AmE Punctuation

In the United States, would we technically omit the commas between the questions (like this)?

The questions "Who?" "What?" "When?" "Where?" "How?" and " Why?" need to be answered before we proceed with the investigation.

Alternatively, can italics do the trick too?

The questions Who? What? When? Where? How? and Why? need to be answered before we proceed with the investigation.

Thank you.