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MBio Jul 2024pneumonia (PjP) poses a serious risk to individuals with compromised immune systems, such as individuals with HIV/AIDS or undergoing immunosuppressive therapies for...
pneumonia (PjP) poses a serious risk to individuals with compromised immune systems, such as individuals with HIV/AIDS or undergoing immunosuppressive therapies for cancer or solid organ transplants. Severe PjP triggers excessive lung inflammation, resulting in lung function decline and consequential alveolar damage, potentially culminating in acute respiratory distress syndrome. Non-HIV patients face a 30%-60% mortality rate, emphasizing the need for a deeper understanding of inflammatory responses in PjP. Prior research emphasized macrophages in infections, neglecting neutrophils' role in tissue damage. Consequently, the overemphasis on macrophages led to an incomplete understanding of the role of neutrophils and inflammatory responses. In the current investigation, our RNAseq studies on a murine surrogate model of PjP revealed heightened activation of the NLRP3 inflammasome and NETosis cell death pathways in their lungs. Immunofluorescence staining confirmed neutrophil extracellular trap (NET) presence in the lungs of the -infected mice, validating our findings. Moreover, isolated neutrophils exhibited NETosis when directly stimulated with . Isolated NETs compromised viability , highlighting the potential role of neutrophils in controlling fungal growth and promoting inflammation during pneumonia through NLRP3 inflammasome assembly and NETosis. These pathways, essential for inflammation and pathogen elimination, bear the risk of uncontrolled activation leading to excessive tissue damage and persistent inflammation. This pioneering study is the first to identify the formation of NETs and inflammasomes during infection, paving the way for comprehensive investigations into treatments aimed at mitigating lung damage and augmenting survival rates for individuals with .IMPORTANCE pneumonia (PjP) affects individuals with weakened immunity, such as HIV/AIDS, cancer, and organ transplant patients. Severe PjP triggers lung inflammation, impairing function and potentially causing acute respiratory distress syndrome. Non-HIV individuals face a 30%-60% mortality rate, underscoring the need for deeper insight into PjP's inflammatory responses. Past research focused on macrophages in managing infection and its inflammation, while the role of neutrophils was generally overlooked. In contrast, our findings in -infected mouse lungs showed neutrophil involvement during inflammation and increased expression of NLRP3 inflammasome and NETosis pathways. Detection of neutrophil extracellular traps further indicated their involvement in the inflammatory process. Although beneficial in combating infection, unregulated neutrophil activation poses a potential threat to lung tissues. Understanding the behavior of neutrophils in infections is crucial for controlling detrimental reactions and formulating treatments to reduce lung damage, ultimately improving the survival rates of individuals with PjP.
PubMed: 38953359
DOI: 10.1128/mbio.01409-24 -
MBio Jul 2024causes millions of mucosal infections in humans annually. Hyphal overgrowth on mucosal surfaces is frequently associated with tissue damage caused by candidalysin, a...
UNLABELLED
causes millions of mucosal infections in humans annually. Hyphal overgrowth on mucosal surfaces is frequently associated with tissue damage caused by candidalysin, a secreted peptide toxin that destabilizes the plasma membrane of host cells thereby promoting disease and immunopathology. Candidalysin was first identified in strain SC5314, but recent investigations have revealed candidalysin "variants" of differing amino acid sequence in isolates of , and the related species , and , suggesting that sequence variation among candidalysins may be widespread in natural populations of these species. Here, we analyzed gene sequences from 182 . isolates, 10 . isolates, and 78 . isolates and identified 10, 3, and 2 candidalysin variants in these species, respectively. Application of candidalysin variants to epithelial cells revealed differences in the ability to cause cellular damage, changes in metabolic activity, calcium influx, MAPK signalling, and cytokine secretion, while biophysical analyses indicated that variants exhibited differences in their ability to interact with and permeabilize a membrane. This study identifies candidalysin variants with differences in biological activity that are present in medically relevant species.
