CCK—8 inhibits expression of TNF—α in the spleen of endotoxic shock rate and sigual transduction mechanism of p38 MAPK

AIM: To study the effect of sulfated cholecystokinin-octapeptide (CCK-8) on systemic hypotension, gene and protein expression of TNF-alpha in the spleen of lipopolysaccharide (LPS)-induced endotoxic shock (ES) rats, and further investigate the signal transduction mechanism of p38 mitogen-activated protein kinase (MAPK). METHODS: The changes of blood pressure were observed using physiological record instrument in the four groups of rats: LPS (8 mg x kg(-1), iv), CCK-8 (40 microg x kg(-1), iv) pretreatment 10 min before LPS (8 mg x kg(-1)), CCK-8 (40 microg x kg(-1), iv) or normal saline (control) group. The content of TNF-alpha in the spleen was assayed 2 h after LPS administration using ELISA kit and the expression of TNF-alpha mRNA was examined 30 min, 2 h and 6 h after LPS administration by reverse transcribed polymerase chain reaction (RT-PCR). Activation of p38 MAPK was detected with Western blot 30 min after LPS administration. RESULTS: CCK-8 reversed LPS-induced decrease of mean arterial pressure (MAP) in rats. The content of TNF-alpha in the spleen was (282+/-30) ng x L(-1) in control group, while it increased to (941+/-149) ng x L(-1) in LPS group, P<0.01. CCK-8 significantly inhibited the LPS-induced increase of TNF-alpha content in spleen. It decreased to (462 +/-87) ng x L(-1) in CCK-8+LPS group, P<0.01. The expression of TNF-alpha mRNA 30 min and 2 h after treatment was stronger in LPS group, while it was lowered after CCK-8 pretreatment. The p38 MAPK expression increased significantly in LPS group (5.84 times of control) and CCK-8 increased the activation of p38 MAPK in ES rats (10.74 times of control). CONCLUSION: CCK-8 reverses the decrease of MAP in ES rats and has inhibitory effect on the gene and protein expression of TNF-alpha in spleen, and p38 MAPK may be involved in its signal transduction mechanisms.     

Rho proteins and the p38-MAPK pathway are important mediators for LPS-induced interleukin-8 expression in human endothelial cells

Bacterial endotoxin (lipopolysaccharide, or LPS) has potent proinflammatory properties by acting on many cell types, including endothelial cells. Secretion of the CXC-chemokine interleukin-8 (IL-8) by LPS-activated endothelial cells contributes substantially to the inflammatory response. Using human umbilical vein endothelial cells (HUVECs), we analyzed the role of small GTP-binding Rho proteins and p38 mitogen-activated protein kinase (MAPK) for LPS-dependent IL-8 expression in endothelial cells. Specific inactivation of RhoA/Cdc42/Rac1 by Clostridium difficile toxin B-10463 (TcdB-10463) reduced LPS-induced tyrosine phosphorylation, nuclear factor (NF)-kappaB-dependent gene expression, IL-8 messenger RNA, and IL-8 protein accumulation but showed no effect on LPS-dependent p38 MAPK activation. Inhibition of p38 MAPK by SB 202190 also blocked LPS-induced NF-kappaB activation and IL-8 synthesis. Furthermore, selective activation of the p38 MAPK pathway by transient expression of a constitutively active form of MAPK kinase (MKK)6, the upstream activator of p38, was as effective as LPS with respect to IL-8 expression in HUVECs. In summary, our data suggest that LPS-induced NF-kappaB activation and IL-8 synthesis in HUVECs are regulated by both a Rho-dependent signaling pathway and the MKK6/p38 kinase cascade.     

