Surface plasmon resonance imaging biosensor for cathepsin G based on a potent inhibitor: development and applications

Hepatitis C: The Story of a Long Journey through First, Second, and Third Generation NS3/4A Peptidomimetic Inhibitors. What Did We Learn?

Hepatitis C viral (HCV) infection is the leading cause of liver failure and still represents a global health burden. Over the past decade, great advancements made HCV curable, and sustained viral remission significantly improved to more than 98%. Historical treatment with pegylated interferon alpha and ribavirin has been displaced by combinations of direct-acting antivirals. These regimens include drugs targeting different stages of the HCV life cycle. However, the emergence of viral resistance remains a big concern. The design of peptidomimetic inhibitors (PIs) able to fit and fill the conserved substrate envelope region within the active site helped avoid contact with the vulnerable sites of the most common resistance-associated substitutions Arg155, Ala156, and Asp168. Herein, we give an overview of HCV NS3 PIs discovered during the past decade, and we deeply discuss the rationale behind the structural optimization efforts essential to achieve pangenotypic activity.

Surface Plasmon Resonance (SPR) Sensor for Cancer Biomarker Detection

A biomarker is a physiological observable marker that acts as a stand-in and, in the best-case scenario, forecasts a clinically significant outcome. Diagnostic biomarkers are more convenient and cost-effective than directly measuring the ultimate clinical outcome. Cancer is among the most prominent global health problems and a major cause of morbidity and death globally. Therefore, cancer biomarker assays that are trustworthy, consistent, precise, and verified are desperately needed. Biomarker-based tumor detection holds a lot of promise for improving disease knowledge at the molecular scale and early detection and surveillance. In contrast to conventional approaches, surface plasmon resonance (SPR) allows for the quick and less invasive screening of a variety of circulating indicators, such as circulating tumor DNA (ctDNA), microRNA (miRNA), circulating tumor cells (CTCs), lipids, and proteins. With several advantages, the SPR technique is a particularly beneficial choice for the point-of-care identification of biomarkers. As a result, it enables the timely detection of tumor markers, which could be used to track cancer development and suppress the relapse of malignant tumors. This review emphasizes advancements in SPR biosensing technologies for cancer detection.

An Array SPRi Biosensor for the Determination on PARP-1 in Blood Plasma

A biosensor was developed for the quantification of poly(ADP-ribose) polymerase-1 (PARP-1) in body fluids. An antibody specific for PARP-1 was placed on a chip with cysteamine (linker) and a gold layer. This biosensor has a linear response range (10-1000 pg∙mL^-1) under appropriate pH conditions and with an antibody ligand concentration of 5 ng∙mL^-1. Plasma samples were diluted with PBS buffer in appropriate quantities so that they fell within the linear range of the calibration curve. The biosensor exhibited suitable precision and accuracy, and good recovery (at levels from 95% to 105%). The method was validated by means of PARP-1 determinations in plasma samples from patients with endometriosis and a control group, using surface plasmon resonance imaging (SPRi) biosensors and an enzyme-linked immunosorbent assay (ELISA) test. The Spearman correlation coefficient was close to 1. PARP-1 may be a marker providing information about pathological changes in the body during endometriosis.

Methods of PARP-1 Determination and its Importance in Living Organisms

Abstract:

PARP-1 is one of the 18 PARP enzymes that are involved in important processes at the cellular level. The most important tasks of PARP-1 are to detect and repair DNA damage and to prevent processes of apoptosis. By finding and using new strategies for marking and detecting the activity of this protein, it is possible to identify more and more tasks in which it participates. In pathological states, PARP-1 activity increases significantly. Since the 1980s, scientists have been searching for and discussing substances that may inhibit PARP-1 activity and disrupt DNA damage response pathways. In this way, unwanted cells could be destroyed. The paper presents a short description of the methods used in the determination of PARP-1 by various research groups. A critical approach to each of them was also made by pointing to the advantages and disadvantages of the described analytical methods. The literature review contains information on methods useful for PARP-1 determination, such as SPR, QCM, CL and FL, DPV, SDS-PAGE with MS, MALDI MS, Western Blot, ELISA and ATR-FTIR spectroscopy. It also includes analysis of the results of research on inhibitors that may be effective in the diagnosis and treatment of cancer and other diseases.

