Polymorphisms in the TNF-α and IL10 gene promoters and risk of arsenic-induced skin lesions and other nondermatological health effects

The probable reasons of arsenic susceptibility in a chronically exposed population of West Bengal

Arsenic is potent human carcinogen which affects millions of people across the globe. Arsenic induced pre-cancerous and cancerous skin lesions are hall marks of chronic arsenic toxicity. Even then, only 15%-20% of the population manifest arsenic-induced skin lesions but the rest do not, the reason for which in not very clear. Not only that, conjunctival irritations of the eyes, peripheral neuropathy and respiratory distress are the non-dermatological health effects which are often manifested in them in addition to the cancers of skin and other internal organs. In this work we have considered 233 arsenic exposed individuals with skin lesions and 205 arsenic exposed individuals without skin lesions from the highly arsenic affected Murshidabad district of West Bengal. We have compared arsenic exposure in the two groups through drinking water. Both the study groups have similar levels of arsenic exposure, drinking same arsenic laden water. Results show that higher amounts of arsenic were retained in the nails and hair of the skin lesion group compared to the no skin lesion group. Significant higher amounts of chromosomal aberration and micronucleus formation were found in the skin lesion group, than the no skin lesion group. Incidences of conjunctival irritations of the eyes, peripheral neuropathy and respiratory distress were much higher in the former group compared to the later. We, thus found that one group was more susceptible than the other, even with similar levels of arsenic exposure. We have tried to identify and discuss the probable reasons for this observation with reference to our previous works in the exposed population from West Bengal, India.

Association between urinary arsenic concentration and genetic polymorphisms in Korean adults

Arsenic (As) is a human carcinogen widely distributed in the environment. This study evaluated the association between the urinary As concentration and single nucleotide polymorphisms (SNPs) in Korean adults to determine the genetic factors related to As concentration. The study included 496 participants for the genome-wide association study (GWAS) and 1483 participants for the candidate gene approach study. Participants were 19 years and older. The concentrations of total As (Tot As) and total As metabolites (Tmet As, the sum of inorganic As and their metabolites; arsenite, arsenate, monomethylarsonic, and dimethylarsinic acid) in the urine were analyzed. The GWAS identified four SNPs (rs1432523, rs3776006, rs11171747, and rs807573) associated with urinary Tot As and four SNPs (rs117605537, rs3776006, rs11171747, and rs148103384) significantly associated with urinary Tmet As concentration (P < 1 × 10-4). The candidate gene study identified two SNPs (PRDX2 rs10427027 and GLRX rs3822751) in genes related to the reduction reaction associated with urinary Tot As and Tmet As. This study suggests that genetic factors may play a role in regulating As metabolism in the human body, affecting both exposure levels and its potential health risks in the general Korean population, even at low exposure levels.

Supplementary Information

The online version contains supplementary material available at 10.1007/s43188-023-00216-x.

Prediction of Hazardous Effect of Heavy Metals of Point-Source Wastewater on Fish (Anabas cobojius) and Human Health

Aquatic ecosystems are exceedingly contrived due to industrial dispenses, as a huge amount of toxicants especially heavy metals are released, causing drastic effects on aquatic lives and the human body. This study was performed to assess the quality of point-source industrial wastewater at varying percentage levels and their subsequent hazardous effect on fish (Anabas cobojius) and human health. The perceived value revealed that water quality parameters declined with the increase of wastewater concentration and trace metal evaluation index (TEI) ascertained a high level of water pollution due to Cr, Mn, Fe, Co, Ni, Cu, Zn, and As content for all percentages of wastewater. Concentration of wastewater and culture treatment duration largely impacted on fish mortality rate, body dis-pigmentation, mucus secretion rate, coagulation of mucus all over the body, and accumulation of heavy metals by fish samples. Metal pollution index (MPI) indicated low contamination of fish by the measured elements. Zn and Hg exceeded the threshold limit of target hazard quotient (THQ > 1) and contributed significantly to non-carcinogenic health implications for both the population group. Maximum hazard index in adults and children was observed to be 10.638 and 16.548 for 100% effluent at 96-h exposure period and the overall HI value manifested a very high to medium significant health effects regardless of age. Carcinogen Pb showed insignificant risk but Cr and Ni showed extremely high to medium-high risk for both the population group, and children were found more vulnerable receptors than adults. However, source of heavy metals in wastewater and fish samples stipulated anthropogenic sources.

Development on potential skin anti-aging agents of Cosmos caudatus Kunth via inhibition of collagenase, MMP-1 and MMP-3 activities

BACKGROUND

Skin aging is associated with degradation of collagen by matrix metalloproteinases (MMPs), which leads to loss of skin elasticity and formation of wrinkles. Cosmos caudatus Kunth (CC) has been traditionally claimed as an anti-aging agent in Malaysia. Despite its well-known antioxidant activity, the anti-aging properties of CC was not validated.

PURPOSE

This study aimed to investigate the anti-aging potential of CC extracts and fractions, particularly their inhibition of collagenase, MMP-1 and MMP-3 activities in human dermal fibroblasts CCD-966SK, followed by isolation, identification and analysis of their bioactive constituents.

STUDY DESIGN AND METHODS

DPPH assay was firstly used to evaluate the antioxidant activity throughout the bioactivity-guided fractionation. Cell viability was determined using MTS assay. Collagenase activity was examined, while MMP-1 and MMP-3 expression were measured using qRT-PCR and western blotting. Then, chemical identification of pure compounds isolated from CC fractions was done by using ESIMS, ¹H and ¹³C NMR spectroscopies. HPLC analyses were carried out for bioactive fractions to quantify the major components.

