Cartilage Proteoglycan Depletion Research Articles

A novel Osteoarthritis scoring system to separate typical OA joint degeneration from non-typical lesions in male Sprague Dawley rats

ObjectiveTo develop a novel scoring system to characterize osteoarthritis-related degeneration distinct from spontaneous subchondral bone lesions observed in the tibia and femur of male Sprague Dawley rats. MethodKnee joints from male rats following 12 weeks of a diet-induced obesity model of osteoarthritis (OA) were assessed. OA histopathological changes (OAHC) were assessed in the knee joints. All scores were evaluated using a modified Mankin score and a modified Osteoarthritis Research Society International histological score. OAHC were divided into 3 categories: (I) Typical OA score evaluating the changes in cartilage structure, cellularity, proteoglycan depletion, and tidemark integrity, (II) A novel Non-typical OA score evaluating cartilage integrity, and the size of local thickening, fragmentation and degeneration along the tidemark and the size and severity of the subchondral bone lesion, and (III) Total OA score comprised of both, the Typical and the Non-typical scores. ResultsRats exposed to a high fat/high sucrose diet had higher Typical OA score compared to a control group (Chow). Non-typical and Total OA scores revealed no differences in the severity of the lesions between the HFS and the Chow group animals. All scoring systems had excellent intra- and inter-examiner reliability. ConclusionThe spontaneous bone lesions observed in male Sprague Dawley rats can obscure the effect of the diet-induced obesity if the classical scoring system is used to assess joint degeneration. The newly proposed scoring method provides a reliable method to distinguish classical OA joint degeneration from spontaneous Non-typical lesions occurring in these rats.

A serial multiparametric quantitative magnetic resonance imaging study to assess proteoglycan depletion of human articular cartilage and its effects on functionality

Water, collagen, and proteoglycans determine articular cartilage functionality. If altered, susceptibility to premature degeneration is increased. This study investigated the effects of enzymatic proteoglycan depletion on cartilage functionality as assessed by advanced Magnetic Resonance Imaging (MRI) techniques under standardized loading. Lateral femoral condylar cartilage-bone samples from patients undergoing knee replacement (n = 29) were serially imaged by Proton Density-weighted and T1, T1ρ, T2, and T2* mapping sequences on a clinical 3.0 T MRI scanner (Achieva, Philips). Using pressure-controlled indentation loading, samples were imaged unloaded and quasi-statically loaded to 15.1 N and 28.6 N, and both before and after exposure to low-concentrated (LT, 0.1 mg/mL, n = 10) or high-concentrated trypsin (HT, 1.0 mg/mL, n = 10). Controls were not treated (n = 9). Responses to loading were assessed for the entire sample and regionally, i.e. sub- and peri-pistonally, and zonally, i.e. upper and lower sample halves. Trypsin effects were quantified as relative changes (Δ), analysed using appropriate statistical tests, and referenced histologically. Histological proteoglycan depletion was reflected by significant sub-pistonal decreases in T1 (p = 0.003) and T2 (p = 0.008) after HT exposure. Loading-induced changes in T1ρ and T2* were not related. In conclusion, proteoglycan depletion alters cartilage functionality and may be assessed using serial T1 and T2 mapping under loading.

GagCEST MRI at 3T can detect cartilage differences between healthy and osteoarthritic subjects