IMPORTANCE
Fungal infections are a significant burden to health. Candidalysin is a toxin produced by that damages host tissues, facilitating infection. Previously, we demonstrated that candidalysins exist in the related species and , thereby identifying these molecules as a toxin family. Recent genomic analyses have highlighted the presence of a small number of candidalysin "variant" toxins, which have different amino acid sequences to those originally identified. Here, we screened genome sequences of isolates of , , and and identified candidalysin variants in all three species. When applied to epithelial cells, candidalysin variants differed in their ability to cause damage, activate intracellular signaling pathways, and induce innate immune responses, while biophysical analysis revealed differences in the ability of candidalysin variants to interact with lipid bilayers. These findings suggest that intraspecies variation in candidalysin amino acid sequence may influence fungal pathogenicity.
PubMed: 38953356
DOI: 10.1128/mbio.03351-23 -
MBio Jul 2024an opportunistic fungal pathogen, produces the quorum-sensing molecule farnesol, which we have shown alters the transcriptional response and phenotype of human...
an opportunistic fungal pathogen, produces the quorum-sensing molecule farnesol, which we have shown alters the transcriptional response and phenotype of human monocyte-derived dendritic cells (DCs), including their cytokine secretion and ability to prime T cells. This is partially dependent on the nuclear receptor peroxisome proliferator-activated receptor gamma (PPAR-γ), which has numerous ligands, including the sphingolipid metabolite sphingosine 1-phosphate. Sphingolipids are a vital component of membranes that affect membrane protein arrangement and phagocytosis of by DCs. Thus, we quantified sphingolipid metabolites in monocytes differentiating into DCs by High-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Farnesol increased the activity of serine palmitoyltransferase, leading to increased levels of 3-keto-dihydrosphingosine, dihydrosphingosine, and dihydrosphingosine 1-phosphate and inhibited dihydroceramide desaturase by inducing oxidative stress, leading to increased levels of dihydroceramide and dihydrosphingomyelin species and reduced ceramide levels. Accumulation of dihydroceramides can inhibit mitochondrial function; accordingly, farnesol reduced mitochondrial respiration. Dihydroceramide desaturase inhibition increases lipid droplet formation, which we observed in farnesol-treated cells, coupled with an increase in intracellular triacylglycerol species. Furthermore, inhibition of dihydroceramide desaturase with either farnesol or specific inhibitors impaired the ability of DCs to prime interferon-γ-producing T cells. The effect of farnesol on sphingolipid metabolism, triacylglycerol synthesis, and mitochondrial respiration was not dependent on PPAR-γ. In summary, our data reveal novel effects of farnesol on sphingolipid metabolism, neutral lipid synthesis, and mitochondrial function in DCs that affect their instruction of T cell cytokine secretion, indicating that can manipulate host cell metabolism via farnesol secretion.IMPORTANCE is a common commensal yeast, but it is also an opportunistic pathogen which is one of the leading causes of potentially lethal hospital-acquired infections. There is growing evidence that its overgrowth in the gut can influence diseases as diverse as alcohol-associated liver disease and COVID-19. Previously, we found that its quorum-sensing molecule, farnesol, alters the phenotype of dendritic cells differentiating from monocytes, impairing their ability to drive protective T cell responses. Here, we demonstrate that farnesol alters the metabolism of sphingolipids, important structural components of the membrane that also act as signaling molecules. In monocytes differentiating to dendritic cells, farnesol inhibited dihydroceramide desaturase, resulting in the accumulation of dihydroceramides and a reduction in ceramide levels. Farnesol impaired mitochondrial respiration, known to occur with an accumulation of dihydroceramides, and induced the accumulation of triacylglycerol and oil bodies. Inhibition of dihydroceramide desaturase resulted in the impaired ability of DCs to induce interferon-γ production by T cells. Thus, farnesol production by could manipulate the function of dendritic cells by altering the sphingolipidome.
PubMed: 38953353
DOI: 10.1128/mbio.00732-24 -
MBio Jul 2024Marek's disease virus (MDV) is an oncogenic alphaherpesvirus that causes deadly lymphomas in chickens. In chickens, up to 50% of all peripheral T cells are gamma delta...
