leupeptins and Sepsis

Sepsis is a potentially fatal systemic inflammatory response syndrome caused by infection. In this study, we evaluated the effects of MCP-induced protein 1 (MCPIP1), a recently discovered inflammation-related ribonuclease, on sepsis-induced acute lung injury (ALI) and investigated the underlying mechanisms. Cecal ligation puncture and lipopolysaccharide induction were performed on Sprague-Dawley rats and RAW264.7 cells, respectively, to establish sepsis-induced ALI models. The proteasome inhibitor MG132 used as an activator of MCPIP1 overexpression, and we showed that MG132 can indeed increase the expression of MCPIP1. MCPIP1 overexpression induced by MG132 alleviated sepsis-induced pathologic changes, water content and protein leakage in the lungs, and induction of systemic inflammatory mediators, and improved the 7-day mortality rate in the model rats. We also showed that MCPIP1 p showed romoted macrophage polarization from the M1 to the M2 type in sepsis-induced ALI. Furthermore, MCPIP1-enhanced M2 polarization was inhibited by an MCPIP1-targeting small interfering RNA (siMCPIP1) in RAW264.7 cells. Further mechanistic studies showed that the promotive effect of MCPIP1 on M2 polarization was related to the inhibition of c-Jun N-terminal kinase (JNK) and its downstream transcription factor c-Myc in the in vitro model. Conversely, siMCPIP1 transfection resulted in the recovery of JNK and c-Myc expression in LPS-treated cells. Taken together, these findings indicate that MCPIP1 plays a protective role in sepsis-induced ALI by modulating macrophage polarization through inhibition of the JNK/c-Myc signaling pathway. Our study presents a potentially novel therapeutic strategy for the treatment of lung injury involving the inflammatory cascade.

Topics: Acute Lung Injury; Animals; JNK Mitogen-Activated Protein Kinases; Leupeptins; Male; Mice; Proto-Oncogene Proteins c-myc; Rats, Sprague-Dawley; RAW 264.7 Cells; Ribonucleases; Sepsis; Signal Transduction

BACKGROUND The aim of the present study was to investigate the protective effects of protease inhibitor MG-132 on sepsis-induced acute lung injury rats. MATERIAL AND METHODS Sprague Dawley rats were employed to induce sepsis by cecal ligation and puncture (CLP) method. Rats were divided into 4 groups: control, sham, model (CLP), and MG-132. Histopathology observation was detected by hematoxylin and eosin staining. The ratio of wet lung to dry lung (W/D) was calculated. In addition, the levels of inflammatory factors in bronchoalveolar lavage fluid (BALF) were measured by enzyme-linked immunosorbent assay (ELISA). Also, superoxide dismutase (SOD) and malondialdehyde (MDA) levels were evaluated. Western blotting was performed to measure the expression of hypoxia-inducible factor-1 alpha (HIF-1alpha). In order to assess the role of HIF-1alpha, YC-1, the inhibitor of HIF-1alpha, was used to treat the rats. The expression of phosphor-mTOR (p-mTOR), p-4EBP1, and p-EIF4E were evaluated by western blotting. RESULTS Obvious pathological injury and increasing ratio of W/D in the model group were observed. Both pathological injury and W/D were improved in the MG-132 group, and the greatest improvement could be seen in the YC-1+MG-132 group. Furthermore, the MDA levels in the MG-132 group was decreased, accompanied by an increase in SOD levels. The level of HIF-1alpha was increased in the model group while a decreased was detected in the MG-132 group. The levels of inflammatory factors were high in the model group, whereas the opposite result was found in the MG-132 group, and the lowest in were in the YC-1+MG-132 group. Furthermore, the expression levels of p-mTOR, p-4EBP1, and p-EIF4E proteins were downregulated in the MG-132 group compared to the model group, and the lowest was in the YC-1+MG-132 group. CONCLUSIONS Our study suggested that MG-132 was able to protect against acute lung injury via inhibition of HIF-1alpha mediated mTOR/4EBP1/EIF4E pathway.

