The Effects of Mangiferin (Mangifera indica L) in Doxorubicin-induced Cardiotoxicity in Rats.

AIM: The cardiotoxicity effect of doxorubicin (DOX), a widely used antitumor agent has restricted its clinical application. The aim of the current study was to explore the potential protective effect of mangiferin, a naturally occurring glucosylxanthone, that have antioxidant activity by its iron-complexing ability in mitochondria, against DOX-induced cardiac toxicity in rats in comparison with other antioxidants namely Sylimarin (SYL) and Vitamin E (VitE). METHODS: Mangiferin was given orally to rats at a dose of 50, and 100 mg/kg for 5 weeks, and DOX was injected at a total dose of 15 mg/kg. Cardiac toxicity was evaluated by lactate dehydrogenase and creatine kinase in the serum, malondialdehyde (MDA) level in plasma and cardiac tissue, and antioxidant enzyme superoxide dismutase (SOD) in cardiac tissue. RESULTS: Mangiferin protected against DOX-induced increased mortality and electrocardiogram abnormality and decreased biochemical markers of cardiac toxicity i. e., lactate dehydrogenase and creatine phosphokinase isoenzyme. In addition, elevation of plasma and cardiac tissue levels of MDA in response to DOX treatment were significantly attenuated. The reduction of cardiac activity of SOD was significantly reduced in contrast with the other antioxidant SYL and Vit E. Histopathologically, mangiferin treatment showed significant reduction in inflammatory cell number, fibrotic area, and necrotic foci as compared with DOX only-treated rats. CONCLUSION: These results suggested that mangiferin had better protective effect against DOX-induced cardiac toxicity in comparison with SYL and VitE, thus besides the antioxidant activity, different mechanism may be involved in the action of mangiferin and need to be clarified in the future studies.

Immunophenotypical characterization of macrophages in rat bleomycin-induced scleroderma.

Scleroderma is a skin disorder characterized by persistent fibrosis. Macrophage properties influencing cutaneous fibrogenesis remain to be fully elucidated. In this rat (F344 rats) model of scleroderma, at 1, 2, 3, and 4 weeks after initiation of daily subcutaneous injections of bleomycin (BLM; 100 µl of 1 mg/ml daily), skin samples were collected for histological and immunohistochemical evaluations. Immunohistochemically, the numbers of cells reacting to ED1 (anti-CD68; phagocytic activity) and ED2 (anti-CD163; inflammatory factor production) began to increase at week 1, peaked at week 2, and decreased thereafter. In contrast, the increased number of cells reacting to OX6 (anti-MHC class II molecules) was seen from week 2 and remained elevated until week 4. α-Smooth muscle actin-positive myofibroblasts were increased for 4 weeks. Double labeling revealed that galectin-3, a regulator of fibrogenic factor TGF-ß1, was expressed in CD68+, CD163+, and MHC class II+ macrophages and myofibroblasts. mRNA expression of TGF-ß1, as well as MCP-1 and CSF-1 (both macrophage function modulators), were significantly elevated at weeks 1 to 4. This study shows that the increased number of macrophages with heterogeneous immunophenotypes, which might be induced by MCP-1 and CSF-1, could participate in the sclerotic lesion formation, presumably through increased fibrogenic factors such as galectin-3 and TGF-ß1; the data may provide useful information to understand the pathogenesis of the human scleroderma condition.

Distribution of cells labelled by a novel somatic stem cell-recognizing antibody (A3) in pulmonary genesis and bleomycin induced pulmonary fibrosis in rats.

