Angiotensinogen gene G-6A polymorphism influences idiopathic pulmonary fibrosis disease progression

Catch your breath: The protective role of the angiotensin AT2 receptor for the treatment of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive interstitial lung disease whereby excessive deposition of extracellular matrix proteins (ECM) ultimately leads to respiratory failure. While there have been advances in pharmacotherapies for pulmonary fibrosis, IPF remains an incurable and irreversible disease. There remains an unmet clinical need for treatments that reverse fibrosis, or at the very least have a more tolerable side effect profile than currently available treatments. Transforming growth factor β1(TGFβ1) is considered the main driver of fibrosis in IPF. However, as our understanding of the role of the pulmonary renin-angiotensin system (PRAS) in the pathogenesis of IPF increases, it is becoming clear that targeting angiotensin receptors represents a potential novel treatment strategy for IPF - in particular, via activation of the anti-fibrotic angiotensin type 2 receptor (AT2R). This review describes the current understanding of the pathophysiology of IPF and the mediators implicated in its pathogenesis; focusing on TGFβ1, angiotensin II and related peptides in the PRAS and their contribution to fibrotic processes in the lung. Preclinical and clinical assessment of currently available AT2R agonists and the development of novel, highly selective ligands for this receptor will also be described, with a focus on compound 21, currently in clinical trials for IPF. Collectively, this review provides evidence of the potential of AT2R as a novel therapeutic target for IPF.

Genetic Polymorphism in Angiotensinogen and Its Association with Cardiometabolic Diseases

Angiotensinogen (AGT) is one of the most significant enzymes of the renin-angiotensin-aldosterone system (RAAS) which is involved in the regulation and maintenance of blood pressure. AGT is involved in the production of angiotensin I which is then converted into angiotensin II that leads to renal homeostasis. However, various genetic polymorphisms in AGT have been discovered in recent times which have shown an association with various diseases. Genetic polymorphism increases the level of circulating AGT in blood which exaggerates the effects produced by AGT. The associated diseases occur due to various effects produced by increased AGT levels. Several cardiovascular diseases including myocardial infarction, coronary heart disease, heart failure, hypertrophy, etc. are associated with AGT polymorphism. Other diseases such as depression, obesity, diabetic nephropathy, pre-eclampsia, and liver injury are also associated with some variants of AGT gene. The most common variants of AGT polymorphism are M235T and T174M. The two variants are associated with many diseases. Some other variants such as G-217A, A-6G, A-20C and G-152A, are also present but they are not as significant as that of M235T and T174M variants. These variants increase the level of circulating AGT and are associated with prevalence of different diseases. These diseases occur through various pathological pathways, but the initial reason remains the same, i.e., increased level of AGT in the blood. In this article, we have majorly focused on how genetic polymorphism of different variants of AGT gene is associated with the prevalence of different diseases.

The Effectiveness of Nintedanib in Patients with Idiopathic Pulmonary Fibrosis, Familial Pulmonary Fibrosis and Progressive Fibrosing Interstitial Lung Diseases: A Real-World Study

Background: Nintedanib is an oral multitarget tyrosine kinase inhibitor approved for the treatment of patients with idiopathic pulmonary fibrosis (IPF). Recent evidence demonstrated that nintedanib reduced functional disease progression also in subjects with non-IPF progressive fibrosing interstitial lung disease (PF-ILD). However, real-life data on the effectiveness of nintedanib in PF-ILD and familial pulmonary fibrosis (FPF) are lacking. Methods: this retrospective monocentric study enrolled 197 patients affected with IPF, PF-ILD and FPF treated with nintedanib at the Referral Centre of Siena from 2014 to 2021. Pulmonary functional tests and survival data were collected throughout the observation period for the evaluation of mortality and disease progression outcomes. Results: nintedanib treatment significantly reduced the FVC decline rate in IPF and PF-ILD subgroups, but not in FPF subjects. No significant differences were observed among the subgroups in terms of survival, which appeared to be influenced by gender and impaired lung function (FVC < 70% of predicted value). Concerning disease progression rate, a diagnosis of FPF is associated with more pronounced FVC decline despite nintedanib treatment. Conclusions: our research studies the effectiveness and safety of nintedanib in reducing functional disease progression of IPF and PF-ILD. FPF appeared to be less responsive to nintedanib, even though no differences were observed in terms of survival.

Proteomic analysis of serum samples of paracoccidioidomycosis patients with severe pulmonary sequel

Background

Pulmonary sequelae (PS) in patients with chronic paracoccidioidomycosis (PCM) typically include pulmonary fibrosis and emphysema. Knowledge of the molecular pathways involved in PS of PCM is required for treatment and biomarker identification.

