Protective effect of sarsasapogenin in TNBS induced ulcerative colitis in rats associated with downregulation of pro-inflammatory mediators and oxidative stress

Anti-inflammatory and immunomodulatory effects of Glycyrrhiza uralensis fisch. On ulcerative colitis in rats: Role of nucleotide-binding oligomerization domain 2/receptor-interacting protein 2/nuclear factor-kappa B signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

As a traditional Chinese herb, Glycyrrhiza uralensis Fisch. exhibits a range of pharmacological activities, including anti-inflammatory, immunomodulatory and antifibrotic, which suggests its therapeutic potential for inflammatory bowel disease, and related mechanisms need to be further clarified.

AIM OF THE STUDY

To evaluate in vivo anti-inflammatory effects of Glycyrrhiza uralensis Fisch. aqueous extract (GE) on 2, 4, 6-trinitrobenzene sulfonic acid (TNBS)-induced acute experimental colitis rat model and its potential mechanisms.

MATERIALS AND METHODS

The protective effects of GE on IBD were evaluated in vivo using a TNBS and 75% ethanol-induced ulcerative colitis (UC) model. The evaluated clinical and anatomical indexes included body weight, colon length, disease activity index (DAI) score, Colonic Mucosal Damage Index (CMDI) score. The percentages of T, B lymphocytes, NK cells, and macrophages in the colon, spleen and peripheral blood were investigated by flow cytometry. Colon tissues were stained with Hematoxylin and Eosin (H&E) for histopathological examination. After using transcriptome sequencing to screen targeted genes, the expression of related genes was detected by Real-Time Quantitative Polymerase Chain Reaction (RT-qPCR) and Western blot (WB).

RESULTS

The decrease of food intake, soft feces, and colon histopathological injury were observed in colitis rats, which were alleviated by GE, with the best therapeutic effect in the 100 mg/kg GE group. The average CMDI scores of colon in UC rats were decreased from 4.0 to 1.5. The percentages of CD161a+ NK cells, CD68+ total macrophages, CD68+/CD161a+ M1 type macrophages, CD3+ T lymphocytes, and CD45RA+ B lymphocytes were decreased in the spleen and colon. The transcriptomics analysis of colon showed that the results were mainly related to the TNF signaling pathway and NF-κB signaling pathway. The RT-qPCR and WB results determined that the upregulated expression of nucleotide-binding oligomerization domain 2 (NOD2), receptor-interacting protein 2 (RIP2), nuclear factor-kappa B (NF-κB), tumor necrosis factor-α (TNF-α) in the colon of the colitis rats were downregulated by GE treatment.

CONCLUSION

The research results indicate that GE can exert therapeutic effects on TNBS-induced UC in rats by alleviating cell injury and inflammatory responses, and its mechanisms may be related to the regulation of NOD2/RIP2/NF-κB signaling pathway.

Olsalazine pretreatment augments chemosensitivity of gemcitabine in hepatocellular carcinoma

Recently, olsalazine a DNA hypomethylating agent was found to inhibit the growth of breast cancer cells. The present study was carried out to evaluate the effects of olsalazine pretreatment in the potentiation of chemosensitivity of gemcitabine for the treatment of hepatocellular carcinoma (HCC). In silico molecular docking was performed to analyze the interaction of olsalazine and gemcitabine with DNMT1 and DNA, respectively, using the AutoDock tools 1.5.6. Cytotoxicity of olsalazine, gemcitabine, and combination were measured on human HePG2 cells using MTT assay. Antiproliferative effects were assessed using animal model of N-nitrosodiethylamine and carbon tetrachloride-induced HCC. Treatment was initiated from 8th week of induction to 11th week and change in body weight, liver weight, and survival rate were measured. Following treatment, blood samples were collected for estimation serum biochemistry. Blood serum was used for the estimation of inflammatory cytokines tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6), C-reactive protein [CRP], lactate dehydrogenase (LDH), and P53 levels. Oxidative stress markers were measured in liver tissue homogenates. Histopathology and immunohistochemistry (IHC) were performed on liver sections to detect the morphological changes and P53 expression. Docking analysis revealed the interactions between olsalazine and DNMT1 with a binding energy score of -5.34 and gemcitabine and DNA with a binding energy score of -5.93. Olsalazine pretreatment potentiated the antiproliferative effect of gemcitabine in cell line study. In the group receiving olsalazine pretreatment showed significant reductions in relative liver weight and improved survival rate of gemcitabine treatment group. Serum biochemical markers: serum glutamate pyruvate transaminase, serum glutamic oxaloacetic transaminase, alkaline phosphatase, and bilirubin revealed improved liver functions. Olsalazine pretreatment also reduced the levels of inflammatory markers like CRP, LDH, TNF-α, and IL-6 and oxidative stress markers dose dependently. Histopathology and IHC showed improved liver morphology with potentiated the induction of P53 upon olsalazine pretreatment in combination with gemcitabine. In conclusion, sequential combination of olsalazine and gemcitabine improved the treatment outcomes during the progression of HCC.

