The timing of endothelin and nitric oxide inhibition affects survival in a mice model of septic shock

Anti-sepsis protection of Xuebijing injection is mediated by differential regulation of pro- and anti-inflammatory Th17 and T regulatory cells in a murine model of polymicrobial sepsis

ETHNOPHARMACOLOGICAL RELEVANCE

Xuebijing injection (XBJ), a Chinese herbal medicine containing extracts from 5 herbs, is frequently used as an add-on with standard therapies to treat sepsis or septic shock with fewer side effects in China. Nonetheless, its mechanism of action on septic shock remains to be unveiled. We explored the differential effects of XBJ on subtypes of CD4+ T cell differentiation and septic shock protection in a murine model to understand the contribution of XBJ to regulation of the inflammation-immune axis function.

MATERIALS AND METHODS

In vitro T cell differentiation assays were performed to determine the effect of XBJ on CD4+ regulatory T cell and T helper cell differentiation. Besides, 2ml/kg, 6ml/kg- and 18ml/kg of XBJ were administered to different groups of septic mice once/day for 5 days after cecal ligation and puncture (CLP) surgeries. 36h after CLP, serum levels of pro-inflammatory cytokine TNF-α and IL-6 were determined with Elisa. Frequencies of CD4+ T cells were analyzed after staining with Tregs and T helper cell lineage specific antibodies by flow cytometer.

RESULTS

XBJ at 18ml/kg stimulated Treg differentiation and moderately inhibited Th17 differentiation in vitro. Accordingly, 18ml/kg XBJ facilitated the expansion of IL-10+ Tregs and normalized pro-inflammatory Th17 population in septic mice. This regimen also significantly reduced serum levels of inflammatory cytokines TNF-α and IL-6 in septic mice. Additionally, 18ml/kg XBJ injection effectively prevented neutrophil infiltration into the lung and kidney and improved survival in this septic shock model.

CONCLUSIONS

In summary, XBJ improves survival in septic shock partially through preventing cytokine storm, inhibiting inflammation and regulating the balance of Tregs and Th17 cells. Thus, higher dose of XBJ is a potential regimen to benefit septic shock patients.

Effects of endothelin and nitric oxide on cardiac muscle functions in experimental septic shock model

We aimed to investigate the possible roles of nitric oxide (NO) and endothelin on the changes of cardiac muscle function in both hyper- and hypodynamic septic shock periods. Cecal ligation and puncture was performed in 50 Wistar albino rats to induce septic shock. Changes in atrium and right ventricle papillary muscle contractions, atrium beat rate, adrenergic and cholinergic responses in these tissues were evaluated in vitro. Atrium beat rate increased in hypodynamic period ( p < 0.001) that was reversed by bosentan ( p < 0.001) and NG-nitro-l-arginine methylester (l-NAME; p < 0.05). Atrium contractions decreased in both hyper- and hypodynamic periods ( p < 0.001) that were partially ameliorated by bosentan in both periods ( p < 0.01) and only in hypodynamic period by l-NAME ( p < 0.001). l-NAME increased papillary muscle contractions in both periods ( p < 0.01), but bosentan increased it only in hyperdynamic period ( p < 0.01). Bosentan and l-NAME increased potency of isoproterenol on atrium beat rate in both periods and increased carbachol potency on atrium beat rate and atrium contraction amplitude only in hypodynamic period. Bosentan increased atrium contraction response to isoproterenol in hypodynamic period ( p < 0.05). Papillary muscle contraction response to isoproterenol increased in hypodynamic period ( p < 0.05). l-NAME increased papillary muscle contraction response to carbachol in both periods ( p < 0.01, p < 0.05, respectively). These results show that NO and endothelin may play a role in positive inotropic and negative chronotropic effects for atrium in septic shock. Bosentan and l-NAME may change potency and efficacy of isoproterenol and carbachol via upregulation of adrenergic and cholinergic receptors and/or through post receptor factors.