Rac1 mediates sex difference in cardiac tumor necrosis factor-α expression via NADPH oxidase-ERK1/2/p38 MAPK pathway in endotoxemia

The purpose of this study was to investigate the role of Rac1 and estrogen in sex difference of cardiac tumor necrosis factor-alpha (TNF-α) expression during endotoxemia. Endotoxemia was induced in male and female mice by peritoneal injection of lipopolysaccharide (LPS, 4 mg/kg). Compared with female mice, male mice produced more TNF-α in the heart 4 h after LPS treatment, which were correlated with higher Rac1 and NADPH oxidase activity, more phosphorylation of ERK1/2 and p38 MAPK, and up-regulation of toll-like receptor-4 (TLR-4) expression in male mice. Cardiac specific Rac1 knockout or administration of 17β-estradiol down-regulated Rac1 expression, attenuated gp91^phox-NADPH oxidase expression and activity, decreased phosphorylation of ERK1/2/p38 MAPK and inhibited cardiac TNF-α expression induced by LPS, suggesting an important role of Rac1 and estrogen in LPS-stimulated TNF-α expression in the heart. More importantly, the sex difference in TNF-α expression was abrogated by Rac1 knockout or gp91^phox knockout and by administration of apocynin or N-acetylcysteine in LPS-stimulated mice. To investigate the functional significance of sex difference in endotoxemia, heart function was measured in isolated hearts with a Langendorff system. Male mice exhibited worse myocardial dysfunction compared with female in endotoxemia. Treatment of male mice with 17β-estradiol attenuated myocardial dysfunction during endotoxemia. In conclusion, LPS induces Rac1 activation, which contributes to NADPH oxidase activity and phosphorylation of ERK1/2/p38 MAPK, leading to TNF-α expression in the heart. The sex difference in TNF-α expression is estrogen-dependent and mediated via Rac1 dependent NADPH oxidase/ERK1/2 and p38 MAPK pathway in LPS-stimulated hearts.     

Cytochrome P4502E1 sensitizes to tumor necrosis factor alpha-induced liver injury through activation of mitogen-activated protein kinases in mice

The goal of this study was to evaluate the role of mitogen-activated protein kinase (MAPK) in cytochrome P4502E1 (CYP2E1) potentiation of lipopolysaccharide or tumor necrosis factor alpha (TNF-alpha)-induced liver injury. Treatment of C57/BL/6 mice with pyrazole (PY) plus lipopolysaccharide (LPS) induced liver injury compared with mice treated with PY or LPS alone. The c-Jun N-terminal kinase (JNK) inhibitor SP600125 or p38 MAPK inhibitor SB203580 prevented this liver injury. PY plus LPS treatment activated p38 MAPK and JNK but not extracellular signal-regulated kinase (ERK). PY plus LPS treatment triggered oxidative stress in the liver with increases in lipid peroxidation, decrease of glutathione (GSH) levels, and increased production of 3-nitrotyrosine adducts and protein carbonyl formation. This oxidative stress was blocked by SP600125 or SB203580. PY plus LPS treatment elevated TNF-alpha production, and this was blocked by SP600125 or SB203580. Neither SP600125 nor SB203580 affected CYP2E1 activity or protein levels. Treating C57/BL/6 mice with PY plus TNF-alpha also induced liver injury and increased lipid peroxidation and decreased GSH levels. Prolonged activation of JNK and p38 MAPK was observed. All of these effects were blocked by SP600125 or SB203580. In contrast to wild-type SV 129 mice, treating CYP2E1 knockout mice with PY plus TNF-alpha did not induce liver injury, thus validating the role of CYP21E1 in this potentiated liver injury. Liver mitochondria from PY plus LPS or PY plus TNF-alpha treated mice underwent calcium-dependent, cyclosporine A-sensitive swelling, which was prevented by SB203580 or SP600125. CONCLUSION: These results show that CYP2E1 sensitizes liver hepatocytes to LPS or TNF-alpha and that the CYP2E1-enhanced LPS or TNF-alpha injury, oxidant stress, and mitochondrial injury is JNK or p38 MAPK dependent.     

