The contribution of bone marrow-derived cells to the development of renal interstitial fibrosis

Recent evidence suggests that bone marrow (BM)-derived cells may integrate into the kidney, giving rise to functional renal cell types, including endothelial and epithelial cells and myofibroblasts. BM-derived cells can contribute to repair of the renal peritubular capillary (PTC) network following acute ischemic injury. However, the cell fate and regulation of BM-derived cells during the progression of chronic renal disease remains unclear. Using chimeric mice transplanted with enhanced green fluorescent protein (EGFP)-expressing BM, we demonstrate that the number of BM-derived myofibroblasts coincided with the development of fibrosis in a mouse adriamycin (ADR)-induced nephrosis model of chronic, progressive renal fibrosis. Four weeks after ADR injection, increased numbers of BM-derived myofibroblasts were observed in the interstitium of ADR-injected mice. Six weeks after ADR injection, more than 30% of renal alpha-smooth muscle actin (+) (alpha-SMA+) interstitial myofibroblasts were derived from the BM. In addition, BM-derived cells were observed to express the endothelial cell marker CD31 and the myofibroblast marker alpha-SMA. Blockade of p38 mitogen-activated protein kinase (MAPK) and transforming growth factor (TGF)-beta1/Smad2 signaling was found to protect BM-derived PTC endothelial cells and inhibit the number of BM-derived von Willebrand factor (vWF)(+)/EGFP(+)/alpha-SMA(+) cells, EGFP(+)/alpha-SMA(+) cells, and total alpha-SMA(+) cells in ADR-injected mice. Inhibition of the p38 MAPK and TGF-beta1/Smad signaling pathways enhanced PTC repair by decreasing endothelial-myofibroblast transformation, leading to structural and functional renal recovery and the attenuation of renal interstitial fibrosis. Investigation of the signaling pathways that regulate the differentiation and survival of BM-derived cells in a progressive disease setting is vital for the successful development of cell-based therapies for renal repair.     

Involvement of p38MAPK/NF-κB Signaling Pathways in Osteoblasts Differentiation in Response to Mechanical Stretch

Bone morphogenetic proteins (BMPs) are known to be important in osteoblasts' response to mechanical stimuli. BMPs/Smad signaling pathway has been demonstrated to play a regulatory role in the mechanical signal transduction in osteoblasts. However, little is currently known about the Smad independent pathway in osteoblasts differentiation in mechanical loading. In this study, MC3T3-E1 cells were subjected to mechanical stretch of 2000?micro-stain (με) at 0.5?Hz, in order to investigate the involvement of p38MAPK and NF-κB signaling pathways in mechanical response in osteoblasts. We found BMP-2/BMP-4 were up-regulated by mechanical stretch via the earlier activation of p38MAPK and NF-κB signaling pathways, which enhanced osteogenic gene expressions including alkaline phosphatase (ALP), collagen type I (Col I) and osteocalcin (OCN), and the expressions of these osteogenic genes were remarkably decreased with Noggin (an inhibitor for BMPs signals) pretreatment. Furthermore, BMP-2/BMP-4 expressions were suppressed by PDTC, an inhibitor of NF-κB pathway and SB203580, an inhibitor of p38MAPK pathway, respectively, leading to the declined levels of ALP, Col I and OCN. Interestingly, blocking in p38MAPK pathway can also cause the inactivation of NF-κB pathway in mechanical stretch. Collectively, the results indicate during mechanical stretch p38MAPK and NF-κB signaling pathways are activated first, and then up-regulate BMP-2/BMP-4 to enhance osteogenic gene expressions. Moreover, p38MAPK and NF-κB signals have cross-talk in regulation of BMP-2/BMP-4 in mechanical response.     

