Is there a role for B-cell depletion as therapy for scleroderma A case report and review of the literature. Semin Arthritis Rheum. 2010;40:127-136. [PMID: 20004954 DOI: 10.1016/j.semarthrit.2009.09.003]

Beyond circulating B cells: Characteristics and role of tissue-infiltrating B cells in systemic sclerosis

B cells play a key role in the pathophysiology of systemic sclerosis (SSc). While they are less characterized than their circulating counterparts, tissue-infiltrating B cells may have a more direct pathological role in tissues. In this review, we decipher the multiple evidence of B cells infiltration in the skin and lungs of SSc patients and animal models of SSc but also of other chronic fibrotic diseases with similar pathological mechanisms such as chronic graft versus host disease, idiopathic pulmonary fibrosis or morphea. We also recapitulate the current knowledge about mechanisms of B cells infiltration and their functions in tissues. Finally, we discuss B cell targeted therapies, and their specific impact on infiltrated B cells. Understanding the local consequences of infiltrating B cells is an important step for a better management of patients and the improvement of therapies in SSc.

CD19: a promising target for systemic sclerosis

Systemic sclerosis (SSc) is an autoimmune disease characterized by immune dysregulation, vascular damage, and fibrosis. B cells play a significant role in SSc through autoantibody production, cytokine secretion, and T cell regulation. Autoantibodies like anti-topoisomerase I and anti-RNA polymerase III are specific to SSc and linked to clinical features such as skin and lung involvement. B cell depletion therapies, particularly anti-CD20 antibodies like rituximab, have shown benefits in treating SSc, improving skin and lung disease symptoms. However, CD19, another B cell marker, is more widely expressed and has emerged as a promising target in autoimmune diseases. CD19-targeted therapies, such as CAR T cells and Uplizna® (inebilizumab), have demonstrated potential in treating refractory autoimmune diseases, including SSc. Uplizna® offers advantages over rituximab by targeting a broader range of B cells and showing higher efficacy in specific patient subsets. Clinical trials currently investigate Uplizna®'s effectiveness in SSc, particularly in severe cases. While these therapies offer hope, long-term safety and efficacy remain unknown. SSc is still a complex disease, but advancing B cell-targeted treatments could significantly improve patient outcomes and knowledge about the pathogenesis.

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.

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.

Development of Anti-fibrotic Therapy in Stricturing Crohn's Disease: Lessons from Randomized Trials in Other Fibrotic Diseases

Intestinal fibrosis is considered an inevitable complication of Crohn's disease (CD) that results in symptoms of obstruction and stricture formation. Endoscopic or surgical treatment is required to treat the majority of patients. Progress in the management of stricturing CD is hampered by the lack of effective anti-fibrotic therapy; however, this situation is likely to change because of recent advances in other fibrotic diseases of the lung, liver and skin. In this review, we summarized data from randomized controlled trials (RCT) of anti-fibrotic therapies in these conditions. Multiple compounds have been tested for the anti-fibrotic effects in other organs. According to their mechanisms, they were categorized into growth factor modulators, inflammation modulators, 5-hydroxy-3-methylgultaryl-coenzyme A (HMG-CoA) reductase inhibitors, intracellular enzymes and kinases, renin-angiotensin system (RAS) modulators and others. From our review of the results from the clinical trials and discussion of their implications in the gastrointestinal tract, we have identified several molecular candidates that could serve as potential therapies for intestinal fibrosis in CD.

Safety and efficacy of rituximab in connective tissue disease-associated interstitial lung disease: A systematic review and meta-analysis

OBJECTIVE

Rituximab (RTX) is widely used in the treatment of connective tissue disease (CTD) because it can target and eliminate pathogenic B cells. Interstitial lung disease (ILD) is one of the common complications of CTD; however, the clinical benefits of RTX in connective tissue disease-associated interstitial lung disease (CTD-ILD) are still controversial. This meta-analysis was performed to systematically evaluate the efficacy and safety of RTX in CTD-ILD patients.

METHODS

We performed a systematic online query in PubMed, Cochrane, and Embase up to February 2020. Randomized controlled trials and observational studies on the use of RTX and conventional treatment in CTD-ILD patients were comprehensively reviewed and investigated.

RESULTS

In total, 6 studies, including 242 participants, were analysed. The pooled results showed that RTX is superior to conventional treatment methods in improving forced vital capacity and modified Rodnan skin scores (MRSS) in patients with systemic sclerosis (P＜0. 05), but there was no statistically significant difference between RTX and conventional treatment method in the improvement of lung diffusion function. The risk of adverse effects declined in the RTX therapy groups compared with the conventional therapy groups in terms of infection and the blood system.

CONCLUSION

The pooled results of this meta-analysis indicated that RTX is well tolerated, and RTX is able to improve or stabilize pulmonary function in CTD-ILD patients.

Efficacy of cyclophosphamide in treating connective tissue disease-related interstitial lung diseases

Interstitial lung diseases (ILDs) are some of the first and most serious complications of connective tissue diseases (CTDs). However, the pathogenesis of CTD-related ILDs (CTD-ILDs) is still unclear and their treatment often depends on functional and radiographic disease progression as well as on patient age and comorbidities. It can be difficult to manage CTD-ILDs due to their heterogeneous nature, the lack of robust therapeutic data, and the few well-defined outcome measures. This review focuses on cyclophosphamide due to its crucial role in the treatment of systemic sclerosis-related ILD, particularly in the case of patients with progressive ILD. This narrative review was performed using PubMed, Medline, and Cochrane Library databases to retrieve English language papers published between 2000 and April 2020 concerning the treatment of CTD-ILDs with cyclophosphamide.

