Genetic variations in regulatory pathways of fatty acid and glucose metabolism are associated with obesity phenotypes: a population-based cohort study.

BACKGROUND: As nuclear receptors and transcription factors have an important regulatory function in adipocyte differentiation and fat storage, genetic variation in these key regulators and downstream pathways may be involved in the onset of obesity. OBJECTIVE: To explore associations between single nucleotide polymorphisms (SNPs) in candidate genes from regulatory pathways that control fatty acid and glucose metabolism, and repeated measurements of body mass index (BMI) and waist circumference in a large Dutch study population. METHODS: Data of 327 SNPs across 239 genes were analyzed for 3575 participants of the Doetinchem cohort, who were examined three times during 11 years, using the Illumina Golden Gate assay. Adjusted random coefficient models were used to analyze the relationship between SNPS and obesity phenotypes. False discovery rate q-values were calculated to account for multiple testing. Significance of the associations was defined as a q-value < or = 0.20. RESULTS: Two SNPs (in NR1H4 and SMARCA2 in women only) were significantly associated with both BMI and waist circumference. In addition, two SNPs (in SIRT1 and SCAP in women only) were associated with BMI alone. A functional SNP, in IL6, was strongly associated with waist. CONCLUSION: In this explorative study among participants of a large population-based cohort, five SNPs, mainly located in transcription mediator genes, were strongly associated with obesity phenotypes. The results from whole genome and candidate gene studies support the potential role of NR1H4, SIRT1, SMARCA2 and IL6 in obesity. Although replication of our findings and further research on the functionality of these SNPs and underlying mechanism is necessary, our data indirectly suggest a role of GATA transcription factors in weight control.

Genetic mapping of two blood pressure quantitative trait loci on rat chromosome 1.

A genetic map for rat chromosome 1 was constructed using 66 microsatellite markers typed on either or both of two populations derived from inbred Dahl salt-sensitive (S) rats: F2(LEW x S) n = 151, and F2(WKY x S) n = 159. These populations had been raised on a high salt (8% NaCl) diet. Systolic blood pressure and heart weight were found to be genetically linked to two separate regions on rat chromosome 1 in the F2(LEW x S) population. One region was centered around the anonymous SA locus and accounted for 24 mmHg of blood pressure. The other region was 55 cM from the SA locus centered around a cluster of cytochromes P450 loci, and accounted for 30 mmHg of blood pressure. Since blood pressure and heart weight were highly correlated these same regions were also linked to heart weight. These results were cross-specific as linkage of these chromosome 1 regions to blood pressure and heart weight was not observed in several other F2 populations derived by crossing S and other normotensive control strains. This is presumably due to different alleles and/or different genetic backgrounds in the various populations. The SA region of chromosome 1 was found to influence body weight in F2(LEW x S) rats. Combining the present data with our previously published data on the F2(LEW x S) population showed that four separate quantitative trait loci with additive effects accounted for 106 mmHg and 38% of the total variance of blood pressure and for 506 mg and 34% of the total variance of heart wt.

Genetic variation in the response to vaccination.

Vaccines are the most powerful means to prevent and diminish the burden of infectious disease. However, there are limitations to their use: vaccines are not yet available for all infectious diseases (including human immunodeficiency virus and respiratory syncytial virus), they sometimes lack efficacy, the response to vaccination is limited by maternal antibodies in very young infants, and the response to vaccination is variable or may even be absent in some individuals. This review focuses on genetic factors that determine the variable response to vaccination. The highly polymorphic human leukocyte antigen system, which is involved in antigen presentation, has been researched most in this aspect, and clearly affects the response to vaccination. Other, but less polymorphic pathways involved are the Toll-like receptor pathway, which is involved in antigen recognition and stimulation of the immune system, and the cytokine immunoregulatory network. The heritability, or the proportion of total variance that is due to additive genetic factors, appears to be particularly large for vaccine-induced antibody responses in young infants compared with cell-mediated responses and antibody responses in older, immunologically more mature individuals. Both antibody and cell-mediated responses are not only affected by loci within, but also strongly by loci outside the human leukocyte antigen system. Because most genes that are important in influencing immune responses to vaccination are still unknown, clearly more work is required. A better understanding of the factors that determine an effective response to vaccination may lead to the identification of specific genes and pathways as targets for the development of novel more uniformly effective vaccines.

