Atherothrombosis and Thromboembolism: Position Paper from the Second Maastricht Consensus Conference on Thrombosis.

Atherothrombosis is a leading cause of cardiovascular mortality and long-term morbidity. Platelets and coagulation proteases, interacting with circulating cells and in different vascular beds, modify several complex pathologies including atherosclerosis. In the second Maastricht Consensus Conference on Thrombosis, this theme was addressed by diverse scientists from bench to bedside. All presentations were discussed with audience members and the results of these discussions were incorporated in the final document that presents a state-of-the-art reflection of expert opinions and consensus recommendations regarding the following five topics: 1. Risk factors, biomarkers and plaque instability: In atherothrombosis research, more focus on the contribution of specific risk factors like ectopic fat needs to be considered; definitions of atherothrombosis are important distinguishing different phases of disease, including plaque (in)stability; proteomic and metabolomics data are to be added to genetic information. 2. Circulating cells including platelets and atherothrombosis: Mechanisms of leukocyte and macrophage plasticity, migration, and transformation in murine atherosclerosis need to be considered; disease mechanism-based biomarkers need to be identified; experimental systems are needed that incorporate whole-blood flow to understand how red blood cells influence thrombus formation and stability; knowledge on platelet heterogeneity and priming conditions needs to be translated toward the in vivo situation. 3. Coagulation proteases, fibrin(ogen) and thrombus formation: The role of factor (F) XI in thrombosis including the lower margins of this factor related to safe and effective antithrombotic therapy needs to be established; FXI is a key regulator in linking platelets, thrombin generation, and inflammatory mechanisms in a renin-angiotensin dependent manner; however, the impact on thrombin-dependent PAR signaling needs further study; the fundamental mechanisms in FXIII biology and biochemistry and its impact on thrombus biophysical characteristics need to be explored; the interactions of red cells and fibrin formation and its consequences for thrombus formation and lysis need to be addressed. Platelet-fibrin interactions are pivotal determinants of clot formation and stability with potential therapeutic consequences. 4. Preventive and acute treatment of atherothrombosis and arterial embolism; novel ways and tailoring? The role of protease-activated receptor (PAR)-4 vis à vis PAR-1 as target for antithrombotic therapy merits study; ongoing trials on platelet function test-based antiplatelet therapy adjustment support development of practically feasible tests; risk scores for patients with atrial fibrillation need refinement, taking new biomarkers including coagulation into account; risk scores that consider organ system differences in bleeding may have added value; all forms of oral anticoagulant treatment require better organization, including education and emergency access; laboratory testing still needs rapidly available sensitive tests with short turnaround time. 5. Pleiotropy of coagulation proteases, thrombus resolution and ischaemia-reperfusion: Biobanks specifically for thrombus storage and analysis are needed; further studies on novel modified activated protein C-based agents are required including its cytoprotective properties; new avenues for optimizing treatment of patients with ischaemic stroke are needed, also including novel agents that modify fibrinolytic activity (aimed at plasminogen activator inhibitor-1 and thrombin activatable fibrinolysis inhibitor.

Childhood asthma is associated with mutations and gene expression differences of ORMDL genes that can interact.

