Effects of Phosphodiesterase Inhibition on the Inflammatory Response after Shock: Role of Pentoxifylline

Pentoxifylline in the Treatment of Cutaneous Leishmaniasis: A Randomized Clinical Trial in Colombia

Addition of the immunomodulator pentoxifylline (PTX) to antimonial treatment of mucosal leishmaniasis has shown increased efficacy. This randomized, double-blind, placebo-controlled trial evaluated whether addition of pentoxifylline to meglumine antimoniate (MA) treatment improves therapeutic response in cutaneous leishmaniasis (CL) patients. Seventy-three patients aged 18−65 years, having multiple lesions or a single lesion ≥ 3 cm were randomized to receive: intramuscular MA (20 mg/kg/day × 20 days) plus oral PTX 400 mg thrice daily (intervention arm, n = 36) or MA plus placebo (control arm, n = 37), between 2012 and 2015. Inflammatory gene expression was evaluated by RT-qPCR in peripheral blood mononuclear cells from trial patients, before and after treatment. Intention-to-treat failure rate was 35% for intervention vs. 25% for control (OR: 0.61, 95% CI: 0.21−1.71). Per-protocol failure rate was 32% for PTX, and 24% for placebo (OR: 0.50, 95% CI: 0.13−1.97). No differences in frequency or severity of adverse events were found (PTX = 142 vs. placebo = 140). Expression of inflammatory mediators was unaltered by addition of PTX to MA. However, therapeutic failure was associated with significant overexpression of il1β and ptgs2 (p < 0.05), irrespective of study group. No clinical benefit of addition of PTX to standard treatment was detected in early mild to moderate CL caused by Leishmania (V.) panamensis.

Treatment of endotoxaemia and septicaemia in the equine patient

Endotoxins, constituents of the cell wall of gram-positive and gram-negative bacteria, regularly result in severe illness and death in horses. In endotoxaemia, these constituents are present in the systemic circulation; in septicaemia, whole microbes invade normally sterile parts of the body. Interaction of these endotoxins with pathogen recognition receptors leads to an inflammatory response that cannot always be sufficiently contained and hence needs direct treatment. Over the last decennia, our understanding of the pathophysiology of endotoxaemia and septicaemia has significantly increased. Based on improved understanding of the interaction between receptors and endotoxins as well as the subsequent downstream signalling pathways, new therapeutic targets have been identified in laboratory animal species and humans. Important species differences in the recognition of endotoxins and pathogens by their receptors as well as the inflammatory response to receptor activation hamper extrapolation of this information to the horse (and other species). Historically, horses with endotoxaemia and septicaemia have been treated mainly symptomatically and supportively. Based on the identified therapeutic targets, this review describes the current knowledge of the treatment for endotoxaemia and septicaemia in the horse with reference to the findings in other animal species and humans.

Effects of intravenous administration of pentoxifylline in pancreatic ischaemia-reperfusion injury

BACKGROUND

Therapeutic strategies to reduce the occurrence of pancreatic ischaemia-reperfusion (I-R) injury might improve outcomes in human pancreas and kidney transplantation. In addition to its haemorrheologic effects, pentoxifylline has an anti-inflammatory effect by inhibiting NF-κB activation. This group has previously demonstrated that pentoxifylline induces an anti-inflammatory response in acute pancreatitis and liver I-R models. This led to the hypothesis that pentoxifylline might reduce pancreatic and renal lesions and the systemic inflammatory response in pancreatic I-R injury. The aim of this experimental study was to evaluate the effect of pentoxifylline administration in a rat model of pancreatic I-R injury.

METHODS

Pancreatic I-R was performed in Wistar rats over 1 h by clamping the splenic vessels. The animals submitted to I-R were divided into two groups: Group 1 (n = 20, control) rats received saline solution administered i.v. at 45 min after ischaemia, and Group 2 (n = 20) rats received pentoxifylline (25 mg/kg) administered i.v. at 45 min after ischaemia. Blood samples were collected to enable the determination of amylase, creatinine, tumour necrosis factor-α (TNF-α), interleukin-6 (IL-6) and IL-10. Pancreatic malondialdehyde (MDA) content, pancreas histology and pulmonary myeloperoxidase (MPO) were also assessed.

RESULTS

Significant reductions in serum TNF-α, IL-6 and IL-10 were observed in Group 2 compared with Group 1 (P < 0.05). No differences in pancreatic MDA content or serum amylase levels were observed between the two groups. The histologic score was significantly lower in pentoxifylline-treated animals, denoting less severe pancreatic histologic damage.

CONCLUSIONS

Pentoxifylline administration reduced the systemic inflammatory response, the pancreatic histological lesion and renal dysfunction in pancreatic I-R injury and may be a useful tool in pancreas and kidney transplantation.

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.

Uncovering the neuroenteric-pulmonary axis: vagal nerve stimulation prevents acute lung injury following hemorrhagic shock

AIMS

Trauma/hemorrhagic shock (T/HS) induced gut injury is known to initiate a systemic inflammatory response which can lead to secondary lung injury. We have shown that vagal nerve stimulation (VNS) protects intestinal epithelial integrity after a severe burn insult. We hypothesize that VNS will protect the lung from injury following T/HS by preventing intestinal barrier failure.

MAIN METHODS

Male Balb/c mice were subjected to a T/HS model with and without cervical VNS. Intestinal injury was evaluated by measuring changes in gut barrier function and tight junction protein localization. Lung injury was evaluated using histology and markers of lung inflammation. Using NF-kB-luciferase (NF-kB-luc) transgenic mice, NF-kb-DNA binding was measured by photon emission analysis at 4 after injury.

KEY FINDINGS

T/HS is associated gut injury characterized by histologic injury, increased epithelial permeability, and altered localization of gut tight junction proteins. Cervical VNS prevented the T/HS-induced changes in gut barrier integrity. Gut injury after T/HS was associated with acute lung injury at 24 h characterized by histologic injury, increased number of MPO positive stained cells and MPO enzymatic activity, and increased ICAM-1 expression in lung endothelium. VNS decreased T/HS-induced lung injury with a marked decrease in lung inflammation compared to T/HS alone. Lungs harvested from NF-kB-luc mice at 4h post VNS+T/HS demonstrated decreased DNA binding of NF-kB compared to T/HS alone as measured by changes in bioluminescence.

SIGNIFICANCE

VNS is effective in protecting against acute lung injury caused by hemorrhagic shock through its ability to prevent gut barrier dysfunction.

Use of pentoxifylline in treatment of children with dengue hemorrhagic fever

The current treatment for dengue hemorrhagic fever largely consists of supportive care. The drug pentoxifylline has been shown to blunt the proinflammatory actions of tumor necrosis factor-α, a key mediator of dengue hemorrhagic fever. We performed a pilot study evaluating pentoxifylline's effect on 55 children with dengue hemorrhagic fever. We believe our findings support the existing literature on its potential use in severe infection.

Olprinone and colforsin daropate alleviate septic lung inflammation and apoptosis through CREB-independent activation of the Akt pathway

Olprinone, a specific phosphodiesterase III inhibitor, and corforsin daropate, a direct adenylate cyclase activator, are now being used in critical conditions. We investigated whether their therapeutic use provides protection against septic acute lung injury (ALI) and mortality. Polymicrobial sepsis was induced by cecal ligation and puncture (CLP) in BALB/c mice. Olprinone or colforsin daropate was continuously given through an osmotic pump that was implanted into the peritoneal cavity immediately following CLP. These treatments prevented the ALI development in CLP mice, as indicated by the findings that severe hypoxemia, increased pulmonary vascular permeability, and histological lung damage were strikingly remedied. Furthermore, continued administration of olprinone or colforsin daropate suppressed apoptosis induction in septic lungs and improved the survival of CLP mice. Olprinone and corforsin daropate enhanced Akt phosphorylation in septic lungs. Wortmannin, which inhibits the Akt upstream regulator phosphatidylinositol 3-kinase, abrogated the protective effects of olprinone and corforsin daropate on sepsis-associated lung inflammation and apoptosis. In vivo transfection of cyclic AMP response element binding protein (CREB) decoy oligodeoxynucleotide failed to negate the abilities of these agents to increase Akt phosphorylation and to inhibit IκBα degradation in septic lungs. These results demonstrate for the first time that CREB-independent Akt-mediated signaling is a critical mechanism contributing to the therapeutic effects of olprinone and corforsin daropate on septic ALI. Moreover, our data also suggest that these cyclic AMP-related agents, by blocking both nuclear factor-κB activation and apoptosis induction, may represent an effective therapeutic approach to the treatment of the septic syndrome.

