Hypertonic saline solution increases the expression of heat shock protein 70 and improves lung inflammation early after reperfusion in a rodent model of controlled hemorrhage

Autophagy and Hsp70 activation alleviate oral epithelial cell death induced by food-derived hypertonicity

Stable intracellular and intercellular osmolarity is vital for all physiological processes. Although it is the first organ that receives food, the osmolarity around the mouth epithelium has never been systematically investigated. We found that oral epithelial cells are a population of ignored cells routinely exposed to hypertonic environments mainly composed of saline, glucose, etc. in vivo after chewing food. By using cultured oral epithelial cells as an in vitro model, we found that the hypotonic environments caused by both high NaCl and high glucose induced cell death in a dose- and time-dependent manner. Transcriptomics revealed similar expression profiles after high NaCl and high glucose stimulation. Most of the common differentially expressed genes were enriched in "mitophagy" and "autophagy" according to KEGG pathway enrichment analysis. Hypertonic stimulation for 1 to 6 h resulted in autophagosome formation. The activation of autophagy protected cells from high osmolarity-induced cell death. The activation of Hsp70 by the pharmacological activator handelin significantly improved the cell survival rate after hypertonic stimulation. The protective role of Hsp70 activation was partially dependent on autophagy activation, indicating a crosstalk between Hsp70 and autophagy in hypertonic stress response. The extract of the handelin-containing herb Chrysanthemum indicum significantly protected oral epithelial cells from hypertonic-induced death, providing an inexpensive way to protect against hypertonic-induced oral epithelial damage. In conclusion, the present study emphasized the importance of changes in osmolarity in oral health for the first time. The identification of novel compounds or herbal plant extracts that can activate autophagy or HSPs may contribute to oral health and the food industry.

Heat-shock response increases lung injury caused by Pseudomonas aeruginosa via an interleukin-10-dependent mechanism in mice

BACKGROUND

The heat-shock response (HSR) protects from insults, such as ischemia-reperfusion injury, by inhibiting signaling pathways activated by sterile inflammation. However, the mechanisms by which the HSR activation would modulate lung damage and host response to a bacterial lung infection remain unknown.

METHODS

HSR was activated with whole-body hyperthermia or by intraperitoneal geldanamycin in mice that had their lungs instilled with Pseudomonas aeruginosa 24 h later (at least six mice per experimental group). Four hours after instillation, lung endothelial and epithelial permeability, bacterial counts, protein levels in bronchoalveolar lavage fluid, and lung myeloperoxidase activity were measured. Mortality rate 24 h after P. aeruginosa instillation was recorded. The HSR effect on the release of interleukin-10 and killing of P. aeruginosa bacteria by a mouse alveolar macrophage cell line and on neutrophil phagocytosis was also examined.

RESULTS

HSR activation worsened lung endothelial (42%) and epithelial permeability (50%) to protein, decreased lung bacterial clearance (71%), and increased mortality (50%) associated with P. aeruginosa pneumonia, an effect that was not observed in heat-shock protein-72-null mice. HSR-mediated decrease in neutrophil phagocytosis (69%) and bacterial killing (38%) by macrophages was interleukin-10 dependent, a mechanism confirmed by increased lung bacterial clearance and decreased mortality (70%) caused by P. aeruginosa pneumonia in heat-shocked interleukin-10-null mice.

CONCLUSIONS

Prior HSR activation worsens lung injury associated with P. aeruginosa pneumonia in mice via heat-shock protein-72- and interleukin-10-dependent mechanisms. These results provide a novel mechanism for the immunosuppression observed after severe trauma that is known to activate HSR in humans.

