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Witzenrath, M.

Publications and source records attributed to Witzenrath, M..

16 recordsLinked to original sources

Neutrophil-chemoattractant CXCL5 induces lung barrier permeability in acute lung injury

RationaleAcute lung injury is frequently caused by pneumonia, and severity correlates with inflammatory cell recruitment and lung barrier failure. Deciphering drug-targetable pathways is of clinical importance. ObjectivesInvestigation of paracrine and autocrine effects of epithelial-derived chemokine CXCL5 in acute lung injury. MethodsWe assessed the role of CXCL5 and related chemokines in patients with severe pneumonia and primary cells or cell lines challenged with Streptococcus pneumoniae or exposed to mechanical stretch. Furthermore, we evaluated the role of CXCL5 in in vivo models of acute lung injury through use of Cxcl5-deficient mice and in vitro human lung barrier models. ResultsPneumococcal infection and mechanical ventilation were associated with CXCL5 production in human subjects and in mice. CXCL5 was produced by bronchial and alveolar epithelial cells. The alveolar-epithelial barrier was protected in acute lung injury models in Cxcl5-deficient mice, independent of alveolar neutrophil recruitment. Single-cell transcriptomics revealed enhanced cell junctional transcripts in epithelial, but not endothelial cells in Cxcl5-deficient mice. Accordingly, CXCL5 exposure disrupted the barrier function of TNF-primed human primary alveolar epithelial cells, but not pulmonary microvascular endothelial cells. ConclusionsWe describe a novel function of CXCL5 in acute lung injury. Besides its recognized role in recruiting highly inflammatory cells such as neutrophils, CXCL5 increases alveolar-epithelial barrier permeability. Thus, in severe bacterial pneumonia, targeting of CXCL5 as adjunctive therapy to antibiotics may aid in reducing overshooting inflammation as well as stabilizing lung barrier function.

immunology↗

Phage-phage competition and biofilms reduce the efficacy of a combination of two virulent bacteriophages against Pseudomonas aeruginosa

Combined use of virulent bacteriophages (phages) and antibiotics reduces the severity of difficult-to-treat Pseudomonas aeruginosa infections in many patients. In vitro methods that attempt to reproduce more than one physiological state of the pathogens can provide a valuable assessment of antibacterials like phages. Here, by measuring bacterial killing kinetics and individual replication in different growth conditions, including biofilms and a human lung epithelial cell line, we elucidated factors influencing the efficacy of two virulent phages against P. aeruginosa PAO1. A single administration of phages effectively reduced the P. aeruginosa viability in planktonic conditions and infected human lung cell cultures, however, the emergence of phage-resistant variants occurred subsequently. In static biofilms, the phage combination displayed initial inhibition of biofilm dispersal, but sustained control was achieved only by combining phages and meropenem. In contrast, surface-attached biofilms exhibited tolerance to phage and/or meropenem, suggesting a spatiotemporal variation in the antibacterial effect. Moreover, the phage with the shorter lysis time lysed P. aeruginosa more rapidly and selected a specific nucleotide polymorphism that conferred a competitive disadvantage and cross-resistance to the second phage of the combination. The sequential addition of phages resulted in their unimpeded replication with no increase in bacteriolytic activity. These findings highlight biofilm developmental stages, phage-phage competition, and phage resistance as factors restricting the in vitro efficacy of a two-phage combination. Our findings provide a framework for selecting and optimizing phage combinations for enhanced efficacy against P. aeruginosa, a metabolically flexible pathogen that undergoes specific adaptation within the infected lung.

