Frédéric Féger

In the present report we have analyzed whether human normal cord blood-derived mast cells (CBMC) could interact with bacterial products, especially lipopolysaccharide (LPS) from Escherichia coli and peptidoglycan (PGN) from Staphylococcus aureus, known as Toll-like receptor (TLR) 4 and TLR2 agonists, respectively. We found that both LPS and PGN induced significant release of not only tumor necrosis factor-alpha (TNF-alpha), but also IL-5, IL-10 and IL-13 by human mast cells (MC). We also established that the stimulation of CBMC with LPS or with PGN is mediated through interactions with TLR4 or with TLR2, respectively. Thus, our data indicate that activation of either TLR2 or TLR4 pathway may lead to a pro-Th2 immune response. However, the release of TNF-alpha induced by LPS, conversely to PGN, required the priming of CBMC by IL-4 and the presence of serum components, in particular soluble CD14. Of interest, stimulation by PGN, but not by LPS, induced release of histamine by human MC. Altogether, these findings provide the first evidence that human MC differentially respond towards bacterial components, and that their responses depend on TLR pathways and reveal human specificities in the pattern of cytokine production.

OBJECTIVE: Whether cardiac ventricles can acutely dilate during septic myocardial dysfunction. DESIGN: A prospective echocardiographic study was performed to assess changes of left ventricular dimensions over time in patients with septic shock. SETTINGS: A 20-bed surgical intensive care unit of Pitié-Salpêtrière university hospital in Paris. PATIENTS: Forty-five patients were studied over the first 10 days of septic shock. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Left ventricular end-diastolic area (LVEDA), fractional area change (FAC), velocity time integral of the aortic flow, echocardiographic indices of left ventricular relaxation, and cardiac troponin I (cTnI) were measured at day 1, 2, 3, 4, 7, and 10. Three groups were defined: 29 patients without increased cTnI and cardiac impairment (group 1), eight patients with increased cTnI and left systolic ventricular dysfunction (group 2), and eight patients with increased cTnI and isolated impairment of left ventricular relaxation (group 3). At day 1, LVEDA was significantly higher in group 2 (13 +/- 3 cm/m, p < 0.05) compared with groups 1 (10 +/- 2 cm/m) and 3 (11 +/- 2 cm/m). LVEDA did not change in groups 1 and 3. In group 2, LVEDA and FAC returned within 10 days to values observed in groups 1 and 2. A significant correlation was found between aortic velocity time integral and LVDEA (r =.78, p = 0.022) and FAC (r =.89, p = 0.003) only in group 2. CONCLUSIONS: Acute and reversible left ventricular dilation accompanies septic shock-induced systolic left ventricular dysfunction. When septic myocardial abnormalities are limited to reversible impairment of left ventricular relaxation, left ventricular dimensions remain unchanged.

Adult's mastocytosis is usually associated with persistent systemic involvement and c-kit 816 mutation, while pediatrics disease is mostly limited to the skin and often resolves spontaneously. We prospectively included 142 adult patients with histologically proven mastocytosis. We compared phenotypic and genotypic features of adults patients whose disease started during childhood (Group 1, n = 28) with those of patients whose disease started at adult's age (Group 2, n = 114). Genotypic analysis was performed on skin biopsy by sequencing of c-kit exons 17 and 8 to 13. According to WHO classification, the percentage of systemic disease was similar (75 vs. 73%) in 2 groups. C-kit 816 mutation was found in 42% and 77% of patients in groups 1 and 2, respectively (p<0.001). 816 c-kit mutation was associated with systemic mastocytosis in group 2 (87% of patients with systemic mastocytosis vs. 45% with cutaneous mastocytosis, p = 0.0001). Other c-kit activating mutations were found in 23% of patients with mastocytosis' onset before the age of 5, 0% between 6 and 15 years and 2% at adults' age (p<0.001). In conclusion, pathogenesis of mastocytosis significantly differs according to the age of disease's onset. Our data may have major therapeutic relevance when considering c-kit-targeted therapy.