Histidine-rich Glycoprotein Levels Research Articles

Histidine-rich glycoprotein modulates neutrophils and thrombolysis-associated hemorrhagic transformation

Intravenous thrombolysis using recombinant tissue plasminogen activator (tPA) remains the primary treatment for patients with acute ischemic stroke (AIS). However, the mechanism of tPA-related hemorrhagic transformation (HT) remains poorly understood. Elevation of histidine-rich glycoprotein (HRG) expression was detected by nano-liquid chromatography tandem mass spectrometry at 1 h following tPA infusion as compared to baseline prior to tPA infusion (discovery cohort, n = 10), which was subsequently confirmed in a validation cohort (n = 157) by ELISA. Surprisingly, no elevation of HRG was detected in individuals who subsequently developed HT. During in vitro experiments, HRG reduced neutrophil NETosis, inflammatory cytokine production, and migration across the blood–brain barrier induced by tPA. In a photothrombotic murine AIS model, HRG administration ameliorated HT with delayed thrombolysis, by inhibiting neutrophil immune infiltration and downregulating pro-inflammatory signaling pathways. Neutrophil depletion or NETosis inhibition also alleviated HT, whereas HRG siRNA treatment exacerbated HT. In conclusion, fluctuations in HRG levels may reflect tPA therapy and its associated HT. The inhibitory effect of HRG on neutrophils may counteract tPA-induced immune abnormalities and HT in patients with AIS.

Insights Into the Role of miR-877 and Histidine-Rich Glycoprotein in Preeclampsia

IntroductionThe clinical significance of miR-877 and histidine-rich glycoprotein (HRG) in preeclampsia (PE) remains unknown. Bioinformatics analyses have identified HRG as a target for numerous micro RNAs. Based on novelty and target score, miR-877 was selected for this study to assess the clinical significance of miR-877 and HRG in placental and serum samples from patients with PE, with the aim of elucidating their potential role in disease progression.Material and methodsThis study included 75 placental tissue samples and 75 serum samples obtained from patients with PE and normal controls. The PE group was subdivided into mild and severe cases. Relative quantification of miR-877 and HRG was performed using quantitative reverse transcriptase–polymerase chain reaction and enzyme-linked immunosorbent assay, respectively.ResultsPlacental and serum miR-877 levels were significantly elevated in pregnancies with PE, especially in severe cases, compared to normal controls. However, there were significant reductions in HRG serum levels along with significant increases in placental HRG levels among patients with PE. Moreover, significant differences in miR-877 and HRG levels were noted between the PE and control groups.ConclusionsmiR-877 and HRG may play a role in the pathogenesis and progression of PE. Moreover, miR-877 potentially plays a role in the dysregulation of HRG. In addition, these molecules are potential biomarkers for the detection of PE as well as differentiation of mild and severe cases.

CHANGES OF HISTIDINE-RICH GLYCOPROTEIN LEVELS IN CRITICALLY ILL SEPTIC PATIENTS.

Background: Histidine-rich glycoprotein (HRG), a potential prognostic factor in sepsis, lacks clarity regarding its relevance in septic-induced shock, disseminated intravascular coagulation (DIC), and acute respiratory distress syndrome (ARDS) pathogenesis. This study investigated the association between HRG concentrations and these critical conditions. Methods: Blood samples were collected from 53 critically ill patients on days 1, 3, 5, and 7 after ICU admission at the Kyushu University Hospital. Daily clinical and laboratory data were recorded, and patient survival was assessed 28 days after ICU admission. Results: Serum HRG concentrations were significantly reduced on days 3, 5, and 7 in patients with septic shock and DIC but not in those with ARDS. While initial HRG levels on day one were not correlated with survival, nonsurvivors displayed decreased HRG levels, notably on days 3, 5, and 7 post-ICU admissions. The HRG levels remained stable in survivors. A progressive decrease was associated with higher mortality rates, particularly on days 5 and 7. On day 5, an HRG level with a cutoff of 25.5 μg/mL showed a sensitivity of 0.77 and a specificity of 0.75, indicating significantly lower survival rates (log-rank test, P < 0.05). Conclusion: HRG presents a potential intervention for critically ill sepsis patients, providing a novel strategy to enhance outcomes. Further research is needed to explore the therapeutic potential of HRG in sepsis management.

