M. Kloppenburg

Urinary CTX-II levels are associated with radiographic subtypes of osteoarthritis in hip, knee, hand, and facet joints in subject with familial osteoarthritis at multiple sites: the GARP study

Objective: To assess the relation between the urinary concentrations of type II collagen C-telopeptide (UCTX-II) and radiographic signs of osteoarthritis (ROA) in the GARP (Genetics, Arthrosis and Progression) study. Methods: UCTX-II levels were measured in GARP study participants, who are sibling pairs predominantly with symptomatic osteoarthritis at multiple sites. Kellgren and Lawrence scores were used to assess ROA in the knees, hips, hands, and vertebral facet joints, and spinal disc degeneration. A proportionate score was made for each joint location, based on the number of joints with ROA. The sum total ROA score represents a measure of cartilage abnormalities within each patient. By using linear mixed models the total ROA score and the joint site specific ROA scores were correlated with the UCTX-II level. Results: In 302 subjects the mean (SD) and median (range) for UCTX-II were 265 (168) and 219 (1346) ng/mmol creatine, respectively. There was a significant association between the total ROA score and UCTX-II levels. Subsequent multivariate analysis showed that the joint site specific ROA score at all joint sites, except for spinal disc degeneration, contributed independently to this association. Conclusions: The total ROA score of GARP patients, representing cartilage abnormalities at the most prevalent ROA joint locations, showed an excellent correlation with UCTX-II levels. The specific ROA scores at the hip, hand, facet, and knee joints additively and independently explained this association. Even in patients with osteoarthritis at multiple sites, UCTX-II may be a sensitive quantitative marker of ROA.

High prevalence of vertebral fractures despite normal bone mineral density in patients with long-term controlled acromegaly.

OBJECTIVEnTo establish the prevalence of osteoporosis, vertebral fractures (VFs), and non-VFs in acromegaly patients with long-term controlled disease and factors potentially influencing fracture risk.nnnDESIGNnCase-control study. Patients and measurements Eighty-nine patients (46% male, mean age: 58 years) were included. We studied VFs and non-VFs, bone mineral density (BMD), and markers of bone turnover. In 48 patients, BMD assessment was also obtained 7 years prior to the current study. To compare VF prevalence, data from a sample of the Dutch population (n=3469) were used.nnnRESULTSnVF prevalence was 59% (men 64% and women 54%), significantly increased when compared with controls (odds ratio up to 6.5), and independent of the duration of disease control, BMD, markers of bone turnover, and acromegalic disease characteristics. Mean number of VFs per patient was 3.4±0.3 (range 1-8). There was no relationship between the number and severity of fractures, parameters of bone turnover, and follow-up BMD measurements. BMD did not change during prolongation of follow-up by 7 years of controlled acromegaly.nnnCONCLUSIONnThere is a very high prevalence of VFs in acromegaly patients with long-term controlled disease, independently of BMD. In view of the significant morbidity and mortality associated with VFs in general and the inability of BMD to predict fracture risk in acromegalic patients, we propose to include VF assessment, for example by lateral conventional radiographs of the spine in the screening of patients with acromegaly, both at diagnosis and during follow-up after establishment of disease control.

Infrapatellar fat pad of patients with end-stage osteoarthritis inhibits catabolic mediators in cartilage

Objective Adipose tissue is known to release inflammatory cytokines and growth factors. In this exploratory study, the authors examined whether the infrapatellar fat pad (IPFP) closely located to cartilage in the knee joint can affect cartilage metabolism. In addition, the authors analysed whether the macrophage types present in IPFP could explain the effect on cartilage. Methods IPFP explants obtained during total knee replacement of 29 patients with osteoarthritis (OA) were used to make fat-conditioned medium (FCM). Explants of bovine cartilage were cultured with or without FCM. Nitric oxide (NO) and glycosaminoglycan release and gene expression of matrix-degrading enzymes in cartilage were analysed. To stimulate catabolic processes in the cartilage, the authors added interleukin 1β, and the effect of six FCMs was evaluated. The presence of different types of macrophages (CD68+, CD86+ and CD206+) in OA IPFPs was compared with subcutaneous adipose tissue samples and IPFP samples from patients with an anterior cruciate ligament rupture. Results FCM alone reduced NO and glycosaminoglycan release and matrix metalloproteinase (MMP)1 gene expression by the cartilage. Moreover, when catabolic conditions were enhanced with interleukin 1β, FCM inhibited NO production as well as MMP1 and MMP3 gene expression and increased collagen type II gene expression. Significantly more CD206+ cells were present in OA IPFP samples than in subcutaneous fat or anterior cruciate ligament IPFP samples. Conclusion In contrast to the authors expectations, medium conditioned by end-stage OA IPFP inhibited catabolic processes in cartilage. CD206+ cells present in the IPFPs used for making the FCM might have contributed to the inhibition of catabolic processes in the cartilage.

