A dual-label time-resolved fluorescence immunoassay for the simultaneous determination of cystatin C and β2-microglobulin in urine

A new method for screening acute/chronic lymphocytic leukemia: dual-label time-resolved fluorescence immunoassay

Background

Lymphocytic leukemia (LL) is a primary malignant tumor of hematopoietic tissue, which seriously affects the health of children and the elderly. The study aims to establish a new detection method for screening acute/chronic LL using time-resolved fluorescence immunoassay (TRFIA) via quantitative detection of S100 calcium binding protein A8 (S100A8) and leucine-rich alpha-2-glycoprotein 1 (LRG1) in serum.

Methods

Here a sandwich TRFIA was optimized and established: Anti-S100A8/LRG1 caputre antibodies immobilized on 96-well plates captured S100A8/LRG1, and then banded together with the anti-S100A8/LRG1 detection antibodies labeled with Europium(III) (Eu³⁺)/samarium(III) (Sm³⁺) chelates. Finally time resolved fluorometry measured the fluorescence intensity.

Results

The sensitivity of S100A8 was 1.15 ng/mL(LogY = 3.4027 + 0.4091 × LogX, R² = 0.9828, P < 0.001, dynamic range: 2.1–10,000 ng/mL), and 3.2 ng/mL for LRG1 (LogY = 3.3009 + 0.4082 × LogX, R² = 0.9748, P < 0.001, dynamic range: 4.0–10,000 ng/mL). The intra-assay and inter-assay CVs were low, ranging from 5.75% to 8.23% for S100A8 and 5.30% to 9.45% for LRG1 with high specificity and affinity in serum samples. Bland–Altman plots indicated TRFIA and ELISA kits have good agreement in clinical serum samples. Additionally, the cutoff values for S100A8 and LRG1 were 1849.18 ng/mL and 588.08 ng/mL, respectively.

Conclusion

The present TRFIA method could be used for the quantitative detection of S100A8 and LRG1 in serum, and it has high sensitivity, accuracy and specificity. Clinically, this TRFIA method could be suitable for screening of LL via the quantitative detection of S100A8 and LRG1.

Lifting the Veil: Characteristics, Clinical Significance, and Application of β-2-Microglobulin as Biomarkers and Its Detection with Biosensors

Because β-2-microglobulin (β₂M) is a surface protein that is present on most nucleated cells, it plays a key role in the human immune system and the kidney glomeruli to regulate homeostasis. The primary clinical significance of β₂M is in dialysis-related amyloidosis, a complication of end-stage renal disease caused by a gradual accumulation of β₂M in the blood. Therefore, the function of β₂M in kidney-related diseases has been extensively studied to evaluate its glomerular and tubular functions. Because increased β₂M shedding due to rapid cell turnover may indicate other underlying medical conditions, the possibility to use β₂M as a versatile biomarker rose in prominence across multiple disciplines for various applications. Therefore, this work has reviewed the recent use of β₂M to detect various diseases and its progress as a biomarker. While the use of state-of-the-art β₂M detection requires sophisticated tools, high maintenance, and labor cost, this work also has reported the use of biosensor to quantify β₂M over the past decade. It is hoped that a portable and highly efficient β₂M biosensor device will soon be incorporated in point-of-care testing to provide safe, rapid, and reliable test results.

Huoxue Qianyang Qutan Recipe Protects against Early Renal Damage Induced by Obesity-Related Hypertension via the SIRT1/NF-κB/IL-6 Pathway: Integrating Network Pharmacology and Experimental Validation-Based Strategy

Obesity is recognized as not only a major contributing factor to cardiovascular diseases but also an independent risk factor for end-stage renal disease. Previous studies have found that Huoxue Qianyang Qutan Recipe (HQQR) could reduce urinary microalbumin in patients with obesity-related hypertension (OBH). However, the renal protective activity of HQQR in OBH and its molecular targets involved remains ambiguous. In this work, we investigate the mechanism of HQQR against OBH-induced early renal damage using integrating network pharmacology and experimental validation-based strategy. First, via network pharmacology, IL-6 is identified as one of the key targets of HQQR against early renal damage in hypertension, and inhibition of inflammation is a crucial process. Second, in in vivo experiments, HQQR can lower blood pressure, lose weight, and restore metabolic abnormalities in OBH rats, which could be associated with the effects on protecting early renal damage. Finally, in the mechanism, HQQR increases SIRT1 mRNA and protein expression consistent with reduction of NF-κB acetylation and suppressed the p65-mediated inflammatory signaling pathway. As a result, HQQR robustly inhibits OBH-induced renal inflammation by reducing IL-6 mRNA and protein levels in the renal tissue and the release of IL-6 in serum of OBH rats. This study aims to provide a multimethod (network pharmacology-animal experiment) and multilevel (component-target-pathway) strategy for the prevention and treatment of OBH-induced target organ damage by traditional Chinese medicine.

