Overexpression of Transmembrane TNF Drives Development of Ectopic Lymphoid Structures in the Bone Marrow and B Cell Lineage Alterations in Experimental Spondyloarthritis.

TNF is important in immune-mediated inflammatory diseases, including spondyloarthritis (SpA). Transgenic (tg) mice overexpressing transmembrane TNF (tmTNF) develop features resembling human SpA. Furthermore, both tmTNF tg mice and SpA patients develop ectopic lymphoid aggregates, but it is unclear whether these contribute to pathology. Therefore, we characterized the lymphoid aggregates in detail and studied potential alterations in the B and T cell lineage in tmTNF tg mice. Lymphoid aggregates developed in bone marrow (BM) of vertebrae and near the ankle joints prior to the first SpA features and displayed characteristics of ectopic lymphoid structures (ELS) including presence of B cells, T cells, germinal centers, and high endothelial venules. Detailed flow cytometric analyses demonstrated more germinal center B cells with increased CD80 and CD86 expression, along with significantly more T follicular helper, T follicular regulatory, and T regulatory cells in tmTNF tg BM compared with non-tg controls. Furthermore, tmTNF tg mice exhibited increased IgA serum levels and significantly more IgA+ plasma cells in the BM, whereas IgA+ plasma cells in the gut were not significantly increased. In tmTNF tg × TNF-RI-/- mice, ELS were absent, consistent with reduced disease symptoms, whereas in tmTNF tg × TNF-RII-/- mice, ELS and clinical symptoms were still present. Collectively, these data show that tmTNF overexpression in mice results in osteitis and ELS formation in BM, which may account for the increased serum IgA levels that are also observed in human SpA. These effects are mainly dependent on TNF-RI signaling and may underlie important aspects of SpA pathology.

New perspectives on traumatic bone infections.

In this paper, we review the results of previous studies and summarize the effects of various factors on the regulation of bone metabolism in traumatic bone infections. Infection-related bone destruction incorporates pathogens and iatrogenic factors in the process of bone resorption dominated by the skeletal and immune systems. The development of bone immunology has established a bridge of communication between the skeletal system and the immune system. Exploring the effects of pathogens, skeletal systems, immune systems, and antibacterials on bone repair in infectious conditions can help improve the treatment of these diseases.

[Inflammation and bone : Osteoimmunological aspects]. / Entzündung und Knochen : Osteoimmunologische Aspekte.

Microscopic fractures (so-called microcracks) or traumatic macrofractures require bone, as the basic scaffold of the human body, to have a high regenerative capability. In order to be able to provide this regenerative capability, bone is in a constant process of remodeling. This finely tuned homeostasis of bone formation and degradation can become disrupted, which leads to osteoporosis or other bone disorders. It has been shown that the immune system is substantially involved in the regulation of bone homeostasis and that chronic inflammation in particular can disturb this balance; therefore, this article reviews the osteoimmunological aspects contributing to osteoporosis and other diseases associated with bone degradation.

Th17 and Treg cells in bone related diseases.

Bone-related diseases share the process of immune response that targets bone tissue and bone marrow and then induce adverse effects on structure and function. In recent years, reciprocal relationship between immune cells and bone systems has been uncovered gradually. Regulatory T (Treg) and T helper 17 (Th17) cells are newly identified subsets of CD4+ T cells, and the balance between them is particularly essential for maintaining immune homeostasis. Accumulated data have demonstrated quantitative or functional imbalance between Th17 and Treg in bone related diseases, suggesting that Th17 and Treg cells are involved in these bone diseases. Understanding the molecular mechanisms regulating Th17 and Treg cells will create opportunities for the development of therapeutic approaches. This review will present the role of Th17 and Treg cells in the inflammatory bone diseases and bone marrow malignancies and find the potential therapeutic target for immunotherapy.

Effects of inflammation on bone: an update.

