Association of TLR4 polymorphisms with symptomatic respiratory syncytial virus infection in high-risk infants and young children

Respiratory syncytial virus (RSV) is a leading cause of infant mortality worldwide. Although anti-RSV Ab prophylaxis has greatly reduced infant mortality in the United States, there is currently no vaccine or effective antiviral therapy. RSV fusion (F) protein activates cells through TLR4. Two single nucleotide polymorphisms (SNPs) encoding Asp299Gly and Thr399Ile substitutions in the TLR4 ectodomain were previously associated with TLR4 hyporesponsiveness and increased susceptibility to bacterial infection. Prevalence of these SNPs was analyzed in a case series of 105 DNA samples extracted from archived nasal lavage samples from high-risk infants/young children with confirmed RSV disease who participated in two seminal clinical trials for anti-RSV prophylaxis. Frequencies of TLR4 SNPs in the case series were compared with those of literature controls, healthy adults, infants, and young children who presented with symptoms of respiratory infections (but not preselected for high risk for RSV). Both SNPs were highly associated with symptomatic RSV disease in this largely premature population (p < 0.0001), with 89.5% and 87.6% of cases being heterozygous for Asp299Gly and Thr399Ile polymorphisms versus published control frequencies of 10.5% and 6.5%, respectively. The other two control groups had similarly low frequencies. Our data suggest that heterozygosity of these two extracellular TLR4 polymorphisms is highly associated with symptomatic RSV disease in high-risk infants and support a dual role for TLR4 SNPs in prematurity and increased susceptibility to RSV not revealed by analysis of either alone.     

Genetic polymorphisms of antioxidant enzymes as risk factors for oxidative stress-associated complications in preterm infants

We aimed to identify specific polymorphisms of genes encoding for superoxide dismutase (SOD) 1 (cytoplasmic Cu/ZnSOD), SOD2 (mitochondrial MnSOD), SOD3 (extracellular Cu/ZnSOD) and CAT in a cohort of preterm infants and correlate their presence to the development of respiratory distress syndrome (RDS), bronchopulmonary dysplasia (BPD), intraventricular haemorrhage (IVH) and retinopathy of prematurity (ROP). We carried out a retrospective study to evaluate the allele frequency and the genotype distribution of polymorphisms of SODs and CAT in a population of preterm neonates (n = 152) with a gestational age ≤ 28 weeks according to the presence or absence of RDS, BPD, IVH and ROP. Moreover, we evaluated through the haplotype reconstruction analysis whether combinations of the selected polymorphisms are related to the occurrence of RDS, BPD, IVH and ROP. We found that rs8192287 SOD3 polymorphism is an independent protective factor for all grade IVH, while rs4880 and rs5746136 SOD2 polymorphisms are associated with a lower gestational age (rs4880, rs5746136) and birth weight (rs4880). Haplotypes reconstruction showed that SOD1 (GG) decreased the risk of RDS, IVH and ROP; SOD2 (GT) increased the risk of BPD and decreased the risk of RDS, IVH and ROP; SOD3 (TGC) decreased the risk of BPD and IVH; and 4) CAT (CTC) decreased the risk of RDS. The rs8192287 SOD3 polymorphism is per se an independent predictor of a decreased risk of developing IVH. Different SOD2 polymorphisms are associated per se with a lower gestational age and/or birth weight, and haplotypes of SOD1, SOD3 and CAT genes may be independent protecting or risk markers for prematurity complications.     

Genetic polymorphisms of antioxidant enzymes as risk factors for oxidative stress-associated complications in preterm infants