Probiotic Bacillus licheniformis MCC2514 and Bifidobacterium breve NCIM 5671 Regulates GATA3 and Foxp3 Expression in the Elevated Disease Condition

TNBS-induced ulcerative colitis was evaluated using Bacillus licheniformis MCC 2514 (B. licheniformis) and Bifidobacterium breve NCIM 5671 (Bf. breve) as immune modulators. The study aims to analyze probiotic efficiency of ulcerative colitis induced by TNBS in Wistar rats. The tumor-like structure was found in the colon of TNBS inflammation-induced rats. Nitric oxide production was inhibited by about 65.2% fed with combination of bacteria and C-reactive protein, and decreased by 12% and 10.8% upon supplementing B. licheniformis and Bf. breve against the TNBS-treated rats, respectively. Liver damage was observed in the TNBS-treated rats; addition of probiotic bacteria reduced SGPT (75.4%) and SGOT (42.5%). On TNBS treatment, the transcriptional factor responsible for Th2 cell immune response (GATA3) was analyzed, and the elevation in gene expression (5.31-fold) was found. The FOXP-3 responsible for T-regulatory cells was expressed about 0.91-fold upon the treatment with a combination of bacteria. The expression of antioxidant genes such as iNOS (1.11-fold), GPx (1.29-fold), and PON1 (1.48-fold) has been increased when compared with that of the TNBS-treated group. The cytokines specific to Th2-driven immune response, such as IL-4, IL-5, and TNF-α, were reduced upon feeding the bacteria. It is observed that the B. licheniformis and Bf. breve used in the study have reduced Th2-driven immune response.

Exploring the autophagy-related pathogenesis of active ulcerative colitis

BACKGROUND

The pathogenesis of ulcerative colitis (UC) is complex, and recent therapeutic advances remain unable to fully alleviate the condition.

AIM

To inform the development of novel UC treatments, bioinformatics was used to explore the autophagy-related pathogenesis associated with the active phase of UC.

METHODS

The GEO database was searched for UC-related datasets that included healthy controls who met the screening criteria. Differential analysis was conducted to obtain differentially expressed genes (DEGs). Autophagy-related targets were collected and intersected with the DEGs to identiy differentially expressed autophagy-related genes (DEARGs) associated with active UC. DEARGs were then subjected to KEGG, GO, and DisGeNET disease enrichment analyses using R software. Differential analysis of immune infiltrating cells was performed using the CiberSort algorithm. The least absolute shrinkage and selection operator algorithm and protein-protein interaction network were used to narrow down the DEARGs, and the top five targets in the Dgree ranking were designated as core targets.

RESULTS

A total of 4822 DEGs were obtained, of which 58 were classified as DEARGs. SERPINA1, BAG3, HSPA5, CASP1, and CX3CL1 were identified as core targets. GO enrichment analysis revealed that DEARGs were primarily enriched in processes related to autophagy regulation and macroautophagy. KEGG enrichment analysis showed that DEARGs were predominantly associated with NOD-like receptor signaling and other signaling pathways. Disease enrichment analysis indicated that DEARGs were significantly linked to diseases such as malignant glioma and middle cerebral artery occlusion. Immune infiltration analysis demonstrated a higher presence of immune cells like activated memory CD4 T cells and follicular helper T cells in active UC patients than in healthy controls.

CONCLUSION

Autophagy is closely related to the active phase of UC and the potential targets obtained from the analysis in this study may provide new insight into the treatment of active UC patients.

