Angiotensin II-induced pulmonary edema in a rabbit model

Angiotensin-converting enzyme 1 gene polymorphisms in patients with systemic sclerosis-associated interstitial lung disease: a single centre retrospective observational study

Angiotensin-converting enzyme (ACE) 1 gene polymorphisms have been associated with vascular permeability, alveolar endothelial dysfunction and fibroblast proliferation and have been studied in pulmonary diseases such as COPD and idiopathic pulmonary fibrosis. Similar mechanisms of ACE 1 polymorphisms have been seen in patients with systemic sclerosis-associated interstitial lung disease (SSc-ILD). We are presenting a retrospective observational study in patients with SSc-ILD and analysing the association of ACE 1 gene polymorphisms (DD, II and ID) with the features of SSc, changes in pulmonary function tests (PFTs) and lung HRCT over three different periods of time (at the time of the diagnosis, 5 and 10 years after the diagnosis). The aim of the study was to determine whether ACE 1 gene polymorphisms have an effect on the severity of SSc-ILD. We found no statistically significant differences in the development and severity of SSc-ILD and changes in PFTs between subgroups of ACE 1 gene polymorphism over the analysed periods (at the time of diagnosis HRCT changes p = 0.270, FEV1 p = 0.483, FVC p = 0.497, DLco p = 0.807, after 5 years HRCT changes p = 0.163, FEV1 p = 0.551, FVC p = 0.362, DLco p = 0.620 and 10 years of follow-up HRCT changes p = 0.853, FEV1 p = 0.589, FVC p = 0.328, DLco p = 0.992). However, patients with the ID genotype showed a significant reduction in FEV1 after 10 years of follow-up in comparison to baseline levels (91.0 (IR 80.0-105.0) at the time of diagnosis and 84.0 (IR 69.0-99.0) after 10 years, p = 0.014). Our study suggests that ACE 1 gene polymorphisms do not have a role in the severity of SSc-ILD. Further studies are needed to explain the exact role of ACE 1 gene polymorphisms in SSc-ILD and SSc in general.

Pharmacologic therapies of ARDS: From natural herb to nanomedicine

Acute respiratory distress syndrome (ARDS) is a common critical illness in respiratory care units with a huge public health burden. Despite tremendous advances in the prevention and treatment of ARDS, it remains the main cause of intensive care unit (ICU) management, and the mortality rate of ARDS remains unacceptably high. The poor performance of ARDS is closely related to its heterogeneous clinical syndrome caused by complicated pathophysiology. Based on the different pathophysiology phases, drugs, protective mechanical ventilation, conservative fluid therapy, and other treatment have been developed to serve as the ARDS therapeutic methods. In recent years, there has been a rapid development in nanomedicine, in which nanoparticles as drug delivery vehicles have been extensively studied in the treatment of ARDS. This study provides an overview of pharmacologic therapies for ARDS, including conventional drugs, natural medicine therapy, and nanomedicine. Particularly, we discuss the unique mechanism and strength of nanomedicine which may provide great promises in treating ARDS in the future.

Endothelial Damage in Acute Respiratory Distress Syndrome

The pulmonary endothelium is a metabolically active continuous monolayer of squamous endothelial cells that internally lines blood vessels and mediates key processes involved in lung homoeostasis. Many of these processes are disrupted in acute respiratory distress syndrome (ARDS), which is marked among others by diffuse endothelial injury, intense activation of the coagulation system and increased capillary permeability. Most commonly occurring in the setting of sepsis, ARDS is a devastating illness, associated with increased morbidity and mortality and no effective pharmacological treatment. Endothelial cell damage has an important role in the pathogenesis of ARDS and several biomarkers of endothelial damage have been tested in determining prognosis. By further understanding the endothelial pathobiology, development of endothelial-specific therapeutics might arise. In this review, we will discuss the underlying pathology of endothelial dysfunction leading to ARDS and emerging therapies. Furthermore, we will present a brief overview demonstrating that endotheliopathy is an important feature of hospitalised patients with coronavirus disease-19 (COVID-19).

