Lung Physiology Research Articles

Broncho-esophageal fistula: When surgery and endoscopy fail, consider physiological lung exclusion

We discuss the case of an esophageal cancer patient treated by chemo and radiotherapy complicated by an esophageal stenosis and an iatrogenic broncho-esophageal fistula. This latter was managed with multiple palliative stenting procedures and colonic surgical bypass. Despite a long disease free survival but decreased quality of life and frailty, we came to the proposal of an extremely unusual form of treatment - physiological lung exclusion, with clinical benefit and so far without any drawbacks related to the procedure.

Unlocking the protective potential of the angiotensin type 2 receptor (AT2R) in acute lung injury and age-related pulmonary dysfunction

Despite its known importance in the cardiovascular system, the specific role and impact of the angiotensin type 2 receptor (AT2R) in lung physiology and pathophysiology remain largely elusive. In this study, we highlight the distinct and specialized lung-specific roles of AT2R, primarily localized to an alveolar fibroblast subpopulation, in contrast to the angiotensin type 1 receptor (AT1R), which is almost exclusively expressed in lung pericytes. Evidence from our research demonstrates that the disruption of AT2R (AT2R-/y), is associated with a surge in oxidative stress and impaired lung permeability, which were further intensified by Hyperoxic Acute Lung Injury (HALI). With aging, AT2R-/y mice show an increase in oxidative stress, premature enlargement of airspaces, as well as increased mortality when exposed to hyperoxia as compared to age-matched WT mice. Our investigation into Losartan, an AT1R blocker, suggests that its primary HALI lung-protective effects are channeled through AT2R, as its protective benefits are absent in AT2R-/y mice. Importantly, a non-peptide AT2R agonist, Compound 21 (C21), successfully reverses lung oxidative stress and TGFβ activation in wild-type (WT) mice exposed to HALI. These findings suggest a possible paradigm shift in the therapeutic approach for lung injury and age-associated pulmonary dysfunction, from targeting AT1R with angiotensin receptor blockers (ARBs) towards boosting the protective function of AT2R.

Optimisation of the air fraction correction for lung PET/CT: addressing resolution mismatch

BackgroundIncreased pulmonary 18\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^{18}{}$$\\end{document}F-FDG metabolism in patients with idiopathic pulmonary fibrosis, and other forms of diffuse parenchymal lung disease, can predict measurements of health and lung physiology. To improve PET quantification, voxel-wise air fractions (AF) determined from CT can be used to correct for variable air content in lung PET/CT. However, resolution mismatches between PET and CT can cause artefacts in the AF-corrected image.MethodsThree methodologies for determining the optimal kernel to smooth the CT are compared with noiseless simulations and non-TOF MLEM reconstructions of a patient-realistic digital phantom: (i) the point source insertion-and-subtraction method, hpts\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$h_{pts}$$\\end{document}; (ii) AF-correcting with varyingly smoothed CT to achieve the lowest RMSE with respect to the ground truth (GT) AF-corrected volume of interest (VOI), hAFC\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$h_{AFC}$$\\end{document}; iii) smoothing the GT image to match the reconstruction within the VOI, hPVC\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$h_{PVC}$$\\end{document}. The methods were evaluated both using VOI-specific kernels, and a single global kernel optimised for the six VOIs combined. Furthermore, hPVC\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$h_{PVC}$$\\end{document} was implemented on thorax phantom data measured on two clinical PET/CT scanners with various reconstruction protocols.ResultsThe simulations demonstrated that at <200\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$<200$$\\end{document} iterations (200 i), the kernel width was dependent on iteration number and VOI position in the lung. The hpts\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$h_{pts}$$\\end{document} method estimated a lower, more uniform, kernel width in all parts of the lung investigated. However, all three methods resulted in approximately equivalent AF-corrected VOI RMSEs (<10%) at ≥\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\ge$$\\end{document}200i. The insensitivity of AF-corrected quantification to kernel width suggests that a single global kernel could be used. For all three methodologies, the computed global kernel resulted in an AF-corrected lung RMSE <10% at ≥\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\ge$$\\end{document}200i, while larger lung RMSEs were observed for the VOI–specific kernels. The global kernel approach was then employed with the hPVC\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$h_{PVC}$$\\end{document} method on measured data. The optimally smoothed GT emission matched the reconstructed image well, both within the VOI and the lung background. VOI RMSE was <10%, pre-AFC, for all reconstructions investigated.ConclusionsSimulations for non-TOF PET indicated that around 200i were needed to approach image resolution stability in the lung. In addition, at this iteration number, a single global kernel, determined from several VOIs, for AFC, performed well over the whole lung. The hPVC\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$h_{PVC}$$\\end{document} method has the potential to be used to determine the kernel for AFC from scans of phantoms on clinical scanners.