Purpose: Evaluation of osteoarthritis (OA) is hampered by a lack of non-invasive tools to effectively detect early and reversible changes associated with the disease. Early OA is characterized by cartilage proteoglycan depletion related to an increase in enzymatic degradation. GagCEST is a promising quantitative MR technique for assessing content of Glycosaminoglycan (GAG) side chains attached to proteoglycans at 7T and is of particular interest due to its specificity to GAG content without the use of exogenous contrast agents or specialized hardware. While gagCEST has been shown to be a useful biomarker for cartilage composition at 7T, there is limited evidence of its utility at 3T. In this study, we assess the utility of an optimized gagCEST protocol at 3T by comparing gagCEST asymmetry in subjects with established OA to healthy controls. Methods: Ten healthy subjects (5 female and 5 male, ages 20-30) and twenty-four subjects with medial compartment OA were scanned on a 3T MRI system. The OA cohort (ages 60-70) was grouped by Kellgren-Lawrence (KL) grade (assessed using radiography) with five subjects with a KL grade of 1 (4 female and 1 male), twelve with a KL grade of 2 (8 female and 4 male), and five with a KL grade of 3 (4 female and 3 male). Other inclusion criteria included no previous ACL reconstruction surgery and BMI < 35. GagCEST images were acquired with a magnetization prepared 3D spoiled gradient-echo sequence (imaging parameters in Table 1). After correcting for magnetic field inhomogeneities, gagCEST asymmetry (%) was calculated using the B0-field corrected signal intensity at ±1.0 ppm, and the chemical shift of GAG hydroxyl protons, using the equation: gagCESTasym= [S(-1.0 ppm)-S(+1.0 ppm)]/ S0]. Femoral cartilage was manually segmented and subdivided into medial and lateral subregions. Statistical comparisons between cartilage compartments and healthy vs OA subjects were made using an ANOVA 2-way test with a Tukey HSD Test for multiple comparisons. Results: Subjects with OA showed a reduced gagCEST asymmetry compared to healthy controls. Further, there was a trend of an inverse relationship between GagCEST asymmetry and KL grade. There was a statistically significant difference in gagCEST asymmetry among KL grade values (p = 0.019). Further analysis comparing healthy subjects to the different OA KL grade subjects, showed a significant difference between healthy and OA KL-2 subjects and OA KL-3 subjects (p = 0.022 and p = 0.046 respectively). The comparison between healthy and KL-1 subjects did not show a significant difference (p = 0.536), which may be due to insufficient power in this cohort. There was no statistically significant difference between medial and lateral compartments in the femoral cartilage (p = 0.977). Additionally, a negative correlation of GagCEST with KL grade was observed (r= -0.404, p=0.01). The results show that optimized gagCEST methods at 3T were able to detect a statistically significant reduction in gagCEST asymmetry in osteoarthritic subjects, known to have cartilage degeneration and lower biochemical GAG composition, compared to healthy controls. Further analysis showed a significant difference in gagCEST asymmetry between the healthy and OA KL-2 and KL-3 subjects. This decrease can be seen in the unrolled gagCEST asymmetry maps, especially in the medial compartment of the knee, which corresponds well with the diagnosis in our cohort of medial compartment OA. Further, at a total acquisition time of 8:76 minutes for whole joint coverage, these methods offer translational potential. Conclusions: Our results demonstrate promise for the application of gagCEST at 3T to detect differences between healthy cartilage and cartilage in subjects with OA. Taken together, our results show that GagCEST could be a viable tool to assess early degenerative changes in cartilage in clinical trials. A strength of MRI over X-ray is that it is more sensitive to early changes in cartilage composition that occur due to OA. GagCEST has the potential for distinguishing these changes that are unseen in X-rays because it may be sensitive to signs of changes in GAG content that radiographs are not able to visualize.View Large Image Figure ViewerDownload Hi-res image Download (PPT)View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Anti-citrullinated protein antibodies cause arthritis by cross-reactivity to joint cartilage.

Today, it is known that autoimmune diseases start a long time before clinical symptoms appear. Anti-citrullinated protein antibodies (ACPAs) appear many years before the clinical onset of rheumatoid arthritis (RA). However, it is still unclear if and how ACPAs are arthritogenic. To better understand the molecular basis of pathogenicity of ACPAs, we investigated autoantibodies reactive against the C1 epitope of collagen type II (CII) and its citrullinated variants. We found that these antibodies are commonly occurring in RA. A mAb (ACC1) against citrullinated C1 was found to cross-react with several noncitrullinated epitopes on native CII, causing proteoglycan depletion of cartilage and severe arthritis in mice. Structural studies by X-ray crystallography showed that such recognition is governed by a shared structural motif "RG-TG" within all the epitopes, including electrostatic potential-controlled citrulline specificity. Overall, we have demonstrated a molecular mechanism that explains how ACPAs trigger arthritis.

Effects of BIS076 in a model of osteoarthritis induced by anterior cruciate ligament transection in ovariectomised rats.