Good or bad: Application of RAAS inhibitors in COVID-19 patients with cardiovascular comorbidities

The coronavirus disease 2019 (COVID-19) pandemic is caused by a newly emerged coronavirus (CoV) called Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2). COVID-19 patients with cardiovascular disease (CVD) comorbidities have significantly increased morbidity and mortality. The use of angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor type 1 blockers (ARBs) improve CVD outcomes; however, there is concern that they may worsen the prognosis of CVD patients that become infected with SARS-CoV-2 because the virus uses the ACE2 receptor to bind to and subsequently infect host cells. Thus, some health care providers and media sources have questioned the continued use of ACE inhibitors and ARBs. In this brief review, we discuss the effect of ACE inhibitor-induced bradykinin on the cardiovascular system, on the renin-angiotensin-aldosterone system (RAAS) regulation in COVID-19 patients, and analyze recent clinical studies regarding patients treated with RAAS inhibitors. We propose that the application of RAAS inhibitors for COVID-19 patients with CVDs may be beneficial rather than harmful.

Beta-Adrenergic Blockers as a Potential Treatment for COVID-19 Patients

More than 15 million people have been affected by coronavirus disease 2019 (COVID-19) and it has caused 640 016 deaths as of July 26, 2020. Currently, no effective treatment option is available for COVID-19 patients. Though many drugs have been proposed, none of them has shown particular efficacy in clinical trials. In this article, the relationship between the Adrenergic system and the renin-angiotensin-aldosterone system (RAAS) is focused in COVID-19 and a vicious circle consisting of the Adrenergic system-RAAS-Angiotensin converting enzyme 2 (ACE2)-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (which is referred to as the "ARAS loop") is proposed. Hyperactivation of the ARAS loop may be the underlying pathophysiological mechanism in COVID-19, and beta-adrenergic blockers are proposed as a potential treatment option. Beta-adrenergic blockers may decrease the SARS-CoV-2 cellular entry by decreasing ACE2 receptors expression and cluster of differentiation 147 (CD147) in various cells in the body. Beta-adrenergic blockers may decrease the morbidity and mortality in COVID-19 patients by preventing or reducing acute respiratory distress syndrome (ARDS) and other complications. Retrospective and prospective clinical trials should be conducted to check the validity of the hypothesis. Also see the video abstract here https://youtu.be/uLoy7do5ROo.

Angiotensin-converting enzyme insertion/deletion gene polymorphism in Egyptian children with CAP: A case-control study

BACKGROUND

Community-acquired pneumonia (CAP) is a major cause of childhood morbidity and mortality worldwide. The angiotensin-converting enzyme (ACE) gene is a potential candidate gene for CAP risk.

OBJECTIVES

In this study, we aimed to investigate whether the ACE insertion/deletion (I/D) polymorphism (rs4340) could be a genetic marker for CAP susceptibility in Egyptian children, and we also measured the serum ACE level to assess its relation to such polymorphism.

METHODS

This was a prospective case-control study included 300 patients with CAP, and 300 age, gender, and ethnicity matched healthy controls. The ACE I/D polymorphism (rs4340) at intron 16 was genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), while the serum ACE levels were measured by ELISA.

RESULTS

Compared to the controls subjects, the frequencies of the ACE DD genotype and D allele were overrepresented in patients with CAP (OR = 3.05; [95%CI: 2.14-4.35] for the DD genotype; P < 0.001) and (OR: 1.8; [95%CI: 1.42-2.29]; for the D allele; P < 0.01, respectively). Patients with the DD genotype had significantly higher mean serum ACE levels (45.6 ± 11.4 U/L) compared to those with ID genotype (36.5 ± 8.3 U/L) and II genotype (21.6 ± 5.7 U/L); P < 0.01, respectively.

CONCLUSION

The ACE I/D polymorphism (rs4340) may contribute to the genetic susceptibility of CAP in Egyptian children. The ACE D allele and DD genotype were associated with higher serum ACE levels among studied CAP patients.

