# Integrated microbiome-metabolome analysis reveals multiorgan toxicity of 1-nitropyrene and the limited efficacy of ferroptosis inhibitor Fer-1 in rats

## TL;DR

Chronic exposure to 1-nitropyrene causes widespread metabolic and liver damage in rats, with limited benefits from a ferroptosis inhibitor.

## Contribution

This study is the first to integrate microbiome and metabolome data to reveal the multiorgan toxicity of 1-nitropyrene in rats.

## Key findings

- Chronic 1-NP exposure disrupts glucose homeostasis and causes NAFLD-like liver damage in rats.
- Exposure leads to gut microbiome dysbiosis and altered lipid and tryptophan metabolism.
- Ferroptosis inhibition with Fer-1 had limited efficacy in mitigating 1-NP-induced toxicity.

## Abstract

1-Nitropyrene (1-NP), a prevalent nitro-polycyclic aromatic hydrocarbon, is increasingly recognized as a potential metabolic disruptor, yet its systemic biological effects remain insufficiently characterized.

This study investigated the metabolic, immunological, hepatic, and microbiome alterations induced by chronic 1-NP exposure in rats and assessed whether ferroptosis inhibition via Fer-1 could mitigate these effects.

Although body weight was not significantly altered overall, high-dose exposure impaired growth from week 4. Exposed groups exhibited progressively elevated fasting blood glucose and impaired glucose tolerance, indicating significant disruption of glucose homeostasis. Serum biochemistry revealed dose-dependent reductions in HDL and total cholesterol, while histopathology confirmed hepatocyte ballooning, inflammation, and steatosis consistent with NAFLD-like progression. Hematological changes, including shifts in neutrophil and lymphocyte populations, suggested chronic inflammatory activation. Untargeted metabolomics identified extensive alterations in pathways related to glycolysis, tryptophan metabolism, glycerophospholipid metabolism, and ABC transporters. Gut microbiota analysis demonstrated reduced richness and significant compositional shifts, with functional predictions linking dysbiosis to xenobiotic degradation, lipid metabolism, and phosphotransferase systems. Integrated microbiome–metabolome analysis revealed coordinated disruptions in host–microbial metabolic networks. Fer-1 intervention modified specific metabolic and microbial signatures but did not substantially alleviate major toxic outcomes.

Overall, chronic 1-NP exposure causes widespread metabolic injury driven by combined effects on host metabolism, immune regulation, hepatic function, and gut microbial ecology. These findings highlight 1-NP as a potent environmental metabolic disruptor and underscore the need for further mechanistic studies to inform mitigation strategies.