Abstract

We aimed to identify specific polymorphisms of genes encoding for superoxide dismutase (SOD) 1 (cytoplasmic Cu/ZnSOD), SOD2 (mitochondrial MnSOD), SOD3 (extracellular Cu/ZnSOD) and CAT in a cohort of preterm infants and correlate their presence to the development of respiratory distress syndrome (RDS), bronchopulmonary dysplasia (BPD), intraventricular haemorrhage (IVH) and retinopathy of prematurity (ROP). We carried out a retrospective study to evaluate the allele frequency and the genotype distribution of polymorphisms of SODs and CAT in a population of preterm neonates (n =?152) with a gestational age ≤?28 weeks according to the presence or absence of RDS, BPD, IVH and ROP. Moreover, we evaluated through the haplotype reconstruction analysis whether combinations of the selected polymorphisms are related to the occurrence of RDS, BPD, IVH and ROP. We found that rs8192287 SOD3 polymorphism is an independent protective factor for all grade IVH, while rs4880 and rs5746136 SOD2 polymorphisms are associated with a lower gestational age (rs4880, rs5746136) and birth weight (rs4880). Haplotypes reconstruction showed that SOD1 (GG) decreased the risk of RDS, IVH and ROP; SOD2 (GT) increased the risk of BPD and decreased the risk of RDS, IVH and ROP; SOD3 (TGC) decreased the risk of BPD and IVH; and 4) CAT (CTC) decreased the risk of RDS. The rs8192287 SOD3 polymorphism is per se an independent predictor of a decreased risk of developing IVH. Different SOD2 polymorphisms are associated per se with a lower gestational age and/or birth weight, and haplotypes of SOD1, SOD3 and CAT genes may be independent protecting or risk markers for prematurity complications.     

Genetic polymorphisms of vascular endothelial growth factor and risk for retinopathy of prematurity in South of Iran

Retinopathy of prematurity (ROP) is a multifactorial disease, that cause visual impairment in premature children. The exact pathogenesis and etiology of ROP is unknown and genetic susceptibility is considered as risk factor. Vascular endothelial growth factor (VEGF) plays a major role in retinal neovascularization and subsequently retinal detachment. VEGF polymorphism is associated with proliferative ROP in some studies. We examined the possible association of the VEGF gene polymorphisms with ROP in preterm infants in south of Iran. A total of 111 preterm infants were examined by ophthalmologist and after that were genotyped. Genotyping of the VEGF +405 (rs2010963) and VEGF +936 (rs3025039) was done by the polymerase chain reaction and restriction fragment length polymorphism methods. The frequency of VEGF alleles, genotypes and haplotype distribution were compared between groups. The patients were divided in three groups: 66 to the normal group (normal fundoscopy), and 45 to the ROP group; 30 infants were not treated with Lasertherapy (Regressive group) and 15 treated with Lasertherapy. The frequency of VEGF +405 and VEGF +936 G/C genotypes as well as allele frequencies was not different between groups. No significant difference was found between ROP with treatment and ROP without lasertherapy. Our report indicate that there is no association between the carrier states of gene polymorphisms VEGF +405, VEGF +936 and progression or spontaneous regression of ROP in preterm infants in Iranian population. However, it should be considered that angiogenesis is a complex process and genetic factors in addition to environmental factors are contributed in this pathway.     

Polymorphisms in vitamin D receptor,toll-like receptor 2 and Toll-Like receptor 4 genes links with Dengue susceptibility

Host genetic factors are known to determine disease susceptibility in dengue virus infection. Therefore, in this study association of gene polymorphisms of Vitamin D Receptor [rs731236 (Taq) and rs7975232 (Apa1)], Toll-like receptor 2 [rs5743708 (Arg735Gln) and rs5743704 (Pro631His)] and Toll-like receptor 4 [rs4986790A/G(Asp299Gly13843) and rs4986791 C/T(Thr399Ile)] were studied in cases with dengue as compared to controls. Total 98 cases of confirmed dengue virus infection and 98 age, sex and geographically matched healthy controls were enrolled and their genetic polymorphisms for the above mentioned regions were studied by Sanger sequencing. Mutant genotypes CC of VDR rs731236 (Taq1) [(OR 3.808, p value =0.02, CI 1.160-12.498)], GG of VDR rs7975232 (Apa1) [(OR 3.485, p value =0.02, CI 1.162-10.45)] and heterozygous genotypes of TLR4 rs4986790 A/G Asp299Gly [OR 2.40, p value= 0.02, CI 1.12-5.14], TLR4 rs4986791 C/T Thr399Ile [OR 2.09, p value=0.02, CI 1.12-5.14] were found to be significantly more in cases with dengue virus infection as compared to the controls. Also, at these positions mutant alleles were observed in significantly higher number of cases than controls. The values for C allele at VDR rs731236 (Taq1) were OR 1.86, p value 0.009, CI 1.162-3.001; for allele G at rs7975232( Apa1) were OR 2.71, p value 0.006, CI 1.196-2.98 for allele G at TLR4s rs4986790 A/G Asp299Gly were OR 2.35, p value 0.009, CI 1.23-4.50 and for allele T at rs4986791 C/T Thr399Ile were OR 2.36, p value=0.006, CI 1.28-4.38. VDR and TLR4 but not TLR2 gene polymorphisms were found to be associated with dengue susceptibility in Indian population.     

