Gene by Environment Interaction: The -159C/T Polymorphism in the Promoter Region of the CD14 Gene Modifies the Effect of Alcohol Consumption on Serum IgE Levels

Serum concentrations of mast cell tryptase are reduced in heavy drinkers

BACKGROUND

Baseline serum tryptase concentrations are commonly used in clinical practice as a marker of the body's mast cell burden. This study aimed to investigate serum tryptase concentrations in heavy drinkers.

METHODS

Serum tryptase concentrations were determined in 126 heavy drinkers (75% males, median age 47 years) who were admitted to the hospital because of alcohol withdrawal syndrome (n = 60), general symptoms with abnormalities on biochemical tests that indicated acute liver disease (n = 19), complications of advanced liver disease (n = 33), and miscellaneous reasons (n = 14). Results were compared with those of 70 healthy controls (66% males, median age 40 years).

RESULTS

Serum tryptase concentrations were lower in heavy drinkers than in healthy controls (median 2.23 μg/l vs. median 3.25 μg/l, p < 0.001). Ten heavy drinkers (7.9%) had undetectable (<1 μg/l) serum tryptase levels versus none of the healthy controls (p = 0.01). The association of low tryptase levels with heavy drinking was independent of age, gender, and smoking status. Among heavy drinkers, the lowest tryptase concentrations were observed in patients with alcohol withdrawal syndrome and patients with general symptoms with abnormalities on biochemical tests that indicated acute liver disease. Furthermore, serum tryptase concentrations were negatively correlated with markers of acute liver damage or alcohol consumption (serum aspartate aminotransferase and gamma-glutamyl transferase). Atopy (skin prick test positivity) was not associated with serum tryptase concentrations in heavy drinkers.

CONCLUSIONS

Serum concentrations of mast cell tryptase are lower in heavy drinkers than in healthy controls.

Determinants of serum concentrations of lipopolysaccharide-binding protein (LBP) in the adult population: the role of obesity

Background and Aim

Assessment of serum concentration of lipopolysaccharide (LPS)-binding protein (LBP) has been suggested as a useful biomarker to indicate activation of innate immune responses to microbial products. We investigated LBP concentrations and associations with demographics, lifestyle factors, and common metabolic abnormalities in adults. We also examined if LBP concentrations were associated with common polymorphisms in genes coding for LBP (rs2232618), CD14 (rs2569190), and TLR4 (rs4986790), the molecules responsible for the innate immune response to LPS, or serum levels of soluble CD14 (sCD14) and proinflammatory cytokines.

Methods

Serum LBP was measured with a commercial immunoassay in a random sample of the adult population (n = 420, 45% males, age 18–92 years) from a single municipality.

Results

Serum LBP concentrations increased with age (P<0.001) and were higher in individuals who were overweight or obese than in normal-weight individuals (P<0.001). Similarly, LBP concentrations were higher in individuals with metabolic syndrome than in individuals without it (P<0.001). Among metabolic syndrome components, LBP concentrations were independently associated with abdominal obesity (P = 0.002) and low concentrations of HDL-cholesterol (P<0.001). Serum LBP concentrations tended to be independently associated with smoking (P = 0.05), but not with alcohol consumption. Likewise, there was not significant association between LBP concentrations and gene polymorphisms. Concentrations of LBP significantly correlated with serum levels of proinflammatory cytokines (IL-6 and IL-8), sCD14, and with liver enzymes.

Conclusions

Serum LBP concentrations increased with age. Overweight, obesity, and having metabolic syndrome (particularly, low HDL cholesterol levels) were associated with higher LBP concentrations. These findings are consistent with microbial exposure playing a role in these inflammatory, metabolic abnormalities.

