Whole-body bone scintigraphy provides a measure of the total-body burden of osteoarthritis for the purpose of systemic biomarker validation

Multiple joint osteoarthritis (MJOA): What's in a name?

OBJECTIVE

To summarize the current state of the literature regarding multi-joint osteoarthritis (MJOA) and discuss important future directions.

DESIGN

A narrative review of the author's work and other key references on this topic with a focus on the Johnston County studies, definitions of MJOA and their impact, multi-site pain in osteoarthritis (OA), genetics and biomarkers in MJOA, and perspectives on future work.

RESULTS

MJOA is variably defined and lacks a clear consensus definition, making comprehensive study challenging. Involvement of both symptoms and structural changes of OA in multiple joints in an individual is common, but patterns vary by sex, race/ethnicity, and other factors. Outcomes (e.g., general health, function, falls, mortality) are negatively impacted by a greater whole-body OA burden. Recent genetic and biomarker studies including whole-body OA assessments have begun to shed some light on potentially unique factors in the MJOA population.

CONCLUSIONS

Consideration of MJOA is essential for ongoing study of OA phenotypes, epidemiology, risk factors, genetics, biomarkers, and outcomes, to fully understand and eventually limit the negative impact of OA burden on health.

Can bone scintigraphy reflect the progression of osteoarthritis after unicompartmental knee arthroplasty?

BACKGROUND

Bone scintigraphy (BS) has been reported to be a useful predictor of osteoarthritis (OA) progression in primary knee OA. However, no previous studies have explored the relationship between BS and OA progression in the retained compartments after unicompartmental knee arthroplasty (UKA). Thus, we evaluated whether OA progresses to other compartments in patients who undergo UKA and if increased uptake on BS is associated with OA progression in other compartments after UKA.

METHODS

A total of 41 patients with knee BS at least five years after UKA were included. Radiographic OA progression in other compartments was assessed by grading and comparing OA severity in each patient using the Kellgren-Lawrence grading system (K-L grade) and Osteoarthritis Research Society International (OARSI) atlas score. After UKA, the correlation between BS uptake and radiographic OA progression was analyzed in each retained compartment. A correlation analysis was also performed to evaluate the association between BS uptake and OA progression grades.

RESULTS

A significant progression of OA was observed in both contralateral tibiofemoral and patellofemoral compartments after UKA at 98.5 ± 26.0 months of follow-up (all p<0.001). No correlation was found between BS uptake and radiographic OA progression nor between BS uptake and radiographic OA progression grade in the contralateral and patellofemoral compartments.

CONCLUSIONS

Following UKA, OA progresses in the retained contralateral tibiofemoral and patellofemoral compartments over a minimum five-year follow-up period. Thus, BS is ineffective in assessing the progression of OA in these compartments.

Synovial Fluid Biomarkers in Knee Osteoarthritis: A Systematic Review and Quantitative Evaluation Using BIPEDs Criteria

OBJECTIVE

The aim of this systematic review was to analyze the evidence about the efficacy of the several synovial fluid (SF) biomarkers proposed for knee osteoarthritis (OA), categorizing them by both molecular characteristics and clinical use according to the BIPEDs criteria, to provide a comprehensive and structured overview of the current literature.

DESIGN

A systematic review was performed in May 2020 on PubMed, Cochrane Library, and Embase databases about SF biomarkers in patients with knee OA. The search was limited to articles in the last 20 years on human studies, involving patients with knee OA, reporting SF biomarkers. The evidence for each selected SF biomarker was quantified according to the 6 categories of BIPEDs classification.

RESULTS

A total of 159 articles were included in the qualitative data synthesis and 201 different SF biomarkers were identified. Among these, several were investigated multiple times in different articles, for a total of 373 analyses. The studies included 13,557 patients with knee OA. The most promising SF biomarkers were C4S, IL-6, IL-8, Leptin, MMP-1/3, TIMP-1, TNF-α, and VEGF. The "burden of disease" and "diagnostic" categories were the most represented with 132 and 106 different biomarkers, respectively.

CONCLUSIONS

The systematic review identified numerous SF biomarkers. However, despite the high number of studies on the plethora of identified molecules, the evidence about the efficacy of each biomarker is supported by limited and often conflicting findings. Further research efforts are needed to improve the understanding of SF biomarkers for a better management of patients with knee OA.

Effects of Exercise Training Alone and in Combination With Kinesio Taping on Pain, Functionality, and Biomarkers Related to the Cartilage Metabolism in Knee Osteoarthritis

OBJECTIVE

To investigate the effects of exercise training alone and in combination with kinesio taping on pain, functionality, and circulating cartilage oligomeric matrix protein (COMP), and matrix metalloproteinase (MMP)-1, and -3 at rest and immediately after walking exercise in knee osteoarthritis (OA).