BackgroundOsteoarthritis (OA) is the most frequent articular disease and a leading cause of disability. There is a need for effective treatments able to slow the progression of disease. Some of the available treatments are dietary supplements providing natural components. Recent studies have shown that estrogen deficiency contributes to the pathophysiological events of OA progression.MethodsWe have used the anterior cruciate ligament transection model of OA in ovariectomised rats to study the effects of BIS076, a new formulation of a natural porcine cartilage extract associated with hydroxyapatite (as a source of calcium) and vitamin D3. Cartilage degradation, proteoglycan depletion and synovitis were followed by histochemistry. Effects on bone microstructure were determined by μCT. The levels of biomarkers in serum and inflammatory mediators in knee homogenates were measured by luminex or ELISA.ResultsOral administration of BIS076 reduced articular cartilage damage and serum levels of cartilage degradation markers C-telopeptide of type II collagen and cartilage oligomeric matrix protein, as well as matrix metalloproteinase-3. The local inflammatory response was down-regulated by BIS076 with lower production of pro-inflammatory cytokines and prostaglandin E2 in joint tissues. In addition, BIS076 was effective on metaphyseal bone alterations as this formulation increased volumetric bone mineral density and improved bone micro-architecture. These effects were related to the modification of bone metabolism reflected by changes in bone biomarkers with reductions in the ratio receptor activator of nuclear factor κB ligand/osteoprotegerin and the levels of tartrate-resistant acid phosphatase-5b, suggesting an inhibitory activity of BIS076 on trabecular bone resorption.ConclusionsWe have demonstrated the protective properties of a new formulation (BIS076) on joint lesion and bone alterations in an experimental model of OA in ovariectomised rats. This study supports the interest of BIS076 in OA treatments.

Disease-regulated local IL-10 gene therapy diminishes synovitis and cartilage proteoglycan depletion in experimental arthritis

ObjectivesRheumatoid arthritis is a chronic destructive autoimmune disease, but the course is unpredictable in individual patients. An attractive treatment would provide a disease-regulated therapy that offers personalised drug delivery. Therefore,...

AB0104 Develop and Evaluate a New Modified Mankin Score System with Special Attention to Subchondral Bone

BackgroundThe MANKIN score is the most widely used histology evaluation on osteoarthritis (OA). It has been modified in number of studies by different research groups since it was first published...

A5.14 Disease-regulated local interleukin-10 gene therapy diminishes synovitis and articular cartilage damage in experimental arthritis

Background and ObjectivesRheumatoid arthritis (RA) is a chronic destructive autoimmune disease with periods of exacerbation and remission. An attractive treatment would provide a disease-regulated therapy that offers flexible drug delivery....

Histamine contributes to increased RANKL to osteoprotegerin ratio through altered nuclear receptor 4A activity in human chondrocytes

To elucidate histamine receptor-mediated signaling pathways, transcriptional events, and target gene expression in human cartilage. Histamine modulation of cartilage destruction was assessed by Safranin O staining and proteoglycan release. H(1) , H(2) , H(3) , and H(4) histamine receptor-dependent regulation of transcription factors (nuclear receptor 4A1 [NR4A1], NR4A2, and NR4A3), RANKL, and osteoprotegerin (OPG) messenger RNA (mRNA) levels were measured in primary and SW-1353 chondrocyte cells using quantitative polymerase chain reaction and selective histamine receptor antagonists. Soluble RANKL and OPG protein levels were determined using enzyme-linked immunosorbent assays. NR4A protein levels and transactivity were evaluated by Western blot analysis, immunocytochemistry, and luciferase reporter assays. Stable depletion of NR4A1-3 was achieved by lentiviral transduction of NR4A short hairpin RNA. Primary human chondrocyte cells expressed differential steady-state levels of H(1) -H(4) histamine receptor mRNA. In combination with tumor necrosis factor α, histamine significantly promoted cartilage proteoglycan depletion and release. Histamine modulated the expression of NR4A1-3 orphan receptors in primary and immortalized human chondrocyte cells in a time- and concentration-dependent manner. Histamine selectively signaled through H(1) and H(2) histamine receptors in chondrocytes to modulate RANKL and NR4A2 expression. The temporal effects of histamine on NR4A2 gene transcription were reduced in cells pretreated with inhibitors directed against protein kinase A, MAPK, and NF-κB signaling pathways. Histamine modulated the expression of RANKL with modest effects on OPG levels, leading to increased RANKL:OPG mRNA and protein ratios. Stable knockdown of NR4A1-3 expression resulted in reduced endogenous OPG levels and the loss of histamine-dependent regulation of RANKL expression. Our findings indicate that histamine, via H(1) and H(2) histamine receptors, contributes to joint disease by enhancing the ratio of RANKL to OPG expression through altered NR4A activity in human chondrocyte cells.

