Association Between Gasdermin A and Gasdermin B Polymorphisms and Susceptibility to Adult and Childhood Asthma Among Jordanians.

INTRODUCTION: Gasdermin A (GSDMA) and gasdermin B (GSDMB) have been associated with childhood, and to a lesser extent with adult, asthma in many populations. AIMS: In this study, we investigated the association between GSDMA and GSDMB variants and the incidence of adult and childhood asthma among Jordanians. METHODS: Subjects were divided into two groups: adults and children. Within the adult group there were 129 asthma patients and 111 healthy controls. In the pediatric group there were 98 asthma patients and 112 healthy children. Gasdermin A (GSDMA) (rs7212938, T/G) and Gasdermin B (rs7216389, T/C) polymorphisms were genotyped using the PCR-RFLP method. Three analysis models were applied to the genotype data: co-dominant, dominant and recessive. RESULTS: An association between the GSDMB T/C single nucleotide polymorphism (SNP) genotype and the incidence of childhood asthma was found (< 0.05). GSDMB T/C SNP in children also showed a very high tendency toward significance with p = 0.0532 in the single locus analysis. In adults, no significant differences in the allelic frequencies of any of the SNPs analyzed were found between the case and control populations. At the haplotype level, GC haplotype was found to be associated with the risk of asthma in children while none of the tested haplotypes were found to be associated with asthma risk in adults. CONCLUSIONS: The findings of this study confirm the previously reported association between the GSDMB gene and the risk of childhood asthma.

Association between ADAM33 polymorphisms and susceptibility with adult and childhood asthma among Jordanians.

Disintegrin and metalloprotease 33 (ADAM33) have been associated with childhood and adult asthma in many populations. ADAM33 mutations might predispose to altered lung function in early infancy. In this study, we investigated the association between single-nucleotide polymorphisms in ADAM33 and the incidence of adult and childhood asthma among Jordanians. One hundred seven pediatric asthmatic patients, 115 healthy pediatric patient controls, 160 adult asthmatic patients, and 110 healthy adults were enrolled in this study. ADAM33 polymorphisms were genotyped using the polymerase chain reaction/restriction fragment length polymorphism method. A strong association between the V4 genotype and incidence of childhood asthma was found. In the single-locus analyses of asthma risk, V4 C/G single nucleotide polymorphism (SNP) showed a trend toward significance with p=0.07. Interestingly, the CC homozygous mutant genotype frequency was significantly higher in asthmatic subjects (15.9%) than in control subjects (2.6%), resulting in an odds ratio of 7.05. In adult cases, S2, the F+1 and Q-1 genotype showed a significant association (p≤0.05) with the incidence of asthma. Two haplotypes also exhibited a significant association with asthma (p≤0.05). In conclusion, the findings of this study confirm the already reported association between V4 SNP and the incidence of childhood asthma as well as between S2, F+1, and Q-1 SNPs and the incidence of adult asthma in several populations.

Frequency of genetic polymorphisms of ADAM33 and their association with allergic rhinitis among Jordanians.

Allergic rhinitis is a chronic inflammatory disease that is assumed to be due to an interaction between different genetic and/or environmental factors. A disintegrin and metalloprotease domain 33 (ADAM33) has been extensively studied as a susceptibility gene in asthma and has been linked to bronchial hyper-responsiveness. In this study, we investigated the association between ADAM33 single nucleotide polymorphisms and the incidence of allergic rhinitis among the Jordanian population. We conducted a case-control association study on 120 adult individuals diagnosed with allergic rhinitis and 128 normal healthy controls. 8 single-nucleotide polymorphisms in ADAM33 were genotyped using PCR-RFLP method. No significant differences in the allelic frequencies of all SNPs tested between AR patients and the control volunteers were found, although S2 C/G SNP showed a tendency toward significance with P=0.06. On the genotype level significant association were found in the following genotypes: T1 AA, T1 AG, T2 GG, T2 AG, T+1 GG, T+1 AG, V4 CG, S2 CC, S2 CG, Q-1AA. Seven haplotypes were present only within AR patients and eight haplotypes were completely absent from the AR patients. Three haplotypes exhibited significant association with AR P ≤ 0.05, two of them were present only in AR patients. In conclusion, the polymorphisms in the ADAM33 gene are associated with susceptibility to AR in the Jordanian population. Furthermore, the haplotype of the tested SNPs were also associated with the risk of AR.

Nitric oxide production in PCD: possible evidence for differential nitric oxide synthase function.

