Hypertonic saline attenuation of the neutrophil cytotoxic response is reversed upon restoration of normotonicity and reestablished by repeated hypertonic challenge

Comparison of 20% mannitol and 3% hypertonic saline for intraoperative brain relaxation during supratentorial brain tumour craniotomy in patients with a midline shift

PURPOSE OF THE STUDY

A prospective, randomized, double-blind study was designed to assess differences in brain relaxation between 20% mannitol and 3% hypertonic saline (HS) during elective supratentorial brain tumour surgery in patients with midline shift.

MATERIAL AND METHODS

Sixty patients undergoing supratentorial craniotomy for tumour resection were enrolled to receive either 5mL/kg of 20% mannitol (n=30) or 3% HS (n=30) administered at skin incision. PCO2 in arterial blood was maintained within 35-40mmHg and arterial blood pressure was controlled within baseline values ±20%. The primary outcome was the proportion of satisfactory brain relaxation. The surgeon assessed brain relaxation on a four-point scale (1=excellent with no swelling, 2=minimal swelling, 3=serious swelling not requiring treatment, 4=severe swelling requiring treatment). Postsurgical intracranial changes determined by imaging techniques, postoperative complications, PACU and hospital stay, and mortality at 30 days were also recorded. Appropriate statistical tests were used for comparison; P<0.05 was considered as significant. This trial was registered in Eudract.ema.europa.eu (#2021-006290-40).

RESULTS

There was no difference in brain relaxation: 2.00 [1.00-2.00] and 2.00 [1.75-3.00] for patients in mannitol and HS groups, respectively (P=0.804). Tumour size (OR: 0.99, 95% CI: 0.99-1.01; P=0.371), peritumoral oedema classification (OR: 0.57, 95% CI: 0.11-2.84; P=0.493), mass effect (OR: 0.86, 95% CI: 0.16-4.87; P=0.864), anaesthesia (OR: 4.88, 95% CI: 0.82-28.96; P=0.081) and midline shift (OR: 5.00, 95% CI: 0.84-29.70; P=0.077) did not have a significant influence on brain swelling in patients treated with either mannitol or HS. No significant differences in perioperative outcomes, mortality and length of PACU and hospital stay were observed.

CONCLUSIONS

5mL/kg of 20% mannitol or 3% HS result in similar brain relaxation scores in patients undergoing craniotomy for supratentorial brain tumour with midline shift.

Use of Saline as a Placebo in Intra-articular Injections in Osteoarthritis: Potential Contributions to Nociceptive Pain Relief

Background:

Osteoarthritis of the knee (OAK) is a severe debilitating condition characterized by joint pain, stiffness, and resultant limited mobility. In recent years, intra-articular (IA) injections have been used to relieve symptoms and have succeeded to varying degrees either with sodium hyaluronate preparations or with a biologic.

Objective:

The objective of this review is to evaluate multiple studies that demonstrate some relief from the symptoms of OAK in the saline arm of various clinical trials.

Method:

A thorough literature search (PubMed) was performed assessing the pain efficacy of various compounds compared to saline injections in clinical trials. A total of 73 studies were identified in the literature search including a total of 5,816 patients. These clinical trials all involved the IA injection of a viscosupplement (hyaluronate, platelet rich plasma (PRP), etc.) or a biologic (the low molecular weight fraction (< 5kDa) of human serum albumin (LMWF-5A)). For all of these studies, the control arm was injection of sterile physiological saline that approximates the salt concentration and total solute concentration of blood and most tissues.

Results:

Based on our review of the current literature, the tested compounds performed with mixed results when compared to saline injections. Moreover, OAK is a variable disease, with severity measured on the Kellgren and Lawrence (KL) scale where various hyaluronate preparations have a therapeutic effect mostly on KL 2-3 patients while a biologic works best on KL 3-4 patients.

Conclusion:

Since the effect of saline injection is always greater than no treatment, the evaluations of these treatments can be confounded in clinical trials. Therefore, the question of whether there are known therapeutic effects of saline injections might explain these results.

The role of hypertonic saline dextran in trauma resuscitation

Modern trauma management has recognized the importance of using conservative fluid resuscitation regimes in order to prevent complications from fluid overload arising. Hypertonic/hyperoncotic fluids appear to provide an ideal means of facilitating this, requiring only small volumes to rapidly elevate blood pressure. Hypertonic saline dextran (HSD) was introduced in 1985 but its take up has been slow, a large part of this has been due to the lack of human trials and concerns about complications.

The current evidence has been reviewed and it is clear that HSD is an efficient means of correcting hypotension, doing so mainly by the mobilizing endogenous water. It is becoming apparent that early administration has the potential to modulate the inflammatory cascade in patients at risk of developing adult respiratory distress syndrome (ARDS) and multiorgan failure. This is reflected in the handful of human trials that show a trend towards increased survival (particularly for head injuries) and a possible reduction in ARDS. The side effect profile appears to be good, even in the presence of dehydration or penetrating trauma.

Published human trials have methodological problems and lack of power of study this has led to a reliance on animal studies. Clearly there is great potential, but before large-scale prehospital usage can be justified further well-conducted randomized human trials are needed.

Hypertonic Saline Primes Activation of the p53-p21 Signaling Axis in Human Small Airway Epithelial Cells That Prevents Inflammation Induced by Pro-inflammatory Cytokines

Uncontrolled inflammatory responses underlie the etiology of acute lung injury and acute distress respiratory syndrome, the most common late complications in trauma, the leading cause of death under the age of 59. Treatment with HTS decreases lung injury in clinical trials, rat models of trauma and hemorrhagic shock and inflammation in lung cell lines, although the mechanisms underlying these responses are still incompletely understood. Transcriptomics (RNaseq), proteomics, and U-¹³C-glucose tracing metabolomics experiments were performed to investigate the mechanisms of cellular responses to HTS treatment in primary small airway epithelial cells in the presence or absence of inflammatory injury mediated by a cocktail of cytokines (10 ng/mL of IFNγ, IL-1β, and TNFα). Modestly hyperosmolar HTS has an anti-inflammatory effect, triggers the p53-p21 signaling axis, and deregulates mitochondrial metabolism while inducing minimal apoptosis in response to a second hit by cytokines. Decreased transcription of pro-inflammatory cytokines suggested a role for the tumor suppressor protein p53 in mediating the beneficial effects of the HTS treatment. The anti-inflammatory mechanisms induced by HTS involves p53 gene regulation, promotes cell cycle arrest, and prevents ROS formation and mitochondria depolarization. Pharmaceutical targeting of the p53-p21 axis may mimic or reinforce the beneficial effects mediated by HTS when sustained hypertonicity cannot be maintained.

Hypertonic saline for brain relaxation and intracranial pressure in patients undergoing neurosurgical procedures: a meta-analysis of randomized controlled trials

Background

A wealth of evidence from randomized controlled trials (RCTs) has indicated that hypertonic saline (HS) is at least as effective as, if not better than, mannitol in the treatment of increased intracranial pressure(ICP). However, there is little known about the effects of HS in patients during neurosurgery. Thus, this meta-analysis was performed to compare the intraoperative effects of HS with mannitol in patients undergoing craniotomy.

Methods

According to the research strategy, we searched PUBMED, EMBASE and Cochrane Central Register of Controlled Trials. Other sources such as the internet-based clinical trial registries and conference proceedings were also searched. After literature searching, two investigators independently performed literature screening, quality assessment of the included trials and data extraction. The outcomes included intraoperative brain relaxation, intraoperative ICP, total volume of fluid required, diuresis, hemodynamic parameters, electrolyte level, mortality or dependence and adverse events.

Results

Seven RCTs with 468 participants were included. The quality of the included trials was acceptable. HS could significantly increase the odds of satisfactory intraoperative brain relaxation (OR: 2.25, 95% CI: 1.32–3.81; P = 0.003) and decrease the mean difference (MD) of maximal ICP (MD: −2.51mmHg, 95% CI: −3.39—1.93mmHg; P<0.00001) in comparison with mannitol with no significant heterogeneity among the study results. Compared with HS, mannitol had a more prominent diuretic effect. And patients treated with HS had significantly higher serum sodium than mannitol-treated patients.

