Juntao Han

Wnt/β-catenin pathway forms a negative feedback loop during TGF-β1 induced human normal skin fibroblast-to-myofibroblast transition

BACKGROUND Fibroblast-to-myofibroblast transition is a key event during wound healing and hypertrophic scar formation. Previous studies suggested Wnt/β-catenin signaling might be involved in the wound healing. However, its specific role in skin fibroblast-to-myofibroblast transition remains unclear. OBJECTIVE To investigate the specific role of β-catenin during the transforming growth factor-β1 induced normal skin myofibroblasts transition. METHODS By real-time quantitative polymerase chain reaction, Western-blot and immunocytochemistry, the activation of Wnt/β-catenin pathway in cultured human normal skin fibroblasts during TGF-β1 induced fibroblast-to-myofibroblast transition was investigated. The effects of β-catenin on myofibroblasts transition were also investigated when SB-216763, over-expression and siRNA of β-catenin were utilized. In addition, fibroblasts populated collagen lattices contraction assays were conducted to examine the effects of β-catenin on the contractility of the fibroblasts induced by TGF-β1. Furthermore, the effects of β-catenin on the expression of α-smooth muscle actin and collagen types I and III in hypertrophic scar derived fibroblasts were studied. RESULTS The expression of Wnts mRNA and β-catenin protein was up-regulated by TGF-β1 stimulation during the myofibroblasts transition. Both of SB-216763 and β-catenin over-expression was paralleled with decreased expression of α-smooth muscle actin, collagen types I and III, while siRNA targeting β-catenin leads to up-regulation of α-smooth muscle actin, collagen types I and III. The increased contractility and α-smooth muscle actin expression of the fibroblasts in the collagen lattices induced by TGF-β1 was inhibited by SB-216763. In addition, the expression levels of α-smooth muscle actin, collagen types I and III in hypertrophic scar derived fibroblasts were also down-regulated by SB-216763. CONCLUSION Specifically in normal skin fibroblasts, β-catenin might be involved in the myofibroblasts transition and negatively regulate the TGF-β1-induced myofibroblast transition.

The role of ERK and JNK signaling in connective tissue growth factor induced extracellular matrix protein production and scar formation

CCN2 plays an important role in the pathogenesis of hypertrophic scars (HTSs). Although CCN2 is involved in many fibroproliferative events, the CCN2 induction signaling pathway in HTSs is yet to be elucidated. Here, we first investigated the effect of the mitogen-activated protein kinases (MAPKs) on CCN2-induced α-smooth muscle actin (α-SMA) and collagen I expression in human HTS fibroblasts (HTSFs). Then, we established HTSs in a rabbit ear model and determined the effect of MAPKs on the pathogenesis of HTSs. MAPK pathways were activated by CCN2 in HTSFs. Extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK) inhibitors significantly inhibited CCN2-induced expression of α-SMA and collagen I in HTSFs. In the rabbit ear model of the HTS, JNK and ERK inhibitors significantly improved the architecture of the rabbit ear scar and reduced scar formation on the rabbit ear. Our results indicate that ERK and JNK mediate collagen I expression and scarring of the rabbit ear, and may be considered for specific drug therapy targets for HTSs.

Systemic inflammatory responses and multiple organ dysfunction syndrome following skin burn wound and Pseudomonas aeruginosa infection in mice.

