Aberrant immune programming in neutrophils in cystic fibrosis

De novo DUOX2 expression in neutrophil subsets shapes the pathogenesis of intestinal disease

Infiltrating neutrophils are key effector cells in inflammatory bowel disease (IBD) while providing antimicrobial defense and tissue restitution in the intestine. The complexity of neutrophil functions in local environments underscores our limited understanding of how their adaptation in tissues influences disease progression. Here, we demonstrate that neutrophils recruited in murine colitis and infection models, idiopathic IBD, and chronic granulomatous disease-associated IBD undergo extensive transcriptional reprogramming, resulting in the emergence of neutrophil populations that feature unique DUOX2 NADPH oxidase expression. Functional studies utilizing mice with myeloid and neutrophil specific DUOX2 inactivation reveal a vital and dichotomous role for this NADPH oxidase in both colitis and intestinal infection. Niche-directed reprogramming promoted a DUOX2-dependent chemokine and cytokine-rich intestinal environment that amplified and prolonged inflammatory responses, suggesting that selectively suppressing DUOX2 may constitute an anti-inflammatory strategy for IBD treatment. Altering spatiotemporal redox signaling by de novo expression of a ROS-generating enzyme represents an important feature for functional neutrophil diversification in disease, with implications for other neutrophil-driven diseases in specialized niches.

Flow cytometric measurement of CFTR-mediated chloride transport in human neutrophils

Immune cells express a variety of ion channels and transporters in the plasma membrane and intracellular organelles, responsible of the transference of charged ions across hydrophobic lipid membrane barriers. The correct regulation of ion transport ensures proper immune cell function, activation, proliferation, and cell death. Cystic fibrosis (CF) is a genetic disease in which the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel gene is defective; consequently, the CFTR protein is dysfunctional, and the chloride efflux in CF cells is markedly impaired. CF is characterized by chronic inflammation in the airways, mainly triggered by neutrophilic infiltration and recurring bacterial infections, causing the decline of lung function and eventually respiratory failure. Novel modulator-based therapies have improved lung function in people with CF by increasing expression and function of CFTR in the plasma membrane of lung cells; however, the effects of these drugs in the lung-recruited inflammatory cells, specifically neutrophils, remains unknown. Given the complex biology of neutrophils and their short lifespan, we aimed to develop a fluorometric method to evaluate CFTR-mediated chloride transport in human neutrophils by using flow cytometry and the intracellular chloride-binding MQAE dye. Our results show that CFTR-mediated chloride transport in human neutrophils or human neutrophil-like cell lines can be consistently evaluated in vitro by this methodology. Additionally, this assay measured increased chloride efflux in neutrophils collected from people with CF under modulator therapy, as compared with healthy donors, indicating that this method can evaluate restoration of CFTR-mediated chloride transport in CF neutrophils.

Innate immune reprogramming in circulating neutrophils of COPD patients

BACKGROUND

Chronic obstructive pulmonary disease (COPD) involves both local and systemic neutrophilic inflammation, with dysregulation in blood neutrophil numbers, frequencies, and functions.

OBJECTIVE

We sought to characterize the transcriptional and epigenetic profiles of circulating neutrophils in patients with COPD and explore correlations with neutrophil dysfunction and clinical disease parameters.

METHODS

Circulating neutrophils of patients with COPD and control donors were subjected to RNA-sequencing and genome-wide analysis of histone 3 lysine 4 trimethylation (H3K4me3) by chromatin immunoprecipitation coupled with sequencing. Neutrophils' activation was assessed by cytofluorimetric analysis, O2- release, and Candida albicans phagocytosis assays.

RESULTS

RNA- and chromatin immunoprecipitation-sequencing analysis of H3K4me3 revealed a poised state in genes involved in innate immune activation, resembling the phenotype observed in neutrophils from individuals who are BCG-vaccinated, referred to as "trained," that is marked by weak or no expression under resting conditions but ready to be expressed at higher levels on stimulation. The epigenetic signature identified in neutrophils from subjects who are BCG-vaccinated was enriched in COPD neutrophils. In particular, and consistent with what has been described in "trained" neutrophils, COPD neutrophils exhibited transcriptional reprogramming of metabolically relevant genes. Functionally, COPD neutrophils produced higher CXCL8 and IL1B levels, released more O2-, and displayed greater phagocytic activity on in vitro stimulation.

