A novel mechanism for inhibiting proliferation of rheumatoid arthritis fibroblast-like synoviocytes: geniposide suppresses HIF-1α accumulation in the hypoxic microenvironment of synovium.

The excessive proliferation of fibroblast-like synoviocytes (FLSs) is a key inducement for the occurrence and development of rheumatoid arthritis (RA). Hypoxia inducible factor-α (HIF-α) accumulation is involved in the regulation of cell biological functions in the hypoxic microenvironment of synovium. This study aimed to investigate the roles of HIF-α and its level regulator prolyl hydroxylases (PHDs) in FLSs proliferation and to explore the regulatory effect of geniposide (GE). Adjuvant arthritis rats and RA-FLSs cell line MH7A were taken as the research objects. MH7A cells were incubated in a hypoxic chamber with 2% O2 for hypoxia treatment. CCK-8, FACS, EdU and Western blot assays were performed to evaluate MH7A cells proliferation. Iron assay was conducted to determine intracellular Fe2+ level. MH7A cells proliferation was significantly enhanced under hypoxia, accompanied by an increase of HIF-1α level. Decreased HIF-1α level by PX-478 inhibited MH7A cells proliferation. Furthermore, PHD2 was highly expressed in vivo and in vitro, and played a key role in modulation of HIF-1α protein level, which was confirmed by PHD2 inhibitor IOX4 and proteasome inhibitor MG132. GE treatment alleviated synovial hyperplasia in AA rats and inhibited MH7A cells proliferation with a reduction in HIF-1α level. Fe2+ acts as an enzymatic cofactor to control PHD2 activity. Iron assay showed that GE reversed the decline of Fe2+ level in MH7A cells under hypoxia. GE attenuates abnormal proliferation of RA-FLSs via inhibiting HIF-1α accumulation through enhancement of PHD2 activity.

Gan P ，Sun M ，Wu H ，Ke J ，Dong X ，Chen F ... -  《-》

Novel HIF-1α Inhibitor AMSP-30m Mitigates the Pathogenic Cellular Behaviors of Hypoxia-Stimulated Fibroblast-Like Synoviocytes and Alleviates Collagen-Induced Arthritis in Rats via Inhibiting Sonic Hedgehog Pathway.

Synovial hypoxia-inducible factor 1α (HIF-1α) is a prospective therapeutic target for rheumatoid arthritis (RA). AMSP-30 m, a novel HIF-1α inhibitor, was reported to have notable anti-arthritic effects in rats with adjuvant-induced arthritis. However, its roles in inhibiting the pathogenic behaviors of fibroblast-like synoviocytes (FLS) and the involved mechanisms remain unknown. Here, AMSP-30 m inhibited proliferation and induced apoptosis in hypoxia-induced RA FLS (MH7A cell line), as evidenced by decreased cell viability, reduced Ki67-positive cells, G0/G1 phase arrest, lowered C-myc and Cyclin D1 protein levels, emergence of apoptotic nuclear fragmentation, raised apoptosis rates, and activation of caspase 3. Furthermore, AMSP-30 m prevented hypoxia-induced increases in pro-inflammatory factor production, MMP-2 activity, migration index, migrated/invasive cells, and actin cytoskeletal rearrangement. In vivo, AMSP-30 m alleviated the severity of rat collagen-induced arthritis (CIA). Mechanically, AMSP-30 m reduced HIF-1α expression and blocked sonic hedgehog (Shh) pathway activation in hypoxia-induced MH7A cells and CIA rat synovium, as shown by declines in pathway-related proteins (Shh, Smo, and Gli-1). Particularly, the combination of Shh pathway inhibitor cyclopamine enhanced AMSP-30 m's inhibitory effects on the pathogenic behaviors of hypoxia-stimulated MH7A cells, whereas the combination of Shh pathway activator SAG canceled AMSP-30 m's therapeutic effects in vitro and in CIA rats, implying a close involvement of Shh pathway inhibition in its anti-arthritic effects. We likewise confirmed AMSP-30 m's anti-proliferative role in hypoxia-induced primary CIA FLS. Totally, AMSP-30 m suppressed hypoxia-induced proliferation, inflammation, migration, and invasion of MH7A cells and ameliorated the severity of rat CIA via inhibiting Shh signaling.