Methodology/Principal findings

This non-concurrent cohort study included 29 patients with pulmonary PCM that were followed before and after treatment. From this group, 17 patients evolved to mild/ moderate PS and 12 evolved severe PS. Sera from patients were evaluated before treatment and at clinical cure, serological cure, and apparent cure. A nanoACQUITY UPLC-Xevo QT MS system and PLGS software were used to identify serum differentially expressed proteins, data are available via ProteomeXchange with identifier PXD026906. Serum differentially expressed proteins were then categorized using Cytoscape software and the Reactome pathway database. Seventy-two differentially expressed serum proteins were identified in patients with severe PS compared with patients with mild/moderate PS. Most proteins altered in severe PS were involved in wound healing, inflammatory response, and oxygen transport pathways. Before treatment and at clinical cure, signaling proteins participating in wound healing, complement cascade, cholesterol transport and retinoid metabolism pathways were downregulated in patients with severe PS, whereas signaling proteins in gluconeogenesis and gas exchange pathways were upregulated. At serological cure, the pattern of protein expression reversed. At apparent cure pathways related with tissue repair (fibrosis) became downregulated, and pathway related oxygen transport became upregulated. Additionally, we identified 15 proteins as candidate biomarkers for severe PS.

Conclusions/Significance

Development of severe PS is related to increased expression of proteins involved in glycolytic pathway and oxygen exchange), indicative of the greater cellular activity and replication associated with early dysregulation of wound healing and aberrant tissue repair. Our findings provide new targets to study mechanisms of PS in PCM, as well as potential biomarkers.

Pulmonary fibrosis is the main sequel of paracoccidioidomycosis (PCM), a fungal disease that affects mainly men, rural workers. The development of pulmonary fibrosis is complex and involves several mechanisms that culminate in aberrant collagen production and deposition in the lungs making it became stiff and blocking the air passages. These changes lead to difficulty in breathing and in PCM patients dyspnea in response to high or low levels of exertion is common. Therefore, these patients show incapacity to work and the decreased quality of life. With the possibility of identifying some marker, for example, it could help the indication of respiratory physiotherapy, professional rehabilitation, or therapeutic intervention. This is the first study to examine the pulmonary sequelae (PS) in patients with paracoccidioidomycosis using an approach combining proteomics with bioinformatics. Here, we identify the specific proteome pattern found in PCM patients with severe sequelae that distinguishes these patients from that with mild/moderate sequelae. Our results showed that time points immediately before treatment and at clinical cure are key moments at which PS can progress to severe PS due a dysregulation in wound healing with consequent delayed in the healing processes resulting in an aberrant scar. As such, we suggest that the prognoses for severe PS should be considered as soon as possible and as early as diagnosis of PCM. Furthermore, we used proteomics to identify possible serum biomarkers with which to predict the likely development of severe PS, to be validated in future studies.

Germline Genetic Variants of the Renin-Angiotensin System, Hypoxia and Angiogenesis in Non-Small Cell Lung Cancer Progression: Discovery and Validation Studies

Simple Summary

The presence of polymorphic gene variants in the human genome provides extensive genetic (and eventually phenotypic) variation affecting both normal physiological mechanisms and cancer pathogenesis. Functional genetic polymorphisms might have predictive and/or prognostic value in lung cancer, opening novel opportunities to improve prediction and guide clinical reasoning and therapeutics in lung cancer patients. Recent knowledge pinpoints a pleiotropic role for renin-angiotensin system, particularly in the lung and mainly through locally regulated alternative molecules and secondary pathways. Dysregulation of this system play a role in cell proliferation, hypoxia and angiogenesis, which processes are involved in lung cancer progression. Here we suggest that polymorphic variants in genes coding for renin-angiotensin system might play a role in Non-Small Cell Lung Cancer progression.

Abstract

Introduction: The renin–angiotensin system (RAS) is involved in cell proliferation, immunoinflammatory response, hypoxia and angiogenesis, which are critical biological processes in lung cancer. Our aim was to study the association of putatively functional genetic polymorphisms in genes coding for proteins involved in RAS, hypoxia and angiogenesis with non-small cell lung cancer (NSCLC) prognosis. Methods: Genotyping of 52 germline variants from genes of the RAS and hypoxic/angiogenic factors/receptors was performed using MassARRAY iPLEX Gold in a retrospective cohort (n = 167) of advanced NSCLC patients. Validation of the resulting genetic markers was conducted in an independent group (n = 190), matched by clinicopathological characteristics. Results: Multivariate analysis on the discovery set revealed that MME rs701109 C carriers were protected from disease progression in comparison with homozygous T (hazard ratio (HR) = 0.5, 95% confidence interval (CI) = 0.2–0.8, p = 0.010). Homozygous A and T genotypes for KDR rs1870377 were at increased risk for disease progression and death compared to heterozygous (HR = 1.7, 95% CI = 1.2–2.5, p = 0.005 and HR = 2.1, 95% CI = 1.2–3.4, p = 0.006, respectively). Carriers of homozygous genotypes for ACE2 rs908004 presented increased risk for disease progression, only in the subgroup of patients without tumour actionable driver mutations (HR = 2.9, 95% CI = 1.3–6.3, p = 0.010). Importantly, the association of homozygous genotypes in MME rs701109 with risk for disease progression was confirmed after multivariate analysis in the validation set. Conclusion: This study provides evidence that MME polymorphism, which encodes neprilysin, may modulate progression-free survival in advanced NSCLC. Present genetic variation findings will foster basic, translational, and clinical research on their role in NSCLC.

