Henry C Mwandumba

University of Malawi, Zomba, Southern Region, Malawi

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Publications (18)98.68 Total impact

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    ABSTRACT: In HIV-uninfected adults with pulmonary tuberculosis (TB), anti-TB treatment is associated with changes in Mycobacterium tuberculosis (Mtb)-specific immune responses, which correlate with sputum bacillary load. It is unclear if this occurs in HIV-infected TB patients. We investigated changes in Mtb-specific immune responses and sputum bacillary clearance during anti-TB treatment in HIV-infected and HIV-uninfected adults with pulmonary TB. Sputum bacillary load was assessed by smear microscopy and culture. Mtb-specific IFN-γ secreting peripheral blood mononuclear cells were enumerated using an ELISPOT assay following stimulation with PPD, ESAT-6 and CFP-10. The baseline frequency of Mtb-specific IFN-γ secreting cells was lower in HIV-infected than HIV-uninfected patients (median PPD 32 vs. 104 Spot Forming Units (SFU), p = 0.05; CFP-10 19 vs. 74 SFU, p = 0.01). ESAT-6-specific IFN-γ secreting cells and sputum bacillary load declined progressively during treatment in both HIV-infected and HIV-uninfected patients. HIV infection did not influence the 2-month sputum culture conversion rate (Odds Ratio 0.89, p = 0.95). These findings suggest that changes in ESAT-6-specific immune responses during anti-TB treatment correspond with changes in sputum bacillary load irrespective of host HIV infection status. The utility of Mtb-specific IFN-γ responses as a proxy measure of treatment response in HIV-infected TB patients warrants further evaluation in other settings. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.
    Tuberculosis (Edinburgh, Scotland) 05/2015; 190. DOI:10.1016/j.tube.2015.05.009 · 3.50 Impact Factor
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    ABSTRACT: Background. Antibiotic tolerant bacterial persistence prevents treatment shortening in drug susceptible tuberculosis (TB) and accumulation of intracellular lipid bodies has been proposed to identify a persister phenotype of Mycobacterium tuberculosis cells. In Malawi, we modelled Bacillary Elimination Rates (BERs) from sputum cultures and calculated the percentage of lipid body positive acid fast bacilli (%LB+AFB) on sputum smears. We assessed whether these putative measurements of persistence predict unfavourable outcomes (treatment failure/relapse). Methods. Adults with pulmonary TB received standard 6 month therapy. Sputum samples were collected during the first 8 weeks for Serial Sputum Colony Counting (SSCC) on agar and Time to Positivity (TTP) measurement in BACTEC MGIT broth. BERs were extracted from non-linear and linear mixed effects models fitted respectively to these datasets. %LB+AFB counts were assessed by fluorescence microscopy. Patients were followed until one year post-treatment. Individual BERs and %LB+AFB counts were related to final outcomes. Results. 133 patients (56% HIV co-infected) participated and 15 unfavourable outcomes were reported. These were inversely associated with faster sterilisation phase bacillary elimination from the SSCC model (Odds Ratio [OR]: 0.39, 95% Confidence interval [CI]: 0.22-0.70) and a faster BER from the TTP model (OR: 0.71, 95% CI: 0.55-0.94). Higher %LB+AFB counts on day 21-28 were recorded in patients who suffered unfavourable final outcomes compared to those who achieved stable cure (p=0.008). Conclusions. Modelling BERs predicts final outcome and high %LB+AFB counts 3-4 weeks into therapy may identify a persister bacterial phenotype. These methods deserve further evaluation as surrogate endpoints for clinical trials.
