Association between asthma-related phenotypes and the CC16 A38G polymorphism in an unselected population of young adult Danes

Club Cell Secretory Protein in Lung Disease: Emerging Concepts and Potential Therapeutics

Club cell secretory protein (CCSP), also known as secretoglobin 1A1 (gene name SCGB1A1), is one of the most abundant proteins in the lung, primarily produced by club cells of the distal airway epithelium. At baseline, CCSP is found in large concentrations in lung fluid specimens and can also be detected in the blood and urine. Obstructive lung diseases are generally associated with reduced CCSP levels, thought to be due to decreased CCSP production or club cell depletion. Conversely, several restrictive lung diseases have been found to have increased CCSP levels both in the lung and in the circulation, likely related to club cell dysregulation as well as increasedlung permeability. Recent studies demonstrate multiple mechanisms by which CCSP dampens acute and chronic lung inflammation. Given these anti-inflammatory effects, CCSP represents a novel potential therapeutic modality in lung disease.

CC16 polymorphisms in asthma, asthma subtypes, and asthma control in adults from the Agricultural Lung Health Study

BACKGROUND

The club cell secretory protein (CC16) has anti-inflammatory and antioxidant effects and is a potential early biomarker of lung damage. The CC16 single nucleotide polymorphism (SNP) rs3741240 risk allele (A) has been inconsistently linked to asthma; other tagging SNPs in the gene have not been explored. The aim was to determine whether CC16 tagging polymorphisms are associated with adult asthma, asthma subtypes or asthma control in the Agricultural Lung Health Study (ALHS).

METHODS

The ALHS is an asthma case-control study nested in the Agricultural Health Study cohort. Asthma cases were individuals with current doctor diagnosed asthma, likely undiagnosed asthma, or asthma-COPD overlap defined by questionnaire. We also examined asthma subtypes and asthma control. Five CC16 tagging SNPs were imputed to 1000 Genomes Integrated phase 1 reference panel. Logistic regression was used to estimate associations between CC16 SNPs and asthma outcomes adjusted for covariates.

RESULTS

The sample included 1120 asthma cases and 1926 controls of European ancestry, with a mean age of 63 years. The frequency of the risk genotype (AA) for rs3741240 was 12.5% (n = 382). CC16 rs3741240 was not associated with adult asthma outcomes. A tagging SNP in the CC16 gene, rs12270961 was associated with uncontrolled asthma (n = 208, ORadj= 1.4, 95% CI 1.0, 1.9; p = 0.03).

CONCLUSION

This study, the largest study to investigate associations between CC16 tagging SNPs and asthma phenotypes in adults, did not confirm an association of rs3741240 with adult asthma. A tagging SNP in CC16 suggests a potential relationship with asthma control.

Selection of a Noninvasive Source of Human DNA Envisaging Genotyping Assays in Epidemiological Studies: Urine or Saliva?

Genetic epidemiology requires an appropriate approach to measure genetic variation within the population. The aim of this study was to evaluate the characteristics and genotyping results of DNA extracted from 2 human DNA sources, selected for their rapid and noninvasive sampling, and the use of simple and standardized protocols that are essential for large-scale epidemiologic studies. Saliva and urine samples were collected at the same day from 20 subjects aged 9-10 yr. Genomic DNA was extracted using commercial kits. Quantitative and qualitative evaluation was done by assessing the yield, the purity, and integrity of the extracted DNA. As a proof-of-concept, genotyping was performed targeting CC16 A38G and uteroglobin-related protein 1 (UGRP1)-112G/A. Saliva was found to provide the highest yield and concentration of total DNA extracted. Salivary DNA showed higher purity and a significantly less degraded state compared to urinary DNA. Consequently, the salivary DNA gave better genotyping results than urinary DNA. Therefore, if the choice exists, saliva is the preferred noninvasive matrix for genotyping purposes in large-scale genetic epidemiologic studies. Only in particular cases using urine could nevertheless be considered useful, although specific limitations need to be taken into account.

Gender-dependent association between exhaled nitric oxide and the CC16 38AA genotype in young school children

Background

Studies that investigated the association between the CC16 A38G polymorphism and the risk of asthma yielded conflicting results. The aim of this study among schoolchildren was to assess the relationships of CC16 A38G polymorphism with aeroallergen sensitization and fractional exhaled nitric oxide (FeNO), two outcomes predicting asthma later in life.