Dual role of IL-21 in experimental arthritis via SOCS regulation and Th17 differentiation

ObjectivesInterleukin-21 (IL-21) is a pleiotropic cytokine that is produced mainly by activated CD4+ Th17 cells. The purpose of this study was to investigate the role of IL-21 in joint pathology...

Analysis of osteoarthritis in a mouse model of the progeroid human DNA repair syndrome trichothiodystrophy

The increasing average age in developed societies is paralleled by an increase in the prevalence of many age-related diseases such as osteoarthritis (OA), which is characterized by deformation of the joint due to cartilage damage and increased turnover of subchondral bone. Consequently, deficiency in DNA repair, often associated with premature aging, may lead to increased pathology of these two tissues. To examine this possibility, we analyzed the bone and cartilage phenotype of male and female knee joints derived from 52- to 104-week-old WT C57Bl/6 and trichothiodystrophy (TTD) mice, who carry a defect in the nucleotide excision repair pathway and display many features of premature aging. Using micro-CT, we found bone loss in all groups of 104-week-old compared to 52-week-old mice. Cartilage damage was mild to moderate in all mice. Surprisingly, female TTD mice had less cartilage damage, proteoglycan depletion, and osteophytosis compared to WT controls. OA severity in males did not significantly differ between genotypes, although TTD males had less osteophytosis. These results indicate that in premature aging TTD mice age-related changes in cartilage were not more severe compared to WT mice, in striking contrast with bone and many other tissues. This segmental aging character may be explained by a difference in vasculature and thereby oxygen load in cartilage and bone. Alternatively, a difference in impact of an anti-aging response, previously found to be triggered by accumulation of DNA damage, might help explain why female mice were protected from cartilage damage. These findings underline the exceptional segmental nature of progeroid conditions and provide an explanation for pro- and anti-aging features occurring in the same individual.

Local Interleukin-1-Driven Joint Pathology Is Dependent on Toll-Like Receptor 4 Activation

Toll-like receptors (TLRs) may contribute to the pathogenesis of chronic inflammatory destructive diseases through the recognition of endogenous ligands produced on either inflammation or degeneration of the extracellular matrix. The presence of endogenous TLR agonists has been reported in rheumatoid joints. In the present study, we investigated the significance of TLR2 and TLR4 activation by locally- produced endogenous ligands in the severity of joint inflammation and destruction. Local joint pathology independent of systemic immune activation was induced by overexpression of interleukin (IL)-1 and TNF in naive joints using adenoviral gene transfer. Here, we report that at certain doses, IL-1-induced local joint inflammation, cartilage proteoglycan depletion, and bone erosion are dependent on TLR4 activation, whereas TLR2 activation is not significantly involved. In comparison, tumor necrosis factor alpha-driven joint pathology seemed to be less dependent on TLR2 and TLR4. The severity of IL-1-induced bone erosion and irreversible cartilage destruction was markedly reduced in TLR4(-/-) mice, even though the degree of inflammation was similar, suggesting uncoupled processes. Furthermore, the expression of cathepsin K, a marker for osteoclast activity, induced by IL-1beta was dependent on TLR4. Overexpression of IL-1beta in the joint as well as ex vivo IL-1 stimulation of patellae provoked the release of endogenous TLR4 agonists capable of inducing TLR4-mediated cytokine production. These data emphasize the potential relevance of TLR4 activation in rheumatoid arthritis, particularly with respect to IL-1-mediated joint pathology.

Telopeptides of type II collagen upregulate proteinases and damage cartilage but are less effective than highly active fibronectin fragments

We hypothesize that N-telopeptide (NT) and C-telopeptides (CT) of type II collagen can enhance proteinases and cause cartilage damage and have compared damaging activities to an extensively characterized potent fibronectin fragment (Fn-f). NT and CT peptides were synthesized. Interaction of labeled peptides with chondrocytes was studied by fluorescence microscopy. Effects on the metalloproteinases (MMPs) MMP-3 and MMP-13 and on ADAMTS-5 were analyzed by western blotting. Cartilage damage was assayed by loss of proteoglycan (PG) from cultured explants. NT and CT peptides penetrated cartilage, bound to chondrocytes and enhanced proteinase release and cartilage PG depletion. Peptides had detectable activity at 0.3 microM (1 microg/ml) and were comparable at 30 microM (100 microg/ml) to 1 microM Fn-f (29 microg/ml). However, while the Fn-f enhanced IL-1beta and TNF-alpha, the NT and CT peptides did not. Collagen peptides containing NT and CT regions were less active on a molar basis than Fn-fs but were still potent damaging agents. Since collagen fragments are found in OA cartilage at microg/ml, they have the potential to play a role in physiologic cartilage damage.

