Role of HLA class I (HLA-A, B) and HLA class II (HLA-DRB, DQB) in HIV-1 patients with and without pulmonary tuberculosis

Clinical and genetic markers associated with tuberculosis, HIV-1 infection, and TB/HIV-immune reconstitution inflammatory syndrome outcomes

BACKGROUND

Tuberculosis (TB) and AIDS are the leading causes of infectious disease death worldwide. In some TB-HIV co-infected individuals treated for both diseases simultaneously, a pathological inflammatory reaction termed immune reconstitution inflammatory syndrome (IRIS) may occur. The risk factors for IRIS are not fully defined. We investigated the association of HLA-B, HLA-C, and KIR genotypes with TB, HIV-1 infection, and IRIS onset.

METHODS

Patients were divided into four groups: Group 1- TB+/HIV+ (n = 88; 11 of them with IRIS), Group 2- HIV+ (n = 24), Group 3- TB+ (n = 24) and Group 4- healthy volunteers (n = 26). Patients were followed up at INI/FIOCRUZ and HGNI (Rio de Janeiro/Brazil) from 2006 to 2016. The HLA-B and HLA-C loci were typed using SBT, NGS, and KIR genes by PCR-SSP. Unconditional logistic regression models were performed for Protection/risk estimation.

RESULTS

Among the individuals with TB as the outcome, KIR2DS2 was associated with increased risk for TB onset (aOR = 2.39, P = 0.04), whereas HLA-B*08 and female gender were associated with protection against TB onset (aOR = 0.23, P = 0.03, and aOR = 0.33, P = 0.01, respectively). Not carrying KIR2DL3 (aOR = 0.18, P = 0.03) and carrying HLA-C*07 (aOR = 0.32, P = 0.04) were associated with protection against TB onset among HIV-infected patients. An increased risk for IRIS onset was associated with having a CD8 count ≤500 cells/mm3 (aOR = 18.23, P = 0.016); carrying the KIR2DS2 gene (aOR = 27.22, P = 0.032), the HLA-B*41 allele (aOR = 68.84, P = 0.033), the KIR2DS1 + HLA-C2 pair (aOR = 28.58, P = 0.024); and not carrying the KIR2DL3 + HLA-C1/C2 pair (aOR = 43.04, P = 0.034), and the KIR2DL1 + HLA-C1/C2 pair (aOR = 43.04, P = 0.034), CONCLUSIONS: These results suggest the participation of these genes in the immunopathogenic mechanisms related to the conditions studied. This is the first study demonstrating an association of HLA-B*41, KIR2DS2, and KIR + HLA-C pairs with IRIS onset among TB-HIV co-infected individuals.

Analysis of HLA association among North Indian HIV-positive individuals co-infected with Mycobacterium tuberculosis

BACKGROUND

Genetic variation in HLA genes influence the immune response and may thus contribute to differential development of tuberculosis (TB) in HIV-infected individuals. The study was designed to determine whether HLA polymorphisms influence the development of Mycobacterium tuberculosis infection in HIV-infected individuals.

MATERIALS AND METHODS

Fifty HIV-positive individuals without TB (HIV+TB-), 50 HIV patients co-infected with TB (HIV+TB+) and 50 control subjects (HIV-TB-) were analyzed for HLA Class I and II polymorphisms.

RESULTS

In HLA Class II, frequency of occurrence of DRB1*13 (OR 3.165, CI 1.176-8.518, P value 0.019), DRB5 (OR 2.253, CI 1.011-5.019, P value 0.045) and DQB1*06 (OR 2.705, CI 1.197-6.113, P value 0.016) were increased in HIV+TB+compared to HIV+TB-. HLA DQB1*02 (OR 0.436, CI 0.185-1.029, P value 0.05) on the other hand conferred a protective role. In HLA Class I, frequency of B*15 (OR 2.705, CI 1.040-7.036, P value 0.038) was increased, whereas B*51 (OR 0.148, CI 0.031-0.706, P value 0.007) was decreased in HIV+TB+group compared to HIV+TB-. These differences however were not significant when compared with healthy controls.

