Chapter

The New Paradigm of Immunity to Tuberculosis

Volume 783 of the series Advances in Experimental Medicine and Biology pp 251-266

Date:

Looking Within the Zebrafish to Understand the Tuberculous Granuloma

  • Lalita RamakrishnanAffiliated withDepartment of Microbiology, Medicine and Immunology, University of Washington Email author 

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Abstract

Tuberculosis is characterized by the formation of complex immune cell aggregates called granulomas, which for nearly a century have been viewed as critical host-beneficial structures to restrict bacterial growth and spread. A different view has now emerged from real-time visualization of granuloma formation and its consequences in the optically transparent and genetically tractable zebrafish larva. Pathogenic mycobacteria have developed mechanisms to use host granulomas for their expansion and dissemination, at least during the innate phases of infection. Host processes that are intended to be beneficial—death of infected macrophages and their subsequent phagocytosis by macrophages that are newly recruited to the growing granuloma—are harnessed by mycobacteria for their own benefit. Mycobacteria can also render the granuloma a safe-haven in the more advanced stages of infection. An understanding of the host and bacterial pathways involved in tuberculous granuloma formation may suggest new ways to combat mycobacterial infection.

Keywords

Tubercles Tuburculous granuloma Mycobacterium tuberculosis Macrophages Necrosis Mycobacterium marinum Zebrafish Tumor necrosis factor Mycobacterium bovis bacillus Calmette-Guérin (BCG) vaccine strain Neutrophils Cell death Host matrix metalloproteinase 9 (MMP9) Apoptosis Mycobacteria