Human rheumatoid arthritis tissue production of IL-17A drives matrix and cartilage degradation: synergy with tumour necrosis factor-alpha, Oncostatin M and response to biologic therapies.

IntroductionThe aim of this study was to examine IL-17A in patients, following anti-TNF-α therapy and the effect of IL-17A on matrix turnover and cartilage degradation.MethodsIL-17A expression was examined by ELISA and immunohistology in the rheumatoid arthritis (RA) joints. RA whole synovial tissue explant (RA ST), primary synovial fibroblasts (RASFC), human cartilage and chondrocyte cultures were stimulated with IL-17A +/- TNF-α and Oncostatin M (OSM). Matrix metalloproteinase (MMP) and tissue inhibitor (TIMP-1) were assessed by ELISA and zymography. Cartilage proteoglycan release was assessed histologically by Safranin-O staining. Clinical parameters, IL-17A, MMP/TIMP were assessed in patients pre/post biologic therapy.ResultsIL-17A levels were higher in RA vs osteoarthritis (OA)/normal joints (P < 0.05). IL-17A up-regulated MMP-1, -2, -9, and -13 in RA ST, RASFC, cartilage and chondrocyte cultures (P < 0.05). In combination with TNF-α and OSM, IL-17A shifted the MMP:TIMP-1 ratio in favor of matrix degradation (all P < 0.05). Cartilage proteoglycan depletion in response to IL-17A was mild; however, in combination with TNF-α or OSM showed almost complete proteoglycan depletion. Serum IL-17A was detected in 28% of patients commencing biologic therapy. IL-17A negative patients demonstrated reductions post therapy in serum MMP1/TIMP4, MMP3/TIMP1 and MMP3/TIMP4 ratios and an increase in CS846 (all P < 0.05). No significant changes were observed in IL-17A positive patients.ConclusionsIL-17A is produced locally in the inflamed RA joint. IL-17A promotes matrix turnover and cartilage destruction, especially in the presence of other cytokines, mimicking the joint environment. IL-17A levels are modulated in vivo, following anti-TNF therapy, and may reflect changes in matrix turnover.

The cartilage chondrolytic mechanism of fibronectin fragments involves MAP kinases: comparison of three fragments and native fibronectin

To define the role of mitogen activated protein (MAP) kinases in fibronectin fragment (Fn-f) mediated matrix metalloproteinase (MMP) upregulation and damage to bovine cartilage and to compare activities of three Fn-fs with native fibronectin (Fn), which is inactive in terms of cartilage damage. Bovine chondrocytes were cultured with three Fn-fs, an amino-terminal 29-kDa, a gelatin-binding 50-kDa and a central 140-kDa Fn-f or native Fn at concentrations from 0.01 to 1 microM, concentrations lower than those found in osteoarthritis synovial fluids. Lysates were probed for activation of MAP kinases, extracellular signal-regulated kinase 1/2 (ERK1/2), p38 and stress activated protein kinase/c-jun N-terminal kinase (SAPK/JNK). Confocal fluorescent microscopy was used to visualize movement of activated kinases. Kinase inhibitors were tested for their abilities to block Fn-f mediated protein upregulation of MMP-3 and MMP-13 and Fn-f induced depletion of cartilage proteoglycan (PG) from cultured explants. The 29-kDa, the most potent Fn-f in terms of cartilage damage, enhanced phosphorylation of ERK1/2, p38 and JNK1/2 within a 1-h incubation while the 50 and 140-kDa Fn-fs required up to 4 h for maximal activity and native Fn was only minimally active toward p38 and JNK, but did strongly activate ERK1/2. The activated kinases displayed a distribution toward the nuclear membrane and within the nucleus. MAP kinase inhibitors markedly decreased Fn-f mediated upregulation of MMP-3 or MMP-13 and Fn-f mediated cartilage PG depletion. These results suggest that Fn-fs upregulate MMP-3 and MMP-13 in bovine chondrocytes through MAP kinases and that kinase inhibitors afford protection against this degenerative pathway.

