B75-34 LEI-515-mediated Monoacylglycerol Lipase Inhibition Attenuates Ventilator Induced Lung Injury in Mice

Rationale

Acute respiratory distress syndrome (ARDS) is a severe form of acute lung injury (ALI) that frequently requires mechanical ventilation. While lifesaving, mechanical ventilation can exacerbate lung injury, resulting in ventilator-induced lung injury (VILI), for which effective pharmacologic therapies remain limited. Endocannabinoids, particularly 2-arachidonoylglycerol (2-AG), are key regulators of inflammatory responses. The levels of 2-AG are tightly controlled by monoacylglycerol lipase (MAGL), a principal enzyme responsible for its degradation. Inhibition of MAGL has been shown to confer protection against inflammatory and mechanical tissue injury. Based on this rationale, we tested the hypothesis that pharmacological inhibition of MAGL attenuates VILI.

Methods

A two-hit murine lung injury model was employed using intratracheal administration of lipopolysaccharide (LPS) followed by high tidal volume (30ml/kg, 2h, 3 cm H2O positive end-expiratory pressure, with room air) mechanical ventilation. C57BL/6J mice received the peripherally restricted MAGL inhibitor LEI-515 (20 mg/kg, i.p.) after LPS exposure and before ventilation. At the end of ventilation, the total cell number and protein content in the bronchoalveolar lavage fluid (BALF) were determined. Neutrophil population and CD63 expression in neutrophils were assessed by flow cytometry. The levels of IL-1β, CXCL2, and arachidonic acid (AA) in the BALF were determined by ELISA. Lung injury was assessed by histology, and inflammatory signaling in the lung was assessed by immunoblot.

Results

MAGL inhibition with LEI-515 significantly reduced BALF total cell counts and protein content, which were elevated in response to VILI. Flow cytometry analysis showed that LEI-treated mice had a low neutrophil population and decreased neutrophil CD63 expression, indicating reduced neutrophil activation. In addition, BALF levels of IL-1β, CXCL2, and AA were markedly reduced in LEI-515-treated mice. Histological analysis revealed that MAGL inhibition reduced lung tissue injury. LEI-515 treatment significantly reduced VILI-induced NF-κB activation.

Conclusion

These findings demonstrate that MAGL inhibition attenuates ventilator-induced acute lung injury in mice, in part by reducing arachidonic acid-mediated inflammation and neutrophil activation, identifying MAGL as a promising therapeutic target for ARDS.

This abstract is funded by: NIEHS