Research Progress on Leucine-Rich Alpha-2 Glycoprotein 1: A Review

Nutraceutical Supplementation as a Potential Non-Drug Treatment for Fibromyalgia: Effects on Lipid Profile, Oxidative Status, and Quality of Life

Fibromyalgia (FM) is a chronic syndrome of unknown etiology, although many studies point to inflammation, oxidative stress, and altered mitochondrial metabolism as some of the cornerstones of this disease. Despite its socioeconomic importance and due to the difficulties in diagnosis, there are no effective treatments. However, the use of non-drug treatments is increasingly becoming a recommended strategy. In this context, the effects of supplementation of FM patients with an olive (poly)phenol, vitamin C, and vitamin B preparation were investigated in this work, analyzing complete blood count, biochemical, lipid, and coagulation profiles, and inflammation and oxidation status in blood samples. To gain a better understanding of the molecular mechanisms and pathways involved in the etiology of FM, a proteomic study was also performed to investigate the mechanisms of action of the supplement. Our results show that the nutraceutical lowers the lipid profile, namely cholesterol, and improves the oxidative status of patients as well as their quality of life, suggesting that this product could be beneficial in the co-treatment of FM. ClinicalTrials.gov (ID: NCT06348537).

Unveiling novel serum biomarkers in intrahepatic cholangiocarcinoma: a pilot proteomic exploration

Recent advancements in proteomics have shown promise in identifying biomarkers for various cancers. Our study is the first to compare the serum proteomes of intrahepatic cholangiocarcinoma (iCCA) with cirrhosis (CIR), primary sclerosing cholangitis (PSC), and hepatocellular carcinoma (HCC), aiming to identify a proteomic signature that can effectively distinguish among these conditions. Utilizing high-throughput mass spectrometry on serum samples, we identified 845 proteins, of which 646 were suitable for further analysis. Unique clustering patterns were observed among the five groups, with significant proteomic differences. Our key findings include: S100 calcium-binding protein A9 (S100A9) and haptoglobin (HP) were more abundant in iCCA, while intercellular adhesion molecule 2 (ICAM2) was higher in HCC. Serum amyloid A1 (SAA1) and A4 (SAA4) emerged as potential biomarkers, with SAA1 significantly different in the iCCA vs healthy controls (HC) comparison, and SAA4 in the HCC vs HC comparison. Elevated levels of vascular cell adhesion molecule 1 (VCAM-1) in HCC suggested its potential as a differentiation and diagnostic marker. Angiopoietin-1 receptor (TEK) also showed discriminatory and diagnostic potential in HCC. ELISA validation corroborated mass spectrometry findings. Our study underscores the potential of proteomic profiling in distinguishing iCCA from other liver conditions and highlights the need for further validation to establish robust diagnostic biomarkers.

Diagnostic Performance of Serum Leucine-Rich Alpha-2-Glycoprotein 1 in Pediatric Acute Appendicitis: A Prospective Validation Study