Topics: Acute Lung Injury; Animals; Bronchoalveolar Lavage Fluid; China; Eukaryotic Initiation Factor-4E; Hypoxia-Inducible Factor 1, alpha Subunit; Intracellular Signaling Peptides and Proteins; Leupeptins; Lung; Malondialdehyde; Pulmonary Edema; Rats; Rats, Sprague-Dawley; Sepsis; Superoxide Dismutase; TOR Serine-Threonine Kinases

Cardiac dysfunction caused by the impairment of myocardial contractility has been recognized as an important factor contributing to the high mortality in sepsis. Calpain activation in the heart takes place in response to increased intracellular calcium influx resulting in proteolysis of structural and contractile proteins with subsequent myocardial dysfunction. The purpose of the present study was to test the hypothesis that increased levels of calpain in the septic heart leads to disruption of structural and contractile proteins and that administration of calpain inhibitor-1 (N-acetyl-leucinyl-leucinyl-norleucinal (ALLN)) after sepsis induced by cecal ligation and puncture prevents cardiac protein degradation. We also tested the hypothesis that calpain plays a role in the modulation of protein synthesis/degradation through the activation of proteasome-dependent proteolysis and inhibition of the mTOR pathway. Severe sepsis significantly increased heart calpain-1 levels and promoted ubiquitin and Pa28β over-expression with a reduction in the mTOR levels. In addition, sepsis reduced the expression of structural proteins dystrophin and β-dystroglycan as well as the contractile proteins actin and myosin. ALLN administration prevented sepsis-induced increases in calpain and ubiquitin levels in the heart, which resulted in decreased of structural and contractile proteins degradation and basal mTOR expression levels were re-established. Our results support the concept that increased calpain concentrations may be part of an important mechanism of sepsis-induced cardiac muscle proteolysis.

Topics: Actins; Animals; Calpain; Cardiomyopathies; Disease Models, Animal; Dystrophin; Gene Expression; Leupeptins; Male; Mice; Mice, Inbred C57BL; Microscopy, Fluorescence; Myocardium; Myosins; Proteasome Endopeptidase Complex; Proteolysis; Sepsis; TOR Serine-Threonine Kinases; Ubiquitin

Lipopolysaccharide decreases intestinal contractility and induces the production of cytokines, which play an important role in the pathogenesis of sepsis.. The objective of the present study was to examine the role of Toll-like receptor 4, IκB kinase, and the proteasome in the intestinal alterations induced by lipopolysaccharide.. Sepsis was induced in rabbits by intravenous injection of lipopolysaccharide. Contractility studies of rabbit duodenum were performed in an organ bath. Expressions of interleukin-1β, interleukin-6, interleukin-8, interleukin-10, IκB kinase-α, IκB kinase-β, IκB kinase-γ, and the proteasome mRNA were determined by RT-PCR on rabbit duodenum.. Neomycin and polymyxin B (Toll-like receptor 4 inhibitors), IKK NBD peptide (IκB kinase complex inhibitor), and MG-132 (proteasome inhibitor) blocked partially the effects of lipopolysaccharide on the acetylcholine-, prostaglandin E2-, substance P-, and KCl-induced contractions in the longitudinal and circular smooth muscle of rabbit duodenum. Lipopolysaccharide increased the mRNA expression of interleukin-6 and interleukin-8 in duodenal tissue, and this effect was partly reversed by neomycin, polymyxin B, IKK NBD peptide, and MG-132. IκB kinase-α, IκB kinase-β, IκB kinase-γ, and the proteasome mRNA expressions was not affected by lipopolysaccharide treatment.. Toll-like receptor 4, the IκB kinase complex, and the proteasome could be therapeutic targets in the treatment of sepsis symptoms in the intestine.

