Rationale: TGF (transforming growth factor)-β is critically involved in myocardial injury, repair, and fibrosis, activating both Smad (small mothers against decapentaplegic)-dependent and non-Smad pathways. The in vivo role of TGF-β signaling in regulation of macrophage function is poorly understood. We hypothesized that in the infarcted myocardium, activation of TGF-β/Smad signaling in macrophages may regulate repair and remodeling. Objective: To investigate the role of macrophage-specific TGF-β Smad3 signaling in a mouse model of myocardial infarction and to dissect the mechanisms mediating Smad-dependent modulation of macrophage function. Methods and Results: TGF-βs markedly activated Smad3 in macrophages, without affecting Smad-independent pathways. Phagocytosis rapidly and directly activated macrophage Smad3, in the absence of active TGF-β release. MyS3KO (myeloid cell–specific Smad3 knockout) mice had no baseline defects but exhibited increased late mortality and accentuated dilative postmyocardial infarction remodeling. Adverse outcome in infarcted MyS3KO mice was associated with perturbations in phagocytic activity, defective transition of macrophages to an anti-inflammatory phenotype, scar expansion, and accentuated apoptosis of border zone cardiomyocytes. In vitro, Smad3 null macrophages exhibited reduced expression of genes associated with eat-me signals, such as Mfge8 (milk fat globule-epidermal growth factor factor 8), and reduced capacity to produce the anti-inflammatory mediators IL (interleukin)-10 and TGF-β1, and the angiogenic growth factor VEGF (vascular endothelial growth factor). Mfge8 partly rescued the phagocytic defect of Smad3 null macrophages, without affecting inflammatory activity. Impaired anti-inflammatory actions of Smad3 null macrophages were associated with marked attenuation of phagocytosis-induced PPAR (peroxisome proliferator-activated receptor) expression. MyS3KO mice had no significant alterations in microvascular density and interstitial fibrosis in remodeling myocardial segments. Conclusions: We demonstrate that Smad3 critically regulates function of infarct macrophages, by mediating acquisition of a phagocytic phenotype and by contributing to anti-inflammatory transition. Smad3-dependent actions in macrophages protect the infarcted heart from adverse remodeling.

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This experiment was conducted with 144 male Arbor Acre broilers (one d old, weighing 45.6 ± 1.3 g) to determine protective effects of Forsythia suspensa extract (FSE) against breast muscle oxidative injury induced by transport stress (TS). The birds were randomly allotted to one of 4 treatments in a 2 × 2 factorial arrangement. The treatments consisted of broilers fed diets supplemented without or with FSE (100 mg/kg) and challenged without or with TS for 3 h before slaughter. Transport stress increased live BW loss of broilers (P < 0.05), and the adverse effect was attenuated by FSE (P < 0.05). Serum levels of corticoserone and lactate were increased for broilers after transportation (P < 0.05), whereas these parameters were not affected by FSE. After slaughter, neither breast muscle pH value at 45 min and 24 h postmortem nor 24 h drip loss value was influenced by TS or FSE, whereas TS increased the value of pH decline within 24 h postmortem (P < 0.05). Transportation decreased redness and increased yellowness value of breast muscle in broilers (P < 0.05), and FSE tended to have (P = 0.06) or had the converse changes (P < 0.05). Comparing with non-transported birds, the birds subjected to transportation had greater malondialdehyde (MDA) content and avUCP mRNA expression (P < 0.05) and lower 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical scavenging activity (P < 0.05) in breast muscle, whereas the birds supplemented with FSE had lower MDA content (P < 0.05) and greater DPPH radical scavenging activity (P < 0.05). Transport caused decreases (P < 0.05) in total antioxidant capacity and glutathione peroxidase activity, and the decreases were improved by FSE (P < 0.05). Collectively, live BW loss and breast muscle oxidative injury were increased by TS in broilers and could be attenuated by FSE via directly scavenging free radicals and increased antioxidant capacity. Therefore, FSE could protect broilers against breast muscle oxidative injury induced by TS.