Selenium suppresses lipopolysaccharide-induced fibrosis in peritoneal mesothelial cells through inhibition of epithelial-to-mesenchymal transition

Using the concept of food as medicine to mitigate inflammation in patients undergoing peritoneal dialysis

The most common kidney replacement therapy (KRT) worldwide is hemodialysis (HD), and only 5%-10% of patients are prescribed peritoneal dialysis (PD) as KRT. Despite PD being a different method, these patients also present particular complications, such as oxidative stress, gut dysbiosis, premature aging, and mitochondrial dysfunction, leading to an inflammation process and high cardiovascular mortality risk. Although recent studies have reported nutritional strategies in patients undergoing HD with attempts to mitigate these complications, more information must be needed for PD patients. Therefore, this review provides a comprehensive analysis of recent studies of nutritional intervention to mitigate inflammation in PD patients.

Application of natural polysaccharides and their novel dosage forms in gynecological cancers: therapeutic implications from the diversity potential of natural compounds

Cancer is one of the most lethal diseases. Globally, the number of cancers is nearly 10 million per year. Gynecological cancers (for instance, ovarian, cervical, and endometrial), relying on hidden diseases, misdiagnoses, and high recurrence rates, have seriously affected women's health. Traditional chemotherapy, hormone therapy, targeted therapy, and immunotherapy effectively improve the prognosis of gynecological cancer patients. However, with the emergence of adverse reactions and drug resistance, leading to the occurrence of complications and poor compliance of patients, we have to focus on the new treatment direction of gynecological cancers. Because of the potential effects of natural drugs in regulating immune function, protecting against oxidative damage, and improving the energy metabolism of the body, natural compounds represented by polysaccharides have also attracted extensive attention in recent years. More and more studies have shown that polysaccharides are effective in the treatment of various tumors and in reducing the burden of metastasis. In this review, we focus on the positive role of natural polysaccharides in the treatment of gynecologic cancer, the molecular mechanisms, and the available evidence, and discuss the potential use of new dosage forms derived from polysaccharides in gynecologic cancer. This study covers the most comprehensive discussion on applying natural polysaccharides and their novel preparations in gynecological cancers. By providing complete and valuable sources of information, we hope to promote more effective treatment solutions for clinical diagnosis and treatment of gynecological cancers.

Hepatoprotective Effects of a Natural Flavanol 3,3'-Diindolylmethane against CCl4-Induced Chronic Liver Injury in Mice and TGFβ1-Induced EMT in Mouse Hepatocytes via Activation of Nrf2 Cascade

Hepatic fibrosis is a form of irregular wound-healing response with acute and chronic injury triggered by the deposition of excessive extracellular matrix. Epithelial-mesenchymal transition (EMT) is a dynamic process that plays a crucial role in the fibrogenic response and pathogenesis of liver fibrosis. In the present study, we postulated a protective role of 3,3'-diindolylmethane (DIM) against TGF-β1 mediated epithelial-mesenchymal transition (EMT) in vitro and carbon tetrachloride (CCl4)-induced liver fibrosis in mice. TGF-β1-induced AML-12 hepatocyte injury was evaluated by monitoring cell morphology, measuring reactive oxygen species (ROS) and mitochondrial membrane potential, and quantifying apoptosis, inflammatory, and EMT-related proteins. Furthermore, CCl4-induced liver fibrosis in mice was evaluated by performing liver function tests, including serum ALT and AST, total bilirubin, and albumin to assess liver injury and by performing H&E and Sirius red staining to determine the degree of liver fibrosis. Immunoblotting was performed to determine the expression levels of inflammation, apoptosis, and Nrf2/HO-1 signaling-related proteins. DIM treatment significantly restored TGF-β1-induced morphological changes, inhibited the expression of mesenchymal markers by activating E-cadherin, decreased mitochondrial membrane potential, reduced ROS intensity, and upregulated levels of Nrf2-responsive antioxidant genes. In the mouse model of CCl4-induced liver fibrosis, DIM remarkably attenuated liver injury and liver fibrosis, as reflected by the reduced ALT and AST parameters with increased serum Alb activity and fewer lesions in H&E staining. It also mitigated the fibrosis area in Sirius red and Masson staining. Taken together, our results suggest a possible molecular mechanism of DIM by suppressing TGF-β1-induced EMT in mouse hepatocytes and CCl4-induced liver fibrosis in mice.

Melatonin prevents LPS-induced epithelial-mesenchymal transition in human alveolar epithelial cells via the GSK-3β/Nrf2 pathway

BACKGROUND

Oxidative stress plays a critical role in pulmonary fibrosis after acute lung injury (ALI), and epithelial-mesenchymal transition (EMT) events are involved in this process. The purpose of this study was to investigate the protective effects of melatonin, a natural antioxidant, on lipopolysaccharide (LPS)-induced EMT in human alveolar epithelial cells.

METHODS

Human type II alveolar epithelial cell-derived A549 cells were incubated with LPS and melatonin alone or in combination for up to 24 h. The morphological changes of the treated cells were evaluated as well as indexes of oxidative stress. EMT-related proteins and the Nrf2 signaling pathway were detected by western blot analysis and immunofluorescence staining, respectively. To further investigate the underlying mechanisms, the effects of melatonin on cells transfected Nrf2 short hairpin RNA (shRNA) and the PI3K / GSK-3β signaling pathway were evaluated.

