Adjuvant effects of beta-adrenergic drugs on indomethacin treatment of newborn canine endotoxic shock.

Newborns are susceptible to gram-negative sepsis/septic shock, but there is no established method of its treatment. This study was performed to evaluate the adjuvant effects of dopamine and dobutamine in the indomethacin treatment of newborn endotoxic shock. Endotoxic shock was induced in newborn dogs (2 to 10 days old; 300 to 800 g) by Escherichia coli lipopolysaccharide (LPS; 1.5 mg/kg, intravenously [IV]). Indomethacin (1.5 mg/kg, IV) was injected 5 minutes after LPS injection. Dopamine (5 micrograms/kg/min) or dobutamine (5 micrograms/mg/min) infusion started 5 minutes after LPS injection immediately following indomethacin injection. Hemodynamic parameters were monitored serially for 120 minutes. LPS induced bradycardia and hypotension, decreased the cardiac output and cardiac performance, and increased the total vascular resistance. When dopamine, dobutamine, or indomethacin were used alone, they attenuated the hemodynamic deterioration by LPS. Dopamine infusion following indomethacin administration improved the hemodynamics further, although dobutamine infusion did not. Therefore, we conclude that the adjuvant therapy of dopamine in the indomethacin treatment of newborn endotoxic shock is beneficial.     

蛋白激酶对内毒素休克后内皮细胞骨架的作用

目的　探讨内毒素休克发病机制中蛋白激酶G(PKG)的作用。　方法　用脂多糖 (LPS)刺激培养的内皮细胞 ,通过细胞裂解和离心获得细胞裂解液 ,用放射性同位素法标记法检测PKG的活性。同时采用特异性荧光染色法检测LPS刺激后细胞内肌动蛋白微丝 (F actin)的结构和分布变化。用PKG特异性抑制剂KT5 82 3预处理细胞后 ,再检测LPS介导的细胞内PKG活性和F actin的变化。以空白组为阴性对照 ,以PKG激动剂 8 Br cGMP刺激细胞作为阳性对照组。　结果　LPS分别刺激 5、10、30和 6 0min后细胞内PKG活力呈时间依赖性的增高 (与空白组相比P <0 .0 1) ,细胞内的F actin出现极性分布 ;而KT5 82 3预刺激 2 0min后再用LPS刺激没有出现上述变化。PKG的激动剂 8 Br cGMP刺激细胞后的变化与LPS的刺激相似。　结论　LPS可以介导血管内皮细胞PKG的激活和F actin的应力性变化 ;内毒素休克后内皮细胞通透性增高与cGMP PKG通路的激活有关。     

Lipopolysaccharide suppresses albumin expression by activating NF-kappaB in rat hepatocytes

BACKGROUND: The severity of hypoalbuminemia has been shown to be related to morbidity and mortality in critical illness, illustrating the need for better understanding of the molecular mechanism of hypoalbuminemia. Lipopolysaccharide(LPS) is a key mediator which induces hypoalbuminemia in sepsis and septic shock. The present studies were performed to identify whether the reduction of albumin expression induced by LPS was mediated by activating nuclear factor kappa B(NF-kappaB) in cultured rat hepatocytes. MATERIALS AND METHODS: Primary rat hepatocytes were divided into five groups treated with normal saline or 1 ng/ml, 0.01 microg/ml, 0.1 microg/ml, or 1 microg/ml of LPS for 24 h. The albumin level in the supernatant and NF-kappaB activity in hepatocytes were measured. Hepatocytes were pretreated for 30 min with SN50 (a highly selected inhibitor of NF-kappaB) at different concentrations (10, 30, and 50 microg/ml). After 24 h of treatment with 1 microg/ml of LPS, the culture medium was measured for albumin level. Meanwhile, NF-kappaB activity in hepatocytes was assayed. RESULTS: LPS dramatically decreased albumin expression and enhanced NF-kappaB activity in rat hepatocytes, especially in the 1 microg/ml LPS group. This reduction in albumin expression induced by LPS can be completely inhibited by SN50 in different concentrations, and the maximal increase in albumin was observed at a SN50 dosage of 30 microg/ml. CONCLUSIONS: The results suggest that LPS inhibits albumin expression by activating NF-kappaB signaling. NF-kappaB is a critical signaling pathway in LPS-induced hypoalbuminemia which it is worthwhile to understand in studying the molecular mechanism of hypoalbuminemia in sepsis and septic shock.     

