Wnt signaling is involved in human articular chondrocyte de-differentiation in vitro

Osteoarthritis is the most prevalent form of arthritis in the world. Certain signaling pathways, such as the wnt pathway, are involved in cartilage pathology. Osteoarthritic chondrocytes undergo morphological and biochemical changes that lead to chondrocyte de-differentiation. We investigated whether the Wnt pathway is involved in de-differentiation of human articular chondrocytes in vitro. Human articular chondrocytes were cultured for four passages in the presence or absence of IL-1 in monolayer or micromass culture. Changes in cell morphology were monitored by light microscopy. Protein and gene expression of chondrocyte markers and Wnt pathway components were determined by Western blotting and qPCR after culture. After culturing for four passages, chondrocytes exhibited a fibroblast-like morphology. Collagen type II and aggrecan protein and gene expression decreased, while collagen type I, matrix metalloproteinase 13, and nitric oxide synthase expressions increased. Wnt molecule expression profiles changed; Wnt5a protein expression, the Wnt target gene, c-jun, and in Wnt pathway regulator, sFRP4 increased. Treatment with IL-1 caused chondrocyte morphology to become more filament-like. This change in morphology was accompanied by extinction of col II expression and increased col I, MMP13 and eNOS expression. Changes in expression of the Wnt pathway components also were observed. Wnt7a decreased significantly, while Wnt5a, LRP5, β-catenin and c-jun expressions increased. Culture of human articular chondrocytes with or without IL-1 not only induced chondrocyte de-differentiation, but also changed the expression profiles of Wnt components, which suggests that the Wnt pathway is involved in chondrocyte de-differentiation in vitro.

The roles of canonical and non-canonical Wnt signaling in human de-differentiated articular chondrocytes

Osteoarthritis is the most prevalent form of arthritis in the world and it is becoming a major public health problem. Osteoarthritic chondrocytes undergo morphological and biochemical changes that lead to de-differentiation. The involvement of signaling pathways, such as the Wnt pathway, during cartilage pathology has been reported. Wnt signaling regulates critical biological processes. Wnt signals are transduced through at least three intracellular signaling pathways including the canonical Wnt/β-catenin pathway, the Wnt/Ca2 + pathway and the Wnt/planar cell polarity pathway. We investigated the involvement of the Wnt canonical and non-canonical pathways in human articular chondrocyte de-differentiation in vitro. Human articular chondrocytes were cultured through four passages with no treatment, or with sFRP3 treatment, an inhibitor of Wnt pathways, or with DKK1 treatment, an inhibitor of the canonical pathway. Chondrocyte-secreted markers and Wnt pathway components were analyzed using western blotting and qPCR. Inhibition of the Wnt pathway showed that the canonical Wnt signaling probably is responsible for inhibition of collagen II expression, activation of metalloproteinase 13 expression and regulation of Wnt7a and c-jun expression during chondrocyte de-differentiation in vitro. Our results also suggest that expressions of eNOS, Wnt5a and cyclinE1 are regulated by non-canonical Wnt signaling.

Circulating antimyenteric autoantibodies in Tunisian patients with idiopathic achalasia

The physiopathology of idiopathic achalasia is still unknown. The description of circulating antimyenteric autoantibodies (CAA), directed against enteric neurons in sera of patients, suggests an autoimmune process. Recent data showed controversies according to the existence and the significance of CAA. The aims of this study were to investigate whether CAA are detected in Tunisian patients with idiopathic achalasia and to look for associated clinical or manometrical factors with CAA positivity. Twenty-seven patients with idiopathic achalasia and 57 healthy controls were prospectively studied. CAA were assessed by indirect immunofluorescence on intestinal monkey tissue sections. Western blot on primate cerebellum protein extract and dot technique with highly purified recombinant neuronal antigens (Hu, Ri, and Yo) were further used to analyze target antigens of CAA. CAA were significantly increased in achalasia patients compared with controls when considering nuclear or cytoplasmic fluorescence patterns. (33% vs. 12%, P = 0.03 and 48% vs. 23%, P = 0.001 respectively). By immunoblot analysis, CAA did not target neuronal antigens, however 52/53 and 49 kDa bands were consistently detected. CAA positivity was not correlated to specific clinical features. The results are along with previous studies demonstrating high CAA prevalence in achalasia patients. When reviewing technical protocols and interpretation criteria, several discrepancies which could explain controversies between studies were noted.

