Serum keratan sulfate transiently increases in the early stage of osteoarthritis during strenuous running of rats: protective effect of intraarticular hyaluronan injection

Impact of treadmill running on distal femoral cartilage thickness: a cross-sectional study of professional athletes and healthy controls

PURPOSE

This present study aimed to assess the impact of treadmill running on distal femoral cartilage thickness.

METHODS

Professional athletes aged 20 to 40 years with a history of treadmill running (minimum 75 min per week for the past three months or more) and age-, sex-, and body mass index (BMI)-matched healthy controls were recruited. Demographics and clinical features of participants were recorded. Athletes were divided into subgroup 1 with less than 12 months of treadmill running and subgroup 2 with 12 months or more of treadmill running. Distal femoral cartilage thicknesses were measured at the midpoints of the right medial condyle (RMC), right intercondylar area (RIA), right lateral condyle (RLC), left medial condyle (LMC), left intercondylar area (LIA), and left lateral condyle (LLC) via ultrasonography.

RESULT

A total of 72 athletes (mean age: 29.6 ± 6.6 years) and 72 controls (mean age: 31.9 ± 6.7 years) were enrolled. Athletes had significantly thinner cartilages in the RLC (2.21 ± 0.38 vs. 2.39 ± 0.31 cm, p = 0.002), LLC (2.28 ± 0.37 vs. 2.46 ± 0.35 cm, p = 0.004), and LMC (2.28 ± 0.42 vs. 2.42 ± 0.36 cm, p = 0.039) compared with the control group. Furthermore, cartilage thickness was significantly thinner in subgroup 2 athletes compared with the control group in the RLC (2.13 ± 0.34 vs. 2.39 ± 0.31 cm, p = 0.001), LLC (2.22 ± 0.31 vs. 2.46 ± 0.35 cm, p = 0.005), and LMC (2.21 ± 0.46 vs. 2.42 ± 0.36 cm, p = 0.027); however, subgroup 1 athletes did not have such differences. There was a weak negative correlation between total months of treadmill running and cartilage thickness in the RLC (r = - 0.0236, p = 0.046) and LLC (r = - 0.0233, p = 0.049). No significant correlation was found between the distal femoral cartilage thickness at different sites and the patients' demographic features, including age, BMI, speed and incline of treadmill running, and minutes of running per session and week (p > 0.05).

CONCLUSION

Compared with healthy controls, professional athletes with a history of long-term high-intensity treadmill running had thinner femoral cartilages. The duration (months) of treadmill running was weakly negatively correlated with distal femoral cartilage thickness. Longitudinal studies with prolonged follow-ups are needed to clarify how treadmill running affects femoral cartilage thickness in athletes.

Mild treadmill exercise inhibits cartilage degeneration via macrophages in an osteoarthritis mouse model

Objective

We previously reported how treadmill exercise can suppress cartilage degeneration. Here, we examined the changes in macrophage dynamics in knee osteoarthritis (OA) during treadmill exercise and the effect of macrophage depletion.

Design

OA mouse model, generated via anterior cruciate ligament transection (ACLT), was subjected to treadmill exercise of different intensities to investigate the effects on cartilage and synovium. In addition, clodronate liposomes, which deplete macrophages, were injected intra-articularly into the joint to examine the role of macrophages during treadmill exercise.

Results

Cartilage degeneration was delayed by mild exercise, and concomitantly, an increase in anti-inflammatory factors in the synovium was observed, with a decrease in the M1 and increase in M2 macrophage ratio. On the contrary, high-intensity exercise led to the progress of cartilage degeneration and was associated with an increase in the M1 and a decrease in the M2 macrophage ratio. The clodronate liposome-induced reduction of synovial macrophages delayed cartilage degeneration. This phenotype was reversed by simultaneous treadmill exercise.

Conclusions

Treadmill exercise, especially at high intensity, was detrimental to articular cartilage, whereas mild exercise reduced cartilage degeneration. Moreover, M2 macrophage response appeared necessary for the chondroprotective effect of treadmill exercise. This study indicates the importance of a more comprehensive analysis of the effects of treadmill exercise, not limited to the mechanical stress added directly to cartilage. Hence, our findings might help determine the type and intensity of prescribed exercise therapy for patients with knee OA.

The protective effect of mangiferin on osteoarthritis: An in vitro and in vivo study

Mangiferin is a kind of polyphenol chemical compound separated from these herbal medicines of Mangifera indica L., Anemarrhena asphodeloides Bge. and Belamcanda chinensis L., which has anti-inflammatory, anti-virus, and other physiological activities without toxic effects. Osteoarthritis (OA) is a chronic disease that is also a kind of arthritis disease in which articular cartilage or bones under the joint is damaged. In addition, artificial replacements are required in severe cases. At present, there are not too much researches on the potential biological activities of mangiferin that plays a protective role in the treatment of OA. In this study, we evaluated the protective effect of mangiferin on osteoarthritis (OA) in vitro and in vivo. First, the effect of different concentrations of mangiferin on rat chondrocytes was determined by MTT assay. Second, the effects of mangiferin on the expression levels of matrix metalloproteinase (MMP)-13, TNF alpha, Collagen II, Caspase-3, and cystatin-C in interleukin-1beta (IL-1beta)-induced rat chondrocytes were examined by the real-time polymerase chain reaction in vitro, meanwhile the effects of mangiferin on the nuclear factor kappa-B (NF-kappaB) signaling pathway were also investigated by Western Blot. Finally, the anti-osteoarthritic protective effect of mangiferin was evaluated in the rat model by anterior cruciate ligament transection (ACLT) combined with bilateral ovariectomy-induced OA in vivo. The results showed that the mangiferin was found to inhibit the expression of MMP-13, TNF-alpha, and Caspase-3 which also increased the expression of Collagen II and cystatin-C in IL 1beta induced rat chondrocytes. In addition, IL-1beta-induced activation of nuclear factor kappa-B (NF-kappaB) and the degradation of inhibitor of kappaB (IkappaB)-alpha were suppressed by mangiferin. For the in vivo study in a rat model of OA, 100 microl of mangiferin was administered by intra-articular injections for rats, the results showed that the cartilage degradation was suppressed by mangiferin through Micro CT and Histological Examination. According to both in vitro and in vivo results, mangiferin has a protective effect in the treatment of OA which may be a promising therapeutic agent for OA.