BACKGROUND: Genomewide association studies identified ORMDL3 as a plausible asthma candidate gene. ORMDL proteins regulate sphingolipid metabolism and ceramide homeostasis and participate in lymphocyte activation and eosinophil recruitment. Strong sequence homology between the three ORMDL genes and ORMDL protein conservation among different species suggest that they may have shared functions. We hypothesized that if single nucleotide polymorphisms (SNPs) in ORMDL3 alter its gene expression and play a role in asthma, variants in ORMDL1 and ORMDL2 might also be associated with asthma. METHODS: Asthma associations of 44 genotyped SNPs were determined in at least 1303 subjects (651 asthmatics). ORMDL expression was evaluated in peripheral blood mononuclear cells (PBMC) from 55 subjects (eight asthmatics) before and after allergen stimulation, and in blood (n = 60, 5 asthmatics). Allele-specific cis-effects on ORMDL expression were assessed. Interactions between human ORMDL proteins were determined in living cells. RESULTS: Sixteen SNPs in all three ORMDLs were associated with asthma (14 in ORMDL3). Baseline expression of ORMDL1 (P = 1.7 × 10(-6) ) and ORMDL2 (P = 4.9 × 10(-5) ) was significantly higher in PBMC from asthmatics, while induction of ORMDLs upon stimulation was stronger in nonasthmatics. Disease-associated alleles (rs8079416, rs4795405, rs3902920) alter ORMDL3 expression. ORMDL proteins formed homo- and heterooligomers and displayed similar patterns of interaction with SERCA2 and SPT1. CONCLUSIONS: Polymorphisms in ORMDL genes are associated with asthma. Asthmatics exhibit increased ORMDL levels, suggesting that ORMDLs contribute to asthma. Formation of heterooligomers and similar interaction patterns with proteins involved in calcium homeostasis and sphingolipid metabolism could indicate shared biological roles of ORMDLs, influencing airway remodeling and hyperresponsiveness.

Tissue factor-independent inhibition of thrombin generation by tissue factor pathway inhibitor-α.

BACKGROUND: Tissue factor pathway inhibitor-α (TFPIα) inhibits factor Xa by forming a binary TFPI-FXa complex in a reaction that is stimulated by protein S. TF-FVIIa forms a quaternary complex with TFPIα and FXa, which shuts off the initiation of coagulation via the extrinsic pathway. AIM: To investigate whether direct inhibition of FXa by TFPIα independently of TF plays a role in downregulating coagulation. METHODS: Inhibition of FXa by TFPIα in plasma was determined by measuring thrombin generation triggered with FXa, the FX activator from Russell's viper venom (RVV-X), FXIa, or FIXa. TF-independent anticoagulant activities of TFPIα and its cofactor, protein S, were quantified: (i) after neutralization of TFPIα and protein S with anti-TFPI or anti-protein S antibodies; and (ii) in TFPI-depleted or protein S-depleted plasmas supplemented with varying amounts of TFPIα or protein S. RESULTS: Both anti-TFPI and anti-protein S antibodies enhanced thrombin generation in plasma triggered with RVV-X, FXa, FIXa, or FXIa. Anti-TFPI and anti-protein S antibodies decreased the lag time and increased the peak height of thrombin generation to the same extent, indicating that inhibition of FXa by TFPIα requires the presence of protein S. TFPIα and protein S titrations in TFPI-depleted or protein S-depleted plasma in which thrombin formation was initiated with triggers other than TF also revealed TF-independent anticoagulant activity of TFPIα, which was completely dependent on the presence of protein S. CONCLUSION: Direct inhibition of FXa by TFPIα contributes to the downregulation of coagulation.

Inhibition of tissue factor:factor VIIa-catalyzed factor IX and factor X activation by TFPI and TFPI constructs.

