Glucose-enhanced oxidative stress resistance-A protective anticipatory response that enhances the fitness of Candida albicans during systemic infection.

Most microbes have developed responses that protect them against stresses relevant to their niches. Some that inhabit reasonably predictable environments have evolved anticipatory responses that protect against impending stresses that are likely to be encountered in their niches-termed "adaptive prediction". Unlike yeasts such as Saccharomyces cerevisiae, Kluyveromyces lactis and Yarrowia lipolytica and other pathogenic Candida species we examined, the major fungal pathogen of humans, Candida albicans, activates an oxidative stress response following exposure to physiological glucose levels before an oxidative stress is even encountered. Why? Using competition assays with isogenic barcoded strains, we show that "glucose-enhanced oxidative stress resistance" phenotype enhances the fitness of C. albicans during neutrophil attack and during systemic infection in mice. This anticipatory response is dependent on glucose signalling rather than glucose metabolism. Our analysis of C. albicans signalling mutants reveals that the phenotype is not dependent on the sugar receptor repressor pathway, but is modulated by the glucose repression pathway and down-regulated by the cyclic AMP-protein kinase A pathway. Changes in catalase or glutathione levels do not correlate with the phenotype, but resistance to hydrogen peroxide is dependent on glucose-enhanced trehalose accumulation. The data suggest that the evolution of this anticipatory response has involved the recruitment of conserved signalling pathways and downstream cellular responses, and that this phenotype protects C. albicans from innate immune killing, thereby promoting the fitness of C. albicans in host niches.

Immune cells fold and damage fungal hyphae.

Innate immunity provides essential protection against life-threatening fungal infections. However, the outcomes of individual skirmishes between immune cells and fungal pathogens are not a foregone conclusion because some pathogens have evolved mechanisms to evade phagocytic recognition, engulfment, and killing. For example, Candida albicans can escape phagocytosis by activating cellular morphogenesis to form lengthy hyphae that are challenging to engulf. Through live imaging of C. albicans-macrophage interactions, we discovered that macrophages can counteract this by folding fungal hyphae. The folding of fungal hyphae is promoted by Dectin-1, ß2-integrin, VASP, actin-myosin polymerization, and cell motility. Folding facilitates the complete engulfment of long hyphae in some cases and it inhibits hyphal growth, presumably tipping the balance toward successful fungal clearance.

A randomized study of the safety and pharmacokinetics of GSK3358699, a mononuclear myeloid-targeted bromodomain and extra-terminal domain inhibitor.

AIMS: GSK3358699 is a mononuclear myeloid-targeted bromodomain and extra-terminal domain (BET) family inhibitor which demonstrates immunomodulatory effects in vitro. This phase 1, randomized, first-in-human study evaluated the safety, pharmacokinetics, and pharmacodynamics of GSK3358699 in healthy male participants (NCT03426995). METHODS: Part A (N = 23) included three dose-escalating periods of 1-40 mg of GSK3358699 or placebo in two cohorts in a single ascending-dose crossover design. Part C (N = 25) was planned as an initial dose of 10 mg of GSK3358699 or placebo daily for 14 days followed by selected doses in four sequential cohorts. RESULTS: In part A, exposure to GSK3358699 and its metabolite GSK3206944 generally increased with increasing doses. The median initial half-life ranged from 0.7 to 1.1 (GSK3358699) and 2.1 to 2.9 (GSK3206944) hours after a single dose of 1-40 mg. GSK3206944 concentrations in monocytes were quantifiable at 1-hour post-dose following 10 mg of GSK3358699 and 1 and 4 hours post-dose following 20-40 mg. Mean predicted percentage inhibition of ex vivo lipopolysaccharide-induced monocyte chemoattractant protein (MCP)-1 reached 75% with 40 mg of GSK3358699. GSK3358699 did not inhibit interleukin (IL)-6 and tumour necrosis factor (TNF). The most common adverse event (AE) was headache. Four AEs of nonsustained ventricular tachycardia were observed across parts A and C. One serious AE of atrial fibrillation (part C) required hospitalization. CONCLUSIONS: Single doses of GSK3358699 are generally well tolerated with significant metabolite concentrations detected in target cells. A complete assessment of pharmacodynamics was limited by assay variability. A causal relationship could not be excluded for cardiac-related AEs, resulting in an inability to identify a suitable repeat-dose regimen and study termination.

