined toxicants might mitigate the changes in cytidine, CDP, dUMP, and dUDP involved in purine and pyrimidine metabolism caused by a single exposure, but exacerbate the changes in l-tryptophan, 5-hydroxy-l-tryptophan, and 5-hydroxyindoleacetic acid, which are involved in tryptophan metabolism. These results provided new insights into a comprehensive toxicity and interaction evaluation model of multiple combined toxicants in food.

In this work, the paraffin oil was first molecularly distilled into two mineral oil saturated hydrocarbons (MOSH) subfractions with their main carbon number range of C_20-30 (84.58%) and C_30-50 (89.65%), which were determined using a liquid chromatography-gas chromatography-flame ionization detector (LC-GC-FID) technique. Then, both female and male Fischer 344 (F344) rats were fed with the diets containing one of these two MOSH subfractions at the low (1.5 g/kg) or high dose (15 g/kg) for 6 months. It was found that the exposure of MOSH C_20-30 subfraction could result in a significant increase of spleen weight index (4.64 ± 0.18 mg/g for female and 3.79 ± 0.31 mg/g for male rats) (P < 0.05), and irregular shape of white medulla, and the macrophage infiltration in mesenteric lymph node for both female and male rats, especially for the 15 g/kg MOSH C_20-30-fed rats. Meanwhile, both MOSH C_20-30 and C_30-50 subfraction promoted inflammation and oxidative stress and had a negative effect on the immune function in both female and male rats. The metabolomics results further supported these observations, and indicated the down-regulation of cysteine and methionine metabolism, and glutathione metabolism pathway in female and male rats, respectively.