Browsing by Author "Bekele, Yonas"

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    Africa-wide evaluation of host biomarkers in QuantiFERON supernatants for the diagnosis of pulmonary tuberculosis
    (Nature Research, 2018-02-08) Chegou, Novel N.; Sutherland, Jayne S.; Namuganga, Anna-Ritah; Corstjens, Paul L. A. M.; Geluk, Annemieke; Gebremichael, Gebremedhin; Mendy, Joseph; Malherbe, Stephanus; Stanley, Kim; Van Der Spuy, Gian D.; Kriel, Magdalena; Loxton, Andre G.; Kriel, Belinda; Simukonda, Felanji; Bekele, Yonas; Sheehama, Jacob A.; Nelongo, Josefina; Van Der Vyver, Marieta; Gebrexabher, Atsbeha; Hailu, Habteyes; Esterhuyse, Maria M.; Rosenkrands, Ida; Aagard, Claus; Kidd, Martin; Kassa, Desta; Mihret, Adane; Howe, Rawleigh; Cliff, Jacqueline M.; Crampin, Amelia C.; Mayanja-Kizza, Harriet; Kaufmann, Stefan H. E.; Dockrell, Hazel M.; Ottenhoff, Tom H. M.; Walzl, Gerhard; AE-TBC consortium
    We investigated host-derived biomarkers that were previously identified in QuantiFERON supernatants, in a large pan-African study. We recruited individuals presenting with symptoms of pulmonary TB at seven peripheral healthcare facilities in six African countries, prior to assessment for TB disease. We then evaluated the concentrations of 12 biomarkers in stored QuantiFERON supernatants using the Luminex platform. Based on laboratory, clinical and radiological findings and a pre-established algorithm, participants were classified as TB disease or other respiratory diseases(ORD). Of the 514 individuals included in the study, 179(34.8%) had TB disease, 274(51.5%) had ORD and 61(11.5%) had an uncertain diagnosis. A biosignature comprising unstimulated IFN-γ, MIP-1β, TGF-α and antigen-specific levels of TGF-α and VEGF, identified on a training sample set (n = 311), validated by diagnosing TB disease in the test set (n = 134) with an AUC of 0.81(95% CI, 0.76–0.86), corresponding to a sensitivity of 64.2%(95% CI, 49.7–76.5%) and specificity of 82.7%(95% CI, 72.4–89.9%). Host biomarkers detected in QuantiFERON supernatants can contribute to the diagnosis of active TB disease amongst people presenting with symptoms requiring investigation for TB disease, regardless of HIV status or ethnicity in Africa.
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    Combination of gene expression patterns in whole blood discriminate between tuberculosis infection states
    (BioMed Central, 2014-05) Mihret, Adane; Loxton, Andre G.; Bekele, Yonas; Kaufmann, Stefan H. E.; Kidd, Martin; Haks, Marielle C.; Ottenhoff, Tom H. M.; Aseffa, Abraham; Howe, Rawleigh; Walzl, Gerhard
    Background Genetic factors are involved in susceptibility or protection to tuberculosis (TB). Apart from gene polymorphisms and mutations, changes in levels of gene expression, induced by non-genetic factors, may also determine whether individuals progress to active TB. Methods We analysed the expression level of 45 genes in a total of 47 individuals (23 healthy household contacts and 24 new smear-positive pulmonary TB patients) in Addis Ababa using a dual colour multiplex ligation-dependent probe amplification (dcRT-MLPA) technique to assess gene expression profiles that may be used to distinguish TB cases and their contacts and also latently infected (LTBI) and uninfected household contacts. Results The gene expression level of BLR1, Bcl2, IL4d2, IL7R, FCGR1A, MARCO, MMP9, CCL19, and LTF had significant discriminatory power between sputum smear-positive TB cases and household contacts, with AUCs of 0.84, 0.81, 0.79, 0.79, 0.78, 0.76, 0.75, 0.75 and 0.68 respectively. The combination of Bcl2, BLR1, FCGR1A, IL4d2 and MARCO identified 91.66% of active TB cases and 95.65% of household contacts without active TB. The expression of CCL19, TGFB1, and Foxp3 showed significant difference between LTBI and uninfected contacts, with AUCs of 0.85, 0.82, and 0.75, respectively, whereas the combination of BPI, CCL19, FoxP3, FPR1 and TGFB1 identified 90.9% of QFT- and 91.6% of QFT+ household contacts. Conclusions Expression of single and especially combinations of host genes can accurately differentiate between active TB cases and healthy individuals as well as between LTBI and uninfected contacts.
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    Impact of HIV co-infection on plasma level of cytokines and chemokines of pulmonary tuberculosis patients
    (BioMed Central, 2014-03-04) Mihret, Adane; Abebe, Markos; Bekele, Yonas; Aseffa, Abraham; Walzl, Gerhard; Howe, Rawleigh
    Background The immunologic environment during HIV/M. tuberculosis co-infection is characterized by cytokine and chemokine irregularities that have been shown to increase immune activation, viral replication, and T cell dysfunction. Methods We analysed ex vivo plasma samples from 17 HIV negative and 16 HIV pulmonary tuberculosis co infected cases using Luminex assay to see impact of HIV co-infection on plasma level of cytokines and chemokines of pulmonary tuberculosis patients before and after anti Tuberculosis treatment. Results The median plasma level of IFN-γ, IL-4, MCP-3, MIP-1β and IP-10 was significantly different (P < 0.05) before and after treatment in HIV negative TB patients but not in HIV positive TB patients. There was no significant difference between HIV positive and HIV negative TB patients (P > 0.05) in the plasma level of any of the cytokines or chemokines before treatment and anti TB treatment did not change the level of any of the measured cytokines in HIV positive tuberculosis patients. The ratio of IFN-γ/IL-10 and IFN-γ/IL-4 showed a significant increase after treatment in HIV negative TB cases but not in HIV positive TB cases which might indicate prolonged impairment of immune response to TB in HIV positive TB patients as compared to HIV negative tuberculosis patients. Conclusions HIV positive and HIV negative Tuberculosis patients display similar plasma cytokine and chemokine pattern. However, anti TB treatment significantly improves the Th1 cytokines and level of chemokines but does not restore the immune response in HIV positive individuals.