Comparative in vitro and in vivo activities of two 9-deazaguanine analog inhibitors of purine nucleoside phosphorylase, CI-972 and PD 141955

An in-parallel comparison is presented of the in vitro and in vivo properties of two 9-deazaguanine analog inhibitors of purine nucleoside phosphorylase (PNP), CI-972 [8-amino-9-deaza-9-(3-thienylmethyl)guanine] and PD 141955 [9-deaza-9-(3-thienylmethyl)guanine] (published Ki values of 0.83-8.0 and 0.08 microM, respectively). Despite structural similarities, PD 141955 was considerably more potent and active in all systems studied. The respective IC50 values for inhibition of MOLT-4 cell growth in the absence and presence of 10 microM 2'-deoxyguanosine (GdR) were greater than 50 and 5.06 microM for CI-972 and 15.4 and 0.061 microM for PD 141955. PD 141955 induced accumulation of dGTP in GdR-treated MOLT-4 and CEM cells at log-lower concentrations than were required of CI-972, and the magnitude of dGTP accumulation in PD 141955-treated T cell cultures was markedly greater (e.g. 366 vs 100 pmol/10(6) CEM cells at 10 microM). PD 141955 administered orally produced a dose-dependent elevation of plasma inosine and guanosine in rats over a broad concentration range. Mean plasma inosine concentrations following a 150 mg/kg p.o. dose peaked at 6.21 and 13.2 microM in CI-972 and PD 141955-treated rats, respectively. Low levels of inosine were detectable at 50 micrograms/kg following oral administration of PD 141955.

Differential regulation of human eosinophil, macrophage, and neutrophil functions by the allergic mediator release inhibitor CI-959

The cell activation inhibitor CI-959 [5-methoxy-3-(1-methyl-ethoxy)-N-1H- tetrazol-5-ylbenzo[b]thiophene-2-carboxamide, monosodium salt] was evaluated for its effect on the activation of human eosinophils, macrophages, and neutrophils by the phagocytic stimulus serum-opsonized zymosan (SOZ). CI-959 inhibited the respiratory burst of eosinophils and neutrophils, measured as the generation of superoxide anion, with IC50s of 9.6 and 14.5 microM, respectively. In contrast, 100 microM CI-959 inhibited superoxide anion generation by human macrophages by only 22.7%. The compound exhibited a different inhibition profile for lysosomal enzyme release from these cells. At 100 microM, CI-959 inhibited the release of eosinophil peroxidase and macrophage N-acetyl-beta-D-glucosaminidase by only 19.5 and 25.6%, respectively. In contrast, CI-959 inhibited the release of the neutrophil primary granule enzyme myeloperoxidase with an IC50 of 7.5 microM, while inhibiting release of lysozyme from secondary granules by only 11.4% at 100 microM. These results demonstrate that oxygen radical generation and lysosomal enzyme release by human leukocyte populations are differentially regulated by CI-959.

[Antibiotic sensitivity of forty-four strains of group EF4 bacteria: study of minimum inhibitory concentrations using the agar dilution method]

EF4 bacteria are found in animal saliva and may contaminate bite wounds. Minimum inhibitory concentrations of 36 antimicrobials against 44 EF4 strains were determined using dilution in Mueller-Hinton agar. EF4 bacteria were susceptible to aminopenicillins, carboxypenicillins, ureidopenicillins, third-generation cephalosporins, fluoroquinolones, rifampicin, and trimethoprime-sulfamethoxazole. Susceptibility was intermediate for penicillin G, low for macrolides and variable for aminoglycosides. EF4 bacteria were resistant to lincomycin and trimethoprime. Routine prophylactic treatment of bite-induced Pasteurella infections using an aminopenicillin or a cycline also protects against EF4 infection of the wound.