Pathobiology of acute respiratory distress syndrome

The unique characteristics of pulmonary circulation and alveolar-epithelial capillary-endothelial barrier allow for maintenance of the air-filled, fluid-free status of the alveoli essential for facilitating gas exchange, maintaining alveolar stability, and defending the lung against inhaled pathogens. The hallmark of pathophysiology in acute respiratory distress syndrome is the loss of the alveolar capillary permeability barrier and the presence of protein-rich edema fluid in the alveoli. This alteration in permeability and accumulation of fluid in the alveoli accompanies damage to the lung epithelium and vascular endothelium along with dysregulated inflammation and inappropriate activity of leukocytes and platelets. In addition, there is uncontrolled activation of coagulation along with suppression of fibrinolysis and loss of surfactant. These pathophysiological changes result in the clinical manifestations of acute respiratory distress syndrome, which include hypoxemia, radiographic opacities, decreased functional residual capacity, increased physiologic deadspace, and decreased lung compliance. Resolution of acute respiratory distress syndrome involves the migration of cells to the site of injury and re-establishment of the epithelium and endothelium with or without the development of fibrosis. Most of the data related to acute respiratory distress syndrome, however, originate from studies in adults or in mature animals with very few studies performed in children or juvenile animals. The lack of studies in children is particularly problematic because the lungs and immune system are still developing during childhood and consequently the pathophysiology of pediatric acute respiratory distress syndrome may differ in significant ways from that seen in acute respiratory distress syndrome in adults. This article describes what is known of the pathophysiologic processes of pediatric acute respiratory distress syndrome as we know it today while also presenting the much greater body of evidence on these processes as elucidated by adult and animal studies. It is also our expressed intent to generate enthusiasm for larger and more in-depth investigations of the mechanisms of disease and repair specific to children in the years to come.

Pharmacological therapies for acute respiratory distress syndrome

PURPOSE OF REVIEW

Despite recent advances in the management of patients with acute respiratory distress syndrome (ARDS) by using protective ventilator strategies, the mortality rate of ARDS remains high. The complexity of the pathogenesis and the heterogeneity of coexisting diseases in patients with ARDS require critical care physicians and researchers to search for multiple therapeutic approaches in order to further improve patient outcome. This review article therefore focuses on the recent studies in the field of pharmacological intervention in ARDS.

RECENT FINDINGS

A number of approaches for pharmacological intervention have been evaluated in patients with ARDS, but most of them failed to reduce mortality or improve outcomes despite some promising observations seen in preclinical studies. Prior methods such as nitric oxide inhalation, neuromuscular blocking agents and corticosteroids may still have a place in the treatment, while novel therapeutic approaches including the use of angiotensin-converting enzyme inhibitors, statins and stem cells are currently under investigation.

SUMMARY

Overall, there is no proven pharmacological therapy in ARDS, but some pharmacological interventions were associated with beneficial effects in certain subgroups of patients depending on the cause, underlying diseases, the concurrent supportive therapies and timing. Further clinical trials are warranted to assess multiple outcome measurement of the promising pharmacological interventions in selected patients with ARDS.

The effect of endogenous angiotensin II on alveolar fluid clearance in rats with acute lung injury

BACKGROUND

In acute lung injury (ALI), angiotensin II (Ang II) plays a vital role in the stimulation of pulmonary permeability edema formation through the angiotensin type 1 (AT1) receptor. The effect of Ang II on alveolar fluid clearance (AFC) in ALI remains unknown.

METHODS

Sprague Dawley rats were anesthetized and intratracheally injected with 1 mg⁄kg lipopolysaccharide (LPS), while control rats received saline. The AT1 receptor antagonist ZD7155 was injected intraperitoneally (10 mg⁄kg) 30 min before LPS administration. The lungs were isolated for AFC measurement, and alpha-epithelial sodium channel (ENaC) messenger RNA and protein expression were detected by reverse-transcription polymerase chain reaction and Western blot.