PURPOSE OF REVIEW: To present an updated summary of the relationship between inflammation and localized and generalized bone loss in the rheumatic diseases. RECENT FINDINGS: In addition to the well established role of inflammatory cytokines in promoting enhanced osteoclast function and bone loss, recent work has discovered the cytokine milieu may also inhibit osteoblast function and bone repair. The WNT and bone morphogenetic protein pathways provide molecular links between inflammation and altered bone homeostasis in chronic inflammatory states. These pathways and others have been the targets of emerging therapies for the management of inflammatory bone loss. SUMMARY: Inflammation and bone loss are linked through a number of molecular pathways. Both of these processes need to be addressed when designing an effective treatment strategy for the rheumatic diseases.

Bitter Taste Receptor as a Therapeutic Target in Orthopaedic Disorders.

Non-gustatory, extraoral bitter taste receptors (T2Rs) are G-protein coupled receptors that are expressed throughout the body and have various functional responses when stimulated by bitter agonists. Presently, T2Rs have been found to be expressed in osteoclasts and osteocytes where osteoclasts were capable of detecting bacterial quorum-sensing molecules through the T2R38 isoform. In the innate immune system, stimulating T2Rs induces anti-inflammatory and anti-pathogenic effects through the phospholipase C/inositol triphosphate pathway, which leads to intracellular calcium release from the endoplasmic reticulum. The immune cells with functional responses to T2R activation also play a role in bone inflammation and orthopaedic disorders. Furthermore, increasing intracellular calcium levels in bone cells through T2R activation can potentially influence bone formation and resorption. With recent studies finding T2R expression in bone cells, we examine the potential of targeting this receptor to treat bone inflammation and to promote bone anabolism.

Inflammation and repair mechanisms.

Although both rheumatoid arthritis (RA) and ankyosing spondylitis (AS) belong to the group of chronic inflammatory rheumatic diseases, they are quite different regarding mechanisms of inflammation and repair. While RA is an erosive destructive disease with the synovium as the primary site of inflammation, the immune response in AS takes place primarily at the cartilage/bone interface, and the pathological but also the clinical picture is determined by an until not yet well defined interaction between inflammation and new bone formation. Most recently, first insights into the molecular mechanisms between inflammation and bone destruction or new bone formation could be obtained. Key molecules involved in bone homeostasis seem to differ between RA and AS patients. While the molecules sclerostin and dickkopf 1, both inhibitors of osteoblasts, are elevated in RA they are found to be rather low in AS. It can be expected that the rapidly expanding new field of osteoimmunology will help to clarify the pathogenesis of the these two diseases with possible implications for new treatment targets.

Rheumatoid arthritis and ankylosing spondylitis - pathology of acute inflammation.

Histomorphological analysis of inflammatory lesions in rheumatoid arthritis (RA) and ankylosing spondylitis (AS) display similarities but also major differences. Ankylosing spondylitis is characterised by two key pathological findings: sacroiliac joint and spinal inflammation and new bone formation with the possible consequence of bone fusion, usually in the axial skeleton. In AS the primary site of inflammation is located at the enthesis or subchondral bone marrow with bone marrow oedema, lymphocytic infiltrates, increased osteoclast density and increased microvessel density are typical findings in acute inflammation. In RA joint inflammation has its origin in the synovial membrane of peripheral joints. Osteitis in the subchondral bone marrow reveals similar findings compared to AS and it is suggested to occur secondary to inflammation in the synovial membrane. Structural damage defines the outcome in both diseases. However, in AS it is defined by new bone formation and in RA by the destruction of cortical bone.

[What's new in internal medicine?]. / Quoi de neuf en médecine interne?