Influence of experimental alcohol administration on serum immunoglobulin levels: contrasting effects on IgE and other immunoglobulin classes

In humans, alcoholic liver disease is associated with hypergammaglobulinemia, particularly with high serum concentrations of IgA. Furthermore, alcohol consumption is associated with high concentrations of IgE and low concentrations of IgG. However, there is little experimental evidence to corroborate these observational findings. The objective of the present study was to investigate the potential short-term effects of alcohol administration on serum immunoglobulin concentrations in mice, and the potential influence of sex and strain on these effects. Eight mouse groups were defined by strain (Swiss vs C57BL/6), sex (male vs female), and experimental procedure (alcohol administration vs control diet). Alcohol was administered in a semi-liquid diet (6.5%v/v); control animals received an isocaloric semi-liquid diet. Immunoglobulin concentrations (IgE, IgA, IgM, IgG1, IgG2a, IgG2b, and IgG3) were measured at baseline and weekly thereafter for 4 weeks. Serum Th1 (interferon-gamma) and Th2 (IL-4 and IL-13) cytokines were measured at week 4. We found significant variations in baseline immunoglobulin concentrations depending upon mouse sex and strain. Alcohol administration was quickly followed by an increase in serum IgE concentrations in all experimental groups. IgE increase was correlated with serum IL-13 increase. In contrast, alcohol administration was not associated with significant changes in serum IgA and IgM concentration, and appeared to decrease IgG subclass concentrations. Alcohol effects on immunoglobulin concentrations were independent of mouse strain and sex. In conclusion, alcohol administration in mice had contrasting effects on IgE and other immunoglobulin classes. This experimental evidence confirms observational results in humans.

Polymorphisms of the CD14 genes are associated with susceptibility to alcoholic liver disease in Greek patients

BACKGROUND

The incidence and severity of alcoholic liver disease (ALD) in chronic drinkers has been found to correlate with some environmental factors and especially with the dose of alcohol consumption, but it is obvious that other parameters clearly contribute to individual alcohol susceptibility. Chronic ethanol exposure leads to continuous endotoxin-mediated Toll-like receptor-4 (TLR-4) and CD14 activation and subsequent cytokine release resulting in chronic inflammation with continued hepatocellular damage. Therefore, genetic studies of polymorphism in TLR-4 and CD14 genes seem to be appropriate in determining genetic susceptibility to ALD. Our aim is to evaluate in a series of Greek drinkers, the possible association of polymorphisms in the TLR-4 and CD14 genes with ALD.

METHODS

In 96 patients with ALD polymorphism of TLR-4 and CD14 genes were studied compared with 104 patients with cirrhosis of other etiology, 100 healthy subjects, and 50 patients with a history of alcohol abuse but without liver disease.

RESULTS

No association between ALD and the presence of the Asp299Gly and Thr399Ile polymorphisms in the TLR-4 gene could be documented in our patients. Regarding the CD14 -159 (C/T) genotypes, TT genotype and T allele were found to be overrepresented in alcoholic patients compared with patients with nonalcohol-induced liver disease and healthy controls. On the other side, when compared patients with ALD and patients with alcohol abuse and no liver disease, TT genotype was found to be significantly less frequent. There is no statistically significant association with the presence of the T allele and the severity of ALD, suggesting that CD14 polymorphism does not influence disease severity in advanced stages of the disease.

CONCLUSIONS

In our series in Greek patients with alcohol abuse and alcoholic cirrhosis, a significant negative association with the CD14 endotoxin receptor gene polymorphism (TT genotype) but not with the TLR-4 gene polymorphism was documented.

A longitudinal analysis of circulating stress-related proteins and chronic ethanol self-administration in cynomolgus macaques

BACKGROUND

Alcoholics have alterations in endocrine and immune functions and increased susceptibility to stress-related disorders. A longitudinal analysis of chronic ethanol intake on homeostatic mechanisms is, however, incompletely characterized in primates.

METHODS

Plasma proteins (n = 60; Luminex) and hormones (adrenocorticotropic hormone [ACTH]; cortisol) were repeatedly measured in adult male cynomolgus monkeys (Macaca fascicularis, n = 10) during a 32-month experimental protocol at baseline, during induction of water and ethanol (4% w/v in water) self-administration, after 4 months, and after 12 months of 22-hour daily concurrent access to ethanol and water.

RESULTS

Significant changes were observed in ACTH, cortisol, and 45/60 plasma proteins: a majority (28/45) were suppressed as a function of ethanol self-administration, 8 proteins were elevated, and 9 showed biphasic changes. Cortisol and ACTH were greatest during induction, and correlations between these hormones and plasma proteins varied across the experiment. Pathway analyses implicated nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB) and Janus kinase (JAK)/signal transducer and activator of transcription (STAT) as possible mediators of ethanol-induced effects on immune-related proteins in primates.

CONCLUSIONS

Chronic ethanol consumption in primates leads to an allostatic state of physiological compromise with respect to circulating immune- and stress-related proteins in NF-κB- and STAT/JAK-related pathways in correlation with altered endocrine activity.

Genetic study of the hepcidin gene (HAMP) promoter and functional analysis of the c.-582A > G variant

BACKGROUND

Hepcidin acts as the main regulator of iron homeostasis through regulation of intestinal absorption and macrophage release. Hepcidin deficiency causes iron overload whereas its overproduction is associated with anaemia of chronic diseases. The aims of the study were: to identify genetic variants in the hepcidin gene (HAMP) promoter, to asses the associations between the variants found and iron status parameters, and to functionally study the role on HAMP expression of the most frequent variant.

RESULTS

The sequencing of HAMP promoter from 103 healthy individuals revealed two genetic variants: The c.-153C > T with a frequency of 0.014 for allele T, which is known to reduce hepcidin expression and the c.-582A > G with a 0.218 frequency for allele G. In an additional group of 224 individuals, the c.-582A > G variant genotype showed no association with serum iron, transferrin or ferritin levels.The c.-582G HAMP promoter variant decreased the transcriptional activity by 20% compared to c.-582A variant in cells from the human hepatoma cell line HepG2 when cotransfected with luciferase reporter constructs and plasmid expressing upstream stimulatory factor 1 (USF1) and by 12-14% when cotransfected with plasmid expressing upstream stimulatory factor 2 (USF2).

CONCLUSIONS

The c.-582A > G HAMP promoter variant is not associated with serum iron, transferrin or ferritin levels in the healthy population. The in vitro effect of the c.-582A > G variant resulted in a small reduction of the gene transactivation by allele G compared to allele A. Therefore the effect of the variant on the hepcidin levels in vivo would be likely negligible. Finally, the c.-153C > T variant showed a frequency high enough to be considered when a genetic analysis is done in iron overload patients.

Genetic and environmental contributions to allergen sensitization in a Chinese twin study

BACKGROUND

Allergic disease is on the rise worldwide. Effective prevention of allergic disease requires comprehensive understanding of the factors that contribute to its intermediate phenotypes, such as sensitization to common allergens.

OBJECTIVE

To estimate the degree of genetic and environmental contributions to sensitization to food and aeroallergens.

METHODS

Sensitization was defined as a positive skin prick test to an allergen. We calculated the zygosity-specific concordance rates and odds ratios (ORs) for sensitization to food and aeroallergens in 826 Chinese twin pairs [472 monozygotic (MZ) and 354 dizygotic (DZ)] aged 12-28 years. We also applied structural equation modelling procedures to estimate genetic and environmental influences on sensitization.

RESULTS

The concordance rates and risk of sensitization in one twin given the presence vs. the absence of sensitization in the other twin were higher in MZ twins than those in DZ twins. However, a large number of MZ twins were discordant in sensitization to common allergens. These observations suggest both genetic and environmental factors influence sensitization. Consistently, the estimated heritability and individual environmental components of the liability to sensitization ranged from 0.51 to 0.68 and 0.32 to 0.49, respectively, based on the best-fitted structural equation model. We also observed high phenotypic correlations between sensitization to two aeroallergens (cockroach and dust mite: 0.83) and two food allergens (peanut and shellfish: 0.58), but only moderate correlations for the pairs between sensitization to a food and an aeroallergen (0.31-0.46). The shared genetic and environmental factors between paired sensitizations contribute to the observed correlations.