DESIGN

A total of 22 female patients diagnosed with knee OA were randomly divided into the exercise training (ET) or exercise training plus kinesio taping (ET + KT) groups. The patients in the ET performed exercise training for 6 weeks. The patients in the ET + KT group were applied with kinesio tape in addition to the exercise training for 6 weeks. In both groups, 20 minutes of walking exercise were performed before and after the interventions. The pain and functional status of the patients were assessed using visual analogue scale (VAS) and Western Ontario McMasters Osteoarthritis Index (WOMAC) before and after the intervention at rest, respectively. Blood samples were taken at rest and immediately after the walking exercise before and after the interventions for the analysis of COMP, MMP-1, and MMP-3 levels.

RESULTS

In both groups, pain and functionality scores were significantly improved after the interventions (P < 0.05). COMP, MMP-1 and MMP-3 levels were higher immediately after walking exercise when compared with rest in both groups before and after the intervention (P < 0.05).

CONCLUSIONS

Exercise training and exercise training plus kinesio taping improved pain and physical function; however, the COMP, MMP-1, and MMP-3 levels did not change.

Initial results of the use of a novel semiquantitative parameter in three-phase bone scan to predict 99mTc-HMPAO-labeled leukocyte scintigraphy in patients with unilateral total knee replacement

OBJECTIVES

The aim of the study was to predict the results of 99mTc-hexamethylpropyleneamine oxime (HMPAO)-labeled autologous leukocytes scintigraphy assessing count ratios in the perfusion (Pr) and blood-pool (BPr) phase images in three-phase bone scan (3PBSr) between the prosthetic knee and the 'healthy' knee and a novel semiquantitative parameter (P/BP ratio) in patients with unilateral knee arthroplasty.

METHODS

Patients with unilateral knee arthroplasty and available 3PBS and 99mTc-HMPAO-labeled autologous leukocytes scintigraphic images were searched in two hospitals (A and B). In center A, the perfusion phase was not available. Regions of interest (ROI) were delineated in the perfusion (P) and blood-pool (BP) phase images, incorporating the prosthetic region and applying an isocontour (40% of the maximum pixel activity); corresponding mirror ROIs were placed on the healthy knee. The P/BP ratio was calculated as {[(Pr/BPr) × 100] - 100}. Receiver operator curves (ROCs) were generated for each semiquantitative parameter to identify the optimal cutoff for predicting the results of the autologous leukocytes scintigraphy.

RESULTS

In the whole group (79 patients), BPr demonstrated an area under the curve (AUC) of 0.722 (optimal cutoff = 1.43). In center A (52 patients), BPr demonstrated an AUC of 0.737 (cutoff = 1.43), whereas, in center B (27 patients), AUC for BPr was 0.718 (cutoff = 1.6). A better diagnostic performance was obtained selecting Pr (AUC = 0.918; cutoff = 2.34) and P/BP ratio (AUC = 0.947; cutoff = 26.5%) for the discrimination between septic and aseptic loosening.

CONCLUSIONS

The novel P/BP ratio seems to be a promising semiquantitative parameter to predict septic loosening. These findings warrant confirmation in larger patient samples.

Synergistic Roles of Macrophages and Neutrophils in Osteoarthritis Progression

OBJECTIVE

To evaluate the role of immune cells and their effector cytokines in the pathogenesis and progression of knee osteoarthritis (OA) in matched OA synovial fluid (SF) and synovial tissue samples.

METHODS

Cells from matched samples of synovial tissue and SF acquired from individuals undergoing total knee replacement for OA (n = 39) were characterized for immune cell-associated surface markers and intracellular cytokine expression using polychromatic flow cytometry. Additional individuals with radiographic knee OA (Kellgren/Lawrence severity grades ≥1) who had available etarfolatide (inflammatory cell) imaging (n = 26) or baseline and 3-year data on progression of radiographic knee OA (n = 85) were also assessed. SF cytokine concentrations in all cohorts were evaluated for associations with synovial tissue and SF cell phenotypes and severity of radiographic knee OA.

RESULTS

Macrophages (predominant in the synovial tissue, 53% of total cells) and neutrophils (predominant in the SF, 26% of total cells) were the major immune cell populations identified in the OA knee joints, exhibiting expression of or association with transforming growth factor β1 (TGFβ1) and elastase, respectively, in the SF. Expression levels of TGFβ1 and elastase were significantly associated with severity of radiographic knee OA. Baseline SF concentrations of TGFβ1 and elastase along with radiographic knee OA severity scores were predictive of knee OA progression, with areas under the receiver operating characteristic curves of 0.810 (for TGFβ1), 0.806 (for elastase), and 0.846 (for both TGFβ1 and elastase combined), with greater stability of prediction when both markers were utilized.

CONCLUSION

Our findings demonstrate the hitherto underappreciated role of neutrophils in the sterile inflammatory process and progression of OA. Two soluble mediators, SF elastase and TGFβ1, are strong predictors of knee OA progression, reflecting a synergistic role of neutrophil and macrophage populations in the pathogenesis and worsening of OA that could potentially be utilized to identify patients who may have a greater risk of more rapid disease progression.

