Serum Clusterin Concentration and Its Glycosylation Changes as Potential New Diagnostic Markers of SARS-CoV-2 Infection and Recovery Process.

COVID-19 is an infectious disease caused by the SARS-CoV-2 virus. Glycoprotein clusterin (CLU) has many functions such as phagocyte recruitment, complement system inhibition, apoptosis inhibition, hormone and lipid transport, as well as in the immune response. The study aimed to assess the changes in CLU concentrations and the profile and degree of CLU glycosylation between patients with severe COVID-19, convalescents, and healthy subjects (control). The profile and degree of serum CLU N-glycosylation were analyzed using lectin-ELISA with specific lectins. CLU concentrations were significantly lower and relative reactivities of CLU glycans with SNA (Sambucus nigra agglutinin) were significantly higher in severe COVID-19 patients in comparison to convalescents and the control group. The relative reactivities of CLU glycans with MAA (Maackia amurensis agglutinin), together with relative reactivity with LCA (Lens culinaris agglutinin), were also significantly higher in patients with severe COVID-19 than in convalescents and the control group, but they also significantly differed between convalescents and control. The development of acute inflammation in the course of severe COVID-19 is associated with a decrease in CLU concentration, accompanied by an increase in the expression of α2,3-linked sialic acid, and core fucose. Both of these parameters can be included as useful glycomarkers differentiating patients with severe COVID-19 from convalescents and the control group, as well as convalescents and healthy subjects.

Plasma apolipoprotein concentrations and incident diabetes in subjects with prediabetes.

BACKGROUND: The identification of circulating biomarkers associated with the risk of type 2 diabetes (T2D) is useful for improving the current prevention strategies in the most at-risk patients. Here, we aimed to investigate the association of plasma apolipoprotein concentrations in prediabetes subjects with the incidence of new-onset T2D during follow-up. METHODS: In the IT-DIAB prospective study, 307 participants with impaired fasting glucose levels (fasting plasma glucose [FPG]: 110-125 mg/dL) were followed yearly for 5 years. The onset of T2D was defined as a first FPG value ≥ 126 mg/dL during follow-up. Apolipoprotein (apo)A-I, A-II, A-IV, B100, C-I, C-II, C-III, C-IV, D, E, F, H, J, L1, M, and (a) plasma concentrations were determined by mass spectrometry. Correlations between apolipoproteins and metabolic parameters at baseline were assessed by Spearman's coefficients. Kaplan-Meier curves were drawn using a ternary approach based on terciles and incident T2D. The association between plasma apolipoproteins concentrations and the incidence of T2D was determined using Cox proportional-hazards models. RESULTS: During a median follow-up of 5-year, 115 participants (37.5%) developed T2D. After adjustment for age, sex, body mass index, FPG, HbA1c, and statin use, the plasma levels of apoC-I, apoC-II, apoC-III, apoE, apoF, apoH, apoJ, and apoL1 were positively associated with a high risk for T2D. After further adjustment for plasma triglycerides, only apoE (1 SD natural-log-transformed hazard ratio: 1.28 [95% confidence interval: 1.06; 1.54]; p = 0.010), apoF (1.22 [1.01; 1.48]; p = 0.037), apoJ (1.24 [1.03; 1.49]; p = 0.024), and apoL1 (1.26 [1.05; 1.52]; p = 0.014) remained significantly associated with the onset of T2D. Kaplan-Meier survival curves also showed that the lower third of plasma apoE levels (< 5.97 mg/dL) was significantly associated with a lower risk of conversion to T2D (log-rank test, p = 0.002) compared to the middle and upper thirds. CONCLUSIONS: The plasma apoE levels are positively associated with the risk of T2D in prediabetes subjects, independently of traditional risk factors. The possible associations of apoF, apoJ, and apoL1 with T2D risk also pave the way for further investigations. Trial registration This trial was registered at clinicaltrials.gov as NCT01218061 and NCT01432509.

Glycosylated apolipoprotein J in cardiac ischaemia: molecular processing and circulating levels in patients with acute ischaemic events.

AIM: Using proteomics, we previously found that serum levels of glycosylated (Glyc) forms of apolipoprotein J (ApoJ), a cytoprotective and anti-oxidant protein, decrease in the early phase of acute myocardial infarction (AMI). We aimed to investigate: (i) ApoJ-Glyc intracellular distribution and secretion during ischaemia; (ii) the early changes in circulating ApoJ-Glyc during AMI; and (iii) associations between ApoJ-Glyc and residual ischaemic risk post-AMI. METHODS AND RESULTS: Glycosylated apolipoprotein J was investigated in: (i) cells from different organ/tissue origin; (ii) a pig model of AMI; (iii) de novo AMI patients (n = 38) at admission within the first 6 h of chest pain onset and without troponin T elevation at presentation (early AMI); (iv) ST-elevation myocardial infarction patients (n = 212) who were followed up for 6 months; and (v) a control group without any overt cardiovascular disease (n = 144). Inducing simulated ischaemia in isolated cardiac cells resulted in an increased intracellular accumulation of non-glycosylated ApoJ forms. A significant decrease in ApoJ-Glyc circulating levels was seen 15 min after ischaemia onset in pigs. Glycosylated apolipoprotein J levels showed a 45% decrease in early AMI patients compared with non-ischaemic patients (P < 0.0001), discriminating the presence of the ischaemic event (area under the curve: 0.934; P < 0.0001). ST-elevation myocardial infarction patients with lower ApoJ-Glyc levels at admission showed a higher rate of recurrent ischaemic events and mortality after 6-month follow-up (P = 0.008). CONCLUSIONS: These results indicate that ischaemia induces an intracellular accumulation of non-glycosylated ApoJ and a reduction in ApoJ-Glyc secretion. Glycosylated apolipoprotein J circulating levels are reduced very early after ischaemia onset. Its continuous decrease indicates a worsening in the evolution of the cardiac event, likely identifying patients with sustained ischaemia after AMI.

Serum Clusterin Level Could Reflect the Current Activity of Antineutrophil Cytoplasmic Antibody-Associated Vasculitis.

PURPOSE: We investigated whether serum clusterin levels could reflect the current antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV)-specific indices. MATERIALS AND METHODS: Fifty-seven patients with AAV and 40 healthy controls were included in this study. AAV-specific indices included the Short-Form 36-Item Health Survey Physical and Mental Component Summaries (SF-36 PCS and MCS) scores, Birmingham vasculitis activity score (BVAS), five-factor score (FFS), and vasculitis damage index. Clinical and laboratory data and AAV-specific indices were obtained at blood collection. The highest tertile of BVAS (≥16) was defined as high activity of AAV. RESULTS: The median age of AAV patients was 64.0 years and 19 patients were male. SF-36 PCS score (r=0.328), SF-36 MCS score (r=0.289), BVAS (r=-0.404), erythrocyte sedimentation rate (r=-0.336), and C-reactive protein levels (r=-0.421) were significantly correlated with serum clusterin levels. In the multivariable linear regression analysis using AAV-specific indices and serum clusterin levels, both FFS (ß=0.412) and serum clusterin levels (ß=-0.250) were significantly associated with BVAS. When the optimal serum clusterin cut-off level for high activity of AAV was identified as 130.45 µg/mL, patients with serum clusterin level ≤130.45 µg/mL had a significantly higher risk for high activity of AAV than did those without (relative risk 7.194). Patients with AAV exhibited significantly lower serum clusterin levels than did healthy controls (168.2 µg/mL vs. 230.5 µg/mL). CONCLUSION: Serum clusterin levels could reflect the current disease activity in patients with AAV.

Serum Apo J as a potential marker of conversion from mild cognitive impairment to dementia.