[Effect of genetic polymorphisms on the susceptibility to and course of infectious diseases]. / Invloed van genetische polymorfismen op de gevoeligheid voor en het beloop van infectieziekten.

The highly variable susceptibility to and course of infectious diseases are caused by variable environmental factors and by genetic differences in both the pathogens and the host. The genetic variability of the host is determined mainly by polymorphisms in genes that play a role in processes such as adhesion, specific and non-specific immunity, antigen presentation, and inflammation. These variations are important, for example, in infections with HIV or respiratory syncytial virus. It is important to combine genetic knowledge with knowledge about the functional properties of variant genes. Applications of knowledge about genetic variability can be found in the development of vaccines and therapeutic agents, prognostics, and the treatment of individual patients.

beta2-adrenergic receptor polymorphisms and salbutamol-stimulated energy expenditure.

The beta-adrenergic system is involved in the control of energy metabolism and expenditure. The beta2-adrenergic receptor (beta2-AR) gene shows polymorphisms that have been associated with obesity in several studies. In vitro and in vivo studies suggest differences in beta2-AR-mediated function between these polymorphisms. The aim of this study was to investigate the influence of genetic variation in codon 16 of the beta2-AR gene on energy metabolism in humans. Thirty-four subjects were recruited [Gly16Gly (n = 13), Gly16Arg (n = 16), or Arg16Arg (n = 5)]. The beta2-AR was stimulated with two doses of salbutamol (50 and 100 ng/kg fat-free mass per minute) after blockade of the beta1-adrenergic receptors with atenolol. Energy expenditure and plasma substrate and hormone concentrations were measured. The increase in energy expenditure (DeltaEE) was significantly different among groups in which the Arg16Arg group showed the lowest increase (P < 0.05 vs. Gly carriers). In a multiple regression model, variations in the increase in nonesterified fatty acid concentration during salbutamol infusion (partial r = 0.51) and the polymorphism contributed significantly to the variation in DeltaEE. Thirty-five percent of the variation in DeltaEE was explained by these two factors. We conclude that subjects with the Arg16Arg polymorphism of the beta2-AR gene have a reduced thermogenic response to beta2-adrenergic stimulation. Although this relatively small study needs confirmation, the findings support a role for this polymorphism in the development and maintenance of overweight and obesity.

Epididymal sperm aneuploidies in three strains of rats detected by multicolor fluorescence in situ hybridization.

A multicolor fluorescence in situ hybridization (FISH) method was developed to detect aneuploidy and diploidy in epididymal sperm of rats using DNA probes specific for chromosomes 4 and Y. Fourteen healthy young-adult rats from three strains were evaluated: inbred Fisher 344/N/ehs, outbred Sprague-Dawley, and outbred WU Wistar/CPB. The hybridization efficiency of the FISH procedure was > 99.9%, the sex-ratio in sperm was approximately 1 as expected, and there was no significant variation among two independent scorers. No significant variations were detected within or among strains in the frequencies of sperm disomy for chromosome 4 (1-6.5 per 10,000 cell per animal) or the Y chromosome (0-2.5 per 10,000 cells per animal). There was a trend toward increased variation among Wistar rats. The frequencies of sperm-carrying hyper- and hypohaploidy for chromosome 4 were similar, suggesting a symmetrical mechanism of chromosome gain and loss during meiosis. The frequencies of Y-Y-4-4 sperm, which represent genomic meiosis II errors, did not differ significantly across strains (0.1-0.7 per 10,000 cells per strain). This FISH method for detecting aneuploidy in rat epididymal sperm provides a promising interspecies biomarker of male germ cell aneuploidy and introduces the rat as an animal model for investigating the heritable risk to offspring associated with paternal genotype, physiology, and exposure to environmental mutagens. There appear to be no significant differences among young healthy rats, mice, and men in the baseline frequencies of sperm with Y chromosomal disomy, the only chromosome for which data currently exists for all three species.

