Apoptotic susceptibility of pancreatic alpha cells to environmentally relevant dose levels of bisphenol-A versus dibutyl phthalate is mediated by HSP60/caspase-3 expression in male albino rats

BPA and low-Se exacerbate apoptosis and mitophagy in chicken pancreatic cells by regulating the PTEN/PI3K/AKT/mTOR pathway

INTRODUCTION

Bisphenol A (BPA) is a widespread environmental pollutant which has serious toxic effects on organisms. One of the crucial trace elements is selenium (Se), whose shortage can harm biological tissues and enhance the toxicity of contaminants, in which apoptosis and autophagy are core events.

OBJECTIVES

An in vivo model was established to investigate the effects of BPA and low-Se on chicken pancreatic tissue, and identify the possible potential molecular mechanism.

METHODS

A total of 80 1-day-old broiler chickens (Xinghua Chicken Farm, Harbin, China) were stochastically divided into 4 groups (n = 20/group): Control group, BPA group, low-Se group, and low-Se + BPA group. Pancreatic tissue was collected at day 42 to detect changes in markers.

RESULTS

First, the data showed that BPA and low-Se exposure gave rose to structural abnormalities in pancreatic tissue, oxidative stress, mitochondrial dysfunction and homeostasis imbalance, apoptosis and mitophagy. In addition, the co-exposure of BPA and low-Se caused the most serious damage to pancreatic tissue. In terms of mechanism, it was found that apoptosis and mitophagy induced by BPA and low-Se were related to the activation of PTEN/PI3K/AKT/mTOR pathway.

CONCLUSION

In summary, the study found that BPA and low-Se exacerbated mitochondria damage, apoptosis and mitophagy by regulating the PTEN/PI3K/AKT/mTOR pathway.

Toxicity of Dibutyl phthalate (DBP) toward isolated human blood lymphocytes: Apoptosis initiated from intracellular calcium enhancement and mitochondrial/lysosomal cross talk

Dibutyl phthalate (DBP) is a phthalate ester with wide application in industrial products, so human exposure can happen in workplaces and environment. Conflicting results have been acquired in researches which measured the influences of phthalates contact on immune responses in laboratory animals. Nevertheless, the straight influence of DBP on human lymphocytes and entire mechanisms of its effect against these cells continue to be unexplored. The major purpose of present research was to evaluate the mechanisms which lead to the DBP toxicity on human lymphocytes using accelerated cytotoxicity mechanisms screening (ACMS) technique. Cell viability was determined following12h incubation of lymphocytes with 0.05-1 mM DBP, and mechanistic parameters were assessed after 2, 4 and 6 h of lymphocyte treatment with ½ the IC5012h (0.3 mM), the IC5012h (0.6 mM) and twice the IC5012h (1.2 mM) of DBP. The IC5012 h of a chemical/toxicant is defined as concentration that kills 50 % of cells after 12 h of exposure. The results indicate that DBP exerts toxic effects on isolated human lymphocytes, probably through mitochondrial and lysosomal damage induced by glutathione depletion and oxidative stress. In this study, suppression of cytokines (IL2, INF-gamma and TNF-alpha) production and increase in intracellular calcium were also related to DBP induced lymphocyte toxicity.

The potential Association of Bisphenol A exposure and type 1 diabetes mellitus among Dakahlia Governorate's children sample, Egypt

Background

Bisphenol A (BPA) is an endocrine disrupter affecting glucose homeostasis.

Objectives

This study aimed to investigate BPA's relationship with Type 1 Diabetes Mellitus (T1DM) in Dakahlia Governorate's children, in Egypt.

Subjects materials and methods

The study had two parts: clinical and experimental. Clinical Study was conducted on 200 children, equally divided into control and T1DM groups. They underwent: demographic data, height, weight, body mass index, glycosylated HbA1C, random blood glucose, and urinary BPA measurements. Experimental Study was conducted on 60 adult albino rats. Rats were randomly divided into three equal groups: control group: received 0.5 mL of pure olive oil, group 1: received 20 mg/kg/day BPA, and group 2: received 100 mg/kg/day BPA orally for 6 weeks. Fasting and two hours postprandial glucose levels were measured at the beginning and end of the study. Histopathological examination and imaging study of the pancreas were done.

Results

In clinical study: HbA1C and random blood glucose levels in diabetic children showed a significant increase compared to control. Children in control group showed controlled HbA1C, while the T1DM group showed 86% with poor diabetic control. There was a significant increase in BPA level in the T1DM group compared to the control. Rats that received BPA showed a marked increase in fasting and two hours postprandial glucose levels, histopathological changes in the pancreas with more changes determined in the high dose group, and a significant decrease in the islets of Langerhans diameters with group 2 more affected.

Conclusion

So, BPA exposure could be considered a risk factor for T1DM in children.