BACKGROUND: Apolipoprotein J (ApoJ) is present in both plasma and tissues, including brain. Growing evidence suggest that this protein may play an early role on the development of the two most common forms of dementia, Alzheimer's disease (AD) and vascular dementia (VD). OBJECTIVE: To evaluate whether serum ApoJ levels might be able to predict the progression to AD, VD, or mixed dementia (AD&VD) in individuals with mild cognitive impairment (MCI). METHODS: Serum ApoJ was measured in 196 MCI subjects (aged ≥60 years) with a median follow up of 2.9 years. RESULTS: One hundred thirty-two of the enrolled MCI subjects converted to dementia. Among these, 45% developed AD, 33% mixed dementia, 13% VD (VD), and 9% other forms of dementia. A significant trend toward a progressive reduction in the incidence of dementia, regardless of the type, from tertile I (83.1%), to tertile II (63.1%), to tertile III (56.1%) was observed (p = 0.003). After adjustment for potential confounders, a twofold increase in the risk of conversion to dementia was found in subjects belonging to tertile I of Apo J compared with tertile III; the risk increased after two years of follow up, while no differences emerged within the first 2 years. CONCLUSIONS: Our results suggest that in MCI subjects, low APOJ levels may be associated with increased risk of developing dementia.

Clusterin serum levels are elevated in patients with early rheumatoid arthritis and predict disease activity and treatment response.

Clusterin (CLU) is a molecular chaperone that participates in a variety of biological processes. Recent studies indicate its possible involvement in the development of bone erosions and autoimmunity. The aim of this study was to investigate its serum concentrations in patients with early rheumatoid arthritis (RA) and to explore their potential relationship with disease activity and treatment response. Serum levels of CLU were measured in 52 patients before and 3 months after the initiation of treatment and in 52 healthy individuals. CLU levels at baseline were significantly increased in patients with early RA compared with healthy subjects (p < 0.0001). After 3 months of treatment, the levels of CLU decreased and reached concentrations comparable to those in controls. Even though there was no relationship between CLU levels and disease activity at baseline, CLU levels positively correlated with disease activity at months 3, 6 and 12 after treatment initiation. Using ROC analysis, lower CLU baseline levels predicted achieving the therapeutic target of low disease activity and remission at months 3, 6 and 12. In summary, we found increased serum concentrations of clusterin in treatment-naïve patients with early rheumatoid arthritis, and we suggest clusterin as a predictive biomarker of disease activity and treatment response.

Serum complement proteomics reveal biomarkers for hypertension disorder of pregnancy and the potential role of Clusterin.

INTRODUCTION: Hypertension disorder of pregnancy (HDP) is one of the leading causes of maternal and foetal illness. The aim of the current study was to identify and verify novel serum markers for HDP. METHODS: A label-free LC-MS/MS method was used to establish the serum proteomic profiles of 12 pre-HDP (before clinical diagnosis of HDP) pregnancies and verify prioritized candidates in the verification set of 48 pre-HDP pregnancies. These biomarkers were revalidated by ELISA in an independent cohort of 88 pre-HDP pregnancies. Subsequently, the candidate biomarkers were histologically analysed by immunohistochemistry, and function was evaluated in TEV-1 cells. RESULTS: We identified 33 proteins with significantly increased abundance and 14 with decreased abundance (peptide FDR ≤ 1%, P < 0.05). Complement was one of the top enriched components in the pre-HDP group compared with the control group. Three complement factors (CLU, CFHR5, and CRP) were significantly increased in the three sets, of which CLU was a critical factor for the development of HDP (OR = 1.22, P < 0.001). When these three factors and body weight were combined, the AUC was 0.74, with a sensitivity of 0.67 and specificity of 0.68 for HDP prediction compared with normal pregnancy. In addition, inflammation-induced CLU could inhibit the invasion of TEV-1 cells. CONCLUSIONS: Complement proteins may play an essential role in the occurrence of HDP by acting on trophoblast cells. CLU may be a high-risk factor for HDP, and the models combining candidates show reasonable screening efficiency of HDP in the first half of pregnancy.

Circulating IL-6, clusterin and irisin in obese subjects with different grades of obesity: association with insulin resistance and sexual dimorphism.

