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Ischemic stroke followed by reperfusion (IR) leads to extensive cerebrovascular injury characterized by neuroinflammation and brain cell death. Inhibition of matrix metalloproteinase-3 (MMP-3) emerges as a promising therapeutic approach to mitigate IR-induced stroke injury. We employed middle cerebral artery occlusion with subsequent reperfusion (MCAO/R) to model ischemic stroke in adult mice. Specifically, we investigated the impact of MMP-3 knockout (KO) on stroke pathophysiology using RNA sequencing (RNA-seq) of stroke brains harvested 48 h post-MCAO. MMP-3 KO significantly reduced brain infarct size following stroke. Notably, RNA-seq analysis showed that MMP-3 KO altered expression of 333 genes (252 downregulated) in male stroke brains and 3768 genes (889 downregulated) in female stroke brains. Functional pathway analysis revealed that inflammation, integrin cell surface signaling, endothelial- and epithelial-mesenchymal transition (EndMT/EMT), and apoptosis gene signatures were decreased in MMP-3 KO stroke brains. Intriguingly, MMP-3 KO downregulated gene signatures more profoundly in females than in males, as indicated by greater negative enrichment scores. Our study underscores MMP-3 inhibition as a promising therapeutic strategy, impacting multiple cellular pathways following stroke.
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Infarto Cerebral , Modelos Animais de Doenças , AVC Isquêmico , Metaloproteinase 3 da Matriz , Camundongos Knockout , Animais , Metaloproteinase 3 da Matriz/genética , Metaloproteinase 3 da Matriz/metabolismo , Masculino , Feminino , Camundongos , AVC Isquêmico/genética , AVC Isquêmico/metabolismo , AVC Isquêmico/patologia , Infarto Cerebral/genética , Infarto Cerebral/patologia , Infarto Cerebral/metabolismo , Infarto da Artéria Cerebral Média/genética , Infarto da Artéria Cerebral Média/metabolismo , Infarto da Artéria Cerebral Média/patologia , Camundongos Endogâmicos C57BL , Transcriptoma , Regulação da Expressão Gênica , Encéfalo/metabolismo , Encéfalo/patologiaRESUMO
BACKGROUND: Lesion detection is one of the most important clinical tasks in positron emission tomography (PET) for oncology. An anthropomorphic model observer (MO) designed to replicate human observers (HOs) in a detection task is an important tool for assessing task-based image quality. The channelized Hotelling observer (CHO) has been the most popular anthropomorphic MO. Recently, deep learning MOs (DLMOs), mostly based on convolutional neural networks (CNNs), have been investigated for various imaging modalities. However, there have been few studies on DLMOs for PET. PURPOSE: The goal of the study is to investigate whether DLMOs can predict HOs better than conventional MOs such as CHO in a two-alternative forced-choice (2AFC) detection task using PET images with real anatomical variability. METHODS: Two types of DLMOs were implemented: (1) CNN DLMO, and (2) CNN-SwinT DLMO that combines CNN and Swin Transformer (SwinT) encoders. Lesion-absent PET images were reconstructed from clinical data, and lesion-present images were reconstructed with adding simulated lesion sinogram data. Lesion-present and lesion-absent PET image pairs were labeled by eight HOs consisting of four radiologists and four image scientists in a 2AFC detection task. In total, 2268 pairs of lesion-present and lesion-absent images were used for training, 324 pairs for validation, and 324 pairs for test. CNN DLMO, CNN-SwinT DLMO, CHO with internal noise, and non-prewhitening matched filter (NPWMF) were compared in the same train-test paradigm. For comparison, six quantitative metrics including prediction accuracy, mean squared errors (MSEs) and correlation coefficients, which measure how well a MO predicts HOs, were calculated in a 9-fold cross-validation experiment. RESULTS: In terms of the accuracy and MSE metrics, CNN DLMO and CNN-SwinT DLMO showed better performance than CHO and NPWMF, and CNN-SwinT DLMO showed the best performance among the MOs evaluated. CONCLUSIONS: DLMO can predict HOs more accurately than conventional MOs such as CHO in PET lesion detection. Combining SwinT and CNN encoders can improve the DLMO prediction performance compared to using CNN only.
