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

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1 doi: / Journal of Dermatology 2016; 43: REVIEW ARTICLE Strategy for treatment of fibrosis in systemic sclerosis: Present and future Koichi YANABA Department of Dermatology, The Jikei University School of Medicine, Tokyo, Japan ABSTRACT 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. Key words: autoimmunity, fibrosis, systemic sclerosis, treatment, vasculopathy. INTRODUCTION Systemic sclerosis (SSc) is a generalized connective tissue disorder characterized by microvascular damage and excessive fibrosis of the skin and various internal organs. Although the pathogenesis of SSc remains obscure, it is regarded as an autoimmune disorder because of the presence of SScassociated autoantibodies and various immunological abnormalities. Recent progress in medicine has dramatically improved the treatment of rheumatic diseases; however, the treatment of SSc remains disappointing. The risk of mortality in patients with SSc is three- to five-times greater than that of an age- and sex-matched population. 1 4 The presence of major organ involvement, including interstitial lung disease (ILD), cardiac involvement, pulmonary arterial hypertension and scleroderma renal crisis, affects the mortality and morbidity in SSc. 2,5,6 Therefore, diagnosis in the early disease stage, risk stratification for the development of serious organ involvement and positive therapeutic intervention with diseasemodifying drugs will reduce disease severity and improve long-term survival. CLASSIFICATION AND CLINICAL COURSE OF SSC It is important to understand the natural history of SSc from the therapeutic viewpoint. SSc is classified into two clinical subsets, limited cutaneous SSc (lcssc) and diffuse cutaneous SSc (dcssc), based on the extent of skin involvement. 7 In lcssc, skin sclerosis is restricted to the hands and feet distal to the elbows and knees, respectively, as well as the face, whereas dcssc causes more extensive skin sclerosis involving the proximal portion of the limbs and trunk. The presence of anticentromere antibody and anti-th/to antibody is associated with lcssc, while that of anti-topoisomerase I antibody and anti-rna polymerases III antibody is linked to dcssc. 8 The onset of lcssc is sometimes unclear because patients with early lcssc generally only present with Raynaud s phenomenon and swollen fingers (Fig. 1a). After several years, skin sclerosis of the fingers, and occasionally the hands and forearms, slowly progresses. Patients with lcssc have a low frequency of internal organ involvement, including ILD and scleroderma renal crisis, although the risk of pulmonary arterial hypertension is relatively high, particularly after more than 10 years following Correspondence: Koichi Yanaba, M.D., Ph.D., Department of Dermatology, The Jikei University School of Medicine, Nishishimbashi, Minato-ku, Tokyo , Japan. yanaba@jikei.ac.jp Received 4 June 2015; accepted 6 June Japanese Dermatological Association

2 Treatment of fibrosis in systemic sclerosis (a) (b) and abnormal nail fold capillary changes the representative vascular manifestations of SSc often appear before the onset of SSc. Ischemia reperfusion injury following Raynaud s phenomenon generates reactive oxygen species, resulting in vascular endothelial cell damage and platelet activation. 14,15 Vascular damage occurs in almost all organs, even without any clinical vascular involvement. 16 Endothelial cell damage and platelet activation are accompanied by perivascular cell infiltration. In the early skin lesions of SSc, mononuclear cell infiltration, consisting mostly of CD4 + T cells and a few B cells and macrophages, is observed around small blood vessels in the dermis. 17,18 The degree of cell infiltration correlates with both the degree and progression of skin thickening. 18 These cells are potential candidates for producing various cytokines, chemokines, growth factors and autoantibodies. Fibrosis gradually appears after the development of vascular damage and inflammatory response. Inflammation and vascular damage appear to induce the activation of fibroblasts. SSc fibroblasts show increased production of extracellular matrix (ECM) proteins, including type 1 collagen, leading to excessive deposition and accumulation of ECM proteins in the skin and internal organs; this process is responsible for the clinical features of SSc. 19 Among various cytokines, transforming growth factor (TGF)-b has been considered to play a pivotal role in the fibrosis of SSc. TGF-b induces the production of ECM proteins in mesenchymal cells. 20 Furthermore, SSc fibroblasts show overexpression of TGF-b receptors, which correlates positively with the augmented expression of type 1 collagen gene expression, 21 suggesting that enhanced TGF-b released from various types of cells, including inflammatory infiltrates, fibroblasts, endothelial cells and mesenchymal cells, activates fibroblasts in SSc. Figure 1. Natural course of systemic sclerosis (SSc). (a) The clinical course of limited cutaneous SSc (lcssc) is very slow. After several years following Raynaud s phenomenon, gradual progression of skin sclerosis is observed. Pulmonary arterial hypertension may appear after more than 10 years following the onset. (b) The clinical course of diffuse cutaneous SSc (dcssc) is rapid. The extent and severity of skin sclerosis reach a peak within 2 3 years after its onset and shows gradual improvement. dcssc often leads to organ involvement, including interstitial lung disease, kidney involvement and heart involvement. the onset of lcssc. 9 In contrast, dcssc is a rapidly progressing disease with significant internal organ involvement, which affects the prognosis (Fig. 1b). The extent and severity of skin sclerosis in dcssc generally peak within 2 3 years after its onset, followed by a period of plateauing, and then show gradual improvement, although the degree of improvement is variable. 