Primary cilliary dyskinesia (PCD) is characterized by decreased levels of fractional exhaled nitric oxide (FeNO), thought to reflect low activity of airway inducible nitric oxide synthase (iNOS) levels. Alveolar NO (Calv) concentration and bronchial NO (JNO) flux can be calculated from FeNO measured at multiple exhalation flow rates. We hypothesised that whereas bronchial NO would be reduced in PCD due to reduced iNOS function, alveolar NO would reflect endothelial NOS (eNOS) function and be normal. We recorded the medical history; measured FeNO at multiple flow rates (50, 100, 200, 260 ml/sec); and performed spirometry in 24 children (aged 8-16 years). FeNO50 of the PCD children was significantly lower than normal mean (+/-SD) 8.1 +/- 1.3 ppb versus 12.5 +/- 1.6 ppb, P = 0.033. The mean +/- SD values of PCD (n = 24) and normal (n = 20) subjects were respectively: JNO: 383.5 +/- 307.9 versus 650.1 +/- 489 pl/s, P = 0.033, Calv: 1.60 +/- 0.78 versus 1.60 +/- 0.75 ppb, P = NS. We show that Calv is normal in PCD, demonstrating that there is no generalized disorder of NO handling in this condition. This differs from a previous report. Furthermore, we speculate that these data may provide supportive evidence that variable flow NO measurements can assess the relative activity of iNOS and eNOS.

Markers of airway inflammation in primary ciliary dyskinesia studied using exhaled breath condensate.

Macroscopically, the airways in primary ciliary dyskinesia (PCD) are inflamed and infected, and the eventual result is bronchiectasis. The measurement of noninvasive markers of inflammation in PCD may allow determination of mechanisms of tissue damage, and even allow monitoring of therapy. The aim of this study was to measure in exhaled breath condensate (EBC) of children with PCD the concentrations of the neutrophil chemoattractants leukotriene (LT) B4 and interleukin (IL)-8 and the marker of oxidative stress 8-isoprostane (8-IP), and to try determining whether these markers can be used to assess mechanisms of airway inflammation in these patients. Concentrations of LTB4, IL-8, and 8-IP in the EBC of 23 PCD and 11 age-matched healthy children were measured using an enzyme immunoassay (EIA). The children also performed spirometry and underwent sputum induction, the latter for differential cell count. The concentrations of 8-IP in EBC of children with stable PCD were significantly increased compared to normal controls (median, 7.8 pg/ml vs. 3.1 pg/ml; P = 0.004). There was no difference in the median concentrations of EBC LTB4 between PCD subjects and healthy controls (28 pg/ml vs. 28 pg/ml; P = 0.5). IL-8 levels were below the detection limit of the assay, and were not analyzed further. There was no correlation between concentrations of either 8-IP or LTB(4) in EBC and forced expired volume in 1 sec in PCD children. Sputum induction was successful in 83% of the subjects; the median induced sputum neutrophil count was 69% (interquartile range, 59.3-73.6). No significant correlation was found between sputum neutrophils and either EBC 8-IP or LTB4 concentrations in PCD children. This study showed that oxidative stress, as reflected by increased exhaled 8-IP concentration, is increased in PCD children. The mechanism of airway neutrophilia is unclear, but is unlikely to be related to increased production of LTB4, at least in stable PCD patients.

Correlation between cough frequency and airway inflammation in children with primary ciliary dyskinesia.

Cough is common in airway disease. We measured cough frequency in children with primary ciliary dyskinesia (PCD), to determine how accurately families assess this symptom; and to assess the relationship between cough frequency and airway inflammation, measured using induced sputum and exhaled nitric oxide (eNO). Twenty stable PCD children (7 boys), median age 10.8 years (interquartile range (IQR), 9-14), and 10 healthy control children, median age 12 years (IQR, 10.5-12.7), were recruited. ENO was measured using a chemiluminescence analyzer, with sputum induction with 3.5% saline. PCD children underwent ambulatory cough monitoring. Sputum neutrophils were higher in PCD (median, 70.3%; IQR, 55.3-78%) compared to controls (median, 27%; IQR, 24.5-33%; P = 0.004); cough frequency was higher (median episodes, 19; IQR, 11-22.5) compared to healthy children (median episodes, 6.7; IQR, 4.1-10.5; P < 0.001). Forced expiratory volume in 1 sec (FEV(1) percent predicted) and eNO were lower in PCD (median, 63%; IQR, 57-85%; P < 0.0001); eNO (median, 7.1 ppb (IQR, 4.8-19.1 ppb) vs. 12.4 ppb (IQR, 10.3-17.3 ppb), P = 0.043). Parental scoring of day and night cough correlated with recorded cough (r = 0.930, P < 0.0001, daytime; r = 0.711 for nighttime, P = 0.002). Visual analogue score and cough episodes also correlated positively (r = 0.906; P < 0.0001). There was a positive correlation between cough frequency and sputum neutrophil count in PCD (Spearman's r = 0.693, P < 0.002), but not percent FEV(1) or eNO. Stable PCD children have increased cough frequency and neutrophilic airway inflammation. In conclusion, cough frequency correlated with sputum neutrophils but not with FEV1 or eNO.