Serum hyaluronic acid concentration predicts the progression of joint space narrowing in normal knees and established knee osteoarthritis - a five-year prospective cohort study

S-Equol Ameliorates Menopausal Osteoarthritis in Rats through Reducing Oxidative Stress and Cartilage Degradation

Osteoarthritis (OA) is a chronic degenerative disease leading to articular cartilage destruction. Menopausal and postmenopausal women are susceptible to both OA and osteoporosis. S-equol, a soy isoflavone-derived molecule, is known to reduce osteoporosis in estrogen-deficient mice, but its role in OA remains unknown. This study aimed to explore the effect of S-equol on different degrees of menopausal OA in female Sprague-Dawley (SD) rats induced by estrogen deficiency caused by bilateral ovariectomy (OVX) combined with intra-articular injection of mono-iodoacetate (MIA). Knee joint histopathological change; serum biomarkers of bone turnover, including N-terminal propeptide of type I procollagen (PINP), C-terminal telopeptide of type I collagen (CTX-I) and N-terminal telopeptide of type I collagen (NTX-I); the cartilage degradation biomarkers hyaluronic acid (HA) and N-terminal propeptide of type II procollagen (PIINP); and the matrix-degrading enzymes matrix metalloproteinases (MMP)-1, MMP-3 and MMP-13, as well as the oxidative stress-inducing molecules nitric oxide (NO) and hydrogen peroxide (H2O2), were assessed for evaluation of OA progression after S-equol supplementation for 8 weeks. The results showed that OVX without or with MIA injection induced various severity levels of menopausal OA by increasing pathological damage, oxidative stress, and cartilage matrix degradation to various degrees. Moreover, S-equol supplementation could significantly reduce these increased biomarkers in different severity levels of OA. This indicates that S-equol can lessen menopausal OA progression by reducing oxidative stress and the matrix-degrading enzymes involved in cartilage degradation.

A Comprehensive, Multidisciplinary Assessment for Knee Osteoarthritis Following Traumatic Unilateral Lower Limb Loss in Service Members

INTRODUCTION

Knee osteoarthritis (KOA) is a primary source of long-term disability and decreased quality of life (QoL) in service members (SM) with lower limb loss (LL); however, it remains difficult to preemptively identify and mitigate the progression of KOA and KOA-related symptoms. The objective of this study was to explore a comprehensive cross-sectional evaluation, at the baseline of a prospective study, for characterizing KOA in SM with traumatic LL.

MATERIALS AND METHODS

Thirty-eight male SM with traumatic unilateral LL (23 transtibial and 15 transfemoral), 9.5 ± 5.9 years post-injury, were cross-sectionally evaluated at initial enrollment into a prospective, longitudinal study utilizing a comprehensive evaluation to characterize knee joint health, functionality, and QoL in SM with LL. Presences of medial, lateral, and/or patellofemoral articular degeneration within the contralateral knee were identified via magnetic resonance imaging(for medically eligible SM; Kellgren-Lawrence Grade [n = 32]; and Outerbridge classification [OC; n = 22]). Tri-planar trunk and pelvic motions, knee kinetics, along with temporospatial parameters, were quantified via full-body gait evaluation and inverse dynamics. Concentrations of 26 protein biomarkers of osteochondral tissue degradation and inflammatory activity were identified via serum immunoassays. Physical function, knee symptoms, and QoL were collected via several patient reported outcome measures.

RESULTS

KOA was identified in 12 of 32 (37.5%; KL ≥ 1) SM with LL; however, 16 of 22 SM presented with patellofemoral degeneration (72.7%; OC ≥ 1). Service members with versus without KOA had a 26% reduction in the narrowest medial tibiofemoral joint space. Biomechanically, SM with versus without KOA walked with a 24% wider stride width and with a negative correlation between peak knee adduction moments and minimal medial tibiofemoral joint space. Physiologically, SM with versus without KOA exhibited elevated concentrations of pro-inflammatory biomarker interleukin-7 (+180%), collagen breakdown markers collagen II cleavage (+44%), and lower concentrations of hyaluronic acid (-73%) and bone resorption biomarker N-telopeptide of Type 1 Collagen (-49%). Lastly, there was a negative correlation between patient-reported contralateral knee pain severity and patient-reported functionality and QoL.

CONCLUSIONS

While 37.5% of SM with LL had KOA at the tibiofemoral joint (KL ≥ 1), 72.7% of SM had the presence of patellofemoral degeneration (OC ≥ 1). These findings demonstrate that the patellofemoral joint may be more susceptible to degeneration than the medial tibiofemoral compartment following traumatic LL.

Early Castration in Horses Does Not Impact Osteoarticular Metabolism

The castration of stallions is traditionally performed after puberty, at around the age of 2 years old. No studies have focused on the effects of early castration on osteoarticular metabolism. Thus, we aimed to compare early castration (3 days after birth) with traditional castration (18 months of age) in horses. Testosterone and estradiol levels were monitored from birth to 33 months in both groups. We quantified the levels of biomarkers of cartilage and bone anabolism (CPII and N-MID) and catabolism (CTX-I and CTX-II), as well as of osteoarthritis (HA and COMP) and inflammation (IL-6 and PGE2). We observed a lack of parallelism between testosterone and estradiol synthesis after birth and during puberty in both groups. The extra-gonadal synthesis of steroids was observed around the 28-month mark, regardless of the castration age. We found the expression of estrogen receptor (ESR1) in cartilage and bone, whereas androgen receptor (AR) expression appeared to be restricted to bone. Nevertheless, with respect to osteoarticular metabolism, steroid hormone deprivation resulting from early castration had no discernable impact on the levels of biomarkers related to bone and cartilage metabolism, nor on those associated with OA and inflammation. Consequently, our research demonstrated that early castration does not disrupt bone and cartilage homeostasis.

Hyaluronic Acid in Rheumatology

Hyaluronic acid (HA), also known as hyaluronan, is an anionic glycosaminoglycan widely distributed throughout various tissues of the human body. It stands out from other glycosaminoglycans as it lacks sulfation and can attain considerable size: the average human synovial HA molecule weighs about 7 million Dalton (Da), equivalent to roughly 20,000 disaccharide monomers; although some sources report a lower range of 3-4 million Da. In recent years, HA has garnered significant attention in the field of rheumatology due to its involvement in joint lubrication, cartilage maintenance, and modulation of inflammatory and/or immune responses. This review aims to provide a comprehensive overview of HA's involvement in rheumatology, covering its physiology, pharmacology, therapeutic applications, and potential future directions for enhancing patient outcomes. Nevertheless, the use of HA therapy in rheumatology remains controversial with conflicting evidence regarding its efficacy and safety. In conclusion, HA represents a promising therapeutic option to improve joint function and alleviate inflammation and pain.

