α7nAChR activation in AT2 cells promotes alveolar regeneration through WNT7B signaling in acute lung injury

Nebulized M2 macrophage-derived nanovesicles for the treatment of explosion-induced acute lung injury

Gas explosion-induced acute lung injury (ALI) presents a significant clinical challenge in industrial and military contexts, yet current therapeutic interventions remain suboptimal. Extracellular vesicles (EVs) have emerged as promising nanoscale therapeutic agents, owing to their superior biocompatibility and inherent therapeutic potential. In this study, we engineered and isolated alternatively activated macrophages extracellular vesicles (M2-EVs) and administered them via nebulization to the injured lung tissue in an established murine model of blast-induced ALI. Administration of M2-EVs led to a significant amelioration of pulmonary function, characterized by decreased lung injury scores and attenuated inflammatory markers. Mechanistically, M2-EVs promoted the M1-to-M2 phenotypic transition of pulmonary macrophages, modulated the P62-Keap1-Nrf2 signaling pathway, and consequently mitigated excessive autophagy and oxidative stress. Collectively, these findings not only offer mechanistic insights into the pathogenesis of blast-induced ALI but also highlight M2-EVs as a promising cell-free therapeutic approach for explosion-related pulmonary injuries.

Targeting α7 Nicotinic Acetylcholine Receptor for Modulating the Neuroinflammation of Dry Eye Disease Via Macrophages

Purpose

Patients with dry eye disease (DED) often exhibit neurological abnormalities and may even suffer from neuropathic pain and pain-related anxiety or depression. The α-7 nicotinic acetylcholine receptor (α7nAChR) is a pivotal regulator in the anti-inflammatory pathway connecting the nervous and immune systems, Here, we investigate the potential of α7nAChR agonist as a novel treatment for DED.

Methods

We induced DED model by unilateral excision of extraorbital lachrymal gland in C57/BL6 mice. After seven days of treatment, RNA sequencing was performed to identify differentially expressed genes in the cornea of lacrimal gland excision (LGE) mice. Quantitative polymerase chain reaction, Western blotting, and flow cytometry tests were carried out to elucidate neuroinflammation changes after α7nAChR activation. Corneal nerve abnormalities were assessed by corneal esthesiometry and immunofluorescence staining.

Results

The activation of α7nAChR stimulates genes involved in immune-mediated inflammatory progression and neuroregulation, inhibits the expression of transient receptor potential vanilloid-1, reinstates corneal nerve density, and alleviates anxiety-like behaviors associated with severe DED. Furthermore, we demonstrated that α7nAChR agonist restored corneal nerve abnormality and alleviated inflammation response by down-regulating the proportion of CD86+ M1 macrophages (proinflammatory phenotypes).

Conclusions

Our findings underscore the activation of α7nAChR as a pioneering therapeutic approach for preserving corneal nerves balance and controlling inflammation in DED.

Characterization of dipyridamole as a novel ferroptosis inhibitor and its therapeutic potential in acute respiratory distress syndrome management

Rationale: Ferroptosis in lung epithelium and endothelium contributes to the pathogenesis of acute respiratory distress syndrome (ARDS), a critical and often fatal condition marked by acute inflammation and elevated pulmonary vascular permeability. Despite this, there are currently no FDA-approved therapeutics specifically targeting ferroptosis for ARDS management. Methods: A screening of 259 FDA-approved drugs was conducted to identify an effective ferroptosis inhibitor in pulmonary epithelial and endothelial cells. The anti-ferroptotic and therapeutic efficacy of this screened drug was rigorously evaluated using two distinct ARDS mouse models (LPS-induced acute lung injury and CLP-induced sepsis) and human airway organoids (hAOs). The regulatory mechanism of this drug on ferroptosis inhibition was investigated via RNA-sequencing, qRT-PCR, western blotting, IF, luciferase reporter assay, chromatin immunoprecipitation assay, limited proteolysis-mass spectrometry assay, cellular thermal shift assay, and drug affinity responsive target stability assay. Furthermore, a proof-of-concept clinical trial was conducted, wherein ARDS patients were administered with the drug as adjunctive therapy. Results: Dipyridamole (DIPY) was identified as a potent inhibitor of ferroptosis in pulmonary epithelial and endothelial cells. DIPY effectively mitigated ferroptosis and pulmonary damage in both mouse models and hAOs, primarily by downregulating heme oxygenase 1 (HMOX1). The transcription factor cAMP responsive element binding protein 1 (CREB1) was identified as a key transactivator of HMOX1, which DIPY effectively downregulated. Mechanistically, DIPY binds to and activates superoxide dismutase 1 (SOD1), which in turn inhibits the CREB1/HMOX1 pathway, thereby suppressing ferroptosis. Notably, the clinical trial further corroborated the therapeutic potential of DIPY in ARDS patients, demonstrating improved outcomes with DIPY adjunctive therapy. Conclusions: These findings provide compelling evidence that DIPY inhibits ferroptosis in pulmonary epithelial and endothelial cells by modulating the SOD1/CREB1/HMOX1 signaling axis and suggest DIPY as a promising therapeutic strategy for ARDS treatment.