Methods

The study included 139 children (72 boys), median age of 7.7. Information on each child's health, lifestyle, and environment was collected through a questionnaire completed by their parents. CC16 genotypes were determined using urinary DNA. We measured FeNO, the CC16 protein in urine and nasal lavage fluid and aeroallergen‐specific immunoglobulin E in nasal mucosa fluid.

Results

Children with the homozygous mutant CC16 38AA genotype had higher odds of increased FeNO (>30 ppb) compared with their peers with the wild‐type genotype 38GG (OR, 9.85; 95% CI, 2.09‐46.4; P = .004). This association was female gender specific (P = .002) not being observed in boys (P = .40). It was also independent of allergic sensitization, which yet emerged as the strongest predictor of FeNO along with the use of bleach for house cleaning. Children with the CC16 38AA genotype had lower covariates‐adjusted urinary CC16 levels than those with 38GG (median, μg/L, 1.17 vs 2.08, P = .02).

Conclusion

Our study suggests that the CC16 38AA allele promotes airway inflammation as measured by FeNO through a gender‐dependent association. Deficient levels of CC16 in the deep lung, measured noninvasively in urine, as a possible proxy for serum CC16, might underlie this promoting effect.

Allele-specific expression identified rs2509956 as a novel long-distance cis-regulatory SNP for SCGB1A1, an important gene for multiple pulmonary diseases

SCGB1A1 (secretoglobin family 1A member 1) is an important protein for multiple pulmonary diseases, especially asthma, chronic obstructive pulmonary disease, and lung cancer. One single-nucleotide polymorphism (SNP) at 5'-untranslated region of SCGB1A1, rs3741240, has been suggested to be associated with reduced protein expression and further asthma susceptibility. However, it was still unclear whether there were other cis-regulatory elements for SCGB1A1 that might further contribute to pulmonary diseases. Allele-specific expression (ASE) is a novel approach to identify the functional region in human genome. In the present study, we measured ASE on rs3741240 in lung tissues and observed a consistent excess of G allele over A (P < 10^-6), which indicated that this SNP or the one(s) in linkage disequilibrium (LD) could regulate SCGB1A1 expression. By analyzing 1000 Genomes Project data for Chinese, one SNP locating ~10.2 kb away and downstream of SCGB1A1, rs2509956, was identified to be in strong LD with rs3741240. Reporter gene assay confirmed that both SNPs could regulate gene expression in the lung cell. By chromosome conformation capture, it was verified that the region surrounding rs2509956 could interact with SCGB1A1 promoter region and act as an enhancer. Through chromatin immunoprecipitation and overexpression assay, the related transcription factor RELA (RELA proto-oncogene, NF-kB subunit) was recognized to bind the region spanning rs2509956. Our work identified a novel long-distance cis-regulatory SNP for SCGB1A1, which might contribute to multiple pulmonary diseases.

The Club Cell Marker SCGB1A1 Downstream of FOXA2 is Reduced in Asthma

Human SCGB1A1 protein has been shown to be significantly reduced in BAL, sputum, and serum from humans with asthma as compared with healthy individuals. However, the mechanism of this reduction and its functional impact have not been entirely elucidated. By mining online datasets, we found that the mRNA of SCGB1A1 was significantly repressed in brushed human airway epithelial cells from individuals with asthma, and this repression appeared to be associated with reduced expression of FOXA2. Consistently, both Scgb1A1 and FoxA2 were downregulated in an ovalbumin-induced mouse model of asthma. Furthermore, compared with wild-type mice, Scgb1a1 knockout mice had increased airway hyperreactivity and inflammation when they were exposed to ovalbumin, confirming the antiinflammatory role of Scgb1a1 in protection against asthma phenotypes. To search for potential asthma-related stimuli of SCGB1A1 repression, we tested T-helper cell type 2 cytokines. Both IL-4 and IL-13 repressed epithelial expression of SCGB1A1 and FOXA2. Importantly, infection of epithelial cells with human rhinovirus similarly reduced expression of these two genes, which suggests that FOXA2 may be the common regulator of SCGB1A1. To establish the causal role of reduced FOXA2 in SCGB1A1 repression, we demonstrated that FOXA2 was required for SCGB1A1 expression at baseline. FOXA2 overexpression was sufficient to drive promoter activity and expression of SCGB1A1 and was also able to restore the repressed SCGB1A1 expression in IL-13-treated or rhinovirus-infected cells. Taken together, these findings suggest that low levels of epithelial SCGB1A1 in asthma are caused by reduced FOXA2 expression.

