Apolipoprotein H, a new mediator in the inflammatory changes ensuring in jeopardised human myocardium

Accurate Diagnosis of COVID-19 from Self-Collectable Biospecimens Using Synthetic Apolipoprotein H Peptide-Coated Nanoparticle Assay

A high-throughput, accurate screening is crucial for the prevention and control of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Current methods, which involve sampling from the nasopharyngeal (NP) area by medical staffs, constitute a fundamental bottleneck in expanding the testing capacity. To meet the scales required for population-level surveillance, self-collectable specimens can be used; however, its low viral load has hindered its clinical adoption. Here, we describe a magnetic nanoparticle functionalized with synthetic apolipoprotein H (ApoH) peptides to capture, concentrate, and purify viruses. The ApoH assay demonstrates a viral enrichment efficiency of >90% for both SARS-CoV-2 and its variants, leading to an order of magnitude improvement in analytical sensitivity. For validation, we apply the assay to a total of 84 clinical specimens including nasal, oral, and mouth gargles obtained from COVID-19 patients. As a result, a 100% positivity rate is achieved from the patient-collected nasal and gargle samples, which exceeds that of the traditional NP swab method. The simple 12 min pre-enrichment assay enabling the use of self-collectable samples will be a practical solution to overcome the overwhelming diagnostic capacity. Furthermore, the methodology can easily be built on various clinical protocols, allowing its broad applicability to various disease diagnoses.

Effects of anti-beta 2-glycoprotein 1 antibodies and its association with pregnancy-related morbidity in antiphospholipid syndrome

Antiphospholipid syndrome (APS) is an autoimmune disease characterized by venous, arterial, or small-vessel thrombosis and/or pregnancy-related morbidity, associated with persistent positivity of antiphospholipid antibodies (aPL). Pregnancy-related morbidity in APS patients is characterized by unexplained fetal deaths, premature birth of morphologically normal newborns, and/or consecutive pregnancy losses before the 10^th week of gestation. Beta 2-glycoprotein 1 (ß2GP1) is the main antigen recognized by aPL and plays an essential role in the pathogenesis of APS. Antibodies against ß2GP1 (aß2GP1) are involved in damage-generating mechanisms in APS due to their interaction with trophoblasts, decidua, and endothelial cells. aß2GP1 might be used as a prognostic tool for obstetric risk stratification and ß2GP1 could be a target for molecular-targeted treatment to prevent pregnancy morbidity in APS. This review describes these aspects of aß2GP1, including effects on different cellular targets, its association with the severity of obstetric manifestations and the potential of ß2GP1-targeted therapies for APS.

Urine β-2-glycoprotein 1 as a biomarker for diagnosis of systemic lupus erythematosus

OBJECTIVE

The need for a biomarker with robust sensitivity and specificity in diagnosing systemic lupus erythematosus (SLE) remains unmet. Compared with blood samples, urine samples are more easily collected; thus, we aimed to identify such a biomarker based on urinary proteomics which could distinguish patients with SLE from healthy controls (HCs).

METHODS

Urine samples were collected from 76 SLE patients who visited rheumatology clinic in 2019 at Asan medical center and from 25 HCs. Urine proteins were analyzed using sequential windowed acquisition of all theoretical fragment ion spectra-mass spectrometry, and the candidate marker was confirmed by enzyme-linked immunosorbent assay (ELISA). Receiver operating characteristic curve analysis was used to determine the diagnostic value of the candidate biomarker.

RESULTS

Of 1157 proteins quantified, 153 were differentially expressed in urine samples from HCs. Among them were previously known markers including α-1-acid glycoprotein 1, α-2-HS-glycoprotein, ceruloplasmin, and prostaglandin-H2 D-isomerase. Moreover, the amount of β-2 glycoprotein (APOH) was increased in the urine of patients with SLE. The ELISA results also showed the level of urine APOH was higher in patients with SLE than in HCs and patients with rheumatoid arthritis. Moreover, the level was not different between SLE patients with and without nephritis. The urine APOH had an area under the curve value of 0.946 at a cut-off value of 228.53 ng/mg (sensitivity 91.5%, specificity 92.0%) for the diagnosis of SLE.

CONCLUSION

The results indicate that the urine APOH level can be an appropriate screening tool in a clinical setting when SLE is suspected.

Free Thiol β2-GPI (β-2-Glycoprotein-I) Provides a Link Between Inflammation and Oxidative Stress in Atherosclerotic Coronary Artery Disease

Objective:

Atherosclerotic coronary artery disease is well recognised as an inflammatory disorder that is also influenced by oxidative stress. β2-GPI (β-2-glycoprotein-I) is a circulating plasma protein that undergoes post-translational modification and exists in free thiol as well as oxidized forms. The aim of this study was to assess the association between these 2 post-translational redox forms of β2-GPI and atherosclerotic coronary artery disease.

