Association of MICA and HLA-B alleles with leprosy in two endemic populations in Brazil.

Leprosy is a prevalent disease in Brazil, which ranks as the country with the second highest number of cases in the world. The disease manifests in a spectrum of forms, and genetic differences in the host can help to elucidate the immunopathogenesis. For a better understanding of MICA association with leprosy, we performed a case-control and a family-based study in two endemic populations in Brazil. MICA and HLA-B alleles were evaluated in 409 leprosy patients and in 419 healthy contacts by PCR-SSOP-Luminex-based technology. In the familial study, analysis of 46 families was completed by direct sequencing of all exons and 3'/5'untranslated regions, using the Ilumina MiSeq platform. All data were collected between 2006 and 2009. Statistical analysis was performed using the Chi-square or Fisher's exact test together with a multivariate analysis. Family-based association was assessed by transmission disequilibrium test (TDT) software FBAT 2.0.4. We found associations between the haplotype MICA*002-HLA-B*35 with leprosy in both the per se and the multibacillary (MB) forms when compared to healthy contacts. The MICA allele *008 was associated with the clinical forms of paucibacillary (PB). Additionally, MICA*029 was associated with the clinical forms of MB. The association of MICA*029 allele (MICA-A4 variant) with the susceptibility to the MB form suggests this variant for the transmembrane domain of the MICA molecule may be a risk factor for leprosy. Two MICA and nine HLA-B variants were found associated with leprosy per se in the Colônia do Prata population. Linkage disequilibrium analysis revealed perfect linkage disequilibrium (LD) between HLA-B markers rs2596498 and rs2507992, and high LD (R2  = .92) between these and the marker rs2442718. This familial study demonstrates that MICA association signals are not independent from those observed for HLA-B. Our findings contribute the knowledge pool of the immunogenetics of Hansen's disease and reveals a new association of the MICA*029 allele.

HLA-DPB1 and HLA-C alleles are associated with leprosy in a Brazilian population.

Despite intense efforts, the number of new cases of leprosy has remained significantly high over the past 20 years. Host genetic background is strongly linked to the pathogenesis of this disease, which is caused by Mycobacterium leprae (M. leprae), and there is a consensus that the most significant genetic association with leprosy is attributed to the major histocompatibility complex (MHC). Here, we investigated the association of human leukocyte antigen (HLA) class I and II genes with leprosy in a Brazilian population encompassing 826 individuals from a hyperendemic area of Brazil; HLA typing of class I (-A, -B, -C) and class II (-DRB1, -DQA1, -DQB1, -DPA1, and -DPB1) loci was conducted. Initially, the associations were tested using the chi-square test, with p-values adjusted using the false discovery rate (FDR) method. Next, statistically significant signals of the associations were submitted to logistic regression analyses to adjust for sex and molecular ancestry data. The results showed that HLA-C*08, -DPB1*04, and -DPB1*18 were associated with protective effects, while HLA-C*12 and -DPB1*105 were associated with susceptibility to leprosy. Thus, our findings reveal new associations between leprosy and the HLA-DPB1 locus and confirm previous associations between the HLA-C locus and leprosy.

HLA-DPB1 and HLA-C alleles are associated with leprosy in a Brazilian population

Despite intense efforts, the number of new cases of leprosy has remained significantly high over the past 20 years. Host genetic background is strongly linked to the pathogenesis of this disease, which is caused by Mycobacterium leprae (M. leprae), and there is a consensus that the most significant genetic association with leprosy is attributed to the major histocompatibility complex (MHC). Here, we investigated the association of human leukocyte antigen (HLA) class I and II genes with leprosy in a Brazilian population encompassing 826 individuals from a hyperendemic area of Brazil; HLA typing of class I (-A, -B, -C) and class II (-DRB1, -DQA1, -DQB1, -DPA1, and -DPB1) loci was conducted. Initially, the associations were tested using the chi-square test, with p-values adjusted using the false discovery rate (FDR) method. Next, statistically significant signals of the associations were submitted to logistic regression analyses to adjust for sex and molecular ancestry data. The results showed that HLA-C*08, -DPB1*04, and -DPB1*18 were associated with protective effects, while HLA-C*12 and -DPB1*105 were associated with susceptibility to leprosy. Thus, our findings reveal new associations between leprosy and the HLA-DPB1 locus and confirm previous associations between the HLA-C locus and leprosy(AU).

