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Protein-disulfide isomerase (PDI) is a ubiquitous dithiol–disulfide oxidoreductase that performs an array of cellular functions, such as cellular signaling and responses to cell-damaging events. PDI can become dysfunctional by post-translational modifications, including those promoted by biological oxidants, and its dysfunction has been associated with several diseases in which oxidative stress plays a role. Because the kinetics and products of the reaction of these oxidants with PDI remain incompletely characterized, we investigated the reaction of PDI with the biological oxidant peroxynitrite. First, by determining the rate constant of the oxidation of PDI's redox-active Cys residues (Cys53 and Cys397) by hydrogen peroxide (k = 17.3 ± 1.3 m−1 s−1 at pH 7.4 and 25 °C), we established that the measured decay of the intrinsic PDI fluorescence is appropriate for kinetic studies. The reaction of these PDI residues with peroxynitrite was considerably faster (k = (6.9 ± 0.2) × 104 m−1 s−1), and both Cys residues were kinetically indistinguishable. Limited proteolysis, kinetic simulations, and MS analyses confirmed that peroxynitrite preferentially oxidizes the redox-active Cys residues of PDI to the corresponding sulfenic acids, which reacted with the resolving thiols at the active sites to produce disulfides (i.e. Cys53–Cys56 and Cys397–Cys400). A fraction of peroxynitrite, however, decayed to radicals that hydroxylated and nitrated other active-site residues (Trp52, Trp396, and Tyr393). Excess peroxynitrite promoted further PDI oxidation, nitration, inactivation, and covalent oligomerization. We conclude that these PDI modifications may contribute to the pathogenic mechanism of several diseases associated with dysfunctional PDI.

Protein disulfide isomerases are thiol oxidoreductase chaperones from thioredoxin superfamily. As redox folding catalysts from the endoplasmic reticulum (ER), their roles in ER-related redox homeostasis and signaling are well-studied. PDIA1 exerts thiol oxidation/reduction and isomerization, plus chaperone effects. Also, substantial evidence indicates that PDIs regulate thiol-disulfide switches in other cell locations such as cell surface and possibly cytosol. Subcellular PDI translocation routes remain unclear and seem Golgi-independent. The list of signaling and structural proteins reportedly regulated by PDIs keeps growing, via thiol switches involving oxidation, reduction and isomerization, S-(de)nytrosylation, (de)glutathyonylation and protein oligomerization. PDIA1 is required for agonist-triggered Nox NADPH oxidase activation and cell migration in vascular cells and macrophages, while PDIA1-dependent cytoskeletal regulation appears a converging pathway. Extracellularly, PDIs crucially regulate thiol redox signaling of thrombosis/platelet activation, e.g., integrins, and PDIA1 supports expansive caliber remodeling during injury repair via matrix/cytoskeletal organization. Some proteins display regulatory PDI-like motifs. PDI effects are orchestrated by expression levels or post-translational modifications. PDI is redox-sensitive, although probably not a mass-effect redox sensor due to kinetic constraints. Rather, the “all-in-one” organization of its peculiar redox/chaperone properties likely provide PDIs with precision and versatility in redox signaling, making them promising therapeutic targets.

BackgroundProtein Disulfide Isomerases are thiol oxidoreductase chaperones from thioredoxin superfamily with crucial roles in endoplasmic reticulum proteostasis, implicated in many diseases. The family prototype PDIA1 is also involved in vascular redox cell signaling. PDIA1 is coded by theP4HBgene. While forced changes inP4HBgene expression promote physiological effects, little is known about endogenousP4HBgene regulation and, in particular, gene modulation by alternative splicing. This study addressed theP4HBsplice variant landscape.ResultsTen protein coding sequences (Ensembl) of theP4HBgene originating from alternative splicing were characterized. Structural features suggest that except forP4HB-021, other splice variants are unlikely to exert thiol isomerase activity at the endoplasmic reticulum. Extensive analyses using FANTOM5, ENCODE Consortium and GTEx project databases as RNA-seq data sources were performed. These indicated widespread expression but significant variability in the degree of isoform expression among distinct tissues and even among distinct locations of the same cell, e.g., vascular smooth muscle cells from different origins.P4HB-02,P4HB-027 andP4HB-021 were relatively more expressed across each database, the latter particularly in vascular smooth muscle. Expression of such variants was validated by qRT-PCR in some cell types. The most consistently expressed splice variant wasP4HB-021 in human mammary artery vascular smooth muscle which, together with canonicalP4HBgene, had its expression enhanced by serum starvation.ConclusionsOur study details the splice variant landscape of theP4HBgene, indicating their potential role to diversify the functional reach of this crucial gene.P4HB-021 splice variant deserves further investigation in vascular smooth muscle cells.

Background Extracellular surface protein disulfide isomerase-A1 (PDI) is involved in platelet aggregation, thrombus formation and vascular remodeling. PDI performs redox exchange with client proteins and, hence, its oxidation by extracellular molecules might alter protein function and cell response. In this study, we investigated PDI oxidation by urate hydroperoxide, a newly-described oxidant that is generated through uric acid oxidation by peroxidases, with a putative role in vascular inflammation. Methods Amino acids specificity and kinetics of PDI oxidation by urate hydroperoxide was evaluated by LC-MS/MS and by stopped-flow. Oxidation of cell surface PDI and other thiol-proteins from HUVECs was identified using impermeable alkylating reagents. Oxidation of intracellular GSH and GSSG was evaluated with specific LC-MS/MS techniques. Cell adherence, detachment and viability were assessed using crystal violet staining, cellular microscopy and LDH activity, respectively. Results Urate hydroperoxide specifically oxidized cysteine residues from catalytic sites of recombinant PDI with a rate constant of 6 × 103 M−1 s−1. Incubation of HUVECs with urate hydroperoxide led to oxidation of cell surface PDI and other unidentified cell surface thiol-proteins. Cell adherence to fibronectin coated plates was impaired by urate hydroperoxide, as well as by other oxidants, thiol alkylating agents and PDI inhibitors. Urate hydroperoxide did not affect cell viability but significantly decreased GSH/GSSG ratio. Conclusions Our results demonstrated that urate hydroperoxide affects thiol-oxidation of PDI and other cell surface proteins, impairing cellular adherence. General significance These findings could contribute to a better understanding of the mechanism by which uric acid affects endothelial cell function and vascular homeostasis.

