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

Saline nasal irrigation and gargling in COVID-19: a multidisciplinary review of effects on viral load, mucosal dynamics, and patient outcomes

With unrelenting SARS-CoV-2 variants, additional COVID-19 mitigation strategies are needed. Oral and nasal saline irrigation (SI) is a traditional approach for respiratory infections/diseases. As a multidisciplinary network with expertise/experience with saline, we conducted a narrative review to examine mechanisms of action and clinical outcomes associated with nasal SI, gargling, spray, or nebulization in COVID-19. SI was found to reduce SARS-CoV-2 nasopharyngeal loads and hasten viral clearance. Other mechanisms may involve inhibition of viral replication, bioaerosol reduction, improved mucociliary clearance, modulation of ENaC, and neutrophil responses. Prophylaxis was documented adjunctive to personal protective equipment. COVID-19 patients experienced significant symptom relief, while overall data suggest lower hospitalization risk. We found no harm and hence recommend SI use, as safe, inexpensive, and easy-to-use hygiene measure, complementary to hand washing or mask-wearing. In view of mainly small studies, large well-controlled or surveillance studies can help to further validate the outcomes and to implement its use.

Admission serum sodium and osmolarity are not associated with the occurrence or outcomes of acute respiratory distress syndrome in critically ill

BACKGROUND

Previous studies suggested that hypernatremia or hyperosmolarity may have protective effects in lung injury. We hypothesized that hypernatremia and/or hyperosmolarity would prevent ARDS.

DESIGN

Retrospective cohort study of all admissions at medical, surgical, and multidisciplinary intensive care units in Mayo Clinic, Rochester from the year of 2009 to 2019. The occurrence of ARDS was identified using a validated computerized search strategy. The association between serum sodium/osmolarity and the occurrence of ARDS was analyzed using a multivariable logistic regression model. The relationship between serum sodium/osmolarity and outcomes of ARDS was analyzed using linear and logistic regression models.

RESULTS

Among 50,498 patients, the serum sodium level on admission did not have a significant association with the occurrence of ARDS, with an adjusted odds ratio of 0.95 [95% CI (0.86, 1.05)]. There was no significant association between calculated serum osmolarity and the occurrence of ARDS, with an adjusted odds ratio of 1.03 [95% CI (1.00, 1.07)]. 1560 patients developed ARDS during the ICU stay. Their serum sodium level and osmolarity level did not have a significant association with their outcomes.

CONCLUSIONS

Admission serum sodium or serum osmolarity were not associated with the occurrence or outcomes of ARDS in ICU.

Hypertonic Solution in Severe COVID-19 Patient: A Potential Adjuvant Therapy

Coronavirus disease 2019 (COVID-19) features hyper-inflammation, cytokine storm, neutrophil function changes, and sodium chloride (NaCl) homeostasis disruption, while the treatment with NaCl hypertonic solutions (HS) controls electrolytic body homeostasis and cell functions. HS treatment is a simple, popular, economic, and feasible therapy to regulate leukocyte function with a robust anti-inflammatory effect in many inflammatory diseases. The purpose of this narrative review is to highlight the knowledge on the use of HS approaches against viral infection over the past years and to describe the mechanisms involved in the release of neutrophil extracellular traps (NETs) and production of cytokine in severe lung diseases, such as COVID-19. We reported the consequences of hyponatremia in COVID-19 patients, and the immunomodulatory effects of HS, either in vitro or in vivo. We also described the relationship between electrolyte disturbances and COVID-19 infection. Although there is still a lack of clinical trials, hypertonic NaCl solutions have marked effects on neutrophil function and NETs formation, emerging as a promising adjuvant therapy in COVID-19.