Conclusions

Considering that robust outcome measures are absent because brain relaxation and ICP can be influenced by several factors except for the hyperosmotic agents, the results of present meta-analysis should be interpreted with cautions. Well-designed RCTs in the future are needed to further test the present results, identify the impact of HS on the clinically relevant outcomes and explore the potential mechanisms of HS.

Hyperosmolarity invokes distinct anti-inflammatory mechanisms in pulmonary epithelial cells: evidence from signaling and transcription layers

Hypertonic saline (HTS) has been used intravenously to reduce organ dysfunction following injury and as an inhaled therapy for cystic fibrosis lung disease. The role and mechanism of HTS inhibition was explored in the TNFα and IL-1β stimulation of pulmonary epithelial cells. Hyperosmolar (HOsm) media (400 mOsm) inhibited the production of select cytokines stimulated by TNFα and IL-1β at the level of mRNA translation, synthesis and release. In TNFα stimulated A549 cells, HOsm media inhibited I-κBα phosphorylation, NF-κB translocation into the nucleus and NF-κB nuclear binding. In IL-1β stimulated cells HOsm inhibited I-κBα phosphorylation without affecting NF-κB translocation or nuclear binding. Incubation in HOsm conditions inhibited both TNFα and IL-1β stimulated nuclear localization of interferon response factor 1 (IRF-1). Additional transcription factors such as AP-1, Erk-1/2, JNK and STAT-1 were unaffected by HOsm. HTS and sorbitol supplemented media produced comparable outcomes in all experiments, indicating that the effects of HTS were mediated by osmolarity, not by sodium. While not affecting MAPK modules discernibly in A549 cells, both HOsm conditions inhibit IRF-1 against TNFα or IL-1β, but inhibit p65 NF-kB translocation only against TNFα but not IL-1β. Thus, anti-inflammatory mechanisms of HTS/HOsm appear to disrupt cytokine signals at distinct intracellular steps.

Influence of preoperative 7.5% hypertonic saline on neutrophil activation after reamed intramedullary nailing of femur shaft fractures: a prospective randomized pilot study

OBJECTIVES

Femoral reaming and intramedullary nailing (IMN) primes polymorphonuclear leukocytes (PMNL) and thereby increases the posttraumatic systemic inflammatory response. Resuscitation with hypertonic saline (HTS) attenuates PMNL activation after trauma-hemorrhage. We hypothesized that preoperative administration of 7.5% HTS attenuates PMNL priming after IMN of unilateral femur shaft fractures compared with 0.9% normal saline.

DESIGN

Prospective, randomized, double-blind study.

SETTING

Level I trauma center.

PATIENTS

Twenty patients between 18 and 80 years of age with an Injury Severity Score less than 25 and a unilateral femur shaft fracture amenable to IMN fixation within 24 hours after injury.

INTERVENTION

Patients were allocated to equally sized HTS or normal saline treatment groups (n = 10) before surgery. Solutions were administered in a blinded bag as a single bolus of 4 mL/kg body weight immediately before surgery. Whole blood samples were collected directly before saline application (t0) and at 6, 12, and 24 hours after surgery.

MAIN OUTCOME MEASUREMENTS

PMNL surface expression of CD11b and CD62L, as determined by flow cytometry analysis.

RESULTS

Demographic characteristics of both treatment groups were comparable. Baseline expression of CD11b and CD62L cell markers was in a similar range in the two cohorts. The expression levels of CD11b were comparable between the two groups throughout the observation time, whereas CD62L levels were significantly higher in the HTS group at 6 and 24 hours after surgery.

CONCLUSION AND SIGNIFICANCE

Preoperative infusion of HTS appears to exert an anti-inflammatory effect by attenuating the extent of postoperative PMNL activation after reamed IMN for femoral shaft fractures.

Hypertonic saline inhibits arachidonic acid priming of the human neutrophil oxidase

BACKGROUND

Arachidonic acid (AA, and its leukotriene derivatives, e.g., LTB(4)) is an inflammatory mediator in post-shock mesenteric lymph that appears to act as an agonist on G-protein coupled receptors (GPCRs). These mediators prime neutrophils (PMNs) for an increased production of superoxide, implicated in the development of acute lung injury (ALI). Hypertonic saline (HTS) has also been shown to have immunomodulatory effects such as attenuation of PMN priming by precluding appropriate clathrin-mediated endocytosis of activated GPCRs, thereby potentially attenuating ALI. We hypothesize that HTS inhibits priming of the PMN oxidase by these lipid mediators.

METHODS

After PMNs were isolated from healthy donors, incubation was done in either isotonic buffer (control) or HTS (180 mmol/L) for 5 min at 37°C. The PMNs were then primed for 10 min with AA [5 μM] or 5 min with LTB(4) [1 μM] and the oxidase was activated with 200 ng/mL of phorbol 12-myristate 13-acetate (PMA), a non-GPCR activator, and superoxide anion generation was measured via reduction of cytochrome c.

RESULTS

Both AA [5 μM] and LTB(4) [1 μM] significantly primed the PMA activated respiratory burst (P < 0.05, ANOVA, Newman-Keuls, n = 4). HTS inhibited both AA and LTB(4) priming of the respiratory burst.

CONCLUSIONS

These data indicate that HTS reduces the cytotoxicity of PMNs stimulated by these lipid mediators in vitro and further support the immunomodulatory effects of HTS.

Current trends in resuscitation strategy for the multiply injured patient

The ideal resuscitation strategy for multiply injured patients remains a topic of ongoing debate. At present, no consensus has been reached on the ideal fluid for early resuscitation and on the threshold for blood product transfusions. The concept of "permissive hypotension" for bleeding trauma patients furthermore contributes to the controversy in the field, particularly as it relates to blunt trauma and to patients with associated head injuries. Finally, postinjury coagulopathy is a poorly defined entity, and current resuscitation strategies lack strong evidence-based scientific support. This review article provides a brief overview of the existing resuscitation protocols for multiply injured patients, including ATLS and "damage control", and will address developing controversies in the field.

Amantadine inhibits platelet-activating factor induced clathrin-mediated endocytosis in human neutrophils

Receptor signaling is integral for adhesion, emigration, phagocytosis, and reactive oxygen species production in polymorphonuclear neutrophils (PMNs). Priming is an important part of PMN emigration, but it can also lead to PMN-mediated organ injury in the host. Platelet-activating factor (PAF) primes PMNs through activation of a specific G protein-coupled receptor. We hypothesize that PAF priming of PMNs requires clathrin-mediated endocytosis (CME) of the PAF receptor (PAFr), and, therefore, amantadine, known to inhibit CME, significantly antagonizes PAF signaling. PMNs were isolated by standard techniques to >98% purity and tested for viability. Amantadine (1 mM) significantly inhibited the PAF-mediated changes in the cellular distribution of clathrin and the physical colocalization [fluorescence resonance energy transfer positive (FRET+)] of early endosome antigen-1 and Rab5a, known components of CME and similar to hypertonic saline, a known inhibitor of CME. Furthermore, amantadine had no effect on the PAF-induced cytosolic calcium flux; however, phosphorylation of p38 MAPK was significantly decreased. Amantadine inhibited PAF-mediated changes in PMN physiology, including priming of the NADPH oxidase and shape change with lesser inhibition of increases in CD11b surface expression and elastase release. Furthermore, rimantadine, an amantadine analog, was a more potent inhibitor of PAF priming of the N-formyl-methionyl-leucyl-phenylalanine-activated oxidase. PAF priming of PMNs requires clathrin-mediated endocytosis that is inhibited when PMNs are pretreated with either amantadine or rimantadine. Thus, amantadine and rimantadine have the potential to ameliorate PMN-mediated tissue damage in humans.

Therapeutic small-volume resuscitation preserves pancreatic microcirculation in acute experimental pancreatitis of graded severity in rats

BACKGROUND

Microcirculatory disorders play a major part in the pathogenesis of acute pancreatitis. Improvement of microcirculation is hypothesized to open a therapeutic window. The aim of this study was to evaluate the effects of small-volume resuscitation in acute pancreatitis.