Association of MICA and HLA­B alleles with leprosy in two endemic populations in Brazil

Leprosy is a prevalent disease in Brazil, which ranks as the country with the second highest number of cases in the world. The disease manifests in a spectrum of forms, and genetic differences in the host can help to elucidate the immunopathogenesis. For a better understanding of MICA association with leprosy, we performed a case­control and a family­based study in two endemic populations in Brazil. MICA and HLA­B alleles were evaluated in 409 leprosy patients and in 419 healthy contacts by PCR­SSOP­Luminex­based technology. In the familial study, analysis of 46 families was completed by direct sequencing of all exons and 3'/5'untranslated regions, using the Ilumina MiSeq platform. All data were collected between 2006 and 2009. Statistical analysis was performed using the Chi­square or Fisher's exact test together with a multivariate analysis. Family­based association was assessed by transmission disequilibrium test (TDT) software FBAT 2.0.4. We found associations between the haplotype MICA*002­HLA­B*35 with leprosy in both the per se and the multibacillary (MB) forms when compared to healthy contacts. The MICA allele *008 was associated with the clinical forms of paucibacillary (PB). Additionally, MICA*029 was associated with the clinical forms of MB. The association of MICA*029 allele (MICA­A4 variant) with the susceptibility to the MB form suggests this variant for the transmembrane domain of the MICA molecule may be a risk factor for leprosy. Two MICA and nine HLA­B variants were found associated with leprosy per se in the Colônia do Prata population. Linkage disequilibrium analysis revealed perfect linkage disequilibrium (LD) between HLA­B markers rs2596498 and rs2507992, and high LD (R2 = .92) between these and the marker rs2442718. This familial study demonstrates that MICA association signals are not independent from those observed for HLA­B. Our findings contribute the knowledge pool of the immunogenetics of Hansen's disease and reveals a new association of the MICA*029 allele(AU).

Plasma eicosanoid profiles determined by high-performance liquid chromatography coupled with tandem mass spectrometry in stimulated peripheral blood from healthy individuals and sickle cell anemia patients in treatment.

Eicosanoids play an important role in homeostasis and in the pathogenesis of various human diseases. Pharmacological agents such as Ca(2+) ionophores and Ca(2+)-ATPase inhibitors, as well as natural agonists such as formylmethionine-leucyl-phenylalanine (fMLP), can stimulate eicosanoid biosynthesis. The aims of this work were to develop a method to determine the eicosanoid profile of human plasma samples after whole blood stimulation and to assess differences between healthy and sick individuals. For this purpose, a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was partially validated for the quantification of 22 eicosanoids using human plasma from healthy volunteers. In addition, we optimized a method for the stimulation of eicosanoids in human whole blood. LC-MS/MS analyses were performed by negative electrospray ionization and multiple reaction monitoring. An assumption of linearity resulted in a regression coefficient ≥0.98 for all eicosanoids tested. The mean intra-assay and inter-assay accuracy and precision values had relative standard deviations and relative errors of ≤15%, except for the lower limit of quantification, where these values were ≤20%. For whole blood stimulation, four stimuli (fMLP, ionomycin, A23187, and thapsigargin) were tested. Results of the statistical analysis showed that A23187 and thapsigargin were potent stimuli for the production or liberation of eicosanoids. We next compared the eicosanoid profiles of stimulated whole blood samples of healthy volunteers to those of patients with sickle cell anemia (SCA) under treatment with hydroxyurea (HU) or after chronic red blood cell (RBC) transfusion. The results indicate that the method was sufficient to find a difference between lipid mediators released in whole blood of SCA patients and those of healthy subjects, mainly for 5-HETE, 12-HETE, LTB4, LTE4, TXB2, and PGE2. In conclusion, our analytical method can detect significant changes in eicosanoid profiles in stimulated whole blood, which will contribute to establishing the eicosanoid profiles associated with different inflammatory and infectious diseases.

Influence of KIR genes and their HLA ligands in the pathogenesis of leprosy in a hyperendemic population of Rondonópolis, Southern Brazil.