Effects of trauma-hemorrhage and IL-6 deficiency on splenic immune function in a murine trauma model

Splenic immune function is known to be depressed following hemorrhage. The present study investigates the effects of femoral shaft fracture, isolated or in combination with hemorrhage, on early stage cytokine production capacity of splenocytes and observes the role of IL-6 under these conditions. Male IL-6 knockout (IL-6^−/−) and wild-type mice (WT) were randomly divided into three groups: sham (S), isolated femoral fracture (Fx), and femoral fracture + volume controlled hemorrhage (TH-Fx) (n = 6 per group). Animals were sacrificed four hours after induction of hemorrhage and fracture. Cytokine release (TNF-α, IL-6, and IL-10) of isolated and LPS-stimulated splenocytes was determined by cytometric bead array. Femoral fracture with or without hemorrhage caused a suppression of in vitro cytokine production capacity of splenocytes at an early posttraumatic stage in WT and IL-6^−/−. In the absence of IL-6, the profile of splenic cytokine secretion is significantly altered, identifying this cytokine as a potential therapeutic target to modulate the posttraumatic immune response.

Pentoxifylline inhibits hepatic stellate cells proliferation via the Raf/ERK pathway

Pentoxifylline (PTX), which is a xanthine derivative, is a well-known suppressor of tumor necrosis factor-alpha (TNF-alpha) production in inflammatory cells and has also been shown to inhibit collagen synthesis in hepatic stellate cells (HSCs) in vitro. The present study aimed to evaluate the effects of PTX on proliferation in HSCs as mediated by the Raf/MEK/extracellular-signal-regulated kinase (ERK) signaling pathway. The rat hepatic stellate cell line T6 and activated primary rat HSCs were used in this study. The proliferation rate of the cells treated with 1 mM PTX significantly decreased compared with that of the control in T6 cells (78.3 ± 6.03% at 12 h, 61.0 ± 7.55% at 24 h, and 44.7 ± 2.08% at 48 h, p < 0.05). PTX (1 mM) also decreased the fraction of the HSC population in the S and G2/M-phases of the cell cycle in primary activated rat HSCs. The Raf-1 inhibitor GW5074 and the ERK inhibitor U0126 had inhibitory effects that were similar to those of PTX on HSC proliferation. In addition, PTX inhibited the phosphorylation of Raf-1 (p-Raf-1) and ERK (p-ERK) in a dose- and time-dependent manner in HSCs. These data provide evidence that PTX suppresses HSC proliferation via the Raf/MEK/ERK pathway.

The relative efficacy of aminoguanidine and pentoxifylline in modulating endotoxin-induced cardiac stress

This study investigates the effect of aminoguanidine (AG), a selective inducible nitric oxide synthase (iNOS) inhibitor, and pentoxifylline (PTX), a tumour necrosis factor-alpha (TNF-α) inhibitor, on lipopolysaccharide (LPS)-induced cardiac stress. Rats were divided into four groups: group I served as a control, group II (LPS) received a single intraperitoneal injection of LPS (10 mg·kg(-1) ), group III (LPS+AG) and group IV (LPS+PTX) were injected with either AG (100 mg·kg(-1) ) or PTX (150 mg·kg(-1) ) intraperitoneally 10 days prior to LPS administration. Normalization of cardiac levels of nitrite/nitrate (NO(X) ), malondialdehyde (MDA), glutathione (GSH), heme oxygenase-1 (HO-1), glutathione peroxidase (GPx) and Na(+) , K(+) -ATPase activities was evident in the AG group. Both AG and PTX decreased the elevated serum TNF-α levels, the activities of lactate dehydrogenase (LDH), creatine kinase (CK) and cardiac myeloperoxidase (MPO). The levels of adenosine triphosphate (ATP), adenosine diphosphate (ADP) and phosphocreatine (PCr) were enhanced following AG and PTX pretreatments. Calcium (Ca(2+) ) levels were altered, and the histopathological observations supported the described results. Conclusively, the study highlights the cardioprotective potential of AG and PTX with superior results from AG. These findings reveal the relative contribution of nitric oxide and TNF-α to oxidative stress and energy failure during endotoxemia.

Liquid formulation of pentoxifylline is a poorly tolerated treatment for duchenne dystrophy

INTRODUCTION

In this study we performed an open-label, pilot study of an orally administered liquid formulation of immediate-release pentoxifylline (PTX) on patients with Duchenne muscular dystrophy (DMD). Treatment efficacy, safety, and tolerability were assessed.

METHODS

The tolerability and safety of PTX and measures of muscle strength and function were evaluated during 12 months of treatment.

RESULTS

Seventeen boys with DMD, between 4 and 8 years of age, were enrolled at one of five Cooperative International Neuromuscular Research Group (CINRG) centers. Only 9 were able to complete the 12-month PTX treatment phase; the primary reason for discontinuation was adverse events. Intolerable gastrointestinal side effects were experienced by 65% of participants. Two participants had severe leukopenia that resolved with medication withdrawal.

CONCLUSIONS

Open-label treatment with a liquid formulation of immediate-release PTX resulted in a high incidence of adverse events in boys with DMD. Poor tolerability of this PTX formulation precluded adequate assessment of efficacy.

A novel fluid resuscitation strategy modulates pulmonary transcription factor activation in a murine model of hemorrhagic shock

INTRODUCTION

Combining the hemodynamic and immune benefits of hypertonic saline with the anti-inflammatory effects of the phosphodiesterase inhibitor pentoxifylline (HSPTX) as a hemorrhagic shock resuscitation strategy reduces lung injury when compared with the effects of Ringer's lactate (RL). We hypothesized that HSPTX exerts its anti-inflammatory effects by interfering with nuclear factor kappa B/cAMP response element-binding protein (NF-kappaB-CREB) competition for the coactivator CREB-binding protein (CBP) in lung tissue, thus affecting pro-inflammatory mediator production.

METHODS

Male Sprague-Dawley rats underwent 60 minutes of hemorrhagic shock to reach a mean arterial blood pressure of 35 mmHg followed by resuscitation with either RL or HSPTX (7.5% HS + 25 mg/kg PTX). After four hours, lung samples were collected. NF-kappaB activation was assessed by measuring the levels of phosphorylated cytoplasmic inhibitor of kappa B (I-kappaB) and nuclear NF-kappaB p65 by western blot. NF-kappaB and CREB DNA-binding activity were measured by electrophoretic mobility shift assay (EMSA). Competition between NF-kappaB and CREB for the coactivator CBP was determined by immunoprecipitation. Interleukin-8 (IL-8) levels in the lung were measured by ELISA.

RESULTS

RL resuscitation produced significantly higher levels of lung IL-8 levels, I-kappaB phosphorylation, p65 phosphorylation, and NF-kappaB DNA binding compared with HSPTX. NF-kappaB-CBP-binding activity was similar in both groups, whereas CREB-CBP-binding activity was significantly increased with HSPTX. CREB-DNA binding-activity increased to a greater level with HSPTX compared with RL.

DISCUSSION

HSPTX decreases lung inflammation following hemorrhagic shock compared with conventional resuscitation using RL through attenuation of NF-kappaB signaling and increased CREB-DNA binding activity. HSPTX may have therapeutic potential in the attenuation of ischemia-reperfusion injury observed after severe hemorrhagic shock.

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.

