Effects of Proanthocyanidins on Adhesion, Growth, and Virulence of Highly Virulent Extraintestinal Pathogenic Escherichia coli Argue for Its Use to Treat Oropharyngeal Colonization and Prevent Ventilator-Associated Pneumonia.

OBJECTIVE: In the context of increasing microbial resistance and limited new antimicrobials, we aimed to study the antimicrobial effects of cranberry proanthocyanidin extracts on Escherichia coli growth, adhesion to epithelial cells, and lung infection. DESIGN: Experimental in vitro and in vivo investigation. SETTING: University research laboratory. SUBJECTS: Seventy-eight 6- to 8-week-old male Balb/C mice. INTERVENTIONS: In vitro, the effect of increasing concentrations of cranberry proanthocyanidin on bacterial growth of different clinical E. coli isolates was evaluated. Ex vivo, adhesion of E. coli to fresh human buccal epithelial cells was measured in the presence or absence of cranberry proanthocyanidin using microscopy. In vivo, lung bacterial count, pulmonary immune response (neutrophil murine chemokine keratinocyte-derived cytokine measurement and polymorphonuclear recruitment in bronchoalveolar lavage fluid), and lethality were evaluated in a pneumonia mouse model with E. coli precultured with or without cranberry proanthocyanidin. E. coli isolates originated from ventilated ICU patients with respiratory tract colonization or ventilator- associated pneumonia. They differed in number of virulence genes. MEASUREMENTS AND MAIN RESULTS: A significant inhibition of bacterial growth was observed with increasing concentration of cranberry proanthocyanidin, affecting both time to maximal growth and maximal growth rate (p<0.0001 for both). The minimal concentration at which this effect occurred was 250 µg/mL. Cranberry proanthocyanidin significantly reduced E. coli adhesion to fresh buccal epithelial cells by up to 80% (p<0.001). Bacterial counts in homogenized lungs and bronchoalveolar lavage fluid were decreased after cranberry proanthocyanidin exposition (p<0.05 and p<0.01, respectively). Cranberry proanthocyanidin also decreased KC concentrations and polymorphonuclear cell recruitment in bronchoalveolar lavage fluid (p<0.05 for both). At identical inoculum, mortality was reduced by more than half in mice inoculated with E. coli exposed to cranberry proanthocyanidin (p<0.01). CONCLUSION: Cranberry proanthocyanidins exhibit potent effects on growth, adhesion, and virulence of oropharyngeal and lung isolates of E. coli, suggesting that cranberry proanthocyanidin could be of clinical interest to reduce oropharyngeal colonization and prevent lung infection.

Deficient CD40-TRAF6 signaling in leukocytes prevents atherosclerosis by skewing the immune response toward an antiinflammatory profile.

The CD40-CD40 ligand (CD40L) signaling axis plays an important role in immunological pathways. Consequently, this dyad is involved in chronic inflammatory diseases, including atherosclerosis. Inhibition of CD40L in apolipoprotein E (Apoe)-deficient (Apoe(-/-)) mice not only reduced atherosclerosis but also conferred a clinically favorable plaque phenotype that was low in inflammation and high in fibrosis. Blockade of CD40L may not be therapeutically feasible, as long-term inhibition will compromise systemic immune responses. Conceivably, more targeted intervention strategies in CD40 signaling will have less deleterious side effects. We report that deficiency in hematopoietic CD40 reduces atherosclerosis and induces features of plaque stability. To elucidate the role of CD40-tumor necrosis factor receptor-associated factor (TRAF) signaling in atherosclerosis, we examined disease progression in mice deficient in CD40 and its associated signaling intermediates. Absence of CD40-TRAF6 but not CD40-TRAF2/3/5 signaling abolishes atherosclerosis and confers plaque fibrosis in Apoe(-/-) mice. Mice with defective CD40-TRAF6 signaling display a reduced blood count of Ly6C(high) monocytes, an impaired recruitment of Ly6C(+) monocytes to the arterial wall, and polarization of macrophages toward an antiinflammatory regulatory M2 signature. These data unveil a role for CD40-TRAF6, but not CD40-TRAF2/3/5, interactions in atherosclerosis and establish that targeting specific components of the CD40-CD40L pathway harbors the potential to achieve therapeutic effects in atherosclerosis.