The ank gene story

The underlying molecular defect resulting in the abnormal calcification observed in ank/ank mice has been identified. The responsible nonsense mutation affects the protein product of ank, resulting in diminished production of extracellular inorganic pyrophosphate, an important inhibitor of nucleation and of the growth of apatite crystals. The ank gene product is one of several cell membrane proteins, including ectonucleoside triphosphate pyrophosphohydrolase enzymes and alkaline phosphatase, that regulate extracellular inorganic pyrophosphate levels and thereby regulate mineralization.     

Microcytosis in ank/ank mice and the role of ANKH in promoting erythroid differentiation

Progressive ankylosis (Ank and the human homolog, ANKH) is a transmembrane protein which regulates transport of inorganic pyrophosphate (PPi). ank/ank mice with a mutated ank gene, have calcification and bone ankylosis of the affected joints. In the course of studying these mutant mice, we found that they have microcytosis. These mutant mice have lower mean red blood cell volume (MCV) and lower hemoglobin content in red cells (mean corpuscular hemoglobin, MCH) than normal mice. Using quantitative real-time PCR analysis, we showed that Ank was expressed in the E/Meg bipotent precursor, BFU-E, CFU-E, but there was no Ank expression in the hemoglobinizing erythroblasts. Stable ANKH transfectants in K562 cells highly expressed two immature erythroid cell markers, E-cadherin and endoglin. Enhanced Erythropoietin (Epo) expression and downregulation of SHP-1 were detected in these transfectants. Consequently, the autocrine Epo-EpoR signaling pathway was activated, as evidenced by higher p-Tyr JAK2, p-Tyr EpoR and p-Tyr STAT5B in the ANKH transfectants. Our results revealed a novel function of ANKH in the promotion of early erythroid differentiation in K562 cells. We also showed that ank/ank mice have lower serum levels of Epo than the normal littermates, and this is the likely cause of microcytosis in these mutant mice.     

Increased risk of temporomandibular joint closed lock: a case-control study of ANKH polymorphisms

Objectives

This study aimed to carry out a histological examination of the temporomandibular joint (TMJ) in ank mutant mice and to identify polymorphisms of the human ANKH gene in order to establish the relationship between the type of temporomandibular disorders (TMD) and ANKH polymorphisms.

Materials and Methods

Specimens from the TMJ of ank mutant and wild-type mice were inspected with a haematoxylin and eosin staining method. A sample of 55 TMD patients were selected. Each was examined with standard clinical procedures and genotyping techniques.

Results

The major histological finding in ank mutant mice was joint space narrowing. Within TMD patients, closed lock was more prevalent among ANKH-OR homozygotes (p = 0.011, OR = 7.7, 95% CI 1.6–36.5) and the elder (p = 0.005, OR = 2.4, 95% CI 1.3–4.3).

Conclusions

Fibrous ankylosis was identified in the TMJ of ank mutant mice. In the human sample, ANKH-OR polymorphism was found to be a genetic marker associated with TMJ closed lock. Future investigations correlating genetic polymorphism to TMD are indicated.     

Chondrocalcinosis is common in the absence of knee involvement

Introduction

We aimed to describe the distribution of radiographic chondrocalcinosis (CC) and to examine whether metacarpophalangeal joint (MCPJ) calcification and CC at other joints occurs in the absence of knee involvement.

Methods

This was a cross-sectional study embedded in the Genetics of Osteoarthritis and Lifestyle study (GOAL). All participants (n = 3,170) had radiographs of the knees, hands, and pelvis. These were scored for radiographic changes of osteoarthritis (OA), for CC at knees, hips, symphysis pubis, and wrists, and for MCPJ calcification. The prevalence of MCPJ calcification and CC overall, at each joint, and in the presence or absence of knee involvement, was calculated.

Results

The knee was the commonest site of CC, followed by wrists, hips, and symphysis pubis. CC was more likely to be bilateral at knees and wrists but unilateral at hips. MCPJ calcification was usually bilateral, and less common than CC at knees, hips, wrists, and symphysis pubis. Unlike that previously reported, CC commonly occurred without any knee involvement; 44.4% of wrist CC, 45.9% of hip CC, 45.5% of symphysis pubis CC, and 31.3% of MCPJ calcification occurred in patients without knee CC. Those with meniscal or hyaline articular cartilage CC had comparable ages (P = 0.21), and neither preferentially associated with fibrocartilage CC at distant joints.

Conclusions

CC visualized on a plain radiograph commonly occurs at other joints in the absence of radiographic knee CC. Therefore, knee radiographs alone are an insufficient screening test for CC. This has significant implications for clinical practice, for epidemiologic and genetic studies of CC, and for the definition of OA patients with coexistent crystal deposition.     

