Unprecedented success of rituximab therapy for prednisolone- and immunosuppressant-resistant systemic sclerosis-associated interstitial lung disease

B cell depletion inhibits fibrosis via suppressing pro-fibrotic macrophage differentiation in a mouse model of systemic sclerosis

OBJECTIVE

We investigated the effect of B cell depletion on fibrosis in systemic sclerosis (SSc) and its mechanism of action.

METHODS

Bleomycin-induced SSc (BLM-SSc) model mice were treated with anti-CD20 antibody, and skin and lung fibrosis was evaluated histopathologically. T cells and macrophages were co-cultured with B cells, and the effect of B cells on their differentiation was assessed by flow cytometry. We also co-cultured B cells and monocytes from SSc patients and analyzed the correlation between fibrosis and pro-fibrotic macrophage induction by B cells.

RESULTS

B cell depletion inhibited fibrosis in BLM-SSc mice. B cells from BLM-SSc mice increased pro-inflammatory cytokine producing T cells in co-culture. In BLM-SSc mice, B cell depletion before BLM treatment (pre-depletion) inhibited fibrosis more strongly than B cell depletion after BLM treatment (post-depletion). However, the frequencies of pro-inflammatory T cells were lower in the post-depletion group than in the pre-depletion group. This discrepancy suggests that the effect of B cell depletion on fibrosis cannot be explained by its effect on T cell differentiation. On the other hand, pro-fibrotic macrophages were markedly decreased in the pre-depletion group than in the post-depletion group. Furthermore, B cells from BLM-SSc mice increased pro-fibrotic macrophage differentiation in co-culture. In SSc patients, the extent of pro-fibrotic macrophage induction by B cells correlated with the severity of fibrosis.

CONCLUSION

These findings suggest that B cell depletion inhibits tissue fibrosis via suppressing pro-fibrotic macrophage differentiation in BLM-SSc mice, providing a new rationale for B cell depletion therapy in SSc.

Relevance of immunomodulatory therapy for interstitial lung disease in systemic sclerosis

Systemic sclerosis is an autoimmune disease that prominently leads to skin and tissue fibrosis. The efficacy of autologous stem cell transplantation not only attests to the autoimmune pathophysiology for systemic sclerosis, but also for interstitial lung disease as its most frequent manifestation of fatal organ involvement. Accordingly, a variety of immunomodulatory therapies were tried on patients with systemic sclerosis-interstitial lung disease. Until very recently, all of these therapeutic approaches constituted off-label treatment for systemic sclerosis, given that neither of these therapies was approved by the United States Food and Drug Administration (FDA) or the European Medicines Agency. For tocilizumab, this has now changed with FDA approval in March 2021. Already 2020, nintedanib, which is an antifibrotic drug that does not target autoimmunity, became the first approved drug for interstitial lung disease in systemic sclerosis. The present review analyzes the evidence for immunomodulatory treatment of systemic sclerosis-associated interstitial lung disease. The review focuses on randomized controlled trials, which provides evidence for the effects of drugs such as cyclophosphamide, mycophenolate, rituximab and tocilizumab.

Rituximab in the Treatment of Interstitial Lung Disease Associated with Autoimmune Diseases: Experience from a Single Referral Center and Literature Review

In the present study, we aimed to report our experience with rituximab (RTX) in the treatment of patients with ILD associated with AD (AD-ILD) at a single center. For this purpose, clinical characteristics, radiological findings, and pulmonary function tests (PFTs) of RTX-treated AD-ILD-patients seen from May 2016 until March 2020 at a referral center for individuals with ILD were retrospectively reviewed. Additionally, an updated literature review was conducted. A total of 26 patients (mean age 58.3 ± 11.1 years at ILD diagnosis) was included. The most common ADs related to ILD were systemic sclerosis, idiopathic inflammatory myositis (including anti-synthetase syndrome) and rheumatoid arthritis. Non-specific interstitial pneumonia (n = 12) and usual interstitial pneumonia (n = 11) were the predominant radiological patterns. The sustained improvement in PFTs was observed from the start of RTX, with a statistically significant increase in DLCO from basal to one year after RTX (mean + 4.2%, p = 0.024). Overall, there were no differences when comparing PFT outcome according to the radiological pattern or the specific type of AD. In conclusion, RTX constitutes a good therapeutic option to preserve lung function in patients with AD-ILD, regardless of the radiological pattern or the underlying AD.

