Tuberculosis associated with HLA--B8, BfS in a Newfoundland community study

The Research Progress of Host Genes and Tuberculosis Susceptibility

BACKGROUND/AIMS

Nucleotide diversity may affect the immune regulation of tuberculosis (TB) patients, leading to the individual susceptibility to TB. In recent years, there are a lot of researches on the association of host genetic factors and TB susceptibility which has attracted increasing attention, and the in-depth study of its mechanism is gradually clear.

MATERIALS

We made a minireview on the association of many candidate genes with TB based on recent research studies systematically, such as the human leukocyte antigen (HLA) gene, the solute carrier family 11 member 1 (SLC11A1) gene system, the vitamin D receptor (VDR) gene, the mannan-binding lectin (MBL) gene, the nitric oxide synthase 2A (NOS2A) gene, the speckled 110 (SP110) gene, and the P2X7 receptor (P2X7) gene. The discovery of these candidate genes could reveal the pathogenesis of TB comprehensively and is crucial to provide scientific evidence for formulating the related measures of prevention and cure.

DISCUSSION

The host genes play important roles in the development of TB, and the host genes may become new targets for the prevention and treatment of TB. Effective regulation of host genes may help prevent or even treat TB.

CONCLUSION

This minireview focuses on the association of host genes with the development of TB, which may supply some clues for future therapies and novel drug targets for TB.

Influence of Genetic Polymorphism Towards Pulmonary Tuberculosis Susceptibility

Tuberculosis (TB) is still remains the major threat for human health worldwide. Several case-control, candidate-gene, family studies and genome-wide association studies (GWAS) suggested the association of host genetic factors to TB susceptibility or resistance in various ethnic populations. Moreover, these factors modulate the host immune responses to tuberculosis. Studies have reported genetic markers to predict TB development in human leukocyte antigen (HLA) and non-HLA genes like killer immunoglobulin-like receptor (KIR), toll-like receptors (TLRs), cytokine/chemokines and their receptors, vitamin D receptor (VDR) and SLC11A1 etc. Highly polymorphic HLA loci may influence antigen presentation specificities by modifying peptide binding motifs. The recent meta-analysis studies revealed the association of several HLA alleles in particular class II HLA-DRB1 with TB susceptibility and valuable marker for disease development especially in Asian populations. Case-control studies have found the association of HLA-DR2 in some populations, but not in other populations, this could be due to an ethnic specific association of gene variants. Recently, GWAS conducted in case-control and family based studies in Russia, Chinese Han, Morocco, Uganda and Tanzania revealed the association of genes such as ASAP1, Alkylglycerol monooxygenase (AGMO), Forkhead BoxP1 (FOXP1), C-terminal domain phosphatase 1 (UBLCP1) and intergenic SNP rs932347C/T with TB. Whereas, SNP rs10956514A/G were not associated with TB in western Chinese Han and Tibetan population. In this review, we summarize the recent findings of genetic variants with susceptibility/resistance to TB.

Genetic susceptibility in tuberculosis

The importance of host genetic factors in determining susceptibility to tuberculosis (TB) has been studied extensively using various methods, such as case-control, candidate gene and genome-wide linkage studies. Several important candidate genes like human leucocyte antigen/alleles and non-human leucocyte antigen genes, such as cytokines and their receptors, chemokines and their receptors, pattern recognition receptors (including toll-like receptors, mannose binding lectin and the dendritic cell-specific intercellular adhesion molecule-3 grabbing nonintegrin), solute carrier family 11A member 1 (formerly known as natural resistance-associated macrophage protein 1) and purinergic P2X7 receptor gene polymorphisms, have been associated with differential susceptibility to TB in various ethnic populations. This heterogeneity has been explained by host-pathogen and gene-environment interactions and evolutionary selection pressures. Although the achievements of genetics studies might not yet have advanced the prevention and treatment of TB, researchers have begun to widen their scope of investigation to encompass these practical considerations.