Redox-related plasma proteins are candidate reporters of protein signatures associated with endothelial structure/function. Thiol-proteins from protein disulfide isomerase (PDI) family are unexplored in this context. Here, we investigate the occurrence and physiological significance of a circulating pool of PDI in healthy humans. We validated an assay for detecting PDI in plasma of healthy individuals. Our results indicate high inter-individual (median = 330 pg/mL) but low intra-individual variability over time and repeated measurements. Remarkably, plasma PDI levels could discriminate between distinct plasma proteome signatures, with PDI-rich (>median) plasma differentially expressing proteins related to cell differentiation, protein processing, housekeeping functions and others, while PDI-poor plasma differentially displayed proteins associated with coagulation, inflammatory responses and immunoactivation. Platelet function was similar among individuals with PDI-rich vs. PDI-poor plasma. Remarkably, such protein signatures closely correlated with endothelial function and phenotype, since cultured endothelial cells incubated with PDI-poor or PDI-rich plasma recapitulated gene expression and secretome patterns in line with their corresponding plasma signatures. Furthermore, such signatures translated into functional responses, with PDI-poor plasma promoting impairment of endothelial adhesion to fibronectin and a disturbed pattern of wound-associated migration and recovery area. Patients with cardiovascular events had lower PDI levels vs. healthy individuals. This is the first study describing PDI levels as reporters of specific plasma proteome signatures directly promoting contrasting endothelial phenotypes and functional responses., Graphical abstract Image 1, Highlights • A newly-validated plasma PDI assay shows high inter- but low intra-individual variability. • PDI-poor plasma carries protein signatures related to coagulation/immunoinflammation • PDI-rich plasma protein signatures relate to cell adhesion/housekeeping functions. • Endothelial exposure to such plasmas triggers corresponding gene and secretome patterns. • PDI-poor plasma impairs endothelial adhesion and migration vs. PDI-rich plasma.

Objective: The purpose of this study was to evaluate the in vivo response of two different laser fluences (4 and 8 J/cm2) on molecular markers involved in muscle repair after a cryolesion of the tibialis anterior (TA) muscle. Study design: Forty-eight male Wistar rats were randomly distributed into six groups: control (C); normal/uninjured TA muscle treated with either 4 J/cm2 (L4J) or 8 J/cm2 (L8J) laser irradiation; injured TA muscle without treatment (IC); and injured TA muscle treated with either 4 J/cm2 (IL4J) or 8 J/cm2 (IL8J) laser irradiation. The injured region was irradiated daily for 5 consecutive days, starting immediately after the cryolesion was set using a GaAlAs laser (continuous wave; wavelength, 830 nm; tip area, 0.0028 cm2; power, 20 mW). The animals were euthanized on the sixth day after injury. The injured right TA muscles were removed for histological evaluation, zymography, and immunoblotting and biotin switch analyses. Nitrite and nitrate plasma levels were measured to evaluate the nitric oxide (NO) production. Results: After low-level laser therapy (LLLT), in both injured treatment groups (IL4J and IL8J) the injured area was reduced, the NO production decreased and the S-nitrosated COX-2 was lowered. Moreover, both laser fluences increased the activity and expression of MMP-2. Conclusion: These results suggest that LLLT, for both fluences, could be an efficient therapeutic approach to modulate molecules involved in injured muscle, accelerating regeneration process.

The mechanisms by which exercise affects atherosclerotic plaque stability remain incompletely understood. We evaluated the effects of two training protocols on both atherosclerotic plaque structure and the signaling pathways involved in plaque rupture. Methods Male low-density lipoprotein (LDL) receptor knockout mice were fed a high-fat, high-cholesterol diet (HFD). One group was subjected to moderate exercise using a treadmill for 14 weeks (preventive protocol). The other group started an exercise regimen after 16 weeks of the HFD (therapeutic group). Atherosclerotic plaques within the aorta were evaluated for lipid and collagen contents, as well as for inflammatory markers. Plasma cholesterol and cytokine levels were also determined. Results The mice receiving a HFD developed hypercholesterolemia and atherosclerotic plaques within the aorta. The aortas from the animals in the preventive protocol exhibited smaller lipid cores and higher collagen content. These animals also exhibited lower CD40 expression within the plaques. The aortas of the mice in the therapeutic group exhibited higher collagen content, but no differences in either lipid core size or plaque size were noted. No differences in blood pressure, plasma cholesterol, cytokine levels, plaque size or metalloproteinase 9 expression were observed in the trained animals compared with the sedentary animals. Conclusion Moderate aerobic exercise modified atherosclerotic plaque characteristics and converted the plaques into a more stable phenotype, increasing the collagen content in response to both exercise programs. Furthermore, moderate aerobic exercise reduced the animals' fat content and decreased the activity of the CD40–CD40L signaling pathway in the preventive group.

Protein disulfide isomerases including PDIA1 are implicated in cancer progression, but underlying mechanisms are unclear. PDIA1 is known to support vascular Nox1 NADPH oxidase expression/activation. Since deregulated reactive oxygen species (ROS) production underlies tumor growth, we proposed that PDIA1 is an upstream regulator of tumor-associated ROS. We focused on colorectal cancer (CRC) with distinct KRas activation levels. Analysis of RNAseq databanks and direct validation indicated enhanced PDIA1 expression in CRC with constitutive high (HCT116) vs. moderate (HKE3) and basal (Caco2) Ras activity. PDIA1 supported Nox1-dependent superoxide production in CRC; however, we first reported a dual effect correlated with Ras-level activity: in Caco2 and HKE3 cells, loss-of-function experiments indicate that PDIA1 sustains Nox1-dependent superoxide production, while in HCT116 cells PDIA1 restricted superoxide production, a behavior associated with increased Rac1 expression/activity. Transfection of Rac1G12V active mutant into HKE3 cells induced PDIA1 to become restrictive of Nox1-dependent superoxide, while in HCT116 cells treated with Rac1 inhibitor, PDIA1 became supportive of superoxide. PDIA1 silencing promoted diminished cell proliferation and migration in HKE3, not detectable in HCT116 cells. Screening of cell signaling routes affected by PDIA1 silencing highlighted GSK3β and Stat3. Also, E-cadherin expression after PDIA1 silencing was decreased in HCT116, consistent with PDIA1 support of epithelial–mesenchymal transition. Thus, Ras overactivation switches the pattern of PDIA1-dependent Rac1/Nox1 regulation, so that Ras-induced PDIA1 bypass can directly activate Rac1. PDIA1 may be a crucial regulator of redox-dependent adaptive processes related to cancer progression.

Cancer development is closely related to chronic inflammation, which is associated with identifiable markers of tumor progression, such as uncontrolled cell proliferation, angiogenesis, genomic instability, chemotherapeutic resistance, and metastases. Redox processes mediated by reactive oxygen species (ROS) and nitric oxide (NO) within the inflammatory tumor microenvironment play an essential role in directly influencing intercellular and intracellular signaling. These reactive species originating in the cancer cell or its microenvironment, mediate the epithelial-mesenchymal transition (EMT) and the mesenchymal-epithelial transition (MET). However, intracellular interactions between NO and ROS must be controlled to prevent cell death. Melanoma, breast, and colon cancer cells have developed a mechanism to survive and adapt to oxidative and nitrosative stress. The mechanism involves a spatial-temporal fine adjustment of the intracellular concentrations of NO and ROS, thereby guaranteeing the successful development of cancer cells. Physiological concentrations of NO and supra physiological concentrations of ROS are prevalent in cancer cells at the primary site. The situation reverses in cancer cells undergoing the EMT prior to being released into the blood stream. Intracellular supra physiological concentrations of NO found in circulating cancer cells endow them with anoikis resistance. When the anoikis-resistant cancer cells arrive at a metastatic site they undergo the MET. Endogenous supra physiological concentrations of ROS and physiological NO concentrations are prevalent in these cells. Understanding tumor progression from the perspective of redox signaling permits the characterization of new markers and approaches to therapy. The synthesis and use of compounds with the capacity of modifying intracellular concentrations of NO and ROS may prove effective in disrupting a redox homeostasis operative in cancer cells.

Heat shock protein-70 (HSP70) is crucial for proteostasis and displays cell-protective effects. Meanwhile, enhanced levels of cell-surface (cs) and secreted HSP70 paradoxically associate with pathologic cardiovascular conditions. However, mechanisms regulating csHSP70 pool are unknown. We hypothesized that total and csHSP70 expressions are modulated by hemodynamic forces, major contributors to endothelial pathophysiology. We also investigated whether thrombomodulin, a crucial thromboresistance cell-surface protein, is a csHSP70 target. We used proteomic/western analysis, confocal microscopy, and cs-biotinylation to analyze the pattern and specific characteristics of intracellular and csHSP70. HSP70 interaction with thrombomodulin was investigated by confocal colocalization, en face immunofluorescence, proximity assay, and immunoprecipitation. Thrombomodulin activity was assessed by measured protein C activation two-step assay. Our results show that csHSP70 pool in endothelial cells (EC) exhibits a peculiar cluster-like pattern and undergoes enhanced expression by physiological arterial-level laminar shear stress. Conversely, total and csHSP70 expressions were diminished under low shear stress, a known proatherogenic hemodynamic pattern. Furthermore, total HSP70 levels were decreased in aortic arch (associated with proatherogenic turbulent flow) compared with thoracic aorta (associated with atheroprotective laminar flow). Importantly, csHSP70 co-localized with thrombomodulin in cultured EC and aorta endothelium; proximity ligation assays and immunoprecipitation confirmed their physical interaction in EC. Remarkably, immunoneutralization of csHSP70 enhanced thrombomodulin activity in EC and aorta ex vivo. Overall, proatherogenic hemodynamic forces promote reduced total HSP70 expression, which might implicate in disturbed proteostasis; meanwhile, the associated decrease in cs-HSP70 pool associates with thromboresistance signaling. Cell-surface HSP70 (csHSP70) expression regulation and csHSP70 targets in vascular cells are unknown. We showed that HSP70 levels are shear stress-modulated and decreased under proatherogenic conditions. Remarkably, csHSP70 binds thrombomodulin and inhibits its activity in endothelial cells. This mechanism can potentially explain some deleterious effects previously associated with high extracellular HSP70 levels, as csHSP70 potentially could restrict thromboresistance and support thrombosis/inflammation in stress situations.

Fibrillin-1 mutations promote Marfan syndrome (MFS) via complex yet unclear pathways. The roles of endoplasmic reticulum (ER) and the major ER redox chaperone protein disulfide isomerase-A1 in the processing of normal and mutated fibrillin-1 and ensuing protein secretion and/or intracellular retention are unclear. Our results in mouse embryonic fibroblasts bearing the exon-skipping mgΔ(lox-P-neo) (mgΔ(lpn)) mutation, which associates in vivo with MFS and in vitro with disrupted microfibrils, indicate a preserved ER-dependent proteostasis or redox homeostasis. Rather, mutated fibrillin-1 is secreted normally through Golgi-dependent pathways and is not intracellularly retained. Similar results occurred for the C1039G point mutation. In parallel, we provide evidence that PDIA1 physically interacts with fibrillin-1 in the ER. Moreover, siRNA against PDIA1 augmented fibrillin-1 secretion rates in wild-type cells. However, fibrillin-1 with the mgΔ(lpn) mutation bypassed PDI checkpoint delay, while the C1039G mutation did not. This heretofore undisclosed PDIA1-mediated mechanism may be important to control the extracellular availability of function-competent fibrillin-1, an important determinant of disease phenotype. Moreover, our results may reveal a novel, holdase-like, PDI function associated with ER protein quality control.

Previous studies from our group have demonstrated the protective effect of S-nitroso-N-acetylcysteine (SNAC) on the cardiovascular system in dyslipidemic LDLr−/− mice that develop atheroma and left ventricular hypertrophy after 15days on a high fat diet. We have shown that SNAC treatment attenuates plaque development via the suppression of vascular oxidative stress and protects the heart from structural and functional myocardial alterations, such as heart arrhythmia, by reducing cardiomyocyte sensitivity to catecholamines. Here we investigate the ability of SNAC to modulate oxidative stress and cell survival in cardiomyocytes during remodeling and correlation with β2-AR signaling in mediating this protection. Ventricular superoxide (O2-) and hydrogen peroxide (H2O2) generation was measured by HPLC methods to allow quantification of dihydroethidium (DHE) products. Ventricular histological sections were stained using terminal dUTP nick-end labeling (TUNEL) to identify nuclei with DNA degradation (apoptosis) and this was confirmed by Western blot for cleaved caspase-3 and caspase-7 protein expression. The findings show that O2- and H2O2 production and also cell apoptosis were increased during left ventricular hypertrophy (LVH). SNAC treatment reduced oxidative stress during on cardiac remodeling, measured by decreased H2O2 and O2- production (65% and 52%, respectively), and a decrease in the ratio of p-Ser1177 eNOS/total eNOS. Left ventricle (LV) from SNAC-treated mice revealed a 4-fold increase in β2-AR expression associated with coupling change to Gi; β2-ARs-S-nitrosation (β2-AR-SNO) increased 61%, while apoptosis decreased by 70%. These results suggest that the cardio-protective effect of SNAC treatment is primarily through its anti-oxidant role and is associated with β2-ARs overexpression and β2-AR-SNO via an anti-apoptotic pathway.

