Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:[22] reported that proinflammatory cytokines, including TNFa, IL-8 and IL-1bwere up-regulated in the monocyte-derived macrophages (MDM) from low-HDL subjects.
Category: