• Research Summary
• Cholinergic Regulation of Endothelial Cell Activation in Inflammation and Sepsis
• Regulation of Kidney Ischemia-Reperfusion Injury by Cholinergic Agonists
• The Effects Of Smoking Cessation On Inflammatory Responses
• Identification of Biomarkers Associated with Alcohol Abuse
• Maternal Fetal Medicine Research Program
• Ovarian Cancer Discovery Program

Research Summary

Endothelial cells line the body’s blood vessels to create ‘slippery tubes’ which facilitate the rapid transport of blood throughout the body.  Almost every inflammatory condition is associated with tissue damage caused by excessive and/or sustained endothelial cell activation and immune cell infiltration.  Because most inflammatory diseases involve endothelial cells, the endothelium is a critical target for anti-inflammation strategies.  Dr. Metz’s work focuses on the regulation of inflammation, with an emphasis on endothelial cell activation and immune cell trafficking. More specifically, the laboratory is investigating how the cholinergic anti-inflammatory pathway controls endothelial cell activation and immune cell recruitment to prevent organ injury (e.g. kidney, lung, brain) during inflammation, sepsis, and ischemia-reperfusion injury.  Using several experimental models of inflammation, along with both cellular and molecular approaches, the lab is beginning to unravel how cholinergic agonists and anti-inflammatory mediators regulate endothelial cell and immune cell responses. 

In addition, Dr. Metz oversees the discovery and development of novel diagnostics and therapeutics for human disease by collaborating with clinicians throughout the North Shore-LIJ Health System. Dr. Metz is the Co-Director of the Tissue Donation Program, which provides valuable human specimens for translational disease-oriented research.  As Director of Research for the Maternal Fetal Medicine (MFM) Fellowship Program, Dr. Metz collaborates with Drs. Burton Rochelson, MD and Dawnette Lewis, MD in the Department of Obstetrics-Gynecology (Division of MFM) and the MFM Fellows on research studies using cell-based and experimental models of pre-term labor and pre-eclampsia, inflammatory conditions of pregnancy. Other collaborations within the Health System include: Drs. Barbara Sherry, PhD, Peter Gregersen, MD, and John Lovecchio, MD (Department of Obstetrics and Gynecology) to study early disease markers and genetic risk factors for ovarian cancer; and The Center for Tobacco Control to investigate the effects of smoking cessation on inflammatory responses and to develop improved smoking cessation programs. 
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Cholinergic Regulation of Endothelial Cell Activation in Inflammation and Sepsis

Sepsis, a leading complication of surgery and trauma, is a condition characterized by a systemic inflammatory response (with excessive cytokine production) associated with infection.  Despite numerous advances for the treatment of sepsis, the mortality rate for septic patients is between 20-60%, depending on the severity of their condition. Using experimental models of inflammation and sepsis, we are examining the effects of cholinergic stimulation (through electrical stimulation of the vagus nerve or cholinergic agonists or drugs) on endothelial cell activation and leukocyte trafficking. The endothelium is an important target of anti-inflammation and anti-sepsis strategies (Tracey and Metz, The Comprehensive Treatise on the Endothelium, 2007). The cholinergic anti-inflammatory pathway, originally described by Dr. Kevin Tracey at the Feinstein Institute, is a physiological mechanism that inhibits cytokine production during inflammatory conditions, including sepsis. Electrical stimulation of the efferent vagus nerve, the longest nerve in the body which innervates the heart, stomach, liver, and kidneys, releases the neurotransmitter acetylcholine.  Acetylcholine binds to nicotinic acetylcholine receptors present on macrophages and other cells to suppress cytokine production during inflammation (Metz and Tracey, Nature 2005). Likewise, several cholinergic agonists (e.g. nicotine and GTS-21) can bind to nicotinic acetylcholine receptors to dampen inflammation.  Initial studies by our laboratory revealed that both vagus nerve stimulation and cholinergic agonists (which bind to nicotinic receptors) suppress endothelial cell activation in vitro and in vivo and block leukocyte trafficking during acute inflammation Saeed et al, JEM 2005). In addition to employing experimental models to study the cholinergic regulation of endothelial cell activation, chemokine production, and leukocyte accumulation in various organs (including the brain, kidney, and lungs), we use human endothelial cell cultures to explore how cholinergic agonists control endothelial cell activation and chemokine production.  Current studies focus on the NFκB and STAT3 inflammatory pathways.  Interestingly, nicotine exhibits anti-depressant activity.  Therefore, we are also interested in investigating how cholinergic agonists and anti-depressants regulate endothelial cell activation and inflammatory responses during depression. Our ongoing studies are expected to improve the understanding of how cholinergic signaling controls endothelial cell activation and leukocyte trafficking in vivo.  This work has been funded, in part, by NIH-NIGMS.
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Regulation of Kidney Ischemia-Reperfusion Injury by Cholinergic Agonists

