Evaluation of the immunomodulatory effects of C9-13-CPs in macrophages.

Short-chain chlorinated paraffins (SCCPs) have been listed as a new class of persistent organic pollutants by the Stockholm Convention. SCCPs exhibit carcinogenic-, endocrine-, and metabolism-disrupting effects. However, the knowledge of the immunomodulatory effects of SCCPs and their underlying mechanisms, especially in specific immune cells, remains limited. In addition to SCCPs, C9-13-CPs have also been detected in humans. In this study, murine RAW264.7 macrophages were exposed to C9-13-CPs at environmentally relevant concentrations to investigate whether or how C9-13-CPs exhibit immunomodulatory effects. The results showed that the exposure of RAW264.7 cells to C9-13-CPs increased cell viability, as assayed by MTT analysis at 490 nm, and also promoted cell proliferation, as indicated by EdU uptake assay, which was measured at excitation and emission wavelengths of 488 and 512 nm, respectively. In addition, exposure to C9-13-CPs not only led to elevated ATP level and intracellular Ca2+ level but also caused AMPK signaling activation and NF-κB signaling inhibition. Moreover, molecular docking showed that the ß2-AR receptor could bind to C9-13-CPs. Taken together, these results suggest that the immune dysfunction of RAW264.7 cells caused by C9-13-CPs is closely related to the ß2-AR/AMPK/NF-κB signaling axis.

ß -Cypermethrin promotes the adipogenesis of 3T3-L1 cells via inducing autophagy and shaping an adipogenesis-friendly microenvironment.

The toxicity of synthetic pyrethroids has garnered attention, and studies have revealed that pyrethroids promote fat accumulation and lead to obesity in mice. Nevertheless, the effect of ß-cypermethrin (ß-CYP) on adipogenesis and its underlying mechanism remains largely unknown. In this study, mouse embryo fibroblasts 3T3-L1 cells were exposed to ß-CYP, and the cell viability, intracellular reactive oxygen species (ROS) level, autophagy, and adipogenesis were assessed to investigate the roles of oxidative stress and autophagy in the toxic effects of ß-CYP on adipogenesis. The results demonstrated that treatment with 100 µΜ ß-CYP elevated the ROS level, decreased mitochondrion membrane potential, stimulated autophagy, and enhanced the adipogenesis induced by the mixture of insulin, dexamethasone, and 3-isobutyl-1-methylxanthine. However, co-treatment with N-acetyl-L-cysteine partially blocked the abovementioned effects of ß-CYP in 3T3-L1 cells. In addition, co-treatment with rapamycin, an autophagy agonist, enhanced the inductive effect of ß-CYP on adipogenesis, whereas co-treatment with 3-methyladenine blocked the enhancement of adipogenesis caused by ß-CYP. Moreover, ß-CYP also altered the microenvironment of 3T3-L1 cells to an adipogenesis-friendly one by reducing the extracellular expression of miR-34a, suggesting that the culture media of ß-CYP-treated 3T3-L1 cells could shift macrophages to M2 type. Taken together, the data obtained in the present study demonstrated that ß-CYP promoted adipogenesis via oxidative stress-mediated autophagy disturbance, and it caused macrophage M2 polarization via the alteration of miR-34a level in the microenvironment. The study demonstrated the adipogenesis-promoting effect of ß-CYP and unveiled the potential mechanism.

ß-Cypermethrin Alleviated the Inhibitory Effect of Medium from RAW 264.7 Cells on 3T3-L1 Cell Maturation into Adipocytes.

Studies have elucidated that pyrethroids induce adipogenesis. It is also known that macrophages can affect the homeostasis of adipose tissue. However, whether and how the ß-cypermethrin (ß-CYP)-mediated inhibition of the macrophages affects adipogenesis remain unknown. To explore the effects of ß-CYP on adipogenesis through modulating the function of macrophages, 3T3-L1 cells, a preadipocyte cell line, were exposed to culture medium from either RAW 264.7 cells, a macrophage cell line (RM), or ß-CYP-treated RAW 264.7 cells (CRM). CRM decreased the inhibitory effects of RM treatment on cell proliferation and adipogenesis, as lipid accumulation, the CEBPA content, and Fasn and Acaca expression in 3T3-L1 cells were higher following CRM treatment than following RM treatment through the higher levels of the demethylated CEBPA promoter in 3T3-L1 cells. However, the medium from ß-CYP- and N-acetyl-L-cysteine-cotreated RAW 264.7 cells (CNRM) partially restored the inhibitory effects of RAW 264.7 cells on 3T3-L1 cells that had been reduced by CRM, indicating that ß-CYP might reduce the cytotoxicity and inhibitory effects of RAW 264.7 cells on the adipogenesis of 3T3-L1 cells through elevating ROS levels in RAW 264.7 cells. Moreover, exposure to ß-CYP downregulated the TNF-α secretion in RAW 264.7 cells. In conclusion, these data demonstrated that ß-CYP affected the function of RAW 264.7 cells, alleviating their inhibitory effects on adipogenesis and CEBPA demethylation in 3T3-L1 cells. ß-CYP might achieve these effects through downregulating the secretion of TNF-α via elevating ROS levels in RAW 264.7 cells. Our experiments provide a new perspective on the obesogenic effect of pyrethroids.

Environmentally relevant doses of tetrabromobisphenol A (TBBPA) cause immunotoxicity in murine macrophages.

TBBPA is one of the main brominated flame retardants and is ubiquitous in the environment. TBBPA can directly encounter immune cells via the bloodstream, posing potential immunotoxicity. To understand the immunomodulating effect of TBBPA on macrophages, the murine macrophages, RAW 264.7, were exposed to TBBPA at environmentally relevant concentrations (1-100 nM). The results showed that TBBPA at the selected concentrations did not alter cell viability of RAW 264.7 cells with or without LPS stimulation. TBBPA upregulated the expression of pro-inflammatory cytokines, including IL-1ß, IL-6, and TNF-α, whereas it attenuated the LPS-stimulated expression of these pro-inflammatory cytokines, and the expression of anti-inflammatory cytokines, including IL-4, IL-10, and IL-13. In addition, TBBPA reduced the mRNA levels of antigen-presenting-related genes, including H2-K2, H2-Aa, Cd80, and Cd86. Moreover, TBBPA impaired the phagocytic activity of macrophages. Furthermore, exposure to TBBPA significantly elevated the protein levels of phosphorylated NF-κB p65 (p-p65), while it reduced LPS-stimulated p-p65 protein levels. DCFH-DA staining assays showed that TBBPA caused a slight but significant elevation in reactive oxygen species levels. The data obtained in the present study demonstrated that exposure to environmentally relevant concentrations of TBBPA posed immunotoxicity in macrophages and unveiled a potential health risk of TBBPA.

The environmental distribution and toxicity of short-chain chlorinated paraffins and underlying mechanisms: Implications for further toxicological investigation.

Short-chain chlorinated paraffin (SCCP) pollution has become a global threat. Much attention has been paid to their environmental occurrence and toxicity. In this review, we summarized the wide distribution of SCCPs in various environmental matrices and biota, including human beings. Toxicokinetics and the toxicities of SCCPs, including lethality, hepatotoxicity, developmental toxicity, carcinogenicity, endocrine- and metabolism-disrupting effects, and immunomodulatory effects have been considered. The mechanisms of SCCP toxicity are mainly related to oxidative stress, metabolic disturbance, endocrine disruption and binding to biomacromolecules. In the future, further studies of SCCPs should focus on searching for their novel toxicity targets, and uncovering their toxic effects using transcriptomics, proteomics, metabolomics, and mutigenerational toxicity.