血小板活化因子及其受体对颈髓损伤后血脊髓屏障损害的分子机制研究

目的：探讨血小板活化因子（ＰＡＦ）及其受体对颈髓损伤后血脊髓屏障损害的分子机制。方法：采用蛛网膜下腔注射ＰＡＦ及静脉注射ＰＡＦ受体拮抗剂ＢＮ５２０２１，应用地高辛标记ｃＤＮＡ探针原位杂交技术检测颈髓损伤后颈髓血管内皮细胞细胞间粘附分子－１ｍＲＮＡ（ＩＣＡＭ－１ｍＲＮＡ）和内皮细胞白细胞粘附分子－１ｍＲＮＡ（ＥＬＡＭ－１ｍＲＮＡ）表达。观察ＰＡＦ及其受体拮抗剂对颈髓损伤后血脊髓屏障、ＩＣＡＭ－１ｍＲＮＡ、ＥＬＡＭ－１ｍＲＮＡ表达的影响。结果：伤后颈髓血管内皮细胞ＩＣＡＭ－１ｍＲＮＡ、ＥＬＡＭ－１ｍＲＮＡ表达、伊文思蓝含量、水含量呈不同程度的增加；ＰＡＦ可使伤后血管内皮细胞ＩＣＡＭ－１ｍＲＮＡ、ＥＬＡＭ－１ｍＲＮＡ表达、伊文思蓝含量、水含量增加更为显著，ＰＡＦ受体拮抗剂可抑制ＩＣＡＭ－１ｍＲＮＡ、ＥＬＡＭ－１ｍＲＮＡ表达，降低颈髓组织伊文思蓝含量及水含量。结论：ＰＡＦ通过增加伤后颈髓血管内皮细胞粘附分子的表达是导致血脊髓屏障损害的重要分子基础。ＰＡＦ受体对伤后血管内皮细胞细胞粘附分子的表达具有调控作用。     

脑红蛋白在感染性休克早期大鼠脑组织中的动态变化

目的探讨感染性休克早期大鼠脑组织中脑红蛋白(neuroglobin,NGB)含量的动态变化在感染性休克中可能发挥的作用。方法健康雄性SD大鼠60只,12~15周龄,体重300~350g,随机分为两组,每组30只。M组经尾静脉注射脂多糖(LPS)10mg/kg制备大鼠感染性休克模型,当SBP下降幅度达到基础值的40%时认为感染性休克模型复制成功;C组给予等量生理盐水。分别在给LPS前(T_0)、给LPS后1h(T_1)、2h(T_2)、4h(T_3)、6h(T_4)采用ELISA法检测血清中TNF-α、IL-6浓度和NGB含量,Western blot法检测脑组织中NGB、半胱天冬酶-3(caspase-3)的含量。结果与C组比较,T1~T4时M组血清中的TNF-α、IL-6浓度明显增高(P0.05),脑组织中caspase-3含量明显增加(P0.05);T_3、T_4时血清和脑组织中NGB含量明显增高(P0.05)。结论感染性休克后大鼠脑组织发生了炎症损伤、细胞凋亡病理学改变,脑红蛋白在感染性休克所致的损伤脑组织中含量增加,推测其可能发挥了内源性神经保护功能。     

Hyper and hypodynamic models of sepsis in guinea pigs

The acute metabolic response following experimentally induced sepsis can generally be classified as either hypodynamic ("low flow") or hyperdynamic ("high flow"). We have found that in conscious guinea pigs the bolus infusion of 10(10) live Escherichia coli bacteria can elicit either response, depending on the route of administration of the bacteria. Intravenous infusion results in the hypodynamic condition of septic shock in which oxygen consumption (VO2) is reduced to approximately 60% of the control level, plasma glucose is elevated 4 hr after infusion with a reversal to extreme hypoglycemia 12 hr after infusion, and body temperature is reduced by approximately 5 degrees C in 12 hr. In contrast, subcutaneous injection results in increased VO2, body temperature, and plasma glucose. In both models the concentration of cortisol, catecholamines and glucagon were elevated, but the responses were more pronounced in the hypodynamic model. In both cases, insulin concentration was decreased. These models of sepsis are useful because many aspects of response are comparable to man, they are simple to create, and they are consistent and reproducible.     