[Clinical, radiographic and biologic particularities of ankylosing spondylitis in Tunisian patients according to the presence or the absence of the HLA B27 and its sub-types]

To assess the clinical, radiographic and biologic particularities of ankylosing spondylitis (AS) in Tunisian patients according to HLA B27 and its sub-types statute. This was a case-control study that included 100 patients (85 males/15 females) with AS according to the modified New York criteria. Demographic, clinical, AS specific indexes, radiographic and biologic parameters were determined. HLA-B and B27 subtypes typing of all subjects were performed by PCR-SSP. Patients mean age was 38.4 years +/- 12.6 HLA-B27 was found in 62% of patients. The comparison of B27 positive and B27 negative patients revealed a correlation of B27 with age, male gender, family history of spondylarthropathies, age at disease onset, acute onset of the disease, inaugural spinal involvement, uveitis, bilateral and destructive hip arthritis as well as a high score of mSASSS. The most frequent sub-types of HLA B27 were B*2702 (49.2%) and B*2705 (36.3%). No significant difference of the clinical presentation of the disease or severity factors was found among these patients. This study confirmed the contribution of the HLA B27 to the determination of the clinical presentation of AS. The variability of factors linked to B27 may be explained by the polygenic model of the disease.

Expression patterns of Notch receptors and their ligands in human osteoarthritic and healthy articular cartilage

Notch pathway plays a pivotal role in cell fate determination. There is much interest surrounding its therapeutic potential, in osteoarthritis, but the expression profile of Notch-related molecules, as well as their relation with cartilage pathological parameters, remains unclear. The purpose of our study is to analyze the expression pattern of Notch family members, type II and type I collagen, in normal (healthy) and osteoarthritic human knee cartilage. Osteoarthritic cartilages were obtained from 3 patients undergoing a total knee replacement. Macroscopically normal cartilage was dissected from 3 human knees at the time of autopsy or surgery. Immunohistochemical staining was performed using Notch1,2,3 and 4, Delta, Jagged, type II collagen and type I collagen antibodies. In healthy cartilage, type II collagen was abundantly expressed while type I was absent. This latter increased proportionally to the osteoarthritic grade. Type II collagen expression remained intense in osteoarthritic cartilage. In healthy cartilage as well as in cartilage with minor lesions, Notch family member's proteins were not or just weakly expressed at the surface and in the cells. However, Notch molecules were over-expressed in osteoarthritic cartilage compared to healthy one. This expression pattern was different according to the cartilage zone and the severity of OA. Our data suggest that Notch signaling is activated in osteoarthritic cartilage, compared to healthy cartilage, with a much more abundant expression in the most damaged areas.

Spectrum of autoantibodies other than anti-desmoglein in pemphigus patients

BACKGROUND

Pemphigus is a life-threatening autoimmune blistering disease mediated by autoantibodies against adhesion molecule of the skin. Its concurrence with systemic and organ-specific autoimmune disease was described in case reports.

OBJECTIVES

To evaluate the presence of a broad spectrum of organ-specific and non-organ-specific autoantibodies other than anti-desmoglein antibodies in pemphigus patients.

PATIENTS AND METHODS

Serum samples were obtained from 105 pemphigus foliaceus (PF) patients, 51 pemphigus vulgaris (PV) patients and 50 controls. Both indirect immunofluorescence assay and ELISA were used to assess the presence of autoantibodies related to connective tissue diseases, autoimmune hepatitis, vasculitis, rheumatoid arthritis, coeliac disease, diabetes and thyroiditis.

RESULTS

Significant difference was observed between the three groups for anti-thyroglobulin antibodies in the pemphigus foliaceus group (18% vs. 4%, P=0.03). A significantly higher occurrence of IgM anti-cardiolipin (P=0.03), IgG anti-reticulin (P=0.01) and IgG anti-gliadin antibodies (P=0.008) were observed in the PV group. Cases with more than four autoantibodies were frequently positives for both anti-desmoglein 1 and anti-desmoglein 3.

CONCLUSION

Autoantibodies other than anti-desmoglein antibodies are not rare in pemphigus patients. Clinical and serological follow-up of pemphigus patients with positive autoantibodies are needed to clarify their impact in disease evolution.