Histidine-rich glycoprotein attenuates catheter thrombosis.

Factor XII (FXII) knockdown attenuates catheter thrombosis in rabbits. Because histidine-rich glycoprotein (HRG) modulates FXIIa activity, we hypothesized that HRG depletion would promote catheter thrombosis. To test this, rabbits were given either antisense oligonucleotides (ASOs) against HRG or FXII, a control ASO, or saline. The activated partial thromboplastin time (aPTT), prothrombin time (PT), and catheter-induced thrombin generation were determined in blood collected before and after treatment. Compared with the controls, the HRG- and FXII-directed ASOs reduced hepatic messenger RNA and plasma levels of HRG and FXII, respectively, by >90%. Although HRG knockdown shortened the aPTT by 2.5 fold, FXII knockdown prolonged it by fourfold; neither of the ASOs affected the PT. Catheter segments shortened the lag time and increased peak thrombin in the plasma from control rabbits; effects were significantly enhanced and attenuated in the plasma from rabbits given the HRG- and FXII-directed ASOs, respectively. Catheters were then inserted into the right external jugular vein of the rabbits, and the time for catheter occlusion was determined. The catheter occlusion times with the control ASO or saline were 62± 8minutes and 60± 11minutes, respectively. The occlusion time was significantly reduced to 34± 9minutes, with HRG knockdown and significantly prolonged to 128± 19minutes with FXII knockdown. HRG levels are decreased with sepsis or cancer, and such patients are prone to catheter thrombosis. Because HRG modulates catheter thrombosis, our findings suggest that HRG supplementation may prevent this problem.

Proteogenomic Features of the Highly Polymorphic Histidine-rich Glycoprotein Arose Late in Evolution

Histidine-rich glycoprotein (HRG) is a liver-produced protein circulating in human serum at high concentrations of around 125 μg/ml. HRG belongs to the family of type-3 cystatins and has been implicated in a plethora of biological processes, albeit that its precise function is still not well understood. Human HRG is a highly polymorphic protein, with at least five variants with minor allele frequencies of more than 10%, variable in populations from different parts of the world. Considering these five mutations we can theoretically expect 35 = 243 possible genetic HRG variants in the population. Here, we purified HRG from serum of 44 individual donors and investigated by proteomics the occurrence of different allotypes, each being either homozygote or heterozygote for each of the five mutation sites. We observed that some mutational combinations in HRG were highly favored, while others were apparently missing, although they ought to be present based on the independent assembly of these five mutation sites. To further explore this behavior, we extracted data from the 1000 genome project (n ∼ 2500 genomes) and assessed the frequency of different HRG mutants in this larger dataset, observing a prevailing agreement with our proteomics data. From all the proteogenomic data we conclude that the five different mutation sites in HRG are not occurring independently, but several mutations at different sites are fully mutually exclusive, whereas others are highly intwined. Specific mutations do also affect HRG glycosylation. As the levels of HRG have been suggested as a protein biomarker in a variety of biological processes (e.g., aging, COVID-19 severity, severity of bacterial infections), we here conclude that the highly polymorphic nature of the protein needs to be considered in such proteomics evaluations, as these mutations may affect HRG’s abundance, structure, posttranslational modifications, and function.

Consistently low levels of histidine-rich glycoprotein as a new prognostic biomarker for sepsis: A multicenter prospective observational study.