Endocrine disruptors in plastics alter β-cell physiology and increase the risk of diabetes mellitus

Plastic pollution breaks a planetary boundary threatening wildlife and humans through its physical and chemical effects. Of the latter, the release of endocrine disrupting chemicals (EDCs) has consequences on the prevalence of human diseases related to the endocrine system. Bisphenols (BPs) and phthalates are two groups of EDCs commonly found in plastics that migrate into the environment and make low-dose human exposure ubiquitous. Here we review epidemiological, animal, and cellular studies linking exposure to BPs and phthalates to altered glucose regulation, with emphasis on the role of pancreatic β-cells. Epidemiological studies indicate that exposure to BPs and phthalates is associated with diabetes mellitus. Studies in animal models indicate that treatment with doses within the range of human exposure decreases insulin sensitivity and glucose tolerance, induces dyslipidemia, and modifies functional β-cell mass and serum levels of insulin, leptin, and adiponectin. These studies reveal that disruption of β-cell physiology by EDCs plays a key role in impairing glucose homeostasis by altering the mechanisms used by β-cells to adapt to metabolic stress such as chronic nutrient excess. Studies at the cellular level demonstrate that BPs and phthalates modify the same biochemical pathways involved in adaptation to chronic excess fuel. These include changes in insulin biosynthesis and secretion, electrical activity, expression of key genes, and mitochondrial function. The data summarized here indicate that BPs and phthalates are important risk factors for diabetes mellitus and support a global effort to decrease plastic pollution and human exposure to EDCs.

Exploring the Effects of Metabolism-Disrupting Chemicals on Pancreatic α-Cell Viability, Gene Expression and Function: A Screening Testing Approach

Humans are constantly exposed to many environmental pollutants, some of which have been largely acknowledged as key factors in the development of metabolic disorders such as diabetes and obesity. These chemicals have been classified as endocrine-disrupting chemicals (EDCs) and, more recently, since they can interfere with metabolic functions, they have been renamed as metabolism-disrupting chemicals (MDCs). MDCs are present in many consumer products, including food packaging, personal care products, plastic bottles and containers, and detergents. The scientific literature has ever-increasingly focused on insulin-releasing pancreatic β-cells as one of the main targets for MDCs. Evidence highlights that these substances may disrupt glucose homeostasis by altering pancreatic β-cell physiology. However, their potential impact on glucagon-secreting pancreatic α-cells remains poorly known despite the essential role that this cellular type plays in controlling glucose metabolism. In the present study, we have selected seven paradigmatic MDCs representing major toxic classes, including bisphenols, phthalates, perfluorinated compounds, metals, and pesticides. By using an in vitro cell-based model, the pancreatic α-cell line αTC1-9, we have explored the effects of these compounds on pancreatic α-cell viability, gene expression, and secretion. We found that cell viability was moderately affected after bisphenol-A (BPA), bisphenol-F (BPF), and perfluorooctanesulfonic acid (PFOS) exposure, although cytotoxicity was relatively low. In addition, all bisphenols, as well as di(2-ethylhexyl) phthalate (DEHP) and cadmium chloride (CdCl₂), promoted a marked decreased on glucagon secretion, together with changes in the expression of glucagon and/or transcription factors involved in cell function and identity, such as Foxo1 and Arx. Overall, our results indicated that most of the selected chemicals studied caused functional alterations in pancreatic α-cells. Moreover, we revealed, for the first time, their direct effects on key molecular aspects of pancreatic α-cell biology.

Screening of Metabolism-Disrupting Chemicals on Pancreatic α-Cells Using In Vitro Methods

Metabolism-disrupting chemicals (MDCs) are endocrine disruptors with obesogenic and/or diabetogenic action. There is mounting evidence linking exposure to MDCs to increased susceptibility to diabetes. Despite the important role of glucagon in glucose homeostasis, there is little information on the effects of MDCs on α-cells. Furthermore, there are no methods to identify and test MDCs with the potential to alter α-cell viability and function. Here, we used the mouse α-cell line αTC1-9 to evaluate the effects of MDCs on cell viability and glucagon secretion. We tested six chemicals at concentrations within human exposure (from 0.1 pM to 1 µM): bisphenol-A (BPA), tributyltin (TBT), perfluorooctanoic acid (PFOA), triphenylphosphate (TPP), triclosan (TCS), and dichlorodiphenyldichloroethylene (DDE). Using two different approaches, MTT assay and DNA-binding dyes, we observed that BPA and TBT decreased α-cell viability via a mechanism that depends on the activation of estrogen receptors and PPARγ, respectively. These two chemicals induced ROS production, but barely altered the expression of endoplasmic reticulum (ER) stress markers. Although PFOA, TPP, TCS, and DDE did not alter cell viability nor induced ROS generation or ER stress, all four compounds negatively affected glucagon secretion. Our findings suggest that αTC1-9 cells seem to be an appropriate model to test chemicals with metabolism-disrupting activity and that the improvement of the test methods proposed herein could be incorporated into protocols for the screening of diabetogenic MDCs.

Chemical Compounds and Ambient Factors Affecting Pancreatic Alpha-Cells Mass and Function: What Evidence?

The exposure to different substances present in the environment can affect the ability of the human body to maintain glucose homeostasis. Some review studies summarized the current evidence about the relationships between environment and insulin resistance or beta-cell dysfunction. Instead, no reviews focused on the relationships between the environment and the alpha cell, although in recent years clear indications have emerged for the pivotal role of the alpha cell in glucose regulation. Thus, the aim of this review was to analyze the studies about the effects of chemical, biological, and physical environmental factors on the alpha cell. Notably, we found studies focusing on the effects of different categories of compounds, including air pollutants, compounds of known toxicity present in common objects, pharmacological agents, and compounds possibly present in food, plus studies on the effects of physical factors (mainly heat exposure). However, the overall number of relevant studies was limited, especially when compared to studies related to the environment and insulin sensitivity or beta-cell function. In our opinion, this was likely due to the underestimation of the alpha-cell role in glucose homeostasis, but since such a role has recently emerged with increasing strength, we expect several new studies about the environment and alpha-cell in the near future.