Inhibition of autophagy induced by tetrandrine promotes the accumulation of reactive oxygen species and sensitizes efficacy of tetrandrine in pancreatic cancer.

Pancreatic cancer, characterized by its poor prognosis, exhibits a marked resistance to conventional chemotherapy and immunotherapy, underscoring the urgent need for more effective treatment modalities. In light of this, the present study is designed to assess the potential antineoplastic efficacy of a combined regimen involving tetrandrine, a plant-derived alkaloid, and autophagy inhibitors in the context of pancreatic cancer. Electron microscopy and immunoblots showed that tetrandrine promoted the formation of autophagosomes and the upregulation of LC3II and the downregulation of p62 expression, indicating that tetrandrine induced autophagy in pancreatic cancer cells. Western blot revealed that tetrandrine inhibited the phosphorylation of AKT and mTOR, as well as the expression of Bcl-2, while upregulating Beclin-1 expression. Moreover, tetrandrine promoted the transcription and protein expression of ATG7. Following the combination of autophagy inhibitors and tetrandrine, the apoptotic rate and cell death significantly increased in pancreatic cancer cells. Consistent results were obtained when ATG7 was silenced. Additionally, tetrandrine induced the generation of ROS, which was involved in the activation of autophagy and apoptosis. Further investigation revealed that upon autophagy inhibition, ROS accumulated in pancreatic cancer cells, resulting in decreased mitochondrial membrane potential and further induction of apoptosis. The results of treating subcutaneous xenograft tumors with a combination of tetrandrine and chloroquine validated that autophagy inhibition enhances the toxicity of tetrandrine against pancreatic cancer in vivo. Altogether, our study demonstrates that tetrandrine induces cytoprotective autophagy in pancreatic cancer cells. Inhibiting tetrandrine-induced autophagy promotes the accumulation of ROS and enhances its toxicity against pancreatic cancer.

Tetrandrine activates STING/TBK1/IRF3 pathway to potentiate anti-PD-1 immunotherapy efficacy in non-small cell lung cancer.

The efficacy of PD-1 therapy in non-small cell lung cancer (NSCLC) patients remains unsatisfactory. Activating the STING pathway is a promising strategy to improve PD-1 inhibitor efficacy. Here, we found tetrandrine (TET), an anti-tumor compound extracted from a medicinal plant commonly used in traditional Chinese medicine, has the ability to inhibit NSCLC tumor growth. Mechanistically, TET induces nuclear DNA damage and increases cytosolic dsDNA, thereby activating the STING/TBK1/IRF3 pathway, which in turn promotes the tumor infiltration of dendritic cells (DCs), macrophages, as well as CD8+ T cells in mice. In vivo imaging dynamically monitored the increased activity of the STING pathway after TET treatment and predicted the activation of the tumor immune microenvironment. We further revealed that the combination of TET with αPD-1 monoclonal antibody (αPD-1 mAb) yields significant anti-cancer effects by promoting CD8+ T cell infiltration and enhancing its cell-killing effect, which in turn reduced the growth of tumors and prolonged survival of NSCLC mice. Therefore, TET effectively eliminates NSCLC cells and enhances immunotherapy efficacy through the activation of the STING pathway, and combining TET with anti-PD-1 immunotherapy deserves further exploration for applications.

Novel sulfonyl-substituted tetrandrine derivatives for colon cancer treatment by inducing mitochondrial apoptosis and inhibiting PI3K/AKT/mTOR pathway.

Tetrandrine (TET) possesses multiple pharmacological activities and could suppress tumor proliferation via PI3K pathway inhibition. However, inferior antitumor activity and potential toxicity limit its clinical application. In the present study, a series of 14-sulfonamide and sulfonate TET derivatives were designed, synthesized, and evaluated for biological activities. Through structural-activity relationship studies, compound 3c with α, ß-unsaturated carbonyl group exhibited the most potent activity against all tested tumor cell lines (including Hela, HCT116, HepG2, MCF-7, and SHSY5Y), as well as negligible toxicity against normal cell lines LO2 and HEK293. Additionally, compound 3c effectively inhibited HCT116 and CT26 cell proliferation in vitro with increased cell proportion in the G2/M phase, activated the mitochondrial apoptosis pathway, and induced colon cancer cell apoptosis by suppressing the PI3K/AKT/mTOR pathway. The further molecular docking results confirmed that compound 3c is potentially bound to multiple residues in PI3K with a stronger binding affinity than TET. Ultimately, compound 3c dramatically suppressed tumor growth in the CT26 xenograft tumor model, without noticeable visceral toxicity detected in the high-dose group. In summary, compound 3c might present new insights for designing new PI3K inhibitors and be a potential candidate for colon cancer treatment.