Lack of association between TLR4 Asp299Gly and Thr399Ile polymorphisms and sepsis susceptibility: a meta-analysis

Sepsis, a condition of systemic inappropriate inflammation response to the invasion of microorganisms, results in considerable morbidity and mortality in patients. Some, but not all, epidemiological studies have suggested that Toll-like receptor 4 (TLR4) polymorphisms, Asp299Gly and Thr399Ile, may influence the risk of at-risk patients for sepsis. Our work tried to further study the association of the two common polymorphisms with sepsis susceptibility by performing a meta-analysis of previous data. Electronic searches of MEDLINE, EMBASE and Web of Science databases were performed. Original observational studies dealing with the association between polymorphisms Asp299Gly and/or Thr399Ile and sepsis risk were selected. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated with random-effects model or fixed-effects model based on the heterogeneity analysis. Seventeen studies including 2212 cases and 3880 controls were included with most subjects of Caucasian ethnicity. The odds ratio for the association of Asp299Gly polymorphism with sepsis risk was 1.22 (95% CI: 0.90-1.65, P=0.21), and the association of Thr399Ile polymorphism was 1.16 (95%CI: 0.70-1.91, P=0.57). Subgroup analysis and sensitivity analysis did not change the results. Our meta-analysis revealed that the two common TLR4 polymorphisms, Asp299Gly and Thr399Ile, have no strong association with the likelihood of sepsis in Caucasian populations. Further studies are needed to investigate the effect of genetic networks and their mutual interactions in TLR4 signaling pathway on sepsis susceptibility.     

Matrix metalloproteinase gene polymorphisms and bronchopulmonary dysplasia: identification of MMP16 as a new player in lung development

Backgound

Alveolarization requires coordinated extracellular matrix remodeling, a process in which matrix metalloproteinases (MMPs) play an important role. We postulated that polymorphisms in MMP genes might affect MMP function in preterm lungs and thus influence the risk of bronchopulmonary dysplasia (BPD).

Methods and Findings

Two hundred and eighty-four consecutive neonates with a gestational age of <28 weeks were included in this prospective study. Forty-five neonates developed BPD. Nine single-nucleotide polymorphisms (SNPs) were sought in the MMP2, MMP14 and MMP16 genes. After adjustment for birth weight and ethnic origin, the TT genotype of MMP16 C/T (rs2664352) and the GG genotype of MMP16 A/G (rs2664349) were found to protect from BPD. These genotypes were also associated with a smaller active fraction of MMP2 and with a 3-fold-lower MMP16 protein level in tracheal aspirates collected within 3 days after birth. Further evaluation of MMP16 expression during the course of normal human and rat lung development showed relatively low expression during the canalicular and saccular stages and a clear increase in both mRNA and protein levels during the alveolar stage. In two newborn rat models of arrested alveolarization the lung MMP16 mRNA level was less than 50% of normal.

Conclusions

MMP16 may be involved in the development of lung alveoli. MMP16 polymorphisms appear to influence not only the pulmonary expression and function of MMP16 but also the risk of BPD in premature infants.     

TLR4 polymorphisms mediate impaired responses to respiratory syncytial virus and lipopolysaccharide

Severe bronchiolitis following respiratory syncytial virus (RSV) infection occurs in only a small subset of infected infants and the basis for variations in disease severity is not understood. Innate immune responses to RSV are mediated by TLR-4, and the (299)Gly and (399)Ile alleles of the TLR4 gene have been linked epidemiologically with increased severity of RSV disease in children. We hypothesized that cellular immune responses to RSV mediated by these variant forms of the receptor are defective relative to responses mediated via the common form of the receptor. Human bronchial epithelial cells were transfected with TLR4 constructs encoding the common TLR4 gene sequence ((299)Asp/(399)Thr), or the (299)Gly or (399)Ile alleles, and cytokine responses to in vitro RSV challenge were analyzed in the different transfected cells. Follow-up studies compared RSV-induced responses in PBMC from children expressing these same TLR4 genotypes. Human bronchial epithelial expressing (299)Gly or (399)Ile displayed normal levels of intracellular TLR4 but failed to efficiently translocate the receptor to the cell surface. This was associated with reduced NF-kappaB signaling post-TLR4 engagement, reduced production of IFNs, IL-8, IL-10, IL-12p35, IL-18, and CCL8, and the absence of acute-phase TNF-alpha. These findings were mirrored by blunted PBMC responses to RSV in children expressing the same TLR4 variants. Compromised first-line defense against RSV at the airway-epithelial surface of children expressing these TLR4 variants may thus confer increased susceptibility to severe infections with this virus.     

