Serum samples were stored at – 80 °C within 4 h of sampling until use. Serum levels of 180 unique inflammation and immune response–related proteins (supplementary Table S1 ) were measured using proximity extension immunoassay (PEA; Olink Proteomics, Uppsala, Sweden) [22 (link)], using the ProSeek Multiplex Inflammation and Immune Response kits.
Briefly, the proximity extension immunoassay technology is based on dual recognition of serum proteins by pairs of antibodies coupled to a cDNA-strand that ligates when brought into proximity by its target. This DNA tag is PCR amplified and detected using a Biomark HD 96 × 96 dynamic PCR array (Fluidigm, San Francisco, USA). After corrections from DNA extension- and interpolation controls, a normalized protein expression value (NPX) is generated on a log-2 scale.
Briefly, the proximity extension immunoassay technology is based on dual recognition of serum proteins by pairs of antibodies coupled to a cDNA-strand that ligates when brought into proximity by its target. This DNA tag is PCR amplified and detected using a Biomark HD 96 × 96 dynamic PCR array (Fluidigm, San Francisco, USA). After corrections from DNA extension- and interpolation controls, a normalized protein expression value (NPX) is generated on a log-2 scale.