RESULTS

LPS-induced ALI caused an increase in Ang II levels in plasma and lung tissue but a decrease in AFC. The time course of Ang II levels paralleled that of AFC. Pretreatment with ZD7155 prevented ALI-induced reduction of AFC. ZD7155 also reversed the ALI-induced reduction of beta-ENaC and gamma-ENaC levels, and further decreased alpha-ENaC levels.

CONCLUSIONS

These findings suggest that endogenous Ang II inhibits AFC and dysregulates ENaC expression via AT1 receptors, which contribute to alveolar filling and pulmonary edema in LPS-induced ALI.

Association between insertion/deletion polymorphism in angiotensin-converting enzyme gene and acute lung injury/acute respiratory distress syndrome: a meta-analysis

BACKGROUND

A previous meta-analysis reported a positive association between an insertion/deletion (I/D) polymorphism in the angiotensin-converting enzyme gene (ACE) and the risk of acute lung injury (ALI)/acute respiratory distress syndrome (ARDS). Here, we updated this meta-analysis and additionally assessed the association of this polymorphism with ALI/ARDS mortality.

METHODS

We searched electronic databases through October 2011 for the terms "angiotensin-converting enzyme gene", "acute lung injury", and "acute respiratory distress syndrome," and reviewed all studies that reported the relationship of the I/D polymorphism in ACE with ALI/ARDS in humans. Seven studies met the inclusion criteria, comprising 532 ALI/ARDS patients, 3032 healthy controls, and 1432 patients without ALI/ARDS. We used three genetic models: the allele, dominant, and recessive models.

RESULTS

The ACE I/D polymorphism was not associated with susceptibility to ALI/ARDS for any genetic model. However, the ACE I/D polymorphism was associated with the mortality risk of ALI/ARDS in Asian subjects ( P(allele) < 0.0001, P(dominant) = 0.001, P(recessive) = 0.002). This finding remained significant after correction for multiple comparisons.

CONCLUSIONS

There is a possible association between the ACE I/D polymorphism genotype and the mortality risk of ALI/ARDS in Asians.

Angiotensin-converting enzyme insertion/deletion polymorphism associated with acute respiratory distress syndrome among caucasians

Studies investigating the association between angiotensin-converting enzyme (ACE) insertion/deletion polymorphisms and the risk of acute respiratory distress syndrome (ARDS) report conflicting results. The objective of the present study was to summarize quantitatively the evidence for such a relationship. Two investigators independently searched the MEDLINE (January 1966 - October 2009) and EMBASE (January 1980 - October 2009) databases. This meta-analysis included six case-control studies, which included 514 ARDS cases and 2619 controls. The combined results based on all studies showed that patients with ARDS had a significantly higher frequency of the ACE deletion/deletion (DD) genotype (odds ratio [OR] 1.56; 95% confidence interval [CI] 1.22, 2.00) than controls. When stratifying for race, no significant differences in genotype distribution were found except that Caucasian patients with ARDS had a significantly higher frequency of the DD genotype (OR 1.65; 95% CI 1.27, 2.13) than controls. This meta-analysis suggests that ACE insertion/deletion polymorphisms may be associated with ARDS among Caucasians.

Hypertension study in anaesthetized rabbits: protocol proposal for AT1 antagonists screening

INTRODUCTION

The aim of this study was to establish an optimized fast and safe protocol for the pharmacological screening of AT(1) antagonists.

MATERIALS AND METHODS

The pharmaceutical prototype AT(1) antagonist losartan, its active metabolite EXP3174 and the synthetic compound MMK1 were analysed in order to validate the protocol. Ang II was continuously infused while the animals received the drugs in two procedures.

RESULTS

In the post-treatment procedure drugs were administered either in a single bolus dose or in a sequential manner. When losartan was administered in a single bolus dose, efficacy was evident until the 7th min (p=0.012) whilst EXP3174 infusion extended the efficiency up to the end of the study (p=0.006). In addition, the sequential injections of losartan prolonged the inhibitory time interval until the end of the study (p=0.045). In the pre-treatment procedure, results suggested a dose-dependent inhibitory effect for both antagonists. The pressor response to Ang II was unchanged after MMK1 administration either in the post- or in the pre-treatment mode.