Anti-inflammatory effects of orally ingested lactoferrin and glycine in different zymosan-induced inflammation models: Evidence for synergistic activity

There is a growing awareness of the interaction of food constituents with the immune system. The present study aims to evaluate the anti-inflammatory effects of two of these nutritional components (glycine and bovine-lactoferrin (b-LF)) using two different mouse models.In a zymosan-induced ear–skin inflammation model both components decreased the inflammatory response locally (ear swelling and inflammatory cytokine concentration in the ears) and systemically (number of TNF-α producing spleen cells). Glycine effects (20, 50 or 100 mg/mouse/day) were concentration dependent. B-LF (0.1 or 1 mg/mouse/day) inhibited the inflammatory response although higher doses (5 and 25 mg/mouse/day) were not effective. A combination of b-LF 0.1 mg/mouse/day and glycine 20 or 50 mg/mouse/day counteracted the zymosan-induced ear swelling synergistically and enhanced the decrease in the number of TNF-α producing spleen cells of the individual components.In a zymosan-induced acute arthritis model glycine (50 mg/mouse/day) inhibited joint swelling, inflammatory cell infiltration and cartilage proteoglycan depletion. A b-LF dose of 5 mg/mouse/day reduced the zymosan-induced joint swelling without modulating inflammatory cell infiltration and cartilage proteoglycan depletion.The present study indicates that the anti-inflammatory effects of glycine are independent of the used models. B-LF displays a reversed concentration dependency and the activity is model dependent. A combination of glycine and lactoferrin demonstrated a synergistic anti-inflammatory effect on zymosan-induced skin inflammation and an enhanced decrease in the number of TNF-α producing spleen cells compared to the effect of the single components. Therefore, this nutritional concept might be a new option for the treatment of chronic inflammatory diseases.

Connective tissue growth factor/CCN2 overexpression in mouse synovial lining results in transient fibrosis and cartilage damage

Characteristics of osteoarthritis (OA) include cartilage damage, fibrosis, and osteophyte formation. Connective tissue growth factor (CTGF; also known as CCN2), is found in high levels in OA chondrocytes and is frequently involved in fibrosis, bone formation, and cartilage repair. The present study was therefore undertaken to investigate the potential role of CTGF in OA pathophysiology. We transfected the synovial lining of mouse knee joints with a recombinant adenovirus expressing human CTGF and measured synovial fibrosis and proteoglycan content in cartilage on days 1, 3, 7, 14, and 28. Messenger RNA (mRNA) expression in synovium and cartilage was measured on days 3, 7, and 21. CTGF induced synovial fibrosis, as indicated by accumulation of extracellular matrix and an increase in procollagen type I-positive cells. The fibrosis reached a maximum on day 7 and had reversed by day 28. Levels of mRNA for matrix metalloproteinase 3 (MMP-3), MMP-13, ADAMTS-4, ADAMTS-5, tissue inhibitor of metalloproteinases 1 (TIMP-1), and transforming growth factor beta were elevated in the fibrotic tissue. TIMP-1 expression was elevated on day 3, while expression of other genes did not increase until day 7 or later. CTGF induced proteoglycan depletion in cartilage as early as day 1. Maximal depletion was observed on days 3-7. Cartilage damage was reduced by day 28. A high level of MMP-3 mRNA expression was found in cartilage. CTGF overexpression did not induce osteophyte formation. CTGF induces transient fibrosis that is reversible within 28 days. Overexpression of CTGF in knee joints results in reversible cartilage damage, induced either by the high CTGF levels or via factors produced by the CTGF-induced fibrotic tissue.