OBJECTIVE: There are discrepancies about the relationship of IL-6, clusterin and irisin with obesity and obesity associated insulin resistance and also about their sexual dimorphism. This study aimed at evaluating the circulating levels of IL-6, clusterin and irisin in obese subjects of both sexes who had different grades of obesity and examining their sexual dimorphism and their association with insulin resistance. METHODS: This study included 176 non-diabetic subjects of both sexes who were classified according to their sex into two groups; the male and the female groups. The male group (88 men) was classified according to BMI into; group 1 (22 lean men), group 2 (22 class I obese men), group 3 (22 class II obese men) and group 4 (22 class III obese men). The female group (88 women) was classified according to BMI exactly as the male group. Metabolic parameters, IL-6, clusterin, and irisin levels were measured. Data were analyzed by ANOVA test, post hoc Tukey's test and independent t-test. Pearson correlation was used to assess the association between variables. RESULTS: In obese subjects of both sexes, circulating IL-6, clusterin and irisin levels were significantly elevated and positively correlated with HOMA-IR. Obese males showed significantly higher HOMA-IR, IL-6, clusterin and irisin levels than obese females. CONCLUSION: Obesity in both sexes, especially in males was associated with high levels of IL-6, clusterin and irisin and worsened the metabolic pattern. Circulating IL-6, clusterin and irisin may represent possible therapeutic targets for insulin resistance in obese subjects.

Circulating IL-6, clusterin and irisin in obese subjects with different grades of obesity: association with insulin resistance and sexual dimorphism

ABSTRACT Objective: There are discrepancies about the relationship of IL-6, clusterin and irisin with obesity and obesity associated insulin resistance and also about their sexual dimorphism. This study aimed at evaluating the circulating levels of IL-6, clusterin and irisin in obese subjects of both sexes who had different grades of obesity and examining their sexual dimorphism and their association with insulin resistance. Subjects and methods: This study included 176 non-diabetic subjects of both sexes who were classified according to their sex into two groups; the male and the female groups. The male group (88 men) was classified according to BMI into; group 1 (22 lean men), group 2 (22 class I obese men), group 3 (22 class II obese men) and group 4 (22 class III obese men). The female group (88 women) was classified according to BMI exactly as the male group. Metabolic parameters, IL-6, clusterin, and irisin levels were measured. Data were analyzed by ANOVA test, post hoc Tukey's test and independent t-test. Pearson correlation was used to assess the association between variables. Results: In obese subjects of both sexes, circulating IL-6, clusterin and irisin levels were significantly elevated and positively correlated with HOMA-IR. Obese males showed significantly higher HOMA-IR, IL-6, clusterin and irisin levels than obese females. Conclusion: Obesity in both sexes, especially in males was associated with high levels of IL-6, clusterin and irisin and worsened the metabolic pattern. Circulating IL-6, clusterin and irisin may represent possible therapeutic targets for insulin resistance in obese subjects.

Clusterin and Its Role in Insulin Resistance and the Cardiometabolic Syndrome.

The cardiometabolic syndrome involves a clustering of metabolic and cardiovascular factors which increase the risk of patients developing both Type 2 Diabetes Mellitus and cardio/cerebrovascular disease. Although the mechanistic underpinnings of this link remain uncertain, key factors include insulin resistance, excess visceral adiposity, atherogenic dyslipidemia, and endothelial dysfunction. Of these, a state of resistance to insulin action in overweight/obese patients appears to be central to the pathophysiologic process. Given the increasing prevalence of obesity-related Type 2 Diabetes, coupled with the fact that cardiovascular disease is the number one cause of mortality in this patient population, a more thorough understanding of the cardiometabolic syndrome and potential options to mitigate its risk is imperative. Inherent in the pathogenesis of insulin resistance is an underlying state of chronic inflammation, at least partly in response to excess adiposity. Within obese adipose tissue, an immunomodulatory shift occurs, involving a preponderance of pro-inflammatory immune cells and cytokines/adipokines, along with antigen presentation by adipocytes. Therefore, various adipokines differentially expressed by obese adipocytes may have a significant effect on cardiometabolism. Clusterin is a molecular chaperone that is widely produced by many tissues throughout the body, but is also preferentially overexpressed by obese compared lean adipocytes and relates strongly to multiple components of the cardiometabolic syndrome. Herein, we summarize the known and potential roles of circulating and adipocyte-specific clusterin in cardiometabolism and discuss potential further investigations to determine if clusterin is a viable target to attenuate both metabolic and cardiovascular disease.

Circulating levels of clusterin and complement factor H in patients with obstructive sleep apnea.

