Single-cell-level protein analysis revealing the roles of autoantigen-reactive B lymphocytes in autoimmune disease and the murine model

Single cell analysis in systemic sclerosis - A systematic review

In recent years, rapid advances in research methods have made single cell analysis possible. Systemic sclerosis (SSc), a disease characterized by the triad of immune abnormalities, fibrosis, and vasculopathy, has also been the subject of various analyses. To summarize the results of single cell analysis in SSc accumulated to date and to deepen our understanding of SSc. Four databases were used to perform a database search on 23rd June 2023. Assessed Grading of Recommendations Assessment, Development and Evaluation certainty of evidence were performed according to PRISMA guidelines. The analysis was completed on July 2023. 17 studies with 358 SSc patients were included. Three studies used PBMCs, six used skin, nine used lung with SSc-interstitial lung diseases (ILDs), and one used lung with SSc-pulmonary arterial hypertension (PAH). The cells studied included immune cells such as T cells, natural killer cells, monocytes, macrophages, and dendritic cells, as well as endothelial cells, fibroblasts, keratinocytes, alveolar type I cells, basal epithelial cells, smooth muscle cells, mesothelial cells, etc. This systematic review revealed the results of single cell analysis, suggesting that PBMCs, skin, SSc-ILD, and SSc-PAH show activation and dysfunction of cells associated with immune-abnormalities, fibrosis, and vasculopathy, respectively.

The role of B cells in systemic sclerosis

Systemic sclerosis (SSc) is a rare and refractory systemic disease characterized by fibrosis and vasculopathy in the presence of autoimmune abnormalities. While the exact cause of SSc is incompletely understood, the specific autoantibodies identified in SSc are closely linked to disease severity and prognosis, indicating a significant role of autoimmune abnormalities in the pathogenesis of SSc. Although the direct pathogenic mechanisms of autoantibodies in SSc are not fully elucidated, numerous prior investigations have demonstrated the involvement of B cells in the pathogenesis of SSc through various mechanisms. Additionally, several clinical trials have explored the efficacy of B-cell depletion therapy for SSc, with many reporting positive outcomes. However, the role of B cells in SSc pathogenesis is multifaceted, as they can both promote inflammation and exert inhibitory functions. This article provides an overview of the involvement of B cells in SSc development, incorporating the latest research findings.

Apremilast Decreased Proinflammatory Cytokines and Subsequently Increased Inhibitory ones in Psoriasis: A Prospective Cohort Study

Abstract is missing (Short communication)

CD32 (FcγRIIB) expression is low on CD21low B cells from systemic sclerosis patients with digital ulcers, interstitial lung disease, and anti-topoisomerase I autoantibodies

CD21low B cells have recently been found increased in SSc-associated digital ulcers (DUs) or interstitial lung disease (ILD). To further characterize CD21low B cells which encompass autoreactive cells, we analyzed their expression of the inhibitory CD32 receptor in SSc. Peripheral blood mononuclear cells from 27 patients with SSc and 15 age-and sex-matched healthy controls (HCs) were analyzed with multicolor flow cytometry. CD21low B cells were significantly increased in patients with DUs (51.3%) compared to HCs (28.1%) and in patients with ILD (53.1%) compared to HCs. CD21lowCD32low B cells were significantly increased in patients with DUs (23.8%) compared to HCs (4.4%), in patients with ILD (28.4%) compared to HCs, and in anti-topoisomerase I (+) patients (21.5%) compared to HCs and to anti-topoisomerase I (-) patients (2.4%). Autoreactive B cells recognizing Topoisomerase I were predominantly within CD32low cell fraction. Our study further supports the autoreactive status of CD21lowCD32low B cells in SSc patients.

Theoretical Studies of DNA Microarray Present Potential Molecular and Cellular Interconnectivity of Signaling Pathways in Immune System Dysregulation

Autoimmunity is defined as the inability to regulate immunological activities in the body, especially in response to external triggers, leading to the attack of the tissues and organs of the host. Outcomes include the onset of autoimmune diseases whose effects are primarily due to dysregulated immune responses. In past years, there have been cases that show an increased susceptibility to other autoimmune disorders in patients who are already experiencing the same type of disease. Research in this field has started analyzing the potential molecular and cellular causes of this interconnectedness, bearing in mind the possibility of advancing drugs and therapies for the treatment of autoimmunity. With that, this study aimed to determine the correlation of four autoimmune diseases, which are type 1 diabetes (T1D), psoriasis (PSR), systemic sclerosis (SSc), and systemic lupus erythematosus (SLE), by identifying highly preserved co-expressed genes among datasets using WGCNA. Functional annotation was then employed to characterize these sets of genes based on their systemic relationship as a whole to elucidate the biological processes, cellular components, and molecular functions of the pathways they are involved in. Lastly, drug repurposing analysis was performed to screen candidate drugs for repositioning that could regulate the abnormal expression of genes among the diseases. A total of thirteen modules were obtained from the analysis, the majority of which were associated with transcriptional, post-transcriptional, and post-translational modification processes. Also, the evaluation based on KEGG suggested the possible role of TH17 differentiation in the simultaneous onset of the four diseases. Furthermore, clomiphene was the top drug candidate for regulating overexpressed hub genes; meanwhile, prilocaine was the top drug for regulating under-expressed hub genes. This study was geared towards utilizing transcriptomics approaches for the assessment of microarray data, which is different from the use of traditional genomic analyses. Such a research design for investigating correlations among autoimmune diseases may be the first of its kind.