Two SPRi biosensors for the determination of cathepsin S in blood plasma

Cathepsin S is an emerging marker for ovarian cancer. Two 'analytically specific' SPRi biosensors for the determination of Cath S have been developed. The reception part of one of the biosensors consists of the rat monoclonal antibody specific for cathepsin S attached to the gold surface via covalent bonds with cysteamine linker, while the second biosensor consists of the inhibitor LY3000328 attached via hydrophobic interaction with the 1-octadecanothiol linker. Under optimized conditions, in terms of pH and receptor concentration, both biosensors have linear response ranges between LOQ (0.14 ng mL^-1) and 2.5 ng mL^-1, which is suitable for the determination of Cath S in blood plasma samples of ovarian cancer patients and healthy individuals, after corresponding dilution with 0.15 M PBS buffer. Precision and recoveries are quite acceptable: below 7% and 98-101% respectively for the biosensor with antibody, and below 12% and 101-103% for the biosensor with inhibitor. The biosensors were validated by the determination of Cath S in series of plasma from ovarian cancer patients and healthy volunteers using both biosensors and ELISA, giving Pearson coefficients close to 1. Plasma Cath S concentration can be used as an ovarian cancer marker, in view of the highly elevated concentrations detected.

Plasma concentration of MMP-1 and MMP-2 in boys with cryptorchidism and its lack of correlation with INSL3 and inhibin B

The matrix metalloproteinases are enzymes capable of remodeling of extracellular matrix, and modulate the behavior of cells. Maturation of gubernaculum and spermatogenesis demand proper equilibrium of metalloproteinases and their inhibitors. The aim of this survey was to investigate the levels of matrix metalloproteinase type 1 (MMP-1) and matrix metalloproteinase type 2 (MMP-2) in the plasma of children with unilateral cryptorchidism along with levels of Insulin-like Peptide 3 (INSL3) and inhibin B. INSL3 have a role in gubernaculum development. Inhibin B is produced by Sertoli cells, and its levels reflect the status of the testis germinative epithelium. Fifty boys with an undescended testicle, aged 1-4 years (median = 2.4 years) were enrolled into the study. Fifty boys with inguinal hernia aged 1-4 years, served as controls (median age = 2.1 years). Investigators assessed the MMP-1 and MMP-2 concentrations using Surface Plasmon Resonance Imaging. The levels of INSL-3 and inhibin B were assessed using commercial enzyme-linked immunosorbent assay ELISA. The median concentration of MMP-1 and MMP-2 in the blood plasma of patients with unilateral cryptorchidism, was nearly 2-folds higher than in controls. The great area under the ROC curve with the cut off value of 0.865 for MMP-1, and 0.819 for MMP-2, indicates the high clinical sensitivity and specificity of the test of plasma levels of MMP-1 and MMP-2 for boys with cryptorchidism. The increased plasma levels of MMP-1 and MMP-2, probably reflect the level of apoptosis of the germ cells in undescended testicles, in response to the heat stress during the period of prepubertal testis development. In the group of cryptorchid boys, we found slightly lower concentrations of INSL3, without statistical significance and without correlation with MMP-1 and MMP-2 levels. There were no significant differences in the levels of inhibin B in the group of boys with cryptorchidism and boys with inguinal hernia and it also did not correlate with MMP-1 and MMP-2 concentrations.

Advances in Surface Plasmon Resonance Imaging and Microscopy and Their Biological Applications

Surface plasmon resonance microscopy and imaging are optical methods that enable observation and quantification of interactions of nano- and microscale objects near a metal surface in a temporally and spatially resolved manner. This review describes the principles of surface plasmon resonance microscopy and imaging and discusses recent advances in these methods, in particular, in optical platforms and functional coatings. In addition, the biological applications of these methods are reviewed. These include the detection of a broad variety of analytes (nucleic acids, proteins, bacteria), the investigation of biological systems (bacteria and cells), and biomolecular interactions (drug-receptor, protein-protein, protein-DNA, protein-cell).

