Molecular mechanism of miR-203a targeting Runx2 to regulate thiram induced-chondrocyte development.

Thiram is a kind of organic compound, which is commonly used for sterilization, insecticidal and deodorization in daily life. Its toxicology has been broadly studied. Recently, more and more microRNAs have been shown to participate in the regulation of cartilage development. However, the potential mechanism by which microRNA regulates chondrocyte growth is still unclear. Our experiments have demonstrated that thiram can hamper chondrocytes development and cause a significant increase in miR-203a content in vitro and in vivo trials. miR-203a mimic significantly decrease in mRNA and protein expression of Wnt4, Runx2, COL2A1, ß-catenin and ALP, and significantly enhance the mRNA and protein levels of GSK-3ß. It has been observed that overexpression of miR-203a hindered chondrocytes development. In addition, Runx2 was confirmed to be a direct target of miR-203a by dual luciferase report gene assay. Transfection of si-Runx2 into chondrocytes reveals that significant downregulation of genes is associated with cartilage development. Overall, these results suggest that overexpression of miR-203a inhibits the expression of Runx2. These findings are conducive to elucidate the mechanism of chondrocytes dysplasia induced by thiram and provide new research ideas for the toxicology of thiram.

miR-181b-1-3p affects the proliferation and differentiation of chondrocytes in TD broilers through the WIF1/Wnt/ß-catenin pathway.

Thiram is a plant fungicide, its excessive use has exceeded the required environmental standards. It causes tibial dyschondroplasia (TD) in broilers which is a common metabolic disease that affects the growth plate of tibia bone. It has been studied that many microRNAs (miRNAs) are involved in the differentiation of chondrocytes however, their specific roles and mechanisms have not been fully investigated. The selected features of tibial chondrocytes of broilers were studied in this experiment which included the expression of miR-181b-1-3p and the genes related to WIF1/Wnt/ß-catenin pathway in chondrocytes through qRT-PCR, western blot and immunofluorescence. The correlation between miR-181b-1-3p and WIF1 was determined by dual luciferase reporter gene assay whereas, the role of miR-181b-1-3p and WIF1/Wnt/ß-catenin in chondrocyte differentiation was determined by mimics and inhibitor transfection experiments. Results revealed that thiram exposure resulted in decreased expression of miR-181b-1-3p and increased expression of WIF1 in chondrocytes. A negative correlation was also observed between miR-181b-1-3p and WIF1. After overexpression of miR-181b-1-3p, the expression of ACAN, ß-catenin and Col2a1 increased but the expression of GSK-3ß decreased. It was observed that inhibition of WIF1 increased the expression of ALP, ß-catenin, Col2a1 and ACAN but decreased the expression of GSK-3ß. It is concluded that miR-181b-1-3p can reverse the inhibitory effect of thiram on cartilage proliferation and differentiation by inhibiting WIF1 expression and activating Wnt/ß-catenin signaling pathway. This study provides a new molecular target for the early diagnosis and possible treatment of TD in broilers.

Aberrant peribiliary gland niche exacerbates fibrosis in primary sclerosing cholangitis and a potential therapeutic strategy.

Primary sclerosing cholangitis (PSC) is a rare but progressive and fatal autoimmune disease without clear pathogenesis and effective therapies. Peribiliary macrophage recruitment and peribiliary gland (PBG) proliferation and expansion have been associated with various cholangiopathies. This study aimed to evaluate the involvement of the PBG niche and macrophages in PSC progression, potential treatment strategies, and the underlying mechanism in acute and chronic experimental PSC. First, the upregulation of chemokines and fibrosis in PSC patients was confirmed via RNA-seq analysis. In vivo data illustrated that inflammation and fibrosis are the main characteristics, and recession of these can effectively interfere with PSC. Histopathological staining and RT-PCR revealed that more significant ductular reaction (DR) and PBG proliferation in the chronic PSC model, in which fibrosis mainly accumulated in the peribiliary area. In vitro, a transwell migration experiment showed that MCP-1 secreted by cholangiocytes in PBG niche, which recruited monocyte-derived macrophages (MoMFs) to the peribiliary area and promoted inflammation and fibrosis. Then, the luciferase assay and EMSA showed that POU6F1 could activate MCP-1 transcription. Furthermore, 18ß-Glycyrrhetinic acid (GA) reduced macrophages and fibrosis accumulated in the peribiliary, space and reduced PBG proliferation to benefit acute and chronic PSC models. Collectively, our results indicated that POU6F1 transcriptionally activates MCP-1, promoting the recruitment and infiltration of MoMFs and fibrosis into the PBG niche in PSC mouse models, and GA effectively suppressed the above phenotypes. These findings provide potential targets and a theoretical basis for the clinical treatment of PSC.

Kupffer cells play a crucial role in monocrotaline-induced liver injury by producing TNF-α.

