Increased Expression of Inflammatory Cytokines and Discogenic Neck Pain

Abstract

Objective: Although neck pain has become a serious economic and social problem worldwide, the etiology remains poorly understood. The aim of current study is to explore the possible pathogenesis of discogenic neck pain by analyzing the relationship between inflammatory cytokines and discogenic neck pain and provide a valuable reference for the prevention and treatment of discogenic neck pain.

Methods: A total of 111 cervical disc samples were collected between October 1, 2021, and October 1, 2022: 38 samples from the discogenic neck pain group, 41 samples from the symptomatic control group, and 32 samples from the normal control group. The concentration of nitric oxide (NO), interleukin (IL)-1, interleukin (IL)-6, and tumor necrosis factor alpha (TNF-α) was determined using the enzyme-linked immunosorbent assay in each sample, and the degeneration degree of the target discs were evaluated using T2-weighted sagittal magnetic resonance imaging (MRI) according to the Miyazaki disc degeneration grading system. Whether the differences among the three groups were statistically significant was tested using one-way analysis of variance and an unpaired t-test, respectively.

Results: The differences of the baseline characteristics were not statistically significant between the discogenic neck pain group and the symptomatic control group (p > 0.05). The expression of inflammatory cytokines in disc samples from the discogenic neck pain group (NO: 9.89 ± 1.75, IL-1β: 10.74 ± 1.92, IL-6:31.65 ± 2.46, and TNF-α: 5.96 ± 1.91) was increased in comparison with the disc samples from both the symptomatic control group (NO: 7.15 ± 2.78, IL-1β: 8.03 ± 1.87, IL-6: 25.79 ± 2.12, and TNF-α: 4.18 ± 2.87) and the normal control group (NO: 6.11 ± 1.37, IL-1β: 5.84 ± 2.25, IL-6: 20.65 ± 1.26, and TNF-α: 2.05 ± 0.58). The differences were statistically significant (p < 0.001). Further, there were no statistical differences in the degree of degeneration between discogenic neck pain group and symptomatic control group.

Conclusions: The increased expression of inflammatory cytokines in diseased cervical intervertebral discs might play a key role in the pathogenesis of discogenic neck pain. Although inflammation is involved in intervertebral disc degeneration, there is no linear positive correlation between the concentration of inflammatory cytokines and the degree of disc degeneration.

Keywords: cytokines; intervertebral disc degeneration; low back pain; neck pain; pathogenesis.

FIGURE 1

The box plot shows the distribution characteristics of the data of NO and TNF‐α in the discogenic neck pain group, the symptomatic control group, and the normal control group. The small square inside the box indicates the mean value. The red line inside the box indicates the median. The colored spot outside the box shows the outliers. Unit of NO: μmol/g protein. Unit of TNF‐α: pg./g. NO, nitric oxide; TNF‐α, tumor necrosis factor alpha.

FIGURE 2

The box plot shows the distribution characteristics of the data of IL‐1β and IL‐6 in the discogenic neck pain group, the symptomatic control group, and the normal control group. The small square inside the box shows the mean value. The red line inside the box shows the median. The black spot outside the box shows the outliers. Unit of IL‐1β and IL‐6: pg./g. IL, interleukin.