Focal Bone Erosion Research Articles

Posterior fossa primary intracranial extraosseous Ewing’s sarcoma: case report

BackgroundPrimary intracranial Ewing’s sarcoma (ES) is a type of primitive neuroectodermal tumour and is a rare malignant tumour in children and adolescents. The imaging features of ES overlap with other central nervous system embryonal tumours, making it difficult to pinpoint a specific diagnosis. We aim to explore the clinical, neuroimaging and differential diagnoses of this entity.Case presentationWe describe a 6-month-old infant who presented with complaints of enlarging the head size and poor feeding. Imaging revealed a contrast-enhancing large solid-cystic mass lesion with internal calcification, focal bone erosion and haemorrhage in the posterior fossa. Histopathological examinations, immunohistochemistry, and molecular analysis confirmed ES.ConclusionsThe confirmative diagnosis of primary intracranial ES requires histological examination, immunohistochemical analysis, and genetic detection, along with radiological findings. Surgical excision followed by combined radiotherapy and chemotherapy is the treatment of choice.

SAT253 A Rare Case Of Osteolytic Hypercalcemia Of Malignancy In Acute Myeloid Leukemia

Abstract Disclosure: S. Elahi: None. S. Baim: None. Introduction: Acute myeloid leukemia (AML) and other leukemias do not commonly induce hypercalcemia of malignancy (HCM). Limited previous reports of AML-related HCM have largely attributed cases to inflammatory-cytokine-mediated osteoclast activation, with rare reports of calcitriol-mediated HCM and ectopic parathyroid hormone (PTH) production. We describe an unusual case of AML-induced HCM caused by direct leukemic bone invasion, which responded to bisphosphonate therapy. Case Presentation: A 59-year-old female presented with spontaneous bruising and severe leukocytosis concerning for AML. The diagnosis was confirmed by flow cytometry and bone marrow biopsy. Imaging did not reveal any gross destructive bone lesions, but showed soft tissue nodules in the lumbar region which biopsy revealed to be myeloid sarcoma. Prior to initiation of chemotherapy, the patient developed severe hypercalcemia that was treated with aggressive intravenous hydration and zoledronic acid. Intrathecal chemotherapy and high-dose glucocorticoid therapy were initiated thereafter with normalization of serum calcium levels. PTH levels were suppressed. Calcitriol and PTHrP were below normal and undetectable, respectively. Bone turnover markers (C-telopeptide and bone-specific alkaline phosphatase) were significantly elevated prior to administration of zoledronic acid and normalized post-therapy. Calcium levels did not rebound after several interruptions in chemotherapy. Bone marrow biopsy showed focal areas of erosion in trabecular bone consistent with diffuse microscopic osteolytic disease. The patient developed bisphosphonate-induced hypocalcemia following treatment with zoledronic acid, which normalized with treatment with oral calcium carbonate. Discussion: Hypercalcemia of malignancy is a very unusual consequence of AML. No currently-published reports of this phenomenon have described biopsy-proven diffuse microscopic bone erosion associated with AML. We attribute our patient’s severe HCM to large-scale focal bone erosion by AML, independent of and/or associated with concurrent bone resorption mediated by inflammatory cytokines. A single dose of zoledronic acid, a potent suppressor of bone remodeling, achieved long term control of calcium for our patient despite interruption of chemotherapy. Bisphosphonate therapy should be considered an early treatment of HCM in patients with AML due to several potential mechanisms that result in direct calcium release from the skeleton. Presentation: Saturday, June 17, 2023

Joint Damage and Neuropathic Pain in Rats Treated With Lysophosphatidic Acid.

Joint pain is a complex phenomenon that involves multiple endogenous mediators and pathophysiological events. In addition to nociceptive and inflammatory pain, some patients report neuropathic-like pain symptoms. Examination of arthritic joints from humans and preclinical animal models have revealed axonal damage which is likely the source of the neuropathic pain. The mediators responsible for joint peripheral neuropathy are obscure, but lysophosphatidic acid (LPA) has emerged as a leading candidate target. In the present study, male and female Wistar rats received an intra-articular injection of LPA into the right knee and allowed to recover for 28 days. Joint pain was measured by von Frey hair algesiometry, while joint pathology was determined by scoring of histological sections. Both male and female rats showed comparable degenerative changes to the LPA-treated knee including chondrocyte death, focal bone erosion, and synovitis. Mechanical withdrawal thresholds decreased by 20-30% indicative of secondary allodynia in the affected limb; however, there was no significant difference in pain sensitivity between the sexes. Treatment of LPA animals with the neuropathic pain drug amitriptyline reduced joint pain for over 2 hours with no sex differences being observed. In summary, intra-articular injection of LPA causes joint degeneration and neuropathic pain thereby mimicking some of the characteristics of neuropathic osteoarthritis.