Monocrotaline (MCT), an unsaturated pyrrolizidine alkaloid (PA) in plants, is mainly toxic to the lung and liver of mammals. As a commonly used tool for liver injury model, the mechanism of MCT hepatoxicity has still not been fully clarified. Kupffer cells (KCs) are the liver-resident macrophages and have various responses to different toxicants and liver damage. However, the role of KCs in MCT-induced liver injury remains controversial. In current work, we investigated the effects of KCs on MCT-induced liver injury, especially on MCT-induced hepatocyte death. KCs were depleted in Balb/c mice by liposome-entrapped clodronate (Lip/Clo) (0.2 mL/mouse, i.p.) or GdCl3 (0.7 mg/kg, i.p.) before MCT administration (300 mg/kg, i.p.), we found that the Lip/Clo group showed higher efficiency in KCs depletion and stronger hepatoprotective effects against MCT. We also found TNF-α was remarkably decreased after KCs depletion, the experiment of administering anti-TNF-α antibody (20 µg/mouse, i.p.) to MCT-treated animals generated the similar results. To further elaborate the function of KCs, we compared the ALT levels released from co-culturing murine hepatic parenchymal cells (HPCs) and RAW264.7 cells with that from HPCs alone. After the treatment of MCT, the released ALT levels in co-culture system were shown to be dependent on the number of RAW264.7 cells, while the anti-TNF-α antibody could suppress it. Finally, we discovered RIPK3/MLKL pathway might be activated by TNF-α released from KCs, and subsequently induced hepatocyte necrosis. Noteworthy, the known mechanisms including ER stress and NF-κB pathways were also found to be involved in the activation of KCs. In conclusion, our study reveals a further mechanism to MCT-induced hepatoxicity mediated directly by KCs via producing TNF-α.

A new recombinant MS-superoxide dismutase alleviates 5-fluorouracil-induced intestinal mucositis in mice.

Intestinal mucositis is a common side effect of anticancer regimens that exerts a negative impact on chemotherapy. Superoxide dismutase (SOD) is a potential therapy for mucositis but efficient product is not available because the enzyme is degraded following oral administration or induces an immune reaction after intravascular infusion. Multi-modified Stable Anti-Oxidant Enzymes® (MS-AOE®) is a new recombinant SOD with better resistance to pepsin and trypsin. We referred it as MS-SOD to distinguish from other SODs. In this study we investigated its potential to alleviate 5-FU-induced intestinal injury and the mechanisms. An intestinal mucositis model was established in C57/BL6 mice by 5-day administration of 5-FU (50 mg/kg every day, ip). MS-SOD (800 IU/10 g, ig) was given once daily for 9 days. 5-FU caused severe mucositis with intestinal morphological damage, bodyweight loss and diarrhea; MS-SOD significantly decreased the severity. 5-FU markedly increased reactive oxygen species (ROS) and inflammatory cytokines in the intestine which were ameliorated by MS-SOD. Furthermore, MS-SOD modified intestinal microbes, particularly reduced Verrucomicrobia, compared with the 5-FU group. In Caco2 cells, MS-SOD (250-1000 U/mL) dose-dependently decreased tBHP-induced ROS generation. In RAW264.7 cells, MS-SOD (500 U/mL) had no effect on LPS-induced inflammatory cytokines, but inhibited iNOS expression. These results demonstrate that MS-SOD can scavenge ROS at the initial stage of injury, thus play an indirect role in anti-inflammatory and barrier protein protection. In conclusion, MS-SOD attenuates 5-FU-induced intestinal mucositis by suppressing oxidative stress and inflammation, and influencing microbes. MS-SOD may exert beneficial effect in prevention of intestinal mucositis during chemotherapy in clinic.

Effects of fluoride and aluminum on expressions of StAR and P450scc of related steroidogenesis in guinea pigs' testis.

A lot of studies have shown that fluoride and aluminum have toxic effect on male reproductive system, but the mechanism of which and the interaction between fluoride and aluminum is still unknown. This study investigated the effects of fluoride (NaF) or/and aluminum (AlCl3) on serum testosterone level, gene and protein expression levels of Steroidogenic Acute Regulatory Protein (StAR) and Cytochrome P450 cholesterol side chain cleavage enzyme (P450scc) in the testes of guinea pigs. Fifty-two guinea pigs were divided randomly into four groups (Control, HiF, HiAl and HiF + HiAl). Fluoride (150 mg NaF/L) or/and aluminum (300 mg AlCl3/L) were orally administrated to male guinea pigs for 13 weeks. The results showed that F and Al reduced number and elevated abnormal ratio of sperm. Meanwhile, the concentrations of serum testosterone in all experimental groups were decreased. P450scc protein expression was significantly reduced in all treatment groups, and StAR expression was decreased remarkably in HiF group and HiF + HiAl group. The levels of StAR mRNA in three groups were reduced by 53.9%, 21.4% and 33.4%, respectively, while the expressions of P450scc mRNA were reduced by 67.8%, 17.0% and 47.8%. Therefore, we concluded that F induced the reduction in testosterone and sperm amount, and thus in lower fertility, which might occur as a consequence of depressed StAR and P450scc mRNA expression. There were no synergistic effects between F and Al, instead, Al weakened the toxicity of F to some extents. The results indicated that Al had antagonism effects on F.