Tomentosin suppressed M1 polarization via increasing MERTK activation mediated by regulation of GAS6.

ETHNOPHARMACOLOGICAL RELEVANCE: Xanthium sibiricum Patrin ex Widder (X. sibiricum) are widely used traditional herbal medicines for arthritis treatment in China. Rheumatoid arthritis (RA) is characterized by progressive destructions of joints, which is accompanied by chronic, progressive inflammatory disorder. According to our previous research, tomentosin was isolated from X. sibiricum and revealed anti-inflammatory activity. However, the potential therapeutic effect of tomentosin on RA and the anti-inflammatory mechanism of tomentosin remain to be clarified. The present study lays theoretical support for X. sibiricum in RA treatment, also provides reference for further development of X. sibiricum in clinic. AIM OF THE STUDY: To investigate the effect of tomentosin in collagen-induced arthritis (CIA) mice and reveal its underlying mechanism. MATERIALS AND METHODS: In vivo, tomentosin (10, 20 and 40 mg/kg) was given to CIA mice for seven consecutive days, to evaluate its therapeutic effect and anti-inflammatory activity. In vitro, THP-1-derived macrophages were used to verify the effect of tomentosin on inflammation. Then, molecular docking and experiments in vitro was conducted to predict and explore the mechanism of tomentosin inhibiting inflammation. RESULTS: Tomentosin attenuated the severity of arthritis in CIA mice, which was evidenced by the swelling of the hind paws, arthritis scores, and pathological changes. Particularly, tomentosin effectively reduced the ratio of M1 macrophage and TNF-α levels in vitro and vivo. Then, molecular docking and experiments in vitro was carried out, indicating that tomentosin inhibited M1 polarization and TNF-α levels accompanied by the increase of MERTK and up-regulated GAS6 levels. Moreover, it has been proved that GAS6 was necessary for MERTK activation and tomentosin could up-regulate GAS6 levels effectively in transwell system. Further mechanistic studies revealed that tomentosin suppressed M1 polarization via increasing MERTK activation mediated by regulation of GAS6 in transwell system. CONCLUSION: Tomentosin relieved the severity of CIA mice by inhibiting M1 polarization. Furthermore, tomentosin suppressed M1 polarization via increasing MERTK activation mediated by regulation of GAS6.

Panax notoginseng saponins (PNS) attenuate Th17 cell differentiation in CIA mice via inhibition of nuclear PKM2-mediated STAT3 phosphorylation.

CONTEXT: Rheumatoid arthritis (RA) is an autoimmune disease with aberrant Th17 cell differentiation. Panax notoginseng (Burk.) F. H. Chen (Araliaceae) saponins (PNS) have an anti-inflammatory effect and can suppress Th17 cell differentiation. OBJECTIVE: To investigate mechanisms of PNS on Th17 cell differentiation in RA, and the role of pyruvate kinase M2 (PKM2). MATERIALS AND METHODS: Naive CD4+T cells were treated with IL-6, IL-23 and TGF-ß to induce Th17 cell differentiation. Apart from the Control group, other cells were treated with PNS (5, 10, 20 µg/mL). After the treatment, Th17 cell differentiation, PKM2 expression, and STAT3 phosphorylation were measured via flow cytometry, western blots, or immunofluorescence. PKM2-specific allosteric activator (Tepp-46, 50, 100, 150 µM) and inhibitor (SAICAR, 2, 4, 8 µM) were used to verify the mechanisms. A CIA mouse model was established and divided into control, model, and PNS (100 mg/kg) groups to assess an anti-arthritis effect, Th17 cell differentiation, and PKM2/STAT3 expression. RESULTS: PKM2 expression, dimerization, and nuclear accumulation were upregulated upon Th17 cell differentiation. PNS inhibited the Th17 cells, RORγt expression, IL-17A levels, PKM2 dimerization, and nuclear accumulation and Y705-STAT3 phosphorylation in Th17 cells. Using Tepp-46 (100 µM) and SAICAR (4 µM), we demonstrated that PNS (10 µg/mL) inhibited STAT3 phosphorylation and Th17 cell differentiation by suppressing nuclear PKM2 accumulation. In CIA mice, PNS attenuated CIA symptoms, reduced the number of splenic Th17 cells and nuclear PKM2/STAT3 signaling. DISCUSSION AND CONCLUSIONS: PNS inhibited Th17 cell differentiation through the inhibition of nuclear PKM2-mediated STAT3 phosphorylation. PNS may be useful for treating RA.

Triptolide inhibits Th17 differentiation via controlling PKM2-mediated glycolysis in rheumatoid arthritis.