Few sepsis biomarkers accurately predict severity and mortality. Previously, we had reported that first-day histidine-rich glycoprotein (HRG) levels were significantly lower in patients with sepsis and were associated with mortality. Since the time trends of HRG are unknown, this study focused on the time course of HRG in patients with sepsis and evaluated the differences between survivors and non-survivors. A multicenter prospective observational study was conducted involving 200 patients with sepsis in 16 Japanese hospitals. Blood samples were collected on days 1, 3, 5, and 7, and 28-day mortality was used for survival analysis. Plasma HRG levels were determined using a modified quantitative sandwich enzyme-linked immunosorbent assay. First-day HRG levels in non-survivors were significantly lower than those in survivors (mean, 15.7 [95% confidence interval (CI), 13.4-18.1] vs 20.7 [19.5-21.9] μg/mL; P = 0.006). Although there was no time × survivors/non-survivors interaction in the time courses of HRG (P = 0.34), the main effect of generalized linear mixed models was significant (P < 0.001). In a univariate Cox proportional hazards model with each variable as a time-dependent covariate, higher HRG levels were significantly associated with a lower risk of mortality (hazard ratio, 0.85 [95% CI, 0.78-0.92]; P < 0.001). Furthermore, presepsin levels (P = 0.02) and Sequential Organ Function Assessment scores (P < 0.001) were significantly associated with mortality. Harrell's C-index values for the 28-day mortality effect of HRG, presepsin, procalcitonin, and C-reactive protein were 0.72, 0.70, 0.63, and 0.59, respectively. HRG levels in non-survivors were consistently lower than those in survivors during the first seven days of sepsis. Repeatedly measured HRG levels were significantly associated with mortality. Furthermore, the predictive power of HRG for mortality may be superior to that of other singular biomarkers, including presepsin, procalcitonin, and C-reactive protein.

Longitudinal Measurement of Histidine-Rich Glycoprotein Levels in Bronchopulmonary Dysplasia: A Pilot Study.

Histidine-rich glycoprotein (HRG) has been reported to inhibit signaling leading to the release of high mobility group box 1 protein, a damage-associated molecular pattern. The present study aimed to determine the longitudinal change in HRG levels in extremely preterm infants and assess whether complications such as bronchopulmonary dysplasia (BPD) were associated with differences in HRG levels. In this multicenter, prospective, observational study, we measured serum HRG levels every 2 weeks from birth to 8 weeks of age. Serum HRG was measured using an enzyme-linked immunosorbent assay. We included 19 extremely preterm infants in the study and 74 samples were analyzed. The median gestational age was 26.0 weeks, and the median birth weight was 858 g. Serum HRG levels showed a significant upward trend after birth (p &lt; 0.001); median HRG concentrations at birth and at 2, 4, 6, and 8 weeks of age were 1.07, 1.11, 2.86, 6.05, and 7.49 µg/mL, respectively. Onset of BPD was not associated with differences in serum HRG levels. Further, the serum HRG levels increased significantly after birth in extremely preterm infants.

Histidine-Rich Glycoprotein Suppresses the S100A8/A9-Mediated Organotropic Metastasis of Melanoma Cells.

The dissection of the complex multistep process of metastasis exposes vulnerabilities that could be exploited to prevent metastasis. To search for possible factors that favor metastatic outgrowth, we have been focusing on secretory S100A8/A9. A heterodimer complex of the S100A8 and S100A9 proteins, S100A8/A9 functions as a strong chemoattractant, growth factor, and immune suppressor, both promoting the cancer milieu at the cancer-onset site and cultivating remote, premetastatic cancer sites. We previously reported that melanoma cells show lung-tropic metastasis owing to the abundant expression of S100A8/A9 in the lung. In the present study, we addressed the question of why melanoma cells are not metastasized into the brain at significant levels in mice despite the marked induction of S100A8/A9 in the brain. We discovered the presence of plasma histidine-rich glycoprotein (HRG), a brain-metastasis suppression factor against S100A8/A9. Using S100A8/A9 as an affinity ligand, we searched for and purified the binding plasma proteins of S100A8/A9 and identified HRG as the major protein on mass spectrometric analysis. HRG prevents the binding of S100A8/A9 to the B16-BL6 melanoma cell surface via the formation of the S100A8/A9 complex. HRG also inhibited the S100A8/A9-induced migration and invasion of A375 melanoma cells. When we knocked down HRG in mice bearing skin melanoma, metastasis to both the brain and lungs was significantly enhanced. The clinical examination of plasma S100A8/A9 and HRG levels showed that lung cancer patients with brain metastasis had higher S100A8/A9 and lower HRG levels than nonmetastatic patients. These results suggest that the plasma protein HRG strongly protects the brain and lungs from the threat of melanoma metastasis.

