The differential effect of pentoxifylline on cytokine production by alveolar macrophages and its clinical implications

Pentoxifylline-induced protein expression change in RAW 264.7 cells as determined by immunoprecipitation-based high performance liquid chromatography

Although pentoxifylline (PTX) was identified as a competitive non-selective phosphodiesterase inhibitor, its pharmacological effect has not been clearly elucidated. The present study explored the effect of low dose 10 μg/mL PTX (therapeutic dose) compared to high dose 300 μg/mL PTX (experimental dose) in RAW 264.7 cells through immunoprecipitation-based high performance liquid chromatography (IP-HPLC), immunohistochemistry, and western blot. 10 μg/mL PTX increased the expression of proliferation (Ki-67, PCNA, cyclin D2, cdc25A), epigenetic modification (KDM4D, PCAF, HMGB1), protein translation (DOHH, DHPS, eIF5A1), RAS signaling (KRAS, pAKT1/2/3, PI3K), NFkB signaling (NFkB, GADD45, p38), protection (HSP70, SOD1, GSTO1/2), survival (pAKT1/2/3, SP1, sirtuin 6), neuromuscular differentiation (NSEγ, myosin-1a, desmin), osteoblastic differentiation (BMP2, RUNX2, osterix), acute inflammation (TNFα, IL-1, CXCR4), innate immunity (β-defensin 1, lactoferrin, TLR-3, -4), cell-mediated immunity (CD4, CD8, CD80), while decreased the expression of ER stress (eIF2α, eIF2AK3, ATF6α), fibrosis (FGF2, CTGF, collagen 3A1), and chronic inflammation (CD68, MMP-2, -3, COX2) versus the untreated controls. The activation of proliferation by 10 μg/mL PTX was also supported by the increase of cMyc-MAX heterodimer and β-catenin-TCF1 complex in double IP-HPLC. 10 μg/mL PTX enhanced FAS-mediated apoptosis but diminished p53-mediated apoptosis, and downregulated many angiogenesis proteins (angiogenin, VEGF-A, and FLT4), but upregulated HIF1α, VEGFR2, and CMG2 reactively. Whereas, 300 μg/mL PTX consistently decreased proliferation, epigenetic modification, RAS and NFkB signaling, neuromuscular and osteoblastic differentiation, but increased apoptosis, ER stress, and fibrosis compared to 10 μg/mL PTX. These data suggest PTX has different biological effect on RWA 264.7 cells depending on the concentration of 10 μg/mL and 300 μg/mL PTX. The low dose 10 μg/mL PTX enhanced RAS/NFkB signaling, proliferation, differentiation, and inflammation, particularly, it stimulated neuromuscular and osteoblastic differentiation, innate immunity, and cell-mediated immunity, but attenuated ER stress, fibrosis, angiogenesis, and chronic inflammation, while the high dose 300 μg/mL PTX was found to alleviate the 10 μg/mL PTX-induced biological effects, resulted in the suppression of RAS/NFkB signaling, proliferation, neuromuscular and osteoblastic differentiation, and inflammation.

Can pentoxifylline and similar xanthine derivatives find a niche in COVID-19 therapeutic strategies? A ray of hope in the midst of the pandemic

COVID-19 pandemic presents an unprecedented challenge to identify effective drugs for treatment. Despite multiple clinical trials using different agents, there is still a lack of specific treatment for COVID-19. Having the potential role in suppressing inflammation, immune modulation, antiviral and improving respiratory symptoms, this review discusses the potential role of methylxanthine drugs like pentoxifylline and caffeine in the management of COVID-19 patients. COVID-19 pathogenesis for clinical features like severe pneumonia, acute lung injury (ALI) / acute respiratory distress syndrome (ARDS), and multi-organ failures are excessive inflammation, oxidation, and cytokine storm by the exaggerated immune response. Drugs like pentoxifylline have already shown improvement of the symptoms of ARDS and caffeine has been in clinical use for decades to treat apnea of prematurity (AOP) in preterm infants and improve respiratory function. Pentoxifylline is well-known anti-inflammatory and anti-oxidative molecules that have already shown to suppress Tumor Necrosis Factor (TNF-α) as well as other inflammatory cytokines in pulmonary diseases, and this may be beneficial for better clinical outcomes in COVID-19 patients. Pentoxifylline enhances blood flow, improves microcirculation and tissue oxygenation, and caffeine also efficiently improves tissue oxygenation, asthma, decreases pulmonary hypertension and an effective analgesic. There are significant shreds of evidence that proved the properties of pentoxifylline and caffeine against virus-related diseases as well. Along with the aforementioned evidences and high safety profiles, both pentoxifylline and caffeine offer a glimpse of considerations for future use as a potential adjuvant to COVID-19 treatment. However, additional clinical studies are required to confirm this speculation.