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Microglia play a crucial role in synaptic elimination by engulfing dystrophic neurons via triggering receptors expressed on myeloid cells 2 (TREM2). They are also involved in the clearance of beta-amyloid (Aß) plaques in Alzheimer's disease (AD); nonetheless, the driving force behind TREM2-mediated phagocytosis of beta-amyloid (Aß) plaques remains unknown. Here, using advanced 2D/3D/4D co-culture systems with loss-of-function mutations in TREM2 (a frameshift mutation engineered in exon 2) brain organoids/microglia/assembloids, it is identified that the clearance of Aß via TREM2 is accelerated by externalized phosphatidylserine (ePtdSer) generated from dystrophic neurons surrounding the Aß plaques. Moreover, it is investigated whether microglia from both sporadic (CRISPR-Cas9-based APOE4 lines) and familial (APPNL-G-F/MAPT double knock-in mice) AD models show reduced levels of TREM2 and lack of phagocytic activity toward ePtdSer-positive Aß plaques. Herein new insight is provided into TREM2-dependent microglial phagocytosis of Aß plaques in the context of the presence of ePtdSer during AD progression.
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Commensal microbes have the capacity to affect development and severity of autoimmune diseases. Germ-free (GF) animals have proven to be a fine tool to obtain definitive answers to the queries about the microbial role in these diseases. Moreover, GF and gnotobiotic animals can be used to dissect the complex symptoms and determine which are regulated (enhanced or attenuated) by microbes. These include disease manifestations that are sex biased. Here, we review comparative analyses conducted between GF and Specific-Pathogen Free (SPF) mouse models of autoimmunity. We present data from the B6;NZM-Sle1NZM2410/AegSle2NZM2410/AegSle3NZM2410/Aeg-/LmoJ (B6.NZM) mouse model of systemic lupus erythematosus (SLE) characterized by multiple measurable features. We compared the severity and sex bias of SPF, GF, and ex-GF mice and found variability in the severity and sex bias of some manifestations. Colonization of GF mice with the microbiotas taken from B6.NZM mice housed in two independent institutions variably affected severity and sexual dimorphism of different parameters. Thus, microbes regulate both the severity and sexual dimorphism of select SLE traits. The sensitivity of particular trait to microbial influence can be used to further dissect the mechanisms driving the disease. Our results demonstrate the complexity of the problem and open avenues for further investigations.
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Autoimunidade , Modelos Animais de Doenças , Lúpus Eritematoso Sistêmico , Animais , Lúpus Eritematoso Sistêmico/imunologia , Camundongos , Feminino , Humanos , Masculino , Vida Livre de Germes , Índice de Gravidade de Doença , Organismos Livres de Patógenos Específicos , Caracteres Sexuais , Fatores Sexuais , Microbiota/imunologiaRESUMO
Staphylococcus aureus is an important bacterial pathogen that causes a wide variety of human diseases in community and hospital settings. S. aureus employs a diverse array of virulence factors, both surface-associated and secreted, to promote colonization, infection, and immune evasion. Over the past decade, a growing body of research has shown that S. aureus generates extracellular membrane vesicles (MVs) that package a variety of bacterial components, many of which are virulence factors. In this review, we summarize recent advances in our understanding of S. aureus MVs and highlight their biogenesis, cargo, and potential role in the pathogenesis of staphylococcal infections. Lastly, we present some emerging questions in the field.
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Background: Diets rich in minimally processed plant-based foods are recommended to breast cancer patients, and some may have an interest in whole-food, plant-based (WFPB) diets that avoid animal-based foods, added fats, and refined sugars. Within WFPB diets, the intakes of isoflavones, omega-6 polyunsaturated fatty acids (n-6 PUFAs), and omega-3 polyunsaturated FAs (n-3 PUFAs), which have been discussed in reference to breast cancer outcomes, have not been well characterized. Methods: Women with stage IV breast cancer on stable therapy were randomized 2:1 into (1) a WFPB intervention (N = 21) or (2) usual care (N = 11) for 8 weeks. Three meals per day were provided. Outcomes presented here include dietary intake of isoflavones, n-3 and n-6- PUFAs, which were assessed using three-day food records at baseline and 8 weeks. Baseline and 8-week mean intake within groups were compared using the Wilcoxon signed-rank test and between control and intervention groups by a two-sample t-test. Results: The WFPB intervention participants increased their daily consumption of total isoflavones from a mean of 0.8 mg/day to 14.5 mg/day (p < 0.0001) and decreased the n-6:n-3 ratio of their diet from a mean of 9.3 to 3.7 (p < 0.0001). Within the WFPB group, linoleic acid (n-6 PUFA) consumption decreased by a mean of 3.8 g (p = 0.0095), from 12.8 g/day to 9.0 g/day; total n-3 PUFA consumption increased by a mean of 1.1 g (p = 0.0005), from 1.6 g/day to 2.7 g/day. Conclusion: Transitioning to a WFPB diet resulted in significantly increased isoflavone intake and decreased n-6:n-3 ratio in women with breast cancer.