The role of dermal fibroblasts in autoimmune skin diseases

Fibroblasts are an important subset of mesenchymal cells in maintaining skin homeostasis and resisting harmful stimuli. Meanwhile, fibroblasts modulate immune cell function by secreting cytokines, thereby implicating their involvement in various dermatological conditions such as psoriasis, vitiligo, and atopic dermatitis. Recently, variations in the subtypes of fibroblasts and their expression profiles have been identified in these prevalent autoimmune skin diseases, implying that fibroblasts may exhibit distinct functionalities across different diseases. In this review, from the perspective of their fundamental functions and remarkable heterogeneity, we have comprehensively collected evidence on the role of fibroblasts and their distinct subpopulations in psoriasis, vitiligo, atopic dermatitis, and scleroderma. Importantly, these findings hold promise for guiding future research directions and identifying novel therapeutic targets for treating these diseases.

Ultrahigh frequencies of peripherally matured LGI1- and CASPR2-reactive B cells characterize the cerebrospinal fluid in autoimmune encephalitis

Intrathecal synthesis of central nervous system (CNS)-reactive autoantibodies is observed across patients with autoimmune encephalitis (AE), who show multiple residual neurobehavioral deficits and relapses despite immunotherapies. We leveraged two common forms of AE, mediated by leucine-rich glioma inactivated-1 (LGI1) and contactin-associated protein-like 2 (CASPR2) antibodies, as human models to comprehensively reconstruct and profile cerebrospinal fluid (CSF) B cell receptor (BCR) characteristics. We hypothesized that the resultant observations would both inform the observed therapeutic gap and determine the contribution of intrathecal maturation to pathogenic B cell lineages. From the CSF of three patients, 381 cognate-paired IgG BCRs were isolated by cell sorting and scRNA-seq, and 166 expressed as monoclonal antibodies (mAbs). Sixty-two percent of mAbs from singleton BCRs reacted with either LGI1 or CASPR2 and, strikingly, this rose to 100% of cells in clonal groups with ≥4 members. These autoantigen-reactivities were more concentrated within antibody-secreting cells (ASCs) versus B cells (P < 0.0001), and both these cell types were more differentiated than LGI1- and CASPR2-unreactive counterparts. Despite greater differentiation, autoantigen-reactive cells had acquired few mutations intrathecally and showed minimal variation in autoantigen affinities within clonal expansions. Also, limited CSF T cell receptor clonality was observed. In contrast, a comparison of germline-encoded BCRs versus the founder intrathecal clone revealed marked gains in both affinity and mutational distances (P = 0.004 and P < 0.0001, respectively). Taken together, in patients with LGI1 and CASPR2 antibody encephalitis, our results identify CSF as a compartment with a remarkably high frequency of clonally expanded autoantigen-reactive ASCs whose BCR maturity appears dominantly acquired outside the CNS.

Optimal treatments and outcome measures of palmoplantar pustulosis: A systematic review and network meta-analysis-based comparison of treatment efficacy

Few studies have made direct comparisons between treatments for palmoplantar pustulosis (PPP); therefore, it is difficult to select the best treatment for each patient. To determine the best therapy and to compare reported measures of efficacy in clinical trials of systemic treatments for PPP in this systematic review and network meta-analysis. Six databases were used to perform database search on 10 July 2022. Randomized controlled trials (RCTs) were identified through a systematic literature search. The titles and abstracts of articles were initially screened for inclusion by two authors independently using our predetermined criteria. The full texts of selected articles were then independently assessed for inclusion in a blinded fashion. Disagreement between the authors was resolved by consensus. Data were abstracted in duplicate. Random-effects model was accepted to perform network meta-analysis. Assessed Grading of Recommendations Assessment, Development and Evaluation certainty of evidence were performed according to the PRISMA guidelines. The analysis was completed in July 2022. The primary outcome was the change of PPP Area and Severity Index (PPPASI) from baseline and the secondary outcome was the achievement of PPPASI-50 response. Seven RCTs with 567 patients were included. Guselkumab 100 mg was the one with the highest probability of reaching the proposed outcomes (mean difference [MD], -8.00; 95% confidence interval [CI], 4.88-11.11), while the achievement of PPPASI-50 response did not show a significant difference (odds ratio [OR], 3.79; 95% CI, 0.51-28.37). Guselkumab 200 mg was next to 100 mg of reaching the proposed outcomes (MD, -4.71; 95% CI, 2.12-7.30), while the achievement of PPPASI-50 response did not show a significant difference (OR, 2.34; 95% CI, 0.48-11.43). Network meta-analysis showed guselkumab 100 mg was the treatment with the highest probability of reaching both PPPASI and PPPASI-50 outcomes. Absolute PPPASI may be more appropriate as an outcome than PPPASI-50.

