Macropinocytosis as a potential mechanism driving neurotropism of .

can invade the central nervous system by crossing the blood-brain barrier via a transcellular mechanism that relies on multiple host factors. In this narrative, we review the evidence that a direct interplay between and brain endothelial cells forms the basis for invasion and transmigration across the brain endothelium. Adherence and internalization of is dependent on transmembrane proteins, including a hyaluronic acid receptor and an ephrin receptor tyrosine kinase.

Antifungal activity of 6-substituted amiloride and hexamethylene amiloride (HMA) analogs.

Fungal infections have become an increasing threat as a result of growing numbers of susceptible hosts and diminishing effectiveness of antifungal drugs due to multi-drug resistance. This reality underscores the need to develop novel drugs with unique mechanisms of action. We recently identified 5-(,-hexamethylene)amiloride (HMA), an inhibitor of human Na/H exchanger isoform 1, as a promising scaffold for antifungal drug development.

Discovery and Characterization of a Potent Antifungal Peptide through One-Bead, One-Compound Combinatorial Library Screening.

This work describes the discovery of a bead-bound membrane-active peptide (MAP), LBF127, that selectively binds fungal giant unilamellar vesicles (GUVs) over mammalian GUVs. LBF127 was re-synthesized in solution form and demonstrated to have antifungal activity with limited hemolytic activity and cytotoxicity against mammalian cells. Through systematic structure-activity relationship studies, including N- and C-terminal truncation, alanine-walk, and d-amino acid substitution, an optimized peptide, K-oLBF127, with higher potency, less hemolytic activity, and cytotoxicity emerged.

Characterization of the Growth and Morphology of a BSL-2 Strain That Persists in the Parasitic Life Cycle at Ambient CO.

is a dimorphic fungus responsible for Valley Fever and is the cause of severe morbidity and mortality in the infected population. Although there is some insight into the genes, pathways, and growth media involved in the parasitic to saprophytic growth transition, the exact determinants that govern this switch are largely unknown. In this work, we examined the growth and morphology of a strain ( S/E) that efficiently produces spherules and endospores and persists in the parasitic life cycle at ambient CO.

The Antifungal Activity of HMA, an Amiloride Analog and Inhibitor of Na/H Exchangers.

One path toward identifying effective and easily accessible antifungals is to repurpose commonly used drugs. Amiloride, a widely used diuretic, inhibits different isoforms of Na/H exchangers, Na channels, and Na/Ca exchangers. Here, we found that amiloride had poor antifungal activity against isolates of prompting the examination of the amiloride analog, HMA [5-(,-hexamethylene)amiloride].

An Antivirulence Approach for Preventing Cryptococcus neoformans from Crossing the Blood-Brain Barrier via Novel Natural Product Inhibitors of a Fungal Metalloprotease.

() is the leading cause of fungal meningitis, a deadly disease with limited therapeutic options. Dissemination to the central nervous system hinges on the ability of to breach the blood-brain barrier (BBB) and is considered an attribute of virulence. Targeting virulence instead of growth for antifungal drug development has not been fully exploited despite the benefits of this approach.

Cryptococcal Meningitis and Anti-virulence Therapeutic Strategies.

Fungal infections of the central nervous system are responsible for significant morbidity and mortality. () is the primary cause of fungal meningitis. Infection begins in the lung after inhalation of fungal spores but often spreads to other organs, particularly the brain in immunosuppressed individuals.

The structure-function analysis of the Mpr1 metalloprotease determinants of activity during migration of fungal cells across the blood-brain barrier.

Cryptococcal meningoencephalitis, the most common form of cryptococcosis, is caused by the opportunistic fungal pathogen, Cryptococcus neoformans. Molecular strategies used by C. neoformans to invade the central nervous system (CNS) have been the focus of several studies.

Flucytosine resistance in Cryptococcus gattii is indirectly mediated by the FCY2-FCY1-FUR1 pathway.

Cryptococcosis is an opportunistic fungal infection caused by members of the two sibling species complexes: Cryptococcus neoformans and Cryptococcus gattii. Flucytosine (5FC) is one of the most widely used antifungals against Cryptococcus spp., yet very few studies have looked at the molecular mechanisms responsible for 5FC resistance in this pathogen.

