A role of connexin 43 on the drug-induced liver, kidney, and gastrointestinal tract toxicity with associated signaling pathways

The role of enhanced expression of Cx43 in patients with ulcerative colitis

The pathogenesis of ulcerative colitis (UC) involves chronic inflammation of the submucosal layer and disruption of epithelial barrier function within the gastrointestinal tract. Connexin 43 (Cx43) has been implicated in the pathogenesis of intestinal inflammation and its associated carcinogenic effects. However, a comprehensive analysis of Cx43's role in mucosal and peripheral immunity in patients with UC is lacking. In this study, the colon tissues of patients with UC exhibited severe damage to the intestinal mucosal barrier, resulting in a significant impairment of junctional communication as observed by transmission electron microscopy. The mRNA expression of Cx43 was found to be significantly elevated in the UC group compared to the control group, as determined using the Affymetrix expression profile chip and subsequently validated using qRT-PCR. The immunofluorescence analysis revealed a significantly higher mean fluorescence intensity of Cx43 in the UC group compared to the control group. Additionally, Cx43 was observed in both the cell membrane and nucleus, providing clear evidence of nuclear translocation. The proportion of Cx43 in the UC group for CD4+ and CD8+ T lymphocytes was increased in the control group, but only the proportion of Cx43 for CD8+ T lymphocytes showed significant difference by flow cytometry. The involvement of Cx43 in the pathogenesis of UC and its potential role in mucosal immunity warrants further investigation, as it holds promise as a prospective biomarker and therapeutic target for this condition. The proportion of Cx43 in the UC group for CD4+ and CD8+ T lymphocytes was increased in the control group, but only the proportion of Cx43 for CD8+ T lymphocytes showed a significant difference.

Nano-selenium alleviates cadmium-induced neurotoxicity in cerebrum via inhibiting gap junction protein connexin 43 phosphorylation

Cadmium (Cd) as a ubiquitous toxic heavy metal is reported to affect the nervous system. Selenium (Se) has been shown to have antagonistic effects against heavy metal toxicity. In addition, it shows potential antioxidant and anti-inflammatory properties. Thus, the purpose of this study was to determine the possible mechanism of brain injury after high Cd exposure and the mitigation of Nano-selenium (Nano-Se) against Cd-induced brain injury. In this study, the Cd-treated group showed a decrease in the number of neurons in brain tissue, swelling of the endoplasmic reticulum and mitochondria, and the formation of autophagosomes. Nano-Se intervention restored Cd-caused alterations in neuronal morphology, endoplasmic reticulum, and mitochondrial structure, thereby reducing neuronal damage. Furthermore, we found that some differentially expressed genes were involved in cell junction and molecular functions. Subsequently, we selected eleven (11) related differentially expressed genes for verification. The qRT-PCR results revealed the same trend of results as determined by RNA-Seq. Our findings also showed that Nano-Se supplementation alleviated Cx43 phosphorylation induced by Cd exposure. Based on immunofluorescence colocalization it was demonstrated that higher expression of GFAP and lower expressions of Cx43 were restored by Nano-Se supplementation. In conclusion, the data presented in this study establish a direct association between the phosphorylation of Cx43 and the occurrence of autophagy and neuroinflammation. However, it is noteworthy that the introduction of Nano-Se supplementation has been observed to mitigate these alterations. These results elucidate the relieving effect of Nano-Se on Cd exposure-induced brain injury.