Safety, pharmacokinetics and pharmacodynamics of a topical SYK inhibitor in cutaneous lupus erythematosus: A double-blind Phase Ib study.

The immunoregulator spleen tyrosine kinase (SYK) is upregulated in cutaneous lupus erythematosus (CLE). This double-blind, multicentre, Phase Ib study evaluated the safety, tolerability, pharmacokinetics, pharmacodynamics and clinical efficacy of the selective SYK inhibitor GSK2646264 in active CLE lesions. Two lesions from each participant (n = 11) were each randomized to topical application of 1% (w/w) GSK2646264 or placebo for 28 days; all participants received GSK2646264 and placebo. The primary endpoint was safety and tolerability of GSK2646264, assessed by adverse event incidence and a skin tolerability test. Secondary endpoints included change from baseline in clinical activity and mRNA expression of interferon-related genes in skin biopsies. Levels of several immune cell markers were evaluated over time. Eight (73%) participants experienced ≥ 1 adverse event (all mild in intensity), and maximal dermal response was similar for GSK2646264 and placebo. The expression of several interferon-related genes, including CXCL10 and OAS1, showed modest decreases from baseline after 28 days of treatment with GSK2646264 compared with placebo. Similar findings were observed for CD3 + T cell and CD11c + dendritic cell levels; however, overall clinical activity remained unchanged with GSK2646264 vs. placebo. Further studies are warranted to assess SYK inhibitors as potential treatment for CLE.

Characterizing infection in anti-neutrophil cytoplasmic antibody-associated vasculitis: results from a longitudinal, matched-cohort data linkage study.

OBJECTIVES: Infection exerts a major burden in ANCA-associated vasculitis (AAV), however, its precise extent and nature remains unclear. In this national study we aimed to longitudinally quantify, characterize and contextualize infection risk in AAV. METHODS: We conducted a multicentre matched cohort study of AAV. Complementary data on infections were retrieved via data linkage with the population-based Scottish microbiological laboratory, hospitalization and primary care prescribing registries. RESULTS: A total of 379 AAV patients and 1859 controls were followed up for a median of 3.5 years (interquartile range 1.9-5.7). During follow-up, the proportions of AAV patients with at least one laboratory-confirmed infection, severe infection and primary care antibiotic prescription were 55.4%, 35.6% and 74.6%, respectively. The risk of infection was higher in AAV than in matched controls {laboratory-confirmed infections: incidence rate ratio [IRR] 7.3 [95% confidence interval (CI) 5.6, 9.6]; severe infections: IRR 4.4 [95% CI 3.3, 5.7]; antibiotic prescriptions: IRR 2.2 [95% CI 1.9, 2.6]}. Temporal trend analysis showed that AAV patients remained at a higher risk of infections throughout the follow-up period, especially year 1. Although the Escherichia genus was the most commonly identified pathogen (16.6% of AAV, 5.5% of controls; P < 0.0001), AAV patients had the highest risk for Herpes [IRR 12.5 (95% CI 3.7, 42.6)] and Candida [IRR 11.4 (95% CI 2.4, 55.4)]. CONCLUSION: AAV patients have up to seven times higher risk of infection than the general population and the overall risk remains significant after 8 years of follow-up. The testing of enhanced short- to medium-term prophylactic antibiotic regimes should be considered.

Belimumab in kidney transplantation: an experimental medicine, randomised, placebo-controlled phase 2 trial.

