Arab raiders had been probing southern Italy since the 7th century. They established an Emirate in Sicily in 842 and another at Bari in 847. Arab mercenaries had been fighting for several years in wars between Italian nobles. This led to a raid against Rome itself in 846 by a band of opportunistic Arab mercenaries, who were not numerous or organized enough to breach the city's Aurelian Wall - which was not a huge loss since they were able to load themselves down with booty from churches outside the walls. A second attempted raid in 849 was repulsed at Ostia.

Sicily was conquered by Norman forces (with the assistance of local partisans) in the late 11th century. Pogroms against the Arabs and local converts led to a Muslim rebellion which wasn't fully stamped out until the 1220s.

To answer the second part of your question, I think Renaud de Châtillon would be the closest a Christian came to even attack Mecca. If you watched the movie Kingdom of Heaven, you might remember this particular person as the redheaded ruler of Kerak. What the film never showed is that after attacking a muslim caravan during the 1180s, which caused a few skirmishes between the Kingdom of Jerusalem and Saladin, he went on to raid the Red sea coast, his goal being to burn down Mecca and Medina. Problem is, he was pretty much gone rogue in regards to the Kingdom of Jerusalem. His raids were not supported by then King, Baldwin IV. As a result, besides a few coastal villages he didn't raid much and his band of mercenaries were quickly captured and executed while he fled back to his castle.

To ask a very similar question, did the Ottoman capture of Otranto in 1480 pose a serious threat to the city of Rome itself?