ABSTRACT Burn wound–related sepsis is associated with the development of systemic inflammatory response syndrome and multiple organ dysfunction syndrome (MODS). This study is aimed at investigating the development and progression of SIS and MODS in a mouse model of skin burn sepsis. C57BL/6J mice were randomly divided into the sham, burn, Pseudomonas, and burn/Pseudomonas groups. The back skin of the sham, burn, and burn/Pseudomonas groups was burned about 10% of total area with using 37°C or 98°C water for 8 s, respectively, followed by inoculating with Pseudomonas aeruginosa. The Pseudomonas group was infected with P. aeruginosa without burn injury. Their body weights, mortality, organ histology, and function as well as systemic inflammation were measured longitudinally. The burn/Pseudomonas mice lost more body weights than did mice from the other groups and had a significantly higher mortality rate (P < 0.05). The burn/Pseudomonas mice exhibited significantly higher levels of bacterial loads in different organs and serum endotoxin, interleukin 1&bgr;, interleukin 6, tumor necrosis factor &agr;, and C-reactive protein than those in mice from the other groups (P < 0.05). The burn/Pseudomonas mice also displayed more severe liver, lung, and kidney tissue damage and impaired organ functions, particularly at 72 h after inoculation than did the burn and Pseudomonas groups of mice. Our data indicate that burn and P. aeruginosa infection induced severe sepsis and rapidly progressed into systemic inflammatory response syndrome and MODS in mice.

Adipose tissue-derived stem cells suppress hypertrophic scar fibrosis via the p38/MAPK signaling pathway

BackgroundHypertrophic scars (HS) generally occur after injury to the deep layers of the dermis, resulting in functional deficiency for patients. Growing evidence has been identified that the supernatant of adipose tissue-derived stem cells (ADSCs) significantly ameliorates fibrosis of different tissues, but limited attention has been paid to its efficacy on attenuating skin fibrosis. In this study, we explored the effect and possible mechanism of ADSC-conditioned medium (ADSC-CM) on HS.MethodReal-time quantitative polymerase chain reaction (qRT-PCR) and Western blotting were used to detect the expression of collagen I (Col1), collagen III (Col3), and α-smooth muscle actin (α-SMA) after fibroblasts and cultured HS tissues were stimulated with ADSC-CM and p38 inhibitor/activator. Immunofluorescence staining was performed to test the expression of α-SMA. Masson’s trichrome staining, hematoxylin and eosin (H&E) staining, and immunohistochemistry staining were carried out to assess the histological and pathological change of collagen in the BALB/c mouse excisional model. All data were analyzed by using SPSS17.0 software. Statistical analysis was performed by Student’s t tests.ResultsThe in vitro and ex vivo study revealed ADSC-CM decreased the expression of Col1, Col3, and α-SMA. Together, thinner and orderly arranged collagen was manifested in HS tissues cultured with ADSC-CM. Dramatically, the assessed morphology showed an accelerated healing rate, less collagen deposition, and col1- and col3-positive cells in the ADSC-CM treated group. Importantly, the protein level of p-p38 was downregulated in a concentration-dependent manner in HS-derived fibroblasts with ADSC-CM treatment, which further decreased the expression of p-p38 after the application of its inhibitor, SB203580. SB203580 led to an obvious decline in the expression of Col1, Col3, and α-SMA in fibroblasts and cultured HS tissues and presented more ordered arrangement and thinner collagen fibers in BALB/c mice. Lastly, anisomycin, an agonist of p38, upregulated the expression of fibrotic proteins and revealed more disordered structure and denser collagen fibers.ConclusionThis study demonstrated that ADSC-CM could decrease collagen deposition and scar formation in in vitro, ex vivo and in vivo experiments. The regulation of the p38/MAPK signaling pathway played an important role in the process. The application of ADSC-CM may provide a novel therapeutic strategy for HS treatment, and the anti-scarring effect can be achieved by inhibition of the p38/MAPK signaling pathway.

Melatonin prevents acute kidney injury in severely burned rats via the activation of SIRT1

Acute kidney injury (AKI) is a common complication after severe burns. Melatonin has been reported to protect against multiple organ injuries by increasing the expression of SIRT1, a silent information regulator that regulates stress responses, inflammation, cellular senescence and apoptosis. This study aimed to investigate the protective effects of melatonin on renal tissues of burned rats and the role of SIRT1 involving the effects. Rat severely burned model was established, with or without the administration of melatonin and SIRT1 inhibitor. The renal function and histological manifestations were determined to evaluate the severity of kidney injury. The levels of acetylated-p53 (Ac-p53), acetylated-p65 (Ac-p65), NF-κB, acetylated-forkhead box O1 (Ac-FoxO1), Bcl-2 and Bax were analyzed to study the underlying mechanisms. Our results suggested that severe burns could induce acute kidney injury, which could be partially reversed by melatonin. Melatonin attenuated oxidative stress, inflammation and apoptosis accompanied by the increased expression of SIRT1. The protective effects of melatonin were abrogated by the inhibition of SIRT1. In conclusion, we demonstrate that melatonin improves severe burn-induced AKI via the activation of SIRT1 signaling.