Inhibition of interleukin-2 production and lymphocyte responsiveness by the cell activation inhibitor, CI-959

CI-959 (5-methoxy-3-(1-methylethoxy)-N-1H-tetrazol-5-yl-benzo [b]-thiophene-2-carboxamide), an antiallergy compound, blocked release of IL-2 from Con A stimulated rat splenocytes and human lymphocytes with respective IC50s of 19.1 and 23.1 microM. Inhibition of IL-2 production required the presence of CI-959 in culture medium for the first 9 hr. CI-959 also inhibited Con A-stimulated rat and human lymphocyte proliferation with IC50s of 4.7 and 5.4 microM, respectively. Inhibition of the Con A proliferative response could not be overcome by exogenous recombinant human IL-2 (300 units/ml) in either the rat or human systems. Although potent in the human mixed lymphocyte reaction (IC50 = 3.5 microM), CI-959 was less effective in blocking the PHA response (IC50 = 43.9 microM), and had minimal effect on the release of IL-1 and TNF alpha from LPS-stimulated human monocytes. These findings suggest that CI-959 selectively inhibits some lymphocyte functions, as opposed to monocyte functions, and that among these is the production of IL-2.

Selective in vitro inhibition of human MOLT-4 T lymphoblasts by the novel purine nucleoside phosphorylase inhibitor, CI-972

CI-972 (2,6-diamino-3,5-dihydro-7-(3-thienylmethyl)-4H-pyrrolo[3,2- d]pyrimidin-4-one monohydrochloride, monohydrate) is a competitive inhibitor of PNPase (E.C. 2.4.2.1., Ki = 0.83 microM) entering clinical trials as a T cell-selective immunosuppressive agent. Neither CI-972 (less than or equal to 50 microM) nor dGuo (less than or equal to 10 microM) inhibited [3H]Thd uptake by human MOLT-4 (T cell) or MGL-8 (B cell) lymphoblasts, but in the presence of 10 microM dGuo, the IC50 for CI-972 decreased to 3.0 microM for MOLT-4 but remained at greater than 50 microM for MGL-8. Inhibition of MOLT-4 growth was associated with an increase in dGTP that was dependent on CI-972 concentration and inhibited by 2'-deoxycytidine. Growth could not be restored by hypoxanthine or adenine. No alterations in GTP pools were noted in MOLT-4, and neither GTP nor dGTP were altered in MGL-8.

Novel thiophene-, pyrrole-, furan-, and benzenecarboxamidotetrazoles as potential antiallergy agents

The synthesis and antiallergic activity of a series of novel thiophene-, pyrrole-, furan-, and benzenecarboxamidotetrazoles are described. A number of compounds inhibit the release of histamine from anti-IgE-stimulated human basophils. Optimal inhibition is exhibited in compounds with a 3-alkoxy, a 4-halo, and a 5-methyl, 5-methoxy, or 5-bromo on a thiophene-2-carboxamidotetrazole.

Biochemical and pharmacological properties of CI-972, a novel 9-deazaguanine analog purine nucleoside phosphorylase (PNP) inhibitor

CI-972 (2,6-diamino-3,5-dihydro-7-(3-thienylmethyl)-4H-pyrrolo[3, 2-d]pyrimidin-4-one monohydrochloride, monohydrate) is a novel inhibitor of PNP (Ki = 0.83 microM) under development as a T cell-selective immunosuppressive agent. CI-972 inhibited proliferation (3H-thymidine uptake) of human MOLT-4 (T cell) but not MGL-8 (B cell) lymphoblasts with respective IC50s of 3.0 and greater than 50 microM when tested with 10 microM 2'-deoxyguanosine. Without addition of exogenous 2'-deoxyguanosine, CI-972 was not inhibitory to any human T or B lymphoblastoid cell line tested. 2'-Deoxycytidine (10 microM), but not hypoxanthine or adenine, restored MOLT-4 cell growth. Inhibition of 3H-thymidine uptake in MOLT-4 cells correlated with accumulation of dGTP, while alterations in guanine nucleotides were not observed. 2'-Deoxycytidine (10 microM) also blocked dGTP accumulation in MOLT-4 cells. CI-972 showed activity in vivo over a broad dose range: At 5-150 mg/kg p.o., CI-972 produced dose-dependent elevation of plasma inosine one hr after administration to rats (mean maximum of 2.62 vs. 0.06 microM in controls). Guanosine was also significantly elevated in a concentration-dependent manner, although the effect was not as impressive. Plasma nucleosides remained statistically-significantly elevated for up to four hr following a single oral dose of CI-972.