Phospholipase Cgamma1 signalling regulates lipopolysaccharide-induced cyclooxygenase-2 expression in cardiomyocytes

Lipopolysaccharide (LPS) induces cyclooxygenase-2 (COX-2) expression in cardiomyocytes, which plays a role in myocardial depression during endotoxemia. The purpose of this study was to investigate the role of phosphatidylinositol (PI)-phospholipase Cgamma1 (PLCgamma1) in cardiac COX-2 expression in vitro and in vivo. In cultured mouse neonatal cardiomyocytes, LPS increased PLCgamma1 phosphorylation and COX-2 expression. Knockdown of PLCgamma1 with specific siRNA or inhibition of PI-PLC with U73122 attenuated COX-2 mRNA and protein expression induced by LPS (1 microg/ml). PLCgamma1 activation by LPS also increased ERK1/2 MAPK phosphorylation, and inhibition of ERK1/2 MAPK blocked the effect of PLCgamma1 on COX-2 expression. Furthermore, activation of PLCgamma1 is a consequence of the Src family activation since inhibition of Src abrogated whereas over-expression of Src enhanced PLCgamma1 phosphorylation and COX-2 expression in LPS-stimulated cardiomyocytes. To investigate the role of PLCgamma1 in endotoxemia, wild-type and PLCgamma1(+/-) adult mice were pre-treated with U73122, or its inactive analog, U73343 (9 mg/kg, i.p.), or vehicle for 15 min followed by LPS (4 mg/kg, i.p.) for 4 h. U73122 or heterozygous deletion of PLCgamma1 decreased cardiac COX-2 expression. The phosphorylation of ERK1/2 MAPK induced by LPS was also attenuated in U73122- or PLCgamma1(+/-) compared to U73343-treated or wild-type littermate hearts, respectively. In conclusion, our study suggests that PLCgamma1 signalling represents a novel pathway regulating cardiac COX-2 expression during LPS stimulation. The Src family is responsible for PLCgamma1 activation, which signals the ERK1/2 MAPK pathway, resulting in COX-2 production in LPS-stimulated cardiomyocytes.     

血管紧张素Ⅱ对人脐静脉内皮细胞p38丝裂素激活蛋白激酶通路的作用

目的探讨血管紧张素Ⅱ(AngⅡ)激活人脐静脉内皮细胞(HUVECs)p38丝裂素激活蛋白激酶(p38MAPK)信号转导通路的作用。方法用含20%胎牛血清的DMEM培养基与CO_2培养箱(5%CO_2+95%空气)培养HUVECs。待细胞生长至80%融合时,无血清培养16h后分组:(1)AngⅡ不同时点观察组:用AngⅡ(终浓度100 nmol/L)分别刺激细胞0、5、10、15、30、45 min和60 min。(2)AngⅡ不同剂量作用组:分别用终浓度为0、10、100、1000 nmol/L和10 000 nmol/L的AngⅡ刺激细胞15 min。(3)AngⅡ+p38MAPK特异性抑制剂SB202190组:在AngⅡ(终浓度100 nmol/L)刺激前30 min,分别将1000 nmol/L和5000 nmol/L(终浓度)的SB202190加入培养基,共同孵育30 min。上述各组作用一定时间后收集细胞,用Western blot方法测定细胞p38MAPK磷酸化表达。结果 AngⅡ(100 nmol/L)可诱导HUVECs p38MAPK磷酸化表达,15～30 min达到高峰,分别升高2.25和2.51倍(P<0.005,n=5),随时间呈峰形变化;AngⅡ呈剂量依赖性诱导HUVECs p38MAPK磷酸化,在AngⅡ100 nmol/L时p38MAPK磷酸化表达即有明显增强,在AngⅡ刺激剂量为1000 nmol/L和10 000 nmol/L时,p38MAPK磷酸化表达分别增加2.03和2.11倍(P<0.005,n=5);p38MAPK特异性抑制剂SB202190可显著抑制HUVECs p38MAPK磷酸化,且呈剂量依赖性,5000 nmol/L SB202190的抑制率为53.9%(P<0.01,n=6)。结论 AngⅡ可激活人脐静脉内皮细胞p38MAPK信号通路。     

Opposing effect of p38 MAP kinase and JNK inhibitors on the development of heart failure in the cardiomyopathic hamster

