Genetics of community-acquired pneumonia

rs1840680 single nucleotide polymorphism in Pentraxin 3: a potential protective biomarker of severe community-acquired pneumonia

Objective

Single nucleotide polymorphisms (SNPs) of pentraxin 3 (PTX3) are associated with various outcomes of lung infections. This study aimed to analyze the relationship between PTX3 polymorphisms and the severity of community-acquired pneumonia (CAP).

Methods

This is a retrospective case-control study comprising 43 patients with severe CAP (SCAP) and 97 patients with non-severe CAP. Three SNPs in the PTX3 gene (rs2305619, rs3816527, and rs1840680) from peripheral blood samples were genotyped by real-time polymerase chain reaction. The association between each SNP and the CAP severity was analyzed by logistic regression analysis.

Results

We found that the rs1840680 polymorphism was significantly associated with CAP clinical severity. However, no such association was observed for the genotypes and allele frequencies of rs2305619 or rs3816527. The PTX3 rs1840680 AG genotype was an independent factor for a lower risk of SCAP after multivariate logistic regression analysis. Male sex and coronary heart disease were associated with an increased risk of SCAP.

Conclusions

The PTX3 rs1840680 AG genotype was found to be associated with a lower risk of SCAP, and may serve as a potential protective biomarker to help clinical judgment and management.

Genetic variants of interferon regulatory factor 5 associated with the risk of community-acquired pneumonia

Interferon regulatory factor 5 (IRF5) is a key transcription factor involved in the control of the expression of pro-inflammatory cytokines and immune responses to infection, and multiple polymorphisms of the IFR5 gene have been shown to be associated with autoimmune and infectious diseases. Several studies have investigated single nucleotide polymorphisms (SNPs) in a number of genes associated with the susceptibility to or severity and outcome of community-acquired pneumonia (CAP), but no research has yet been conducted on the role of IRF5 gene polymorphisms in CAP. In this study, we investigated the effects of four IFR5 variants, rs77571059, rs2004640, rs10954213, and rs3807306 on the susceptibility to CAP by genotyping 228 CAP patients and 177 healthy donors. Our results indicated that IFR5 variants rs77571059 and rs2004640 and haplotype GTAA were associated with the susceptibility to CAP and rs77571059 was related to the severity of the disease, suggesting that IFR5 variants may contribute to the pathogenesis of CAP and may serve as prognostic markers of CAP susceptibility and outcome.

Community-acquired pneumonia

Community-acquired pneumonia causes great mortality and morbidity and high costs worldwide. Empirical selection of antibiotic treatment is the cornerstone of management of patients with pneumonia. To reduce the misuse of antibiotics, antibiotic resistance, and side-effects, an empirical, effective, and individualised antibiotic treatment is needed. Follow-up after the start of antibiotic treatment is also important, and management should include early shifts to oral antibiotics, stewardship according to the microbiological results, and short-duration antibiotic treatment that accounts for the clinical stability criteria. New approaches for fast clinical (lung ultrasound) and microbiological (molecular biology) diagnoses are promising. Community-acquired pneumonia is associated with early and late mortality and increased rates of cardiovascular events. Studies are needed that focus on the long-term management of pneumonia.

Associations of three well-characterized polymorphisms in the IL-6 and IL-10 genes with pneumonia: a meta-analysis

Published data on the associations between three well-characterized polymorphisms in the interleukin 6 and 10 (IL-6 and IL-10) genes and the risk of pneumonia are inconclusive. A meta-analysis was performed to derive a more precise estimate. The electronic databases MEDLINE (Ovid) and PubMed were searched from the earliest possible year to May 2014. A total of 9 articles met the criteria, and these included 3460 patients with pneumonia and 3037 controls. The data were analyzed with RevMan software, and risk estimates are expressed as odds ratios (ORs) and 95% confidence intervals (95% CIs). Analyses of the full data set failed to identify any significant association of pneumonia risk with the IL-6 gene -174C allele (OR = 1.00; 95% CI: 0.98–1.03), the IL-10 gene -592C allele (OR = 1.20; 95% CI: 0.95–1.52), or the IL-10 gene -1082A allele (OR = 1.21; 95% CI: 0.99–1.49). In a subgroup analysis by pneumonia type, ethnicity, sample size and quality score, no significantly increased risk of pneumonia was found for individuals carrying the IL-6 gene -174C allele. There was a low probability of publication bias, as reflected by the fail-safe number. This meta-analysis suggests that there is no significantly increased risk of pneumonia associated with previously reported IL-6 and IL-10 polymorphisms.

