Exposure to short-chain chlorinated paraffins induces astrocyte activation via JAK2/STAT3 signaling pathway

Effects of environmentally relevant concentration of short-chain chlorinated paraffins on BV2 microglia activation and lipid metabolism, implicating altered neurogenesis

Short-chain chlorinated paraffins (SCCPs), a class of persistent organic pollutants, have been found to cause diverse organ and systemic toxicity. However, little is known about their neurotoxic effects. In this study, we exposed BV2, a mouse microglia cell line, to environmentally relevant concentration of SCCPs (1 μg/L, 10 μg/L, 100 μg/L) for 24 h to investigate their impacts on the nervous system. Our observations revealed that SCCPs induced the activation of BV2 microglia, as indicated by altered morphology, stimulated cell proliferation, enhanced phagocytic and migratory capabilities. Analysis at the mRNA level confirmed the activation status, with the downregulation of TMEM119 and Tgfbr1, and upregulation of Iba1 and CD11b. The upregulated expression of genes such as cenpe, mki67, Axl, APOE and LPL also validated alterations in cell functions. Moreover, BV2 microglia presented an M2 alternative phenotype upon SCCPs exposure, substantiated by the reduction of NF-κB, TNF-α, IL-1β, and the elevation of TGF-β. Additionally, SCCPs caused lipid metabolic changes in BV2 microglia, characterized by the upregulations of long-chain fatty acids and acylcarnitines, reflecting an enhancement of β-oxidation. This aligns with our findings of increased ATP production upon SCCPs exposure. Intriguingly, cell activation coincided with elevated levels of omega-3 polyunsaturated fatty acids. Furthermore, activated microglial medium remarkably altered the proliferation and differentiation of mouse neural stem cells. Collectively, exposure to environmentally relevant concentrations of SCCPs resulted in activation and lipid metabolic alterations in BV2 microglia, potentially impacting neurogenesis. These findings provide valuable insights for further research on the neurotoxic effect of SCCPs.

Enriched Environment Inhibits Neurotoxic Reactive Astrocytes via JAK2-STAT3 to Promote Glutamatergic Synaptogenesis and Cognitive Improvement in Chronic Cerebral Hypoperfusion Rats

Chronic cerebral hypoperfusion (CCH) is a primary contributor to cognitive decline in the elderly. Enriched environment (EE) is proved to improve cognitive function. However, mechanisms involved remain unclear. The purpose of the study was exploring the mechanisms of EE in alleviating cognitive deficit in rats with CCH. To create a rat model of CCH, 2-vessel occlusion (2-VO) surgery was performed. All rats lived in standard or enriched environments for 4 weeks. Cognitive function was assessed using the novel object recognition test and Morris water maze test. The protein levels of glutamatergic synapses, neurotoxic reactive astrocytes, reactive microglia, and JAK2-STAT3 signaling pathway were measured using Western blot. The mRNA levels of synaptic regulatory factors, C1q, TNF-α, and IL-1α were identified using quantitative PCR. Immunofluorescence was used to detect glutamatergic synapses, neurotoxic reactive astrocytes, and reactive microglia, as well as the expression of p-STAT3 in astrocytes in the hippocampus. The results demonstrated that the EE mitigated cognitive impairment in rats with CCH and enhanced glutamatergic synaptogenesis. EE also inhibited the activation of neurotoxic reactive astrocytes. Moreover, EE downregulated microglial activation, levels of C1q, TNF-α and IL-1α and phosphorylation of JAK2 and STAT3. Our results suggest that inhibition of neurotoxic reactive astrocytes may be one of the mechanisms by which EE promotes glutamatergic synaptogenesis and improves cognitive function in rats with CCH. The downregulation of reactive microglia and JAK2-STAT3 signaling pathway may be involved in this process.

Protective Effect of Alkaline Mineral Water on Calcium Oxalate-Induced Kidney Injury in Mice

Background

Kidney stone disease induces chronic renal insufficiency by crystal-induced renal tubular epithelial cell injury. It has been reported that the prevalence of kidney stone disease is increasing, accompanied by the high recurrence rate. Alkaline mineral water has been reported to possess beneficial effects to attenuate inflammation. Here, we explored the potential protective effects and underlying mechanisms of alkaline mineral water against calcium oxalate-induced kidney injury.

Methods

We performed the mice kidney stone model by administering glyoxylate at 100 mg/kg once daily for 7 days. To assess the effects of alkaline mineral water on oxalate-induced kidney injury, mice drank different water (distilled water, natural mineral water at pH = 8.0, as well as natural mineral water at pH = 9.3) for 7 days, respectively, followed by glyoxylate exposure. After collection, crystal formation, kidney injury and cell apoptosis, fibrosis, oxidative stress, as well as inflammation were measured.

Results

Our results showed that glyoxylate treatment led to kidney crystal formation and fibrosis, which can be attenuated by drinking alkaline mineral water. Furthermore, alkaline mineral water also reduced kidney injury and cell apoptosis, oxidative stress, and inflammation.

Conclusion

Alkaline mineral water supplement prevents progression of glyoxylate-induced kidney stones through alleviating oxidative stress and inflammation.