CONCLUSIONS

These findings suggest that COPD neutrophils undergo epigenetic, transcriptomic, and metabolic reprogramming, which enhances their responsiveness and aligns with the phenotype of neutrophils previously identified as trained, offering mechanistic insight into the functional dysregulation observed in COPD.

Human mesenchymal stem cell therapy: Potential advances for reducing cystic fibrosis infection and organ inflammation

Innovation in cystic fibrosis (CF) supportive care, including implementing new antimicrobial agents, improved physiotherapy, and highly effective modulators therapy, has advanced patient survival into the 4th and 5th decades of life. However, even with these remarkable improvements in therapy, CF patients continue to suffer from pulmonary infection and other visceral organ complications associated with long-term deficient cystic fibrosis transmembrane conductance regulator (CFTR) expression. Human mesenchymal stem cells (MSCs) have been utilized in tissue engineering based upon their capacity to provide structural components of mesenchymal tissues. An alternative role of MSCs, however is their versatile utilization as cell-based infusion powerhouses due to the unique capacity to deliver milieu specific soluble biologic factors, promoting immune supportive antimicrobial and anti-inflammatory potency. MSCs derived from umbilical cord blood, bone marrow, adipose and other tissues can be expanded in ex vivo using good manufacturing procedure facilities for a safe, unique therapeutic to reduce and limit CF infection and facilitate the resolution of multi-organ inflammation. In our efforts, we conducted extensive preclinical development and validation of an allogeneic derived bone marrow derived MSC product in preparation for a clinical trial in CF. In this process, potency models were developed to ensure the functional capacity of the MSC product to provide clinical benefit. In vitro, murine in vivo and patient tissue ex vivo potency models were utilized to follow MSC anti-infective and anti-inflammatory potency associated with the CFTR deficient environment. We showed in our "First in CF" clinical trial that the allogeneic MSCs obtained from healthy volunteer bone marrow samples were safe. The advent of improved CF care measures and exciting new small molecules has changed the survival and morbidity phenotype of patients with CF, however, there are CF patients who cannot tolerate or have genotypes that are non-responsive to modulators. Additionally, even with the small molecule therapy, CF patients are living longer, but without genetic correction, with the CF disease manifestation aggravated by the continuance of pre-existing CFTR-associated clinical issues such as ongoing inflammation. MSCs secrete bio-active factors that enhance and protect tissue function and can promote "self-immune" regulation. These properties can provide therapeutic support for the traditional and changing face of CF disease clinical complications. Further, MSC-derived bio-active factors can directly mitigate colonizing pathogens' survival by producing antimicrobial peptides (AMPs) which change the pathogen surface and increase host recognition, elimination, and sensitivity to antibiotics. Herein, we review the potential of MSC therapeutics for treating many facets of CF, emphasizing the potential for providing great additive therapeutics for managing morbidity and quality of life.

Inhibiting CFTR through inh-172 in primary neutrophils reveals CFTR-specific functional defects

The lungs of people with cystic fibrosis (PwCF) are characterized by recurrent bacterial infections and inflammation. Infections in cystic fibrosis (CF) are left unresolved despite excessive neutrophil infiltration. The role of CFTR in neutrophils is not fully understood. In this study, we aimed to assess which antimicrobial functions are directly impaired by loss of CFTR function in neutrophils. In order to do so, we used a specific inhibitor of CFTR ion channel activity, inh-172. CF neutrophils from PwCF harboring severe CFTR mutations were additionally isolated to further discern CFTR-specific functional defects. We evaluated phagocytosis, reactive oxygen species (ROS) production, neutrophil elastase (NE) and myeloperoxidase (MPO) exocytosis and bacterial killing. The inh-172 model identified decreased acidification of the phagosome, increased bacterial survival and decreased ROS production upon stimulation. In PwCF neutrophils, we observed reduced degranulation of both NE and MPO. When co-culturing neutrophils with CF sputum supernatant and airway epithelial cells, the extent of phagocytosis was reduced, underscoring the importance of recreating an inflammatory environment as seen in PwCF lungs to model immune responses in vitro. Despite low CFTR expression in blood neutrophils, functional defects were found in inh-172-treated and CF neutrophils. The inh-172 model disregards donor variability and allows pinpointing neutrophil functions directly impaired by dysfunctional CFTR.