7,10 13 Therefore, the management of fibrosis in SSc is the general aim for patients with dcssc. MECHANISMS OF DEVELOPMENT OF SSC Although the precise mechanisms of SSc remain unclear, vasculopathy and autoimmunity are supposed to precede the development of fibrosis in SSc (Fig. 2). Raynaud s phenomenon 2016 Japanese Dermatological Association VERY EARLY DIAGNOSIS OF SSC The American College of Rheumatology (ACR) preliminary classification criteria for definite SSc, published in 1980, 22 have been actually used as diagnostic criteria in clinical practice for a long time, although the criteria were not designed for diagnostic purposes but rather to establish a standard for definite disease in order to compare groups of patients from different clinics. The criteria adopted scleroderma proximal to the metacarpophalangeal or metatarsophalangeal joints as the major criterion, and sclerodactyly, digital pitting scars, loss of substance of the distal finger pad or bibasilar pulmonary fibrosis as the minor criteria; the presence of one major or two more minor criteria were required to identify SSc. These criteria have been externally validated to classify established SSc, whereas they mainly focus on fibrotic manifestations and do not include the presence of SSc-associated autoantibodies, Raynaud s phenomenon or abnormal nail fold capillary changes, which are the main clinical features of early SSc and lcssc. It has been reported that only 34% of patients with lcssc fulfill these criteria. 23 Therefore, new classification criteria for SSc were published by the ACR and the European League against Rheumatism (EULAR) in 2013 (Table 1). 24,25 These criteria include the presence of puffy fingers, abnormal nail fold capillaries, Raynaud s phenomenon and SSc-associated autoantibodies, suggesting that they would 47

3 K. Yanaba Figure 2. Possible mechanism of fibrosis in systemic sclerosis (SSc). Vasculopathy and autoimmunity precede the development of fibrosis. Ischemia perfusion injury following Raynaud s phenomenon causes endothelial cell damage and platelet activation, resulting in leukocyte infiltration and subsequent secretion of various cytokines, chemokines, growth factors and autoantibodies. Inflammation and vascular damage induce fibroblast activation, leading to augmented synthesis of extracellular matrix (ECM) proteins. IL, interleukin; TGF, transforming growth factor. be more sensitive for the classification of lcssc and early SSc. However, it has been reported that 23% of patients with Raynaud s phenomenon plus abnormal nail fold capillaries, 22% of patients with Raynaud s phenomenon plus SSc-associated autoantibodies and 66% of patients with Raynaud s phenomenon plus abnormal nail fold capillaries plus SSc-associated autoantibodies develop SSc during the 5-year follow-up period, 26 although none of these patients satisfy the ACR/EULAR criteria at initial presentation. In order to identify patients with early SSc, new criteria for very early diagnosis of SSc (VEDOSS) have proposed by the EULAR Scleroderma Trial and Research Group (EUSTAR) (Fig. 3). 27 According to VEDOSS, very early SSc is suspected when three red flags are present: Raynaud s phenomenon, puffy fingers and antinuclear antibody positivity. The suspicion is then confirmed by the presence of abnormal nail fold capillaries and SSc-associated autoantibodies (anticentromere or anti-topoisomerase I antibody). Importantly, skin sclerosis is not included in the VEDOSS criteria. According to the VEDOSS criteria, 89% of patients with three red flags are classified as very early SSc. 28 Moreover, 56% of patients fulfilling the VEDOSS criteria do not meet the new ACR/EULAR criteria, 28 while nearly 80% of patients with VEDOSS already have ILD and/or gastrointestinal involvement. 29 Thus, it would be important to follow up patients with very early SSc regularly, regardless of the absence of skin sclerosis, to detect the development of internal organ involvement as early as possible. SIGNIFICANCE OF EVALUATING THE SEVERITY OF SKIN SCLEROSIS Skin sclerosis is the hallmark of SSc, but it is not a life-threatening symptom. Therefore, many physicians tend to disregard its evaluation. However, it has been shown that the extent of skin sclerosis reflects the severity of organ involvement and affects long-term survival. At 5 and 10 years, survival is 86 95% and 77 92%, respectively, in patients with lcssc and 67 86% and 49 72%, respectively, in patients with dcssc. 2,30 32 Severe skin sclerosis, defined as modified Rodnan skin thickness score (MRSS) of 20 or more, is a risk factor for scleroderma renal crisis and heart involvement, leading to early mortality, 33 whereas the development of ILD is not associated with the extent of skin sclerosis in patients with dcssc. 33,34 Therefore, the extent of Japanese Dermatological Association

4 Treatment of fibrosis in systemic sclerosis Table 1. ACR/EULAR classification criteria for systemic sclerosis 24,25 Criterion Score 1. Skin thickening of the fingers of both hands 9 extending proximally to the metacarpophalangeal joints 2. Skin thickening of the fingers only Puffy fingers 2 Sclerodactyly of the fingers 4 3. Fingertip lesions Digital tip ulcers 2 Fingertip pitting scars 3 4. Telangiectasia 2 5. Abnormal nail fold capillaries 2 6. Pulmonary arterial hypertension and/or 2 interstitial lung disease 7. Raynaud s phenomenon 3 8. SSc-associated autoantibodies 3 (maximum score, 3) Anticentromere Anti-topoisomerase Anti-RNA polymerase III Patients with a total score 9 are classified as having definite SSc. ACR, American College of Rheumatology; EULAR, European League against Rheumatism; SSc, systemic sclerosis. skin sclerosis reflects the severity of visceral organ involvement in dcssc and, in particular, of heart and renal involvement. Furthermore, changes in the severity of skin sclerosis are also considered to be meaningful. Patients with dcssc who experience rapid progression of skin sclerosis are at increased risk of mortality, scleroderma renal crisis and heart involvement A high skin thickness score and persistent skin sclerosis are associated with poor survival, while improvements in skin sclerosis contribute to not only better survival but also improved functional ability and quality of life. 12,13,33 Moreover, patients with serious complications of one organ tend to have another serious organ complication. 