Responsive nanosystems for targeted therapy of ulcerative colitis: Current practices and future perspectives

The pharmacological approach to treating gastrointestinal diseases is suffering from various challenges. Among such gastrointestinal diseases, ulcerative colitis manifests inflammation at the colon site specifically. Patients suffering from ulcerative colitis notably exhibit thin mucus layers that offer increased permeability for the attacking pathogens. In the majority of ulcerative colitis patients, the conventional treatment options fail in controlling the symptoms of the disease leading to distressing effects on the quality of life. Such a scenario is due to the failure of conventional therapies to target the loaded moiety into specific diseased sites in the colon. Targeted carriers are needed to address this issue and enhance the drug effects. Conventional nanocarriers are mostly readily cleared and have nonspecific targeting. To accumulate the desired concentration of the therapeutic candidates at the inflamed area of the colon, smart nanomaterials with responsive nature have been explored recently that include pH responsive, reactive oxygen species responsive (ROS), enzyme responsive and thermo - responsive smart nanocarrier systems. The formulation of such responsive smart nanocarriers from nanotechnology scaffolds has resulted in the selective release of therapeutic drugs, avoiding systemic absorption and limiting the undesired delivery of targeting drugs into healthy tissues. Recent advancements in the field of responsive nanocarrier systems have resulted in the fabrication of multi-responsive systems i.e. dual responsive nanocarriers and derivitization that has increased the biological tissues and smart nanocarrier's interaction. In addition, it has also led to efficient targeting and significant cellular uptake of the therapeutic moieties. Herein, we have highlighted the latest status of the responsive nanocarrier drug delivery system, its applications for on-demand delivery of drug candidates for ulcerative colitis, and the prospects are underpinned.

Reduction of high glucose-induced oxidative injury in human retinal pigment epithelial cells by sarsasapogenin through inhibition of ROS generation and inactivation of NF-κB/NLRP3 inflammasome pathway

BACKGROUND

Hyperglycemia-induced accumulation of reactive oxygen species (ROS) is a major risk factor for diabetic retinopathy (DR). Sarsasapogenin is a natural steroidal saponin that is known to have excellent antidiabetic effects and improve diabetic complications, but its potential efficacy and mechanism for DR are unknown.

OBJECTIVES

The current study was designed to explore whether sarsasapogenin inhibits hyperglycemia-induced oxidative stress in human retinal pigment epithelial (RPE) ARPE-19 cells and to elucidate the molecular mechanisms.

METHODS

To mimic hyperglycemic conditions, ARPE-19 cells were cultured in medium containing high glucose (HG). The suppressive effects of sarsasapogenin on HG-induced cell viability reduction, apoptosis and ROS production were investigated. In addition, the relevance of the nuclear factor-kappa B (NF-κB)/NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome signaling pathway was explored to investigate the mechanism of antioxidant and anti-inflammatory activity of sarsasapogenin.

RESULTS

Sarsasapogenin significantly alleviated cytotoxicity and apoptosis in HG-treated ARPE-19 cells through inhibition of intracellular ROS generation. Sarsasapogenin also effectively attenuated HG-induced excess accumulation of mitochondrial superoxide, reduction of glutathione content, and inactivation of manganese superoxide dismutase and glutathione peroxidase. The HG condition markedly increased the expression and maturation of interleukin (IL)-1β and IL-18 through the activation of the NF-kB signaling pathway, whereas sarsasapogenin reversed these effects. Moreover, although the expression of NLRP3 inflammasome multiprotein complex molecules was increased in ARPE-19 cells cultured under HG conditions, their levels remained similar to the control group in the presence of sarsasapogenin.

CONCLUSION

Sarsasapogenin could protect RPE cells from HG-induced injury by inhibiting ROS generation and NF-κB/NLRP3 inflammasome pathway, suggesting its potential as a therapeutic agent to improve the symptoms of DR.

Histone Modification of Colorectal Cancer by Natural Products

Natural products play important roles in the pathogenesis of many human malignancies, including colorectal cancer, and can act as a gene regulator in many cancers. They regulate malignant cell growth through many cellular signal pathways, including Rac family small GTPase 1 (RAC1)/PI3K/AKT (α-serine/threonine-protein kinase), mitogen-activated protein kinase (MAPK), Wnt/β-catenin pathway, transforming growth factor-β (TGF-β), Janus kinase and signal transducer and activator of transcription (JAK-STAT), nuclear factor kappa-B (NF-κB), the Notch pathway, Hippo pathway, and Hedgehog pathway. In this review, we describe the epigenetic roles of several natural products, e.g., platycodin D (PD), ginsenoside Rd, tretinoin, Rutin, curcumin, clove extract, betulinic acid, resveratrol, and curcumin, in colorectal cancer, including their impact on colorectal cancer cell proliferation, apoptosis, invasion, migration, and anti-chemotherapeutic resistance. The aim is to illustrate the epigenetic mechanisms of action of natural products in cancer prevention and treatment, and to provide (1) a theoretical basis for the study of the role of epigenetics in influencing colorectal cancer; (2) new directions for studying the occurrence, development, and prognosis of colorectal cancer; and (3) new targets for treating and preventing colorectal cancer.

