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Airway mucociliary clearance (MCC) is required for host defense and is often diminished in chronic lung diseases. Effective clearance depends upon coordinated actions of the airway epithelium and a mobile mucus layer. Dysregulation of the primary secreted airway mucin proteins, MUC5B and MUC5AC, is associated with a reduction in the rate of MCC; however, how other secreted proteins impact the integrity of the mucus layer and MCC remains unclear. We previously identified the gene Bpifb1/Lplunc1 as a regulator of airway MUC5B protein levels using genetic approaches. Here, we show that BPIFB1 is required for effective MCC in vivo using Bpifb1 knockout (KO) mice. Reduced MCC in Bpifb1 KO mice occurred in the absence of defects in epithelial ion transport or reduced ciliary beat frequency. Loss of BPIFB1 in vivo and in vitro altered biophysical and biochemical properties of mucus that have been previously linked to impaired MCC. Finally, we detected colocalization of BPIFB1 and MUC5B in secretory granules in mice and the protein mesh of secreted mucus in human airway epithelia cultures. Collectively, our findings demonstrate that BPIFB1 is an important component of the mucociliary apparatus in mice and a key component of the mucus protein network. NEW & NOTEWORTHY BPIFB1, also known as LPLUNC1, was found to regulate mucociliary clearance (MCC), a key aspect of host defense in the airway. Loss of this protein was also associated with altered biophysical and biochemical properties of mucus that have been previously linked to impaired MCC. [ABSTRACT FROM AUTHOR]

In the United States, millions of adults use electronic cigarettes (e-cigs), and a majority of these users are former or current cigarette smokers. It is unclear, whether prior smoking status affects biological responses induced by e-cigs. In this study, differentiated human nasal epithelial cells (hNECs) from nonsmokers and smokers at air-liquid interface were acutely exposed to the e-cig generated aerosols of humectants, propylene glycol (PG), and glycerol (GLY). Mucin levels were examined in the apical washes, and cytokine levels were assessed in the basolateral supernatants 24 h postexposure. The aerosol from the GLY exposure increased mucin 5, subtype AC (MUC5AC) levels in the apical wash of hNECs from nonsmokers, but not smokers. However, the aerosol from GLY induced pro-inflammatory responses in hNECs from smokers. We also exposed hNECs from nonsmokers and smokers to e-cig generated aerosol from PG:GLY with freebase nicotine or nicotine salt. The PG:GLY with freebase nicotine exposure increased MUC5AC and mucin 5, subtype B (MUC5B) levels in hNECs from nonsmokers, but the nicotine salt exposure did not. The PG:GLY with nicotine salt exposure increased pro-inflammatory cytokines in hNECs from smokers, which was not seen with the freebase nicotine exposure. Taken together, these data indicate that the e-cig generated aerosols from the humectants, mostly GLY, and the type of nicotine used cause differential effects in airway epithelial cells from nonsmokers and smokers. As e-cig use is increasing, it is important to understand that the biological effects of e-cig use are likely dependent on prior cigarette smoke exposure. [ABSTRACT FROM AUTHOR]

The article offers information about the history of the human primary bronchial epithelial (HBE) in respiratory research. It mentions the impacts of the Covid-19 pandemic on the shortages of clinical supplies including masks and hand sanitizers. It discusses that how HBE cells exposed to inflammatory mediators exhibit changes in epithelial structure/function.

Mucoobstructive lung diseases (MOLDs), like cystic fibrosis and chronic obstructive pulmonary disease, affect a spectrum of subjects globally. In MOLDs, the airway mucus becomes hyperconcentrated, increasing osmotic and viscoelastic moduli and impairing mucus clearance. MOLD research requires relevant sources of healthy airway mucus for experimental manipulation and analysis. Mucus collected from endotracheal tubes (ETT) may represent such a source with benefits, e.g., in vivo production, over canonical sample types such as sputum or human bronchial epithelial (HBE) mucus. Ionic and biochemical compositions of ETT mucus from healthy human subjects were characterized and a stock of pooled ETT samples generated. Pooled ETT mucus exhibited concentration-dependent rheologic properties that agreed across spatial scales with reported individual ETT samples and HBE mucus. We suggest that the practical benefits compared with other sample types make ETT mucus potentially useful for MOLD research. [ABSTRACT FROM AUTHOR]

