Background-Activation of both type 1 and type 2 tumor necrosis factor (TNF) receptors (TNFR1 and TNFR2) confers cytoprotection in cardiac myocytes. Noting that the scaffolding protein TNF receptor-associated factor 2 (TRAF2) is common to both TNF receptors, we hypothesized that the cytoprotective responses of TNF were mediated through TRAF2. Methods and Results-Mice with cardiac-restricted overexpression of low levels of TNF (MHCsTNF 3 ) and TRAF2(MHC-TRAF2 LC ) and mice lacking TNFR1, TNFR2, and TNFR1/TNFR2 were subjected to ischemia (30 minutes) reperfusion (30 minutes) injury ex vivo using a Langendorff apparatus. MHCsTNF 3 mice were protected against ischemia-reperfusion injury as shown by a significant Ϸ30% greater left ventricular developed pressure, Ϸ80% lower creatine kinase release, and Evans blue dye uptake compared with littermates. The extent of ischemia-reperfusion induced injury was similar in wild-type, TNFR1, and TNFR2 deficient mice; however, mice lacking TNFR1/TNFR2 had a significant Ϸ40% lower left ventricular developed pressure, a Ϸ65% greater creatine kinase release, and Ϸ40% greater Evans blue dye uptake compared with littermates. Interestingly, MHC-TRAF2 LC mice had a significant Ϸ50% lower left ventricular developed pressure, a Ϸ70% lower creatine kinase release, and Ϸ80% lower Evans blue dye uptake compared with littermate controls after ischemia-reperfusion injury. Biochemical analysis of the MHC-TRAF2 LC hearts showed that there was activation of nuclear factor-kappaB but not c-Jun N-terminal kinase activation. Conclusion-Taken together, these results suggest that TNF confers cytoprotection in the heart through TRAF2-mediated activation of nuclear factor-B. (Circ Heart Fail. 2010;3:157-164.)

Production of proinflammatory cytokines contributes to cardiac dysfunction during ischemia-reperfusion. The principal mechanism responsible for the induction of this innate stress response during periods of myocardial ischemia-reperfusion remains unknown. Toll-like receptor 2 (TLR2) is a highly conserved pattern recognition receptor that has been implicated in the innate immune response to a variety of pathogens. However, TLR2 may also mediate inflammation in response to noninfectious injury. We therefore hypothesized that TLR2 is essential for modulating myocardial inflammation and left ventricular (LV) function during ischemia-reperfusion injury. Susceptibility to myocardial ischemia-reperfusion injury following ischemia-reperfusion was determined in Langendorff-perfused hearts isolated from wild-type mice and mice deficient in TLR2 (TLR2D) and Toll interleukin receptor domain-containing adaptor protein. After ischemia-reperfusion, contractile performance was significantly impaired in hearts from wild-type mice as demonstrated by a lower recovery of LV developed pressure relative to TLR2D hearts. Creatinine kinase levels were similar in both groups after reperfusion. Contractile dysfunction in wild-type hearts was associated with elevated cardiac levels of TNF and IL-1beta. Ischemia-reperfusion-induced LV dysfunction was reversed by treatment with the recombinant TNF blocking protein etanercept. These studies show for the first time that TLR2 signaling importantly contributes to the LV dysfunction that occurs following ischemia-reperfusion. Thus disruption of TLR2-mediated signaling may be helpful to induce immediate or delayed myocardial protection from ischemia-reperfusion injury.

Periostin (POSTN) interacts with multiple integrins to coordinate a variety of cellular processes, including epithelial-to-mesenchymal transition (EMT) and cell migration. In our previous study, anti-vascular endothelial growth factor A (VEGF-A) therapy was associated with resistance and EMT. The present study sought to determine the role of POSTN in the resistance of glioma stem cells (GSCs) to antiangiogenic therapy. In mouse xenograft models of human glioma, POSTN expression was associated with acquired resistance to anti-VEGF-A therapy and had a synergistic effect with bevacizumab in prolonging survival and decreasing tumor volume. Resistance to anti-VEGF-A therapy regulated by POSTN was associated with increased expression of transforming growth factor beta-1 (TGF beta1) and hypoxia-inducible factor-1 alpha (HIF1 alpha) in GSCs. At the molecular level, POSTN regulated invasion and expression of EMT (caveolin-1) and angiogenesis-related genes (HIF1 alpha and VEGF-A) through activation of signal transducer and activator of transcription 3 (STAT3). Moreover, recombinant POSTN increased GSC invasion. Collectively, our findings suggest that POSTN plays an important role in glioma invasion and resistance to antiangiogenic therapy.

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