Relation between serum CC16 levels and asthma predictive index in pre-schoolers with recurrent wheezing

BACKGROUND

Low levels of serum CC16 were reported in asthmatic adults, but the studies on children were scarce and conflicting. The aim of this study was to compare serum CC16 levels in pre-school children with recurrent wheezing assessed using an asthma predictive index (API).

METHODS

We performed a case-control study based on API, with all enrolled pre-school children who had recurrent wheezing episodes (>3 episodes/last year confirmed by a physician) and had presented at one paediatric clinic in Santiago, Chile. The population was divided according to stringent API criteria into positive or negative.

RESULTS

In a one-year period, 60 pre-schoolers were enrolled. After excluding 12, 48 pre-schoolers remained (27 males, age range from 24 to 71 months) and completed the study; 34 were API positive and 14 were API negative. There were no significant differences in demographics between groups. The level of serum CC16 levels for pre-schoolers with a positive API and negative API were (median 9.2 [7.1-11.5] and 9.4 [5.5-10], p=0.26, respectively). The area under the curve for the serum CC16 levels to predict a positive API was 0.6, 95% CI [0.43-0.77], p=0.3. A correlation between serum CC16 levels and age was found (r=0.36 [0.07-0.59], p=0.01], but not between serum CC16 levels and peripheral eosinophils blood.

CONCLUSION

There was no evidence that serum CC16 levels played a role in recurrent wheezing and a positive API in pre-school children. More studies are needed to confirm this finding.

Reaction products of hexamethylene diisocyanate vapors with "self" molecules in the airways of rabbits exposed via tracheostomy

1. Hexamethylenediisocyanate (HDI) is a widely used aliphatic diisocyanate and a well-recognized cause of occupational asthma. 2. "Self" molecules (peptides/proteins) in the lower airways, susceptible to chemical reactivity with HDI, have been hypothesized to play a role in asthma pathogenesis and/or chemical metabolism, but remain poorly characterized. 3. This study employed unique approaches to identify and characterize "self" targets of HDI reactivity in the lower airways. Anesthetized rabbits free breathed through a tracheostomy tube connected to chambers containing either, O2, or O2 plus ∼200 ppb HDI vapors. Following 60 minutes of exposure, the airways were lavaged and the fluid was analyzed by LC-MS and LC-MS/MS. 4. The low-molecular weight (<3 kDa) fraction of HDI exposed, but not control rabbit bronchoalveolar lavage (BAL) fluid identified 783.26 and 476.18 m/z [M+H]+ ions with high energy collision-induced dissociation (HCD) fragmentation patterns consistent with bis glutathione (GSH)-HDI and mono(GSH)-HDI. Proteomic analyses of the high molecular weight (>3 kDa) fraction of exposed rabbit BAL fluid identified HDI modification of specific lysines in uteroglobin (aka clara cell protein) and albumin. 5. In summary, this study utilized a unique approach to chemical vapor exposure in rabbits, to identify HDI reaction products with "self" molecules in the lower airways.

Uteroglobin gene polymorphism (G38A) may be a risk factor in childhood idiopathic nephrotic syndrome

BACKGROUND

Uteroglobin (UG) is a multifunctional protein with anti-inflammatory properties. The aim of this study was to first evaluate the role of UG gene G38A polymorphism in childhood idiopathic nephrotic syndrome (INS), and determine whether this variation may be related to the occurrence of INS or a steroid response.

METHODS

One hundred and thirty-six children diagnosed with INS in Gaziantep University, Department of Pediatric Nephrology, and 70 healthy volunteers were included. Children with INS were divided into two groups: steroid-sensitive (n = 84), and steroid-resistant (n = 52). Samples were examined using the polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) enzyme method.

RESULTS

The distributions of AA, GG, and AG genotypes of UG gene G38A (G/A) were 16.9%, 44.9%, and 38.2% in the all-INS group, whereas they were 14.3%, 48.8%, and 36.9% in the steroid-sensitive INS (SSINS) group compared with 21.1%, 38.5%, and 40.4% in steroid-resistant INS (SRINS), and 5.7%, 41.4%, and 52.9% in controls. The risk of INS was increased almost 4-fold in children with the AA genotype (p = 0.016). The risk of having SSINS was increased 3.5-fold (p = 0.042) whereas the risk of SRINS was increased 4.8-fold in the same genotype (p = 0.014).