microbiology↗

IGF1R is protective in pneumococcal pneumonia

BackgroundStreptococcus pneumoniae (S.pn) is the most prevalent causal bacterial pathogen in community-acquired pneumonia. Despite appropriate antimicrobial therapy, pneumococcal pneumonia can progress to acute respiratory distress syndrome where actual therapies are mainly supportive, and the discovery of new molecular targets is needed. ObjectiveTo investigate the role of IGF1R (Insulin-like Growth Factor 1 Receptor) in pneumococcal pneumonia. MethodsIgf1r-deficient (UBC-CreERT2; Igf1rfl/fl) and control (Igf1rfl/fl) mice were infected with 5x106 S.pn (PN36) or PBS (sham infected). Mice were sacrificed 48 h after infection. Pulmonary permeability, local inflammatory response, and pulmonary and extra-pulmonary bacterial loads were analyzed. Further, IGF1R protein expression was determined in human lung tissue after S.pn infection and IGF1 and IGF1R levels were determined serum of pneumonia patients. ResultsIn patients and mice infected with S.pn, IGF1 signaling was significantly altered. Igf1r-deficient mice had significantly increased pulmonary permeability after infection with increased pulmonary inflammatory cytokine levels, while inflammatory cell recruitment was not altered compared to infected Igf1rfl/fl control animals. Pulmonary bacterial load was significantly higher in Igf1r-deficient mice, and histological analysis confirmed increased alveolar edema and necrosis compared to infected Igf1rfl/fl control and sham-infected mice. Ex vivo, S.pn caused a decrease in IGF1R protein expression in human lung tissue. ConclusionOur results demonstrate a significant regulation of IGF1R in ex-vivo infected human lung tissue and in serum of S.pn pneumonia patients. Moreover, pneumonia severity was increased in Igf1r-deficient mice upon S.pn infection compared to Igf1rfl/fl control mice, suggesting that IGF1R plays a protective role in pneumococcal pneumonia.

molecular biology↗

Overventilation-induced airspace acidification increases susceptibility to Pseudomonas pneumonia

Ventilator-associated pneumonia (VAP) is the most frequent nosocomial infection in critically ill patients. Local pH variations affect bacterial growth. Whether airway acidification contributes to the pathogenesis and pathophysiology of Pseudomonas aeruginosa (PA)-induced VAP is currently unknown. This study was undertaken to investigate the role and mechanisms of airspace acidification by mechanical ventilation (MV) in PA-induced VAP. C57BL/6J mice were subjected to high (HVt: 34 mL/kg) or low (LVt: 9 mL/kg) tidal volume MV for 4 h. PA was instilled via the tracheal tube, and animals were allowed to recover from sedation and breathe spontaneously for 24 h following extubation. Fluorescence microscopy was applied to determine alveolar pH in ex vivo perfused and ventilated murine lungs. Bacterial growth and adhesion on cyclically stretched A549 and human alveolar epithelial cells was examined. Upon PA infection, HVt mice showed increased alveolo-capillary permeability, elevated lung and blood leukocyte counts, and higher bacterial load in lungs and extrapulmonary organs as compared to LVt controls. HVt MV induced acidification of alveolar lining fluid (ALF) in lungs and decreased pulmonary expression of Na+/H+ exchanger 1 (NHE1). Inhibition of NHE1 enhanced PA growth in vitro on alveolar epithelial cells and increased pulmonary bacterial loads in LVt-MV mice in vivo. In a novel murine VAP model, key characteristics of PA-VAP were replicated. HVt MV induced mild VILI with acidification of airway lining fluid, increasing susceptibility to PA pneumonia. NHE1 was identified as critical factor for MV-induced airspace acidification, and thus as potential target to combat PA-VAP.

immunology↗

Pneumonia induced rise in glucagon promotes endothelial damage and vascular thrombogenicity

