Re-evalution of the measurement of haptoglobin in human plasma samples

Haptoglobin (Hp) is an abundant plasma protein scavenging hemoglobin (Hb) via CD163 on macrophages. This process consumes Hp, which therefore negatively correlates to hemolysis. However, exact measurements of Hp plasma levels are complicated by different phenotypes (Hp1-1, Hp2-1, and Hp2-2) forming different oligomeric states with differences in immunoreactivity. In addition, humans have an immune-cross-reactive Hp-related protein. In the present study, we developed Hp-specific monoclonal antibodies for an accurate Hp analysis of the different Hp phenotypes in a panel of 112 anonymous samples from hospitalized individuals subjected to routine Hp immunoturbidimetric measurements. The data revealed immunoturbidimetry as a reliable method in most cases but also that the use of non-phenotype-specific calibrators leads to substantial bias in the measurement of the Hp-concentration, non at least in Hp1-1 individuals. Furthermore, analysis of the Hb-dependence of the CD163 interaction with Hp1-1 and Hp2-2 showed that a higher 'cost-effectiveness' in the consumption of dimeric Hp1-1 versus multimeric Hp phenotypes is a likely contribution to the observed differences in the plasma levels of the Hp phenotypes. In conclusion, the determination of Hp phenotype and the use of phenotype-specific calibrators are essential to obtain a precise estimate of the Hp level in healthy and diseased individuals.

Bilirubin in metabolic syndrome and associated inflammatory diseases: New perspectives

Diabetes mellitus is one of the major global health issues, which is closely related to metabolic dysfunction and the chronic inflammatory diseases. Multiple studies have demonstrated that serum bilirubin is negatively correlated with metabolic syndrome and associated inflammatory diseases, including atherosclerosis, hypertension, etc. However, the roles of bilirubin in metabolic syndrome and associated inflammatory diseases still remain unclear. Here, we explain the role of bilirubin in metabolic syndrome and chronic inflammatory diseases and its therapeutic potential. Understanding the role of bilirubin activities in diabetes may serve as a therapeutic target for the treatment of chronic inflammatory diseases in diabetic patients.