Persistent hypoxia promotes myofibroblast differentiation via GPR‐81 and differential regulation of LDH isoenzymes in normal and idiopathic pulmonary fibrosis fibroblasts
Abstract Hypoxia, a state of insufficient oxygen availability, promotes cellular lactate production. Lactate levels are increased in lungs from patients with idiopathic pulmonary fibrosis (IPF), a disease characterized by excessive scar formation, and lactate is implicated in the pathobiology of lun...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
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Wiley
2023-09-01
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| Series: | Physiological Reports |
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| Online Access: | https://doi.org/10.14814/phy2.15759 |
| _version_ | 1797364854160359424 |
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| author | Richard S. Nho Cami Rice Jayendra Prasad Hannah Bone Laszlo Farkas Mauricio Rojas Jeffrey C. Horowitz |
| author_facet | Richard S. Nho Cami Rice Jayendra Prasad Hannah Bone Laszlo Farkas Mauricio Rojas Jeffrey C. Horowitz |
| author_sort | Richard S. Nho |
| collection | DOAJ |
| description | Abstract Hypoxia, a state of insufficient oxygen availability, promotes cellular lactate production. Lactate levels are increased in lungs from patients with idiopathic pulmonary fibrosis (IPF), a disease characterized by excessive scar formation, and lactate is implicated in the pathobiology of lung fibrosis. However, the mechanisms underlying the effects of hypoxia and lactate on fibroblast phenotype are poorly understood. We exposed normal and IPF lung fibroblasts to persistent hypoxia and found that increased lactate generation by IPF fibroblasts was driven by the FoxM1‐dependent increase of lactate dehydrogenase A (LDHA) coupled with decreased LDHB that was not observed in normal lung fibroblasts. Importantly, hypoxia reduced α‐smooth muscle actin (α‐SMA) expression in normal fibroblasts but had no significant impact on this marker of differentiation in IPF fibroblasts. Treatment of control and IPF fibroblasts with TGF‐β under hypoxic conditions did not significantly change LDHA or LDHB expression. Surprisingly, lactate directly induced the differentiation of normal, but not IPF fibroblasts under hypoxic conditions. Moreover, while expression of GPR‐81, a G‐protein‐coupled receptor that binds extracellular lactate, was increased by hypoxia in both normal and IPF fibroblasts, its inhibition or silencing only suppressed lactate‐mediated differentiation in normal fibroblasts. These studies show that hypoxia differentially affects normal and fibrotic fibroblasts, promoting increased lactate generation by IPF fibroblasts through regulation of the LDHA/LDHB ratio and promoting normal lung fibroblast responsiveness to lactate through GPR‐81. This supports a novel paradigm in which lactate may serve as a paracrine intercellular signal in oxygen‐deficient microenvironments. |
| first_indexed | 2024-03-08T16:42:04Z |
| format | Article |
| id | doaj.art-5a709e79e4994df8a6a0a8536a2e0f4a |
| institution | Directory Open Access Journal |
| issn | 2051-817X |
| language | English |
| last_indexed | 2024-03-08T16:42:04Z |
| publishDate | 2023-09-01 |
| publisher | Wiley |
| record_format | Article |
| series | Physiological Reports |
| spelling | doaj.art-5a709e79e4994df8a6a0a8536a2e0f4a2024-01-05T09:46:30ZengWileyPhysiological Reports2051-817X2023-09-011117n/an/a10.14814/phy2.15759Persistent hypoxia promotes myofibroblast differentiation via GPR‐81 and differential regulation of LDH isoenzymes in normal and idiopathic pulmonary fibrosis fibroblastsRichard S. Nho0Cami Rice1Jayendra Prasad2Hannah Bone3Laszlo Farkas4Mauricio Rojas5Jeffrey C. Horowitz6Division of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine, The Davis Heart and Lung Research Institute The Ohio State University Columbus Ohio USADivision of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine, The Davis Heart and Lung Research Institute The Ohio State University Columbus Ohio USADivision of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine, The Davis Heart and Lung Research Institute The Ohio State University Columbus Ohio USADivision of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine, The Davis Heart and