Cytokine expression profile of dengue patients at different phases of illness

Abstract

Background: Dengue is an important medical problem, with symptoms ranging from mild dengue fever to severe forms of the disease, where vascular leakage leads to hypovolemic shock. Cytokines have been implicated to play a role in the progression of severe dengue disease; however, their profile in dengue patients and the synergy that leads to continued plasma leakage is not clearly understood. Herein, we investigated the cytokine kinetics and profiles of dengue patients at different phases of illness to further understand the role of cytokines in dengue disease.

Methods and findings: Circulating levels of 29 different types of cytokines were assessed by bead-based ELISA method in dengue patients at the 3 different phases of illness. The association between significant changes in the levels of cytokines and clinical parameters were analyzed. At the febrile phase, IP-10 was significant in dengue patients with and without warning signs. However, MIP-1β was found to be significant in only patients with warning signs at this phase. IP-10 was also significant in both with and without warning signs patients during defervescence. At this phase, MIP-1β and G-CSF were significant in patients without warning signs, whereas MCP-1 was noted to be elevated significantly in patients with warning signs. Significant correlations between the levels of VEGF, RANTES, IL-7, IL-12, PDGF and IL-5 with platelets; VEGF with lymphocytes and neutrophils; G-CSF and IP-10 with atypical lymphocytes and various other cytokines with the liver enzymes were observed in this study.

Conclusions: The cytokine profile patterns discovered between the different phases of illness indicate an essential role in dengue pathogenesis and with further studies may serve as predictive markers for progression to dengue with warning signs.

Figure 1. Cytokine trends over the three different phases of illness.

The mean levels of (A) inflammatory cytokines, (B) chemokines and (C) adhesion molecules and growth factors in dengue patients without warning signs (DwoWS) (red symbol), dengue patients with warning signs (DwWS) (blue symbol) and healthy controls (black line) at different phase of illness (Feb = Febrile; Def = Defervescence; Conv = Convalescence). Error bars indicate standard error mean (SEM).

Figure 2. Distribution of raw cytokine response values in dengue without warning signs (DwoWS) and dengue with warning signs (DwWS) compared with healthy controls.

Levels of (A) IP-10, (B) MIP-1β, (C) MCP-1 and (D) G-CSF in DwoWS (red symbol), DwWS (blue symbol) patients at different phase of illness compared with control subjects (black symbol). The SEM are indicated by the error bars in the scatter plot. Statistical significance based on the Kruskal-Wallis, Dunn’s multiple comparison test where *-P<0.05; **-P<0.01, and ***-P<0.001.

Figure 3. Comparison of mean cytokine levels in primary and secondary dengue infections.

Primary and secondary infection status was determined by haemagglutination inhibition assay. Mean with SEM of seven cytokines (three at febrile phase of illness and 4 at defervescence). Statistical significance based on the Mann-Whitney U test where *-P<0.05 and **-P<0.01.