6 Thus, assessing longitudinal changes in skin sclerosis may be an important clinical tool for patient risk stratification and encourage further therapeutic intervention. Reducing the MRSS score is not an appropriate goal of therapy for SSc; however, changes in skin sclerosis are suggested to reflect the systemic fibrotic process in SSc. Therefore, improvements in skin sclerosis may be a signal that disease progression has peaked. Thus far, no radical treatment has been developed for SSc. Therefore, the early identification of patients at high risk of serious major organ involvement and mortality, as well as early therapeutic intervention with diseasemodifying drugs within 5 years following the onset at the latest, are expected to reduce the maximum degree of fibrosis, leading to reductions in life-long functional disability (Fig. 4). TREATMENTS IN THE PAST AND AT PRESENT Over the past decades, D-penicillamine was used for the treatment of fibrosis in SSc. However, the efficacy of D-penicillamine 2016 Japanese Dermatological Association Figure 3. Proposed preliminary criteria for a very early diagnosis of systemic sclerosis (VEDOSS). 27 The presence of Raynaud s phenomenon, puffy fingers and antinuclear antibody positivity are identified as red flags that should raise suspicion of very early systemic sclerosis (SSc). Then, the suspicion is confirmed by the presence of abnormal nail fold capillaries and SSc-associated autoantibodies (anticentromere or anti-topoisomerase I antibody). Figure 4. Early therapeutic intervention with disease-modifying drugs reduces the maximum degree of fibrosis in patients with diffuse cutaneous systemic sclerosis. against SSc was virtually refuted by a double-blinded randomized controlled trial (RCT) in At present, several immunosuppressants are the primary therapeutic agents used for 49

5 K. Yanaba fibrosis in SSc worldwide. Some of these are briefly described below. Methotrexate Methotrexate (MTX), a synthetic folic acid analog, has a potent anti-inflammatory effect and is the only drug that is recommended by EULAR/EUSTAR for the treatment of skin involvement in SSc. 38 Two RCT have shown that MTX improves MRSS in patients with early dcssc. 39,40 In the first RCT, weekly MTX at a dose of 15 mg for 24 weeks showed a tendency to improve skin sclerosis in patients with SSc compared with placebo (P = 0.06), although patients with lcssc were included in this trial. 39 In the second RCT, oral weekly MTX at an initial dose of 10 mg or placebo was administrated to 71 patients with early dcssc for 12 months. 40 MTX appeared to ameliorate skin sclerosis compared with placebo (mean standard error of mean [SEM] MRSS, from to in the MTX group vs from to in the placebo group), although there was no significant difference (P = 0.17). Thus, MTX may be considered for the treatment of skin sclerosis in early dcssc. In contrast, the efficacy of MTX for other organ manifestations of SSc has not been proven by RCT thus far. Moreover, MTX can cause ILD; therefore, it is inappropriate to administrate MTX to SSc patients with ILD. Further studies are needed to verify the efficacy of MTX for SSc. Corticosteroids Presumably, corticosteroids are one of the most widely used drugs for the treatment of SSc, while few studies have been conducted to prove their efficacy. Generally, mg/day of oral prednisolone as the initial dose is administrated to patients with early dcssc. Oral prednisolone, with 20 mg as the initial dose, led to a 37% reduction in MRSS (mean SEM MRSS, from to ; P < 0.005) after 1 year of treatment in 23 patients with early dcssc, although no controltreated group was included. 41 However, prednisolone use (>15 mg/day) is suggested to be a risk factor for scleroderma renal crisis. 35 Cyclophosphamide Cyclophosphamide is a potent immunosuppressive agent that inhibits both humoral and cell-mediated immune responses. The efficacy of cyclophosphamide for ILD in SSc has been validated by RCT. 42 In the first RCT, oral cyclophosphamide at a dose of 1 2 mg/kg per day significantly but modestly improved pulmonary function compared with placebo at 12 months (P < 0.03); the adjusted mean absolute difference in the percentage of the predicted forced vital capacity (%FVC) was 2.5%. 42 In the second RCT, treatment with six infusions of cyclophosphamide at a dose of 600 mg/m 2 per month followed by oral azathioprine was compared with placebo. 43 At 12 months, the cyclophosphamide-treated group showed an improvement in %FVC compared with placebo (adjusted mean absolute difference, 4.2%), although the difference was not statistically significant (P = 0.08). Based on these studies, EULAR/EUSTAR recommends that cyclophosphamide should be considered for the treatment of ILD in SSc. 38 Furthermore, cyclophosphamide also significantly improved skin sclerosis in patients with dcssc treated with oral cyclophosphamide for 12 months compared with those treated with placebo (mean SEM MRSS, from to in the cyclophosphamide group vs to in the placebo group; P = ). 42 However, the efficacy of cyclophosphamide for ILD and skin sclerosis in SSc has been shown to be no longer apparent at 24 months of treatment. 