Minimal interleukin expression in canine intracranial meningiomas.

Context The propagation of meningiomas has been linked with several inflammatory interleukins (ILs). Human meningioma cells have been found to synthesise and secrete IL-6, as well as to express IL-8 mRNA. The aim of this study was to determine whether canine intracranial meningiomas express IL-6 and/or IL-8. Main conclusion The limited IL-6 expression and lack of IL-8 expression indicated that IL-6 and IL-8 inhibitors were unlikely to be beneficial for the treatment of canine meningiomas. The limited IL expression may be because of species differences, fewer high-grade tumours or sample size. Approach Nineteen surgically excised formalin-fixed, paraffin-embedded canine intracranial meningioma biopsy samples were collected. Immunohistochemical detection of IL-6 and IL-8 was performed by an automated staining system using anti-canine IL-6 and anti-canine IL-8 monoclonal antibodies, respectively. To quantify IL-6 and IL-8, staining of the entire meningioma section was evaluated for percentage of cells positively stained and their staining intensity. The percentage of cells positively stained was recorded as: 0 per cent of cells stained; 1 to 30 per cent of cells stained; 31 to 60 per cent of cells stained; and 61 to 100 per cent of cells stained. Staining intensity was subjectively recorded as: 0, negative expression; 1, weak expression; 2, moderate expression; and 3, marked expression. Results Of the 19 tumour samples, staining for IL-6 expression was positive in five samples and IL-8 expression was positive in zero samples. IL-6 staining in the positive tumour samples was seen as diffusely cytoplasmic. In all five IL-6 positively stained samples, the percentage staining area was greater than 61 per cent; two of the five positive samples had weak staining intensity, while the remaining three positive samples had moderate staining intensity. Interpretation The limited IL-6 expression and lack of IL-8 expression indicates that IL-6 and IL-8 inhibitors are unlikely to be beneficial for the treatment of canine meningiomas. However, it should be noted that a failure to detect an antigen with immunohistochemistry may not be equivalent to a lack of expression. Significance of findings This study showed that the role of ILs in the pathophysiology of canine intracranial meningiomas seems to be limited. [ABSTRACT FROM AUTHOR]