GPR68 Mediates Lung Endothelial Dysfunction Caused by Bacterial Inflammation and Tissue Acidification

Tissue acidification resulting from dysregulated cellular bioenergetics accompanies various inflammatory states. GPR68, along with other members of proton-sensing G protein-coupled receptors, responds to extracellular acidification and has been implicated in chronic inflammation-related diseases suc...

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Main Authors: Pratap Karki, Yunbo Ke, Chenou Zhang, Kamoltip Promnares, Yue Li, Charles H. Williams, Charles C. Hong, Konstantin G. Birukov, Anna A. Birukova
Format: Article
Language:English
Published: MDPI AG 2024-12-01
Series:Cells
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Online Access:https://www.mdpi.com/2073-4409/13/24/2125
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author Pratap Karki
Yunbo Ke
Chenou Zhang
Kamoltip Promnares
Yue Li
Charles H. Williams
Charles C. Hong
Konstantin G. Birukov
Anna A. Birukova
author_facet Pratap Karki
Yunbo Ke
Chenou Zhang
Kamoltip Promnares
Yue Li
Charles H. Williams
Charles C. Hong
Konstantin G. Birukov
Anna A. Birukova
author_sort Pratap Karki
collection DOAJ
description Tissue acidification resulting from dysregulated cellular bioenergetics accompanies various inflammatory states. GPR68, along with other members of proton-sensing G protein-coupled receptors, responds to extracellular acidification and has been implicated in chronic inflammation-related diseases such as ischemia, cancer, and colitis. The present study examined the role of extracellular acidification on human pulmonary endothelial cell (EC) permeability and inflammatory status per se and investigated potential synergistic effects of acidosis on endothelial dysfunction caused by bacterial lipopolysaccharide (LPS, <i>Klebsiella pneumoniae</i>). Results showed that medium acidification to pH 6.5 caused a delayed increase in EC permeability illustrated by a decrease in transendothelial electrical resistance and loss of continuous VE-cadherin immunostaining at cell junctions. Likewise, acidic pH induced endothelial inflammation reflected by increased mRNA and protein expression of EC adhesion molecules VCAM-1 and ICAM-1, upregulated mRNA transcripts of tumor necrosis factor-α, IL-6, IL-8, IL-1β, and CXCL5, and increased secretion of ICAM-1, IL-6, and IL-8 in culture medium monitored by ELISA. Among the GPCRs tested, acidic pH selectively increased mRNA and protein expression of GPR68, and only the GPR68-specific small molecule inhibitor OGM-8345 rescued acidosis-induced endothelial permeability and inflammation. Furthermore, acidic pH exacerbated LPS-induced endothelial permeability and inflammatory response in cultured lung macrovascular as well as microvascular endothelial cells. These effects were suppressed by OGM-8345 in both EC types. Altogether, these results suggest that GPR68 is a critical mediator of acidic pH-induced dysfunction of human pulmonary vascular endothelial cells and mediates the augmenting effect of tissue acidification on LPS-induced endothelial cell injury.