Renin-Angiotensin System in Lung Tumor and Microenvironment Interactions

The mechanistic involvement of the renin-angiotensin system (RAS) reaches beyond cardiovascular physiopathology. Recent knowledge pinpoints a pleiotropic role for this system, particularly in the lung, and mainly through locally regulated alternative molecules and secondary pathways. Angiotensin peptides play a role in cell proliferation, immunoinflammatory response, hypoxia and angiogenesis, which are critical biological processes in lung cancer. This manuscript reviews the literature supporting a role for the renin-angiotensin system in the lung tumor microenvironment and discusses whether blockade of this pathway in clinical settings may serve as an adjuvant therapy in lung cancer.

Association of Angiotensin Modulators With the Course of Idiopathic Pulmonary Fibrosis

BACKGROUND

Angiotensin peptides have been implicated in idiopathic pulmonary fibrosis (IPF) pathogenesis. Angiotensin modulators are used to treat arterial hypertension, a frequent comorbidity of IPF. This post hoc analysis evaluated associations of antihypertensive treatments with disease-related outcomes in IPF.

METHODS

All patients randomized to placebo (n = 624) in the CAPACITY and ASCEND studies were categorized by antihypertensive treatment at baseline. Outcomes of disease progression (first occurrence of ≥ 10% absolute decline in % predicted FVC, ≥ 50-m decline in 6-min walk distance, or death) and all-cause mortality were assessed over 52 weeks.

RESULTS

At baseline, 111 and 121 patients were receiving an angiotensin-converting enzyme inhibitor (ACEi) or an angiotensin II receptor blocker (ARB), respectively; 392 were receiving neither. In multivariable analyses adjusted for differences in baseline characteristics compared with the non-ACEi/ARB group, ACEi treatment (hazard ratio [HR], 0.6 [95% CI, 0.4-0.9]; P = .026), but not ARB (HR, 0.9 [95% CI, 0.6-1.2]; P = .413), was associated with slower disease progression. Furthermore, the increase in all-cause mortality associated with cardiovascular disease was not observed in the ACEi group (HR, 1.1 [95% CI, 0.5-2.9]; P = .782), which presented a similar percentage of IPF-related mortality as the non-ACEi/ARB group (3.6% vs 3.6%). In contrast, patients in the ARB group had greater risk of all-cause mortality (HR, 2.5 [95% CI, 1.2-5.2]). These observations were validated in a pooled analysis that included patients from the INSPIRE trial.

CONCLUSIONS

Prospective clinical trials are needed to evaluate whether angiotensin modulators may be beneficial to clinical outcomes in IPF.

TRIAL REGISTRY

ClinicalTrials.gov; Nos.: NCT01366209, NCT00287716, NCT00287729, NCT00075998; URL: www.clinicaltrials.gov).

Towards a global initiative for fibrosis treatment (GIFT)

Idiopathic pulmonary fibrosis (IPF) is a progressive lung disease characterised by increased scarring of lung tissue. Despite the recent introduction of novel drugs that slow disease progression, IPF remains a deadly disease, and the benefits of these new drugs differ markedly between patients.

Human diseases arise due to alterations in an almost limitless network of interconnected genes, proteins, metabolites, cells and tissues, in direct relationship with a continuously changing macro- or microenvironment. Systems biology is a novel research strategy that seeks to understand the structure and behaviour of the so-called “emergent properties” of complex systems, such as those involved in disease pathogenesis, which are most often overlooked when just one element of disease pathogenesis is observed in isolation.

This article summarises the debate that took place during a European Respiratory Society research seminar in Barcelona, Spain on December 15–16, 2016, which focused on how systems biology could generate new data by integrating the different IPF pathogenic levels of complexity. The main conclusion of the seminar was to create a global initiative to improve IPF outcomes by integrating cutting-edge international research that leverages systems biology to develop a precision medicine approach to tackle this devastating disease.

A novel call to action for implementing systems biology in IPF researchhttp://ow.ly/Is0A30gpnVb

Discovery and validation of extracellular/circulating microRNAs during idiopathic pulmonary fibrosis disease progression

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a chronic fibrosing interstitial lung disease of unknown etiology that is currently untreatable. In this study we aim to characterize the potential of extracellular/circulating microRNAs (miRNAs) in serum as biomarkers for IPF.

