Inducible nitric oxide synthase (iNOS) expression in monocytes during acute Dengue Fever in patients and during in vitro infection

Abstract

Mononuclear phagocytes are considered to be main targets for Dengue Virus (DENV) replication. These cells are activated after infection, producing proinflammatory mediators, including tumournecrosis factor-α, which has also been detected in vivo. Nitric oxide (NO), usually produced by activated mononuclear phagocytes, has antimicrobial and antiviral activities. MethodsThe expression of DENV antigens and inducible nitric oxide synthase (iNOS) in human blood isolated monocytes were analysed by flow cytometry using cells either from patients with acute Dengue Fever or after DENV-1 in vitro infection. DENV-1 susceptibility to iNOS inhibition and NO production was investigated using N G -methyl L-Arginine (N G MLA) as an iNOS inhibitor, which was added to DENV-1 infected human monocytes, and sodium nitroprussiate (SNP), a NO donor, added to infected C6/36 mosquito cell clone. Viral antigens after treatments were detected by flow cytometry analysis. ResultsINOS expression in activated monocytes was observed in 10 out of 21 patients with Dengue Fever and was absent in cells from ten healthy individuals. DENV antigens detected in 25 out of 35 patients, were observed early during in vitro infection (3 days), significantly diminished with time, indicating that virus replicated, however monocytes controlled the infection. On the other hand, the iNOS expression was detected at increasing frequency in in vitro infected monocytes from three to six days, exhibiting an inverse relationship to DENV antigen expression. We demonstrated that the detection of the DENV-1 antigen was enhanced during monocyte treatment with N G MLA. In ConclusionThis study is the first to reveal the activation of DENV infected monocytes based on induction of iNOS both in vivo and in vitro, as well as the susceptibility of DENV-1 to a NO production.

Activated peripheral lymphocytes with increased expression of cell adhesion molecules and cytotoxic markers are associated with dengue fever disease

“…Isolates were demonstrated by immunofluorescence assay. Alternatively, virus was antigenically detected in monocytes by flow cytometry (Neves-Souza et al 2005) in 23 out of 35 patients from 1-10 days after disease outset but not after 11 days. Dengue immune response was considered as primary or secondary by IgG ELISA according to previously established criteria.…”

Recent Advances in Deciphering Viral and Host Determinants of Dengue Virus Replication and Pathogenesis

“…In particular, whether hepatocytes, lymphocytes, endothelial cells, and neuronal cells are target cells for DENV replication in vivo has not been conclusively demonstrated. Apart from autopsy studies, further evidence for cellular tropism in vivo has included the detection of DENV in Langerhans cells (skin-resident DCs) after inoculation with an experimental vaccine (197) and in monocytes and, in some instances, B cells in peripheral blood from naturally infected patients (101,141,168; A. Durbin, A. Balmaseda, and E. Harris, unpublished data).The first points in the viral life cycle that determine cellular tropism are the stages of adsorption and entry. It is generally accepted that DENV gains entry to its target cell by receptormediated endocytosis (RME).…”

The IMMUNOSTIMULAN POTENTIAL OF TENGGULUN (PROTIUM JAVANICUM) LEAVES TOWARDS T CELL CD4+ AND IFNγ SECRETION ON PBMC CHICKEN

“…3,16 The treatment of K + (inoculated ND and extract meniran) with P1 (inoculated with ND virus and Tenggulun leaf extracts of 5μg) are not significantly different in secreting IFNγ, because the competition between the plant extracts with the viral antigen induces similar APC cells (dendritic cells); thus, the extract's effect of 5μg dose is not enough to modulate the secretion of IFNγ post virus infection. 12,17 conclusion Based on this study we can conclude that the leaf extract of 10μg Tenggulun has higher immunomodulatory potential than the 5μg dose in increasing the expression and secretion of CD4 + IFNγ in PBMC cultures which are infected by ND virus. …”