BACKGROUND: The objective of this study was to investigate the association between KIR genes and the immunopathogenesis of leprosy. METHODS: The types of KIR and HLA genes were evaluated by PCR-SSOP-Luminex in 408 patients with leprosy and 413 healthy individuals. Statistical analysis was performed using the Chi-square or Fisher's exact test and stepwise multivariate analysis. RESULTS: There was a higher frequency of activating KIR genes (KIR2DS1, 2DS2 and 3DS1) together with their HLA ligands in the tuberculoid (TT) group as compared to the lepromatous leprosy (LL) group. KIR2DL2/2DL2-C1 was more frequent in the patient, TT and LL groups than in the control group. Borderline patients presented a higher frequency of inhibitory pairs when compared to the control group, and a higher frequency of activating pairs as compared to the LL group. Multivariate analysis confirmed the associations and demonstrated that being a female is a protective factor against the development of the disease per se and the more severe clinical form. CONCLUSIONS: This study showed that activating and inhibitory KIR genes may influence the development of leprosy - in particular, activating genes may protect against the more aggressive form of the disease - thereby demonstrating the role of NK cells in the immunopathology of the disease.

Influence of KIR genes and their HLA ligands in the pathogenesis of leprosy in a hyperendemic population of Rondonópolis, Southern Brazil

BACKGROUND: The objective of this study was to investigate the association between KIR genes and the immunopathogenesis of leprosy. METHODS: The types of KIR and HLA genes were evaluated by PCR-SSOP-Luminex in 408 patients with leprosy and 413 healthy individuals. Statistical analysis was performed using the Chi-square or Fisher's exact test and stepwise multivariate analysis. RESULTS: There was a higher frequency of activating KIR genes (KIR2DS1, 2DS2 and 3DS1) together with their HLA ligands in the tuberculoid (TT) group as compared to the lepromatous leprosy (LL) group. KIR2DL2/2DL2-C1 was more frequent in the patient, TT and LL groups than in the control group. Borderline patients presented a higher frequency of inhibitory pairs when compared to the control group, and a higher frequency of activating pairs as compared to the LL group. Multivariate analysis confirmed the associations and demonstrated that being a female is a protective factor against the development of the disease per se and the more severe clinical form. CONCLUSIONS: This study showed that activating and inhibitory KIR genes may influence the development of leprosy - in particular, activating genes may protect against the more aggressive form of the disease - thereby demonstrating the role of NK cells in the immunopathology of the disease.

Genetic susceptibility to Chagas disease: an overview about the infection and about the association between disease and the immune response genes.

Chagas disease, which is caused by the flagellate parasite Trypanosoma cruzi, affects 8-10 million people in Latin America. The disease is endemic and is characterised by acute and chronic phases that develop in the indeterminate, cardiac, and/or gastrointestinal forms. The immune response during human T. cruzi infection is not completely understood, despite its role in driving the development of distinct clinical manifestations of chronic infection. Polymorphisms in genes involved in the innate and specific immune response are being widely studied in order to clarify their possible role in the occurrence or severity of disease. Here we review the role of classic and nonclassic MHC, KIR, and cytokine host genetic factors on the infection by T. cruzi and the clinical course of Chagas disease.

Role of HLA, KIR, MICA, and cytokines genes in leprosy.

Many genes including HLA, KIR, and MICA genes, as well as polymorphisms in cytokines have been investigated for their role in infectious disease. HLA alleles may influence not only susceptibility or resistance to leprosy, but also the course of the disease. Some combinations of HLA and KIR may result in negative as well as positive interactions between NK cells and infected host cells with M. leprae, resulting in activation or inhibition of NK cells and, consequently, in death of bacillus. In addition, studies have demonstrated the influence of MICA genes in the pathogenesis of leprosy. Specifically, they may play a role in the interaction between NK cells and infected cells. Finally, pro- and anti-inflammatory cytokines have been influencing the clinical course of leprosy. Data from a wide variety of sources support the existence of genetic factors influencing the leprosy pathogenesis. These sources include twin studies, segregation analyses, family-based linkage and association studies, candidate gene association studies, and, most recently, genome-wide association studies (GWAS). The purpose of this brief review was to highlight the importance of some immune response genes and their correlation with the clinical forms of leprosy, as well as their implications for disease resistance and susceptibility.

