Protection of the endothelium is provided by circulating sphingosine-1-phosphate (S1P), which maintains vascular integrity. We show that HDL-associated S1P is bound specifically to both human and murine apolipoprotein M (apoM). Thus, isolated human ApoM + HDL contained S1P, whereas ApoM − HDL did not. Moreover, HDL in Apom −/− mice contains no S1P, whereas HDL in transgenic mice overexpressing human apoM has an increased S1P content. The 1.7-Å structure of the S1P-human apoM complex reveals that S1P interacts specifically with an amphiphilic pocket in the lipocalin fold of apoM. Human ApoM + HDL induced S1P 1 receptor internalization, downstream MAPK and Akt activation, endothelial cell migration, and formation of endothelial adherens junctions, whereas apoM − HDL did not. Importantly, lack of S1P in the HDL fraction of Apom −/− mice decreased basal endothelial barrier function in lung tissue. Our results demonstrate that apoM, by delivering S1P to the S1P 1 receptor on endothelial cells, is a vasculoprotective constituent of HDL.endothelial function | crystal structure | sphingolipids | vascular permeability | atherosclerosis S phingosine-1-phosphate (S1P), the phosphorylated metabolite of D-sphingosine, binds to five G protein-coupled receptors (S1P 1 -S1P 5 ) and regulates a plethora of biological actions (1-6). In particular, the prototypical S1P 1 receptor is essential for vascular maturation during development and promotes endothelial cell migration, angiogenesis, and barrier functions (7-9). Thus, S1P is required for maintenance of the barrier property of the lung endothelium (10). Plasma S1P, which is derived from several cellular sources (11,12), is associated with HDL (∼65%) and albumin (∼35%) (3, 5). HDLinduced vasorelaxation as well as barrier-promoting and prosurvival actions on the endothelium have been attributed to S1P signaling (2, 4, 13). Hence, much of the endothelium-protective actions of HDL may result from the actions of S1P on the endothelial S1P receptors. However, the molecular nature of the S1P binding to HDL and interaction with S1P receptors has not been characterized.Apolipoprotein M (apoM) is a lipocalin that resides mainly in the plasma HDL fraction (14). The retained hydrophobic NH 2 -terminal signal peptide anchors apoM in the phospholipid layer of the lipoprotein and prevents filtration of the ∼22-kDa protein in the kidney (15). The biological functions of apoM are understood only partly. Studies in apoM gene-modified mice suggest that apoM has antiatherogenic effects, possibly related in part to apoM's ability to increase cholesterol efflux from macrophage foam cells, to increased preβ-HDL formation, and to antioxidative effects (16)(17)(18). The recent elucidation of the crystal structure of human recombinant apoM (r-apoM) demonstrated a typical lipocalin fold characterized by an eightstranded antiparallel β-barrel enclosing an internal binding pocket that probably facilitates binding of small lipophilic ligands (19).Indeed, r-apoM expressed in Escherichia coli was found to co...

IntroductionApolipoprotein M (apoM) is present in 5% of high-density lipoprotein (HDL) particles in plasma. It is a carrier of sphingosine-1-phosphate (S1P), which is important for vascular barrier protection. The aim was to determine the plasma concentrations of apoM during sepsis and systemic inflammatory response syndrome (SIRS) and correlate them to levels of apolipoprotein A-I (apoA1), apolipoprotein B (apoB), HDL-, and low-density lipoprotein (LDL)-cholesterol.MethodsPlasma samples from patients with (1), severe sepsis with shock (n = 26); (2), severe sepsis without shock (n = 44); (3), sepsis (n = 100); (4), infections without SIRS (n = 43); and (5) SIRS without infection (n = 20) were analyzed. The concentrations of apoM, apoA1, and apoB were measured with enzyme-linked immunosorbent assays (ELISAs). Total, HDL-, and LDL-cholesterol concentrations were measured with a commercial HDL/LDL cholesterol test.ResultsApoM concentrations correlated negatively to acute-phase markers. Thus, apoM behaved as a negative acute-phase protein. Decreased values were observed in all patient groups (P < 0.0001), with the most drastic decreases observed in the severely sick patients. ApoM levels correlated strongly to those of apoA1, apoB, HDL, and LDL cholesterol. The HDL and LDL cholesterol levels were low in all patient groups, as compared with controls (P < 0.0001), in particular, HDL cholesterol. ApoA1 and apoB concentrations were low only in the more severely affected patients.ConclusionsDuring sepsis and SIRS, the plasma concentrations of apoM decrease dramatically, the degree of decrease reflecting the severity of the disease. As a carrier for barrier-protective S1P in HDL, the decrease in apoM could contribute to the increased vascular leakage observed in sepsis and SIRS.

