The Th17 pathway in cystic fibrosis lung disease

A Critical Review on the Role of Probiotics in Lung Cancer Biology and Prognosis

Lung cancer remains the leading cause of cancer-related deaths worldwide. According to the American Cancer Society (ACS), it ranks as the second most prevalent type of cancer globally. Recent findings have highlighted bidirectional gut-lung interactions, known as the gut-lung axis, in the pathophysiology of lung cancer. Probiotics are live microorganisms that boost host immunity when consumed adequately. The immunoregulatory mechanisms of probiotics are thought to operate through the generation of various metabolites that impact both the gut and distant organs (e.g., the lungs) through blood. Several randomized controlled trials have highlighted the pivotal role of probiotics in gut health especially for the prevention and treatment of malignancies, with a specific emphasis on lung cancer. Current research indicates that probiotic supplementation positively affects patients, leading to a suppression in cancer symptoms and a shortened disease course. While clinical trials validate the therapeutic benefits of probiotics, their precise mechanism of action remains unclear. This narrative review aims to provide a comprehensive overview of the present landscape of probiotics in the management of lung cancer.

Galectin-3 levels in children with cystic fibrosis

Cystic fibrosis (CF) is a multisystemic disease in which airway obstruction, infection, and inflammation play a critical role in the pathogenesis and progression of CF lung disease. The carbohydrate-binding protein Galectin-3 is increased in several inflammatory and fibrotic diseases and has recently been forwarded as a biomarker in these diseases. We aimed to define the role of serum Galectin-3 in children with CF by comparison with healthy subjects. This is a cross-sectional, case-control study. 143 CF and 30 healthy subjects were enrolled in the study. Peripheral blood and sputum concentrations of Galectins-3, interleukin (IL)-17A, IL-8, and neutrophil elastase (NE) were determined with commercial ELISA kits. There was no significant difference between the groups in age and gender (p = 0.592, p = 0.613, respectively). Serum Galectin-3 and NE concentrations were higher in the patient group than in healthy controls (p = 0.002, p < 0.001, respectively). There were no significant differences between groups according to IL-17A and IL-8 concentrations. Serum Galectin-3 was correlated with age (r = 0.289, p < 0.001) and body mass index (BMI) (r = 0.493, p < 0.001) in children with CF. Sputum Galectin-3 levels are negatively correlated with percent predictive forced expiratory volume in 1 s (FEV1) (r =  - 0.297, p = 0.029), FEV1 z-score, (r =  - 0.316, p = 0.020), percent predictive forced vital capacity (FVC) (r =  - 0.347, p = 0.010), and FVC z-score (r =  - 0.373, p = 0.006).   Conclusion: The study shows that serum Galectin-3 levels increased in clinically stable CF patients, and serum Galectin-3 response may depend on age, gender, and BMI. The sputum Galectin-3 was found to be negatively correlated with patients' lung functions. What is known: • Galectin-3 is a key regulator of chronic inflammation in the lung, liver, kidney, and tumor microenvironment. What is new: • Children with cystic fibrosis (CF) have higher serum Galectin-3 concentrations than healthy children. • Serum Galectin-3 expression influenced by age, BMI, and gender in children with CF.

Putting bicarbonate on the spot: pharmacological insights for CFTR correction in the airway epithelium

Introduction: Cystic fibrosis (CF) is caused by defective Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) proteins. CFTR controls chloride (Cl-) and bicarbonate (HCO3 -) transport into the Airway Surface Liquid (ASL). We investigated the impact of F508del-CFTR correction on HCO3 - secretion by studying transepithelial HCO3 - fluxes. Methods: HCO3 - secretion was measured by pH-stat technique in primary human respiratory epithelial cells from healthy subjects (WT) and people with CF (pwCF) carrying at least one F508del variant. Its changes after CFTR modulation by the triple combination VX445/661/770 and in the context of TNF-α+IL-17 induced inflammation were correlated to ASL pH and transcriptional levels of CFTR and other HCO3 - transporters of airway epithelia such as SLC26A4 (Pendrin), SLC26A9 and NBCe1. Results: CFTR-mediated HCO3 - secretion was not detected in F508del primary human respiratory epithelial cells. It was rescued up to ∼ 80% of the WT level by VX-445/661/770. In contrast, TNF-α+IL-17 normalized transepithelial HCO3 - transport and increased ASL pH. This was related to an increase in SLC26A4 and CFTR transcript levels. VX-445/661/770 induced an increase in pH only in the context of inflammation. Effects on HCO3 - transport were not different between F508del homozygous and F508del compound heterozygous CF airway epithelia. Conclusion: Our studies show that correction of F508del-CFTR HCO3 - is not sufficient to buffer acidic ASL and inflammation is a key regulator of HCO3 - secretion in CF airways. Prediction of the response to CFTR modulators by theratyping should take into account airway inflammation.

Manifestation and staging of arthropathy in cystic fibrosis. Defining different stages of cystic fibrosis arthropathy using ultrasound imaging and clinical scoring

BACKGROUND

The true prevalence of cystic fibrosis arthropathy (CFA) remains unclear and may be significantly higher than previously reported. In recent studies, joint symptoms have been reported in up to 30% of adults with CF. This underlines the importance of CFA as a rising and clinically relevant co-morbidity. A clear definition of CFA is yet missing and its pathogenesis remains unclear. We investigated the clinical manifestation of CFA particularly via ultrasound (US) examination to define and implement a staging for clinical assessment.

METHODS

In a prospective cohort study between March 2018 and February 2020 a total of 98 consecutively recruited, adult cystic fibrosis (CF) patients underwent joint-US examination according to a newly developed ultrasound score (US-CFA). A clinical assessment including rheumatological scores (DAS28, HAQ) has been conducted as well as a specially designed questionnaire. Investigation on clinical and microbiological data, as well as a comprehensive laboratory analysis, were carried out. Cluster analysis has been performed to detect patterns defining different CFA stages based on disease activity.

RESULTS

US imaging has shown a considerable incidence of mild to moderate effusion as sign of joint inflammation/(teno-)synovitis. K-means clustering was used to distinguish 3 different stages of CFA based on the intensity of the detected effusion. These stages showed a significant association with disease activity (DAS28, p = 0.0004) as well as with patient-reported symptoms such as total weeks of CFA per year (p = 0.004), acute CFA (p = 0.015), chronic CFA (p = 0.016), disease burden (p = 0.04). Based on the US-CFA, 16% of patients suffered from severe CFA (II), 51% from intermediate CFA (I) and 33% did not present detectable arthritis. Positive serology for Chlamydophilia pneumoniae (IgA, IgG) and Chlamydia trachomatis (IgA, IgG) significantly correlated with the US-CFA.

CONCLUSIONS

The results of this study show that a definition and categorization for the clinical manifestation of CFA can be described through US examination, which is able to detect disease activity concordant with the DAS28 as a validated clinical score on arthritis. Defining these stages will lead to a better understanding of the clinical phenotype of the disease and will optimize diagnosis, therapy and research on CFA in the future.

Lung Inflammatory Genes in Cystic Fibrosis and Their Relevance to Cystic Fibrosis Transmembrane Conductance Regulator Modulator Therapies

Cystic fibrosis (CF) is a monogenic syndrome determined by over 2000 mutations in the CF Transmembrane Conductance Regulator (CFTR) gene harbored on chromosome 7. In people with CF (PWCF), lung disease is the major determinant of morbidity and mortality and is characterized by a clinical phenotype which differs in the presence of equal mutational assets, indicating that genetic and environmental modifiers play an important role in this variability. Airway inflammation determines the pathophysiology of CF lung disease (CFLD) both at its onset and progression. In this narrative review, we aim to depict the inflammatory process in CF lung, with a particular emphasis on those genetic polymorphisms that could modify the clinical outcome of the respiratory disease in PWCF. The natural history of CF has been changed since the introduction of CFTR modulator therapies in the clinical arena. However, also in this case, there is a patient-to-patient variable response. We provide an overview on inflammatory/immunity gene variants that affect CFLD severity and an appraisal of the effects of CFTR modulator therapies on the inflammatory process in lung disease and how this knowledge may advance the optimization of the management of PWCF.

