Strategies for serum chemokine/cytokine assessment as biomarkers of therapeutic response in HCV patients as a prototype to monitor immunotherapy of infectious diseases.

In this study, strategies for serum biomarker assessment were developed for therapeutic monitoring of HCV patients. For this purpose, serum chemokine/cytokine levels were measured by cytometric-bead-array in HCV patients, categorized according to immunotherapy response as: non-responder/NR, relapser/REL and sustained-virologic-responder/SVR. The results demonstrated an overall increase of serum chemokine/cytokine levels in HCV patients. In general, therapeutic failure was associated with presence of a predominant baseline proinflammatory pattern with enhanced CCL5/RANTES, IFN-α, IFN-γ along with decreased IL-10 levels in NR and increased IL-6 and TNF in REL. SVR displayed lower baseline proinflammatory status with decreased CXCL8/IL-8, IL-12 and IL-17 levels. The inability to uphold IFN-α levels during immunotherapy was characteristic of NR. Serum chemokine/cytokine signatures further support the deleterious effect of proinflammatory baseline status and the critical role of increased/persistent IFN-α levels to guarantee the sustained virologic response. The prominent baseline proinflammatory milieu observed in NR and REL yielded a restricted biomarker network with small number of neighborhood connections, whereas SVR displayed a network with integrated cytokine connectivity. Noteworthy was that SVR presented a shift towards a proinflammatory pattern upon immunotherapy, assuming a pattern similar to that observed in NR and REL at baseline. Moreover, the immunotherapy guided REL towards a profile similar to SVR at baseline. Analysis of baseline-fold changes during treatment pointed out IFN-α and TNF as high-performance biomarkers to monitor immunotherapy outcome. This knowledge may contribute for novel insights into the treatment and control of the continuous public health threat posed by HCV infection worldwide.