Histidine-rich glycoprotein as a novel predictive biomarker of postoperative complications in intensive care unit patients: a prospective observational study

BackgroundDecrease in histidine-rich glycoprotein (HRG) was reported as a cause of dysregulation of the coagulation-fibrinolysis and immune systems, leading to multi-organ failure, and it may be a biomarker for sepsis, ventilator-associated pneumonia, preeclampsia, and coronavirus disease 2019. However, the usefulness of HRG in perioperative management remains unclear. This study aimed to assess the usefulness of HRG as a biomarker for predicting postoperative complications.MethodsThis was a single-center, prospective, observational study of 150 adult patients who were admitted to the intensive care unit after surgery. Postoperative complications were defined as those having a grade II or higher in the Clavien–Dindo classification, occurring within 7 days after surgery. The primary outcome was HRG levels in the patients with and without postoperative complications. The secondary outcome was the ability of HRG, white blood cell, C-reactive protein, procalcitonin, and presepsin to predict postoperative complications. Data are presented as number and median (interquartile range).ResultsThe incidence of postoperative complications was 40%. The HRG levels on postoperative day 1 were significantly lower in patients who developed postoperative complications (n = 60; 21.50 [18.12–25.74] µg/mL) than in those who did not develop postoperative complications (n = 90; 25.46 [21.05–31.63] µg/mL). The Harrell C-index scores for postoperative complications were HRG, 0.65; white blood cell, 0.50; C-reactive protein, 0.59; procalcitonin, 0.73; and presepsin, 0.73. HRG was independent predictor of postoperative complications when adjusted for age, the presence of preoperative cardiovascular comorbidities, American Society of Anesthesiologists Physical Status Classification, operative time, and the volume of intraoperative bleeding (adjusted hazard ratio = 0.94; 95% confidence interval, 0.90–0.99).ConclusionsThe HRG levels on postoperative day 1 could predict postoperative complications. Hence, HRG may be a useful biomarker for predicting postoperative complications.

Decreased levels of histidine-rich glycoprotein and increased levels of high-mobility group box 1 are risk factors for refractory Kawasaki disease.

Histidine-rich glycoprotein (HRG) and high-mobility group box 1 (HMGB1) regulate the activation of neutrophils and vascular endothelium. The aim of this study was to quantify HRG and HMGB1 levels in patients with Kawasaki disease (KD) and evaluate their use in the clinical management of KD. This study was prospectively performed. Patients were divided into two groups and analysed depending on whether KD symptoms improved by Day 10 of illness. HRG, HMGB1, and other laboratory variables were measured before the first treatment in all cases and, in most cases, afterwards for assessing trends. In this prospective study, we enrolled 60 patients with KD and 48 healthy controls. The HRG level in the KD group was significantly lower than that in the healthy control group; HMGB1 levels showed no obvious differences. In the KD group, HRG levels were negatively correlated with white blood cell and neutrophil counts. In the poor responders and responders groups, a tendency for a decrease in HRG and HMGB1 levels, respectively, was observed from pretreatment to post-treatment. HRG and HMGB1 are related to the pathogenesis of KD; low HRG and high HMGB1 levels cause resistance against KD treatment.

Comparison of Histidine rich glycoprotein, a novel biomarker for sepsis, with traditional biomarkers in adult ICU patients

Sepsis is a major public healthcare problem. It remains a significant cause of morbidity and mortality in intensive care units (ICU) all over the world. A lifesaving early specific diagnosis and treatment is a challenge as no gold standard technique exists that can alone allow a rapid and reliable diagnosis of sepsis. Histidine-rich glycoprotein (HRG) is a promising new biomarker of sepsis that can contribute to enhance current sepsis diagnostic tools. The current study aimed to evaluate HRG as a diagnostic biomarker for sepsis compared to the conventionally used biomarkers, procalcitonin (PCT) and C-reactive protein (CRP). The study included 67 participants classified into 3 groups: Control (n=19), systemic inflammatory response syndrome (SIRS) patients (n=24) and sepsis patients (n=24). Serum HRG, CRP and PCT levels were measured by ELISA techniques. HRG level was significantly reduced in sepsis patients compared with SIRS patients (P < 0.001) and controls (P < 0.001) with overall statistically significant differences between the three groups (P < 0.001). Serum levels of the 3 biomarkers revealed increased PCT level in SIRS and sepsis groups, (P=0.002 and p < 0.001 respectively), CRP level significantly increased in sepsis (P < 0.001) but not in SIRS patients (P=0.525). The area under the curve (AUC) value was 0.988 for HRG, 0.966 for PCT and 0.859 for CRP respectively. The sensitivity, specificity, PPV and NPV for diagnosis of HRG were 95.8%, 93%, 88.5%, and 97.6%, respectively. In conclusion, HRG could be a good indicator for sepsis, that can discriminate sepsis and SIRS patients in ICU.

