Neutrophil elastase inhibitor restores gut ischemia reperfusion-induced impairment of gut immunity with reduced plasma interleukin-6 concentrations in mice

A 30-Minute Supraceliac Aortic Clamping in the Rat Causes Death Due to an Inflammatory Response and Pulmonary Lesions

BACKGROUND

The treatment of thoracoabdominal aortic aneurysms through an open approach has general and pulmonary consequences of multiple etiologies. Our assumption was that the supraceliac aortic clamping needed for this operation causes a systemic inflammatory response associated with a pulmonary attack.

METHODS

We developed a model of 30-min supraceliac aortic clamping in Wistar rats weighing 300 g. After 90 min of reperfusion, the rats were sacrificed. The effects on the digestive tract wall were analyzed by measurement of the mucosal thickness/total thickness ratio. The effects on the mesenteric endothelial function were determined by an ex situ measurement of the arterial pressure/volume curves (third branch). The systemic consequences of the procedure were analyzed by dosing tumor necrosis factor alpha (TNFα), interleukin (IL)1β, and IL10 in the blood. The pulmonary consequences were analyzed by the measurement of macrophages, polymorphonuclear neutrophils (PNs), T lymphocyte infiltration, pulmonary apoptosis (TUNEL) and active caspase 3. The experimental scheme included 20 rats with ischemia-reperfusion (IR) and 20 control rats. An analysis of survival was carried out on 20 other rats (10 IR and 10 controls).

RESULTS

The results were expressed as average ± standard error of the mean. The statistical tests were Student's t-test and Mann-Whitney test. This visceral IR model decreased the ratio of the thickness of the intestinal mucosa compared with that of the control rats (0.77 ± 0.008 vs. 0.82 ± 0.009 [P < 0.001]). This local effect was not accompanied by any mesenteric endothelial dysfunction (P = 0.91). On a systemic level, IR increased TNFα (37.9 ± 1.5 vs. 28.2 ± 0.6 pg/mL; P < 0.0001), IL1β (67.1 ± 9.8 vs. 22.5 ± 5.6 pg/mL; P < 0.001), and IL10 (753.3 ± 96 vs. 3.7 ± 1.7 pg/mL; P < 0.0001). As regards the lungs, IR increased the parenchymal cellular infiltration by macrophages (6.8 ± 0.8 vs. 4.5 ± 0.4 cells per field; P < 0.05) and PNs (7.4 ± 0.5 vs. 6.2 ± 03 cells per field; P < 0.05). There was no increase in the pulmonary cellular apoptosis measured by TUNEL (P = 0.77) or in the caspase 3 activity (P = 0.59). The mortality of the visceral IR rats was 100% at 36 hr vs. 0% in the animals without IR.

CONCLUSIONS

This work showed that the inflammatory response to visceral IR had systemic and pulmonary effects which always results in the death in the rat.

Prophylactic inhibition of neutrophil elastase prevents the development of chronic neuropathic pain in osteoarthritic mice

Background

A subset of osteoarthritis (OA) patients experience joint pain with neuropathic characteristics. Mediators such as neutrophil elastase, a serine proteinase, may be released during acute OA inflammatory flares. We have previously shown that local administration of neutrophil elastase causes joint inflammation and pain via activation of proteinase-activated receptor-2 (PAR2). The aim of this study was to examine the contribution of endogenous neutrophil elastase and PAR2 to the development of joint inflammation, pain, and neuropathy associated with monoiodoacetate (MIA)-induced experimental OA.

Methods

MIA (0.3 mg/10 μl) was injected into the right knee joint of male C57BL/6 mice (20–34 g). Joint inflammation (edema, leukocyte kinetics), neutrophil elastase proteolytic activity, tactile allodynia, and saphenous nerve demyelination were assessed over 14 days post-injection. The effects of inhibiting neutrophil elastase during the early inflammatory phase of MIA (days 0 to 3) were determined using sivelestat (50 mg/kg i.p.) and serpinA1 (10 μg i.p.). Involvement of PAR2 in the development of MIA-induced joint inflammation and pain was studied using the PAR2 antagonist GB83 (5 μg i.p. days 0 to 1) and PAR2 knockout animals.

Results

MIA caused an increase in neutrophil elastase proteolytic activity on day 1 (P < 0.0001), but not on day 14. MIA also generated a transient inflammatory response which peaked on day 1 (P < 0.01) then subsided over the 2-week time course. Joint pain appeared on day 1 and persisted to day 14 (P < 0.0001). By day 14, the saphenous nerve showed signs of demyelination. Early treatment with sivelestat and serpinA1 blocked the proteolytic activity of neutrophil elastase on day 1 (P < 0.001), and caused lasting improvements in joint inflammation, pain, and saphenous nerve damage (P < 0.05). MIA-induced synovitis was reversed by early treatment with GB83 and attenuated in PAR2 knockout mice (P < 0.05). PAR2 knockout mice also showed reduced MIA-induced joint pain (P < 0.0001) and less nerve demyelination (P = 0.81 compared to saline control).

Conclusions

Neutrophil elastase and PAR2 contribute significantly to the development of joint inflammation, pain, and peripheral neuropathy associated with experimental OA, suggesting their potential as therapeutic targets.

Neutrophil elastase induces inflammation and pain in mouse knee joints via activation of proteinase-activated receptor-2

BACKGROUND AND PURPOSE

Neutrophil elastase plays a crucial role in arthritis. Here, its potential in triggering joint inflammation and pain was assessed, and whether these effects were mediated by proteinase-activated receptor-2 (PAR2).