Ultrasound-Guided Injections of HYADD4 for Knee Osteoarthritis Improves Pain and Functional Outcomes at 3, 6, and 12 Months without Changes in Measured Synovial Fluid, Serum Collagen Biomarkers, or Most Synovial Fluid Biomarker Proteins at 3 Months

BACKGROUND

Prior studies have demonstrated improved efficacy when intra-articular (IA) therapeutics are injected using ultrasound (US) guidance. The aim of this study was to determine if clinical improvement in pain and function after IA hyaluronic acid injections using US is associated with changes in SF volumes and biomarker proteins at 3 months.

METHODS

49 subjects with symptomatic knee OA, BMI < 40, and KL radiographic grade II or III participated. Subjects with adequate aspirated synovial fluid (SF) volumes received two US-guided IA-HA injections of HYADD4 (24 mg/3 mL) 7 days apart. Clinical evaluations at 3, 6, and 12 months included WOMAC, VAS, PCS scores, 6 MWD, and US-measured SF depth. SF and blood were collected at 3 months and analyzed for four serum OA biomarkers and fifteen SF proteins.

RESULTS

Statistical differences were observed at 3, 6, and 12 months compared to baseline values, with improvements at 12 months for WOMAC scores (50%), VAS (54%), and PCS scores (24%). MMP10 levels were lower at 3 months without changes in SF volumes, serum levels of C2C, COMP, HA, CPII, or SF levels of IL-1 ra, IL-4, 6, 7, 8, 15, 18, ILGFBP-1, 3, and MMP 1, 2, 3, 8, 9. Baseline clinical features or SF biomarker protein levels did not predict responsiveness at 3 months.

CONCLUSIONS

Clinical improvements were observed at 12 months using US needle guidance for IA HA, whereas only one SF protein biomarker protein was different at 3 months. Larger studies are needed to identify which SF biomarkers will predict which individual OA patients will receive the greatest benefit from IA therapeutics.

Cartilage regeneration and inflammation modulation in knee osteoarthritis following injection of allogeneic adipose-derived mesenchymal stromal cells: a phase II, triple-blinded, placebo controlled, randomized trial

BACKGROUND

Intra-articular injection of mesenchymal stromal cells (MSCs) with immunomodulatory features and their paracrine secretion of regenerative factors proposed a noninvasive therapeutic modality for cartilage regeneration in knee osteoarthritis (KOA).

METHODS

Total number of 40 patients with KOA enrolled in two groups. Twenty patients received intra-articular injection of 100 × 10⁶ allogeneic adipose-derived mesenchymal stromal cells (AD-MSCs), and 20 patients as control group received placebo (normal saline). Questionnaire-based measurements, certain serum biomarkers, and some cell surface markers were evaluated for 1 year. Magnetic resonance imaging (MRI) before and 1 year after injection was performed to measure possible changes in the articular cartilage.

RESULTS

Forty patients allocated including 4 men (10%) and 36 women (90%) with average age of 56.1 ± 7.2 years in control group and 52.8 ± 7.5 years in AD-MSCs group. Four patients (two patients from AD-MSCs group and two patients from the control group) excluded during the study. Clinical outcome measures showed improvement in AD-MSCs group. Hyaluronic acid and cartilage oligomeric matrix protein levels in blood serum decreased significantly in patients who received AD-MSCs (P < 0.05). Although IL-10 level significantly increased after 1 week (P < 0.05), the serum level of inflammatory markers dramatically decreased after 3 months (P < 0.001). Expressions of CD3, CD4, and CD8 have a decreasing trend during 6-month follow-up (P < 0.05), (P < 0.001), and (P < 0.001), respectively. However, the number of CD25⁺ cells increased remarkably in the treatment group 3 months after intervention (P < 0.005). MRI findings showed a slight increase in the thickness of tibial and femoral articular cartilages in AD-MSCs group. The changes were significant in the medial posterior and medial anterior areas of ​​the tibia with P < 0.01 and P < 0.05, respectively.

CONCLUSION

Inter-articular injection of AD-MSCs in patients with KOA is safe. Laboratory data, MRI findings, and clinical examination of patients at different time points showed notable articular cartilage regeneration and significant improvement in the treatment group.

TRIAL REGISTRATION

Iranian registry of clinical trials (IRCT, https://en.irct.ir/trial/46 ), IRCT20080728001031N23. Registered 24 April 2018.

Comparison of clinical outcome, cartilage turnover, and inflammatory activity following either intra-articular or a combination of intra-articular with intra-osseous platelet-rich plasma injections in osteoarthritis knee: A randomized, clinical trial

BACKGROUND

The objective of the study was to determine the changes in clinical outcome (pain and knee activity) and assess bone/ cartilage biomarkers and inflammatory activity in persons with osteoarthritis (OA) knee following a single injection of intra-articular platelet-rich plasma (IA-PRP) and combination of intra-articular, intraosseous PRP (IA+IO-PRP).

METHODS

This prospective, randomized, single-blind clinical trial was conducted at a tertiary care teaching hospital in India. Ninety-six persons with OA knee with a Kellgren-Lawrence score of 3 were randomized into three groups- Group-I (IA-PRP), Group-II (IA+IO-PRP)], Group-III, [intra-articular normal saline (IA-NS)]. The primary outcome was a visual analog scale (VAS) for pain. The secondary outcomes were the Knee Injury and Osteoarthritis Outcome Score (KOOS), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), bone/ cartilage turnover biomarkers [C-telopeptide (CTX-II), N-telopeptide (NTX-I), cartilage oligomeric matrix protein (COMP), N-terminal propeptide of collagen type-IIA (PIIANP), and hyaluronic acid (HA)], ultrasonography (USG) findings of the knee joint. The outcome measures were assessed at baseline, 6, and 12 weeks of follow-up.

RESULTS

Compared to IA-NS injection, IA-PRP and IA+IO-PRP injections significantly improved VAS-pain and KOOS scores at 6 and 12 weeks. Furthermore, both PRP groups showed a significant reduction in ESR, CRP, and CTX-II at 12 weeks following PRP injections. In addition, at 12 weeks, the IA+IO-PRP group showed a significant reduction (p=0.009) in NTX-I level. Persons in the IA+IO-PRP group reported significant reductions in the synovial-effusion and infra-patellar bursitis.

CONCLUSIONS

Significant clinical improvements were noticed following IA-PRP and IA-IO-PRP injections compared to IA-NS injections. Both PRP groups reported a significant reduction in ESR, CRP, and CTX-II levels at 12 weeks. Persons in the IA+IO-PRP group reported significant changes in u-NTX-I level and knee-USG findings.