Concentrations and homologue patterns of SCCPs and MCCPs in the serum of the general population of adults in Hangzhou, China

Due to their ubiquitous presence in the environment and humans, chlorinated paraffins (CPs) are a major environmental and public health concern. CPs are known to persist, bioaccumulate and potentially threaten human health, but reports on their internal exposure in the adult general population are still scarce. In this study, serum samples collected from adults living in Hangzhou, China, were quantified for SCCPs and MCCPs using GC-NCI-MS methods. A total of 150 samples were collected and subjected to analysis. ∑SCCPs were detected in 98% of the samples with a median concentration of 721 ng/g lw. MCCPs were found in all serum samples with a median concentration of 2210 ng/g lw, indicating that MCCPs were the dominant homologous group. For SCCPs and MCCPs, ∑C₁₀ and ∑C₁₄ were found to be the dominant carbon chain length homologues. Our results showed that age, BMI and lifestyle were not found to be significantly associated with internal exposure to CPs for the samples in this study. Based on PCA analysis, an age-specific distribution of CP homologues was observed. This suggests that internal exposure to CPs in the general population is related to exposure scenarios and history. The results of this study may contribute to a better understanding of the internal exposure to CPs in the general population and may provide a direction for the investigation of the source of exposure to CPs in the environment and daily life.

The potential health risks of short-chain chlorinated paraffin: A mini-review from a toxicological perspective

Short-chain chlorinated paraffins (SCCPs) are ubiquitously distributed in various environmental matrics due to their wide production and consumption globally in the past and ongoing production and use in some developing countries. SCCPs have been detected in various human samples including serum, milk, placenta, nail, and hair, and internal SCCP levels were found to be positively correlated with biomarkers of some diseases. While the environmental occurrence has been reported in a lot of studies, the toxicity and underlying molecular mechanisms of SCCPs remain largely unknown. The current tolerable daily intakes (TDIs) recommended by the world health organization/international programme on chemical safety (WHO/IPCS, 100 μg/kg bw/d) and the UK Committee on Toxicity (COT, 30 μg/kg bw/d) were obtained based on a no observed adverse effect level (NOAEL) of SCCP from the repeated-dose study (90 d exposure) in rodents performed nearly 40 years ago. Importantly, the health risks assessment of SCCPs in a variety of studies has shown that the estimated daily intakes (EDIs) may approach and even over the established TDI by UK COT. Furthermore, recent studies revealed that lower doses of SCCPs could also result in damage to multiple organs including the liver, kidney, and thyroid. Long-term effects of SCCPs at environmental-related doses are warranted.

Assessment of silicone wristbands for monitoring personal exposure to chlorinated paraffins (C8-36): A pilot study

Chlorinated paraffins (CPs) are a major environmental concern due to their ubiquitous presence in the environment. Since human exposure to CPs can significantly differ among individuals, it is essential to have an effective tool for monitoring personal exposure to CPs. In this pilot study, silicone wristbands (SWBs) were employed as a personal passive sampler to measure time-weighted average exposure to CPs. Twelve participants were asked to wear a pre-cleaned wristband for a week during the summer of 2022, and three field samplers (FSs) in different micro-environments were also deployed. The samples were then analyzed for CP homologs by LC-Q-TOFMS. In worn SWBs, the median concentrations of quantifiable CP classes were 19 ng/g wb, 110 ng/g wb, and 13 ng/g wb for ∑SCCPs, ∑MCCPs, and ∑LCCPs (C_18-20), respectively. For the first time, lipid content is reported in worn SWBs, which could be a potential impact factor in the kinetics of the accumulation process for CPs. Results showed that micro-environments were key contributors to dermal exposure to CPs, while a few outliers suggested other sources of exposure. CP exposure via dermal contact showed an increased contribution and thus poses a nonnegligible potential risk to humans in daily life. Results presented here provide proof of concept of the use of SWBs as a cheap and non-invasive personal sampler in exposure studies.

Chronic oral exposure to short chain chlorinated paraffins induced testicular toxicity by promoting NRF2-mediated oxidative stress

As a widespread environmental contaminant, short chain chlorinated paraffins (SCCPs) has attracted great attention. However, the toxicity of SCCPs on male reproductive system remains ambiguous. In this study, we treated mice with SCCPs by gavage and investigated the toxic effects of SCCPs on testis. According to the results, the sperm parameters of mice were significantly reduced after exposure to 1, 10, 100 mg/kg body mass per day SCCPs for 35 days. SCCPs resulted in disorderly arranged seminiferous epithelium and increased apoptotic cells in testes. Both in vivo and in vitro experiments indicated that the oxidative stress was induced after SCCPs exposure, and dysfunction of nuclear factor erythroid-related factor (NRF2) signaling pathway played a role in this process. Moreover, resveratrol, an NRF2 activator, could alleviate the damage of SCCPs onmale reproductive system. Our study indicated that oxidative stress is the key point for explaining the testicular toxicity caused by SCCPs, and NRF2 could be used as a potential target for clinical treatment to alleviate the reproductive toxicity induced by SCCPs.