Treatment of an Interior Brick Wall

We (my wife and I) spend a great day cleaning 2 brick walls in our apartment, and it looks great!

The wall is about 100 years old and gets quite dusty.

We are in two opposing camps on this:

She is in the "leave it untreated" camp.

I would like to treat it with something but I do not like the look of polyurethane.

What would you recommend?

Thanks.

G.