A novel bispecific antibody alleviates bleomycin-induced systemic sclerosis injury

Systemic sclerosis (SSc) is induced by variety of factors and eventually causes multiple organ damage. In recent years, biological agents targeting cytokines and cell surface molecules have gradually come to market. Here, the anti-inflammatory and antifibrotic effects of a novel bispecific antibody (FL-BsAb1/17) targeting interleukin-17A (IL-17A) and interleukin-1β (IL-1β) were detected. Bleomycin (BLM) was subcutaneously injected for 21 consecutive days to establish the SSc mouse model, and mice were subsequently treated with etanercept or different doses (1, 5, 10 mg/kg) of FL-BsAb1/17. The results showed that FL-BsAb1/17 treatment (10 mg/kg, 5 mg/kg) significantly attenuated BLM-induced SSc-like inflammation by inhibiting the expression of inflammatory factors (IL-17A, IL-1β, IL-8, IL-22, IL-23, IL-6) and fibrosis, with specific outcomes of dermis thickening and lung fibrosis, by inhibiting the expression of fibrotic factors (TGF-β, α-sma, Col-1, Col-3) in the serum, skin and lungs. In addition, FL-BsAb1/17 (10 mg/kg, 5 mg/kg) downregulated protein levels of TGF-β and phosphorylated Smad2/3 in the skin and lungs and reduced collagen 1 protein levels. This indicated that FL-BsAb1/17 can inhibit the development of fibrosis by inhibiting the TGF-β/Smad2/3 signaling pathway. FL-BsAb1/17 (10 mg/kg, 5 mg/kg) could also effectively reduce the content of MDA, increase the activity of SOD and CAT, and improve the total antioxidant capacity (T-AOC). In conclusion, FL-BsAb1/17 alleviated BLM-induced SSc by downregulating inflammatory cascades, relieving oxidative stress and inhibiting TGF-β/Smad2/3 signaling. These data suggest that FL-BsAb1/17 has potential as a novel therapeutic candidate for SSc.

Is biological therapy in systemic sclerosis the answer?

Systemic sclerosis is a systemic fibrosing disorder associated with significant morbidity and mortality, with no universally accepted disease-modifying therapy. Significant advances in the understanding of systemic sclerosis in recent years have guided the exploration of biological drugs in systemic sclerosis. In this narrative review, we summarize the published literature on biologic therapies in systemic sclerosis. A double-blind randomized trial, and an open label trial of tocilizumab (which antagonizes the interleukin 6 receptor), identified potential benefits in skin and lung fibrosis in systemic sclerosis; however, these differences failed to attain statistical significance. Two open-label trials compared rituximab (which depletes B lymphocytes) to conventional treatment/ cyclophosphamide in systemic sclerosis-associated interstitial lung disease (ILD), and revealed significant improvements in lung functions and skin disease with rituximab. Significant observational data also support the use of rituximab in skin, lung, muscle and joint manifestations of systemic sclerosis. Abatacept (which blocks T lymphocyte activation) has demonstrated utility for skin and joint disease in systemic sclerosis; a recent clinical trial failed to demonstrate benefits in improving skin thickness compared to placebo. Agents targeting type I interferons, interleukin 17 pathway, CD19 and plasma cells hold promise in systemic sclerosis; however, high-quality evidence is lacking. The results of different ongoing clinical trials targeting B lymphocytes, T lymphocytes, various cytokines (interleukins 6, 17, 4, 13, IL-1α), platelet-derived growth factor receptor, proteasome, integrins or oncostatin M may help guide future therapeutic regimens with biological agents in systemic sclerosis.

Targeting very early systemic sclerosis: a case-based review

It is unknown whether treatment in very early/early systemic sclerosis (SSc) can affect long-term outcomes. A case-based review was conducted (i) to assess the effect of rituximab (RTX) in very early SSc and (ii) to explore how many clinical trials in SSc targeted early disease and whether treatment of these patients led to better clinical outcomes. We identified cases of very early SSc from our department and performed a search in MEDLINE and Scopus databases for clinical trials in SSc during 2005-2018. Two cases are reported where RTX was administered within 24 months from the appearance of Raynaud's. In the first case, there was an improvement in interstitial lung disease as indicated by the improvement in pulmonary function tests and the regression of changes in high-resolution chest computed tomography. In the second case, a good clinical response in skin fibrosis was observed. The review revealed the following: (i) only one-third of the studies were specifically designed to target early disease, (ii) there is confusion related to disease duration definition across SSc clinical trials but an obvious trend towards improvement was evident during the past years, (iii) the question of whether early implementation of therapy may lead to better clinical outcomes cannot be definitely answered based on existing data and (iv) there is still a very low level of incorporation of the new classification criteria in SSc trials. This review suggests that there may be a window of opportunity in SSc and highlights the need for clinical trials targeting very early/early disease.

Rituximab in connective tissue disease-associated interstitial lung disease

INTRODUCTION/OBJECTIVES

To evaluate rituximab (RTX) effectiveness and safety in patients with interstitial lung disease (ILD) related to connective tissue diseases (CTD).

METHODS

Retrospective multicenter cohort study, including patients with CTD-ILD, followed in six Portuguese rheumatology departments until November 2018. ILD diagnosis was based on high-resolution CT (HRCT) and/or lung biopsy. Results of HRCT, pulmonary function tests, and 6-min walking test before and after RTX were compared using the Wilcoxon matched pair test. Safety, including adverse events during treatment and reasons for RTX discontinuation, was also analyzed.

RESULTS

A total of 49 patients were included, with rheumatoid arthritis being the commonest CTD (61.2%). The median interval between CTD onset and ILD diagnosis was 4 years (IQR 1-9.5) and median ILD duration at first RTX administration was 1 year (IQR 0-4). The median RTX treatment duration until the last follow-up was 3 years (IQR 1-6). Usual interstitial pneumonia (UIP) and non-specific interstitial pneumonia (NSIP) were the commonest patterns, occurring in 20 and 18 patients, respectively. One year after RTX first administration, there was a stabilization in carbon monoxide diffusing capacity (DLCO; mean + 5.4%, p = 0.12) and improvement in forced vital capacity (FVC; mean + 4.3%, p = 0.03), particularly in patients with NSIP. Patients with UIP had less promising results, but at 1 year, pulmonary function tests remained stable (DLCO + 2.5%, p = 0.77; FVC + 4.2%, p = 0.16). Infection was the main reason for RTX discontinuation and led to two deaths.