RESULTS

Treatment with melatonin upregulated Nrf2 expression, inhibited LPS-induced cell morphological change, reversed the expressions of EMT-related proteins, and reduced reactive oxygen species (ROS) production in A549 cells, as well as the levels of malondialdehyde (MDA) and anti-oxidative enzymes. Yet, the effects of melatonin were almost completely abolished in cells transfected Nrf2 shRNA. Furthermore, the data demonstrated that melatonin could activate the PI3K/AKT signaling pathway, resulting in phosphorylation of GSK-3β (Ser9) and upregulation of the Nrf2 protein in A549 cells, which ultimately attenuated LPS-induced EMT.

CONCLUSION

The present study is the first to demonstrate that melatonin can protect human alveolar epithelial cells against oxidative stress by effectively inhibiting LPS-induced EMT, which was mostly dependent on upregulation of the Nrf2 pathway via the PI3K/GSK-3β axis. Further studies are warranted to investigate the role of melatonin for the treatment of oxidative stress-associated diseases, as well as pulmonary fibrosis after ALI.

Loosening of the mesothelial barrier as an early therapeutic target to preserve peritoneal function in peritoneal dialysis

Phenotype transition of peritoneal mesothelial cells (MCs) including the epithelial-to-mesenchymal transition (EMT) is regarded as an early mechanism of peritoneal dysfunction and fibrosis in peritoneal dialysis (PD), producing proinflammatory and pro-fibrotic milieu in the intra-peritoneal cavity. Loosening of intercellular tight adhesion between adjacent MCs as an initial process of EMT creates the environment where mesothelium and submesothelial tissue are more vulnerable to the composition of bio-incompatible dialysates, reactive oxygen species, and inflammatory cytokines. In addition, down-regulation of epithelial cell markers such as E-cadherin facilitates de novo acquisition of mesenchymal phenotypes in MCs and production of extracellular matrices. Major mechanisms underlying the EMT of MCs include induction of oxidative stress, pro-inflammatory cytokines, endoplasmic reticulum stress and activation of the local renin-angiotensin system. Another mechanism of peritoneal EMT is mitigation of intrinsic defense mechanisms such as the peritoneal antioxidant system and anti-fibrotic peptide production in the peritoneal cavity. In addition to use of less bio-incompatible dialysates and optimum treatment of peritonitis in PD, therapies to prevent or alleviate peritoneal EMT have demonstrated a favorable effect on peritoneal function and structure, suggesting that EMT can be an early interventional target to preserve peritoneal integrity.

Sodium Propionate Attenuates the Lipopolysaccharide-Induced Epithelial-Mesenchymal Transition via the PI3K/Akt/mTOR Signaling Pathway

Short-chain fatty acids (SCFAs), especially propionate, originate from the fermentation of dietary fiber in the gut and play a key role in inhibiting pulmonary inflammation. Chronic inflammation may induce an epithelial-mesenchymal transition (EMT) in alveolar epithelial cells and result in fibrotic disorders. This study was designed to investigate the beneficial effect of sodium propionate (SP) on lipopolysaccharide (LPS)-induced EMT. In cultured BEAS-2B cells, the protein expression levels of E-cadherin, α-smooth muscle actin (SMA), and vimentin were 0.66 ± 0.20, 1.44 ± 0.23, and 1.32 ± 0.21 in the LPS group vs 1.11 ± 0.36 (P < 0.05), 1.04 ± 0.30 (P < 0.05), and 0.96 ± 0.13 (P < 0.01) in the LPS + SP group (mean ± standard deviation), respectively. Meanwhile, LPS-triggered inflammatory cytokines and extracellular proteins were also reduced by SP administration in BEAS-2B cells. Moreover, SP treatment attenuated inflammation, EMT, extracellular matrix (ECM) deposition, and even fibrosis in a mouse EMT model. In terms of mechanism, LPS-treated BEAS-2B cells exhibited a higher level of phosphatidylinositol 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) phosphorylation, which was interrupted by SP treatment. It is worth noting that the blockade of the PI3K/Akt/mTOR signaling cascade reduced the LPS-evoked EMT process in BEAS-2B cells. These results suggest that SP can block LPS-induced EMT via inhibition of the PI3K/Akt/mTOR signaling cascade, which provides a basis for possible clinical use of SP in airway and lung diseases.

Molecular hydrogen regulates PTEN-AKT-mTOR signaling via ROS to alleviate peritoneal dialysis-related peritoneal fibrosis

As a convenient, effective and economical kidney replacement therapy for end-stage renal disease (ESRD), peritoneal dialysis is available in approximately 11% of ESRD patients worldwide. However, long-term peritoneal dialysis treatment causes peritoneal fibrosis. In recent years, the application potential of molecular hydrogen in the biomedicine has been well recognized. Molecular hydrogen selectively scavenges cytotoxic reactive oxygen species (ROS) and acts as an antioxidant. In this experiment, a high glucose-induced peritoneal fibrosis mouse model was successfully established by intraperitoneal injection of high glucose peritoneal dialysate, and peritoneal fibrosis mice were treated with hydrogen-rich peritoneal dialysate. In addition, in vitro studies of high glucose-induced peritoneal fibrosis were performed using MeT-5A cells. In vitro and in vivo experiments show that molecular hydrogen could inhibit peritoneal fibrosis progress induced by high glucose effectively. Furthermore, it has been found that molecular hydrogen alleviate fibrosis by eliminating intracellular ROS and inhibiting the activation of the PTEN/AKT/mTOR pathway. The present data proposes that molecular hydrogen exerts the capacity of anti-peritoneal fibrosis through the ROS/PTEN/AKT/mTOR pathway. Therefore, molecule hydrogen is a potential, safe, and effective treatment agent, with peritoneal protective property and great clinical significance.

