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BACKGROUND & AIMS: Cholangiocarcinoma (CCA) is a cancer of the hepatic bile ducts that is rarely resectable and is associated with poor prognosis. Tumour necrosis factor-like weak inducer of apoptosis (TWEAK) is known to signal via its receptor fibroblast growth factor-inducible 14 (Fn14) and induce cholangiocyte and myofibroblast proliferation in liver injury. We aimed to characterise its role in CCA. METHODS: The expression of the TWEAK ligand and Fn14 receptor was assessed immunohistochemically and by bulk RNA and single cell transcriptomics of human liver tissue. Spatiotemporal dynamics of pathway regulation were comprehensively analysed in rat and mouse models of thioacetamide (TAA)-mediated CCA. Flow cytometry, qPCR and proteomic analyses of CCA cell lines and conditioned medium experiments with primary macrophages were performed to evaluate the downstream functions of TWEAK/Fn14. In vivo pathway manipulation was assessed via TWEAK overexpression in NICD/AKT-induced CCA or genetic Fn14 knockout during TAA-mediated carcinogenesis. RESULTS: Our data reveal TWEAK and Fn14 overexpression in multiple human CCA cohorts, and Fn14 upregulation in early TAA-induced carcinogenesis. TWEAK regulated the secretion of factors from CC-SW-1 and SNU-1079 CCA cells, inducing polarisation of proinflammatory CD206+ macrophages. Pharmacological blocking of the TWEAK downstream target chemokine monocyte chemoattractant protein 1 (MCP-1 or CCL2) significantly reduced CCA xenograft growth, while TWEAK overexpression drove cancer-associated fibroblast proliferation and collagen deposition in the tumour niche. Genetic Fn14 ablation significantly reduced inflammatory, fibrogenic and ductular responses during carcinogenic TAA-mediated injury. CONCLUSION: These novel data provide evidence for the action of TWEAK/Fn14 on macrophage recruitment and phenotype, and cancer-associated fibroblast proliferation in CCA. Targeting TWEAK/Fn14 and its downstream signals may provide a means to inhibit CCA niche development and tumour growth. LAY SUMMARY: Cholangiocarcinoma is an aggressive, chemotherapy-resistant liver cancer. Interactions between tumour cells and cells that form a supportive environment for the tumour to grow are a source of this aggressiveness and resistance to chemotherapy. Herein, we describe interactions between tumour cells and their supportive environment via a chemical messenger, TWEAK and its receptor Fn14. TWEAK/Fn14 alters the recruitment and type of immune cells in tumours, increases the growth of cancer-associated fibroblasts in the tumour environment, and is a potential target to reduce tumour formation.
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Neoplasias dos Ductos Biliares , Quimiocina CCL2/metabolismo , Colangiocarcinoma , Citocina TWEAK/metabolismo , Fatores de Crescimento de Fibroblastos/metabolismo , Animais , Neoplasias dos Ductos Biliares/metabolismo , Neoplasias dos Ductos Biliares/patologia , Carcinogênese/metabolismo , Linhagem Celular Tumoral , Proliferação de Células , Colangiocarcinoma/metabolismo , Colangiocarcinoma/patologia , Descoberta de Drogas , Humanos , Camundongos , Ratos , Transdução de Sinais , Microambiente Tumoral , Fator de Necrose Tumoral alfa/metabolismo , Regulação para CimaRESUMO
The growing worldwide challenge of cirrhosis and hepatocellular carcinoma due to increasing prevalence of excessive alcohol consumption, viral hepatitis, obesity, and the metabolic syndrome has sparked interest in stem cell-like liver progenitor cells (LPCs) as potential candidates for cell therapy and tissue engineering, as an alternative approach to whole organ transplantation. However, LPCs always proliferate in chronic liver diseases with a predisposition to cancer; they have been suggested to play major roles in driving fibrosis, disease progression, and may even represent tumor-initiating cells. Hence, a greater understanding of the factors that govern their activation, communication with other hepatic cell types, and bipotential differentiation as opposed to their potential transformation is needed before their therapeutic potential can be harnessed.