Pulmonary exacerbations in early cystic fibrosis lung disease are marked by strong modulation of CD3 and PD-1 on luminal T cells

Background

In chronic cystic fibrosis (CF) lung disease, neutrophilic inflammation and T-cell inhibition occur concomitantly, partly due to neutrophil-mediated release of the T-cell inhibitory enzyme Arg1. However, the onset of this tonic inhibition of T cells, and the impact of pulmonary exacerbations (PEs) on this process, remain unknown.

Methods

Children with CF aged 0-5 years were enrolled in a longitudinal, single-center cohort study. Blood (n = 35) and bronchoalveolar lavage (BAL) fluid (n = 18) were collected at stable outpatient clinic visits or inpatient PE hospitalizations and analyzed by flow cytometry (for immune cell presence and phenotype) and 20-plex chemiluminescence assay (for immune mediators). Patients were categorized by PE history into (i) no prior PE, (ii) past history of PE prior to stable visit, or (iii) current PE.

Results

PEs were associated with increased concentration of both pro- and anti-inflammatory mediators in BAL, and increased neutrophil frequency and G-CSF in circulation. PE BAL samples showed a trend toward an increased frequency of hyperexocytic "GRIM" neutrophils, which we previously identified in chronic CF. Interestingly, expression levels of the T-cell receptor associated molecule CD3 and of the inhibitory programmed death-1 (PD-1) receptor were respectively decreased and increased on T cells from BAL compared to blood in all patients. When categorized by PE status, CD3 and PD-1 expression on blood T cells did not differ among patients, while CD3 expression was decreased, and PD-1 expression was increased on BAL T cells from patients with current PE.

Conclusions

Our findings suggest that airway T cells are engaged during early-life PEs, prior to the onset of chronic neutrophilic inflammation in CF. In addition, increased blood neutrophil frequency and a trend toward increased BAL frequency of hyperexocytic neutrophils suggest that childhood PEs may progressively shift the balance of CF airway immunity towards neutrophil dominance.

Defeating a superbug: A breakthrough in vaccine design against multidrug-resistant Pseudomonas aeruginosa using reverse vaccinology

BACKGROUND

Multidrug-resistant Pseudomonas aeruginosa has become a major cause of severe infections. Due to the lack of approved vaccines, this study has presented putative vaccine candidates against it.

METHODS

P. aeruginosa 24Pae112 as a reference strain was retrieved from GenBank database. The surface-exposed, antigenic, non-allergenic, and non-homologous human proteins were selected. The conserved domains of selected proteins were evaluated, and the prevalence of proteins was assessed among 395 genomes. Next, linear and conformational B-cell epitopes, and human MHC II binding sites were determined. Finally, five conserved and highly antigenic B-cell epitopes from OMPs were implanted on the three platforms as multi-epitope vaccines, including FliC, the bacteriophage T7 tail, and the cell wall-associated transporter proteins. The immunoreactivity was investigated using molecular docking and immune simulation. Furthermore, molecular dynamics simulation was done to refine the chimeric cell-wall-associated transporter-TLR4 complex as the best interaction.

RESULTS

Among 6494 total proteins of P. aeruginosa 24Pae112, 16 proteins (seven OMPs and nine secreted) were ideal according to the defined criteria. These proteins had a molecular weight of 110 kDa and were prevalent in ≥ 75% of P. aeruginosa genomes. Among the presented multi-epitope vaccines, the chimeric cell-wall-associated transporter had the strongest interaction with TLR4. Moreover, the immune simulation response revealed that the bacteriophage T7 tail chimeric protein had the strongest ability to stimulate the immune system. In addition, molecular docking and molecular dynamic simulation indicated the proper and stable interactions between the chimeric cell-wall-associated transporter and TLR4.

CONCLUSION

This study proposed 16 shortlisted proteins as promising immunogenic targets. Two novel platforms (e.g. cell-wall-associated transporter and bacteriophage T7 tail proteins) for designing of multi-epitope vaccines (MEVs), showed the better performance compared to FliC. In our future studies, these two MEVs will receive more scrutiny to evaluate their immunoreactivity.

Basic, translational and clinical aspects of bronchiectasis in adults

Bronchiectasis is a common progressive respiratory disease with recognisable radiological abnormalities and a clinical syndrome of cough, sputum production and recurrent respiratory infections. Inflammatory cell infiltration into the lung, in particular neutrophils, is central to the pathophysiology of bronchiectasis. Herein we explore the roles and relationships between infection, inflammation and mucociliary clearance dysfunction in the establishment and progression of bronchiectasis. Microbial and host-mediated damage are important processes underpinning bronchiectasis and the relative contribution of proteases, cytokines and inflammatory mediators to the propagation of inflammation is presented. We also discuss the emerging concept of inflammatory endotypes, defined by the presence of neutrophilic and eosinophilic inflammation, and explore the role of inflammation as a treatable trait. Current treatment for bronchiectasis focuses on treatment of underlying causes, enhancing mucociliary clearance, controlling infection and preventing and treating complications. Data on airway clearance approaches via exercise and mucoactive drugs, pharmacotherapy with macrolides to decrease exacerbations and the usefulness of inhaled antibiotics and bronchodilators are discussed, finishing with a look to the future where new therapies targeting host-mediated immune dysfunction hold promise.

Inflammation as a Regulator of the Airway Surface Liquid pH in Cystic Fibrosis

The airway surface liquid (ASL) is a thin sheet of fluid that covers the luminal aspect of the airway epithelium. The ASL is a site of several first-line host defenses, and its composition is a key factor that determines respiratory fitness. Specifically, the acid-base balance of ASL has a major influence on the vital respiratory defense processes of mucociliary clearance and antimicrobial peptide activity against inhaled pathogens. In the inherited disorder cystic fibrosis (CF), loss of cystic fibrosis transmembrane conductance regulator (CFTR) anion channel function reduces HCO3- secretion, lowers the pH of ASL (pHASL), and impairs host defenses. These abnormalities initiate a pathologic process whose hallmarks are chronic infection, inflammation, mucus obstruction, and bronchiectasis. Inflammation is particularly relevant as it develops early in CF and persists despite highly effective CFTR modulator therapy. Recent studies show that inflammation may alter HCO3- and H+ secretion across the airway epithelia and thus regulate pHASL. Moreover, inflammation may enhance the restoration of CFTR channel function in CF epithelia exposed to clinically approved modulators. This review focuses on the complex relationships between acid-base secretion, airway inflammation, pHASL regulation, and therapeutic responses to CFTR modulators. These factors have important implications for defining optimal ways of tackling CF airway inflammation in the post-modulator era.

The Airway Microbiome-IL-17 Axis: a Critical Regulator of Chronic Inflammatory Disease

The respiratory tract is home to a diverse microbial community whose influence on local and systemic immune responses is only beginning to be appreciated. Increasing reports have linked changes in this microbiome to a range of pulmonary and extrapulmonary disorders, including asthma, chronic obstructive pulmonary disease and rheumatoid arthritis. Central to many of these findings is the role of IL-17-type immunity as an important driver of inflammation. Despite the crucial role played by IL-17-mediated immune responses in protection against infection, overt Th17 cell responses have been implicated in the pathogenesis of several chronic inflammatory diseases. However, our knowledge of the influence of bacteria that commonly colonise the respiratory tract on IL-17-driven inflammatory responses remains sparse. In this article, we review the current knowledge on the role of specific members of the airway microbiota in the modulation of IL-17-type immunity and discuss how this line of research may support the testing of susceptible individuals and targeting of inflammation at its earliest stages in the hope of preventing the development of chronic disease.

Coxiella burnetii actively blocks IL-17-induced oxidative stress in macrophages

Coxiella burnetii is a highly infectious pathogen that causes Q fever, a leading cause of culture-negative endocarditis. Coxiella first targets alveolar macrophages and forms a phagolysosome-like compartment called the Coxiella-Containing Vacuole (CCV). Successful host cell infection requires the Type 4B Secretion System (T4BSS), which translocates bacterial effector proteins across the CCV membrane into the host cytoplasm, where they manipulate numerous cell processes. Our prior transcriptional studies revealed that Coxiella T4BSS blocks IL-17 signaling in macrophages. Given that IL-17 is known to protect against pulmonary pathogens, we hypothesize that C. burnetii T4BSS downregulates intracellular IL-17 signaling to evade the host immune response and promote bacterial pathogenesis. Using a stable IL-17 promoter reporter cell line, we confirmed that Coxiella T4BSS blocks IL-17 transcription activation. Assessment of the phosphorylation state of NF-κB, MAPK, and JNK revealed that Coxiella downregulates IL-17 activation of these proteins. Using ACT1 knockdown and IL-17RA or TRAF6 knockout cells, we next determined that IL17RA-ACT1-TRAF6 pathway is essential for the IL-17 bactericidal effect in macrophages. In addition, macrophages stimulated with IL-17 generate higher levels of reactive oxygen species, which is likely connected to the bactericidal effect of IL-17. However, C. burnetii T4SS effector proteins block the IL-17-mediated oxidative stress, suggesting that Coxiella blocks IL-17 signaling to avoid direct killing by the macrophages.

Multi-omic comparisons between CFBE41o- cells stably expressing wild-type CFTR and F508del-mutant CFTR

BACKGROUND

Cystic fibrosis (CF) is characterized by chronic inflammation and excessive cytokines secretion in the lung. Isogenic human CF bronchial epithelial (CFBE41o-) cell lines stably expressing wt-CFTR (WTBE) or F508del mutant (CFBE) are widely used tools in understanding responses to stimuli or drugs and CF pathogenesis in vitro. However, the intrinsic cellular differences in culture are unknown.

METHODS

We performed integrative analyses of these isogenic cells at the protein, mRNA, and chromatin levels in the submerged and air-liquid interface (ALI) conditions to determine cell intrinsic effects of mutant versus complemented CFTR expression.

RESULTS

CFBE and WTBE cells displayed different cytokine secretion patterns, including IL-6, IL-8, CXCL1, CXCL10, and CCL5. The ALI culture dramatically increased cytokine secretion in both cells. Assay for transposase-accessible chromatin using sequencing (ATAC-seq) result showed different chromatin landscapes upon polarization and CFBE cells, compared to WTBE cells, exhibited higher genome-wide chromatin accessibility under both culture methods. At the transcriptome level, differentially expressed genes identified by mRNA sequencing between two cell lines were highly concentrated in immunity-related pathways.

CONCLUSIONS

This multilayered study shows that expression of wild-type CFTR has an epithelial cell intrinsic effect on the cell's epigenome and transcriptome particularly in immunity relevant activities. These data will serve as a resource for the CF community and may serve as epithelial biomarkers for CFTR mRNA therapy.

Long-term exposure to PM2.5 aggravates pulmonary fibrosis and acute lung injury by disrupting Nrf2-mediated antioxidant function

Epidemiological studies have indicated that exposure to ambient air-borne fine particulate matter (PM2.5) is associated with many cardiopulmonary diseases; however, the underlying pathological mechanisms of PM2.5-induced lung injury remain unknown. In this study, we aimed to assess the impact of acute or prolonged exposure to water-insoluble fractions of PM2.5 (PM2.5 particulate) on lung injury and its molecular mechanisms. Balb/c mice were randomly exposed to PM2.5 once (acute exposure) or once every three days for a total of 6 times (prolonged exposure). Lung, BALF and blood samples were collected, and pulmonary pathophysiological alterations were analyzed. Nrf2 knockout mice were adapted to assess the involvement of Nrf2 in lung injury, and transcriptomic analysis was performed to delineate the mechanisms. Through transcriptomic analysis and validation of Nrf2 knockout mice, we found that acute exposure to PM2.5 insoluble particulates induced neutrophil infiltration-mediated airway inflammation, whereas prolonged exposure to PM2.5 insoluble particulate triggered lung fibrosis by decreasing the transcriptional activity of Nrf2, which resulted in the downregulated expression of antioxidant-related genes. In response to secondary LPS exposure, prolonged PM2.5 exposure induced more severe lung injury, indicating that prolonged PM2.5 exposure induced Nrf2 inhibition weakened its antioxidative defense capacity against oxidative stress injury, leading to the formation of pulmonary fibrosis and increasing its susceptibility to secondary bacterial infection.

WNK Inhibition Increases Surface Liquid pH and Host Defense in Cystic Fibrosis Airway Epithelia

In cystic fibrosis (CF), reduced HCO3- secretion acidifies the airway surface liquid (ASL), and the acidic pH disrupts host defenses. Thus, understanding the control of ASL pH (pHASL) in CF may help identify novel targets and facilitate therapeutic development. In diverse epithelia, the WNK (with-no-lysine [K]) kinases coordinate HCO3- and Cl- transport, but their functions in airway epithelia are poorly understood. Here, we tested the hypothesis that WNK kinases regulate CF pHASL. In primary cultures of differentiated human airway epithelia, inhibiting WNK kinases acutely increased both CF and non-CF pHASL. This response was HCO3- dependent and involved downstream SPAK/OSR1 (Ste20/SPS1-related proline-alanine-rich protein kinase/oxidative stress responsive 1 kinase). Importantly, WNK inhibition enhanced key host defenses otherwise impaired in CF. Human airway epithelia expressed two WNK isoforms in secretory cells and ionocytes, and knockdown of either WNK1 or WNK2 increased CF pHASL. WNK inhibition decreased Cl- secretion and the response to bumetanide, an NKCC1 (sodium-potassium-chloride cotransporter 1) inhibitor. Surprisingly, bumetanide alone or basolateral Cl- substitution also alkalinized CF pHASL. These data suggest that WNK kinases influence the balance between transepithelial Cl- versus HCO3- secretion. Moreover, reducing basolateral Cl- entry may increase HCO3- secretion and raise pHASL, thereby improving CF host defenses.

IL-17 Cytokines and Chronic Lung Diseases

IL-17 cytokines are expressed by numerous cells (e.g., gamma delta (γδ) T, innate lymphoid (ILC), Th17, epithelial cells). They contribute to the elimination of bacteria through the induction of cytokines and chemokines which mediate the recruitment of inflammatory cells to the site of infection. However, IL-17-driven inflammation also likely promotes the progression of chronic lung diseases, such as chronic obstructive pulmonary disease (COPD), lung cancer, cystic fibrosis, and asthma. In this review, we highlight the role of IL-17 cytokines in chronic lung diseases.

MBL Binding with AhR Controls Th17 Immunity in Silicosis-Associated Lung Inflammation and Fibrosis

Objective

Mannan-binding lectin (MBL), a soluble pattern recognition molecule of the innate immune system, is primarily synthesized in the liver and secreted into the circulation. Low serum level of MBL has been reported to be related to an increased risk of lung diseases. Herein, we aimed to investigate the function of MBL in silicosis-associated pulmonary inflammation.

Methods

Serum collected from silicosis patients was tested for correlation between serum MBL levels and Th17 immunity. In vitro studies were performed to further demonstrated the effect of MBL on Th17 polarization. Silica was intratracheally injected in wild type (WT) or MBL-deficient (MBL^–/–) mice to induce silicosis-associated lung inflammation and fibrosis. Th17 response was evaluated to explore the effect of MBL on silicosis in vivo.

Results

Silicosis patients with high serum MBL levels displayed ameliorative lung function. We demonstrated that serum MBL levels negatively correlated to Th17 cell frequency in silicosis patients. MBL protein markedly reduced expression of IL-17 but enhanced expression of Foxp3 in CD4⁺ T cells in vitro when subjected to Th17 or Treg polarizing conditions, respectively. The presence of MBL during Th17 cell polarization significantly limited aryl hydrocarbon receptor (AhR) expression and suppressed the signal transducer and activator of transcription 3 (STAT3) phosphorylation. Treatment with the AhR antagonist abolished the effect of MBL on Th17 response. Strikingly, MBL directly bound to AhR and affected its nuclear translocation. Furthermore, MBL^–/– mice displayed elevated Th17 cell levels compared with WT mice in response to the silica challenge. The CD4⁺ T lymphocytes from silica-administrated MBL^–/– mice exhibited more AhR expression than the wild-type counterparts.

Conclusion

Our study suggested that MBL limited the Th17 immunity via controlling the AhR/STAT3 pathway, thus providing new insight into silicosis and other inflammatory diseases in patients with MBL deficiency.

