Deletion allele of the angiotensin-converting enzyme gene as a risk factor for pneumonia in elderly patients

Restoring lung renin-angiotensin system balance through blood pressure control

Dysregulated renin-angiotensin system (RAS) signaling contributes to elevated blood pressure (BP), inflammation, and organ damage in systemic arterial hypertension (HTN). We have demonstrated that hypertensive humans and rats exhibit higher expression of classic RAS components and lower expression of counterregulatory RAS components in the lungs compared with normotensive counterparts. Here, we investigated whether BP control could restore the balance between classic [angiotensin I-converting enzyme 2 (ACE)/angiotensin II (Ang II)] and counterregulatory [angiotensin I-converting enzyme 2 (ACE2)/Ang (1-7)] RAS, thereby mitigating lung inflammation. Male spontaneously hypertensive rats (SHRs) were treated with either losartan or amlodipine, both of which effectively reduced BP. These interventions up-regulated lung Ace2 and down-regulated Ace gene expression. Pulmonary membrane ACE2 abundance and activity were higher in losartan- and amlodipine-treated SHRs than in vehicle-treated SHRs, whereas ACE protein and function remained unchanged. Drug-treated SHRs exhibited lower levels of lung Ang II and higher levels of Ang (1-7) than vehicle-treated SHRs. Rebalancing the pulmonary RAS remarkably reduced macrophage number and down-regulated pro-inflammatory genes in SHR lungs, with lower expression of lung pro-inflammatory genes correlating with lower circulating levels of ACE2. Serum analysis in healthy and hypertensive individuals supported these findings, showing higher ACE2 levels in uncontrolled compared with controlled hypertension and normotension. Collectively, these findings suggest that high blood pressure may induce lung inflammation via an ACE/ACE2 imbalance. BP control with either an RAS inhibitor or a calcium channel blocker rebalances RAS in SHR lungs and alleviates inflammation. Furthermore, this study provides a mechanistic link between inflammatory lung diseases (such as COVID-19) and hypertension as a major risk factor.

Impact of ACE I gene insertion/deletion, A-240T polymorphisms and the renin-angiotensin-aldosterone system on COVID-19 disease

BACKGROUND

The coronavirus disease 2019 (COVID-19) pandemic is driven by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, which has led to an enormous burden on patient morbidity and mortality. The renin-angiotensin-aldosterone system (RAAS) plays a significant role in various pulmonary diseases. Since SARS-CoV-2 utilizes the angiotensin-converting enzyme (ACE)2 receptor to exert its virulence and pathogenicity, the RAAS is of particular importance in COVID 19.

METHODS

Our preliminary study investigates retrospectively the influence of selected ACE-polymorphisms (I/D location at intron 16 in the B-coding sequence (rs4646994) and A-240T (rs 4291) at the A-promoter) as well as ACE1 and ACE2 serum levels on disease severity and the inflammatory response in inpatients and outpatients with COVID-19.

RESULTS

Our study included 96 outpatients and 88 inpatients (65.9% male, mean age 60 years) with COVID-19 from April to December 2020 in four locations in Germany. Of the hospitalized patients, 88.6% participants were moderately ill (n = 78, 64% male, median age 60 years), and 11.4% participants were severely ill or deceased (n = 10, 90% male, median age 71 years). We found no polymorphism-related difference in disease, in age distribution, time to hospitalization and time of hospitalization for the inpatient group. ACE1 serum levels were significantly increased in the DD compared to the II polymorphism and in the TT compared to the AA polymorphism. There was no significant difference in ACE 1 serum levels l between moderately ill and severely ill patients. However, participants requiring oxygen supplementation had significantly elevated ACE1 levels compared to participants not requiring oxygen, with no difference in ACE2 levels whereas females had significantly higher ACE2 levels.

CONCLUSIONS

Although there were no differences in the distribution of ACE polymorphisms in disease severity, we found increased proinflammatory regulation of the RAAS in patients with oxygen demand and increased serum ACE2 levels in women, indicating a possible enhanced anti-inflammatory immune response.

CLINICAL TRIAL REGISTRATION

PreBiSeCov: German Clinical Trials Register, DRKS-ID: DRKS00021591, Registered on 27th April 2020.

Renin-angiotensin-aldosterone system blockers and region-specific variations in COVID-19 outcomes: findings from a systematic review and meta-analysis

BACKGROUND AND AIMS

Coronavirus disease 2019 (COVID-19) has been observed to cause a high mortality in people with cardiometabolic diseases. Renin-angiotensin-aldosterone system (RAAS) blockers enhance the expression of ACE2, the binding receptor of SARS-CoV-2, and can enhance viral infectivity. We aim to provide a pooled estimate of the effect of RAAS blockers on COVID-19 outcomes.

METHODS

A literature search was performed using MEDLINE/PubMed, Google Scholar and preprint servers. All clinical studies analyzing the effect of RAAS blockers on clinical outcomes in COVID-19 patients were included in this study. Newcastle-Ottawa scale was used for quality assessment of studies. MOOSE checklist was followed. Mortality and severity outcomes were recorded as pooled odds ratio (OR) with 95% Confidence Intervals (CIs) and level of heterogeneity (I 2). Odds of mortality was the primary outcome. Odds of severity, hospitalization, intensive care unit (ICU) admission, mechanical ventilation (MV), steroid use and acute kidney injury were the secondary outcomes. Severity outcomes were chosen depending upon the definition used by respective authors. Country-specific variations and effects of individual class of RAAS blockers were also explored.

