BAFF from bone marrow-derived mesenchymal stromal cells of rheumatoid arthritis patients improves their B-cell viability-supporting properties.

Mesenchymal stromal cells (MSCs) represent a unique cell type with anti-proliferative effects on activated T and B cells. Based on our observation of differences between rheumatoid arthritis and osteoarthritis bone marrow B cells we hypothesized that rheumatoid arthritis bone marrow MSCs may enhance B-cell survival. We aimed to compare the effect of rheumatoid arthritis and osteoarthritis bone marrow-derived MSCs (rheumatoid arthritis MSCs, osteoarthritis MSCs) on the survival of healthy donor purified B cells. Rheumatoid arthritis and osteoarthritis MSCs were isolated from patients undergoing hip replacement surgery, and cultured in vitro for 2-5 passages. Washed cells were co-cultured with CD20+ B cells for 30-90 hours. Cell survival was analysed using 7-amino-actinomycin D labelling by flow cytometry. Expression of mRNA and protein was determined by RT-PCR and flow cytomery. Co-culture with both rheumatoid arthritis MSCs and osteoarthritis MSCs significantly enhanced B-cell survival, the effect being more prominent in rheumatoid arthritis MSCs. Both types of MSCs displayed expression of B cell-activating factor mRNA and protein. Blocking B cell-activating factor signalling from MSCs by specific anti-B cell-activating factor and anti-B cell-activating factor receptor antibodies weakly reversed the effect of MSCs on B-cell survival mainly in rheumatoid arthritis MSCs. MSC interaction with B cells provides stimuli for B-cell survival and therefore may contribute to the pathogenesis of rheumatoid arthritis. MSC-derived factors other than B cell-activating factor are likely to contribute to this effect. This feature is more prominent in rheumatoid arthritis MSCs, possibly due to the B cell-activating factor.

B cell activating factor, its role in autoimmunity, and targeting in autoimmune diseases.

B cell activation factor (BAFF), a recently identified member of the tumour necrosis factor (TNF) family, is a key survival factor during B cell maturation and is essential for the development of B cell tolerance. Breakdown of the regulation of BAFF expression results in excessive BAFF production that impairs B cell tolerance and leads to autoimmune phenomena. Consistent with this, BAFF levels are elevated in plasma of patients with various autoimmune diseases. BAFF is considered to be one of the principal factors that regulate the size and composition of B cell compartment. BAFF acts as an important driving factor for B cell hyperplasia and autoantibody production in autoimmune processes. Thus BAFF has become a very attractive target for the treatment of autoimmune diseases with an altered B cell function. Results of clinical trials have confirmed a crucial role of BAFF in the pathogenesis of rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). BAFF inhibitors in the treatment of RA, SLE and other autoimmune diseases are under intensive investigation. However, BAFF biology remains poorly understood. Nonetheless, results of the ongoing studies may enable the development of a new generation of BAFF inhibitors with more selective efficacy and increased safety (Fig. 2, Ref. 92). Full Text (Free, PDF) www.bmj.sk.

Establishing the method of chimerism monitoring after allogeneic stem cell transplantation using multiplex polymerase chain reaction amplification of short tandem repeat markers and Amelogenin.

We describe the implementation, optimization, sensitivity determination and first clinical results of polymerase chain reaction (PCR) amplification of polymorphic short tandem repeat (STR) markers and Amelogenin locus coupled with fluorescent detection and capillary electrophoresis in chimerism monitoring of patients transplanted at three different transplant centers using a commercially available multiplex microsatellite assay. The chimerism analysis was performed with genomic DNA extracted from unselected peripheral blood leukocytes of one hundred pediatric and adult patients, who underwent allogeneic stem cell transplantation (SCT) from human leukocyte antigen (HLA) matched or one antigen mismatched related or unrelated donors for malignant (70 patients) and non-malignant (30 patients) diseases. Tested were 79 donor recipient pairs for 15 STR systems and identified an informative marker in all but one of them (98,7%), using 6 selected systems out of these fifteen, that appeared highly informative in our patients population. In 21 sex-mismatched donor recipient pairs we used the Amelogenin locus to distinguish the X and Y chromosome. In sixty-three out of these 100 patients chimerism was regularly analyzed from blood samples taken at various time points after SCT with the median follow up of 17 months. Complete chimerism (CC), maintained over the whole follow-up period, was detected in 24 (38, 1%), stable and decreasing mixed chimerism (MC) in 28 (44, 4%) and increasing MC in 11 patients (17, 5%). Patients with CC, stable and decreasing MC showed a significantly better (p 0,005) overall survival rate (0, 81), compared to those with increasing MC (0, 24). These results demonstrate that STR-based chimerism monitoring with sensitivity above 1% and high informativity (98, 7% of donor recipient pairs) is necessary in establishing the origin of engrafted cells after an allogeneic SCT, in detecting graft rejection and that it may contribute in identifying patients with imminent leukemia relapse.

Associations between HLA class II alleles and type 1 diabetes mellitus in the Slovak population.

OBJECTIVES: Several associations between HLA complex and diabetes mellitus type IA were found in various groups of patients of Caucasoid population. This study was therefore prompted to be conducted in Slovak population, since any such has not yet been performed in Slovak population. METHODS: Patients suffering from DM-1A originated from all regions of Slovakia. Their age ranged from 1 to 42 years; but the criterion for including the subject to the study was the definition of diagnosis in older patients before their age of 15 (Table 1). The diagnosis was set up according to internationally accepted criteria. A total of 460 patients was typed for HLA-DQB1 alleles, among them 97 also for HLA-DQA1 and 146 for HLA-DRB1 alleles. HLA-typing was performed by a PCR-SSP method. Control group consisted of 196 (DQA), 143 (DQB1) and 130 (DRB1) unrelated blood donors aged 19-55 years old irrespective of their age or sex. The data obtained were expressed in a 2 x 2 contingency table and statistical significance was calculated by the Fisher exact test. RESULTS: Among 11 HLA-DQB1 alleles tested DOB1*0302 was the most frequent in DM-1A patients (30.33% vs. 5.59% in healthy subjects (HS), followed by DQB1*0201 (22.93% vs. 12.94%, respectively). In contrast, the frequency rate of DQB1*0301 (10.66% vs. 24.48%), DOB1*0602 (2.17% vs. 10.14%) and DQB1*0603 (2.5% vs. 8.39 %) were decreased in DM-1A patients. Out of 14 DQA1 alleles the highest occurrence rate showed DQA1*0301 (30.93% vs. 17.09) and DQA1*0501 (34.02% vs. 25.76%), while DQA1*0102 (8.76% vs. 16.58%) and DQA1*0201 (6.18 % vs. 13.51%7), respectively, were found to be the least frequent. Among 13 HLA-DRB1 alleles tested, the most common occurrence rates showed DRB1*03 (26.37% vs. 9.62%) and DRB1*04 (7.19% vs. 14.23%), while the least frequent alleles were DRB 1*15 (2.74% vs. 12.31%), DRB1*07 (7.19% vs. 14.23%), and DRB1*11 (2.74% vs. 20.38%). The alleles DQB1*0302 and DQA1*0301, respectively, were present in the same individual in all DRB1*04 positive patients, suggesting that they belong to the haplotype. Similar situation was observed with the alleles DQB1*0201, DQA1*0501, and DRB*0301, respectively, forming the second HLA haplotype so characteristic for DM1A.