Association of matrilin-3 polymorphisms with spinal disc degeneration and osteoarthritis of the first carpometacarpal joint of the hand

Background: Seven polymorphisms in the matrilin-3(MATN3) gene were previously tested for genetic association with hand osteoarthritis in an Icelandic cohort. One of the variants, involving a conserved amino acid substitution (T303M; SNP5), was related to idiopathic hand osteoarthritis. Objectives: To investigate SNP5 and two other promising polymorphisms (rs2242190; SNP3, rs8176070; SNP6) for association with radiographic and symptomatic hand osteoarthritis phenotypes, as well as other heritable phenotypes. Methods: Polymorphisms were examined in two distinct cohorts of subjects: a population based sample from the Rotterdam study (nu200a=u200a809), and affected siblings from the genetics, osteoarthrosis and progression (GARP) study (nu200a=u200a382). Results: The originally described association of T303M with the hand osteoarthritis phenotype was not observed in the populations studied. In the Rotterdam sample, however, carrying the T allele of T303M conferred an odds ratio of 2.9 (95% confidence interval (CI), 1.2 to 7.3; pu200a=u200a0.02) for spinal disc degeneration. In the GARP study, carriers of the A allele of SNP6 had an odds ratio of 2.0 (95% CI, 1.3 to 3.1, pu200a=u200a0.004) for osteoarthritis of the first carpometacarpal joint (CMC1) as compared with the Rotterdam sample as a control group. Subsequent haplotype analysis showed that a common haplotype, containing the risk allele of SNP6, conferred a significant risk in sibling pairs with CMC1 osteoarthritis (odds ratiou200a=u200a1.7 (95% CI, 1.1 to 2.7, pu200a=u200a0.02)). Conclusions: These associations suggest that the MATN3 region also determines susceptibility to spinal disc degeneration and CMC1 osteoarthritis.

Cytokine production by infrapatellar fat pad can be stimulated by interleukin 1β and inhibited by peroxisome proliferator activated receptor α agonist

Background Infrapatellar fat pad (IPFP) might be involved in osteoarthritis (OA) by production of cytokines. It was hypothesised that production of cytokines is sensitive to environmental conditions. Objectives To evaluate cytokine production by IPFP in response to interleukin (IL)1β and investigate the ability to modulate this response with an agonist for peroxisome proliferator activated receptor α (PPARα), which is also activated by lipid-lowering drugs such as fibrates. Methods Cytokine secretion of IPFP was analysed in the medium of explant cultures of 29 osteoarthritic patients. IPFP (five donors) and synovium (six donors) were cultured with IL-1β and PPARα agonist Wy14643. Gene expression of IL-1β, monocyte chemoattractant protein (MCP1), (IL-6, tumour necrosis factor (TNF)α, leptin, vascular endothelial growth factor (VEGF), IL-10, prostaglandin-endoperoxide synthase (PTGS)2 and release of TNFα, MCP1 and prostaglandin E2 were compared with unstimulated IPFP and synovium explants. Results IPFP released large amounts of inflammatory cytokines, adipokines and growth factors. IL-1β increased gene expression of PTGS2, TNFα, IL-1β, IL-6 and VEGF and increased TNFα release in IPFP. MCP1, leptin, IL-10 gene expression and MCP1, leptin and PGE2 release did not increase significantly. Synovium responded to IL-1β similarly to IPFP, except for VEGF gene expression. Wy14643 decreased gene expression of PTGS2, IL-1β, TNFα, MCP1, VEGF and leptin in IPFP explants and IL-1β, TNFα, IL-6, IL-10 and VEGF in synovium that responded to IL-1β. Conclusion IPFP is an active tissue within the joint. IPFP cytokine production is increased by IL-1β and decreased by a PPARα agonist. The effects were similar to effects seen in synovium. Fibrates may represent a potential disease-modifying drug for OA by modulating inflammatory properties of IPFP and synovium.