Cai L ，Meng B ，Jiang F ，Shu WH ，Wang XH ，Wang MQ ，Wu XJ ，Hu MW ，Yang YC ，Ran X ，Li R ... -  《-》

Andrographolide inhibits the migration, invasion and matrix metalloproteinase expression of rheumatoid arthritis fibroblast-like synoviocytes via inhibition of HIF-1α signaling.

Hypoxia is implicated in the pathogenesis of rheumatoid arthritis (RA), contributing to the tumor-like phenotypes of RA fibroblast-like synoviocytes (RA-FLSs). Andrographolide is the main bioactive component of Andrographis paniculata, an herbal medicine that shows therapeutic benefits in RA patients. Here, we explored the effects of andrographolide on hypoxia-induced migration and invasion of RA-FLSs. RA-FLSs were exposed to hypoxia in the presence or absence of andrographolide and cell migration and invasion were tested by Transwell assays. The expression of hypoxia-inducible factor-1 alpha (HIF-1α), matrix metalloproteinase (MMP)-1, MMP-3 and MMP-9 was measured by semi-quantitative reverse transcription polymerase chain reaction and Western blot analysis. HIF-1α DNA binding activity was assessed by electrophoretic mobility shift assay. The effects of overexpression of exogenous HIF-1α on the action of andrographolide in RA-FLSs were investigated. Andrographolide inhibited FLS migration and invasion under hypoxic conditions in a dose-dependent manner. The upregulation of MMP-1, MMP-3 and MMP-9 in response to hypoxia was significantly (P<0.05) attenuated by andrographolide. Moreover, the expression and DNA binding activity of HIF-1α were dose-dependently decreased in andrographolide-treated cells under hypoxic conditions. Overexpression of HIF-1α almost completely reversed the suppressive effects of andrographolide on the migration, invasion and MMP expression of hypoxic RA-FLSs. These results indicate the ability of andrographolide to attenuate hypoxia-induced invasiveness of RA-FLSs via inhibition of HIF-1α signaling, and warrant further exploration of andrographolide for the treatment of RA.

Li GF ，Qin YH ，Du PQ 《-》

STAT3/HIF-1α/fascin-1 axis promotes RA FLSs migration and invasion ability under hypoxia.

Rheumatoid arthritis (RA) synovium was identified as "tumor-like" tissues because of the hypoxic microenvironment, significant cell proliferation, and invasion phenotypes. It was reported that hypoxia promoted tumor aggressiveness via up-regulated expression of fascin-1 in cancer. However, the role of fascin-1 in RA synovial hyperplasia and joint injury progression remains unknown. In the current study, we first identified that both fascin-1 and HIF-1α were highly expressed in the RA synovium, in which they were widely colocalized, compared to osteoarthritis(OA). As well, levels of fascin-1 in RA fibroblast-like synoviocytes(FLSs) were found significantly higher than those in OA FLSs. Further, it was demonstrated that the mRNA and protein levels of fascin-1 in RA FLSs were up-regulated in hypoxia (3 % O2) and experimental hypoxia induced by cobalt chloride. Mechanistically, the HIF-1α-mediated hypoxia environment activated the gene expression of the fascin-1 protein, which in turn promoted the migration and invasion of RA FLSs. Accordingly, the restoration of FLSs migration and invasion was observed following siRNA-mediated silencing of fascin-1 and HIF-1α expression. Notably, under the experimental hypoxia, we found that the expression levels of fascin-1, HIF-1α, and p-STAT3 were increased in a time-dependent manner, and fascin-1and HIF-1α expressions were dependent on p-STAT3. Our results indicated that hypoxia-induced fascin-1 up-regulation promoted RA FLSs migration and invasion through the STAT3/HIF-1α/fascin-1 axis, which might represent a novel therapeutic target for the treatment of RA.

Yang W ，Wei X ，Jiao Y ，Bai Y ，Sam WN ，Yan Q ，Sun X ，Li G ，Ma J ，Wei W ，Tian D ，Zheng F ... -  《-》

Sustained Hypoxia Suppresses Joint Destruction in a Rat Model of Rheumatoid Arthritis via Negative Feedback of Hypoxia Inducible Factor-1α.

Kaihara K ，Nakagawa S ，Arai Y ，Inoue H ，Tsuchida S ，Fujii Y ，Kamada Y ，Kishida T ，Mazda O ，Takahashi K ... -  《INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES》