Journal Article

Adhesins, Bacterial; Animals; Antigens, CD46; Bacteremia; Bacterial Outer Membrane Proteins; Bacterial Proteins; Bacterial Translocation; Bioware; Blood-Brain Barrier; Central Nervous System; Disease Progression; Female; Luminescent Measurements; Luminescent Proteins; Male; Meningitis, Meningococcal; Meningococcal Infections; Mice; Mice, Transgenic; Nasal Cavity; pXen-13; Recombinant Fusion Proteins; Respiratory System; Sepsis; Thyroid Gland

Neisseria meningitidis is a human pathogen that causes septicemia and meningitis with high mortality. The disease progression is rapid and much remains unknown about the disease process. The understanding of disease development is crucial for development of novel therapeutic strategies and vaccines against meningococcal disease. The use of bioluminescent imaging combined with a mouse disease model allowed us to investigate the progression of meningococcal sepsis over time. Injection of bacteria in blood demonstrated waves of bacterial clearance and growth, which selected for Opa-expressing bacteria, indicating the importance of this bacterial protein. Further, N. meningitidis accumulated in the thyroid gland, while thyroid hormone T4 levels decreased. Bacteria reached the mucosal surfaces of the upper respiratory tract, which required expression of the meningococcal PilC1 adhesin. Surprisingly, PilC1 was dispensable for meningococcal growth in blood and for crossing of the blood-brain barrier, indicating that the major role of PilC1 is to interact with mucosal surfaces. This in vivo study reveals disease dynamics and organ targeting during meningococcal disease and presents a potent tool for further investigations of meningococcal pathogenesis and vaccines in vivo. This might lead to development of new strategies to improve the outcome of meningococcal disease in human patients.

Journal Article

Animals; Arthritis, Experimental; Bioware; Chemotaxis, Leukocyte; Humans; Inflammation; Mice; Mice, Transgenic; Neutrophils; p38 Mitogen-Activated Protein Kinases; Phosphatidylinositol 3-Kinases; Phosphatidylinositol Phosphates; Protein Transport; PTEN Phosphohydrolase; Xen29

Neutrophils encounter and 'prioritize' many chemoattractants in their pursuit of bacteria. Here we tested the possibility that the phosphatase PTEN is responsible for the prioritization of chemoattractants. Neutrophils induced chemotaxis by two separate pathways, the phosphatidylinositol-3-OH kinase (PI(3)K) phosphatase and tensin homolog (PTEN) pathway, and the p38 mitogen-activated protein kinase pathway, with the p38 pathway dominating over the PI(3)K pathway. Pten(-/-) neutrophils could not prioritize chemoattractants and were 'distracted' by chemokines when moving toward bacterial chemoattractants. In opposing gradients, PTEN became distributed throughout the cell circumference, which inhibited all PI(3)K activity, thus permitting 'preferential' migration toward bacterial products via phospholipase A(2) and p38. Such prioritization was defective in Pten(-/-) neutrophils, which resulted in defective bacterial clearance in vivo. Our data identify a PTEN-dependent mechanism in neutrophils to prioritize, 'triage' and integrate responses to multiple chemotactic cues.

Journal Article

IVIS, Xen29, Xen 29, Staphylococcus aureus Xen29

Nitric oxide (NO) generated by vascular NO synthases can exert anti-inflammatory effects, partly through its ability to decrease leukocyte recruitment. Inorganic nitrate and nitrite, from endogenous or dietary sources, have emerged as alternative substrates for NO formation in mammals. Bioactivation of nitrate is believed to require initial reduction to nitrite by oral commensal bacteria. Here we investigated the effects of inorganic nitrate and nitrite on leukocyte recruitment in microvascular inflammation and in NSAID-induced small-intestinal injury. We show that leukocyte emigration in response to the proinflammatory chemokine MIP-2 is reduced by 70% after 7days of dietary nitrate supplementation as well as by acute intravenous nitrite administration. Nitrite also reduced leukocyte adhesion to a similar extent and this effect was inhibited by the soluble guanylyl cyclase inhibitor ODQ, whereas the effect on emigrated leukocytes was not altered by this treatment. Further studies in TNF-alpha-stimulated endothelial cells revealed that nitrite dose-dependently reduced the expression of ICAM-1. In rats and mice subjected to a challenge with diclofenac, dietary nitrate prevented the increase in myeloperoxidase and P-selectin levels in small-intestinal tissue. Antiseptic mouthwash, which eliminates oral nitrate reduction, markedly blunted the protective effect of dietary nitrate on P-selectin levels. Despite attenuation of the acute immune response, the overall ability to clear an infection with Staphylococcus aureus was not suppressed by dietary nitrate as revealed by noninvasive IVIS imaging. We conclude that dietary nitrate markedly reduces leukocyte recruitment to inflammation in a process involving attenuation of P-selectin and ICAM-1 upregulation. Bioactivation of dietary nitrate requires intermediate formation of nitrite by oral nitrate-reducing bacteria and then probably further reduction to NO and other bioactive nitrogen oxides in the tissues.

Journal Article

Cardiovascular disease; in vivo imaging; atherosclerosis; magnetic resonance imaging; thrombosis; myocardial infarction; diagnostic imaging; molecular imaging

No abstract available.

Journal Article

HCT-116-luc2, IVIS, Bioware, HCT116-luc2

Non-thermal plasma (NTP) is generated by ionizing neutral gas molecules/atoms leading to a highly reactive gas at ambient temperature containing excited molecules, reactive species and generating transient electric fields. Given its potential to interact with tissue or cells without a significant temperature increase, NTP appears as a promising approach for the treatment of various diseases including cancer. The aim of our study was to evaluate the interest of NTP both in vitro and in vivo. To this end, we evaluated the antitumor activity of NTP in vitro on two human cancer cell lines (glioblastoma U87MG and colorectal carcinoma HCT-116). Our data showed that NTP generated a large amount of reactive oxygen species (ROS), leading to the formation of DNA damages. This resulted in a multiphase cell cycle arrest and a subsequent apoptosis induction. In addition, in vivo experiments on U87MG bearing mice showed that NTP induced a reduction of bioluminescence and tumor volume as compared to nontreated mice. An induction of apoptosis was also observed together with an accumulation of cells in S phase of the cell cycle suggesting an arrest of tumor proliferation. In conclusion, we demonstrated here that the potential of NTP to generate ROS renders this strategy particularly promising in the context of tumor treatment.