Nitro-oleic acid inhibits the high glucose-induced epithelial-mesenchymal transition in peritoneal mesothelial cells and attenuates peritoneal fibrosis

As an electrophilic nitroalkene fatty acid, nitro-oleic acid (OA-NO₂) exerts multiple biological effects that contribute to anti-inflammation, anti-oxidative stress, and antiapoptosis. However, little is known about the role of OA-NO₂ in peritoneal fibrosis. Thus, in the present study, we examined the effects of OA-NO₂ on the high glucose (HG)-induced epithelial-mesenchymal transition (EMT) in human peritoneal mesothelial cells (HPMCs) and evaluated the morphological and immunohistochemical changes in a rat model of peritoneal dialysis-related peritoneal fibrosis. In in vitro experiments, we found that HG reduced the expression level of E-cadherin and increased Snail, N-cadherin, and α-smooth muscle actin expression levels in HPMCs. The above-mentioned changes were attenuated by pretreatment with OA-NO₂. Additionally, OA-NO₂ also inhibited HG-induced activation of the transforming growth factor-β₁/Smad signaling pathway and NF-κB signaling pathway. Meanwhile, OA-NO₂ inhibited HG-induced phosphorylation of Erk and JNK. The results from the in vivo experiments showed that OA-NO₂ notably relieved peritoneal fibrosis by decreasing the thickness of the peritoneum; it also inhibited expression of transforming growth factor-β₁, α-smooth muscle actin, N-cadherin, and vimentin and enhanced expression of E-cadherin in the peritoneum. Collectively, these results suggest that OA-NO₂ inhibits the HG-induced epithelial-mesenchymal transition in HPMCs and attenuates peritoneal dialysis-related peritoneal fibrosis.

The Role of Cathepsin B in Peritoneal Fibrosis due to Peritoneal Dialysis

Glucose-containing peritoneal dialysis (PD) solution causes peritoneal fibrosis (PF) characterized by accumulation of extracellular matrix (ECM) in the submesothelial layer. Cathepsin B is a lysosomal cysteine protease that degrades ECM, but its role in the PF remains unclear. Thus, we investigated the role of cathepsin B in PF. Procathepsin B was measured in the 73 PD effluents of 68 patients. Procathepsin B and cathepsin B after exposure of glucose and the effects of cathepsin B on the expression of matrix metalloproteinases (MMPs), tissue inhibitor of metalloproteinases (TIMPs), and urokinase-type plasminogen activator (uPA) were measured in the supernatant of cultured human peritoneal mesothelial cells (HPMCs). The effect of cathepsin B and its inhibitor, cystatin C, on PF was investigated in the murine model. Procathepsin B was measured at 3.6 μg/L in serum and 5.4 μg/L in PD effluent and positively correlated to the cancer antigen (CA) 125. The treatment with 4.25% glucose increased procathepsin B by 3.1-fold and cathepsin B by 5.9-fold in the HPMCs. Cathepsin B induced the secretion of MMP-1, -2, and -3 and TIMP-1 in the HPMCs, but uPA was not excreted. In the PF murine models, cathepsin B reduced the thickness of the submesothelial layer and cystatin C attenuated the effect of cathepsin B. HPMCs secrete cathepsin B with exposure of PD solution, and cathepsin B might help protect against PF.

Effect of astragaloside IV and the role of nuclear receptor RXRα in human peritoneal mesothelial cells in high glucose‑based peritoneal dialysis fluids

Peritoneal fibrosis is a serious complication that can occur during peritoneal dialysis (PD), which is primarily caused by damage to peritoneal mesothelial cells (PMCs). The onset of peritoneal fibrosis is delayed or inhibited by promoting PMC survival and inhibiting PMC epithelial-to-mesenchymal transition (EMT). In the present study, the effect of astragaloside IV and the role of the nuclear receptor retinoid X receptor-α (RXRα) in PMCs in high glucose-based PD fluids was investigated. Human PMC HMrSV5 cells were transfected with RXRα short hairpin RNA (shRNA), or an empty vector, and then treated with PD fluids and astragaloside IV. Cell viability, apoptosis and EMT were examined using the Cell Counting Kit-8 assay and flow cytometry, and by determining the levels of caspase-3, E-cadherin and α-smooth muscle actin (α-SMA) via western blot analysis. Cell viability and apoptosis were increased, as were the levels of E-cadherin in HMrSV5 cells following treatment with PD fluid. The protein levels of α-SMA and caspase-3 were increased by treatment with PD fluid. Exposure to astragaloside IV inhibited these changes; however, astragaloside IV did not change cell viability, apoptosis, E-cadherin or α-SMA levels in HMrSV5 cells under normal conditions. Transfection of HMrSV5 cells with RXRα shRNA resulted in decreased viability and E-cadherin expression, and increased apoptosis and α-SMA levels, in HMrSV5 cells treated with PD fluids and co-treated with astragaloside IV or vehicle. These results suggested that astragaloside IV increased cell viability, and inhibited apoptosis and EMT in PMCs in PD fluids, but did not affect these properties of PMCs under normal condition. Thus, the present study suggested that RXRα is involved in maintaining viability, inhibiting apoptosis and reducing EMT of PMCs in PD fluid.