Aim: Obstructive sleep apnea (OSA) activates the complement system; however, the levels of membrane attack complex (MAC) are unaltered suggesting regulatory mechanisms. Our aim was to investigate complement factor H (CFH) and clusterin, two important complement regulators in OSA. Materials & methods: We analyzed clusterin and CFH levels in plasma of 86 patients with OSA and 33 control subjects. Results: There was no difference in CFH levels between patients (1099.4/784.6-1570.5/µg/ml) and controls (1051.4/652.0-1615.1/µg/ml, p = 0.72). Clusterin levels were higher in patients with OSA (309.7/217.2-763.2/µg/ml vs 276.1/131.0-424.3/µg/ml, p = 0.048) with a trend for a positive correlation with disease severity (p = 0.073). Conclusion: Increase in clusterin levels may be protective in OSA by blocking the MAC formation.

Serum Levels of Clusterin, PKR, and RAGE Correlate with Amyloid Burden in Alzheimer's Disease.

BACKGROUND: Alzheimer's disease (AD) is the most common form of dementia and biomarkers are essential to help in the diagnosis of this disease. Image techniques and cerebrospinal fluid (CSF) biomarkers are limited in their use because they are expensive or invasive. Thus, the search for blood-borne biomarkers is becoming central to the medical community. OBJECTIVE: The main objective of this study is the evaluation of three serum proteins as potential biomarkers in AD patients. METHODS: We recruited 27 healthy controls, 19 mild cognitive impairment patients, and 17 AD patients. Using the recent A/T/N classification we split our population into two groups (AD and control). We used ELISA kits to determine Aß42, tau, and p-tau in CSF and clusterin, PKR, and RAGE in serum. RESULTS: The levels of serum clusterin, PKR, and RAGE were statistically different in the AD group compared to controls. These proteins showed a statistically significant correlation with CSF Aß42. So, they were selected to generate an AD detection model showing an AUC-ROC of 0.971 (CI 95%, 0.931-0.998). CONCLUSION: The developed model based on serum biomarkers and other co-variates could reflect the AD core pathology. So far, not one single blood-biomarker has been described, with effectiveness offering high sensitivity and specificity. We propose that the complexity of AD pathology could be reflected in a set of biomarkers also including clinical features of the patients.

Evaluation of aqueous humor and serum clusterin levels in patients with glaucoma.

BACKGROUND: To compare the aqueous humor (AH) and the serum clusterin levels of patients with pseudoexfoliation syndrome (PEX), pseudoexfoliation glaucoma (PEXG), and primary open-angle glaucoma (POAG) with each other and with an age- and sex-matched control group. METHODS: This prospective, cross-sectionalstudy evaluated 92 eyes from 92 adult cases of uncomplicated phacoemulsification and posterior chamber intraocular lens (IOL) implantation. The cases were divided into PEX, PEXG, POAG, and control groups. Serum samples were taken from the antecubital vein just before the surgery, and the AH samples were aspirated at the beginning of the surgery. Kruskal-Wallis H, One-way ANOVA, Mann-Whitney U with Bonferroni correction and Chi-Square tests were used for statistical analysis. RESULTS: The serum clusterin levels were the highest in the PEXG group, but no statistically significant differences were observed between the groups (p=0.633). The mean AH clusterin levels were 286.79±29.64 µg/mL in the PEXG group, 263.92±31.70 µg/mL in the PEX group, 272.59±49.71 µg/mL in the POAG group, and 193.50±62.38 µg/mL in the control group (p< 0.001). This came out to be 1.48 times increase for the PEXG group, 1.36 for the PEX group, and 1.41 for the POAG group when compared with the control subjects. CONCLUSIONS: A higher level of clusterin in the anterior chamber was found to be associated with PEX and PEXG. In addition, a high level of anterior chamber clusterin in POAG, which is a new finding, showed that this molecule might be important not only in pseudoexfoliation, but also other types of glaucoma like POAG.

Systematic Quantification of Neurotrophic Adipokines RBP4, PEDF, and Clusterin in Human Cerebrospinal Fluid and Serum.