BACKGROUND: TFPI is a Kunitz-type protease inhibitor that downregulates the extrinsic coagulation pathway by inhibiting factor Xa (FXa) and FVIIa. All three Kunitz domains (KD1, KD2, and KD3) and protein S are required for optimal inhibition of FXa and FVIIa. There is limited information on Kunitz domain requirements of the inhibition of TF:FVIIa-catalyzed FIX and FX activation by TFPI. AIM: To investigate the role of the Kunitz domains of TFPI and protein S in the inhibition of FX and FIX activation. METHODS: Inhibition of TF:FVIIa-catalyzed FX and FIX activation by full-length TFPI (TFPIFL ) and TFPI constructs was quantified from progress curves of FXa and FIXa generation measured with chromogenic substrates. RESULTS AND CONCLUSIONS: TFPIFL inhibited TF:FVIIa-catalyzed FIX activation with a Ki of 16.7 nmol L(-1) . Protein S reduced the Ki to 1.0 nmol L(-1) . TFPI1-150 and KD1-KD2 had 10-fold higher Ki values and were not stimulated by protein S. Single Kunitz domains were poor inhibitors of TF:FVIIa-catalyzed FIX activation (Ki >800 nm). FX activation was measured at limiting FVIIa and excess TF or vice versa. At both conditions, TFPIFL , TFPI1-150 , and KD1-KD2 showed similar inhibition of FX activation. However, at low phospholipid concentrations, TFPIFL was ~ 15-fold more active than TFPI1-150 or KD1-KD2. Apparently, excess phospholipids act as a kind of sink for TFPIFL , limiting its availability for TF:FVIIa inhibition. Preformed FXa:TFPIFL/1-150 complexes rapidly and stoichiometrically inhibited FIX and FX activation by TF:FVIIa, indicating that binary TFPI:FXa complex formation is the limiting step in TF:FVIIa inhibition. Protein S also enhanced inhibition of TF:FVIIa-catalyzed FX activation by TFPI.

Fine-mapping of IgE-associated loci 1q23, 5q31, and 12q13 using 1000 Genomes Project data.

BACKGROUND: Genome-wide association studies (GWAS) repeatedly identified 1q23 (FCER1A), 5q31 (RAD50-IL13 and IL4), and 12q13 (STAT6) as major susceptibility loci influencing the regulation of total serum IgE levels. As GWAS may be insufficient to capture causal variants, we performed fine-mapping and re-genotyping of the three loci using 1000 Genomes Project datasets. METHODS: Linkage disequilibrium tagging polymorphisms and polymorphisms of putative functional relevance were genotyped by chip technology (24 polymorphisms) or MALDI-TOF-MS (40 polymorphisms) in at least 1303 German children (651 asthmatics). The effect of polymorphisms on total serum IgE, IgE percentiles, and atopic diseases was assessed, and a risk score model was applied for gene-by-gene interaction analyses. Functional effects of putative causal variants from these three loci were studied in silico. RESULTS: Associations from GWAS were confirmed and extended. For 1q23 and 5q31, the majority of associations were found with mild to moderately elevated IgE levels, while in the 12q13 locus, single-nucleotide polymorphisms (SNPs) were associated with strongly elevated IgE levels. Gene-by-gene interaction analyses suggested that the presence of mutations in all three loci increases the risk for elevated IgE up to fourfold. CONCLUSION: This fine-mapping study confirmed previous associations and identified novel associations of SNPs in 1q23, 5q31, and 12q13 with different levels of serum IgE and their concomitant contribution to IgE regulation.

Solitary tuberculous brain lesions: 24 new cases and a review of the literature.

A solitary tuberculous brain lesion (STBL) can be difficult to distinguish from a glioma, metastasis or other infectious disease, especially from a pyogenic brain abscess. We analyzed the clinical characteristics, diagnostic procedures and outcomes of 24 patients with STBL diagnosed in three centers from France, India and Mexico. We also reviewed 92 STBL cases previously reported in the literature. General symptoms were found in 54% of our patients, including enlarged lymph nodes in 20%. Cerebrospinal fluid was typically abnormal, with lymphocytic pleocytosis and a high protein level. The lung CT scan was abnormal in 56% of patients, showing lymphadenopathy or pachipleuritis. Brain MRI or CT was always abnormal, showing contrast-enhanced lesions. Typically, MRI abnormalities were hypointense on T1-weighted sequences, while T2-weighted sequences showed both a peripheral hypersignal and a central hyposignal. The diagnosis was documented microbiologically or supported histologically in 71% of cases. Clinical outcome was good in 83% of cases.

A role of FCER1A and FCER2 polymorphisms in IgE regulation.