Prognostic Value of Histidine-Rich Glycoprotein for Community-Acquired Pneumonia.

Purpose Histidine-rich glycoprotein (HRG) is abundant in serum and has been implicated in several processes including blood coagulation and immune response. This prospective study is aimed at exploring HRG as a biomarker in patients hospitalized for community-acquired pneumonia (CAP). Methods A total of 160 patients (73 severe CAP, 57 nonsevere CAP), and 30 healthy controls were enrolled in 2019. Demographic and clinical data were recorded for all patients. Serum HRG concentration was measured upon admission using ELISA. Results HRG levels were significantly lower in severe CAP patients compared with other groups, regardless of etiology, and were negatively correlated with serum interleukin-6 and disease severity index scores. Combination of CURB-65, PSI, and APACHE II scores with HRG values significantly improved the accuracy of predicting 30-day mortality in these patients. Cox regression analysis showed that HRG could serve as an independent risk factor for 30-day mortality. Notably, patients with HRG ≤ 16.92 μg/mL had significantly lower cumulative survival than those with HRG > 16.92 μg/mL. Conclusion Serum HRG levels are lower in patients with severe CAP and are negatively correlated with disease severity scores. Measurement of HRG upon admission can provide valuable prognostic information for patients with CAP.

Histidine-rich glycoprotein as a prognostic biomarker for sepsis

Various biomarkers have been proposed for sepsis; however, only a few become the standard. We previously reported that plasma histidine-rich glycoprotein (HRG) levels decreased in septic mice, and supplemental infusion of HRG improved survival in mice model of sepsis. Moreover, our previous clinical study demonstrated that HRG levels in septic patients were lower than those in noninfective systemic inflammatory response syndrome patients, and it could be a biomarker for sepsis. In this study, we focused on septic patients and assessed the differences in HRG levels between the non-survivors and survivors. We studied ICU patients newly diagnosed with sepsis. Blood samples were collected within 24 h of ICU admission, and HRG levels were determined using an enzyme-linked immunosorbent assay. Ninety-nine septic patients from 11 institutes in Japan were included. HRG levels were significantly lower in non-survivors (n = 16) than in survivors (n = 83) (median, 15.1 [interquartile ranges, 12.7–16.6] vs. 30.6 [22.1–39.6] µg/ml; p < 0.01). Survival analysis revealed that HRG levels were associated with mortality (hazard ratio 0.79, p < 0.01), and the Harrell C-index (predictive power) for HRG was 0.90. These results suggested that HRG could be a novel prognostic biomarker for sepsis.

Early Prediction Model of Gestational Hypertension by Multi-Biomarkers Before 20 Weeks Gestation.

BackgroundGestational hypertension (GH), a hypertensive disorder of pregnancy (HDP), is a leading cause of maternal and fetal mortality due to the lack of clarity on its exact etiology and clinically feasible prediction models. This study was performed to discover novel biomarkers before 20 weeks gestation and thereby construct an early GH prediction model.MethodsThis study was designed based on differentially expressed protein screening followed by clinical validation. In the screening phase, a nested case-controlled study was conducted by plasma proteomic analyses using label-free LC-MS/MS and plasma samples from seven pre-GH cases before 20-week gestation and seven age- and gestational week-matched controls. In the validation phase, 10 proteins with differential expression in the screening phase were validated by ELISA or electrochemiluminescence in an independent study consisting of 29 pre-GH cases before 20-week gestation and 29 matched controls.ResultsIn the screening phase, 149 proteins were found to be differentially expressed between the two groups and were predominantly involved in complement and coagulation cascades, platelet degranulation and positive regulation of cell motility. Further validation showed that serpin family C member 1 (SERPINC1), serpin family A member 5 (SERPINA5), complement factor H-related protein 5 (CFHR5), clusterin, cytokeratin 18 (CK18) and histidine-rich glycoprotein (HRG) levels were significantly higher in women who later developed GH compared to women with uncomplicated pregnancies (P<0.05). Binary logistic regression analysis was used to determine the combination efficacy of models for early prediction of GH. The model with a combination of SERPINC1, CK18 and HRG had a significantly better discriminatory power (AUC = 0.91, 95% CI 0.83–0.98) compared to the models with those proteins alone as independent predictors of GH.ConclusionPlasma levels of SERPINC1, SERPINA5, CFHR5, clusterin, CK18 and HRG are potential novel predictive biomarkers of GH, and a prediction model using a combination of SERPINC1, CK18 and HRG has good discriminatory performance for GH before 20 weeks gestation.

