Background: Syphilis, while curable, may present with clinical findings or asymptomatically based on abnormal serological tests (latent stage). Distinguishing between active versus adequately treated infection can be difficult in the latent stage. New tests formulated on the basis of a host cellular response may allow for the differentiation of active or treated infection. While prior studies have linked certain cytokines with active infection using transcriptional profiles or single cytokine assays, recent advances enable the simultaneous measurement of multiple cytokines, i.e. 63 or more, from clinical specimens.
Methods: Using a 63-plex multiple cytokine assay from Luminex¨ (eBiosciences/Affymetrix, San Diego, California, USA), we conducted a pilot study comparing the median fluorescence intensity (MFI), a measure of signal in flow cytometry, in specimens from five patients with recent syphilis (RPR titer >1:32, TPPA+) and specimens from five syphilis-negative participants (TPPA-). Cytokine presence was compared using a Wilcoxon rank-sum test and p-values of <.05 were considered statistically significant.
Results: We identified significant differences in 16 cytokines profiles between samples from participants with and without syphilis. Of those cytokines, 8 were not previously described in the literature: interleukin 7, interferon gamma-induced protein 10, leptin, monocyte-specific chemokine 3, nerve growth factor, eotaxin, granulocyte macrophage colony-stimulating factor, and platelet-derived growth factor (Figure 1).
Conclusion: Our pilot study found at least 8 previously unidentified candidate cytokines associated with active-syphilis infection. Longitudinal studies and studies with larger sample sizes are needed to conduct cytokine cluster analyses.
Funding: This study is funded by the US National Institutes of Health (NIH) though the NIH/National Institute of Allergy and Infectious Diseases R-01 study, 1R01AI099727-01.
H. Maecker, None
Y. Rosenberg-Hasson, None
S. Leon, None
S. Vargas Rivera, None
K. Konda, None
J. Klausner, None