Binding and carrying role of human serum albumin from various sources to sphingosine-1-phosphate / 中国输血杂志

ABSTRACT

【Objective】 To investigate the binding and carrying effects of human serum albumin (HSA) from various sources on sphingosine-1-phosphate (S1P). 【Methods】 Utilizing human plasma-derived HSA (pHSA) and recombinant HSA (rHSA) samples as the focal points of our investigation, LC-MS/MS technology was employed to meticulously compare and analyze the disparities in S1P content among the aforementioned samples. Subsequently, under physiological concentration conditions, S1P was directly introduced to HSA samples for loading processing, facilitating a comprehensive comparison of the binding efficacy of HSA from different sources to S1P. Within a serum-free culture setting, HSA samples from various sources were co-cultured with HUVEC cells. The alterations in S1P content within the cell culture supernatant across different treatment groups were meticulously analyzed, allowing for a nuanced comparison of the S1P carry effects exerted by HSA from different sources on cells.The interaction between HSA and S1P molecules from different sources was analyzed and their affinity was calculated using surface plasmon resonance (SPR) technology. Furthermore, leveraging AutoDock Vina software and the Molprophet platform, the molecular docking analysis of HSA and S1P was conducted, aiming to predict the key binding pocket domain of S1P within HSA. 【Results】 All pHSA samples exhibited detectable levels of S1P (ranging from 3.31±0.03 to 30.35±0.07 μg/L), with significant variations observed among pHSA samples from different manufacturers (P<0.001). Conversely, S1P was undetectable in all rHSA samples. Upon load treatment, the binding affinity of HSA from diverse sources to S1P demonstrated significant discrepancies (P<0.001), with rHSA exhibiting approximately double the average S1P loading compared to pHSA (ΔCrHSA=801.75±142.45 μg/L vs ΔCpHSA=461.94±85.73 μg/L; P<0.001, t=5.006). Co-culture treatment outcomes revealed a significant elevation in S1P concentration within the supernatant after 6 hours of co-culture across all HSA sample processing groups with HUVEC cells, while no changes were observed in the supernatant of the blank control group. Notably, significant differences in supernatant S1P concentration were observed among treatment groups at 6 h, 12 h, and 24 h (P<0.001). SPR analysis unveiled a stronger affinity of pHSA for S1P compared to rHSA (KDpHSA-S1P: 2.38E-06, KDrHSA-S1P: 3.72E-06). Molecular docking analysis and binding pocket prediction suggested that the key binding pocket of HSA and S1P may reside in the IB subdomain of the HSA molecule. 【Conclusion】 HSA from various sources exhibits distinct binding and carrying effects on S1P, which appear to be closely associated with the IB subdomain of the HSA molecule.