Combined Use of Tocilizumab and Mesenchymal Stem Cells Attenuate the Development of an Anti-HLA-A2.1 Antibody in a Highly Sensitized Mouse Model

Sensitization to HLA can result in allograft loss for kidney transplantation (KT) patients. Therefore, it is required to develop an appropriate desensitization (DSZ) technique to remove HLA-donor-specific anti-HLA antibody (DSA) before KT. The aim of this research was to investigate whether combined use of the IL-6 receptor-blocking antibody, tocilizumab (TCZ), and bone-marrow-derived mesenchymal stem cells (BM-MSCs) could attenuate humoral immune responses in an allo-sensitized mouse model developed using HLA.A2 transgenic mice. Wild-type C57BL/6 mice were sensitized with skin allografts from C57BL/6-Tg (HLA-A2.1)1Enge/J mice and treated with TCZ, BM-MSC, or both TCZ and BM-MSC. We compared HLA.A2-specific IgG levels and subsets of T cells and B cells using flow cytometry among groups. HLA.A2-specific IgG level was decreased in all treated groups in comparison with that in the allo-sensitized control (Allo-CONT) group. Its decrease was the most significant in the TCZ + BM-MSC group. Regarding the B cell subset, combined use of TCZ and BM-MSC increased proportions of pre-pro B cells but decreased proportions of mature B cells in BM (p < 0.05 vs. control). In the spleen, an increase in transitional memory was observed with a significant decrease in marginal, follicular, and long-lived plasma B cells (p < 0.05 vs. control) in the TCZ + BM-MSC group. In T cell subsets, Th2 and Th17 cells were significantly decreased, but Treg cells were significantly increased in the TCZ+BM-MSC group compared to those in the Allo-CONT group in the spleen. Regarding RNA levels, IL-10 and Foxp3 showed increased expression, whereas IL-23 and IFN-γ showed decreased expression in the TCZ + BM-MSC group. In conclusion, combined use of TCZ and BM-MSC can inhibit B cell maturation and up-regulate Treg cells, finally resulting in the reduction of HLA.A2-specific IgG in a highly sensitized mouse model. This study suggests that the combined use of TCZ and BM-MSC can be proposed as a novel strategy in a desensitization protocol for highly sensitized patients.

Systemic sclerosis is a risk factor of incident psoriasis: results from a nationwide cohort study

Objective

Although the co-existence of systemic sclerosis (SSc) and psoriasis (PsO) has been reported, the risk relationship between the two diseases remains unclear. We aimed to assess whether SSc is associated with the risk of incident PsO.

Methods

From the Korean National Health Insurance Service database, 4,933 patients with SSc and 24,665 age- and sex-matched controls were selected. Hazard ratios (HRs) and 95% confidence intervals (CIs) for incident PsO were estimated using multivariable Cox proportional hazard models adjusted for known risk factors of PsO. Further, we selected individuals whose health check-up data were available (2,355 patients with SSc and 11,775 age- and sex-matched controls). In this population, we further adjusted for additional risk factors of PsO using the health check-up data.

Results

In the analysis of 4,933 patients with SSc and 24,665 age- and sex-matched controls, incidence rates of PsO in patients with SSc and controls were 10.26 and 3.20 per 1,000 person-years, respectively. After adjusting for risk factors of PsO, patients with SSc had a significantly higher risk of incident PsO (adjusted HR: 3.055 [95% CI: 2.597, 3.594]). Moreover, in the analysis of individuals who had health check-up data, additional risk factors of PsO were further adjusted; the result also showed that patients with SSc have a significantly higher risk of incident PsO (adjusted HR: 2.820 [95% CI: 2.207, 3.603]).

Conclusion

Patients with SSc had a 3-fold higher risk of developing incident PsO than controls, independent of known risk factors of PsO.

Association of IL-17 serum levels with clinical findings and systemic lupus erythematosus disease activity index

The current study aims to investigate the relationship betweSen serum IL-17 (IL-17) levels and systemic lupus erythematosus disease activity index (SLE-DAEI) in systemic lupus erythematosus (SLE) patients. In this case-control study, 36 patients with SLE and 40 healthy individuals matched for age and sex were included as the control group. The study measured serum IL-17 in both groups. The correlation between serum IL-17 with disease activity (as per SLE-DAI) and organ involvement in SLE patients. The case group in this study consisted of 4 males and 32 females with a mean age of 35 (17-54) years old, and the control group included six males and 34 females with a mean age of 37 (25-53) years old (p = .35). Serum IL-17 was higher in the cases than in the controls (536 pg/mL vs. 110 pg/mL; p < .001). There was a positive correlation between the serum levels of IL-17 and disease activity index (p < .001, rho = 0.93) among cases. Additionally, the serum levels of IL-17 were higher in patients with renal (p = .003) or central nervous system involvement (p < .001) than in patients without such involvement. Serum Il-17 is associated with SLE, and its serum levels correlate positively with the disease activity and renal and nervous system involvement.

Utility of nailfold capillary assessment for predicting pustulotic arthro-osteitis in palmoplantar pustulosis based on a prospective cohort study

BACKGROUND

Pustulotic arthro-osteitis (PAO) is 1 of the most serious comorbidities associated with palmoplantar pustulosis (PPP). Risk factors of PAO development are not well-known.

OBJECTIVE

To evaluate the clinical significance of nailfold capillary (NFC) changes in patients with PPP.

METHODS

We conducted a prospective cohort study in a population of 102 PPP patients. Correlations of NFC abnormalities, including nailfold bleeding and enlarged capillaries, with the prevalence of PAO, the incidence of new PAO, and serum levels of cytokines were analyzed.

RESULTS

Detailed examination revealed that of 102 PPP patients, 52 without PAO and 50 with PAO. Both nailfold bleeding and enlarged capillaries were significantly more frequent in patients with PAO (50.0% vs 92.0%, P < .0001; 50.0% vs 94.0%, P < .0001). In addition, PPP patients without PAO were prospectively observed before they developed PAO (mean 28 months [1-52 months]). Multivariate analysis suggested that these NFC abnormalities were predictors of PAO development (hazard ratio 3.37, 95% confidence interval 1.13-10.07; 3.37, 1.13-10.07) and guselkumab prevent PAO development (0.093, 0.012-0.76). The degree of NFC abnormalities correlated with the severity of PAO and serum cytokine levels.