Interleukin-17A and interleukin-22 production by conventional and non-conventional lymphocytes in three different end-stage lung diseases

Objectives

The contribution of adaptive vs. innate lymphocytes to IL-17A and IL-22 secretion at the end stage of chronic lung diseases remains largely unexplored. In order to uncover tissue- and disease-specific secretion patterns, we compared production patterns of IL-17A and IL-22 in three different human end-stage lung disease entities.

Methods

Production of IL-17A, IL-22 and associated cytokines was assessed in supernatants of re-stimulated lymphocytes by multiplex assays and multicolour flow cytometry of conventional T cells, iNKT cells, γδ T cells and innate lymphoid cells in bronchial lymph node and lung tissue from patients with emphysema (n = 19), idiopathic pulmonary fibrosis (n = 14) and cystic fibrosis (n = 23), as well as lung donors (n = 17).

Results

We detected secretion of IL-17A and IL-22 by CD4⁺ T cells, CD8⁺ T cells, innate lymphoid cells, γδ T cells and iNKT cells in all end-stage lung disease entities. Our analyses revealed disease-specific contributions of individual lymphocyte subpopulations to cytokine secretion patterns. We furthermore found the high levels of microbial detection in CF samples to associate with a more pronounced IL-17A signature upon antigen-specific and unspecific re-stimulation compared to other disease entities and lung donors.

Conclusion

Our results show that both adaptive and innate lymphocyte populations contribute to IL-17A-dependent pathologies in different end-stage lung disease entities, where they establish an IL-17A-rich microenvironment. Microbial colonisation patterns and cytokine secretion upon microbial re-stimulation suggest that pathogens drive IL-17A secretion patterns in end-stage lung disease.

Immunoglobulin A Mucosal Immunity and Altered Respiratory Epithelium in Cystic Fibrosis

The respiratory epithelium represents the first chemical, immune, and physical barrier against inhaled noxious materials, particularly pathogens in cystic fibrosis. Local mucus thickening, altered mucociliary clearance, and reduced pH due to CFTR protein dysfunction favor bacterial overgrowth and excessive inflammation. We aimed in this review to summarize respiratory mucosal alterations within the epithelium and current knowledge on local immunity linked to immunoglobulin A in patients with cystic fibrosis.

Current evidence on the effect of highly effective CFTR modulation on interleukin-8 in cystic fibrosis

INTRODUCTION

Cystic fibrosis (CF) is a genetically inherited disease, with mortality and morbidity associated with respiratory disease. The inflammatory response in CF is characterized by excessive neutrophil influx to the airways, mainly due to the increased local production and retention of interleukin-8 (IL-8), a potent neutrophil chemoattractant.

AREAS COVERED

We discuss how the chemokine IL-8 dominates the inflammatory profile of the airways in CF lung disease. Cystic fibrosis transmembrane conductance regulator (CFTR) modulator therapies are designed to correct the malfunctioning protein resulting from specific CFTR mutations. This review covers current evidence on the impact of CFTR impairment on levels of IL-8 and outlines the influence of effective CFTR modulation on inflammation in CF with a focus on cytokine production. Review of the literature was carried out using the PUBMED database, Google Scholar, and The Cochrane Library databases, using several appropriate generic terms.

EXPERT OPINION

Therapeutic interventions specifically targeting the defective CFTR protein have improved the outlook for CF. Accumulating studies on the effect of highly effective CFTR modulation on inflammation indicate an impact on IL-8 levels. Further studies are required to increase our knowledge of early onset innate inflammatory dysregulation and on anti-inflammatory mechanisms of CFTR modulators.

Gamma Delta T Cells and Their Involvement in COVID-19 Virus Infections

The global outbreak of the SARS-Cov-2 virus in 2020 has killed millions of people worldwide and forced large parts of the world into lockdowns. While multiple vaccine programs are starting to immunize the global population, there is no direct cure for COVID-19, the disease caused by the SARS-Cov-2 infection. A common symptom in patients is a decrease in T cells, called lymphopenia. It is as of yet unclear what the exact role of T cells are in the immune response to COVID-19. The research so far has mainly focused on the involvement of classical αβ T cells. However, another subset of T cells called γδ T cells could have an important role to play. As part of the innate immune system, γδ T cells respond to inflammation and stressed or infected cells. The γδ T cell subset appears to be particularly affected by lymphopenia in COVID-19 patients and commonly express activation and exhaustion markers. Particularly in children, this subset of T cells seems to be most affected. This is interesting and relevant because γδ T cells are more prominent and active in early life. Their specific involvement in this group of patients could indicate a significant role for γδ T cells in this disease. Furthermore, they seem to be involved in other viral infections and were able to kill SARS infected cells in vitro. γδ T cells can take up, process and present antigens from microbes and human cells. As e.g. tumour-associated antigens are presented by MHC on γδ T cells to classical T-cells, we argue here that it stands to reason that also viral antigens, such as SARS-Cov-2-derived peptides, can be presented in the same way. γδ T cells are already used for medical purposes in oncology and have potential in cancer therapy. As γδ T cells are not necessarily able to distinguish between a transformed and a virally infected cell it could therefore be of great interest to investigate further the relationship between COVID-19 and γδ T cells.

A Markov random field model for network-based differential expression analysis of single-cell RNA-seq data

BACKGROUND

Recent development of single cell sequencing technologies has made it possible to identify genes with different expression (DE) levels at the cell type level between different groups of samples. In this article, we propose to borrow information through known biological networks to increase statistical power to identify differentially expressed genes (DEGs).

RESULTS

We develop MRFscRNAseq, which is based on a Markov random field (MRF) model to appropriately accommodate gene network information as well as dependencies among cell types to identify cell-type specific DEGs. We implement an Expectation-Maximization (EM) algorithm with mean field-like approximation to estimate model parameters and a Gibbs sampler to infer DE status. Simulation study shows that our method has better power to detect cell-type specific DEGs than conventional methods while appropriately controlling type I error rate. The usefulness of our method is demonstrated through its application to study the pathogenesis and biological processes of idiopathic pulmonary fibrosis (IPF) using a single-cell RNA-sequencing (scRNA-seq) data set, which contains 18,150 protein-coding genes across 38 cell types on lung tissues from 32 IPF patients and 28 normal controls.

CONCLUSIONS

The proposed MRF model is implemented in the R package MRFscRNAseq available on GitHub. By utilizing gene-gene and cell-cell networks, our method increases statistical power to detect differentially expressed genes from scRNA-seq data.

The Th17/IL-17 Axis and Kidney Diseases, With Focus on Lupus Nephritis

Systemic lupus erythematosus (SLE) is a disease characterized by dysregulation and hyperreactivity of the immune response at various levels, including hyperactivation of effector cell subtypes, autoantibodies production, immune complex formation, and deposition in tissues. The consequences of hyperreactivity to the self are systemic and local inflammation and tissue damage in multiple organs. Lupus nephritis (LN) is one of the most worrying manifestations of SLE, and most patients have this involvement at some point in the course of the disease. Among the effector cells involved, the Th17, a subtype of T helper cells (CD4+), has shown significant hyperactivation and participates in kidney damage and many other organs. Th17 cells have IL-17A and IL-17F as main cytokines with receptors expressed in most renal cells, being involved in the activation of many proinflammatory and profibrotic pathways. The Th17/IL-17 axis promotes and maintains repetitive tissue damage and maladaptive repair; leading to fibrosis, loss of organ architecture and function. In the podocytes, the Th17/IL-17 axis effects include changes of the cytoskeleton with increased motility, decreased expression of health proteins, increased oxidative stress, and activation of the inflammasome and caspases resulting in podocytes apoptosis. In renal tubular epithelial cells, the Th17/IL-17 axis promotes the activation of profibrotic pathways such as increased TGF-β expression and epithelial-mesenchymal transition (EMT) with consequent increase of extracellular matrix proteins. In addition, the IL-17 promotes a proinflammatory environment by stimulating the synthesis of inflammatory cytokines by intrinsic renal cells and immune cells, and the synthesis of growth factors and chemokines, which together result in granulopoiesis/myelopoiesis, and further recruitment of immune cells to the kidney. The purpose of this work is to present the prognostic and immunopathologic role of the Th17/IL-17 axis in Kidney diseases, with a special focus on LN, including its exploration as a potential immunotherapeutic target in this complication.