High Salt Induces a Delayed Activation of Human Neutrophils

High salt (NaCl) concentrations are found in a number of tissues under physiological and pathological conditions. Here, we analyzed the effects induced by high salt on the function of human neutrophils. The culture of neutrophils in medium supplemented with high salt (50 mM NaCl) for short periods (30-120 min) inhibited the ability of conventional agonists to induce the production of IL-8 and the activation of respiratory burst. By contrast, exposure to high salt for longer periods (6-18 h) resulted in the activation of neutrophils revealed by the production of high levels of IL-8, the activation of the respiratory burst, and a marked synergistic effect on the production of TNF-α induced by LPS. Increasing osmolarity of the culture medium by the addition of sorbitol or mannitol (100 mM) was shown to be completely unable to stimulate neutrophil responses, suggesting that high sodium but not an increased osmolarity mediates the activation on neutrophils responses. A similar biphasic effect was observed when the function of monocytes was analyzed. Short term exposure to high salt suppressed IL-8 and TNF-α production induced by LPS while culture for longer periods triggered the production of IL-8 but not TNF-α in the absence of LPS stimulation. Contradictory results have been published regarding how high salt modulates neutrophil function. Our results suggest that the modulation of neutrophil function by high salt is strongly dependent on the exposure time.

Physiological and Pathophysiological Roles of Metabolic Pathways for NET Formation and Other Neutrophil Functions

Neutrophils are the most numerous cells in the leukocyte population and essential for innate immunity. To limit their effector functions, neutrophils are able to modulate glycolysis and other cellular metabolic pathways. These metabolic pathways are essential not only for energy usage, but also for specialized effector actions, such as the production of reactive oxygen species (ROS), chemotaxis, phagocytosis, degranulation, and the formation of neutrophil extracellular traps (NETs). It has been demonstrated that activated viable neutrophils can produce NETs, which consists of a DNA scaffold able to bind granule proteins and microorganisms. The formation of NETs requires the availability of increased amounts of adenosine triphosphate (ATP) as it is an active cellular and therefore energy-dependent process. In this article, we discuss the glycolytic and other metabolic routes in association with neutrophil functions focusing on their role for building up NETs in the extracellular space. A better understanding of the requirements of metabolic pathways for neutrophil functions may lead to the discovery of molecular targets suitable to develop novel anti-infectious and/or anti-inflammatory drugs.

Effects of Hypertonic Saline and Hydroxyethyl Starch on Myeloid-Derived Suppressor Cells in Hemorrhagic Shock Mice under Secondary Bacterial Attack

Objectives

The primary target is to reveal whether the resuscitation with hypertonic saline (HTS) or hydroxyethyl starch (HES) would have different effects on the myeloid-derived suppressor cell (MDSC) count and monocytic MDSC (M-MDSC)/granulocytic/neutrophilic MDSC (G-MDSC) rate in the peripheral blood, spleen, and bone marrow nucleated cells (BMNC) in a controlled hemorrhagic shock mouse model under secondary Escherichia coli bacterial infection attack, comparing to resuscitation with normal saline (NS) in 72 hours.

Method

After hemorrhagic shock with bacteremia, which is induced by Escherichia coli bacterial infection attack, comparing to resuscitation with normal saline (NS) in 72 hours. Method. After hemorrhagic shock with bacteremia, which is induced by Escherichia coli 35218 injection, the mice were distributed into control, NS, HTS, and HES groups. The peripheral blood nucleated cells (PBNC), spleen single-cell suspension, and bone marrow nucleated cells were collected. The flow cytometry was used to detect the MDSC, M-MDSC, and G-MDSC.

Result

In PBNC, after resuscitation with NS, the MDSC was continuously higher, while the rate of M-MDSC/G-MDSC were continuously lower (P < 0.05). In HTS, the MDSC varied, higher at 24 and 72 hours (P < 0.05). In HTS, the MDSC varied, higher at 24 and 72 hours (P < 0.05). In HTS, the MDSC varied, higher at 24 and 72 hours (P < 0.05). In HTS, the MDSC varied, higher at 24 and 72 hours (P < 0.05). In HTS, the MDSC varied, higher at 24 and 72 hours (P < 0.05), the M-MDSC/G-MDSC were continuously lower (P < 0.05). In the spleen, resuscitation with HTS, the M-MDSC/G-MDSC were continuously lower (P < 0.05). In BMNC, after resuscitation with HES, the M-MDSC/G-MDSC were lower at 24 and 72 hours (P < 0.05).