Lycium barbarum polysaccharides reduce intestinal ischemia/reperfusion injuries in rats.

Inflammation and oxidative stress exert important roles in intestinal ischemia-reperfusion injury (IRI). Lycium barbarum polysaccharides (LBPs) have shown effective antioxidative and immunomodulatory functions in different models. The purpose of the present study was to assess the effects and potential mechanisms of LBPs in intestinal IRI. Several free radical-generating and lipid peroxidation models were used to assess the antioxidant activities of LBPs in vitro. A common IRI model was used to induce intestinal injury by clamping and unclamping the superior mesenteric artery in rats. Changes in the malondialdehyde (MDA), tumor necrosis factor (TNF)-α, activated nuclear factor (NF)-κB, intracellular adhesion molecule (ICAM)-1, E-selectin, and related antioxidant enzyme levels, polymorphonuclear neutrophil (PMN) accumulation, intestinal permeability, and intestinal histology were examined. We found that LBPs exhibited marked inhibitory action against free radicals and lipid peroxidation in vitro. LBPs increased the levels of antioxidant enzymes and reduced intestinal oxidative injury in animal models of intestinal IRI. In addition, LBPs inhibited PMN accumulation and ICAM-1 expression and ameliorated changes in the TNF-α level, NF-κB activation, intestinal permeability, and histology. Our results indicate that LBPs treatment may protect against IRI-induced intestinal damage, possibly by inhibiting IRI-induced oxidative stress and inflammation.

Inhibition of Notch signaling leads to increased intracellular ROS by up-regulating Nox4 expression in primary HUVECs

The essential roles of Notch pathway in angiogenesis have been reported for years. However, how Notch pathway plays its role in regulating endothelial cells remains largely unknown. In this study we found that blockade of Notch signaling with a γ-secretase inhibitor increased reactive oxygen species (ROS) in primary human umbilical vein endothelial cells (HUVECs) under both normaxic and ischemia/reperfusion (I/R) conditions. Abruption of ROS generation with ROS scavengers or specific inhibitors of ROS production in HUVECs abolished Notch blockade-induced HUVEC proliferation, migration and adhesion, suggesting that the regulation of Notch pathway on endothelial cell behavior is at least partially dependent on its down-regulation of ROS level. We further showed that the enhanced generation of ROS after blocking Notch signal was accompanied by augmented expression of Nox4, which led to increased phosphorylation of VEGFR2 and ERK in HUVECs. In summary, our results have shown that Notch signaling regulates ROS generation by suppressing Nox4, and further modulates endothelial cell proliferation, migration and adhesion.

Effects of Resveratrol on the Treatment of Inflammatory Response Induced by Severe Burn

ABSTRACTThe aim of this study was to preliminarily investigate the effects of resveratrol on the treatment of systemic inflammatory response induced by severe burn wounding. Through the simulation experiment in vivo on burned mice and simulative experiment in vitro on mice macrophage respectively, differences of the related pro-inflammatory cytokines and SIRT1 expression levels between the resveratrol-treated group and the untreated control group were detected and analyzed. The results of the simulation experiment in vivo on burned mice manifested that the survival rate of the mice in the resveratrol-treated group was markedly higher than that of controls (p < 0.05). Resveratrol could significantly reduce the levels of pro-inflammatory factors TNF-α, IL-1β, and IL-6 in serum (p < 0.01) and greatly elevate the expression level of SIRT1 (p < 0.01). The results of the simulative experiment in vitro on mice macrophage showed no significant difference in TNF-α, IL-1β, or IL-6 contents among three groups (C, mice macrophage control group; R, resveratrol-treated macrophage group; I, SIRT1-inhibitor-treated macrophage group). Whereas, after lipopolysaccharide (LPS) activation (L group), macrophage TNF-α, IL-1β, and IL-6 levels were significantly increased in L group, dramatically higher than those in L+R group (LPS and resveratrol treatment group) (p < 0.01). After adding SITR1 inhibitor, three pro-inflammatory cytokines in L+R+I group all showed significant increases compared with those in L+R group (p < 0.01). LPS activated macrophages were able to promote the expression of pro-inflammatory cytokines. By upregulating the expression levels of SIRT1, resveratrol could effectively inhibit the inflammation cascade reaction and increase the survival rate of severe burn with bacterial infections in a large extent.

