Metabolomic Analysis Reveals the Mechanisms of Hepatotoxicity Induced by Aflatoxin M1 and Ochratoxin A.

Ya-Nan Gao,Nan Zheng,Jia-Qi Wang,Chen-Qing Wu

doi:10.3390/toxins14020141

Abstract

Aflatoxin M1 (AFM1) is the only toxin with the maximum residue limit in milk, and ochratoxin A (OTA) represents a common toxin in cereals foods. It is common to find the co-occurrence of these two toxins in the environment. However, the interactive effect of these toxins on hepatoxicity and underlying mechanisms is still unclear. The liver and serum metabolomics in mice exposed to individual AFM1 at 3.5 mg/kg b.w., OTA at 3.5 mg/kg b.w., and their combination for 35 days were conducted based on the UPLC-MS method in the present study. Subsequent metabolome on human hepatocellular liver carcinoma (Hep G2) cells was conducted to narrow down the key metabolites. The phenotypic results on liver weight and serum indicators, such as total bilirubin and glutamyltransferase, showed that the combined toxins had more serious adverse effects than an individual one, indicating that the combined AFM1 and OTA displayed synergistic effects on liver damage. Through the metabolic analysis in liver and serum, we found that (i) a synergistic effect was exerted in the combined toxins, because the number of differentially expressed metabolites on combination treatment was higher than the individual toxins, (ii) OTA played a dominant role in the hepatoxicity induced by the combination of AFM1, and OTA and (iii) lysophosphatidylcholines (LysoPCs), more especially, LysoPC (16:1), were identified as the metabolites most affected by AFM1 and OTA. These findings provided a new insight for identifying the potential biomarkers for the hepatoxicity of AFM1 and OTA.

Highlights

It has been reported that 25% of agricultural products are contaminated by various mycotoxins [1]
The liver weight was significantly decreased in the combination of Aflatoxin M1 (AFM1) and Ochratoxin A (OTA) group (p < 0.05, Figure 1C), while no significant difference was shown in the liver index (p > 0.05, Figure 1D)
The liver plays a vital role in metabolism and plays a key role in detoxification and excretion of exogenous chemicals [25]

Summary

Introduction

It has been reported that 25% of agricultural products are contaminated by various mycotoxins [1]. Mycotoxins occur in some certain indoor spaces such as agricultural product processing places and moldy buildings [2]. The high occurrence and contamination levels in milk and milk products were reported in South Asians and Africans as more and more attention has been aroused to monitor AFM1 levels [4]. The quality and safety of milk have improved, AFM1 contamination levels in milk samples occasionally exceeded the legal limit set by the EU [5–7]. OTA ranked first in the prevalence of cereals foods based on 9627 samples by meta-analysis [9]. Given that the co-existed mycotoxins may perform different interactive effects including additive, synergistic, or antagonistic effects, the potential risk of exposure to both AFM1 and OTA could not be underestimated

Methods

Results

Conclusion