Beneficial effects of activation of PKC on hemorrhagic shock in rats

BACKGROUND

The reduced vascular reactivity after severe trauma or shock played an important role in the development and outcome of shock. Our previous study showed that protein kinase C (PKC) took part in the regulation of vascular reactivity after hemorrhagic shock. The objective of this study was to investigate the protective effects of activation of PKC on hemorrhagic shock and its related mechanism.

METHODS

Sprague dawley rats were subjected to hemorrhagic shock (40 mm Hg for 2 hours). Effects of the PKC agonist, phorbol-12-myristate-13-acetate (PMA), and its inhibitor, staurosporine, on hemodynamic parameters were observed in vivo or in vitro. The hemodynamic parameters included mean arterial blood pressure, left intraventricular systolic pressure, the maximal change rate of left intraventricular pressure (+/-dp/dtmax), blood gases including pH, Po2, Sao2, and base excess, animal survival time, the vascular reactivity and calcium sensitivity of superior mesenteric artery, and mitochondrial function and blood flow of liver and kidney.

RESULTS

Intravenous administration of PKC agonist, PMA, at the concentration of 1 microg/kg significantly increased the mean arterial blood pressure, left intraventricular systolic pressure, +/-dp/dtmax, the pressor effect, and the contractile response of norepinephrine, it also improved the blood gases, and prolonged the survival time of shocked rats. In addition, the intravenous administration of PMA improved mitochondrial function and liver and kidney blood flow. A total of 10(-7) mol/L of PMA administrated in vitro significantly improved the vascular reactivity and calcium sensitivity of superior mesenteric artery to norepinephrine and Ca2+. These effects of PMA were abolished by the PKC specific inhibitor staurosporine (1 microg/kg in vivo or 10(-7) mol/L in vitro).

CONCLUSION

Activation of PKC has protective effects on hemorrhagic shock. The mechanism is related not only to its hemodynamic stabilization effect via improving vascular reactivity and calcium sensitivity but also to its effect on improving the perfusion and mitochondrial function of vital organs.

Ordered transcriptional factor recruitment and epigenetic regulation of tnf-alpha in necrotizing acute pancreatitis

Tauhe expression of the critical initiator cytokine TNF-alpha was strongly upregulated in vivo in acute necrotic pancreatitis (AP) in rodents and in vitro in TNF-alpha activated acinar AR42J cells. Upregulation of tnf-alpha, inos, icam-1 and il-6 occurred both in TNF-alpha receptor 1 and 2 knock-out mice, but not in TNF-alpha knock-out mice, in cerulein-induced acute pancreatitis. Chromatin immunoprecipitation analysis showed that transcriptional factors (ELK-1, SP1, NF-kappaB and EGR-1) and chromatin modification complexes (HDAC1, HDAC2, GCN5, PCAF and CBP) were recruited and/or released from the promoter in a strictly ordered mechanism. Activation of tnf-alpha gene was also accompanied by an ordered increased level of histone H3K9, H3K14 and H3K18-acetylation and H3K4 methylation, as well as H4K5 acetylation. A better knowledge of the molecular mechanisms that control tnf-alpha gene regulation will provide deeper understanding of the initiation and development of the inflammatory processes occurring in acute pancreatitis triggered by TNF-alpha cytokine.

Fluid resuscitation: past, present, and the future

Hemorrhage remains a major cause of preventable death following both civilian and military trauma. The goals of resuscitation in the face of hemorrhagic shock are restoring end-organ perfusion and maintaining tissue oxygenation while attempting definitive control of bleeding. However, if not performed properly, resuscitation can actually exacerbate cellular injury caused by hemorrhagic shock, and the type of fluid used for resuscitation plays an important role in this injury pattern. This article reviews the historical development and scientific underpinnings of modern resuscitation techniques. We summarized data from a number of studies to illustrate the differential effects of commonly used resuscitation fluids, including isotonic crystalloids, natural and artificial colloids, hypertonic and hyperoncotic solutions, and artificial oxygen carriers, on cellular injury and how these relate to clinical practice. The data reveal that a uniformly safe, effective, and practical resuscitation fluid when blood products are unavailable and direct hemorrhage control is delayed has been elusive. Yet, it is logical to prevent this cellular injury through wiser resuscitation strategies than attempting immunomodulation after the damage has already occurred. Thus, we describe how some novel resuscitation strategies aimed at preventing or ameliorating cellular injury may become clinically available in the future.

Attenuation of the effects of rat hemorrhagic shock with a reperfusion injury-inhibiting agent specific to mice

Death after hemorrhagic shock (HS) may be caused by a generalized reperfusion injury, particularly noticeable in the gut. A period of tissue ischemia followed by reinstitution of perfusion produces severe inflammation that can be blocked in mice by preventing the binding of a pathogenic natural immunoglobulin M (IgM) of defined specificity to antigens in reperfused tissue by using a soluble peptide analogue of the IgM tissue target. We hypothesize that this agent can improve end points of rat HS: death, intestinal injury, and lung injury. Male Sprague-Dawley rats were anesthetized; 50% of calculated blood volume was removed for 120 min, shed blood, then returned; and animals were sacrificed at 72 h. One group of rats received i.v. analogue ([N2] 300 microg) with the return of shed blood. Small intestine and lung were evaluated by histological examination and immunohistochemistry. Lung edema was assessed by Evans blue extravasation and histological examination. I.v. N2 decreased experimental mortality from 62% to 12% (P < 0.05). Associated with this was diminution of gut injury score from 57.8% +/- 5.5% to 19.5% +/- 2.5% (P < 0.05), lung injury from 21.4 +/- 1.5 to 14.8 +/- 1.3 polymorphonuclear leucocytes per high-power field x400 (P < 0.05), and Evans blue extravasation index from 0.61 +/- 0.14 to 0.18 +/- 0.06 (P < 0.05). As well, the deposition of IgM and C3 that is seen in intestinal villi from HS was not present in N2-treated rats. The N2 peptide agent that blocks reperfusion injury in mice prevents death from rat HS, as well as attenuates gut reperfusion injury and its remote target injuries. These data suggest that death from HS is caused by reperfusion injury, and that an agent derived from mice is effective in rats when given in real therapeutic time.

Protective effects of remifentanil on septic mice

This study is to explore the effect of remifentanil on inducible nitric oxide synthase (iNOS) expression, IL-6 and IL-10 levels, myeloperoxidase (MPO) activity, white blood cell count in bronchoalveolar (BALF), ALT and AST activity in septic mice. Forty male KM mice were randomly divided into four groups, sham group, cecal ligation and puncture group (CLP group), remifentanil treatment group (R1 group), and remifentanil control group (R2 group). The mouse model of CLP was used to observe ALT and AST activity, white blood cell count in BALF and myeloperoxidase (MPO). IL-6 and IL-10 in lung and liver tissue were assayed by enzyme-linked immunosorbent assay (ELISA). Lung and liver tissues were harvested for determination of iNOS expression by Western blot analysis. The pathologic changes were observed under electron microscope. Compared with sham group, iNOS protein expression, white blood cell count in BALF, ALT and AST activity, MPO activity, IL-6 and IL-10 levels were markedly increased in CLP group. Compared with CLP group, iNOS protein expression, IL-6 and IL-10 levels, white blood cell count in BALF, ALT and AST activity, MPO activity of R1 group were significantly lower. The pathologic changes induced by sepsis were significantly attenuated by remifentanil under electron microscope. Remifentanil could suppress inflammatory responses and inhibit iNOS expression in septic mice. Remifentanil might have a protective effect against sepsis. Its action mechanisms are probably involved in the inhibition of inflammatory factor production and suppression of iNOS expression.

