Isorhamnetin Downregulates MMP2 and MMP9 to Inhibit Development of Rheumatoid Arthritis through SRC/ERK/CREB Pathway

OBJECTIVE

To investigate the effect of isorhamnetin on the pathology of rheumatoid arthritis (RA).

METHODS

Tumor necrosis factor (TNF)- α -induced fibroblast-like synoviocytes (FLS) was exposed to additional isorhamnetin (10, 20 and 40 µ mol/L). Overexpression vectors for matrix metalloproteinase-2 (MMP2) or MMP9 or SRC were transfected to explore their roles in isorhamnetin-mediated RA-FLS function. RA-FLS viability, migration, and invasion were evaluated. Moreover, a collagen-induced arthritis (CIA) rat model was established. Rats were randomly divided to sham, CIA, low-, medium-, and high-dosage groups using a random number table (n=5 in each group) and administed with normal saline or additional isorhamnetin [2, 10, and 20 mg/(kg·day)] for 4 weeks, respectively. Arthritis index was calculated and synovial tissue inflammation was determined in CIA rats. The levels of MMP2, MMP9, TNF-α, interleukin-6 (IL-6), and IL-1 β, as well as the phosphorylation levels of SRC, extracellular regulated kinase (ERK), and cyclic adenosine monophosphate response element-binding (CREB), were detected in RA-FLS and synovial tissue. Molecular docking was also used to analyze the binding of isorhamnetin to SRC.

RESULTS

In in vitro studies, isorhamnetin inhibited RA-FLS viability, migration and invasion (P<0.05). Isorhamnetin downregulated the levels of MMP2, MMP9, TNF-α, IL-6, and IL-1 β in RA-FLS (P<0.05). The overexpression of either MMP2 or MMP9 reversed isorhamnetin-inhibited RA-FLS migration and invasion, as well as the levels of TNF-α, IL-6, and IL-1 β (P<0.05). Furthermore, isorhamnetin bound to SRC and reduced the phosphorylation of SRC, ERK, and CREB (P<0.05). SRC overexpression reversed the inhibitory effect of isorhamnetin on RA-FLS viability, migration and invasion, as well as the negative regulation of MMP2 and MMP9 (P<0.05). In in vivo studies, isorhamnetin decreased arthritis index scores (P<0.05) and alleviated synovial inflammation. Isorhamnetin reduced the levels of MMP2, MMP9, TNF-α, IL-6, and IL-1 β, as well as the phosphorylation of SRC, ERK, and CREB in synovial tissue (P<0.05). Notably, the inhibitory effect of isorhamnetin was more pronounced at higher concentrations (P<0.05).

CONCLUSION

Isorhamnetin exhibited anti-RA effects through modulating SRC/ERK/CREB and MMP2/MMP9 signaling pathways, suggesting that isorhamnetin may be a potential therapeutic agent for RA.

[Research progress on Rhododendron molle in treatment of rheumatoid arthritis]

Rheumatoid arthritis(RA), as a chronic autoimmune disease, has a high incidence and disability rate, causing significant suffering to patients. Due to its complex pathogenesis, it has not been fully elucidated to date, and its treatment remains a challenging problem in the medical field. Although western medicine treatment options have certain efficacy, they require prolonged use and are expensive. Additionally, they carry risks of multiple infections and adverse reactions like malignancies. The Chinese herbal medicine Rhododendron molle is commonly used in folk medicine for its properties of dispelling wind, removing dampness, calming nerves, and alleviating pain in the treatment of diseases like rheumatic bone diseases. In recent years, modern clinical and pharmacological studies have shown that the diterpenoids in R. molle are effective components, exhibiting immune-regulatory, anti-inflammatory, and analgesic effects. This makes it a promising candidate for treating RA with a broad range of potential applications. However, R. molle has certain toxic properties that hinder its clinical application and lead to the wastage of its resources. This study reviewed recent research progress on the mechanism of R. molle in preventing and treating RA, focusing on its chemical components, anti-inflammatory and analgesic properties and summarized the adverse reactions associated with R. molle, aiming to offer new ideas for finding natural remedies for RA and methods to reduce toxicity while enhancing the effectiveness of R. molle. The study seeks to clarify the safety and efficacy of R. molle and its extracts, providing a theoretical basis for its application prospects and further promoting the development and utilization of R. molle resources.

Cloning and analysing of 5' flanking region of Xenopus organizer gene noggin

Xenopus organizer specific gene Noggin possesses nearly all the characteristic properties of the action of organizer to specify the embryonic body axis. To analyze how the maternal inherited factors control its expression pattern, we cloned the 5' regulatory region of noggin gene. The 1.5 kb upstream sequence could direct reporter gene to express in vivo and data from deletion analysis indicated that a 229 base pair fragment is essential for activating noggin expression. We further demonstrated that the response elements within this regulatory region were indeed under the control of growth factor activin and Wnt signaling pathway components.

[Tissue specific differentiation of dorsal mesoderm in Xenopus mid-gastrula embryos]

Genes involved in differentiation of notochord or muscle are expressed in specific regions of the involuted dorsal mesoderm in mid-gastrula Xenopus embryo. The presumptive notochord or the presomitic mesoderm have been cultured either in isolation or recombination to investigate whether these tissues have been determined. Cell differentiation was checked by specific markers of notochord (Shh) or muscle cell (desmin, myosin). The results show that the presumptive notochord can differentiate into vacuolated notochord with a weak expression of Shh, while the presomitic mesoderm differentiate into muscle cells with a normal expression of desmin and myosin in vitro. The same result was obtained when the two tissues have been cocultured. These data suggest that the cell fate of the involuted dorsal mesoderm in mid-gastrula has been determined, cells can differentiate according to their fates without further signals from the adjacent tissues, but no functional structures can be formed by these tissues in vitro.