BACKGROUND: B cells produce alloantibodies and activate alloreactive T cells, negatively affecting kidney transplant survival. By contrast, regulatory B cells are associated with transplant tolerance. Immunotherapies are needed that inhibit B-cell effector function, including antibody secretion, while sparing regulators and minimising infection risk. B lymphocyte stimulator (BLyS) is a cytokine that promotes B-cell activation and has not previously been targeted in kidney transplant recipients. We aimed to determine the safety and activity of an anti-BLyS antibody, belimumab, in addition to standard-of-care immunosuppression in adult kidney transplant recipients. We used an experimental medicine study design with multiple secondary and exploratory endpoints to gain further insight into the effect of belimumab on the generation of de-novo IgG and on the regulatory B-cell compartment. METHODS: We undertook a double-blind, randomised, placebo-controlled phase 2 trial of belimumab, in addition to standard-of-care immunosuppression (basiliximab, mycophenolate mofetil, tacrolimus, and prednisolone) at two centres, Addenbrooke's Hospital, Cambridge, UK, and Guy's and St Thomas' Hospital, London, UK. Participants were eligible if they were aged 18-75 years and receiving a kidney transplant and were planned to receive standard-of-care immunosuppression. Participants were randomly assigned (1:1) to receive either intravenous belimumab 10 mg per kg bodyweight or placebo, given at day 0, 14, and 28, and then every 4 weeks for a total of seven infusions. The co-primary endpoints were safety and change in the concentration of naive B cells from baseline to week 24, both of which were analysed in all patients who received a transplant and at least one dose of drug or placebo (the modified intention-to-treat [mITT] population). This trial has been completed and is registered with ClinicalTrials.gov, NCT01536379, and EudraCT, 2011-006215-56. FINDINGS: Between Sept 13, 2013, and Feb 8, 2015, of 303 patients assessed for eligibility, 28 kidney transplant recipients were randomly assigned to receive belimumab (n=14) or placebo (n=14). 25 patients (12 [86%] patients assigned to the belimumab group and 13 [93%] patients assigned to the placebo group) received a transplant and were included in the mITT population. We observed similar proportions of adverse events in the belimumab and placebo groups, including serious infections (one [8%] of 12 in the belimumab group and five [38%] of 13 in the placebo group during the 6-month on-treatment phase; and none in the belimumab group and two [15%] in the placebo group during the 6-month follow-up). In the on-treatment phase, one patient in the placebo group died because of fatal myocardial infarction and acute cardiac failure. The co-primary endpoint of a reduction in naive B cells from baseline to week 24 was not met. Treatment with belimumab did not significantly reduce the number of naive B cells from baseline to week 24 (adjusted mean difference between the belimumab and placebo treatment groups -34·4 cells per µL, 95% CI -109·5 to 40·7). INTERPRETATION: Belimumab might be a useful adjunct to standard-of-care immunosuppression in renal transplantation, with no major increased risk of infection and potential beneficial effects on humoral alloimmunity. FUNDING: GlaxoSmithKline.

Blocking two-component signalling enhances Candida albicans virulence and reveals adaptive mechanisms that counteract sustained SAPK activation.

