Accuracy of serologic tests and HLA-DQ typing for diagnosing celiac disease.

BACKGROUND: Estimates of the diagnostic performance of serologic testing and HLA-DQ typing for detecting celiac disease have mainly come from case-control studies. OBJECTIVE: To define the performance of serologic testing and HLA-DQ typing prospectively. DESIGN: Prospective cohort study. SETTING: University hospital. PATIENTS: Patients referred for small-bowel biopsy for the diagnosis of celiac disease. INTERVENTIONS: Celiac serologic testing (antigliadin antibodies [AGA], antitransglutaminase antibodies [TGA], and antiendomysium antibodies [EMA]) and HLA-DQ typing. MEASUREMENTS: Diagnostic performance of serologic testing and HLA-DQ typing compared with a reference standard of abnormal histologic findings and clinical resolution after a gluten-free diet. RESULTS: Sixteen of 463 participants had celiac disease (prevalence, 3.46% [95% CI, 1.99% to 5.55%]). A positive result on both TGA and EMA testing had a sensitivity of 81% (CI, 54% to 95.9%), specificity of 99.3% (CI, 98.0% to 99.9%), and negative predictive value of 99.3% (CI, 98.0% to 99.9%). Testing positive for either HLA-DQ type maximized sensitivity (100% [CI, 79% to 100%]) and negative predictive value (100% [CI, 98.6% to 100%]), whereas testing negative for both minimized the negative likelihood ratio (0.00 [CI, 0.00 to 0.40]) and posttest probability (0% [CI, 0% to 1.4%]). The addition of HLA-DQ typing to TGA and EMA testing, and the addition of serologic testing to HLA-DQ typing, did not change test performance compared with either testing strategy alone. LIMITATION: Few cases of celiac disease precluded meaningful comparisons of testing strategies. CONCLUSIONS: In a patient population referred for symptoms and signs of celiac disease with a prevalence of celiac disease of 3.46%, TGA and EMA testing were the most sensitive serum antibody tests and a negative HLA-DQ type excluded the diagnosis. However, the addition of HLA-DQ typing to TGA and EMA testing, and the addition of serologic testing to HLA-DQ typing, provided the same measures of test performance as either testing strategy alone.

Clinical applications of NOD2/CARD15 mutations in Crohn's disease.

The recent identification of the CARD15/NOD2 gene as a susceptibility locus for Crohn's disease represents an important step in the immunopathogenesis of inflammatory bowel disease. The gene explains about 20% of the genetic susceptibility CARD15 mutations are present in 30-50% of CD patients compared to 7-20% of healthy controls. The three risk alleles R702W, G908R and 1007fsInsC in NOD2 associated with susceptibility to Crohn's disease have demonstrated a remarkable amount of heterogeneity across ethnicities and populations, with regional variation across Europe. In non-Caucasian populations Crohn's disease continues to increase in incidence but this increase appears not to be a consequence of variation in NOD2. Genotype-phenotype analyses demonstrated an association of these mutations with ileum-specific disease and an increased incidence of the fibrostenotic phenotype. Although CARD15 variants do not predict response to the TNF alpha monoclonal antibodies, there are no data available on the possible influence of CARD15 mutations on response to other drugs. Screening for CARD15 mutations in order to identify high-risk individuals or to introduce an individualized disease management is therefore currently not recommended.

MDR1 polymorphisms and response to azathioprine therapy in patients with Crohn's disease.

BACKGROUND: To investigate the contribution of multidrug resistance 1 (MDR1) gene pharmacogenetics (G2677T/A and C3435T) to the efficacy of azathioprine in inducing remission in patients with Crohn's disease (CD). METHODS: A cohort of 327 unrelated Spanish patients with CD recruited from a single center was studied. All patients were rigorously followed up for at least 2 years (mean time, 11.5 years). A case-control analysis of MDR1 G2677T/A and C3435T SNPs and 2 loci haplotypes in 112 steroid-dependent CD patients treated with azathioprine was performed. Patients were classified on the basis of response to azathioprine. RESULTS: A total 76 patients treated with azathioprine for longer than 3 months were included. Remission was achieved in 42 CD patients (55.3%). A higher frequency of the 2677TT genotype was found in nonresponders than in responders (17.65% versus 7.14%; OR = 2.8; 95% CI; 0.6-12.1; P = 0.11). Nonresponders to azathioprine were found to have a higher frequency of the 3435TT genotype than did CD patients who had achieved clinical remission (17.64% versus 4.76%; OR = 4.3; 95% CI, 0.8-22.8; P = 0.06). The 2677T/3435T haplotype was also more abundant in nonresponders (29.4% versus 20.2%), whereas the 2677G/3435C haplotype was more frequent in responders (58.3% versus 47.1%). Lack of response to azathioprine therapy in CD patients was 1.8-fold greater in carriers of the 2677T/3435T haplotype than in carriers of the 2677G/3435C haplotype (OR = 1.8; 95% CI, 0.82-3.9; P = 0.14). CONCLUSIONS: The results of our study indicate higher frequencies of the 2677TT and 3435TT genotypes and the 2677T/3435T haplotype in CD patients who did not respond to azathioprine. Additional replications in independent populations would confirm the real impact of these polymorphisms in response to azathioprine therapy.

Synergistic effect of Toll-like receptor 4 and CD14 polymorphisms on the total atherosclerosis burden in patients with peripheral arterial disease.