CONCLUSIONS

RTX seems to be a promising treatment for CTD-ILD patients, particularly when NSIP pattern is present. Key points • The use of rituximab in patients with interstitial lung disease related to connective tissue disease is associated with long-standing disease stability in a wide range of systemic rheumatic diseases. • Efficacy results were particularly impressive in patients with non-specific interstitial pneumonia pattern, although in a subgroup of patients with usual interstitial pneumonia pattern, disease progression was also hold with this treatment. • In a large number of patients, rituximab was used in monotherapy and as first-line treatment.

Diagnostic criteria, severity classification and guidelines of systemic sclerosis

Several effective drugs have been identified for the treatment of systemic sclerosis (SSc). However, in advanced cases, not only their effectiveness is reduced but they may be also harmful due to their side-effects. Therefore, early diagnosis and early treatment is most important for the treatment of SSc. We established diagnostic criteria for SSc in 2003 and early diagnostic criteria for SSc in 2011, for the purpose of developing evaluation of each organ in SSc. Moreover, in November 2013, the American College of Rheumatology and the European Rheumatology Association jointly developed new diagnostic criteria for increasing their sensitivity and specificity, so we revised our diagnostic criteria and severity classification of SSc. Furthermore, we have revised the clinical guideline based on the newest evidence. In particular, the clinical guideline was established by clinical questions based on evidence-based medicine according to the New Minds Clinical Practice Guideline Creation Manual (version 1.0). We aimed to make the guideline easy to use and reliable based on the newest evidence, and to present guidance as specific as possible for various clinical problems in treatment of SSc.

Rituximab in the Treatment of Interstitial Lung Disease Associated with Antisynthetase Syndrome: A Multicenter Retrospective Case Review

OBJECTIVE

To assess clinical outcomes including imaging findings on computed tomography (CT), pulmonary function testing (PFT), and glucocorticoid (GC) use in patients with the antisynthetase syndrome (AS) and interstitial lung disease (ILD) treated with rituximab (RTX).

METHODS

We retrospectively identified all patients at 2 institutions with AS-ILD who were treated with RTX. Baseline demographics, PFT, and chest CT were assessed before and after RTX. Two radiologists independently evaluated CT using a standardized scoring system.

RESULTS

Twenty-five subjects at the Brigham and Women's Hospital (n = 13) and University of Pittsburgh Medical Center (n = 12) were included. Antisynthetase antibodies were identified in all patients (16 Jo1, 6 PL-12, 3 PL-7). In 21 cases (84%), the principal indication for RTX use was recurrent or progressive ILD, owing to failure of other agents. Comparing pre- and post-RTX pulmonary variables at 12 months, CT score and forced vital capacity were stable or improved in 88% and 79% of subjects, respectively. Total lung capacity (%) increased from 56 ± 13 to 64 ± 13 and GC dose decreased from 18 ± 9 to 12 ± 12 mg/day. Although DLCO (%) declined slightly at 1 year, it increased from 42 ± 17 to 70 ± 20 at 3 years. The most common imaging patterns on CT were nonspecific interstitial pneumonia (NSIP; n = 13) and usual interstitial pneumonia/fibrotic NSIP (n = 5), of which 5 had concurrent elements of cryptogenic organizing pneumonia.

CONCLUSION

Stability or improvement in pulmonary function or severity of ILD on CT was seen in most patients. Use of RTX was well tolerated in the majority of patients. RTX may play a therapeutic role in patients with AS-ILD, and further clinical investigation is warranted.

Dkk1: A key molecule in joint remodelling and fibrosis

Dickkopf-1 (Dkk-1) is a Wnt signaling pathway inhibitor that has been shown to play an important role in joint remodeling, in experimental models of arthritis and in humans. Recent data suggest that this molecule is involved in the fibrotic process as well.

Rituximab in early systemic sclerosis

OBJECTIVES

(1) Hypothesis testing of the potency of rituximab (RTX) in preventing fibrotic complications and (2) assessing acceptability and feasibility of RTX in early systemic sclerosis (SSc).

METHODS

A small, 24-month, randomised, double-blind, placebo-controlled, single-centre trial in patients with SSc diagnosed <2 years was conducted. Patients received RTX or placebo infusions at t=0, t=15 days and t=6 months. Patients were clinically evaluated every 3 months, with lung function tests and high-resolution CT every other visit. Skin biopsies were taken at baseline and month 3. Immunophenotyping of peripheral blood mononuclear cells was performed at every visit, except at months 9 and 18. Adverse events, course of skin and pulmonary involvement and B cell populations in skin and peripheral blood were evaluated.

RESULTS

In total 16, patients (rituximab n=8, placebo n=8) were included. Twelve patients had diffuse cutaneous SSc. Eighty-eight adverse events (RTX n=53, placebo n=35, p=0.22) and 11 serious adverse events (RTX n=7, placebo n=4, p=0.36) occurred. No unexpected RTX-related events were observed. Mean skin score over time did not differ between the groups. Over time, forced vital capacity and extent of lung involvement slightly improved with RTX, but this difference was insignificant. In peripheral blood B cells depletion was demonstrated.

CONCLUSIONS

No unexpected safety issues were observed with RTX in early SSc. Although this small trial could not confirm or reject potential efficacy of RTX in these patients, future placebo-controlled trials are warranted, specifically in the subgroup of patients with pulmonary involvement.

TRIAL REGISTRATION NUMBER

EudraCT 2008-07180-16; Results.

Rituximab versus cyclophosphamide for the treatment of connective tissue disease-associated interstitial lung disease (RECITAL): study protocol for a randomised controlled trial

Background

Interstitial lung disease (ILD) frequently complicates systemic autoimmune disorders resulting in considerable morbidity and mortality. The connective tissue diseases (CTDs) most frequently resulting in ILD include: systemic sclerosis, idiopathic inflammatory myositis (including dermatomyositis, polymyositis and anti-synthetase syndrome) and mixed connective tissue disease. Despite the development, over the last two decades, of a range of biological therapies which have resulted in significant improvements in the treatment of the systemic manifestations of CTD, the management of CTD-associated ILD has changed little. At present there are no approved therapies for CTD-ILD. Following trials in scleroderma-ILD, cyclophosphamide is the accepted standard of care for individuals with severe or progressive CTD-related ILD. Observational studies have suggested that the anti-CD20 monoclonal antibody, rituximab, is an effective rescue therapy in the treatment of refractory CTD-ILD. However, before now, there have been no randomised controlled trials assessing the efficacy of rituximab in this treatment population.