Impact of Controlling Abnormal Joint Movement on the Effectiveness of Subsequent Exercise Intervention in Mouse Models of Early Knee Osteoarthritis

OBJECTIVE

Moderate mechanical stress is necessary for preserving the cartilage. The clinician empirically understands that prescribing only exercise will progress osteoarthritis (OA) for knee OA patients with abnormal joint movement. When prescribing exercise for OA, we hypothesized that degeneration of articular cartilage could be further prevented by combining interventions with the viewpoint of normalizing joint movement.

DESIGN

Twelve-week-old ICR mice underwent anterior cruciate ligament transection (ACL-T) surgery in their right knee and divided into 4 groups: ACL-T, controlled abnormal joint movement (CAJM), ACL-T with exercise (ACL-T/Ex), CAJM with exercise (CAJM/Ex). Animals in the walking group were subjected to treadmill exercise 6 weeks after surgery, which included walking for 18 m/min, 30 min/d, 3 d/wk for 4 weeks. Joint instability was measured by anterior drawer test, and safranin-O staining and immunohistochemical staining were performed.

RESULTS

OARSI (Osteoarthritis Research Society International) score of ACL-T/Ex group showed highest among 4 groups (P < 0.001). And CAJM/Ex group was lower than ACL-T/Ex group. Positive cell ratio of IL-1β and MMP-13 in CAJM/Ex group was lower than ACL-T/Ex group (P < 0.05).

CONCLUSIONS

We found that the state of the intra-articular environment can greatly influence the effect of exercise on cartilage degeneration, even if exercise is performed under the same conditions. In the CAJM/Ex group where joint movement was normalized, abnormal mechanical stress such as shear force and compression force accompanying ACL cutting was alleviated. These findings may highlight the need to consider an intervention to correct abnormal joint movement before prescribing physical exercise in the treatment of OA.

Hyperglycemia-induced accumulation of advanced glycosylation end products in fibroblast-like synoviocytes promotes knee osteoarthritis

Osteoarthritis (OA) is significantly associated with diabetes, but how hyperglycemia induces or aggravates OA has not been shown. The synovium plays a critical role in cartilage metabolism and substance exchange. Herein, we intended to investigate whether and how hyperglycemia affects the occurrence and progression of OA by influencing the synovium. In patients with knee OA and diabetes (DM OA), we found a more severe inflammatory response, higher endoplasmic reticulum stress (ERS) levels, and more advanced glycosylation end products (AGEs) accumulation in the synovium than in patients without diabetes. Subsequently, we found similar results in the DM OA group in a rat model. In the in vitro cocultivation system, high glucose-stimulated AGEs accumulation, ERS, and inflammation in rat fibroblast-like synoviocytes (FLSs), which resulted in chondrocyte degeneration due to inflammatory factors from FLSs. Furthermore, in the synovium of the DM OA group and FLSs treated with high glucose, the expression of glucose transporter 1 (GLUT1) and its regulatory factor hypoxia-inducible factor (HIF)-1α was increased significantly. Inhibitors of HIF-1α, GLUT1 or AGEs receptors attenuated the effect of high glucose on chondrocyte degradation in the FLS-chondrocyte coculture system. In summary, we demonstrated that hyperglycemia caused AGEs accumulation in FLSs via the HIF-1α-GLUT1 pathway, which increases the release of inflammatory factors from FLSs, subsequently inducing chondrocyte degradation and promoting OA progression.

Reduced PDGF-AA in subchondral bone leads to articular cartilage degeneration after strenuous running

To identify the effects of running on articular cartilage and subchondral bone remodeling, C57BL/6 mice were randomly divided into three groups: control, moderate-, and strenuous running. Magnetic resonance imaging showed bone marrow lesions in the knee subchondral bone in the strenuous-running group in contrast with the other two groups. The microcomputed tomography analysis showed promoted bone formation in the subchondral bone in mice subjected to strenuous running. Histological and immunohistochemistry results indicated that terminal differentiation of chondrocytes and degeneration of articular cartilage were enhanced but, synthesis of platelet-derived growth factor-AA (PDGF-AA) in the subchondral bone was suppressed after strenuous running. In vitro, excessive mechanical treatments suppressed the expression of PDGF-AA in osteoblasts, and the condition medium from mechanical-treated osteoblasts stimulated maturation and terminal differentiation of chondrocytes. These results indicate that strenuous running suppresses the synthesis of PDGF-AA in subchondral bone, leading to downregulated PDGF/Akt signal in articular cartilage and thus cartilage degeneration.

Activation of the renin-angiotensin system in mice aggravates mechanical loading-induced knee osteoarthritis

Epidemiological studies have shown an association between hypertension and knee osteoarthritis (OA). The purpose of this study was to investigate whether activation of the renin–angiotensin system (RAS) can aggravate mechanical loading-induced knee OA in mice. Eight-week-old male Tsukuba hypertensive mice (THM) and C57BL/6 mice were divided into four groups: i) running THM group, ii) running C57BL/6 mice group, iii) non-running THM group, and iv) non-running C57BL/6 mice group. Mice in the running group were forced to run (25 m/min, 30 min/day, 5 days/week) on a treadmill. All mice in the four groups (n=10 in each group) were euthanized after 0, 2, 4, 6, or 8 weeks of running or natural breeding. Cartilage degeneration in the left knees was histologically evaluated using the modified Mankin score. Expression of Col X, MMP-13, angiotensin type 1 receptor (AT1R), and AT2R was examined immunohistochemically. To study the effects of stimulation of the AT1R in chondrocytes by mechanical loading and/or Angiotensin II (AngII) on transduction of intracellular signals, phosphorylation levels of JNK and Src were measured in bovine articular chondrocytes cultured in three-dimensional agarose scaffolds. After 4 weeks, the mean Mankin score for the lateral femoral condylar cartilage was significantly higher in the THM running group than in the C57BL/6 running group and non-running groups. AT1R and AT2R expression was not detected at 0 weeks in any group but was noted after 4 weeks in the THM running group. AT1R expression was also noted at 8 weeks in the C57BL/6 running group. The expression levels of AT1R, COL X, and MMP-13 in chondrocytes were significantly higher in the THM running group than in the control groups. Positive significant correlations were noted between the Mankin score and the rate of AT1R-immunopositive cells, between the rates of AT1R- and Col X-positive cells, and between the rates of AT1Rand AT2R-positive cells. The phosphorylation level of JNK was increased by cyclic compression loading or addition of AngII to the cultured chondrocytes and was reversed by pretreatment with an AT1R blocker. A synergistic effect on JNK phosphorylation was observed between compression loading and AngII addition. Transgene activation of renin and angiotensinogen aggravated mechanical load-induced knee OA in mice. These findings suggest that AT1R expression in chondrocytes is associated with early knee OA and plays a role in the progression of cartilage degeneration. The RAS may be a common molecular mechanism involved in the pathogenesis of hypertension and knee OA.