Neutrophil CD18 expression and blockade after traumatic shock and endotoxin challenge.

OBJECTIVE: The expression of the leukocyte CD18 adhesion complex on polymorphonuclear leukocytes (PMNs) was measured, and the physiologic effects of blockade of the complex were studied after trauma and sepsis. SUMMARY BACKGROUND DATA: Margination of PMNs occurs early during inflammation and depends, in part, on expression of the CD18 adhesion complex. Blockade of this adherence complex can reduce PMN-mediated damage. This study tests the hypothesis that PMN activation after resuscitated trauma produces an occult endothelial injury that increases the vulnerability to a delayed inflammatory stimulus. METHODS: Anesthetized (fentanyl) mongrel pigs were sham injured or fluid resuscitated from soft tissue injury +35% hemorrhage. Systemic blood was collected at 24-hour intervals from awake animals. The CD18 density on circulating PMNs was determined with flow cytometry using mean channel fluorescence (MCF). The CD18 receptors were blocked with monoclonal antibodies either immediately before trauma or immediately before an endotoxin (lipopolysaccharide [LPS]) challenge that was administered to all groups 3 days after the shock episode. Bronchoscopy was performed before trauma, pre-LPS, and post-LPS, and protein content was measured in bronchoalveolar lavage (BAL). RESULTS: Mean channel fluorescence was reduced on PMNs for 48 hours in animals with trauma versus animals with sham injuries. Anti-CD18 therapy produced higher circulating PMN counts compared with nontreated sham or shock groups. The incremental rise of BAL protein after shock was prevented with anti-CD18; the increment after LPS was attenuated. Anti-CD18 was administered before trauma and reduced the fluids necessary to maintain cardiac filling pressures after LPS. CONCLUSIONS: These data suggest that PMNs are activated after resuscitation from traumatic shock and that these cells produce an endothelial injury that may increase the vulnerability to a septic challenge. The broad implication is that temporarily blocking PMN adhesiveness at the time of trauma might salvage some host tissue and reduce the incidence of septic complications in the post-trauma period.     

Plasma beta-endorphin immunoreactivity in dogs during anesthesia, surgery, Escherichia coli sepsis, and naloxone therapy

To improve understanding of the role of endorphins in septic shock, we examined the effects of anesthesia, splenectomy, live Escherichia coli infusion, and treatment with naloxone, respectively, on plasma beta-endorphin immunoreactivity (beta-EI) and plasma cortisol in dogs. Baseline levels of plasma beta-EI and cortisol were established in awake dogs. Pentobarbital anesthesia alone did not affect plasma beta-EI, but splenectomy was followed by a significant (P less than 0.001) rise in both plasma beta-EI and cortisol. Infusion of saline over a 3-hour period following splenectomy induced no further increase in plasma beta-EI, but infusion of live E. coli in splenectomized dogs caused a further rise in plasma beta-EI (P less than 0.02). Following induction of septic shock in a separate group of splenectomized animals, treatment with naloxone (3 mg/kg bolus and 2 mg/kg/hr infusion) did not alter the rise in plasma beta-EI. These results confirm release of beta-endorphin during septic shock and further implicate the hypothalamic-pituitary-adrenal axis in its pathophysiology. Based on the finding that naloxone did not affect the dynamics of plasma beta-EI, mechanisms are postulated to explain the therapeutic value of this drug in septic shock.     

