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Journal: Arthritis research & therapy

172

Effective treatment of reactive arthritis would ideally achieve both control of inflammation and eradication of persisting arthritogenic pathogens. We use a model of experimental Chlamydia trachomatis-induced arthritis (CtIA) to evaluate the effectiveness of nafamostat mesilate (NM), a serine protease inhibitor with complement-modifying effects and anticoagulant properties. To date clinical use of NM has largely been in Asia and has been primarily confined to inflammatory states such as pancreatitis.

Concepts: Clinical trial, Microbiology, Effect, Effectiveness, Serine protease, Protease, Reactive arthritis, Mesylate

171

Methotrexate (MTX) exerts at least part of its anti-inflammatory effects through adenosine receptors (ADOR). The aims of this study were to determine the expression of all four adenosine receptor genes (ADORA1, ADORA2A, ADORA2B, ADORA3 and ADORA3variant) in rheumatoid synovial tissue and any influence of MTX exposure on this expression. Furthermore, we investigated whether polymorphisms within ADORA3 were associated with response and/or adverse effects associated with MTX.

Concepts: Rheumatoid arthritis, Adenosine receptor, Adenosine, Adenosine A2A receptor, Adenosine A1 receptor, Adenosine receptors

142

The aim was to describe the regulatory B and T cells (Breg and Treg) and T helper 17 (Th17) lymphocytes before and under treatment with biologic drugs, and to assess their potential predictive value as biomarkers of response in rheumatoid arthritis (RA).

Concepts: White blood cell, B cell, Rheumatoid arthritis, Rheumatology, T helper cell, T cells, Thymus, Human cells

141

B cell depletion with rituximab (RTX) is approved for treatment of rheumatoid arthritis (RA) and ANCA-associated vasculitides (AAV). Recently, RTX has been shown to be effective in AAV maintenance therapy, but an optimal RTX treatment schedule is unknown and the time to B cell repopulation after RTX has not been studied.

Concepts: Blood, Inflammations, Rheumatoid arthritis, Rheumatology, Vasculitis, Arthritis, Connective tissue

59

There is currently no blood-based test for detection of early-stage osteoarthritis (OA) and the anti-cyclic citrullinated peptide (CCP) antibody test for rheumatoid arthritis (RA) has relatively low sensitivity for early-stage disease. Morbidity in arthritis could be markedly decreased if early-stage arthritis could be routinely detected and classified by clinical chemistry test. We hypothesised that damage to proteins of the joint by oxidation, nitration and glycation, and with signatures released in plasma as oxidized, nitrated and glycated amino acids may facilitate early-stage diagnosis and typing of arthritis.

Concepts: Antibody, Protein, Amino acid, Acid, Rheumatoid arthritis, Osteoarthritis, Nitrogen, Arthritis

28

INTRODUCTION: Among various lupus renal vascular changes, thrombotic microangiopathy (TMA) presented with most severe clinical manifestations and high mortality. The pathogenesis of TMA in systemic lupus erythematosus (SLE) was complicated. The aim of this study was to assess clinical manifestations, laboratory characteristics, pathological features and risk factors for clinical outcomes of lupus nephritis patients co-existing with renal TMA in a large cohort in China. METHODS: Clinical and renal histopathological data of 148 patients with biopsy-proven lupus nephritis were retrospectively analyzed. Serum complement factor H, ADAMTS-13 activity, antiphospholipid antibodies and C4d deposition on renal vessels were further detected and analyzed. RESULTS: In the 148 patients with lupus nephritis, 36 patients were diagnosed as co-existing with renal TMA based on pathological diagnosis. Among the 36 TMA patients, their clinical diagnoses of renal TMA were as followings: 2 patients combining with thrombotic thrombocytopenic purpura-hemolytic uremic syndrome, 2 patients combining with anti-phospholipid syndrome, 2 patients with malignant hypertension, 1 patient with scleroderma and the other 29 patients presenting with isolated renal TMA. Compared with non-renal TMA group, patients with renal TMA had significantly higher urine protein (7.09+/-4.64 vs. 4.75+/-3.13 g/24h, P=0.007) and serum creatinine (159, 86-215 vs. 81, 68-112 mumol/l, P<0.001), higher scores of total activity indices (AI) (P<0.001), endocapillary hypercellularity (P<0.001), subendothelial hyaline deposits (P=0.003), interstitial inflammation (P=0.005), glomerular leukocyte infiltration (P=0.006), total chronicity indices (CI) (P=0.033), tubular atrophy (P=0.004) and interstitial fibrosis (P=0.018). Patients with renal TMA presented with poorer renal outcome (P=0.005) compared with non-TMA group. Renal TMA (hazard ratio (HR): 2.772, 95% confidence interval: 1.009-7.617, P=0.048) was an independent risk factor for renal outcome in patients with lupus nephritis. The renal outcome was poorer for those with both C4d deposition and decreased serum complement factor H in TMA group (P=0.007). CONCLUSIONS: There were various causes of renal TMA in lupus nephritis. Complement over-activation via both classical and alternative pathways might play an important role in the pathogenesis of renal TMA in lupus nephritis.

