Dexamethasone and pentoxifylline inhibit endotoxin-induced cachectin/tumor necrosis factor synthesis at separate points in the signaling pathway

Corticosteroid plus pentoxifylline is not better than corticosteroid alone for improving survival in severe alcoholic hepatitis (COPE trial)

BACKGROUND

Corticosteroids and pentoxifylline reduce short-term mortality in severe alcoholic hepatitis (SAH), but not to the extent desired. Combining both drugs may lead to better survival, but has not yet been studied.

AIM

To compare the efficacy of corticosteroids plus pentoxifylline with that of corticosteroids alone in improving survival of SAH patients.

METHODS

Of the 111 patients screened, 70 patients with SAH (Maddrey discriminant function (MDF) ≥ 32) were enrolled. Patients with active infection, bleeding, renal failure, or pancreatitis were excluded. Treatment was given for four weeks to group A (n = 36; prednisolone 40 mg/day plus pentoxifylline 400 mg thrice/day) and group B (n = 34; prednisolone 40 mg/day). Patients were followed up for 6 months. Data are expressed as median (range) or percentage.

RESULTS

Baseline characteristics of the two groups were similar (MDF group A 78.5 (36.8-140.9), group B 74.9 (45.6-140.2)). Four-week and six-month survival in groups A and B were not significantly different (four-week 72.2 and 73.5%, respectively, p = 1.00; six-month 30.6 and 23.5%, respectively, p = 0.417). At seven days, 55.6% of patients in group A and 64.7% in group B had a Lille score <0.45 (p = 0.473). Six-month survival was significantly higher for patients with a Lille Score <0.45 than for those with a Lille score ≥0.45 (group A 55.5 vs. 0%, p = 0.0006; group B 36 vs. 0%, p = 0.0304). Biological improvement at 28 days was significant for both groups; however, the difference between the groups was not significant.

CONCLUSIONS

For patients with severe alcoholic hepatitis, a combination of corticosteroids and pentoxifylline has no additional survival advantage compared with corticosteroids alone.

Pentoxifylline for endometriosis

BACKGROUND

Endometriosis is a chronic, recurring condition that occurs during the reproductive years. It is characterized by endometrial tissue developing outside the uterine cavity. This endometrial tissue development is dependent on oestrogen produced primarily by the ovaries and, therefore, traditional management has focused on ovarian suppression. In this review we considered the role of modulation of the immune system as an alternative approach. This is an update of a Cochrane Review previously published in 2009 (Lu 2009).

OBJECTIVES

To assess the effects of pentoxifylline, which has anti-inflammatory effects, in subfertile, premenopausal women for the management of endometriosis.

SEARCH METHODS

For the first publication of this review we searched the following databases (from inception to December 2008) for trials: Cochrane Menstrual Disorders and Subfertility Group Specialised Register, Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library), MEDLINE, EMBASE, CINAHL, and PsycINFO. In addition, all reference lists of included trials were searched and experts in the field were contacted in an attempt to locate trials. This search was rerun to 23 November 2011, for this update.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing pentoxifylline with placebo or no treatment, medical treatment, or surgery in subfertile, premenopausal women were included.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials for inclusion, assessed trial risk of bias, and extracted data using data extraction forms. We contacted study authors for additional information and data. The domains assessed for risk of bias were sequence generation, allocation concealment, blinding, incomplete outcome data, and selective outcome reporting. Peto odds ratios (OR) were used for reporting dichotomous data with 95% confidence intervals (CI), whilst mean differences (MD) were expressed for continuous data. Statistical heterogeneity was assessed using the I(2) statistic.

MAIN RESULTS

Four trials involving 334 participants were included. One RCT [n=34] showed pentoxifylline had no significant effect on reduction in pain (MD -1.60, 95% CI -3.32 to 0.12). There was no evidence of an increase in clinical pregnancy events in the pentoxifylline group compared with placebo (three RCTs [n=67] OR 1.54, 95% CI 0.89 to 266). One RCT studied recurrence of endometriosis [n=88] (OR 0.88,95% CI 0.27 to 2.84). No trials reported the effects of pentoxifylline on the odds of live birth rate per woman, improvement of endometriosis-related symptoms, or adverse events.

AUTHORS' CONCLUSIONS

This review has been updated in 2011. The results of the original review published in 2009 remain unchanged. There is still not enough evidence to support the use of pentoxifylline in the management of premenopausal women with endometriosis in terms of subfertility and relief of pain outcomes.

Pathophysiological role and therapeutic implications of inflammation in diabetic nephropathy

Diabetes mellitus and its complications are becoming one of the most important health problems in the world. Diabetic nephropathy is now the main cause of end-stage renal disease. The mechanisms leading to the development and progression of renal injury are not well known. Therefore, it is very important to find new pathogenic pathways to provide opportunities for early diagnosis and targets for novel treatments. At the present time, we know that activation of innate immunity with development of a chronic low grade inflammatory response is a recognized factor in the pathogenesis of diabetic nephropathy. Numerous experimental and clinical studies have shown the participation of different inflammatory molecules and pathways in the pathophysiology of this complication.

Cytokines in diabetic nephropathy

Diabetic nephropathy (DN), the most common cause of end-stage renal disease (ESRD), is increasingly considered an inflammatory process characterized by leukocyte infiltration at every stage of renal involvement. Cytokines act as pleiotropic polypeptides that regulate inflammatory and immune responses, providing important signals in the pathologic and physiologic processes. Inflammation and activation of the immune system are closely involved in the pathogenesis of diabetes and its microvascular complications. Proinflammatory, Th1, Th2, and Th17 cytokines, as well as TGF-beta, all take part in the development and progression of DN. Gene polymorphism of cytokines and their receptors may have functional variations and can be applied to predict the susceptibility and progression to DN. Improved knowledge on recognizing cytokines as significant pathogenic mediators in DN leaves opens the possibility of new potential therapeutic agents for future clinical treatments.

Pentoxifylline for renoprotection in diabetic nephropathy: the PREDIAN study. Rationale and basal results

STATEMENTS OF THE PROBLEM

Diabetic nephropathy (DN) is the main cause of end-stage renal disease (ESRD). Renin-angiotensin system (RAS) blockade is the standard of care; however, a significant proportion of patients progress to ESRD. Pentoxifylline (PTF) possesses properties suggesting potential renoprotective efficacy. The aim of the Pentoxifylline for Renoprotection in Diabetic Nephropathy (PREDIAN) study is to test the efficacy of PTF addition to RAS blockade on the progression of DN. Here we report the study design and the baseline patient characteristics.