RESULTS

In total 47 published studies were included in the final analysis, with a total of 26,432 patients from 31 studies in mortality analysis and 20,127 patients from 23 studies in severity analysis. No increased risk of mortality [Pooled OR 0.91 (0.65-1.26), I 2 = 89%] or severity [Pooled OR 1.08 (0.79-1.46), I 2 = 88%] was seen with RAAS blockers. The drug class was protective in hypertension [pooled OR 0.63 (0.46-0.86), I 2 = 58%]. Severity of COVID-19 outcomes was high for Europeans [Pooled OR 2.08 (1.52-2.85), I 2 = 77%] and US patients [Pooled OR 1.87 (1.62-2.17)]. Nearly 4 times higher risk of hospitalization and 2 times higher risk of ICU admission and MV were observed in US patients. Class-wise, angiotensin receptor blocker use was associated with 1.6 times higher odds of severity, mainly in Europeans.

CONCLUSION

RAAS blockers are not associated with increased mortality in COVID-19 patients and should be continued in hypertensives. US and European patients are at higher risk of severe outcomes. Pharmacogenetic differences may explain the ethnicity-related variations.

PLAIN LANGUAGE SUMMARY

Effect of RAAS-blocking medicines on COVID-19 Background and aims: Higher deaths have been observed in COVID-19 patients who have other long-term diseases such as heart disease, diabetes, and high blood pressure. Many of these patients are prescribed a class of medicines called RAAS blockers (ramipril, telmisartan, etc). We studied whether the use of these medicines worsens the course of COVID-19 disease in these patients or causes excess deaths.Methods: We conducted a pooled analysis of 47 observational studies on the use of RAAS blocker drugs in COVID-19 patients.Results: We found that RAAS blockers do not cause excess deaths in patients with COVID-19. On the contrary, they have benefits if prescribed to those with high blood pressure. We also found that whereas European and US patients of COVID-19 taking these medicines had higher disease severity, this was not the case for Chinese patients.Conclusion: Theremay be some genetic and other factors responsible for differences by ethnicity.

Relationship Between Blood Pressure Levels on Admission and the Onset of Acute Pneumonia in Elderly Patients With Cerebral Hemorrhage

Background

We have reported that hypertension on admission in elderly patients with acute cerebral infarction is an independent predictor for the development of acute pneumonia. However, the relationship between blood pressure on admission owing to cerebral hemorrhage and the development of pneumonia has not been fully investigated. In this study, we evaluated the relationship between blood pressure levels on admission and the development of pneumonia in elderly patients with cerebral hemorrhage who were in the acute phase.

Methods

Subjects consisted of 117 elderly patients with cerebral hemorrhage who were in the acute phase and were emergently admitted to the Department of Geriatric Medicine, Kanazawa Medical University between 2005 and 2015 (59 males and 58 females, the mean age ± standard deviation (SD) of 80 ± 8 years, and the range of 65 - 98 years). Blood pressure levels on admission were classified into the following four groups: normal blood pressure/mild hypertension group (systolic blood pressure of < 160 mm Hg and diastolic blood pressure of < 100 mm Hg), moderate hypertension group (systolic hypertension of 160 - 179 mm Hg or diastolic blood pressure of 100 - 109 mm Hg), severe hypertension group (systolic hypertension of 180 - 199 mm Hg or diastolic blood pressure of 110 - 119 mmHg), and serious hypertension group (systolic blood pressure of ≥ 200 mm Hg or diastolic blood pressure of ≥ 120 mm Hg). Between the two groups (group of patients with acute pneumonia and group of those with absence of pneumonia), age, sex, body mass index (BMI), history of stroke, history of heart disease, chronic kidney disease, diabetes, dyslipidemia, prehypertension, blood pressure on admission, Japan Coma Scale (JCS) on admission, white blood cell count, C-reactive protein (CRP), albumin, bleeding sites, bleeding amount, and the presence or absence of centerline shift on brain computed tomography (CT) images were retrospectively evaluated. Furthermore, factors related to cerebral hemorrhage in the development of acute pneumonia in patients with cerebral hemorrhage were verified.

Results

Of the 117 patients, 30 (25.6%) had acute pneumonia. Age, sex, bleeding amount, midline shift, blood pressure classification on admission, JCS, white blood cell count, CRP, albumin, diabetes were adopted as confounding factors in the development of acute pneumonia. Results of multiple logistic regression analysis showed significant differences between these two groups in the following four items: CRP, white blood cell count, JCS, and blood pressure classification on admission. After adjustment of these confounding factors, the incidence of acute pneumonia in the blood pressure groups other than serious hypertension group was set as 1, and the odds ratio of pneumonia onset in serious hypertension group was revealed to be 5.54, with the 95% confidence interval of 1.49 - 20.6.

Conclusions

We found that serious hypertension on admission is a risk factor for the development of acute pneumonia in elderly patients with cerebral hemorrhage who are in the acute phase.

SARS-CoV-2 infections and COVID-19 mortalities strongly correlate with ACE1 I/D genotype

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COVID-19 infection is characterized by its prominent effect on specific ethnic group.

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SARS-CoV-2 cases/mortality were negatively associated with ACE1 II genotype.

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The ACE1 II genotype could be a predictive marker of SARS-CoV-2 risk and severity.

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) causes coronavirus disease 2019 (COVID-19). The relentless spread and pathogenicity of the virus have become a global public health emergency. One of the striking features of this pandemic is the pronounced impact on specific regions and ethnic groups. In particular, compared with East Asia, where the virus first emerged, SARS-CoV-2 has caused high rates of morbidity and mortality in Europe. This has not been experienced in past global viral infections, such as influenza, severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS) and is unique to SARS-CoV-2. For this reason, we investigated the involvement of genetic factors associated with SARS-CoV-2 infection with a focus on angiotensin-converting enzyme (ACE)-related genes, because ACE2 is a receptor for SARS-CoV-2. We found that the ACE1 II genotype frequency in a population was significantly negatively correlated with the number of SARS-CoV-2 cases. Similarly, the ACE1 II genotype was negatively correlated with the number of deaths due to SARS-CoV-2 infection. These data suggest that the ACE1 II genotype may influence the prevalence and clinical outcome of COVID-19 and serve as a predictive marker for COVID-19 risk and severity.

