Immunohistochemical distribution of advanced glycation end products (AGEs) in human osteoarthritic cartilage

Advanced glycation end products (AGEs) may be associated with osteoarthritis (OA), because the accumulation of AGEs in articular cartilage are among the most striking age-related changes. AGEs modify the tissue protein structure and function and stimulate the cellular responses mediated by a specific receptor for AGEs (RAGE). This study investigated the localization of AGEs in degenerated cartilage using newly identified epitope-specific antibodies to determine the linkage between the distribution of AGEs and the development and progression of OA. Osteochondral specimens of the tibial plateau from OA patients were immunostained by specific antibodies against N^?-(carboxymethyl)lysine (CML), N^?-(carboxyethyl)lysine (CEL), pentosidine, GA-pyridine, and RAGE. The immunohistochemical distribution of these epitopes was evaluated during cartilage degeneration. The immunoreactivity (IR) of AGEs and RAGE was stronger in cells rather than in the extracellular matrix. Higher IR of cellular CML and CEL was observed in both mild and severe OA cartilage in comparison to macroscopically intact cartilage. There was a strong association between GA-pyridine and RAGE in the pattern of increasing IR with the OA grade. These IR patterns of AGEs varying with cartilage degeneration indicate that AGE modified proteins are associated with cartilage degeneration. The coincidental up-regulation of GA-pyridine and RAGE suggests that GA-pyridine is the most significant AGE for cartilage degeneration via the RAGE pathway.     

SOX Trio Decrease in the Articular Cartilage with the Advancement of Osteoarthritis

SOX trio (SOX-5, SOX-6, and SOX-9) maintain the chondrocytic phenotypes and are vital for chondrogenesis in embryonic development. The purpose of this study is to investigate the change in the expression of SOX trio with the advancement of osteoarthritis (OA) in human articular cartilage (AC). Human OA samples from eight patients were obtained from the distal femoral condyles during total knee arthroplasty. Minimally OA cartilage taken from areas with no obvious surface defects on lateral condyles was compared with advanced OA cartilage obtained from areas within 1 cm of overt lesion located on medial condyle surface. SOX-5, SOX-6, and SOX-9 gene expressions significantly decreased by 41% (p = 0.047), 46% (p = 0.047), and 56% (p = 0.029) in advanced OA area compared with the minimally OA area. There was a significant decrease in aggrecan and type II collagen (COL2A1) gene expressions by 73% (p = 0.029) and 65% (p = 0.029), respectively, in advanced OA area compared with the minimally OA area. From Western blotting and immunohistochemistry, SOX-5, SOX-6, SOX-9, type II collagen, and aggrecan protein expressions also significantly decreased in advanced OA cartilage compared with minimally OA cartilage. DNA methylation study of SOX-9 promoter regions revealed no difference in the epigenetic status between the two areas. It is concluded that SOX trio gene and protein decreased with advancement of OA in human articular cartilage.     

Expression of receptor for advanced glycation end products and HMGB1/amphoterin in colorectal adenomas

Receptor for advanced glycation end products (RAGE) is associated with invasion, metastasis, and poor prognosis in colorectal cancer. We studied the expression of RAGE in colorectal adenomas to elucidate the role of RAGE in cancer development. Expressions of RAGE and high-mobility group box-1 (HMGB1)/amphoterin RAGE ligand were examined in 96 colorectal adenomas using immunohistochemistry and in situ hybridization, respectively. Positivity and expression pattern of RAGE were compared with atypia, histological types, size, and HMGB1/amphoterin expression. Of 96 adenomas, 34 (35%) showed RAGE expression. RAGE positivity was significantly higher in adenomas with severe atypia (18/20, P<0.0001) and large-sized adenomas (–15 mm) (18/22, P<0.0001). RAGE expression showed three patterns: cytosolic (n=10), luminal (n=14), and membranous (n=10). Cytosolic pattern was associated with mild atypia and small size (–5 mm). Membranous pattern was associated with severe atypia, villous histological type, and co-expression with overexpressed HMGB1/amphoterin. These results suggest that RAGE expression, especially with membranous pattern, is associated with malignant potential of colorectal adenomas.     

Male subjects with early-stage knee osteoarthritis do not present biomechanical alterations in the sagittal plane during stair descent

Patients with osteoarthritis (OA) of the knee show a loss of functional independence due to difficulty performing tasks that require high demand of the knee joint, such as descending stairs. However, it is unclear how muscular and biomechanical changes were present in patients with OA in the early stages. Thus, the purpose of this study was to analyze the kinetics, kinematics and muscle activation of men with early-stage knee OA during stair descent and compare them with a healthy control group. We evaluated 31 volunteers who were divided into two groups. The Osteoarthritis Group (OAG) included 17 men with grade I or II knee OA (53 ± 6 years) and the Control Group (CG) included 14 healthy men (50 ± 6 years). We performed a kinematic evaluation of stair descent in the sagittal plane in order to analyze knee flexion angles. Electromyography (EMG) of the vastus lateralis muscle was also performed and the vertical ground reaction force was measured. The WOMAC questionnaire was administered to all volunteers. Statistical analysis consisted of the nonparametric Mann-Whitney U test for intergroup comparisons of all variables (p>0.05). There were no significant kinematic, kinetic or EMG differences between groups. For the WOMAC, the intergroup differences were significant in all three sections (pain: p=0.001, stiffness: p=0.008 and function: p=0.0005). In men with knee OA grade I or II, the stair decent is preserved in the sagittal plane, indicating that at these stages of the disease the functional adaptations are not expressed.     