METHODS

Total serum RNAs were isolated from serum from healthy control subjects (n=12), rapid progressive (n=12) and slowly progressive IPF patients (n=12). Serum RNA was analyzed by using TaqMan microRNA assays containing probes for 366 human miRNAs, and selected findings were validated with quantitative RT-PCR. Target prediction and pathway analysis on the significant differential miRNAs were performed using DIANA-mirPath.

RESULTS

We found 47 significantly differentially expressed serum miRNAs (p<0.05) in rapid progressive or slowly progressive IPF patients compared to healthy controls, including 21 up-regulated miRNAs and 26 down-regulated miRNAs. Bioinformatic analysis by DIANA-mirPath demonstrated that 53 KEGG biological processes were significantly enriched (p < 0.05, FDR corrected) among differentially expressed serum miRNAs, including TGF-beta signaling pathway (p < 0.0001), MAPK signaling pathway (p < 0.0001), PI3K-Akt signaling pathway (p < 0.0001), Wnt signaling pathway (p < 0.0001), HIF-1 signaling pathway (p < 0.0001), Regulation of actin cytoskeleton (p < 0.0001), Jak-STAT signaling pathway (p < 0.0001), Notch signaling pathway (p < 0.0001), and Cytokine-cytokine receptor interaction (p = 0.0062). We further validated six miRNAs (miR-21, miR-199a-5p, miR-200c, miR-31, let-7a, and let-7d) for further validation using an independent cohort of 20 rapid progressive IPF, 24 slowly progressive IPF patients and 20 healthy controls. In agreement with the preliminary data from miRNA assay, miR-21, miR-199a-5p, and miR-200c were significantly increased in serums of IPF patients while miR-31, let-7a, and let-7d were significantly under expressed in serums of IPF patients compared to healthy controls.

CONCLUSIONS

These studies demonstrated that extracellular/circulating miRNAs in serum could be potentially served as novel regulators influencing disease progression of IPF.

The pathogenesis of bleomycin-induced lung injury in animals and its applicability to human idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a devastating disease of unknown etiology, for which there is no curative pharmacological therapy. Bleomycin, an anti-neoplastic agent that causes lung fibrosis in human patients has been used extensively in rodent models to mimic IPF. In this review, we compare the pathogenesis and histological features of human IPF and bleomycin-induced pulmonary fibrosis (BPF) induced in rodents by intratracheal delivery. We discuss the current understanding of IPF and BPF disease development, from the contribution of alveolar epithelial cells and inflammation to the role of fibroblasts and cytokines, and draw conclusions about what we have learned from the intratracheal bleomycin model of lung fibrosis.

Revealing the pathogenic and aging-related mechanisms of the enigmatic idiopathic pulmonary fibrosis. an integral model

A growing body of evidence indicates that aberrant activation of alveolar epithelial cells and fibroblasts in an aging lung plays a critical role in the pathogenesis of idiopathic pulmonary fibrosis (IPF). However, the biopathological processes linking aging with IPF and the mechanisms responsible for the abnormal activation of epithelial cells and fibroblasts have not been elucidated. Many of the hallmarks of aging (e.g., genomic instability, telomere attrition, epigenetic alterations, mitochondrial dysfunction, and cellular senescence) have been proposed as essential mechanisms for the development of IPF; however, these disturbances are not restricted to IPF and also occur in other aging-related lung disorders, primarily chronic obstructive pulmonary disease (COPD). Therefore, an unanswered question is why a current/former smoker of about 60 years of age with shorter telomeres, alveolar epithelial senescence, excessive oxidative stress, and mitochondrial dysfunction develops IPF and not COPD; in other words, what makes old lungs specifically susceptible to develop IPF? In this Perspective, we propose an integral model in which the combination of some gene variants and/or gene expression in the aging lung results in the loss of epithelial integrity and consequently in the failure of the alveoli to correctly respond to injury and to face the stress associated with mechanical stretch. Afterward, a distinctive epigenetic "reprogramming" that affects both epithelial cells and fibroblasts provokes, among others, the recapitulation of developmental pathways and the aberrant activation and miscommunication between both cell types, resulting in the exaggerated production and accumulation of extracellular matrix and the subsequent destruction of the lung architecture.

The Toll-like receptor 3 L412F polymorphism and disease progression in idiopathic pulmonary fibrosis

RATIONALE

Idiopathic pulmonary fibrosis (IPF) is a fatal progressive interstitial pneumonia. The innate immune system provides a crucial function in the recognition of tissue injury and infection. Toll-like receptor 3 (TLR3) is an innate immune system receptor. We investigated the role of a functional TLR3 single-nucleotide polymorphism in IPF.

