ABSTRACT
Invasive fungal disease accounts for about 3.8â million deaths annually, an unacceptable rate that urgently prompts the discovery of new knowledge-driven treatments. We report the use of camelid single-domain nanobodies (Nbs) against fungal ß-1,3-glucanosyltransferases (Gel) involved in ß-1,3-glucan transglycosylation. Crystal structures of two Nbs with Gel4 from Aspergillus fumigatus revealed binding to a dissimilar CBM43 domain and a highly conserved catalytic domain across fungal species, respectively. Anti-Gel4 active site Nb3 showed significant antifungal efficacy in vitro and in vivo prophylactically and therapeutically against different A. fumigatus and Cryptococcus neoformans isolates, reducing the fungal burden and disease severity, thus significantly improving immunocompromised animal survival. Notably, C. deneoformans (serotypeâ D) strains were more susceptible to Nb3 and genetic Gel deletion than C. neoformans (serotype A) strains, indicating a key role for ß-1,3-glucan remodelling in C. deneoformans survival. These findings add new insight about the role of ß-1,3-glucan in fungal biology and demonstrate the potential of nanobodies in targeting fungal enzymes to combat invasive fungal diseases.
Subject(s)
Aspergillus fumigatus , Catalytic Domain , Single-Domain Antibodies , Single-Domain Antibodies/chemistry , Single-Domain Antibodies/immunology , Single-Domain Antibodies/pharmacology , Aspergillus fumigatus/immunology , Aspergillus fumigatus/enzymology , Cryptococcus neoformans/enzymology , Cryptococcus neoformans/immunology , Antifungal Agents/chemistry , Antifungal Agents/pharmacology , Animals , Mice , Glucan Endo-1,3-beta-D-GlucosidaseABSTRACT
Cellular mRNA levels, particularly under stress conditions, can be finely regulated by the coordinated action of transcription and degradation processes. Elements of the 5'-3' mRNA degradation pathway, functionally associated with the exonuclease Xrn1, can bind to nuclear chromatin and modulate gene transcription. Within this group are the so-called decapping activators, including Pat1, Dhh1, and Lsm1. In this work, we have investigated the role of Pat1 in the yeast adaptive transcriptional response to cell wall stress. Thus, we demonstrated that in the absence of Pat1, the transcriptional induction of genes regulated by the Cell Wall Integrity MAPK pathway was significantly affected, with no effect on the stability of these transcripts. Furthermore, under cell wall stress conditions, Pat1 is recruited to Cell Wall Integrity-responsive genes in parallel with the RNA Pol II complex, participating both in pre-initiation complex assembly and transcriptional elongation. Indeed, strains lacking Pat1 showed lower recruitment of the transcription factor Rlm1, less histone H3 displacement at Cell Wall Integrity gene promoters, and impaired recruitment and progression of RNA Pol II. Moreover, Pat1 and the MAPK Slt2 occupied the coding regions interdependently. Our results support the idea that Pat1 and presumably other decay factors behave as transcriptional regulators of Cell Wall Integrity-responsive genes under cell wall stress conditions.
Subject(s)
Cell Wall , Endoribonucleases , Gene Expression Regulation, Fungal , MAP Kinase Signaling System , RNA Stability , RNA-Binding Proteins , Saccharomyces cerevisiae Proteins , Saccharomyces cerevisiae , Cell Wall/enzymology , Cell Wall/genetics , Endoribonucleases/metabolism , Endoribonucleases/genetics , MADS Domain Proteins/metabolism , RNA Polymerase II/metabolism , RNA Polymerase II/genetics , RNA, Messenger/genetics , RNA, Messenger/metabolism , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae/metabolism , Saccharomyces cerevisiae Proteins/metabolism , Saccharomyces cerevisiae Proteins/genetics , Transcription, GeneticABSTRACT
Conditions altering the yeast cell wall lead to the activation of an adaptive transcriptional response mainly governed by the cell wall integrity (CWI) mitogen-activated protein kinase (MAPK) pathway. Two high-throughput screenings were developed using the yTHC collection of yeast conditional mutant strains to systematically identify essential genes related to cell wall integrity, and those required for the transcriptional program elicited by cell wall stress. Depleted expression of 52 essential genes resulted in hypersensitivity to the dye Calcofluor white, with chromatin organization, Golgi vesicle transport, rRNA processing, and protein glycosylation processes, as the most highly representative functional groups. Via a flow cytometry-based quantitative assay using a CWI reporter plasmid, 97 strains exhibiting reduced gene-reporter expression levels upon stress were uncovered, highlighting genes associated with RNA metabolism, transcription/translation, protein degradation, and chromatin organization. This screening also led to the discovery of 41 strains displaying a basal increase in CWI-associated gene expression, including mainly putative cell wall-related genes. Interestingly, several members of the RSC chromatin remodelling complex were uncovered in both screenings. Notably, Rsc9 was necessary to regulate the gene expression of CWI-related genes both under stress and non-stress conditions, suggesting distinct requirements of the RSC complex for remodelling particular genes.
