Pentoxifylline attenuates pulmonary inflammation and neutrophil activation in experimental acute pancreatitis

Pentoxifylline treats Aspergillus fumigatus keratitis by reducing fungal burden and suppressing corneal inflammation

Fungal keratitis (FK) is a blinding ocular disease, which mainly results from fungal damage and excessive inflammation. Pentoxifylline, a kind of methylxanthine, has been discovered to have anti-inflammatory properties in various infectious diseases, hinting a potential therapeutic effect on treating corneal fungal infection. Whereas, the therapeutic impact of pentoxifylline on fungal keratitis is still uncertain. This study investigated the antifungal capability against Aspergillus fumigatus and the anti-inflammatory role of pentoxifylline by activating nuclear factor, erythroid 2 like 2 (Nrf2)/heme oxygenase1 (HO1) pathway in the process of FK. In our research, we demonstrated that pentoxifylline could effectively inhibit fungal growth and inflammatory reaction. Pentoxifylline reduced the production of pro-inflammatory factors by stimulating the Nrf2/HO1 pathway. Although there was no statistical difference between the curative efficacy of pentoxifylline and natamycin application to FK, pentoxifylline could promote corneal epithelial repair and was less toxicity to the ocular surface than natamycin. In conclusion, pentoxifylline performs antifungal and anti-inflammatory effects by lessening the fungus burden and activating the Nrf2/HO1 pathway, hinting that it has the potential to be a new therapeutic medication for Aspergillus fumigatus keratitis.

Acinar cell NLRP3 inflammasome and gasdermin D (GSDMD) activation mediates pyroptosis and systemic inflammation in acute pancreatitis

BACKGROUND AND PURPOSE

Pyroptosis is a lytic form of pro-inflammatory cell death characterised as caspase 1 dependent with canonical NLRP3 inflammasome-induced gasdermin D (GSDMD) activation. We aimed to investigate the role of acinar pyroptotic cell death in pancreatic injury and systemic inflammation in AP.

EXPERIMENTAL APPROACH

Pancreatic acinar pyroptotic cell death pathway activation upon pancreatic toxin stimulation in vitro and in vivo was investigated. Effects of pharmacological (NLRP3 and caspase-1 inhibitors), constitutive (Nlrp3^-/- , Casp1^-/- and Gsdmd^-/- ) and acinar cell conditional (Pdx1^Cre Nlrp3^Δ/Δ and Pdx1^Cre Gsdmd^Δ/Δ ) genetic inhibition on pyroptotic acinar cell death, pancreatic necrosis and systemic inflammation were assessed using mouse AP models (caerulein, sodium taurocholate and l-arginine). Effects of Pdx1^Cre Gsdmd^Δ/Δ versus myeloid conditional knockout (Lyz2^Cre Gsdmd^Δ/Δ ) and Gsdmd^-/- versus receptor-interacting protein 3 (RIP3) inhibitor were compared in CER-AP.

KEY RESULTS

There was consistent pyroptotic acinar cell death upon pancreatic toxin stimulation both in vitro and in vivo, which was significantly reduced by pharmacological or genetic pyroptosis inhibition. Pdx1^Cre Gsdmd^Δ/Δ but not Lyz2^Cre Gsdmd^Δ/Δ mice showed significantly reduced pyroptotic acinar cell death, pancreatic necrosis and systemic inflammation in caerulein-AP. Co-application of RIP3 inhibitor on Gsdmd^-/- mice further increased protection on caerulein-AP.

CONCLUSION AND IMPLICATIONS

This work demonstrates a critical role for NLRP3 inflammasome and GSDMD activation-mediated pyroptosis in acinar cells, linking pancreatic necrosis and systemic inflammation in AP. Targeting pyroptosis signalling pathways holds promise for specific AP therapy.

Alleviation of acute pancreatitis-associated lung injury by inhibiting the p38 mitogen-activated protein kinase pathway in pulmonary microvascular endothelial cells

BACKGROUND

Previous reports have suggested that the p38 mitogen-activated protein kinase signaling pathway is involved in the development of severe acute pancreatitis (SAP)-related acute lung injury (ALI). Inhibition of p38 by SB203580 blocked the inflammatory responses in SAP-ALI. However, the precise mechanism associated with p38 is unclear, particularly in pulmonary microvascular endothelial cell (PMVEC) injury.

AIM

To determine its role in the tumor necrosis factor-alpha (TNF-α)-induced inflammation and apoptosis of PMVECs in vitro. We then conducted in vivo experiments to confirm the effect of SB203580-mediated p38 inhibition on SAP-ALI.

METHODS

In vitro, PMVEC were transfected with mitogen-activated protein kinase kinase 6 (Glu), which constitutively activates p38, and then stimulated with TNF-α. Flow cytometry and western blotting were performed to detect the cell apoptosis and inflammatory cytokine levels, respectively. In vivo, SAP-ALI was induced by 5% sodium taurocholate and three different doses of SB203580 (2.5, 5.0 or 10.0 mg/kg) were intraperitoneally injected prior to SAP induction. SAP-ALI was assessed by performing pulmonary histopathology assays, measuring myeloperoxidase activity, conducting arterial blood gas analyses and measuring TNF-α, interleukin (IL)-1β and IL-6 levels. Lung microvascular permeability was measured by determining bronchoalveolar lavage fluid protein concentration, Evans blue extravasation and ultrastructural changes in PMVECs. The apoptotic death of pulmonary cells was confirmed by performing a terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling analysis and examining the Bcl2, Bax, Bim and cle-caspase3 levels. The proteins levels of P-p38, NFκB, IκB, P-signal transducer and activator of transcription-3, nuclear factor erythroid 2-related factor 2, HO-1 and Myd88 were detected in the lungs to further evaluate the potential mechanism underlying the protective effect of SB203580.