Mutations induced by 60Co gamma-irradiation in double-stranded M13 bacteriophage DNA in nitrous-oxide saturated solutions are characterized by a high specificity.

Irradiation of double-stranded M13 mp10 DNA in a diluted aqueous solution under N2O leads to a very specific mutation spectrum. Fifteen of 28 mutations induced in a 144 base pair (bp) target are C/G to G/C transversions, the other five bp substitutions are C/G to A/T transversions. Six mutations were single bp deletions, one is a large deletion of 180 bp and one is a 10 bp duplication which is probably from spontaneous origin. The mutations are not randomly distributed throughout the 144 bp mutation target but concentrated around two sites. The differences and similarities with the radiation-induced mutation spectrum previously obtained under oxygen are discussed.

The isolation of rat chromosome probes and their application in cytogenetic tests.

This paper reviews the rat chromosome probes which have so far been isolated in our laboratory. The probes can be divided in three groups: a centromere specific probe, chromosome-specific point probes and chromosome-specific paint probes. The centromere probe 18-5 (member of the rat satellite I family) recognizes the centromeres of 16 of the 21 different rat chromosomes and has proved to be very useful for the detection of centromeres in micronuclei. Chromosome-specific point probes are now available for a least 10 different chromosomes. Four of these probes (hybridizing on chromosome 4, 19 (2 different probes) and Y) have proved to be very useful for the detection of aneuploidy. Finally, paint probes which find their application in the detection of structural chromosome aberrations, such as translocations, have been isolated for all rat chromosomes except chromosomes 11 and 13-16.

Analysis of DES-induced micronuclei in binucleated rat fibroblasts: comparison between FISH with a rat satellite I probe and immunocytochemical staining with CREST serum.

The usefulness of fluorescence in situ hybridization (FISH) with rat satellite I DNA was compared with immunocytochemical staining with CREST serum for the analysis of the content of micronuclei from primary rat fibroblasts. We analyzed micronuclei induced in vitro by the aneugenic compound diethylstilbestrol (DES) or the clastogenic compound mitomycin C (MMC). Since a centromeric probe was not available for the rat, we isolated rat satellite I DNA by PCR with primers designed on the basis of the known rat satellite I DNA sequence. The PCR products obtained as well as the cloned PCR products showed hybridization to the centromeric regions of a large number of chromosomes, but not of chromosome 1, 19, 20, X and Y. Clone 18-5 was further analyzed and was shown to contain at least 4 repeats of the rat satellite I family. This probe, which hybridizes in the centromeric region of 34 of the 42 chromosomes, was used throughout the study as a probe for the FISH analysis of the micronuclei. For the immunocytochemical staining, the commonly used commercial anti-centromeric antibodies could not be used because of the weakness of the fluorescent signals given. Consequently, CREST serum of a single patient was used, which showed bright and distinct signals on the kinetochores of each chromosome. After treatment of the cells with the aneugen DES an increase in centromere (FISH) and kinetochore (CREST) positive micronuclei was found, whereas after treatment with the clastogen MMC, the percentage of centromere-positive micronuclei was similar to that observed in controls. Analysis of a large number of DES-induced micronuclei showed that the immunocytochemical method is equally as or slightly less sensitive for the detection of chromosomes in micronuclei and we therefore recommend FISH with probe 18-5 for the detection of chromosome loss in rat cells.

Mutational specificity of oxidative DNA damage.