METHODS

In rats, acute pancreatitis of graded severity was induced and pancreatic microcirculation was observed in vivo with an epiluminescent microscope. Primary outcome measures were microcirculation, leukocyte adherence, concentration of trypsinogen-activating peptide, amylase activity and histopathologic tissue damage.

RESULTS

In necrotizing pancreatitis patients receiving prophylactic intervention with 7.5% hypertonic saline the functional capillary density was 76%. Postcapillary venular leukocyte adherence was 45% of vein cross-section. The median histopathologic damage scored 8 points. In controls, a complete microcirculatory breakdown was observed, and in the group with therapeutic intervention no significant difference was detected. In intermediate pancreatitis, the number of perfused capillaries remained 55.0 versus 23.3% in controls. Leukocyte adherence was 40.0 versus 51.7%. The histopathologic damage scored 6.0 versus 9.0 points. Trypsinogen-activating peptide concentration was reduced to 164 versus 402 nM in controls. In cerulein pancreatitis, the number of perfused capillaries was equally preserved in both groups.

CONCLUSION

Small-volume resuscitation preserves capillary microcirculation and prevents pancreatic injury in intermediate necrotizing pancreatitis.

Hypertonic saline attenuates TNF-alpha-induced NF-kappaB activation in pulmonary epithelial cells

Resuscitation with hypertonic saline (HTS) attenuates acute lung injury (ALI) and modulates postinjury hyperinflammation. TNF-alpha-stimulated pulmonary epithelium is a major contributor to hemorrhage-induced ALI. We hypothesized that HTS would inhibit TNF-alpha-induced nuclear factor (NF)-kappaB proinflammatory signaling in pulmonary epithelial cells. Therefore, we pretreated human pulmonary epithelial cells (A549) with hypertonic medium (180 mM NaCl) for 30 min, followed by TNF-alpha stimulation (10 ng/mL). Key regulatory steps and protein concentrations in this pathway were assessed for significant alterations. Hypertonic saline significantly reduced TNF-alpha-induced intercellular adhesion molecule 1 levels and NF-kappaB nuclear localization. The mechanism is attenuated phosphorylation and delayed degradation of IkappaB alpha. Hypertonic saline did not alter TNF-alpha-induced p38 mitogen-activated protein kinase phosphorylation or constitutive vascular endothelial growth factor expression, suggesting that the observed inhibition is not a generalized suppression of protein phosphorylation or cellular function. These results show that HTS inhibits TNF-alpha-induced NF-kappaB activation in the pulmonary epithelium and, further, our understanding of its beneficial effects in hemorrhage-induced ALI.

Antinociception by neutrophil-derived opioid peptides in noninflamed tissue--role of hypertonicity and the perineurium

Inflammatory pain can be controlled by intraplantar opioid injection or by secretion of endogenous opioid peptides from leukocytes in inflamed rat paws. Antinociception requires binding of opioid peptides to opioid receptors on peripheral sensory nerve terminals. In the absence of inflammation, hydrophilic opioid peptides do not penetrate the perineurial barrier and, thus, do not elicit antinociception. This study was designed to examine the conditions under which endogenous, neutrophil-derived hydrophilic opioid peptides (i.e. Met-Enkephalin and beta-endorphin) can raise nociceptive thresholds in noninflamed tissue in rats. Intraplantar injection of the chemokine CXCL2/3 (macrophage inflammatory protein-2) induced selective neutrophil recruitment without overt signs of inflammation or changes in mechanical nociceptive thresholds (paw pressure threshold). Following intraplantar injection of hypertonic saline, the perineurial barrier was permeable for hours and intraplantar injection of opioid peptides increased mechanical nociceptive thresholds. While formyl-Met-Leu-Phe (fMLP) triggered opioid peptide release from neutrophils in vitro, nociceptive thresholds were unchanged in vivo. In vitro, hypertonicity interfered with fMLP-induced p38 mitogen activated kinase (MAPK) phosphorylation and opioid peptide release from neutrophils. These inhibitory effects were fully reversible by washout. In vivo, return to normotonicity occurred within 30min while the perineurium remained permeable for hours. Under these conditions, fMLP triggered MAPK phosphorylation and induced opioid peptide-mediated increases in nociceptive thresholds in the noninflamed paw. Taken together, antinociception mediated by endogenous opioids in noninflamed tissue has two important requirements: (i) opening of the perineurial barrier for opioid peptide access and (ii) opioid peptide release from neutrophils involving p38 MAPK.

Hypertonic saline resuscitation from hemorrhagic shock does not impair the neutrophil response to intraabdominal infection

BACKGROUND

Hypertonic saline (HTS) has been proposed as a resuscitation strategy following trauma based on its ability to prevent organ dysfunction by exerting immunosuppressive effects on inflammatory cells, including neutrophils. Because these cells are central to the innate response to bacteria, we hypothesized that hypertonic treatment for hemorrhagic shock might alter the host response to bacterial contamination of the peritoneal cavity and therefore render the host more susceptible to invasive infection.

METHODS

Male Sprague-Dawley rats were subjected to hemorrhagic shock and resuscitated with either lactated Ringer solution (RL) or HTS. After intraperitoneal injection of feces, Escherichia coli, or lipopolysaccharide, peritoneal neutrophil accumulation and bacterial clearance were studied. In some studies, lipopolysaccharide as an inflammatory stimulus was injected into both the peritoneal cavity and the lungs.

RESULTS

Peritoneal neutrophil accumulation in response to each of the stimuli did not differ between RL- and HTS-resuscitated animals. Whereas emigration into the peritoneum activated neutrophils, there was no difference between resuscitation strategies, consistent with the finding that bacterial clearance did not differ between groups. Although peritoneal neutrophil sequestration was unaffected by resuscitation type, HTS still was able to prevent lung neutrophil accumulation compared to RL treatment.

CONCLUSIONS

HTS resuscitation did not impair the host response to bacterial contamination of the peritoneal cavity. However, the ability of HTS to prevent lung neutrophil accumulation in this setting persisted. These findings suggest that peritoneal bacterial contamination should not be considered a contraindication to the use of HTS in the trauma setting associated with hemorrhagic shock.

Therapeutic effects of hypertonic saline on peritonitis-induced septic shock with multiple organ dysfunction syndrome in rats

OBJECTIVE

Significant mortality in patients with sepsis results from the development of multiple organ dysfunction syndrome. Small-volume resuscitation with 7.5% NaCl hypertonic saline has been proposed to restore physiologic hemodynamics in hemorrhagic shock. Therefore, we hypothesized that hypertonic saline resuscitation could alleviate the development of multiple organ dysfunction syndrome in sepsis induced by cecal ligation and puncture.

DESIGN

Randomized, prospective animal experiment.

SETTING

Academic research laboratory.

SUBJECTS

Male Wistar rats.

INTERVENTIONS

The animals were randomly allocated to one of four groups: 1) sham operation (0.9% NaCl, 4 mL/kg intravenously, at 3 hrs after laparotomy); 2) sham operation plus hypertonic saline (7.5% NaCl, 4 mL/kg intravenously, at 3 hrs after laparotomy); 3) cecal ligation and puncture (0.9% NaCl, 4 mL/kg intravenously, at 3 hrs after cecal ligation and puncture); and 4) cecal ligation and puncture plus hypertonic saline (7.5% NaCl, 4 mL/kg intravenously, at 3 hrs after cecal ligation and puncture).

MEASUREMENTS AND MAIN RESULTS

Cecal ligation and puncture for 18 hrs was associated with circulatory failure (i.e., hypotension and vascular hyporeactivity to norepinephrine), multiple organ dysfunction syndrome (examined by biochemical variables and histologic studies), and 18-hr mortality. Hypertonic saline not only ameliorated the deterioration of hemodynamic changes but also attenuated neutrophil infiltration in the lung and the liver of septic animals. Hypertonic saline increased the survival rate at 9 and 18 hrs compared with the cecal ligation and puncture group. Moreover, hypertonic saline reduced plasma nitric oxide and interleukin-1beta and organ O2-* levels in rats that underwent cecal ligation and puncture.