Sex-specific effects of calving season on joint health and biomarkers in Montana ranchers

BACKGROUND

Agricultural workers have a higher incidence of osteoarthritis (OA), but the etiology behind this phenomenon is unclear. Calving season, which occurs in mid- to late-winter for ranchers, includes physical conditions that may elevate OA risk. Our primary aim was to determine whether OA biomarkers are elevated at the peak of calving season compared to pre-season, and to compare these data with joint health survey information from the subjects. Our secondary aim was to detect biomarker differences between male and female ranchers.

METHODS

During collection periods before and during calving season, male (n = 28) and female (n = 10) ranchers completed joint health surveys and provided samples of blood, urine, and saliva for biomarker analysis. Statistical analyses examined associations between mean biomarker levels and survey predictors. Ensemble cluster analysis identified groups having unique biomarker profiles.

RESULTS

The number of calvings performed by each rancher positively correlated with plasma IL-6, serum hyaluronic acid (HA) and urinary CTX-I. Thiobarbituric acid reactive substances (TBARS), a marker of oxidative stress, was significantly higher during calving season than pre-season and was also correlated with ranchers having more months per year of joint pain. We found evidence of sexual dimorphism in the biomarkers among the ranchers, with leptin being elevated and matrix metalloproteinase-3 diminished in female ranchers. The opposite was detected in males. WOMAC score was positively associated with multiple biomarkers: IL-6, IL-2, HA, leptin, C2C, asymmetric dimethylarginine, and CTX-I. These biomarkers represent enzymatic degradation, inflammation, products of joint destruction, and OA severity.

CONCLUSIONS

The positive association between number of calvings performed by each rancher (workload) and both inflammatory and joint tissue catabolism biomarkers establishes that calving season is a risk factor for OA in Montana ranchers. Consistent with the literature, we found important sex differences in OA biomarkers, with female ranchers showing elevated leptin, whereas males showed elevated MMP-3.

Effusion detected by ultrasonography and overweight may predict the risk of knee osteoarthritis in females with early knee osteoarthritis: a retrospective analysis of Iwaki cohort data

BACKGROUND

Knee osteoarthritis (OA) has enormous medical and socioeconomic burdens, which early diagnosis and intervention can reduce. We investigated the influence of knee effusion on the progression of knee OA in patients with early knee OA.

METHODS

A total of 404 participants without radiographic knee OA were assessed from a 3-year longitudinal analysis. Participants were classified into non-OA and early knee OA groups. The effusion area (mm²) was quantified using ultrasonography. Receiver operating characteristic and logistic regression analyses were performed.

RESULTS

At the 3-year follow-up, 114 of 349 knees (32%) had progressed from non-OA and 32 of 55 knees (58%) had progressed from early knee OA to radiographic knee OA. Logistic regression analysis showed that female sex (odds ratio [OR] 3.36, 95% confidence interval [CIs] 2.98-5.42), early knee OA (OR 2.02, 95% CI 1.08-3.75), body mass index (OR 1.11, 95% CI 1.02-1.19), and effusion area (OR 1.01, 95% CI 1.01-1.02) were significantly correlated with knee OA progression. Women who were overweight (body mass index ≥ 25 kg/m²) with more severe effusion had a higher risk of OA progression (area under the curve = 0.691, OR = 6.00) compared to those not overweight (area under the curve = 0.568, OR = 1.91).

CONCLUSION

Knee effusion may be an indicator of the progression of early-stage knee OA.

A comprehensive review of intraarticular knee injection therapy, geniculate injections, and peripheral nerve stimulation for knee pain in clinical practice

The knee is the most common joint in adults associated with morbidity. Many pathologies are associated with knee damage, such as gout or rheumathoid arthritis, but the primary condition is osteoarthritis (OA). Not only can osteoarthritis cause significant pain, but it also can result in signficant disability as well. Treatment for this condition varies, starting off with oral analgesics and physical therapy to surgical total knee replacmenet. In the gamut of this various treatments, a conservative approach has included intra articular steroid injections. With time, researchers and clinicians determined that other components injected to the knee may additionally provide relief of this condition. In this investigation, we describe different types of knee injections such as platelet-rich plasma (PRP), hyaluronic acid, stem cells, and prolotherapy. Additionally, we describe the role of geniculate knee injections, radiofrequency, and periopheral nerve stimulation. These treatments should be considered for patients with knee pain refractory to conservative therapies.

Methods for isolating and analyzing physiological hyaluronan: a review

The carbohydrate hyaluronan (or hyaluronic acid, HA) is found in all human tissues and biofluids where it has wide-ranging functions in health and disease that are dictated by both its abundance and size. Consequently, hyaluronan evaluation in physiological samples has significant translational potential. Although the analytical tools and techniques for probing other biomolecules such as proteins and nucleic acids have become standard approaches in biochemistry, those available for investigating hyaluronan are less well established. In this review, we survey methods related to the assessment of native hyaluronan in biological specimens, including protocols for separating it from biological matrices and technologies for determining its concentration and molecular weight.

Associations between serum biomarkers of cartilage metabolism and serum hyaluronic acid, with risk factors, pain categories, and disease severity in knee osteoarthritis: a pilot study

BACKGROUND

Specific serum biomarkers of cartilage metabolism such as cartilage oligomeric matrix protein (sCOMP) and procollagen type II C-terminal propeptide (sPIICP) as well as hyaluronan (sHA), a biomarker of synovitis, have been implicated in the pathophysiology of knee osteoarthritis (OA). However, the associations of these biomarkers with the severity of the disease and OA risk factors, including age and obesity remain inconclusive. This analysis examines the associations between these serum biomarkers and the radiographic severity of OA and knee pain, as wells as obesity, the age and gender of the participants, and other OA risk factors.

METHODS

From 44 patients with early knee OA and 130 patients with late knee OA we analyzed the radiographic severity of the disease using the Kellgren and Lawrence (KL) grading system. Moreover, 38 overweight healthy individuals were used as a control group. Specific information was collected from all participants during their recruitment. The levels of the three serum biomarkers were quantified using commercially available ELISA kits. Serum biomarkers were analyzed for associations with the average KL scores and pain in both knees, as well as with specific OA risk factors.

