Differential expression of interferon inducible protein: Guanylate binding protein (GBP1 & GBP2) in severe dengue.

Dengue virus is reported to activate endothelial cells (EC), but the precise cause for severe dengue (SD) is not known. Guanylate binding proteins (GBPs) are IFN-inducible proteins secreted by ECs and are involved in the anti-oxidant and anti-viral response. The involvement of GBPs in the pathogenesis of dengue remains under explored. In the present study, we quantified the mRNA and protein levels of GBP1 and 2 during acute, defervescence and convalescent phase in SD-10, dengue without warning sign-15 and dengue with warning sign-25 compared to other febrile illnesses-10 and healthy controls-8 using RT-PCR and ELISA respectively. Lipid peroxidation in plasma samples were measured using the Kei Satoh method. Protein and DNA oxidation were determined by ELISA. The efficacy of the proteins in predicting disease severity was done by Support Vector Machine (SVM) model. A significant (P ≤ 0.01) decrease in the levels of mRNA and protein of both GBP1 and GBP2 was observed during defervescence in both SD and DWW cases. The levels were significantly (P ≤ 0.05) tapered off in SD cases from acute till critical phases compared to other study groups. DNA, protein and lipid oxidation markers showed an increasing trend in SD (P ≤ 0.01). Both GBP1 & 2 were found to be negatively associated plasma leakage and oxidative stress markers. EC's activated with SD serum showed a reduced expression of GBP 1 and 2. Nevertheless, the SVM model revealed that plasma levels of proteins along with clinical symptoms could predict the disease outcomes with higher precision. This is the first study reporting a downregulated expression of GBP1 & 2 and their association with oxidative stress and plasma leakage in dengue cases. This suggests the importance of GBPs in regulating disease manifestation. However, further investigations are required to ascertain its role as a biomarker or therapeutic target in dengue infection.

Expression dynamics of vascular endothelial markers: endoglin and syndecan-1 in predicting dengue disease outcome.

Plasma leakage is a hallmark process in dengue viral (DENV) infection that occurs due to the loss of vascular integrity in endothelial cells. Endoglin (ENG) and Syndecan-1 (SDC-1) are released by activated endothelial cells; however, the complete dynamics of its expression at the gene and protein levels during the course of DENV infection remains unknown. In the present study, we quantified the mRNA and soluble protein levels of ENG and SDC-1 in dengue cases during febrile, defervescence, and convalescence stages in Dengue without Warning Sign (DWOW-15), Dengue with Warning Sign (DWW-22), and Severe Dengue cases (SD-10) compared to nondengue Other Febrile Illness (OFI-10) and healthy control (HC-8). Respective protein and mRNA levels along with clinical characters were further analyzed for their efficacy in predicting disease outcomes using Support Vector Machine (SVM). We observed a steady and significant (P ≤ 0.01) increase in the levels of protein and mRNA of both the ENG and SDC-1 towards defervescence which is considered a critical phase in both severe and non-severe dengue cases. Importantly during the critical phase, the levels were significantly higher (P ≤ 0.001) in SD cases compared to DWW, DWOW, and OFI controls. However, at the time of admission (febrile), no such significant changes were observed within dengue, OFI, and healthy controls. SVM analysis revealed that the serum levels of ENG and SDC-1 along with other clinical symptoms could predict the disease severity with 100% accuracy. Based on the results we have proposed a mechanism on how ENG and SDC-1 could be involved in vascular dysfunction rather than just being a biomarker.