Increased serum levels of macrophage activation marker sCD163 in Dengue patients.

BACKGROUND: Dengue viruses are known to infect and replicate in macrophages. Thus studying the host responsive molecules that are specifically released by macrophages during the course of dengue infection may provide better understanding on dengue immunopathogenesis. Soluble CD163 (sCD163) is a scavenger receptor, highly expressed on macrophages reported to be involved in some viral disease. The participation of sCD163 in dengue is not known. OBJECTIVE: The present study aimed to explore the role of sCD163 as a potential biomarker for predicting dengue disease. STUDY DESIGN: Using a case-control design, 82 dengue subjects consisting of 69 non-severe dengue (NSD) and 13 severe dengue (SD) along with 32 non-dengue other febrile illness (OFI) subjects and 30 healthy subjects were involved in the study. The serum concentration of sCD163 was determined in the study subjects at admission and around defervescence using ELISA. Statistical analysis was done using Mann-Whitney U test andWilcoxon signed rank test. RESULTS: The study recorded a significant increase in the sCD163 serum level at defervescence phase specifically among dengue group compared to OFI. sCD163 was also found to be significantly higher in secondary cases compared to primary at both admission and defervescence. Furthermore,a higher level of sCD163 was also observed in SD compared to NSD cases, although no statistical significance was observed CONCLUSION: The study substantiates the role of macrophage activation in dengue pathogenesis and further study is needed to decipher the exact role of sCD163 in the disease pathogenesis and to explore its potential as a marker for the early prediction of dengue severity.

Inhibition of Platelet Aggregation by the Leaf Extract of Carica papaya During Dengue Infection: An In Vitro Study.

Dengue cases were reported to undergo platelet activation and thrombocytopenia by a poorly understood mechanism. Recent studies suggested that Carica papaya leaf extract could recover the platelet count in dengue cases. However, no studies have attempted to unravel the mechanism of the plant extract in platelet recovery. Since there are no available drugs to treat dengue and considering the significance of C. papaya in dengue treatment, the current study aimed to evaluate two research questions: First one is to study if the C. papaya leaf extract exerts its action directly on platelets and second one is to understand if the extract can specifically inhibit the platelet aggregation during dengue viral infection. Sixty subjects with dengue positive and 60 healthy subjects were recruited in the study. Platelet-rich plasma (PRP) and platelet-poor plasma were prepared from both the dengue-infected and healthy control blood samples. Effect of the leaf extract obtained from C. papaya leaves was assessed on plasma obtained as well as platelets collected from both healthy and dengue-infected individuals. Platelet aggregation was significantly reduced when leaf extract preincubated with dengue plasma was added into control PRP, whereas no change in aggregation when leaf extract incubated-control plasma was added into control PRP. Upon direct addition of C. papaya leaf extract, both dengue PRP and control PRP showed a significant reduction in platelet aggregation. Within the dengue group, PRP from severe and nonsevere cases showed a significant decrease in aggregation without any difference between them. From the study, it is evident that C. papaya leaf extract can directly act on platelet. The present study, the first of its kind, found that the leaf extract possesses a dengue-specific neutralizing effect on dengue viral-infected plasma that may exert a protective role on platelets.