CONTEXT: Data on the presence/quantification of the neurotrophic adipokines retinol-binding protein-4 (RBP4), clusterin, and pigment epithelium-derived factor (PEDF) in human cerebrospinal fluid (CSF) are scarce and migration of these adipokines across of the blood-brain barrier (BBB) is uncertain. OBJECTIVE: This work aimed to quantify RBP4, PEDF, and clusterin in paired serum and CSF samples of patients undergoing neurological evaluation. METHODS: A total of 268 patients (109 male, 159 female) were included. Adipokine serum and CSF concentrations were measured by enzyme-linked immunosorbent assay in duplicate. RESULTS: RBP4 was abundant in serum (mean, 31.9 ±â€…24.2 µg/mL). The serum concentrations were approximately 145 times higher than in CSF (CSF to serum RBP4 ratio, 8.2 ±â€…4.3 × 10-3). PEDF was detectable in serum (mean, 30.2 ±â€…11.7 µg/mL) and concentrations were approximately 25 times higher than in CSF (CSF to serum PEDF ratio, 42.3 ±â€…15.6 × 10-3). Clusterin serum concentrations were abundant with mean levels of 346.0 ±â€…114.6 µg/mL, which were approximately 40 times higher than CSF levels (CSF to serum clusterin ratio, 29.6 ±â€…23.4 × 10-3). RBP4 and PEDF serum levels correlated positively with CSF levels, which were increased in overweight/obese patients and in type 2 diabetic patients. The CSF concentrations of all 3 adipokines increased with BBB dysfunction. RBP4 in CSF correlated positively with inflammatory parameters. In detail, only RBP4 showed the kinetics and associations that are mandatory for a putative mediator of the fat-brain axis. CONCLUSION: RBP4, PEDF, and clusterin are permeable to the BBB and increase with the measure of BBB dysfunction. RBP4 represents an inflammatory neurotrophic adipokine and is a promising mediator of the fat-brain axis.

O-glycosylated clusterin as a sensitive marker for diagnosing early stages of prostate cancer.

BACKGROUND: Prostate-specific antigen (PSA) has been the most popular diagnostic marker for prostate cancer. The frequent occurrence of low PSA values (<10 ng/ml) in patients with highly suspicious prostate cancer, however, has undermined the accuracy of clinical examinations. The aim of this study was to develop a better resolution for diagnosing prostate cancer to overcome the disadvantage of PSA. METHODS: We focused on the glycosylation status of patients' serum proteins and conducted comprehensive lectin microarray analyses to characterize N- and O-glycans using sera from prostate cancer and benign prostatic diseases. Next, we retrieved candidate serum proteins with characteristic glycan structures using lectin-immobilized beads and identified them by quantitative mass spectrometry using a technique referred to as isobaric tag for relative and absolute quantitation (iTRAQ) labeling. Finally, we constructed a new assay to quantify a candidate glycoprotein with the newly identified glycans. RESULTS: Lectin microarray analyses revealed that sera from patients with prostate cancer had a higher affinity for Jacalin, Amaranthus caudatus (ACA) lectin, and Maclura pomifera (MPA) lectin, compared with that from patients with benign prostatic diseases and normal subjects, suggesting that O-glycosylated proteins are more abundant in sera from patients with prostate cancer. Then, serum glycoproteins preferentially adsorbed onto Jacalin-Agarose as well as biotin-ACA/and biotin-MPA/streptavidin-immobilized magnetic beads were isolated, labeled with iTRAQ, and identified using quantitative mass spectrometry. It was found that the ACA- and MPA-recognizable clusterin was more enriched in patients' sera from prostate cancer compared with those from benign prostatic diseases. Following this discovery, we constructed a Luminex-based assay to quantify O-glycosylated clusterin, in which total serum clusterin was first captured on anti-clusterin antibody-immobilized beads, and then clusterin-associated O-glycans were determined by the pair of biotin-MPA and streptavidin-phycoerythrin. When PSA values registered less than 10 ng/ml, the corresponding serum level of MPA-recognized clusterin determined by this assay was beneficial for distinguishing the patients with prostate cancer from the patients with benign prostatic disease. CONCLUSION: For PSA values that measure less than 10 ng/ml, the serum O-glycosylated clusterin level can be a complementary indicator for the malignancy of prostate cancer.

