Objective:

2

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

Methods:

2

Tumor necrosis factor (TNF)-α-induced fibroblast-like synoviocytes (FLS) was exposed to additional isorhamnetin (10

20 and 40 μmol/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-1β

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:

2

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-1β 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-1β (

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-1β

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:

2

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.