TLR4 and TLR9 polymorphism: Probable role in susceptibility among the population of Bihar for Indian visceral leishmaniasis

Genetic variations in the host TLRs genes play an important role in susceptibility and/or resistance to visceral leishmaniasis by altering the host-pathogen interaction. In this study, we investigated the association between polymorphisms of TLR4 (Asp299Gly, Thr399Ile) and TLR-9 (T-1237C), with susceptibility to visceral leishmaniasis. A bi-directional PCR amplification of specific alleles technique was used to characterize the distribution of TLR4 (Asp299Gly and Thr399Ile) and TLR9 (T-1237C) polymorphisms. A total of 60 samples were randomly selected from confirmed visceral leishmaniasis patients and 24 endemic healthy volunteers. The samples were genotyped and allele frequencies were determined. We observed that TLR4 Asp299Gly and Thr399Ile genotypes were more frequent in visceral leishmaniasis patients (10% and 15% respectively) compared to controls (4.2% and 8.3% respectively). However, the differences were not significant in TLR4 Asp299Gly and Thr399Ile alleles and genotypes. In the case of TLR9, we observed the frequency of T1237C genotype was higher in visceral leishmaniasis patients (43.3%) than in healthy controls (33.3%). Statistically significant differences were observed in TLR9 T1237C alleles and genotypes. We concluded that TLR9 T1237C, but not TLR4, gene polymorphisms can be regarded as contributors to visceral leishmaniasis susceptibility among the Indian population of Bihar state.     

CARD15 and TLR4 genes polymorphisms in atopic bronchial asthma

In order to investigate whether single nucleotide polymorphisms G(+2722)C and 3020insC in CARD15 gene and Asp299Gly in TLR4 gene contribute to atopic bronchial asthma we performed a comparative analysis of alleles and genotypes frequencies of these polymorphisms in Russian patients from Moscow. DNA samples from 283 patients with atopic bronchial asthma and 227 healthy donors were genotyped. There were associations neither of G(+2722)C and 3020insC in CARD15 gene and Asp299Gly in TLR4 gene with asthma nor of markers of CARD15 gene with asthma severity. Haplotype frequency analysis of CARD15 gene polymorphisms did not reveal significant difference between groups. However, a strong association was found between Asp299Gly and asthma severity. Allele Asp of this marker showed association with mild atopic bronchial asthma and allele Gl--with moderate/severe asthma = 0.47, 95% CI [0.24-0.93] i OR = 2.12, 95% CI [1.08-4.18] respectively).     

Toll-like receptor 2 and Toll-like receptor 4 polymorphisms in invasive pneumococcal disease

BACKGROUND: Toll-like receptors (TLRs) recognize distinct pathogen-associated molecular patterns and trigger anti-microbial host defense responses. Several in vitro and in vivo studies in mice indicate that TLR2 and TLR4 are involved in the defense against Streptococcus pneumoniae. Studies have revealed associations between polymorphisms in TLRs and human diseases. The effect of polymorphisms in TLR2 and TLR4 in the human defense to S. pneumoniae has not been studied. METHODS: We genotyped 99 Caucasian patients with invasive pneumococcal disease and 178 Caucasian controls for the known R579H, P631H and R753Q polymorphisms in TLR2 and the D299G polymorphism in TLR4 with PCR-RFLP methods. RESULTS: The distribution of the TLR2 R579H, P631H and R753Q and TLR4 D299G variants was not significantly different between the patients and the controls. After stratification of the patient population by age, sex, diagnosis, and mortality no significant differences for the TLR2 R753Q genotype and TLR4 D299G genotype were found between various patient subgroups and between patient subgroups and the control population. It should be mentioned that for the TLR2 polymorphisms neither the control group nor the patient group contains homozygous mutant individuals. CONCLUSION: We found no association between TLR2 and TLR4 polymorphisms and invasive pneumococcal infection.     