CONCLUSIONS

The proposed protocol appears to be safe, simple and fast for the pharmacological screening of AT(1) antagonists and enables the evaluation of new antagonists using lower doses than any other reported in the literature.

The pathogenetic and prognostic value of biologic markers in acute lung injury

Over the past 2 decades, measurement of biomarkers in both the airspaces and plasma early in the course of acute lung injury has provided new insights into the mechanisms of lung injury. In addition, biologic markers of cell-specific injury, acute inflammation, and altered coagulation correlate with mortality from acute lung injury in several single center studies as well as in multicenter clinical trials. To date, biomarkers have been measured largely for research purposes. However, with improved understanding of their role in the pathogenesis of acute lung injury, biomarkers may play an important role in early detection of lung injury, risk stratification for clinical trials, and, ultimately, tailoring specific therapies to individual patients. This article provides a review of biologic markers in acute lung injury, with an emphasis on recent analysis of results from multicenter clinical trials.

Angiotensin-converting enzyme D allele does not influence susceptibility to acute hypoxic respiratory failure in children

OBJECTIVE

The D allele of the I/D polymorphism in the angiotensin-converting enzyme (ACE) gene has been associated with an increased risk of ARDS in critically ill adults and severity of bronchopulmonary dysplasia in pre-term infants. We hypothesised that the presence of the hypoxia-associated ACE D allele would increase susceptibility to acute hypoxic respiratory failure (AHRF) in a cohort of critically ill children.

DESIGN AND SETTING

Single-centre prospective observational cohort study.

PATIENTS

Children under 16 years of age requiring admission to a tertiary general PICU.

MEASUREMENTS AND RESULTS

A total of 216 Caucasian patients were enrolled. Thirty (13.9%) children developed AHRF and 13 were diagnosed with ARDS (6.0%). There was no significant difference in ACE D allele frequency between patient groups with or without AHRF (0.53 vs. 0.54).

CONCLUSIONS

Variation in ACE activity does not influence the development of paediatric AHRF. This may reflect a different pathogenesis from adult ARDS.

Endothelial pathomechanisms in acute lung injury

Acute lung injury (ALI) and its most severe extreme the acute respiratory distress syndrome (ARDS) refer to increased-permeability pulmonary edema caused by a variety of pulmonary or systemic insults. ALI and in particular ARDS, are usually accompanied by refractory hypoxemia and the need for mechanical ventilation. In most cases, an exaggerated inflammatory and pro-thrombotic reaction to an initial stimulus, such as systemic infection, elicits disruption of the alveolo-capillary membrane and vascular fluid leak. The pulmonary endothelium is a major metabolic organ promoting adequate pulmonary and systemic vascular homeostasis, and a main target of circulating cells and humoral mediators under injury; pulmonary endothelium is therefore critically involved in the pathogenesis of ALI. In this review we will discuss mechanisms of pulmonary endothelial dysfunction and edema generation in the lung with special emphasis on the interplay between the endothelium, the immune and hemostatic systems, and highlight how these principles apply in the context of defined disorders and specific insults implicated in ALI pathogenesis.

The discovery of angiotensin-converting enzyme 2 and its role in acute lung injury in mice

During several months of 2002, severe acute respiratory syndrome (SARS) caused by SARS-coronavirus (SARS-CoV) spread rapidly from China throughout the world, causing more than 800 deaths due to the development of acute respiratory distress syndrome (ARDS), which is the severe form of acute lung injury (ALI). Interestingly, a novel homologue of angiotensin-converting enzyme, termed angiotensin-converting enzyme 2 (ACE2), has been identified as a receptor for SARS-CoV. Angiotensin-converting enzyme and ACE2 share homology in their catalytic domain and provide different key functions in the renin-angiotensin system (RAS). Angiotensin-converting enzyme cleaves angiotensin I to generate angiotensin II, which is a key effector peptide of the system and exerts multiple biological functions, whereas ACE2 reduces angiotensin II levels. Importantly, our recent studies using ACE2 knockout mice have demonstrated that ACE2 protects murine lungs from ARDS. Furthermore, SARS-CoV infections and the Spike protein of the SARS-CoV reduce ACE2 expression. Notably, injection of SARS-CoV Spike into mice worsens acute lung failure in vivo, which can be attenuated by blocking the renin-angiotensin pathway, suggesting that the activation of the pulmonary RAS influences the pathogenesis of ALI/ARDS and SARS.