Anti-Inflammatory and Anti-Oxidant Effect of Dimethyl Fumarate in Cystic Fibrosis Bronchial Epithelial Cells

Cystic Fibrosis (CF) is caused by mutations on the CF transmembrane conductance regulator (CFTR) gene and is associated with chronic infection and inflammation. Recently, it has been demonstrated that LPS-induced CFTR dysfunction in airway epithelial cells is due to an early oxidative stress. Dimethyl fumarate (DMF) is an approved anti-inflammatory and anti-oxidant drug for auto-immune and inflammatory diseases, but its role in the CF has never been investigated. In this study, we examined the effect of DMF on CF-related cytokines expression, ROS measurements and CFTR channel function. We found that DMF reduced the inflammatory response to LPS stimulation in both CF and non-CF bronchial epithelial cells, both as co-treatment and therapy, and restored LPS-mediated decrease of Trikafta™-mediated CFTR function in CF cells bearing the most common mutation, c.1521_1523delCTT (F508del). DMF also inhibited the inflammatory response induced by IL-1β/H₂O₂ and IL-1β/TNFα, mimicking the inflammatory status of CF patients. Finally, we also demonstrated that DMF exhibited an anti-oxidant effect on CF cells after different inflammatory stimulations. Since DMF is an approved drug, it could be further investigated as a novel anti-inflammatory molecule to ameliorate lung inflammation in CF and improve the CFTR modulators efficacy.

Inflammatory cytokines TNF-α and IL-17 enhance the efficacy of cystic fibrosis transmembrane conductance regulator modulators

Without cystic fibrosis transmembrane conductance regulator-mediated (CFTR-mediated) HCO3- secretion, airway epithelia of newborns with cystic fibrosis (CF) produce an abnormally acidic airway surface liquid (ASL), and the decreased pH impairs respiratory host defenses. However, within a few months of birth, ASL pH increases to match that in non-CF airways. Although the physiological basis for the increase is unknown, this time course matches the development of inflammation in CF airways. To learn whether inflammation alters CF ASL pH, we treated CF epithelia with TNF-α and IL-17 (TNF-α+IL-17), 2 inflammatory cytokines that are elevated in CF airways. TNF-α+IL-17 markedly increased ASL pH by upregulating pendrin, an apical Cl-/HCO3- exchanger. Moreover, when CF epithelia were exposed to TNF-α+IL-17, clinically approved CFTR modulators further alkalinized ASL pH. As predicted by these results, in vivo data revealed a positive correlation between airway inflammation and CFTR modulator-induced improvement in lung function. These findings suggest that inflammation is a key regulator of HCO3- secretion in CF airways. Thus, they explain earlier observations that ASL pH increases after birth and indicate that, for similar levels of inflammation, the pH of CF ASL is abnormally acidic. These results also suggest that a non-cell-autonomous mechanism, airway inflammation, is an important determinant of the response to CFTR modulators.

Anti-Inflammatory Influences of Cystic Fibrosis Transmembrane Conductance Regulator Drugs on Lung Inflammation in Cystic Fibrosis

Cystic fibrosis (CF) is caused by a defect in the cystic fibrosis transmembrane conductance regulator protein (CFTR) which instigates a myriad of respiratory complications including increased vulnerability to lung infections and lung inflammation. The extensive influx of pro-inflammatory cells and production of mediators into the CF lung leading to lung tissue damage and increased susceptibility to microbial infections, creates a highly inflammatory environment. The CF inflammation is particularly driven by neutrophil infiltration, through the IL-23/17 pathway, and function, through NE, NETosis, and NLRP3-inflammasome formation. Better understanding of these pathways may uncover untapped therapeutic targets, potentially reducing disease burden experienced by CF patients. This review outlines the dysregulated lung inflammatory response in CF, explores the current understanding of CFTR modulators on lung inflammation, and provides context for their potential use as therapeutics for CF. Finally, we discuss the determinants that need to be taken into consideration to understand the exaggerated inflammatory response in the CF lung.

Pathophysiology of Bronchiectasis

Bronchiectasis is a complex, heterogeneous disorder defined by both a radiological abnormality of permanent bronchial dilatation and a clinical syndrome. There are multiple underlying causes including severe infections, mycobacterial disease, autoimmune conditions, hypersensitivity disorders, and genetic conditions. The pathophysiology of disease is understood in terms of interdependent concepts of chronic infection, inflammation, impaired mucociliary clearance, and structural lung damage. Neutrophilic inflammation is characteristic of the disease, with elevated levels of harmful proteases such as neutrophil elastase associated with worse outcomes. Recent data show that neutrophil extracellular trap formation may be the key mechanism leading to protease release and severe bronchiectasis. Despite the dominant of neutrophilic disease, eosinophilic subtypes are recognized and may require specific treatments. Neutrophilic inflammation is associated with elevated bacterial loads and chronic infection with organisms such as Pseudomonas aeruginosa. Loss of diversity of the normal lung microbiota and dominance of proteobacteria such as Pseudomonas and Haemophilus are features of severe bronchiectasis and link to poor outcomes. Ciliary dysfunction is also a key feature, exemplified by the rare genetic syndrome of primary ciliary dyskinesia. Mucus symptoms arise through goblet cell hyperplasia and metaplasia and reduced ciliary function through dyskinesia and loss of ciliated cells. The contribution of chronic inflammation, infection, and mucus obstruction leads to progressive structural lung damage. The heterogeneity of the disease is the most challenging aspect of management. An understanding of the pathophysiology of disease and their biomarkers can help to guide personalized medicine approaches utilizing the concept of "treatable traits."

IL-17A from innate and adaptive lymphocytes contributes to inflammation and damage in cystic fibrosis lung disease

BACKGROUND

Elevated levels of interleukin (IL)-17A were detected in the airways of patients with cystic fibrosis (CF), but its cellular sources and role in the pathogenesis of CF lung disease remain poorly understood. The aim of this study was to determine the sources of IL-17A and its role in airway inflammation and lung damage in CF.

METHODS

We performed flow cytometry to identify IL-17A-producing cells in lungs and peripheral blood from CF patients and β-epithelial Na⁺ channel transgenic (Scnn1b-Tg) mice with CF-like lung disease, and determined the effects of genetic deletion of Il17a and Rag1 on the pulmonary phenotype of Scnn1b-Tg mice.

RESULTS

T-helper 17 cells, CD3⁺CD8⁺ T-cells, γδ T-cells, invariant natural killer T-cells and innate lymphoid cells contribute to IL-17A secretion in lung tissue, lymph nodes and peripheral blood of patients with CF. Scnn1b-Tg mice displayed increased pulmonary expression of Il17a and elevated IL-17A-producing innate and adaptive lymphocytes with a major contribution by γδ T-cells. Lack of IL-17A, but not the recombination activating protein RAG1, reduced neutrophilic airway inflammation in Scnn1b-Tg mice. Genetic deletion of Il17a or Rag1 had no effect on mucus obstruction, but reduced structural lung damage and revealed an IL-17A-dependent macrophage activation in Scnn1b-Tg mice.

CONCLUSIONS

We identify innate and adaptive sources of IL-17A in CF lung disease. Our data demonstrate that IL-17A contributes to airway neutrophilia, macrophage activation and structural lung damage in CF-like lung disease in mice. These results suggest IL-17A as a novel target for anti-inflammatory therapy of CF lung disease.

Pseudomonas aeruginosa infection, but not mono or dual-combination CFTR modulator therapy affects circulating regulatory T cells in an adult population with cystic fibrosis

BACKGROUND

Chronic infection and an exaggerated inflammatory response are key drivers of the pathogenesis of cystic fibrosis (CF), especially CF lung disease. An imbalance of pro- and anti-inflammatory mediators, including dysregulated Th2/Th17 cells and impairment of regulatory T cells (Tregs), maintain CF inflammation. CF transmembrane conductance regulator (CFTR) modulator therapy might influence these immune cell abnormalities.

METHODS

Peripheral blood mononuclear cells and serum samples were collected from 108 patients with CF (PWCF) and 40 patients with non-CF bronchiectasis. Samples were analysed for peripheral blood lymphocytes subsets (Tregs; Th1-, Th1/17-, Th17- and Th2-effector cells) and systemic T helper cell-associated cytokines (interleukin [IL]-5, IL-13, IL-2, IL-6, IL-9, IL-10, IL-17A, IL-17F, IL-4, IL-22, interferon-γ, tumour necrosis factor-α) using flow cytometry.