Conclusion

In mouse hemorrhagic shock model with bacterial infection, the resuscitation with NS, HTS, or HES induced difference changes in MDSC and M-MDSC/G-MDSC, which were time-dependent and organ-specific. Resuscitation with crystalloid, like NS or HTS, showed longer effects on the MDSC and M-MDSC/G-MDSC in peripheral blood; while HTS has a longer effect on M-MDSC/G-MDSC in the spleen, HES has a stronger impact on the differentiation regulation of MDSC to G-MDSC in the bone marrow.

TNF-α promotes nuclear enrichment of the transcription factor TonEBP/NFAT5 to selectively control inflammatory but not osmoregulatory responses in nucleus pulposus cells

Intervertebral disc degeneration (IDD) causes chronic back pain and is linked to production of proinflammatory molecules by nucleus pulposus (NP) and other disc cells. Activation of tonicity-responsive enhancer-binding protein (TonEBP)/NFAT5 by non-osmotic stimuli, including proinflammatory molecules, occurs in cells involved in immune response. However, whether inflammatory stimuli activate TonEBP in NP cells and whether TonEBP controls inflammation during IDD is unknown. We show that TNF-α, but not IL-1β or LPS, promoted nuclear enrichment of TonEBP protein. However, TNF-α-mediated activation of TonEBP did not cause induction of osmoregulatory genes. RNA sequencing showed that 8.5% of TNF-α transcriptional responses were TonEBP-dependent and identified genes regulated by both TNF-α and TonEBP. These genes were over-enriched in pathways and diseases related to inflammatory response and inhibition of matrix metalloproteases. Based on RNA-sequencing results, we further investigated regulation of novel TonEBP targets CXCL1, CXCL2, and CXCL3 TonEBP acted synergistically with TNF-α and LPS to induce CXCL1-proximal promoter activity. Interestingly, this regulation required a highly conserved NF-κB-binding site but not a predicted TonE, suggesting cross-talk between these two members of the Rel family. Finally, analysis of human NP tissue showed that TonEBP expression correlated with canonical osmoregulatory targets TauT/SLC6A6, SMIT/SLC5A3, and AR/AKR1B1, supporting in vitro findings that the inflammatory milieu during IDD does not interfere with TonEBP osmoregulation. In summary, whereas TonEBP participates in the proinflammatory response to TNF-α, therapeutic strategies targeting this transcription factor for treatment of disc disease must spare osmoprotective, prosurvival, and matrix homeostatic activities.

Immunomodulatory effect of hypertonic saline in hemorrhagic shock

Multiple organ dysfunction syndrome (MODS) and nosocomial infection following trauma-hemorrhage are among the most important causes of mortality in hemorrhagic shock patients. Dysregulation of the immune system plays a central role in MODS and a fluid having an immunomodulatory effect could be advantageous in hemorrhagic shock resuscitation. Hypertonic saline (HS) is widely used as a resuscitation fluid in trauma-hemorrhagic patients. Besides having beneficial effects on the hemodynamic parameters, HS has modulatory effects on various functions of immune cells such as degranulation, adhesion molecules and cytokines expression, as well as reactive oxygen species production. This article reviews clinical evidence for decreased organ failure and mortality in hemorrhagic shock patients resuscitated with HS. Despite promising results in animal models, results from pre-hospital and emergency department administration in human studies did not show improvement in survival, organ failure, or a reduction in nosocomial infection by HS resuscitation. Further post hoc analysis showed some benefit from HS resuscitation for severely-injured patients, those who received more than ten units of blood by transfusion, patients who underwent surgery, and victims of traumatic brain injury. Several reasons are suggested to explain the differences between clinical and animal models.

The effect of hypertonic saline on mRNA of proinflammatory cytokines in lipopolysaccharide-stimulated polymorphonuclear cells

Background

Hypertonic saline is often used to resuscitate patients experiencing shock. In such conditions, polymorphonuclear cells and Toll-like receptors (TLRs) form an essential part of early induced innate immunity.

