Athanasius of Alexandria

It did not say, "He remedied our infirmities," lest, as being external to the body and only healing it, as he has always done, he should leave people subject still to death. Rather, he carries our infirmities, and he himself bears our sins, that it might be shown that he has become human for us, and that the body that in him bore them was his own body.

Discourses Against the Arians 3.31 ↗

Jerome

But he was wounded for our transgressions, he was bruised for our iniquities: the chastisement of our peace was upon him, and with his stripes we are healed. LXX: But he was wounded for our sins, and he was weakened for our iniquities. He was wounded for our iniquities, saying in the psalm: They have dug my hands and my feet (Ps. XXI, 18), so that with his wound he might heal our wounds, and he was crushed, or afflicted because of our sins, so that he became a curse for us, to deliver us from the curse. …

Commentary on Isaiah ↗

Gregory the Dialogist

Kish, who is called harsh, signifies not only his elect, but also the Redeemer himself. For no one was harsher toward himself than he. For the prophet, indicating the severity of this harshness, says: "Truly he himself bore our infirmities, and he himself carried our sorrows" (Isa. 53:4). For to die is not to suffer for mortals, who are subject to the suffering of a condemned nature. …

Six Books On 1 Kings 4:80 ↗

Thomas Aquinas

But he was wounded. Here he sets out the fruit of his humiliation or of his passion. And first, he assigns the moving reason: but he was, not as we thought, but wounded, by thorns, nails, and lance, for our iniquities, taking them away, he was bruised, by scourges and blows. Or he was wounded, as to where the previous verse says: he was struck; he was bruised, as to where it says: afflicted: the breath of our mouth, Christ the Lord, is taken in our sins (Lam 4:20). …

Commentary on Isaiah ↗