RESULTS

Throughout the antioxidant activity-guided fractionation, fractions CC-E2 and CC-E3 with antioxidant activity and no toxicity towards CCD-966SK cells were obtained from CC 75% ethanol partitioned layer (CC-E). Both fractions inhibited collagenase activity, MMP-1 and MMP-3 mRNA and protein expression, as well as NF-κB activation induced by TNF-α in CCD-966SK cells. 14 compounds, which mainly consists of flavonoids and their glycosides, were isolated. Quercitrin (14.79% w/w) and quercetin (11.20% w/w) were major compounds in CC-E2 and CC-E3, respectively, as quantified by HPLC. Interestingly, both fractions also inhibited the MMP-3 protein expression synergistically, compared with treatment alone.

CONCLUSION

The quantified CC fractions rich in flavonoid glycosides exhibited skin anti-aging effects via the inhibition of collagenase, MMP-1 and MMP-3 activities, probably through NF-κB pathway. This is the first study reported on MMP-1 and MMP-3 inhibitory activity of CC with its chemical profile, which revealed its potential to be developed as anti-aging products in the future.

Arsenic in the foodstuffs: potential health appraisals in a developing country, Bangladesh

The presence of highly poisonous arsenic (As) elements in food concerns humans and animals. In Bangladesh, arsenic-contaminated groundwater is frequently utilized for agricultural irrigation. This is a significant source of arsenic pollution in the human food chain. For the first time, we investigated the presence of total arsenic in various foodstuffs obtained from 30 distinct agricultural eco-zones of Bangladesh to understand human exposure to arsenic through the food chain in Bangladesh. The greatest and lowest As concentrations were reported in fish among the examined dietary items (0.55 mg/kg, fw) and fruit (0.0068 mg/kg, fw), respectively. The results show that arsenic consumption from daily diet and food with drinking water was estimated to be 0.0352 mg/day for rural residents and 0.2002 mg/day for urban residents, respectively. The highest target hazard quotients (THQ) of arsenic in the fish samples surpassed the allowable limit (> 1), proving that fish are the primary dietary items influencing the possible danger to health. However, the target cancer risk (TR) from nutritional arsenic consumption was likewise higher than tolerable. A value of 10^-4 indicates that Bangladeshi people are continuously exposed to arsenic, which has carcinogenic and non-carcinogenic dangers. Overall, our results highlight that people in Bangladesh are exposed to hazardous levels of arsenic throughout the food chain, which should be addressed to ensure the country's food safety.

Arsenic Activates the NLRP3 Inflammasome and Disturbs the Th1/Th2/Th17/Treg Balance in the Hippocampus in Mice

Arsenic exerts neurotoxicity and immunomodulatory effects. Studies have shown that the nervous system is not considered to be an immune-privileged site. However, the effect of arsenic-induced neuroimmune toxicity has rarely been reported. We aimed to investigate the toxic effects of arsenic on the NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome and the Th1/Th2/Th17/Treg balance in the brain tissue of mice. Mice were exposed to NaAsO₂ (0, 2.5, 5, and 10 mg/kg) for 24 h. Our results showed that 10 mg/kg arsenic exposure significantly decreased brain and hippocampal indices (p < 0.05). The mRNA and protein levels of the blood‒brain barrier (BBB) tight junction protein occludin were decreased in the 5 and 10 mg/kg arsenic-treated groups. Compared with those in the control group, NLRP3 protein levels in 10 mg/kg arsenic-treated mice, caspase-1 protein levels in 2.5, 5, and 10 mg/kg arsenic-treated mice, and IL-1β protein levels in 5 and 10 mg/kg arsenic-treated mice were increased in the hippocampus (p < 0.05). In addition, arsenic induced a hippocampal inflammatory response by upregulating the mRNA levels of the proinflammatory factors IL-6 and TNF-α and downregulating the mRNA level of the anti-inflammatory factor IL-10. Moreover, arsenic decreased the mRNA levels of the Th1 and Th2 transcription factors T-bet and GATA3 and the cytokines IFN-γ and IL-4 and increased the mRNA levels of the Th17 transcription factor RORγt and the cytokine IL-22 (p < 0.05). Collectively, our study demonstrated that arsenic could induce immune-inflammatory responses by regulating the NLRP3 inflammasome and CD4⁺ T lymphocyte differentiation. These results provide a novel strategy to block the arsenic-induced impairment of neuroimmune responses.

Human health impact due to arsenic contaminated rice and vegetables consumption in naturally arsenic endemic regions

Rice and vegetables cultivated in naturally arsenic (As) endemic areas are the substantial source of As body loading for persons using safe drinking water. However, tracing As intake, particularly from rice and vegetables by biomarker analysis, has been poorly addressed. This field investigation was conducted to trace the As transfer pathway and measure health risk associated with consuming As enriched rice and vegetables. Purposively selected 100 farmers from five sub-districts of Chandpur, Bangladesh fulfilling specific requirements constituted the subjects of this study. A total of 100 Irrigation water, soils, rice, and vegetable samples were collected from those farmers' who donated scalp hair. Socio-demographic and food consumption data were collected face to face through questionnaire administration. The mean As level in irrigation water, soils, rice, vegetables, and scalp hairs exceeded the acceptable limit, while As content was significant at 0.1%, 5%, 0.1%, 1%, and 0.1% probability levels, respectively, in all five locations. Arsenic in scalp hair is significantly (p ≤ 0.01) correlated with that in rice and vegetables. The bioconcentration factor (BCF) for rice and vegetables is less than one and significant at a 1% probability level. The average daily intake (ADI) is higher than the RfD limit for As. Both grains and vegetables have an HQ (hazard quotient) > 1. Maximum incremental lifetime cancer risk (ILCR) showed 2.8 per 100 people and 1.6 per 1000 people are at considerable and threshold risk, respectively. However, proteinaceous and nutritious food consumption might have kept the participants asymptomatic. The PCA analysis showed that the first principle component (PC1) explains 91.1% of the total variance dominated by As in irrigation water, grain, and vegetables. The dendrogram shows greater variations in similarity in rice and vegetables As, while the latter has been found to contribute more to human body loading compared to grain As.