Differential Effects of Pentoxifylline on Learning and Memory Impairment Induced by Hypoxic-ischemic Brain Injury in Rats

Objective

Hypoxic-ischemic (HI) brain injury in the human perinatal period often leads to significant long-term neurobehavioral dysfunction in the cognitive and sensory-motor domains. Using a neonatal HI injury model (unilateral carotid ligation followed by hypoxia) in postnatal day seven rats, the present study investigated the long-term effects of HI and potential behavioral protective effect of pentoxifylline.

Methods

Seven-day-old rats underwent right carotid ligation, followed by hypoxia (F_iO₂ = 0.08). Rats received pentoxifylline immediately after and again 2 hours after hypoxia (two doses, 60‒100 mg/kg/dose), or serum physiologic. Another set of seven-day-old rats was included to sham group exposed to surgical stress but not ligated. These rats were tested for spatial learning and memory on the simple place task in the Morris water maze from postnatal days 77 to 85.

Results

HI rats displayed significant tissue loss in the right hippocampus, as well as severe spatial memory deficits. Low-dose treatment with pentoxifylline resulted in significant protection against both HI-induced hippocampus tissue losses and spatial memory impairments. Beneficial effects are, however, negated if pentoxifylline is administered at high dose.

Conclusion

These findings indicate that unilateral HI brain injury in a neonatal rodent model is associated with cognitive deficits, and that low dose pentoxifylline treatment is protective against spatial memory impairment.

Identification of Drug Candidates to Suppress Cigarette Smoke-induced Inflammation via Connectivity Map Analyses

Cigarette smoking is the main risk factor for chronic obstructive pulmonary disease, and to date, existing pharmacologic interventions have been ineffective at controlling inflammatory processes associated with the disease. To address this issue, we used the Connectivity Map (cMap) database to identify drug candidates with the potential to attenuate cigarette smoke-induced inflammation. We queried cMap using three independent in-house cohorts of healthy nonsmokers and smokers. Potential drug candidates were validated against four publicly available human datasets, as well as six independent datasets from cigarette smoke-exposed mice. Overall, these analyses yielded two potential drug candidates: kaempferol and bethanechol. Subsequently, the efficacy of each drug was validated in vivo in a model of cigarette smoke-induced inflammation. BALB/c mice were exposed to room air or cigarette smoke and treated with each of the two candidate drugs either prophylactically or therapeutically. We found that kaempferol, but not bethanechol, was able to reduce cigarette smoke-induced neutrophilia, both when administered prophylactically and when administered therapeutically. Mechanistically, kaempferol decreased expression of IL-1α and CXCL5 concentrations in the lung. Our data suggest that cMap analyses may serve as a useful tool to identify novel drug candidates against cigarette smoke-induced inflammation.

Silica-induced fibrosis: an ancient response from the early metazoans

Exposure to crystalline silica particles causes silicosis, an occupational disease leading to an overproduction of collagen in the lung. The first step of this pathology is characterized by the release of inflammatory mediators. Tumour necrosis factor (TNF) is a pro-inflammatory cytokine directly involved in silica-induced pulmonary fibrosis. The marine demosponge Chondrosia reniformis is able to incorporate silica grains and partially dissolve the crystalline forms apparently without toxic effects. In the present work, C. reniformis tissue explants were treated with fine quartz dust and the expression level of fibrogenic genes was assayed by qPCR, demonstrating an overexpression of a fibrillar and a non-fibrillar collagen and of prolyl-4-hydroxylase enzyme. The deposition of new collagen could also be documented in quartz-treated sponge explants. Furthermore, TNF pro-inflammatory cytokine overexpression and involvement in silica-induced sponge collagen biosynthesis was demonstrated in quartz-treated explants as compared with controls by means of specific TNF inhibitors affecting the fibrogenic gene response. As no documentable detrimental effect was observed in treated explants, we conclude that the C. reniformis unique quartz engulfment and erosion is physiological and beneficial to the animal, leading to new collagen synthesis and strengthening of the body stiffness. Thus, we put forward the hypothesis that an ancient physiological behaviour from the lowest of the Metazoa, persisting through evolution via the same molecular mediators such as TNF, may have become the cause of disease in the specialized tissues of higher animals such as mammals.