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BACKGROUND: Cerebral organoids (COs) are the most advanced in vitro models that resemble the human brain. The use of COs as a model for Alzheimer's disease (AD), as well as other brain diseases, has recently gained attention. This study aimed to develop a human AD CO model using normal human pluripotent stem cells (hPSCs) that recapitulates the pathological phenotypes of AD and to determine the usefulness of this model for drug screening. METHODS: We established AD hPSC lines from normal hPSCs by introducing genes that harbor familial AD mutations, and the COs were generated using these hPSC lines. The pathological features of AD, including extensive amyloid-ß (Aß) accumulation, tauopathy, and neurodegeneration, were analyzed using enzyme-linked immunosorbent assay, Amylo-Glo staining, thioflavin-S staining, immunohistochemistry, Bielschowsky's staining, and western blot analysis. RESULTS: The AD COs exhibited extensive Aß accumulation. The levels of paired helical filament tau and neurofibrillary tangle-like silver deposits were highly increased in the AD COs. The number of cells immunoreactive for cleaved caspase-3 was significantly increased in the AD COs. In addition, treatment of AD COs with BACE1 inhibitor IV, a ß-secretase inhibitor, and compound E, a γ-secretase inhibitor, significantly attenuated the AD pathological features. CONCLUSION: Our model effectively recapitulates AD pathology. Hence, it is a valuable platform for understanding the mechanisms underlying AD pathogenesis and can be used to test the efficacy of anti-AD drugs.
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Doença de Alzheimer , Peptídeos beta-Amiloides , Organoides , Células-Tronco Pluripotentes , Humanos , Doença de Alzheimer/metabolismo , Doença de Alzheimer/patologia , Doença de Alzheimer/genética , Organoides/metabolismo , Organoides/patologia , Células-Tronco Pluripotentes/metabolismo , Peptídeos beta-Amiloides/metabolismo , Peptídeos beta-Amiloides/genética , Secretases da Proteína Precursora do Amiloide/metabolismo , Secretases da Proteína Precursora do Amiloide/genética , Secretases da Proteína Precursora do Amiloide/antagonistas & inibidores , Proteínas tau/metabolismo , Proteínas tau/genética , Ácido Aspártico Endopeptidases/metabolismo , Ácido Aspártico Endopeptidases/genética , Encéfalo/metabolismo , Encéfalo/patologia , Modelos BiológicosRESUMO
BACKGROUND: Standard measures of response such as Response Evaluation Criteria in Solid Tumors are ineffective for bone lesions, often making breast cancer patients that have bone-dominant metastases ineligible for clinical trials with potentially helpful therapies. In this study we prospectively evaluated the test-retest uptake variability of 2-deoxy-2-[18F]fluoro-D-glucose (18F-FDG) in a cohort of breast cancer patients with bone-dominant metastases to determine response criteria. The thresholds for 95% specificity of change versus no-change were then applied to a second cohort of breast cancer patients with bone-dominant metastases. METHODS: For this study, nine patients with 38 bone lesions were imaged with 18F-FDG in the same calibrated scanner twice within 14 days. Tumor uptake was quantified by the most commonly used PET parameter, the maximum tumor voxel normalized by dose and body weight (SUVmax) and also by the mean of a 1-cc maximal uptake volume normalized by dose and lean-body-mass (SULpeak). The asymmetric repeatability coefficients with confidence intervals for SUVmax and SULpeak were used to determine the limits of 18F-FDG uptake variability. A second cohort of 28 breast cancer patients with bone-dominant metastases that had 146 metastatic bone lesions was imaged with 18F-FDG before and after standard-of-care therapy for response assessment. RESULTS: The mean relative difference of SUVmax and SULpeak in 38 bone tumors of the first cohort were 4.3% and 6.7%. The upper and lower asymmetric limits of the repeatability coefficient were 19.4% and - 16.3% for SUVmax, and 21.2% and - 17.5% for SULpeak. 