Effect of vitamin D3 supplementation on blood parameters and liver gene expression in female rats.

BACKGROUND: To better understand the molecular mechanism responsible for the therapeutic potential of vitamin D, we conducted an analysis of the liver transcriptomes of adult female rats. METHODS: Adult female rats (n = 18) were divided into three groups, receiving different doses of vitamin D: group I, 0; group II, 1000 U/kg; and group III, 5000 U/kg. Growth, body weight, the weight of main organs, blood haematological and biochemical parameters were evaluated. Gene expression in the liver were analyzed using RNA-seq and qPCR techniques. RESULTS: We observed a lower platelet count (p < 0,008) and a significantly greater (p < 0.02) number of WBCs in rats supplemented with 1000 U/kg than in rats from group III (5000 U/kg). Moreover, we noted a trend (p < 0.06) in total cholesterol concentration, suggesting a linear decrease with increasing doses of vitamin D. RNA-seq analysis did not reveal any differentially expressed genes with FDR < 0.05. However, GSEA revealed significant activation of a number of processes and pathways, including: "metallothionein, and TspO/MBR family", and "negative regulation of tumor necrosis factor production". qPCR analysis revealed significant upregulation of the Mt1, Mt2 and Orm1 genes in animals receiving high doses of vitamin D (p < 0.025, p < 0.025, and p < 0009, respectively). Moreover, Srebp2 and Insig2 were significantly lower in both experimental groups than in the control group (p < 0.003 and p < 0.036, respectively). CONCLUSIONS: Our results support the anti-inflammatory, anitioxidant and anticholesterologenic potential of vitamin D but suggest that high doses of vitamin D are needed to obtain significant results in this regard.

Alpha 1-acid glycoprotein is upregulated in severe COVID-19 patients and decreases neutrophil NETs in SARS-CoV-2 infection.

Orosomucoid, or alpha-1 acid glycoprotein (AGP), is a major acute-phase protein expressed in response to systemic injury and inflammation. AGP has been described as an inhibitor of neutrophil migration on sepsis, particularly its immunomodulation effects. AGP's biological functions in coronavirus disease 2019 (COVID-19) are not understood. We sought to investigate the role of AGP in severe COVID-19 infection patients and neutrophils infected with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Epidemiological data, AGP levels, and other laboratory parameters were measured in blood samples from 56 subjects hospitalized in the ICU with SARS-CoV-2 infection. To evaluate the role of AGP in NETosis in neutrophils, blood samples from health patients were collected, and neutrophils were separated and infected with SARS-CoV-2. Those neutrophils were treated with AGP or vehicle, and NETosis was analyzed by flow cytometry. AGP was upregulated in severe COVID-19 patients (p<0.05). AGP level was positively correlated with IL-6 and C-reactive protein (respectively, p=0.005, p=0.002) and negatively correlated with lactate (p=0.004). AGP treatment downregulated early and late NETosis (respectively, 35.7% and 43.5%) in neutrophils infected with SARS-CoV-2 and up-regulated IL-6 supernatant culture expression (p<0.0001). Our data showed increased AGP in COVID-19 infection and contributed to NETosis regulation and increased IL-6 production, possibly related to the Cytokine storm in COVID-19.

The Hepatokine Orosomucoid 2 Mediates Beneficial Metabolic Effects of Bile Acids.

Bile acids (BAs) are pleiotropic regulators of metabolism. Elevated levels of hepatic and circulating BAs improve energy metabolism in peripheral organs, but the precise mechanisms underlying the metabolic benefits and harm still need to be fully understood. In the current study, we identified orosomucoid 2 (ORM2) as a liver-secreted hormone (i.e., hepatokine) induced by BAs and investigated its role in BA-induced metabolic improvements in mouse models of diet-induced obesity. Contrary to our expectation, under a high-fat diet (HFD), our Orm2 knockout (Orm2-KO) exhibited a lean phenotype compared with C57BL/6J control, partly due to the increased energy expenditure. However, when challenged with a HFD supplemented with cholic acid, Orm2-KO eliminated the antiobesity effect of BAs, indicating that ORM2 governs BA-induced metabolic improvements. Moreover, hepatic ORM2 overexpression partially replicated BA effects by enhancing insulin sensitivity. Mechanistically, ORM2 suppressed interferon-γ/STAT1 activities in inguinal white adipose tissue depots, forming the basis for anti-inflammatory effects of BAs and improving glucose homeostasis. In conclusion, our study provides new insights into the molecular mechanisms of BA-induced liver-adipose cross talk through ORM2 induction.