44 Therefore, alternative therapeutic strategies are required following cyclophosphamide treatment. PROMISING TREATMENTS FOR FIBROSIS Several candidate therapies have been reported to be effective for the treatment of SSc in case reports or pilot studies, although their efficacy and safety have not fully validated by RCT. These are described below. Mycophenolate mofetil Mycophenolate mofetil (MMF), an inhibitor of lymphocyte proliferation, has been reported to be effective for the treatment of skin sclerosis and ILD in SSc, although no RCT have been published. In a retrospective study, the changes in MRSS in 98 patients with dcssc treated with MMF were compared with those from historical controls. 45 MMF treatment significantly improved skin sclerosis (mean decrease in MRSS SD, in MMF vs in D-penicillamine; P < 0.001) at 12 months. Furthermore, MMF has also been shown to improve %FVC at 12 months. 46,47 Thus, MMF may be a promising treatment for skin sclerosis and ILD in SSc, although RCT are necessary to verify its efficacy. Intravenous immunoglobulin Intravenous immunoglobulin (IVIG) is considered to have immunoregulatory activity, mainly through Fc receptor-related mechanisms, although its function has not been fully understood yet. IVIG is commonly used for the treatment of several autoimmune diseases; further, it has been shown to be efficacious against skin sclerosis in SSc. In a retrospective study, six cycles of IVIG treatment (2 g/kg per month) reduced MRSS in active dcssc (mean SD MRSS, from to ; P < ) at 24 months. 48 In contrast, a single cycle of IVIG (2 g/kg) did not show an improvement in MRSS at 12 weeks in an RCT of 63 patients with dcssc. 49 However, additional IVIG administration at 12 weeks significantly reduced MRSS at 60 weeks compared with a single course of IVIG (mean decrease in MRSS standard deviation [SD], vs ; P = 0.004), suggesting that repeated IVIG treatment may affect long-term improvement in skin sclerosis. Further studies are needed to confirm the efficacy of IVIG for SSc. B cell depletion Recently, numerous studies regarding the role of B cells in autoimmune diseases have been reported, and B cells have been recognized as therapeutic targets. B cells contribute to immune responses not only through antibody production but Japanese Dermatological Association

6 Treatment of fibrosis in systemic sclerosis also through antigen presentation, regulating T-cell activation and production of various cytokines. 50 Most patients with SSc have disease-specific autoantibodies and hypergammaglobulinemia. 51 CD19, a B-cell-specific cell surface molecule that defines signal thresholds critical for humoral immune responses and autoimmunity, is overexpressed on B cells from patients with SSc, 52 and a CD19 gene polymorphism is associated with SSc susceptibility. 53 In a murine model of SSc, B-cell depletion with anti-cd20 monoclonal antibody ameliorates the development of skin sclerosis and autoantibody production. 54 Thus, B cells appear to play an important role in the pathogenesis of SSc and can possibly be a therapeutic target. Thus far, the use of rituximab, a chimeric monoclonal antibody against human CD20, has been reported to be efficacious in both skin sclerosis and ILD in SSc by case reports, 55,56 open-label trials and one small-scale RCT. 62 In a case control study with 25 patients with severe dcssc (MRSS, >16), rituximab treatment significantly improved skin sclerosis (mean SEM MRSS, from to ; P = ) after 6 months (range, 5 9) of follow up. 60 Moreover, in nine SSc patients with ILD, rituximab prevented the reduction of %FVC (mean SEM %FVC, from to ; P = 0.5). 60 Consistently, in an open-label, uncontrolled study with 20 patients with dcssc, rituximab significantly reduced MRSS while preserving pulmonary function at 12 months. 61 Therefore, B-cell depletion therapy may be beneficial for SSc patients with severe skin sclerosis and ILD. Large-scale RCT to validate the efficacy of therapy targeting B-cell depletion are required. Anti-interleukin-6 receptor antibody Interleukin (IL)-6 is a pleiotropic pro-inflammatory cytokine that regulates the activation, proliferation and differentiation of various immune cells by binding to the IL-6 receptor. 63 Extensive studies have demonstrated that IL-6 plays a pivotal role in the pathogenesis of SSc. IL-6 expression is increased in the serum and skin of patients with early dcssc, and high serum IL-6 levels are associated with the severity of skin sclerosis and ILD as well as reduced survival Dermal and lung fibroblasts, dermal perivascular inflammatory infiltrates, T cells, B cells and natural killer cells from patients with SSc overproduce IL Moreover, IL-6 trans-signaling induces collagen synthesis in dermal fibroblasts from SSc patients. 68,73 Moreover, an IL6 gene polymorphism is known to be associated with SSc susceptibility. 74 In a murine model of SSc, loss or blockade of IL-6 or of the IL-6 receptor reduces the severity of skin and lung fibrosis. 75,76 These findings suggest that the blockade of IL-6 or the IL-6 receptor would be a promising target for the treatment of SSc. Consistently, tocilizumab, a humanized monoclonal antibody against the human IL-6 receptor, appeared to improve skin sclerosis and stabilize ILD in case reports. 77,78 RCT are necessary to validate the efficacy of tocilizumab in patients with SSc. Autologous hematopoietic stem cell transplantation Hematopoietic stem cells reside in the bone marrow and have the ability to differentiate into mature blood cell lineages, leading to immune system reconstitution. 79 Autologous hematopoietic stem cell transplantation (HSCT) has been shown to be effective 2016 Japanese Dermatological Association for patients with autoimmune diseases, including SSc, in whom conventional treatment has failed. 79 In a phase III RCT, 156 patients with early dcssc were randomized to receive either HSCT or 12 cycles of i.v. cyclophosphamide pulse treatment (750 mg/m 2 per month). 