Burn-induced gut barrier injury is attenuated by phosphodiesterase inhibition: effects on tight junction structural proteins

Loss of intestinal barrier function after burn injury allows movement of intraluminal contents across the mucosa, which can lead to the development of distant organ injury and multiple organ failure. Tight junction function is highly regulated by membrane-associated proteins including occludin and zonula occludens protein 1 (ZO-1), which can be modulated by systemic inflammation. We hypothesized that (1) burn injury leads to gut barrier injury, and (2) phosphodiesterase inhibition will attenuate these burn-induced changes. Male balb/c mice undergoing a 30% steam burn were randomized to resuscitation with normal saline or normal saline + pentoxifylline (PTX; 12.5 mg/kg). Intestinal injury was assessed by histological diagnosis and TNF-alpha levels using enzyme-linked immunosorbent assay. Intestinal permeability was assessed by measuring the plasma concentration of fluorescein isothiocyanate-dextran after intraluminal injection in the distal ileum. Occludin and ZO-1 levels were analyzed by immunoblotting and immunohistochemistry. Thirty percent total body surface area (TBSA) burn results in a significant increase in intestinal permeability. Treatment with PTX after burn attenuates intestinal permeability to sham levels. Burn injury resulted in a marked decrease in the levels of tight junction proteins occludin and ZO-1 at 6 and 24 h. The use of PTX after burn significantly decreases the breakdown of occludin and ZO-1. Pentoxifylline also attenuates the burn-induced increase in plasma and intestinal TNF-alpha. Confocal microscopy demonstrates that PTX attenuates the burn-induced reorganization of occludin and ZO-1 away from the tight junction. Pentoxifylline attenuates burn-induced intestinal permeability and decreases the breakdown and reorganization of intestinal occludin and ZO-1. Therefore, phosphodiesterase inhibition may be a useful adjunct strategy in the attenuation of burn-induced gut barrier injury.

Phosphodiesterase inhibition attenuates alterations to the tight junction proteins occludin and ZO-1 in immunostimulated Caco-2 intestinal monolayers

AIMS

Under normal conditions, the intestinal mucosa acts as a local barrier to prevent the influx of luminal contents. The intestinal epithelial tight junction is comprised of several membrane associated proteins, including zonula occludens-1 (ZO-1) and occludin. Disruption of this barrier can lead to the production of pro-inflammatory mediators and ultimately multiple organ failure. We have previously shown that Pentoxifylline (PTX) decreases histologic gut injury and pro-inflammatory mediator synthesis. We hypothesize that PTX prevents the breakdown of ZO-1 and occludin in an in vitro model of immunostimulated intestinal cell monolayers.

MAIN METHODS

Caco-2 human enterocytes were grown as confluent monolayers and incubated under control conditions, or with PTX (2 mM), Cytomix (TNF-alpha, IFN-gamma, IL-1), or Cytomix+PTX for 24 h. Occludin and ZO-1 protein levels were analyzed by Western blot. Confocal microscopy was used to assess the cytoplasmic localization of ZO-1 and occludin.

KEY FINDINGS

Cytomix stimulation of Caco-2 cells resulted in a 50% decrease in both occludin and ZO-1 protein. Treatment with Cytomix+PTX restored both occludin and ZO-1 protein to control levels. Confocal microscopy images show that Cytomix caused an irregular, undulating appearance of ZO-1 and occludin at the cell junctions. Treatment with PTX prevented the Cytomix-induced changes in ZO-1 and occludin localization.

SIGNIFICANCE

Treatment with PTX decreases the pro-inflammatory cytokine induced changes in the intestinal tight junction proteins occludin and ZO-1. Pentoxifylline may be a useful adjunct in the treatment of sepsis and shock by attenuating intestinal barrier breakdown.

Bench-to-bedside review: latest results in hemorrhagic shock

Hemorrhagic shock is a leading cause of death in trauma patients worldwide. Bleeding control, maintenance of tissue oxygenation with fluid resuscitation, coagulation support, and maintenance of normothermia remain mainstays of therapy for patients with hemorrhagic shock. Although now widely practised as standard in the USA and Europe, shock resuscitation strategies involving blood replacement and fluid volume loading to regain tissue perfusion and oxygenation vary between trauma centers; the primary cause of this is the scarcity of published evidence and lack of randomized controlled clinical trials. Despite enormous efforts to improve outcomes after severe hemorrhage, novel strategies based on experimental data have not resulted in profound changes in treatment philosophy. Recent clinical and experimental studies indicated the important influences of sex and genetics on pathophysiological mechanisms after hemorrhage. Those findings might provide one explanation why several promising experimental approaches have failed in the clinical arena. In this respect, more clinically relevant animal models should be used to investigate pathophysiology and novel treatment approaches. This review points out new therapeutic strategies, namely immunomodulation, cardiovascular maintenance, small volume resuscitation, and so on, that have been introduced in clinics or are in the process of being transferred from bench to bedside. Control of hemorrhage in the earliest phases of care, recognition and monitoring of individual risk factors, and therapeutic modulation of the inflammatory immune response will probably constitute the next generation of therapy in hemorrhagic shock. Further randomized controlled multicenter clinical trials are needed that utilize standardized criteria for enrolling patients, but existing ethical requirements must be maintained.

Pentoxifylline attenuates pulmonary inflammation and neutrophil activation in experimental acute pancreatitis

OBJECTIVES

Acute pancreatitis (AP) is associated with a systemic inflammatory response. Pentoxifylline (PTX) has been shown to attenuate neutrophil activation and end-organ injury in shock states such as hemorrhage and sepsis. We hypothesized that PTX would down-regulate AP-induced lung injury.

METHODS

Sprague-Dawley rats underwent catheterization of the pancreatic duct. Acute pancreatitis (n = 7) and AP/PTX animals (n = 7) received a retrograde infusion of 3.5% sodium taurocholate and intravenous treatment with normal saline or normal saline and PTX (25 mg/kg), respectively. Pulmonary neutrophil degranulation and sequestration were determined by zymography and detection of myeloperoxidase. Nuclear factor kappa B and mitogen-activated protein kinase phosphorylation was determined by Western blot. Cytokine-induced neutrophil chemoattractant was quantified by enzyme linked immunosorbent assay.

RESULTS

Pulmonary histologic injury scores were attenuated in the AP/PTX group (P < 0.05). Plasma amylase levels remained unchanged. Pentoxifylline produced a significant decline in myeloperoxidase content and matrix metalloproteinase activity (P < 0.05). The increase in the phosphorylation of pulmonary nuclear factor kappa B, p38 mitogen-activated protein kinase, and extracellular-related signal kinase 1/2 observed after AP was not demonstrated with PTX (P < 0.05). Pentoxifylline supplementation reduced pulmonary cytokine-induced neutrophil chemoattractant levels by 50% (P < 0.05).

CONCLUSIONS

Pentoxifylline significantly attenuated histologic lung injury, pulmonary neutrophil activity, and proinflammatory signaling in a severe model of AP. Therefore, PTX may serve as an adjunct for the treatment of the inflammatory complications of severe AP.

Hepatic transcription factor activation and proinflammatory mediator production is attenuated by hypertonic saline and pentoxifylline resuscitation after hemorrhagic shock

BACKGROUND

Fluid resuscitation can contribute to postshock inflammation and the development of end organ injury. We have previously observed an attenuation in pulmonary and ileal inflammation when hypertonic saline and pentoxifylline (HSPTX) were concomitantly administered after hemorrhage. We hypothesized that the attenuation in hepatic injury observed with HSPTX is associated with the reduction of transcription factor activation and proinflammatory mediator production when compared with Ringer's lactate (RL).

METHODS

Male Sprague-Dawley rats were resuscitated with racemic RL (32 mL/kg) or HSPTX (4 mL/kg 7.5% NaCl + PTX 25 mg/kg) and killed at 4 hours and 24 hours after resuscitation. Liver injury was determined by histology and serum aminotransferases. Nitrite, tumor necrosis factor-alpha, interleukin (IL)-1beta, and IL-6 were measured with enzyme-linked immunosorbent assay. High mobility group box 1, inducible nitric oxide synthase, nuclear factor (NF)-kappaB phosphorylation, and signal transducers and activators of transcription-3 phosphorylation were determined by Western blot. Transcription factor activation was verified with Electrophoretic Mobility Shift Assay.

