Evidence for the detection of non-endotoxin pyrogens by the whole blood monocyte activation test.

Threats of pyrogenicity were discovered more than a century ago. Measures to determine the safety of parenterals and, more recently, medical devices and cell therapies for human use have been in place for 70 years. Currently, there are three testing possibilities available: the Rabbit Pyrogen Test, the Limulus Amebocyte Lysate test (Bacterial Endotoxin Test), and test systems using human whole blood or human monocytes, called Monocyte Activation Test (MAT).

Systematic review of membrane components of gram-positive bacteria responsible as pyrogens for inducing human monocyte/macrophage cytokine release.

Fifty years after the elucidation of lipopolysaccharides (LPS, endotoxin) as the principal structure of Gram-negative bacteria activating the human immune system, its Gram-positive counterpart is still under debate. Pyrogen tests based on the human monocyte activation have been validated for LPS detection as an alternative to the rabbit test and, increasingly, the limulus amebocyte lysate test. For full replacement, international validations with non-endotoxin pyrogens are in preparation.

Anti-inflammatory capacity of selected lactobacilli in experimental colitis is driven by NOD2-mediated recognition of a specific peptidoglycan-derived muropeptide.

Background And Aims: Inflammatory bowel disease (IBD) has been linked to a loss of tolerance towards the resident microflora. Therapeutic use of probiotics is known to be strain specific, but precise mechanisms remain unclear. The role of NOD2 signalling and the protective effect of Lactobacillus peptidoglycan (PGN) and derived muropeptides in experimental colitis were evaluated.

Different Staphylococcus aureus whole bacteria mutated in putative pro-inflammatory membrane components have similar cytokine inducing activity.

The role of the different major cell wall components of Gram-positive bacteria for immune stimulation is controversial. We thus compared the cytokine inducing capacity of different Staphylococcus aureus (SA) mutants lacking either lipoproteins (SA 113Δlgt), or wall teichoic acids (WTA) (ΔTA), or possessing a reduced d-alanine content in lipoteichoic acid (LTA) (SA 113Δdlt) to its corresponding wildtype (SA 113wt). Inactivated whole bacteria and their purified cell wall components peptidoglycan and LTA, were used to stimulate human whole blood and macrophages from TLR2 knock-out mice.

D-alanyl ester depletion of teichoic acids in Lactobacillus reuteri 100-23 results in impaired colonization of the mouse gastrointestinal tract.

The dlt operon of Gram-positive bacteria encodes proteins required for the incorporation of D-alanine esters into cell wall-associated teichoic acids (TA). D-alanylation of TA has been shown to be important for acid tolerance, resistance to antimicrobial peptides, adhesion, biofilm formation, and virulence of a variety of pathogenic organisms. The aim of this study was to determine the importance of D-alanylation for colonization of the gastrointestinal tract by Lactobacillus reuteri 100-23.