The Ypd1 phosphorelay protein is a central constituent of fungal two-component signal transduction pathways. Inhibition of Ypd1 in Saccharomyces cerevisiae and Cryptococcus neoformans is lethal due to the sustained activation of the 'p38-related' Hog1 stress-activated protein kinase (SAPK). As two-component signalling proteins are not found in animals, Ypd1 is considered to be a prime antifungal target. However, a major fungal pathogen of humans, Candida albicans, can survive the concomitant sustained activation of Hog1 that occurs in cells lacking YPD1. Here we show that the sustained activation of Hog1 upon Ypd1 loss is mediated through the Ssk1 response regulator. Moreover, we present evidence that C. albicans survives SAPK activation in the short-term, following Ypd1 loss, by triggering the induction of protein tyrosine phosphatase-encoding genes which prevent the accumulation of lethal levels of phosphorylated Hog1. In addition, our studies reveal an unpredicted, reversible, mechanism that acts to substantially reduce the levels of phosphorylated Hog1 in ypd1Δ cells following long-term sustained SAPK activation. Indeed, over time, ypd1Δ cells become phenotypically indistinguishable from wild-type cells. Importantly, we also find that drug-induced down-regulation of YPD1 expression actually enhances the virulence of C. albicans in two distinct animal infection models. Investigating the underlying causes of this increased virulence, revealed that drug-mediated repression of YPD1 expression promotes hyphal growth both within murine kidneys, and following phagocytosis, thus increasing the efficacy by which C. albicans kills macrophages. Taken together, these findings challenge the targeting of Ypd1 proteins as a general antifungal strategy and reveal novel cellular adaptation mechanisms to sustained SAPK activation.

Calcineurin orchestrates dimorphic transitions, antifungal drug responses and host-pathogen interactions of the pathogenic mucoralean fungus Mucor circinelloides.

Calcineurin plays essential roles in virulence and growth of pathogenic fungi and is a target of the natural products FK506 and Cyclosporine A. In the pathogenic mucoralean fungus Mucor circinelloides, calcineurin mutation or inhibition confers a yeast-locked phenotype indicating that calcineurin governs the dimorphic transition. Genetic analysis in this study reveals that two calcineurin A catalytic subunits (out of three) are functionally diverged. Homology modeling illustrates modes of resistance resulting from amino substitutions in the interface between each calcineurin subunit and the inhibitory drugs. In addition, we show how the dimorphic transition orchestrated by calcineurin programs different outcomes during host-pathogen interactions. For example, when macrophages phagocytose Mucor yeast, subsequent phagosomal maturation occurs, indicating host cells respond appropriately to control the pathogen. On the other hand, upon phagocytosis of spores, macrophages fail to form mature phagosomes. Cytokine production from immune cells differs following exposure to yeast versus spores (which germinate into hyphae). Thus, the morphogenic transition can be targeted as an efficient treatment option against Mucor infection. In addition, genetic analysis (including gene disruption and mutational studies) further strengthens the understanding of calcineurin and provides a foundation to develop antifungal agents targeting calcineurin to deploy against Mucor and other pathogenic fungi.

Rab14 regulates maturation of macrophage phagosomes containing the fungal pathogen Candida albicans and outcome of the host-pathogen interaction.

Avoidance of innate immune defense is an important mechanism contributing to the pathogenicity of microorganisms. The fungal pathogen Candida albicans undergoes morphogenetic switching from the yeast to the filamentous hyphal form following phagocytosis by macrophages, facilitating its escape from the phagosome, which can result in host cell lysis. We show that the intracellular host trafficking GTPase Rab14 plays an important role in protecting macrophages from lysis mediated by C. albicans hyphae. Live-cell imaging of macrophages expressing green fluorescent protein (GFP)-tagged Rab14 or dominant negative Rab14, or with small interfering RNA (siRNA)-mediated knockdown of Rab14, revealed the temporal dynamics of this protein and its influence on the maturation of macrophage phagosomes following the engulfment of C. albicans cells. Phagosomes containing live C. albicans cells became transiently Rab14 positive within 2 min following engulfment. The duration of Rab14 retention on phagosomes was prolonged for hyphal cargo and was directly proportional to hyphal length. Interference with endogenous Rab14 did not affect the migration of macrophages toward C. albicans cells, the rate of engulfment, the overall uptake of fungal cells, or early phagosome processing. However, Rab14 depletion delayed the acquisition of the late phagosome maturation markers LAMP1 and lysosomal cathepsin, indicating delayed formation of a fully bioactive lysosome. This was associated with a significant increase in the level of macrophage killing by C. albicans. Therefore, Rab14 activity promotes phagosome maturation during C. albicans infection but is dysregulated on the phagosome in the presence of the invasive hyphal form, which favors fungal survival and escape.