Histidine-Rich Glycoprotein Functions as a Dual Regulator of Neutrophil Activity in Horses

Histidine-rich glycoprotein (HRG) is an abundant plasma protein that has been identified in most mammals. We first identified whole genome sequence of equine HRG (eHRG) and succeeded to purify eHRG from plasma of horses. Since HRG interacts with various ligands, this protein is thought to be involved in immune response, coagulation, and angiogenesis. Systemic inflammatory response syndrome (SIRS) is characterized as a non-specific, clinical, pro-inflammatory immune response that damage organs and tissues in the host. Recent reports revealed that blood HRG levels in human patients with SIRS are approximately 50% lower than those in healthy controls, indicating the use of HRG as a biomarker or treatment for SIRS. SIRS is also a serious issue in equine medicine. In this study, we investigated various effects of eHRG on neutrophil functions, including adhesion, migration, phagocytosis, reactive oxygen species (ROS) production, and lysosome maturation using neutrophils isolated from horses. Microscopic observation showed that the addition of eHRG to the culture diminished adhesion of neutrophils stimulated with LPS. Using the Boyden chamber technique, we showed that eHRG reduced neutrophil chemotaxis induced by recombinant human IL-8. Luminol-dependent chemiluminescence assay demonstrated that eHRG restrained the peak of LPS-promoted ROS production from neutrophils. In contrast, eHRG promoted phagocytic activity evaluated with uptake of fluorescent dye conjugated particles, as well as lysosomal maturation assessed using fluorescent staining for lysosomes of equine neutrophils. These results indicated that eHRG acts as a dual regulator of neutrophils in horses.

Plasma Levels of Histidine-Rich Glycoprotein are Associated with the Development of Primary Graft Dysfunction after Lung Transplantation

<h3>Purpose</h3> Histidine-rich glycoprotein (HRG) is a 75 kDa plasma glycoprotein produced in and secreted from the liver. Recently, supplementary HRG treatment has been shown to inhibit acute respiratory distress syndrome (ARDS) and prevent septic lethality. The pathogenesis of primary graft dysfunction (PGD) after lung transplantation (LT) could be similar to that of ARDS. However, the relationship between plasma levels of HRG and PGD after LT remains unknown. <h3>Methods</h3> Blood samples were collected from a total of 68 patients who underwent LT, including the patients with PGD grade 0-1 (the non-PGD group, n = 43), those with PGD grade 2 (the moderate PGD group, n = 18) and those with PGD grade 3 (the severe PGD group, n = 7) at 72 hours after LT. Plasma levels of HRG were quantified using ELISA and compared among the three groups. Appropriate cut-off values of HRG levels were set for overall survival (OS) after LT. <h3>Results</h3> The median follow-up period was 1208 (286-2982) days. Plasma levels of HRG at 72 hours after LT in the severe PGD group were significantly lower than those of the other groups (the non-PGD group vs. the severe PGD group, P = 0.042; the moderate PGD group vs. the severe PGD group, P = 0.040) (Fig. 1). An ROC analysis of the performance of plasma levels of HRG as a marker of overall survival yielded an AUC of 0.61 at a threshold level of 34.4 µg/mL. Patients with plasma levels of HRG ≥ 34.4 µg/mL showed significantly better OS and chronic lung allograft dysfunction (CLAD) free survival than those with plasma levels of HRG < 34.4 µg/mL (OS, P = 0.037; CLAD-free survival, P = 0.046) (Fig. 2). <h3>Conclusion</h3> Plasma level of HRG at 72 hours after LT was associated with the development of PGD, suggesting its usefulness as a predictor of the development of CLAD and survival after LT.