CONCLUSIONS

Hypertonic saline prevented circulatory failure, alleviated multiple organ dysfunction syndrome, and decreased the mortality rate in animals receiving cecal ligation and puncture. These beneficial effects of hypertonic saline may be attributed to reducing the plasma concentration of nitric oxide and interleukin-1beta as well as the organ O2-* level and decreasing lung neutrophil infiltration and liver necrosis. Our study suggests that hypertonic saline could be a potential and inexpensive therapeutic agent in the early sepsis of animals or patients.

Chloride movements in human neutrophils during phagocytosis: characterization and relationship to granule release

Chloride ion efflux is an early event occurring after exposure of human neutrophils to several soluble agonists. Under these circumstances, a rapid and reversible fall in the high basal intracellular chloride (Cl-i) levels is observed. This event is thought to play a crucial role in the modulation of several critical neutrophil responses including activation and up-regulation of adhesion molecules, cell attachment and spreading, cytoplasmic alkalinization, and activation of the respiratory burst. At present, however, no data are available on chloride ion movements during neutrophil phagocytosis. In this study, we provide evidence that phagocytosis of Candida albicans opsonized with either whole serum, complement-derived opsonins, or purified human IgG elicits an early and long-lasting Cl- efflux accompanied by a marked, irreversible loss of Cl-i. Simultaneous assessment of Cl- efflux and phagocytosis in cytochalasin D-treated neutrophils indicated that Cl- efflux occurs without particle ingestion. These results suggest that engagement of immune receptors is sufficient to promote chloride ion movements. Several structurally unrelated chloride channel blockers inhibited phagocytosis-induced Cl- efflux as well as the release of azurophilic-but not specific-granules. It implicates that different neutrophil secretory compartments display distinct sensitivity to Cl-i modifications. Intriguingly, inhibitors of Cl- exchange inhibited cytosolic Ca2+ elevation, whereas Cl- efflux was not impaired in Ca2+-depleted neutrophils. We also show that FcgammaR(s)- and CR3/CR1-mediated Cl- efflux appears to be dependent on protein tyrosine phosphorylation but independent of PI3K and phospholipase C activation.

Sodium chloride inhibits cytokine production by lipopolysaccharide-stimulated human neutrophils and mononuclear cells

Hypertonic sodium chloride (NaCl) solution has been shown to have beneficial effects on patients with hypovolemic shock. Therapy with hypertonic saline seems to neutralize or minimize the deleterious immune responses in these patients. In this study, we addressed how hypertonic NaCl solution affects the release of cytokines by isolated human blood cells. We examined the effect of NaCl on tumor necrosis factor (TNF)-alpha, interleukin (IL)-8, IL-1beta, and IL-1 receptor antagonist released by human neutrophils and mononuclear cells under nonstimulated and LPS-stimulated conditions. Cells isolated from healthy donors were cultured in the presence or absence of lipopolysaccharide (LPS). Cytokine concentrations were measured by enzyme-linked immunosorbent assay in culture supernatants. The addition of NaCl lowered the production of IL-8, TNF-alpha, and IL-1 receptor antagonist by neutrophils, and IL-8 and IL-1beta by mononuclear cells stimulated with LPS. This effect was not observed when NaCl solution was replaced by a solution of potassium iodide in the same conditions. The decreased production of cytokines in the presence of hypertonic saline was not caused by cell death. Our findings support the proposal that the modulation of leukocyte inflammatory response by NaCl occurs by an electrolyte-specific effect in addition to the hyperosmolarity. Furthermore, the results of this study support the therapeutic use of appropriate doses of i.v. NaCl solutions to minimize tissue injury characterized by neutrophil and mononuclear cell infiltration into tissues in post-traumatic patients.

Hypertonic saline: a clinical review

Literature suggest that hypertonic saline (HTS) solution with sodium chloride concentration greater than the physiologic 0.9% can be useful in controlling elevated intracranial pressure (ICP) and as a resuscitative agent in multiple settings including traumatic brain injury (TBI). In this review, we discuss HTS mechanisms of action, adverse effects, and current clinical studies. Studies show that HTS administered during the resuscitation of patients with a TBI improves neurological outcome. HTS also has positive effects on elevated ICP from multiple etiologies, and for shock resuscitation. However, a prospective randomized Australian study using an aggressive resuscitation protocol in trauma patients showed no difference in amount of fluids administered during prehospital resuscitation, and no differences in ICP control or neurological outcome. The role of HTS in prehospital resuscitation is yet to be determined. The most important factor in improving outcomes may be prevention of hypotension and preservation of cerebral blood flow. In regards to control of elevated ICP during the inpatient course, HTS appears safe and effective. Although clinicians currently use HTS with some success, significant questions remain as to the dose and manner of HTS infusion. Direct protocol comparisons should be performed to improve and standardize patient care.

Infusion of Hypertonic Saline (7.5%) Does Not Change Neutrophil Oxidative Burst or Expression of Endothelial Adhesion Molecules After Abdominal Hysterectomy

BACKGROUND

Previous studies found hypertonicity to affect neutrophils in intact laboratory animals and in human blood cell cultures. We investigated whether infusion of hypertonic saline in a clinical relevant dose before hysterectomy affected peripheral blood neutrophils and their response to surgery.

METHODS

Fifteen women scheduled for open abdominal hysterectomy were randomized double-blindly to infusion of 4 mL/kg 7.5% NaCl, 4 mL/kg 0.9% NaCl, or 32 mL/kg 0.9% NaCl over 20 minutes. Blood was collected at baseline, after infusion, 1, 4, and 24 hours postoperatively for the determination of leukocyte and differential count, neutrophil membrane expression of endothelial adhesion molecules by flow cytometry, and O2- -generation by superoxide dismutase-inhibitable reduction of cytochrome C.

RESULTS

Surgery induced well-known changes in the number and distribution of white blood cells, reduced the expression of adhesion molecules, and halved the superoxide production unrelated to the tonicity or volume of the infused fluids.

CONCLUSION

Infusion of a clinically relevant dose of hypertonic saline has no detectable effect on the membrane expression of endothelial adhesion molecules or O2- -generation in circulating neutrophils after elective abdominal hysterectomy.

An early bolus of hypertonic saline hydroxyethyl starch improves long-term outcome after global cerebral ischemia

OBJECTIVE

The beneficial effect of hypertonic saline solutions in the emergency treatment of shock and traumatic brain injury is well described. The present study determines effects of a single bolus of hypertonic saline on long-term survival, neurologic function, and neuronal survival 10 days after global cerebral ischemia. In addition, we evaluated the therapeutic window for hypertonic saline treatment (early vs. delayed application).

DESIGN

Laboratory experiment.

SETTING

University laboratory.

SUBJECTS

Male Wistar rats weighing 240-330 g.

INTERVENTIONS

Rats were submitted to temporal global cerebral ischemia using temporary bilateral carotid occlusion combined with hypobaric hypotension. Animals received 7.5% saline/6% hydroxyethyl starch (HHS) or vehicle (NaCl 0.9%) at either 1.5 mins (early treatment) or 31.5 mins (delayed treatment) of reperfusion. Regional cerebral blood flow (rCBF) and physiologic variables were measured during insult and early reperfusion. Animal survival and neurologic function were evaluated throughout the 10-day observation period. Quantification of brain injury was performed on day 10.

MEASUREMENTS AND MAIN RESULTS

Early treatment with HHS resulted in a robust restoration of rCBF after ischemia, reduced postischemic mortality by 77% (9% vs. 39% in vehicle-treated controls), ameliorated neurologic performance (Neuro-Deficit-Score 10 days after insult, 96 +/- 0.7 vs. 85 +/- 1.4, mean +/- se), and almost blunted neuronal cell death (hippocampal CA1, 2150 +/- 191 vs. 884 +/- 141 neurons/mm; cortex, 1746 +/- 91 vs. 1060 +/- 112). In contrast, delayed treatment resulted in no sustained effects.