Cyclic Gate Recurrent Neural Networks for Time Series Data with Missing Values

Gated Recurrent Neural Networks (RNNs) such as LSTM and GRU have been highly effective in handling sequential time series data in recent years. Although Gated RNNs have an inherent ability to learn complex temporal dynamics, there is potential for further enhancement by enabling these deep learning networks to directly use time information to recognise time-dependent patterns in data and identify important segments of time. Synonymous with time series data in real-world applications are missing values, which often reduce a model’s ability to perform predictive tasks. Historically, missing values have been handled by simple or complex imputation techniques as well as machine learning models, which manage the missing values in the prediction layers. However, these methods do not attempt to identify the significance of data segments and therefore are susceptible to poor imputation values or model degradation from high missing value rates. This paper develops Cyclic Gate enhanced recurrent neural networks with learnt waveform parameters to automatically identify important data segments within a time series and neglect unimportant segments. By using the proposed networks, the negative impact of missing data on model performance is mitigated through the addition of customised cyclic opening and closing gate operations. Cyclic Gate Recurrent Neural Networks are tested on several sequential time series datasets for classification performance. For long sequence datasets with high rates of missing values, Cyclic Gate enhanced RNN models achieve higher performance metrics than standard gated recurrent neural network models, conventional non-neural network machine learning algorithms and current state of the art RNN cell variants.

Interaction between Single Nucleotide Polymorphisms (SNP) of Tumor Necrosis Factor-Alpha (TNF-α) Gene and Plasma Arsenic and the Effect on Estimated Glomerular Filtration Rate (eGFR)

When poisons enter the human body, tumor necrosis factor (TNF-α) will increase and cause damage to tissues through oxidative stress or inflammatory reaction. In previous studies, arsenic (As) has known to cause many health problems. Some studies have shown that As exposure is negatively correlated with estimated glomerular filtration rate (eGFR), or with the prevalence of proteinuria. At present, there are few studies focusing on the effects of As exposure and TNF-α single nucleotide polymorphism (SNP) to eGFR; thus, this study was intended to explore the interactions between TNF-α SNPs and plasma As and their effects on eGFR. A cohort of 500 adults, aged 30 to 70 years, was randomly selected from Taiwan Biobank (TWB). We used the gene chip to screen out seven SNPs of the TNF-α gene and used the results, combined with questionnaires, biochemical tests, and stored plasma samples from the TWB, for the analysis of As by inductively coupled plasma mass spectrometry (ICP-MS). After adjustments for BMI, hypertension, hyperlipidemia, kidney stones, and smoking habits, multiple regression statistics were performed to explore the interaction between SNPs and plasma As with eGFR. In this sample of the general population, plasma As had a significant association with the decline of eGFR (β (SE) = −7.92 (1.70), p < 0.0001). TNF-α gene SNP rs1800629 had the property of regulating TNF-α, which interacts with plasma As; individuals with the AG type had a significantly lower eGFR than those with the GG type, by 9.59 mL/min/1.73 m2 (p < 0.05), which, regarding the dominant model, could infer that the A allele is a risk allele. SNP rs769177 had no interaction with plasma As; however, participants with the TT or TC type had significantly higher eGFR levels than the CC carriers, by 4.02 mL/min/1.73 m2 (p < 0.05). While rs769176 interacted with plasma As, if a person with the TC type had a higher plasma As concentration, that would sustain higher eGFR. This study found that certain SNPs of the TNF-α gene would be robust to the decline of eGFR caused by As exposure. Still, we need further research to confirm the protective regulation mechanism of these SNPs.

Genetic Diversity of Human Host Genes Involved in Immune Response and the Binding of Malaria Parasite in Patients Residing along the Thai-Myanmar border

Polymorphisms of the genes encoding proteins involved in immune functions and the binding of malaria parasites to human host cells have been the focus of research in recent years, aiming to understand malaria pathogenesis and case severity and to exploit this knowledge to assert control over malaria. This study investigated the genetic diversity of the human host genes encoding proteins that are involved in immune functions and malaria parasite binding, i.e., MCP1 (−2518), TGFβ1 (−509), TNFα (−308), IL4 (VNTR), IL6 (−174), IL10 (−3575), TLR4 (299), CD36 (−188), and ICAM1 (469) in patients with mono-infection of Plasmodium falciparum and Plasmodium vivax infections in the multidrug-resistant areas along the Thai-Myanmar border. The association between gene polymorphisms and parasite density was also investigated. Genomic DNA (gDNA) of P. falciparum and P. vivax were extracted from whole blood and dried blood spot (DBS). Gene amplification and genotyping were performed by PCR and PCR-RFLP analysis, respectively. Of these samples, 178 and 209 samples were, respectively, mono-infection with P. falciparum and P. vivax. The ratio of P. falciparum: P. vivax was 46%:54%. Results showed marked variation in the frequency distribution and patterns of the genotypes and gene alleles of the nine immune response genes or human host genes. The SNPs of TGFβ1, IL10 and ICAM1, were significantly associated with P. falciparum, but not P. vivax parasite density. TGFβ1, IL10 and ICAM1, may play more significant roles in modulating P. falciparum than P. vivax parasitemia. The prevalence of the genotypes and gene alleles of these genes, including their association with parasite density, may vary depending on patient ethnicity and endemic areas. Information obtained from each endemic area is essential for treatment strategies and the development of vaccines for malaria prophylaxis in specific areas.