PURPOSE: To investigate if the ethyl-pyruvate solution could reduce mortality in AP and/or diminish the acute lung injury. METHODS: Forty male rats, weighing between 270 to 330 grams were operated. An experimental model of severe AP by injection of 0.1ml/100g of 2.5% sodium taurocholate into the bilio-pancreatic duct was utilized. The rats were divided into two groups of ten animals each: CT - control (treatment with 50ml/kg of Ringer's solution, intraperitoneal) and EP (treatment with 50ml/kg of Ringer ethyl- pyruvate solution, intra-peritoneal), three hours following AP induction. After six hours, a new infusion of the treatment solution was performed in each group. Two hours later, the animals were killed and the pulmonary parenchyma was resected for biomolecular analysis, consisting of: interleukin, myeloperoxidase, MDA, nitric oxide, metalloproteinases and heat shock protein. In the second part of the experiment, another, 20 rats were randomly divided into EP and CT groups, in order to evaluate a survival comparison between the two groups. RESULTS: There were no significant differences in IL-1B,IL-10, MMP-9, HSP70, nitric oxide, MPO, MDA (lipidic peroxidation) concerning both groups. The levels of IL-6 were significantly diminished in the EP group. Furthermore, the MMP-2 levels were also reduced in the EP group (p

Background and Objective Muscle regeneration is a complex phenomenon, involving coordinated activation of several cellular responses. During this process, oxidative stress and consequent tissue damage occur with a severity that may depend on the intensity and duration of the inflammatory response. Among the therapeutic approaches to attenuate inflammation and increase tissue repair, low-level laser therapy (LLLT) may be a safe and effective clinical procedure. The aim of this study was to evaluate the effects of LLLT on oxidative/nitrative stress and inflammatory mediators produced during a cryolesion of the tibialis anterior (TA) muscle in rats.

Objective Liver failure can occur as a consequence of the systemic inflammation after acute pancreatitis. We assessed the effect of volume repositioning with hypertonic saline solution or normal saline on hepatic cytokine production and the expression of heat-shock proteins and apoptotic proteins after acute pancreatitis. Methods Wistar rats were divided in four groups: C - control animals that were not subjected to insult or treatment; NT - animals that were subjected to acute pancreatitis and received no treatment; normal saline - animals that were subjected to acute pancreatitis and received normal saline (NaCl 0.9%); and HS - animals that were subjected to acute pancreatitis and received hypertonic saline solution (NaCl 7.5%). Acute pancreatitis was induced by retrograde transduodenal infusion of 2.5% sodium taurocholate into the pancreatic duct. At 4, 12 and 24 h following acute pancreatitis induction, TNF-alpha, IL-1-beta, IL-6 and IL-10, caspase-2 and -7, Apaf-1, AIF and HSP60 and 90 were analyzed in the liver. Results Casp2 decreased in the normal saline and hypertonic saline groups (p

Received 21 Jun 2011; first review completed 28 Jun 2011; accepted in final form 11 Aug 2011ABSTRACT—Sepsis and septic shock are associated with cardiac depression. Cardiovascular instability is a major causeof death in patients with sepsis. Focal adhesion kinase (FAK) is a potential mediator of cardiomyocyte responses tooxidative and mechanical stress. Myocardial collagen deposition can affect cardiac compliance and contractility. The aimof the present study was to determine whether the silencing of FAK is protective against endotoxemia-induced alterationsof cardiac structure and function. In male Wistar rats, endotoxemia was induced by intraperitoneal injection oflipopolysaccharide (10 mg/kg). Cardiac morphometry and function were studied in vivo by left ventricular catheterizationand histology. Intravenous injection of small interfering RNA targeting FAK was used to silence myocardial expression ofthe kinase. The hearts of lipopolysaccharide-injected rats showed collagen deposition, increased matrix metalloproteinase2 activity, and myocyte hypertrophy, as well as reduced 24-h +dP/dt and jdP/dt, together with hypotension, increased leftventricular end-diastolic pressure, and elevated levels of FAK (phosphorylated and unphosphorylated). Focal adhesionkinase silencing reduced the expression and activation of the kinase in cardiac tissue, as well as protecting against theincreased collagen deposition, greater matrix metalloproteinase 2 activity, and reduced cardiac contractility that occurduring endotoxemia. In conclusion, FAK is activated in endotoxemia, playing a role in cardiac remodeling and in theimpairment of cardiac function. This kinase represents a potential therapeutic target for the protection of cardiac function inpatients with sepsis.KEYWORDS—Focal adhesion protein-tyrosine kinases, cytokines, inflammation, sepsis, shock septic

Signal transduction through the surface molecule CD40 is critical for cellular activation in immunoinflammatory states such as sepsis. The mechanisms regulating this pathway are not completely understood. Because CD40 displays potentially regulatory cysteine residues and CD40 is probably exposed to NO in the inflammatory milieu, we hypothesized that S-nitrosylation, the interaction of NO with cysteines residues, acts as a post-translational modification on CD40, coregulating the signaling activity and, therefore, the level of cellular activation. As assessed by the biotin switch and the reduction/chemiluminescence S-nitrosylation detection techniques, CD40 was found to be S-nitrosylated endogenously and upon exposure to NO donors in both human and murine macrophages. S-nitrosylation of CD40 was associated with milder activation by its ligand (CD40L), leading to reduced in vitro cytokine (IL-1beta, IL-12, and TNF-alpha) production, which was reversed in the presence of inhibitors of NO synthesis. S-nitrosylated CD40 was found in resting RAW 246.7 macrophages and BALB/c mice peritoneal macrophages, turning into the denitrosylated state upon in vitro or systemic exposure, respectively, to LPS. Moreover, monocytes from patients with sepsis displayed denitrosylated CD40 in contrast to the CD40 S-nitrosylation measured in healthy individuals. Finally, in an attempt to explain how S-nitrosylation regulates CD40 activation, we demonstrate that NO affects the redistribution of CD40 on the cell surface, which is a requirement for optimal signal transduction. Our results support a novel post-translational regulatory mechanism in which the CD40 signal may be, at least in part, dependent on cellular activation-induced receptor denitrosylation.

Shock and resuscitation render patients more susceptible to acute lung injury due to an exacerbated immune response to subsequent inflammatory stimuli. To study the role of innate immunity in this situation, we investigated acute lung injury in an experimental model of ischemia-reperfusion (I-R) followed by an early challenge with live bacteria. Conscious rats (N = 8 in each group) were submitted to controlled hemorrhage and resuscitated with isotonic saline (SS, 0.9% NaCl) or hypertonic saline (HS, 7.5% NaCl) solution, followed by intratracheal or intraperitoneal inoculation of Escherichia coli. After infection, toll-like receptor (TLR) 2 and 4 mRNA expression was monitored by RT-PCR in infected tissues. Plasma levels of tumor necrosis factor alpha and interleukins 6 and 10 were determined by ELISA. All animals showed similar hemodynamic variables, with mean arterial pressure decreasing to nearly 40 mmHg after bleeding. HS or SS used as resuscitation fluid yielded equal hemodynamic results. Intratracheal E. coli inoculation per se induced a marked neutrophil infiltration in septa and inside the alveoli, while intraperitoneal inoculation-associated neutrophils and edema were restricted to the interseptal space. Previous I-R enhanced lung neutrophil infiltration upon bacterial challenge when SS was used as reperfusion fluid, whereas neutrophil influx was unchanged in HS-treated animals. No difference in TLR expression or cytokine secretion was detected between groups receiving HS or SS. We conclude that HS is effective in reducing the early inflammatory response to infection after I-R, and that this phenomenon is achieved by modulation of factors other than expression of innate immunity components.

