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

Inhibition of glucocorticoid receptor-mediated transcriptional activation by p38 mitogen-activated protein (MAP) kinase

Tumor necrosis factor (TNF) promotes certain immune and inflammatory responses, whereas glucocorticoids exert immunosuppressive and anti-inflammatory actions. We show that TNF treatment produced a modest inhibition of glucocorticoid receptor (GR)-mediated transcriptional activation of a mouse mammary tumor virus (MMTV) promoter-driven luciferase construct in HeLa cells. The mitogen-activated protein (MAP) kinases, p38 and c-Jun N-terminal kinase (JNK), are important mediators of target gene activation by TNF, and JNK activation was earlier shown to inhibit GR-mediated transcriptional activation by direct phosphorylation of GR at Ser-246. Transfection of HeLa cells with MKK6b(E), a constitutively active specific upstream activator of p38, led to a potent inhibition of GR activation of the MMTV promoter-driven luciferase construct. A similar inhibition of activation of the MMTV promoter-driven luciferase construct was seen in HeLa cells transfected with MKK7(D), a constitutively functional activator of JNK. Data from "domain swap" experiments using GR chimeras indicated that the main target of the p38-mediated (but not JNK-mediated) inhibition is the ligand-binding domain of GR (spanning amino acids 525-795), whereas the constitutively active N-terminal AF-1 region (spanning amino acids 106-237) is dispensable for the inhibitory effect of p38. We also demonstrate that activated p38 targets the GR ligand-binding domain indirectly. Suppression of GR function by activated p38 and JNK MAP kinases may be physiologically important as a mechanism of resistance to glucocorticoids seen in many patients with chronic inflammatory conditions.

cAMP targeting of p38 MAP kinase inhibits thrombin-induced NF-kappaB activation and ICAM-1 expression in endothelial cells

We investigated the mechanisms by which elevated intracellular cAMP concentration inhibits the thrombin-induced ICAM-1 expression in endothelial cells. Exposure of human umbilical vein endothelial cells to forskolin or dibutyryl cAMP, which increase intracellular cAMP by separate mechanisms, inhibited the thrombin-induced ICAM-1 expression. This effect of cAMP was secondary to inhibition of NF-kappaB activity, the key regulator of thrombin-induced ICAM-1 expression in endothelial cells. The action of cAMP occurred downstream of IkappaBalpha degradation and was independent of NF-kappaB binding to the ICAM-1 promoter. We observed that cAMP interfered with thrombin-induced phosphorylation of NF-kappaB p65 (RelA) subunit, a crucial event promoting the activation of the DNA-bound NF-kappaB. Because p38 MAPK can induce transcriptional activity of RelA/p65 without altering the DNA binding function of NF-kappaB, we addressed the possibility that cAMP antagonizes thrombin-induced NF-kappaB activity and ICAM-1 expression by preventing the activation of p38 MAPK. We observed that treating cells with forskolin blocked the activation of p38 MAPK, and inhibition of p38 MAPK interfered with phosphorylation of RelA/p65 induced by thrombin. Our data demonstrate that increased intracellular cAMP concentration in endothelial cells prevents thrombin-induced ICAM-1 expression by inhibiting p38 MAPK activation, which in turn prevents phosphorylation of RelA/p65 and transcriptional activity of the bound NF-kappaB.

IgG1 antimycobacterial antibodies can reverse the inhibitory effect of pentoxifylline on tumour necrosis factor alpha (TNF-alpha) secreted by mycobacterial antigen-stimulated adherent cells

Chronic inflammation associated with cachexia, weight loss, fever and arthralgia is the hallmark of advanced mycobacterial diseases. These symptoms are attributed to the chronic stimulation of tumour necrosis factor (TNF)-alpha. Mycobacterial components directly stimulate adherent cells to secrete TNF-alpha. We have shown recently that IgG1 antimycobacterial antibodies play a role in augmenting TNF-alpha in purified protein derivative (PPD)-stimulated adherent cells from non-BCG-vaccinated donors. We now show that IgG1 antibodies can also augment TNF-alpha expression in stimulated adherent cells obtained from BCG-vaccinated donors and this augmentation is not linked to interleukin (IL)-10 secretion. In addition IgG1 antimycobacterial antibodies can reverse the effect of TNF-alpha blockers such as pentoxifylline and thalidomide. These studies therefore have clinical implications for anti-inflammatory drug treatments which are used increasingly to alleviate symptoms associated with chronic inflammation.

The Effects of Local Pentoxifylline and Propentofylline Treatment on Formalin-Induced Pain and Tumor Necrosis Factor-?? Messenger RNA Levels in the Inflamed Tissue of the Rat Paw

We sought to determine whether local administration of pentoxifylline (PTF) or propentofylline (PPTF), which hinders cytokine production, influences pain threshold and formalin-induced pain behavior in rats or the level of tumor necrosis factor-alpha (TNF-alpha) messenger RNA (mRNA) concentrations in the inflamed paw tissue. PTF (0.5, 1, or 2 mg) and PPTF (1 or 2 mg) injected intraplantarly (i.pl.) had no significant effect on pain threshold. Injection of 0.1 mL of a 12% formalin solution subcutaneously into the dorsal surface of the left hindpaw induced pain behavior (47.6 +/- 4.6 incidents per 5 min), and PTF injected at doses of 1 and 2 mg/100 microL i.pl. before (but not after) formalin was effective in antagonizing (33.6 +/- 2.5 and 23.6 +/- 3.4 incidents per 5 min, respectively) formalin-induced pain behavior. A similar antagonistic effect was observed after PPTF treatment at a dose of 2 mg/100 microL; however, in contrast to PTF, at a later time point (85-90 min) after the formalin challenge, this effect was independent of the scheme of PPTF administration, before or after formalin. The effect of PTF on formalin-induced pain behavior did not parallel paw volume as measured by plethysmometer; however, PTF per se significantly increased the paw volume. Formalin injection significantly increased the TNF-alpha mRNA level in the inflamed tissue of the rat hind paw (150%). PTF administered before, but not after, formalin significantly antagonized (by approximately 40%) the observed increase in the level of TNF-alpha mRNA. Our study demonstrates and provides biochemical evidence that preemptive inhibition of proinflammatory cytokine synthesis by the use of PTF and PPTF, phosphodiesterase, and glial activation inhibitors is useful in antagonizing hyperalgesia in formalin-induced pain. Moreover, local administration of PTF may be a valuable approach to the treatment of inflammatory pain.

IMPLICATIONS

This study demonstrates and provides biochemical evidence that preemptive inhibition of proinflammatory cytokine synthesis by local administration of pentoxifylline and propentofylline is useful in antagonizing hyperalgesia in formalin-induced pain. Moreover, local administration of pentoxifylline could be regarded as a valid approach to the treatment of inflammatory pain.

Rapid downregulation of adipose tissue lipoprotein lipase activity on food deprivation: evidence that TNF-alpha is involved

When food was removed from young rats in the early morning, adipose tissue tumor necrosis factor (TNF)-alpha activity increased 50% and lipoprotein lipase (LPL) activity decreased 70% in 6 h. There was a strong negative correlation between the TNF-alpha and LPL activities. Exogenous TNF-alpha further decreased LPL activity. Pentoxifylline, known to decrease production of TNF-alpha, had no effect on LPL activity in fed rats but almost abolished the rise of TNF-alpha and the decrease of LPL activity in rats deprived of food. The specific activity of LPL decreased from 0.92 mU/ng in fed rats to 0.35 and 0.24 mU/ng in rats deprived of food given saline or TNF-alpha, indicating a shift in the LPL molecules toward an inactive state. Lipopolysaccharide increased adipose tissue TNF-alpha and decreased LPL activity. Both of these effects were strongly impeded by pretreatment of the rats with pentoxifylline, or dexamethasone. Pretreatment of the rats with actinomycin D virtually abolished the response of LPL activity to food deprivation or exogenous TNF-alpha. We conclude that food deprivation, like lipopolysaccharide, signals via TNF-alpha to a gene whose product causes a rapid shift of newly synthesized LPL molecules toward an inactive form and thereby shuts down extraction of lipoprotein triglycerides by the adipose tissue.

