Activation of the "Splenocardiac Axis" by electronic and tobacco cigarettes in otherwise healthy young adults. Issue 17 (12th September 2017) - Boas, Zachary
Abstract: The "Splenocardiac Axis" describes an inflammatory signaling network underlying acute cardiac ischemia, characterized by sympathetic nerve stimulation of hematopoietic tissues, such as the bone marrow and spleen, which then release proinflammatory monocytes that populate atherosclerotic plaques, thereby promoting ischemic heart disease. Electronic (e) cigarettes, like tobacco cigarettes trigger sympathetic nerve activation, but virtually nothing is known about their influence on hematopoietic and vascular tissues and cardiovascular risks. The objective of this study was to determine if the Splenocardiac Axis is activated in young adults who habitually use either tobacco or e‐cigarettes. In otherwise healthy humans who habitually use tobacco cigarettes or e‐cigarettes (not both), we used 18 F‐flurorodeoxyglucose positron emission tomography/computer tomography (FDG‐PET/CT) to test the hypothesis that tobacco or e‐cigarettes increased metabolic activity of the hematopoietic and vascular tissues. FDG uptake in the spleen increased from nonuser controls (1.62 ± 0.07), to the e‐cigarette users (1.73 ± 0.04), and was highest in tobacco cigarette smokers (1.82 ± 0.09; monotone P = 0.05). Similarly, FDG uptake in the aorta increased from the nonuser controls (1.87 ± 0.07) to the e‐cigarette users (1.98 ± 0.07), and was highest in tobacco cigarette smokers (2.10 ± 0.07; monotone P = 0.04). FDG uptake in the skeletal muscle, which served as a control tissue, was not different between the groups. In conclusion, these findings are consistent with activation of the Splenocardiac Axis by emissions from tobacco cigarettes and e‐cigarettes. This activation suggests a mechanism by which tobacco cigarettes, and potentially e‐cigarettes, may lead to increased risk of future cardiovascular events. Abstract : In tobacco‐ or electronic‐cigarette smokers, FDG‐PET/CT was used to measure metabolic activity in hematopoietic and vascular tissues. FDG uptake in the spleen and aorta increased from controls, to electronic‐cigarette users, to tobacco‐cigarette smokers, possibly indicative of graded activation of the Splenocardiac Axis, an inflammatory signaling network underlying cardiac ischemia.