Sivelestat suppresses iNOS gene expression in proinflammatory cytokine-stimulated hepatocytes

Sivelestat ameliorates sepsis-induced myocardial dysfunction by activating the PI3K/AKT/mTOR signaling pathway

The cardioprotective role of sivelestat, a neutrophil elastase inhibitor, has already been demonstrated, but the underlying molecular mechanism remains unclear. This study aimed to explore the mechanism underlying the role of sivelestat in sepsis-induced myocardial dysfunction (SIMD). We found that sivelestat treatment remarkably improved the viability and suppressed the apoptosis of lipopolysaccharide (LPS)-stimulated H9c2 cells. In vivo, sivelestat treatment was associated with an improved survival rate; reduced serum cTnT, TNF-α, IL-1β levels and myocardial TNF-α and IL-1β levels; ameliorated cardiac function and structure; and reduced cardiomyocyte apoptosis. Moreover, sivelestat treatment substantially increased Bcl-2 expression and suppressed caspase-3 and Bax expression in LPS-induced H9c2 cells and in the heart tissues of septic rats. Furthermore, the phosphatidylinositol 3-kinase/protein kinase B/mechanistic target of rapamycin (PI3K/AKT/mTOR) signaling pathway was activated both in vitro and in vivo. The protective effect of sivelestat against SIMD was reversed by the PI3K inhibitor LY294002. In summary, sivelestat can protect against SIMD by activating the PI3K/AKT/mTOR signaling pathway.

Levosimendan pretreatment improves survival of septic rats after partial hepatectomy and suppresses iNOS induction in cytokine-stimulated hepatocytes

We evaluated the survival effects and biochemical profiles of levosimendan in septic rats after partial hepatectomy and investigated its effects in cultured hepatocytes. Thirty-two rats underwent 70% hepatectomy and were randomised equally into four groups, followed by lipopolysaccharide (LPS) injection (250 µg/kg, i.v.) after 48 h. Levosimendan was given (i.p.) 1 h before LPS injection [group (A) levosimendan 2 mg/kg; (B) 1; (C) 0.5; (D) vehicle]. Survival at 7 days was increased significantly in group A compared with that in group D [A: 63%; B: 38%; C: 13%; D: 0%]. In serum, levosimendan decreased the level of tumour necrosis factor-α, interleukin (IL)-1β, IL-6 and nitric oxide (NO). In remnant livers, levosimendan inhibited inducible nitric oxide synthase (iNOS) gene expression. In primary cultured rat hepatocytes stimulated by IL-1β, levosimendan suppressed NO production by inhibiting iNOS promoter activity and stability of its mRNA.

The neutrophil elastase inhibitor, sivelestat, attenuates sepsis-related kidney injury in rats

Sepsis-induced acute kidney injury (AKI) represents a major cause of mortality in intensive care units. Sivelestat, a selective inhibitor of neutrophil elastase (NE), can attenuate sepsis-related acute lung injury. However, whether sivelestat can preserve kidney function during sepsis remains unclear. In this study, we thus examined the effects of sivelestat on sepsis-related AKI. Cecal ligation and puncture (CLP) was performed to induce multiple bacterial infection in male Sprague-Dawley rats, and subsequently, 50 or 100 mg/kg sivelestat were administered by intraperitoneal injection immediately after the surgical procedure. In the untreated rats with sepsis, the mean arterial pressure (MAP) and glomerular filtration rate (GFR) were decreased, whereas serum blood urea nitrogen (BUN) and neutrophil gelatinase-associated lipocalin (NGAL) levels were increased. We found that sivelestat promoted the survival of the rats with sepsis, restored the impairment of MAP and GFR, and inhibited the increased BUN and NGAL levels; specifically, the higher dose was more effective. In addition, sivelestat suppressed the CLP-induced macrophage infiltration, the overproduction of pro-inflammatory mediators (tumor necrosis factor-α, interleukin-1β, high-mobility group box 1 and inducible nitric oxide synthase) and serine/threonine kinase (Akt) pathway activation in the rats. Collectively, our data suggest that the inhibition of NE activity with the inhibitor, sivelestat, is beneficial in ameliorating sepsis-related kidney injury.