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Carcinogênese/patologia , Cirrose Hepática/patologia , Neoplasias Hepáticas/patologia , Regeneração Hepática , Fígado/patologia , Células-Tronco , Animais , HumanosRESUMO
This study was undertaken to compare the immunogenicity and protective potential of biofilm vs planktonic Staphylococcus aureus vaccine for the prevention of mastitis using the mouse as a model system. Mice immunized with formalin-killed whole cell vaccine of S. aureus residing in a biofilm when delivered via an intramammary route produced a cell mediated immune response. Mice immunized with this biofilm vaccine showed significant reductions in colonization by S. aureus in mammary glands, severity of clinical symptoms and tissue damage in mammary glands in comparison with the mice immunized with formalin-killed whole cells of planktonic S. aureus. The planktonic vaccine administered by a subcutaneous route produced a significantly higher humoral immune response (IgG1 and IgG) than the biofilm vaccine. However, considering the host response, tissue damage, the clinical severity and colonization of S. aureus in mammary glands, the biofilm vaccine performed better in immunogenicity and protective potential when administered by the intramammary route.
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Biofilmes/efeitos dos fármacos , Mastite Bovina , Plâncton/microbiologia , Infecções Estafilocócicas , Vacinas Antiestafilocócicas/farmacologia , Staphylococcus aureus/imunologia , Animais , Bovinos , Feminino , Humanos , Imunoglobulina G/análise , Mastite Bovina/imunologia , Mastite Bovina/microbiologia , Mastite Bovina/prevenção & controle , Camundongos , Modelos Animais , Infecções Estafilocócicas/imunologia , Infecções Estafilocócicas/prevenção & controleRESUMO
The development of persistent antibiotic resistance by human methicillin-sensitive Staphylococcus aureus (MSSA) strains and substantial association with poly-N-acetyl glucosamine (PNAG) in biofilms is reported in this investigation. Sixteen of 31 MSSA strains under study were found to have developed resistance to one or more antibiotics, with four strains, two of which did not produce biofilms, showing resistance to cefoxitin, undetectable by mecA amplification. Antibiotic resistance displayed by 13/14 biofilm-forming S. aureus isolates remained persistent for 4 weeks prior to reverting back to the original antibiotic susceptibility, prompting a suggestion of determining antibiograms for clinical S. aureus isolates subcultured from biofilms developed in vitro as well as planktonic subcultures prepared from the site of infection. While there was correlation of antibiotic resistance with biofilm formation confirming previous reports, this is the first time that persistence of the biofilm-associated antibiotic resistance by S. aureus as planktonic cells is reported. Among the two methods used for assessment of biofilm formation, the tissue culture plate (TCP) method revealed that almost all strains were strong or moderate biofilm producers whereas only 19/31 strains were biofilm producers using the Congo Red agar (CRA) method indicating the superiority of the TCP method in detecting biofilm producers. We also observed no association between biofilm formation and major capsule types. However, substantial, although not absolute, association of biofilm formation with PNAG was observed, warranting continued identification of additional surface-associated polysaccharide and/or protein antigens associated with biofilm formation for development of an effective vaccine against S. aureus infections regardless of capsular phenotype.
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Acetilglucosamina/biossíntese , Antibacterianos/farmacologia , Biofilmes/crescimento & desenvolvimento , Cefoxitina/farmacologia , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Aderência Bacteriana/efeitos dos fármacos , Cápsulas Bacterianas/química , Cápsulas Bacterianas/efeitos dos fármacos , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Biofilmes/efeitos dos fármacos , Farmacorresistência Bacteriana , Expressão Gênica , Humanos , Staphylococcus aureus Resistente à Meticilina/genética , Staphylococcus aureus Resistente à Meticilina/crescimento & desenvolvimento , Staphylococcus aureus Resistente à Meticilina/isolamento & purificação , Testes de Sensibilidade Microbiana , Proteínas de Ligação às Penicilinas , Plâncton/efeitos dos fármacos , Infecções Estafilocócicas/microbiologiaRESUMO
Chronic pancreatitis increases the risk of developing pancreatic cancer through the upregulation of pathways favouring proliferation, fibrosis, and sustained inflammation. We established in previous studies that the ligand tumour necrosis factor (TNF)-like weak inducer of apoptosis (TWEAK) signals through its cognate receptor fibroblast growth factor-inducible 14 (Fn14) to regulate these underlying cellular processes in the chronic liver injury niche. However, the role of the TWEAK/Fn14 signalling pathway in pancreatic disease is entirely unknown. An analysis of publicly available datasets demonstrated that the TWEAK receptor Fn14 is upregulated in pancreatitis and pancreatic adenocarcinoma, with single cell RNA sequencing revealing pancreatic ductal cells as the main Fn14 producers. We then used choline-deficient, ethionine-supplemented (CDE) diet feeding of wildtype C57BL/6J and Fn14 knockout littermates to (a) confirm CDE treatment as a suitable model of chronic pancreatitis and (b) to investigate the role of the TWEAK/Fn14 signalling pathway in pancreatic ductal proliferation, as well as fibrotic and inflammatory cell dynamics. Our time course data obtained at three days, three months, and six months of CDE treatment reveal that a lack of TWEAK/Fn14 signalling significantly inhibits the establishment and progression of the tissue microenvironment in CDE-induced chronic pancreatitis, thus proposing the TWEAK/Fn14 pathway as a novel therapeutic target.
