Flavia V. Castelino

Amelioration of dermal fibrosis by genetic deletion or pharmacologic antagonism of lysophosphatidic acid receptor 1 in a mouse model of scleroderma.

OBJECTIVE Scleroderma (systemic sclerosis [SSc]), is characterized by progressive multiorgan fibrosis. We recently implicated lysophosphatidic acid (LPA) in the pathogenesis of pulmonary fibrosis. The purpose of the present study was to investigate the roles of LPA and two of its receptors, LPA₁ and LPA₂, in dermal fibrosis in a mouse model of SSc. METHODS Wild type (WT), and LPA₁-knockout (KO) and LPA₂-KO mice were injected subcutaneously with bleomycin or phosphate buffered saline (PBS) once daily for 28 days. Dermal thickness, collagen content, and numbers of cells positive for α-smooth muscle actin (α-SMA) or phospho-Smad2 were determined in bleomycin-injected and PBS-injected skin. In separate experiments, a novel selective LPA₁ antagonist AM095 or vehicle alone was administered by oral gavage to C57BL/6 mice that were challenged with 28 daily injections of bleomycin or PBS. AM095 or vehicle treatments were initiated concurrently with, or 7 or 14 days after, the initiation of bleomycin and PBS injections and continued to the end of the experiments. Dermal thickness and collagen content were determined in injected skin. RESULTS The LPA₁ -KO mice were markedly resistant to bleomycin-induced increases in dermal thickness and collagen content, whereas the LPA₂-KO mice were as susceptible as the WT mice. Bleomycin-induced increases in dermal α-SMA+ and phospho-Smad2+ cells were abrogated in LPA₁-KO mice. Pharmacologic antagonism of LPA₁ with AM095 significantly attenuated bleomycin-induced dermal fibrosis when administered according to either a preventive regimen or two therapeutic regimens. CONCLUSION These results suggest that LPA/LPA₁ pathway inhibition has the potential to be an effective new therapeutic strategy for SSc, and that LPA₁ is an attractive pharmacologic target in dermal fibrosis.

Interstitial lung disease in connective tissue diseases: evolving concepts of pathogenesis and management

Interstitial lung disease (ILD) is a challenging clinical entity associated with multiple connective tissue diseases, and is a significant cause of morbidity and mortality. Effective therapies for connective tissue disease-associated interstitial lung disease (CTD-ILD) are still lacking. Multidisciplinary clinics dedicated to the early diagnosis and improved management of patients with CTD-ILD are now being established. There is rapid progress in understanding and identifying the effector cells, the proinflammatory and profibrotic mediators, and the pathways involved in the pathogenesis of CTD-ILD. Serum biomarkers may provide new insights as risk factors for pulmonary fibrosis and as measures of disease progression. Despite these recent advances, the management of patients with CTD-ILD remains suboptimal. Further studies are therefore urgently needed to better understand these conditions, and to develop effective therapeutic interventions.

Connective tissue disease related interstitial lung diseases and idiopathic pulmonary fibrosis: provisional core sets of domains and instruments for use in clinical trials

Rationale Clinical trial design in interstitial lung diseases (ILDs) has been hampered by lack of consensus on appropriate outcome measures for reliably assessing treatment response. In the setting of connective tissue diseases (CTDs), some measures of ILD disease activity and severity may be confounded by non-pulmonary comorbidities. Methods The Connective Tissue Disease associated Interstitial Lung Disease (CTD-ILD) working group of Outcome Measures in Rheumatology—a non-profit international organisation dedicated to consensus methodology in identification of outcome measures—conducted a series of investigations which included a Delphi process including >248 ILD medical experts as well as patient focus groups culminating in a nominal group panel of ILD experts and patients. The goal was to define and develop a consensus on the status of outcome measure candidates for use in randomised controlled trials in CTD-ILD and idiopathic pulmonary fibrosis (IPF). Results A core set comprising specific measures in the domains of lung physiology, lung imaging, survival, dyspnoea, cough and health-related quality of life is proposed as appropriate for consideration for use in a hypothetical 1-year multicentre clinical trial for either CTD-ILD or IPF. As many widely used instruments were found to lack full validation, an agenda for future research is proposed. Conclusion Identification of consensus preliminary domains and instruments to measure them was attained and is a major advance anticipated to facilitate multicentre RCTs in the field.