RESULTS

RL resuscitation led to significant increases all measured parameters when compared with control. In contrast, HSPTX did not induce elevations in histologic liver injury or alanine aminotransferase levels. HSPTX attenuated inducible nitric oxide synthase by 23% (p < 0.01), nitrite by 25% (p < 0.05), tumor necrosis factor-alpha by 25% (p < 0.05), IL-1 by 63% (p < 0.01), IL-6 by 35% (p < 0.05), and high mobility group box 1 by 39% (p < 0.05) when compared with RL. HSPTX reduced IkappaB-alpha phosphorylation by 34% (p < 0.05), NF-kappaB p65 phosphorylation by 75% (p < 0.01), and signal transducers and activators of transcription-3 phosphorylation by 52% (p < 0.01).

CONCLUSIONS

The reduction in liver injury observed with HSPTX resuscitation after hemorrhage is associated with attenuation transcription factor activation and proinflammatory mediators. HSPTX has the potential to be a superior resuscitation fluid with significant immunomodulatory properties.

Insights into the regulation of TNF-alpha production in human mononuclear cells: the effects of non-specific phosphodiesterase inhibition

OBJECTIVE

The objective of this study was to determine the effect of nonspecific phosphodiesterase inhibition on transcription factor activation and tumor necrosis factor-alpha (TNF-alpha) production in lipopolysaccharide (LPS)-stimulated human mononuclear cells.

INTRODUCTION

The production of TNF-alpha following LPS stimulation is one of the key steps in bacterial sepsis and inflammation. The mechanism by which phosphodiesterase inhibition alters TNF-alpha production in the presence of LPS remains unclear.

METHODS

Human mononuclear cells were stimulated with LPS (1 microg/mL), in the presence and absence of Pentoxifylline (PTX; 20 mM), a nonspecific phosphodiesterase inhibitor. Western blotting of phosphorylated cytoplasmic I-kBalpha, nuclear factor-kB p65 (NF-kB), and nuclear cAMP-response element binding protein (CREB) was performed. DNA binding of NF-kB and CREB was verified by electrophoretic mobility shift assay. TNF-a levels were determined in the supernatant of stimulated cells in the presence and absence Protein kinase A inhibition by an enzyme-linked immunosorbent assay (ELISA).

RESULTS

PTX was demonstrated to significantly reduce cytoplasmic I-kBalpha phosphorylation, nuclear p65 phosphorylation, and the DNA binding activity of NF-kB. In contrast, PTX markedly enhanced the phosphorylation and DNA binding activity of CREB. Cells concomitantly treated with PTX and LPS secreted similar levels of TNF-a in the presence and absence Protein kinase A inhibition.

DISCUSSION

The increased level of cAMP that results from phosphodiesterase inhibition affects cytoplasmic and nuclear events, resulting in the attenuation of NF-kB and the activation of CREB transcriptional DNA binding through pathways that are partially Protein kinase A-independent.

CONCLUSION

PTX-mediated phosphodiesterase inhibition occurs partially through a Protein kinase A-independent pathway and may serve as a useful tool in the attenuation of LPS-induced inflammation.

Effect of TLR-4 and HO-1 on acute lung injury induced by hemorrhagic shock in mice

OBJECTIVE

To examine whether TLR-4 has an effect on hemorrhage induced changes in lung, and to investigate the change of heme oxygenase-1 (HO-1) on acute lung injury (ALI) induced by hemorrhagic shock in mice.

METHODS

Forty-eight male mice, including C3H/HeN mice and C3H/HeJ mice, were randomly divided into sham group (n=12), hemorrhagic shock group with twelve mice in each phase. Blood pressure (BP) was monitored continuously by attaching carotid artery catheter to a strain gauge pressure transducer/ polygraph. Arterial blood samples were taken for blood gas analysis. A mouse model of non-lethal hemorrhagic shock and resuscitation was used to observe pulmonary myeloperoxidase (MPO) activity and wet/dry weight ratio (W/D). The expression of HO-1 was observed by means of RT-PCR and immunohistochemistry. IL-6 and IL-10 in lung tissue homogenate were assayed by enzyme-linked immunosorbent assay (ELISA). The pulmonary pathologic changes were observed under electron microscope and light microscope.

RESULTS

Compared with sham group, the expression of HO-1 in lung tissue was significantly higher in Hem 24 h and Hem 48 h of C3H/HeN mice (P less than 0.01). The expression of HO-1 mRNA and the levels of IL-6, IL-10 and MPO in lung tissue were markedly increased in Hem 24 h (P less than 0.01 or P less than 0.05); Compared with C3H/HeN mice, the expression of HO-1 mRNA and the levels of IL-6 and IL-10 in C3H/HeJ mice significantly decreased in Hem 24 h and Hem 48 h (P less than 0.01 or P less than 0.05), and the W/D, MPO in C3H/HeJ mice were obviously lower in Hem 24 h (P less than 0.05). The injuries of lung tissues after hemorrhagic shock have been demonstrated by histological examination with electron microscope and light microscope.

CONCLUSIONS

TLR-4 and HO-1 might modulate the balance of pro- and anti-inflammatory processes in inflammatory reaction of hemorrhagic shock-induced ALI, and the activation of Toll-like receptor might induce the transcription activity of HO-1, which may play a key role in acute lung injury.

From acute pancreatitis to end-organ injury: mechanisms of acute lung injury

BACKGROUND

Multi-organ dysfunction, and in particular lung injury, is often responsible for the unfavorable outcome of patients with severe acute pancreatitis. Understanding of the mechanisms by which local inflammation in the pancreas leads to end-organ injury is crucial for the development of new therapeutic strategies.

METHODS

A MEDLINE search was performed with the terms "acute pancreatitis," "lung injury," "inflammatory response," "SIRS," and "multi-organ dysfunction." Pertinent articles were selected for analysis.

RESULTS

Modulation of the inflammatory response using a combination of immunomodulatory agents may decrease the incidence of severe pancreatitis-related acute lung injury and acute respiratory distress syndrome.

CONCLUSION

Clinical trials are of utmost importance to establish the validity of such strategies.

The effects of a novel resuscitation strategy combining pentoxifylline and hypertonic saline on neutrophil MAPK signaling

BACKGROUND

The combination of hypertonic saline (HS) and pentoxifylline (PTX) has been shown to synergistically downregulate neutrophil oxidative burst in vitro. We investigated the effects of HS/PTX on human neutrophil mitogen-activated protein kinase (MAPK) signaling and the role of Protein kinase A (PKA) in this process.

METHODS

Isolated neutrophils were treated with PTX (2 mmol/L), HS10 (10 mmol/L above isotonicity), and HS40 (40 mmol/L above isotonicity) alone or in combination for determination of intracellular cyclic adenosine monophosphate (cAMP) concentrations. Human neutrophils were stimulated with f-methionyl-leucyl-phenylalanine (fMLP) (1 micromol/L) before the treatments above in both the presence and the absence of PKA inhibition for Western blot analysis of MAPK p38 and extracellular signal-related kinase 1/2 (ERK 1/2) phosphorylation.

RESULTS

Concomitant exposure to HS/PTX results in an additive increase in intracellular cAMP. fMLP-induced ERK 1/2 phosphorylation was synergistically attenuated by HS/PTX. Both PTX and HS reduced p38MAPK phosphorylation. No additive effect was observed with combined treatment. Although PKA inhibition abrogated the effects of PTX, HS retained some capacity to attenuate MAPK phosphorylation.

CONCLUSION

HS/PTX is more effective in attenuating neutrophil ERK signaling than either component alone, whereas both components alone or in combination produced comparable results with p38MAPK. Although PTX functions primarily through PKA activation, HS may suppress neutrophils through a partially PKA-independent mechanism.

Hypertonic saline and pentoxifylline attenuates gut injury after hemorrhagic shock: the kinder, gentler resuscitation

BACKGROUND

We have previously demonstrated that postshock resuscitation with Hypertonic saline and Pentoxifylline (HSPTX) attenuates pulmonary and histologic gut injury when compared with Ringer's lactate (RL). In this study, we hypothesized that the decrease in gut injury observed with HSPTX is associated with the attenuation of inducible nitric oxide synthase (iNOS) activity and production of ileal proinflammatory mediators after hemorrhagic shock.

