How did Hashem profane "Sarei Kodesh"?
Eichah Rabah (2:5): Yisrael knew the names of angels, and forced them to do things. They expected to be able to defend themselves via this. Hashem changed the angels' names to thwart them.
Rashi: It was due to your sins.
Radak: The Vov does not change the verb to past tense. (If it did, there would be a Kamatz under the Vov; rather, it has a Pasach.) In every generation I profane Sarei Kodesh, and I give Yakov to Cherem and Yisrael to reviling, in your sins. I do not totally eradicate them. The Sarei Kodesh are profaned in the hand of the enemy due to the sin of the Sarim who sin. The good perish due to the many evil - "Pen Tisafeh ba'Avon ha'Ir" (Bereishis 19:15). An individual is saved amidst a Rabim only via a miracle. "Nasenu Es Nivlas Avadecha Ma'achal l'Of ha'Shamayim Besaer Chasidecha l'Chayso Aretz" (Tehilim 79:2). Hashem's servants and Chasidim perished due to the sin of the Rabim.
Radak citing a Midrash: Sarei Kodesh are the Leviyim.
Malbim: Sarei Kodesh are the advocates (Kohanim and Nevi'im - 27); since they sinned, I profaned them.
What is the meaning of "la'Cherem"?
Rashi: It is to be killed, like "v'Es Kol ha'Neshamah Hecherim" (Yehoshua 10:40). Malbim - this was because "your first father sinned" (27).
What is "l'Gidufim"?
Radak: The Nochrim disgrace and revile them [Malbim - due to their Torah and Kedushah].