Expression of Notch family members in cultured murine articular chondrocytes

The Notch family is involved in cell differentiation during embryogenesis. Osteoarthritic chondrocytes undergo morphological and biochemical changes leading to the de-differentiation process. In the study reported here, we were interested in the involvement of the Notch pathway in murine articular chondrocyte de-differentiation. Articular chondrocytes were subjected to several cell culture passages and treated with or without a Notch inhibitor, N-[N-(3, 5-difluorophenacetyl-L-alanyl)]-S-phenylglycine t-Butyl Ester (DAPT). Chondrocyte morphology was studied using optical microscopy. Immunocytochemistry and immunoblot were performed to study the expression of collagens and Notch family members. Without DAPT treatment, chondrocyte de-differentiation resulted in fibroblast-like morphology. This was confirmed by immunocytochemical staining and immunoblot analysis, which showed an increase in collagen type I (col I) and a decrease in collagen type II (col II) expression. With DAPT treatment, de-differentiation was delayed. Immunocytochemistry and immunoblot analysis showed during the first passages inhibition of col II expression, which then was re-instituted during the last passage, suggesting chondrocyte re-differentiation. In the study reported here, we showed that inhibition of the Notch receptor not only delayed the de-differentiation process, but also chondrocyte re-differentiation, which confirms the involvement of the Notch pathway in chondrocyte de-differentiation.

Ketosis-onset diabetes in Tunisian adults: immunological markers and beta-cell function

The aim of this study in Tunisia was to classify ketosis-onset diabetes in adult patients. All patients aged > 30 years without known diabetes, presenting with ketosis and admitted to our department were studied. Patients with secondary or gestational diabetes and those on corticoid therapy or with coinciding infection were excluded. The data included clinical characteristics, immunological markers and beta-cell function. Of the 63 patients, islet-cell antibodies were present in 27.0%, glutamic acid decarboxylase antibodies in 25.4% and thyrosin phosphatase antibodies in 19.0%. Beta-cell functional reserve was preserved in 54.0%. Our results confirm that patients with ketosis-onset diabetes mellitus in adulthood are a heterogeneous group.

[Recurrent rhinitis and pulmonary infections revealing celiac disease: case report]

Celiac disease is associated with a number of extra-gastrointestinal features such as hepatitis, arthralgia, and recurrent foetal loss. However respiratory involvement is an extremely rare disorder. We report a case of celiac disease revealed by bronchiectasia in a 39-year-old man. The patient reported a history of recurrent pulmonary infections and intermittent intestinal symptoms in childhood. Wegner granulomatosis was initially suspected because of rhinopulmonary involvement. Serum's patient was tested for ANCA and anti-tissue antibodies. The latest test was performed on histological sections from rat and revealed the presence of anti-reticulin antibodies. Further testing, for anti-tissue transglutaminase and anti-endomysium antibodies, revealed positive results. Celiac disease was confirmed by histological examination of intestinal biopsy. Pulmonary symptoms were improved on a gluten free diet suggesting a causal relationship between celiac disease and respiratory symptoms.

[Prevalence of diabetes-related autoantibodies in celiac disease]

THE AIM

of this study is to investigate the prevalence of diabetes-related autoantibodies in a group of children with celiac disease and to compare it with a control group.

MATERIAL AND METHODS

We recruited 31 celiac children at diagnosis (on gluten containing diet) and 31 age and sex matched healthy children. Anti-islet cell antibodies (ICA) were detected by indirect immunofluorescence on monkey pancreas. Anti-glutamate decarboxylase (anti-GAD) and anti-tyrosine phosphatase (anti-IA2) antibodies were assessed by a radio-immuno- precipitation method.

RESULTS

Three out of 31 celiac patients (9.7%) had one or more diabetes-related autoantibodies. ICA, anti-GAD and anti-IA2 were found in respectively 3.2%; 3.2% and 9.7% of patients. Only one control (3.2%) had anti-GAD. There was no statistically significant difference between the 2 groups.

CONCLUSION

The risk to develop diabetes seems to be the same in celiac patients and in healthy subjects thus screening of diabetes-related autoantibodies is not justified in celiac patients.

Physiopathologie de l'arthrose. Du cartilage normal au cartilage arthrosique: facteurs de prédisposition et mécanismes inflammatoires

INTRODUCTION

osteoarthritis is the most prevalent form of arthritis in the world. With the progressive ageing of the population, it becomes a major problem of public health. Osteoarthritis is a degenerative affection characterized by many disorders leading to a structural and functional defect of one or several joints.

