Background: Sjögren’s disease (SjD) is a systemic autoimmune disorder characterized by lymphocytic infiltrations in the exocrine glands leading to tissue damage and sicca symptoms. Although the pathology of the disease is not yet well elucidated, interferone signature, B-cell hyperactivation, aberrant B-T-cell cross-talk, and altered composition of T-cell subpopulations are thought to be hallmarks of the pathogenesis of SjD. Previously, we reported that naïve CD4+ T-cells exhibit signs of immune cell aging and impaired homeostatic proliferation, thus leading to peripheral lymphopenia, a frequent finding in SjD patients.

Objectives: To identify extrinsic and intrinsic factors that result in a diminished proliferative capacity of naive CD4+ T-cells in SjD using a multi-omics approach.

Methods: Peripheral naive CD4+ T-cells were isolated from venous blood of SjD patients fulfilling 2016 ACR/EULAR classification criteria and matched healthy control subjects (HC). Material from each donor was used for RNA sequencing and HPLC/HRMS untargeted metabolomics. Advance downstream analysis of differentially expressed genes (DEG) and whole transcriptome analysis was carried out. Type I interferone signature score was calculated and association of transcriptome alterations and clinical parameters were determined in the patient´s group. Univariate and multivariate statistical methods were used in the omics data in order to identify potential disease biomarkers and inter-group differences. Naive CD4+ T-cells were cultured in vitro for 14 days to assess their responsiveness to homeostatic T-cell cytokine interleukin (IL)7. Cells treated with IL-7 in combination with IFN α2a + IFNβ1a were used to assess the effect of IFN I on naive CD4+ T-cell homeostasis, senescence status and metabolic rewiring.

Results: Transcriptome analysis identified a prominent type I interferon signature in SjD naive CD4+ T-cells. IFN α1 and IFN β were predicted as the major drivers of transcriptional changes. In vitro, the homeostatic proliferation of naive CD4+ T-cells of HC induced by IL-7 was found to be disrupted by serum from SjD patients or type I interferons, thereby recapitulating the reduced homeostatic proliferation seen in SjD. In addition, IFN I induced cellular senescence measured as senescence-associated β-galactosidase activity, decresed histone H3, and decresed transcripts of pde9a, eomes, lrrn3 and nog. Multivariate analysis of metabolomic analysis revealed robust separation between SjD and HC samples. In vitro, IFN I treatment reduced total cellular protein synthesis. IFN I also decreased glycolytic markers (glucose uptake, surface GLUT1) and glucose dependence that was not compensated via mitochondrial OXPHOS. Interestingly, glucose dependence of SjD cells after IL-7 stimulation was lower than in HC and IFN I treatment did not induce a further decrease. Functionally, IFN I inhibited IL-7-induced pAKT1 signalling.

Conclusions: We show that naïve CD4+ T-cell are dysfunctional in the presence of IFN I. IFN I diminished homeostatic proliferation by impairing the IL-7/IL-7R signalling axis, glucose uptake and glycolysis. Furthermore, exposure to IFN I induced mitochondrial hyperpolarization and reduced protein synthesis- hallmarks of T-cell exhaustion and senescence. These findings suggest how chronic IFN I exposure contributes to the naïve CD4+ T-cell lymphopenia in SjD.

REFERENCES: NIL.

Acknowledgments: NIL.

Disclosure of Interests: None declared.