Inhibition of human neutrophil activation by the allergic mediator release inhibitor, CI-949

The allergic mediator release inhibitor Cl-949 [5-methoxy-3-(1-methylethoxy)-1-phenyl-N-1H-tetrazol-5-yl-1H -indole-2-carboxamide, L-arginine salt] was evaluated for its effects on human neutrophil functions. Cl-949 (100 microM) inhibited spontaneous migration and chemotaxis toward f-met-leu-phe (FMLP) by 49.1% and 45.8%, respectively. At the same concentration, Cl-949 inhibited the phagocytosis of serum-opsonized zymosan (SOZ) by 39.0%. Cl-949 inhibited leukotriene B4 and thromboxane B2 release in response to SOZ with IC50s of 2.0 microM and 3.3 microM, while inhibiting the response to FMLP with IC50s of 1.7 and 2.0 microM. Cl-949 also inhibited myeloperoxidase release from primary lysosomal granules in response to the following stimuli with the respective IC50s (microM): C5a (40.3); FMLP (34.4): SOZ (21.4); concanavalin A (Con A) 3.9); and calcium ionophore A23187 (91.2). In contrast, Cl-949 inhibited lysozyme release from secondary granules in response to SOZ and Con A with IC50s of 99.3 and 56.1 microM, while inhibiting the response to C5a, FMLP, and A23187 by 41.2%, 52.4%, and 10.0%, respectively, at 100 microM. Cl-949 (100 microM) had no inhibitory effect against lysozyme release in response to L-alpha-1,2 dioctanoylglycerol (DiC8), or phorbol 12-myristate 13-acetate (PMA). Cl-949 inhibited superoxide anion generation stimulated by FMLP and Con A with IC50s of 33.9 and 25.8 microM, while inhibiting the response to C5a, SOZ, and A23187 by 36.6%, 24.8%, and 14.1% and having no effect on the response to DiC8 or PMA at 100 microM. These results demonstrate preferential inhibition of arachidonic acid metabolism and degranulation of primary lysosomal granules by Cl-949 with selectivity for stimuli which promote intracellular calcium mobilization or calcium influx.

Inhibition of histamine, leukotriene C4/D4, and thromboxane B2 release from human leukocytes and human chopped lung mast cells by the allergic mediator release inhibitor, CI-949

The novel antiallergy compound, 5-methoxy-3-(1-methylethoxy)-1-phenyl-N-1H-tetrazol-5-yl-1H- indole-2- carboxamide, L-arginine salt (CI-949), inhibited mediator release from human basophilic leukocytes and from human chopped lung mast cells challenged with anti-IgE. In leukocytes, CI-949 was a more potent inhibitor of leukotriene C4/D4 and thromboxane B2 release (concentration of drug that inhibits mediator release by 50% [IC50] 0.5 and 0.1 mumol/L, respectively) than of histamine (IC50, 11.4 mumol/L) when anti-IgE was the challenging stimulus. In human lung, inhibition of release of all three mediators occurred at approximately equal concentrations (IC50s for histamine, 16.6 mumol/L; for leukotriene C4/D4, 7.1 mumol/L; and for thromboxane B2, 6.2 mumol/L). The inhibition of histamine release from basophils by CI-949 was further characterized using a variety of stimuli. Challenge with anti-IgE, histamine-releasing factor derived from lymphocytes, N-formyl-L-methionyl-L-leucyl-L-phenylalanine, and concanavalin A revealed potent inhibition (IC50, 10 to 15 mumol/L). CI-949 was less potent versus calcium ionophore A23187, phorbol myristate acetate (12-o-tetradecanoylphorbol-13-acetate), and C5a (IC50s, 30, 54, and 60 mumol/L, respectively). These results suggest that diverse pathways of cell activation-excitation coupling exist for different stimuli in basophils. Furthermore, the activity and potency of CI-949 in inhibiting release of histamine, leukotrienes, and thromboxane from both human basophils and mast cells suggest that the compound will be effective clinically for indications in which these mediators are implicated, including asthma and allergic rhinitis.

