Impact of Micafungin on Candida auris ß-glucan Masking and Neutrophil Interactions.

Invasive fungal pathogen Candida auris has become a public health threat causing outbreaks of high mortality infections. Drug resistance often limits treatment options. For Candida albicans, subinhibitory concentrations of echinocandins unmask immunostimulatory ß-glucan, augmenting immunity. Here we analyze the impact of echinocandin treatment of C. auris on ß-glucan exposure and human neutrophil interactions. We show subinhibitory concentrations lead to minimal glucan unmasking and only subtle influences on neutrophil functions for the isolates belonging to circulating clades. The data suggest that echinocandin treatment will not largely alter phagocytic responses. Glucan masking pathways appear to differ between C. auris and C. albicans.

Liposomal formulation of a new antifungal hybrid compound provides protection against Candida auris in the ex vivo skin colonization model.

The newly emerged pathogen, Candida auris, presents a serious threat to public health worldwide. This multidrug-resistant yeast often colonizes and persists on the skin of patients, can easily spread from person to person, and can cause life-threatening systemic infections. New antifungal therapies are therefore urgently needed to limit and control both superficial and systemic C. auris infections. In this study, we designed a novel antifungal agent, PQA-Az-13, that contains a combination of indazole, pyrrolidine, and arylpiperazine scaffolds substituted with a trifluoromethyl moiety. PQA-Az-13 demonstrated antifungal activity against biofilms of a set of 10 different C. auris clinical isolates, representing all four geographical clades distinguished within this species. This compound showed strong activity, with MIC values between 0.67 and 1.25 µg/mL. Cellular proteomics indicated that PQA-Az-13 partially or completely inhibited numerous enzymatic proteins in C. auris biofilms, particularly those involved in both amino acid biosynthesis and metabolism processes, as well as in general energy-producing processes. Due to its hydrophobic nature and limited aqueous solubility, PQA-Az-13 was encapsulated in cationic liposomes composed of soybean phosphatidylcholine (SPC), 1,2-dioleoyloxy-3-trimethylammonium-propane chloride (DOTAP), and N-(carbonyl-methoxypolyethylene glycol-2000)-1,2-distearoyl-sn-glycero-3-phosphoethanolamine, sodium salt (DSPE-PEG 2000), and characterized by biophysical and spectral techniques. These PQA-Az-13-loaded liposomes displayed a mean size of 76.4 nm, a positive charge of +45.0 mV, a high encapsulation efficiency of 97.2%, excellent stability, and no toxicity to normal human dermal fibroblasts. PQA-Az-13 liposomes demonstrated enhanced antifungal activity levels against both C. auris in in vitro biofilms and ex vivo skin colonization models. These initial results suggest that molecules like PQA-Az-13 warrant further study and development.

Phencyclidine-Like Abuse Liability and Psychosis-Like Neurocognitive Effects of Novel Arylcyclohexylamine Drugs of Abuse in Rodents.

Abuse of novel arylcyclohexylamines (ACX) poses risks for toxicities, including adverse neurocognitive effects. In vivo effects of ring-substituted analogs of phencyclidine (PCP), eticyclidine (PCE), and ketamine are understudied. Adult male National Institutes of Health Swiss mice were used to assess locomotor effects of PCP and its 3-OH, 3-MeO, 3-Cl, and 4-MeO analogs, PCE and its 3-OH and 3-MeO analogs, and ketamine and its deschloro and 2F-deschloro analogs, in comparison with those of methamphetamine (METH), 3,4-methylenedioxymethamphetamine (MDMA), and two benzofuran analogs of MDMA. PCP-like interoceptive effects for all of these ACXs were determined using a food-reinforced drug discrimination procedure in adult male Sprague Dawley rats. A novel operant assay of rule-governed behavior incorporating aspects of attentional set-shifting was used to profile psychosis-like neurocognitive effects of PCP and 3-Cl-PCP in rats, in comparison with cocaine and morphine. PCP-like ACXs were more effective locomotor stimulants than the amphetamines, PCE-like ACXs were as effective as the amphetamines, and ketamine-like ACXs were less effective than the amphetamines. Addition of -Cl, -OH, or -OMe at the 3-position on the aromatic ring did not impact locomotor effectiveness, but addition of -OMe at the 4-position reduced locomotor effectiveness. Lethal effects were induced by drugs with -OH at the 3-position or -OMe at the 3- or 4-position. All novel ACXs substituted at least partially for PCP, and PCP and 3-Cl-PCP elicited dose-dependent psychosis-like neurocognitive deficits in the rule-governed behavior task not observed with cocaine or morphine. Novel ACXs exhibit substantial abuse liability and toxicities not necessarily observed with their parent drugs. SIGNIFICANCE STATEMENT: Novel arylcyclohexylamine analogs of PCP, PCE, and ketamine are appearing on the illicit market, and abuse of these drugs poses risks for toxicities, including adverse neurocognitive effects. These studies demonstrate that the novel ACXs exhibit PCP-like abuse liability in the drug discrimination assay, elicit varied locomotor stimulant and lethal effects in mice, and induce psychosis-like neurocognitive effects in rats.

