I agree that silos are a big part of the underlying cause of friction, whether between DBAs and Developers and Project Managers or other "functions" within IT. And most of the good ideas about how to break down that friction have already been stated, although I'd suggest lunch as an alternative to beer (I don't like beer, so I'm at a disadvantage on that one :ermm: ).
Over the course of my career I've worked Operations, Production Support, Development, DBA, Project Manager, Systems Analyst and Business Analyst. I've only occasionally run across an individual that was truly difficult to work with. The best advice I could give, based on what has worked for me, is to "be the change you want to see".
Want more respect? Act respectfully towards others. Need better communication? Check how you are communicating and look for ways to improve. Often we point out the faults in others to avoid seeing those same faults within ourselves (and yes, I include myself in this!)
I've noticed that when I'm complaining about the actions of someone else, nothing changes. Conversely, if instead I take action and change what I am doing, or I reach out to ask questions in a different way, the change percolates outward - sometimes with unexpected results.
I think this all boils down to: Take Action
Don't wait for the world to change. Go out and change it.
Here there be dragons...,