Biology subjects

Mall, M. A.

Publications and source records attributed to Mall, M. A..

15 recordsLinked to original sources

bioRxiv2026

Evolution of SARS-CoV-2 reshapes upper airway immunity in children

Children were relatively protected from severe COVID-19 during the early pandemic a phenomenon linked to rapid and heightened innate immune responses in the upper-airways. Although adult upper-airway antiviral responses varied across successive SARS-CoV-2 waves, whether viral evolution similarly reshaped pediatric mucosal immunity remains unclear. Here we used single-cell transcriptomics to profile 229,533 upper-airway cells from 68 unvaccinated children including 17 uninfected controls, spanning the wild-type SARS-CoV-2, Alpha, Delta and Omicron waves. Epithelial interferon responses were primarily determined by time since symptom onset but were, unlike in adults, independent of disease severity. During early infection, anti-viral responses differed across variants without following a progressive pattern of attenuation. Alpha and Delta elicited the strongest interferon programs across epithelial and immune cell populations, whereas Omicron exhibited a shift towards macrophage cytokine signaling and T-cell cytotoxicity. These findings reveal variant-specific remodeling of pediatric upper-airway immunity that fundamentally differs from that described in adults.

immunology↗

bioRxiv2025

Nanobody-Driven Stabilization Synergistically Rescues F508del-CFTR and Reveals an Alternative Active State of the Channel

Defects in protein trafficking underlie many genetic diseases, including cystic fibrosis (CF), where the predominant F508del mutation destabilizes the cystic fibrosis transmembrane conductance regulator (CFTR) channel, leading to its degradation. To provide a protein-specific chaperone, we used lipid nanoparticles to deliver mRNA encoding T2a, a nanobody that thermally stabilizes CFTR via high-affinity binding to nucleotide-binding domain 1 (NBD1). When combined with clinically-approved correctors, T2a considerably improved F508del-CFTR maturation, plasma membrane expression, and channel activity. Single-channel recordings revealed that nanobody binding sustained channel activity by promoting both full open and sub-conductance gating states and protecting F508del-CFTR against thermal deactivation. Because T2a binding to NBD1 prevents the ATP-dependent NBD1-NBD2 association that drives canonical channel opening, the observation of channel activity in the presence of the nanobody suggested adoption of a novel open-channel CFTR structure. This inference was confirmed by cryo-EM analyses of CFTR in the presence of T2a, which revealed a novel open-channel conformation in which NBD1 binds to an alternative site on CFTR incompatible with NBD dimerization. Our findings establish a new paradigm to correct protein trafficking by stabilizing misfolded domains with targeted nanobodies and demonstrate a broadly applicable framework to treat CF and related protein misfolding diseases.

biochemistry↗

bioRxiv2024

Rewired type I IFN signaling is linked to age-dependent differences in COVID-19

Advanced age is the most important risk factor for severe disease or death from COVID-19, but a thorough mechanistic understanding of the molecular and cellular underpinnings is lacking. Multi-omics analysis of samples from SARS-CoV-2 infected persons aged 1 to 84 years, revealed a rewiring of type I interferon (IFN) signaling with a gradual shift from signal transducer and activator of transcription 1 (STAT1) to STAT3 activation in monocytes, CD4+ T cells and B cells with increasing age. Diversion of interferon IFN signaling was associated with increased expression of inflammatory markers, enhanced release of inflammatory cytokines, and delayed contraction of infection-induced CD4+ T cells. A shift from IFN-responsive germinal center B (GCB) cells towards CD69high GCB and atypical B cells corresponded to the formation of IgA in children while complement fixing IgG was dominant in adults. Our data provide a mechanistic basis for inflammation-prone responses to infections and associated pathology during aging. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=144 SRC="FIGDIR/small/619479v1_ufig1.gif" ALT="Figure 1"> View larger version (28K): org.highwire.dtl.DTLVardef@723896org.highwire.dtl.DTLVardef@e12b2aorg.highwire.dtl.DTLVardef@d8de22org.highwire.dtl.DTLVardef@1df96ec_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2024

Systemic effects of cystic fibrosis transmembrane conductance regulator (CFTR) modulators on the blood proteome

