Distinctive association of peripheral immune cell phenotypes with capillaroscopic microvascular patterns in systemic sclerosis

Evolution of diagnostic criteria and new insights into clinical testing in mixed connective tissue disease; anti-survival motor neuron complex antibody as a novel marker of severity of the disease

Mixed connective tissue disease (MCTD) is an autoimmune disorder characterized by a combination of clinical features from systemic lupus erythematosus, systemic sclerosis, and inflammatory muscle disease, along with the presence of positive anti-U1-ribonucleoprotein (U1-RNP) antibodies. The exact etiology of the disease remains unclear, but it is believed to involve vascular damage within the context of heightened autoimmune responses. Consequently, Raynaud's phenomenon and pulmonary arterial hypertension are observed in patients with MCTD. While specific biomarkers for MCTD have not yet been identified, the recent study of the utility of anti-survival motor neuron complex (SMN) antibodies in MCTD suggests a promising avenue for further research and the accumulation of additional evidence.

Perspective to precision medicine in scleroderma

Systemic sclerosis (SSc) is a rare and heterogeneous disease with no relevant environmental trigger or significant responsible gene. It has been and will continue to be difficult to identify large enough patients to conduct classic population-based epidemiologic exposure/non-exposure studies with adequate power to ascertain environmental and genetic risk factors for these entities. The complexity of pathogenesis and heterogeneity are likely to require personalized/precision medicine for SSc. Since several potential drugs are currently available for specific patients if not whole SSc, classification of SSc seems to form the foundation for a better therapeutic strategy. To date, SSc has been classified based on the extent/severity of the affected area as well as some disease markers, including the autoantibody profile. However, such an analysis should also lead to improvements in the design of appropriately stratified clinical trials to determine the effects and prediction of targeted therapies. An approach based on drug response preclinically conducted using patients' own fibroblasts in vitro, can provide a precise disease marker/therapeutic selection for clinical practice. Because scleroderma dermal fibroblasts have a persistent hyper-productive phenotype occurring not only in person, but also in cell culture conditions. Thus, an accumulating approach based on disease markers ensures progression and de-escalation to re-establish a better life with a personally optimized drug environment after the onset of SSc.

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.

T follicular helper cells in autoimmune diseases

T follicular helper (Tfh) cells with the phenotype of mainly expressing surface molecules C-X-C motif chemokine receptor type 5 (CXCR5), inducible co-stimulator (ICOS), secreting cytokine interleukin-21 (IL-21) and requiring the transcription factor B cell lymphoma 6 (BCL-6) have been recently defined as a new subset of CD4⁺ T cells. They exist in germinal centers (GCs) of lymphoid organs and in peripheral blood. With the ability to promote B cell development, GC formation and antibody production, Tfh cells play critical roles in the pathogenesis of many autoimmune diseases, such as systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), primary Sjögren's syndrome (pSS), etc. The aberrant proliferation and function of Tfh cells will cause the pathological process like autoantibody production and tissue injury. In this paper, we review the recent advances in Tfh cell biology and their roles in autoimmune diseases, with a mention of their use as therapeutic targets, which will shed more light on the pathogenesis and treatment of certain autoimmune diseases.

Nailfold microvascular abnormalities are associated with a higher prevalence of pulmonary arterial hypertension in patients with MCTD

OBJECTIVE

MCTD manifests with microvasculopathy and overlapping clinical features of SLE, SSc and idiopathic inflammatory myopathies (IIM). The aim of this study was to investigate the clinical significance of microvasculopathy in patients with MCTD using nailfold videocapillaroscopy (NVC).

METHODS

Fifty patients with newly diagnosed and untreated MCTD were enrolled in this multicentre, prospective and observational study. Clinical features and NVC findings were assessed at baseline and after 1 year post-intervention, along with disease controls [SLE (n = 40), SSc (n = 70) and IIM (n = 50)].

RESULTS

All MCTD patients presented Raynaud's phenomenon and were positive for anti-U1 RNP antibodies, and 22.0% (11/50) had pulmonary arterial hypertension (PAH). The prevalence of NVC scleroderma patterns in MCTD was 38.0%, which was lower than SSc (88.6%) but higher than SLE (10.0%). In addition, when we divided MCTD patients into two groups by presence or absence of NVC scleroderma patterns, we found a higher prevalence of PAH in patients with NVC scleroderma patterns. Namely, NVC scleroderma patterns were observed in all MCTD patients with PAH, and in 21.0% of those without PAH. After intensive immunosuppressive therapy, NVC scleroderma patterns disappeared in half of the MCTD patients but were not changed in SSc patients.