Association of serum uric acid with clinical and radiological severity of knee osteoarthritis in non-gouty patients

BackgroundA growing body of evidence suggested that uric acid (UA) may contribute in the pathways underlying osteoarthritis (OA) pathogenesis; however, studies that investigated the relationship between UA and OA emerged inconclusive results. The purpose of the study was to explore the association of serum uric acid (sUA) levels with clinical severity, radiological severity of knee osteoarthritis (KOA) based on Kellgren-Lawrence (KL) grading system, and MRI changes in non-gouty patients.ResultsWOMAC scores: pain, stiffness, function, and total score are significantly higher in H-sUA group than L-sUA group (p = 0.004, p = 0.019, p = 0.018, p = 0.008 respectively). Joint space width (JSW) is significantly narrower in H-sUA group than L-sUA group (p = 0.013). H-sUA group had more frequent KL grade 4 (p < 0.001), osteophytes grade 4 (p < 0.001), focal bone erosion (p < 0.001), bone marrow lesions (p = 0.023), and synovitis (p = 0.011) than L-sUA group. Female KOA patients in H-sUA group had significantly higher pain, stiffness, and function and total WOMAC scores than L-sUA group (p = 0.003, p = 0.015, p = 0.008, p = 0.004), more frequently had KL grade 4 and osteophytes grade 4 (p = 0.003, p < 0.001), significantly narrower JSW (p = 0.016), more frequently show focal bone erosion (p = 0.002), bone marrow lesions (p = 0.019), and synovitis (p = 0.004) than L-sUA group. In regression analysis, female sex (p = 0.035), duration of KOA (p = 0.031), and sUA level (p = 0.025) were associated with KL severity. For female patients with KOA, KL severity is associated with duration of KOA (p = 0.045) and sUA (p = 0.009).ConclusionHigher sUA level is associated with higher clinical severity, higher radiographic KL grades, and more frequent MRI findings in patients with primary KOA patients. Our results also indicated that sUA level was significantly associated with KOA severity in female patients, but not in male patients. More studies are warranted to explore whether the two conditions exist simultaneously or there is a direct causal relationship between the two conditions.

Osteoclast-Derived Autotaxin, a Distinguishing Factor for Inflammatory Bone Loss.

The severity of rheumatoid arthritis (RA) correlates directly with bone erosions arising from osteoclast (OC) hyperactivity. Despite the fact that inflammation may be controlled in patients with RA, those in a state of sustained clinical remission or low disease activity may continue to accrue erosions, which supports the need for treatments that would be suitable for long-lasting inhibition of OC activity without altering the physiologic function of OCs in bone remodeling. Autotaxin (ATX) contributes to inflammation, but its role in bone erosion is unknown. ATX was targeted by inhibitory treatment with pharmacologic drugs and also by conditional inactivation of the ATX gene Ennp2 in murine OCs (ΔATXC tsk ). Arthritic and erosive diseases were studied in human tumor necrosis factor-transgenic (hTNF+/- ) mice and mice with K/BxN serum transfer-induced arthritis. Systemic bone loss was also analyzed in mice with lipopolysaccharide (LPS)-induced inflammation and estrogen deprivation. Joint inflammation and bone erosion were assessed by histology and micro-computed tomography. The role of ATX in RA was also examined in OC differentiation and activity assays. OCs present at sites of inflammation overexpressed ATX. Pharmacologic inhibition of ATX in hTNF+/- mice, as compared to vehicle-treated controls, significantly mitigated focal bone erosion (36% decrease; P < 0.05) and systemic bone loss (43% decrease; P < 0.05), without affecting synovial inflammation. OC-derived ATX was revealed to be instrumental in OC bone resorptive activity and was up-regulated by the inflammation elicited in the presence of TNF or LPS. Specific loss of ATX in OCs from mice subjected to ovariectomy significantly protected against the systemic bone loss and erosion that had been induced with LPS and K/BxN serum treatments (30% reversal of systemic bone loss [P < 0.01]; 55% reversal of erosion [P < 0.001]), without conferring bone-protective properties. Our results identify ATX as a novel OC factor that specifically controls inflammation-induced bone erosions and systemic bone loss. Therefore, ATX inhibition offers a novel therapeutic approach for potentially preventing bone erosion in patients with RA.

