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

Evolution of multiple omics approaches to define pathophysiology of pediatric acute respiratory distress syndrome

Pediatric acute respiratory distress syndrome (PARDS), though both common and deadly in critically ill children, lacks targeted therapies. The development of effective pharmacotherapies has been limited, in part, by lack of clarity about the pathobiology of pediatric ARDS. Epithelial lung injury, vascular endothelial activation, and systemic immune activation are putative drivers of this complex disease process. Prior studies have used either hypothesis-driven (e.g., candidate genes and proteins, in vitro investigations) or unbiased (e.g., genome-wide association, transcriptomic, metabolomic) approaches to predict clinical outcomes and to define subphenotypes. Advances in multiple omics technologies, including genomics, transcriptomics, proteomics, and metabolomics, have permitted more comprehensive investigation of PARDS pathobiology. However, omics studies have been limited in children compared to adults, and analyses across multiple tissue types are lacking. Here, we synthesized existing literature on the molecular mechanism of PARDS, summarized our interrogation of publicly available genomic databases to determine the association of candidate genes with PARDS phenotypes across multiple tissues and cell types, and integrated recent studies that used single-cell RNA sequencing (scRNA-seq). We conclude that novel profiling methods such as scRNA-seq, which permits more comprehensive, unbiased evaluation of pathophysiological mechanisms across tissue and cell types, should be employed to investigate the molecular mechanisms of PRDS toward the goal of identifying targeted therapies.

Ethnic and age-specific acute lung injury/acute respiratory distress syndrome risk associated with angiotensin-converting enzyme insertion/deletion polymorphisms, implications for COVID-19: A meta-analysis

BACKGROUND

The reported association between an insertion/deletion (I/D) polymorphism in the angiotensin-converting enzyme (ACE) gene and the risk for acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) remains controversial despite the publication of four meta-analyses on this topic. Here, we updated the meta-analysis with more studies and additional assessments that include adults and children within the context of the coronavirus disease 2019 (COVID-19) pandemic.

METHODS

Sixteen articles (22 studies) were included. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using three genetic models (allele, recessive and dominant), in which ARDS patients were compared with non-ARDS patients (A1) and healthy controls (A2). Mortality outcomes were also assessed (A3). The influence of covariates was examined by meta-regression. Bonferroni correction was performed for multiple pooled associations. Subgroup analyses based on ethnicity (Asians, Caucasians) and life stage (adults, children) were conducted. Heterogeneity was addressed with outlier treatment.

RESULTS

This meta-analysis generated 68 comparisons, 21 of which were significant. Of the 21, four A1 and three A3 highly significant (Pa = 0.00001-0.0008) outcomes withstood Bonferroni correction. For A1, allele and recessive associations were found in overall (OR 0.49, 95% CI 0.39-0.61), Caucasians (OR 0.46, 95% CI 0.35-0.61) and children (ORs 0.49-0.66, 95% CI 0.33-0.84) analyses. For A3, associations were found in overall (dominant: OR 0.45, 95% CI 0.29-0.68) and Asian subgroup (allele/ dominant: ORs 0.31-0.39, 95% CIs 0.18-0.63) analyses. These outcomes were either robust, or statistically powered or both and uninfluenced by covariates.

CONCLUSIONS

Significant associations of the ACE I/D polymorphism with the risk of ALI/ARDS were indicated in Caucasians and children as well as in Asians in mortality analysis. These findings were underpinned by high significance, high statistical power and robustness. ACE genotypes may be useful for ALI/ARDS therapy for patients with COVID-19.

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.

Double-blind, placebo-controlled pilot randomized trial of methylprednisolone infusion in pediatric acute respiratory distress syndrome

OBJECTIVE

Low-dose methylprednisolone therapy in adults with early acute respiratory distress syndrome reduces systemic inflammation, duration of mechanical ventilation, and ICU length of stay. We report a pilot randomized trial of glucocorticoid treatment in early pediatric acute respiratory distress syndrome.

DESIGN

Double-blind, placebo-controlled randomized clinical trial.

SETTING

Le Bonheur Children's Hospital, Memphis, TN.

PATIENTS

Children (0-18 yr) with acute respiratory distress syndrome undergoing mechanical ventilation.

INTERVENTIONS

Patients were randomly assigned to steroid or placebo groups within 72 hours of intubation. IV methylprednisolone administered as loading dose (2 mg/kg) and continuous infusions (1 mg/kg/d) on days 1-7 and then tapered over days 8-14. Both groups were ventilated according to the Acute Respiratory Distress Syndrome Network protocol modified for children. Daily surveillance was performed for adverse effects.