Prenatal caffeine exprosure increases adult female offspring rat's susceptibility to osteoarthritis via low-functional programming of cartilage IGF-1 with histone acetylation

Our previous in vivo studies showed that prenatal caffeine exposure (PCE) could restrain the development of chondrogenesis, which may delay fetal articular cartilage development and increase susceptibility to osteoarthritis in adults. So, the goal of the current study is to clarify theincreasing susceptibility to adult osteoarthritis in caffeine-exposed female offspring and its'mechanism. Pregnant rats were treated with 120 mg/kg·d caffeine or equal volumes of saline from gestational day (GD) 9 to 20. knee joints were collected from GD20 female fetuses and 18-week old female offspring which was treated with strenuous running for 6 weeks (55 min/day at 20 m/min) load to induce osteoarthritis. Knee joints from GD20 fetuses and adult offspring were collected for histochemistry and immunohistochemistry. Next, chondrocytes were isolated from 1-day-old newborn rats and in vitro studies were conducted where the cells in primary culture were exposed to 1, 10, and 100 μM caffeine and 250, 500, and 1,250 nM corticosterone. Insulin-like growth factor 1 (IGF-1) signal pathway genes' expression levels in fetal chondrocytes were studied, and IGF-1 histone acetylation was detected in vitro. Immunohistochemical results showed low expression levels of IGF-1 signaling genes (IGF-1, IRS-1, AKT, and COL2A1) both in fetal and adult cartilage with PCE. For adult offspring, histological results and Mankin score revealed increased cartilage destruction and accelerated osteoarthritis progression in PCE group with strenuous running exercise. Analysis in vitro revealed that caffeine and corticosterone impeded the expression of IGF-1 signaling pathway aggrecan and COL2A1 genes, but only corticosterone decreased H3K9 and H3K27 acetylation in the IGF-1 promoter region. In concluson, PCE low functional programmed cartilage IGF-1 by histone acetylation modification via overexposure to corticosterone and delayed articular cartilage development from fetus to adults. Then, the delayed cartilage development increased susceptibility to osteoarthritis in offsprings.

Early Signs of Bone and Cartilage Changes Induced by Treadmill Exercise in Rats

This study aims to investigate the earliest alterations of bone and cartilage tissues as a result of different exercise protocols in the knee joint of Wistar rats. We hypothesize that pretraining to a continuous intense running protocol would protect the animals from cartilage degeneration. Three groups of animals were used: (i) an adaptive (pretraining) running group that ran for 8 weeks with gradually increasing velocity and time of running followed by a constant running program (6 weeks of 1.12 km/hour running per day); (ii) a non-adaptive running (constant running) group that initially rested for 8 weeks followed by 6 weeks of constant running; and (iii) a non-running (control) group. At weeks 8, 14, and 20 bone and cartilage were analyzed. Both running groups developed mild symptoms of cartilage irregularities, such as chondrocyte hypertrophy and cell clustering in different cartilage zones, in particular after the adaptive running protocol. As a result of physical training in the adaptive running exercise a dynamic response of bone was detected at week 8, where bone growth was enhanced. Conversely, the thickness of epiphyseal trabecular and subchondral bone (at week 14) was reduced due to the constant running in the period between 8 and 14 weeks. Finally, the intermediate differences between the two running groups disappeared after both groups had a resting period (from 14 to 20 weeks). The adaptive running group showed an increase in aggrecan gene expression and reduction of MMP2 expression after the initial 8 weeks running. Thus, the running exercise models in this study showed mild bone and cartilage/chondrocyte alterations that can be considered as early-stage osteoarthritis. The pretraining adaptive protocol before constant intense running did not protect from mild cartilage degeneration. © 2017 The Authors. JBMR Plus is published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

Review of the Mechanism of Action for Supartz FX in Knee Osteoarthritis

Objective Summarize the biologic effects of Supartz FX for knee osteoarthritis (OA), the first worldwide clinically approved intra-articular (IA) hyaluronic acid (HA) product. Design To determine the mechanism of action from preclinical and clinical studies, a literature search was conducted of Supartz FX using academic databases from 1987 to 2016. Articles on Supartz FX that deal with its mechanisms of action were extracted, categorized, and reviewed. Results Supartz FX has 2 potential mechanisms of action: (1) biomechanical: IA Supartz FX directly improves the viscoelasticity and lubrication of synovial fluid; (2) physiologic: IA Supartz FX penetrates synovium and cartilage tissues to reach HA receptors on the surface of synoviocytes and chondrocytes. In synovium, suppression of gene expression in inflammatory mediators results in improved endogenous HA production, improved properties of synovial fluid, and reduction in pain. In cartilage, suppression of gene expression of collagenases and aggrecanases suppresses cartilage degeneration. Conclusion The net results of basic and clinical studies is that IA Supartz FX provides a more favorable biomechanical and functional environment in the knee joint. Hence, it is not only a lubricant but is also physiologically active. These actions may help explain both short- and long-term improvement in pain and function often achieved from IA Supartz FX in knee OA.