Lipopolysaccharide impairs endothelial nitric oxide synthesis in rat renal arteries

BACKGROUND: Impaired endothelium-dependent vasodilation may contribute to hypoperfusion and failure of abdominal organs, including the kidneys during endotoxin or septic shock. In this study, the short-term (2 h) effects of bacterial lipopolysaccharide (LPS) on endothelium-dependent vasodilation in rat renal and superior mesenteric arteries were documented. METHODS: Rat renal and mesenteric arteries were dissected and exposed in vitro to LPS for two hours. The effects of LPS on vascular reactivity were determined and compared with time-matched controls. Endothelial nitric oxide (NO) release was determined using an NO microsensor in adjacent vessel segments. RESULTS: LPS impaired maximal acetylcholine (ACh)-induced endothelium-dependent vasodilation in renal arteries (62.5 +/- 8.8% vs. 34.4 +/- 7.5% in controls and LPS-exposed arteries), but not in mesenteric arteries. LPS did not alter the sensitivity of renal arteries to exogenous NO. ACh-dependent vasodilation was abolished after blocking NO synthesis with 10-4 mol/L L-NA in control and LPS-incubated renal arteries. When compared with controls, NO release induced by ACh and the receptor-independent calcium ionophore A23187 was significantly decreased (P < 0.05) in LPS-exposed renal segments and was fully abolished in endothelium-denuded segments, indicating that LPS attenuated receptor-dependent as well as receptor-independent endothelial NO release. In contrast, ACh- and A23187-induced NO release was normal in LPS-exposed mesenteric arteries. CONCLUSIONS: These results indicate that LPS-induced selective impairment of ACh-induced endothelium-dependent relaxation in rat renal arteries is caused by decreased endothelial NO release. This may contribute to the propensity for acute renal failure during septic shock.     

The protective effects of early treatment with propofol on endotoxin-induced acute lung injury in rats

To investigate the effects of treatment with propofol administration at different time point in acute lung injury of endotoxin-induced shock rats. METHODS: 76 male wistar rats were randomly assigned to five groups: A) control group; B) endotoxemic group, receiving intravenous lipopolysaccharide (LPS) 8 mg.kg-1; C) pretreatment group, treated identically to endotoxemic group with the additional administration of propofol (5 mg.kg-1 bolus, followed by infusion at 10 mg.kg-1.h-1) of 1 hr prior to the injection of LPS; D) simultaneously treatment group, treated identically to endotoxemic group with the additional administration of propofol simultaneously with the injection of LPS; E) post-treatment group, which was treated identically to endotoxemic group except for administration of propofol 1 hr after the injection of LPS. PaO2, pH, MAP and survival rate were recorded and plasma NO, TNF-alpha were measured during 5-hr after the injection of LPS. After the rats were killed, lung tissue was sampled to measured expression of inducible nitric oxide synthase (iNOS), nitrotyrosine (NT), myeloperoxidase (MPO) activity, malondialdehyde (MDA), wet-to-dry lung weight ratio (W/D), and pulmonary permeability index (PPI). RESULTS: Compared with the endotoxemic group, both the pretreatment and simultaneously treatment groups, significantly improved PaO2, pH, MAP and 5th hour survival rate of rats, and attenuated endotoxin-induced increased iNOSmRNA, NT expression, MPO activity and MDA level in lung tissue, and decreased pulmonary microvascular permeability, TNF-alpha, NO in plasma. But these beneficial efficacies were blunted in the post-treatment group. CONCLUSIONS: These findings showed that propofol administration may provide protective effects on acute lung injury in endotoxin-induced shock.     

Vasodilatory septic shock refractory to catecholamines: is there a role for terlipressin?

We report two patients in vasodilatory septic shock refractory to catecholamines in which a continuous infusion of terlipressin was associated with a dramatic increase in systemic arterial blood pressure and short-term survival. Low doses of terlipressin were sufficient in both cases (0.01-0.0 mg h(-1)) to restore blood pressure by increase of systemic vascular resistances. The haemodynamic response was immediate, long-acting, dose-dependent and reversible in a few hours when the drug administration was stopped. A further increase in terlipressin dose regimen markedly decreased cardiac performance. Terlipressin simultaneously induced vasoconstriction within the cutaneous vascular territory, leading to local skin necrosis. The splanchnic vascular territory seemed to be constricted in the same way. Further studies are needed to better understand and precise the role of terlipressin in the treatment of vasodilatory septic shock refractory to catecholamines.     