Tetrandrine promotes the survival of the random skin flap via the PI3K/AKT signaling pathway.

Flaps are mainly used for wound repair. However, postoperative ischemic necrosis of the distal flap is a major problem, which needs to be addressed urgently. We evaluated whether tetrandrine, a compound found in traditional Chinese medicine, can prolong the survival rate of random skin flaps. Thirty-six rats were randomly divided into control, low-dose tetrandrine (25 mg/kg/day), and high-dose tetrandrine (60 mg/kg/day) groups. On postoperative Day 7, the flap survival and average survival area were determined. After the rats were sacrificed, the levels of angiogenesis, apoptosis, and inflammation in the flap tissue were detected with immunology and molecular biology analyses. Tetrandrine increased vascular endothelial growth factor and Bcl-2 expression, in turn promoting angiogenesis and anti-apoptotic processes, respectively. Additionally, tetrandrine decreased the expression of Bax, which is associated with the induction of apoptosis, and also decreased inflammation in the flap tissue. Tetrandrine improved the survival rate of random flaps by promoting angiogenesis, inhibiting apoptosis, and reducing inflammation in the flap tissue through the modulation of the PI3K/AKT signaling pathway.

Advances in nano-preparations for improving tetrandrine solubility and bioavailability.

Tetrandrine (TET) is a natural bis-benzylisoquinoline alkaloid isolated from Stephania species with a wide range of biological and pharmacologic activities; it mainly serves as an anti-inflammatory agent or antitumor adjuvant in clinical applications. However, limitations such as prominent hydrophobicity, severe off-target toxicity, and low absorption result in suboptimal therapeutic outcomes preventing its widespread adoption. Nanoparticles have proven to be efficient devices for targeted drug delivery since drug-carrying nanoparticles can be passively transported to the tumor site by the enhanced permeability and retention (EPR) effects, thus securing a niche in cancer therapies. Great progress has been made in nanocarrier construction for TET delivery due to their outstanding advantages such as increased water-solubility, improved biodistribution and blood circulation, reduced off-target irritation, and combinational therapy. Herein, we systematically reviewed the latest advancements in TET-loaded nanoparticles and their respective features with the expectation of providing perspective and guidelines for future research and potential applications of TET.

Borneol-modified docetaxel plus tetrandrine micelles for treatment of drug-resistant brain glioma.

OBJECTIVE: Glioma is the most common and deadly primary malignant tumor in adults. Treatment outcomes are ungratified due to the presence of blood-brain barrier (BBB), glioma stem cells (GSCs) and multidrug resistance (MDR). Docetaxel (DTX) is considered as a potential drug for the treatment of brain tumor, but its effectiveness is limited by its low bioavailability and drug resistance. Tetrandrine (TET) reverses the resistance of tumor cells to chemotherapy drugs. Borneol (BO) modified in micelles has been shown to promote DTX plus TET to cross the BBB, allowing the drug to better act on tumors. Therefore, we constructed BO-modified DTX plus TET micelles to inhibit chemotherapeutic drug resistance. SIGNIFICANCE: Provide a new treatment method for drug-resistant brain gliomas. METHODS: In this study, BO-modified DTX plus TET micelles were prepared by thin film dispersion method, their physicochemical properties were characterized. Its targeting ability was investigated. The therapeutic effect on GSCs was investigated by in vivo and in vitro experiments. RESULTS: The BO-modified DTX plus TET micelles were successfully constructed by thin film dispersion method, and the micelles showed good stability. The results showed that targeting micelles increased bEnd.3 uptake and helped drugs cross the BBB in vitro. And we also found that targeting micelles could inhibit cell proliferation, promote cell apoptosis and inhibit the expression of drug-resistant protein, thus provide a new treatment method for GSCs in vitro and in vivo. CONCLUSIONS: BO-modified DTX plus TET micelles may provide a new treatment method for drug-resistant brain gliomas.

Therapeutic effects of tetrandrine in inflammatory diseases: a comprehensive review.