Matrine suppresses lipopolysaccharide-induced fibrosis in human peritoneal mesothelial cells by inhibiting the epithelial-mesenchymal transition

Background:

Peritoneal fibrosis is the primary reason that patients with end-stage renal disease (ESRD) have to cease peritoneal dialysis. Peritonitis caused by Gram-negative bacteria such as Escherichia coli (E. coli) were on the rise. We had previously shown that matrine inhibited the formation of biofilm by E. coli. However, the role of matrine on the epithelial-mesenchymal transition (EMT) in peritoneal mesothelial cells under chronic inflammatory conditions is still unknown.

Methods:

We cultured human peritoneal mesothelial cells (HPMCs) with lipopolysaccharide (LPS) to induce an environment that mimicked peritonitis and investigated whether matrine could inhibit LPS-induced EMT in these cells. In addition, we investigated the change in expression levels of the miR-29b and miR-129-5p.

Results:

We found that 10 μg/ml of LPS induced EMT in HPMCs. Matrine inhibited LPS-induced EMT in HPMCs in a dose-dependent manner. We observed that treatment with matrine increased the expression of E-cadherin (F = 50.993, P < 0.01), and decreased the expression of alpha-smooth muscle actin (F = 32.913, P < 0.01). Furthermore, we found that LPS reduced the expression levels of miR-29b and miR-129-5P in HPMCs, while matrine promoted the expression levels of miR-29b and miR-129-5P.

Conclusions:

Matrine could inhibit LPS-induced EMT in HPMCs and reverse LPS inhibited expressions of miR-29 b and miR-129-5P in HPMCs, ultimately reduce peritoneal fibrosis. These findings provide a potential theoretical basis for using matrine in the prevention and treatment of peritoneal fibrosis.

Zinc supplementation inhibits the high glucose‑induced EMT of peritoneal mesothelial cells by activating the Nrf2 antioxidant pathway

The high glucose (HG)-induced epithelial-mesenchymal transition (EMT) of peritoneal mesothelial cells (PMCs) serves an important role in peritoneal fibrosis (PF) during peritoneal dialysis. Our previous study reported that zinc (Zn) supplementation prevented the HG-induced EMT of rat PMCs in vitro. In the present study, the role of Zn in HG-induced EMT was investigated in vivo using a rat model of PF. Additionally, the molecular mechanisms underlying HG-induced EMT were studied in human PMCs (HPMCs). In the rat model of PF, HG treatment increased the glucose transfer capacity and decreased the ultrafiltration volume. Histopathological analysis revealed peritoneal thickening, increased expression of vimentin and decreased expression of E-cadherin. ZnSO₄ significantly ameliorated the aforementioned changes, whereas Zn inhibition by clioquinol significantly aggravated the effects of HG on rats. The effects of Zn on HPMCs was assessed using western blot analysis, Transwell assays and flow cytometry. It was revealed that Zn also significantly suppressed the extent of the EMT, and reduced reactive oxygen species production and the migratory ability of HG-induced HPMCs, whereas Zn inhibition by N',N',N',N'-tetrakis (2-pyridylmethyl) ethylenediamine significantly potentiated the HG-induced EMT of HPMCs. HG-stimulated HPMCs exhibited increased expression of nuclear factor-like 2 (Nrf2) in the nucleus, and total cellular NAD(P)H quinone dehydrogenase 1 (NQO1) and heme oxygenase-1 (HO-1), the target proteins of the Nrf2 antioxidant pathway. Zn supplementation further promoted nuclear Nrf2 expression, and increased the expression of target proteins of the Nrf2 antioxidant pathway, whereas Zn depletion decreased nuclear Nrf2, NQO1 and HO-1 expression compared with the HG group. In conclusion, Zn supplementation was proposed to suppress the effects of HG on the EMT by stimulating the Nrf2 antioxidant pathway and subsequently reducing oxidative stress in PMCs.

Network-based integrated analysis of omics data reveal novel players of TGF-β1-induced EMT in human peritoneal mesothelial cells

Long-term peritoneal dialysis is associated with progressive fibrosis of the peritoneum. Epithelial-mesenchymal transition (EMT) of mesothelial cells is an important mechanism involved in peritoneal fibrosis, and TGF-β1 is considered central in this process. However, targeting currently known TGF-β1-associated pathways has not proven effective to date. Therefore, there are still gaps in understanding the mechanisms underlying TGF-β1-associated EMT and peritoneal fibrosis. We conducted network-based integrated analysis of transcriptomic and proteomic data to systemically characterize the molecular signature of TGF-β1-stimulated human peritoneal mesothelial cells (HPMCs). To increase the power of the data, multiple expression datasets of TGF-β1-stimulated human cells were employed, and extended based on a human functional gene network. Dense network sub-modules enriched with differentially expressed genes by TGF-β1 stimulation were prioritized and genes of interest were selected for functional analysis in HPMCs. Through integrated analysis, ECM constituents and oxidative stress-related genes were shown to be the top-ranked genes as expected. Among top-ranked sub-modules, TNFAIP6, ZC3H12A, and NNT were validated in HPMCs to be involved in regulation of E-cadherin, ZO-1, fibronectin, and αSMA expression. The present data shows the validity of network-based integrated analysis in discovery of novel players in TGF-β1-induced EMT in peritoneal mesothelial cells, which may serve as new prognostic markers and therapeutic targets for peritoneal dialysis patients.