Ex Vivo Human and Porcine Skin Effectively Model Candida auris Colonization, Differentiating Robust and Poor Fungal Colonizers.

Candida auris proliferates and persists on the skin of patients, often leading to health care-associated infections with high mortality. Here, we describe 2 clinically relevant skin models and show that C. auris grows similarly on human and porcine skin. Additionally, we demonstrate that other Candida spp., including those with phylogenetic similarity to C. auris, do not display high growth in the skin microenvironment. These studies highlight the utility of 2 ex vivo models of C. auris colonization that allow reproducible differentiation among Candida spp., which should be a useful tool for comparison of C. auris clinical isolates and genetically mutated strains.

Development of a Novel In Vitro Primary Human Monocyte-Derived Macrophage Model To Study Reactivation of HIV-1 Transcription.

Latent HIV reservoirs persist in people living with HIV despite effective antiretroviral therapy and contribute to rebound viremia upon treatment interruption. Macrophages are an important reservoir cell type, but analysis of agents that modulate latency in macrophages is limited by lack of appropriate in vitro models. We therefore generated an experimental system to investigate this by purifying nonproductively infected human monocyte-derived macrophages (MDM) following in vitro infection with an M-tropic enhanced green fluorescent protein reporter HIV clone and quantified activation of HIV transcription using live-cell fluorescence microscopy. The proportion of HIV-infected MDM was quantified by qPCR detection of HIV DNA, and GFP expression was validated as a marker of productive HIV infection by colabeling of HIV Gag protein. HIV transcription spontaneously reactivated in latently infected MDM at a rate of 0.22% ± 0.04% cells per day (mean ± the standard error of the mean, n = 10 independent donors), producing infectious virions able to infect heterologous T cells in coculture experiments, and both T cells and TZM-bl cells in a cell-free infection system using MDM culture supernatants. Polarization to an M1 phenotype with gamma interferon plus tumor necrosis factor resulted in a 2.3-fold decrease in initial HIV infection of MDM (P < 0.001, n = 8) and a 1.4-fold decrease in spontaneous reactivation (P = 0.025, n = 6), whereas M2 polarization using interleukin-4 prior to infection led to a 1.6-fold decrease in HIV infectivity (P = 0.028, n = 8) but a 2.0-fold increase in the rate of HIV reactivation in latently infected MDM (P = 0.023, n = 6). The latency reversing agents bryostatin and vorinostat, but not panobinostat, significantly induced HIV reactivation in latently infected MDM (P = 0.031 and P = 0.038, respectively, n = 6). IMPORTANCE Agents which modulate latent HIV reservoirs in infected cells are of considerable interest to HIV cure strategies. The present study characterizes a robust, reproducible model enabling quantification of HIV reactivation in primary HIV-infected human MDM which is relatively insensitive to the monocyte donor source and hence suitable for evaluating latency modifiers in MDM. The rate of initial viral infection was greater than the rate of HIV reactivation, suggesting that different mechanisms regulate these processes. HIV reactivation was sensitive to macrophage polarization, suggesting that cellular and tissue environments influence HIV reactivation in different macrophage populations. Importantly, latently infected MDM showed different susceptibilities to certain latency-reversing agents known to be effective in T cells, indicating that dedicated strategies may be required to target latently infected macrophage populations in vivo.