IL6-174 G/C gene polymorphism and its relation to serum IL6 in Egyptian children with community-acquired pneumonia

Cytokines are involved in the pathogenesis of community acquired pneumonia (CAP). The aim of this study is to investigate the association of IL6-174 G/C gene polymorphism with CAP in Egyptian children, to assess its effect on CAP outcome and to determine its effect on the serum IL6 levels in these children. IL6-174 G/C gene polymorphism was genotyped in 210 Egyptian children (100 patients with CAP and 110 healthy controls) using PCR-RFLP, while the serum IL6 levels were measured by ELISA method. We found a significant association between the GG genotype, G allele of IL6-174 G/C SNP and susceptibility to CAP (P=0.02, 0.01 respectively). However, GG genotype and G allele were protective against severe sepsis (p=0.004), acute respiratory failure (p<0.001) and hospital mortality (p<0.001). Serum IL6 levels were significantly increased in these children while there was no relation between GG genotype and serum IL6. In conclusion, IL6-174 G/C gene polymorphism may contribute to susceptibility to CAP in Egyptian children.

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.

The role of biomarkers in community-acquired pneumonia: predicting mortality and response to adjunctive therapy

Patients with community-acquired pneumonia (CAP) in the hospital setting exhibit markedly abnormal levels of various biomarkers of infection, inflammation and coagulation. CAP is a well characterized disease, relatively homogeneous and amenable to management according to defined protocols. Hence, this group of patients represents an opportunity to investigate further these biomarkers as a means of determining disease severity and identifying candidates for new therapies. Changes in biomarker levels during the course of disease may enable physicians to identify those patients who are most at risk for deterioration and progression toward severe CAP and who are in greatest need of early intervention. Subgroup analysis of the placebo-controlled OPTIMIST trial of tifacogin in severe sepsis revealed a trend toward benefit in patients with procalcitonin levels of 2 ng/ml or greater and in those with high baseline markers of activated coagulation. Biomarker studies are being undertaken as part of the ongoing CAPTIVATE study. This study includes patients with severe CAP and will compare the efficacy and safety of recombinant tissue factor pathway inhibitor (tifacogin) versus placebo. In the future it may also be possible to use genomic markers to identify patients at greatest risk for deterioration or complications.

Interleukin-1 receptor antagonist intron 2 variable number of tandem repeats polymorphism and respiratory failure in children with community-acquired pneumonia

OBJECTIVE

To determine whether the variable nucleotide tandem repeat polymorphism in intron 2 of the interleukin-1 receptor antagonist gene is associated with lung injury in children with community-acquired pneumonia.

DESIGN

A prospective cohort of children diagnosed with community-acquired pneumonia.

SETTING

Two pediatric hospitals.

PATIENTS

Eight hundred fifty pediatric patients with community-acquired pneumonia were enrolled.

INTERVENTIONS

Genotyping of the variable nucleotide tandem repeat polymorphism in intron 2 of the interleukin-1 receptor antagonist gene was performed on DNA isolated from whole blood.

MEASUREMENTS AND MAIN RESULTS

The requirement for positive pressure ventilation or the diagnosis of acute lung injury or acute respiratory distress syndrome were the main outcomes of the study. Children (14 days-19 yrs) with community-acquired pneumonia (850) were enrolled; analysis was limited to African American (515) and Caucasian (232) patients. Of the 82 patients requiring positive pressure ventilation, 44 were diagnosed with acute lung injury or acute respiratory distress syndrome. Multivariate logistic regression analyses indicated that children without a copy of the A1 allele of the variable nucleotide tandem repeat polymorphism in intron 2 of the interleukin-1 receptor antagonist gene were more likely to need positive pressure ventilation compared to those with one or two copies of this allele (odds ratio = 2.65, confidence interval, 1.02-6.90). In addition, the absence of the A1 allele also appeared to be associated with the development of community-acquired pneumonia-induced acute lung injury/acute respiratory distress syndrome (odds ratio = 3.1, confidence interval, 0.99-9.67).

CONCLUSIONS

In children with community-acquired pneumonia, absence of the A1 allele at the interleukin-1 receptor antagonist intron 2 polymorphic site is associated with increased risk for more severe lung injury, as measured by the need for positive pressure ventilation or the development of acute lung injury or acute respiratory distress syndrome. Conversely, presence of the A1 allele is associated with decreased risk for more severe lung injury in this patient population.