Objectives: Acute pancreatitis (AP) protease release induces lung parenchymal destruction via matrix metalloproteinases (MMPs), a neutrophil (polymorphonuclear leukocyte)-dependent process. Recent studies in hemorrhagic shock revealed that hypertonic saline (HTS) has an anti-inflammatory effect and can inhibit a variety of neutrophil functions. The aim of this study was to determine whether HTS and its actions in the pathway of neutrophil migration, MMPs, and heat shock proteins (HSPs) are effective in protecting the lung from injury associated with AP. Methods: We determined neutrophil infiltration and expressions of MMPs and HSPs in the lung tissue after AP induced by retrograde infusion of 2.5% of sodium taurocholate. Results: Animals submitted to AP that received HTS compared with those who received normal saline presented with increased HSP70 and HSP90 expressions and reduced myeloperoxidase levels and MMP-9 expression and activity. Conclusions: Our data raised the hypothesis that a sequence of HTS lung protection events increases HSP70 and HSP90, inhibiting infiltration of neutrophils and their protease actions in the lung.

The signalling pathway CD40/CD40L (CD40 ligand) plays an important role in atherosclerotic plaque formation and rupture. AngII (angiotensin II), which induces oxidative stress and inflammation, is also implicated in the progression of atherosclerosis. In the present study, we tested the hypothesis that AngII increases CD40/CD40L activity in vascular cells and that ROS (reactive oxygen species) are part of the signalling cascade that controls CD40/CD40L expression. Human CASMCs (coronary artery smooth muscle cells) in culture exposed to IL (interleukin)-1β or TNF-α (tumour necrosis factor-α) had increased superoxide generation and enhanced CD40 expression, detected by EPR (electron paramagnetic resonance) and immunoblotting respectively. Both phenomena were abolished by previous incubation with membrane-permeant antioxidants or cell transfection with p22phoxantisense. AngII (50–200 nmol/l) induced an early and sustained increase in CD40 mRNA and protein expression in CASMCs, which was blocked by treatment with antioxidants. Increased CD40 expression led to enhanced activity of the pathway, as AngII-treated cells stimulated with recombinant CD40L released higher amounts of IL-8 and had increased COX-2 (cyclo-oxygenase-2) expression. We conclude that AngII stimulation of vascular cells leads to a ROS-dependent increase in CD40/CD40L signalling pathway activity. This phenomenon may be an important mechanism modulating the arterial injury observed in atherosclerosis-related vasculopathy.

Mice expressing human cholesteryl ester transfer protein (huCETP) are more resistant to Escherichia coli bacterial wall LPS because death rates 5 days after intraperitoneal inoculation of LPS were higher in wild-type than in huCETP+/+ mice, whereas all huCETP+/+ mice remained alive. After LPS inoculation, plasma concentrations of TNF-alpha and IL-6 increased less in huCETP+/+ than in wild-type mice. LPS in vitro elicited lower TNF-alpha production by CETP expressing than by wild-type macrophages. In addition, TNF-alpha production by RAW 264.7 murine macrophages increased on incubation with LPS but decreased in a dose-dependent manner when human CETP was added to the medium. Human CETP in vitro enhanced the LPS binding to plasma high-density lipoprotein/low-density lipoprotein. The liver uptake of intravenous infused 14C-LPS from Salmonella typhimurium was greater in huCETP+/+ than in wild-type mice. Present data indicate for the first time that CETP is an endogenous component involved in the first line of defense against an exacerbated production of proinflammatory mediators.

Parenteral glutamine supplementation in acute inflammatory conditions is controversial. We evaluated the inflammatory and survival responses after parenteral glutamine infusion in sodium taurocholate-induced acute pancreatitis (AP) model. Lewis rats received 1 g/kg parenteral glutamine (n=42), saline (n=44), or no treatment (n=45) for 48 h before AP induction. Blood, lung, and liver samples were collected 2, 12, and 24 h after AP to measure serum cytokines levels and tissue heat shock protein (HSP) expression. From each group, 20 animals were not sacrificed after AP for a 7-day mortality study. Serum cytokine levels did not differ among groups at any time point, but the intragroup analysis over time showed higher interferon-γonly in the nontreatment and saline groups at 2 h (versus 12 and 24 h; bothp≤0.05). The glutamine group exhibited greater lung and liver HSP90 expression than did the nontreatment group at 2 and 12 h, respectively; greater liver HSP90 and HSP70 expression than did the saline group at 12 h; and smaller lung HSP70 and liver HSP90 expression than did the nontreatment group at 24 h (allp≤0.019). The 7-day mortality rate did not differ among groups. In experimental AP, pretreatment with parenteral glutamine was safe and improved early inflammatory mediator profiles without affecting mortality.

Aims Changes in the gene expression are one of the molecular events involved in the Systemic of Inflammatory Response Syndrome during sepsis. The preconditioning with low doses of lipopolysaccharide (LPS) reduces the expression of pro-inflammatory genes leading to less tissue damage and better outcome. This hyporesponsive state called tolerance is associated to alterations in chromatin structure and nitric oxide (NO) production. In the current study, we demonstrated that tolerance induced by LPS was found to be NO-dependent and related to epigenetic changes. Main methods THP-1 cells were cultivated in RPMI medium (Control), submitted to tolerance (500 ng/mL of LPS 24 h before challenge with 1000 ng/mL of LPS during 24 h Tolerant group) and challenge (1000 ng/mL of LPS during 24 h Directly challenged group). The analyses performed were: cytokines production, histone acetyl transferases/histone deacetylases (HAT/HDAC) activity, nitrosylation of HDAC-2 and -3, expression of acetylated histones H3 and H4. HDAC and Nitric Oxide Synthases (NOS) activities were inhibited with 30 mM trichostatin (TSA) and 100 μM LNAME, respectively. Key findings Administration of low doses of LPS repressed the production of IL-6 and IL-10, however this effect was abolished with the inhibition of NOS activity and by TSA in the case of IL-10. Tolerance modulates the activity of HAT and, consequently, the acetylation of histones H3 and H4. Inhibition of NO decreases acetylation of Histones. The HDACs 2 and 3 were nitrosylated after the tolerance induction. Significance The tolerance to LPS regulates the cytokine production by modulating chromatin structure and this event is NO dependent.