Zinc and L-carnitine combination with or without methotrexate prevents intestinal toxicity during arthritis treatment via Nrf2/Sirt1/Foxo3 pathways: an In vivo and molecular docking approach

Methotrexate (MTX) is an antifolate that is inescapable and widely used to treat autoimmune diseases and is the gold standard medicine for the arthritic condition. Despite its importance, it is more prone to gastrointestinal toxicity, which is most common in arthritis patients during MTX treatment. Combination therapies are required to ensure MTX's antiarthritic activity while providing gastrointestinal protection. Zinc (Zn) and L-carnitine (Lc) are well-known potent antioxidants and anti-inflammatory supplements with promising results in pre-clinical studies. Arthritis was induced in Wistar rat's ankles with Freund's adjuvant and treated with either MTX (2.5 mg/kg b.w per week for two weeks) or Zn (18 mg/kg b.w. per day) Lc (200 mg/kg b.w. per day) individually or in combination (MTX + Zn Lc). The antiarthritic effects were evaluated by body weight, paw volume, ankle tissue, and joint histopathology. At the same time, anti-toxicity/gastrointestinal protective activity was examined by tissue oxidative stress markers, antioxidants, mitochondrial function, inflammatory mediators, and antioxidant signaling proteins and their binding mechanism. Repercussions of MTX intoxication induced upregulation of oxidative stress markers, antioxidant depletion, ATP depletion, decreased expression of Nrf2/Sirt1/Foxo3, and the overexpression of inflammatory mediators attenuated by co-treatment with Zn Lc. Zn Lc markedly mitigated MTX-instigated intestinal injury by activating antioxidant signaling mechanisms Nrf2/Sirt1/Foxo3 signaling and tissue architectural anomalies and exhibited an enhanced antiarthritic effect. In conclusion, we report that Zn Lc and MTX combination could presumably protect the intestine from low-dose MTX which managed arthritis but induced severe intestinal damage with increased inflammation and downregulated Nrf2/Sirt1/Foxo3 pathway.

18-α-glycyrrhetinic acid alleviates oxidative damage in periodontal tissue by modulating the interaction of Cx43 and JNK/NF-κB pathways

Objective: Periodontitis is a common chronic inflammatory disease in which oxidative stress is one of the key pathogenic factors. Connexin43 (Cx43) is the most critical and widely distributed connexin isoform. When the organism undergoes a severe and sustained stress response, Cx43-mediated gap junctions (GJs) are believed to underlie the biology of tissue injury exacerbation and amplification. Notably, 18-α-glycyrrhetinic acid (GA) is a classical pharmacological inhibitor of GJs and has antioxidant potential. However, the regulatory role of GA in the redox signaling of periodontal tissues and the potential mechanisms of Cx43 in the pathogenesis of periodontitis remain uncertain. Methods: In this study, we evaluated the effects and mechanisms of GA in alleviating oxidative damage of periodontal tissues and cells by constructing an H2O2-induced oxidative stress model in human periodontal ligament cells (hPDLCs) and a periodontitis model in rats. Results: Cellular experiments showed that GA effectively attenuated H2O2-induced oxidative damage in hPDLCs by inhibiting the expression and function of Cx43. In addition, pretreatment of hPDLCs with either GA or SP600125 (a JNK inhibitor) inhibited the Cx43/JNK/NF-κB pathway, restored cell viability, and reduced apoptosis. Animal experiment results showed that GA intervention reduced alveolar bone resorption and periodontal tissue destruction, inhibited osteoclast differentiation, improved mitochondrial structural abnormalities and dysfunction in periodontal tissue, and decreased oxidative stress levels and apoptosis in rats with periodontitis. Conclusion: Overall, our findings suggest that the Cx43/JNK/NF-κB pathway may play a vital role to promote periodontitis progression, while GA reduces oxidative stress and apoptosis by inhibiting the interaction of Cx43 and JNK/NF-κB pathways, thus alleviating oxidative damage in the periodontal tissues.