Expert Perspectives On Clinical Challenges: Expert Perspectives: Challenges in Scleroderma

You are consulted to evaluate a 56-year-old woman with known Raynaud's phenomenon, finger swelling of several; months' duration, and new hypertension with a blood pressure of 160/100 mm/Hg. She also reports progressive shortness of breath. Physical examination reveals telangiectasias, sclerodactyly, and proximal skin sclerosis (thick shiny skin on the chest and upper arms), and bibasilar crackles are found on chest examination. Laboratory tests reveal evidence of microangiopathic hemolytic anemia, thrombocytopenia, and elevation of the serum creatinine level (previously normal), and chest computed tomography shows evidence of ground-glass opacification in both lower lung fields.

Connective Tissue Disease-Associated Interstitial Lung Disease: Evaluation and Management

Interstitial lung disease is common among patients with connective tissue disease and is an important contributor to morbidity and mortality. Infection and drug toxicity must always be excluded as the cause of radiographic findings. Immunosuppression remains a mainstay of therapy despite few controlled trials supporting its use. When a decision regarding therapy initiation is made, considerations include an assessment of disease severity as well as a determination of the rate of progression. Because patients may have extrathoracic disease activity, a multidisciplinary approach is crucial and should include supportive and nonpharmacologic management strategies.

Safety and efficacy of Rituximab in systemic sclerosis: A systematic review and meta-analysis

PURPOSE

Rituximab is widely prescribed to treat systemic sclerosis (SSc) by the depletion of pathogenic B cells. Nonetheless, the clinical benefit of Rituximab in SSc remains contentious. This meta-analysis was conducted to systematically evaluate the safety and efficacy profile of Rituximab in SSc patients.

PATIENTS AND METHODS

We performed a systematic online query in PubMed, Cochrane, and Web of Science. The available studies on the use of Rituximab in SSc patients were comprehensively reviewed and investigated.

RESULTS

In total, 14 studies, including 597 participants, were analyzed. Pooled results showed the long-term improvement in the modified Rodnan skin score (mRSS) for skin function (ΔmRSS: 7.00 at 6 months, 9.70 at 12 months, and 10.93 at 24 months), while forced vital capacity (FVC) (ΔFVC: -0.69 at 6 months, -2.62 at 12 months, and -0.67 at 24 months) and diffusing capacity of the lungs for carbon monoxide (DLCO) (ΔDLCO: -2.39 at 6 months, -3.28 at 12 months, and -0.79 at 24 months) for lung function remained stable in SSc patients after Rituximab treatment. The rate of Rituximab-related adverse events was 12% in the pooled results.

CONCLUSION

The pooled results of this meta-analysis indicated that Rituximab is well tolerated, and it is able to improve cutaneous function and stabilize pulmonary function in SSc patients.

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.

Rituximab treatment in patients with systemic sclerosis and interstitial lung disease

There is increasing interest in rituximab (RTX) as an alternative to cyclophosphamide for the treatment of interstitial lung diseases (ILDs) associated with systemic sclerosis (SSc). However, no report has addressed its efficacy in Saudi patients with SSc-ILD. To assess the efficacy of RTX treatment in Saudi patients with SSc-ILD, hospital records were reviewed between 2013 and 2016. Four female patients received at least 4 cycles of RTX (I cycle, consisting of two infusions of 1000 mg 2 weeks apart). Pulmonary function tests (PFTs) and chest high-resolution computed tomography (HRCT) were performed before and after treatment to assess the response. HRCT revealed improvement in one patient, stable disease in two patients, and worsening in one patient. Moreover, RTX prevented the further decline of forced vital capacity significantly in PFT. These results provide further evidence that RTX is an effective treatment for SSc-ILD.