Approach and Results:

Stable patients presenting for elective coronary angiography or CT coronary angiography were prospectively recruited. A separate group of patients after reperfused ST-segment–elevation myocardial infarction formed an acute coronary syndrome subgroup. All patients had collection of fasting serum and plasma for quantification of total and free thiol β2-GPI. Coronary artery disease extent was quantified by the Syntax and Gensini scores. A total of 552 patients with stable disease and 44 with acute coronary syndrome were recruited. While total β2-GPI was not associated with stable coronary artery disease, a higher free thiol β2-GPI was associated with its presence and extent. This finding remained significant after correcting for confounding variables, and free thiol β2-GPI was a better predictor of stable coronary artery disease than hs-CRP (high-sensitivity C-reactive protein). Paradoxically, there were lower levels of free thiol β2-GPI after ST-segment–elevation myocardial infarction.

Conclusions:

Free thiol β2-GPI is a predictor of coronary artery disease presence and extent in stable patients. Free thiol β2-GPI was a better predictor than high-sensitivity C-reactive protein.

The role of beta-2-glycoprotein I in health and disease associating structure with function: More than just APS

Beta-2-Glycoprotein I (β2GPI) plays a number of essential roles throughout the body. β2GPI, C-reactive protein and thrombomodulin are the only three proteins that possess the dual capability to up and down regulate the complement and coagulation systems depending upon external stimulus. Clinically, β2GPI is the primary antigen in the autoimmune condition antiphospholipid syndrome (APS), which is typically characterised by pregnancy morbidity and vascular thrombosis. This protein is also capable of adopting at least two distinct structural forms, but it has been argued that several other intermediate forms may exist. Thus, β2GPI is a unique protein with a key role in haemostasis, homeostasis and immunity. In this review, we examine the genetics, structure and function of β2GPI in the body and how these factors may influence its contribution to disease pathogenesis. We also consider the clinical implications of β2GPI in the diagnosis of APS and as a potentially novel therapeutic target.

Comparison of cytokine and gene activities in tissue and blood samples of patients with celiac disease

AIM

The aim of this study is to explore the expression of genes associated to celiac disease (CD) in the target tissue and peripheral blood monocytes (PBMC) or serum to introduce possible potential biomarkers.

BACKGROUND

Celiac disease (CD) is an autoimmune disease induced by gluten ingestion in genetically predisposed individuals. Despite technological progress, small intestine biopsy is still the gold standard for diagnosis of CD.

METHODS

CD data were collected from public databases (proteomics and microarray-based techniques documents). Differentially expressed genes (DEGs) in PBMC or serum as well as small intestinal biopsies from celiac patients compared to normal were collected and analyzed to introduce common individuals. Gene ontology was done to identify the involved biological terms.

RESULTS

Among 598 CD genes in biopsies and 260 genes in PBMC or serum, 32 common genes with a similar expression pattern in both sources were identified. A total of 48 biological terms were introduced which were involved in the CD via the determined DEGs. "Cytokine activity" was the most expanded one of the biological terms.

CONCLUSION

In this analysis, it was concluded that 32 potential biomarkers of CD can be assessed by complementary research to introduce effective and available biomarkers in biopsy and blood.

The Fifth Domain of Beta 2 Glycoprotein I Protects from Natural IgM Mediated Cardiac Ischaemia Reperfusion Injury

Reperfusion after a period of ischemia results in reperfusion injury (IRI) which involves activation of the inflammatory cascade. In cardiac IRI, IgM natural antibodies (NAb) play a prominent role through binding to altered neoepitopes expressed on damaged cells. Beta 2 Glycoprotein I (β2GPI) is a plasma protein that binds to neoepitopes on damaged cells including anionic phospholipids through its highly conserved Domain V. Domain I of β2GPI binds circulating IgM NAbs and may provide a link between the innate immune system, IgM NAb binding and cardiac IRI. This study was undertaken to investigate the role of Β2GPI and its Domain V in cardiac IRI using wild-type (WT), Rag-1 ^-/- and β2GPI deficient mice. Compared with control, treatment with Domain V prior to cardiac IRI prevented binding of endogenous β2GPI to post-ischemic myocardium and resulted in smaller myocardial infarction size in both WT and β2GPI deficient mice. Domain V treatment in WT mice also resulted in less neutrophil infiltration, less apoptosis and improved ejection fraction at 24 h. Rag-1 -/- antibody deficient mice reconstituted with IgM NAbs confirmed that Domain V prevented IgM NAb induced cardiac IRI. Domain V remained equally effective when delivered at the time of reperfusion which has therapeutic clinical relevance.Based upon this study Domain V may function as a universal inhibitor of IgM NAb binding in the setting of cardiac IRI, which offers promise as a new therapeutic strategy in the treatment of cardiac IRI.

