Susceptibility toTuberculosis

• CONTENT• INTRODUCTION• GENOME SCAN• CANDIDATE GENES• CONCLUSION

• Prepared by,• Nadia Hassan• Walaa Abdalla

INTRODUCTION

Tuberculosis, primarily caused by Mycobacterium tuberculosis, continues to be an important public health problem despite the existence of national and international tuberculosis control programs. Recent data from the World Health Organization show that about 8-10 million new cases arise annually and eventually 2-3 million die of the disease every year..

• Tuberculosis is one of the major infections that cause disease and death worldwide. It is estimated that one-third of the World's population is infected with M. tuberculosis, but that only one in ten (10%) of those infected ever develop clinical disease

DIALECTICS OF SUSCEBTIBILITY

IMMUNE

RESPONSE

AGAINSTBACTERIA

GENETIC & NON

GENETIC FACTORS OFM.TUBERCULO

SIS

ENVIROMENTAL

FACTORSe.g.

Malnutrition, poor economic

condition

GENETIC & NON

GENETIC FACTORS OF

HOST

RISK FACTORSInclude;• PATIENTS WITH DIABETES MELLITUS ARE AT

INCREASED RISK.• TWIN STUDIES SHOWED THAT SUSCEPTIBILITY TO

TUBERCULOSIS WAS INHERITED .• PATIENTS WITH VITAMIN D DEFICIENCY.

HOWEVER, TRANSMISSION IS BY INHALING INFECTED DROPLETS FROM TB PATIENTS WHEN THEY COUGH , SNEEZE, SPEAK OR SPIT.

TUBERCULOSIS

PULMONARY TUBERCULOSIS

CLASSIC SUMPTOMS ARE CHRONIC

COUGH WITH BLOOD TINGED SPUTUM &

WEIGHT LOSS

EXTRA PULMONARY

TUBERCULOSISe.g. CAN AFFECT CNS,LYMPHATIC

SYSTEMTUBERCULOUS

MENINGITIS

DIAGNOSIS

CLINICAL DIAGNOSISRADIOLOGY

CHEST EXAMINATION

LAB DIAGNOSISBLOOD TESTS e.g.

ESRMICROSCOPIC

EXAMINATION &CULTURE

MOLECULAR BIOLOGY

DIAGNOSIS USING PCR TECHNIQUE

TUBERCULOSIS IN SUDAN

• TB is a significant health problem in Sudan.• No study concerning genetic control of human

susceptibility to TB is done in Sudan .• Study concerning epidemiology & drug resistance

patterns of Mycobacterium Tuberculosis isolates was done in eastern Sudan (Kassalla & Gadaref state).

Prof.Maowia Mukhtar, project coordinator.• National centre for prevention of Tuberculosis works

on the development of this health problem.

Genome wide scan (linkage analysis)

• Human genetic variation is an important determinant of the outcome of infection with Mycobacterium tuberculosis. Two-stage genome-wide linkage study was conducted to search for regions of the human genome containing tuberculosis-susceptibility genes. This approach uses sibpair families that contain two full siblings who have both been affected by clinical tuberculosis. For any chromosomal region containing a major tuberculosis-susceptibility gene, affected sibpairs inherit the same parental alleles more often than expected by chance.

• In the first round of the screen, 299 highly informative genetic markers, sibpairs from Gambia and South Africa. 7 chromosomal regions that showed provisional evidence of coinheritance with clinical tuberculosis were identified.

• Second round/ 22 markers from these regions were genotyped in a second set of sibpairs from the same countries.

• Markers on chromosomes 15q and Xq showed suggestive evidence of linkage (lod = 2.00 and 1.77, respectively) to tuberculosis. The potential identification of susceptibility loci on both chromosomes 15q and Xq was supported by an independent analysis designated common ancestry using microsatellite mapping (CAM). (Richard Bellamy, et al. 2000)

Multipoint maximum lod score analysis for chromosomes 15 and X for combined screen 1 and 2 data, calculated by using mapmaker/sibs. (Proc Natl Acad Sci U S A. 2000 July 5; 97(14): 8005–8009)

• A full microsatellite genome scan was conducted by studying three different phenotypes in Kampala and Uganda (Catherine M. 2008)

• Many other chromosomal regions were found to be linked with TB e. g 2q35, 8q12-q13, 11q12.3, 17q11-q21. (Celia MT, et al 2000), (Baghdadi, et al 2006), (Miller, et al 2004) (Jamieson, et al 2004)

Plot of linkage results for chromosome 20.