Prostaglandin E2 and IL-23 interconnects STAT3 and RoRγ pathways to initiate Th17 CD4+ T-cell development during rheumatoid arthritis.

The chronic inflammation associated with rheumatoid arthritis (RA) leads to focal and systemic bone erosion of the joints resulting in a crippling disability. Recent reports indicate an increase in the incidence of RA in the coming years, placing a significant burden on healthcare resources. The incidence of RA is observed to be increasing with age and a significant proportion of those new cases will be aggressively erosive. The altered physiology, due to immune disturbances, contributes towards RA pathogenesis. The imbalance of inflammatory cytokines and non-cytokine immune modulators such as prostaglandin E2 (PGE2) and IL-23-induced pathogenic IL-17, plays a crucial role in persistent inflammation and bone degradation during RA. However, the molecular mechanism of IL-23, a key cytokine, and PGE2 in the development and perpetuation of IL-17 producing effector Th17 cells is poorly understood. This review focuses on research findings that provide insight into the contribution of PGE2 and IL-23 during the development of pathogenic Th17 cells. We also highlight the key transcriptional factors required for Th17 development and therapeutic strategies to disrupt the interaction between IL-23 and IL-17 to prevent the end-organ damage in RA.

Psoriatic cutaneous inflammation promotes human monocyte differentiation into active osteoclasts, facilitating bone damage.

Psoriatic arthritis (PsA) is a chronic inflammatory arthropathy that can be associated with focal bone erosions. Psoriasis usually precedes the psoriatic arthritis onset by an average of 10 years, but this relation is not yet fully elucidated. Pro-inflammatory cytokines, such as IL-33, OPN, IL-17, and TNF-α are involved in both psoriasis and PsA pathogenesis as well as in bone homeostasis. In this study, we have demonstrated that IL-33, OPN, IL-17, and TNF-α induced the release of a wide range of pro-osteoclastogenic factors from the skin, such as RANKL, that promote monocyte differentiation in osteoclasts. The addition of osteoprotegerin, a RANKL inhibitor, to monocyte cultures treated with supernatant from stimulated skin did not completely deplete osteoclast formation, suggesting that skin produced several additional pro-osteoclastogenic mediators, which could act in a RANKL-independent manner. Moreover, we have found that RANKL serum levels as well as osteoclast number and activity in psoriatic patients with and without arthritis, was influenced by severity of cutaneous disease. Our data demonstrate that psoriatic cutaneous inflammation contributes to bone damage.

Smad-dependent mechanisms of inflammatory bone destruction.

Homeostatic bone remodelling becomes disturbed in a variety of pathologic conditions that affect the skeleton, including inflammatory diseases. Rheumatoid arthritis is the prototype of an inflammatory arthritis characterised by chronic inflammation, progressive cartilage destruction and focal bone erosions and is a prime example for a disease with disturbed bone homeostasis. The inflammatory milieu favours the recruitment and activation of osteoclasts, which have been found to be the cells that are primarily responsible for bone erosions in many animal models of inflammatory arthritis. Among the inflammatory modulators, members of the transforming growth factor (TGF)-β super family are shown to be important regulators in osteoclastogenesis with Smad-mediated signalling being crucial for inducing osteoclast differentiation. These findings have opened a new field for exploring mechanisms of osteoclast differentiation under inflammatory conditions. Recent studies have shown that the TGF-β superfamily members TGF-β1, myostatin and activin A directly regulate osteoclast differentiation through mechanisms that depend on the RANKL–RANK interplay. These growth factors transduce their signals through type I and II receptor serine/threonine kinases, thereby activating the Smad pathway. In this review, we describe the impact of inflammation-induced Smad signalling in osteoclast development and subsequently bone erosion in rheumatoid arthritis.