Quorum sensing-associated bacterial phenazines are potential ligands of human α1 -acid glycoprotein.

α1 -Acid glycoprotein (AGP) is a prominent acute phase component of blood plasma and extravascular fluids. As a member of the immunocalins, AGP exerts protective effects against Gram-negative bacterial infections but the underlying molecular mechanisms still need to be elucidated. Notably, the chemical structures of phenothiazine, phenoxazine and acridine type ligands of AGP are similar to those of phenazine compounds excreted by the opportunistic human pathogen Pseudomonas aeruginosa and related bacterial species. These molecules, like pyocyanin, act as quorum sensing-associated virulence factors and are important contributors to bacterial biofilm formation and host colonisation. Molecular docking simulations revealed that these agents fit into the multi-lobed cavity of AGP. The binding site is decorated by several aromatic residues which seem to be essential for molecular recognition of the ligands allowing multifold π-π and CH-π interactions. The estimated affinity constants (~105 M-1 ) predict that these secondary metabolites could be trapped inside the ß-barrel of AGP which in turn could reduce their cytotoxic effects and disrupt the microbial QS network, facilitating the eradication of bacterial infections.

Interactions of fentanyl with blood platelets and plasma proteins: platelet sensitivity to prasugrel metabolite is not affected by fentanyl under in vitro conditions.

BACKGROUND: Clinical trials indicate that fentanyl, like morphine, may impair intestinal absorption and thus decrease the efficacy of oral P2Y12 inhibitors, such as clopidogrel, ticagrelor, and prasugrel. However, the ability of fentanyl to directly negate or reduce the inhibitory effect of P2Y12 receptor antagonists on platelet function has not been established. A series of in vitro experiments was performed to investigate the ability of fentanyl to activate platelets, potentiate platelet response to ADP, and/or diminish platelet sensitivity to prasugrel metabolite (R-138727) in agonist-stimulated platelets. The selectivity and specificity of fentanyl toward major carrier proteins has been also studied. METHODS: Blood was obtained from healthy volunteers (19 women and 12 men; mean age 40 ± 13 years). Platelet function was measured in whole blood, platelet-rich plasma and in suspensions of isolated platelets by flow cytometry, impedance and optical aggregometry. Surface plasmon resonance and molecular docking were employed to determine the binding kinetics of fentanyl to human albumin, α1-acid glycoprotein, apolipoprotein A-1 and apolipoprotein B-100. RESULTS: When applied at therapeutic and supratherapeutic concentrations under various experimental conditions, fentanyl had no potential to stimulate platelet activation and aggregation, or potentiate platelet response to ADP, nor did it affect platelet susceptibility to prasugrel metabolite in ADP-stimulated platelets. In addition, fentanyl was found to interact with all the examined carrier proteins with dissociation constants in the order of 10-4 to 10-9 M. CONCLUSIONS: It does not seem that the delayed platelet responsiveness to oral P2Y12 inhibitors, such as prasugrel, in patients undergoing percutaneous coronary intervention, results from direct interactions between fentanyl and blood platelets. Apolipoproteins, similarly to albumin and α1-acid glycoprotein, appear to be important carriers of fentanyl in blood.

The adipokine orosomucoid alleviates adipose tissue fibrosis via the AMPK pathway.