Caesalpinia bonducella mitigates oxidative damage by paracetamol intoxication in the kidney and intestine via modulating pro/anti-inflammatory and apoptotic signaling: an In vivo mechanistic insight

Protracted use of paracetamol at therapeutic/toxic doses readily induces major organ toxicity and poor clinical efficacy. Caesalpinia bonducella seeds possess a diverse range of biological and therapeutic activities. Thus, our study aimed to scrutinize the toxic effects of paracetamol and the potential renal and intestinal protective effects of Caesalpinia bonducella seed extract (CBSE). To Wistar rats, CBSE was administered for 8 days (300 mg/kg, p.o.) with or without paracetamol (2000 mg/kg, p.o.) on the 8th day. Pertinent toxicity assessments in the kidney and intestine were analyzed at the end of the study. The CBASE's phytochemical components were examined using gas chromatography-mass spectrometry (GC-MS). After the study period, study findings evidenced that paracetamol intoxication induced elevation of renal enzyme indicators, oxidative damage, imbalance with the pro/anti-inflammatory production and pro/anti-apoptotic mediators, and tissue injury; all repercussions were alleviated by pre-treatment with CBASE. CBASE considerably reduced (P < 0.05) paracetamol-induced kidney and intestine injury by limiting caspase-8/3 signaling and amplification of inflammation in renal and intestinal tissue by significantly reducing pro-inflammatory cytokine production. As per the GC-MS report, three main bioactive components-Piperine, Isocaryophyllene, and Tetradec-13-en-11-yn-1-ol were predominant and have protective activities. Our study ascertains that CBSE pre-treatment exerts potent renal and intestine protection against paracetamol intoxication. Thus, CBSE could be a prospective therapeutic candidate for protecting the kidney and intestine from the severity of paracetamol intoxication.

Plasma exosome-derived connexin43 as a promising biomarker for melanoma patients

BACKGROUND

To examine the levels of exosome-derived connexin 43 (Cx43) in plasma and estimate its forecast value in patients with melanoma.

METHODS

We measured the plasma exosome-derived Cx43 levels in the plasma of 112 melanoma patients and 50 healthy controls.

RESULTS

The plasma exosome-derived Cx43 levels in patients with melanoma were substantially downregulated as opposed to the levels in healthy controls (P < 0.001). Kaplan-Meier analysis indicated that overall survival (OS) and disease-free survival (DFS) were poorer in patients with melanoma who exhibited lower levels of plasma exosome-derived Cx43 (both P < 0.001). The levels of plasma exosome-derived Cx43 were considerably elevated in patients with melanoma whose tumor was situated in the skin, tumor size < 10 cm, with Clark level I-III, TNM stages IIb-IV, and had no lymph node metastasis as opposed to patients whose tumor was situated in the viscera or mucosa, tumor size ≥ 10 cm, Clark level IV-V, TNM stages IIb-IV and had lymph node metastasis (all P < 0.05). The receiver operating characteristic (ROC) of plasma exosome-derived Cx43 for forecasting 5-year DFS in patients with melanoma was 0.78 (95% confidence interval (CI): 0.70-0.86), with a specificity of 77.78% and a sensitivity of 81.55%. The ROC of plasma exosome-derived Cx43 for forecasting 5-year OS of patients with melanoma was 0.77 (95% CI: 0.68-0.84), with a specificity of 80.0% and sensitivity of 65.98%.

CONCLUSION

The overall findings indicated that the levels of plasma exosome-derived Cx43 in patients with melanoma were considerably downregulated. It can therefore be inferred that the levels of plasma exosome-derived Cx43 might be a prospective prognostic indicator for 5 5-year OS and 5-year DFS of patients with melanoma.

Identification of Candidate Therapeutic Genes for More Precise Treatment of Esophageal Squamous Cell Carcinoma and Adenocarcinoma

