Alpha-melanocyte-stimulating hormone protects against renal injury after ischemia in mice and rats.

Reperfusion after ischemia induces cytokines, chemoattractant chemokines, adhesion molecules, and nitric oxide (NO). The resultant neutrophil adherence and NO potentiates renal injury. alpha-Melanocyte-stimulating hormone (alpha-MSH) is a potent anti-inflammatory agent that inhibits neutrophil migration and production of neutrophil chemokines and NO. Since neutrophils and NO promote renal ischemic injury, we sought to determine if alpha-MSH inhibits renal injury in a model of bilateral renal ischemia. alpha-MSH significantly reduced ischemia-induced renal damage, measured by changes in renal histology and plasma blood urea nitrogen and creatinine in mice. alpha-MSH significantly decreased tubule necrosis, neutrophil plugging, and capillary congestion. Delay of alpha-MSH treatment for 6 h after ischemia also significantly inhibited renal damage. alpha-MSH also significantly inhibited ischemic damage in rats. To begin to determine the mechanism of action of alpha-MSH, we measured its effects on mediators of neutrophil trafficking and induction of the inducible isoform of NO synthase-II. alpha-MSH inhibited ischemia-induced increases in mRNA for the murine neutrophil chemokine KC/IL-8. alpha-MSH also inhibited induction of mRNA for the adhesion molecule ICAM-1, which is known to be critical in renal ischemic injury. alpha-MSH inhibited nitration of kidney proteins and induction of NO synthase-II. We conclude: (a) alpha-MSH protects against renal ischemia/reperfusion injury; and (b) it may act, in part, by inhibiting the maladaptive activation of genes that cause neutrophil activation and adhesion, and induction of NO synthase.     

Effect of thalidomide on signal transduction pathways and secondary damage in experimental spinal cord trauma

TNF-alpha seems to play a central role in the inflammatory process of spinal cord injury. We tested the neuroprotective effects of thalidomide, an immunomodulatory agent that inhibits TNF-alpha production, which have not been investigated so far. The aim of our study was to evaluate the therapeutic efficacy of thalidomide in an experimental model of spinal cord trauma, which was induced by the application of vascular clips (force of 24 g) to the dura via a 4-level T5 to T8 laminectomy. Spinal cord injury in mice resulted in severe trauma characterized by edema, neutrophil infiltration, and cytokine production that is followed by recruitment of other inflammatory cells, production of a range of inflammation mediators, tissue damage, apoptosis, and disease. Thalidomide treatment significantly reduced the degree of: 1) spinal cord inflammation and tissue injury (histological score); 2) neutrophil infiltration (myeloperoxidase evaluation); 3) iNOS, nitrotyrosine, lipid peroxidation, and cytokine expression (TNF-alpha and IL-1beta); 4) apoptosis (terminal deoxynucleotidyltransferase-mediated UTP end labeling staining, and Bax and Bcl-2 expression); and 5) nuclear factor-kappaB activation. In a separate set of experiments, we have also clearly demonstrated that thalidomide significantly ameliorated the recovery of limb function (evaluated by motor recovery score). Taken together, our results clearly demonstrate that treatment with thalidomide reduces the development of inflammation and tissue injury events associated with spinal cord trauma.     

Local stimulation of alpha7 cholinergic receptors inhibits LPS-induced TNF-alpha release in the mouse lung

The cholinergic nervous system can inhibit the release of proinflammatory cytokines such as TNF-alpha from LPS-stimulated macrophages. Acetylcholine, the principal neurotransmitter of the vagus nerve, is the key mediator of this so-called cholinergic anti-inflammatory pathway, specifically interacting with alpha7 cholinergic receptors expressed by macrophages and other cell types to inhibit TNF-alpha production. The aim of the current study was to determine the capacity of the selective alpha7 cholinergic receptor agonist 3-(2,4-dimethoxybenzylidene) anabaseine (GTS-21), administered locally into the airways, to inhibit LPS-induced inflammatory responses in the mouse lung in vivo. GTS-21 dose-dependently inhibited LPS-induced TNF-alpha release by MH-S mouse alveolar macrophages in vitro. Intranasal inoculation with GTS-21 also dose-dependently inhibited TNF-alpha release into the lung compartment after intrapulmonary delivery of LPS in mice in vivo, whereas IL-6 concentrations were not affected. However, GTS-21 did not influence the influx of neutrophils into bronchoalveolar lavage fluid elicited by LPS and increased the concentrations of the neutrophil-attracting chemokines cytokine-induced neutrophil chemoattractant and macrophage inflammatory protein 2. These data indicate that local administration of GTS-21 inhibits TNF-alpha release in the lung during LPS-induced inflammation.     