METHODS

This is an investigator-initiated, single-center, prospective, randomized, controlled, clinical trial without any commercial interest, funded by the Spanish Ministry of Science and Innovation. One hundred and sixty-nine type 2 diabetic patients with Stage 3 and 4 chronic kidney disease (CKD) were randomized to a control group (n=87) or an active group (n=82), which will receive PTF (1200 mg/day) for 24 months. The primary outcome measure is the difference in estimated glomerular filtration rate (eGFR) between the groups at the end of the study.

RESULTS

The baseline characteristics of the subjects are as follows: 116 patients (68.6%) with Stage 3 CKD and 53 (31.3%) Stage 4 CKD, age 69±9 years, duration of diabetes 15±3 years, eGFR 37±12 ml/min per 1.73 m(2), albuminuria 1.39±1.16 g/day, blood pressure 142±8/86±8 mmHg. Inflammatory cytokines (tumor necrosis factor-α, interleukin-6, and interleukin-10) and polymorphisms of the coding genes for these molecules are studied.

CONCLUSIONS

The PREDIAN study will provide evidence on the renoprotective benefit of PTF in addition to interventions of proven efficacy (RAS blockade) in DN.

Pentoxifylline attenuates TNF-α protein levels and brain edema following temporary focal cerebral ischemia in rats

Cerebral edema is the most common cause of neurological deterioration and mortality during acute ischemic stroke. Despite the clinical importance of cerebral ischemia, the underlying mechanisms remain poorly understood. Recent studies suggest a role for TNF-α in the brain edema formation. To further investigate whether TNF-α would play a role in brain edema formation, we examined the effects of pentoxifylline (PTX, an inhibitor of TNF-α synthesis) on the brain edema and TNF-α levels in a model of transient focal cerebral ischemia. The right middle cerebral artery (MCA) of rats was occluded for 60 min using the intraluminal filament method. The animals received PTX (60 mg/kg) immediately, 1, 3, or 6h post-ischemic induction. Twenty-four hours after induction of ischemic injury, permeability of the blood-brain barrier (BBB) and brain edema were determined by in situ brain perfusion of Evans Blue (EB) and wet-to-dry weight ratio, respectively. TNF-α protein levels in ischemic cortex were also measured at 1, 4, and 24h after the beginning of an ischemic stroke by using an enzyme-linked immunosorbent assay method. The administration of PTX up to 6h after occlusion of the MCA significantly reduced the brain edema. Moreover, PTX significantly reduced the concentration of TNF-α in ischemic brain cortex up to 4h post-transient focal stroke (P<0.002). Finally, treatment by PTX led to a significant decrease in EB extravasations (P<0.001). Our data demonstrate that PTX administration up to 6h after ischemia can reduce brain edema in a model of transient focal cerebral ischemia. The beneficial effects of PTX may be mediated, at least in part, through a decline in TNF-α production and BBB breakdown.

Metabolic syndrome is a low-grade systemic inflammatory condition

An increase in proinflammatory cytokines, a decrease in endothelial nitric oxide and adiponectin levels and an alteration in hypothalamic peptides and gastrointestinal hormones that regulate satiety, hunger and food intake all occur in metabolic syndrome. Consumption of a diet that is energy dense and rich in saturated and trans-fats by pregnant women and lactating mothers, in childhood and adult life may trigger changes in the hypothalamic and gut peptides and hormones. Such changes modulate immune response and inflammation and lead to alterations in the hypothalamic 'bodyweight/appetite/satiety set point' and result in the initiation and development of the metabolic syndrome. Roux-en-gastric bypass induces weight loss, decreases the levels of cytokines and restores hypothalamic neuropeptides and gut hormones and the hypothalamic bodyweight/appetite/satiety set point to normal. Thus, metabolic syndrome is a low-grade systemic inflammatory condition with its origins in the perinatal period and childhood.

Pentoxifylline versus medical therapies for subfertile women with endometriosis

BACKGROUND

Endometriosis is a chronic, recurring condition that occurs during the reproductive years. It is characterized by endometrial tissue developing outside the uterine cavity. This endometrial tissue development is dependent on estrogen produced primarily by the ovaries and, therefore, traditional management has focused on ovarian suppression. In this review we considered the role of modulation of the immune system as an alternative approach.

OBJECTIVES

To determine the effectiveness and safety of pentoxifylline, which has anti-inflammatory effects, in the management of endometriosis in subfertile, premenopausal women.

SEARCH STRATEGY

We searched the following databases (from inception to December 2008) for trials: Cochrane Menstrual Disorders and Subfertility Group Specialised Register, Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library), MEDLINE, EMBASE, CINAHL, and PsycINFO. In addition, all reference lists of included trials were searched and experts in the field were contacted in an attempt to locate trials.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing pentoxifylline with placebo or no treatment, medical treatment, or surgery in subfertile, premenopausal women were included.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials for inclusion, assessed trial quality, and extracted data using data extraction forms. We contacted study authors for additional information and data. The domains assessed for risk of bias were sequence generation, allocation concealment, blinding, incomplete outcome data, and selective outcome reporting. Odds ratios (OR) were used for reporting dichotomous data with 95% confidence intervals (CI), whilst mean differences (MD) were expressed for continuous data. Statistical heterogeneity was assessed using the I(2) statistic.

MAIN RESULTS

Four trials involving 334 participants were included. Results showed pentoxifylline had no significant effect on reduction in pain (one RCT, MD -1.60, 95% CI -3.32 to 0.12). There was no evidence of an increase in clinical pregnancy events in the pentoxifylline group compared with placebo (three RCTs, OR 1.54, 95% CI 0.89 to 266). For recurrence of endometriosis, one RCT reported an OR of 0.88 (95% CI 0.27 to 2.84). No trials reported the effects of pentoxifylline on the odds of live birth rate per woman, improvement of endometriosis-related symptoms, or adverse events.

AUTHORS' CONCLUSIONS

There is not enough evidence to support the use of pentoxifylline in the management of premenopausal women with endometriosis in terms of subfertility and relief of pain outcomes.

Pretreatment with R(+)-verapamil significantly reduces mortality and cytokine expression in murine model of septic shock

It is well known that cytokines play an important role in the pathogenesis of sepsis and septic shock. There is evidence indicating that the membrane transporter, P-glycoprotein (P-gp), may be involved in the release of cytokines, such as IL-2, IL-4 or IFN-gamma. The aim of this study was to assess the influence of P-gp inhibitor, R(+)-verapamil, on cytokine expression in serum and tissues as well as survival rate of mice with LPS-induced septic shock. These effects were compared with the response to treatment with pentoxifylline, lisofylline, and prednisolone administered alone or after pretreatment with R(+)-verapamil. When given as a single agent, R(+)-verapamil significantly decreased serum levels of TNF-alpha and IFN-gamma and protected mice from endotoxin lethality. Moreover, it decreased up-regulated by LPS TNF-alpha gene expression in the liver and lungs. Given concomitantly with immunomodulatory compounds, it enhanced their beneficial impact on the survival of mice with septic shock. The highest increase in survival rate was observed in combination with pentoxifylline (7% vs. 67%). The most striking differences observed between saline and R(+)-verapamil pretreated animals on combination therapy included down-regulation of TNF-alpha, higher levels of IL-6, and decreased IFN-gamma concentrations. These results suggest that P-gp may be involved in the release of IFN-gamma, and possibly also TNF-alpha, in mice with septic shock. R(+)verapamil improves survival of mice receiving a lethal dose of LPS and significantly potentiates the protective effect of pentoxifylline and prednisolone against LPS-induced lethality, probably as a result of both P-gp inhibition and a synergistic interaction at the gene level.