Role of Dectin-2 for host defense against systemic infection with Candida glabrata.

Although Candida glabrata is an important pathogenic Candida species, relatively little is known about its innate immune recognition. Here, we explore the potential role of Dectin-2 for host defense against C. glabrata. Dectin-2-deficient (Dectin-2(-/-)) mice were found to be more susceptible to C. glabrata infections, showing a defective fungal clearance in kidneys but not in the liver. The increased susceptibility to infection was accompanied by lower production of T helper 1 (Th1) and Th17-derived cytokines by splenocytes of Dectin-2(-/-) mice, while macrophage-derived cytokines were less affected. These defects were associated with a moderate yet significant decrease in phagocytosis of the fungus by the Dectin-2(-/-) macrophages and neutrophils. Neutrophils of Dectin-2(-/-) mice also displayed lower production of reactive oxygen species (ROS) upon challenge with opsonized C. glabrata or C. albicans. This study suggests that Dectin-2 is important in host defense against C. glabrata and provides new insights into the host defense mechanisms against this important fungal pathogen.

The characterisation and determinants of quality of life in ANCA associated vasculitis.

OBJECTIVES: To contextualise and identify the determinants of poor health related quality of life (QOL) among patients with antineutrophil cytoplasm antibody (ANCA) associated vasculitis (AAV). METHODS: A multicentre AAV case-control study was conducted using two matched groups of population and chronic disease controls. Measures of physical and mental QOL as well as putative bio-psychosocial determinants of QOL impairment were collected. Concurrently, putative clinical QOL determinants were recorded. Conditional logistic regression analyses characterised group differences while multivariable logistic regression identified within-case QOL associations which were further quantified using population attributable risks (PAR). RESULTS: Cases (n=410) experienced similar QOL to chronic disease controls (n=318) (physical QOL: OR 0.7, 95% CI 0.4 to 1.1; mental QOL: OR 1.1, 95% CI 0.8 to 1.6). However, they were substantially more likely to report poor QOL compared to general population controls (n=470) (physical QOL: OR 7.0, 95% CI 4.4 to 11.1; mental QOL: OR 2.5, 95% CI 1.7 to 3.6). A few clinical, but many more bio-psychosocial factors were independently associated with poor QOL. In population terms, fatigue was found to be of principal importance (physical QOL: PAR 24.6%; mental QOL: PAR 47.4%). CONCLUSIONS: AAV patients experienced significant QOL impairment compared to the general population, but similar to those with other chronic diseases whose considerable needs are already recognised. Potentially modifiable clinical determinants have been identified; however bio-psychosocial interventions are likely to provide the greater QOL gains in this patient population.

Stage specific assessment of Candida albicans phagocytosis by macrophages identifies cell wall composition and morphogenesis as key determinants.

Candida albicans is a major life-threatening human fungal pathogen. Host defence against systemic Candida infection relies mainly on phagocytosis of fungal cells by cells of the innate immune system. In this study, we have employed video microscopy, coupled with sophisticated image analysis tools, to assess the contribution of distinct C. albicans cell wall components and yeast-hypha morphogenesis to specific stages of phagocytosis by macrophages. We show that macrophage migration towards C. albicans was dependent on the glycosylation status of the fungal cell wall, but not cell viability or morphogenic switching from yeast to hyphal forms. This was not a consequence of differences in maximal macrophage track velocity, but stems from a greater percentage of macrophages pursuing glycosylation deficient C. albicans during the first hour of the phagocytosis assay. The rate of engulfment of C. albicans attached to the macrophage surface was significantly delayed for glycosylation and yeast-locked morphogenetic mutant strains, but enhanced for non-viable cells. Hyphal cells were engulfed at a slower rate than yeast cells, especially those with hyphae in excess of 20 µm, but there was no correlation between hyphal length and the rate of engulfment below this threshold. We show that spatial orientation of the hypha and whether hyphal C. albicans attached to the macrophage via the yeast or hyphal end were also important determinants of the rate of engulfment. Breaking down the overall phagocytic process into its individual components revealed novel insights into what determines the speed and effectiveness of C. albicans phagocytosis by macrophages.