RESULTS

In vitro, mitogen-activated protein kinase (Glu) transfection resulted in higher apoptotic rates and cytokine (IL-1β and IL-6) levels in TNF-α-treated PMVECs. In vivo, SB2035080 attenuated lung histopathological injury, decreased inflammatory activity (TNF-α, IL-1β, IL-6 and myeloperoxidase) and preserved pulmonary function. Furthermore, SB203580 significantly reversed changes in the bronchoalveolar lavage fluid protein concentration, Evans blue accumulation, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling-positive cell numbers, apoptosis-related proteins (cle-caspase3, Bim and Bax) and endothelial microstructure. Moreover, SB203580 significantly reduced the pulmonary P-p38, NFκB, P-signal transducer and activator of transcription-3 and Myd88 levels but increased the IκB and HO-1 levels.

CONCLUSION

p38 inhibition may protect against SAP-ALI by alleviating inflammation and the apoptotic death of PMVECs.

Therapeutic effects of pentoxifylline on invasive pulmonary aspergillosis in immunosuppressed mice

Background

The most common and severe infection of Aspergillus fumigatus is invasive pulmonary aspergillosis (IPA), which is usually seen in immunocompromised patients. Neutropenia is the primary risk factor implicated in IPA; however, IPA also occurs in patients without neutropenia, namely, those who are immunosuppressed owing to long-term corticosteroid use. With IPA-associated mortality as high as 51–79%, novel and effective treatment strategies are urgently needed. Pentoxifylline (PTX) has been shown to competitively inhibit the family 18 chitinases in fungi, which may be an new antifungal therapy. Hence, the aim of our study was to compare neutropenic and non-neutropenic IPA mouse models, and to evaluate the effect of PTX on IPA in immunosuppressed mice.

Methods

C57BL/6J mice were pre-treated with cyclophosphamide and hydrocortisone. Neutropenic model IPA mice (CTX-IPA) and non-neutropenic IPA mice (HC-IPA) were established by intranasal administration of Aspergillus fumigatus spore suspension. A subset of each group was injected with PTX post-infection. Among these groups, we compared overall survival, pulmonary fungal burden, lung hispathology, and myeloperoxidase (MPO), interleukin 8 (IL-8), and mammalian chitinase concentration in the bronchoalveolar lavage fluid (BALF).

Results

The survival rate of the HC-IPA group was higher than that of the CTX-IPA group, and pulmonary fungal burden was also lower (p < 0.05). The CTX-IPA group showed infiltration of alveolae and blood vessels by numerous hyphae of A. fumigatus. The HC-IPA group exhibited destruction of bronchi, expansion of alveolar septa, increased macrophages aggregation, significant neutrophil infiltration and a few hyphae in peribronchial areas. After PTX treatment, improvement was observed in survival duration and pulmonary fungal burden in HC-IPA mice. MPO and IL-8 levels were lower in the HC-IPA + PTX group compared to the corresponding levels in the HC-IP group. Chitotriosidase (CHIT1) and Chitinase 3-like 1 (CHI3L1) expression in the HC-IPA group was decreased after PTX treatment (p < 0.05).

Conclusion

PTX was found to exert a therapeutic effect in a non-neutropenic mouse model of IPA, which may lead to the development of novel strategies for IPA treatment.

The Role of Pancreatic Infiltrating Innate Immune Cells in Acute Pancreatitis

Acute pancreatitis (AP) is a leading cause of gastrointestinal-related hospital admissions with significant morbidity and mortality. Although the underlying pathophysiology of AP is rather complex, which greatly limits the treatment options, more and more studies have revealed that infiltrating immune cells play a critical role in the pathogenesis of AP and determine disease severity. Thus, immunomodulatory therapy targeting immune cells and related inflammatory mediators is expected to be a novel treatment modality for AP which may improve the prognosis of patients. Cells of the innate immune system, including macrophages, neutrophils, dendritic cells, and mast cells, represent the majority of infiltrating cells during AP. In this review, an overview of different populations of innate immune cells and their role during AP will be discussed, with a special focus on neutrophils and macrophages.

Experimental Acute Pancreatitis Models: History, Current Status, and Role in Translational Research

Acute pancreatitis is a potentially severe inflammatory disease that may be associated with a substantial morbidity and mortality. Currently there is no specific treatment for the disease, which indicates an ongoing demand for research into its pathogenesis and development of new therapeutic strategies. Due to the unpredictable course of acute pancreatitis and relatively concealed anatomical site in the retro-peritoneum, research on the human pancreas remains challenging. As a result, for over the last 100 years studies on the pathogenesis of this disease have heavily relied on animal models. This review aims to summarize different animal models of acute pancreatitis from the past to present and discuss their main characteristics and applications. It identifies key studies that have enhanced our current understanding of the pathogenesis of acute pancreatitis and highlights the instrumental role of animal models in translational research for developing novel therapies.

Diclofenac Sodium Treatment Ameliorates Extrapancreatic Organ Injuries in a Murine Model of Acute Pancreatitis Induced by Caerulein

Aim

We determined the effects of diclofenac sodium, octreotide, and their combination on extrapancreatic organ injuries in caerulein-induced acute pancreatitis in mice.

Methods

A total of 58 BALB-C male mice (25 g) were divided into seven groups and used to create a caerulein-induced acute pancreatitis model. Diclofenac sodium, octreotide, and their combination were given for treatment of caerulin-induced acute pancreatitis in mice. At the end of the experiment, the lung, liver, kidney, and stomach were removed for histopathologic assessment.

Results

Histopathologic investigation revealed a statistically significant difference between the groups in mean congestion, edema, tubular injury, perirenal fat tissue inflammation, and tubular stasis scores in kidney tissue (P < 0.001, P < 0.001, P < 0.001, P < 0.001, and P = 0.048, respectively); mean congestion, edema, neutrophil inflammation, mononuclear inflammation, and emphysematous change scores in the lung (P < 0.001, P < 0.001, P < 0.001, P = 0.030, and P < 0.001, respectively); mean congestion, edema, and neutrophil inflammation scores in the stomach (P = 0.008, P = 0.014, and P < 0.001, respectively); and mean congestion and hydropic degeneration scores in the liver (P = 0.029 and P = 0.002, respectively).

Conclusion

Diclofenac sodium alone ameliorates lung edema due to caerulin-induced acute pancreatitis.