18F-FDG repeatability coefficient confidence intervals resulted in the following patient stratification using SULpeak for the second patient cohort: 11-progressive disease, 5-stable disease, 7-partial response, and 1-complete response with three inevaluable patients. The asymmetric repeatability coefficients response criteria for SULpeak changed the status of 3 patients compared to the standard Positron Emission Tomography Response Criteria in Solid Tumors of ± 30% SULpeak. CONCLUSION: In evaluating bone tumor response for breast cancer patients with bone-dominant metastases using 18F-FDG SUVmax, the repeatability coefficients from test-retest studies show that reductions of more than 17% and increases of more than 20% are unlikely to be due to measurement variability. Serial 18F-FDG imaging in clinical trials investigating bone lesions in these patients, such as the ECOG-ACRIN EA1183 trial, benefit from confidence limits that allow interpretation of response.
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Background: Hypoxia, a state of low oxygen level within a tissue, is often present in primary and secondary liver tumors. At the molecular level, the tumor cells' response to hypoxic stress induces proteomic and genomic changes which are largely regulated by proteins called hypoxia-induced factors (HIF). These proteins have been found to drive tumor progression and cause resistance to drug- and radiation-based therapies, ultimately contributing to a tumor's poor prognosis. Several imaging modalities have been developed to visualize tissue hypoxia, providing insight into a tumor's microbiology. Methods: A systematic literature search was conducted in PubMed, EMBASE, Cochrane, and Google Scholar for all reports related to hypoxia on liver tumors. All relevant studies were summarized. Results: This review will focus on the impact of hypoxia on liver tumors and review PET-, MRI-, and SPECT-based imaging modalities that have been developed to predict and assess a tumor's response to radiation therapy, with a focus on liver cancers. Conclusion: While there are numerous studies that have evaluated the impact of hypoxia on tumor outcomes, there remains a relative paucity of data evaluating and quantifying hypoxia within the liver. Novel and developing non-invasive imaging techniques able to provide functional and physiological information on tumor hypoxia within the liver may be able to assist in the treatment planning of primary and metastatic liver lesions.
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The exigencies of managing acutely ill residents within nursing homes have led to an increase in ambulance conveyances to the emergency department. This is further compounded by a shortage of adequately trained nursing staff and on-site physicians available around the clock. An acute regional hospital, strategically located in the epicenter of nursing home facilities in Singapore, encountered this challenge on its inception in 2018 within the northeast region. In response, the institution initiated a collaboration, EAGLEcareACT (Enhancing Advance Care Planning, Geriatrics, and End-of-Life Care Acute Care Team), aimed at rectifying the prevailing care disparities between neighboring nursing homes and the hospital. Within the EAGLEcareACT, a systematic and comprehensive approach was undertaken to engage diverse nursing homes, delineate precise needs, and establish mutually shared objectives. This encompassed the provisioning of monitoring of patients treated for acute medical conditions, structured training programs for nursing staff and aids in advance care planning. Teleconsultations with EAGLEcareACT team obviate the immediate necessity for conveyance to the emergency department.