Complement Expression and Activation in Osteoarthritis Joint Compartments

Objective

To investigate complement(C) factors(F) and their activation fragments expression in OA joint tissues.

Design

Immunohistochemistry and quantitative imaging were performed to analyze C3, C4, and CF (factor) B expression on osteochondral biopsies (43 patients) collected during arthroplasty. Isolated chondrocytes and synoviocytes, cartilage and synovial tissues obtained from surgical specimens of OA patients (15 patients) were cultured with or without IL-1β. Real time PCR for CFB, C3, and C4 was performed. Culture supernatants were analyzed for C3a, C5a, CFBa, and terminal complement complex (TCC) production.

Results

In osteochondral biopsies, C factor expression was located in bone marrow, in a few subchondral bone cells and chondrocytes. C3 was the most expressed while factor C4 was the least expressed factor. Gene expression showed that all C factors analyzed were expressed both in chondrocytes and synoviocytes. In chondrocyte cultures and cartilage explants, CFB expression was significantly higher than C3 and C4. Furthermore, CFB, but not C3 and C4 expression was significantly induced by IL-1β. As to C activation factors, C3a was the most produced and CFBa was induced by IL-1β in synovial tissue. TCC production was undetectable in isolated chondrocytes and synoviocytes cell culture supernatants, whereas it was significantly augmented in cartilage explants.

Conclusion

C factors were locally produced and activated in OA joint with the contribution of all tissues (cartilage, bone, and synovium). Our results support the involvement of innate immunity in OA and suggest an association between some C alternative pathway component and joint inflammation.

Biomarkers of Hand Osteoarthritis Are Detectable after Mechanical Exercise

BACKGROUND

Hand osteoarthritis (OA) is one of the most common joint diseases, but studies on biomarkers are rare. The aim of this explorative study was (a) to evaluate potential biomarkers of hand OA, (b) to identify an optimal time point to sample venous blood, and (c) to correlate biomarker levels with radiological and clinical scores.

METHODS

Four female cohorts were investigated. One with a more Heberden-accentuated OA and one with a more Bouchard-accentuated hand OA, and two symptom-free control groups aged 20-30 or 50-75 years. The venous blood was sampled before and at eight time points after mechanical exercise of the OA hand. X-rays of OA hands were assessed using the Kellgren and Lawrence as well as Kallman scores. Participants were evaluated clinically using the AUSCAN™ Index, visual analog scale (VAS), and Health Assessment Questionnaire (HAQ). Serum levels of seven biomarkers were measured by ELISA.

RESULTS

The concentrations of CPII, COMP, IL-15, sVCAM-1, NGAL, and PIIANP were significantly increased within 15 min after exercise. PIIANP was markedly elevated in the Heberden-accentuated OA group as compared to both control groups, but did not correlate with any radiological or clinical score. Analysis of the probabilistic index further revealed that CPII can distinguish between Bouchard's OA and premenopausal controls whereas COMP can discriminate between Bouchard's and Heberden's OA.

CONCLUSIONS

This study demonstrates that even previously undetectable biomarkers can be quantified in serum after mechanical exercise. Future larger studies are needed to determine specificity and sensitivity of these markers and their ability to diagnose even pre-radiological OA.

Changes in the osteochondral unit during osteoarthritis: structure, function and cartilage-bone crosstalk

In diarthrodial joints, the articular cartilage, calcified cartilage, and subchondral cortical and trabecular bone form a biocomposite - referred to as the osteochondral unit - that is uniquely adapted to the transfer of load. During the evolution of the osteoarthritic process the compositions, functional properties, and structures of these tissues undergo marked alterations. Although pathological processes might selectively target a single joint tissue, ultimately all of the components of the osteochondral unit will be affected because of their intimate association, and thus the biological and physical crosstalk among them is of great importance. The development of targeted therapies against the osteoarthritic processes in cartilage or bone will, therefore, require an understanding of the state of these joint tissues at the time of the intervention. Importantly, these interventions will not be successful unless they are applied at the early stages of disease before considerable structural and functional alterations occur in the osteochondral unit. This Review describes the changes that occur in bone and cartilage during the osteoarthritic process, and highlights strategies for how this knowledge could be applied to develop new therapeutic interventions for osteoarthritis.

Serum cartilage oligomeric matrix protein and development of radiographic and painful knee osteoarthritis. A community-based cohort of middle-aged women

CONTEXT AND OBJECTIVE

We evaluated the predictive value of serum cartilage oligomeric matrix protein (sCOMP) levels over 20 years on the development of radiographic (RKOA) and painful knee osteoarthritis (KOA) in a longitudinal cohort of middle-aged women.

