Preclinical study of the long-range safety and anti-inflammatory effects of high-dose oral meglumine.

Meglumine is a methylamino derivative of sorbitol that is an approved drug excipient. Recent preclinical studies suggest that administration of high-dose oral meglumine can exert beneficial medicinal effects to treat diabetes, obesity, and fatty liver disease (NAFLD/nonalcoholic steatohepatitis [NASH]). Here we address gaps in knowledge about the pharmacology and toxicology of this substance administered at high concentrations to explore its medicinal potential. We observed that high-dose meglumine limited secretion of proinflammatory cytokines and cell adhesion molecules from activated human THP-1 or murine RAW264.7 monocytes. Preclinical pharmacokinetic analysis in Swiss mice confirmed that meglumine was orally available. Informed by this data, oral doses of 18 to 75 mM meglumine were administered ad libitum in the drinking water of Sprague-Dawley rats and two cohorts of C57BL/6 mice housed in different vivariums. In a 32-week study, urinary isoprostane levels trended lower in subjects consistent with the possibility of anti-inflammatory effects. In full lifespan studies, there was no detrimental effect on longevity. Heart function evaluated in C57BL/6 mice using an established noninvasive cardiac imaging system showed no detrimental effects on ejection fraction, fractional shortening, left ventricle function or volume, and cardiac output in mice up to 15-month old, with a potential positive trend in heart function noted in elderly mice consistent with earlier reported benefits on muscle stamina. Finally, in a transgenic model of inflammation-associated skin carcinogenesis, the incidence, number, and growth of skin tumors trended lower in subjects receiving meglumine. Overall, the evidence obtained illustrating the long-range safety of high-dose oral meglumine support the rationale for its evaluation as a low-cost modality to limit diabetes, hypertriglyceridemia, and NAFLD/NASH.

NADPH oxidase-mediated induction of reactive oxygen species and extracellular matrix deposition by insulin-like growth factor binding protein-5.

Insulin-like growth factor binding protein-5 (IGFBP-5) induces production of the extracellular matrix (ECM) components collagen and fibronectin both in vitro and in vivo and is overexpressed in patients with fibrosing lung diseases, such as idiopathic pulmonary fibrosis (IPF) and systemic sclerosis (SSc). However, the mechanism by which IGFBP-5 exerts its fibrotic effect is incompletely understood. Recent reports have shown a substantial role of reactive oxygen species (ROS) in fibrosis; thus we hypothesized that IGFBP-5 induces production of ROS to mediate the profibrotic process. In vitro analyses revealed that ROS production was induced by recombinant and adenoviral vector-mediated IGFBP-5 (AdBP5) in a dose- and time-dependent manner, regulated through MEK/ERK and JNK signaling, and primarily mediated by NADPH oxidase (Nox). Silencing IGFBP-5 in SSc and IPF fibroblasts reduced ROS production. The antioxidants diphenyleneiodonium and N-acetylcysteine blocked IGFBP-5-stimulated ECM production in normal, SSc, and IPF human primary lung fibroblasts. In murine fibroblasts lacking critical components of the Nox machinery, AdBP5-stimulated ROS production and fibronectin expression were reduced compared with wild-type fibroblasts. IGFBP-5 stimulated transcriptional expression of Nox3 in human fibroblasts while selective knockdown of Nox3 reduced ROS production by IGFBP-5. Thus IGFBP-5 mediates fibrosis through production of ROS in a Nox-dependent manner.