Extrinsic allergic alveolitis: inhibitory effects of pentoxifylline on cytokine production by alveolar macrophages

BACKGROUND

Pentoxifylline is a well-established drug with hemorheologic properties. Various evidence suggests an additional therapeutic potential in regard to inflammation and immunomodulation. Extrinsic allergic alveolitis (EAA) is a granulomatous disease that is driven by T-cell and alveolar macrophage (AM)-derived cytokines.

OBJECTIVE

To investigate the effects of pentoxifylline on the production of tumor necrosis factor (TNF) alpha, interleukin (IL) 1beta, IL-6, IL-8, IL-10, and the soluble TNF receptors (sTNFR1 and sTNFR2) from AMs in EAA compared with dexamethasone.

METHODS

The AMs from 9 patients with EAA were cultured for 24 hours with RPMI medium alone or lipopolysaccharide (LPS) (100 ng/mL) and with pentoxifylline at concentrations of 0.01, 0.1, and 1 mmol/L or 0.1-mmol/L dexamethasone. Cytokines in the culture supernatants were analyzed by enzyme-linked immunosorbent assay.

RESULTS

Pentoxifylline induced a dose-dependent suppression of spontaneous TNF-alpha and IL-10 release from AMs in EAA. The spontaneous production of other cytokines was unaffected by pentoxifylline at all tested concentrations. Dexamethasone inhibited significantly only the spontaneous release of TNF-alpha. Pentoxifylline and dexamethasone also inhibited the LPS-stimulated production of all cytokines except IL-1beta and sTNFR1.

CONCLUSION

Our results may be the basis for clinical trials to evaluate the role of pentoxifylline as an immunotherapeutic agent in the treatment of EAA.

Inhibition of cytokine release from alveolar macrophages in pulmonary sarcoidosis by pentoxifylline: comparison with dexamethasone

STUDY OBJECTIVES

Pentoxifylline (POF) has been shown to suppress the cytokine production from lipopolysaccharide (LPS)-stimulated monocytes/alveolar macrophages (AMs). Sarcoidosis is a granulomatous disease that is driven by the action of tumor necrosis factor (TNF)-alpha and other proinflammatory cytokines. In this study, we aimed to investigate the effects of POF on the production of TNF-alpha, interleukin (IL)-1 beta, IL-6, IL-8, IL-10, and the soluble TNF receptors (sTNFRs) 1 and 2 from AMs in sarcoidosis, and we also compared them with those of dexamethasone (DEX).

METHODS

AMs from 14 patients with sarcoidosis were cultured for 24 h with RPMI medium alone or with LPS (100 ng/mL), and with POF at concentrations of 0.01, 0.1, and 1 mmol/L, or with 0.1 mmol/L DEX. Cytokines in the culture supernatants were analyzed by enzyme-linked immunosorbent assay.

RESULTS

The results showed that POF induced a dose-dependent suppression of the spontaneous TNF-alpha release from AMs in sarcoidosis (p < 0.001), and that the spontaneous release of the other cytokines was unaffected by POF at all tested concentrations, but a trend for the inhibition of IL-10 production was found (p = 0.092). DEX inhibited the spontaneous release of TNF-alpha (p < 0.001), sTNFR2 (p < 0.05), IL-1 beta (p < 0.05), and IL-10 (p < 0.01). POF also suppressed the LPS-stimulated production of these cytokines except for that of sTNFR1. Similar to POF, DEX inhibited the LPS-stimulated production of these cytokines, but not that of sTNFR1 and IL-1 beta.

CONCLUSIONS

Compared with DEX, POF may improve therapeutic regimens in patients with sarcoidosis either by sparing or by replacing corticosteroids. However, the precise clinical value of POF in the treatment of sarcoidosis and other lung diseases will have to be determined in further clinical trials.

Antibiotic cyclic AMP signaling by "primed" leukocytes confers anti-inflammatory cytoprotection

The mechanism underlying anti-inflammatory effects of macrolide antibiotics remains uncertain. In this study, we first show the evidences concerning the possible link between leukocytic cyclic adenosine monophosphate (cAMP) signaling and the mechanism of anti-inflammatory, cytoprotective actions of macrolides. The clinical range of macrolides (i.e., erythromycin, roxithromycin, and clarithromycin) preferentially inhibited nuclear factor-kappaB activation mediated by reactive oxygen intermediates, inducing cAMP-dependent signaling [i.e., cAMP and cAMP-responsive element-binding protein (CREB)] by "primed" but not "resting" leukocytes. In this context, cAMP/CREB inhibition with adenosine 3':5'-cyclic monophosphothioate, rp-isomer (rp-cAMPs) and CREB decoy oligonucleotides reduced the anti-inflammatory actions of macrolides. These results thus indicate that macrolide-induced cAMP/CREB signaling, selectively by primed leukocytes, plays a major role in the mechanism of anti-inflammatory actions of macrolides.

Pentoxifylline decreases tumor necrosis factor and interleukin-1 during high tidal volume

Tumor necrosis factor-alpha (TNF-alpha) is one of the most important proinflammatory cytokines which plays a central role in host defense and in the acute inflammatory response related to tissue injury. The major source of TNF-alpha are immune cells such as neutrophils and macrophages. We tested the hypothesis that pentoxifylline, a methylxanthine derivative, down-regulates proinflammatory cytokine expression during acute lung injury in rats. Male Wistar rats weighing 250 to 450 g were anesthetized ip with 50 mg/kg sodium thiopental and randomly divided into three groups: group 1 (N = 7): tidal volume (V T) = 7 ml/kg, respiratory rate (RR) = 50 breaths/min and normal saline infusion; group 2 (N = 7): V T = 42 ml/kg, RR = 9 breaths/min and normal saline infusion; group 3 (N = 7): V T = 42 ml/kg, RR = 9 breaths/min and pentoxifylline infusion. The animals were ventilated with an inspired oxygen fraction of 1.0, a positive end-expiratory pressure of 3 cmH2O, and normal saline or pentoxifylline injected into the left femoral vein. The mRNA of TNF-alpha rapidly increased in the lung tissue within 180 min of ventilation with a higher V T with normal saline infusion. The concentrations of inflammatory mediators were decreased in plasma and bronchoalveolar lavage (BAL) in the presence of higher V T with pentoxifylline infusion (TNF-alpha: plasma, 102.2+/-90.9 and BAL, 118.2+/-82.1; IL-1 : plasma, 45.2+/-42.7 and BAL, 50.2+/-34.9, P < 0.05). We conclude that TNF-alpha produced by neutrophil influx may function as an alert signal in host defense to induce production of other inflammatory mediators.

Anti-TNF-alpha therapies: the next generation

The functioning of the immune system is finely balanced by the activities of pro-inflammatory and anti-inflammatory mediators or cytokines. Unregulated activities of these mediators can lead to the development of serious inflammatory diseases. In particular, enhanced tumour-necrosis factor-alpha (TNF-alpha) synthesis is associated with the development of rheumatoid arthritis, psoriatic arthritis and inflammatory bowel disease. Inhibiting TNF-alpha activities in these diseases has been remarkably successful. However, the current injectable protein therapies have associated risks and limitations. An oral, small molecule that regulates TNF-alpha biology could either replace the injectables or provide better disease control when used alone or in conjunction with existing therapies. In this review, we discuss briefly the present understanding of TNF-alpha-mediated biology and the current injectable therapies in clinical use, and focus on some of the new therapeutic approaches with oral, small-molecule inhibitors.

