Plasmatic concentration of organochlorine lindane acts as metabolic disruptors in HepG2 liver cell line by inducing mitochondrial disorder

The mode of action of different organochlorine pesticides families in mammalians

Organochlorine pesticides (OCPs) show differences in their chemical structure, mechanism of toxicity, and target organisms. However, OCPs also have some common characteristics such as high persistence in the environment, bioaccumulation, and toxicity which lead to health issues. Nowadays, the toxicity of OCPs is well known, but we still do not know all the specific molecular mechanisms leading to their toxicity in mammalians. Therefore, this review aims to collect data about the mode of action of various classes of OCPs, highlighting their differences and common behavioural reactions in the human and animal body. To discuss the OCPs molecular pathways and fate in different systems of the body, three organochlorine insecticides were selected (Dichlorodiphenyltrichloroethane, Hexachlorocyclohexane and Chlordecone), regarding to their widespread use, with consequent effects on the ecosystem and human health. Their common biological responses at the molecular scale and their different interactions in human and animal bodies were highlighted and presented.

Removal of lindane in liquid culture using soil bacteria and toxicity assessment in human skin fibroblast and HCT116 cell lines

The development of effective measures for the remediation of lindane contaminated sites is the need of the hour. In this study, a potent lindane degrading bacteria, identified as Rhodococcus rhodochrous NITDBS9 was isolated from an agricultural field of Odisha that could utilize up to 87% of 100 mg L^-1 lindane when grown under liquid culture conditions in mineral salt media in 10 days. The bacteria could produce biofilm in lindane-containing media. Rhodococcus rhodochrous NITDBS9 was further characterized for its plant growth-promoting properties and it was found that the bacteria showed abilities for phytohormone, ammonia and biosurfactant production, etc. This could be beneficial for the bioremediation and improvement of crop production in contaminated sites. Ecotoxicity studies carried out for lindane, and its degradation products in mung bean and mustard seeds showed a reduction in toxicity of lindane after treatment with NITDBS9. NITDBS9 was used with a previously isolated potent lindane degrading strain Paracoccus sp. NITDBR1 in a dual mixed culture for the enhanced removal of lindane in the liquid system i.e. up to 93% in 10 days. Cytotoxicity studies were conducted with lindane before and after treatment with the single and dual mixed cultures on human skin fibroblast and HCT116 cell lines. They revealed a significant reduction in toxicity of lindane after it was bioremediated with the single and dual mixed cultures. Therefore, our proposed strategy could be efficiently used for the detoxification of the lindane-contaminated system, and further work should be done to study the use of these cultures in the contaminated soil system.

Lindane removal in contaminated soil by defined microbial consortia and evaluation of its effectiveness by bioassays and cytotoxicity studies

Lindane contamination in different environmental matrices has been a global concern for long. Bacterial consortia consisting of Paracoccus sp. NITDBR1, Rhodococcus rhodochrous NITDBS9, Ochrobactrum sp. NITDBR3, NITDBR4 and NITDBR5 were used for the bioremediation of soil artificially contaminated with lindane. The bacteria, Paracoccus sp. NITDBR1 and Rhodococcus rhodochrous NITDBS9, have been selected based on their lindane degrading capacity in liquid culture conditions (~80-90 %). The remaining three bacteria were chosen for their auxiliary properties for plant growth promotion, such as nitrogen fixation, phosphate solubilization, indole-3-acetic acid production and ammonia production under in vitro conditions. In this study, market wastes, mainly vegetable wastes, were added to the soil as a biostimulant to form a biomixture for assisting the degradation of lindane by bioaugmentation. Residual lindane was measured at regular intervals of 7 days to monitor the biodegradation process. It was observed that the consortium could degrade ~80% of 50 mg kg^-1 lindane in soil which was further increased in the biomixture after six weeks of incubation. Bioassays performed on plant seeds and cytotoxicity studies performed on human skin fibroblast and HCT116 cell lines revealed that the groups contaminated with lindane and treated with the bacterial consortium showed lower toxicity than their respective controls without any bacteria. Hence, the use of both pesticide degrading and plant growth-promoting bacteria in a consortium can be a promising strategy for improved bioremediation against chemical pesticides, particularly in soil and agricultural fields, simultaneously enhancing crop productivity in those contaminated soil.