Among diagnostic progress over the last three years in internal medicine, Antisynthetase Syndrome is now more easily recognised with the diffusion of laboratory tests for research of antibodies against tRNA synthetases (Anti JO1, anti PL7, Anti PL12). In two third of cases, these antibodies are found despite absence of antinuclear antibodies. Hence, we have to search them specifically in patients with polyarthritis associated with myositis, cutaneous manifestations (Raynaud phenomenom and "mechanic'hands") and interstitial lung disease. Discovery of asymptomatic mutation in the L ferritin coding sequence help us to better understand the "unexplained" hyperferritinemia. Initially described by japonese gastroenterologists, auto immune pancreatitis in fact a part of a systemic sclerosing disease with a biochemical hallmark: in crease of a subclass of immunoglobulins G (IgG4). A new pediatric disease due to a deficiency of the interleukin1 receptor antagonist (multifocal aseptic osteitis, periostitis, stomatitis, disseminated pustulosis) help us to better understand unexplained auto inflammatory diseases. The therapeutic progress is primarily due to an explosion of biological therapies, particularly four of them very useful for internists (in an off label use) : Interleukin 1 inhibitors (anakinra, Canakinumab) to treat some auto inflammatory diseases (cryopirin associated periodic syndromes and deficency of interleukin 1 receptor antagonist), monoclonal antibody against interleukin 5 (mepolizumab) to treat some hypereosinophilic syndromes and Churg and Strauss angiitis, interleukin 6 inhibitiors to treat multifocal Castleman's disease and adult Still disease, a monoclonal antibody against vascular endothelial growth factor (Bevacizumab) to treat hereditary hemorrhagic telangiectasia.

Synovitis-acne-pustulosis-hyperostosis-osteitis syndrome and psoriatic arthritis exhibit a different immunogenetic profile.

BACKGROUND AND OBJECTIVES: Patients with psoriatic arthritis (PsA) as well as those with synovitis, acne, pustulosis, hyperostosis, osteitis (SAPHO) syndrome share some common features, and in fact, for many authors the SAPHO concept fits well into the broader concept of PsA. However, some clinical features are unique to the SAPHO syndrome, and in the other hand, these patients do not show the known association between the HLA-B27 antigen and the spondyloarthropathies. To date, there are no studies comparing the immunogenetic profile of these two conditions, so the main objective of the present report was to analyse whether or not both entities may share the same genetic basis. PATIENTS AND METHODS: All patients with SAPHO syndrome (n=25) seen in a single university hospital from 1985 to 2005 were recruited and followed up in standardised manner in order to study their main characteristics and HLA profile. The HLA-Cw6, DR and B27 antigen distribution of these cases was compared to that of 50 patients with psoriasis vulgaris, 120 with PsA, and 170 healthy blood donors. PsA patients were classified in accordance with their predominant pattern observed in the last 5 years of disease evolution. Odds ratios (OR) values were calculated to measure the strength of the association between HLA antigens and disease, while the statistical significance of the association was assessed with a two-tailed Fisher's exact test. P<0.05 values were considered significant. RESULTS: No association was found between HLA-Cw6, B27, or DR antigens, and SAPHO syndrome. HLA-Cw6 was strongly associated with psoriasis, OR 12 (95% CI: 5.6-26, p<0.0001) and PsA, OR 10 (95% CI: 5.4-19.5, p<0.0001), however this antigen was equally distributed among the three articular categories of PsA. HLA-DR4 was found under-represented in PsA patients compared to controls, OR 0.4 (95% CI: 0.2-0.7, p=0.002). HLA-DR7 correlated well with psoriatic oligoarthritis, OR 9.6 (95% CI: 2.9-28, p<0.0001), HLA-DR8 was found associated with polyarthritis, OR 6.7 (95% CI: 2-25, p=0.002), while HLA-B27 was over-represented in psoriatic spondylitis, OR 10 (95% CI: 3.3-25, p<0.0001). CONCLUSIONS: Psoriasis/PsA and SAP-HO syndrome show a different immunogenetic background, however the genetic basis of SAPHO syndrome remains unknown.

Potential Role of L-Arginine and Vitamin E Against Bone Loss Induced by Nano-Zinc Oxide in Rats.

