Effect Of Lisofylline Research Articles

In vitro effect of pentoxifylline and lisofylline on deformability and aggregation of red blood cells from healthy subjects and patients with chronic venous disease.

Purpose. The aim of the study was to assess the in vitro potency of pentoxifylline (PTX) and one of its most active metabolites lisofylline (LSF) to improve rheological properties of red blood cells (RBC) from healthy individuals and patients with chronic venous disease (CVD). Additionally, the study aimed to compare the effects of PTX and LSF on RBC deformability and aggregation. Methods. Blood samples were collected from healthy volunteers (antecubital vein) and from CVD patients (varicose and antecubital vein). Deformability and aggregation of RBC were assessed using Laser-assisted Optical Rotational Cell Analyser (LORCA). Results. PTX and LSF increased RBC elongation significantly. Additionally, RBC incubation with PTX resulted in a marked decrease in RBC aggregation. PTX reduced the tendency towards the formation of RBC aggregates and of their stability. The beneficial effect of PTX on RBC aggregation was most apparent for those cells whose aggregation tendency and aggregate stability was the greatest. Conclusions. In vitro addition of PTX or LSF effectively increased deformability of RBC from healthy donors and patients with CVD. Thus, LSF may contribute to the in vivo hemorheological effects of pentoxifylline. On the other hand, there was no significant effect of LSF on aggregation of RBC in vitro. Hence, LSF has no contribution to this particular effect of PTX. Additionally, the present study demonstrated the use of RBC with impaired deformability and aggregation for the evaluation of in vitro rheological activity of xenobiotics.

Lisofylline, a novel anti-inflammatory agent, enhances glucose-stimulated insulin secretion in vivo and in vitro: studies in prediabetic and normal rats

Previous studies from this laboratory have shown that the novel anti-inflammatory agent, lisofylline (LSF), improves oral glucose tolerance in streptozotocin (STZ) diabetic rats. Subsequent studies suggested that the improved glucose tolerance could be the result of enhanced β-cell functioning. The possibility that LSF enhancement of insulin release in these animals is the result of direct effects of this agent on a residual population of functionally normal β cells was further evaluated in these studies. In vivo studies: 6- to 8-week-old male rats were administered STZ (35 mg/kg body weight) intravenously. After 10 days, LSF administration (25 mg/kg body weight, twice daily) was initiated in the treated group (n = 11) for comparison with the vehicle-injected controls (n = 10). Body weight, food intake, and serum glucose and insulin levels were monitored weekly. Glucose and insulin responses to an oral glucose bolus were measured at 4 to 5 weeks as an index of LSF effects on impaired glucose tolerance. Glucose areas under curve (AUC) during the 2-hour tolerance tests in the LSF-treated rats (n = 11) were 23,390 ± 253 versus 29,390 ± 1,006 mg/dL × min ( P < .0001) in the vehicle-injected rats (n = 10). Improved glucose tolerance was associated with increases in blood insulin levels in the LSF-treated rats, AUC (+LSF) = 6,564 ± 66 versus 5,127 ± 633 μU/mL × min in the vehicle-injected STZ-rats (not significant [NS]). These observations suggested that the improved glucose tolerance is the result of direct effects of LSF on glucose-induced release of insulin. In vitro studies: the validity of this hypothesis was subsequently tested using isolated perfused pancreas preparations from normal rats. In this series of experiments, 12-week-old animals were used, and pancreases were perfused in situ using single-pass technique. Three levels of LSF were directly infused into individual pancreas preparations and included 20 (n = 5), 40 (n = 4), and 60 (n = 4) μmol/L. First (minutes 3 to 10) and second (minutes 13 to 35) phase glucose-stimulated (300 mg/dL) insulin response areas (AUC) for the 2 phases measured in the LSF-infused pancreases were compared with AUC in vehicle-infused pancreases (n = 4). At LSF concentrations of 20 and 40 μmol/L, total insulin released during the first phase of glucose stimulation was more than twice that of the controls (3,919 ± 739 and 3,643 ± 630 μU, respectively v 1,481 ± 269 μU, P < .03). A total of 60 μmol/L LSF did not significantly enhance first phase glucose-induced insulin secretion. Second phase comparisons of total insulin released in the LSF-infused versus the controls showed differences of comparable magnitude (about 2-fold) with statistical significance ( P < .03) observed at all 3 levels of LSF. These findings demonstrate that LSF enhances glucose-stimulated insulin release in vitro. Enhanced β-cell functioning by LSF likely represents an important factor underlying improved glucose tolerance in vivo. In addition, the in vitro observations in normal rat pancreas indicate that the LSF effect is not limited to β-cell dysfunction per se. These results support the conclusion that agents, such as LSF, may have therapeutic benefits in type 2 diabetes.