Dietary Supplementation of Ancientino Ameliorates Dextran Sodium Sulfate-Induced Colitis by Improving Intestinal Barrier Function and Reducing Inflammation and Oxidative Stress

Ancientino, a complex dietary fiber supplement mimicking the ancient diet, has improved chronic heart failure, kidney function, and constipation. However, its effect on ulcerative colitis is unknown. This study explores the impact of Ancientino on colitis caused by dextran sulfate sodium (DSS) and its mechanisms. Data analyses showed that Ancientino alleviated bodyweight loss, colon shortening and injury, and disease activity index (DAI) score, regulated levels of inflammatory factors (tumor necrosis factor-alpha (TNF-α), interleukin-10 (IL-10), interleukin-1 beta (IL-1β), and interleukin 6 (IL-6)), reduced intestinal permeability (d-lactate and endotoxin), fluorescein isothiocyanate-dextran (FITC-dextran), and diamine oxidase (DAO), repaired colonic function (ZO-1 and occludin), and suppressed oxidative stress (superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), and malondialdehyde (MDA)) in vivo and in vitro. In short, this study demonstrated that Ancientino alleviates colitis and exerts an anticolitis effect by reducing inflammatory response, suppressing oxidative stress, and repairing intestinal barrier function. Thus, Ancientino may be an effective therapeutic dietary resource for ulcerative colitis.

Anti-inflammatory and antioxidant activity of astragalus polysaccharide in ulcerative colitis: A systematic review and meta-analysis of animal studies

Background: Accumulated evidence indicates that astragalus polysaccharide (APS) may have a beneficial impact on ulcerative colitis (UC) by suppressing inflammation and decreasing oxidative stress. Nevertheless, the credibility of the evidence for this practice is unclear. Therefore, we intended to conduct a systematic review and meta-analysis of animal studies to assess the anti-inflammatory and antioxidant activity of APS when used in the treatment of UC. Methods: Electronic bibliographic databases including PubMed, EMBASE, Web of Science, Chinese Biomedical Literature (CBM), Wanfang Database, CQVIP Database and China National Knowledge Infrastructure (CNKI) were retrieved for relevant animal studies. The methodological quality of animal studies was evaluated based on the SYstematic Review Center for Laboratory animal Experimentation (SYRCLE's RoB tool). A meta-analysis was performed according to the Cochrane Handbook for Systematic Reviews of Interventions by using STATA 12.0 software. This study was registered with PROSPERO, number CRD42021272595. Results: Twenty qualified publications involving 591 animals were included in this study. There was a significant association of APS with levels of disease activity index (DAI), colon macroscopic damage index (CMDI), colon histopathologic score (CHS), myeloperoxidase (MPO), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-1β (IL-1β), superoxide dismutase (SOD) and malondialdehyde (MDA) compared with that in the control group. Sensitivity analysis that eliminated one study at each stage did not change these results. Egger's test and funnel plot showed that publication bias was existed. Conclusion: In this meta-analysis, APS treatment significantly mitigated colonic damage by reducing the levels of MPO, TNF-α, IL-6, IL-1β, and MDA and recovering the SOD activity. These results demonstrated a protective role of APS in the treatment of UC and showed that the anti-inflammatory and antioxidant activity were implicated in the underlying mechanisms. Hence, APS may represent a promising candidate for treating UC. However, due to potential publication bias, a cautious interpretation is needed. Systematic Review Registration: (https://www.crd.york.ac.uk/PROSPERO/).