Morphological and Microstructural Alterations of the Articular Cartilage and Bones during Treadmill Exercises with Different Additional Weight-Bearing Levels

The aim of this study was to investigate the morphological and microstructural alterations of the articular cartilage and bones during treadmill exercises with different exercise intensities. Sixty 5-week-old female rats were randomly divided into 10 groups: five additional weight-bearing groups (WBx) and five additional weight-bearing with treadmill exercise groups (EBx), which were subjected to additional weight bearing of x% (x = 0, 5, 12, 19, and 26) of the corresponding body weight of each rat for 15 min/day. After 8 weeks of experiment, the rats were humanely sacrificed and their bilateral intact knee joints were harvested. Morphological analysis of the cartilages and microcomputed tomography evaluation of bones were subsequently performed. Results showed that increased additional weight bearing may lead to cartilage damage. No significant difference was observed among the subchondral cortical thicknesses of the groups. The microstructure of subchondral trabecular bone of 12% and 19% additional weight-bearing groups was significantly improved; however, the WB26 and EB26 groups showed low bone mineral density and bone volume fraction as well as high structure model index. In conclusion, effects of treadmill exercise on joints may be associated with different additional weight-bearing levels, and exercise intensities during joint growth and maturation should be selected reasonably.

Impact of a daily exercise dose on knee joint cartilage - a systematic review and meta-analysis of randomized controlled trials in healthy animals

OBJECTIVE

To investigate the impact of a daily exercise dose on cartilage composition and thickness, by conducting a systematic review of randomized controlled trials (RCTs) involving healthy animals.

METHODS

A narrative synthesis of the effect of a daily exercise dose on knee cartilage aggrecan, collagen and thickness was performed. A subset of studies reporting sufficient data was combined in meta-analysis using a random-effects model. Meta-regression analyses were performed to investigate the impact of covariates.

RESULTS

Twenty-nine RCTs, involving 64 comparisons, were included. In the low dose exercise group, 21/25 comparisons reported decreased or no effect on cartilage aggrecan, collagen and thickness. In the moderate dose exercise group, all 12 comparisons reported either no or increased effect. In the high dose exercise group, 19/27 comparisons reported decreased effect. A meta-analysis of 14 studies investigating cartilage thickness showed no effect in the low dose exercise group (SMD -0.02; 95% CI -0.42 to 0.38; I² = 0.0%), large but non-significant cartilage thickening in the moderate dose exercise group (SMD 0.95; 95% CI -0.33 to 2.23; I² = 72.1%) and non-significant cartilage thinning in the high dose exercise group (SMD -0.19; 95% CI -0.49 to 0.12; I² = 0.0%). Results were independent of analyzed covariates. The overall quality of the studies was poor because of inadequate reporting of data and high risk of bias.

CONCLUSIONS

Our results suggest that the relationship between daily exercise dose and cartilage composition, but not necessarily cartilage thickness, may be non-linear. While we found inconclusive evidence for a low daily dose of exercise, a high daily dose of exercise may have negative effects and a moderate daily dose of exercise may have positive effects on cartilage matrix composition in healthy animals.

Appropriate Use Criteria for Hyaluronic Acid in the Treatment of Knee Osteoarthritis in the United States

OBJECTIVE

A workgroup of clinical experts has developed an Appropriate Use Criteria (AUC) for the use of hyaluronic acid (HA) in the treatment of osteoarthritis (OA) of the knee. The increasingly broad and varied use of HA injections, lack of published clinical guidance, and limited coverage for their use has created the imperative to establish appropriateness criteria.

METHODS

The experts of this workgroup represent rheumatology, orthopedic surgery, physiatry, sports medicine, and nursing clinicians with substantive knowledge of intra-articular HA therapy. This workgroup utilized the results of a systematic review of evidence, expert clinical opinion, and current evidence-based clinical practice guidelines to develop appropriateness criteria for the use of intra-articular HA for knee OA in 17 real-world clinical scenarios.

RESULTS

The workgroup scored the appropriateness of treatment of each patient scenario using a 9-point scale to designate a treatment as appropriate (7-9), uncertain (4-6), or inappropriate (1-3). Six scenarios were scored as appropriate, 10 scenarios were scored as uncertain, and 1 scenario was scored as inappropriate.

CONCLUSION

This article can assist clinicians in shared decision-making by providing best practices in considering HA injections for knee OA treatment. Moreover, this AUC article can aid payers and policy makers in determining reimbursement and preauthorization policies and more appropriately managing health care resources. It is clear that further research is still necessary-particularly in patient populations differentiated by OA severity-that may benefit the greatest from the use of HA injections for the treatment of knee OA.

Photobiomodulation therapy associated with treadmill training in the oxidative stress in a collagen-induced arthritis model

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by chronic and systemic inflammation, which leads to the destruction of the cartilage and bone and affects tissues in multiple joints. Oxidative stress has been implicated with regards to involvement in various disease conditions, such as diabetes mellitus and neurodegenerative, respiratory, cardiovascular, and RA diseases. In vivo experimental studies using photobiomodulation therapy (PBMT) have shown positive effects in reducing lipid peroxidation and in increasing antioxidant activity. The regular practice of physical exercise has also been reported to be a beneficial treatment capable of reducing oxidative damage. Thus, the aim of this study was to analyze the effects of photobiomodulation therapy at 2- and 4-J doses associated with physical exercise on oxidative stress in an experimental model of RA in protein expression involving superoxide dismutase (SOD), glutathione peroxidase (GPX), and/or catalase (CAT) on thiobarbituric acid reactive substances (TBARS). In this study, 24 male Wistar rats divided into four groups were submitted to an RA model (i.e., collagen-induced arthritis, CIA), with the first immunization performed at the base of the tail on days 0 and 7 were included. After 28 days, a third intraarticular dose was administered in both knees of the animals. After the last induction, PBMT was started immediately, transcutaneously at two points (i.e., the medial and lateral), with a total of 15 applications. Treadmill exercise was also started the day after the last induction, and lasted for 5 weeks. With respect to results, we obtained the decreases in the lipid peroxidation and the increases of the antioxidant activities of SOD, GPX and CAT, with physical exercise associated to PBMT in doses of 2 and 4 J. In conclusion, physical exercise associated with PBMT decreases lipid peroxidation and increases antioxidant activity.