CURRENT KNOWLEDGE AND KEY POINTS

In this review, we focus on the main inflammatory mechanisms occurring in cartilage during primary osteoarthritis. We also describe some well established risk factors involved in the pathogenesis of this disease such as age, overload and genetic factors. Indeed, osteoarthritis is the result of an imbalance between the processes of degradation and the attempts of repair by the chondrocyte which is the exclusive cell type in cartilage. Degradation is induced by several chemical substances such as proteolytic enzymes (metalloproteinases) and pro-inflammatory cytokines especially interleukin 1beta. To face these events, the chondrocyte starts attempts of repair by secreting growth factors (Transforming Growth Factor and Insulin Growth Factor) or anti-inflammatory cytokines (interleukins 4 and 10) unsuccessfully. All these events will lead to the structural modifications observed in the osteoarthritic cartilage.

PROSPECTS

A better comprehension of the physiopathology of osteoarthritis will allow an improvement of therapeutic strategies of this common and invalidating disease.

[Susceptibility markers in Tunisian first-degree relatives of patients with type 1 diabetes]

To identify the profile of anti-pancreas autoantibodies and elucidate the HLA DRB1, DQB1 polymorphism in Tunisian first-degree relatives of patients with type 1 diabetes, we recruited 96 relatives from 21 families with at least one diabetic child. Islet cell antibodies (ICA) were detected by immunofluorescence on monkey pancreas; glutamate decarboxylase (GADA), IA2 (IA2-A) and insulin (IAA) antibodies were measured by RIA. HLA class II DRB1 and DQB1 alleles were typed by PCR-SSP. ICA, GADA, IA2-A and IAA were found in respectively 11.5, 4.2, 5.2 and 8.3% of relatives. Twenty-two out of 96 had at least one antibody and 20 out of these 22 had a susceptibility allele (DRB1*03, DRB1*04, DQB1*02 or DQB1*0302) with or without protective allele (DRB1*11, DRB1*13, DRB1*15 or DQB1*06). All of the 5 relatives having 2 autoantibodies or more carried the DRB1*04-DQB1*0302 susceptible haplotype. In conclusion, this observational study confirms in a Tunisian population known epidemiological data and demonstrates the usefulness of follow-up to determine the predictive value of studied markers.

[Prevalence of celiac disease serological markers in Tunisian type 1 diabetic adults]

OBJECTIVE

to evaluate the prevalence of celiac serological markers; anti-transglutaminase (ATGt), anti-endomysium (AE), anti-gliadin (AGD) and anti-reticulin (AR) antibodies; in type 1 diabetic Tunisian adults.

SUBJECTS AND METHODS

261 type 1 diabetic patients aged from 16 to 60 years were enrolled in this prospective study. IgG and IgA transglutaminase and gliadin were measured with ELISA. IgA AE were tested by indirect immunofluorescence using 2 substrates; monkey oesophagus and human umbilical cord. AR were detected by indirect immunofluorescence on rat liver, kidney and stomach. Sera IgA level was measured by turbidimetry.

RESULTS

83/261 of diabetics were positive for at least one antibody, 5.7% had ATGt-A, 3.4% AE on monkey esophagus, 3.1% AE on umbilical cordon, 18% AGD-A, 19.5% AGD-G and 3.1% AR. There was an excellent concordance between AE and ATGt (r = 0.9). Out of the 261 diabetics, 5 had an IgA deficiency and one of them has IgG AE and ATGt.

CONCLUSION

serological markers of celiac disease seem to be frequent in diabetics. Nevertheless, diagnosis must be confirmed by histological studies which allow us to know the real prevalence of celiac disease in diabetic adults.

[Complement protein hereditary deficits during purulent meningitis: study of 61 adult Tunisian patients]

Sixty one Tunisian adult patients with bacterial meningitis were screened for complement deficiency. Functional activity of the classical and the alternative pathways of complement (CH50 and AP50 respectively) were measured according to standard haemolytic procedures. Serum concentrations of C3 and C4 were determined by nephelometry. Late complement component (C5-C9) and properdin concentrations were assessed by double-ligand EISA. Complement deficiency was found in eight patients (13%): Seven had late complement component deficiency (three C7 deficiency, two C5 deficiency, one C6 deficiency and one C8 deficiency) and one had partial properdin deficiency. Patients with late complement component deficiency had a mean age of 24 years (range 17-32 years). All deficient patients had meningococcal meningitis. Recurrent meningitis was reported in half of the patients. Our findings demonstrated a high prevalence of complement deficiency in Tunisia suggesting that screening for hereditary complement deficiency should be performed in case of bacterial meningitides and meningococcal disease patients.