RESULTS

51% of PWCF received CFTR modulators (ivacaftor, ivacaftor/ lumacaftor or tezacaftor/ ivacaftor). There were no differences in proportions of analysed T cell subsets or cytokines between PWCF who were versus were not receiving CFTR modulators. Additional analysis revealed lower percentages of Tregs in PWCF and chronic pulmonary Pseudomonas aeruginosa infection; this difference was also present in PWCF treated with CFTR modulators. Patients with non-CF bronchiectasis tended to have higher percentages of Th2- and Th17-cells and higher levels of peripheral cytokines versus PWCF.

CONCLUSIONS

Chronic P. aeruginosa lung infection appears to impair Tregs in PWCF (independent of CFTR modulator therapy) but not those with non-CF bronchiectasis. Moreover, our data showed no statistically significant differences in major subsets of peripheral lymphocytes and cytokines among PWCF who were versus were not receiving CFTR modulators.

Antimicrobial Resistance in Common Respiratory Pathogens of Chronic Bronchiectasis Patients: A Literature Review

Non-cystic fibrosis bronchiectasis is a chronic disorder in which immune system dysregulation and impaired airway clearance cause mucus accumulation and consequent increased susceptibility to lung infections. The presence of pathogens in the lower respiratory tract causes a vicious circle resulting in impaired mucociliary function, bronchial inflammation, and progressive lung injury. In current guidelines, antibiotic therapy has a key role in bronchiectasis management to treat acute exacerbations and chronic infection and to eradicate bacterial colonization. Contrastingly, antimicrobial resistance, with the risk of multidrug-resistant pathogen development, causes nowadays great concern. The aim of this literature review was to assess the role of antibiotic therapy in bronchiectasis patient management and possible concerns regarding antimicrobial resistance based on current evidence. The authors of this review stress the need to expand research regarding bronchiectasis with the aim to assess measures to reduce the rate of antimicrobial resistance worldwide.

Development of a Chimeric Vaccine Against Pseudomonas aeruginosa Based on the Th17-Stimulating Epitopes of PcrV and AmpC

Pulmonary infection caused by Pseudomonas aeruginosa (PA) has created an urgent need for an efficient vaccine, but the protection induced by current candidates is limited, partially because of the high variability of the PA genome. Antigens targeting pulmonary Th17 responses are able to provide antibody-independent and broad-spectrum protection; however, little information about Th17-stimulating antigens in PA is available. Herein, we identified two novel PA antigens that effectively induce Th17-dependent protection, namely, PcrV (PA1706) and AmpC (PA4110). Compared to intramuscular immunization, intranasal immunization enhanced the protection of rePcrV due to activation of a Th17 response. The Th17-stimulating epitopes of PcrV and AmpC were identified, and the recombinant protein PVAC was designed and generated by combining these Th17-stimulating epitopes. PVAC was successfully produced in soluble form and elicited broad protective immunity against PA. Our results provide an alternative strategy for the development of Th17-based vaccines against PA and other pathogens.

The Potential Causes of Cystic Fibrosis-Related Diabetes

Cystic fibrosis (CF) is a genetic disease caused by mutations in the cystic fibrosis transmembrane conductance regulator gene (CFTR). Cystic fibrosis-related diabetes (CFRD) is the most common comorbidity, affecting more than 50% of adult CF patients. Despite this high prevalence, the etiology of CFRD remains incompletely understood. Studies in young CF children show pancreatic islet disorganization, abnormal glucose tolerance, and delayed first-phase insulin secretion suggesting that islet dysfunction is an early feature of CF. Since insulin-producing pancreatic β-cells express very low levels of CFTR, CFRD likely results from β-cell extrinsic factors. In the vicinity of β-cells, CFTR is expressed in both the exocrine pancreas and the immune system. In the exocrine pancreas, CFTR mutations lead to the obstruction of the pancreatic ductal canal, inflammation, and immune cell infiltration, ultimately causing the destruction of the exocrine pancreas and remodeling of islets. Both inflammation and ductal cells have a direct effect on insulin secretion and could participate in CFRD development. CFTR mutations are also associated with inflammatory responses and excessive cytokine production by various immune cells, which infiltrate the pancreas and exert a negative impact on insulin secretion, causing dysregulation of glucose homeostasis in CF adults. In addition, the function of macrophages in shaping pancreatic islet development may be impaired by CFTR mutations, further contributing to the pancreatic islet structural defects as well as impaired first-phase insulin secretion observed in very young children. This review discusses the different factors that may contribute to CFRD.

Microbiome dysbiosis in lung cancer: from composition to therapy

The correlations between microbiota dysbiosis and cancer have gained extensive attention and been widely explored. As a leading cancer diagnosis worldwide, lung cancer poses a great threat to human health. The healthy human lungs are consistently exposed to external environment and harbor a specific pattern of microbiota, sharing many key pathological and physiological characteristics with the intestinal tract. Although previous findings uncovered the critical roles of microbiota in tumorigenesis and response to anticancer therapy, most of them were focused on the intestinal microbiota rather than lung microbiota. Notably, the considerable functions of microbiota in maintaining lung homeostasis should not be neglected as the microbiome dysbiosis may promote tumor development and progression through production of cytokines and toxins and multiple other pathways. Despite the fact that increasing studies have revealed the effect of microbiome on the induction of lung cancer and different disease status, the underlying mechanisms and potential therapeutic strategies remained unclear. Herein, we summarized the recent progresses about microbiome in lung cancer and further discussed the role of microbial communities in promoting lung cancer progression and the current status of therapeutic approaches targeting microbiome to alleviate and even cure lung cancer.

New Therapeutic Approaches in Cystic Fibrosis

Cystic fibrosis (CF) is a hereditary, multisystemic disease caused by different mutations in the CFTR gene encoding CF transmembrane conductance regulator. CF is mainly characterized by pulmonary dysfunction as a result of deterioration in the mucociliary clearance and anion transport of airways. Mortality is mostly caused by bronchiectasis, bronchiole obstruction, and progressive respiratory dysfunction in the early years of life. Over the last decade, new therapeutic strategies rather than symptomatic treatment have been proposed, such as the small molecule approach, ion channel therapy, and pulmonary gene therapy. Due to considerable progress in the treatment options, CF has become an adult disease rather than a pediatric disease in recent years. Pulmonary gene therapy has gained special attention due to its mutation type independent aspect, therefore being applicable to all CF patients. On the other hand, the major obstacle for CF treatment is to predict the drug response of patients due to genetic complexity and heterogeneity. The advancement of 3D culture systems has made it possible to extrapolate the disease modeling and individual drug response in vitro by producing mini adult organs called "organoids" obtained from rectal cell biopsies. In this review, we summarize the advances in the novel therapeutic approaches, clinical interventions, and precision medicine concept for CF.

Myeloid arginase-1 controls excessive inflammation and modulates T cell responses in Pseudomonas aeruginosa pneumonia

Regulatory properties of macrophages associated with alternative activation serve to limit the exaggerated inflammatory response during pneumonia caused by Pseudomonas aeruginosa infection. Arginase-1 is an important effector of these macrophages believed to play an essential role in decreasing injury and promoting repair. We investigated the role of arginase-1 in the control of inflammatory immune responses to P. aeruginosa pneumonia in mice that exhibit different immunologic phenotypes. C57BL/6 mice with conditional knockout of the arginase-1 (Arg1) gene from myeloid cells (Arg1^ΔM) or BALB/c mice treated with small molecule inhibitors of arginase were infected intratracheally with P. aeruginosa. Weight loss, mortality, bacterial clearance, and lung injury were assessed and compared, as were the characterization of immune cell populations over time post-infection. Myeloid arginase-1 deletion resulted in greater morbidity along with more severe inflammatory responses compared to littermate control mice. Arg1^ΔM mice had greater numbers of neutrophils, macrophages, and lymphocytes in their airways and lymph nodes compared to littermate controls. Additionally, Arg1^ΔM mice recovered from inflammatory lung injury at a significantly slower rate. Conversely, treatment of BALB/c mice with the arginase inhibitor S-(2-boronoethyl)-l-cysteine hydrochloride (BEC) did not change morbidity as defined by weight loss, but mice at day 10 post-infection treated with BEC had gained significantly more weight back than controls. Neutrophil and macrophage infiltration were similar between groups in the lung parenchyma, and neutrophil migration into the airways was reduced by BEC treatment. Differences seem to lie in the impact on T cell subset disposition. Arg1^ΔM mice had increased total CD4+ T cell expansion in the lymph nodes, and increased T cell activation, IFNγ production, and IL-17 production in the lymph nodes, lung interstitium, and airways, while treatment with BEC had no impact on T cell activation or IL-17 production, but reduced the number of T cells producing IFNγ in the lungs. Lung injury scores were increased in the Arg1^ΔM mice, but no differences were observed in the mice treated with pharmacologic arginase inhibitors. Overall, myeloid arginase production was demonstrated to be essential for control of damaging inflammatory responses associated with P. aeruginosa pneumonia in C57BL/6 mice, in contrast to a protective effect in the Th2-dominant BALB/c mice when arginase activity is globally inhibited.