Potential therapeutic roles of 10-dehydrogingerdione and/or pentoxifylline against calcium deposition in aortic tissues of high dietary cholesterol-fed rabbits

The present study aimed to investigate the inhibitory effects of 10-dehydrogingerdione (10-DHGD) and pentoxifylline (PTX) either individually or in combined form on calcium deposition in high cholesterol diet (HCD)-fed rabbits as compared to atorvastatin (ATOR), and to clarify the underlying mechanisms. Three-months-old male New Zealand white rabbits received either normal chow or HCD for 12 weeks. The latter group was subdivided into five groups and concurrently treated either with vehicle (dyslipidemic control), ATOR, 10-DHGD, PTX or combined 10-DHGD and PTX. Blood samples and aortic tissue were collected for biochemical and histological analyses. HCD-fed rabbits displayed dyslipidemia, inflammation, atherosclerotic lesions, and calcium deposition in aortas as compared to normal group. This was associated with up-regulation of bone morphogenetic protein-2 (BMP-2), wingless-type MMTV integration site family 3A (Wnt3a) mRNA levels and osteopontin expression in their aortic tissue, along with higher serum alkaline phosphatase and osteocalcin levels. Furthermore, a marked decrease in osteoprotegerin, along with a significant increase in receptor activator of NF-κB(RANK) levels, was found in aortic tissue of dyslipidemic rabbits. 10-DHGD and PTX monotherapy significantly modulated the afore-mentioned calcification markers and attenuated aortic calcification to greater extent than ATOR. Combination of 10-DHGD and PTX exerted more anti-calcifying effect than either individual drug. Our findings suggested therapeutic roles of 10-DHGD and PTX against aortic calcium deposition in dyslipidemic rabbits, likely mediated by HDL-raising effect and attenuation of associated inflammation. Combination of 10-DHGD and PTX may represent a promising therapeutic strategy for aortic calcification associated with atherosclerosis.

Pentoxifylline exerts anti-inflammatory effects on cerebral ischemia reperfusion‑induced injury in a rat model via the p38 mitogen-activated protein kinase signaling pathway

Pentoxifylline exhibits complex functions with extensive pharmacological effects and is used therapeutically due to its therapeutic effects and rapid metabolism in the body, with no cumulative effects and few side effects. The present study investigated the effects of pentoxifylline on cerebral ischemia reperfusion‑induced injury (IRI) through suppression of inflammation in rats. Hematoxylin and eosin staining was performed to evaluate the number of neurocytes, and ELISAs were applied to measure tumor necrosis factor‑α, interleukin‑6, malondialdehyde and superoxide dismutase activities. Treatment with pentoxifylline significantly recovered the cerebral ischemia reperfusion‑induced neurological deficit score and cerebral infarct volume in rats. In addition, pentoxifylline treatment significantly reversed the cerebral ischemia reperfusion‑induced interleukin‑6, tumor necrosis factor‑α, malondialdehyde and superoxide dismutase levels in vivo. Furthermore, pentoxifylline significantly inhibited cyclooxygenase‑2 and inducible nitric oxide synthase mRNA and protein expression in cerebral IRI mice. Treatment with pentoxifylline also significantly suppressed the expression of cleaved caspase‑3 and p38 mitogen‑activated protein kinase (MAPK) protein in cerebral IRI mice. These results indicate that the protective effects of pentoxifylline on cerebral IRI may occur via the p38 MAPK signaling pathway.

Effect of Previous High Glutamine Infusion on Inflammatory Mediators and Mortality in an Acute Pancreatitis Model

Parenteral glutamine supplementation in acute inflammatory conditions is controversial. We evaluated the inflammatory and survival responses after parenteral glutamine infusion in sodium taurocholate-induced acute pancreatitis (AP) model. Lewis rats received 1 g/kg parenteral glutamine (n = 42), saline (n = 44), or no treatment (n = 45) for 48 h before AP induction. Blood, lung, and liver samples were collected 2, 12, and 24 h after AP to measure serum cytokines levels and tissue heat shock protein (HSP) expression. From each group, 20 animals were not sacrificed after AP for a 7-day mortality study. Serum cytokine levels did not differ among groups at any time point, but the intragroup analysis over time showed higher interferon-γ only in the nontreatment and saline groups at 2 h (versus 12 and 24 h; both p ≤ 0.05). The glutamine group exhibited greater lung and liver HSP90 expression than did the nontreatment group at 2 and 12 h, respectively; greater liver HSP90 and HSP70 expression than did the saline group at 12 h; and smaller lung HSP70 and liver HSP90 expression than did the nontreatment group at 24 h (all p ≤ 0.019). The 7-day mortality rate did not differ among groups. In experimental AP, pretreatment with parenteral glutamine was safe and improved early inflammatory mediator profiles without affecting mortality.

Pentoxifylline decreases serum level of adhesion molecules in atherosclerosis patients

BACKGROUND

Inflammation is involved in development, progression, and complications of atherosclerotic disease. Clinical studies have indicated that the level of monocyte chemoattractant protein 1 (MCP-1), IL-18, and adhesion molecules correlates with the severity of atherosclerosis and can predict future cardiovascular events. Experimental studies have shown pentoxifylline (PTX) reduces these factors in animal models. The purpose of the present pilot study was to evaluate effect of PTX on a group of inflammatory biomarkers in patients with coronary artery disease (CAD).

METHODS

Forty patients with angiographically documented CAD, who fulfilled inclusion and exclusion criteria, were entered in the double-blind, randomized, pilot clinical study. The patients were randomly given PTX (400 mg three times daily) or placebo (3 tab/day) for 2 months. Serum concentrations of MCP-1, IL-18, intercellular adhesion Molecule 1 (ICAM-1), and vascular cell adhesion molecule 1 (VCAM-1) were measured before and at the end of intervention by enzyme-linked immunosorbant assay.

RESULTS

Our study showed that the serum levels of ICAM-1 and VCAM-1 was decreased in the study population after two-month treatment (P<0.05).

CONCLUSION

Based on the results of our pilot study, administration of PTX in CAD patients significantly decreases adhesion molecules levels.

