B cells in systemic sclerosis: from pathophysiology to treatment

CAR-T cell therapy in rheumatic diseases: a review article

CAR-T cell therapy, a pioneering immune-modulating treatment that was initially designed for hematologic malignancies, is now being considered a potential treatment for autoimmune and rheumatic diseases. This method involves genetically engineering T cells to express chimeric antigen receptors (CARs), allowing them to target specific antigens associated with pathogenic immune cells. The review covers the possibility of CAR-T therapy in the treatment of autoimmune diseases like systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), systemic sclerosis (SSc). The therapy's ability to maintain remission by targeting autoreactive B cells in the course of disease has been an important aspect of studies involving SLE. In refractory RA, CAR-T cells also demonstrate a potential therapeutic modality in selectively killing immune cells driving the disease process. For SSc, CAR-T therapy may represent a novel therapeutic approach because it targets the dysregulated activity of B cells as well as the fibrotic processes that drive the disease pathology. Emerging evidence suggests potential applications in conditions such as Sjögren's syndrome and dermatomyositis. While CAR-T therapy promises accuracy, persistence, and the potential for long-term remission, many problems remain, including the risk of cytokine release syndrome, immune toxicity, and treatment affordability. The development of CAR-Tregs and advanced gene-editing techniques may increase the specificity and safety of therapy. In addition, clinical trials and long-term studies should be conducted to establish the efficacy, safety, and economic feasibility of this innovative approach. This review underscores the transformative potential of CAR-T therapy in the management of rheumatic diseases, particularly in refractory cases. Offering targeted immunomodulation with a minimum of systemic immune suppression, CAR-T therapy could redefine therapeutic paradigms and offer hope for improved outcomes in autoimmune diseases.

The B-cells paradigm in systemic sclerosis: an update on pathophysiology and B-cell-targeted therapies

Systemic sclerosis (SSc) is considered a rare autoimmune disease in which there are alterations of both the innate and adaptive immune response resulting in the production of autoantibodies. Abnormalities of the immune system compromise the normal function of blood vessels leading to a vasculopathy manifested by Raynaud's phenomenon, an early sign of SSc . As a consequence of this reactive picture, the disease can evolve leading to tissue fibrosis. Several SSc-specific autoantibodies are currently known and are associated with specific clinical manifestations and prognosis. Although the pathogenetic role of these autoantibodies is still unclear, their production by B cells and plasma cells suggests the importance of these cells in the development of SSc. This review narratively examines B-cell dysfunctions and their role in the pathogenesis of SSc and discusses B-cell-targeted therapies currently used or potentially useful for the management of end-organ complications.

Effector and regulatory B-cell imbalance in systemic sclerosis: cooperation or competition?

B cells play a central role in the pathogenesis of systemic sclerosis (SSc). Most B-cell studies have focused on their pathological role as antibody producers. However, in addition to immunoglobulin secretion, these cells have a wide range of functions in the immune response, including antigen presentation to T cells and cytokine production. Importantly, not all B-cell subsets promote the immune response. Regulatory B cells (Bregs) attenuate inflammation and contribute to the maintenance of immune tolerance. However, effector B cells (Beffs) positively modulate the immune response through the production of various cytokines. In SSc, Bregs are insufficient and/or dysfunctional. B-cell-targeting biologics have been trialled with promising results in the treatment of SSc. These therapies can affect Bregs or Beffs, which can potentially limit their long-term efficacy. Future strategies might involve the modulation of effector B cells in combination with the stimulation of regulatory subsets. Additionally, the monitoring of individual B-cell subsets in patients may lead to the discovery of novel biomarkers that could help predict disease relapse or progression. The purpose of this review is to summarize the relevant literatures and explain how Bregs and Beffs jointly participate in the pathogenesis of SSc.