MATERIALS AND METHODS

Five hundred and ninety-three women with no baseline KOA underwent 5-year knee radiographs over 20-years and were asked about knee pain a month before each assessment. A repeated measures logistic regression model was used where the outcomes were recorded at 5, 10, 15 and 20-years follow-up.

RESULTS

The highest quartile of sCOMP was associated with increased risk of RKOA with overall OR of 1.97 (95% CI: 1.33-2.91) over 20 years when compared with the lowest sCOMP quartile. The association with painful KOA was similar and also independent, but only when the fourth and third sCOMP quartiles were compared.

DISCUSSION AND CONCLUSION

This study demonstrates that sCOMP levels are predictive of subsequent structural changes and incidence of painful KOA, independently of age and BMI.

Xanthine oxidase injurious response in acute joint injury

BACKGROUND

While acute trauma is a major cause of osteoarthritis, its etiology is poorly understood. We sought to determine whether xanthine oxidase (XO), a major producer of reactive oxygen species, plays a role in the early events of acute joint injury.

METHODS

We analyzed synovial fluid from 23 subjects with recent severe acute knee injury. As a control we evaluated SF from 23 individuals with no or minimal knee osteoarthritis. We measured XO activity, reactive oxygen+reactive nitrogen species (ROS+RNS), protein oxidative damage (carbonyl), the type II collagen synthesis marker procollagen II c-propeptide (CPII) and the type II collagen degradation marker collagen type II telopeptide (CTx-II). We also measured the proinflammatory cytokine IL-6.

RESULTS

XO and ROS+RNS were higher (p=0.02 and p=0.001 respectively) in acute injury than control and were strongly positively associated (r=0.62, p=0.004). Carbonyl was higher in acute injury than control (p=0.0002) and was positively correlated with XO (r=0.68, p=0.0007) as well as with ROS+RNS (r=0.71, p=0.004). CPII was higher in acute injury than control (p<0.0001) and was negatively correlated with XO (r=-0.49, p=0.017). While CTxII was not significantly higher in acute injury than control, it was positively correlated with CPII (r=0.71, p=0.0002). IL-6 was higher in acute injury than control (p<0.0001).

CONCLUSIONS

These results are consistent with a potentially injurious effect of XO activity in acute joint injury characterized by excess free radical production and oxidative damage. These effects are associated with an inhibition of type II collagen production that may impede the ability of the injured joint to repair.

Alpha C-telopeptide of type I collagen is associated with subchondral bone turnover and predicts progression of joint space narrowing and osteophytes in osteoarthritis

OBJECTIVE

To evaluate joint tissue remodeling using the urinary collagen biomarkers urinary α-C-telopeptide of type I collagen (α-CTX) and urinary C-telopeptide of type II collagen (CTX-II) and to determine the association of these biomarkers with osteoarthritis (OA) severity, progression, and localized knee bone turnover.

METHODS

Participants (n = 149) with symptomatic and radiographic knee OA underwent fixed-flexion knee radiography at baseline and 3 years, and late-phase bone scintigraphy of both knees at baseline, which were scored semiquantitatively for osteophyte and joint space narrowing (JSN) severity and uptake intensity, with scores summed across knees. Urinary concentrations of α-CTX and CTX-II were determined by enzyme-linked immunosorbent assay. Immunohistochemical analysis of human OA knees was performed to localize the joint tissue origin of the biomarker epitopes.

RESULTS

Urinary α-CTX concentrations correlated strongly with the intensity of bone scintigraphic uptake and with JSN progression (risk ratio 13.2) and osteophyte progression (risk ratio 3). Urinary CTX-II concentrations were strongly associated with intensity of bone scintigraphic uptake, with JSN and osteophyte severity, and with OA progression based on osteophyte score. Urinary α-CTX localized primarily to high bone turnover areas in subchondral bone. CTX-II localized to the bone-cartilage interface, the tidemark, and damaged articular cartilage.

CONCLUSION

Baseline urinary α-CTX, which was localized to high turnover areas of subchondral bone, was associated with dynamic bone turnover of knees, as signified by scintigraphy, and progression of both osteophytes and JSN. Urinary CTX-II correlated with JSN and osteophyte severity and progression of osteophytes. To our knowledge, this represents the first report of serologic markers reflecting subchondral bone turnover. These collagen markers may be useful for noninvasive detection and quantification of active subchondral bone turnover and joint remodeling in knee OA.

3D osteoarthritic changes in TMJ condylar morphology correlates with specific systemic and local biomarkers of disease

OBJECTIVE

To assess 3D morphological variations and local and systemic biomarker profiles in subjects with a diagnosis of temporomandibular joint osteoarthritis (TMJ OA).

DESIGN

Twenty-eight patients with long-term TMJ OA (39.9 ± 16 years), 12 patients at initial diagnosis of OA (47.4 ± 16.1 years), and 12 healthy controls (41.8 ± 12.2 years) were recruited. All patients were female and had cone beam CT scans taken. TMJ arthrocentesis and venipuncture were performed on 12 OA and 12 age-matched healthy controls. Serum and synovial fluid levels of 50 biomarkers of arthritic inflammation were quantified by protein microarrays. Shape Analysis MANCOVA tested statistical correlations between biomarker levels and variations in condylar morphology.

