Human plasma-like medium (HPLM) induces Cryptococcus neoformans in vivo cell morphologies.

The fungal pathogen Cryptococcus neoformans (C. neoformans) forms yeast cells of different sizes and morphological characteristics during infection. These features are usually not seen in standard laboratory in vitro conditions. Here, we describe in vivo cell morphologies when C. neoformans is grown in human plasma-like medium at 37°C, 5% CO2. We observed mixed-size populations of cells less than 1 µm up to 16.8 µm in cell diameter, increased capsule size, high chitin, and DNA content in larger cells. Our findings show that serum is not required for human plasma-like medium (HPLM)-induced C. neoformans cellular heterogeneity. Thus, this new method offers an opportunity to investigate factors of C. neoformans that mediate pathogenesis or host-pathogen interactions in a physiologically relevant setting.IMPORTANCEWe provide a description of new in vitro culture condition using the human plasma-like medium that supports the formation of the full range of in vivo cell morphologies of C. neoformans.

Characterising phagocytes and measuring phagocytosis from live Galleria mellonella larvae.

Over the last 20 years, the larva of the greater waxmoth, Galleria mellonella, has rapidly increased in popularity as an in vivo mammalian replacement model organism for the study of human pathogens. Experimental readouts of response to infection are most often limited to observing the melanization cascade and quantifying larval death and, whilst transcriptomic and proteomic approaches, and methods to determine microbial load are also used, a more comprehensive toolkit of profiling infection over time could transform the applicability of this model. As an invertebrate, Galleria harbour an innate immune system comprised of both humoral components and a repertoire of innate immune cells - termed haemocytes. Although information on subtypes of haemocytes exists, there are conflicting reports on their exact number and function. Flow cytometry has previously been used to assay Galleria haemocytes, but protocols include both centrifugation and fixation - physical methods which have the potential to affect haemocyte morphology prior to analysis. Here, we present a method for live haemocyte analysis by flow cytometry, revealing that Galleria haemocytes constitute only a single resolvable population, based on relative size or internal complexity. Using fluorescent zymosan particles, we extend our method to show that up to 80% of the Galleria haemocyte population display phagocytic capability. Finally, we demonstrate that the developed assay reliably replicates in vitro data, showing that cell wall ß-1,3-glucan masking by Candida albicans subverts phagocytic responses. As such, our method provides a new tool with which to rapidly assess phagocytosis and understand live infection dynamics in Galleria.

Detailed characterisation of invasive aspergillosis in a murine model of X-linked chronic granulomatous disease shows new insights in infections caused by Aspergillus fumigatus versus Aspergillus nidulans.

Introduction: Invasive aspergillosis (IA) is the most prevalent infectious complication in patients with chronic granulomatous disease (CGD). Yet, understanding of fungal pathogenesis in the CGD host remains limited, particularly with regards to A. nidulans infection. Methods: We have used a murine model of X-linked CGD to investigate how the pathogenesis of IA varies between A. fumigatus and A. nidulans, comparing infection in both X-linked CGD (gp91-/-) mice and their parent C57BL/6 (WT) mice. A 14-colour flow cytometry panel was used to assess the cell dynamics over the course of infection, with parallel assessment of pulmonary cytokine production and lung histology. Results: We observed a lack of association between pulmonary pathology and infection outcome in gp91-/- mice, with no significant mortality in A. nidulans infected mice. An overwhelming and persistent neutrophil recruitment and IL-1 release in gp91-/- mice following both A. fumigatus and A. nidulans infection was observed, with divergent macrophage, dendritic cell and eosinophil responses and distinct cytokine profiles between the two infections. Conclusion: We have provided an in-depth characterisation of the immune response to pulmonary aspergillosis in an X-linked CGD murine model. This provides the first description of distinct pulmonary inflammatory environments in A. fumigatus and A. nidulans infection in X-linked CGD and identifies several new avenues for further research.

Nature of ß-1,3-Glucan-Exposing Features on Candida albicans Cell Wall and Their Modulation.