Transforming growth factor ß1 (TGFß1)-induced CD44V6-NOX4 signaling in pathogenesis of idiopathic pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a progressive clinical syndrome of fatal outcome. The lack of information about the signaling pathways that sustain fibrosis and the myofibroblast phenotype has prevented the development of targeted therapies for IPF. Our previous study showed that isolated fibrogenic lung fibroblasts have high endogenous levels of the hyaluronan receptor, CD44V6 (CD44 variant containing exon 6), which enhances the TGFß1 autocrine signaling and induces fibroblasts to transdifferentiate into myofibroblasts. NADPH oxidase 4 (NOX4) enzyme, which catalyzes the reduction of O2 to hydrogen peroxide (H2O2), has been implicated in the cardiac and lung myofibroblast phenotype. However, whether CD44V6 regulates NOX4 to mediate tissue repair and fibrogenesis is not well-defined. The present study assessed the mechanism of how TGF-ß-1-induced CD44V6 regulates the NOX4/reactive oxygen species (ROS) signaling that mediates the myofibroblast differentiation. Specifically, we found that NOX4/ROS regulates hyaluronan synthesis and the transcription of CD44V6 via an effect upon AP-1 activity. Further, CD44V6 is part of a positive-feedback loop with TGFß1/TGFßRI signaling that acts to increase NOX4/ROS production, which is required for myofibroblast differentiation, myofibroblast differentiation, myofibroblast extracellular matrix production, myofibroblast invasion, and myofibroblast contractility. Both NOX4 and CD44v6 are up-regulated in the lungs of mice subjected to experimental lung injury and in cases of human IPF. Genetic (CD44v6 shRNA) or a small molecule inhibitor (CD44v6 peptide) targeting of CD44v6 abrogates fibrogenesis in murine models of lung injury. These studies support a function for CD44V6 in lung fibrosis and offer proof of concept for therapeutic targeting of CD44V6 in lung fibrosis disorders.

Markers of immune-mediated inflammation in the brains of young adults and adolescents with type 1 diabetes and fatal diabetic ketoacidosis. Is there a difference?

Due to the limited data on diabetic ketoacidosis and brain edema (DKA/BE) in children/adolescents and the lack of recent data on adults with type 1 diabetes (T1D), we addressed the question of whether neuroinflammation was present in the fatal DKA of adults. We performed immunohistochemistry (IHC) studies on the brains of two young adults with T1D and fatal DKA and compared them with two teenagers with poorly controlled diabetes and fatal DKA. C5b-9, the membrane attack complex (MAC) had significantly greater deposits in the grey and white matter of the teenagers than the young adults (p=0.03). CD59, a MAC assembly inhibitory protein was absent, possibly suppressed by the hyperglycemia in the teenagers but was expressed in the young adults despite comparable average levels of hyperglycemia. The receptor for advanced glycation end products (RAGE) had an average expression in the young adults significantly greater than in the teenagers (p=0.02). The autophagy marker Light Chain 3 (LC3) A/B was the predominant form of programmed cell death (PCD) in the teenage brains. The young adults had high expressions of both LC3A/B and TUNEL, an apoptotic cell marker for DNA fragmentation. BE was present in the newly diagnosed young adult with hyperglycemic hyperosmolar DKA and also in the two teenagers. Our data indicate that significant differences in neuroinflammatory components, initiated by the dysregulation of DKA and interrelated metabolic and immunologic milieu, are likely present in the brains of fatal DKA of teenagers when compared with young adults.

Inflammasomes in wound healing and fibrosis.

Inflammasome signalling and downstream cytokine responses mediated by the inflammasome have been found to play an important role, not only in wound healing but also in fibrosis. The inflammasome regulates the secretion of IL-1ß and IL-18 cytokines, and both are critical for the repair of damaged tissue and play a role in fibrosis. However, what dictates the fine balance between normal wound healing versus fibrosis is yet to be fully elucidated. Further investigations into the role of the inflammasomes in these pathologies will be important for the discovery of novel therapeutics that can abrogate fibrosis or promote wound healing in chronic disease.

TANGO1 Dances to Export of Procollagen from the Endoplasmic Reticulum.

The endoplasmic reticulum (ER) to Golgi secretory pathway is an elegantly complex process whereby protein cargoes are manufactured, folded, and distributed from the ER to the cisternal layers of the Golgi stack before they are delivered to their final destinations. The export of large bulky cargoes such as procollagen and its trafficking to the Golgi is a sophisticated mechanism requiring TANGO1 (Transport ANd Golgi Organization protein 1. It is also called MIA3 (Melanoma Inhibitory Activity protein 3). TANGO1 has two prominent isoforms, TANGO1-Long and TANGO1-Short, and each isoform has specific functions. On the luminal side, TANGO1-Long has an HSP47 recruitment domain and uses this protein to collect collagen. It can also tether its paralog isoforms cTAGE5 and TALI and along with these proteins enlarges the vesicle to accommodate procollagen. Recent studies show that TANGO1-Long combines retrograde membrane flow with anterograde cargo transport. This complex mechanism is highly activated in fibrosis and promotes the excessive deposition of collagen in the tissues. The therapeutic targeting of TANGO1 may prove successful in the control of fibrotic disorders. This review focuses on TANGO1 and its complex interaction with other procollagen export factors that modulate increased vesicle size to accommodate the export of procollagen.