Bile Acid Signal Molecules Associate Temporally with Respiratory Inflammation and Microbiome Signatures in Clinically Stable Cystic Fibrosis Patients

Cystic fibrosis (CF) is a congenital disorder resulting in a multisystemic impairment in ion homeostasis. The subsequent alteration of electrochemical gradients severely compromises the function of the airway epithelia. These functional changes are accompanied by recurrent cycles of inflammation–infection that progressively lead to pulmonary insufficiency. Recent developments have pointed to the existence of a gut–lung axis connection, which may modulate the progression of lung disease. Molecular signals governing the interplay between these two organs are therefore candidate molecules requiring further clinical evaluation as potential biomarkers. We demonstrate a temporal association between bile acid (BA) metabolites and inflammatory markers in bronchoalveolar lavage fluid (BALF) from clinically stable children with CF. By modelling the BALF-associated microbial communities, we demonstrate that profiles enriched in operational taxonomic units assigned to supraglottic taxa and opportunistic pathogens are closely associated with inflammatory biomarkers. Applying regression analyses, we also confirmed a linear link between BA concentration and pathogen abundance in BALF. Analysis of the time series data suggests that the continuous detection of BAs in BALF is linked to differential ecological succession trajectories of the lung microbiota. Our data provide further evidence supporting a role for BAs in the early pathogenesis and progression of CF lung disease.

Dysregulated signalling pathways in innate immune cells with cystic fibrosis mutations

Cystic fibrosis (CF) is one of the most common life-limiting recessive genetic disorders in Caucasians, caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR). CF is a multi-organ disease that involves the lungs, pancreas, sweat glands, digestive and reproductive systems and several other tissues. This debilitating condition is associated with recurrent lower respiratory tract bacterial and viral infections, as well as inflammatory complications that may eventually lead to pulmonary failure. Immune cells play a crucial role in protecting the organs against opportunistic infections and also in the regulation of tissue homeostasis. Innate immune cells are generally affected by CFTR mutations in patients with CF, leading to dysregulation of several cellular signalling pathways that are in continuous use by these cells to elicit a proper immune response. There is substantial evidence to show that airway epithelial cells, neutrophils, monocytes and macrophages all contribute to the pathogenesis of CF, underlying the importance of the CFTR in innate immune responses. The goal of this review is to put into context the important role of the CFTR in different innate immune cells and how CFTR dysfunction contributes to the pathogenesis of CF, highlighting several signalling pathways that may be dysregulated in cells with CFTR mutations.

Th17 associated cytokines in sputum samples from patients with cystic fibrosis

Cystic fibrosis (CF) is a genetic disease leading to chronic bacterial airway infection and inflammation. T helper 17 (Th17) cells are identified by their production of interleukin (IL)-17A, which recruit neutrophils to the site of airway infection. IL-23 is an important inducer of IL-17 and IL-22 production. The aim of this study was to study the role of Th17 cells in CF airway infection by measuring the levels of Th17 associated cytokines in sputum from CF patients with or without airway infection and by comparison with non-CF-controls. In a cross-sectional screening study, cytokine levels were measured with a Th17 multiplex cytokine ELISA. Significantly lower levels of IL-17A and IL-23 were found in sputa from infected CF patients. The lowest levels of IL-17A were found in patients chronically infected with P. aeruginosa, which also had the lowest IL-17/IL-22 ratio, while children had a higher ratio. Children also had higher IL-23 levels than adults. IL-1ß and IL-10 were significantly lower in CF sputum compared to controls. Thus, in our study CF patients with chronic infections had a lower production of Th17 associated cytokines in sputum compared with non-infected CF patients and infected patient without CF.

Development of a vaccine against Staphylococcus aureus invasive infections: Evidence based on human immunity, genetics and bacterial evasion mechanisms

Invasive Staphylococcus aureus infections are a leading cause of morbidity and mortality in both hospital and community settings, especially with the widespread emergence of virulent and multi-drug resistant methicillin-resistant S. aureus strains. There is an urgent and unmet clinical need for non-antibiotic immune-based approaches to treat these infections as the increasing antibiotic resistance is creating a serious threat to public health. However, all vaccination attempts aimed at preventing S. aureus invasive infections have failed in human trials, especially all vaccines aimed at generating high titers of opsonic antibodies against S. aureus surface antigens to facilitate antibody-mediated bacterial clearance. In this review, we summarize the data from humans regarding the immune responses that protect against invasive S. aureus infections as well as host genetic factors and bacterial evasion mechanisms, which are important to consider for the future development of effective and successful vaccines and immunotherapies against invasive S. aureus infections in humans. The evidence presented form the basis for a hypothesis that staphylococcal toxins (including superantigens and pore-forming toxins) are important virulence factors, and targeting the neutralization of these toxins are more likely to provide a therapeutic benefit in contrast to prior vaccine attempts to generate antibodies to facilitate opsonophagocytosis.

Relevance between clinical status and exhaled molecules related to neutrophilic inflammation in pediatric cystic fibrosis

INTRODUCTION

Cystic fibrosis (CF) is characterized with chronic inflammation with neutrophil and related cytokines in airway secretions. We aimed to measure the levels of neutrophil related inflammatory markers as nitric oxide, IL-8, IL-17, leukotriene B4 and neutrophil elastase as well as e-cadherin in exhaled breath condensate (EBC), and to determine their relation with clinical findings.

METHODS

We consecutively enrolled cystic fibrosis patients into our clinics between the age of six and eighteen years who could cooperate for exhaled breath condensate to this case-control study (n = 30). The age and sex matched control group (n = 26) was enrolled. Spirometry was performed during the stable period and EBC samples were obtained for measurement of the markers.

RESULTS

The mean age of the subjects enrolled was 12.1(4.2) years and 40% were positive for P.Aeruginosa in sputum. Subjects who had P.Aeruginosa in sputum cultures had significantly lower FEV1, FVC and FEF 25/75 values compared to the ones without P.Aeruginosa (p = 0.002, p = 0.002 and p = 0.005 respectively). EBC neutrophil elastase levels were significantly higher in the CF patients compared to non-CF controls (3.11 ± 4.71 versus 0.90 ± 2.68, p = 0.04). Nitric oxide, IL-17, IL-8, e-cadherin, neutrophil elastase or leukotriene B4 levels in EBC of CF patients were not related to P.Aeruginosa s infection, FEV1 levels or hospital admission in the last year.

CONCLUSION

In our study, neutrophil elastase levels in EBC are higher in CF patients compared to non-CF controls. This is independent of acute infection and is evidence to the persistence of neutrophilic lung injury. However, EBC NO, IL-8, IL-17, e-cadherin, neutrophil elastase and leukotriene B4 levels as inflammatory markers, are not correlated with disease progression or clinical findings.