OBJECTIVES

To characterize the effects of the TLR3 Leu412Phe polymorphism in primary pulmonary fibroblasts from patients with IPF and disease progression in two independent IPF patient cohorts. To investigate the role of TLR3 in a murine model of pulmonary fibrosis.

METHODS

TLR3-mediated cytokine, type 1 IFN, and fibroproliferative responses were examined in TLR3 wild-type (Leu/Leu), heterozygote (Leu/Phe), and homozygote (Phe/Phe) primary IPF pulmonary fibroblasts by ELISA, real-time polymerase chain reaction, and proliferation assays. A murine model of bleomycin-induced pulmonary fibrosis was used in TLR3 wild-type (tlr3(+/+)) and TLR3 knockout mice (tlr3(-/-)). A genotyping approach was used to investigate the role of the TLR3 L412F polymorphism in disease progression in IPF using survival analysis and longitudinal decline in FVC.

MEASUREMENTS AND MAIN RESULTS

Activation of TLR3 in primary lung fibroblasts from TLR3 L412F-variant patients with IPF resulted in defective cytokine, type I IFN, and fibroproliferative responses. We demonstrate increased collagen and profibrotic cytokines in TLR3 knockout mice (tlr3(-/-)) compared with wild-type mice (tlr3(+/+)). TLR3 L412F was also associated with a significantly greater risk of mortality and an accelerated decline in FVC in patients with IPF.

CONCLUSIONS

This study reveals the crucial role of defective TLR3 function in promoting progressive IPF.

Tanshinone IIA attenuates bleomycin-induced pulmonary fibrosis via modulating angiotensin-converting enzyme 2/ angiotensin-(1-7) axis in rats

Pulmonary fibrosis (PF) is a common complication in those interstitial lung diseases patients, which will result in poor prognosis and short survival. Traditional therapeutic methods such as glucocorticoid and cytotoxic drugs are insufficient for treating PF and may cause severe side effects. Recent studies showed that traditional Chinese herbal abstraction such as Tanshinone IIA (TIIA) was displayed significant anti-PF effects in animal models. However, the exact mechanisms underlying the protective effects of TIIA were not fully understood. Here we further investigated the protective effects of TIIA and its mechanisms underlying. PF models of rat were induced by bleomycin (BLM); TIIA was administered subsequently. The PF changes were identified by histopathological analyses. The results showed that BLM resulted in severe PF and alveolar inflammation; together with significant elevation of transforming growth factor-β 1 (TGF-β1). Angiotensin-converting enzyme 2 (ACE-2) together with angiotensin-(1-7) [ANG-(1-7)] were both greatly reduced after BLM administration. TIIA treatment notably attenuated BLM induced PF and inflammation, decreased expression of TGF-β1 and reversed ACE-2 and ANG-(1-7) production in rat lungs. Thus we may draw the conclusion that TIIA may exert protective effects on BLM induced PF in rats, and the ACE-2/ANG-(1-7) axis may ascribe to those protective effects.

Genetic architecture of human fibrotic diseases: disease risk and disease progression

Genetic studies of human diseases have identified multiple genetic risk loci for various fibrotic diseases. This has provided insights into the myriad of biological pathways potentially involved in disease pathogenesis. These discoveries suggest that alterations in immune responses, barrier function, metabolism and telomerase activity may be implicated in the genetic risks for fibrotic diseases. In addition to genetic disease-risks, the identification of genetic disease-modifiers associated with disease complications, severity or prognosis provides crucial insights into the biological processes implicated in disease progression. Understanding the biological processes driving disease progression may be critical to delineate more effective strategies for therapeutic interventions. This review provides an overview of current knowledge and gaps regarding genetic disease-risks and genetic disease-modifiers in human fibrotic diseases.

Fibrosis of two: Epithelial cell-fibroblast interactions in pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is characterized by the progressive and ultimately fatal accumulation of fibroblasts and extracellular matrix in the lung that distorts its architecture and compromises its function. IPF is now thought to result from wound-healing processes that, although initiated to protect the host from injurious environmental stimuli, lead to pathological fibrosis due to these processes becoming aberrant or over-exuberant. Although the environmental stimuli that trigger IPF remain to be identified, recent evidence suggests that they initially injure the alveolar epithelium. Repetitive cycles of epithelial injury and resultant alveolar epithelial cell death provoke the migration, proliferation, activation and myofibroblast differentiation of fibroblasts, causing the accumulation of these cells and the extracellular matrix that they synthesize. In turn, these activated fibroblasts induce further alveolar epithelial cell injury and death, thereby creating a vicious cycle of pro-fibrotic epithelial cell-fibroblast interactions. Though other cell types certainly make important contributions, we focus here on the "pas de deux" (steps of two), or perhaps more appropriate to IPF pathogenesis, the "folie à deux" (madness of two) of epithelial cells and fibroblasts that drives the progression of pulmonary fibrosis. We describe the signaling molecules that mediate the interactions of these cell types in their "fibrosis of two", including transforming growth factor-β, connective tissue growth factor, sonic hedgehog, prostaglandin E2, angiotensin II and reactive oxygen species. This article is part of a Special Issue entitled: Fibrosis: Translation of basic research to human disease.

