Development of a nanobody-based immunoassay for the sensitive detection of fibrinogen-like protein 1.

Immune checkpoint inhibition is an important strategy in cancer therapy. Blockade of CTLA-4 and PD-1/PD-L1 is well developed in clinical practice. In the last few years, LAG-3 has received much interest as an emerging novel target in immunotherapy. It was recently reported that FGL1 is a major ligand of LAG-3, which is normally secreted by the liver but is upregulated in several human cancers. FGL1 is a crucial biomarker and target for cancer immunotherapy. As the efficacy of immunotherapy is limited to specific types of patients, the subset of patients needs to be selected appropriately to receive precise treatment according to different biomarkers. To date, there is no test to accurately assess FGL1 expression levels. Nanobodies have some outstanding features, such as high stability, solubility and affinity for diagnostic and therapeutic applications. Here, we report the development and validation of a rapid, sensitive, and cost-effective nanobody-based immunoassay for the detection of FGL1 in human serum. In this study, human FGL1 recombinant protein was expressed and purified for the first time as an immunized antigen. Then, we constructed a nanobody phage display library and screened several nanobodies that bind FGL1 with high affinity. We selected two nanobodies targeting different epitopes of FGL1, one as a capture and the other conjugated with HRP as a probe. The double nanobody-based sandwich ELISA to detect the concentration of FGL1 showed a good response relationship in the range of 15.625-2000 ng/mL, and the recoveries from the spiked sample were in the range of 78% and 100%. This assay could be used as a potential approach for evaluating FGL1 expression for patient stratification and for predicting the therapeutic efficacy of targeting the LAG3/FGL1 axis.

Anatomy of the retrohepatic tunnel in a Chinese population and its clinical application in liver surgery.

Liver hanging maneuver (LHM) is an important technique in liver surgery. However, applied anatomy of the retrohepatic tunnel for the surgical approach in Chinese population needs further study. In this study, to explore the basic anatomy of retrohepatic tunnel and its clinical application in a Chinese population, a total of 32 formalin-fixed cadavers were dissected, related parameters were measured, and their clinical applications were discussed. The length of the retrohepatic tunnel was (60.6 ± 9.9) mm. The width of the retrohepatic tunnel superior opening was (13.8 ± 3.9) mm. The width of the retrohepatic tunnel inferior opening was (15.2 ± 7.4) mm. The hepatic short vessels were distributed along the middle and lower 1/3 of hepatic inferior vena cava (HIVC), with a slight predominance on its left wall. A few hepatic short vessels were distributed along the upper 1/3 of the HIVC. We concluded: the anatomy of the retrohepatic tunnel provides a basis for use of LHM in liver surgery; more hepatic short vessels from hepatic caudate lobe can be preserved via right approach. The retrohepatic tunnel can be used as a good surgical approach in liver surgery; its application also has important significance in laparoscopic minimally invasive liver surgery.