Pectic polysaccharides isolated from Malian medicinal plants protect against Streptococcus pneumoniae in a mouse pneumococcal infection model.

The aim of this study was to investigate whether the pectic polysaccharides BP-II, Oc50A1.I.A and CC1P1 isolated from the Malian medicinal plants Biophytum petersianum, Opilia celtidifolia and Cola cordifolia, respectively, were able to protect against Streptococcus pneumoniae infection in mice. The pectin preparations were administered intraperitoneally 3 h before challenge with S. pneumoniae serotype 6B. Blood samples were obtained from all animals before and at 3 h, 24 h and 72 h after challenge with the pneumococci. The number of bacteria in blood was recorded and the blood concentration of a range of cytokines measured. The pretreatment with BP-II, Oc50A1.I.A and CC1P1 demonstrated a protective activity against S. pneumoniae serotype 6B infection, albeit at different range of concentrations. The pectins showed no direct antibacterial effects towards S. pneumonia; however, they induced the production of a range of cytokines and chemokines. We have previously shown that BP-II, Oc50A1.I.A and CC1P1 exhibit complement fixation activity and also that BP-II and Oc50A1.I.A stimulate macrophages to produce NO. The observed clinical effect might therefore be linked to the ability of the pectic polysaccharides to stimulate the innate immune system.

Similar superantigen gene profiles and superantigen activity in norwegian isolates of invasive and non-invasive group a streptococci.

Group A streptococcus (GAS) harbours several virulence factors, including M protein (coded by the emm gene) and superantigens (SAgs). SAgs are extracellular toxins that directly activate the immune system by cross-binding to the HLA class II molecule and T cell receptor (TCR), thereby causing activation of up to 30% of the T cells and subsequent massive secretion of cytokines. Forty-eight GAS strains isolated from patients at Norwegian hospitals between 1988 and 2004 were included in this study. Of these, 24 were invasive streptococcal toxic shock syndrome (STSS) or necrotizing fasciitis (NF) isolates and 24 were non-invasive pharyngitis isolates, matched for having the same T-type and year of isolation as the invasive isolates. The isolates were characterized by emm sequence typing, multilocus sequence typing (MLST) and SAg gene profiles. A correlation between T-type, emm type, sequence type and SAg gene profile was revealed. No difference between invasive and non-invasive isolates regarding serotype or genotype was demonstrated. Selected invasive and non-invasive isolates with identical SAg gene profiles were analysed for SAg activity in bacterial growth culture media with and without human cell culture media added. A human T cell proliferation assay was used as measurement for SAg activity and simultaneously we also measured the cytokine content in normal human peripheral blood leucocyte cell culture media. The results revealed that invasive and non-invasive isolates did not differ significantly in SAg activity as it is present in semipurified bacterial culture medium.