Tanshinone IIA prevents LPS-induced inflammatory responses in mice via inactivation of succinate dehydrogenase in macrophages.

Metabolic reprogramming is associated with NLRP3 inflammasome activation in activated macrophages, contributing to inflammatory responses. Tanshinone IIA (Tan-IIA) is a major constituent from Salvia miltiorrhiza Bunge, which exhibits anti-inflammatory activity. In this study, we investigated the effects of Tan-IIA on inflammation in macrophages in focus on its regulation of metabolism and redox state. In lipopolysaccharides (LPS)-stimulated mouse bone marrow-derived macrophages (BMDMs), Tan-IIA (10 µM) significantly decreased succinate-boosted IL-1ß and IL-6 production, accompanied by upregulation of IL-1RA and IL-10 release via inhibiting succinate dehydrogenase (SDH). Tan-IIA concentration dependently inhibited SDH activity with an estimated IC50 of 4.47 µM in LPS-activated BMDMs. Tan-IIA decreased succinate accumulation, suppressed mitochondrial reactive oxygen species production, thus preventing hypoxia-inducible factor-1α (HIF-1α) induction. Consequently, Tan-IIA reduced glycolysis and protected the activity of Sirtuin2 (Sirt2), an NAD+-dependent protein deacetylase, by raising the ratio of NAD+/NADH in activated macrophages. The acetylation of α-tubulin was required for the assembly of NLRP3 inflammasome; Tan-IIA increased the binding of Sirt2 to α-tubulin, and thus reduced the acetylation of α-tubulin, thus impairing this process. Sirt2 knockdown or application of Sirt2 inhibitor AGK-2 (10 µM) neutralized the effects of Tan-IIA, suggesting that Tan-IIA inactivated NLRP3 inflammasome in a manner dependent on Sirt2 regulation. The anti-inflammatory effects of Tan-IIA were observed in mice subjected to LPS challenge: pre-administration of Tan-IIA (20 mg/kg, ip) significantly attenuated LPS-induced acute inflammatory responses, characterized by elevated IL-1ß but reduced IL-10 levels in serum. The peritoneal macrophages isolated from the mice displayed similar metabolic regulation. In conclusion, Tan-IIA reduces HIF-1α induction via SDH inactivation, and preserves Sirt2 activity via downregulation of glycolysis, contributing to suppression of NLRP3 inflammasome activation. This study provides a new insight into the anti-inflammatory action of Tan-IIA from the respect of metabolic and redox regulation.

Corydalis saxicola Bunting total alkaloids attenuate paclitaxel-induced peripheral neuropathy through PKCε/p38 MAPK/TRPV1 signaling pathway.

BACKGROUND: Corydalis saxicola Bunting, affiliated with the Papaveraceae Juss., has been proven to work well in anti-inflammation, hemostasis, and analgesia. This study was designed to observe the effect and potential mechanism of Corydalis saxicola Bunting total alkaloids (CSBTA) on paclitaxel-induced peripheral neuropathy (PIPN). MATERIALS AND METHODS: Rats were injected 2 mg/kg paclitaxel 4 times and administrated with 30 or 120 mg/kg CSBTA. Mechanical and thermal allodynia and hyperalgesia were tested. After 40 days, serum was collected to detect PGE2, TNF-α, and IL-1ß by ELISA. The L4-L6 segment spinal cord, DRG, and plantar skin were harvested, and Western-blot or RT-qPCR analyzed protein and gene levels of pro-inflammatory cytokines, p38 MAPK, PKCε, and TRPV1. The PIPN cell model was established with paclitaxel (300 nM, 5 d) in primary DRG neurons. We examined the effect of CSBTA (25 µg/ml or 50 µg/ml) by measuring the mRNA levels in PGE2, TNF-α and CGRP, and the protein expression on the PKCε/p38 MAPK/TRPV1 signaling pathway in the PIPN cell model. RESULTS: The results showed that CSBTA effectively ameliorated allodynia and hyperalgesia, and regulated cytokines' contents (PGE2, TNF-α, and IL-1ß) and neuropeptides (CGRP and SP) in different tissues in vivo. In addition, CSBTA significantly decreased cytokine gene levels of DRG neurons (PGE2, TNF-α, and CGRP) and the protein expressions of PKCε/p38 MAPK/TRPV1 signaling pathway in vivo and in vitro. CONCLUSION: Therefore, CSBTA has a perspective therapeutic effect on the treatment of paclitaxel-induced peripheral neuropathy.

Berberine Ameliorates Diabetic Neuropathy: TRPV1 Modulation by PKC Pathway.

In recent years, berberine has increasingly become a topic of research as a treatment for diabetes due to its repair function, which recovers damaged pancreatic ß cells. However, it is the complications of diabetes that seriously affect patients' life quality and longevity, among which diabetic neuropathy and the consequent acute pain are the most common. In this study, we established STZ-induced diabetic models to observe whether berberine, a main constitute of Coptis chinensis Franch which has shown good hypoglycemic effects, could relieve diabetes-induced pain and explored its possible mechanism in rats and mice. Behavior assays showed increasing mechanical allodynia and thermal hyperalgesia thresholds by the Von Frey test and tail flick test during the treatment of berberine. It was found that the administration of berberine (20, 60 mg/kg; 30, 90 mg/kg) suppressed the expression of PKCε and TRPV1 which could be activated by hyperglycemia-induced inflammatory reaction. Our results also presented its capability to reduce the over expression of TNF-[Formula: see text] in diabetic rats and mice. TNF-[Formula: see text] is an inflammatory cytokine, which is closely related to diabetic peripheral neuropathy (DPN). Consequently, we supposed that berberine exerts its therapeutic effects in part by suppressing the inflammatory process and blocking the PKC pathway to inhibit TRPV1 activation, which damages neurons and causes diabetic pain.

Species Comparison of Pre-systemic Bioactivation of Vicagrel, a New Acetate Derivative of Clopidogrel.

Previously we have found vicagrel, a new acetate derivative of clopidogrel, underwent hydrolysis to 2-oxo-clopidogrel and subsequent conversions to its pharmacological active metabolite (AM) and inactive carboxylic acid metabolite (CAM). This study demonstrated the interspecies differences of the vicagrel bioactivation by comparing the critical vicagrel metabolites formation in rats, dogs and human. The pharmacokinetic studies with rats and dogs were conducted after intragastric administration of vicagrel, followed by in vitro metabolism investigation in venous system, intestinal/hepatic microsomes from rats, dogs and human. An obvious disparity was observed in system exposure to AM (99.0 vs. 635.1 µg⋅h/L, p < 0.05) and CAM (10119 vs. 2634 µg⋅h/L, p < 0.05) in rats and dogs. It was shown that the cleavage of vicagrel was almost completed in intestine with great different clearance (53.28 vs. 3.643 L⋅h-1⋅kg-1, p < 0.05) in rats and dogs. With no further hydrolysis to CAM, the greatest clearance of AM (3.26 mL⋅h-1⋅kg-1) was found in dog intestine. In rat plasma, 2-oxo-clopidogrel was much more extensively hydrolyzed to CAM than in dog and human. Albeit similar hydrolysis clearance and AM production was observed among hepatic microsomes of the three species, the production velocity of CAM ranked highest in dogs (7.55 pmol/min/mg protein). Therefore, the unconformity of AM and CAM exposure cross species mainly came from the metabolism of 2-oxo-clopidogrel associated largely with tissue specificity and interspecies differences of esterases. In human, the pharmacokinetics of vicagrel might be more optimistic due to less inactivation hydrolysis before reaching liver.