BackgroundRecent studies have demonstrated a link between respiratory infections and increased short-term risk of cardiovascular disease (CVD). However, the molecular mechanisms underlying the increased cardiovascular risk after respiratory infections are only poorly understood. Here, we aimed to decipher pathophysiological circuits of pneumonia associated CVD in experimental models of bacterial pneumonia and vascular injury. MethodsC57BL/6J mice were exposed to intranasal inoculation with either Streptococcus pneumoniae (S. pneumoniae) serotype 4 (pneumonia group) or phosphate buffered saline (PBS) (control group). 24 hours post infectionem (p.i.) mice were treated with antibiotics until the end of the study. On day 7 p.i. carotid artery injury (CI) was induced by electric stimulation and vascular repair was analyzed 3 days after injury. Plasma proteomic analyses were performed by Olink Bioscience. Primary human aortic endothelial cells (HAECs) were used to study alterations of the endothelial functional properties, bioenergetic state and thrombogenic potential in vitro. Intravital fluorescence microscopy equipped with video recording was applied to measure thrombus formation in real-time. ResultsBacterial pneumonia impaired repair capacity of the endothelium after vascular injury. Proteomic analyses revealed significantly higher plasma levels of glucagon in mice after recovery from pneumonia relative to controls, which was further confirmed by ELISA detecting glucagon. Mechanistically, we found that glucagon impaired mitochondrial bioenergetics and migratory potential in HAECs and induced an inflammatory response. Moreover, glucagon fostered vascular thrombogenicity as demonstrated by increased thrombocyte adhesion to HAECs and accelerated carotid artery thrombus formation in vivo. Acute application of the glucagon-like peptide-1 receptor (GLP1-R) agonist liraglutide to lower blood glucagon levels, restored vascular repair potential and attenuated vascular thrombogenicity in mice with pneumonia. ConclusionsOur findings reveal a novel mechanism that associates elevated circulatory glucagon levels to dysfunctional endothelium and increased vascular thrombogenicity, suggesting glucagon signaling as a potential therapeutic target to prevent pneumonia-induced cardiovascular events. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=138 SRC="FIGDIR/small/592488v1_ufig1.gif" ALT="Figure 1"> View larger version (32K): org.highwire.dtl.DTLVardef@1dab59eorg.highwire.dtl.DTLVardef@1c9a033org.highwire.dtl.DTLVardef@34a566org.highwire.dtl.DTLVardef@56e33d_HPS_FORMAT_FIGEXP M_FIG C_FIG

physiology↗

Neural Network-Assisted Humanization of COVID-19 Hamster scRNAseq Data Reveals Matching Severity States in Human Disease

Translating findings from animal models to human disease is essential for dissecting disease mechanisms, developing and testing precise therapeutic strategies. The coronavirus disease 2019 (COVID-19) pandemic has highlighted this need, particularly for models showing disease severity-dependent immune responses. Single-cell transcriptomics (scRNAseq) is well poised to reveal similarities and differences between species at the molecular and cellular level with unprecedented resolution. However, computational methods enabling detailed matching are still scarce. Here, we provide a structured scRNAseq-based approach that we applied to scRNAseq from blood leukocytes originating from humans and hamsters affected with moderate or severe COVID-19. Integration of COVID-19 patient data with two hamster models that develop moderate (Syrian hamster, Mesocricetus auratus) or severe (Roborovski hamster, Phodopus roborovskii) disease revealed that most cellular states are shared across species. A neural network-based analysis using variational autoencoders quantified the overall transcriptomic similarity across species and severity levels, showing highest similarity between neutrophils of Roborovski hamsters and severe COVID-19 patients, while Syrian hamsters better matched patients with moderate disease, particularly in classical monocytes. We further used transcriptome-wide differential expression analysis to identify which disease stages and cell types display strongest transcriptional changes. Consistently, hamsters response to COVID-19 was most similar to humans in monocytes and neutrophils. Disease-linked pathways found in all species specifically related to interferon response or inhibition of viral replication. Analysis of candidate genes and signatures supported the results. Our structured neural network-supported workflow could be applied to other diseases, allowing better identification of suitable animal models with similar pathomechanisms across species. Key PointsO_LINeural networks can successfully match disease states between animal models and humans using single-cell data as shown for COVID-19 C_LIO_LIModerately diseased patients best matched Syrian hamster cells; severely diseased patients best matched Roborovski hamster neutrophils C_LI

immunology↗

Enzymatic modulation of the pulmonary glycocalyx alters susceptibility to Streptococcus pneumoniae

The pulmonary epithelial glycocalyx is rich in glycosaminoglycans such as hyaluronan and heparan sulfate. Despite their presence, the precise role of these glycosaminoglycans in bacterial lung infections remains elusive. To address this, we intranasally inoculated mice with Streptococcus pneumoniae in the presence or absence of enzymes targeting pulmonary hyaluronan and heparan sulfate, followed by characterization of subsequent disease pathology, pulmonary inflammation, and lung barrier dysfunction. Enzymatic degradation of hyaluronan and heparan sulfate exacerbated pneumonia in mice, as evidenced by increased disease scores and alveolar neutrophil recruitment. However, targeting epithelial hyaluronan further exacerbated systemic disease, indicated by elevated splenic bacterial load and plasma levels of pro-inflammatory cytokines. In contrast, enzymatic cleavage of heparan sulfate resulted in increased bronchoalveolar bacterial burden, lung damage and pulmonary inflammation in mice infected with Streptococcus pneumoniae. Accordingly, heparinase-treated mice also exhibited disrupted lung barrier integrity as evidenced by higher alveolar edema scores and vascular protein leakage into the airways. This finding was corroborated in a human alveolus-on-a-chip platform, confirming that heparinase treatment also disrupts the human lung barrier. Notably, enzymatic pre-treatment with either hyaluronidase or heparinase also rendered human epithelial cells more sensitive to pneumococcal-induced barrier disruption, as determined by transepithelial electrical resistance measurements, consistent with our findings in murine pneumonia. Taken together, these findings demonstrate the importance of intact hyaluronan and heparan sulfate in controlling pneumococcal virulence, pulmonary inflammation, and epithelial barrier function.