Introduction: Leucine-rich alpha-2-glycoprotein 1(LRG-1) is a human protein that has shown potential usefulness as a biomarker for diagnosing pediatric acute appendicitis (PAA). This study aims to validate the diagnostic performance of serum LRG-1 in PAA. Material and Methods: This work is a subgroup analysis from BIDIAP (BIomarkers for DIagnosing Appendicitis in Pediatrics), a prospective single-center observational cohort, to validate serum LRG-1 as a diagnostic tool in PAA. This analysis included 200 patients, divided into three groups: (1) healthy patients undergoing major outpatient surgery (n = 56), (2) patients with non-surgical abdominal pain (n = 52), and (3) patients with a confirmed diagnosis of PAA (n = 92). Patients in group 3 were divided into complicated and uncomplicated PAA. In all patients, a serum sample was obtained during recruitment, and LRG-1 concentration was determined by Enzyme-Linked ImmunoSorbent Assay (ELISA). Comparative statistical analyses were performed using the Mann-Whitney U, Kruskal-Wallis, and Fisher's exact tests. The area under the receiver operating characteristic curves (AUC) was calculated for all pertinent analyses. Results: Serum LRG-1 values, expressed as median (interquartile range) were 23,145 (18,246-27,453) ng/mL in group 1, 27,655 (21,151-38,795) ng/mL in group 2 and 40,409 (32,631-53,655) ng/mL in group 3 (p < 0.0001). Concerning the type of appendicitis, the serum LRG-1 values obtained were 38,686 (31,804-48,816) ng/mL in the uncomplicated PAA group and 51,857 (34,013-64,202) ng/mL in the complicated PAA group (p = 0.02). The area under the curve (AUC) obtained (group 2 vs. 3) was 0.75 (95% CI 0.67-0.84). For the discrimination between complicated and uncomplicated PAA, the AUC obtained was 0.66 (95% CI 0.52-0.79). Conclusions: This work establishes normative health ranges for serum LRG-1 values in the pediatric population and shows that serum LRG-1 could be a potentially helpful tool for diagnosing PAA in the future. Future prospective multicenter studies, with the parallel evaluation of urinary and salivary LRG-1, are necessary to assess the implementability of this molecule in actual clinical practice.

Precision Medicine in Inflammatory Bowel Disease: A Spotlight on Emerging Molecular Biomarkers

Inflammatory bowel diseases (IBD) remain challenging in terms of understanding their causes and in terms of diagnosing, treating, and monitoring patients. Modern diagnosis combines biomarkers, imaging, and endoscopic methods. Common biomarkers like CRP and fecal calprotectin, while invaluable tools, have limitations and are not entirely specific to IBD. The limitations of existing markers and the invasiveness of endoscopic procedures highlight the need to discover and implement new markers. With an ideal biomarker, we could predict the risk of disease development, as well as the possibility of response to a particular therapy, which would be significant in elucidating the pathogenesis of the disease. Recent research in the fields of machine learning, proteomics, epigenetics, and gut microbiota provides further insight into the pathogenesis of the disease and is also revealing new biomarkers. New markers, such as BAFF, PGE-MUM, oncostatin M, microRNA panels, αvβ6 antibody, and S100A12 from stool, are increasingly being identified, with αvβ6 antibody and oncostatin M being potentially close to being presented into clinical practice. However, the specificity of certain markers still remains problematic. Furthermore, the use of expensive and less accessible technology for detecting new markers, such as microRNAs, represents a limitation for widespread use in clinical practice. Nevertheless, the need for non-invasive, comprehensive markers is becoming increasingly important regarding the complexity of treatment and overall management of IBD.

LRG1 and SDR16C5 protein expressions differ according to HPV status in oropharyngeal squamous cell carcinoma

The increasing incidence of oropharyngeal squamous cell carcinoma (OPSCC) is primarily due to human papillomavirus, and understanding the tumor biology caused by the virus is crucial. Our goal was to investigate the proteins present in the serum of patients with OPSCC, which were not previously studied in OPSCC tissue. We examined the difference in expression of these proteins between HPV-positive and -negative tumors and their correlation with clinicopathological parameters and patient survival. The study included 157 formalin-fixed, paraffin-embedded tissue samples and clinicopathological data. Based on the protein levels in the sera of OPSCC patients, we selected 12 proteins and studied their expression in HPV-negative and HPV-positive OPSCC cell lines. LRG1, SDR16C5, PIP4K2C and MVD proteins were selected for immunohistochemical analysis in HPV-positive and -negative OPSCC tissue samples. These protein´s expression levels were compared with clinicopathological parameters and patient survival to investigate their clinical relevance. LRG1 expression was strong in HPV-negative whereas SDR16C5 expression was strong in HPV-positive tumors. Correlation was observed between LRG1, SDR16C5, and PIP4K2C expression and patient survival. High expression of PIP4K2C was found to be an independent prognostic factor for overall survival and expression correlated with HPV-positive tumor status. The data suggest the possible role of LRG1, SDR16C5 and PIP4K2C in OPSCC biology.