RESULTS

Compared with healthy controls, the OA average condyle was significantly smaller in all dimensions except its anterior surface, with areas indicative of bone resorption along the articular surface, particularly in the lateral pole. Synovial fluid levels of ANG, GDF15, TIMP-1, CXCL16, MMP-3 and MMP-7 were significantly correlated with bone apposition of the condylar anterior surface. Serum levels of ENA-78, MMP-3, PAI-1, VE-Cadherin, VEGF, GM-CSF, TGFβb1, IFNγg, TNFαa, IL-1αa, and IL-6 were significantly correlated with flattening of the lateral pole. Expression levels of ANG were significantly correlated with the articular morphology in healthy controls.

CONCLUSIONS

Bone resorption at the articular surface, particularly at the lateral pole was statistically significant at initial diagnosis of TMJ OA. Synovial fluid levels of ANG, GDF15, TIMP-1, CXCL16, MMP-3 and MMP-7 were correlated with bone apposition. Serum levels of ENA-78, MMP-3, PAI-1, VE-Cadherin, VEGF, GM-CSF, TGFβ1, IFNγ, TNFα, IL-1α, and IL-6 were correlated with bone resorption.

"Generalized osteoarthritis": a systematic review

OBJECTIVES

Given the conflicting definitions of "generalized osteoarthritis" (GOA) in the literature, we performed a systematic review of GOA definitions, risk factors, and outcomes.

METHODS

We searched the MEDLINE literature with the terms osteoarthritis, generalized, polyarticular, multiple joint, and multi-joint to obtain articles related to GOA, following evidence-based guidelines. Titles and abstracts of 948 articles were reviewed, with full-text review of 108. Data were extracted based on pre-specified criteria for 74 articles plus 24 identified through bibliographic review (n = 98).

RESULTS

Twenty-four large cohorts (n ~ 30,000) were represented along with numerous clinical series (n ~ 9000), across 22 countries and 60 years (1952-2012). No less than 15 definitions of GOA were given in 30 studies with a stated GOA definition; at least 6 groups used a summed score of joints or radiographic grades. Prevalence estimates based on these GOA definitions were 1-80%, although most were 5-25%. Increased risk and progression of GOA was associated with age, female sex, and genetic/familial factors. Associations with increased body mass index or bone mineral density were not consistent. A study estimated the heritability of GOA at 42%. Collagen biomarker levels increased with the number of involved joints. Increased OA burden was associated with increased mortality and disability, poorer health, and function.

CONCLUSION

While there remains no standard definition of GOA, this term is commonly used. The impact on health may be greater when OA is in more than one joint. A descriptive term, such as multi-joint or polyarticular OA, designating OA of multiple joints or joint groups is recommended.

High prevalence of contralateral ankle abnormalities in association with knee osteoarthritis and malalignment

OBJECTIVE

To evaluate ankle joint abnormalities in a knee osteoarthritis (OA) cohort.

METHODS

Participants (n = 159) with symptomatic and radiographic OA in at least one knee underwent technetium-99m methylene diphosphonate bone scan (scored 0-3) of the ankles and forefeet. Knee radiographs were graded for OA features of joint space narrowing (JSN) and osteophyte (OST). Ankle symptoms and history of ankle injury were assessed by self-report. Knee alignment was measured from a long-limb radiograph. Ankle radiographs were obtained on those who returned for follow-up (n = 138) and were graded for ankle tibiotalar JSN and OST.

DESIGN

Ankle scintigraphic abnormalities were frequent (31% of individuals, one-third bilateral). Ankle symptoms were reported by 23% of individuals and history of ankle injury by 24%. Controlling for gender, age, body mass index (BMI), and contralateral predictor, ankle scintigraphic abnormalities were associated with: ipsilateral ankle symptoms (P = 0.005); contralateral knee JSN (P = 0.001), knee OST (P = 0.006) and knee malalignment (P = 0.08); and history of ankle injury or surgery of either ankle (P < 0.0001). At follow-up, scintigraphic abnormalities of the ankle were strongly associated with presence of tibiotalar radiographic OA (P < 0.0001).

CONCLUSIONS

Although considered rare, we observed a high prevalence of radiographic features of ankle OA in this knee OA cohort. History of overt ankle injury did not appear to account for the majority of ankle abnormalities. These results are consistent with a probable kinematic association of knee OA pathology and contralateral ankle abnormalities and suggest that interventions targeting mechanical factors may be needed to prevent ankle OA in the setting of knee OA.

