Changed expression of leukocyte adhesion molecules and increased production of reactive oxygen species caused by Streptococcus pyogenes in human whole blood

Abstract

To elucidate the innate immune responses to group A streptococci (GAS) important in the pathophysiology of sepsis, flow cytometric techniques were applied to study the effects of live and heat-inactivated GAS, including their particulate and soluble components, on the expression of leukocyte adhesion molecules CD11b (Mac-1) and CD62L (L-selectin), and leukocyte production of reactive oxygen species (ROS) in human whole blood. GAS caused marked time- and concentration-dependent increases in CD11b and ROS, while CD62L was downregulated. Live and heat-inactivated GAS induced similar changes in leukocyte adhesion molecules, whereas ROS production induced by heat-inactivated GAS (and its particulate fraction) was 4 (2.5)-fold higher than with live GAS. Leukocyte nitric oxide production (24 h) was not enhanced. Although GAS proved a more potent inducer of ROS production, leukocyte responses to GAS were similar to those reported for lipolysaccharides, indicating that Gram-positive and Gram-negative bacteria activate common pathways in the inflammatory response. High ROS production may contribute to tissue damage caused by GAS.

Leukocyte-platelet interaction in pregnancies complicated with preeclampsia

“…We analyzed both the percentage of leukocytes expressing the ligand as well as the fluorescence intensity in absolute units; molecular equivalents of soluble fluorochrome (MESF) of the attached antibody as the difference between isotype control and the antibody of interest. The PSGL-1 antibody and isotype control, both FITC-conjugated, were delivered from Ancell Corporation, Bayport, MN, USA and the method for PSGL-1 analysis was adopted from Saetre et al [21] Beads for the standard curve of MESF units were from Bangs Laboratories Inc, Fisher, IN, USA.…”

Responses of microglia in vitro to the gram-positive bacterial component, lipoteichoic acid

“…Along with morphological changes, expressions of cell surface molecules such as MHC II and CR3 on the peripheral immune cells were also significantly affected by the gram-positive bacteria and their component, LTA (Carratelli et al, 1996;Saetre et al, 2000;Kolb-Maurer et al, 2000;Jorgensen et al, 2001). This study has demonstrated that just like in the peripheral immune cells, LTA from S. aureus markedly upregulated the surface expression of MHC class II molecules on microglia in vitro.…”

“…These receptors can be modulated by their ligands from the gram-positive bacterial cell walls, such as streptococcal LTA, which significantly increased the expression of complement receptor type 3 on human monocytes (Carratelli et al, 1996) or whole blood leukocytes (Saetre et al, 2000) and CD14 on whole-blood monocytes (Landmann et al, 1996;Saetre et al, 2000;Jorgensen et al, 2001). The modulation of scavenger receptor by LPS has also been evidenced in primary and elicited mouse peritoneal macrophages as well as the J774A.1 and RAW 264.7 mouse macrophage lines (Fitzgerald et al, 2000).…”

Superoxide anions produced by Streptococcus pyogenes group A-stimulated keratinocytes are responsible for cellular necrosis and bacterial growth inhibition

“…We showed that keratinocytes are able to produce ROS and this finding is consistent with previous work demonstrating that S. pyogenes is able to induce the production of ROS by HeLa cells and human leukocytes. 29,30 Moreover, transcriptional studies with macrophages infected with GAS demonstrated up-regulation of the p47phox gene encoding a component of the NADPH oxidase (Ncf1), further Figure 5. GAS induces cell death by stimulating O À 2 production.…”