Candida albicans exists as a commensal of mucosal surfaces and the gastrointestinal tract without causing pathology. However, this fungus is also a common cause of mucosal and systemic infections when antifungal immune defenses become compromised. The activation of antifungal host defenses depends on the recognition of fungal pathogen-associated molecular patterns (PAMPs), such as ß-1,3-glucan. In C. albicans, most ß-1,3-glucan is present in the inner cell wall, concealed by the outer mannan layer, but some ß-1,3-glucan becomes exposed at the cell surface. In response to host signals, such as lactate, C. albicans induces the Xog1 exoglucanase, which shaves exposed ß-1,3-glucan from the cell surface, thereby reducing phagocytic recognition. We show here that ß-1,3-glucan is exposed at bud scars and punctate foci on the lateral wall of yeast cells, that this exposed ß-1,3-glucan is targeted during phagocytic attack, and that lactate-induced masking reduces ß-1,3-glucan exposure at bud scars and at punctate foci. ß-1,3-Glucan masking depends upon protein kinase A (PKA) signaling. We reveal that inactivating PKA, or its conserved downstream effectors, Sin3 and Mig1/Mig2, affects the amounts of the Xog1 and Eng1 glucanases in the C. albicans secretome and modulates ß-1,3-glucan exposure. Furthermore, perturbing PKA, Sin3, or Mig1/Mig2 attenuates the virulence of lactate-exposed C. albicans cells in Galleria. Taken together, the data are consistent with the idea that ß-1,3-glucan masking contributes to Candida pathogenicity. IMPORTANCE Microbes that coexist with humans have evolved ways of avoiding or evading our immunological defenses. These include the masking by these microbes of their "pathogen-associated molecular patterns" (PAMPs), which are recognized as "foreign" and used to activate protective immunity. The commensal fungus Candida albicans masks the proinflammatory PAMP ß-1,3-glucan, which is an essential component of its cell wall. Most of this ß-1,3-glucan is hidden beneath an outer layer of the cell wall on these microbes, but some can become exposed at the fungal cell surface. Using high-resolution confocal microscopy, we examine the nature of the exposed ß-1,3-glucan at C. albicans bud scars and at punctate foci on the lateral cell wall, and we show that these features are targeted by innate immune cells. We also reveal that downstream effectors of protein kinase A (Mig1/Mig2, Sin3) regulate the secretion of major glucanases, modulate the levels of ß-1,3-glucan exposure, and influence the virulence of C. albicans in an invertebrate model of systemic infection. Our data support the view that ß-1,3-glucan masking contributes to immune evasion and the virulence of a major fungal pathogen of humans.

Impact of changes at the Candida albicans cell surface upon immunogenicity and colonisation in the gastrointestinal tract.

The immunogenicity of Candida albicans cells is influenced by changes in the exposure of microbe-associated molecular patterns (MAMPs) on the fungal cell surface. Previously, the degree of exposure on the C. albicans cell surface of the immunoinflammatory MAMP ß-(1,3)-glucan was shown to correlate inversely with colonisation levels in the gastrointestinal (GI) tract. This is important because life-threatening systemic candidiasis in critically ill patients often arises from translocation of C. albicans strains present in the patient's GI tract. Therefore, using a murine model, we have examined the impact of gut-related factors upon ß-glucan exposure and colonisation levels in the GI tract. The degree of ß-glucan exposure was examined by imaging flow cytometry of C. albicans cells taken directly from GI compartments, and compared with colonisation levels. Fungal ß-glucan exposure was lower in the cecum than the small intestine, and fungal burdens were correspondingly higher in the cecum. This inverse correlation did not hold for the large intestine. The gut fermentation acid, lactate, triggers ß-glucan masking in vitro, leading to attenuated anti-Candida immune responses. Additional fermentation acids are present in the GI tract, including acetate, propionate, and butyrate. We show that these acids also influence ß-glucan exposure on C. albicans cells in vitro and, like lactate, they influence ß-glucan exposure via Gpr1/Gpa2-mediated signalling. Significantly, C. albicans gpr1Δ gpa2Δ cells displayed elevated ß-glucan exposure in the large intestine and a corresponding decrease in fungal burden, consistent with the idea that Gpr1/Gpa2-mediated ß-glucan masking influences colonisation of this GI compartment. Finally, extracts from the murine gut and culture supernatants from the mannan grazing gut anaerobe Bacteroides thetaiotaomicron promote ß-glucan exposure at the C. albicans cell surface. Therefore, the local microbiota influences ß-glucan exposure levels directly (via mannan grazing) and indirectly (via fermentation acids), whilst ß-glucan masking appears to promote C. albicans colonisation of the murine large intestine.