Caspase 1 Enhances Transport and Golgi Organization Protein 1 Expression to Promote Procollagen Export From the Endoplasmic Reticulum in Systemic Sclerosis Contributing to Fibrosis.

OBJECTIVE: Transport and Golgi Organization protein 1 (TANGO1) is a protein that regulates the export of procollagen from the endoplasmic reticulum and has a role in the organization of exit sites for general protein export. What regulates the expression of TANGO1 and the role of TANGO1 in fibrosis is poorly understood and has never been studied in the setting of systemic sclerosis (SSc). We undertook this study to determine the role of TANGO1 in SSc fibrosis. METHODS: SSc (n = 15) and healthy (n = 12) primary fibroblast lung cell lines were investigated for the expression of TANGO1. Histologic analyses for TANGO1 were performed on lung biopsy samples (n = 12 SSc patient samples and n = 8 healthy control samples). RESULTS: SSc fibroblasts showed increased expression of TANGO1 protein in cultured fibroblasts. TANGO1 colocalizes with α-smooth muscle actin (α-SMA)-positive cells in SSc lung tissue and is highly up-regulated in the neointima of SSc vessels. TANGO1 expression was dependent on the inflammasome activation of caspase 1. It was also dependent on signaling from the interleukin-1 (IL-1) and transforming growth factor ß (TGFß) receptors. The decrease in TANGO1 down-regulated export of larger cargos including collagen and laminin. Reduced TANGO1 protein had no effect on smaller molecular weight cargoes; however, the secretion of elastin was significantly reduced. CONCLUSION: TANGO1 is markedly increased in SSc fibroblasts and was found to be elevated in lung tissue in association with α-SMA-positive cells. TANGO1 expression is driven by inflammasome-dependent caspase 1 activation and is mediated by IL-1 and TGFß downstream signaling. These observations suggest that during fibrosis, caspase 1 promotes the up-regulation of TANGO1 and the organization of endoplasmic reticulum exits sites, ultimately contributing to procollagen export and fibrosis.

NLRP3 inflammasome is a target for development of broad-spectrum anti-infective drugs.

We describe the molecular mode of action and pharmacodynamics of a new molecular entity (NME) that induces the NLRP3 inflammasome-mediated innate immune response. This innate response reduces the pathogen load in an experimentally induced methicillin-resistant Staphylococcos aureus infection, enhances survival in an experimentally induced Gram-negative bacteremia, and overrides the escape mechanism of an obligate intracellular pathogen, viz. Chlamydia pneumoniae. Furthermore, the NME is more effective than standard-of-care antibiotic therapy in a clinically established multifactorial bacterial infection. Analysis of transcriptional regulation of inflammasome signaling genes and innate/adaptive immune genes revealed consistent and significant host changes responsible for the improved outcomes in these infections. These studies pave the way for the development of first-in-class drugs that enhance inflammasome-mediated pathogen clearance and identify the NLRP3 inflammasome as a drug target to address the global problem of emerging new infectious diseases and the reemergence of old diseases in an antibiotic-resistant form.

The inflammasome activating caspase 1 mediates fibrosis and myofibroblast differentiation in systemic sclerosis.