TB and coeliac disease

We report 2 cases of pulmonary tuberculosis, which did not respond to adequate therapy. Both these patients were later found to have coeliac disease, which led to malabsorption of the TB medications. On treating the coeliac disease with a gluten free diet, the patients responded to TB treatment.

Genetic susceptibility to infectious disease

Our understanding of the variation in individual clinical responses to pathogens has become increasingly relevant, particularly in the face of new emerging epidemics as well as the increasing number of multi-drug-resistant organisms. An effective immune response to infection has contributed to the development of host genetic diversity through selective pressure, with an increasing number of studies characterizing the role that host genetics plays in disease susceptibility. Knowledge of the role host mechanisms play in the pathogenesis of infectious disease can contribute to the design of new therapeutic strategies. Rapid advances in the field of human genomics offer great opportunities for adopting this approach to find new insights into pathogenesis.

Comparative analysis of HLA class I antigens in pulmonary sarcoidosis and tuberculosis in the same ethnic group

OBJECTIVE

To compare occurrences of respective HLA class I antigens in patients with sarcoidosis (SA), patients with tuberculosis (TB), and healthy controls in the same ethnic group in Poland.

PATIENTS AND METHODS

HLA-A, -B, and -C antigens were determined from 1994 to 1997 by using the National Institutes of Health method in 100 patients with SA, 100 patients with TB, and 100 healthy controls. Frequencies of specific antigens were compared among the 3 groups.

RESULTS

Our study showed that among SA patients, the HLA-B51(5) and HLA-B8 antigens tended to be more common and the HLA-B13, -B35, and -Cw4 antigens tended to be less common than in the controls. However, after Bonferroni correction, only the HLA-B35 antigen was found to be significantly different in SA patients and controls. In TB patients, the expression of HLA-B62(15) and HLA-Cw5 antigens tended to be more common compared with controls and HLA-A2 less common compared with controls, but only the differences in B62(15) and Cw5 were significant after Bonferroni correction. HLA-B51(5) and HLA-B8 antigens were statistically more frequent and B13, B62(15), and Cw4 less frequent in SA than in TB patients and remained significant after Bonferroni correction. The occurrence of other antigens studied in both populations was comparable.

CONCLUSION

We identified associations of HLA class I antigens in patients with SA or TB, with an expression pattern specific and different for each group.

Comparing epidemic tuberculosis in demographically distinct heterogeneous populations

There is wide variation in endemic tuberculosis (TB) levels between countries and we seek to identify possible causes of these differences. In this study we present an epidemiological model of Mycobacterium tuberculosis infection to investigate the effects of host genetics and demographic factors on epidemic TB. We discuss the general framework for this approach and present analytical results to identify important parameters affecting steady-state prevalence and incidence rates of TB disease. We then use numerical simulations of our model to observe the effects of a genetically susceptible subpopulation on TB disease dynamics at the population level. Finally, we simulate infection within a genetically heterogeneous population in two demographic settings: India (a typical population with high TB prevalence) and the USA (a typical population with low TB prevalence). Results show that changes in transmission parameters, the fraction of the population genetically susceptible to infection, and demographic factors strongly affect TB prevalence and incidence rates.

Molecular subtypes of the HLA-DR antigens in pulmonary tuberculosis

OBJECTIVE

The aim of this study was to analyze association between HLA-DRB1 alleles and pulmonary tuberculosis (PTB) in the Polish population.

METHODS

The HLA-DRB1 typing was performed using sequence-specific amplification (polymerase chain reaction with sequence specific primer [PCR-SSP] in 31 patients and 58 healthy volunteers. The DRB1 primers were supplied by DYNAL in the standard kit DYNAL DR "low-resolution"-SSP.