Prolonged methylene blue infusion in refractory septic shock: a case report

Purpose

Methylene blue (MB) has been advocated for the treatment of refractory hemodynamic instability in patients with septic shock. However, the use of MB infusions in septic shock is not considered standard treatment, and the available literature describes infusions of short duration, typically less than six hours.

Clinical features

We report a case of septic shock in a 67-yr-old male who required maximal vasopressor support with norepinephrine, epinephrine, and vasopressin. Despite standard protocols for the treatment of septic shock, the patient’s hemodynamic status was refractory 80 hr post admission. However, initiation of a MB infusion resulted in the rapid restoration of hemodynamic stability and a subsequent decrease in vasopressor requirements. Multiple attempts to discontinue the MB infusion resulted in immediate and repeated increases in vasopressor requirements, necessitating a continuous infusion with a slow taper of MB for 120 hr. Ultimately, the patient survived the illness and was discharged home. We observed no adverse events that could be attributed to the use of MB.

Conclusion

In our patient, the use of MB resulted in hemodynamic stability unattained with standard vasopressor support. Further research is warranted on the use of MB in patients with septic shock.     

Deleterious effect of zinc in a pig model of acute endotoxemia.

By antiapoptotic effects and the induction of the heat-shock response, zinc is supposed to be a promising means of therapy during sepsis. As zinc also stimulates the expression of proinflammatory cytokines, its administration during the proinflammatory stage of septic shock might have adverse effects. Therefore, this study analyzes the influence of zinc during the acute phase of endotoxemia. In a pig model of acute endotoxemia, animals were divided into two groups: group I (n = 5) with saline treatment and group II (n = 5) with zinc treatment in close succession to lipopolysaccharide (LPS) (1.0 mu g/kg Escherichia coli endotoxin WO 111:B4). Hemodynamic and pulmonary monitoring was followed by combined reflection photometry, pulse oxymetry, blood gas samples, and temperature measurement. Plasma concentrations of tumor necrosis factor (TNF)alpha and interleukin (IL)-6 were analyzed by enzyme-linked immunosorbent assay (ELISA). Morphology included the weight of the lungs, the width of the alveolar septae, and the paracentral necrosis rate of the liver. After LPS infusion, group II (zinc) showed an impressive and significant deterioration of all pulmonary and most of the hemodynamical parameters compared to group I (saline). Levels of TNFalpha and IL-6 measured were significantly higher after zinc treatment. In accordance, we found significant more morphologic damages in group II (zinc). The almost simultaneous infusion of zinc and LPS complementary induced proinflammatory effects with a deleterious outcome. The same potentials characterizing zinc as a promising tool of prophylactic therapy in sepsis seem to ban its use during the acute phase.     

Differential expression of inducible nitric oxide synthase in septic shock

During cardiopulmonary bypass (CPB), the septic patient has markedly decreased peripheral vascular resistance as a consequence of endotoxin release from microorganisms. This decrease in peripheral vascular resistance is the result of endotoxin-induced nitric oxide (NO) produced by inducible nitric oxide synthase (iNOS) and endothelial nitric oxide synthase (eNOS). iNOS and eNOS are responsible for the synthesis of NO because of various stimuli, including the bacterial endotoxin, lipopolysaccharide (LPS). We tested the hypothesis that a differential expression of iNOS among human endothelial cells and murine macrophage is dependent upon exposure to endotoxin and various pro-inflammatory cytokines. Using a human endothelial cell line, ECV-304 and murine macrophage cell line, RAW 264.7, we quantified the expression of iNOS with specific FITC-conjugated antibodies using fluorescence activated cell sorter (FACS) and NO production with a Bioxytech nitric oxide spectrophotometric assay. This in vitro septic model utilized LPS supported with species-specific interferon-gamma, interleukin-1 beta, and tumor necrosis factor-alpha. The cell type were stimulated for 8 hours with combinations of the cytokines mentioned. The FACS data demonstrated a significant stimulus-dependent increase in iNOS expression among the macrophage groups; however, the stimulated endothelial cells showed no significant change in iNOS expression. The nitric oxide production data demonstrated significant increases in NO production among macrophage stimulated groups; whereas, endothelial stimulated groups exhibit no significant change. We conclude that NO secreted during septic shock is the result of activated macrophage, not the endothelium. The clinical relevance is that the more severe the infectious process, the lower the PVR may be during CPB because of increased NO production from activated macrophage.     