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.

Genetic Association Between CD143 rs4340 Polymorphism and Pneumonia risk: A Meta Analysis

rs4340 polymorphism at intron 16 of the angiotensin-converting enzyme (CD143) gene was reported to repress cough reflex by reducing bradykinin and substance P levels, thus increasing the likelihood to develop pneumonia. There have been different reports regarding the correlation of CD143 rs4340 genotypes with pneumonia risk, which prompted us to perform a meta-analysis to determine the elusive association.We combined multiple keywords to identify the studies addressing the association between CD143 rs4340 genotypes and pneumonia risk covered in the EMBASE, Google Scholar, PubMed, and CNKI databases. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to assess the risk of pneumonia. The fixed-effects model (FEM) was used.A total of 10 studies were analyzed in this quantitative analysis. We found a strong association between rs4340 single nucleotide polymorphism (SNP) and pneumonia risk using the recessive model (FEM: OR 1.33, 95% CI 1.13-1.57). A significantly increased risk was also indicated under the recessive model in Asian populations (FEM: OR 1.57, 95% CI 1.19-2.07), community-acquired pneumonia (CAP) (FEM: OR 1.31, 95% CI 1.08-1.60), and nosocomial pneumonia (NP) (FEM: OR 1.52, 95% CI 1.06-2.19).Our meta-analysis demonstrates that CD143 rs4340 polymorphism may represent a risk factor for pneumonia.

Increased risk of pneumonia associated with angiotensin-converting enzyme (CD143) rs4340 polymorphism

The study aims to investigate the genetic association between rs4340 polymorphism at intron 16 of the angiotensin-converting enzyme (CD143) gene and pneumonia predisposition. Electronic database of PubMed, Embase, and CNKI (China National Knowledge Infrastructure) was searched for the studies addressing the association between CD143 rs4340 genotypes and pneumonia risk. The odds ratio (OR) with its 95 % confidence interval (CI) was employed to estimate the association. In total, ten case-control studies, including 1239 pneumonia cases and 2400 healthy controls, met the inclusion criteria. Our results showed a significant association between rs4340 SNP and pneumonia risk using the recessive model (OR 1.43, 95 % CI 1.20-1.70). A significantly increased risk was also indicated under the recessive model in Asian populations (OR 1.63, 95 % CI 1.16-2.30), Caucasian populations (OR 1.34, 95 % CI 1.09-1.65), community-acquired pneumonia (OR 1.42, 95 % CI 1.16-1.75) rather than nosocomial pneumonia (OR 1.47, 95 % CI 0.97-2.23). However, further studies with gene-gene and gene-environmental interactions should be considered to confirm this association.

Angiotensin-converting enzyme I/D polymorphism is associated with pneumonia risk: a meta-analysis

BACKGROUND

Previous studies examined the association between angiotensin-converting enzyme (ACE) I/D polymorphism and pneumonia, but their results were inconsistent. Thus, a meta-analysis was performed to clarify the effect of ACE I/D polymorphism on pneumonia risk and pneumonia-related mortality.

METHODS

The PubMed, Embase, and Chinese National Knowledge Infrastructure (CNKI) databases were searched for relevant studies published up to 27 April 2013. Data were extracted and pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated.

RESULTS

Pooled analysis of 12 case-control studies (1431 cases and 3600 controls) showed that there was a significant association between ACE I/D polymorphism and pneumonia risk in a recessive genetic model (OR = 1.53, 95% CI 1.30-1.80, p < 0.00001). No significant association between ACE I/D polymorphism and mortality was observed (OR = 2.68, 95% CI 0.80-8.90, p = 0.11).

CONCLUSIONS

Our meta-analysis confirmed that ACE I/D polymorphism was associated with pneumonia risk. However, ACE I/D polymorphism was not associated with pneumonia mortality.

CYP1A1, GCLC, AGT, AGTR1 gene-gene interactions in community-acquired pneumonia pulmonary complications

This study was conducted to establish the possible contribution of functional gene polymorphisms in detoxification/oxidative stress and vascular remodeling pathways to community-acquired pneumonia (CAP) susceptibility in the case-control study (350 CAP patients, 432 control subjects) and to predisposition to the development of CAP complications in the prospective study. All subjects were genotyped for 16 polymorphic variants in the 14 genes of xenobiotics detoxification CYP1A1, AhR, GSTM1, GSTT1, ABCB1, redox-status SOD2, CAT, GCLC, and vascular homeostasis ACE, AGT, AGTR1, NOS3, MTHFR, VEGFα. Risk of pulmonary complications (PC) in the single locus analysis was associated with CYP1A1, GCLC and AGTR1 genes. Extra PC (toxic shock syndrome and myocarditis) were not associated with these genes. We evaluated gene-gene interactions using multi-factor dimensionality reduction, and cumulative gene risk score approaches. The final model which included >5 risk alleles in the CYP1A1 (rs2606345, rs4646903, rs1048943), GCLC, AGT, and AGTR1 genes was associated with pleuritis, empyema, acute respiratory distress syndrome, all PC and acute respiratory failure (ARF). We considered CYP1A1, GCLC, AGT, AGTR1 gene set using Set Distiller mode implemented in GeneDecks for discovering gene-set relations via the degree of sharing descriptors within a given gene set. N-acetylcysteine and oxygen were defined by Set Distiller as the best descriptors for the gene set associated in the present study with PC and ARF. Results of the study are in line with literature data and suggest that genetically determined oxidative stress exacerbation may contribute to the progression of lung inflammation.

