Intraperitoneal injection of the SIRT1 activator SRT1720 attenuates the progression of experimental osteoarthritis in mice

Abstract

Objectives: This study aimed to examine the effects of SRT1720, a potent SIRT1 activator, on osteoarthritis (OA) progression using an experimental OA model.

Methods: Osteoarthritis was surgically induced by destabilization of the medial meniscus in eight-week-old C57BL/6 male mice. SRT1720 was administered intraperitoneally twice a week after surgery. Osteoarthritis progression was evaluated histologically using the Osteoarthritis Research Society International (OARSI) score at four, eight, 12 and 16 weeks. The expression of SIRT1, matrix metalloproteinase 13 (MMP-13), a disintegrin and metalloproteinase with thrombospondin motifs-5 (ADAMTS-5), cleaved caspase-3, PARP p85, and acetylated nuclear factor (NF)-κB p65 in cartilage was examined by immunohistochemistry. Synovitis was also evaluated histologically. Primary mouse epiphyseal chondrocytes were treated with SRT1720 in the presence or absence of interleukin 1 beta (IL-1β), and gene expression changes were examined by real-time polymerase chain reaction (PCR).

Results: The OARSI score was significantly lower in mice treated with SRT1720 than in control mice at eight and 12 weeks associated with the decreased size of osteophytes at four and eight weeks. The delayed OA progression in the mice treated with SRT1720 was also associated with increased SIRT1-positive chondrocytes and decreased MMP-13-, ADAMTS-5-, cleaved caspase-3-, PARP p85-, and acetylated NF-κB p65-positive chondrocytes and decreased synovitis at four and eight weeks. SRT1720 treatment partially rescued the decreases in collagen type II alpha 1 (COL2A1) and aggrecan caused by IL-1β, while also reducing the induction of MMP-13 by IL-1β in vitro.

Conclusion: The intraperitoneal injection of SRT1720 attenuated experimental OA progression in mice, indicating that SRT1720 could be a new therapeutic approach for OA.Cite this article: K. Nishida, T. Matsushita, K. Takayama, T. Tanaka, N. Miyaji, K. Ibaraki, D. Araki, N. Kanzaki, T. Matsumoto, R. Kuroda. Intraperitoneal injection of the SIRT1 activator SRT1720 attenuates the progression of experimental osteoarthritis in mice. Bone Joint Res 2018;7:252-262. DOI: 10.1302/2046-3758.73.BJR-2017-0227.R1.

Keywords: Osteoarthritis; SIRT1; SRT1720; Synovitis.

a) Safranin O staining of the knee joints at four, eight, 12 and 16 weeks (scale bar = 100 µm). Representative images are shown from repeated experiments; b) the OARSI scores for the medial femoral condyle and tibial condyle in the control mice and mice treated with SRT1720. Three sections were selected from the lateral, middle and medial one-third of the condyle from each mouse. *p < 0.05). c) immunohistochemistry for type II collagen in the medial tibial plateau at eight weeks (scale bars = 50 μm) and quantitative analysis of the type II collagen-positive cells. The positive cells were counted and expressed as a percentage of the positive cells. Three sections were selected from each mouse; d) osteophyte development on the anterior tibial plateau (arrows, scale bars = 100 μm); e) the mean scores of osteophyte maturity; f) the mean scores of osteophyte size (n = 5 male mice for each timepoint / group; *p < 0.05).

a) Immunohistochemistry of SIRT1 in the medial tibial plateau at four, eight, 12 and 16 weeks following surgery (scale bars = 50 μm); b) the percentage of SIRT1-positive cells. Three micrographs of the medial tibial plateau were taken under ×40 magnification. The percentage of SIRT1-positive chondrocytes was determined as (positive cells/total number of cells) × 100 (n = 5 male mice for each timepoint / group; *p < 0.05).

a) Immunohistochemistry analysis of ADAMTS-5 at four, eight and 12 weeks; b) the percentage of ADAMTS-5-positive cells; c) immunohistochemistry analysis of MMP-13 at four, eight and 12 weeks; d) the percentage of MMP-13-positive cells; e) immunohistochemistry analysis of cleaved caspase-3, PARP p85 and acetylated NF-κB at eight weeks, and the percentage of positive cells. Scale bar = 50 μm. The positive cells were counted using a total of five male mice for each timepoint/group. Three sections were selected from each mouse (*p < 0.05).

a) H&E staining of the synovium in the knee joints at four, eight and 12 weeks. Representative images are shown from repeated experiments; b) the synovitis score. Values are the mean and sd; c) immunohistochemistry analysis of IL-1β in the synovium. Representative images are shown from repeated experiments. Scale bar = 50 μm (n = 5 male mice for each timepoint/group; *p < 0.05).

Fig. 5

Real-time polymerase chain reaction (PCR) analysis of SIRT1, Col1a1, Col2a1, aggrecan and Mmp-13 in mouse primary chondrocytes. Primary mouse epiphyseal chondrocytes were cultured with 0.1 ng/ml IL-1β for 24 hours and then stimulated with 0.5 µM SRT1720 for 48 hours. The values are the mean and sd of three independent experiments (*p < 0.05).