Inflammation can be triggered by any factor. The primary pathological manifestations can be summarized as the deterioration, exudation, and proliferation of local tissues, which can cause systemic damage in severe cases. Inflammatory lesions are primarily localized but may interact with body systems to cause provocative storms, parenchymal organ lesions, vascular and central nervous system necrosis, and other pathologic responses. Tetrandrine (TET) is a bisbenzylquinoline alkaloid extracted from the traditional Chinese herbal medicine Stephania tetrandra, which has been shown to have significant efficacy in inflammatory conditions such as rheumatoid arthritis, hepatitis, nephritis, etc., through NF-κB, MAPK, ERK, and STAT3 signaling pathways. TET can regulate the body's imbalanced metabolic pathways, reverse the inflammatory process, reduce other pathological damage caused by inflammation, and prevent the vicious cycle. More importantly, TET does not disrupt body's normal immune function while clearing the body's inflammatory state. Therefore, it is necessary to pay attention to its dosage and duration during treatment to avoid unexpected side effects caused by a long half-life. In summary, TET has a promising future in treating inflammatory diseases. The author reviews current therapeutic studies of TET in inflammatory conditions to provide some ideas for subsequent anti-inflammatory studies of TET.

Efficacy and safety of tetrandrine in treatment of rheumatoid arthritis: a meta analysis. / æ±‰é˜²å·±ç”²ç´ æ²»ç–—ç±»é£Žæ¹¿å ³èŠ‚ç‚Žæœ‰æ•ˆæ€§å’Œå®‰å ¨æ€§çš„meta分析.

OBJECTIVES: To explore the efficacy and safety of tetrandrine in the treatment of rheumatoid arthritis. METHODS: Randomized controlled studies of tetrandrine in the treatment of rheumatoid arthritis were searched in China National Knowledge Infrastructure (CNKI), China Science and Technology Journal Database (VIP), World Wide Web Database, SinoMed, PubMed, Springer, Web of Science, the Cochrane Central Register of Controlled Trails database. A meta-analysis was conducted using R software version 3.5.3 to evaluate the clinical outcomes, including the total effective rate, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), rheumatoid factor (RF), visual analog scale (VAS) for pain, disease activity score (DAS), tender joint count (TJC), swollen joint count (SJC), and morning stiffness duration, as well as adverse events of RA patients. RESULTS: A total of 10 articles were included in the study. The meta-analysis indicated that tetrandrine significantly improved the total effective rate (OR=3.27, 95%CI: 2.01-5.37, P<0.01), ESR (SMD=1.12, 95%CI: 0.06-2.19, P<0.05), CRP (SMD=0.75, 95%CI: 0.28-1.22, P<0.01), VAS (SMD=0.55, 95%CI: 0.21-0.89, P<0.01), SJC (SMD=0.85, 95%CI: 0.40-1.31, P<0.01), TJC (SMD=1.16, 95%CI: 0.58-1.74, P<0.01), and morning stiffness (SMD=1.09, 95%CI: 0.68-1.50, P<0.01). However, no statistical significance was found in RF (SMD=1.70, 95%CI: －1.10-4.51, P>0.05) and DAS (SMD=0.26, 95%CI: －0.59-1.11, P>0.05). The overall incidence of adverse events associated with tetrandrine treatment for rheumatoid arthritis was 20% (95%CI: 12%-27%, I2=60%, P<0.05), with mild severity and favorable outcomes. CONCLUSIONS: Tetrandrine is effective in the treatment of RA patients with a mild degree of adverse events.

Enhanced Antitumor Efficacy of Novel Biomimetic Platelet Membrane-Coated Tetrandrine Nanoparticles in Nonsmall Cell Lung Cancer.

Nonsmall cell lung cancer (NSCLC) remains one of the leading causes of cancer-related death worldwide, posing a serious threat to global health. Tetrandrine (Tet) is a small molecule in traditional Chinese medicine with proven primary efficacy against multiple cancers. Although previous studies have demonstrated the potential anticancer effects of Tet on NSCLC, its poor water solubility has limited its further clinical application. Herein, a novel nanoparticle-based drug delivery system, platelet membrane (PLTM)-coated Tet-loaded polycaprolactone-b-poly(ethylene glycol)-b-polycaprolactone nanoparticles (PTeNPs), is proposed to increase the potency of Tet against NSCLC. First, tetrandrine nanoparticles (TeNPs) are created using an emulsion solvent evaporation method, and biomimetic nanoparticles (PTeNPs) are prepared by coating the nanoparticles with PLTMs. When coated with PLTMs, PTeNPs are considerably less phagocytized by macrophages than Tet and TeNPs. In addition, compared with Tet and TeNPs, PTeNPs can significantly inhibit the growth and invasion of NSCLC both in vitro and in vivo. With reliable biosafety, this drug delivery system provides a new method of sustained release and efficient anticancer effects against NSCLC, facilitating the incorporation of Tet in modern nanotechnology.