Aeromonas hydrophila-induced alterations in cytosolic calcium activate pro-apoptotic cPKC-MEK1/2-TNFα axis in infected headkidney macrophages of Clarias gariepinus

Alterations in intracellular-calcium (Ca²⁺)_i homeostasis is critical to Aeromonas hydrophila-induced headkidney macrophages (HKM) apoptosis of Clarias gariepinus, though the implications are poorly understood. Here, we describe the role of intermediate molecules of Ca^2+-signaling pathway that are involved in HKM apoptosis. We observed phosphoinositide-3-kinase/phospholipase C is critical for (Ca²⁺)_i release in infected HKM. Heightened protein kinase-C (PKC) activity and phosphorylation of MEK1/2-ERK1/2 was noted which declined in presence of 2-APB, Go6976 and PD98059, inhibitors to IP3-receptor, conventional PKC isoforms (cPKC) and MEK1/2 respectively implicating Ca²⁺/cPKC/MEK-ERK1/2 axis imperative in A. hydrophila-induced HKM apoptosis. Significant tumor necrosis factor-α (TNFα) production and its subsequent reduction in presence of MEK-ERK1/2 inhibitor U0126 suggested TNFα production downstream to cPKC-mediated signaling via MEK1/2-ERK1/2 pathway. RNAi and inhibitor studies established the role of TNFα in inducing caspase-8-mediated apoptosis of infected HKM. We conclude, alterations in A. hydrophila-induced (Ca²⁺)i alterations activate cPKC-MEK1/2-ERK1/2-TNFα signaling cascade triggering HKM apoptosis.

Effects of pentoxifylline on inflammatory markers and blood pressure: a systematic review and meta-analysis of randomized controlled trials

INTRODUCTION

Pentoxifylline is a xanthine derivative with potential cardiovascular benefits.

AIM

To evaluate the impact of pentoxifylline on blood pressure (BP) and plasma TNF-α, C-reactive protein (CRP) and IL-6 through a systematic review and meta-analysis of randomized controlled trials.

METHODS

The protocol was registered (PROSPERO: CRD42016035988). The search included PUBMED, ProQuest, Scopus and EMBASE until 1 September 2015 to identify trials reporting BP or inflammatory markers during pentoxifylline therapy. Quantitative data synthesis was performed using a random-effects model, with weighted mean difference (WDF) and 95% confidence intervals (CIs) as summary statistics.

RESULTS

Fifteen studies (16 treatment arms) were found to be eligible for inclusion. Meta-analysis did not suggest any effect of pentoxifylline on either SBP or DBP. Pentoxifylline treatment was associated with a significant reduction in plasma concentrations of TNF-α (WDF: -1.03 pg/ml, 95% CI: -1.54, -0.51; P < 0.001, 11 treatment arms) and CRP (WDF: -1.39 mg/l, 95% CI: -2.68, -0.10; P = 0.034, five treatment arms). No alteration in plasma IL-6 concentration was observed. The impact of pentoxifylline on plasma TNF-α levels was found to be positively associated with treatment duration (slope: 0.031; 95% CI: 0.004, 0.057; P = 0.023) but independent of pentoxifylline dose (slope: -0.0003; 95% CI: -0.002, 0.001; P = 0.687).

CONCLUSION

Pentoxifylline did not alter BP or plasma IL-6 concentration, but significantly reduced circulating TNF-α and CRP concentrations.

Molecular characterization and expression analysis of the first Porifera tumor necrosis factor superfamily member and of its putative receptor in the marine sponge Chondrosia reniformis

Here we report the molecular cloning and characterization of the first Tumor Necrosis Factor homologous and of its putative receptor in the marine sponge Chondrosia reniformis: chTNF and chTNFR, respectively. The deduced chTNF amino acid sequence is a type II transmembrane protein containing the typical TNFSF domain. Phylogenetic analysis reveals that chTNF is more related to Chordata TNFs rather than to other invertebrates. chTNF and chTNFR are constitutively expressed both in the ectosome and in the choanosome of the sponge, with higher levels in the ectosome. chTNF and chTNFR mRNAs were monitored in sponge fragmorphs treated with Gram(+) or Gram(-) bacteria. chTNF was significantly upregulated in Gram(+)-treated fragmorphs as compared to controls, while chTNFR was upregulated by both treatments. Finally, the possible chTNF fibrogenic role in sponge fragmorphs was studied by TNF inhibitor treatment measuring fibrillar and non fibrillar collagen gene expression; results indicate that the cytokine is involved in sponge collagen deposition and homeostasis.