Differential Neutrophil Infiltration Contributes to Regional Differences in Brain Infiammation in the Substantia Nigra Pars Compacta and Cortex

脑的炎症反应是神经退行性疾病的危险因素之一。有趣的是,黑质密部(SNpc)严重的炎性反应会加速帕金森病的发作和进展。本研究通过比较SNpc与皮质的炎性过程来检测SNpc严重炎性反应的潜在机制。在完整的脑组织中,SNpc和皮质的CD11b+小胶质细胞密度是相似的。但是,脂多糖注射可增加SNpc的CD11b+细胞数目,而不能增加皮质中的。以前作者曾报道内毒素注射之后,黑质密部有CD11b和MPO双阳性的中性粒细胞浸润(GLIA55:1577-1588)。值得注意的是,MPO+中性粒细胞数量在SNpc中显著增加,而在皮质中只有轻微提高。中性粒细胞浸润的范围与神经元损伤相关。作者证实,内毒素注射后,中性粒细胞减少大鼠的SNpc中的神经元丢失较正常大鼠显著减少。此外,完整的SNpc中的星形胶质细胞密度明显低于皮质。而且,内毒素注射后,SNpc的内皮细胞和星形胶质细胞的损害以及血脑屏障的通透性均有显著变化。这些结果都提示,过度的中性粒细胞浸润和环境因子,例如低星形胶质细胞浓度和高血脑屏障通透性,会导致SNpc的重度炎症和神经元死亡。     

Calcitonin gene-related peptide inhibits local acute inflammation and protects mice against lethal endotoxemia

Calcitonin gene-related peptide (CGRP), a potent vasodilatory peptide present in central and peripheral neurons, is released at inflammatory sites and inhibits several macrophage, dendritic cell, and lymphocyte functions. In the present study, we investigated the role of CGRP in models of local and systemic acute inflammation and on macrophage activation induced by lipopolysaccharide (LPS). Intraperitoneal pretreatment with synthetic CGRP reduces in approximately 50% the number of neutrophils in the blood and into the peritoneal cavity 4 h after LPS injection. CGRP failed to inhibit neutrophil recruitment induced by the direct chemoattractant platelet-activating factor, whereas it significantly inhibited LPS-induced KC generation, suggesting that the effect of CGRP on neutrophil recruitment is indirect, acting on chemokine production by resident cells. Pretreatment of mice with 1 mug of CGRP protects against a lethal dose of LPS. The CGRP-induced protection is receptor mediated because it is completely reverted by the CGRP receptor antagonist, CGRP 8-37. The protective effect of CGRP correlates with an inhibition of TNF-alpha and an induction of IL-6 and IL-10 in mice sera 90 min after LPS challenge. Finally, CGRP significantly inhibits LPS-induced TNF-alpha released from mouse peritoneal macrophages. These results suggest that activation of the CGRP receptor on macrophages during acute inflammation could be part of the negative feedback mechanism controlling the extension of acute inflammatory responses.     