Deficiency of Prebiotic Fiber and Insufficient Signaling Through Gut Metabolite-Sensing Receptors Leads to Cardiovascular Disease.

BACKGROUND: High blood pressure (BP) continues to be a major, poorly controlled but modifiable risk factor for cardiovascular death. Among key Western lifestyle factors, a diet poor in fiber is associated with prevalence of high BP. The impact of lack of prebiotic fiber and the associated mechanisms that lead to higher BP are unknown. Here we show that lack of prebiotic dietary fiber leads to the development of a hypertensinogenic gut microbiota, hypertension and its complications, and demonstrate a role for G-protein coupled-receptors (GPCRs) that sense gut metabolites. METHODS: One hundred seventy-nine mice including C57BL/6J, gnotobiotic C57BL/6J, and knockout strains for GPR41, GPR43, GPR109A, and GPR43/109A were included. C57BL/6J mice were implanted with minipumps containing saline or a slow-pressor dose of angiotensin II (0.25 mg·kg-1·d-1). Mice were fed diets lacking prebiotic fiber with or without addition of gut metabolites called short-chain fatty acids ([SCFA)] produced during fermentation of prebiotic fiber in the large intestine), or high prebiotic fiber diets. Cardiac histology and function, BP, sodium and potassium excretion, gut microbiome, flow cytometry, catecholamines and methylation-wide changes were determined. RESULTS: Lack of prebiotic fiber predisposed mice to hypertension in the presence of a mild hypertensive stimulus, with resultant pathological cardiac remodeling. Transfer of a hypertensinogenic microbiota to gnotobiotic mice recapitulated the prebiotic-deprived hypertensive phenotype, including cardiac manifestations. Reintroduction of SCFAs to fiber-depleted mice had protective effects on the development of hypertension, cardiac hypertrophy, and fibrosis. The cardioprotective effect of SCFAs were mediated via the cognate SCFA receptors GPR43/GPR109A, and modulated L-3,4-dihydroxyphenylalanine levels and the abundance of T regulatory cells regulated by DNA methylation. CONCLUSIONS: The detrimental effects of low fiber Westernized diets may underlie hypertension, through deficient SCFA production and GPR43/109A signaling. Maintaining a healthy, SCFA-producing microbiota is important for cardiovascular health.

Novel Antimuscarinic Antidepressant-like Compounds with Reduced Effects on Cognition.

The cholinergic nervous system has been implicated in mood disorders, evident in the fast-onset antidepressant effects of scopolamine, a potent muscarinic antagonist, in clinical studies. One prominent disadvantage of the use of scopolamine in the treatment of depression is its detrimental effects on cognition, especially as such effects might aggravate cognitive deficits that occur with depression itself. Thus, the identification of antimuscarinic drugs that are free of such detrimental effects may provide an important avenue for the development of novel therapeutics for the management of depression. The present data in rats indicate that a historical muscarinic antagonist, L-687,306, and a muscarinic antagonist of our own design, CJ2100, were as or more effective than scopolamine in antagonizing both the bradycardic effects of the muscarinic agonist arecoline in cardiovascular studies and its discriminative stimulus and rate-decreasing effects in behavioral studies. Additionally, both novel muscarinic antagonists were as effective as scopolamine in decreasing immobility in the forced swim test, a preclinical indicator of potential antidepressant activity. However, at equieffective or even larger doses, they were considerably less disruptive than scopolamine in assays of cognition-related behavior. All three drugs displayed high specificity for the mAChRs with few off-target binding sites, and CJ2100 showed modest affinity across the mAChRs when compared with L-687,306 and scopolamine. These data emphasize the dissimilar pharmacological profiles that are evident across antimuscarinic compounds and the potential utility of novel antagonists for the improved treatment of depression. SIGNIFICANCE STATEMENT: Some clinical studies with the muscarinic antagonist scopolamine document its ability to produce antidepressant effects in patients with mood disorders; however, scopolamine also has well known adverse effects on both autonomic and centrally mediated physiological functions that limit its therapeutic use. This study characterizes the cardiovascular and discriminative stimulus effects of two novel muscarinic antagonists, L-687,306 and CJ2100, that produce antidepressant-like effects in a rodent model (forced swim test) without affecting touchscreen-based cognitive performance (titrating psychomotor vigilance and delayed matching-to-position).

