The objectives of the present study aimed to confirm ADAMTSL4 levels in the proteomics between healthy control population and patients with IPAH，to analyze the expression levels of ADAMTSL4 between patients with IPAH and CTEPH, and to investigate whether serum levels of ADAMTSL4 might be used as biomarkers of disease severity in these patient populations.
ADAMTSL4 (A disintegrin and metalloproteinase with thrombospondin motifs like) is a member of the ADAMTSL family. ADAMTSL4 is one of the family of 7 ADAMTS-Like proteins, themselves part of the Thrombospondin type 1 repeat (TSR) superfamily of proteins. These 7 proteins are divided into two distinct clades, of which ADAMTSL4 and ADAMTS-Like 6 form part of one clade, differing from ADAMTS-Like 1, ADAMTS-Like 3 and ADAMTS-Like 7 by lacking immunoglobulin repeat regions. ADAMTSL4 is widely expressed in brain, colon, heart, kidney, liver, lung, pancreas and spleen, yet, its precise role is unclear. in addition, ADAMTSL4 protein high expression to the medial layer of the arterial wall, and medial vascular smooth muscle cells specifically.