    Clinical Infectious Diseases 03/2015; 61(1). DOI:10.1093/cid/civ195 · 9.42 Impact Factor
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    ABSTRACT: Background. HIV-infected persons on antiretroviral therapy (ART) remain at higher risk of pulmonary tuberculosis (TB) than HIV-uninfected individuals. This increased susceptibility may be due to impairment of alveolar macrophage (AM) function and/or mycobacteria-specific alveolar CD4+ T cell responses observed in HIV-infected ART-naive adults. Methods. Peripheral blood was drawn and bronchoalveolar lavage (BAL) performed on healthy, 35 HIV-uninfected, 25 HIV-infected ART-naive and 50 HIV-infected ART-treated asymptomatic adults. Phagosomal proteolysis of AM was assessed with fluorogenic beads. Mycobacteria-specific CD4+ T cell responses were measured by intracellular cytokine staining. Results. HIV-infected adults on ART exhibited lower plasma HIV viral load and higher blood CD4+ T cell count than ART-naïve adults. AM proteolysis and total mycobacteria-specific Th1 CD4+ T cell responses in individuals on ART for ≥4 years were similar to HIV-uninfected controls but those on ART for <4 years had impaired responses. Total Influenza-specific alveolar Th1 CD4+ T cell responses were intact in all individuals receiving ART. In contrast, BAL and blood mycobacteria-specific polyfunctional CD4+ T cell responses were impaired in adults on ART irrespective of duration. Conclusion. AM and mycobacteria-specific alveolar CD4+ T cell responses in HIV-infected adults on ART for <4 years are impaired and may partly explain the high risk of TB in HIV-infected individuals on ART. Strategies to augment ART to improve lung immune cell function and reduce the high incidence of TB in HIV-infected adults who initiate ART should be investigated.
    American Journal of Respiratory and Critical Care Medicine 09/2014; 190(8). DOI:10.1164/rccm.201405-0864OC · 11.99 Impact Factor
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    ABSTRACT: HIV-1-infected persons are at higher risk of lower respiratory tract infections than HIV-1-uninfected individuals. This suggests strongly that HIV-infected persons have specific impairment of pulmonary immune responses, but current understanding of how HIV alters pulmonary immunity is incomplete. Alveolar macrophages (AMs), comprising small and large macrophages, are major effectors of innate immunity in the lung. We postulated that HIV-1 impairs pulmonary innate immunity through impairment of AM physiological functions. AMs were obtained by bronchoalveolar lavage from healthy, asymptomatic, antiretroviral therapy-naive HIV-1-infected and HIV-1-uninfected adults. We used novel assays to detect in vivo HIV-infected AMs and to assess AM functions based on the HIV infection status of individual cells. We show that HIV has differential effects on key AM physiological functions, whereby small AMs are infected preferentially by the virus, resulting in selective impairment of phagocytic function. In contrast, HIV has a more generalized effect on AM proteolysis, which does not require direct viral infection. These findings provide new insights into how HIV alters pulmonary innate immunity and the phenotype of AMs that harbors the virus. They underscore the need to clear this HIV reservoir to improve pulmonary immunity and reduce the high incidence of lower respiratory tract infections in HIV-1-infected individuals.Mucosal Immunology advance online publication, 29 January 2014; doi:10.1038/mi.2013.127.
    Mucosal Immunology 01/2014; 7(5). DOI:10.1038/mi.2013.127 · 7.54 Impact Factor
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    ABSTRACT: Much of the activity of the macrophage as an effector cell is performed within its phagocytic compartment. This ranges from the degradation of tissue debris as part of its homeostatic function to the generation of the superoxide burst as part of its microbicidal response to infection. We have developed a range of real-time readouts of phagosomal function that enable these activities to be rigorously quantified. This unit contains descriptions of several of these assays assessed by different methods of quantitation, including a fluorescence resonance emission transfer (FRET) assay for phagosome/lysosome fusion measured by spectrofluorometry, a fluorogenic assay for the superoxide burst measured by flow cytometry, and a fluorogenic assay for bulk proteolysis measured by confocal microscopy. These assays illustrate both the range of parameters that can be quantified and the flexibility of instrumentation that can be exploited for their quantitation. Curr. Protoc. Immunol. 102:14.34.1-14.34.14. © 2013 by John Wiley & Sons, Inc.
