Supreme is tightening its global grip. The skate brand that spawned hordes of imitators and copycats as it staked out its own edgy-cool corner of the luxury world has secured its trademark in China. The impact appears to have been immediate. The Chinese Trademark Office officially gave the nod to the mark on Jan. 21, according to public documents. That seems to have led quickly to at least some enforcement actions in the country, including the shuttering of the widely publicized Supreme shop in Shanghai that was set up by another company, as detailed in local media.