Synergistic therapeutic potential of dexamethasone and L-arginine in lipopolysaccharide-induced septic shock

BACKGROUND: Dexamethasone (DEX) is demonstrated to have anti-inflammatory properties and known to induce hemodynamic improvement in sepsis and septic shock. L-arginine (L-arg), a semi-essential amino acid, depending on its metabolic pathway, becomes very essential in stress situations such as heatstroke, burns, sepsis, trauma, and wound healing. The aim of this study was to evaluate the synergistic therapeutic effect of DEX and L-arg in rescuing the mice from experimental septic shock induced by bacterial lipopolysaccharide (LPS). The experiments were designed to delineate the molecular mechanisms responsible for the increased therapeutic benefit of the combination therapy (CT) in LPS-induced septic shock. METHODS: Acute endotoxemia was induced in Swiss male mice by i.p. injection of LPS (18 mg kg(-1)) at 0 h. LPS-treated mice were divided into four groups. The first group (DEX group) received DEX (2 mg kg(-1)) i.p. at +2 h of LPS. The second group (L-arg group) received L-arg i.p. at a dose of 120 mg/kg at +6 h of LPS injection. The third group (CT group) received DEX (2 mg kg(-1)) at +2 h LPS followed by L-arg at +6 h of LPS injection. The fourth group received saline in place of L-arg or DEX (LPS group). A sham group was also included, where normal mice received saline in place of LPS or L-arg or DEX. At +6 h, mice from sham group, LPS group, and DEX group were sacrificed at +24 h. Mice from sham group, DEX group, L-arg group, and CT group were sacrificed to examine various parameters associated with LPS endotoxemia. RESULTS: The CT with DEX followed by L-arg significantly increased the survival of mice injected with a lethal dose of LPS. Monotherapy with either DEX or L-arg given at the same dose and time did not increase the survival of the mice injected with LPS. DEX administration could significantly reduce the levels of serum TNF-alpha, IL-1beta, IFN-gamma, aspartate aminotransferase (ASAT), alanine aminotransferase (ALAT), and nitrite. DEX also down-regulated the expression of liver-inducible nitric oxide synthase (iNOS), and up-regulated the levels of serum anti-inflammatory cytokines like TGF-beta1 and IL-4, hepatic and splenic arginase, in LPS-injected mice. The enhanced therapeutic effect of CT correlated with reduced pathological symptoms, decreased Th1 cytokines, increased TGF-beta1 and arginase levels compared to the mice administered with either of the monotherapies. The CT group had significantly increased expression of hepatic Hsp 70 and reduced septic shock associated histopathology, in lung and liver, compared to the mice treated with either DEX or L-arg. CONCLUSIONS: The therapeutic combination therapy with DEX and L-arg, at the appropriate dose, time, and sequence of administration, changed the cytokine profile, in favor of reducing the inflammatory response. The significantly enhanced survival observed in the CT group was accompanied by an increased hepatic Hsp 70, hepatic arginase, splenic arginase, and decreased organ injury. This novel concept of combined therapy could form the basis of an effective therapeutic approach in the treatment of sepsis and septic shock.     