Pentoxifylline attenuates nitrogen mustard-induced acute lung injury, oxidative stress and inflammation

Nitrogen mustard (NM) is a toxic alkylating agent that causes damage to the respiratory tract. Evidence suggests that macrophages and inflammatory mediators including tumor necrosis factor (TNF)α contribute to pulmonary injury. Pentoxifylline is a TNFα inhibitor known to suppress inflammation. In these studies, we analyzed the ability of pentoxifylline to mitigate NM-induced lung injury and inflammation. Exposure of male Wistar rats (150-174 g; 8-10 weeks) to NM (0.125 mg/kg, i.t.) resulted in severe histopathological changes in the lung within 3d of exposure, along with increases in bronchoalveolar lavage (BAL) cell number and protein, indicating inflammation and alveolar-epithelial barrier dysfunction. This was associated with increases in oxidative stress proteins including lipocalin (Lcn)2 and heme oxygenase (HO)-1 in the lung, along with pro-inflammatory/cytotoxic (COX-2(+) and MMP-9(+)), and anti-inflammatory/wound repair (CD163+ and Gal-3(+)) macrophages. Treatment of rats with pentoxifylline (46.7 mg/kg, i.p.) daily for 3d beginning 15 min after NM significantly reduced NM-induced lung injury, inflammation, and oxidative stress, as measured histologically and by decreases in BAL cell and protein content, and levels of HO-1 and Lcn2. Macrophages expressing COX-2 and MMP-9 also decreased after pentoxifylline, while CD163+ and Gal-3(+) macrophages increased. This was correlated with persistent upregulation of markers of wound repair including pro-surfactant protein-C and proliferating nuclear cell antigen by Type II cells. NM-induced lung injury and inflammation were associated with alterations in the elastic properties of the lung, however these were largely unaltered by pentoxifylline. These data suggest that pentoxifylline may be useful in treating acute lung injury, inflammation and oxidative stress induced by vesicants.

Protective effects of pentoxifylline in pulmonary inflammation are adenosine receptor A2A dependent

Pentoxifylline (PTX) has been shown to exert anti-inflammatory effects in experimental acute lung injury. However, results in humans were controversial. Recent in vitro studies suggested that the adenosine receptor A2A may be required for PTX to be effective. Therefore, we studied the association between A2A and PTX in a murine model of LPS-induced pulmonary inflammation. PTX treatment (10 mg/kg) reduced cellular influx (by 40%), microvascular permeability (30%), and the release of chemotactic cytokines into the alveolar space (TNF-α 60%, IL-6 60%, and CXCL2/3 53%, respectively). These protective effects were abolished completely in A2A(-/-) mice and in wild-type mice that had been treated with the selective A2A antagonist (1 mg/kg), but effects were not different in mice with altered adenosine levels. In vitro transmigration assays revealed a pivotal role of the endothelium in PTX-mediated PMN migration, with a reduction of 50% (2 mM PTX). This effect was also A2A dependent. Further, oxidative burst of human PMNs was A2A-dependently reduced by 53% after PTX treatment. In summary, PTX exhibits its anti-inflammatory effects in LPS-induced lung injury through an A2A-dependent pathway. These results will help to better understand previous conflicting data on PTX in inflammation and will direct further studies to consider the predominant role of A2A.

Is there a therapeutic window for pentoxifylline after the onset of acute pancreatitis?

PURPOSE

To investigate the effects of pentoxifylline (PTX) in experimental acute pancreatitis (AP) starting drug administration after the induction of the disease.

METHODS

One hundred male Wistar rats were submitted to taurocholate-induced AP and divided into three groups: Group Sham: sham-operated rats, Group Saline: AP plus saline solution, and Group PTX: AP plus PTX. Saline solution and PTX were administered 1 hour after induction of AP. At 3 hours after AP induction, peritoneal levels of tumor necrosis factor (TNF)-α, and serum levels of interleukin (IL)-6 and IL-10 levels were assayed by Enzyme-Linked Immunosorbent Assay (ELISA). Determinations of lung myeloperoxidase activity (MPO), histological analysis of lung and pancreas, and mortality study were performed.

RESULTS

PTX administration 1 hour after induction of AP caused a significant decrease in peritoneal levels of TNF-α and in serum levels of IL-6 and IL-10 when compared to the saline group. There were no differences in lung MPO activity between the two groups with AP. A decrease in mortality was observed in the PTX treatment compared to the saline group.

CONCLUSIONS

Administration of PTX after the onset of AP decreased the systemic levels of proinflammatory cytokines, raising the possibility that there is an early therapeutic window for PTX after the initiation of AP.

Effect of Pentoxifylline Administration on Mast Cell Numbers and Degranulation in a Diabetic and Normoglycemic rat Model Wound Healing

BACKGROUND

Wound healing is a complicated and integrated process. Researches in the molecular level on human and animal models have indicated several molecular changes related to the effect of diabetes on wound healing process.

OBJECTIVES

Increasing number of researches implicates the influence of mast cells on skin wound repairing. In this study the effect of systemic pentoxifylline (PTX) administration (daily dose of 25mg/kg twice a day, for 7 consecutive days) on normoglycemic (NG) and diabetic (DB) wistar rat's wound healing by secondary intention was studied.

MATERIALS AND METHODS

In this study forty eight wistar rats (weighting 250-350g) were divided randomly in two groups: Normoglycemic and diabetic, each group was divided into experimental and control groups, experimental received intraperitoneal (PTX) and controls received distilled water (DW). The number and maturing process of mast cells was evaluated by counting the number of types of mast cells [1][2][3] microscopically and by stereological methods on day 3 and 7 after surgery.

RESULTS

In this study it was cleared that in wound healing process PTX caused increasing the number of type 2 mast cells in all experimental groups(P = 0.00). In normoglycemic experimental group, receiving PTX there was decrease in the number of type3 mast cells, comparing experimental NG groups (P = 0.00).

CONCLUSIONS

In all PTX treated groups delay in converting type 2 into type 3 mast cell was seen. Pentoxifylline causes decreasing mast cell degranulation in wound healing process.

Pretreatment with pentoxifylline attenuates lung injury induced by intestinal ischemia/reperfusion in rats

PURPOSE

To investigate the protective effect of pentoxifylline against the lung injury observed after intestinal ischemia (I) followed by a period of reperfusion (R).

