Th1-, Th2-, and Th17-related cytokine and chemokine receptor mRNA and protein expression in the brain tissues, T cells, and macrophages of dogs with necrotizing and granulomatous meningoencephalitis.

Necrotizing meningoencephalitis (NME), necrotizing leukoencephalitis (NLE), and granulomatous meningoencephalomyelitis (GME) are idiopathic inflammatory diseases in the central nervous system (CNS) of dogs. In our previous study, the proportion of inflammatory cells, except for CD3-positive T cells, were not different in parenchymal and perivascular lesions in the brain. However, breed specificities, clinical courses, and specific lesions were distinct among these diseases. Thus, similarities and differences in the pathologies of these diseases have been implied. In this study, the messenger RNA (mRNA) and/or protein expression levels of cytokines and chemokine receptors were investigated in NME (n = 2), NLE (n = 4), and GME (n = 2) cases, and their relationship in the formation of specific lesions was discussed. The mRNA and protein expression levels of interferon (IFN)-γ and interleukin (IL)-17 were marked in NME and GME, respectively. The mRNA expression levels of CXCR3 and CCR2 were also marked in NME and GME, respectively. The results of double-labeling immunofluorescence, used to identify cells producing IL-17 in these lesions, showed that most CD163-positive macrophages/microglia but fewer CD3-positive T cells were IL-17 positive in GME. These results indicate that IFN-γ plays a key role in NME lesions and that the macrophages/microglia that infiltrate brain lesions producing IL-17 are more important in GME than T cells.