ABSTRACT
Peer production online communities are groups of people that collaboratively engage in the building of common resources such as wikis and open source projects. In such communities, participation is highly unequal: few people concentrate the majority of the workload, while the rest provide irregular and sporadic contributions. The distribution of participation is typically characterized as a power law distribution. However, recent statistical studies on empirical data have challenged the power law dominance in other domains. This work critically examines the assumption that the distribution of participation in wikis follows such distribution. We use statistical tools to analyse over 6,000 wikis from Wikia/Fandom, the largest wiki repository. We study the empirical distribution of each wiki comparing it with different well-known skewed distributions. The results show that the power law performs poorly, surpassed by three others with a more moderated heavy-tail behavior. In particular, the truncated power law is superior to all competing distributions, or superior to some and as good as the rest, in 99.3% of the cases. These findings have implications that can inform a better modeling of participation in peer production, and help to produce more accurate predictions of the tail behavior, which represents the activity and frequency of the core contributors. Thus, we propose to consider the truncated power law as the distribution to characterize participation distribution in wiki communities. Furthermore, the truncated power law parameters provide a meaningful interpretation to characterize the community in terms of the frequency of participation of occasional contributors and how unequal are the group of core contributors. Finally, we found a relationship between the parameters and the productivity of the community and its size. These results open research venues for the characterization of communities in wikis and in online peer production.
ABSTRACT
Living cells exposed to stressful environmental situations can elicit cellular responses that guarantee maximal cell survival. Most of these responses are mediated by mitogen-activated protein kinase (MAPK) cascades, which are highly conserved from yeast to humans. Cell wall damage conditions in the yeast Saccharomyces cerevisiae elicit rescue mechanisms mainly associated with reprogramming specific transcriptional responses via the cell wall integrity (CWI) pathway. Regulation of gene expression by this pathway is coordinated by the MAPK Slt2/Mpk1, mainly via Rlm1 and, to a lesser extent, through SBF (Swi4/Swi6) transcription factors. In this review, we summarize the molecular mechanisms controlling gene expression upon cell wall stress and the role of chromatin structure in these processes. Some of these mechanisms are also discussed in the context of other stresses governed by different yeast MAPK pathways. Slt2 regulates both transcriptional initiation and elongation by interacting with chromatin at the promoter and coding regions of CWI-responsive genes but using different mechanisms for Rlm1- and SBF-dependent genes. Since MAPK pathways are very well conserved in eukaryotic cells and are essential for controlling cellular physiology, improving our knowledge regarding how they regulate gene expression could impact the future identification of novel targets for therapeutic intervention.