Low-level laser therapy restores the oxidative stress balance in acute lung injury induced by gut ischemia and reperfusion

It remains unknown if the oxidative stress can be regulated by low-level laser therapy (LLLT) in lung inflammation induced by intestinal reperfusion (i-I/R). A study was developed in which rats were irradiated (660 nm, 30 mW, 5.4 J) on the skin over the bronchus and euthanized 2 h after the initial of intestinal reperfusion. Lung edema and bronchoalveolar lavage fluid neutrophils were measured by the Evans blue extravasation and myeloperoxidase (MPO) activity respectively. Lung histology was used for analyzing the injury score. Reactive oxygen species (ROS) was measured by fluorescence. Both expression intercellular adhesion molecule 1 (ICAM-1) and peroxisome proliferator-activated receptor-y (PPARy) were measured by RT-PCR. The lung immunohistochemical localization of ICAM-1 was visualized as a brown stain. Both lung HSP70 and glutathione protein were evaluated by ELISA. LLLT reduced neatly the edema, neutrophils influx, MPO activity and ICAM-1 mRNA expression. LLLT also reduced the ROS formation and oppositely increased GSH concentration in lung from i-I/R groups. Both HSP70 and PPARy expression also were elevated after laser irradiation. Results indicate that laser effect in attenuating the acute lung inflammation is driven to restore the balance between the pro- and antioxidants mediators rising of PPARy expression and consequently the HSP70 production.

Pulmonary impact of N-acetylcysteine in a controlled hemorrhagic shock model in rats

BACKGROUND

Experimental hemorrhagic shock (HS) is based on controlling bleeding and the treatment of fluid resuscitation to restore tissue oxygenation and perfusion. The HS could promote ischemia/reperfusion injury, which induces a general exacerbation of the inflammatory process, initially compromising the lungs. N-acetylcysteine (NAC), an antioxidant, may attenuate ischemia/reperfusion injury. This study evaluated the effect of NAC in association with fluid resuscitation on pulmonary injury in a controlled HS model in rats.

METHODS

Male Wistar rats were submitted to controlled HS (mean arterial pressure of 35 mm Hg for 60 min). Two groups were constituted according to resuscitation solution administered: RLG (Ringer's lactate solution) and RLG+NAC (Ringer's lactate in association with 150 mg/kg NAC. A control group was submitted to catheterization only. After 120 min of resuscitation, bronchoalveolar lavage was performed to assess intra-alveolar cell infiltration and pulmonary tissue was collected for assessment of malondialdehyde, interleukin 6, and interleukin 10 and histopathology.

RESULTS

Compared with the RLG group, the RLG+NAC group showed lower bronchoalveolar lavage inflammatory cell numbers, lower interstitial inflammatory infiltration in pulmonary parenchyma, and lower malondialdehyde concentration. However, tissue cytokine (interleukin 6 and interleukin 10) expression levels were similar.

CONCLUSION

N-acetylcysteine was associated with fluid resuscitation-attenuated oxidative stress and inflammatory cell infiltration in pulmonary parenchyma. N-acetylcysteine did not modify cytokine expression.

Pentraxin 3 accelerates lung injury in high tidal volume ventilation in mice

Mechanical ventilation is the major cause of iatrogenic lung damage in intensive care units. Although inflammation is known to be involved in ventilator-induced lung injury (VILI), several aspects of this process are still unknown. Pentraxin 3 (PTX3) is an acute phase protein with important regulatory functions in inflammation which has been found elevated in patients with acute respiratory distress syndrome. This study aimed at investigating the direct effect of PTX3 production in the pathogenesis of VILI. Genetically modified mice deficient and that over express murine Ptx3 gene were subjected to high tidal volume ventilation (V(T)=45 mL/kg, PEEP(zero)). Morphological changes and time required for 50% increase in respiratory system elastance were evaluated. Gene expression profile in the lungs was also investigated in earlier times in Ptx3-overexpressing mice. Ptx3 knockout and wild-type mice developed same lung injury degree in similar times (156±42 min and 148±41 min, respectively; p=0.8173). However, Ptx3 over-expression led to a faster development of VILI in Ptx3-overexpressing mice (77±29 min vs 118±41 min, p=0.0225) which also displayed a faster kinetics of Il1b expression and elevated Ptx3, Cxcl1 and Ccl2 transcripts levels in comparison with wild-type mice assessed by quantitative real-time polymerase chain reaction. Ptx3 deficiency did not impacted the time for VILI induced by high tidal volume ventilation but Ptx3-overexpression increased inflammatory response and reflected in a faster VILI development.