Plasma Proteomic Profile Associated with Platelet Dysfunction after Trauma

Background. Coagulopathic bleeding is a major cause of mortality after trauma, and platelet dysfunction contributes to this problem. The causes of platelet dysfunction are unknown, but a great deal can be learned from the plasma environment after injury, which may directly alter platelet function. Studying the changes in plasma using untargeted proteomics would provide unbiased insight into the presence of possible inhibitors of platelet function, changes to their major ligands, or other previously unknown pathways affecting platelet function. Methods. Citrated blood was collected from severely injured trauma patients at the time of their arrival to the Emergency Department. Platelet testing was performed immediately, and plasma was frozen for analysis. Samples were collected from 110 patients, and a subset of 24 patients was identified by a preserved (n=12) or severely impaired (n=12) platelet aggregation response to five different agonists (adenosine diphosphate, arachidonic acid, collagen, thrombin receptor-activating peptide, and ristocetin). Untargeted proteomics was performed by nanoflow liquid chromatography tandem mass spectrometry to determine the plasma protein profile associated with platelet dysfunction. Protein abundance levels for each patient were normalized to total protein concentration to control for hemodilution by crystalloid fluid infusion prior to blood draw. Results were compared by Wilcoxon rank-sum test, and a two-tailed p value less than 0.05 was considered significant. No adjustment was made for multiple comparisons, as the risk of a type II error was felt to outweigh that of a type I error in this exploratory analysis. Results. Patients with platelet dysfunction were more severely injured (median Injury Severity Score 29.5 vs. 13.5, p=0.002) but otherwise demographically similar to those with retained platelet function. Of 232 proteins identified, twelve were significantly different in the low- vs. high-platelet function groups: gelsolin (median peak intensity 9.70E+6 vs. 1.48 E+7, p=0.002), transketolase (2.86E+4 vs. 9.36E+3, p=0.003), protein S100-A8 (4.60E+4 vs. 2.64E+4, p=0.006) and -A9 (5.83E+4 vs. 4.07E+4, p=0.012), histone H4 (5.72E+4 vs. 8.47E+6, p=0.007), histidine-rich glycoprotein (HRG) (5.00E+6 vs. 8.30E+6, p=0.008), factor XIII B chain (1.09E+6 vs. 1.61E+6, p=0.020), apolipoprotein A-IV (2.30E+7 vs. 3.28E+7, p=0.024), alpha-enolase (1.02E+5 vs. 4.15E+4, p=0.024), heat shock protein 90-alpha (1.41E+4 vs. 4.08E+3, p=0.045), alpha-2-HS-glycoprotein (2.83E+7 vs. 3.68E+7, p=0.045), and neutrophil gelatinase-associated lipocalin (3.44E+4 vs. 1.36E+4, p=0.045). These results are summarized in the figure, which shows one group of proteins that decreased in abundance (on the left side of the volcano plot) and another that increased (on the right side) in the patients with low platelet function. The twelve proteins that changed the most fall into several categories related to platelet function. Low gelsolin and high histone levels are each associated with microvascular obstruction by release of intracellular material that accumulates in small vessels and activates platelets. Low HRG and high damage-associated molecular pattern (DAMP) protein levels are consistent with massive innate immune activation, which can impair platelet function in many ways. Conclusion. This study provides an unbiased description of the change in proteomic profile associated with platelet dysfunction after trauma and identifies twelve proteins with the most profound changes. The pathways involving these proteins are salient targets for immediate investigation to better understand platelet dysfunction after trauma and identify targets for intervention. Figure Legend. Volcano plot depicting fold-change and statistical significance of individual proteins in patients with low vs. high platelet function. Dotted horizontal line represents p = 0.05. Twelve proteins showed a statistically significant p value. Figure Disclosures No relevant conflicts of interest to declare.