Evaluation of the effect of oral administration of collagen peptides on an experimental rat osteoarthritis model

Collagen is an extracellular matrix protein present in the skin, tendon, cartilage and bone. Collagen peptides (CP) are produced by the hydrolysis of gelatin (heat-denatured collagen) by proteases and are utilized as a component of nutraceuticals. The current study investigated the effect of CP on the articular cartilage of OA by evaluating the serum levels of biomarkers (CTX-II for type II collagen degradation and CPII for type II collagen synthesis), histopathological changes (Mankin score, based on the toluidine blue staining of proteoglycans), and immunohistochemical staining of matrix metalloproteinase (MMP)-13 and type II collagen, using a rat experimental osteoarthritis (OA) model. Anterior cruciate ligament transection (ACLT) was performed on the right knee joint to surgically induce OA. Animals were divided into four groups: Control group (Control), sham-operated group (Sham), ACLT group without collagen peptide (ACLT group) and ACLT group with oral administration of CP (CP group). ACLT induced histological damages and significantly increased the Mankin score (P<0.05). However, CP administration markedly suppressed the Mankin score, although this difference was not significant. In addition, serum CTX-II levels were significantly decreased in CP group compared with those in the ACLT group (P<0.05). By contrast, serum CPII levels did not differ significantly among the four groups. Moreover, immunohistochemical staining of type II collagen and MMP-13 (an important type II collagen-degrading enzyme) indicated that the amount of type II collagen increased, whereas the number of MMP-13 positive chondrocytes decreased in the CP group compared with ACLT group. These observations suggest that CP has the potential to exert chondroprotective action on OA by inhibiting MMP-13 expression and type II collagen degeneration.

Strenuous running exacerbates knee cartilage erosion induced by low amount of mono-iodoacetate in rats

Background

It is still debated whether strenuous running in the inflammatory phase produces beneficial or harmful effect in rat knees. We examined (1) the dropout rate of rats during a 30-km running protocol, (2) influences of strenuous running and/or low amounts of mono-iodoacetate injection on cartilage, and (3) the effect of strenuous running on synovitis.

Methods

Rats were forced to run 30 km over 6 weeks and the dropout rate was examined. One week after 0.1 mg mono-iodoacetate was injected into the right knee, rats were forced to run either 15 km or not run at all over 3 weeks, after which knee cartilage was evaluated. Synovium at the infrapatellar fat pad was also examined histologically.

Results

Even though all 12 rats run up to 15 km, only 6 rats completed 30 km of running. Macroscopically, 0.1 mg mono-iodoacetate induced erosion at the tibial cartilage irrespective of 15 km of running. Histologically, 0.1 mg mono-iodoacetate induced loss of cartilage matrix in the tibial cartilage, and an additional 15 km of strenuous running significantly exacerbated the loss. Synovitis caused by mono-iodoacetate improved after running.

Conclusions

Only 50% of rats completed 30 km of running because of foot problems. Strenuous running further exacerbated tibial cartilage erosion but did not influence synovitis induced by mono-iodoacetate.

Prenatal ethanol exposure increases osteoarthritis susceptibility in female rat offspring by programming a low-functioning IGF-1 signaling pathway

Epidemiological evidence indicates that osteoarthritis (OA) and prenatal ethanol exposure (PEE) are both associated with low birth weight but possible causal interrelationships have not been investigated. To investigate the effects of PEE on the susceptibility to OA in adult rats that experienced intrauterine growth retardation (IUGR), and to explore potential intrauterine mechanisms, we established the rat model of IUGR by PEE and dexamethasone, and the female fetus and 24-week-old adult offspring subjected to strenuous running for 6 weeks were sacrificed. Knee joints were collected from fetuses and adult offspring for histochemistry, immunohistochemistry and qPCR assays. Histological analyses and the Mankin score revealed increased cartilage destruction and accelerated OA progression in adult offspring from the PEE group compared to the control group. Immunohistochemistry showed reduced expression of insulin-like growth factor-1 (IGF-1) signaling pathway components. Furthermore, fetuses in the PEE group experienced IUGR but exhibited a higher postnatal growth rate. The expression of many IGF-1 signaling components was downregulated, which coincided with reduced amounts of type II collagen in the epiphyseal cartilage of fetuses in the PEE group. These results suggest that PEE enhances the susceptibility to OA in female adult rat offspring by down-regulating IGF-1 signaling and retarding articular cartilage development.

Effects of high molecular weight hyaluronic acid on induced arthritis of the temporomandibular joint in rats

High molecular weight hyaluronic acid (HMWHA) has been used to treat temporomandibular joint (TMJ) disorders, but controversial results have been described. This study aimed to characterize the morphological and biochemical actions of HMWHA on induced arthritis of the TMJ. Twenty-four male Wistar rats were used, and arthritis of the TMJ was induced through an intra-articular injection of Complete Freund's Adjuvant (CFA) (50 μl). One week after arthritis induction, the animals were treated with HMWHA (once per week for three weeks). Histological analyses were performed using sections stained with hematoxylin-eosin, toluidine blue and Picrosirius. Were also performed histomorphometric analysis and birefringence of collagenous fibers (polarization microscopy). Biochemical analyses of TMJ tissues were carried out through measurements of sulfated glycosaminoglycans and zymography for evaluation of metalloproteinase-2 and -9 (MMP-2 and -9). Data were analyzed using paired t-test and unpaired t-test, with a 5% significance level. HMWHA reduced histologic changes and thickness of the articular disc, led to a greater arrangement of collagenous fibers, lower concentration of sulfated glycosaminoglycans and lower activity in all isoforms of MMP-2 and -9 in TMJs with induced arthritis. These findings suggest that HMWHA may exert a protective effect on the TMJ.

The beneficial effects of exercise on cartilage are lost in mice with reduced levels of ECSOD in tissues

Osteoarthritis (OA) is associated with increased mechanical damage to joint cartilage. We have previously found that extracellular superoxide dismutase (ECSOD) is decreased in OA joint fluid and cartilage, suggesting oxidant damage may play a role in OA. We explored the effect of forced running as a surrogate for mechanical damage in a transgenic mouse with reduced ECSOD tissue binding. Transgenic mice heterozygous (Het) for the human ECSOD R213G polymorphism and 129-SvEv (wild-type, WT) mice were exposed to forced running on a treadmill for 45 min/day, 5 days/wk, over 8 wk. At the end of the running protocol, knee joint tissue was obtained for histology, immunohistochemistry, and protein analysis. Sedentary Het and WT mice were maintained for comparison. Whole tibias were studied for bone morphometry, finite element analysis, and mechanical testing. Forced running improved joint histology in WT mice. However, when ECSOD levels were reduced, this beneficial effect with running was lost. Het ECSOD runner mice had significantly worse histology scores compared with WT runner mice. Runner mice for both strains had increased bone strength in response to the running protocol, while Het mice showed evidence of a less robust bone structure in both runners and untrained mice. Reduced levels of ECSOD in cartilage produced joint damage when joints were stressed by forced running. The bone tissues responded to increased loading with hypertrophy, regardless of mouse strain. We conclude that ECSOD plays an important role in protecting cartilage from damage caused by mechanical loading.