Tetrandrine synergizes with MAPK inhibitors in treating KRAS-mutant pancreatic ductal adenocarcinoma via collaboratively modulating the TRAIL-death receptor axis.

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive and lethal malignancies lacking effective therapies. KRAS mutations that occur in over 90% of PDAC are major oncogenic drivers of PDAC. The MAPK signaling pathway plays a central role in KRAS-driven oncogenic signaling. However, pharmacological inhibitors of the MAPK pathway are poorly responded in KRAS-mutant PDAC, raising a compelling need to understand the mechanism behind and to seek new therapeutic solutions. Herein, we perform a screen utilizing a library composed of 800 naturally-derived bioactive compounds to identify natural products that are able to sensitize KRAS-mutant PDAC cells to the MAPK inhibition. We discover that tetrandrine, a natural bisbenzylisoquinoline alkaloid, shows a synergistic effect with MAPK inhibitors in PDAC cells and xenograft models. Mechanistically, pharmacological inhibition of the MAPK pathway exhibits a double-edged impact on the TRAIL-death receptor axis, transcriptionally upregulating TRAIL yet downregulating its agonistic receptors DR4 and DR5, which may explain the limited therapeutic outcomes of MAPK inhibitors in KRAS-mutant PDAC. Of great interest, tetrandrine stabilizes DR4/DR5 protein via impairing ubiquitination-mediated protein degradation, thereby allowing a synergy with MAPK inhibition in inducing apoptosis in KRAS-mutant PDAC. Our findings identify a new combinatorial approach for treating KRAS-mutant PDAC and highlight the role of TRAIL-DR4/DR5 axis in dictating the therapeutic outcome in KRAS-mutant PDAC.

Tetrandrine slows the radiographic progression of progressive massive fibrosis in pneumoconiosis: a retrospective cohort study.

OBJECTIVE: This study aims to explore the clinical effect of Tetrandrine (Tet) on progressive massive fibrosis (PMF) of pneumoconiosis. METHODS: This retrospective study collected 344 pneumoconiosis patients with PMF, and 127 were eligible for the final analysis, including 57 patients in the Tet group and 70 patients in the control group. The progress of imaging and lung function were compared between the two groups. RESULTS: After 13 months (median) of treatment, the size of PMF was smaller in the Tet group than that in the control group (1526 vs. 2306, p=0.001), and the size was stable in the Tet group (1568 vs. 1526, p= 0.381), while progressed significantly in the control group (2055 vs. 2306, p=0.000). The small nodule profusion and emphysema were also milder than that in the control group (6.0 vs. 7.5, p=0.046 and 8.0 vs. 12, p=0.016 respectively). Pulmonary ventilation function parameters FVC and FEV1 improved in the Tet group (3222 vs. 3301, p=0.021; 2202 vs. 2259, p=0.025 respectively) and decreased in the control group (3272 vs. 3185, p= 0.00; 2094 vs. 1981, p=0.00 respectively). FEV1/FVC was also significantly higher in the Tet group than that in the control group (68.45vs. 60.74, p=0.001). However, similar result was failed to observed for DLco%, which showed a significant decrease in both groups. CONCLUSION: Tet has shown great potential in the treatment of PMF by slowing the progression of pulmonary fibrosis and the decline of lung function.

Evaluating the Efficacy of Polyglycolic Acid-Loading Tetrandrine Nanoparticles in the Treatment of Dry Eye.