丙酮酸乙酯对脓毒症休克犬肠黏膜屏障功能的保护作用

目的探讨丙酮酸乙酯（EP）对脓毒症休克犬肠黏膜屏障功能的影响。方法健康雄性杂种犬20只，内毒素（LPS）静脉注射复制犬脓毒症休克模型，随机分为对照组（8只）和EP组（12只）。对照组只接受林格液复苏。EP组另外给予丙酮酸乙酯首剂0．05g／kg．然后按0．05g·kg^-1·h^-1持续泵入。脓毒症休克模型建立前及建立后0、8、12和24h取血测定血浆二胺氧化酶（DAO）活性和血浆D-乳酸含量，试验24h处死动物后取小肠标本，进行肠黏膜炎性损伤病理学评分。结果EP组犬的肠黏膜炎性损伤程度病理学评分为2．33±0．25，明显轻于模型组的3．39±0．38，两组比较，差异有统计学意义（P〈0．05）。两组实验犬在休克后血浆D-乳酸含量和DAO活性逐渐升高，对照组较EP组升高更为明显（P〈0．05）。结论EP能显著改善肠组织灌流及功能指标，减轻肠黏膜的病理损害，对脓毒症休克时小肠有保护作用。     

Synthetic retinoids improve survival in rodent model of endotoxic shock.

OBJECTIVE: To investigate the effect of synthetic retinoids on septic shock induced by lipopolysaccharide (LPS) in rats. DESIGN: Randomised study. SETTINGS: University hospital laboratory, Sweden. ANIMALS AND INTERVENTIONS: 31 male Sprague Dawley rats randomised into four groups: controls, given vehicle alone (n = 6), LPS 6 mg/kg body weight alone (n = 12), and LPS 6 mg/kg but pretreated with the retinoic acid receptor-alpha (RAR-alpha) agonists CD336 (n = 6) and CD2081 (n = 7). MAIN OUTCOME MEASURES: Arterial blood pressure and heart rate measured hourly for four hours; mortality. RESULTS: LPS caused a pronounced fall in blood pressure within one hour of injection in all groups of rats. Of the 12 rats given LPS but not RAR-alpha agonists, 6 died before the end of the experiment. By contrast, all animal given either CD336 or CD2081 survived. The significantly improved survival was found despite no significant improvements in either mean arterial pressure or heart rate. CONCLUSION: Pretreatment with selective synthetic RAR-alpha agonists improves survival after LPS-induced septic shock in rats. These agents may have therapeutic potential in the treatment of septic shock in humans.     

Effects of human cathelicidin antimicrobial peptide LL-37 on lipopolysaccharide-induced nitric oxide release from rat aorta in vitro

BACKGROUND: Lipopolysaccharides (LPS), released by Gram-negative bacteria, cause vascular expression of inducible nitric oxide synthase (iNOS) leading to nitric oxide (NO) production and septic shock. Human cathelicidin antimicrobial peptide (LL-37) can bind and neutralize LPS. We wanted to study whether LL-37 affects LPS or interleukin-1beta (IL-1beta)-induced production, release and function of NO in intact rat aorta rings and cultured rat aorta smooth muscle cells. METHODS: Isolated segments of thoracic aorta and cultured cells were incubated in the presence of LPS, LL-37, LPS + IL-37, IL-1beta, IL-1beta + IL-37 or in medium alone. Smooth muscle contraction in response to phenylephrine and accumulation of the sdegradation products of NO, nitrate and nitrite, were measured on aorta segments. Levels of iNOS were assessed by Western blot and cytotoxic effects were detected by measurement of DNA fragmentation in cultured cells. Number of viable cells were determined after Trypan blue treatment. RESULTS: Both LPS and IL-1beta reduced contractility in response to phenylephrine and increased NO production as well as iNOS expression. LL-37 inhibited the LPS depression of vascular contractility induced only by LPS. LL-37 reduced both the LPS- and IL-1beta-induced NO production and iNOS expression. LL-37 at high concentrations induced DNA fragmentation and decreased the number of living cells. CONCLUSION: IL-37 reduces NO production induced by LPS and IL-1beta. The reduction does not seem to result only from neutralization of LPS but also from a cytotoxic effect, possibly via induction of apoptosis.