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Casas de Saúde , Humanos , Singapura , Hospitalização , Idoso , Assistência Terminal , Planejamento Antecipado de Cuidados , Transferência de PacientesRESUMO
BACKGROUND: Standard measures of response such as Response Evaluation Criteria in Solid Tumors are ineffective for bone lesions, often making breast cancer patients with bone-dominant metastases ineligible for clinical trials with potentially helpful therapies. In this study we prospectively evaluated the test-retest uptake variability of 2-deoxy-2-[18F]fluoro-D-glucose (18F-FDG) in a cohort of breast cancer patients with bone-dominant metastases to determine response criteria. The thresholds for 95% specificity of change versus no-change were then applied to a second cohort of breast cancer patients with bone-dominant metastases.In this study, nine patients with 38 bone lesions were imaged with 18F-FDG in the same calibrated scanner twice within 14 days. Tumor uptake was quantified as the maximum tumor voxel normalized by dose and body weight (SUVmax) and the mean of a 1-cc maximal uptake volume normalized by dose and lean-body-mass (SULpeak). The asymmetric repeatability coefficients with confidence intervals of SUVmax and SULpeak were used to determine limits of 18F-FDG uptake variability. A second cohort of 28 breast cancer patients with bone-dominant metastases that had 146 metastatic bone lesions was imaged with 18F-FDG before and after standard-of-care therapy for response assessment. RESULTS: The mean relative difference of SUVmax in 38 bone tumors of the first cohort was 4.3%. The upper and lower asymmetric limits of the repeatability coefficient were 19.4% and -16.3%, respectively. The 18F-FDG repeatability coefficient confidence intervals resulted in the following patient stratification for the second patient cohort: 11-progressive disease, 5-stable disease, 7-partial response, and 1-complete response with three inevaluable patients. The asymmetric repeatability coefficients response criteria changed the status of 3 patients compared to standard the standard Positron Emission Tomography Response Criteria in Solid Tumors of ±30% SULpeak. CONCLUSIONS: In evaluating bone tumor response for breast cancer patients with bone-dominant metastases using 18F-FDG uptake, the repeatability coefficients from test-retest studies show that reductions of more than 17% and increases of more than 20% are unlikely to be due to measurement variability. Serial 18F-FDG imaging in clinical trials investigating bone lesions from these patients, such as the ECOG-ACRIN EA1183 trial, benefit from confidence limits that allow interpretation of response.
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PURPOSE: To delineate specific imaging characteristics of solitary fibrous tumors, schwannomas, cavernous venous malformations, and well-circumscribed orbital lymphoma. METHODS: Patients undergoing excisional biopsy of solitary fibrous tumor, schwannomas, cavernous venous malformations, or well-circumscribed orbital lymphoma with preoperative MRIs available for review were identified at 3 academic centers in the United States and Australia. An exploratory statistical analysis was performed to identify important radiologic features, which were subsequently included in a random forest model. Histopathologic correlates were evaluated in representative cases. RESULTS: A total of 91 cases were included with a mean age of 52.9 ± 17.2 years. Nearly all solitary fibrous tumors were located in the anterior or mid orbit (87.5%) and they more commonly demonstrated intralesional heterogeneity on T2-weighted imaging (45.5%) ( p < 0.01). Compared with the other tumors, schwannomas tended to be intraconal (66.7%) and were often in the mid or posterior orbit (83.4%) ( p < 0.01). Cavernous venous malformations characteristically demonstrated progressive contrast enhancement (93.9%; p < 0.01). Most lesions in all 4 groups were hypointense on T1-weighted imaging (80%-100%; p = 0.14) and only well-circumscribed orbital lymphoma tended to also be hypointense on T2 (81.8%) ( p < 0.01). Finally, cases of lymphoma had significantly lower apparent diffusion coefficient ratios (0.9 ± 0.2) ( p < 0.001), while the other 3 groups were not significantly different from one another (cavernous venous malformations: 1.8 ± 0.4; schwannomas: 1.8 ± 0.5; and solitary fibrous tumor: 1.6 ± 0.6) ( p = 0.739). CONCLUSIONS: Key features that aid in the differentiation of these 4 tumors from one another include T2 intensity and homogeneity, early contrast-enhancement pattern, and ADC ratio.
