Interleukin-26 (IL-26) is an atypical proinflammatory
cytokine due to its binding to circulating
double-stranded DNA and direct antibacterial activity. Although IL-26 has been confirmed to be involved in the pathophysiology of
cancer, chronic inflammatory diseases and
infections, the diagnostic and prognostic values of IL-26 levels in
syphilis patients are not clear. This study aimed to investigate IL-26 levels in different stages of
syphilis progression.
Methods: A total of 30 healthy controls and 166 patients with
syphilis at different stages of
disease progression were enrolled. Serum IL-26 levels were quantified in accordance with the protocols of RayBio® Human Interleukin-26
Enzyme Linked
Immunosorbent Assay (ELISA) kits. Clinical laboratory diagnostic parameters and blood analysis data were detected and collected according to clinical medical laboratory standards.
Results: The levels of serum IL-26 were significantly higher in
neurosyphilis patients than in healthy subjects (6.87 (4.36, 12.14) and 1.67 (0.09, 4.89) pg/μL, respectively; ****p < 0.0001),
latent syphilis (1.48 (0.40, 2.05) pg/μL, ****p < 0.0001), seroresistant
syphilis (0.81 (0.20, 2.91) pg/μL, ****p < 0.0001) and
secondary syphilis (1.66 (0.41, 4.25) pg/μL, ****p < 0.0001) with data presented as the median with interquartile range. The concentration of serum IL-26 was most sensitive to serum
low-density lipoprotein concentration (r = -0.438, **p = 0.004) in
latent syphilis, urine epithelial cells (r = 0.459, **p = 0.003) in seroresistant
syphilis, and serum
creatinine levels (r = 0.463, **p = 0.004) and
urea creatinine ratio levels (r = 0.500, **p = 0.008) in
secondary syphilis patients. There was no significant correlation with the concentration of IL-26 and
toluidine red unheated serum test (TRUST) titers in each type of
syphilis patient.
Conclusion: