Dose-Dependent Effects of Endotoxin on Neurobehavioral Functions in Humans

Clinical and experimental evidence document that inflammation and increased peripheral cytokine levels are associated with depression-like symptoms and neuropsychological disturbances in humans. However, it remains unclear whether and to what extent cognitive functions like memory and attention are affected by and related to the dose of the inflammatory stimulus. Thus, in a cross-over, double-blind, experimental approach, healthy male volunteers were administered with either placebo or bacterial lipopolysaccharide (LPS) at doses of 0.4 (n = 18) or 0.8 ng/kg of body weight (n = 16). Pro- and anti-inflammatory cytokines, norephinephrine and cortisol concentrations were analyzed before and 1, 1.75, 3, 4, 6, and 24 h after injection. In addition, changes in mood and anxiety levels were determined together with working memory (n-back task) and long term memory performance (recall of emotional and neutral pictures of the International Affective Picture System). Endotoxin administration caused a profound transient physiological response with dose-related elevations in body temperature and heart rate, increases in plasma interleukin (IL)-6, IL-10, tumor necrosis factor (TNF)-α and IL-1 receptor antagonist (IL-1ra), salivary and plasma cortisol, and plasma norepinephrine. These changes were accompanied by dose-related decreased mood and increased anxiety levels. LPS administration did not affect accuracy in working memory performance but improved reaction time in the high-dose LPS condition compared to the control conditon. In contrast, long-term memory performance was impaired selectively for emotional stimuli after administration of the lower but not of the higher dose of LPS. These data suggest the existence of at least two counter-acting mechanisms, one promoting and one inhibiting cognitive performance during acute systemic inflammation

Candida albicans-epithelial interactions: dissecting the roles of active penetration, induced endocytosis and host factors on the infection process

International audienceCandida albicans frequently causes superficial infections by invading and damaging epithelial cells, but may also cause systemic infections by penetrating through epithelial barriers. C. albicans is a remarkable pathogen because it can invade epithelial cells via two distinct mechanisms: induced endocytosis, analogous to facultative intracellular enteropathogenic bacteria, and active penetration, similar to plant pathogenic fungi. Here we investigated the contributions of the two invasion routes of C. albicans to epithelial invasion. Using selective cellular inhibition approaches and differential fluorescence microscopy, we demonstrate that induced endocytosis contributes considerably to the early time points of invasion, while active penetration represents the dominant epithelial invasion route. Although induced endocytosis depends mainly on Als3-E–cadherin interactions, we observed E–cadherin independent induced endocytosis. Finally, we provide evidence of a protective role for serum factors in oral infection: human serum strongly inhibited C. albicans adhesion to, invasion and damage of oral epithelial cell

Clotrimazole Dampens Vaginal Inflammation and Neutrophil Infiltration in Response to Candida albicans Infection

The pathology of vulvovaginal candidiasis (VVC) caused by Candida albicans is associated with a nonprotective inflammatory response and is frequently treated with clotrimazole. We investigated the mechanisms by which clotrimazole resolves VVC. Low levels of clotrimazole, which do not block fungal growth, inhibit expression of a “danger response” transcription factor, c-Fos, block production of proinflammatory cytokines, and inhibit neutrophil infiltration to the site of infection

Adhesion, invasion and damage of oral epithelial cells by <i>C. albicans</i> in the presence of serum.

<p>(A) Adhesion of viable <i>C. albicans</i> cells to oral epithelial cells in cell culture medium supplemented with 10% human [hSerum] or fetal bovine serum [FBS]; (+) heat-treated; (−) untreated; ctr, <i>C. albicans</i> without serum. (B) Induced endocytosis of thimerosal-inactivated <i>C. albicans</i> hyphae. Either oral epithelial cells were supplemented with untreated and heat-treated 10% hSerum or FBS [EC] or <i>C. albicans</i> hyphae [<i>Ca</i>] were pre-incubated with untreated or heat-treated 40% serum; ctr killed hyphae without serum. (C) Cell damage of epithelial monolayers caused by viable <i>C. albicans</i> cells after 24 h in cell culture medium supplemented with untreated or heat-treated 10% hSerum or FBS compared to <i>C. albicans</i> infection with the addition of 1% serum (ctr). **, significant difference compared to control adhesion, invasion or damage (p≤0.01).</p

Differential

<p><b>invasion of TR-146 or HeLa epithelial cells by </b><b><i>C. albicans</i></b><b>.</b> (A) Oral TR-146 or HeLa epithelial cells were co-incubated with 10⁵<i>C. albicans</i> cells (alive or thimerosal killed – Wt+Thim) for either 1, 2 or 3 h. (B) HeLa epithelial cells were co-incubated with 10⁵ indicated <i>C. albicans</i> strains (alive or thimerosal killed) for 3 h. Following fixation, samples were differentially stained and analyzed by fluorescence microscopy. The experiment was performed at least two times in duplicates. */**, indicates significant difference between cell lines (A) or between mutant and wild type (B) (<i>p<</i>0.05/<i>p<</i>0.01, respectively).</p

Candidalysin delivery to the invasion pocket is critical for host epithelial damage induced by <i>Candida albicans</i>

The human pathogenic fungus Candida albicans is a frequent cause of mucosal infections. Although the ability to transition from the yeast to the hypha morphology is essential for virulence, hypha formation and host cell invasion per se are not sufficient for the induction of epithelial damage. Rather, the hypha-associated peptide toxin, candidalysin, a product of the Ece1 polyprotein, is the critical damaging factor. While synthetic, exogenously added candidalysin is sufficient to damage epithelial cells, the level of damage does not reach the same level as invading C. albicans hyphae. Therefore, we hypothesized that a combination of fungal attributes is required to deliver candidalysin to the invasion pocket to enable the full damaging potential of C. albicans during infection. Utilizing a panel of C. albicans mutants with known virulence defects, we demonstrate that the full damage potential of C. albicans requires the coordinated delivery of candidalysin to the invasion pocket. This process requires appropriate epithelial adhesion, hyphal extension and invasion, high levels of ECE1 transcription, proper Ece1 processing, and secretion of candidalysin. To confirm candidalysin delivery, we generated camelid V(H)Hs (nanobodies) specific for candidalysin, and demonstrate localization and accumulation of the toxin only in C. albicans-induced invasion pockets. In summary, a defined combination of virulence attributes and cellular processes is critical for delivering candidalysin to the invasion pocket to enable the full damage potential of C. albicans during mucosal infection

Clotrimazole Dampens Vaginal Inflammation and Neutrophil Infiltration in Response to Candida albicans Infection

The pathology of vulvovaginal candidiasis (VVC) caused by Candida albicans is associated with a nonprotective inflammatory response and is frequently treated with clotrimazole. We investigated the mechanisms by which clotrimazole resolves VVC. Low levels of clotrimazole, which do not block fungal growth, inhibit expression of a “danger response” transcription factor, c-Fos, block production of proinflammatory cytokines, and inhibit neutrophil infiltration to the site of infection