Effects of pentoxifylline administration on urinary N-acetyl-beta-glucosaminidase excretion in type 2 diabetic patients: a short-term, prospective, randomized study

BACKGROUND

Tubulointerstitial injury is a major feature of diabetic nephropathy and an important predictor of renal dysfunction. In 45 patients with type 2 diabetes mellitus (DM), we prospectively analyzed urinary excretion of N-acetyl-beta-glucosaminidase (NAG), a marker of tubular renal damage; the potential relationship with urinary protein excretion; and effects of pentoxifylline (PTF) administration.

METHODS

Forty-five patients with type 2 DM initially were compared with 15 healthy controls matched for age and sex. After randomization, PTF (1,200 mg/d) was administered for 4 months to 30 patients and results were compared with data from a control group (n = 15).

RESULTS

Proteinuria and urinary NAG excretion were significantly greater in patients with DM with respect to healthy controls. Before PTF administration, baseline parameters were similar in both groups of patients with DM. At the end of the study, urinary protein excretion and NAG-creatinine ratios decreased in the active group from 920 +/- 522 mg/d and 14.3 +/- 16.9 U/g to 803 +/- 523 mg/d (P < 0.001) and 10.5 +/- 9.3 U/g (P < 0.05), respectively. Conversely, proteinuria and urinary NAG excretion did not change in the control group. Regression analysis showed that urinary NAG excretion was significantly associated with duration of DM (r = 0.61; P < 0.001) and proteinuria (r = 0.51; P < 0.001).

CONCLUSION

Urinary NAG excretion is elevated in patients with type 2 DM compared with healthy individuals and increases as nephropathy progresses. PTF administration is effective in reducing proteinuria and urinary NAG excretion in these patients. These findings suggest that PTF may have beneficial effects on tubulointerstitial damage in diabetic kidney disease.

Is obesity an inflammatory disease?

BACKGROUND

Most obese individuals have elevated concentrations of interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha), markers of inflammation closely associated with diabetes, hypertension, and stroke.

HYPOTHESIS

Obesity is a low-grade inflammatory disease, and Roux-en-Y gastric bypass (RYGB) reduces biochemical markers of inflammation and modifies gene expression in hypothalamic food intake/energy-related nuclei and subcutaneous abdominal fat (SAF).

METHODS

Obesity was induced in 24 3-week-old Sprague Dawley pups fed a high-energy diet (HED). Three groups (n = 8/group) were studied: RYGB, sham-operated pair-fed, and sham-operated ad libitum HED. Controls were nonobese rats fed chow (n = 6). Rats were killed 10 days after operation, and blood was collected to measure corticosterone and SAF and mesenteric fat to measure IL-6, TNF-alpha, and corticosterone. Total mRNA from arcuate nucleus and SAF purified for gene expression profiling. Data were analyzed with analysis of variance, Mann-Whitney test, and t test.

RESULTS

Before operation, the body weight of the obese groups was 493 +/- 7 g and control = 394 +/- 12g. The 10-day postoperative weight was RYGB = 417 +/- 21 g, pair-fed = 436 +/- 14 g, and ad libitum HED = 484 +/- 15 g. Mesenteric and SAF weight decreased in RYGB. Mesenteric/SAF ratio of IL-6, TNF-alpha, corticosterone, and gene profiling showed decrease of inflammation after RYGB.

CONCLUSIONS

Gastric bypass reduces biochemical markers of inflammation, suggesting that obesity is an inflammatory condition.

Post-transcriptional regulation of gene expression by mitogen-activated protein kinase p38

The mitogen-activated protein kinase p38 pathway was originally identified as a signalling cascade activated by pro-inflammatory stimuli and cellular stresses, and playing a critical role in the translational regulation of pro-inflammatory cytokine synthesis. In almost a decade since this discovery, a great deal has been learned about the role of the p38 pathway in the post-transcriptional regulation of pro-inflammatory gene expression. However, important questions remain to be answered concerning the specificity and mechanism or mechanisms of action of p38. This review describes recent progress and remaining puzzles in the field of post-transcriptional regulation by p38.

Pentoxifyllin attenuates the systemic inflammatory response induced during isolated limb perfusion with recombinant human tumor necrosis factor-alpha and melphalan

BACKGROUND

Isolated limb perfusion (ILP) with recombinant human tumor necrosis factor-alpha (rhTNF-alpha) and melphalan harbors the risk of septic shock-like syndrome. Pentoxifyllin (PTX) produced a beneficial effect on cytokine response and survival in animal experiments of septic shock, and we were interested to explore its effect during TNF-ILP in humans.

METHODS

Eighteen consecutive patients underwent TNF-ILP and received PTX (30 mg/kg/day), whereas another 13 consecutive patients did not. PTX was given systemically after the limb extracorporeal circulation was started. Cardiac index, systemic vascular resistance (SVR), and pulmonary vascular resistance were recorded via a Swan-Ganz catheter. Blood levels of TNF-alpha, interleukin-6, procalcitonin, and lipopolysaccharide-binding protein were determined before, during, and after ILP.

RESULTS

After reperfusion, systemic levels of TNF-alpha were significantly less increased in the PTX group (peak, 2.8 vs. 1.3 ng/mL; P <.05), as were interleukin-6 values (peak, 68 vs. 22 pg/mL; P <.02) and lipopolysaccharide-binding protein plasma levels (peak, 215 vs. 105 micro g/mL; P <.03). Differences in cardiac index, SVR, and mean arterial blood pressure were not significantly different. Norepinephrine or dobutamine to maintain SVR was less required in the PTX group.

CONCLUSIONS

PTX attenuates systemic cytokine production and influences components of the systemic inflammatory response after TNF-ILP. PTX may play a beneficial role in the management of septic shock-like syndrome, particularly in patients with leakage from the ILP circuit.

Immunomodulatory effects of quinolones

We review data on the in-vitro, ex-vivo, in-vivo, and clinical effects of fluoroquinolones on the synthesis of cytokines and their mechanisms of immunomodulation. In general, most fluoroquinolone derivatives superinduce in-vitro interleukin 2 synthesis but inhibit synthesis of interleukin 1 and tumour necrosis factor (TNF)alpha; furthermore, they enhance significantly the synthesis of colony-stimulating factors (CSF). Fluoroquinolones affect in-vivo cellular and humoral immunity by attenuating cytokine responses. Interleukins 10 and 12 have an important role in the functional differentiation of immunocompetent cells and trigger the initiation of the acquired immune response. In addition, certain fluoroquinolones were seen to enhance haematopoiesis by increasing the concentrations of CSF in the lung as well as in the bone marrow and shaft. Those fluoroquinolones exerting significant effects on haematopoiesis were those with a cyclopropyl moiety at position N1 of their quinolone core structure. Mechanisms that could explain the various immunomodulatory effects of fluoroquinolones include: (1) an effect on intracellular cyclic adenosine-3',5'-monophosphate and phosphodiesterases; (2) an effect on transcription factors such as nuclear factor (NF)kappaB, activator protein 1, NF-interleukin-6 and nuclear factor of activated T cells; and (3) a triggering effect on the eukaryotic equivalent of bacterial SOS response with its ensuing intracellular events. Further studies are required, especially in the clinical setting to exploit fully the potential of the immunomodulatory effect of fluoroquinolones during, for example, immunosuppression, chronic airway inflammatory diseases, and sinusitis.