Endothelial glucocorticoid receptor is required for protection against sepsis

The glucocorticoid receptor (GR) is ubiquitously expressed on nearly all cell types, but tissue-specific deletion of this receptor can produce dramatic whole organism phenotypes. In this study we investigated the role of the endothelial GR in sepsis in vivo and in vitro. Mice with an endothelial-specific GR deletion and controls were treated with 12.5 mg/kg LPS and phenotyped. Mice lacking GR showed significantly increased mortality, more hemodynamic instability, higher nitric oxide levels, and higher levels of the inflammatory cytokines, tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) compared with controls. There were no differences in rates of apoptosis or macrophage recruitment between the two groups. Both endothelial nitric oxide synthase (eNOS) and inducible nitric oxide synthase (iNOS) expression were increased after LPS challenge in mice with endothelial GR deficiency, and aminoguanidine, a specific iNOS inhibitor in mice was able to rescue hemodynamic collapse in these animals. In vitro, human umbilical vein cells (HUVECs) subjected to GR knockdown by siRNA showed increased expression of eNOS at baseline that persisted after treatment with LPS. Both eNOS and iNOS mRNA was increased by qPCR. In HUVECs lacking GR, NF-κB levels and NF-κB-dependent genes tissue factor and IL-6 were increased compared with controls. Thus, endothelial GR is a critical regulator of NF-κB activation and nitric oxide synthesis in sepsis.

Effects of early administration of a novel anticholinergic drug on acute respiratory distress syndrome induced by sepsis

Background

Acute respiratory distress syndrome (ARDS) is the inflammatory disorder of the lung most commonly caused by sepsis. It was hypothesized that treating the lung with penehyclidine hydrochloride (PHC), a new type of hyoscyamus drug, early in the development of sepsis could diminish the lung dysfunction.

Material/Methods

Sprague-Dawley rats were divided into 4 groups: 1) a control group; 2) a sham-operated group; 3) a cecal ligation and puncture (CLP) group; 4) a PHC-treated group. One hour after CLP surgery, rats were either untreated or treated with PHC via intraperitoneal injection. Lung wet/dry weight ratio, bronchoalveolar lavage fluid (BALF), serum tumor necrosis factor (TNF-α), interleukin 6 (IL-6), interleukin 10 (IL-10), total nitrite/nitrate (NOx), superoxide dismutase (SOD), malondialdehyde (MDA) in lung tissues, and pulmonary functions were examined 24 hour after surgery. Another 60 rats were randomly assigned to 4 equal groups to observe survival status 96 hours after surgery.

Results

Treatment of PHC markedly decreased TNF-α, IL-6, NOx, SOD, MDA content, protein concentration in BALF, and lung wet/dry weight ratio and enhanced SOD activity (p<0.05), which are indicative of PHC-induced suppression in the pathogenesis of ARDS caused by sepsis. In comparison to group CLP/saline, plasma IL-10 level markedly increased in group CLP/PHC. In PHC-treated groups, the administered PHC had a significant protective effect on the lung dysfunction induced by sepsis.

Conclusions

We conclude that administration of PHC at the time of a systemic insult can protect the lung from the damaging effects of sepsis.

Protective effects of penehyclidine hydrochloride on septic mice and its mechanism

Anticholinergics can have protective effects against septic shock. Penehyclidine hydrochloride (PHC) is a novel anticholinergic agent exhibiting few cardiovascular side effects. This work explored the protective effects of PHC on septic mice and its mechanism. Mice were randomly divided into four groups: sham control, cecal ligation and puncture (CLP), CLP/0.3 mg/kg PHC, and CLP/0.45 mg/kg PHC, with 10 mice in each. One hour before surgery, PHC-treated mice received an intraperitoneal injection of PHC and an equal volume of saline in the other two groups. Blood plasma and tissue samples were collected at 12 h after surgery. Serum TNF-alpha, histopathology, superoxide dismutase (SOD), malondialdehyde (MDA), and expression of iNOS in lung and hepatic tissues were examined. Another 40 mice were randomly assigned to four equal groups to observe survival status during 96 h after operation. Treatment of 0.45 mg/kg PHC markedly decreased TNF-alpha, MDA content, and iNOS mRNA expression, and enhanced SOD activity (P < 0.05 and P < 0.01). Treatment of 0.45 mg/kg PHC might have a protective effect against sepsis. Its action mechanisms are probably involved in the inhibition of inflammatory factor production and suppression of iNOS mRNA expression and lipidperoxidation.