LIMITATIONS

All participants were Japanese.

CONCLUSION

NFC abnormalities could be predictors of PAO in PPP patients, and their degree indicators of disease severity.

The optimal use of tildrakizumab in the elderly via improvement of Treg function and its preventive effect of psoriatic arthritis

Introduction

As a form of precision medicine, this study aimed to investigate the specific patient population that would derive the greatest benefit from tildrakizumab, as well as the mechanism of action and efficacy of tildrakizumab in reducing the occurrence of psoriatic arthritis (PsA).

Methods

To achieve this, a multi-center, prospective cohort study was conducted, involving a population of 246 psoriasis patients who had not received any systemic therapy or topical finger therapy between January 2020 and April 2023. Two independent clinicians, who were blinded to the study, analyzed nailfold capillary (NFC) abnormalities, such as nailfold bleeding (NFB) and enlarged capillaries, as well as the incidence of new PsA. Additionally, the factors that determined the response of psoriasis after seven months of tildrakizumab treatment were examined. The study also examined the quantity and role of regulatory T cells (Tregs) and T helper 17 cells both pre- and post-treatment.

Results

The severity of psoriasis, as measured by the Psoriasis Area and Severity Index (PASI), was found to be more pronounced in the tildrakizumab group (n=20) in comparison to the topical group (n=226). At 7 months after tildrakizumab treatment, multivariate analysis showed that those 65 years and older had a significantly better response to treatment in those achieved PASI clear or PASI 2 or less (Likelihood ratio (LR) 16.15, p<0.0001; LR 6. 16, p=0.01). Tildrakizumab improved the number and function of Tregs, which had been reduced by aging. Tildrakizumab demonstrated significant efficacy in improving various pathological factors associated with PsA. These factors include the reduction of NFB, enlargement of capillaries, and inhibition of PsA progression. The hazard ratio for progression to PsA was found to be 0.06 (95% confidence interval: 0.0007-0.46, p=0.007), indicating a substantial reduction in the risk of developing PsA.

Discussion

Tildrakizumab's effectiveness in improving skin lesions can be attributed to its ability to enhance the number and function of Tregs, which are known to decline with age. Furthermore, the drug's positive impact on NFB activity and capillary enlargement, both of which are recognized as risk factors for PsA, further contribute to its inhibitory effect on PsA progression.

Application of single-cell RNA sequencing methods to develop B cell targeted treatments for autoimmunity

The COVID-19 pandemic coincided with several transformative advances in single-cell analysis. These new methods along with decades of research and trials with antibody therapeutics and RNA based technologies allowed for highly effective vaccines and treatments to be produced at astonishing speeds. While these tools were initially focused on models of infection, they also show promise in an autoimmune setting. Self-reactive B cells play important roles as antigen-presenting cells and cytokine and autoantibody producers for many autoimmune diseases. Yet, current therapies to target autoreactive B cells deplete all B cells irrespective of their pathogenicity. Development of self-reactive B cell targeting therapies that would spare non-pathogenic B cells are needed to treat disease while allowing effective immune responses to other ailments. Single-cell RNA sequencing (scRNA-seq) approaches will aid in identification of the pathogenic self-reactive B cells operative in autoimmunity and help with development of more favorable precision targeted therapies.

Anti-topoisomerase, but not anti-centromere B cell responses in systemic sclerosis display active, Ig-secreting cells associated with lung fibrosis

OBJECTIVES

Almost all patients with systemic sclerosis (SSc) harbour autoantibodies. Anti-topoisomerase antibodies (ATA) and anti-centromere antibodies (ACA) are most prevalent and associate with distinct clinical phenotypes. B cell responses underlying these phenotypes are ill-defined. To understand how B cell autoreactivity and disease pathology connect, we determined phenotypic and functional characteristics of autoreactive B cells in ATA-positive and ACA-positive patients.

METHODS

Levels and isotypes of autoantibodies secreted by ex vivo cultured peripheral blood mononuclear cells from patients with ATA-positive (n=22) and ACA-positive (n=20) SSc were determined. Antibody secreting cells (ASCs) were isolated by cell sorting and cultured separately. Correlations were studied between the degree of spontaneous autoantibody production and the presence and degree of interstitial lung disease (ILD).

RESULTS

Circulating B cells secreting either ATA-immunoglobulin G (IgG) or ACA-IgG on stimulation was readily detectable in patients. The ATA response, but not the ACA response, showed additional secretion of autoreactive IgA. ATA-IgG and ATA-IgA were also secreted spontaneously. Additional cell sorting confirmed the presence of ATA-secreting plasmablasts. The degree of spontaneous ATA-secretion was higher in patients with ILD than in those without (p<0.001) and correlated with the degree of pulmonary fibrosis (p<0.001).

CONCLUSION

In contrast to ACA-positive patients, ATA-positive patients show signs of recent activation of the B cell response that hallmarks this disease. The degree of activation correlates with the presence and severity of ILD, the most deleterious disease manifestation. This could explain differential responsiveness to B cell depleting therapy. The abundant and spontaneous secretion of ATA-IgG and ATA-IgA may point toward a continuously activating trigger.

