Arthritis & Rheumatism, Volume 62,
November 2010 Abstract Supplement
Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Atlanta, Georgia November 6-11, 2010.
The Cholinergic Anti-Inflammatory Pathway as a Modulator of Immune Complex-Induced Acute Inflammation.
Vukelic2, Milena, Koo2, Gloria, Salmon1, Jane E.
The "cholinergic antiinflammatory pathway" is a neural mechanism by which the efferent vagus nerve leads to stimulation of nicotinic acetylcholine receptors (nAchR) on immune cells and thereby inhibits their synthesis of proinflammatory mediators in response to innate immune stimuli. Its role in antibody-mediated injury, such as that present in SLE, has not been explored. We hypothesized that ligation of nAChRs would downmodulate C5aR- and FcgR-triggered activation of neutrophils and monocytes and limit immune complex-triggered inflammation. We examined effects of nAChR ligation on in vitro markers of activation related to tissue damage generation of reactive oxygen species (ROS), production of TNFa, IL-6 and expression of adhesion molecule, as well as in vivo effects with the peritoneal Arthus reaction.
Human or mouse (C57/Bl6) neutrophils (PMNs) and human monocytes were incubated with C5a (100nM) or model IC (heat-aggregated IgG) in a presence of cholinergic agonists, acetylcholine (Ach) (10mM), nicotine (1mM) or GTS21 (specific a7nAChR agonist) (1mM), nAchR agonist with a competitive nAchR antagonist meccamylamine, or control medium. ROS was measured by dihydrorhodamine123 by FACS. TNFa, IL-6 levels were analyzed by ELISA. Peritoneal reverse passive Arthus reaction was initiated by injecting OVA i.v. and anti-OVA IgG i.p. After 3hrs PMN recruitment in peritoneal lavage fluid was assessed by FACS.
In human PMN ligation of nAchR with a7nAChR agonist GTS21, Ach (naturally occurring nAchR ligand) or nicotine markedly inhibited C5a-induced ROS generation (vs control, 69±8%,p=0.014; 48±9%, p=0.035; 30±5%, p<0.05, respectively). This effect was partially reversed by nAchR antagonist meccamylamine. Similarly, FcgR-mediated ROS was decreased by nicotine (38±11%; p=0.029) and ROS generation by immune complexes (IC) in a presence of normal human serum, reflecting the synergism between C5aR and FcgR in PMN, was also attenuated (63±14%; p=0.029). Experiments with mouse PMN showed similar results. PMN recruitment to the sites of inflammation in response to C5aR requires upregulation CD11b, another effect inhibited by nicotine (251±46 vs. 139±20; p<0.05). At sites of IC deposition, proinflammatory cytokine release is blunted by nAchR. C5aR-triggered TNFa release by human monocytes was abrogated (9045±4402 vs. 49±10pg/mg). There was a similar, albeit less dramatic, decrease in FcgR-mediated cytokines production (TNFa 45±44%; IL-6 46±2%). In vivo effects of nAChR ligation confirmed our in vitro studies. In the peritoneal Arthus reaction, a single i.p. dose of the nAChR agonist GST21 or nicotine decreased PMN recruitment by 65% (342±50×106 vs. 122±29x 106cell/ml;p<0.05) and by 54% (318±27×106 vs. 144±7×106cell/ml;p<0.05), respectively. In addition, GTS21 decreased TNFa levels in the peritoneal fluid (35±2.4 vs. 23±3.2pg/ml).
Our data show that cholinergic anti-inflammatory pathway modulates responses to elements of the adaptive immune system, FcgR and C5aR. We identified nAchR as a novel target to attenuate release of oxidants, influx of inflammatory cells and generation of injurious cytokines at sites of IC deposition.
To cite this abstract, please use the following information:
Vukelic, Milena, Koo, Gloria, Salmon, Jane E.; The Cholinergic Anti-Inflammatory Pathway as a Modulator of Immune Complex-Induced Acute Inflammation. [abstract]. Arthritis Rheum 2010;62 Suppl 10 :866