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Clofazimine enhances the efficacy of BCG revaccination via stem cell-like memory T cells.

ABSTRACT: Tuberculosis (TB) is one of the deadliest diseases, claiming ~2 million deaths annually worldwide. The majority of people in TB endemic regions are vaccinated with Bacillus Calmette Guerin (BCG), which is the only usable vaccine available. BCG is efficacious against meningeal and disseminated TB in children, but protective responses are relatively short-lived and fail to protect against adult pulmonary TB. The longevity of vaccine efficacy critically depends on the magnitude of long-lasting central memory T (TCM) cells, a major source of which is stem cell-like memory T (TSM) cells. These TSM cells exhibit enhanced self-renewal capacity as well as to rapidly respond to antigen and generate protective poly-functional T cells producing IFN-?, TNF-?, IL-2 and IL-17. It is now evident that T helper Th 1 and Th17 cells are essential for host protection against TB. Recent reports have indicated that Th17 cells preserve the molecular signature for TSM cells, which eventually differentiate into IFN-?-producing effector cells. BCG is ineffective in inducing Th17 cell responses, which might explain its inadequate vaccine efficacy. Here, we show that revaccination with BCG along with clofazimine treatment promotes TSM differentiation, which continuously restores TCM and T effector memory (TEM) cells and drastically increases vaccine efficacy in BCG-primed animals. Analyses of these TSM cells revealed that they are predominantly precursors to host protective Th1 and Th17 cells. Taken together, these findings revealed that clofazimine treatment at the time of BCG revaccination provides superior host protection against TB by increasing long-lasting TSM cells.

SUBMITTER: Ahmad S

PROVIDER: S-EPMC7269335 | biostudies-literature | 2020 May

REPOSITORIES: biostudies-literature

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Clofazimine enhances the efficacy of BCG revaccination via stem cell-like memory T cells.

Ahmad Shaheer S Bhattacharya Debapriya D Gupta Neeta N Rawat Varsha V Tousif Sultan S Van Kaer Luc L Das Gobardhan G

PLoS pathogens 20200521 5

Tuberculosis (TB) is one of the deadliest diseases, claiming ~2 million deaths annually worldwide. The majority of people in TB endemic regions are vaccinated with Bacillus Calmette Guerin (BCG), which is the only usable vaccine available. BCG is efficacious against meningeal and disseminated TB in children, but protective responses are relatively short-lived and fail to protect against adult pulmonary TB. The longevity of vaccine efficacy critically depends on the magnitude of long-lasting cent ...[more]

PMID: 32437421

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Project description:BackgroundRecent Mycobacterium tuberculosis infection confers a predisposition to the development of tuberculosis disease, the leading killer among global infectious diseases. H4:IC31, a candidate subunit vaccine, has shown protection against tuberculosis disease in preclinical models, and observational studies have indicated that primary bacille Calmette-Guérin (BCG) vaccination may offer partial protection against infection.MethodsIn this phase 2 trial, we randomly assigned 990 adolescents in a high-risk setting who had undergone neonatal BCG vaccination to receive the H4:IC31 vaccine, BCG revaccination, or placebo. All the participants had negative results on testing for M. tuberculosis infection on the QuantiFERON-TB Gold In-tube assay (QFT) and for the human immunodeficiency virus. The primary outcomes were safety and acquisition of M. tuberculosis infection, as defined by initial conversion on QFT that was performed every 6 months during a 2-year period. Secondary outcomes were immunogenicity and sustained QFT conversion to a positive test without reversion to negative status at 3 months and 6 months after conversion. Estimates of vaccine efficacy are based on hazard ratios from Cox regression models and compare each vaccine with placebo.ResultsBoth the BCG and H4:IC31 vaccines were immunogenic. QFT conversion occurred in 44 of 308 participants (14.3%) in the H4:IC31 group and in 41 of 312 participants (13.1%) in the BCG group, as compared with 49 of 310 participants (15.8%) in the placebo group; the rate of sustained conversion was 8.1% in the H4:IC31 group and 6.7% in the BCG group, as compared with 11.6% in the placebo group. Neither the H4:IC31 vaccine nor the BCG vaccine prevented initial QFT conversion, with efficacy point estimates of 9.4% (P=0.63) and 20.1% (P=0.29), respectively. However, the BCG vaccine reduced the rate of sustained QFT conversion, with an efficacy of 45.4% (P=0.03); the efficacy of the H4:IC31 vaccine was 30.5% (P=0.16). There were no clinically significant between-group differences in the rates of serious adverse events, although mild-to-moderate injection-site reactions were more common with BCG revaccination.ConclusionsIn this trial, the rate of sustained QFT conversion, which may reflect sustained M. tuberculosis infection, was reduced by vaccination in a high-transmission setting. This finding may inform clinical development of new vaccine candidates. (Funded by Aeras and others; C-040-404 ClinicalTrials.gov number, NCT02075203 .).

Project description:INTRODUCTION:Tuberculosis (TB) is a disease caused by Mycobacterium tuberculosis (M.TB) and other species of the Mycobacterium tuberculosis complex. Globally, TB is ranked as the ninth leading cause of death and the leading cause of death from a single infectious agent. The bacille Calmette-Guerin (BCG) vaccine has been used globally since 1921 for the prevention of TB in humans, and was derived from an attenuated strain of Mycobacterium bovis. Evidence from previous randomised trials show that the efficacy of primary BCG vaccination against pulmonary TB ranged from no protection to very high protection. In addition, some studies suggest a benefit of BCG revaccination. For example, a recent trial conducted in South Africa showed that BCG revaccination of adolescents could reduce the risk of TB infection by half. However, we are not aware of any recent systematic reviews of the effects of BCG revaccination. Thus, the need for this systematic review of the effects of BCG revaccination on protection against TB infection and disease. METHOD AND ANALYSIS:We will search PubMed, the Cochrane Central Register of Controlled Trials, EMBASE, WHO International Clinical Trials Registry Platform and reference lists of relevant publications for potentially eligible studies. We will screen search outputs, select eligible studies, extract data and assess risk of bias in duplicate. Discrepancies will be resolved by discussion and consensus or arbitration. We will use the Grading of Recommendations Assessment, Development and Evaluation method to assess the certainty of the evidence. The planned systematic review was registered with the International Prospective Register of Systematic Reviews (PROSPERO) in August 2018. ETHICS AND DISSEMINATION:Publicly available data will be used, hence no formal ethical approval will be required for this review. The findings of the review will be disseminated through conference presentations and publication in an open-access peer-reviewed journal. PROSPERO REGISTRATION NUMBER:CRD42018105916.

Dataset Information

Clofazimine enhances the efficacy of BCG revaccination via stem cell-like memory T cells.

Publications

Clofazimine enhances the efficacy of BCG revaccination via stem cell-like memory T cells.

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