RESULTS

The levels of sCOMP were elevated in patients with severe late OA and knee pain and correlated weakly with OA severity. A weakly correlation of sHA levels and OA severity OA was observed. We demonstrated that only sPIICP levels were markedly decreased in patients with late knee OA suggesting the alterations of cartilage metabolism in this arthritic disease. Moreover, we found that sPIICP has the strongest correlation with obesity and the severity of OA, as well as with the knee pain at rest and during walking regardless of the severity of the disease. ROC analysis showed that the area under the ROC curve (AUC) was 0.980 (95% CI: 0.945-0.995; p < 0.0001), suggesting high diagnostic accuracy of sPIICP. Interestingly, gender and age had also an effect on the levels of sPIICP.

CONCLUSION

This study revealed the potential of serum PIICP to be used as a biomarker to monitor the progression of knee OA, however, further studies are warranted to elucidate its clinical implication.

Bone marrow lesion severity was associated with proximal tibial inclination in early knee osteoarthritis

PURPOSE

This study aimed to investigate the effect of tibial plateau (TP) inclination and serum bone metabolic markers on bone marrow lesion (BML) in the general Japanese population with early knee osteoarthritis (EKOA).

METHODS

A total of 441 female volunteers who participated in the Iwaki Health Promotion Project in 2017 were enrolled. Participants without radiographic abnormalities were divided into normal and EKOA groups according to the Luyten's classification criteria for EKOA. The medial proximal tibial angle (MPTA), growth plate-TP angle, and growth plate-medial tibial plateau (MTP) angle were measured on standing anteroposterior radiographs of the knees. BML severity on T2-weighted fat-suppressed magnetic resonance imaging (MRI) was scored using the Whole-Organ MRI Score method. Serum levels of N-telopeptide of type I collagen, tartrate-resistant acid phosphatase-5b (TRACP-5b), bone-specific alkaline phosphatase, procollagen type I N-terminal propeptide, pentosidine, and homocysteine were assessed. Linear regression analysis was conducted to investigate the relationship between proximal tibial inclination, BML, and serum bone metabolic markers.

RESULTS

The growth plate was observed in 309 (70%) participants, and 48 (16%) participants had EKOA. The mean MPTA, growth plate-TP angle, and growth plate-MTP angle were 86.1 ± 5.9°, 3.6 ± 1.1°, and 9.9 ± 2.6°, respectively. The MPTA was negatively correlated with the growth plate-TP and growth plate-MTP angles (p = 0.006, p < 0.001). Participants with EKOA who had BML exhibited greater growth plate-MTP angle than those who did not (p = 0.018). Regression analysis revealed that BML severity was positively associated with MPTA (p = 0.036) and a bone formation marker (p = 0.045).

CONCLUSION

BML severity was positively associated with proximal tibial inclination and serum TRACP-5b level in participants with EKOA and normal knees, respectively. Assessment of proximal tibial inclination may provide insight into potential BML risk. Residual medial tibial inclination may potentially result in knee pain and symptoms in EKOA.

LEVEL OF EVIDENCE

III.

Clinically Relevant Molecular Biomarkers for Use in Human Knee Osteoarthritis: A Systematic Review

OBJECTIVE

Biomarkers in osteoarthritis (OA) could serve as objective clinical indicators for various disease parameters, and act as surrogate endpoints in clinical trials for disease-modifying drugs. The aim of this systematic review was to produce a comprehensive list of candidate molecular biomarkers for knee OA after the 2013 ESCEO review and discern whether any have been studied in sufficient detail for use in clinical settings.

DESIGN

MEDLINE and Embase databases were searched between August 2013 and May 2018 using the keywords "knee osteoarthritis," "osteoarthritis," and "biomarker." Studies were screened by title, abstract, and full text. Human studies on knee OA that were published in the English language were included. Excluded were studies on genetic/imaging/cellular markers, studies on participants with secondary OA, and publications that were review/abstract-only. Study quality and bias were assessed. Statistically significant data regarding the relationship between a biomarker and a disease parameter were extracted.

RESULTS

A total of 80 studies were included in the final review and 89 statistically significant individual molecular biomarkers were identified. C-telopeptide of type II collagen (CTXII) was shown to predict progression of knee OA in urine and serum in multiple studies. Synovial fluid vascular endothelial growth factor concentration was reported by 2 studies to be predictive of knee OA progression.

CONCLUSION

Despite the clear need for biomarkers of OA, the lack of coordination in current research has led to incompatible results. As such, there is yet to be a suitable biomarker to be used in a clinical setting.

Relationship between abnormalities detected by magnetic resonance imaging and knee symptoms in early knee osteoarthritis

We investigated the prevalence of magnetic resonance imaging (MRI) findings and their relationship with knee symptoms in women without radiographic evidence of knee osteoarthritis (KOA). This cross-sectional cohort study included 359 Japanese women without radiographic evidence of KOA (Kellgren‒Lawrence grade < 2). All participants underwent T2-weighted fat-suppressed MRI of their knees. Structural abnormalities (cartilage damage, bone marrow lesions [BMLs], subchondral cysts, bone attrition, osteophytes, meniscal lesions, and synovitis) were scored according to the whole-organ MRI score method. Knee symptoms were evaluated using the Knee Injury and Osteoarthritis Outcome Score. Participants were divided into early and non-KOA groups based on early KOA classification criteria. Logistic regression analysis was performed to evaluate the relationship between MRI abnormalities and knee symptoms. Cartilage damage was the most common abnormality (43.5%). The prevalences of cartilage damage, BMLs, subchondral cysts, bone attrition, meniscal lesions, and synovitis were higher in patients with early KOA than in those without. Synovitis (odds ratio [OR] 2.254, P = 0.002) and meniscal lesions (OR 1.479, P = 0.031) were positively associated with the presence of early KOA. Synovitis was most strongly associated with knee pain and might be a therapeutic target in patients with early KOA.

Prevalence and associated factors of radiographic vertebral fractures in men: Rural population cross-sectional observation study in Japan

BACKGROUND

Osteoporotic fractures constitute a major health concern in both women and men, particularly with the aging population. Many potential risk factors of vertebral fractures (VFx) have been identified in women, but not in men. Several reports have focused on the quality of life (QOL) of clinically diagnosed VFx, but not much has been reported on quantified QOL scores of incidental radiographic VFx in men. This cross-sectional study aimed to investigate the associated factors and the influence of incident radiographic VFx on QOL of men.

METHODS

A total of 401 volunteer men aged 40 years or older (40-92 years) participated in this study. The mean age was 60.5 ± 11.8 years. Prevalent VFx were identified on the lateral lumbar spinal radiographs using the semiquantitative method. Bone mineral density, body composition, smoking, alcohol intake, past medical history, Mini-Mental State Examination, grip strength, gait speed, and biochemical markers were examined. QOL was evaluated using the 36-Item Short-Form Health Survey and the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire.

