Increased expression of 2'5'oligoadenylate synthetase and double-stranded RNA dependent protein kinase messenger RNAs on affected skin of systemic sclerosis patients

Type I IFNs Regulate Inflammation, Vasculopathy, and Fibrosis in Chronic Cutaneous Graft-versus-Host Disease

Type I IFNs play a critical role in the immune response to viral infection and may also drive autoimmunity through modulation of monocyte maturation and promotion of autoreactive lymphocyte survival. Recent demonstrations of type I IFN gene signatures in autoimmune diseases, including scleroderma, led us to investigate the pathological role of IFNs in a preclinical model of sclerodermatous graft-versus-host disease. Using a neutralizing Ab against the type I IFN receptor IFNAR1, we observed a marked reduction in dermal inflammation, vasculopathy, and fibrosis compared with that seen in the presence of intact IFNAR1 signaling. The ameliorative effects of IFNAR1 blockade were restricted to the skin and were highly associated with inhibition of chronic vascular injury responses and not due to the inhibition of the T or B cell alloresponse. Inhibition of IFNAR1 normalized the overexpression of IFN-inducible genes in graft-versus-host disease skin and markedly reduced dermal IFN-α levels. Depletion of plasmacytoid dendritic cells, a major cellular source of type I IFNs, did not reduce the severity of fibrosis or type I IFN gene signature in the skin. Taken together, these studies demonstrate an important role for type I IFN in skin fibrosis, and they provide a rationale for IFNAR1 inhibition in scleroderma.

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.

Differential upregulation of human 2'5'OAS genes on systemic sclerosis: Detection of increased basal levels of OASL and OAS2 genes through a qPCR based assay

2'5'OAS are template-independent RNA polymerases with antiviral activity and important to homeostasis maintenance. Here we have developed quantitative PCR (qPCR) reactions for the detection of each individual 2'5'OAS human gene and used them to evaluate these gene levels in systemic sclerosis patients cells. The method was efficient for quantification of 2'5'OAS genes on human cells after interferon (IFN) treatment, and revealed that primary cells from patients with systemic sclerosis have increased basal levels of OASL and OAS2 genes. When treated, patients cells are able to induce all four 2'5'OAS genes. Our hypothesis is that abnormally circulating type I IFNs on the disease could be establishing a desensitized state on patients cells, making them refractory to subsequent IFN doses, and that OASL and OAS2 genes upregulation may be due to an IFN-independent stimulus. Further characterizing the biological activities of these genes, their induction pathways and their regulatory functions can lead to better understanding of systemic sclerosis molecular mechanisms and of their biological activities.

Pharmacogenomics and translational simulations to bridge indications for an anti-interferon-α receptor antibody

A type I interferon (IFN) gene signature shared by systemic lupus erythematous (SLE) and systemic sclerosis (SSc) was used to evaluate an anti-type I IFN-α receptor (IFN-αR) monoclonal antibody, MEDI-546, in a phase I trial in SSc. MEDI-546 suppressed IFN signature in blood and skin of SSc patients in a dose-dependent manner. To bridge clinical indications to SLE, we developed a model incorporating (i) pharmacokinetics (PK) and pharmacodynamics (PD) in SSc patients, (ii) internalization kinetics of MEDI-546/IFN-αR complex, and (iii) the different IFN signatures between SSc and SLE. Simulations predicted that i.v. administration of MEDI-546 at 300- or 1,000-mg monthly doses could suppress IFN signature in blood to levels of healthy subjects in 53 and 68% of SLE patients, respectively. An innovative approach utilizing a novel biomarker characterized the PD of MEDI-546 by modeling and simulation and allowed rapid progression of MEDI-546 from a phase I study in SSc to a randomized, multiple-dose phase II trial.

Type I interferons in Sjögren's syndrome

Sjögren's syndrome is a chronic autoimmune disease characterized by lymphocytic infiltration of the salivary and lachrymal glands resulting in dry eyes and mouth. Genetic predisposition, pathogenic infections and hormones have been implicated in the pathogenesis of the disease. Studies in the last several years have revealed marked over-expression of the type I interferon (IFN)-inducible genes in the peripheral blood and salivary glands of patients with Sjögren's syndrome. The expression of the type I IFN-inducible genes in Sjögren's syndrome also positively correlates to titers of anti-Ro and anti-La autoantibodies, which are typical for this disease. Plasmacytoid dendritic cells (pDC) are the major source of type I IFN production and activated pDC are detected in minor salivary gland biopsies from patients with primary Sjögren's syndrome. In addition, polymorphisms in genes important both for the production and response to type I IFN are associated to increased risk for Sjögren's syndrome. Because type I IFN bears a variety of biological functions, such as defense against viral infections and activation of the immune system, these results suggest that the type I IFN system has an important role in the pathogenesis of Sjögren's syndrome. A variety of mechanisms causing an activation of the type I IFN system are discussed in this review. Given the pivotal role of type I IFN in the disease process, therapeutic interventions targeting the type I IFN signaling pathway have the potential to benefit the patients with elevated type I IFN status and such hypothesis needs to be carefully evaluated in clinical development.

Basal Activation of Type I Interferons (Alpha2 and Beta) and 2'5'OAS Genes: Insights into Differential Expression Profiles of Interferon System Components in Systemic Sclerosis

Objective. Systemic sclerosis (SSc) is a complex autoimmune disease in which interferons (IFNs) may play an essential role. We hypothesized that type I and III IFNs may be found in increased levels in patients and be responsible for SSc autoimmune status. Methods. Type I and III IFN and ISG basal expression profiles were measured by qPCR using RNA from PBMCs of patients and controls . Results. Type I IFNs are increased in SSc patients, while no induction of type III IFNs was detected. This induction cannot be related to IRF7, since no upregulation of this gene was seen on patients. Of the ISGs tested, 2′5′OAS levels were increased in patients, while 6–16 and MxA levels were not. Conclusions. While there is no indication of type III IFN induction, increased levels of type I IFNs may lead to abnormal regulation of ISGs that can be responsible for immune system alterations described for SSc.

Interferons and scleroderma-a new clue to understanding the pathogenesis of scleroderma?

Scleroderma or systemic sclerosis (SSc) is a complex disease characterized by vasculopathy and deregulated immune and fibroblast activation. The resulting excessive production of collagens and other extracellular matrix proteins by fibroblasts as well as the inflammatory response leads to the development of scleroderma. Recently, some emerging data have been showing a possible link between the type I and II interferons (IFNs) and SSc pathogenesis. IFNs are well-known immunomodulators and inhibitors of collagen production. However, IFN therapy also has been implicated in the development or exacerbation of several autoimmune diseases, including SSc. Some studies also showed an increase mRNA and protein levels of IFNs and several interferon stimulated genes in cells and tissues from SSc patients. In this review we discuss about a possible role for IFNs in SSc development and pathogenesis.