Endogenous versus exogenous glucocorticoid responses to experimental bacterial sepsis

Although lack of adrenals dramatically reduces resistance against sepsis generally, the value of glucocorticoid levels above those normally produced by stress remains controversial. An early and long-held concept is that glucocorticoid protection against lipopolysaccharides in animal models is important. Supporting this concept, C3H/HeJ mice, lacking Toll-like receptor-4 (TLR-4), and consequently, endotoxin hyporesponsive, have recently been shown to be resistant to glucocorticoid protection against live Escherichia coli. Effective antibiotic intervention, as an additional parameter and with concomitant administration of glucocorticoid, not only allows for expected antibiotic protection but also for glucocorticoid protection against E. coli or Staphylococcus aureus of mice sensitized to tumor necrosis factor alpha, regardless of the status of the TLR-4 receptor. TLRs, including but not limited to TLR-2, may be involved in glucocorticoid protective efficacy against Gram-positive and Gram-negative sepsis. Overlapping and possibly endotoxin-independent signaling may become important considerations.

The cytokine network in sarcoidosis and its clinical relevance

In recent years, analysis of the cytokine network has substantially improved our knowledge of the immunopathogenesis of sarcoidosis. There is increasing evidence from clinical immunology that analysis of the cytokine network may be helpful for clinicians to assess the extent and activity of sarcoid inflammation. Genetic polymorphisms may contribute to interindividual differences in the regulation of cytokine release. Thus, disease phenotype-associated haplotypes should exist and their analysis might disclose risk profiles of individual patients. Furthermore, serological assessment of cytokines or soluble cytokine receptors may become suitable parameters in clinical practice to detect an ongoing inflammation in chronic sarcoidosis.

Restraint of proinflammatory cytokine biosynthesis by mitogen-activated protein kinase phosphatase-1 in lipopolysaccharide-stimulated macrophages

Exposure of macrophages to LPS elicits the production of proinflammatory cytokines, such as TNF-alpha, through complex signaling mechanisms. Mitogen-activated protein (MAP) kinases play a critical role in this process. In the present study, we have addressed the role of MAP kinase phosphatase-1 (MKP-1) in regulating proinflammatory cytokine production using RAW264.7 macrophages. Analysis of MAP kinase activity revealed a transient activation of c-Jun N-terminal kinase (JNK) and p38 after LPS stimulation. Interestingly, MKP-1 was induced concurrently with the inactivation of JNK and p38, whereas blocking MKP-1 induction by triptolide prevented this inactivation. Ectopic expression of MKP-1 accelerated JNK and p38 inactivation and substantially inhibited the production of TNF-alpha and IL-6. Induction of MKP-1 by LPS was found to be extracellular signal-regulated kinase dependent and involved enhanced gene expression and increased protein stability. Finally, MKP-1 expression was also induced by glucocorticoids as well as cholera toxin B subunit, an agent capable of preventing autoimmune diseases in animal models. These findings highlight MKP-1 as a critical negative regulator of the macrophage inflammatory response, underscoring its premise as a potential target for developing novel anti-inflammatory drugs.

Pro-inflammatory effects of cholera toxin: role of tumor necrosis factor alpha

Cholera toxin has been traditionally described as the one that does not induce inflammation. It has, however, potent adjuvant and immuno-modulatory activities. Since the adjuvanticity of other compounds is linked to their capacity to induce inflammation, in the present study the pro-inflammatory activity of cholera toxin was investigated. We studied this activity in the following rat models of inflammation: paw edema and neutrophil migration into the peritoneal cavity, and evaluated cholera toxin's effect on tumor necrosis factor alpha (TNF-alpha) production by mouse macrophages. We, also, explored the effects of dexamethasone (DEXA) and of two inhibitors of TNF-alpha production, thalidomide (TAL) and pentoxifylline, on paw swelling. Cholera toxin-induced significant and dose-dependent paw edema, which peaked 48 h after toxin challenge (Cholera toxin(2.5 microg): 2.39 +/- 0.22 ml). Cholera toxin B subunit did not show edematogenic activity. DEXA, TAL and pentoxifylline significantly reduced cholera toxin-induced edema (DEXA(0.5 mg/kg): 42.6% of inhibition; TAL(45 mg/kg): 36% of inhibition; pentoxifylline (45 mg/kg): 61% of inhibition). Neither cholera toxin nor its B subunit induced neutrophil migration into peritoneal cavities. Cholera toxin stimulated the release of TNF-alpha by macrophages (cholera toxin(10 microg): 11.46 +/- 0.44 UI/ml). These data provide evidences that cholera toxin exhibits significant pro-inflammatory activity. It also indicates the role of TNF-alpha upon the pathophysiology of this event based on the inhibitory action of DEXA, TAL and pentoxifylline, and on TNF-alpha secretion induced by cholera toxin.

Serial analysis of cytokine mRNA profiles in whole blood samples from patients with early multiple sclerosis

In this pilot study, we serially determined the cytokine messenger RNA (mRNA) expression pattern in whole blood samples from 12 patients with clinical isolated syndrome suggestive of early multiple sclerosis (MS) using a new sensitive quantitative polymerase chain reaction (PCR) method. Significantly higher levels of tumor necrosis factor-alpha (TNF-alpha; x 5.1), interferon-gamma (IFN-gamma; x 4.8) and interleukin-10 (IL-10; x 5.6) mRNA were detected in MS patients at the time of a relapse compared to healthy controls. Treatment with i.v. methylprednisolone (MP) led to an increase of IL-4 mRNA and a significant decrease of IFN-gamma and TNF-alpha mRNA expression. In this cohort of clinically stable patients, proinflammatory cytokines remained low during the 1-year follow-up period. As several indications point to a cytokine dysregulation in MS, quantitative analysis of cytokine mRNA profiles in whole blood samples by real time PCR may be a useful immunological marker to monitor disease activity in future therapeutic trials in MS.

Effects of chlorpromazine, pentoxifylline and dexamethasone on mRNA expression of lipopolysaccharide-induced inflammatory cytokines in bovine peripheral blood mononuclear cells

The effects of chlorpromazine (CPZ), pentoxifylline (PTX) and dexamethasone (DEX) on mRNA expression of lipopolysaccharide (LPS)-induced proinflammatory cytokines were examined in bovine peripheral blood mononuclear cells (PBMCs) in vitro. The expression of inflammatory cytokine mRNAs was analyzed by RT-PCR and Southern blot hybridization in bovine PBMCs. CPZ and DEX decreased the expression of cytokine mRNA (such as interleukin-1 beta and tumor necrosis factor-alpha) after stimulation with LPS in a dose-dependent manner. However, pretreatment with PTX had no inhibitory effect on the mRNA expression of proinflammatory cytokines. These results indicated that pretreatment with CPZ and DEX might be effective to reduce the production of LPS-induced inflammatory cytokines in bovine PBMCs in vitro.

Increased levels of IL-15 mRNA in relapsing--remitting multiple sclerosis attacks

IL-15 is a proinflammatory cytokine which has recently been implicated in multiple sclerosis (MS) pathogenesis, where it may play a role in the initiation and/or progression of the disease. We have used reverse transcriptase-polymerase chain reaction (RT-PCR) to study IL-15 mRNA levels in peripheral blood mononuclear cells (PBMC) from healthy controls and relapsing-remitting MS (RRMS) patients in a stable phase of the disease and during a bout, both before and after corticosteroid treatment (CST). IL-15 mRNA expression was found to be similar in controls and stable patients. We have detected an increased level of IL-15 mRNA in PBMC of patients with a relapse, which was maintained after CST. We have also found an inverse correlation between PBMC IL-15 mRNA levels at the onset of the relapse and the time elapsed since the previous attack, as well as an absence of correlation between IL-15 mRNA levels and the patient demographic and clinical characteristics. Results in the present work further suggest a role for IL-15 in MS pathophysiology.

