Interleukin-15 is a new cytokine that stimulates the proliferation of T cells and other cells of the immune system. Some of the biological properties of interleukin-15 overlap that of interleukin-2. ...Using murine models, the present studies have shown that interleukin-15,
in vivo, is three to four times more potent than interleukin-2 in generating cytolytic effector splenocytes that lyse YAC target cells. It is approximately one-third as potent as interleukin-2 in inducing specific cytolytic cells that lyse allogeneic target cells. Interleukin-15 is approximately half as potent as interleukin-2 in suppressing pulmonary metastasis induced by MCA-205 tumor cells. The dose of interleukin-15 required to induce pulmonary vascular leak in mice is six times higher than that required for interleukin-2. These results support the view that interleukin-15 exhibits a therapeutic index that is superior to interleukin-2.
Pulmonary vascular leak induced in mice by interleukin 2 (IL-2) was attenuated by pretreatment with single or multiple doses of oral methotrexate. Methotrexate also attenuated pulmonary vascular leak ...when either larger doses of IL-2 or when lymphokine-activated killer (LAK) cells or LAK cells plus IL-2 were administered. Lymphoid infiltrates in the lungs of mice treated with IL-2 and methotrexate were significantly lower. The number of mice surviving treatment with high doses of IL-2 was also significantly increased when these mice were treated with methotrexate. Methotrexate prevented the IL-2-induced increase in the number of splenocytes that were asialo GM1+ but had no effect on Lyt 2+ or L3T4+ cell content. A marginal but significant inhibition in the generation of effector splenocytes that were cytolytic to either YAC or MCA-205 tumor targets was observed in mice treated with methotrexate and IL-2. In vivo studies indicated that methotrexate did not compromise the anti-tumor efficacy of treatment regimens that contained IL-2, LAK cells, or IL-2 and LAK cells. These results demonstrate the potential clinical utility of methotrexate in attenuating pulmonary vascular leak induced by IL-2 without compromising its efficacy. One potential mechanism of action of methotrexate is related to its ability to stimulate the release of adenosine followed by the inhibition of the adhesion of leukocytes to the IL-2-activated endothelium.
A series of bis-aryl amide (13-57 and 66-81) and bis-aryl urea (58 and 85) antagonists of platelet-activating factor (PAF) was prepared that contain, separating the two aromatic rings, linear amide ...linkages of the form -(CH2)nCONH- (n = 0-2), -OCH2CONH-, and -(CH2)nNHCO- (n = 0-1), branched amide linkages of the form -(CH2)nN(COR)- (n = 1-3, R = CH3 or n-C3H7), and -N(COCH3)CH2-, and urea linkages of the form -NHCONH- and -CH2N(CONHCH3)-. These compounds were examined for their ability to inhibit PAF-induced platelet aggregation of rabbit platelets. These in vitro data were compared to similar data obtained for a number of known PAF antagonists. The compounds were evaluated in vivo, in the mouse, for their ability to prevent death induced by a lethal challenge of PAF. The relationships between the biological activity and the nature, lipophilicity, and position of substituents of the aromatic rings were studied. Best activity was observed for compounds having linkages of the type -CH2CONH-, -CH2N(COR)-, and -CH2NHCO-. Many of these compounds inhibit PAF-induced platelet aggregation with IC50's under 1 microM.
A series of platelet activating factor (PAF) antagonists containing a quaternary pyridinium ring connected through an amide, imide, or carbamate linkage to a substituted aromatic ring was prepared. ...Of these compounds, those containing a branched imide linkage of the form (CON-(COCH3)CH2, 37-51, and 59) generally showed excellent PAF antagonist properties in vitro. Structure-activity relationships within this series of compounds were studied extensively with respect to substituents and the position of substitution in both the aromatic and pyridinium rings. Several of these compounds (40 and 44) showed in vitro PAF antagonism at less than 0.1 microM and are as potent as CV-6209, the most potent PAF antagonist reported in the literature. Less active PAF antagonists were those bearing simple amide linkages (20-23, 27-29, and 31-35), linear imide linkages (62-63), or carbamate linkages (66 and 68), between the two aromatic rings. A number of our PAF antagonists were tested in vivo in mice and rabbits for their ability to protect these animals against a lethal injection of PAF. Those antagonists that are particularly potent (IC50 < 0.1 microM) provide excellent protection against an LD97 dose of PAF in rabbits. The relationships between structure and activity in vitro and in vivo are presented and compared to literature standards.
