1
|
Gamo S, Tamada T, Murakami K, Muramatsu S, Aritake H, Nara M, Kazama I, Okazaki T, Sugiura H, Ichinose M. TLR7 agonist attenuates acetylcholine-induced, Ca 2+ -dependent ionic currents in swine tracheal submucosal gland cells. Exp Physiol 2018; 103:1543-1559. [PMID: 30194882 DOI: 10.1113/ep087221] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Accepted: 09/04/2018] [Indexed: 01/17/2023]
Abstract
NEW FINDINGS What is the central question of this study? Does Toll-like receptor 7 (TLR7) have any direct effects on Ca2+ -dependent physiological function of tracheal submucosal gland cells? What is the main finding and its importance? TLR7 is co-localized with SERCA2 in tracheal submucosal gland cells and causes a rapid attenuation of acetylcholine (ACh)-induced, Ca2+ -dependent ionic currents through the activation of SERCA2-dependent Ca2+ clearance. TLR7 is abundantly expressed in the airways of both swine and healthy human subjects, but is significantly downregulated in chronic obstructive pulmonary disease (COPD) airways. These findings suggest that a dysfunction of TLR7 in COPD removes the brake on ACh-induced serous secretion during viral infections, resulting in prolonged airway hypersecretion, and that it is one of the triggers of COPD exacerbations. ABSTRACT Airway surface fluids are mainly secreted from submucosal glands (SMGs) and play important roles in the defence of airways via the activation of mucociliary transport. Toll-like receptor 7 (TLR7) recognizes and eliminates single stranded RNA (ssRNA) viruses through the induction of innate immunity. However, there is no obvious connection between TLR7 and mucus secretion, aside from TLR7 recognizing ssRNA viruses, which are often associated with airway hypersecretion in chronic obstructive pulmonary disease (COPD). Here, we investigated whether TLR7 has any direct effects on the Ca2+ -dependent physiological function of tracheal SMG cells. Patch-clamp analyses revealed that TLR7 ligand inhibited the acetylcholine (ACh)-induced ionic currents in isolated tracheal SMG cells. Intracellular calcium assays and pharmacological analyses revealed that TLR7 attenuated the transient rises in the intracellular calcium concentration evoked by ACh by activating sarco/endoplasmic reticulum Ca2+ -ATPase 2 (SERCA2). Immunofluorescence staining and immunohistochemical staining revealed that TLR7 was co-localized with SERCA2. These findings suggest that the activation of TLR7 during viral infections contributes to the rapid attenuation of ACh-induced ionic currents through an increase in SERCA2-dependent Ca2+ clearance in healthy airway SMG cells. Our study also revealed that TLR7 expression was significantly downregulated in COPD airways. Based on these findings, we speculate that a dysfunction of TLR7 may not only have an adverse effect on the elimination of these viruses but also remove the brake on ACh-induced serous secretion, resulting in prolonged hypersecretion and acting as one of the triggers of COPD exacerbations.