Route of administration significantly affects particle deposition and cellular recruitment.

Lung exposures to dusts, pollutants, and other aerosol particulates are known to be associated with pulmonary diseases such as asthma and Chronic Obstructive Pulmonary Disease. These health impacts are attributed to the ability of aerosol components to induce pulmonary inflammation, which promotes tissue remodeling, including fibrosis, tissue degradation, and smooth muscle proliferation. Consequently, the distribution of these effects can have a significant impact on the physiologic function of the lung. In order to study the impact of distribution of inhaled particulates on lung pathogenesis, we compared the effect of different methods of particle delivery. By comparing intranasal versus aerosol delivery of fluorescent microspheres, we observed strikingly distinct patterns of particle deposition; intranasal delivery provided focused deposition concentrated on larger airways, while aerosol delivery showed unform deposition throughout the lung parenchyma. Recognizing that the impacts of inflammatory cells are contingent upon their recruitment and behavior, we postulate that these variations in distribution patterns can result in significant alterations in biological responses. To elucidate the relevance of these findings in terms of biological representation, we subsequently conducted an investigation into the responses elicited by the administration of endotoxin (bacterial Lipopolysaccharide, or LPS) in a transgenic neutrophil reporter mouse model. As with the microsphere results, patterns of recruited neutrophil inflammatory responses matched the delivery method; that is, despite the active migratory behavior of neutrophils, inflammatory histopathology patterns were either focused on large airways (intranasal administration) or diffusely throughout the parenchyma (aerosol). These results demonstrate the importance of modes of aerosol delivery as different patterns of inflammation and tissue remodeling will have distinct impacts on lung physiology.

Abstract 16513: Decreased Pulmonary Blood Flow and Airway Volumes in Patients With Long COVID Syndrome Assessed by Functional Respiratory Imaging

Introduction: In contrast to normal chest X-ray, lung computed tomography (CT), and physiological lung and cardiac functions, many patients with long COVID syndrome suffer from shortness of breath. Hypothesis: The aim of this study was to quantify the pulmonary blood and airway volumes of long COVID patients compared with that of healthy controls. Methods: Patients with long COVID syndromes were included if they had PCR-verified previous (≥3 months) SARS-CoV-2 infection, had normal laboratory (e.g. inflammation, coagulation, cardiac or other organ) parameter, normal pulmonary morphology (chest X-ray and CT) and function (spirometry and body plethysmography). The lung CT images were postprocessed by Functional Respiratory imaging analysis by using 3D reconstruction with automated lung vessel segmentation algorithm. Data of the quantitative images were compared with age, gender, and BMI-matched healthy controls. Results: Thirty patients (45±13 years, 37% male, 25.9±4.3 kg/m^2) at a median time of 256 (118-574) days after a confirmed COVID infection and 30 healthy controls (55±7y, 37% male, 26.3±2.7 kg/m^2) were included. All long COVID patients complained of dyspnoea and 14 (48.3%) patients reported thoracic pain. The total pulmonary blood volume was significantly lower in the long COVID patients compared to controls (190±24.3 mL/m^2 vs230.6±26.2 ml/m^2, p&lt;0.001). Similarly, the capillary-small vessel blood flow (vessel cross sectional area &lt;5 mm^2) was reduced in the long COVID population (118±19 mL vs 132±23 mL, p=0.011). (Figure). The specific image-based airway volume of the distal lung regions was lower than that of the healthy population (11.1±6.74 mL vs 17.33±7.7 mL, p&lt;0.05). Conclusions: Both the reduced global and capillary pulmonary blood flow, and distal airway volumes indicate impaired gas exchange and might explain the pulmonary complaints of patient with long COVID syndromes even severe months after Coronavirus infection.

