Effect of human defensins on lactobacilli and liposomes.
OBJECTIVE
To study the effect of human β-defensins (HBD-1 and HBD-2) on lactobacilli membranes as well as on liposomes prepared from purified bacterial lipids.


RESULTS
Lactobacillus delbrueckii subsp. bulgaricus CIDCA 331 and Lact. delbrueckii subsp. lactis CIDCA 133 were grown in Man, Rogosa, Sharpe broth for 16 h at 37 °C. After being washed, micro-organisms were treated with 0.1-10 μg ml(-1) of HBD-1 and HBD-2 (30 min, 37 °C). Bacterial damage was determined by flow cytometry after propidium iodide staining. In parallel experiments, release of carboxyfluorescein from liposomes prepared from bacterial lipids was determined fluorometrically (excitation 485/20 nm, emission 528/20 nm) in the presence of HBD-1, HBD-2 or Nisin. Exposure of lactobacilli to HBD-2 resulted in a significant membrane permeabilization being Lact. delbrueckii subsp. bulgaricus CIDCA 331 the most susceptible strain. Liposomes prepared with lipids from strain CIDCA 133 were destabilized neither by HBD-1 nor by HBD-2, whereas liposomes derived from strain CIDCA 331 were susceptible to HBD-2 but not to HBD-1. Effect of defensins was strongly inhibited in the presence of NaCl, and the activity increased in water.


CONCLUSIONS
Results reported in the presented work indicate that lipid composition of bacterial membranes lead to a different interaction with cationic peptides such as defensins.


CONCLUSIONS
The results represent an advance in the understanding of the differential effect of HBDs on micro-organisms. Differences in susceptibility to anti-microbial peptides could modify the fate of micro-organisms after the interaction with host's cells.
Centro de Investigación y Desarrollo en Criotecnología de Alimentos, Conicet La Plata, Universidad Nacional de La Plata, La Plata, Argentina.
A A
AA
Hugo
E E
EE
Tymczyszyn
A
A
Gómez-Zavaglia
P F
PF
Pérez
D002462:Cell Membrane / Q000737:chemistry / Q000187:drug effects; D002463:Cell Membrane Permeability / Q000187:drug effects*; D005434:Flow Cytometry; D006801:Humans; D048668:Lactobacillus delbrueckii / Q000166:cytology / Q000187:drug effects*; D008055:Lipids / Q000737:chemistry; D008081:Liposomes / Q000737:chemistry*; D009561:Nisin / Q000494:pharmacology; D023083:beta-Defensins / Q000494:pharmacology*
D008055:Lipids; D008081:Liposomes; D023083:beta-Defensins; D009561:Nisin