Rationale: Airways obstruction with thick, adherent mucus is a pathophysiologic and clinical feature of muco-obstructive respiratory diseases, including chronic obstructive pulmonary disease, asthma, and cystic fibrosis (CF). Mucins, the dominant biopolymer in mucus, organize into complex polymeric networks via the formation of covalent disulfide bonds, which govern the viscoelastic properties of the mucus gel. For decades, inhaled N-acetylcysteine (NAC) has been used as a mucolytic to reduce mucin disulfide bonds with little, if any, therapeutic effects. Improvement of mucolytic therapy requires the identification of NAC deficiencies and the development of compounds that overcome them.Objectives: Elucidate the pharmacological limitations of NAC and test a novel mucin-reducing agent, P3001, in preclinical settings.Methods: The study used biochemical (e.g., Western blotting, mass spectrometry) and biophysical assays (e.g., microrheology/macrorheology, spinnability, mucus velocity measurements) to test compound efficacy and toxicity in in vitro and in vivo models and patient sputa.Measurements and Main Results: Dithiothreitol and P3001 were directly compared with NAC in vitro and both exhibited superior reducing activities. In vivo, P3001 significantly decreased lung mucus burden in βENaC-overexpressing mice, whereas NAC did not (n = 6-24 mice per group). In NAC-treated CF subjects (n = 5), aerosolized NAC was rapidly cleared from the lungs and did not alter sputum biophysical properties. In contrast, P3001 acted faster and at lower concentrations than did NAC, and it was more effective than DNase in CF sputum ex vivo.Conclusions: These results suggest that reducing the viscoelasticity of airway mucus is an achievable therapeutic goal with P3001 class mucolytic agents. [ABSTRACT FROM AUTHOR]

Increased airway mucus, occurs before infection or structural lung disease in early cystic fibrosis and promotes inflammation. Early changes in cystic fibrosis: Cystic fibrosis (CF) is a genetic disorder caused by mutations in the CFTR gene. The lung is one of the most affected organs. Mucus accumulation, inflammation, and infection are already evident early during development. Understanding early disease pathophysiology could help the development of preventive therapies. Here, Esther et al. analyzed bronchoalveolar lavage fluid (BALF) from toddlers with CF to understand the mechanisms initiating lung disease. Abnormal mucus accumulation was evident in CF BALF, associated with increased mucin and inflammatory marker expression. These abnormalities occurred despite low bacterial infection. The results suggest that mucolytic and anti-inflammatory treatments might be effective during the early stages in CF. Although destructive airway disease is evident in young children with cystic fibrosis (CF), little is known about the nature of the early CF lung environment triggering the disease. To elucidate early CF pulmonary pathophysiology, we performed mucus, inflammation, metabolomic, and microbiome analyses on bronchoalveolar lavage fluid (BALF) from 46 preschool children with CF enrolled in the Australian Respiratory Early Surveillance Team for Cystic Fibrosis (AREST CF) program and 16 non-CF disease controls. Total airway mucins were elevated in CF compared to non-CF BALF irrespective of infection, and higher densities of mucus flakes containing mucin 5B and mucin 5AC were observed in samples from CF patients. Total mucins and mucus flakes correlated with inflammation, hypoxia, and oxidative stress. Many CF BALFs appeared sterile by culture and molecular analyses, whereas other samples exhibiting bacterial taxa associated with the oral cavity. Children without computed tomography–defined structural lung disease exhibited elevated BALF mucus flakes and neutrophils, but little/no bacterial infection. Although CF mucus flakes appeared "permanent" because they did not dissolve in dilute BALF matrix, they could be solubilized by a previously unidentified reducing agent (P2062), but not N-acetylcysteine or deoxyribonuclease. These findings indicate that early CF lung disease is characterized by an increased mucus burden and inflammatory markers without infection or structural lung disease and suggest that mucolytic and anti-inflammatory agents should be explored as preventive therapy. [ABSTRACT FROM AUTHOR]

