Beneficial effect of galectin 9 on rheumatoid arthritis by induction of apoptosis of synovial fibroblasts

Abstract

Objective. To compare the expression of galectin 9 (Gal-9) in synovial tissue (ST) from rheumatoid arthritis (RA) patients and osteoarthritis (OA) patients and to evaluate the effects of Gal-9 on fibroblast-like synoviocytes (FLS) in these patients.Methods. The expression of Gal-9 in ST and FLS was compared using immunohistochemical techniques. Apoptotic cells in RA and OA ST samples were detected by TUNEL assay. Apoptosis of FLS was analyzed by the sub-G 1 method in vitro. The in vivo suppressive effects of Gal-9 on collagen-induced arthritis (CIA) in a mouse model were also elucidated.Results. The percentage of Gal-9-positive cells in ST samples and the amount of Gal-9 in synovial fluid samples were significantly higher in patients with RA than in patients with OA, suggesting the involvement of Gal-9 in the development of RA. Compared with the 2 wild-type Gal-9 forms, stable Gal-9, a mutant protein resistant to proteolysis, significantly induced apoptosis of FLS from RA patients. In contrast, other galectins, such as Gal-1, Gal-3, and Gal-8, did not induce apoptosis or suppress the proliferation of human RA FLS. Stable Gal-9 preferentially induced apoptosis and suppressed the proliferation of RA FLS in vitro. It also induced apoptosis of cells in RA ST implanted into SCID mice in vivo. In a mouse model of CIA, apoptotic cells were detected in the joints of stable Gal-9-treated mice, but not phosphate buffered saline-treated mice, and suppressed CIA characterized by pannus formation with inflammatory cell infiltration and bone/cartilage destruction.Conclusion. Gal-9-induced apoptosis of hyperproliferative RA FLS may play a critical role in the suppression of RA.

Dysregulation of TIM-3–Galectin-9 Pathway in the Cystic Fibrosis Airways

“…Indeed, disruption of this mechanism using TIM-3 or galectin-9 blocking Abs has been reported to result in increased neutrophil infiltration and tissue damage in a model of liver ischemia/reperfusion (31), experimental adhesion formation (30), and multiple sclerosis (32). Conversely, administration of proteolytically stable recombinant galectin-9 ameliorated symptoms in a model of arthritis (34,35,66), diabetes (67), and multiple sclerosis (32). Galectin-9 has also shown to exhibit a protective effect in lung infection in a mouse model of hypersensitivity pneumonitis induced by Trichosporon asahii (41).…”

“…Proteolytically stable human galectin-9 was a kind gift from GalPharma (Kagawa, Japan). Expression and purification of stable human galectin-9 was performed as previously described (34,35). In brief, galectins were expressed using the pET expression system (Novagen, Madison, WI) in Escherichia coli BL21 (DE3) and purified with a lactose-agarose column (Seikagaku Kogyo, Tokyo, Japan) and dialyzed against PBS.…”

“…BAL samples were diluted 1:10 in PBS (final volume, 100 ml) for IL-8 quantification by ELISA to ensure that the values were within the range of detection. Concentrations of galectin-9 in BAL were determined using a custommade sandwich ELISA as previously described (35,41). In brief, 96-well plates (Nunc, Naperville, IL) were coated with an anti-human galectin-9 mAb (9S2-3; GalPharma), blocked with 3% (w/v) BSA containing 0.05% (v/v) Tween 20 in PBS, and then incubated for 1 h at 37˚C with BAL (100 ml) or known concentrations of recombinant human galectin-9.…”

Increased Levels of Plasma Galectin-9 in Patients with Influenza Virus Infection

“…Gal-9 concentrations in the plasma and culture supernatants were measured using ELISA, as previously described with slight modification (Seki et al 2007;Katoh et al 2010). Briefly, 96-well plates (Nunc, Rockild, Denmark) were coated with an anti-human Gal-9 monoclonal antibody (clone 9S2-3; GalPharma, Takamatsu, Japan), and then samples were incubated for 1 hour at 37°C after blocking.…”

Apoptosis Resistance in Rheumatoid Arthritis Synovial Tissue

“…TIM-3 expression could be increased in healthy T-cells, but not in RA-derived T-cells, by treating the cells with the TIM-3 ligand, galectin-9 [76]. These results have even greater significance in view of previous findings which showed that a stable form of galectin-9, resistant to proteolysis unlike the other galectin isoforms, galactin-1, galactin-3, and galactin-8 stimulated RAFLS apoptosis and suppressed proliferation in vitro [77]. Thus, galectin-9-mediated CD4 + cell apoptosis appears to be deficient in RA.…”