METHODS

In a rat model of hemorrhagic shock, resuscitation was conducted with RL (32 mL/kg; n = 7) or HSPTX (4 mL/kg 7.5% NaCl + PTX 25 mg/kg; n = 7). Sham animals that did not undergo shock were also studied. Four hours after resuscitation, the terminal ileum was collected for evaluation of nitrite, tumor necrosis factor (TNF)-alpha, Interleukin (IL)-6, and cytokine-induced neutrophil chemoattractant (CINC) by enzyme immunoassay. Heme oxygenase-1 (HO-1), iNOS, cytoplasmic inhibitor of kappa B (Ikappa B) phosphorylation, and nuclear factor (NF)kappa B p65 nuclear translocation were determined by Western blot.

RESULTS

HSPTX resuscitation resulted in a 49% decrease in iNOS when compared with RL (p < 0.05). Similar results were obtained when examining nitrite (882 +/- 59 vs. 1,435 +/- 177 micromol/L; p < 0.01), and HO-1 content (p < 0.05). RL resuscitation resulted in markedly higher levels of TNF-alpha (83 +/- 27 vs. 9 +/- 5 pg/mL; p < 0.01), IL-6 (329 +/- 58 vs. 118 +/- 43 pg/mL; p < 0.05), and CINC (0.43 +/- .06 vs. 0.19 +/- .08 ng/mL; p < 0.05) than HSPTX. The increase in cytokines observed with RL was also associated with an increase in I-kappaB phosphorylation (p < 0.01) and NF-kappaB p65 nuclear translocation (p < 0.001).

CONCLUSION

The attenuation in gut injury after postshock resuscitation with HSPTX is associated with downregulation of iNOS activity and subsequent proinflammatory mediator synthesis. HSPTX has the potential to be a superior resuscitation fluid with significant immunomodulatory properties.

Hypertonic saline and pentoxifylline reduces hemorrhagic shock resuscitation-induced pulmonary inflammation through attenuation of neutrophil degranulation and proinflammatory mediator synthesis

BACKGROUND

Ringer's lactate (RL), the current standard resuscitation fluid, potentiates neutrophil activation and is associated with pulmonary inflammation. Resuscitation with hypertonic saline and pentoxifylline (HSPTX) has been shown to attenuate hemorrhagic shock-induced injury when compared with RL. Because the neutrophil plays a major role in postshock inflammation, we hypothesized that HSPTX reduces pulmonary inflammation after resuscitation in comparison to RL.

METHODS

Sprague-Dawley rats underwent controlled shock and were resuscitated with RL (32 mL/kg) or HSPTX (4 mL/kg 7.5% NaCl + pentoxifylline 25 mg/kg). Animals who did not undergo shock or resuscitation served as controls. After 24 hours, bronchoalveolar lavage fluid (BALF) and lung tissue were collected. Cytokine induced neutrophil chemoattractant (CINC) was measured in BALF by enzyme-linked immunosorbent assay. Matrix metalloproteinases (MMP)-2 and -9 were measured by zymography. Hemeoxygenase-1 (HO-1) was assessed by Western blot and immunohistochemistry.

RESULTS

HSPTX resuscitation led to a 62% decrease in CINC levels compared with RL (p < 0.01). BALF MMP-2 expression was attenuated by 11% with HSPTX (p = 0.09). Lung MMP-2 and MMP-9 expression was reduced by 89% (p < 0.01) and 76%, respectively (p < 0.05). Lung HO-1 expression declined by 34% with HSPTX in comparison to RL (p < 0.01), indicating less oxidative injury. Lung immunohistochemistry localized HO-1 to neutrophils, macrophages, and airway epithelial cells.

CONCLUSION

Collectively, the attenuation of pulmonary inflammation with HSPTX after shock when compared with RL is associated with downregulation of neutrophil activation, oxidative stress, and proinflammatory mediator production.

Effects of Pentoxifylline on Differentiation, Maturation, and Function of Human CD14+ Monocyte-derived Dendritic Cells

Pentoxifylline (PTX) is a nonspecific phosphodiesterase inhibitor which has potent immunoregulatory and antiinflammatory effects. Although its immunomodulation property has been recognized, it is not clear whether PTX could affect dendritic cells (DCs), the most efficient antigen-presenting cells. The purpose of this study was to determine whether PTX could suppress DC differentiation, maturation, and its associated functions. Immature DCs (iDCs) were generated from human peripheral blood mononuclear cell CD14+ monocytes cultured with granulocyte macrophage colony stimulating factor and interleukin-4 for 5 days. PTX concentration-dependently suppressed the expression of iDC differentiation markers including CD54, CD80, CD86, and human leukocyte antigen-DR. In addition, PTX also inhibited DC maturation marker CD83 expression after stimulating DCs with lipopolysaccharide. Furthermore, PTX inhibited the antigen-uptake ability of DCs when tested by fluorescein isothiocyanate-dextran endocytosis assay. PTX significantly reduced the production of TNF-alpha and IFN-gamma in mature DCs (mDCs). Consequently, PTX-treated mDCs showed a reduced activity of mDC-induced T-cell allostimulation and proliferation by mixed-lymphocyte reaction (MLR) assay. Therefore, PTX significantly inhibits CD14+ monocyte-derived DC differentiation, maturation, antigen-uptake ability of iDCs, and antigen-presentation ability of mDCs possibly due to the suppression of TNF-alpha and IFN-gamma production. These results suggested that inhibitory effects of PTX on DCs may contribute its antiinflammatory and immunoregulatory functions.

Pentoxifylline attenuates stored blood-induced inflammation: A new perspective on an old problem

BACKGROUND

Blood transfusion is a risk factor for many inflammatory processes. Its supernatant fraction has been proven to activate neutrophils. We hypothesized that pentoxifylline (PTX) would attenuate stored blood-induced neutrophil activation and pro-inflammatory mediator production.

METHODS

Whole blood was incubated with HBSS, LPS (100 microg/mL), leukoreduced PRBC supernatant + LPS, or supernatant + LPS + PTX (2 mmol/L). TNF-alpha levels were measured by ELISA. MMP-9 was evaluated with zymography. Neutrophil CD66b expression was determined by flow cytometry in blood treated with HBSS, fMLP (1 micromol/L), supernatant + fMLP, or supernatant + fMLP + PTX.

RESULTS

TNF-alpha levels were elevated in both the LPS and supernatant + LPS groups (100%; P < 0.01 and 120%; P < 0.01, respectively). PTX administration resulted in a 106% decrease in TNF-alpha (P < 0.0001). MMP-9 levels were increased in all groups. Administration of PTX to the supernatant + LPS group generated a 33% decrease in MMP-9 levels, which was not statistically significant (P < 0.4). Upregulation of CD66b expression was seen in LPS and supernatant + LPS groups. Significant attenuation was seen with PTX (47%; P < 0.01).

CONCLUSIONS

PTX downregulates CD66b and TNF-alpha expression in supernatant-induced whole blood. Because blood transfusion can contribute to inflammatory injury, the adjunctive use of PTX may have therapeutic potential.

Neutrophil degranulation and the effects of phosphodiesterase inhibition

BACKGROUND

Neutrophils play a major role as the first line in host defense after exposure to bacterial products. However, an exaggerated inflammatory response characterized by overwhelming neutrophil activation can be injurious to the host. Pentoxifylline (PTX), a nonspecific phosphodiesterase inhibitor, has been shown to attenuate neutrophil oxidative burst and decrease proinflammatory mediator synthesis. We hypothesized that PTX down-regulates neutrophil activation by decreasing the surface expression of both CD35 and CD66b, two markers of neutrophil degranulation.

MATERIALS AND METHODS

Venous blood was obtained from three healthy volunteers. Whole blood was incubated with HBSS (control), f-methionyl-leucyl-phenylalanine (fMLP, 1 microM/L), PTX (2 mM/L), or fMLP + PTX. CD35 and CD66b expression were measured by flow cytometry.