OBJECTIVE: Systemic sclerosis (SSc) is a chronic idiopathic disease of unknown etiology that is characterized by fibrosis of the skin and visceral organs mediated by activated myofibroblasts. The recently identified inflammasomes are cytosolic receptors that tightly regulate the activity of caspase 1 and downstream signaling molecules such as interleukin-1ß (IL-1ß) and IL-18. The nucleotide-binding oligomerization domain (NOD)-like receptor 3 (NLRP3) inflammasome has been implicated in the development of idiopathic pulmonary fibrosis. This study was undertaken to assess the role of the inflammasome in SSc-related dermal or pulmonary fibrosis. METHODS: Inflammasome gene transcripts were assayed in fibroblasts obtained from patients with SSc. Caspase 1 activation in SSc primary dermal and lung fibroblasts was inhibited, and the levels of hydroxyproline, COL1A1, COL3A1, IL-1ß, IL-18, and α-smooth muscle actin (α-SMA) were measured. The role of the inflammasome in dermal fibrosis was investigated in NLRP3(-/-) and ASC(-/-) mice. RESULTS: We identified increased expression of 40 genes associated with the inflammasome or downstream signaling molecules in SSc fibroblasts. Inhibition of caspase 1 in SSc dermal and lung fibroblasts abrogated the secretion of collagens, IL-1ß, and IL-18. In addition, we observed decreased expression of the myofibroblast protein α-SMA in SSc dermal fibroblasts treated with a caspase 1 inhibitor. Furthermore, NLRP3(-/-) mice and ASC(-/-) mice were resistant to bleomycin-induced skin fibrosis, which suggests a key role for the inflammasome in in vivo fibrosis. CONCLUSION: Innate immune signaling contributes to SSc fibrosis via activation of the inflammasome and caspase 1. These results suggest that inflammasome activation may play an important role in the pathogenesis of SSc.

The Mechanism and Regulation of the NLRP3 Inflammasome during Fibrosis.

Fibrosis is often the end result of chronic inflammation. It is characterized by the excessive deposition of extracellular matrix. This leads to structural alterations in the tissue, causing permanent damage and organ dysfunction. Depending on the organ it effects, fibrosis can be a serious threat to human life. The molecular mechanism of fibrosis is still not fully understood, but the NLRP3 (NOD-, LRR- and pyrin-domain-containing protein 3) inflammasome appears to play a significant role in the pathogenesis of fibrotic disease. The NLRP3 inflammasome has been the most extensively studied inflammatory pathway to date. It is a crucial component of the innate immune system, and its activation mediates the secretion of interleukin (IL)-1ß and IL-18. NLRP3 activation has been strongly linked with fibrosis and drives the differentiation of fibroblasts into myofibroblasts by the chronic upregulation of IL-1ß and IL-18 and subsequent autocrine signaling that maintains an activated inflammasome. Both IL-1ß and IL-18 are profibrotic, however IL-1ß can have antifibrotic capabilities. NLRP3 responds to a plethora of different signals that have a common but unidentified unifying trigger. Even after 20 years of extensive investigation, regulation of the NLRP3 inflammasome is still not completely understood. However, what is known about NLRP3 is that its regulation and activation is complex and not only driven by various activators but controlled by numerous post-translational modifications. More recently, there has been an intensive attempt to discover NLRP3 inhibitors to treat chronic diseases. This review addresses the role of the NLRP3 inflammasome in fibrotic disorders across many different tissues. It discusses the relationships of various NLRP3 activators to fibrosis and covers different therapeutics that have been developed, or are currently in development, that directly target NLRP3 or its downstream products as treatments for fibrotic disorders.

Animal models of scleroderma: fresh insights.

PURPOSE OF REVIEW: Recent years have seen the advent and progress in our understanding of fibrosis and vasculopathy in systemic sclerosis, scleroderma (SSc) largely mediated through the development and study of novel animal models. The most well studied animal models of SSc involve the bleomycin model of induced fibrosis and the Tsk/+ model. However, even though these models provide useful insights into the pathogenesis of fibrosis and vasculopathy, they do not mimic the disease accurately. RECENT FINDINGS: Several mouse models have been developed that have specifically focused on the vasculopathy of SSc and have yielded relevant insights into this disorder further highlighting the novel mechanisms that may be responsible for this pathological feature. Furthermore, the contribution of the innate immune system mediated by the inflammasome in the induction of fibrosis has also demonstrated significant insights, possibly implicating an etiological mechanism of SSc. And recent transgenic or knockout animal models have emphasized the relevance of macrophage chemoattractant protein-1 (MCP-1), alpha-melanocyte stimulating hormone (α-MSH), and peroxisome proliferator-activated receptor-gamma (PPARγ) in fibrosis. SUMMARY: Recent advances in animal models of SSc have elucidated the involvement of relevant proteins that appear to mediate vasculopathy and also implicated the involvement of the innate immune system in fibrosis. These models have identified novel therapeutic targets that may lead to more effective treatments for this incurable disease.

