Chemokines are produced in the brain early during the course of experimental African trypanosomiasis.

African trypanosomiasis is characterized by progressive central nervous system (CNS) involvement. Using single and double immunohistochemistry, we evaluated the induction of alpha- and beta-chemokines in brains of Sprague-Dawley rats infected with Trypanosoma brucei brucei (T. b. brucei) and identified their cellular source. The results showed high production of MIP-2, RANTES and MIP-1alpha and to a lower extend MCP-1 in infected animals compared to controls. MIP-2, RANTES and MIP-1alpha were produced early by astrocytes and microglia and later by macrophages and T-cells. These findings suggest that chemokines may contribute to the immunopathogenesis that occurs in the CNS early during infections.

Trypanosoma brucei brucei induces interferon-gamma expression in rat dorsal root ganglia cells via a tyrosine kinase-dependent pathway.

Dorsal root ganglia (DRG) were shown to express neuronal interferon (IFN)-gamma, which supports Trypanosoma brucei brucei growth. The ability of a trypanosome-derived factor (TLTF) to activate DRG to neuronal IFN-gamma secretion was investigated, together with the signaling pathway that might be involved during this process. Immunohistochemical staining revealed expression of neuronal IFN-gamma on stimulation with TLTF, which was blocked with the tyrosine protein-kinase inhibitor, tyrphostin A47. Western blot was used to analyze DRG lysates prepared at different time points after stimulation with TLTF. A tyrosine-phosphorylated protein induced at 15 min was seen as a band of 120-150 kDa, followed by a decrease to control levels after 30 min. A47 greatly suppressed the TLTF-induced tyrosine protein kinase activity. In addition, evidence suggesting that the transcription factor STAT-1 may play a key role in the TLTF signaling pathway was provided by the blocking effects of A47 on STAT-1 translocation to the nucleus.

Cytokine profiles in the central nervous system and the spleen during the early course of experimental African trypanosomiasis.

Cytokines are important signalling proteins, which have been shown to contribute to immunopathogenesis of several inflammatory and infectious diseases such as African trypanosomiasis. The present study was conducted in order to evaluate the early induction of five potential cytokines in the central nervous system (CNS) and spleens from Trypanosoma brucei brucei (T. b. brucei)-inoculated and uninfected control Sprague-Dawley rats. In brain, choroid plexus and spleen, cytokine levels were examined by in situ hybridization and immunohistochemistry, while ELISA was used to measure cytokine levels in cerebrospinal fluid (CSF). Our results showed that interferon (IFN)-gamma and transforming growth factor (TGF)-beta were highly expressed in all compartments, but low interleukin (IL)-4, IL-10 and tumour necrosis factor (TNF)-alpha mRNA levels were registered. The pattern of these cytokines is in context with the severity of the disease because (i) IFN-gamma was previously demonstrated to promote parasite growth (ii) TNF-alpha was previously demonstrated to kill the parasites and (iii) IL-4 was previously demonstrated to promote antibody production necessary for elimination of the infection. These data support the hypothesis that cytokines may have a role in developing the disease either by enhancing the parasite growth or by suppressing the immune response.

Coordinate up-regulation of the beta-chemokine subfamily in autoimmune sialoadenitis of MRL/lpr mice.

Mononuclear cell (MNC) infiltration of the salivary and lacrimal glands is a major feature in Sjogren's syndrome (SS) and its animal model, murine autoimmune sialoadenitis (MAS). To investigate factors that influence selective infiltration by MNC of submandibular glands in young and adult MRL/lpr mice with MAS, expression of mRNA encoding the beta-chemokines monocyte chemoattractant protein (MCP)-1, macrophage inflammatory protein (MIP)-1alpha, MIP-1beta and regulated upon activation, normal T-cell expressed and secreted (RANTES) was investigated by in situ hybridization. MCP-1 protein production was also evaluated by immunohistochemistry. Young mice with MAS showed an early up-regulation of mRNA expression for MCP-1, MIP-1beta and RANTES, while MIP-1alpha mRNA expression was not affected. Adult mice with MAS showed a further up-regulation of mRNA expression for MCP-1, MIP-1beta and RANTES, and a remarkably strong up-regulation for MIP-1alpha. Immunohistochemistry revealed that MCP-1 protein production paralleled MCP-1 mRNA expression in both young and adult mice. These observations implicate MCP-1, MIP-1beta and RANTES as potential chemokines in induction of MAS, and MCP-1, MIP-1beta, RANTES and prominently MIP-1alpha in progression and perturbation of MAS.