Cystic fibrosis (CF), resulting from a dysfunction in the cystic fibrosis transmembrane conductance regulator (CFTR), affects multiple organs through mucus obstruction and differences in secretion. The CFTR modulator drug combination elexacaftor/tezacaftor/ivacaftor (ELX/TEZ/IVA, ETI) has markedly improved clinical symptoms, but its broader molecular and systemic effects remain to be fully elucidated. We employed mass spectrometry-based proteomics to compare the blood proteomes of CF patients treated with the earlier, less effective lumacaftor/ivacaftor (LUM/IVA) combination against those receiving the more potent ELX/TEZ/IVA therapy. Our analysis revealed both specific and common pharmacodynamic signatures associated with inflammation and metabolic processes under each treatment regimen. Notably, ELX/TEZ/IVA therapy exhibited more consistent alterations across patients that were directed towards profiles observed in healthy individuals. Furthermore, by comparing sputum and blood proteomes of ELX/TEZ/IVA treated patients we identified counter-directional changes in the pulmonary surfactant-associated protein B, SFTPB, a potential biomarker of lung tissue repair, which also correlated with lung function improvements. This study provides a comprehensive resource that enhances our understanding of CFTR modulator-driven proteome alterations, offering insights to both systemic and local protein regulation in CF. Our findings indicate that ELX/TEZ/IVA promotes broader systemic health improvements, providing critical insights that could shape future therapeutic strategies in CF.

molecular biology↗

bioRxiv2024

Functional lung imaging identifies peripheral ventilation changes in mice with muco-obstructive lung disease

{beta}-ENaC-Tg mice serve as a relevant model of muco-obstructive lung disease, with impaired mucociliary clearance, mucus obstruction, chronic airway inflammation, structural lung damage, and altered lung function. The aim of this study was to undertake a comprehensive lung function and mechanics analysis of the adult {beta}-ENaC-Tg model. {beta}-ENaC-Tg and wild-type littermates underwent X-ray Velocimetry (XV) scans using a Permetium XV scanner (4DMedical, Melbourne, Australia). For comparative lung mechanics, lung function assessments were conducted with a flexiVent system. XV imaging demonstrated elevated ventilation defect percentage, mean specific ventilation, and ventilation heterogeneity in {beta}-ENaC-Tg mice. Spatial analysis of ventilation maps indicated increased ventilation variability in the peripheral lung regions, as well as an increased proportion of under-ventilated areas. The flexiVent analysis indicated that compared to wild-types, {beta}-ENaC-Tg mice have a significantly more compliant lungs with increased inspiratory capacity, reduced tissue elastance and increased hysteresivity (heterogeneity), suggesting loss of parenchymal integrity. This research highlights the utility of XV imaging in evaluating ventilation defects in the {beta}-ENaC-Tg model and provides a comprehensive lung function analysis.

physiology↗

bioRxiv2024

A Cell-Permeable Nanobody to Restore F508del Cystic Fibrosis Transmembrane Conductance Regulator Activity

Nanobodies have gained considerable attention as particularly promising biopharmaceuticals. However, nanobody-based modalities are currently limited to extracellular targets due to a lack of efficient delivery methods required to reach targets inside cells. In this study, we introduce cell-permeable nanobodies for targeting a disease-relevant intracellular protein, namely the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel with the most common cystic fibrosis (CF)-causing mutation F508del. We employ cell-penetrating peptides (CPPs) to deliver a CFTR-binding nanobody (NB1) that stabilizes misfolded F508del-CFTR and prevents its degradation to restore its function. Our data show that conjugation of a disulfide-linked CPP in combination with a cell-surface anchored CPP-additive enables intracellular delivery of NB1 into CF bronchial epithelial cells, which promotes maturation and trafficking of F508del-CFTR protein to the apical cell membrane. Furthermore, we demonstrate that the cell-permeable nanobody restores CFTR chloride channel function, which can be further enhanced by the clinically approved small molecule CFTR potentiator ivacaftor. This study highlights the use of cell-permeable nanobodies for modulation of protein function and illustrates their therapeutic potential as next-generation biopharmaceuticals for intracellular delivery and targeting. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=122 SRC="FIGDIR/small/591242v1_ufig1.gif" ALT="Figure 1"> View larger version (53K): org.highwire.dtl.DTLVardef@45d357org.highwire.dtl.DTLVardef@362e56org.highwire.dtl.DTLVardef@11c4dc2org.highwire.dtl.DTLVardef@13512b1_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗

bioRxiv2024

Reflection confocal microscopy for quantitative assessment of airway surface liquid dysregulation and pharmacological rescue in cystic fibrosis under near-physiological conditions