Pirfenidone blocks the in vitro and in vivo effects of staphylococcal enterotoxin B

Pirfenidone [5-methyl-1-phenyl-2-(1H)-pyridone] down-regulates expression of cytokines and other mediators involved in the onset and development of pulmonary fibrosis. Pirfenidone also inhibits production of tumor necrosis factor alpha (TNF-alpha) from macrophages incubated with endotoxin and protects mice against endotoxin shock. Pirfenidone's ability to reduce cytokine expression in these disorders led us to investigate the drug's effect on another cytokine anomaly, superantigen-induced shock. BALB/c mice were exposed to staphylococcal enterotoxin B (SEB) either systemically or by aerosol and subsequently potentiated with a sublethal dose of lipopolysaccharide. In these experiments, pirfenidone given 2 to 4.25 h after SEB resulted in 80 to 100% survival versus only 0 to 10% survival among untreated control animals. Relative to serum cytokine levels from controls given toxin but no drug, there was a 35 to 80% decrease in TNF-alpha, interleukin 1, and other proinflammatory cytokines. In vitro experiments with human peripheral blood lymphocytes revealed that pirfenidone reduced SEB-induced cytokine levels 50 to 80% and inhibited 95% of SEB-induced T-cell proliferation. Overall, these studies demonstrated the potential utility of pirfenidone as a therapeutic against septic shock and the biological effects of SEB.

Induction of the cyclic nucleotide phosphodiesterase PDE4B is essential for LPS-activated TNF-alpha responses

Lipopolysaccharide (LPS) stimulation of the innate immune response requires the activation of signaling cascades that culminate in the synthesis and secretion of proinflammatory cytokines. Given the inhibitory effects of phosphodiesterase (PDE) inhibitors on LPS-induced cytokine production, we have investigated LPS responses in mice deficient in PDE4 (type 4 cAMP-specific PDE)-B and PDE4D. LPS stimulation of mouse peripheral leukocytes induced PDE4B mRNA accumulation and increased PDE4 activity. This response was completely absent in mice deficient in PDE4B but not PDE4D. LPS induction of tumor necrosis factor-alpha secretion by circulating leukocytes was decreased by approximately 90% in mice deficient in PDE4B but not in mice lacking PDE4D. The impaired LPS response was evident regardless of the LPS dose used for stimulation and was associated with a more than 90% decrease in tumor necrosis factor-alpha mRNA accumulation. A decreased responsiveness to LPS was also present in other inflammatory cells, including peritoneal and lung macrophages. These findings demonstrate that PDE4B gene activation by LPS constitutes a feedback regulation essential for an efficient immune response.

Small therapeutic molecules for the treatment of inflammatory bowel disease

New therapies for inflammatory bowel disease are needed, because standard therapies fail to induce remission in about 30% of patients, and because of the relative inefficacy of current maintenance therapies. This review summarises the current status of the development of small therapeutic molecules for inflammatory bowel disease.

The proximal promoter region is essential for lipopolysaccharide induction and cyclic AMP inhibition of mouse tumor necrosis factor-alpha

Bacterial lipopolysaccharide (LPS) induces a rapid and transient increase in transcription of the tumor necrosis factor-alpha (TNF-alpha) gene in cells of monocyte/macrophage lineage. This study examines the role of potential regulatory elements within the proximal promoter region of the mouse TNF-alpha gene in LPS induction and cyclic AMP (cAMP)-mediated inhibition of TNF-alpha in RAW 264.7 murine macrophage-like cells. Transfection of proximal promoter chloramphenicol acetyltransferase (CAT) reporter constructs demonstrated that this region is LPS inducible in murine RAW 264.7 cells, with a 5.9-fold increase over nonstimulated transfectants. Site-specific mutations of the ETS, activated protein-1 (AP-1)/cAMP-responsive element (CRE)-like, or NF-kappaB-like motifs within this region caused a reduction in the LPS response by 52%, 46%, and 51%, respectively. LPS induction of the proximal promoter-CAT reporter construct was reduced by >40% by the addition of 8-bromo-cAMP (8-Br-cAMP). To determine the role of the proximal promoter region in the context of the entire TNF-alpha gene, we produced a hemagglutinin (HA)-tagged genomic TNF-alpha construct that contains a deletion of the proximal promoter region. Transfection of this construct into RAW 264.7 cells demonstrated a decrease in LPS-induced transcripts as well as a lack of response to cAMP. This suggested an essential role for this regulatory region in LPS-induced activation and cAMP inhibition of mouse TNF-alpha gene transcription in murine macrophages.

Comparison of inhibition of ovalbumin-induced bronchoconstriction in guinea pigs and in vitro inhibition of tumor necrosis factor-alpha formation with phosphodiesterase 4 (PDE4) selective inhibitors

Phosphodiesterase 4 (PDE4) inhibitors elevate cyclic adenosine 5'-monophosphate (cAMP), and this elevation has been shown to inhibit inflammatory cytokines such as tumor necrosis factor-alpha (TNF-alpha). Using TNF-alpha as a biomarker, we have developed transcription-based assays to examine inhibition of PDE4 activity in human and guinea pig whole blood. In vitro inhibition by PDE4 inhibitors was measured using quantitative PCR (qPCR) analysis of TNF-alpha mRNA levels in whole blood stimulated with lipopolysaccharide (LPS). The kinetics of human TNF-alpha mRNA production were analyzed and shown to be highest 4 hr following LPS stimulation. The guinea pig displayed kinetics of TNF-alpha transcription similar to those of the human. Analysis of inhibition of human TNF-alpha protein production was performed by immunoassay and shown to correlate with inhibition of transcription for three of the four compounds tested. Roflumilast was found to be 9-fold more potent for TNF-alpha inhibition in the qPCR assay than in the protein assay. The potencies of L-826,141 and roflumilast were determined in human and guinea pig whole blood by qPCR, with IC(50) values of 270 and 20 nM, respectively, in humans and 100 and 10 nM, respectively, in guinea pigs. These results show that the potency of PDE4 inhibitors can be monitored in whole blood using a transcription-based assay, and that this type of assay can be adapted to various species provided the TNF-alpha nucleotide sequence is known. The in vitro whole blood IC(50) for TNF-alpha inhibition was compared to inhibition in the ovalbumin-challenged guinea pig model of bronchoconstriction. Obtaining plasma levels at the IC(50) determined in vitro for L-826,141 and roflumilast provides significant inhibition of bronchoconstriction. This suggests that TNF-alpha can be used as a whole blood biomarker in the guinea pig for PDE4 inhibition in this inflammatory model.

Regulation of adrenomedullin expression and release

Adrenomedullin (AM) was originally identified in the extracts of human pheochromocytoma tissue, but this peptide is now known to be synthesized and secreted from many kinds of cells in the body, including vascular smooth muscle cells, endothelial cells, fibroblasts, cardiac myocytes, epithelial cells, and cancer cells. In this review, we summarize AM-secreting and AM gene-expressing cells in addition to the regulation of secretion and gene expression of AM. Although the data are still limited to deduce the general features of AM gene expression, synthesis, and secretion, AM is assumed to be classified into the new class of biologically active peptides, which is mainly expressed and secreted from non-endocrine type cells by the stimulation with inflammation-related substances. It is also interesting that serious physiological conditions such as inflammation or hypoxia potently stimulate AM expression and release, suggesting its unique physiological function distinct from other known biologically active peptides.