MelLec Exacerbates the Pathogenesis of Aspergillus fumigatus-Induced Allergic Inflammation in Mice.

Environmental factors, particularly fungi, influence the pathogenesis of allergic airway inflammation, but the mechanisms underlying these effects are still unclear. Melanin is one fungal component which is thought to modulate pulmonary inflammation. We recently identified a novel C-type lectin receptor, MelLec (Clec1a), which recognizes fungal 1,8-dihydroxynaphthalene (DHN)-melanin and is able to regulate inflammatory responses. Here we show that MelLec promotes pulmonary allergic inflammation and drives the development of Th17 T-cells in response to spores of Aspergillus fumigatus. Unexpectedly, we found that MelLec deficiency was protective, with MelLec-/- animals showing normal weight gain and significantly reduced pulmonary inflammation in our allergic model. The lungs of treated MelLec-/- mice displayed significantly reduced inflammatory foci and reduced bronchial wall thickening, which correlated with a reduced cellular influx (particularly neutrophils and inflammatory monocytes) and levels of inflammatory cytokines and chemokines. Notably, fungal burdens were increased in MelLec-/- animals, without apparent adverse effects, and there were no alterations in the survival of these mice. Characterization of the pulmonary T-cell populations, revealed a significant reduction in Th17 cells, and no alterations in Th2, Th1 or Treg cells. Thus, our data reveal that while MelLec is required to control pulmonary fungal burden, the inflammatory responses mediated by this receptor negatively impact the animal welfare in this allergic model.

Characterization of antifungal C-type lectin receptor expression on murine epithelial and endothelial cells in mucosal tissues.

Our data reveal that selection of enzymes for generating single cell suspensions from murine tissues influences detection of surface expression of antifungal CLRs. Using a method that most preserves receptor expression, we show that non-myeloid expression of antifungal CLRs is limited to MelLec on endothelial cells in murine mucosal tissues.

Hydrocarbon-Degrading Bacteria Found Tightly Associated with the 50-70 µm Cell-Size Population of Eukaryotic Phytoplankton in Surface Waters of a Northeast Atlantic Region.

The surface of marine eukaryotic phytoplankton can harbour communities of hydrocarbon-degrading bacteria; however, this algal-bacterial association has, hitherto, been only examined with non-axenic laboratory cultures of micro-algae. In this study, we isolated an operationally-defined community of phytoplankton, of cell size 50-70 µm, from a natural community in sea surface waters of a subarctic region in the northeast Atlantic. Using MiSeq 16S rRNA sequencing, we identified several recognized (Alcanivorax, Marinobacter, Oleispira, Porticoccus, Thalassospira) and putative hydrocarbon degraders (Colwelliaceae, Vibrionaceae) tightly associated with the phytoplankton population. We combined fluorescence in situ hybridisation with flow-cytometry (FISH-Flow) to examine the association of Marinobacter with this natural eukaryotic phytoplankton population. About 1.5% of the phytoplankton population contained tightly associated Marinobacter. The remaining Marinobacter population were loosely associated with either eukaryotic phytoplankton cells or non-chlorophyll particulate material. This work is the first to show the presence of obligate, generalist and putative hydrocarbonoclastic bacteria associated with natural populations of eukaryotic phytoplankton directly from sea surface water samples. It also highlights the suitability of FISH-Flow for future studies to examine the spatial and temporal structure and dynamics of these and other algal-bacterial associations in natural seawater samples.

A Weakened Immune Response to Synthetic Exo-Peptides Predicts a Potential Biosecurity Risk in the Retrieval of Exo-Microorganisms.

