Transcript levels of major interleukins in relation to the clinicopathological profile of patients with tuberculous intervertebral discs and healthy controls

Abstract

Objectives: The purpose of the present study was to simultaneously examine the transcript levels of a large number of interleukins (ILs; IL-9, IL-10, IL-12, IL-13, IL-16, IL-17, IL-18, IL-26, and IL-27) and investigate their correlation with the clinicopathological profiles of patients with tuberculous intervertebral discs.

Methods: Clinical data were collected from 150 patients participating in the study from January 2013 to December 2013. mRNA expression levels in 70 tuberculous, 70 herniated, and 10 control intervertebral disc specimens were determined by real-time polymerase chain reaction.

Results: IL-10, IL-16, IL-17, IL-18, and IL-27 displayed stronger expression in tuberculous spinal disc tissue than in normal intervertebral disc tissue (P<0.05). Our results illustrated multiple correlations among IL-10, IL-16, IL-17, IL-18, and IL-27 mRNA expression in tuberculous samples. Smoking habits were found to have a positive correlation with IL-17 transcript levels and a negative correlation with IL-10 transcript levels (P<0.05). Pain intensity, symptom duration, C-reactive protein levels, and the erythrocyte sedimentation rate exhibited multiple correlations with the transcript levels of several ILs (P<0.05).

Conclusions: The experimental data imply a double-sided effect on the activity of ILs in tuberculous spinal intervertebral discs, suggesting that they may be involved in intervertebral discs destruction. Our findings also suggest that smoking may affect the intervertebral discs destruction process of spinal tuberculosis. However, further studies are necessary to elucidate the exact role of ILs in the intervertebral discs destruction process of spinal tuberculosis.

Figure 1. Amplification curves.

A: IL-10, the Ct value was within the range of 24–27; B: IL-12, the Ct value was within the range of 26–28; C: IL-16, the Ct value was within the range of 26–28; D: IL-18, the Ct value was within the range of 20–22; E: IL-17, the Ct value was within the range of 20–22; and F: IL-27, the Ct value was within the range of 21–23.

Figure 2. Melting curves.

A: IL-10, the specific melting temperature was 79.96°C; B: IL-12, the specific melting temperature was 84.17°C; C: IL-16, the specific melting temper-ature was 73.73°C; D: IL-17, the specific melting temperature was 79.96°C; E: IL-18, the specific melting temperature was 84.87°C; and F: IL-27, the specific melting temperature was 80.03°C.

Figure 3. Standard curves.

A: IL-10, the efficiency was 95.242% and the correlation coefficient was 0.998; B: IL-12, the efficiency was 96.446% and the correlation coefficient was 0.991; C: IL-16, the efficiency was 98.241% and the correlation coefficient was 0.989; D: IL-17, the efficiency was 95.712% and the correlation coefficient was 0.999; E: IL-18, the efficiency was 97.501% and the correlation coefficient was 0.989; and F: IL-27, the efficiency was 97.081% and the correlation coefficient was 0.995.

Figure 4. Normalized transcript levels of interleukins (ILs) in the TB group with respect to pain intensity (A), symptom duration (B), C-reactive protein (CRP) levels (C) and the erythrocyte sedimentation rate (ESR) (D).

A illustrates that patients experiencing intense pain (visual analog scale [VAS] score = 8–10) exhibited higher IL-16, IL-17, and IL-18 mRNA levels than patients experiencing mild pain (VAS score = 0–4). Meanwhile, patients experiencing mild pain exhibited higher IL-10 and IL-27 mRNA levels than patients experiencing intense pain (P<0.05). B reveals that patients who experienced pain for 3–12 months exhibited significantly higher IL-16, IL-17, and IL-18 mRNA levels than those who experienced pain for <3 months. Conversely, patients who experienced pain for <3 months exhibited significantly higher IL-10 and IL-27 mRNA levels than those who experienced pain for 3–12 months (P<0.05). C indicates that the mRNA levels of IL-16 and IL-17 were significantly higher in patients with high CRP levels (>30 mg/L), whereas IL-10 and IL-27 levels were significantly higher in patients with low CRP levels (<10 mg/L) (P<0.005). D illustrates that the mRNA levels of IL-16 and IL-17 were significantly higher in patients with high ESRs (>40 mm/h). Conversely, IL-10 and IL-27 levels were significantly higher in patients with low ESRs (<20 mm/h) (P<0.005).