CONCLUSION

HLA polymorphisms independently did not account for the susceptibility to either of the disease mostly, although they seem to play a role once the infection(s) has established in a particular individual. Further studies are needed on a larger sample size to confirm these observations.

Human leukocyte antigen B distribution in HIV discordant cohort from India

Limited reports are available on association of HLA-B with HIV infection from India, a home to the third largest population of HIV infected people in the world. This emphasizes the need to have more information specifically the genetic constitution of HIV serodiscordant couples (DCs), where one spouse is seropositive (HSP) while the other remains seronegative (HSN) even after repeated exposure. Hence, aim of this study was to document association of HLA-B with HIV infection in DCs living in Mumbai, India. A cohort was designed to enroll DCs attending the ICTC/Shakti Clinic of KEM Hospital, Mumbai. A group of unexposed volunteers were also enrolled as healthy controls (HC). HLA-B alleles were typed using sequence-specific oligonucleotide probes. Allele frequency comparison was done using 2×2 contingency tables. Results were considered significant, when p<0.05 with two-tailed Fisher's exact test. At HLA-B locus, the frequencies of HLA-B*40;-B*35;-B*07;-B*15;-B*51;-B*44;-B*52;-B*37 and -B*57 were found in decreasing order in the population. Frequency of HLA-B*35 allele was significantly higher (HSP vs HSN; p<0.02 and HSP vs HC; p<0.04) in HSP. HLA-B*40 (HSN vs HSP; p<0.01 and HC vs HSP; p<0.01) and HLA-B*18 (HSN vs HSP; p<0.02) were significantly associated with HSN. Both HSN and HC had similar HLA-B*35 and -B*40 allele frequency. HLA-B*57 allele was observed in 15 individuals (3.69%). However, HLA-B*57:01 which is known to be associated with adverse reactions against Abacavir was observed in 7 of them. HLA-B*39 was observed exclusively in HSP. Our observation in DCs confirmed the association of HLA-B*35 with susceptibility while HLA-B*40 (specifically *B40:06), -B*18 with protection. These identified alleles can be used as possible marker associated with HIV transmission. In India, HLA screening is not carried out before initiation of HIV treatment. However, the presence of HLA-B*57:01 in the population emphasizes the importance of such screening to predict/avoid Abacavir hypersensitivity.

HLA-DRB1 may be antagonistically regulated by the coordinately evolved promoter and 3'-UTR under stabilizing selection

HLA-DRB1 is the most polymorphic MHC (major histocompatibility complex) class II gene in human, and plays a crucial role in the development and function of the immune system. Extensive polymorphisms exist in the promoter and 3'-UTR of HLA-DRB1, especially a LTR (Long terminal repeat) element in the promoter, which may be involved in the expression regulation. However, it remains unknown how the polymorphisms in the whole promoter region and 3'-UTR to regulate the gene expression. In this study, we investigated the extensive polymorphisms in the HLA-DRB1 promoter and 3'-UTR, and how these polymorphisms affect the gene expression in both independent and jointly manners. It was observed that most of the haplotypes in the DRB1 promoter and 3'-UTR were clustered into 4 conserved lineages (H1, H2, H3 and H4), and showed high linkage disequilibrium. Compared with H1 and H2 lineage, a LTR element in the promoter of H3 and H4 lineage significantly suppressed the promoter activity, whereas the activity of the linked 3'-UTR increased, leading to no apparent difference in the final expression product between H1/H2 and H3/H4 lineage. Nevertheless, compared with the plasmid with a promoter and 3'-UTR from the same lineage, the recombinant plasmid with a promoter from H2 and a 3'-UTR from H3 showed about double fold increased luciferase activity, Conversely, the recombinant plasmid with a promoter from H3 and a 3'-UTR from H2 resulted in about 2-fold decreased luciferase activity. These results indicate that the promoter and 3'-UTR of HLA-DRB1 may antagonistically regulate the gene expression, which may be subjected to stabilizing selection. These findings may provide a novel insight into the mechanisms of the diseases associated with HLA-DRB1 genes.