80 Compared with cyclophosphamide, HSCT markedly improved both skin sclerosis (mean change in MRSS SD, in the HSCT group vs in the cyclophosphamide group; P < 0.001) and ILD (mean change in %FVC SD, in the HSCT group vs in the cyclophosphamide group; P = 0.004) at 2 years of follow up. Furthermore, long-term event-free survival after 3 years was favorable with HSCT; however, treatmentrelated mortality in the first year was higher in the HSCT-treated group than in the cyclophosphamide-treated group (10.1% vs 0%, respectively). Thus, HSCT may be a promising treatment for patients with severe SSc at a high risk of serious major organ involvement and mortality, although it is essential to establish appropriate criteria for patient selection for HSCT. Rapamycin Rapamycin, a macrolide antibiotic, has been shown to have potent immunosuppressive effects. Rapamycin binds to FK- 506 binding protein 12, and the complex inhibits the function of the mammalian target of rapamycin that regulates cell proliferation, cytokine production 81 and collagen deposition. 82 Rapamycin has been shown to not only prevent fibrosis in both skin and lung but also inhibit autoantibody production in a murine model of SSc. 83 In a phase I, single-blinded, randomized, parallel trial of rapamycin versus MTX, rapamycin was equally efficacious as MTX for skin sclerosis without serious adverse events. 84 Thus, rapamycin may be an effective and safe drug for the treatment of SSc. Pirfenidone Pirfenidone, a pyridine with a simple chemical structure, is an antifibrotic agent, and has been approved for the treatment of idiopathic pulmonary fibrosis worldwide. 85 Pirfenidone inhibits the production of profibrotic cytokines, including TGF-b1 and platelet-derived growth factor, leading to attenuated collagen deposition. 85,86 Moreover, pirfenidone has also been shown to suppress pro-inflammatory cytokine production, such as that of tumor necrosis factor-a, IL-1b and IL In experimental models, pirfenidone has been shown to inhibit the progression of fibrosis in the lung 87,88 and liver. 89 Further, it has been reported that pirfenidone has a stabilizing effect on ILD in patients with SSc, although the efficacy of pirfenidone for SSc remains unclear. Imatinib mesylate Imatinib mesylate is a tyrosine kinase inhibitor that inhibits both c-abl, an important downstream signaling molecule of TGF-b, and the platelet-derived growth factor signaling pathway, which stimulates collagen production. 93 In a mouse model of bleomycin-induced lung fibrosis, imatinib mesylate was shown to prevent TGF-b-induced fibroblast proliferation and ECM gene expression, resulting in suppression of the severity of lung fibrosis. 94 Moreover, in mouse models of SSc, imatinib 51

7 K. Yanaba mesylate reportedly inhibited both TGF-b and platelet-derived growth factor signaling, leading to the suppression of skin fibrosis. 95,96 Although imatinib mesylate appears to be a promising option for the treatment of SSc based on the results of animal studies, its efficacy remains controversial. In a phase I/ IIa, open-label, pilot trial with 20 patients with SSc, imatinib mesylate improved both %FVC and MRSS (1.74% and 3.9 points, respectively) at 12 months, although only 12 out of 20 patients completed the study mainly due to the adverse effects of the drug. 97 In a phase II pilot study, 30 SSc patients with ILD who were unresponsive to cyclophosphamide were treated with imatinib mesylate for 6 months, and 26 patients completed the study; of these 26 patients (73%) showed improved or stabilized pulmonary function. In contrast, in a phase II RCT, imatinib mesylate administrated to 28 patients with SSc did not lead to a significant improvement in skin sclerosis at 6 months of therapy. 99 Further studies are needed to validate the safety and efficacy of imatinib mesylate for patients with SSc. FUTURE PERSPECTIVES Systemic sclerosis is considered to be a T-helper (Th)2 dominant disease, because serum levels of Th2 cytokines are elevated in patients with SSc, particularly in patients with early dcssc Th2 cells produce IL-4, IL-6, IL-13 and IL-33, which stimulate collagen synthesis. 103 In contrast, the serum levels of IL-12, a Th1 cytokine, are decreased in early SSc but are higher in late SSc, while persistent Th2 predominance is related to poor prognosis, 104 suggesting that a shift from Th2 to Th1 polarization is associated with an improvement of SSc. Therefore, approaches to promote Th1 polarization may be attractive therapeutic options. Transforming growth factor-b is also a potential target of fibrosis in SSc. The efficacy of antihuman TGF-b monoclonal antibody (CAT-192) against skin sclerosis in patients with dcssc was evaluated in a phase I/II RCT. 105 Unfortunately, the study did not show any efficacy in the treatment of skin sclerosis, although blockade of TGF-b had revealed an improvement in skin sclerosis in murine models of SSc. 106,107 This negative result may be due to insufficient blocking of TGF-b. Therefore, antibodies or chemicals that can block the TGF-b signaling pathway more efficiently may be promising options. Furthermore, it would be attractive to target vasculopathy along with autoimmunity in order to prevent fibrosis in the early stages of SSc. Nonetheless, early diagnosis prior to the development of organ involvement and positive therapeutic interventions are important measures for the optimal treatment of SSc. CONFLICT OF INTEREST: None declared. REFERENCES 1 Simeon CP, Armadans L, Fonollosa V et al. Mortality and prognostic factors in Spanish patients with systemic sclerosis. Rheumatology (Oxford) 2003; 42: Jacobsen S, Halberg P, Ullman S. Mortality and causes of death of 344 Danish patients with systemic sclerosis (scleroderma). Br J Rheumatol 1998; 37: Abu-Shakra M, Lee P. Mortality in systemic sclerosis: a