Daily Ards Research Analysis
Aging heightens endothelial barrier dysfunction during mechanical ventilation, revealed by in vivo and single-cell transcriptomic analyses, underscoring tailored strategies for elderly ARDS patients. A patient-specific physiomechanical ARDS simulation framework (MEGA) qualitatively predicts responses to prone positioning and PEEP, pending calibration for clinical use. Macrophage TREM2/DAP12 signaling limits ferroptosis and mitigates murine lung injury, nominating an immunometabolic target for AR
Summary
Aging heightens endothelial barrier dysfunction during mechanical ventilation, revealed by in vivo and single-cell transcriptomic analyses, underscoring tailored strategies for elderly ARDS patients. A patient-specific physiomechanical ARDS simulation framework (MEGA) qualitatively predicts responses to prone positioning and PEEP, pending calibration for clinical use. Macrophage TREM2/DAP12 signaling limits ferroptosis and mitigates murine lung injury, nominating an immunometabolic target for ARDS.
Research Themes
- Aging and ventilator-induced lung injury mechanisms
- Computational personalization of ARDS ventilatory management
- Macrophage ferroptosis and immunometabolic targets in lung injury
Selected Articles
1. Effect of aging on pulmonary cellular responses during mechanical ventilation.
In ventilated mice, aging amplified surfactant dysfunction and microvascular leak but attenuated inflammatory signaling. Single-cell RNA-Seq revealed blunted macrophage responses and altered endothelial junction programs, with in vitro assays confirming impaired endothelial barrier in aged cells.
Impact: This integrates in vivo physiology with single-cell transcriptomics to pinpoint aging-related endothelial vulnerability during mechanical ventilation, informing ARDS risk in elderly patients.
Clinical Implications: Elderly patients may require stricter lung-protective ventilation (lower driving pressure and tidal strain) and fluid-conservative strategies; endothelial-protective interventions merit testing.
Key Findings
- Aging increased surfactant dysfunction and microvascular permeability during mechanical ventilation.
- Inflammatory responses were attenuated in aged lungs, with blunted alveolar macrophage activation.
- Aged endothelial cells showed altered cell-cell junction programs and impaired barrier formation in vitro.
Methodological Strengths
- Combined in vivo ventilator injury model with single-cell RNA-Seq for cell-resolved insights
- Functional validation of endothelial barrier defects using in vitro assays
Limitations
- Preclinical murine study with male mice limits generalizability to human, female, and diverse clinical populations
- Short-term injury assessment without long-term outcome evaluation
Future Directions: Test endothelial-targeted and surfactant-stabilizing strategies in aged models; validate single-cell signatures and barrier phenotypes in human ARDS cohorts.
Acute respiratory distress syndrome (ARDS) results in substantial morbidity and mortality, especially in elderly people. Mechanical ventilation, a common supportive treatment for ARDS, is necessary for maintaining gas exchange but can also propagate injury. We hypothesized that aging leads to alterations in surfactant function, inflammatory signaling, and microvascular permeability within the lung during mechanical ventilation. Young and aged male mice were mechanically ventilated, and surfactant function, inflammation, and vascular permeability were assessed. Additionally, single-cell RNA-Seq was used to delineate cell-specific transcriptional changes. The results showed that, in aged mice, surfactant dysfunction and vascular permeability were significantly augmented, while inflammation was less pronounced. Differential gene expression and pathway analyses revealed that alveolar macrophages in aged mice showed a blunted inflammatory response, while aged endothelial cells exhibited altered cell-cell junction formation. In vitro functional analysis revealed that aged endothelial cells had an impaired ability to form a barrier. These results highlight the complex interplay between aging and mechanical ventilation, including an age-related predisposition to endothelial barrier dysfunction, due to altered cell-cell junction formation, and decreased inflammation, potentially due to immune exhaustion. It is concluded that age-related vascular changes may underlie the increased susceptibility to injury during mechanical ventilation in elderly patients.
2. MEGA: a computational framework to simulate the acute respiratory distress syndrome.
MEGA couples physiology and lung mechanics using patient CT data to simulate ARDS responses to prone positioning and PEEP changes. Outputs qualitatively matched literature and bedside measures but required calibration for quantitative accuracy.
Impact: Introduces a patient-specific computational framework that could personalize ventilatory strategies in ARDS and accelerate hypothesis testing in silico.
Clinical Implications: If calibrated and prospectively validated, such simulations could inform PEEP titration and proning decisions for individual patients, potentially reducing ventilator-induced lung injury.
Key Findings
- Developed a CT-based coupled physiomechanical ARDS simulation framework (MEGA).
- Simulated responses to prone positioning and PEEP increments with qualitative agreement to clinical/literature data.
