Hi @denisbastia,
Have a look at this post for some information on a work-around, which involves creating a symbolic link from your files_dir (configured in config.inc.php) to your public files area. Note that this will permit Journal Managers to upload potentially malicious files – e.g. .php and .html, so there is some level of risk associated with it.
Regards,
Alec Smecher
Public Knowledge Project Team