INTRODUCTION: Dry eye disease (DED) is a multifactor-induced disease accompanied by increased osmolarity of the tear film and inflammation of the ocular surface. Traditional anti-inflammation agent corticosteroids applied in DED treatment could result in high intraocular pressure, especially in long-term treatment. Therefore, we explored a nano drug that aimed to block the formation pathway of DED which had anti-inflammatory, sustained release, and good biocompatibility characteristics in this study. METHODS: We prepared a novel nanomedicine (Tet-ATS@PLGA) by the thin film dispersion-hydration ultrasonic method and detected its nanostructure, particle size, and zeta potential. Flow cytometry was used to detect the cell survival rate of each group after 24 h of drug treatment on inflammed Statens Seruminstitut Rabbit Corneal (SIRC) cells. Observed and recorded corneal epithelial staining, tear film rupture time, and Schirmer test to detect tear secretion on the ocular surface of rabbits. The corneal epithelial thickness, morphology, and number of bulbar conjunctival goblet cells were recorded by H&E staining. Finally, we detected the expression of VEGF, IL-1ß, PGE2, and TNF-α by cellular immunofluorescence staining and enzyme-linked immunosorbent assay (ELISA). RESULTS: The encapsulation efficiency and drug loading of Tet-ATS@PLGA were 79.85% and 32.47%, respectively. At eye surface temperature, Tet can easily release from Tet-ATS@PLGA while that it was difficult to release at storage temperature and room temperature. After 2 weeks medication, Tet-ATS@PLGA can effectively improve the tear film rupture time and tear secretion time in a DED model (p <0.05). Compared with the normal group (62.34 ± 4.86 mm), the thickness of corneal epithelium in ATS (29.47 ± 3.21 mm), Tet-ATS (46.23 ± 2.87 mm), and Tet-ATS@PLGA (55.76 ± 3.95 mm) gradually increased. Furthermore, the flow cytometry indicated that Tet-ATS@PLGA can effectively promote the apoptosis of inflammatory SIRC cells, and the cellular immunofluorescence and ELISA experiments showed that the expression intensity of inflammatory factors such as VEGF, IL-1ß, PGE2, and TNF-α decreased in this process. Interestingly, Tet also had the effect of reducing intraocular pressure. CONCLUSION: Tet-ATS@PLGA can effectively promote the apoptosis of inflammatory corneal epithelial cells, thus inhibiting the expression of inflammatory factors to block the formation of DED and improve the secretion of tear on the ocular surface.

A (Traditional Chinese Medicine) TCM-Inspired Doxorubicin Resistance Reversing Strategy: Preparation, Characterization, and Application of a Co-loaded pH-Sensitive Liposome.

In this study, nano-strategy for combined medication of active compounds from traditional Chinese medicine herbs was proposed to achieve the synergistic effects of inhibiting the doxorubicin (DOX) resistance, reducing the cardio-toxicity, and improving the treatment efficacy simultaneously. Dihydroartemisinin (DHA) and tetrandrine (TET) were co-delivered for the first time to treat DOX resistance of breast cancer with multi-pathway mechanism. Tumor micro-environment sensitivity prescription was adopted to enhance the reversal effect of DOX resistance nearly 50 times (resistance index, RI was 46.70) and uptake ability. The DHA-TET pH-sensitive liposomes (DHA-TET pH-sensitive LPs) had a good spherical structure and a uniform dispersion structure with particle size, polydispersity index (PDI), and zeta potential of 112.20 ± 4.80 nm, 0.20 ± 0.02, and - 8.63 ± 0.74 Mv, and was stable until 14 days under the storage environment of 4°C and for 6 months at room temperature environment. With the DOX resistance reversing ability increased, the inhibition effect of DHA-TET pH-sensitive LPs on both MCF-7/ADR cells and MCF-7 cells was significantly enhanced; meanwhile, the toxicity on cardiac cell (H9c2) was lowered. Ferroptosis induced by the DHA was investigated showing that the intracellular reactive oxygen species (ROS) and lipid peroxidation were increased to promote the synergistic effect through the due-loaded nano-carrier, providing a promising alternative for future clinical application.

Preparation of Tetrandrine Nanocrystals by Microfluidic Method and Its In Vitro and In Vivo Evaluation.

