title: Cryptococcus neoformans Intracellular Proliferation and Capsule Size Determines Early Macrophage Control of Infection.
abstract: Cryptococcus neoformans is a significant fungal pathogen of immunocompromised patients. Many questions remain regarding the function of macrophages in normal clearance of cryptococcal infection and the defects present in uncontrolled cryptococcosis. Two current limitations are: 1) The difficulties in interpreting studies using isolated macrophages in the context of the progression of infection, and 2) The use of high resolution imaging in understanding immune cell behavior during animal infection. Here we describe a high-content imaging method in a zebrafish model of cryptococcosis that permits the detailed analysis of macrophage interactions with C. neoformans during infection. Using this approach we demonstrate that, while macrophages are critical for control of C. neoformans, a failure of macrophage response is not the limiting defect in fatal infections. We find phagocytosis is restrained very early in infection and that increases in cryptococcal number are driven by intracellular proliferation. We show that macrophages preferentially phagocytose cryptococci with smaller polysaccharide capsules and that capsule size is greatly increased over twenty-four hours of infection, a change that is sufficient to severely limit further phagocytosis. Thus, high-content imaging of cryptococcal infection in vivo demonstrates how very early interactions between macrophages and cryptococci are critical in the outcome of cryptococcosis.
authors.affiliation: Department of Infection, Immunity and Cardiovascular Disease, Medical School, University of Sheffield, Sheffield, UK.|Bateson Centre, University of Sheffield, Sheffield, UK.
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Bojarczuk
authors.affiliation: Department of Infection, Immunity and Cardiovascular Disease, Medical School, University of Sheffield, Sheffield, UK.|Bateson Centre, University of Sheffield, Sheffield, UK.
authors.forename: Katie A
authors.initials: KA
authors.lastname: Miller
authors.affiliation: Department of Infection, Immunity and Cardiovascular Disease, Medical School, University of Sheffield, Sheffield, UK.|Bateson Centre, University of Sheffield, Sheffield, UK.
authors.forename: Richard
authors.initials: R
authors.lastname: Hotham
authors.affiliation: Department of Infection, Immunity and Cardiovascular Disease, Medical School, University of Sheffield, Sheffield, UK.|Bateson Centre, University of Sheffield, Sheffield, UK.
authors.forename: Amy
authors.initials: A
authors.lastname: Lewis
authors.affiliation: Department of Infection, Immunity and Cardiovascular Disease, Medical School, University of Sheffield, Sheffield, UK.|Bateson Centre, University of Sheffield, Sheffield, UK.
authors.forename: Nikolay V
authors.initials: NV
authors.lastname: Ogryzko
authors.affiliation: Department of Infection, Immunity and Cardiovascular Disease, Medical School, University of Sheffield, Sheffield, UK.|Bateson Centre, University of Sheffield, Sheffield, UK.
authors.forename: Alfred A
authors.initials: AA
authors.lastname: Kamuyango
authors.affiliation: Institute of Microbiology and Infection and School of Biosciences, University of Birmingham, Birmingham, UK.
authors.forename: Helen
authors.initials: H
authors.lastname: Frost
authors.affiliation: Department of Infection, Immunity and Cardiovascular Disease, Medical School, University of Sheffield, Sheffield, UK.|Bateson Centre, University of Sheffield, Sheffield, UK.
authors.forename: Rory H
authors.initials: RH
authors.lastname: Gibson
authors.affiliation: School of Mathematics and Statistics, University of Sheffield, Sheffield, UK.
authors.forename: Eleanor
authors.initials: E
authors.lastname: Stillman
authors.affiliation: Institute of Microbiology and Infection and School of Biosciences, University of Birmingham, Birmingham, UK.|NIHR Surgical Reconstruction and Microbiology Research Centre, University Hospitals of Birmingham NHS Foundation Trust, Queen Elizabeth Hospital, Birmingham, UK.
authors.forename: Robin C
authors.initials: RC
authors.lastname: May
authors.affiliation: Department of Infection, Immunity and Cardiovascular Disease, Medical School, University of Sheffield, Sheffield, UK.|Bateson Centre, University of Sheffield, Sheffield, UK.
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Renshaw
authors.affiliation: Department of Infection, Immunity and Cardiovascular Disease, Medical School, University of Sheffield, Sheffield, UK.|Bateson Centre, University of Sheffield, Sheffield, UK.
authors.forename: Simon A
authors.initials: SA
authors.lastname: Johnston
mesh_terms: D000818:Animals; D049109:Cell Proliferation; D003453:Cryptococcosis / Q000378:metabolism* / Q000473:pathology; D003455:Cryptococcus neoformans / Q000378:metabolism*; D005393:Fish Diseases / Q000378:metabolism* / Q000382:microbiology; D008264:Macrophages / Q000378:metabolism* / Q000382:microbiology; D030781:Organisms, Genetically Modified / Q000378:metabolism; D015027:Zebrafish / Q000378:metabolism* / Q000382:microbiology