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spelling doaj-art-bdb72c46e1d742d3908f94c4d5ba87e92025-08-20T02:53:28ZengMDPI AGCells2073-44092024-12-011324212510.3390/cells13242125GPR68 Mediates Lung Endothelial Dysfunction Caused by Bacterial Inflammation and Tissue AcidificationPratap Karki0Yunbo Ke1Chenou Zhang2Kamoltip Promnares3Yue Li4Charles H. Williams5Charles C. Hong6Konstantin G. Birukov7Anna A. Birukova8Division of Pulmonary and Critical Care, Department of Medicine, UMSOM Lung Biology Program, University of Maryland School of Medicine, 20 Penn Street, HSF-2, Room S143, Baltimore, MD 21201, USADepartment of Anesthesiology, University of Maryland School of Medicine, Baltimore, MD 21201, USADivision of Pulmonary and Critical Care, Department of Medicine, UMSOM Lung Biology Program, University of Maryland School of Medicine, 20 Penn Street, HSF-2, Room S143, Baltimore, MD 21201, USADepartment of Anesthesiology, University of Maryland School of Medicine, Baltimore, MD 21201, USADivision of Pulmonary and Critical Care, Department of Medicine, UMSOM Lung Biology Program, University of Maryland School of Medicine, 20 Penn Street, HSF-2, Room S143, Baltimore, MD 21201, USADivision of Cardiovascular Medicine, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USADivision of Cardiovascular Medicine, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USADepartment of Anesthesiology, University of Maryland School of Medicine, Baltimore, MD 21201, USADivision of Pulmonary and Critical Care, Department of Medicine, UMSOM Lung Biology Program, University of Maryland School of Medicine, 20 Penn Street, HSF-2, Room S143, Baltimore, MD 21201, USATissue acidification resulting from dysregulated cellular bioenergetics accompanies various inflammatory states. GPR68, along with other members of proton-sensing G protein-coupled receptors, responds to extracellular acidification and has been implicated in chronic inflammation-related diseases such as ischemia, cancer, and colitis. The present study examined the role of extracellular acidification on human pulmonary endothelial cell (EC) permeability and inflammatory status per se and investigated potential synergistic effects of acidosis on endothelial dysfunction caused by bacterial lipopolysaccharide (LPS, <i>Klebsiella pneumoniae</i>). Results showed that medium acidification to pH 6.5 caused a delayed increase in EC permeability illustrated by a decrease in transendothelial electrical resistance and loss of continuous VE-cadherin immunostaining at cell junctions. Likewise, acidic pH induced endothelial inflammation reflected by increased mRNA and protein expression of EC adhesion molecules VCAM-1 and ICAM-1, upregulated mRNA transcripts of tumor necrosis factor-α, IL-6, IL-8, IL-1β, and CXCL5, and increased secretion of ICAM-1, IL-6, and IL-8 in culture medium monitored by ELISA. Among the GPCRs tested, acidic pH selectively increased mRNA and protein expression of GPR68, and only the GPR68-specific small molecule inhibitor OGM-8345 rescued acidosis-induced endothelial permeability and inflammation. Furthermore, acidic pH exacerbated LPS-induced endothelial permeability and inflammatory response in cultured lung macrovascular as well as microvascular endothelial cells. These effects were suppressed by OGM-8345 in both EC types. Altogether, these results suggest that GPR68 is a critical mediator of acidic pH-induced dysfunction of human pulmonary vascular endothelial cells and mediates the augmenting effect of tissue acidification on LPS-induced endothelial cell injury.https://www.mdpi.com/2073-4409/13/24/2125acidosisendothelial permeabilityinflammationLPSGPR68OGM-8345
spellingShingle Pratap Karki
Yunbo Ke
Chenou Zhang
Kamoltip Promnares
Yue Li
Charles H. Williams
Charles C. Hong
Konstantin G. Birukov
Anna A. Birukova
GPR68 Mediates Lung Endothelial Dysfunction Caused by Bacterial Inflammation and Tissue Acidification
Cells
acidosis
endothelial permeability
inflammation
LPS
GPR68
OGM-8345
title GPR68 Mediates Lung Endothelial Dysfunction Caused by Bacterial Inflammation and Tissue Acidification
title_full GPR68 Mediates Lung Endothelial Dysfunction Caused by Bacterial Inflammation and Tissue Acidification
title_fullStr GPR68 Mediates Lung Endothelial Dysfunction Caused by Bacterial Inflammation and Tissue Acidification
title_full_unstemmed GPR68 Mediates Lung Endothelial Dysfunction Caused by Bacterial Inflammation and Tissue Acidification
title_short GPR68 Mediates Lung Endothelial Dysfunction Caused by Bacterial Inflammation and Tissue Acidification
title_sort gpr68 mediates lung endothelial dysfunction caused by bacterial inflammation and tissue acidification
topic acidosis
endothelial permeability
inflammation
LPS
GPR68
OGM-8345
url https://www.mdpi.com/2073-4409/13/24/2125
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