Differential mitochondrial dysregulation by exposure to individual organochlorine pesticides (OCPs) and their mixture in zebrafish embryos

Organochlorine pesticides (OCPs) have been reported to cause mitochondrial dysfunction. However, most studies reported its mitochondrial toxicity with respect to a single form, which is far from the environmentally relevant conditions. In this study, we exposed zebrafish embryos to five OCPs: chlordane, heptachlor, p,p'-dichlorodiphenyltrichloroethane (p,p'-DDT), β-hexachlorocyclohexane (β-HCH), and hexachlorobenzene (HCB), as well as an equal ratio mixture of these OCPs. We evaluated mitochondrial function, including oxygen consumption, the activity of mitochondrial complexes, antioxidant reactions, and expression of genes involved in mitochondrial metabolism. Oxygen consumption rate was reduced by exposure to chlordane, and β-HCH, linking to the increased activity of specific mitochondrial complex I and III, and decreased GSH level. We found that these mitochondrial dysfunctions were more significant in the exposure to the OCP mixture than the individual OCPs. On the mRNA transcription level, the individual OCPs mainly dysregulated the metabolic cycle (i.e., cs and acadm), whereas the OCP mixture disrupted the genes related to mitochondrial oxidative phosphorylation (i.e., sdha). Consequently, we demonstrate that the OCP mixture disrupts mitochondrial metabolism by a different molecular mechanism than the individual OCPs, which warrants further study to evaluate mitochondrial dysregulation by chronic exposure to the OCP mixture.

PSTi8 with metformin ameliorates perimenopause induced steatohepatitis associated ER stress by regulating SIRT-1/SREBP-1c axis

Aims

Hepatic steatosis in women confronting menopause is the manifestation of substantial fructose consumption and forms a positive feedback loop to develop endoplasmic reticulum (ER) stress. Previously pancreastatin inhibitor peptide-8 (PSTi8) and Metformin (Met) combination effectively ameliorated hepatic lipid accumulation in high fructose diet (HFrD) fed diabetic mice models at reduced doses. Moreover, SIRT-1 plays a crucial role in the regulation of SREBP-1c. Hence we hypothesized that Met and PSTi8 in combination (at therapeutic lower doses) could mitigate hepatic steatosis linked ER stress by activating SIRT-1 and precluding SREBP-1c in HFrD fed 4-Vinylcyclohexenediepoxide (HVCD) induced perimenopausal rats.

Main methods

HVCD rats were fed HFrD for 12 weeks, accompanied by 14 days of treatment with Met, PSTi8, and combination. We confirmed model establishment by estrus cycle study, estradiol level, and intraperitoneal glucose tolerance test. Plasma lipid profile and liver function were determined. Also, mRNA and protein expressions were examined. Moreover, distribution of SIRT-1 and SREBP-1c was detected in HepG2 cells by immunofluorescence staining.

Key findings

HVCD group displayed augmented insulin resistance (IR), lipogenesis, and ER stress in the liver. Combination therapy improved the estrus cyclicity, estradiol, and lipid profile of HVCD rats. Met and PSTi8 combination reduced hepatic SREBP-1c and triggered SIRT-1 expression in high fructose-induced insulin-resistant HepG2 cells; consequently, combination therapy attenuated ER stress.

Significance

Succinctly, present research promotes impetus concerning the remedial impact of Met with PSTi8 at lower therapeutic doses to ameliorate hepatic IR, steatosis, and associated ER stress by revamping the SIRT-1/SREBP-1c axis in perimenopausal rats.

Combination of Pancreastatin inhibitor PSTi8 with metformin inhibits Fetuin-A in type 2 diabetic mice

In the preceding study, we delineated that high-fat diet (HFD) consumption in mice increases the circulatory level of pancreastatin (PST), which additionally enhances the free fatty acid (FFA) concentration in circulation. Consequently, the aggravated FFA activates Fetuin-A, which facilitates hepatic lipid accumulation, insulin resistance (IR), and culminates in type 2 diabetes (T2D). Metformin (Met) is a widely known first-line drug for the treatment of T2D. We previously unveiled PSTi8, an inhibitor of PST, comprising antidiabetic property. Hence, we hypothesized that combination therapy of Met and PSTi8, at reduced therapeutic doses, would mitigate HFD-induced IR by inhibiting hepatic Fetuin-A in mice model of T2D. C57BL/6 mice were fed HFD for 12 weeks, followed by treatment with Met, PSTi8, and its combination for 10 days. Glucose and insulin tolerance tests were conducted. Circulatory levels of PST, Fetuin-A, and lipid markers were determined. Also, the mRNA and protein expression of Fetuin-A was assessed by qPCR, western blotting, and immunofluorescence. Moreover, the energy expenditure was measured by comprehensive laboratory animal monitoring system (CLAMS). Combination therapy displayed improved PST, Fetuin-A, and lipid profile in plasma. We also found reduced hepatic Fetuin-A, which reduced inhibitory phosphorylation of IRS and increased phosphorylation of AKT. Consequently, ameliorated hepatic lipogenesis, gluconeogenesis, and inflammation. Also, combination treatment attenuated Fetuin-A expression, lipid accumulation, and glucose production in palmitate-induced HepG2 cells. Altogether current study promulgates the beneficial effect of combination therapy of Met and PSTi8 (comparable to alone higher therapeutic doses) to ameliorate Fetuin-A activation, hepatic lipid accumulation, insulin resistance, and associated progressive pathophysiological alterations in T2D.