Increased levels of histidine-rich glycoprotein are associated with the development of post-thrombotic syndrome

Denser fibrin networks which are relatively resistant to lysis can predispose to post-thrombotic syndrome (PTS). Histidine-rich glycoprotein (HRG), a blood protein displaying antifibrinolytic properties, is present in fibrin clots. We investigated whether HRG may affect the risk of PTS in relation to alterations to fibrin characteristics. In venous thromboembolism (VTE) patients, we evaluated plasma HRG levels, plasma clot permeability, maximum absorbance, clot lysis time and maximum rate of increase in D-dimer levels released from clots after 3 months of the index event. We excluded patients with cancer and severe comorbidities. After 2 years of follow-up, 48 patients who developed PTS had 18.6% higher HRG at baseline. Baseline HRG positively correlated with clot lysis time, maximum absorbance, and thrombin-activatable fibrinolysis inhibitor (TAFI) activity but was inversely correlated with plasma clot permeability and maximum rate of increase in D-dimer levels released from clots. On multivariate regression model adjusted for age, fibrinogen and glucose, independent predictors of PTS were recurrent VTE, baseline HRG level, and TAFI activity. VTE recurred in 45 patients, including 30 patients with PTS, and this event showed no association with elevated HRG. Our findings suggest that increased HRG levels might contribute to the development of PTS, in part through prothrombotic fibrin clot properties.

Various functions of plasma histidine-rich glycoprotein and its clinical application as the biomarker and therapeutic drug for sepsis

Histidine-rich glycoprotein (HRG) is a 75 kDa plasma glycoprotein synthesized in liver mainly, which exists at approximately 60-100 μg/ml in human plasma. HRG is known to bind to several ligands and cells, leading to exert coagulation, fibrinolysis, immune and inflammation regulatory activity in septic condition. Thus, decreased plasma HRG level induces the dysregulations of coagulation, fibrinolysis and immune system, resulting in disseminated intravascular coagulation and multiple organ failure. This article focuses on the physiological activity of HRG and the potential of HRG as the biomarker and therapeutic drug for sepsis.

Levels of caspase-3 and histidine-rich glycoprotein in the embryo secretome as biomarkers of good-quality day-2 embryos and high-quality blastocysts.

Morphological assessment at defined developmental stages is the most important method to select viable embryos for transfer and cryopreservation. Timing of different developmental stages in embryo development has been shown to correlate with its potential to develop into a blastocyst. However, improvements in pregnancy rates by using time-lapse techniques have been difficult to validate scientifically. Therefore, there is a need for new methods, preferably non-invasive methods based on metabolomics, genomics and proteomics, to improve the evaluation of embryo quality even further. The aim of this study was to investigate if different levels of caspase-3 and histidine-rich glycoprotein (HRG), secreted by the embryo into the culture media, can be used as biomarkers of embryo quality. In this study, a total of 334 samples of culture media were collected from in vitro fertilization (IVF) treatments at three different clinics. Protein analysis of the culture media was performed using multiplex proximity extension protein analysis to detect levels of caspase-3 and HRG in the embryo secretome. Protein levels were compared in secretome samples from high- and low-quality blastocysts and embryos that became arrested during development. Correlation between protein levels and time to morula formation was also analyzed. Furthermore, protein levels in secretomes from day-2 cultured embryos were compared on the basis of whether or not pregnancy was achieved. The results showed that caspase-3 levels were lower in secretomes from high-quality vs. low-quality blastocysts and those that became arrested (p ≤ 0.05 for both). In addition, higher HRG levels correlated with a shorter time to morula formation (p ≤ 0.001). Caspase-3 levels were also lower in secretomes from day-2 cultured embryos resulting in a pregnancy vs. those that did not (p ≤ 0.05). Furthermore, it was shown that caspase-3 might be used as a marker for predicting potential success rate after transfer of day-2 cultured embryos, where a caspase-3 cutoff level of 0.02 gave a prediction probability of 68% (p = 0.038). In conclusion, in future prediction models, levels of caspase-3 and HRG might be used as potential markers of embryo quality, and secreted caspase-3 levels could to some extent predict the outcome after transfer of day-2 cultured embryos.