Metabolomic and lipidomic profiling to characterize the immunometabolic responses induced by perfluoroalkyl acids

Perfluoroalkyl acids (PFAAs) are extremely persistent chemicals that are widely distributed in the environment and general population, due to their high chemical stability and extensive use. In Hong Kong, PFAAs contaminations have been reported in various environmental matrices, food, and human blood samples, suggesting the exposure risks of Hong Kong population to PFAAs. Evidence from numerous epidemiological and laboratory studies indicates that exposure to PFAAs may induce immunosuppression effects, affecting both cell-mediated and humoral immunity. Up to date, the underlying immunotoxicity mechanisms of PFAAs are still not clearly understood. In recent years, accumulating evidence indicates that metabolic reprogramming governs the function of immune cells. PFAAs are known to activate peroxisome proliferator-activated receptors (PPARs), which have important roles in the regulation of lipid metabolism, fatty acid storage, and glucose metabolism. The possible interference of PFAAs in immune cell metabolism deserves further investigation for a better understanding of PFAAs associated immunotoxicity. Metabolomics and lipidomics techniques are particularly valuable for elucidating modes of action by determining exposure-associated metabolic/lipidomic profiles. In this proposal, mass spectrometry - based metabolomic and lipidomic profiling will be performed for the first time to characterize the metabolic perturbation in human immune cells associated with PFAAs exposure. Five PFAAs with different carbon chain length and functional groups will be selected to explore the potential relationship between structures - immunometabolic perturbation effects. Both liquid chromatography-mass spectrometry (LC/MS) and gas chromatography-mass spectrometry (GC/MS) will be used to enable a broad coverage of metabolites. Statistical data analysis including principal components analysis (PCA), partial least squares discriminant analysis (PLS-DA) and t-test will be applied to identify differential metabolites between control and exposure group. The metabolite set enrichment analysis and pathway analysis will be conducted to elucidate the disturbed metabolic pathways, and to facilitate the data interpretation. Moreover, the dysregulated metabolic pathways will be further validated and quantified using targeted profiling approach. The potential enzymatic targets associated with PFAAs exposure will be identified by determining the expression levels and activities of key enzymes involved in the perturbed metabolic pathways, using RT-PCR, western blotting assays and commercial kits, respectively. The successful completion of this project will shed new insights into the immunotoxicity related to PFAAs and lead to the discovery of potential enzyme targets for future management.