Serum CTXii Correlates With Articular Cartilage Degeneration After Anterior Cruciate Ligament Transection or Arthrotomy Followed by Standardized Exercise

Background:

Anterior cruciate ligament injury increases risk for accelerated development of osteoarthritis. The effect of exercise on articular cartilage following joint injury is not well understood. Biochemical biomarkers of collagen degradation and proteoglycan turnover are potential indicators for early articular cartilage degeneration.

Hypothesis:

This study tests the hypothesis that serum concentrations of CS846 and CTXii correlate with structural changes to articular cartilage following joint injury in exercised animals.

Study Design:

Controlled laboratory study.

Methods:

Twenty-four Sprague-Dawley rats underwent either arthrotomy alone (sham surgery) or anterior cruciate ligament transection (ACLT). Animals were recovered for 3 weeks and then exercised on a treadmill at 18 m per minute, 1 hour per day, 5 days per week, until sacrifice either 6 or 12 weeks later. Articular cartilage was assessed grossly, and histology was graded using modified Mankin, toluidine blue, and modified David-Vaudey scales. Serum collected preoperatively and at sacrifice was assayed by ELISA for CTXii and CS846.

Results:

At 6 weeks, gross grades (P < 0.01), modified Mankin scores (P < 0.03), and toluidine blue scores (P < 0.04) were higher, reflecting increased degeneration in ACLT animals compared with sham surgery animals. Serum CS846 increased after 6 weeks in ACLT animals (P < 0.05). Serum CTXii levels strongly correlated with Mankin degenerative scores (coefficient = 0.81, P < 0.01) and David-Vaudey histology grades (coefficient = 0.73, P < 0.01) at 6 weeks. While gross grades remained higher at 12 weeks in ACLT animals (P < 0.04), no differences were seen in serum CS846 and CTXii. Histology scores also showed no differences between ACLT and sham due to increasing degeneration in the sham surgery group.

Conclusion:

The strong correlation between serum CTXii and microstructural changes to articular cartilage following joint injury demonstrates potential use of serum biomarkers for early detection of cartilage degeneration. Increasing cartilage degeneration in exercised sham-surgery animals suggests that early loading may have negative effects on articular cartilage due to either mechanical injury or hemarthrosis after arthrotomy.

Clinical Relevance:

Patients with anterior cruciate ligament injury are at increased risk for development of posttraumatic osteoarthritis. CTXii may be useful for early detection of joint degeneration. Further study on the effects of exercise after injury is important to postinjury and postoperative rehabilitation.

Raman spectroscopy detection of molecular changes associated with two experimental models of osteoarthritis in rats

The aim of the present study was to evaluate the feasibility of applying Raman spectroscopy in probing the molecular changes in terms of collagen deposition and tissue remodeling associated with two well-established experimental models of osteoarthritis (OA) in knee of rats. In order to evaluate alterations in the articular surface area, the menisci-covered tibial region was assessed into three groups as follows: control (joint preserved) and two models of experimental knee OA: collagenase-induced model (n = 8) and treadmill exercise-induced model (n = 8). Each group was examined for molecular changes using spectral parameters related to cartilage, subchondral bone, and bone tissues. A significant increase of Raman ratios related to mineralization and tissue remodeling was found (p < 0.05), suggesting that both models were successful for inducing OA in rats. The significantly lower phenylalanine content and higher crystallinity in the treadmill exercise-induced model of OA than collagenase-induced model of OA (p < 0.05) indicated that the OA pathogenesis was model-dependent. Thus, this work suggests that the Raman spectroscopy technique has potential for the diagnosis and detection of cartilage damage and monitoring of subchondral bone and bone in OA pathogenesis at the molecular level.

Gradual strenuous running regimen predisposes to osteoarthritis due to cartilage cell death and altered levels of glycosaminoglycans

OBJECTIVE

To investigate the hypothesis that strenuous running is a predisposing factor for osteoarthritis.

DESIGN

Wistar rats were divided into two groups: a control group (CG) and a trained group (TG). The TG underwent a strenuous treadmill running training regimen of controlled intensity, exhibiting progressively improvement of fitness over 12 weeks, running at least 55 km during this period and finally performing an ultra-endurance running exercise to exhaustion. After this period, rats from both groups were euthanized and their knees removed. The articular cartilage was dissected and submitted to histomorphometrical, histomorphological, and immunohistochemical analyses evaluating cell death pathway (caspase-3 and terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL)) and inflammatory cytokines [interleukin-1α (IL-1α) and tumor necrosis factor-α (TNF-α)]. In addition, the tissues were analyzed regarding the types and the content of glycosaminoglycans.

RESULTS

The TG knee joints exhibited increase in the number of chondrocytes and chondrocyte clusters, as well as significantly increased levels of caspase-3, a protein involved in apoptosis, and of inflammatory cytokines IL-1α and TNF-α. In addition, histologically higher grades of osteoarthritis (Osteoarthritis Research Society International - OARSI grading), and significantly decreased levels of chondroitin sulfate and hyaluronic acid. Knee cartilage thickness and TUNEL did not significantly differ between the two groups.

CONCLUSIONS

The articular cartilage of rats subjected to a strenuous running regimen of controlled intensity exhibited molecular and histological characteristics that are present in osteoarthritis.

Intensity-dependent effect of treadmill running on knee articular cartilage in a rat model

OBJECTIVE

To understand the changes of femoral cartilage in response to treadmill running with different intensities in the hope of differentiating "moderate" and "strenuous" running in a rat model.

METHOD

A total of 24 male Wistar rats were randomly assigned into groups of sedentary (SED), low-intensity running (LIR), medium-intensity running (MIR), and high-intensity running (HIR). Rats in LIR, MIR, and HIR groups underwent 8 weeks' treadmill running programs. After sacrificed, femoral condyles were collected to take histomorphometric analysis and immunohistochemistry for collagen II.