Objective

To investigate the immunomodulatory effect of hypertonic saline on polymorphonuclear cells by evaluating the changes in TLR-4 receptors and proinflammatory cytokines.

Methods

Polymorphonuclear cells were isolated from whole blood using Polymorphprep (Axis-Shield, Oslo, Norway). The isolated polymorphonuclear cells were plated at a density of 1 × 10⁶ cells/mL in 6-well flat-bottomed culture plates and were stimulated with 1 μg/mL lipopolysaccharide or N-formyl-methionyl-leucyl-phenylalanine. The stimulated polymorphonuclear cells were cultured in hypertonic saline at 10, 20, or 40 mmol/L above isotonicity. After that, the changes in TLR-4 and cytokines were measured by quantitative real-time polymerase chain reaction and flow cytometry.

Results

The level of TLR-4 mRNA expression decreased after stimulation with N-formyl-methionyl-leucyl-phenylalanine, but hypertonic saline did not affect the TLR-4 mRNA expression. TLR-4 mRNA expression was clearly induced upon stimulation with lipopolysaccharide, and the addition of hypertonic saline restored TLR-4 mRNA expression in polymorphonuclear cells. The interleukin-1β mRNA expression was decreased in the hypertonic environment. On the other hand, the tumor necrosis factor-α value was not influenced by the addition of hypertonic saline.

Conclusions

Hypertonic saline has an immunomodulatory effect on polymorphonuclear cells through the TLR-4 pathway, and the interleukin–1β-associated pathway is influenced more by hypertonic saline than is the tumor necrosis factor–α-associated pathway.

Effect of Hypotensive Resuscitation with a Novel Combination of Fluids in a Rabbit Model of Uncontrolled Hemorrhagic Shock

Objective

The aim of this study was to compare the effects of hypotensive and normotensive resuscitation with a novel combination of fluids via lactate Ringer’s solution (LRS), 6% hydroxyethyl starch 130/0.4 solution (HES), and 7.5% hypertonic saline solution (HSS) at early stage of uncontrolled hemorrhagic shock (UHS) before hemostasis.

Methods

New Zealand white rabbits (n = 32) underwent UHS by transecting the splenic parenchyma, followed by blood withdrawal via the femoral artery to target mean arterial pressure (MAP) of 40–45 mmHg. Animals were distributed randomly into 4 groups (n = 8): in group Sham, sham operation was performed; in group HS, UHS was untreated; in group HS-HR, UHS was treated by hypotensive resuscitation with HSS and LRS+HES (ratio of 2∶1) to MAP of 50–55 mmHg; in group HS-NR, UHS was treated by normotensive resuscitation with HSS and LRS+HES (ratio of 2∶1) to MAP of 75–80 mmHg. Outcomes of hemodynamics, inflammatory and oxidative response, and other metabolic variables were measured and the histopathological studies of heart, lung and kidney were performed at the end of resusucitation.

Results

Hypotensive resuscitation with the novel combination of fluids for UHS rabbits decreased blood loss, maintained better stabilization of hemodynamics, and resulted in relatively higher hematocrit and platelet count, superior outcomes of blood gas, and lower plasma lactate concentration. Besides, hypotensive resuscitation attenuated the inflammatory and oxidative response significantly in UHS rabbits.

Conclusion

Hypotensive resuscitation with the novel combination of fluids via HSS and LRS+HES (ratio of 2∶1) has an effective treatment at early stage of UHS before hemostasis.

Nebulized hypertonic saline attenuates acute lung injury following trauma and hemorrhagic shock via inhibition of matrix metalloproteinase-13

OBJECTIVE

We hypothesized that aerosolized inhaled hypertonic saline given at the onset of resuscitation will decrease acute lung injury following hemorrhagic shock, by inhibiting the release of epithelial derived proinflammatory mediators.

DESIGN

Animal study.

SETTING

Animal-care facility procedure room in a medical center.

SUBJECTS

Adult male Sprague-Dawley rats.

