engleski

Adjuvant activity of peptidoglycan monomer and its metabolic products

Peptidoglycan monomer, GlcNAc-MurNAc-L-Ala-D-isoGln-mesoDAP(wNH2)-D-Ala-D-Ala (PGM, PLIVA, Croatia) is a natural compound originating from bacterial peptidoglycan. It possesses many beneficial characteristics that are required for a pharmaceutical product. It is non-toxic, apyrogenic and water-soluble compound that can be consistently produced by a simple biotechnology procedure. It has a completely defined chemical structure. It can be lyophilised without a loss of biological activity and is stable over a great time period (over ten years in a lyophilised form). It is not immunogenic by itself. Because of bacterial origin it is very familiar to mammalian organism. Recently we have shown using ovalbumin (OVA) as an antigen that PGM possesses adjuvant properties in mice model1 stimulating specific IgGs and IgAs in the sera and not affecting either total or specific IgEs. Subtype analysis of specific IgGs revealed that PGM stimulated both IgG1 as well as IgG2a and IgG2b classes of antibodies. Analysis of IFN-g and IL-4 production from OVA specific cells isolated from draining lymph nodes of immunised mice, revealed stimulative action of PGM on production of both cytokines, indicating that PGM is stimulator of both Th1 and Th2 types of immune response. Here we report on two aspects of PGM's action: its influence on induction of long lasting specific memory and the testing of possible adjuvant action of its metabolic products. It is known that PGM is the substrate for the amidase present in mammalian blood that cleaves it into metabolic products, the pentapeptide and the dissacharide2. For monitoring PGM's action on induction of long lasting specific memory mice were immunised twice in two week interval either solely with OVA or with OVA plus PGM. Six months later mice were immunised with antigen alone and the group that received PGM had higher level of OVA specific antibodies as measured by ELISA. Metabolic products of PGM, the pentapeptide and the disaccharide, were enzymatically prepared in vitro, separated and purified by gel filtration methods and their purity checked by high pressure liquid chromatography and thin layer chromatography. They were apyrogenic (250mg/kg) as tested in pyrogenicity test in rabbits. Their possible adjuvant effect was tested in parallel with PGM in mice model using OVA as an antigen. They were both devoid of adjuvant activity of their parent compound in this model. In conclusion, results obtained indicate that PGM is a molecule capable of stimulating long lasting specific immunity, whose action could possibly be improved in formulations that would slow down its degradation. 1Tomašić et al. (2000) Vaccine 18: 1236 2 Valinger et al. (1982) Biochym. Biophys. Acta 710:63

peptidoglycan monomer; adjuvants; peptidoglycan metabolites

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