Erythropoeitin Signaling in Macrophages Promotes Dying Cell Clearance and Immune Tolerance.

The failure of apoptotic cell clearance is linked to autoimmune diseases, nonresolving inflammation, and developmental abnormalities; however, pathways that regulate phagocytes for efficient apoptotic cell clearance remain poorly known. Apoptotic cells release find-me signals to recruit phagocytes to initiate their clearance. Here we found that find-me signal sphingosine 1-phosphate (S1P) activated macrophage erythropoietin (EPO) signaling promoted apoptotic cell clearance and immune tolerance. Dying cell-released S1P activated macrophage EPO signaling. Erythropoietin receptor (EPOR)-deficient macrophages exhibited impaired apoptotic cell phagocytosis. EPO enhanced apoptotic cell clearance through peroxisome proliferator activated receptor-γ (PPARγ). Moreover, macrophage-specific Epor(-/-) mice developed lupus-like symptoms, and interference in EPO signaling ameliorated the disease progression in lupus-like mice. Thus, we have identified a pathway that regulates macrophages to clear dying cells, uncovered the priming function of find-me signal S1P, and found a role of the erythropoiesis regulator EPO in apoptotic cell disposal, with implications for harnessing dying cell clearance.

ERK5/HDAC5-mediated, resveratrol-, and pterostilbene-induced expression of MnSOD in human endothelial cells.

SCOPE: Mitochondrial oxidative stress is closely correlated with numerous cardiovascular diseases. Manganese superoxide dismutase (MnSOD) is an important antioxidant enzyme in mitochondria. Although polyphenols can induce the expression of MnSOD, their corresponding mechanisms remains unclear. In this study, we tested the hypothesis that resveratrol and pterostilbene can activate the expression of MnSOD through an AMPK-ERK5/HDAC5-KLF2 pathway. METHODS AND RESULTS: Our results revealed that two stilbenes reduced mitochondrial superoxide-free radicals, and endothelial cell senescence, and increased the mRNA expression of several genes related to mitochondrial function, including MnSOD. Moreover, two stilbenes upregulated the activation of human MnSOD promoter luciferase reporter gene and protein level in human umbilical vein endothelial cells. Similarly, two stilbenes also stimulated LKB1, AMPKα, extracellular-signal related kinase 5 (ERK5) phosphorylation, and histone acetylase 5 (HDAC5) and Kruppel-like factor 2 (KLF2) expression. The knockdown of AMP-activated protein kinase (AMPK), ERK5, and HDAC5 by using short-hairpin RNA blocked pterostilbene-induced phosphorylation of their downstream signaling proteins and the expression of KLF2. Furthermore, using a chromatin immunoprecipitation-PCR detection method, we found that resveratrol and pterostilbene promoted KLF2 binding to CACCC sites of the human MnSOD promoter. CONCLUSION: Resveratrol and pterostilbene can activate MnSOD expression through ERK5/HDAC5 pathway, thus alleviating mitochondrial oxidative stress in endothelial cells that relates to cardiovascular disease.

Aortic Remodelling Is Improved by 2,3,5,4'-Tetrahydroxystilbene-2-O-ß-D-glucoside Involving the Smad3 Pathway in Spontaneously Hypertensive Rats.

Hypertension is a common health problem that substantially increases the risk of cardiovascular disease. The condition increases blood pressure, which causes alterations in vascular structure and leads to the development of vascular pathologies. 2,3,5,4'-Tetrahydroxystilbene-2-O-ß-D-glucoside (THSG), a resveratrol analogue extracted from a Chinese medicinal plant, has been proven to have numerous vascular protection functions. This study investigated whether THSG can improve vascular remodeling, which has thus far remained unclear. Orally administering THSG to spontaneously hypertensive rats (SHRs) aged 12 weeks for 14 weeks significantly inhibited intima-media thickness in the lower parts of the aortic arch, increased the vascular diastolic rate in response to acetylcholine, and reduced remodelling-related mRNA expression, such as that of ACTA2, CCL3, COL1A2, COL3A1, TIMP1 WISP2, IGFBP1, ECE1, KLF5, MYL1 BMP4, FN1, and PAI-1. Immunofluorescence staining also showed an inhibitory effect similar to that of THSG on PAI-1 protein expression in rat aortas. Results from immunoprecipitation and a Western blot assay showed that THSG inhibited the acetylation of Smad3. A chromatin immunoprecipitation assay showed that THSG prevented Smad3 binding to the PAI-1 proximal promoter in SHR aortas. In conclusion, our results demonstrated that the inhibitory effect of THSG on aortic remodelling involved the deacetylating role of Smad3 with increasing blood flow and with constant blood pressure.

