B-cell populations and sub-populations in Sjögren's syndrome

Machine learning approach to single cell transcriptomic analysis of Sjogren's disease reveals altered activation states of B and T lymphocytes

Sjogren's Disease (SjD) is an autoimmune disorder characterized by salivary and lacrimal gland dysfunction and immune cell infiltration leading to gland inflammation and destruction. Although SjD is a common disease, its pathogenesis is not fully understood. In this study, we conducted a single-cell transcriptome analysis of peripheral blood mononuclear cells (PBMC) from patients with SjD and symptomatic non-SjD controls to identify cell types and functional changes involved in SjD pathogenesis. All PBMCs populations showed marked differences in gene expression between SjD patients and controls, particularly an increase in interferon (IFN) signaling gene signatures. T and B cells of SjD patients displayed a depletion of ribosomal gene expression and pathways linked to protein translation. SjD patients had increased frequencies of naive B cells, which featured a unique gene expression profile (GEP) distinct from controls and had hallmarks of B cell hyperactivation. Non-negative matrix factorization (NMF) also identified several non-overlapping GEPs in CD4+ and CD8+ T cells with differential usage in SjD patients and controls. Of these, only the Th1 activation GEP was enriched in T cells of SjD patients whereas the other two GEPs were depleted in T cells, emphasizing the important role of Th1 cells in SjD. Our study provides evidence for aberrant and unique gene expression patterns in both B and T lymphocytes of SjD patients that point to their altered activation states and may provide new insights into the pathogenesis of SjD.

Profiles of peripheral B cell subsets in a cohort of primary Sjögren's syndrome patients and their potential clinical significance

Background/purpose

Primary Sjögren's syndrome is a prototypical autoimmune disease, with B cell dysfunction as a dominant feature. Further insights into distribution of B cell subsets in primary Sjögren's syndrome are urgently required to identify the most appropriate target subpopulation. We aimed to evaluate the profiles of B lymphocyte subpopulations in primary Sjögren's syndrome patients and to investigate their clinical significance.

Materials and methods

Thirty primary Sjögren's syndrome patients and 15 age-and sex-matched healthy controls were recruited. Peripheral B cell subsets were analyzed by flow cytometry.

Results

Compared to healthy controls, circulating CD19+ B cells, CD19+CD20- B cells, CD19+CD27-IgD+ naïve B cells, CD19+IgD+CD38high plasmablasts, CD19+CD24highCD38high transitional B cells and CD19+CD20-CD27+CD38+ plasma cells were elevated in patients with primary Sjögren's syndrome, whereas CD19+CD27+ memory B cells, CD19+CD27-IgD- double negative B cells and CD19+CD24hiCD27+ Bregs were decreased. Furthermore, the percentage of circulating CD19+CD20-CD27+CD38+ plasma cells was positively correlated with serum IgG levels and the proportional area of lymphocytic infiltration of labial gland.

Conclusion

We identified a comprehensive B lymphocyte subset distribution profile in primary Sjögren's syndrome. Moreover, we detected a clinical significance of CD19+CD20-CD27+CD38+ plasma cells, suggesting that these cells might play a key role in disease pathology and represent potential therapeutic targets.

CD4+ T-cell-dependent differentiation of CD23+ follicular B cells contributes to the pulmonary pathology in a primary Sjögren's syndrome mouse model

Introduction

Primary Sjögren's syndrome (pSS) is a systemic autoimmune disease that affects the function of exocrine glands, such as the lacrimal and the salivary glands. Extraglandular lesions and malignant lymphoma also occur during the progressive stage of pSS. We have, herein, focused on the pulmonary lesions of pSS and have aimed clarifying their pathophysiological mechanism by comparing the glandular with the extraglandular lesions observed in a mouse model of pSS.