The novel anti-inflammatory agent lisofylline prevents autoimmune diabetic recurrence after islet transplantation.

Pancreatic islet transplantation has become a promising treatment for type 1 diabetes. However, autoimmune reactivity destroys engrafted islets in type 1 diabetic recipients. The authors' previous studies demonstrated that a novel anti-inflammatory agent, lisofylline (LSF), suppressed autoimmune reactivity and protected nonobese diabetic (NOD) mice from diabetes. In this study, the authors investigated the potential of LSF in preventing autoimmune diabetes recurrence after islet transplantation. Spontaneously diabetic NOD mice received NOD severe combined immunodeficiency islet transplants and were treated with daily LSF injections at 50 mg/kg for 3 weeks. Blood glucose levels were monitored. Serum cytokine levels were measured at 1 and 3 weeks after engraftment. Nephrectomy of the islet-implanted kidney was performed in LSF-treated recipients. Histology of islet grafts was assessed at the end of the study. The effect of LSF on beta-cell function was studied in vitro. Without immunosuppressants and insulin, the LSF-treated recipient mice maintained euglycemia significantly longer than the saline-treated recipients (mean, >65 days in the LSF-treated group vs. 6 days in saline controls; P=0.0004). Serum levels of interferon-gamma were markedly reduced in LSF-treated recipients at 1 and 3 weeks posttransplant. Diabetes recurred in the LSF-treated recipients after removing the islet-implanted kidneys. Immunohistochemistry showed retention of insulin-positive cells in the grafts of the LSF-treated recipients. LSF preserved beta-cell insulin secretory function in the presence of inflammatory cytokines in vitro. This study demonstrates that autoimmune diabetes recurrence after islet transplantation could be prevented by treatment with LSF. LSF and its analogues may have the potential to prevent islet autoimmune destruction in clinical transplantation.

The novel anti-inflammatory compound, lisofylline, prevents diabetes in multiple low-dose streptozotocin-treated mice.

Proinflammatory cytokines play an important role in the development of type 1 diabetes. Lisofylline (LSF) is a novel anti-inflammatory compound that specifically inhibits proinflammatory cytokine production and action. To investigate the effect of LSF on diabetes prevention. A mouse with diabetes induced by multiple low doses of streptozotocin (STZ) can be used as an animal model for type 1 diabetes. In this study, we used this method to induce diabetes in C57BL/6J mice. The daily LSF treatment started 5 days before STZ injections and lasted for 2 weeks. The incidence of diabetes was monitored. Insulin secretion was assessed in pancreatic islets isolated from experimental mice. Cytokine production was measured in mouse sera. Islet apoptosis was assessed quantitatively. In LSF-treated mice, there was a significant reduction of diabetes incidence (25% vs. 91.6%). This protection was associated with suppression of systemic levels of IFN-gamma and TNF-alpha, inhibition of macrophage infiltration in islets, restoration of islet insulin secretion, and reduction of beta-cell apoptosis. This study suggests that treatment with LSF suppresses proinflammatory cytokines and protects beta-cells from inflammation. LSF may be useful for prevention of type 1 diabetes and other disorders associated with excessive proinflammatory cytokines.

Lisofylline, a novel antiinflammatory agent, protects pancreatic beta-cells from proinflammatory cytokine damage by promoting mitochondrial metabolism.

Proinflammatory cytokine-mediated pancreatic beta-cell dysfunction is a key pathological event in type I diabetes mellitus. Lisofylline (LSF), an anti-inflammatory agent, has been shown to protect pancreatic islets from IL-1 beta-induced inhibitory effects on insulin release. However, the mechanism of LSF action is not known. Increasing evidence suggests that the mitochondria play an important role in regulating the beta-cell insulin release capacity and the control of cellular viability. To examine the direct effects of LSF on beta-cells, insulin-secreting INS-1 cells were exposed to a combination of recombinant IL-1 beta, TNF alpha, and IFN gamma with or without LSF for 18 h. Basal and glucose-stimulated static insulin release were measured using RIA. INS-1 cell viability was determined using in situ terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling and LIVE/DEAD dual fluorescence labeling. To evaluate INS-1 mitochondrial function, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) metabolism, change in mitochondrial membrane potential, and intracellular ATP levels were assessed. Cytokine addition reduced basal (7.8 +/- 0.30 vs. 10.0 +/- 0.46 ng/ml.h; P < 0.005), glucose-stimulated insulin secretion (11.6 +/- 0.86 vs. 17.4 +/- 1.86 ng/ml.h; P < 0.005), and MTT metabolism in INS-1 cells. Over 40% of the cytokine-treated beta-cells exhibited nuclear DNA breakage, whereas the control cell death rate remained at 1-2%. Simultaneous application of LSF and cytokines to INS-1 cells restored insulin secretion, MTT metabolism, mitochondrial membrane potential, and cell viability to control levels. LSF increased beta-cell MTT metabolism as well as insulin release and glucose responsiveness. In summary, proinflammatory cytokines lead to a reduction of glucose-induced insulin secretion, mitochondrial activity, and viability in INS-1 cells. LSF at concentrations achievable in vivo protected beta-cells from the cytokine effects. The mechanism of LSF-induced protection may be by promoting mitochondrial metabolism.