Angiotensinogen promoter polymorphisms predict low diffusing capacity in U.S. and Spanish IPF cohorts

BACKGROUND

Single nucleotide polymorphisms (SNPs) in angiotensinogen (AGT) at positions -20 and -6 are associated with increased severity and progression of various fibrotic diseases. Our earlier work demonstrated that the progression of idiopathic pulmonary fibrosis (IPF) was associated with the A-6 allele. This study examined the hypothesis that the homozygous CC genotype at -20 and the AA genotype at -6 would confer worse measures of pulmonary function (measured by pulmonary function tests) in IPF.

METHODS

Multiple logistic regression analysis was applied to a NIH Lung Tissue Research Consortium cohort and a Spanish cohort, while also adjusting for covariates to determine the effects of these SNPs on measures of pulmonary function.

RESULTS

Analysis demonstrated that the CC genotype at -20 was strongly associated with reduced diffusing capacity in males in both cohorts (p = 0.0028 for LTRC and p = 0.017 for the Spanish cohort). In females, the AA genotype was significantly associated with lower FVC (p = 0.0082) and V alv (p = 0.022). In males, the haplotype CA at -20 and -6 in AGT was also strongly associated with reduced diffusing capacity in both cohorts.

CONCLUSIONS

This study is the first to demonstrate an association of AGT polymorphisms (-20A > C and -6G > A) with lower measures of pulmonary function in IPF. It is also the first to relate the effect of gender in lung fibrosis with polymorphisms in AGT.

Angiotensinogen gene transcription in pulmonary fibrosis

An established body of literature supports the hypothesis that activation of a local tissue angiotensin (ANG) system in the extravascular tissue compartment of the lungs is required for lung fibrogenesis. Transcriptional activation of the angiotensinogen (AGT) gene is believed to be a critical and necessary step in this activation. This paper summarizes the data in support of this theory and discusses transcriptional regulation of AGT, with an emphasis on lung AGT synthesis as a determinant of fibrosis severity. Genetic data linking AGT polymorphisms to the severity of disease in Idiopathic Pulmonary Fibrosis are also discussed.

Angiotensinogen gene haplotype is associated with the prevalence of Japanese non-alcoholic steatohepatitis

AIM

  Non-alcoholic steatohepatitis (NASH) patients frequently have hypertension, which is considered to be an important predictive factor for the subsequent development of hepatic fibrosis. The renin-angiotensin system is also known to contribute to the progression of NASH. Various types of functional single-nucleotide polymorphisms (SNPs) involved in the development of NASH have been proposed. Angiotensinogen (AGT) gene SNPs related to cardiovascular diseases have been reported. We aimed to evaluate the involvement of the AGT gene haplotype in Japanese NASH patients.

METHODS

  Previously described genotypes of SNPs of the AGT gene, rs4762 C/T polymorphism (T207M), rs699 C/T polymorphism (T268M), and rs7079 C/A polymorphism (C11537A), were determined in 124 Japanese biopsy-proven NASH patients and 150 healthy volunteers (controls).

RESULTS

  The allele and genotype frequencies in rs4762 and rs699 SNPs in NASH patients were similar to those in controls, while the frequency of the A allele and A/- genotype in rs7079 SNPs were much higher in NASH patients than in controls. In addition, the 3-SNP haplotype CTA was significantly over-represented in NASH patients compared with controls. Regarding clinical features of NASH patients, diastolic blood pressures in patients with the CTA/- genotype were much higher than in patients with other genotypes.

CONCLUSIONS

  We found a 3-SNP haplotype of the AGT gene that is involved in the development of NASH and influences hypertension in NASH patients. These results provide new insight into the therapy of NASH patients with the CTA haplotype using ACE inhibitors or angiotensin II type 1 receptor blockers.