Animal Models of Bone Loss in Inflammatory Arthritis: from Cytokines in the Bench to Novel Treatments for Bone Loss in the Bedside-a Comprehensive Review.

Throughout life, bone is continuously remodelled. Bone is formed by osteoblasts, from mesenchymal origin, while osteoclasts induce bone resorption. This process is tightly regulated. During inflammation, several growth factors and cytokines are increased inducing osteoclast differentiation and activation, and chronic inflammation is a condition that initiates systemic bone loss. Rheumatoid arthritis (RA) is a chronic inflammatory auto-immune disease that is characterised by active synovitis and is associated with early peri-articular bone loss. Peri-articular bone loss precedes focal bone erosions, which may progress to bone destruction and disability. The incidence of generalised osteoporosis is associated with the severity of arthritis in RA and increased osteoporotic vertebral and hip fracture risk. In this review, we will give an overview of different animal models of inflammatory arthritis related to RA with focus on bone erosion and involvement of pro-inflammatory cytokines. In addition, a humanised endochondral ossification model will be discussed, which can be used in a translational approach to answer osteoimmunological questions.

Focal bone involvement in inflammatory arthritis: the role of IL17.

Conditions such as rheumatoid arthritis (RA) and spondyloarthritis (SpA, such as psoriatic arthritis, PsA, and ankylosing spondylitis, AS) are characterized by an imbalance between osteoclast (OC) bone resorption and osteoblast (OB) bone formation. The two conditions present substantial differences in bone involvement, which is probably related to the different expression of IL17 and TNFα, two cytokines that strongly promote osteoclastogenesis and focal bone erosions. TNFα is the major inflammatory cytokine in RA. It acts by both triggering OC bone erosion via the RANK-RANKL system, and suppressing OB bone formation through the overexpression of DKK1, a powerful inhibitor of the WNT bone anabolic signaling pathway. Differing from TNFα, IL17 promotes also osteogenesis, particularly at inflamed sites undergoing mechanical stress, such as entheses. Therefore, in RA, where overexpression of TNFα is higher than IL17, OC bone resorption largely prevails upon bone formation. In PsA and AS, the prevailing inflammatory cytokine is IL17, which promotes also osteogenesis. Given the prevalent involvement of entheses poor of OC, excess bone formation may even prevail over excess bone resorption. The results of clinical trials support the different pathophysiology of bone involvement in chronic arthritis. Inflammation control through anti-TNFα agents has not resulted in incomparable effects on radiographic progression and excess bone formation in both AS and PsA. Clinical trials investigating IL17 inhibitors, such as secukinumab, in patients with psoriatic disease are underway. The preliminary results on inflammation and symptoms appear positive, while long-term studies are required to demonstrate an effect on excess bone formation.

Interleukin-10 regulates the inflammasome-driven augmentation of inflammatory arthritis and joint destruction.

IntroductionActivation of the inflammasome has been implicated in the pathology of various autoinflammatory and autoimmune diseases. While the NLRP3 inflammasome has been linked to arthritis progression, little is known about its synovial regulation or contribution to joint histopathology. Regulators of inflammation activation, such as interleukin (IL)-10, may have the potential to limit the inflammasome-driven arthritic disease course and associated structural damage. Hence, we used IL-10-deficient (IL-10KO) mice to assess NLRP3 inflammasome-driven arthritic pathology.MethodsAntigen-induced arthritis (AIA) was established in IL-10KO mice and wild-type controls. Using histological and radiographic approaches together with quantitative real-time PCR of synovial mRNA studies, we explored the regulation of inflammasome components. These were combined with selective blocking agents and ex vivo investigative studies in osteoclast differentiation assays.ResultsIn AIA, IL-10KO mice display severe disease with increased histological and radiographic joint scores. Here, focal bone erosions were associated with increased tartrate-resistant acid phosphatase (TRAP)-positive cells and a localized expression of IL-1β. When compared to controls, IL-10KO synovium showed increased expression of Il1b, Il33 and NLRP3 inflammasome components. Synovial Nlrp3 and Casp1 expression further correlated with Acp5 (encoding TRAP), while neutralization of IL-10 receptor signaling in control mice caused increased expression of Nlrp3 and Casp1. In ex vivo osteoclast differentiation assays, addition of exogenous IL-10 or selective blockade of the NLRP3 inflammasome inhibited osteoclastogenesis.ConclusionsThese data provide a link between IL-10, synovial regulation of the NLRP3 inflammasome and the degree of bone erosions observed in inflammatory arthritis.Electronic supplementary materialThe online version of this article (doi:10.1186/s13075-014-0419-y) contains supplementary material, which is available to authorized users.

