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Selected Publication:
Fessler, J.
Functional and epigenetic changes of senescent immune cells in patients with rheumatoid arthritis
Doktoratsstudium der Medizinischen Wissenschaft; Humanmedizin; [ Dissertation ] Graz Medical University; 2015. pp.
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- Authors Med Uni Graz:
- Fessler Johannes
- Advisor:
- Dejaco Christian
- Graninger Winfried
- Gülly Christian
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- Abstract:
- Background/Purpose This work aims at the better understanding of the role of immunosenescence in autoimmune diseases. We therefore focus on T lymphocyte development, homeostasis and aging as a central point of disease pathogenesis and investigate signs of advanced age of T-cells in autoimmune disorders like rheumatoid arthritis as well as the properties of so far unknown senescent T-cell subsets (CD4+CD28-FoxP3+). Methods Prospective, cross-sectional study on 44 patients with RA [mean age 59.3 (±SD 9.9), 77.3% female, SDAI 7.8 (±7.7)] and 35 healthy controls [mean age 56.5 (±9.4), 82.9% female]. To determine prevalences of CD4+CD28-FoxP3+ T cells as well as to test for phenotypic changes, proliferative capacity, cytokine production and apoptosis flow cytometry methods were used. To test for the senescence status TCR diversity was determined by RT-PCR. In vitro generation of senescent Tregs was performed in cell culture experiments. Therefore, normal CD4+CD25+CD127low Tregs were isolated using magnetic cell isolation method and stimulated with anti-CD3/CD28 beads, interleukin (IL) -2 in the presence or absence of TNF-a (100ng/ml) for 7 days. Results 1.7% [0-14.7] of CD4+ T cells were CD28-FoxP3+ in RA patients. This subset, however, was almost absent in healthy individuals [0.3 (0-2.8), p<0.001]. The number of ordinary CD4+FoxP3+ regulatory T cells was not influenced [32 (0.9-83.5) vs. 27.2 (3.9-83.8), p=0.416]. Phenotypic analysis revealed that CD28-FoxP3+ T cells express significantly more surface PD-1 compared to their CD28+ counterparts [17.45% (0-36.4) vs. 5.45% (1.8-13.5), p=0.034], whereas CTLA-4 expression was not different. In addition, CD28-FoxP3+ T cells showed increased production of various cytokines including IL-2, IL-4, IL-10, IL-17, TNF-a and IFN-¿ [all p>0.05]. Further this senescent subset showed reduced proliferative potential [50% (0-93.6) non proliferating cells vs. 4.6% (0-30.6), p=0.001] which is in line with increased apoptosis rate in comparison to CD28+FoxP3+ T cells [22.1% (0-30.8) vs. 4.4% (0-7.8), p<0.001]. TCR diversity was drastically reduced in CD28-FoxP3+ T cells [median TCR diversity score: 84 (36-104) vs. 115 (109-125), p=0.037]. In cell culture experiments, TNF-a was able to down-regulate CD28 [median MFI: 6097 (4309-9298) vs. 8380.5 (6704-13252), p=0.036] and thus generate senescent regulatory CD4+CD28-FoxP3+ T cells. Conclusion We discribe a novel T cell subset which features both senescent as well as regulatory properties. This subset was detected in RA patients but not healthy individuals. Phenotype and function suggest a role or this subset in disease pathogenesis.