肝星状细胞增殖与p38丝裂原活化蛋白激酶信号传导通路的关系

背景：肝星状细胞的激活、增殖导致肝纤维化,p38丝裂原活化蛋白激酶信号通路可参与调控细胞增殖。 目的：探讨SB203580作用于乙醛刺激的大鼠肝星状细胞后p38丝裂原活化蛋白激酶活性变化和细胞增殖变化。 方法：体外培养大鼠肝星状细胞株,在乙醛干预的基础上加入不同浓度的p38特异性抑制剂SB203580进行培养,并设置对照。以Western blot检测磷酸化p38 蛋白表达水平变化,MTT比色法检测细胞增殖。 结果与结论：乙醛刺激后大鼠肝星状细胞内磷酸化p38水平增强,细胞增殖明显。使用5,10,20 μmol/L SB203580能明显抑制乙醛刺激的肝星状细胞增殖(P < 0.05),加大浓度至30 μmol/L时,抑制作用更明显(P < 0.01),抑制率为43.9%,而磷酸化p38水平也降低(P < 0.05)。结果证实,抑制p38丝裂原活化蛋白激酶活性可能影响肝星状细胞的增殖。     

Differential activation of MAPK signaling pathways by TGF-beta1 forms the molecular mechanism behind its dose-dependent bidirectional effects on hematopoiesis

We have earlier reported that transforming growth factor-beta1 (TGF-beta1), a well-known inhibitor of hematopoiesis, stimulated colony formation from adult human bone marrow mononuclear cells (BM MNC) when used at low concentrations. We examined the possible molecular mechanism behind this bidirectional effect using CD34+ cells isolated from human BM for clonal assays and the KG1a cell line as a model system for analysis of proteins for signaling pathways by immunoblotting. We found that TGF-beta1 at low doses (picogram levels) stimulated the colony formation from CD34+ cells, indicating that these progenitors form the direct target of stimulatory action of TGF-beta1. CD34+ cells were found to be more sensitive to the TGF-beta1 concentration than the total MNC. We used the KG1a cell line as a model system for identification of mitogen-activated protein kinase (MAPK) and AKT signaling pathways involved in the process. Low doses strongly induced p44/42 MAPK phosphorylation, whereas high doses induced p38 activation. Use of specific p44/42 MAPK inhibitor PD 98059 in the colony assay abrogated the stimulatory effect of low TGF-beta1. On the other hand, use of p38 MAPK inhibitor SB 203580 along with low TGF-beta1 concentrations had a synergistic effect on stimulation of colony formation. Treatment of BM MNC with Anisomycin, which activates stress kinases, resulted in a dose-dependent inhibition of colony formation. This inhibition could not be rescued by stimulatory doses of TGF-beta1. Phosphorylation of AKT was found to occur in a dose-dependent way but declined slightly at the highest concentration used (10 ng/ml). Inhibition of the AKT pathway by LY 294002 strongly suppressed colony formation. These data indicate clearly that sustained activation of p44/42 MAPK perhaps forms the stimulatory signal induced by low TGF-beta1, whereas activation of p38 forms the inhibitory pathway.     

p38MAPK参与高糖刺激大鼠肾小管上皮细胞产生细胞外基质胶原Ⅲ

目的：探讨p38MAPK信号通路在高糖刺激大鼠肾小管上皮细胞产生细胞外基质胶原Ⅲ中的作用。 方法： 采用体外培养和Western blotting等方法，以不同浓度D-葡萄糖、p38MAPK信号通路特异性阻断剂SB203580以及用不同时间刺激正常大鼠肾小管上皮细胞NRK52E，分别检NRK52E细胞p38MAPK磷酸化水平和细胞外基质胶原Ⅲ的表达。 结果： 随D-葡萄糖浓度增加，p38MAPK磷酸化水平、胶原Ⅲ的产生也增加，SB203580可有效阻断高糖引起p38MAPK磷酸化水平的升高和细胞外基质胶原Ⅲ的表达的增高。 结论： 高糖引起p38MAPK磷酸化水平的升高可能在糖尿病肾病的肾间质纤维化中发挥重要作用。SB203580有潜在的糖尿病肾病防治的临床应用价值。     