High serum levels of leucine-rich α-2 glycoprotein 1 (LRG-1) are associated with poor survival in patients with early breast cancer

BACKGROUND

Leucine-rich α-2 glycoprotein 1 (LRG-1) is a secreted glycoprotein that is mainly produced in the liver. Elevated levels of LRG-1 are found in a multitude of pathological conditions including eye diseases, diabetes, infections, autoimmune diseases, and cancer. In patients with early breast cancer (BC), high intratumoral LRG-1 protein expression levels are associated with reduced survival. In this study, we assessed serum levels of LRG-1 in patients with early BC and investigated its correlation with the presence of disseminated tumor cells (DTCs) in the bone marrow and survival outcomes.

METHODS

Serum LRG-1 levels of 509 BC patients were determined using ELISA and DTCs were assessed by immunocytochemistry using the pan-cytokeratin antibody A45-B/B3. We stratified LRG-1 levels according to selected clinical parameters. Using the log-rank (Mantel-Cox) test and multivariate Cox regression analysis, Kaplan-Meier survival curves and prognostic relevance were assessed.

RESULTS

Mean serum levels of LRG-1 were 29.70 ± 8.67 µg/ml. Age was positively correlated with LRG-1 expression (r = 0.19; p < 0.0001) and significantly higher LRG-1 levels were found in patients over 60 years compared to younger ones (30.49 ± 8.63 µg/ml vs. 28.85 ± 8.63 µg/ml; p = 0.011) and in postmenopausal patients compared to premenopausal patients (30.15 ± 8.34 µg/ml vs. 26.936.94 µg/ml; p = 0.002). Patients with no DTCs showed significantly elevated LRG-1 levels compared to the DTC-positive group (30.51 ± 8.69 µg/ml vs. 28.51 ± 8.54 µg/ml; p = 0.004). Overall and BC-specific survival was significantly lower in patients with high serum LRG-1 levels (above a cut-off of 33.63 µg/ml) compared to patients with lower LRG-1 levels during a mean follow-up of 8.5 years (24.8% vs. 11.1% BC-specific death; p = 0.0003; odds ratio 2.63, 95%CI: 1.56-4.36). Multivariate analyses revealed that LRG-1 is an independent prognostic marker for BC-specific survival (p = 0.001; hazard ratio 2.61).

CONCLUSIONS

This study highlights the potential of LRG-1 as an independent prognostic biomarker in patients with early BC.

LRG1 Contributes to the Pathogenesis of Multiple Kidney Diseases: A Comprehensive Review

Background

The increasing prevalence of kidney diseases has become a significant public health issue, with a global prevalence exceeding 10%. In order to accurately identify biochemical changes and treatment outcomes associated with kidney diseases, novel methods targeting specific genes have been discovered. Among these genes, leucine-rich α-2 glycoprotein 1 (LRG1) has been identified to function as a multifunctional pathogenic signaling molecule in multiple diseases, including kidney diseases. This study aims to provide a comprehensive overview of the current evidence regarding the roles of LRG1 in different types of kidney diseases.

Summary

Based on a comprehensive review, it was found that LRG1 was upregulated in the urine, serum, or renal tissues of patients or experimental animal models with multiple kidney diseases, such as diabetic nephropathy, kidney injury, IgA nephropathy, chronic kidney diseases, clear cell renal cell carcinoma, end-stage renal disease, canine leishmaniosis-induced kidney disease, kidney fibrosis, and aristolochic acid nephropathy. Mechanistically, the role of LRG1 in kidney diseases is believed to be detrimental, potentially through its regulation of various genes and signaling cascades, i.e., fibronectin 1, GPR56, vascular endothelial growth factor (VEGF), VEGFR-2, death receptor 5, GDF15, HIF-1α, SPP1, activin receptor-like kinase 1-Smad1/5/8, NLRP3-IL-1b, and transforming growth factor β pathway.