Toll-like receptor polymorphisms and vasculitis susceptibility: meta-analysis and systematic review

The aim of this study was to determine whether toll-like receptor (TLR) polymorphisms confers susceptibility to vasculitis. A literature search was conducted using the PubMed and Embase. A meta-analysis on the associations between the TLR4 Asp299Gly polymorphisms and vasculitis was carried out using allele contrast, dominant, and codominant models and a systematic review of other TLR polymorphisms. Fourteen studies involving 2,064 patients and 2,481 controls were included in this systematic review, which comprised nine on Behcet’s disease (BD), three on giant cell arteritis (GCA), and one on Henoch–Schenlein purpura (HSP). Meta-analysis of six studies showed a significant association between the Gly/Gly+Gly/Asp genotype of the TLR4 Asp299Gly polymorphism and vasculitis and GCA (Odds ratio [OR] = 1.368, 95 % confidence interval [CI] = 1.300–1.815, p = 0.030; OR = 1.523, 95 % CI = 1.099–2.112, p = 0.012). Under a random effects model, the adjusted ORs calculated using the trim and fill technique revealed an association between the Gly/Gly+Gly/Asp genotype of the TLR4 Asp299Gly polymorphism and vasculitis (OR = 1.544, 95 % CI = 1.091–2.185, p < 0.05). Stratification by vasculitis type using the codominant model showed the trend for the association with GCA (OR = 1.569, 95 % CI = 0.970–2.538, p = 0.066). There were three studies on the TLR2 Arg753Gln polymorphism and two on the TLR4 Thr399Ile polymorphism; no association with vasculitis was evident. Among the TLR2, TLR7, and TLR9 polymorphisms included in this review, one Asian study revealed a significant association between the TLR7 rs5743733 and rs3853839 with BD (p = 0.002, 0.036) and one Asian study showed an association of TLR9 rs352140 with BD (p = 0.009). This meta-analysis demonstrates that the TLR4 Asp299Gly polymorphism may confer susceptibility to GCA. The review of published data suggests that other TLR polymorphisms such as TLR7 and TLR9 may play a role in vasculitis.     

NK cell immunophenotypic and genotypic analysis of infants with severe respiratory syncytial virus infection

Respiratory syncytial virus (RSV) is the leading cause of severe lower respiratory tract infection in infants. Reduced numbers of NK cells have been reported in infants with severe RSV infection; however, the precise role of NK cells during acute RSV infection is unclear. In this study the NK and T cell phenotypes, LILRB1 gene polymorphisms and KIR genotypes of infants hospitalized with RSV infection were analyzed. Compared to controls, infants with acute RSV infection showed a higher proportion of LILRB1+ T cells; in addition, a subgroup of infants with RSV infection showed an increase in LILRB1+ NK cells. No differences in NKG2C, NKG2A, or CD161 expression between RSV infected infants and controls were observed. LILRB1 genotype distribution of the rs3760860 A>G, and rs3760861 A>G single nucleotide polymorphisms differed between infants with RSV infection and healthy donors, whereas no differences in any of the KIR genes were observed. Our results suggest that LILRB1 participates in the pathogenesis of RSV infection. Further studies are needed to define the role of LILRB1+ NK in response to RSV and to confirm an association between LILRB1 polymorphisms and the risk of severe RSV infection.     

Polymorphisms in FTO and MAF Genes and Birth Weight,BMI, Ponderal Index,Weight Gain in a Large Cohort of Infants with a Birth Weight below 1500 Grams

Background

The FTO gene, located on chromosome 16q12.2, and the MAF gene, located on chromosome 16q22-23, were identified as genes harboring common variants with an impact on obesity predisposition. We studied the association of common variants with birth weight, gain of body weight, body mass index (BMI), Ponderal index and relevant neonatal outcomes in a large German cohort of infants with a birth weight below 1500 grams.