p38 MAPK在顺铂诱导肾小管上皮细胞凋亡中的作用

目的:探讨p38 MAPK在顺铂诱导大鼠近端肾小管上皮细胞(RPTC)凋亡中的作用。方法:首先采用Western blot实验检测0、5、10和20μmol/L顺铂处理24 h对细胞凋亡的影响,确定最佳处理剂量;而后采用20μmol/L顺铂联合50 mg/L p38 MAPK抑制剂SB203580刺激RPTC,实验分为对照组、顺铂组及顺铂+SB203580(加入SB203580处理RPTC 1 h后再给予顺铂处理24 h)。采用相差荧光显微镜观察和流式细胞术分析顺铂处理后RPTC的凋亡情况;采用Ac-DEVD-AFC试剂盒检测RPTC裂解液中的caspase活性;Western blot实验检测p38、磷酸化p38、cleaved PARP和cleaved caspase-3等的蛋白水平;pH计检测顺铂处理后RPTC外环境pH值改变。结果:20μmol/L顺铂处理RPTC 24 h,可以明显诱导细胞凋亡;顺铂处理15 min后RPTC中p38 MAPK开始磷酸化并达到高峰。顺铂处理后12.08%的RPTC呈凋亡形态,具有增强的caspase活性,并且cleaved PARP和cleaved caspase-3水平明显升高(P0.05);p38 MAPK抑制剂SB203580可抑制p38的磷酸化,降低RPTC的凋亡率和caspase活性,并减少cleaved PARP和cleaved caspase-3的蛋白水平。同时,SB203580可逆转顺铂诱导的RPTC培养基pH值的改变。结论:p38 MAPK的磷酸化在顺铂诱导的RPTC凋亡中发挥作用。顺铂诱导RPTC凋亡后,可改变细胞外酸性环境,并可被p38 MAPK抑制剂SB203580所抑制。     

p38 MAPK信号通路参与受体介导的细胞内吞的调控

目的：观察p38 MAPK信号转导通路在受体介导的细胞内吞中的作用。方法：利用Alexa 594标记的转铁蛋白作为受体介导的内吞作用的观察指标，来研究p38特异性抑制剂SB203580或ERK通路特异性抑制剂PD98059预处理以及p38基因敲除对该过程的影响。 结果：在受体介导的细胞内吞中，p38被磷酸化激活。SB203580的预处理或p38基因的敲除都能阻断受体介导的细胞内吞，而PD98059的预处理对该过程没有影响。 结论：p38 MAPK信号转导通路参与了受体介导的细胞内吞的调控。     

p38 Mitogen-Activated Protein Kinase Inhibition Decreases TNFalpha Secretion and Protects Against Left Ventricular Remodeling in Rats with Myocardial Ischemia

The purpose of this study was to test our hypothesis that p38 mitogen-activated protein kinase (p38 MAPK) inhibitor SB203580 may favorably affect tumor necrosis factor alpha (TNFα) secretion and left ventricular (LV) remodeling after myocardial ischemia (MI). The left anterior descending coronary artery (LAD) was ligated to produce anterior MI in 40 rats that were randomly divided into two groups: p38i group (n = 24) and MIR group (MI rat models, n = 24). A sham operation group without LAD ligation (Sham, n = 16) was also studied. SB203580 (2 mg/kg) and saline was injected i.p. once every 3 days in the first two groups, respectively. One and six weeks after MI, cardiac function, myocardial fibrosis, the cardiac expressions of phosphorylated p38 MAPK (p-p38 MAPK), TNFα, alpha smooth muscle actin (αSMA) and collagen I, the ultramicrostructure of the myocardium were examined by echocardiography, histological staining, western blot, immunohistochemical staining, transmission electron microscope (TEM), respectively. Treatments with SB203580 suppressed myocardial fibrosis and LV remodeling, as well as attenuated the expressions of p-p38-MAPK, TNFα, αSMA and collagen I as compared with the MIR. In conclusion, SB203850 has an effect of inhibiting inflammation-induced fibrosis, which leads to attenuation of LV remodeling.     

