Multiplex cytokine profile from dengue patients: MIP-1beta and IFN-gamma as predictive factors for severity

<p>Abstract</p> <p>Background</p> <p>Dengue virus pathogenesis is not yet fully understood and the identification of patients at high risk for developing severe disease forms is still a great challenge in dengue patient care. During the present study, we evaluated prospectively the potential of cytokines present in plasma from patients with dengue in stratifying disease severity.</p> <p>Methods</p> <p>Seventeen-cytokine multiplex fluorescent microbead immunoassay was used for the simultaneous detection in 59 dengue patients. GLM models using bimodal or Gaussian family were determined in order to associate cytokines with clinical manifestations and laboratory diagnosis.</p> <p>Results</p> <p>IL-1β, IFN-γ, IL-4, IL-6, IL-13, IL-7 and GM-CSF were significantly increased in patients with severe clinical manifestations (severe dengue) when compared to mild disease forms (mild dengue). In contrast, increased MIP-1β levels were observed in patients with mild dengue. MIP-1β was also associated with CD56+NK cell circulating rates. IL-1β, IL-8, TNF-α and MCP-1 were associated with marked thrombocytopenia. Increased MCP-1 and GM-CSF levels correlated with hypotension. Moreover, MIP-1β and IFN-γ were independently associated with both dengue severity and disease outcome.</p> <p>Conclusion</p> <p>Our data demonstrated that the use of a multiple cytokine assay platform was suitable for identifying distinct cytokine profiles associated with the dengue clinical manifestations and severity. MIP-β is indicated for the first time as a good prognostic marker in contrast to IFN-γ that was associated with disease severity.</p

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 tumour-necrosis factor-α, which has also been detected in vivo. Nitric oxide (NO), usually produced by activated mononuclear phagocytes, has antimicrobial and antiviral activities. METHODS: The 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. RESULTS: INOS 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 the mosquito cell line C6/36, virus detection was significantly reduced in the presence of SNP, when compared to that of untreated cells. CONCLUSION: This 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

Dengue-2 and yellow fever 17DD viruses infect human dendritic cells, resulting in an induction of activation markers, cytokines and chemokines and secretion of different TNF-α and IFN-α profiles

Flaviviruses cause severe acute febrile and haemorrhagic infections, including dengue and yellow fever and the pathogenesis of these infections is caused by an exacerbated immune response. Dendritic cells (DCs) are targets for dengue virus (DENV) and yellow fever virus (YF) replication and are the first cell population to interact with these viruses during a natural infection, which leads to an induction of protective immunity in humans. We studied the infectivity of DENV2 (strain 16681), a YF vaccine (YF17DD) and a chimeric YF17D/DENV2 vaccine in monocyte-derived DCs in vitro with regard to cell maturation, activation and cytokine production. Higher viral antigen positive cell frequencies were observed for DENV2 when compared with both vaccine viruses. Flavivirus-infected cultures exhibited dendritic cell activation and maturation molecules. CD38 expression on DCs was enhanced for both DENV2 and YF17DD, whereas OX40L expression was decreased as compared to mock-stimulated cells, suggesting that a T helper 1 profile is favoured. Tumor necrosis factor (TNF)-α production in cell cultures was significantly higher in DENV2-infected cultures than in cultures infected with YF17DD or YF17D/DENV. In contrast, the vaccines induced higher IFN-α levels than DENV2. The differential cytokine production indicates that DENV2 results in TNF induction, which discriminates it from vaccine viruses that preferentially stimulate interferon expression. These differential response profiles may influence the pathogenic infection outcome

Dengue-2 infection and the induction of apoptosis in human primary monocytes

Monocytes/macrophages are important targets for dengue virus (DENV) replication; they induce inflammatory mediators and are sources of viral dissemination in the initial phase of the disease. Apoptosis is an active process of cellular destruction genetically regulated, in which a complex enzymatic pathway is activated and may be trigged by many viral infections. Since the mechanisms of apoptotic induction in DENV-infected target cells are not yet defined, we investigated the virus-cell interaction using a model of primary human monocyte infection with DENV-2 with the aim of identifying apoptotic markers. Cultures analyzed by flow cytometry and confocal microscopy yielded DENV antigen positive cells with rates that peaked at the second day post infection (p.i.), decayed afterwards and produced the apoptosis-related cytokines TNF-α and IL-10. Phosphatidylserine, an early marker for apoptosis, was increased at the cell surface and the Fas death receptor was upregulated at the second day p.i. at significantly higher rates in DENV infected cell cultures than controls. However, no detectable changes were observed in the expression of the anti-apoptotic protein Bcl-2 in infected cultures. Our data support virus modulation of extrinsic apoptotic factors in the in vitro model of human monocyte DENV-2 infection. DENV may be interfering in activation and death mechanisms by inducing apoptosis in target cells

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

The immune mechanisms involved in dengue fever and dengue hemorrhagic/dengue shock syndrome are not well understood. The ex vivo activation status of immune cells during the dengue disease in patients was examined. CD4and CD8 T cells were reduced during the acute phase. Interestingly, CD8 T cells co-expressing activation marker HLA-DR, Q, P, and cytolytic granule protein-Tia-1 were significantly higher in dengue patients than in controls. Detection of adhesion molecules indicated that in dengue patients the majority of T cells (CD4 and CD8) express the activation/memory phenotype, characterized as CD44HIGH and lack the expression of the naïve cell marker, CD62L LOW. Also, the levels of T cells co-expressing ICAM-1 (CD54), VLA-4, and LFA-1 (CD11a) were significantly increased. CD8 T lymphocytes expressed predominantly low levels of anti-apoptotic molecule Bcl-2 in the acute phase, possibly leading to the exhibition of a phenotype of activated/effector cells. Circulating levels of IL-18, TGF-b1 and sICAM-1 were significantly elevated in dengue patients. Early activation events occur during acute dengue infection which might contribute to viral clearance. Differences in expression of adhesion molecules among CD4 and CD8 T cells might underlie the selective extravasation of these subsets from blood circulation into lymphoid organs and/or tissues. In addition, activated CD8 T cells would be more susceptible to apoptosis as shown by the alteration in Bcl-2 expression. Cytokines such as IL-18, TGF-b1, and sICAM-1 may be contributing by either stimulating or suppressing the adaptative immune response, during dengue infection, thereby perhaps establishing a relationship with disease severity

Dengue-2 infection and the induction of apoptosis in human primary monocytes

Monocytes/macrophages are important targets for dengue virus (DENV) replication; they induce inflammatory mediators and are sources of viral dissemination in the initial phase of the disease. Apoptosis is an active process of cellular destruction genetically regulated, in which a complex enzymatic pathway is activated and may be trigged by many viral infections. Since the mechanisms of apoptotic induction in DENV-infected target cells are not yet defined, we investigated the virus-cell interaction using a model of primary human monocyte infection with DENV-2 with the aim of identifying apoptotic markers. Cultures analyzed by flow cytometry and confocal microscopy yielded DENV antigen positive cells with rates that peaked at the second day post infection (p.i.), decayed afterwards and produced the apoptosis-related cytokines TNF-&#945; and IL-10. Phosphatidylserine, an early marker for apoptosis, was increased at the cell surface and the Fas death receptor was upregulated at the second day p.i. at significantly higher rates in DENV infected cell cultures than controls. However, no detectable changes were observed in the expression of the anti-apoptotic protein Bcl-2 in infected cultures. Our data support virus modulation of extrinsic apoptotic factors in the in vitro model of human monocyte DENV-2 infection. DENV may be interfering in activation and death mechanisms by inducing apoptosis in target cells