Anti-inflammatory effects of elexacaftor/tezacaftor/ivacaftor in adults with cystic fibrosis heterozygous for F508del

Inflammation is a key driver in the pathogenesis of cystic fibrosis (CF). We assessed the effectiveness of elexacaftor/tezacaftor/ivacaftor (ETI) therapy on downregulating systemic and immune cell-derived inflammatory cytokines. We also monitored the impact of ETI therapy on clinical outcome. Adults with CF, heterozygous for F508del (n = 19), were assessed at baseline, one month and three months following ETI therapy, and clinical outcomes were measured, including sweat chloride, lung function, weight, neutrophil count and C-reactive protein (CRP). Cytokine quantifications were measured in serum and following stimulation of peripheral blood mononuclear cells (PBMCs) with lipopolysaccharide (LPS) and adenosine triphosphate and analysed using LEGEND plex™ Human Inflammation Panel 1 by flow cytometry (n = 19). ASC specks were measured in serum and caspase-1 activity and mRNA levels determined from stimulated PBMCs were determined. Patients remained stable over the study period. ETI therapy resulted in decreased sweat chloride concentrations (p < 0.0001), CRP (p = 0.0112) and neutrophil count (p = 0.0216) and increased percent predicted forced expiratory volume (ppFEV1) (p = 0.0399) from baseline to three months, alongside a trend increase in weight. Three months of ETI significantly decreased IL-18 (p< 0.0011, p < 0.0001), IL-1β (p<0.0013, p = 0.0476), IL-6 (p = 0.0109, p = 0.0216) and TNF (p = 0.0028, p = 0.0033) levels in CF serum and following PBMCs stimulation respectively. The corresponding mRNA levels were also found to be reduced in stimulated PBMCs, as well as reduced ASC specks and caspase-1 levels, indicative of NLRP3-mediated production of pro-inflammatory cytokines, IL-1β and IL-18. While ETI therapy is highly effective at reducing sweat chloride and improving lung function, it also displays potent anti-inflammatory properties, which are likely to contribute to improved long-term clinical outcomes.

Cystic fibrosis in the era of CFTR modulators: did the neutrophil slip through the cracks?

Neutrophil abnormalities are present in patients with cystic fibrosis treated with CFTR modulators.

Modulator-refractory cystic fibrosis: Defining the scope and challenges of an emerging at-risk population

Cystic fibrosis (CF) causes life-shortening respiratory and systemic disease due to dysfunction of the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel. Highly effective modulator therapies (HEMT) improve the lives of many people with cystic fibrosis (PwCF) by correcting the structure and function of the defective CFTR channel at the molecular level. Despite these advancements, a subset of patients-termed modulator-refractory CF-continues to experience two or more pulmonary exacerbations per year requiring hospitalization or intravenous antibiotics, regardless of other modulator benefits. This underrecognized group represents an emerging challenge within the CF community. We discuss the benefits and limitations of current CFTR modulator therapies and the urgent need to investigate this emerging at-risk population. While HEMT improves lung function, decreases exacerbations, reduces the need for lung transplantation, and lowers mortality, increasing evidence shows that not all patients benefit equally. At the University of Virginia, nearly 6% of adults with CF exhibit the modulator-refractory phenotype. The driving factors of modulator-refractory CF are likely multifactorial, including genetic variations, variable immune responses, preexisting bronchiectasis, microbiological colonization, preexisting comorbid conditions, and environmental and socioeconomic factors. This perspective review recognizes and defines modulator-refractory CF as a distinct emerging clinical phenotype in the post-modulator era. Understanding this phenotype is crucial for reducing morbidity and mortality, and for improving the quality of life for PwCF. Raising awareness of modulator-refractory CF will help the community address this population and perform further research to identify causes. The emergence of modulator-refractory CF highlights a significant gap in our current treatment landscape and provides an opportunity to develop innovative therapeutic strategies that may benefit the entire CF community, ensuring that no person with CF is left behind.