BML-111 Attenuates Renal Ischemia/Reperfusion Injury Via Peroxisome Proliferator-Activated Receptor-α-Regulated Heme Oxygenase-1

We examine whether BML-111, a lipoxin receptor agonist, inhibits renal ischemia/reperfusion (I/R) injury, and whether peroxisome proliferator-activated receptor-α (PPARα) or heme oxygenase-1 (HO-1) is involved in protective effects of BML-111 on kidney against I/R injury. Rats subjected to renal I/R injury were treated with or without BML-111. Renal histological and immunohistochemical studies were performed. Expressions of phosphorylated p38 mitogen-activated protein kinase (pp38 MAPK), phosphorylated PPARα (pPPARα), and HO-1 were assessed in NRK-52E cells exposed to BML-111. The binding activity of PPARα to peroxisome proliferator-responsive element (PPRE) on HO-1 promoter in the cells was determined. BML-111 treatment resulted in a marked reduction in the severity of histological features of renal I/R injury, and attenuated the rise in renal myeloperoxidase and malondialdehyde, blood urea nitrogen and creatinine, urinary N-acetyl-β-glucosaminidase, and leucine aminopeptidase levels caused by I/R injury. BML-111 stimulated the renal expressions of pPPARα and HO-1, and cellular messenger RNA (mRNA) and protein expressions of pPPARα and HO-1 which were both blocked by GW6471, a selective PPARα antagonist, and ZnPP-IX, a specific inhibitor of HO-1 pretreatment. The pp38 MAPK inhibitor SB203580 blocked the BML-111-induced expressions of pp38 MAPK, pPPARα, and HO-1 in NRK-52E cells. The binding activity of PPARα to PPRE in nuclear extracts of NRK-52E cells was enhanced by treatment of the cells with BML-111, and was suppressed by GW6471 and SB203580. BML-111 protects the kidney against I/R injury via activation of p38 MAPK/PPARα/HO-1 pathway.     

Tumor Necrosis Factor-Like Weak Inducer of Apoptosis (TWEAK) Mediates p38 Mitogen-Activated Protein Kinase Activation and Signal Transduction in Peripheral Blood Mononuclear Cells from Patients with Lupus Nephritis

Forty-two patients with systemic lupus erythematosus (SLE), including 26 patients with renal damage and 16 without, and 20 healthy controls were included in the study. The isolated peripheral blood mononuclear cells (PBMCs) were treated with a p38 inhibitor (SB203580) or anti-tumor necrosis factor-like weak inducer of apoptosis (TWEAK) mAb, with or without phytohemagglutinin/phorbol myristate acetate (PHA/PMA) stimulation. Western blot experiments were used to evaluate the protein expression of TWEAK and p38 MAPK in PBMCs .Next, the contents of interleukin-10 (IL-10) and monocyte chemoattractant protein-1 (MCP-1) in the supernatant were measured by ELISA. The results showed that expression of TWEAK protein in PBMCs from lupus nephritis patients was significantly higher than that from SLE patients without renal damage and healthy controls. PHA/PMA simulation could upregulate the productions of TWEAK and p-p38MAPK in PBMCs from patients with SLE. Anti-TWEAK mAb treatment downregulated both TWEAK and p-p38 MAPK expression in PBMCs, as well as IL-10 and MCP-1 in the supernatant; SB203580 had the same effect on cytokine production in PBMC, but had no effect on the expression of TWEAK. Our results suggested that TWEAK–p38 MAPK–IL-10, MCP-1 signaling pathway in PBMC played an important pathogenic role in lupus nephritis.     