Bibliometric and visual analysis of hypoxic pulmonary hypertension from 2013 to 2022

Hypoxic pulmonary hypertension (HPH) is caused by chronic persistent hypoxia, which leads to the continuous increase of pulmonary artery pressure and pulmonary vascular resistance. In recent years, there has been a substantial increase in research on HPH. To study the trends of HPH research over the last decade, we used WOSCC to search for relevant research on this topic, and dealt with the relevant information using VOSviewer, CiteSpace, and R-tool. Our results show that the number of publications on HPH has generally increased in the last decade, albeit not significantly, while the average number of citations has been declining year by year. Researchers from the USA top the list with 5498 publications, who widely cooperate with researchers from other countries, followed by those from China. Kurt R. Stenmark has an authoritative position in this field, ranking first with 635 citations. American Journal of Physiology Lung Cellular and Molecular Physiology and Pulmonary Circulation have published 151 articles on HPH in the last 10 years, but the former has higher impact factor and article quality. Circulation proved its leadership in this field with 8812 citations. Our findings reveal the trends in HPH research and should provide researchers with plenty of useful information.

Acute Amelioration of Inflammatory Activity Caused by Endothelin-2 Deficiency during Acute Lung Injury.

In acute lung injury (ALI), a severe insult induces a hyperinflammatory state in the lungs. The mortality rate of severe ALI remains high, and novel mechanistic insights are required to improve therapeutic strategies. Endothelin-2 (Edn2), the least studied isoform of endothelin, is involved in lung physiology and development and can be affected by various factors. One of them is inflammation, and another isoform of endothelin, endothelin-1 (Edn1), affects lung inflammatory responses. Considering the importance of Edn2 in the lungs and how Edn2 works through the same receptors as Edn1, we postulated that Edn2 may affect inflammatory responses that are central to ALI pathophysiology. In this study, we performed 24 hours intratracheal lipopolysaccharide (LPS) instillation or PBS control as an in vivo ALI model in eight-week-old conditional Edn2 knockout mice (Edn2-iKO), with Edn2-floxed mice as controls. Bronchoalveolar lavage (BAL) fluid and tissue were collected after exsanguination and analyzed for its cellular, molecular, functional, and histological inflammatory phenotypes. We found that Edn2-iKO mice displayed a reduced pro-neutrophilic inflammatory phenotype even after acute LPS treatment, shown by the reduction in the overall protein concentration and neutrophil count in bronchoalveolar lavage fluids. Further investigation revealed a reduction in mRNA interferon gamma (IFNγ) level of Edn2-iKO lungs and suppression of its downstream signaling, including phosphorylated level of STAT1 and IL-1β secretion, leading to reduced NFĸB activation. To conclude, Edn2 deletion suppressed acute lung inflammation by reducing neutrophil-mediated IFNγ/STAT1/IL-1β/NFĸB signaling cascade. Targeting Edn2 signaling may be beneficial for the development of novel treatment options for ALI.

Airspace Diameter Map-A Quantitative Measurement of All Pulmonary Airspaces to Characterize Structural Lung Diseases.

(1) Background: Stereological estimations significantly contributed to our understanding of lung anatomy and physiology. Taking stereology fully 3-dimensional facilitates the estimation of novel parameters. (2) Methods: We developed a protocol for the analysis of all airspaces of an entire lung. It includes (i) high-resolution synchrotron radiation-based X-ray tomographic microscopy, (ii) image segmentation using the free machine-learning tool Ilastik and ImageJ, and (iii) calculation of the airspace diameter distribution using a diameter map function. To evaluate the new pipeline, lungs from adult mice with cystic fibrosis (CF)-like lung disease (βENaC-transgenic mice) or mice with elastase-induced emphysema were compared to healthy controls. (3) Results: We were able to show the distribution of airspace diameters throughout the entire lung, as well as separately for the conducting airways and the gas exchange area. In the pathobiological context, we observed an irregular widening of parenchymal airspaces in mice with CF-like lung disease and elastase-induced emphysema. Comparable results were obtained when analyzing lungs imaged with μCT, sugges-ting that our pipeline is applicable to different kinds of imaging modalities. (4) Conclusions: We conclude that the airspace diameter map is well suited for a detailed analysis of unevenly distri-buted structural alterations in chronic muco-obstructive lung diseases such as cystic fibrosis and COPD.

Effect of Nintedanib in Patients with Progressive Pulmonary Fibrosis in Subgroups with Differing Baseline Characteristics.