Fcγ receptor IIIb (CD16b) polymorphisms are associated with susceptibility to idiopathic pulmonary fibrosis

An excess of neutrophils in the alveoli and lung interstitium has been described in idiopathic pulmonary fibrosis (IPF). Engagement of neutrophil Fcγ receptors with IgG complexes may contribute to the pathogenesis of IPF. The neutrophil FcγRIIIb receptor occurs in two codominantly expressed allelic variants, NA1 and NA2, which exhibit different binding affinities for IgG1 and IgG3 subclasses. The aim of this study was to investigate whether FcγRIIIb genotype is associated with IPF susceptibility or disease progression. In a case-control study we compared the distribution of FcγRIIIb NA1/2 polymorphisms in 142 patients with IPF and in 218 controls using allele-specific PCR amplification. Significant skewing in the distribution of FcγRIIIb genotypes was observed between patients with IPF and control subjects. In the IPF cohort, there was higher frequency of the NA1/NA1 genotype (0.19 vs. 0.07), and lower NA2/NA2 frequency (0.31 vs. 0.50; χ(2) = 17.71, df = 2, P < 0.001). The overall frequency of the NA1 allele was increased in IPF patients compared to controls (0.44 vs. 0.29; P < 0.0001, odds ratio [OR] = 1.93, 95% confidence interval [CI] = 1.42-2.64). Heterozygotes and homozygotes of the NA1 allele were at higher risk of developing IPF (OR = 2.19, 95% CI = 1.40-3.41, P = 0.0005), whereas the NA2 allele was protective against IPF (OR = 0.34, 95% CI = 0.17-0.65, P = 0.0014). There was no association of FcγRIIIb genotype with disease progression as assessed by serial lung function measurements. FcγRIIIb NA1/2 polymorphisms are associated with IPF disease susceptibility. These results support a role for immunological mechanisms contributing to IPF pathogenesis.

Association of FcγRIIa R131H polymorphism with idiopathic pulmonary fibrosis severity and progression

Background

A significant genetic component has been described for idiopathic pulmonary fibrosis (IPF). The R131H (rs1801274) polymorphism of the IgG receptor FcγRIIa determines receptor affinity for IgG subclasses and is associated with several chronic inflammatory diseases. We investigated whether this polymorphism is associated with IPF susceptibility or progression.

Methods

In a case-control study, we compared the distribution of FcγRIIa R131H genotypes in 142 patients with IPF and in 218 controls using allele-specific PCR amplification.

Results

No differences in the frequency of FcγRIIa genotypes were evident between IPF patients and control subjects. However, significantly impaired pulmonary function at diagnosis was observed in HH compared to RR homozygotes, with evidence of more severe restriction (reduced forced vital capacity (FVC)) and lower diffusing capacity for carbon monoxide (DL_CO). Similarly, increased frequency of the H131 allele was observed in patients with severe disease (DL_CO < 40% predicted) (0.53 vs. 0.38; p = 0.03). Furthermore, the H131 allele was associated with progressive pulmonary fibrosis as determined by > 10% drop in FVC and/or > 15% fall in DL_CO at 12 months after baseline (0.48 vs. 0.33; p = 0.023).

Conclusions

These findings support an association between the FcγRIIa R131H polymorphism and IPF severity and progression, supporting the involvement of immunological mechanisms in IPF pathogenesis.

The angiotensin-converting enzyme 2/angiogenesis-(1-7)/Mas axis confers cardiopulmonary protection against lung fibrosis and pulmonary hypertension

RATIONALE

An activated vasoconstrictive, proliferative, and fibrotic axis of the renin angiotensin system (angiotensin-converting enzyme [ACE]/angiotensin [Ang]II/AngII type 1 receptor) has been implicated in the pathophysiology of pulmonary fibrosis (PF) and pulmonary hypertension (PH). The recent discovery of a counterregulatory axis of the renin angiotensin system composed of ACE2/Ang-(1-7)/Mas has led us to examine the role of this vasoprotective axis on such disorders.

OBJECTIVES

We hypothesized that Ang-(1-7) treatment would exert protective effects against PF and PH.

METHODS

Lentiviral packaged Ang-(1-7) fusion gene or ACE2 cDNA was intratracheally administered into the lungs of male Sprague Dawley rats. Two weeks after gene transfer, animals received bleomycin (2.5 mg/kg). In a subsequent study, animals were administered monocrotaline (MCT, 50 mg/kg).

MEASUREMENTS AND MAIN RESULTS

In the PF study, bleomycin administration resulted in a significant increase in right ventricular systolic pressure, which was associated with the development of right ventricular hypertrophy. The lungs of these animals also exhibited excessive collagen deposition, decreased expression of ACE and ACE2, increased mRNA levels for transforming growth factor β and other proinflammatory cytokines, and increased protein levels of the AT₁R. Overexpression of Ang-(1-7) significantly prevented all the above-mentioned pathophysiological conditions. Similar protective effects were also obtained with ACE2 overexpression. In the PH study, rats injected with MCT developed elevated right ventricular systolic pressure, right ventricular hypertrophy, right ventricular fibrosis, and pulmonary vascular remodeling, all of which were attenuated by Ang-(1-7) overexpression. Blockade of the Mas receptor abolished the beneficial effects of Ang-(1-7) against MCT-induced PH.

CONCLUSIONS

Our observations demonstrate a cardiopulmonary protective role for the ACE2/Ang-(1-7)/Mas axis in the treatment of lung disorders.