    Current protocols in immunology / edited by John E. Coligan ... [et al.] 01/2013; 102:14.34.1-14.34.14. DOI:10.1002/0471142735.im1434s102
  • Gut 05/2012; 61(Suppl 2):A12-A12. DOI:10.1136/gutjnl-2012-302514a.28 · 13.32 Impact Factor
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    ABSTRACT: Serial Sputum Colony Counting (SSCC) is an important technique in clinical trials of new treatments for tuberculosis (TB). Quantitative cultures on selective Middlebrook agar are used to calculate the rate of bacillary elimination from sputum collected from patients at different time points during the first 2 months of therapy. However, the procedure can be complicated by high sample contamination rates. This study, conducted in a resource-poor setting in Malawi, assessed the ability of different antifungal drugs in selective agar to reduce contamination. Overall, 229 samples were studied and 15% to 27% were contaminated. Fungal organisms were particularly implicated, and samples collected later in treatment were at particular risk (P < 0.001). Amphotericin B (AmB) is the standard antifungal drug used on SSCC plates at a concentration of 10 mg/ml. On selective Middlebrook 7H10 plates, AmB at 30 mg/ml reduced sample contamination by 17% compared with AmB at 10 mg/ml. The relative risk of contamination using AmB at 10 mg/ml was 1.79 (95% confidence interval [CI], 1.25 to 3.55). On Middlebrook 7H11 plates, a combination of AmB at 10 mg/ml and carbendazim at 50 mg/ml was associated with 10% less contamination than AmB at 30 mg/ml. The relative risk of contamination with AmB at 30 mg/ml was 1.79 (95% CI, 1.01 to 3.17). Improved antifungal activity was accompanied by a small reduction in bacillary counts, but this did not affect modeling of bacillary elimination. In conclusion, a combination of AmB and carbendazim optimized the antifungal activity of selective media for growth of TB. We recommend this method to reduce contamination rates and improve SSCC studies in African countries where the burden of TB is highest.
    Journal of clinical microbiology 05/2012; 50(7):2315-20. DOI:10.1128/JCM.00043-12 · 4.23 Impact Factor
  • The Journal of neuropsychiatry and clinical neurosciences 06/2011; 23(2):E32-4. DOI:10.1176/appi.neuropsych.23.2.E32 · 2.77 Impact Factor
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    Chest 07/2010; 138(1):234-5. DOI:10.1378/chest.10-0077 · 7.13 Impact Factor
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    ABSTRACT: Professional phagocytes ingest particulate material to fulfil a diverse array of functions in a multicellular organism. The ancestral function of phagosomes is digestion; however, through evolution this degradative capacity has become pivotal to the adaptive immune response by processing antigens to be presented to lymphocytes. Moreover, phagocytes have also acquired an active role in microbial killing. This Innovation article describes new assays that probe the biological activities which occur within phagosomes. These assays provide functional insights into how the phagosome fulfils its diverse roles in homeostasis and in innate and adaptive immune responses.
    Nature Reviews Immunology 09/2009; 9(8):594-600. DOI:10.1038/nri2591
  • Henry C Mwandumba
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    ABSTRACT: Malawi is one of many developing countries conducting research in collaboration with developed countries. These partnerships have facilitated the sharing of ideas, knowledge, technology and resources, as well as developing and strengthening the country's research capacity. Professor Malcolm Molyneux, who recently retired as director of the Malawi-Liverpool-Wellcome Trust (MLW) clinical research programme, the Wellcome Trust's major overseas programme in Malawi, played a substantial role in developing Malawi's capacity to conduct relevant and competitive clinical research by encouraging and promoting collaboration between clinicians, researchers and sponsors from within Malawi and abroad. Not only have these developments resulted in better patient care in Malawi and beyond, they have also advanced understanding of the epidemiology, pathogenesis and treatment of important communicable diseases. This paper discusses Malcolm Molyneux's remarkable contribution to research capacity development in Malawi.
    Transactions of the Royal Society of Tropical Medicine and Hygiene 03/2009; 103 Suppl 1:S19-22. DOI:10.1016/j.trstmh.2009.01.017 · 1.93 Impact Factor
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    ABSTRACT: Nucleic acid amplification tests (NAAT) based on PCR provide rapid identification of Mycobacterium tuberculosis and the detection of rifampicin resistance. Indications for their use in clinical samples are now included in British tuberculosis guidelines. A retrospective audit of patients with suspected mycobacterial infection in a Liverpool hospital between 2002 and 2006. Documentation of the impact of NAAT usage in acid fast bacillus (AFB) microscopy positive samples on clinical practice and the influence of a multidisciplinary group on their appropriate use, compared with British guidelines. Mycobacteria were seen or isolated from 282 patients and identified as M tuberculosis in 181 (64%). NAAT were indicated in 87/123 AFB positive samples and performed in 51 (59%). M tuberculosis was confirmed or excluded by this method in 86% of tested samples within 2 weeks, compared with 7% identified using standard methods. The appropriate use of NAAT increased significantly over the study period. The NAAT result had a clinical impact in 20/51 (39%) tested patients. Culture results suggest the potential for a direct clinical impact in 8/36 (22%) patients in which it was indicated but not sent and 5/36 (14%) patients for whom it was not indicated. Patients managed by the multidisciplinary group had a higher rate of HIV testing and appropriate use of NAAT. There were significant clinical benefits from the use of nucleic acid amplification tests in this low prevalence setting. Our data suggest that there would be additional benefit from their use with all AFB smear positive clinical samples.