Radiation-induced changes in levels of selected proteins in peripheral blood serum of breast cancer patients as a potential triage biodosimeter for large-scale radiological emergencies

The threat of a large scale radiological emergency, where thousands of people may require fast biological dosimetry for the purpose of triage, makes it necessary to search for new, high throughput biological dosimeters. The authors tested an assay based on the quantitative analysis of selected proteins in peripheral blood serum. They were particularly interested in testing proteins that are specific to irradiation of skin, as these can be used in cases of partial body exposure. Candidate proteins were identified in an earlier study with mice, where skin of the animals was exposed to different doses of radiation and global expression of serum proteins was analyzed. Eight proteins were found, the expression of which showed a consistent dose-response relationship. Human analogues of these proteins were identified, and their expression was measured in peripheral blood serum of 16 breast cancer patients undergoing external beam radiotherapy. The proteins were Apolipoprotein E; Apolipoprotein H; Complement protein 7; Prothrombinase; Pantothenate Kinase 4; Alpha-2-macroglobulin; Fetuin B and Alpha-1-Anti-Chymotrypsin. Measurements were carried out in blood samples collected prior to exposure (control), on the day after one fraction (2 Gy), on the day after five fractions (10 Gy), on the day after 10 fractions (20 Gy), and 1 mo after 23-25 fractions (total dose of 46-50 Gy). Multivariate analysis was carried out, and a multinomial logistic regression model was built. The results indicate that the combined analysis of Apolipoprotein E, Factor X, and Pantothenate Kinase 4 allows discriminating between exposure to 2 Gy and lower and between 10 Gy and higher. The discrimination is possible up to 1 mo after exposure.

Differential expression of genes and changes in glucose metabolism in the liver of liver-specific glucokinase gene knockout mice

To investigate the role of liver-specific expression of glucokinase (GCK) in the pathogenesis of hyperglycemia and to identify candidate genes involved in mechanisms of the onset and progression of maturity onset diabetes of the young, type 2 (MODY-2), we examined changes in biochemical parameters and gene expression in GCK knockout (gck(w/-)) and wild-type (gck(w/w)) mice as they aged. Fasting blood glucose levels were found to be significantly higher in the gck(w/-) mice, compared to age-matched gck(w/w) mice, at all ages (P<0.05), except at 2 weeks. GCK activity of gck(w/-) mice was about 50% of that of wild type (gck(w/w)) mice (P<0.05). Glycogen content at 4 and 40 weeks of age was lower in gck(w/-) mice compared to gck(w/w) mice. Differentially expressed genes in the livers of 2 and 26 week-old liver-specific GCK knockout (gck(w/-)) mice were identified by suppression subtractive hybridization (SSH), which resulted in the identification of phosphoenolpyruvatecarboxykinase (PEPCK, also called PCK1) and Sterol O-acyltransferase 2 (SOAT2) as candidate genes involved in pathogenesis. The expressions of PEPCK and SOAT2 along with glycogen phosphorylase (GP) and glycogen synthase (GS) were then examined in GCK knockout (gck(w/-)) and wild-type (gck(w/w)) mice at different ages. Changes in PEPCK mRNA levels were confirmed by real-time RT-PCR, while no differences in the levels of expression of SOAT2 or GS were observed in age-matched GCK knockout (gck(w/-)) and wild-type (gck(w/w)) mice. GP mRNA levels were decreased in 40-week old gck(w/-) mice compared to age-matched gck(w/w) mice. Changes in gluconeogenesis, delayed development of GCK and impaired hepatic glycogen synthesis in the liver potentially lead to the onset and progression of MODY2.

Exosomes in erythropoiesis

Multivesicular endosomes contain membrane vesicles which can be released into the extracellular environment as exosomes. This review describes the role of exosome secretion in the remodeling of the red cell plasma membrane during the last stage of erythropoietic differentiation. Herein, we propose that the exosome biogenesis involves several mechanisms of protein sorting and leads to partial or complete loss of membrane activities, in some cases in a regulated way.

IgM colocalises with complement and C reactive protein in infarcted human myocardium

AIMS

Reperfusion of ischaemic myocardium after acute myocardial infarction (AMI) can induce ischaemia/reperfusion (I/R) injury, as a result of local activation of the complement system. C reactive protein (CRP) is involved in this activation. This study analysed the potential role of IgM in complement activation in the infarcted human myocardium.

