Tph Cells Expanded in Primary Sjögren’s Syndrome

Enhanced co-expression of TIGIT and PD-1 on γδ T cells correlates with clinical features and laboratory parameters in patients with primary Sjögren's syndrome

OBJECTIVES

The research aimed to assess the proportions of Gamma delta (γδ) T cells and the expression levels of CD226, ICOS, CD40L, OX40, TIGIT, LAG-3, Tim-3, and PD-1 on γδ T cells in the peripheral blood of patients diagnosed with primary Sjögren's syndrome (pSS), and to evaluate the clinical significance of these findings.

METHODS

Utilizing flow cytometry, we investigated the proportion of γδ T cells and the expression of CD226, ICOS, CD40L, OX40, TIGIT, LAG-3, PD-1, and Tim-3 on γδ T cells in 37 patients diagnosed with pSS and 28 healthy controls (HC). Moreover, we explored the potential associations between the proportion of γδ T cells, TIGIT + γδ T cells, PD-1 + γδ T cells, and TIGIT + PD-1 + γδ T cells with clinical symptoms and laboratory parameters.

RESULTS

Compared to HC, patients with pSS showed a decreased proportion of γδ T cells, alongside an increased proportion of TIGIT + γδ T cells, PD-1 + γδ T cells, and TIGIT + PD-1 + γδ T cells (p < 0.01). Nevertheless, there were no statistically significant variations noted in the expression levels of CD226, ICOS, CD40L, Tim-3, LAG-3, and OX40 on γδ T cells between two groups (p > 0.05). Furthermore, γδ T cells demonstrated a declining trend in patients with clinical symptoms such as xerostomia, xerophthalmia, decayed teeth, and fatigue, as well as in those with high IgG levels and positivity for anti-SSB/La, anti-SSA/Ro60, and anti-SSA/Ro52. Conversely, TIGIT + γδ T cells, PD-1 + γδ T cells, and TIGIT + PD-1 + γδ T cells exhibited an increasing trend in these patient groups. In correlation analyses with IgG, ESR, CRP, C3, C4, IgA, RF, IgM, and ESSDAI, γδ T cells were observed to have a negative correlation with ESR, IgG and ESSDAI. TIGIT + γδ T cells demonstrated significant positive correlations with IgG, IgA, and ESSDAI. PD-1 + γδ T cells showed positive correlations with ESR, CRP, IgA, and ESSDAI. Furthermore, TIGIT + PD-1 + γδ T cells showed significant positive correlations with ESR, IgG, RF, IgA, and ESSDAI.

CONCLUSION

Our results indicated that patients with pSS exhibited a reduction in γδ T cells alongside elevated expression of TIGIT, PD-1, and their co-expression on γδ T cells. These changes were found to correlate with clinical symptoms and laboratory parameters, suggesting that γδ T cells, TIGIT + γδ T cells, PD-1 + γδ T cells, and especially TIGIT + PD-1 + γδ T cells could potentially serve as diagnostic biomarkers for pSS.

A detailed quantitative analysis of circulating T peripheral and follicular helper lymphocytes in patients with rheumatoid arthritis and systemic lupus erythematosus

INTRODUCTION AND OBJECTIVE

Peripheral and follicular helper T lymphocytes (Tph and Tfh, respectively) have an important role in B cell immune responses and the pathogenesis of rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). Although several studies on the number of Tph and Tfh cells in these conditions have been published, different phenotypes have been employed for their analysis. In this study, we assessed the levels and function of Tph and Tfh cells in blood samples from patients with RA and SLE by using an extended immunophenotype.

MATERIALS AND METHODS

In a cross-sectional pilot study, blood samples from twenty-seven patients with RA and fifteen with SLE, and twenty-six healthy controls were studied. The levels of Tph (CD4+PD-1+CXCR5-CD38+CD69+ICOS+) and Tfh (CD4+PD-1+CXCR5+CD38+CD69+ICOS+) cells were analyzed by flow cytometry. In addition, the function of Tph/Tfh cells was estimated by measuring the synthesis of IL-21 by these lymphocytes as well as the number of circulating plasmablasts (CD19+CD27+CD20-CD38hi).

RESULTS

Increased percentages of Tph and Tfh lymphocytes were detected in patients with RA and SLE. Furthermore, the synthesis of IL-21 tended to be higher in both conditions, and higher levels of plasmablasts were detected in these patients, compared to controls. In patients with SLE, the number of Tph cells was associated with disease activity and with the levels of circulating plasmablasts, whereas in patients with RA a significant correlation between Tph cells and evolution time was observed.

