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Background Alzheimer’s disease (AD) is the most prevalent form of age-related dementia, and its effect on society increases exponentially as the population ages. Accumulating evidence suggests that neuroinflammation, mediated by the brain’s innate immune system, contributes to AD neuropathology and exacerbates the course of the disease. However, there is no experimental evidence for a causal link between systemic inflammation or neuroinflammation and the onset of the disease. Methods The viral mimic, polyriboinosinic-polyribocytidilic acid (PolyI:C) was used to stimulate the immune system of experimental animals. Wild-type (WT) and transgenic mice were exposed to this cytokine inducer prenatally (gestation day (GD)17) and/or in adulthood. Behavioral, immunological, immunohistochemical, and biochemical analyses of AD-associated neuropathologic changes were performed during aging. Results We found that a systemic immune challenge during late gestation predisposes WT mice to develop AD-like neuropathology during the course of aging. They display chronic elevation of inflammatory cytokines, an increase in the levels of hippocampal amyloid precursor protein (APP) and its proteolytic fragments, altered Tau phosphorylation, and mis-sorting to somatodendritic compartments, and significant impairments in working memory in old age. If this prenatal infection is followed by a second immune challenge in adulthood, the phenotype is strongly exacerbated, and mimics AD-like neuropathologic changes. These include deposition of APP and its proteolytic fragments, along with Tau aggregation, microglia activation and reactive gliosis. Whereas Aβ peptides were not significantly enriched in extracellular deposits of double immune-challenged WT mice at 15 months, they dramatically increased in age-matched immune-challenged transgenic AD mice, precisely around the inflammation-induced accumulations of APP and its proteolytic fragments, in striking similarity to the post-mortem findings in human patients with AD. Conclusion Chronic inflammatory conditions induce age-associated development of an AD-like phenotype in WT mice, including the induction of APP accumulations, which represent a seed for deposition of aggregation-prone peptides. The PolyI:C mouse model therefore provides a unique tool to investigate the molecular mechanisms underlying the earliest pathophysiological changes preceding fibrillary Aβ plaque deposition and neurofibrillary tangle formations in a physiological context of aging. Based on the similarity between the changes in immune-challenged mice and the development of AD in humans, we suggest that systemic infections represent a major risk factor for the development of AD.

Acremonium spp. cause human superficial infections including mycetoma, onychomycosis and keratitis. There are a few reports of systemic involvement in immunocompromised patients. However, isolated pulmonary infection in otherwise healthy hosts has never been reported in the literature. Herein, we report a 59 year-old diabetic man with non-resolving pneumonia due to Acremonium spp. and provide a consensus review of the published clinical cases of systemic and respiratory tract infections.

The morphogenetic program in the pathogenic fungus Candida albicans, including the dimorphic transition, is an interesting field of study, not only because it is absent in the commonly used model yeast Saccharomyces cerevisiae, but because of the close relationship between hyphal development and virulence of C. albicans. We studied one of the most important aspects of fungal morphogenesis-the septin ring-in C. albicans. By using a fusion construct to green fluorescent protein (GFP), the subcellular localization and dynamics of C. albicans Cdc10 in the different morphologies that this fungus is able to adopt was identified. The localization features reached were contrasted and compared with the results obtained from Candida cells directly extracted from an animal infection model under environmental conditions as similar as possible to the physiological conditions encountered by C. albicans during host infection.