Inhibition of inflammation but not ankylosis by glucocorticoids in mice: further evidence for the entheseal stress hypothesis

Introduction

Studies in the spontaneous ankylosis model in aging male DBA/1 mice and in patients with ankylosing spondylitis provide evidence that inflammation and new tissue formation leading to joint or spine ankylosis are likely linked but largely uncoupled processes. We previously proposed the ''entheseal stress'' hypothesis that defines microdamage or cell stress in the enthesis as a trigger for these disease processes. Here, we further investigated the relationship between inflammation and ankylosis by focusing on the early phase of the spontaneous arthritis model.

Methods

Aging male DBA/1 mice from different litters were caged together at the age of ten weeks and studied for signs of arthritis. A group of DBA/1 mice were treated daily with dexamethasone (0.5 μg/g body weight). Severity of disease was assessed by histomorphology and by positron emission tomography (PET) using 2-[¹⁸F]fluoro-2-deoxy-D-glucose (¹⁸F-FDG) as a tracer. Bone loss in dexamethasone-treated or control mice was determined by in vivo dual-energy X-ray absorptiometry. Chemokine gene expression was studied ex vivo in dissected paws and in vitro in mesenchymal cells (periosteal and bone marrow stromal cells) by quantitative real-time PCR in the presence or absence of bone morphogenetic protein 2 (BMP2) and dexamethasone.

Results

Dexamethasone treatment did not affect incidence or severity of ankylosis, but led to an expected reduction in inflammation in the paws at week 15 as measured by PET tracer uptake. Treatment with dexamethasone negatively affected bone mineral density. Chemokines attracting neutrophils and lymphocytes were expressed in affected paws. In vitro, BMP2 stimulation upregulated chemokines in different mesenchymal joint-associated cell types, an effect that was inhibited by dexamethasone.

Conclusions

BMP signaling may be a trigger for both inflammation and ankylosis in the spontaneous model of ankylosing enthesitis. The lack of inhibition by glucocorticoids on new bone formation while causing systemic bone loss highlights the paradoxical simultaneous loss and gain of bone in patients with ankylosing spondylitis.     

The ank gene story

The underlying molecular defect resulting in the abnormal calcification observed in ank/ank mice has been identified. The responsible nonsense mutation affects the protein product of ank, resulting in diminished production of extracellular inorganic pyrophosphate, an important inhibitor of nucleation and of the growth of apatite crystals. The ank gene product is one of several cell membrane proteins, including ectonucleoside triphosphate pyrophosphohydrolase enzymes and alkaline phosphatase, that regulate extracellular inorganic pyrophosphate levels and thereby regulate mineralization.     

Circulating mediators of bone remodeling in psoriatic arthritis: implications for disordered osteoclastogenesis and bone erosion

Introduction

Rheumatoid arthritis (RA) is a systemic disease manifested by chronic inflammation in multiple articular joints, including the knees and small joints of the hands and feet. We have developed a unique modification to a clinically accepted method for delivering therapies directly to the synovium. Our therapy is based on our previous discovery of an analog peptide (A9) with amino acid substitutions made at positions 260 (I to A), 261 (A to B), and 263 (F to N) that could profoundly suppress immunity to type II collagen (CII) and arthritis in the collagen-induced arthritis model (CIA).

Methods

We engineered an adenoviral vector to contain the CB11 portion of recombinant type II collagen and used PCR to introduce point mutations at three sites within (CII_{124-402, 260A, 261B, 263D}), (rCB11-A9) so that the resulting molecule contained the A9 sequence at the exact site of the wild-type sequence.

Results

We used this construct to target intra-articular tissues of mice and utilized the collagen-induced arthritis model to show that this treatment strategy provided a sustained, local therapy for individual arthritic joints, effective whether given to prevent arthritis or as a treatment. We also developed a novel system for in vivo bioimaging, using the firefly luciferase reporter gene to allow serial bioluminescence imaging to show that luciferase can be detected as late as 18 days post injection into the joint.

Conclusions

Our therapy is unique in that we target synovial cells to ultimately shut down T cell-mediated inflammation. Its effectiveness is based on its ability to transform potential inflammatory T cells and/or bystander T cells into therapeutic (regulatory-like) T cells which secrete interleukin (IL)-4. We believe this approach has potential to effectively suppress RA with minimal side effects.     