Urinary clusterin and cystatin B as biomarkers of tubular injury in dogs following envenomation by the European adder.

Diagnosing acute kidney injury remains a challenge since the established renal biomarkers, serum creatinine (sCr) and symmetric dimethylarginine (SDMA) reflect glomerular function and not tubular injury. Sensitive tubular markers such as urinary clusterin (uClust) and cystatin B (uCysB) have been proposed to detect AKI at an earlier stage. Since envenomation by the European adder (Vipera berus berus) could serve as a spontaneous disease model of AKI we investigated these new biomarkers in affected dogs. Concentrations of uClust and uCysB as well as sCr and SDMA were analyzed retrospectively in stored samples from 26 dogs with snake envenomation and 13 healthy controls. Higher concentrations of uClust (P < 0.012) and uCysB (P < 0.001) were observed in the snake-envenomed group. Normalization of uClust and uCysB to urinary creatinine did not alter the results. No differences were observed in sCr and SDMA between the snake-envenomed group and the healthy control group. Spearman rank correlation analysis revealed a strong association of uClust with uCysB in the snake-envenomed dogs (r = 0.75 P < 0.001) but not in the healthy controls. The high percentage of snake-envenomed dogs with increased uClust and uCysB concentrations in the absence of increased sCr and SDMA suggests renal tubular injury in the affected dogs. Larger prospective case-controlled studies are warranted to evaluate the clinical utility and prognostic value of these biomarkers.

Clinical importance of serum secreted clusterin in predicting invasive breast cancer and treatment responses.

Enhanced serum secreted clusterin (sCLU) protein was associated with progression, poor prognosis and chemotherapy sensitivity evaluation in malignant patients. However, the clinical significance of serum sCLU protein levels in patients with invasive breast cancer (IBC) is unknown. In this study, the serum sCLU protein in 2648 patients with IBC was detected. The diagnostic value and treatment responses of serum sCLU protein in patients with IBC were also performed. The results showed that the serum sCLU protein level was significantly higher in IBC patients compared to the healthy controls (P < 0.0001), and strongly correlated with higher clinical tumor stage (P < 0.001), lymph node metastasis (P < 0.001), shorter overall survival (OS) (P = 0.032) and disease-free survival (DFS) (P = 0.029), respectively. Using the cutoff value of 18.46 µg/mL, the sensitivity and specificity were 86.26% and 73.46% to separate IBC patients from noncancerous and healthy controls. The postoperative patients showed lower serum sCLU levels compared to the preoperative patients (P = 0.003). The chemoresistant patients showed higher serum sCLU levels compared to the chemosensitive patients (P < 0.001). These data indicated that serum sCLU levels are effective indicators for diagnosis and chemotherapy sensitivity evaluation in patients with IBC.

Serum Clusterin: A Potential Marker for Assessing the Clinical Severity and Short-Term Prognosis of Hepatitis B Virus-Related Acute-on-Chronic Liver Failure.

BACKGROUND: Acute-on-chronic liver failure (ACLF) is a clinical syndrome characterized by acute deterioration of liver function and high short-term mortality. Clusterin, with biological functions similar to small heat shock proteins, can protect cells from apoptosis induced by various stressors. The aim of this study was to detect the level of serum clusterin in hepatitis B virus- (HBV-) related ACLF and to assess the predictive value of clusterin for the short-term prognosis of HBV-ACLF. METHODS: We detected serum clusterin by ELISA in 108 HBV-ACLF patients, 63 HBV-non-ACLF patients, and 44 normal controls. RESULTS: Serum clusterin was markedly lower in HBV-ACLF patients (median, 51.09 µg/mL) than in HBV-non-ACLF patients (median, 188.56 µg/mL) and normal controls (median, 213.45 µg/mL; all P < 0.05). Nonsurviving HBV-ACLF patients who died within 90 days had much lower clusterin levels than did surviving patients, especially those who died within 28 days (nonsurvival group vs. survival group: 39.82 ± 19.34 vs. 72.26 ± 43.52, P < 0.001; survival time ≤ 28 vs. survival time > 28: median 28.39 vs. 43.22, P = 0.013). The results showed that for identifying HBV-ACLF, the sensitivity of clusterin (93.7%) was similar to the sensitivities of the international normalized ratio (INR; 94.4%) and total bilirubin (TBIL; 94.8%), but its specificity (90.7%) was higher than that of prothrombin activity (PTA; 65.8%) and TBIL (69.8%) and was similar to INR (88.9%). As the concentration of clusterin increased, the mortality of HBV-ACLF patients decreased significantly from 59.3% to 7.0%. Clusterin had better ability for predicting the prognosis of HBV-ACLF patients than did the model for end-stage liver disease (MELD) score and the chronic liver failure consortium (CLIF-C) ACLF score (MELD vs. clusterin: P = 0.012; CLIF-C ACLF vs. clusterin: P = 0.031). CONCLUSION: Serum clusterin is a potential biomarker for HBV-ACLF which can be used to assess clinical severity and the short-term prognosis of patients with this disease and may help clinicians identify HBV-ACLF with greater specificity and improved prognostic accuracy than existing prognostic markers.