Marek's disease virus (MDV) is an oncogenic alphaherpesvirus that causes deadly lymphomas in chickens. In chickens, up to 50% of all peripheral T cells are gamma delta (γδ) T cells. Until now, their role in MDV pathogenesis and tumor formation remains poorly understood. To investigate the role of γδ T cells in MDV pathogenesis, we infected recently generated γδ T cell knockout chickens with very virulent MDV. Strikingly, disease and tumor incidence were highly increased in the absence of γδ T cells, indicating that γδ T cells play an important role in the immune response against MDV. In the absence of γδ T cells, virus replication was drastically increased in the thymus and spleen, which are potential sites of T cell transformation. Taken together, our data provide the first evidence that γδ T cells play an important role in the pathogenesis and tumor formation of this highly oncogenic herpesvirus.IMPORTANCEGamma delta (γδ) T cells are the most abundant T cells in chickens, but their role in fighting pathogens remains poorly understood. Marek's disease virus (MDV) is an important veterinary pathogen, that causes one of the most frequent cancers in animals and is used as a model for virus-induced tumor formation. Our study revealed that γδ T cells play a crucial role in combating MDV, as disease and tumor incidence drastically increased in the absence of these cells. γδ T cells restricted virus replication in the key lymphoid organs, thereby decreasing the likelihood of causing tumors and disease. This study provides novel insights into the role of γδ T cells in the pathogenesis of this highly oncogenic virus.
PubMed: 38953352
DOI: 10.1128/mbio.00315-24 -
American Journal of Hematology Jul 2024Myeloproliferative neoplasms represent a group of clonal hematopoietic disorders of which myelofibrosis (MF) is the most aggressive. In the context of myeloid neoplasms,...
Myeloproliferative neoplasms represent a group of clonal hematopoietic disorders of which myelofibrosis (MF) is the most aggressive. In the context of myeloid neoplasms, there is a growing recognition of the dysregulation of immune response and T-cell function as significant contributors to disease progression and immune evasion. We investigated cytotoxic T-cell exhaustion in MF to restore immune response against malignant cells. Increased expression of inhibitory receptors like CTLA-4 was observed on cytotoxic T cells from MF patients together with a reduced secretion of IFNɣ and TNFɑ. CTLA-4 ligands CD80 and CD86 were increased on MF granulocytes and monocytes highlighting a possible role for myeloid cells in suppressing T-cell activation in MF patients. Unlike healthy donors, the activation of cytotoxic T cells from MF patients was attenuated in the presence of myeloid cells and restored when T cells were cultured alone or treated with anti-CTLA-4. Moreover, anti-CTLA-4 treatment promoted elimination of neoplastic monocytes and granulocytes in a co-culture system with cytotoxic T cells. To test CTLA-4 inhibition in vivo, patient-derived xenografts were generated by transplanting MF CD34+ cells and by infusing homologous T cells in NSGS mice. CTLA-4 blockade reduced human myeloid chimerism and led to T-cell expansion in spleen and bone marrow. Overall, these findings shed light on T-cell dysfunction in MF and suggest that CTLA-4 blockade can boost the cytotoxic T cell-mediated immune response against tumor cells.
PubMed: 38953347
DOI: 10.1002/ajh.27428 -
Chemical Record (New York, N.Y.) Jul 2024pH has been considered one of the paramount factors in bodily functions because most cellular tasks exclusively rely on precise pH values. In this context, the current... (Review)
Review
pH has been considered one of the paramount factors in bodily functions because most cellular tasks exclusively rely on precise pH values. In this context, the current techniques for pH sensing provide us with the futuristic insight to further design therapeutic and diagnostic tools. Thus, pH-sensing (electrochemically and optically) is rapidly evolving toward exciting new applications and expanding researchers' interests in many chemical contexts, especially in biomedical applications. The adaptation of cutting-edge technology is subsequently producing the modest form of these biosensors as wearable devices, which are providing us the opportunity to target the real-time collection of vital parameters, including pH for improved healthcare systems. The motif of this review is to provide insight into trending tech-based systems employed in real-time or in-vivo pH-responsive monitoring. Herein, we briefly go through the pH regulation in the human body to help the beginners and scientific community with quick background knowledge, recent advances in the field, and pH detection in real-time biological applications. In the end, we summarize our review by providing an outlook; challenges that need to be addressed, and prospective integration of various pH in vivo platforms with modern electronics that can open new avenues of cutting-edge techniques for disease diagnostics and prevention.
