Lucas André Cavalcanti Brandão

Two SNPs in NLRP3 gene are involved in the predisposition to type-1 diabetes and celiac disease in a pediatric population from northeast Brazil

Recent findings provide evidence of the critical role of innate immunity NALP1/NLRP1 and NALP3/NLRP3/CIAS1 genes in inflammatory diseases, and also in the predisposition to autoimmune disorders. We evaluated the possible association of five single nucleotide polymorphisms (SNPs), two in NLRP1 gene and three in NLRP3 gene, in pediatric patients from the north eastern region of Brazil affected by type-1 diabetes (T1D, n = 196), celiac disease (CD, n = 59), and atopic dermatitis (AD, n = 165), and in healthy individuals (n = 192). Our results demonstrated that NLRP3 rs10754558 SNP was associated specifically to T1D (p = 4exp-3) and NLRP3 rs358294199 SNP to CD (p = 5exp-4) in the Brazilian population. Despite its strong association with T1D in Norwegian population, NLRP1 was not associated with T1D, in the Brazilian population. According to previous studies in Caucasoid cohorts, NLRP1 and NLRP3 seemed not to be associated to AD. Since it has been reported that IL-1beta has a systemic effect in the lost of the immunologic tolerance and that NALP3 inflammasome is directly involved in the production of this pro-inflammatory cytokine, we hypothesized that variations in NLRP3 could belong to a predisposing genetic background that contribute to the development of autoimmune diseases.

Prevalence of autoimmune thyroid disease and thyroid dysfunction in young Brazilian patients with type 1 diabetes.

Abstract:  Patients with an autoimmune condition are known to be at higher risk of developing other autoimmune disorders. Type 1 diabetes may be associated with additional autoimmune disorders including autoimmune thyroid disease. The aim of this study was to investigate the prevalence of thyroid autoantibodies in a group of children, adolescents, and young adults with type 1 diabetes from northeastern Brazil as well as their significance for the development of thyroid disorders. The study design was cross‐sectional and descriptive, analyzing young people with a previous type 1 diabetes diagnosis. Two hundred and fourteen children and adolescents with prior diagnosis of type 1 diabetes were evaluated. Antibodies to thyroperoxidase (anti‐TPO) were determined in all patients and thyroid‐stimulating hormone (TSH) levels. The anti‐TPO antibody test was positive in 54 out of the 214 patients studied, resulting in an overall prevalence of 25.2%. Among the anti‐TPO‐positive subjects, females were predominant (72%) over males (28%) (p < 0.001). A total of 55.5% patients with positive anti‐TPO antibodies had abnormal TSH levels. Clinically significant hypothyroidism was found in 29.6% and subclinical hypothyroidism in 22.2% of patients with positive anti‐TPO. Hyperthyroidism was present in only 3% of them. Our results demonstrate the high prevalence of autoimmune thyroiditis in patients with type 1 diabetes and the need for these patients of regular screening to make a precocious diagnosis of thyroid dysfunction.

Meta-analysis of Brazilian genetic admixture and comparison with other Latin America countries.

This study aims at performing a systematic review and meta‐analysis with the studies of genetic admixture inference of Brazilian population and to compare these results with the genetic admixture levels in other Latin American countries.

Mannose binding lectin gene (MBL2) functional polymorphisms are associated with systemic lupus erythematosus in southern Brazilians

Susceptibility to systemic lupus erythematosus (SLE) has been associated with immunologic, environmental, and genetic factors. To uncover a possible association between MBL2 gene polymorphisms and SLE, we analyzed functional polymorphisms in the promoter and first exon of the MBL2 gene in 134 Brazilian SLE patients and 101 healthy controls. Genotype and allele frequencies of MBL2 A/O polymorphism were significantly different between patients and controls, and the O allele was associated with an increased risk of SLE. An association between low mannose binding lectin (MBL) producer combined genotypes and increased risk for SLE was also reported. Furthermore, when stratifying SLE patients according to clinical and laboratory data, an association between the A/O genotype and nephritic disorders and between the X/Y genotype and antiphospholipid syndrome was evident. Combined genotypes responsible for low MBL production were more frequently observed in SLE patients with nephritis. Our results indicate MBL2 polymorphisms as possible risk factors for SLE development and disease-related clinical manifestations.

Principles and applications of polymerase chain reaction in medical diagnostic fields: a review

Recent developments in molecular methods have revolutionized the detection and characterization of microorganisms in a broad range of medical diagnostic fields, including virology, mycology, parasitology, microbiology and dentistry. Among these methods, Polymerase Chain Reaction (PCR) has generated great benefits and allowed scientific advancements. PCR is an excellent technique for the rapid detection of pathogens, including those difficult to culture. Along with conventional PCR techniques, Real-Time PCR has emerged as a technological innovation and is playing an ever-increasing role in clinical diagnostics and research laboratories. Due to its capacity to generate both qualitative and quantitative results, Real-Time PCR is considered a fast and accurate platform. The aim of the present literature review is to explore the clinical usefulness and potential of both conventional PCR and Real-Time PCR assays in diverse medical fields, addressing its main uses and advances.