    Thorax 05/2008; 63(4):317-21. DOI:10.1136/thx.2007.083816 · 8.56 Impact Factor
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    ABSTRACT: In the developing world, early mortality within 1 month of commencing tuberculosis (TB) treatment is high, particularly with human immunodeficiency virus (HIV) co-infection. In Malawi, 40% of those who die do so in the first month of treatment. Reasons remain unclear and may include delayed diagnosis, opportunistic infections, immune restoration inflammatory syndrome (IRIS) or malnutrition. One possible contributing factor is underlying hypoadrenalism associated with TB-HIV, exacerbated by rifampicin (RMP) induction of P450 and glucocorticoid metabolism. To assess the prevalence of hypoadrenalism in TB patients before and after commencement of TB treatment, and relationship with early mortality. Prospective descriptive study assessing hypoadrenalism before and after anti-tuberculosis treatment, HIV status and outcome up to 3 months post-treatment. Of 51 patients enrolled, 29 (56.9%) were female (median age 32 years, range 18-62). Of 43 patients HIV-tested, 38 (88.3%) were HIV-positive and 15.7% died within the first month. At 3 months, 11 (21.6%) were known to have died. Adequate cortisol levels were found in 49/51 (95.9%) before commencing RMP. Neither of the two with reduced response died. All 34 patients revealed adequate cortisol responses at 2 weeks. No evidence of hypoadrenalism was found in this first study to assess adrenal function and outcome of anti-tuberculosis treatment.
    The International Journal of Tuberculosis and Lung Disease 04/2008; 12(3):314-8. · 2.76 Impact Factor
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    ABSTRACT: Infection with human immunodeficiency virus (HIV) may affect the clinical presentation of pulmonary tuberculosis (TB). To investigate the association between sputum smear status at presentation and local pulmonary immune responses in HIV-infected patients with pulmonary TB, we compared the cellular and cytokine profiles in bronchoalveolar lavage (BAL) fluid obtained from the site of lung disease in 22 sputum smear- and culture-positive, and 17 sputum smear-negative but culture-positive pulmonary TB patients. Smear-positive patients had significantly higher BAL fluid concentrations of IL-6 (p=0.007), IL-8 (p=0.02), IL-10 (p=0.03) and IFN-gamma (p=0.008) than smear-negative patients. No significant differences in the proportions of examined BAL cells were found. We concluded that sputum smear-positive TB was associated with greater pro-inflammatory and immunomodulatory cytokine responses at the site of lung disease than sputum smear-negative disease. The local immune responses may affect the clinical presentation of active pulmonary TB in HIV-infected patients.
    Tuberculosis 02/2008; 88(1):58-63. DOI:10.1016/j.tube.2007.06.003 · 3.50 Impact Factor
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    ABSTRACT: The functional capacity of alveolar macrophages (AM) in human immunodeficiency virus (HIV)-infected patients with pulmonary tuberculosis (TB) is not completely understood. To investigate the capacity of AM to mediate inflammatory responses, we obtained AM from human subjects by bronchoalveolar lavage (BAL) and studied the cells ex vivo. We compared AM from HIV-infected patients with suspected pulmonary TB to AM from healthy, HIV-negative controls for their capacity to produce TNF-alpha or IL-6 spontaneously and upon stimulation with lipopolysaccharide (LPS). Cytokine-producing cells were identified by macrophage markers and intracellular cytokine staining and flow cytometry. A higher proportion of AM from patients with microbiologically confirmed pulmonary TB than patients with probable TB or controls spontaneously expressed TNF-alpha shortly after isolation (geometric means: 38.5%, 23.7% and 15.8%, respectively), suggesting endogenous cytokine production. The proportions of AM spontaneously expressing TNF-alpha positively correlated with peripheral blood CD4(+) T-lymphocyte counts in patients (partial r=0.60, p=0.003) but not controls. Stimulation with LPS resulted in a significant increase in the proportions of TNF-alpha- and IL-6-positive AM from patients and controls (p<0.01). Bronchoalveolar lavage fluid (BALF) from confirmed TB patients also contained higher concentrations of the inflammatory cytokines predominantly produced by macrophages, IL-6 and IL-8, than controls (geometric mean cytokine concentrations per gram of BALF albumin were 1291 pg/g vs. 115 pg/g, p=0.03 for IL-6 and 4739 pg/g vs. 704 pg/g, p=0.03 for IL-8). We concluded that AM from HIV-infected patients with pulmonary TB produced and released inflammatory cytokines in vivo and retained their innate ability to respond to stimulation by LPS.
