Thesis (PhD)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: The immune response against M. tuberculosis is multifactorial, involving a network of innate
and adaptive immune responses. Characterization of the immune response, a clear
understanding of the dynamics and interplay of different arms of the immune response and
the identification of infection-stage specific biomarkers are critical to allow the
development of better tools for combating tuberculosis. In an attempt to identify such
biomarkers, we studied pulmonary tuberculosis patients and their contacts in Addis Ababa,
Ethiopia as part of EDCTP and BMGF funded tuberculosis projects by using multiplex
techniques. We analysed 45 genes using the Multiplex Ligation Dependent Probe
Amplification (MLPA) technique and the expression of IL-4δ2, BLR1, MARCO, CCL-19, IL7R, Bcl2, FcyR1A, MMP9, and LTF genes discriminate TB cases from their healthy contacts.
FoxP3, TGFß1 and CCL-19 discriminate latently infected from uninfected contacts. Single
genes predict with an area under the Receiver Operating Characteristic (ROC) curve of 0.68
to 0.85 while a combination of genes identified up to 95% of the different groups. Similarly,
the multiplex analysis of cytokines and chemokines also showed that single or combinations
of plasma cytokines and chemokines discriminate between different clinical groups
accurately. The median plasma level of EGF, fractalkine, IFN-y, IL-4, MCP-3 and IP-10 is
significantly different (p<0.05) in active tuberculosis and non active tuberculosis infection
and the median plasma levels of IFN-y, IL-4, MCP-3, MIP-1ß and IP-10 were significantly
different (p<0.05) before and after treatment. We also found a significant difference
(p<0.05) in plasma levels of cytokines of patients infected with the different lineages and
different families of the modern lineage. The plasma level of IL-4 was significantly higher in
patients infected with lineage 3 (p<0.05) as compared to lineage 4 and the CAS familyinfected
patients had a higher plasma level of IL-4 (P<0.05) as compared to patients infected
with H and T families but there was no difference between H and T families.
We identified genes and cytokines which had been reported from other studies in different
settings and we believe that these molecules are very promising biomarkers for classifying
active tuberculosis, latent infection, absence of infection and treated infection. These
markers may be suitable for the development of clinically useful tools but require further
validation and qualification in different populations and in larger studies. / AFRIKAANSE OPSOMMING: Die immuunrespons teen M. tuberculosis is multifaktoriaal en betrek ‘n netwerk van niespesifieke
and spesifieke immuunresponse. Karakterisering van die immuunrespons, ‘n
duidelike insig in die dinamika en tussenspel deur die verskillende arms van die
immuunrespons en die identifikasie van spesifieke biomerkers is krities belangrik om die
ontwikkeling van nuwe hulpmiddels teen tuberkulose te bevorder. In ‘n poging om sulke
biomerkers te identifiseer het ons pulmonale tuberkulose pasiënte en hulle kontakte in
Addis Ababa, Etiopië, as deel van die EDCTP en BMGF befondste tuberkulose projekte
bestudeer met multipleks tegnieke. Ons het 45 gene analiseer met ‘Multiplex Ligation
Dependent Probe Amplification (MLPA)’ en gevind dat die geenuitdrukking van IL-4•2, BLR1,
MARCO, CCL-19, IL7R, Bcl2, Fc•R1A, MMP9, en LTF TB pasiënte van hulle kontakte
onderskei. FoxP3, TGF•1 en CCL-19 onderskei tussen latent infekteerde en ongeïnfekteerde
kontakte. Enkele gene voorspel met ‘n area onder die ‘Receiver Operating Characteristic
(ROC)’ kurwe van 0.68 tot 0.85 terwyl die kombinasie van gene 95% van die verskillende
groepe identifiseer. Soortgelyk het multipleks analise van sitokiene en chemokiene
verskillende kliniese groepe akkuraat van mekaar onderskei. Die mediane plasmavlakke van
EGF, fractalkine, IFN-•, IL-4, MCP-3 en IP-10 is beduidend verskillend (p<0.05) in aktiewe
tuberkulose en nie-aktiewe tuberkulose infeksie en die mediane plasmavlak van IFN-•, IL-4,
MCP-3, MIP-1• en IP-10 was beduidend verskillend voor en na behandeling. Ons het ook
beduidende verskille (p<0.05) in plasmavlakke van sitokiene in pasiënte gevind wat
infekteer is met verskillende stamme and verskillende families van die moderne stamme.
Die plasmavlak van IL-4 was beduidend hoër in pasiënte wat infekteer is met stam 3
(p<0.05) teenoor stam 4 en die CAS familie-infekteerde pasiënte het ‘n hoër plasmavlak van
IL-4 (p<0.05) teenoor pasiënte met H en T familie infeksie hoewel daar geen versikke was
tussen die H en T families nie. Ons het gene en sitokiene identifiseer wat deur ander werkers onder verskillende
omstandighede ook beskryf is en ons glo dat hierdie molekules baie belowende biomerkers
is om aktiewe tuberkulose, latent tuberkulose, die afwesigheid van infeksie en behandelde
infeksie van mekaar te onderskei. Hierdie merkers mag toepaslik wees vir die ontwikkeling
van bruikbare kliniese hulpmiddele maar benodig verdere validasie en kwalifikasie in
verskillende populasiegroepe en in groter studies. / Bill and Melinda Gates Foundation (BMGF) / European and Developing Countries Clinical Trials Partnership (EDCTP) / African European Tuberculosis Consortium (AE TBC).
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/71942 |
| Date | 03 1900 |
| Creators | Bekele, Adane Mihret |
| Contributors | Walzl, Gerhard, Howe, Rawleigh, Aseffa, Abraham, Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Biomedical Sciences. Division Molecular Biology and Human Genetics. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | xi, 161 p. : col. ill. |
| Rights | Stellenbosch University |
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