Differential regulation of the activation of human eosinophils, macrophages, and neutrophils: effect of the allergic mediator release inhibitor CI-949

The allergic mediator release inhibitor CI-949 [5-methoxy-3-(1- methylethoxy)-1-phenyl-N-1H-tetrazol-5-yl-1H-indole-2-carbox amide L-arginine salt] was evaluated for its effect on the activation of human eosinophils, macrophages, and neutrophils by the phagocytic stimulus serum-opsonized zymosan (SOZ). CI-949 inhibited the SOZ- stimulated respiratory burst of eosinophils, measured as the generation of superoxide anion, with an IC50 of 22.8 microM. At concentrations of 100 microM, CI-949 had no inhibitory effect against lysosomal enzyme release by these cells. At 100 microM, CI-949 had no inhibitory effect against release of eosinophil peroxidase while inhibiting release of the macrophage lysosomal enzyme N-acetyl-beta-D- glucosaminidase by only 11.7 percent. In contrast, CI-949 inhibited the release of the neutrophil primary granule enzyme myeloperoxidase inhibiting of 21.4 microM, while inhibiting release of lysozyme from lysosomal enzyme release from secondary granules with an IC50 of 99.3 microM. These results demonstrate that oxygen radical generation and lysosomal enzyme release by human eosinophils, macrophages and neutrophils are differentially regulated by CI-949. These results suggest that these inflammatory cells may have distinct stimulus-related coupling mechanisms.

Inhibition of human neutrophil activation by the allergic mediator release inhibitor, CI-949: mechanism of inhibitory activity

CI-949 [5-methyl-3-(1-methylethoxy)-1-phenyl-N-1H-tetrazol-5-yl-1H- indole-2- carboxamide, L-arginine salt] inhibits human neutrophil activation in response to stimuli which promote calcium mobilization or calcium influx. This report further examines the effect of CI-949 on phosphoinositide-dependent stimulus-response coupling. At 100 microM, CI-949 had no inhibitory effect on human neutrophil phospholipase C or protein kinase C. In contrast, CI-949 inhibited FMLP-stimulated intracellular calcium mobilization with an IC50 of 8.4 microM. The compound was also a potent calmodulin antagonist, inhibiting calmodulin-dependent phosphodiesterase activity with an IC50 of 31.0 microM. The calmodulin antagonist activity of CI-949 was confirmed by fluorescence spectroscopy. These results demonstrate that CI-949 may function through inhibition of calcium- and calmodulin-dependent signal transduction processes.

CI-949: a new, potential antiallergy compound inhibits antigen-induced allergic reactions in guinea-pigs in vitro and in vivo

CI-949 (5-methoxy-3-(1-methyl-ethoxy)-1-phenyl-N-1H-tetrazol-5-yl-1H -indole-2-carboxamide) effectively inhibited the release of histamine and the synthesis or release of immunoreactive sulfidopeptide leukotrienes C4-D4 and thromboxane B2 from antigen-challenged lung fragments of of actively sensitized guinea-pigs. The IC50s were 26.7 +/- 2.8 microM for histamine, 2.7 +/- 2.4 microM for leukotriene, and 3.0 +/- 1.8 microM for thromboxane. Drugs including ketotifen, cromolyn and nedocromil did not inhibit histamine release or did so only at high concentrations, and only cromolyn inhibited the synthesis or releases of the 2 eicosanoids. A dose of 50 mg/kg i.p. of CI-949 protected conscious, aerosol-allergen challenged guinea-pigs for at least 1 h and 100 mg/kg i.p. or per os protected for at least 2 h. These results, the comparisons to standard antiallergic drugs, and other data from experiments with human lung fragments and isolated peripheral leukocytes 1,2,3,4 suggest that CI-949 should be evaluated for clinical activity against allergic and inflammatory conditions in which histamine, sulfidopeptide leukotrienes, and/or thromboxane mediate symptoms.

CI-959, a new, potential antiallergic drug, inhibits mediator release from lung and contractions of human airways in vitro