RESULTS

fMLP treatment caused a significant increase in CD35 and CD66b expression of when compared to controls (P < 0.01). PTX treatment revealed expression of both markers comparable to the control group. A 38% decrease in CD35 (64 +/- 12 versus 100; P < 0.01) and a 52% decrease in CD66b (48 +/- 7 versus 100; P < 0.01) expression were demonstrated in the fMLP + PTX group when compared to fMLP alone.

CONCLUSION

In addition to the known effects of PTX on neutrophil oxidative burst, PTX also affects neutrophil degranulation, an essential step in enzyme release and subsequent tissue injury. These findings may have clinical relevance in the treatment of disease processes due to inflammation in which primed neutrophils play a role.

Lidocaine depresses splenocyte immune functions following trauma-hemorrhage in mice

Traumatic and/or surgical injury as well as hemorrhage induces profound suppression of cellular immunity. Although local anesthetics have been shown to impair immune responses, it remains unclear whether lidocaine affects lymphocyte functions following trauma-hemorrhage (T-H). We hypothesized that lidocaine will potentiate the suppression of lymphocyte functions after T-H. To test this, we randomly assigned male C3H/HeN (6-8 wk) mice to sham operation or T-H. T-H was induced by midline laparotomy and approximately 90 min of hemorrhagic shock (blood pressure 35 mmHg), followed by fluid resuscitation (4x shed blood volume in the form of Ringer lactate). Two hours later, the mice were killed and splenocytes and bone marrow cells were isolated. The effects of lidocaine on concanavalin A-stimulated splenocyte proliferation and cytokine production in both sham-operated and T-H mice were assessed. The effects of lidocaine on LPS-stimulated bone marrow cell proliferation and cytokine production were also assessed. The results indicate that T-H suppresses cell proliferation, Th1 cytokine production, and MAPK activation in splenocytes. In contrast, cell proliferation, cytokine production, and MAPK activation in bone marrow cells were significantly higher 2 h after T-H compared with shams. Lidocaine depressed immune responses in splenocytes; however, it had no effect in bone marrow cells in either sham or T-H mice. The enhanced immunosuppressive effects of lidocaine could contribute to the host's enhanced susceptibility to infection following T-H.

HSPTX protects against hemorrhagic shock resuscitation-induced tissue injury: an attractive alternative to Ringer's lactate

BACKGROUND

Conventional fluid resuscitation with Ringer's lactated (RL) activates neutrophils and causes end-organ damage. We have previously shown that HSPTX, a combination of small volume hypertonic saline (HS) and pentoxifylline (PTX), a phosphodiesterase-inhibitor, downregulates in vitro neutrophil activation and proinflammatory mediator synthesis. Herein, we hypothesized that HSPTX decreases end-organ injury when compared with RL in an animal model of hemorrhagic shock.

METHODS

Sprague-Dawley rats were bled to a mean arterial pressure of 35 mm Hg for 1 hour. Animals were divided into 3 groups: sham (no shock, no resuscitation, n = 7), RL (32 mL/kg, n = 7), and HSPTX (7.5% NaCl 4 mL/kg + PTX 25 mg/kg; n = 7). Shed blood was infused after fluid resuscitation. Blood pressure was monitored until the end of resuscitation. Animals were sacrificed at 24 hour after resuscitation. Bronchoalveolar lavage fluid (BALF) was obtained for white cell count (total and differential) and TNF-alpha and IL-1beta levels were measured by ELISA. Lung and intestinal injury at 24 hour were evaluated by histopathology. Organ damage was graded by a pathologist and a score was created (0 = no injury; 3 = severe). Lung neutrophil infiltration was evaluated by MPO immune staining.

RESULTS

There were no differences in mean arterial pressure between groups. At 24 hours, BALF leukocyte count was decreased by 30% in HSPTX animals (p < 0.01). TNF-alpha and IL-1beta levels were markedly decreased in HSPTX-resuscitated animals compared with their RL counterparts (p < 0.01). HSPTX-resuscitated animals (lung injury score = 1.0 +/- 0.4) had markedly decreased acute lung injury compared with RL-treated animals (2.5 +/- 0.3) (p < 0.01). RL resuscitation led to a two-fold increase in lung neutrophil infiltration whereas in HSPTX-treated animals, the number of MPO + cells was similar to sham animals (p < 0.001). Intestinal injury was markedly attenuated by HSPTX (1.1 +/- 0.3) compared with RL animals (2.6 +/- 0.4) (p < 0.001).

CONCLUSIONS

HSPTX, a small volume resuscitation strategy with marked immunomodulatory potential led to a marked decrease in end-organ damage. HSPTX is an attractive alternative to RL in hemorrhagic shock resuscitation.

LPS-Induced Acute Lung Injury is Attenuated by Phosphodiesterase Inhibition: Effects on Proinflammatory Mediators, Metalloproteinases, NF-??B, and ICAM-1 Expression

BACKGROUND

Acute endotoxemia is characterized by an enhanced inflammatory response. Pentoxifylline (PTX), a phosphodiesterase inhibitor, has been shown to decrease TNF-alpha levels and to down-regulate neutrophil activation, likely because of increases in intracellular cyclic AMP. Its effects on lipopolysaccharide (LPS) induced lung injury, more specifically on tissue neutrophil infiltration and degranulation, adhesion molecule expression, and transcriptional factor activation, have not been fully investigated. We postulated that PTX treatment in acute endotoxemia downregulates the inflammatory response and may decrease lung injury.

METHODS

Male Sprague-Dawley rats were randomized into three groups: Sham (saline i.v.), LPS (5 mg/kg i.v.), and PTX + LPS (25 mg/kg and 5 mg/kg i.v., respectively; concomitant injection). After 4 hours, bronchoalveolar lavage fluid (BAL), plasma, and lungs were sampled. BAL IL-8 (ELISA), BAL MMP-2, plasma MMP-9, and BAL MMP-9 (Zymography) were measured. Lung histology (H&E), in addition to lung MPO, ICAM-1, and NF-kappaB expression evaluated by immunohistochemistry were analyzed. Lung NF-kappaB DNA binding was evaluated by electrophoretic mobility shift assay.

RESULTS

PTX treatment decreased BAL IL-8 levels, BAL MMP-2, and plasma MMP-9 activity. Lung neutrophil infiltration (MPO), ICAM-1 expression and NF-kappaB activation were decreased by PTX. In addition, PTX treatment caused a marked attenuation of LPS-induced lung injury.

CONCLUSIONS

Phosphodiesterase inhibition by PTX attenuates LPS-induced end-organ injury. In addition, proinflammatory cytokine production is also downregulated, likely because of the marked attenuation of NF-kappaB DNA binding and activation.

Phosphodiesterase Inhibition Attenuates Stored Blood-Induced Neutrophil Activation: A Novel Adjunct to Blood Transfusion

BACKGROUND

Activated neutrophils play a central role in the pathogenesis of ARDS and multiple organ failure (MOF). Transfusion of packed red blood cells (PRBCs) is an independent risk factor in the development of ARDS and MOF. It has been postulated that factors present in the supernatant of PRBCs activate neutrophils. The magnitude of neutrophil activation is dependent on the age of the stored blood. Our laboratory and others have reported that pentoxifylline (PTX), a nonspecific phosphodiesterase inhibitor, decreases neutrophil activation. We hypothesized that adding PTX to PRBCs would attenuate blood transfusion-induced neutrophil activation.

STUDY DESIGN

Peripheral blood was obtained from healthy human volunteers. Oxidative burst, CD11b, and CD35 expression were measured by flow cytometry using a whole blood preparation. Whole blood was incubated with N-formyl-methionyl-leucyl-phenylalanine (fMLP) (1 microM) alone and 42-day-old PRBC supernatant + fMLP with or without PTX (2 mmol/L).