Hepatopulmonary Syndrome and Liver Transplantation: A Recent Review of the Literature

A severe and common pulmonary vascular complication of liver disease is hepatopulmonary syndrome (HPS). It is a triad of liver dysfunction and/or portal hypertension, intrapulmonary vascular dilatations, and increased alveolar-arterial oxygen gradient. Prevalence varies according to various study groups from 4%-47%. While the most common presenting symptom of HPS is dyspnea, it is usually asymptomatic, and thus all liver transplant candidates should be screened for its presence. Pulse oximetry is a useful screening method, but arterial blood gas examination is the gold standard. If there is an abnormal P (A-a)O2 gradient, microbubble transthoracic echocardiography should be done for diagnosis. Outcome is unpredictable, and there is currently no effective medical therapy. The only effective therapy is considered to be liver transplantation. Complete resolution of HPS after liver transplantation is seen within a year in most HPS patients.

Molecular Cloning, Characterization, and Expression Analysis of a Prolyl 4-Hydroxylase from the Marine Sponge Chondrosia reniformis

Prolyl 4-hydroxylase (P4H) catalyzes the hydroxylation of proline residues in collagen. P4H has two functional subunits, α and β. Here, we report the cDNA cloning, characterization, and expression analysis of the α and β subunits of the P4H derived from the marine sponge Chondrosia reniformis. The amino acid sequence of the α subunit is 533 residues long with an M r of 59.14 kDa, while the β subunit counts 526 residues with an M r of 58.75 kDa. Phylogenetic analyses showed that αP4H and βP4H are more related to the mammalian sequences than to known invertebrate P4Hs. Western blot analysis of sponge lysate protein cross-linking revealed a band of 240 kDa corresponding to an α2β2 tetramer structure. This result suggests that P4H from marine sponges shares the same quaternary structure with vertebrate homologous enzymes. Gene expression analyses showed that αP4H transcript is higher in the choanosome than in the ectosome, while the study of factors affecting its expression in sponge fragmorphs revealed that soluble silicates had no effect on the αP4H levels, whereas ascorbic acid strongly upregulated the αP4H mRNA. Finally, treatment with two different tumor necrosis factor (TNF)-alpha inhibitors determined a significant downregulation of αP4H gene expression in fragmorphs demonstrating, for the first time in Porifera, a positive involvement of TNF in sponge matrix biosynthesis. The molecular characterization of P4H genes involved in collagen hydroxylation, including the mechanisms that regulate their expression, is a key step for future recombinant sponge collagen production and may be pivotal to understand pathological mechanisms related to extracellular matrix deposition in higher organisms.

Pharmacological treatment for hepatopulmonary syndrome

AIM

Hepatopulmonary syndrome is a pulmonary dysfunction in the context of liver cirrhosis characterized by arterial deoxygenation. Affected patients have increased morbidity and mortality, and many of them expire before undergoing liver transplantation. Therefore, finding medical therapy as a bridge to transplantation or as a final treatment is necessary. In this study, we aimed to review the current literature about pharmacological options available for treatment of hepatopulmonary syndrome.

METHODS

A PubMED and Scopus search was conducted in January 2013 on the English literature published in any time period to find human and animal studies reporting pharmacological therapy of hepatopulmonary syndrome.

RESULTS

Out of 451 studies, 29 relevant articles were included. The number of patients, type, dose, duration, and mechanism of drugs in these studies was extracted and summarized separately. Most of pharmacologic agents act through inhibition of nitric oxide synthase and reduction in nitric oxide production, inactivation of endothelin-1, and treatment of bacterial translocation and pulmonary angiogenesis.

CONCLUSION

Several drugs have been applied for the treatment of HPS with conflicting results. However, no large randomized trial has been conducted probably due to low number of patients. Multicentered clinical trials are necessary to investigate these drugs.

Nebulized pentoxifylline for prevention of bronchopulmonary dysplasia in very low birth weight infants: A pilot clinical study

OBJECTIVE

To evaluate the effectiveness of nebulized pentoxifylline (PTXF) compared to intravenous dexamethasone (DX) or placebo (nebulized distilled water) for the prevention of bronchopulmonary dysplasia (BPD).