The purpose of this study was to illustrate the effects of zinc oxide nanoparticles (ZnO-NPs) administration on bone turnover and bone resorbing agents in rats and how L-arginine (L-arg) or vitamin E (vit E) co-administrations might affect them. Fasting rats were randomly divided into four groups (n = 10): G1-normal healthy animals; G2-ZnO-NPs-exposed rats (600 mg/kg-1/day-1); G3-ZnO-NPs-exposed rats co-administrated L-arg (200 mg/kg-1/day-1); G4-ZnO-NPs-exposed rats co-administrated vit E (200 mg/kg-1/day-1). The ingredients were orally administered daily. The body weight and food consumption of rats were recorded during the administration period and the experiment continued for three consecutive weeks. The results demonstrated that ZnO-NPs administration induced bone loss in rats as manifested by reduced activity of bone alkaline phosphatase (B-ALP) and increased level of C-terminal peptide type I collagen (CTx). The increase of inflammatory markers, tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) by ZnO-NPs suggests that deleterious effects of ZnO-NPs on bone turnover were, in part, due to inflammation. Confirming to this suggestion, both L-arg and vit E reduced TNF-α and IL-6 levels and consequently decreased bone resorption as indicated by reduced serum CTx level. This study proved that ZnO-NPs can induce bone turnover, which may be reduced by L-arg or vit.E co-administration, partly by anti-inflammatory mechanism.

CypD-mPTP axis regulates mitochondrial functions contributing to osteogenic dysfunction of MC3T3-E1 cells in inflammation.

Bone is a dynamic organ, the bone-forming osteoblasts and bone-resorbing osteoclasts form the physiological basis of bone remodeling process. During pathological process of numerous inflammatory diseases, these two aspects are uncoupled and the balance is usually tipped in favor of bone destruction. Evidence suggests that the inflammatory destruction of bone is mainly attributed to oxidative stress and is closely related to mitochondrial dysfunction. The mechanisms underlying osteogenic dysfunction in inflammation still need further investigation. Reactive oxygen species (ROS) is associated with mitochondrial dysfunction and cellular damage. Here, we reported an unexplored role of cyclophilin D (CypD), the major modulator of mitochondrial permeability transition pore (mPTP), and the CypD-mPTP axis in inflammation-induced mitochondrial dysfunction and bone damage. And the protective effects of knocking down CypD by siRNA interference or the addition of cyclosporin A (CsA), an inhibitor of CypD, were evidenced by rescued mitochondrial function and osteogenic function of osteoblast under tumor necrosis factor-α (TNF-α) treatment. These findings provide new insights into the role of CypD-mPTP-dependent mitochondrial pathway in the inflammatory bone injury. The protective effect of CsA or other moleculars affecting the mPTP formation may hold promise as a potential novel therapeutic strategy for inflammation-induced bone damage via mitochondrial pathways.

Targeting cytokines to inflammation sites.

To increase the half-life of a cytokine and target its activation specifically to disease sites, we have engineered a latent cytokine using the latency-associated protein (LAP) of transforming growth factor-beta 1 (TGF-beta 1) fused via a matrix metalloproteinase (MMP) cleavage site to interferon (IFN)-beta at either its N or C terminus. The configuration LAP-MMP-IFN-beta resembles native TGF-beta and lacks biological activity until cleaved by MMPs, whereas the configuration IFN-beta-MMP-LAP is active. LAP provides for a disulfide-linked shell hindering interaction of the cytokine with its cellular receptors, conferring a very long half-life of 55 h in vivo. Mutations of the disulfide bonds in LAP abolish this latency. Samples of cerebrospinal fluid (CSF) or synovial fluid from patients with inflammatory diseases specifically activate the latent cytokine, whereas serum samples do not. Intramuscular injection in arthritic mice of plasmid DNA encoding these constructs demonstrated a greater therapeutic effect of the latent as compared to the active forms.

A genetic approach to inactivating chemokine receptors using a modified viral protein.

We have developed a genetic system, called degrakine, that specifically and stably inactivates chemokine receptors (CKR) by redirecting the ability of the HIV-1 protein, Vpu, to degrade CD4 in the endoplasmic reticulum (ER) via the host proteasome machinery. To harness Vpu's proteolytic targeting capability to degrade new receptors, we fused a chemokine with the C terminal region of Vpu. The fusion protein, or degrakine, accumulates in the ER, trapping and functionally inactivating its target CKR. We have demonstrated that degrakines based on SDF-1 (CXCL12), MDC (CCL22) and RANTES (CCL5) specifically inactivate their respective receptor functions. Using a retroviral vector expressing the SDF-1 degrakine, we have established that CXCR4 is required for the homing of hematopoietic stem/progenitor cells (HSPC) to the bone marrow immediately after transplantation. Thus the degrakine provides an effective genetic tool to dissect receptor functions in a number of biological systems in vitro and in vivo.

