No description available.

No description available.

No description available.

No description available.

C-reactive protein (CRP) is a member of the pentraxin family which opsonises S. pneumoniae through its binding to phosphorylcholine. In addition, CRP binds to Fcγ receptors: FcγRI with high affinity and, probably, FcγRIIA with lower affinity. Binding to FcγRIIA was suggested to depend on a polymorphism at residue 131 of the receptor, HH individuals being poorer binders compared to RR. To clarify the role of CRP binding to FcγRIIA and functional activities upon interaction, neutrophils from HH and RR individuals were incubated with CRP in the presence or absence of pneumococci type 3. No difference in activation as determined by IL-8 synthesis, respiratory burst and phagocytosis were seen between HH and RR donors. Since CRP increases its serum concentration up to 1000 fold above the normal level, we also compared acute-phase concentrations of CRP with normal levels for neutrophil functions. Normal (≤10 μg/ml) and acute-phase (10 - 100 μg/ml) levels increased IL-8 production in the presence or absence of pneumococci. A similar pattern was seen for extracellular reactive oxygen. There was a five-fold increase in DHR oxidation in neutrophils when CRP at 10 μg/ml was used, although this was reduced when CRP at 50 and 100 μg/ml was used in both HH and RR donors. Recombinant CRP also gave a similar pattern in which higher MFIs for DHR oxidation were obtained for CRP at 10 μg/ml. On average a two-fold increase in phagocytosis of pneumococci serotype 3 was obtained for both type of donors for CRP at 10 μg/ml. This effect was also reduced at acute-phase levels of CRP. The down-regulatory effects of CRP are thus selective for certain responses but do not require phagocytosis since CRP at 50 - 100 μg/ml could also inhibit PMA activation. The ability of CRP to bind to Fcγ-receptors using surface plasmon resonance was evaluated, but there was no evidence of CRP binding to FcγRIIA, RIIB or RIII Serum amyloid P component showed strong binding to FcγRIII and weak binding to FcγRIIA and RIIB. A glycosylated form of the Fc receptor may be required for binding

Pathogenic Yersinia species can avoid phagocytosis by virtue of a type III secretion system that injects protein effectors into host cells, where they hijack phagocytic signalling. YopO is a multi domain protein known to contribute to anti-phagocytosis. It has a N-terminal plasma membrane localisation domain, a serine/threonine kinase activity, a Rho/Rac-family binding domain (RBD) and a C-terminal actin-binding domain. The aim of this study was to understand the previously unknown mechanism of YopO-mediated anti-phagocytosis.

During pregnancy, maternal uterine spiral arteries are remodelled from minimal flow, high resistance vessels into large diameter, low resistance, high flow vessels. This change is crucial for delivery of adequate blood supply to the developing fetus, and is impaired in pregnancies complicated by pre-eclampsia. In early pregnancy, fetal trophoblasts invade into the decidua and remodel the spiral arteries. However, decidual natural killer (dNK) cells accumulate around spiral arteries and are present ahead of trophoblast invasion. Their presence is continuous during trophoblast invasion and spiral artery remodelling. A functional role for dNK in remodelling has not yet been defined. Measurement of uterine artery resistance indices (RI), by Doppler ultrasound at 9-14 weeks of gestation, was used to identify pregnancies with <1 % risk (normal RI) of developing pre-eClampsia or a >21 % risk (high RI). Following surgical termination of pregnancy, CD56+ dNK cells were isolated and comparisons made between cells from normal and high RI pregnancies. dNK cell-secreted factors and receptor expression were characterised by proteome profiler arrays, multiplex assays, flow cytometry and western blot analysis. Differences between the two groups were detected in several factors, including angiogenin, endostatin, hepatocyte growth factor (HGF), placental growth factor (PIG F), the soluble interleukin-2 receptor (sIL-2R), active matrix metalloproteinases (MMPs), tumour necrosis factor (TNF)-α, Fas ligand (FasL) and TNF-related apoptosis inducing ligand (TRAIL). dNK effects on trophoblasts and vascular cells were investigated by eo- culture studies to model the interactions at the maternal-fetal interface. Normal RI dNK solube factors were able to promote trophoblast motility (an important component of invasion), to a greater extent than high RI dNK, and a function for dNK-secreted HGF in promoting trophoblast motility was determined. Normal RI dNK caused destabilisation of endothelial cell tube-like structures, partly through TNF-α, whereas this effect was not seen with high RI dNK. Normal RI dNK cells also induced vascular cell apoptosis partly via FasL, while high RI dNK cells did not. These studies demonstrate a functional role for dNK in regulating trophoblast motility and vascular cell remodelling, events of importance in a successful pregnancy. The ability of dNK to regulate these events in pregnancies at higher risk of pre-eclampsia is impaired, which may contribute to the poor remodelling seen in these pregnancies.

No description available.

No description available.

The p21-activated kinases (PAKs) are a family of serine/threonine kinases that are activated by the Rho GTPases, Rac1-3, Cdc42, Chp, TC10 and Wrch-1, as well as a number of lipids and PAK-interacting proteins. PAKs have been implicated in a variety of cellular processes including cell polarisation, migration, chemotaxis and gene transcription. The aim of this study was to determine the regulation and function of PAK1, using bone marrow-derived macrophages (BMMs) as a model system. CSF-1 stimulation of BMMs induced rapid phosphorylation and activation of PAK1, and CSF-1 and TNFa also promoted an increase in PAK1 protein levels after 2 to 5 hours. The rise in PAK1 protein was not due to changes in gene transcription, mRNA translation or reduced proteasomal degradation. Wildtype and PAK1"7" BMMs were compared to determine the roles of PAK1 in a number of macrophage functions. PAK1 was required for maximal ERK, p38 and JNK activation in response to CSF-1 although it did not appear to signal via c-Raf or MEK1. PAK1 phosphorylated Op18 and LIMK downstream of CSF-1, which regulate microtubule and actin reorganisation respectively. PAK1 also regulated MLC phosphorylation although this was not a CSF-1-induced response. PAK1_/" BMMs adhered more rapidly than WT BMMs and transiently spread to a greater area than WT BMMs. PAK1 promotion of ERK activity at the lamellipodial edge was required for the stability of lamellipodial extension during cell spreading with a greater number of smaller lamellipodia produced in PAK1"7" BMMs compared to WT BMMs. However, PAK2, active Cdc42, total ERK, £-PIX and Rac1 all localised normally at the cell periphery in spreading PAK1"7" BMMs. PAK1 was also required for membrane ruffling after CSF-1 stimulation but was dispensable for macrophage polarisation, migration and chemotaxis towards CSF-1. PAK1, therefore, contributes to CSF-1 and cell adhesion induced signalling in macrophages.