CONCLUSIONS

MCTD differed from SLE, SSc and IIM in terms of the prevalence and responsiveness of NVC scleroderma patterns to immunosuppressive therapy. Detection of nailfold microvascular abnormalities in MCTD could contribute to predicting PAH and help us to understand further aspects of the pathogenesis of MCTD.

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.

Insights into molecular and clinical characteristics of very early systemic sclerosis

PURPOSE OF REVIEW

The early heterogenous presentation of systemic sclerosis (SSc), in particular without skin involvement, has been a confounding factor delaying early diagnosis. In fact, early signs of SSc as Raynaud's phenomenon and puffy fingers, are also typical of other connective tissue diseases (CTDs) such as mixed CTD and undifferentiated CTD. In the last decade, a significant effort has been dedicated in defining molecular characteristics that could be used as early SSc biomarkers. In this narrative review, we address the present situation where several clinical scenarios are in search of a correct positioning into the prescleroderma (pre-SSc) phase as well as in the very early phase of SSc.

RECENT FINDINGS

Literature data showed that a part of patients classified as sine scleroderma SSc (ssSSc), mixed CTD and undifferentiated CTD may already belong to the very early phase of SSc, thus having a different pattern of progression to SSc. Recently, the very early diagnosis of systemic sclerosis (VEDOSS) criteria has been validated.

SUMMARY

while the area of pre-SSc still remains fuzzy, the VEDOSS study has shown that a 'window of opportunity' does exist also for SSc. In the very next future, this may allow to start the treatment to prevent the disease progression to a more advanced fibrotic stage.

Toward Molecular Stratification and Precision Medicine in Systemic Sclerosis

Systemic sclerosis (SSc), a complex multi-systemic disease characterized by immune dysregulation, vasculopathy and fibrosis, is associated with high mortality. Its pathogenesis is only partially understood. The heterogenous pathological processes that define SSc and its stages present a challenge to targeting appropriate treatment, with differing treatment outcomes of SSc patients despite similar initial clinical presentations. Timing of the appropriate treatments targeted at the underlying disease process is critical. For example, immunomodulatory treatments may be used for patients in a predominantly inflammatory phase, anti-fibrotic treatments for those in the fibrotic phase, or combination therapies for those in the fibro-inflammatory phase. In advancing personalized care through precision medicine, groups of patients with similar disease characteristics and shared pathological processes may be identified through molecular stratification. This would improve current clinical sub-setting systems and guide personalization of therapies. In this review, we will provide updates in SSc clinical and molecular stratification in relation to patient outcomes and treatment responses. Promises of molecular stratification through advances in high-dimensional tools, including omic-based stratification (transcriptomics, genomics, epigenomics, proteomics, cytomics, microbiomics) and machine learning will be discussed. Innovative and more granular stratification systems that integrate molecular characteristics to clinical phenotypes would potentially improve therapeutic approaches through personalized medicine and lead to better patient outcomes.

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.

The Pathophysiological Roles of Regulatory T Cells in the Early Phase of Systemic Sclerosis