Proper regulation of airway surface liquid (ASL) is essential for effective mucociliary clearance (MCC) in healthy airways, and ASL depletion due to deficient cystic fibrosis transmembrane conductance regulator (CFTR)-mediated anion/fluid secretion plays an important role in the pathogenesis of mucociliary dysfunction and chronic muco-obstructive lung disease in patients with cystic fibrosis (CF). The current standard for quantitative measurements of ASL height is confocal fluorescence microscopy that has the disadvantage that it requires apical addition of volume for fluorescent staining, and hence perturbation of the ASL. Therefore, our aim was to develop a method that enables studies of ASL regulation under unperturbed conditions using reflected light by confocal microscopy of primary airway epithelial cultures grown at air-liquid interface (ALI). After apical volume addition to primary tracheal mouse cultures, confocal reflection microscopy yielded comparable ASL height as confocal fluorescence microscopy on cultures of wild-type mice, and was sensitive to detect ASL depletion on cultures of {beta}ENaC-Tg mice. Under unperturbed conditions, ASL determined by confocal reflection microscopy was significantly higher in wild-type and {beta}ENaC-Tg mice compared to values obtained by confocal fluorescence microscopy. Studies in normal and CF primary human airway epithelial cultures showed that confocal reflection microscopy was sensitive to detect effects of low temperature rescue and pharmacological modulation including improvement of CFTR function by VX-809 and VX-770 in cultures from CF patients with the F508del mutation. Our results support confocal reflection microscopy as a novel sensitive technique for quantitative studies of ASL regulation and response to therapeutic intervention under unperturbed near-physiological conditions in healthy and CF airways. NEW & NOTEWORTHYMeasurement of airway surface liquid (ASL) height by confocal fluorescence microscopy is an important tool to investigate ASL dysregulation and effects of therapeutic strategies aiming at restoring ASL volume to improve mucociliary clearance and lung function in patients with cystic fibrosis. However, confocal fluorescence microscopy has the disadvantage that it requires apical addition of volume for fluorescent staining of the ASL leading to perturbation of its height and composition. Here, we developed confocal reflection microscopy as a new method that enables quantitative assessment of ASL on highly-differentiated primary airway epithelial cultures under unperturbed near-physiological conditions by detection of refracted light.

cell biology↗

bioRxiv2024

A comprehensive characterization of the viscoelastic properties of Bovine Submaxillary Mucin (BSM) and the effect of additives

This study presents a comprehensive characterization of the viscoelastic and structural properties of Bovine Submaxillary Mucin (BSM), which is widely used as a commercial source to conduct mucus-related research. We conducted concentration studies of BSM and examined the effects of various additives - NaCl, CaCl2, lysozyme, and DNA - on its rheological behavior. A notable connection between BSM concentration and viscoelastic properties was observed, particularly under varying ionic conditions. The rheological spectra could be well-described by a fractional Kelvin-Voigt Model with a minimum of model parameters. A detailed proteomics analysis provided insight into the molecular interactions within BSM, showing MUC19 as main component. Cryo-scanning electron microscopy allowed to visualize the network structure in relation to the rheological data. By elucidating the complex interplay between mucin concentration, environmental conditions, and viscoelastic properties, this research significantly contributes to the field of mucus research and lays an important basis for its further advancement.

biophysics↗

bioRxiv2024

Ileal mucus viscoelastic properties differ in Crohns disease

Crohns disease (CD) is an inflammatory bowel disease (IBD) that can affect any part of the gastrointestinal tract, frequently involving the terminal ileum. While colonic mucus alterations in CD patients have been described, terminal ileal mucus and its mechanobiological properties have been neglected. Our study is the first of its kind to decipher the viscoelastic and network properties of ileal mucus. With that aim, oscillatory rheological shear measurements based on an airway mucus protocol that was thoroughly validated for ileal mucus were performed. Our pilot study analyzed terminal ileum mucus from controls (n=11) and CD patients (n=11). Mucus network structure was visualized by scanning electron microscopy (SEM). Interestingly, a statistically significant increase in viscoelasticity as well as a decrease in mesh size was observed in ileal mucus from CD patients compared to controls. Furthermore, rheological data were analyzed in relation to study participants clinical characteristics, such as inflammatory status, revealing noteworthy trends. In conclusion, this study provides the first data on the viscoelastic properties and structure of human ileal mucus in the healthy state and in CD, demonstrating significant alterations between groups and highlighting the need for further research on mucus and its effect on the underlying epithelial barrier.

biophysics↗

bioRxiv2023

Increased pulmonary monocyte infiltration and attenuated phagocytosis defines perinatal dysfunction of innate immunity in Cystic Fibrosis

