[Sidaxue, a traditional Guizhou Miao herbal medicine formula, reduces necroptosis and synovial vascular proliferation in rats with collagen-induced arthritis by inhibiting the RIPK1/RIPK3/MLKL pathway]

OBJECTIVE

To explore the inhibitory effect of Sidaxue (SX), a traditional Guizhou Miao herbal medicine formula, on necrotic apoptosis and synovial angiogenesis in rats with collagen-induced arthritis (CIA) and the role of the RIPK1/RIPK3/MLKL pathway in mediating this effect.

METHODS

Forty-two SD rats were randomized into 6 groups (n=7), including a normal control group, a CIA model group, 3 SX treatment groups at low (10 g/kg), moderate (20 g/kg) and high (40 g/kg) doses, and a GTW treatment group. CIA rat models were established by subcutaneous injections of bovine type II collagen, and the treatments were administered daily by gavage for 21 days. The rats were observed for swelling of the hind limb joints, which was rated using the arthritis index (AI) score on a weekly basis. Serum levels of TNF-α, IL-1β and IL-17 in the rats were detected using ELISA, and the pathological changes in the synovium were observed with HE staining. Real-time PCR was performed to detect the mRNA expression levels of VEGF, MMP-9, Ang-1, RIPK1, RIPK3, and caspase-8 in the synovial tissues, and the protein expressions of VEGF, MMP9, Ang-1, Stat-3, RIPK1, RIPK3, MLKLl, p-MLKL and caspase-8 were detected using Western blotting.

RESULTS

Compared with those in CIA model group, the rats receiving treatment with GTW and SX showed milder swelling of the hind limb joints with significantly lower AI scores (P < 0.05). In CIA model group, a large number of inflammatory cells were observed in the synovium with obvious damages of the tissue structure. In the drug treatment groups, inflammatory cell infiltration, synovial angiogenesis and synovial hyperplasia were alleviated, and the therapeutic effects were obviously enhanced as SX dose increased. Compared with those in the model group, the rats treated with GTW and high-dose SX showed significantly decreased serum levels of IL-1β, IL-17 and TNF-α (P < 0.05), lower mRNA and protein expressions of RIPK1, RIPK3, VEGF, Ang-1, and MMP9 (P < 0.05), higher expressions of caspase-8 (P < 0.01), and obviously lowered expression of Stat-3 protein and phosphorylation level of MLKL (P < 0.05).

CONCLUSION

SX can improve synovial angiogenesis in CIA rats possibly by inhibiting the activation of RIP1/RIP3/MLKL signaling pathway and down-regulating the expression of the vascular growth factors VEGF, Ang-1, MMP9, and Stat-3.

Dual Topoisomerase I/II Inhibition-Induced Apoptosis and Necro-Apoptosis in Cancer Cells by a Novel Ciprofloxacin Derivative via RIPK1/RIPK3/MLKL Activation

Fluoroquinolones (FQs) are synthetic broad-spectrum antimicrobial agents that have been recently repurposed to anticancer candidates. Designing new derivatives of FQs with different moieties to target DNA topoisomerases could improve their anticancer efficacy. The present study aimed to synthesize a novel ciprofloxacin derivative, examine its anticancer activity against HepG2 and A549 cancer cells, and investigate the possible molecular mechanism underlying this activity by examining its ability to inhibit the topo I/II activity and to induce the apoptotic and necro-apoptotic pathways. Molecular docking, cell viability, cell migration, colony formation, cell cycle, Annexin V, lactate dehydrogenase (LDH) release, ELISA, and western blotting assays were utilized. Molecular docking results showed that this novel ciprofloxacin derivative exerted dual topo I and topo II binding and inhibition. It significantly inhibited the proliferation of A549 and HepG2 cancer cells and decreased their cell migration and colony formation abilities. In addition, it significantly increased the % of apoptotic cells, caused cell cycle arrest at G2/M phase, and elevated the LDH release levels in both cancer cells. Furthermore, it increased the expression of cleaved caspase 3, RIPK1, RIPK3, and MLKL proteins. This novel ciprofloxacin derivative exerted substantial dual inhibition of topo I/II enzyme activities, showed antiproliferative activity, suppressed the cell migration and colony formation abilities for A549 and HepG2 cancer cells and activated the apoptotic pathway. In addition, it initiated another backup deadly pathway, necro-apoptosis, through the activation of the RIPK1/RIPK3/MLKL pathway.