Candidate genes

Many candidate genes have been identified from the different chromosomal regions and most of them are related to regulation of the cells and products of the immune

system.

HLA system (6p21)

Genetic susceptibility to pulmonary tuberculosis (PTb) has been associated with the HLA (Antigens of the Human Leukocytes) system of the MHC (Major Histocompatibility Complex), mainly with HLA-DR and-DQ antigens. Alleles Haplotypes P value Study country

HLA-DR11(5) DR16(2) DQ7(3)

DR11(5)-DQ7(3) DR14(6)-DQS(1) DR16(2)-DQ7(3)

p<0.05 North eastern Mexico (Rojas Alvarado ML, et al. 2008)

homozygosity for HLA-DQ beta57-Asp

1-reduced ability to bind a peptide2-IFN-gamma from CD4+ T cells significantly less than presented by an HLA-DQ-beta allele encoding an alan at codon 57.

p = 0.001 Cambodia (Delgado JC, et al. 2006)

DRB1*0803 DQB1*0601 1- drug resistance

2-disease recurrence

p = 0.012

p = 0.005 Korea (Kim HS, et al.

2005)

DRB1*1302 DQB1*0301-0304

1- DRB1*1302 DQB1*0602/3 2- DRB1*1101-1121 DQB1*0301-0304

significant Venda of South Africa. (Lombard Z, et al. 2006)

Only type HLA-DRB1*15

X2=0.04311 Egypt. (Saad AH, et al. 2006)

HLA-DRB1*02 and its subtype DRB1*1501

significant India. (Shanmugalakshmi S, et al. 2002)

HLA-B18 HLA-B7 and HLA-B61 (protect against the disease)

north-eastern Romania. (Vasilca V, et al. 2004)

HLA-B51 HLA-B52 (protective association)

P<0.0001 P<0.0001

India. (Vijaya LV, et al. 2006)

DRB1*04 (susceptibility with cavity formation) DRB1*11 (associated with protection)

p=0.01 p=0.003

Syria. (Harfouch HEI, et al. 2008)

HLA-DRB1*07 and HLA-DQA1*0101 HLA-DQA1*0301 and 0501 (protective alleles )

DRB1*11501, QDQA1*0103 and DQB1*0601

P = 0.025 P = 0.04 P = 0.033 P = 0.045

Iran. (Amirzargar AA, et al. 2004)

(SLC11A1 gene) natural-resistance-associated macrophage protein 1 (NRAMP1) (2q35)NRAMP spans 12kb and has 15 exons encoding a 550 amino acid protein showing 85% identity (92% similarity) with Nramp . It regulates early innate responses to intracellular pathogens.SLC11A1 influences tuberculosis susceptibility by regulation of interleukin-10.

Locus Allele Genotype P value Study countryD543N3'UTRINT4 polymorphisms

- TGTG- INT4 polymorphisms (no significant association with TB)

TGTG+/del genotype

P=0.041P=0.030 (Both loci were not associated in the 2nd study and associated in the 3rd)

1-China. (Liu W, et al. 2003)2-México. (Mino MP, et al. 2007)3-China.(Leung KH, et al. 2007)

3'UTR polymorphism

TGTG 1-TGTG/TGTG del2-homozygous TGTG del/TGTG del

P < 0.01

P = 0.013 1-China (Hans). (Duan HF, et al. 2003)

2-South Africa. (Hoal EG, et al. 2004)

NRAMP1 INT4 gene

G > C mutation of intron 4 of (i. e C allele)

G/C and not the normal G/G

China. (QU YB, et al. 2006)

1-INT4 1,2- 5‘ (CA)n microsatellite

The association only found in aboriginal ethnicity in Hualien, eastern Taiwan not among Hans. +ve association in the 2nd study.

1- p = 0.0070 p = 0.00312- P=0.014

1-Taiwan. (Hsu YH, et al. 2006)2-Denmark. (Soborg C, et al. 2007)

microsatellite polymorphism (ATA)n in intron 8

(ATA)n alleles (No significant difference in allele frequency between diseased and control)

USA. (Awomoyi A, et al. 2006)

NRAMP1 polymorphisms(No association )

Morocco. (El Baghdadi J, et al . 2003)

NRAMP1 polymorphisms (No association )

D543N A allele (associated with cavitary lesions)

Japan. (Abe T, et al. 2003)

Interferon-γ (IFNgamma) and IFNgamma receptor

Cytokine gene polymorphisms may alter Th1/Th2 balance with major implications in tuberculosis. Allele or locus Association P value Study areaIFNgamma +874A allele (12q14)