The anti-hepatocellular carcinoma effects of TET are acknowledged, but its application is hindered by its poor water solubility and low bioavailability. Conventional methods for nanocrystal preparation are laborious and lack control. To address these limitations, we propose employing the microfluidic method in the preparation of TET nanocrystals, aiming to enhance the aforementioned constraints. The objectives of this study were to prepare TET nanocrystals (TET-NC@GL) using a Y-microfluidic method with glycyrrhetinic acid (GL) as a stabilizer. The optimal preparation prescription was determined through a single-factor test and Box-Behnken response surface method. Additionally, the nanocrystals prepared with the commonly used stabilizer polyvinylpyrrolidone K30 (PVPK30), known as TET-NC@PVPK30, were characterized and evaluated for their toxicity to HepG2 cells. Hybridized nanocrystals (TET-HNC@GL and TET-HNC@PVPK30) were synthesized using a water-soluble aggregation-induced emission (AIE) fluorescent probe (TVP). Qualitative and quantitative cellular uptake experiments were conducted using these hybridized nanocrystals. Conducting in vivo pharmacokinetic assays evaluates the relative bioavailability of nanocrystals. The results indicated that TET-NC@GL, optimized using the response surface method, had a particle size of 136.47 ± 3.31 nm and a PDI of 0.219 ± 0.002. The administration of TET-NC@GL significantly enhanced the cell inhibition rate compared to the TET group and the TET-NC@PVPK30 group (P < 0.01). Moreover, the qualitative and quantitative cellular uptake results revealed a significant enhancement in cellular uptake in the TET-HNC@GL administration group compared to the TET-HNC@PVPK30 group (P < 0.01). In vivo pharmacokinetic results showed that the bioavailability of TET-NC@GL group was 3.5 times higher than that of the TET group. The results demonstrate the successful preparation of TET-NC@GL nanocrystals.

[Drug clinical comprehensive evaluation of tetrandrine in the treatment of pneumoconiosis].

Objective: To analyze the safety, effectiveness, economics, innovation, suitability and accessibility of tetrandrine in the treatment of pneumoconiosis, and provide evidence-based basis for health policy decision-making and clinical practice. Methods: In July 2022, the system searched PubMed, Embase, the Cochrane Library, CNKI, Wanfang, SinoMed databases (the retrieval time was from the establishment of the database to June 30, 2022), screened the documents that meet the standards, extracted and evaluated the data, and used the "HTA checklist" developed by the International Network of Agencies for Health Technology Assessment (INAHTA) to evaluate the HTA report. AMSTAR-2 Scale was used to evaluate the quality of systematic evaluation/Meta analysis. CHEERS Scale was used to evaluate the quality of pharmacoeconomics research. The included cohort study or case-control study was evaluated with the Newcastle-Ottawa Scale. The included randomized controlled trial (RCT) studies were evaluated using the Cochrane Risk Bias Assessment Tool (Cochrane RCT) quality evaluation criteria. Comprehensive comparison and analysis based on the characteristics of the data included in the study. Results: A total of 882 related literatures were detected from the initial screening. According to relevant standards, 8 RCT studies were finally selected for analysis. Statistical results showed that basic treatment with tetrandrine could better improve FEV(1) (MD=0.13, 95%CI: 0.06-0.20, P<0.001), FEV(1)/FVC (MD=4.48, 95%CI: 0.61-8.35, P=0.02) and clinical treatment efficiency. Tetrandrine had a low incidence of adverse reactions. The affordability coefficient of tetrandrine tablets was 0.295-0.492. Conclusion: Tetrandrine can improve the clinical symptoms and pulmonary ventilation function of pneumoconiosis patients, most of the adverse reactions are mild, and the clinical application is safe.

Tetrandrine, an immunosuppressive alkaloid isolated from Steohania tetrandra S. Moore, induces the generation of Treg cells through enhancing fatty acid oxidation.

Our previous studies have demonstrated that tetrandrine can induce the generation of regulatory T (Treg) cells in vitro and in vivo. But, the underlying mechanism of tetrandrine remains obscure. Naïve CD4+ T cells are isolated from the mesenteric lymph nodes of mice for the differentiation of Treg cells. Flow cytometry is used to detect the frequencies of Treg cells. Non-targeted metabolomics analysis based on UHPLC-QTOF/MS is performed to assess the intracellular metabolic profiles. ChIP-PCR analysis is conducted to detect the level of H3K27ac at Foxp3 promoter and CNS regions. Tetrandrine treatment alters the metabolic profile of Treg cells, and pathway enrichment of differential metabolites mainly involves fatty acid oxidation (FAO). Tetrandrine promotes the mRNA expression of carnitine palmitoyl transferase-1, and increases the level of acetyl coenzyme A (acetyl-CoA) and the intracellular oxygen consumption rate. Either CPT1 inhibitor (etomoxir) or siRNA markedly diminishes the promotion of tetrandrine on Treg cell differentiation. Furthermore, tetrandrine enhances the acetylation of H3K27 in the promoter and CNS1 regions of Foxp3 through the acetyl-CoA derived from FAO. In the mice with collagen-induced arthritis, tetrandrine also induces Treg cell generation through FAO pathway. In addition, tetrandrine enhances the immunosuppressive function of Treg cells both in vitro and in vivo. The findings indicate that tetrandrine promotes Treg cell differentiation by enhancing FAO-mediated Foxp3 acetylation, and the CPT1-mediated FAO can serve as the target for the discovery of novel inducers of Treg cell generation.