pyroGlu-Leu inhibits the induction of inducible nitric oxide synthase in interleukin-1β-stimulated primary cultured rat hepatocytes

Pyroglutamyl leucine (pyroGlu-Leu), which is a peptide isolated from wheat gluten hydrolysate, has been reported to be a hepatoprotective compound in acute liver failure. In inflamed liver, proinflammatory cytokines including interleukin (IL)-1β and tumor necrosis factor (TNF)-α stimulate the induction of inducible nitric oxide synthase (iNOS). Excess production of nitric oxide (NO) by iNOS is an inflammatory biomarker in liver injury. We examined proinflammatory cytokine-stimulated hepatocytes as a simple "in vitro inflammation model" to determine liver protective effects of pyroGlu-Leu and its mechanisms of action. We hypothesized that pyroGlu-Leu inhibits the induction of iNOS gene expression, resulting in the attenuation of hepatic inflammation. Hepatocytes were isolated from rats by collagenase perfusion and cultured. Primary cultured cells were treated with IL-1β in the presence or absence of pyroGlu-Leu. The induction of iNOS and its signaling pathway were analyzed. IL-1β stimulated the enhancement of NO production in hepatocytes and this effect was inhibited by pyroGlu-Leu. pyroGlu-Leu decreased the expression of iNOS protein and its mRNA. Transfection experiments with iNOS-luciferase constructs revealed that pyroGlu-Leu inhibited both of iNOS promoter transactivation and its mRNA stabilization. pyroGlu-Leu also decreased the expression of an iNOS gene antisense transcript, which is involved in iNOS mRNA stability. However, pyroGlu-Leu had no effects on IκB degradation and NF-κB activation. Results demonstrate that pyroGlu-Leu inhibited the induction of iNOS gene expression at transcriptional and post-transcriptional steps through IκB/NF-κB-independent pathway, leading to the prevention of NO production. pyroGlu-Leu may have therapeutic potential for liver injury through the suppression of iNOS.

Temporal and spatial dependence of inflammatory biomarkers and suppression by fluvastatin in dextran sodium sulfate-induced rat colitis model

BACKGROUND

Dextran sodium sulfate (DSS)-induced colitis in rats is widely used as an experimental model for elucidating the etiology of ulcerative colitis (UC) and developing its novel remedy. We investigated the temporal and spatial changes in inflammatory mediators such as tumor necrosis factor (TNF)-α and inducible nitric oxide synthase (iNOS) in the regions of rectum and distal colon and examined whether statins, which were designed to lower plasma cholesterol levels, influenced those mediators.

METHODS

Colitis was induced in rats by oral administration of 5 % DSS for 5 days, followed by 2 % DSS for 10 days. 5 % DSS rats were treated with fluvastatin (20 mg/kg) concomitantly for 5 days. The expression of inflammatory mediators of a sequence of four regions in rectum (R) and distal colon (D0, D1, and D2) was determined by quantitative RT-PCR.

RESULTS

The peak of colitic damage, which was confirmed clinically and histopathologically, was found on days 4-6. The expression of TNF-α, iNOS, cytokine-induced neutrophil chemoattractant-1, interleukin (IL)-1β, and IL-6 mRNA increased in R time dependently, showing the peak on days 4-6, and then decreased thereafter. The levels of mRNAs reduced from R to D0, D1, and D2 region dependently. Fluvastatin decreased the expression of these markers in addition to the prevention of DSS-induced damage.

CONCLUSIONS

Results demonstrated that the expression of inflammatory biomarkers had time and region specificity and was markedly inhibited by fluvastatin. To obtain a precise drug effect for UC, it is important to elucidate the temporal and spatial dependence of inflammatory biomarkers in DSS colitis model.

