Novel conjugate of moxifloxacin and carboxymethylated glucan with enhanced activity against Mycobacterium tuberculosis.

Mycobacterium tuberculosis is an intracellular pathogen that persists within macrophages of the human host. One approach to improving the treatment of tuberculosis (TB) is the targeted delivery of antibiotics to macrophages using ligands to macrophage receptors. The moxifloxacin-conjugated dansylated carboxymethylglucan (M-DCMG) conjugate was prepared by chemically linking dansylcadaverine (D) and moxifloxacin (M) to carboxymethylglucan (CMG), a known ligand of macrophage scavenger receptors. The targeted delivery to macrophages and the antituberculosis activity of the conjugate M-DCMG were studied in vitro and in vivo. Using fluorescence microscopy, fluorimetry, and the J774 macrophage cell line, M-DCMG was shown to accumulate in macrophages through scavenger receptors in a dose-dependent (1 to 50 microg/ml) manner. After intravenous administration of M-DCMG into C57BL/6 mice, the fluorescent conjugate was concentrated in the macrophages of the lungs and spleen. Analyses of the pharmacokinetics of the conjugate demonstrated that M-DCMG was more rapidly accumulated and more persistent in tissues than free moxifloxacin. Importantly, therapeutic studies of mycobacterial growth in C57BL/6 mice showed that the M-DCMG conjugate was significantly more potent than free moxifloxacin.

Soluble glucan protects against endotoxin shock in the rat: the role of the scavenger receptor.

Soluble carboxymethyl-b-1,3-glucan (CMG), a possible ligand for scavenger receptors, has macrophage-activating action but lacks the granulomatose inflammatory side effect: it is a promising immunomodulator that may mitigate the severity of sepsis. This motivated us to study in rats the effect of CMG (25 mg/kg), injected into the tail vein at 48 and 24 h prior to the administration of 5 mg/kg Escherichia coli 0127.B8 endotoxin on survival, hemodynamic condition, and, in vitro, on the chemiluminescence of PMNs and macrophages, and on macrophagal tumor necrosis factor (TNF) production. Acetylated low density lipoprotein (AcLDL) clearance in vivo and in vitro binding to macrophages was used to study scavenger receptor function. In the nonpretreated group 9 of 10 rats died during the first 24 h after endotoxin, but all CMG-pretreated rats survived. CMG-pretreatment prevented severe decreases in cardiac output and blood pressure after endotoxin. Chemiluminescence of macrophages and PMNs from CMG-pretreated rats was about two times less (p < .05) than that from nonpretreated ones; the endotoxin induced TNF production by macrophages also decreased. Pretreatment with CMG increased, but coinjection of CMG and AcLDL decreased the AcLDL clearance, while coinjection of endotoxin and AcLDL decreased the survival rate. In vitro AcLDL uptake by macrophages decreased after coinjection with CMG. Our results thus showed that CMG was protective in rat endotoxin shock, which seemed partly connected with enhancement of endotoxin clearance through scavenger receptors and to decreased TNF production.

Effect of verapamil and nifedipine on cholesteryl ester metabolism and low-density lipoprotein oxidation in macrophages.

Using mouse macrophage cultures, the effects of verapamil and nifedipine on cholesteryl ester and low-density lipoprotein (LDL) metabolism were studied with special reference to the following parameters: (a) incorporation of [14C]oleate into cholesteryl esters (ChE), (b) contents of total and free cholesterol (FCh), (c) liberation of [14C]oleate from ChE and incorporation of [3H]FCh into ChE, (d) excretion of [3H]Ch from the cells, and (e) LDL oxidation. Verapamil and nifedipine (10-100 microM) were shown to decrease in a dose-dependent manner the incorporation of [14C]oleate into ChE and to increase the concentration of FCh but had no appreciable effect on the concentration of total cholesterol in macrophages cultured in the presence of acetylated LDL. The drugs stimulated the liberation of [14C]oleate from cellular ChE. The pharmacological concentrations (25-75 microM) of verapamil and nifedipine increased the excretion of [3H]FCh from ChE of macrophages in the presence of serum and high-density lipoproteins. The same concentrations of the drugs inhibited both LDL-derived malonyldialdehyde-like products and nitroblue tetrazolium dye reduction in a dose-dependent fashion. The results obtained suggest that verapamil and nifedipine exert their macrophage-mediated antiatherosclerotic effect via reduction of LDL oxidative modification, reduction of intracellular ChE synthesis, stimulation of ChE hydrolysis and cholesterol excretion from the cells.

Mononuclear phagocyte system responsiveness in CCl4-induced liver cirrhosis.

In rats with CCl4-induced liver cirrhosis, a twofold decrease of blood clearance rate and a fourfold reduction in number of Kupffer cells taking up colloidal carbon particles has been demonstrated. Zymosan stimulation does not lead to granuloma-like structures in the liver of CCl4-cirrhotic rats. In cirrhotic rats, unlike controls, the cathepsin D activity of liver tissue is very little increased by zymosan treatment and there is virtually no increase in collagenolytic activity. The increase in PGE content in cirrhotic rat liver after prodigiosan stimulation was 2.5 times less than in stimulated control animals. In cirrhotic rats, the IL-1 producing capacity of blood monocytes in vitro in response to lipopolysaccharide drops almost fivefold. The total count of bone marrow-derived myeloid colonies in cirrhotic zymosan-stimulated animals was reduced by 1.5-fold whereas in control animals zymosan induced a 1.8-fold increase in the number of myeloid colonies. The number, uptake and nitroblue tetrazolium-reducing capacities of lung, spleen, peritoneal and bone marrow macrophages in animals with liver cirrhosis were only slightly increased in response to zymosan as compared to control animals. The low response of extrahepatic macrophages to stimuli in cirrhotic animals is thought to be due to their premobilization during the development of cirrhosis.