Innate production of tumour necrosis factor α and interleukin 10 is associated with radiological progression of knee osteoarthritis

Objectives: Inflammation may contribute to progression of knee osteoarthritis (OA). Therefore, we investigated whether innate differences in the inflammatory response regarding cytokine production were associated with radiological progression of knee OA. Methods: Symptomatic patients with knee OA (nu200a=u200a89) were included. Standardised posteroanterior knee radiographs were obtained at baseline and after 24 months. Medial and lateral tibiofemoral joint space narrowing (JSN) was graded with the Altman atlas. Radiological progression was defined as an increase of at least one score in JSN total scores. Whole blood samples were stimulated with lipopolysaccharide (LPS) (10 ng/ml). Relative risks (RR) with 95% CIs of OA progression in relation to quartiles of innate ex vivo production of interleukin (IL)1β, tumour necrosis factor (TNF)α, IL1 receptor antagonist (Ra) and IL10 were calculated. Results: Progression of JSN was present in 29 (33.7%) of 86 followed patients after 2 years. Patients in the highest quartile of TNFα production had a sixfold increased risk of JSN progression (age, sex and body mass index adjusted RR 6.1, 95% CI 1.4 to 9.8) and patients in the highest quartile of IL10 production had a fourfold increased risk of JSN progression (age, sex and body mass index adjusted RR 4.3, 95% CI 1.7 to 6.2), both in comparison with those patients in the lowest quartile. No significant associations were found between variations in IL1β and IL1Ra production and JSN progression. Conclusion: The innate capacity to produce TNFα and IL10 upon LPS stimulation is associated with radiological progression of knee OA, even over a relatively short follow-up period of 2 years.

Allelic variation at the C-reactive protein gene associates to both hand osteoarthritis severity and serum high sensitive C-reactive protein levels in the GARP study

Objective: To gain more insight into the role of genetic variation of the C-reactive protein (CRP) gene in serum CRP levels and osteoarthritis (OA). Methods: Serum high sensitive CRP (S-HsCRP) levels were measured in the Genetics of osteoARthritis and Progression (GARP) study. Furthermore, to assess genetic variation of the CRP gene, genotypes of five tagging single nucleotide polymorphisms were assessed in the GARP study and a random control sample. Results: A significant and consistent relation between S-HsCRP levels and observed haplotypes was identified. Additionally, a CRP haplotype, which also associated to a significantly higher expected phenotypic mean S-HsCRP level, was associated to severe hand OA. This haplotype was tagged by a single nucleotide polymorphism (rs3091244). Carriers of this allele have an increased risk for the presence of severe hand OA with an OR of 2.3 (95% confidence interval 1.2 to 4.3, pu200a=u200a0.009). Conclusions: A haplotype of the CRP gene, associated to high basal S-HsCRP level, is also associated to severity of hand OA, indicating that innate high basal S-HsCRP levels may influence OA onset.

Inflammatory Cells in Patients with Endstage Knee Osteoarthritis: A Comparison between the Synovium and the Infrapatellar Fat Pad