CONCLUSIONS

The uteroglobin gene may play an important role in the development of INS, and the AA genotype of UG gene G38A polymorphism was found more frequently in those children. Further studies evaluating all polymorphisms in larger patient groups are needed to exactly determine the effect of UG gene on the development of INS and steroid response in children.

CC16 gene A38G polymorphism and susceptibility to asthma: an updated meta-analysis

OBJECTIVE

To comprehensively evaluate the association between the CC16 gene A38G polymorphism and the risk of asthma.

METHODS

Studies were retrieved from databases including PubMed, EMBASE, Web of Science and the Chinese Biomedical Literature Database according to the inclusive and exclusive criteria. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of the associations.

MATERIALS

Fifteen case-control studies with 1,623 cases and 3,294 controls were recruited for the analysis of the association between the CC16 gene A38G polymorphism and the risk of asthma.

RESULTS

The overall ORs showed no significant associations between the CC16 gene A38G polymorphism and the risk of asthma (AA vs. GG: OR=1.04, 95%CI=0.86-1.25; AG vs. GG: OR=1.08, 95%CI=0.94-1.24; AA + AG vs. GG: OR=1.07, 95%CI=0.94-1.22; AA vs. AG + GG: OR=1.01, 95%CI=0.85-1.19; A vs. G: OR=1.04, 95%CI=0.95-1.14). Moreover, similar results were obtained in the subgroup analysis stratified by ethnicity (Asian: AG vs. GG: OR=1.02, 95%CI=0.87-1.21; Caucasian: AG vs. GG: OR=1.22, 95%CI=0.94-1.57) and age (Child: AG vs. GG: OR=1.21, 95%CI=0.84-1.74; Adult: AG vs. GG: OR=1.06, 95%CI=0.91-1.23).

CONCLUSION

CC16 gene A38G polymorphism is not associated with the risk of asthma.

Surfactant protein D, Club cell protein 16, Pulmonary and activation-regulated chemokine, C-reactive protein, and Fibrinogen biomarker variation in chronic obstructive lung disease

Chronic obstructive pulmonary disease (COPD) is a multifaceted condition that cannot be fully described by the severity of airway obstruction. The limitations of spirometry and clinical history have prompted researchers to investigate a multitude of surrogate biomarkers of disease for the assessment of patients, prediction of risk, and guidance of treatment. The aim of this review is to provide a comprehensive summary of observations for a selection of recently investigated pulmonary inflammatory biomarkers (Surfactant protein D (SP-D), Club cell protein 16 (CC-16), and Pulmonary and activation-regulated chemokine (PARC/CCL-18)) and systemic inflammatory biomarkers (C-reactive protein (CRP) and fibrinogen) with COPD. The relevance of these biomarkers for COPD is discussed in terms of their biological plausibility, their independent association to disease and hard clinical outcomes, their modification by interventions, and whether changes in clinical outcomes are reflected by changes in the biomarker.

Association between CC10 +38A/G polymorphism and asthma risk: A meta-analysis

OBJECTIVES

A number of studies conducted to assess the association between Clara cell 10-kDa protein (CC10) +38A/G polymorphism and susceptibility to asthma have yielded inconsistent and inconclusive results. In the present study, the possible association was assessed by a meta-analysis.

METHODS

Relevant articles were identified for the period ranging from Jan 1998 up to March 2013. Pooled odds ratios (OR) with 95% confidence intervals (CI) were appropriately derived from fixed effects or random-effects models.

RESULTS

Ten case-control studies with a total of 1529 asthma cases and 2399 controls were included in this meta-analysis. The association between CC10 +38A/G polymorphism and asthma risk was determined in dominant model, recessive model, additive model, and codominant model. In dominant model, CC10 +38A/G polymorphism seemed to be associated with elevated asthma risk (OR = 1.62; 95% CI, 1.23-2.12; P = 0.0005). Subgroup analyses by ethnicity also found significant associations between this polymorphism and asthma risk in Asians and Caucasians. RESULTS from other genetic models further identified this possible association.

CONCLUSION

This meta-analysis suggests that CC10 +38A/G polymorphism confers asthma risk.