Lung and Eye Disease Develop Concurrently in Supplemental Oxygen-Exposed Neonatal Mice.

Bronchopulmonary dysplasia (BPD) and retinopathy of prematurity (ROP) are two debilitating disorders that develop in preterm infants exposed to supplemental oxygen to prevent respiratory failure. Both can lead to lifelong disabilities, such as chronic obstructive pulmonary disease and vision loss. Due to the lack of a standard experimental model of coincident disease, the underlying associations between BPD and ROP are not well characterized. To address this gap, we used the robust mouse model of oxygen-induced retinopathy exposing C57BL/6 mice to 75% oxygen from postnatal day 7 to 12. The cardinal features of ROP were replicated by this strategy, and the lungs of the same mice were simultaneously examined for evidence of BPD-like lung injury, investigating both the short- and long-term effects of early-life supplemental oxygen exposure. At postnatal days 12 and 18, mild lung disease was evident by histopathologic analysis together with the expected vasculopathy in the inner retina. At later time points, the lung lesion had progressed to severe airspace enlargement and alveolar simplification, with concurrent thinning in the outer layer of the retina. In addition, critical angiogenic oxidative stress and inflammatory factors reported to be dysregulated in ROP were similarly impaired in the lungs. These data shed new light on the interconnectedness of these two neonatal disorders, holding potential for the discovery of novel targets to treat BPD and ROP.

Candida albicans FRE8 encodes a member of the NADPH oxidase family that produces a burst of ROS during fungal morphogenesis.

Until recently, NADPH oxidase (NOX) enzymes were thought to be a property of multicellularity, where the reactive oxygen species (ROS) produced by NOX acts in signaling processes or in attacking invading microbes through oxidative damage. We demonstrate here that the unicellular yeast and opportunistic fungal pathogen Candida albicans is capable of a ROS burst using a member of the NOX enzyme family, which we identify as Fre8. C. albicans can exist in either a unicellular yeast-like budding form or as filamentous multicellular hyphae or pseudohyphae, and the ROS burst of Fre8 begins as cells transition to the hyphal state. Fre8 is induced during hyphal morphogenesis and specifically produces ROS at the growing tip of the polarized cell. The superoxide dismutase Sod5 is co-induced with Fre8 and our findings are consistent with a model in which extracellular Sod5 acts as partner for Fre8, converting Fre8-derived superoxide to the diffusible H2O2 molecule. Mutants of fre8Δ/Δ exhibit a morphogenesis defect in vitro and are specifically impaired in development or maintenance of elongated hyphae, a defect that is rescued by exogenous sources of H2O2. A fre8Δ/Δ deficiency in hyphal development was similarly observed in vivo during C. albicans invasion of the kidney in a mouse model for disseminated candidiasis. Moreover C. albicans fre8Δ/Δ mutants showed defects in a rat catheter model for biofilms. Together these studies demonstrate that like multicellular organisms, C. albicans expresses NOX to produce ROS and this ROS helps drive fungal morphogenesis in the animal host.

Prion protein polymorphisms associated with reduced CWD susceptibility limit peripheral PrPCWD deposition in orally infected white-tailed deer.