Utility of delayed gadolinium-enhanced MRI (dGEMRIC) for qualitative evaluation of articular cartilage of patellofemoral joint

Delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) was used for the measurement of relative proteoglycan depletion of articular cartilage in the patellofemoral (PF) joint following a proprietary protocol, which was compared with the X-ray images, proton density weighted MR images (PDWI) and arthroscopic findings. The study examined 30 knees. The ages ranged from 16 to 74 (average 40.3) years. The Gd-DTPA(2-)containing contrast medium was used in a single dose. The subjects were made to exercise the knee joint for 10 min; and MR images were taken 2 h after intravenous injection of contrast medium. T1-calculated images were produced and the region of interest (ROI) was set as follows. (1) ROI1: entire articular cartilage in a slice through the center of the patella. (2) ROI2: low signal region in T1-calculated images, which were set in a blind fashion by two observers. (3) ROI3: articular cartilage on one side that includes ROI2 where low signal region were detected (medial or lateral). ROI3 was set to examine the contrast of ROI2 with surrounding articular cartilage. The average T1 values of ROI1 was 393.5+/-33.6 ms for radiographic grade 0 and 361.3+/-11.1 ms for grade I, which showed a significant difference (P=0.036). The T1 value of ROI2 was 351.6+/-28.2 ms for grade I, 361.9+/-38.3 ms for grade II, 362.1+/-67.7 ms for grade III, and 297.8+/-54.1 ms for grade IV according to arthroscopic Outerbridge classification. All cases, that demonstrated decrease of T1 values on dGEMRIC (ROI2), showed abnormal arthroscopic or direct viewing findings. The ratio (ROI3/ROI2) in cases of only slight damage classified as Outerbridge grade I (6 cases) was an average of 1.04+/-0.02 and was 1.0 or greater in all cases, thereby indicating well-defined contrast with the surrounding cartilage. The diagnosis of damage in articular cartilage was possible in all 16 cases with radiographic K-L grade I on dGEMRIC, while the intensity changes were not found in 10 of 16 cases on PDWI. The dGEMRIC with a single-dose would be useful on a diagnosis of the area demonstrating early relative proteoglycan depletion in the articular cartilage of the PF joint prior to any discernible changes in the subchondral bone on X-ray images and exceeds to plain MR images for examining deterioration of articular cartilage.

Characterization of proteoglycan depletion in articular cartilage using two‐dimensional time domain nuclear magnetic resonance

In vitro proteoglycan (PG) depletion in the 20-40% range (enzymatic PG depletion of normal cartilage in the early osteoarthritis (OA) PG depletion range) was investigated in articular cartilage using 2D time domain NMR relaxation techniques. Spin-lattice relaxation times were measured at low fields (T(1rho)) and at high fields (T(1)) using nonselective and selective excitation pulse sequences. The short relaxation time magnetization components in T(1rho) ( approximately 8% signal) and nonselective T(1) ( approximately 5% signal) experiments were significantly altered with PG degradation. In addition, a magnetization component ( approximately 5% signal) with a "fast " T(1) approximately 7 ms was observed in the T(1) experiment involving selective excitation. This fast T(1) was at least 10 times shorter than the short T(1) in the nonselective experiment and was associated with a strong magnetization exchange mechanism between collagen and PG. The results suggest that T(1rho) and T(1) (nonselective and selective) relaxation based MRI techniques, which focus on the short relaxation time magnetization components, have the potential of detecting molecular abnormalities associated with early OA earlier than single, long relaxation time component approaches.

Blocking of Interleukin-17 during Reactivation of Experimental Arthritis Prevents Joint Inflammation and Bone Erosion by Decreasing RANKL and Interleukin-1

Rheumatoid arthritis is characterized by an intermittent course of disease with alternate periods of remission and relapse. T cells, and in particular the T-cell cytokine interleukin-17 (IL-17), are expected to be involved in arthritic flares. Here, we report that neutralizing endogenous IL-17 during reactivation of antigen-induced arthritis prevents joint inflammation and bone erosion. Synovial IL-17 mRNA expression was clearly up-regulated during primary arthritis and was further enhanced after antigen rechallenge. Neutralization of IL-17 significantly prevented joint swelling at day 1 of flare and significantly suppressed joint inflammation and cartilage proteoglycan depletion at day 4, as assessed by histology. Blocking IL-17 also clearly reduced bone erosions. Cathepsin K, a marker of osteoclast-like activity, and synovial RANKL mRNA expression were both suppressed. The degree of bone erosions strongly correlated with the severity of joint inflammation, suggesting that anti-IL-17 treatment reduced bone erosion by suppressing joint inflammation. Interestingly, blocking IL-17 suppressed synovial expression of both IL-1beta and tumor necrosis factor-alpha, whereas blocking IL-1 did not affect tumor necrosis factor-alpha levels. These data indicate that IL-17 is an important upstream mediator in joint pathology during flare-up of experimental arthritis.