Key Messages

Further research is needed to fully comprehend the molecular mechanisms by which LRG1 contributes to the pathogenesis and pathophysiology of kidney diseases. It is anticipated that targeted treatments focusing on LRG1 will be utilized in clinical trials and implemented in clinical practice in the future.

Serum Leucine-Rich α2 Glycoprotein Could Be a Useful Biomarker to Differentiate Patients with Normal Colonic Mucosa from Those with Inflammatory Bowel Disease or Other Forms of Colitis

(1) Background: Serum leucine-rich α2 glycoprotein (LRG) has been reported as a useful biomarker for monitoring disease activity in patients with inflammatory bowel disease (IBD). We investigated whether serum LRG can differentiate patients with normal colonic mucosa from those with IBD or other forms of colitis. (2) Methods: Patients with diarrhea, abdominal pain, or bloody stools were consecutively enrolled at their initial visit to our hospital. Serum LRG and C-reactive protein were measured, and a colonoscopy and histology were performed. (3) Results: We enrolled 317 patients (181 men, 136 women; median age: 51 years). Based on the endoscopic and histological criteria, 260 patients were diagnosed with ulcerative colitis (n = 134), Crohn's disease (n = 10), infectious colitis (n = 43), diverticular colitis (n = 17), or nonspecific colitis (n = 56). The remaining 57 patients were diagnosed with normal colonic mucosa including histology. The latter group's median LRG value (9.5 µg/mL, range: 5.8-13.5) was significantly lower than that of the other 260 patients (13.6 µg/mL, range: 6.8-62.7, p < 0.0001). The optimal LRG cut-off value of <10.4 µg/mL was derived from the receiver operating characteristic (ROC) curve, showing a 91% sensitivity and 77% specificity for identifying patients with normal colonic mucosa. (4) Conclusions: serum LRG values < 10.4 µg/mL could be a useful biomarker for predicting patients with normal colonic mucosa.

Plasma leucine-rich α-2 glycoprotein 1 in ST-elevation myocardial infarction: vertical variation, correlation with T helper 17/regulatory T ratio, and predictive value on major adverse cardiovascular events

Objective

Leucine-rich α-2 glycoprotein 1 (LRG1) promotes inflammation and myocardial injury, but its clinical role in ST-elevation myocardial infarction (STEMI) is rarely disclosed. Herein, this prospective study aimed to explore the value of plasma LRG1 at different time points to predict major adverse cardiovascular event (MACE) risk in patients with STEMI.

Methods

In total, 209 patients with STEMI were enrolled for determining plasma LRG1 at admission and on day (D)1/D7/D30 after admission via enzyme-linked immunosorbent assay, as well as for determination of peripheral blood T helper 17 (Th17) cells and regulatory T (Treg) cells by flow cytometry. In addition, plasma LRG1 was obtained from 30 healthy controls at enrollment.

Results

LRG1 was increased in patients with STEMI at admission compared with healthy controls (P < 0.001). In patients with STEMI, LRG1 varied at different time points (P < 0.001), which elevated from admission to D1, and gradually declined thereafter. LRG1 at admission was positively associated with Th17 cells (P = 0.001) and Th17/Treg ratio (P = 0.014). LRG1 at admission (P = 0.013), D1 (P = 0.034), D7 (P = 0.001), and D30 (P = 0.010) were increased in patients with MACE compared with those without. LRG1 at D7 exhibited good ability to estimate MACE risk (area under curve = 0.750, 95% confidence interval = 0.641-0.858). LRG1 at admission > 60 μg/ml (P = 0.031) and D7 > 60 μg/ml (P = 0.018) were linked with increased accumulating MACE. Importantly, LRG1 at D7 > 60 μg/ml was independently correlated with increased MACE risk (hazard ratio = 5.216, P = 0.033).