CONCLUSION

We demonstrated that sensitization to common food and aeroallergens were influenced by both genetic and environmental factors. Moreover, we found that paired allergen sensitizations might share some common sets of genes and environmental factors. This study underscores the need to further delineate unique and/or pleiotropic genetic and environmental factors for allergen sensitization.

Interference of cross-reactive carbohydrates in the determination of specific IgE in alcohol drinkers and strategies to minimize it: the example of latex

BACKGROUND

Cross-reactive carbohydrate determinants (CCDs) are N-glycans in plant and invertebrate proteins that interfere with specific IgE determinations. The prevalence of IgE to Man2XylFucGlcNAc2 (MUXF), the CCD from bromelain, may be increased in heavy drinkers.

OBJECTIVE

To further investigate the relationship of alcohol consumption to CCD specific IgE. Latex was used as an example for investigating CCD interference with in vitro allergy testing and how to minimize the interference by using nonglycosylated recombinant allergens and inhibition assays.

METHODS

We determined the levels of IgE to CCD markers (MUXF and ascorbate oxidase) and natural rubber latex in 270 adults without a history of latex allergy (73 abstainers or occasional drinkers, 76 light drinkers, 47 moderate drinkers, and 74 heavy drinkers). In cases with latex reactivity, we performed inhibition assays with MUXF and screened for IgE to a panel of recombinant latex allergens. Fourteen-day serologic follow-up was available for a subset of individuals.

RESULTS

Moderate to heavy drinkers displayed an increased prevalence of IgE to CCD markers. The presence of CCD specific IgE was closely associated with latex IgE reactivity. Inhibition studies and the absence of reactivity to nonglycosylated recombinant latex allergens indicated CCD interference in latex IgE determinations. Serum levels of specific IgE decreased with alcohol abstention.

CONCLUSIONS

In this population, alcohol consumption is associated with an increased prevalence of IgE reactivity to natural rubber latex due to CCD interference. The use of nonglycosylated recombinant allergens and inhibition assays may help to minimize CCD interference in populations in which IgE to CCDs is common.

Does the relationship between IgE and the CD14 gene depend on ethnicity?

This review considers the data from studies analysing associations between the CD14C-159T single nucleotide polymorphism (SNP) and asthmatic phenotypes and discusses the variability of the conclusions. By searching PubMed and EMBASE for articles on CD14C-159T -related population or family-based association studies, 47 were identified up till September 2007. Collectively, the studies reviewed herein consistently showed population differences in frequencies of the alleles of the SNP, with African descent having the highest C allele frequencies, followed by Caucasians and Asians. The T allele of the SNP was associated with increased sCD14 in some studies but not in others. Inconsistently, the C allele, or even occasionally the T allele, was associated with atopic phenotypes in a population subgroup. There are several explanations for these inconsistencies, including lack of power, linkage disequilibrium, gene-gene interactions, population admixture and gene-environment interactions. If the SNP was associated with functional changes to the coded protein and thus modulating susceptibility to allergic disease, its effect may be modest and dependent on other co-existent, ethnicity-specific, genetic or environmental risk factors.

Serum TNF-alpha levels in relation to alcohol consumption and common TNF gene polymorphisms