Pathogenic perspectives for the role of inflammation in diabetic nephropathy

Diabetes and its complications have become a public health problem. One of the most important complications is diabetic nephropathy, which is nowadays the main cause of chronic renal failure. In spite of our greater understanding of this complication, the intimate mechanisms leading to the development and progression of renal injury are not well understood. New perspectives in activated innate immunity and inflammation appear to be relevant factors in the pathogenesis of diabetes. Moreover, different inflammatory molecules, including adipokines, Toll-like receptors, chemokines, adhesion molecules and pro-inflammatory cytokines, may be critical factors in the development of microvascular diabetic complications, including nephropathy. This new pathogenic perspective leads to important therapeutic considerations, with new pathogenic pathways becoming important therapeutic targets that can be translated into clinical treatments for diabetic nephropathy.

Tumor necrosis factor-alpha as a therapeutic target for diabetic nephropathy

Activation of innate immunity with the subsequent development of a chronic low-grade inflammatory response is now recognized as a critical factor in the pathogenesis of diabetes mellitus and diabetic complications, including diabetic nephropathy. In the setting of diabetic nephropathy, there is now evidence of the relevant contribution of pro-inflammatory cytokines, with special participation of tumor necrosis factor-alpha (TNF-alpha). This new pathogenic perspective leads to new therapeutic implications derived from modulation of inflammation and inflammatory cytokines. Experimental studies have shown the beneficial renal actions derived from TNF-alpha inhibition with the use of soluble TNF-alpha receptor fusion proteins, chimeric monoclonal antibodies and pentoxifylline (PTF). Clinical application of this strategy is nowadays limited to PTF administration, which has demonstrated significant beneficial effects in patients with diabetic nephropathy. Overall, these studies indicate that inhibition of TNF-alpha might be an efficacious treatment for renal disease secondary to diabetes mellitus.

The role of MAP kinase phosphatase-1 in the protective mechanism of dexamethasone against endotoxemia

AIMS

We have previously shown that glucocorticoids induce the expression of MAP kinase phosphatase (Mkp)(a)-1 in innate immune cells. Since Mkp-1 is a critical negative regulator of the innate immune response, we hypothesize that Mkp-1 plays a significant role in the anti-inflammatory action of glucocorticoids. The specific aim of the present study is to understand the role of Mkp-1 in the anti-inflammatory function of glucocorticoids.

MAIN METHODS

Wild-type and Mkp-1(-/-) mice were treated with different doses of dexamethasone and then challenged with different doses of lipopolysaccharide (LPS). The survival and blood cytokines were assessed. The effects of dexamethasone on cytokine production in wild-type and Mkp-1(-/-) primary macrophages ex vivo were also examined.

KEY FINDINGS

We found that dexamethasone induced the expression of Mkp-1 in vivo. Dexamethasone treatment completely protected wild-type mice from the mortality caused by a relatively high dose of LPS. However, dexamethasone treatment offered only a partial protection to Mkp-1(-/-) mice. Dexamethasone attenuated TNF-alpha production in both wild-type and Mkp-1(-/-) mice challenged with LPS, although TNF-alpha production in Mkp-1(-/-) mice was significantly more robust than that in wild-type mice. Dexamethasone pretreatment shortened the duration of p38 and JNK activation in LPS-stimulated wild-type macrophages, but had little effect on p38 or JNK activation in similarly treated Mkp-1(-/-) macrophages.

SIGNIFICANCE

Our results indicate that the inhibition of p38 and JNK activities by glucocorticoids is mediated by enhanced Mkp-1 expression. These results demonstrate that dexamethasone exerts its anti-inflammatory effects through both Mkp-1-dependent and Mkp-1-indepent mechanisms.

Corticosteroids in the prevention and treatment of acute respiratory distress syndrome (ARDS) in adults: meta-analysis

OBJECTIVE

To systematically review the efficacy of steroids in the prevention of acute respiratory distress syndrome (ARDS) in critically ill adults, and treatment for established ARDS.

DATA SOURCES

Search of randomised controlled trials (1966-April 2007) of PubMed, Cochrane central register of controlled trials, Cochrane database of systematic reviews, American College of Physicians Journal Club, health technology assessment database, and database of abstracts of reviews of effects.

DATA EXTRACTION

Two investigators independently assessed trials for inclusion and extracted data into standardised forms; differences were resolved by consensus.

DATA SYNTHESIS

Steroid efficacy was assessed through a Bayesian hierarchical model for comparing the odds of developing ARDS and mortality (both expressed as odds ratio with 95% credible interval) and duration of ventilator free days, assessed as mean difference. Bayesian outcome probabilities were calculated as the probability that the odds ratio would be > or =1 or the probability that the mean difference would be > or =0. Nine randomised trials using variable dose and duration of steroids were identified. Preventive steroids (four studies) were associated with a trend to increase both the odds of patients developing ARDS (odds ratio 1.55, 95% credible interval 0.58 to 4.05; P(odds ratio > or =1)=86.6%), and the risk of mortality in those who subsequently developed ARDS (three studies, odds ratio 1.52, 95% credible interval 0.30 to 5.94; P(odds ratio > or =1)=72.8%). Steroid administration after onset of ARDS (five studies) was associated with a trend towards reduction in mortality (odds ratio 0.62, 95% credible interval 0.23 to 1.26; P(odds ratio > or =1)=6.8%). Steroid therapy increased the number of ventilator free days compared with controls (three studies, mean difference 4.05 days, 95% credible interval 0.22 to 8.71; P(mean difference > or =0)=97.9%). Steroids were not associated with increase in risk of infection.

CONCLUSIONS

A definitive role of corticosteroids in the treatment of ARDS in adults is not established. A possibility of reduced mortality and increased ventilator free days with steroids started after the onset of ARDS was suggested. Preventive steroids possibly increase the incidence of ARDS in critically ill adults.

