The emerging role of irisin in experimentally induced arthritis: a recent update involving HMGB1/MCP1/Chitotriosidase I-mediated necroptosis.

OBJECTIVES: Necroptosis is a tightly adjusted inflammatory necrotizing cell death signaling pathway that participates in pathogenesis of discrete diseases as rheumatoid arthritis (RA). Irisin is a myokine with immuno-modulatory effect. Evaluation of irisin efficiency as a novel therapeutic agent in experimentally induced RA via modulating immuno-inflammatory, necroptotic molecular and biochemical signaling pathways. METHODS: RA was induced in 30 female Wister albino rats by a single subcutaneous injection of collagen-II with incomplete Freund's adjuvant (CII-IFA) followed by booster immunization dose 10 days later. After 14 days of the injection, arthritis chronic phase was precipitated. 15 rats were treated by S.C irisin injection daily for 4 weeks. Joint tissue homogenate RIPK-3, MLKL, HMGB1, MCP1, IL-6, CHIT1, MDA, and PN levels were assessed calorimetrically. However, TNF-α mRNA expression level was evaluated by the qrt-PCR technique. RESULTS: The results showed that irisin significantly decreases the level of all assessed biochemical parameters, except MDA, which was significantly increased in comparison with the correspondent values in the arthritic group with no treatment (ttt). CONCLUSIONS: Irisin exhibits therapeutic anti-inflammatory and antioxidant effects via modulating immuno-inflammatory, necroptotic molecular, and biochemical signaling pathways in experimentally induced RA in rats. ABBREVIATIONS: RA: rheumatoid arthritis; RIPK3: receptor-interacting protein kinase 1; MLKL: mixed lineage kinase domain-like protein; HMGB1: High-mobility group protein box 1; MCP1: Monocyte chemoattractant protein 1; IL-6: Interleukin 6; CHIT1: Chitotriosidase; MDA: Malondialdehyde; PN: Peroxynitrite; TNF-α: Tumor Necrosis Factor; qrt-PCR: quantitative real-time reverse transcription PCR; CII-IFA: collagen-II with incomplete Freund's adjuvant; ttt: treatmentNote: TNF-α gene (NCBI GenBank Nucleotide accession # NM_012675.3); The housekeeping gene GAPDH (NCBI GenBank Nucleotide accession # NM_017008.4).

Troxerutin downregulates C/EBP-ß gene expression via modulating the IFNγ-ERK1/2 signaling pathway to ameliorate rotenone-induced retinal neurodegeneration.

Troxerutin, a natural flavonoid guards against oxidative stress and apoptosis with a high capability of passing through the blood-brain barrier. Our aim was to investigate the role of troxerutin in experimentally induced retinal neurodegeneration by modulating the interferon-gamma (IFNγ)-extracellular signal-regulated kinases 1/2 (ERK1/2)-CCAAT enhancer-binding protein ß (C/EBP-ß) signaling pathway. Three groups of rats (10 each group) were included. Group I (control group), group II (rotenone treated group): the rats were injected subcutaneously with a single rotenone dosage of 3 mg/kg repeated every 48 hours for 60 days to trigger retinal neurodegeneration. Group III (troxerutin-treated group): rats received troxerutin (150 mg/kg/day) by oral gavage 1 hour before rotenone administration. A real-time polymerase chain reaction technique was applied to measure messenger RNA (mRNA) levels of retinal C/EBP-ß. Enzyme-linked immunosorbent assay technique was utilized to assay tumor necrosis factor-α (TNF-α), IFNγ, and ERK1/2 levels. Finally, reactive oxygen species (ROS), as well as carbonylated protein (CP) levels, were assessed spectrophotometrically. Improved retinal neurodegeneration by downregulation of C/EBP-ß mRNA gene expression, also caused a significant reduction of TNF-α, IFNγ, ERK1/2 as well as ROS and CP levels compared with the diseased group. These findings could hold promise for the usage of troxerutin as a protective agent against rotenone-induced retinal neurodegeneration.