Zoledronate for prevention of bone erosion in tophaceous gout: a randomised, double-blind, placebo-controlled trial

ObjectivesThe osteoclast has been implicated in development of bone erosion in gout. The aim of this study was to determine whether zoledronate, a potent antiosteoclast drug, influences bone erosion in...

102 : Interleukin 10 control of the inflammasome restricts arthritic bone erosion

Members of the nucleotide-binding oligomerization domain receptor (NOD)-like receptor (NLR) family are implicated in the pathology of various auto-inflammatory and autoimmune diseases. While the NOD-like receptor family, pyrin domain containing 3 (NLRP3) inflammasome, has been linked to arthritis progression, little is known about its synovial regulation or contribution to joint histopathology. Signaling by pattern recognition receptors is often inhibited by the inflammatory cytokine interleukin (IL)-10. In antigen-induced arthritis, IL-10-deficient (IL-10KO) mice display severe disease with increased histological and radiographic joint scores. Here, focal bone erosions were associated with an increase in tartrate resistant acid phosphatase (TRAP)-positive cells and a localized expression of IL-1 β . When compared to wild type controls, mRNA from the inflamed synovium of IL-10KO mice showed increased expression of Il1b , Il33 and components of the NLRP3 inflammasome. Furthermore, synovial Nlrp3 and Caspase 1 ( Casp1) expression correlated with Acid phosphatase 5, tartrate resistance ( Acp5) (encoding TRAP) expression, while neutralization of IL-10 receptor signaling in wild type mice caused increased expression of Nlrp3 and Casp1 . In ex vivo osteoclast differentiation assays, addition of exogenous IL-10 or selective blockade of the NLRP3 inflammasome inhibited osteoclastogenesis. Thus, IL-10 regulation of the inflammasome may impact homeostatic bone turnover and limit the degree of bone erosions observed in inflammatory arthritis.

SAT0064 Is Low Bone Mineral Density in Postmenopausal Women Associated with Worse Radiological Damage in Patients with Early Rheumatoid Arthritis ?

BackgroundPostmenopausal period associated with functional change in different systems, including bone remodeling. We postulated that INITIAL low bone mineral density (BMD) s can influence on mechanism of focal bone erosion...

Assessing rheumatologists and radiologists agreement rate regarding the diagnosis of focal bone erosions and osteopenic changes using hand X-rays radiography in patients with rheumatoid arthritis

In rheumatoid arthritis, diagnosis of bone erosions and osteopenic changes in earlier stages is extremely important to the initiation of specific and more aggressive treatment to subsidize the disease, decrease morbidities, and increase patients' quality of life. In the present study, we assessed consensus rate of rheumatologists and radiologists regarding the detection of radiographic changes of hand in rheumatoid arthritis. Ninety-six adult patients with documented rheumatoid arthritis referring to our outpatient rheumatology clinic during March 2009-2010, enrolled into this cross-sectional study. Hands and wrists X-ray obtained for all patients. The films were observed by a rheumatologist and a radiologist separately, to detect focal bone erosions, periarticular osteopenic changes, and joint space losses. Agreement rates between the two specialists were assessed using the kappa test ratio. A total of 96 patients comprising 86 (89.5%) female and 10 (10.41%) male with a mean age of 48.5 ± 1.2 years (range 22-76 years old) were studied. The proportion agreement between the radiologist and rheumatologist regarding bone erosions and juxta-articular osteopenic changes was 69.7 and 84.3%, respectively. The kappa agreement coefficient for the diagnosis of bone erosions was 36% which showed significant poor agreement between two specialist (p < 0.001, proportion agreement = 69.7%). As well, the kappa of 20% for the detection of juxta-articular osteopenic changes revealed significant poor agreement between the two specialist (p < 0.047, proportion agreement = 84.3%). The results of the present study demonstrate that there is a minimal agreement between the two radiology and rheumatology specialists regarding simultaneous diagnosis of bone erosions and periarticular osteopenic changes in rheumatoid arthritis patients that emphasis requiring both specialists' X-ray report at the time of diagnosis.