molecular biology↗

Single-cell-resolved interspecies comparison identifies a shared inflammatory axis and a dominant neutrophil-endothelial program in severe COVID-19

Key issues for research of COVID-19 pathogenesis are the lack of biopsies from patients and of samples at the onset of infection. To overcome these hurdles, hamsters were shown to be useful models for studying this disease. Here, we further leveraged the model to molecularly survey the disease progression from time-resolved single-cell RNA-sequencing data collected from healthy and SARS-CoV-2-infected Syrian and Roborovski hamster lungs. We compared our data to human COVID-19 studies, including BALF, nasal swab, and post-mortem lung tissue, and identified a shared axis of inflammation dominated by macrophages, neutrophils, and endothelial cells, which we show to be transient in Syrian and terminal in Roborovski hamsters. Our data suggest that, following SARS-CoV-2 infection, commitment to a type 1 or type 3-biased immunity determines moderate versus severe COVID-19 outcomes, respectively. One-Sentence SummaryActivation of different immunological programs upon SARS-CoV-2 infection determines COVID-19 severity.

immunology↗

IL-33 controls IL-22-dependent antibacterial defense by modulating the microbiota

IL-22 plays a critical role in defending against mucosal infections, but how IL-22 production is regulated is incompletely understood. Here, we show that mice lacking IL-33 or its receptor ST2 (IL-1RL1) were more resistant to Streptococcus pneumoniae lung infection than wild-type animals, and that single nucleotide polymorphisms in IL33 and IL1RL1 were associated with pneumococcal pneumonia in humans. The effect of IL-33 on S. pneumoniae infection was mediated by negative regulation of IL-22 production in innate lymphoid cells (ILCs), but independent of ILC2s as well as IL-4 and IL-13 signaling. Moreover, IL-33s influence on antibacterial defense was dependent on housing conditions of the mice, and mediated by the modulatory effect of IL-33 on the microbiota. Collectively, we provide insight into the bidirectional crosstalk between the innate immune system and the microbiota. We identify a mechanism, dependent on both genetic and environmental factors, that impacts the efficacy of antibacterial immune defense and thus susceptibility to pneumonia. SIGNIFICANCE STATEMENTLower respiratory tract infections are the fifth leading cause of death. Here, we describe a mechanism influenced by genetic and environmental factors that affects the efficacy of pulmonary antibacterial immune responses. We show that IL-33 controls antibacterial defense by regulating the production of IL-22, a cytokine with known functions in antimicrobial immunity in lungs. The effect of IL-33 on IL-22-dependent defense was influenced by the hygienic status of the mice and mediated by IL-33s modulatory effect on the animal microbiota. In addition, genetic variation in genes involved in IL-33 signaling was associated with bacterial pneumonia in humans. Our findings may be important for our understanding of the factors influencing predisposition to lower respiratory tract infections.

immunology↗

Spatial expression of an mRNA encoding Tie2-agonist in the capillary endothelium of the lung prevents pulmonary vascular leakage