RESULTS

The study showed that the DRB1*16 alleles frequency was higher in patients with PTB than in the tested group of healthy controls (P < 0.01). When HLA-DR2 alleles were combined (i.e., the DRB1*15 with DRB1*16 alleles), their frequency was comparable with that in the healthy individuals. The highest relative risk (RR) of tuberculosis was associated with DRB1*16 alleles (RR = 9.7). When HLA-DR6 alleles were combined (i.e., the DRB1*13 with DRB1*14 alleles), only a trend for higher frequency in patients with PTB was found. Frequency of DRB1*13 alleles of HLA-DR6 was significantly lower in PTB than in the healthy individuals (P < 0.001; RR = 0.04).

CONCLUSIONS

Results suggest that the presence of HLA-DRB1*16 alleles may increase the risk of development of PTB, whereas HLA-DRB1*13 alleles may be resistant to tuberculosis.

An RFLP map for 2q33-q37 from multicase mycobacterial and leishmanial disease families: no evidence for an Lsh/Ity/Bcg gene homologue influencing susceptibility to leprosy

The mycobacterial diseases leprosy and tuberculosis (TB) and the leishmaniases are characterized by a wide spectrum of disease phenotypes, and by the fact that the majority of individuals exposed to the causative organisms Mycobacterium leprae, M. tuberculosis and Leishmania sp. become infected but do not present with clinical disease. In order to determine whether a human homologue to the murine macrophage resistance gene Lsh/Ity/Bcg influences susceptibility to human disease, multicase families for all three diseases have been collected, and linkage analysis performed using a panel of markers in the region of human chromosome 2q33-q37 known to be conserved with the Lsh/Ity/Bcg-containing region of murine chromosome 1. Because of the paucity of available polymorphic markers/linkage information for 2q33-q37, data from 35 multicase leprosy, TB and visceral leishmaniasis families (310 individuals) were first pooled to produce a detailed RFLP map of the region. Peak LOD scores well in excess of 3 were observed for linkage between adjacent pairs of a more proximal (2q33-q35) set of markers CRYGP1, MAP2, FN1, TNP1, VIL1 and DES, and between adjacent pairs of a more distal (2q35-q37) set COL6A3, D2S55 and D2S3. These peak LOD scores and the corresponding values for theta were used in the MAP92 program to generate a multiple two-point map with gene order/map intervals (cM) of: CRYGP1-4.65-MAP2-3.45-FN1-5.95-TNP1-3.41-VIL1-3. 01- DES-20.14-COL6A-10.91-D2S55-3.67-D2S3. Although local support for the placement of loci in this order was weak (LOD < 2, except for DES-COL6A3 where LOD = 6.02), the map is consistent with the gene order for those loci (Cryg, Fn-1, Tp-1, Vil, Des, Col6a3) previously mapped in the mouse. Data from 17 multicase leprosy families (149 individuals) were further analysed for linkage between a putative disease susceptibility locus (DSL) controlling susceptibility to leprosy per se and each of the marker loci. Assuming 100% penetrance for the susceptibility allele, no positive LOD score was obtained for linkage between the DSL and any of the marker genes. Instead, the data provide convincing evidence (LOD scores < -2) that a DSL does not fall within 10-20 cM of CRYGP1, MAP2, TNP1, VIL1, DES or D2S55, or within 5-10 cM of FN1, COL6A3 or D2S3. This effectively excludes a putative DSL controlling susceptibility to leprosy per se from the entire region 2q33-q37.(ABSTRACT TRUNCATED AT 400 WORDS)

No association or linkage with HLA-DR or -DQ genes in South Indians with pulmonary tuberculosis

Studies of the HLA class II genes were performed in patients and multiple families with pulmonary tuberculosis from South India to seek any association of disease susceptibility with an individual allele or haplotype. TaqI RFLP analysis of HLA-DRB, -DQA and -DQB genes was done in 38 patients and 36 healthy control subjects. No significant association with any particular allele or haplotype was obtained. Linkage analysis performed in 12 families and haplotype sharing analysis in 9 families showed that the genetic susceptibility to pulmonary tuberculosis was not linked to the HLA region. The results suggest that the RFLP patterns of HLA class II genes DRB, DQA and DQB are not associated with susceptibility to pulmonary tuberculosis and that the genes controlling susceptibility or resistance may be located outside the HLA region.