Accumulation of connective tissue growth factor+ cells during the early phase of rat traumatic brain injury.

BACKGROUND: Glial scar formation is a common histopathological feature of traumatic brain injury (TBI). Astrogliosis and expression of transforming growth factor beta (TGF-ß) are key components of scar formation and blood-brain barrier modulation. Connective tissue growth factor (CTGF) is considered a cytokine mediating the effects of TGF-ß. METHODS: Here, we studied the CTGF expression in an open-skull weight-drop-induced TBI, with a focus on the early phase, most amenable to therapy. RESULTS: In normal rat brains of our study, CTGF+ cells were rarely observed. Significant parenchymal accumulation of CTGF+ non-neuron cells was observed 72 h post-TBI and increased continuously during the investigating time. We also observed that the accumulated CTGF+ non-neuron cells were mainly distributed in the perilesional areas and showed activated astrocyte phenotypes with typical stellate morphologic characteristics. CONCLUSION: Our observations demonstrated the time-dependent and lesion-associated accumulation of cellular CTGF expression in TBI, suggesting a pathological role of CTGF in TBI. VIRTUAL SLIDES: The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/3963462091241165.

2,3,5,4'-tetrahydroxystilbene-2-O-ß-d-glucoside ameliorates vascular senescence and improves blood flow involving a mechanism of p53 deacetylation.

BACKGROUND AND AIMS: 2,3,5,4'-tetrahydroxystilbene-2-O-ß-d-glucoside (THSG), a resveratrol analog with glucoside, has been shown in various studies to inhibit proliferation of vascular smooth muscle cells, attenuate inflammation, and prevent vascular endothelial dysfunction. In the study, we examined the effects of THSG on vascular senescence and blood flow. METHODS AND RESULTS: Oral administration of THSG for 14 weeks, resulted in notable increases in blood flow in spontaneously hypertensive rats (SHRs); and effective inhibition of vascular senescence as indicated by senescence-associated ß-galactosidase (SA-ß-gal) staining, phosphorylation of γH2AX observed by stain analysis of immunofluorescence, and K373 acetylation of p53 in the aortic arches of SHRs. Oral administration of THSG also induced eNOS expression and urinary NOx production. THSG weekly activated SIRT1 activity, stimulated eNOS promoter reporter gene activity, and ameliorated H(2)O(2)-induced cellular senescence and K373 acetylation of p53 in cultured human umbilical vein endothelial cells (HUVECs). CONCLUSIONS: THSG improves blood flow and ameliorates vascular senescence by increasing eNOS expression and Sirt1 activity and decreasing acetylation of p53 at K373 site, at least in part, both in vitro and in vivo.

Quercetin induces rapid eNOS phosphorylation and vasodilation by an Akt-independent and PKA-dependent mechanism.

Consumption of the flavonoid quercetin exerts beneficial effects on many chronic diseases. The mechanisms involved in the vasorelaxant effect of quercetin remain uncertain. In the present study, we examined the role of quercetin in vasodilation and rapid endothelial nitric oxide synthase (eNOS) activity in endothelial cells. Quercetin induced a rapid, dose-dependent phosphorylation of eNOS at serine 1179. PKA, Akt and ERK1/2 were all quickly phosphorylated in the process too, but not AMPK and CaMK II. The specific kinase inhibitors for Akt or ERK1/2 could not abolish the quercetin-induced eNOS phosphorylation at Ser1179, which, however, was significantly abolished by H89, an inhibitor of PKA. Concomitantly, intracellular cAMP production was quickly increased by quercetin stimulation and an adenylate cyclase activator, forskolin, also induced eNOS phosphorylation at Ser1179. Quercetin enhanced nitric oxide (NO) production, which was abolished by an eNOS inhibitor, L-NAME or H89. Quercetin exerted a vasodilatory effect on rings with an intact endothelium but not on endothelium-deprived rings, and also inhibited vascular contractility induced by angiotensin II or phenylephrine in rat aortic rings. We conclude that quercetin quickly phosphorylates eNOS at Ser1179 via an Akt-independent, cAMP/PKA-mediated pathway to enhance the production of NO and to promote vasodilation.