The upscale community was completely isolated from the poverty-stricken areas around it.

isolated 是动词 isolate 的过去分词形式，在句中表示被动状态。isolate 由词根 isola（源自拉丁语"岛屿"）和动词后缀 -ate 组成，字面意思是"使成为孤岛"，引申为"隔离、隔绝"的意思。这里表示"被隔离开来"的状态。