MicroRNAs play an important role in contributing to arsenic susceptibility in the chronically exposed individuals of West Bengal, India

Arsenic exposure by groundwater contamination is a menace which threatens more than 26 million individuals of West Bengal. Interestingly, with similar levels of arsenic exposure, only 15-20% of the population show arsenic-induced skin lesions, the hallmarks of chronic arsenic toxicity, but the rest do not. In this study, our aim was to identify whether microRNAs (miRNA) have any role to play in causing such arsenic susceptibility. Global plasma miRNA profiling was done in 12 arsenic-exposed individuals with skin lesions and 12 exposed individuals without skin lesions. Two hundred two miRNAs were found to be differentially regulated between the two study groups. Results were validated by quantitative real-time PCR in 30 exposed subjects from each of the groups, which showed that among others miR-21, miR-23a, miR-27a, miR-122, miR-124, miR-126, miR-619, and miR-3613 were significantly upregulated and miR-1282 and miR-4530 were downregulated in the skin lesion group compared with the no skin lesion group. Bioinformatic analyses predicted that these altered miRNAs have targets in 7 different biochemical pathways, including glycerophospholipid metabolism, colorectal cancer, glycosphingolipid biosynthesis, T cell receptor signaling, and neurotrophin signaling pathways; glycerophospholipid metabolism pathway being the most enriched pathway. Association study show that these microRNAs contribute significantly to the increased prevalence of other non-dermatological health effects like conjunctival irritations of the eyes and respiratory distress in the study subjects. To our knowledge, this is the first study of its kind involving miRNA expressions contributing to arsenic susceptibility in the exposed population of West Bengal.

Health effects inflicted by chronic low-level arsenic contamination in groundwater: A global public health challenge

Groundwater arsenic (As) contamination is a global public health concern. The high level of As exposure (100-1000 μg/L or even higher) through groundwater has been frequently associated with serious public health hazards, e.g., skin disorders, cardiovascular diseases, respiratory problems, complications of gastrointestinal tract, liver and splenic ailments, kidney and bladder disorders, reproductive failure, neurotoxicity and cancer. However, reviews on low-level As exposure and the imperative health effects are far less documented. The World Health Organization (WHO) and the United States Environmental Protection Agency (USEPA) has set the permissible standard of As in drinking water at 10 μg/L. Considering the WHO and USEPA guidelines, most of the developed countries have established standards at or below this guideline. Worldwide many countries including India have millions of aquifers with low-level As contamination (≤50 μg/L). The exposed population of these areas might not show any As-related skin lesions (hallmark of As toxicity particularly in a population consuming As contaminated groundwater >300 μg/L) but might be subclinically affected. This review has attempted to encompass the wide range of health effects associated with chronic low-level As exposure ≤50 μg/L and the probable mechanisms that might provide a better insight regarding the underlying cause of these clinical manifestations. Therefore, there is an urgent need to create mass awareness about the health effects of chronic low-level As exposure and planning of proper mitigation strategies.

Effect of arsenic exposure on early eye development in zebrafish (Danio rerio)

Arsenic is a metalloid that contaminates drinking water supplies worldwide. Owing to concerns for human health, the World Health Organization and the US Environmental Protection Agency have established a safe level in drinking water of ≤10 ppb. Recently, arsenic exposure has also been linked to lower IQ values in children. The effect of arsenic on neurogenesis, specifically eye development, has not been widely explored. This study aimed to examine the effect of environmentally relevant concentrations of arsenic on early eye development by morphological and molecular analysis. The zebrafish, Danio rerio, was chosen to model the impact of arsenic on retinogenesis because of similarities to human eye development. Arsenic exposure to zebrafish embryos resulted in a significant increase in eye diameter at 14 days postfertilization. This was coupled with a trend in thinning of the retinal pigmented epithelium (RPE) layer in embryos exposed to 500 ppb arsenic. Reverse transcription-quantitative polymerase chain reaction analysis of genes associated with eye development revealed differential expression of Pax6a, Pax2a, Ngn1, Sox2 and Shha relative to control. Pax6a, Pax2a and Sox2 are important in the formation of the RPE. Proper formation of the RPE is necessary for growth of the sclera, which, in turn, is responsible for maintaining the shape of the eye. This could potentially be explained by the disruption of gene expression under arsenic exposure during critical time points in early eye development. These results provide insight into the effects arsenic may be having on early eye development in children exposed to contaminated drinking water supplies.

Individual susceptibility to arsenic-induced diseases: the role of host genetics, nutritional status, and the gut microbiome

Arsenic (As) contamination in water or food is a global issue affecting hundreds of millions of people. Although As is classified as a group 1 carcinogen and is associated with multiple diseases, the individual susceptibility to As-related diseases is highly variable, such that a proportion of people exposed to As have higher risks of developing related disorders. Many factors have been found to be associated with As susceptibility. One of the main sources of the variability found in As susceptibility is the variation in the host genome, namely, polymorphisms of many genes involved in As transportation, biotransformation, oxidative stress response, and DNA repair affect the susceptibility of an individual to As toxicity and then influence the disease outcomes. In addition, lifestyles and many nutritional factors, such as folate, vitamin C, and fruit, have been found to be associated with individual susceptibility to As-related diseases. Recently, the interactions between As exposure and the gut microbiome have been of particular concern. As exposure has been shown to perturb gut microbiome composition, and the gut microbiota has been shown to also influence As metabolism, which raises the question of whether the highly diverse gut microbiota contributes to As susceptibility. Here, we review the literature and summarize the factors, such as host genetics and nutritional status, that influence As susceptibility, and we also present potential mechanisms of how the gut microbiome may influence As metabolism and its toxic effects on the host to induce variations in As susceptibility. Challenges and future directions are also discussed to emphasize the importance of characterizing the specific role of these factors in interindividual susceptibility to As-related diseases.