METHODS

Twenty-eight male Wistar rats were equally divided into 4 experimental groups and operated under ketamine-xylazine anesthesia. (1) Sham: falsely-operated animals; (2) SS+IR: intestinal ischemia was accomplished by clipping the superior mesenteric artery during 60 minutes, with an administration of a standard volume of saline solution (SS) 5 min before the end of the ischemia period; the clip was then releases or a 120-min period of reperfusion; (3) I+PTX+R: ischemia as above, PTX was administered (25 mg/kg) and the gut reperfused as above; (4) PTX+I+PTX+R: Five minutes before arterial occlusion PTX was administered; the superior mesenteric artery was then clipped for 60 minutes. After 55-min ischemia, an additional dosis of PTX was administered; the clip was removed for reperfusion as above. At the 60th min of reperfusion a third dosis of PTX was administered.

RESULTS

PTX markedly attenuated lung injury as manifested by significant decreases (all P<0.001 as compared with the SS+IR group) of pulmonary wet/dry tissue weight ratio, total protein content, myeloperoxidase activity and tumor necrosis factor-alpha. Moreover, it was apparent that in the group PTX+I+PTX+R the improvements have been even more significant.

CONCLUSION

PTX exerted a protective effect on the lung from the injuries caused by intestinal ischemia/reperfusion.

Review of experimental animal models of biliary acute pancreatitis and recent advances in basic research

Acute pancreatitis (AP) is a formidable disease, which, in severe forms, causes significant mortality. Biliary AP, or gallstone obstruction-associated AP, accounts for 30-50% of all clinical cases of AP. In biliary AP, pancreatic acinar cell (PAC) death (the initiating event in the disease) is believed to occur as acinar cells make contact with bile salts when bile refluxes into the pancreatic duct. Recent advances have unveiled an important receptor responsible for the major function of bile acids on acinar cells, namely, the cell surface G-protein-coupled bile acid receptor-1 (Gpbar1), located in the apical pole of the PAC. High concentrations of bile acids induce cytosolic Ca(2+) overload and inhibit mitochondrial adenosine triphosphate (ATP) production, resulting in cell injury to both PACs and pancreatic ductal epithelial cells. Various bile salts are employed to induce experimental AP, most commonly sodium taurocholate. Recent characterization of taurolithocholic acid 3-sulphate on PACs has led researchers to focus on this bile salt because of its potency in causing acinar cell injury at relatively low, sub-detergent concentrations, which strongly implicates action via the receptor Gpbar1. Improved surgical techniques have enabled the infusion of bile salts into the pancreatic duct to induce experimental biliary AP in mice, which allows the use of these transgenic animals as powerful tools. This review summarizes recent findings using transgenic mice in experimental biliary AP.

Vasoactive intestinal peptide promotes gut barrier function against severe acute pancreatitis

To explore the influence of vasoactive intestinal peptide (VIP) on the gut barrier function in severe acute pancreatitis (SAP). Fifty four SD rats were randomly divided into three groups: sham operated (SO) group, SAP group and VIP intervention group. Each group was further divided into three time points: 1, 6 and 12 h after operation with 6 rats for each treatment point. SAP models were induced by retrograde injection of 4% sodium taurocholate into the bili-pancreatic duct. VIP intervention group was made by 5 nmol VIP intraperitoneal injection within 5 min after SAP model successfully obtained. The VIP in plasma and intestinal homogenate were detected with ELISA. The endotoxin in plasma of all groups was also tested. The expression levels of TLR4, TNF-α, IL-6, and IL-10 in gut mucosa were measured by RT-PCR. Meanwhile intestinal samples were harvested for pathological examination. Compared to SO group, the VIP in plasma and intestinal homogenate of SAP group were significantly decreased at 1 h after induction, and then gradually increased to beyond the level of SO group at 12 h. The endotoxin of SAP group was continually increased. The mRNA levels of TLR4, TNF-α, IL-6, and IL-10 were also increased with obvious pathological injuries in the intestine. In the VIP group, endotoxin in plasma was obviously decreased compared to SAP group. The expressions of TNF-α, IL-6 mRNA were suppressed while IL-10mRNA was increased. The intestinal pathological injuries were also markedly alleviated. These results suggested that VIP had protective effects on SAP gut barrier function through inhibiting intestinal mucosal inflammatory responses.

Oral melatonin attenuates lung inflammation and airway hyperreactivity induced by inhalation of aerosolized pancreatic fluid in rats

Melatonin is a free radical scavenger with potent antioxidant properties and immunomodulatory effects. The purpose of this study was to determine the effects of orally administered melatonin in a pancreatic fluid (PF)-induced lung inflammation and airway hyperreactivity model. Aerosolized PF was introduced into airways to induce inflammation in rats. Animals were randomized into three experimental groups: sham treated; PF treated (200 μL/kg); and PF with melatonin (10 mg/kg) pretreatment. Airway reactivity to methacholine, airflow and airway resistance, bronchoalveolar lavage (BAL) cellular differential, the tumor necrosis factor α (TNFα) level, lavage nitric oxide, hydroxyl radical, and lactic dehydrogenase (LDH) were compared among groups. mRNA expressions of inducible nitric oxide synthase (iNOS) and TNFα in lung tissues were determined by real-time polymerase chain reaction. Protein expressions of iNOS and nitrotyrosine and lung tissue myeloperoxidase (MPO) activity were determined using an ELISA assay. Oral melatonin treatment indicated anti-inflammatory efficacy as evidenced by decreased methacholine sensitivity by 24% and airway obstruction by 28%, reduction in BAL eosinophil (P < 0.01) and neutrophil counts (P < 0.05), LDH (P < 0.05), and TNFα concentrations (P < 0.05) when compared to levels in sham-treated rats. Melatonin-treated animals also had reduced nitric oxide and hydroxyl radical concentrations (P < 0.05) in lavage fluid. Oral melatonin significantly reduced mRNA and protein expression of iNOS (P < 0.05 and P < 0.01, respectively), TNFα (P < 0.05), nitrotyrosine (P < 0.05), and MPO activity (P < 0.05) in lung tissues when compared with the sham-treated animals. These results suggest that oral treatment with melatonin had a beneficial effect on PF-induced obstructive ventilatory insufficiency by attenuating nitrosative and oxidative stress.

