Status of proinflammatory and anti-inflammatory cytokines in different brain regions of a rat model of Japanese encephalitis.

OBJECTIVES: This study evaluated cytokines and chemokine in different regions of the rat brain at different time points following Japanese encephalitis virus (JEV) infection. DESIGN: Twelve-day-old Wistar rats were infected by intracerebral inoculation of 3 × 10(6) plaque-forming units of JEV 78668A strain. Expression of cytokines and chemokine was assayed using cytokine bead array in different regions of the brain at 3, 6, 10 and 20 days post-inoculation (dpi). Pathological changes including immunohistochemistry for JEV antigen were observed. RESULTS: The cytokine levels were increased in the acute stage and declined on follow-up. In the acute stage (6 dpi), the levels of TNF-α, IFN-γ, IL-6 and IL-10 were maximum in the cortex, whereas the level of IL-4 was maximum in the striatum. Lower levels of these cytokines were observed in mid-brain and thalamus compared to other regions studied. Maximum expression of JEV antigen and histopathological changes as well as cytokines and chemokine were observed at 6 dpi in all the brain regions studied, but declined thereafter. CONCLUSION: This experimental study revealed maximum expression of cytokines and chemokine at 6 dpi of JEV infection which corresponded with histopathological changes in different brain regions.

Sequential changes in serum cytokines and chemokines in a rat model of Japanese encephalitis.

OBJECTIVES: The mechanisms underlying inflammation and immune responses in viral encephalitis are not fully understood. Therefore, in the present study we aimed to investigate the cytokine and chemokine levels in Japanese encephalitis virus (JEV)-infected rats. METHODS: Twelve-day-old Wistar rats were infected with 3 x 10(6) plaque-forming units of JEV intracerebrally. Cytokine and chemokine levels were analyzed in serum 3, 6, 10 and 20 days post inoculation (dpi). RESULTS: There were increased levels of proinflammatory and anti-inflammatory cytokines and a chemokine (monocyte chemoattractant protein-1) in the serum of rats after JEV infection compared to controls. The levels of cytokines and chemokine peaked at 10 dpi and had declined significantly by 20 dpi. The neurological deficit also increased in the acute stage of disease and partially recovered thereafter. CONCLUSION: Serum cytokine and chemokine levels decline at 10 dpi and do not significantly correlate with neurological dysfunction.

Assessment of World Health Organization definition of dengue hemorrhagic fever in North India.

BACKGROUND: Classification of symptomatic dengue according to current World Health Organization (WHO) criteria is not straightforward. In this prospective study of dengue infection during an epidemic in India in 2004, we applied the WHO classification of dengue to assess its usefulness for our patients. METHODOLOGY: The study included 145 clinically suspected cases of dengue infection of all ages. Dengue was confirmed by serological methods (IgM ELISA and HI test). WHO criteria were applied to classify dengue positive patients into Dengue Fever (DF), Dengue Hemorrhagic Fever (DHF) and Dengue Shock Syndrome (DSS). Clinical and laboratory parameters were compared between dengue patients with bleeding and those without bleeding. RESULTS: Out of the 50 serologically positive cases of dengue enrolled in the study, only 3 met the WHO criteria for DHF and 1 met the criteria for DSS; however, 21 (42%) cases had one or more bleeding manifestations. CONCLUSION: By using WHO criteria of DHF on Indian patients, all severe cases of dengue cannot be correctly classified. A new definition of DHF that considers geographic and age-related variations in laboratory and clinical parameters is urgently required.

A study of motor activity and catecholamine levels in different brain regions following Japanese encephalitis virus infection in rats.

Japanese encephalitis (JE) is associated with a variety of movement disorders including transient form of pakinsonian features, dystonia and miscellaneous movement disorders. The neurotransmitters have important role in movement disorders. However their role in different brain regions in relation to behavioral activities in animal model of JE is not understood. The present study was aimed to investigate the behavioral parameters, the levels of catecholamine in brain regions--thalamus, midbrain, corpus striatum and frontal cortex on 0, 10 and 20 days post inoculation (dpi) with histopathological observations. Twelve day old Wistar strain rats were inoculated intracerebrally with a dose of 3 x 10(6) pfu of JE virus. Spontaneous locomotor activity (SLA) and grip strength were monitored. The levels of catecholamine were estimated using HPLC-ECD and histopathological changes were observed using haematoxylin and eosine staining. A significant decrease in SLA and grip strength was observed in JEV infected rats as compared to controls on 10 and 20 dpi. The levels of norepinephrine, dopamine, 3,4-dihydroxyphenylacetic acid, homovanillic acid, and serotonin were significantly decreased in all the brain regions studied with respect to controls. We did not find significant recovery in catecholamine levels and locomotor activities up to 20 dpi and any significant correlation between behavioral changes and neurotransmitter levels. However histopathological studies revealed mild reduction in degree of damage on 20 dpi. The present study demonstrates the involvement of different brain regions in altered locomotor activity which may be associated with reduction in catecholamine levels in rat model of JE.