Systemic sclerosis (SSc) is an autoimmune disease that is characterized by vascular damage and fibrosis. Both clinical manifestations and immunological disturbances are diverse according to the disease duration. Particularly, changes in immunological processes are prominent in the early phase of SSc. The orchestration of several subsets of immune cells promotes autoimmune responses and inflammation, and eventually stimulates pro-fibrotic processes. Many reports have indicated that CD4⁺ T cells play pivotal roles in pathogenesis in the early phase of SSc. In particular, the pathogenic roles of regulatory T (Treg) cells have been investigated. Although the results were controversial, recent reports suggested an increase of Treg cells in the early phase of SSc patients. Treg cells secrete transforming growth factor-β (TGF-β), which promotes myofibroblast activation and fibrosis. In addition, the dysfunction of Treg cells in the early phase of SSc was reported, which results in the development of autoimmunity and inflammation. Notably, Treg cells have the plasticity to convert to T-helper17 (Th17) cells under pro-inflammatory conditions. Th17 cells secrete IL-17A, which could also promote myofibroblast transformation and fibrosis and contributes to vasculopathy, although the issue is still controversial. Our recent transcriptomic comparison between the early and late phases of SSc revealed a clear difference of gene expression patterns only in Treg cells. The gene signature of an activated Treg cell subpopulation was expanded in the early phase of SSc and the oxidative phosphorylation pathway was enhanced, which can promote Th17 differentiation. And this result was accompanied by the increase in Th17 cells frequency. Therefore, an imbalance between Treg and Th17 cells could also have an important role in the pathogenesis of the early phase of SSc. In this review, we outlined the roles of Treg cells in the early phase of SSc, summarizing the data of both human and mouse models. The contributions of Treg cells to autoimmunity, vasculopathy, and fibrosis were revealed, based on the dysfunction and imbalance of Treg cells. We also referred to the potential development in treatment strategies in SSc.

Eosinophilic granulomatosis with polyangiitis exhibits T cell activation and IgG4 immune response in the tissue; comparison with IgG4-related disease

Objective

To study the pathophysiological differences of EGPA and IgG₄-related disease (RD) by clarifying their clinical, pathological and immunological features.

Methods

Clinical and pathological findings were compared in patients with EGPA and IgG₄-RD. Peripheral blood mononuclear cells were used for comprehensive flow cytometric analysis.

Results

An elevation of the IgG4 level was found in all EGPA cases, with the accompanying pathological findings of lymphocytic infiltration and fibrosis observed in 30.8% patients, and the elevation of IgG₄/IgG ratio in 61.5% patients. However, actual IgG₄ levels, as well as the degree of the infiltration of IgG₄-positive plasma cells, were still higher in patients with IgG₄-RD than patients with EGPA. Examination by ACR/EULAR classification criteria showed only 13.6% of the EGPA patients met entry criteria, while all of them met the exclusion criteria. In regard to the immunophenotyping, EGPA patients had increases in activated CD4 and CD8 T cells compared with the healthy controls. However, no such similar changes occurred in IgG₄-RD patients. On the other hand, both the EGPA and IgG₄-RD patient groups had correlated increased plasmablasts and Tfh. These results indicate the presence of two axes: namely, the activation of T cells and that of B cells. Both axes are present in EGPA, but the T cell activation axis was not observed in IgG₄-RD.

Conclusions

The elevation of serum IgG₄ as well as pathological IgG₄ infiltration are not specific. Meanwhile, EGPA and IgG4-RD differ in immunological phenotypes, indicating the possible importance of the predominant activation of T cells in the development of vasculitis.

Contributions of Immune Cells and Stromal Cells to the Pathogenesis of Systemic Sclerosis: Recent Insights

Systemic sclerosis (SSc) is a multisystem rheumatic disease characterized by vascular dysfunction, autoimmune abnormalities, and progressive organ fibrosis. A series of studies in SSc patients and fibrotic models suggest that immune cells, fibroblasts, and endothelial cells participate in inflammation and aberrant tissue repair. Furthermore, the growing number of studies on single-cell RNA sequencing (scRNA-seq) technology in SSc elaborate on the transcriptomics and heterogeneities of these cell subsets significantly. In this review, we summarize the current knowledge regarding immune cells and stromal cells in SSc patients and discuss their potential roles in SSc pathogenesis, focusing on recent advances in the new subtypes by scRNA-seq.

TFH cells in systemic sclerosis

Systemic sclerosis is an autoimmune disease characterized by excessive dermal fibrosis with progression to internal organs, vascular impairment and immune dysregulation evidenced by the infiltration of inflammatory cells in affected tissues and the production of auto antibodies. While the pathogenesis remains unclear, several data highlight that T and B cells deregulation is implicated in the disease pathogenesis. Over the last decade, aberrant responses of circulating T follicular helper cells, a subset of CD4 T cells which are able to localise predominantly in the B cell follicles through a high level of chemokine receptor CXCR5 expression are described in pathogenesis of several autoimmune diseases and chronic graft-versus-host-disease. In the present review, we summarized the observed alteration of number and frequency of circulating T follicular helper cells in systemic sclerosis. We described their role in aberrant B cell activation and differentiation though interleukine-21 secretion. We also clarified T follicular helper-like cells involvement in fibrogenesis in both human and mouse model. Finally, because T follicular helper cells are involved in both fibrosis and autoimmune abnormalities in systemic sclerosis patients, we presented the different strategies could be used to target T follicular helper cells in systemic sclerosis, the therapeutic trials currently being carried out and the future perspectives from other auto-immune diseases and graft-versus-host-disease models.