Preventive effect of Chinese dwarf cherry [Cerasus humilis (Bge.) Sok.] fermentation juice on dextran sulfate sodium-induced ulcerative colitis rats through the regulation of IgA and the intestinal immune barrier

Ulcerative colitis (UC) is a modern, refractory disease, and studies have shown that UC is closely associated with the gut microbiota and intestinal immune barrier. This study evaluated the protective effects and regulatory mechanism of Chinese dwarf cherry [Cerasus humilis (Bge.) Sok.] fermentation juice (CFJ) on UC induced by dextran sulfate sodium (DSS). The results indicated that CFJ could significantly modulate the oxidative stress index in the serum and colon, observably reduce MPO and NO activity, and increase the SOD level. CFJ significantly downregulated the levels of TNF-α, IL-1β and IL-6 and reduced inflammation caused by DSS. SIgA and short-chain fatty acids (SCFAs) levels were effectively improved in the CFJ group, especially the acetic acid and butyric acid levels. Intestinal flora analysis showed that DSS could enrich harmful bacteria such as Alistipes and Oribacterium and that CFJ could increase the abundance of beneficial bacteria (Parasutterella, Bacteroides, Roseburia and Blautia). SIgA in the colon was positively correlated with Lachnoclostridium, Blautia, Lachnospiraceae_UCG-004, Prevotellaceae_NK3B31_group and other beneficial bacteria. The results showed that DSS group rats had immunity and signalling pathway disorders and that CFJ could regulate immune disorders, mainly by regulating the expression of IgA pathway components. Taken together, our results demonstrated that CFJ could regulate changes in the gut microbiota, improve the expression of immune protein-related genes, further regulate intestinal mucosal immune function and maintain intestinal mucosal barrier homeostasis.

Antioxidant and Anti-inflammatory Properties of Resveratrol in Diabetic Nephropathy: A Systematic Review and Meta-analysis of Animal Studies

Background: Accumulated experimental evidence suggests that resveratrol may have an effect on diabetic nephropathy by inhibiting inflammation and decreasing oxidative stress. However, the credibility of the evidence for this practice is unclear. Thus, we aimed to perform a systematic review and meta-analysis of animal studies to evaluate the antioxidant and anti-inflammatory properties of resveratrol when used in the treatment of diabetic nephropathy.

Methods: Electronic bibliographic databases including PubMed, EMBASE, and Web of Science were searched for relevant studies. The methodological quality of animal studies was assessed based on the SYstematic Review Center for Laboratory animal Experimentation Risk of Bias (SYRCLE’s RoB) tool. A meta-analysis was performed based on the Cochrane Handbook for Systematic Reviews of Interventions by using RevMan 5.4 software. This study was registered within International Prospective Register of Systematic Reviews (PROSPERO) as number CRD42021293784.

Results: Thirty-six qualified studies involving 726 animals were included. There was a significant association of resveratrol with the levels of blood glucose (BG), serum creatinine (Scr), blood urea nitrogen (BUN), catalase (CAT), superoxide dismutase (SOD), malondialdehyde (MDA), glutathione (GSH), glutathione peroxidase (GPx), and interleukin-1β (IL-1β). Nevertheless, resveratrol treatment did not effectively decrease the levels of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). In addition, more remarkable antioxidant and hypoglycemic effects were observed in type 2 diabetic nephropathy rather than in type 1 diabetic nephropathy based on subgroup analysis.

Conclusion: In this meta-analysis, resveratrol can exert its antioxidant activities by reducing the levels of MDA and recovering the activities of SOD, CAT, GSH, and GPx. With regard to pro-inflammatory cytokines, resveratrol had a positive effect on the reduction of IL-1β. However, the analysis indicated that resveratrol had no effect on IL-6 and TNF-α levels, probably because of the methodological quality of the studies and their heterogeneity. Current evidence supports the antioxidant and anti-inflammatory properties of resveratrol, but its relationship with the levels of some inflammatory cytokines such as IL-6 and TNF-α in animals with diabetic nephropathy needs further elucidation.

Chemistry, Biosynthesis and Pharmacology of Sarsasapogenin: A Potential Natural Steroid Molecule for New Drug Design, Development and Therapy

Sarsasapogenin is a natural steroidal sapogenin molecule obtained mainly from Anemarrhena asphodeloides Bunge. Among the various phytosteroids present, sarsasapogenin has emerged as a promising molecule due to the fact of its diverse pharmacological activities. In this review, the chemistry, biosynthesis and pharmacological potentials of sarsasapogenin are summarised. Between 1996 and the present, the relevant literature regarding sarsasapogenin was obtained from scientific databases including PubMed, ScienceDirect, Scopus, and Google Scholar. Overall, sarsasapogenin is a potent molecule with anti-inflammatory, anticancer, antidiabetic, anti-osteoclastogenic and neuroprotective activities. It is also a potential molecule in the treatment for precocious puberty. This review also discusses the metabolism, pharmacokinetics and possible structural modifications as well as obstacles and opportunities for sarsasapogenin to become a drug molecule in the near future. More comprehensive preclinical studies, clinical trials, drug delivery, formulations of effective doses in pharmacokinetics studies, evaluation of adverse effects and potential synergistic effects with other drugs need to be thoroughly investigated to make sarsasapogenin a potential molecule for future drug development.