In murine models of endotoxemia, large amounts of lipopolysaccharide have to be administered to induce mortality. If mice are pretreated with D-galactosamine, the amount of lipopolysaccharide ...required to induce mortality is significantly lowered. Pluronic F 127 liquid is a relatively non-toxic copolymer that exhibits reverse gelation properties. Thus, it is a liquid at cold temperature and a gel at body temperature. The present studies were performed to ascertain whether the reverse gelation properties of Pluronic F 127 liquid could be used in devising a model of septic shock where a sustained delivery of lipopolysaccharide occurred. In evaluating this model, dose-response studies were conducted with lipopolysaccharide when a) it was administered intraperitoneally in saline or in Pluronic F 127 liquid, and b) it was administered intravenously to mice that had been pretreated with saline or Pluronic F 127 liquid. Mortality was followed for up to 72 hrs.
Various doses of Escherichia coli lipopolysaccharide dissolved in saline or in Pluronic F 127 liquid were administered intraperitoneally to mice. The lethal dose of lipopolysaccharide required to kill 50% of the mice (LD50) administered in Pluronic F 127 liquid was approximately ten- to 15-fold less than the values obtained for lipopolysaccharide administered in saline. This decrease in the LD50 of lipopolysaccharide was also observed if the mice were treated intraperitoneally with Pluronic F 127 liquid and challenged 6 hrs later with iv lipopolysaccharide. The concentrations of tumor necrosis factor and interleukin-6 in the plasma were significantly higher when a low dose of lipopolysaccharide was administered to mice that had been pretreated with Pluronic F 127 liquid. While there was no effect on the liver enzymes, Pluronic F 127 liquid caused an increase in the plasma triglycerides.
The data reported in this paper indicate that the LD50 of lipopolysaccharide is significantly decreased if it is administered in Pluronic F 127 liquid or administered to mice that have been pretreated with the Pluronic F 127 liquid. Thus, Pluronic F 127 liquid appears to sensitize mice to low levels of lipopolysaccharide. Unlike the D-galactosamine model, lipopolysaccharide can be administered as late as 6 hrs after treatment with Pluronic F 127 liquid. While the mechanisms by which Pluronic F 127 liquid sensitizes mice is not known, plasma triglycerides were increased in mice treated with this agent, suggesting that tissues responsible for the synthesis and/or degradation of triglycerides play a role in this sensitization process.
With the use of the human basophil histamine release assay, 5-aryl-2-amino1,2,4triazolo1,5-cpyrimidines were found to be active as mediator release inhibitors. These compounds were prepared by ...reacting arylamidines with sodium ethyl formylacetate or with ethyl propiolate to give pyrimidinones. Treatment with phosphorus oxychloride gave a chloropyrimidine, which was converted to a hydrazinopyrimidine with hydrazine. Cyclization, using cyanogen bromide, gave the triazolo1,5-cpyrimidines, after a Dimroth rearrangement. Following a structure-activity evaluation, the 5-3-(trifluoromethyl)phenyl-2-amino (8-10), 5-(3-bromophenyl)-2-amino (8-13), 5-3-(difluoromethoxy)-phenyl-2-amino (8-11), and 5-(4-pyridinyl)-2-amino (6-7) compounds were found to have the best activity. They were chosen for further pharmacological and toxicological study.