A murine model of hypertonic saline as a treatment for acute spinal cord injury: effects on autonomic outcome

Object

Spinal cord injury (SCI) continues to be a problem without a definitive cure. Research based on improved understanding of the immunological aspects of SCI has revealed targets for treating and ameliorating the extent of secondary injury. Hypertonic saline (HTS), a substance both easy to create and to transport, has been investigated as an immunologically active material that can be used in a clinically relevant interval after injury. In this pilot study, HTS was investigated in a murine model for its abilities to ameliorate secondary injury after a severe spinal cord contusion.

Methods

Female C57Bl/6 mice with severe T8–10 contusion injuries were used as the model subjects. A group of 41 mice were studied in a blinded fashion. Mice received treatments with HTS (HTS, 7.5%) or normal saline solution (NSS, 0.9%) at 2 discreet time points (3 and 24 hours after injury.) A separate group of 9 untreated animals were also used as controls. Animals were assessed for autonomic outcome (bladder function). In a group of 33 mice, histological assessment (cellular infiltration) was also measured.

Results

Bladder function was found to be improved significantly in those treated with HTS compared with those who received NSS and also at later treatment times (24 hours) than at earlier treatment times (3 hours). Decreased cellular infiltration in each group correlated with bladder recovery.

Conclusions

The increased effectiveness of later administration time of the more osmotically active and immunomodulatory substance (HTS) suggests that interaction with events occurring around 24 hours after injury is critical. These events may be related to the invasion of leukocytes peaking at 8–24 hours postinjury and/or the peak benefit time of subject rehydration.

Hypertonic saline and reduced peroxynitrite formation in experimental pancreatitis

OBJECTIVES

In this study, we tested the hypothesis that hypertonic saline exerts anti-inflammatory effects by modulating hepatic oxidative stress in pancreatitis.

INTRODUCTION

The incidence of hepatic injury is related to severe pancreatitis, and hypertonic saline reduces pancreatic injury and mortality in pancreatitis.

METHODS

Wistar rats were divided into four groups: control (not subjected to treatment), untreated pancreatitis (NT, pancreatitis induced by a retrograde transduodenal infusion of 2.5% sodium taurocholate into the pancreatic duct with no further treatment administered), pancreatitis with normal saline (NS, pancreatitis induced as described above and followed by resuscitation with 0.9% NaCl), and pancreatitis with hypertonic saline (HS, pancreatitis induced as described above and followed by resuscitation with 7.5% NaCl). At 4, 12, and 24 h after pancreatitis induction, liver levels of inducible nitric oxide synthase (iNOS), heat-shock protein 70, nitrotyrosine (formation of peroxynitrite), nitrite/nitrate production, lipid peroxidation, and alanine aminotransferase (ALT) release were determined.

RESULTS

Twelve hours after pancreatitis induction, animals in the HS group presented significantly lower iNOS expression (P<0.01 vs. NS), nitrite/nitrate levels (P<0.01 vs. NS), lipid peroxidation (P<0.05 vs. NT), and ALT release (P<0.01 vs. NS). Twenty-four hours after pancreatitis induction, nitrotyrosine expression was significantly lower in the HS group than in the NS group (P<0.05).

DISCUSSION

The protective effect of hypertonic saline was related to the establishment of a superoxide-NO balance that was unfavorable to nitrotyrosine formation.

CONCLUSIONS

Hypertonic saline decreases hepatic oxidative stress and thereby minimizes liver damage in pancreatitis.