BACKGROUND: Chronic wasting disease (CWD) is a prion disease affecting members of the Cervidae family. PrPC primary structures play a key role in CWD susceptibility resulting in extended incubation periods and regulating the propagation of CWD strains. We analyzed the distribution of abnormal prion protein (PrPCWD) aggregates in brain and peripheral organs from orally inoculated white-tailed deer expressing four different PRNP genotypes: Q95G96/Q95G96 (wt/wt), S96/wt, H95/wt and H95/S96 to determine if there are substantial differences in the deposition pattern of PrPCWD between different PRNP genotypes. RESULTS: Although we detected differences in certain brain areas, globally, the different genotypes showed similar PrPCWD deposition patterns in the brain. However, we found that clinically affected deer expressing H95 PrPC, despite having the longest survival periods, presented less PrPCWD immunoreactivity in particular peripheral organs. In addition, no PrPCWD was detected in skeletal muscle of any of the deer. CONCLUSIONS: Our data suggest that expression of H95-PrPC limits peripheral accumulation of PrPCWD as detected by immunohistochemistry. Conversely, infected S96/wt and wt/wt deer presented with similar PrPCWD peripheral distribution at terminal stage of disease, suggesting that the S96-PrPC allele, although delaying CWD progression, does not completely limit the peripheral accumulation of the infectious agent.

Echinocandin Treatment of Candida albicans Biofilms Enhances Neutrophil Extracellular Trap Formation.

The nosocomial pathogen Candida albicans forms biofilms on medical devices that persist in the face of antifungals and host defenses. Echinocandins, the most effective antibiofilm drugs, have recently been shown to augment the activity of neutrophils against biofilms through an unknown mechanism. Here, we show that treatment of C. albicans biofilms with subinhibitory concentrations of echinocandins promotes the formation of neutrophil extracellular traps (NETs), structures of DNA, histones, and antimicrobial proteins with antifungal activity.

The Extracellular Matrix of Candida albicans Biofilms Impairs Formation of Neutrophil Extracellular Traps.

Neutrophils release extracellular traps (NETs) in response to planktonic C. albicans. These complexes composed of DNA, histones, and proteins inhibit Candida growth and dissemination. Considering the resilience of Candida biofilms to host defenses, we examined the neutrophil response to C. albicans during biofilm growth. In contrast to planktonic C. albicans, biofilms triggered negligible release of NETs. Time lapse imaging confirmed the impairment in NET release and revealed neutrophils adhering to hyphae and migrating on the biofilm. NET inhibition depended on an intact extracellular biofilm matrix as physical or genetic disruption of this component resulted in NET release. Biofilm inhibition of NETosis could not be overcome by protein kinase C activation via phorbol myristate acetate (PMA) and was associated with suppression of neutrophil reactive oxygen species (ROS) production. The degree of impaired NET release correlated with resistance to neutrophil attack. The clinical relevance of the role for extracellular matrix in diminishing NET production was corroborated in vivo using a rat catheter model. The C. albicans pmr1Δ/Δ, defective in production of matrix mannan, appeared to elicit a greater abundance of NETs by scanning electron microscopy imaging, which correlated with a decreased fungal burden. Together, these findings show that C. albicans biofilms impair neutrophil response through an inhibitory pathway induced by the extracellular matrix.

Gene delivery of medium chain acyl-coenzyme A dehydrogenase induces physiological cardiac hypertrophy and protects against pathological remodelling.

We previously showed that medium chain acyl-coenzyme A dehydrogenase (MCAD, key regulator of fatty acid oxidation) is positively modulated in the heart by the cardioprotective kinase, phosphoinositide 3-kinase (PI3K(p110α)). Disturbances in cardiac metabolism are a feature of heart failure (HF) patients and targeting metabolic defects is considered a potential therapeutic approach. The specific role of MCAD in the adult heart is unknown. To examine the role of MCAD in the heart and to assess the therapeutic potential of increasing MCAD in the failing heart, we developed a gene therapy tool using recombinant adeno-associated viral vectors (rAAV) encoding MCAD. We hypothesised that increasing MCAD expression may recapitulate the cardioprotective properties of PI3K(p110α). rAAV6:MCAD or rAAV6:control was delivered to healthy adult mice and to mice with pre-existing pathological hypertrophy and cardiac dysfunction due to transverse aortic constriction (TAC). In healthy mice, rAAV6:MCAD induced physiological hypertrophy (increase in heart size, normal systolic function and increased capillary density). In response to TAC (~15 weeks), heart weight/tibia length increased by ~60% in control mice and ~45% in rAAV6:MCAD mice compared with sham. This was associated with an increase in cardiomyocyte cross-sectional area in both TAC groups which was similar. However, hypertrophy in TAC rAAV6:MCAD mice was associated with less fibrosis, a trend for increased capillary density and a more favourable molecular profile compared with TAC rAAV6:control mice. In summary, MCAD induced physiological cardiac hypertrophy in healthy adult mice and attenuated features of pathological remodelling in a cardiac disease model.