PubMed: 38953343
DOI: 10.1002/tcr.202300369 -
Microbiology Spectrum Jul 2024The increasing prevalence of invasive fungal pathogens is dramatically changing the clinical landscape of infectious diseases, posing an imminent threat to public...
The increasing prevalence of invasive fungal pathogens is dramatically changing the clinical landscape of infectious diseases, posing an imminent threat to public health. Specifically, , the human opportunistic pathogen, expresses elaborate virulence mechanisms and is equipped with sophisticated adaptation strategies to survive in harsh host environments. This study extensively characterizes Wos2, an Hsp90 co-chaperone homolog, featuring bilateral functioning for both cryptococcal adaptation and the resulting virulence response. In this study, we evaluated the proteome and secretome signatures associated with deletion in enriched and infection-mimicking conditions to reveal Wos2-dependent regulation of the oxidative stress response through global translational reprogramming. The Δ strain demonstrates defective intracellular and extracellular antioxidant protection systems, measurable through a decreased abundance of critical antioxidant enzymes and reduced growth in the presence of peroxide stress. Additional Wos2-associated stress phenotypes were observed upon fungal challenge with heat shock, osmotic stress, and cell membrane stressors. We demonstrate the importance of Wos2 for intracellular lifestyle of during macrophage infection and provide evidence for reduced phagosomal replication levels associated with Δ. Accordingly, Δ featured significantly reduced virulence within impacting fungal burden in a murine model of cryptococcosis. Our study highlights a vulnerable point in the fungal chaperone network that offers a therapeutic opportunity to interfere with both fungal virulence and fitness.IMPORTANCEThe global impact of fungal pathogens, both emerging and emerged, is undeniable, and the alarming increase in antifungal resistance rates hampers our ability to protect the global population from deadly infections. For cryptococcal infections, a limited arsenal of antifungals and increasing rates of resistance demand alternative therapeutic strategies, including an anti-virulence approach, which disarms the pathogen of critical virulence factors, empowering the host to remove the pathogens and clear the infection. To this end, we apply state-of-the-art mass spectrometry-based proteomics to evaluate the impact of a recently defined novel co-chaperone, Wos2, toward cryptococcal virulence using and models of infection. We explore global proteome and secretome remodeling driven by the protein and uncover the novel role in modulating the fungal oxidative stress response. Complementation of proteome findings with infectivity assays demonstrated the protective role of Wos2 within the macrophage phagosome, influencing fungal replication and survival. These results underscore differential cryptococcal survivability and weakened patterns of dissemination in the absence of . Overall, our study establishes Wos2 as an important contributor to fungal pathogenesis and warrants further research into critical proteins within global stress response networks as potential druggable targets to reduce fungal virulence and clear infection.
PubMed: 38953322
DOI: 10.1128/spectrum.00152-24 -
ELife Jul 2024The enhancement of associative synaptic plasticity often results in impaired rather than enhanced learning. Previously, we proposed that such learning impairments can...
The enhancement of associative synaptic plasticity often results in impaired rather than enhanced learning. Previously, we proposed that such learning impairments can result from saturation of the plasticity mechanism (Nguyen-Vu et al., 2017), or, more generally, from a history-dependent change in the threshold for plasticity. This hypothesis was based on experimental results from mice lacking two class I major histocompatibility molecules, MHCI H2-K and H2-D (MHCI KD), which have enhanced associative long-term depression at the parallel fiber-Purkinje cell synapses in the cerebellum (PF-Purkinje cell LTD). Here, we extend this work by testing predictions of the threshold metaplasticity hypothesis in a second mouse line with enhanced PF-Purkinje cell LTD, the knockout mouse model of Fragile X syndrome (FXS). Mice lacking gene expression in cerebellar Purkinje cells (L7- KO) were selectively impaired on two oculomotor learning tasks in which PF-Purkinje cell LTD has been implicated, with no impairment on LTD-independent oculomotor learning tasks. Consistent with the threshold metaplasticity hypothesis, behavioral pre-training designed to reverse LTD at the PF-Purkinje cell synapses eliminated the oculomotor learning deficit in the L7- KO mice, as previously reported in MHCI KDmice. In addition, diazepam treatment to suppress neural activity and thereby limit the induction of associative LTD during the pre-training period also eliminated the learning deficits in L7- KO mice. These results support the hypothesis that cerebellar LTD-dependent learning is governed by an experience-dependent sliding threshold for plasticity. An increased threshold for LTD in response to elevated neural activity would tend to oppose firing rate stability, but could serve to stabilize synaptic weights and recently acquired memories. The metaplasticity perspective could inform the development of new clinical approaches for addressing learning impairments in autism and other disorders of the nervous system.
