Rheumatoid Arthritis: Aamar S

Eshkar Sebban L, Ronen D, Levartovsky D, Elkayam O, Caspi D, Aamar S, Amital H, Rubinow A, Golan I, Naor D, Zick Y, Golan I. · Lautenberg Center for General and Tumor Immunology, Hebrew University-Hadassah Medical School, Jerusalem, Israel. · J Immunol. · Pubmed #17617615 links to  free full text

Abstract: The synovial fluid (SF) cells of rheumatoid arthritis (RA) patients express a specific CD44 variant designated CD44vRA. Using a cellular model of this autoimmune disease, we show in this study that the mammalian lectin, galectin-8 (gal-8), is a novel high-affinity ligand of CD44vRA. By affinity chromatography, flow cytometry, and surface plasmon resonance, we demonstrate that gal-8 interacts with a high affinity (K(d), 6 x 10(-9) M) with CD44vRA. We further demonstrate that SF cells from RA patients express and secrete gal-8, to a concentration of 25-65 nM, well within the concentration of gal-8 required to induce apoptosis of SF cells. We further show that not all gal-8 remains freely soluble in the SF and at least part forms triple complexes with CD44 and fibrinogen that can be detected, after fibrinogen immunoprecipitation, with Abs against fibrinogen, gal-8 and CD44. These triple complexes may therefore increase the inflammatory reaction by sequestering the soluble gal-8, thereby reducing its ability to induce apoptosis in the inflammatory cells. Our findings not only shed light on the receptor-ligand relationships between CD44 and gal-8, but also underline the biological significance of these interactions, which may affect the extent of the autoimmune inflammatory response in the SF of RA patients.

Berkun Y, Abou Atta I, Rubinow A, Orbach H, Levartovsky D, Aamar S, Arbel O, Dresner-Pollak R, Friedman G, Ben-Yehuda A. · Department of Pediatrics, Safra Children's Hospital, Sheba Medical Center, Tel-Hashomer, Israel. · J Rheumatol. · Pubmed #17611986 No free full text.

Abstract: OBJECTIVE: To investigate the distribution of the A2756G polymorphism of the methionine synthase reductase (MTR) gene in patients with rheumatoid arthritis (RA) treated with methotrexate (MTX) compared with a healthy control group; and to examine the relationships among the A2756G polymorphism, plasma total homocysteine (tHcy), serum folate and vitamin B12 levels, disease activity, and MTX toxicity in patients with RA. METHODS: A cross-sectional study was performed on 86 MTX-treated RA patients, consisting of a clinical interview and physical examination to determine disease activity and MTX-related adverse reactions. Genotype analysis of the MTR gene was performed. Fasting plasma tHcy, serum folate, and vitamin B12 levels were measured. Allele and genotype distributions were compared to a healthy control group. RESULTS: The frequency of the 2756GG genotype (16.3%) in the RA study group was higher than that expected in the general population (3.6%; p < 0.000001). This genotype was associated with MTX-induced accelerated rheumatoid nodulosis (MIARN). No association of disease activity variables or plasma homocysteine with MTR A2756G polymorphisms was observed. The MTR 2756GG genotype, low plasma vitamin B12 levels, and the presence of rheumatoid nodules predicted MIARN. No association of nodulosis with any other indicator of disease activity or medical treatment was found. CONCLUSION: In our population of MTX-treated RA patients the 2756GG genotype of the MTR gene was more common than expected and was associated with MIARN.

Golan I, Nedvetzki S, Golan I, Eshkar-Sebban L, Levartovsky D, Elkayam O, Caspi D, Aamar S, Amital H, Rubinow A, Naor D. · The Lautenberg Center for General and Tumor Immunology, Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel. · J Autoimmun. · Pubmed #17383158 No free full text.