The degenerative effect of a single intranigral injection of LPS on the dopaminergic system is prevented by dexamethasone, and not mimicked by rh-TNF-alpha, IL-1beta and IFN-gamma

It is becoming widely accepted that the inflammatory response is involved in neurodegenerative disease. In this context, we have developed an animal model of dopaminergic system degeneration by the intranigral injection of lipopolysaccharide (LPS), a potent inductor of inflammation. To address the importance of the inflammatory response in the LPS-induced degeneration of nigral dopaminergic neurones, we carried out two different kinds of studies: (i) the possible protective effect of an anti-inflammatory compound, and (ii) the effect of the intranigral injection of inflammatory cytokines (TNF-alpha, IL-1beta and IFN-gamma) on dopaminergic neurones viability. Present results show that dexamethasone, a potent anti-inflammatory drug that interferes with many of the features characterizing pro-inflammatory glial activation, prevented the loss of catecholamine content, Tyrosine hydroxylase (TH) activity and TH immunostaining induced by LPS-injection and also the bulk activation of microglia/macrophages. Surprisingly, injection of the pro-inflammatory cytokines failed to reproduce the LPS effect. Taken together, our results suggest that inflammatory response is implicated in LPS-induced neurodegeneration. This damage may be due, at least in part, to a cascade of events independent of that described for TNF-alpha/IL-1 beta/IFN-gamma.

Dexamethasone inhibits the inducible bioconversion of glyceryl trinitrate to nitric oxide

The aim of this study was to assess the effects of dexamethasone (DEX) on the inducible bioconversion of glyceryl trinitrate (GTN) into nitric oxide in cultured smooth muscle cells, endothelial cells, and the J774 macrophage cell line as well as in vivo and ex vivo in rats either untreated or pretreated with Escherichia coli lipopolysaccharide. In vitro, an increased bioconversion of GTN to nitrite and an elevation of cyclosine guanosine 3,5;-monophosphate (cGMP) levels occurred after treatment with lipopolysaccharide (LPS) (0.5 microg/ml, 18 h). This effect was ablated by co-incubation with DEX (10 microM, 18 h). Rats treated with an intraperitoneal (IP) injection of LPS (4 mg/kg) 18 h beforehand showed enhanced hypotensive responses to GTN (1 mg/kg, intravenously [IV]) and this was prevented when DEX (4 mg/kg, IP) was given together with LPS. Progesterone (50 mg/kg, IP) had no effect on GTN-induced hypotensive response. Conversely, exposure of rat aortic strips obtained from animals pretreated with LPS produced an enhanced vasorelaxant response in LPS-treated rats. Also, this effect was inhibited by pretreatment with DEX. Thus, the induction of the pathway leading to the formation of nitric oxide from GTN is blocked by DEX both in vitro and in vivo, and this may represent a useful tool in the assessment of the enhanced bioconversion of organic nitrates into nitric oxide occurring via inflammatory mechanisms.

Endotoxin antagonism: conceptual basis and therapeutic potential

Since antiquity, physicians have beheld infections with deep consternation, knowing that a local lesion can have horrific systemic effects. Even in modern times, these effects have generally been impossible to control. Until recently, their ultimate cause was not well understood. Now, within the space of only a few years, the proximal cause of sepsis has been identified. Paralogous members of the Toll-like receptor (TLR) family sense infection and ignite the systemic inflammatory reaction that is known as sepsis. The question at hand has become a practical one: can this understanding be exploited to a therapeutic advantage?

Effects of pentoxifylline on pulmonary function and results of cytologic examination of bronchoalveolar lavage fluid in horses with recurrent airway obstruction

OBJECTIVES

To determine the effects of pentoxifylline (PTX) administration on lung function and results of cytologic examination of bronchoalveolar lavage fluid in horses affected by recurrent airway obstruction (RAO).

ANIMALS

10 RAO-affected horses.

PROCEDURES

6 horses were orally administered PTX (16 g) mixed with corn syrup, and 4 horses were administered corn syrup alone, twice daily for 14 days. Pulmonary function was evaluated before administration (day 0) and on days 8 and 15. Bronchoalveolar lavage (BAL) was performed on days 0 and 15. Reversibility of airway obstruction was assessed by measuring pulmonary function before and after administration of atropine (0.02 mg/kg, IV). Serum concentration of PTX was measured in 4 horses 30 minutes and 2 and 4 hours after administration of PTX on days 1, 2, 3, 7 and 14.

RESULTS

Administration of PTX to BAO-affected horses resulted in a decrease in elastance value on day 8 and on elastance and resistance (RL) values on days 8 and 15. Results for cytologic examination of BAL fluid obtained on day 15 did not differ significantly, compared with values for day 0. Values of RL decreased in all horses following administration of atropine. When mixed in corn syrup and administered orally, PTX was poorly absorbed in horses, and there was noticeable variation in serum PTX concentrations over time and among horses.

CONCLUSIONS AND CLINICAL RELEVANCE

Based on these results, it can be concluded that administration of PTX at high doses improved respiratory function of RAO-affected horses maintained in an unfavorable environment.

Pentoxifylline reverses oxidative mitochondrial defect in claudicating skeletal muscle

OBJECTIVE

Previous morphologic studies and phosphorus nuclear magnetic resonance spectroscopy (31P MRS) have suggested a primary mitochondrial defect in claudicating skeletal muscle. We hypothesized that pentoxifylline may alleviate this defect.

METHODS

The response of calf muscle bioenergetics to pentoxifylline was evaluated in 10 male, nondiabetic claudicants with 31P MRS and standard treadmill testing before and after 12 weeks of pentoxifylline therapy. Phosphocreatine (PCr) and adenosinodiphosphate (ADP) recovery rate constants, two very sensitive measures of oxidative mitochondrial function, were measured.

RESULTS

Seven of the 10 subjects had abnormal baseline PCr (<0.015 s(-1)) and ADP (<0.024 s(-1)) recovery rate constants. These 7 had significant improvement in mitochondrial function with pentoxifylline; their PCr recovery rate constants increased from 0.009 +/- 0.002 to 0.013 +/- 0.002 s(-1) (P = 0.013) and their ADP recovery rate constants increased from 0.015 +/- 0.002 to 0.022 +/- 0.002 s(-1) (P = 0.004). The remaining 3 patients had normal baseline constants and demonstrated no improvement after pentoxifylline therapy. Baseline PCr and ADP recovery rate constants inversely correlated with their corresponding percentage of improvement after pentoxifylline (P < 0.05). In addition the percentage of improvement in the PCr and ADP recovery rate constants correlated with the percentage of improvement in initial claudication distance and maximum walking capacity (P < 0.05).

CONCLUSIONS

Pentoxifylline improves the mitochondriopathy of claudicating muscle, producing the most improvement in limbs with the worse baseline mitochondrial function. These results point to a potential new mode of action for pentoxifylline in the treatment of claudication and identify a subgroup of patients with the best potential for improvement with treatment.

Regulation of adrenomedullin secretion from cultured cells

Characterization of immunoreactive adrenomedullin (AM) secreted from cultured human vascular smooth muscle cells and 7 other cells indicates that AM is synthesized and secreted from all cultured cells we surveyed. The secretion rate of AM measured ranges from 0.001-6.83 fmol/10(5) cells/h, and endothelial cells, vascular smooth muscle cells and fibroblasts generally secrete AM at high rates. Based on the results of regulation of AM secretion from vascular wall cells, fibroblasts, macrophages and other cells measured in this and previous studies, AM secretion is found to be generally stimulated by inflammatory cytokines, lipopolysaccharide (LPS) and hormones. Especially, vascular smooth muscle cells and fibroblasts elicited uniform and strong stimulatory responses of AM secretion to tumor necrosis factor (TNF), interleukin-1 (IL-1), LPS and glucocorticoid, but endothelial cells did not elicit such prominent responses. AM secretion of monocyte-macrophage was mainly regulated by the degree of differentiation into macrophage and activation by LPS and inflammatory cytokines including interferon-gamma. The other examined cells showed weaker responses to LPS and IL-1. Although cultured cells may have been transformed as compared with those in the tissue, these data indicate that AM is widely synthesized and secreted from most of the cells in the body and functions as a local factor regulating inflammation and related reactions in addition to as a potent vasodilator. The responses of AM secretion to LPS and inflammatory cytokines suggest that fibroblasts, vascular smooth muscle cells and macrophage are the major sources of AM in the septic shock.

