Altered Platelet Fatty Acids in Dengue Cases by Gas Chromatography-Mass Spectrometry Analysis.

BACKGROUND: The role of dengue virus in altering the functional properties of platelets remains poorly understood. Few studies have observed that changes in fatty acids are found to have an effect on platelet activation and aggregation. Also, platelet fatty acids have not been extensively studied in dengue so far. So, we aimed to study the fatty acids of platelet membranes in patients with dengue. METHODS: Gas chromatography-mass spectrometry (GC-MS) method was used to analyze fatty acids in the lipid extracts of platelets isolated from the study participants. RESULTS: GC-MS analysis of platelet lipids identified and quantified nearly 23 unique lipid molecules on platelet membrane. We observed significant alterations with some of the fatty acids in patients with dengue compared to controls. Within dengue cases, increase in unsaturated fatty acids in severe dengue was observed compared to non-severe dengue. From baseline to defervescence, no difference in fatty acids was observed in dengue platelets. This indicates that in dengue, platelet physiology remains altered even after the febrile phase. CONCLUSION: To the best of our knowledge, this is the first study characterizing the differential expression of platelet fatty acids in dengue infection. However, further studies are warranted to expound the underlying cause for thrombocytopenia and platelet dysfunction in dengue.

Dynamic modulation of DC-SIGN and FcΥR2A receptors expression on platelets in dengue.

Platelet activation has been reported to play a major role in inflammatory response and thrombocytopenia during dengue viral infection. Cells expressing FcϒR2Aand DC-SIGN receptors are reported to be involved in dengue virulence. The present study is designed to assess the expression level of these two receptors on platelet surface collected from dengue patients and to study its association in patients with platelet RNA positive for dengue virus. This was an analytical cross-sectional study carried out in JIPMER hospital, Puducherry. Forty-four patients with dengue infection as cases and 44 patients with non dengue acute other febrile illness(OFI) as controls were recruited. Peripheral venous blood was withdrawn on day of admission, day 3 post admission and day of discharge and serological tests for NS1 dengue antigen and anti IgM antibody were analyzed for diagnosis of dengue infection. Platelet rich plasma was assessed for DC SIGN, FcϒR2A levels and platelets separated from dengue patients were subjected to RNA extraction and detection of presence of viral RNA. The study observed a decreased expression of DC-SIGN and FcϒR2A on platelets in dengue patients compared to OFI group on all the time points. Further, cells expressing DC-SIGN and FcϒR2A were found to be decreased on platelets in dengue patients who were positive for NS1 antigen. DC-SIGN and FcϒR2A expression was also found to be notably decreased in patients positive for platelet DENV RNA when compared with patients negative for platelet DENV RNA. Our results suggest that DC-SIGN and FcϒR2A, which are receptors for viral capture and immune mediated clearance respectively, might be down regulated on platelets in patients with dengue infection. The decreased receptor expression diminishes platelet activation and subsequently has protective action on the host from the ongoing conflict between immune system and dengue virus.

Lipid peroxidation, DNA damage, and apoptosis in dengue fever.

Interplay between the apoptosis, DNA damage, and oxidative stress as a host response to dengue viral infections remains unclear. Peripheral blood mononuclear cells (PBMCs) were isolated from 60 dengue infected patients, 20 patients with febrile illness other than dengue (OFI) and 10 non-febrile illness (NFI) patients. DNA damage in the PBMCs was assessed using single cell gel electrophoresis and stages of apoptosis underwent by the PBMCs were studied by Annexin-PI staining using flow cytometry. Plasma levels of malondialdehyde levels were estimated using thiobarbituric acid assay. Dengue infected individuals had showed increased DNA damage than NFI and OFI controls at the time of admission. Annexin-PI staining revealed increased frequency of apoptotic cells in dengue infected PBMCs than controls during the admission time. Similar pattern was observed in samples collected around defervescence. Within the dengue cases, percentage of live cells was higher in non-severe dengue than severe dengue at both the time points. Follow-up samples in dengue showed less number of live cells and higher percentage of apoptotic cells with respect to their baseline and this was reversed in case of OFI. Plasma malondialdehyde levels were found to be relatively higher in dengue cases than controls at admission and around defervescence. Significant positive correlation between DNA damage, apoptosis, and plasma malondialdehyde levels might pave a way for understanding the complex interactions between virus and hosts response thereby aids in identifying plausible immunopathological links contributing to disease pathogenesis. © 2018 IUBMB Life, 70(11):1133-1143, 2018.