Saliva, a Magic Biofluid Available for Multilevel Assessment and a Mirror of General Health-A Systematic Review

Background: Saliva has been recently proposed as an alternative to classic biofluid analyses due to both availability and reliability regarding the evaluation of various biomarkers. Biosensors have been designed for the assessment of a wide spectrum of compounds, aiding in the screening, diagnosis, and monitoring of pathologies and treatment efficiency. This literature review aims to present the development in the biosensors research and their utility using salivary assessment. Methods: a comprehensive literature search has been conducted in the PubMed database, using the keywords “saliva” and “sensor”. A two-step paper selection algorithm was devised and applied. Results: The 49 papers selected for the present review focused on assessing the salivary biomarkers used in general diseases, oral pathologies, and pharmacology. The biosensors proved to be reliable tools for measuring the salivary levels of biochemical metabolic compounds such as glucose, proteinases and proteins, heavy metals and various chemical compounds, microorganisms, oncology markers, drugs, and neurotransmitters. Conclusions: Saliva is a biofluid with a significant clinical applicability for the evaluation and monitoring of a patient’s general health. Biosensors designed for assessing a wide range of salivary biomarkers are emerging as promising diagnostic or screening tools for improving the patients’ quality of life.

Ultrasensitive Detection of Bacterial Protein Toxins on Patterned Microarray via Surface Plasmon Resonance Imaging with Signal Amplification by Conjugate Nanoparticle Clusters

Sensitive detection and monitoring of biological interactions in a high throughput, multiplexed array format has numerous advantages. We report here a method to enhance detection sensitivity in surface plasmon resonance (SPR) spectroscopy and SPR imaging via the effect of accumulation of conjugated nanoparticles of varying sizes. Bacterial cholera toxin (CT) was chosen for the demonstration of enhanced immunoassay by SPR. After immobilization of CT on a gold surface, specific recognition is achieved by biotinylated anti-CT. The signal is amplified by the attachment of biotinylated 20 nm AuNP via streptavidin bridge, followed by attachment of 5 nm streptavidin-functionalized Fe₃O₄NP to the AuNP-biotin surface. The continuous surface binding of two differently sized conjugated nanoparticles effectively increases their packing density on surface and significantly improves SPR detection sensitivity, allowing quantitative measurement of CT at very low concentration. The dense packing of conjugated nanoparticles on the surface was confirmed by atomic force microscopy characterization. SPR imaging of the immunoassay for high-throughput analysis utilized an Au-well microarray that attenuated the background resonance interference on the resulting images. A calibration curve of conjugated nanoparticle binding signal amplification for CT detection based on surface coverage has been obtained that shows a correlation in a range from 6.31 × 10^-16 to 2.51 × 10^-13 mol/cm² with the limit of detection of 5.01 × 10^-16 mol/cm². The absolute quantity of detection limit using SPR imaging was 0.25 fmol. The versatile nanoparticles and biotin-streptavidin interaction used here should allow adaptation of this enhancement method to many other systems that include DNA, RNA, peptides, and carbohydrates, opening new avenues for ultrasensitive analysis of biomolecules.

Cathepsin G Is Expressed by Acute Lymphoblastic Leukemia and Is a Potential Immunotherapeutic Target

Cathepsin G (CG) is a myeloid azurophil granule protease that is highly expressed by acute myeloid leukemia (AML) blasts and leukemia stem cells. We previously identified CG1 (FLLPTGAEA), a human leukocyte antigen-A2-restricted nonameric peptide derived from CG, as an immunogenic target in AML. In this report, we aimed to assess the level of CG expression in acute lymphoid leukemia (ALL) and its potential as an immunotherapeutic target in ALL. Using RT-PCR and western blots, we identified CG mRNA and protein, respectively, in B-ALL patient samples and cell lines. We also examined CG expression in a large cohort of 130 patients with ALL via reverse-phase protein array (RPPA). Our data show that CG is widely expressed by ALL and is a poor prognosticator. In addition to endogenous expression, we also provide evidence that CG can be taken up by ALL cells. Finally, we demonstrate that patient ALL can be lysed by CG1-specific cytotoxic T lymphocytes in vitro. Together, these data show high expression of CG by ALL and implicate CG as a target for immunotherapy in ALL.

