Inhibition of IP3R/Ca2+ Dysregulation Protects Mice From Ventilator-Induced Lung Injury via Endoplasmic Reticulum and Mitochondrial Pathways

Front Immunol. 2021 Sep 15:12:729094. doi: 10.3389/fimmu.2021.729094. eCollection 2021.

Abstract

Rationale: Disruption of intracellular calcium (Ca2+) homeostasis is implicated in inflammatory responses. Here we investigated endoplasmic reticulum (ER) Ca2+ efflux through the Inositol 1,4,5-trisphosphate receptor (IP3R) as a potential mechanism of inflammatory pathophysiology in a ventilator-induced lung injury (VILI) mouse model.

Methods: C57BL/6 mice were exposed to mechanical ventilation using high tidal volume (HTV). Mice were pretreated with the IP3R agonist carbachol, IP3R inhibitor 2-aminoethoxydiphenyl borate (2-APB) or the Ca2+ chelator BAPTA-AM. Lung tissues and bronchoalveolar lavage fluid (BALF) were collected to measure Ca2+ concentrations, inflammatory responses and mRNA/protein expression associated with ER stress, NLRP3 inflammasome activation and inflammation. Analyses were conducted in concert with cultured murine lung cell lines.

Results: Lungs from mice subjected to HTV displayed upregulated IP3R expression in ER and mitochondrial-associated-membranes (MAMs), with enhanced formation of MAMs. Moreover, HTV disrupted Ca2+ homeostasis, with increased flux from the ER to the cytoplasm and mitochondria. Administration of carbachol aggravated HTV-induced lung injury and inflammation while pretreatment with 2-APB or BAPTA-AM largely prevented these effects. HTV activated the IRE1α and PERK arms of the ER stress signaling response and induced mitochondrial dysfunction-NLRP3 inflammasome activation in an IP3R-dependent manner. Similarly, disruption of IP3R/Ca2+ in MLE12 and RAW264.7 cells using carbachol lead to inflammatory responses, and stimulated ER stress and mitochondrial dysfunction.

Conclusion: Increase in IP3R-mediated Ca2+ release is involved in the inflammatory pathophysiology of VILI via ER stress and mitochondrial dysfunction. Antagonizing IP3R/Ca2+ and/or maintaining Ca2+ homeostasis in lung tissue represents a prospective treatment approach for VILI.

Keywords: calcium; endoplasmic reticulum stress; inositol 1,4,5-trisphosphate receptor; mitochondrial dysfunction; ventilator-induced lung injury.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis / drug effects
  • Boron Compounds / pharmacology*
  • Calcium / metabolism*
  • Calcium Chelating Agents / pharmacology*
  • Calcium Signaling / drug effects*
  • Carbachol / toxicity
  • Disease Models, Animal
  • Egtazic Acid / analogs & derivatives*
  • Egtazic Acid / pharmacology
  • Endoplasmic Reticulum / drug effects*
  • Endoplasmic Reticulum / metabolism
  • Endoplasmic Reticulum / pathology
  • Endoplasmic Reticulum Stress / drug effects
  • Inflammasomes / metabolism
  • Inflammation Mediators / metabolism
  • Inositol 1,4,5-Trisphosphate Receptors / antagonists & inhibitors*
  • Inositol 1,4,5-Trisphosphate Receptors / metabolism
  • Lung / drug effects*
  • Lung / metabolism
  • Lung / pathology
  • Macrophages / drug effects
  • Macrophages / metabolism
  • Macrophages / pathology
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mitochondria / drug effects*
  • Mitochondria / metabolism
  • Mitochondria / pathology
  • NLR Family, Pyrin Domain-Containing 3 Protein / metabolism
  • RAW 264.7 Cells
  • Ventilator-Induced Lung Injury / metabolism
  • Ventilator-Induced Lung Injury / pathology
  • Ventilator-Induced Lung Injury / prevention & control*

Substances

  • Boron Compounds
  • Calcium Chelating Agents
  • Inflammasomes
  • Inflammation Mediators
  • Inositol 1,4,5-Trisphosphate Receptors
  • NLR Family, Pyrin Domain-Containing 3 Protein
  • Nlrp3 protein, mouse
  • 1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid acetoxymethyl ester
  • Egtazic Acid
  • Carbachol
  • 2-aminoethoxydiphenyl borate
  • Calcium