Increased Frequency of Activated Switched Memory B Cells and Its Association With the Presence of Pulmonary Fibrosis in Diffuse Cutaneous Systemic Sclerosis Patients

Disease-associated, high-affinity pathological autoantibody production is a well-described consequence of immune dysregulation affecting B cells in systemic sclerosis (SSc), including the distribution of B-cell subsets. We have previously shown that the increased relative frequency of CD19+CD27+IgD- switched memory B cells is associated with the severe form of SSc. This study sought to analyze memory B cell subsets using an extended range of markers for further subdivision based on CD19, IgD, CD27, CD38 and CD95 phenotype, to define relationship between the alterations of memory B cell subsets and the clinical features of SSc. Peripheral blood samples were obtained from 21 SSc patients, including 14 diffuse (dcSSc) and 7 limited (lcSSc) cutaneous SSc patients, with disease duration of 2.7 ( ± 1.6) years. After purification of CD19+ B cells, multiparametric flow cytometry was performed and the frequencies of CD19+IgD-CD27-CD38+ double negative (DN) 1, CD19+IgDloCD27+CD38+ unswitched, CD19+IgD-CD27+CD38+CD95- resting switched and CD19+IgD-CD27+CD38-CD95+ activated switched memory (ASM) B cells were determined, and correlated with clinical features of SSc. The dcSSc patients had a higher frequency of ASM B cells (p = 0.028) compared to lcSSc patients. The percentage of ASM B cells was elevated in anti-Scl-70 (anti-topoisomerase I) antibody positive patients compared to negative patients (p = 0.016). Additionally, the frequency of ASM B cells was also increased in patients with pulmonary fibrosis (p = 0.003) suggesting that patients with severe form of SSc have higher ASM B cell ratios. Furthermore, the ratio of DN1 B cells was decreased (p = 0.029), while the level of anti-citrate synthase IgG natural autoantibody was elevated (p = 0.028) in patients with active disease. Our observations on the increase of ASM B cells in dcSSc and in patients with pulmonary fibrosis may point to the association of this alteration with the severe form of the disease. Functionally the correlation of ASM B cells as effector memory-plasma cell precursors with anti-topoisomerase I antibody positivity could reflect their contribution to pathological autoantibody production, whereas the decrease of memory precursor DN B cells and the increase of anti-citrate synthase IgG autoantibody may have potential significance in the assessment of disease activity.

New promising drugs for the treatment of systemic sclerosis: pathogenic considerations, enhanced classifications, and personalized medicine

Introduction: Systemic sclerosis (SSc), also known as scleroderma, is a complex orphan disease characterized by early inflammatory features, vascular hyper-reactivity, and fibrosis of the skin and internal organs. Although substantial progress has been made in the understanding of the pathogenesis of SSc, there is still no disease-modifying drug that could significantly impact the natural history of the disease.Areas covered: This review discusses the rationale, preclinical evidence, first clinical eevidence,and pending issues concerning new promising therapeutic options that are under investigation in SSc. The search strategy was based on PubMed database and clinical trial.gov, highlighting recent key pathogenic aspects and phase I or II trials of investigational drugs in SSc.Expert opinion: The identification of new molecular entities that potentially impact inflammation and fibrosis may constitute promising options for a disease modifying-agent in SSc. The early combinations of antifibrotic drugs (such as pirfenidone) with immunomodulatory agents (such as mycophenolate mofetil) may also participate to achieve such a goal. A more refined stratification of patients, based on clinical features, molecular signatures, and identification of subpopulations with distinct clinical trajectories, may also improve management strategies in the future.