In this paper we describe our studies on the mutagenic consequences of oxidative DNA damage introduced by radiation-induced OH radicals (.OH) and by exposure to singlet oxygen (1O2), released by thermo-dissociation of the endoperoxide 3,3'-(1,4-naphthalidene) dipropionate (NDPO2). We have made use of M13mp10 bacteriophage and pUC18 plasmid DNA, containing a 144 base pair (bp) insert in the lacZ alpha gene. This 144 bp insert was used as a mutational target sequence. When dilute aqueous solutions of double-stranded (ds) M13mp10 (plus 144 bp insert) were gamma-irradiated in the presence of oxygen (O2; 100% .OH) or nitrous oxide (N2O; 90% .OH, 10% .H), very specific mutation spectra were found. Mainly bp substitutions were observed, of which C/G to G/C transversions are the predominant type. Moreover, the mutations are for the most part concentrated into two mutational hot spots: a minor and major one. Differences between the oxic (O2) and anoxic (N2O) mutation spectra could also be observed. Under N2O-1 bp deletions were detected, which are absent in the presence of O2, and in the anoxic spectrum more C/G to A/T transversions are present. To investigate whether these differences were due to the small amount of H radicals, which are formed under N2O, ds M13mp10 (plus 144 bp insert) was exposed to gamma-rays in phosphate buffer under nitrogen (55% .H, 45% .OH). Under these conditions a remarkable shift was observed from C/G-->G/C to C/G-->A/T transversions, while the mutations were far more scattered along the 144 bp sequence and no -1 bp deletions were detected. These results strongly suggest that H radicals do not cause -1 bp deletions, but may be responsible for the observed C/G to A/T transversions. The kind of bp substitution not only appeared to be dependent on the type of the water radicals, but also appeared to be strongly influenced by the replicon in which the target sequence is incorporated. When an oxygenated solution of pUC18 plasmid DNA (plus 144 bp insert) is irradiated, mainly C/G to A/T transversions were found at the same major hot spot instead of C/G to G/C transversions when the 144 bp sequence is part of M13mp10 DNA. Finally, in agreement with the observation that 1O2 reacts preferentially with guanine in DNA, a guanine is involved in most of the mutations scored after exposure of single-stranded (ss) M13mp10 DNA to NDPO2-generated 1O2.(ABSTRACT TRUNCATED AT 400 WORDS)

Analysis of micronuclei induced by 1,3-butadiene and its metabolites using fluorescence in situ hybridization.

In our previous study, micronuclei (MN) were induced in bone marrow cells of mice following inhalation exposure to 1300 ppm of 1,3-butadiene (BD) for 6 h per day on 5 consecutive days, and in splenocytes of mice and rats treated intraperitoneally with 80 mg/kg 1,2-epoxybutene (EB) and 30 mg/kg 1,2,3,4-diepoxybutane (DEB), respectively. In the present study, the nature of MN induced by BD, EB and DEB was analyzed by means of fluorescence in situ hybridization (FISH) using mouse minor satellite DNA and rat satellite I DNA as probes. Percentages of MN with centromere signals (MN+) measured following exposures to BD, EB and DEB indicate that these agents are predominantly clastogens. Frequencies of MN+ per 1000 cells suggest that BD, EB and DEB are not only strong clastogens, but also weak aneugens in mice. The weak aneugenic effect of EB and DEB was not observed in rats. Analysis of the number of centromere signals in individual MN, and the size distribution of MN with centromere signals in EB- and DEB-treated animals, and in animals exposed to the positive controls diethylstilbestrol (DES) and mitomycin C (MMC) led to the following conclusions: (1) analysis of MN for the number of centromere signals may be a useful indicator for identifying chemicals with aneugenic properties; (2) there is no correlation between the size of MN and their origin (i.e., chromosome loss/gain or fragment).

The detection and evaluation of aneugenic chemicals.