Functional polymorphisms in the CYP1A1, ACE, and IL-6 genes contribute to susceptibility to community-acquired and nosocomial pneumonia

OBJECTIVES

To establish the contribution of genetic host factors to the risk of community-acquired pneumonia (CAP) and nosocomial pneumonia (NP) in the population of the Russian Federation.

METHODS

A total of 796 subjects (CAP: 334 patients, 134 controls; NP: 216 critically ill patients with NP, 105 critically ill patients without NP) were included in two case-control studies. We analyzed 13 polymorphisms in 11 genes (IL-6, TNF-α, MBL2, CCR5, NOS3, CYP1A1 (three sites), GSTM1, GSTT1, ABCB1, ACE, and MTHFR) using a tetra-primer allele-specific PCR method.

RESULTS

Individual single nucleotide polymorphism (SNP) analysis revealed a strong association between CYP1A1 rs2606345 and CAP (p=3.9 × 10(-5), odds ratio (OR) 0.42, 95% confidence interval (CI) 0.27-0.63). Three genes (CYP1A1, ACE, and IL-6) were identified that account for part of the increase in vulnerability to both diseases, CAP and NP. The carriage of three predisposing genotypes versus protective genotypes increased the CAP risk (p=0.001, OR 7.01, 95% CI 1.99-24.70) and NP risk (p=0.028, OR 4.34, 95% CI 1.15-16.45).

CONCLUSIONS

Genetic predisposition to CAP and NP is attributed to the cumulative contribution of polymorphisms at the CYP1A1, IL-6, and ACE genes, independently of age, gender, causative pathogen, and the use of mechanical ventilation, in patients in the Russian Federation.

Insertion/deletion polymorphism of the angiotensin-converting enzyme considerably changes postoperative outcome

STUDY OBJECTIVE

To evaluate the influence of insertion/deletion (ID) polymorphism of the angiotensin-converting enzyme (ACE) gene on clinical outcome of cardiac valve surgery.

DESIGN

Prospective, blinded observational study.

SETTING

Operating room and intensive care unit (ICU) of a university hospital.

PATIENTS

110 adult patients requiring elective cardiac valve surgery requiring cardiopulmonary bypass.

MEASUREMENTS

Patients' preoperative data (age, gender, body weight, New York Heart Association score, medication, biochemical data, and comorbid disorders), anesthetic management (blood pressure, heart rate, blood loss and transfusion, and cardiorespiratory complications and their treatment), and postoperative outcome (life-threatening complications, nosocomial infections, reintubation/reoperation, death, and duration of ICU stay and hospitalization) were recorded. ACE ID was detected by gel electrophoresis following conventional polymerase chain reaction. Patients were divided into two groups postoperatively; groups with II and non-II (ID and DD) genotypes, and group differences were analyzed.

MAIN RESULTS

Distribution of ACE ID in II, ID, and DD genotypes was 29%, 59%, and 12%, respectively. The non-II group had significantly greater postoperative blood loss and transfusion (P < 0.05), more common postoperative infections, and longer ICU stay duration than the II group (P < 0.01).

CONCLUSIONS

ACE ID polymorphism is associated with a higher incidence of postoperative complications, including postoperative infections, in patients undergoing cardiac valve surgery.

Host genetic risk factors for community-acquired pneumonia

This study was conducted to establish the contribution of genetic host factors in the susceptibility to community acquired pneumonia (CAP) in the Russian population. Patients with CAP (n=334), volunteers without a previous history of CAP, constantly exposed to infectious agents, control A group (n=141) and a second control group B consisted of healthy persons (n=314) were included in the study. All subjects were genotyped for 13 polymorphic variants in the genes of xenobiotics detoxification CYP1A1 (rs2606345, rs4646903, and rs1048943), GSTM1 (Ins/del), GSTT1 (Ins/del), ABCB1 rs1045642); immune and inflammation response IL-6 (rs1800795), TNF-a (rs1800629), MBL2 (rs7096206), CCR5 (rs333), NOS3 (rs1799983), angiotensin-converting enzyme ACE (rs4340), and occlusive vascular disease/hyperhomocysteinemia MTHFR (rs1801133). Seven polymorphic variants in genes CYP1A1, GSTM1, ABCB1, NOS3, IL6, CCR5 and ACE were associated with CAP. For two genes CYP1A1 and GSTM1 associations remained significant after correction for multiple comparisons. Multiple analysis by the number of all risk genotypes showed a highly significant association with CAP (P=2.4×10(-7), OR=3.03, 95% CI 1.98-4.64) with the threshold for three risk genotypes. Using the ROC-analysis, the AUC value for multi-locus model was estimated as 68.38.

Post-stroke pneumonia prevention by angiotensin-converting enzyme inhibitors: results of a meta-analysis of five studies in Asians

INTRODUCTION

Angiotensin-converting enzyme inhibitors (ACEIs) are reported to reduce the incidence of aspiration pneumonia in hypertensive patients. In this study, a metaanalysis was conducted to obtain statistically more reliable estimates of outcome.

METHODS

The MEDLINE and JMEDICINE databases were searched and the following study selection criteria were applied: (1) comparative controlled studies identified with the following keywords: drug therapy, ACEI, hypertension, swallowing function, dysphagia, stroke, and pneumonia; (2) a minimum follow-up period of 6 months; and (3) a minimum number of patients of more than 100. Patients with hypertension and a history of stroke or transient ischemic attack (TIA) in five controlled studies that reported the incidence of pneumonia were included in the analysis.