The excess deposition of underlying extracellular matrix (ECM) in adipose tissue is defined as adipose tissue fibrosis that is a major contributor to metabolic disorder such as obesity and type 2 diabetes. Anti-fibrosis therapy has received much attention in the treatment of metabolic disorders. Orosomucoid (ORM) is an acute-phase protein mainly produced by liver, which is also an adipokine. In this study, we investigated the effects of ORM on adipose tissue fibrosis and the potential mechanisms. We showed that ORM1-deficient mice exhibited an obese phenotype, manifested by excessive collagen deposition in adipose tissues and elevated expression of ECM regulators such as metalloproteinases (MMP-2, MMP-13, MMP-14) and tissue inhibitors of metalloproteinases (TIMP-1, TIMP-2, TIMP-3). Administration of exogenous ORM (50 mg· kg-1· d-1, ip) for 7 consecutive days in high-fat diet (HFD)-fed mice and leptin receptor (LepR)-deficient db/db mice attenuated these abnormal expressions. Meanwhile, ORM administration stimulated AMP-activated protein kinase (AMPK) phosphorylation and decreased transforming growth factor-ß1 (TGF-ß1) level in adipose tissues of the mice. In TGF-ß1-treated 3T3-L1 fibroblasts, ORM (10 µg/mL) improved the impaired expression profiles of fibrosis-related genes, whereas a selective AMPK inhibitor dorsomorphin (1 µmol/mL) abolished these effects. Together, our results suggest that ORM exerts a direct anti-fibrosis effect in adipose tissue via AMPK activation. ORM is expected to become a novel target for the treatment of adipose tissue fibrosis.

Hemoglobin stimulates vigorous growth of Streptococcus pneumoniae and shapes the pathogen's global transcriptome.

Streptococcus pneumoniae (Spn) must acquire iron from the host to establish infection. We examined the impact of hemoglobin, the largest iron reservoir in the body, on pneumococcal physiology. Supplementation with hemoglobin allowed Spn to resume growth in an iron-deplete medium. Pneumococcal growth with hemoglobin was unusually robust, exhibiting a prolonged logarithmic growth, higher biomass, and extended viability in both iron-deplete and standard medium. We observed the hemoglobin-dependent response in multiple serotypes, but not with other host proteins, free iron, or heme. Remarkably, hemoglobin induced a sizable transcriptome remodeling, effecting virulence and metabolism in particular genes facilitating host glycoconjugates use. Accordingly, Spn was more adapted to grow on the human α - 1 acid glycoprotein as a sugar source with hemoglobin. A mutant in the hemoglobin/heme-binding protein Spbhp-37 was impaired for growth on heme and hemoglobin iron. The mutant exhibited reduced growth and iron content when grown in THYB and hemoglobin. In summary, the data show that hemoglobin is highly beneficial for Spn cultivation in vitro and suggest that hemoglobin might drive the pathogen adaptation in vivo. The hemoglobin receptor, Spbhp-37, plays a role in mediating the positive influence of hemoglobin. These novel findings provide intriguing insights into pneumococcal interactions with its obligate human host.

Effects of central and peripheral administration of an acute-phase protein, α-1-acid-glycoprotein, on feed intake and rectal temperature in sheep.