Plasma concentrations and anti-L-cytokine effects of alpha-melanocyte stimulating hormone in septic patients

OBJECTIVES: The aim of this research was to investigate endogenous concentrations and anti-cytokine effects of the antiinflammatory peptide alpha-melanocyte stimulating hormone (alpha-MSH) in patients with systemic inflammation. The objectives were to determine the following: changes over time of plasma alpha-MSH and relationship with patient outcome, correlation between plasma alpha-MSH and tumor necrosis factor (TNF)-alpha plasma concentration and production in whole blood samples, and influences of alpha-MSH on production of TNF-alpha and interleukin (IL)-1beta in whole blood samples stimulated with lipopolysaccharide (LPS). DESIGN: Prospective, nonrandomized, clinical study. SETTING: Intensive care unit of a university hospital. PATIENTS: A total of 21 patients with sepsis syndrome/septic shock and an equal number of healthy volunteers. INTERVENTIONS: Circulating alpha-MSH and TNF-alpha concentrations and TNF-alpha production in supernatants of LPS (1 ng/mL)-stimulated whole blood were measured repeatedly. To determine whether alpha-MSH can modulate production of TNF-alpha and IL-1 beta, these cytokines were measured in whole blood samples stimulated with LPS (1 ng/mL) in the presence or absence of concentrations of the peptide. MEASUREMENTS AND MAIN RESULTS: Plasma alpha-MSH was low in early samples and gradually increased in patients who recovered but not in those who died. There was a negative correlation between plasma concentrations of alpha-MSH and TNF-alpha. In blood samples taken at early phases of sepsis syndrome, production of TNF-alpha was reduced relative to control values; such production increased in patients who recovered but not in those who died. Addition of alpha-MSH to LPS-stimulated whole blood samples inhibited production of TNF-alpha and IL-1beta in a concentration-dependent manner. CONCLUSIONS: In patients with systemic inflammation, there are substantial changes over time in plasma concentrations of alpha-MSH that are reduced in early phases of the disease. Reduction of this endogenous modulator of inflammation could be detrimental to the host. Addition of alpha-MSH to LPS-stimulated blood samples reduces production of cytokines involved in development of septic syndrome. This inhibition by alpha-MSH, a peptide that is beneficial in treatment of experimental models of sepsis, might therefore be useful to treat sepsis syndrome in humans.     

Comparison of the effects of aging and IL-6 on the hepatic inflammatory response in two models of systemic injury: scald injury versus i.p. LPS administration

Regardless of age, a marked elevation in circulating IL-6 levels correlates with increased mortality after injury or an inflammatory challenge. We previously reported that aged IL-6 knockout mice given LPS have improved survival and reduced inflammatory response than LPS-treated aged wild type (WT) mice. Herein, we analyzed the effects of aging and IL-6 on the hepatic inflammatory response in two models of systemic injury: dorsal scald (burn) injury versus intraperitoneal LPS administration. At 24 h after burn injury, circulating alanine aminotransferase and hepatic neutrophil accumulation were comparable regardless of age or IL-6 deficiency. However, at this same time point, these indicators of liver damage, in addition to hepatic levels of KC, a neutrophil chemoattractant, were increased in aged WT mice given LPS relative to young WT mice given LPS. The hepatic injury was drastically reduced in aged IL-6 knockout mice given LPS as compared with LPS-exposed aged WT mice. Our results suggest that the nature of the insult will determine the degree of remote injury in aged animals. In addition, the role of IL-6 as a contributing factor of tissue injury may be insult specific.     

Ventilator-induced injury augments interleukin-1beta production and neutrophil sequestration in lipopolysaccharide-treated lungs

Mechanical ventilators are commonly used to support critically ill patients; however, inappropriate ventilator settings might initiate or augment lung injury. To determine whether a large tidal volume (Vt) augments inflammatory responses and neutrophil sequestration in the lungs of rats receiving intratracheal lipopolysaccharides (LPS). Rats received intratracheal instillation of LPS (0.5 mg/kg) followed by 4 h of mechanical ventilation (MV) at 60 strokes per min with a Vt of 10 mL/kg as control MV, or 30 strokes per min with a Vt of 20 mL/kg of body weight as high-volume MV (HMV). In addition, monoclonal antibodies against rat intercellular adhesion molecule 1 (ICAM-1) or immunoglobulin G (50 mg/kg) were administered 30 min before LPS instillation and MV. Our study demonstrates that HMV enhances pulmonary permeability and induces neutrophil recruitment into the alveolar space and pulmonary edema. Intratracheal instillation of LPS caused marked lung injury, neutrophil recruitment, and production of cytokines and chemokines. Combining LPS instillation and HMV synergistically upregulated interleukin 1beta (IL-1beta) production and neutrophil sequestration in lung tissues. The ICAM-1 expression in lung tissues was responsible for the synergistic effects of neutrophil sequestration. Synergistic upregulation of IL-1beta production and neutrophil sequestration was attenuated by blocking ICAM-1 by neutralizing antibody pretreatment. High Vt MV in LPS-injured lung causes synergistic production of IL-1beta and sequestration of neutrophil via ICAM-1-dependent effects.     

Stimulation of alpha 7 cholinergic receptors inhibits lipopolysaccharide-induced neutrophil recruitment by a tumor necrosis factor alpha-independent mechanism

The cholinergic nervous system controls inflammation by inhibiting the release of proinflammatory cytokines such as tumor necrosis factor (TNF) alpha from lipopolysaccharide (LPS)-stimulated macrophages. The key endogenous mediator of this so-called cholinergic anti-inflammatory pathway is acetylcholine, the principal neurotransmitter of the vagus nerve, which specifically interacts with alpha7 cholinergic receptors expressed by macrophages and other cell types to inhibit TNF-alpha production. We here investigated the capacity of the selective alpha7 cholinergic receptor agonist 3-(2,4-dimethoxybenzylidene) anabaseine (GTS-21) to inhibit LPS-induced inflammatory responses in mice in vivo. To this end, mice received an intraperitoneal injection of LPS (from Escherichia coli, 200 microg) preceded by GTS-21 (4 mg/kg) or vehicle. GTS-21 strongly inhibited LPS-induced TNF-alpha release into the peritoneal cavity and the circulation. In addition, GTS-21 attenuated the influx of neutrophils into peritoneal fluid upon administration of LPS. This inhibitory effect on neutrophil recruitment by GTS-21 was independent of its effect on TNF-alpha release, considering that etanercept, a potent TNF-alpha-blocking protein containing the extracellular domain of the p75 TNF-alpha receptor, did not influence LPS-induced neutrophil influx either in the presence or in the absence of GTS-21 treatment. GTS-21 did not reduce the local secretion of macrophage inflammatory protein 2 and keratinocyte-derived cytokine, suggesting that altered concentrations of these neutrophil-attracting chemokines did not contribute to GTS-21-induced inhibition of neutrophil migration. These data identify a novel anti-inflammatory effect of chemical alpha7 cholinergic receptor stimulation that is independent from its capacity to inhibit TNF-alpha production.     

山莨菪碱抗肝脏缺血再灌注损伤的实验研究

目的　探讨山莨菪碱对大鼠肝脏缺血损伤的保护作用及其机制。方法　测定大鼠肝脏缺血再灌注(模型组)和预防性应用山莨菪碱(预防组)时胆汁流量、肝组织丙二醛(MDA)含量及肝脏组织学改变和中性粒细胞浸润程度。结果　预防组与模型组相比,胆汁流量显著增加(P＜0.01),MDA含量显著降低(P＜0.01),预防组肝脏组织学变化较轻,白细胞浸润较少。结论　山莨菪碱具有对肝脏缺血再灌注损伤明显的保护作用,其作用机制可能是抑制自由基的产生。     

Regulation of neutrophils by interferon-γ limits lung inflammation during tuberculosis infection

Resistance to Mycobacterium tuberculosis requires the host to restrict bacterial replication while preventing an over-exuberant inflammatory response. Interferon (IFN) γ is crucial for activating macrophages and also regulates tissue inflammation. We dissociate these two functions and show that IFN-γ(-/-) memory CD4(+) T cells retain their antimicrobial activity but are unable to suppress inflammation. IFN-γ inhibits CD4(+) T cell production of IL-17, which regulates neutrophil recruitment. In addition, IFN-γ directly inhibits pathogenic neutrophil accumulation in the infected lung and impairs neutrophil survival. Regulation of neutrophils is important because their accumulation is detrimental to the host. We suggest that neutrophilia during tuberculosis indicates failed Th1 immunity or loss of IFN-γ responsiveness. These results establish an important antiinflammatory role for IFN-γ in host protection against tuberculosis.     