RESULTS

A total of 8,693 post-stroke patients were given ACEIs with another antihypertensive agent or placebo as a control. In all studies, ACEIs, particularly imidapril, exhibited preventive effects equating to a relative risk that ranged from 0.32 to 0.81 compared with controls. In the combined studies the overall relative risk of ACEI-treated patients versus controls was 0.61 (95% confidence intervals [CI] 0.51-0.75; P < 0.001). Among Asian patients, the relative risk was 0.42 (95% CI 0.32-0.56; P < 0.001). Among Japanese patients, an even greater preventive effect was found for ACEIs versus other antihypertensives (relative risk: 0.38 [95% CI 0.27-0.54; P < 0.001]).

CONCLUSION

ACEIs appear to be more effective than other antihypertensive agents or placebo in reducing pneumonia risk in post-stroke patients, especially in Asian populations.

Role of angiotensin-converting enzyme gene polymorphism in persistent pulmonary hypertension of the newborn

AIM

To evaluate the association of angiotensin-converting enzyme (ACE) gene polymorphism with risk/severity of persistent pulmonary hypertension of the newborn (PPHN) among at risk infants.

METHODS

Infants ≥ 34 weeks with respiratory distress at birth were recruited. PPHN was diagnosed clinically and by cardiac echocardiogram. Control group consisted of infants with respiratory distress who did not develop PPHN. ACE genotyping (DD, II, DI genotypes) and serum ACE levels were determined.

RESULTS

A total of 120 infants were included (PPHN = 44; control = 76). Frequency of ACE DD genotype was not different between the two groups of infants (25% versus 33%). Among PPHN infants, severity of illness did not differ between genotypes. Mean (SD) serum ACE levels [15 (9) versus 24 (13) versus 29 (14) U/L] were positively associated with the number of D alleles and inversely associated with infants' gestational age (GA) and level of cardiovascular support.

CONCLUSION

Angiotensin-converting enzyme gene polymorphism did not impact the risk or severity of PPHN among infants ≥ 34 weeks GA.

Risk factors for aspiration pneumonia in frail older people: a systematic literature review

OBJECTIVE

To systematically review the risks for aspiration pneumonia in frail older people and the contribution of bad oral health among the risk factors.

DESIGN

Systematic literature review.

SETTING

PubMed (Medline), Web of Science, Cochrane Library, EMBASE, and CINAHL were searched for eligible studies, published in English in the period January 2000 to April 2009.

PARTICIPANTS

Frail older people.

MEASUREMENTS

Only publications with regard to hospitalized, institutionalized, or frail home-dwelling people of 60 years and older were eligible. Two authors independently assessed the publications for their methodological quality. Unadjusted and adjusted odds ratios and their corresponding 95% confidence intervals for respective risk factors related to aspiration pneumonia were extracted. The results were evaluated according to the levels of evidence of the Oxford Centre for Evidence-based Medicine.

RESULTS

A total of 21 publications fulfilled the quality criteria. Evidence level 2a (systematic review with homogeneity of cohort studies) was found for a positive relationship between aspiration pneumonia and age, male gender, lung diseases, dysphagia, and diabetes mellitus; 2b (individual cohort study) for severe dementia, angiotensin I-converting enzyme deletion/deletion genotype, and bad oral health; 3a (systematic review with homogeneity of case-control studies) for malnutrition; 3b (individual case-control study) for Parkinson's disease and the use of antipsychotic drugs, proton pump inhibitors, and angiotensin-converting enzyme inhibitors. The contribution of bad oral health among the risk factors seems limited.

CONCLUSION

Thirteen significant risk factors were identified: age, male gender, lung diseases, dysphagia, diabetes mellitus, severe dementia, angiotensin I-converting enzyme deletion/deletion genotype, bad oral health, malnutrition, Parkinson's disease, and the use of antipsychotic drugs, proton pump inhibitors, and angiotensin-converting enzyme inhibitors. The contribution of bad oral health seems limited.

Association between renin-angiotensin system gene polymorphism and recurrent wheezing in Chinese children: a 4-year follow-up study

This study aimed to clarify the association between angiotensin-converting enzyme (ACE) gene polymorphisms and infant wheezing, and to determine whether an association may contribute to early prediction of persistent wheezing and asthma. The study cohort comprised 149 patients with asthma, 169 patients with wheezing but no clinical diagnosis of asthma and 165 healthy control subjects. The insertion/deletion (I/D) polymorphism of the ACE gene was determined by polymerase chain reaction. Total serum immunoglobulin E was determined for the wheezy group and a 4-year follow-up study was carried out to observe wheezing relapse. Significant differences were found between patients and controls in allele frequency and genotype distribution. The DD genotype was more frequent in patients in the wheezing and asthma groups than in the control subjects. Patients with the DD genotype had a higher frequency of relapse than patients expressing the ID or II genotypes. It is concluded that the DD genotype of ACE is a risk factor for recurrent wheezing in early childhood.

Role of angiotensin-converting enzyme gene polymorphisms in children with sepsis and septic shock

BACKGROUND

Sepsis is characterized by a systemic inflammatory response. Its development and outcome are associated with host defense, pathogenicity of the microorganism and genetic polymorphisms. Genetic polymorphisms of the immune system genes have been shown to have a close relationship with the clinical outcomes of sepsis. Angiotensin-converting enzyme (ACE) plays a major role in the host defense against invading pathogens. It is therefore likely that polymorphisms in the ACE gene may have an important effect on determining the development and the outcome of sepsis.

