WhiB4 is required for the reactivation of latent infection of Mycobacterium marinum in zebrafish [ChIP-Seq]
Ontology highlight
ABSTRACT: Granulomas are the pathological hallmark of tuberculosis (TB). In individuals latently infected with Mycobacterium tuberculosis (M. tb), the bacteria are thought to reside within the granulomas in a nonreplicating dormant state due to the lack of oxygen and nutrients. However, a portion of these individuals will develop active TB and little is known on the bacterial mechanisms/factors involved in this process. In this study, we found that WhiB4, an oxygen sensor and a transcription factor, plays a critical role in disease progression and reactivation of Mycobacterium marinum (M. marinum) infection in zebrafish. We show that the whiB4 mutant of M. marinum caused latent infection in adult zebrafish, which is characterized by the stable bacterial loads, constant number of non-necrotized granulomas in fewer organs, and reduced immune responses compared to zebrafish infected with the wild type bacteria or the complemented strain. The mutant bacteria in zebrafish were also less responsive to antibiotic treatments. Moreover, the whiB4 mutant was defective in resuscitation from hypoxia-induced dormancy and that the DosR regulon was dysregulated in the mutant. Taken together, our results suggest that WhiB4 is a major driver of reactivation from latent infection and that WhiB4 is an attractive target for the development of novel therapeutics, which may help to prevent the reactivation of latent infection thereby reducing the incidences of active TB.
Project description:Granulomas are the pathological hallmark of tuberculosis (TB). In individuals latently infected with Mycobacterium tuberculosis (M. tb), the bacteria are thought to reside within the granulomas in a nonreplicating dormant state due to the lack of oxygen and nutrients. However, a portion of these individuals will develop active TB and little is known on the bacterial mechanisms/factors involved in this process. In this study, we found that WhiB4, an oxygen sensor and a transcription factor, plays a critical role in disease progression and reactivation of Mycobacterium marinum (M. marinum) infection in zebrafish. We show that the whiB4 mutant of M. marinum caused latent infection in adult zebrafish, which is characterized by the stable bacterial loads, constant number of non-necrotized granulomas in fewer organs, and reduced immune responses compared to zebrafish infected with the wild type bacteria or the complemented strain. The mutant bacteria in zebrafish were also less responsive to antibiotic treatments. Moreover, the whiB4 mutant was defective in resuscitation from hypoxia-induced dormancy and that the DosR regulon was dysregulated in the mutant. Taken together, our results suggest that WhiB4 is a major driver of reactivation from latent infection and that WhiB4 is an attractive target for the development of novel therapeutics, which may help to prevent the reactivation of latent infection thereby reducing the incidences of active TB.
Project description:Granulomas are the pathological hallmark of tuberculosis (TB). In individuals latently infected with Mycobacterium tuberculosis (M. tb), the bacteria are thought to reside within the granulomas in a nonreplicating dormant state due to the lack of oxygen and nutrients. However, a portion of these individuals will develop active TB and little is known on the bacterial mechanisms/factors involved in this process. In this study, we found that WhiB4, an oxygen sensor and a transcription factor, plays a critical role in disease progression and reactivation of Mycobacterium marinum (M. marinum) infection in zebrafish. We show that the whiB4 mutant of M. marinum caused latent infection in adult zebrafish, which is characterized by the stable bacterial loads, constant number of non-necrotized granulomas in fewer organs, and reduced immune responses compared to zebrafish infected with the wild type bacteria or the complemented strain. The mutant bacteria in zebrafish were also less responsive to antibiotic treatments. Moreover, the whiB4 mutant was defective in resuscitation from hypoxia-induced dormancy and that the DosR regulon was dysregulated in the mutant. Taken together, our results suggest that WhiB4 is a major driver of reactivation from latent infection and that WhiB4 is an attractive target for the development of novel therapeutics, which may help to prevent the reactivation of latent infection thereby reducing the incidences of active TB.
Project description:Granulomas are the pathological hallmark of tuberculosis (TB). In individuals latently infected with Mycobacterium tuberculosis (M. tb), the bacteria are thought to reside within the granulomas in a nonreplicating dormant state due to the lack of oxygen and nutrients. However, a portion of these individuals will develop active TB and little is known on the bacterial mechanisms/factors involved in this process. In this study, we found that WhiB4, an oxygen sensor and a transcription factor, plays a critical role in disease progression and reactivation of Mycobacterium marinum (M. marinum) infection in zebrafish. We show that the whiB4 mutant of M. marinum caused latent infection in adult zebrafish, which is characterized by the stable bacterial loads, constant number of non-necrotized granulomas in fewer organs, and reduced immune responses compared to zebrafish infected with the wild type bacteria or the complemented strain. The mutant bacteria in zebrafish were also less responsive to antibiotic treatments. Moreover, the whiB4 mutant was defective in resuscitation from hypoxia-induced dormancy and that the DosR regulon was dysregulated in the mutant. Taken together, our results suggest that WhiB4 is a major driver of reactivation from latent infection and that WhiB4 is an attractive target for the development of novel therapeutics, which may help to prevent the reactivation of latent infection thereby reducing the incidences of active TB.
Project description:Proteins expressed and exported out of the mycobacterial biofilm cells into granulomatous environment during infection were identified by LC-MS/MS. To this end, adult 5- to 10-month-old female AB wild-type zebrafish (Danio rerio) were infected with 4-day old M. marinum ATCC927 (carrying the pTEC27 plasmid expressing the tdTomato fluorescent protein) cells. After 8 weeks post infection, ten zebrafish were euthanized, and red fluorescent mycobacterial granulomas were carefully dissected from the zebrafish ovaries. Ten granulomas were collected per tube, frozen on dry ice and stored at -80 °C until preparation for proteomics. Altogether, ten replicate samples, each with ten mycobacterial granulomas, were subjected to protein extraction and LC-MS/MS identification.
Project description:Zebrafish / Mycobacterium marinum model is useful in modeling human tuberculosis, as zebrafish recapitulate several aspects of the disease. We generated a mutant line for the inflammasome adaptor gene pycard to study the loss of inflammasome signaling in adult zebrafish M. marinum infection. We discovered a number of immunity related genes up- or downregulated in mutant pycard zebrafish in comparison to WT control siblings. The RNA-seq was conducted using a low dose infection (approximately 30 CFU) at 4 weeks post infection, from the kidney of adult male fish. Mock injected controls received PBS instead of bacteria.