Conclusion

Plasma LRG1 increases from admission to D1 and gradually declines until D30, which positively links with Th17 cells and MACE risk in patients with STEMI.

Relation between LRG1 and CD4+ T cells, cognitive impairment and neurological function in patients with acute ischemic stroke

Objective: To assess the relationship between LRG1 and CD4+ T cells, cognitive impairment and neurological function in acute ischemic stroke (AIS). Methods: Plasma LRG1 was detected by ELISA in 175 patients with AIS at baseline, day (D) 1, D7, month (M) 1 and M3. Results: LRG1 was negatively related to Th2 and Treg cells and positively linked to Th17 (all p < 0.05). LRG1 increased from baseline to D1, then decreased until M3 (p < 0.001). LRG1 at each assessment point was increased in patients with cognitive impairment or poor neurological function at M3 versus those without (all p < 0.05). Conclusion: LRG1 is linked to decreased Th2 and Tregs, increased Th17, cognitive impairment and nonideal neurological function recovery in patients with AIS.

Plasma leucine-rich α-2-glycoprotein 1 - a novel marker of diabetic kidney disease in children and adolescents with type 1 diabetes mellitus?

BACKGROUND

Glomerular endothelial dysfunction and neoangiogenesis play a significant role in the pathogenesis of diabetic kidney disease (DKD). Leucine-rich α-2 glycoprotein 1 (LRG1) is a recently discovered protein that participates in the molecular pathway of inflammation and angiogenesis. We aimed to investigate efficacy of LRG1 to predict estimated glomerular filtration rate (eGFR) decrease in children and adolescents with type 1 diabetes mellitus (T1DM).

METHODS

The study comprised 72 participants with diabetes duration for ≥ 2 years. At study initiation, LRG1, urine albumin, eGFR (cystatin C-based, and Schwartz), HbA1c, and lipid values were evaluated and diabetes-related clinical features and anthropometric measurements were collected. These results were compared with final control values after ≥ 1 year. Patients were divided into subgroups according to presence of albuminuria progression, eGFR decrease, and metabolic control parameters.

RESULTS

There was positive correlation between LRG1 level and Schwartz and cystatin C-based eGFR decline (r = 0.360, p = 0.003; r = 0.447, p = 0.001, respectively), and negative correlation between final cystatin C-based eGFR and LRG1 (p = 0.01, r = -0.345). Patients with cystatin C-based eGFR decrease > 10% had significantly higher LRG1 levels (p = 0.03), however, LRG1 was not different between albuminuria progression subgroups. A 0.282 μg/ml increase in LRG1 correlated with a 1% decrease in eGFR in simple linear regression analysis (β = 0.282, %CI 0.11-0.45, p = 0.001) and LRG1 was an independent predictor of GFR decline even in the presence of covariates.

CONCLUSIONS

Our study supports the relationship between plasma LRG1 and eGFR decline and suggests LRG1 may be an early marker of DKD progression in children with T1DM. A higher resolution version of the Graphical abstract is available as Supplementary information.

Single-cell RNA sequencing unveils Lrg1's role in cerebral ischemia‒reperfusion injury by modulating various cells

BACKGROUND AND PURPOSE

Cerebral ischemia‒reperfusion injury causes significant harm to human health and is a major contributor to stroke-related deaths worldwide. Current treatments are limited, and new, more effective prevention and treatment strategies that target multiple cell components are urgently needed. Leucine-rich alpha-2 glycoprotein 1 (Lrg1) appears to be associated with the progression of cerebral ischemia‒reperfusion injury, but the exact mechanism of it is unknown.

METHODS

Wild-type (WT) and Lrg1 knockout (Lrg1-/-) mice were used to investigate the role of Lrg1 after cerebral ischemia‒reperfusion injury. The effects of Lrg1 knockout on brain infarct volume, blood‒brain barrier permeability, and neurological score (based on 2,3,5-triphenyl tetrazolium chloride, evans blue dye, hematoxylin, and eosin staining) were assessed. Single-cell RNA sequencing (scRNA-seq), immunofluorescence, and microvascular albumin leakage tests were utilized to investigate alterations in various cell components in brain tissue after Lrg1 knockout.