Hypertonic saline solution (HS solution, NaCl 7.5%) has shown to restore hemodynamic parameters in hemorrhagic shock and to decrease the inflammation triggered by ischemia-reperfusion injury (I-R). Therefore, our objective was to investigate the effects of HS solution on the mechanisms involved in I-R, in an experimental model of controlled hemorrhagic shock. Wistar rats (280-350 g) were submitted to controlled bleeding, keeping the mean arterial pressure around 40 mmHg, for 1 h. After that, rats were randomized and treated with HS solution (4 mL/kg) or normal saline (34 mL/kg). There were no differences in hemodynamic parameters between both groups for at least 2 h after shock. No difference either was observed in reactive oxygen species generation (measured indirectly by malondialdehyde concentration) or cytokines (interleukins 6 and 10) production (measured by enzyme-linked immunosorbent assay). Quantitative analysis of lung tissue showed a smaller neutrophil infiltration in animals that received HS solution. Moreover, the animals in the HS group showed an increased expression of heat shock protein 70. Therefore, we concluded that treatment of hemorrhagic shock with HS solution can decrease pulmonary inflammation and increase cellular protection by up-regulating heat shock protein 70 expression.

A lesão pulmonar é determinante da morbi-mortalidade na pancreatite aguda (PA). Neutrófilos (PMN) e mediadores inflamatórios são responsáveis pelo desenvolvimento da lesão. A solução hipertônica modula a reposta inflamatória tendo como resultante um efeito imunomodulatório capaz de prevenir a lesão tecidual. Neste trabalho, investigamos os efeitos da solução hipertônica sobre os níveis de HSPs, MMPs e citocinas no tecido pulmonar, bem como, o mecanismo envolvido em sua regulação. Ratos machos Wistar foram submetidos a pancreatite pela injeção retrógrada de 1 ml/Kg de taurocolato de sódio 2,5%. Os animais foram randomizados em 4 grupos: 1) controle: não foi submetido a qualquer procedimento; 2) pancreatite sem tratamento (ST); 3) pancreatite e tratamento com solução fisiológica (SF); 4) pancreatite e tratamento com solução hipertônica (SH). Os animais dos grupos 3 e 4 tiveram a veia jugular cateterizada e receberam infusão de solução hipertônica ou fisiológica 1 hora após a indução de pancreatite. Os animais com PA foram sacrificados após 4, 12 e 24 horas. Os pulmões foram processados e submetidos a histologia com HE e dosagem de mieloperoxidase (MPO) para quantificação do infiltrado de neutrófilos. A produção e atividade das MMPs 2 e 9 foi analisada por zimografia. Western Blotting foi utilizado na detecção das HSPs 60, 70 e 90. As alterações na expressão gênica foram analisadas por RTPCR. Os níveis de peroxidação lipidica dosados por TBARs. A concentração de citocinas foi medida por ELISA. A reposição volêmica com SHT diminui o infiltrado inflamatório (PMN) 12 horas após a indução da PA. Concomitante a redução dos PMNs vimos a queda na atividade e expressão da MMP-9 e aumento da expressão protéica de HSP70 no tecido pulmonar. Tardiamente, 24 horas, o grupo tratado com SHT mostrou aumento na produção de IL-10, uma citocina anti-inflamatória. A SHT modula a resposta inflamatória, promovendo proteção ao tecido pulmonar contra os efeitos deletérios decorrentes da PA. Seus efeitos benéficos envolvem alterações celulares e moleculares que levam à redução da lesão tecidual. Acute Pancreatitis (AP) is an inflammatory process of the pancreas with variable involvement of other organs and systems. The lungs are the most common distant organs affected by severe acute pancreatitis. The immunomodulatory effects of hypertonic solution (HS) provide potential strategies to attenuate inappropriate inflammatory reactions. This study tested the hypothesis that administration of HS modulates the development of lung injury in pancreatitis model. HS resuscitation results in a significant attenuation of lung injury following AP by modulate MMP 2 and 9 activity and protected tissue by increased HSPs 70 and 90 expression.

Acute lung injury is a condition characterized by exacerbate inflammatory reaction in distal airways and lung dysfunction. Here we investigate the treatment of acute lung injury (ALI) by low level laser therapy (LLLT), an effective therapy used for the treatment of patients with inflammatory disorders or traumatic injuries, due to its ability to reduce inflammation and promote tissue regeneration. However, studies in internal viscera remains unclear. C57BL/6 mice were treated with intratracheal lipopolysaccharide (LPS) (5 mg/kg) or phosphate buffer saline (PBS). Six hours after instillation, two groups were irradiated with laser at 660 nm and radiant exposure of 10 J/cm2 . Intratracheal LPS inoculation induced a marked increase in the number of inflammatory cells in perivascular and alveolar spaces. There was also an increase in the expression and secretion of cytokines (TNF-α, IL-1β, IL-6,) and chemokine (MCP-1). The LLLT application induced a significant decrease in both inflammatory cells influx and inflammatory mediators secretion. These effects did not affect lung mechanical properties, since no change was observed in tissue resistance or elastance. In conclusion LLLT is able to reduce inflammatory reaction in lungs exposed to LPS without affecting the pulmonary function and recovery.

Objetivo: Investigar o papel de duas diferentes solucoes salinas nos mecanismos de lesao apos isquemia intestinal: estresse oxidativo e respostas inflamatorias. Metodos: Ratos Wistar foram submetidos a oclusao transitoria da arteria mesenterica superior e estudados durante as 6 horas seguintes a reperfusao. Apos randomizacao, os animais foram divididos em quatro grupos: Falso; Solucao Hipertonica, os quais receberam infusao de solucao salina hipertonica a 7,5% (4mL/kg de peso corporeo); Solucao Fisiologica, os quais receberam infusao de solucao salina a 0,9% (33mL/kg); e Sem Tratamento. A infusao foi realizada imediatamente antes da reperfusao. Foram realizadas dosagens sequenciais de interleucina 6 e interleucina 10 no plasma. Foram coletadas amostras de tecidos (pulmao, figado e intestino) para medir malondialdeido, mieloperoxidase e interleucina. Resultados: Em comparacao ao Grupo Sem Tratamento, os animais que receberam volume (Grupos Solucao Hipertonica e Solucao Fisiologica) mostraram niveis tissulares mais baixos de malondialdeido, mieloperoxidase, interleucina 6 e interleucina 10. As concentracoes plasmaticas de interleucina 6 e interleucina 10 foram mais altas nos animais tratados com solucao hipertonica do que nos tratados com solucao fisiologica e nos sem tratamento. Conclusao: Neste modelo de isquemia intestinal transitoria, a manutencao adequada de volume intravascular diminuiu o estresse oxidativo e a sintese de marcadores de inflamacao. Tanto a solucao hipertonica quanto a fisiologica atenuaram os efeitos deleterios observados apos isquemia intestinal.