RESULTS

Of the 401 subjects, 35 men (8.7%) had the prevalence of VFx. After adjustment for age, the presence of VFx was significantly associated with IGF-1 (odds ratio 0.985; p = 0.02). QOL scores were not significantly associated with VFx after adjustment for age.

CONCLUSIONS

IGF-1 is the mediator of growth hormone, and IGF-1 stimulates the proliferation, differentiation, and mineralization of osteoblastic cells. The prevalence of VFx in men was 8.7%, and IGF-1 was significantly lower in the VFx group than in the non-VFx group.

Proteoglycan-4 and hyaluronan composition in synovial fluid and serum from clinical equine subjects: relationship to cartilage boundary lubrication and viscosity of synovial fluid

Purpose: In experimental models of equine joint-injury and osteoarthritis synovial fluid (SF) composition (proteoglycan-4, hyaluronan) can vary, along with changes to SF mechanical function (lubrication, viscosity). The study hypotheses were a) clinical equine joint-injury and disease results in altered SF composition and diminished mechanical function, and b) serum composition (proteoglycan-4 or hyaluronan) changes concurrently. The objectives were to characterize composition (proteoglycan-4, hyaluronan), and function of SF and serum from normal horses compared to clinical groups: osteoarthritis, acute-joint-injury, and osteochondrosis.Materials and Methods: Equine samples of SF (from various joints) and blood were collected at the point-of-care. Proteoglycan-4 concentrations were measured by amplified-luminescence-proximity-assay and enzyme-linked-immunosorbent-assay in SF and serum, respectively. Molecular-weight of hyaluronan was characterized by agarose-gel-electrophoresis, and concentrations were measured by enzyme-linked-immunosorbent-assay kit. Biomechanical function of SF was characterized by an in vitro cartilage-on-cartilage friction test, and viscosity test.Results: SF proteoglycan-4 concentration increased in acute-joint-injury (1185 ± 276 versus normal 205 ± 106 µg/mL, µ± SEM, p < 0.01), with increased percentage of lower molecular-weight hyaluronan in acute-joint-injury and osteochondrosis. SF and serum proteoglycan-4 concentrations were correlated in normal horses (r² = 0.85, p < 0.05), but not in clinical groups. Cartilage-lubricating ability was unchanged, although steady-shear viscosity of acute-joint-injury SF decreased from normal.Conclusion: Composition of SF from cases of equine acute-joint-injury changed; both proteoglycan-4 concentration and hyaluronan molecular-weight were altered, with decreased SF viscosity, but no associated changes to serum. Serum proteoglycan-4 and hyaluronan concentrations alone may not be useful biomarkers for equine joint-injury or disease.

Reduced serum levels of anti-Mullerian hormone is a putative biomarker of early knee osteoarthritis in middle-aged females at menopausal transition

A recent epidemiological study revealed that the highest prevalence of early knee osteoarthritis (OA) was observed in females aged ≥ 50 years. The major causal factor of early knee OA was sex. Despite the relevance of estrogen in evaluating chondral and bone metabolism in OA, it is not easily clinically monitored because irregular menstrual cycles induce unstable female hormone patterns during menopausal transitions. Anti-Mullerian hormone (AMH) has been found to be a new stable biomarker to predict menopause. This study aimed to investigate the association between menopausal transition and early knee OA by using serum biomarkers, with special focus on AMH. A total of 518 female volunteers who participated in the Iwaki cohort study were enrolled and divided into pre-menopause and post-menopause groups. Weight-bearing anterior–posterior knee radiographs were classified by Kellgren–Lawrence (KL) grade, and grade ≥ 2 was defined as radiographic knee OA. In participants with KL grades 0 and 1, early knee OA was defined by Luyten’s criteria. AMH, luteinizing hormone, follicle-stimulating hormone, estradiol (pg/ml), prolactin, and testosterone were measured on the female hormones. Bone mineral density at a distal radius was measured. The predictive power of female hormones for early knee OA was estimated by ROC analysis (comparison of area under curve, AUC) and regression analysis. Fifty-two participants (10.0%) were diagnosed with early knee OA and 204 (39.4%) with radiographic knee OA. In 393 (75.9%) females, menopause began. From the ROC analysis in pre-menopausal females, cutoff value of AMH for detecting early knee OA was 0.08 ng/ml (area under curve (AUC), 0.712; 95% CI, 0.527–0.897; p value, 0.025; odds ratio, 8.28). AUCs of other female hormones did not reach the level of AMH (range, 0.513 of prolactine to 0.636 of estradiol). Logistic regression analysis focusing on AMH reduction at menopausal transition showed that the related AMH below 0.08 ng/ml was significantly related to the presence of early knee OA (p = 0.035; odds ratio, 5.55). Reduced serum levels of AMH in middle-aged females were correlated with the presence of early knee OA, which might be a useful serum biomarker.

Global, regional prevalence, incidence and risk factors of knee osteoarthritis in population-based studies

BACKGROUND

Knee osteoarthritis (OA) is a major cause of disability in the elderly, however, there are few studies to estimate the global prevalence, incidence, and risk factors of knee OA.

METHODS

For this study, we searched PUBMED, EMBASE and SCOPUS from inception to April 4, 2020, without language restriction. We identified eligible studies with information on the prevalence or incidence of knee OA in population-based observational studies and extracted data from published reports. We did random-effects meta-analysis to generate estimates. This study was registered with PROSPERO (CRD42020181035).

FINDINGS

Out of 9570 records identified, 88 studies with 10,081,952 participants were eligible for this study. The pooled global prevalence of knee OA was 16⋅0% (95% CI, 14⋅3%-17⋅8%) in individuals aged 15 and over and was 22⋅9% (95% CI, 19⋅8%-26⋅1%) in individuals aged 40 and over. Correspondingly, there are around 654⋅1 (95% CI, 565⋅6-745⋅6) million individuals (40 years and older) with knee OA in 2020 worldwide. The pooled global incidence of knee OA was 203 per 10,000 person-years (95% CI, 106-331) in individuals aged 20 and over. Correspondingly, there are around annual 86⋅7 (95% CI, 45⋅3-141⋅3) million individuals (20 years and older) with incident knee OA in 2020 worldwide. The prevalence and incidence varied substantially between individual countries and increased with age. The ratios of prevalence and incidence in females and males were 1⋅69 (95% CI, 1⋅59-1⋅80, p<0⋅00) and 1⋅39 (95% CI, 1⋅24-1⋅56, p<0⋅00), respectively.

