Cot/tpl2 (MAP3K8) mediates myeloperoxidase activity and hypernociception following peripheral inflammation.

Cot/tpl2 (also known as MAP3K8) has emerged as a new and potentially interesting therapeutic anti-inflammatory target. Here, we report the first study of Cot/tpl2 involvement in acute peripheral inflammation in vivo. Six hours after an intraplantar injection of zymosan, Cot/tpl2(-/-) mice showed a 47% reduction in myeloperoxidase activity, concomitant with a 46% lower neutrophil recruitment and a 40% decreased luminol-mediated bioluminescence imaging in vivo. Accordingly, Cot/tpl2 deficiency provoked a 25-30% reduction in luminol-mediated bioluminescence and neutrophil recruitment together with a 65% lower macrophage recruitment 4 h following zymosan-induced peritonitis. Significantly impaired levels of G-CSF and GM-CSF and of other cytokines such as TNFα, IL-1ß, and IL-6, as well as some chemokines such as MCP-1, MIP-1ß, and keratinocyte-derived chemokine, were detected during the acute zymosan-induced intraplantar inflammatory response in Cot/tpl2(-/-) mice. Moreover, Cot/tpl2 deficiency dramatically decreased the production of the hypernociceptive ligand NGF at the inflammatory site during the course of inflammation. Most importantly, Cot/tpl2 deficiency significantly reduced zymosan-induced inflammatory hypernociception in mice, with a most pronounced effect of a 50% decrease compared with wild type (WT) at 24 h following intraplantar injection of zymosan. At this time, Cot/tpl2(-/-) mice showed significantly reduced NGF, TNFα, and prostaglandin E(2) levels compared with WT littermates. In conclusion, our study demonstrates an important role of Cot/tpl2 in the NGF, G-CSF, and GM-CSF production and myeloperoxidase activity in the acute inflammatory response process and its implication in inflammatory hypernociception.

Inducible nitric oxide synthase (iNOS) expression in autoimmune thyroid disorders (AITD).

INTRODUCTION: Nitric oxide is synthesized by different cell types through the action of the enzyme nitric oxide synthase (NOS). There are four isoforms of this enzyme: the neuronal, the endothelial, the mitochondrial, and the inducible (iNOS) forms. Although NO production may play an important role in the pathogenesis of inflammation and tissue damage, its possible role in autoimmune thyroiditis has not been adequately explored. OBJECTIVE: To study protein and mRNA expression of iNOS in human autoimmune thyroid disorders (AITD). PATIENTS AND METHOD: We evaluated the expression of iNOS in thyroid gland specimens from 10 patients with Graves' disease (GD), from five patients with Hashimoto's thyroiditis (HT) and from 10 controls by immunohistochemical and reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: Both immunohistochemistry and PCR techniques showed up-regulated expression of iNOS in the thyroid glands of patients with GD and HT. iNOS expression was higher in GD than in HT. In contrast, no iNOS expression was detected in normal thyroid tissue. In both GD and HT, iNOS was detected in thyrocytes, mainly in those localized in areas close to the inflammatory cell infiltrate. In addition, upregulated expression of iNOS was observed in endothelial cells and thyroidinfiltrating mononuclear cells in both GD and HT. CONCLUSIONS: The enhanced expression of iNOS in autoimmune thyroiditis suggests that NO synthesis may play an important role in the inflammatory phenomena and tissue damage observed in this disease.