Protein disulfide isomerase (PDI) is a dithiol-disulfide oxidoreductase that has essential roles in redox protein folding. PDI has been associated with protective roles against protein aggregation, a hallmark of neurodegenerative diseases. Intriguingly, PDI has been detected in the protein inclusions found in the central nervous system of patients of neurodegenerative diseases. Oxidized proteins are also consistently detected in such patients, but the agents that promote these oxidations remain undefined. A potential trigger of protein oxidation is the bicarbonate-dependent peroxidase activity of the human enzyme superoxide dismutase 1 (hSOD1). Therefore, we examined the effects of this activity on PDI structure and activity. The results showed that PDI was oxidized to radicals that lead to PDI inactivation and aggregation. The aggregates are huge and apparently produced by covalent cross-links. Spin trapping experiments coupled with MS analysis indicated that at least 3 residues of PDI are oxidized to tyrosyl radicals (Y(63), Y(116) and Y(327)). Parallel experiments showed that PDI is also oxidized to radicals, inactivated and aggregated by the action of photolytically generated carbonate radical and by UV light. PDI is prone to inactivation and aggregation by one-electron oxidants and UV light probably because of its high content of aromatic amino acids.

It is known that low level laser therapy is able to improve skin flap viability by increasing angiogenesis. However, the mechanism for new blood vessel formation is not completely understood. Here, we investigated the effects of 660 nm and 780 nm lasers at fluences of 30 and 40 J/cm(2) on three important mediators activated during angiogenesis. Sixty male Wistar rats were used and randomly divided into five groups with twelve animals each. Groups were distributed as follows: skin flap surgery non-irradiated group as a control; skin flap surgery irradiated with 660 nm laser at a fluence of 30 or 40 J/cm(2) and skin flap surgery irradiated with 780 nm laser at a fluence of 30 or 40 J/cm(2). The random skin flap was performed measuring 10×4 cm, with a plastic sheet interposed between the flap and the donor site. Laser irradiation was performed on 24 points covering the flap and surrounding skin immediately after the surgery and for 7 consecutive days thereafter. Tissues were collected, and the number of vessels, angiogenesis markers (vascular endothelial growth factor, VEGF and hypoxia inducible factor, HIF-1α) and a tissue remodeling marker (matrix metalloproteinase, MMP-2) were analyzed. LLLT increased an angiogenesis, HIF-1α and VEGF expression and decrease MMP-2 activity. These phenomena were dependent on the fluences, and wavelengths used. In this study we showed that LLLT may improve the healing of skin flaps by enhancing the amount of new vessels formed in the tissue. Both 660 nm and 780 nm lasers were able to modulate VEGF secretion, MMP-2 activity and HIF-1α expression in a dose dependent manner.

The experimental model of aortocaval fistula is a useful model of cardiac hypertrophy in response to volume overload. In the present study it has been used to investigate the pathologic subendocardial remodeling associated with the development of heart failure during the early phases (day 1, 3, and 7) following volume overload. Compared with sham treated rats, aortocaval fistula rats showed lower systemic blood pressure and higher left ventricular end-diastolic pressure This resulted in lower coronary driving pressure and left ventricular systolic and diastolic dysfunction. Signs of myocyte necrosis, leukocyte cell infiltration, fibroplasia and collagen deposition appeared sequentially in the subendocardium where remodeling was more prominent than in the non-subendocardium. Accordingly, increased levels of TNF-alpha, IL-1 beta, and IL-6, and enhanced MMP-2 activity were all found in the subendocardium of rats with coronary driving pressure ≤ 60 mmHg. The coronary driving pressure was inversely correlated with MMP-2 activity in subendocardium in all time-points studied, and blood flow in this region showed positive correlation with systolic and diastolic function at day 7. Thus the predominant subendocardial remodeling that occurs in response to low myocardial perfusion pressure during the acute phases of aortocaval fistula contributes to early left ventricular dysfunction.

Uric acid is associated with endothelial dysfunction and progression of cardiovascular disease. When oxidize by plasma peroxidases, uric acid is converted into urate free radical and urate hydroperoxide. Urate hydroperoxide oxidizes small antioxidants like glutathione and methionine and might target thiol groups from proteins in endothelial cell surface. The protein disulfide isomerase (PDI) is a redox sensitive protein that can be found (1 - 2 % of its total expression) at the external surface of the cell (PecPDI). PecPDI is involved in vascular remodeling, platelet adhesion and thrombus formation in a redox-dependent way. Our aim was to investigate whether PDI would be a target to urate hydroperoxide and if it would alter the endothelial cell function. When incubated with recombinant PDI, urate hydroperoxide was rapidly reduced to hydroxyisourate and the thiol groups from PDI were oxidized. The rate constant for this oxidation was 6 × 10 3 M -1 s -1 . After marking surface reduced proteins with the biotinylating reagent Na-(3-maleimidylpropionyl) biocytin, we observe that lower concentrations of urate hydroperoxide are already capable of increasing the extracellular pool of oxidized PDI in HUVECs. In addition, HUVECs exposed to increasing concentrations of urate hydroperoxide exhibited morphological changes - contracted and rounded - and became more sensitive to detachment from culture plates. Nevertheless, treatment with the oxidant did not result in severe cell death, as shown by the results of nuclear staining with specific dyes and detection of dehydrogenase lactate enzyme in supernatant. In conclusion, these results revealed that urate hydroperoxide is capable of causing disturbances in endothelial cells without leads them to death. The oxidation of PecPDI may be one of the mechanisms by which uric acid alters the vascular physiology and supports cardiovascular disease. Supported by: FAPESP CEPID-REDOXOMA 2013/07937-8 and 2011/18106-4, CNPq, CAPES, USP.