METHODS

Ninety-eight children diagnosed as having sepsis and 287 healthy children were included in the study. Insertion/deletion polymorphisms were analyzed using reverse-hybridization assay.

RESULTS

The carriers of I allele (D/I genotype and I/I genotype) were found to have an increased risk of developing sepsis compared to the controls.

CONCLUSION

DD genotype may play a positive role against the development of sepsis in healthy children.

Angiotensin-converting enzyme insertion/deletion polymorphism and risk and outcome of pneumonia

BACKGROUND

Recent studies have suggested involvement of the angiotensin-converting enzyme (ACE) insertion/deletion (I/D) polymorphism in the susceptibility to and severity of community-acquired pneumonia (CAP) in Asian populations. We have explored the hypothesis that the ACE I/D polymorphism affects the risk and outcome of CAP in a Dutch white population.

METHODS

This is a hospital-based prospective observational study including patients with CAP admitted between October 2004 and August 2006. All patients were genotyped, and pneumonia severity and clinical outcome were compared between patients with II, ID, and DD genotypes of the ACE gene. Pneumonia severity was assessed on day of hospital admission and consecutively on days 2, 3, 5, and 10 of hospital stay using the acute physiology score (APS). Outcomes evaluated were duration of hospital stay, ICU admittance, and in-hospital and 28-day mortality rates. To study the association between ACE genotype and risk of pneumonia, the distribution of the ACE I/D polymorphism was compared with healthy control subjects from the same geographic region.

RESULTS

In total, 200 patients with pneumonia and 200 control subjects were included in the study. Mean age of the patients was 63 years. APS scores were not different between the genotype groups on any of the days, and all clinical outcomes (duration of hospital stay, ICU admittance, in-hospital and 28-day mortality rates) were comparable between the three genotype groups. The ACE I/D genotype distribution was identical for patients and control subjects (p = 0.973).

CONCLUSIONS

The ACE I/D polymorphism is not associated with risk and outcome of CAP in the Dutch white population.

Genetic Basis of Physical Fitness

Environmental stimuli interact with common genetic variants to determine individual characteristics including physical performance: ∼80% of variation in arm eccentric flexor strength and grip strength may be genetically determined. However, many physical characteristics and physiological processes determine physical performance, and each is regulated by a large number of genes: strong genetic influences on maximum exertional oxygen uptake, heart size, lean mass, skeletal muscle growth, and bone mineral density have all been described. To date few variants strongly influencing global performance have been identified. One such is the presence (Insertion, I allele) rather than absence (Deletion, D allele) of a DNA segment in the gene encoding angiotensin-converting enzyme (ACE): The I allele has been associated with fatigue resistance/endurance, and the D-allele with strength gain.

Angiotensin‐Converting Enzyme Inhibition—Emerging Pulmonary Issues Relating to Cough

Angiotensin-converting enzyme (ACE) inhibitors are viewed by many as important treatment options for both the management of hypertension and the provision of end-organ protection. ACE inhibitors have not been looked on as having any clearly recognizable direct pulmonary benefits; rather, their pulmonary effects have been felt to be a nuisance by virtue of their association with cough. ACE inhibitor-related cough is well characterized. What is less well appreciated is the relationship between sleep apnea, pneumonia, and ACE inhibitor-related cough. These new pulmonary observations in patients afflicted with an ACE inhibitor-related cough should revive interest in this bothersome side effect.

Systemic inhibition of the angiotensin-converting enzyme limits lipopolysaccharide-induced lung neutrophil recruitment through both bradykinin and angiotensin II-regulated pathways

Recruitment of neutrophils to the lung is a sentinel event in acute lung inflammation. Identifying mechanisms that regulate neutrophil recruitment to the lung may result in strategies to limit lung damage and improve clinical outcomes. Recently, the renin angiotensin system (RAS) has been shown to regulate neutrophil influx in acute inflammatory models of cardiac, neurologic, and gastrointestinal disease. As a role for the RAS in LPS-induced acute lung inflammation has not been described, we undertook this study to examine the possibility that the RAS regulates neutrophil recruitment to the lung after LPS exposure. Pretreatment of mice with the angiotensin-converting enzyme (ACE) inhibitor enalapril, but not the anti-hypertensive hydralazine, decreased pulmonary neutrophil recruitment after exposure to LPS. We hypothesize that inhibition of LPS-induced neutrophil accumulation to the lung with enalapril occurred through both an increase in bradykinin, and a decrease in angiotensin II (ATII), mediated signaling. Bradykinin receptor blockade reversed the inhibitory effect of enalapril on neutrophil recruitment. Similarly, pretreatment with bradykinin receptor agonists inhibited IL-8-induced neutrophil chemotaxis and LPS-induced neutrophil recruitment to the lung. Inhibition of ATII-mediated signaling, with the ATII receptor 1a inhibitor losartan, decreased LPS-induced pulmonary neutrophil recruitment, and this was suggested to occur through decreased PAI-1 levels. LPS-induced PAI-1 levels were diminished in animals pretreated with losartan and in those deficient for the ATII receptor 1a. Taken together, these results suggest that ACE regulates LPS-induced pulmonary neutrophil recruitment via modulation of both bradykinin- and ATII-mediated pathways, each regulating neutrophil recruitment by separate, but distinct, mechanisms.

Polymorphism of the angiotensin-converting enzyme gene affects the outcome of acute respiratory distress syndrome

OBJECTIVE

There has been increasing evidence that angiotensin II may play an important role in the pathogenesis and in the evolution of acute lung injury. It was therefore hypothesized that polymorphisms of the angiotensin-converting enzyme gene affects the risk and outcome of acute respiratory distress syndrome (ARDS).

