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

Abstract

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 Scytonema (S) produces several toxins, but to our knowledge the bioactivity of genus Scytonema LPS has not been investigated. We recently reported that cyanobacterium Oscillatoria 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 S. javanicum or S. ocellatum 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 S. javanicum LPS, S. ocellatum LPS, or E. coli LPS (positive control), in a concentration-dependent manner, for 18 h at 35.9 °C. We observed that treatment of microglia with either E. coli LPS, S. javanicum or S. ocellatum 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 S. javanicum and S. ocellatum 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 S. javanicum and S. ocellatum LPS to microglia, an immune cell type involved in neuroinflammation and neurotoxicity in the central nervous system.

Effects of cyanobacterial toxins on the human gastrointestinal tract and the mucosal innate immune system

“…In vitro studies show for example that LPS from M. aeruginosa blooms and strains activates blood cells, namely human polymorphonuclear leukocytes and monocytes, which are involved in the innate immune defense [157,158]. Furthermore, rat microglia were shown to be activated by LPS from different cyanobacterial species [173][174][175]. Taken together, these studies indicate that not only intestinal but also immune cells can be affected by cyanobacterial LPS.…”

6-Deoxy- and 11-Hydroxytolypodiols: Meroterpenoids from the Cyanobacterium HT-58-2

“…At the time of its original isolation, tolypodiol ( 3 ) was shown to reduce chemically induced inflammation in an in vivo mouse ear edema assay (ED 50 30 μg/ear for 3 vs 20 μg/ear for the positive control). As the yields of 1 and 2 precluded testing in the original assay system, 1 – 3 were assessed for their effects on in vitro activation and generation of proinflammatory mediators by rat neonatal microglia (Figure ) using the standard inflammation models in our laboratories. , Only 2 significantly inhibited the generation of proinflammatory thromboxane B2 (TXB 2 ) (apparent IC 50 = 0.1 μM). Lack of inhibition of superoxide anion (O 2 – ) generation suggests that 2 inhibits TXB 2 generation in rat microglia through a mechanism that may be cyclooxygenase dependent.…”

Toxic or Otherwise Harmful Algae and the Built Environment

“…Lipopolysaccharides (LPS) from Cyanoprokaryota are discussed as potentially (irritant) poisonous compounds [ 129 , 130 ]. In Table 1 , important toxins produced in the listed taxa with emphasis on airborne or aerophytic forms are given, as available from literature, also partly considering further toxic compounds or compounds under suspicion to be toxic not discussed above.…”

“…In order to give an overview on the abundance of potentially harmful algae in the built environment (indoor, Lampenflora, building surfaces), I enlisted airborne algae, potentially toxic and/or allergenic, from literature and set them into context with the built environment ( Table 1 ). This extract is based on a choice of literature, mainly on comprehensive studies or work otherwise important in the theme [ 3 , 5 , 8 , 10 , 17 , 19 , 23 , 26 , 74 , 107 , 116 , 129 , 130 , 140 , 141 , 142 , 143 , 144 , 145 , 146 , 147 , 148 , 149 , 150 , 151 , 152 , 154 , 155 , 156 , 157 , 158 , 159 , 160 , 161 , 162 , 163 , 164 , 165 , 166 , 167 , 168 , 169 , 170 , 171 , 270 ]. Airborne algae were sampled with different methods, e.g., fan dust sampling, filtration, impaction, impingement, Rotorod sampler, sedimentation, application of a vacuum cleaner and wind nets.…”

“…Algae names were checked with [ 30 , 144 , 145 , 146 , 307 ]. Additionally, information is given on potential health effects including major toxins produced from toxigenic species [ 17 , 26 , 74 , 107 , 116 , 129 , 130 , 143 , 144 , 145 , 146 , 147 , 148 , 149 , 150 , 151 , 152 ]. Seventy-nine taxa of potentially harmful airborne algae are listed.…”