Anti-inflammatory effects and possible mechanism of action of lupeol acetate isolated from Himatanthus drasticus (Mart.) Plumel

BACKGROUND

The species Himatanthus drasticus is popularly known in Northeast Brazil as "janaguba" and belongs to the family Apocynaceae. The latex collected from its stem bark is used for several purposes including anti-inflammatory properties and presents among its bioactive constituents the pentacyclic triterpene lupeol. The objective of the present work was to study in vivo and in vitro the lupeol acetate (LA) isolated from the plant latex, in several models of inflammation.

METHODS

Male Swiss mice (25-30 g, 6-24 animals per group) were administered with LA, 30 min before the test initiation. In the evaluation of analgesic activity the formalin test was used. The anti-inflammatory activity was evaluated by the following tests: paw edema induced by carrageenan and dextran, and the carrageenan-induced neutrophil migration into peritoneal cavities. Furthermore, the effect of LA on the myeloperoxidase release (MPO, an inflammation biomarker) from human neutrophils was also determined, as well as its antioxidant potential by the DPPH assay.

RESULTS

In the formalin test, LA (10, 25 and 50 mg/kg, i.p.) inhibited both the 1st (neurogenic, 0-5 min) and mainly the 2nd (inflammatory, 20-25 min) phase. Naloxone completely reversed the LA effect, indicating the participation of the opioid system. LA also significantly inhibited carrageenan- and dextran-induced paw edemas, as well as the neutrophil migration to the peritoneal cavity evaluated by the carrageenan-induced pleurisia. In this model, the effect of a very low dose of LA (0.1 mg/kg) was potentiated by the same dose of pentoxifylline (PTX), a known TNF-alpha inhibitor. LA (25 and 50 μg/ml) was also very effective in inhibiting MPO released from stimulated human neutrophils, and significantly decreased the number of cells expressing iNOS activity in the paw of mice submitted to carrageenan-induced edema, suggesting a drug involvement with the NO system.

CONCLUSIONS

The anti-inflammatory effect of LA probably involves the opioid system, as indicated by the complete blockade of the opioid antagonist naloxone. Furthermore, the LA effect was potentiated by PTX (a TNF-alpha inhibitor). LA also decreased the number of iNOS cells, suggesting the participation of pro-inflammatory cytokines and the NO system in the drug action.

Curcumin attenuates airway hyperreactivity induced by ischemia-reperfusion of the pancreas in rats

OBJECTIVES

Ischemia-reperfusion (I/R) of the rat pancreas induces acute pancreatitis with a systemic inflammatory response. Activated inflammatory cells are sequestered in the lung, and the consequent respiratory burst may increase airway reactivity. In this study, we characterized the effect of the antioxidant curcumin on airway hyperreactivity induced by pancreatic I/R.

METHODS

Ischemia of the pancreas was induced by clamping the gastroduodenal and the splenic artery for 2 hours followed by reperfusion for 6 hours. The pulmonary function data of Penh, a measurement of airway resistance, were used to show the airway responses to a methacholine challenge. The blood concentration of oxygen radicals, nitric oxide, and tumor necrosis factor-alpha (TNFalpha) were measured after pancreatic I/R. mRNA expressions of inducible nitric oxide synthase (iNOS) and TNFalpha in lung tissues were measured after pancreatic I/R. Pretreatment with curcumin (20 mg/kg) was administered by intraperitoneal injection 2 hours before pancreatic I/R.

RESULTS

The protocol resulted in significant elevations of the blood concentrations of amylase, hydroxyl radical, nitric oxide, TNFalpha, and white cells among the I/R group. iNOS and TNFalpha mRNA expressions also significantly increased in lung tissues. Pulmonary function data showed that pancreatic I/R induced significant increases in responses to methacholine challenge: Penh increased significantly in the I/R group when compared with the sham group. Pretreatment with curcumin significantly attenuated the inflammatory, oxidative, and nitrosative responses and lung tissue iNOS and TNFalpha expressions. Curcumin also attenuated airway reactivity to methacholine challenge.

CONCLUSIONS

I/R of the pancreas induced systemic inflammatory responses with respiratory burst, nitrosative stress, and hyperresponses in the airways. Curcumin, which has antioxidant and anti-inflammatory effects, significantly attenuated the inflammatory responses and airway hyperreactivity induced by pancreatic I/R.

Pentoxifylline modulates p47phox activation and downregulates neutrophil oxidative burst through PKA-dependent and -independent mechanisms

BACKGROUND AND AIM

Pentoxifylline (PTX) has been proven to be an inhibitor of fMLP-induced neutrophil (PMN) oxidative burst and is thought to function by increasing cAMP and Protein kinase A (PKA). We hypothesized that PTX diminishes production of the neutrophil respiratory burst by both PKA-dependent and independent mechanisms.

MATERIAL AND METHODS

Human neutrophils were isolated and stimulated with fMLP (1microM) alone or in combination with PTX (2mM). PMN activation was determined by the cytochrome C reduction method in the presence and absence of p38 MAPK (SB203580), ERK (PD98059), and PKA inhibitors (H89). Western blot analysis of Ras, Raf, p38 MAPK, ERK, and Akt was performed in PMNs exposed to fMLP and PTX. Cell membranes were fractionated to measure membrane-associated p47 phox. Treated cells were imaged using confocal microscopy to examine changes in localization of Akt and p47phox.

RESULTS

PTX produced a decrease in oxidative burst that was diminished but not abrogated by H89 exposure. The reduction in Ras, Raf, and Akt activation seen with PTX was not effected by the presence of H89. The ability of PTX to attenuate phosphorylation of p38 MAPK and ERK was significantly decreased in the presence of H89, suggesting a PKA-dependent mechanisms. Membrane fractions of neutrophils demonstrate that PTX decreased membrane-associated p47phox, thus diminishing the ability to generate oxidative burst. PTX also decreased membrane localization of Akt and p47phox by confocal microscopy.

CONCLUSIONS

PTX attenuates activation of signaling molecules involved in activation of p47phox and suppress the subsequent assembly of the NADPH machinery through both PKA-dependent and PKA-independent mechanisms.