Methods/design

RECITAL is a UK, multicentre, prospective, randomised, double-blind, double-dummy, controlled trial funded by the Efficacy and Mechanism Evaluation Programme of the Medical Research Council and National Institute for Health Research. The trial will compare rituximab 1 g given intravenously, twice at an interval of 2 weeks, with intravenously administered cyclophosphamide given monthly at a dose of 600 mg/m² body surface area in individuals with ILD due to systemic sclerosis, idiopathic inflammatory myositis (including anti-synthetase syndrome) or mixed connective tissue disease. A total of 116 individuals will be randomised 1:1 to each of the two treatment arms, with stratification based on underlying CTD, and will be followed for a total of 48 weeks from first dose. The primary endpoint for the study will be change in forced vital capacity (FVC) at 24 weeks. Key secondary endpoints include: safety, change in FVC at 48 weeks as well as survival, change in oxygen requirements, total 48-week corticosteroid exposure and utilisation of health care resources.

Discussion

This is the first randomised control trial to study the efficacy of rituximab as first-line treatment in CTD-associated ILD. The results generated should provide important information on the treatment of a life-threatening complication affecting a rare group of CTDs.

Trial registration

ClinicalTrials.gov, NCT01862926. Registered on 22 May 2013.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-017-2016-2) contains supplementary material, which is available to authorized users.

Biologics-induced interstitial lung diseases in rheumatic patients: facts and controversies

INTRODUCTION

Interstitial lung disease (ILD) is a common, devastating pulmonary complication. An increased number of reports suggesting that biological disease modifying antirheumatic drugs (DMARDs) induced or exacerbated ILDs in rheumatoid arthritis (RA) patients has garnered increased attention. Areas covered: This article discusses ILDs induced by or exacerbated during biological therapy in RA patients. The article summarizes the efficacy and safety of a variety of licensed and off-label biologics clinically used for rheumatic diseases, focusing on the onset or exacerbation of RA-associated ILDs (RA-ILDs) in RA patients treated with biologics targeting tumor necrosis factor, CD20, interleukin 1 (IL-1) and IL-6 receptors. Additionally, the pathogenesis of RA-ILDs is discussed. Expert opinion: To some extent, the possibility of biologic-induced RA-ILDs increases the difficulty in choosing an optimal regimen for RA treatment with biological agents, as the relationship between biological therapy safety and the induction or exacerbation of RA-ILDs has not been established. A framework to assess baseline disease severity, particularly standardizing the evaluation of the pulmonary condition stage in RA patients and monitoring the outcome during the biological therapy treatment, is highly needed and may substantially help guide treatment decisions and predict the treatment benefits.

Strategy for treatment of fibrosis in systemic sclerosis: Present and future

Systemic sclerosis (SSc) is a generalized connective tissue disorder characterized by microvascular damage, autoimmunity, and excessive fibrosis of the skin and various internal organs. Regardless of the recent progress in medicine, no radical therapy for SSc has been developed, and the risk of mortality remains high. Therefore, diagnosis in the early disease stage, risk stratification for the development of serious organ involvement and therapeutic intervention with disease-modifying drugs can reduce the maximum degree of fibrosis, leading to improved long-term survival. Recently, new criteria for very early diagnosis of SSc have been proposed, which are expected to be useful for regularly following up patients with very early SSc, regardless of the absence of skin sclerosis, and for detecting the development of internal organ involvement as early as possible. At present, several immunosuppressants, including methotrexate, corticosteroids and cyclophosphamide, are being used for the treatment of fibrosis. Furthermore, mycophenolate mofetil, i.v. immunoglobulins, B-cell depletion, anti-interleukin-6 receptor antibody, autologous hematopoietic stem cell transplantation, rapamycin, pirfenidone and imatinib mesylate are potential candidates for the treatment of SSc, although their efficacy has not been validated. Moreover, targeting transforming growth factor-1 and its signaling pathway or modulating the imbalance between T-helper 1 and 2 immune responses are also attractive therapeutic options. This review describes recent advances in the strategy for treatment of fibrosis in SSc and future perspectives.

A multicenter, open-label, comparative study of B-cell depletion therapy with Rituximab for systemic sclerosis-associated interstitial lung disease

OBJECTIVES

Rituximab (RTX) may favorably affect lung function and skin fibrosis in patients with systemic sclerosis (SSc). We aimed to assess long-term efficacy and safety of RTX in SSc compared to standard treatment.

METHODS

A total of 51 patients with SSc-associated interstitial lung disease were recruited and treated with RTX (n = 33) or conventional treatment (n = 18). Median follow-up was 4 years (range: 1-7). Conventional treatment consisted of azathioprine (n = 2), methotrexate (n = 6), and mycophenolate mofetil (n = 10).

RESULTS

Patients in the RTX group showed an increase in FVC at 2 years (mean ± SD of FVC: 80.60 ± 21.21 vs 86.90 ± 20.56 at baseline vs 2 years, respectively, p = 0.041 compared to baseline). In sharp contrast, patients in the control group had no change in FVC during the first 2 years of follow-up. At the 7 year time point the remaining patients in the RTX group (n = 5) had higher FVC compared to baseline (mean ± SD of FVC: 91.60 ± 14.81, p = 0.158 compared to baseline) in contrast to patients in the control group (n = 9) where FVC deteriorated (p < 0.01, compared to baseline). Direct comparison between the 2 groups showed a significant benefit for the RTX group in FVC (p = 0.013). Improvement of skin thickening was found in both the RTX and the standard treatment group; however, direct comparison between groups strongly favored RTX at all-time points. Adverse events were comparable between groups.

CONCLUSIONS

Our data indicate that RTX has a beneficial effect on lung function and skin fibrosis in patients with SSc. Randomized controlled studies are highly needed.

The role of Dickkopf-1 in joint remodeling and fibrosis: A link connecting spondyloarthropathies and scleroderma?