Fenofibrate Attenuates Neutrophilic Inflammation in Airway Epithelia: Potential Drug Repurposing for Cystic Fibrosis

A hallmark of cystic fibrosis (CF) lung disease is neutrophilic airway inflammation. Elevated neutrophil counts have been associated with decreased forced expiratory volume in 1 second and poor clinical measures in patients with CF. Interleukin 8 (IL‐8), epithelial neutrophil activating protein 78 (ENA‐78), tumor necrosis factor alpha (TNF‐α), granulocyte macrophage colony‐stimulating factor (GM‐CSF), and granulocyte colony‐stimulating factor (G‐CSF) contribute to neutrophil activation and disease pathogenesis in the airways of patients with CF. Drugs that modify the production of these chemokines in the airways could potentially benefit CF patients. Thus, we determined the effects of fenofibrate on their production in cell populations obtained from the airways. Human small airway epithelial cells and CF bronchial epithelial cells were treated with IL‐1β to induce inflammation. We cotreated the cells with fenofibrate at concentrations ranging from 10 to 50 μM to determine if this drug could attenuate the inflammation. IL‐8, ENA‐78, TNF‐α, GM‐CSF, and G‐CSF production were measured from the cell culture supernates by ELISA. ANOVA statistical testing was conducted using SPSS 17.0. IL‐1β increased the production of each of the chemokines by several fold. Fenofibrate reduced IL‐1β induced production of each of these neutrophilic chemokines at the concentrations used. IL‐1β increases the production of neutrophilic chemokines in airway epithelial cells. Cotreatment with fenofibrate blunts these processes. Fenofibrate should be explored as a therapeutic option to modulate the abundant neutrophilic inflammation observed in CF.     

Regulation of adenovirus-mediated elafin transgene expression by bacterial lipopolysaccharide

Lipopolysaccharide (LPS) is a mediator of inflammatory lung injury. Selective augmentation of host defense molecules such as elafin (an elastase inhibitor with antimicrobial activity) at the onset of pulmonary inflammation is an attractive potential therapeutic strategy. The aim of this study was to determine whether elafin expression could be induced by LPS administered after transfection with adenovirus (Ad) encoding human elafin downstream of the murine cytomegalovirus (CMV) promoter (known to be potentially responsive to LPS). In addition, we aimed to determine the effect of local elafin augmentation on neutrophil migration to the lung. LPS significantly up-regulated elafin expression from pulmonary epithelial cells transfected with Ad-elafin in vitro. In murine airways expression of human elafin was achieved using doses low enough (3 x 10(7) plaque forming units) to circumvent overt vector-induced inflammation. LPS significantly up-regulated human elafin secretion in murine airways treated with Ad-elafin [117 ng/ml in bronchoalveolar lavage fluid (BALF) after LPS administration, 5.9 ng/ml after PBS, p < 0.01)]. Over-expression of elafin significantly augmented LPS-mediated neutrophil migration into the airways in vivo (1.30 x 10(6) neutrophils in BALF after Ad-elafin/LPS treatment, 0.54 x 10(6) after Ad-lacZ/LPS (p < 0.05), 0.63 x 10(6) after PBS/LPS (p < 0.05)) and significantly enhanced human neutrophil migration in vitro. These data suggest novel functions for elafin in neutrophil migration, and that judicious selection of promoters may allow single, low-dose adenoviral administration to effect inflammation-specific expression of potentially therapeutic transgenes.     

