Surface chemistry modification of silica nanoparticles alters the activation of monocytes.

Nanoparticles (NPs) interaction with immune system is a growing topic of study. Bare and amine grafted silica NPs effects on monocytes/macrophages cells were analyzed by flow cytometry, MTT test and LIVE/DEAD viability/cytotoxicity assay. Bare silica NPs inhibited proliferation and induced monocyte/macrophages activation (increasing CD40/CD80 expression besides pro-inflammatory cytokines and nitrite secretion).

Superantigens Impair Monocytes/Macrophages Inducing Cell Death and Inefficient Activation.

Bacterial superantigens (SAgs) are enterotoxins that bind to MHC-II and TCR molecules, activating as much as 20% of the T cell population and promoting a cytokine storm which enhances susceptibility to endotoxic shock, causing immunosuppression, and hindering the immune response against bacterial infection. Since monocytes/macrophages are one of the first cells SAgs find in infected host and considering the effect these cells have on directing the immune response, here, we investigated the effect of four non-classical SAgs of the staphylococcal operon, namely, SEG, SEI, SEO, and SEM on monocytic-macrophagic cells, in the absence of T cells. We also analyzed the molecular targets on APCs which could mediate SAg effects.

Evidence of size-dependent effect of silica micro- and nano-particles on basal and specialized monocyte functions.

Aim: To analyze the effect of silica particles on monocyte/macrophage functions.

Materials & Methods: Silica micro- and nanoparticles were obtained by the Stöber method. Their effect on monocyte/macrophage proliferation, activation, membrane integrity and metabolic activity were determined.

Peptidoglycan recognition protein-peptidoglycan complexes increase monocyte/macrophage activation and enhance the inflammatory response.

Peptidoglycan recognition proteins (PGRP) are pattern recognition receptors that can bind or hydrolyse peptidoglycan (PGN). Four human PGRP have been described: PGRP-S, PGRP-L, PGRP-Iα and PGRP-Iβ. Mammalian PGRP-S has been implicated in intracellular destruction of bacteria by polymorphonuclear cells, PGRP-Iα and PGRP-Iβ have been found in keratinocytes and epithelial cells, and PGRP-L is a serum protein that hydrolyses PGN.