• Home
  • Search Results
  • Lipopolysaccharide is a frequent and significant contaminant in microglia-activating factors.

Lipopolysaccharide is a frequent and significant contaminant in microglia-activating factors.

Glia (2007-10-03)
Jonathan R Weinstein, Sarah Swarts, Caroline Bishop, Uwe-Karsten Hanisch, Thomas Möller
ABSTRACT

Lipopolysaccharide (LPS/endotoxin) is a potent immunologic stimulant. Many commercial-grade reagents used in research are not screened for LPS contamination. LPS induces a wide spectrum of proinflammatory responses in microglia, the immune cells of the brain. Recent studies have demonstrated that a broad range of endogenous factors including plasma-derived proteins and bioactive phospholipids can also activate microglia. However, few of these studies have reported either the LPS levels found in the preparations used or the effect of LPS inhibitors such as polymyxin B (PMX) on factor-induced responses. Here, we used the Limulus amoebocyte lysate assay to screen a broad range of commercial- and pharmaceutical-grade proteins, peptides, lipids, and inhibitors commonly used in microglia research for contamination with LPS. We then characterized the ability of PMX to alter a representative set of factor-induced microglial activation parameters including surface antigen expression, metabolic activity/proliferation, and NO/cytokine/chemokine release in both the N9 microglial cell line and primary microglia. Significant levels of LPS contamination were detected in a number of commercial-grade plasma/serum- and nonplasma/serum-derived proteins, phospholipids, and synthetic peptide preparations, but not in pharmaceutical-grade recombinant proteins or pharmacological inhibitors. PMX had a significant inhibitory effect on the microglia-activating potential of a number of commercial-, but not pharmaceutical-grade, protein preparations. Novel PMX-resistant responses to alpha(2)-macroglobulin and albumin were incidentally observed. Our results indicate that LPS is a frequent and significant contaminant in commercial-grade preparations of previously reported microglia-activating factors. Careful attention to LPS levels and appropriate controls are necessary for future studies in the neuroinflammation field.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Oleoyl-L-α-lysophosphatidic acid sodium salt, ≥98%, solid
Sigma-Aldrich
Sphingosine 1-phosphate, ≥95%, powder
Sigma-Aldrich
Albumin from rat serum, lyophilized powder, essentially fatty acid free, essentially globulin free, ≥99% (agarose gel electrophoresis)
Sigma-Aldrich
Albumin from rat serum, lyophilized powder, ≥96% (agarose gel electrophoresis)
Sigma-Aldrich
α2-Macroglobulin from human plasma, BioUltra, ≥98% (SDS-PAGE)
Sigma-Aldrich
IgM from bovine serum, reagent grade, ≥95% (SDS-PAGE or HPLC), buffered aqueous solution
Sigma-Aldrich
Sera from rat, frozen liquid
Sigma-Aldrich
Albumin from rat serum, lyophilized powder, essentially globulin free, ≥99% (agarose gel electrophoresis)

Social Media

LinkedIn icon
Twitter icon
Facebook Icon
Instagram Icon

MilliporeSigma

Research. Development. Production.

We are a leading supplier to the global Life Science industry with solutions and services for research, biotechnology development and production, and pharmaceutical drug therapy development and production.

© 2021 Merck KGaA, Darmstadt, Germany and/or its affiliates. All Rights Reserved.

Reproduction of any materials from the site is strictly forbidden without permission.