In rodents, an acute-phase protein, α-1-acid-glycoprotein (AGP), was shown to provide a link between inflammation and suppression of feed intake by acting as a leptin receptor agonist. The objective of this study was to determine the effects of AGP on feed intake and rectal temperature in sheep. Ewes were ovariectomized, implanted with a cannula into a lateral ventricle of the brain, and kept indoors in individual pens. Feed intake and rectal temperature were determined for sheep in all experiments. In the first experiment, ewes (n = 4) received 1 of 4 treatments [0 (control), 0.012 (low), 0.06 (medium), or 0.30 (high) mg/kg BW AGP] into the lateral ventricle (ICV). All sheep received all treatments in a Latin square design balanced for carryover effects with 10 d between treatments. In the second experiment, ewes (n = 10) received 1 of 2 treatments (0 and 3 mg/kg BW of AGP) intravenously (IV) in a completely randomized design. In the third experiment, ewes (n = 19) received peripheral treatments (IV) of an antipyretic [0 (control) or 2.2 mg/kg BW flunixin meglumine (FLU)] 30 min before receiving central AGP [0 (control) or 0.3 mg/kg BW of AGP] in a completely randomized design. All data were analyzed using a mixed model analysis of variance and tested for effects of treatment, time, and the interaction of treatment and time. Cumulative 48-h feed intake after administration of treatments was also determined. In the first experiment, there was no effect of ICV treatment (P = 0.37) on feed intake rate or on cumulative feed intake (P = 0.31). There was an effect of ICV treatment (P = 0.002) on rectal temperatures, which were greater (P < 0.05) after the high dose of centrally administered AGP. In the second experiment, there was no effect of AGP administration IV on feed intake rate (P = 0.98), on cumulative feed intake (P = 0.41) or on rectal temperature (P = 0.71). In the third experiment, there was an effect of central AGP treatment (P < 0.0001) and an interaction of central AGP and time (P < 0.0001) on rectal temperature, whereas FLU had no effect (P = 0.93), demonstrating that AGP increased rectal temperatures regardless of antipyretic treatment. These results indicate that central AGP increases rectal temperature in sheep by pathways that do not involve prostaglandins. Further research is needed to determine whether AGP may be an important integrator of energy balance and inflammation.

α-1 acid glycoprotein inhibits insulin responses by glucose oxidation, protein synthesis and protein breakdown in mouse C2C12 myotubes.

Increased plasma α-1 acid glycoprotein (AGP) is correlated with reduced growth rates in neonatal swine. The specific physiological mechanisms contributing to this relationship are unknown. This study was performed to determine if AGP can modify muscle metabolism by examining glucose oxidation and protein synthesis in the C2C12 muscle cell line. Cells were used for experiments 4 days post-fusion as myotubes. Myotubes were exposed to AGP for 24 h, with the last 4 h used to monitor 14C-glucose oxidation or to measure protein synthesis by incorporation of 3H-tyrosine. Treatment of C2C12 myotubes with mouse AGP (100 µg/ml) reduced glucose oxidation (P0.05, n=6 trials), whereas incubation with both AGP and insulin reduced 3H-tyrosine release by 15% (P<0.01, n=6 trials). First, these data indicate that the acute phase protein AGP can interact with the skeletal muscle to reduce glucose oxidation, but this is not the result of an effect on glucose transport. Second, AGP can specifically reduce protein synthesis. Lastly, AGP can inhibit insulin-stimulated glucose oxidation, protein synthesis and breakdown.

Elevated alpha1-acid glycoprotein in gastric cancer patients inhibits the anticancer effects of paclitaxel, effects restored by co-administration of erythromycin.

Paclitaxel (PTX) which easily elutes into ascites is widely used to treat gastric cancer patients with peritoneal carcinomatosis (PC), but clinical outcomes are suboptimal. Increased concentrations of α1-acid glycoprotein (AGP), an important drug-binding protein, have been reported in the plasma and ascites of cancer patients. This study sought to clarify whether AGP binds to PTX and alters its anticancer effects. AGP concentrations were measured in the serum and ascites of gastric cancer patients with PC and in the serum of healthy volunteers. The in vitro effects of AGP and AGP plus erythromycin (EM) on PTX were evaluated by MTT assays in the gastric cancer cell lines. We also measured AGP concentrations in the ascites of PC model mice and examined the effects of EM plus PTX on PC. The mean AGP concentrations in the serum and ascites of gastric cancer patients with PC were 1524 and 834 µg/mL, respectively, higher than the mean AGP concentration of 650 µg/mL observed in the sera of healthy volunteers. AGP > 400 µg/mL significantly suppressed the cell growth inhibitory effect of PTX in vitro, but the co-administration of EM restored it. Elevated AGP concentrations were observed in the ascites of PC model mice. Administration of PTX alone did not markedly diminish PC, whereas co-administration of PTX and EM significantly reduced PC (p = 0.011). AGP is an important regulatory factor modulating the anticancer activity of intraperitoneal PTX. The co-administration of PTX and EM may be effective in treating gastric cancer patients with PC.