OBJETIVO: A falência hepática é uma consequência da inflamação sistêmica após pancreatite aguda. Avaliou-se o efeito da reposição volêmica com soluções salinas fisiológicas ou hipertônica na produção hepática de citocinas e na expressão de proteínas ativadas por choque térmico e proteínas ligadas à apoptose durante a pancreatite aguda. MÉTODOS: Ratos Wistar foram divididos em quatro grupos: C - animais controles não submetidos à lesão e nem ao tratamento; NT - animais submetidos à indução de pancreatite aguda e não tratados; SN - animais submetidos à indução de pancreatite aguda e tratados com solução salina normal (NaCl 0,9%); SH - animais submetidos à pancreatite aguda e tratados com solução salina hipertônica (NaCl 7,5%). A pancreatite aguda foi induzida por infusão retrógrada transduodenal de taurocolato de sódio 2,5% no ducto pancreático. Após 4, 12 e 24 horas da indução da pancreatite aguda, analisaram-se, no fígado, TNF-α, IL-1β, IL-6 e IL-10, caspase-2, caspase-7, APAF-1, AIF, HSP60 e HSP90. RESULTADOS: A caspase-2 diminuiu nos grupos SN e SH (p

Muscle regeneration is a complex phenomenon, involving replacement of damaged fibers by new muscle fibers. During this process, there is a tendency to form scar tissue or fibrosis by deposition of collagen that could be detrimental to muscle function. New therapies that could regulate fibrosis and favor muscle regeneration would be important for physical therapy. Low-level laser therapy (LLLT) has been studied for clinical treatment of skeletal muscle injuries and disorders, even though the molecular and cellular mechanisms have not yet been clarified. The aim of this study was to evaluate the effects of LLLT on molecular markers involved in muscle fibrosis and regeneration after cryolesion of the tibialis anterior (TA) muscle in rats. Sixty Wistar rats were randomly divided into three groups: control, injured TA muscle without LLLT, injured TA muscle treated with LLLT. The injured region was irradiated daily for four consecutive days, starting immediately after the lesion using an AlGaAs laser (808 nm, 30 mW, 180 J/cm(2); 3.8 W/cm(2), 1.4 J). The animals were sacrificed on the fourth day after injury. LLLT significantly reduced the lesion percentage area in the injured muscle (p

Prosthetic mesh implants are commonly used to correct abdominal wall defects. However, success of the procedure is conditioned by an adequate inflammatory response to the device. We hypothesized that nitric oxide produced by nitric oxide synthase 2 (NOS2) and MMP-2 and -9 participate in response induced by mesh implants in the abdominal wall and, consequently, affect the outcome of the surgical procedure. In the first step, temporal inflammatory markers profile was evaluated. Polypropylene meshes were implanted in the peritoneal side of the abdominal wall of C57Black mice. After 2, 4, 7, 15, and 30 days, tissues around the mesh implant were collected and inflammatory markers were analyzed. In the second step, NOS2 activity was inhibited with nitro-L-arginine methyl ester (L-NAME). Samples were collected after 15 days (when inflammation was reduced), and the inflammatory and tissue remodeling markers were investigated. Polypropylene mesh implant induced a pro-inflammatory environment mediated by intense MMP-2 and -9 activities, NO release, and interleukin-1β production peaking in 7 days and gradually decreasing after 15 days. NOS2 inhibition increased MMP-2 activity and resulted in a higher visceral adhesion incidence at the mesh implantation site when compared with non-treated animals that underwent the same procedure. We conclude that NOS2-derived NO is crucial for adequate response to polypropylene mesh implant integration in the peritoneum. NO deficiency results in an imbalance between extracellular matrix deposition/degradation contributing to visceral adhesions incidence. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2013.

Prosthetic meshes are commonly used to correct abdominal wall defects. However, the inflammatory reaction induced by these devices in the peritoneum is not completely understood. We hypothesized that nitric oxide (NO), produced by nitric oxide synthase 2 (NOS2) may modulate the response induced by mesh implants in the abdominal wall and, consequently, affect the outcome of the surgical procedure. Polypropylene meshes were implanted in the peritoneal side of the abdominal wall in wild-type and NOS2-deficient (NOS2(-/-)) mice. After 15 days tissues around the mesh implant were collected, and inflammatory markers (the cytokine interleukin 1β (IL-1β) and NO) and tissue remodeling (collagen and metalloproteinases (MMP) 2 and 9) were analyzed. The lack of NOS2-derived NO induced a higher incidence of visceral adhesions at the mesh implantation site compared with wild-type mice that underwent the same procedure (P

1. We recently demonstrated that hypertonic saline reduces inflammation and mortality in acute pancreatitis. The present study investigated the effects of hypertonic saline in metalloproteinase (MMP) regulation and pancreatitis-associated hepatic injury. 2. Wistar rats were divided into four groups: (i) control, not subjected to insult or treatment; (ii) no treatment (NT), induction of pancreatitis (retrograde infusion of 2.5% sodium taurocholate (1.0 mL/kg)), but no further treatment; (iii) normal saline (NS), induction of pancreatitis and treatment with normal saline (0.9% NaCl, 34 mL/kg, i.v. bolus, 1 h after the induction of pancreatitis); and (iv) hypertonic saline (HS), induction of pancreatitis and treatment with hypertonic saline (7.5% NaCl, 4 mL/kg administered over a period of 5 min, 1 h after the induction of pancreatitis). In all four groups, 4, 12 and 24 h after the induction of pancreatitis, liver tissue samples were assayed to determine levels of MMP-2, MMP-9, 47 kDa heat shock protein (HSP47) and collagen (Type I and III). 3. Compared with the control group, MMP-9 expression and activity was increased twofold in the NS and NT groups 4 and 12 h after the induction of pancreatitis, but remained at basal levels in the HS group. In contrast, MMP-2 expression was increased twofold 12 h after the induction of pancreatitis only in the NS group, whereas the expression of HSP47 was increased 4 h after the induction of pancreatitis in the NS and NT groups. Greater extracellular matrix remodelling occurred in the NS and NT groups compared with the HS group, probably as a result of the hepatic wound-healing response to repeated injury. However, the collagen content in hepatic tissue remained at basal levels in the HS group. 4. In conclusion, the results of the present study indicate that hypertonic saline is hepatoprotective and reduces hepatic remodelling, maintaining the integrity of the hepatic extracellular matrix during pancreatitis. Hypertonic saline-mediated regulation of MMP expression may have clinical relevance in pancreatitis-associated liver injury.

SUMMARY 1 The role of haemodynamic changes in left ventricular remodelling has been poorly investigated, especially in the context of volume overload cardiac hypertrophy. Low diastolic blood pressure and high left ventricular filling pressure are expected to affect coronary driving pressure negatively and thereby put in jeopardy subendocardial perfusion in particular. The consequences to global left ventricular remodelling remain undetermined. The aim of the present study was to investigate the role of coronary driving pressure in the development of subendocardial remodelling and the conceivable effects on cardiac function, using a rat model of aortocaval fistula. 2 Wistar rats, weighing 330–350 g, were submitted to aortocaval fistula (ACF group) or sham (control group) operations. Two haemodynamic measurements were determined following surgery, the initial measurement at week 1 and the final measurement at week 8. Cytokine expression, myeloperoxidase (MPO) activity, metalloproteinase expression and activity and fibrosis were assessed in two distinct left ventricular myocardial layers: the subendocardium (SE) and the non-subendocardium (non-SE). 3 The ACF group showed lower initial and final coronary driving pressure and lower final +dP/dt and –dP/dt compared with the control group. Multivariate analyses disclosed initial coronary driving pressure as the only haemodynamic parameter independently associated with SE fibrosis (R2 = 0.76; P