T Cells in Fibrosis and Fibrotic Diseases

Fibrosis is the extensive deposition of fibrous connective tissue, and it is characterized by the accumulation of collagen and other extracellular matrix (ECM) components. Fibrosis is essential for wound healing and tissue repair in response to a variety of triggers, which include infection, inflammation, autoimmune disorder, degenerative disease, tumor, and injury. Fibrotic remodeling in various diseases, such as liver cirrhosis, pulmonary fibrosis, renal interstitial fibrosis, myocardial infarction, systemic sclerosis (SSc), and graft-versus-host disease (GVHD), can impair organ function, causing high morbidity and mortality. Both innate and adaptive immunity are involved in fibrogenesis. Although the roles of macrophages in fibrogenesis have been studied for many years, the underlying mechanisms concerning the manner in which T cells regulate fibrosis are not completely understood. The T cell receptor (TCR) engages the antigen and shapes the repertoire of antigen-specific T cells. Based on the divergent expression of surface molecules and cell functions, T cells are subdivided into natural killer T (NKT) cells, γδ T cells, CD8⁺ cytotoxic T lymphocytes (CTL), regulatory T (Treg) cells, T follicular regulatory (Tfr) cells, and T helper cells, including Th1, Th2, Th9, Th17, Th22, and T follicular helper (Tfh) cells. In this review, we summarize the pro-fibrotic or anti-fibrotic roles and distinct mechanisms of different T cell subsets. On reviewing the literature, we conclude that the T cell regulations are commonly disease-specific and tissue-specific. Finally, we provide perspectives on microbiota, viral infection, and metabolism, and discuss the current advancements of technologies for identifying novel targets and developing immunotherapies for intervention in fibrosis and fibrotic diseases.

Fibrocyte accumulation in the lungs of cystic fibrosis patients

BACKGROUND

Cystic fibrosis (CF) patients develop severe lung disease including chronic airway infections, neutrophilic inflammation, and progressive fibrotic remodeling in airways. However, cellular and molecular processes that regulate excessive collagen deposition in airways in these patients remain unclear. Fibrocytes are bone marrow (BM)-derived mesenchymal cells that express the hematopoietic cell marker CD45, and mesenchymal cell markers and implicated in collagen deposition in several fibrotic diseases. It is unknown whether fibrocytes accumulate in the lungs of CF patients, so the current study evaluates the presence of fibrocytes in the fibrotic lesions of airways in explanted CF lungs compared to non-CF unused donor lungs (control).

METHODS

We used immunofluorescence staining to determine if fibrocytes accumulate in explanted CF lungs compared to healthy donor lungs. Simultaneously, we evaluated cells collected by bronchoalveolar lavage (BAL) in CF patients using multi-color flow cytometry. Finally, we analyzed transcripts differentially expressed in fibrocytes isolated from the explanted CF lungs compared to control to assess fibrocyte-specific pro-fibrotic gene networks.

RESULTS

Our findings demonstrate fibrocyte accumulation in CF lungs compared to non-CF lungs. Additionally, fibrocytes were detected in the BAL of all CF children. Transcriptomic analysis of fibrocytes identified dysregulated genes associated with fibrotic remodeling in CF lungs.

CONCLUSIONS

With significantly increased fibrocytes that show increased expression of pro-fibrotic gene transcripts compared to control, our findings suggest an intervention for fibrotic remodeling as a potential therapeutic target in CF.

Early Surgical Management of Thermal Airway Injury: A Case Series

Inhalation injury is an independent risk factor in burn mortality, imparting a 20% increased risk of death. Yet there is little information on the natural history, functional outcome, or pathophysiology of thermal injury to the laryngotracheal complex, limiting treatment progress. This paper demonstrates a case series (n = 3) of significant thermal airway injuries. In all cases, the initial injury was far exceeded by the subsequent immune response and aggressive fibroinflammatory healing. Serial examination demonstrated progressive epithelial injury, mucosal inflammation, airway remodeling, and luminal compromise. Histologic findings in the first case demonstrate an early IL-17A response in the human airway following thermal injury. This is the first report implicating IL-17A in the airway mucosal immune response to thermal injury. Their second and third patients received Azithromycin targeting IL-17A and showed clinical responses. The third patient also presented with exposed tracheal cartilage and underwent mucosal reconstitution via split-thickness skin graft over an endoluminal stent in conjunction with tracheostomy. This was associated with rapid abatement of mucosal inflammation, resolution of granulation tissue, and return of laryngeal function. Patients who present with thermal inhalation injury should receive a thorough multidisciplinary airway evaluation, including early otolaryngologic evaluation. New early endoscopic approaches (scar lysis and mucosal reconstitution with autologous grafting over an endoluminal stent), when combined with targeted medical therapy aimed at components of mucosal airway inflammation (local corticosteroids and systemic Azithromycin targeting IL-17A), may have potential to limit chronic cicatricial complications.

TNFα and IL-17 alkalinize airway surface liquid through CFTR and pendrin

The pH of airway surface liquid (ASL) is a key factor that determines respiratory host defense; ASL acidification impairs and alkalinization enhances key defense mechanisms. Under healthy conditions, airway epithelia secrete base ([Formula: see text]) and acid (H⁺) to control ASL pH (pH_ASL). Neutrophil-predominant inflammation is a hallmark of several airway diseases, and TNFα and IL-17 are key drivers. However, how these cytokines perturb pH_ASL regulation is uncertain. In primary cultures of differentiated human airway epithelia, TNFα decreased and IL-17 did not change pH_ASL. However, the combination (TNFα+IL-17) markedly increased pH_ASL by increasing [Formula: see text] secretion. TNFα+IL-17 increased expression and function of two apical [Formula: see text] transporters, CFTR anion channels and pendrin Cl^-/[Formula: see text] exchangers. Both were required for maximal alkalinization. TNFα+IL-17 induced pendrin expression primarily in secretory cells where it was coexpressed with CFTR. Interestingly, significant pendrin expression was not detected in CFTR-rich ionocytes. These results indicate that TNFα+IL-17 stimulate [Formula: see text] secretion via CFTR and pendrin to alkalinize ASL, which may represent an important defense mechanism in inflamed airways.

Immunomodulation in Cystic Fibrosis: Why and How?

Cystic fibrosis (CF) lung disease is characterized by unconventional mechanisms of inflammation, implicating a chronic immune response dominated by innate immune cells. Historically, therapeutic development has focused on the mutated cystic fibrosis transmembrane conductance regulator (CFTR), leading to the discovery of small molecules aiming at modulating and potentiating the presence and activity of CFTR at the plasma membrane. However, treatment burden sustained by CF patients, side effects of current medications, and recent advances in other therapeutic areas have highlighted the need to develop novel disease targeting of the inflammatory component driving CF lung damage. Furthermore, current issues with standard treatment emphasize the need for directed lung therapies that could minimize systemic side effects. Here, we summarize current treatment used to target immune cells in the lungs, and highlight potential benefits and caveats of novel therapeutic strategies.

ILC2 Lung-Homing in Cystic Fibrosis Patients: Functional Involvement of CCR6 and Impact on Respiratory Failure

Cystic fibrosis patients suffer from a progressive, often fatal lung disease, which is based on a complex interplay between chronic infections, locally accumulating immune cells and pulmonary tissue remodeling. Although group-2 innate lymphoid cells (ILC2s) act as crucial initiators of lung inflammation, our understanding of their involvement in the pathogenesis of cystic fibrosis remains incomplete. Here we report a marked decrease of circulating CCR6⁺ ILC2s in the blood of cystic fibrosis patients, which significantly correlated with high disease severity and advanced pulmonary failure, strongly implicating increased ILC2 homing from the peripheral blood to the chronically inflamed lung tissue in cystic fibrosis patients. On a functional level, the CCR6 ligand CCL20 was identified as potent promoter of lung-directed ILC2 migration upon inflammatory conditions in vitro and in vivo using a new humanized mouse model with light-sheet fluorescence microscopic visualization of lung-accumulated human ILC2s. In the lung, blood-derived human ILC2s were able to augment local eosinophil and neutrophil accumulation and induced a marked upregulation of pulmonary type-VI collagen expression. Studies in primary human lung fibroblasts additionally revealed ILC2-derived IL-4 and IL-13 as important mediators of this type-VI collagen-inducing effect. Taken together, the here acquired results suggest that pathologically increased CCL20 levels in cystic fibrosis airways induce CCR6-mediated lung homing of circulating human ILC2s. Subsequent ILC2 activation then triggers local production of type-VI collagen and might thereby drive extracellular matrix remodeling potentially influencing pulmonary tissue destruction in cystic fibrosis patients. Thus, modulating the lung homing capacity of circulating ILC2s and their local effector functions opens new therapeutic avenues for cystic fibrosis treatment.