EXPERIMENTAL APPROACH

Neutrophil elastase (5 μg) was injected into the knee joints of mice and changes in blood perfusion, leukocyte kinetics and paw withdrawal threshold were assessed. Similar experiments were performed in animals pretreated with the neutrophil elastase inhibitor sivelestat, the PAR2 antagonist GB83, the p44/42 MAPK inhibitor U0126 and in PAR2 receptor knockout (KO) mice. Neutrophil elastase activity was also evaluated in arthritic joints by fluorescent imaging and sivelestat was assessed for anti-inflammatory and analgesic properties.

KEY RESULTS

Intra-articular injection of neutrophil elastase caused an increase in blood perfusion, leukocyte kinetics and a decrease in paw withdrawal threshold. Sivelestat treatment suppressed this effect. The PAR2 antagonist GB83 reversed neutrophil elastase-induced synovitis and pain and these responses were also attenuated in PAR2 KO mice. The MAPK inhibitor U0126 also blocked neutrophil elastase-induced inflammation and pain. Active neutrophil elastase was increased in acutely inflamed knees as shown by an activatable fluorescent probe. Sivelestat appeared to reduce neutrophil elastase activity, but had only a moderate anti-inflammatory effect in this model.

CONCLUSIONS AND IMPLICATIONS

Neutrophil elastase induced acute inflammation and pain in knee joints of mice. These changes are PAR2-dependent and appear to involve activation of a p44/42 MAPK pathway. Blocking neutrophil elastase, PAR2 and p44/42 MAPK activity can reduce inflammation and pain, suggesting their utility as therapeutic targets.

Treatment with Recombinant Trichinella spiralis Cathepsin B-like Protein Ameliorates Intestinal Ischemia/Reperfusion Injury in Mice by Promoting a Switch from M1 to M2 Macrophages

Intestinal ischemia/reperfusion (I/R) injury, in which macrophages play a key role, can cause high morbidity and mortality. The switch from classically (M1) to alternatively (M2) activated macrophages, which is dependent on the activation of STAT6 signaling, has been shown to protect organs from I/R injuries. In the current study, the effects of recombinant Trichinella spiralis cathepsin B-like protein (rTsCPB) on intestinal I/R injury and the potential mechanism related to macrophage phenotypes switch were investigated. In a mouse I/R model undergoing 60-min intestinal ischemia followed by 2-h or 7-d reperfusion, we demonstrated that intestinal I/R caused significant intestinal injury and induced a switch from M2 to M1 macrophages, evidenced by a decrease in levels of M2 markers (arginase-1 and found in inflammatory zone protein), an increase in levels of M1 markers (inducible NO synthase and CCR7), and a decrease in the ratio of M2/M1 macrophages. RTsCPB reversed intestinal I/R-induced M2-M1 transition and promoted M1-M2 phenotype switch evidenced by a significant decrease in M1 markers, an increase in M2 markers, and the ratio of M2/M1 macrophages. Meanwhile, rTsCPB significantly ameliorated intestinal injury and improved intestinal function and survival rate of animals, accompanied by a decrease in neutrophil infiltration and an increase in cell proliferation in the intestine. However, a selective STAT6 inhibitor, AS1517499, reversed the protective effects of rTsCPB by inhibiting M1 to M2 transition. These findings suggest that intestinal I/R injury causes a switch from M2 to M1 macrophages and that rTsCPB ameliorates intestinal injury by promoting STAT6-dependent M1 to M2 transition.

Sivelestat mitigates severe acute pancreatitis in rats

AIM: To evaluate the therapeutic effect of sivelestat on severe acute pancreatitis (SAP) in a rat model by measuring the levels of serum neutrophil elastase (NE) and interleukin-6 (IL-6) and examining pancreatic pathological changes.

METHODS: SAP was induced in rats by retrograde injection of 5% sodium taurocholate into the biliopancreatic duct. Sivelestat was instilled continuously with an infusion pump in rats in the treatment group. Pancreatic pathological changes were evaluated by HE staining. The levels of serum NE and IL-6 were measured by ELISA. The level of serum amylase was measured using a biochemical analyzer.

RESULTS: The level of serum amylase was higher and pancreatic pathological changes were obvious in SAP rats compared to control rats. The levels of serum amylase, NE and IL-6 at various time points were significantly lower in treated rats than in SAP rats (3 h: 5636.22 ± 713.57 vs 5835.75 ± 681.52, 16.99 ± 3.28 vs 22.93 ± 4.74, 181.86 ± 36.56 vs 281.82 ± 30.79; 6 h: 5743.44 ± 624.93 vs 6253.66 ± 533.99, 23.63 ± 4.47 vs 31.81 ± 4.69, 184.15 ± 28.56 vs 319.39 ± 21.73; 12 h: 7098.93 ± 698.42 vs 8420.74 ± 779.72, 24.46 ± 5.02 vs 39.21 ± 6.23, 192.52 ± 37.65 vs 354.21 ± 23.72, all P < 0.05). The score of pancreatic pathological changes was significantly lower in treated rats than in SAP rats (P < 0.05). Serum levels of NE and IL-6 had a positive correlation with the score of pancreatic pathology.

CONCLUSION: Sivelestat could reduce serum levels of IL-6 and NE, mitigate pancreatic injury, and inhibit inflammatory reaction in rats with SAP.