Time-resolved Fluorescence Immunoassay (TRFIA) for the Simultaneous Detection of MMP-9 and Lp-PLA2 in Serum

Currently, atherosclerosis accounts for the majority of cardiovascular morbidity and mortality worldwide, and predicting the stability of atherosclerotic plaque is the main method to prevent atherosclerotic death. This study aims to establish a dual-label time-resolved fluorescence immunoassay (TRFIA) of matrix metalloprotein-9 (MMP-9) and lipoprotein-associated phospholipaseA2 (Lp-PLA2) to predict atherosclerotic plaque stability. A dual-label TRFIA was introduced for the simultaneous quantification of MMP-9 and Lp-PLA2 using fluorescent lanthanide (Eu³⁺ and Sm³⁺) chelates. The performance (sensitivity, specificity, accuracy, precision and reference intervals in different subjects) of this TRFIA was evaluated and compared with commercial kit. The sensitivity of the TRFIA for MMP-9 was 0.85 ng/mL and for Lp-PLA2 was 0.68 ng/mL with high affinity and specificity. The average recoveries were 94.58% to 109.82%, and 104.32% to 109.26%, respectively. All intra- and inter-assay CVs ranged from 3.10% to 5.46%. For the normal subjects, the cutoff value was 160.70 ng/mL for MMP-9 and 183.73 ng/mL for LP-PLA2; for the subjects with stable plaque, the cutoff value was 181.98~309.22 ng/mL for MMP-9 and 194.73~337.89 ng/mL for LP-PLA2; for the subjects with unstable plaque, the cutoff value was 330.43 ng/mL for MMP-9 and 343.23 ng/mL for LP-PLA2. This TRFIA detection results agreed well with the results of commercial kit (R²=0.9567 and R²=0.9771, respectively) in clinical serum samples. The TRFIA developed has a wide detection range and good sensitivity for the high-throughput simultaneous detection of MMP-9 and Lp-PLA2 in serum, which provides a new method for predicting the stability of atherosclerotic plaque.

Review: Detection and quantification of proteins in human urine

Extensive medical research showed that patients, with high protein concentration in urine, have various kinds of kidney diseases, referred to as proteinuria. Urinary protein biomarkers are useful for diagnosis of many health conditions – kidney and cardio vascular diseases, cancers, diabetes, infections. This review focuses on the instrumental quantification (electrophoresis, chromatography, immunoassays, mass spectrometry, fluorescence spectroscopy, the infrared spectroscopy, and Raman spectroscopy) of proteins (the most of all albumin) in human urine matrix. Different techniques provide unique information on what constituents of the urine are. Due to complex nature of urine, a separation step by electrophoresis or chromatography are often used for proteomics study of urine. Mass spectrometry is a powerful tool for the discovery and the analysis of biomarkers in urine, however, costs of the analysis are high, especially for quantitative analysis. Immunoassays, which often come with fluorescence detection, are major qualitative and quantitative tools in clinical analysis. While Infrared and Raman spectroscopies do not give extensive information about urine, they could become important tools for the routine clinical diagnostics of kidney problems, due to rapidness and low-cost. Thus, it is important to review all the applicable techniques and methods related to urine analysis. In this review, a brief overview of each technique's principle is introduced. Where applicable, research papers about protein determination in urine are summarized with the main figures of merits, such as the limit of detection, the detectable range, recovery and accuracy, when available.

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Urinary protein biomarkers are useful for diagnosis of many conditions: kidney and cardio vascular diseases, cancers.

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Liquid chromatography – mass spectroscopy is a powerful tool for urine proteomics, but used mostly in science.

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Immunoassays are widely used in both clinical and bio-analytical laboratories.

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IR and Raman spectroscopies are promising tools for diagnostics of urine due to low-cost and rapidness.

Simultaneous detection of fungal (1,3)-β-d-glucan and procalcitonin using a dual-label time-resolved fluorescence immunoassay

Neonatal infectious diseases are a serious threat to the health of newborns. The aim was to establish a new detection method for the simultaneous measurement of (1,3)-β-d-glucan and procalcitonin in serum for the early screening and efficacy testing of neonatal infectious diseases. We established a sandwich dual-label time-resolved fluorescence immunoassay (TRFIA): anti-(1,3)-β-d-glucan/procalcitonin antibodies immobilized on 96-well plates captured (1,3)-β-d-glucan/procalcitonin antigens and then banded together with the detection antibodies labeled with europium(III) (Eu³⁺ )/samarium(III) (Sm³⁺ ) chelates. Finally, time-resolved fluorometry was used to measure the fluorescence intensity. The linear correlation coefficient (R² ) of the (1,3)-β-d-glucan standard curve was 0.9913, and the R² of the procalcitonin standard curve was 0.9911. The detection sensitivity for (1,3)-β-d-glucan was 0.4 pg/mL (dynamic range: 0.6-90 pg/mL), and the average recovery was 101.55%. The detection sensitivity for procalcitonin was 0.02 ng/mL (dynamic range: 0.05-95 ng/mL), and the average recovery was 104.61%. There was a high R² between the present TRFIA method and a commercially available assay (R²  = 0.9829 for (1,3)-β-d-glucan and R²  = 0.9704 for procalcitonin). Additionally, the cutoff values for (1,3)-β-d-glucan and procalcitonin were 23.95 pg/mL and 0.055 ng/mL, respectively. The present TRFIA method has high sensitivity, accuracy, and specificity and is an effective method for early screening and efficient testing of neonatal invasive fungal infection.