A systematic critical review on MRI in spondyloarthritis

Introduction

Magnetic resonance imaging (MRI) has been proven capable of showing inflammatory and structural changes in patients with spondyloarthritis (SpA) and has become widely used in the diagnosis of SpA. Despite this, no systematic reviews evaluate the diagnostic utility of MRI for SpA. Therefore, the objective of this systematic review was to determine the evidence for the utility of MRI in the clinical diagnosis of SpA. The aims were to identify which MRI findings are associated with the diagnosis of SpA and to quantify this association.

Methods

MEDLINE and EMBASE were electronically searched. Inclusion criteria were cross-sectional or longitudinal case-control or cohort MRI studies. The studies required a group with either SpA or inflammatory back pain (IBP) and a non-case group without SpA or IBP. Each group required a minimum of 20 participants. The included articles had to report results containing raw numbers suitable for the construction of two-by-two tables or report results by sensitivity and specificity for cross-sectional studies or odds ratios, relative risk ratios, or likelihood ratios for longitudinal studies. Method quality was assessed by using criteria based on the QUADAS tool.

Results

In total, 2,395 articles were identified in MEDLINE and EMBASE before November 2011. All articles were reviewed by title and abstract. Seventy-seven articles were reviewed by full text, and 10 met the inclusion criteria. Two were considered of high quality: one evaluated the sacroiliac joints, and the other, the spine. Because of the small number of high-quality studies, a meta-analysis was not performed. The two high-quality studies found a positive association between MRI findings (bone marrow edema, erosions, fat infiltrations, global assessment of sacroiliitis, and ankylosis) and the diagnosis of IBP and SpA.

Conclusion

In this review, several MRI findings were found to be associated with SpA. However, because of the small number of high-quality studies, the evidence for the utility of MRI in the diagnosis of SpA must be considered limited. Therefore, caution should be taken to ensure that inflammatory and structural MRI findings are not interpreted as being more specific for SpA than is supported by research.     

Continuous Cyclic Mechanical Tension Increases Ank Expression in Endplate Chondrocytes Through the TGF-β1 and p38 Pathway

The normal ANK protein has a strong influence on anti-calcification. It is known that TGF-β1 is also able to induce extracellular inorganic pyrophosphate (ePPi) elaboration via the TGF-β1-induced ank gene expression and the mitogen-activated protein kinase (MAPK) signaling acts as a downstream effector of TGF-β1. We hypothesized that the expression of the ank gene is regulated by mechanics through TGF-β1-p38 pathway. In this study, we investigated the mechanism of short-time mechanical tension-induced ank gene expression. We found that the continuous cyclic mechanical tension (CCMT) increased the ank gene expression in the endplate chondrocytes, and there was an increase in the TGF-β1 expression after CCMT stimulation. The ank gene expression significantly increased when treated by TGF-β1 in a dose-dependent manner and decreased when treated by SB431542 (ALK inhibitor) in a dose-dependent manner. Our study results indicate that CCMT-induced ank gene expressions may be regulated by TGF-β1 and p38 MAPK pathway.Key words: Continuous cyclic mechanical tension (CCMT), Endplate chondrocytes, ank, TGF-β1, p38     

Association of single-nucleotide polymorphisms in RHOB and TXNDC3 with knee osteoarthritis susceptibility: two case-control studies in East Asian populations and a meta-analysis

Introduction

Conflicting findings on the association of single nucleotide polymorphisms (SNPs) in RHOB and TXNDC3 with susceptibility to knee osteoarthritis (OA) have been reported in European Caucasians. To examine the associations of these SNPs with OA in East Asian populations and to evaluate their global significance, we conducted two case-control studies in 955 Chinese and 750 Japanese patients.

Methods

We genotyped the previously implicated SNPs rs585017 (in RHOB) and rs4720262 (in TXNDC3) in patients with primary symptomatic knee OA with radiographic confirmation and in matched control individuals, and analyzed their associations. We further conducted a meta-analysis of the study findings together with those of previously reported European studies using the DerSimonian-Laird procedure.

Results

A significant association of RHOB with knee OA was observed in male Chinese patients (P = 0.02). No significant associations were found for RHOB in any other comparisons in the East Asian populations. The association of TXNDC3 was replicated in Chinese female (P = 0.04) and Japanese (P = 0.03) patients, although none of these associations persisted after Bonferroni correction. Significant association (P = 0.02 for the allelic frequency) with nonsignificant heterogeneity was found in the East Asian replication study. No significant association was found in any comparison in the meta-analysis for all studies.

Conclusion

Our study replicates the association, previously reported in European Caucasians, of TXNDC3 with knee OA susceptibility in an East Asian population.     