Anti-TNF therapy for rheumatoid arthritis and other inflammatory diseases

The availability of agents that block the biological activity of tumor necrosis factor alpha (TNF alpha) in rheumatoid arthritis (RA) has permitted studies that confirm the key role of this cytokine in the pathogenesis of this disease. To date, two anti-TNF agents, infliximab and etanercept, have been approved for use in treatment. Clinical trials of these agents demonstrate efficacy for the control of symptoms and signs and acceptable safety in patients who have failed to respond adequately to conventional therapy. Combination with methotrexate appears to be particularly effective and may provide the main initial indication for clinical application in the first instance. Repeated administration of anti-TNF therapies over a one year period results in sustained reduction in symptoms and signs of RA in the majority of patients. It has recently become apparent that anti-TNF therapy protects joints from structural damage. These findings imply that TNF alpha has a critical role in the bone and cartilage damage associated with RA. Evidence to date support the hypothesis that there are 2 particularly important mechanisms of action; deactivation of the proinflammatory cytokine cascade at the site of inflammation and diminished recruitment of inflammatory cells from blood to the rheumatoid joint.

The role of tumor necrosis factor in cardiac disease

Tumor necrosis factor (TNF) is a proinflammatory cytokine that can produce widespread deleterious effects when expressed in large amounts. It is produced in the heart by both cardiac myocytes and resident macrophages under conditions of cardiac stress, and is thought to be responsible for many of the untoward manifestations of cardiac disease. This article discusses the role of TNF in heart disease and some potential therapeutic modalities that can influence the cytokine activity. The results of controlled studies would suggest that TNF inhibition does not influence the clinical course of patients with heart failure.

Pentoxifylline, Ciprofloxacin and Dexamethasone Improve the Ineffective Hematopoiesis in Myelodysplastic Syndrome Patients; Malignancy

Twenty-five patients with a diagnosis of myelodysplastic syndromes (MDS) were randomized to either begin therapy with pentoxifylline, ciprofloxacin and dexamethasone (PCD) immediately (10 patients) or after a 12 week observation period (control arm, 15 patients). PCD was administered with the goal of suppressing cytokine-induced excessive intramedullary apoptosis of hematopoietic cells. No marked fluctuations of blood counts were noted during the period of observation. Twenty-two patients completed at least 12 weeks of therapy: 18/22 showed some type of hematologic response, 9/18 showing an improvement in absolute neutrophil count only (p = < 0.001) and 9/18 showing multi-lineage responses. No unique category of MDS responded better, however 19/25 patients had refractory anemia (RA)/RA with ringed sideroblasts. The median time to response was 6 weeks and 3/18 responding patients maintained their responses beyond a year. We conclude that hematologic improvement in response to PCD therapy supports the validity of this unique anti-cytokine approach. Future trials should combine PCD therapy with established approaches (growth factors/chemotherapy) and also should focus on identifying more effective ways of suppressing the pro-apoptotic cytokines in MDS.

Suppression of experimental systemic lupus erythematosus (SLE) in mice via TNF inhibition by an anti-TNFalpha monoclonal antibody and by pentoxiphylline

We have previously shown that the clinical manifestations of experimental systemic lupus erythematosus (SLE) correlate with an early increased secretion of TNFalpha and IL-1. In the present study, we examined the efficacy of two therapeutic modalities which lower TNFalpha production or activity, on the clinical manifestations of the disease. Experimental SLE was induced in naive C3H.SW mice by injection of the human anti-DNA monoclonal antibody (mAb) bearing the common idiotype, 16/6 Id. Two weeks after booster injections, treatment with either an anti-TNFalpha mAb, or pentoxiphylline (PTX) was started, for a period of 6 weeks. Production of TNFalpha (by splenocytes) and IL-1 (by peritoneal macrophages) was determined 3 and 7 months after disease induction. The experimental mice were also followed for disease manifestations. Both treatment protocols, with anti-TNFalpha mAb and with PTX, reduced the production of the two pro-inflammatory cytokines. TNFalpha and IL-1, in mice with experimental SLE. Anti-DNA antibodies were significantly lower in the mice treated with either protocol. In addition, a significantly lower rate of leukopenia, proteinuria and immune complex deposition was observed in treated mice. Abrogation of TNFalpha and IL-1 production in the early stages of experimental SLE by an anti-TNFalpha mAb or by PTX improves the clinical status of mice afflicted with this autoimmune disease.

C-type natriuretic peptide is synthesized and secreted from leukemia cell lines, peripheral blood cells, and peritoneal macrophages

OBJECTIVE

C-type natriuretic peptide (CNP) is the third member of the natriuretic peptide family. Cultured endothelial cells secrete CNP, and its secretion rate from the endothelial cells is augmented by lipopolysaccharide, interleukin-1beta, and tumor necrosis factor-alpha, which participate in the pathophysiology of inflammation. In this study, we investigated the regulation of CNP secretion from monocytes and macrophages to estimate its contribution to the progression of inflammation.

MATERIALS AND METHODS

CNP secretion rates from two human leukemia cell lines (THP-1 and HL-60), human peripheral blood lymphocytes, granulocytes, monocytes, monocyte-derived macrophages, and mouse peritoneal macrophages were measured under conditions with or without stimulation. Immunoreactive CNP levels in the culture media of these cells were measured by a specific radioimmunoassay.

RESULTS

The secretion rates of CNP from THP-1 and HL-60 cells were augmented according to the degree of their differentiation into macrophage-like cells under the stimulation with phorbol ester. Peripheral blood monocytes also increased the CNP secretion rate after their differentiation into macrophages. Retinoic acid elicited synergistic effects on the CNP secretion rate from HL-60 cells when administered with lipopolysaccharide, interferon-gamma, interleukin-1beta, tumor necrosis factor-alpha, or phorbol ester. In contrast, the phorbol ester-stimulated CNP secretion rate from THP-1 cells was suppressed with dexamethasone, which inhibits monocyte differentiation into macrophage.

CONCLUSIONS

The secretion rate of CNP from monocytes was shown to be regulated based on the degree of their differentiation. This study provides evidence that the monocyte/macrophage system is one of the sources of CNP, especially under inflammatory conditions.

Immunohistochemical analysis of cellular infiltrate and gamma interferon, interleukin-12, and inducible nitric oxide synthase expression in leprosy type 1 (reversal) reactions before and during prednisolone treatment

The effects of prednisolone treatment on the cellularity and cytokine (gamma interferon, interleukin-12, and inducible nitric oxide synthase) profiles of leprosy skin type 1 (reversal) reactions were studied using immunohistochemistry. Skin biopsies were taken from 15 patients with leprosy type 1 (reversal) reactions at days 0, 7, 28, and 180 after the start of steroid treatment. Prednisolone treatment had little effect at day 7, but by day 28 significant decreases were found in cytokine levels. Some patients maintained cytokine production at days 28 and 180. These results illustrate the strong Th1 profile of type 1 reactional lesions, the slow response to steroid therapy, and continuing activity at 180 days.