Tetrandrine inhibits RANKL-induced osteoclastogenesis by promoting the degradation of TRAIL.

BACKGROUND: Tetrandrine, a bisbenzylisoquinoline (BBI) alkaloid extracted from Stephania tetrandra (S. Moore), and is widely used in several diseases such as tuberculosis, hyperglycemia, malaria, and tumors. Tetrandrine was recently shown to prevent bone loss in ovariectomized mice. However, the specific mechanism underlying osteoclastogenesis inhibition remains unclear. METHODS: Tetrandrine's cytotoxicity to cells was determined using the Cell Counting Kit-8 assay. Tartrate-resistant acid phosphatase staining, immunofluorescence and bone resorption assay were performed to evaluate osteoclasts' differentiation and absorption capacity. The bone-forming capacity was assessed using alkaline phosphatase and Alizarin red S staining. qPCR and Western blotting were applied to assess the related genes and protein expression. Tetrandrine's impact on TRAIL was demonstrated through a co-immunoprecipitation assay. Animal experiments were performed for the detection of the therapeutic effect of Tetrandrine on osteoporosis. RESULTS: Tetrandrine attenuated RANKL-induced osteoclastogenesis and decreased the related gene expression. The co-immunoprecipitation assay revealed that Tetrandrine administration accelerated the ubiquitination of TNF-related apoptosis-inducing ligand (TRAIL), which was subsequently degraded. Moreover, TRAIL overexpression was found to partially reverse the Tetrandrine-induced inhibition of osteoclastogenesis. Meanwhile, Tetrandrine significantly inhibited the phosphorylation of p38, p65, JNK, IKBα and IKKα/ß, while the TRAIL overexpression weakened this effect. In addition, Tetrandrine promoted osteogenesis and inhibited the TRAIL expression in osteoblasts. Tetrandrine consistently improved bone destruction by stimulating bone formation and inhibiting bone resorption in an OVX-induced mouse model. CONCLUSION: Tetrandrine inhibits RANKL-induced osteoclastogenesis by promoting TRAIL degradation and promotes osteoblast differentiation, suggesting its potential in antiosteopenia pharmacotherapy.

Tetrandrine attenuates intestinal epithelial barrier defects caused by colitis through promoting the expression of Occludin via the AhR-miR-429 pathway.

The elevated intestinal permeability due to mucosal barrier defects is not only secondary to inflammatory bowel disease but also precedes enteritis. Tetrandrine, a bisbenzyl isoquinoline alkaloid isolated from the dried roots of Stephamis tetlandra S. Moor, was previously demonstrated to ameliorate colitis induced by dextran sulfate sodium (DSS) in mice. Here, we investigate whether and how tetrandrine protects against the disruption of the intestinal epithelial barrier under colitis condition. The data show that oral administration of tetrandrine significantly counteracted the increase of intestinal permeability in DSS-treated mice, enhanced the mRNA and protein expression of Occludin and Claudin1 in the colon, but hardly affected the expression of ZO-1 and Mucin2. In vitro, tetrandrine treatment rescued the decrease of monolayer transmembrane resistance and the increase of epithelial cell permeability induced by TNF-α, upregulated the expression of Occludin, and downregulated the expression of Claudin1 but did not affect the expression of ZO-1. The siRNA of Occludin largely weakened the protective effect of tetrandrine on the epithelial barrier function in Caco-2 cells. MiR-429 mimic obviously counteracted the upregulation of tetrandrine on the expression of Occludin and the amelioration on epithelial barrier defects, in contrast, miR-429 inhibitor showed the opposite effects. The antagonist (CH223191) and siAhR of aryl hydrocarbon receptor (AhR) nearly completely diminished the effects of tetrandrine, including inhibition of the miR429 expression, the upregulation of Occludin expression, and amelioration of intestinal epithelial barrier defects in Caco-2 cells. In colitis mice, CH223191 significantly weakened the protective effect of tetrandrine on colitis and intestinal mucosal barrier and diminished the downregulation on miR-429 expression and the promotion on Occludin expression in the colon. In summary, tetrandrine can attenuate the intestinal epithelial barrier defects in colitis through promoting Occludin expression via the AhR/miR-429 pathway, and it might be used to treat colitis as a barrier protector.