By using inhibition of histamine release from antigen-challenged, sensitized human basophils as a means of identifying a potentially prophylactic drug for the treatment of asthma, a series of ...substituted imidazo1,5-d1,2,4triazines were found, which were active. These compounds were prepared by treating imidazolecarboxaldehydes with excess Grignard agent and then oxidizing the resulting alcohols to ketones with Jones reagent. Pyrolysis of a mixture of ketone and methyl carbazate at 200 degrees C in diphenyl ether produced the desired imidazo1,5-d1,2,4triazines. Those compounds with the greatest basophil activity were tested for in vivo activity in the mouse passive cutaneous anaphylaxis (PCA) and the guinea pig passive anaphylaxis tests. The best compounds, 1-ethyl-8-methyl-6-propylimidazo1,5-d1,2,4triazin-4(3H)- one (4-17) and 1,8-dimethyl-6-propylimidazo1,5-d1,2,4triazin-4-(3H)-one (4-16) were chosen for further study.
The role of immunologically released mediators, such as histamine, leukotrienes, and platelet-activating factor, is well-established for asthma and other allergic disorders. Developing therapeutic ...agents which would block mediator release from mast cells and other relevant cell types would provide a rational approach to asthma therapy. Using human basophil as a screen, a series of 4-aryl-2-(phenylamino)pyrimidines was found which inhibited mediator release. These compounds were prepared by condensing acetyl heterocycles with dimethylformamide dimethyl acetal to form enaminones which are cyclized with aryl guanidines to give pyrimidines. After examining a large number of analogs, N-3-(1H-imidazol-1-yl)phenyl-4-(2-pyridinyl)-2- pyrimidinamine (1-27) was chosen for toxicological evaluation.
Experiments using a murine model of heat-killed Staphylococcus aureus-induced gram-positive bacterial sepsis indicate that the lethal bacterial effects can be prevented if mice are pretreated with CL ...184,005, a platelet-activating factor (PAF) antagonist. CL 184,005 was ineffective when administered after bacterial challenge. Plasma of mice pretreated with CL 184,005 contained significantly less tumor necrosis factor (TNF), suggesting that CL 184,005 interferes with TNF synthesis induced by S. aureus. Spleen-associated TNF protein was also decreased by pretreatment with CL 184,005. Although TNF levels were significantly decreased in mice treated with CL 184,005, interleukin-6 levels in serum were significantly increased. Athymic mice were also susceptible to the lethal effects of S. aureus, suggesting that T cells were not involved. When rats rendered hypotensive with S. aureus were treated with CL 184,005, their blood pressure was normalized. Mice treated with enterotoxin B were not protected if they were pretreated with CL 184,005; however, TNF levels in these mice were significantly lower, suggesting that mediators other than PAF and TNF may contribute to the lethal effects of enterotoxin.
Experiments using a murine model of heat-killed Staphylococcus awra/s-induced gram-positive bacterial sepsis indicate that the lethal bacterial effects can be prevented if mice are pretreated with CL ...184,005, a platelet-activating factor (PAF) antagonist. CL 184,005 was ineffective when administered after bacterial challenge. Plasma of mice pretreated with CL 184,005 contained significantly less tumor necrosis factor (TNF), suggesting that CL 184,005 interferes with TNF synthesis induced by S. aureus. Spleen-associated TNF protein was also decreased by pretreatment with CL 184,005. Although TNF levels were significantly decreased in mice treated with CL 184,005, interleukin-6 levels in serum were significantly increased. Athymic mice were also susceptible to the lethal effects of S. aureus, suggesting that T cells were not involved. When rats rendered hypotensive with S. aureus were treated with CL 184,005, their blood pressure was normalized. Mice treated with enterotoxin B were not protected if they were pretreated with CL 184,005; however, TNF levels in these mice were significantly lower, suggesting that mediators other than PAF and TNF may contribute to the lethal effects of enterotoxin.