Abstract: Selective targeting of cells engaged in pathological activities is a major challenge for medical research. We generated monoclonal antibodies (mAbs) that exclusively bind, at concentrations ranging from 2 to 100 microg/ml, to a modified CD44 variant (designated CD44vRA) expressed on synovial fluid cells from joints of rheumatoid arthritis (RA) patients. These mAbs cross-reacted with keratinocytes expressing wild type CD44vRA (CD44v3-v10) only at a relatively high concentration (200 microg/ml). Sequence analysis of CD44vRA cDNA revealed, in 33 out of 43 RA and psoriatic arthritis patients, an extra intron-derived trinucleotide, CAG, which allows translation of an extra alanine. This insertion imposes a configurational change on the cell surface CD44 of RA synovial fluid cells, creating an immunogenic epitope and potentiating the ability to produce disease-specific antibodies. Indeed, the anti-CD44vRA mAbs (designated F8:33) were able to induce apoptosis in synovial fluid cells from RA patients, but not in peripheral blood leukocytes from the same patients, in keratinocytes from normal donors or in synovial fluid cells from osteoarthritis patients. Furthermore, injection of anti-CD44vRA mAbs reduced joint inflammation in DBA/1 mice with collagen-induced arthritis. These findings show that anti-CD44vRA mAbs are both bioactive and RA-specific.

Delague V, Chouery E, Corbani S, Ghanem I, Aamar S, Fischer J, Levy-Lahad E, Urtizberea JA, Mégarbané A. · Unité de Génétique Médicale, Laboratoire de Biologie Moléculaire et Cytogénétique, Faculté de Médecine, Université Saint-Joseph, Beirut, Lebanon. · Am J Med Genet A. · Pubmed #16152649 No free full text.

Abstract: Progressive pseudorheumatoid dysplasia (PPD) is a rare autosomal recessive syndrome characterized by the presence of spondyloepiphyseal dysplasia associated with pain, stiffness, and swelling of multiple joints, osteoporosis, and the absence of destructive bone changes. The disorder is caused by mutations of the WISP3 gene located on chromosome 6q22. We hereby report the molecular study of the WISP3 gene in nine unrelated consanguineous families originating from the Middle-East: three from Lebanon, five from Syria, and one from Palestinian Bedouin descent, all affected with PPD. Five different sequence variations were identified in the WISP3 gene, two of them being new mutations: the c.589G --> C transversion at codon 197, responsible for a splicing defect (A197fsX201); and the c.536_537delGT deletion (C179fsX), both in exon 3. In all other families, the affected patients were homozygous for a previously described nonsense mutation, namely c.156C --> A (C52X). Interestingly, in the latter families, the C52X mutation was always found associated with a novel c.248G --> A (G83E) variation, suggesting the existence of a founder effect.

Berkun Y, Levartovsky D, Rubinow A, Orbach H, Aamar S, Grenader T, Abou Atta I, Mevorach D, Friedman G, Ben-Yehuda A. · Department of Paediatrics, Bikur Cholim General Hospital, POB 492, Jerusalem 91004, Israel. · Ann Rheum Dis. · Pubmed #15361376 links to  free full text

Abstract: BACKGROUND: There is an association between C677T polymorphism of the methylenetetrahydrofolate reductase (MTHFR) gene and methotrexate related toxicity. OBJECTIVE: To examine the relations between the recently described A1298C polymorphism of the MTHFR gene, plasma homocysteine, methotrexate toxicity, and disease activity in patients with rheumatoid arthritis. DESIGN: A cross sectional study on 93 methotrexate treated patients with rheumatoid arthritis, comprising a clinical interview and physical examination to determine disease activity and methotrexate related adverse reactions. Genotype analysis of the MTHFR gene was carried out and fasting plasma homocysteine and serum folate concentrations were measured. The data were analysed using univariate analysis. Allele and genotype distributions were compared with those of a healthy control group. RESULTS: The frequency of the 1298CC genotype (24.7%) in the rheumatoid study group was greater than expected in the general population (12.8%, p<0.001). This genotype was associated with a significantly low rate of methotrexate related side effects. The odds ratio for side effects in patients with wild type 1298AA genotype v 1298CC genotype was 5.24 (95% confidence interval, 1.38 to 20). No correlation of disease activity variables or plasma homocysteine with MTHFR A1298C and C677T polymorphisms was observed. CONCLUSIONS: 1298CC polymorphism was more common in methotrexate treated rheumatoid patients than expected in the population, and was associated with a reduction in methotrexate related adverse effects. The A1298C polymorphism of the MTHFR gene may indicate a need to adjust the dose of methotrexate given to patients with rheumatoid arthritis.

Amital H, Aamar S, Rubinow A. · Rheumatology Unit, Division of Internal Medicine, Hadassah-Hebrew University School of Medicine, Jerusalem, Israel. · J Bone Joint Surg Am. · Pubmed #14630854 No free full text.

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