Topics: Acetylcholine; Animals; Cell-Penetrating Peptides; Cytokines; Dinoprostone; Disease Models, Animal; Duodenum; Endotoxins; Gastrointestinal Motility; Gene Expression Regulation; I-kappa B Kinase; Inflammation Mediators; Leupeptins; Male; Muscle Contraction; Neomycin; Polymyxin B; Potassium Chloride; Proteasome Endopeptidase Complex; Proteasome Inhibitors; Protein Kinase Inhibitors; Rabbits; Sepsis; Signal Transduction; Substance P; Toll-Like Receptor 4

Infections produce severe respiratory muscle dysfunction. It is known that the proteasome proteolytic system is activated in skeletal muscle in sepsis, and it has been postulated that this degradative pathway is responsible for inducing skeletal muscle weakness and wasting. The objective of this study was to determine if administration of proteasomal inhibitors (MG132, epoxomicin, bortezomib) can prevent sepsis-induced diaphragm weakness. Rats were given either 1) saline (0.5 ml ip), 2) endotoxin (12 mg/kg ip), 3) endotoxin plus MG132 (2.5 mg/kg), 4) endotoxin plus epoxomicin (1 micromol/kg), or 5) endotoxin plus bortezomib (0.05 mg/kg). Animals were killed either 48 or 96 h after injections, and assessments were made of diaphragm proteolysis, force-frequency relationships, mass, protein content, and caspase activation. Endotoxin increased proteolysis (P <0.001). MG132, epoxomicin, and bortezomib each prevented the endotoxin-induced increase in proteolysis (P <0.01). Endotoxin induced severe reductions in diaphragm force generation by 48 h (P <0.01); none of the proteasomal inhibitors prevented loss of force. Endotoxin induced significant reductions in diaphragm mass and protein content by 96 h (P <0.01); neither MG132 nor epoxomicin prevented loss of mass or protein, but bortezomib attenuated the reduction in protein content (P <0.05). Endotoxin increased diaphragm caspase-3 activity (P <0.01); caspase-3 activity remained high when either MG132, epoxomicin, or bortezomib were given. These data suggest proteasomal inhibitors are not an adequate treatment to prevent endotoxin-induced diaphragmatic dysfunction.

Topics: Animals; Atrophy; Boronic Acids; Bortezomib; Caspase 3; Cysteine Proteinase Inhibitors; Diaphragm; Endotoxemia; Enzyme Activation; Leupeptins; Male; Muscle Contraction; Muscle Weakness; Oligopeptides; Organ Size; Protease Inhibitors; Proteasome Endopeptidase Complex; Proteasome Inhibitors; Pyrazines; Rats; Rats, Sprague-Dawley; Sepsis; Tyrosine

The Ubiquitin-proteasome system has recently been shown to be involved in the regulation of cytokine expression. We tested the hypothesis of whether the in vivo administration of proteasome inhibitor MG-132 can modulate cytokine response and mortality in sepsis. Sepsis was induced in mice by caecal ligation and puncture (CLP). Animals were divided into four groups: control, CLP, CLP and 1 microg MG-132/g of b.w. intraperitoneally, and CLP and 10 microg MG-132/g of b.w. Plasma levels of interleukin (IL)-1, tumour necrosis factor-alpha (TNF-alpha, IL-6 and IL-10 were determined by ELISA 6 h after the induction of sepsis. CLP induced significant increase in plasma levels of all measured cytokines. MG-132 treatment resulted in lower increase in IL-1, TNF-alpha and IL-10 levels. IL-6 was not significantly affected. A mortality study revealed prolonged survival in MG-132 treated mice. We conclude that MG-132 treatment decreases inflammatory response and prolongs survival in the CLP model of sepsis.

Topics: Animals; Cysteine Proteinase Inhibitors; Cytokines; Dose-Response Relationship, Drug; Female; Inflammation Mediators; Leupeptins; Mice; Mice, Inbred C57BL; Proteasome Inhibitors; Sepsis; Survival Analysis

