PMID- 33588817 OWN - NLM STAT- MEDLINE DCOM- 20210224 LR - 20211204 IS - 1471-2466 (Electronic) IS - 1471-2466 (Linking) VI - 21 IP - 1 DP - 2021 Feb 15 TI - SPAK-p38 MAPK signal pathway modulates claudin-18 and barrier function of alveolar epithelium after hyperoxic exposure. PG - 58 LID - 10.1186/s12890-021-01408-7 [doi] LID - 58 AB - BACKGROUND: Hyperoxia downregulates the tight junction (TJ) proteins of the alveolar epithelium and leads to barrier dysfunction. Previous study has showed that STE20/SPS1-related proline/alanine-rich kinase (SPAK) interferes with the intestinal barrier function in mice. The aim of the present study is to explore the association between SPAK and barrier function in the alveolar epithelium after hyperoxic exposure. METHODS: Hyperoxic acute lung injury (HALI) was induced by exposing mice to > 99% oxygen for 64 h. The mice were randomly allotted into four groups comprising two control groups and two hyperoxic groups with and without SPAK knockout. Mouse alveolar MLE-12 cells were cultured in control and hyperoxic conditions with or without SPAK knockdown. Transepithelial electric resistance and transwell monolayer permeability were measured for each group. In-cell western assay was used to screen the possible mechanism of p-SPAK being induced by hyperoxia. RESULTS: Compared with the control group, SPAK knockout mice had a lower protein level in the bronchoalveolar lavage fluid in HALI, which was correlated with a lower extent of TJ disruption according to transmission electron microscopy. Hyperoxia down-regulated claudin-18 in the alveolar epithelium, which was alleviated in SPAK knockout mice. In MLE-12 cells, hyperoxia up-regulated phosphorylated-SPAK by reactive oxygen species (ROS), which was inhibited by indomethacin. Compared with the control group, SPAK knockdown MLE-12 cells had higher transepithelial electrical resistance and lower transwell monolayer permeability after hyperoxic exposure. The expression of claudin-18 was suppressed by hyperoxia, and down-regulation of SPAK restored the expression of claudin-18. The process of SPAK suppressing the expression of claudin-18 and impairing the barrier function was mediated by p38 mitogen-activated protein kinase (MAPK). CONCLUSIONS: Hyperoxia up-regulates the SPAK-p38 MAPK signal pathway by ROS, which disrupts the TJ of the alveolar epithelium by suppressing the expression of claudin-18. The down-regulation of SPAK attenuates this process and protects the alveolar epithelium against the barrier dysfunction induced by hyperoxia. FAU - Shen, Chih-Hao AU - Shen CH AD - Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, No. 325, Section 2, Cheng-Gong Rd, Neihu 114, Taipei, Taiwan. AD - Graduate Institute of Aerospace and Undersea Medicine, National Defense Medical Center, Taipei, Taiwan. FAU - Lin, Jr-Yu AU - Lin JY AD - Graduate Institute of Aerospace and Undersea Medicine, National Defense Medical Center, Taipei, Taiwan. FAU - Lu, Cheng-Yo AU - Lu CY AD - Graduate Institute of Aerospace and Undersea Medicine, National Defense Medical Center, Taipei, Taiwan. FAU - Yang, Sung-Sen AU - Yang SS AD - Division of Nephrology, Department of Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan. FAU - Peng, Chung-Kan AU - Peng CK AD - Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, No. 325, Section 2, Cheng-Gong Rd, Neihu 114, Taipei, Taiwan. FAU - Huang, Kun-Lun AU - Huang KL AD - Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, No. 325, Section 2, Cheng-Gong Rd, Neihu 114, Taipei, Taiwan. kun@mail.ndmctsgh.edu.tw. AD - Graduate Institute of Aerospace and Undersea Medicine, National Defense Medical Center, Taipei, Taiwan. kun@mail.ndmctsgh.edu.tw. AD - Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan. kun@mail.ndmctsgh.edu.tw. LA - eng GR - MOST 105-2314-B-016-003/Ministry of Science and Technology, Taiwan/ GR - TSGH-E-110200/Tri-Service General Hospital/ GR - TSGH-E-109228/Tri-Service General Hospital/ GR - TSGH-E-109228/Tri-Service General Hospital/ GR - TSGH-C106-069/Tri-Service General Hospital/ GR - MAB-109-019/Ministry of National Defense-Medical Affairs Bureau/ GR - MAB-106-015/Ministry of National Defense-Medical Affairs Bureau/ PT - Journal Article DEP - 20210215 PL - England TA - BMC Pulm Med JT - BMC pulmonary medicine JID - 100968563 RN - 0 (Claudins) RN - 0 (Cldn18 protein, mouse) RN - 0 (Reactive Oxygen Species) RN - EC 2.7.1.- (Stk39 protein, mouse) RN - EC 2.7.11.1 (Protein Serine-Threonine Kinases) RN - EC 2.7.11.24 (p38 Mitogen-Activated Protein Kinases) SB - IM MH - Acute Lung Injury/*metabolism/pathology MH - Alveolar Epithelial Cells/*metabolism/ultrastructure MH - Animals MH - Bronchoalveolar Lavage Fluid/chemistry MH - Claudins/*genetics/metabolism MH - Disease Models, Animal MH - Gene Expression Regulation MH - Gene Knockdown Techniques MH - Hyperoxia/*metabolism/pathology MH - Mice MH - Mice, Knockout MH - Mice, Transgenic MH - Microscopy, Electron, Transmission MH - Permeability MH - Protein Serine-Threonine Kinases/*genetics/metabolism MH - Pulmonary Alveoli/*metabolism/ultrastructure MH - Reactive Oxygen Species/metabolism MH - Signal Transduction MH - Tight Junctions/*metabolism/ultrastructure MH - p38 Mitogen-Activated Protein Kinases/*metabolism PMC - PMC7885562 OTO - NOTNLM OT - Alveolar epithelium OT - Claudin-18 OT - Hyperoxia OT - STE20/SPS1-related proline/alanine-rich kinase OT - p38 MAPK COIS- The authors declare that they have no competing interests related to this publication. EDAT- 2021/02/17 06:00 MHDA- 2021/02/25 06:00 PMCR- 2021/02/15 CRDT- 2021/02/16 05:43 PHST- 2020/11/01 00:00 [received] PHST- 2021/01/11 00:00 [accepted] PHST- 2021/02/16 05:43 [entrez] PHST- 2021/02/17 06:00 [pubmed] PHST- 2021/02/25 06:00 [medline] PHST- 2021/02/15 00:00 [pmc-release] AID - 10.1186/s12890-021-01408-7 [pii] AID - 1408 [pii] AID - 10.1186/s12890-021-01408-7 [doi] PST - epublish SO - BMC Pulm Med. 2021 Feb 15;21(1):58. doi: 10.1186/s12890-021-01408-7.