In the INBUILD trial in patients with progressive pulmonary fibrosis other than idiopathic pulmonary fibrosis (IPF), nintedanib slowed the rate of decline in forced vital capacity (FVC; mL/year) over 52weeks compared with placebo. We assessed the efficacy of nintedanib across subgroups in the INBUILD trial by baseline characteristics. We assessed the rate of decline in FVC over 52weeks and time to progression of interstitial lung disease (ILD) (absolute decline from baseline in FVC % predicted>10%) or death over the whole trial in subgroups based on sex, age, race, body mass index (BMI), time since diagnosis of ILD, FVC % predicted, diffusing capacity of the lungs for carbon monoxide (DLco) % predicted, composite physiologic index (CPI), GAP (gender, age, lung physiology) stage, use of anti-acid therapy and use of disease-modifying antirheumatic drugs (DMARDs) at baseline. The effect of nintedanib versus placebo on reducing the rate of decline in FVC over 52weeks was consistent across the subgroups by baseline characteristics analysed. Interaction p values did not indicate heterogeneity in the treatment effect between these subgroups (p>0.05). Over the whole trial (median follow-up time ∼19months), progression of ILD or death occurred in similar or lower proportions of patients treated with nintedanib than placebo across the subgroups analysed, with no heterogeneity detected between the subgroups. In the INBUILD trial, no heterogeneity was detected in the effect of nintedanib on reducing the rate of ILD progression across subgroups based on demographics, ILD severity or use of anti-acid therapy or DMARDs. These data support the use of nintedanib as a treatment for progressive pulmonary fibrosis. ClinicalTrials.gov Identifier: NCT02999178.

Impact of tidal volume strategy at birth on initiating lung injury in preterm lambs.

Tidal ventilation is essential in supporting the transition to air-breathing at birth, but excessive tidal volume (VT) is an important factor in preterm lung injury. Few studies have assessed the impact of specific VT levels on injury development. Here we used a lamb model of preterm birth to investigate the role of different levels of VT during positive pressure ventilation (PPV) in promoting aeration and initiating early lung injury pathways. VT was delivered as; (i) 7ml/kg throughout (VTstatic), (ii) begun at 3ml/kg and increased to a final VT of 7ml/kg over 3-minutes (VTinc) or (iii) commenced at 7ml/kg, decreased to 3ml/kg and the returned to 7ml/kg (VTalt). VT, inflating pressure, lung compliance and aeration were similar in all groups from 4 minutes, as was post-mortem histology and lung lavage protein concentration. However, transient decrease in VT in the VTalt group caused increased ventilation heterogeneity. Following TMT-based quantitative mass spectrometry proteomics, 1610 proteins were identified in the lung. 3-fold more proteins were significantly altered with VTalt compared with VTstatic or VTinc strategies. Gene set enrichment analysis identified VTalt specific enrichment of immune and angiogenesis pathways and VTstatic enrichment of metabolic processes. Our finding of comparable lung physiology and volutrauma across VT groups challenges the paradigm that there is a need to rapidly aerate the preterm lung at birth. Increased lung injury and ventilation heterogeneity was identified when initial VT was suddenly decreased during respiratory support at birth, further supporting the benefit of a gentle VT approach.

Treatment of Staphylococcus aureus infection with sphingosine in ex vivo perfused and ventilated lungs

Ex vivo lung perfusion (EVLP) has expanded the donor pool for lung transplantation. Pulmonary Staphylococcus aureus infection, especially that caused by multidrug-resistant strains, is a severe threat to posttransplantation outcomes. Sphingosine is a lipid compound that exhibits broad-spectrum antibacterial activity. Therefore, we aimed to evaluate the effects of S aureus infection on EVLP and whether sphingosine administration during EVLP prevents infection with S aureus. Eighteen pigs were randomly assigned to 3 groups: uninfected, infected with S aureus with NaCl treatment, or infected with sphingosine treatment. Bacterial numbers were determined before and after treatment. Sphingosine concentrations in the lung tissues were determined using biochemical assays. Lung histology, lung physiological parameters, perfusate content, lung weight, and cell death were measured to analyze the effects of infection and sphingosine administration on EVLP. Sphingosine administration significantly reduced the bacterial load. The concentration of sphingosine in the bronchial epithelium was elevated after sphingosine administration. S aureus infection increased pulmonary artery pressure and pulmonary vascular resistance. Lung edema, histology scores, lactate and lactate dehydrogenase levels in the perfusate, ΔPO2 in the perfusate, static lung compliance, and lung peak airway pressure did not differ among the groups. Infection of S aureus did not affect the lung function during EVLP but induced higher pulmonary artery pressure and pulmonary vascular resistance. Administration of sphingosine effectively eliminated S aureus without side effects in isolated, perfused, and ventilated pig lungs.