INTERVENTIONS

Rats underwent hemorrhagic shock followed by 2 hrs of resuscitation and 1 hr of observation. In the study group, nebulized hypertonic saline was delivered at the end of the shock period and after 1 hr and 2 hrs of resuscitation.

MEASUREMENTS AND MAIN RESULTS

Shock provoked acute lung injury, which was attenuated with inhaled hypertonic saline (1.56 ± 0.2 mg protein/mL vs. 0.95 ± 0.3 mg protein/mL bronchoalveolar lavage fluid, shock vs. shock + hypertonic saline, p < .01). Nebulized hypertonic saline reduced inflammation (cytokine-induced neutrophil chemoattractant-1 accumulation in bronchoalveolar lavage fluid 5999 ± 1267 pg/mL vs. 3342 ± 859 pg/mL, shock vs. shock + hypertonic saline, p = .006). Additionally, nebulized hypertonic saline inhibited matrix -metalloproteinase-13 accumulation in the bronchoalveolar lavage fluid (1513 ± 337 pg/mL bronchoalveolar lavage fluid vs. 230 ± 19 pg/mL, shock vs. shock + hypertonic saline, p = .009) and pretreatment with a matrix metalloproteinase-13 inhibitor was sufficient to attenuate postshock acute lung injury (1.42 ± 0.09 mg/mL vs. 0.77 ± 0.23 mg/mL bronchoalveolar lavage protein, shock vs. shock + matrix metalloproteinase-13 inhibitor CL-82198, p = .002).

CONCLUSION

Inhaled hypertonic saline attenuates postshock acute lung injury by exerting an anti-inflammatory effect on the pulmonary epithelium, suggesting a new clinical strategy to treat acute lung injury/acute respiratory distress syndrome.

Persistence of inflammatory response to intense exercise in diabetic rats

In this study we evaluated the onset and resolution of inflammation in control and streptozotocin-induced diabetic rats subjected to a single session of intense exercise. The following measurements were carried out prior to, immediately after, and 2 and 24 hours after exercise: plasma levels of proinflammatory cytokines (TNF-α, IL-1β, IL-6, CINC-2α/β, MIP-3α, and IL-6), immunoglobulins (IgA and IgM), acute phase proteins (CRP and C3), and creatine kinase (CK) activity. We also examined the occurrence of macrophage death by measurements of macrophages necrosis (loss of membrane integrity) and DNA fragmentation. An increase was observed in the concentration of IL-1β (3.3-fold) and TNF-α (2.0-fold) and in the proportion of necrotic macrophages (4.5-fold) in diabetic rats 24 hours after exercise, while the control group showed basal measurements. Twenty-four hours after the exercise, serum CK activity was elevated in diabetic rats but not in control animals. We concluded that lesion and inflammations resulting from intense exercise were greater and lasted longer in diabetic animals than in nondiabetic control rats.

Effects of hypertonic saline on macrophage migration inhibitory factor in traumatic conditions

Trauma-induced suppression of cellular immune function contributes to sepsis, multiple organ dysfunction syndrome (MODS) and mortality. Macrophage migration inhibitory factor (MIF) has been revealed to be central to several immune responses. However, the role of MIF in trauma-like conditions is unknown. Therefore, the present study evaluated MIF in macrophages and polymorphonuclear neutrophils (PMNs). The effects of hypertonic saline (HTS) on lipopolysaccharide (LPS)-induced MIF levels were evaluated in macrophages. MIF concentrations were determined by an enzyme-linked immnosorbent assay (ELISA) and cell lysates were used for western blot analysis. The effects of HTS on N-formyl-methionyl-leucyl-phenylalanine (fMLP)-induced MIF were evaluated in PMNs. MIF concentrations were determined by ELISA, western blotting and real time-polymerase chain reaction (RT-PCR) to determine MIF expression. MIF levels, which were measured by the ELISA, increased by 1.24±0.38 ng/ml in the supernatants of LPS-stimulated macrophages compared with the controls (0.79±0.07 ng/ml) at 2 h. HTS10 (150 mmol/l) partially restored MIF levels (0.84±0.22 ng/ml; P<0.05). Also, western blotting was performed and MIF protein levels were higher in the LPS-stimulated macrphages (20% increase in band density) compared with the controls (P<0.05). The addition of HTS decreased MIF protein expression. MIF levels in fMLP-stimulated PMN cells were unchanged compared with the controls according to the ELISA, western blotting and RT-PCR. No effects were observed following treatment with HTS. MIF concentrations and MIF expression were higher in LPS-stimulated macrophages than controls and HTS restored MIF levels to those of the controls. MIF levels were unchanged in PMNs stimulated by fMLP.