comparison with the general population. J Rheumatol 1995; 22: Bryan C, Howard Y, Brennan P et al. Survival following the onset of scleroderma: results from a retrospective inception cohort study of the UK patient population. Br J Rheumatol 1996; 35: Tyndall AJ, Bannert B, Vonk M et al. Causes and risk factors for death in systemic sclerosis: a study from the EULAR Scleroderma Trials and Research (EUSTAR) database. Ann Rheum Dis 2010; 69: Ioannidis JP, Vlachoyiannopoulos PG, Haidich AB et al. Mortality in systemic sclerosis: an international meta-analysis of individual patient data. Am J Med 2005; 118: LeRoy EC, Black C, Fleischmajer R et al. Scleroderma (systemic sclerosis): classification, subsets and pathogenesis. J Rheumatol 1988; 15: Ho KT, Reveille JD. The clinical relevance of autoantibodies in scleroderma. Arthritis Res Ther 2003; 5: Cox SR, Walker JG, Coleman M et al. Isolated pulmonary hypertension in scleroderma. Intern Med J 2005; 35: Steen VD, Medsger TA Jr. Epidemiology and natural history of systemic sclerosis. Rheum Dis Clin North Am 1990; 16: Clements P, Lachenbruch P, Furst D et al. The course of skin involvement in systemic sclerosis over three years in a trial of chlorambucil versus placebo. Arthritis Rheum 1993; 36: Steen VD, Medsger TA Jr. Improvement in skin thickening in systemic sclerosis associated with improved survival. Arthritis Rheum 2001; 44: Shand L, Lunt M, Nihtyanova S et al. Relationship between change in skin score and disease outcome in diffuse cutaneous systemic sclerosis: application of a latent linear trajectory model. Arthritis Rheum 2007; 56: Suematsu M, Wakabayashi Y, Ishimura Y. Gaseous monoxides: a new class of microvascular regulator in the liver. Cardiovasc Res 1996; 32: Butler AR, Flitney FW, Williams DL. NO, nitrosonium ions, nitroxide ions, nitrosothiols and iron-nitrosyls in biology: a chemist s perspective. Trends Pharmacol Sci 1995; 16: D Angelo WA, Fries JF, Masi AT et al. Pathologic observations in systemic sclerosis (scleroderma). A study of fifty-eight autopsy cases and fifty-eight matched controls. Am J Med 1969; 46: Fleischmajer R, Perlish JS, Reeves JRT. Cellular infiltrates in scleroderma skin. Arthritis Rheum 1977; 20: Roumm AD, Whiteside TL, Medsger TA Jr et al. Lymphocytes in the skin of patients with progressive systemic sclerosis. Quantification, subtyping, and clinical correlations. Arthritis Rheum 1984; 27: Gilbane AJ, Denton CP, Holmes AM. Scleroderma pathogenesis: a pivotal role for fibroblasts as effector cells. Arthritis Res Ther 2013; 15: Yazawa N, Fujimoto M, Tamaki K. Recent advances on pathogenesis and therapies in systemic sclerosis. Clin Rev Allergy Immunol 2007; 33: Kawakami T, Ihn H, Xu W et al. Increased expression of TGF-b receptors by scleroderma fibroblasts: evidence for contribution of autocrine TGF-b signaling to scleroderma phenotype. J Invest Dermatol 1998; 110: Preliminary criteria for the classification of systemic sclerosis (scleroderma). Subcommittee for Scleroderma Criteria of the American Rheumatism. Association Diagnostic and Therapeutic Criteria Committee. Arthritis Rheum 1980; 23: Lonzetti LS, Joyal F, Raynauld JP et al. Updating the American College of Rheumatology preliminary classification criteria for Japanese Dermatological Association

8 Treatment of fibrosis in systemic sclerosis systemic sclerosis: addition of severe nailfold capillaroscopy abnormalities markedly increases the sensitivity for limited scleroderma. Arthritis Rheum 2001; 44: van den Hoogen F, Khanna D, Fransen J et al classification criteria for systemic sclerosis: an American College of Rheumatology/European League against Rheumatism collaborative initiative. Arthritis Rheum 2013; 65: van den Hoogen F, Khanna D, Fransen J et al classification criteria for systemic sclerosis: an American college of rheumatology/european league against rheumatism collaborative initiative. Ann Rheum Dis 2013; 72: Koenig M, Joyal F, Fritzler MJ et al. Autoantibodies and microvascular damage are independent predictive factors for the progression of Raynaud s phenomenon to systemic sclerosis: a twentyyear prospective study of 586 patients, with validation of proposed criteria for early systemic sclerosis. Arthritis Rheum 2008; 58: Avouac J, Fransen J, Walker UA et al. Preliminary criteria for the very early diagnosis of systemic sclerosis: results of a Delphi Consensus Study from EULAR Scleroderma Trials and Research Group. Ann Rheum Dis 2011; 70: Minier T, Guiducci S, Bellando-Randone S et al. Preliminary analysis of the very early diagnosis of systemic sclerosis (VEDOSS) EU- STAR multicentre study: evidence for puffy fingers as a pivotal sign for suspicion of systemic sclerosis. Ann Rheum Dis 2014; 73: Bruni C, Guiducci S, Bellando-Randone S et al. Digital ulcers as a sentinel sign for early internal organ involvement in very early systemic sclerosis. Rheumatology (Oxford) 2015; 54: Al-Dhaher FF, Pope JE, Ouimet JM. Determinants of morbidity and mortality of systemic sclerosis in Canada. Semin Arthritis Rheum 2010; 39: Czirjak L, Kumanovics G, Varju C et al. Survival and causes of death in 366 Hungarian patients with systemic sclerosis. Ann Rheum Dis 2008; 67: Nihtyanova SI, Schreiber BE, Ong VH et al. Prediction of pulmonary complications and long-term survival in systemic sclerosis. Arthritis Rheumatol 2014; 66: Clements PJ, Hurwitz EL, Wong WK et al. Skin thickness score as a predictor and correlate of outcome in systemic sclerosis: highdose versus low-dose penicillamine trial. Arthritis Rheum 2000; 43: Perera A, Fertig N, Lucas M et al. Clinical subsets, skin thickness progression rate, and serum antibody levels in systemic sclerosis patients with anti-topoisomerase I antibody. Arthritis Rheum 2007; 56: DeMarco PJ, Weisman MH, Seibold JR et al. Predictors and outcomes of scleroderma renal crisis: the high-dose versus low-dose D-penicillamine