BACKGROUND

Dickkopf-1 (Dkk-1) is a soluble inhibitor of the canonical Wnt pathway, which plays critical roles in embryonic development. Evidence suggests that this molecule regulates several aspects of both bone biology and fibrosis.

OBJECTIVES

To provide an overview of our current knowledge of the role of Dkk-1 in joint remodeling and fibrosis.

METHODS

We performed an electronic search (Medline) using the following key words: Dickkopf-1 (or Dkk-1), new bone formation, joint remodeling, ankylosing spondylitis, systemic sclerosis (or scleroderma), and fibrosis, supplemented by a manual search of references from retrieved articles.

RESULTS

Dkk-1 is a master regulator of joint remodeling in animal models of arthritis shifting the balance toward new bone formation when its expression is decreased and toward erosion/joint destruction when its expression is increased. In humans, evidence suggests that Dkk-1 may be dysfunctional in patients with ankylosing spondylitis, a prototype bone forming disease. Moreover, data from animal models indicate that Dkk-1 has a protective role against fibrosis in several organs. Recent data suggest that inhibiting the canonical Wnt pathway by overexpression of Dkk-1 could be a way to target TGF-β signaling in fibrotic diseases. Finally, B-cell depletion therapy in systemic sclerosis may exert its effects through TGF-β dependent upregulation of Dkk-1.

CONCLUSIONS

Dkk-1 appears to play a crucial role in both joint remodeling/ectopic ossification and fibrosis, and may be a prospective therapeutic modality for fibrotic diseases or diseases characterized by pathologic joint remodeling.

B cell depletion therapy upregulates Dkk-1 skin expression in patients with systemic sclerosis: association with enhanced resolution of skin fibrosis

BACKGROUND

Rituximab (RTX) may favorably affect skin and lung fibrosis in patients with systemic sclerosis (SSc); however, the underlying molecular mechanisms remain unknown. We aimed to explore the hypothesis that RTX may mediate its antifibrotic effects by regulating the expression of Dickkopf-1 (Dkk-1), an inhibitor of the Wnt pathway.

METHODS

Fourteen patients with SSc and five healthy subjects were recruited. Dkk-1 expression was immunohistochemically assessed in skin biopsies obtained from 11 patients with SSc (8 treated with RTX and 3 with standard treatment), whereas DKK1 gene expression was assessed in 3 patients prior to and following RTX administration.

RESULTS

In baseline biopsies obtained from all patients with SSc but not in healthy subjects, Dkk-1 was undetectable in skin fibroblasts. Following RTX treatment, four out of eight patients had obvious upregulation of Dkk-1 skin expression. Similarly, RTX treatment correlated with a significant 4.8-fold upregulation of DKK1 gene expression (p = 0.030). In contrast, TGFβ expression in the upper dermis was significantly attenuated following treatment. Moreover, this decreased expression of TGFβ in the skin was significantly more pronounced in the subgroup of patients with Dkk-1 upregulation. In this subgroup TGFβ was downregulated by 50.88 % in contrast to only 15.98 % in patients who did not have Dkk-1 upregulation (p = 0.022).

CONCLUSIONS

This is the first study demonstrating a link between B cell depletion and skin Dkk-1 upregulation in patients with SSc. RTX-mediated B cell depletion may mechanistically function via the recently established TGFβ-Dkk-1 axis in improving skin fibrosis.

Clopidogrel treatment may associate with worsening of endothelial function and development of new digital ulcers in patients with systemic sclerosis: results from an open label, proof of concept study

Background

Activated platelets release serotonin that binds 5-HT_2B receptor on fibroblasts leading to fibroblast activation. Clopidogrel, an inhibitor of ADP-dependent platelet activation prevents fibrosis in animal models of systemic sclerosis (SSc). We aimed at assessing whether i) ADP-dependent platelet activation is increased in patients with SSc compared to healthy subjects and patients with rheumatoid arthritis (RA) and ii) whether clopidogrel can effectively suppress ADP-dependent activation, reduce circulating serotonin levels and hence, favorably affect fibrosis or vasculopathy in patients with systemic sclerosis.

Methods

Thirteen patients with SSc were recruited. Platelet activation was assessed by aggregometry prior to and following 14 days of clopidogrel treatment. At the same time points serotonin and soluble vascular cell adhesion molecule 1 (s-VCAM1), a marker of endothelial dysfunction, were measured.

Results

ADP-dependent platelet activation was similar between patients with SSc (n = 13), patients with RA (n = 28) and healthy subjects (n = 22) (mean ± SEM AU*min: 392.1 ± 58.4, 535.5 ± 61.33 and 570.9 ± 42.9 in patients with SSc, patients with RA and healthy subjects respectively, p = 0.14). Clopidogrel treatment significantly reduced platelet activation in patients with SSc (mean ± SEM AU*min: 392.1 ± 58.4 vs 163.8 ± 51.7, p = 0.014). Clopidogrel treatment did not affect serotonin levels but led to a significant increase in s-VCAM1 (p = 0.03). Three patients developed new digital ulcers during the study. The potential association of the study drug with the development of new digital ulcers led to early termination of the study.

Conclusion

Clopidogrel may worsen markers of endothelial function and associate with development of new digital ulcers in patients with SSc.

Clinical trial registration

ISRCTN63206606. Registered 02/Dec/2014.

Recent Treatments of Interstitial Lung Disease with Systemic Sclerosis

Systemic sclerosis (SSc) is a disorder characterized by immune dysfunction, microvascular injury, and fibrosis. Organ involvement in patients with SSc is variable; however, pulmonary involvement occurs in up to 90% of patients with SSc. Interstitial lung disease (ILD) is a major cause of mortality and, thus, a major determinant in the prognosis of patients with SSc. This review summarizes current findings about the characteristics of ILD in patients with SSc, selection of patients with SSc-ILD who are candidates for the treatment, and current treatment options.