BACKGROUND: Genes involved in the regulation of immune responses, such as Toll-like receptor 4 (TLR4) and CD14, show genetic variations with potential functional implications. Because atherosclerosis is an inflammatory process apparently modulated by chronic infections, we studied the effect of single nucleotide polymorphisms (SNPs) in TLR4 and CD14 on the extent of clinically relevant atherosclerosis in patients with peripheral arterial disease (PAD). METHODS: Using an in-house-developed polymerase chain reaction-based restriction length polymorphism assay, we determined the genotype, allele frequency, and carrier traits of the TLR4 +896 A>G and the CD14 -260 C>T SNPs in 607 white Dutch patients with PAD. The extent of clinically relevant atherosclerosis was determined on the basis of the number of vascular territories involved, ie, coronary, cerebral, aortic, and peripheral. RESULTS: A total of 55% of the patients had PAD only. Approximately one third of the patients had two and 11% had three vascular territories affected by clinically relevant atherosclerosis. The TLR4 +866 G allele frequency was 11%, and the CD14 -260 T allele frequency was approximately 74%. Among PAD patients, TLR4 +896 G allele carriership was univariantly associated with extensive (more than two vascular territories affected) atherosclerotic disease (odds ratio, 2.22; P = .020; chi(2) test), whereas CD14 -260 C>T carriership/homozygosity was not. Trend analysis showed that the TLR4 +866 G allele frequency increased with the number of vascular territories affected by clinically relevant atherosclerosis (P trend, .0074). In a multivariate logistic regression analysis including cardiovascular risk factors and TLR4 and CD14 SNPs, only the interaction variable "TLR4 +896 G allele carriership/CD14 -260 TT genotype" survived as an independent predictor of extensive atherosclerotic disease (P = .031; odds ratio, 4.2; 95% confidence interval, 1.1-15.4). CONCLUSIONS: The carrier trait TLR4 G allele/CD14 TT genotype, rather than each SNP individually, is associated with the extent of clinically relevant atherosclerotic disease. Considering the importance of immune responses in atherogenesis and the genetic variation of immune regulatory genes, our data provide an explanation for interindividual differences in susceptibility to atherosclerosis and demonstrate the need to take a wider approach in analyzing relevant carrier traits instead of individual polymorphisms in relation to atherosclerosis.

Comparison of multiple genital tract infections with Chlamydia trachomatis in different strains of female mice.

We have previously shown that female outbred CF-1 mice are susceptible to prolonged genital tract infection with the oculogenital serovars (D-K) of Chlamydia trachomatis, and that partial homotypic and heterotypic protection against reinfection is induced. To understand the possible role of inherent T-helper 1 (Th1)/Th2 polarity bias on both the course of infection and the level of acquired immunity induced by infection, 2 immunologically different and well-characterized inbred strains of mice, BALB/c and C57BL/6, were studied in this model. Groups of mice were inoculated intravaginally with C. trachomatis serovar D (Ct D) and monitored by culture to determine the duration of initial infection. Two months later, mice were reinfected, and monitored along with age- and condition-matched control groups. Plasma and vaginal secretions were collected for serologic analysis and specific delayed-type hypersensitivity was assessed by footpad swelling. Initial infection in C57BL/6 mice was comparable in duration to outbred CF-1 mice (median duration 42 versus 43.5 days), while BALB/c mice had a shorter median duration of initial infection (12 days). All strains had significantly shorter durations of infection following reinfection. BALB/c mice shed 4-10 times more inclusion-forming units (IFU) than both C57BL/6 and CF-1 mice on sample days during the first week of infection and all strains shed less IFU during reinfection. C57BL/6 and BALB/c mice had significantly lower anti-Ct D immunoglobulin G titers in both plasma and vaginal secretions than CF-1 mice following resolution of infection; the frequency of immunoglobulin A seropositive vaginal secretions was less in both inbred strains, being significantly less in the case of C57BL/6 mice. Qualitative analysis of the antigen specificity and isotype composition revealed differences among the mouse strains. All 3 strains had detectable levels of specific footpad swelling on day 14 of infection, whereas only BALB/c mice showed a significant response at 70 days post-infection. Significant differences between 2 strains of mice that differ in Th1/Th2 polarity bias were observed in: 1) the duration of infection; 2) the level of bacterial shedding during infection; and 3) the quantitative and qualitative cellular and humoral responses made in response to female genital tract infection with a human oculogenital isolate of C. trachomatis. In addition, a similar and significant level of partial acquired immunity to reinfection was observed in both strains, suggesting that inherent Th1/Th2 polarity bias present upon initial infection does not prevent the development of a protective immune response within the genital tract during infection with an oculogenital isolate of C. trachomatis.

Characteristics of clinical Helicobacter pylori strains from Ecuador.

In Ecuador, Helicobacter pylori infections are highly prevalent. A total of 42 H. pylori clinical isolates from 86 patients attending the outpatient clinic of the gastroenterology department of the university hospital of Guayaquil in Ecuador were characterized. Their susceptibility, and cagA and vacA status were determined. Resistance to metronidazole and clarithromycin was found in 80.9% and 9.5% of strains, respectively. Neither amoxicillin- nor tetracycline-resistant strains were found. The most prevalent genotype was the cagA(+), vacA s1b,m1 type. This genotype was associated with gastric cancer and peptic ulcer. Typing by random amplified polymorphic DNA showed no genetic relationship among the strains.