Increase of club cell (Clara) protein (CC16) in plasma and urine after exercise challenge in asthmatics and healthy controls, and correlations to exhaled breath temperature and exhaled nitric oxide

Exercise is known to affect the airway epithelium through dehydration, followed by a release of mediators, such as club cell (Clara) protein (CC16). The aim of this study was to follow the CC16 levels at repeated time points in plasma and urine after exercise in asthmatic subjects and controls, and to relate the findings to exhaled breath temperature (EBT) and exhaled nitric oxide (NO). Twenty-two asthmatics and 18 healthy subjects performed an exercise challenge test on a treadmill. Lung function, CC16 in plasma and urine, EBT and fractional exhaled NO were investigated before and repeatedly for 60 min after the exercise. The increase in CC16 concentration in plasma was seen already one minute after exercise (p < 0.001) and increased further after 20 (p = 0.009) until 60 min (p = 0.001). An increase in urinary levels of CC16 peaked after 30 min (p < 0.001), and declined after 60 min but were still higher than baseline (p = 0.002). There were no differences in plasma or urine CC16 levels between asthmatics and controls, but males had higher plasma levels compared to females (p < 0.001) at all time points. EBT peaked at 15 min (p < 0.001) and thereafter declined, and FENO50 (p < 0.0001), alveolar NO concentration (p = 0.049) and bronchial flux of NO (p = 0.0055) decreased after exercise. In conclusion, this study shows that CC16 in plasma increased during 60 min after exercise, not synchronized with CC16 levels in urine. CC16 levels in plasma correlated to EBT and exhaled NO, reflecting an overall epithelial involvement. There was no difference between asthmatics and healthy controls, showing a physiological rather than pathophysiological response.

Exercise but not mannitol provocation increases urinary Clara cell protein (CC16) in elite swimmers

Elite swimmers have an increased risk of developing asthma, and exposure to chloramine is believed to be an important trigger factor. The aim of the present study was to explore pathophysiological mechanisms behind induced bronchoconstriction in swimmers exposed to chloramine, before and after swim exercise provocation as well as mannitol provocation. Urinary Clara cell protein (CC16) was used as a possible marker for epithelial stress. 101 elite aspiring swim athletes were investigated and urinary samples were collected before and 1 h after completed exercise and mannitol challenge. CC16, 11β-prostaglandin (PG)F(2α) and leukotriene E(4) (LTE(4)) were measured. Urinary levels of CC16 were clearly increased after exercise challenge, while no reaction was seen after mannitol challenge. Similar to CC16, the level of 11β-PGF(2α) was increased after exercise challenge, but not after mannitol challenge, while LTE(4) was reduced after exercise. There was no significant difference in urinary response between those with a negative compared to positive challenge, but a tendency of increased baseline levels of 11β-PGF(2α) and LTE(4) in individuals with a positive mannitol challenge. The uniform increase of CC16 after swim exercise indicates that CC16 is of importance in epithelial stress, and may as such be an important pathogenic factor behind asthma development in swimmers. The changes seen in urinary levels of 11β-PGF(2α) and LTE(4) indicate a pathophysiological role in both mannitol and exercise challenge.

The importance of environment on respiratory genotype/phenotype relationships in the Inuit

BACKGROUND

Genetic and environmental influences and their interactions are central to asthma pathogenesis. This study aimed to investigate the effects of different macro-environments on asthma genotype-phenotype associations in two geographically separated populations with common ancestry.

METHODS

To accomplish this, two unselected populations of Inuit were recruited, one living in Greenland (n = 618) and the other in Denmark (n = 739). Subjects were genotyped for CD14 C-159T, SCGB1A1 A38G, ADRB2 Arg16Gly and Gln27Glu. The resulting genetic data were analysed for relationships with asthma-related parameters including lung function, ever asthma, atopy, rhinitis and dermatitis.

RESULTS

The results showed contrasting magnitude and direction of genetic associations between the two geographically separate Inuit populations. In Greenland, the ADRB2 16Arg allele was associated with male-specific lower lung function, but in Denmark the same allele was associated with male-specific higher lung function. This allele was also associated with higher incidence of ever asthma in Denmark but not in Greenland. The SCGB1A1 38A allele was associated with lower rhinitis prevalence in Greenland but not in Denmark.

CONCLUSIONS

These associations suggest that environment interacts with candidate asthma genes to modulate asthma pathogenesis in the Inuit.

