Modelling human choices: MADeM and decision‑making

Research supported by FAPESP 2015/50122-0 and DFG-GRTK 1740/2. RP and AR are also part of the Research, Innovation and Dissemination Center for Neuromathematics FAPESP grant (2013/07699-0). RP is supported by a FAPESP scholarship (2013/25667-8). ACR is partially supported by a CNPq fellowship (grant 306251/2014-0)

Cathelicidin and PMB neutralize endotoxins by multifactorial mechanisms including LPS interaction and targeting of host cell membranes

Antimicrobial peptides (AMPs) contribute to an effective protection against infections. The antibacterial function of AMPs depends on their interactions with microbial membranes and lipids, such as lipopolysaccharide (LPS; endotoxin). Hyperinflammation induced by endotoxin is a key factor in bacterial sepsis and many other human diseases. Here, we provide a comprehensive profile of peptide-mediated LPS neutralization by systematic analysis of the effects of a set of AMPs and the peptide antibiotic polymyxin B (PMB) on the physicochemistry of endotoxin, macrophage activation, and lethality in mice. Mechanistic studies revealed that the host defense peptide LL-32 and PMB each reduce LPS-mediated activation also via a direct interaction of the peptides with the host cell. As a biophysical basis, we demonstrate modifications of the structure of cholesterol-rich membrane domains and the association of glycosylphosphatidylinositol (GPI)-anchored proteins. Our discovery of a host cell–directed mechanism of immune control contributes an important aspect in the development and therapeutic use of AMPs

Cathelicidin and PMB neutralize endotoxins by multifactorial mechanisms including LPS interaction and targeting of host cell membranes

Antimicrobial peptides (AMPs) contribute to an effective protection against infections. The antibacterial function of AMPs depends on their interactions with microbial membranes and lipids, such as lipopolysaccharide (LPS; endotoxin). Hyperinflammation induced by endotoxin is a key factor in bacterial sepsis and many other human diseases. Here, we provide a comprehensive profile of peptide-mediated LPS neutralization by systematic analysis of the effects of a set of AMPs and the peptide antibiotic polymyxin B (PMB) on the physicochemistry of endotoxin, macrophage activation, and lethality in mice. Mechanistic studies revealed that the host defense peptide LL-32 and PMB each reduce LPS-mediated activation also via a direct interaction of the peptides with the host cell. As a biophysical basis, we demonstrate modifications of the structure of cholesterol-rich membrane domains and the association of glycosylphosphatidylinositol (GPI)-anchored proteins. Our discovery of a host cell-directed mechanism of immune control contributes an important aspect in the development and therapeutic use of AMPs

The antimicrobial peptide cathelicidin and polymyxin B neutralize endotoxins by a multifactorial mechanism including not only direct LPS-interaction but also targeting of host cell membrane domains

Antimicrobial peptides (AMPs) contribute to an effective protection against infections. The antibacterial function of AMPs depends on their interactions with microbial membranes and lipids, such as lipopolysaccharide (LPS; endotoxin). Hyperinflammation induced by endotoxin is a key factor in bacterial sepsis and many other human diseases. Here, we provide a comprehensive profile of peptide-mediated LPS neutralization by systematic analysis of the effects of a set of AMPs and the peptide antibiotic polymyxin B (PMB) on the physicochemistry of endotoxin, macrophage activation, and lethality in mice. Mechanistic studies revealed that the host defense peptide LL-32 and PMB each reduce LPS-mediated activation also via a direct interaction of the peptides with the host cell. As a biophysical basis, we demonstrate modifications of the structure of cholesterol-rich membrane domains and the association of glycosylphosphatidylinositol (GPI)-anchored proteins. Our discovery of a host cell-directed mechanism of immune control contributes an important aspect in the development and therapeutic use of AMPs

Altered cell-mediated immunity and increased postoperative infection rate in long-term alcoholic patients

Background: Preoperative alteration of T cell-mediated immunity as well as an altered immune response to surgical stress were found in long-term alcoholic patients. The aim of this study was to evaluate perioperative T cell-mediated immune parameters as well as cytokine release from whole blood cells after lipopolysaccharide stimulation and its association with postoperative infections. Methods: Fifty-four patients undergoing elective surgery of the aerodigestive tract were included in this prospective observational study. Long-term alcoholic patients (n = 31) were defined as having a daily ethanol consumption of at least 60 g and fulfilling the Diagnostic and Statistical Manual of Mental Disorders for either alcohol abuse or alcohol dependence. The nonalcoholic patients (n = 23) were defined as drinking less than 60 g ethanol/day. Blood samples to analyze the immune status were obtained on morning before surgery and on the morning of days 1, 3, and 5 after surgery. Results: Basic patient characteristics did not differ between groups. Before surgery, the T helper 1:T helper 2 ratio (Th1: Th2) was significantly lower (P < 0.01), whereas plasma interleukin 1β and lipopolysaccharide-stimulated interleukin 1ra from whole blood cells were increased in long-term alcoholic patients. After surgery, a significant suppression of the cytotoxic lymphocyte ratio (Tc1:Tc2), the interferon γ:interleukin 10 ratio from lipopolysaccharide-stimulated whole blood cells, and a significant increase of plasma interleukin 10 was observed. Long-term alcoholics had more frequent postoperative infections compared with nonalcoholic patients (54% vs. 26%; P = 0.03). Conclusions: T helper cell-mediated immunity was significantly suppressed before surgery and possibly led to inadequate cytotoxic lymphocyte and whole blood cell response in long-term alcoholic patients after surgery. This altered cell-mediated immunity might have accounted for the increased infection rate in long-term alcoholic patients after surgery