Lung Research Institute The Ohio State University Columbus Ohio USADivision of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine, The Davis Heart and Lung Research Institute The Ohio State University Columbus Ohio USADivision of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine, The Davis Heart and Lung Research Institute The Ohio State University Columbus Ohio USADivision of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine, The Davis Heart and Lung Research Institute The Ohio State University Columbus Ohio USAAbstract Hypoxia, a state of insufficient oxygen availability, promotes cellular lactate production. Lactate levels are increased in lungs from patients with idiopathic pulmonary fibrosis (IPF), a disease characterized by excessive scar formation, and lactate is implicated in the pathobiology of lung fibrosis. However, the mechanisms underlying the effects of hypoxia and lactate on fibroblast phenotype are poorly understood. We exposed normal and IPF lung fibroblasts to persistent hypoxia and found that increased lactate generation by IPF fibroblasts was driven by the FoxM1‐dependent increase of lactate dehydrogenase A (LDHA) coupled with decreased LDHB that was not observed in normal lung fibroblasts. Importantly, hypoxia reduced α‐smooth muscle actin (α‐SMA) expression in normal fibroblasts but had no significant impact on this marker of differentiation in IPF fibroblasts. Treatment of control and IPF fibroblasts with TGF‐β under hypoxic conditions did not significantly change LDHA or LDHB expression. Surprisingly, lactate directly induced the differentiation of normal, but not IPF fibroblasts under hypoxic conditions. Moreover, while expression of GPR‐81, a G‐protein‐coupled receptor that binds extracellular lactate, was increased by hypoxia in both normal and IPF fibroblasts, its inhibition or silencing only suppressed lactate‐mediated differentiation in normal fibroblasts. These studies show that hypoxia differentially affects normal and fibrotic fibroblasts, promoting increased lactate generation by IPF fibroblasts through regulation of the LDHA/LDHB ratio and promoting normal lung fibroblast responsiveness to lactate through GPR‐81. This supports a novel paradigm in which lactate may serve as a paracrine intercellular signal in oxygen‐deficient microenvironments.https://doi.org/10.14814/phy2.15759G protein‐coupled receptor‐81 (GPR‐81)hypoxiaidiopathic pulmonary fibrosis (IPF)lactate dehydrogenaseα‐smooth muscle actin (α‐SMA) |
| spellingShingle | Richard S. Nho Cami Rice Jayendra Prasad Hannah Bone Laszlo Farkas Mauricio Rojas Jeffrey C. Horowitz Persistent hypoxia promotes myofibroblast differentiation via GPR‐81 and differential regulation of LDH isoenzymes in normal and idiopathic pulmonary fibrosis fibroblasts Physiological Reports G protein‐coupled receptor‐81 (GPR‐81) hypoxia idiopathic pulmonary fibrosis (IPF) lactate dehydrogenase α‐smooth muscle actin (α‐SMA) |
| title | Persistent hypoxia promotes myofibroblast differentiation via GPR‐81 and differential regulation of LDH isoenzymes in normal and idiopathic pulmonary fibrosis fibroblasts |
| title_full | Persistent hypoxia promotes myofibroblast differentiation via GPR‐81 and differential regulation of LDH isoenzymes in normal and idiopathic pulmonary fibrosis fibroblasts |
| title_fullStr | Persistent hypoxia promotes myofibroblast differentiation via GPR‐81 and differential regulation of LDH isoenzymes in normal and idiopathic pulmonary fibrosis fibroblasts |
| title_full_unstemmed | Persistent hypoxia promotes myofibroblast differentiation via GPR‐81 and differential regulation of LDH isoenzymes in normal and idiopathic pulmonary fibrosis fibroblasts |
| title_short | Persistent hypoxia promotes myofibroblast differentiation via GPR‐81 and differential regulation of LDH isoenzymes in normal and idiopathic pulmonary fibrosis fibroblasts |
| title_sort | persistent hypoxia promotes myofibroblast differentiation via gpr 81 and differential regulation of ldh isoenzymes in normal and idiopathic pulmonary fibrosis fibroblasts |
| topic | G protein‐coupled receptor‐81 (GPR‐81) hypoxia idiopathic pulmonary fibrosis (IPF) lactate dehydrogenase α‐smooth muscle actin (α‐SMA) |
| url | https://doi.org/10.14814/phy2.15759 |
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