INTERPRETATION

Our study provides the global prevalence (16⋅0% [95% CI, 14⋅3%-17⋅8%]) and incidence (203 per 10,000 person-years [95% CI, 106-331]) of knee OA. These findings can be used to better assess the global health burden of knee OA. Further prospective cohort studies are warranted to identify modifiable risk factors for providing effectively preventive strategies in the early stages of the disease.

FUNDING

This work was supported by grants from the National Natural Science Foundation of China (nos. 81772384 and 81572174).

Detection of synovitis in early knee osteoarthritis by MRI and serum biomarkers in Japanese general population

To investigate synovitis' influence on early knee osteoarthritis (EKOA) by serum biomarkers and magnetic resonance imaging (MRI) findings in Japanese women. We enrolled 255 women aged 30-70 without radiographic abnormalities (Kellgren-Lawrence grade ≥ 2). Knee injury, OA outcome scores (KOOS), clinical examinations, and standing radiograph were used for classification criteria of EKOA. Participants were classified into normal knee group and EKOA group. All participants underwent MRIs of their right knee. The amount of effusion-synovitis volume was quantified. We compared serum matrix metalloproteinases-3 levels (MMP-3), high-sensitivity C-reactive protein, interleukin-6, and adiponectin between the groups. The relationship between synovitis and EOKA was investigated using multiple linear regression. Fifty-four participants (21%) were classified as EKOA. Serum MMP-3 concentration and effusion-synovitis volume were higher in patients with EKOA (p = 0.025 and p = 0.001, respectively). Effusion-synovitis volume negatively correlated with all KOOS subscales and positively correlated with serum MMP-3 concentration. Serum MMP-3 concentration was associated with effusion-synovitis volume β = 0.60, p < 0.001). There was mildly active but definitive synovitis in EKOA. This was an observational study so that no conclusions can be drawn regarding cause-effect for synovitis and symptoms. Future studies should conduct follow-up of participants with synovitis to assess the progression of knee OA.

Knee effusion evaluated by ultrasonography warns knee osteoarthritis patients to develop their muscle atrophy: a three-year cohort study

This study aimed to elucidate the relationship between the quantitative value of suprapatellar effusion and the longitudinal changes in lower-extremity muscle mass (MM) in a cohort with knee osteoarthritis (KOA). Fifty-three subjects (106 legs) with bilateral radiographic KOA at baseline (BL) were enrolled. MM was calculated by bioimpedance analysis three times at BL, and at the one-year (1Y) and three-year (3Y) follow-ups. The longitudinal change in the lower-extremity MM was calculated by subtracting MM_BL from MM_1Y, and MM_1Y from MM_3Y. Subjects with ≥1.0 z-score loss were defined as having severe MM loss (SMML). Effusion was evaluated as the sagittal area of suprapatellar pouch (mm²) by ultrasonography. The ROC curve was drawn to determine the cut-off of effusion area. General estimating equations (GEEs) were conducted with the prevalence of SMML as the dependent variable and with the cut-off of effusion area as the independent variable. Sixteen legs (15.1%) demonstrated SMML_BL-1Y and another sixteen legs demonstrated SMML_1Y-3Y. GEEs revealed that individuals with ≥90 mm² effusion had significantly higher odds of SMML_BL-1Y prevalence (Odds ratio: 21.561; P-value: 0.003). Individuals with leachate knee effusion at BL had a significant risk of losing MM through the first year of the initial knee effusion assessment.

Early knee osteoarthritis prevalence is highest among middle-aged adult females with obesity based on new set of diagnostic criteria from a large sample cohort study in the Japanese general population

PURPOSE

A few new criteria for early detection and prevention of early knee osteoarthritis (EKOA) have been proposed. However, its prevalence, risk factors, relationship with function and prognosis have not been clarified. The purpose of this study was to investigate the prevalence of EKOA and its risk factors in the Japanese general population.

METHODS

A total of 1104 volunteers (443 males, 661 females) who participated in the Iwaki cohort study in Japan were enrolled in this cross-sectional study. Their bilateral weight-bearing anterior-posterior knee radiographs were classified by Kellgren-Lawrence (KL) grade. EKOA (KL grade 0/1) was defined according to the following criteria: knee injury and osteoarthritis outcome score < 85%, joint line tenderness, and crepitus and its prevalence among age-sex groups was calculated. Logistic regression analyses were performed to determine the risk factors for EKOA.

RESULTS

Eight hundred and twenty-two participants had KL grade 0/1, and the EKOA prevalence was 9.5% in males and 15.0% in females (p = 0.011). The prevalence of EKOA increased with age. The highest prevalence was noted in females aged 50-59 years. Logistic regression analysis showed that the risk factors for EKOA were age (p < 0.001, odds ratio (OR) 1.1), female sex (p = 0.002, OR 2.5), high body mass index (p < 0.001, OR 1.2), and history of knee injury (p < 0.001, OR 21.7).

CONCLUSIONS

The highest EKOA prevalence was observed in middle adult females (50-59 years old). The risk factors for EKOA were female sex, ageing, obesity and knee injury history, which were extremely similar to those of definitive knee osteoarthritis.

LEVEL OF EVIDENCE

Level I in diagnostic studies-investigating a diagnostic test.

Serum Cartilage Oligomeric Matrix Protein in Late-Stage Osteoarthritis: Association with Clinical Features, Renal Function, and Cardiovascular Biomarkers

This study aimed to assess associations between serum cartilage oligomeric matrix protein (sCOMP) and phenotypic characteristics in late-stage hip and knee Osteoarthritis (OA) as well as its correlation with further serum markers of possible comorbidities in the Ulm Osteoarthritis Study. Moreover, the prognostic relevance of preoperative sCOMP concentrations for short-term functionality and pain outcomes after hip or knee joint replacement was explored. Preoperative serum samples and detailed information about the health status (i.e., WOMAC scores, Hannover Functionality Status (FFbH)) of 754 OA patients undergoing total joint replacement were included. Spearman rank-correlation coefficients and multiple linear regression models were used to evaluate the relationships between sCOMP, other serum markers, and health outcomes. There was a significant positive association between sCOMP and markers of renal (cystatin C, creatinine, and eGFR) and cardiac (e.g., NT-proBNP) impairment. Since renal failure might cause accumulation of sCOMP, additional adjustment with eGFR was performed. Preoperative sCOMP levels in knee OA but not hip OA patients were positively associated with FFbH, WOMAC function sub-scale and total WOMAC scale as well as the post-operative WOMAC stiffness sub-scale six months after surgery. Our data clearly demonstrate an association between sCOMP and renal function as well as other confounding factors, which should be considered in future biomarker studies.