α 1-acid glycoprotein inhibits lipogenesis in neonatal swine adipose tissue.

Serum α1-acid glycoprotein (AGP) is elevated during late gestation and at birth in the pig and rapidly declines postnatally. In contrast, the pig is born with minimal lipid stores in the adipose tissue, but rapidly accumulates lipid during the first week. The present study examined if AGP can affect adipose tissue metabolism in the neonatal pig. Isolated cell cultures or tissue explants were prepared from dorsal subcutaneous adipose tissue of preweaning piglets. Porcine AGP was used at concentrations of 0, 100, 1000 and 5000 ng/ml medium in 24 h incubations. AGP reduced the messenger RNA (mRNA) abundance of the lipogenic enzymes, malic enzyme (ME), fatty acid synthase and acetyl coA carboxylase by at least 40% (P<0.001). The activity of ME and citrate lyase were also reduced by AGP (P<0.05). Glucose oxidation was reduced by treatment with 5000 ng AGP/ml medium (P<0.05). The 14C-glucose incorporation into fatty acids was reduced by ~25% by AGP treatment for 24 h with 1000 ng AGP/ml medium (P<0.05). The decrease in glucose metabolism by AGP appears to function through an inhibition in insulin-mediated glucose oxidation and incorporation into fatty acids. This was supported by the analysis of the mRNA abundance for sterol regulatory element-binding protein (SREBP), carbohydrate regulatory element-binding protein (ChREBP) and insulin receptor substrate 1 (IRS1), which all demonstrated reductions of at least 23% in response to AGP treatment (P<0.05). These data demonstrate an overall suppression of lipogenesis due to AGP inhibition of lipogenic gene expression in vitro, which the metabolic data and SREBP, ChREBP and IRS1 gene expression analysis suggest is through an inhibition in insulin-mediated events. Second, these data suggest that AGP may contribute to limiting lipogenesis within adipose tissue during the perinatal period, as AGP levels are highest for any serum protein at birth.

Orosomucoid 1 drives opportunistic infections through the polarization of monocytes to the M2b phenotype.

Orosomucoid (ORM, composed of two isoforms, ORM1 and ORM2) has been described as an inducer of M2 macrophages, which are cells that decrease host antibacterial innate immunities. However, it is unknown which phenotypes of M2 macrophages are induced by ORM. In this study, healthy donor monocytes stimulated with ORM (ORM-monocytes) were characterized phenotypically and biologically. CCL1 (a biomarker of M2b macrophages) and IL-10 were detected in monocyte cultures supplemented with ORM1; however, CCL17 (a biomarker of M2a macrophages) and CXCL13 (a biomarker of M2c macrophages) were not produced in these cultures. All of these soluble factors were not detected in the culture fluids of monocytes stimulated with ORM2. Monocytes stimulated with ORM1 were characterized as CD64(-)CD209(-)CD163(+)CCL1(+) cells. MRSA and Enterococcus faecalis infections were accelerated in chimeras (NOD/scid IL-2Rγ(null) mice reconstituted with white blood cells) after inoculation with monocytes stimulated with ORM1 or treatment with ORM1; however, the infections were greatly mitigated in both chimeras inoculated with ORM1-stimulated monocytes and treated with ORM1, after an additional treatment with an inhibitor of M2b macrophages (CCL1 antisense ODN). These results indicate that ORM1 stimulates quiescent monocytes to polarize to M2b monocytes. The regulation of M2b macrophages may be beneficial in controlling opportunistic infections in patients with a large amount of plasma ORM1.

α1-acid glycoprotein disrupts capillary-like tube formation of human lung microvascular endothelia.