Opposite gene by environment interactions in Karelia for CD14 and CC16 single nucleotide polymorphisms and allergy

BACKGROUND

Finnish Karelians have a higher prevalence of allergic disease than Russian Karelians. As both populations are generally from the same ethnic group, the Karelian population offers a unique opportunity to analyse genetic and allergic disease interactions between 'Western' and 'Eastern' environments.

OBJECTIVES

We investigated associations between allergic diseases and CD14 and CC16 polymorphisms in Finnish vs Russian Karelian women.

METHODS

Adult female Karelians (330 Finnish and 274 Russian) were recruited, examined for a range of symptoms and conditions including rhinitis, itchy rash, asthma and atopy and genotyped for CD14 C-159T and CC16 A38G.

RESULTS

For both CD14 C-159T and CC16 A38G, the risk allele for atopic phenotypes in Finnish Karelia was the protective allele in Russian Karelia. For CD14 C-159T, an interactive effect on ever itchy rash (P(interaction) = 0.004), itchy rash <12 mo (P(interaction) = 0.001) and dry cough at night in the past 12 months (<12 months) (P(interaction) = 0.011) was found; the risk allele was C in Russians and T in Finns. For CC16 A38G, an interaction was significant for ever rhinitis (P(interaction) = 0.006), rhinitis <12 mo (P(interaction) = 0.004), and marginally significant for ever hayfever (P(interaction) = 0.07), allergic eye symptoms <12 mo (P(interaction) = 0.09); their risk allele was G in Russians and A in Finns.

CONCLUSION

An Eastern vs Western environment appears to exert an effect via opposite alleles on risk of allergic diseases in adult women.

The genetics of atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is a complex genetic disorder influenced by environmental factors. The mode of inheritance and genes involved are not clear.

RESULTS

This report here is focusing on the current progress in searching the disease-susceptibility genes of AD via both the linkage studies and candidate gene approaches. Genome-wide linkage studies have identified multiple susceptibility loci on 3q and 17q. Candidate region linkage studies identify other susceptibility loci on 5q23-33, 11q13, and 13q12-14. At least 28 candidate genes have to date been verified in association studies, but only association with genes of interleukin (IL)-4, IL-13, IL-4RA, mast cell chymase, and serine protease inhibitor, kazal-type 5 have been replicated in more than two different studies. More halpotype tests and family-based association studies may help to shed more light for the candidate gene approach.

CONCLUSION

Determining the candidate susceptibility genes for AD is not only helping understanding the pathophysiology but also affecting the response to therapy, which is important in pharmacogenetics. The effect of environmental trigger may also have to be considered to elucidate the real face of the disease.

Uteroglobin: a steroid-inducible immunomodulatory protein that founded the Secretoglobin superfamily

Blastokinin or uteroglobin (UG) is a steroid-inducible, evolutionarily conserved, secreted protein that has been extensively studied from the standpoint of its structure and molecular biology. However, the physiological function(s) of UG still remains elusive. Isolated from the uterus of rabbits during early pregnancy, UG is the founding member of a growing superfamily of proteins called Secretoglobin (Scgb). Numerous studies demonstrated that UG is a multifunctional protein with antiinflammatory/ immunomodulatory properties. It inhibits soluble phospholipase A(2) activity and binds and perhaps sequesters hydrophobic ligands such as progesterone, retinols, polychlorinated biphenyls, phospholipids, and prostaglandins. In addition to its antiinflammatory activities, UG manifests antichemotactic, antiallergic, antitumorigenic, and embryonic growth-stimulatory activities. The tissue-specific expression of the UG gene is regulated by several steroid hormones, although a nonsteroid hormone, prolactin, further augments its expression in the uterus. The mucosal epithelia of virtually all organs that communicate with the external environment express UG, and it is present in the blood, urine, and other body fluids. Although the physiological functions of this protein are still under investigation, a single nucleotide polymorphism in the UG gene appears to be associated with several inflammatory/autoimmune diseases. Investigations with UG-knockout mice revealed that the absence of this protein leads to phenotypes that suggest its critical homeostatic role(s) against oxidative damage, inflammation, autoimmunity, and cancer. Recent studies on UG-binding proteins (receptors) provide further insight into the multifunctional nature of this protein. Based on its antiinflammatory and antiallergic properties, UG is a potential drug target.

Infant frequent wheezing correlated to Clara cell protein 10 (CC10) polymorphism and concentration, but not allergy sensitization, in a perinatal cohort study

BACKGROUND

Wheezing episodes are common in young infants. However, the molecular mechanism of wheezing is unclear, and very few therapeutic regimens are effective.

