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Abstract Background Dengue, one of the most important arboviral diseases of humans, may cause severe systemic disease. Although dengue virus (DENV) has been considered to be a non-neurotropic virus, dengue infection has been associated recently with a series of neurological syndromes, including encephalitis. In this work, we evaluated behavioral changes and inflammatory parameters in C57BL/6 mice infected with non-adapted dengue virus 3 (DENV-3) genotype I. Methods C57BL/6 mice received 4 × 103 PFU of DENV-3 by an intracranial route. We evaluated the trafficking of leukocytes in brain microvasculature using intravital microscopy, and evaluated chemokine and cytokine profiling by an ELISA test at 3 and 6 days post infection (p.i.). Furthermore, we determined myeloperoxidase activity and immune cell populations, and also performed histopathological analysis and immunostaining for the virus in brain tissue. Results All animals developed signs of encephalitis and died by day 8 p.i. Motor behavior and muscle tone and strength parameters declined at day 7 p.i. We observed increased leukocyte rolling and adhesion in brain microvasculature of infected mice at days 3 and 6 p.i. The infection was followed by significant increases in IFN-γ, TNF-α, CCL2, CCL5, CXCL1, and CXCL2. Histological analysis showed evidence of meningoencephalitis and reactive gliosis. Increased numbers of neutrophils, CD4+ and CD8+ T cells were detected in brain of infected animals, notably at day 6 p.i. Cells immunoreactive for anti-NS-3 were visualized throughout the brain. Conclusion Intracerebral infection with non-adapted DENV-3 induces encephalitis and behavioral changes that precede lethality in mice.

Background Cerebral malaria (CM) is a clinical syndrome resulting from Plasmodium falciparum infection. A wide range of clinical manifestations follow the disease including cognitive dysfunction, seizures and coma. CM pathogenesis remains incompletely understood and without treatment this condition is invariably fatal. Artesunate has been accepted as the most effective drug for treating severe malaria. Besides its antiparasitic activity, an antiinflammatory property has also been reported. In the current study, the immunomodulatory role of artesunate was investigated using a Plasmodium berghei ANKA model of CM, trough evaluation of behavioural changes and cytokines expression in hippocampus and in frontal cortex. Methods C57Bl/6 mice were infected with P. berghei by intraperitoneal route, using a standardized inoculation of 106 parasitized erythrocytes. Memory function was evaluated using the stepdown inhibitory avoidance test. The mRNA expression of IFN-γ, IL-1β, IL-6 and TNF in the frontal cortex and hippocampus of control and infected mice on day 5 post-infection were estimated by quantitative real time PCR. Plasmodium berghei -infected mice also received intraperitoneally a single dose of artesunate (32 mg/kg) on day 4 post-infection, and 24 hours after treatment behavioural and immunological analysis were performed. The protein levels of cytokines IL-2, IL-6, IL-10, IL-17, IFN-γ, TNF in the serum, frontal cortex and hippocampus of controls and P. berghei -infected mice treated or not treated with artesunate were determined using a cytometric bead array (CBA) kit. The survival and neurological symptoms of CM were also registered. Results CM mice presented a significant impairment of aversive memory compared to controls on day 5 post-infection. A higher mRNA expression of pro-inflammatory cytokines was found in the hippocampus and frontal cortex of infected mice. A single dose of artesunate was also able to decrease the expression of inflammatory cytokines in the hippocampus and frontal cortex of P. berghei-infected mice. In parallel, a significant improvement in neurological symptoms and survival were observed in artesunate treated mice. Conclusions In summary, the current study provided further evidence that CM affects key brain areas related to cognition process. In addition, different patterns of cytokine expression during the course of CM could be modulated by a single administration of the anti-malarial artesunate. [ABSTRACT FROM AUTHOR]

Background: Dengue, one of the most important arboviral diseases of humans, may cause severe systemic disease. Although dengue virus (DENV) has been considered to be a non-neurotropic virus, dengue infection has been associated recently with a series of neurological syndromes, including encephalitis. In this work, we evaluated behavioral changes and inflammatory parameters in C57BL/6 mice infected with non-adapted dengue virus 3 (DENV-3) genotype I. Methods: C57BL/6 mice received 4 x 103 PFU of DENV-3 by an intracranial route. We evaluated the trafficking of leukocytes in brain microvasculature using intravital microscopy, and evaluated chemokine and cytokine profiling by an ELISA test at 3 and 6 days post infection (p.i.). Furthermore, we determined myeloperoxidase activity and immune cell populations, and also performed histopathological analysis and immunostaining for the virus in brain tissue. Results: All animals developed signs of encephalitis and died by day 8 p.i. Motor behavior and muscle tone and strength parameters declined at day 7 p.i. We observed increased leukocyte rolling and adhesion in brain microvasculature of infected mice at days 3 and 6 p.i. The infection was followed by significant increases in IFN- γ, TNF- α, CCL2, CCL5, CXCL1, and CXCL2. Histological analysis showed evidence of meningoencephalitis and reactive gliosis. Increased numbers of neutrophils, CD4+ and CD8+ T cells were detected in brain of infected animals, notably at day 6 p.i. Cells immunoreactive for anti-NS-3 were visualized throughout the brain. Conclusion: Intracerebral infection with non-adapted DENV-3 induces encephalitis and behavioral changes that precede lethality in mice. [ABSTRACT FROM AUTHOR]

We demonstrated recently that P8A-CCL2, a monomeric variant of the chemokine CCL2/MCP-1, is unable to induce cellular recruitment in vivo, despite full activity in vitro. Here, we show that this variant is able to inhibit CCL2 and thioglycollate-mediated recruitment of leukocytes into the peritoneal cavity and recruitment of cells into lungs of OVA-sensitized mice. This anti-inflammatory activity translated into a reduction of clinical score in the more complex inflammatory model of murine experimental autoimmune encephalomyelitis. Several hypotheses for the mechanism of action of P8A-CCL2 were tested. Plasma exposure following s.c. injection is similar for P8A-CCL2 and wild-type (WT) CCL2, ruling out the hypothesis that P8A-CCL2 disrupts the chemokine gradient through systemic exposure. P8A-CCL2 and WT induce CCR2 internalization in vitro and in vivo; CCR2 then recycles to the cell surface, but the cells remain refractory to chemotaxis in vitro for several hours. Although the response to P8A-CCL2 is similar to WT, this finding is novel and suggests that despite the presence of the receptor on the cell surface, coupling to the signaling machinery is retarded. In contrast to CCL2, P8A-CCL2 does not oligomerize on glycosaminoglycans (GAGs). However, it retains the ability to bind GAGs and displaces endogenous JE (murine MCP-1) from endothelial surfaces. Intravital microscopy studies indicate that P8A-CCL2 prevents leukocyte adhesion, while CCL2 has no effect, and this phenomenon may be related to the mechanism. These results suggest that oligomerization-deficient chemokines can exhibit anti-inflammatory properties in vivo and may represent new therapeutic modalities.