Angiotensin-converting enzyme insertion/deletion polymorphism is not associated with susceptibility and outcome in sepsis and acute respiratory distress syndrome

OBJECTIVE

The insertion/deletion (I/D) of a 289 base pair Alu repeat sequence polymorphism in the angiotensin-converting enzyme gene (ACE) has been shown to predict susceptibility and outcome in the acute respiratory distress syndrome (ARDS). We hypothesized that the I/D polymorphism also confers susceptibility to sepsis and is a predisposing factor for morbidity and mortality of patients with severe sepsis.

DESIGN AND SETTING

Case-control study including 212 consecutive patients fulfilling criteria for severe sepsis admitted to a Spanish network of postsurgical and critical care units, and 364 population-based controls. Susceptibility to severe sepsis was evaluated as primary outcome; mortality in severe sepsis, susceptibility to sepsis-induced ARDS, and mortality in sepsis-induced ARDS were examined as secondary outcomes. An additive model of inheritance in which patients were classified into three genotype groups (II, ID, and DD) was used for association testing.

MEASUREMENTS AND RESULTS

Genotype and allele frequencies of I/D were distributed similarly in all septic, ARDS, and non-ARDS patients and in population-based controls. ACE I/D polymorphism was not associated with severe sepsis susceptibility or mortality. The ACE I/D polymorphism was associated neither with sepsis-induced ARDS susceptibility (p=0.895) or mortality (p=0.950). These results remained nonsignificant when adjusted for other covariates using multiple logistic regression analysis or Kaplan-Meier estimates of 28-day survival.

CONCLUSIONS

Our data do not support an association of the ACE gene I/D polymorphism with susceptibility or mortality in severe sepsis or with sepsis-induced ARDS in Spanish patients.

The renin-angiotensin system in acute respiratory distress syndrome

Angiotensin-converting enzyme 2 (ACE2) counterbalances with ACE and functions as a negative regulator of the renin–angiotensin system (RAS). The importance of RAS in acute respiratory distress syndrome (ARDS) has recently re-emerged owing to the identification of ACE2 as a receptor for the SARS-coronavirus. Recent studies have demonstrated that ACE2 protects mice from acute lung injury as well as SARS-mediated lung injury. We review the role of the RAS, in particular ACE2, in the pathogenesis of ARDS.

Terry Delovitch – The John P. Robarts Research Institute, London, Ont., Canada

David Scott – University of Maryland School of Medicine, Baltimore, MD, USA

Expression and regulation of AT1 receptor in rat lung microvascular endothelial cell

BACKGROUND

The renin-angiotensin system is thought to be involved in the development and progression of vascular endothelium inflammation, thereby contributing to vascular endothelium injury. To clarify the role of angiotensin II (Ang II) in rat pulmonary microvascular endothelial cells (RPMVECs), we examined the expression and functional significance of angiotensin II (Ang II) receptors in normal and lipopolysacchride (LPS) treated RPMVECs.

METHODS

The expressions of Ang II type 1(AT(1)) and Ang II type 2 (AT(2)) receptors in cultured RPMVECs were identified by the reverse transcription-polymerase chain reaction (RT-PCR) technique, Western blot and (125)I-labeled [Sar(1),Ile(8)] Ang II binding assays. The RPMVECs were treated with LPS (0.1-100 microg/ml) and Ang II (10(-8)-10(-5) M) for 24 h, respectively. Next, RPMVECs were treated with 10 microg/ml LPS or 10(-7) M Ang II for various times (3, 6, 12, and 24 h). The mRNA and protein levels of, AT(1) and AT(2) receptors, were evaluated at 3, 6, 12, and 24 h, respectively.