In vivo imaging of immunotoxin treatment using Katushka-transfected A-431 cells in a murine xenograft tumour model

Purpose

Preclinical in vivo analyses of treatment responses are an important prerequisite to evaluate new therapeutics. Molecular in vivo imaging in the far red (FR)/near infra red (NIR) is a promising method, as it enables measurements at different time points in individual animals, thereby reducing the number of animals required, while increasing statistical significance. Here, we show the establishment of a method to monitor response to treatment using fluorescent cells, expressing the epidermal growth factor receptor (EGFR), a target already used in therapy.

Methods

We transfected A-431 tumour cells with the far red–emitting protein Katushka (Kat2), resulting in strong fluorescence allowing for the monitoring of tumour growth when implanted in BALB/c nu/nu mice with a CRi Maestro in vivo imager. We targeted A-431 cells with a previously reported immunotoxin (IT), consisting of the anti-EGFR antibody single-chain variable fragment (scFv) 425, fused to Pseudomonas aeruginosa Exotoxin A’ (ETA’). In addition, EGFR expression was verified using the 425(scFv) conjugated to a NIR dye BG-747 through a SNAP-tag linker.

Results

The results show the feasibility to evaluate response to treatment in vivo by FR imaging, while at the same location detecting EGFR expression. Treatment with 425(scFv)-ETA’ resulted in decelerated tumour growth, while not affecting the overall health of the animals. This is in contrast to treatment with Doxorubicin, which, although decreasing the tumour size, resulted in poor health.

Conclusions

We developed a novel method to non-invasively determine treatment responses by in vivo imaging of multiple parameters which showed the efficacy of 425(scFv)-ETA’.     

Double suicide genes driven by kinase domain insert containing receptor promoter selectively kill human lung cancer cells

Background

Although B cells are important as antigen presenting cells (APC) during the immune response, their role in DNA vaccination models is unknown.

Methods

In this study in vitro and in vivo experiments were performed to evaluate the ability of B cells to protect mice against Mycobacterium tuberculosis challenge.

Results

In vitro and in vivo studies showed that B cells efficiently present antigens after naked plasmid pcDNA3 encoding M. leprae 65-kDa heat shock protein (pcDNA3-Hsp65) internalization and protect B knock-out (BKO) mice against Mycobacterium tuberculosis infection. pcDNA3-Hsp65-transfected B cells adoptively transferred into BKO mice rescued the memory phenotypes and reduced the number of CFU compared to wild-type mice.

Conclusions

These data not only suggest that B cells play an important role in the induction of CD8 T cells but also that they improve bacterial clearance in DNA vaccine model.     

Anti-type II collagen antibodies are associated with early radiographic destruction in rheumatoid arthritis

Introduction

We have previously reported that high levels of antibodies specific for native human type II collagen (anti-CII) at the time of RA diagnosis were associated with concurrent but not later signs of inflammation. This was associated with CII/anti-CII immune complex (IC)-induced production of pro-inflammatory cytokines in vitro. In contrast, anti-cyclic citrullinated peptide antibodies (anti-CCP) were associated both with late inflammation and late radiological destruction in the same RA cohort. We therefore hypothesized that anti-CII are also associated with early erosions.

Methods

Two-hundred-and-fifty-six patients from an early RA cohort were included. Baseline levels of anti-CII, anti-CCP and anti-mutated citrullinated vimentin were analyzed with ELISA, and rheumatoid factor levels were determined by nephelometry. Radiographs of hands and feet at baseline, after one and after two years were quantified using the 32-joints Larsen erosion score.

Results

Levels of anti-CII were bimodally distributed in the RA cohort, with a small (3.1%, 8/256) group of very high outliers with a median level 87 times higher than the median for the healthy control group. Using a cut-off discriminating the outlier group that was associated with anti-CII IC-induced production of proinflammatory cytokines in vitro, baseline anti-CII antibodies were significantly (p = 0.0486) associated with increased radiographic damage at the time of diagnosis. Anti-CII-positive patient had also significantly increased HAQ score (p = 0.0303), CRP (p = 0.0026) and ESR (p = 0.0396) at the time of diagnosis but not during follow-up. The median age among anti-CII-positive subjects was 12 years higher than among the anti-CII-negative patients.

Conclusion

In contrary to anti-CCP, anti-CII-positive patients with RA have increased joint destruction and HAQ score at baseline. Anti-CII thus characterizes an early inflammatory/destructive phenotype, in contrast to the late appearance of an inflammatory/destructive phenotype in anti-CCP positive RA patients. The anti-CII phenotype might account for part of the elderly acute onset RA phenotype with rather good prognosis.     