The standard therapy administered to patients with advanced esophageal cancer remains uniform, despite its two main histological subtypes, namely esophageal squamous cell carcinoma (SCC) and esophageal adenocarcinoma (AC), are being increasingly considered to be different. The identification of potential drug target genes between SCC and AC is crucial for more effective treatment of these diseases, given the high toxicity of chemotherapy and resistance to administered medications. Herein we attempted to identify and rank differentially expressed genes (DEGs) in SCC vs. AC using ensemble feature selection methods. RNA-seq data from The Cancer Genome Atlas and the Fudan-Taizhou Institute of Health Sciences (China). Six feature filters algorithms were used to identify DEGs. We built robust predictive models for histological subtypes with the random forest (RF) classification algorithm. Pathway analysis also be performed to investigate the functional role of genes. 294 informative DEGs (87 of them are newly discovered) have been identified. The areas under receiver operator curve (AUC) were higher than 99.5% for all feature selection (FS) methods. Nine genes (i.e., ERBB3, ATP7B, ABCC3, GALNT14, CLDN18, GUCY2C, FGFR4, KCNQ5, and CACNA1B) may play a key role in the development of more directed anticancer therapy for SCC and AC patients. The first four of them are drug targets for chemotherapy and immunotherapy of esophageal cancer and involved in pharmacokinetics and pharmacodynamics pathways. Research identified novel DEGs in SCC and AC, and detected four potential drug targeted genes (ERBB3, ATP7B, ABCC3, and GALNT14) and five drug-related genes.

Connexin 43 Expression in Cutaneous Biopsies of Lupus Erythematosus

INTRODUCTION

Gap junctions are channels between adjacent cells formed by connexins (Cxs). Cxs also form hemichannels that connect the cell with its extracellular milieu. These channels allow the transport of ions, metabolites, and small molecules; therefore, Cxs, and more specifically, connexin (Cx) 43 has been demonstrated to be in control of several crucial events such as inflammation and cell death.

MATERIAL AND METHODS

We examined the immunostaining of Cx43 in the endothelia of the cutaneous blood vessels of biopsies from 28 patients with several variants of lupus erythematosus.

RESULTS

In 19 cases (67.86%), staining of more than half of the dermal vessels including both vessels of the papillary and of the reticular dermis was identified. Only in 4 cases (14.28%), less than 25% of the vessels in the biopsy showed expression of the marker.

CONCLUSIONS

Our results suggest a role of Cx43 in regulating the endothelial activity in lupus erythematosus, which also opens a door for targeted therapeutic options.

Isovitexin protects against acute liver injury by targeting PTEN, PI3K and BiP via modification of m6A

Isovitexin (IVT) has been shown to have a potential therapeutic effect on acute liver injury (ALI), but its underlying mechanisms especially the targets remain unclear, which was investigated in the present study. Briefly, the targets of IVT were predicted by bioinformatics and then were verified by multiple examinations using molecular docking, cellular thermal shift assay (CETSA), and Lipopolysaccharide/D-Galactosamine (LPS/D-GalN)-induced ALI animal model. The bioinformatic analysis predicted that the target genes of IVT against ALI were enriched into the PI3K/Akt and ERS-related pathways, in which, molecular docking and CETSA examination verified that the binding sites of IVT likely were PTEN, PI3K and BiP. Furthermore, the possible targets were also verified by animal experiments. The results revealed that IVT significantly ameliorated the hepatic injury, as evidenced by the attenuation of histopathological changes and the reduction in serum aminotransferase and total bilirubin activities. In addition, IVT treatment led to the reduction of PTEN, BiP and ERS-related targets expressions, as well as the elevation of PI3K, Akt and mTOR expressions. Notably, IVT significantly decreased total hepatic m6A level and m6A enrichment of PTEN and BiP, suggesting IVT regulated PTEN and BiP by modulating m6A modification. To sum up, the results indicate that IVT significantly ameliorates ALI, which is attributed to its ability to regulate the PI3K/Akt pathway and ERS by targeting PTEN, PI3K and BiP via modification of m6A. Our finding demonstrates that IVT may be a promising natural medicine for the treatment of ALI.