Although aneuploidy makes a significant contribution to both somatic and inherited disease the mechanisms by which environmental chemicals may induce numerical chromosome aberrations are only poorly defined. The European Union Project was aimed to further our understanding of those chemical interactions with the components of the mitotic and meiotic cell division cycle which may lead to aneuploidy and to characterise the parameters such as cellular metabolism which may influence the activity of aneugenic chemicals. C-mitosis can be induced by the highly lipophilic polychlorinated biphenyl and the completion of mitosis and cleavage can be modified by agents which deplete cellular levels of reduced glutathione. Modifications of the fidelity of chromosome segregation were produced by inhibiting the functioning of topoisomerase II during chromatid separation. In contrast, the modification of centromere integrity resulted in chromosome breakage as opposed to disturbance of segregation. Modifiers of tubulin assembly and centriolar functioning in somatic cells such as acrylamide, vinblastine and diazepam reproduced their activity in rodent bone marrow and male germ cells. The analysis of chromosome malsegregation in Aspergillus nidulans by a structurally related series of halogenated hydrocarbons was used to develop a QSAR model which had high predictive value for the results of fungal tests for previously untested related chemicals. Metabolic studies of potential aneugens in genetically engineered human lymphoblastoid cells demonstrated the detoxification of the aneugenic activity of chloral hydrate and the activation of 2,3-dichlorobutane, 1,1,2-trichloroethane and trichloroethylene by Phase I biotransforming enzymes. Cell transformation studies in Syrian hamster dermal cultures using a panel of 22 reference and or potential aneugens indicated that 15 of the 22 produced positive results following single exposures. Five of the aneugens which were negative following single exposures produced positive results where cultures were continuously exposed for up to 6 weeks to low concentrations following a single non-transforming exposure to the mutagen dimethyl sulphate. The transformation studies indicate that a significant proportion of chemical aneugens are potential complete carcinogens and/or co-carcinogens. To optimise the enumeration of chromosomes following exposure to potential chemical aneugens whole chromosome paints and centromere specific probes suitable for use in fluorescence in situ hybridisation (FISH) were developed for the rat, mouse and Chinese hamster and selected human probes evaluated for their suitability for routine use. Molecular chromosome probes were used to develop protocols for enumerating chromosomes in metaphase cells and centromeres and micronuclei in interphase cells. The analysis of segregation of specific centromeres in binucleate cells following cytochalasin B treatment was shown to be a potentially valuable system for characterising non-disjunction following chemical exposure. Whole chromosome paints and centromere specific probes were used to demonstrate the presence of dose-response thresholds following treatment with a reference panel of spindle inhibiting chemicals. These data indicate that the FISH technology is suitable for evaluating the relative hazards of low-dose exposures to aneugenic chemicals.

Novel insight in the association between salmonellosis or campylobacteriosis and chronic illness, and the role of host genetics in susceptibility to these diseases.

We studied the role of host genetics in the susceptibility to severe Salmonella and Campylobacter infections and chronic sequelae of these infections. Participants of a previous case-control study were sent a buccal swab kit and a questionnaire about occurrence of chronic sequelae. Single nucleotide polymorphisms (SNPs) in the TLR4 (rs4986790), IFNG (rs2430561 and rs1861493), STAT1 (rs1914408), IL1B (rs16944), NRAMP (SLC11A1 rs2276631), JUN (rs11688) and VDR (rs10735810) genes were determined. In total, 687 controls, 457 Campylobacter cases and 193 Salmonella cases participated. None of the SNPs were associated with Campylobacter or Salmonella infections. None of the participants developed Guillain-Barré, Miller-Fisher or Reiter's syndrome. Reactive arthritis occurred in 5% and 2% of cases and controls, respectively. Campylobacter cases more frequently experienced gastroenteritis episodes than controls. Campylobacter or Salmonella infection in women, use of proton pump inhibitors and an SNP in the IFNG gene were independent risk factors for reactive arthritis. Another SNP in the IFNG gene and use of proton pump inhibitors were risk factors for recurrent episodes of gastroenteritis. In conclusion, reactive arthritis and recurrent gastroenteritis episodes are common after infection and host genetic factors play a role in susceptibility to these long-term health effects.

Genetic variation in thioredoxin interacting protein (TXNIP) is associated with hypertriglyceridaemia and blood pressure in diabetes mellitus.