Cellular responses of normal (HL-7702) and cancerous (HepG2) hepatic cells to dust extract exposure

Cancerous human liver cell line has been used to test the hepatic toxicity of indoor dust, showing its organic extract decreases cell viability. However, little is known about its impact on normal human liver cell line. In the present study, we compared the cellular responses between carcinoma cell line (HepG2) and normal cell line (HL-7702) after exposing to 10-640 μg/100 μL organic dust extract for 24 h. The dust extract caused cytotoxicity, oxidative damage, inflammatory response and loss of mitochondrial transmembrane potential (MMP) in both cells. The inhibition of cell viability in HL-7702 cells was stronger than that in HepG2 cells, with HL-7702 cells having lower LC₅₀. Higher production of oxidative stress, more loss of MMP and stronger suppression of antioxidant enzymes mRNA level occurred in HepG2 cells, while mRNA expression and hepcidin secretion were enhanced in HL-7702 cells at 40/100 μL, indicating the dust extract probably perturbed their liver Fe homeostasis. Our data showed considerable differences in cellular responses between normal and cancerous cell lines. To obtain accurate data, normal hepatocytes should be employed as they better match with the in vivo tissue than cancerous cell lines.

Contribution of Persistent Organic Pollutant Exposure to the Adipose Tissue Oxidative Microenvironment in an Adult Cohort: A Multipollutant Approach

Despite growing in vitro and in vivo evidence of the putative role of persistent organic pollutants (POPs) in the induction of oxidative damage in cell structures, this issue has been poorly addressed from an epidemiologic perspective. The aim of this study was to explore associations between adipose tissue POP concentrations and the in situ oxidative microenvironment. A cross-sectional study was conducted in a subsample (n = 271) of a previously established cohort, quantifying levels of eight POPs and four groups of oxidative stress biomarkers in adipose tissue. Associations were explored using multivariate linear regression analyses adjusted for potential confounders. We assessed the combined effect of POPs on oxidative stress/glutathione system biomarkers using weighted quantile sum regression (WQS). Increased concentrations of p,p'-DDE, HCB, β-HCH, dicofol, and PCBs (congeners -138, -153, and -180) were predominantly associated with higher lipid peroxidation (TBARS) [exp(β) = 1.09-1.78, p < 0.01-0.04)] and SOD activity [exp(β) = 1.13-1.48, p < 0.01-0.05)] levels. However, only a few associations were observed with glutathione system biomarkers, e.g., PCB-180 with total glutathione [exp(β) = 1.98, p = 0.03]. The WQS index was found to be positively associated with SOD activity, and PCB-138, PCB-180, and β-HCH were the main contributors to the index. Likewise, the WQS index was positively associated with TBARS levels, with the three PCBs acting as the main contributors. This is the first epidemiological evidence of the putative disruption by POPs of the adipose tissue oxidative microenvironment. Our results indicate that POP exposure may enhance alternative pathways to the glutathione detoxification route, which might result in tissue damage. Further research is warranted to fully elucidate the potential health implications.

Potential hepatic toxicity of buprofezin at sublethal concentrations: ROS-mediated conversion of energy metabolism

Buprofezin is known for its broad-spectrum action and environmental safety. The popularity of buprofezin has raised concerns about its potentially adverse effects on human health and risk to the environment. In this study, we first identified the liver as one of the major organs in which buprofezin accumulated, and we detected a severe oxidative stress response. Next, we demonstrated that sublethal concentrations of buprofezin promoted the conversion of energy metabolism from the aerobic tricarboxylic acid (TCA) cycle and oxidative phosphorylation to anaerobic glycolysis. Importantly, reactive oxygen species (ROS) generation partially accounted for the shunting of the energy metabolism through the buprofezin-mediated inhibition of cytochrome c oxidase activity. ROS directly perturbed the activities of several key TCA cycle enzymes, stimulated glycolysis, and indirectly disturbed the activity of the respiratory chain complex by altering mitochondrial DNA (mtDNA). These findings clarify the potential mechanisms of buprofezin toxicity and provide biomarkers for buprofezin-mediated hepatotoxicity at sublethal concentrations.

