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Haynes ME, Sullivan DP, Muller WA. Neutrophil Infiltration and Function in the Pathogenesis of Inflammatory Airspace Disease. THE AMERICAN JOURNAL OF PATHOLOGY 2024; 194:628-636. [PMID: 38309429 PMCID: PMC11074974 DOI: 10.1016/j.ajpath.2023.12.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 12/07/2023] [Accepted: 12/21/2023] [Indexed: 02/05/2024]
Abstract
Neutrophils are an important cell type often considered the body's first responders to inflammatory insult or damage. They are recruited to the tissue of the lungs in patients with inflammatory airspace diseases and have unique and complex functions that range from helpful to harmful. The uniqueness of these functions is due to the heterogeneity of the inflammatory cascade and retention in the vasculature. Neutrophils are known to marginate, or remain stagnant, in the lungs even in nondisease conditions. This review discusses the ways in which the recruitment, presence, and function of neutrophils in the airspace of the lungs are unique from those of other tissues, and the complex effects of neutrophils on pathogenesis. Inflammatory mediators produced by neutrophils, such as neutrophil elastase, proresolving mediators, and neutrophil extracellular traps, dramatically affect the outcomes of patients with disease of the lungs.
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Affiliation(s)
- Maureen E Haynes
- Department of Pathology, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - David P Sullivan
- Department of Pathology, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - William A Muller
- Department of Pathology, Northwestern University Feinberg School of Medicine, Chicago, Illinois.
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Experimental Models of Acute Lung Injury: their Advantages and Limitations. ACTA MEDICA MARTINIANA 2020. [DOI: 10.2478/acm-2020-0011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Abstract
Acute damage to the lung may originate from various direct and indirect reasons. Direct lung injury may be caused by pneumonia, near-drowning, aspiration, inhalation of toxic gases etc., while indirect lung injury is secondary, following any severe extra-pulmonary disease, e.g. sepsis, acute pancreatitis, or severe trauma. Due to a complex pathophysiology of the acute lung injury, the treatment is also extremely complicated and except for lung-protective ventilation there have been no specific treatment approaches recommended. An urgent need for a reliable and sufficiently effective treatment forces the researchers into testing novel therapeutic strategies. However, most of these determinations should be done in the laboratory conditions using animals. Complex methods of preparation of various experimental models of the acute lung injury has gradually developed within decades. Nowadays, there have been the models of direct, indirect, or mixed lung injury well established, as well as the models evoked by a combination of two triggering factors. Although the applicability of the results from animal experiments to patients might be limited by many factors, animal models are essential for understanding the patho-physiology of acute lung injury and provide an exceptional opportunity to search for novel therapeutical strategies.
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Alejandre Alcazar MA, Kaschwich M, Ertsey R, Preuss S, Milla C, Mujahid S, Masumi J, Khan S, Mokres LM, Tian L, Mohr J, Hirani DV, Rabinovitch M, Bland RD. Elafin Treatment Rescues EGFR-Klf4 Signaling and Lung Cell Survival in Ventilated Newborn Mice. Am J Respir Cell Mol Biol 2019; 59:623-634. [PMID: 29894205 DOI: 10.1165/rcmb.2017-0332oc] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Mechanical ventilation with O2-rich gas (MV-O2) inhibits alveologenesis and lung growth. We previously showed that MV-O2 increased elastase activity and apoptosis in lungs of newborn mice, whereas elastase inhibition by elafin suppressed apoptosis and enabled lung growth. Pilot studies suggested that MV-O2 reduces lung expression of prosurvival factors phosphorylated epidermal growth factor receptor (pEGFR) and Krüppel-like factor 4 (Klf4). Here, we sought to determine whether apoptosis and lung growth arrest evoked by MV-O2 reflect disrupted pEGFR-Klf4 signaling, which elafin treatment preserves, and to assess potential biomarkers of bronchopulmonary dysplasia (BPD). Five-day-old mice underwent MV with air or 40% O2 for 8-24 hours with or without elafin treatment. Unventilated pups served as controls. Immunoblots were used to assess lung pEGFR and Klf4 proteins. Cultured MLE-12 cells were exposed to AG1478 (EGFR inhibitor), Klf4 siRNA, or vehicle to assess effects on proliferation, apoptosis, and EGFR regulation of Klf4. Plasma elastase and elafin levels were measured in extremely premature infants. In newborn mice, MV with air or 40% O2 inhibited EGFR phosphorylation and suppressed Klf4 protein content in lungs (vs. unventilated controls), yielding increased apoptosis. Elafin treatment inhibited elastase, preserved lung pEGFR and Klf4, and attenuated the apoptosis observed in lungs of vehicle-treated mice. In MLE-12 studies, pharmacological inhibition of EGFR and siRNA suppression of Klf4 increased apoptosis and reduced proliferation, and EGFR inhibition decreased Klf4. Plasma elastase levels were more than twofold higher, without a compensating increase of plasma elafin, in infants with BPD, compared to infants without BPD. These findings indicate that pEGFR-Klf4 is a novel prosurvival signaling pathway in lung epithelium that MV disrupts. Elafin preserves pEGFR-Klf4 signaling and inhibits apoptosis, thereby enabling lung growth during MV. Together, our animal and human data raise the question: would elastase inhibition prevent BPD in high-risk infants exposed to MV-O2?