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Mycoplasma bovis (M. bovis) can cause a multitude of diseases in cattle, with detrimental effects on the farm economy and the welfare of both adult and young cattle. The objective of this study was to determine the prevalence of M. bovis in adult cows and calves in the south-west region of Western Australia. A cross-sectional study was conducted on 29 dairy farms with 699 apparently healthy adult lactating cows and 495 young calves during 2019-2020. Nasal swabs and blood samples collected from the animals and bulk tank milk (BTM) samples were assessed for M. bovis-specific proteins and antibodies by using polymerase chain reaction (PCR) and Mycoplasma immunogenic lipase A- Enzyme-Linked Immune Sorbent Assay (MilA ELISA). A seroprevalence of 42.5% (95% CI: 38.9-46.2) and 61% (95% CI: 56.6-65.2) was found in adult lactating cows and calves, respectively. The herd-level seroprevalence of M. bovis ranged from 4% (95% CI: 07-19.5) to 92% (95% CI: 75.0-97.8) in adult lactating cows and 25% (95% CI: 10.2-49.5) to 87% (95% CI: 67.9-95.5) for calves in these farms. None of the BTM and nasal swab samples were positive for M. bovis, indicating an absence of any current active infections on the farms. The female calves and pure Holstein-Friesian animals are twice as likely to be seropositive for M. bovis compared to male calves (OR 2.4; 95% CI: 1.7-3.5) and Holstein-Friesian crossbred calves (OR 2.4; 95% CI: 1.7-3.5). The high seroprevalence in both adult and young cattle in the southwest dairy farms of Western Australia warrants more effective farm biosecurity measures and further evaluation of the current prevention and management measures practiced on the farms.
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Non-typeable (NT) Staphylococcus aureus strains are associated with chronic bovine mastitis. This study investigates the impact of biofilm formation by clinical NT S. aureus on cytokine production and mammary tissue damage by using a mouse mastitis model. Mice infected with two different NT S. aureus strains with strong and weak biofilm forming potential demonstrated identical clinical symptoms (moderate), minimal inflammatory infiltrates, and tissue damage (level 1 histopathological changes) in the mammary glands. However, the S. aureus load in the mammary glands of mice and the level of pro-inflammatory cytokines (IL-1ß, IL-6, IL-12, IL-17 and IFN-γ) in serum were significantly higher (p ≤ 0.05) in those infected with the strong biofilm forming NT S. aureus strain. The level of IL-6 in sera samples of these mice was extremely high (15,479.9 ± 532 Pg/mL). Furthermore, these mice died in 24h of post infection compared to 30 h in the weak biofilm forming NT S. aureus infected group. The study demonstrates no association between the strength of PIA (polysaccharide intercellular adhesion)-dependent biofilm production by clinical NT S. aureus and mammary gland pathology in a mouse mastitis model. However, the role of biofilm in the virulence of S. aureus advancing the time of mortality in mice warrants further investigation.