Deficiency of mitogen-activated protein kinase phosphatase-1 results in iNOS-mediated hypotension in response to low-dose endotoxin

Mitogen-activated protein kinase phosphatase-1 (MKP-1) is essential in limiting the proinflammatory response to lipopolysaccharide (LPS). We hypothesized that Mkp-1(-/-) mice would respond to low-dose LPS with a fall in blood pressure due to augmented expression of inducible nitric oxide (NO) synthase (iNOS). To test this hypothesis, Mkp-1(-/-) mice and their wild-type littermates were treated with 10 microg/kg iv LPS, and mean arterial blood pressure (MAP) and exhaled NO production (exNO) were measured. Tissues were harvested for an assessment of iNOS protein levels. Wild-type mice had no change in MAP or exNO during the experimental period, whereas Mkp-1(-/-) mice had a fall (P < 0.005) in MAP [79 +/- 5% of baseline (BL)] and an increase (P < 0.01) in exNO (266 +/- 50% of BL) after 150 min. The tissue levels of iNOS were greater in Mkp-1(-/-) than in wild-type mice. In additional experiments, 60 min after LPS treatment, Mkp-1(-/-) and wild-type mice were given N(omega)-nitro-l-arginine methyl ester (l-NAME) or aminoguanidine, and MAP and exNO were monitored for 90 min. Treatment with l-NAME prevented the LPS-induced increase in exNO and decrease in MAP but resulted in decreased exNO and elevated MAP in wild-type mice. Aminoguanidine prevented the increase in exNO and the fall in MAP caused by LPS in Mkp-1(-/-) mice, without significantly affecting MAP or exNO in wild-type mice. These results demonstrate that a deficiency of MKP-1 results in an exaggerated hypotensive response to LPS mediated by augmented iNOS expression. We speculate that defects in the Mkp-1 gene may increase susceptibility for the development of septic shock.

Endothelin receptor antagonist bosentan improves survival in a murine caecal ligation and puncture model of septic shock

The role of endothelin peptides was evaluated on survival and organ injury in a model of polymicrobial sepsis, induced by caecal ligation and puncture with particular emphasis on the timing of the administration of its blocker bosentan in Swiss albino mice (20-40 g). The cardiovascular response pattern in this experimental model was characterized by an early, "hyperdynamic" phase starting at 5 h, followed by a late but "hypodynamic" phase that commence after 20 h, provided that the animals are "resuscitated" by injecting 1 ml of saline i.p. at the end of the surgery. However, if saline resuscitation is omitted, then only hypodynamic pattern is observed starting at 5 h without any hyperdynamic phase. Thus, mice were first allocated into saline-resuscitated or unresuscitated groups and endothelin receptor antagonist bosentan (30 mg kg(-1), i.p., either 5 or 20 h after caecal ligation and puncture) was then administered. The control animals received the solvent of bosentan (i.e., saline: %0.9 NaCl, w/v). The survival rates in each group (n=14) were recorded over the following 144 h. In unresuscitated mice, the overall survival at 144 h was 14.3% in controls while bosentan treatment at 5 h (78.6%, P=0.0018) or 20 h (64.3%, P=0.0183) have both significantly improved the survival. However, in saline-resuscitated mice, bosentan administered at 20 h has significantly improved the survival (71.4%, P=0.0213) while its administration at 5 h has yielded exactly the same percent of survival (i.e., 21.4%) as observed in control animals. The beneficial effects of bosentan in preventing the tissue injury due to caecal ligation and puncture were also observed histopathologically in liver, spleen and kidney. Therefore, we concluded that the blockade of endothelin receptors by using bosentan during the later (hypodynamic) stages of septic shock is a promising therapeutic manoeuvre.