Impaired Regulation by IL-35 in Systemic Sclerosis

This study investigated the role of IL-35 in systemic sclerosis (SSc) patients, focusing on CD4+ T cell response and immunomodulatory cytokine production. By comparing the cytokine levels in healthy donors (HD) and SSc patients using ELISAs, we found a significantly lower plasma IL-35 concentration in the SSc patients (52.1 ± 5.6 vs. 143 ± 11.1, p < 0.001). Notably, the IL-35 levels showed a negative correlation with TGF-β (p < 0.001) and IL-17 (p = 0.04). Assessing the IL-35R expression across cell types in the SSc patients and HDs via flow cytometry, we found higher levels on monocytes (40.7 + 5.7 vs. 20.3 ± 1.9, p < 0.001) and lower levels on CD8+ T cells (61.8 ± 9.2 vs. 83.4 ± 0.8, p < 0.05) in the SSc patients. The addition of recombinant IL-35 to stimulated peripheral blood mononuclear cells reduced the IL-17+CD4+ T cell percentage (9.0 ± 1.5 vs. 4.8 ± 0.7, p < 0.05) and increased the IL-35+CD4+ T percentage (4.1 ± 2.3 vs. 10.2 ± 0.8, p < 0.001). In a Treg:Tresponder cell Sco-culture assay with HD and SSc samples, rIL35 decreased the cell proliferation and levels of IL-17A (178.2 ± 30.5 pg/mL vs. 37.4 ± 6.4 pg/mL, p < 0.001) and TGF-β (4194 ± 777 pg/mL vs. 2413 ± 608 pg/mL, p < 0.01). Furthermore, we observed a positive correlation between the modified Rodnan skin score (mRSS) and TGF-β (p < 0.001), while there was a negative correlation between mRSS and IL-35 (p = 0.004). Interestingly, higher levels of plasmatic IL-35 were detected in individuals with limited disease compared to those with diffuse disease (60.1 ± 8.0 vs. 832.3 ± 4.1, p < 0.05). These findings suggest that IL-35 exhibits anti-inflammatory properties in SSc and it may serve as a marker for disease severity and a therapeutic target.

The Impact of Nigella sativa Essential Oil on T Cells in Women with Hashimoto's Thyroiditis

BACKGROUND

Hashimoto's thyroiditis (HT) is an autoimmune disease mediated by T cells. It is characterized by the presence of thyroid autoantibodies in the serum, such as anti-thyroid peroxidase antibodies (TPO-Ab) and anti-thyroglobulin antibodies (TG-Ab). The essential oil extracted from Nigella sativa seeds is rich in bioactive substances, such as thymoquinone and cymene.

METHODS

Therefore, we examined the effect of essential oil from Nigella sativa (NSEO) on T cells from HT patients, especially their proliferation capacity, ability to produce cytokines, and susceptibility to apoptosis.

RESULTS

The lowest ethanol (EtOH) dilution (1:10) of NSEO significantly inhibited the proliferation of CD4⁺ and CD8⁺ T cells from HT patients and healthy women by affecting the percentage of dividing cells and the number of cell divisions. In addition, 1:10 and 1:50 NSEO dilutions induced cell death. Different dilutions of NSEO also reduced the concentration of IL-17A and IL-10. In healthy women, the level of IL-4 and IL-2 significantly increased in the presence of 1:10 and 1:50 NSEO dilutions. NSEO did not influence the concentration of IL-6 and IFN-γ.

CONCLUSIONS

Our study demonstrates that NSEO has a strong immunomodulatory effect on the lymphocytes of HT patients.

Umbilical-Cord-Derived Mesenchymal Stromal Cells Modulate 26 Out of 41 T Cell Subsets from Systemic Sclerosis Patients

Systemic sclerosis (SSc) is an immune-mediated disease wherein T cells are particularly implicated, presenting a poor prognosis and limited therapeutic options. Thus, mesenchymal-stem/stromal-cell (MSC)-based therapies can be of great benefit to SSc patients given their immunomodulatory, anti-fibrotic, and pro-angiogenic potential, which is associated with low toxicity. In this study, peripheral blood mononuclear cells from healthy individuals (HC, n = 6) and SSc patients (n = 9) were co-cultured with MSCs in order to assess how MSCs affected the activation and polarization of 58 different T cell subsets, including Th1, Th17, and Treg. It was found that MSCs downregulated the activation of 26 out of the 41 T cell subsets identified within CD4⁺, CD8⁺, CD4⁺CD8⁺, CD4^-CD8^-, and γδ T cells in SSc patients (HC: 29/42) and affected the polarization of 13 out of 58 T cell subsets in SSc patients (HC: 22/64). Interestingly, SSc patients displayed some T cell subsets with an increased activation status and MSCs were able to downregulate all of them. This study provides a wide-ranging perspective of how MSCs affect T cells, including minor subsets. The ability to inhibit the activation and modulate the polarization of several T cell subsets, including those implicated in SSc's pathogenesis, further supports the potential of MSC-based therapies to regulate T cells in a disease whose onset/development may be due to immune system's malfunction.

Long-term Outcomes After Rituximab Treatment for Patients With Systemic Sclerosis: Follow-up of the DESIRES Trial With a Focus on Serum Immunoglobulin Levels

Importance

Rituximab is emerging as a promising therapeutic option for systemic sclerosis (SSc), but its long-term outcomes and response markers are unknown.

Objective

To evaluate the long-term outcomes after rituximab treatment for SSc and identify potential response markers.