Nailfold videocapillaroscopy: a novel possible surrogate marker for the evaluation of peripheral microangiopathy in pulmonary arterial hypertension

Nailfold videocapillaroscopy (NVC) changes in systemic sclerosis (SSc) are correlated with vascular complications, such as pulmonary arterial hypertension (PAH), supporting a potential link between peripheral and internal organ vasculopathy. The current stage of knowledge regarding NVC and PAH is discussed, focusing on the assessment of peripheral microangiopathy and a potential relationship with functional, echocardiographic, and haemodynamic markers of cardiac dysfunction. A comprehensive literature search was carried out to identify all studies focusing on NVC findings in patients with PAH, diagnosed with right heart catheterization. The majority of the studies examined NVC findings in patients with SSc-PAH, while three studies reported NVC abnormalities in patients with idiopathic PAH. Besides the pulmonary vasculature, a systemic component of microangiopathy seems to be involved in PAH. Well-designed prospective trials are warranted to validate NVC as a biomarker, with clinical implications in the diagnostic evaluation, risk stratification, and overall management of PAH in the daily clinical setting.

The importance of skin manifestations, serology and nailfold (video)capillaroscopy in morphea and systemic sclerosis: current understanding and new insights

Since the field around morphea and systemic sclerosis (SSc) is evolving rapidly, this review approaches conventional as well as more recent clinical developments from a dermatological point of view. Skin manifestations are critical in sub-classifying these diseases ensuring a correct prognosis for these patients. They can be discretely present, and therefore, diagnosis can be challenging sometimes, implicating a thorough dermatological examination is mandatory. Furthermore, a growing amount of dermatologists perform nailfold videocapillaroscopy (NVC), a more recent reliable non-invasive imaging technique used for in vivo assessment of the microcirculation at the nailfold. After all, specific NVC-changes are present in a majority of patients with SSc. This way, dermatologists not only take part in the diagnosis process through clinical investigation but also through the use of a modern state of the art imaging technique that is becoming the golden standard in SSc multidisciplinary workup. In this review, current understandings for NVC in morphea and SSc are revised. So far, the role of NVC in the diagnosis/prognosis/classification of morphea patients has not been thoroughly investigated to make proper conclusions. As for SSc, it is well known that NVC contributes to the diagnosis and can make a fundamental difference especially when obvious clinical SSc signs are absent. This review emphasizes the (somewhat underestimated) role of dermatologists in the process of diagnosis and follow-up, and thus, the difference we can make for our patients and fellow colleagues in the multidisciplinary workup of SSc and morphea.

T follicular helper cell subsets: a potential key player in autoimmunity

Follicular helper T (Tfh) cells are one of CD4+ helper T subsets which promote B cell maturation, activation and antigen-specific antibody production. Autoantibodies are hallmarks of autoimmune diseases, and crucial contributions of Tfh cells in development of these diseases are now evident. Deregulation of Tfh activities can contribute to a pathogenic autoantibody production and can play an important role in the promotion of autoimmune diseases. These days multiple researchers reported three subpopulations which has distinct effector functions in Tfh cells: Tfh1, Tfh2 and Tfh17 cells. In this review, we summarize the observed alterations in whole Tfh cells and subset distribution during autoimmune diseases.

The approach to precision medicine for the treatment of psoriatic arthritis

In rheumatic diseases, advances in biological molecular-targeted therapies have brought remarkable progress in treatment, but the molecular and clinical heterogeneity of the diseases can often pose a treatment challenge. In psoriatic arthritis, each patient exhibits various symptoms, and some may be resistant to treatment. It is difficult to improve all of these various symptoms simultaneously with the use of limited drugs. Therefore, precision medicine is an urgent concern that is required to overcome this problem. However, few studies focus on the precision medicine in rheumatic disease including psoriatic arthritis. We explored the potential of precision medicine in which patients with psoriatic arthritis are stratified by lymphocyte flow cytometry to select specific biologics. Selecting specific biologics according to different immunophenotypes of peripheral blood lymphocytes in psoriatic arthritis was shown to produce high therapeutic responses; in other words, the potential of precision medicine was suggested. The peripheral blood lymphocyte analysis can be applied to many other rheumatic diseases presenting various clinical features, such as spondyloarthritis and systemic lupus erythematous. We should shed light on the precision medicine not only in the psoriatic arthritis also in the other rheumatic disease.