Neutrophil modulation of the pulmonary chemokine response to lipopolysaccharide

When cells within the intrapulmonary compartment are exposed to pathogens or their products such as lipopolysaccharide, they produce CXC chemokines in order to attract circulating neutrophils into the lower respiratory tract. Previous studies have shown that as neutrophils (PMNs) enter the lung, bronchoalveolar lavage (BAL) chemokine levels are decreased. In this study, we determined the intrapulmonary and systemic responses to two important rat chemokines, cytokine-induced neutrophil chemoattractant (CINC) and macrophage inflammatory protein-2 (MIP-2), to intratracheal (i.t.) LPS (100 microg in 0.5 mL of phosphate-buffered saline) under neutropenic (cyclophosphamide [CPA]) and neutrophilic (G-CSF) conditions. By 4 h after i.t. LPS, CPA pretreatment decreased PMN recruitment 83% and G-CSF increased PMN recruitment 91% compared with recruitment into the lung in vehicle-pretreated rats (42.7 +/- 19.3 million PMNs). Neutropenic rats had increased CINC and MIP-2 concentrations in BAL fluid 4 h after i.t. LPS when compared with levels seen in vehicle controls (P < 0.05). In vitro LPS-stimulated chemokine production by alveolar macrophages obtained from CPA- and vehicle-pretreated animals did not differ. The increase in BAL fluid chemokine levels in neutropenic rats corresponded to increased chemotaxis of neutrophils to BAL fluid from CPA-pretreated rats as compared with the chemotaxis response of PMN to BAL fluid from vehicle-pretreated rats. In contrast, G-CSF enhancement of neutrophil recruitment decreased chemotactic activity of BAL fluid collected 4 h after i.t. LPS. These data show that as neutrophils are recruited into the lung, they alter chemokine levels, which most likely serves to down-regulate the inflammatory response.     

Effect of alpha-melanocyte stimulating hormone on the apoptosis of the vascular endothelial cell of the lung in two-hit acute respiratory distress syndrome in rat]

OBJECTIVE: To investigate the effect of alpha-melanocyte stimulating hormone (alpha-MSH) on the apoptosis of the vascular endothelial cells of the lung in acute respiratory distress syndrome (ARDS) reproduced with acute hemorrhagic shock followed by intratracheal lipopolysaccharide (LPS, two-hit model) in rat. METHODS: Ten male Sprague Dawley rats, weighing (33.7+/-2.5) g, were randomly divided into two groups (A and B) with 5 in each group. All rats were anesthesized and ventilated mechanically with fractional concentration of inspired oxygen(FiO(2)) of 0.5, breath rate 100 times/min, tidal volume(V(T)) 12 ml/kg and inspiratory/expiratory ratio (I/E) 1:15. The blood was withdrawn to induce hemorrhagic shock via the carotid artery until blood pressure reached (45+/-5) mm Hg (1 mm Hg=0.133 kPa), which was maintained for 1 hour, and the shed blood and Ringer's lactate in volume equal to the shed blood were reinfused in 2 hours for resuscitation. Afterwards, LPS was given via the tracheal (200 microg/kg, in 500 microl normal saline) to establish the ARDS model. Group A was ARDS control group, group B was alpha-MSH administration group. alpha-MSH was intravenously administrated simultaneously, 3 hours and 6 hours after LPS given, the dosage was 17 mg/kg at each time point. The rats were sacrificed at 9 hours after LPS challenge, and the lung tissue was examined with microscope and electron microscope to observe the pathological changes and apoptosis of the vascular endothelial cells. RESULTS: In ARDS control group, remarkable infiltration of inflammatory cells was found in the alveoli, and the apoptosis of the vascular endothelial cells had developed to late stage. In alpha-MSH treatment group, few inflammatory cells were found in the alveoli, and the apoptosis of the endothelial cells was still in an early stage. CONCLUSION: alpha-MSH could inhibit the apoptosis of the vascular endothelial cells of the lung in the two-hit ARDS in rats. Therefore, it might have a protective effect on the lung after hemorrhagic shock and endotoxin challenge.     

Increased susceptibility to LPS-induced endotoxin shock in secretory leukoprotease inhibitor (SLPI)-deficient mice

Secretory leukoprotease inhibitor (SLPI) protects tissue against the destructive action of neutrophil elastase at the site of inflammation. Recent studies on new functions of SLPI have demonstrated that SLPI may play a larger role in innate immunity than merely as a protease inhibitor. To clarify the functions of SLPI in bacterial infections, we generated SLPI-deficient mice (SLPI(-/-) mice) and analyzed their response to experimental endotoxin shock induced by lipopolysaccharide (LPS). SLPI(-/-) mice showed a higher mortality from endotoxin shock than did wild type mice. This may be explained in part by our observation that SLPI(-/-) macro-phages show higher interleukin 6 and high-mobility group (HMG)-1 production and nuclear factor kappaB activities after LPS treatment than do SLPI(+/+) macrophages. SLPI also affects B cell function. SLPI(-/-) B cells show more proliferation and IgM production after LPS treatment than SLPI(+/+) B cells. Our results suggest that SLPI attenuates excessive inflammatory responses and thus assures balanced functioning of innate immunity.     