DESIGN

Prospective, observational study.

PATIENTS AND SETTINGS

The ARDS group consisted of 101 patients treated at the medical intensive care unit; the control groups consisted of 138 "at-risk" patients treated at the medical intensive care unit due to acute respiratory failure but did not meet the ARDS criteria throughout the hospital course, and 210 non-at-risk subjects.

INTERVENTION

None.

MEASUREMENTS AND MAIN RESULTS

The ARDS patients and control subjects were genotyped for the insertion/deletion (I/D) polymorphism of the angiotensin-converting enzyme gene. Association of the polymorphism and the risk and the outcome of ARDS was analyzed. There was no significant difference in the frequencies of the genotypes between the ARDS, at-risk, and non-at-risk groups. The 28-day mortality rates were significantly different between the three angiotensin-converting enzyme genotypes (42%, 65%, and 75% for II, ID, and DD, respectively; p = .036). Survival analysis showed that the II genotype favorably affected 28-day survival (hazard ratio, 0.46; 95% confidence interval, 0.26-0.81; p = .007), whereas ARDS caused by hospital-acquired pneumonia had a negative effect (hazard ratio, 2.34; 95% confidence interval, 1.25-4.40; p = .008). The II genotype (hazard ratio, 0.53; 95% confidence interval, 0.32-0.87; p = .012) and ARDS caused by hospital-acquired pneumonia (hazard ratio, 2.13; 95% confidence interval, 1.24-3.68; p = .006) were also significant prognostic factors for the in-hospital mortality.

CONCLUSIONS

The angiotensin-converting enzyme I/D polymorphism is a significant prognostic factor for the outcome of ARDS. Patients with the II genotype have a significantly better chance of survival. This study did not show an increased risk for ARDS in Chinese patients with the D allele.

Angiotensin-converting enzyme 2 in lung diseases

The renin-angiotensin system (RAS) plays a key role in maintaining blood pressure homeostasis, as well as fluid and salt balance. Angiotensin II, a key effector peptide of the system, causes vasoconstriction and exerts multiple biological functions. Angiotensin-converting enzyme (ACE) plays a central role in generating angiotensin II from angiotensin I, and capillary blood vessels in the lung are one of the major sites of ACE expression and angiotensin II production in the human body. The RAS has been implicated in the pathogenesis of pulmonary hypertension and pulmonary fibrosis, both commonly seen in chronic lung diseases such as chronic obstructive lung disease. Recent studies indicate that the RAS also plays a critical role in acute lung diseases, especially acute respiratory distress syndrome (ARDS). ACE2, a close homologue of ACE, functions as a negative regulator of the angiotensin system and was identified as a key receptor for SARS (severe acute respiratory syndrome) coronavirus infections. In the lung, ACE2 protects against acute lung injury in several animal models of ARDS. Thus, the RAS appears to play a critical role in the pathogenesis of acute lung injury. Indeed, increasing ACE2 activity might be a novel approach for the treatment of acute lung failure in several diseases.

Tilting-Induced Decrease in Systolic Blood Pressure in Bedridden Hypertensive Elderly Inpatients: Effects of Azelnidipine

The object of this study was to examine blood pressure (BP) variability due to postural change in elderly hypertensive patients. The subjects studied were 154 elderly inpatients in a hospital for the elderly (48 male and 106 female; median age: 82 years), consisting of age- and sex-matched bedridden (n=39) and non-bedridden (n=39) normotensive controls and bedridden (n=38) and non-bedridden (n=38) hypertensive patients. BP and pulse rate (PR) were measured in the supine position, then again after a 2-min, 45 deg head-up tilt with the legs horizontal. The decrease in systolic BP (SBP) on tilting in the bedridden hypertensive group (median: -10 mmHg; range: -32 to 9 mmHg) was significantly (p<0.008) greater than those in the other three groups. Monotherapy with azeinidipine, a long-acting calcium channel blocker, for 3 months not only significantly reduced the basal BP and PR of hypertensive patients in the two groups, but also significantly (p<0.05) attenuated the tilt-induced decrease in the SBP to -3 mmHg (-19 to 25 mmHg) and enhanced the change in PR from -1 bpm (-10 to 7 bpm) to 1 bpm (-4 to 23 bpm) in the bedridden hypertensive group. Our findings indicate that tilt-induced decrease in SBP is a rather common phenomenon in bedridden elderly hypertensive patients, and that treatment with azelnidipine attenuates tilt-induced decrease in SBP, probably through an improvement of baroreceptor sensitivity.

Genetic association studies in cardiology

The last decade has witnessed the emergence of the genetic association study into the mainstream clinical literature. Technological advances and the Human Genome Project have resulted in widespread interest in exploring these new variables in clinical disease. Although the concept of relating genetic variation to disease is exciting, this excitement must be tempered by the many limitations of such analyses. Here we offer a perspective piece on genetic association studies in cardiology. We begin with a fundamental research and clinical interest-linking genes with disease. We then concentrate the body of the article on the statistical aspects of these studies that are often overlooked or underemphasized. We then use specific examples from the literature to illustrate some of our statistical considerations. We then focus on the distinction between association and causation and conclude with perspectives on how this field of study may move forward in a productive manner.

Angiotensin converting enzyme insertion/deletion polymorphism does not alter sepsis outcome in ventilated very low birth weight infants

OBJECTIVE

This study compared the effect of the angiotensin-converting enzyme (ACE) insertion/deletion (I/D) polymorphisms on the incidence and outcome of sepsis in ventilated very low birth weight infants.