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Chronic liver injury is characterised by continuous or repeated epithelial cell loss and inflammation. Hepatic wound healing involves matrix deposition through activated hepatic stellate cells (HSCs) and the expansion of closely associated Ductular Reactions and liver progenitor cells (LPCs), which are thought to give rise to new epithelial cells. In this study, we used the murine thioacetamide (TAA) model to reliably mimic these injury and regeneration dynamics and assess the impact of a recovery phase on subsequent liver injury and fibrosis. Age-matched naïve or 6-week TAA-treated/4-week recovered mice (C57BL/6 J, n = 5-9) were administered TAA for six weeks (C57BL/6 J, n = 5-9). Sera and liver tissues were harvested at key time points to assess liver injury biochemically, by real-time PCR for fibrotic mediators, Sirius Red staining and hydroxyproline assessment for collagen deposition as well as immunofluorescence for inflammatory, HSC and LPC markers. In addition, primary HSCs and the HSC cell line LX-2 were co-cultured with the well-characterised LPC line BMOL and analysed for potential changes in expression of fibrogenic mediators. Our data demonstrate that recovery from a previous TAA insult, with LPCs still present on day 0 of the second treatment, led to a reduced TAA-induced disease progression with less severe fibrosis than in naïve TAA-treated animals. Importantly, primary activated HSCs significantly reduced pro-fibrogenic gene expression when co-cultured with LPCs. Taken together, previous TAA injury established a fibro-protective molecular and cellular microenvironment. Our proof-of principle HSC/LPC co-culture data demonstrate that LPCs communicate with HSCs to regulate fibrogenesis, highlighting a key role for LPCs as regulatory cells during chronic liver disease.
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Doença Hepática Induzida por Substâncias e Drogas/patologia , Células Estreladas do Fígado/citologia , Cirrose Hepática/patologia , Regeneração Hepática/fisiologia , Fígado/citologia , Células-Tronco/citologia , Tioacetamida/toxicidade , Animais , Células Cultivadas , Doença Hepática Induzida por Substâncias e Drogas/etiologia , Doença Hepática Induzida por Substâncias e Drogas/metabolismo , Técnicas de Cocultura , Modelos Animais de Doenças , Células Estreladas do Fígado/metabolismo , Fígado/metabolismo , Cirrose Hepática/etiologia , Cirrose Hepática/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Células-Tronco/metabolismoRESUMO
A cost-effective estimation of the number of free-roaming dogs is an essential prerequisite for the control of rabies in countries where the disease is endemic, as vaccination of at least 70% of the population is recommended to effectively control the disease. Although estimating the population size through sight-resight based maximum likelihood methodology generates an estimate closest to the actual size, it requires at least five survey efforts to achieve this. In a rural setting in India, a reliable estimate of at least 70% of the likely true population of free-roaming dogs was obtained with the Application SuperDuplicates shinyapp online tool using a photographic sight-resight technique through just two surveys. We tested the wider applicability of this method by validating its use in urban settings in India. Sight-resight surveys of free-roaming dogs were conducted in 15 sectors of the Panchkula Municipal Corporation in north India during September- October 2016. A total of 1,408 unique dogs were identified through 3,465 sightings on 14 survey tracks. The estimates obtained by the Application SuperDuplicates shinyapp online tool after two surveys were compared with the maximum likelihood estimates and it was found that the former, after two surveys, provided an estimate that was at least 70% of that obtained by the latter after 5-6 surveys. Thus, the Application SuperDuplicates shinyapp online tool provides an efficient means for estimating the minimum number of free-roaming dogs to vaccinate with a considerably lower effort than the traditional mark-resight based methods. We recommend use of this tool for estimating the vaccination target of free-roaming dogs prior to undertaking mass vaccination efforts against rabies.
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The concentration of Terramycin and Furazolidone residues in broiler meat following their subtherapeutic use in the ration of the birds were detected as 296 ng/g, 174 ng/g, 40 ng/g, 60 ng/g and 124 ng/ml in kidney, liver, thigh muscle, breast muscle and serum for Terramycin and 270 ng/g 160 ng/g and 88 ng/ml in kidney, liver and serum for Furazolidone. One week of withdrawal period from the antibiotic in feed/water was sufficient to render the meat free from residues.