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Affiliation(s)
- Miguel A Alejandre Alcazar
- 1 Department of Pediatrics, Stanford University School of Medicine, Stanford, California; and.,2 Department of Pediatric and Adolescent Medicine, Center of Molecular Medicine Cologne, University Hospital of Cologne, Cologne, Germany
| | - Mark Kaschwich
- 1 Department of Pediatrics, Stanford University School of Medicine, Stanford, California; and
| | - Robert Ertsey
- 1 Department of Pediatrics, Stanford University School of Medicine, Stanford, California; and
| | - Stefanie Preuss
- 1 Department of Pediatrics, Stanford University School of Medicine, Stanford, California; and
| | - Carlos Milla
- 1 Department of Pediatrics, Stanford University School of Medicine, Stanford, California; and
| | - Sana Mujahid
- 1 Department of Pediatrics, Stanford University School of Medicine, Stanford, California; and
| | - Juliet Masumi
- 1 Department of Pediatrics, Stanford University School of Medicine, Stanford, California; and
| | - Suleman Khan
- 1 Department of Pediatrics, Stanford University School of Medicine, Stanford, California; and
| | - Lucia M Mokres
- 1 Department of Pediatrics, Stanford University School of Medicine, Stanford, California; and
| | - Lu Tian
- 1 Department of Pediatrics, Stanford University School of Medicine, Stanford, California; and
| | - Jasmine Mohr
- 2 Department of Pediatric and Adolescent Medicine, Center of Molecular Medicine Cologne, University Hospital of Cologne, Cologne, Germany
| | - Dharmesh V Hirani
- 2 Department of Pediatric and Adolescent Medicine, Center of Molecular Medicine Cologne, University Hospital of Cologne, Cologne, Germany
| | - Marlene Rabinovitch
- 1 Department of Pediatrics, Stanford University School of Medicine, Stanford, California; and
| | - Richard D Bland
- 1 Department of Pediatrics, Stanford University School of Medicine, Stanford, California; and
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Cytosolic Phospholipase A 2α Promotes Pulmonary Inflammation and Systemic Disease during Streptococcus pneumoniae Infection. Infect Immun 2017; 85:IAI.00280-17. [PMID: 28808157 DOI: 10.1128/iai.00280-17] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Accepted: 08/02/2017] [Indexed: 02/07/2023] Open
Abstract
Pulmonary infection by Streptococcus pneumoniae is characterized by a robust alveolar infiltration of neutrophils (polymorphonuclear cells [PMNs]) that can promote systemic spread of the infection if not resolved. We previously showed that 12-lipoxygenase (12-LOX), which is required to generate the PMN chemoattractant hepoxilin A3 (HXA3) from arachidonic acid (AA), promotes acute pulmonary inflammation and systemic infection after lung challenge with S. pneumoniae As phospholipase A2 (PLA2) promotes the release of AA, we investigated the role of PLA2 in local and systemic disease during S. pneumoniae infection. The group IVA cytosolic isoform of PLA2 (cPLA2α) was activated upon S. pneumoniae infection of cultured lung epithelial cells and was critical for AA release from membrane phospholipids. Pharmacological inhibition of this enzyme blocked S. pneumoniae-induced PMN transepithelial migration in vitro Genetic ablation of the cPLA2 isoform cPLA2α dramatically reduced lung inflammation in mice upon high-dose pulmonary challenge with S. pneumoniae The cPLA2α-deficient mice also suffered no bacteremia and survived a pulmonary challenge that was lethal to wild-type mice. Our data suggest that cPLA2α plays a crucial role in eliciting pulmonary inflammation during pneumococcal infection and is required for lethal systemic infection following S. pneumoniae lung challenge.
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