Subject(s)
Saccharomyces cerevisiae Proteins , Saccharomyces cerevisiae , Cell Wall/metabolism , Chromatin/genetics , Chromatin/metabolism , Gene Expression , Gene Expression Regulation, Fungal , Mitogen-Activated Protein Kinases/metabolism , Phosphorylation , Saccharomyces cerevisiae/metabolism , Saccharomyces cerevisiae Proteins/genetics , Saccharomyces cerevisiae Proteins/metabolismABSTRACT
In Saccharomyces cerevisiae cAMP regulates different cellular processes through PKA. The specificity of the response of the cAMP-PKA pathway is highly regulated. Here we address the mechanism through which the cAMP-PKA pathway mediates its response to heat shock and thermal adaptation in yeast. PKA holoenzyme is composed of a regulatory subunit dimer (Bcy1) and two catalytic subunits (Tpk1, Tpk2, or Tpk3). PKA subunits are differentially expressed under certain growth conditions. Here we demonstrate the increased abundance and half-life of TPK1 mRNA and the assembly of this mRNA in cytoplasmic foci during heat shock at 37 °C. The resistance of the foci to cycloheximide-induced disassembly along with the polysome profiling analysis suggest that TPK1 mRNA is impaired for entry into translation. TPK1 expression was also evaluated during a recurrent heat shock and thermal adaptation. Tpk1 protein level is significantly increased during the recovery periods. The crosstalk of cAMP-PKA pathway and CWI signalling was also studied. Wsc3 sensor and some components of the CWI pathway are necessary for the TPK1 expression upon heat shock. The assembly in foci upon thermal stress depends on Wsc3. Tpk1 expression is lower in a wsc3∆ mutant than in WT strain during thermal adaptation and thus the PKA levels are also lower. An increase in Tpk1 abundance in the PKA holoenzyme in response to heat shock is presented, suggesting that a recurrent stress enhanced the fitness for the coming favourable conditions. Therefore, the regulation of TPK1 expression by thermal stress contributes to the specificity of cAMP-PKA signalling.
Subject(s)
Cyclic AMP-Dependent Protein Kinases/metabolism , Saccharomyces cerevisiae Proteins/metabolism , Saccharomyces cerevisiae/metabolism , Cyclic AMP-Dependent Protein Kinases/genetics , Half-Life , Intracellular Signaling Peptides and Proteins/metabolism , Membrane Proteins/metabolism , Polyribosomes/metabolism , Protein Isoforms/genetics , Protein Isoforms/metabolism , Protein Subunits/genetics , Protein Subunits/metabolism , RNA, Messenger/metabolism , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae Proteins/genetics , TemperatureABSTRACT
In this study, we describe SARS-CoV-2 infection dynamics in one cat and three dogs from households with confirmed human cases of COVID-19 living in the Madrid Community (Spain) at the time of expansion (December 2020 through June 2021) of the alpha variant (lineage B.1.1.7). A thorough physical exam and nasopharyngeal, oropharyngeal, and rectal swabs were collected for real-time reverse-transcription PCR (RT-qPCR) SARS-CoV-2 testing on day 0 and in successive samplings on days 7, 14, 21, and 47 during monitoring. Blood was also drawn to determine complete blood counts, biochemical profiles, and serology of the IgG response against SARS-CoV-2. On day 0, the cat case 1 presented with dyspnea and fever associated with a mild bronchoalveolar pattern. The dog cases 2, 3, and 4 were healthy, but case 2 presented with coughing, dyspnea, and weakness, and case 4 exhibited coughing and bilateral nasal discharge 3 and 6 days before the clinical exam. Case 3 (from the same household as case 2) remained asymptomatic. SARS-CoV-2 detection by RT-qPCR showed that the cat case 1 and the dog case 2 exhibited the lowest cycle threshold (Ct) (Ct < 30) when they presented clinical signs. Viral detection failed in successive samplings. Serological analyses revealed a positive IgG response in cat case 1 and dog cases 3 and 4 shortly after or simultaneously to virus shedding. Dog case 2 was seronegative, but seroconverted 21 days after SARS-CoV-2 detection. SARS-CoV-2 genome sequencing was attempted, and genomes were classified as belonging to the B.1.1.7 lineage.
ABSTRACT
As a result of the relatively few available antifungals and the increasing frequency of resistance to them, the development of novel antifungals is increasingly important. The plant natural product poacic acid (PA) inhibits ß-1,3-glucan synthesis in Saccharomyces cerevisiae and has antifungal activity against a wide range of plant pathogens. However, the mode of action of PA is unclear. Here, we reveal that PA specifically binds to ß-1,3-glucan, its affinity for which is ~30-fold that for chitin. Besides its effect on ß-1,3-glucan synthase activity, PA inhibited the yeast glucan-elongating activity of Gas1 and Gas2 and the chitin-glucan transglycosylase activity of Crh1. Regarding the cellular response to PA, transcriptional co-regulation was mediated by parallel activation of the cell-wall integrity (CWI) and high-osmolarity glycerol signaling pathways. Despite targeting ß-1,3-glucan remodeling, the transcriptional profiles and regulatory circuits activated by caspofungin, zymolyase, and PA differed, indicating that their effects on CWI have different mechanisms. The effects of PA on the growth of yeast strains indicated that it has a mode of action distinct from that of echinocandins, suggesting it is a unique antifungal agent.
