In vitro and in vivo anti-inflammatory and anti-arthritic effect of Tinospora cordifolia via modulation of JAK/STAT pathway.

BACKGROUND: Rheumatoid arthritis (RA) is a chronic inflammatory disorder causing cartilage and joint degeneration. In spite of the availability of several robust drugs like biologics, most of the patients are unresponsive, and reports of severe adverse effects following long-term use are also there. Subsequently the use of natural plant-based products in RA therapy is broadening over the years. Tinospora cordifolia is a widely used medicinal plant in Ayurveda against various inflammatory disorders including RA. However, there is very limited knowledge regarding the actual molecular events responsible for its therapeutic effect, and this has limited its acceptance among the professionals. PURPOSE: To explore the anti-inflammatory and anti-arthritic effect of hydro-alcoholic extract from Tinospora cordifolia. METHODS: The rich polyphenol nature of the extract was elucidated using HPLC. LPS-stimulated murine macrophage cell line RAW 264.7 was used for in vitro studies, and collagen-induced arthritis (CIA) model was used for in vivo studies. RESULTS: The polyphenols in TCE were identified using HPLC. TCE effectively downregulated the level of pro-inflammatory mediators (IL-6, TNF-α, PGE2, and NO) in LPS-stimulated RAW 264.7 cells. Subsequently the upregulated expression of COX-2 and iNOS following LPS stimulation were also downregulated by TCE. Furthermore, TCE targeted the upstream kinases of the JAK/STAT pathway, a crucial inflammatory pathway. The expression of VEGF, a key angiogenic factor as well as an inflammatory mediator was also decreased following pre-treatment with TCE. The anti-arthritic effect of TCE (150 mg/kg) was evaluated in the CIA model as well. From the results of histopathology, oral administration of TCE was found to be effective in reducing the clinical symptoms of arthritis including paw edema, erythema, and hyperplasia. In vivo results validated the in vitro results and there was a significant reduction in serum level of pro-inflammatory cytokines and mediators (IL-6, TNF-α, IL-17, NO, and PGE2). The phosphorylation of STAT3 and the expression of VEGF were also downregulated following TCE treatment. CONCLUSION: Our study provided a detailed insight into the molecular events associated with anti-inflammatory and anti-arthritic effect of Tinospora cordifolia.

Vanillic acid mitigates hyperinsulinemia induced ER stress mediated altered calcium homeostasis, MAMs distortion and surplus lipogenesis in HepG2 cells.

Hyperinsulinemia (HI) induced insulin resistance (IR) and associated pathologies are the burning and unsolvable issues in diabetes treatment. The cellular, molecular and biochemical events associated with HI are not yet elucidated. Similarly, no focused research on designing therapeutic strategies with natural products for attenuation of HI are seen in literature. Keeping this in mind we planned the present study to evaluate the alterations occurring at ER/Ca2+ homeostasis/mitochondria associated endoplasmic reticulum membranes (MAMs) in HepG2 cells during HI and to evaluate the possible beneficial effect of vanillic acid (VA) to mitigate the complications. An in vitro model of HI was established by treating HepG2 cells with human insulin (1 µM) for 24 h. Then, ER stress, Ca2+ homeostasis, MAMs, IR and hepatic lipogenesis were studied at protein level. Various proteins critical to ER, Ca2+ homeostasis and MAMs such as p-IRE-1α, ATF6, p-PERK, p-eIF2α, CHOP, XBP1, p-CAMKII, InsP3R, SERCA, JNK, GRP78, VDAC, Cyp D, GRP75, MFN2, PTEN and mTORC were studied and found altered significantly causing ER stress, defect in Ca2+ movements and distortion of MAMs. The decreased expression of IRS2 and an unaltered expression of IRS1 confirmed the development of selective insulin resistance in hepatocytes during HI and this was the crucial factor for the progression of the hepatic lipid accumulation. We found simultaneous treatment of VA is beneficial up to a certain extent to protect HepG2 cells from the adverse effect of HI via its antioxidant, antilipogenic, mitochondrial and ER protection properties.

Endoplasmic reticulum stress: A master regulator of metabolic syndrome.

Endoplasmic reticulum (ER) stress, a change in the ER homeostasis, leads to initiation of the unfolded protein response (UPR). The primary functions of the UPR are to restore the ER's physiological activity and coordinate the apoptotic and adaptive responses. Pathophysiological conditions that augment ER stress include hypoxia, misfolded and/or mutated protein accumulation, and high glucose. Prolonged ER stress is a critical factor in the pathogenesis of metabolic syndrome including type 2 diabetes mellitus, cardiovascular diseases, atherosclerosis, obesity, and fatty liver disease. UPR is a complex homeostatic pathway between newly synthesized proteins and their maturation, although the regulatory mechanisms contributing to the UPR and the possible therapeutic strategies are yet to be clarified. Therefore, a comprehensive understanding of the underlying molecular mechanisms is necessary to develop therapeutic interventions targeting ER stress response. In this review, we discuss the role of ER stress and UPR signaling in the pathogenesis of metabolic syndrome, highlighting the main functions of UPR components. We have emphasized the use of novel small molecular chemical chaperones, considered as modulators of ER stress. The initial studies with these chemical chaperones are promising, but detailed studies are required to define their efficacy and adverse effects during therapeutic use in humans.