AIMS: Thioredoxin interacting protein (TXNIP) is an attractive candidate gene for diabetes or diabetic dyslipidaemia, since TXNIP is the strongest glucose-responsive gene in pancreatic B-cells, TXNIP deficiency in a mouse model is associated with hyperlipidaemia and TXNIP is located in the 1q21-1q23 chromosomal Type 2 diabetes mellitus (DM) locus. We set out to investigate whether metabolic effects of TXNIP that were previously reported in a murine model are also relevant in human Type 2 DM. METHODS: The frequency distribution of a 3' UTR single nucleotide polymorphism (SNP) in TXNIP was investigated in subjects with normal glucose tolerance (NGT; n = 379), impaired glucose tolerance (IGT; n = 228) and Type 2 DM (n = 230). Metabolic data were used to determine the effect of this SNP on parameters associated with lipid and glucose metabolism. RESULTS: The frequency of the TXNIP variation did not differ between groups, but within the group of diabetic subjects, carriers of the TXNIP-T variant had 1.6-fold higher triglyceride concentrations (P = 0.015; n = 136) and a 5.5-mmHg higher diastolic blood pressure (P = 0.02; n = 212) than homozygous carriers of the common C-allele, whereas in non-diabetic subjects fasting glucose was 0.26 mmol/l lower (P = 0.002; n = 478) in carriers of the T-allele. Moreover, a significant interaction between plasma glucose concentrations and TXNIP polymorphism on plasma triglycerides was observed (P = 0.012; n = 544). CONCLUSION: This is the first report to implicate TXNIP in a human disorder of energy metabolism, Type 2 diabetes. The effect of TXNIP on triglycerides is influenced by plasma glucose concentrations, suggesting that the biological relevance of TXNIP variations may be particularly relevant in recurrent episodes of hyperglycaemia.

Polymorphisms in the NPY and AGRP genes and body fatness in Dutch adults.

OBJECTIVE: To investigate the association between DNA polymorphisms in the NPY and AGRP genes and body fatness. DESIGN AND METHODS: The association between the AGRP Ala67Thr or the NPY Leu7Pro polymorphisms and indicators of body fatness (baseline leptin levels, body mass index (BMI) values and prevalence of overweight) are investigated in 582 participants of two large cohorts in The Netherlands (total 18 500 adult men and women), aged 20-40 years whose weight remained relatively constant or whose weight increased substantially (range 5.5-47 kg) during a mean follow-up of 7 years. RESULTS: No consistent associations were found for the indicators of body fatness for men and women. Among women, BMI values, leptin levels and prevalence of overweight were not statistically different for carriers of the mutant alleles compared to that of the non-carriers. Among men, carriers of the Thr67-allele of the AGRP gene had similar leptin levels, but higher BMI values compared to those with the genotyping Ala67/Ala67: mean adjusted BMI 25.6 kg/m2 (95% CI 24.3-27.0) vs 23.9 kg/m2 (23.6-24.3). Also, the risk of being overweight at baseline tended to be higher for male carriers of the Thr67-allele of the AGRP gene (OR 2.52; 95% CI 0.86-7.4). Furthermore, male carriers of the Pro7-allele of the NPY gene had on average higher leptin levels and BMI values vs non-carriers of this allele: 4.7 microg/l (95% CI 3.7-6.0) and 25.7 kg/m2 (95% CI 24.4-27.0) vs 3.1 microg/l (95% CI 2.9-3.4) and 23.9 kg/m2 (95% CI 23.5-24.3), respectively. These male carriers had also a higher risk on being overweight at baseline (OR 3.3 (95% CI 1.2-8.9)) compared to non-carriers of the Pro7-allele. CONCLUSION: The consistent findings among men suggest that the NPY Leu7Pro polymorphism (or another linked marker) might be involved in the development of obesity at younger ages. The findings for the AGRP Ala67Thr were less consistent and need further investigation. Among women, these polymorphisms do not play an important role.

Host genetics of Bordetella pertussis infection in mice: significance of Toll-like receptor 4 in genetic susceptibility and pathobiology.