The impact of rheumatological evaluation in the management of patients with interstitial lung disease

OBJECTIVE We hypothesized that multi-disciplinary assessment of patients with interstitial lung disease (ILD) would lead to improved diagnosis and management. METHODS Our multi-disciplinary ILD group evaluated 50 patients referred to our tertiary care practice over a 12-month period. Evaluation consisted of independent assessments by a pulmonologist and rheumatologist, including complete history and physical examination, review of laboratory data, as well as review of imaging and pathological specimens in conjunction with a radiologist and pathologist experienced in ILD. Therapy was initiated or changed in collaboration with the referring physicians. RESULTS Mean age was 65 years for patients with rheumatic or CTD-related ILD (CTD-ILD) and 70 years for those with idiopathic pulmonary fibrosis (IPF). The final diagnosis after evaluation in the clinic was 25 patients with CTD-ILD, 15 patients with IPF and 10 patients with other forms of lung disease. Of the patients with a final diagnosis of CTD-ILD, 28% were referred with a diagnosis of IPF. Among those referred with CTD-ILD, 36% had their diagnosis changed to an alternate CTD-ILD. In total, the diagnosis was changed in 54% of patients who presented to the ILD clinic. Changes in therapy occurred in 80% of patients with CTD-ILD and in 27% of patients with IPF. CONCLUSION A multi-disciplinary ILD clinic offers patients an innovative mode of health-care delivery that can enhance diagnosis, affect treatment regimens and improve quality of care. Rheumatologists play a significant role in the clinical care of these patients and should evaluate all patients with ILD.

Current status of systemic sclerosis biomarkers: applications for diagnosis, management and drug development

Systemic sclerosis (SSc) is a clinically heterogeneous orphan disease of unknown etiology and no effective therapy. It is characterized by protean manifestations, an unpredictable disease course and variable outcomes. Clinical manifestations reflect underlying autoimmunity, small vessel vasculopathy and progressive multi-organ fibrosis. Predicting disease progression, pattern and severity of complications and response to therapy in SSc remain major challenges both for the management of patients and for the development of effective disease-modifying therapies. This review summarizes contemporary understanding of novel and emerging biomarkers for SSc. We focus on the development of new classification criteria, the utility of SSc-specific autoantibodies as diagnostic and prognostic markers, and on biomarkers for skin and lung involvement. Finally, we review genome-wide expression analysis as a tool to predict therapeutic responses. We anticipate that the development, validation and application of these biomarkers, singly or more likely in combination, will have a transformative impact in SSc, informing early diagnosis, classification and management, as well as the design, execution and interpretation of clinical trials of novel therapeutic agents.

Emerging cellular and molecular targets in fibrosis: implications for scleroderma pathogenesis and targeted therapy.

Purpose of reviewTo summarize the recent advances in understanding the novel cytokine pathways, intracellular signaling molecules, cell-fate decisions, cellular aging and senescence, and the cross-talk of effector cells and the extracellular matrix (ECM) in the pathogenesis of systemic sclerosis (SSc) fibrosis. Recent findingsStudies from the animal models and human beings implicate novel molecular pathways such as Wnts, the chemokines, chemokine (C-X-C motif) ligand 4 and chemokine (C-C motif) ligand 2, and the lipid mediators lysophosphatidic acid and sphingosine-1-phosphate in the pathogenesis of SSc. These signals, coupled with the mesenchymal cell-fate decisions, contribute to aberrant fibroblast activation and myofibroblast accumulation. The resulting deposition and remodeling of ECM alters the biomechanical environment, and leads to further cross-talk of mechanical signals with biochemical mediators such as focal adhesion kinase, integrin signaling, and Yes-associated protein–transcriptional coactivator with PDZ-binding motif signaling pathways. SummaryProgress in understanding the cellular, molecular, and biomechanical regulators of fibrosis has led to the identification of novel targets for interrupting the fibrotic process in SSc. Efforts to antagonize cytokine pathways, affect mesenchymal cell fates, attenuate senescence, and clear activated myofibroblasts, along with modifying the ECM mechanical environment, may ultimately lead to effective therapies in SSc.