Design, Setting, and Participants

In this single-center cohort study, patients with SSc who continued to receive rituximab after the DESIRES trial were analyzed with a median follow-up of 96 weeks. Among the 43 patients who completed the DESIRES trial, 31 continued to receive rituximab, of which 29 with complete data were included in this study.

Exposures

Rituximab treatment.

Main Outcomes and Measures

A post hoc analysis of the clinical and laboratory data.

Results

In 29 patients with SSc (27 female [93%]; median [IQR] age, 48 [35-45] years), significant improvement in modified Rodnan skin score (MRSS) and percentage of predicted forced vital capacity (FVC%) were observed after 1 (median [IQR] change in MRSS, -7 [-8.5 to -4]; P < .001) and 3 (median [IQR] change in FVC% predicted, 1.85 [0.13-5.68]; P < .001) courses of rituximab, respectively, both of which were sustained during follow-up. High responders (MRSS improvement of ≥9; n = 16) experienced a greater decrease in serum levels of IgG (median [IQR] change in IgG, -125 [-207 to -83] vs 7 [-120 to 43]; P = .008) and IgA (median [IQR] change in IgA, -45 [-96 to -32] vs -11 [-20 to 3]; P < .001) compared with low responders (MRSS improvement of ≤8; n = 13). In particular, decrease in serum IgA levels significantly correlated with the improvement in MRSS (r = 0.64; P < .001). At the last follow-up, low IgM, low IgA, and low IgG was observed in 7, 1, and 1 patient, respectively, of which low IgM was associated with greater improvement in FVC% predicted (median [IQR] change in FVC% predicted, 7.2 [3.8-8.9] vs 3.6 [1.4-6.2]; P = .003).

Conclusions and Relevance

In this cohort study, rituximab treatment was associated with significantly improved skin and lung fibrosis in SSc in a long-term follow-up. Decrease in serum immunoglobulins was associated with greater clinical response.

Autoreactive B cell responses targeting nuclear antigens in systemic sclerosis: Implications for disease pathogenesis

A hallmark of disease pathogenesis of systemic sclerosis (SSc) is the presence of autoreactive B cell responses targeting nuclear proteins. Almost all SSc-patients harbour circulating antinuclear autoantibodies of which anti-topoisomerase 1, anti-centromere protein, anti-RNA polymerase III and anti-fibrillarin autoantibodies (ATA, ACA, ARA and AFA, respectively) are the most common and specific for SSc. In clinical practice, autoantibodies serve as diagnostic biomarkers and can aid in the identification of clinical phenotypes of the disease. However, factors driving disease progression in SSc are still poorly understood, and it is difficult to predict disease trajectories in individual patients. Moreover, treatment decisions remain rather empirical, with variable response rates in clinical trials due to patient heterogeneity. Current evidence has indicated that certain patients may benefit from B cell targeting therapies. Hence, it is important to understand the contribution of the antinuclear autoantibodies and their underlying B cell response to the disease pathogenesis of SSc.

The Role of T Cells in Systemic Sclerosis: An Update

Systemic sclerosis (SSc) is a chronic disease characterized by microvasculopathy, autoantibodies (autoAbs), and fibrosis. The pathogenesis of the disease is incompletely understood. Microvasculopathy and autoAbs appear very early in the disease process. AutoAbs, such as those directed against DNA topoisomerase I (Topo I), are disease specific and associated with disease manifestations, and indicate activation of the adaptive immune system. B cells are involved in fibrosis in SSc. T cells are also involved in disease pathogenesis. T cells show signs of antigen-induced activation; T cells of TH2 type are increased and produce profibrotic cytokines interleukin (IL)-4, IL-13, and IL-31; CD4+ cytotoxic T lymphocytes are increased in skin lesions, and cause fibrosis and endothelial cell apoptosis; circulating T follicular helper (TFH) cells are increased in SSc produce IL-21 and promote plasmablast antibody production. On the other hand, regulatory T cells are impaired in SSc. These findings provide strong circumstantial evidence for T cell implication in SSc pathogenesis and encourage new T cell-directed therapeutic strategies for the disease.

Safety and efficacy of rituximab in systemic sclerosis (DESIRES): open-label extension of a double-blind, investigators-initiated, randomised, placebo-controlled trial

BACKGROUND

Results from the double-blind phase 2 DESIRES trial showed that rituximab improves skin thickening in systemic sclerosis. Here, we present the findings of a subsequent 24-week open-label extension phase.

METHODS

Patients with systemic sclerosis aged 20-79 years, who fulfilled the 2013 American College of Rheumatology and European League Against Rheumatism classification criteria, with a baseline modified Rodnan Skin Score (mRSS) of 10 or greater were enrolled into the DESIRES trial, which was an investigator-initiated, phase 2, double-blind, randomised controlled trial of rituximab versus placebo conducted at four sites in Japan. After completion of 24 weeks of treatment with either rituximab or placebo, patients in both groups received a further 24 weeks of rituximab (375 mg/m2 intravenously, once per week for 4 consecutive weeks) in an open-label extension. The primary endpoint of the double-blind trial was mRSS at week 24, which was reassessed at week 48 in the open-label extension. All endpoints were exploratory. Safety analyses included all participants who received at least one dose of study drug; efficacy analyses included those who had received at least one dose and undergone efficacy assessment at 24 weeks in the double-blind phase and at 48 weeks in the extension phase. The DESIRES study is registered with ClinicalTrials.gov, NCT04274257, and UMIN-CTR, UMIN000030139.

