Browsing by Author "Ahlers, Petri"

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Performance and immune characteristics of bronchoalveolar lavage by research bronchoscopy in pulmonary tuberculosis and other lung diseases in the Western Cape, South Africa
    (BMC (part of Springer Nature), 2019-06-01) Young, Carly; Ahlers, Petri; Hiemstra, Andriette M.; Loxton, Andre G.; Gutschmidt, Andrea; Malherbe, Stephanus T.; Walzl, Gerhard; Du Plessis, Nelita
    Background: Tuberculosis (TB) remains a debilitating, deadly disease that warrants innovative research tools to fully understand the pathogenesis and host immune responses, particularly at the site of infection and disease. In this regard, bronchoscopies with bronchoalveolar lavage (BAL) serve as a valuable technique for site of disease sample retrieval for further clinical- and basic research. Here we investigate the feasibility of research bronchoscopies in a low/middle-income area, where TB remains rife, and assess the value of retrieved BAL cells (BALC) for downstream fluorescent-based cellular evaluations. Methods: Using quantitative and qualitative methods, we evaluate the outcomes, safety, tolerability, participant -perception and -experience, while also providing insight into participant recruitment and screening processes of our study. Using light microscopy differential counting for BALC analysis, we evaluate the cellular composition of BAL fluid (BALF) from TB patients, healthy community controls and patients with other lung diseases. We also use flow cytometry to describe the challenges associated with fluorescence-based phenotypic analysis of autofluorescent BALC. Results: Our findings suggest that research bronchoscopies are safe, acceptable procedures for research participants and are indeed a feasible technique for future study design. We also suggest that the majority of participants are receptive to the proposition of a second research bronchoscopy. This poses an important avenue for research entailing follow-up investigations of the same study participant. Furthermore, our results show that smoking is characterized by retrieval of BALC containing particulate matter, that interferes with fluorescence-based flow cytometry data analysis. Based on light microscopy differential cell counting, our findings suggest that there are differences in the cell yields and cellular composition of the BALF between TB patients, healthy community controls and patients with other lung diseases. We also report on subject characteristics and demographic factors, namely gender and age, that have the potential to affect cell yields and cellular data of BALF. Conclusions: These findings will serve as a valuable reference for appropriate planning and design of studies involving clinical bronchoscopies for TB and lung disease research.
  • Thumbnail Image
    Item
    Prospective evaluation of host biomarkers other than interferon gamma in QuantiFERON Plus supernatants as candidates for the diagnosis of tuberculosis in symptomatic individuals
    (Elsevier, 2019-07-15) Manngo, Portia M.; Gutschmidt, Andrea; Snyders, Candice I.; Mutavhatsindi, Hygon; Manyelo, Charles M.; Makhoba, Nonjabulo S.; Ahlers, Petri; Hiemstra, Andriette; Stanley, Kim; McAnda, Shirley; Kidd, Martin; Malherbe, Stephanus T.; Walzl, Gerhard; Chegou, Novel N.
    Background: There is an urgent need for new tools for the diagnosis of TB. We evaluated the usefulness recently described host biomarkers in supernatants from the newest generation of the QuantiFERON test (QuantiFERON Plus) as tools for the diagnosis of active TB. Methods: We recruited individuals presenting at primary health care clinics in Cape Town, South Africa with symptoms requiring investigation for TB disease, prior to the establishment of a clinical diagnosis. Participants were later classified as TB or other respiratory diseases (ORD) based on the results of clinical and laboratory tests. Using a multiplex platform, we evaluated the concentrations of 37 host biomarkers in QuantiFERON Plus supernatants from study participants as tools for the diagnosis of TB. Results: Out of 120 study participants, 35(29.2%) were diagnosed with active TB, 69(57.5%) with ORD whereas 16(13.3%) were excluded. 14(11.6%) of the study participants were HIV infected. Although individ- ual host markers showed potential as diagnostic candidates, the main finding of the study was the identi- fication of a six-marker biosignature in unstimulated supernatants (Apo-ACIII, CXCL1, CXCL9, CCL8, CCL-1, CD56) which diagnosed TB with sensitivity and specificity of 73.9%(95% CI; 51.6–87.8) and 87.6%(95% CI; 77.2–94.5), respectively, after leave-one-out cross validation. Combinations between TB-antigen specific biomarkers also showed potential (sensitivity of 77.3% and specificity of 69.2%, respectively), with multi- ple biomarkers being significantly different between TB patients, Quantiferon Plus Positive and Quantif- eron Plus negative individuals with ORD, regardless of HIV status. Conclusions: Biomarkers detected in QuantiFERON Plus supernatants may contribute to adjunctive diag- nosis of TB.
  • Thumbnail Image
    Item
    A semi-automatic technique to quantify complex tuberculous lung lesions on 18F-fluorodeoxyglucose positron emission tomography/computerised tomography images
    (Springer Open, 2018-06-25) Malherbe, Stephanus T.; Dupont, Patrick; Kant, Ilse; Ahlers, Petri; Kriel, Magdalena; Loxton, Andre G.; Chen, Ray Y.; Via, Laura E.; Thienemann, Friedrich; Wilkinson, Robert J; Barry, Clifton E.; Griffith-Richards, Stephanie; Ellman, Annare; Ronacher, Katharina; Winter, Jill; Walzl, Gerhard; Warwick, James M.
    Background: There is a growing interest in the use of 18F-FDG PET-CT to monitor tuberculosis (TB) treatment response. However, TB causes complex and widespread pathology, which is challenging to segment and quantify in a reproducible manner. To address this, we developed a technique to standardise uptake (Z-score), segment and quantify tuberculous lung lesions on PET and CT concurrently, in order to track changes over time. We used open source tools and created a MATLAB script. The technique was optimised on a training set of five pulmonary tuberculosis (PTB) cases after standard TB therapy and 15 control patients with lesion-free lungs. Results: We compared the proposed method to a fixed threshold (SUV > 1) and manual segmentation by two readers and piloted the technique successfully on scans of five control patients and five PTB cases (four cured and one failed treatment case), at diagnosis and after 1 and 6 months of treatment. There was a better correlation between the Z-score-based segmentation and manual segmentation than SUV > 1 and manual segmentation in terms of overall spatial overlap (measured in Dice similarity coefficient) and specificity (1 minus false positive volume fraction). However, SUV > 1 segmentation appeared more sensitive. Both the Z-score and SUV > 1 showed very low variability when measuring change over time. In addition, total glycolytic activity, calculated using segmentation by Z-score and lesion-to-background ratio, correlated well with traditional total glycolytic activity calculations. The technique quantified various PET and CT parameters, including the total glycolytic activity index, metabolic lesion volume, lesion volumes at different CT densities and combined PET and CT parameters. The quantified metrics showed a marked decrease in the cured cases, with changes already apparent at month one, but remained largely unchanged in the failed treatment case. Conclusions: Our technique is promising to segment and quantify the lung scans of pulmonary tuberculosis patients in a semi-automatic manner, appropriate for measuring treatment response. Further validation is required in larger cohorts.