RESULTS

Gross and histological observation showed osteoarthritic changes in group HIR. In comparison to SED group, there was significant increase in cartilage thickness, number of chondrocytes, and GAG content in groups LIR and MIR. Conversely, decrease in cartilage thickness, chondrocyte number, and GAG content was found in rats of HIR group, without significant difference though. In addition, in comparison to SED group, HIR group exhibited disorganization of collagen fibril and significantly lower content of collagen type II.

CONCLUSION

An intensity-dependent effect was suggested on the articular cartilage. Our results also demonstrated that running with low-to-medium intensity applied in the present study should be regarded as "moderate" running, whereas high-intensity running as "strenuous" running.

Excessive running induces cartilage degeneration in knee joints and alters gait of rats

The goal of this study was to develop an aggressive running regimen for modeling osteoarthritis (OA) in rats. Twelve Wistar rats were randomly placed into either a running group or a non-running group to serve as the control. The running rats used a motorized treadmill to run either 30 km in 3 weeks or 55 km in 6 weeks. Each week, the prints of hind paws were obtained when rats were made to walk through a tunnel. The resulting prints were digitalized for analyses of stride length and step angle. The histology of the knees was examined at 3 and 6 weeks and the OA pathology in the knees was quantified by Mankin's score. Osteoarthritic pathology developed in the knees of the running rats, including decreased proteoglycan content, uneven type II collagen distribution in the cartilage matrix, increased MMP-13 expression, expanded calcified cartilage zone, and clefts and defects in articular cartilage. The pathology worsened from running for 3 to 6 weeks. Gait analysis revealed an inverse correlation between paw angle and the grades of OA pathology. In conclusion, excessive running induces joint degeneration and a unique gait pattern in rats.

Morin exerts antiosteoarthritic properties: an in vitro and in vivo study

Morin is a flavonoid isolated from members of the Moraceae family. Morin has been reported to possess antioxidative and anticarcinogenic activities. However, the antiosteoarthritic properties of morin have not been investigated. In this study, we evaluate the antiarthritic properties of morin through in vitro and in vivo studies. We examined the effects of morin on the expression levels of matrix metalloproteinase (MMP)-3, MMP-13 and tissue inhibitors of metalloproteinase (TIMP)-1 in interleukin-1 β (IL-1 β)-induced rat chondrocytes by realtime polymerase chain reaction and Western blotting. The effects of morin on the phosphorylation of mitogen-activated protein kinases were also investigated. The in vivo antiosteoarthritic effects of morin were evaluated in the rat model of anterior cruciate ligament transection (ACLT)-induced osteoarthritis (OA). We found that morin inhibited the expression of MMP-3 and MMP-13 and increased the expression of TIMP-1 in IL-1 β-induced rat chondrocytes. In addition, morin inhibited IL-1 β-induced phosphorylation of extracellular signal-regulated kinase and p38. For the in vivo study in a rat model of OA induced by ACLT, in which morin was orally administered to rat, the results show that morin suppressed cartilage degradation. Our results suggest that morin may be considered as a possible therapeutic agent for the treatment of OA.

Quantifying osteoarthritic cartilage changes accurately using in vivo microCT arthrography in three etiologically distinct rat models

In vivo microCT arthrography (µCTa) can be used to measure both quantity (volumetric) and quality (glycosaminoglycan content) of cartilage. This study investigated the accuracy of four segmentation techniques to isolate cartilage from µCTa datasets and then used the most accurate one to investigate if the µCTa method could show osteoarthritic changes in rat models during longitudinal follow-up. Volumetric measurements and glycosaminoglycan contents of patellar cartilage from in vivo µCTa-scans were compared with an ex vivo gold standard µCT-scan. Cartilage was segmented with three global thresholds and one local threshold algorithm. Comparisons were made for healthy and osteoarthritic cartilage. Next, three rat models were investigated for 24 weeks using µCTa. Osteoarthritis was induced by injection with a chemical (mono-iodoacetate), a surgical intervention (grooves applied in articular cartilage), and via exercise (strenuous running). After euthanasia, all knee joints were isolated for histology. Local thresholds accurately segmented cartilage from in vivo µCTa scans and best measured cartilage quantity and glycosaminoglycan content. Each of the three osteoarthritic rat models showed a specific pattern of osteoarthritis progression. All µCTa results were comparable to histology. In vivo µCTa is a sensitive technique for imaging cartilage degradation. Local thresholds enhanced the sensitivity of this method and will probably more accurately detect disease-modulating effects from interventional strategies. The data from rat models may serve as a reference for the time sequence of cartilage degeneration during in vivo testing of new strategies in osteoarthritis treatment.

Evaluation of osteoarthritis induced by treadmill-running exercise using the modified Mankin and the new OARSI assessment system

To apply the Osteoarthritis Research Society International (OARSI) assessment system to an osteoarthritis model, 44 Wistar rats were randomized into treadmill-running exercise or control group. At 6, 8, and 10 weeks, medial knee joints were histopathologically evaluated, and aggrecan neoepitope and TUNEL staining were performed. Cartilage changes in exercise group were histopathologically and histochemically compatible with early OA. Total modified Mankin system (MMS) scores were significantly higher at all time points (each P ≤ 0.01) in exercise than in control group. However, only tibial OARSI scores of runners were higher at 10 weeks (P < 0.05), although OARSI scores were found to be significantly correlated with MMS scores. Both total MMS (Spearman's coefficient ρ = 0.786) and OARSI scores (ρ = 0.443 for femoral; ρ = 0.604 for tibial) were significantly associated with the exercise duration. In conclusion, the OARSI system may not be sensitive to early OA changes induced by treadmill exercise.