FINDINGS

Between Nov 28, 2017, and Nov 6, 2018, 56 patients were randomly assigned to either rituximab (n=28) or placebo (n=28) in a double-blind study. 26 patients initially assigned to rituximab and 20 assigned to placebo transitioned to the open-label extension and all received at least one dose of rituximab; 24 participants in the rituximab-rituximab group and 19 in the placebo-rituximab group completed the extension phase. In the rituximab-rituximab group, there was an improvement in mRSS from baseline at week 24 (-5·81 [SD 3·16]), with further improvement at week 48 (-8·88 [3·10]). In the placebo-rituximab group, mRSS worsened at week 24 (2·14 [SD 5·51]) but improved at the week 48 assessment (-6·05 [4·43]). One patient each in the rituximab-rituximab and placebo-rituximab groups experienced one serious adverse event during the open-label phase (cholangitis and pneumococcal pneumonia, respectively). There were no deaths during follow-up.

INTERPRETATION

Two courses of rituximab is a safe treatment that can provide sustained improvement in systemic sclerosis for at least 48 weeks.

FUNDING

Japan Agency for Medical Research and Development.

TRANSLATION

For the Japanese translation of the abstract see Supplementary Materials section.

Involvement of B cells in the development of systemic sclerosis

Systemic sclerosis (SSc) is a rare intractable systemic disease that causes fibrosis and vasculopathy against a background of autoimmune abnormalities. Although the etiology is not yet fully understood, the type of autoantibodies detected in SSc is closely associated with disease severity and prognosis, supporting that those autoimmune abnormalities play an important role in the pathogenesis of SSc. Although the direct pathogenicity of autoantibodies found in SSc is unknown, many previous studies have shown that B cells are involved in the development of SSc through a variety of functions. Furthermore, a number of clinical studies have been conducted in which B-cell depletion therapy has been tried for SSc, and many of these studies have found B-cell depletion therapy to be effective for SSc. However, the involvement of B cells in pathogenesis is complex, as they not only promote inflammation but also play an inhibitory role. This article outlines the role of B cells in the development of SSc, including the latest research.

Involvement of Molecular Mechanisms between T/B Cells and IL-23: From Palmoplantar Pustulosis to Autoimmune Diseases

Palmoplantar pustulosis (PPP) is a disease that causes recurrent blisters and aseptic pustules on the palms and soles. It has been suggested that both innate and acquired immunity are involved. In particular, based on the tonsils and basic experiments, it has been assumed that T and B cells are involved in its pathogenesis. In addition, the results of clinical trials have suggested that IL-23 is closely related to the pathogenesis. This review describes PPP and the genetic background, the factors involved in the onset and exacerbation of disease and its relation to the molecular mechanism. In addition, we describe the usefulness of biological therapy and its implications in relation to the importance in pathology, the pathogenesis of PPP, the importance of the role of the IL-23-Th17 axis and IL-36 in PPP. Furthermore, we describe an animal experimental model of PPP, the efficacy and mechanism of action of guselkumab, an anti-IL-23 antibody, the latest research, and finally the possibility for it to be effective for other autoimmune diseases.

Autoantibodies in systemic lupus erythematosus: From immunopathology to therapeutic target

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by multiple organ inflammatory damage and wide spectrum of autoantibodies. The autoantibodies, especially anti-dsDNA and anti-Sm autoantibodies are highly specific to SLE, and participate in the immune complex formation and inflammatory damage on multiple end-organs such as kidney, skin, and central nervous system (CNS). However, the underlying mechanisms of autoantibody-induced tissue damage and systemic inflammation are still not fully understood. Single cell analysis of autoreactive B cells and monoclonal antibody screening from patients with active SLE has improved our understanding on the origin of autoreactive B cells and the antigen targets of the pathogenic autoantibodies. B cell depletion therapies have been widely studied in the clinics, but the development of more specific therapies against the pathogenic B cell subset and autoantibodies with improved efficacy and safety still remain a big challenge. A more comprehensive autoantibody profiling combined with functional characterization of autoantibodies in diseases development will shed new insights on the etiology and pathogenesis of SLE and guide a specific treatment to individual SLE patients.

The Role of B Cells in Scleroderma Lung Disease Pathogenesis

Systemic sclerosis (SSc) is a chronic, autoimmune, multisystem disease characterized by tissue fibrosis that, apart from the skin, may affect the lungs among other organs. B cells have been found in tissue lymphocytic infiltrates; in the lungs are encountered in lymphoid aggregates. The abnormal and hyperreactive B cell in SSc may initiate and perpetuate the fibrotic process via incompletely understood mechanisms. Studies in animal models of SSc have demonstrated that B cell dysregulation is an early event in disease pathogenesis. Functional disturbances of BCR signaling such as decreased inhibitory CD22 signal transduction or augmented CD19-mediated signaling result in prolonged B cell activation. Antagonism of BAFF, a cytokine known for his central role in B cell survival and maturation, not only suppresses the production of fibrogenic cytokines such as IL-6 and IL-10, but also amplifies antifibrogenic cytokine secretion such as IFN-γ and it finally contributes to skin fibrosis attenuation. B cells subsets in SSc patients display several abnormalities. Naïve B cells are increased, in contrast to switched memory B cells that are not only decreased but also activated. Disturbances in the expression of molecules that are involved in B cell tuning have also been described. Interestingly, a distinct B cell population characterized by anergy and exhaustion has been found to be increased in patients with SSc-ILD. Another B cell subset, the CD30+GM-Beff, is capable to differentiate monocytes to dendritic cells and is increased in SSc patients with ILD. Of note, patients with SSc-ILD exhibit increased expression of the inhibitory receptor FcγRIIB on naïve and double negative B cells aiming perhaps to counterbalance the abnormal B cell activation. Studies of B cell targeted treatments have demonstrated promising clinical efficacy. Therefore, B cell eliminating therapies could be integrated into the therapeutic armamentarium of patients suffering from SSc-ILD aiming to at least stabilize the fibrotic lung process.