Imbalance in oxidant/antioxidant system in different brain regions of rat after the infection of Japanese encephalitis virus.

The imbalance in redox equilibrium is associated with several viral diseases however its role in Japanese encephalitis (JE) has not been reported. In the present study, we report the status of oxidant/antioxidant system in different brain regions in rat model of JE. Twelve days old Wistar strain rats were inoculated intracerebrally with a dose of 3x10(6)pfu of JE virus (JEV). The activity of manganese superoxide dismutase (Mn-SOD), catalase (CAT), glutathione peroxidase (GPx) and the levels of reduced glutathione (GSH) and malonaldialdehyde (MDA) were estimated in corpus striatum, frontal cortex, thalamus and midbrain on 0, 10 and 20 days post-inoculation (dpi). A significant increase in MDA levels in striatum (p<0.01), cortex (p<0.01), thalamus (p<0.01) and midbrain (p<0.01) was observed in JEV infected rats on 10 and 20dpi compared to controls. The activity of CAT, GPx and the levels of GSH were significantly decreased in all the brain regions studied on 10 and 20dpi compared to controls. However, the activity of Mn-SOD in striatum (p<0.01), cortex (p<0.05), thalamus (p<0.01) and midbrain (p<0.01) were significantly increased on 10 and 20dpi in JEV infected rats compared to controls. The activity of Mn-SOD and MDA levels were significantly increased whereas the activity of CAT, GPx and GSH levels were significantly decreased in all the brain regions studied as the disease progressed from 0 to 20dpi. The maximum alteration in oxidant/antioxidant balance was observed in thalamus and midbrain. The results of the present study demonstrate that antioxidant defense mechanism is impaired after the infection of JE virus suggesting its critical role in cellular injury in brain regions. The findings could be beneficial to understand the role of oxidative stress in the pathogenesis of JE and therapeutic interventions.

Free radical generation by neurons in rat model of Japanese encephalitis.

Increased generation of free radicals resulting in brain injury is a feature of many viral infections. The present study has been undertaken to evaluate the level of free radicals in Japanese encephalitis. Twelve days old Wistar rats were inoculated intracerebrally with 3 x 10(6) pfu of JE virus and were sacrificed on 3, 6, 10, and 20 days post inoculation (dpi). The neuronal levels of reactive oxygen species (ROS), nitric oxide (NO), peroxinitrite (OONO(-)), necrotic and apoptotic cell population were estimated by flow cytometry. Hematoxylin-eosin staining was also performed. Maximum level of neuronal ROS and OONO(-) was observed on 6 dpi; however, NO levels peaked on 10 dpi. Free radical generation significantly declined on 20 dpi as compared to control. Apoptotic cell death gradually increased over the time. Neuronal shrinkage and necrosis was also observed. The results of our study indicate that free radicals increased in acute JE and declined at later stage, which may contribute to cell death.

Some observations on the tropism of Japanese encephalitis virus in rat brain.

The clinical picture of viral encephalitis is determined by the affinity and persistence of the virus to different brain regions. Therefore, the present study was aimed to investigate the neuropathological changes following Japanese encephalitis virus (JEV) infection in rat at different time points. Twelve days old Wistar rats were infected by intracerebral inoculation of JEV. Presence of JEV antigen was detected in thalamus, striatum, cortex and mid brain on 3, 6, 10 and 20 days post inoculation (d.p.i.). Histopathological changes were also studied in different brain regions at different time points. The highest expression of JEV antigen was found on 6 dpi in all the brain regions studied. JEV antigen was maximum in thalamus on 6 d.p.i. and mid brain on 10 d.p.i. JEV antigen, however, was almost undetectable on 20 d.p.i. in all the regions. The classical pathological changes such as cellular infiltration, perivascular cuffing, meningeal disruption, neuronal damage, neuronal shrinkage, and plaque formation were observed up to 10 d.p.i. The present study reveals high affinity of JEV to thalamus, brainstem and striatum. Rat model of JEV infection may serve as a useful model for studying mechanism of cell injury and recovery in JE.