Results

The histopathological analysis of lung tissues obtained from NFS/sld mice that have undergone neonatal thymectomy was performed. Moreover, in vivo and in vitro experiments were conducted along with immunological analyses in order to characterize the unique phenotypes of the pulmonary lesions identified in these pSS model mice. Inflammatory lesions with a bronchus-associated lymphoid tissue-like structure were identified in the lungs of pSS model mice. In addition, relative to salivary gland lesions, pulmonary lesions showed increased CD23⁺ follicular B (FB) cells. In vitro and pulmonary B cells were more readily driven to CD23⁺ FB cell phenotype than salivary gland B cells in pSS model mice. Furthermore, the CD23⁺ FB cell differentiation was found to be enhanced in a CD4⁺ T-cell-dependent manner under a Th2-type condition in the lungs of herein examined pSS model mice.

Discussion

A Th2-type response in the pSS lung may promote the progression of autoimmune lesions through an enhanced abnormal differentiation of B cells.

Correlations between the histopathological alterations in minor salivary glands and the clinically suspected Sjögren's syndrome

In sicca syndrome patients the xerostomia, xerophthalmia and the serological findings may strongly suggest the autoimmune Sjögren's syndrome, but the histological findings in the labial salivary gland biopsies do not always justify the suspected diagnosis. The aim of this study was to compare the histomorphological changes and the clinical findings in patients with pathologically established Sjögren's syndrome and in cases with negative histology. A total of 133 labial biopsies have been retrospectively evaluated from 2015 to May 2022, and the characteristic Sjögren's lesions were found in 67 cases. According to the clinical data, 34 cases proved to be primary, and 33 were associated ("secondary") forms. In 66 cases, the histology did not justify Sjögren's syndrome; a significant acinar loss, fibrolipomatous infiltration, and mild sialadenitis had led to the clinical symptoms. In Sjögren's histologies, the acinar loss was detected in just 31.8% of cases, which might indicate that the diminished saliva production represents immune-mediated hypofunction rather than direct damage of the acini. This is the first systemic study in Hungary investigating the correlation between pathological alterations and clinical findings.

Hypocomplementemia in primary Sjogren’s syndrome: association with serological, clinical features, and outcome

Objective

The aim of the present study was to assess the clinical characteristic of hypocomplementemia (HC) in primary Sjogren’s syndrome (pSS), and to address possible risk factors and the prognosis associated with HC in pSS patients.

Methods

pSS patients with HC in Hebei General Hospital from September 2016 to March 2019 were retrospectively analyzed and compared to those with normocomplementemia (NC). Logistic regression analysis was used to detect risk factors.

Results

Of the 333 patients with pSS, 84 patients (25.23%) were presented with HC at diagnosis. The presence of hyper-IgG and anti-Ro52 antibodies was significantly more common in patients with HC. In addition to systemic involvement, pSS patients with HC had more hematological, renal, and nervous system involvement, and received more immunosuppressant treatments than NC group (p < 0.05). ESSDAI score was significantly higher in patients with HC (p < 0.05). Multivariate logistic analysis indicated that leukopenia (OR = 2.23) and hyper-IgG (OR = 2.13) were independent risk factors for pSS with HC. In addition, profound CD16/CD56+ NK-cell lymphopenia was found in pSS-HC patients. More pSS patients developed SLE in the HC group than NC group (4.76% vs. 0.80%, p = 0.04) during the follow-up.

Conclusion

HC was not an uncommon manifestation of pSS and had an independent association with the main clinical and immunological features. Patients with pSS-HC had an increased possibility to develop SLE that required more positive treatment with glucocorticoids and immunosuppressants.

Key Points:

• Hypocomplementemia had an independent association with the main clinical and immunological features in primary Sjogren’s syndrome patients.

• ESSDAI score was significantly higher in patients with hypocomplementemia.

• The pSS patients with hypocomplementemia had an increased possibility to develop SLE.