The discovery of liquid water at several locations in the solar system raises the possibility that microbial life may have evolved outside Earth and as such could be accidently introduced into the Earth's ecosystem. Unusual sugars or amino acids, like non-proteinogenic isovaline and α-aminoisobutyric acid that are vanishingly rare or absent from life forms on Earth, have been found in high abundance on non-terrestrial carbonaceous meteorites. It is therefore conceivable that exo-microorganisms might contain proteins that include these rare amino acids. We therefore asked whether the mammalian immune system would be able to recognize and induce appropriate immune responses to putative proteinaceous antigens that include these rare amino acids. To address this, we synthesised peptide antigens based on a backbone of ovalbumin and introduced isovaline and α-aminoisobutyric acid residues and demonstrated that these peptides can promote naïve OT-I cell activation and proliferation, but did so less efficiently than the canonical peptides. This is relevant to the biosecurity of missions that may retrieve samples from exoplanets and moons that have conditions that may be permissive for life, suggesting that accidental contamination and exposure to exo-microorganisms with such distinct proteomes might pose an immunological challenge.

Fast field-cycling magnetic resonance detection of intracellular ultra-small iron oxide particles in vitro: Proof-of-concept.

PURPOSE: Inflammation is central in disease pathophysiology and accurate methods for its detection and quantification are increasingly required to guide diagnosis and therapy. Here we explored the ability of Fast Field-Cycling Magnetic Resonance (FFC-MR) in quantifying the signal of ultra-small superparamagnetic iron oxide particles (USPIO) phagocytosed by J774 macrophage-like cells as a proof-of-principle. METHODS: Relaxation rates were measured in suspensions of J774 macrophage-like cells loaded with USPIO (0-200 µg/ml Fe as ferumoxytol), using a 0.25 T FFC benchtop relaxometer and a human whole-body, in-house built 0.2 T FFC-MR prototype system with a custom test tube coil. Identical non-imaging, saturation recovery pulse sequence with 90° flip angle and 20 different evolution fields selected logarithmically between 80 µT and 0.2 T (3.4 kHz and 8.51 MHz proton Larmor frequency [PLF] respectively). Results were compared with imaging flow cytometry quantification of side scatter intensity and USPIO-occupied cell area. A reference colorimetric iron assay was used. RESULTS: The T1 dispersion curves derived from FFC-MR were excellent in detecting USPIO at all concentrations examined (0-200 µg/ml Fe as ferumoxytol) vs. control cells, p ≤ 0.001. FFC-NMR was capable of reliably detecting cellular iron content as low as 1.12 ng/µg cell protein, validated using a colorimetric assay. FFC-MR was comparable to imaging flow cytometry quantification of side scatter intensity but superior to USPIO-occupied cell area, the latter being only sensitive at exposures ≥ 10 µg/ml USPIO. CONCLUSIONS: We demonstrated for the first time that FFC-MR is capable of quantitative assessment of intra-cellular iron which will have important implications for the use of USPIO in a variety of biological applications, including the study of inflammation.

Immediate visualization of recombination events and chromosome segregation defects in fission yeast meiosis.

Schizosaccharomyces pombe, also known as fission yeast, is an established model for studying chromosome biological processes. Over the years, research employing fission yeast has made important contributions to our knowledge about chromosome segregation during meiosis, as well as meiotic recombination and its regulation. Quantification of meiotic recombination frequency is not a straightforward undertaking, either requiring viable progeny for a genetic plating assay, or relying on laborious Southern blot analysis of recombination intermediates. Neither of these methods lends itself to high-throughput screens to identify novel meiotic factors. Here, we establish visual assays novel to Sz. pombe for characterizing chromosome segregation and meiotic recombination phenotypes. Genes expressing red, yellow, and/or cyan fluorophores from spore-autonomous promoters have been integrated into the fission yeast genomes, either close to the centromere of chromosome 1 to monitor chromosome segregation, or on the arm of chromosome 3 to form a genetic interval at which recombination frequency can be determined. The visual recombination assay allows straightforward and immediate assessment of the genetic outcome of a single meiosis by epi-fluorescence microscopy without requiring tetrad dissection. We also demonstrate that the recombination frequency analysis can be automatized by utilizing imaging flow cytometry to enable high-throughput screens. These assays have several advantages over traditional methods for analyzing meiotic phenotypes.

Repurposing of idebenone as a potential anti-cancer agent.