OBJECTIVE

This study investigated the genetic and environmental factors predisposing to infant wheezing in a birth cohort study.

METHODS

A cohort of 1211 pregnant women was recruited for this study. Infant wheezing episodes during the first 18 months of life were correlated to parental atopic history, parental smoking, prematurity, CB IgE levels, and the sequence variant (G+38A) of the Clara cell protein 10 (CC10) gene encoding a secretary anti-inflammatory CC10 protein.

RESULTS

Nine hundred eighty-three infants completed umbilical cord blood collection, and 813 infants completed the 18-month postnatal follow-up. Twenty-two percent of the infants experienced at least 1 wheezing episode, and 6.6% of the infants experienced frequent wheezing (> or =3 episodes). Multivariate logistic regression showed that male sex and the CC10 G+38A polymorphism, but not prematurity, CB IgE level, passive smoking, or parental atopy, were predictors of frequent wheezing. Further studies found that infant frequent wheezing was significantly associated with the CC10 +38AA genotype and lower plasma CC10 levels at 18 months of age (P = .046), and infants with acute wheezing episodes had significantly lower CC10 levels than those without (P = .023). No association of wheezing episodes with allergic sensitization was observed in this cohort population.

CONCLUSION

Infant frequent wheezing is associated with the CC10 G+38A polymorphism and lower CC10 levels but not infant atopy.

CLINICAL IMPLICATIONS

Lower CC10 expression, but not allergy sensitization, is involved in the pathogenesis of infant frequent wheezing.

A critical review of the use of Clara cell secretory protein (CC16) as a biomarker of acute or chronic pulmonary effects

Biomarkers associated with asthma aetiology and exacerbation have been sought to shed light on this multifactorial disease. One candidate is the serum concentration of the Clara cell secretory protein (CC16, sometimes referred to as CC10 or uteroglobin). In this review, we examine serum CC16's relation to asthma aetiology and exacerbation. There is evidence that acute exposures to certain pulmonary irritants can cause a transient increase in serum CC16 levels, and limited evidence also suggests that a transient increase in serum CC16 levels can be caused by a localized pulmonary inflammation. Research also indicates that a transient increase in serum CC16 is not associated with measurable pulmonary damage or impairment of pulmonary function. The biological interpretation of chronic changes in serum CC16 is less clear. Changes in serum CC16 concentrations (either transient or chronic) are not specific to any one agent, disease state, or aetiology. This lack of specificity limits the use of serum CC16 as a biomarker of specific exposures. To date, many of the critical issues that must be understood before serum CC16 levels can have an application as a biomarker of effect or exposure have not been adequately addressed.

Inverse relation between nasal fluid Clara Cell Protein 16 levels and symptoms and signs of rhinitis in allergen-challenged patients with intermittent allergic rhinitis

BACKGROUND

Decreased levels of the anti-inflammatory Clara Cell Protein 16 (CC16) are found in intermittent allergic rhinitis (IAR) and asthma. In asthma this decrease has been associated with hyperreactivity and the A38G single nucleotide polymorphism (SNP). The aim of this study was to examine if IAR is associated with signs and symptoms of rhinitis and the A38G SNP.

METHODS

Nasal fluid CC16 was analyzed in 20 patients with IAR before allergen challenge and 1 and 6 h after challenge, and from 28 healthy controls. The A38G SNP was analyzed in 80 patients with IAR and 106 controls. Nasal biopsies were obtained from three subjects in each group for immunohistochemical analysis of CC16.

RESULTS

In the allergen-challenged patients symptoms and rhinoscopic signs of rhinitis increased after 1 h and normalized after 6 h. In contrast, nasal fluid CC16 decreased 1 h after allergen challenge and returned to baseline after 6 h. Nasal fluid CC16 levels did not differ from controls before and 6 h after challenge. Immunohistochemical investigation showed intense CC16 staining in the nasal epithelium of both patients before season and healthy controls, but weak staining in symptomatic patients during season. No significant association between the A38G SNP and IAR was found.

CONCLUSION

There was an inverse relation between nasal fluid CC16 levels and symptoms and signs of rhinitis in allergen-challenged patients with IAR. However, there was no association between IAR and the A38G SNP.

