The best way to decrease inflammation is to detoxify the body.  Yoga detoxifies by increasing the oxygenation, eliminating the carbon dioxide levels in the body and promoting lymphatic return.

Do you need to do a Yoga asana to get these benefits?
No, you can do deep, diaphramatic breaths ANYTIME.  However, when you combine three-dimensional breathing with aligned body movements, the effects of both are multiplied.