BACKGROUND: Both FCER2 and FCER1A encode subunits of IgE receptors. Variants in FCER1A were previously identified as major determinants of IgE levels in genome-wide association studies. METHODS: Here we investigated in detail whether FCER2 polymorphisms affect IgE levels alone and/or by interaction with FCER1A polymorphisms. To cover the genetic information of FCER2, 21 single-nucleotide polymorphisms (SNPs) were genotyped by Illumina HumanHap300 BeadChip (5 SNPs) and the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS; 14 SNPs) in at least 1303 Caucasian children (651 asthmatics) (ISAAC II/ MAGICS population); genotypes of two SNPs were imputed. RESULTS: SNP rs3760687 showed the most consistent effect on total serum IgE levels (b [SE] = -0.38 [0.16]; P = 0.016), while FCER2 polymorphisms in general were predominantly associated with mildly-to-moderately increased IgE levels (50th and 66th percentiles). Gene-by-gene interaction analysis suggests that FCER2 polymorphism rs3760687 influences IgE levels mainly in individuals not homozygous for the risk allele of FCER1A polymorphism rs2427837, which belongs to the major IgE-determining tagging bin in the population. CONCLUSION: FCER2 polymorphism rs3760687 affects moderately elevated total serum IgE levels, especially in the absence of homozygosity for the risk allele of FCER1A SNP rs2427837.

Polymorphisms in the IRF-4 gene, asthma and recurrent bronchitis in children.

BACKGROUND: Interferon-regulatory factors (IRFs) play a crucial role in immunity, not only influencing interferon expression but also T cell differentiation. IRF-4 was only recently recognized as a further major player in T cell differentiation. OBJECTIVE: As IRF-1 polymorphisms were shown to be associated with atopy and allergy, we comprehensively investigated effects of IRF-4 variants on allergy, asthma and related phenotypes in German children. METHODS: Fifteen tagging single nucleotide polymorphisms (SNPs) in the IRF-4 gene were genotyped by MALDI-TOF MS in the cross-sectional ISAAC phase II study population from Munich and Dresden (age 9-11; N = 3099). Replication was performed in our previously established genome-wide association study (GWAS) data set (N = 1303) consisting of asthma cases from the Multicenter Asthma Genetic in Childhood (MAGIC) study and reference children from the ISAAC II study. RESULTS: SNPs were not significantly associated with asthma but with bronchial hyperresponsiveness, atopy and, most interestingly, with recurrent bronchitis in the first data set. The IRF-4 variant rs9378805 was associated with recurrent bronchitis in the ISAAC population and replicated in the GWAS data set where further SNPs showed associations with recurrent bronchitis and asthma. CONCLUSIONS: We found genetic associations in IRF-4 to be associated with recurrent bronchitis in our two study populations. Associated polymorphisms are localized in a putative regulatory element in the 3'UTR region of IRF-4. These findings suggest a putative role of IRF-4 in the development of bronchitis.

Genome-wide association study of body mass index in 23 000 individuals with and without asthma.

BACKGROUND: Both asthma and obesity are complex disorders that are influenced by environmental and genetic factors. Shared genetic factors between asthma and obesity have been proposed to partly explain epidemiological findings of co-morbidity between these conditions. OBJECTIVE: To identify genetic variants that are associated with body mass index (BMI) in asthmatic children and adults, and to evaluate if there are differences between the genetics of BMI in asthmatics and healthy individuals. METHODS: In total, 19 studies contributed with genome-wide analysis study (GWAS) data from more than 23 000 individuals with predominantly European descent, of whom 8165 are asthmatics. RESULTS: We report associations between several DENND1B variants (P = 2.2 × 10(-7) for rs4915551) on chromosome 1q31 and BMI from a meta-analysis of GWAS data using 2691 asthmatic children (screening data). The top DENND1B single nucleotide polymorphisms(SNPs) were next evaluated in seven independent replication data sets comprising 2014 asthmatics, and rs4915551 was nominally replicated (P < 0.05) in two of the seven studies and of borderline significance in one (P = 0.059). However, strong evidence of effect heterogeneity was observed and overall, the association between rs4915551 and BMI was not significant in the total replication data set, P = 0.71. Using a random effects model, BMI was overall estimated to increase by 0.30 kg/m(2) (P = 0.01 for combined screening and replication data sets, N = 4705) per additional G allele of this DENND1BSNP. FTO was confirmed as an important gene for adult and childhood BMI regardless of asthma status. CONCLUSIONS AND CLINICAL RELEVANCE: DENND1B was recently identified as an asthma susceptibility gene in a GWAS on children, and here, we find evidence that DENND1B variants may also be associated with BMI in asthmatic children. However, the association was overall not replicated in the independent data sets and the heterogeneous effect of DENND1B points to complex associations with the studied diseases that deserve further study.