Identification of the key genes and pathways involved in B cells in primary Sjögren' s syndrome

Primary Sjögren’ s syndrome (pSS) is a relatively common autoimmune disease, which mainly involves the exocrine glands, causing dry eye, dryness of mouth, fatigue and pain in the joints, thus severely affecting the normal lives of patients. B cell populations are considered to play an important role in their pathogenesis and pSS patients are generally characterized by exhibiting biological signs of B cell activation. Moreover, another important characterized change in the peripheral blood of pSS patients is found to be the decreased number of circulating memory B cells. However, the mechanisms underlying the B cell activation and the decreased level of circulating memory B cells in pSS patients are still unclear. Therefore, we identified key genes and pathways involved in B cells in pSS through a combination of several bioinformatic approaches including Cell-type Identification By Estimating Relative Subsets Of RNA Transcripts (CIBERSORT) and weighted gene co-expression network analysis (WGCNA) using gene expression data of pSS patients and controls from an open database Gene Expression Omnibus (GEO). The results may provide some novel insights into the pathogenesis of pSS. Moreover, we constructed and validated a diagnostic model for pSS by using the expression patterns of these key genes, which may assist clinicians in diagnosing pSS.

Clinical features and risk factors of Raynaud's phenomenon in primary Sjögren's syndrome

Objective

The aim at the current study was to investigate the clinical characteristics and risk factors of Raynaud’s phenomenon (RP) in patients with primary Sjögren’s syndrome (pSS).

Methods

Retrospective analysis of the medical records of 333 new-onset pSS patients was performed. Demographic, clinical, and serological data were compared between individuals with and without RP. Logistic regression analysis was used to identify risk factors.

Results

RP was present in 11.41% of the pSS patients. pSS-RP patients were younger (49.74±14.56 years vs. 54.46±13.20 years, p=0.04) and exhibited higher disease activity (11 [5.75–15] vs. 7 [4–12], p=0.03) than those without. The prevalence of lung involvement was significantly higher in pSS patients with RP (60.53% vs. 17.29%; p<0.001). A significantly higher proportion of patients with pSS-RP tested positive about antinuclear (ANA), anti-RNP, and anti-centromere antibodies (ACA) compared to those without (p=0.003, <0.001, and 0.01, respectively). Multivariate analysis identified lung involvement (odds ratio [OR]=8.81, 95% confidence interval [CI] 2.02–38.47; p=0.04), anti-RNP positive status (OR=79.41, 95% CI 12.57–501.78; p<0.0001), as well as ACA (OR=13.17, 95% CI 2.60–66.72; p=0.002) as prognostic factors for pSS-RP.

Conclusion

The presence of RP defined a subset of pSS with a unique phenotype, manifesting as increased lung involvement and a higher frequency of anti-RNP antibodies and ACA, as well as greater disease activity. These results suggest that RP has clinical and prognostic value of pSS patients. Further prospective studies with a larger number of subjects are warranted to confirm our findings and assess the prognostic and treatment implications of RP in pSS patients.

Key Points • Raynaud’s phenomenon (RP) was present in 38 (11.41%) of 333 patients with primary Sjögren’s syndrome (pSS), with patients with RP exhibiting a younger age and higher disease activity. • The presence of RP indicates a subset of pSS with a unique phenotype, with manifestations including increased lung involvement and a higher frequency of anti-RNP antibodies and anti-centromere antibodies. • Patients with pSS and RP need close follow-up and long-term observation (including assessment of microangiopathy), with specific attention paid to the possible development of clinical features of systemic sclerosis.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10067-021-05749-w.

Innate Immunity and Biological Therapies for the Treatment of Sjögren's Syndrome

Sjögren's syndrome (SS) is a systemic autoimmune disorder affecting approximately 3% of the population in the United States. This disease has a female predilection and affects exocrine glands, including lacrimal and salivary glands. Dry eyes and dry mouths are the most common symptoms due to the loss of salivary and lacrimal gland function. Symptoms become more severe in secondary SS, where SS is present along with other autoimmune diseases like systemic lupus erythematosus, systemic sclerosis, or rheumatoid arthritis. It is known that aberrant activation of immune cells plays an important role in disease progression, however, the mechanism for these pathological changes in the immune system remains largely unknown. This review highlights the role of different immune cells in disease development, therapeutic treatments, and future strategies that are available to target various immune cells to cure the disease.