Disturbed Complement Receptor Expression Pattern of B Cells Is Enhanced by Toll-like Receptor CD180 Ligation in Diffuse Cutaneous Systemic Sclerosis

Autoantibody production is a hallmark of systemic sclerosis (SSc) and the most extensively studied role of B cells in the pathogenesis of the disease. However, the potential involvement of innate immune molecules in B-cell dysfunction in SSc is less understood. B-cell activation is an early event in the pathogenesis of SSc and is influenced by complement receptors (CRs) and Toll-like receptors (TLRs), shaping antibody responses. CR2 and CR1 modulate B-cell activation, and the roles of CR3 and CR4 are associated with autoimmune conditions. We investigated the expression of CRs in B cells from patients with the more severe form of the disease, diffuse cutaneous SSc (dcSSc), and the effect of TLR CD180 ligation on their expression. We found no significant difference in the basal expression of CD21 and CD11c in B cells between dcSSc and healthy controls (HCs). However, reduced basal CD11b expression in B cells in dcSSc compared to HCs, accompanied by a decrease in CD35 and an increase in CD11c expression following CD180 ligation may promote plasma cell formation and autoantibody production. Additionally, we searched for correlations between dcSSc-associated anti-DNA topoisomerase I (Scl-70) autoantibody, anti-citrate synthase (CS) natural autoantibody and complement component 3 (C3) levels and found a negative correlation between C3 and anti-CS autoantibody in dcSSc but not in HCs, supporting the hypothesis that natural autoantibodies could activate the complement system contributing to tissue injury in SSc.

The Use of "Acellbia"-A Biosimilar of Rituximab in Systemic Sclerosis

The possibilities of modern therapy for systemic sclerosis (SSc) remains limited, since most of the used drugs do not have a disease-modifying effect. This encourages the study of new approaches that potentially affect the fundamental pathological processes underlying the disease. One example is anti-B-cell therapy, in particular rituximab (RTX). Until now RTX does not have a registration for the treatment of SSc, but there is a large positive experience of its use, which is reflected in recent meta-analyses and clinical recommendations. Complicated and expensive methods for obtaining genetically engineered biological drugs (biologics) have contributed to the emergence of more accessible biosimilars, one of which is the RTX biosimilar, Acellbia (Biocad, Russian Federation). The ''biosimilar'' versions of RTX might reduce the cost of therapy and increase patients accessibility to this treatment option. The RTX biosimilar Acellbia (ACB) has received approval in Russian Federation in 2014 for all indications held by reference RTX (including rheumatoid arthritis and ANCA-associated vasculitis).

IBPA a mutual prodrug of ibuprofen and acetaminophen alleviates inflammation, immune dysregulation and fibrosis in preclinical models of systemic sclerosis

Systemic sclerosis (SSc) is a devastating autoimmune illness with a wide range of clinical symptoms, including vascular abnormalities, inflammation, and persistent and progressive fibrosis. The disease's complicated pathophysiology makes it difficult to develop effective therapies, necessitating research into novel therapeutic options. Molecular hybridization is a strategy that can be used to develop new drugs that act on two or multiple targets and represents an interesting option to be explored for the treatment of complex diseases. We aimed to evaluate the effects of a hybrid mutual prodrug of ibuprofen and acetaminophen (IBPA) in peripheral blood mononuclear cells (PBMC) isolated from SSc patients, and in an in vivo model of SSc induced in BALB/c mice by intradermal injections of hypochlorous acid (HOCl) for 6 weeks. The mice were treated at the same time with daily intraperitoneal injections of IBPA (40 mg/kg). Pulmonary and skin fibrosis as well as immune responses were evaluated. IBPA significantly decreased the release of cytokines in PBMC culture supernatants from SSc patients after stimulation with phytohemagglutinin-M (IL-2, IL-4, IL-6, IL-10, IL-13, IL-17A, TNF and IFN-γ).In HOCl-induced SSc, IBPA treatment prevented dermal and pulmonary fibrosis, in addition to reducing CD4 + T and B cells activation and reversing the M2 polarization of macrophages in spleen cells, and inhibiting IFN-γ secretion in splenocyte cultures. These results show the anti-inflammatory and antifibrotic effects of IBPA in SSc and highlight the therapeutic potential of this mutual prodrug, providing support for future studies.