Baicalin and puerarin reverse epithelial-mesenchymal transition via the TGF-β1/Smad3 pathway in vitro

Epithelial-mesenchymal transition (EMT) occurs in the development of fibrosis and carcinogenesis. EMT is associated with chronic liver injury. Evidence shows that hepatocytes undergo EMT in the adult liver. The Qinggan Huoxue Recipe (QGHXR), a Traditional Chinese Medicinal formula, shows a range of pharmacological effects in treating alcoholic liver disease. The present study aimed to investigate the effect of four major components of QGHXR, baicalin, salvianic acid, puerarin and saikosaponin, on EMT in vitro, and to elucidate the potential mechanism of QGHXR against EMT via the transforming growth factor-β1 (TGF-β1)/Smads signaling pathway. EMT models were established using LO2 hepatocytes and HepG2 cells treated with acetaldehyde in vitro. Acetaldehyde presented a mesenchymal cell characteristic in hepatocytes, accompanied by an increased expression of mesenchymal markers, including vimentin and fibronectin, and decreased E-cadherin. Baicalin and puerarin abrogated the increased expression of vimentin and fibronectin, and rescued E-cadherin expression in acetaldehyde-treated hepatocytes. It was further demonstrated that baicalin and puerarin reduced the gene expression of snail, TGF-β1 and Smad3. A decreased expression of tight function markers, including ZO-1, occludin and claudin, were also found in the acetaldehyde-treated hepatocytes. Barcacin regulated the mRNA level of TGF-βl and snail, and then suppressed the EMT process. This was accompanied by an increased mRNA level of E-cadherin and decreased levels of vimentin and fibronectin, but no significant differences in of Smad3, occludin, ZO-1 and claudin were observed. Puerarin regulated the mRNA level of TGF-βl, Smad3 and snail, suppresing the EMT process, which was accompanied by an increased mRNA level of E-cadherin and decreased levels of vimentin and fibronectin, along with increased levels of occludin, ZO-1 and claudin. When the snail gene was silent, barcacin and puerarin did not show significant effects in the acetaldehyde-treated cells. The results presented a novel mechanism through which baicalin and puerarin modulated hepatocyte EMT to improve liver fibrosis.

Selenium-enriched polysaccharides from Pyracantha fortuneana (Se-PFPs) inhibit the growth and invasive potential of ovarian cancer cells through inhibiting β-catenin signaling

Polysaccharides from medicinal plants exert antitumor activity in many cancers. Our previous study demonstrated that polysaccharides extracted from the selenium-enriched Pyracantha fortuneana (Se-PFPs) showed antiproliferative effect in breast cancer cell line. This study aimed to investigate the antitumor effect of Se-PFPs in ovarian cancer cells in vitro and in vivo. Se-PFPs could decrease cell viability, induce apoptosis, and inhibit migratory and invasive potentials in HEY and SKOV3 cells. These findings are supported by reduced expression of cyclin D1, Bcl-2 and MMP-9, enhanced cleavage of PARP and caspase-3, elevated activity of caspase-3 and caspase-9, and EMT (epithelial to mesenchymal transition) inhibition (elevated expression of E-cadherin and cytokeratin 19, and reduced expression of N-cadherin, vimentin, ZEB1 and ZEB2). Moreover, Se-PFPs inhibited xenografted tumor growth through inhibiting cell proliferation and inducing cell apoptosis. More importantly, Se-PFPs significantly reduced cytoplasmic β-catenin particularly nuclear β-catenin expression but increased β-catenin phosphorylation in a GSK-3β-dependent mechanism. Furthermore, β-catenin knockdown exerted similar effects on cell proliferation and invasion as seen in Se-PFPs-treated cells, while β-catenin overexpression neutralized the inhibitory effects of Se-PFPs on cell proliferation and invasion. Take together,Se-PFPs exert antitumor activity through inhibiting cell proliferation, migration, invasion and EMT, and inducing cell apoptosis. These effects are achieved by the inhibition of β-catenin signaling. Thus Se-PFPs can be used as potential therapeutic agents in the prevention and treatment of ovarian cancer.