Direct inhibition of factor VIIa by TFPI and TFPI constructs.

BACKGROUND: Tissue factor pathway inhibitor (TFPI) is a multi-Kunitz domain protease inhibitor that down-regulates the extrinsic coagulation pathway by inhibiting FXa and FVIIa. OBJECTIVES: To investigate the role of the three Kunitz domains (KDs) of TFPI in FVIIa inhibition using full-length TFPI (TFPIfl ) and truncated TFPI constructs. METHODS: Inhibition of FVIIa with/without relipidated tissue factor (TF) or soluble TF (sTF) by TFPIfl /TFPI constructs was quantified with a FVIIa-specific chromogenic substrate. RESULTS AND CONCLUSIONS: TFPIfl inhibited TF-FVIIa via a monophasic reaction, which is rather slow at low TFPIfl concentrations (t½  ≈ 5 min at 2 nm TFPI) and has a Ki of 4.6 nm. In the presence of sTF and without TF, TFPIfl was a poor FVIIa inhibitor, with Ki values of 122 nm and 1118 nm, respectively. This indicates that phospholipids and TF significantly contribute to FVIIa inhibition by TFPIfl . TFPI constructs without the KD3-c-terminus (TFPI1-150 and KD1-KD2) were 7-10-fold less effective than TFPIfl in inhibiting TF-FVIIa and sTF-FVIIa, indicating that the KD3-C-terminus significantly contributes to direct inhibition of FVIIa by TFPI. Compared with KD1-KD2, KD1 was a poor TF-FVIIa inhibitor (Ki =434 nm), which shows that the KD2 domain of TFPI also contributes to FVIIa inhibition. Protein S stimulated TF-FVIIa inhibition by TFPIfl (Ki =0.7 nm). In the presence of FXa, a tight quaternary TF-FVIIa-TFPI-FXa complex is formed with TFPIfl , TFPI1-150 and KD1-KD2, with Ki values of < 0.15 nm, 0.5 nm and 0.8 nm, respectively, indicating the KD3-C-terminus is not a prerequisite for quaternary complex formation. Phospholipids and the Gla-domain of FXa are required for quaternary complex formation.

Endocavitary contrast enhanced ultrasound (CEUS)--work in progress.

PURPOSE: To demonstrate the benefit concerning localisation, measurement and visualisation of complications of drained fluid collections in the abdomen by applying ultrasound contrast agent via drainage catheters. In addition, to investigate the usefulness of CEUS in applying the agents in the biliary tract or when given orally. MATERIALS AND METHODS: A single drop of SonoVue® was added to 0.9 % saline solution and instilled via drainage catheters. Location, dimensions and complications of drained fluid collections were recorded and compared to the results of sonographic examination using saline solution alone and fluoroscopic examination using iodinated contrast agents. The biliary system was visualised by applying the solution via nasobiliary drains or via ERC catheterisation. Orally administered solutions consisted of one drop of SonoVue® in 50 ml aqua. RESULTS: Admixture of an ultrasound contrast agent to saline solution facilitates position monitoring of the drains in fluid collections and provides reliable information on the dimensions of the drained collection. Complications like fistulae to the biliary system, blood vessels, small or large intestine or to the peritoneal cavity are precisely displayed. The biliary system is shown in detailed description. Orally administered, the contrast agent is visible after intake long unto the colon. Insufficient anastomoses or spontaneous perforations become detectable. CONCLUSION: The application of ultrasound contrast agents via drainage catheters provides substantial information on location and dimensions of drained fluid collections and their communication with surrounding organ structures. The biliary system can be visualised. Oral administration is feasible and provides important additional information.