Strain and elongation of the vastus lateralis aponeurosis and tendon in vivo during maximal isometric contraction

The strain and elongation of the vastus lateralis (VL) tendon, tendon plus aponeurosis, and aponeurosis were examined during maximal voluntary contractions on a Biodex-dynamometer (knee angle 115°, hip angle 140°) in 12 sprinters. Following a warm-up phase, the subjects were instructed to perform a gradual maximal knee extension and hold it for about 3 s. The kinematics of the leg were recorded using a Vicon 512 system with eight cameras operating at 120 Hz. Ultrasonography images were taken simultaneously from the VL myotendinous junction and the mid lateral part of the VL muscle belly. During the maximal isometric knee extensions, the knee joint rotated (13.6±5.9°), leading to an overestimation of the elongation of the tendinous tissues. After correcting for this, the maximal elongation of the VL tendon examined at the myotendinous junction was lower (P<0.05) than the maximal elongation of the VL tendon plus aponeurosis examined at the muscle belly (15 vs. 27 mm, respectively). The maximal estimated strains of the tendon, tendon plus aponeurosis, and aponeurosis showed no statistical differences (8±2%, 8±1%, and 7±2%, respectively, P>0.05). It is concluded that the strains of the human VL tendon, VL tendon plus aponeurosis, and VL aponeurosis, as estimated in vivo by two dimensional ultrasound during maximal isometric contractions, do not differ from each other. The displacement measured at a cross point in the VL muscle belly is significantly greater than that measured at the VL myotendinous junction.     

COX-2在膝关节骨性关节炎软骨中表达及临床意义

目的研究环氧化酶-2基因在膝关节骨性关节炎（osteoarthritis,OA）患者软骨组织的表达及其临床意义。方法对40例膝关节骨性关节炎取患者软骨组织设为OA组和7例膝关节正常软骨组织设为对照组。分别提取两组软骨组织RNA和总蛋白,通过RT-PCR检测各组COX-2mRNA转录水平以及COX-2基因表达蛋白Westernblot分析。结果 RT-PCR结果显示OA组出现大小约700bp条带,对照组扩增条带不明显;Western blot分析结果OA组COX-2基因表达蛋白明显,两组间灰度比有显著差异（〈0.05）。结论 COX-2基因及其表达蛋白在膝关节骨性关节炎软骨组织损害过程中起到重要作用。     

Effect of S-methylisothiourea,an inducible nitric oxide synthase inhibitor,in joint pain and pathology in surgically induced model of osteoarthritis

The aim of the present study was to evaluate in vivo modulatory effect of S-methylisothiourea (SMT), a preferential inhibitor of inducible nitric oxide synthase (iNOS) on pain and pathology in the surgical model of osteoarthritis (OA) in rats. The OA was produced by the anterior cruciate ligament transection (ACLT) and medial meniscectomy (MMx) of right knee. SMT was administered 1 day prior to the production of OA and continued up to day 42 postoperation. Mechanical hyperalgesia, thermal hyperalgesia, tail flick latency after repeated flexion and extension of OA knee and knee diameter of right knee were determined at weekly intervals. Serum levels of IL-1β, TNF-α and nitrite concentration were determined at the end of the experiment. Glycosaminoglycan (GAG) content, collagen content and histopathological evaluation of articular cartilage were also determined at the end of the experiment. SMT reduced mechanical hyperalgesia and the serum levels of IL-1β, TNF-α and nitrite. Further, SMT reduced the loss of GAG from articular cartilage. Microscopically, SMT reduced the severity of the cartilage lesion. The results indicate the effectiveness of SMT in attenuating the pain and pathology of experimental OA phase by reducing the production of nitric oxide and interleukin-1β and tumor necrosis factor-α, which are known to play a major role in the pathophysiology of OA.     

Association between CCL2 haplotypes and knee osteoarthritis

We examined five single nucleotide polymorphisms (SNPs) and reconstructed 5‐locus haplotypes of the CCL2 gene, in knee osteoarthritis (OA) cases and in controls. The CCL2 rs2857657 variant (G) allele was observed more frequently in female knee OA cases than in controls. One haplotype (H5) was observed exclusively in the control group (f = 2.3%). Genetic variation in the CCL2 gene may be associated with knee OA.     

CXCL8 and CCL5 expression in synovial fluid and blood serum in patients with osteoarthritis of the knee

Chemokines proved able to induce release of enzymes relevant in cartilage damage. The present study addressed the levels of CXCL8 and CCL5 and the potential role of these chemokines in predicting the morphological changes in the course of osteoarthritis (OA). Synovial fluid (SF) and blood serum were obtained from 20 patients undergoing knee replacement surgery because of OA. For comparison, samples were also obtained from another 20 patients during diagnostic or therapeutic arthroscopy performed because of knee injury. The samples were analyzed for CXCL8 and CCL5 using enzyme-linked immunosorbent assay. SF from the group with OA showed significantly (p = 0.024) increased levels of CXCL8 when compared with the group after knee injury. We have not demonstrated any significant correlation between chemokine expression and clinical or radiological signs of OA. Mediators of inflammation are the potential predicting factors of OA, however, with respect to examined chemokines development of a diagnostic test can be limited by the low serum concentration and lack of correlation with clinical and radiological signs of the disease.