Celiac disease in adult patients with type 1 diabetes mellitus in Tunisia

OBJECTIVE

Type1 diabetes mellitus may be associated with celiac disease. The prevalence of celiac disease as determined by screening among adult patients with type 1 diabetes is high with rates of 1.07.8% in Europe and U.S.A. The aims of the study are to determine the prevalence of celiac disease in adults with type 1 diabetes in Tunisia.

METHODS

348 consecutive adult patients with type1 diabetes were investigated prospectively and screened for celiac disease. The mean age was 28.45+/-10.74 years old. There were 176 females and 172 males. For the screening of celiac disease, we used immunoglobulin A (IgA) anti-endomysium (EMA) antibodies determined by an indirect immunofluorescence method. Anti-transglutaminase (tTG) antibodies were determined by an ELISA method. Those patients with positive results for anti EMA and or tTG were proposed for duodenal biopsy.

RESULTS

14 patients were positive for anti EMA and had high or a weak positive level of tTG antibodies. One patient from this group was already known to have celiac disease. Only 8 patients consented to biopsy and morphological changes were consistent with celiac disease in all cases. Prevalence of biopsy-proven celiac disease was 2.3% (95% CI=1.0-4.5%).

CONCLUSION

The present study confirms that celiac disease of adults is prevalent in type 1 diabetic patients in Tunisia. Serological screening for celiac disease in type 1 diabetes is important because many patients are asymptomatic and most are detected by the screening.

[Determination of anti-transglutaminase antibodies in the diagnosis of coeliac disease in children: results of a five year prospective study]

AIM

To evaluate the interest of IgA antibodies to tissue transglutaminase in the diagnosis of children coeliac disease compared with anti-endomysium and anti-gliadin antibodies.

SUBJECTS AND METHODS

Seventy children with coeliac disease (mean age: 5 years and 8 months) and 99 disease controls (mean age: 4 years and 5 months). IgA anti-transglutaminase were tested by ELISA using a human recombinant tissue transglutaminase. IgA anti-endomysium were detected by indirect immunofluorescence on monkey oesophagus.

RESULTS

The middle rate of IgA anti-transglutaminase was 101.06 units in patients and only 0.47 unit in controls. IgA anti-transglutaminase and IgA anti-endomysium were in agreement in 98.8% of cases; only two cases were discordant (+/- and -/+). Globally, the two markers had the same sensitivity (90%), specificity (98%), negative (93.2%) and positive (96.9%) predictive values. For anti-gliadin antibodies, the IgG were more sensitive (88.6%) and the IgA more specific (93.9%).

CONCLUSION

IgA anti-tissue transglutaminase can be used instead of IgA anti-endomysium as a serological marker of screening and diagnosis of coeliac disease in children after 3 years.

[Antiphosphoplipid antibodies and retinal occlusive vasculopathy]

PURPOSE

to determine the prevalence of antiphospholipid antibodies in patients with occlusive retinal vascular events, exempt from conventional risk factors of retinal thrombosis.

METHODS

eleven patients with retinal vascular occlusion, free of main accepted risk factors for retinal thrombosis, were retrospectively screened for antiphospholipid antibodies (anticardiolipin and anti-beta2 glycoprotein 1 antibodies) by an Elisa method. Prevalence of antiphospholipid antibodies were compared with those in a homogenous control group of 100 patients.

RESULTS

the prevalence of antiphospholipid antibodies in the study group was 27% (three of 11). Comparison with control group prevalence (3%) showed a statistically significant difference (p < 0,001). One patient in the study disclosed positivity for IgG anticardiolipine antibodies, one for IgM anticardiolipine antibodies and one for anti-beta2 glycoprotein 1 antibodies.

CONCLUSION

our results lead us to recommend a systematic search for specific antiphospholipid antibodies in such young patients which could have an importance for the diagnosis of primary antiphospholipid syndrome.

[Tuberculosis, primary biliary cirrhosis and autoimmunity (apropos of a case in Tunisia)]

We report the case of a 70 year-old Tunisian patient who developed antimitochondrial antibodies and anti-ADN during urogenital tuberculosis with clinical and biological signs of primary biliary cirrhosis and systemic lupus erythematosus. We discuss the association of the three diseases and the etiopathogeny of the autoimmune mechanisms induced by Mycobacterium tuberculosis.