in early diffuse systemic sclerosis trial. Arthritis Rheum 2002; 46: Domsic RT, Rodriguez-Reyna T, Lucas M et al. Skin thickness progression rate: a predictor of mortality and early internal organ involvement in diffuse scleroderma. Ann Rheum Dis 2011; 70: Clements PJ, Furst DE, Wong WK et al. High-dose versus lowdose D-penicillamine in early diffuse systemic sclerosis: analysis of a two-year, double-blind, randomized, controlled clinical trial. Arthritis Rheum 1999; 42: Kowal-Bielecka O, Landewe R, Avouac J et al. EULAR recommendations for the treatment of systemic sclerosis: a report from the EULAR Scleroderma Trials and Research group (EUSTAR). Ann Rheum Dis 2009; 68: van den Hoogen FH, Boerbooms AM, Swaak AJ et al. Comparison of methotrexate with placebo in the treatment of systemic sclerosis: a 24 week randomized double-blind trial, followed by a 24 week observational trial. Br J Rheumatol 1996; 35: Pope JE, Bellamy N, Seibold JR et al. A randomized, controlled trial of methotrexate versus placebo in early diffuse scleroderma. Arthritis Rheum 2001; 44: Takehara K. Treatment of early diffuse cutaneous systemic sclerosis patients in Japan by low-dose corticosteroids for skin involvement. Clin Exp Rheumatol 2004; 22: S87 S Tashkin DP, Elashoff R, Clements PJ et al. Cyclophosphamide versus placebo in scleroderma lung disease. N Engl J Med 2006; 354: Hoyles RK, Ellis RW, Wellsbury J et al. A multicenter, prospective, randomized, double-blind, placebo-controlled trial of corticosteroids and intravenous cyclophosphamide followed by oral azathioprine for the treatment of pulmonary fibrosis in scleroderma. Arthritis Rheum 2006; 54: Tashkin DP, Elashoff R, Clements PJ et al. Effects of 1-year treatment with cyclophosphamide on outcomes at 2 years in scleroderma lung disease. Am J Respir Crit Care Med 2007; 176: Le EN, Wigley FM, Shah AA et al. Long-term experience of mycophenolate mofetil for treatment of diffuse cutaneous systemic sclerosis. Ann Rheum Dis 2011; 70: Koutroumpas A, Ziogas A, Alexiou I et al. Mycophenolate mofetil in systemic sclerosis-associated interstitial lung disease. Clin Rheumatol 2010; 29: Gerbino AJ, Goss CH, Molitor JA. Effect of mycophenolate mofetil on pulmonary function in scleroderma-associated interstitial lung disease. Chest 2008; 133: Poelman CL, Hummers LK, Wigley FM et al. Intravenous immunoglobulin may be an effective therapy for refractory, active diffuse cutaneous systemic sclerosis. J Rheumatol 2015; 42: Takehara K, Ihn H, Sato S. A randomized, double-blind, placebocontrolled trial: intravenous immunoglobulin treatment in patients with diffuse cutaneous systemic sclerosis. Clin Exp Rheumatol 2013; 31: Yanaba K, Bouaziz JD, Matsushita T et al. B-lymphocyte contributions to human autoimmune disease. Immunol Rev 2008; 223: Famularo G, Giacomelli R, Alesse E et al. Polyclonal B lymphocyte activation in progressive systemic sclerosis. J Clin Lab Immunol 1989; 29: Sato S, Hasegawa M, Fujimoto M et al. Quantitative genetic variation in CD19 expression correlates with autoimmunity. J Immunol 2000; 165: Tsuchiya N, Kuroki K, Fujimoto M et al. Association of a functional CD19 polymorphism with susceptibility to systemic sclerosis. Arthritis Rheum 2004; 50: Hasegawa M, Hamaguchi Y, Yanaba K et al. B-lymphocyte depletion reduces skin fibrosis and autoimmunity in the tight-skin mouse model for systemic sclerosis. Am J Pathol 2006; 169: Sumida H, Asano Y, Tamaki Z et al. Successful experience of rituximab therapy for systemic sclerosis-associated interstitial lung disease with concomitant systemic lupus erythematosus. J Dermatol 2014; 41: Daoussis D, Liossis SN, Tsamandas AC et al. 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: Smith V, Van Praet JT, Vandooren B et al. Rituximab in diffuse cutaneous systemic sclerosis: an open-label clinical and histopathological study. Ann Rheum Dis 2010; 69: Smith V, Piette Y, van Praet JT et al. Two-year results of an open pilot study of a 2-treatment course with rituximab in patients with early systemic sclerosis with diffuse skin involvement. J Rheumatol 2013; 40: Bosello S, De Santis M, Lama G et al. B cell depletion in diffuse progressive systemic sclerosis: safety, skin score modification and IL-6 modulation in an up to thirty-six months follow-up open-label trial. Arthritis Res Ther 2010; 12: R Jordan S, Distler JH, Maurer B et al. Effects and safety of rituximab in systemic sclerosis: an analysis from the European Scleroderma Trial and Research (EUSTAR) group. Ann Rheum Dis 2015; 74: Japanese Dermatological Association 53

9 K. Yanaba 61 Bosello SL, De Luca G, Rucco M et al. Long-term efficacy of B cell depletion therapy on lung and skin involvement in diffuse systemic sclerosis. Semin Arthritis Rheum 2015; 44: Daoussis D, Liossis SN, Tsamandas AC et al. Experience with rituximab in scleroderma: results from a 1-year, proof-of-principle study. Rheumatology (Oxford) 2010; 49: Hunter CA, Jones SA. IL-6 as a keystone cytokine in health and disease. Nat Immunol 2015; 16: De Santis M, Bosello S, La Torre G et al. Functional, radiological and biological markers of alveolitis and infections of the lower respiratory tract in patients with systemic sclerosis. Respir Res 2005; 6: De Lauretis A, Sestini P, Pantelidis P et al. Serum interleukin 6 is predictive of early functional decline and mortality in interstitial lung disease associated with systemic sclerosis. J Rheumatol 2013; 40: Sato S, Hasegawa M, Takehara K. Serum levels of interleukin-6 and interleukin-10 correlate with total skin thickness score in patients with systemic sclerosis. J Dermatol Sci 2001; 27: Hasegawa M, Sato S, Fujimoto M et al. Serum levels of interleukin 6 (IL-6), oncostatin M, soluble IL-6 receptor, and soluble gp130 in patients with systemic sclerosis. J Rheumatol 1998; 25: Khan K, Xu S, Nihtyanova S et al. Clinical and pathological significance of