Polymorphisms of interleukin 18 in the genetics of preterm birth and bronchopulmonary dysplasia.

Interleukin 18 (IL-18) is an important cytokine and involved in the pathogenesis and genetics of many diseases. The authors studied two different populations of preterm infants to test whether polymorphisms within IL-18 are in association with prematurity itself or with typical pulmonary disease or measurements seen in preterm infants, such as bronchopulmonary dysplasia, pneumothoraces and application of surfactant, inhalation or mechanical ventilation. Whereas the first population of 228 preterm infants showed strong association of IL-18 with preterm birth (p<0.001), this was not confirmed in the second population of 346 preterm infants. In addition, no association with any lung condition of prematurity was observed. The authors conclude that IL-18 does not play an important role in the genetics of preterm birth nor in the development of bronchopulmonary dysplasia and other lung complications in preterm infants. Caution must be taken in the interpretation of the results of genetic association studies performed in one population.

Sulphidoleukotriene release of cord blood basophils in response to allergen stimulation correlates with neither a family history of atopy nor a subsequent development of atopic eczema.

OBJECTIVE: We tested a possible relationship between sulphidoleukotriene (SLT) release of cord blood (CB) basophils, a family history of atopy (HA) and subsequent development of atopic eczema. Population and methods A cohort of 86 neonates were involved (48.8% males; 46.5% with a positive HA(+)). CB samples were analysed for in vitro SLT release quantified by ELISA, and in a subgroup for basophilic activation (CD 63 expression) by flow cytometry in response to a positive control (anti-IgE-receptor antibody), an allergen-mix (TOP and PTOP), egg white (EW), egg yolk (EY), and the purified allergens beta-lactoglobulin (BLG) and alpha-lactalbumin (ALA). RESULTS: Median concentrations of SLT were 124.2 (negative), 3871.5 (positive), 123.9 (TOP), 128.5 (PTOP), 113.1 (EW), 108.4 (EY), 125.2 (BLG) and 122.3 (ALA) pg/mL. Groups of HA(+) and HA(-) show no difference in all analysed allergens. An allergen-specific SLT release (defined as SLT>125 pg/mL above individual baseline and a stimulation index >2) was detected in 98% (positive control), 5% (TOP), 7% (BLG), 3% (ALA) and 2% (EW and EY), respectively. After a median observation period of 18 months, n=7 out of 70 children developed an atopic eczema, but we observed no association between CB SLT release (positive response to at least one tested allergen). CONCLUSION: Allergen-specific SLT release is detectable in 15.5% of healthy neonates, irrespective of their family history of atopy. However, early allergen-specific SLT release is not predictive for the development of atopy.

Lactobacillus GG has in vitro effects on enhanced interleukin-10 and interferon-gamma release of mononuclear cells but no in vivo effects in supplemented mothers and their neonates.