Fluvastatin inhibits the induction of inducible nitric oxide synthase, an inflammatory biomarker, in hepatocytes

AIM

Statins (3-hydroxy-3-methylglutaryl coenzyme A [HMG-CoA] reductase inhibitors), which were originally designed to lower plasma cholesterol levels, are increasingly recognized as anti-inflammatory agents. In the inflamed liver, pro-inflammatory cytokines stimulate the induction of inducible nitric oxide synthase (iNOS). Overproduction of NO by iNOS has been implicated as a factor in liver injury. We examined pro-inflammatory cytokine-stimulated hepatocytes as a simple in vitro injury model to determine liver-protective effects of statins. We hypothesized that statins are involved in the downregulation of iNOS, resulting in decreased hepatic inflammation.

METHODS

Hepatocytes were isolated from rats by collagenase perfusion and centrifugation. Primary cultured hepatocytes were treated with interleukin (IL)-1β in the presence or absence of fluvastatin. The induction of iNOS and its signaling pathway were analyzed.

RESULTS

IL-1β produced increased levels of NO. This effect was inhibited by fluvastatin, which exerted its maximal effects at 100 μM. Fluvastatin decreased the levels of iNOS protein and its mRNA expression. Fluvastatin had no effects on IκB degradation and nuclear factor-κB activation. However, fluvastatin inhibited the upregulation of type I IL-1 receptor mRNA and protein expression. Transfection experiments demonstrated that fluvastatin suppressed iNOS induction by the inhibition of promoter transactivation and mRNA stabilization. Fluvastatin reduced the expression of an iNOS gene antisense-transcript, which is involved in iNOS mRNA stability.

CONCLUSION

Results indicate that fluvastatin inhibits the induction of iNOS at both transcriptional and post-transcriptional steps, leading to the prevention of NO production. Fluvastatin may provide therapeutic potential in iNOS induction involved in various liver injuries.

Japanese herbal medicine, inchinkoto, inhibits inducible nitric oxide synthase induction in interleukin-1β-stimulated hepatocytes

AIM

  A herbal medicine, kampo inchinkoto (TJ-135), is used to treat jaundice and liver fibrosis in patients with cirrhosis. In the inflamed liver, proinflammatory cytokines stimulate the induction of inducible nitric oxide synthase (iNOS) gene expression. Over-production of nitric oxide (NO) by iNOS has been implicated as a factor in liver injury. We examined interleukin (IL)-1β-stimulated hepatocytes as a simple in vitro injury model to determine liver-protective effects of TJ-135. The objective was to investigate whether TJ-135 influences iNOS induction and to determine its mechanism.

METHODS

  Primary cultured rat hepatocytes were treated with IL-1β in the presence or absence of TJ-135. The induction of iNOS and its signaling pathway were analyzed.

RESULTS

  IL-1β produced increased levels of NO. This effect was inhibited by TJ-135, which exerted its maximal effects at 3 mg/mL. TJ-135 decreased the levels of iNOS protein and its mRNA expression. Experiments with nuclear extracts revealed that TJ-135 inhibited the translocation of nuclear factor-κB (NF-κB) to the nucleus and its DNA binding. TJ-135 also inhibited the activation of Akt, resulting in the reduction of type I IL-1 receptor mRNA and protein expression. Transfection experiments with iNOS promoter-luciferase constructs demonstrated that TJ-135 suppressed iNOS induction by inhibition of promoter transactivation and mRNA stabilization. TJ-135 reduced the expression of an iNOS gene antisense-transcript. Delayed administration or withdrawal of TJ-135 after IL-1β addition also inhibited iNOS induction.

CONCLUSIONS

  RESULTS indicate that TJ-135 inhibits the induction of iNOS at both transcriptional and post-transcriptional steps, leading to the prevention of NO production. TJ-135 may have therapeutic potential for various liver injuries through the suppression of iNOS induction.