The Short-Term Kinetics of sICAM-1 after Induction of Acute Experimental Pain in Healthy Volunteers.

Philipp Lüke,Eduard Kraft,Shahnaz Christina Azad

doi:10.3390/jcm10092021

Philipp Lüke, Eduard Kraft + Show 1 more

Open Access

https://doi.org/10.3390/jcm10092021

Copy DOI

Abstract

Intercellular adhesion molecule-1 (ICAM-1) mediates extravasation of leukocytes, releasing proinflammatory cytokines or endogenous opioids in the inflamed tissue. Thus, ICAM-1 is a crucial component of peripheral antinociception. Previously, we demonstrated a significant correlation between the soluble form of ICAM (sICAM-1) in serum and pain intensity reported by chronic pain patients. The present study examines the role and kinetics of sICAM-1 in experimentally induced acute pain. Three groups of 10 subjects were exposed to 10 min of high (capsaicin-enhanced) or low-intensity heat pain or cold pain, respectively. Thermal stimuli were induced using a device for quantitative sensory testing. Topical capsaicin significantly increased heat pain intensity without the risk of thermal tissue damage. Pain intensity was recorded every minute during testing. sICAM-1 concentrations in serum were determined by ELISA before, immediately after, and 60 min after test termination. Among all experimental groups, sICAM-1 significantly decreased immediately after pain induction. After 60 min, sICAM-1 concentrations returned towards initial values. Interestingly, a linear correlation was found between the extent of sICAM-1 changes and the initial concentrations. Whereas high initial values led to a distinct decrease of sICAM-1, low concentrations tended to increase. There was no statistically significant correlation between levels or alterations of serum sICAM-1 and pain intensity reported by the test subjects. In contrast to our previous findings in chronic pain patients, the present results show that sICAM-1 values do not correlate with the intensity of acute experimental pain. However, we were able to detect short-term changes of sICAM-1 after induction of nociceptive thermal stimuli, suggesting that this marker is part of a demand-oriented homeostatically controlled system.

Highlights

Pain is an experience comprising sensorimotor, mental and affective components
We found a significant correlation between both the initial values of sICAM-1 serum concentration and pain level as well as their respective changes [11]
The experimental design described above allowed the induction of a significant heat and cold pain stimulus with an average perceived pain intensity of numerical pain rating scale (NRS) ≥ 6

Summary

Introduction

Despite the complexity of pain, the rated pain intensity is always assessed in daily clinical routine in order to adjust treatment. Used survey methods are scales developed to verbally, visually, or numerically record the intensity of perceived pain [1,2] Though, this type of survey is not always reliable. Other methods are required to quantify pain for patients who are unable to communicate due to their age, their underlying disease, or anesthesia. Surrogate markers such as elevated blood pressure, increased heart rate, or groaning are unspecific and often result in inadequate pain therapy [3,4]

Methods

Results

Conclusion