CONCLUSIONS

Timing of HHS treatment is critical after experimental global cerebral ischemia to reduce mortality, improve neurologic function, and neuronal survival. Our results suggest that early application of HHS may be a potential neuroprotective strategy after global cerebral ischemia.

A single bolus of 3% hypertonic saline with 6% dextran provides optimal initial resuscitation after uncontrolled hemorrhagic shock

BACKGROUND

The optimal fluid for early resuscitation of hemorrhagic shock would restore perfusion without increasing blood loss, hypothermia, acidosis, or coagulopathy. This study examined effects of a single bolus of hypertonic saline (HTS) with or without (+/-) dextran (D) after uncontrolled hemorrhage (UH) and determined optimal fluid composition.

METHODS

Fifty swine were anesthetized and underwent invasive line placement, celiotomy, splenectomy, suprapubic catheterization, and grade V liver injury. After 30 minutes of UH, blinded fluid resuscitation was initiated with a 250-mL bolus. Animals were randomized to five groups: normal saline (NS), 3% HTS (3%), 3% HTS/6% D (3% D), 7.5% HTS (7.5%), or 7.5% HTS/6% D (7.5% D). Mean arterial pressure (MAP) and tissue oxygen saturation (StO2) were recorded. Laboratory and thrombelastography (TEG) data were collected every 30 minutes. Animals were sacrificed 120 minutes after injury. Analysis of variance was used to compare groups. Significance was defined as p < 0.05.

RESULTS

Baseline characteristics and laboratory values were similar in all groups. All groups achieved a similar degree of shock. Two NS and two 3% animals did not survive to 120 minutes. Fluids containing dextran produced a significantly greater increase in MAP (p < 0.02). Animals receiving 3% D maintained a higher MAP 90 minutes after fluid bolus. Also, 7.5% +/- D produced a significantly greater initial increase in StO2 (p < 0.05). This effect declined after fluid bolus while 3% D continued to improve tissue oxygenation. Significant differences developed between groups in TEG values, hematocrit, fibrinogen, urine sodium, serum sodium, serum chloride, and urine output.

CONCLUSIONS

A single bolus of 3% D after uncontrolled hemorrhagic shock produces an adequate and sustained rise in MAP and StO2 and attenuates hypercoagulability. Resuscitation with 7.5% +/- D produces significantly increased urine output accompanied by a decline in MAP and StO2 over time. A single bolus of 7.5% D results in significant dilutional anemia and relative hypofibrinogenemia.

HSPTX protects against hemorrhagic shock resuscitation-induced tissue injury: an attractive alternative to Ringer's lactate

BACKGROUND

Conventional fluid resuscitation with Ringer's lactated (RL) activates neutrophils and causes end-organ damage. We have previously shown that HSPTX, a combination of small volume hypertonic saline (HS) and pentoxifylline (PTX), a phosphodiesterase-inhibitor, downregulates in vitro neutrophil activation and proinflammatory mediator synthesis. Herein, we hypothesized that HSPTX decreases end-organ injury when compared with RL in an animal model of hemorrhagic shock.

METHODS

Sprague-Dawley rats were bled to a mean arterial pressure of 35 mm Hg for 1 hour. Animals were divided into 3 groups: sham (no shock, no resuscitation, n = 7), RL (32 mL/kg, n = 7), and HSPTX (7.5% NaCl 4 mL/kg + PTX 25 mg/kg; n = 7). Shed blood was infused after fluid resuscitation. Blood pressure was monitored until the end of resuscitation. Animals were sacrificed at 24 hour after resuscitation. Bronchoalveolar lavage fluid (BALF) was obtained for white cell count (total and differential) and TNF-alpha and IL-1beta levels were measured by ELISA. Lung and intestinal injury at 24 hour were evaluated by histopathology. Organ damage was graded by a pathologist and a score was created (0 = no injury; 3 = severe). Lung neutrophil infiltration was evaluated by MPO immune staining.

RESULTS

There were no differences in mean arterial pressure between groups. At 24 hours, BALF leukocyte count was decreased by 30% in HSPTX animals (p < 0.01). TNF-alpha and IL-1beta levels were markedly decreased in HSPTX-resuscitated animals compared with their RL counterparts (p < 0.01). HSPTX-resuscitated animals (lung injury score = 1.0 +/- 0.4) had markedly decreased acute lung injury compared with RL-treated animals (2.5 +/- 0.3) (p < 0.01). RL resuscitation led to a two-fold increase in lung neutrophil infiltration whereas in HSPTX-treated animals, the number of MPO + cells was similar to sham animals (p < 0.001). Intestinal injury was markedly attenuated by HSPTX (1.1 +/- 0.3) compared with RL animals (2.6 +/- 0.4) (p < 0.001).

CONCLUSIONS

HSPTX, a small volume resuscitation strategy with marked immunomodulatory potential led to a marked decrease in end-organ damage. HSPTX is an attractive alternative to RL in hemorrhagic shock resuscitation.

Local and systemic effects of hypertonic solution (NaCl 7.5%) in experimental acute pancreatitis

OBJECTIVES

Severe acute pancreatitis (AP) is characterized by hemodynamic alterations and a systemic inflammatory response, leading to a high mortality rate. Treatment of hemorrhagic shock with hypertonic saline solutions significantly reduces mortality through an improvement in the hemodynamic conditions and possibly by an anti-inflammatory effect. Therefore, hypertonic solutions could be effective in AP.

METHODS

Wistar rats were divided in 4 groups: group C, control, without AP; group NT, AP, without treatment; group NS, treatment with normal saline solution (NaCl 0.9%) 1 hour after AP; group HTS, treatment with hypertonic saline solution (NaCl 7.5%) 1 hour after AP. AP was induced by injection of 2.5% sodium taurocholate into the pancreatic duct. Mean arterial blood pressure (MAP) and heart rate were recorded at 0 and 2, 4, 24, and 48 hours after AP. After induction of AP, animals were killed at 2, 12, 24, and 48 hours for serum amylase, interleukin (IL)-6, and IL-10 analysis, pancreatic tissue culture and histologic analysis, oxidation and phosphorylation of liver mitochondria, pulmonary myeloperoxidase activity (MPO), and mortality study.

RESULTS

In animals of groups NS and NT, a significant decrease of MAP was observed 48 hours after AP (NS: 91 +/- 3 mm Hg; NT: 89 +/- 3 mm Hg) compared with baseline (C: 105 +/- 2 mm Hg) and to HTS group (HTS: 102 +/- 2 mm Hg; P < 0.05). In animals of group NT, NS, and HTS, serum IL-6 and IL-10 levels were significantly higher at 2 hours after AP compared with the control group. However, IL-6 levels at 12 hours after AP and IL-10 levels at 2 and 12 hours after AP were significant lower in group HTS compared with NS and NT groups (P < 0.05). In group HTS, a decrease of pulmonary MPO activity and of pancreatic infection was observed 24 hours after AP compared with NT and NS groups (P < 0.05). A significant reduction on pancreatic acinar necrosis and mitochondrial dysfunction was observed after 48 hours of AP in animals of group HTS compared with groups NT and NS (P < 0.05). A significant reduction on mortality was observed in HTS (0/14) compared with NS (6/17; 35%) and NT (7/20; 35%).

CONCLUSIONS

The administration of hypertonic saline solution in experimental AP attenuated hemodynamic alterations, decreased inflammatory cytokines, diminished systemic lesions and pancreatic acinar necrosis, prevented pancreatic infection, and reduced the mortality rate.

Hypertonic saline enhances neutrophil elastase release through activation of P2 and A3 receptors

Hypertonic saline (HS) holds promise as a novel resuscitation fluid for the treatment of trauma patients because HS inhibits polymorphonuclear neutrophil (PMN) activation and thereby prevents host tissue damage and associated posttraumatic complications. However, depending on conditions of cell activation, HS can increase PMN degranulation, which could exacerbate tissue damage in trauma victims. The cellular mechanism by which HS increases degranulation is unknown. In the present study, we tested whether HS-induced ATP release from PMN and feedback via P1 and/or P2 receptors may be involved in the enhancement of degranulation by HS. We found that HS enhances elastase release and ERK and p38 MAPK activation when HS is added after activation of PMN with formyl peptide (fMLP) or phorbol ester (PMA). Agonists of P2 nucleotide and A3 adenosine receptors mimicked these enhancing effects of HS, whereas antagonists of A3 receptors or removal of extracellular ATP with apyrase diminished the response to HS. A1 adenosine receptor antagonists increased the enhancing effect of HS, whereas A1 receptor agonists inhibited elastase release. These data suggest that HS upregulates degranulation via ATP release and positive feedback through P2 and A3 receptors. We propose that these feedback mechanisms can serve as potential pharmacological targets to fine-tune the clinical effectiveness of HS resuscitation.