METHODS

One hundred and fifty very low birth weight infants were randomly assigned to three groups. Entry criteria were the need for oxygen administration on the fourth day of life, irrespective of whether ventilatory support was required. PTXF was administered with a nebulizer every 6 hours on three consecutive days (a single course) in a dose of 20 mg/kg when infants were breathing spontaneously or 10 mg/kg when they needed ventilatory support. DX was given every 12 hours on three consecutive days in a dose of 0.25 mg/kg. Nebulized distilled water was administered with the schedule of inhalation as in the PTXF group. When the need for ventilatory support or oxygen dependency persisted, the course of both drugs and placebo administration was repeated every seven days until the diagnosis of BPD was established.

RESULTS

Both PTXF and DX reduced the incidence of disease when compared with placebo. The respective data obtained for the PTXF-group versus the placebo group were as follows: difference in risk, 27%; OR: 0.32; CI: 0.11-0.94; p = 0.039; whereas the results for the DX-group versus the placebo group were: difference in risk, - 23%; OR: 0.39; CI: 0.14-1.14; p = 0.07.

CONCLUSION

Our data show that nebulized PTXF reduces the risk of BPD and may be a potential alternative to steroids in the prevention of this disease.

Emerging drugs for the prevention of bronchopulmonary dysplasia

BACKGROUND

Bronchopulmonary dysplasia (BPD) is a common adverse outcome of very premature birth and is associated with chronic respiratory morbidity.

OBJECTIVE

To determine if there were preventative therapies proven safe and efficacious in appropriately powered randomised trials.

METHODS

A literature review was undertaken.

RESULTS

Systemically administered corticosteroids, if given in the first 2 weeks, do significantly reduce BPD but have serious side effects. Vitamin A also reduces BPD, but has side effects, and further investigation is needed to identify the safest dosage regimen. There are, however, promising therapies that include antioxidants, low-dose nitric oxide and methylxanthines.

CONCLUSION

Further work is necessary to identify safe and effective preventative drugs for BPD.

Effect of Pentoxifylline on inflammatory burden, oxidative stress and platelet aggregability in hypertensive type 2 diabetes mellitus patients

OBJECTIVES

Inflammation and oxidative stress are main culprits behind atherosclerosis in diabetes mellitus. This study explores the effect of add-on Pentoxifylline on inflammatory burden and oxidative stress in hypertensive diabetic patients.

RESEARCH DESIGN AND METHODS

60 hypertensive type 2 diabetic, aged > or = 45 years were evaluated for anthropometry, clinical parameters, C-reactive protein, total leukocyte count, erythrocyte sedimentation rate, serum albumin, plasma malondialdehyde, blood reduced glutathione, platelet aggregation and clot retraction profile. With informed consent and randomization, Pentoxifylline (400 mg) was prescribed to 30 patients orally twice daily with meals as add-on therapy to the standard therapeutic regimen for one month. The particular parameters were repeated in 26 patients in control group and 25 patients in Pentoxifylline group who completed the follow up. The study was a randomized, open, add-on clinical trial with parallel controls.

RESULTS

At one-month follow-up, in the Pentoxifylline group, there was 20.9% decrease (p<0.001) in C-reactive protein, 18% reduction (p<0.001) in erythrocyte sedimentation rate, 11.1% reduction (p<0.001) in total leukocyte count and 5.8% increase (p=0.003) in serum albumin. Pentoxifylline showed 20.2% reduction in plasma malondialdehyde and 4.6% increase in blood reduced glutathione level. In therapeutic dose range, Pentoxifylline exerted a significant anti-aggregatory effect and a dose dependent decrease in clot retraction in-vitro but there was no significant change in ex-vivo clot retraction. The control group showed no statistically significant change in parameters assessed.

CONCLUSION

This study reveals improvements in inflammatory markers, oxidative stress and platelet-aggregation by Pentoxifylline, thus preventing atherosclerosis in diabetes mellitus.

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.