Cytokines and etiopathogenesis of pervasive developmental disorders

Autistic disorder, also known as early infantile autism, is a developmental disorder of unknown etiology. However, there is some evidence to suggest that abnormalities of the immune system mediate the pathophysiology of autistic disorder. Cytokines, which play a pivotal role in initiating and maintaining immune responses, have been implicated in the etiopathogenesis of major neuropsychiatric disorders including autism. Cytokines are synthesized in the periphery, as well as in the central nervous system, and exert their effects by binding to their receptors in the nervous tissues. It is suggested that, in genetically predisposed individuals, overproduction or decreased synthesis of certain cytokines may result in neurodevelopmental arrest and/or neurotoxicity.

Managing cancer-related anorexia/cachexia

Cancer-related anorexia/cachexia (CAC) is a complex phenomenon in which metabolic abnormalities, proinflammatory cytokines produced by the host immune system, circulating tumour-derived catabolic factors, decreased food intake, and probably additional unknown factors, all play different roles. This review examines the mechanisms of CAC and its management. All the potential modalities of intervention from nutritional to pharmacological approaches are included with a clear distinction between unproven, investigational and well established treatments. Among the latter, the progestogens are currently considered the most effective and safest drugs for the management of CAC. Agents currently under investigation for CAC include thalidomide, pentoxifylline and melatonin, which most probably act on cytokine release, and clenbuterol, which acts on muscle mass and to antagonise protein wasting. Our personal experience with the synthetic progestogens megestrol and medroxyprogesterone supports their use as first-line agents. In addition, our work on the potential role of antioxidant agents in counteracting the oxidative stress, which appears to be involved in CAC, shows them to be promising agents when used in combination chemotherapy regimens either alone or with other 'biologics'. There is an ongoing need for quality of life questionnaires which specifically address the most significant symptoms present in patients with CAC.

Cancer cachexia: a therapeutic approach

Cancer cachexia is a complex syndrome which occurs in more than two-thirds of patients who die with advanced cancer. The main components of this pathological state are anorexia and metabolic abnormalities such as glucose intolerance, fat depletion, and muscle protein catabolism among others. The aim of the present study is to review the different therapeutic approaches that have been designed to fight and counteract cancer cachexia.

Pentoxifylline improves short-term survival in severe acute alcoholic hepatitis: a double-blind, placebo-controlled trial

BACKGROUND & AIMS

An earlier pilot study from our liver unit suggested benefit from treatment with pentoxifylline (PTX), an inhibitor of tumor necrosis factor (TNF), in severe acute alcoholic hepatitis. The aim of the present study was to evaluate this treatment in a larger cohort of patients.

METHODS

One hundred one patients with severe alcoholic hepatitis (Maddrey discriminant factor > or = 32) entered a 4-week double-blind randomized trial of PTX (400 mg orally 3 times daily) vs. placebo. Primary endpoints of the study were the effect of PTX on (1) short-term survival and (2) progression to hepatorenal syndrome. On randomization, there were no differences in demographic and clinical characteristics or laboratory values (including TNF) between the 2 groups.

RESULTS

Twelve (24.5%) of the 49 patients who received PTX and 24 (46.1%) of the 52 patients who received placebo died during the index hospitalization (P = 0.037; relative risk, 0.59; 95% confidence interval, 0.35-0.97). Hepatorenal syndrome was the cause of death in 6 (50%) and 22 (91.7%) patients (P = 0.009; relative risk, 0.29; 95% confidence interval, 0.13-0.65). Three variables (age, creatinine level on randomization, and treatment with PTX) were independently associated with survival. TNF values on randomization were not predictive of survival; however, during the study period they increased markedly in nonsurvivors compared with survivors in both groups.

CONCLUSIONS

Treatment with PTX improves short-term survival in patients with severe alcoholic hepatitis. The benefit appears to be related to a significant decrease in the risk of developing hepatorenal syndrome. Increasing TNF levels during the hospital course are associated with an increase in mortality rate.

Inhibition of TNF-alpha production contributes to the attenuation of LPS-induced hypophagia by pentoxifylline

Cytokines such as tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) are assumed to mediate anorexia during bacterial infections. To improve our understanding of the role that these two cytokines serve in mediating infection during anorexia, we investigated the ability of pentoxifylline (PTX), a potent inhibitor of TNF-alpha production, to block the anorectic effects of the bacterial products lipopolysaccharide (LPS) and muramyl dipeptide (MDP) in rats. Intraperitoneally injected PTX (100 mg/kg body wt) completely eliminated the anorectic effect of intraperitoneally injected LPS (100 microg/kg body wt) and attenuated the anorectic effect of a higher dose of intraperitoneally injected LPS (250 microg/kg body wt). Concurrently, PTX pretreatment suppressed low-dose LPS-induced TNF-alpha production by more than 95% and IL-1beta production 39%, as measured by ELISA. Similarly, high-dose LPS-induced TNF-alpha production was reduced by approximately 90%. PTX administration also attenuated the tolerance that is normally observed with a second injection of LPS. In addition, PTX pretreatment attenuated the hypophagic effect of intraperitoneally injected MDP (2 mg/kg body wt) but had no effect on the anorectic response to intraperitoneally injected recombinant human TNF-alpha (150 ug/kg body wt). The results suggest that suppression of TNF-alpha production is sufficient to attenuate LPS- and MDP-induced anorexia. This is consistent with the hypothesis that TNF-alpha plays a major role in the anorexia associated with bacterial infection.

Anti-inflammatory effects of ergotamine in steers

The objective of this experiment was to investigate whether the ergot alkaloid, ergotamine (ET), an alkaloid used to model fescue toxicosis in cattle, modifies the response of cattle to endotoxin (LPS) challenge. Steers (n = 16) were divided into the following treatment groups: control (C), ergotamine (ET), endotoxin (LPS), and ET + LPS. ET and ET + LPS groups received a single bolus intravenous injection of ET (40 microg. kg. body wt(-1)), whereas C and LPS steers received a single bolus injection of sterile vehicle. Thirty minutes after ET/vehicle administration, a single bolus intravenous injection of LPS (0.2 microg. kg. body wt(-1)) was given. Blood was collected at various time points for 48 hr post. Endotoxin increased rectal temperature (RT) and the circulating levels of tumor necrosis factor-alpha (TNF-alpha), cortisol, haptoglobin (Hp), thromboxane B(2) (TXB(2)). The circulating Hp, TNF-alpha, and TXB(2) increases were blunted by pretreatment with ET compared with ET + LPS. Ergotamine by itself increased circulating cortisol and RT, whereas it decreased serum prolactin (PRL). Therefore, whereas administration of LPS at 0.2 microg/kg to steers resulted in an expected response, the combination of ET + LPS attenuated major effects of LPS alone. Thus, acute administration of ET appeared to be anti-inflammatory as it decreased the inflammatory response to LPS, an effect likely driven at least in part by the ET-caused cortisol increase.

Tumour necrosis factor levels during acute rejection and acute tubular necrosis in renal transplant recipients

Plasma tumour necrosis factor levels were measured serially in 16 patients following renal transplantation, and in 10 patients on haemodialysis and in 12 patients on peritoneal dialysis. The patients on peritoneal dialysis had lower plasma TNF levels than the patients on haemodialysis. There was a decrease in TNF levels immediately following renal transplantation; this is probably related to the bolus doses of methylprednisolone administered intra-operatively. Patients with acute rejection had higher levels of TNF than non-rejecting patients. The increase in TNF levels in rejecting patients was observed 2 days before the clinical manifestation of acute rejection. There was a marked decrease in TNF levels in rejecting patients in response to treatment with steroids. Patients with delayed graft function had higher levels of TNF on the first post-operative day compared to patients with immediate function. These changes in plasma TNF levels following renal transplantation have important clinical and therapeutic implications.