Endogenously synthesized nitric oxide prevents endotoxin-induced glomerular thrombosis.

Escherichia coli endotoxin (LPS) can induce the clinical syndrome of septic shock and renal cortical necrosis and can stimulate nitric oxide (NO) production from macrophages, vascular smooth muscle, and glomerular mesangial cells in vitro. NO is an endogenous vasodilator, which also inhibits platelet aggregation and adhesion. We therefore sought to determine whether LPS would stimulate NO production in vivo and, if so, whether this NO would modulate endotoxin-induced glomerular thrombosis. The stable NO end-products, NO2 and NO3, were measured in serum and urine collections from rats during baseline and after injection of LPS, with or without substances that modulate NO synthesis. The urinary excretion of NO2/NO3 was 1,964 +/- 311 nm/8 h during the baseline and increased to 6,833 +/- 776 nm/8 h after a single intraperitoneal injection of 0.1 mg/kg LPS (P < 0.05). The serum concentration of NO2/NO3 also significantly increased after LPS injection. Both the urine and serum stimulation was significantly prevented by the NO synthesis inhibitor, Nw-nitro-L-arginine methyl ester (L-NAME). L-Arginine, given with LPS+L-NAME significantly restored the NO2/NO3 levels in the urine. Ex vivo incubation of tissues from rats treated with LPS demonstrated NO production by the aorta, whole kidney, and glomeruli, but not cortical tubules. Histological examination of kidneys from rats given either LPS or L-NAME alone revealed that 2 and 4.5% of the glomeruli contained capillary thrombosis, respectively. In contrast, rats given LPS+L-NAME developed thrombosis in 55% of glomeruli (P < 0.001), which was significantly prevented when L-arginine was given concomitantly. We conclude that LPS stimulates endogenous production of NO in vivo and that this NO is critical in preventing LPS-induced renal thrombosis.     

Innate immune response in Th1- and Th2-dominant mouse strains

C57BL/6 and BALB/c mice are prototypical Th1- and Th2-type mouse strains, respectively. In the present study, we attempted to characterize the innate immune response of macrophages from these mouse strains. Macrophages from C57BL/6 mice produced higher levels of tumor necrosis factor-alpha (TNF-alpha) and interleukin (IL)-12 than those from BALB/c mice after stimulation with macrophage-activating lipopeptide-2 (MALP-2, a synthetic TLR-2 ligand) or lipopolysaccharide (LPS, a TLR-4 ligand). The augmented IL-12 production by C57BL/6 macrophages increased interferon-gamma and, in contrast, decreased IL-13 production by CD4+ T cells. On stimulation with MALP-2 or LPS, C57BL/6 macrophages produced lysosomal enzyme and nitric oxide, effector molecules for bacterial killing, whereas BALB/c macrophages did not. Bactericidal activity of BALB/c macrophages was impaired relative to C57BL/6 macrophages when cells were infected with live bacteria in vitro. In a murine model of septic peritonitis induced by cecal ligation and puncture (CLP), BALB/c mice failed to facilitate bacterial clearance relative to C57BL/6 mice despite an augmented peritoneal leukocyte infiltration that was associated with increased peritoneal levels of cytokines/chemokines. BALB/c mice exhibited increased plasma and hepatic levels of cytokines/chemokines, resulting in an exaggerated systemic inflammation as determined by acute-phase proteins. Finally, BALB/c mice were vulnerable to CLP-induced lethality relative to C57BL/6 mice. Altogether, innate immune response of macrophages is different between these mouse strains, which may affect the development of Th1 and Th2 adaptive immunity in these strains. Reduced systemic inflammatory response in C57BL/6 mice that may result from an eminent local response appears to be beneficial during sepsis.