Alasdair Strokosch and Dougie Hall will both miss out after picking up injuries in the Calcutta Cup defeat to England last Saturday.
Back-row forward Strokosch - who will see specialists in Edinburgh today to examine the extent of an eye socket injury - is replaced by Robert Harley while Ross Ford comes in at hooker in place of Hall, missing with a knee injury.
However, Hall could yet feature and has been pencilled in as replacement number two with understudy Pat MacArthur, with a decision to come later this week.
Johnson said: "I had the pleasure of working with Robert on our tour last summer.
"He's big and aggressive and he's been knocking on the door for selection for a while. He deserves this chance as a reward for his club form.
"Italy's victory over France in Rome was well deserved and certainly didn't surprise us. It will be a true Test match this weekend and it would be great to have a big vocal Murrayfield crowd supporting the boys this weekend."
Glasgow forward Harley, 22, makes his first start at Murrayfield, having scored the winning try against Samoa on the Scots' tour of the South Pacific last summer.
Kelly Brown will retain the captaincy for the visit of the Azzurri after Johnson - who has declined to confirm if he will continue in the role for the entire competition - gave him the nod once more.
Strokosch, meanwhile, will see experts at Spire Murrayfield Hospital today to determine whether he can play any further part in the Championship after damaging his eye socket in the 38-18 defeat to the Auld Enemy.