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Imageamento por Ressonância Magnética , Neoplasias Orbitárias , Tumores Fibrosos Solitários , Humanos , Neoplasias Orbitárias/patologia , Neoplasias Orbitárias/diagnóstico , Neoplasias Orbitárias/diagnóstico por imagem , Pessoa de Meia-Idade , Feminino , Masculino , Adulto , Idoso , Tumores Fibrosos Solitários/patologia , Tumores Fibrosos Solitários/diagnóstico , Tumores Fibrosos Solitários/diagnóstico por imagem , Estudos Retrospectivos , Linfoma/diagnóstico , Linfoma/patologia , Linfoma/diagnóstico por imagem , Neurilemoma/patologia , Neurilemoma/diagnóstico , Neurilemoma/diagnóstico por imagem , Idoso de 80 Anos ou mais , Adulto Jovem , Adolescente , BiópsiaRESUMO
PURPOSE: Most cytotoxic drugs are dosed using body surface area (BSA), yet not all cancer patients receive the full BSA-determined dose. Prior work suggests that breast cancer patients who are obese are more likely to experience dose reduction than normal weight patients. However, the factors driving dose reduction remain unclear. METHODS: In 452 women diagnosed with stage I-IIIA primary breast cancer at Kaiser Permanente Northern California, we evaluated the association between obesity and dose reduction, and further explored other factors in relation to dose reduction, including various sociodemographic characteristics, tumor characteristics, and comorbidities. Study participants were a part of the Pathways Study, diagnosed between 2006 and 2013 and treated with cyclophosphamide + doxorubicin, followed by paclitaxel (ACT). Dose reduction was assessed using first cycle dose proportion (FCDP) and average relative dose intensity (ARDI), a metric of dose intensity over the course of chemotherapy. RESULTS: Overall, 8% of participants received a FCDP < 90% and 21.2% had an ARDI < 90%, with dose reduction increasing with body mass index. In adjusted logistic regression models, obese women had 4.1-fold higher odds of receiving an ARDI < 90% than normal weight women (95% CI: 1.9-8.9; p-trend = 0.0006). Increasing age was positively associated with an ADRI < 90%, as was the presence of comorbidity. Dose reduction was less common in later calendar years. CONCLUSION: Results offer insight on factors associated with chemotherapy dosing for a common breast cancer regimen. Larger studies are required to evaluate relevance to other regimens, and further work will be needed to determine whether dose reductions impact outcomes in obese women.
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Neoplasias da Mama , Prestação Integrada de Cuidados de Saúde , Fumaratos , beta-Alanina/análogos & derivados , Humanos , Feminino , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/epidemiologia , Neoplasias da Mama/complicações , Redução da Medicação , Estudos Retrospectivos , Ciclofosfamida , Obesidade/complicações , Obesidade/epidemiologia , Obesidade/tratamento farmacológico , Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversosRESUMO
IMPORTANCE: Extracellular membrane vesicles (MVs) produced by Staphylococcus aureus in planktonic cultures encapsulate a diverse cargo of bacterial proteins, nucleic acids, and glycopolymers that are protected from destruction by external factors. δ-toxin, a member of the phenol soluble modulin family, was shown to be critical for MV biogenesis. Amyloid fibrils co-purified with MVs generated by virulent, community-acquired S. aureus strains, and fibril formation was dependent on expression of the S. aureus δ-toxin gene (hld). Mass spectrometry data confirmed that the amyloid fibrils were comprised of δ-toxin. Although S. aureus MVs were produced in vivo in a localized murine infection model, amyloid fibrils were not observed in the in vivo setting. Our findings provide critical insights into staphylococcal factors involved in MV biogenesis and amyloid formation.
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Infecções Estafilocócicas , Staphylococcus aureus , Animais , Camundongos , Staphylococcus aureus/metabolismo , Amiloide/metabolismo , Proteínas de Bactérias/metabolismo , Infecções Estafilocócicas/microbiologiaRESUMO
Among the 16 two-component systems in the opportunistic human pathogen Staphylococcus aureus, only WalKR is essential. Like the orthologous systems in other Bacillota, S. aureus WalKR controls autolysins involved in peptidoglycan remodeling and is therefore intimately involved in cell division. However, despite the importance of WalKR in S. aureus, the basis for its essentiality is not understood and the regulon is poorly defined. Here, we defined a consensus WalR DNA-binding motif and the direct WalKR regulon by using functional genomics, including chromatin immunoprecipitation sequencing, with a panel of isogenic walKR mutants that had a spectrum of altered activities. Consistent with prior findings, the direct regulon includes multiple autolysin genes. However, this work also revealed that WalR directly regulates at least five essential genes involved in lipoteichoic acid synthesis (ltaS): translation (rplK), DNA compaction (hup), initiation of DNA replication (dnaA, hup) and purine nucleotide metabolism (prs). Thus, WalKR in S. aureus serves as a polyfunctional regulator that contributes to fundamental control over critical cell processes by coordinately linking cell wall homeostasis with purine biosynthesis, protein biosynthesis, and DNA replication. Our findings further address the essentiality of this locus and highlight the importance of WalKR as a bona fide target for novel anti-staphylococcal therapeutics. IMPORTANCE The opportunistic human pathogen Staphylococcus aureus uses an array of protein sensing systems called two-component systems (TCS) to sense environmental signals and adapt its physiology in response by regulating different genes. This sensory network is key to S. aureus versatility and success as a pathogen. Here, we reveal for the first time the full extent of the regulatory network of WalKR, the only staphylococcal TCS that is indispensable for survival under laboratory conditions. We found that WalKR is a master regulator of cell growth, coordinating the expression of genes from multiple, fundamental S. aureus cellular processes, including those involved in maintaining cell wall metabolism, protein biosynthesis, nucleotide metabolism, and the initiation of DNA replication.