Fluconazole Susceptibility in Cryptococcus gattii Is Dependent on the ABC Transporter Pdr11.

Cryptococcus gattii isolates from the Pacific Northwest have exhibited higher fluconazole MICs than isolates from other sites. The mechanism of fluconazole resistance in C. gattii is unknown.

The Cch1-Mid1 High-Affinity Calcium Channel Contributes to the Virulence of Cryptococcus neoformans by Mitigating Oxidative Stress.

Pathogenic fungi have developed mechanisms to cope with stresses imposed by hosts. For Cryptococcus spp., this implies active defense mechanisms that attenuate and ultimately overcome the onslaught of oxidative stresses in macrophages.

Invasion of the central nervous system by Cryptococcus neoformans requires a secreted fungal metalloprotease.

Unlabelled: Cryptococcus spp. cause life-threatening fungal infection of the central nervous system (CNS), predominantly in patients with a compromised immune system. Why Cryptococcus neoformans has this remarkable tropism for the CNS is not clear.

Cryptococcus neoformans promotes its transmigration into the central nervous system by inducing molecular and cellular changes in brain endothelial cells.

Cryptococcus spp. cause fungal meningitis, a life-threatening infection that occurs predominately in immunocompromised individuals. In order for Cryptococcus neoformans to invade the central nervous system (CNS), it must first penetrate the brain endothelium, also known as the blood-brain barrier (BBB).

Activity of the calcium channel pore Cch1 is dependent on a modulatory region of the subunit Mid1 in Cryptococcus neoformans.

Calcium (Ca(2+))-mediated signaling events in fungal pathogens such as Cryptococcus neoformans are central to physiological processes, including those that mediate stress responses and promote virulence. The Cch1-Mid1 channel (CMC) represents the only high-affinity Ca(2+) channel in the plasma membrane of fungal cells; consequently, cryptococci cannot survive in low-Ca(2+) environments in the absence of CMC. Previous electrophysiological characterization revealed that Cch1, the predicted channel pore, and Mid1, a binding partner of Cch1, function as a store-operated Ca(2+)-selective channel gated by depletion of endoplasmic reticulum (ER) Ca(2+) stores.

Cch1 restores intracellular Ca2+ in fungal cells during endoplasmic reticulum stress.

Pathogens endure and proliferate during infection by exquisitely coping with the many stresses imposed by the host to prevent pathogen survival. Recent evidence has shown that fungal pathogens and yeast respond to insults to the endoplasmic reticulum (ER) by initiating Ca(2+) influx across their plasma membrane. Although the high affinity Ca(2+) channel, Cch1, and its subunit Mid1, have been suggested as the protein complex responsible for mediating Ca(2+) influx, a direct demonstration of the gating mechanism of the Cch1 channel remains elusive.

Immortalized human brain endothelial cell line HCMEC/D3 as a model of the blood-brain barrier facilitates in vitro studies of central nervous system infection by Cryptococcus neoformans.

Cryptococcus neoformans cells must cross the blood-brain barrier prior to invading the central nervous system. Here we demonstrate that the immortalized human brain endothelial cell line HCMEC/D3 is a useful alternative to primary brain endothelial cells as a model of the blood-brain barrier for studies of central nervous system infection.

The functional expression of toxic genes: lessons learned from molecular cloning of CCH1, a high-affinity Ca2+ channel.

Some genes cannot be cloned by conventional methods because in most cases the genes or gene products are toxic to Escherichia coli. CCH1 is a high-affinity Ca(2+) channel present in the plasma membrane of Cryptococcus neoformans and other fungi. Like many toxic genes, the molecular cloning of CCH1 has been a major challenge; consequently, direct studies of CCH1 channel activity in heterologous expression systems have been impossible.

Astemizole and an analogue promote fungicidal activity of fluconazole against Cryptococcus neoformans var. grubii and Cryptococcus gattii.

Cryptococcus neoformans is the leading cause of fungal meningitis, a life-threatening infection that occurs predominately in immuocompromised patients. Current drug therapies are limited to amphotericin B, flucytosine and the azoles since the echinocandins have no demonstrated activity against yeast like pathogens. Fluconazole, a drug belonging to the azole class and often the only available antifungal in the developing world, is fungistatic and therefore not effective in clearing cryptococcal infections in immunosuppressed individuals.