A Systems Toxicology-based Approach Reveals Biological Pathways Dysregulated by Prenatal Arsenic Exposure

BACKGROUND

Prenatal exposure to inorganic arsenic (iAs) is associated with dysregulated fetal gene and protein expression. Potential biological mechanisms that underlie these changes include, but are not limited to, changes to the epigenome.

OBJECTIVE

The aim of the present study was to identify whether the expression of key genes, proteins, or both and their associated biological pathways are perturbed by compiling datasets from studies on prenatal arsenic exposure.

METHODS

We compiled datasets from 12 studies that analyzed the relationship between prenatal iAs exposure and changes to the fetal epigenome (5-methyl cytosine), transcriptome (mRNA expression), and/or proteome (protein expression).

FINDINGS

Across the 12 studies, a set of 845 unique genes was identified and found to enrich for their role in biological pathways, including the peroxisome proliferator-activated receptor, nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, and the glucocorticoid receptor. Tumor necrosis factor was identified as a putative cellular regulator underlying most (n = 277) of the identified iAs-associated gene or protein expression changes.

CONCLUSIONS

The identification of the common set of genes across numerous human cohorts suggests a conserved biological response to prenatal arsenic exposure. The genes/proteins and their associated pathways may be useful in future mechanistic investigations of iAs associated diseases.

Seasonal variation of heavy metals in water and sediments in the Halda River, Chittagong, Bangladesh

The present study was carried out to assess the contamination levels of heavy metals (Pb, Cd, Cr, Cu, Hg, Al, Ni, Co, Zn, Mn) in surface water and sediment of the Halda River. The observed order of heavy metal concentration in water for Al > Ni > Zn > Mn > Cu > Cd > Pb > Cr > Co > Hg (mg/l) and for sediments Al > Mn > Zn > Ni > Cr > Pb > Cu > Co > Cd > Hg (mg/kg), respectively. The concentrations of Pb, Cd, Cr, Cu, Hg, Al, Ni, Co, Zn, and Mn in water, whereas in sediment Pb, Cu, Al, Ni, Co, Zn, and Mn were found above the permissible limit (WHO 2004; USEPA 2006; EPA 1986, 2002 and ECR 1997). Significant variations in the concentrations of Al and Ni were found in water (p < 0.05) while Cr, Cu, Pb, Co, Mn, and Ni showed substantial changes in sediment (p < 0.05). Principal component analysis (PCA) and correlation matrix revealed anthropogenic intrusions of Pb, Cd, Cr, Cu, Hg, Al, Ni, Co, Zn, and Mn in water and sediment. In case of water, very strong linear relationship was found in Hg vs Pb (0.941), Mn vs Zn (0.939), and Ni vs Cu (0.922) at the significance level 0.01. In sediment, very strong linear relationships were found in Mn vs Cr (0.999), Co vs Ni (0.999), Ni vs Cu (0.994), Zn vs Pb (0.993), Co vs Cu (0.992), Cu vs Cr (0.990), Mn vs Cu (0.989), Mn vs Ni (0.975), Mn vs Co (0.975), Ni vs Cr (0.974), Co vs Cr (0.972), Mn vs Pb (0.951), Cr vs Pb (0.948), Zn vs Cr (0.944), and Mn vs Zn (0.941) at the significance level 0.01 which direct that their common origin entirely from industrial effluents, municipal wastes, and agricultural activities. The study shows that seasonal water flows/water discharge (pre-monsoon, monsoon, and post-monsoon) have an impact on the mobility of metals. Elevated levels of metals were detected during monsoon in sediments (Pb, Cr, Cu, Al, Ni, Co, Zn, Mn) and post-monsoon in water (Cd, Hg, Ni, Co, Mn). The detection of high-risk metals in the Halda River may demonstrate that metals can cause significant effects on fry and fingerlings of the Gangetic carp fishery and prawn fishery (via sub-lethal and lethal effects and bioaccumulation or secondary poisoning of metals to fish and prawn).

Increased microRNA 21 expression contributes to arsenic induced skin lesions, skin cancers and respiratory distress in chronically exposed individuals

More than 26 million people in West Bengal, India, are exposed to arsenic through drinking water, leading to several deleterious endpoints including precancerous and cancerous skin lesions and other non-dermatological health effects. Here, our aim was to identify whether miR21 is associated with such dermatological and non-dermatological health outcomes in chronically exposed humans. A total of 123 subjects from West Bengal were recruited for this study (45 exposed individuals with skin lesions, 38 exposed individuals without skin lesions and 40 unexposed individuals). The miR21 expression patterns in the lymphocytes were studied by quantitative realtime PCR and the effects on downstream targets were validated by Western blotting. Associations between the miR21 expression patterns and non-dermatological health effects were determined from epidemiological survey data. In vitro studies were done with low dose (0.05ppm) of chronic arsenic exposure to HaCaT cells for 15 passages. Interestingly, within the exposed group, the skin lesion individuals showed almost 4.5 fold up-regulation of miR21 compared to the no skin lesion group. The expression of the downstream targets of miR21 (PTEN and PDCD4) varied inversely, while the expression of pAKT and PI3K varied proportionately with its expression levels. Results of in vitro studies showed similar trends. Again miR21 was 2.03 fold up-regulated in the exposed individuals with respiratory diseases compared to the individuals without the same. This study for the first time shows that miR21 plays an important role in contributing to arsenic induced dermatological and non-dermatological health outcomes in an exposed population.

