Selective inhibition of polymorphonuclear neutrophils by resuscitative concentration of hypertonic saline

Inhaled hypertonic saline for cystic fibrosis: Reviewing the potential evidence for modulation of neutrophil signalling and function

Cystic fibrosis (CF) is a multisystem disorder with significantly shortened life expectancy. The major cause of mortality and morbidity is lung disease with increasing pulmonary exacerbations and decline in lung function predicting significantly poorer outcomes. The pathogenesis of lung disease in CF is characterised in part by decreased airway surface liquid volume and subsequent failure of normal mucociliary clearance. This leads to accumulation of viscous mucus in the CF airway, providing an ideal environment for bacterial pathogens to grow and colonise, propagating airway inflammation in CF. The use of nebulised hypertonic saline (HTS) treatments has been shown to improve mucus clearance in CF and impact positively upon exacerbations, quality of life, and lung function. Several mechanisms of HTS likely improve outcome, resulting in clinically relevant enhancement in disease parameters related to increase in mucociliary clearance. There is increasing evidence to suggest that HTS is also beneficial through its anti-inflammatory properties and its ability to reduce bacterial activity and biofilm formation. This review will first describe the use of HTS in treatment of CF focusing on its efficacy and tolerability. The emphasis will then change to the potential benefits of aerosolized HTS for the attenuation of receptor mediated neutrophil functions, including down-regulation of oxidative burst activity, adhesion molecule expression, and the suppression of neutrophil degranulation of proteolytic enzymes.

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.

Hypertonic saline downregulate the production level of lipopolysaccharide-induced migration inhibitory factor in THP-1 cells

Purpose

Macrophage migration inhibitory factor (MIF) may serve as a general marker for systemic inflammation in septic and nonseptic acute critical illness. Additionally, our previous experiment has demonstrated that immunosuppressant Prostaglandin E₂ (PGE₂) lowered MIF levels and inhibited T-cells proliferation when compared to control levels. The addition of hypertonic saline (HTS) increased MIF production as compared with PGE₂-stimulated T-cells in concordance with restore PGE₂-suppressed T-cells proliferation. Generally, HTS has been well known for its anti-inflammatory effect so far. Therefore, the experiments were conducted to evaluate MIF after stimulating lipopolysaccharide (LPS) either in the presence or absence of HTS in monocyte, in response to early phase injury.

Methods

Human acute monocytic leukemic cell line (THP-1) cells were cultured in RPMI media, to a final concentration of 1 × 10⁶ cells/mL. The effect of HTS on LPS-induced MIF was evaluated in monocyte with 1 µg/mL LPS. HTS at 10, 20 or 40 mmol/L above isotonicity was added. MIF concentrations of the supernatant were determined by enzyme-linked immunosorbent assay, and cell lysates were used for Western blots analysis to determine the MIF expression.

Results

MIF concentrations in the cell supernatant increased in LPS-induced cells compared to control cells. Also, levels of MIF protein expression were higher in LPS stimulating cells. However, the addition of HTS to LPS stimulated cell restored MIF concentrations and MIF expression.

Conclusion

The role of HTS in maintaining physiological balance in human beings, at least in part, should be mediated through the MIF pathway.

Resuscitative effect of hyperoxia fluid on high-altitude hemorrhagic shock in rats and antishock mechanisms

Pathophysiological characteristics of hemorrhagic shock at high altitude are different from that at plain which involve severe injury, high mortality, difficult treatment and compromised liquid tolerance. High-altitude pulmonary/cerebral edema and multiple-organ dysfunction render the conventional treatment ineffective. Herein, we evaluated the resuscitation effects of hyperoxia solution on high-altitude hemorrhagic shock in rats. For this purpose, a rat model of high-altitude (3,658 m) hemorrhagic shock was established on the plateau and hyperoxia solution (4 ml/kg) was infused through external jugular vein for resuscitation at 60 min post-hemorrhage. Blood pressure, blood gas, left and right ventricular pressure, lung and brain water content, survival time, survival rate at 2 h, levels of inflammatory cytokines and free oxygen radicals in blood and tissue were determined. After resuscitation with hyperoxia solution, blood pressure, arterial oxygen partial pressure, left and right ventricular systolic pressure, ±dp/dt max, survival time and rate were significantly increased. Lung and brain water content were unchanged, malondialdehyde activity in lung, brain and plasma and levels of TNF-α, IL-1, IL-6, and endothelin were significantly decreased. Besides, CGRP was elevated with reduced injury and improved lung and kidney functions. Concludingly, resuscitation with hyperoxia solution is feasible and more effective than other classical liquids, making it the first choice of treatment for high-altitude hemorrhagic shock.

Impact of hypertonic saline on the release of selected cytokines after stimulation with LPS or peptidoglycan in ex vivo whole blood from healthy humans

The question of specific immunomodulating qualities of hypertonic saline (HTS) has not been settled. It has proven difficult to distinguish between immunomodulation directly attributable to HTS and influence because of favorable circulatory effects. The nature of immune activator may also play a role. In a whole-blood model, we have investigated these relations further, with special emphasize on osmolalities usually found after recommended dosing. Blood from 10 healthy donors was exposed to osmolalities ranging from 295 to 480 mOsm/kg and stimulated with the two clinically relevant stimulators peptidoglycan (1 µg/mL) or LPS (10 ng/mL) for 6 h at 37°C. Leukocyte response was evaluated by measuring selected cytokines in the supernatant. Moderate hyperosmolality alone boosted the release of CXCL8/IL-8. The peptidoglycan-stimulated synthesis of pivotal proinflammatory cytokines was inhibited in an osmolality-dependent way, but statistically significant only at osmolalities above those attained after routine use of HTS, i.e., 310 mOsm/kg or greater: IL-6 (P < 0.05 at 315 mOsm/kg), IL-1ß, and TNF-α (P < 0.05 at 335 mOsm/kg). Similar effects were seen for the chemokine CCL3 and the anti-inflammatory cytokine IL-10. In contrast, the effects in cells stimulated with LPS were either lower or absent. Thus, osmolalities usually found after clinical use of HTS only modestly influenced the selected immune parameters, regardless of stimulator.