Concepts: Immune system, Rheumatology, Systemic lupus erythematosus, Glomerulonephritis, Complement system, Thrombocytopenia, Lupus nephritis, Antiphospholipid syndrome

28

INTRODUCTION: Fibrosis in scleroderma is associated with collagen deposition and myofibroblast accumulation. Peroxisome proliferator activated receptor gamma (PPAR-gamma), a master regulator of adipogenesis, inhibits profibrotic responses induced by transforming growth factor-SZ (TGF-beta), and its expression is impaired in scleroderma. The roles of adiponectin, a PPAR-gamma regulated pleiotropic adipokine, in regulating fibroblasts response and in mediating the effects of PPAR-gamma are unknown. METHODS: Regulation of fibrotic gene expression and TGF-SZ signaling by adiponectin and adenosine monophosphate protein-activated (AMP) kinase agonists were examined in normal fibroblasts in monolayer cultures and in 3-dimension skin equivalents. AdipoR1/2 expression on skin fibroblasts was determined by real-time qPCR. Gene expression changes were examined at the genome-wide level using microarrays. RESULTS: Adiponectin, an adipokine directly regulated by PPAR-gamma, acts as a potent anti-fibrotic signal in normal and scleroderma fibroblasts that abrogates the stimulatory effects of diverse fibrotic stimuli and reduces elevated collagen gene expression in scleroderma fibroblasts. Adiponectin responses are mediated via AMP kinase, a fuel-sensing cellular enzyme that is necessary and sufficient for down-regulation of fibrotic genes by blocking canonical Smad signaling. Moreover, we demonstrate that endogenous adiponectin accounts, at least in part, for the anti-fibrotic effects exerted by ligands of PPAR-gamma. CONCLUSIONS: These findings reveal a novel link between cellular energy metabolism and extracellular matrix homeostasis converging on AMP kinase. Since the levels of adiponectin as well as its receptor are impaired in scleroderma patients with progressive fibrosis, the present results suggest a potential role for defective adiponectin expression or function in progressive fibrogenesis in scleroderma and other chronic fibrosing conditions. Restoring the adiponectin signaling axis in fibroblasts might therefore represent a novel pharmacological approach to controlling fibrosis.

Concepts: DNA, Protein, Gene, Signal transduction, Adenosine triphosphate, Peroxisome proliferator-activated receptor, Fibrosis, AMP-activated protein kinase

28

INTRODUCTION: The largest genetic risk to develop rheumatoid arthritis (RA) arises from a group of alleles of the HLA DRB1 locus (“shared epitope”, SE). Over 30 non-HLA single nucleotide polymorphisms (SNPs) predisposing to disease have been identified in Caucasians, but they have never been investigated in West/Central Africa. We previously reported a lower prevalence of the SE in RA patients in Cameroon compared to European patients and aimed in the present study to investigate the contribution of Caucasian non-HLA RA SNPs to disease susceptibility in Black Africans. METHODS: RA cases and controls from Cameroon were genotyped for Caucasian RA susceptibility SNPs using Sequenom MassArray technology. Genotype data was also available for 5024 UK cases and 4281 UK controls and for 119 Yoruba individuals in Ibadan, Nigeria (YRI, HapMap). A Caucasian aggregate genetic-risk score (GRS) was calculated as the sum of the weighted risk-allele counts. RESULTS: After genotyping quality control, data on 28 Caucasian non-HLA susceptibility SNPs was available in 43 Cameroonian RA cases and 44 controls. The minor allele frequencies (MAF) were tightly correlated between Cameroonian controls and YRI individuals (correlation coefficient 93.8%, p=1.7E-13), and they were pooled together. There was no correlation between MAF of UK and African controls; 13 markers differed by more than 20%. The MAF for markers at PTPN22, IL2RA, FCGR2A and IL2/IL21 was below 2% in Africans. The GRS showed a strong association with RA in the UK. However, the GRS did not predict RA in Africans (OR=0.71, 95% CI 0.29 - 1.74, p=0.456). Random sampling from the UK cohort showed that this difference in association is unlikely to be explained by small sample size or chance, but is statistically significant with p<0.001. CONCLUSIONS: The MAF of non-HLA Caucasian RA susceptibility SNPs are different between Caucasians and Africans and several polymorphisms are barely detectable in West/Central Africa. The genetic risk of developing RA conferred by a set of 28 Caucasian susceptibility SNPs is significantly different between the UK and Africa with p<0.001. Taken together, these observations strengthen the hypothesis that the genetic architecture of RA susceptibility is different in different ethnic backgrounds.