interleukin 6 overexpression in systemic sclerosis. Ann Rheum Dis 2012; 71: Matsushita T, Hasegawa M, Yanaba K et al. Elevated serum BAFF levels in patients with systemic sclerosis: enhanced BAFF signaling in systemic sclerosis B lymphocytes. Arthritis Rheum 2006; 54: Kondo K, Okada T, Matsui T et al. Establishment and characterization of a human B cell line from the lung tissue of a patient with scleroderma; extraordinary high level of IL-6 secretion by stimulated fibroblasts. Cytokine 2001; 13: Feghali CA, Bost KL, Boulware DW et al. Mechanisms of pathogenesis in scleroderma. I. Overproduction of interleukin 6 by fibroblasts cultured from affected skin sites of patients with scleroderma. J Rheumatol 1992; 19: Muangchan C, Pope JE. Interleukin 6 in systemic sclerosis and potential implications for targeted therapy. J Rheumatol 2012; 39: Hugle T, O Reilly S, Simpson R et al. Tumor necrosis factor-costimulated T lymphocytes from patients with systemic sclerosis trigger collagen production in fibroblasts. Arthritis Rheum 2013; 65: Cenit MC, Simeon CP, Vonk MC et al. Influence of the IL6 gene in susceptibility to systemic sclerosis. J Rheumatol 2012; 39: Yoshizaki A, Yanaba K, Ogawa A et al. Immunization with DNA topoisomerase I and Freund s complete adjuvant induces skin and lung fibrosis and autoimmunity via interleukin-6 signaling. Arthritis Rheum 2011; 63: Kitaba S, Murota H, Terao M et al. Blockade of interleukin-6 receptor alleviates disease in mouse model of scleroderma. Am J Pathol 2012; 180: Shima Y, Kuwahara Y, Murota H et al. The skin of patients with systemic sclerosis softened during the treatment with anti-il-6 receptor antibody tocilizumab. Rheumatology (Oxford) 2010; 49: Fernandes das Neves M, Oliveira S, Amaral MC et al. Treatment of systemic sclerosis with tocilizumab. Rheumatology (Oxford), 2015; 54: Cipriani P, Ruscitti P, Giacomelli R. Stem cell therapies for systemic sclerosis. Br J Haematol 2015; 168: van Laar JM, Farge D, Sont JK et al. Autologous hematopoietic stem cell transplantation vs intravenous pulse cyclophosphamide in diffuse cutaneous systemic sclerosis: a randomized clinical trial. JAMA 2014; 311: Young DA, Nickerson-Nutter CL. mtor beyond transplantation. Curr Opin Pharmacol 2005; 5: Tamaki Z, Asano Y, Kubo M et al. Effects of the immunosuppressant rapamycin on the expression of human a2(i) collagen and matrix metalloproteinase 1 genes in scleroderma dermal fibroblasts. J Dermatol Sci 2014; 74: Yoshizaki A, Yanaba K, Yoshizaki A et al. Treatment with rapamycin prevents fibrosis in tight-skin and bleomycin-induced mouse models of systemic sclerosis. Arthritis Rheum 2010; 62: Su TI, Khanna D, Furst DE et al. Rapamycin versus methotrexate in early diffuse systemic sclerosis: results from a randomized, single-blind pilot study. Arthritis Rheum 2009; 60: Carter NJ. Pirfenidone: in idiopathic pulmonary fibrosis. Drugs 2011; 71: Saito M, Yamazaki M, Maeda T et al. Pirfenidone suppresses keloid fibroblast-embedded collagen gel contraction. Arch Dermatol Res 2012; 304: Kakugawa T, Mukae H, Hayashi T et al. Pirfenidone attenuates expression of HSP47 in murine bleomycin-induced pulmonary fibrosis. Eur Respir J 2004; 24: Iyer SN, Margolin SB, Hyde DM et al. Lung fibrosis is ameliorated by pirfenidone fed in diet after the second dose in a three-dose bleomycin-hamster model. Exp Lung Res 1998; 24: Di Sario A, Bendia E, Macarri G et al. The anti-fibrotic effect of pirfenidone in rat liver fibrosis is mediated by downregulation of procollagen a1(i), TIMP-1 and MMP-2. Dig Liver Dis 2004; 36: Nagai S, Hamada K, Shigematsu M et al. Open-label compassionate use one year-treatment with pirfenidone to patients with chronic pulmonary fibrosis. Intern Med 2002; 41: Udwadia ZF, Mullerpattan JB, Balakrishnan C et al. Improved pulmonary function following pirfenidone treatment in a patient with progressive interstitial lung disease associated with systemic sclerosis. Lung India 2015; 32: Miura Y, Saito T, Fujita K et al. Clinical experience with pirfenidone in five patients with scleroderma-related interstitial lung disease. Sarcoidosis Vasc Diffuse Lung Dis 2014; 31: Bournia VK, Evangelou K, Sfikakis PP. Therapeutic inhibition of tyrosine kinases in systemic sclerosis: a review of published experience on the first 108 patients treated with imatinib. Semin Arthritis Rheum, 2013; 42: Daniels CE, Wilkes MC, Edens M et al. Imatinib mesylate inhibits the profibrogenic activity of TGF-b and prevents bleomycin-mediated lung fibrosis. J Clin Invest 2004; 114: Distler JH, Jungel A, Huber LC et al. Imatinib mesylate reduces production of extracellular matrix and prevents development of experimental dermal fibrosis. Arthritis Rheum 2007; 56: Akhmetshina A, Venalis P, Dees C et al. Treatment with imatinib prevents fibrosis in different preclinical models of systemic sclerosis and induces regression of established fibrosis. Arthritis Rheum 2009; 60: Khanna D, Saggar R, Mayes MD et al. A one-year, phase I/IIa, open-label pilot trial of imatinib mesylate in the treatment of systemic sclerosis-associated active interstitial lung disease. Arthritis Rheum 2011; 63: Fraticelli P, Gabrielli B, Pomponio G et al. Low-dose oral imatinib in the treatment of systemic sclerosis interstitial lung disease unresponsive to cyclophosphamide: a phase II pilot study. Arthritis Res Ther 2014; 16: R Prey S, Ezzedine K, Doussau A et al. Imatinib mesylate in scleroderma-associated diffuse skin fibrosis: a phase II multicentre randomized double-blinded controlled trial. Br J Dermatol 2012; 167: Hasegawa M, Fujimoto M, Kikuchi K et al. Elevated serum levels of interleukin 4 (IL-4), IL-10, and IL-13 in patients with systemic sclerosis. J Rheumatol 1997; 24: Yanaba K, Yoshizaki A, Asano Y et al. Serum IL-33 levels are raised in patients with systemic sclerosis: association with extent Japanese Dermatological Association