Concentration of arginine and optimal time of hypertonic saline in restoration of T-cell dysfunction

BACKGROUND

Hypertonic saline (HS) restores prostaglandin E(2) (PGE(2))-induced T-cell suppression in the presence of 1100 microM arginine. However, under arginine-free culture conditions, HS dose not restore T-cell proliferation. Therefore, we wanted to determine if HS can restore PGE(2)-induced T-cell suppression in the presence of 80 microM of arginine, the physiologically relevant arginine concentration. We also wanted to determine the concentration of arginine that induces HS restoration of PGE(2)-suppressed T-cell proliferation and whether HS restoration of T-cell dysfunction is dependent on the injection time of HS.

MATERIALS AND METHODS

Jurkat cells were cultured in media containing 0, 40, 80, 400, 800, or 1100 microM arginine. In both the PGE(2)-stimulated and HS-treated group, we measured cell proliferation using MTT assay and arginase activity. We also measured cell proliferation relative to HS injection time.

RESULTS

In 80 microM arginine, HS did not restore Jurkat cell proliferation that had been suppressed by PGE(2). Increased concentrations of arginine in the media increased MTT cell proliferation. In 800 microM arginine media, HS restored PGE(2)-suppressed Jurkat cell proliferation to normal. HS restored PGE(2)-suppressed Jurkat cell proliferation when it was added at 2 h, similar to at same time and 1 h after PGE(2) stimulation.

CONCLUSIONS

In order to restore PGE(2)-suppressed Jurkat cell proliferation, HS requires at least 800 microM arginine. HS restored PGE(2)-suppressed Jurkat cell proliferation even though HS was added at 2 h after PGE(2) stimulation.

Role of the mTOR pathway in LPS-activated monocytes: influence of hypertonic saline

BACKGROUND

As heightened protein synthesis is the hallmark of many inflammatory syndromes, we hypothesize that the mammalian target of rapamycin (mTOR) pathway, which control the cap-dependent translation initiation phase, was activated by lipopolysaccharide (LPS). In addition, we studied the effect of hypertonic saline solution (HTS) on the mTOR cascade in peripheral blood mononuclear cells (PBMCs).

MATERIALS AND METHODS

PBMCs were isolated from healthy volunteers and treated with LPS. Cells were pretreated with phosphatidylinositol 3-kinase (PI3K) and mTOR inhibitors, or with HTS. Supernatants were harvested 20 h following LPS treatment, and interleukin-10 (IL-10), interleukin-6 (IL-6) and tumor necrosis alpha (TNFα) were analyzed by ELISA. Immunoblot experiments were performed for components of the PI3K/Akt/mTOR pathway at various time points. RNA was extracted after 90 min for real-time RT-PCR quantification.

RESULTS

The mTOR pathway is activated in PBMCs within 1 h of LPS stimulation. Pretreatment with rapamycin, a specific inhibitor of mTOR, resulted in a significant decrease of IL-10 and IL-6 translation and expression but did not affect the LPS-induced TNFα production. Both the mTOR pathway and the LPS-induced IL-6 production were down-regulated by HTS pretreatment.

CONCLUSIONS

The PI3k/Akt/mTOR cascade modulates LPS-induced cytokines production differentially. IL-10 and IL-6 expression are both up-regulated by activation of the mTOR pathway in response to LPS in PBMCs, while TNFα is not controlled by the mTOR cascade. Meanwhile, pretreatment of PBMCs with a HTS solution suppresses mTOR activity as well as LPS-induced IL-6, suggesting a more central role for mTOR as a regulator of the immuno-inflammatory response.

Activity of mannitol and hypertonic saline therapy on the oxidant and antioxidant system during the acute term after traumatic brain injury in the rats

In this study, our objective is to investigate the effects of mannitol and 7.5% hypertonic saline (HS) therapy on the levels of malondialdehyde (MDA), catalase and glutathione peroxidase (GSH-Px) in the early stages of experimental head traumas in rats. Rats included in the study were divided into four groups: Group I Control, Group II Trauma, Group III Mannitol, and Group IV 7.5% Hypertonic Saline. Rats in Group II were subject to head trauma only. Mannitol was injected intraperitoneally to rats in Group III after head trauma and 7.5% HS was injected intraperitoneally to rats in Group IV after head trauma. Rats were sacrificed 4 h after administration of mannitol or 7.5% HS, and the levels of MDA catalase and GSH-Px in brain tissues extracted from rats were determined. MDA levels in the trauma group were significantly increased compared with the control group (p<0.01), whereas there was a reduction in catalase and GSH-Px levels, although these differences were not significant. By contrast, in the mannitol group, MDA, catalase and GSH-Px levels were lower than the levels in the trauma group, and these reductions were statistically significant (p<0.05). The MDA, catalase and GSH-Px levels of the 7.5% HS group were lower than those of the trauma group; however, this reduction was not statistically significant. It was concluded that mannitol and 7.5% HS therapies that are used to reduce intracranial pressure and to increase the use of catalase, an antioxidant enzyme, and GSH-Px, are likely to reduce cellular damage by reducing the formation of MDA, the levels of which are known to be indicative of cellular level oxidant damage.