Selenium protects against cadmium-induced kidney apoptosis in chickens by activating the PI3K/AKT/Bcl-2 signaling pathway

Cadmium (Cd) is a toxic heavy metal that can induce apoptosis. Selenium (Se) is a necessary trace element and can antagonize the toxicity of many heavy metals, including Cd. PI3K/AKT/Bcl-2 is a key survival signaling pathway that regulates cellular defense system against oxidative injury as well as cell proliferation, survival, and apoptosis. The antagonistic effects of Se on Cd-induced toxicity have been reported. However, little is known about the effect of Se on Cd-induced apoptosis in chicken kidneys via the PI3K/AKT/Bcl-2 signaling pathway. In the present study, we fed chickens with Se, Cd, or both Se and Cd supplements, and after 90 days of treatment, we detected the related index. The results showed that the activity of inducible nitric oxide synthase (iNOS) and concentration of nitric oxide (NO) were increased; activities of the mitochondrial respiratory chain complexes (complexes I, II, and V) and ATPases (the Na⁺-K⁺-ATPase, the Mg²⁺-ATPase, and the Ca²⁺-ATPase) were decreased; expression of PI3K, AKT, and Bcl-2 were decreased; and expression of Bax, Bak, P53, Caspase-3, Caspase-9, and cytochrome c (Cyt c) were increased. Additionally, the results of the TUNEL assay showed that the number of apoptotic cells was increased in the Cd group. By contrast, there was a significant improvement of the correlation indicators and occurrence of apoptosis in the Se + Cd group compared to the Cd group. In conclusion, our results confirmed that Se had a positive effect on ameliorating Cd-induced apoptosis in chicken kidney tissue by activating the PI3K/AKT/Bcl-2 signaling pathway.

IL-6 promotes epithelial-to-mesenchymal transition of human peritoneal mesothelial cells possibly through the JAK2/STAT3 signaling pathway

Long-term peritoneal dialysis (PD) therapy results in functional and structural alteration of the peritoneal membrane, including epithelial-to-mesenchymal transition (EMT). Interleukin 6 (IL-6) is a local pleiotropic cytokine, hypothesized to play an important role in EMT. This study was designed to investigate the role of IL-6 in EMT and peritoneal membrane dysfunction in long-term PD patients by assessing the level of IL-6 in dialysate and exploring the relationship between IL-6, the related signaling pathway JAK2/STAT3, and EMT, using in vitro cellular and molecular techniques. Plasma and dialysate levels of IL-6 were significantly higher in PD ultrafiltration failure patients compared with patients without ultrafiltration failure and were negatively correlated with measures of PD adequacy. In vitro IL-6 treatment changed human peritoneal mesothelial cell phenotype from a typical cobblestone-like to a fibroblast-like appearance and increased cell viability. IL-6 treatment increased α-smooth muscle actin and vascular endothelial growth factor expression but decreased E-cadherin expression. IL-6 treatment activated the JAK/STAT signaling pathway. However, the JAK2/STAT3 inhibitor WP1066 prevented IL-6-induced activation of the JAK2/STAT3 pathway and EMT. We conclude that IL-6 promotes the EMT process, possibly by activating the JAK2/STAT3 signaling pathway. IL-6 may serve as a novel therapeutic target for preventing EMT, and preservation of the peritoneal membrane may arise from these studies.

Targeting cannabinoid signaling for peritoneal dialysis-induced oxidative stress and fibrosis

Long-term exposure to bioincompatible peritoneal dialysis (PD) solutions frequently results in peritoneal fibrosis and ultrafiltration failure, which limits the life-long use of and leads to the cessation of PD therapy. Therefore, it is important to elucidate the pathogenesis of peritoneal fibrosis in order to design therapeutic strategies to prevent its occurrence. Peritoneal fibrosis is associated with a chronic inflammatory status as well as an elevated oxidative stress (OS) status. Beyond uremia per se, OS also results from chronic exposure to high glucose load, glucose degradation products, advanced glycation end products, and hypertonic stress. Therapy targeting the cannabinoid (CB) signaling pathway has been reported in several chronic inflammatory diseases with elevated OS. We recently reported that the intra-peritoneal administration of CB receptor ligands, including CB₁ receptor antagonists and CB₂ receptor agonists, ameliorated dialysis-related peritoneal fibrosis. As targeting the CB signaling pathway has been reported to be beneficial in attenuating the processes of several chronic inflammatory diseases, we reviewed the interaction among the cannabinoid system, inflammation, and OS, through which clinicians ultimately aim to prolong the peritoneal survival of PD patients.

1,25(OH)2D3/VDR attenuates high glucose‑induced epithelial‑mesenchymal transition in human peritoneal mesothelial cells via the TGFβ/Smad3 pathway

Epithelial-mesenchymal transition (EMT) has been recognized to accelerate peritoneal membrane dysfunction. 1,25(OH)2D3/vitamin D receptor (VDR) is important for preventing various types of EMT in vivo. However, its function on EMT and inflammation of human peritoneal mesothelial cells (HPMCs) remains to be elucidated. Therefore, the present study investigated the effects of 1,25(OH)2D3/VDR on high glucose (HG)‑induced EMT and inflammation in HPMCs and the underlying molecular mechanism. It was determined that HG reduced VDR expression, increased inflammatory cytokine expression, including transforming growth factor β (TGFβ) and interleukin‑6 (IL‑6) and phosphorylated‑SMAD family member 3 (p‑Smad3) expression. EMT was promoted as the expression level of the epithelial marker E‑cadherin was reduced, whereas expression levels of the mesenchymal markers α‑SMA and FN were increased. 1,25(OH)2D3 pretreatment inhibited the expression of inflammatory cytokines in HPMCs and attenuated HG‑induced EMT, possibly through inhibition of the TGFβ/Smad pathway by binding to its receptor VDR.