Polyphenol Rich Forsythia suspensa Extract Alleviates DSS-Induced Ulcerative Colitis in Mice through the Nrf2-NLRP3 Pathway

This study systematically evaluated the effect of Forsythia suspensa extract on dextran sodium sulfate (DSS)-induced ulcerative colitis (UC) and determined its mechanism of action. The results showed that Forsythia suspensa extract significantly inhibited DSS-induced UC in mice. In vivo mechanistic studies revealed that Forsythia suspensa extract relieved the symptoms of colitis by enhancing antioxidant activity and inhibiting pyroptosis. Further in vitro experiments on the mechanism of Forsythia suspensa showed that it reduced the level of reactive oxygen species (ROS) in J774A.1 cells. We found that Forsythia suspensa extract enhanced cellular antioxidation activity and inhibited pyroptosis. After silencing NLRP3, it was found to play an important role in pyroptosis. In addition, after Nrf2 was silenced, the inhibitory effect of Forsythia suspensa extract on cell pyroptosis was eliminated, indicating an interaction between Nrf2 and NLRP3. Metabonomics revealed that Forsythia suspensa extract significantly improved metabolic function in colitis mice by reversing the abnormal changes in the levels of 9 metabolites. The main metabolic pathways involved were glutathione metabolism, aminoacyl-tRNA biosynthesis and linoleic acid metabolism. In conclusion, we found that Forsythia suspensa extract significantly alleviated DSS-induced UC injury through the Nrf2-NLRP3 pathway and relieved metabolic dysfunction.

N6-methyladenosine modification of TGM2 mRNA contributes to the inhibitory activity of sarsasapogenin in rheumatoid arthritis fibroblast-like synoviocytes

BACKGROUND

Developing alternative targets and drugs for rheumatoid arthritis (RA) treatment is currently an urgent issue. The relationship between TGM2 and the abnormal immune microenvironment in synovium tissues, as well as the specific role of TGM2 in RA are yet to be elucidated. Sarsasapogenin (Sar) is a sapogenin extracted from the Chinese medical herb Anemarrhena asphodeloides Bunge. and served as a representative anti-inflammatory drug capable of ameliorating inflammatory responses in several human diseases. However, the therapeutic effect of Sar on RA remains unknown.

PURPOSE

This investigation aims to elucidate the role of TGM2 in RA and investigate whether Sar is a candidate drug to target TGM2 of fibroblast-like synoviocytes (FLS).

METHODS

Bioinformatics analyses were applied for elucidating the role of N(6)-methyladenine (m6A) RNA methylation in RA and identifying the specific target regulated by m6A methylation in RA-FLS. Methylated RNA immunoprecipitation, CCK8 assay, Edu assay, flow cytometry, RT-qPCR and Western blot were utilized to investigate the function of Sar and TGM2 in RA-FLS.

RESULTS

Bioinformatics analyses emphasized the importance of m6A RNA methylation in RA and identified an m6A methylation-mediated gene TGM2. Interestingly, both m6A RNA methylation and TGM2 expression in RA synovium tissues correlated with activated immuno-inflammatory phenotype and associated with clinical characteristics and therapy response of RA patients. TGM2 served as a promoter of RA-FLS proliferation by inducing DNA replication and cell cycle transition and inhibiting apoptosis through activating NF-κB signaling. Intriguingly, Sar could impair m6A methylation of TGM2 mRNA and downregulate TGM2 expression. Downregulated TGM2 contributed to the suppressive role of Sar in DNA replication and the stimulatory role of Sar in cell cycle arrest and apoptosis of RA-FLS. Mechanically, Sar inhibited the expression of key regulators in DNA replication, cell cycle, and apoptosis by impairing NF-κB signaling, thus abolishing FLS proliferation to ameliorate RA progression.

CONCLUSIONS

This cross-validated work based on three independent datasets is detailedly delineated using cell lines and clinical samples, recognizing that TGM2 can be an attractive target and Sar might be a novel anti-RA drug.