Characterization of the T-cell Repertoire after Autologous HSCT in Patients with Ankylosing Spondylitis.

Autologous hematopoietic stem cell transplantation (HSCT), a safer type of HSCT than allogeneic HSCT, is a promising therapy for patients with severe autoimmune diseases (ADs). Despite the long history of medical practice, structural changes in the adaptive immune system as a result of autologous HSCT in patients with various types of ADs remain poorly understood. In this study, we used high-throughput sequencing to investigate the structural changes in the peripheral blood T-cell repertoire in adult patients with ankylosing spondylitis (AS) during two years after autologous HSCT. The implementation of unique molecular identifiers allowed us to substantially reduce the impact of the biases occurring during the preparation of libraries, to carry out a comparative analysis of the various properties of the T-cell repertoire between different time points, and to track the dynamics of both distinct T-cell clonotypes and T-cell subpopulations. In the first year of the reconstitution, clonal diversity of the T-cell repertoire remained lower than the initial one in both patients. During the second year after HSCT, clonal diversity continued to increase and reached a normal value in one of the patients. The increase in the diversity was associated with the emergence of a large number of low-frequency clonotypes, which were not identified before HSCT. Efficiency of clonotypes detection after HSCT was dependent on their abundance in the initial repertoire. Almost all of the 100 most abundant clonotypes observed before HSCT were detected 2 years after transplantation and remained highly abundant irrespective of their CD4+ or CD8+ phenotype. A total of up to 25% of peripheral blood T cells 2 years after HSCT were represented by clonotypes from the initial repertoire.

Tracking T-cell immune reconstitution after TCRαß/CD19-depleted hematopoietic cells transplantation in children.

αßT-cell-depleted allogeneic hematopoietic cell transplantation holds promise for the safe and accessible therapy of both malignant and non-malignant blood disorders. Here we employed molecular barcoding normalized T-cell receptor (TCR) profiling to quantitatively track T-cell immune reconstitution after TCRαß-/CD19-depleted transplantation in children. We demonstrate that seemingly early reconstitution of αßT-cell counts 2 months after transplantation is based on only several hundred rapidly expanded clones originating from non-depleted graft cells. In further months, frequency of these hyperexpanded clones declines, and after 1 year the observed T-cell counts and TCRß diversity are mostly provided by the newly produced T cells. We also demonstrate that high TCRß diversity at day 60 observed for some of the patients is determined by recipient T cells and intrathymic progenitors that survived conditioning regimen. Our results indicate that further efforts on optimization of TCRαß-/CD19-depleted transplantation protocols should be directed toward providing more efficient T-cell defense in the first months after transplantation.

Association of ERAP1 Allelic Variants with Risk of Ankylosing Spondylitis.

Ankylosing spondylitis (AS) belongs to a group of autoimmune diseases affecting the axial skeleton. Beside thehla-b*27allele, several other human genes that control the variety processes of immune homeostasis are considered to be associated with AS manifestation in different human populations. Among strong associated non-MHC geneserap1 encodingthe endoplasmic reticulum aminopeptidase 1 isoform was recently identified by single nucleotide polymorphisms (SNPs) meta analysis. In our study we inspected the genetic association of five non-synonymous coding SNPs fromerap1 withAS in Caucasians. We implemented the SSP-PCR system for precise genotyping of 87hla-b*27positive AS patients and 77hla-b*27healthy donors from the Russian population. Considerable differences in allele's frequencies within patients vs control cohort were shown for 3 of 5 SNPs under investigation. Using the EM-algorhitm we reconstructed 3-marker haplotypes that distinguish with high probability two cohorts due to differences in the haplotypes frequencies. In such a way both the sensitive, CCT, haplotype and the protective, TTC, one were predicted. To verify the calculation we determined genuine frequencies of 5-marker haplotypes in AS cohort by haplotyping of individual cDNA samples using improved SSP-PCR primer set. We demonstrated that the frequencies ofin silicareconstucted haplotypes and the frequencies of experimentally detected haplotypes are in a good agreement. Frequency of the risk haplotype CCT (rs17482078/10050860/2287987) detected within AS cohort reaches 88%, as well as the frequency calculated by EM-algorhitm.

Individual characterization of stably expanded T cell clones in ankylosing spondylitis patients.

Ankylosing spondylitis (AS) is commonly characterized by clonal expansions of T cells. However, these clonal populations are poorly studied and their role in disease initiation and progression remains unclear. Here, we performed mass sequencing of TCR V beta libraries to search for the expanded T cell clones for two AS patients. A number of clones comprising more than 5% of the corresponding TCR V beta family were identified in both patients. For the first time, expanded clones were shown to be stably abundant in blood samples of AS patients for the prolonged period (1.5 and 2.5 years for two patients, correspondingly). These clones were individually characterized in respect to their differentiation status using fluorescent cell sorting with CD27, CD28, and CD45RA markers followed by quantitative identification of each clone within corresponding fraction using real time PCR analysis. Stable clones differed in phenotype and several were shown to belong to the proinflammatory CD27 - /CD28 - population. Their potentially cytotoxic status was confirmed by staining with perforin-specific antibodies. Search for the TCR V beta CRD3 sequences homologous to the identified clones revealed close matches with the previously reported T cell clones from AS and reactive arthritis patients, thus supporting their role in the disease and proposing consensus TCR V beta CDR3 motifs for AS. Interestingly, these motifs were also found to have homology with earlier reported virus-specific CDR3 variants, indicating that viral infections could play role in development of AS.