Post-pneumonectomy surgery in prone position: a case report

BackgroundAnesthesia in post-pneumonectomy patients is challenging as pneumonectomy is considered “a disease itself” with impaired oxygenation and ventilation. Literary data for prone ventilation in post-pneumonectomy patients is scarce.Case presentationA 45-year-old female patient with a history of right-sided pneumonectomy 10 years ago with restrictive pulmonary disease underwent uneventful lumbar spine surgery under general anesthesia in the prone position. The lung-protective ventilation using the pressure control mode of ventilation was done.ConclusionsA good understanding of the physiology of the single lung and the concerns of prone ventilation, along with proper preoperative evaluation and optimization, are key to the successful management of such cases.

CFTR dysfunction in smooth muscle drives TGFβ dependent airway hyperreactivity

BackgroundThe primary underlying defect in cystic fibrosis (CF) is disrupted ion transport in epithelia throughout the body. It is unclear if symptoms such as airway hyperreactivity (AHR) and increased airway smooth muscle (ASM) volume in people with CF are due to inherent abnormalities in smooth muscle or are secondary to epithelial dysfunction. Transforming Growth Factor beta 1 (TGFβ) is an established genetic modifier of CF lung disease and a known driver of abnormal ASM function. Prior studies have demonstrated that CF mice develop greater AHR, goblet cell hyperplasia, and ASM hypertrophy after pulmonary TGFβ exposure. However, the mechanism driving these abnormalities in CF lung disease, specifically the contribution of CFTR loss in ASM, was unknown.MethodsIn this study, mice with smooth muscle-specific loss of CFTR function (Cftrfl/fl; SM-Cre mice) were exposed to pulmonary TGFβ. The impact on lung pathology and physiology was investigated through examination of lung mechanics, Western blot analysis, and pulmonary histology.ResultsCftrfl/fl; SM-Cre mice treated with TGFβ demonstrated greater methacholine-induced AHR than control mice. However, Cftrfl/fl; SM-Cre mice did not develop increased inflammation, ASM area, or goblet cell hyperplasia relative to controls following TGFβ exposure.ConclusionsThese results demonstrate a direct smooth muscle contribution to CF airway obstruction mediated by TGFβ. Dysfunction in non-epithelial tissues should be considered in the development of CF therapeutics, including potential genetic therapies.

Sex Differences in Sphingosine-1-Phosphate Levels Are Dependent on Ceramide Synthase 1 and Ceramidase in Lung Physiology and Tumor Conditions.

Sex is a biological variable that can reflect clinical outcomes in terms of quality of life, therapy effectiveness, responsiveness and/or toxicity. Sphingosine-1-phosphate (S1P) is a lipidic mediator whose activity can be influenced by sex. To evaluate whether the S1P axis underlies sex 'instructions' in the lung during physiological and oncological lung conditions, sphingosine and S1P were quantified in the blood of healthy (H) volunteers, lung adenocarcinoma (ADK) and squamous cell carcinoma (SCC) patients of both sexes. S1P receptors and their metabolic enzymes were evaluated in the tissues. Circulating levels of S1P were similar among H female and male subjects and female SCC patients. Instead, male and female ADK patients had lower circulating S1P levels. S1P receptor 3 (S1PR3) was physiologically expressed in the lung, but it was overexpressed in male SCC, and female and male ADK, but not in female SCC patients, who showed a significantly reduced ceramide synthase 1 (CERS1) mRNA and an overexpression of the ceramidase (ASAH1) precursor in lung tumor tissues, compared to male SCC and both male and female ADK patients. These findings highlighted sex differences in S1P rheostat in pathological conditions, but not in physiological conditions, identifying S1P as a prognostic mediator depending on lung cancer histotype.

KCa2 and KCa3.1 Channels in the Airways: A New Therapeutic Target.