PURPOSE: The acute phase protein, α1-acid glycoprotein, is expressed in the lung, and influences endothelial cell function. We asked whether it might regulate angiogenesis in human lung microvascular endothelia. MATERIALS AND METHODS: α1-acid glycoprotein was isolated from human serum by HPLC ion exchange chromatography. Its effects on endothelial cell functions including capillary-like tube formation on Matrigel, migration in a wounding assay, chemotaxis in a modified Boyden chamber, adhesion, and transendothelial flux of the permeability tracer, (14)C-albumin, were tested. RESULTS: α1-acid glycoprotein dose-dependently inhibited capillary-like tube formation without loss of cell viability. At ≥0.50 mg/mL, it inhibited tube formation >70%, and at 0.75 mg/mL, >97%. α1-acid glycoprotein dose- and time-dependently restrained EC migration into a wound as early as 2 hours, and in washout studies, did so reversibly. It was inhibitory against vascular endothelial growth factor-A and fibroblast growth factor-2-driven migration but failed to inhibit chemotactic responsiveness. When α1-acid glycoprotein was added to preformed tubes, it provoked their almost immediate disassembly. As early as 15 minutes, it induced tube network collapse without endothelial cell-cell disruption. It exerted a biphasic effect on cell adhesion to the Matrigel substrate. At lower concentrations (0.05-0.25 mg/mL), it increased cell adhesion, whereas at higher concentrations (≥0.75 mg/mL) decreased adhesion. In contrast, it had no effect on transendothelial (14)C-albumin flux. CONCLUSION: α1-acid glycoprotein, at concentrations found under physiological conditions, rapidly inhibits endothelial cell capillary-like tube formation that may be explained through diminished cell adhesion to the underlying matrix and/or reversibly decreased cell migration.

An acute-phase protein as a regulator of sperm survival in the bovine oviduct: alpha 1-acid-glycoprotein impairs neutrophil phagocytosis of sperm in vitro.

We have previously shown that polymorphonuclear neutrophils (PMNs) are present in bovine oviduct fluid under physiological conditions, and that the oviduct provides a microenvironment that protects sperm from phagocytosis by PMNs. Alpha 1-acid glycoprotein (AGP) is a major acute-phase protein produced mainly in the liver that has immunomodulatory functions. AGP mRNA is expressed in extrahepatic organs, such as the lung, kidney, spleen, lymph node, uterus, and ovary. Therefore, in this study, we investigated, 1) the local production of AGP in the bovine oviduct, 2) the effect of AGP on the phagocytic activity of PMNs for sperm and superoxide production and 3) the impact of AGP desialylation on the PMN phagocytosis of sperm. The AGP gene was expressed in cultured bovine oviduct epithelial cells (BOECs) and AGP protein was detected in oviduct fluid. Preexposure of PMNs to AGP at physiological levels impaired PMN phagocytosis for sperm and superoxide generation. The desialylation of AGP eliminated these suppressive effects of AGP on PMN. Scanning electron microscopy revealed that AGP drastically reduced the formation of DNA-based neutrophil extracellular traps (NETs) for sperm entanglement. Additionally, AGP dose-dependently stimulated BOECs to produce prostaglandin E2 (PGE2) which has been shown to partially contribute to the regulation of sperm phagocytosis in the bovine oviduct. AGP and PGE2 at concentrations detected in the oviducts additively suppressed sperm phagocytosis by PMNs. These results provide evidence that locally produced AGP may be involved in protecting sperm from phagocytosis by PMNs in the bovine oviduct.

Alpha-1 acid glycoprotein reduces hepatic leukocyte recruitment in murine models of either early endotoxemia or early sepsis.

OBJECTIVE: To characterize the effect of systemically administered AGP on early leukocyte recruitment in the livers of endotoxemic or septic mice and to determine whether this is influenced by LPS sequestration. METHODS: Endotoxemia was induced in C57Bl/6 mice via intraperitoneal injection of LPS. Sepsis was induced in mice by cecal ligation and perforation. AGP (165 mg/kg) or saline (20 mL/kg) or HAS (200 mg/kg) was administered immediately after surgery or LPS injection and the hepatic microcirculation was examined by intravital microscopy at four hour. RESULTS: Leukocyte adhesion in the PSV was reduced by treatment with AGP in mice subjected to either LPS or CLP protocols compared to either saline or HAS treatment. AGP-treated mice also had significantly higher sinusoidal flow in both models. Pre-incubation of LPS with AGP reduced the ability of LPS to recruit leukocytes to the liver microcirculation. CONCLUSIONS: AGP was more effective in limiting hepatic inflammation and maintaining perfusion than saline or HAS, in both endotoxemic and septic mice. AGP sequestration of LPS may contribute to its anti-inflammatory effects.