Pulmonary contusion: an update on recent advances in clinical management

Pulmonary contusion is a common finding after blunt chest trauma. The physiologic consequences of alveolar hemorrhage and pulmonary parenchymal destruction typically manifest themselves within hours of injury and usually resolve within approximately 7 days. Clinical symptoms, including respiratory distress with hypoxemia and hypercarbia, peak at about 72 h after injury. The timely diagnosis of pulmonary contusion requires a high degree of clinical suspicion when a patient presents with trauma caused by an appropriate mechanism of injury. The clinical diagnosis of acute parenchymal lung injury is usually confirmed by thoracic computed tomography, which is both highly sensitive in identifying pulmonary contusion and highly predictive of the need for subsequent mechanical ventilation. Management of pulmonary contusion is primarily supportive. Associated complications such as pneumonia, acute respiratory distress syndrome, and long-term pulmonary disability, however, are frequent sequelae of these injuries.

Fluid resuscitation: past, present, and the future

Hemorrhage remains a major cause of preventable death following both civilian and military trauma. The goals of resuscitation in the face of hemorrhagic shock are restoring end-organ perfusion and maintaining tissue oxygenation while attempting definitive control of bleeding. However, if not performed properly, resuscitation can actually exacerbate cellular injury caused by hemorrhagic shock, and the type of fluid used for resuscitation plays an important role in this injury pattern. This article reviews the historical development and scientific underpinnings of modern resuscitation techniques. We summarized data from a number of studies to illustrate the differential effects of commonly used resuscitation fluids, including isotonic crystalloids, natural and artificial colloids, hypertonic and hyperoncotic solutions, and artificial oxygen carriers, on cellular injury and how these relate to clinical practice. The data reveal that a uniformly safe, effective, and practical resuscitation fluid when blood products are unavailable and direct hemorrhage control is delayed has been elusive. Yet, it is logical to prevent this cellular injury through wiser resuscitation strategies than attempting immunomodulation after the damage has already occurred. Thus, we describe how some novel resuscitation strategies aimed at preventing or ameliorating cellular injury may become clinically available in the future.

Acute pancreatitis: hypertonic saline increases heat shock proteins 70 and 90 and reduces neutrophil infiltration in lung injury

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.

Hypertonic saline reduces metalloproteinase expression in liver during pancreatitis

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.

Hypertonic saline reduces inflammation and enhances the resolution of oleic acid induced acute lung injury

Background

Hypertonic saline (HTS) reduces the severity of lung injury in ischemia-reperfusion, endotoxin-induced and ventilation-induced lung injury. However, the potential for HTS to modulate the resolution of lung injury is not known. We investigated the potential for hypertonic saline to modulate the evolution and resolution of oleic acid induced lung injury.

Methods

Adult male Sprague Dawley rats were used in all experiments. Series 1 examined the potential for HTS to reduce the severity of evolving oleic acid (OA) induced acute lung injury. Following intravenous OA administration, animals were randomized to receive isotonic (Control, n = 12) or hypertonic saline (HTS, n = 12), and the extent of lung injury assessed after 6 hours. Series 2 examined the potential for HTS to enhance the resolution of oleic acid (OA) induced acute lung injury. Following intravenous OA administration, animals were randomized to receive isotonic (Control, n = 6) or hypertonic saline (HTS, n = 6), and the extent of lung injury assessed after 6 hours.

Results

In Series I, HTS significantly reduced bronchoalveolar lavage (BAL) neutrophil count compared to Control [61.5 ± 9.08 versus 102.6 ± 11.89 × 10³ cells.ml^-1]. However, there were no between group differences with regard to: A-a O2 gradient [11.9 ± 0.5 vs. 12.0 ± 0.5 KPa]; arterial PO2; static lung compliance, or histologic injury. In contrast, in Series 2, hypertonic saline significantly reduced histologic injury and reduced BAL neutrophil count [24.5 ± 5.9 versus 46.8 ± 4.4 × 10³ cells.ml^-1], and interleukin-6 levels [681.9 ± 190.4 versus 1365.7 ± 246.8 pg.ml^-1].

Conclusion

These findings demonstrate, for the first time, the potential for HTS to reduce pulmonary inflammation and enhance the resolution of oleic acid induced lung injury.