OBJECTIVE: p38 MAP kinase (p38 MAPK) and c-Jun NH2-terminal kinase (JNK) have been implicated in the pathophysiology of heart failure. We investigated the effects of chronic treatment with p38 MAPK and JNK inhibitors on the development of heart failure in dilated cardiomyopathy (DCM) hamster heart. METHODS AND RESULTS: BIO14.6 hamster hearts showed markedly increased p38 MAPK and JNK activities at 6 weeks of age when there was no significant increase in the area of fibrosis, heart weight/body weight, left ventricular (LV) chamber dilation and LV dysfunction. p38 MAPK and JNK activities were attenuated at 26 weeks of age and abolished at 40 weeks of age in BIO14.6 hamster hearts. BIO14.6 hamsters and the control BIOF1B hamsters were chronically treated (i.p.) with the p38 MAPK inhibitors, SB203580 (1 mg/kg/day) and FR167653 (3 mg/kg/day), or the JNK inhibitor, SP600125 (1 mg/kg/day) or vehicle for 20 weeks starting from 6 weeks of age. Treatment of BIO14.6 hamster hearts with SB203580 and FR167653 reduced the number of TUNEL-positive myocytes, the area of fibrosis and heart weight/body weight associated with a significant decrease of LV dimension and an increase in LV ejection fraction and LV contractility compared to the vehicle-treated counterpart. In contrast, treatment with SP600125 increased the number of TUNEL-positive myocytes and the area of interstitial fibrosis associated with aggravation of LV chamber dilation and LV dysfunction. CONCLUSIONS: These results suggest that chronic treatment with p38 MAPK and JNK inhibitors produces opposing effects on the development of heart failure in the DCM hamster heart.     

p38MAPK inhibition enhances basal and norepinephrine-stimulated p42/44MAPK phosphorylation in rat pinealocytes

Interaction between p38MAPK and p42/44MAPK in rat pinealocytes was examined by determining the effects of p38MAPK inhibitors on the phosphorylation of p42/44MAPK using Western blot analysis. Treatment with SB202190, a specific inhibitor of p38MAPK, increased p42/44MAPK phosphorylation in a concentration-dependent manner. SB202190 also enhanced the magnitude and the duration of norepinephrine-activated p42/44MAPK phosphorylation. The effect of SB202190 on p42/44MAPK phosphorylation was abolished by PD98059 or UO126, inhibitors of MEK, suggesting that SB202190 is acting upstream of MEK in activating p42/44MAPK. The SB202190-induced phosphorylation of p42/44MAPK was not blocked by inhibitors of cGMP-dependent kinase (KT5823), protein kinase C (calphostin C) or Ca2+/calmodulin dependent kinase (KN93) suggesting that these pathways may not be involved in the effect of SB202190. SB202190 further increased p42/44MAPK phosphorylation that was stimulated by 8-bromo-cGMP, 4beta phorbol 12-myristate 13-acetate, or ionomycin. In contrast, inhibition of p42/44MAPK phosphorylation by dibutyryl-cAMP persisted when p42/44MAPK phosphorylation was increased by SB202190. Furthermore, inhibition of p42/44MAPK phosphorylation had no effect on p38MAPK activation. These results suggest that inhibition of p38MAPK causes activation of p42/44MAPK and acts synergistically with norepinephrine in the regulation of p42/44MAPK activation in rat pinealocytes.     