Biofilm and Osteitis in Refractory Chronic Rhinosinusitis.

Our understanding of chronic rhinosinusitis (CRS) show biofilm and osteitis play a role in the disease's pathogenesis and refractory. Studies point to its role in pathogenesis and poor prognosis. Outside the research laboratory, biofilm detection remains difficult and specific treatment remains elusive. It is believed that osteitis is a nidus of inflammation and occurs more commonly in patients with refractory CRS. However, osteitis may be exacerbated by surgery and a marker of refractory disease, not a causative agent. Surgery remains the mainstay treatment for biofilm and osteitis with mechanical disruption and removal of disease load providing the most effective treatment.

Interferon-gamma-dependent Immunity in Bacillus Calmette-Guérin Vaccine Osteitis Survivors.

BACKGROUND: Inborn errors of interferon-gamma (IFN-γ)-mediated immunity underlie disseminated disease caused by Mycobacterium bovis Bacillus Calmette-Guérin (BCG) live vaccines. We hypothesized that some patients with osteitis after BCG vaccination may have an impaired IFN-γ immunity. Our aim was to investigate interleukin (IL)-12 and IFN-γ ex vivo production stimulated with BCG and BCG + IFN-γ or BCG + IL-12, respectively, in BCG osteitis survivors. METHODS: Fresh blood samples were collected from 132 former BCG osteitis Finnish patients now aged 21-49 years, and IL-12 and IFN-γ were measured in cell cultures with and without stimulation with BCG and with BCG + IFN-γ or BCG + IL-12, respectively. As a pilot study, known disease-causing genes controlling IFN-γ immunity (IFNGR1, IFNGR2, STAT1, IL12B, IL12RB1, ISG15, IRF8, NEMO and CYBB) were investigated in 20 selected patients by whole exome sequencing. RESULTS: By the limit of <5th percentile, ex vivo IL-12 concentration and increase in concentration was low in 5 and ex vivo IFN-γ concentration and increase in concentration was low in 6 patients (including 2 samples with both IL-12 and IFN-γ findings). By the limit of <10th percentile, an additional 6 and 4 patients were, respectively, detected (including 2 samples with both findings). With 2 exceptions, low concentrations and low increases in concentrations picked-up the same cases. Mutations in known disease-causing IFN-γ-related genes were not found in any of these patients. CONCLUSION: These findings call for searching of mutations in new genes governing IFN-γ-dependent immunity to live BCG vaccine.

MRI-detected osteitis is not associated with the presence or level of ACPA alone, but with the combined presence of ACPA and RF.