An OA phenotype may obtain major benefit from bone-acting agents

BACKGROUND

Osteoarthritis (OA) joints display relevant microstructure alterations associated to an increase in remodeling at subchondral bone, which supports its crucial role in OA pathogenesis. Despite this, the treatment of knee OA patients with antiresorptive drugs has given discordant results, suggesting the existence of a particular patient subset with good response to halting high subchondral remodeling.

OBJECTIVE

To identify an OA phenotype that may obtain major benefit from therapy with bone-acting agents.

METHODS

A systematic review of the literature was performed by searching the Medline and PubMed databases from 1990 to April 2013 using the following keywords: subchondral bone, articular cartilage, and osteoarthritis in various combinations with bone agents, bone mineral density, and scintigraphy.

RESULTS

Early animal and human studies provided the rationale for the beneficial use of bone agents on OA cartilage damage. Several bone-acting agents have reduced low back pain and likely spondylosis progression. Recently, strontium ranelate has been reported to exert both structural and clinical benefits in knee OA patients with radiological progression. However, other antiresorptives have shown divergent results. Human studies suggest that these contradictory results may be due to the lack of well-defined OA phenotypes and an accurate methodology to recruit and follow up these patients.

CONCLUSIONS

A particular subset of postmenopausal patients with high remodeling and/or low subchondral bone density may benefit from the treatment with bone-acting agents hindering OA progression. This OA population could be identified with the simultaneous use of subchondral bone dual-energy X-ray absorptiometry and scintigraphy.

The scintigraphic evaluation and genetic correlation of joint involvements in pediatric patients with familial Mediterranean fever

PURPOSE

We aimed to evaluate the articular involvements in pediatric patients with familial Mediterranean fever (FMF) with joint symptoms by bone scintigraphy and to correlate the involved joints with the gene mutations.

MATERIALS AND METHODS

A total of 41 newly diagnosed patients in pediatric age group (28 girls and 13 boys; mean age 9.14 ± 2.91 years) with joint involvement symptoms were included in this study. Scintigraphic images were obtained at 5th min (blood pool or early phase) and starting at 3 h (late phase) after (after tracer injection) intravenous administration of technetium-99m (99mTc)-methylendiphosphonate (MDP). Genomic DNA was isolated from leukocytes using standard salting out procedure. The sequencing data were analyzed.

RESULTS

Of the 41 patients, arthritis was found in 21 (51.2%) patients. Of the 21 patients, there was single joint involvement in 15 (71.4%) patients and multiple joint involvement in six (28.6%) patients. The mean age of patients with joint involvement (8 ± 2.3 years) were considerably lower than the patients without joint involvement (10.35 ± 3.04 years), and this was statistically significant (p = 0.008). The most commonly involved joints were ankles and knees. Multiple joint involvements were most frequently observed in the M694V and M694I gene mutations (16.7%).

CONCLUSIONS

We use and recommend the bone scintigraphy in patients with FMF to determine the presence and distribution of arthritis, since bone scintigraphy is inexpensive, noninvasive, easy-to-use, and also is more sensitive in the diagnosis and distribution of arthritis than conventional radiological methods and clinical examination.

Serum cartilage metabolites as biomarkers of degenerative lumbar scoliosis

Several biomarkers have been used to evaluate osteoarthritis of the limb joints. Here we evaluated the use of serum cartilage metabolites as biomarkers for degenerative lumbar scoliosis (DLS). Fifty-two DLS patients with Cobb angle > 10° were compared with 19 control patients. Serum levels of hyaluronic acid (HA), keratan sulfate (KS), cartilage oligomeric matrix protein (COMP), collagen type II cleavage (C2C), and procollagen type II C-propeptide (CPII) were measured. Serum levels of KS (DLS 1.20 ± 0.44 µg/ml vs. control 0.98 ± 0.33 µg/ml), CPII (DLS 1905.1 ± 948.2 ng/ml vs. control 1223.6 ± 884.4 ng/ml), and C2C (DLS 219.1 ± 59.2 ng/ml vs. control 177.7 ± 71.7 ng/ml) were significantly higher in DLS. There were no significant differences in the levels of HA or COMP. There was a significant positive correlation between the Cobb angle and CPII in DLS. This is the first study to evaluate the cartilage biomarkers in DLS. The results suggest DLS patients have higher levels of type II collagen synthesis and degradation, indicated by elevated serum CPII and C2C, respectively. As type II collagen is a major component of collagens in the nucleus pulposus and facet joint cartilages, its enhanced turnover may be related to the development and progression of DLS.