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Ração Animal/efeitos adversos , Contaminação de Alimentos/análise , Furazolidona , Oxitetraciclina/análise , Aves Domésticas , Animais , Resíduos de Drogas/análise , Humanos , ÍndiaRESUMO
The presence of unvaccinated free-roaming dogs (FRD) amidst human settlements is a major contributor to the high incidence of rabies in countries such as India, where the disease is endemic. Estimating FRD population size is crucial to the planning and evaluation of interventions, such as mass immunisation against rabies. Enumeration techniques for FRD are resource intensive and can vary from simple direct counts to statistically complex capture-recapture techniques primarily developed for ecological studies. In this study we compared eight capture-recapture enumeration methods (Lincoln-Petersen's index, Chapman's correction estimate, Beck's method, Schumacher-Eschmeyer method, Regression method, Mark-resight logit normal method, Huggin's closed capture models and Application SuperDuplicates on-line tool) using direct count data collected from Shirsuphal village of Baramati town in Western India, to recommend a method which yields a reasonably accurate count to use for effective vaccination coverage against rabies with minimal resource inputs. A total of 263 unique dogs were sighted at least once over 6 observation occasions with no new dogs sighted on the 7th occasion. Besides this direct count, the methods that do not account for individual heterogeneity yielded population estimates in the range of 248-270, which likely underestimate the real FRD population size. Higher estimates were obtained using the Huggin's Mh-Jackknife (437 ± 33), Huggin's Mth-Chao (391 ± 26), Huggin's Mh-Chao (385 ± 30), models and Application "SuperDuplicates" tool (392 ± 20) and were considered more robust. When the sampling effort was reduced to only two surveys, the Application SuperDuplicates online tool gave the closest estimate of 349 ± 36, which is 74% of the estimated highest population of free-roaming dogs in Shirsuphal village. This method may thus be considered the most reliable method for estimating the FRD population with minimal inputs (two surveys conducted on consecutive days).
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OBJECTIVE: To assess if Staphylococcus aureus is transmitted between man and animals & vice-versa. METHODS: Staphylococcus aureus belonging to biotype C (bovine origin) were isolated from nares and hands of workers on six dairy farms of Assam and Meghalaya. The cows on the farms had a high rate of prevalence of mastitis caused by the same biotype of S. aureus. Three strains of S. aureus biotype A (human origin) were isolated from mastitis milk samples from cows on one of these farms, in which one of the workers was having cuteneous lesions (crusty abscess) and one strain of S. aureus biotype A was isolated from a swab sample collected from an abscess on the skin of the worker. RESULTS: It has been revealed that all the members of the workers family were suffering from a similar type of cuteneous infection, indicating that it was a case of impetigo. The antibiotic susceptibility pattern of all the three biotype A strains from bovine origin was identical to that of the biotype A strains isolated from the worker. The percentage of resistance to 12 commonly used therapeutic antimicrobial agents was higher among the biotype C strains from human origin than the biotype C strains from bovine origin. Several strains from cattle and human origins showed identical antimicrobial susceptibility patterns against the tested agents.
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Doenças dos Bovinos/transmissão , Indústria de Laticínios , Infecções Estafilocócicas/veterinária , Animais , Antibacterianos/uso terapêutico , Técnicas de Tipagem Bacteriana , Bovinos , Doenças dos Bovinos/epidemiologia , Doenças dos Bovinos/microbiologia , Farmacorresistência Bacteriana Múltipla , Humanos , Índia/epidemiologia , Testes de Sensibilidade Microbiana , Prevalência , Infecções Estafilocócicas/epidemiologia , Infecções Estafilocócicas/transmissão , ZoonosesRESUMO
Staphylococcus aureus in biofilms is highly resistant to the treatment with antibiotics, to which the planktonic cells are susceptible. This is likely to be due to the biofilm creating a protective barrier that prevents antibiotics from accessing the live pathogens buried in the biofilm. S. aureus biofilms consist of an extracellular matrix comprising, but not limited to, extracellular bacterial DNA (eDNA) and poly-ß-1, 6-N-acetyl-d-glucosamine (PNAG). Our study revealed that despite inferiority of dispersin B (an enzyme that degrades PNAG) to DNase I that cleaves eDNA, in dispersing the biofilm of S. aureus, both enzymes were equally efficient in enhancing the antibacterial efficiency of tobramycin, a relatively narrow-spectrum antibiotic against infections caused by gram-positive and gram-negative pathogens, including S. aureus, used in this investigation. However, a combination of these two biofilm-degrading enzymes was found to be significantly less effective in enhancing the antimicrobial efficacy of tobramycin than the individual application of the enzymes. These findings indicate that combinations of different biofilm-degrading enzymes may compromise the antimicrobial efficacy of antibiotics and need to be carefully assessed in vitro before being used for treating medical devices or in pharmaceutical formulations for use in the treatment of chronic ear or respiratory infections.
