Tài liệu Báo cáo khoa học: The antibacterial and antifungal properties of trappin-2 (pre-elafin) do

The antibacterial and antifungal properties of trappin-2

(pre-elafin) do not depend on its protease inhibitory

function

Ke´ vin Baranger, Marie-Louise Zani, Jacques Chandenier, Sandrine Dallet-Choisy and

Thierry Moreau

INSERM U618, Universite´ Franc¸ois Rabelais, Tours, France

Protease inhibitors of the chelonianin family, including

secretory leucocyte proteinase inhibitor (SLPI), elafin

and its active precursor trappin-2, are thought to be

important in protecting the lungs against damage by

the neutrophil serine proteases, human neutrophil elas￾tase, proteinase 3 and cathepsin G [1]. SLPI and ela￾fin ⁄trappin-2 are structurally related in that both have

a fold with a four-disulfide core, the whey acidic pro￾tein (WAP) domain involved in protease inhibition

[2,3]. Human SLPI is an unglycosylated, basic

(pI 9.5) 11.7 kDa protein that is synthesized at

many mucosal surfaces, including the lungs. It has a

high affinity for elastase and cathepsin G and has two

WAP domains, each of which is homologous to elafin.

Elafin corresponds to the C-terminal inhibitory domain

(57 residues) of trappin-2 (also called pre-elafin) which,

Keywords

antifungal activity; antimicrobial activity;

serine protease inhibitors; trappin-2; WAP

protein

Correspondence

T. Moreau, INSERM U618 Prote´ ases et

Vectorisation Pulmonaires, IFR 135,

Imagerie Fonctionnelle, University Franc¸ois

Rabelais, 10 Boulevard Tonnelle´,

37032 Tours, Cedex, France

Fax: +33 247 366 046

Tel: +33 2 4736 6177

E-mail: [email protected]

(Received 8 January 2008, revised 18

February 2008, accepted 22 February 2008)

doi:10.1111/j.1742-4658.2008.06355.x

Trappin-2 (also known as pre-elafin) is an endogenous inhibitor of neutro￾phil serine proteases and is involved in the control of excess proteolysis,

especially in inflammatory events, along with the structurally related secre￾tory leucocyte proteinase inhibitor. Secretory leucocyte proteinase inhibitor

has been shown to have antibacterial and antifungal properties, whereas

recent data indicate that trappin-2 has antimicrobial activity against Pseu￾domonas aeruginosa and Staphylococcus aureus. In the present study, we

tested the antibacterial properties of trappin-2 towards other respiratory

pathogens. We found that trappin-2, at concentrations of 5–20 lm, has

significant activity against Klebsiella pneumoniae, Haemophilus influenzae,

Streptococcus pneumoniae, Branhamella catarrhalis and the pathogenic

fungi Aspergillus fumigatus and Candida albicans, in addition to P. aerugin￾osa and S. aureus. A similar antimicrobial activity was observed with

trappin-2 A62D ⁄M63L, a trappin-2 variant that has lost its antiprotease

properties, indicating that trappin-2 exerts its antibacterial effects through

mechanisms independent from its intrinsic antiprotease capacity. Further￾more, the antibacterial and antifungal activities of trappin-2 were sensitive

to NaCl and heparin, demonstrating that its mechanism of action is most

probably dependent on its cationic nature. This enables trappin-2 to inter￾act with the membranes of target organisms and disrupt them, as shown

by our scanning electron microscopy analyses. Thus, trappin-2 not only

provides an antiprotease shield, but also may play an important role in the

innate defense of the human lungs and mucosae against pathogenic micro￾organisms.

Abbreviations

AEBSF, 4-(2-aminoethyl)benzenesulfonyl fluoride; CFU, colony forming unit; MED, minimum effective dose; SEM, scanning electron

microscopy; SLPI, secretory leucocyte proteinase inhibitor; WAP, whey acidic protein.

2008 FEBS Journal 275 (2008) 2008–2020 ª 2008 The Authors Journal compilation ª 2008 FEBS