In Cystic Fibrosis (CF) patients, cycles of infection and inflammation lead to fatal lung damage. While diminished mucus clearance is restored by highly effective CFTR modulator therapy, inflammation and infection persist in treated patients, suggesting alternative mechanisms may contribute to impaired immunity in CF. Here, we made use of a CF pig model to investigate the innate immune system at birth, before the onset of infection. We observed a substantial change in the composition of tissue resident immune cells towards emergency myelopoiesis, accompanied by increased infiltration of monocytes into CF lungs. A more immature status in the transcriptome profile of classical monocytes in CF pigs and preschool children with CF correlated with reduced phagocytic capacity, confirming a congenital and translationally conserved aberration of the immune system in CF. The lack of CFTR expression in circulating monocytes indicates an indirect etiology of these effects and suggests that additional immunological treatments are necessary for CF patients. One Sentence SummaryIncreased infiltration of lung tissue by monomyeloid cells and their impaired phagocytic potential cause dysfunctional imprinting of mucosal immunity in Cystic Fibrosis airways at birth and suggest early and specific treatment of the innate immune system in patients.

immunology↗

bioRxiv2023

Longitudinal Micro-Computed Tomography Detects Onset and Progression of Pulmonary Fibrosis in Conditional Nedd4-2 Deficient Mice

ObjectivesIdiopathic pulmonary fibrosis (IPF) is a fatal lung disease which is usually diagnosed late in advanced stages. Little is known about the subclinical development of IPF. We previously generated a mouse model with conditional Nedd4-2 deficiency (Nedd4-2-/-) that develops IPF-like lung disease. The aim of this study was to characterize the onset and progression of IPF-like lung disease in conditional Nedd4-2-/- mice by longitudinal micro- computed tomography (CT). MethodsIn vivo micro-CT was performed longitudinally in control and conditional Nedd4- 2-/- mice at 1, 2, 3, 4 and 5 months after doxycycline induction. Further, terminal in vivo micro-CT followed by pulmonary function testing and post mortem micro-CT was performed in age-matched mice. Micro-CT images were evaluated for pulmonary fibrosis using an adapted fibrosis scoring system. ResultsMicro-CT is sensitive to detect onset and progression of pulmonary fibrosis in vivo and to quantify distinct radiological IPF-like features along disease development in conditional Nedd4-2-/- mice. Nonspecific interstitial alterations were detected from 3 months, whereas key features such as honeycombing-like lesions were detected from 4 months onwards. Pulmonary function inversely correlated with in vivo (r=-0.725) and post mortem (r=-0.535) micro-CT fibrosis scores. ConclusionLongitudinal micro-CT enables in vivo monitoring of onset and progression and detects radiologic key features of IPF-like lung disease in conditional Nedd4-2-/- mice. Our data support micro-CT as sensitive quantitative endpoint for preclinical evaluation of novel antifibrotic strategies. NEW & NOTEWORTHYIPF diagnosis, particularly in early stages, remains challenging. In this study micro-CT is used in conditional Nedd4-2-/- mice to closely monitor the onset and progression of IPF-like lung disease. This allowed us to track for the first time how nonspecific lung lesions develop into key IPF-like features. This approach offers a non-invasive method to monitor pulmonary fibrosis in vivo, providing a quantitative endpoint for preclinical evaluation of novel antifibrotic strategies.

pathology↗

bioRxiv2023

Enhanced Airway Epithelial Response to SARS-CoV-2 Infection in Children is Critically Tuned by the Cross-Talk Between Immune and Epithelial Cells

To cope with novel virus infections to which no prior adaptive immunity exists, the body strongly relies on the innate immune system. In such cases, including infections with SARS-CoV-2, children tend to fair better than adults. In the context of COVID-19, it became evident that a rapid interferon response at the site of primary infection is key for successful control of the virus and prevention of severe disease. The airway epithelium of children was shown to exhibit a primed state already at homeostasis and to respond particularly well to SARS-CoV-2 infection. However, the underlying mechanism for this priming remained elusive. Here we show that interactions between airway mucosal immune cells and epithelial cells are stronger in children, and via cytokine-mediated signaling lead to IRF-1-dependent upregulation of the viral sensors RIG-I and MDA5. Based on a cellular in vitro model we show that stimulated human peripheral blood mononuclear cells (PBMC) can induce a robust interferon-beta response towards SARS-CoV-2 in a lung epithelial cell line otherwise unresponsive to this virus. This is mediated by type I interferon, interferon-gamma and TNF, and requires induction of both, RIG-I and MDA5. In single cell-analysis of nasal swab samples the same cytokines are found to be elevated in mucosal immune cells of children, correlating with elevated epithelial expression of viral sensors. In vitro analysis of PBMC derived from healthy adolescents and adults confirm that immune cells of younger individuals show increased cytokine production and potential to prime epithelial cells. In co-culture with SARS-CoV-2-infected A549 cells, PBMC from adolescents significantly enhance the antiviral response. Taken together, our study suggests that higher numbers and a more vigorous activity of innate immune cells in the airway mucosa of children tune the set-point of the epithelial antiviral system. This likely is a major contributor to the robust immune response to SARS-CoV-2 in children. Our findings shed light on the molecular underpinnings of the stunning resilience of children towards severe COVID-19, and may propose a novel concept for immunoprophylactic treatments.

immunology↗

bioRxiv2020

Tamoxifen reduces inflammatory infiltration of neutrophils in the airways.

