Tuberculosis (TB), which in humans is caused by Mycobacterium tuberculosis, is one of the leading causes of death from infectious diseases worldwide. There are more TB cases now than at any other time in history and this is largely attributed to the HIV epidemic. Factors that make it difficult to thwart the TB epidemic include the lack of an effective vaccine and the requirement for long multidrug treatment regimens to obtain cures. The latter has led to the selection and spread of extensively drug resistance strains that make TB the lethal disease it was in the pre-antibiotic era. TB results from complex interactions between mycobacteria and their vertebrate hosts. Upon infection by pathogenic mycobacteria, macrophages are recruited to the infection site where they phagocytose the bacteria. However, instead of eradicating the bacteria, macrophages migrate into deeper tissues serving to disseminate the infection. Additional uninfected macrophages are then recruited, and aggregate into the hallmark pathological structure of TB, the granuloma. Long thought to be a host beneficial structure that walls off the infection, we have found that the granuloma, at least in its early stages, serves as a vehicle for bacterial expansion and dissemination. To understand the process of granuloma development, we study Mycobacterium marinum, a close genetic relative of M. tuberculosis, in its natural host, the zebrafish. Zebrafish are genetically tractabl vertebrates with a similar complex immune system to that of mammals and are transparent in the early weeks of development. These features allow a detailed, serial, live-monitoring of infection in animals that have been genetically manipulated. The long term objective of this proposal is to better understand the host-pathogen interactions that occur during granuloma development, with the goal of identifying targets for potential host-directed therapeutics. In this proposal specifically, we will use a variety of molecular and genetic techniques to probe pathways of cell death and recruitment during granuloma development, and to identify pharmacological agents that intercept this process to the benefit of the host.
Tuberculosis is a leading cause of death with more cases now than at any previous time. TB has been difficult to eradicate due to a requirement for long treatment regimens, which lead to non-compliance, and the development of antibiotic resistance. This proposal will identify strategies and molecules that are exploited by the bacteria to produce disease, so as to direct new classes of host-targeting drugs to treat TB. It will also identify host markers of susceptibility that will aid in the development of more efficacious, personalized treatment regimens.
|Hernandez, Rafael E; Galitan, Louie; Cameron, James et al. (2018) Delay of Initial Feeding of Zebrafish Larvae Until 8 Days Postfertilization Has No Impact on Survival or Growth Through the Juvenile Stage. Zebrafish 15:515-518|
|Takaki, Kevin; Ramakrishnan, Lalita; Basu, Soumyava (2018) A zebrafish model for ocular tuberculosis. PLoS One 13:e0194982|
|Pagán, Antonio J; Ramakrishnan, Lalita (2018) The Formation and Function of Granulomas. Annu Rev Immunol 36:639-665|
|Madigan, Cressida A; Cambier, C J; Kelly-Scumpia, Kindra M et al. (2017) A Macrophage Response to Mycobacterium leprae Phenolic Glycolipid Initiates Nerve Damage in Leprosy. Cell 170:973-985.e10|
|Roh-Johnson, Minna; Shah, Arish N; Stonick, Jason A et al. (2017) Macrophage-Dependent Cytoplasmic Transfer during Melanoma Invasion In Vivo. Dev Cell 43:549-562.e6|
|Pagán, Antonio J; Ramakrishnan, Lalita (2017) TORmented macrophages spontaneously form granulomas. Nat Immunol 18:252-253|
|Madigan, Cressida A; Cameron, James; Ramakrishnan, Lalita (2017) A Zebrafish Model of Mycobacterium leprae Granulomatous Infection. J Infect Dis 216:776-779|
|Cambier, C J; O'Leary, Seónadh M; O'Sullivan, Mary P et al. (2017) Phenolic Glycolipid Facilitates Mycobacterial Escape from Microbicidal Tissue-Resident Macrophages. Immunity 47:552-565.e4|
|Conrad, William H; Osman, Morwan M; Shanahan, Jonathan K et al. (2017) Mycobacterial ESX-1 secretion system mediates host cell lysis through bacterium contact-dependent gross membrane disruptions. Proc Natl Acad Sci U S A 114:1371-1376|
|Levitte, Steven; Adams, Kristin N; Berg, Russell D et al. (2016) Mycobacterial Acid Tolerance Enables Phagolysosomal Survival and Establishment of Tuberculous Infection In Vivo. Cell Host Microbe 20:250-8|
Showing the most recent 10 out of 29 publications