A Novel Proposal of Salivary Lymphocyte Detection and Phenotyping in Patients Affected by Sjogren's Syndrome

A preliminary evaluation of the parotid secretion cellular composition in patients with Sjogren’s Syndrome (SS) and a diagnostic accuracy assessment of salivary lymphocyte detection and immunophenotyping in Sjogren’s Syndrome diagnosis and prognosis were performed. The study included 40 consecutive patients, aged 19–60 years, with parenchymal sialadenitis associated with Sjogren’s Syndrome, and 20 healthy donors. The exclusion criteria were exacerbation of sialadenitis, chronic infections, malignant neoplasms, and lymphoproliferative diseases. The standard diagnostic tests were minor salivary gland biopsy and parotid sialography. Immunophenotyping of parotid secretion lymphocytes was performed by multicolor flow cytometry. Lymphocytes were detectable in parotid secretion of patients affected by Sjogren’s Syndrome, both primary (pSS) and secondary (sSS) form, but not in that from healthy donors. Sensitivity, specificity, positive, and negative predictive values of lymphocytes detection in parotid saliva were 77.5%, 100%, 100%, and 69%, respectively. The mean numbers of the total T-cell population, T-helper cells, and T-cytotoxic cells were 71.7%, 41.6%, and 53%, respectively. The immunophenotype of lymphocytes obtained by patients’ parotid flow resembles the immunophenotypes of glandular biopsies currently known. Our preliminary data suggest the use of saliva as an alternative and non-invasive method for evaluating the prognosis of Sjogren’s Syndrome.

Is There a Future for Anti-CD38 Antibody Therapy in Systemic Autoimmune Diseases?

CD38 is a type II glycoprotein highly expressed on plasmablasts, short-lived and long-lived plasma cells, but weakly expressed on other lymphoid cells, myeloid cells and non-hematopoietic cells. This expression pattern makes CD38 an interesting target for a targeted therapy aiming to deplete antibody-producing plasma cells. We present data suggesting that anti-CD38 therapy may be effective for the prevention at the preclinical stage and for the treatment of established autoimmune diseases, such as systemic lupus erythematosus, systemic sclerosis, Sjögren’s syndrome and anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis. Given the high unmet need for efficacious disease-modifying treatment in these diseases, studies are warranted to determine if anti-CD38 antibody-based therapies may delay or prevent the disease progression of systemic autoimmune diseases.

Elevated CCL19/CCR7 Expression During the Disease Process of Primary Sjögren's Syndrome

Primary Sjögren's syndrome (pSS) is a common chronic autoimmune disease characterized by a high prevalence of autoantibodies and lymphocyte-mediated exocrine gland damage. To enhance our understanding of the mechanisms underlying the progression of the disease and to discover potential biomarkers for the early diagnosis of pSS, we applied RNA sequencing to compare the gene expression patterns in minor salivary glands between pSS patients and non-pSS. A total of 293 differentially expressed genes (DEGs) were detected in pSS vs. non-pSS (FDR < 0.05, fold changes > 2). Of these DEGs, 285 (97.26%) were up-regulated, with most being involved in immune system activation, especially in the formation of the immunological synapse. Significantly elevated CCL19/CCR7 expression in the salivary gland was found to be related to anti-Sjögren's syndrome-related antigen A (SSA) antibody and IgG levels in pSS patients, which was further confirmed in a larger cohort. Up-regulated gene expression showed strong discriminatory accuracy in identifying pSS with area under the curve of 0.98 using receiver operating characteristic curve analysis. In conclusion, gene expression changes in pSS include strong markers of immunological activation and have good discriminatory power in identifying patients with pSS.