Glioblastoma (GB) represents the most common and aggressive form of malignant primary brain tumour associated with high rates of morbidity and mortality. In the present study, we considered the potential use of idebenone (IDE), a Coenzyme Q10 analogue, as a novel chemotherapeutic agent for GB. On two GB cell lines, U373MG and U87MG, IDE decreased the viable cell number and enhanced the cytotoxic effects of two known anti-proliferative agents: temozolomide and oxaliplatin. IDE also affected the clonogenic and migratory capacity of both GB cell lines, at 25 and 50 µM, a concentration equivalent to that transiently reached in plasma after oral intake that is deemed safe for humans. p21 protein expression was decreased in both cell lines, indicating that IDE likely exerts its effects through cell cycle dysregulation, and this was confirmed in U373MG cells only by flow cytometric cell cycle analysis which showed S-phase arrest. Caspase-3 protein expression was also significantly decreased in U373MG cells indicating IDE-induced apoptosis that was confirmed by flow cytometric Annexin V/propidium iodide staining. No major decrease in caspase-3 expression was observed in U87MG cells nor apoptosis as observed by flow cytometry analysis. Overall, the present study demonstrates that IDE has potential as an anti-proliferative agent for GB by interfering with several features of glioma pathogenesis such as proliferation and migration, and hence might be a drug that could be repurposed for aiding cancer treatments. Furthermore, the synergistic combinations of IDE with other agents aimed at different pathways involved in this type of cancer are promising.

Myocardial and Systemic Inflammation in Acute Stress-Induced (Takotsubo) Cardiomyopathy.

BACKGROUND: Acute stress-induced (takotsubo) cardiomyopathy can result in a heart failure phenotype with a prognosis comparable with that of myocardial infarction. In this study, we hypothesized that inflammation is central to the pathophysiology and natural history of takotsubo cardiomyopathy. METHODS: In a multicenter study, we prospectively recruited 55 patients with takotsubo cardiomyopathy and 51 age-, sex-, and comorbidity-matched control subjects. During the index event and at the 5-month follow-up, patients with takotsubo cardiomyopathy underwent multiparametric cardiac magnetic resonance imaging, including ultrasmall superparamagnetic particles of iron oxide (USPIO) enhancement for detection of inflammatory macrophages in the myocardium. Blood monocyte subpopulations and serum cytokines were assessed as measures of systemic inflammation. Matched control subjects underwent investigation at a single time point. RESULTS: Subjects were predominantly middle-aged (64±14 years) women (90%). Compared with control subjects, patients with takotsubo cardiomyopathy had greater USPIO enhancement (expressed as the difference between pre-USPIO and post-USPIO T2*) in both ballooning (14.3±0.6 milliseconds versus 10.5±0.9 milliseconds; P<0.001) and nonballooning (12.9±0.6 milliseconds versus 10.5±0.9 milliseconds; P=0.02) left ventricular myocardial segments. Serum interleukin-6 (23.1±4.5 pg/mL versus 6.5±5.8 pg/mL; P<0.001) and chemokine (C-X-C motif) ligand 1 (1903±168 pg/mL versus 1272±177 pg/mL; P=0.01) concentrations and classic CD14++CD16- monocytes (90±0.5% versus 87±0.9%; P=0.01) were also increased whereas intermediate CD14++CD16+ (5.4±0.3% versus 6.9±0.6%; P=0.01) and nonclassic CD14+CD16++ (2.7±0.3% versus 4.2±0.5%; P=0.006) monocytes were reduced in patients with takotsubo cardiomyopathy. At 5 months, USPIO enhancement was no longer detectable in the left ventricular myocardium, although persistent elevations in serum interleukin-6 concentrations ( P=0.009) and reductions in intermediate CD14++CD16+ monocytes (5.6±0.4% versus 6.9±0.6%; P=0.01) remained. CONCLUSIONS: We demonstrate for the first time that takotsubo cardiomyopathy is characterized by a myocardial macrophage inflammatory infiltrate, changes in the distribution of monocyte subsets, and an increase in systemic proinflammatory cytokines. Many of these changes persisted for at least 5 months, suggesting a low-grade chronic inflammatory state. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov . Unique identifier: NCT02897739.