Markers for work disability in anti-neutrophil cytoplasmic antibody-associated vasculitis.

OBJECTIVES: ANCA-associated vasculitis (AAV) commonly affects those of working age. Since survival rates have been transformed by immunotherapeutics, the measurement of other outcomes has become increasingly relevant. Work disability is an important outcome for both patient and society that has yet to be fully evaluated in AAV. We aimed to assess employment status in AAV patients and identify putative predictors of their work disability. METHODS: A cross-sectional study was undertaken. AAV cases were recruited according to consecutive clinic attendance. Subjects completed a questionnaire that determined employment status and other psychosocial measures. Clinical factors were concurrently recorded by the attending physician. From the data of those subjects of working age, a multivariable model was developed using forward stepwise logistic regression to identify the independent associations of work disability, defined by those subjects reporting unemployment secondary to ill-health. Results are expressed as odds ratios (ORs) and 95% CIs. RESULTS: Of the 410 participants (84.4% response rate), 149 (36.7%) were employed, 197 (48.6%) retired and 54 (13.3%) unemployed secondary to ill health. Of those of working age, 26.0% were considered work disabled. Fatigue (OR 7.1, 95% CI 1.5, 33.1), depression (OR 4.4, 95% CI 1.8, 10.8), severe disease damage [Vasculitis Damage Index (VDI) > 4 (OR 3.9, 95% CI 1.01, 14.7)] and being overweight (OR 3.4, 95% CI 1.3, 8.9) were independently associated with their unemployment. CONCLUSION: A quarter of working-age AAV subjects reported unemployment as a result of ill health and are characterized by high levels of fatigue, depression, disease damage and being overweight. These potentially modifiable factors may inform future multidisciplinary interventions aimed at alleviating work disability.

Sialoadhesin promotes rapid proinflammatory and type I IFN responses to a sialylated pathogen, Campylobacter jejuni.

Sialoadhesin (Sn) is a macrophage (Mφ)-restricted receptor that recognizes sialylated ligands on host cells and pathogens. Although Sn is thought to be important in cellular interactions of Mφs with cells of the immune system, the functional consequences of pathogen engagement by Sn are unclear. As a model system, we have investigated the role of Sn in Mφ interactions with heat-killed Campylobacter jejuni expressing a GD1a-like, sialylated glycan. Compared to Sn-expressing bone marrow-derived macrophages (BMDM) from wild-type mice, BMDM from mice either deficient in Sn or expressing a non-glycan-binding form of Sn showed greatly reduced phagocytosis of sialylated C. jejuni. This was accompanied by a strong reduction in MyD88-dependent secretion of TNF-α, IL-6, IL-12, and IL-10. In vivo studies demonstrated that functional Sn was required for rapid TNF-α and IFN-ß responses to i.v.-injected sialylated C. jejuni. Bacteria were captured within minutes after i.v. injection and were associated with Mφs in both liver and spleen. In the spleen, IFN-ß-reactive cells were localized to Sn⁺ Mφs and other cells in the red pulp and marginal zone. Together, these studies demonstrate that Sn plays a key role in capturing sialylated pathogens and promoting rapid proinflammatory cytokine and type I IFN responses.

Impact of secreted glucanases upon the cell surface and fitness of Candida albicans during colonisation and infection.