Selective Downregulation of Neutrophils by a Phosphatidic Acid Generation Inhibitor in a Porcine Sepsis Model

Effects of lisofylline (1-(5-R-hydroxyhexyl)-3,7-dimethylxanthine), a functional inhibitor of phosphatidic acid (PA) generation derived fromde novosynthesis, on neutrophil function were examined in a porcine sepsis model. Hanford minipigs (18–25 kg) were randomly separated into six groups of six animals each: (1) saline control group; (2) sepsis control group, infused withPseudomonas aeruginosa(1 × 106colony-forming units/kg/min) for 2 h; (3) lisofylline control group, given a 25 mg/kg bolus of lisofylline 30 min prior to time zero, followed by a continuous infusion of 10 mg/kg/h throughout the study; (4) lisofylline pretreatment sepsis group, given lisofylline 30 min prior to sepsis, (5) lisofylline 1-h post-treatment sepsis group, and (6) lisofylline 2-h post-treatment sepsis group. All animals were studied for 6 h. Neutrophils were isolated at −0.5, 2, and 6 h. In the pretreatment and 1-h post-treatment groups, sepsis-induced neutrophil attachment to fibronectin was significantly attenuated. Sepsis-enhanced phagocytic activity was significantly reduced in the lisofylline pretreatment sepsis group, but not in the post-treatment groups. No treatment affected phorbol 12-myristate 13-acetate-induced chemiluminescence and basal filamentous actin content, which increased in sepsis, and cap formation, which declined in sepsis. Sepsis caused neutropenia, pretreatment produced neutrophilia, and 1-h post-treatment caused the neutropenia to recover to control levels. Interestingly, toward the end of the 6-h period, the neutrophil count was higher in the lisofylline control group than in the saline control groups. Thus, the inhibition of PA generation fromde novosynthesis during sepsis not only can selectively downregulate some neutrophil functions but can also reverse neutropenia.

Lisofylline as an adjuvant to high dose cytotoxic therapy

Lisofylline, a dimethylxanthine derivative, has been shown to block the induction of hematopoietic growth inhibitors produced in response to cytotoxic anticancer therapy. In the current study, mice bearing established EMT-6 mammary carcinoma were treated with high dose cyclophosphamide, melphalan, BCNU, 5-fluorouracil or with total body radiation alone or with peripheral blood cells. The effect of lisofylline and/or G-CSF on leukocyte recovery was examined. Lisofylline was as effective as G-CSF in accelerating the recovery of white blood cells and granulocytes after treatment with high dose chemotherapy or total body radiation. Lisofylline alone or along with G-CSF was effective in protecting animals from the weight loss caused by high dose melphalan but not from weight loss caused by other cytotoxic therapies. Administration of lisofylline did not alter the killing of bone marrow CFU-GM by single doses of cyclophosphamide, melphalan or BCNU. However, administration of lisofylline increased the killing of EMT-6 tumor cells taken from the same animals. Administration of lisofylline had no effect on EMT-6 tumor growth. However, treatment with lisofylline along with high dose cyclophosphamide: melphalan, BCNU or 5-fluorouracil significantly increased the tumor growth delay produced by these agents. Overall, in the high dose therapy/EMT-6 mammary carcinoma model, lisofylline selectively enhanced hematopoietic recovery and increased tumor response to cytotoxic therapy.

Effect of lisofylline and pentoxifylline on the bacterial-stimulated production of TNF-alpha, IL-1 beta IL-10 by human leucocytes.

The present study concerns the effect of the xanthine derivates lisofylline (LSF) and pentoxifylline (PTX) on the production of pro-inflammatory cytokines tumour-necrosis factor-alpha (TNF-alpha) and interleukin-1 beta (IL-1 beta) and the de-activating cytokine interleukin-10 (IL-10) by human leucocytes during stimulation with lipopolysaccharide (LPS), heat-killed Gram-negative bacteria (GNB) or Gram-positive bacteria (GPB). The production of TNF-alpha and IL-1 beta by leucocytes stimulated with LPS, Haemophilus influenzae type b (Hib) or Streptococcus pneumoniae was inhibited by both drugs. The production of IL-10 by leucocytes stimulated with LPS and Hib was inhibited by both xanthine derivates only at 48 hr. However, incubation of leucocytes with S. pneumoniae in the presence of LSF or PTX stimulated the production of IL-10 about four- and twofold at 24 hr and 48 hr, respectively. In all instances, the extent of inhibition or enhancement of cytokine production by LSF or PTX was equal. The divergent effects of xanthine derivates on the IL-10 production indicate the existence of distinct intracellular pathways depending on whether leucocytes are stimulated by GPB or GNB.