Genetic susceptibility to arsenic-induced skin lesions and health effects: a review

Arsenic toxicity in humans manifests several outcomes in humans, which include arsenic-induced genomic instability, DNA damage, impaired DNA repair, carcinogenesis, dermatological lesions and other health related problems. Of the 137 million individuals affected, nearly 26 million individuals are in the state of West Bengal, India. Studies have identified dermatological lesions like keratosis, basal cell carcinoma, Bowen’s diseases, squamous cell carcinoma, etc., as key indicators of aggressive arsenic toxicity in humans. Although a large number of individuals are exposed to arsenic but only about 15 to 20 % individuals showed arsenic induced skin lesions. This clearly indicates that genetic susceptibility plays an important role in arsenic susceptibility. Analyses of genetic susceptibility have been carried out to study the prevalence of single nucleotide polymorphisms (SNPs) in number of genes as they might be involved arsenic metabolism and detoxification. It has been observed that a number SNPs in these genes were significantly associated with arsenic induced skin lesions and other health effects. In the present review we try to coalesce the different observations and associations of SNPs with arsenic-induced toxicity, with special emphasis on the study population from West Bengal. We have adopted certain candidate gene approaches to evaluate the association of arsenic-induced toxic outcomes like skin lesions, conjunctival irritations, DNA damage, epimutagenesis, cancer, etc. This review shall be helpful in understanding the importance of genetic make-up of an individual towards evaluating the xenotoxic outcomes, like those in case of arsenic exposure.

Protective effect of Emblica-officinalis in arsenic induced biochemical alteration and inflammation in mice

Exposure to arsenic in individuals has been found to be associated with immune related problems. In earlier studies, we have demonstrated that amla protects against arsenic induced oxidative stress and apoptosis in thymus and spleen of mice. In continuation to that the present study has therefore been focused to investigate the protective efficacy of amla in arsenic induced inflammation and immunotoxicity in mice. The results showed that arsenic treatment significantly increased serum urea levels (69 %), glucose levels (48 %) and triglyceride levels (66 %) as compared to controls. Mice exposed to arsenic exhibited significant increased in TNF-α (4.3-fold), serum Interleukin-1 beta (threefold), Interleukin-6 (3.8-fold) as compared to controls. Arsenic exposure increased the relative frequency of CD8+ (Tc) cells sub-population (18.9 %) and decreased CD4+ (Th) cells (2.6 %). Arsenic exposure also significantly decreased T (CD3) and B (CD19) cells (21.1 %) as compared to controls. Simultaneously treatment with arsenic and amla significantly inhibited serum urea levels (47 %), glucose levels (50 %) and triglyceride levels (14 %). It also significantly decreased the TNF-α (1.1-fold), levels of IL-1β (1.6-fold), levels of Interleukin-6 (1.3-fold) in serum as compared to those treated with arsenic alone. Simultaneously treatment with arsenic and amla restored the alterations in CD8+ and CD4+ cells and also recovered the damages in B and T sub cells population. Results of the present study clearly indicate that arsenic induced immunotoxicity linked with inflammation has been significantly protected through simultaneous treatment with arsenic and amla that was due to anti-inflammatory and antioxidant activity of amla.

Integrated phytobial remediation for sustainable management of arsenic in soil and water

Arsenic (As), cited as the most hazardous substance by the U.S. Agency for Toxic Substance and Disease Registry (ATSDR, 2005), is an ubiquitous metalloid which when ingested for prolonged periods cause extensive health effects leading to ultimate untimely death. Plants and microbes can help mitigate soil and groundwater As problem since they have evolved elaborate detoxification machineries against this toxic metalloid as a result of their coexistence with this since the origin of life on earth. Utilization of the phytoremediation and bioremediation potential of the plants and microbes, respectively, is now regarded as two innovative tools that encompass biology, geology, biotechnology and allied sciences with cutting edge applications for sustainable mitigation of As epidemic. Discovery of As hyperaccumulating plants that uptake and concentrate large amounts of this toxic metalloid in their shoots or roots offered new hope to As phytoremediation, solar power based nature's own green remediation. This review focuses on how phytoremediation and bioremediation can be merged together to form an integrated phytobial remediation which could synergistically achieve the goal of large scale removal of As from soil, sediment and groundwater and overcome the drawbacks of the either processes alone. The review also points to the feasibility of the introduction of transgenic plants and microbes that bring new hope for more efficient treatment of As. The review identifies one critical research gap on the importance of remediation of As contaminated groundwater not only for drinking purpose but also for irrigation purpose and stresses that more research should be conducted on the use of constructed wetland, one of the most suitable areas of application of phytobial remediation. Finally the review has narrowed down on different phytoinvestigation and phytodisposal methods, which constitute the most essential and the most difficult part of pilot scale and field scale applications of phytoremediation programs.