Effect of hypertonic saline on apoptosis of polymorphonuclear cells

BACKGROUND

The function of polymorphonuclear (PMN) cells can be influenced by the choice of resuscitation fluids in hemorrhagic shock. Widespread interest in the use of hypertonic solutions for resuscitation has led to extensive investigation of their immune-modulating properties. Hypertonic saline (HTS) is known to modulate immune reactions, preventing the multiorgan failure mediated by immune reactions in trauma and hemorrhagic shock. PMN cells play a key role in such immune-mediated inflammatory processes, and HTS is believed to affect these PMN cells. However, how these events influence the actual event of apoptosis has not yet been described. Thus, in the present study, we aimed to investigate the differences in the apoptosis of PMN cells when exposed to isotonic and hypertonic environments and the temporal relations between the interval of administration of HTS after the stimulation of PMN cells.

METHODS

Whole blood was sampled from healthy volunteers, and the PMN cells were isolated. The isolated layer of PMN cells was washed twice with phosphate-buffered saline to yield the PMN cells. The number of cells was kept uniform, and an overall survival rate greater than 95% was maintained. After stimulation of the isolated PMN cells with N-formyl-methionyl-leucyl-phenylalanine, the PMN cells were allocated into 3 study groups (i.e., 1 isotonic group and 2 hypertonic groups with an osmolarity of 160 mM and 180 mM each). The extent of apoptosis was investigated in each group after culturing the PMN cells for 0, 1, 3, 6, 12, 15, 18, and 24 h. Depending on whether the PMN cells were stimulated with N-formyl-methionyl-leucyl-phenylalanine, they were also divided into stimulated and nonstimulated groups. In the stimulated group, the hypertonic environment was fostered immediately (HTS 0 h) and 6 h (HTS 6 h) after stimulation, which was accomplished after allocating the cells into an isotonic group (140 mM) and a hypertonic group (180 mM), according to the concentration of the culture medium. The PMN cells were then cultured at 37°C for 15 h with 5% carbon dioxide incubation. Each PMN suspension was labeled with Annexin V-fluorescein isothiocyanate and propidium iodide. Each sample underwent immediate flow cytometric analysis. PMN cells with high propidium iodide uptake were considered nonviable (necrotic). Among the viable PMN cells, those with no Annexin V uptake were considered normal and those with Annexin V uptake were considered apoptotic.

RESULTS

Decreased apoptosis was observed in the PMN cells stimulated with N-formyl-methionyl-leucyl-phenylalanine. Increased apoptosis was observed in the stimulated PMN cells incubated in hypertonic condition compared with the cells incubated in isotonic condition. Early HTS administration demonstrated increased apoptosis compared with late administration.

CONCLUSIONS

HTS treatment resulted in increased PMN apoptosis and an anti-inflammatory effect. Decreased apoptosis (prolonged lifespan) has been implicated in neutrophil-mediated tissue damage. HTS, by increasing the apoptosis of PMN cells, attenuates the postinjury inflammatory response. Also, early treatment with HTS was more efficient than delayed treatment.

Hypertonicity-enhanced TNF-α release from activated human monocytic THP-1 cells requires ERK activation

BACKGROUND

Hypertonic stress enhances tumor necrosis factor (TNF)-α expression in activated monocytes. However, the underlying mechanism is unknown. The produced TNF-α is primarily cleaved and released by TNF-α-converting enzyme (TACE), and the surface expression of TACE is down-regulated by endocytosis. As hypertonicity inhibits endocytosis, we evaluated the mechanism of hypertonicity-induced TNF-α release from activated human monocytic THP-1 cells.