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Antibacterianos/farmacologia , Proteínas de Bactérias/metabolismo , Biofilmes/efeitos dos fármacos , Desoxirribonuclease I/metabolismo , Staphylococcus aureus/efeitos dos fármacos , Tobramicina/farmacologia , DNA Bacteriano/genética , Testes de Sensibilidade Microbiana/métodos , Staphylococcus aureus/metabolismoRESUMO
BACKGROUND: Biofilm formation by Staphylococcus aureus is an important virulence attribute because of its potential to induce persistent antibiotic resistance, retard phagocytosis and either attenuate or promote inflammation, depending upon the disease syndrome, in vivo. This study was undertaken to evaluate the potential significance of strength of biofilm formation by clinical bovine mastitis-associated S. aureus in mammary tissue damage by using a mouse mastitis model. METHODS: Two S. aureus strains of the same capsular phenotype with different biofilm forming strengths were used to non-invasively infect mammary glands of lactating mice. Biofilm forming potential of these strains were determined by tissue culture plate method, ica typing and virulence gene profile per detection by PCR. Delivery of the infectious dose of S. aureus was directly through the teat lactiferous duct without invasive scraping of the teat surface. Both bacteriological and histological methods were used for analysis of mammary gland pathology of mice post-infection. RESULTS: Histopathological analysis of the infected mammary glands revealed that mice inoculated with the strong biofilm forming S. aureus strain produced marked acute mastitic lesions, showing profuse infiltration predominantly with neutrophils, with evidence of necrosis in the affected mammary glands. In contrast, the damage was significantly less severe in mammary glands of mice infected with the weak biofilm-forming S. aureus strain. Although both IL-1ß and TNF-α inflammatory biomarkers were produced in infected mice, level of TNF-α produced was significantly higher (p<0.05) in mice inoculated with strong biofilm forming S. aureus than the weak biofilm forming strain. CONCLUSION: This finding suggests an important role of TNF-α in mammary gland pathology post-infection with strong biofilm-forming S. aureus in the acute mouse mastitis model, and offers an opportunity for the development of novel strategies for reduction of mammary tissue damage, with or without use of antimicrobials and/or anti-inflammatory compounds for the treatment of bovine mastitis.
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Biofilmes/crescimento & desenvolvimento , Mastite Bovina/microbiologia , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/crescimento & desenvolvimento , Animais , Bovinos , Modelos Animais de Doenças , Feminino , Interleucina-1beta/metabolismo , Glândulas Mamárias Animais/metabolismo , Glândulas Mamárias Animais/microbiologia , Glândulas Mamárias Animais/patologia , Mastite Bovina/metabolismo , Mastite Bovina/patologia , Camundongos , Projetos Piloto , Infecções Estafilocócicas/patologia , Staphylococcus aureus/metabolismo , Staphylococcus aureus/patogenicidade , Fator de Necrose Tumoral alfa/metabolismoRESUMO
Chronic liver diseases, such as viral hepatitis, alcoholic liver disease, or non-alcoholic fatty liver disease, are characterized by continual inflammation, progressive destruction and regeneration of the hepatic parenchyma, liver progenitor cell proliferation, and fibrosis. The end-stage of every chronic liver disease is cirrhosis, a major risk factor for the development of hepatocellular carcinoma. To study processes regulating disease initiation, establishment, and progression, several animal models are used in laboratories. Here we describe a six-week time course of the choline-deficient and ethionine-supplemented (CDE) mouse model, which involves feeding six-week old male C57BL/6J mice with choline-deficient chow and 0.15% DL-ethionine-supplemented drinking water. Monitoring of animal health and a typical body weight loss curve are explained. The protocol demonstrates the gross examination of a CDE-treated liver and blood collection by cardiac puncture for subsequent serum analyses. Next, the liver perfusion technique and collection of different hepatic lobes for standard evaluations are shown, including liver histology assessments by hematoxylin and eosin or Sirius Red stainings, immunofluorescent detection of hepatic cell populations as well as transcriptome profiling of the liver microenvironment. This mouse model is suitable for studying inflammatory, fibrogenic, and liver progenitor cell dynamics induced through chronic liver disease and can be used to test potential therapeutic agents that may modulate these processes.