Collapse
Affiliation(s)
- Shunichi Gamo
- Department of Respiratory Medicine, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi 980-8574, Aoba-ku, Sendai, Japan
| | - Tsutomu Tamada
- Department of Respiratory Medicine, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi 980-8574, Aoba-ku, Sendai, Japan
| | - Koji Murakami
- Department of Respiratory Medicine, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi 980-8574, Aoba-ku, Sendai, Japan
| | - Soshi Muramatsu
- Department of Respiratory Medicine, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi 980-8574, Aoba-ku, Sendai, Japan
| | - Hidemi Aritake
- Department of Respiratory Medicine, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi 980-8574, Aoba-ku, Sendai, Japan
| | - Masayuki Nara
- Clinical Research, Innovation and Education Center, Tohoku University Hospital, 1-1 Seiryo-machi, Aoba-ku, Sendai, Japan
| | - Itsuro Kazama
- Miyagi University, School of Nursing, 1-1 Gakuen, Taiwa-cho, Kurokawa-gun, Miyagi, 981-3298, Japan
| | - Tatsuma Okazaki
- Department of Respiratory Medicine, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi 980-8574, Aoba-ku, Sendai, Japan
| | - Hisatoshi Sugiura
- Department of Respiratory Medicine, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi 980-8574, Aoba-ku, Sendai, Japan
| | - Masakazu Ichinose
- Department of Respiratory Medicine, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi 980-8574, Aoba-ku, Sendai, Japan
| |
Collapse
|
2
|
Bolnick AD, Bolnick JM, Kohan-Ghadr HR, Kilburn BA, Hertz M, Dai J, Drewlo S, Armant DR. Nifedipine Prevents Apoptosis of Alcohol-Exposed First-Trimester Trophoblast Cells. Alcohol Clin Exp Res 2017; 42:53-60. [PMID: 29048755 DOI: 10.1111/acer.13534] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2017] [Accepted: 10/12/2017] [Indexed: 11/30/2022]
Abstract
BACKGROUND Maternal alcohol abuse leading to fetal alcohol spectrum disorder (FASD) includes fetal growth restriction (FGR). Ethanol (EtOH) induces apoptosis of human placental trophoblast cells, possibly disrupting placentation and contributing to FGR in FASD. EtOH facilitates apoptosis in several embryonic tissues, including human trophoblasts, by raising intracellular Ca2+ . We previously found that acute EtOH exposure increases trophoblast apoptosis due to signaling from both intracellular and extracellular Ca2+ . Therefore, nifedipine, a Ca2+ channel blocker that is commonly administered to treat preeclampsia and preterm labor, was evaluated for cytoprotective properties in trophoblast cells exposed to alcohol. METHODS Human first-trimester chorionic villous explants and the human trophoblast cell line HTR-8/SVneo (HTR) were pretreated with 12.5 to 50 nM of the Ca2+ channel blocker nifedipine for 1 hour before exposure to 50 mM EtOH for an additional hour. Intracellular Ca2+ concentrations were monitored in real time by epifluorescence microscopy, using fluo-4-AM. Apoptosis was assessed by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL), accumulation of cytoplasmic cytochrome c, and cleavage rates of caspase 3 and caspase 9. RESULTS The increase in intracellular Ca2+ upon exposure to EtOH in both villous explants and HTR cells was completely blocked (p < 0.05) when pretreated with nifedipine, accompanied by inhibition of EtOH-induced release of cytochrome c, caspase activities, and TUNEL. CONCLUSIONS This study indicates that nifedipine can interrupt the apoptotic pathway downstream of EtOH exposure and could provide a novel strategy for future interventions in women with fetuses at risk for FASD.
Collapse
Affiliation(s)
- Alan D Bolnick
- Departments of Obstetrics & Gynecology, Wayne State University School of Medicine, Detroit, Michigan
| | - Jay M Bolnick
- Departments of Obstetrics & Gynecology, Wayne State University School of Medicine, Detroit, Michigan
| | - Hamid-Reza Kohan-Ghadr
- Departments of Obstetrics & Gynecology, Wayne State University School of Medicine, Detroit, Michigan
| | - Brian A Kilburn
- Departments of Obstetrics & Gynecology, Wayne State University School of Medicine, Detroit, Michigan
| | - Michael Hertz
- Departments of Obstetrics & Gynecology, Wayne State University School of Medicine, Detroit, Michigan
| | - Jing Dai
- Departments of Obstetrics & Gynecology, Wayne State University School of Medicine, Detroit, Michigan
| | - Sascha Drewlo
