Cyanobacteria Scytonema javanicum and Scytonema ocellatum Lipopolysaccharides Elicit Release of Superoxide Anion, Matrix-Metalloproteinase-9, Cytokines and Chemokines by Rat Microglia In Vitro.

Cosmopolitan Gram-negative cyanobacteria may affect human and animal health by contaminating terrestrial, marine and freshwater environments with toxins, such as lipopolysaccharide (LPS). The cyanobacterial genus <italic>Scytonema</italic> (<italic>S</italic>) produces several toxins, but to our knowledge the bioactivity of genus <italic>Scytonema</italic> LPS has not been investigated. We recently reported that cyanobacterium <italic>Oscillatoria</italic> sp. LPS elicited classical and alternative activation of rat microglia in vitro. Thus, we hypothesized that treatment of brain microglia in vitro with either cyanobacteria <italic>S. javanicum</italic> or <italic>S. ocellatum</italic> LPS might stimulate classical and alternative activation with concomitant release of superoxide anion (O2−), matrix metalloproteinase-9 (MMP-9), cytokines and chemokines. Microglia were isolated from neonatal rats and treated in vitro with either <italic>S. javanicum</italic> LPS, <italic>S. ocellatum</italic> LPS, or <italic>E. coli</italic> LPS (positive control), in a concentration-dependent manner, for 18 h at 35.9 °C. We observed that treatment of microglia with either <italic>E. coli</italic> LPS, <italic>S. javanicum</italic> or <italic>S. ocellatum</italic> LPS generated statistically significant and concentration-dependent O2−, MMP-9 and pro-inflammatory cytokines IL-6 and TNF-α, pro-inflammatory chemokines MIP-2/CXCL-2, CINC-1/CXCL-1 and MIP-1α/CCL3, and the anti-inflammatory cytokine IL-10. Thus, our results provide experimental support for our working hypothesis because both <italic>S. javanicum</italic> and <italic>S. ocellatum</italic> LPS elicited classical and alternative activation of microglia and concomitant release of O2−, MMP-9, cytokines and chemokines in a concentration-dependent manner in vitro. To our knowledge this is the first report on the toxicity of cyanobacteria <italic>S. javanicum</italic> and <italic>S. ocellatum</italic> LPS to microglia, an immune cell type involved in neuroinflammation and neurotoxicity in the central nervous system. [ABSTRACT FROM AUTHOR]