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Deficiência de Colina/etiologia , Modelos Animais de Doenças , Etionina/administração & dosagem , Lesão Pulmonar/etiologia , Animais , Proliferação de Células/fisiologia , Deficiência de Colina/metabolismo , Dieta , Suplementos Nutricionais , Fígado/patologia , Lesão Pulmonar/metabolismo , Lesão Pulmonar/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BLRESUMO
Attachment of bacterial pathogens to the niche tissue in the host is the first step in biofilm formation leading to colonization and establishment of infection in the host. While the most common method used for determining the potential role of a bacterial antigen in biofilm formation has been demonstration of loss of this property using specific knockout mutants, it is an expensive and a laborious procedure. This study describes an alternative immunological assay for identification of attachment antigens of Staphylococcus aureus, potentially important in the development of an effective vaccine against infections caused by this pathogen. The method is based upon the concept of inhibition of attachment of S. aureus to PEGs coated with virulence antigen-specific antibodies. Antibodies used for validation of this assay were specific for ClfA, FnBPA, SdrD, PNAG and α-toxin, accredited biofilm-associated antigens of S. aureus.
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Antígenos de Bactérias/análise , Biofilmes/crescimento & desenvolvimento , Imunoensaio/métodos , Staphylococcus aureus/química , Staphylococcus aureus/fisiologia , Adesinas Bacterianas/análise , Anticorpos Antibacterianos/metabolismo , Aderência Bacteriana , PoliestirenosRESUMO
Protein A, encoded by the spa gene, is one of the major immune evading MSCRAMM of S. aureus, demonstrated to be prevalent in a significant percentage of clinical bovine mastitis isolates in Australia. Given its' reported significance in biofilm formation and the superior performance of S. aureus biofilm versus planktonic vaccine in the mouse mastitis model, it was of interest to determine the immunogenicity and protective potential of Protein A as a potential vaccine candidate against bovine mastitis using the mouse mastitis model. Pregnant Balb/c mice were immunised with Protein A emulsified in an alum-based adjuvant by subcutaneous (s/c) or intramammary (i/mam) routes. While humoral immune response of mice post-immunization were determined using indirect ELISA, cell-mediated immune response was assessed by estimation of interferon-gamma (IFN-γ) produced by protein A-stimulated splenocyte supernatants. Protective potential of Protein A against experimental mastitis was determined by challenge of immunized versus sham-vaccinated mice by i/mam route, based upon manifestation of clinical symptoms, total bacterial load and histopathological damage to mammary glands. Significantly (p<0.05) higher levels of IgG1 isotype were produced in mice immunized by the s/c route. In contrast, significantly higher levels of the antibody isotype IgG2a were produced in mice immunized by the i/mam route (p<0.05). There was significant reduction (p<0.05) in bacterial loads of the mammary glands of mice immunized by Protein A regardless of the route of immunization, with medium level of clinical symptoms observed up to day 3 post-challenge. However, Protein A vaccine failed to protect immunized mice post-challenge with biofilm producing encapsulated S. aureus via i/mam route, regardless of the route of immunization, as measured by the level of mammary tissue damage. It was concluded that, Protein A in its' native state was apparently not a suitable candidate for inclusion in a cell-free vaccine formulation against mastitis.