- Departments of Obstetrics & Gynecology, Wayne State University School of Medicine, Detroit, Michigan
| | - D Randall Armant
- Departments of Obstetrics & Gynecology, Wayne State University School of Medicine, Detroit, Michigan.,Anatomy& Cell Biology, Wayne State University School of Medicine, Detroit, Michigan
| |
Collapse
|
3
|
Lee RJ, Foskett JK. Ca²⁺ signaling and fluid secretion by secretory cells of the airway epithelium. Cell Calcium 2014; 55:325-36. [PMID: 24703093 DOI: 10.1016/j.ceca.2014.02.001] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Revised: 01/31/2014] [Accepted: 02/01/2014] [Indexed: 11/24/2022]
Abstract
Cytoplasmic Ca(2+) is a master regulator of airway physiology; it controls fluid, mucus, and antimicrobial peptide secretion, ciliary beating, and smooth muscle contraction. The focus of this review is on the role of cytoplasmic Ca(2+) in fluid secretion by airway exocrine secretory cells. Airway submucosal gland serous acinar cells are the primary fluid secreting cell type of the cartilaginous conducting airways, and this review summarizes the current state of knowledge of the molecular mechanisms of serous cell ion transport, with an emphasis on their regulation by intracellular Ca(2+). Many neurotransmitters that regulate secretion from serous acinar cells utilize Ca(2+) as a second messenger. Changes in intracellular Ca(2+) concentration regulate the activities of ion transporters and channels involved in transepithelial ion transport and fluid secretion, including Ca(2+)-activated K(+) channels and Cl(-) channels. We also review evidence of interactions of Ca(2+) signaling with other signaling pathways (cAMP, NO) that impinge upon different ion transport pathways, including the cAMP/PKA-activated cystic fibrosis (CF) transmembrane conductance regulator (CFTR) anion channel. A better understanding of Ca(2+) signaling and its targets in airway fluid secretion may identify novel strategies to intervene in airway diseases, for example to enhance fluid secretion in CF airways.
Collapse
Affiliation(s)
- Robert J Lee
- Department of Otorhinolaryngology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States
| | - J Kevin Foskett
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States; Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States.
| |
Collapse
|
4
|
Muramatsu S, Tamada T, Nara M, Murakami K, Kikuchi T, Kanehira M, Maruyama Y, Ebina M, Nukiwa T, Ichinose M. Flagellin/TLR5 signaling potentiates airway serous secretion from swine tracheal submucosal glands. Am J Physiol Lung Cell Mol Physiol 2013; 305:L819-30. [PMID: 24097563 DOI: 10.1152/ajplung.00053.2013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Airway serous secretion is essential for the maintenance of mucociliary transport in airway mucosa, which is responsible for the upregulation of mucosal immunity. Although there are many articles concerning the importance of Toll-like receptors (TLRs) in airway immune systems, the direct relationship between TLRs and airway serous secretion has not been well investigated. Here, we focused on whether TLR5 ligand flagellin, which is one of the components of Pseudomonas aeruginosa, is involved in the upregulation of airway serous secretion. Freshly isolated swine tracheal submucosal gland cells were prepared, and the standard patch-clamp technique was applied for measurements of the whole cell ionic responses of these cells. Flagellin showed potentiating effects on these oscillatory currents induced by physiologically relevant low doses of acetylcholine (ACh) in a dose-dependent manner. These potentiating effects were TLR5 dependent but TLR4 independent. Both nitric oxide (NO) synthase inhibitors and cGMP-dependent protein kinase (cGK) inhibitors abolished these flagellin-induced potentiating effects. Furthermore, TLR5 was abundantly expressed on tracheal submucosal glands. Flagellin/TLR5 signaling further accelerated the intracellular NO synthesis induced by ACh. These findings suggest that TLR5 takes part in the airway mucosal defense systems as a unique endogenous potentiator of airway serous secretions and that NO/cGMP/cGK signaling is involved in this rapid potentiation by TLR5 signaling.
Collapse
Affiliation(s)
- Soshi Muramatsu
- Dept. of Respiratory Medicine, Tohoku Univ. Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai 980-8574, JAPAN.
| | | | | | | | | | | | | | | | | | | |
Collapse
|