The effects of post-treatment with lisofylline, a phosphatidic acid generation inhibitor, on sepsis-induced acute lung injury in pigs.

The effects of lisofylline [(R)-1-(5-hydroxyhexyl)-3,7-dimethylxanthine] (LSF), an inhibitor of de novo phosphatidic acid (PA) generation, on sepsis-induced acute lung injury was studied using Hanford minipigs weighing 18 to 25 kg. Sepsis was induced by an intravenous infusion of Pseudomonas aeruginosa (1 x 10(6)/colony-forming units/kg/min over 2 h). Saline was used as the control vehicle. Six groups were studied: saline control group (SALINE: n = 5); sepsis control group (SEPSIS: n = 5); LSF control group (LSF: n = 5), which received a 25-mg/kgbolus of LSF 30 min before time zero followed by continuous infusion of 10 mg/kg/h throughout the study; LSF-treated septic groups, which were treated with LSF 30 min prior to sepsis (Pre: n = 5), 1 h postonset (Post-1 h: n = 8) or h postonset (Post-2 h: n = 8) of the bacterial infusion. Hemodynamics PaO2, neutrophil counts, and plasma porcine tumor necrosis factor-alpha concentrations were monitored for 6 h. After the minipigs were killed, lung tissue was sampled to measured wet-to-dry weight ratio (W/D), tissue albumin index (TAI), thiobarbituric acid-reactive material content (TBARM), and myeloperoxidase (MPO) activity. Compared with the SALINE group, the SEPSIS group showed significant systemic hypotension, pulmonary hypertension, arterial hypoxemia, neutropenia, and increase in TNF-alpha, MPO activity, W/D, TBARM, and TAI. LSF treatment attenuated sepsis-induced pulmonary hypertension, neutropenia, and hypoxemia, and increased MPO activity and lung injury measurements in the Pre and Post-1 h groups, but its efficacy was blunted in the Post-2 h group. Plasma TNF-alpha was decreased only in the Pre group. Thus, inhibition of intracellular PA generation through de novo pathways attenuates sepsis-induced acute lung injury.

Lisofylline, an inhibitor of unsaturated phosphatidic acid generation, ameliorates interleukin-1 beta-induced dysfunction in cultured rat islets.

Interleukin-1 beta (IL-1 beta) causes rat islet cell dysfunction through mechanisms that involve inducible nitric oxide synthase (iNOS). However, IL-1 beta also activates several lipid pathways, including those generating phosphatidic acid (PA). Lisofylline (LSF), a water-soluble, nontoxic, selective inhibitor of the PA-1 alpha subspecies, which is stimulated by IL-1 beta and tumor necrosis factor-alpha, has been shown to prevent cytokine-induced cytotoxicity in in vivo animal models. To evaluate the effect of LSF on acute IL-1 beta-induced islet dysfunction, rat islets were exposed to IL-1 beta (0.1 ng/ml) with or without LSF (100 microM) for 24 h, followed by 25 mM glucose (G) stimulation, measurement of rat insulin by RIA, and calculation of the insulin secretion rate. In other experiments, rat islets were precultured for 48 h, then treated for 48 h in 25 mM G with or without IL-1 beta (0.1 ng/ml) and LSF (400 microM), and aliquots of medium were removed at 0, 24, and 48 h for measurement of rat insulin. In addition, islets were exposed to 25 mM G with or without IL-1 beta and LSF, lipids were then extracted, and PA subspecies were identified by TLC and mass spectroscopy, and quantitated using normal phase HPLC. Islets were also exposed to IL-1 beta with or without LSF, and Western immunoblots were performed to evaluate the effect of LSF on iNOS protein expression. IL-1 beta caused a 44% decrease in islet G-stimulated insulin secretion compared to that in untreated islets (P < 0.0005), which was totally reversed by LSF. In addition, IL-1 beta decreased the G-stimulated medium insulin content by 75% at 24 h (P = 0.0004) and 86% at 48 h compared to that in control islets (P < 0.0001). LSF-treated islets maintained 70% of medium insulin content at 24 h (P = 0.11) and 50% at 48 h (P < 0.0001) compared to control islets. HPLC quantitation of PA-1 alpha extracted from islets treated with IL-1 beta alone showed an approximately 15-fold increase over the PA-1 alpha content of islets treated with IL-1 beta and LSF. IL-1 beta-induced expression of iNOS was unchanged with the addition of LSF. These results suggest that LSF is effective in reducing IL-1 beta-induced islet dysfunction, thus supporting the role of lipid mediators such as PA in cytokine-induced islet toxicity.