Subject(s)
Antifungal Agents/pharmacology , Cell Wall/drug effects , Coumaric Acids/pharmacology , Glycerol/metabolism , Saccharomyces cerevisiae/drug effects , Stilbenes/pharmacology , Transcription, Genetic/drug effects , beta-Glucans/pharmacology , Caspofungin/pharmacology , Cell Wall/genetics , Cell Wall/metabolism , Chitin/pharmacology , Echinocandins/pharmacology , Fungal Proteins/genetics , Gene Expression Regulation, Fungal/drug effects , Gene Expression Regulation, Fungal/genetics , Osmolar Concentration , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae/metabolism , Signal Transduction/drug effects , Signal Transduction/genetics , Transcription, Genetic/geneticsABSTRACT
The use of metaproteomics for studying the human gut microbiota can shed light on the taxonomic profile and the functional role of the microbial community. Nevertheless, methods for extracting proteins from stool samples continue to evolve, in the pursuit of optimal protocols for moistening and dispersing the stool sample and for disrupting microbial cells, which are two critical steps for ensuring good protein recovery. Here, we evaluated different stool sample processing (SSP) and microbial cell disruption methods (CDMs). The combination of a longer disintegration period of the stool sample in a tube rotator with sonication increased the overall number of identified peptides and proteins. Proteobacteria, Bacteroidetes, Planctomycetes, and Euryarchaeota identification was favored by mechanical cell disruption with glass beads. In contrast, the relative abundance of Firmicutes, Actinobacteria, and Fusobacteria was improved when sonication was performed before bead beating. Tenericutes and Apicomplexa identification was enhanced by moistening the stool samples during processing and by disrupting cells with medium-sized glass beads combined with or without sonication. Human protein identifications were affected by sonication. To test the reproducibility of these gut metaproteomic analyses, we examined samples from six healthy individuals using a protocol that had shown a good taxonomic diversity and identification of proteins from Proteobacteria and humans. We also detected proteins involved in microbial functions relevant to the host and related mostly to specific taxa, such as B12 biosynthesis and short chain fatty acid (SCFA) production carried out mainly by members in the Prevotella genus and the Firmicutes phylum, respectively. The taxonomic and functional profiles obtained with the different protocols described in this work provides the researcher with valuable information when choosing the most adequate protocol for the study of certain pathologies under suspicion of being related to a specific taxon from the gut microbiota.
ABSTRACT
The aim of our study was to evaluate the diagnostic performance of two antigen rapid diagnostic tests (Ag-RDTs) to diagnose severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. We evaluated Panbio and SD-Biosensor Ag-RDTs. We employed 186 polymerase chain reaction (PCR) negative samples to evaluate the specificity and 170 PCR positive samples to assess the sensitivity. We evaluated their sensitivity according to Cycle threshold (C t ) values and days post onset of symptoms (d.p.o.). Tests were compared using the McNemar's test. Agreement was evaluated using the kappa score. Specificity was 100% for Panbio and 97.3% for SD-Biosensor. Sensitivity for samples with C t ≤ 20 was 100% for both assays and for samples with C t = 20-25 was 93.0% (Panbio) and 95.3% (SD-Biosensor) (p = 1.000). Sensitivity decreased for samples wit C t = 25-30 (Panbio: 41.3%, SD-Biosensor: 52.2%, p = 0.125) and samples with C t ≥ 30 (Panbio: 5.0%, SD-Biosensor: 17.5%, p = 0.063). Sensitivity within seven d.p.o. was 87.7% for Panbio and 90.4% for SD-Biosensor and notably decreased after seven d.p.o. Agreement with PCR was excellent for high viral load samples (C t ≤ 25): Panbio, 98.9%, kappa = 0.974; SD-Biosensor, 97.4%, kappa = 0.940. Agreement between Ag-RDTs was excellent (94.9%, kappa = 0.882). Panbio and SD-Biosensor Ag-RDTs showed excellent agreement and diagnostic performance results for samples with high viral loads (C t ≤ 25) or samples within seven d.p.o.