RESULTS

Lrg1 expression was increased in various cell types of brain tissue after cerebral ischemia‒reperfusion injury. Lrg1 knockout reduced cerebral edema and infarct size and improved neurological function after cerebral ischemia‒reperfusion injury. Single-cell RNA sequencing analysis of WT and Lrg1-/- mouse brain tissues after cerebral ischemia‒reperfusion injury revealed that Lrg1 knockout enhances blood‒brain barrier (BBB) by upregulating claudin 11, integrin β5, protocadherin 9, and annexin A2. Lrg1 knockout also promoted an anti-inflammatory and tissue-repairing phenotype in microglia and macrophages while reducing neuron and oligodendrocyte cell death.

CONCLUSIONS

Our results has shown that Lrg1 mediates numerous pathological processes involved in cerebral ischemia‒reperfusion injury by altering the functional states of various cell types, thereby rendering it a promising therapeutic target for cerebral ischemia‒reperfusion injury.

Leucine-Rich Alpha-2-Glycoprotein as a non-invasive biomarker for pediatric acute appendicitis: a systematic review and meta-analysis

The aim of this study was to analyze the diagnostic performance of Leucine-Rich Alpha-2-Glycoprotein (LRG1) in pediatric acute appendicitis (PAA). We conducted a systematic review of the literature in the main databases of medical bibliography. Two independent reviewers selected the articles and extracted relevant data. Methodological quality was assessed using the QUADAS2 index. A synthesis of the results, standardization of the metrics and 4 random-effect meta-analyses were performed. Eight studies with data from 712 participants (305 patients with confirmed diagnosis of PAA and 407 controls) were included in this review. The random-effect meta-analysis of serum LRG1 (PAA vs control) resulted in a significant mean difference (95% CI) of 46.76 μg/mL (29.26-64.26). The random-effect meta-analysis for unadjusted urinary LRG1 (PAA vs control) resulted in a significant mean difference (95% CI) of 0.61 μg/mL (0.30-0.93). The random-effect meta-analysis (PAA vs control) for urinary LRG1 adjusted for urinary creatinine resulted in a significant mean difference (95% CI) of 0.89 g/mol (0.11-1.66).   Conlusion: Urinary LRG1 emerges as a potential non-invasive biomarker for the diagnosis of PAA. On the other hand, due to the high between-study heterogeneity, the results on serum LRG1 should be interpreted with caution. The only study that analyzed salivary LRG1 showed promising results. Further prospective studies are needed to confirm these findings. What is Known: • Pediatric acute appendicitis continues to be a pathology with a high rate of diagnostic error. • Invasive tests, although useful, are a source of stress for patients and their parents. What is New: • LRG1 emerges as a promising urinary and salivary biomarker for the noninvasive diagnosis of pediatric acute appendicitis.

Crystal structure of LRG1 and the functional significance of LRG1 glycan for LPHN2 activation

The serum glycoprotein leucine-rich ɑ-2-glycoprotein 1 (LRG1), primarily produced by hepatocytes and neutrophils, is a multifunctional protein that modulates various signaling cascades, mainly TGFβ signaling. Serum LRG1 and neutrophil-derived LRG1 have different molecular weights due to differences in glycosylation, but the impact of the differential glycan composition in LRG1 on its cellular function is largely unknown. We previously reported that LRG1 can promote both angiogenic and neurotrophic processes under hyperglycemic conditions by interacting with LPHN2. Here, we determined the crystal structure of LRG1, identifying the horseshoe-like solenoid structure of LRG1 and its four N-glycosylation sites. In addition, our biochemical and cell-biological analyses found that the deglycosylation of LRG1, particularly the removal of glycans on N325, is critical for the high-affinity binding of LRG1 to LPHN2 and thus promotes LRG1/LPHN2-mediated angiogenic and neurotrophic processes in mouse tissue explants, even under normal glucose conditions. Moreover, the intracavernous administration of deglycosylated LRG1 in a diabetic mouse model ameliorated vascular and neurological abnormalities and restored erectile function. Collectively, these data indicate a novel role of LRG1 glycans as molecular switches that can tune the range of LRG1's cellular functions, particularly the LRG1/LPHN2 signaling axis.