K+ channels are involved in many critical functions in lung physiology. Recently, the family of Ca2+-activated K+ channels (KCa) has received more attention, and a massive amount of effort has been devoted to developing selective medications targeting these channels. Within the family of KCa channels, three small-conductance Ca2+-activated K+ (KCa2) channel subtypes, together with the intermediate-conductance KCa3.1 channel, are voltage-independent K+ channels, and they mediate Ca2+-induced membrane hyperpolarization. Many KCa2 channel members are involved in crucial roles in physiological and pathological systems throughout the body. In this article, different subtypes of KCa2 and KCa3.1 channels and their functions in respiratory diseases are discussed. Additionally, the pharmacology of the KCa2 and KCa3.1 channels and the link between these channels and respiratory ciliary regulations will be explained in more detail. In the future, specific modulators for small or intermediate Ca2+-activated K+ channels may offer a unique therapeutic opportunity to treat muco-obstructive lung diseases.

Pulmonary Delivery for miRs: Present and Future Potential

Administration through the respiratory tract can be advantageous, with high drug bioavailability, limited enzymatic activity, reduced dose requirements compared to oral, and potentially diminished side effects. Among the different types of drugs studied for pulmonary delivery, genetic material delivery has gained favorable scientific interest, using polymer-, lipid-, inorganic-, or vector-based nanocarriers. As pulmonary drug delivery has been associated with challenges, including physiological barriers and lung metabolism, the delivery of sensitive molecules such as nucleic acids can exacerbate these challenges. While short-interfering RNAs (siRNAs) have been extensively reported as suitable ribonucleic acid interference (RNAi) candidates for pulmonary delivery, discussion on micro-RNA (miR) pulmonary delivery is limited despite their significant therapeutic potential. Recently, these non-coding RNAs have been explored in targeted or non-targeted pulmonary administration against various diseases. This review addresses the information gap on miR-pulmonary delivery with updated and concentrated literature. We briefly discuss the barriers to lung administration, describe different functional nanocarriers for miR delivery, and provide an extensive literature update on the different miRs and their targeted diseases currently being studied.

Assessment of pulmonary fibrosis induced by paraquat using Al18F-NODA-FAPI-04 PET/CT.

The lack of a highly sensitive method to evaluate paraquat (PQ)-induced pulmonary fibrosis and predict disease progression remains an unresolved clinic issue. Fibroblast activation protein (FAP) may play an important role in the pathogenesis of PQ-induced pulmonary fibrosis. We aimed to evaluate the role of FAP in the PQ-induced pulmonary fibrosis and the utility of fibroblast activation protein inhibitor (FAPI) for positron emission tomography (PET) imaging in PQ-induced pulmonary fibrosis. In our study, two cases of PQ poisoning were presented and FAPI PET/CT was performed as a novel imaging technique. The uptake of FAPI increased in both cases of PQ poisoning. Animal experiments were then performed to validate the findings in the patients. Physiological FAPI lung uptake was higher in mice of the PQ group than in the control group. The results of histological analysis and Western blot were consistent with the findings of PET/CT imaging. The pulmonary fibrosis animal model was developed by intragastric gavage of PQ. PET/CT imaging was performed after injection of FAPI. Lung tissues of mice were collected for fibrosis assessment after imaging. Immunohistochemistry for FAP, histology and Western blot for collagen were performed to further validate the imaging findings. In conclusion, FAPI was involved in the pathogenesis of fibrosis induced by PQ, and PET/CT with FAPI could detect lung fibrogenesis, making it a promising tool to assess early disease activity and predict disease progression.

Nebulised mesenchymal stem cell derived extracellular vesicles ameliorate E. coli induced pneumonia in a rodent model

BackgroundMesenchymal stem cell (MSC) derived extracellular vesicles (EVs) have been proposed as an alternative to cell therapy, creating new possible delivery modalities such as nebulisation. We wished to investigate the therapeutic potential of directly nebulised MSC-EVs in the mitigation of Escherichiacoli-induced pneumonia.MethodsEV size, surface markers and miRNA content were assessed pre- and post-nebulisation. BEAS2B and A459 lung cells were exposed to lipopolysaccharide (LPS) and treated with nebulised bone marrow (BM) or umbilical cord (UC) MSC-EVs. Viability assays (MTT) and inflammatory cytokine assays were performed. THP-1 monocytes were stimulated with LPS and nebulised BM- or UC-EVs and phagocytosis activity was measured. For in vivo experiments, mice received LPS intratracheally (IT) followed by BM- or UC-EVs intravenously (IV) and injury markers assessed at 24 h. Rats were instilled with E. coli bacteria IT and BM- or UC-EVs delivered IV or by direct nebulisation. At 48 h, lung damage was assessed by physiological parameters, histology and inflammatory marker presence.ResultsMSC-EVs retained their immunomodulatory and wound healing capacity after nebulisation in vitro. EV integrity and content were also preserved. Therapy with IV or nebulised MSC-EVs reduced the severity of LPS-induced lung injury and E. coli-induced pneumonia by reducing bacterial load and oedema, increasing blood oxygenation and improving lung histological scores. MSC-EV treated animals also showed lower levels of inflammatory cytokines and inflammatory-related markers.ConclusionsMSC-EVs given IV attenuated LPS-induced lung injury, and nebulisation of MSC-EVs did not affect their capacity to attenuate lung injury caused by E. coli pneumonia, as evidenced by reduction in bacterial load and improved lung physiology.