    Microbes and Infection 08/2007; 9(9):1053-60. DOI:10.1016/j.micinf.2007.04.013 · 2.73 Impact Factor
  • International Journal of Antimicrobial Agents 03/2007; 29. DOI:10.1016/S0924-8579(07)71454-1 · 4.26 Impact Factor
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    ABSTRACT: Alveolar macrophages (AM) are the first professional phagocytes encountered by aerosols containing infections in the lungs, and their phagocytic capacity may be affected by these infections or environmental particles. The aim of this study was to evaluate the innate endocytic and phagocytic properties of human AM obtained from patients with pulmonary tuberculosis and to characterize the vacuoles in which Mycobacterium tuberculosis bacilli reside in vivo. AM were obtained by bronchoalveolar lavage from patients with suspected tuberculosis and from asymptomatic volunteers (controls). Clinical case definitions were based on mycobacterial culture of respiratory specimens and HIV serology. To assess phagocytosis, endocytosis, and acidification of the endosomal system, AM were cultured with IgG-coated polystyrene beads, dextran, and a pH-sensitive reporter (3-(2,4-dinitroanilino)-3-amino-N-methyldipropylamine) and were evaluated by light and immunoelectron microscopy. Cells from 89 patients and 10 controls were studied. We found no significant difference between the two groups in the ability of AM either to ingest beads and dextran or to deliver them to acidified lysosomes. In AM from patients with tuberculosis, the bacilli were located in vacuoles that failed to accumulate endocytosed material and were not acidified. We concluded that AM from patients with tuberculosis and HIV infections were competent to endocytose and phagocytose material and to deliver the material to functional, acidified lysosomes. M. tuberculosis residing in these AM arrests the progression of their phagosomes, which fail to fuse with acidified lysosomes. This confirms, for the first time in humans with tuberculosis and HIV, the conclusions from previous animal and in vitro studies.
    The Journal of Immunology 05/2004; 172(7):4592-8. DOI:10.4049/jimmunol.172.7.4592 · 5.36 Impact Factor
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    David G Russell, Henry C Mwandumba, Elizabeth E Rhoades
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    ABSTRACT: Pathogenic Mycobacterium reside inside vacuoles in their host macrophages. These vacuoles fail to fuse with lysosomes yet interact with early endosomes. Glycoconjugates released by the intracellular bacilli traffic through the host cell and are released through exocytosis. These molecules represent both antigens for immune recognition and modulators of immune function. The molecules play key roles in the induction and maintenance of the granuloma, a tissue response that limits bacterial spread yet ensures persistence of the infection.
    The Journal of Cell Biology 09/2002; 158(3):421-6. DOI:10.1083/jcb.200205034 · 9.69 Impact Factor

Publication Stats

245 Citations
98.68 Total Impact Points

Institutions

  • 2015
    • University of Malawi
      • College of Medicine
      Zomba, Southern Region, Malawi
  • 2009–2014
    • University of Liverpool
      • • Department of Clinical Sciences
      • • Institute of Infection & Global Health
      Liverpool, England, United Kingdom
  • 2004–2014
    • Liverpool School of Tropical Medicine
      • • Department of Clinical Sciences
      • • Clinical Research Group
      Liverpool, England, United Kingdom
  • 2012
    • The Queen Elizabeth Central Hospital in Blantyre
      Kapeni, Southern Region, Malawi
  • 2008
    • Royal Liverpool and Broadgreen University Hospitals NHS Trust
      Liverpool, England, United Kingdom
  • 2007
    • Malawi-Liverpool-Wellcome Trust Clinical Research Programme
      Kapeni, Southern Region, Malawi