Introduction: Cerebrospinal fluid (CSF) cytokines and chemokines have been reported by several studies as useful markers to discriminate bacterial and viral meningitis (BM and VM). This study aimed to investigate if serum cytokine and chemokine profiles could also differentiate BM from VM, thus circumventing the need for an invasive lumbar puncture.
Methods: Serum cytokines and chemokines were measured in 153 samples from patients with BM (n=58), VM (n=69), and controls (C, n=26) using multiplex assays. Cytokine and chemokine concentrations were compared among groups, correlation analyses were performed, and BM and VM cases classification based on cytokine and chemokine patterns was tested using a Machine Learning algorithm.
Results: IL-8, IL-1β, IL-6, IL-10, TNF-α, MCP-1, and ENA-78 showed a pronounced increase in the BM group compared to C (P<0.01). Comparison of cytokines and chemokines in BM vs. VM showed significantly higher levels of MCP-1, IL-8, IL-1β, IL-6 and IL-10 (P<0.01). Serum cytokine and chemokine concentrations were highly correlated in BM, being strongest for: MCP-1/IL-8, MCP-1/IL-1β, and IL-8/IL-1β (r=0.83; r=0.72; r=0.78, respectively). In VM, cytokine and chemokine correlations were weaker. The best predictors in the cytokine and chemokine pattern identified with a Random Forest algorithm for classifying BM vs VM were IL-8 and IL-10, and IL-6, but the specificity and sensitivity were low (85% and 69%, respectively).
Conclusion: Our results suggest significant changes in serum IL-6, IL-8, IL-10, and IL-1β in BM, but these mediators may have limited value in differentiating BM from VM.