The Effects of Annatto Tocotrienol Supplementation on Cartilage and Subchondral Bone in an Animal Model of Osteoarthritis Induced by Monosodium Iodoacetate

Osteoarthritis is a degenerative joint disease which primarily affects the articular cartilage and subchondral bones. Since there is an underlying localized inflammatory component in the pathogenesis of osteoarthritis, compounds like tocotrienol with anti-inflammatory properties may be able to retard its progression. This study aimed to determine the effects of oral tocotrienol supplementation on the articular cartilage and subchondral bone in a rat model of osteoarthritis induced by monosodium iodoacetate (MIA). Thirty male Sprague-Dawley rats (three-month-old) were randomized into five groups. Four groups were induced with osteoarthritis (single injection of MIA at week 0) and another served as the sham group. Three of the four groups with osteoarthritis were supplemented with annatto tocotrienol at 50, 100 and 150 mg/kg/day orally for five weeks. At week 5, all rats were sacrificed, and their tibial-femoral joints were harvested for analysis. The results indicated that the groups which received annatto tocotrienol at 100 and 150 mg/kg/day had lower histological scores and cartilage remodeling markers. Annatto tocotrienol at 150 mg/kg/day significantly lowered the osteocalcin levels and osteoclast surface of subchondral bone. In conclusion, annatto tocotrienol may potentially retard the progression of osteoarthritis. Future studies to confirm its mechanism of joint protection should be performed.

Symptomatic bone marrow lesions induced by reduced bone mineral density in middle-aged women: a cross-sectional Japanese population study

BACKGROUND

The etiology of bone marrow lesions (BMLs) without knee osteoarthritis (KOA) and their association with bone fragility are unclear. We aimed to investigate the association between BMLs, bone mineral density (BMD), and bone markers in women without radiographic evidence of KOA.

METHODS

This single-center cross-sectional study in a Japanese population included 266 women without radiographic evidence of KOA, which was defined as a Kellgren-Lawrence grade < 2. All participants underwent coronal and sagittal T2-weighted fat-suppressed magnetic resonance imaging of their right knee. BML severity was scored according to the Whole-Organ MRI Scoring method. BMD was measured by dual-energy X-ray absorptiometry of the forearm. Levels of bone markers (bone-alkaline phosphatase [BAP], type I procollagen N-terminal propeptide [PINP], cross-linked N-telopeptide of type I collagen [NTx], and tartrate-resistant acid phosphatase-5b [TRACP-5b]), pentosidine, and homocysteine were assessed in the serum. Knee symptoms were evaluated on the basis of the Knee injury and Osteoarthritis and Outcome Score (KOOS). Participants were divided into symptomatic knee and asymptomatic knee groups on the basis of their KOOS according to the classification criteria for early KOA. Multiple linear regression analysis was performed to evaluate the relationship between BMLs, BMD, and bone markers.

RESULTS

The prevalence of BML was 35.3%. Age and some bone marker levels (BAP, PINP, NTx, and TRACP-5b) were higher, and all KOOS subscale scores and BMD were lower in participants with BMLs than in those without BMLs. On multiple linear regression analysis, BMD was negatively associated with BMLs (p = 0.014) in participants with symptomatic knees. There was no such association in participants with asymptomatic knees (p = 0.918). Among the bone markers, BAP (p = 0.006) and PINP (p = 0.043) were positively associated with BMLs in participants with symptomatic knees, while BAP (p = 0.038) and TRACP-5b (p = 0.011) were positively associated with BMLs in participants with asymptomatic knees.

CONCLUSIONS

In symptomatic Japanese women without radiographic evidence of KOA, BMD is negatively associated and some bone markers are positively associated with BMLs after adjustment for age and BMI. Thus, maintaining systemic bone metabolism could contribute to BML prevention in patients with pre-radiographic KOA.

Bone Marrow Mesenchymal Stromal Cell Treatment in Patients with Osteoarthritis Results in Overall Improvement in Pain and Symptoms and Reduces Synovial Inflammation

Patients with late‐stage Kellgren‐Lawrence knee osteoarthritis received a single intra‐articular injection of 1, 10, or 50 million bone marrow mesenchymal stromal cells (BM‐MSCs) in a phase I/IIa trial to assess safety and efficacy using a broad toolset of analytical methods. Besides safety, outcomes included patient‐reported outcome measures (PROMs): Knee Injury and Osteoarthritis Outcome Score (KOOS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC); contrast‐enhanced magnetic resonance imaging (MRI) for cartilage morphology (Whole Organ MRI Scores [WORMS]), collagen content (T2 scores), and synovitis; and inflammation and cartilage turnover biomarkers, all over 12 months. BM‐MSCs were characterized by a panel of anti‐inflammatory markers to predict clinical efficacy. There were no serious adverse events, although four patients had minor, transient adverse events. There were significant overall improvements in KOOS pain, symptoms, quality of life, and WOMAC stiffness relative to baseline; the 50 million dose achieved clinically relevant improvements across most PROMs. WORMS and T2 scores did not change relative to baseline. However, cartilage catabolic biomarkers and MRI synovitis were significantly lower at higher doses. Pro‐inflammatory monocytes/macrophages and interleukin 12 levels decreased in the synovial fluid after MSC injection. The panel of BM‐MSC anti‐inflammatory markers was strongly predictive of PROMs over 12 months. Autologous BM‐MSCs are safe and result in significant improvements in PROMs at 12 months. Our analytical tools provide important insights into BM‐MSC dosing and BM‐MSC reduction of synovial inflammation and cartilage degradation and provide a highly predictive donor selection criterion that will be critical in translating MSC therapy for osteoarthritis. stem cells translational medicine2019;8:746&757

A study of the factors associated with cervical spinal disc degeneration, with a focus on bone metabolism and amino acids, in the Japanese population: a cross sectional study

Background

The physical and biochemical factors responsible for cervical disc degeneration, and resulting in various spinal disorders, remain unclear. This study aimed to evaluate the correlation between cervical spinal canal stenosis and degeneration of intervertebral discs, and to analyze the factors related to disc degeneration in the Japanese population.

Methods

Three hundred and forty-four Japanese general residents underwent investigations, including magnetic resonance imaging of the cervical spine, in our health check project. We measured anteroposterior diameters at the levels of the cervical spinal disc in mid sagittal plane magnetic resonance imaging and evaluated disc degeneration. Spearman correlation coefficient was used to evaluate whether the diameters were correlated with disc degenerative scores. Stepwise multiple linear regression analysis was conducted with the score of disc degeneration as the dependent variable; and age, physical measurement values, bone mineral density of the forearm, and the value of serum bone metabolic markers and amino acids as the independent variables for each sex.