Can Antinuclear Antibodies Have a Pathogenic Role in Systemic Sclerosis?

Systemic sclerosis (SSc) is a connective tissue disease characterized by extensive fibrosis of the skin and internal organs, associated with vasculopathy and autoimmune features. Antinuclear antibodies (ANA) are found in almost all SSc patients and constitute strong diagnosis and prognosis biomarkers. However, it remains unclear whether ANA are simple bystanders or if they can have a role in the pathophysiology of the disease. One might think that the nuclear nature of their targets prevents any accessibility to autoantibodies. Nevertheless, recent data suggest that ANA could be pathogenic or at least contribute to the perennation of the disease. We review here first the indirect clues of the contribution of ANA to SSc: they are associated to the disease subtypes, they may precede disease onset, their titer correlates with disease activity and severity, there is an association between molecular subsets, and some patients can respond to B-cell targeting therapy. Then, we describe in a second part the mechanisms of ANA production in SSc from individual genetic background to post-transcriptional modifications of neoantigens. Finally, we elaborate on the potential mechanisms of pathogenicity: ANA could be pathogenic through immune-complex-mediated mechanisms; other processes potentially involve molecular mimicry and ANA penetration into the target cell, with a focus on anti-topoisomerase-I antibodies, which are the most probable candidate to play a role in the pathophysiology of SSc. Finally, we outline some technical and conceptual ways to improve our understanding in this field.

Cytokine-producing B-cell balance associates with skin fibrosis in patients with systemic sclerosis

Systemic sclerosis (SSc) is an autoimmune disease characterized by skin and lung fibrosis. Over 90% of patients with SSc are positive for autoantibodies. In addition, the serum levels of B-cell activating factor, a potent B-cell stimulator, are correlated with SSc severity and activity. Thus, B cells play an important role in SSc pathogenesis. However, two opposing B-cell subsets exist: effector B cells (Beff) and regulatory B cells (Breg). Interleukin (IL)-6-producing Beff have been shown to promote scleroderma in a mouse model, whereas IL-10-producing Breg inhibit scleroderma development. In the present study, we investigated the clinical association of effector and regulatory B cells in patients with SSc. The blood levels of IL-6-producing Beff and IL-10-producing Breg were measured in 30 patients with SSc and 21 healthy subjects by flow cytometry. The frequency of IL-6-producing Beff in the blood was significantly (p < 0.0001) elevated in patients with SSc (median, 56.2%; range, 35.3-81.3%) compared with that in healthy controls (median, 41.3%; range, 21.0-61.3%). In contrast, the frequency of IL-10-producing Breg in the blood was significantly (p < 0.05) decreased in patients with SSc (median, 1.4%; range, 0.5-2.8%) compared with that in healthy controls (median, 2.0%; range, 1.1-3.8%). The Beff/Breg ratio was significantly increased in patients with SSc. In addition, the Beff/Breg ratio was positively correlated with the skin score and extent of interstitial lung disease. These results suggest that dysregulation of effector and regulatory B-cell balance contributes to SSc pathogenesis.

Pathogenetic Aspects of Systemic Sclerosis: A View Through the Prism of B Cells

Systemic sclerosis (SSc) is a rare fibrotic rheumatic disease, associated with psychological distress and increased morbidity and mortality due to skin involvement and internal organ damage. The current understanding of the complex pathogenesis is yet incomplete and disease therapeutic algorithms are far from optimal. Immunologic aberrations are considered key factors for the disease, along with vascular involvement and excess fibrosis. Adaptive immunity and its specialized responses are an attractive research target and both T and B cells have been extensively studied in recent years. In the present review, the focus is placed on B cells in SSc. B cell homeostasis is deranged and B cell subsets exhibit an activated phenotype and abnormal receptor signaling. Autoantibodies are a hallmark of the disease and the current perception of their diagnostic and pathogenetic role is analyzed. In addition, B cell cytokine release and its effect on immunity and fibrosis are examined, together with B cell tissue infiltration of the skin and lung. These data support the concept of targeting B cells as part of the therapeutic plan for SSc through well designed clinical trials.

Pharmacotherapy of Itch-Antihistamines and Histamine Receptors as G Protein-Coupled Receptors

Itching can decrease quality of life and exacerbate skin symptoms due to scratching. Itching not only contributes to disease progression but also triggers complications such as skin infections and eye symptoms. Therefore, controlling itching is very important in therapeutic management. In addition to the well-known histamine, IL-31, IL-4 and IL-13 have recently been reported as factors that induce itching. Itching may also be caused by factors other than these histamines. However, we do not know the extent to which these factors are involved in each disease. In addition, the degree of involvement is likely to vary among individuals. To date, antihistamines have been widely used to treat itching and are often effective, suggesting that histamine is more or less involved in itchy diseases. This review discusses the ligand-receptor perspective and describes the dynamics of G protein-coupled receptors, their role as biased agonists, their role as inverse agonists, proactive antihistamine therapy, and drug selection with consideration of impaired performance and anti-PAF effects.