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Global spread of multidrug-resistant, hospital-adapted Staphylococcus epidermidis lineages underscores the need for new therapeutic strategies. Here we show that many S. epidermidis isolates belonging to these lineages display cryptic susceptibility to penicillin/ß-lactamase inhibitor combinations under in vitro conditions, despite carrying the methicillin resistance gene mecA. Using a mouse thigh model of S. epidermidis infection, we demonstrate that single-dose treatment with amoxicillin/clavulanic acid significantly reduces methicillin-resistant S. epidermidis loads without leading to detectable resistance development. On the other hand, we also show that methicillin-resistant S. epidermidis is capable of developing increased resistance to amoxicillin/clavulanic acid during long-term in vitro exposure to these drugs. These findings suggest that penicillin/ß-lactamase inhibitor combinations could be a promising therapeutic candidate for treatment of a high proportion of methicillin-resistant S. epidermidis infections, although the in vivo risk of resistance development needs to be further addressed before they can be incorporated into clinical trials.
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Penicilinas , Infecções Estafilocócicas , Humanos , Penicilinas/farmacologia , Penicilinas/uso terapêutico , Inibidores de beta-Lactamases/farmacologia , Staphylococcus epidermidis , Infecções Estafilocócicas/tratamento farmacológico , Ácido Clavulânico/farmacologia , Ácido Clavulânico/uso terapêutico , Amoxicilina/farmacologia , Amoxicilina/uso terapêutico , Testes de Sensibilidade Microbiana , Antibacterianos/farmacologia , Antibacterianos/uso terapêuticoRESUMO
BACKGROUND: The longitudinal response to the COVID-19 vaccines among patients on hemodialysis with and without prior SARS-CoV-2 infection has not been well characterized. METHODS: To guide vaccination strategies in patients on hemodialysis, it is critical to characterize the longevity and efficacy of the vaccine; therefore, we conducted a prospective single-center monthly antibody surveillance study between March 2021 and March 2022 to investigate the dynamic humoral response to a series of COVID-19 mRNA vaccines in patients on hemodialysis with and without prior SARS-CoV-2 infection. Monthly quantitative antibody testing was performed using the Beckman Coulter Access SARS-CoV-2 IgG Antibody Test©, which detects IgG antibodies targeting the receptor binding domain (RBD) of the SARS-CoV-2 spike protein. RESULTS: This cohort of 30 participants (mean age: 61 ± 3 years) predominantly self-identified as African American (97%) and male (53%). Eight participants (27%) had recovered from COVID-19 (recovered) before the vaccine initiation. All participants received two vaccine doses, and 86.6% received a 6-month booster dose. Among patients naïve to COVID-19, the antibody positivity rate (APR) was 55% post-first-dose, 91% post-second-dose, 50% pre-booster at 6 months, 100% post-booster, and 89% at 6 months post-booster. Recovered patients sustained a consistent 100% APR throughout the year. The naïve patients demonstrated lower peak antibody levels post-second-dose than the recovered patients (17.9 ± 3.2 vs. 44.7 ± 5.6, p < 0.001). The peak antibody levels post-booster showed no significant difference between both groups (27.1 ± 3.9 vs. 37.9 ± 8.2, p = 0.20). Two naïve patients contracted COVID-19 during the follow-up period. CONCLUSIONS: The patients naïve to COVID-19 exhibited an attenuated and foreshortened antibody response following two doses of the mRNA vaccines compared with the recovered patients, who maintained 100% APR before the booster dose. The 6-month booster dose counteracted declining immunity and stimulated antibody responses in the naïve patients, even in previously non-responsive patients. This observation implies that different booster vaccination strategies might be required for COVID-19-naïve and -recovered patients. Post-vaccination antibody testing may serve as a valuable tool for guiding vaccination strategies.