Host recognition of the pathogen-associated molecular pattern (PAMP), ß-1,3-glucan, plays a major role in antifungal immunity. ß-1,3-glucan is an essential component of the inner cell wall of the opportunistic pathogen Candida albicans. Most ß-1,3-glucan is shielded by the outer cell wall layer of mannan fibrils, but some can become exposed at the cell surface. In response to host signals such as lactate, C. albicans shaves the exposed ß-1,3-glucan from its cell surface, thereby reducing the ability of innate immune cells to recognise and kill the fungus. We have used sets of barcoded xog1 and eng1 mutants to compare the impacts of the secreted ß-glucanases Xog1 and Eng1 upon C. albicans in vitro and in vivo. Flow cytometry of Fc-dectin-1-stained strains revealed that Eng1 plays the greater role in lactate-induced ß-1,3-glucan masking. Transmission electron microscopy and stress assays showed that neither Eng1 nor Xog1 are essential for cell wall maintenance, but the inactivation of either enzyme compromised fungal adhesion to gut and vaginal epithelial cells. Competitive barcode sequencing suggested that neither Eng1 nor Xog1 strongly influence C. albicans fitness during systemic infection or vaginal colonisation in mice. However, the deletion of XOG1 enhanced C. albicans fitness during gut colonisation. We conclude that both Eng1 and Xog1 exert subtle effects on the C. albicans cell surface that influence fungal adhesion to host cells and that affect fungal colonisation in certain host niches.

A CO2 sensing module modulates ß-1,3-glucan exposure in Candida albicans.

Microbial species capable of co-existing with healthy individuals, such as the commensal fungus Candida albicans, exploit multifarious strategies to evade our immune defenses. These strategies include the masking of immunoinflammatory pathogen-associated molecular patterns (PAMPs) at their cell surface. We reported previously that C. albicans actively reduces the exposure of the proinflammatory PAMP, ß-1,3-glucan, at its cell surface in response to host-related signals such as lactate and hypoxia. Here, we show that clinical isolates of C. albicans display phenotypic variability with respect to their lactate- and hypoxia-induced ß-1,3-glucan masking. We have exploited this variability to identify responsive and non-responsive clinical isolates. We then performed RNA sequencing on these isolates to reveal genes whose expression patterns suggested potential association with lactate- or hypoxia-induced ß-1,3-glucan masking. The deletion of two such genes attenuated masking: PHO84 and NCE103. We examined NCE103-related signaling further because NCE103 has been shown previously to encode carbonic anhydrase, which promotes adenylyl cyclase-protein kinase A (PKA) signaling at low CO2 levels. We show that while CO2 does not trigger ß-1,3-glucan masking in C. albicans, the Sch9-Rca1-Nce103 signaling module strongly influences ß-1,3-glucan exposure in response to hypoxia and lactate. In addition to identifying a new regulatory module that controls PAMP exposure in C. albicans, our data imply that this module is important for PKA signaling in response to environmental inputs other than CO2.IMPORTANCEOur innate immune defenses have evolved to protect us against microbial infection in part via receptor-mediated detection of "pathogen-associated molecular patterns" (PAMPs) expressed by invading microbes, which then triggers their immune clearance. Despite this surveillance, many microbial species are able to colonize healthy, immune-competent individuals, without causing infection. To do so, these microbes must evade immunity. The commensal fungus Candida albicans exploits a variety of strategies to evade immunity, one of which involves reducing the exposure of a proinflammatory PAMP (ß-1,3-glucan) at its cell surface. Most of the ß-1,3-glucan is located in the inner layer of the C. albicans cell wall, hidden by an outer layer of mannan fibrils. Nevertheless, some ß-1,3-glucan can become exposed at the fungal cell surface. However, in response to certain specific host signals, such as lactate or hypoxia, C. albicans activates an anticipatory protective response that decreases ß-1,3-glucan exposure, thereby reducing the susceptibility of the fungus to impending innate immune attack. Here, we exploited the natural phenotypic variability of C. albicans clinical isolates to identify strains that do not display the response to ß-1,3-glucan masking signals observed for the reference isolate, SC5314. Then, using genome-wide transcriptional profiling, we compared these non-responsive isolates with responsive controls to identify genes potentially involved in ß-1,3-glucan masking. Mutational analysis of these genes revealed that a sensing module that was previously associated with CO2 sensing also modulates ß-1,3-glucan exposure in response to hypoxia and lactate in this major fungal pathogen of humans.