Stem cells play important roles in organogenesis and remodelling after tissue injury. A monoclonal antibody (A3) has been produced against rat somatic stem cells. The present study investigated the distribution of cells labelled by A3 in the lung of fetal, neonatal and adult rats, as well as in the lung of rats with bleomycin (BLM) induced pulmonary fibrosis. In developing fetal lungs, A3(+) interstitial cells were present around the bronchi/bronchioles and arterioles, while in neonatal and adult lungs, the A3 reactivity of the interstitial cells gradually disappeared and instead, vascular endothelial cells in alveolar capillaries and arterioles expressed A3. By double immunofluorescence labelling, the A3(+) interstitial cells also expressed vimentin (a mesenchymal marker) and CD34 (a marker of immature mesenchymal cells), indicating that the interstitial cells were immature mesenchymal cells concentrated in organs as precursors to cells of connective tissues. A3(+)endothelial cells were co-expressed RECA-1 (a marker of rat endothelial cells) and A3 was localized to the cell membrane and cytoplasm of these cells by immunoelectron microscopy. In BLM induced fibrotic lesions, there were many A3(+) cells, which also expressed vimentin or RECA-1 by dual immunofluorescence labelling. There were few CD34(+)/A3(+) double positive cells. No cells co-expressed A3 and α-smooth muscle actin (a marker of well-differentiated myofibroblastic cells). Although the detailed properties of cells labelled by A3 remain to be discovered, A3 would appear to be a useful marker of immature mesenchymal cells and vascular endothelial cells in developing lungs and in pulmonary fibrosis.

Immunophenotypical analyses of myofibroblasts in rat excisional wound healing: possible transdifferentiation of blood vessel pericytes and perifollicular dermal sheath cells into myofibroblasts.

Cutaneous fibrosis after wound is evoked by myofibroblasts capable of producing collagen; the derivation and features remain to be investigated. Immunophenotypical characteristics of myofibroblasts were analysed in excisional rat wound healing, of which samples were obtained on post-wounding (PW) days 1 to 26. Myofibroblasts were characterized for expressions of intermediate cytoskeletons such as vimentin, desmin, and α-smooth muscle actin (α-SMA). To pursue the progenitor, immunolabeling analyses were performed using stromal-/bone marrow-stem cell markers (Thy-1 and A3). Myofibroblasts reacting to vimentin and α-SMA were first seen on PW day 5, then peaked on PW day 9 in granulation tissues, and gradually decreased in remodeling tissues; these immunopositive cells reacted simultaneously to Thy-1. Desmin-reacting cells were limited to newly-formed blood vessels in wound bed. The single/double immunolabelings revealed that pericytes (identified by positive reaction to PDGFR-ß and negative reaction to endothelial markers) in newly-developing blood vessels reacted to vimentin, α-SMA, Thy-1 and A3, and occasionally to desmin, and that perifollicular dermal sheath cells in the wound periphery showed increased expressions for vimentin, Thy-1 and A3. There is considerable immunophenotypical similarity between myofibroblasts (expressing vimentin, α-SMA and Thy-1), pericytes (reacting to vimentin, α-SMA, Thy-1 and A3) in newly-developing blood vessels, and perifollicular dermal sheath cells (reacting to vimentin, Thy-1 and A3). Collectively, myofibroblasts in rat cutaneous fibrosis are characterized by vimentin, α-SMA and Thy-1 expressions, and the cells might be generated from the pericytes or perifollicular dermal sheath cells in the lineage of stroma-/bone marrow-stem cells.

Heterogeneity of macrophage populations and expression of galectin-3 in cutaneous wound healing in rats.

The aim of this study was to investigate the properties of macrophages that infiltrated the sites of cutaneous wound healing in rats between 1 and 26 days post wounding (dpw). During the inflammation phase (1-3 dpw), ED1(+) (CD68(+)) macrophages with enhanced lysosomal activity dominated. From 5 to 7 dpw there was formation of granulation tissue as indicated by the presence of myofibroblasts expressing α-smooth muscle actin. At this stage, ED2(+) (CD163(+)) macrophages, capable of producing inflammatory factors, were dominant. The majority of ED1(+) macrophages expressed galectin-3, a regulator of fibrosis. Corresponding to the increased numbers of ED1(+) and ED2(+) macrophages at 3-9 dpw, there was increased expression of genes encoding transforming growth factor-ß1 (a major fibrogenic factor), monocyte chemoattractant protein-1 and colony stimulating factor-1. These macrophage-related factors might contribute to inflammation and formation of granulation tissue. OX6(+) macrophages expressing class II molecules of the major histocompatibility complex became predominant in the healing stages (15-26 dpw), indicating important roles for antigen-presenting cells in tissue remodelling. The OX6(+) macrophages were most likely derived from ED1(+) macrophages. The results of this study show that infiltration of phenotypically- and functionally-distinct macrophage populations characterizes different stages of the wound healing process.