HYPERTONIC SALINE MODULATES INNATE IMMUNITY IN A MODEL OF SYSTEMIC INFLAMMATION

We sought to determine if hypertonic saline (HTS) impacted alveolar macrophage (AM) activation and intracellular inflammatory gene signaling in a model of systemic inflammation. Rats received an intravenous administration of 4 mL/kg of 7.5% HTS or L-lactate lactated Ringer's (L-LR). They were simultaneously treated with an intraperitoneal injection of zymosan, which induces noninfectious systemic inflammation. AM were harvested by bronchoalveolar lavage 24 h after treatment. AM activation was analyzed by measurement of baseline and lipopolysaccharide (LPS)-induced TNF-alpha production. Intracellular signaling was analyzed for activation of the mitogen-activated protein kinases (MAPKs): ERK1/2, JNK, and p38. AM from HTS-treated rats produced less TNF-alpha than from L-LR-treated rats (927 +/- 335 pg/mL [SEM] vs. 3628 +/- 783 pg/mL [SEM], P = 0.001) and were also less responsive to LPS (4444 +/- 86 pg/mL [SEM] vs. 6666 +/- 91 pg/mL [SEM], P = 0.058). However, there was no difference in MAPK activation. In vivo HTS prevents excessive AM activation during systemic inflammation. This suppression is mediated through alternate pathways and does not induce the classic MAPK signaling cascade.

Osmotic regulation of cell function and possible clinical applications

Inflammation and immunosuppression can cause acute respiratory distress syndrome, multiple organ failure, and sepsis, all of which are lethal posttraumatic complications in trauma patients. Prevention of the inflammation and immunosuppression has been a main focus of trauma researcher for many years. Recently, hypertonic resuscitation has attracted attention as a possible therapeutic approach to counteract such deleterious immune responses in trauma patients. We have begun to understand how hypertonic fluids affect immune cell signaling, and a number of experimental and clinical studies have started to reveal valuable information on the clinical efficacy and the limitations of hypertonic resuscitation fluids. Knowledge of how osmotic cues regulate immune cell function will enable us to fully exploit the clinical potential of hypertonic resuscitation to reduce inflammatory and anergic complications in trauma patients.

Immune effect of hypertonic saline: fact or fiction?

Hypertonicity affects many parts of the immune system. Animal studies and experiments in isolated cell cultures show that hypertonicity reversibly suppresses several neutrophil functions and at the same time up-regulates T-lymphocyte function. Infusion of hypertonic saline with or without colloids may thus, besides providing efficient plasma volume expansion, ameliorate the detrimental consequences on the immune function of trauma, shock, reperfusion, and major surgery. However, the few clinical studies conducted to date, specifically addressing the immune effect of hypertonic saline infusion, have shown little, if any, effect on markers of immune function, and larger clinical trials have not demonstrated benefit in terms of morbidity or mortality. Thus, as opposed to animal and cell-culture studies, the immune-modulating properties of hypertonic saline infusion would appear to be of limited value in clinical practice. This review presents in vitro studies, animal experiments, and clinical trials which investigated the consequences of hypertonic saline on markers of immune function.

Effect of different resuscitation strategies on neutrophil activation in a swine model of hemorrhagic shock

Activated neutrophils play a pivotal role in resuscitation injury. The strategies used for resuscitation (types of fluids and methods of administration) can affect the degree of neutrophil activation. The aim of this study was to test the commonly available resuscitation fluids in a large animal model of hemorrhagic shock to determine the strategy associated with the least degree of neutrophil activation.

METHODS

Female swine (n=63, weight 45-60 kg) were anesthetized using isoflurane and catheters were placed for hemodynamic monitoring. After 120 min, they were subjected to a volume controlled hemorrhage (28 ml/kg) over 15 min, kept in shock for 60 min, and then resuscitated. The resuscitation groups were as follows: (1) anesthesia only (n=5); (2) hemorrhage, sham resuscitation (n=5); (3) LR-fast rate 3x blood loss (n=6); (4) LR slow rate-3x blood loss (n=6); (5) LR low volume-1x blood loss (n=6); (6) Dextran 40-1x blood loss (n=6); (7) 6% hetastarch-1x blood loss (n=6); (8) 5% albumin-1x blood loss (n=6); (9) 25% albumin-1/5x blood loss (n=6); (10) whole blood resuscitation-1x blood loss (n=6); (11) 7.5% hypertonic saline (HTS)-0.3x blood loss (n=5). Resuscitation fluids were infused over 1 h in all groups except group 4 (LR slow rate, which was over 3 h). Animals were observed for 180 min following the resuscitation period. Neutrophil oxidative burst activity was determined in whole blood using flow cytometery.

RESULTS

Animals resuscitated with dextran and hetastarch showed significantly (P<0.05) higher neutrophil burst activity. Resuscitation with LR also caused neutrophil activation (P<0.05), and the highest degree of activation was seen when a large volume of LR was given at a fast rate (group 8). However, all LR infusion protocols were associated with significant neutrophil activation compared with anesthesia (group 1) or sham resuscitation (group 2). No significant activation was seen in the animals resuscitated with albumin or fresh whole blood.

CONCLUSION

Artificial colloids and LR (independent of rate or volume of infusion) caused significant neutrophil activation, which was not seen with albumin and whole blood resuscitation. These findings suggest that the type of resuscitation fluid and method of infusion can influence neutrophil function.

Infusion of hypertonic saline (7.5% NaCl) causes minor immunological changes in normovolaemic women

BACKGROUND

Haemorrhagic shock is treated effectively by infusion of hypertonic saline/colloid solutions. Furthermore, previous studies found hypertonicity to affect immune responses in animals and in human blood cell cultures. It is unknown, however, whether hypertonic saline infusion affects immune responses in humans.

METHODS

In a randomized double-blind study, we infused 4 ml kg-1 of 7.5% NaCl or 0.9% NaCl over 10 min in 20 fasting women before hysterectomy. We collected peripheral blood at baseline, 30, and 120 min after start of the infusion and before surgery for the determination of leucocyte and differential count; lymphocyte subtypes; neutrophil chemotaxis; elastase concentration; and the cytokine's tumour necrosis factor-alpha (TNFalpha), interleukin (IL)-1beta, IL-6, IL-8, IL-1 receptor antagonist (IL-1ra), and IL-10. Phytohaemagglutinin (PHA)-induced lymphocyte proliferation and natural killer cell cytotoxicity were measured before and 120 min after infusion.

RESULTS

Compared with normal saline, infusion of hypertonic saline temporarily increased the number of B cells in peripheral blood (P < 0.01); increased the concentration of plasma elastase, a marker of neutrophil degranulation (P < 0.05); and decreased the number of circulating neutrophils (P < 0.001). No other effects were detected in the measured immunological parameters.

CONCLUSION

The immunological consequences of hypertonic saline infusion seem to be modest and are unlikely to cause any clinical effects, at least in normovolaemic women.

cDNA profiling in leukocytes exposed to hypertonic resuscitation fluids

BACKGROUND

Resuscitative fluids induce distinctive changes in leukocyte functions: incubation with colloid Dextran increases production of reactive oxygen species and adhesion, whereas exposure to hypertonic saline (HTS) inhibits "oxidative burst" and phagocytosis. In hypertonic saline Dextran (HTD), the hypertonic component determines the leukocyte functional behavior and subsequently activation response. We investigated whether leukocyte gene expression is analogously affected.