Variations in genetic influences on the development of asthma throughout childhood, adolescence and early adult life

PURPOSE OF REVIEW

Asthma is likely to be due to many aetiological factors, the effect of each varying considerably with age. Now that there are well established candidate genes for asthma, using genetics to examine age-related susceptibility to asthma offers a new approach to understanding the basic underlying mechanisms.

RECENT FINDINGS

Since few long-term, longitudinal asthma studies exist, opportunities to examine age-related genetic susceptibility have been limited, but have produced some specific findings. The CCR5Delta32 polymorphism renders the chemokine receptor nonfunctional and is associated with reduced asthma susceptibility in children but not adults. In CD14 C-159T, the -159C allele has been associated with increased atopy in mid-childhood, but not in young adults. IL-12beta is a promoter polymorphism associated with reduced lung function in girls but not boys in mid-childhood only. Regarding the beta(2)adrenoceptor, results from three studies suggest that Arg16 can be associated with impaired airway function in infancy and Gly16 with asthma and wheeze in mid-childhood.

SUMMARY

Age-related genetic susceptibility studies are likely to make a major contribution to understanding basic mechanisms in asthma, but the limited number of suitable cohorts has meant that to date few studies have been reported.

Uteroglobin-Related Protein 1 and Clara Cell Protein in Induced Sputum of Patients With Asthma and Rhinitis

RATIONALE

Uteroglobin-related protein 1 (UGRP1) and Clara cell protein (CC16), members of the secretoglobin family, increasingly appear to play a role in airway inflammatory response.

OBJECTIVE

To explore levels of UGRP1 and CC16 in induced sputum of patients with asthma and rhinitis.

METHODS

Induced-sputum samples of patients with asthma or rhinitis (n = 32 each; atopic asthma, n = 24; atopic rhinitis, n = 20) and from 19 nonsmoking nonatopic control subjects were analyzed for cytology and levels of UGRP1, CC16, and albumin.

MEASUREMENTS AND MAIN RESULTS

Sputum UGRP1 increased in both asthma and rhinitis, most strikingly so in asthma, in which changes were most significant in atopic individuals. By contrast, sputum CC16 did not change significantly in either condition, although it was positively correlated with UGRP1 in patients and control subjects. Changes in sputum UGRP1 in atopic asthma were not linked to permeability changes reflected by increased albumin levels but correlated positively with sputum macrophages and negatively with eosinophils. The observed differences in UGRP1 and CC16 may be linked to different cell populations being responsible for their secretion; UGRP1 is mainly secreted in larger conducting airways, whereas CC16 is mainly secreted by the nasal and peripheral airways epithelium.

CONCLUSIONS

The increase in UGRP1 but not of CC16 in asthma and rhinitis suggests that UGRP1 may play a role in these inflammatory diseases.

Complex gene-gene interactions in multiple sclerosis: a multifactorial approach reveals associations with inflammatory genes

The complex inheritance involved in multiple sclerosis (MS) risk has been extensively investigated, but our understanding of MS genetics remains rudimentary. In this study, we explore 51 single nucleotide polymorphisms (SNPs) in 36 candidate genes from the inflammatory pathway and test for gene-gene interactions using complementary case-control, discordant sibling pair, and trio family study designs. We used a sample of 421 carefully diagnosed MS cases and 96 unrelated, healthy controls; discordant sibling pairs from 146 multiplex families; and 275 trio families. We used multifactor dimensionality reduction to explore gene-gene interactions. Based on our analyses, we have identified several statistically significant models including both main effect models and two-locus, three-locus, and four-locus epistasis models that predict MS disease risk with between approximately 61% and 85% accuracy. These results suggest that significant epistasis, or gene-gene interactions, may exist even in the absence of statistically significant individual main effects.

No association between the Clara cell secretory protein (CC16) gene polymorphism and personality traits

Clara cell secretory protein (CC16) is an anti-inflammatory protein expressed in the respiratory tract. Several studies have suggested the association between CC16 and mental disturbances, such as schizophrenia, depression, and post-traumatic stress disorder. In the present study, we investigated the association between the CC16 gene A38G polymorphism and personality traits in 214 healthy Japanese subjects. Personality traits were evaluated by using the Revised NEO Personality Inventory (NEO PI-R) and the State-Trait Anxiety Inventory (STAI). As a result, no significant association was observed between the genotypes and the scores of the NEO PI-R or the STAI. The present results suggest that CC16 may not have a major role in the development of personality traits.