Relationship between vascular reactivity and expression of HMGB1 in a rat model of septic aorta

A Nutraceutical Product Based on a Mixture of Algae and Extra Virgin Olive Oils and Olive Leaf Extract Attenuates Sepsis-Induced Cardiovascular and Muscle Alterations in Rats

Nutraceuticals are products of natural origin widely used for the treatment and/or prevention of some chronic diseases that are highly prevalent in Western countries, such as obesity or type II diabetes, among others. However, its possible use in the prevention of acute diseases that can put life at risk has been poorly studied. Sepsis is an acute condition that causes cardiovascular and skeletal muscle damage due to a systemic inflammatory state. The aim of this work was to evaluate the possible beneficial effect of a new nutraceutical based on a mixture of algae oil (AO) and extra virgin olive oil (EVOO) supplemented with an olive leaf extract (OLE) in the prevention of cardiovascular alterations and skeletal muscle disorders induced by sepsis in rats. For this purpose, male Wistar rats were treated with the nutraceutical or with water p.o. for 3 weeks and after the treatment they were injected with 1mg/kg LPS twice (12 and 4 h before sacrifice). Pretreatment with the nutraceutical prevented the LPS-induced decrease in cardiac contractility before and after the hearts were subjected to ischemia-reperfusion. At the vascular level, supplementation with the nutraceutical did not prevent hypotension in septic animals, but it attenuated endothelial dysfunction and the increased response of aortic rings to the vasoconstrictors norepinephrine and angiotensin-II induced by LPS. The beneficial effects on cardiovascular function were associated with an increased expression of the antioxidant enzymes SOD-1 and GSR in cardiac tissue and SOD-1 and Alox-5 in arterial tissue. In skeletal muscle, nutraceutical pretreatment prevented LPS-induced muscle proteolysis and autophagy and significantly increased protein synthesis as demonstrated by decreased expression of MURF-1, atrogin-1, LC3b and increased MCH-I and MCH -IIa in gastrocnemius muscle. These effects were associated with a decrease in the expression of TNFα, HDAC4 and myogenin. In conclusion, treatment with a new nutraceutical based on a mixture of AO and EVOO supplemented with OLE is useful to prevent cardiovascular and muscular changes induced by sepsis in rats. Thus, supplementation with this nutraceutical may constitute an interesting strategy to reduce the severity and mortality risk in septic patients.

Involvement of Toll-Like Receptor 4 in Decreased Vasopressor Response Following Trauma/Hemorrhagic Shock

OBJECTIVES:

Refractory vascular failure due to the inability of vascular smooth muscle to respond to vasoconstrictors such as phenylephrine is a final common pathway for severe circulatory shock of any cause, including trauma/hemorrhagic shock. Increased inflammation, Toll-like receptor 4 activation, and decreased response of the alpha-1 adrenergic receptors which control vascular tone have been reported in trauma/hemorrhagic shock.

HYPOTHESIS:

In trauma/hemorrhagic shock, Toll-like receptor 4 activation contributes to vascular failure via decreased bioavailability of adrenergic receptors.

DESIGN AND MEASUREMENTS:

Trauma/hemorrhagic shock was induced in Wistar rats (laparotomy combined with mean arterial pressure at 40 mm Hg for 90 min followed by 2 hr resuscitation with Lactated Ringers solution). To inhibit Toll-like receptor 4, resatorvid (TAK-242) and resveratrol were used, and plasma was collected. Smooth muscle cells were incubated with lipopolysaccharide (10 ng/mL) or plasma. Inflammatory cytokines were screened using dot-blot. Toll-like receptor 4 and nuclear factor κB activation and cellular localization of the alpha-1 adrenergic receptor were measured by immunofluorescence imaging and Western blot analysis. Clustered regularly interspaced short palindromic repeats/Cas9 was used to knock out Toll-like receptor 4, and calcium influx following stimulation with phenylephrine was recorded.

MAIN RESULTS:

Trauma/hemorrhagic shock caused a decreased response to phenylephrine, whereas Toll-like receptor 4 inhibition improved blood pressure. Trauma/hemorrhagic shock plasma activated the Toll-like receptor 4/nuclear factor κB pathway in smooth muscle cells. Double labeling of Toll-like receptor 4 and the alpha-1 adrenergic receptor showed that these receptors are colocalized on the cell membrane. Activation of Toll-like receptor 4 caused cointernalization of both receptors. Calcium influx was impaired in cells incubated with trauma/hemorrhagic shock plasma but restored when Toll-like receptor 4 was knocked out or inhibited.

CONCLUSIONS:

Activation of the Toll-like receptor 4 desensitizes vascular smooth muscle cells to vasopressors in experimental trauma/hemorrhagic shock by reducing the levels of membrane alpha-1 adrenergic receptor.

Lipopolysaccharide exposure modulates the contractile and migratory phenotypes of vascular smooth muscle cells

INTRODUCTION

Sepsis survivors are at higher risk for cardiovascular events. Lipopolysaccharide (LPS) activates Toll-like receptor 4 (TLR4) in sepsis. Activation of TLR4 modulates vascular smooth muscle cells (VSMCs) phenotype and contributes to cardiovascular changes after sepsis.