METHODS

Whole blood from eight volunteers was diluted and incubated for 30 min at 37(o)C in 6.0% Dextran-70, 7.5% HTS, and 7.5% HTD. Total leukocyte RNA was extracted and used to synthesize biotinylated cDNA probes. Each probe was individually hybridized to a cDNA array to simultaneously measure the expression of 23 genes involved in inflammation, cell migration, and apoptosis.

RESULTS

Leukocytes incubated with Dextran-70 demonstrated greater than a 6-fold (p < 0.05) increase in the expression of interleukin-8, growth-regulated oncogenes alpha and beta, L-selectin, superoxide dismutase, tumor necrosis factor-alpha (TNF-alpha), and mitogen-activated protein kinase 3. The expression profile induced by HTS was not significantly different from that of unstimulated blood, except for prominent induction of only three genes. HTD attenuated the expression of Dextran-70 upregulated genes, although the level of their expression was higher than in HTS-treated leukocytes.

CONCLUSIONS

Hypertonic resuscitation fluids diminish the expression of immune activation-associated genes. Hypertonic component of HTD determines the leukocyte gene expression profile.

Clinically relevant hypertonicity prevents stored blood- and lipid-mediated delayed neutrophil apoptosis independent of p38 MAPK or caspase-3 activation

BACKGROUND

Delayed apoptosis of primed neutrophils (PMNs) may facilitate PMN-mediated tissue injury leading to postinjury multiple organ failure. Aged (42-day-old) stored red blood cells (RBC42) delay PMN apoptosis through proinflammatory phospholipids such as platelet-activating factor (PAF) and lyso-phosphatidylcholine (LPC). Hypertonic saline (HTS) attenuates PMN cytotoxic functions. We hypothesized that clinically relevant HTS would provoke PMN apoptosis, as well as prevent stored blood- and lipid-mediated delayed PMN apoptosis through activation of p38 mitogen-activated protein kinase (MAPK) and caspase-3.

METHODS

PMNs harvested from healthy volunteers were incubated (5% CO(2), 37 degrees C, 24 hr) with RBC42 plasma, PAF (20 microM), or LPC (4.5 microM), with or without the p38 MAPK inhibitor SB 203580, the caspase-3 inhibitor zDEVD-fmk (10 micromol/L) or the pan-caspase inhibitor zVAD-fmk (20 micromol/L). Duplicate samples were preincubated in HTS (Na [180 mM]). Apoptotic index (% PMNs undergoing apoptosis) was assessed morphologically. p38 MAPK activation was assessed by Western blotting. Caspase-3 activity was measured colorimetrically.

RESULTS

PAF, LPC, and RBC42 plasma delayed apoptosis; HTS increased apoptosis compared with controls. HTS prevented PAF, LPC, and RBC42-delayed apoptosis. p38 MAPK was not activated by HTS; its inhibition had no effect on the actions of HTS. Caspase inhibition attenuated the ability of HTS to increase apoptosis, but it did not affect the ability of HTS to restore healthy PMN apoptosis in the presence of RBC42.

CONCLUSION

HTS increases PMN apoptosis and prevents stored blood- and lipid-mediated delayed PMN apoptosis. HTS may activate caspase-3, but alternative signaling pathways appear to be involved in modulating the effects of lipids on PMN apoptosis.

Effect of hypertonic saline on microvascular permeability in the activated endothelium

INTRODUCTION

The effect of hypertonic saline (HTS) on microvascular permeability in microvessels with activated endothelial cells is unclear. We hypothesized that HTS and HTS with dextran would decrease hydraulic permeability after activation of the endothelium.

METHODS

Hydraulic permeability (L(p)) was measured in rat mesenteric venules using the modified Landis micro-occlusion technique. The effects of 185 mM HTS and HTS plus 2% dextran (HSD) were tested in the activated endothelium by measuring L(p) at baseline, after perfusion with ATP, and again after HTS (n = 6) or HSD (n = 6). ATP (10 microM) activated endothelial cells and increased L(p) 4-fold. Additional venules were used to test the effects of 135 mM NaCl (n = 6) and 235 mM (n = 6) NaCl after endothelial activation with ATP.

RESULTS

After endothelial activation with ATP, L(p) values were 6.05 +/- 1.63. Subsequent perfusion with HTS decreased L(p) to 2.05 +/- 0.52 (P = 0.01). In the HSD trails, L(p) values after ATP were 6.17 +/- 1.38. Perfusion with HSD decreased L(p) to 1.65 +/- 0.30 (P = 0.001). After endothelial activation, 135 mM NaCl had no effect on L(p); however, 185 mM NaCl decreased L(p) 3-fold and 235 mM NaCl decreased L(p) 6-fold. Units for L(p) are x10(-7) cm - s(-1). cmH(2)O(-1).

CONCLUSIONS

Both HTS and HSD decreased hydraulic permeability after endothelial activation. These findings suggest that HTS may decrease microvascular fluid loss during states of elevated microvascular leak. In addition to the ability of hypertonic solutions to withdraw intracellular water to increase plasma volume, these findings propose an endothelial barrier mechanism whereby HTS and HSD act to maintain intravascular volume.

Fluid resuscitation: the target from an analysis of trauma systems and patient survival

Much can be learned from studying the deaths that occur in trauma systems as they have developed. Understanding these deaths and the potential effect of trauma systems on reducing death has major implications for designing clinical trials in fluid resuscitation. The availability of new, exciting information regarding fluid composition and physiologic effects argues for new, better-designed clinical trials. By agreeing on the form of resuscitation trials in the future, we will increase our ability to see clinically significant differences in outcome as we move from animal data to clinical efficacy.

Dextran modulates microvascular permeability: effect in isotonic and hypertonic solutions

Hypertonic saline solutions with Dextran (HSD) have been advocated for rapid restoration of intravascular volume. Dextran is thought to increase the duration of action of hypertonic saline (HS) by selectively partitioning the water in the vascular space that has been drawn out of cells by HS. The goal of this study was to define the microvascular permeability modulating activity of Dextran in both isotonic and hypertonic solutions. We hypothesized that Dextran would decrease hydraulic permeability (Lp). Using the modified Landis micro-occlusion technique, single rat mesenteric venules were perfused with either normal Ringers (NR) with 135 mM NaCl or HS with 185 mM NaCl. In sequential cannulations of the venules, 1%, 2%, and 3% of Dextran was added to the NR perfusion (n = 6) and the HS perfusion (n = 6). The Lp was measured at baseline and after perfusion with each Dextran concentration. Baseline Lp measurements for NR and HS solutions were 1.01 +/- 0.034 and 5.14 +/- 1.02, respectively. In the NR group, the 2% and 3% Dextran decreased permeability below baseline levels to 0.79 +/- 0.028 (P < 0.0001) and 0.66 +/- 0.028 (P < 0.0001), respectively. In the HS group, the 2% and 3% Dextran decreased permeability to 1.65 +/- 0.53 (P < 0.0001) and 0.99 +/- 0.2 (P < 0.0001), respectively. All values for Lp are x10(-7) cm s(-1) x cm H2O(-1). The addition of Dextran to isotonic and hypertonic solutions results in a decrease in microvessel permeability. This effect is more pronounced with the perfusion of hypertonic solutions. The results demonstrate the oncotic potential of Dextran and its ability to hold water in the vascular space. Dextran may have a beneficial effect when used for resuscitation with HS by decreasing microvascular permeability and augmenting intravascular volume.

Hypertonic saline resuscitation attenuates neutrophil lung sequestration and transmigration by diminishing leukocyte-endothelial interactions in a two-hit model of hemorrhagic shock and infection

BACKGROUND

Hypertonic saline (HTS) attenuates polymorphonuclear neutrophil (PMN)-mediated tissue injury after hemorrhagic shock. We hypothesized that HTS resuscitation reduces early in vivo endothelial cell (EC)-PMN interactions and late lung PMN sequestration in a two-hit model of hemorrhagic shock followed by mimicked infection.