- Observed quantitative discrepancies highlighting the need for model calibration before clinical deployment.
Methodological Strengths
- Patient-specific modeling leveraging imaging-derived lung structure
- Comparative evaluation against clinical measurements and literature
Limitations
- Quantitative mismatches indicate under-calibration and lack of external validation
- Proof-of-concept without prospective clinical integration or outcome testing
Future Directions: Perform rigorous calibration with multicenter datasets, incorporate patient-specific recruitability and perfusion, and prospectively test decision-support integration.
The acute respiratory distress syndrome (ARDS) is a critical condition that necessitates mechanical ventilation (MV) to ensure sufficient ventilation and oxygenation for patients. Intensivists employ various therapeutic tools such as adjusting positive end-expiratory pressure (PEEP) levels or positioning the patient prone. However, practitioners encounter several challenges when dealing with ARDS: high variability among patients and limited understanding of underlying mechanisms. As a result, decision-making by physicians largely relies on experience. Yet, having the ability to estimate the likelihood of a patient responding to different therapeutic approaches would hold significant clinical value. Moreover, gaining a deeper understanding of the biomechanical and physiological phenomena underlying patient responses could inform the development of new MV strategies for ARDS management. To address these challenges, a coupled physiomechanical computational framework based on patient's computed tomography scan data was conceived and implemented. Simulations were conducted for prone positioning and PEEP-increment scenarios. The model results qualitatively align with both literature data and clinical measurements. However, some results diverge quantitatively from clinical measurements, emphasizing the necessity for thorough model calibration. Nonetheless, this serves as a proof of concept that the developed framework could be valuable in supporting intensivists' decision-making processes.
3. TREM2 protects against LPS-induced murine acute lung injury through suppressing macrophage ferroptosis.
TREM2 expression falls in LPS-induced ALI, and augmenting TREM2 in macrophages dampens cytokines, oxidative stress, and iron-related injury while adoptive transfer reduces lung inflammation. Data implicate the TREM2/DAP12 axis in restraining macrophage ferroptosis, positioning TREM2 as a therapeutic target.
Impact: Reveals an immunometabolic mechanism—macrophage ferroptosis—controlled by TREM2/DAP12 that modulates lung injury severity, offering a druggable axis for ARDS.
Clinical Implications: While preclinical, targeting TREM2 signaling or ferroptosis pathways may complement lung-protective ventilation in ARDS; macrophage-based therapies warrant exploration.
Key Findings
- TREM2 is downregulated in LPS-treated macrophages and murine ALI via p38 MAPK and STAT6 activation.
- TREM2 overexpression reduces DAP12, pro-inflammatory cytokines, MDA, and hemosiderin accumulation; knockdown increases IL-6, ROS, LDH, and hemosiderin.
- Adoptive transfer of TREM2-overexpressing macrophages suppresses lung inflammation in murine ALI, implicating TREM2/DAP12 in restraining macrophage ferroptosis.
Methodological Strengths
- Combined in vitro macrophage manipulation with in vivo adoptive transfer in ALI model
- Measured multiple ferroptosis and injury markers (cytokines, ROS, MDA, LDH, hemosiderin)
Limitations
- Murine LPS-induced ALI model may not fully recapitulate human ARDS pathophysiology
- Sample sizes and long-term outcomes were not detailed; no human validation
Future Directions: Dissect upstream regulators of TREM2 in ARDS, test pharmacologic TREM2 agonism or ferroptosis inhibitors, and validate in human macrophages and clinical biospecimens.
Triggering receptor expressed on myeloid cells-2 (TREM2) is a cell surface receptor, majorly expressed by granulocytes, monocytes and macrophages. We in this study showed that TREM2 was downregulated in the lipopolysaccharide (LPS)-treated macrophages and murine acute lung injury (ALI) through activation of p38 MAPK and STAT6 signaling. Over-expression of TREM2 reduced the expression of DNAX-activation protein 12 (DAP12), pro-inflammatory cytokines (TNF-α, IL-6, IL-1β), Malondialdehyde (MDA) and hemosiderin accumulation in LPS-treated macrophages. Knockdown of TREM2 expression elevated the expression of IL-6, reactive oxygen species (ROS), lactate dehydrogenases (LDH) and hemosiderin accumulation. Intratracheal adoptive transfer of TREM2-overexpressing macrophages effectively suppressed the lung inflammation and pro-inflammatory cytokine expression in murine ALI. While downregulation of TREM2 enhanced the lung inflammation in the lung tissues of murine ALI. Therefore, TREM2/DAP12 axis is involved in macrophage ferroptosis and attenuation of murine ALI. TREM2 would be a novel therapeutic target in murine ALI and patients with acute respiratory distress syndrome (ARDS).