PFAS exposure reshapes gut microbial metabolite profiles with downstream consequences for hepatocyte metabolism, providing new mechanistic insight into how PFAS may contribute to metabolic disorders.
Key Findings
Results
PFAS exposure altered the fecal metabolome in human colonic fermentations, particularly affecting pathways related to fatty acid, amino acid, vitamin, and mitochondrial metabolism.
An in vitro colon fermentation model was used to assess how PFAS-modified gut microbial metabolites affect human hepatocyte metabolism.
Pathway-level alterations were identified in fatty acid metabolism, amino acid metabolism, vitamin metabolism, and mitochondrial metabolism.
The study used a pilot study design, limiting generalizability but providing mechanistic insight.
Results
Fecal metabolomics from PFOA-exposed mice showed overlapping pathway-level alterations with the in vitro findings, including effects on fatty acid, bile acid, and steroid hormone metabolism.
An in vivo mouse exposure study was used to validate and support the biological relevance of the in vitro colon fermentation findings.
Overlapping pathways between mouse in vivo and human in vitro data included fatty acid metabolism, bile acid metabolism, and steroid hormone metabolism.
The convergence across model systems was used to support the translational relevance of the in vitro observations.
Results
Exposure of HepaRG hepatocytes to control fermentation extracts markedly altered lipid profiles, confirming that gut-derived metabolites actively regulate hepatic metabolism.
HepaRG cells (a human hepatocyte cell line) were exposed to fermentation extracts from control (non-PFAS-exposed) colonic fermentations.
Marked alterations in lipid profiles were observed, demonstrating that gut microbial metabolites per se have significant effects on hepatocyte lipid metabolism.
This finding establishes that the gut-liver metabolic axis is functionally active in the experimental system used.
Results
PFAS-exposed fermentation extracts induced distinct hepatocyte metabolic changes compared with PFAS-spiked control extracts, indicating effects driven by PFAS-modified microbial metabolites rather than direct PFAS carry-over.
A key experimental comparison was made between hepatocytes exposed to fermentation extracts from PFAS-treated fermentations versus hepatocytes exposed to control fermentation extracts directly spiked with PFAS.
The distinct metabolic responses between these two conditions indicate that the observed hepatocyte changes are attributable to PFAS-modified microbial metabolites, not residual PFAS in the extract.
This design allowed the researchers to attribute hepatocyte effects specifically to microbiota-mediated mechanisms rather than direct PFAS toxicity.
Results
PFAS-modified fermentation extracts decreased acyl-carnitines and increased L-carnitine in hepatocytes, consistent with altered fatty acid transport and mitochondrial β-oxidation.
Acyl-carnitines are markers of active mitochondrial fatty acid β-oxidation; their decrease alongside increased free L-carnitine suggests impaired fatty acid entry into mitochondria.
These changes were specifically observed in hepatocytes exposed to PFAS-modified fermentation extracts.
The pattern is consistent with disruption of fatty acid transport into mitochondria and reduced mitochondrial β-oxidation capacity.
Results
PFAS-modified fermentation extracts also altered bile acids, steroid metabolites, inosine, and sialic acid derivatives in hepatocytes.
Alterations in bile acids suggest disruption of bile acid signaling pathways.
Changes in steroid metabolites suggest endocrine-related metabolic disruption.
Alterations in inosine point to effects on purine metabolism, while changes in sialic acid derivatives suggest impacts on glycoprotein turnover and lipid-glucose homeostasis.
These findings indicate that PFAS-modified gut microbial metabolites affect multiple hepatic metabolic pathways simultaneously.
Methods
The study used a multi-model approach integrating in vitro human colon fermentation, in vivo mouse exposure, and in vitro human hepatocyte exposure to investigate PFAS effects on the gut-liver axis.
The in vitro colon fermentation model simulated how PFAS alter gut microbial metabolite production in humans.
The in vivo PFOA mouse model provided biological validation of the pathway-level findings.
HepaRG hepatocytes served as the human hepatic cell model to assess downstream metabolic consequences.
The authors describe this as a pilot study, noting inherent limitations in sample size and scope.
What This Means
This research suggests that common environmental chemicals called PFAS (per- and polyfluoroalkyl substances, sometimes called 'forever chemicals') can disrupt liver metabolism not only by directly affecting liver cells, but also indirectly by changing the types of metabolites produced by gut bacteria. The researchers used a laboratory model of human gut fermentation to show that exposing gut bacteria to PFAS changes the chemical signals those bacteria send to the liver. When liver cells were exposed to these PFAS-altered gut signals, their metabolism changed in ways distinct from what happens when liver cells are exposed to PFAS directly — confirming that the gut bacteria themselves play an important role in how PFAS harm the liver.
Specifically, the PFAS-altered gut signals caused liver cells to show signs of impaired fat burning (reduced acyl-carnitines and increased free L-carnitine), disrupted bile acid signaling, altered hormone-related metabolism, and changes in sugar and energy metabolism. These findings were supported by parallel experiments in mice exposed to PFOA (a common type of PFAS), which showed overlapping metabolic pathway disruptions. Together, the results suggest that PFAS exposure affects the gut-liver communication system in ways that could contribute to metabolic diseases such as fatty liver disease.
This pilot study provides new mechanistic understanding of how PFAS may promote metabolic disorders by reshaping the chemical environment that gut bacteria create. Because PFAS are ubiquitous in the environment and highly persistent in the body, understanding these indirect pathways of harm is important for assessing the full health risks of PFAS exposure. The authors note that this is a pilot study, so the findings need to be confirmed in larger studies before broader conclusions can be drawn.
Alijagic A, Castro-Alves V, Orešič T, Grau M, Vidal-Puig A, Prado S, et al.. (2026). PFAS exposure alters gut microbiota metabolites associated with hepatic metabolism: a pilot study.. Environment international. https://doi.org/10.1016/j.envint.2026.110463