Methods

The single nucleotide polymorphisms rs9939609 (FTO gene) and rs1424233 (MAF gene) were genotyped using allelic discrimination assays in a prospective multicenter cohort study conducted in 15 neonatal intensive care units in Germany from September 2003 until January 2008. DNA samples were extracted from buccal swabs according to standard protocols.

Results

1946 infants were successfully genotyped at FTO and 2149 infants at MAF. Allele frequencies were not significantly different from other European cohorts. The polymorphisms were in Hardy-Weinberg equilibrium. The polymorphisms did not show associations with birth weight, BMI and Ponderal Index at discharge, and weight gain, neither testing for a dominant, additive nor for a recessive model.

Discussion

Since an association of the polymorphisms with weight gain has been demonstrated in multiple populations, the lack of association in a population of preterm infants with regular tube feeding after birth and highly controlled feeding volumes provides evidence for the hypothesis that these polymorphisms affect food intake behavior and hunger rather than metabolism and energy consumption.     

CD14-159 and -260 gene polymorphisms are associated with HBV-related cirrhotic injury in Chinese Han patients

The present study aimed to investigate the association between TLR4 mutations (Asp299Gly and Thr399Ile) and CD14 polymorphisms (base pair -159 and -260) with HBV-related cirrhosis in Chinese Han patients. By use of a polymerase chain reaction-based restriction fragment length polymorphism (PCR-RFLP) analysis technique, we genotyped Toll-like receptor 4 (TLR4) Asp299Gly and Thr399Ile and CD14-159 and -260 polymorphisms in 110 HBV-related cirrhotic patients and 110 healthy controls from the Chinese Han population. We found significant differences in the genotypes and allele frequencies of CD14-159 (but not -260) between healthy controls and liver cirrhotic patients, and both the CD14-159 and -260 genotypes were significantly different among Child-Pugh grades in cirrhotic patients. No TLR4 Asp299Gly and Thr399Ile mutations were detected in any cirrhotic patients or healthy controls in the Chinese Han population. These findings indicated that the polymorphisms of CD14, but not TLR4 Asp299Gly and Thr399Ile mutations, may be an important genetic factor for HBV-related cirrhotic injury in the Chinese Han population.     

Prospective Validation of a Prognostic Model for Respiratory Syncytial Virus Bronchiolitis in Late Preterm Infants: A Multicenter Birth Cohort Study

Objectives

This study aimed to update and validate a prediction rule for respiratory syncytial virus (RSV) hospitalization in preterm infants 33–35 weeks gestational age (WGA).

Study Design

The RISK study consisted of 2 multicenter prospective birth cohorts in 41 hospitals. Risk factors were assessed at birth among healthy preterm infants 33–35 WGA. All hospitalizations for respiratory tract infection were screened for proven RSV infection by immunofluorescence or polymerase chain reaction. Multivariate logistic regression analysis was used to update an existing prediction model in the derivation cohort (n = 1,227). In the validation cohort (n = 1,194), predicted versus actual RSV hospitalization rates were compared to determine validity of the model.

Results

RSV hospitalization risk in both cohorts was comparable (5.7% versus 4.9%). In the derivation cohort, a prediction rule to determine probability of RSV hospitalization was developed using 4 predictors: family atopy (OR 1.9; 95%CI, 1.1–3.2), birth period (OR 2.6; 1.6–4.2), breastfeeding (OR 1.7; 1.0–2.7) and siblings or daycare attendance (OR 4.7; 1.7–13.1). The model showed good discrimination (c-statistic 0.703; 0.64–0.76, 0.702 after bootstrapping). External validation showed good discrimination and calibration (c-statistic 0.678; 0.61–0.74).

Conclusions

Our prospectively validated prediction rule identifies infants at increased RSV hospitalization risk, who may benefit from targeted preventive interventions. This prediction rule can facilitate country-specific, cost-effective use of RSV prophylaxis in late preterm infants.     