Toll-like Receptor Homologue CD180 Ligation of B Cells Upregulates Type I IFN Signature in Diffuse Cutaneous Systemic Sclerosis

Type I interferon (IFN-I) signaling has been shown to be upregulated in systemic sclerosis (SSc). Dysregulated B-cell functions, including antigen presentation, as well as antibody and cytokine production, all of which may be affected by IFN-I signaling, play an important role in the pathogenesis of the disease. We investigated the IFN-I signature in 71 patients with the more severe form of the disease, diffuse cutaneous SSc (dcSSc), and 33 healthy controls (HCs). Activation via Toll-like receptors (TLRs) can influence the IFN-I signaling cascade; thus, we analyzed the effects of the TLR homologue CD180 ligation on the IFN-I signature in B cells. CD180 stimulation augmented the phosphorylation of signal transducer and activator of transcription 1 (STAT1) in dcSSc B cells (p = 0.0123). The expression of IFN-I receptor (IFNAR1) in non-switched memory B cells producing natural autoantibodies was elevated in dcSSc (p = 0.0109), which was enhanced following anti-CD180 antibody treatment (p = 0.0125). Autoantibodies to IFN-Is (IFN-alpha and omega) correlated (dcSSc p = 0.0003, HC p = 0.0192) and were present at similar levels in B cells from dcSSc and HC, suggesting their regulatory role as natural autoantibodies. It can be concluded that factors other than IFN-alpha may contribute to the elevated IFN-I signature of dcSSc B cells, and one possible candidate is B-cell activation via CD180.

Application of blinatumomab, a bispecific anti-CD3/CD19 T-cell engager, in treating severe systemic sclerosis: A case study

Systemic sclerosis, a severe inflammatory autoimmune disease, shares a common thread with cancer through the underlying mechanism of inflammation. This inflammatory milieu not only drives the immune dysregulation characteristic of autoimmune diseases but also plays a pivotal role in the pathogenesis of cancer. Among the cellular components involved, B cells have emerged as key players in hematologic tumor and autoimmune disease, contributing to immune dysregulation and persistent tissue fibrosis in systemic sclerosis, as well as tumor progression and immune evasion in cancer. Consequently, novel therapeutic strategies targeting B cells hold promise in both conditions. Recent exploration of CD19 CAR T cells in severe systemic sclerosis patients has shown great potential, but also introduced possible risks and drawbacks associated with viral vectors, prolonged CAR T cell persistence, lengthy production timelines, high costs, and the necessity of conditioning patients with organotoxic and fertility-damaging chemotherapy. Given these challenges, alternative CD19-depleting approaches are of high interest for managing severe systemic autoimmune diseases. Here, we present the pioneering use of blinatumomab, a bispecific anti-CD3/anti-CD19 T cell engager in a patient with progressive, severe systemic sclerosis, offering a promising alternative for such challenging cases.

Patients with systemic sclerosis and low CD4 numbers after autologous stem cell transplantation have a favorable outcome

BACKGROUND

Treatment with high-dose chemotherapy followed by autologous hematopoietic stem cell transplantation (aHSCT) is an intensive treatment option for patients with severe forms of systemic sclerosis (SSc). Even though associated with a high treatment related mortality, the results in this high-risk population are generally favourable. The knowledge on the potential mechanism of action of this therapy and how it can improve patients with SSc is crucial to better select the right patients for aHSCT.

METHODS

This is a monocentric retrospective study from Tübingen, Germany, including 32 patients who underwent aHSCT. Peripheral blood samples were analysed for different lymphocyte subsets at various timepoints before and after aHSCT. Patients were divided into responders and non-responders according to the modified Rodnan skin score and lung function test in the three years following aHSCT.

RESULTS

Responders showed significantly lower levels of cluster of differentiation (CD)4 positive T cells in the first months after aHSCT (month 1 and 3), B cells (month 3 and 6 after aHSCT) and natural killer cells (month 1). Mantel-cox test showed a significant deviation of the probability curves, i.e. patients with lower CD4 + T cells and natural killer cells one month and B cells after 3 months after stem cell transplantation had a higher probability to belong to the responder group.

CONCLUSIONS

Taken together, this study supports the theory that a profound CD4 + T cell and B cell lymphopenia is important for patients with SSc to achieve a sustained response after aHSCT.