Soluble Receptor for Glycation End-products Concentration Increases Following the Treatment of Severe Diabetic Ketoacidosis

Objective: To determine the time relationships of soluble receptor for glycation end-products (sRAGE), [a decoy of the advanced glycation end-products (AGE)-RAGE axis] and D-lactate, (a metabolite of methylglyoxal) in the inflammatory response to diabetic ketoacidosis (DKA). Methods: Sixteen children and adolescents with type 1 diabetes (T1D) had blood samples obtained, 6-12 hours into treatment, at three weeks and three months post start of treatment. sRAGE and D-lactate concentrations at three months were considered baseline. Expression of RAGE was investigated in the myocardium of a newly diagnosed and untreated young person with fatal T1D/DKA. Results: sRAGE 6-12 hours after the start of treatment was 39% lower than the values at two weeks (p=0.0036) and at three months (p=0.0023) post treatment. D-lactate was higher during treatment than at three weeks (p=0.04) and at three months (p=0.035). Conclusion: sRAGE concentration was decreased during treatment, compared to concentrations at two weeks and three months after treatment. The increased D-lactate during treatment was in keeping with the known increase in dicarbonyls at this time. The finding of RAGE expression in a young myocardium prior to DKA treatment suggested cardiovascular inflammation pre-treatment and at a young age.

3-Deoxyglucosone-collagen alters human dermal fibroblast migration and adhesion: implications for impaired wound healing in patients with diabetes.

The interaction of fibroblasts with the extracellular matrix is critical for wound healing. Advanced glycation end products (AGEs) occur through nonenzymatic glycation of long-lived proteins such as collagens. One precursor to these modifications, 3-deoxyglucosone (3DG), is elevated in patients with diabetes and contributes to the accumulation of AGEs on collagen with increasing chronological age. Because wound repair is dependent on fibroblast migration, proliferation, and expression of extracellular matrix proteins, we examined the role of 3DG-treated collagen and the subsequent response of fibroblasts to this modification. We found that fibroblasts adhere more strongly to 3DG-treated collagen and do not migrate efficiently into the wound site. We further show that 3DG-treated collagen induces perinuclear localization of focal adhesion kinase and paxillin, indicative of decreased association of these proteins with the cytoskeleton. Additionally, these cells expressed higher levels of the misfolded indicator protein growth arrest and DNA damage inducible gene 153. These data suggest that fibroblast/matrix interactions are altered as AGEs accumulate and affect focal adhesion formation. Furthermore, 3DG may be a factor mediating chronic wounds observed in patients with diabetes and in the elderly by altering the signaling within the fibroblast and inducing the misfolding of proteins.

1-Peptidyl-2-arachidonoyl-3-stearoyl-sn-glyceride: an immunologically active lipopeptide from goat serum (Capra hircus) is an endogenous damage-associated molecular pattern.

Experiments were undertaken to isolate a component of the serum of goat (Capra hircus) that is effective at mediating an innate immune response. This report describes the isolation and structure elucidation of 1-(N-acetyl-ALYDKGYTSKEQKDCVGI)-2-arachidonoyl-3-stearoyl glyceride (1) and its immunomodulatory activity. A dose-response relationship for inflammatory cytokine and chemokine production and release from human fibroblasts incubated with nanomolar concentrations of 1 was shown. Moreover, the membrane transport role of the diacylglycerol moiety in 1 is demonstrated with nanomolar quantities of the transfected N-acetyl peptide moiety of 1 also inducing inflammatory cytokine and chemokine production and release. The apparent EC99 for 1 was 3 ng/mL (1 nM). The likely biological role for naturally occurring 1 as a damage-associated molecular pattern is postulated.