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It is crucial that policy makers, healthcare providers and relevant stakeholders understand how integrated care may be improved at our emergency departments (EDs) and what benefits that would bring. The potential that exists for right-siting care of special patient groups who could be managed in an ambulatory setting with the integration of a variety of hospital-based and community-based clinical support services is tremendous. This review describes the best practice and value of integrated care at the EDs. Local evidence is cited and compared with findings from overseas. The opportunities of care transition interventions among discharged patients are outlined, including that for paediatric patients, palliative care patients and patients with chronic diseases. This review also suggests ways to move forward to meet the aim of providing holistic care at EDs through integrated care programmes, innovation and research.
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The opportunistic pathogen Staphylococcus aureus frequently colonizes the inflamed skin of people with atopic dermatitis (AD) and worsens disease severity by promoting skin damage. Here, we show, by longitudinally tracking 23 children treated for AD, that S. aureus adapts via de novo mutations during colonization. Each patient's S. aureus population is dominated by a single lineage, with infrequent invasion by distant lineages. Mutations emerge within each lineage at rates similar to those of S. aureus in other contexts. Some variants spread across the body within months, with signatures of adaptive evolution. Most strikingly, mutations in capsule synthesis gene capD underwent parallel evolution in one patient and across-body sweeps in two patients. We confirm that capD negativity is more common in AD than in other contexts, via reanalysis of S. aureus genomes from 276 people. Together, these findings highlight the importance of the mutation level when dissecting the role of microbes in complex disease.
Assuntos
Dermatite Atópica , Infecções Estafilocócicas , Criança , Humanos , Staphylococcus aureus/genética , Pele , MutaçãoRESUMO
Staphylococcus aureus secretes phenol-soluble modulins (PSMs), a family of small, amphipathic, secreted peptides with multiple biologic activities. Community-acquired S. aureus strains produce high levels of PSMs in planktonic cultures, and PSM alpha peptides have been shown to augment the release of extracellular membrane vesicles (MVs). We observed that amyloids, aggregates of proteins characterized by a fibrillar morphology and stained with specific dyes, co-purified with MVs harvested from cell-free culture supernatants of community-acquired S. aureus strains. δ-toxin was a major component of amyloid fibrils that co-purified with strain LAC MVs, and δ-toxin promoted the production of MVs and amyloid fibrils in a dose-dependent manner. To determine whether MVs and amyloid fibrils were generated under in vivo conditions, we inoculated mice with S. aureus harvested from planktonic cultures. Bacterial MVs could be isolated and purified from lavage fluids recovered from infected animals. Although δ-toxin was the most abundant PSM in lavage fluids, amyloid fibrils could not be detected in these samples. Our findings expand our understanding of amyloid fibril formation in S. aureus cultures, reveal important roles of δ-toxin in amyloid fibril formation and MV biogenesis, and demonstrate that MVs are generated in vivo in a staphylococcal infection model. Importance: Extracellular membrane vesicles (MVs) produced by Staphylococcus aureus in planktonic cultures encapsulate a diverse cargo of bacterial proteins, nucleic acids, and glycopolymers that are protected from destruction by external factors. δ-toxin, a member of the phenol soluble modulin family, was shown to be critical for MV biogenesis. Amyloid fibrils co-purified with MVs generated by virulent, community-acquired S. aureus strains, and fibril formation was dependent on expression of the S. aureus δ-toxin gene ( hld ). Mass spectrometry data confirmed that the amyloid fibrils were comprised of δ-toxin. Although S. aureus MVs were produced in vivo in a localized murine infection model, amyloid fibrils were not observed in the in vivo setting. Our findings provide critical insights into staphylococcal factors involved in MV biogenesis and amyloid formation.