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OBJECTIVE To study the improvement effect of total flavonoids from Rosa multiflora root on vascular injury in rheumatoid arthritis （RA） model rats and its potential mechanism. METHODS Female Wistar rats were randomly divided into normal control group， model group， aspirin group （positive control， 30 mg/kg）， low-dose and high-dose groups of total flavonoids from R. multiflora root （4.15， 8.30 g/kg， by crude drug）， with 10 rats in each group. Except for the normal control group， the RA model was induced in other groups by collagen induction and high-fat diet. After 14 days of modeling， they were given corresponding drug solution/0.5% sodium carboxymethyl cellulose solution intragastrically， once a day， for 36 consecutive days. The total body score， arthritis index （AI） and swollen joint count （SJC） of the rats were evaluated regularly. After the last medication， serum levels of interleukin-6 （IL-6）， intercellular adhesion molecule-1 （ICAM-1） and vascular cell adhesion molecule- 1 （VCAM-1） were determined. The pathological morphological changes in the vascular tissue of thoracic aorta were observed； the protein expression of Toll-like receptor 4 （TLR4） and the protein phosphorylation levels of Janus kinase 2 （JAK2） and signal transduction and activator of transcription 3 （STAT3） in vascular tissue of thoracic aorta were measured. RESULTS Compared with the normal control group， serum levels of IL-6， ICAM-1 and VCAM-1， protein expression of TLR4， and the protein phosphorylation levels of JAK2 and STAT3 in vascular tissue of thoracic aorta were increased significantly in model group （P＜ 0.01）. The atherosclerotic plaque （atheroma）， cholesterol crystal， lymphocyte infiltration and a small number of unbroken foam cell aggregation could be seen in the vascular tissue of thoracic aorta. Compared with the model group， total body score （except for the low-dose group）， AI and SJC were decreased significantly in groups of total flavonoids from R. multiflora root on the 28th day （P＜0.05 or P＜0.01）； total body score，AI and SJC were decreased significantly in low-dose group of total flavonoids from R. multiflora root on the 49th day （P＜0.05 or P＜0.01）； the other quantitative indicators in serum and vascular tissue were significantly reversed in groups of total flavonoids from R. multiflora root （P＜0.05 or P＜0.01）， and pathological damage of vascular tissue was significantly relieved. CONCLUSIONS Total flavonoids from R. multiflora root can significantly improve vascular injury in RA model rats， and its mechanism may be related to reducing the protein expression of TLR4 in vascular tissue and inhibiting the activation of IL-6/JAK2/ STAT3 signaling pathway.
RESUMEN
The goal of this study was to investigate the regulatory effect of angiotensin converting enzyme 2 (ACE2) on cellular inflammation caused by avian infectious bronchitis virus (IBV) and the underlying mechanism of such effect. Vero and DF-1 cells were used as test target to be exposed to recombinant IBV virus (IBV-3ab-Luc). Four different groups were tested: the control group, the infection group[IBV-3ab-Luc, MOI (multiplicity of infection)=1], the ACE2 overexpression group[IBV-3ab Luc+pcDNA3.1(+)-ACE2], and the ACE2-depleted group (IBV-3ab-Luc+siRNA-ACE2). After the cells in the infection group started to show cytopathic indicators, the overall protein and RNA in cell of each group were extracted. real-time quantitative polymerase chain reaction (RT-qPCR) was used to determine the mRNA expression level of the IBV nucleoprotein (IBV-N), glycoprotein 130 (gp130) and cellular interleukin-6 (IL-6). Enzyme linked immunosorbent assay (ELISA) was used to determine the level of IL-6 in cell supernatant. Western blotting was performed to determine the level of ACE2 phosphorylation of janus kinase 2 (JAK2) and signal transducer and activator of transcription 3 (STAT3). We found that ACE2 was successfully overexpressed and depleted in both Vero and DF-1 cells. Secondly, cytopathic indicators were observed in infected Vero cells including rounding, detaching, clumping, and formation of syncytia. These indicators were alleviated in ACE2 overexpression group but exacerbated when ACE2 was depleted. Thirdly, in the infection group, capering with the control group, the expression level of IBV-N, gp130, IL-6 mRNA and increased significantly (P < 0.05), the IL-6 level was significant or extremely significant elevated in cell supernatant (P < 0.05 or P < 0.01); the expression of ACE2 decreased significantly (P < 0.05); protein phosphorylation level of JAK2 and STAT3 increased significantly (P < 0.05). Fourthly, comparing with the infected group, the level of IBV-N mRNA expression in the ACE2 overexpression group had no notable change (P > 0.05), but the expression of gp130 mRNA, IL-6 level and expression of mRNA were elevated (P < 0.05) and the protein phosphorylation level of JAK2 and STAT3 decreased significantly (P < 0.05). In the ACE2-depleted group, there was no notable change in IBV-N (P > 0.05), but the IL-6 level and expression of mRNA increased significantly (P < 0.05) and the phosphorylation level of JAK2 and STAT3 protein decreased slightly (P > 0.05). The results demonstrated for the first time that ACE2 did not affect the replication of IBV in DF-1 cell, but it did contribute to the prevention of the activation of the IL-6/JAK2/STAT3 signaling pathway, resulting in an alleviation of IBV-induced cellular inflammation in Vero and DF-1 cells.