Prenatal exposure to arsenic and cadmium impacts infectious disease-related genes within the glucocorticoid receptor signal transduction pathway

There is increasing evidence that environmental agents mediate susceptibility to infectious disease. Studies support the impact of prenatal/early life exposure to the environmental metals inorganic arsenic (iAs) and cadmium (Cd) on increased risk for susceptibility to infection. The specific biological mechanisms that underlie such exposure-mediated effects remain understudied. This research aimed to identify key genes/signal transduction pathways that associate prenatal exposure to these toxic metals with changes in infectious disease susceptibility using a Comparative Genomic Enrichment Method (CGEM). Using CGEM an infectious disease gene (IDG) database was developed comprising 1085 genes with known roles in viral, bacterial, and parasitic disease pathways. Subsequently, datasets collected from human pregnancy cohorts exposed to iAs or Cd were examined in relationship to the IDGs, specifically focusing on data representing epigenetic modifications (5-methyl cytosine), genomic perturbations (mRNA expression), and proteomic shifts (protein expression). A set of 82 infection and exposure-related genes was identified and found to be enriched for their role in the glucocorticoid receptor signal transduction pathway. Given their common identification across numerous human cohorts and their known toxicological role in disease, the identified genes within the glucocorticoid signal transduction pathway may underlie altered infectious disease susceptibility associated with prenatal exposures to the toxic metals iAs and Cd in humans.

Arsenic and lead in foods: a potential threat to human health in Bangladesh

The non-carcinogenic and carcinogenic risk of arsenic and lead to adults and children via daily dietary intake of food composites in Bangladesh was estimated. The target hazard quotients (THQs), hazard index (HI) and target carcinogenic risk (TR) were calculated to evaluate the non-carcinogenic and carcinogenic health risk from arsenic and lead. Most of the individual food composites contain a considerable amount of arsenic and lead. The highest mean concentrations of arsenic were found in cereals (0.254 mg kg⁻¹ fw) and vegetables (0.250 mg kg⁻¹ fw), and lead in vegetables (0.714 mg kg⁻¹ fw) and fish (0.326 mg kg⁻¹ fw). The results showed the highest THQs of arsenic in cereals and lead in vegetables for both adults and children which exceeded the safe limit (> 1) indicating that cereals and vegetables are the main food items contributing to the potential health risk. The estimated TR from ingesting dietary arsenic and lead from most of the foods exceeded 10⁻⁶, indicating carcinogenic risks for all adult people of the study area.

Arsenic induced overexpression of inflammatory cytokines based on the human urothelial cell model in vitro and urinary secretion of individuals chronically exposed to arsenic

Chronic persistent inflammation could play an important role in the pathogenesis of some malignancies, and inflammation is a critical factor for bladder cancer development. In this study, we measured urine levels of transforming growth factor-α (TGF-α), tumor necrosis factor-α (TNF-α), and IL-8 in arsenic exposure workers and expressions of inflammatory cytokines in human urothelial cells in vivo and in vitro. We found the concentrations of IL-8, TNF-α, and TGF-α presented in urine were significantly elevated in the high urinary arsenic workers compared with the low urinary arsenic workers. Multiple regression analysis showed that the urinary IL-8 level was significantly positively associated with urinary iAs concentration after adjusting for the confounding effects of age, employed years, body mass index (BMI), smoking, alcohol, and seafood consumption in recent 3 days. Urinary TNF-α and TGF-α levels were also significantly positively associated with urinary iAs concentration, and SMI. TGF-α level was negatively associated with age after adjusting for the confounding effects. Consistent with the results in vivo, mRNA expressions of TNF-α, TGF-α, and IL-8 and protein expressions of TGF-α, TGF-β1, and IL-8 were significantly elevated in SV-HUC-1 cells after exposure to lower concentrations of arsenite for 24h as compared to the control group. These data indicated that arsenic increased the secretion of inflammatory factors and IL-8, TNF-α, and TGF-α expression may be a useful biomarker of the effect of arsenic exposure.

Prenatal arsenic exposure and shifts in the newborn proteome: interindividual differences in tumor necrosis factor (TNF)-responsive signaling

Exposure to inorganic arsenic (iAs) early in life is associated with adverse health effects in infants, children, and adults, and yet the biological mechanisms that underlie these effects are understudied. The objective of this research was to examine the proteomic shifts associated with prenatal iAs exposure using cord blood samples isolated from 50 newborns from Gómez Palacio, Mexico. Levels of iAs in maternal drinking water (DW-iAs) and the sum of iAs and iAs metabolites in maternal urine (U-tAs) were determined. Cord blood samples representing varying iAs exposure levels during the prenatal period (DW-iAs ranging from <1 to 236 μg As/l) were analyzed for altered expression of proteins associated with U-tAs using a high throughput, antibody-based method. A total of 111 proteins were identified that had a significant association between protein level in newborn cord blood and maternal U-tAs. Many of these proteins are regulated by tumor necrosis factor and are enriched in functionality related to immune/inflammatory response and cellular development/proliferation. Interindividual differences in proteomic response were observed in which 30 newborns were "activators," displaying a positive relationship between protein expression and maternal U-tAs. For 20 "repressor" newborns, a negative relationship between protein expression level and maternal U-tAs was observed. The activator/repressor status was significantly associated with maternal U-tAs and head circumference in newborn males. These results may provide a critical groundwork for understanding the diverse health effects associated with prenatal arsenic exposure and highlight interindividual responses to arsenic that likely influence differential susceptibility to adverse health outcomes.

Immunomodulatory role of Emblica officinalis in arsenic induced oxidative damage and apoptosis in thymocytes of mice

BACKGROUND

Arsenic is widely distributed in the environment and has been found to be associated with the various health related problems including skin lesions, cancer, cardiovascular and immunological disorders. The fruit extract of Emblica officinalis (amla) has been shown to have anti-oxidative and immunomodulatory properties. In view of increasing health risk of arsenic, the present study has been carried out to investigate the protective effect of amla against arsenic induced oxidative stress and apoptosis in thymocytes of mice.