周期性张应力诱导成纤维细胞凋亡中p38MAPK信号通路的作用

背景：当牙齿受异常咬合力时会导致牙体吸收、牙周组织的大量破坏。 目的：研究牙周膜成纤维细胞在受到周期性张应力刺激后是否发生凋亡及p38MAPK信号通路是否参与该凋亡过程。 方法：取4~7代成纤维细胞,同步化后随机分为对照组、加力组和SB203580组。加力组和SB203580组细胞加载力值为12%表面应变率,加力频率为6个循环/min,即5 s拉伸,5 s松弛。SB203580组细胞在加力前1 h加入终浓度为20 mmol/L的p38MAPK抑制剂SB203580。分别在加力6,12,24 h,取各组细胞,流式细胞仪检测细胞凋亡,RT-PCR检测细胞凋亡基因bax mRNA的表达。 结果与结论：与对照组比较,加力后成纤维细胞凋亡率及bax mRNA表达增加 (P < 0.05),且随着加力时间的延长而增强,12 h达高峰,之后逐渐下降。与加力组比较,SB203580组对应时间点细胞凋亡减少 (P < 0.05),bax mRNA表达降低。说明细胞受到力学刺激会发生凋亡,而丝裂原活化蛋白激酶p38MAPK信号通路参与了该凋亡过程。     

辛伐他汀通过抑制p38 MAPK活化降低肝硬化门静脉高压大鼠门静脉压力

 目的:探讨p38 MAPK信号通路在辛伐他汀降低肝硬化门静脉高压症大鼠门静脉压力（PP）中的作用。方法:采用四氯化碳复合因素法构建大鼠肝硬化门静脉高压症模型,成模后将存活大鼠随机分为模型组（n=10）、辛伐他汀治疗组（n=11）和p38 MAPK信号通路抑制剂SB203580处理组（n=10）,后2组分别给予辛伐他汀及SB203580干预处理;另设正常对照组（n=8）。处理结束后检测大鼠PP、肝脏总p38 MAPK蛋白、磷酸化p38 MAPK蛋白、总eNOS蛋白、磷酸化eNOS蛋白表达水平以及肝脏一氧化氮（NO）含量的变化。结果:（1）模型组大鼠PP明显高于正常对照组;辛伐他汀治疗组及SB203580处理组PP均明显低于模型组（P＜0.01）,辛伐他汀治疗组PP明显低于SB203580处理组（P＜0.01）。（2）与正常大鼠相比,模型组大鼠肝脏总p38 MAPK蛋白及总eNOS蛋白表达水平无明显变化（P＞0.05）,而磷酸化p38 MAPK蛋白及磷酸化eNOS蛋白表达水平分别增高与降低（P＜0.01）;辛伐他汀治疗组大鼠肝脏磷酸化p38 MAPK蛋白及磷酸化eNOS蛋白表达水平分别降低与增高（P＜0.01）;SB203580处理组大鼠肝脏磷酸化p38 MAPK蛋白及磷酸化eNOS蛋白表达水平分别降低与增高（P＜0.01）,但磷酸化eNOS蛋白表达水平增高的程度低于辛伐他汀治疗组（P＜0.01）。(3)辛伐他汀治疗组肝脏NO含量［（15.73±1.59） μmol/(g protein)］及SB203580处理组肝脏NO含量［（13.98±1.27) μmol/(g protein)］明显高于模型组［（9.81±1.12） μmol/（g protein）］（P＜0.01）,辛伐他汀治疗组NO含量明显高于SB203580处理组（P＜0.01）。结论: 辛伐他汀降低肝硬化门静脉高压症大鼠门静脉压力可能与其抑制p38 MAPK信号通路的活化有关。     

An inhibitor of stress-activated MAP-kinases reduces invasion and MMP-2 expression of malignant melanoma cells

