Unique expansion of IL-21+ Tfh and Tph cells under control of ICOS identifies Sjögren’s syndrome with ectopic germinal centres and MALT lymphoma

Abstract

ObjectivesTo explore the relevance of T-follicular-helper (Tfh) and pathogenic peripheral-helper T-cells (Tph) in promoting ectopic lymphoid structures (ELS) and B-cell mucosa-associated lymphoid tissue (MALT) lymphomas (MALT-L) in Sjögren’s syndrome (SS) patients.MethodsSalivary gland (SG) biopsies with matched peripheral blood were collected from four centres across the European Union. Transcriptomic (microarray and quantitative PCR) analysis, FACS T-cell immunophenotyping with intracellular cytokine detection, multicolor immune-fluorescence microscopy and in situ hybridisation were performed to characterise lesional and circulating Tfh and Tph-cells. SG-organ cultures were used to investigate functionally the blockade of T-cell costimulatory pathways on key proinflammatory cytokine production.ResultsTranscriptomic analysis in SG identified Tfh-signature, interleukin-21 (IL-21) and the inducible T-cell co-stimulator (ICOS) costimulatory pathway as the most upregulated genes in ELS+SS patients, with parotid MALT-L displaying a 400-folds increase in IL-21 mRNA. Peripheral CD4+CXC-motif chemokine receptor 5 (CXCR5)+programmed cell death protein 1 (PD1)+ICOS+ Tfh-like cells were significantly expanded in ELS+SS patients, were the main producers of IL-21, and closely correlated with circulating IgG and reduced complement C4. In the SG, lesional CD4+CD45RO+ICOS+PD1+ cells selectively infiltrated ELS+ tissues and were aberrantly expanded in parotid MALT-L. In ELS+SG and MALT-L parotids, conventional CXCR5+CD4+PD1+ICOS+Foxp3- Tfh-cells and a uniquely expanded population of CXCR5-CD4+PD1hiICOS+Foxp3- Tph-cells displayed frequent IL-21/interferon-γ double-production but poor IL-17 expression. Finally, ICOS blockade in ex vivo SG-organ cultures significantly reduced the production of IL-21 and inflammatory cytokines IL-6, IL-8 and tumour necrosis factor-α (TNF-α).ConclusionsOverall, these findings highlight Tfh and Tph-cells, IL-21 and the ICOS costimulatory pathway as key pathogenic players in SS immunopathology and exploitable therapeutic targets in SS.

Association between T follicular helper cells and T peripheral helper cells with B-cell biomarkers and disease activity in primary Sjögren syndrome

“…Our results regarding activated Tfh in pSS are consistent with previous studies that have shown an expansion of circulating activated Tfh in patients with pSS, 16 17 mostly in those with extraglandular manifestations and/or high disease activity 7 8 and a correlation between activated Tfh and disease activity. 9 10 On the opposite, in another study, pSS patients had a normal frequency of blood activated Tfh, but an increased level of T follicular regulatory (Tfr) cells and blood Tfr/Tfh ratio.…”

“…Indeed, Tph have now been studied in many auto-immune diseases, such as systemic erythematosus lupus, systemic sclerosis or rheumatoid arthritis, 18–20 but only few data are available in pSS. 16 17 We confirmed their expansion in the blood of pSS patients and our study is one of the first to describe their association with clinical and biological characteristics.…”

“… 9 A recently published article from Pontarini et al described that both Tfh and Tph-cells were enriched in salivary glands with germinal centres from pSS patients. 16 …”

Increased Circulating T Follicular Helper Cells Induced via IL-12/21 in Patients With Acute on Chronic Hepatitis B Liver Failure

“…CD4 + CXCR5 + ICOS + Tfh cells were mildly induced by stimulation dynabeads ® human T-activator CD3/ CD28, and there was a statistically significant increase after the addition of exogenous IL-12 and/or IL-21 (Figures 4A, D). This data is in line with findings that IL-12 and IL-21 are important in differentiation and generation of Tfh cells (19)(20)(21). As expected, exogenous IL-17 has no effect on differentiation of Tfh cells (Figures 4A, D).…”

Transcriptome Sequencing Reveals Potential Roles of ICOS in Primary Sjögren’s Syndrome

“…Moreover, higher fractions of ICOS(+) Tfh cells were observed, and a positive association was found between autoantibody levels and increased level of Tfh cells in pSS compared to controls (Brokstad et al, 2018). Recent research also highlighted Tfh and pathogenic peripheral-helper T-cells (Tph), IL-21, and the ICOS costimulatory pathway as key pathogenic players in SS immunopathology (Pontarini et al, 2020). In addition, low IFN-γ levels and indifferent expression levels of other factors (IL-6, IL-4, and TGFβ1) were found in ELISA, and this controversial finding may be explained by low disease activity in our pSS patients (Karabulut et al, 2018).…”