Membrane-bound programmed cell death-1 (mPD-1) and membrane-bound programmed cell death-ligands (mPD-Ls) have soluble forms, which are soluble programmed cell death-1 (sPD-1) and soluble programmed cell death-ligands (sPD-Ls) [including soluble programmed cell death-ligand 1 (sPD-L1) and soluble programmed cell death-ligand 2 (sPD-L2)]. sPD-1 and sPD-L2 are mainly produced by alternative splicing isoforms of PD-1 mRNA, while sPD-L1 is produced by matrix metalloproteinases (MMPs) cutting membrane-bound programmed cell death-ligand 1 (mPD-L1). sPD-1 and sPD-Ls play an important role in autoimmune regulation via blocking the mPD-1 /mPD-L1 pathway, while connective tissue disease (CTD) is a kind of disease caused by autoimmune reaction, and abnormal function of mPD-1/mPD-L1 can occur in the occurrence and development of many autoimmune diseases. Therefore, sPD-1 and sPD-Ls play an important role in the pathogenesis of CTD caused by autoimmune reaction via blocking the mPD-1 /mPD-L1 pathway. It is of great practical significance to understand clinical value of sPD-1 and sPD-Ls in various CTDs for improving the quality of life of patients and the underlying mechanism.
膜结合型程序性死亡受体1(membrane-bound programmed cell death-1，mPD-1)及膜结合型程序性死亡受体配体(membrane-bound programmed cell death-ligands，mPD-Ls)存在可溶性形式，分别为可溶性程序性死亡受体1(soluble programmed cell death-1，sPD-1)和可溶性程序性死亡受体配体(soluble programmed cell death-ligands，sPD-Ls)[包括可溶性程序性死亡受体配体1(soluble programmed cell death-ligand 1，sPD-L1)和可溶性程序性死亡受体配体2(soluble programmed cell death-ligand 2，sPD-L2)]。sPD-1和sPD-L2主要由PD-1 mRNA的选择性剪接异构体翻译产生，而sPD-L1则是由基质金属蛋白酶(matrix metalloproteinases，MMPs)剪切膜结合型程序性死亡受体配体1(membrane-bound programmed cell death-ligand 1，mPD-L1)产生。sPD-1和sPD-Ls通过阻断mPD-1/mPD-L1通路在自身免疫调节中起重要作用，而结缔组织病(connective tissue disease，CTD)是由自身免疫反应等引起的一类疾病，并且多种自身免疫性疾病在发生、发展过程中均可出现mPD-1/mPD-L1的功能异常。故sPD-1和sPD-Ls通过阻断mPD-1/mPD-L1通路，在由自身免疫反应引起的CTD发病机制中起重要作用。了解sPD-1和sPD-Ls在CTD中的作用机制和临床价值对改善患者的生活质量具有重要的现实意义。.
Keywords: connective tissue disease; pathogenesis; soluble programmed cell death-1; soluble programmed cell death-ligands.