Effects of pentoxifylline on inflammation and lung dysfunction in ventilated septic animals

Acute respiratory distress syndrome secondary to sepsis is associated with high morbidity and mortality. The purpose of this study was to characterize the effects of ventilatory strategy and the modulating activity of pentoxifylline in a sepsis-induced lung dysfunction model. Male Wistar rats were randomly divided into six groups, undergoing two different ventilatory strategies. Rats received live Escherichia coli or saline intraperitoneally. After 6 hours, the septic animals were treated with either pentoxifylline (25 mg/kg for 20 minutes) or normal saline infusion and ventilated with low tidal volume (6 mL/kg; septic animals with E. coli intraperitoneal [IP] infusion, PTX-treated and ventilated with low tidal volume and septic animals with E. coli IP infusion and ventilated with low tidal volume, respectively) or high tidal volume (12 mL/kg; septic animals with E. coli IP infusion, PTX-treated and ventilated with high tidal volume and septic animals with E. coli IP infusion and ventilated with high tidal volume, respectively) for 3 hours. The control animals received normal saline infusion and, after 6 hours, were ventilated with low or high tidal volume (control animals with saline infusion and ventilated with low tidal volume and control animals with saline infusion and ventilated with high tidal volume, respectively). Lung dysfunctions were assessed by wet-to-dry lung ratios, total cell count, total protein, malondialdehyde, and tumor necrosis factor-alpha concentrations in bronchoalveolar lavage (BAL). Septic animals with E. coli IP infusion and ventilated with high tidal volume presented increased wet-to-dry lung ratios, total cell count, total protein, and malondialdehyde in BAL compared with the septic animals ventilated with low tidal volume. Septic animals treated with pentoxifylline presented higher arterial oxygenation and lower cellular influx, protein leakage, malondialdehyde concentration, and tumor necrosis factor-alpha levels in BAL compared with septic animals undergoing the same ventilatory support strategies (septic animals with E. coli IP infusion and ventilated with low tidal volume and septic animals with E. coli IP infusion and ventilated with high tidal volume). Ventilatory strategy modulated the inflammatory response and pulmonary alterations in a sepsis-induced acute lung injury model, and these effects are improved by pentoxifylline.

[Anti-inflammatory effects of pentoxifylline: importance in cardiac surgery]

Initially introduced as a rheologic agent for use in intermittent claudication due to peripheral artery disease and in ischemic cerebrovascular disease, the methylxanthine derivative pentoxifylline (PTX) has been shown to possess several anti-inflammatory properties which make this drug an interesting immunomodulating adjunct for the management of patients undergoing cardiac surgery. As an unspecific phosphodiesterase inhibitor PTX ameliorates the inflammatory response following a septic stimulus and blunts organ dysfunction after ischemia-reperfusion injury. Apart from this several small clinical studies have shown that the use of PTX may blunt the inflammatory response induced by cardiac surgery using a cardiopulmonary bypass. Additionally it has been shown that the perioperative application of this drug may improve postoperative function of organs at risk, such as the kidneys and liver.

Ghrelin attenuates acute pancreatitis-induced lung injury and inhibits substance P expression

OBJECTIVE

To investigate the effect of ghrelin administration on the severity of acute lung injury and on the production of proinflammatory cytokines and Substance P (SP) in rats with acute pancreatitis (AP).

METHODS

AP was induced in rats by sodium taurocholate injection through pancreaticobiliary duct. Ghrelin 20 nmol/kg was given before and after the treatment. Tumor necrosis factor-alpha, interleukin-1beta, and -6 levels in the serum were measured using the radioimmunoassay method. Morphological signs of lung injury, pulmonary water content, microvascular permeability, and myeloperoxidase activity were measured. Meanwhile, the determination of pulmonary SP mRNA level and its expression were performed by reverse transcriptase polymerase chain reaction and immunohistochemistry.

RESULTS

The serum proinflammatory cytokines, pulmonary water content, microvascular permeability, and myeloperoxidase activity were increased, and morphological damages were observed in the lung of AP rats. SP mRNA level and its expression were significantly higher in sham-operated rats (P < 0.05). Morphological damages were attenuated and serum cytokines and pulmonary parameters were reduced by pre- and posttreatment with ghrelin. Pulmonary SP expression was also significantly down-regulated by ghrelin (P < 0.05).

CONCLUSIONS

Ghrelin attenuates the severity of acute lung injury induced by AP. The reduction of neutrophil sequestration, limitation of proinflammatory cytokines release, and inhibition of pulmonary SP expression may be the mechanisms involved in the therapeutic effect of ghrelin.

Burns, inflammation, and intestinal injury: protective effects of an anti-inflammatory resuscitation strategy

BACKGROUND

Intestinal barrier breakdown after severe burn can lead to intestinal inflammation, which may act as the source of the systemic inflammatory response. In vitro intestinal cell studies have shown that mitogen-activated protein kinase (MAPK) signaling is an important modulator of intestinal inflammation. We have previously observed that pentoxifylline (PTX) attenuates burn-induced intestinal permeability and tight junction breakdown. We hypothesized that PTX would limit intestinal barrier breakdown and attenuate inflammatory signaling via the MAPK pathway.

METHODS

Male balb/c mice underwent 30% total body surface area full-thickness steam burn. Immediately after burn, animals received an intraperitoneal injection of PTX (12.5 mg/kg) in normal saline or normal saline alone. In vivo intestinal permeability to 4 kDa fluorescein isothiocyanate-dextran was measured. Intestinal extracts were obtained to measure interleukin-6 by enzyme-linked immunosorbent assay, and phosphorylated p38 MAPK, p38 MAPK, phosphorylated extracellular signal-related kinase (1/2) (ERK (1/2)), and ERK (1/2) by immunoblotting. Acute lung injury was assessed by histology at 24 hours after burn.

RESULTS

Administration of PTX immediately after injury attenuated burn-induced intestinal permeability. PTX also decreased the burn-induced phosphorylation of p38 MAPK and decreased phosphorylation of ERK (1/2) at 2 hours and 24 hours after injury. Animals given PTX had decreased intestinal interleukin-6 levels. A single dose of PTX also decreased histologic lung injury at 24 hours after burn.

