Impact of selective immune-cell depletion on growth of Mycobacterium tuberculosis (Mtb) in a whole-blood bactericidal activity (WBA) assay

Cross, Gail Brenda; Yeo, Benjamin Chaik Meng; Hutchinson, Paul; Tan, Mark C.; Verma, Rupangi; Lu, Qing; Paton, Nicholas I.

doi:10.1371/journal.pone.0216616

Cited by 5 publications

(3 citation statements)

References 35 publications

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“…More definitive transcriptome changes were seen in a previous study with drug exposure in broth cultures [3], and it is possible that the additional presence of immune cells in the WBA paradigm modifies the response to drugs. We have demonstrated that neutrophils significantly alter the bactericidal activity of rifampicin in the WBA paradigm, possibly by intracellular bacterial sequestration [28]. In an ex vivo cellular model, the response to drugs was more characteristic of host responses than of specific effects on the primary drug targets [4].…”

Section: Discussionmentioning

confidence: 91%

Gene expression responses to anti-tuberculous drugs in a whole blood model

et al. 2020

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Background: There is a need for better tools to evaluate new or repurposed TB drugs. The whole blood bactericidal activity (WBA) assay has been advocated for this purpose. We investigated whether transcriptional responses in the WBA assay resemble TB responses in vivo, and whether the approach might additionally reveal mechanisms of action. Results: 1422 of 1798 (79%) of differentially expressed genes in WBA incubated with the standard combination of rifampicin, isoniazid, pyrazinamide and ethambutol were also expressed in sputum (P < 0.0001) obtained from patients taking the same combination of drugs; these comprised well-established treatment-response genes. Gene expression profiles in WBA incubated with the standard drugs individually, or with moxifloxacin or faropenem (with amoxicillin and clavulanic acid) clustered by individual drug exposure. Distinct pathways were detected for individual drugs, although only with isoniazid did these relate to known mechanisms of drug action. Conclusions: Substantial agreement between whole blood cultures and sputum and the ability to differentiate individual drugs suggest that transcriptomics may add value to the whole blood assay for evaluating new TB drugs.

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Section: Discussionmentioning

confidence: 91%

Gene expression responses to anti-tuberculous drugs in a whole blood model

et al. 2020

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“…Cross et al. reported that the rate of M.tb growth was increased in monocyte-depleted and CD66b+ neutrophil-depleted compared to un-depleted whole blood, although the inverse was true in the presence of rifampicin ( 107 ). In the O’Shea et al.…”

Section: Resultsmentioning

confidence: 99%

“…described a significant correlation between the frequencies of NK cells and production of perforin and enhanced control of mycobacterial growth in both naïve in BCG-vaccinated individuals ( 48 ). In the aforementioned study of Cross et al., the rate of M.tb growth was increased in NK-depleted compared to un-depleted whole blood in the absence of rifampicin ( 107 ). Using the cattle direct PBMC MGIA, Pepponi et al.…”

Section: Resultsmentioning

confidence: 99%

Development and application of the direct mycobacterial growth inhibition assay: a systematic review

Painter,

Harriss,

Fletcher

et al. 2024

Front. Immunol.

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IntroductionFirst described by Wallis et al. in 2001 for the assessment of TB drugs, the direct mycobacterial growth inhibition assay (MGIA) offers a tractable ex vivo tool measuring the combined influences of host immunity, strain virulence and intervention effects. Over the past 13 years, we have led efforts to adapt the direct MGIA for the assessment of TB vaccines including optimisation, harmonisation and validation of BCG vaccine-induced responses as a benchmark, as well as assay transfer to institutes worldwide.MethodsWe have performed a systematic review on the primary published literature describing the development and applications of the direct MGIA from 2001 to June 2023 in accordance with the PRISMA reporting guidelines.ResultsWe describe 63 studies in which the direct MGIA has been applied across species for the evaluation of TB drugs and novel TB vaccine candidates, the study of clinical cohorts including those with comorbidities, and to further understanding of potential immune correlates of protection from TB. We provide a comprehensive update on progress of the assay since its conception and critically evaluate current findings and evidence supporting its utility, highlighting priorities for future directions.DiscussionWhile further standardisation and validation work is required, significant advancements have been made in the past two decades. The direct MGIA provides a potentially valuable tool for the early evaluation of TB drug and vaccine candidates, clinical cohorts, and immune mechanisms of mycobacterial control.Systematic review registrationhttps://www.crd.york.ac.uk/prospero/, identifier CRD42023423491.

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