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Carga Bacteriana , Vacinas Bacterianas/imunologia , Glândulas Mamárias Animais/imunologia , Glândulas Mamárias Animais/microbiologia , Mastite/imunologia , Proteína Estafilocócica A/imunologia , Animais , Biofilmes , Concanavalina A/química , Ensaio de Imunoadsorção Enzimática , Feminino , Imunização , Imunoglobulina G/imunologia , Injeções Subcutâneas , Interferon gama/metabolismo , Camundongos , Camundongos Endogâmicos BALB C , Gravidez , Baço/citologiaRESUMO
An extensive array of virulence factors associated with S. aureus has contributed significantly to its success as a major nosocomial pathogen in hospitals and community causing variety of infections in affected patients. Virulence factors include immune evading capsular polysaccharides, poly-N-acetyl glucosamine, and teichoic acid in addition to damaging toxins including hemolytic toxins, enterotoxins, cytotoxins, exfoliative toxin, and microbial surface components recognizing adhesive matrix molecules (MSCRAMM). In this investigation, 31 West Australian S. aureus isolates of human origin and 6 controls were analyzed for relative distribution of virulence-associated genes using PCR and/or an immunoassay kit and MSCRAMM by PCR-based typing. Genes encoding MSCRAMM, namely, Spa, ClfA, ClfB, SdrE, SdrD, IsdA, and IsdB, were detected in >90% of isolates. Gene encoding α-toxin was detected in >90% of isolates whereas genes encoding ß-toxin and SEG were detectable in 50-60% of isolates. Genes encoding toxin proteins, namely, SEA, SEB, SEC, SED, SEE, SEH, SEI, SEJ, TSST, PVL, ETA, and ETB, were detectable in >50% of isolates. Use of RAPD-PCR for determining the virulence factor-based genetic relatedness among the isolates revealed five cluster groups confirming genetic diversity among the MSSA isolates, with the greatest majority of the clinical S. aureus (84%) isolates clustering in group IIIa.
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Meticilina/farmacologia , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/genética , Fatores de Virulência/genética , Adesinas Bacterianas/genética , Austrália , Toxinas Bacterianas/genética , DNA Bacteriano/genética , Variação Genética/genética , Proteínas Hemolisinas/genética , Humanos , Esfingomielina Fosfodiesterase/genéticaRESUMO
The aim of this study was to compare the performance of serological versus molecular typing methods to detect capsular polysaccharide (CP) and surface-associated polysaccharide antigen 336 phenotypes of Staphylococcus aureus isolates. Molecular typing of CP types 1, 5 and 8 was carried out using PCR, whereas serological typing of CP1, 2, 5, 8 and antigen 336 was carried out by slide agglutination using specific antisera. By genotyping, 14/31 strains were CP8 positive, 12/31 strains were CP5 and the remaining 6/31 isolates were non-typable (NT). One isolate was positive for both CP5 and CP8 by PCR, but was confirmed as CP8 type serologically. Detection of CP2 and type 336 by PCR was not possible because specific primers were either not available or non-specific. Using serotyping, 14/31 strains were CP8 positive, 11/31 CP5 positive and 2/31 positive for antigen 336. The remaining four S. aureus isolates were serologically NT. However, three of four NT and two 336-positive S. aureus isolates were encapsulated as determined by light microscopy after capsular staining. This discovery was surprising and warrants further investigations on the identification and characterization of additional capsular phenotypes prevalent among S. aureus clinical isolates. It was concluded that serological typing was a better method than molecular typing for use in epidemiological investigations based upon the distribution of surface-associated polysaccharide antigens-based phenotypes.
Assuntos
Tipagem Molecular/métodos , Polissacarídeos Bacterianos/metabolismo , Testes Sorológicos/métodos , Staphylococcus aureus/metabolismo , Genótipo , Humanos , Evasão da Resposta Imune/fisiologia , Polissacarídeos Bacterianos/genética , Polissacarídeos Bacterianos/imunologia , Staphylococcus aureus/genética , Staphylococcus aureus/imunologia , Austrália OcidentalRESUMO
The aim of this investigation was to determine the persistence of biofilm-associated antibiotic resistance developed by methicillin-sensitive Staphylococcus aureus (MSSA), of different capsular types, during biofilm formation. Because of superiority of the tissue culture plate (TCP) over the Congo Red Agar (CRA) method for measuring biofilm formation, it was used to determine the persistence of the antibiotic resistance developed by the isolates in biofilms. The antibiotic resistance was found to persist for 3-4 wk post-propagation as planktonic subcultures. Interestingly, some strains even developed resistance to vancomycin and/or teicoplanin. However, no association of either biofilm formation or persistent antibiotic resistance with the major capsular phenotype was observed. These observations highlight the potential significance of (a) determining the antibiograms of S. aureus subcultured from biofilms developed in vitro using the TCP method as well as from planktonic cultures for formulation of an optimal therapeutic strategy, and (b) continuing to identify predominant non-capsular antigens contributing to biofilm formation, regardless of the capsular phenotype for the development of an effective potentially broad-spectrum vaccine for prevention of bovine mastitis caused by S. aureus.