METHODS

THP-1 cells were stimulated with lipopolysaccharide (LPS) or phorbol 12-myristate 13-acetate (PMA) in the presence or absence of hypertonic agents (150 mM sucrose or 150-300 mM NaCl). The amount of TNF-α mRNA and protein, surface expression of TACE and activation of signaling pathways (mitogen-activated protein kinase, Akt and NF-κB) were assayed.

RESULTS

Hypertonic sucrose and NaCl significantly enhanced TNF-α release from THP-1 cells upon LPS or PMA stimulation. Hypertonic sucrose and other endocytosis inhibitors increased surface expression of TACE, but their effects on TNF-α release were inconsistent. This enhancement effect by hypertonicity was not attenuated by inhibition of TACE or IκB kinase, but it was blocked by cycloheximide and a MAP/ERK kinase inhibitor. The LPS- or PMA-induced TNF-α mRNA expression was not increased; rather, it was inhibited by hypertonicity. ERK1/2 was re-activated after sucrose treatment in LPS-stimulated THP-1 cells.

CONCLUSIONS

Hypertonicity-enhanced TNF-α protein synthesis from LPS- or PMA-activated THP-1 cells requires ERK activation and may proceed without TACE.

GENERAL SIGNIFICANCE

A vast amount of TNF-α production was regulated by a crucial post-transcriptional manner in activated human monocytic leukemia cells, and it may possibly be contributed to the cachexia condition.

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.

Prehospital resuscitation with hypertonic saline-dextran modulates inflammatory, coagulation and endothelial activation marker profiles in severe traumatic brain injured patients

Background

Traumatic brain injury (TBI) initiates interrelated inflammatory and coagulation cascades characterized by wide-spread cellular activation, induction of leukocyte and endothelial cell adhesion molecules and release of soluble pro/antiinflammatory cytokines and thrombotic mediators. Resuscitative care is focused on optimizing cerebral perfusion and reducing secondary injury processes. Hypertonic saline is an effective osmotherapeutic agent for the treatment of intracranial hypertension and has immunomodulatory properties that may confer neuroprotection. This study examined the impact of hypertonic fluids on inflammatory/coagulation cascades in isolated head injury.

Methods

Using a prospective, randomized controlled trial we investigated the impact of prehospital resuscitation of severe TBI (GCS < 8) patients using 7.5% hypertonic saline in combination with 6% dextran-70 (HSD) vs 0.9% normal saline (NS), on selected cellular and soluble inflammatory/coagulation markers. Serial blood samples were drawn from 65 patients (30 HSD, 35 NS) at the time of hospital admission and at 12, 24, and 48-h post-resuscitation. Flow cytometry was used to analyze leukocyte cell-surface adhesion (CD62L, CD11b) and degranulation (CD63, CD66b) molecules. Circulating concentrations of soluble (s)L- and sE-selectins (sL-, sE-selectins), vascular and intercellular adhesion molecules (sVCAM-1, sICAM-1), pro/antiinflammatory cytokines [tumor necrosis factor (TNF)-α and interleukin (IL-10)], tissue factor (sTF), thrombomodulin (sTM) and D-dimers (D-D) were assessed by enzyme immunoassay. Twenty-five healthy subjects were studied as a control group.

Results

TBI provoked marked alterations in a majority of the inflammatory/coagulation markers assessed in all patients. Relative to control, NS patients showed up to a 2-fold higher surface expression of CD62L, CD11b and CD66b on polymorphonuclear neutrophils (PMNs) and monocytes that persisted for 48-h. HSD blunted the expression of these cell-surface activation/adhesion molecules at all time-points to levels approaching control values. Admission concentrations of endothelial-derived sVCAM-1 and sE-selectin were generally reduced in HSD patients. Circulating sL-selectin levels were significantly elevated at 12 and 48, but not 24 h post-resuscitation with HSD. TNF-α and IL-10 levels were elevated above control throughout the study period in all patients, but were reduced in HSD patients. Plasma sTF and D-D levels were also significantly lower in HSD patients, whereas sTM levels remained at control levels.