AIM

Investigate changes in VSMCs phenotype caused by LPS-induced TLR4 activation.

METHODS

Rat VSMCs were incubated with LPS. Two incubation conditions were used in cell contraction and migration assays: acute stimulation - LPS stimulus was initiated at the beginning of the assay and maintained throughout; and preconditioning - LPS stimulation was applied prior to the assay then discontinued. Nitric oxide (NO) production, mRNA expression of cytokines and phenotype markers, and interleukin (IL)-6 production were evaluated.

KEY FINDINGS

LPS increased gene expression of IL-1β, IL-6, TNFα and MCP-1 (p < .001), of secretory phenotype markers collagen and vimentin (p < .0479) and of the contractile marker smooth muscle 22α (SM22α) (p = .0067). LPS exposure increased IL-6 secretion after 24 and 48 h (p < .0001), and NO at 8 and 24 h (p < .0249) via inducible nitric oxide synthase (iNOS), as demonstrated by a decrease in NO after incubation with aminoguanidine. Acute stimulation with LPS reduced migration and contraction in a NO-dependent manner, while preconditioning with LPS increased both in an IL-6-dependent manner.

SIGNIFICANCE

LPS affects VSMCs by modulating their secretory, contractile and migratory phenotypes. LPS acute stimulation of VSMCs promoted a NO-dependent reduction in migration and contraction, while preconditioning with LPS promoted IL-6-dependent increases in migration and contraction, evidencing that VSMCs can present phenotype modifications that persist after sepsis, thereby contributing to postsepsis cardiovascular events.

Platonin mitigates vascular hyporeactivity of thoracic aorta in septic rats

BACKGROUND

Vascular hyporeactivity contributes to hemodynamic alterations and circulatory failure in severe sepsis. Among the identified mechanisms, inflammation and oxidative stress are the most crucial ones in mediating the development of vascular hyporeactivity induced by sepsis. Platonin, a photosensitive dye and an antioxidant, possesses potent antiinflammation effects. We elucidated whether platonin could mitigate vascular hyporeactivity of thoracic aorta in septic rats.

MATERIAL AND METHODS

Adult male Sprague-Dawley rats were randomized to receive sham operation (Sham), Sham plus platonin (100 μg/kg), cecal ligation and puncture (CLP), or CLP plus platonin (10, 50, or 100 μg/kg) and designated as the Sham, P, CLP, CLP + P(10), CLP + P(50), and CLP + P(100) group, respectively (n = 6 in each group). After maintaining for 12 hours, surviving rats were euthanized and thoracic aorta was isolated and vascular reactivity of aortic rings was determined.

RESULTS

Vascular reactivity induced by vasoconstrictors phenylephrine and angiotensin II of the Sham and the P groups (n = 6 in both groups) were similar, whereas vascular reactivity of the CLP group (n = 5) were significantly lower than those of the Sham group (both P < 0.001). Of note, vascular reactivity induced by phenylephrine and angiotensin II of the CLP + P(10) group (n = 5) and the CLP group were not significantly different. In contrast, vascular reactivity induced by phenylephrine and angiotensin II of the CLP + P(50) and the CLP + P(100) groups (n = 6 in both groups) were significantly higher than those of the CLP group (phenylephrine: P = 0.024 and 0.017; angiotensin II: P = 0.031 and 0.036).

CONCLUSION

Platonin could mitigate vascular hyporeactivity of thoracic aorta in septic rats.

Continuous hemodiafiltration therapy reduces damage of multi-organs by ameliorating of HMGB1/TLR4/NFκB in a dog sepsis model

In the present study, we investigated whether CVVH can reduce HMGB1, TLR4, NF-κB and other serum cytokine levels, preventing organ injury in a dog sepsis model. A total of 10 dogs were injected with LPS and treated with either CVVH group (n = 5) or nothing (Control, n = 5) for 24 h. EILSA was used for examining the concentration of TNF-α, IL-6, HMGB 1 and TLR4. The histological change of lung, liver and kidney tissues was determined. The mRNA expression of HMGB1, TLR4 and NF-κB was examined by RT-PCR. The protein of HMGB1 and phosphated NF-κB was examined by Western-blot. The levels of serum HMGB1 came to the peak at 8 h, 16 h and then declined. The LPS-induced increase in HMGB1 level was suppressed by CVVH compared with Control. Likewise, serum TNF-α and IL-6 levels decreased with CVVH along with a significant improvement in the function of main organs. Histologic examination revealed significant reduction in inflammation in lung; liver and kidney tissues harvested 24 h after CVVH compared with Control. The mRNA of HMGB1, TLR4 and NF-κB in the kidney was expressed at high level after LPS administration, which was significantly decreased by CVVH. The increased protein expression of HMGB1 and phosphated NF-κB was reduced after CVVH compared with control. CVVH by reducing the level of HMGB1, TLR4, NF-κB and other cytokines could weaken the cascade of cytokines and restore the immune system, and reduce the damage of important organs in sepsis.