S-nitrosated α-1-acid glycoprotein kills drug-resistant bacteria and aids survival in sepsis.

Treating infections with exogenous NO, which shows broad-spectrum antimicrobial activity, appears to be effective. Similar to NO biosynthesis, biosynthesis of α-1-acid glycoprotein variant A (AGPa), with a reduced cysteine (Cys149), increases markedly during inflammation and infection. We hypothesized that AGPa is an S-nitrosation target in acute-phase proteins. This study aimed to determine whether S-nitrosated AGPa (SNO-AGPa) may be the first compound of this novel antibacterial class against multidrug-resistant bacteria. AGPa was incubated with RAW264.7 cells activated by lipopolysaccharide and interferon-γ. The antimicrobial effects of SNO-AGPa were determined by measuring the turbidity of the bacterial suspensions in vitro and survival in a murine sepsis model in vivo, respectively. Results indicated that endogenous NO generated by activated RAW264.7 cells caused S-nitrosation of AGPa at Cys149. SNO-AGPa strongly inhibited growth of gram-positive, gram-negative, and multidrug-resistant bacteria and was an extremely potent bacteriostatic compound (IC(50): 10(-9) to 10(-6) M). The antibacterial mechanism of SNO-AGPa involves S-transnitrosation from SNO-AGPa to bacterial cells. Treatment with SNO-AGPa, but not with AGPa, markedly reduced bacterial counts in blood and liver in a mouse sepsis model. The sialyl residues of AGPa seem to suppress the antibacterial activity, since SNO-asialo AGPa was more potent than SNO-AGPa.

Construction and characterization of an anti-asialoglycoprotein receptor single-chain variable-fragment-targeted melittin.

Antibody-therapeutic agent conjugation to be delivered specifically to tumor cells is required for many target-based therapeutic strategies. In the present study, a recombinant immunotoxin was constructed by which melittin was fused to an anti-asialoglycoprotein receptor (ASGPR) single-chain variable fragment antibody (C1), and targeting ability and cytolytic efficacy of the fusion protein were studied. Our results suggested that the recombinant 29.4 kDa protein C1M was expressed in Escherichia coli as a soluble style. Binding of C1M to the surface of hepatocellular carcinoma (HCC) cells was confirmed by both immunohistochemistry and flow cytometry assays. C1M kept the hemolytic activity of melittin and exhibited cytolytic capacity to HepG2 cells at a concentration of 1.5 µg/mL, under which erythrocytes would not be lysed. The effects were greatly inhibited by coadministration with asialoorosomucoid, a natural ligand for ASGPR. These results suggested that C1M conferred targeting and ASGPR-specific cytotoxicity to HCC cells. This work makes it possible to further investigate its antihepatoma efficacy in vivo.

Nucleoside transport inhibitors: structure-activity relationships for pyrimido[5,4-d]pyrimidine derivatives that potentiate pemetrexed cytotoxicity in the presence of α1-acid glycoprotein.

Membrane transport of nucleosides or nucleobases is mediated by transporters including the equilibrative nucleoside transporters (ENTs), and resistance to antitumor antimetabolite drugs may arise via salvage of exogenous purine or pyrimidine nucleosides or nucleobases by ENT transporters. The therapeutic utility of dipyridamole (3), a potent ENT inhibitor, is compromised by binding to the serum protein α(1)-acid glycoprotein (AGP). Derivatives and prodrugs of the ENT inhibitor 4,8-bis[(3,4-dimethoxybenzyl)amino]-2,6-bis[(2-hydroxypropyl)amino]pyrimido[5,4-d]pyrimidine (6, NU3108) are described, with improved in vivo pharmacokinetic properties and reduced AGP binding relative to dipyridamole. The mono- and diglycine carbamate derivatives were at least as potent as 6 and showed no reduction in potency by AGP. In a [(3)H]thymidine incorporation assay, employing COR-L23 cells, the diastereoisomers of 6 (IC(50) = 26 nM) exhibited activity comparable with 3 (IC(50) = 15 nM). The monophenyl carbamate and mono-4-methoxyphenyl carbamate exhibited the best ENT-inhibitory activity in the COR-L23 assay (IC(50) = 8 and 4 nM, respectively). All of the new prodrugs were also highly effective at reversing thymidine/hypoxanthine rescue from pemetrexed cytotoxicity in the COR-L23 cell line.