BACKGROUND: The value of probiotics for primary prevention is controversial. Moreover, only little is known about the underlying immunological mechanisms of action. Therefore, we assessed the proliferative response and cytokine release in cultures of isolated mononuclear cells from pregnant women and their neonates supplemented with Lactobacillus GG (LGG) or placebo. METHODS: In a double-blind, placebo-controlled prospective trial, pregnant women with at least one first-degree relative or a partner with an atopic disease were randomly assigned to receive either the probiotic LGG (ATCC 53103; 5 x 10(9) colony-forming units LGG twice daily) or placebo 4-6 weeks before expected delivery, followed by a post-natal period of 6 months. Cord blood mononuclear cells (CBMC) and peripheral blood mononuclear cells (PBMC) of the corresponding mother were isolated from cord blood and peripheral blood (n=68). The proliferative response of CBMC and PBMC was expressed as the stimulation index (SI), which was calculated according to the ratio between the mean counts per minute (c.p.m.) values measured in the wells with stimulated cells and the mean c.p.m. values measured in the wells with unstimulated cells. Additionally, the cytokines IFN-gamma, IL-10 and IL-13 in the cell culture supernatants were measured using the ELISA technique. RESULTS: No difference was observed between the LGG-supplemented group and the placebo group in terms of the proliferative capacity of maternal or neonatal cord blood cells in response to IL-2, beta-lactoglobulin or LGG. In vitro stimulation with LGG resulted in significantly enhanced release of IL-10 and IFN-gamma, compared with cytokine release in unstimulated controls. However, this phenomenon was observed in supernatants of maternal and neonatal MC in both groups, independent of prior supplementation with LGG. CONCLUSION: LGG has in vitro effects on enhanced IL-10 and IFN-gamma release of mononuclear cells. However, supplementation with LGG during pregnancy did not alter the proliferative capacity or cytokine pattern in their recipients.

Genetic polymorphisms of adhesion molecules in children with severe RSV-associated diseases.

Adhesion molecules are involved in the pathophysiology of respiratory syncytial virus (RSV)-associated diseases. By testing polymorphisms within ICAM-1, VCAM-1 and E-selectin, we found no evidence for association of any polymorphism with severe RSV infections. Thus, we conclude that these genes do not predispose to severe RSV-associated diseases.

A comprehensive candidate gene study on bronchial asthma and juvenile idiopathic arthritis.

Bronchial asthma and juvenile idiopathic arthritis (JIA) are complex genetic diseases. As both represent chronic inflammatory diseases it is likely that they are at least partially influenced by the same genetic variants. One goal in dissecting the genetics of complex diseases is to identify a genetic risk profile. Therefore it is necessary to genotype polymorphisms in many different pathways. Thus we investigated 48 polymorphisms in 24 genes for association with asthma and/or JIA. Genotpying was performed on 231 asthmatic children, 86 children with JIA and 270 controls. Association analysis was performed by the Armitage's trend test. Furthermore haplotypes were calculated by FAMHAP. We found association of polymorphisms within IL-4, CTLA4 and TNFalpha with asthma and/or JIA. Furthermore, the polymorphisms showed an inverse distribution between children with asthma and JIA. However, we were not able to confirm association of most of the previously described candidate genes. We conclude from our data that it might be very difficult to identify genetic risk profiles for the development of asthma and/or JIA that would be valid across different populations. However, this study adds further evidence that the common genetic background of asthma and JIA is mainly based on polymorphisms in important TH1 and TH2 cytokines.

Genetic polymorphisms of chitotriosidase in Caucasian children with bronchial asthma.

In humans, two types of chitinases have been identified: chitotriosidase I (CHIT1) and acid mammalian chitinase (AMCase). They are enzymes that cleave chitin, a polysaccharide contained in many different human parasites. So far, only little is known about their function in human and especially in human diseases. Recently we have described association of polymorphisms of AMCase with bronchial asthma in a pediatric population. In this study we were interested in whether CHIT1 is also involved in the genetics of asthma. The amino acid variants Gly102Ser and Ala442Gly, as well as a 24 bp duplication within CHIT1, were typed by means of restriction fragment length polymorphisms on 322 children with asthma and 270 randomly chosen adult controls. Statistical analyses made use of the Armitage's trend test; haplotypes were calculated by FAMHAP and FASTEHPLUS. The amino acid variants showed no association with bronchial asthma. The 24 bp duplication, previously shown to completely demolish CHIT1 activity, was also evenly distributed between asthmatics and controls. Finally, the haplotype showed no association with the disease. We conclude from our results that CHIT1 does not play a major role in the development of bronchial asthma in Caucasian children. The results might also imply that the two human chitinases that have been identified so far have quite distinct functions in human diseases even though they have the same substrate.