Biological markers in osteoarthritis

Osteoarthritis (OA) is considered as a chronic disease with a long "silent" period. The diagnosis is generally based on clinical symptoms and radiographic changes. However X-ray has a poor sensitivity and a relatively large precision error that does not allow an early detection of OA or the monitoring of joint damage progression. The limitations of the tools that are currently available for OA assessment have been the impetus to identify specific biological markers that reflect quantitative and dynamic variations in joint remodeling. Research has focused on the structural components of cartilage matrix, especially type II collagen degradation markers. In spite of a significant increase of some markers in individuals with early stage of OA, the large overlap with control subjects indicates that the current biomarkers used alone have limited diagnostic potential. However, the combination of specific markers seems to improve the prediction of disease progression at the individual level. Several types of treatment have been investigated but the lack of medications with definitively demonstrated chondroprotective activity has limited the assessment of the potential role of biomarkers for monitoring patients' responses to the treatment of OA. In this review, we will use the BIPED classification that appeared in 2006 for OA markers to describe the potential usage of a given marker [5]. This article is part of a Special Issue entitled "Osteoarthritis".

The MURDOCK Study: a long-term initiative for disease reclassification through advanced biomarker discovery and integration with electronic health records

BACKGROUND

Facing critically low return per dollar invested on clinical research and clinical care, the American biomedical enterprise is in need of a significant transformation. A confluence of high-throughput "omic" technologies and increasing adoption of the electronic health record has fueled excitement for a new paradigm for biomedical research and practice. The ability to simultaneously measure thousands of molecular variables and assess their relationships with clinical data collected during the course of care could enable reclassification of disease not only by gross phenotypic observation but according to underlying molecular mechanism and influence of social determinants.In turn, this reclassification could enable development of targeted therapeutic interventions as well as disease prevention strategies at the individual and population levels.

METHODS/DESIGN

The MURDOCK Study consists of distinct project "horizons" or stages. Horizon 1 entailed the generation and analysis of molecular data for existing large,clinically well-annotated cohorts in four disease areas. Horizon 1.5 involves creating and maintaining a 50,000-person,community volunteer registry for biomarker signature validation and prospective studies, including integration of environmental and social data. Horizon 2 leverages and prospectively recruits Horizon 1.5 volunteers, and extends the study to additional disease areas of interest. Horizon 3 will expand the study through regional, national,and international partnerships.

DISCUSSION

The MURDOCK Study embodies a new model of team science investigation and represents a significant resource for translational research. The study team invites inquiries to form new collaborations to exploit the rich resources provided by these biospecimens and associated study data.

The TransEurope FootRace Project: longitudinal data acquisition in a cluster randomized mobile MRI observational cohort study on 44 endurance runners at a 64-stage 4,486 km transcontinental ultramarathon

BACKGROUND

The TransEurope FootRace 2009 (TEFR09) was one of the longest transcontinental ultramarathons with an extreme endurance physical load of running nearly 4,500 km in 64 days. The aim of this study was to assess the wide spectrum of adaptive responses in humans regarding the different tissues, organs and functional systems being exposed to such chronic physical endurance load with limited time for regeneration and resulting negative energy balance. A detailed description of the TEFR project and its implemented measuring methods in relation to the hypotheses are presented.

METHODS

The most important research tool was a 1.5 Tesla magnetic resonance imaging (MRI) scanner mounted on a mobile unit following the ultra runners from stage to stage each day. Forty-four study volunteers (67% of the participants) were cluster randomized into two groups for MRI measurements (22 subjects each) according to the project protocol with its different research modules: musculoskeletal system, brain and pain perception, cardiovascular system, body composition, and oxidative stress and inflammation. Complementary to the diverse daily mobile MR-measurements on different topics (muscle and joint MRI, T2*-mapping of cartilage, MR-spectroscopy of muscles, functional MRI of the brain, cardiac and vascular cine MRI, whole body MRI) other methods were also used: ice-water pain test, psychometric questionnaires, bioelectrical impedance analysis (BIA), skinfold thickness and limb circumference measurements, daily urine samples, periodic blood samples and electrocardiograms (ECG).

RESULTS

Thirty volunteers (68%) reached the finish line at North Cape. The mean total race speed was 8.35 km/hour. Finishers invested 552 hours in total. The completion rate for planned MRI investigations was more than 95%: 741 MR-examinations with 2,637 MRI sequences (more than 200,000 picture data), 5,720 urine samples, 244 blood samples, 205 ECG, 1,018 BIA, 539 anthropological measurements and 150 psychological questionnaires.

CONCLUSIONS

This study demonstrates the feasibility of conducting a trial based centrally on mobile MR-measurements which were performed during ten weeks while crossing an entire continent. This article is the reference for contemporary result reports on the different scientific topics of the TEFR project, which may reveal additional new knowledge on the physiological and pathological processes of the functional systems on the organ, cellular and sub-cellular level at the limits of stress and strain of the human body. Please see related articles: http://www.biomedcentral.com/1741-7015/10/76 and http://www.biomedcentral.com/1741-7015/10/77.

Association of knee and ankle osteoarthritis with physical performance

OBJECTIVE

The direct measurement of the ability to perform physical tasks yields information about factors contributing to poor function and insights into strategies for preventing disability. Our goal was to evaluate the relationship of walking speed and balance tests with specific radiographic features of knee and ankle osteoarthritis (OA).