An immunogenetic view of delayed type hypersensitivity

This review, the third in the series on cellular immune reactivity to tubercle bacilli in the centenary year of Koch's classical paper describing this phenomenon and its possible implications, represents an immunogenetic point of view. In fact this will be quite a broad point of view by an immunogeneticist who is not hampered by specific knowledge on therapy or prevention of tuberculosis. In this respect I probably do not differ very much from Robert Koch 100 years ago! An important difference, however, is that we think we now understand a great deal of the cellular and molecular basis of the immunological phenomena observed by Koch. Immunogenetics has contributed considerably to our current understanding and I will try to review that contribution here. Because thus far my main research interest has been in another mycobacterium, namely Mycobacterium leprae, I will use M. leprae and leprosy as an example to illustrate some ideas. The message of this review is that there is a reason for optimism: the knowledge recently gained by cellular and molecular immunologists as well as immunogeneticists has straightforward implications for the rational development of subunit vaccines and immunotherapeutic strategies.

Association of pulmonary tuberculosis and HLA in south India

In 204 patients with smear-positive pulmonary tuberculosis HLA-A10, B8 and DR2 were more frequently found than in 404 control subjects (p = 0.01); the greatest attributable risk (0.29) was associated with HLA-DR2. The radiographic extent of disease was also associated with HLA-DR2 (p = 0.0001). In 152 patients with smear-negative pulmonary tuberculosis, the frequencies of HLA-A10 and B8, but not DR2, were greater in the control subjects (p = 0.001 and 0.01 respectively). HLA-DR2 may be involved in the pathogenesis of advanced pulmonary tuberculosis. Study of endogamous, genetically disparate populations (caste) revealed other HLA associations (A3, B12 and DR4) unique to them, suggesting that genes linked with the HLA complex might also be significant in the pathogenesis of tuberculosis.

Tuberculosis in patients with various HLA phenotypes

Tuberculosis patients and healthy subjects from six ethnic groups of the Soviet Union were HLA-A, -B, -C, and DR typed. The frequencies of the HLA-A, -B and -C antigens differed amongst the ethnic groups. With all groups, however, patients with tuberculosis showed a significantly increased frequency of HLA-DR2 and a reduced frequency of HLA-DR3 type. Unfavourable dynamics of tuberculosis was significantly associated with an increased incidence of B15 and DR2 and a reduced incidence of B27 and DR3. Family studies revealed that the inheritance of susceptibility to tuberculosis (from parent to offspring) is associated with the inheritance of certain HLA haplotypes. Tuberculosis patients bearing the DR2 antigen had increased levels of IgG antibodies to PPD and the frequency of B7 and, more particularly, DR2 was higher in anergic patients.

Association of HLA and other genetic markers in South Indian patients with pulmonary tuberculosis

Histocompatibility antigens (A, B & C loci) and 23 other single gene characters were studied in 204 pulmonary tuberculosis patients belonging to a single endogamous group in South India. None of the previously reported associations with HLA antigens was confirmed, nor any new one found. The blood O and Rh negative associations were also not confirmed, although a new association with the Jk blood group system appears possible. Of particular interest is the association with the phosphoglucomutase (PGM1) system, which parallels that found in a different population located some 1000 km away. Relative risks were calculated to measure the resistance of individuals with the PGM1*2+ allele.

HLA-A and B antigens and pulmonary tuberculosis in Greeks

A significantly increased frequency of the HLA-B27 antigen was found in Greek adult patients suffering from pulmonary tuberculosis. This finding is discussed in connection with the literature, and it is suggested that the HLA system is involved in the pathogenesis of the disease.