Increased collagen deposition and diastolic dysfunction but preserved myocardial hypertrophy after pressure overload in mice lacking PKCepsilon

Overexpression and activation of protein kinase C-epsilon (PKCepsilon) results in myocardial hypertrophy. However, these observations do not establish that PKCepsilon is required for the development of myocardial hypertrophy. Thus, we subjected PKCepsilon-knockout (KO) mice to a hypertrophic stimulus by transverse aortic constriction (TAC). KO mice show normal cardiac morphology and function. TAC caused similar cardiac hypertrophy in KO and wild-type (WT) mice. However, KO mice developed more interstitial fibrosis and showed enhanced expression of collagen Ialpha1 and collagen III after TAC associated with diastolic dysfunction, as assessed by tissue Doppler echocardiography (Ea/Aa after TAC: WT 2.1+/-0.3 versus KO 1.0+/-0.2; P<0.05). To explore underlying mechanisms, we analyzed the left ventricular (LV) expression pattern of additional PKC isoforms (ie, PKCalpha, PKCbeta, and PKCdelta). After TAC, expression and activation of PKCdelta protein was increased in KO LVs. Moreover, KO LVs displayed enhanced activation of p38 mitogen-activated protein kinase (MAPK) and c-Jun N-terminal kinase (JNK), whereas p42/p44-MAPK activation was attenuated. Under stretch, cultured KO fibroblasts showed a 2-fold increased collagen Ialpha1 (col Ialpha1) expression, which was prevented by PKCdelta inhibitor rottlerin or by p38 MAPK inhibitor SB 203580. In conclusion, PKCepsilon is not required for the development of a pressure overload-induced myocardial hypertrophy. Lack of PKCepsilon results in upregulation of PKCdelta and promotes activation of p38 MAPK and JNK, which appears to compensate for cardiac hypertrophy, but in turn, is associated with increased collagen deposition and impaired diastolic function.     

Role of neuronal nitric oxide synthase in lipopolysaccharide-induced tumor necrosis factor-alpha expression in neonatal mouse cardiomyocytes

OBJECTIVE: Neuronal nitric oxide synthase (nNOS) has been shown to regulate intracellular calcium in cardiomyocytes. Calcium in turn modulates extracellular signal-related kinase (ERK) signaling, which is important in tumor necrosis factor-alpha (TNF-alpha) expression during lipopolysaccharide (LPS) stimulation. However, the role of nNOS in LPS-induced TNF-alpha expression is not known. We hypothesized that nNOS suppresses LPS-induced TNF-alpha expression by inhibiting the calcium/ERK signaling pathway. METHODS AND RESULTS: Cultured neonatal mouse cardiomyocytes were challenged with LPS for 4 h. While there was no change in the basal Ca(2+) concentration, LPS increased peak Ca(2+) levels. LPS stimulation increased TNF-alpha mRNA and protein levels in wild-type cells however, the responses were enhanced in nNOS(-/-) cardiomyocytes. Treatment with an antisense oligonucleotide against nNOS also significantly enhanced TNF-alpha expression during LPS stimulation. Furthermore, LPS-induced ERK phosphorylation was significantly increased in the nNOS(-/-) compared to wild-type cardiomyocytes. The enhanced TNF-alpha expression in nNOS(-/-) cardiomyocytes was abrogated by an L-type calcium channel blocker verapamil or ERK1 siRNA. Finally, myocardial ERK phosphorylation and TNF-alpha expression were increased while cardiac function was decreased in endotoxemia in nNOS(-/-) compared to wild-type mice. CONCLUSIONS: nNOS inhibits LPS-induced TNF-alpha expression in cardiomyocytes and improves cardiac function in endotoxemia. The inhibitory role of nNOS is mediated by a reduction in L-type calcium channel-dependent ERK signaling in cardiomyocytes.     