BACKGROUND: In rheumatoid arthritis (RA) bone marrow edema (BME, osteitis) and anti-citrullinated protein antibodies (ACPA) are associated with radiographic progression. ACPA have been associated with BME, but it is unknown if this association is confined to ACPA and BME. We performed cross-sectional analysis of the association of ACPA, rheumatoid factor (RF) and anti-carbamylated protein (anti-CarP) antibodies with BME and other types of inflammation (synovitis, tenosynovitis) detected by magnetic resonance imaging (MRI). METHODS: Disease-modifying antirheumatic drug (DMARD)-naïve patients with early arthritis (n = 589), included in the Leiden Early Arthritis Clinic cohort, underwent contrast-enhanced 1.5 T MRI of unilateral wrist, metacarpophalangeal and metatarsophalangeal-joints at baseline. BME, synovitis and tenosynovitis were scored by two readers. ACPA, rheumatoid factor (RF) and anti-CarP were determined at baseline. RESULTS: In univariable analyses ACPA-positive patients had higher BME scores than ACPA-negative patients (median 4.5 vs. 2.0, p < 0.001), but not more synovitis and tenosynovitis. Also RF (median 3.75 vs. 2.0, p < 0.001) and anti-CarP antibodies (median 3.5 vs. 2.5, p = 0.012) were associated with higher BME scores. Because the autoantibodies were concomitantly present, analyses were stratified for the presence of different autoantibody combinations. ACPA-positive (ACPA+), RF-negative (RF-), anti-CarP-negative (anti-CarP-) patients did not have higher BME-scores than ACPA-negative (ACPA-), RF-, anti-CarP- patients. However ACPA+, RF-positive (RF+), anti-CarP- patients and ACPA+, RF+, anti-CarP-positive (anti-CarP+) patients had higher BME scores than ACPA-, RF-, anti-CarP- patients (median 5.0 and 4.5 vs. 2.0, p < 0.001 and p < 0.001). ACPA levels were not associated with BME scores. Analyses within RA- and UA-patients revealed similar results. CONCLUSIONS: The presence of ACPA alone or ACPA level was not statistically significantly associated with BME scores, but the combined presence of ACPA and RF was associated with more BME. This suggests an additive role of RF to ACPA in mediating osteitis.

Leukocytes Enhance Inflammatory and Catabolic Degenerative Changes in the Intervertebral Disc After Endplate Fracture In Vitro Without Infiltrating the Disc.

STUDY DESIGN: An established rabbit intervertebral disc (IVD)/endplate explant fracture model was extended with physiologic post-traumatic dynamic loading (PTDL) and coculturing of peripheral blood mononuclear cells (PBMCs). OBJECTIVE: The aim of this study was to quantify the effects of PTDL and of cocultured PBMCs on post-traumatic disc degeneration (DD) and to determine whether PTDL facilitates homing of PBMC to fractured IVD/endplates. SUMMARY OF BACKGROUND DATA: DD is associated with endplate fracture. In vivo studies suggest a key role of immune cells in the pathogenesis of DD. However, the complexity of in vivo systems impedes the investigation of single factors governing the pathogenesis. METHODS: Seventy-two IVD/endplate specimens were divided into 4 groups. In group A, endplate fractures were induced with a high-velocity axial load and exposed to PTDL in coculture with PBMCs for 14 days. Group A was compared with 3 control groups, with single-factor removal, in order to assess the relative contribution of PTDL (group B), PBMCs (group C), and endplate fracture (group D) to the biological response of the IVD. Disc gene transcription and serum nitric oxide (NO) serum concentration were measured to investigate differences in anabolism, catabolism, and inflammatory response between the groups. Changes in matrix composition and disc structure were assessed histologically. RESULTS: PBMCs did not home to fractured IVDs, with or without PTDL. Group A compared with group D showed an enhanced transcription of anabolic, catabolic, and pro-inflammatory genes during the entire experiment, and an increased NO concentration for the first 3 days. Changes typical for DD were also found in histological sections. Group A compared with group C showed significant increases in catabolic and pro-inflammatory gene transcription after at least 7 days. No differences were found between groups A and B. CONCLUSION: Trauma induces degenerative changes; PTDL neither aggravates nor ameliorates this response. Although PBMCs do not infiltrate the disc, they aggravate the degenerative changes. LEVEL OF EVIDENCE: N/A.

Inflammation, Bone Healing, and Anti-Inflammatory Drugs: An Update.

Fracture healing is a unique multifaceted process requiring the presence of cells, molecular mediators, and angiogenic factors. The state of inflammation dominates the initial phase, but the ideal magnitude and duration of the process for an optimal outcome remains obscure. Biological response modifiers, such as platelet-rich plasma (PRP) preparations, have been used to reconstitute the desirable early inflammatory state, but the results obtained remain inconclusive. Ongoing research to characterize and quantify the inflammatory response after bone fracture is essential in order to better understand the molecular insights of this localized reaction and to expand our armamentarium in the management of patients with an impaired fracture healing response. Non-steroidal anti-inflammatory drugs frequently administered for analgesia after trauma procedures continue to be a cause of concern for a successful bone repair response.