Blocking of Akt/NF-kappaB signaling by pentoxifylline inhibits platelet-derived growth factor-stimulated proliferation in Brown Norway rat airway smooth muscle cells

The proliferation of airway smooth muscle cells (ASMC) can cause airway hyperresponsiveness (AHR). It has been reported that platelet-derived growth factor (PDGF) can stimulate the proliferation of ASMC through phosphatidylinositol 3-kinase (PI3 K) signaling pathway, which can activate Akt protein. Activated-Akt can activate downstream signal protein [p70S6 K, nuclear factor (NF)-kappaB, and extracellular signal regulated kinase (ERK)], increasing the cyclin D1 level and suppressing the transcription of p27Kip1 to enable cell cycle entry. This investigation demonstrated that pentoxifylline (PTX) inhibited the PDGF-stimulated proliferation of ASMC by suppressing activation of the Akt/NF-kappaB pathway. ASMC were treated with PTX for 48 h, which attenuated the PDGF-stimulated proliferation of ASMC. PTX and wortmannin, a PI3 K inhibitor, not only inhibited the PDGF-activated phosphorylation of Akt but also suppressed p70S6 K expression and IkappaBalpha degradation, inhibiting nuclear translocation and the DNA binding activity of NF-kappaB. However, PTX did not influence the phosphorylation of ERK1/2. The suppression of p70S6 K by rapamycin did not influence cyclin D1 expression in PDGF-stimulated cells. These data reveal that the down-regulation of the Akt/NF-kappaB signaling pathway by PTX inhibited the proliferation of ASMC. PTX may provide information on the pathogenesis of asthma.

Inhibition of tumor necrosis factor alpha signaling by anti-tumor necrosis factor alpha antibodies and pentoxifylline is unable to prevent fumonisin hepatotoxicity in mice

Fumonisin B1 (FB1), a mycotoxin from Fusarium verticillioides, disrupts sphingolipid metabolism by inhibiting ceramide synthase leading to modulation of cytokines including tumor necrosis factor (TNF) alpha. Current study investigated the effect of interrupting TNFalpha signaling, known to be involved in FB1 hepatotoxicity. Male C57BL/6N mice were injected intravenously once with anti-TNFalpha antibodies or treated with pentoxifylline at 150 mg/kg intraperitoneally twice a day for 5 days to inhibit TNFalpha production before and during subcutaneous injection of 2.25mg FB1/kg daily for 5 days; mice were sampled one day after the last treatment. Results showed that both anti-TNFalpha antibodies and pentoxifylline did not prevent FB1 hepatotoxicity; the latter was somewhat augmented, indicated by increases in circulating alanine aminotransferase and aspartate aminotransferase, and incidence of apoptotic hepatocytes. Anti-TNFalpha antibodies did not alter FB1-induced accumulation of free sphingoid bases or expression of TNFalpha in liver following the FB1 treatment. Pentoxifylline significantly reduced accumulation of free sphinganine and expression of TNFalpha. Neither anti-TNFalpha antibodies nor pentoxifylline altered FB1-induced expression of interleukin-12, interferongamma, lymphotoxinbeta, and c-myc. Expression of c-myc, an inducer of cell death, increased after interference with TNFalpha signaling. These findings suggest a dual role of TNFalpha signaling activation in FB1 hepatotoxicity.

Antiinflammatory Therapies for Cystic Fibrosis: Past, Present, and Future

Inflammation is a major component of the vicious cycle characterizing cystic fibrosis pulmonary disease. If untreated, this inflammatory process irreversibly damages the airways, leading to bronchiectasis and ultimately respiratory failure. Antiinflammatory drugs for cystic fibrosis lung disease appear to have beneficial effects on disease parameters. These agents include oral corticosteroids and ibuprofen, as well as azithromycin, which, in addition to its antimicrobial effects, also possesses antiinflammatory properties. Inhaled corticosteroids, colchicine, methotrexate, montelukast, pentoxifylline, nutritional supplements, and protease replacement have not had a significant impact on the disease. Therapy with oral corticosteroids, ibuprofen, and fish oil is limited by adverse effects. Azithromycin appears to be safe and effective, and is thus the most promising antiinflammatory therapy available for patients with cystic fibrosis. Pharmacologic therapy with antiinflammatory agents should be started early in the disease course, before extensive irreversible lung damage has occurred.

Pentoxifylline does not improve outcome in a murine model for the multiple-organ dysfunction syndrome

OBJECTIVE

To investigate the effects of pentoxifylline (PTX) administration in a murine model for the multiple-organ dysfunction syndrome (MODS).

DESIGN AND SETTING

Prospective double-blind randomized animal study in a university research laboratory.