RESULTS

The presence of specific Ang II binding sites in RPMVECs was found by Ang II saturated assays. RT-PCR revealed that only the AT(1) receptor mRNA is presented in RPMVECs. Western blot analysis of the RPMVECs protein extracts showed only one prominent band of the protein at approximately 41 KDa when probed with anti-AT(1) antibody and anti-AT(2) antibody. No AT(2) receptor mRNA and protein was detected. LPS treated cells resulted in an increase in the mRNA and protein levels of AT(1) receptor, whereas, Ang II treated cells showed a decrease in the mRNA and protein levels of AT(1) receptor.

CONCLUSIONS

We found that primary cultured RPMVECs expressed only AT(1) receptor, but not AT(2) receptor. LPS up-regulated the transcriptional and post-transcriptional expression of AT(1) receptor in RPMVECS; in contrast, Ang II treatment caused a reduction in the mRNA and protein of AT(1) receptor in a time-dependent manner.

The Angiotensin Converting Enzyme Insertion/Deletion polymorphism is not associated with an increased risk of death or bronchopulmonary dysplasia in ventilated very low birth weight infants

BACKGROUND

The ACE gene contains a polymorphism consisting of either the presence (insertion, I) or absence (deletion, D) of a 287 bp alu repeat in intron 16. The D allele is associated with increased ACE activity in both tissue and plasma. The DD genotype is associated with risk of developing ARDS and mortality. The frequency of the D allele is higher in patients with pulmonary fibrosis, sarcoidosis and berylliosis. The role of this polymorphism has not been studied in the development of BPD in the premature newborn.

METHODS

ACE I/D genotype was determined in 245 (194 African-American, 47 Caucasian and 4 Hispanic) mechanically ventilated infants weighing less than 1250 grams at birth and compared to outcome (death and/or development of BPD).

RESULTS

The incidence of the D allele in the study population was 0.58. Eighty-eight (35.9%) infants were homozygous DD, 107 (43.7%) were heterozygous ID and 50 (20.4%) were homozygous II. There were no significant differences between genotype groups with respect to ethnic origin, birth weight, gestation, or gender. There was no effect of the ACE I/D polymorphism on mortality or development of BPD (O2 on 28 days or 36 weeks PCA). Secondary outcomes (intraventricular hemorrhage and periventricular leukomalacia) similarly were not influenced by the ACE ID polymorphism.

CONCLUSIONS

The ACE I/D polymorphism does not significantly influence the development of BPD in ventilated infants less than 1250 grams.

Polymorphisms of renin-angiotensin system genes with high-altitude pulmonary edema in Japanese subjects

STUDY OBJECTIVES

The renin-angiotensin system (RAS), including angiotensin-converting enzyme (ACE) and angiotensin II type 1 receptor (AT(1)R), plays an important role in the pathogenesis of pulmonary hypertension, which is suggested to be critical in the development of high-altitude pulmonary edema (HAPE). Investigating the associations of the polymorphisms in the genes of RAS with HAPE is to elucidate the genetic background underlying this disease.

DESIGN

A cross-sectional, case-control study.

SETTING

Shinshu University Hospital, Matsumoto, Japan.

PARTICIPANTS

Forty-nine HAPE-susceptible (HAPE-s) subjects with a history of HAPE, and 55 healthy climbers with HAPE resistance (HAPE-r).

INTERVENTIONS

Twenty-one of 49 HAPE-s subjects underwent right cardiac catheterization.

MEASUREMENTS AND RESULTS

The insertion/deletion polymorphism in the ACE gene (ACE-I/D) was investigated by polymerase chain reaction (PCR). There was no significant difference of the distribution of the ACE-I/D polymorphism between the HAPE-s and HAPE-r groups. The A(1166)C and G(1517)T single-nucleotide polymorphisms (SNPs) in AT(1)R gene were investigated by the PCR following digested by corresponding restricted endonuclease enzymes. The distribution of the G(1517)T SNP was significantly different between the two groups (p = 0.012). The pulmonary hemodynamics of the 21 HAPE-s subjects were retrospectively examined. The pulmonary artery pressure (PAP), pulmonary vascular resistance (PVR), and PVR index (PVRI) were all significantly increased on hospital admission. Moreover, the PVR and PVRI were significantly higher in the HAPE-s subjects with D positivity than in the HAPE-s subjects with I positivity (PVR, p = 0.015; PVRI, p = 0.028), while the PAP did not show any significant difference between the two subgroups.