Investigating clearance mechanisms for recombinant activated factor VII in a perfused liver model.

Clearance mechanisms for recombinant activated human FVII (rFVIIa; NovoSeven), a heterogeneously glycosylated protein, have yet to be fully elucidated, but may involve the liver. The effects of the gamma-carboxy glutamic acid (Gla) domain and the sialic acid content of the protein on rFVIIa clearance were investigated following intravenous administration of rFVIIa lacking the Gla domain, des(1-44) rFVIIa and asialo-rFVIIa in pharmacokinetic (PK) studies and perfused rat livers. PK parameters for both rFVIIa and des(1-44) rFVIIa had similar biphasic clearance profiles, as well as half-lives ([t(1/2)]=80 and 88 minutes, respectively), while asialo-rFVIIa was cleared quickly (t(1/2)=21 minutes) with a linear clearance profile. Perfused liver studies with all proteins (10 nM) mirrored the trends in profiles observed in the PK study. rFVIIa and des(1-44) rFVIIa were cleared to a similar extent, 41% and 35%, respectively, after 1 h, whereas plasma-derived FVII from humans (which has a higher sialylation content than rFVIIa) was cleared to a lesser extent (21%). Asialo-rFVIIa, on the other hand, was almost totally cleared and when an excess of asialo-orosomucoid was added to the perfusate, its clearance was significantly reduced (by 34%) and also for rFVIIa, albeit to a lesser extent (by 14%). Together these data suggest that carbohydrate receptor(s) (e.g. the asialoglycoprotein receptor, ASGPR) play a role in asialo-rFVIIa and rFVIIa clearance. In vivo and liver clearance data correlated well showing similar trends and indicated that rFVIIa clearance is not affected by the Gla domain, but rather by a subpopulation of N-glycosylated structures on rFVIIa.

Modulation of the blood-brain barrier permeability by plasma glycoprotein orosomucoid.

Previous studies have shown that the glycoprotein orosomucoid modulates permeability of peripheral microvessels to charged molecules by contributing to the net charge on the microvessel wall. To investigate whether or not orosomucoid also modulates the permeability of the blood-brain barrier (BBB) by a similar mechanism, we measured the permeability (P) of rat pial microvessels to similar-sized molecules with different charges: alpha-lactalbumin (-10, Stokes radius 2.08 nm) and ribonuclease (+4, Stokes radius 2.01 nm). Tests were performed under control conditions with a Ringer-BSA (bovine serum albumin) perfusate and with 0.1mg/ml orosomucoid in Ringer-BSA perfusate. The pial circulation was observed through a section of frontoparietal bones thinned with a micro-grinder, and P was determined using a quantitative fluorescence video microscopy. In the absence of orosomucoid, the permeability of pial microvessels to positively charged ribonuclease was 4-fold that to negatively charged alpha-lactalbumin. In contrast, in the presence of orosomucoid, permeability to ribonuclease was 12-fold that to alpha-lactalbumin. On the basis of these experimental data, our theoretical model predicted that the charge density of the endothelial glycocalyx layer at the luminal surface of the BBB increased 2.8-fold in the presence of 0.1 mg/ml orosomucoid, while the charge density of the BBB basement membrane increased 1.8-fold, compared to their control values. Our results indicate that orosomucoid can modulate the permeability of the BBB to charged molecules by adding negative charge to the matrix components of the BBB.