Polymorphisms in thrombophilia and renin-angiotensin system pathways, preterm delivery, and evidence of placental hemorrhage

OBJECTIVE

The purpose of this study was to analyze functional polymorphisms in candidate genes (methylenetetrahydrofolate reductase [MTHFR]677C>T, MTHFR1298A>C, factor 5 1691G>A [FVL], and angiotensinogen (AGT)-6G>A) in relation to a hypothesized placental hemorrhage pathway to preterm delivery (PTD).

STUDY DESIGN

We assessed maternal genotypes, pregnancy outcomes, and placental pathologic evidence among 560 white and 399 black women who were recruited at mid trimester into a prospective cohort study (1998-2004). Odds of dominant genotypes were calculated for PTDs with (n = 56) or without (n = 177) evidence of placental hemorrhage (referent = term) with the use of race-stratified polytomous logistic regression models.

RESULTS

Among white women, FVL GA/AA and AGT(-6) GA/AA were both associated with hemorrhage-related PTDs (odds ratio [OR], 4.8; 95% confidence interval [CI], 1.6-14.2 and OR, 3.8; 95% CI, 1.3-10.5, respectively), but not other PTDs (ORs, 1.2 and 0.9, respectively). FVL GA/AA was associated with placental abruption (OR, 5.8; 95% CI, 1.1-30) among white women. All results were null for MTHFR genotypes.

CONCLUSION

FVL and AGT variant genotypes were associated specifically with hemorrhage-related PTDs.

Endomysial fibrosis in Duchenne muscular dystrophy: a marker of poor outcome associated with macrophage alternative activation

There is considerable interindividual variability in motor function among patients with Duchenne muscular dystrophy (DMD); moreover, pathogenetic mechanisms of motor dysfunction in DMD are not understood. Using multiparametric analysis, we correlated initial histologic alterations in quadriceps muscle biopsies from 25 steroid therapy-free patients with DMD with 13 relevant clinical features assessed by a single clinical team during a long-term period (mean, >10 years). There was no residual muscle dystrophin by immunohistochemistry and Western blot analysis in the biopsies. Myofiber size, hypercontracted fibers, necrotic/basophilic fibers, endomysial and perimysial fibrosis, and fatty degeneration were assessed by morphometry. Endomysial fibrosis was the only myopathologic parameter that significantly correlated with poor motor outcome as assessed by quadriceps muscle strength, manual muscle testing of upper and lower limbs at 10 years, and age at ambulation loss (all p<0.002). Motor outcome and fibrosis did not correlate with genotype. Myofibers exhibited oxidative stress-induced protein alterations and became separated from capillaries by fibrosis that was associated with both increase of CD206+ alternatively activated macrophages and a relative decrease of CD56+ satellite cells (both p<0.0001). This study provides a strong rationale for antifibrotic therapeutic strategies in DMD and supports the view that alternatively activated macrophages that are known to inhibit myogenesis while promoting cellular collagen production play a key role in myofibrosis.

JunD and HIF-1alpha mediate transcriptional activation of angiotensinogen by TGF-beta1 in human lung fibroblasts

Earlier work showed that TGF-beta1 potently increases angiotensinogen (AGT) gene mRNA in primary human lung fibroblasts. Here the mechanism of TGF-beta1-induced AGT expression was studied in the IMR90 human lung fibroblast cell line. The increase in AGT mRNA induced by TGF-beta1 was completely blocked by actinomycin-D. TGF-beta1 increased the activity of a full-length human AGT promoter-luciferase reporter (AGT-LUC) but did not alter AGT mRNA half-life. Serial deletion analyses revealed that 67% of TGF-beta-inducible AGT-LUC activity resides in a small domain of the AGT core promoter; this domain contains binding sites for hypoxia-inducible factor (HIF)-1 and activation protein-1 (AP-1) transcription factors. TGF-beta1 increased HIF-1alpha protein abundance and the activity of a hypoxia-responsive element reporter; overexpression of HIF-1 increased basal AGT-LUC activity. Both oligonucleotide pulldown and chromatin immunoprecipitation assays revealed increased binding of JunD and HIF-1alpha to the AGT core promoter in response to TGF-beta1. TGF-beta1-inducible AGT-LUC was reduced by an AP-1 dominant negative or by mutation of the AP-1 site. Knockdown of either JunD or HIF-1alpha individually by siRNA partially reduced AGT-LUC. In contrast, simultaneous knockdown of both JunD and HIF-1alpha completely eliminated TGF-beta1-inducible AGT-LUC activity. These data suggest that TGF-beta1 up-regulates AGT transcription in human lung fibroblasts through a mechanism that requires both JunD and HIF-1alpha binding to the AGT core promoter. They also suggest a molecular mechanism linking hypoxia signaling and fibrogenic stimuli in the lungs.