Dominating interleukin-10 mRNA expression induction in cerebrospinal fluidcells of dogs with natural canine distemper virus induced demyelinating and non-demyelinating CNS lesions

Canine distemper virus (CDV) infection in dogs is commonly associated with demyelinating leukoencephalitis (DL). Although the mechanism of primary dem yelination in distemper remains undetermined recent studies showed a direct virus-induced cytolysis in early non-inflammatory and immune-mediated mech anisms in inflammatory lesions. To further investigate the pathogenesis of this morbillivirus-induced demyelination the expression of a variety of cyt okine mRNA species (interleukin (IL)-1 beta, IL-2, IL-6, IL-10, IL-12, tumo r necrosis factor (TNF)-alpha, transforming growth factor (TGF)-beta 1, and interferon (IFN)-gamma in cerebrospinal fluid cells of 12, dogs with CDV e ncephalitis was investigated employing reverse transcription-polymerase cha in reaction (RT-PCR) and these findings were correlated to the type of CNS lesions. Neuropathology revealed the whole spectrum of distemper DL lesions from acute to chronic alterations. however, most plaques lacked active dem yelination. Three control animals were devoid of any cytokine expression, w hereas in distemper animals IL-10 transcripts were found in nine dogs with acute and chronic lesions. IL-6, TNF, and TGF mRNA was found in six, four, and three animals, respectively. IL-12 and IFN-gamma, suggestive of a TH1-l ike dominated immune response, were detected only in one animal with chroni c lesions. Summarized, TNF and IL-6, associated with disease exacerbation, and IL-10 and TGF, indicative of remission, were often observed simultaneou sly in distemper DL and could not he assigned to a specific disease stage. However IL-10 mRNA remained the most frequently detected cytokine indicatin g a stage of inactivity in most animals investigated. (C) 1999 Elsevier Sci ence B.V. All rights reserved.