ABSTRACTTamoxifen is a drug of choice for treatment of breast cancer but it has also been reported to bear anti-inflammatory activity. Previously, we have observed that tamoxifen treatment successfully reduced inflammation in horses affected by equine asthma syndrome. More notorious, tamoxifen was effective at reducing the infiltration of neutrophils in the inflamed airways by a mechanism that increases efferocytosis, allowing the resolution of inflammation. Due to the emerging increase in patients with chronic inflammatory lung diseases, there is an urgent need for therapies that help reduce airway inflammation. Thus we tested the effect of tamoxifen on airway neutrophil infiltration by using three different mouse models for acute and chronic inflammation of the lung. We found that the drug was able to produce a significant reduction in neutrophils in all scenarios. Ussing chamber experiments demonstrated that tamoxifen has no effect on fluid secretion and absorption, discarding a possible reduction in mucociliary clearance due to the known ion-channel blocking effects of tamoxifen. Since this drug has been largely used in human medicine, tamoxifen might be a “low hanging fruit” for a novel anti-inflammatory therapy for airway diseases characterized by neutrophilic inflammation.Competing Interest StatementThe authors have declared no competing interest.View Full Text

pharmacology and toxicology↗

bioRxiv2020

Lack of Kcnn4 improves mucociliary clearance in muco-obstructive lung disease.

Airway mucociliary clearance (MCC) is the main mechanism of lung defense keeping the airways free of infection and mucus obstruction. Airways surface liquid (ASL) volume, ciliary beating and mucus are central for proper MCC, and are critically regulated by sodium (Na+) absorption and anion secretion. Impaired MCC is a key feature of muco-obstructive disease. The calcium-activated potassium (K+)channel KCa.3.1, encoded by the Kcnn4 gene, participates in intestinal ion secretion and previous studies showed that its activation increase Na+ absorption in airway epithelia, suggesting that hyperpolarization induced by KCa3.1 was sufficient to drive Na+ absorption. However, its role in airway epithelial function is not fully understood. We therefore aimed to elucidate the role of KCa3.1 in MCC in a genetically engineered mouse model. We show that KCa3.1 inhibition reduced Na+ absorption in mouse and human airway epithelium. Furthermore, the genetic deletion of Kcnn4 enhanced cilia beating frequency (CBF) and MCC ex vivo and in vivo. Kcnn4 was silenced in the Scnn1b-transgenic mouse (Scnn1btg/+), a model of muco-obstructive lung disease triggered by increased epithelial Na+-absorption, leading to improvements in MCC and reduction of Na+-absorption. KCa3.1 deletion did not change the amount of mucus but did reduce mucus adhesion, neutrophil infiltration and emphysema. Our data support that KCa3.1 inhibition attenuated muco-obstructive disease in the Scnn1btg/+ mice. K+-channel modulation may be a novel therapeutic strategy to treat muco-obstuctive lung diseases.

physiology↗

bioRxiv2019

Antigen-driven PD1+Tox+Eomes+ and PD1+Tox+BHLHE40+ synovial T lymphocytes regulate chronic inflammation in situ

Introduction/AbstractT lymphocytes accumulate in inflamed tissues of patients with chronic inflammatory diseases (CIDs) and express pro-inflammatory cytokines upon re-stimulation in vitro1-29. Further, a significant genetic linkage to MHC genes suggests that T lymphocytes play an important role in the pathogenesis of CIDs including juvenile idiopathic arthritis (JIA)30-33. However, the functions of T lymphocytes in established disease remain elusive. Here we dissect the heterogeneity of synovial T lymphocytes in JIA patients by single cell RNA-sequencing. We identify subpopulations of T lymphocytes expressing genes reflecting recent activation by antigen in situ. A PD-1+TOX+EOMES+ population of CD4+ T lymphocytes expressed immune regulatory genes and chemoattractant genes for myeloid cells. A PD-1+TOX+BHLHE40+ population of CD4+, and a mirror population of CD8+ T lymphocytes expressed genes driving inflammation, and genes supporting B lymphocyte activation. This analysis points out that multiple types of T lymphocytes have to be targeted for therapeutic regeneration of tolerance in arthritis.

immunology↗