STUDY DESIGN

Infectious complications were retrospectively determined in 295 (234 African-American, 58 Caucasian and three Hispanic) mechanically ventilated very low birth weight (VLBW) infants (<1500 g at birth) and compared ACE I/D genotype.

RESULTS

The incidence of the D allele in the study population was 0.60. A total of 113 (38.3%) infants were homozygous DD, 128 (43.4%) were heterozygous ID and 54 (18.3%) were homozygous II. One or more episodes of late BSI developed in 28 (52%) of 54 infants with the II genotype, 66 (52%) of 128 infants with the ID genotype and 52 (46%) of 113 infants with the DD genotype (p=0.618). Neither the rates of non-CONS BSI (II: 24%, ID: 23%, DD: 22%; p=0.937) nor multiple bacteremic/fungemic episodes (II: 13%, ID: 16%, DD: 12%; p=0.641) were different between genotype groups. The ACE I/D polymorphism had no effect on sepsis-related mortality (II: 7%, ID: 5%, DD: 4%; p=0.692). Sepsis mortality for infants with late BSI was 14% in infants with the II genotype, 9% with the ID genotype and 10% with the DD genotype (p=0.764).

CONCLUSIONS

The ACE I/D polymorphism does not have a significant effect on the incidence or outcome of sepsis in ventilated VLBW infants.

Community-acquired pneumonia: pathophysiology and host factors with focus on possible new approaches to management of lower respiratory tract infections

The present understanding of the pathophysiology of community-acquired pneumonia (CAP) explains the mechanism for many specific manifestations, but does not address adequately why only some patients experience complications. Recent advances in under-standing the genetics of complex illnesses offer hope for a more complete insight into the pathogenesis of CAP. This article reviews genetic variation in the molecules involved in the known patho-genic mechanisms of CAP, including cough, bacterial recognition, inflammation and the compensatory anti-inflammatory response,and organ dysfunction.

Effects of an Angiotensin-converting Enzyme Inhibitor–based Regimen on Pneumonia Risk

Observational studies conducted among Asian populations suggest that the risk of pneumonia is substantially reduced among users of angiotensin-converting enzyme (ACE) inhibitors but not other blood pressure-lowering agents. We conducted analyses of the effects of ACE inhibitor therapy on pneumonia in 6,105 patients with a history of stroke or transient ischemic attack enrolled in a randomized trial conducted in Australasia, Europe, and Asia. Patients were randomly assigned perindopril-based active treatment or placebo. The effects of ACE inhibitors on pneumonia (fatal or nonfatal) were determined from Cox models fitted according to the principle of intention to treat. During a median follow-up of 3.9 years, 261 patients developed pneumonia. Overall, active treatment was associated with a nonsignificant 19% lower risk of pneumonia (95% confidence interval, -3 to 37; p = 0.09) compared with placebo. Active treatment significantly reduced the risk of pneumonia among participants of Asian ethnicity (47%, 14-67%; p = 0.01), with no significant effect among non-Asian participants (5%, -27 to 29%; p = 0.7) (p for homogeneity = 0.04). These findings substantially add to the body of evidence about the effects of these drugs on pneumonia but do not provide the definitive information required to inform clinical decisions about the prevention of pneumonia with ACE inhibitors.

[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.

Genetics of sepsis and pneumonia

PURPOSE OF REVIEW

The genetic risk for pneumonia, sepsis, and other serious infections is generally unrecognized or underestimated. Although the strongest evidence for a genetic risk comes from an adoptee study, most evidence for a genetic role in infection involves association studies, which compare the incidence of specific mutations in a population with infection to a control population. Recent association studies in pneumonia and sepsis will be reviewed.

RECENT FINDINGS

Most positive association studies examine genes for important inflammatory molecules such as tumor necrosis factor, the interleukin-1 family, interleukin-10, and angiotensin converting enzyme, as well as molecules important in antigen recognition, such as the mannose-binding lectin, CD-14, and toll-like receptors.

SUMMARY

A genetic component to risk of sepsis and resultant complications clearly exists. Confirmation of the findings in this review and associations with other genetic polymorphisms await large-scale population studies and further validation of the physiologic significance of the variant alleles.

Salt sensitivity of Japanese from the viewpoint of gene polymorphism

Excess salt intake is an important environmental risk for the predisposition to essential hypertension. Previous physiological studies have shown that salt sensitivity is associated with insulin resistance, enhancement of sympathetic nerve activity and decrease of blood pressure decline at night. We have been examining the genetic importance of candidate gene polymorphisms of salt-sensitive hypertension using several populations. The angiotensinogen gene (AGT) is a thrifty gene which increases the risk for common disease with growth of civilization via sodium and body fluid retention. The CC genotype of the AGT/T+31C polymorphism, which is in complete linkage disequilibrium with the TT genotype of the M235T polymorphism, was associated with a decrease of blood pressure decline at night in the Ohasama Study. On the other hand, the Gly460Trp genotype of the alpha-adducin gene (ADD1) is associated with erythrocyte sodium transport and increases tubular sodium reabsorption and risk for hypertension. We also revealed in the Ohasama Study that the Trp460 allele of ADD1 is associated with hypertension in young subjects with low renin activity. In addition to these polymorphisms, the T(-344)C polymorphism in the promoter of the aldosterone synthase gene (CYP11B2) and the C825T polymorphism of the G-protein beta3 subunit gene (GNB3) are considered candidates for the genetic risk of salt-sensitive hypertension. We compared the allele frequency of five candidate genes between Japanese and Caucasians; the results showed that the frequencies of all alleles were significantly higher in Japanese than in Caucasians. This interesting finding might suggest a feasible explanation for the huge interracial differences in the frequency of salt-sensitive hypertension.