A lot of parallels have been described between invasion of malignant tumor cells and leukocyte movement during inflammatory responses. Concerning these similarities, we investigated the function of cytokine-suppressive anti-inflammatory drugs (CSAIDs), which act via inhibition of stress-activated MAP-kinases, in regulation of expression of proteolytic enzymes and in vitro invasion of malignant melanoma cells. The p38MAPK inhibitor SB203580 reduced matrigel invasion of MeWo cells by 60%, while the MEK-1 inhibitor PD98059 did not have any effect on invasion. Active p38MAPK was detected in MeWo cells by immunoblotting and confocal microscopy. Cells showed a constitutive expression of matrix-metalloproteinase (MMP)-2 as well as tissue inhibitor of metalloproteinases (TIMP)-1 and TIMP-2 mRNAs. Expression of MMP-1 or urokinase-type plasminogen activator (uPA) was not detected by Northern blot. Inhibition of p38MAPK by the specific inhibitor SB203580 resulted in downregulation of MMP-2 mRNA and protein levels as well as gelatinolytic activity, while expression levels of TIMP-1 and TIMP-2 mRNAs were not changed. The specific MEK-1 inhibitor PD98059 did not change expression of MMP-2 or TIMPs. Neither SB203580 nor PD98059 changed proliferation of cells. The results suggest that stress-activated protein kinases like p38MAPK are involved in regulation of expression of MMP-2 as well as in vitro invasion of malignant melanoma cells. Inhibitors of p38MAPK may be promising substances to interfere with a signaling cascade associated with invasion of malignant tumor cells.     

Inhibition of activin receptor-like kinase 5 attenuates bleomycin-induced pulmonary fibrosis

Activin receptor-like kinase 5 (ALK5) is a type I receptor of transforming growth factor (TGF)-beta. ALK5 inhibition has been reported to attenuate the tissue fibrosis including pulmonary fibrosis, renal fibrosis and liver fibrosis. To elucidate the inhibitory mechanism of ALK5 inhibitor on pulmonary fibrosis in vivo, we performed the histopathological assessment, gene expression analysis of extracellular matrix (ECM) genes and immunohistochemistry including receptor-activated Smads (R-Smads; Smad2/3), CTGF, myofibroblast marker (alpha-smooth muscle actin; aSMA) and type I collagen deposition in the lung using Bleomycin (BLM)-induced pulmonary fibrosis model. ALK5 inhibitor, SB-525334 (10 mg/kg or 30 mg/kg) was orally administered at twice a day. Lungs were isolated 5, 7, 9 and 14 days after BLM treatment. BLM treatment led to significant pulmonary fibrotic changes accompanied by significant upregulation of ECM mRNA expressions, Smad2/3 nuclear translocation, CTGF expression, myofibroblast proliferation and type I collagen deposition. SB-525334 treatment attenuated the histopathological alterations in the lung, and significantly decreased the type I and III procollagen and fibronectin mRNA expression. Immunohistochemistry revealed that SB-525334 treatment showed significant attenuation in Smad2/3 nuclear translocation, decrease in CTGF-expressing cells, myofibroblast proliferation and type I collagen deposition. These results suggest that ALK5 inhibition attenuates R-Smads activation thereby attenuates pulmonary fibrosis.     

Inhibition of p38 Mitogen-Activated Protein Kinase Down-regulates the Inflammatory Osteolysis Response to Titanium Particles in a Murine Osteolysis Model

The p38 mitogen-activated protein kinase (p38 MAPK) pathway is involved in the osteoclast differentiation. The aim of the study was to investigate whether SB203580, a p38 MAPK inhibitor, inhibits wear-debris-induced inflammatory osteolysis in mice. Forty-five mice were implanted with calvaria bone from syngeneic littermates; then, titanium (Ti) particles were injected into established air pouches to provoke inflammatory osteolysis. At 14?days after bone/Ti implantation, pouch membranes with intact bone implants underwent histological and molecular analysis. SB203580 had less effect on MMP-9 and TNF-?? expression under wear-debris-induced conditions. SB203580, by inhibiting the expression of p38 MAPK and phospho-p38 MAPK, inhibited Ti particle wear-debris-induced inflammatory osteolysis. It also remarkably decreased the number of tartrate-resistant acid phosphatase positive cells in Ti-particle-induced pouch tissues. Results suggest that p38 MAPK may be critical in a murine osteolysis model. SB203580 may notably inhibit wear-debris-induced inflammatory osteolysis by down-regulating expression of MMP-9 and TNF-?? via the p38 MAPK pathway.