Date: Monday, November 6, 2017
Session Title: T Cell Biology and Targets in Autoimmune Disease Poster I
Session Type: ACR Poster Session B
Session Time: 9:00AM-11:00AM
Background/Purpose: Systemic sclerosis (SSc) is an auto-immune disorder leading to destructive tissue fibrosis. Abnormal responses of SSc T cells to lipid antigens and low molecular weight phospho-antigens have been observed but not extensively explored. We determined how exposure to cardiolipin, a lipid auto antigen, and zoledronate (zol), an inducer of intracellular phospho-antigens (e.g isopentenyl pyrophosphate), affect cytokine secretion and activation of SSc T cells. We focused on non-conventional innate gd T cells since these: 1. Are oligoclonally expanded in SSc 2. infiltrate damaged organs, and 3. include lipid reactive Vdelta (d)1+ and phospho-antigen reactive Vgamma (g)9+ gammadelta (gd) T cells.
Methods: Peripheral blood mononuclear cells (PBMC) were isolated by ficoll hypaque density centrifugation from 12 SSc patients (SScp) and 13 healthy controls (HC). Expression of CD25, a marker of activation, on Vg9+, Vd1+ and total CD3+ T cells in PBMC cultured for at 2X106 cells/ml 96 hour in RPMI-1640 tissue culture medium supplemented with 10% fetal bovine serum, penicillin streptomycin, and glutamine, (TCM) containing 100 international units of interleukin (IL)-2 and added reagents as indicated, was measured by flow cytometry – as were cell surface binding of CD1d tetramers, and effects of monoclonal antibody (mAb) mediated blockade of CD1d. Intracellular production of anti fibrotic [interferon (IFN) g] and pro fibrotic [IL- 4] cytokines was measured by flow cytometry after overnight incubation of PBMC in medium with added reagents.
Results: Secretion of IFNg (but not IL-4) was suppressed in SSc relative to HC CD3+ and Vg9+ , but not Vd1+ T cells cultured in TCM alone. However, both Vd1+ and Vg9+ T cell IFNg secretion in SSc were relatively reduced by adding cardiolipin (2.5 mg/ml), which, by contrast, augmented IL-4+ SSc Vg9+ T cells. Moreover, IFNg+ SSC Vg9+ T cells were relatively suppressed by zol (2mMol), consistent with subset restricted specific effects of cognate antigens. Conversely, %CD25+ CD3+ and Vd1+ , and to a lesser degree Vg9+ T cells, were elevated significantly in 96 h cultured SSc PBMC compared to HC. Moreover, cardiolipin and zol respectively, significantly suppressed SSc but not HC %CD25+ Vg9+ and Vd1+ (but not total %CD25+CD3+ ) T cells suggesting antigen driven cross inhibitory effects by these gd T cell subsets. These effects could be partially reversed by culture with zol + cardiolipin , whereas this combination more strongly amplified both CD25+ gd T cell subsets of HC. Importantly, SSc and HC Vd1+ T cells > Vd1– T cells were highly reactive with lipid presenting CD1d – tetramers. Furthermore, a CD1d – blocking mAb decreased the zol + cardiolipin enhancement of %CD25+Vd1+ T cells in SSc PBMC cultures
Conclusion: SSc patient Vd1+ and Vg9+ T cell subsets exhibit disturbed and interactive responses to cardiolipin and zol in vitro, mediated in part by CD1d. Thus, the abnormal perception of cardiolipin and phospho-antigens by gd T cells may play a role in the immune pathology in SSc, notably that of pathological fibrosis, warranting further study.
To cite this abstract in AMA style:Bank I, Fisch P, Hidalgo JV, Balbir-Gurman A, Braun-Moscovici Y, Migalovich Sheikhet H. Abnormal Responses of γδ T Cell Subsets to Stimulation with Cardiolipin and Zoledronate in Systemic Sclerosis [abstract]. Arthritis Rheumatol. 2017; 69 (suppl 10). https://acrabstracts.org/abstract/abnormal-responses-of-%ce%b3%ce%b4-t-cell-subsets-to-stimulation-with-cardiolipin-and-zoledronate-in-systemic-sclerosis/. Accessed July 11, 2020.
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