DISCUSSION AND CONCLUSIONS

Our data of Tph and Tfh lymphocytes, based in the analysis of an extended phenotype of these cells, provides further evidence on their involvement in the pathogenesis of RA and SLE.

Occurrence and role of Tph cells in various renal diseases

A new population of peripheral helper T (Tph) cells has been identified and contributed to various autoimmune diseases. Tph cells can secrete interleukin-21 (IL-21), interferon (IFN) and C-X-C motif chemokine ligand 13 (CXCL13) to moderate renal disease. Moreover, Tph cells can congregate in huge numbers and immerse within inflamed tissue. Compared to Tfh cells, Tph cells express high programmed cell death protein 1 (PD-1), major histocompatibility complex II (MHC-II), C-C chemokine receptor 2 (CCR2) and C-C chemokine receptor 5 (CCR5) but often lack expression of the chemokine receptor C-X-C chemokine receptor 5 (CXCR5). They display features distinct from other T cells, which are uniquely poised to promote responses and antibody production of B cells within pathologically inflamed non-lymphoid tissues and a key feature of Tph cells. In this review, we summarize recent findings on the role of Tph cells in chronic kidney disease, acute kidney injury, kidney transplantation and various renal diseases.

Exploring the Role of PD-1 in the Autoimmune Response: Insights into Its Implication in Systemic Lupus Erythematosus

Despite advances in understanding systemic lupus erythematosus (SLE), many challenges remain in unraveling the precise mechanisms behind the disease's development and progression. Recent evidence has questioned the role of programmed cell death protein 1 (PD-1) in suppressing autoreactive CD4+ T cells during autoimmune responses. Research has investigated the potential impacts of PD-1 on various CD4+ T-cell subpopulations, including T follicular helper (Tfh) cells, circulating Tfh (cTfh) cells, and T peripheral helper (Tph) cells, all of which exhibit substantial PD-1 expression and are closely related to several autoimmune disorders, including SLE. This review highlights the complex role of PD-1 in autoimmunity and emphasizes the imperative for further research to elucidate its functions during autoreactive T-cell responses. Additionally, we address the potential of PD-1 and its ligands as possible therapeutic targets in SLE.

Cytotoxic Tph subset with low B-cell helper functions and its involvement in systemic lupus erythematosus

T peripheral helper (Tph) cells are thought to contribute to extra-follicular B cell activation and play a pathogenic role in autoimmune diseases. However, the role of Tph subsets is not fully elucidated. Here, we investigate the immunological functions of Tph subsets and their involvement in systemic lupus erythematosus (SLE). We have defined four Tph subsets (Tph1: CXCR3+CCR6-, Tph2: CXCR3-CCR6-, Tph17: CXCR3-CCR6+, and Tph1-17: CXCR3+CCR6+) and performed RNA sequencing after cell sorting. Tph1 and Tph17 subsets express substantial levels of IL21, indicating B cell helper functions. However, Tph2 and Tph1-17 subsets express low IL21. Interestingly, we have found Tph2 subset express high levels of CX3CR1, GZMB, PRF1, GLNY, S1PR5, TBX21, EOMES, ZNF863, and RUNX3, indicating a feature of CD4+ cytotoxic T lymphocytes. In SLE patients, the frequency of Tph1 and Tph2 subsets are significantly increased and positively correlated with SLE disease activity indexes. Tph1 cells expansion has been observed in patients with cutaneous and musculoskeletal manifestations. On the other hand, Tph2 cell expansion has been found in patients with lupus nephritis in addition to the above manifestations. Our findings imply that Tph1 and Tph2 subsets exert distinct immunological functions and are contributed to the complexity of clinical manifestations in SLE.

The response of CD27+CD38+ plasmablasts, CD24hiCD38hi transitional B cells, CXCR5-ICOS+PD-1+ Tph, Tph2 and Tfh2 subtypes to allergens in children with allergic asthma

BACKGROUND

Allergic asthma is a type I allergic reaction mediated by serum Immunoglobulin E (IgE). B cell-mediated humoral immune response to allergens in the pathophysiology of allergic asthma have not been thoroughly elucidated. Peripheral helper T cells (Tph) and follicular helper T cells (Tfh) promote B cell differentiation and antibody production in inflamed tissues.

OBJECTIVE

To investigate the roles of B cell subsets, Tph cell subsets and Tfh cell subsets in allergic immune responses.

METHODS

Circulating B cell subsets, Tph cell subsets and Tfh cell subsets in 33 children with allergic asthma and 17 healthy children were analyzed using multicolor flow cytometry. The level of serum total IgE was also assessed.

