-Regulatory T Cells in Human Allergic Asthma

Abstracts developed in order to expand these cells for use as a viable therapeutic agent in the treatment of autoimmune disease. doi:10.1016/j.clim.2009.03.011

OR.5. The Naturally Occurring Splice Variant of FOXP3 Lacking Exon 2 is not Sufficient to Maintain Immune Homeostasis and Prevent IPEX in vivo in Humans Stephanie Anover-Sombke 1, Mary Hackett 1, Hans Ochs 1, Eleonora Gambineri 2, Troy Torgerson1. 1University of Washington and Seattle Children's, Seattle, WA; 2bA. MeyerQ Children's Hospital and University of Florence, Florence, Italy The Immune dysregulation, Polyendocrinopathy, Enteropathy, X-linked (IPEX) syndrome is a clinical disorder characterized by systemic autoimmunity affecting the gastrointestinal tract, pancreas, thyroid, skin and other organs. It is caused by mutations in the FOXP3 gene which encodes a transcriptional regulator that is critical for the development and function of naturally arising CD4+CD25+regulatory T cells (Treg). Under normal conditions, the FOXP3 gene encodes two predominant isoforms of the FOXP3 protein that arise from mRNA splice variants that differ only in the presence or absence of exon 2. The segment of the protein encoded by exon 2 is functionally critical for the transcriptional repression exerted by FOXP3 and has also been shown to be involved in binding to other critical transcriptional regulators such as RORγT. Multiple studies demonstrate that the full length protein is capable of supporting Treg development and function but there are confliciting reports about whether the shorter isoform is capable of the same. In a large cohort of patients with symptoms of IPEX, we have now identified 3 unrelated male patients with symptoms of IPEX that have mutations which are predicted to allow expression of only the short isoform of FOXP3. Two of the three patients have a somewhat milder phenotype but nonetheless have all of the features of IPEX syndrome suggesting that in vivo, the short isoform of FOXP3 is unable to fully sustain Treg development and function. doi:10.1016/j.clim.2009.03.012

OR.6. Selective Deregulation in Chemokine Signaling Pathways of CD4+CD25hiCD127lo/-Regulatory T Cells in Human Allergic Asthma Khoa Nguyen, Kari Nadeau. Stanford University, Stanford, CA Objective: CD4+CD25hiCD127lo/-regulatory T cells have been suggested to be critical regulators of inflammatory processes in allergic asthma. Recent studies reported a selective decrease in the frequency of regulatory T cells in the bronchoalveolar lavage fluid of allergic asthmatic (AA) subjects, prompting the possibility of defective recruitment of these cells to the airway in response to chemokines produced during asthmatic inflammation. This study aimed to characterize the chemotactic profile of circulating regulatory T cells in AA

S7 subjects in response to chemokines abundantly produced in airway inflammation, such as CCL1, CCL17, and CCL22. Methods: The study was performed in a cohort of 26 AA, 16 healthy control, and 16 non-AA subjects. We used chemotaxis assays to evaluate cell migration, flow cytometry to examine chemokine receptor expression, and phospho-ELISA to study consequent signaling pathways in regulatory T cells. Results: Regulatory T cells, but not CD4+CD25-T cells, from AA subjects showed decreased chemotactic responses, specifically to CCL1, in comparison with their healthy control and non-AA counterparts. Decreased CCL1-mediated chemotaxis in AA regulatory T cells was associated with decreased phosphorylation of AKT, a protein involved in chemokine intracellular signaling. Furthermore, the decreased chemotactic response to CCL1 in AA regulatory T cells significantly correlated with asthma severity and decreased pulmonary function in AA subjects. These results provide the first evidence of dysfunction in the chemokine signaling pathway in AA regulatory T cells. Conclusion: The CCL1-specific impaired migration of Treg cells in allergic asthma might contribute to their reduced frequency at sites of airway inflammation. doi:10.1016/j.clim.2009.03.013

OR.8. Role of Sex Hormones and Gender in the Functional Differences of Regulatory and CD8+Suppressor T Cells in SLE Patients Ram Singh, Ravi Dinesh, Antonio La Cava, Bevra Hahn. David Geffen School of Medicine at UCLA, Los Angeles, CA The goal of the present study was to determine the quantity and function of regulatory and suppressor T cells, and the effect of sex hormones on T reg functions in healthy individuals and in SLE patients of both genders. Immunophenotyping of PBMC from SLE patients (n ~ 35) indicated significantly reduced numbers of CD4+CD25hi Foxp3+T cells and CD8+Foxp3+suppressor T cells (p b 0.02) as compared to healthy matched controls (n ~ 17). Numbers of CD4+and CD8+regulatory T cells are decreased in healthy females compared to healthy males (p b 0.01). Both CD4+CD25hi and CD8+CD25hi subsets of males had 3-4-fold higher Foxp3 mRNA compared to females. The in vitro proliferative potential of CD4+T regulatory cells and CD8+T suppressor cells were defective in CFSE staining experiments in SLE patients as compared to the healthy controls (p b 0.001). Foxp3 expression was higher in males than in females PBMCs with and without recombinant TGFb. Stimulation of PBMCs with beta estradiol (30 pg/ml) decreases Foxp3 expression in healthy female but not in age matched healthy male. At higher doses (60, 150 pg/ml) estrogen has little effect in both the sexes. Estrogen decreases Foxp3 mRNA and protein expression in both female and male SLE patients CD4+CD25-T cells (p b 0.05). An Inhibitor of beta estradiol (ER-alpha) increased apoptosis in male SLE patients only. These data suggest that estrogen affect the Tregulatory compartment. These findings may have possible implications in understanding the regulation of disease in relation to gender bias in SLE patients. doi:10.1016/j.clim.2009.03.015