Collagen vascular disease-associated interstitial lung disease

Interstitial lung disease (ILD) is an important manifestation of collagen vascular diseases. It is a common feature of scleroderma, and also occurs in dermatomyositis and polymyositis, mixed connective tissue disease, Sjogren’s syndrome, rheumatoid arthritis, systemic lupus erythematosus, and Antineutrophil cytoplasmic antibody-associated vasculitis. When present, it is associated with increased morbidity and mortality, thus making early diagnosis important. In fact, in many patients, ILD may be the first manifestation of a collagen vascular disease. The most common symptoms are cough and dyspnea. The diagnosis is made based on pulmonary function tests showing restrictive lung disease and impaired oxygen diffusion and chest imaging showing ground glass infiltrates, interstitial thickening, and/or fibrosis. The most common histologic finding on lung biopsy is non-specific interstitial pneumonia, though organizing pneumonia and usual interstitial pneumonia may also be seen. Treatment is focused on addressing the underlying collagen vascular disease with immunosuppression, either with corticosteroids or a steroid-sparing agent such as cyclophosphamide, azathioprine, or mycophenolate, although the optimal agent and duration of therapy is not known. There are few clinical trials to guide therapy that focus specifically on the progression of ILD. The exception is in the case of scleroderma-associated ILD, where cyclophosphamide has been shown to be effective.

Effects and safety of rituximab in systemic sclerosis: an analysis from the European Scleroderma Trial and Research (EUSTAR) group

OBJECTIVES

To assess the effects of Rituximab (RTX) on skin and lung fibrosis in patients with systemic sclerosis (SSc) belonging to the European Scleroderma Trial and Research (EUSTAR) cohort and using a nested case-control design.

METHODS

Inclusion criteria were fulfilment of American College of Rheumatology classification criteria for SSc, treatment with RTX and availability of follow-up data. RTX-treated patients were matched with control patients from the EUSTAR database not treated with RTX. Matching parameters for skin/lung fibrosis were the modified Rodnan Skin Score (mRSS), forced vital capacity (FVC), follow-up duration, scleroderma subtype, disease duration and immunosuppressive co-treatment. The primary analysis was mRSS change from baseline to follow-up in the RTX group compared with the control group. Secondary analyses included change of FVC and safety measures.

RESULTS

63 patients treated with RTX were included in the analysis. The case-control analysis in patients with severe diffuse SSc showed that mRSS changes were larger in the RTX group versus matched controls (N=25; -24.0±5.2% vs -7.7±4.3%; p=0.03). Moreover, in RTX-treated patients, the mean mRSS was significantly reduced at follow-up compared with baseline (26.6±1.4 vs 20.3±1.8; p=0.0001). In addition, in patients with interstitial lung disease, RTX prevented significantly the further decline of FVC compared with matched controls (N=9; 0.4±4.4% vs -7.7±3.6%; p=0.02). Safety measures showed a good profile consistent with previous studies in autoimmune rheumatic diseases.

CONCLUSIONS

The comparison of RTX treated versus untreated matched-control SSc patients from the EUSTAR cohort demonstrated improvement of skin fibrosis and prevention of worsening lung fibrosis, supporting the therapeutic concept of B cell inhibition in SSc.

B cells tell scleroderma fibroblasts to produce collagen

In fibrosis fibroblasts are activated and overproduce collagen in a process with unknown drivers and equally unknown brakes that recently implicated a novel and surprising player, the B cell. B cells may be crucially involved in fibrosis in several ways: B cells may produce autoantibodies that can directly stimulate fibroblasts; B cells can produce profibrotic cytokines such as IL-6 or transforming growth factor beta; and, finally, B cells could directly stimulate fibroblasts by a contact-dependent mechanism. Recent experimental evidence suggests that B cells can enhance collagen production by fibroblasts, by a contact-dependent mechanism, and therefore are profibrotic ex vivo. These data strengthen the rationale of pursuing B-cell targeting therapies in systemic sclerosis.

Long-term efficacy of B cell depletion therapy on lung and skin involvement in diffuse systemic sclerosis

OBJECTIVES

To assess the long-term efficacy and safety of single and multiple courses of rituximab therapy in systemic sclerosis (SSc) patients with and without lung disease.

METHODS

A total of 20 SSc patients with a diffuse disease were treated with rituximab. At baseline and during follow-up the lung involvement was evaluated with pulmonary function tests (FVC and DLCO) and with lung high-resolution computed tomography (HRCT).

RESULTS

The skin score, activity, and severity indices improved significantly after 12 months and at final follow-up compared to baseline. After 12 months, there was a significant increase of FVC and TLC compared to baseline (p = 0.024 and p = 0.005, respectively), while the mean DLCO value remained stable. Considering the last available follow-up in six patients with restrictive lung disease at baseline, two patients (33.3%) experienced an increase of more than 10% of FVC, one patient had a decrease of FVC >10%, while in three patients FVC remained stable (50%). After the mean follow-up of 48.5 ± 20.4 months, among the patients with normal lung parameters at baseline, FVC remained stable in 12 (85.7%) and in one patient (14.3%) it increased by more than 10%. At the final follow-up, the alveolar and interstitial HRCT scores remained stable in more than 80% of patients, both in patients with and without restrictive lung disease at baseline.

CONCLUSIONS

Anti-CD20 B cell depletion therapy is effective on skin involvement but seems also to preserve the pulmonary function, as supported by a stable or improved FVC and stable interstitial score, suggesting a possible role of rituximab as a modifying therapy overall in early diffuse SSc.

B lymphocytes and B-cell activating factor promote collagen and profibrotic markers expression by dermal fibroblasts in systemic sclerosis

Introduction

B lymphocytes might play a pathogenic role in dermal fibrosis in systemic sclerosis (SSc). B-cell activating factor (BAFF), a key cytokine for B-cell activation, is increased in the serum and the skin of patients with SSc. However, the ability of B cells directly to stimulate dermal fibroblasts and the role of BAFF are not fully understood. We therefore investigated the involvement of B cells and BAFF in the expression of collagen and profibrotic markers by dermal fibroblasts.

Methods

Cocultures of blood B cells from healthy blood donors and normal or SSc dermal fibroblasts stimulated with anti-IgM and BAFF were performed. Alpha-SMA, TIMP1, MMP9, COL1A1, COL1A2, and COL3A1 mRNA expression were determined by quantitative RT-PCR. Soluble collagen, BAFF, IL-6, IL-1β, TGF-β1, and CCL2 protein secretion were assessed.