Explaining fatigue in ANCA-associated vasculitis.

OBJECTIVES: To identify the determinants of fatigue among patients with ANCA-associated vasculitis (AAV). METHODS: A multicentre cross-sectional study was conducted. Subjects fulfilling the European Medicines Agency criteria for granulomatosis with polyangiitis (Wegener's), microscopic polyangiitis and eosinophilic granulomatosis with polyangiitis (Churg-Strauss) were approached according to consecutive clinic attendance and invited to complete a questionnaire assessing fatigue and putative biopsychosocial determinants of this symptom. Concurrently, potential clinical determinants were recorded. Independent associations of fatigue were identified using forward stepwise logistic regression modelling and their overall impact expressed as population attributable risk (PAR). RESULTS: The majority (74.8%) of participants (n = 410) reported high levels of fatigue that were found to be significantly associated with numerous biopsychosocial and clinical factors. Sleep disturbance [odds ratio (OR) 5.3, 95% CI 2.7, 10.5] and pain (OR 3.8, 95% CI 2.0, 7.3) were the strongest independent associations of fatigue and, on a population level, each was more than twice as important as any other putative determinant (PAR 18.1% and 16.5%, respectively). Female gender (OR 2.1, 95% 1.1, 4.0), elevated CRP (OR 3.7, 95% CI 1.7, 8.1) and the dysfunctional coping strategies of behavioural disengagement (OR 2.4, 95% CI 1.04, 5.6) and denial (OR 2.4, 95% CI 0.9, 6.7) were also independently associated with fatigue. CONCLUSION: The data suggest that AAV-related fatigue is multifactorial in origin. Sleep disturbance and pain were found to be most important, although inflammation, as measured by CRP, was also associated. This study has identified potentially modifiable determinants that will inform future interventions aimed at alleviating fatigue.

Erratum to "The nature of the fungal cargo induces significantly different temporal programmes of macrophage phagocytosis" [Cell Surf. 8 (2022) 100082].

[This corrects the article DOI: 10.1016/j.tcsw.2022.100082.].

Fungal spore swelling and germination are restricted by the macrophage phagolysosome.

Many species of medically important fungi are prolific in the formation of asexual spores. Spores undergo a process of active swelling and cell wall remodelling before a germ tube is formed and filamentous growth ensues. Highly elongated germ tubes are known to be difficult to phagocytose and pose particular challenges for immune phagocytes. However, the significance of the earliest stages of spore germination during immune cell interactions has not been investigated and yet this is likely to be important for defence against sporogenous fungal pathogens. We show here that macrophages restrict the early phases of the spore germination process of Aspergillus fumigatus and Mucor circinelloides including the initial phase of spore swelling, spore germination and early polarised growth. Macrophages are therefore adept at retarding germination as well as subsequent vegetative growth which is likely to be critical for immune surveillance and protection against sporulating fungi.

Candida albicans infection inhibits macrophage cell division and proliferation.

The pathogenicity of the opportunistic human fungal pathogen Candida albicans depends on its ability to inhibit effective destruction by host phagocytes. Using live cell video microscopy, we show here for the first time that C. albicans inhibits cell division in macrophages undergoing mitosis. Inhibition of macrophage cell division is dependent on the ability of C. albicans to form hyphae, as it is rarely observed following phagocytosis of UV-killed or morphogenesis-defective mutant Candida. Interestingly, failed cell division following phagocytosis of hyphal C. albicans is surprisingly common, and leads to the formation of large multinuclear macrophages. This raises question as to whether inhibition of macrophage cell division is another virulence attribute of C. albicans or enables host macrophages to contain the pathogen.