113. Studies on the mechanism of the dysregulation of t-cell interferon- γ production in ANCA-vasculitis patients
Creators: name: Srinivasulu Puli1
name: Hellmark1, Thomas
name: Pettersson1, Åsa
name: Appelgren2, Daniel
name: Mårten Segelmark1,2,3
Publisher: name: Zenodo
Year: 2022
Subjects: Vasculitis
ANCA
Abstracts
Giant Cell Arthritis
MPA
GPA
EGPA
Takayasu
IgA vasculitis

description: <strong>Background: T cells play an important role in pathogenesis of ANCA vasculitis. Predominant presence of CD4<sup>+ </sup>T cell subsets and proinflammatory cytokines such as IFN-γ in inflammatory lesions implies that T cells during remission contribute to autoantibody generation and subsequent disseminated vasculitis. Previously, we have shown that B cells are unable to down regulate IFN-</strong>γ <strong>production </strong>by <strong>activated CD3<sup>+ </sup>T-cell</strong>s from AAV patients during remission, in contrast to healthy control. The aim of this study is to investigate the mechanisfor this dysregulation of IFN-γ production. <br> <strong>Methods:</strong> To reveal mechanisfor B-cell inhibition of T-cell <strong>IFN-γ production, inhibitors of the following molecules were added to co-cultures of cells from healthy controls (HC): </strong>PDL1, CTLA4, IL-10, B- and T- lymphocyte attenuator (BTLA) protein. Sandwich ELISA were used to measure <strong>IFN-γ and other </strong>cytokines in culture supernatants. Intracellular staining for Foxp3 was used to enumerate Treg cell generation. The effect of recombinant IL-10 on <strong>IFN-γ production of isolated T cells was assessed in both HC and AAV patients in remission. </strong>This effect was studied in different T cell subsets (CD3<sup>+</sup>, CD4<sup>+</sup>, CD8<sup>+</sup>,CD45RO<sup>+</sup>, CD45RO<sup>-</sup>, Th1, Th2, Th17) after sorting by FACS. <strong>Results: </strong>The inhibition of IFN-γ in HC (n=4) was attenuated by blocking PDL1, CTLA4, BTLA or IL-10 on activated CD3<sup>+ </sup>T cells in co-culture with B cells. However, this attenuation was markedly higher by blocking the IL-10 receptor compared (343 pg/ml), with the other blockers (298 pg/ml, 287 pg/ml, 265 pg/ml, p=0.028, p=0.027, p=0.057 respectively). Addition of recombinant IL-10 to activated CD3<sup>+ </sup>T-cells increased numbers of Treg cells in both AAV patients (p=0.001, n=10) and HC (p=0.004, n=4), but supressed IFN-γ secretion only in HC; activated T-cells alone vs activated T cell + recombinant IL-10 (395 pg/ml vs 297 pg/ml, p=0.013), not in AAV patients; activated T-cells alone vs activated T cell + recombinant IL-10 (322 pg/ml vs 327 pg/ml, p=0.484). Preliminary data from the T-cell subsets indicate that IFN-γ production is elevated and unresponsive to regulation primarily in the Th1 and Th17 subpopulations in cells from AAV patients (n=3) (regardless of whether they are in remission or active disease). <strong>Conclusions:</strong> Suppression of T-cell’s IFN-γ production is mainly mediated by IL-10 in HC, but in AAV patients this mechanism seeto be absent. The importance of these preliminary findings is unclear but signalling pathways downstream of IFN-γ are possible to target pharmacologically. <strong>Disclosures</strong>: None