Many symptoms of the immediate allergic response can be attributed to the synthesis/release and subsequent actions of histamine and metabolic products of arachidonic acid oxidation. CI-959 [5-methoxy-3-(1-methylethoxy)-N-1H-tetrazole-5-yl-benzo(b) thiophene-2-carboxamide], a new, potential antiallergic drug, inhibited the release of histamine, immunoreactive sulfidopeptide leukotrienes C4, D4 and E4 and immunoreactive thromboxane B2 from immunologically activated guinea-pig and human lung cells in vitro. The IC50s of CI-959 using guinea-pig lung were: histamine, 0.8 +/- 1.4 microM; leukotriene, 0.7 +/- 1.6 microM and thromboxane, 9.6 +/- 3.3 microM. Using human lung the IC50s were: 2.3 +/- 1.3 microM for histamine; 0.3 +/- 5.1 microM for leukotriene, and 0.3 +/- 2.6 microM for thromboxane. CI-959 caused a concentration-dependent inhibition of anti-IgE-induced contractions of human bronchial muscle. Mean percent inhibitions were 45, 65 and 96 at 1, 3 and 10 microM, respectively. Cromolyn, 10 microM, inhibited bronchial contractions only 42%. The ability of CI-959 to inhibit these immunologically induced contractions indicates that the release of all mediators responsible for bronchoconstriction was effectively inhibited. These data suggest that CI-959 may be effective in preventing the development of symptoms directly related to inflammatory mediator release in a variety of allergic and inflammatory states.

Novel indolecarboxamidotetrazoles as potential antiallergy agents

The synthesis and antiallergic potential of a series of novel indolecarboxamidotetrazoles are described. A number of compounds inhibit the release of histamine from anti-IgE-stimulated basophilic leukocytes obtained from allergic donors. Optimal inhibition is exhibited by compounds with 3-alkoxy, 5-methoxy, and 1-phenyl substituents on the indole core structure. Compound 8d (5-methoxy-3-(1-methylethoxy)-1-phenyl-N-1H-tetrazol-5-yl-1H -indole-2-carboxamide; designated CI-949) is a potent inhibitor of histamine release from human basophils and from guinea pig and human chopped lung.

In vitro effects of the antiallergy compound, CI-949, on interleukin-1 and 2 release, and on mitogen and alloantigen responsiveness

CI-949 (5-methoxy-3-(1-methylethoxy)-1-phenyl-N-1H-tetrazol-5-yl-1H -indole- 2-carboxamide, L-arginine salt), an antiallergy compound, was found to be a weak inhibitor of IL-1 release from LPS-stimulated murine peritoneal exudate cells and human peripheral blood leukocytes, with IC50S of 186.2 and 267.9 microM, respectively. CI-949 was also a poor inhibitor of release of IL-2 from Con A-stimulated rat splenocytes (37% inhibition at 100 microM). CI-949 did produce concentration-related inhibition of the response of human lymphocytes to PHA and Con A (IC50S = 44.7 and 21.5 microM, respectively) as well as in the mixed lymphocyte reaction (MLR) (IC50 = 16.8 microM). The clinical significance of these latter findings is unknown at present.

Inhibition of human neutrophil activation by the allergic mediator release inhibitor, CI-922: mechanism of inhibitory activity

3,7-Dimethoxy-4-phenyl-N-1H tetrazol-5-yl-4H-furo[3,2-b]-indole-2- carboxamide, L-arginate (CI-922) is a potent inhibitory of human neutrophil functions in response to a variety of stimuli. In this report, the effects of CI-922 on specific processes involved in stimulus-response coupling are evaluated. CI-922 does not inhibit human neutrophil phospholipase C or protein kinase C activities. CI-922 is shown to inhibit calmodulin-dependent enzyme activation. The calmodulin antagonist activity is confirmed by calmodulin-Sepharose affinity chromatography. These results suggest that CI-922 inhibits neutrophil activation by preventing the activation of calmodulin-dependent enzymes, implying a critical role for such enzymes in stimulus-response coupling.

Inhibition of human neutrophil activation by the allergic mediator release inhibitor, CI-922: differential inhibition of responses to a variety of stimuli

