Interaction between smoking and HLA-DRB1*04 gene is associated with a high cardiovascular risk in Brazilian Amazon patients with rheumatoid arthritis

Background: Rheumatoid Arthritis (RA) is an autoimmune disease characterized by chronic inflammation of the joints that affects approximately 1% of the population worldwide. The HLA-DRB1 gene locus plays a major role in genetic susceptibility to RA, a condition that has been associated with a high cardiovascular morbidity and mortality in many studies. Methodology/Principal Findings: The aim of this work was to investigate which types of HLA class II genes are associated with RA in patients from the Brazilian Amazon and their influence on high cardiovascular risk status in this population. For this purpose, a case-control study was carried out with a total of 350 non-Indian individuals made up of a cohort of 132 consecutive RA sufferers and 218 healthy controls. A χ2 test showed that HLADRB1*04 (p<0.0016; OR = 1.89; 95% CI = 1.29-2.79) and HLADRB1*10 (p = 0.0377; OR = 3.81; 95% CI = 1.16-12.50) are the major HLA genes associated with susceptibility to RA. A logistic regression model also showed that the interaction between HLADRB1*04 (p = 0.027; OR = 6.02; 95% CI = 1.21-29.7), age (p = 0.0001; OR = 1.26; 95% CI = 1.13-1.39) and smoking (p = 0.0001; OR = 23.6; 95% CI = 4.25-32.1) is associated with a probability of a high cardiovascular risk status at an early age. Conclusions/Significance: The results of this study show for the first time that HLA class II type is associated with RA in Brazilian Amazon populations and that a specific interaction between the HLA-DRB1*04 gene and smoking is associated with a high cardiovascular risk status, as initially reported in the European population. This study therefore contributes to an understanding of gene-environment interactions in RA patients. © 2012 Boechat et al

PCR in the diagnosis of cutaneous tuberculosis

Seeking to improve the laboratory diagnosis of Cutaneous Tuberculosis, a study was carried out on the application of PCR technique in macerated, decontaminated (with 4% H2SO4 for elimination of normal microbiot), neutralized (with 4% NaOH) biopsies tissues samples stored at -20°C. Of the 37 samples submitted for study, 16.22% were positive by microscopy for acid-fast bacilli (concentrated method) and in 43.24% the Mycobacterium tuberculosis was isolated in Löwenstein-Jensen medium. Using a M. tuberculosis complex specific primer set (gene sequence for 16S rDNA), the mycobacterial DNA was detected in 24.32% of the biopsies. The sensitivity and specificity of PCR were 43.7% and 90.4%, respectively. Due to low sensitivity and discrepant results between bacteriological techniques and PCR methodology, the samples were repeated in a new PCR with primers for the IS6110 target. The sensitivity and specificity of PCR for the IS6110 target obtained 100% in comparison with the culture method. The results confirm the effectiveness of PCR methodology using primers for the IS6110 gene sequence and permit the PCR method to be applied to frozen cutaneous biopsies sent by services that do not identify the M. tuberculosis by the biology molecular method

HLA in Brazilian Ashkenazic Jews with chronic dermatophytosis caused by Trichophyton rubrum

The frequency of HLA (Human Leucocyte Antigens) was analyzed in 25 non-consanguineous Brazilian Ashkenazic Jews, resident in the city of São Paulo, Brazil, suffering from chronic dermatophytosis caused by T. rubrum, and in 25 non-infected individuals belonging to the same ethnic group. Statistically significant values (p<0.05) were observed for HLA-B14 associated with resistance to chronic dermatophytosis and HLA-DQB1*06 (p=0.05) possibly related to susceptibility. These findings suggest that genes on the chromosome 6, in the region of the major histocompatibility complex, may influence the development of chronic dermatophytosis