Preventing peritoneal membrane fibrosis in peritoneal dialysis patients

Long-term peritoneal dialysis causes morphologic and functional changes in the peritoneal membrane. Although mesothelial-mesenchymal transition of peritoneal mesothelial cells is a key process leading to peritoneal fibrosis, and bioincompatible peritoneal dialysis solutions (glucose, glucose degradation products, and advanced glycation end products or a combination) are responsible for altering mesothelial cell function and proliferation, mechanisms underlying these processes remain largely unclear. Peritoneal fibrosis has 2 cooperative parts, the fibrosis process itself and the inflammation. The link between these 2 processes is frequently bidirectional, with each one inducing the other. This review outlines our current understanding about the definition and pathophysiology of peritoneal fibrosis, recent studies on key fibrogenic molecular machinery in peritoneal fibrosis, such as the role of transforming growth factor-β/Smads, transforming growth factor-β β/Smad independent pathways, and noncoding RNAs. The diagnosis of peritoneal fibrosis, including effluent biomarkers and the histopathology of a peritoneal biopsy, which is the gold standard for demonstrating peritoneal fibrosis, is introduced in detail. Several interventions for peritoneal fibrosis based on biomarkers, cytology, histology, functional studies, and antagonists are presented in this review. Recent experimental trials in animal models, including pharmacology and gene therapy, which could offer novel insights into the treatment of peritoneal fibrosis in the near future, are also discussed in depth.

Qinggan Huoxue Recipe suppresses epithelial-to-mesenchymal transition in alcoholic liver fibrosis through TGF-β1/Smad signaling pathway

AIM: To investigate the mechanism by which Qinggan Huoxue Recipe (QGHXR) inhibits epithelial-to-mesenchymal transition (EMT) in rats with alcoholic liver fibrosis (ALF).

METHODS: A total of 75 male SD rats were used to induce ALF. Serum biochemical indicators, including alanine aminotransferase, aspartate aminotransferase, laminin and hyaluronidase, were measured. Liver histopathological changes were evaluated using hematoxylin-eosin and Sirius red staining. EMT was examined by analyzing the expression of the epithelial marker E-cadherin and the mesenchymal markers vimentin and fibronectin using RT-PCR and Western blot. The inhibitory effect of QGHXR on EMT markers, as well as its effect on molecules associated with the transforming growth factor (TGF)-β1/Smad signaling pathway, including TGF-β1, Smad3, snail, occludin, ZO-1 and claudin, was also examined.

RESULTS: Compared with normal control rats, ALF rats exhibited a decrease in E-cadherin levels (mRNA: ALF 0.16 ± 0.05 vs control 1.00 ± 0.08; protein: ALF 0.09 ± 0.05 vs control 0.70 ± 0.17, P < 0.01) and an increase in vimentin and fibronectin levels (mRNA: 11.43 ± 0.39 vs 1.00 ± 0.19 and 9.91 ± 0.34 vs 1.00 ± 0.44, respectively, P < 0.01; protein: 1.13 ± 0.42 vs 0.09 ± 0.03 and 1.16 ± 0.43 vs 0.09 ± 0.00, respectively, P < 0.01). This indicates that EMT occurred in ALF rats. In addition, the TGF-β1/Smad signaling pathway was activated in ALF rats, as evidenced by the increase in TGF-β1 and snail levels (mRNA: 1.76 ± 0.12 vs 1.00 ± 0.05 and 6.98 ± 0.41 vs 1.00 ± 0.10, respectively, P < 0.01; protein: 1.43 ± 0.05 vs 0.12 ± 0.03 and 1.07 ± 0.29 vs 0.07 ± 0.02, respectively, P < 0.01) and the decrease in Smad3 levels (mRNA: 0.05 ± 0.01 vs 1.00 ± 0.12, P < 0.01; protein: 0.06 ± 0.05 vs 0.89 ± 0.12, P < 0.01). Furthermore, levels of the tight junction markers occludin, ZO-1 and claudin decreased in ALF rats compared with healthy control rats (mRNA: 0.60 ± 0.09 vs 1.00 ± 0.12, 0.11 ± 0.00 vs 1.00 ± 0.12 and 0.60 ± 0.01 vs 1.00 ± 0.08, respectively, P < 0.01; protein: 0.05 ± 0.01 vs 0.87 ± 0.40, 0.09 ± 0.05 vs 0.89 ± 0.18 and 0.04 ± 0.03 vs 0.95 ± 0.21, respectively, P < 0.01). In ALF rats treated with QGHXR, E-cadherin levels increased (mRNA: QGHXR 0.67 ± 0.04 vs ALF model 0.16 ± 0.05, P < 0.01; protein: QGHXR 0.66 ± 0.21 vs ALF model 0.09 ± 0.05, P < 0.01), and vimentin and fibronectin levels decreased (mRNA: 6.57 ± 1.05 vs 11.43 ± 0.39 and 1.45 ± 1.51 vs 9.91 ± 0.34, respectively, P < 0.01; protein: 0.09 ± 0.03 vs 1.13 ± 0.42 and 0.10 ± 0.01 vs 1.16 ± 0.43, respectively, P < 0.01). In addition, QGHXR inhibited the expression of TGF-β1 and increased the expression of Smad3 (mRNA: 1.03 ± 0.11 vs 1.76 ± 0.12, 0.70 ± 0.10 vs 0.05 ± 0.01, respectively, P < 0.05 and P < 0.01; protein: 0.12 ± 0.03 vs 1.43 ± 0.05 and 0.88 ± 0.20 vs 0.06 ± 0.05, respectively, P < 0.01). QGHXR treatment also reduced the levels of the EMT-inducing transcription factor snail (mRNA: 2.28 ± 0.33 vs 6.98 ± 0.41, P < 0.01; protein: 0.08 ± 0.02 vs 1.07 ± 0.29, P < 0.01) and increased the occludin, ZO-1 and claudin levels (mRNA: 0.73 ± 0.05 vs 0.60 ± 0.09, 0.57 ± 0.04 vs 0.11 ± 0.00 and 0.68 ± 0.03 vs 0.60 ± 0.01, respectively, P < 0.01, P < 0.01 and P < 0.05; protein: 0.92 ± 0.50 vs 0.05 ± 0.01, 0.94 ± 0.22 vs 0.09 ± 0.05 and 0.94 ± 0.29 vs 0.04 ± 0.03, respectively, P < 0.01). The effects of QGR and HXR on the TGF-β1/Smad signaling pathway were similar to that of QGHXR; however, the QGR- and HXR-induced changes in vimentin mRNA levels, the QGR-induced changes in fibronectin mRNA levels and the HXR-induced changes in snail and TGF-β1 mRNA levels were not significant.