METHODS

Immunochemical analysis was carried out on heart specimens from 59 patients who died from AMI. Serial slides of frozen tissue from the infarction site were stained for IgM, complement factors C3d and C5b-9 (membrane attack complex), and CRP.

RESULTS

IgM deposits were found on the plasma membrane, cross striations, and in the cytoplasm of jeopardised cardiomyocytes in infarcts of one to five days duration. IgM depositions were remarkably similar to those of CRP and both complement factors. The relative staining intensities of IgM and CRP varied greatly among patients.

CONCLUSIONS

Similar to CRP, IgM targets complement locally to jeopardised cardiomyocytes in the human heart after AMI. Localisation patterns and relative staining intensities suggest that IgM and CRP recognise similar epitopes in the ischaemic heart, but that the relative contribution of each protein to complement activation in the ischaemic myocardium differs among patients.

Relation of preexisting anti-beta2GPI antibodies to infarct size in a rat model

BACKGROUND

Anti-beta2-glycoprotein I (beta2GPI) antibodies (a subpopulation of antiphospholipid (aPL) antibodies) are associated with a procoagulant state in humans and with enhanced atherosclerosis in experimental animal models. Moreover, the presence of high titers of aPL antibodies in relatively young patients is associated with higher incidence of subsequent myocardial infarction. Herein, we evaluated the role of preexisting high levels of aPL antibodies in determining the size of the infarct induced by permanent ligation of the left anterior descending artery (LAD) in a rat model.

METHODS AND RESULTS

A total of 11 Wistar rats were immunized and boosted with 10 microg of the phospholipid binding protein -beta2GPI (a method commonly applied for induction of aPL antibodies). Rats in the control group (n=9) were immunized and boosted with a Freund's adjuvant. Upon development of high anti-beta2GPI antibodies levels, myocardial infarction was induced by ligation of the LAD coronary artery. Rats were sacrificed 7 days later, their lymph nodes were collected for evaluation of cellular immunity to beta2GPI and their hearts were removed for assessment of infarct size and for immunohistochemical stains for iNOS and TGF-beta. beta2GPI-immunized rats exhibited high levels of aPL antibodies (mean optical density of 1.3+/-0.3) as compared with the control group (mean optical density of 0.12+/-0.03; P<.0001). Cellular immunity to beta2GPI was also pronounced as evident by an increased thymidine uptake and by increased interferon gamma secretion by the lymph node cells from beta2GPI-immunized rats. Myocardial infarct size has shown a tendency to be increased in rats induced to develop anti-beta2GPI antibodies (mean size 23+/-9%) as compared with controls (17+/-12%; P<.23). iNOS positive cells in the infarct area of beta2GPI-immunized rats were significantly increased in comparison to the control group (P<.01). Similarly, TGF-beta cell expression was significantly increased in the infarct area of the immunized rats in comparison to the control group (22.6+/-5.1 and 7+/-2.1 per 100 mononuclear inflammatory cells, respectively; P=.01).

CONCLUSION

The presence of high levels of aPL antibodies is associated with higher expression of iNOS and TGF-beta and may contribute to myocardial damage.

C-reactive protein activates complement in infarcted human myocardium

Circulating levels of C-reactive protein (CRP) constitute a cardiovascular risk marker. Immunohistochemical studies have revealed co-localization of CRP and activated complement in human infarcted myocardium suggesting CRP to enhance inflammation in ischemic myocardium by inducing local complement activation. The aim was to establish whether CRP activates complement in infarcted human myocardium and to assess the relationship between this activation and the duration of infarction. Myocardial tissue samples from 56 patients that had died from acute myocardial infarction were evaluated. Specimens were taken from infarcted as well as noninfarcted sites of the heart. CRP-mediated complement activation was assessed by immunohistochemistry and by measuring levels of complement, CRP, and CRP-complement complexes, specific markers for CRP-mediated activation, in homogenates of the heart. Infarctions of 12 hours to 5 days had significantly more extensive depositions of complement and CRP and contained significantly more CRP, activated complement, and CRP-complement complexes than infarctions that were less than 12 hours old. Levels of CRP complexes correlated significantly with CRP and complement concentrations in the infarctions, as well as with the extent of complement and CRP depositions as measured via immunohistochemistry. Specific activation products of CRP-mediated activation of complement are increased in infarcts of more than 12 hours in duration and correlate with the extent of complement depositions. Hence, CRP seems to enhance local inflammatory reactions ensuing in human myocardial infarcts of more than 12 hours duration.