辛伐他汀抑制人外周血单核巨噬细胞脂蛋白相关磷脂酶A2表达

目的 观察辛伐他汀对人外周血单核巨噬细胞脂蛋白相关磷脂酶A2(Lp-PLA2)表达的影响,并探讨其调控机制.方法 分离培养人外周血单核巨噬细胞,实验分为脂多糖(LPS)组、辛伐他汀组和丝裂原活化蛋白激酶(MAPK)干预组.LPS组:分别用不同浓度(0、1、10、102、103和104ng/ml)的LPS与细胞共同孵育6 h,观察不同浓度的辛伐他汀对LPS诱导的Lp-PLA2 mRNA和蛋白表达的影响;并用1μg/ml的LPS与细胞孵育不同时间(0、6、12、24和48 h),观察辛伐他汀作用不同时间对LPS诱导的Lp-PLA2 mRNA和蛋白表达的影响.辛伐他汀组:1 μg/ml的LPS+不同浓度的辛伐他汀(10-2～10-7mmol/L)与单核巨噬细胞共同孵育24 h,1 μg/ml LPS+10-3mmol/L的辛伐他汀与单核巨噬细胞孵育不同时间(0、6、24、24和48 h),观察辛伐他汀对LPS诱导的Lp-PLA2mRNA和蛋白表达及酶活性的影响.MAPK组:分别用10 μmol/L的p38抑制剂SB203580、20 μmol/L的ERK抑制剂U0126和20 μmol/L的JNK抑制剂SP600125预处理30 min后,将单核巨噬细胞与1μg/ml的LPS共同孵育24 h,观察MAPK信号通路在LPS介导的Lp-PLA2表达中的作用.逆转录-多聚酶链反应(RT-PCR)方法 检测Lp-PLA2 mRNA表达,比色法测定酶活性,Western blot方法 检测Lp-PLA2蛋白表达以及p38-MAPK蛋白及磷酸化水平.结果 (1)0.1μg/ml的LPS刺激6 h即可显著增加单核巨噬细胞Lp-PLA2 mRNA和蛋白的表达及其酶活性,并且随LPS浓度的增加和刺激时间的延长,该作用增强.(2)辛伐他汀可以明显抑制LPS诱导的Lp-PLA2的表达增加,并且降低酶活性,该作用呈浓度及时间依赖性.(3)辛伐他汀抑制LPS诱导的p38MAPK蛋白活化,p38MAPK的抑制剂SB203580可以完全阻断LPS介导的Lp-PLA2蛋白表达增加,与辛伐他汀作用相似.而MEK1/2的抑制剂U0126和JNK的抑制剂SP600125对LPS介导的Lp-PLA2蛋白表达的增加没有影响.结论 在培养的人外周血单核巨噬细胞中,辛伐他汀可以明显抑制LPS诱导的Lp-PLA2 mRNA和蛋白表达,降低Lp-PLA2酶活性,该作用至少部分由抑制p38MAPK信号转导通路介导.     

Inhibition of Na/K-ATPase promotes myocardial tumor necrosis factor-alpha protein expression and cardiac dysfunction via calcium/mTOR signaling in endotoxemia

Tumor necrosis factor-α (TNF-α) is a major pro-inflammatory cytokine that causes cardiac dysfunction during sepsis. Na/K-ATPase regulates intracellular Ca²⁺, which activates mammalian target of rapamycin (mTOR), a regulator of protein synthesis. The aim of this study was to investigate the role of Na/K-ATPase/mTOR signaling in myocardial TNF-α expression during endotoxemia. Results showed that treatment with LPS decreased Na/K-ATPase activity in the myocardium in vivo and in cultured neonatal cardiomyocytes. Inhibition of Na/K-ATPase by ouabain enhanced LPS-induced myocardial TNF-α protein production, but had no effect on TNF-α mRNA expression. More importantly, ouabain further decreased in vivo cardiac function in endotoxemic mice, which was blocked by etanercept, a TNF-α antagonist. LPS-induced reduction in Na/K-ATPase activity was prevented by inhibition of PI3K, Rac1 and NADPH oxidase using LY294002, a dominant-negative Rac1 adenovirus (Ad-Rac1N17) and apocynin, respectively. To assess the role of Rac1 in Ca²⁺ handling, Ca²⁺ transients in adult cardiomyocytes from cardiomyocyte-specific Rac1 knockout (Rac1^CKO) and wild-type (WT) mice were determined. LPS increased intracellular Ca²⁺ in WT but not in Rac1^CKO cardiomyocytes. Furthermore, LPS rapidly increased mTOR phosphorylation in cardiomyocytes, which was blocked by Rac1N17 and an inhibitor of calmodulin-dependent protein kinases (CaMKs) KN93, but enhanced by ouabain. Rapamycin, an inhibitor of mTOR suppressed TNF-α protein levels without any significant effect on its mRNA expression or global protein synthesis. In conclusion, myocardial Na/K-ATPase activity is inhibited during endotoxemia via PI3K/Rac1/NADPH oxidase activation. Inhibition of Na/K-ATPase activates Ca²⁺/CaMK/mTOR signaling, which promotes myocardial TNF-α protein production and cardiac dysfunction during endotoxemia.     