Kidney ischemia reperfusion injury is a leading cause of acute renal failure. The incidence of acute renal failure is increasing. Acute renal failure is common in patients after trauma, hemorrhagic shock, cardiopulmonary bypass surgery, and sepsis. The mortality rate for patients with both acute renal failure and sepsis can be as high as 70%.  Currently, there are no therapeutic agents for preventing or treating acute renal failure.  Using experimental models of renal ischemia-reperfusion injury, we explored the potential role of cholinergic agonists (e.g. nicotine and GTS-21) in protecting against renal ischemia-reperfusion injury.  The advantage of this therapeutic strategy is that it targets numerous inflammatory pathways simultaneously. In collaboration with NSUH Pathologists, Drs. Myron Sussin, MD (retired) and Douglas Charney, MD, we have shown that administration of cholinergic agonists suppress ischemia-induced kidney tissue damage (Yeboah et al, Kidney Int’l 2008).  Our laboratory has characterized the expression of nicotinic acetylcholine receptors, targets of anti-inflammatory cholinergic agonists, within the kidney under normal conditions and following ischemia-reperfusion injury (Yeboah et al, Am J Physiol Renal Physiol 2008).  Our data suggest that cholinergic agonists exert anti-inflammatory effects within the kidney. Current studies are investigating the effects of cholinergic agonist administration on chronic renal damage following ischemia-reperfusion injury, including proteinuria, renal T lymphocyte and macrophage infiltration, and renal fibrosis.  Further ongoing studies are examining the cellular and molecular mechanisms whereby cholinergic agonists protect the kidney from ischemic and inflammatory injury.
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The Effects of Smoking Cessation on Inflammatory Responses

Our laboratory collaborates with the Center for Tobacco Control (part of the North Shore-LIJ Health System) on several projects related to smoking cessation (or quitting smoking).   Our primary interest it to examine the effects of nicotinic acetylcholine receptor agonists, including nicotine and varenicline, used for smoking cessation on inflammatory responses.  In a pilot study funded by the American Heart Association, we examined the effects of quitting smoking on a panel of circulating inflammatory biomarkers associated with cardiovascular disease in ‘at risk’ women during the smoking cessation process (Reichert et al, Chest 2009).  We found significant reductions in several serum inflammatory biomarkers linked to cardiovascular disease over the course of smoking cessation. These observations support the anti-inflammatory role of nicotine.  In addition, they suggest that there are rapid and measurable consequences of quitting smoking on inflammatory biomarkers in women at risk for cardiovascular disease.  Additional, larger studies including diverse smokers seeking to quit smoking will be required to confirm our results.  If confirmed, these changes in ‘measurable milestones’ could serve as motivating factors to assist smokers to quit.  In addition, we are collaborating with Dr. Peter Gregersen, MD, to identify potential genes involved in the addiction to cigarettes and the ability (or inability) to quit smoking.
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Identification of Biomarkers Associated with Alcohol Abuse

Our laboratory is working with Feinstein chemist Yousef Al-Abed, PhD, to develop reliable methods to detect acute and chronic alcohol abuse. Acetaldehye is produced by the body following alcohol intake and we have attempted to generate antibodies specific for biomarkers formed in the presence of acetaldehyde. Ultimately, these antibodies could be used to detect biomarkers of alcohol abuse in the blood following binge drinking or chronic alcohol abuse. This work was funded by NIAAA.
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Maternal Fetal Medicine Research Program

Our laboratory collaborates with clinicians and fellows in the Division of Maternal Fetal Medicine (MFM) in the Department of Obstetrics and Gynecology.  One project is exploring the anti-inflammatory role of magnesium sulfate, a tocolytic agent used to delay pre-term labor.  The precise mechanisms of action of magnesium sulfate in pre-term labor are not completely understood. In collaboration with Dr. Burton Rochelson, MD, we discovered that magnesium sulfate suppressed the activation of human umbilical vein endothelial cells through NFkB (Rochelson et al., J Repro Immunol 2007).  These unexpected observations have important implications in light of recent studies showing that maternal administration of magnesium sulfate is associated with a reduction in cerebral palsy in preterm babies. Current studies in the laboratory are exploring the potential regulation of maternal and fetal inflammation by magnesium sulfate using in vitro and in vivo models. 

Additional studies focus on the modulation of maternal and fetal inflammatory responses associated with pre-eclampsia by the cholinergic anti-inflammatory pathway.  Numerous studies show that smoking is protective against pre-eclampsia, a condition characterized by hypertension and proteinuria in the second trimester of pregnancy.  Pre-eclampsia, often referred to as the septicemia of pregnancy, is characterized by maternal/placental inflammation and can progress to eclampsia, a potentially deadly condition of pregnancy.  While smoking is harmful to both the mother and fetus and should be avoided, based on the anti-inflammatory activities of nicotine (a cholinergic agonist and major component of cigarettes) we hypothesized that nicotine was protective against pre-eclampsia. Our early findings revealed that nicotine and other cholinergic agonists suppress cytokine production by cells isolated from the human placenta through the NFκB pathway (Dowling et al Mol Med 2007).  Further studies focus on exploring the regulation of maternal and fetal inflammation by cholinergic stimulation using experimental models of pre-eclampsia and pre-term labor.

Our laboratory continues to collaborate with Dr. Akoum from Laval University to explore the role of macrophage migration inhibitory factor (MIF) in the pathogenesis of endometriosis.  In addition, we collaborate with many investigators at The Feinstein on other MIF-related projects (Drs. E. Miller, K. Ojamma, and Y. Al-Abed).
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Ovarian Cancer Discovery Program

We are currently developing a collaborative discovery program to identify potential risk factors and early diagnostic markers for ovarian cancer.  In conjunction with the Tissue Donation Program, we are collaborating with Drs. Barbara Sherry, PhD, Peter Gregersen, MD, John Lovecchio, MD, and the members of the Department of Gynecology Oncology to collect important biological samples for this program.
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