INTERVENTIONS AND MEASUREMENTS

Sixty C57BL/6 mice were given an aseptic intraperitoneal injection of lipopolysaccharide followed after 6 days by zymosan (day 0) at a dose of either 0.9 or 1.0 mg/g body weight. Starting on day 0 mice were administered PTX at a dose of 80 mg/kg body weight or saline per os every 8 h. On day 17 surviving animals were killed, and their liver, lungs, spleen, and kidneys were collected.

RESULTS

Mortality, course of body temperature, body weight, and macroscopic lung damage were similar between zymosan-treated groups. Administration of PTX did not significantly alter survival, body temperature, body weight, or macroscopic lung damage. In addition, there were no significant differences in organ weights between mice that received PTX and mice that received PBS. Although PTX inhibited the lipopolysaccharide-induced increase in tumor necrosis factor alpha and interleukin 6 expression (but not interleukin 1beta expression) at both mRNA and protein level in a murine macrophage cell line, tumor necrosis factor alpha mRNA expression in the livers of PTX-treated mice was not significantly inhibited.

CONCLUSIONS

The results reported here do not support the hypothesis that PTX improves outcome in zymosan-induced multiple-organ dysfunction in mice.

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.

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.

In vitro pharmacoregulation of CC chemokine ligand 5 and its receptor CCR5 in diffuse lung diseases

BACKGROUND

CC chemokine ligand (CCL)5 and its receptor CCR5 contribute to leukocyte migration into lungs of patients with diffuse lung diseases (DLD). Pharmacological regulation of CCL5 and CCR5 expression was therefore explored in bronchoalveolar cells obtained from patients with DLD.

METHODS

Cells from 21 patients were co-cultivated in vitro with tumour necrosis factor-alpha and dexamethasone, cyclosporin A (CyA) or pentoxifylline. Chemokine mRNA expression and protein production was assessed by reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay, respectively.

RESULTS

Dexamethasone altered CCL5 mRNA expression and suppressed its protein levels. CyA inhibited chemokine mRNA expression but not protein production. Pentoxifylline did not affected chemokine expression. Both dexamethasone and CyA suppressed CCR5 mRNA transcripts.

CONCLUSION

In conclusion, while dexamethasone downregulates the CCL5 functional form, CyA and pentoxifylline have no effects on CCL5 protein. These data provide in vitro correlation for clinical applications of immunomodulators in therapy of DLD.

Prophylactic anti-inflammation inhibits cigarette smoke-induced emphysema in guinea pigs

In this study, the effect of prophylactic anti-inflammation on the development of smoke-induced emphysema was investigated. Young male guinea-pigs aged 1.5-2 months (weighing 198.3+/-26.9 g) were randomly divided into 4 groups: group A (cigarette smoke exposure only), group B (cigarette smoke exposure plus pentoxifylline-rich (PTX, 10 mg/d) forage feeding), group C (cigarette smoke exposure plus intermittent cortical steroid injection (Triamcinolone acetonide, 3 mg, i.m., every three weeks) and control group (group D: animals with sham smoke exposure, raised under the same conditions). Animals in group A, B and C were exposed to smoke of cigarettes for 1 to 1.5 h twice a day, 5 days a week. All animals were killed at the 16th week and followed by morphometrical analysis of the midsagittal sectioned lung slices. Smoke exposure of 16 weeks resulted in visible emphysematous development in Group A but not in Group B and C. It was evidenced by the indicator of air-space size, mean linear intercept (Lm): 120.6+/-16.0 microm in Group A; 89.8+/-9.2 microm in Group B and 102.4+/-17.7 microm in Group C. The average Lm in either group B or group C was shorter than that in Group A (ANOVA and Newman-Keuls test, F=8.80, P=0.0002) but comparable to that (94.8+/-13.2 microm) in group D (P>0.05). It is concluded that long-term prophylactic anti-inflammation inhibits pulmonary emphysema induced by cigarette smoking in the guinea pigs.