Association between memory B-cells and clinical and immunological features of primary Sjögren's syndrome and Sicca patients

B-cells play a pivotal role in primary Sjögren's syndrome (pSS) pathogenesis. We aim to (1) evaluate the distribution of B-lymphocyte subpopulations in pSS and Sicca patients, (2) establish cut-off points that discriminate pSS from controls, (3) evaluate the association between memory B-cells and phenotypic features in pSS. We included 57 pSS patients, 68 Sicca and 24 healthy controls. Circulating B-cells were characterized by flow cytometry as naïve and memory subsets and classified from Bm1 to Bm5. Compared to controls, pSS patients had lower percentages (29.5 vs 44.4%) and absolute numbers (47 vs 106 cells/µl) of memory B-cells. Through ROC curves, a cut-off of ≤ 58 total memory B-cells/µl yielded a specificity of 0.88 and a sensitivity of 0.60 for pSS, and was met by 59.6% of pSS patients, 38.8% of Sicca and 12.5% of controls. A cut-off of < 23.5 Switched-memory B-cells/µl yielded a specificity of 0.88 and a sensitivity of 0.54 and was met by 54.4% of pSS patients, 37.3% of Sicca and 12.5% of controls. In pSS, lower total memory B-cells count was associated with longer disease duration (14.3 vs 8.1 years, p = 0.006) and more active disease profile, as evaluated by the European League Against Rheumatism (EULAR) Sjögren's Syndrome Disease Activity Index (ESSDAI) (3.1 vs 1.4, p = 0.043). Decreased numbers of memory B-cells clearly discriminated pSS from controls and can also have prognostic value. It remains to be clarified whether Sicca patients with decreased memory B-cells represent pSS and if B-cell profiling could help in the diagnosis of pSS.

B cells in the pathogenesis of primary Sjögren syndrome

Primary Sjögren syndrome (pSS) is a prototypical autoimmune disease. The involvement of B cells in the pathogenesis of pSS has long been suspected on the basis of clinical observations that include the presence of serum autoantibodies, hypergammaglobulinaemia, increased levels of free light chains and increased risk of B cell lymphoma. Moreover, the composition of the B cell subset is altered in pSS. In this Review, we discuss the mechanisms that support the increased activation of B cells in pSS, including genetic and epigenetic factors and environmental triggers that promote B cell activation via the innate immune system. B cell activating factor (BAFF, also known as TNF ligand superfamily member 13B) is at the crossroads of this process. An important role also exists for the target tissue (exocrine glands, namely the salivary and lachrymal glands), which promotes local B cell activation. This continuous stimulation of B cells is the main driver of lymphomatous escape. Identification of the multiple steps that support B cell activation has led to the development of promising targeted therapies that will hopefully lead to the development of an efficient therapeutic strategy for pSS.

The relationship between the presence of autoantibodies, indicators of local and systemic inflammation, the serum concentration of B-cell activating factor (BAFF) and the intensity of salivary gland infiltration in patients with primary Sjögren's syndrome - a preliminary study

OBJECTIVES

The aim of this study was to find markers related to activation of B cells, which show a correlation with the systemic inflammation markers - erythrocyte sedimentation rate and C-reactive protein and with the intensity of in situ inflammation.

MATERIAL AND METHODS

Forty-one primary Sjögren's syndrome (pSS) patients (33 female, 8 male) of the mean age 52.9 ±15 years were included. A group of 20 healthy volunteers was applied as a control. Erythrocyte sedimentation rate (ESR), concentration of gamma-globulins, C-reactive protein (CRP) and rheumatoid factor (RF) were measured by routine laboratory tests. Titres of antinuclear antibodies (ANAs) were determined by the indirect immunofluorescence method, while anti-SS-A/SS-B antibodies were detected by both the dot-blot method and an enzyme immunoassay. The concentrations of BAFF in sera were measured by sandwich ELISA. Biopsies of minor salivary glands were taken and the focus score (FS) was calculated. Correlations between quantitative variables were assessed using the Spearman correlation coefficient (r).