[Changes in diagnostic and therapeutic standards of acute pancreatitis in clinical practice. Epidemiologic analysis of data from a regional center of internal medicine and surgery]

Epidemiological data analysis of a tertiary (regional) medical and surgical center. Diagnostic and therapeutic standards of patients with acute pancreatitis have changed significantly in the last few decades. Progress in laboratory and imaging diagnostics and achievements in experimental research resulted in a significant modification of the guidelines related to the care of pancreatitic patients. The aim was to analyse and compare the data of patients with acute pancreatitis treated in 1996 (period I) and 2004 (period II) at the Departments of Internal Medicine and Surgery, University of Szeged, to evaluate the concordance with international guidelines during medical and surgical treatment.

RESULTS

The authors analysed the clinical data of 126 and 124 patients, respectively, with acute pancreatitis observed during the two periods. An increase in the incidence of biliary acute pancreatitis, more frequent use of antibiotics, a higher frequency of therapeutic endoscopies (papillotomy and biliary stone extraction), the general application of ultrasonography-guided fine needle aspiration and bacterial culturing in cases of suspected infected necrosis, and higher effectiveness in complex surgical and supportive management of infected necrosis cases were detected in period II.

CONCLUSION

Although most of the achievements suggested in international guidelines on medical/endoscopic and surgical treatment of acute pancreatitis have been implemented during the observation period, no significant changes in the morbidity and mortality data of patients were found.

Early switch to pentoxifylline in patients with severe alcoholic hepatitis is inefficient in non-responders to corticosteroids

BACKGROUND/AIMS

In severe alcoholic hepatitis (AH), 40% of patients will obtain no benefit from corticosteroids. Improvement in management of non-responders is warranted and only pentoxifylline can be considered an alternative. A two-step strategy was evaluated consisting of early withdrawal of corticosteroids and a switch to pentoxifylline for 28 additional days in non-responders identified using early change in bilirubin level.

METHODS

One hundred and twenty-one patients with AH were treated prospectively with corticosteroids, and the two-step strategy was proposed to 29 non-responders treated according to a two-step strategy who were compared to 58 matched non-responders treated with corticosteroids only.

RESULTS

Clinical and biological features of the two groups were similar. There was no survival improvement at 2 months in patients treated with the two-step strategy compared to controls: 35.5+/-6.3% vs 31+/-8.6%. After 21 days, biological evolution was similar for prothrombin time (-0.25s vs +0.2s), bilirubin (0.8 mg/dl vs 2.03 mg/dl) and creatinine (+0.16 mg/dl vs -0.7 mg/dl). In multivariate analysis, only age, evolution of bilirubin during the first week, creatinine and DF were associated with 2-month survival.

CONCLUSIONS

Non-responders to corticosteroids do not obtain any benefit from an early switch to pentoxifylline. Thus, the issue of management of non-responders remains unresolved.

Aberrant activation of stress-response pathways leads to TNF-alpha oversecretion in Fanconi anemia

Fanconi anemia (FA), an inherited syndrome that associates bone marrow failure, cancer predisposition, and genetic instability, is characterized by an overproduction of the myelosuppressive cytokine TNF-alpha through unknown mechanisms. We demonstrate here that FANC pathway loss-of-function results in the aberrant activation of 2 major stress-signaling pathways: NF-kappaB and MAPKs. These responses are independent on TNF-alpha expression. On the contrary, inhibition of the MAPK pathways normalizes TNF-alpha oversecretion in FA. Moreover, our data show that the overexpression of the matrix metalloproteinase MMP-7 is the key event directly responsible for the high rate of TNF-alpha shedding and release from the cytoplasmic membrane in FA. TNF-alpha overproduction is, indeed, normalized by MMP-7 inhibition. Finally, MAPK inhibition impacts on MMP-7 overexpression. Evidence is provided of the existence of a linear pathway in which FANC mutations activate MAPK signaling that induces MMP-7 overexpression leading, in fine, to TNF-alpha oversecretion. TNF-alpha may, in turn, sustain or amplify both MAPKs and NF-kappaB activation. Aberrant expression or activity of NF-kappaB and/or MAPKs has been already involved in bone marrow failure and leukemia, and their inhibition offered clinical benefit for patients. In conclusion, our data provide a strong rationale for new clinical trials on FA patients.

Anti-inflammatory functions of glucocorticoid-induced genes

There is a broad consensus that glucocorticoids (GCs) exert anti-inflammatory effects largely by inhibiting the function of nuclear factor kappaB (NFkappaB) and consequently the transcription of pro-inflammatory genes. In contrast, side effects are thought to be largely dependent on GC-induced gene expression. Biochemical and genetic evidence suggests that the positive and negative effects of GCs on transcription can be uncoupled from one another. Hence, novel GC-related drugs that mediate inhibition of NFkappaB but do not activate gene expression are predicted to retain therapeutic effects but cause fewer or less severe side effects. Here, we critically re-examine the evidence in favor of the consensus, binary model of GC action and discuss conflicting evidence, which suggests that anti-inflammatory actions of GCs depend on the induction of anti-inflammatory mediators. We propose an alternative model, in which GCs exert anti-inflammatory effects at both transcriptional and post-transcriptional levels, both by activating and inhibiting expression of target genes. The implications of such a model in the search for safer anti-inflammatory drugs are discussed.

A randomized controlled trial of pentoxifylline for the prevention of post-ERCP pancreatitis

BACKGROUND

Pentoxifylline can ameliorate pancreatitis in animal models because of its anti-tumor necrosis factor properties.

OBJECTIVE

Our purpose was to study the safety and efficacy of pentoxifylline in the prevention of post-ERCP pancreatitis.

DESIGN

Patients due to undergo ERCP for various indications were randomized to receive pentoxifylline 400 mg orally 3 times, beginning the day before ERCP (2 and 10 pm) until the night after the procedure (6 am and 2 and 10 pm) or to receive no preventive medication. Serum amylase values were determined before and 6 and 24 hours after ERCP. Diagnosis and grading of the severity of complications was performed according to consensus criteria.

PATIENTS

One hundred fifty-eight patients received pentoxifylline (group A) and 162 had no medication (group B). The groups were similar in distributions of sex, biliary sphincterotomy, pancreatography, pancreatic duct cannulations, stone extraction, stent placement, and presence of periampullary diverticulum. Group A patients were younger (mean age 63 vs 68 years, P<.05) and biliary colic was a more frequent indication (30 vs 12, P<.05).

RESULTS

Nine (5.6%) patients in group A and 5 (3%) in group B had pancreatitis (2 and 1 severe, respectively; P=.28). Serum amylase values were similar in baseline and 6- and 24-hour samples. Two (1.2%) patients in group A and 7 (4.3%) in group B had hemorrhage.

LIMITATIONS

This was not a double-blind trial.

CONCLUSIONS

In this study pentoxifylline did not protect against post-ERCP pancreatitis or hyperamylasemia.