CONCLUSIONS

The ACE-I/D polymorphism is not associated with HAPE susceptibility in Japanese subjects. The AT(1)R gene polymorphisms may likely associate with HAPE susceptibility. The D allele of the ACE-I/D polymorphism probably contributes to the hyperresponsive PVR and PVRI to acute hypoxia.

Rapid Improvement of Acute Pulmonary Edema with Angiotensin Converting Enzyme Inhibitor under Hemodialysis in a Patient with Renovascular Disease

A 71-year-old man with bilateral renovascular disease was admitted to Hamamatsu University hospital because of appetite loss and acute shortness of breath due to acute pulmonary edema (APE) with accelerated hypertension and renal failure. Hypertension and APE were controlled by an angiotensin converting enzyme inhibitor (ACEI) and four sessions of hemodialysis with reduction of 1.8 kg bodyweight. Renal function was later stabilized and the patient required no ACEI or hemodialysis. A trial of right renal angioplasty 1 month after admission failed and renal function deteriorated (serum creatinine 7.1 mg/dL) with accelerated hypertension, gain of bodyweight and APE. Even after four sessions of hemodialysis with adequate reduction of bodyweight, APE was not controlled, but it rapidly improved after administration of an ACEI, without major bodyweight change. As no apparent cardiac dysfunction was evident, APE might have been caused by a direct action of angiotensin II on hyperpermeability in pulmonary capillaries. Blocking of angiotensin II should be considered in such patients even after introduction of hemodialysis.

[Gene polymorphism in intensive care patients. Is the course of disease predetermined?]

Molecular biology has revolutionized medicine by increasing our understanding of the pathophysiological mechanisms of disease and the ability to assess genetic risk. Individual differences in disease manifestation and course in intensive care medicine often cannot be explained by known phenotypic risk factors alone. Recent data suggest an association between specific genotypes and the risk of adverse clinical outcomes. This includes inflammatory responses (i.e. TNF-alpha, Il-10), infectious diseases such as pneumonia or meningitis, sepsis, ARDS, as well as the mortality of critically injured patients (polytrauma, severe brain trauma). Continued identification of such allotypes and haplotypes may not only provide insight as to why the response to treatment varies amongst individuals in the intensive care unit, but also may potentially decrease morbidity and mortality through improved risk assessment and the administration of prophylactic therapy.

Angiotensin converting enzyme insertion/deletion polymorphism is associated with susceptibility and outcome in acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is an often fatal condition for which a genetic predisposition is postulated, although no specific genes have been identified to date. Angiotensin converting enzyme (ACE) has a potential role in the pathogenesis of ARDS via effects on pulmonary vascular tone/permeability, epithelial cell survival, and fibroblast activation. Forty-seven percent of the variance in plasma ACE activity is accounted for by the ACE insertion/deletion (I/D) polymorphism, the D allele being associated with higher activity. We therefore hypothesized that the presence of the D allele would be associated with the development of ARDS. Ninety-six white patients fulfilling American/European Consensus Committee criteria for ARDS were genotyped for the ACE polymorphism together with individuals from three comparison groups: 88 white patients with non-ARDS respiratory failure ventilated in the intensive care unit (ICU), 174 ICU patients undergoing coronary artery bypass grafting, and 1,906 individuals from a general population group. DD genotype frequency was increased in the patients with ARDS compared with the ICU (p = 0.00008), coronary artery bypass grafting (p = 0.0009), and general population group (p = 0.00004) control groups and was significantly associated with mortality in the ARDS group (p < 0.02). These data suggest a potential role for renin-angiotensin systems in the pathogenesis of ARDS and for the first time implicate genetic factors in the development and progression of this syndrome.