Nephroprotective effect of magnesium isoglycyrrhizinate against arsenic trioxide‑induced acute kidney damage in mice

Magnesium isoglycyrrhizinate (MgIG) has anti-inflammatory, antioxidative, antiviral and anti-hepatotoxic effects. However, protective effects of MgIG against renal damage caused by arsenic trioxide (ATO) have not been reported. The present study aimed to clarify the protective function of MgIG on kidney damaged induced by ATO. Other than the control group and the group treated with MgIG alone, mice were injected intraperitoneally with ATO (5 mg/kg/day) for 7 days to establish a mouse model of kidney damage. On the 8th day, blood and kidney tissue were collected and the inflammatory factors and antioxidants levels in the kidney tissue and serum were measured. The expression of protein levels of caspase-3, Bcl-2, Bax, Toll-like receptor-4 (TLR4) and nuclear factor-κB (NF-κB) were determined via western blot analysis. In the renal tissue of mice, ATO exposure dramatically elevated markers of oxidative stress, apoptosis and inflammation. However, MgIG could also restore the activities of urea nitrogen and creatinine to normal levels, decrease the malondialdehyde level and reactive oxygen species formation and increase superoxide dismutase, catalase and glutathione activities. MgIG also ameliorated the morphological abnormalities generated by ATO, reduced inflammation and apoptosis and inhibited the TLR4/NF-κB signaling pathway. In conclusion, MgIG may mitigate ATO-induced kidney damage by decreasing apoptosis, oxidative stress and inflammation and its mechanism may be connected to the inhibition of TLR4/NF-κB signaling.

Downregulation of Cx43 reduces cisplatin-induced acute renal injury by inhibiting ferroptosis

Ferroptosis is one of the main mechanisms involved in different forms of acute kidney injury (AKI), including cisplatin-induced AKI. However, it is not clear whether Cx43 has a regulatory effect on ferroptosis caused by cisplatin. In this study, we investigate the regulatory effects of Cx43 on cisplatin-induced ferroptosis and its mechanism. In vivo and in vitro studies showed that the expression level of Cx43 was significantly upregulated in the cisplatin-induced kidney injury model. In HK2 cells, cisplatin significantly induced ferroptosis. Adding shRNA-Cx43 and gap27 to the HK2 cells downregulated the expression of Cx43 and blocked the effects of cisplatin, resulting in a significantly improved survival rate of HK2 cells. Our primary data suggested that downregulating Cx43 not only inhibits ferroptosis, but also inhibits apoptosis. Through mechanistic studies, we confirmed that downregulating the expression of Cx43 by increasing SLC7A11 can increase the GSH content to inhibit cisplatin-induced ferroptosis. In vivo experiments showed that downregulation of Cx43 expression by gap27 reduced AKI in the animal model by inhibiting cisplatin-induced ferroptosis. Therefore, our results indicated that downregulation of Cx43 can inhibit ferroptosis by restoring the level of SLC7A11 in the system x_c‾ transporter and alleviate cisplatin-induced AKI.

Molecular toxicity of methotrexate in rheumatoid arthritis treatment: A novel perspective and therapeutic implications

Rheumatoid arthritis (RA) is an autoimmune inflammatory systematic complication which is a chronic disorder that severely affects bones and joints and results in the quality of life impairment. Methotrexate (MTX), an FDA-approved drug has maintained the standard of care for treating patients affected with RA. The mechanism of MTX includes the inhibition of purine and pyrimidine synthesis, suppression of polyamine accumulation, promotion of adenosine release, adhesion of the inflammatory molecules, and controlling of cytokine cascade in RA. The recommended dose for RA patients is 5-25 mg of MTX per week, depending on the severity of the disease but MTX has proven to be cytotoxic with side effects affecting various tissues when treating RA patients even with low doses over a prolonged period of time. The mechanism of such toxicity is not entirely understood. This review strives to understand it by correlating the different pathways, including MTX in folate metabolism, Sirt1/Nrf2/γ-gcs, and γ-gcs/CaSR-TNF-α/NF-kB signaling. In addition to this, the importance of targeted therapy combination with MTX on RA treatment and combinations approved from the clinical trials are also briefly discussed. Overall, this review elucidates the various MTX molecular mechanisms and toxicity at the molecular level, the limitations, and the scope for future directions.