The susceptibility to and the severity of Bordetella pertussis infections in infants and children varies widely, suggesting that genetic differences between individuals influence the course of infection. We have previously identified three novel loci that influence the severity of whooping cough by using recombinant congenic strains of mice: Bordetella pertussis susceptibility loci 1, 2, and 3 (Bps1, -2, and -3). Because these loci could not account for all genetic differences between mice, we extended our search for additional susceptibility loci. We therefore screened 11 inbred strains of mice for susceptibility to a pertussis infection after intranasal infection. Susceptibility was defined by the number of bacteria in the lungs, being indicative of the effect between the clearance and replication of bacteria. The most resistant (A/J) and the most susceptible (C3H/HeJ) strains were selected for further genetic and phenotypic characterization. The link between bacterial clearance and chromosomal location was investigated with 300 F2 mice, generated by crossing A/J and C3H/HeJ mice. We found a link between the delayed clearance of bacteria from the lung and a large part of chromosome 4 in F2 mice with a maximum log of the odds score of 33.6 at 65.4 Mb, which is the location of Tlr4. C3H/HeJ mice carry a functional mutation in the intracellular domain of Tlr4. This locus accounted for all detectable genetic differences between these strains. Compared to A/J mice, C3H/HeJ mice showed a delayed clearance of bacteria from the lung, a higher relative lung weight, and increased body weight loss. Splenocytes from infected C3H/HeJ mice produced almost no interleukin-1beta (IL-1beta) and tumor necrosis factor alpha (TNF-alpha) upon ex vivo restimulation with B. pertussis compared to A/J mice and also showed a delayed gamma interferon (IFN-gamma) production. TNF-alpha expression in the lungs 3 days after infection was increased fivefold compared to uninfected controls in A/J mice and was not affected in C3H/HeJ mice. In conclusion, Tlr4 is a major host factor explaining the differences in the course of infection between these inbred strains of mice. Functional Tlr4 is essential for an efficient IL-1-beta, TNF-alpha, and IFN-gamma response; efficient clearance of bacteria from the lung; and reduced lung pathology.

Genetic control of Bordetella pertussis infection: identification of susceptibility loci using recombinant congenic strains of mice.

Susceptibility to and severity of Bordetella pertussis infection in infants and children vary widely. The spectrum of clinical symptoms ranges from subclinical infection to mild disease, severe whooping cough, and death. The aims of this study were to examine genetic susceptibilities of mice to B. pertussis and to identify genetic loci in the mouse genome that are involved in susceptibility to B. pertussis infection. For this purpose we screened two sets of recombinant congenic strains (RCS) of mice, HcB and CcS, for differences in the numbers of bacteria in the lung 7 days after inoculation. For both CcS and in HcB mice, a wide range in numbers of bacteria in the lung was found, suggesting that the course of infection is under multigenic control. From both RCS sets of mice, we selected one strain to identify possible susceptibility loci in F(2) hybrid mice. The degree of lung colonization 7 days postinoculation in these F(2) mice was evaluated in relation to genetic markers by linkage analysis. We found three novel loci that are involved in the control of B. pertussis infection. One locus, designated B. pertussis susceptibility locus 1 (Bps-1), was identified on chromosome 12. The presence of the C57BL/10 genome on this locus instead of the C3H genome significantly decreased the number of B. pertussis bacteria in the lung. Bps-1 has a dominant-positive effect on the clearance of B. pertussis from the lung. The function of most genes in this region is unknown. Two other loci, Bps-2 and Bps-3, showed genetic interaction and are located on chromosomes 5 and 11. We aim to identify the gene(s) in these regions which modify susceptibility to B. pertussis.

Influence of beta(2)-adrenoceptor gene polymorphisms on diet-induced thermogenesis.