RESULTS

N-formyl-methionyl-leucyl-phenylalanine alone caused a significant increase in neutrophil oxidative burst (100%). The exposure of whole blood to PRBC supernatants + fMLP led to a 1.3-fold increase in neutrophil oxidative burst as compared with fMLP alone, indicating that PRBC supernatants prime neutrophils for oxidative burst by 75%. More importantly, PTX decreased neutrophil oxidative burst by 114% in supernatant + fMLP-stimulated whole blood (p < 0.001). PTX decreased CD11b expression in both fMLP (p < 0.01) and fMLP+supernatant-stimulated whole blood (p < 0.05). Supernatant from PRBCs did not have an additive effect to fMLP alone on CD11b expression. N-formyl-methionyl-leucyl-phenylalanine-induced CD35 expression was downregulated by PTX. The addition of PRBC supernatant did not increase the already upregulated fMLP-induced CD35 expression.

CONCLUSIONS

Our results suggest that adding PTX to PRBC supernatant markedly decreases neutrophil activation. The lack of successful treatment strategies to effectively modulate the inflammatory response after blood transfusion indicates the need for novel therapies. Because the deleterious effects of blood transfusion on end-organ injury and MOF are associated with neutrophil activation, the adjunct use of PTX to blood transfusion may have therapeutic potential.

Immunomodulation, part I: pentoxifylline

PTXF appears to be a promising adjunct to antibiotic therapy in neonatal sepsis. No adverse effects were noted in either study reported in the literature. However, there is a need for large randomized clinical trials to confirm or refute the role of PTXF in the treatment of sepsis in neonates. Clinically important comorbidities such as chronic lung disease, periventicular leukomalacia, duration of assisted ventilation, and NEC should be evaluated as a part of these studies. Comparison of PTXF with immunomodulatory agents such as colony-stimulating factors and intravenous immunoglobulins is suggested. Part II of this five-part series on immunomodulation will explore the use of colony-stimulating factors in neonates. Other topics will include the amino acid glutamine, intravenous immunoglobulins, and probiotics.

Lymphatic system as a path underlying the spread of lung and gut injury after intestinal ischemia/reperfusion in rats

We investigated in rats the influence of the lymphatic system and of tumor necrosis factor (TNF) on the lung inflammation resulting from intestinal ischemia/reperfusion (I/R) performed by 45-min occlusion of the superior mesenteric artery followed by 2 h of reperfusion. A group of rats had the thoracic lymph duct ligated before I/R. In lungs, intestinal I/R evoked a significant neutrophil recruitment, and enhanced microvascular permeability, in addition to generation of TNF in serum. In the gut, there was lowered lactate dehydrogenase (LDH) activity and increased microvascular permeability. Upon lymph duct ligation, I/R rats had a significant reduction of pulmonary neutrophil recruitment and plasma extravasation, in addition to high amounts of TNF in the lymph, contrasting with undetectable levels in the serum. In addition, LDH gut levels in these animals were close to basal values; there was also some (yet significant) reduction of microvascular permeability, suggesting that the ligation of the lymphatic duct exerted some degree of protection against the intestinal injury caused by I/R. In I/R rats, the treatment with pentoxifylline (PTX) reduced TNF in serum and blunted other lung alterations. The gut alterations caused by intestinal I/R were largely blocked by PTX. On the other hand, in I/R rats with lymph duct ligation, PTX exacerbated the reduction of pulmonary neutrophil recruitment, but did not affect pulmonary and intestinal microvascular permeabilities. Similarly, intestinal LDH activity and serum TNF levels were unaffected. Overall, our data show that the pulmonary and gut injuries induced by intestinal I/R are partially dependent on TNF, which is conceivably generated in the injured gut tissue due to intestinal I/R and carried by the lymphatic system. Thus, the mesenteric lymphatic drainage seems to play a role as a path modulator of the pulmonary and intestinal dysfunctions that follow a gut trauma.

Nonspecific phosphodiesterase inhibition attenuates liver injury in acute endotoxemia

BACKGROUND

Endotoxemia is accompanied by pro-inflammatory cytokine production, generation of reactive oxygen species, and end-organ injury. Pentoxifylline (PTX), a methylxanthine derivative and phosphodiesterase inhibitor, is known for its anti-inflammatory properties, including down-regulation of interleukin (IL)-6 and tumor necrosis factor (TNF)-alpha synthesis. Its effects on liver function and hepatic histology following acute endotoxemia have not been investigated fully. We hypothesized that PTX would preserve liver architecture and function after intravenous lipopolysaccharide (LPS) injection.

METHODS

Anesthetized Sprague-Dawley rats received an i.v. bolus injection of LPS (5 mg/kg), LPS + PTX (25 mg/kg), or saline (sham). Plasma concentrations of alanine aminotransferase (ALT), aspartate aminotransferase (AST), TNF-alpha, IL-6, and nitrite were measured at different time points after LPS injection. Liver injury was graded according to a scoring system in a blinded fashion from 0 (normal) to 4 (severe) for hepatocellular necrosis, hemorrhage, and parenchymal and sinusoidal inflammatory infiltrates. Neutrophil infiltration was measured by counting myeloperoxidase (MPO)-positive stained cells. Nuclear factor (NF)-kappaB p-65 was measured by counting positive stained nuclei of hepatocytes and Kupffer cells (KC). Inducible nitric oxide synthase (iNOS) was evaluated by positively stained KC. Data are presented as mean +/- SEM. Analysis of variance with p < 0.05 was considered statistically significant.

RESULTS

Animals treated with PTX showed a significant reduction in liver injury score and neutrophil infiltration. Treatment with PTX significantly decreased TNF-alpha, IL-6, and the concentrations of AST and ALT when compared to LPS alone. In addition, a significant decrease in NF-kappaB-positive staining in hepatocytes and KC, as well as in KC iNOS immunostaining was observed in PTX-treated animals compared to the LPS group.

CONCLUSIONS

Pentoxifylline downregulates the inflammatory response significantly and decreases liver injury in acute endotoxemia.

LPS-Stimulated PMN Activation and Proinflammatory Mediator Synthesis is Downregulated by Phosphodiesterase Inhibition: Role of Pentoxifylline

BACKGROUND

Excessive production of reactive oxygen species by PMN is associated with tissue damage during inflammation. LPS interacts with the cell surface receptor CD14, which generates transmembrane signals through Toll-like protein 4 leading to mitogen activated protein kinase (MAPK) p38 activation, cytokine synthesis, PMN beta2-integrin expression and oxidative burst. Phosphodiesterase inhibition decreases proinflammatory cytokine production and tissue injury after LPS challenge. Its effects on PMN function after LPS stimulation, however, have not been fully investigated. We hypothesized that LPS-induced TNF-alpha synthesis and subsequent PMN beta2-integrin expression and oxidative burst are downregulated by concomitant treatment with the non-specific phosphodiesterase inhibitor pentoxifylline (PTX).

METHODS

Whole blood was incubated with HBSS (control), LPS (100 microg/mL), fMLP (1 micromol/L), LPS+PTX (2 mmol/L) and fMLP+PTX for different time intervals at 37C. Oxidative burst, CD14, and CD-11b expression were measured by flow cytometry. Serum TNF-alpha levels were measured by ELISA. In an attempt to localize the site of action of PTX (proximal or distal to PKC) cell surface receptors were bypassed by PMA stimulation (1 microg/mL) and oxidative burst was measured with and without PTX.

RESULTS

Up-regulation of CD14 expression was similar in LPS and LPS+PTX groups. LPS stimulation caused a significant increase in PMN oxidative burst, CD11b expression, and TNF-alpha serum levels. In addition, PMA and fMLP stimulation also caused significant increase in oxidative burst compared with controls. Concomitant addition of PTX to LPS led to a significant decrease in PMN oxidative burst (65%; p < 0.0001), PMN CD11b expression (20%; p = 0.012), and TNF-alpha levels (93%; p < 0.0001). Also, PMA- and fMLP-induced PMN oxidative burst were significantly decreased by PTX [77.5% (p < 0.0001) and 50% (p < 0.01), respectively].

CONCLUSIONS

These results suggest that PTX-inhibition of oxidative burst occurs distal to PKC and may be either due to direct inhibition of NADPH oxidase or inhibition of MAPK phosphorylation, leading to decreased adhesion molecule expression and TNF-alpha synthesis. Its use in clinical scenarios in which PMN are primed may be of clinical relevance.