The Cryptococcus neoformans Titan cell is an inducible and regulated morphotype underlying pathogenesis.

Fungal cells change shape in response to environmental stimuli, and these morphogenic transitions drive pathogenesis and niche adaptation. For example, dimorphic fungi switch between yeast and hyphae in response to changing temperature. The basidiomycete Cryptococcus neoformans undergoes an unusual morphogenetic transition in the host lung from haploid yeast to large, highly polyploid cells termed Titan cells. Titan cells influence fungal interaction with host cells, including through increased drug resistance, altered cell size, and altered Pathogen Associated Molecular Pattern exposure. Despite the important role these cells play in pathogenesis, understanding the environmental stimuli that drive the morphological transition, and the molecular mechanisms underlying their unique biology, has been hampered by the lack of a reproducible in vitro induction system. Here we demonstrate reproducible in vitro Titan cell induction in response to environmental stimuli consistent with the host lung. In vitro Titan cells exhibit all the properties of in vivo generated Titan cells, the current gold standard, including altered capsule, cell wall, size, high mother cell ploidy, and aneuploid progeny. We identify the bacterial peptidoglycan subunit Muramyl Dipeptide as a serum compound associated with shift in cell size and ploidy, and demonstrate the capacity of bronchial lavage fluid and bacterial co-culture to induce Titanisation. Additionally, we demonstrate the capacity of our assay to identify established (cAMP/PKA) and previously undescribed (USV101) regulators of Titanisation in vitro. Finally, we investigate the Titanisation capacity of clinical isolates and their impact on disease outcome. Together, these findings provide new insight into the environmental stimuli and molecular mechanisms underlying the yeast-to-Titan transition and establish an essential in vitro model for the future characterization of this important morphotype.

Recognition of DHN-melanin by a C-type lectin receptor is required for immunity to Aspergillus.

Resistance to infection is critically dependent on the ability of pattern recognition receptors to recognize microbial invasion and induce protective immune responses. One such family of receptors are the C-type lectins, which are central to antifungal immunity. These receptors activate key effector mechanisms upon recognition of conserved fungal cell-wall carbohydrates. However, several other immunologically active fungal ligands have been described; these include melanin, for which the mechanism of recognition is hitherto undefined. Here we identify a C-type lectin receptor, melanin-sensing C-type lectin receptor (MelLec), that has an essential role in antifungal immunity through recognition of the naphthalene-diol unit of 1,8-dihydroxynaphthalene (DHN)-melanin. MelLec recognizes melanin in conidial spores of Aspergillus fumigatus as well as in other DHN-melanized fungi. MelLec is ubiquitously expressed by CD31+ endothelial cells in mice, and is also expressed by a sub-population of these cells that co-express epithelial cell adhesion molecule and are detected only in the lung and the liver. In mouse models, MelLec was required for protection against disseminated infection with A. fumigatus. In humans, MelLec is also expressed by myeloid cells, and we identified a single nucleotide polymorphism of this receptor that negatively affected myeloid inflammatory responses and significantly increased the susceptibility of stem-cell transplant recipients to disseminated Aspergillus infections. MelLec therefore recognizes an immunologically active component commonly found on fungi and has an essential role in protective antifungal immunity in both mice and humans.

Elevated catalase expression in a fungal pathogen is a double-edged sword of iron.

Most fungal pathogens of humans display robust protective oxidative stress responses that contribute to their pathogenicity. The induction of enzymes that detoxify reactive oxygen species (ROS) is an essential component of these responses. We showed previously that ectopic expression of the heme-containing catalase enzyme in Candida albicans enhances resistance to oxidative stress, combinatorial oxidative plus cationic stress, and phagocytic killing. Clearly ectopic catalase expression confers fitness advantages in the presence of stress, and therefore in this study we tested whether it enhances fitness in the absence of stress. We addressed this using a set of congenic barcoded C. albicans strains that include doxycycline-conditional tetON-CAT1 expressors. We show that high basal catalase levels, rather than CAT1 induction following stress imposition, reduce ROS accumulation and cell death, thereby promoting resistance to acute peroxide or combinatorial stress. This conclusion is reinforced by our analyses of phenotypically diverse clinical isolates and the impact of stochastic variation in catalase expression upon stress resistance in genetically homogeneous C. albicans populations. Accordingly, cat1Δ cells are more sensitive to neutrophil killing. However, we find that catalase inactivation does not attenuate C. albicans virulence in mouse or invertebrate models of systemic candidiasis. Furthermore, our direct comparisons of fitness in vitro using isogenic barcoded CAT1, cat1Δ and tetON-CAT1 strains show that, while ectopic catalase expression confers a fitness advantage during peroxide stress, it confers a fitness defect in the absence of stress. This fitness defect is suppressed by iron supplementation. Also high basal catalase levels induce key iron assimilatory functions (CFL5, FET3, FRP1, FTR1). We conclude that while high basal catalase levels enhance peroxide stress resistance, they place pressure on iron homeostasis through an elevated cellular demand for iron, thereby reducing the fitness of C. albicans in iron-limiting tissues within the host.