The allergic mediator release inhibitor 3,7-dimethoxy-4-phenyl-N-1H-tetrazol-5-yl-4H-furo[3,2-b]indole-2- carboxamide, L-arginate (CI-922) is a potent inhibitor of human neutrophil functions in vitro. Over a concentration range from 1 to 100 mumol CI-922 inhibits the chemotactic response of neutrophils to the synthetic chemotaxin N-formyl-methionyl-leucyl-phenylalanine (FMLP). CI-922 also inhibits respiratory and secretory responses of neutrophils in response to agents that stimulate phospholipase C-dependent phosphoinositide hydrolysis to generate the second messengers inositol 1,4,5, trisphosphate and 1,2 diacylglycerol, including: the plasma membrane receptor-specific ligands FMLP and C5a; serum-opsonized zymosan; concanavalin A; and the guanine nucleotide regulatory protein-specific stimulus guanosine-5'-0-(3-thiotriphosphate) (GTP gamma S). CI-922 also inhibits neutrophil functions stimulated by the calcium ionophore A23187. In contrast, CI-922 does not inhibit neutrophil responses to protein kinase C-specific stimuli such as phorbol 12-myristate 13-acetate (PMA) or L-alpha-1,2 dioctanoylglycerol (DiC8). CI-922 also fails to inhibit the synergistic activation of the respiratory burst by suboptimal concentrations of PMA and calcium ionophore A23187. The observation that CI-922 inhibits neutrophil responses to a variety of soluble and particulate stimuli, excluding protein kinase C-specific stimuli, allows us to postulate the site of action of the compound. We propose that CI-922 inhibits neutrophil activation at a site distal to signal transduction through the guanine nucleotide regulatory protein required for second messenger generation but proximal to phosphorylation reactions mediated by protein kinase C and calmodulin-dependent protein kinases.

Specific inhibition of phorbol ester and DiC8-induced histamine release from human basophils by the protein kinase C inhibitors, H-7 and H-9

The release of histamine and other inflammatory mediators from human basophils is triggered by numerous stimuli, including chemical, physical and receptor-mediated activators. Several mechanisms of cell activation including protein kinase C activation have been proposed to operate in these cells. We used phorbol ester and DiC8 to induce histamine release from human basophils and the protein kinase C inhibitors H-7 and H-9 to inhibit this release. Both DiC8 and TPA induced histamine release were inhibited by H-7 (ID 50 = 37 mcM) and H-9 (IC 50 = 20 mcM). However, anti-IgE, fmlp and A23187-induced histamine release were unaffected. In contrast, the calmodulin antagonists W-7 and perphenazine effectively inhibited histamine release by all five stimuli. Therefore, different biochemical pathways appear to be critical for basophil activation depending on the nature of the stimulus used.

[Antibiotic sensitivity of Pasteurella multocida and related bacteria (bacterial groups M5 and EF4). Studies of minimal inhibitory concentrations by agar dilution]

We have been isolating Pasteurella multocida and similar germs increasingly during the last few years: due to the rabies coming back in Eastern France, more consultations have been held following animal bites; samples are then taken for a bacteriologic research. We have studied their sensitivity towards 30 antibiotics. The determination of the MIC was achieved through the agar dilution method on 34 Pasteurella multocida of human origin issued after bites and expectorations, 4 EF4 and 4 M5. The Pasteurella are very sensitive to: beta-lactam antibiotics (the lowest MIC were observed for ureido-penicillins, amino-benzylpenicillins and third generation cephalosporins), chloramphenicol, cyclines and quinolones. Fosfomycin colistin and aminoglycosides are also active but with higher MIC. The macrolides have got a slow or no activity at all. The M5 are susceptible to the same antibiotics as Pasteurella but with slightly higher concentrations. Regarding EF4, minor sensitivity or resistance to penicillin G, cephalothin and cefamandole can be pointed out.

Release of histamine from human leukocytes by one preparation of IgG oligomers

In preliminary experiments aimed at investigating the effect of covalently cross-linked human myeloma subclass proteins on histamine release from human leukocytes, we observed one preparation (designated here IgG-HR) made from pooled, purified immunoglobulin G, which consistently released histamine from these cells. Dimers and trimers, but not monomers isolated from columns of Sephadex G-200 and Ultrogel AcA22 following incubation of immunoglobulin G (Nordic Laboratories) with dimethyl suberimidate, released histamine from cells of all donors tested. In contrast, cells from the same donors showed variable responsiveness to dimers of IgE (prepared by similar techniques) or to anti-IgE. IgG-HR failed to release histamine from a "basophil-rich" mononuclear cell preparation depleted of most of the erythrocytes, platelets, neutrophils and eosinophils by centrifugation through a Ficoll-Hypaque cushion. The data suggest that IgG-HR was releasing histamine indirectly from basophils by first interacting with another cell. IgG oligomers prepared from different sources of pooled, purified IgG failed to release histamine. Although we did not have sufficient IgG-HR to adequately define this releasing activity, we feel that the data represent a potentially novel, if rare, mechanism of mediator release involving basophils and another cell.