Temporal patterns of chronic wasting disease prion excretion in three cervid species.

Chronic wasting disease (CWD) is the only naturally occurring transmissible spongiform encephalopathy affecting free-ranging wildlife populations. Transmission of CWD occurs by direct contact or through contaminated environments; however, little is known about the temporal patterns of CWD prion excretion and shedding in wild cervids. We tested the urine and faeces of three species of captive cervids (elk, mule and white-tailed deer) at 6, 12, 18 and 24 months after oral inoculation to evaluate the temporal, species- and genotype-specific factors affecting the excretion of CWD prions. Although none of the animals exhibited clinical signs of CWD during the study, we determined that all three cervid species were excreting CWD prions by 6 months post-inoculation. Faecal samples were consistently positive for CWD prions for all three cervid species (88 %), and were more likely to be positive than urine samples (28 %). Cervids with genotypes encoding for the prion protein (PRNP) that were considered to be more susceptible to CWD were more likely to excrete CWD prions (94 %) than cervids with genotypes considered to be less susceptible (64 %). All cervids with CWD prions in their urine also had positive faeces (n=5), but the converse was not true. Our study is the first to demonstrate CWD prion excretion in urine by asymptomatic elk and mule deer. Our results indicate that the excretion of CWD prions in faeces and, to a lesser extent, urine may provide an important avenue for depositing prions in the environment.

Peptidylarginine deiminase 2 is required for tumor necrosis factor alpha-induced citrullination and arthritis, but not neutrophil extracellular trap formation.

Citrullination, the post-translational conversion of arginines to citrullines, may contribute to rheumatoid arthritis development given the generation of anti-citrullinated protein antibodies (ACPAs). However, it is not known which peptidylarginine deiminase (PAD) catalyzes the citrullination seen in inflammation. PAD4 exacerbates inflammatory arthritis and is critical for neutrophil extracellular traps (NETs). NETs display citrullinated antigens targeted by ACPAs and thus may be a source of citrullinated protein. However, PAD4 is not required for citrullination in inflamed lungs. PAD2 is important for citrullination in healthy tissues and is present in NETs, but its role in citrullination in the inflamed joint, NETosis and inflammatory arthritis is unknown. Here we use mice with TNFα-induced inflammatory arthritis, a model of rheumatoid arthritis, to identify the roles of PAD2 and PAD4 in citrullination, NETosis, and arthritis. In mice with TNFα-induced arthritis, citrullination in the inflamed ankle was increased as determined by western blot. This increase was unchanged in the ankles of mice that lack PAD4. In contrast, citrullination was nearly absent in the ankles of PAD2-deficient mice. Interestingly, PAD2 was not required for NET formation as assessed by immunofluorescence or for killing of Candida albicans as determined by viability assay. Finally, plasma cell numbers as assessed by flow cytometry, IgG levels quantified by ELISA, and inflammatory arthritis as determined by clinical and pathological scoring were all reduced in the absence of PAD2. Thus, PAD2 contributes to TNFα-induced citrullination and arthritis, but is not required for NETosis. In contrast, PAD4, which is critical for NETosis, is dispensable for generalized citrullination supporting the possibility that NETs may not be a major source of citrullinated protein in arthritis.

Value-based Care Will Flop Without Clinical Integration.

Value-based payment is gaining traction and proving to be a major factor in health care reform. But the success of those value-based models will depend on true clinical integration of providers-not just lip service to coordination.

Longitudinal diffusion tensor imaging after pediatric traumatic brain injury: Impact of age at injury and time since injury on pathway integrity.