CONTEXT: Rheumatoid arthritis (RA) is an autoimmune disease with the aberrant differentiation of T helper 17 (Th17) cells. Pyruvate kinase M2 (PKM2), a key enzyme of glycolysis, was associated with Th17 cell differentiation. AIM: To investigate the potential therapeutic effects of triptolide (TP) in collagen-induced arthritis (CIA) and Th17 cell differentiation, and elucidated the underlying mechanisms. METHODS: PKM2 expression and IL-17A production in peripheral blood of RA patients were detected by RT-qPCR or ELISA. Flow cytometry and ELISA were employed to assess the effect of Th17 cell differentiation by TP. PKM2 expression and other glycolysis-related factors were detected using RT-qPCR and Western Blot. PKM2 specific inhibitor Compound 3 K was used to verify the mechanisms. Male DBA/1J mice were divided into control, model, and TP (60 µg/kg) groups to assess the anti-arthritis effect, Th17 cell differentiation and PKM2 expression. RESULTS: PKM2 expression positively correlated with IL-17A production in RA patients. PKM2 expression was increased upon Th17 cell differentiation. Down-regulating PKM2 expression could strongly reduce Th17 cell differentiation. Molecular docking analysis predicted that TP targeted PKM2. TP treatment significantly reduced Th17 cell differentiation, PKM2 expression, pyruvate, and lactate production. In addition, compared with down-regulating PKM2 alone (Compound 3 K treatment), co-treatment with TP and Compound 3 K further significantly decreased PKM2-mediated glycolysis and Th17 cell differentiation. In CIA mice, TP repressed the PKM2-mediated glycolysis and attenuated joint inflammation. CONCLUSION: TP inhibited Th17 cell differentiation through the inhibition of PKM2-mediated glycolysis. We highlight a novel strategy for the use of TP in RA treatment.

Macrophage targeted triptolide micelles capable of cGAS-STING pathway inhibition for rheumatoid arthritis treatment.

The abundant M1 macrophages in the joint synovium were the main factors that exacerbate rheumatoid arthritis (RA) by secreting various types of inflammatory cytokines. Here, we note that cGAS-STING, an important pro-inflammatory pathway, was significantly up-regulated in RA, enabling it be the potential target for RA therapy. Therefore, in this work, we developed M1 macrophages targeted micelles capable of cGAS-STING pathway inhibition for the smart treatment of RA. The folic acid (FA) and lauric acid (LA) were modified on dextran to obtain an amphiphilic polymer (FDL). Then, FDL was subsequently applied to encapsulate triptolide (TP) to form FDL@TP nanomicelles. The FDL@TP could target the joint and enhance the cell uptake of TP by M1 macrophages (overexpressing folate receptor-ß), which also reduced the side effects of TP on normal tissues. In M1 macrophages, the released TP, acted as an anti-inflammatory and immunosuppressant, obviously down-regulated the expressions of cGAS and STING protein, and thus reduced the secretion of TNF-α, IL-1ß and IL-6. Importantly, compared with the same dose of free TP, FDL@TP could significantly enhance the anti-inflammatory effect. Therefore, FDL@TP nanomicelles were believed to be superior candidates for the clinical treatment of RA.

Catalpol Inhibits Tregs-to-Th17 Cell Transdifferentiation by Up-Regulating Let-7g-5p to Reduce STAT3 Protein Levels.

PURPOSE: Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease, and Th17 cells are key factors in the pathogenesis of human inflammatory conditions, such as RA. Catalpol (CAT), a component in Rehmanniae Radix (RR), has been found to regulate human immunity. However, the effects of CAT on Th17 cell differentiation and improvement of RA are not clear. MATERIALS AND METHODS: Collagen-induced arthritis (CIA) mice were constructed to detect the effects of CAT on arthritis and Th17 cells. The effect of CAT on Th17 differentiation was evaluated with let-7g-5p transfection experiments. Flow cytometry was used to detect the proportion of Th17 cells after CAT treatment. Levels of interleukin-17 and RORγt were assessed by qRT-PCR and enzyme-linked immunosorbent assay. The expression of signal transducer and activator of transcription 3 (STAT3) was determined by qRT-PCR and Western blot. RESULTS: We found that the proportion of Th17 cells was negatively associated with let-7g-5p expression in CIA mice. In in vitro experiments, CAT suppressed traditional differentiation of Th17 cells. Simultaneously, CAT significantly decreased Tregs-to-Th17 cells transdifferentiation. Our results demonstrated that CAT inhibited Tregs-to-Th17 cells transdifferentiation by up-regulating let-7g-5p and that the suppressive effect of CAT on traditional differentiation of Th17 cells is not related with let-7-5p. CONCLUSION: Our data indicate that CAT may be a potential modulator of Tregs-to-Th17 cells transdifferentiation by up-regulating let-7g-5p to reduce the expression of STAT3. These results provide new directions for research into RA treatment.