To study the effect of ubiquitin-proteasome pathway inhibition on intestinal nuclear factor-KappaB (NF-KappaB) activity and tumor necrosis factor-alpha (TNF-alpha) release as well as plasma diamine oxidase (DAO) activity in rats with postburn sepsis.. Rats were subjected to 30% total body surface area (TBSA) full-thickness scald injury, followed by intraperitoneal injection of lipopolysaccharide (LPS) to mimic postburn sepsis. Sixty Wistar rats were randomly divided into normal control group, sepsis group, sepsis with proteasome inhibitor N-Acetyl leucinyl leucinyl norleucinal (ALLN) treatment group and sepsis with NF-KappaB inhibitor pyrrolidine dithiocarbamate (PDTC) treatment group. NF-KappaB activity, TNF-alpha protein content, and plasma DAO activity were determined by electrophoretic mobility shift assay (EMSA), enzyme-linked immunosorbent assay (ELISA), and spectrophotometric method, respectively.. The results showed that NF-KappaB activity was markedly activated and reached its peak 1 hour after scalding and injection of LPS in each group (all P<0.01), then reduced gradually. Both ALLN and PDTC could decrease intestinal NF-KappaB activity at 1 hour and 2 hours after injury. TNF-alpha release was reduced by ALLN at 1 hour after injury (P<0.01). Plasma DAO activity was significantly elevated after scalding and injection of LPS (P<0.01). Pretreatment with PDTC or ALLN could not lower the activity of DAO.. The results suggest that early treatment with inhibitor of ubiquitin-proteasome pathway might decrease the intestinal inflammatory reaction, but exert no effect on intestinal barrier function in rats with postburn sepsis.

Topics: Amine Oxidase (Copper-Containing); Animals; Burns; Cysteine Proteinase Inhibitors; Disease Models, Animal; Intestinal Mucosa; Intestines; Leupeptins; Male; NF-kappa B; Proteasome Endopeptidase Complex; Proteasome Inhibitors; Pyrrolidines; Random Allocation; Rats; Rats, Wistar; Sepsis; Thiocarbamates; Tumor Necrosis Factor-alpha; Ubiquitin

Cardiac myocytes isolated from rats with peritonitis (cecal ligation and perforation; CLP) promote PMN transendothelial migration. Herein, we assessed (1) the mechanisms involved in cardiac myocyte activation during peritonitis and (2) the means by which these activated myocytes promote PMN transendothelial migration. Plasma obtained from mice subjected to CLP (septic plasma) activated isolated cardiac myocytes as evidenced by (1) increased nuclear levels of nuclear factor-kappaB (NF-kappaB) and (2) their ability to promote PMN migration across endothelial cell monolayers. Pretreatment of septic plasma with an antibody against tumor necrosis factor-alpha (TNF-alpha), but not interleukin-1beta (IL-1beta), blunted the ability of septic plasma to activate the myocytes. However, septic plasma obtained from TNF-alpha-deficient mice could still activate the myocytes; an effect attenuated by an antibody against IL-1beta. If the myocytes were pretreated with a proteasome inhibitor (MG 132) to prevent NF-kappaB activation, the myocyte-induced PMN transendothelial migration was compromised. The activated myocytes released platelet-activating factor (PAF), and myocyte-induced PMN migration was abrogated by a PAF receptor antagonist (WEB 2086). These myocytes also released the CXC chemokines LIX and KC; an event prevented by MG 132. Antibodies against LIX and KC abrogated the myocyte-induced PMN migration. However, LIX and KC, but not PAF, could promote PMN migration when used at concentrations produced by activated myocytes. These observations indicate that TNF-alpha and IL-1beta are, in part, responsible for the ability of septic plasma to activate cardiac myocytes. The activated myocytes promote PMN transendothelial migration, an effect attributable to LIX and KC, and possibly, PAF.

Topics: Animals; Animals, Newborn; Azepines; Cecum; Chemokine CXCL1; Chemokine CXCL5; Chemokines, CXC; Chemotaxis, Leukocyte; Cysteine Endopeptidases; Disease Models, Animal; Endothelium, Vascular; Intercellular Signaling Peptides and Proteins; Interleukin-1; Intestinal Perforation; Leupeptins; Ligation; Mice; Mice, Inbred C57BL; Mice, Knockout; Multienzyme Complexes; Myocytes, Cardiac; Neutrophils; NF-kappa B; Peritonitis; Plasma; Protease Inhibitors; Proteasome Endopeptidase Complex; Sepsis; Triazoles; Tumor Necrosis Factor-alpha