Results

As the age increased, the anteroposterior diameters decreased in both sexes. The minimum anteroposterior diameters were correlated with the disc degenerative scores (Spearman r = − 0.59, p < 0.001 in men, Spearman r = − 0.53, p < 0.001 in women). In multiple linear regression analysis, age, cross-linked N-telopeptide of type 1 collagen and isoleucine were significantly correlated with the cervical disc degenerative score in men (R² = 0.47), and age and lysine were significantly correlated with the degenerative score in women (R² = 0.50).

Conclusion

The factors responsible for cervical disc degeneration differed between men and women. Whether modifying these significant factors is possible, or whether this intervention would contribute to prevention of disc degeneration requires future studies.

NLRP3 as a potentially novel biomarker for the management of osteoarthritis

Osteoarthritis (OA) was previously thought of as 'wear and tear' as humans age, however there is increasing evidence to support an inflammatory theory. The nucleotide-binding and oligomerization domain-like receptor containing protein 3 (NLRP3) inflammasome has been implicated in the pathogenesis of a number of arthritic disorders, producing proinflammatory cytokines and degradative enzymes such as Interleukin-1 beta (IL-1β), Tumour necrosis factor alpha (TNF-α) and Matrix metalloproteinase-3 (MMP-3) which drive cartilage degeneration and synovial inflammation. This review aims to summarise the evidence of NLRP3 involvement in OA. Currently, treatment options focus on management of the disease and to date there is no cure. The development of novel biomarkers for OA could improve diagnosis, treatment and management. Importantly, this review provides detail on the involvement of the NLRP3 inflammasome in OA pathology and how its members could act as potential biomarkers to assist clinical decisions.

Quantitative genetics of circulating Hyaluronic Acid (HA) and its correlation with hand osteoarthritis and obesity-related phenotypes in a community-based sample

BACKGROUND

One of the potential molecular biomarkers of osteoarthritis (OA) is hyaluronic acid (HA). HA levels may be related to the severity and progression of OA. However, little is known about the contribution of major risk factors for osteoarthritis, e.g. obesity-related phenotypes and genetics to HA variation.

AIM

To clarify the quantitative effect of these factors on HA.

SUBJECTS AND METHODS

An ethnically homogeneous sample of 911 apparently healthy European-derived individuals, assessed for radiographic hand osteoarthritis (RHOA), HA, leptin, adiponectin, and several anthropometrical measures of obesity-related phenotypes was studied. Model-based quantitative genetic analysis was used to reveal genetic and shared environmental factors affecting the variation of the study's phenotypes.

RESULTS

The HA levels significantly correlated with the age, RHOA, adiponectin, obesity-related phenotypes, and the waist-to-hip ratio. The putative genetic effects contributed significantly to the variation of HA (66.2 ± 9.3%) and they were also significant factors in the variations of all the other studied phenotypes, with the heritability estimate ranging between 0.122 ± 4.4% (WHR) and 45.7 ± 2.2% (joint space narrowing).

CONCLUSIONS

This is the first study to report heritability estimates of HA variation and its correlation with obesity-related phenotypes, ADP and RHOA. However, the nature of genetic effects on HA and its correlation with other study phenotypes require further clarification.

Osteoarthritis Year in Review 2016: biomarkers (biochemical markers)

PURPOSE

The aim of this "Year in Review" article is to summarize and discuss the implications of biochemical marker related articles published between the Osteoarthritis Research Society International (OARSI) 2015 Congress in Seattle and the OARSI 2016 Congress in Amsterdam.

METHODS

The PubMed/MEDLINE bibliographic database was searched using the combined keywords: 'biomarker' and 'osteoarthritis'. The PubMed/MEDLINE literature search was conducted using the Advanced Search Builder function (http://www.ncbi.nlm.nih.gov/pubmed/advanced).

RESULTS

Over two hundred new biomarker-related papers were published during the literature search period. Some papers identified new biomarkers whereas others explored the biological properties and clinical utility of existing markers. There were specific references to several adipocytokines including leptin and adiponectin. ADAM Metallopeptidase with Thrombospondin Type 1 motif 4 (ADAMTS-4) and aggrecan ARGS neo-epitope fragment (ARGS) in synovial fluid (SF) and plasma chemokine (CeC motif) ligand 3 (CCL3) were reported as potential new knee biomarkers. New and refined proteomic technologies and novel assays including a fluoro-microbead guiding chip (FMGC) for measuring C-telopeptide of type II collagen (CTX-II) in serum and urine and a novel magnetic nanoparticle-based technology (termed magnetic capture) for collecting and concentrating CTX-II, were described this past year.

CONCLUSION

There has been steady progress in osteoarthritis (OA) biomarker research in 2016. Several novel biomarkers were identified and new technologies have been developed for measuring existing biomarkers. However, there has been no "quantum leap" this past year and identification of novel early OA biomarkers remains challenging. During the past year, OARSI published a set of recommendations for the use of soluble biomarkers in clinical trials, which is a major step forward in the clinical use of OA biomarkers and bodes well for future OA biomarker development.

Endotoxin free hyaluronan and hyaluronan fragments do not stimulate TNF-α, interleukin-12 or upregulate co-stimulatory molecules in dendritic cells or macrophages

The extracellular matrix glycosaminoglycan, hyaluronan, has been described as a regulator of tissue inflammation, with hyaluronan fragments reported to stimulate innate immune cells. High molecular mass hyaluronan is normally present in tissues, but upon inflammation lower molecular mass fragments are generated. It is unclear if these hyaluronan fragments induce an inflammatory response or are a consequence of inflammation. In this study, mouse bone marrow derived macrophages and dendritic cells (DCs) were stimulated with various sizes of hyaluronan from different sources, fragmented hyaluronan, hyaluronidases and heavy chain modified-hyaluronan (HA-HC). Key pro-inflammatory molecules, tumour necrosis factor alpha, interleukin-1 beta, interleukin-12, CCL3, and the co-stimulatory molecules, CD40 and CD86 were measured. Only human umbilical cord hyaluronan, bovine testes and Streptomyces hyaluronlyticus hyaluronidase stimulated macrophages and DCs, however, these reagents were found to be contaminated with endotoxin, which was not fully removed by polymyxin B treatment. In contrast, pharmaceutical grade hyaluronan and hyaluronan fragments failed to stimulate in vitro-derived or ex vivo macrophages and DCs, and did not induce leukocyte recruitment after intratracheal instillation into mouse lungs. Hence, endotoxin-free pharmaceutical grade hyaluronan does not stimulate macrophages and DCs in our inflammatory models. These results emphasize the importance of ensuring hyaluronan preparations are endotoxin free.