Subject(s)
COVID-19 Testing/methods , COVID-19/diagnosis , SARS-CoV-2/isolation & purification , Antigens, Viral/analysis , Biosensing Techniques , Diagnostic Tests, Routine , Humans , Nasopharynx/virology , Sensitivity and Specificity , Viral LoadABSTRACT
BACKGROUND: The association between myocardial parasitic load (MPL) and cardiac biomarkers in Canine Leishmaniasis (CanL) has not been studied. METHODS: Dogs with advanced CanL were prospectively recruited and were included if they were euthanised. Prior to euthanasia these variables were assessed: hematocrit, globulin, creatinine, N-terminal-pro brain natriuretic peptide (NT-proBNP), cardiac troponin I (cTnI), blood pressure, urine protein/creatinine ratio and echocardiographic parameters. A left ventricular (LV) sample was taken for histopathology and MPL evaluation by quantitative PCR. Correlation of MPL with all variables was analysed. Dogs with lower and higher histopathology scores were compared. RESULTS: Ten dogs were included. NT-proBNP was 6946 pmol/ (interquartile range [IQR] 3751-9268 pmol/L) and cTnI 4.56 ng/mL (IQR 0.46-13.1 ng/mL). In all dogs, echocardiography showed an increase in LV thickening, and histopathology revealed moderate to severe lympho-plasmocytic myocarditis and/or myocardial cell degeneration. MPL was 215.53 parasites/gram (IQR 21.2-1372.63 parasites/gram). A strong correlation (p < 0.001; R = 0.90; R2 0.81) with cTnI was observed but correlation with any of the other variables or differences between the two histopathological scores, were not detected. CONCLUSIONS: MPL in dogs with advanced CanL shows variable but generally high levels. A strong association between MPL and cTnI was observed, which encourages the exploration of cTnI as a marker in CanL.
Subject(s)
Dog Diseases , Leishmaniasis , Animals , Biomarkers , Dog Diseases/parasitology , Dogs , Leishmaniasis/veterinary , Parasite Load/veterinary , Troponin IABSTRACT
Crh proteins catalyze crosslinking of chitin and glucan polymers in fungal cell walls. Here, we show that the BcCrh1 protein from the phytopathogenic fungus Botrytis cinerea acts as a cytoplasmic effector and elicitor of plant defense. BcCrh1 is localized in vacuoles and the endoplasmic reticulum during saprophytic growth. However, upon plant infection, the protein accumulates in infection cushions; it is then secreted to the apoplast and translocated into plant cells, where it induces cell death and defense responses. Two regions of 53 and 35 amino acids are sufficient for protein uptake and cell death induction, respectively. BcCrh1 mutant variants that are unable to dimerize lack transglycosylation activity, but are still able to induce plant cell death. Furthermore, Arabidopsis lines expressing the bccrh1 gene exhibit reduced sensitivity to B. cinerea, suggesting a potential use of the BcCrh1 protein in plant immunization against this necrotrophic pathogen.
Subject(s)
Arabidopsis/immunology , Arabidopsis/microbiology , Botrytis/enzymology , Cytoplasm/metabolism , Fungal Proteins/metabolism , Glycosyltransferases/metabolism , Plant Cells/microbiology , Agrobacterium/metabolism , Botrytis/growth & development , Botrytis/pathogenicity , Cell Death , Disease Resistance , Fungal Proteins/chemistry , Plant Diseases/microbiology , Plant Immunity , Protein Multimerization , Reactive Oxygen Species/metabolism , Nicotiana/microbiologyABSTRACT
Iron is an essential element for life. Cells develop mechanisms to tightly regulate its homeostasis, in order to avoid abnormal accumulation and the consequent cell toxicity. In budding yeast, the high affinity iron regulon is under the control of the transcription factor Aft1. We present evidence demonstrating that the MAPK Slt2 of the cell wall integrity pathway (CWI), phosphorylates and negatively regulates Aft1 activity upon the iron depletion signal, both in fermentative or respiratory conditions. The lack of Slt2 provokes Aft1 dysfunction leading to a shorter chronological life span. The signal of iron scarcity is not transmitted to Slt2 through other signalling pathways such as TOR1, PKA, SNF1 or TOR2/YPK1. The observation that Slt2 physically binds Aft1 rather suggests a direct regulation.