Transporters for Antiretroviral Drugs in Colorectal CD4+ T Cells and Circulating α4ß7 Integrin CD4+ T Cells: Implications for HIV Microbicides.

CD4+ T lymphocytes in the colorectal mucosa are key in HIV-1 transmission and dissemination. As such they are also the primary target for antiretroviral (ARV)-based rectal microbicides for pre-exposure prophylaxis. Drug transporters expressed in mucosal CD4+ T cells determine ARV distribution across the cell membrane and, most likely, efficacy of microbicides. We describe transporters for antiretroviral drugs in colorectal mucosal CD4+ T lymphocytes and compare gene expression with circulating α4ß7+CD4+ T cells, which traffic to the intestine and have been shown to be preferentially infected by HIV-1. Purified total CD4+ T cells were obtained from colorectal tissue and blood samples by magnetic separation. CD4+ T cells expressing α4ß7 integrin were isolated by fluorescence-activated cell sorting from peripheral blood mononuclear cells of healthy volunteers. Expressions of 15 efflux and uptake drug transporter genes were quantified using Taqman qPCR assays. Expression of efflux transporters MRP3, MRP5, and BCRP and uptake transporter CNT2 were significantly higher in colorectal CD4+ T cells compared to circulating CD4+ T cells (p = 0.01-0.03). Conversely, circulating α4ß7+CD4+ T cells demonstrated significantly higher expression of OATPD compared to colorectal CD4+ T cells (p = 0.001). To the best of our knowledge this is the first report of drug transporter gene expression in colorectal CD4+ and peripheral α4ß7+CD4+ T cells. The qualitative and quantitative differences in drug transporter gene expression profiles between α4ß7+CD4+ T cells and total mucosal CD4+ T cells may have significant implications for the efficacy of rectally delivered ARV-microbicides. Most notably, we have identified efflux drug transporters that could be targeted by selective inhibitors or beneficial drug-drug interactions to enhance intracellular accumulation of antiretroviral drugs.

Older Patients Are Immunocompromised by Cytokine Depletion and Loss of Innate Immune Function After HIP Fracture Surgery.

PURPOSE/INTRODUCTION: We have examined the immune status of elderly patients who underwent surgery for a hip fracture, an injury associated with poor postoperative outcomes, to identify specific immune defects. METHODS: In a cohort observational study, 16 patients undergoing surgery for hip fractures had immune function evaluation prior to surgery, and then at 3 and 7 days postoperatively, using flow cytometry for phenotype and for monocyte and granulocyte phagocytic function and respiratory burst. Serum samples were stored and batch analyzed using a human cytokine 25-plex panel. RESULTS: We report significant loss of innate immune function, related specifically to reduced granulocyte numbers by day 7 (P < .0001, flow cytometry; P < .05 white blood cells), and although granulocyte ability to take up opsonized Escherichia coli was increased (P < .05), the ability of those cells to generate a respiratory burst was reduced at days 3 and 7 (P < .05). Monocyte respiratory burst was also significantly reduced (P < .05). Serum cytokine levels indicated very poor T-cell function. CONCLUSION: We have demonstrated that the antimicrobial immune response is profoundly reduced after surgery in elderly patients with hip fractures. The effect was sustained up to 7 days postoperatively, identifying these patients as particularly vulnerable to bacterial infections.