Research


Research in the Wozniak lab focuses on innate immune cell interactions with the fungal pathogen Cryptococcus neoformans.

Current Research: We work on three main projects in the lab: 1) examining the mechanism involved in fungal cell wall degradation by the lysosomal enzyme cathepsin B, 2) examining dendritic cell (DC) factors associated with killing the fungal pathogen Cryptococcus neoformans and 3) determining mechanisms that govern macrophage killing vs intracellular growth of fungal pathogens.Cryptococcus neoformans is an opportunistic fungal pathogen that primarily affects immune compromised patients, including those with AIDS and those on immune suppressive therapies to prevent organ transplant rejection. The disease begins as a pulmonary infection that eventually spreads to the central nervous system causing meningitis. Current estimates suggest that approximately 275,000 people are infected with this pathogen each year, and approximately 180,000 die each year due to cryptococcal meningitis (Rajasingham et al, The Lancet, 2017). The initial interaction with the host begins in the lung, and the innate immune cells of the lung (primarily macrophages and dendritic cells) are the front-line of defense against this pathogen.

Mechanism by which the lysosomal enzyme cathepsin B degrades the cryptococcal cell wall: Cat B EMs webThis project will examine mechanisms involved with cathepsin B degradation of the cryptococcal cell wall. We have shown that the lysosomal enzyme, cathepsin B, is capable of killing C. neoformans. This happens because of the formation of a hole in the cell wall and leads to osmotic lysis of the organism (Hole et. al, Scientific Reports, 2012). However, we do not understand the mechanism of activity of cathepsin B on the fungal cell wall components.

DC lysosome factors associated with killing C. neoformans: This project will identifiy components present in the lysosome of dendritic cells (DCs) that are responsible for killing of the organism. We have already shown that one lysosomal component, cathepsin B, is important in killing C. neoformans. Many other anti-fungal components exist in the lysosome, and we have fractionated the lysosomal extract and have shown that several fractions have anti-cryptococcal activity. We are currently performing mass spectrometry to identify these components. Following identification, these components will be used to determine both the components responsible for anti-fungal activity as well as the mechanisms by which these can kill the fungus.

Mechanisms governing fungal intracellular growth vs intracellular killing in Human macs with captions webmacrophages: This project examines the macrophage side of the interaction of fungal pathogens, including C. neoformans, with different subsets of macrophages. Many laboratories have examined intracellular growth of C. neoformans and other fungal pathogens inside of macrophages, primarily focusing on cell lines. In primary cells from mice and humans, macrophages subsets exist that interact differently with pathogens.We have shown that the interaction of C. neofomans with two different subsets of human macrophages results in two different outcomes – intracellular growth or intracellular killing. We are currently planning to perform RNA-seq in order to determine differential gene expression in each type of macrophage upon interaction with C. neoformans. These studies can also be applied to other fungal pathogens. The ultimate goal of these studies is to identify mechanisms used by anti-fungal macrophages that could be applied as immunotherapy against fatal C. neoformans infections.

Human macs image flow with captions web