METHODS

Mice were exposed to arsenic (sodium arsenite 3 mg/kg body weight p.o.) or amla (500 mg/kg body weight p.o.) or simultaneously with arsenic and amla for 28 days. The antioxidant enzyme assays were carried out using spectrophotometer and generation of ROS, apoptotic parameters, change in cell cycle were carried out using flow cytometer following the standard protocols.

RESULTS

Arsenic exposure to mice caused a significant increase in the lipid peroxidation, ROS production and decreased cell viability, levels of reduced glutathione, the activity of superoxide dismutase, catalase, cytochrome c oxidase and mitochondrial membrane potential in the thymus as compared to controls. Increased activity of caspase-3 linked with apoptosis assessed by the cell cycle analysis and annexin V/PI binding was also observed in mice exposed to arsenic as compared to controls. Co-treatment with arsenic and amla decreased the levels of lipid peroxidation, ROS production, activity of caspase-3, apoptosis and increased cell viability, levels of antioxidant enzymes, cytochrome c oxidase and mitochondrial membrane potential as compared to mice treated with arsenic alone.

CONCLUSIONS

The results of the present study exhibits that arsenic induced oxidative stress and apoptosis significantly protected by co-treatment with amla that could be due to its strong antioxidant potential.

Arsenic exposure through drinking water increases the risk of liver and cardiovascular diseases in the population of West Bengal, India

BACKGROUND

Arsenic is a natural drinking water contaminant affecting 26 million people in West Bengal, India. Chronic arsenic exposure causes cancer, cardiovascular disease, liver disease, neuropathies and ocular diseases. The aims of the present study were to assess bioindicators of hepatocellular injury as indicated by the levels of liver enzymes, to determine the auto immune status, as indicated by the amounts of anti-nuclear antibodies (ANA) and anti-dsDNA antibodies in their serum, and to predict cardiovascular risk in the arsenic exposed population.

METHODS

Effect of chronic arsenic exposure on liver was determined by liver function tests. Autoimmune status was measured by measuring ANA and anti-dsDNA in serum. Inflammatory cytokines associated with increased cardiovascular disease risk, IL6, IL8 and MCP-1 were determined.

RESULTS

Our results indicated that serum levels of bilirubin, alanine transaminase, aspartate transaminase, alkaline phosphatase and ANA were increased in the arsenic exposed population. Serum levels of IL6 and IL8 also increased in the arsenic exposed group.

CONCLUSIONS

Chronic arsenic exposure causes liver injury, increases the serum levels of autoimmune markers and imparts increased cardiovascular risk.

Arsenite activates NFκB through induction of C-reactive protein

C-reactive protein (CRP) is an acute phase protein in humans. Elevated levels of CRP are produced in response to inflammatory cytokines and are associated with atherosclerosis, hypertension, cardiovascular disease and insulin resistance. Exposure to inorganic arsenic, a common environmental toxicant, also produces cardiovascular disorders, namely atherosclerosis and is associated with insulin-resistance. Inorganic arsenic has been shown to contribute to cardiac toxicities through production of reactive oxygen species (ROS) that result in the activation of NFκB. In this study we show that exposure of the hepatic cell line, HepG2, to environmentally relevant levels of arsenite (0.13 to 2 μM) results in elevated CRP expression and secretion. ROS analysis of the samples showed that a minimal amount of ROS are produced by HepG2 cells in response to these concentrations of arsenic. In addition, treatment of FvB mice with 100 ppb sodium arsenite in the drinking water for 6 months starting at weaning age resulted in dramatically higher levels of CRP in both the liver and inner medullary region of the kidney. Further, mouse Inner Medullary Collecting Duct cells (mIMCD-4), a mouse kidney cell line, were stimulated with 10 ng/ml CRP which resulted in activation of NFκB. Pretreatment with 10 nM Y27632, a known Rho-kinase inhibitor, prior to CRP exposure attenuated NFκB activation. These data suggest that arsenic causes the expression and secretion of CRP and that CRP activates NFκB through activation of the Rho-kinase pathway, thereby providing a novel pathway by which arsenic can contribute to metabolic syndrome and cardiovascular disease.

Age-related effects of sodium arsenite on splenocyte proliferation and Th1/Th2 cytokine production

Aging is associated with immune dysfunction and conditions such as inflamm-aging and immunosuppression. Arsenic, an environmental contaminant distributed worldwide, affects the immune system. This study tested the hypothesis that arsenic has distinct effects on T cell proliferation and the production of cytokines by activated T cells. Murine splenocytes from young (2 months) and aged (24-26 months) C57BL/6 mice were exposed to arsenite (As(3+)), the most toxic form of inorganic arsenic, and stimulated with concanavalin A (Con A) or anti-CD3 antibody. T cell proliferation decreased significantly in response to Con A and anti-CD3 at subtoxic doses of arsenite in splenocytes from both young and aged mice. Arsenite, added concurrently with Con A or anti-CD3, significantly inhibited the production of interleukin-2 (IL-2), interferon-γ (IFN-γ), and interleukin-4 (IL-4) by splenocytes from young mice and significantly reduced the production of IL-10 by splenocytes from aged mice. In contrast, the production of IL-2 and IL-4 by splenocytes from aged mice was only slightly affected by arsenite. The results show that arsenic exposure reduces the immune response in splenocytes. Moreover, this effect may be influenced by aging.