Biology subjects

Britto, C. J.

Publications and source records attributed to Britto, C. J..

4 recordsLinked to original sources

bioRxiv2026

Lung hypoperfusion stimulates liquid absorption in alveoli

Tissue hypoperfusion is common in clinical settings, but how tissues respond to hypoperfusion on a microphysiological scale is not clear. We used real-time confocal microscopy of live, perfused lungs to gain insights into the effects of hypoperfusion on the microcirculation and microphysiology of lung alveoli, where gas exchange occurs. We focused on effects of hypoperfusion on alveolar liquid secretion, since alveolar liquid secretion is important for alveolar homeostatic functions. Our findings show lung hypoperfusion stimulated a reversal of alveolar liquid transport, from homeostatic liquid secretion to absorption. Specifically, lung perfusion at or near physiological perfusion pressure led to alveolar liquid secretion that depended on the alveolar epithelial cystic fibrosis transmembrane conductance regulator (CFTR), Na+-K+-Cl- cotransporters, and the Na+/K+-ATPase. Within minutes of halting lung perfusion or majorly reducing it, alveoli stopped secreting liquid and instead absorbed it via the epithelial Na+ channel, CFTR, and K+-Cl- cotransporters. We provide evidence that hypoperfusion caused alveolar microvessel lumens to shrink and airspaces to expand, leading to epithelial stretch that stimulated liquid absorption. These findings show lung hypoperfusion initiates mechanical signals that stimulate the alveolar epithelium to absorb liquid, and they may inform the pathogenesis of lung diseases characterized by acute microvascular hypoperfusion.

physiology↗

bioRxiv2026

Hijacking of inflammasome responses by the complement system during Pseudomonas aeruginosa-Aspergillus fumigatus sur-infection

Patients with cystic fibrosis (pwCF) are highly susceptible to chronic pulmonary infections due to mutations in the CFTR gene. From early childhood, pwCF experience repeated lung infections and often develop chronic bacterial and/or fungal colonization. Among the most clinically relevant pathogens, Pseudomonas aeruginosa and Aspergillus fumigatus frequently co-infect and are associated with worse outcomes, including excessive IL-1{beta}-driven inflammation and accelerated lung function decline. Here we investigated the mechanisms underlying inflammasome overactivation during super-infection. We found that inflammasome hyperactivation occurred across macrophage populations, was independent of exogenous priming, and required live co-infection with both pathogens. P. aeruginosa and A. fumigatus cooperatively activated the NLRP3 inflammasome, and this response required both caspase-1 and caspase-8. Unexpectedly, gasdermin D was dispensable for IL-1{beta} release. Bacterial flagellin, type IV pili and the type III secretion system, as well as the fungal polysaccharide galactosaminogalactan (GAG), were each required for overactivation. Mechanistically, P. aeruginosa activated the MyD88-TLR pathway, enhancing macrophage responses and promoting ITGAM (CD11b) expression. Under fungal super-infection, macrophages secreted complement component C3, which may bound fungal surface and engaged the complement receptor C3R (CD11b/CD18). Downstream SYK and ERK signaling amplified inflammasome activation and IL-1{beta} release. Single-cell transcriptomic analysis of pwCF broncho-alveolar lavage and lung samples supported coordinated upregulation of complement and inflammasome pathways during bacterial-fungal infection. Together, these findings identify a complement-inflammasome signaling axis that drives pathological inflammation during bacterial-fungal co-infection in airways of pwCF and may represent a therapeutic target.

immunology↗

bioRxiv2025

CFTR function in alveolar type 1 cells drives lung liquid secretion and host defense

Loss of the liquid layer that lines the lungs air-facing surface underpins mechanisms of major lung diseases, but the development of therapies that restore liquid secretion is hampered by an incomplete understanding of the cell types that drive it. Here, we show CFTR function in alveolar type 1 (AT1) cells - a cell type that comprises 95% of the lung surface but is presumed to be unimportant in CFTR-related diseases - is critical to lung liquid secretion and the secretion-mediated clearance of particles and S. aureus from lung alveoli. Our findings reveal essential roles for AT1 cells in lung homeostasis and defense, and they call for a reevaluation of the role of AT1 cells in CFTR-related diseases. We suggest AT1 cells be considered key targets of secretion-restoring therapies.

cell biology↗

bioRxiv2020

Decreased miR-24-3p potentiates DNA damage responses and increases susceptibility to COPD

Activation of the DNA damage response (DDR) due to chronic exposure to cigarette smoke (CS) is implicated in the pathogenesis of Chronic Obstructive Pulmonary Disease (COPD). However, not all smokers develop COPD and the pathologic consequences of CS exposure are heterogenous. Cellular mechanisms that regulate the DDR and contribute to disease progression in susceptible individuals are poorly understood. Because microRNAs are well known regulators of the DDR, we evaluated microRNA expression arrays performed on lung samples from 172 subjects with and without COPD. We identified miR-24-3p as the microRNA best correlated with radiographic emphysema ({rho}=-0.353, P=1.3e-04) and validated this finding in multiple cohorts. In a CS-exposure mouse model, miR-24-3p inhibition increased emphysema severity. In human airway epithelial cells, miR-24-3p suppressed apoptosis through the BH3-only protein BIM and suppressed homology-directed DNA repair and the DNA repair protein BRCA1. Finally, we found BIM and BRCA1 were increased in COPD lung tissue and inversely correlated with miR-24-3p expression. We concluded that decreased miR-24-3p expression increases COPD susceptibility and potentiates the DDR through BIM and BRCA1.

cell biology↗