Results

Coculture of blood B cells and dermal fibroblasts isolated from SSc patients induced IL-6, TGF-β1, CCL2, and collagen secretion, as well as Alpha-SMA, TIMP1, and MMP9 expression in dermal fibroblasts. Transwell assays demonstrated that this induction was dependent on cell-cell contact. Addition of anti-IgM and BAFF to the coculture increased IL-6, CCL2, TGF-β1, and collagen secretion. B cell- and BAFF-induced collagen secretion was highly reduced by anti-TGF-β1 antibodies.

Conclusions

Our results showed for the first time a direct role of B cells on the production of collagen by dermal fibroblasts, which is further enhanced by BAFF. Thus, these results demonstrate a new pathogenic role of B cells and BAFF in fibrosis and systemic sclerosis.

B cell depletion in scleroderma lung disease: A promising new treatment?

Evidence suggests that B cells may participate in the fibrotic process Based on this experimental evidence, treatment with rituximab (RTX) has been tried in systemic sclerosis (SSc) with promising results. In a randomized controlled study from our research group it was shown that treatment with 2 courses of RTX leads to a significant improvement of lung function at 1 year compared to baseline. All relevant studies have so far reported clinical and/or histologic improvement of skin fibrosis something that adds further evidence in favor of a disease modifying role of RTX in SSc. It is more than obvious that novel therapies for SSc-associated lung disease are needed. A large scale, randomized, controlled study assessing the efficacy of RTX in SSc associated interstitial lung disease is warranted. If RTX turns out to be effective it would be a major therapeutic advance in SSc since it can be administered on a long term basis due to its acceptable safety profile.

Treatment of interstitial lung diseases associated with connective tissue diseases

A variety of interstitial lung diseases (ILDs) have been reported in association with connective tissue diseases (CTDs). ILD is commonly associated with multiple CTDs and accounts for significant morbidity and mortality in these conditions. In rheumatoid arthritis and systemic sclerosis, ILD commonly occurs in the course of these disorders (incidence: 20-44%). The pathological findings of ILDs are similar to those of idiopathic interstitial pneumonia. A wide variety of histopathologic features, such as various types of interstitial pneumonia and airway involvement, have been observed that are specific for ILDs in rheumatoid arthritis, and this high variety makes its pathology complicated. The diagnosis of ILD is generally based on clinical presentation, bronchioalveolar lavage fluid and high-resolution computed tomography, among others. The most important differential diagnosis is infection, especially pneumocystis pneumonia, and treatment-related toxic damage. The immunosuppressive agents most widely used for the treatment of ILDs are cyclophosphamide, azathioprine, mycophenolate mofetil and calcineurin inhibitors. Other therapeutic strategies are currently being extensively studied, such as antifibrotic agents, endothelin-1 receptor antagonists, tyrosine kinase inhibitors and newer biological agents. In this article, we describe novel therapies for ILDs associated with CTDs.

Potential immunologic targets for treating fibrosis in systemic sclerosis: a review focused on leukocytes and cytokines

OBJECTIVES

Systemic sclerosis (SSc) is a connective tissue disease characterized by tissue fibrosis. Although the pathogenesis remains unclear, a variety of cells contribute to the fibrotic process via interactions with each other and production of various cytokines. Recent literature related to the immunologic pathogenesis and future strategies for treating the fibrosis of SSc are discussed and, especially, this literature-based review that includes the authors' perspective, focused on leukocytes and cytokines.

METHODS

A PubMed search for articles published between January 2005 and January 2012 was conducted using the following keywords: systemic sclerosis, leukocyte, cytokine, growth factor, and chemokine. The reference lists of identified articles were searched for further articles.

RESULTS

Targeting profibrogenic cytokines, including transforming growth factor-β, is still a very active area of research in SSc and most cellular studies have focused on the roles of fibroblasts in SSc. However, a growing number of recent studies indicate a role for B cells in the development of SSc and other autoimmune diseases such as systemic lupus erythematosus. Therefore, B-cell-targeted therapies, including currently available monoclonal antibodies against CD19, CD20, CD22, and B-cell-activating factor, belonging to the tumor necrosis factor family represent possible treatment options. Furthermore, the modulation of T-cell costimulatory molecules such as a recombinant fusion protein of cytotoxic T-lymphocyte antigen-4 may be as effective in SSc as it is in treating other autoimmune diseases. Approaches to antagonize interleukin (IL)-1, IL-6, or IL-17A signaling may also be attractive.

CONCLUSIONS

This review describes recent advances in the treatment of fibrosis in SSc patients focused on immunologic strategies, such as leukocyte- or cytokine-targeted therapies.

Treatment of systemic sclerosis-associated calcinosis: a case report of rituximab-induced regression of CREST-related calcinosis and review of the literature

OBJECTIVES

Calcinosis is frequently encountered in patients with systemic sclerosis (SSc) and may be associated with significant morbidity. No treatment has shown so far an unequivocal beneficial effect.

METHODS

We performed an extensive internet search (MEDLINE) using the keywords calcinosis, calcification, scleroderma, systemic sclerosis, and treatment.

RESULTS

Our patient had extensive Calcinosis, Raynaud, Esophagitis, Sclerodactyly, telangiectasia (CREST)-related calcinosis, frequently ulcerating and painful. Following 2 rituximab courses (consisting of 4 weekly infusions, 375 mg/m(2) each), calcinosis significantly improved and pain disappeared. Pharmacologic agents used in the treatment of SSc-associated calcinosis include diltiazem, minocycline, warfarin, biphosphonates, and intravenous immunoglobulin. Other therapeutic approaches include surgical excision, laser vaporization, and extracorporeal shock wave lithotripsy.

CONCLUSIONS

Evidence for all existing therapies is weak and therefore larger scale controlled studies are needed. Rituximab appears as a promising treatment especially in view of recent evidence that this therapy may be also effective in the underlying disease.