Study on the association of HLA with pulmonary tuberculosis

The association between HLA and pulmonary tuberculosis was investigated in 50 Chinese patients. The frequencies of the HLA-A11 and -B15 antigens were increased (P less than 0.025) in patient group. Relative risks (R.R.) were 2.13 and 2.39, respectively. In contrast, the frequency of the HLA-Cw3 antigen and the R.R. (0.29) were decreased (P less than 0.005) in the patient group. These results are different from those reported by other researchers for Caucasian and Chinese tuberculosis patients. Moreover, it was found that the frequency of the A11-B15 haplotype in all patients with cavitation was 3-4 times higher (P less than 0.01) than in control individuals. The R.R. was 3.57.

HLA-antigens and tuberculosis in the Egyptian population

Peripheral blood lymphocytes from 42 unrelated Egyptian patients with tuberculosis and 156 healthy persons were HLA phenotyped for the A,B and DR loci using the NIH lymphocytotoxicity tests. Statistical analysis of the results showed that A2 and B5 had significantly increased frequencies among patients with tuberculosis compared with the controls. Patients with A2 had more severe disease than did patients without A2 and the number with B5 antigen was less than those without the antigen. This observation suggests that A2 and B5 may influence susceptibility to tuberculosis, but not the course of the disease. Furthermore, a linkage disequilibrium was found between A2 and B5 antigen among tuberculous patients, but their association bore no relation to the severity of the disease.

Human leukocyte antigens and circulating immunoglobulin levels in Indian patients with pulmonary tuberculosis

Histocompatibility antigens (-A, -B and -C loci) and circulating antibodies (IgG, IgM, IgA and IgE) were studied in 63 pulmonary tuberculosis patients and regionally matched healthy volunteers from Uttar Pradesh, India. A previously described association with antigen B15 in an heterogeneous sample of North India was not confirmed but a slight increase of antigen B18 was found. The levels of immunoglobulins in the plasma of these patients showed a significant increase in IgG, IgA and IgE. Although the increased levels of IgG and IgA are in agreement with previous studies, the role of the increased IgE is not clear and needs further investigation. Patients who were antigen B14 and B18 positive tend to show significantly low levels of IgG, which suggests a possible genetic influence on the expression of immunoglobulin levels.

Racial differences in susceptibility to tuberculosis: risk of disease after infection

It is generally believed that certain racial groups are highly susceptible to tuberculosis disease while others have developed a "natural resistance." Epidemiological studies reporting differences in case rates among different racial groups, provide inconclusive evidence. Many factors influence the development of active tuberculosis including sex, age, body weight, and virulence of the infecting organism. These, as well as other factors, may be more important determinants which, up to now, have been confused with race.

Association between phosphoglucomutase (PGM1) and group-specific component (Gc) subtypes and tuberculosis

The polymorphism of PGM1 and Gc was studied by isoelectric focusing in pulmonary tuberculosis patients and controls. For the Gc system, the phenotypic frequencies did not differ significantly, but the PGM1 system showed a significant difference in the tuberculosis patients compared to controls. The data presented here show the potential of newly developed techniques to distinguish subjects with susceptibility to disease.

HLA-A, -B, -C and -DR antigen profile in pulmonary tuberculosis in North India

Investigations for the HLA-A, -B, -C and -DR antigens were conducted on 124 random North Indian patients with confirmed diagnosis of pulmonary tuberculosis by the demonstration of acid fast bacilli in the sputum. 109 appropriately matched controls from the same ethnic background were also tissue typed. No significant deviation was observed in the HLA-A, -B, and -C locus antigens. With the HLA-DR typing, there was a marginal increase in DR2 and a concurrent significant decrease in DRw6 in the patient group. These deviations were, however, insignificant when correction for the P value was made. ABO blood group typing results indicate that blood group 'O' may afford protection against TB. The involvement of both DR2 and DRw6 is interesting as it is also implicated in leprosy, another mycobacterial disease. The results suggest the possibility of a common gene in the MHC for both tuberculosis and leprosy.