Objective. To get a better understanding of inflammatory pathways active in the osteoarthritic (OA) joint, we characterized and compared inflammatory cells in the synovium and the infrapatellar fat pad (IFP) of patients with knee OA. Methods. Infiltrating immune cells were characterized by flow cytometry in 76 patients with knee OA (mean age 63.3, 52% women, median body mass index 28.9) from whom synovial tissue (n = 40) and IFP (n = 68) samples were obtained. Pain was assessed by the visual analog scale (VAS; 0–100 mm). Spearman rank correlations and linear regression analyses adjusted for sex and age were performed. Results. Macrophages and T cells, followed by mast cells, were the most predominant immune cells in the synovium and IFP, and were equally abundant in these tissues. Macrophages and T cells secreted mostly proinflammatory cytokines even without additional stimulation, indicating their activated state. Accordingly, most CD4+ T cells had a memory phenotype and contained a significant population of cells expressing activation markers (CD25+, CD69+). Interestingly, the percent of CD69+ T cells was higher in synovial than IFP CD4+ T cells. Preliminary analyses indicated that the number of synovial CD4+ T cells were associated with VAS pain (β 0.51, 95% CI 0.09–1.02, p = 0.02). Conclusion. Our data suggest that the immune cell composition of the synovium and the IFP is similar, and includes activated cells that could contribute to inflammation through secretion of proinflammatory cytokines. Moreover, preliminary analyses indicate that synovial CD4+ T cells might associate with pain in patients with endstage OA of the knee.

Progression of acromegalic arthropathy despite long-term biochemical control: a prospective, radiological study

OBJECTIVEnArthropathy is an invalidating complication of acromegaly, of which the prognosis and determinants are currently unknown in treated acromegaly. Therefore, the objective of the present study was to investigate the radiographic progression of arthropathy over a mean follow-up period of 2.6 years and determinants of outcome in patients with long-term, well-controlled acromegaly.nnnDESIGNnProspective follow-up study.nnnMETHODSnIn a prospective cohort study we studied 58 patients (mean age 62, women 41%) with controlled acromegaly for a mean of 17.6 years. Radiographic progression of joint disease was defined by the Osteoarthritis Research Society International classification as a 1-point increase in joint space narrowing (JSN) or osteophyte scores on radiographs of the hands, knees, and hips obtained at the first study visit and after 2.6 years. Potential risk factors for progression were assessed.nnnRESULTSnProgression of osteophytes and JSN was observed in 72 and 74% of patients respectively. Higher age predisposed for osteophyte progression. Patients with biochemical control by somatostatin (SMS) analogs had more progression of osteophytosis than surgically cured patients (odds ratio=18.9, P=0.025), independent of age, sex, BMI, baseline IGF1 SDS and exon 3 deletion of the GHR. This was also evident for JSN progression, as were higher age and higher baseline IGF1 SDS.nnnCONCLUSIONSnAcromegalic patients have progressive JSN and osteophytosis, despite long-term biochemical control. Parameters reflecting GH/IGF1 activity were associated with progressive joint disease. Remarkably, biochemical control by SMS analogs was associated with more progression than surgical cure. Although the present study is not a randomized controlled trial, this may indicate insufficient GH control according to current criteria and the need for more aggressive therapy.

A gain of function mutation in TNFRSF11B encoding osteoprotegerin causes osteoarthritis with chondrocalcinosis

Objective To identify pathogenic mutations that reveal underlying biological mechanisms driving osteoarthritis (OA). Methods Exome sequencing was applied to two distant family members with dominantly inherited early onset primary OA at multiple joint sites with chondrocalcinosis (familial generalised osteoarthritis, FOA). Confirmation of mutations occurred by genotyping and linkage analyses across the extended family. The functional effect of the mutation was investigated by means of a cell-based assay. To explore generalisability, mRNA expression analysis of the relevant genes in the discovered pathway was explored in preserved and osteoarthritic articular cartilage of independent patients undergoing joint replacement surgery. Results We identified a heterozygous, probably damaging, read-through mutation (c.1205A=>T; p.Stop402Leu) in TNFRSF11B encoding osteoprotegerin that is likely causal to the OA phenotype in the extended family. In a bone resorption assay, the mutant form of osteoprotegerin showed enhanced capacity to inhibit osteoclastogenesis and bone resorption. Expression analyses in preserved and affected articular cartilage of independent OA patients showed that upregulation of TNFRSF11B is a general phenomenon in the pathophysiological process. Conclusions Albeit that the role of the molecular pathway of osteoprotegerin has been studied in OA, we are the first to demonstrate that enhanced osteoprotegerin function could be a directly underlying cause. We advocate that agents counteracting the function of osteoprotegerin could comply with new therapeutic interventions of OA.