HLA-A, B and DRB1 allele and haplotype frequencies in volunteer bone marrow donors from the north of Parana State.

BACKGROUND: Knowledge of allele and haplotype frequencies of the human leukocyte antigen (HLA) system is important in the search for unrelated bone marrow donors. The Brazilian population is very heterogeneous and the HLA system is highly informative of populations because of the high level of polymorphisms. AIM: The aim of this study was to characterize the immunogenetic profile of ethnic groups (Caucasians, Afro-Brazilians and Asians) in the north of Parana State. METHODS: A study was carried out of 3978 voluntary bone marrow donors registered in the Brazilian National Bone Marrow Donor Registry and typed for the HLA-A, B and DRB1 (low resolution) loci. The alleles were characterized by the polymerase chain reaction sequence-specific oligonucleotides method using the LabType SSO kit (One Lambda, CA, USA). The ARLEQUIN v.3.11 computer program was used to calculate allele and haplotype frequencies RESULTS: The most common alleles found in Caucasians were HLA-A*02, 24, 01; HLA-B*35, 44, 51; DRB1*11, 13, 07; for Afro-Brazilians they were HLA-A*02, 03, 30; HLA-B*35, 15, 44; DRB1*13, 11, 03; and for Asians they were: HLA-A*24, 02, 26; HLA-B*40, 51, 52; DRB1*04, 15, 09. The most common haplotype combinations were: HLA-A*01, B*08, DRB1*03 and HLA-A*29, B*44, DRB1*07 for Caucasians; HLA-A*29, B*44, DRB1*07 and HLA-A*01, B*08 and DRB1*03 for Afro-Brazilians; and HLA-A*24, B*52, DRB1*15 and HLA-A*24, B*40 and DRB1*09 for Asians. CONCLUSION: There is a need to target and expand bone marrow donor campaigns in the north of Parana State. The data of this study may be used as a reference by the Instituto Nacional de Cancer/Brazilian National Bone Marrow Donor Registry to evaluate the immunogenetic profile of populations in specific regions and in the selection of bone marrow donors.

HLA-A, B and DRB1 allele and haplotype frequencies in volunteer bone marrow donors from the north of Parana state

BACKGROUND: Knowledge of allele and haplotype frequencies of the human leukocyte antigen (HLA) system is important in the search for unrelated bone marrow donors. The Brazilian population is very heterogeneous and the HLA system is highly informative of populations because of the high level of polymorphisms. AIM: The aim of this study was to characterize the immunogenetic profile of ethnic groups (Caucasians, Afro-Brazilians and Asians) in the north of Parana State. METHODS: A study was carried out of 3978 voluntary bone marrow donors registered in the Brazilian National Bone Marrow Donor Registry and typed for the HLA-A, B and DRB1 (low resolution) loci. The alleles were characterized by the polymerase chain reaction sequence-specific oligonucleotides method using the LabType SSO kit (One Lambda, CA, USA). The ARLEQUIN v.3.11 computer program was used to calculate allele and haplotype frequencies. Results: The most common alleles found in Caucasians were HLA-A*02, 24, 01; HLA-B*35, 44, 51; DRB1*11, 13, 07; for Afro-Brazilians they were HLA-A*02, 03, 30; HLA-B*35, 15, 44; DRB1*13, 11, 03; and for Asians they were: HLA-A*24, 02, 26; HLA-B*40, 51, 52; DRB1*04, 15, 09. The most common haplotype combinations were: HLA-A*01, B*08, DRB1*03 and HLA-A*29, B*44, DRB1*07 for Caucasians; HLA-A*29, B*44, DRB1*07 and HLA-A*01, B*08 and DRB1*03 for Afro-Brazilians; and HLA-A*24, B*52, DRB1*15 and HLA-A*24, B*40 and DRB1*09 for Asians. CONCLUSIONS: There is a need to target and expand bone marrow donor campaigns in the north of Parana State. The data of this study may be used as a reference by the Instituto Nacional de Cancer/Brazilian National Bone Marrow Donor Registry to evaluate the immunogenetic profile of populations in specific regions and in the selection of bone marrow donors.