The sympathetic nervous system is involved in the control of energy metabolism and expenditure. Diet-induced thermogenesis is mediated partly by the ss-adrenergic component of this system. The aim of the present study was to investigate the role of genetic variation in the beta(2)-adrenoceptor in diet-induced thermogenesis. Data from twenty-four subjects (fourteen men and ten women; BMI 26.7(sem 0.8) kg/m(2); age 45.2(sem1.4) years) with different polymorphisms of the beta(2)-adrenoceptor at codon 16 (Gly16Gly, Gly16Arg or Arg16Arg) were recruited for this study. Subjects were given a high-carbohydrate liquid meal, and the energy expenditure, respiratory exchange ratio, and plasma concentrations of NEFA, glycerol, glucose, insulin and catecholamines were measured before and over 4 h after the meal. The AUC of energy expenditure (diet-induced thermogenesis) was not significantly different between polymorphism groups, nor was the response of any of the other measured variables to the meal. In a multiple regression model, the only variable that explained a significant proportion (32 %) of the variation in diet-induced thermogenesis was the increase in plasma adrenaline in response to the meal (P<0.05). The beta(2)-adrenoceptor codon16 polymorphisms did not contribute significantly. In conclusion, an independent contribution of the codon 16 polymorphism of the beta(2)-adrenoceptor gene to the variation in thermogenic response to a high-carbohydrate meal could not be demonstrated. The interindividual variation in thermogenic response to the meal was correlated with variations in the plasma adrenaline response to the meal.

Common variants in the ATP-sensitive K+ channel genes KCNJ11 (Kir6.2) and ABCC8 (SUR1) in relation to glucose intolerance: population-based studies and meta-analyses.

AIMS: To evaluate the relation between common variants in the ATP-sensitive K+ channel genes and glucose intolerance. METHODS: We conducted a meta-analysis of reported association studies in Caucasian populations for common variants in the ABCC8 (exons 16 and 18) and the KCNJ11 (E23K) gene and examined sources of heterogeneity in the results. The meta-analysis was based on 7768-10216 subjects (depending on the gene variant), and included two new population-based studies in the Netherlands with 725 cases and 742 controls. RESULTS: For the KCNJ11 variant, the summary odds ratio (OR) for glucose intolerance was 1.12 (1.01-1.23, P=0.03) for the EK genotype and 1.44 (1.17-1.78, P=0.0007) for the KK genotype, as compared with the EE genotype. For the ABCC8 exon 16 variant, the OR was 1.06 (0.94-1.19, P=0.34) for ct and 0.93 (0.71-1.20, P=0.56) for tt, as compared with the cc genotype. For ABCC8 exon 18, the OR was 1.20 (0.97-1.49, P=0.10) for CT/TT, as compared with the CC genotype. Studies of the ABCC8 variants that were published first or had smaller sample sizes (for the exon 18 variant) showed stronger associations, which may indicate publication bias. For the ABCC8 exon 18 and the KCNJ11 variant, associations were stronger for studies of clinical diabetes than newly detected glucose intolerance. The population attributable risk for clinical Type 2 diabetes was 6.2% for the KCNJ11 KK genotype and 10.1% for the KCNJ11 EK and KK genotype combined. CONCLUSIONS: The common KCNJ11 E23K gene variant, but not the ABCC8 exon 16 or exon 18 variant, was consistently associated with Type 2 diabetes.

A new rat repetitive DNA family shows preferential localization on chromosome 3, 12 and Y after fluorescence in situ hybridization and contains a subfamily which is Y chromosome specific.

A DNA segment, containing a so far unknown repetitive DNA sequence has been isolated by reassociation of sheared total rat genomic DNA. FISH with this probe gave a strong hybridization signal on the satellites and in the centromeric region of chromosomes 3 and 12 and on the q-arm of the Y chromosome. A much weaker signal was seen in the centromeric region of chromosomes 11, 19 and X. The repeat unit of this repetitive DNA sequence is a 195-200 bp monomer, which is tandemly repeated. Screening of a rat genomic lambda library resulted in the isolation of variant members of this repeat family. FISH results with these members showed differences in their hybridization pattern especially when posthybridization washings were performed under higher stringency. Under these conditions one phage gave a strong hybridization signal only on the Y chromosome; other phage showed only weak hybridization patterns on different chromosomes. A subclone of the Y-specific phage was sequenced and showed large sequence homology with the 195-200 bp monomer. In Southern blot experiments this Y-specific sequence detects several male specific sequences, although some cross-hybridization with closely related sequences in both male and female DNA can also be observed.