The effects of selective nitric oxide synthase blocker on survival, mesenteric blood flow and multiple organ failure induced by zymosan1

BACKGROUND

Circulatory failure in multiple organ dysfunction syndromes (MODS) is characterized with systemic vasodilation, diminished blood flow to various vascular beds. The aim of this study was to investigate the effects of selective inhibition of nitric oxide on the mesenteric arterial blood flow (MABF), survival and organ injury of the liver, kidney, lung and spleen in zymosan-induced MODS.

MATERIALS AND METHODS

Forty Swiss albino mice (20-40 g), 7 to 9 weeks old, were obtained. Animals were randomly divided into four groups. The first group were treated intraperitoneally (i.p) with vehicle (saline) and served as a sham group for aminoguanidine (AG) (n=10). The second group was treated with zymosan (500 mg/kg, suspended in saline solution, i.p). The mice in the third and fourth group received AG (15 mg/kg) 1 h and 6 h after zymosan or saline administration, respectively. Eighteen hours after the administration of zymosan, animals were assessed for MODS described subsequently. The signals from the flowmeter were also recorded on mesenteric arterial blood flow values.

RESULTS

In zymosan-treated animals, the MABF was significantly lower than that of solvent (saline)-treated controls (ml min(-1), controls: 4.6 +/- 0.6; zymosan: 1.6 +/- 0.9, P <0.05). When animals were treated with AG, there were no significant differences in MABF values between AG group and solvent (saline)-treated control group. However AG prevented zymosan-induced mesenteric MABF decrease. Treatment with aminoguanidine also decreased mortality.

CONCLUSION

AG is capable of inhibiting both the induction and the activity of the already iNOS; it remains a potential therapeutic agent in patients with MODS.

A new therapeutic approach for the treatment of sepsis

Despite important advances in understanding its pathophysiology, therapy for septic shock remains largely symptomatic and supportive. Aiming to elevate the systemic arterial blood pressure by using vasoconstrictor manoeuvers are preferred without paying much attention to the ischaemia produced at the peripheral tissues. Since, these maneuvers proved no remarkable success in reducing the mortality up to date, we now propose a different perspective in this manuscript. Although it is not always easy to distinguish the different phases of septic shock, at least two fundamentally different phases can be distinguished, i.e. (i) hyperdynamic phase and (ii) hypodynamic phase mandating the adoption of vasodilative and vasoconstrictive interventions, consequently. Additionally, endothelium-derived vasodilator and vasoconstrictor substances such as nitric oxide and endothelin play key roles in systemic inflammatory response syndrome that lead to fatal multiple organ dysfunction. Therefore, we hypothesize that the inhibition of nitric oxide production during earlier phases of septic shock combined with the blockade of endothelin receptors at later stages appear feasible and a novel strategy for the therapy of septic shock.

Protection against murine endotoxemia by treatment with Ruta chalepensis L., a plant with anti-inflammatory properties

The anti-inflammatory effect of the extract of Ruta Chalepensis L. (Rutaceae) on the course of lethal endotoxemia in BALB/c mice was studied. When administered by gavage as 1 g/kg per day starting 14 or 7 days prior to injection of 0.75 mg endotoxin (LPS: lipopolysaccharide), the extract markedly reduced lethality (32.5% in both experiments versus approximately 85% of the control mice). A delay in lethality, but not cumulative lethality, was observed when prophylaxis was given 24 and 1 h prior to LPS challenge. The effect was associated with reduced LPS-induced blood levels of nitrite, an indicator of nitric oxide production. In contrast, the blood levels of tumour necrosis factor, interleukin 6 and interleukin 10 did not differ significantly from those of controls given LPS alone. These data show that Ruta Chalepensis L. possesses powerful immunopharmacological properties that make it capable of counteracting the lethal effects of high doses of LPS in vivo.