Toll-like receptor 4 D299G polymorphism in metabolic disorders: a meta-analysis

The toll-like receptor 4 (TLR4) plays a key role in the activation of innate immune response participating in the recognition of lipopolysaccharides. Changes in the innate immune response are involved in the pathogenesis of some metabolic disorders such as metabolic syndrome and type 2 diabetes mellitus (Met-S and T2DM). It has been recently shown the role of gut microbiota in the perpetuation of both insulin resistance and low-grade chronic inflammation. Some studies have reported that TLR4 D299G polymorphism is associated with metabolic disorders, however results have been inconsistent. Two recent meta-analyses showed that D299G is associated with inflammatory bowel disease and gastrointestinal cancers risk, two pathological states in which the luminal microbial flora-host cells interaction may be implicated. We conducted a systemic review of the published data considering all eligible published studies (six studies with 1696 cases and 3388 controls for D299G) and a meta-analysis was performed to evaluate the association between TLR4 D299G polymorphism and the risk for metabolic disorders. Five studies were identified for T2DM: three corresponding to Caucasian populations and two to mixed populations. The remaining study analyzed Met-S in a Caucasian population. We observed a significant association between D299G polymorphism and metabolic disorders (T2DM and Met-S) risk (OR = 0.566, 95 % CI: 0.347–0.925, p = 0.023) particularly in Caucasians. No association was found in mixed population subgroup. Our meta-analysis identified that the AG/GG genotypes of D299G are associated with decreased metabolic disorders risk.     

Prescribing cycle training intensity from the six-minute walk test for patients with COPD

Background

Surfactant proteins (SP) are important for the innate host defence and essential for a physiological lung function. Several linkage and association studies have investigated the genes coding for different surfactant proteins in the context of pulmonary diseases such as chronic obstructive pulmonary disease or respiratory distress syndrome of preterm infants. In this study we tested whether SP-B was in association with two further pulmonary diseases in children, i. e. severe infections caused by respiratory syncytial virus and bronchial asthma.

Methods

We chose to study five polymorphisms in SP-B: rs2077079 in the promoter region; rs1130866 leading to the amino acid exchange T131I; rs2040349 in intron 8; rs3024801 leading to L176F and rs3024809 resulting in R272H. Statistical analyses made use of the Armitage's trend test for single polymorphisms and FAMHAP and FASTEHPLUS for haplotype analyses.

Results

The polymorphisms rs3024801 and rs3024809 were not present in our study populations. The three other polymorphisms were common and in tight linkage disequilibrium with each other. They did not show association with bronchial asthma or severe RSV infection in the analyses of single polymorphisms. However, haplotypes analyses revealed association of SP-B with severe RSV infection (p = 0.034).

Conclusion

Thus our results indicate a possible involvement of SP-B in the genetic predisposition to severe RSV infections in the German population. In order to determine which of the three polymorphisms constituting the haplotypes is responsible for the association, further case control studies on large populations are necessary. Furthermore, functional analysis need to be conducted.     

Prolonged Seasonality of Respiratory Syncytial Virus Infection among Preterm Infants in a Subtropical Climate

Objective

There is limited epidemiological data on the seasonality of respiratory syncytial virus (RSV) infection in subtropical climates, such as in Taiwan. This study aimed to assess RSV seasonality among children ≤24 months of age in Taiwan. We also assessed factors (gestational age [GA], chronologic age [CA], and bronchopulmonary dysplasia [BPD]) associated with RSV-associated hospitalization in preterm infants to confirm the appropriateness of the novel Taiwanese RSV prophylactic policy.

Study Design

From January 2000 to August 2010, 3572 children aged ≤24-months were admitted to Taipei Mackay Memorial Hospital due to RSV infection. The monthly RSV-associated hospitalization rate among children aged ≤24 months was retrospectively reviewed. Among these children, 378 were born preterm. The associations between GA, CA, and BPD and the incidence of RSV-associated hospitalization in the preterm infants were assessed.

Results

In children aged ≤24 months, the monthly distribution of RSV-associated hospitalization rates revealed a prolonged RSV season with a duration of 10 months. Infants with GAs ≤32 weeks and those who had BPD had the highest rates of RSV hospitalization (P<0.001). Preterm infants were most vulnerable to RSV infection within CA 9 months.

Conclusions

Given that Taiwan has a prolonged (10-month) RSV season, the American Academy of Pediatrics'' recommendations for RSV prophylaxis are not directly applicable. The current Taiwanese guidelines for RSV prophylaxis, which specify palivizumab injection (a total six doses until CA 8–9 months) for preterm infants (those born before 28^6/7 weeks GA or before 35^6/7 weeks GA with BPD), are appropriate. This prophylaxis strategy may be applicable to other countries/regions with subtropical climates.