Enhanced Antitumor Effect of Combined Triptolide and Ionizing Radiation

PURPOSE

The lack of effective treatment for pancreatic cancer results in a very low survival rate. This study explores the enhancement of the therapeutic effect on human pancreatic cancer via the combination of triptolide and ionizing radiation (IR).

EXPERIMENTAL DESIGN

In vitro AsPC-1 human pancreatic cancer cells were treated with triptolide alone, IR alone, or triptolide plus IR. Cell proliferation was analyzed with sulforhodamine B (SRB) method and clonogenic survival; comparison of apoptosis induced by the above treatment was analyzed by annexin V-propidium iodide (PI) staining. Furthermore, the expression of apoptotic pathway intermediates was measured by the assay of caspase activity and Western blot. Mitochondrial transmembrane potential was determined by JC-1 assay. In vivo, AsPC-1 xenografts were treated with 0.25 mg/kg triptolide, 10 Gy IR, or triptolide plus IR. The tumors were measured for volume and weight at the end of the experiment. Tumor tissues were tested for terminal nucleotidyl transferase-mediated nick end labeling (TUNEL) and immunohistochemistry.

RESULTS

The combination of triptolide plus IR reduced cell survival to 21% and enhanced apoptosis, compared with single treatment. In vivo, tumor growth of AsPC-1 xenografts was reduced further in the group treated with triptolide plus IR compared with single treatment. TUNEL and immunohistochemistry of caspase-3 cleavage in tumor tissues indicated that the combination of triptolide plus IR resulted in significantly enhanced apoptosis compared with single treatments.

CONCLUSIONS

Triptolide in combination with ionizing radiation produced synergistic antitumor effects on pancreatic cancer both in vitro and in vivo and seems promising in the combined modality therapy of pancreatic cancer.

Regulation of innate immune response by MAP kinase phosphatase-1

Mitogen-activated protein (MAP) kinase cascades are signal transduction pathways that play pivotal regulatory roles in the biosynthesis of pro-inflammatory cytokines. MAP kinase phosphatase (MKP)-1, an archetypal member of the MKP family, is essential for the dephosphorylation/deactivation of MAP kinases p38 and JNK. Earlier studies conducted using cultured immortalized macrophages provided compelling evidence indicating that MKP-1 deactivates p38 and JNK, thereby limiting pro-inflammatory cytokine biosynthesis in innate immune cells exposed to microbial components. Recent studies employing MKP-1 knockout mice have confirmed the central function of MKP-1 in the feedback control of p38 and JNK activity as well as the crucial physiological function of MKP-1 as a negative regulator of the synthesis of pro-inflammatory cytokines in vivo. MKP-1 was shown to be a major feedback regulator of the innate immune response and to play a critical role in preventing septic shock and multi-organ dysfunction during pathogenic infection. In this review, we will update the studies on the biochemical properties and the regulation of MKP-1, and summarize our understanding on the physiological function of this key phosphatase in the innate immune response.

MAPK phosphatases--regulating the immune response

Mitogen-activated protein kinase (MAPK) phosphatases (MKPs) are protein phosphatases that dephosphorylate both the phosphothreonine and phosphotyrosine residues on activated MAPKs. Removal of the phosphates renders MAPKs inactive, effectively halting their cellular function. In recent years, evidence has emerged that, similar to MAPKs, MKPs are pivotal in the regulation of immune responses. By deactivating MAPKs, MKPs can modulate both innate and adaptive immunity. A number of immunomodulatory agents have been found to influence the expression of MKP1 in particular, highlighting the central role of this phosphatase in immune regulation. This Review discusses the properties, function and regulation of MKPs during immune responses.

Pharmacokinetics of Intranasal and Intratracheal Pentoxifylline in Rabbits

STUDY OBJECTIVE

To evaluate the disposition of pentoxifylline and its metabolite, lisofylline, in New Zealand rabbits after two alternative routes of administration, intranasal and intratracheal.

DESIGN

Pharmacokinetics study in an animal model.

SETTING

University-affiliated animal care facility.

SUBJECTS

Twenty New Zealand white rabbits divided into four groups of five rabbits each: group 1 did not receive study drug (control group), and groups 2, 3, and 4 evaluated intravenous, intranasal, and intratracheal routes of administration, respectively.

INTERVENTION

Each rabbit in groups 2-4 received pentoxifylline as a single 20-mg/kg dose by their respective route of administration.

MEASUREMENTS AND MAIN RESULTS

Blood samples were collected over a 24-hour period and were analyzed by using high-performance liquid chromatography-tandem mass spectrometry. The pharmacokinetic parameters evaluated were area under the concentration-time curve from time zero extrapolated to infinity (AUC(0-infinity)), maximum concentration (Cmax), time to maximum concentration (Tmax), elimination rate constant (k(el)), and half-life (t1/2). Median pentoxifylline pharmacokinetic parameters after intravenous administration were AUC(0-infinity) 5420 ng x hr/ml, Cmax 16,727 ng/ml, Tmax 5 minutes, k(el) 0.036 minute(-1), and t1/2 19 minutes. Median pharmacokinetic parameters after intranasal and intratracheal administration, respectively, were AUC(0-infinity) 4224 and 6824 ng x hr/ml, Cmax 11,181 and 16,758 ng/ml, Tmax 5 and 5 minutes, k(el) 0.028 and 0.032 minute(-1), and t1/2 25 and 22 minutes. The metabolite, lisofylline, displayed a similar disposition after the three different routes of administration.

CONCLUSION

The pharmacokinetic profiles after intranasal and intratracheal administration of pentoxifylline appear similar to those after intravenous administration. These data provide support for development of pentoxifylline intranasal and intratracheal dosage formulations that would be suitable for use in premature neonates.

Beta-adrenergic receptor blockade attenuates the exercise-induced suppression of TNF-alpha in response to lipopolysaccharide in rats

Stressful exercise has been found to reduce the proinflammatory cytokine response to lipopolysaccharide (LPS). In this study, we aimed to determine whether receptor antagonists for corticosterone or catecholamines would increase the LPS-induced tumor necrosis factor-alpha (TNF-alpha) response after exhaustive exercise. Female F344 rats were randomly assigned to one of five groups: control (vehicle), RU-486 (glucocorticoid receptor antagonist, 30 mg/kg)-, propranolol [nonselective beta-adrenergic receptor (AR) blockade, 30 mg/kg]-, atenolol (beta(1)-AR blockade, 30 mg/kg)-, or ICI 118551 (beta(2)-AR blockade, 30 mg/kg)-treated groups. Each antagonist was given intraperitoneally 30 min prior to exercise or control period. Exercised rats ran until exhaustion on a treadmill at gradually increasing speeds, from 10 to 36 m/min at 15% grade. Immediately postexercise or control period all rats were injected with LPS (1 mg/kg, i.v.). Plasma TNF-alpha was reduced by prior exercise to approximately 10% of that of sedentary controls (p < 0.01). Plasma TNF-alpha concentration in exercised RU-486-treated rats was significantly different than that of nonexercised rats (19.2%, p < 0.01) and not different from exercised rats. However, pretreatment of rats with the nonselective beta-AR blocker propranolol almost completely reversed the exercise-induced suppression of plasma TNF-alpha in response to LPS. beta(1)-AR pretreatment almost completely attenuated the exercise-induced suppression of LPS-induced plasma TNF-alpha while beta(2)-antagonism had a partial effect. These results indicate that exercise-induced catecholamines, acting through beta-ARs (especially the beta(1)-AR), are responsible for the exercise-induced suppression of plasma TNF-alpha after LPS administration.

