Could the RAGE-dependent effects of inhaled sevoflurane on lung epithelial permeability help identifying a treatable trait in acute respiratory distress syndrome? – RESPIRE

ARDS, as clinically defined, includes patients with a wide range of underlying biologic processes, and the identification of physiologic, clinical, and biologic characteristics that define ARDS subpopulations may add value to determining prognosis and predicting response to treatments. However, there is currently no consensus on the most appropriate approach to understand ARDS heterogeneity, and important gaps in knowledge remain on how more personalized and molecularly targeted therapeutic approaches should be developed for ARDS.
The translational RESPIRE project aims at filling these gaps with its unique strengths that combine precise mechanistic investigations of the lung-protective effects of sevoflurane and clinical application through the identification of a treatable trait (namely, plasma sRAGE as a surrogate marker of lung epithelial permeability) that could predict better therapeutic response to inhaled sevoflurane in patients with ARDS. Beyond these original objectives, other novelties of the RESPIRE project lie in its methodology that combines:
- thorough in vitro evaluation, using multiple AEC lines (including primary human alveolar epithelial cells) of the effects of sevoflurane on RAGE-mediated epithelial activation of the Rho/ROCK pathway and actin cytoskeletal arrangement that may subsequently lead to decreased alveolar epithelial barrier permeability, as assessed by modern and validated methods such as the electric cell-substrate impedance sensing (ECIS) and the XPert assays, among other techniques,
- in vitro and in silico investigations of the effects of sevoflurane on lung epithelial permeability via its potential interaction with RAGE-ligand binding domain, in vivo validation in three mouse models that test the main septic and sterile causes of clinical ARDS, including the use of RAGE-/- mice,
- clinical translation using biological samples and chest radiographs from patients enrolled in a large multicenter randomized clinical trial (RCT) comparing inhaled sedation with sevoflurane to intravenous sedation with propofol (SESAR trial, ClinicalTrials.gov Identifier: NCT04235608),
- and the prospect of developing a point-of-care (POC) assay for plasma sRAGE through an industrial collaboration to be tested as a predictive and prognostic-enrichment method in future trials of personalized therapies for ARDS.

The progress of the RESPIRE project to date, in accordance with our forecasted planning, allows us to report the following outstanding results:
- Detailed description of the kinetics over 24 hours of the effects of sterile (cytomix) and septic (LPS) aggression on alveolar epithelial cells in vitro:
o Cell viability and toxicity
o Function (ECIS, fluid transport) and integrity of the epithelial barrier (microscopy)
o mRNA (RT-qPCR) and protein expression (WB quantification and immunofluorescence localization) of key effectors of epithelial barrier integrity and function: Tight (ZO-1/CLDN-4) and adherens junctions (E-cadherin), cytoskeleton (actin), epithelial channels (ENaC, Na-K-ATPase, AQP5), RhoA-ROCK and RAGE signaling pathways, secretion of inflammatory mediators
- Significant progress in the collection of biological samples and radiographic data from patients included in the SESAR trial.

The conduct of the RESPIRE project significantly strengthens our participation in the research theme on the pulmonary effects of sevoflurane.
This is already reflected in several actions of valorization (communications during national and international conferences, scientific publications in international peer-reviewed journals) and a net increase of our attractiveness for Masters or Thesis program students.