Background Apolipoprotein M (apoM) is a 25-kDa apolipoprotein present in 5% of high-density lipoprotein (HDL) particles. It is suggested to be anti-atherogenic and to play a key role in sustaining endothelial barrier integrity. SLE patients have increased cardiovascular disease risk, and we aimed to investigate if apoM levels reflect endothelial function in SLE. Since apoM plasma levels decrease during inflammatory conditions, our aim was also to determine the impact of SLE disease activity on apoM plasma levels. Methods Plasma concentrations of apoM were measured by ELISA in two patient groups with systemic lupus erythematosus (SLE) and in 79 healthy control individuals. In patient group I ( n = 84), evaluation time points were selected with the objective to include a wide range of clinical and laboratory variables reflecting disease activity which was measured as SLEDAI. In patient group II consisting of 140 consecutive patients, endothelial function was measured by a finger plethysmograph. A low Reactive Hyperemia Index (RHI) value indicates endothelial dysfunction. Results SLE patients had decreased levels of apoM compared to healthy controls ( p < 0.01), with apoM levels correlating inversely with SLEDAI ( r = − 0.31, p < 0.01) as well as with levels of CRP ( r = − 0.26, p = 0.02) and positively with levels of C3 ( r = 0.29, p < 0.01). ApoM levels were particularly low in patients with active disease from the kidney and skin and in patients with leukopenia or positive anti-dsDNA antibody test ( p < 0.05). ApoM levels correlated with RHI values in young SLE patients ( r = 0.32, p = 0.01), consistent with the important role of apoM in regulating endothelial integrity. Conclusions ApoM levels may be regulated by SLE-related inflammatory processes and could be a marker of disease activity and endothelial dysfunction, in particular in young SLE patients. Further studies are needed to investigate the predictive value of apoM in the development of a cardiovascular disease. Electronic supplementary material The online version of this article (10.1186/s13075-019-1890-2) contains supplementary material, which is available to authorized users.

ObjectiveManagement and diagnosis of multiple human cancers remains a challenge and search for a common biomarker is still debatable. In this manuscript we have evaluated the use of monoclonal antibody UNIVmAb, to detect the protein (H11) as a common biomarker for all cancers irrespective of the grade and origin. We have shown by both ELISA and Western Blot that the H11 protein, is a unique hyaluronan binding protein that has not been detected earlier. H11 protein was fractionated in an anion exchange column followed by cibacron blue gel exclusion chromatography. Hyaluronan binding H11 protein reacted with Monoclonal antibody UNIVmAb and b-HA inspite of b-Hyaluronan (biotinylated Hyaluronan) interaction and HA-Oligo (Hyaluronan oligosaccharides) competition from various grades of Human cancers sera.ResultsELISA, Western blot and b-Hyaluronan interactions clearly showed an over-expression of UNIVmAb reacted H11 protein in all fifty cancer’s sera when compared with seventy normal sera. UNIVmAb reactive H11 protein can be used as a common biomarker. We believe, UNIVmAb detected H11 protein, is a unique hyaluronan binding protein, that can be used as a common biomarker for all cancers.