1-NO significant difference2-3.75-fold increased risk

p=0.0017 1-India. (Vigyarani M. 2006)

2-Spain. (Lopez MD, et al. 2003)

+874T/A polymorphism

No association P = 0.024

Turkey. (Sallakci N, et al. 2007)

Texas, USA. (Moran A, et al. 2007)

IFNgamma +874T allele

protective significant association (TB resistance)

P= 0.0008Brazil. (Pacheco AG, et al. 2008)

+874A-->T polymorphism

1- association study2-Family based study (TDT)(The transcription factor NFkappaB binds preferentially to the +874T allele)

p=0.0055 South Africa. (Rossouw M, et al. 2003)

(CA)(22) allele (in the fifth intron of the IFNGR1 gene)(6q23-24)

Protective(significant association with GT promoter haplotype (-611; -56) 2-No association between receptor polymorphism in the 2nd and 3rd study.

1-Norway. (Bulat KL, et al. 2006)

2-Iran. (Mirsaeidi SM, et al. 2005)

3-Gambia. (Awomoyi AA, et al 2004)

allele CA(12) genotype CA(12)/CA(12)

associated with protection

p=0.004 Indonesia. (Sahiratmadga E, et al. 2007)

IFN gamma R11-(CA)(25)allele 2-(CA)(26)allele

1-Susceptible2-protective

1-P = 0.0017

2-P = 0.012 China. (Ding S, et al. 2008)

Interleukins

ILs participate in the inflammatory response required for the immunological control of a broad spectrum of infectious agents.

ILs genes Allele or genotype

Association P value Study area

IL1(2p13-2q11)

IL1B+3,953 T-allele

strong protection

Colombia. (Gomez LM, et al. 2006)

IL8 homozygous 251A allele

1-transmitted to TB-infected children (TDT)2-not associated

P=0.02 1-Texas, USA. (Ma X, et al. 2003)

2-Gambia. (Cooke GS, et al. 2004)

IL12(encodes IL23)

1-IL12B promoter heterozygosity2- IL12B 3' UTR

1-associated with protection2-not associated

p=0.03 1-Indonesia. (Sahiratmadga E, et al. 2007)2-USA.(Ma X, et al. 2003)

IL12B promoter 1-heterozygous A and K haplotypes( composed of, intron 2, intron 4, and 3' UTR alleles)2-homozygous BB haplotypes3-intron 2-repeat marker (ATT)8

1-risk haplotypes2-protective haplotypes 3-2.1-fold increased risk

P < .001 China. (Tso HW, et al. 2004)

IL12RB1(19p13.1)

R214-T365-R378 allele

diminish receptor responsiveness to IL-12 and IL-23, leading to partial dysfunction of IFN-gamma-mediated immunity.

P=0.013 Japan. (Akahoshi M, et al. 2003)

IL-10 1-1082 G/A alleles2-GCC and ACC haplotypes

influence the Th1/Th2 balance

P= 0.004 Turkey. (Ates O, et al. 2008)

toll-like receptor variants

TLRs have been reported to recognize mycobacterial antigens and initiate an immune response.

TLRs genes Allele or genotype

Association P value Study area

TLR1 TLR6 TLR10

1-TLR1-248S, TLR1-602I 2-TLR6-249S

1-significantly alter innate immune responses. 2-TLR6 variants were defective in their ability to mediate NF-kappa B signal transduction

USA. (Ma X, et al. 2003) . USA. (Xin Ma, et al.

2007)

TLR2 (4q32) genotype 597CC development of TBM and miliary TB

Vietnam. (Thuong NT, et al. 2007)

TLR8(chromosome X )

four TLR8 polymorphisms including a non-synonymous polymorphism rs3764880

evidence of association in males (Study groups from Indonesia and Russia)

P = 0.03 Singapore. (Davila S, et al. 2008)

MCP-1 promoter variants (17q11.2) monocyte chemoattractant protein-1 (MCP-1) cytokine plays a role in recruitment of monocytes to the site of

infection.Allele Association P value Study areaG allele of the MCP-1 promoter polymorphism at position -2581

1-strongly associated with increased susceptibility to TB2-associated with resistance3-no evidence of association

1-χ2 of 12.9 (P = 0.0003)χ2 of 32.28 (P = 0.0001)2- P = 0.00123- P = 0.86

1-MexicoKorea2-Ghana, West Africa3-Russia(Pedro O. Flores-Villanueva, et al, J Exp Med. 2005)

MCP-1 -362 variant the effect of -2581 may in part be explained by its LD with -362.