Angiopoietin ligands Ang1 and Ang2 and the Tie2 receptor tyrosine kinases form an endothelial signaling pathway regulating vascular homeostasis and controlling vessel permeability, inflammation and angiogenic responses. Whereas Ang1-mediated Tie2 activation reduces inflammation and endothelial permeability, its antagonist, Ang2 increases it. Increased plasma Ang2 levels are associated with poor outcomes in patients with acute lung injury (ALI), as well as in acute respiratory distress syndrome (ARDS). In the study presented here we tested the effect of a novel synthetic, nucleoside-modified mRNA-76 encoding for a hyperactive Ang1 derived fusion protein (COMP-Ang1) on attenuating post-inflammation vascular leakage. COMP-Ang1 mRNA was formulated into a cationic lipid nanoparticle (cLNP) using an optimized mixture of three different lipids and a microfluidic mixing technology. After intravenous injection, the respective mRNA-loaded LNPs were found to be delivered predominantly to the endothelial cells of the lung, while sparing other vascular beds. Also, the specific multimeric folding of the COMP-Ang1 protein complex appeared to be pivotal for its activity in preventing vascular leakage and in restoring the alveolar-endothelial barrier function in the inflamed and injured pulmonary vasculature. The mode of action of mRNA-76, such as its activation of the Tie2 signal transduction pathway, was tested by pharmacological studies in vitro and in vivo by systemic administration in respective mouse models. mRNA-76 was found to prevent lung vascular leakage/lung edema as well as neutrophil infiltration in an LPS-challenging model.

molecular biology↗

A live attenuated vaccine confers superior mucosal and systemic immunity to SARS-CoV-2 variants

Vaccines are a cornerstone in COVID-19 pandemic management. Here, we compare immune responses to and preclinical efficacy of the mRNA vaccine BNT162b2, an adenovirus-vectored spike vaccine, and the live-attenuated-virus vaccine candidate sCPD9 after single and double vaccination in Syrian hamsters. All regimens containing sCPD9 showed superior efficacy. The robust immunity elicited by sCPD9 was evident in a wide range of immune parameters after challenge with heterologous SARS-CoV-2 including rapid viral clearance, reduced tissue damage, fast differentiation of pre-plasmablasts, strong systemic and mucosal humoral responses, and rapid recall of memory T cells from lung tissue. Our results demonstrate that use of live-attenuated vaccines may offer advantages over available COVID-19 vaccines, specifically when applied as booster, and may provide a solution for containment of the COVID-19 pandemic.

immunology↗

Insights into standards of care: dexamethasone and antibodies against COVID-19 in hamster models

RationaleIn face of the ongoing SARS-CoV-2 pandemic, effective and well-understood treatment options are still scarce. While vaccines have proven instrumental in fighting SARS-CoV-2, their efficacy is challenged by vaccine hesitancy, novel variants and short-lasting immunity. Therefore, understanding and optimization of therapeutic options remains essential. ObjectivesWe aimed at generating a deeper understanding on how currently used drugs, specifically dexamethasone and anti-SARS-CoV-2 antibodies, affect SARS-CoV-2 infection and host responses. Possible synergistic effects of both substances are investigated to evaluate combinatorial treatments. MethodsBy using two COVID-19 hamster models, pulmonary immune responses were analyzed to characterize effects of treatment with either dexamethasone, anti-SARS-CoV-2 spike monoclonal antibody or a combination of both. scRNA sequencing was employed to reveal transcriptional response to treatment on a single cell level. Measurements and main resultsDexamethasone treatment resulted in similar or increased viral loads compared to controls. Anti-SARS-CoV-2 antibody treatment alone or combined with dexamethasone successfully reduced pulmonary viral burden. Dexamethasone exhibited strong anti-inflammatory effects and prevented fulminant disease in a severe COVID-19-like disease model. Combination therapy showed additive benefits with both anti-viral and anti-inflammatory potency. Bulk and single-cell transcriptomic analyses confirmed dampened inflammatory cell recruitment into lungs upon dexamethasone treatment and identified a candidate subpopulation of neutrophils specifically responsive to dexamethasone. ConclusionsOur analyses i) confirm the anti-inflammatory properties and indicate possible modes of action for dexamethasone, ii) validate anti-viral effects of anti-SARS-CoV-2 antibody treatment, and iii) reveal synergistic effects of a combination therapy and can thus inform more effective COVID-19 therapies.