Conclusions

These findings support an important modulatory role of HSD resuscitation in attenuating the upregulation of leukocyte/endothelial cell proinflammatory/prothrombotic mediators, which may help ameliorate secondary brain injury after TBI.

Trial registration

NCT00878631.

Peripheral osmotic stimulation inhibits the brain's innate immune response to microdialysis of acidic perfusion fluid adjacent to supraoptic nucleus

During the brain's innate immune response microglia, astroglia and ependymal cells resolve/repair damaged tissue and control infection. Released interleukin-1beta (IL-1beta) reaching cerebroventricles stimulates circumventricular organs (CVOs; subfornical organ, SFO; organum vasculosum lamina terminalis, OVLT), the median preoptic nucleus (MePO), and magnocellular and parvocellular neurons in the supraoptic (SON) and paraventricular (PVN) nuclei. Hypertonic saline (HS) also activates these osmosensory CVOs and neuroendocrine systems, but, in contrast to IL-1beta, inhibits the peripheral immune response. To examine whether the brain's innate immune response is attenuated by osmotic stimulation, sterile acidic perfusion fluid was microdialyzed (2 microl/min) in the SON area of conscious rats for 6 h with sterile HS (1.5 M NaCl) injected subcutaneously (15 ml/kg) at 5 h. Immunohistochemistry identified cytokine sources (IL-1beta(+); OX-42(+) microglia) and targets (IL-1R(+); inducible cyclooxygenase, COX-2(+); c-Fos(+)) near the probe, in CVOs, MePO, ependymal cells, periventricular hypothalamus, SON, and PVN. Inserting the probe stimulated magnocellular neurons (c-Fos(+); SON; PVN) via the MePO (c-Fos(+)), a response enhanced by HS. Microdialysis activated microglia (OX-42(+); amoeboid/hypertrophied; IL-1beta(+)) in the adjacent SON and bilaterally in perivascular areas of the PVN, periventricular hypothalamus and ependyma, coincident with c-Fos expression in ependymal cells and COX-2 in the vasculature. These microglial responses were attenuated by HS, coincident with activating parvocellular and magnocellular neuroendocrine systems and elevating circulating IL-1beta, oxytocin, and vasopressin. Acidosis-induced cellular injury from microdialysis activated the brain's innate immune response by a mechanism inhibited by peripheral osmotic stimulation.

Hyperosmotic stress enhances cytokine production and decreases phagocytosis in vitro

Introduction

Hyperglycemia is associated with negative outcomes in various settings of critical illness; infectious complications, especially, seem to be increased. On the other hand, intensive insulin therapy (IIT) has been shown to improve outcome in clinical trials. Whether normoglycemia itself or the application of insulin is responsible for the observed findings is unknown. We therefore tested the effect of glucose and insulin on various immune functions in vitro.

Methods

Human peripheral blood mononuclear cells (PBMCs) were incubated ex vivo with low doses of lipopolysaccharide (LPS). PBMCs were incubated with various osmotic agents, insulin, or a combination of both. Interleukin (IL)-6 and IL-1 cytokine response was measured by enzyme-linked immunosorbent assay. In addition, we investigated the effects of glucose on phagocytosis and oxidative burst in human granulocytes.

Results

Increasing concentrations of both glucose and mannitol significantly enhanced LPS-induced cytokine production. Insulin alone did not alter cytokine production and had only a minor influence in combination with glucose. Phagocytosis and oxidative burst were significantly reduced with increasing concentrations of glucose and mannitol.

Conclusion

Hyperglycemia may lead to inflammation by enhancing cytokine production via the direct effects of hyperosmotic stress. Impaired phagocytosis and oxidative burst under hyperglycemia may weaken defense mechanisms of the host. Our in vitro findings may help to explain the beneficial effects of IIT not only in diabetic but also in critically ill patients.