Predictive Value of Leucine-Rich Alpha-2 Glycoprotein 1 in Cerebrospinal Fluid for the Prognosis of Aneurysmal Subarachnoid Hemorrhage: A Prospective Study

OBJECTIVE

To determine whether leucine-rich alpha-2 glycoprotein 1 (LRG1) is a potential prognostic and severity biomarker in patients with aneurysmal subarachnoid hemorrhage (aSAH).

METHODS

This observational and prospective study included 44 patients with aSAH from Nanjing Drum Tower Hospital from June to December 2020. Concentrations of LRG1 in the cerebrospinal fluid (CSF) were determined by enzyme-linked immunosorbent assay within 24 hours after aSAH. We further determined the relationship of CSF LRG1 levels with disease severity and prognosis 3 months after aSAH.

RESULTS

Higher CSF LRG1 levels were associated with a higher Hunt-Hess grade (P < 0.05). Using univariate analysis, poor outcomes at 3 months were associated with higher World Federation of Neurological Surgeons scale grade, higher Hunt-Hess grade, higher CSF LRG1 levels, and higher Fisher grade. Logistic regression analysis revealed a significant impact of LRG1 on poor outcomes as well as after adjustment for confounding factors.

CONCLUSIONS

These findings suggest an increase in CSF LRG1 levels in patients with aSAH, which may serve as a potential biomarker of unfavorable prognosis and disease severity.

Alterations of plasma exosomal proteins and motabolies are associated with the progression of castration-resistant prostate cancer

BACKGROUND

Current diagnosis tools for prostate cancer (PCa) such as serum PSA detection and prostate biopsy cannot distinguish dormant tumors from invasive malignancies, either be used as prognosis marker for castration resistant prostate cancer (CRPC), the lethal stage of PCa patients. Exosomes have been widely investigated as promising biomarkers for various diseases. We aim to characterize the proteomic and metabolomic profile of exosomes and to evaluate their potential value for the diagnosis of PCa, especially CRPC. We also investigate the functions of some specific exosome biomarkers in the progression of CRPC.

METHODS

Integrated proteomics and metabolomics analysis were performed for plasma-derived exosomes collected from tumor-free controls (TFC), PCa and CRPC patients. Expression of specific exosomal proteins were further validated by targeted 4D-parallel reaction monitoring (PRM) mass spectrometry among the three cohorts. Tissue distribution and functional role of exosomal protein LRG1 was studied in clinical PCa tissue samples and cell line models.

RESULTS

Three potential exosomal protein markers were identified. The apolipoprotein E level in PCa samples was 1.7-fold higher than that in TFC (receiver operating characteristic value, 0.74). Similarly, the levels of exosome-derived leucine-rich alpha2-glycoprotein 1 (LRG1) and inter-alpha-trypsin inhibitor heavy chain H3 (ITIH3) in the CRPC group were 1.7 and 2.04 times, respectively, higher than those in the PCa group (ROC values, 0.84 and 0.85, respectively), indicating that LRG1 and ITIH3 could serve as predictive markers for CRPC. For metabolomic evaluation of exosomes, a series of differentially expressed metabolites were identified, and a combined metabolite panel showed ROC value of 0.94 for distinguishing PCa from TFC and 0.97 for distinguishing CRPC from PCa. Immunohistochemistry of tissue microarray showed that LRG1 protein was significantly upregulated in advanced prostate cancer and functional assay revealed that ectopic expression of LRG1 can significantly enhance the malignant phenotype of prostate cancer cells. More importantly, PCa cell derived LRG1-overexpressed exosomes remarkably promoted angiogenesis.