Anti-topoisomerase 1 Antibody Level Changes after B Cell Depletion Therapy in Systemic Sclerosis

The aim of our study was to assess the relationship between the changes of antinuclear autoantibodies (ANAs) and autoantibodies to topoisomerase 1 (anti-Topo 1) in systemic sclerosis (SSs) patients on rituximab (RTX) therapy. The prospective study included 88 patients (73 women) with a mean age of 47 (17-71) years. The mean disease duration was 5.9 ± 4.8 years. The mean follow-up period was more than 2 years (27 (12-42) months). We documented a statistically significant change in skin score, the disease activity index, improvement of pulmonary function and reduction of mean dose of prednisolone after RTX treatment. There was a significant decrease in the number of patients with high levels of ANA and overall decrease of the ANA and anti-Topo 1 levels. A moderate positive statistically significant correlation was found between ANA and anti-Topo 1 (r = 0.403). In the group of patients positive for anti-Topo 1 there were a more pronounced depletion of B lymphocytes, significantly higher increase in forced vital capacity and diffusion capacity, decrease in the disease activity index, compared with patients negative for anti-Topo 1. We observed the decline in the level of ANA and anti-Topo 1 in SSc patients after RTX therapy, and it was correlated by an improvement of the main outcome parameters of the disease. Therefore, anti-Topo 1 positivity could be considered as a predictor of a better response to RTX treatment, especially in SSc patients with hyperproduction of anti-Topo 1.

The Microbiome in Systemic Sclerosis: Pathophysiology and Therapeutic Potential

Systemic sclerosis (SSc), also known as scleroderma, is an autoimmune disease with unknown etiology characterized by multi-organ fibrosis. Despite substantial investigation on SSc-related cellular and molecular mechanisms, effective therapies are still lacking. The skin, lungs, and gut are the most affected organs in SSc, which act as physical barriers and constantly communicate with colonized microbiota. Recent reports have documented a unique microbiome signature, which may be the pathogenic trigger or driver of SSc. Since gut microbiota influences the efficacy and toxicity of oral drugs, evaluating drug-microbiota interactions has become an area of interest in disease treatment. The existing evidence highlights the potential of the microbial challenge as a novel therapeutic option in SSc. In this review, we have summarized the current knowledge about molecular mechanisms of SSc and highlighted the underlying role of the microbiome in SSc pathogenesis. We have also discussed the latest therapeutic interventions using microbiomes in SSc, including drug-microbiota interactions and animal disease models. This review aims to elucidate the pathophysiological connection and therapeutic potential of the microbiome in SSc. Insights into the microbiome will significantly improve our understanding of etiopathogenesis and developing therapeutics for 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.

Reconstitution of the immune system and clinical correlates after stem cell transplantation for systemic sclerosis

Systemic sclerosis (SSc) is a chronic autoimmune disease that includes fibrosis, diffuse vasculopathy, inflammation, and autoimmunity. Autologous hematopoietic stem cell transplantation (auto-HSCT) is considered for patients with severe and progressive SSc. In recent decades, knowledge about patient management and clinical outcomes after auto-HSCT has significantly improved. Mechanistic studies have contributed to increasing the comprehension of how profound and long-lasting are the modifications to the immune system induced by transplantation. This review revisits the immune monitoring studies after auto-HSCT for SSc patients and how they relate to clinical outcomes. This understanding is essential to further improve clinical applications of auto-HSCT and enhance 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.

Therapeutic Options for Systemic Sclerosis: Current and Future Perspectives in Tackling Immune-Mediated Fibrosis

Systemic sclerosis (SSc) is a severe auto-immune, rheumatic disease, characterized by excessive fibrosis of the skin and visceral organs. SSc is accompanied by high morbidity and mortality rates, and unfortunately, few disease-modifying therapies are currently available. Inflammation, vasculopathy, and fibrosis are the key hallmarks of SSc pathology. In this narrative review, we examine the relationship between inflammation and fibrosis and provide an overview of the efficacy of current and novel treatment options in diminishing SSc-related fibrosis based on selected clinical trials. To do this, we first discuss inflammatory pathways of both the innate and acquired immune systems that are associated with SSc pathophysiology. Secondly, we review evidence supporting the use of first-line therapies in SSc patients. In addition, T cell-, B cell-, and cytokine-specific treatments that have been utilized in SSc are explored. Finally, the potential effectiveness of tyrosine kinase inhibitors and other novel therapeutic approaches in reducing fibrosis is highlighted.