Colorectal cancer (CRC) is the third most common cancer; cancer biomarker discovery is important for disease detection and management. It is known that hyaluronic acid and its receptors are ubiquitously expressed in almost all human tissues. Earlier we have shown that a monoclonal antibody H11B2C2, presently known as UNIVmAb, reactive hyaladherin expressed in multiple human cancers mainly using immunohistochemistry. However, the nature of the antigen and its sequence homology are not known. In the current study, a comprehensive investigation was performed to explore the nature of the antigen and its homology using both biochemical and proteomic analysis. Our results showed that UNIVmAb reactive 57 kDa antigen was overexpressed in advanced grade colorectal cancer tissues compared to benign and its adjacent benign tissues. Biochemical investigations including biotinylated hyaluronic acid-pulldown, Immunoprecipitation, HA-oligo competition experiments confirmed that the UNIVmAb reactive 57 kDa antigen is a member of hyaladherin. Further Proteomic analysis showed that the antigen has homology with IGHG1 (Igγ-1 chain C region), IGg superfamily, and is associated with human serum albumin.

Objective: Management and diagnosis of multiple human cancers remain a challenge and search for a common biomarker are still debatable. We described a method and evaluated the use of monoclonal antibody UNIVMab, to detect the protein (H11) as a common biomarker for all cancer irrespective of grade and origin . H11 protein identified as a unique Hyaluronan binding protein not detected earlier. We applied this test both with ELISA, Western blot, fractionated in anion exchange, cibacron gel exclusion, b-Hyaluronan interaction and HA-Oligo competition from various grades of Human cancers sera and processed for the detection of hyaluronan binding protein H11, reacted with Monoclonal antibody UNIVMab and with b-HA. Results: Studies from ELISA, Western blot and b-Hyaluronan interactions showed a definitive positive over-expression of UNIVMab reacted H11 antigen in all fortyfive cancer sera compared to normal sera and can be used as a common biomarker. We believe, UNIVMab detected H11 antigen, a unique hyaluronan binding protein, is a common biomarker for all cancer sera. Keywords: ELISA, Western blot, Hyaluronic acid binding protein, H11 (sera antigen), UNIVMab. Common Biomarker, Cancers Sera

Objective: Management and diagnosis of multiple human cancers remain a challenge and search for a common biomarker are still debatable. We described a method and evaluated the use of monoclonal antibody UNIVMab, to detect the protein (H11) as a common biomarker for all cancer irrespective of grade and origin . H11 protein identified as a unique Hyaluronan binding protein not detected earlier. We applied this test both with ELISA, Western blot, fractionated in anion exchange, cibacron gel exclusion, b-Hyaluronan interaction and HA-Oligo competition from various grades of Human cancers sera and processed for the detection of hyaluronan binding protein H11, reacted with Monoclonal antibody UNIVMab and with b-HA. Results: Studies from ELISA, Western blot and b-Hyaluronan interactions showed a definitive positive over-expression of UNIVMab reacted H11 antigen in all fortyfive cancer sera compared to normal sera and can be used as a common biomarker. We believe, UNIVMab detected H11 antigen, a unique hyaluronan binding protein, is a common biomarker for all cancer sera. Keywords: ELISA, Western blot, Hyaluronic acid binding protein, H11 (sera antigen), UNIVMab. Common Biomarker, Cancers Sera

Objective: Management and diagnosis of multiple human cancers remain a challenge and search for a common biomarker are still debatable. We described a method and evaluated the use of monoclonal antibody UNIVMab, to detect the protein (H11) as a common biomarker for all cancer irrespective of grade and origin . H11 protein identified as a unique Hyaluronan binding protein not detected earlier. We applied this test both with ELISA, Western blot, fractionated in anion exchange, cibacron gel exclusion, b-Hyaluronan interaction and HA-Oligo competition from various grades of Human cancers sera and processed for the detection of hyaluronan binding protein H11, reacted with Monoclonal antibody UNIVMab and with b-HA. Results: Studies from ELISA, Western blot and b-Hyaluronan interactions showed a definitive positive over-expression of UNIVMab reacted H11 antigen in all fortyfive cancer sera compared to normal sera and can be used as a common biomarker. We believe, UNIVMab detected H11 antigen, a unique hyaluronan binding protein, is a common biomarker for all cancer sera. Keywords: ELISA, Western blot, Hyaluronic acid binding protein, H11 (sera antigen), UNIVMab. Common Biomarker, Cancers Sera