Scientific publications:
1. Use of volatile anesthetics for sedation in the ICU after the COVID-19 pandemic: A national survey in France (VOL’ICU 2 study). Blondonnet R, Balde A, Zhai R, Pereira B, Futier E, Bazin JE, Godet T, Constantin JM, Lambert C, Jabaudon M. PLOS One. Under Review.
2. Inhaled sedation in the intensive care unit. Jabaudon M, Zhai R, Blondonnet R, Lenga Ma Bonda W. Anaesth Crit Care Pain Med. 2022. In Press.
3. Design and Rationale of the Sevoflurane for Sedation in Acute Respiratory Distress Syndrome (SESAR) Randomized Controlled Trial. Blondonnet R, Simand LA, Vidal P, Borao L, Bourguignon N, Morand D, Bernard L, Roszyk L, Audard J, Godet T, Monsel A, Garnier M, Quesnel C, Bazin JE, Sapin V, Bastarache JA, Ware LB, Hughes CG, Pandharipande PP, Ely EW, Futier E, Pereira B, Constantin JM, Jabaudon M, On Behalf Of The Sesar Collaborative Group. J Clin Med. 2022 May 16;11(10):2796. doi: 10.3390/jcm11102796.
4. Inhaled Sedation for Invasively Ventilated COVID-19 Patients: A Systematic Review. Landoni G, Belloni O, Russo G, Bonaccorso A, Carà G, Jabaudon M. J Clin Med. 2022 Apr 29;11(9):2500. doi: 10.3390/jcm11092500.
5. Towards a biological definition of ARDS: are treatable traits the solution? Bos LDJ, Laffey JG, Ware LB, Heijnen NFL, Sinha P, Patel B, Jabaudon M, Bastarache JA, McAuley DF, Summers C, Calfee CS, Shankar-Hari M. Intensive Care Med Exp. 2022 Mar 11;10(1):8. doi: 10.1186/s40635-022-00435-w.
6. From preclinical to clinical models of acute respiratory distress syndrome. Zhai R, Lenga Ma Bonda W, Matute-Bello G, Jabaudon M. Signa Vitae 2022. doi : 10.22514/sv.2021.228.
7. Changes in Plasma Soluble Receptor for Advanced Glycation End-Products Are Associated with Survival in Patients with Acute Respiratory Distress Syndrome. Jabaudon M, Pereira B, Laroche E, Roszyk L, Blondonnet R, Audard J, Godet T, Futier E, Bazin JE, Sapin V, Bastarache JA, Ware LB, Constantin JM, On Behalf Of The Live Study Group And The Azurea Network. J Clin Med. 2021 May 12;10(10):2076. doi: 10.3390/jcm10102076.
8. Biomarkers in acute respiratory distress syndrome. Jabaudon M, Blondonnet R, Ware LB. Curr Opin Crit Care. 2021 Feb 1;27(1):46-54. doi: 10.1097/MCC.0000000000000786.

Scientific communications (conferences):
1. Inhaled sedation: When, how and why? e-Day ARDS, ISICEM, 2021.
2. Berlin ARDS definition: an impediment to finding therapies? LIVES ESICM Conference 2021.
3. Inhaled anesthetics may protect the lungs. 41st ISICEM, 2022.
4. Sevoflurane for sedation in ARDS. 49th Meeting of the JSICM, 2022.
5. Inhaled Anesthetics for Sedation in the Intensive Care Unit. Grand Round of the Department of Anesthesia, Vanderbilt University Medical Center, 2022.
6. What do we know so far? (European) Clinical trials on inhaled sedation. INSPiRE-ICU Investigator Meeting, May 2022.
7. Inhaled Anesthetics for Sedation in the Intensive Care Unit. 9th Asia Anesthesia Summit, 2022.

The acute respiratory distress syndrome (ARDS) is a major cause of respiratory failure and death that still lacks specific therapy. Inhaled sevoflurane is an anesthetic agent that may be relevant to processes that depend on the receptor for advanced glycation end-products (RAGE) pathway and contribute to mortality in ARDS, namely epithelial injury, impaired alveolar fluid clearance, and lung alveolar-capillary permeability (TAURA project, funded by ANR/DGOS PRTS 2013). We designed the translational RESPIRE project to test the hypothesis that sevoflurane could be beneficial in ARDS by decreasing RAGE-mediated lung epithelial permeability (mechanistic in vitro, in vivo, in silico studies and analysis of human samples from patients enrolled in a multicenter clinical trial of sevoflurane in ARDS) and that plasma soluble RAGE may be used as a treatable trait in patients with ARDS, thus supporting the development of a point-of-care assay for its measurement at the bedside.