Proteasome inhibitors are novel therapeutic agents for the treatment of cancer and other severe disorders. One of the possible side effects is influencing the metabolism of proteins. The aim of our study was to evaluate the influence of three proteasome inhibitors MG132, ZL(3)VS and AdaAhx(3)L(3)VS on protein metabolism and leucine oxidation in incubated skeletal muscle of control and septic rats. Total proteolysis was determined according to the rates of tyrosine release into the medium during incubation. The rates of protein synthesis and leucine oxidation were measured in a medium containing L-[1-(14)C]leucine. Protein synthesis was determined as the amount of L-[1-(14)C]leucine incorporated into proteins, and leucine oxidation was evaluated according to the release of (14)CO(2) during incubation. Sepsis was induced in rats by means of caecal ligation and puncture. MG132 reduced proteolysis by more than 50% and protein synthesis by 10-20% in the muscles of healthy rats. In septic rats, proteasome inhibitors, except ZL(3)VS, decreased proteolysis in both soleus and extensor digitorum longus (EDL) muscles, although none of the inhibitors had any effect on protein synthesis. Leucine oxidation was increased by AdaAhx(3)L(3)VS in the septic EDL muscle and decreased by MG132 in intact EDL muscle. We conclude that MG132 and AdaAhx(3)L(3)VS reversed protein catabolism in septic rat muscles.

Topics: Animals; Cysteine Proteinase Inhibitors; Kidney; Leucine; Leupeptins; Liver; Male; Muscle, Skeletal; Oligopeptides; Oxidation-Reduction; Proteasome Inhibitors; Proteins; Rats; Rats, Wistar; Sepsis; Spleen

Recent studies suggest that sepsis stimulates ubiquitin-dependent protein breakdown in skeletal muscle. The 20S proteasome is the catalytic core of the ubiquitin-dependent proteolytic pathway. We tested the effects in vitro of the proteasome inhibitors N-acetyl-L-leucinyl-L-leucinal-L-norleucinal (LLnL) and lactacystin on protein breakdown in incubated muscles from septic rats. LLnL resulted in a dose- and time-dependent inhibition of protein breakdown in muscles from septic rats. Lactacystin blocked both total and myofibrillar muscle protein breakdown. In addition to inhibiting protein breakdown, LLnL reduced muscle protein synthesis and increased ubiquitin mRNA levels, probably reflecting inhibited proteasome-associated ribonuclease activity. Inhibited muscle protein breakdown caused by LLnL or lactacystin supports the concept that the ubiquitin-proteasome pathway plays a central role in sepsis-induced muscle proteolysis. The results suggest that muscle catabolism during sepsis may be inhibited by targeting specific molecular mechanisms of muscle proteolysis.

Topics: Acetylcysteine; Animals; Cecum; Cysteine Endopeptidases; Cysteine Proteinase Inhibitors; Dactinomycin; Kinetics; Leupeptins; Male; Multienzyme Complexes; Muscle Proteins; Muscle, Skeletal; Proteasome Endopeptidase Complex; Rats; Rats, Sprague-Dawley; RNA, Messenger; Sepsis; Transcription, Genetic; Ubiquitins

The effects of N-acetyl-leucinyl-leucinyl-norleucinal (ALLN), a potent inhibitor of proteolysis catalyzed by proteasomes, on the activation of NF-kappaB in vitro and in vivo have been examined. Confirming earlier observations, ALLN inhibits the activation of NF-kappaB in macrophage cultures stimulated with LPS, resulting in the intracellular accumulation of IkappaB and p105. The synthesis of TNF, a reaction dependent upon NF-kappaB activation, is blocked by ALLN. Treatment of mice with LPS results in the induction of TNF and IL-6 within 90 min followed by lethal shock at 24 hr. In mice pretreated with ALLN, serum TNF and IL-6 levels were significantly lower than those in untreated animals. These studies suggest that the proteasome is a novel target for the identification of agents that may be useful in the treatment of those diseases whose etiology is dependent on the activation of NF-kappaB.

Topics: Animals; Cells, Cultured; Feasibility Studies; Female; Gene Expression Regulation; Interleukin-6; Leupeptins; Lipopolysaccharides; Macrophages; Mice; NF-kappa B; Sepsis; Tumor Necrosis Factor-alpha