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Brain Behav Immun. 2018 Jan;67:47-53. doi: 10.1016/j.bbi.2017.08.010. Epub 2017 Aug 12.

Autonomic regulation of systemic inflammation in humans: A multi-center, blinded observational cohort study.

Author information

William Harvey Research Institute, Queen Mary University of London, UK; Centre for Cardiovascular and Metabolic Neuroscience, Department of Neuroscience, Physiology and Pharmacology, University College London, UK. Electronic address:
Department of Anaesthesia, Derriford Hospital, Plymouth Hospitals NHS Trust, Peninsula Schools of Medicine and Dentistry, Plymouth University, Plymouth, UK.
Department of Anaesthesia, Royal Bournemouth Hospital, Bournemouth, UK.
Clinical Physiology, Department of Medicine, University College London, London, UK.
Department of Anaesthesia, University College London Hospitals NHS Trust, London, UK.
Royal Preston Hospital, Lancashire Teaching Hospitals NHS Foundation Trust, Preston, UK.
Royal Surrey County Hospital, Guildford, UK.
William Harvey Research Institute, Queen Mary University of London, UK.



Experimental animal models demonstrate that autonomic activity regulates systemic inflammation. By contrast, human studies are limited in number and exclusively use heart rate variability (HRV) as an index of cardiac autonomic regulation. HRV measures are primarily dependent on, and need to be corrected for, heart rate. Thus, independent autonomic measures are required to confirm HRV-based findings. Here, the authors sought to replicate the findings of preceding HRV-based studies by using HRV-independent, exercise-evoked sympathetic and parasympathetic measures of cardiac autonomic regulation to examine the relationship between autonomic function and systemic inflammation.


Sympathetic function was assessed by measuring heart rate changes during unloaded pedaling prior to onset of exercise, divided into quartiles; an anticipatory heart rate (AHRR) rise during this period is evoked by mental stress in many individuals. Parasympathetic function was assessed by heart rate recovery (HRR) 60s after finishing cardiopulmonary exercise testing, divided into quartiles. Parasympathetic dysfunction was defined by delayed heart rate recovery (HRR) ≤, a threshold value associated with higher cardiovascular morbidity/mortality in the general population. Systemic inflammation was primarily assessed by neutrophil-lymphocyte ratio (NLR), where a ratio >4 is prognostic across several inflammatory diseases and correlates strongly with elevated plasma levels of pro-inflammatory cytokines. High-sensitivity C-reactive protein (hsCRP) was also measured.


In 1624 subjects (65±14y; 67.9% male), lower HRR (impaired vagal activity) was associated with progressively higher NLR (p=0.004 for trend across quartiles). Delayed HRR, recorded in 646/1624 (39.6%) subjects, was associated with neutrophil-lymphocyte ratio >4 (relative risk: 1.43 (95%CI: 1.18-1.74); P=0.0003). Similar results were found for hsCRP (p=0.045). By contrast, AHRR was not associated with NLR (relative risk: 1.24 (95%CI: 0.94-1.65); P=0.14).


Delayed HRR, a robust measure of parasympathetic dysfunction, is independently associated with leukocyte ratios indicative of systemic inflammation. These results further support a role for parasympathetic modulation of systemic inflammation in humans.


Autonomic; Exercise; Inflammation; Parasympathetic; Sympathetic

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