MEASUREMENTS AND MAIN RESULTS

Thirty-five patients were randomized to the steroid (n = 17, no death) and placebo groups (n = 18, two deaths). No differences occurred in length of mechanical ventilation, ICU stay, hospital stay, or mortality between the two groups. At baseline, higher plateau pressures (p = 0.006) and lower Pediatric Logistic Organ Dysfunction scores (p = 0.04) occurred in the steroid group; other characteristics were similar. Despite higher plateau pressures on days 1 (p = 0.006) and 2 (p = 0.025) due to poorer lung compliance in the steroid group, they had lower PaCO2 values on days 2 (p = 0.009) and 3 (p = 0.014), higher pH values on day 2 (p = 0.018), and higher PaO2/FIO2 ratios on days 8 (p = 0.047) and 9 (p = 0.002) compared with the placebo group. Fewer patients in the steroid group required treatment for postextubation stridor (p = 0.04) or supplemental oxygen at ICU transfer (p = 0.012). Steroid therapy was not associated with detectable adverse effects.

CONCLUSION

This study demonstrates the feasibility of administering low-dose glucocorticoid therapy and measuring clinically relevant outcomes in pediatric acute respiratory distress syndrome. Changes in oxygenation and/or ventilation are consistent with early acute respiratory distress syndrome pathophysiology and results of similar clinical trials in adults. We propose and design a larger randomized trial to define the role of glucocorticoid therapy in pediatric acute respiratory distress syndrome.

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 is associated with severe hypoxemia in pediatric ARDS

PURPOSE

The D allele of the insertion/deletion (I/D) polymorphism of a 287-bp sequence in the angiotensin-converting enzyme (ACE) gene has been associated with an increased activity of this enzyme. Its role in susceptibility to acute respiratory distress syndrome (ARDS) has not been well defined. We hypothesized that ACE I/D genotype in pediatrics is associated with ARDS and plasma levels of angiotensin II.

METHODS

Prospective case-control study in patients under 15 years of age from a mixed Chilean population. Sixty patients with ARDS and 60 controls were included. Association between ACE genotype and ARDS was evaluated as the primary outcome; mortality and severe hypoxemia were examined as secondary outcomes. Plasma angiotensin-II concentration was measured by immunoassay at admission.

RESULTS

Frequency of ACE I/D genotype was similar in ARDS and control groups (p = 0.18). In the ARDS group, severe hypoxemia was less frequent in D allele carriers (p < 0.05). Plasma angiotensin-II levels were associated with genotype in the ARDS group, but not controls, being higher in D allele carriers (p = 0.016).

CONCLUSION

These data do not support the association between ACE I/D genotype and ARDS, although severe hypoxemia was less frequent in D allele carriers. ACE I/D polymorphism modified angiotensin-II levels in pediatric ARDS, but its pathogenic role is not well understood and needs to be addressed in future studies.

Genetic variability in complement activation modulates the systemic inflammatory response syndrome in children

OBJECTIVE

To determine the impact of genetic variability in complement activation on early development of the systemic inflammatory response syndrome (SIRS) in general pediatric critical care.

DESIGN

Prospective, observational, cohort study.

SETTING

A tertiary pediatric intensive care unit in the United Kingdom.

PATIENTS

Children with at least one organ failure expected to stay in the intensive care unit >12 hrs, or an expected death within 12 hrs.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

A total of 299 children were genotyped for functional polymorphisms in the complement activation cascade. We identified complement factor H as an important independent genetic modifier of SIRS/sepsis. Homozygosity for the complement factor H Y402H polymorphism, which is thought to reduce complement inhibition, was associated with less frequent SIRS/sepsis (the adjusted odds ratio for the homozygous variant complement factor H Y402H [CC] carriers was 0.3, 95% confidence interval, 0.1-0.7, p = .005). We also confirmed that structural and promoter variant mannose-binding lectin genotypes are a risk factor for SIRS/sepsis in pediatric critical care (adjusted odds ratio, 2.5; 95% confidence interval, 1.3-5.0, p = .008). Both findings were independent of clinical characteristics and other potentially confounding genetic polymorphisms in the innate immune system.

CONCLUSIONS

Functional polymorphisms in the complement activation cascade modify the risk for early SIRS/sepsis in general pediatric critical care. The complement factor H Y402H variant allele is protective, whereas the mannose-binding lectin variant polymorphisms increase risk. A genotype that permits vigorous complement activation to an infectious or inflammatory insult may offer protection from development of systemic inflammation.