Pro- and anti-inflammatory cytokines (adipokines) associated with adipose tissue can modulate inflammatory processes and lead to systemic inflammatory conditions such as metabolic syndrome. In the present pilot study, we investigated 3 major adipokines (leptin, adiponectin, and resistin) and 2 nonspecific proinflammatory cytokines (tumor necrosis factor α and interleukin-6) with regard to their association with postoperative pain intensity.
We analyzed a total of 45 single-nucleotide polymorphisms of the adipokines in 57 patients with postlaparotomy pain. We adjusted for multiple testing to reduce the chance of false-positive results by controlling the false discovery rate. Serum levels of the adipokines and proinflammatory cytokines were measured in another 36 patients undergoing laparotomy. A stepwise multiple linear regression analysis using these measurements and opioid dosages as independent variables was performed to explore the factors associated with postoperative pain.
Only 1 variant of the resistin gene (rs3745367) demonstrated a significant association with postoperative pain (P < .002). Patients exhibiting homozygosity for the minor alleles (n = 7; numerical rating scale [NRS], 2.3 ± 1.3) demonstrated lower pain intensity compared with those exhibiting homozygosity for the major alleles (n = 29; NRS, 3.8 ± 1.0; P = .004) and heterozygosity for the minor alleles (n = 21; NRS, 4.2 ± 0.8; P < .001). Only serum resistin levels showed a positive association with postoperative pain.
A genetic variant of resistin and serum resistin levels were associated with postoperative pain intensity, while other adipokines and cytokines exhibit no such association. Resistin can alter the inflammatory responses in postoperative wounds, although it could be a determinant factor that is independent of inflammatory processes. Resistin may be a novel marker for postoperative pain intensity.
From the Departments of *Anesthesiology and Pain Relief Center
†Pain and Palliative Medicine, The University of Tokyo Hospital, Tokyo, Japan
‡Addictive Substance Project, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
§Department of Surgery, Toho University Medical Center, Sakura Hospital, Chiba, Japan.
Published ahead of print 16 February 2018.
Accepted for publication February 16, 2018.
Funding: This study was funded by a Ministry of Health, Labour, and Welfare Science Research Grant (H21-Cancer-011 and H26-Cancer-060).
The authors declare no conflicts of interest.
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Address correspondence to Masahiko Sumitani, MD, PhD, Department of Pain and Palliative Medicine, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo, Tokyo 113-8655, Japan. Address e-mail to SUMITANIM-ANE@h.u-tokyo.ac.jp.