Auto closed when state "OK/UP"

[nol]

Hello there,
I actually got :
OTRS 3.2.9 connected to Nagios 3.
When I got a new state on my supervision (Critical or Warning), Nagios mails OTRS to open a ticket.
But, I would like to know how to close it when my state change to OK or UP. Moreover, how to retrieve the ticket number that was created?

Thanks