Effect of chlordecone and mirex on the acute hepatotoxicity of acetaminophen in mice

Inverse association between plasma chlordecone concentrations and progression of alcoholic liver fibrosis: the role of liver metabolism

BACKGROUND AND AIMS

Chlordecone is a persistent organochlorinated insecticide, extensively used in the French West Indies and has been contaminating the population for more than thirty years. Its potentiation effect on hepatotoxic agents has been demonstrated in animal models. We investigated the relationship between environmental exposure to chlordecone and the progression of liver fibrosis.

METHODS

This study included 182 consecutive patients with chronic alcoholic hepatitis whose liver fibrosis was assessed using non-invasive methods. Measured plasma chlordecone concentrations at inclusion were used as surrogate of long-term exposure under steady-state conditions. As the pharmacokinetic processing of chlordecone is largely determined by the liver, we used a human physiologically based pharmacokinetic model to predict plausible changes in the steady-state blood chlordecone concentrations induced by liver fibrosis.

RESULTS

With a median follow-up of 27.1 years after the onset of alcohol consumption, we found a significant decrease in the risk of advanced liver fibrosis with increasing plasma chlordecone concentration (adjusted hazard ratio = 0.56; 95% confidence interval: 0.34-0.95 for the highest vs. lowest tertile, p = 0.04). Changes induced by liver fibrosis influenced the pharmacokinetic processing of chlordecone, resulting in substantial modifications in its steady-state blood concentrations.

CONCLUSION

According to this human model of coexposure to alcohol, reverse causality is the most plausible explanation of this inverse association between plasma chlordecone concentrations and progression of liver fibrosis. This study underlines the importance of considering the pharmacokinetic of environmental contaminants in epidemiological studies when biomarkers of exposure are used to investigate their own impact on the liver.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03373396.

Chlordecone potentiates auto-immune hepatitis and promotes brain entry of MHV3 during viral hepatitis in mouse models

Chlordecone is an organochlorine used in the 1970's as a pesticide in banana plantations. It has a long half-life in the soil and can potentially contaminate humans and animals through food. Chlordecone targets, and mainly accumulates in, the liver, leading to hepatomegaly and neurological signs in mammals. Chlordecone does not cause liver injuries or any inflammation by itself at low doses, but it can potentiate the hepatotoxic effects of other chemicals and drugs. We studied the impact of chlordecone on the progression of acute hepatitis in mouse models of co-exposure to chlordecone with Concanavalin A or murine hepatitis virus type 3. We examined the progression of these two types of hepatitis by measuring hepatic transaminase levels in the serum and inflammatory cells in the liver, liver histological studies. Amplified tremors presented in the MHV3- chlordecone mouse model had led us to study the expression of specific genes in the brain. We show that chlordecone amplifies the auto-immune hepatitis induced by Concanavalin A by increasing the number of liver NKT cells, which are involved in liver damage. Chlordecone also accelerated the death of mice infected by murine hepatitis virus and enhanced the entry of the virus into the cervical spinal cord in infected mice, leading to considerable neurological damage. In conclusion, chlordecone potentiates both the Concanavalin A-induced hepatitis and brain damage caused by an hepatotropic/neurotropic virus.

ATSDR evaluation of health effects of chemicals. II. Mirex and chlordecone: health effects, toxicokinetics, human exposure, and environmental fate

This document provides public health officials, physicians, toxicologists, and other interested individuals and groups with an overall perspective of the toxicology of mirex and chlordecone. It contains descriptions and evaluations of toxicological studies and epidemiological investigations and provides conclusions, where possible, on the relevance of toxicity and toxicokinetic data to public health. Additional substances will be profiled in a series of manuscripts to follow.

Amplified interactive toxicity of chemicals at nontoxic levels: mechanistic considerations and implications to public health

It is widely recognized that exposure to combinations or mixtures of chemicals may result in highly exaggerated toxicity even though the individual chemicals might not be toxic. Assessment of risk from exposure to combinations of chemicals requires the knowledge of the underlying mechanism(s). Dietary exposure to a nontoxic dose of chlordecone (CD; 10 ppm, 15 days) results in a 67-fold increase in lethality of an ordinarily inconsequential dose of CCl4 (100 microliters/kg, ip). Toxicity of closely related CHCl3 and BrCCl3 is also enhanced. Phenobarbital (PB, 225 ppm, 15 days) and mirex (10 ppm, 15 days) do not share the propensity of CD in this regard. Exposure to PB + CCl4 results in enhanced liver injury similar to that observed with CD, but the animals recover and survive in contrast to the greatly amplified lethality of CD + CCl4. Investigations have revealed that neither enhanced bioactivation of CCl4 nor increased lipid peroxidation offers a satisfactory explanation of these findings. Additional studies indicate that exposure to a low dose of CCl4 (100 microliters/kg, ip) results in limited injury, which is accompanied by a biphasic response of hepatocellular regeneration (6 and 36 hr) and tissue repair, which enables the animals to recover from injury. Exposure to CD + CCl4 results in suppressed tissue repair owing to an energy deficit in hepatocytes as a consequence of excessive intracellular influx of Ca2+ leading initially to a precipitous decline in glycogen and ultimately to hypoglycemia. Supplementation of cellular energy results in restoration of the tissue repair and complete recovery from the toxicity of CD + CCl4 combination. In contrast, only the early-phase hepatic tissue repair (6 hr) is affected in PB + CCl4 treatment, but this is adequately compensated for by a greater stimulation of tissue repair at 24 and 48 hr resulting in recovery from liver injury and animal survival. A wide variety of additional experimental evidence confirms the central role of stimulated tissue repair as a decisive determinant of the final outcome of liver injury inflicted by CCl4. For instance, a 35-fold greater CCl4 sensitivity of gerbils compared to rats is correlated with the very sluggish tissue repair in gerbils. These findings are consistent with a two-stage model of toxicity, where tissue injury is inflicted by the well described "mechanisms of toxicity," but the outcome of this injury is determined by whether or not sustainable tissue repair response accompanies this injury.(ABSTRACT TRUNCATED AT 400 WORDS)