METHODS

Thirty-two mice were hemorrhaged (40 mm Hg) for 60 minutes and then given intratracheal lipopolysaccharide (10 microg) 1 hour after resuscitation with shed blood and either HTS (4 mL/kg 7.5% NaCl) or Ringer's lactate (RL) (twice shed blood volume). Eleven controls were not manipulated. Cremaster intravital microscopy quantified 5-hour EC-PMN adherence, myeloperoxidase assay assessed lung PMN content (2 1/2 and 24 hours), and lung histology determined 24-hour PMN transmigration.

RESULTS

Compared with RL, HTS animals displayed 55% less 5-hour EC-PMN adherence (p = 0.01), 61% lower 24-hour lung myeloperoxidase ( p= 0.007), and 57% lower mean 24-hour lung histologic score ( p= 0.027).

CONCLUSION

Compared with RL, HTS resuscitation attenuates early EC-PMN adhesion and late lung PMN accumulation in hemorrhagic shock followed by inflammation. HTS resuscitation may attenuate PMN-mediated organ damage.

Hyperosmolarity abrogates neutrophil cytotoxicity provoked by post-shock mesenteric lymph

Hypertonic saline (HTS) resuscitation inhibits acute lung injury in animal models of shock, but some argue this may simply represent more efficient fluid resuscitation. Inflammatory mediators within mesenteric lymph have been identified as a link between splanchnic hypoperfusion and acute respiratory distress syndrome (ARDS). We hypothesize that HTS resuscitation abrogates post-shock lymph-mediated neutrophil (PMN) priming and PMN-mediated human endothelial cell cytotoxicity. Mesenteric lymph was collected from rats (n = 5) before (control), during non-lethal hemorrhagic shock, defined as a mean arterial pressure (MAP) of 40 mmHg for 30 min, and after resuscitation (shed blood + 2 x lactated Ringers (LR) versus 7.5% NaCl, 4 cc/kg, over 5 min). Isolated human PMNs were primed with physiologic concentrations (5% v:v) of lymph either from animals resuscitated with LR or HTS and activated with either PMA or fMLP. In a separate set of experiments, human PMNs were primed with LR lymph after incubation with HTS (180 mM NaCl). The maximal rate of superoxide production was measured by reduction of cytochrome C. In addition, the effect of HTS pretreatment on PMN adherence to human pulmonary microvascular endothelial cells (HMVEC) and PMN-mediated cytotoxicity was determined after lymph-mediated PMN priming. PHSML primed isolated PMNs above buffer controls and pre-shock lymph in a normotonic environment; HTS resuscitation abrogated this effect. HTS preincubation of isolated PMNs inhibited PHSML-induced PMN priming, adherence to HMVECs, and PMN-mediated HMVEC cytotoxicity. Hypertonic resuscitation (HTS) abrogates PHSML pniming of the PMN and PMN-mediated HMVEC cytotoxicity. Furthermore, incubation of PMNs in clinically relevant HTS (180 mM NaCl) prevents PHSML PMN priming and PMN:HMVEC interactions. These studies suggest inhibition of PMN signal transduction is a mechanism whereby HTS resuscitation abrogates acute lung injury.

The effect of tonicity and hypertonic solutions on microvascular permeability

BACKGROUND

The effect of hypertonic saline (HS) on microvascular permeability is unclear. We hypothesized that varying degrees of tonicity and HS solutions alter microvascular fluid flux across the endothelium.

METHODS

Hydraulic permeability (L(p)) is a measure of water flow across the endothelial barrier. L(p) was measured in cannulated rat mesenteric venules using the modified Landis micro-occlusion technique. The effect of tonicity was tested by measuring L(p) after successive perfusions with Ringers' solutions of varying sodium chloride (NaCl) concentrations (85, 135, 185, and 235 mM) (n = 6). Additional venules were perfused with control Ringers' ([NaCl] = 135 mM) and measures of L(p) were obtained after subsequent perfusions with 7% NaCl followed by 7% NaCl with 6% dextran (n = 6).

RESULTS

Tonicity had a significant dose-dependent effect on L(p) (P < 0.0001). Perfusion with 7% NaCl significantly increased L(p) (P < 0.0001). The addition of 6% dextran to 7% NaCl significantly decreased L(p) compared with perfusion with 7% NaCl alone (P = 0.002).

CONCLUSIONS

We conclude that (1) tonicity influences microvascular permeability, (2) HS increases microvascular permeability, and (3) the addition of dextran to HS greatly attenuates this response. These findings suggest an important role for tonicity and a possible deleterious effect of HS in modulating microvascular permeability as well as the benefit of dextran with HS for maintaining intravascular volume.

Cytokine expression profiling in human leukocytes after exposure to hypertonic and isotonic fluids

BACKGROUND

Resuscitation from hemorrhagic shock causes profound immunologic changes. The tonicity of fluids used for resuscitation clearly influences the immune response. Our study was designed to determine whether isotonic and hypertonic fluids exert their differential effects on immune response by altering the cytokine gene profile of human leukocytes. The cDNA array method was used to profile transcriptional responses after exposure to hypertonic and isotonic fluids.

METHODS

Blood from seven healthy volunteers was incubated for 30 minutes with isotonic (10% dextran-40 and lactated Ringer's [LR] solution) and hypertonic (7.5% hypertonic saline and hypertonic dextran [HTD]) fluids. The volumes of isotonic fluids used were equal to the volume of blood, whereas the volumes of hypertonic fluids were adjusted to keep the salt load identical to the LR group. The cDNA array technique was used to measure the gene expression of 23 common cytokines.

RESULTS

Increased gene transcription of proinflammatory cytokines (interleukin [IL]-1alpha, IL-6, IL-10, and tumor necrosis factor-alpha) as well as others (IL-5, IL-7, and IL-16) was found after incubation with resuscitation fluids. Variances were noted depending on the type of fluid: HTD and LR solution did not induce expression of IL-5, and HTD also did not induce IL-1beta expression. Genes encoding IL-1alpha, IL-6, IL-9, and tumor necrosis factor-alpha had low level baseline expression in leukocytes isolated from unstimulated blood, and their expression increased markedly after exposure to resuscitation fluids. The inducible transcripts included IL-1beta, IL-7, IL-10, and IL-16. However, there was no difference in cytokine expression profile between isotonic and hypertonic fluids.

CONCLUSION

Exposure of human leukocytes to resuscitation fluids causes an increase in cytokine gene expressions compared with undiluted blood. This expression profile is largely independent of the type of fluid used.

Hypertonic preconditioning inhibits macrophage responsiveness to endotoxin

Hypertonic saline has been shown to modulate cell shape and the response of components of the innate immune response. However, the effect of hypertonic saline on the macrophage remains unknown. We hypothesized that hypertonic preconditioning would impair subsequent inflammatory mediator signaling through a reduction in stress fiber polymerization and mitogen-activated protein kinase activity after LPS stimulation. Rabbit alveolar macrophages were stimulated with 100 ng/ml of LPS. Selected cells were preconditioned with 40-100 mM of NaCl, mannitol, or urea for 4 h and returned to isotonic medium before LPS stimulation. Cellular protein was harvested and subjected to Western blot analysis for the dually phosphorylated active forms of p38 and extracellular signal-related kinase (ERK) 1/2. TNF production was determined by an L929 bioassay, and stress fiber polymerization was evaluated by confocal microscopy. Preconditioning of macrophages with NaCl or mannitol resulted in dose-dependent reduction in ERK 1/2 phosphorylation with no effect on p38 phosphorylation. Urea preconditioning had no effect on either mitogen-activated protein kinase. A dose-dependent attenuation of TNF production was seen with NaCl and mannitol preconditioning (p < 0.05), but not with urea. NaCl and mannitol preconditioning resulted in failure of LPS-induced stress fiber polymerization, whereas urea did not. Extracellular hypertonic conditions (i.e., NaCl and mannitol) have an immunomodulatory effect on macrophages, demonstrated through failure of optimal stress fiber polymerization, ERK 1/2 activity, and TNF production. Intracellular hypertonic conditions (i.e., urea) had no significant effect. Hypertonic saline or mannitol resuscitation, therefore, may help protect against multiple-organ dysfunction syndrome as a result of this reduced proinflammatory responsiveness.