RESULTS

Serum concentrations of BAFF was significantly higher in the pSS patients than in the control group. The study revealed a statistically significant correlation between ANAs titre and the FS (r = 0.421). Anti-SS-A/Ro and anti-SS-B/La antibodies positively correlated with ESR. There was also a positive correlation between the gamma globulin level and the titres of all tested autoantibodies.

CONCLUSIONS

The positive correlation between ANAs and FS confirms the importance of these autoantibodies in the local inflammatory process. The positive correlation between anti-SS-A/SS-B antibodies and ESR suggests involvement of these antibodies in generalization of the inflammatory response. In the pSS group serum concentrations of BAFF were statistically significantly higher than healthy volunteers. All presented results confirm the role of activity of B cells in the course of pSS.

Primary Sjögren's syndrome related optic neuritis

AIM

To determine the clinical features, diagnosis and treatment of the primary Sjögren syndrome (SS) related optic neuritis.

METHODS

The clinical data of 8 patients (12 eyes) with primary SS related optic neuritis were analyzed retrospectively.

RESULTS

Eight of 128 consecutive patients with optic neuritis resulted from varied causes fulfilled the diagnostic criteria for the primary SS. They presented initially with the signs and symptoms of non-specific optic neuritis, and 5 patients presenting without dryness showed a chronic inflammation of submandibular gland or parotid gland, and lymphocyte infiltration was demonstrated by labial gland biopsy in 2 patients. There were serum positive titers for anti-Sjögren syndrome A (SSA) in 7 patients and anti-Sjögren syndrome B (SSB) in 8 patients. Anti-aquaporin-4 (AQP4) antibody was negative in all the 8 patients. Both glucocorticoids and immunosuppressive agent were administered, and visual acuity elevated in 8 eyes (66.7%), 3 patients (37.5%) recurred in the follow-up.

CONCLUSION

Primary SS related optic neuritis is less common and easily misdiagnosed. The conventional therapies for optic neuritis could not control the recurrence.

Analysis of anti-HLA antibodies in sensitized kidney transplant candidates subjected to desensitization with intravenous immunoglobulin and rituximab

BACKGROUND

Preexisting donor-specific antibodies against human leukocyte antigens are major risk factors for acute antibody-mediated and chronic rejection of kidney transplant grafts. Immunomodulation (desensitization) protocols may reduce antibody concentration and improve the success of transplant. We investigated the effect of desensitization with intravenous immunoglobulin and rituximab on the antibody profile in highly sensitized kidney transplant candidates.

METHODS

In 31 transplant candidates (calculated panel-reactive antibody [cPRA], 34%-99%), desensitization included intravenous immunoglobulin on days 0 and 30 and a single dose of rituximab on day 15. Anti-human leukocyte antigen antibodies were analyzed before and after desensitization.

RESULTS

Reduction of cPRA from 25% to 50% was noted for anti-class I (5 patients, within 20-60 days) and anti-class II (3 patients, within 10-20 days) antibodies. After initial reduction of cPRA, the cPRA increased within 120 days. In 24 patients, decrease in mean fluorescence intensity of antibodies by more than 50% was noted at follow-up, but there was no reduction of cPRA. Rebound occurred in 65% patients for anti-class I antibodies at 350 days and anti-class II antibodies at 101 to 200 days. Probability of rebound effect was higher in patients with mean fluorescence intensity of more than 10,700 before desensitization, anti-class II antibodies, and history of previous transplant.

CONCLUSIONS

The desensitization protocol had limited efficacy in highly sensitized kidney transplant candidate because of the short period with antibody reduction and high frequency of rebound effect.