Pathological Findings in Gastrointestinal Neoplasms and Polyps in 860 Cats and a Pilot Study on miRNA Analyses.

Background: Gastrointestinal masses in cats are of clinical relevance, but pathological studies with larger case numbers are lacking. Biomarkers such as miRNA have not yet been investigated in feline intestinal neoplasms. Methods: A retrospective analysis of pathology reports included 860 feline gastrointestinal masses. Immunohistochemistry was performed on 91 lymphomas, 10 sarcomas and 7 mast cell tumours (MCT). Analyses of miRNA-20b and miRNA-192 were performed on 11 lymphomas, 5 carcinomas and 5 control tissues by ddPCR. Results: The pathological diagnosis identified 679 lymphomas, 122 carcinomas, 28 sarcomas, 23 polyps, 7 MCT and 1 leiomyoma. Carcinomas and polyps were most commonly found in the large intestine, lymphomas were most commonly found in the stomach and small intestine and MCT only occurred in the small intestine. Besides the well-described small-cell, mitotic count <2 T-cell lymphomas and the large-cell B-cell lymphomas with a high mitotic count, several variants of lymphomas were identified. The values of miRNA-20b were found to be up-regulated in samples of all types of cancer, whereas miRNA-192 was only up-regulated in carcinomas and B-cell lymphomas. Conclusions: The histopathological and immunohistochemical (sub-)classification of feline intestinal masses confirmed the occurrence of different tumour types, with lymphoma being the most frequent neoplasm. Novel biomarkers such as miRNA-20b and miRNA-192 might have diagnostic potential in feline intestinal neoplasms and should be further investigated.

Antiphospholipid antibodies induce translocation of TLR7 and TLR8 to the endosome in human monocytes and plasmacytoid dendritic cells.

The antiphospholipid syndrome (APS) is an autoimmune disease characterized by thromboembolic events and/or fetal loss in the presence of antiphospholipid antibodies (aPLs). The mechanisms underlying the pathogenicity of aPLs are still poorly understood. Here we show that 3 human monoclonal aPLs as well as IgG fractions from patients with the APS increase mRNA expression of the intracellular toll-like receptor (TLR) 7 in plasmacytoid dendritic cells and TLR8 in monocytes. Simultaneously they induce the translocation of TLR7 or TLR8 from the endoplasmic reticulum to the endosome. These effects depend on the uptake of aPLs into the endosome, subsequent activation of endosomal NADPH oxidase, and generation of superoxide. As a consequence cells are dramatically sensitized to ligands for TLR7 and TLR8. This observation delineates a novel signal transduction pathway in innate immunity originating from the endosome. Because the overexpression of TLR7 can also be detected in plasmacytoid dendritic cells from patients with the APS ex vivo, our results provide an explanation for proinflammatory and procoagulant effects of aPLs. Because inappropriate expression of TLR7 has been implicated in the development of systemic autoimmunity, these findings may also be relevant for the understanding of autoimmunity.

The roll of Toll-like receptors in the antiphospholipid syndrome.

The antiphospholipid syndrome (APS) is an autoimmune disease characterized by thrombosis, recurrent fetal loss, and the presence of antiphospholipid antibodies (aPL). Recent data support the idea that the thrombotic activity in APS patients is attributed to enhanced cytokine release via activation of certain Toll-like receptors. To investigate these mechanisms more precisely, different experimental approaches were used to investigate this connection in detail. IgG fractions and/or monoclonal aPL, either generated from murine or human B cells were intensely used for stimulation experiments of monocytes, endothelial cells, or dendritic cells. All these stimuli induced an enhanced expression and secretion of cytokines, especially tumor necrosis factor (TNF)-alpha, caused by specific regulation or activation of Toll-like receptors. Using specific agonists or inhibitors could confirm the causal connection of these stimulatory effects. This review focuses on these recent developments, connecting the binding of aPL with the activity of Toll-like receptors, especially in monocytes, endothelial cells, and dendritic cells.

Human antiphospholipid antibodies induce TNFalpha in monocytes via Toll-like receptor 8.

The antiphospholipid syndrome (APS) is characterized by recurrent arterial and/or venous thromboses, pregnancy loss and the presence of antiphospholipid antibodies (aPL). One of the discussed mechanisms of this thrombotic activity in APS patients is attributed to TNFalpha secretion in monocytes after aPL stimulation. To investigate this mechanism in detail, we employed a monoclonal aPL and IgG fractions of APS patients for stimulation of human peripheral monocytes. Stimulation with this monoclonal aPL resulted in an increased expression and secretion of TNFalpha, caused by specific upregulation of TLR8 mRNA and protein expression levels. To confirm the specificity of this finding we could demonstrate that the TNFalpha enhancement could be neutralized by a TLR8-specific inhibitory DNA-oligonucleotide and could be further increased by adding the specific ligands for TLR8. Using APS patients IgG fractions for stimulation of peripheral monocytes revealed a similar TLR8 mRNA elevation and increase in TNFalpha-production. Furthermore the TLR8 expression level in PBMC's of APS patients was as well significantly elevated. It could be demonstrated that the TNFalpha release in monocytes resulting from aPL stimulation was exclusively induced by TLR8 engagement. This could be confirmed in PBMC's of APS patients, hinting that endogenous stimulation of TLR8 in APS patients and consecutive elevation of TNFalpha promotes a proinflammatory environment.