The MicroRNA miR-155 Is Essential in Fibrosis.

The function of microRNAs (miRNAs) during fibrosis and the downstream regulation of gene expression by these miRNAs have become of great biological interest. miR-155 is consistently upregulated in fibrotic disorders, and its ablation downregulates collagen synthesis. Studies demonstrate the integral role of miR-155 in fibrosis, as it mediates TGF-ß1 signaling to drive collagen synthesis. In this review, we summarize recent findings on the association between miR-155 and fibrotic disorders. We discuss the cross-signaling between macrophages and fibroblasts that orchestrates the upregulation of collagen synthesis mediated by miR-155. As miR-155 is involved in the activation of the innate and adaptive immune systems, specific targeting of miR-155 in pathologic cells that make excessive collagen could be a viable option before the depletion of miR-155 becomes an attractive antifibrotic approach.

The IL-1 family of cytokines. Do they have a role in scleroderma fibrosis?

Systemic sclerosis is a profibrotic autoimmune disease mediated by the dysregulation in collagen synthesis, leading to the increased deposition of collagens, primarily type I and III, and the deposition of other extracellular matrix proteins in the skin and internal organs, in a mechanism that is thought to be an over active wound healing process. These patients experience significant morbidity and the mortality rate in this disease is high. Indeed, scleroderma is the most deadly of diseases in the autoimmune spectrum. Recent evidence has placed the assembly and chronic activation of the inflammasome as a central driver of fibrosis. Once assembled, the inflammasome is a large protein complex that regulates the release of IL-1, IL-18, and IL-33, which are thought to play a role in the fibrotic response. IL-36 also belongs to the IL-1 family of cytokines and is a new comer to this field of research. Recent analyses of the IL-1 family of cytokines have demonstrated that many of them play a role in skin inflammation and fibrosis and their corresponding antagonists (IL-1RA and IL-36RA) can abrogate this pathology. Understanding how these cytokines are regulated and how they contribute to fibrosis will be important to understanding this pathology and may shed light in new areas for therapeutic development.

Mir-155 is overexpressed in systemic sclerosis fibroblasts and is required for NLRP3 inflammasome-mediated collagen synthesis during fibrosis.

BACKGROUND: Despite the important role that microRNAs (miRNAs) play in immunity and inflammation, their involvement in systemic sclerosis (SSc) remains poorly characterized. miRNA-155 (miR-155) plays a role in pulmonary fibrosis and its expression can be induced with interleukin (IL)-1ß. SSc fibroblasts have activated inflammasomes that are integrally involved in mediating the myofibroblast phenotype. In light of this, we investigated whether miR-155 played a role in SSc and if its expression was dependent on inflammasome activation. METHODS: miR-155 expression was confirmed in SSc dermal and lung fibroblasts by quantitative polymerase chain reaction (PCR). Wild-type and NLRP3-deficient murine fibroblasts were utilized to explore the regulation of miR-155 during inflammasome activation. miR-155-deficient fibroblasts and retroviral transductions with a miR-155 expression or control vectors were used to understand the contribution of miR-155 in fibrosis. RESULTS: miR-155 was significantly increased and the highest expressing miRNA in SSc lung fibroblasts. Its expression was dependent on inflammasome activation as miR-155 expression could be blocked when inflammasome signaling was inhibited. In the absence of miR-155, inflammasome-mediated collagen synthesis could not be induced but was restored when miR-155 was expressed in miR-155-deficient fibroblasts. CONCLUSIONS: miR-155 is upregulated in SSc. These results suggest that the inflammasome promotes the expression of miR-155 and that miR-155 is a critical miRNA that drives fibrosis.

Description of 12 cases of nephrogenic fibrosing dermopathy and review of the literature.