Low-intensity pulsed ultrasound (LIPUS) increases the articular cartilage type II collagen in a rat osteoarthritis model

In this study, the effect of low-intensity pulsed ultrasound (LIPUS) on cartilage was evaluated in a rat osteoarthritis (OA) model using serum biomarkers such as CTX-II (type II collagen degradation) and CPII (type II collagen synthesis) as well as histological criteria (Mankin score and immunohistochemical type II collagen staining). OA was surgically induced in the knee joint of rats by anterior cruciate/medial collateral ligament transection and medial meniscus resection (ACLT + MMx). Animals were divided into three groups: sham-operated group (Sham), ACLT + MMx group without LIPUS (-LIPUS), and ACLT + MMx group with LIPUS (+LIPUS; 30 mW/cm(2), 20 min/day for 28 days). CTX-II levels were elevated in both -LIPUS and +LIPUS groups compared to that in the Sham group after the operation, but there was no significant difference between +LIPUS and -LIPUS groups, suggesting that LIPUS does not affect the degradation of type II collagen in this model. In contrast, CPII was significantly increased in +LIPUS group compared to -LIPUS and Sham. Moreover, histological damage on the cartilage (Mankin score) was ameliorated by LIPUS, and type II collagen was immunohistochemically increased by LIPUS in the cartilage of an OA model. Of interest, mRNA expression of type II collagen was enhanced by LIPUS in chondrocytes. Together these observations suggest that LIPUS is likely to increase the type II collagen synthesis in articular cartilage, possibly via the activation of chondrocytes and induction of type II collagen mRNA expression, thereby exhibiting chondroprotective action in a rat OA model.

Evaluation of the effect of glucosamine on an experimental rat osteoarthritis model

AIMS

To investigate the in vivo effect of glucosamine on articular cartilage in osteoarthritis (OA), we evaluated serum biomarkers such as CTX-II (type II collagen degradation) and CPII (type II collagen synthesis) as well as histopathological changes (Mankin score, toluidine blue staining of proteoglycans in an experimental OA model using rats.

MAIN METHODS

OA was surgically induced in the knee joint by anterior cruciate ligament transection (ACLT) in rats. Animals were divided into three groups: sham-operated group (Sham), ACLT group without GlcN administration (-GlcN) and ACLT group with oral administration of glucosamine hydrochloride (+GlcN; 1000mg/kg/day for 56days).

KEY FINDINGS

ACLT induced macroscopic erosive changes on the surfaces of articular cartilage and histological damages such as increase of Mankin score. Of note, glucosamine administration substantially suppressed the macroscopic changes, although the effect on Mankin score was not significant. In addition, serum CTX-II levels were elevated in -GlcN group compared to that in Sham group after the operation. Of importance, the increase of CTX-II was significantly suppressed by GlcN administration. Moreover, serum CP-II levels were substantially increased in +GlcN group compared to those in Sham and -GlcN groups after the operation.

SIGNIFICANCE

GlcN has a potential to exert a chondroprotective action on OA by inhibiting type II collagen degradation and enhancing type II collagen synthesis in the articular cartilage.

Periodic knee injections of BMP-7 delay cartilage degeneration induced by excessive running in rats

Strenuous running of rats enhances mechanical stress on the knee, thereby inducing degeneration of articular cartilage. Bone morphogenetic protein-7 (BMP-7) has an inhibitory effect on cartilage degeneration, suggesting its usefulness for human osteoarthritis patients. However, its mode of administration should be investigated. We examined whether weekly knee injections of BMP-7 delayed the progression of cartilage degeneration. Wistar rats were forced to run 30 km in 6 weeks on a rodent treadmill, and BMP-7 was injected weekly into the knee. Macroscopically and histologically, this strenuous running regimen induced cartilage degeneration. Weekly injections of 250 ng BMP-7 delayed the progression of cartilage degeneration. Immunohistochemically, in the control knee, type II collagen expression decreased, while BMP-7 expression in chondrocytes slightly increased. Interestingly, weekly injection of BMP-7 increased BMP-7 expression even 9 days after the final injection. Disulfate disaccharide keratan sulfate in serum transiently increased in the control group, while it remained at a low level in the BMP-7 group. Weekly BMP-7 injection increased BMP-7 expression in chondrocytes and its effect seemed to last more than 7 days. The effect of BMP-7 could be monitored by serum keratan sulfate concentration. Periodical injections of BMP-7 delayed progression of cartilage degeneration induced by excessive running in rats.

The 'sweet' and 'bitter' involvement of glycosaminoglycans in lung diseases: pharmacotherapeutic relevance

The extracellular matrix (ECM) plays a significant role in the structure and function of the lung. The ECM is a three-dimensional fibre mesh, comprised of various interconnected and intercalated macromolecules, among which are the glycosaminoglycans (GAG). GAG are long, linear and highly charged, heterogeneous polysaccharides that are composed of a variable number of repeating disaccharide units (macromolecular sugars) and most of them, as their name implies, have a sweet taste. In the lung, GAG support the structure of the interstitium, the subepithelial tissue and the bronchial walls, and are secreted in the airway secretions. Besides maintaining lung tissue structure, GAG also play an important role in lung function as they regulate hydration and water homeostasis, modulate the inflammatory response and influence lung tissue repair and remodelling. However, depending on their size and/or degree of sulphation, and their immobilization or solubilization in the ECM, specific GAG in the lung either live up to their sweet taste/name, supporting normal lung physiology, or they are associated to 'bitter' effects, related to lung pathology. The present review discusses the biological role of GAG in the lung as well as the involvement of these molecules in various respiratory diseases. Given the great structural diversity of GAG, understanding the changes in GAG expression that occur in lung diseases may lead to novel targets for pharmacological intervention in order to prevent and/or to treat a range of lung diseases.

Differential effects of exogenous and endogenous hyaluronan on contraction and strength of collagen gels

The addition of exogenous hyaluronan to biomaterial scaffolds has been an important area of investigation for many decades. The ability to manipulate endogenous production of hyaluronan via the hyaluronan syntheses has offered another mechanism to study the effect of hyaluronan. While the literature suggests that exogenously added hyaluronan and endogenously produced hyaluronan will have varying impacts on extracellular matrix organization and function, no studies have directly shown this phenomenon. In this investigation, we demonstrate that the addition of exogenous high molecular weight (approximately 1 MDa) hyaluronan and hyaluronan oligosaccharides have a distinct impact on both contraction and strength of smooth muscle cell-seeded collagen gels when compared to the effects of hyaluronan that is endogenously produced by the hyaluronan synthases. More specifically, the addition of exogenous high molecular weight hyaluronan resulted in more compact collagen gels with a higher ultimate tensile strength, whereas the endogenous overproduction of hyaluronan resulted in the opposite effect. We suggest that the addition of exogenous HA to collagen gels represents a model for the therapeutic administration of HA, whereas the addition of excess HA to a tissue via the endogenous overexpression of has represents a model for the pathological accumulation of HA.