Decreased circulating clusterin reflects severe liver complications after hepatoportoenterostomy of biliary atresia.

This study aimed to determine whether circulating levels of clusterin (CLU), an extracellular chaperone implicated in cholestatic and fibrotic processes, are associated with clinical parameters of post-operative BA patients and could serve as a BA biomarker. Ninety-six BA patients and 56 healthy controls were recruited. Circulating CLU levels were measured using enzyme-linked immunosorbent assay. Circulating CLU levels were significantly reduced in BA patients - especially those with worse outcomes including jaundice, severe liver fibrosis, and late-stage of hepatic dysfunction. Multivariate linear regression analysis revealed that circulating CLU levels were negatively associated with outcome parameters indicating jaundice status, degree of fibrosis, and liver dysfunction, but positively correlated with serum albumin and platelet number of BA patients. Lower circulating CLU levels were considerably associated with poor survival of post-operative BA patients. Receiver-operating characteristic curve analysis demonstrated a diagnostic value of circulating CLU as a non-invasive indicator for poor outcomes of BA patients (AUC = 0.85), with a sensitivity of 81.5% and a specificity of 73.5%. All findings indicate that reduced circulating CLU might reflect poor outcomes of BA patients and have potential as a novel biomarker for the disease severity following Kasai-operation.

Glycosylation of Serum Clusterin in Wild-Type Transthyretin-Associated (ATTRwt) Amyloidosis: A Study of Disease-Associated Compositional Features Using Mass Spectrometry Analyses.

Wild-type transthyretin-associated (ATTRwt) amyloidosis is an age-related disease that causes heart failure in older adults. This disease frequently features cardiac amyloid fibril deposits that originate from dissociation of the tetrameric protein, transthyretin (TTR). Unlike hereditary TTR (ATTRm) amyloidosis, where amino acid replacements destabilize the native protein, in ATTRwt amyloidosis, amyloid-forming TTR lacks protein sequence alterations. The initiating cause of fibril formation in ATTRwt amyloidosis is unclear, and thus, it seems plausible that other factors are involved in TTR misfolding and unregulated accumulation of wild-type TTR fibrils. We believe that clusterin (CLU, UniProtKB P10909), a plasma circulating glycoprotein, plays a role in the pathobiology of ATTRwt amyloidosis. Previously, we have suggested a role for CLU in ATTRwt amyloidosis based on our studies showing that (1) CLU codeposits with non-native TTR in amyloid fibrils from ATTRwt cardiac tissue, (2) CLU interacts only with non-native (monomeric and aggregated) forms of TTR, and (3) CLU serum levels in patients with ATTRwt are significantly lower compared to healthy controls. In the present study, we provide comprehensive detail of compositional findings from mass spectrometry analyses of amino acid and glycan content of CLU purified from ATTRwt and control sera. The characterization of oligosaccharide content in serum CLU derived from patients with ATTRwt amyloidosis is novel data. Moreover, results comparing CLU oligosaccharide variations between patient and healthy controls are original and provide further evidence for the role of CLU in ATTRwt pathobiology, possibly linked to disease-specific structural features that limit the chaperoning capacity of CLU.