Inflammation and diabetic nephropathy

Diabetic nephropathy has become the main cause of renal failure, but unfortunately the intimate mechanisms leading to the development and progression of renal injury are not yet fully known. Activated innate immunity and inflammation are relevant factors in the pathogenesis of diabetes. Moreover, different inflammatory molecules, including chemokines, adhesion molecules, and proinflammatory cytokines, may be critical factors in the development of microvascular diabetic complications, including nephropathy. This new pathogenic perspective leads to important therapeutic considerations, with new pathogenic pathways becoming important therapeutic targets that can be translated into clinical treatments for diabetic nephropathy.

Beryllium-induced TNF-alpha production is transcription-dependent in chronic beryllium disease

Beryllium (Be)-antigen presentation to Be-specific CD4(+) T cells from the lungs of patients with chronic beryllium disease (CBD) results in T cell proliferation and TNF-alpha secretion. We tested the hypothesis that Be-induced, CBD bronchoalveolar lavage (BAL) T cell, transcription-dependent, TNF-alpha secretion was accompanied by specific transcription factor upregulation. After 6 h of Be stimulation, CBD BAL cells produced a median of 883 pg/ml TNF-alpha (range, 608-1,275 pg/ml) versus 198 pg/ml (range, 116-245 pg/ml) by unstimulated cells. After 12 h CBD BAL cells produced a median of 2,963 pg/ml (range, 99-9,424 pg/ml) TNF-alpha versus 55 pg/ml (range, 0-454) by unstimulated cells. Using real-time RT-PCR, Be-stimulated TNF-alpha production at 6 h was preceded by a 5-fold increase in TNF-alpha pre-mRNA copy number:beta-actin copy number (Be median ratio 0.21; unstimulated median ratio 0.04). The median ratio of mature TNF-alpha mRNA:beta-actin mRNA was upregulated 1.4-fold (Be median ratio 0.17; unstimulated median ratio 0.12). Be exposure in the presence of the transcription inhibitor pentoxifylline (PTX) decreased CBD BAL cell TNF-alpha pre-mRNA levels > 60%, whereas treatment with the mRNA splicing inhibitor 2-aminopurine (2AP) decreased levels 40% relative to Be exposure alone. PTX treatment decreased mature TNF-alpha mRNA levels 50% while 2AP decreased levels > 80%, relative to Be exposure alone. Beryllium exposure specifically upregulated transcription factors AP-1 and NF-kappaB. The data suggest that Be exposure induces transcription-dependent TNF-alpha production, potentially due to upregulation of specific transcription factors.

Immunopathogenesis of cerebral malaria

Malaria is one of the most important global health problems, potentially affecting more than one third of the world's population. Cerebral malaria (CM) is a deadly complication of Plasmodium falciparum infection, yet its pathogenesis remains incompletely understood. In this review, we discuss some of the principal pathogenic events that have been described in murine models of the disease and relate them to the human condition. One of the earliest events in CM pathogenesis appears to be a mild increase in the permeability to protein of the blood-brain barrier. Recent studies have shown a role for CD8+T cells in mediating damage to the microvascular endothelium and this damage can result in the leakage of cytokines, malaria antigens and other potentially harmful molecules across the blood-brain barrier into the cerebral parenchyma. We suggest that this, in turn, leads to the activation of microglia and the activation and apoptosis of astrocytes. The role of hypoxia in the pathogenesis of cerebral malaria is also discussed, with particular reference to the local reduction of oxygen consumption in the brain as a consequence of vascular obstruction, to cytokine-driven changes in glucose metabolism, and to cytopathic hypoxia. Interferon-gamma, a cytokine known to be produced in malaria infection, induces increased expression, by microvascular endothelial cells, of the haem enzyme indoleamine 2,3-dioxygenase, the first enzyme in the kynurenine pathway of tryptophan metabolism. Enhanced indoleamine 2,3-dioxygenase expression leads to increased production of a range of biologically active metabolites that may be part of a tissue protective response. Damage to astrocytes may result in reduced production of the neuroprotectant molecule kynurenic acid, leading to a decrease in its ratio relative to the neuroexcitotoxic molecule quinolinic acid, which might contribute to some of the neurological symptoms of cerebral malaria. Lastly, we discuss the role of other haem enzymes, cyclooxygenase-2, inducible nitric oxide synthase and haem oxygenase-1, as potentially being components of mechanisms that protect host tissue against the effects of cytokine- and leukocyte-mediated stress induced by malaria infection.

Biologics in the treatment of transplant rejection and ischemia/reperfusion injury: new applications for TNFalpha inhibitors?

Tumor necrosis factor (TNF)-alpha inhibitors have proven efficacy in various autoimmune diseases such as Crohn disease, rheumatoid arthritis, psoriasis, and ankylosing spondylitis. Indeed, some TNFalpha inhibitors have already been approved for the management of the inflammatory manifestations associated with Crohn disease and rheumatoid arthritis. These agents are increasingly used for treatment of corticosteroid-resistant graft-versus-host disease after bone marrow transplantation, and case reports have documented their efficacy in treating corticosteroid- and muromonab-resistant rejection after intestinal transplantation. Thus, the potential role of TNFalpha inhibitors in transplantation of other vascularized solid organs is worthy of investigation. Experimental evidence indicates that TNFalpha plays a key role in mediating ischemia/reperfusion (IR) injury after liver, kidney, intestine, heart, lung, and pancreas transplantation. TNFalpha was also identified as a marker cytokine during organ rejection. Single-center studies evaluating the role of TNFalpha inhibitors in kidney transplantation have been initiated but the results are not yet available. TNFalpha is known to be a contributing factor in kidney allograft rejection, and may have value in predicting the onset of steroid-resistant acute rejection after liver transplantation. Experimental and preliminary clinical data have shown that circulating levels of TNFalpha are increased during cardiac graft rejection, and indicate that TNFalpha plays a role in the pathogenesis of acute cardiac allograft rejection. Anti-TNFalpha therapy was shown to prolong cardiac allograft survival when used alone or in combination with other drugs. TNFalpha genotype has been strongly associated with mortality in humans due to acute cell-mediated heart transplant rejection. In addition, there is evidence for a genetic predisposition toward acute rejection after kidney and simultaneous kidney-pancreas transplantation. TNFalpha inhibition has been used successfully as part of an induction therapy for pancreatic islet cell transplantation. Apart from IR injury and acute rejection after lung transplantation, TNFalpha was also found to be involved in the pathoimmunology of obliterative bronchiolitis. In conclusion, a substantial body of experimental evidence and preliminary clinical data suggest that TNFalpha inhibitors may play an important role in solid-organ transplantation, both in the amelioration of IR injury and in the treatment and prevention of acute rejection. Pharmacodynamic monitoring and pharmacogenetic screening may help to identify patients most likely to benefit from TNFalpha blockade. Randomized controlled trials in patients undergoing solid-organ transplantation are needed to further elucidate the clinical value of TNFalpha inhibition.