Concepts: Genetics, Allele, Sample size, Rheumatoid arthritis, Single-nucleotide polymorphism, Genetic genealogy, Genotyping, Minor allele frequency

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INTRODUCTION: Platelet-rich plasma (PRP) is a fraction of plasma in which several growth factors are concentrated at high levels. The active soluble releasate isolated following platelet activation of PRP (PRP-releasate) has been demonstrated to stimulate the metabolism of IVD cells in vitro. The in vivo effect of PRP-releasate on degenerated IVD remains unknown. The purpose of this study was to determine the reparative effects of autologous PRP-releasate on degenerated intervertebral discs (IVDs). METHODS: To induce disc degeneration, New Zealand white rabbits (n=12) received anular puncture in two noncontiguous discs. Autologous PRP and PPP (platelet-poor plasma) were isolated from fresh blood using two centrifugation techniques. Four weeks after the initial puncture, releasate isolated from clotted PPP or PRP (PPP- or PRP-releasate), or phosphate-buffered saline (PBS; control) was injected into the punctured discs. Disc height, magnetic resonance imaging (MRI) T2-mapping and histology were assessed. RESULTS: Anular puncture produced a consistent disc narrowing within four weeks. PRP-releasate induced a statistically significant restoration of disc height (PRP vs. PPP and PBS, p<0.05). In T2-quantification, the mean T2-values of the nucleus pulposus (NP) and anulus fibrosus (AF) of the discs were not significantly different among the three treatment groups. Histologically, the number of chondrocyte-like cells was significantly higher in the discs injected with PRP-releasate compared to that with PBS. CONCLUSIONS: The administration of active PRP-releasate induced a reparative effect on rabbit degenerated IVDs. The results of this study suggest that the use of autologous PRP-releasate is safe and can lead to a clinical application for IVD degeneration.

Concepts: Spinal disc herniation, Statistical significance, In vivo, Nuclear magnetic resonance, Magnetic resonance imaging, In vitro, Intervertebral disc, Rabbit

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Common variable immunodeficiency (CVID) describes a heterogeneous subset of hypogammaglobulinemias of unknown etiology. Typically, patients present with recurrent bacterial infections of the respiratory and gastrointestinal tract. A significant proportion of CVID patients develops additional autoimmune, inflammatory or lymphoproliferative complications. CVID is the most frequent symptomatic primary immunodeficiency encountered in adults. Informative monogenetic defects have been found in single patients and families but in most cases the pathogenesis is still elusive. Numerous immunological studies have demonstrated phenotypic and functional abnormalities of T cells, B cells and antigen-presenting cells. A hallmark is the impaired memory B-cell formation that has been taken advantage of for classifying CVID patients. Clinical multi-center studies have demonstrated a correlation between immunological markers and clinical presentation. Long-term outcome is significantly influenced by delay of diagnosis and treatment and the presence of chronic inflammatory complications. While immunoglobulin replacement therapy plus antibiotics can control infections in most cases, patients with non-infectious inflammatory complications such as granulomatous inflammation, interstitial lung disease, inflammatory bowel disease, lymphoproliferation and developing malignancies still represent a therapeutic challenge. In this review we provide a systematic overview of the immunological, clinical, diagnostic and therapeutic aspects of CVID and highlight recent developments in these fields.

Concepts: Immune system, Inflammation, Lymphocyte, Protein, Medicine, Bacteria, Immunodeficiency, Primary immunodeficiency