Ghana(Thye T, Nejentsev S,

Entemann CD et al. 2009)

MCP-1 genotypes AG and GG(-2518 GG genotypes)

MCP-1 genotype GG produce high concentrations of MCP-1, which inhibits production of IL-12p40 in response to M. tuberculosis and increases the likelihood that M. tuberculosis infection will progress to active pulmonary tuberculosis.

P < 0.01 Mexico. (Flores VPO, et al. 2005)

China. (Xu ZE, et al. 2009)

C-type lectin DC-SIGN (CD209)/

Function/ Dendritic-cell-specific intercellular adhesion molecule-3 (ICAM-3)-grabbing non-integrin (DC-SIGN) (CD209) is an important pathogen recognition receptor of the innate immune system. Recent studies showed that DC-SIGN is the major receptor of Mycobacterium tuberculosis on human dendritic cells and that polymorphisms in the DC-SIGN promoter region are associated with susceptibility to tuberculosis.

Studies/ 1- Neither promoter variants nor length variation in the neck region were associated with susceptibility to tuberculosis in Tunisian patients. (Ben-Ali M, Barreiro LB, Chabbou A et al.2007)

2- -336 G/G genotype associated with susceptibility to TB among south Indians with p=0.003 . (Selvaraj P, et al. 2009)

PTPN22 R620W polymorphism/

Function/ The PTPN22 gene encodes the lymphoid tyrosine phosphatase that has an important regulatory effect on T- and B-cell activation in immune response.

Studies/ - PTPN22 polymorphisms may have rule in susceptibility to TB in Spain (P=0.01) and Moroccan population. (Gomez LM, Anaya JM, Martin J. 2005 (Lamsyah H, Rueda B, Baassi L, et al. 2009) .

nonsynonymous polymorphisms in the NOD2 gene/

Function/ NOD2 is one of the PRRs (Pattern-recognition receptors) that contribute to the immune response to Mycobacterium tuberculosis infection.

Studies/ Three common nonsynonymous SNPs-Pro268Ser, Arg702Trp, and Ala725Gly--demonstrated significant associations with TB disease in African Americans case control study. (Austin CM, Ma X, Graviss EA. 2008) .

NITRIC OXIDE SYNTHASE 2

MACROPHAGES CONTAINING M.TBPRODUCE TNF-a &

IL-1B

NATURAL KILLER CELLS

PRODUCINGINF-g

PRODUCTION OF NITRIC OXIDE

VIANOS2

• NOS2 is encoded by polymorphic genesNOS2AAt chromosome 17q11.2-q12.• Several SNPs and microsatellite polymorphisms have

been reported in populations.

NOS2A (TAAA)10 114CASES&

Noassociation

O.R. 0.4,0.3

COLOMBIANPOPULATION

17q11.2 (CCTTT)10 304controls

association P.V.=0.0001

Gomez et/al(2007)

Vitamin D receptor

Vitamin D metabolism

Activation ofmacrophages

Restricts M.Tbgrowth

ALLELE orGENOTYPE

ASSOCIATION P.VALUE STUDY AREA

Taq 11) tt genotype2) TT genotype

1).associated withSusceptibility.2)Associated withresistance

1) p.value<0.02

2) P.value<0.02

Chennai(selvarj Pet,et al)2000

Fok1ff-genotype

susceptibility p.value=0.009 1)USA (Wilkinson,Et al 2000)2)China (Liu W, et al 2003)

VDR-SNPS Modulate the risk for TB. In west Africa.

p.Value = 0.003 Gambia (Olesen, et al 2007)

Fok1 C/TExon 2

susceptibility p.value= 0.008 Paraguay(Wilburt, et al 2007)

DISCUSSION

• Four different VDR polymorphisms have been shown(Taq1, Apa1, Bsm1 & Fok1) at chromosome 12 q12-14 in

different ethnic population studies .• After this meta-analysis description, the association of

VDR polymorphisms with susceptibility to tuberculosis Remains unproved .• Most studies conducted until now were in ethnically & geographically different populations, thus, they were Underpowered to reach any conclusions by examining The alleles separately.

• Large studies are required to determine association between VDR polymorphism & TB. worldwide.

• These studies should be with enough power to detect specific polymorphism related to TB. ,since any association will be diluted due to extended linkage disequilibrium with the specific functional allele.

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