Tumor necrosis factor-alpha (TNF-alpha) mediates alcohol-induced organ dysfunction, including alcoholic hepatitis. Variations in the TNF-alpha gene may underlie the individual predisposition to alcoholic liver disease. Measurement of serum TNF-alpha levels has become a routine in clinical practice. The study was aimed at investigating the level of serum TNF-alpha levels in adults and analyzing its relationship with different levels of alcohol consumption, as well as the potential interaction between alcohol consumption and common TNF-alpha gene polymorphisms in relation to TNF-alpha levels and liver disease. Serum TNF-alpha was measured in a random sample of 459 individuals from a general adult population and in 137 hospital-admitted alcoholics. Three common TNF-alpha gene polymorphisms (-238G> A, -308G> A, and -857C> T) were investigated in 419 of these individuals. In the general adult population, the TNF-alpha levels were similar in alcohol abstainers and alcohol drinkers. Alcoholics admitted to the hospital showed the highest TNF-alpha levels, which were correlated with liver dysfunction. We found no evidence of an interaction between alcohol consumption and TNF-alpha gene polymorphisms in relation to TNF-alpha levels. Carriers of the TNF -238A allele tended to have a higher prevalence of advanced liver disease than -238G homozygotes, confirming previous reports. In conclusion, light-to-moderate drinking had no significant effect on the levels of serum TNF-alpha levels. Serum TNF-alpha levels are elevated in alcoholics independently of common TNF gene polymorphisms.

The association between alcohol consumption and biomarkers of alcohol exposure with total serum immunoglobulin E levels

BACKGROUND

A number of studies have shown that self-reported alcohol intake is positively associated with total serum immunoglobin E (IgE) levels. The purpose of the present study was to investigate the association of self-reported alcohol consumption and different biomarkers of alcohol exposure to total serum IgE levels in a general adult population.

METHODS

A total of 3,443 subjects aged 20 to 79 years from the population-based cross-sectional Study of Health in Pomerania (SHIP) were included in the analyses. Information on alcohol consumption and serum carbohydrate-deficient transferrin (CDT), gamma-glutamyl transferase (GGT), aspartate-amino transferase (ASAT), andalanine-amino transferase (ALAT) levels were measured. Multivariable linear regression models were performed separately in atopic and nonatopic subjects.

RESULTS

In nonatopic subjects positive associations between self-reported alcohol consumption as well as all considered biomarkers of alcohol exposure and total serum IgE levels were found. Further the results also suggested positive associations between alcohol consumption as well as alcohol biomarkers and total serum IgE level in atopic subjects, even though not all tests for linear trend reached statistical significance.

CONCLUSIONS

In conclusion, biomarkers of alcohol exposure were positively associated with total serum IgE levels supporting that the positive association between self-reported alcohol intake and IgE levels observed in previous studies is real and not due to misclassification of alcohol intake or confounding by other factors that may be linked to both alcohol intake and total serum IgE levels.

Sensitization to cross-reactive carbohydrate determinants in relation to alcohol consumption

BACKGROUND

Alcohol consumption is associated with increased serum IgE of unknown specificity.

OBJECTIVE

To investigate the prevalence of specific IgE to cross-reactive carbohydrate determinants (CCDs) in adults, and its relation to alcohol consumption.

METHODS

Population-based survey of 457 adults (218 abstainers, 195 light-to-moderate drinkers, 44 heavy drinkers). Specific IgE determinations included a CCD (MUXF(3), the N-glycan of bromelain), pollens (Lolium perenne and Olea europaea), Hymenoptera venoms (Apis mellifera and Vespula spp.), and a mite (Dermatophagoides pteronyssinus). We replicated these studies in an additional sample of alcoholics (n=138). Inhibition assays were performed in selected cases.

RESULTS

In the general population, 5.6% of individuals (95% confidence interval 3.5-7.6%) showed positive (>/=0.35 kU/L) CCD-specific IgE. The levels of CCD-specific IgE were particularly high in heavy drinkers, who also showed a high prevalence of positive IgE to pollens and Hymenoptera venoms, doubling (at least) the prevalence found in alcohol abstainers and light-to-moderate drinkers. The presence of IgE to pollens and Hymenoptera venoms was closely correlated with the presence of CCD-specific IgE. These features were confirmed in the additional sample of alcoholics. Inhibition studies indicated a role of CCD interference in IgE positivity to pollen and Hymenoptera allergens in alcoholics.

CONCLUSIONS

CCD-specific IgE is prevalent in heavy drinkers, and is associated with positive IgE to pollens and Hymenoptera venoms. Specific IgE results should be interpreted with caution in heavy drinkers.