Following pediatric traumatic brain injury (TBI), longitudinal diffusion tensor imaging may characterize alterations in initial recovery and subsequent trajectory of white matter development. Our primary aim examined effects of age at injury and time since injury on pathway microstructure in children ages 6-15 scanned 3 and 24 months after TBI. Microstructural values generated using tract-based spatial statistics extracted from core association, limbic, and projection pathways were analyzed using general linear mixed models. Relative to children with orthopedic injury, the TBI group had lower fractional anisotropy (FA) bilaterally in all seven pathways. In left-hemisphere association pathways, school-aged children with TBI had the lowest initial pathway integrity and showed the greatest increase in FA over time suggesting continued development despite incomplete recovery. Adolescents showed limited change in FA and radial diffusivity and had the greatest residual deficit suggesting relatively arrested development. Radial diffusivity was persistently elevated in the TBI group, implicating dysmyelination as a core contributor to chronic post-traumatic neurodegenerative changes. The secondary aim compared FA values over time in the total sample, including participants contributing either one or two scans to the analysis, to the longitudinal cases contributing two scans. For each pathway, FA values and effect sizes were very similar and indicated extremely small differences in measurement of change over time in the total and longitudinal samples. Statistical approaches incorporating missing data may reliably estimate the effects of TBI and provide increased power to identify whether pathways show neurodegeneration, arrested development, or continued growth following pediatric TBI. Hum Brain Mapp 37:3929-3945, 2016. © 2016 Wiley Periodicals, Inc.

Transcriptomic responses to prion disease in rats.

BACKGROUND: Prions diseases are fatal neurodegenerative diseases of mammals. While the molecular responses to prion infection have been extensively characterized in the laboratory mouse, little is known in other rodents. To explore these responses and make comparisons, we generated a prion disease in the laboratory rat by successive passage beginning with mouse RML prions. RESULTS: We describe the accumulation of rat prions, associated pathology and the transcriptional impact throughout the disease course. Comparative transcriptional profiling between laboratory mice and rats suggests that similar molecular and cellular processes are unfolding in response to prion infection. At the level of individual transcripts, however, variability exists between mice and rats and many genes deregulated by prion infection in mice are not affected in rats. CONCLUSION: Our findings detail the molecular responses to prion disease in the rat and highlight the usefulness of comparative approaches to understanding neurodegeneration and prion diseases in particular.

The small molecule raptinal can simultaneously induce apoptosis and inhibit PANX1 activity.

Discovery of new small molecules that can activate distinct programmed cell death pathway is of significant interest as a research tool and for the development of novel therapeutics for pathological conditions such as cancer and infectious diseases. The small molecule raptinal was discovered as a pro-apoptotic compound that can rapidly trigger apoptosis by promoting the release of cytochrome c from the mitochondria and subsequently activating the intrinsic apoptotic pathway. As raptinal is very effective at inducing apoptosis in a variety of different cell types in vitro and in vivo, it has been used in many studies investigating cell death as well as the clearance of dying cells. While examining raptinal as an apoptosis inducer, we unexpectedly identified that in addition to its pro-apoptotic activities, raptinal can also inhibit the activity of caspase-activated Pannexin 1 (PANX1), a ubiquitously expressed transmembrane channel that regulates many cell death-associated processes. By implementing numerous biochemical, cell biological and electrophysiological approaches, we discovered that raptinal can simultaneously induce apoptosis and inhibit PANX1 activity. Surprisingly, raptinal was found to inhibit cleavage-activated PANX1 via a mechanism distinct to other well-described PANX1 inhibitors such as carbenoxolone and trovafloxacin. Furthermore, raptinal also interfered with PANX1-regulated apoptotic processes including the release of the 'find-me' signal ATP, the formation of apoptotic cell-derived extracellular vesicles, as well as NLRP3 inflammasome activation. Taken together, these data identify raptinal as the first compound that can simultaneously induce apoptosis and inhibit PANX1 channels. This has broad implications for the use of raptinal in cell death studies as well as in the development new PANX1 inhibitors.