Rationale: Epidemiologic studies on asthmatics and in vitro data suggest a protective role of T2 inflammation in SARS-CoV-2 infection., Objective: Using a large, multisite cohort, we studied clinical outcomes following SARS-CoV-2 infection in multiple asthma endotypes and examined the effects of T2-directed biologics in infected asthmatics.in Methods: The National COVID Cohort Collaborative (N3C) Data Enclave was used to identify and stratify asthmatic patients by endotype to include non-T2 and T2 asthmatics, as well as exposure to T2-directed biologic therapy. We evaluated the risk of hospitalization, invasive mechanical ventilation, and 90-day mortality by endotype and exposure to biologics., Results: For this study, 402,376 patients met inclusion criteria, of which 138,142 (34%) were characterized as non-T2 and 264,234 (66%) as T2 asthmatics, a group further divided into 104,823 (26%) atopic, 84,440 (21%) eosinophilic, and 74,971 (19%) T2-high asthmatic endotypes. Compared to non-T2 asthmatics, atopic and T2-high asthmatics experienced decreased odds of hospitalization, and 90-day mortality. Conversely, eosinophilic asthmatics experienced higher odds of hospitalization, intubation, and 90-day mortality. Exposure to T2-directed biologic therapies did not alter outcomes after propensity score matching. In contrast, maximum eosinophil count and recent systemic corticosteroid use were directly correlated with increased odds of all outcomes., Conclusions: COVID-19 outcomes differ depending on asthma endotype, with atopic asthmatics experiencing lower odds and eosinophilic asthmatics experiencing higher odds of deleterious outcomes. T2-directed biologic treatment did not alter these outcomes but recent systemic corticosteroid use predisposes all asthmatics patients to adverse outcomes. This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Cystic fibrosis (CF) is characterized by abnormal transepithelial ion transport. However, a description of CF lung disease pathophysiology unifying superficial epithelial and submucosal gland (SMG) dysfunctions has remained elusive. We hypothesized that biophysical abnormalities associated with CF mucus hyperconcentration provide a unifying mechanism. Studies of the anion secretion-inhibited pig airway model of CF revealed elevated SMG mucus concentrations, osmotic pressures, and SMG mucus accumulation. Human airway studies revealed hyperconcentrated CF SMG mucus with raised osmotic pressures and cohesive forces predicted to limit SMG mucus secretion/release. Using proline-rich protein 4 (PRR4) as a biomarker of SMG secretion, CF sputum proteomics analyses revealed markedly lower PRR4 levels compared to healthy and bronchiectasis controls, consistent with a failure of CF SMGs to secrete mucus onto airway surfaces. Raised mucus osmotic/cohesive forces, reflecting mucus hyperconcentration, provide a unifying mechanism that describes disease-initiating mucus accumulation on airway surfaces and in SMGs of the CF lung.

Question: Cystic fibrosis (CF) is characterised by the accumulation of viscous adherent mucus in the lungs. While several hypotheses invoke a direct relationship with cystic fibrosis transmembrane conductance regulator (CFTR) dysfunction ( i.e. acidic airway surface liquid (ASL) pH, low bicarbonate (HCO 3 - ) concentration, airway dehydration), the dominant biochemical alteration of CF mucus remains unknown., Materials/methods: We characterised a novel cell line (CFTR-KO Calu3 cells) and the responses of human bronchial epithelial (HBE) cells from subjects with G551D or F508del mutations to ivacaftor and elexacaftor-tezacaftor-ivacaftor. A spectrum of assays such as short-circuit currents, quantitative PCR, ASL pH, Western blotting, light scattering/refractometry (size-exclusion chromatography with inline multi-angle light scattering), scanning electron microscopy, percentage solids and particle tracking were performed to determine the impact of CFTR function on mucus properties., Results: Loss of CFTR function in Calu3 cells resulted in ASL pH acidification and mucus hyperconcentration (dehydration). Modulation of CFTR in CF HBE cells did not affect ASL pH or mucin mRNA expression, but decreased mucus concentration, relaxed mucus network ultrastructure and improved mucus transport. In contrast with modulator-treated cells, a large fraction of airway mucins remained attached to naïve CF cells following short apical washes, as revealed by the use of reducing agents to remove residual mucus from the cell surfaces. Extended hydration, but not buffers alkalised with sodium hydroxide or HCO 3 - , normalised mucus recovery to modulator-treated cell levels., Conclusion: These results indicate that airway dehydration, not acidic pH and/or low [HCO 3 - ], is responsible for abnormal mucus properties in CF airways and CFTR modulation predominantly restores normal mucin entanglement., Competing Interests: Conflict of interest: C.B. Morrison has nothing to disclose. Conflict of interest: K.M. Shaffer has nothing to disclose. Conflict of interest: K.C. Araba has nothing to disclose. Conflict of interest: M.R. Markovetz has nothing to disclose. Conflict of interest: J.A. Wykoff has nothing to disclose. Conflict of interest: N.L. Quinney has nothing to disclose. Conflict of interest: S. Hao has nothing to disclose. Conflict of interest: M.F. Delion has nothing to disclose. Conflict of interest: A.L. Flen has nothing to disclose. Conflict of interest: L.C. Morton has nothing to disclose. Conflict of interest: J. Liao has nothing to disclose. Conflict of interest: D.B. Hill has nothing to disclose. Conflict of interest: M.L. Drumm has nothing to disclose. Conflict of interest: W.K. O'Neal has nothing to disclose. Conflict of interest: M. Kesimer has nothing to disclose. Conflict of interest: M. Gentzsch has nothing to disclose. Conflict of interest: C. Ehre has nothing to disclose., (Copyright ©The authors 2022. For reproduction rights and permissions contact permissions@ersnet.org.)