Has anyone invaded Rome as an islamic faction? What were the consequences?

In my H/VH turkish campaign, I'm currently mopping up the venetians, and I'm looking to start planning my next war. It's probably a few turns off because I'm expecting mongol visitors in baghdad soon, however, the most logical next move for me is into the italian peninsula.

My strategy has been to expand across the northern coast of the mediteranian, aagean & adriatic seas, occupying coastal towns, while forming a strong alliance with the hugarians to the north to serve as a buffer against invasion by other factions. I also have a very important alliance with the French.

However, if I get into a war with the papal states, will I incur a penalty in my relations with the french or hungarians? Neither has a papal states alliance, but I'm not sure if there would be other consequences.