Maternally administered melatonin differentially regulates lipopolysaccharide-induced proinflammatory and anti-inflammatory cytokines in maternal serum, amniotic fluid, fetal liver, and fetal brain

Lipopolysaccharide (LPS) has been associated with adverse developmental outcome, including intra-uterine fetal death and intra-uterine growth retardation. In the LPS model, tumor necrosis factor alpha (TNF-alpha) is the major mediator leading to intra-uterine fetal death and intra-uterine growth retardation. Interleukin (IL)-10 protects rodents against LPS-induced intra-uterine fetal death and intra-uterine growth retardation. Melatonin is an immunomodulator. In the present study, we investigated the effect of maternally administered melatonin on LPS-induced proinflammatory and anti-inflammatory cytokines in maternal serum, amniotic fluid, fetal liver and fetal brain. The time pregnant mice were injected with melatonin [5.0 mg/kg, intraperitoneal (i.p.)] 30 min before LPS (500 microg/kg, i.p.) on gestational day 17. As expected, TNF-alpha, IL-1beta, IL-6 and IL-10 were obviously increased in maternal serum and amniotic fluid in response to LPS. In addition, maternal LPS exposure significantly increased the levels of TNF-alpha, IL-1beta, IL-6 and IL-10 in fetal liver, and TNF-alpha and IL-10 in fetal brain. Melatonin pretreatment significantly attenuated LPS-evoked elevation of TNF-alpha in maternal serum. On the contrary, melatonin aggravated LPS-induced increase in IL-10 in maternal serum. Melatonin had no effect on LPS-evoked IL-1beta and IL-6 in maternal serum and amniotic fluid. Interestingly, maternally administered melatonin also significantly attenuated LPS-evoked elevation of TNF-alpha in fetal brain, whereas the indole aggravated LPS-induced increase in IL-10 in fetal liver. Taken together, these results indicate that maternally administered melatonin differentially regulates LPS-induced proinflammatory and anti-inflammatory cytokines in maternal serum, amniotic fluid, fetal liver, and fetal brain.     

Lipopolysaccharide: a p38 MAPK-dependent disrupter of neutrophil chemotaxis

In sepsis, and in models of sepsis including endotoxemia, impaired neutrophil recruitment and chemotaxis have been reported. The inability of the endotoxemic neutrophil to chemotax could be attributed to the fact that intracellular signaling via LPS overrides signals from endogenous chemokines or, alternatively, that sequestration of neutrophils into lungs prevents access to peripheral tissues. Using both in vitro and in vivo chemotaxis assays the authors established that neutrophils from healthy mice chemotaxed in vivo toward MIP-2, whereas endotoxemic neutrophils did not. Since LPS activates leukocytes via the p38 MAPK pathway, SKF86002, a p38 MAPK inhibitor, was given to endotoxemic animals. SKF86002 significantly reversed the LPS-induced impairment in emigration of endotoxic neutrophils in response to MIP-2. Neutrophil chemotaxis in vitro was also impaired by LPS, via a p38 MAPK-dependent pathway, and this impairment could be reversed via p38 MAPK inhibition. Although neutrophil numbers dropped in the circulation and trapped in lungs during endotoxemia, SKF86002 did not reverse these parameters, demonstrating that p38 MAPK inhibition did not release trapped neutrophils from the lungs. In conclusion, the data suggest that the impaired emigration and chemotaxis of neutrophils at peripheral sites during endotoxemia may be partially due to a p38 MAPK-mediated inhibition of neutrophil responses to endogenous chemokines.