Immunopharmacological potential of selective phosphodiesterase inhibition. I. Differential regulation of lipopolysaccharide-mediated proinflammatory cytokine (interleukin-6 and tumor necrosis factor-alpha) biosynthesis in alveolar epithelial cells

In an attempt to elaborate in vitro on a therapeutic strategy that counteracts an inflammatory signal, we previously reported a novel immunopharmacological potential of glutathione, an antioxidant thiol, in regulating inflammatory cytokines. In the present study, we investigated the hypothesis that selective regulation of phosphodiesterases (PDEs), a family of enzymes that controls intracellular cAMP/cGMP degradation, differentially regulates proinflammatory cytokines. Selective PDE1 inhibition (8-methoxymethyl-3-isobutyl-1-methylxanthine) blockaded lipopolysaccharide-endotoxin (LPS)-mediated biosynthesis of interleukin (IL)-6, but this pathway had no inhibitory effect on tumor necrosis factor-alpha (TNF-alpha). Furthermore, inhibition of PDE3 (amrinone) abolished the effect of LPS on IL-6, but attenuated TNF-alpha production. Reversible competitive inhibition of PDE4 (rolipram) exhibited a potent inhibitory effect on IL-6 and a dual, biphasic (excitatory/inhibitory) effect on TNF-alpha secretion. Blockading PDE5 (4-[[3',4'-(methylenedioxy)benzyl] amino]-6-methoxyquinazoline) showed a high potency in reducing IL-6 production, but in a manner similar to the inhibition of PDE4, exhibited a biphasic effect on TNF-alpha biosynthesis. Simultaneous inhibition of PDE5, 6, and 9 (zaprinast), purported to specifically elevate intracellular cGMP, reduced, in a dose-independent manner, IL-6 and TNF-alpha biosynthesis. Finally, nonselective inhibition of PDE by pentoxifylline suppressed LPS-mediated secretion of IL-6 and TNF-alpha. The involvement of specific PDE isoenzymes in differentially regulating LPS-mediated inflammatory cytokine biosynthesis indicates a novel approach to unravel the potential therapeutic targets that these isozymes constitute during the progression of inflammation within the respiratory epithelium.

Differential effects of pentoxifylline on the hepatic inflammatory response in porcine liver cell cultures. Increase in inducible nitric oxide synthase expression

Pentoxifylline (PTX) has been shown to exert hepatoprotective effects in various liver injury models. However, little information is available about the effect of PTX on the hepatic acute phase response. In the present study, the effect of PTX on a lipopolysaccharide (LPS)-induced acute phase response in primary porcine liver cell cultures was examined. During 72 hr of incubation with or without LPS, the ability of PTX to influence the secretion of tumour necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), acute phase proteins, and nitric oxide (NO) was assessed. PTX completely inhibited LPS-induced TNF-alpha production and attenuated IL-6 only after 48 hr of incubation. In contrast, PTX potentiated NO production and the expression of inducible nitric oxide synthase (iNOS) in hepatocytes after stimulation with LPS. The increased expression of iNOS and concurrent production of NO was also observed when liver cell cultures were incubated with dibutyryl cyclic adenosine monophosphate. No effect of PTX on acute phase protein secretion was observed during 72 hr of incubation. The present results show that PTX differentially affects the endotoxin-induced inflammatory response in primary porcine liver cell cultures by suppressing TNF-alpha and IL-6 while potentiating NO production.

Isolation of a lactose-binding protein with monocyte/macrophage chemotactic activity. Biological and physicochemical characteristics

BACKGROUND

We established a T cell line, STO-5, which constitutively produced monocyte/macrophage chemotactic activity via human T cell lymphoma-leukemia-virus-induced transformation of normal human T cells.

METHODS

We isolated and purified a lactose-binding protein, MCF-pl5-L (MW of about 50 kD, pl of about 5) from a conditioned medium of STO-5. By using highly purified MCF-pl5-L, its biological and physicochemical properties were elucidated in comparison with C5a and MCP-1.

RESULTS

MCF-pl5-L exhibited an evident dose-dependent monocyte chemotactic activity (MCA). MCF-pl5-L had no or little affinity for heparin unlike chemokines such as MCP-1. We further found that MCF-pl5-L exhibited potent chemotactic activity not only for monocytes but also for alveolar macrophages. In contrast, C5a and MCP-1 failed to show evident chemotactic activity for alveolar macrophages though they did show MCA. MCF-pl5-L failed to exhibit evident eosinophil and neutrophil chemotactic activities, indicating its chemotactic activity is selective for monocytes/macrophages. Regarding the biological functions of MCF-pl5-L other than MCA and chemotactic activity for alveolar macrophages, we found that MCF-pl5-L but not C5a and MCP-1 could prolong the life span of alveolar macrophages, probably by inhibiting apoptosis of macrophages, and stimulate the production of TNF-alpha from macrophages.

CONCLUSIONS

These results suggest that MCF-pl5-L plays a role as an immune modulator for monocytes/macrophages in the site.