CONCLUSION: Qinggan Huoxue Recipe inhibits EMT in ALF rats by modulating the TGF-β1/Smad signaling pathway, suggesting that the mechanism underlying the amelioration of ALF induced by QGHXR is associated with this pathway.

Rapamycin inhibits epithelial-to-mesenchymal transition of peritoneal mesothelium cells through regulation of Rho GTPases

Epithelial-mesenchymal transition (EMT) of peritoneal mesothelial cells (PMCs) is a key process of peritoneal fibrosis. Rapamycin has been previously shown to inhibit EMT of PMCs and prevent peritoneal fibrosis. In this study, we investigated the undefined molecular mechanisms by which rapamycin inhibits EMT of PMCs. To define the protective effect of rapamycin, we initially used a rat PD model which was daily infused with 20 mL of 4.25% high glucose (HG) dialysis solution for 6 weeks to induce fibrosis. The HG rats showed decreased ultrafiltration volume and obvious fibroproliferative response, with markedly increased peritoneal thickness and higher expression of α-smooth muscle actin (α-SMA) and transforming growth factor-β1. Rapamycin significantly ameliorated those pathological changes. Next, we treated rat PMCs with HG to induce EMT and/or rapamycin for indicated time. Rapamycin significantly inhibited HG-induced EMT, which manifests as increased expression of α-SMA, fibronectin, and collagen I, decreased expression of E-cadherin, and increased mobility. HG increased the phosphorylation of PI3K, Akt, and mTOR. Importantly, rapamycin inhibits the RhoA, Rac1, and Cdc42 activated by HG. Moreover, rapamycin repaired the pattern of F-actin distribution induced by HG, reducing the formation of stress fiber, focal adhesion, lamellipodia, and filopodia. Thus, rapamycin shows an obvious protective effect on HG-induced EMT, by inhibiting the activation of Rho GTPases (RhoA, Rac1, and Cdc42).

Effect of Ligustrazine on rat peritoneal mesothelial cells treated with lipopolysaccharide

The apoptosis of peritoneal mesothelial cells (PMCs) and peritoneal fibrosis may induce failure of peritoneal membrane function. The study explored the changes of apoptosis and fibrosis in PMCs under lipopolysaccharides (LPS) culture and investigated whether Ligustrazine can affect LPS-induced apoptosis and fibrosis. We found that exposure of rat PMCs to 5 mg·L(-1) LPS for 24 h resulted in a significant induction of apoptosis and increased levels in Reactive oxygen species, and caspase-3 activity. Fibronectin, Collagen I, p-p38, and matrix metalloprotein-9 (MMP-9) levels were also significantly increased by LPS. But superoxide dismutase levels were remarkably decreased. Ligustrazine can restore the changes induced by LPS. The protective effect of Ligustrazine on LPS-induced apoptosis and fibrosis may act through inhibition of oxidative stress and p38/MAPKS, ROS/MMP-9 activation in PMCs.

Mesothelial cells in tissue repair and fibrosis

Mesothelial cells are fundamental to the maintenance of serosal integrity and homeostasis and play a critical role in normal serosal repair following injury. However, when normal repair mechanisms breakdown, mesothelial cells take on a profibrotic role, secreting inflammatory, and profibrotic mediators, differentiating and migrating into the injured tissues where they contribute to fibrogenesis. The development of new molecular and cell tracking techniques has made it possible to examine the origin of fibrotic cells within damaged tissues and to elucidate the roles they play in inflammation and fibrosis. In addition to secreting proinflammatory mediators and contributing to both coagulation and fibrinolysis, mesothelial cells undergo mesothelial-to-mesenchymal transition, a process analogous to epithelial-to-mesenchymal transition, and become fibrogenic cells. Fibrogenic mesothelial cells have now been identified in tissues where they have not previously been thought to occur, such as within the parenchyma of the fibrotic lung. These findings show a direct role for mesothelial cells in fibrogenesis and open therapeutic strategies to prevent or reverse the fibrotic process.