Surgical management and complex treatment of infected pancreatic necrosis: 18-year experience at a single center

Infected pancreatic necrosis (IPN), the most severe form of acute pancreatitis, is responsible for most cases of pancreatitis-related morbidity and mortality. Since 1986, 220 patients with IPN have been treated. The surgical treatment was performed on average 18.5 days (range, 8-25 days) after the onset of acute pancreatitis and consisted of wide-ranging necrosectomy, combined with widespread drainage and continuous lavage. In 108 of the 220 cases, some other surgical intervention (distal pancreatic resection, splenectomy, total pancreatectomy, cholecystectomy, colon resection, etc.) was also performed. Following surgery, the supportive therapy consisted of immunonutrition (glutamine and arginine supplementation) and modification of cytokine production with pentoxifylline and dexamethasone. Continuous lavage was applied for an average of 44.5 days (range, 21-95 days), with an average of 9.5 L (range, 5-20 L) of saline per day. The bacteriologic findings revealed mainly enteral bacteria, but Candida infection was also frequently detected (21%). Forty-eight patients (22%) had to undergo reoperation. The overall hospital mortality was 7.7% (17 patients died). In our experience, IPN responds well to adequate surgical treatment, continuous, longstanding widespread drainage and lavage, together with supportive therapy consisting of immunonutrition and modification of cytokine production, combined with adequate antibiotic and antifungal medication.

Mechanism of triptolide-induced apoptosis: effect on caspase activation and Bid cleavage and essentiality of the hydroxyl group of triptolide

Triptolide is a compound extracted from the Chinese herb Tripterygium wilfordii Hook. f. Triptolide has potent anticancer activity. However, the mechanisms by which triptolide exerts its anticancer activities remain unclear. To explore the molecular mechanisms involved in the anticancer activity of triptolide, we have examined the effect of triptolide on the growth of pancreatic carcinoma PANC-1 and cervical adenocarcinoma HeLa cells. We found that treatment of both HeLa and PANC-1 cells with triptolide potently suppressed cell growth and induced apoptosis, indicated by nuclear fragmentation and blebbing. In both HeLa and PANC-1 cells, apoptosis induced by triptolide was associated with activation of both caspase-3 and caspase-8, and cleavage of poly(ADP-ribose) polymerase and Bid. Moreover, in HeLa cells, caspase-9 is also significantly activated in response to triptolide. Overexpression of Bcl-2 in HeLa cells substantially attenuated triptolide-induced apoptosis. Interestingly, substitution of the 14-OH of triptolide with an acetyl group abrogated both its anticancer and its antiinflammatory activities. Our studies suggest that triptolide may exert its anticancer effects by initiating apoptosis through both death-receptor- and mitochondria-mediated pathways. Our results indicate that both the apoptosis-promoting and the antiinflammatory activities of triptolide depend on the 14-OH group.

HIV Impairs TNF-α Release in Response to Toll-Like Receptor 4 Stimulation in Human MacrophagesIn Vitro

The molecular mechanisms for increased risk of bacterial pneumonia in HIV+ persons remain incompletely understood. Recognizing the critical role of Toll-like receptor (TLR) signaling in host defense, this study showed that human U937 macrophage stimulation by the TLR4-specific ligand, lipid A (biologically active component of bacterial LPS), promoted TNF-alpha release through extracellular regulated kinase (ERK)1/2 mitogen-activated protein (MAP) kinase phosphorylation. In contrast, HIV+ U1 macrophages had significantly reduced TNF-alpha release (despite preserved TLR4 expression) and reduced ERK1/2 phosphorylation, whereas TNF-alpha release was intact via a TLR4-independent pathway. In HIV+ U1 cells, reduced ERK1/2 phosphorylation was not due to reduced upstream MEK1/2 activation, but was associated with a reciprocal induction of MAP kinase phosphatase-1 (MKP-1). HIV nef protein was sufficient to reduce TNF-alpha release and induce MKP-1 in healthy macrophages. Pharmacologic inhibition of endogenous cellular phosphatases increased ERK1/2 phosphorylation and partially restored TLR4-mediated TNF-alpha release in HIV+ macrophages. Furthermore, targeted gene silencing of MKP-1 partially restored lipid A-mediated TNF-alpha release in HIV+ U1 cells. Similar results were observed using clinically relevant human alveolar macrophages, comparing healthy to asymptomatic HIV+ persons at clinical risk for bacterial pneumonia. Thus, reduced TLR4-mediated TNF-alpha release through altered ERK1/2 regulation by HIV may impair an effective innate immune response to bacterial challenge. Inhibition of cellular phosphatases may serve as a potential therapeutic target in the management of bacterial pneumonia in HIV+ persons.

Effects of the tumour necrosis factor-alpha inhibitors pentoxifylline and thalidomide in short-term experimental oral mucositis in hamsters

Oral mucositis is a frequent side-effect of cancer therapy. A definitive method of prophylaxis or treatment is not yet available. As pentoxifylline (PTX) and thalidomide (TLD) have been shown to inhibit cytokine synthesis, we studied the effects of these cytokine inhibitors in an experimental oral mucositis model. Oral mucositis was induced in Golden hamsters by the administration of 5-fluorouracil (5-FU) followed by mechanical trauma of the cheek pouch. On days 4, 5, 10, 12, 14 and 16, lesions induced by 5-FU were examined macroscopically and microscopically, and the presence and intensity of hyperemia, erythema, edema, inflammatory cell infiltration, hemorrhagic areas, ulcers and abscesses were recorded. Saline (control), PTX (5, 15, 45 mg kg(-1)) or TLD (10, 30, 90 mg kg(-1)) were administered daily and animals were killed on day 10 for macroscopic and histological analysis and assay of myeloperoxidase (MPO) activity. Animals were weighed daily, and total and differential leukocyte counts were performed on peripheral blood. PTX and TLD were found to reduce the macroscopic and histological parameters of oral mucositis and MPO activity. PTX and TLD also reversed peripheral neutrophilia, but only PTX prevented weight loss. The results indicate a protective effect of PTX and TLD, suggesting an important role for tumour necrosis factor-alpha (TNF-alpha) in the pathophysiology of 5-FU induced-oral mucositis in hamsters.