RESULTS

Our study found that CD27+CD38+ plasmablasts and CD24hiCD38hi transitional B cells increased and were correlated with serum total IgE level, CD27- naive B cells and CD24hiCD27+ B cells decreased in children with allergic asthma. CXCR5- Tph, CXCR5-ICOS+ Tph, CXCR5-ICOS+PD-1+ Tph, CXCR5+ICOS+ Tfh and CXCR5+ICOS+PD-1+ Tfh increased in children with allergic asthma. Further analysis showed increased Tph2, Tph17, Tfh2 and Tfh17 subtypes while decreased Tph1 and Tfh1 subtypes in children with allergic asthma. Most interestingly, Tph2 or Tfh2 subtypes had a positive correlation with serum total IgE level.

CONCLUSION

Overall, these results provide insight into the allergens elicited B, Tph or Tfh cell response and identify heretofore unappreciated CD24hiCD38hi transitional B cells, CD24hiCD27+ B cells, CXCR5- Tph, CXCR5-ICOS+PD-1+ Tph, Tph2 subtypes and Tfh2 subtypes response to allergens.

Single-cell transcriptome profiling reveals immune and stromal cell heterogeneity in primary Sjögren's syndrome

Primary Sjögren's syndrome (pSS) is a complex autoimmune disease characterized by lymphocytic infiltration and exocrine dysfunction, particularly affecting the salivary gland (SG). We employed single-cell RNA sequencing to investigate cellular heterogeneity in 11 patients with pSS and 5 non-SS controls. Notably, patients with pSS exhibited downregulated SOX9 in myoepithelial cells, potentially associated with impaired epithelial regeneration. An expanded ACKR1+ endothelial subpopulation in patients with pSS suggested a role in facilitating lymphocyte transendothelial migration. Our analysis of immune cells revealed expanded IGHD+ naive B cells in peripheral blood from patients with pSS. Pseudotime trajectory analysis outlined a bifurcated differentiation pathway for peripheral B cells, enriching three subtypes (VPREB3+ B, BANK1+ B, CD83+ B cells) within SGs in patients with pSS. Fibroblasts emerged as pivotal components in a stromal-immune interaction network, potentially driving extracellular matrix disruption, epithelial regeneration impairment, and inflammation. Our study illuminates immune and stromal cell heterogeneity in patients with pSS, offering insights into therapeutic strategies.

Single-Cell RNA-Sequencing Reveals Peripheral T Helper Cells Promoting the Development of IgG4-Related Disease by Enhancing B Cell Activation and Differentiation

Abnormal B cell differentiation plays a critical role in IgG4-related disease (IgG4-RD), but the underlying mechanism remains largely unknown. We investigated the cell landscape from three IgG4-RD retroperitoneal tissues and three control tissues using single-cell RNA-sequencing. Critical cell type or markers were further validated in the peripheral blood from the patients with IgG4-RD and healthy controls via flow cytometry as well as in the IgG4-RD and control tissue via immunofluorescence staining. The increases in B cells, plasma cells, and CD4+ T cells were found in IgG4-RD retroperitoneal tissue. Importantly, among CD4+ T cells, an increase in CD4+CXCR5-PD1hi peripheral T helper (Tph) cells with a high expression of IL-21 and TIGIT was discovered in IgG4-RD tissue, which was further validated in peripheral blood of the patients with IgG4-RD. The Tph cell and TIGIT+ Tph cell proportion were remarkably higher in active IgG4-RD patients and correlated with disease activity. Moreover, TIGIT+CD4+ cells were able to promote B cell differentiation via IL-21. Our study revealed that Tph cells are increased in IgG4-RD and probably play critical roles in B cell differentiation through TIGIT-IL-21 axis. Peripheral Tph cell and TIGIT+Tph cell are potential markers for IgG4-RD disease activity.

T peripheral helper cells in autoimmune diseases: What do we know?

The interactions between T cells and B cells are essential for antibody responses and the development of autoimmune diseases. Recently, a distinct subset of T cells capable of helping B cells was established in synovial fluid, and they were termed peripheral helper T (Tph) cells. PD-1hiCXCR5−CD4+ Tph cells express high levels of CXCL13, which drives the formation of lymphoid aggregates and tertiary lymphoid structures, ultimately facilitating the local production of pathogenic autoantibodies. Tph and T follicular helper cells share some key features but can be distinguished by their surface markers, transcriptional regulation, and migration capability. We summarize recent findings on Tph cells in this review and provide a perspective on their potential roles in a range of autoimmune diseases. More clinical and in-depth mechanistic investigations of Tph cells may help to improve the understanding of pathogenesis and further provide novel therapeutic targets in autoimmune diseases.