Maternal diabetes induces congenital heart defects in mice by altering the expression of genes involved in cardiovascular development

Background

Congenital heart defects are frequently observed in infants of diabetic mothers, but the molecular basis of the defects remains obscure. Thus, the present study was performed to gain some insights into the molecular pathogenesis of maternal diabetes-induced congenital heart defects in mice.

Methods and results

We analyzed the morphological changes, the expression pattern of some genes, the proliferation index and apoptosis in developing heart of embryos at E13.5 from streptozotocin-induced diabetic mice. Morphological analysis has shown the persistent truncus arteriosus combined with a ventricular septal defect in embryos of diabetic mice. Several other defects including defective endocardial cushion (EC) and aberrant myofibrillogenesis have also been found. Cardiac neural crest defects in experimental embryos were analyzed and validated by the protein expression of NCAM and PGP 9.5. In addition, the protein expression of Bmp4, Msx1 and Pax3 involved in the development of cardiac neural crest was found to be reduced in the defective hearts. The mRNA expression of Bmp4, Msx1 and Pax3 was significantly down-regulated (p < 0.001) in the hearts of experimental embryos. Further, the proliferation index was significantly decreased (p < 0.05), whereas the apoptotic cells were significantly increased (p < 0.001) in the EC and the ventricular myocardium of the experimental embryos.

Conclusion

It is suggested that the down-regulation of genes involved in development of cardiac neural crest could contribute to the pathogenesis of maternal diabetes-induced congenital heart defects.     

Influence of oxygen tension on myocardial performance. Evaluation by tissue Doppler imaging

Background

Endothelial function in hypercholesterolemic rabbits is usually evaluated ex vivo on isolated aortic rings. In vivo evaluation requires invasive imaging procedures that cannot be repeated serially.

Aim

We evaluated a non-invasive ultrasound technique to assess early endothelial function in rabbits and compare data with ex vivo measurements.

Methods

Twenty-four rabbits (fed with a cholesterol diet (0.5%) for 2 to 8 weeks) were given progressive infusions of acetylcholine (0.05–0.5 μg/kg/min) and their endothelial function was assessed in vivo by transcutaneous vascular ultrasound of the abdominal aorta. Ex vivo endothelial function was evaluated on isolated aortic rings and compared to in vivo data.

Results

Significant endothelial dysfunction was demonstrated in hypercholesterolemic animals as early as 2 weeks after beginning the cholesterol diet (aortic cross-sectional area variation: -2.9% vs. +4% for controls, p < 0.05). Unexpectedly, response to acetylcholine at 8 weeks was more variable. Endothelial function improved in 5 rabbits while 2 rabbits regained a normal endothelial function. These data corroborated well with ex vivo results.

Conclusion

Endothelial function can be evaluated non-invasively in vivo by transcutaneous vascular ultrasound of the abdominal aorta in the rabbit and results correlate well with ex vivo data.     

Effects of PM10 in human peripheral blood monocytes and J774 macrophages

Background

Asthma is characterized by type 2 T-helper cell (Th2) inflammation, goblet cell hyperplasia, airway hyperreactivity, and airway fibrosis. Monocyte chemoattractant protein-1 (MCP-1 or CCL2) and its receptor, CCR2, have been shown to play important roles in the development of Th2 inflammation. CCR2-deficient mice have been found to have altered inflammatory and physiologic responses in some models of experimental allergic asthma, but the role of CCR2 in contributing to inflammation and airway hyperreactivity appears to vary considerably between models. Furthermore, MCP-1-deficient mice have not previously been studied in models of experimental allergic asthma.

Methods

To test whether MCP-1 and CCR2 are each required for the development of experimental allergic asthma, we applied an Aspergillus antigen-induced model of Th2 cytokine-driven allergic asthma associated with airway fibrosis to mice deficient in either MCP-1 or CCR2. Previous studies with live Aspergillus conidia instilled into the lung revealed that MCP-1 and CCR2 play a role in anti-fungal responses; in contrast, we used a non-viable Aspergillus antigen preparation known to induce a robust eosinophilic inflammatory response.

Results

We found that wild-type C57BL/6 mice developed eosinophilic airway inflammation, goblet cell hyperplasia, airway hyperreactivity, elevations in serum IgE, and airway fibrosis in response to airway challenge with Aspergillus antigen. Surprisingly, mice deficient in either MCP-1 or CCR2 had responses to Aspergillus antigen similar to those seen in wild-type mice, including production of Th2 cytokines.

Conclusion

We conclude that robust Th2-mediated lung pathology can occur even in the complete absence of MCP-1 or CCR2.