Novel Treatments for Drug-Induced Toxic Epidermal Necrolysis (Lyell’s Syndrome)

Drug-induced toxic epidermal necrolysis (TEN) is a life-threatening disease characterized by extensive destruction of the epidermis. It apparently results from the formation of specific toxic drug metabolites by the keratinocytes. The mortality rate which averages 25-30% is mainly due to secondary septicemia, and to ionic and metabolic disturbances following loss of epidermal integrity. Apoptosis is the likely mechanism leading to massive keratinocyte death in TEN. Dysregulations in the tumor necrosis factor-alpha (TNF-alpha) pathway, CD95 system (Fas ligand, CD95L; Fas receptor, CD95R) and calcium homeostasis in the epidermis are involved in this apoptotic process. An active role has also been ascribed to T lymphocytes, macrophages and factor XIIIa-positive dermal dendrocytes. Despite progress, treatment of TEN remains controversial. In the past, systemic glucocorticoids were used in order to target the inflammatory reaction in TEN. However, there was no evidence for improvement of the healing process, while corticosteroids worsened the prognosis by increasing the risk of septicemia. Only a few cases have been treated with other drugs including cyclophosphamide, pentoxyfilline, thalidomide, anti-TNF-alpha antibodies and cyclosporin A. In the recent past, some TEN patients were treated with intravenous human immunoglobulins (IVIG). The rationale for such a treatment was to block the CD95 system on keratinocytes. The early promising clinical results of IVIG treatment in TEN were subsequently challenged. This review compares the effectiveness and drawbacks of the major drugs presently used in TEN treatment. Some future prospects in TEN management are also discussed.

Resistance to cytotoxic chemotherapy is induced by NK cells in non-Hodgkin's Lymphoma Cells

It is known that B lymphoma cells are sensitive to cytotoxic chemotherapy, but primary or secondary chemoresistance frequently occurs and is the major cause of death in these patients. However, the mechanisms by which lymphoma cells acquire resistance to cytotoxic drugs are not fully understood. Recently, it was reported that B cells secrete immunoglobulin and produce cytokines after interacting with NK cells, thus indicating the importance of NK/B interactions. In this study, we investigated the mechanism of resistance to cytotoxic chemotherapy induced in cocultures of NK cells and Raji cells. Normally, Raji cells are doxorubicin-sensitive, but Raji cells cocultured with NK cells become doxorubicin-resistant. In addition, we detected the upregulation of CD69 and CD70 on Raji cells cocultured with NK cells, suggesting that Raji cells are activated by NK cells. We also found that the resistance of Raji cells to doxorubicin increased when they had been treated with NK cell coculture supernatant. Furthermore, boiled culture supernatant did not inhibit doxorubicin-mediated cell death, indicating that soluble factors are involved. Finally, we confirmed that NK cells produce TNF alpha, and that doxorubicin-sensitive Raji cells become doxorubicin-resistant after TNF alpha treatment. Taken together, these results suggest that B lymphoma cell resistance to doxorubicin-mediated cell death is induced by coculture with NK cells, because of TNF alpha secretion.

The role of the AU-rich elements of mRNAs in controlling translation

Adenosine- and uridine-rich elements (AREs) located in 3'-untranslated regions are the best-known determinants of RNA instability. These elements have also been shown to control translation in certain mRNAs, including mRNAs for prominent pro-inflammatory and tumor growth-related proteins, and physiological anti-inflammatory processes that target ARE-controlled translation of mRNAs coding for pro-inflammatory proteins have been described. A major research effort is now being made to understand the mechanisms by which the translation of these mRNAs is controlled and the signalling pathways involved. This review focuses on the role of ARE-containing gene translation in inflammation, and the disease models that have improved our understanding of ARE-mediated translational control.

The function of mitogen-activated protein kinase phosphatase-1 in peptidoglycan-stimulated macrophages

Mitogen-activated protein (MAP) kinases play a pivotal role in the macrophages in the production of proinflammatory cytokines triggered by lipopolysaccharides. However, their function in the responses of macrophages to Gram-positive bacteria is poorly understood. Even less is known about the attenuation of MAP kinase signaling in macrophages exposed to Gram-positive bacteria. In the present study, we have investigated the regulation of MAP kinases and the role of MAP kinase phosphatase (MKP)-1 in the production of pro-inflammatory cytokines using murine RAW264.7 and primary peritoneal macrophages after peptidoglycan stimulation. Treatment of macrophages with peptidoglycan resulted in a transient activation of JNK, p38, and extracellular signal-regulated kinase. Most interestingly, MKP-1 expression was potently induced by peptidoglycan, and this induction was concurrent with MAP kinase dephosphorylation. Triptolide, a diterpenoid triepoxide, potently blocked the induction of MKP-1 by peptidoglycan and prolonged the activation of JNK and p38. Overexpression of MKP-1 substantially attenuated the production of tumor necrosis factor (TNF)-alpha induced by peptidoglycan, whereas knockdown of MKP-1 by small interfering RNA substantially increased the production of both TNF-alpha and interleukin-1 beta. Finally, we found that in primary murine peritoneal macrophages, MKP-1 induction following peptidoglycan stimulation also coincided with inactivation of JNK and p38. Blockade of MKP-1 induction resulted in a sustained activation of both JNK and p38 in primary macrophages. Our results reveal that MKP-1 critically regulates the expression of TNF-alpha and interleukin-1 beta in RAW264.7 cells and further suggest a central role for this phosphatase in controlling the inflammatory responses of primary macrophages to Gram-positive bacterial infection.

Polymorphism of immunomodulatory cytokine genes: implications in acute renal failure

Experimental studies have incriminated cytokines and other immunoregulatory molecules as important mediators of tissue injury in acute renal failure (ARF). The relative importance of genetic factors, e.g. polymorphisms involving cytokine genes, in influencing susceptibility to and severity of ARF is unknown. This review summarizes the existing experimental and clinical studies supporting the role of inflammation in ARF, and critically examines human studies that have examined polymorphism of two critical cytokine genes, tumor necrosis factor-alpha and interleukin-10, as potential determinants of susceptibility to and severity of acute infectious and inflammatory diseases. Conclusions are drawn on the application of genetic epidemiology to the field of ARF and the rationale for further research on the role of genetic markers in ARF.