CONCLUSION

Integration of proteomics and metabolomics data generated proteomic and metabolic signatures of plasma exosomes that may facilitate discrimination of CRPC from PCa and TFC patients, suggesting the potential of exosomal proteins and metabolites as CRPC markers. The study also confirmed the important role of exosomal protein LRG1 in PCa malignant progression.

Serum Leucine-Rich α2 Glycoprotein: A Novel Biomarker for Transmural Inflammation in Crohn's Disease

INTRODUCTION

Leucine-rich alpha-2 glycoprotein (LRG) is a newly studied biomarker for inflammatory diseases. This study aimed to investigate whether LRG can be used for evaluating transmural activity in patients with Crohn's disease (CD).

METHODS

We performed magnetic resonance enterography (MRE) in 227 consecutive CD patients from June 2020 to August 2021. We prospectively compared MRE findings with clinical and laboratory data including LRG. MRE was evaluated using 2 validated scoring systems, and transmural inflammation was defined as having a maximum simplified magnetic resonance index of activity (sMaRIA) score of ≥4 and a 5-point classification score of ≥9, respectively.

RESULTS

The correlation between LRG and the total MRE score showed a positive correlation ( r = 0.576 for sMaRIA score, P < 0.01 and r = 0.633 for 5-point score, P < 0.01). Serum concentrations of LRG significantly increased as MRE scores increased ( P < 0.01). The area under the curve of LRG for sMaRIA score of ≥4 and 5-point score of ≥9 was 0.845 and 0.869, respectively, which was significantly higher than that of CDAI ( P < 0.01) or C-reactive protein ( P < 0.01). LRG levels of ≥14 μg/mL had a 67% sensitivity and a 90% specificity for sMaRIA score of ≥4, and 73% sensitivity and 89% specificity for 5-point score of ≥9. Patients with high LRG levels were also strongly associated with CD-related hospitalization, surgery, and clinical relapse compared to those with low LRG levels ( P < 0.01 for all).

DISCUSSION

LRG is a highly accurate serum biomarker for detecting transmural activity in CD patients. Results need to be validated in further multicenter studies.

Biomarkers in Systemic Juvenile Idiopathic Arthritis, Macrophage Activation Syndrome and Their Importance in COVID Era

Systemic juvenile idiopathic arthritis (sJIA) and its complication, macrophage activation syndrome (sJIA-MAS), are rare but sometimes very serious or even critical diseases of childhood that can occasionally be characterized by nonspecific clinical signs and symptoms at onset-such as non-remitting high fever, headache, rash, or arthralgia-and are biologically accompanied by an increase in acute-phase reactants. For a correct positive diagnosis, it is necessary to rule out bacterial or viral infections, neoplasia, and other immune-mediated inflammatory diseases. Delays in diagnosis will result in late initiation of targeted therapy. A set of biomarkers is useful to distinguish sJIA or sJIA-MAS from similar clinical entities, especially when arthritis is absent. Biomarkers should be accessible to many patients, with convenient production and acquisition prices for pediatric medical laboratories, as well as being easy to determine, having high sensitivity and specificity, and correlating with pathophysiological disease pathways. The aim of this review was to identify the newest and most powerful biomarkers and their synergistic interaction for easy and accurate recognition of sJIA and sJIA-MAS, so as to immediately guide clinicians in correct diagnosis and in predicting disease outcomes, the response to treatment, and the risk of relapses. Biomarkers constitute an exciting field of research, especially due to the heterogeneous nature of cytokine storm syndromes (CSSs) in the COVID era. They must be selected with utmost care-a fact supported by the increasingly improved genetic and pathophysiological comprehension of sJIA, but also of CSS-so that new classification systems may soon be developed to define homogeneous groups of patients, although each with a distinct disease.