OBJECTIVES: To review the clinical and laboratory features of 12 cases of nephrogenic fibrosing dermopathy (NFD) studied at our institution and of 70 previously described cases in the literature. METHODS: Clinical evaluation and laboratory studies of 12 patients with NFD associated with chronic hemodialysis or peritoneal dialysis for end-stage renal disease and a review of 23 previous publications describing 70 patients with this disease. RESULTS: Eleven patients undergoing chronic hemodialysis and 1 patient undergoing chronic peritoneal dialysis for end-stage renal failure developed a severe and progressive cutaneous fibrotic process with woody induration of legs, thighs, hands, and forearms, and severe loss of motion and flexion contractures in multiple joints. Several patients displayed systemic involvement including fibrosis of muscles, myocardium, and lungs and marked elevations of the erythrocyte sedimentation rate and/or C-reactive protein. Three patients died within 2 years of symptom onset. A review of previously published reports of this disorder confirmed the presence of systemic involvement and a poor prognosis with a high mortality rate. CONCLUSIONS: NFD is a severe and usually progressive systemic fibrotic disease affecting the dermis, subcutaneous fascia, and striated muscles. It also appears that the disease can cause fibrosis of lungs, myocardium, and other organs.

Morbidity and mortality of patients diagnosed with systemic sclerosis after the age of 75: a nested case-control study.

This study aims to characterize the clinical features of a cohort of patients diagnosed with systemic sclerosis (SSc) after the age of 75 and compare them to a group diagnosed at a younger age. We record the review of 769 patients diagnosed with SSc over the past 16 years. Utilizing a nested case-control model, we compare demographics, disease severity, morbidity, and mortality data of all patients diagnosed after the age of 75 to sex- and disease-type-matched, randomly selected group of patients diagnosed with SSc before the age of 60. Twelve patients were diagnosed with SSc after the age of 75, seven with the diffuse, and five with the limited form. It took longer to diagnose SSc in the older patients, and comparison of disease severity revealed a worse pulmonary picture and a more frequent development of malignancy in the older patients as compared with the younger ones. During a mean follow-up of 36.2 months, our cohort of patients did not have worsening in their disease severity, though 6 months after the last follow-up, six patients died. We conclude that a diagnosis of SSc at an older age appears to be a poor prognostic indicator related to both disease severity and comorbidities. A higher clinical suspicion will lead to an earlier diagnosis and a potential decrease in morbidity and mortality.

Identification of Optimal Mouse Models of Systemic Sclerosis by Interspecies Comparative Genomics.

OBJECTIVE: Understanding the pathogenesis of systemic sclerosis (SSc) is confounded by considerable disease heterogeneity. Animal models of SSc that recapitulate distinct subsets of disease at the molecular level have not been delineated. We applied interspecies comparative analysis of genomic data from multiple mouse models of SSc and patients with SSc to determine which animal models best reflect the SSc intrinsic molecular subsets. METHODS: Gene expression measured in skin from mice with sclerodermatous graft-versus-host disease (GVHD), bleomycin-induced fibrosis, Tsk1/+ or Tsk2/+ mice was mapped to human orthologs and compared to SSc skin biopsy-derived gene expression. Transforming growth factor ß (TGFß) activation was assessed using a responsive signature in mice, and tumor necrosis factor receptor superfamily member 12A (TNFRSF12A) expression was measured in SSc patient and mouse skin. RESULTS: Gene expression in skin from mice with sclerodermatous GVHD and bleomycin-induced fibrosis corresponded to that in SSc patients in the inflammatory molecular subset. In contrast, Tsk2/+ mice showed gene expression corresponding to the fibroproliferative SSc subset. Enrichment of a TGFß-responsive signature was observed in both Tsk2/+ mice and mice with bleomycin-induced skin fibrosis. Expression of TNFRSF12A (the TWEAK receptor/fibroblast growth factor-inducible 14) was elevated in skin from patients with fibroproliferative SSc and the skin of Tsk2/+ mice. CONCLUSION: This study reveals similarities in cutaneous gene expression between distinct mouse models of SSc and specific molecular subsets of the disease. Different pathways underlie the intrinsic subsets including TGFß, interleukin-13 (IL-13), and IL-4. We identify a novel target, Tnfrsf12a, with elevated expression in skin from patients with fibroproliferative SSc and Tsk2/+ mice. These findings will inform mechanistic and translational preclinical studies in SSc.