METHODS

A timed eight foot walk and a standing balance test were performed by 138 participants of a longitudinal observational study of knee OA progression. Radiographic features of OA severity, joint space narrowing (JSN), a surrogate for cartilage loss and osteophyte (OST) formation, were assessed for the knee and ankle. The association of these performance measures with radiographic OA was evaluated using correlation analysis, adjusted for age, gender, body mass index (BMI), and number of comorbidities.

RESULTS

Knee and ankle JSN, but not OST, was negatively associated with specific performance tests: walking speed was associated with knee JSN (Spearman rho = -0.20, P = 0.02) and balance was associated with ankle (subtalar joint) JSN (Spearman rho = -0.22, P = 0.01). These relationships remained significant upon further control for knee and ankle pain.

CONCLUSIONS

Structural joint damage due to OA (JSN in contrast to OST) negatively impacted specific domains of physical performance. These results indicate that targeting specific joints for specific functional outcomes may be indicated, and suggest that prevention of cartilage damage in these joints is a sensible target for OA disease modification to prevent disability.

Application of biomarkers in the development of drugs intended for the treatment of osteoarthritis

OBJECTIVE

Osteoarthritis (OA) is a chronic and slowly progressive disease for which biomarkers may be able to provide a more rapid indication of therapeutic responses to therapy than is currently available; this could accelerate and facilitate OA drug discovery and development programs. The goal of this document is to provide a summary and guide to the application of in vitro (biochemical and other soluble) biomarkers in the development of drugs for OA and to outline and stimulate a research agenda that will further this goal.

METHODS

The Biomarkers Working Group representing experts in the field of OA biomarker research from both academia and industry developed this consensus document between 2007 and 2009 at the behest of the Osteoarthritis Research Society International Federal Drug Administration initiative (OARSI FDA initiative).

RESULTS

This document summarizes definitions and classification systems for biomarkers, the current outcome measures used in OA clinical trials, applications and potential utility of biomarkers for development of OA therapeutics, the current state of qualification of OA-related biomarkers, pathways for biomarker qualification, critical needs to advance the use of biomarkers for drug development, recommendations regarding practices and clinical trials, and a research agenda to advance the science of OA-related biomarkers.

CONCLUSIONS

Although many OA-related biomarkers are currently available they exist in various states of qualification and validation. The biomarkers that are likely to have the earliest beneficial impact on clinical trials fall into two general categories, those that will allow targeting of subjects most likely to either respond and/or progress (prognostic value) within a reasonable and manageable time frame for a clinical study (for instance within 1-2 years for an OA trial), and those that provide early feedback for preclinical decision-making and for trial organizers that a drug is having the desired biochemical effect. As in vitro biomarkers are increasingly investigated in the context of specific drug treatments, advances in the field can be expected that will lead to rapid expansion of the list of available biomarkers with increasing understanding of the molecular processes that they represent.

Genome-wide linkage analysis of quantitative biomarker traits of osteoarthritis in a large, multigenerational extended family

OBJECTIVE

The genetic contributions to the multifactorial disorder osteoarthritis (OA) have been increasingly recognized. The goal of the current study was to use OA-related biomarkers of severity and disease burden as quantitative traits to identify genetic susceptibility loci for OA.

METHODS

In a large multigenerational extended family (n = 350), we measured 5 OA-related biomarkers: hyaluronan (HA), cartilage oligomeric matrix protein (COMP), N-propeptide of type IIA collagen (PIIANP), C-propeptide of type II procollagen (CPII), and type II collagen neoepitope (C2C). Single-nucleotide polymorphism markers (n = 6,090) covering the whole genome were genotyped using the Illumina HumanLinkage-12 BeadChip. Variance components analysis, as implemented in the Sequential Oligogenic Linkage Analysis Routines, was used to estimate heritabilities of the quantitative traits and to calculate 2-point and multipoint logarithm of odds (LOD) scores using a polygenic model.

RESULTS

After adjusting for age and sex, we found that 4 of the 5 biomarkers exhibited significant heritability (PIIANP 0.57, HA 0.49, COMP 0.43, C2C 0.30; P < or = 0.01 for all). Fourteen of the 19 loci that had multipoint LOD scores of >1.5 were near to or overlapped with previously reported OA susceptibility loci. Four of these loci were identified by more than 1 biomarker. The maximum multipoint LOD scores for the heritable quantitative biomarker traits were 4.3 for PIIANP (chromosome 8p23.2), 3.2 for COMP (chromosome 8q11.1), 2.0 for HA (chromosome 6q16.3), and 2.0 for C2C (chromosome 5q31.2).

CONCLUSION

Herein, we report the first evidence of genetic susceptibility loci identified by OA-related biomarkers in an extended family. Our results demonstrate that serum concentrations of PIIANP, HA, COMP, and C2C have substantial heritable components, and using these biomarkers, several genetic loci potentially contributing to the genetic diversity of OA were identified.