TY - JOUR
T1 - Nicotine attenuates activation of tissue resident macrophages in the mouse stomach through the β2 nicotinic acetylcholine receptor
AU - Nemethova, Andrea
AU - Michel, Klaus
AU - Gomez-Pinilla, Pedro J.
AU - Boeckxstaens, Guy E.
AU - Schemann, Michael
PY - 2013/11
Y1 - 2013/11
N2 - Background: The cholinergic anti-inflammatory pathway is an endogenous mechanism by which the autonomic nervous system attenuates macrophage activation via nicotinic acetylcholine receptors (nAChR). This concept has however not been demonstrated at a cellular level in intact tissue. To this end, we have studied the effect of nicotine on the activation of resident macrophages in a mouse stomach preparation by means of calcium imaging. Methods: Calcium transients ([Ca2+]i) in resident macrophages were recorded in a mouse stomach preparation containing myenteric plexus and muscle layers by Fluo-4. Activation of macrophages was achieved by focal puff administration of ATP. The effects of nicotine on activation of macrophages were evaluated and the nAChR involved was pharmacologically characterized. The proximity of cholinergic nerves to macrophages was quantified by confocal microscopy. Expression of β2 and α7 nAChR was evaluated by β2 immunohistochemistry and fluorophore-tagged α-bungarotoxin. Results: In 83% of macrophages cholinergic varicose nerve fibers were detected at distances <900nm. The ATP induced [Ca2+]i increase was significantly inhibited in 65% or 55% of macrophages by 100μM or 10μM nicotine, respectively. This inhibitory effect was reversed by the β2 nAChR preferring antagonist dihydro-β-eryhtroidine but not by hexamethonium (non-selective nAChR-antagonist), mecamylamine (α3β4 nAChR-preferring antagonist), α-bungarotoxin or methyllycaconitine (both α7 nAChR-preferring antagonist). Macrophages in the stomach express β2 but not α7 nAChR at protein level, while those in the intestine express both receptor subunits. Conclusion: This study is the first in situ demonstration of an inhibition of macrophage activation by nicotine suggesting functional signaling between cholinergic neurons and macrophages in the stomach. The data suggest that the β2 subunit of the nAChR is critically involved in the nicotine-induced inhibition of these resident macrophages.
AB - Background: The cholinergic anti-inflammatory pathway is an endogenous mechanism by which the autonomic nervous system attenuates macrophage activation via nicotinic acetylcholine receptors (nAChR). This concept has however not been demonstrated at a cellular level in intact tissue. To this end, we have studied the effect of nicotine on the activation of resident macrophages in a mouse stomach preparation by means of calcium imaging. Methods: Calcium transients ([Ca2+]i) in resident macrophages were recorded in a mouse stomach preparation containing myenteric plexus and muscle layers by Fluo-4. Activation of macrophages was achieved by focal puff administration of ATP. The effects of nicotine on activation of macrophages were evaluated and the nAChR involved was pharmacologically characterized. The proximity of cholinergic nerves to macrophages was quantified by confocal microscopy. Expression of β2 and α7 nAChR was evaluated by β2 immunohistochemistry and fluorophore-tagged α-bungarotoxin. Results: In 83% of macrophages cholinergic varicose nerve fibers were detected at distances <900nm. The ATP induced [Ca2+]i increase was significantly inhibited in 65% or 55% of macrophages by 100μM or 10μM nicotine, respectively. This inhibitory effect was reversed by the β2 nAChR preferring antagonist dihydro-β-eryhtroidine but not by hexamethonium (non-selective nAChR-antagonist), mecamylamine (α3β4 nAChR-preferring antagonist), α-bungarotoxin or methyllycaconitine (both α7 nAChR-preferring antagonist). Macrophages in the stomach express β2 but not α7 nAChR at protein level, while those in the intestine express both receptor subunits. Conclusion: This study is the first in situ demonstration of an inhibition of macrophage activation by nicotine suggesting functional signaling between cholinergic neurons and macrophages in the stomach. The data suggest that the β2 subunit of the nAChR is critically involved in the nicotine-induced inhibition of these resident macrophages.
UR - http://www.scopus.com/inward/record.url?scp=84891379869&partnerID=8YFLogxK
U2 - 10.1371/journal.pone.0079264
DO - 10.1371/journal.pone.0079264
M3 - Article
C2 - 24223920
AN - SCOPUS:84891379869
SN - 1932-6203
VL - 8
JO - PLoS ONE
JF - PLoS ONE
IS - 11
M1 - e79264
ER -