CONCLUSION

PTX attenuates burn-induced intestinal permeability and subsequent intestinal inflammation. Use of PTX after burn was also associated with decreased acute lung injury. Because of its compelling anti-inflammatory effects, PTX may be an ideal candidate for use as an immunomodulatory adjunct to resuscitation fluid.

Pentoxifylline prevents loss of PP2A phosphatase activity and recruitment of histone acetyltransferases to proinflammatory genes in acute pancreatitis

Mitogen-activated protein kinases (MAPKs) are considered major signal transducers early during the development of acute pancreatitis. Pentoxifylline is a phosphodiesterase inhibitor with marked anti-inflammatory properties through blockade of extracellular signal regulated kinase (ERK) phosphorylation and tumor necrosis factor alpha production. Our aim was to elucidate the mechanism of action of pentoxifylline as an anti-inflammatory agent in acute pancreatitis. Necrotizing pancreatitis induced by taurocholate in rats and taurocholate-treated AR42J acinar cells were studied. Phosphorylation of ERK and ERK kinase (MEK1/2), as well as PP2A, PP2B, and PP2C serine/threonine phosphatase activities, up-regulation of proinflammatory genes (by reverse transcription-polymerase chain reaction and chromatin immunoprecipitation), and recruitment of transcription factors and histone acetyltransferases/deacetylases to promoters of proinflammatory genes (egr-1, atf-3, inos, icam, il-6, and tnf-alpha) were determined in the pancreas during pancreatitis. Pentoxifylline did not reduce MEK1/2 phosphorylation but prevented the marked loss of serine/threonine phosphatase PP2A activity induced by taurocholate in vivo without affecting PP2B and PP2C activities. The rapid loss in PP2A activity induced by taurocholate in acinar cells was due to a decrease in cAMP levels that was prevented by pentoxifylline. Pentoxifylline also reduced the induction of early (egr-1, atf-3) responsive genes and abrogated the up-regulation of late (inos, icam, il-6, tnf-alpha) responsive genes and recruitment of transcription factors (nuclear factor kappaB and C/EBPbeta) and histone acetyltransferases to their gene promoters during pancreatitis. In conclusion, the beneficial effects of pentoxifylline--and presumably of other phosphodiesterase inhibitors--in this disease seem to be mediated by abrogating the loss of cAMP levels and PP2A activity as well as chromatin-modifying complexes very early during acute pancreatitis.

Effect of pioglitazone on expression of intercellular adhesion molecule-1 in pulmonary tissues of rats with severe acute pancreatitis

AIM: To investigate the expression changes of pulmonary intercellular adhesion molecule-1 (ICAM-1) after pioglitazone treatment in rats with severe acute pancreatitis (SAP).

METHODS: A total of 54 Sprague Dawley rats were randomly and divided into 3 groups, named group A, C and T (n = 18). Group A and C served as SAP model group and sham operation group, respectively. Rats in group T were treated with pioglitazone, an agonist of peroxisome proliferator activated receptor. The modified Li Qing-hua's method was used to reproduce SAP models. Histopathological changes of pulmonary tissues were examined by microscopy. The activity of myeloperoxidase (MPO) in pulmonary tissues was measured. The expression of pulmonary ICAM-1 was determined by immunohistochemical staining (ABC).

RESULTS: The histological examination revealed intensive inflammatory response in pulmonary tissues after SAP model was induced, but inflammatory response was significantly alleviated in group T. The activity of MPO (6 h: 5.12 ± 0.71 vs 6.03 ± 0.63, P < 0.05; 12 h: 5.20 ± 0.66 vs 8.05 ± 0.62, P < 0.01) in the lung tissues were significantly decreased. After modeling, the expression of ICAM-1 was persistently increased from the 3^rd hour on. In group A, the expression of ICAM-1 was 0.82 ± 0.23, 1.03 ± 0.31 and 1.40 ± 0.58 at the 3^rd, 6^th, and 12^th hour, respectively, and there was significant difference between those at the 12th and 3rd hour (P < 0.05). In group T, ICAM-1 expression was 0.62 ± 0.18, 0.75 ± 0.27 and 0.78 ± 0.31 at the 3^rd, 6^th, and 12th hour, respectively, and there was marked difference at the 12th hour between group A and group T (P < 0.05). ICAM-1 expression was weakly positive in group C, and faded away as time went by.

CONCLUSION: The severity of pancreatitis and degree of lung injury could be predicted by detection of ICAM-1 expression and pioglitazone inhibits the expression of ICAM-1 in SAP.

Effects of gut barrier dysfunction and NF-kappaB activation on aggravating mechanism of severe acute pancreatitis

OBJECTIVE

To study the effects of gut-derived endotoxin translocation and NF-kappaB activation on the aggravating mechanism of severe acute pancreatitis (SAP) and of treatment with pyrrolidine dithiocarbamate (PDTC) on rats with SAP.

METHODS

SD rats were randomly divided into sham operation group (SO), SAP group, SAP + lipopolysaccharide(LPS) group, pyrrolidine dithiocarbamate (PDTC) treatment group and LPS group. Biochemical parameters and cytokines were examined in the serum. Multiple organs pathological slices were examined. Expression of NF-kappaB mRNA in the liver tissue was detected by RT-PCR. Activation of NF-kappaB by the method of streptomycin avidin-peroxidase (SP) and expression of NF-kappaB p65 protein and its binding activity were analyzed by Western blot and electrophoretic mobidity shift assay (EMSA).

RESULTS

Compared with sham operation group, the concentration of TNF-alpha, alanine aminotransferase (ALT), and diamine oxidase (DAO) in serum significantly increased in SAP + LPS group (P < 0.05). Pathological changes were markedly observed in tissues and the expression of NF-kappaB mRNA in the liver significantly increased (P < 0.05) also, the activation of NF-kappaB and binding activity of NF-kappaB p65 protein in the liver markedly increased (P < 0.01) in SAP + LPS group. Treatment with PDTC markedly reduced concentration of ALT, DAO and TNF-alpha, and the expression of NF-kappaB, and the pathologic scores, as well as significantly decreased the expression of NF-kappaB p65 protein.

CONCLUSION

The activation and overexpression of NF-kappaB may participate in the aggravating mechanism of SAP. Treatment with PDTC has a protective effect on multiple organs damage in SAP.