Effects of integrin ανβ3 on differentiation and collagen synthesis induced by connective tissue growth factor in human hypertrophic scar fibroblasts

CCN2 is a matricellular protein that appears to be important in scar formation. CCN2 mediates the pro-fibrotic effects in hypertrophic scars (HTSs) through an unknown mechanism. However, many activities of CCN2 protein are known to be mediated by direct binding to integrin receptors. In this study, we investigated the role of integrin α(ν)β(3) in the differentiation of hypertrophic scar fibroblasts (HTSFs) induced by CCN2. The levels of integrin α(ν)β(3) between normal skin and hypertrophic scar (HTS) tissues were compared, and integrin α(ν)β(3) was found to be upregulated in HTS. CCN2 was shown to induce HTSF differentiation and collagen (COL) synthesis at the mRNA and protein levels. Based on these results, the expression of integrin α(ν)β(3) was upregulated by CCN2 stimulation during HTSF differentiation. Blockade of integrin α(ν)β(3) prevented CCN2-induced HTSF differentiation and COL synthesis. Furthermore, the CCN2-induced increase in contractility of the HTSF in COL lattices was inhibited by integrin α(ν)β(3) blocking antibodies. HTSs were established in a rabbit ear model, and the inhibitor of integrin α(ν)β(3) significantly improved the architecture of the rabbit ear scar. Results of the present study showed that integrin α(ν)β(3) contributes to pro-fibrotic CCN2 signaling. Blocking this pathway may therefore be beneficial for the treatment of HTS.

Deletion of regulatory T cells supports the development of intestinal ischemia-reperfusion injuries

BACKGROUND Ischemia-reperfusion injury (IRI) of the intestine is associated with high morbidity and mortality in surgical and trauma patients. T cells participate in the pathogenesis of intestinal IRI, and T-cell depletion has been shown to inhibit inflammatory responses and diminish intestinal damage. However, the mechanism by which T cells contribute to intestinal IRI is not completely understood. Regulatory T cells (Tregs) are a specific subset of T cells that suppress immune responses and protect against tissue injuries. We hypothesized that Tregs might be involved in intestinal IRI. MATERIALS AND METHODS We subjected C57/Bl6 mice to 30 min of ischemia by clamping the superior mesenteric artery followed by reperfusion. Animals were pretreated with the anti-CD25 monoclonal antibody or adoptive transfer of Tregs before induction of IRI. The number of inflammatory cells, the level of inflammatory factors, and intestinal permeability were assessed. RESULTS Partial depletion of Tregs with an anti-CD25 monoclonal antibody potentiated intestinal permeability induced by IRI. The Treg-depleted mice showed more neutrophils and CD4(+) T cells. In addition, depletion of Tregs led to enhanced secretion of tumor necrosis factor-α, interferon-gamma, and interleukin (IL)-4 and reduced levels of IL-10. Furthermore, we performed adoptive transfer of Tregs and found that transfer of Tregs significantly inhibited the ischemia-reperfusion-induced increase in intestinal permeability. CONCLUSIONS Our study indicated that Tregs participate in intestinal inflammatory responses induced by IRI and that targeting Tregs could be a novel therapeutic approach to intestinal IRI.