Association between MBL2 gene functional polymorphisms and high-risk human papillomavirus infection in Brazilian women

We studied the association between high-risk human papillomavirus (HPV) infection and MBL2 functional polymorphisms in a group of 180 high-risk HPV-infected women and 180 healthy control subjects. The most frequent high-risk HPV genotypes were 16 (47.2%), 31 (11.7%), 33 (5%), and 18 (2.2%), respectively. Of the 180 HPV-infected women, 99 presented with uterine cervical cancer and 81 did not. No differences in MBL2 genotype or in allelic or haplotype frequencies were found between HPV patients who developed cervical uterine cancer and those who did not. When considering combined genotypes grouped according to MBL production (designated as high, low, and deficient producers), we detected a significant difference between healthy controls and high-risk HPV-positive patients, the latter group showing increased frequencies of deficient-producer genotypes (14.4% vs 9.4% in the healthy control group, corrected p = 0.04). In conclusion, a correlation between MBL2 polymorphisms and high-risk HPV infection was found in this study.

MBL2 gene polymorphisms and susceptibility to tuberculosis in a northeastern Brazilian population

The innate immune system represents the first line of host defense against pathogens. Genetics factors regulating the immune responses play a role in the susceptibility to infectious diseases, such as tuberculosis (TB). We analyzed MBL2 promoter and exon 1 functional single nucleotide polymorphisms (SNPs) in a group of 155TB patients and 148 healthy controls in order to evaluate their influence on the onset of infection and TB development. There was no association between MBL2 -550 HL promoter polymorphisms and susceptibility to develop TB, but heterozygous -221 Y/X genotype was significantly more frequent in pulmonary TB patients than controls. Moreover, MBL2 exon 1 O allele, was significantly associated with susceptibility to TB development in general (p=0.023, OR=1.61, 95% CI 1.05-2.49) and pulmonary TB (p=0.0008, OR=2.16, 95% CI 1.35-3.46); C allele at codon 57, as well as A/C genotype, were significantly more frequent in TB patients than in controls. Our results indicate that MBL2 polymorphisms, especially at codon 57, could be considered as risk factors for TB development.

The role of mannose-binding lectin gene polymorphisms in susceptibility to HIV-1 infection in Southern Brazilian patients.

Objective:This study investigates the role of mannose-binding lectin (MBL) in the susceptibility to HIV-1 infection analyzing polymorphisms located at the MBL2 promoter and exon 1 regions. Materials and methods:The prevalence of MBL2 variant alleles was investigated in 410 HIV-1-infected patients from the South Brazilian HIV cohort and in 345 unexposed uninfected healthy individuals. The promoter variants were genotyped using polymerase chain reaction with sequence-specific primers (PCR-SSP) and exon 1 variants were analyzed by real-time PCR using a melting temperature assay and were confirmed by PCR-restriction fragment length polymorphism (RFLP). MBL2 genotypic and allelic frequencies were compared between HIV-1-infected patients and controls using the chi-squared tests. Results:The analyses were performed subdividing the individuals according to their ethnic origin. Among Euro-derived individuals a higher frequency of the LX/LX genotype was observed in patients when compared to controls (P < 0.001). The haplotypic analysis also showed a higher frequency of the haplotypes associated with lower MBL levels among HIV-1-infected patients (P = 0.0001). Among Afro-derived individuals the frequencies of LY/LY and HY/HY genotypes were higher in patients when compared to controls (P = 0.009 and P = 0.02). Conclusions:An increased frequency of MBL2 genotypes associated with low MBL levels was observed in Euro-derived patients, suggesting a potential role for MBL in the susceptibility to HIV-1 infection in Euro-derived individuals.

NLRP3 polymorphism is associated with protection against human T-lymphotropic virus 1 infection

Inter-individual heterogeneity in the response to human T-lymphotropic virus 1 (HTLV-1) infection has been partially attributed to host genetic background. The antiviral activity of the inflammasome cytoplasmic complex recognises viral molecular patterns and regulates immune responses via the activation of interleukin (IL)-1 family (IL-1, IL-18 and IL-33) members. The association between polymorphisms in the inflammasome receptors NLRP1 and NLRP3 and HTLV-1 infection was evaluated in a northeastern Brazilian population (84 HTLV-1 carriers and 155 healthy controls). NLRP3 rs10754558 G/G was associated with protection against HTLV-1 infection (p = 0.012; odds ratio = 0.37). rs10754558 affects NLRP3 mRNA stability; therefore, our results suggest that higher NLRP3 expression may augment first-line defences, leading to the effective protection against HTLV-1 infection.

Interleukin 18 (IL18) gene promoter polymorphisms are associated with type 1 diabetes mellitus in Brazilian patients

Interleukin 18 (IL-18) is a cytokine that plays an important role in the Th1 response, by its ability to induce IFN-γ production in T cells and natural killer cells. Functional variants of IL18 gene has been reported as associated with type 1 diabetes (T1D). In the present study were analyzed three promoter single nucleotide polymorphisms (SNPs), at -656 (rs1946519), -607 (rs1946518) and -137 (rs187238) position, in 181 children and adolescents with T1D and 122 healthy individuals, both from metropolitan area of Recife, Northeast of Brazil. T1D patients were stratified according to the presence autoimmune thyroiditis and celiac disease. Allele and genotype frequencies of IL18 SNPs were Hardy-Weinberg equilibrium in patients and controls. The allele -137G and the haplotype -656G/-607C/-137G were more frequent in T1D patients (OR=1.82 and 1.97, respectively) then in healthy controls. However, those SNPs were not associated with the age of T1D onset as well as with the insurgence of AITD and/or CD in concomitant with T1D patients. Our findings suggest an association between IL18 promoter SNPs and susceptibility to T1D in Brazilian patients.