Activation of nicotinic acetylcholine receptor α7 subunit limits Zika viral infection via promoting autophagy and ferroptosis

Vagus nerve regulates viral infection and inflammation via the alpha 7 nicotinic acetylcholine receptor (α7 nAChR); however, the role of α7 nAChR in ZIKA virus (ZIKV) infection, which can cause severe neurological diseases such as microcephaly and Guillain-Barré syndrome, remains unknown. Here, we first examined the role of α7 nAChR in ZIKV infection in vitro. A broad effect of α7 nAChR activation was identified in limiting ZIKV infection in multiple cell lines. Combined with transcriptomics analysis, we further demonstrated that α7 nAChR activation promoted autophagy and ferroptosis pathways to limit cellular ZIKV viral loads. Additionally, activation of α7 nAChR prevented ZIKV-induced p62 nucleus accumulation, which mediated an enhanced autophagy pathway. By regulating proteasome complex and an E3 ligase NEDD4, activation of α7 nAChR resulted in increased amount of cellular p62, which further enhanced the ferroptosis pathway to reduce ZIKV infection. Moreover, utilizing in vivo neonatal mouse models, we showed that α7 nAChR is essential in controlling the disease severity of ZIKV infection. Taken together, our findings identify an α7 nAChR-mediated effect that critically contributes to limiting ZIKV infection, and α7 nAChR activation offers a novel strategy for combating ZIKV infection and its complications.

Vagal-α7 nicotinic acetylcholine receptor signaling exacerbates influenza severity by promoting lung epithelial cell infection

The vagus nerve circuit, operating through the alpha-7 nicotinic acetylcholine receptor (α7 nAChR), regulates the inflammatory response by influencing immune cells. However, the role of vagal-α7 nAChR signaling in influenza virus infection is unclear. In particular, does vagal-α7 nAChR signaling impact the infection of alveolar epithelial cells (AECs), the primary target cells of influenza virus? Here, we demonstrated a distinct role of α7 nAChR in type II AECs compared to its role in immune cells during influenza infection. We found that deletion of Chrna7 (encoding gene of α7 nAChR) in type II AECs or disruption of vagal circuits reduced lung influenza infection and protected mice from influenza-induced lung injury. We further unveiled that activation of α7 nAChR enhanced influenza infection through PTP1B-NEDD4L-ASK1-p38MAPK pathway. Mechanistically, activation of α7 nAChR signaling decreased p38MAPK phosphorylation during infection, facilitating the nuclear export of influenza viral ribonucleoproteins and thereby promoting infection. Taken together, our findings reveal a mechanism mediated by vagal-α7 nAChR signaling that promotes influenza viral infection and exacerbates disease severity. Targeting vagal-α7 nAChR signaling may offer novel strategies for combating influenza virus infections.

Repair and regeneration of the alveolar epithelium in lung injury

Considerable progress has been made in understanding the function of alveolar epithelial cells in a quiescent state and regeneration mechanism after lung injury. Lung injury occurs commonly from severe viral and bacterial infections, inhalation lung injury, and indirect injury sepsis. A series of pathological mechanisms caused by excessive injury, such as apoptosis, autophagy, senescence, and ferroptosis, have been studied. Recovery from lung injury requires the integrity of the alveolar epithelial cell barrier and the realization of gas exchange function. Regeneration mechanisms include the participation of epithelial progenitor cells and various niche cells involving several signaling pathways and proteins. While alveoli are damaged, alveolar type II (AT2) cells proliferate and differentiate into alveolar type I (AT1) cells to repair the damaged alveolar epithelial layer. Alveolar epithelial cells are surrounded by various cells, such as fibroblasts, endothelial cells, and various immune cells, which affect the proliferation and differentiation of AT2 cells through paracrine during alveolar regeneration. Besides, airway epithelial cells also contribute to the repair and regeneration process of alveolar epithelium. In this review, we mainly discuss the participation of epithelial progenitor cells and various niche cells involving several signaling pathways and transcription factors.

Neuroimmune recognition and regulation in the respiratory system

Neuroimmune recognition and regulation in the respiratory system is a complex and highly coordinated process involving interactions between the nervous and immune systems to detect and respond to pathogens, pollutants and other potential hazards in the respiratory tract. This interaction helps maintain the health and integrity of the respiratory system. Therefore, understanding the complex interactions between the respiratory nervous system and immune system is critical to maintaining lung health and developing treatments for respiratory diseases. In this review, we summarise the projection distribution of different types of neurons (trigeminal nerve, glossopharyngeal nerve, vagus nerve, spinal dorsal root nerve, sympathetic nerve) in the respiratory tract. We also introduce several types of cells in the respiratory epithelium that closely interact with nerves (pulmonary neuroendocrine cells, brush cells, solitary chemosensory cells and tastebuds). These cells are primarily located at key positions in the respiratory tract, where nerves project to them, forming neuroepithelial recognition units, thus enhancing the ability of neural recognition. Furthermore, we summarise the roles played by these different neurons in sensing or responding to specific pathogens (influenza, severe acute respiratory syndrome coronavirus 2, respiratory syncytial virus, human metapneumovirus, herpes viruses, Sendai parainfluenza virus, Mycobacterium tuberculosis, Pseudomonas aeruginosa, Staphylococcus aureus, amoebae), allergens, atmospheric pollutants (smoking, exhaust pollution), and their potential roles in regulating interactions among different pathogens. We also summarise the prospects of bioelectronic medicine as a third therapeutic approach following drugs and surgery, as well as the potential mechanisms of meditation breathing as an adjunct therapy.