Human Elimination of Organochlorine Pesticides: Blood, Urine, and Sweat Study

Background. Many individuals have been exposed to organochlorinated pesticides (OCPs) through food, water, air, dermal exposure, and/or vertical transmission. Due to enterohepatic reabsorption and affinity to adipose tissue, OCPs are not efficiently eliminated from the human body and may accrue in tissues. Many epidemiological studies demonstrate significant exposure-disease relationships suggesting OCPs can alter metabolic function and potentially lead to illness. There is limited study of interventions to facilitate OCP elimination from the human body. This study explored the efficacy of induced perspiration as a means to eliminate OCPs. Methods. Blood, urine, and sweat (BUS) were collected from 20 individuals. Analysis of 23 OCPs was performed using dual-column gas chromatography with electron-capture detectors. Results. Various OCPs and metabolites, including DDT, DDE, methoxychlor, endrin, and endosulfan sulfate, were excreted into perspiration. Generally, sweat samples showed more frequent OCP detection than serum or urine analysis. Many OCPs were not readily detected in blood testing while still being excreted and identified in sweat. No direct correlation was found among OCP concentrations in the blood, urine, or sweat compartments. Conclusions. Sweat analysis may be useful in detecting some accrued OCPs not found in regular serum testing. Induced perspiration may be a viable clinical tool for eliminating some OCPs.

Assembly defects induce oxidative stress in inherited mitochondrial complex I deficiency

Complex I (CI) deficiency is the most common respiratory chain defect representing more than 30% of mitochondrial diseases. CI is an L-shaped multi-subunit complex with a peripheral arm protruding into the mitochondrial matrix and a membrane arm. CI sequentially assembled into main assembly intermediates: the P (pumping), Q (Quinone) and N (NADH dehydrogenase) modules. In this study, we analyzed 11 fibroblast cell lines derived from patients with inherited CI deficiency resulting from mutations in the nuclear or mitochondrial DNA and impacting these different modules. In patient cells carrying a mutation located in the matrix arm of CI, blue native-polyacrylamide gel electrophoresis (BN-PAGE) revealed a significant reduction of fully assembled CI enzyme and an accumulation of intermediates of the N module. In these cell lines with an assembly defect, NADH dehydrogenase activity was partly functional, even though CI was not fully assembled. We further demonstrated that this functional N module was responsible for ROS production through the reduced flavin mononucleotide. Due to the assembly defect, the FMN site was not re-oxidized leading to a significant oxidative stress in cell lines with an assembly defect. These findings not only highlight the relationship between CI assembly and oxidative stress, but also show the suitability of BN-PAGE analysis in evaluating the consequences of CI dysfunction. Moreover, these data suggest that the use of antioxidants may be particularly relevant for patients displaying a CI assembly defect.

Alterações nos marcadores hepáticos decorrentes da exposição ambiental a organoclorados no Brasil

Objetivos:Estimar a magnitude da associação entre a exposição a resíduos de pesticidas organoclorados (OC) e alterações de marcadores hepáticos.Método: Estudo seccional conduzido em população exposta a OC residente em Cidade dos Meninos,Duque de Caxias (RJ), Brasil (n=354). Foram calculadas as taxas de alterações dos marcadores hepáticos (Alanina aminotransferase (ALT), Aspartato aminotransferase (AST), fosfatase alcalina, gama glutamil transpeptidase (GGT) e albumina) e, em seguida, por meio de regressão logística binária não condicional, foi estimada a associação entre a presença ou não de alterações e os grupos de exposição, criados com base na exposição a alimentos, solo e água contaminados no local. Razões de chance (Odds ratio- OR) brutas e ajustadas para os grupos de exposição e para os fatores de confusão e seus respectivos intervalos de confiança (IC95%) foram obtidos.Resultados:Após ajuste pela regressão logística, os resultados do presente estudo apontam para nenhuma associação entre alterações em enzimas hepáticas e a exposição a OC.Conclusão:O achado sugere que o metabolismo que envolve a distribuição e a biotransformação de OC no organismo não envolve toxicidade direta ao fígado.

Purinergic control of AMPK activation by ATP released through connexin 43 hemichannels - pivotal roles in hemichannel-mediated cell injury

Connexin hemichannels regulate many cell functions. However, the molecular mechanisms involved remain elusive. Hemichannel opening causes loss of ATP, we therefore speculated a potential role for AMPK in the biological actions of hemichannels. Activation of hemichannels by removal of extracellular Ca(2+) led to an efflux of ATP and a weak activation of AMPK. Unexpectedly, dysfunction of hemichannels markedly potentiated AMPK activation, which was reproduced by promotion of extracellular ATP degradation or inhibition of P2 purinoceptors but counteracted by exogenous ATP. Further analysis revealed that ATP induced a purinoceptor-dependent activation of Akt and mTOR. Suppression of Akt or mTOR augmented AMPK activation, whereas activation of Akt by transfection of cells with myristoylated Akt, a constitutively active form of Akt, abolished AMPK activation. In a pathological model of hemichannel opening triggered by Cd(2+), disclosure of hemichannels similarly enhanced AMPK activity, which protected cells from Cd(2+)-induced cell injury through suppression of mTOR. In summary, our data point to a channel-mediated mechanism for the regulation of AMPK through a purinergic signaling pathway. Furthermore, we define AMPK as a pivotal molecule that underlies the regulatory effects of hemichannels on cell survival.