Tetrandrine ameliorates cognitive deficits and mitigates tau aggregation in cell and animal models of tauopathies.

BACKGROUND: Tauopathies are neurodegenerative diseases that are associated with the pathological accumulation of tau-containing tangles in the brain. Tauopathy can impair cognitive and motor functions and has been observed in Alzheimer's disease (AD) and frontotemporal dementia (FTD). The aetiology of tauopathy remains mysterious; however, recent studies suggest that the autophagic-endolysosomal function plays an essential role in the degradation and transmission of pathological tau. We previously demonstrated that tetrandrine could ameliorate memory functions and clear amyloid plaques in transgenic AD mice by restoring autophagic-endolysosomal function. However, the efficacy of tetrandrine and the associated therapeutic mechanism in tauopathies have not been evaluated and elucidated. METHODS: Novel object recognition, fear conditioning and electrophysiology were used to evaluate the effects of tetrandrine on memory functions in transgenic tau mice. Western blotting and immunofluorescence staining were employed to determine the effect of tetrandrine on autophagy and tau clearance in vivo. Calcium (Ca2+) imaging and flow cytometry were used to delineate the role of pathological tau and tetrandrine in lysosomal Ca2+ and pH homeostasis. Biochemical BiFC fluorescence, Western blotting and immunofluorescence staining were used to evaluate degradation of hyperphosphorylated tau in vitro, whereas coculture of brain slices with isolated microglia was used to evaluate tau clearance ex vivo. RESULTS: We observed that tetrandrine treatment mitigated tau tangle development and corrected memory impairment in Thy1-hTau.P301S transgenic mice. Mechanistically, we showed that mutant tau expression disrupts lysosome pH by increasing two-pore channel 2 (TPC2)-mediated Ca2+ release, thereby contributing to lysosome alkalinization. Tetrandrine inhibits TPC2, thereby restoring the lysosomal pH, promotes tau degradation via autophagy, and ameliorates tau aggregation. Furthermore, in an ex vivo assay, we demonstrated that tetrandrine treatment promotes pathological tau clearance by microglia. CONCLUSIONS: Together, these findings suggest that pathological tau disturbs endolysosomal homeostasis to impair tau clearance. This impairment results in a vicious cycle that accelerates disease pathogenesis. The success of tetrandrine in reducing tau aggregation suggests first, that tetrandrine could be an effective drug for tauopathies and second, that rescuing lysosomal Ca2+ homeostasis, thereby restoring ALP function, could be an effective general strategy for the development of novel therapies for tauopathies.

Tetrandrine Ameliorates Traumatic Brain Injury by Regulating Autophagy to Reduce Ferroptosis.

Traumatic brain injury (TBI) is the leading cause of death and disability in trauma patients. However, the effects and mechanism of autophagy after TBI remain unclear. This study aimed to investigate whether tetrandrine could ameliorate TBI through autophagy to reduce ferroptosis. A mice model for TBI was implemented. Behavioral and histomorphological experiments were performed to evaluate outcomes of the mice. The ferroptosis levels was detected by Perls staining. Enzyme-linked immunosorbent assay (ELISA) was applied to detect malondialdehyde (MDA), glutathione (GSH), and glutathione peroxidase 4 (GPX4) levels in the brain tissue. Western blot test was performed to detect Beclin 1, light chain 3 (LC3) II/I, p62, GPX4, SCL7A11, and ferritin heavy chain 1 (FTH1) levels, and the expression of LC3B, Beclin 1, GPX4, and FTH1 in the brain tissue was detected by immunofluorescence (IF). The behavioral and histomorphological results demonstrated that tetrandrine improved the neurological function and cerebral edema on days 1, 3, and 7 after TBI. The ELISA results suggested that tetrandrine reduced the MDA concentration and increased GSH concentration on days 1, 3, and 7 after TBI. IF staining and Perls staining reflected that tetrandrine promoted autophagy and inhibited ferroptosis on days 1, 3, and 7 after TBI, respectively. Tetrandrine further improved the neurological function, cerebral edema, autophagy, and ferroptosis on days 1, 3, and 7 after TBI after adding the autophagy inducer rapamycin. The effect of TET in alleviating TBI increased with the increase of time and dose. Tetrandrine ameliorated TBI by regulating autophagy to reduce ferroptosis, providing a new therapeutic strategy for TBI.