Effect of sclerostin-neutralising antibody on periarticular and systemic bone in a murine model of rheumatoid arthritis: a microCT study

IntroductionPatients with chronic inflammatory diseases have increased bone loss and bone fragility and are at increased risk of fracture. Although anti-resorptive drugs are effective in blocking inflammation-induced bone loss, they are less effective at rebuilding bone. We have previously shown that treatment with sclerostin antibody (Scl-AbI) builds bone and can prevent or restore bone loss in a murine model of inflammatory bowel disease. In this study, we tested the effect of Scl-AbI in a murine model of rheumatoid arthritis (the collagen-induced arthritis model, CIA). We hypothesised that sclerostin blockade can protect and restore bone both locally and systemically without affecting progression of inflammation.MethodsCIA was induced in male DBA/1 mice, which were treated with either PBS or Scl-AbI (10 mg/kg, weekly) prophylactically for 55 days or therapeutically for 21 days (starting 14 days post onset of arthritis). Systemic inflammation was assessed by measuring the serum concentration of anti-CII IgG1, IgG2a and IgG2b by ELISA. Changes in bone mass and structure, either at sites remote from the joints or at periarticular sites, were measured using DEXA and microCT. Bone focal erosion was assessed in microCT scans of ankle and knee joints.ResultsCirculating anti-CII immunoglobulins were significantly elevated in mice with CIA and there were no significant differences in the levels of anti-CII immunoglobulins in mice treated with PBS or Scl-ABI. Prophylactic Scl-AbI treatment prevented the decrease in whole body bone mineral density (BMD) and in the bone volume fraction at axial (vertebral body) and appendicular (tibial proximal metaphysis trabecular and mid-diaphysis cortical bone) sites seen in PBS-treated CIA mice, but did not prevent the formation of focal bone erosions on the periarticular bone in the knee and ankle joints. In the therapeutic study, Scl-AbI restored BMD and bone volume fraction at all assessed sites but was unable to repair focal erosions.ConclusionsSclerostin blockade prevented or reversed the decrease in axial and appendicular bone mass in the murine model of rheumatoid arthritis, but did not affect systemic inflammation and was unable to prevent or repair local focal erosion.

Altered bone biology in psoriatic arthritis.

Psoriatic arthritis (PsA) is characterized by focal bone erosions mediated by osteoclasts at the bone–pannus junction. The bulk of research over the past decade has centered on mechanisms that underlie osteoclastogenesis along with new insights into osteoimmunology; however, recent advances that focus on steps that lead to new bone formation are beginning to emerge. New revelations about bone formation may have direct relevance to PsA given the presence of enthesophytes, syndesmophytes, and bony ankylosis frequently observed in patients with this disorder. In this review, we discuss current developments in the pathogenesis of new bone formation, novel imaging approaches to study bone remodeling and highlight innovative approaches to study the effect of inflammation on bone. Lastly, we discuss promising therapies that target joint inflammation and osteitis with the potential to mediate pathologic bone formation.

Upregulation of tumor necrosis factor receptor-associated factor 6 correlated with synovitis severity in rheumatoid arthritis

