No abstract

Signals from the intestinal microbiota are important for normal host physiology; alteration of the microbiota (dysbiosis) is associated with multiple disease states. We determined the effect of antibiotic-induced intestinal dysbiosis on circulating cytokine levels and severity of ischemia/reperfusion injury in the heart. Treatment of Dahl S rats with a minimally absorbed antibiotic vancomycin, in the drinking water, decreased circulating leptin levels by 38%, resulted in smaller myocardial infarcts (27% reduction), and improved recovery of postischemic mechanical function (35%) as compared with untreated controls. Vancomycin altered the abundance of intestinal bacteria and fungi, measured by 16S and 18S ribosomal DNA quantity. Pretreatment with leptin (0.12 μg/kg i.v.) 24 h before ischemia/reperfusion abolished cardioprotection produced by vancomycin treatment. Dahl S rats fed the commercially available probiotic product Goodbelly, which contains the leptin-suppressing bacteria Lactobacillus plantarum 299v, also resulted in decreased circulating leptin levels by 41%, smaller myocardial infarcts (29% reduction), and greater recovery of postischemic mechanical function (23%). Pretreatment with leptin (0.12 μg/kg i.v.) abolished cardioprotection produced by Goodbelly. This proof-of-concept study is the first to identify a mechanistic link between changes in intestinal microbiota and myocardial infarction and demonstrates that a probiotic supplement can reduce myocardial infarct size.

Background:Angiogenesis, the growth of new blood vessels, is a critical homeostatic mechanism which regulates vascular populations in response to physiological requirements and pathophysiological demand, including chronic inflammation and cancer. The importance of angiogenesis in gastrointestinal chronic inflammation and cancer has been defined, as antiangiogenic therapy has demonstrated benefit in models of inflammatory bowel disease and colon cancer treatment. Curcumin is a natural product undergoing evaluation for the treatment of chronic inflammation, including inflammatory bowel disease (IBD). The effect of curcumin on human intestinal angiogenesis is not defined.Methods:The antiangiogenic effect of curcumin on in vitro angiogenesis was examined using primary cultures of human intestinal microvascular endothelial cells (HIMECs), stimulated with vascular endothelial growth factor (VEGF).Results:Curcumin inhibited proliferation, cell migration and tube formation in HIMECs induced by VEGF. Activation of HIMECs by VEGF resulted in enhanced expression of cyclo-oxygenase-2 (COX-2) mRNA, protein and prostaglandin E2 (PGE2) production. Pretreatment of HIMECs with 10 μM curcumin as well as 1 μM NS398, a selective inhibitor of COX-2, resulted in inhibition of COX-2 at the mRNA and protein level and PGE2 production. Similarly COX-2 expression in HIMECs was significantly inhibited by Jun N-terminal kinase (JNK; SP600125) and p38 mitogen-activated protein kinase (MAPK; SB203580) inhibitors and was reduced by p44/42 MAPK inhibitor (PD098059).Conclusions:Taken together, these data demonstrate an important role for COX-2 in the regulation of angiogenesis in HIMECs via MAPKs. Moreover, curcumin inhibits microvascular endothelial cell angiogenesis through inhibition of COX-2 expression and PGE2 production, suggesting that this natural product possesses antiangiogenic properties, which warrants further investigation as adjuvant treatment of IBD and cancer.

Erythropoietin is protective against cardiac ischemia, but the underlying mechanisms are unknown. We determined whether erythropoietin (0.5 - 10.0 U/ml) confers acute cardioprotection in infant rabbit hearts and the contribution of protein kinases, nitric oxide synthase and potassium channels to the underlying mechanism. Hearts from normoxic infant New Zealand White rabbits (n=8/group) were isolated and perfused in the Langendorff mode. Biventricular function was recorded under steady-state conditions prior to 30 min global no-flow ischemia and 35 min reperfusion. Administration of erythropoietin for 15 min immediately prior to ischemia resulted in a concentration-dependent increase in recovery of left and right ventricular developed pressure in rabbit hearts following myocardial ischemia and reperfusion. The optimal concentration of erythropoietin that afforded maximum recovery of developed pressure was manifest at 1.0 U/ml. Erythropoietin (1.0 U/ml) treatment resulted in phosphorylation of PKC, p38 MAP kinase and p42/44 MAP kinase. The cardioprotective effects of erythropoietin were abolished by the protein kinase inhibitors SB203580 (p38 MAP kinase), PD98059 (p42/44 MAP kinase) and chelerythrine (PKC) as well as the potassium channel blockers glibenclamide, HMR 1098, 5-HD and Paxilline. Nitrite and nitrate release from hearts before (2.3 +/- 0.9 nmol/min/g) and after (2.4 +/- 1.9 nmol/min/g) 15 min treatment with erythropoietin (1.0 U/ml) were not different. L-NAME and L-NMA did not block the cardioprotective effect of erythropoietin. We conclude the rapid activation of potassium channels and protein kinases by erythropoietin represents an important new mechanism for increasing cardioprotection.