Subject(s)
Iron/metabolism , Mitogen-Activated Protein Kinases/metabolism , Saccharomyces cerevisiae Proteins/metabolism , Saccharomyces cerevisiae/growth & development , Transcription Factors/metabolism , Fermentation , Gene Expression Regulation, Fungal , Homeostasis , Phosphorylation , Protein Stability , Saccharomyces cerevisiae/metabolism , Saccharomyces cerevisiae Proteins/chemistry , Signal Transduction , Transcription Factors/chemistryABSTRACT
Arterial pseudoaneurysm formation after transradial cardiac catheterization is a rare post-procedural complication occurring in less than 0.1% of radial arterial access. While the data on the management of femoral pseudoaneurysms is extensive, few studies have evaluated how these techniques apply for small vessel arterial pseudoaneurysms. We present the case of an octogenarian man with a radial artery pseudoaneurysm after transradial coronary intervention that failed initial compression therapy, and surgical intervention was avoided by applying continuous compression therapy with a TR Band® radial compression device.
Subject(s)
Aneurysm, False , Catheterization, Peripheral , Aged, 80 and over , Aneurysm, False/diagnostic imaging , Aneurysm, False/etiology , Aneurysm, False/therapy , Cardiac Catheterization/adverse effects , Catheterization, Peripheral/adverse effects , Hemostatic Techniques , Humans , Male , Radial Artery/diagnostic imaging , Radial Artery/surgery , Treatment OutcomeABSTRACT
OBJECTIVE: To analyze the impact of the coronavirus disease 2019 (COVID-19) pandemic in workers of a hospital located in one of the most affected areas in Spain. DESIGN, SETTINGS, AND PATIENTS: Cross-sectional study performed between March and May 2020 over all workers of a secondary hospital in Madrid, Spain. METHODS: We employed polymerase chain reaction (PCR, for symptomatic individuals) and serology (for both PCR-negative symptomatic workers and asymptomatic workers) as diagnostic tests for severe acute respiratory coronavirus virus 2 (SARS-CoV-2). We analyzed the prevalence of the virus in healthcare workers (HCWs) and nonhealthcare workers (nHCWs). We also collected information about the use of personal protective equipment (PPEs) and possible contacts prior to infection. RESULTS: In total, 2,963 workers were included: 1,092 were symptomatic, and of these, 539 were positive by PCR (49.4% of symptomatic workers). From the remaining symptomatic workers, 197 (35.6%) were positive by serology. Regarding asymptomatic workers, 345 were positive by serology (31.9% of infected workers). In total, 1,081 (36.5%) presented a positive diagnostic test for SARS-CoV-2. Infection rates were different between HCWs (37.4%) and nHCWs (29.8%) (P = .006). In the multivariate logistic regression analysis, the use of PPE (protective: OR, 0.56; 95% CI, 0.44-0.72; P < .001) and previous contact with COVID-19 patients (risk factor: OR, 1.69; 95% CI, 1.28-2.24; P < .001) were independent factors that were associated with SAS-CoV-2 infection. CONCLUSIONS: Overall, >36% of our workers became infected with SARS-CoV-2, and the rate of asymptomatic infections accounted for almost 32% of all SARS-CoV-2 infections. We detected differences in the rates of infection between HCWs and nHCWs. The use of PPE and previous contact with COVID-19 patients were associated with SARS-CoV-2 infection.
Subject(s)
COVID-19 , Cross-Sectional Studies , Health Personnel , Hospitals , Humans , Personnel, Hospital , SARS-CoV-2 , Spain/epidemiologyABSTRACT
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
ABSTRACT
N-terminal proB-type natriuretic peptide (NT-proBNP) may be a useful marker in canine leishmaniosis (CanL). The aim was to compare NT-proBNP in dogs at different LeishVet stages of CanL and with idiopathic chronic kidney disease (CKD). Dogs diagnosed with CanL or CKD and a group of healthy dogs were included (group A, five normal dogs; group B, six dogs LeishVet 1-2; group C, 13 dogs LeishVet 3-4; group D, six dogs with CKD). NT-proBNP was higher (P<0.001) in group C (7.616 pmol/l, interquartile range (IQR) 3537-10,000 pmol/l) than in group A (293 pmol/l, IQR 257-373), group B (388.5 pmol/l, IQR 324-793) and group D (740 pmol/l, IQR 557-962 pmol/l). International Renal Interest Society (IRIS) kidney stage was not different between groups C and D or between groups A and B, but was different within all the rest of the group comparisons (P<0.001). In group C all dogs had echocardiographic increase in left ventricular mass index. NT-proBNP had negative correlation with haematocrit (P<0.001, r=0.749) and positive correlation with systemic blood pressure (P<0.001, r=0.728). NT-proBNP is consistently elevated in dogs with advanced CanL and is strongly correlated with the degree of systemic hypertension and anaemia. Moreover, dogs with advanced CanL exhibit increase in left ventricular mass. NT-proBNP may however be a less desirable cardiac marker as unlike cardiac troponin I it is often not elevated at earlier stages of CanL.