Lipids and eicosanoids in fibrosis: emerging targets for therapy.

Purpose of reviewLipid mediators including the lysophospholipids, sphingolipids and eicosanoids have long been implicated in inflammation, cancer and numerous other diseases. Over the last decade, new research suggests a role for these mediators in fibrosis. Recent findingsRecent developments in the study of fibrotic mediators have centered on lysophospholipids and eicosanoids. New research is evaluating metabolic-profiling strategies to quantitatively measure lipid mediators in human plasma. Lysophosphatidic acid receptor antagonists are currently under development with early phase trials scheduled for idiopathic pulmonary fibrosis and scleroderma dermal fibrosis. Eicosanoids have long been implicated in maintaining tissue homeostasis, and the balance of profibrotic and antifibrotic effects has drawn attention in recent years. Targeting the prostanoids, specifically PGE2 and PGI2, as well as the leukotrienes is now being considered for antifibrotic therapies. SummaryLipid mediators have significant roles in many disease processes. Significant research now suggests a critical role for these mediators in the pathogenesis of fibrosis. Targeting these mediators is a promising area of drug discovery.

Interstitial Lung Disease in Scleroderma

Systemic sclerosis is a heterogeneous disease of unknown etiology with limited effective therapies. It is characterized by autoimmunity, vasculopathy, and fibrosis and is clinically manifested by multiorgan involvement. Interstitial lung disease is a common complication of systemic sclerosis and is associated with significant morbidity and mortality. The diagnosis of interstitial lung disease hinges on careful clinical evaluation and pulmonary function tests and high-resolution computed tomography. Effective therapeutic options are still limited. Several experimental therapies are currently in early-phase clinical trials and show promise.

An Autotaxin/Lysophosphatidic Acid/Interleukin-6 Amplification Loop Drives Scleroderma Fibrosis

We previously implicated the lipid mediator lysophosphatidic acid (LPA) as having a role in dermal fibrosis in systemic sclerosis (SSc). The aim of this study was to identify the role of the LPA‐producing enzyme autotaxin (ATX), and to connect the ATX/LPA and interleukin‐6 (IL‐6) pathways in SSc.

Autotaxin activity increases locally following lung injury, but is not required for pulmonary lysophosphatidic acid production or fibrosis

Lysophosphatidic acid (LPA) is an important mediator of pulmonary fibrosis. In blood and multiple tumor types, autotaxin produces LPA from lysophosphatidylcholine (LPC) via lysophospholipase D activity, but alternative enzymatic pathways also exist for LPA production. We examined the role of autotaxin (ATX) in pulmonary LPA production during fibrogenesis in a bleomycin mouse model. We found that bleomycin injury increases the bronchoalveolar lavage (BAL) fluid levels of ATX protein 17‐fold. However, the LPA and LPC species that increase in BAL of bleomycin‐injured mice were discordant, inconsistent with a substrate‐product relationship between LPC and LPA in pulmonary fibrosis. LPA species with longer chain polyunsaturated acyl groups predominated in BAL fluid after bleomycin injury, with 22:5 and 22:6 species accounting for 55 and 16% of the total, whereas the predominant BAL LPC species contained shorter chain, saturated acyl groups, with 16:0 and 18:0 species accounting for 56 and 14% of the total. Further, administration of the potent ATX inhibitor PAT‐048 to bleomycin‐challenged mice markedly decreased ATX activity systemically and in the lung, without effect on pulmonary LPA or fibrosis. Therefore, alternative ATX‐independent pathways are likely responsible for local generation of LPA in the injured lung. These pathways will require identification to therapeutically target LPA production in pulmonary fibrosis.—Black, K. E., Berdyshev, E., Bain, G., Castelino, F. V., Shea, B. S., Probst, C. K., Fontaine, B. A., Bronova, I., Goulet, L., Lagares, D., Ahluwalia, N., Knipe, R. S., Natarajan, V., Tager, A. M. Autotaxin activity increases locally following lung injury, but is not required for pulmonary lysophosphatidic acid production or fibrosis. FASEB J. 30, 2435–2450 (2016). www.fasebj.org