IntroductionRheumatoid arthritis (RA) is a chronic inflammatory disease leading to joint destruction and disability. Focal bone erosion is due to excess bone resorption of osteoclasts. Tumor necrosis factor receptor-associated factor 6 (TRAF6) is one of the critical mediators both in inflammatory signal pathway and differentiation and resorption activity of osteoclasts. Here we aimed to investigate TRAF6 expression in RA synovium and its correlation with histological synovitis severity and radiological joint destruction in RA.MethodsSynovitis score was determined in needle biopsied synovium from 44 patients with active RA. Synovium from nine patients with osteoarthritis (OA) and seven with orthopedic arthropathies (Orth.A) were enrolled as "less inflamed" disease controls. Serial sections were stained immunohistochemically for TRAF6 as well as CD68 (macrophage), CD3 (T cell), CD20 (B cell), CD38 (plasmocyte), CD79a (B lineage cells from pre-B cell to plasmocyte stage), and CD34 (endothelial cell). Double immunofluorescence staining of TRAF6 and CD68 were tested. Densities of positive staining cells were determined and correlated with histological disease activity (synovitis score) and radiographic joint destruction (Sharp score).ResultsTRAF6 expression was found in the intimal and subintimal area of RA synovium, with intense staining found in the endochylema and nucleus of intimal synoviocytes and subintimal inflammatory cells. Double immunofluorescence staining showed TRAF6 was expressed in most of the intimal cells and obviously expressed in CD68+ cells and some other CD68- cells in subintimal area. Synovial TRAF6 was significantly over-expressed in the RA group compared with the OA and Orth.A group (2.53 ± 0.94 vs. 0.72 ± 0.44 and 0.71 ± 0.49, P < 0.0001). Synovial TRAF6 expression in RA correlated significantly with synovitis score (r = 0.412, P = 0.006), as well as the inflammatory cell infiltration (r = 0.367, P = 0.014). Significant correlation was detected between synovial TRAF6 expression and intimal CD68+ cells, as well as the cell density of subintimal CD68+ cells, CD3+ cells, CD20+ cells, CD38+ cells, and CD79a+ cells (all P < 0.05).ConclusionsElevated synovial TRAF6 expression correlated with synovitis severity and CD68+ cell density in RA. It is, therefore, hypothesized that synovial TRAF6 is involved in the pathogenesis of synovial inflammation and osteoclast differentiation in RA.

Hamster and Murine Models of Severe Destructive Lyme Arthritis

Arthritis is a frequent complication of infection in humans with Borrelia burgdorferi. Weeks to months following the onset of Lyme borreliosis, a histopathological reaction characteristic of synovitis including bone, joint, muscle, or tendon pain may occur. A subpopulation of patients may progress to a chronic, debilitating arthritis months to years after infection which has been classified as severe destructive Lyme arthritis. This arthritis involves focal bone erosion and destruction of articular cartilage. Hamsters and mice are animal models that have been utilized to study articular manifestations of Lyme borreliosis. Infection of immunocompetent LSH hamsters or C3H mice results in a transient synovitis. However, severe destructive Lyme arthritis can be induced by infecting irradiated hamsters or mice and immunocompetent Borrelia-vaccinated hamsters, mice, and interferon-gamma- (IFN-γ-) deficient mice with viable B. burgdorferi. The hamster model of severe destructive Lyme arthritis facilitates easy assessment of Lyme borreliosis vaccine preparations for deleterious effects while murine models of severe destructive Lyme arthritis allow for investigation of mechanisms of immunopathology.

Relationship of Focal Erosions, Bone Mineral Density, and Parathyroid Hormone in Rheumatoid Arthritis

To investigate the relationship among focal bone erosions and bone mineral density (BMD), 25(OH) vitamin D (25OHD), and parathyroid hormone (PTH) values in patients with rheumatoid arthritis (RA). The study included 1191 RA patients (1014 women, 177 men, mean age 58.9 ± 11.1 yrs) participating in a multicenter, cross-sectional study. Radiographic evidence of typical bony erosions on hands or forefeet was found in 64.1% of patients. In those with bone erosions as compared to those without, mean BMD Z score values were significantly lower at both the spine (-0.74 ± 1.19 vs -0.46 ± 1.31; p = 0.05) and the hip (-0.72 ± 1.07 vs -0.15 ± 1.23; p < 0.001). In the subgroup of patients not taking vitamin D supplements, PTH levels were significantly higher in those with erosive arthritis (25.9 ± 14.0 vs 23.1 ± 11.6 pg/ml; p = 0.01); whereas the 25OHD concentrations were very similar in the 2 groups. The mean differences for BMD and PTH among the erosive and nonerosive RA remained statistically significant when values were simultaneously adjusted for all disease and mineral metabolism factors (i.e., age, sex, menopause, disease duration, Disease Activity Score 28-joint count, Health Assessment Questionnaire, activities of daily living, Steinbrocker functional state, glucocorticoid therapy, body weight, and bisphosphonate treatment). Our results suggest that the presence of bone erosions in RA correlates with low BMD levels and high PTH levels, and that these associations are independent of the degree of functional impairment and other common determinants of bone mass and mineral metabolism in adults with RA. These findings suggest that treatments to prevent bone loss or suppress PTH levels might positively affect the progression of bone erosions in RA.