Subject(s)
Dog Diseases/blood , Leishmaniasis, Visceral/veterinary , Natriuretic Peptide, Brain/blood , Peptide Fragments/blood , Renal Insufficiency, Chronic/veterinary , Animals , Biomarkers/blood , Dogs , Female , Humans , Leishmaniasis, Visceral/blood , Male , Renal Insufficiency, Chronic/bloodABSTRACT
Fungal cell wall synthesis is achieved by a balance of glycosyltransferase, hydrolase and transglycosylase activities. Transglycosylases strengthen the cell wall by forming a rigid network of crosslinks through mechanisms that remain to be explored. Here we study the function of the Aspergillus fumigatus family of five Crh transglycosylases. Although crh genes are dispensable for cell viability, simultaneous deletion of all genes renders cells sensitive to cell wall interfering compounds. In vitro biochemical assays and localisation studies demonstrate that this family of enzymes functions redundantly as transglycosylases for both chitin-glucan and chitin-chitin cell wall crosslinks. To understand the molecular basis of this acceptor promiscuity, we solved the crystal structure of A. fumigatus Crh5 (AfCrh5) in complex with a chitooligosaccharide at the resolution of 2.8 Å, revealing an extensive elongated binding cleft for the donor (-4 to -1) substrate and a short acceptor (+1 to +2) binding site. Together with mutagenesis, the structure suggests a "hydrolysis product assisted" molecular mechanism favouring transglycosylation over hydrolysis.
Subject(s)
Aspergillus fumigatus/metabolism , Fungal Proteins/metabolism , Glycosyltransferases/metabolism , Binding Sites/genetics , Cell Wall/metabolism , Chitin/metabolism , Crystallography, X-Ray , Fungal Proteins/chemistry , Fungal Proteins/genetics , Gene Knockdown Techniques , Glycosyltransferases/chemistry , Glycosyltransferases/genetics , Mutagenesis, Site-Directed , Protein Domains/genetics , Substrate Specificity , beta-Glucans/metabolismABSTRACT
Aspergillus fumigatus is an airborne opportunistic fungal pathogen responsible for severe infections. Among them, invasive pulmonary aspergillosis has become a major concern as mortality rates exceed 50% in immunocompromised hosts. In parallel, allergic bronchopulmonary aspergillosis frequently encountered in cystic fibrosis patients, is also a comorbidity factor. Current treatments suffer from high toxicity which prevents their use in weakened subjects, resulting in impaired prognostic. Because of their low toxicity and high specificity, anti-infectious therapeutic antibodies could be a new alternative to conventional therapeutics. In this study, we investigated the potential of Chitin Ring Formation cell wall transglycosylases of A. fumigatus to be therapeutic targets for therapeutic antibodies. We demonstrated that the Crf target was highly conserved, regardless of the pathophysiological context; whereas the CRF1 gene was found to be 100% conserved in 92% of the isolates studied, Crf proteins were expressed in 98% of the strains. In addition, we highlighted the role of Crf proteins in fungal growth, using a deletion mutant for CRF1 gene, for which a growth decrease of 23.6% was observed after 48 h. It was demonstrated that anti-Crf antibodies neutralized the enzymatic activity of recombinant Crf protein, and delayed fungal growth by 12.3% in vitro when added to spores. In a neutropenic rat model of invasive pulmonary aspergillosis, anti-Crf antibodies elicited a significant recruitment of neutrophils, macrophages and T CD4 lymphocytes but it was not correlated with a decrease of fungal burden in lungs and improvement in survival. Overall, our study highlighted the potential relevance of targeting Crf cell wall protein (CWP) with therapeutic antibodies.