I've "Googled" a lot and there's some stuff for other products (Clariion & Celerra).
I didn't find any Nagios plugin or script for VNXe.
I got the vnxe_alert.mib but it's really not convenient at all.
According to that discussion thread, the VNXe only supports SNMP traps, so you aren't going to find a traditional polling-style Nagios plugin for it. There is also link to a MIB for the traps, in this thread, but I can't get it to load.
You can, however, set up snmptrapd and then use snmptt to translate traps into passive checks for nagios. It's a bit complicated, but it's doable. There are also some other options for getting snmp traps into nagios, shown on this Nagios docs page.
They also mention writing a wrapper around the UEMCLI output, but I don't think anyone has done this yet. I would expect to see it show up in the EMC category on Nagios Exchange.