Biological treatments and connective tissue disease associated interstitial lung disease

PURPOSE OF REVIEW

There is no specific therapy for interstitial lung disease associated with connective tissue diseases (CTDs-ILD), a potentially fatal condition for some of these patients. This article reviews currently available information on the effects on CTDs-ILD of biological treatments that are increasingly used with considerable success in various systemic diseases.

RECENT FINDINGS

A beneficial effect of antitumor necrosis factor (TNF) agents on CTDs-ILD has been described in sporadic patients with rheumatoid arthritis (RA), systemic sclerosis (SSc) and systemic lupus erythematosus (SLE). However, and despite the fact that there was no clear evidence of pulmonary toxicity of these agents in randomized-controlled trials comprising thousands of patients with RA and spondylarthropathies, new onset or exacerbation of preexisting ILD with high mortality rates has so far been observed in 144 RA patients following anti-TNF treatment in clinical practice. Likewise, administration of the B-cell depleting anti-CD20 antibody rituximab was beneficial for ILD in SSc patients but associated with new-onset ILD in isolated patients with RA and SLE. Pertinent information on other biological treatments is currently lacking.

SUMMARY

Data on the therapeutic role of biological agents in CTDs-ILD is preliminary and controversial. Although preexisting ILD is not a contraindication for these agents, until more information is available their administration should be stopped when new pulmonary symptoms occur.

B-cell depletion therapy in systemic sclerosis: experimental rationale and update on clinical evidence

Systemic sclerosis (SSc) is a systemic rheumatic disease with poor prognosis since therapeutic options are limited. Recent evidence from animal models suggests that B-cells may be actively involved in the fibrotic process. B-cells from tight skin mice, an animal model of scleroderma, display a “hyperresponsive” phenotype; treatment with rituximab (RTX) significantly attenuates skin fibrosis in this animal model. In humans, B-cell infiltration is a prominent finding in most lung biopsies obtained from patients with SSc-associated interstitial lung disease. Several open label studies have assessed the clinical efficacy of RTX in SSc. In most patients skin fibrosis improved; lung function either improved or remained stable. Definite conclusions regarding the clinical efficacy of RTX in SSc cannot be drawn but further exploration with a multicenter, randomized study is warranted.

Cyclophosphamide-refractory scleroderma-associated interstitial lung disease: remarkable clinical and radiological response to a single course of rituximab combined with high-dose corticosteroids

We would like to report our experience of using rituximab in cyclophosphamide refractory, rapidly progressive interstitial lung disease (ILD) in a patient with limited scleroderma. A 40-year-old man presented with 10-week history of inflammatory polyarthritis, which responded to a short course of oral corticosteroids. However, 3 weeks later, he developed new onset of exertional dyspnoea. High-resolution CT of the thorax was suggestive of early ILD. Surgical lung biopsy showed features of fibrotic non-specific interstitial pneumonia. He was diagnosed with scleroderma on the basis of: presence of anticentromere antibodies, Raynaud's phenomenon, pulmonary fibrosis, digital oedema and hypomotility along with a dilated oesophagus. He was treated aggressively with pulse doses of corticosteroids and cyclophosphamide; however, his ILD continued to deteriorate. At this stage, he received rituximab (two pulses of 1 g each), which led to a gradual clinical improvement. Now, 12 months since his rituximab infusion, he walks 2 miles daily without any exertional dyspnoea.

B cells in systemic sclerosis: a possible target for therapy

Systemic sclerosis (SSc) is an autoimmune disease characterized by excessive extracellular matrix (ECM) deposition in the skin and other visceral organs and it is associated with immune activation characterized by autoantibody production, release of various cytokines and T-lymphocyte activation. Several recent lines of evidence in animal models and in SSc patients indicate a potential role for B cells in the SSc. B cells have arisen as a possible player in tissue fibrosis in some experimental models and, since IL-6 produced by B cells, along with TGF-β, may induce matrix synthesis and less collagen degradation, targeting B cells could be one way to reduce ECM deposition and reduce the inflammatory background. Both SSc patients and tight-skin mice, a genetic model of SSc, have intrinsic B-cell abnormalities characterized by chronic B-cell activation. SSc patients present an increased number of naïve B cells and an activation of memory B cells, despite a reduction in their number. B cells from SSc patients exhibit increased expression of CD19. Remarkably, CD19 loss or B-cell depletion using antimouse CD20 antibody suppresses the development of skin hyperplasia and autoimmunity in tight-skin mice. Additionally, recent studies revealed a possible beneficial effect of anti-human CD20 antibody (Rituximab) therapy on skin fibrosis and lung involvement in SSc patients. These studies reported also the safety of Rituximab in SSc patients. All these findings suggest a possible role of antiCD20 treatment in SSc patients.

Rituximab in severe skin diseases: target, disease, and dose

New clinical indications for rituximab seem to appear every day. This review will trace the use of this monoclonal antibody from lymphoid malignancy, to classic autoimmune disease, and specifically severe autoimmune skin diseases. The history leading to different dosing schema with associated pharmacokinetic data will be discussed. A case of livedoid vasculopathy (atrophie blanche) responding to rituximab will illustrate how the response to therapy can help to elucidate previously obscure pathophysiology.

B-cell depletion with rituximab: a promising treatment for diffuse cutaneous systemic sclerosis

Recent preclinical and clinical studies lend support to the notion that B-cell depletion is a promising therapeutic target in patients with diffuse cutaneous systemic sclerosis. A recent open-label trial provides further evidence showing marked effects of rituximab treatment on skin thickening, functional ability, and disease activity in conjunction with effects on lesional and circulating B cells and on interleukin-6 and BAFF (B-cell activating factor of tumor necrosis factor family). The excellent safety profile of rituximab in this and other trials warrants further well-designed clinical trials in larger patient groups combined with comprehensive biomarker studies.

Rituximab in the treatment of systemic sclerosis-associated interstitial lung disease: comment on the article by Yoo

Several lines of evidence from basic research indicate that B cells may contribute to the pathogenesis of systemic sclerosis. Clinical studies as well have provided preliminary data pointing to the direction that B-cell depletion with rituximab might be a therapeutic option for patients with this debilitating disease.