Topics: Animals; Fragile X Syndrome; Mice; Disease Models, Animal; Fragile X Mental Retardation Protein; Mice, Knockout; Purkinje Cells; Neuronal Plasticity; Male; Learning
PubMed: 38953282
DOI: 10.7554/eLife.92543 -
Zhongguo Yi Xue Ke Xue Yuan Xue Bao.... Jun 2024Alzheimer's disease (AD) is a severe threat to human health and one of the three major causes of human death.Double-stranded RNA-dependent protein kinase (PKR) is an... (Review)
Review
Alzheimer's disease (AD) is a severe threat to human health and one of the three major causes of human death.Double-stranded RNA-dependent protein kinase (PKR) is an interferon-induced protein kinase involved in innate immunity.In the occurrence and development of AD,PKR is upregulated and continuously activated.On the one hand,the activation of PKR triggers an integrated stress response in brain cells.On the other hand,it indirectly upregulates the expression of β-site amyloid precursor protein cleaving enzyme 1 and facilitates the accumulation of amyloid-β protein (Aβ),which could activate PKR activator to further activate PKR,thus forming a sustained accumulation cycle of Aβ.In addition,PKR can promote Tau phosphorylation,thereby reducing microtubule stability in nerve cells.Inflammation in brain tissue,neurotoxicity resulted from Aβ accumulation,and disruption of microtubule stability led to the progression of AD and the declines of memory and cognitive function.Therefore,PKR is a key molecule in the development and progression of AD.Effective PKR detection can aid in the diagnosis and prediction of AD progression and provide opportunities for clinical treatment.The inhibitors targeting PKR are expected to control the activity of PKR,thereby controlling the progression of AD.Therefore,PKR could be a target for the development of therapeutic drugs for AD.
Topics: Alzheimer Disease; Humans; eIF-2 Kinase; Amyloid beta-Peptides; tau Proteins; Phosphorylation; Brain; Amyloid beta-Protein Precursor
PubMed: 38953267
DOI: 10.3881/j.issn.1000-503X.15792 -
Human Vaccines & Immunotherapeutics Dec 2024Many pathogens enter the host through mucosal sites. Thus, interfering with pathogen entry through local neutralization at mucosal sites therefore is an effective... (Review)
Review
Many pathogens enter the host through mucosal sites. Thus, interfering with pathogen entry through local neutralization at mucosal sites therefore is an effective strategy for preventing disease. Mucosally administered vaccines have the potential to induce protective immune responses at mucosal sites. This manuscript delves into some of the latest developments in mucosal vaccination, particularly focusing on advancements in adjuvant technologies and the role of these adjuvants in enhancing vaccine efficacy against respiratory pathogens. It highlights the anatomical and immunological complexities of the respiratory mucosal immune system, emphasizing the significance of mucosal secretory IgA and tissue-resident memory T cells in local immune responses. We further discuss the differences between immune responses induced through traditional parenteral vaccination approaches vs. mucosal administration strategies, and explore the protective advantages offered by immunization through mucosal routes.
Topics: Humans; Immunity, Mucosal; Respiratory Mucosa; Animals; Vaccines; Administration, Mucosal; Adjuvants, Vaccine; Vaccination; Adjuvants, Immunologic; Respiratory Tract Infections; Memory T Cells; Immunoglobulin A, Secretory
PubMed: 38953250
DOI: 10.1080/21645515.2024.2368288