Mediating delta-opioid-initiated heart protection via the beta2-adrenergic receptor: role of the intrinsic cardiac adrenergic cell.

Stimulation of cardiac beta(2)-adrenergic receptor (beta(2)-AR) or delta-opioid receptor (DOR) exerts a similar degree of cardioprotection against myocardial ischemia in experimental models. We hypothesized that delta-opioid-initiated cardioprotection is mediated by the intrinsic cardiac adrenergic (ICA) cell via enhanced epinephrine release. Using immunohistochemical and in situ hybridization methods, we detected in situ tyrosine hydroxylase (TH) mRNA and TH immunoreactivity that was colocalized with DOR immunoreactivity in ICA cells in human and rat hearts. Western blot analysis detected DOR protein in ICA cells isolated from rat ventricular myocytes. The physiology of DOR expression was examined by determining changes of cytosolic Ca(2+) concentration ([Ca(2+)](i)) transients in isolated rat ICA cells using fluorescence spectrophotometry. Exposing the selective delta-opioid agonist D-[Pen(2,5)]enkephalin (DPDPE) to ICA cells increased [Ca(2+)](i) transients in a concentration-dependent manner. Such an effect was abolished by the Ca(2+) channel blocker nifedipine. HPLC-electrochemical detection demonstrated a 2.4-fold increase in epinephrine release from ICA cells following DPDPE application. The significance of the ICA cell and its epinephrine release in delta-opioid-initiated cardioprotection was demonstrated in the rat myocardial infarction model and ICA cell-ventricular myocyte coculture. DPDPE administered before coronary artery occlusion or simulated ischemia-reperfusion reduced left ventricular infarct size by 54 +/- 15% or myocyte death by 26 +/- 4%, respectively. beta(2)-AR blockade markedly attenuated delta-opioid-initiated infarct size-limiting effect and abolished delta-opioid-initiated myocyte survival protection in rat ICA cell-myocyte coculture. Furthermore, delta-opioid agonist exerted no myocyte survival protection in the absence of cocultured ICA cells during ischemia-reperfusion. We conclude that delta-opioid-initiated myocardial infarct size reduction is primarily mediated via endogenous epinephrine/beta(2)-AR signaling pathway as a result of ICA cell activation.

Distribution and phenotype of Epstein-Barr virus-infected cells in human pharyngeal tonsils.

Although Epstein-Barr virus (EBV) is often found in human tonsils, it remains to be precisely determined in what cells and microenvironment the virus is present. Although generally regarded as a B lymphotropic virus, EBV is associated with non-B-cell tumors, for example, NK/T-cell lymphoma, carcinoma, and leiomyosarcoma. To provide a basis for understanding the origin and biology of EBV-infected non-B cells, the immunophenotype of all EBV-infected cells in reactive human tonsils was determined by subjecting tonsil sections to dual/triple EBER in situ hybridization and immunohistochemistry with monoclonal antibodies to T cells (CD3, CD4, CD8, CCR3), B cells (CD20), plasma cells (CD138), natural killer (NK) cells (PEN5), and epithelial cells (cytokeratin), as well as frozen section immunostaining with antibodies to EBV latent proteins EBNA1, EBNA2, LMP1, and EBV early protein BZLF1. Most tonsils contained nearly equal numbers of EBNA1- and LMP1-positive cells (latency program) while only a few contained EBNA2-positive cells (growth program). More than 1000 EBER-positive cells from six tonsils were detected in the interfollicular zone (59%), tonsillar crypts (26%), and follicles (15%). Most (82%) EBER-positive cells are CD20-positive B cells, 7% are CD3-positive T cells, and 11% are cells of indeterminate lineage, often with plasmacytoid morphology. However, no EBER-positive plasma cells were identified. Rare EBER-positive NK cells and EBER/BZLF1-positive epithelial cells were identified. The direct demonstration of EBV within rare T cells, NK cells, and epithelial cells in reactive human tonsils provide a basis for further understanding of the origin of EBV-associated tumors of non-B-cell type.