Life Threatening Hypoxemia Associated with COVID-19 (Review)

COVID-19, which has become a pandemic is caused by coronavirus and led to severe acute respiratory syndrome. Its complication include respiratory incompetence, damage in the muscles of the lung and heart , problems in nervous system and kidney or death. One of the characteristic symptoms of COVID-19 is the low levels of oxygen in patients' blood, a condition known as hypoxemia. Patients with hypoxemia often show the following symptoms: coughing wheezing, difficulty in breathing, headache, feeling disoriented, cyanosis in which the skin, lips, or fingernails become blue colored, even though hypoxemia is diagnosed by some tests, such as analysis of blood gas and pulse oximetry, caution should be considered when pulse oximetry interpreted, because of shifting in the left-sided of the oxyhemoglobin dissociation curve. Hypoxemia causes acute respiratory distress syndrome, that includes inflammation and edema, leadings to impairment in the alveolar homeostasis, modification in the physiology of lung resulting in vascular thrombosis, endothelial inflammation and pulmonary fibrosis, therefore any tardiness in diagnosis and introducing proper treatment can led to mortal outcomes. In this review we present hypoxemia as one of the symptoms resulting from infection with COVID-19 infection, focusing on their types, causes and possible treatment for this condition.

0995 Sleep-related Hypoventilation in a 62-Year-Old Female with a Rare Genetic Neuromuscular Disorder

Abstract Introduction Central Core Myopathy (CCM) is a rare genetic neuromuscular disorder involving a mutation in the ‘Ryanodine Receptor’ (RyR1) gene, also known as the gatekeeper of calcium within the muscle cells. CCM typically manifests as slowly progressive proximal muscle weakness Currently, there is limited data regarding the management of nocturnal hypoventilation in adults with neuromuscular disorders. Report of case(s) We present a 62-year-old woman with CCM, as identified via RyR1 mutation (c14818G&amp;gt;A) on genetic testing, as well as muscle biopsy. This genotype is associated with &amp;lt; 10% respiratory muscle involvement. She presented to the sleep clinic with complaints of morning headaches, non-restorative sleep, and daytime sleepiness. Her polysomnogram (PSG) showed an overall Apnea-Hypopnea-Index in the normal range. However, there was a progressive increase in transcutaneous carbon dioxide levels (PtcCO2), reaching a peak of 53 mmHg during rapid eye movement (REM) sleep from 38 mmHg during wakefulness, consistent with sleep-related neuromuscular hypoventilation. On further evaluation, this patient had no evidence of neuromuscular restrictive lung physiology or overt diaphragmatic dysfunction, as suggested by &amp;lt; 20% variation in the supine forced vital capacity. Moreover, her negative inspiratory force (NIF) value was not less than negative 40. However, in the setting of her sleep-related symptoms and evidence of nocturnal hypoventilation, our team decided to trial non-invasive positive pressure ventilation (NIPPV). Since we had concerns about respiratory alkalosis in NREM sleep in the setting of normal body mass index, normal pulmonary function tests, and hypoventilation limited to REM sleep, the patient was sent for in-lab titration of pressures with measurement of PtcCO2 to appropriately recommend NIPPV settings. The study demonstrated bi-level positive airway pressure settings of IPAP 7 cmH20, EPAP 5 cmH20, and a backup rate of 12/min resulting in sustained eucarbia and steady PtcCO2 levels during both REM and NREM sleep. Conclusion This case highlights the importance of evaluation for nocturnal hypoventilation in symptomatic patients with rare neuromuscular disorders and the potential for symptomatic improvement with treatment with NIPPV. Moreover, the case demonstrates the importance of in-lab titration of pressure settings for NIPPV when hypoventilation is limited to REM sleep, due to concern for iatrogenic hyperventilation and respiratory alkalosis. Support (if any)