RESUMEN
We analyzed the mycolic acid composition of trehalose 6,6'-dimycolate (TDM) obtained from Mycobacterium, using thin layer chromatography, gas chromatography and gas chromatography-mass spectrometry. Utilizing TDM, whose structure was confirmed, granuloma formation in mice was investigated. All TDM used exhibited considerable granuloma formation activity in the lung and spleen. In particular, TDM from M. bovis showed the greatest activity and toxicity among mycobacterial TDM. We therefore discussed the relationship between the chemical structure and granuloma-forming activity of TDM, especially in relation to the structure of mycolic acid in TDM.
Asunto(s)
Factores Cordón/química , Mycobacterium/química , Ácidos Micólicos/química , Animales , Factores Cordón/metabolismo , Factores Cordón/toxicidad , Granuloma/inducido químicamente , Ratones , Mycobacterium/metabolismoRESUMEN
A newly isolated mycoloyl glycolipid (Rt. GM-2) from Rhodococcus terrae 70012 was identified and the granulomagenic and antitumor activities were studied as compared with trehalose-6,6'-dimycolate (cord factor) also from R. terrae (Rt. TDM). The alkaline hydrolysis products of Rt. GM-2 contained trehalose, methyl-alpha-mycolate and a less-polar ester than the usual methyl-alpha-mycolate, possibly beta-keto mycolate (1:1:1, by mol. ratios). On the other hand, analysis of alditol acetate obtained after the mild permethylation, NaBH4 reduction, and acetylation showed the occurrence of 2,3,4-tri-O-methyl-6-O-acetylglucitol. Therefore, the original glycolipid (Rt. GM-2) was identified tentatively as 6-O-alpha-mycoloyl 6'-O-beta-ketomycoloyl trehalose. Intravenous injection of Rt. GM-2 in the form of water-in-oil-in-water emulsion caused prominent granulomas in lungs and spleen of ICR and BALB/c mice. The granulomagenic effects were as strong as those caused by Rt. TDM. The lung and spleen weights reached peaks one week after an injection of Rt. GM-2 in mice and then gradually decreased. Multiple intravenous injections of Rt. GM-2 and Rt. TDM showed antitumor activity against subcutaneously implanted Sarcoma-180, and caused prominent granulomatous changes and growth suppression of mice.
Asunto(s)
Adyuvantes Inmunológicos , Antineoplásicos/uso terapéutico , Glucolípidos/uso terapéutico , Granuloma/inmunología , Ácidos Micólicos/uso terapéutico , Rhodococcus/metabolismo , Sarcoma/tratamiento farmacológico , Animales , Factores Cordón/uso terapéutico , Glucolípidos/aislamiento & purificación , Masculino , Ratones , Ratones Endogámicos BALB C , Ácidos Micólicos/aislamiento & purificación , Especificidad de Órganos , Células Tumorales CultivadasRESUMEN
Multiple intravenous injections (30 micrograms, ten times) in ICR mice of trehalose dimycolate and glucose monomycolate from Nocardia rubra, containing C36-48 mycolic acids, showed a prominent antitumor effect on a subcutaneously implanted sarcoma-180, an allogeneic sarcoma of mice with a significant granuloma formation in lungs, spleen and liver. On the other hand, mycoloyl glycolipids other than glucose monomycolate and trehalose dimycolate, such as mannose or fructose mycolate, showed no significant activity for tumor regression or granuloma formation in mice. Trehalose dimycolate and glucose monomycolate from N. rubra, and glucose monomycolate with C56-60 mycolic acids from Rhodococcus terrae also showed a distinctive priming activity for tumor necrosis factor (TNF), when lipopolysaccharide from Escherichia coli was administered as an eliciting agent. The TNF activity in the sera of mice was abrogated almost completely by anti-(murine TNF alpha) antibody with protein-A-agarose. Again in contrast, mannose and fructose mycolate from N. rubra and glucose monomycolate with C30-34 mycolic acids from Rhodococcus equi did not show such activities in mice. Meth-A, a syngeneic fibrosarcoma of BALB/c mice, was less sensitive to administration of glycolipids than sarcoma-180. These results indicated that the existence of a glucose or trehalose molecule was necessary for the expression of immunomodifying activities among various mycoloyl glycolipids differing in carbohydrate structure. However, since the administration of lipopolysaccharide was essentially required as an eliciting agent for the induction of TNF, while no eliciting agent was required for the antitumor activities, TNF does not seem to contribute directly to the antitumor activities of mycoloyl glycolipids in our systems. There was, however, a parallel structure-activity relationship among granuloma-forming, antitumor and TNF-priming activities, indicating that the structures of both the carbohydrate moiety and the mycoloyl residues influenced an initial step, such as macrophage activation, commonly and profoundly.
Asunto(s)
Antineoplásicos/farmacología , Glucolípidos/farmacología , Granuloma/inducido químicamente , Ácidos Micólicos/farmacología , Nocardia/análisis , Factor de Necrosis Tumoral alfa/biosíntesis , Animales , Peso Corporal/efectos de los fármacos , Femenino , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos ICR , Neoplasias Experimentales/tratamiento farmacológico , Relación Estructura-Actividad , Factor de Necrosis Tumoral alfa/inmunologíaRESUMEN
The immunomodifying activity of a novel mycoloyl glycolipid, trehalose 2,3,6'-trimycolate (GaGM), from a unique psychrophilic acid-fast bacterium, Rhodococcus aurantiacus, was examined. ICR mice were primed intravenously (i.v.) or intraperitoneally (i.p.) with liposomes containing GaGM (300 micrograms/mouse), and were administered LPS dissolved in saline (25 micrograms/mouse, i.v.) 2 weeks later. Two hours after injection of LPS, interferons (IFNs) and tumor necrosis factor (TNF) were induced significantly in mice sera. The increase in activities of IFNs and TNF was approximately paralleled with granuloma formation in spleen of mice primed with GaGM. However, IFNs and TNF were not induced either in mice primed with GaGM but not elicited with LPS, or in those primed with GaGM and elicited by GaGM. Both activities induced were lower in mice primed with trehalose mono- or dimycolate from R. aurantiacus (GaTMM, GaTDM) or TDM from Nocardia rubra than in GaGM-primed mice. Time course study showed that the maximum activity of each interferon (alpha, beta, or gamma) was observed at different stages after LPS administration; IFN-alpha, IFN-beta, and IFN-gamma appeared 3, 2, and 6 hours most abundantly after LPS administration, respectively.