molecular biology↗

Altered fibrin clot structure contributes to thrombosis risk in severe COVID-19

The high incidence of thrombotic events suggests a possible role of the contact system pathway in COVID-19 pathology. Here, we demonstrate altered levels of factor XII (FXII) and its activation products in two independent cohorts of critically ill COVID-19 patients in comparison to patients suffering from severe acute respiratory distress syndrome due to influenza virus (ARDS-influenza). Compatible with this data, we report rapid consumption of FXII in COVID-19, but not in ARDS-influenza, plasma. Interestingly, the kaolin clotting time was not prolonged in COVID-19 as compared to ARDS-influenza. Using confocal and electron microscopy, we show that increased FXII activation rate, in conjunction with elevated fibrinogen levels, triggers formation of fibrinolysis-resistant, compact clots with thin fibers and small pores in COVID-19. Accordingly, we observed clot lysis in 30% of COVID-19 patients and 84% of ARDS-influenza subjects. Analysis of lung tissue sections revealed wide-spread extra- and intra-vascular compact fibrin deposits in COVID-19. Together, our results indicate that elevated fibrinogen levels and increased FXII activation rate promote thrombosis and thrombolysis resistance via enhanced thrombus formation and stability in COVID-19.

biochemistry↗

A semisynthetic glycoconjugate provides expanded cross-serotype protection against Streptococcus pneumoniae

Streptococcus pneumoniae infections are the leading cause of child mortality globally. Current vaccines fail to induce a protective immune response towards a conserved part of the pathogen, resulting in new serotypes causing disease. Therefore, new vaccine strategies are urgently needed. Described is a two-pronged approach combining S.pneumoniae proteins, pneumolysin and PspA, with a precisely defined synthetic oligosaccharide, whereby the carrier protein acts as a serotype-independent antigen to provide additional protection. Proof of concept in mice and swine models revealed that the conjugates inhibit colonization of the nasopharynx, decrease the bacterial load and reduce disease severity in the bacteria challenged model. Immunization of piglets provided the first evidence for the immunogenicity and protective potential of synthetic glycoconjugate vaccine in a large animal model. A combination of synthetic oligosaccharides with proteins from the target pathogen opens the path to create broadly cross-protective ("universal") pneumococcal vaccines.

immunology↗

Longitudinal omics in Syrian hamsters integrated with human data unravel complexity of moderate immune responses to SARS-CoV-2

In COVID-19, the immune response largely determines disease severity and is key to therapeutic strategies. Cellular mechanisms contributing to inflammatory lung injury and tissue repair in SARS-CoV-2 infection, particularly endothelial cell involvement, remain ill-defined. We performed detailed spatiotemporal analyses of cellular and molecular processes in SARS-CoV-2 infected Syrian hamsters. Comparison of hamster single-cell sequencing and proteomics with data sets from COVID-19 patients demonstrated inter-species concordance of cellular and molecular host-pathogen interactions. In depth vascular and pulmonary compartment analyses (i) supported the hypothesis that monocyte-derived macrophages dominate inflammation, (ii) revealed endothelial inflammation status and T-cell attraction, and (iii) showed that CD4+ and CD8+ cytotoxic T-cell responses precede viral elimination. Using the Syrian hamster model of self-limited moderate COVID-19, we defined the specific roles of endothelial and epithelial cells, among other myeloid and non-myeloid lung cell subtypes, for determining the disease course.

immunology↗

A SARS-CoV-2 neutralizing antibody protects from lung pathology in a COVID-19 hamster model

The emergence of SARS-CoV-2 led to pandemic spread of coronavirus disease 2019 (COVID-19), manifesting with respiratory symptoms and multi-organ dysfunction. Detailed characterization of virus-neutralizing antibodies and target epitopes is needed to understand COVID-19 pathophysiology and guide immunization strategies. Among 598 human monoclonal antibodies (mAbs) from ten COVID-19 patients, we identified 40 strongly neutralizing mAbs. The most potent mAb CV07-209 neutralized authentic SARS-CoV-2 with IC50 of 3.1 ng/ml. Crystal structures of two mAbs in complex with the SARS-CoV-2 receptor-binding domain at 2.55 and 2.70 [A] revealed a direct block of ACE2 attachment. Interestingly, some of the near-germline SARS-CoV-2 neutralizing mAbs reacted with mammalian self-antigens. Prophylactic and therapeutic application of CV07-209 protected hamsters from SARS-CoV-2 infection, weight loss and lung pathology. Our results show that non-self-reactive virus-neutralizing mAbs elicited during SARS-CoV-2 infection are a promising therapeutic strategy.

immunology↗