SPR imaging biosensor for the quantitation of fibronectin concentration in blood samples

The purpose of this study was presentation of a new biosensor capable of determination of fibronectin. This biosensor was based on the specific interaction of anti-fibronectin antibody produced in rabbit with fibronectin. The surface plasmon resonance imaging (SPRI) technique was used as a detecting method. Optimization and characterization properties of the biosensor were studied. The determination of fibronectin concentration in natural samples was done. The results were compared with a reference method (Enzyme-Linked Immunosorbent Assay-ELISA). The analytically useful dynamic response range of biosensor is between 5 and 400ngmL^-1. The detection limit is 1.5ngmL^-1 and limit quantification is 5ngmL^-1. The proposed SPRI biosensor showed good selectivity for potential interferences. It was applied to determine fibronectin concentrations in plasma of healthy donors and of patients after thermal injury. Good correlations between results obtained using the SPRI biosensor and ELISA test (correlation coefficients for healthy donors 0.996, for patients 0.984) were obtained. The average fibronectin concentration of healthy donors was 140.5±24.6μgmL ^-1 and the average fibronectin concentration of patients was 601.5±72.1μgmL ^-1, which was in agreement with results obtained by other investigators. The obtained results indicate that the developed biosensor may be a candidate for monitoring fibronectin concentration in blood samples.

Overexpression of ubiquitin carboxyl-terminal hydrolase L1 (UCHL1) in serum of children after thermal injury

PURPOSE

The study aims to determinate concentrations of ubiquitin C-terminal hydrolase 1 (UCHL1), which hydrolyzes amino acids from ubiquitin and cleave di-ubiquitins, in serum of children after thermal injury.

PATIENTS/METHODS

42 children scalded by hot water, managed at the Department of Pediatric Surgery, with burns in 4-20% TBSA were included into the study (age 9 months up to 14 years, mean age 2.5±1 years). Blood plasma UCHL1 concentration was assessed in 2-6h, 12-16h, 3d, 5d, and 7d after injury using surface plasmon resonance imaging biosensor. 18 healthy subjects admitted for planned surgeries served as controls.

RESULTS

The UCHL1 concentration in the blood plasma of patients with thermal injuries reached its peak 12-16h after thermal injury and slowly decreased over time, and still did not reach the normal range on the 7th day after thermal injury. Mean concentrations of UCHL1 after thermal injury were above the range measured in controls (0.12ng/ml): 2-6h after injury - 5.59ng/dl, 12-16h after injury - 9.16ng/dl, 3 days after injury - 6.94ng/dl, 5 days after 5.41ng/dl, 7 days after injury - 4.09ng/dl.

CONCLUSIONS

We observed sudden increase in the concentration of UCHL1 2-16h after thermal injury with the slow decrease in the UCHL1 concentration over the time. UCHL1 concentration was proportional to the severity of the burn. Further studies are needed to determine the mechanisms by which UCHL1 contributes to metabolic response following thermal injury.

Surface Plasmon Resonance Clinical Biosensors for Medical Diagnostics

The design and application of sensors for monitoring biomolecules in clinical samples is a common goal of the sensing research community. Surface plasmon resonance (SPR) and other plasmonic techniques such as localized surface plasmon resonance (LSPR) and imaging SPR are reaching a maturity level sufficient for their application in monitoring biomolecules in clinical samples. In recent years, the first examples for monitoring antibodies, proteins, enzymes, drugs, small molecules, peptides, and nucleic acids in biofluids collected from patients afflicted with a series of medical conditions (Alzheimer's, hepatitis, diabetes, leukemia, and cancers such as prostate and breast cancers, among others) demonstrate the progress of SPR sensing in clinical chemistry. This Perspective reviews the current status of the field, showcasing a series of early successes in the application of SPR for clinical analysis and detailing a series of considerations regarding sensing schemes, exposing issues with analysis in biofluids, and comparing SPR with ELISA, while providing an outlook of the challenges currently associated with plasmonic materials, instrumentation, microfluidics, bioreceptor selection, selection of a clinical market, and validation of a clinical assay for applying SPR sensors to clinical samples. Research opportunities are proposed to further advance the field and transition SPR biosensors from research proof-of-concept stage to actual clinical applications.

Methods for 20S Immunoproteasome and 20S Constitutive Proteasome Determination Based on SPRI Biosensors

The 20S proteasome, released into the circulation, is a novel cancer biomarker. It exists in two forms: the constitutive proteasome (20Sc) and the immunoproteasome (20Si), which both have separate diagnostic significance. The aim of this work was to develop new methods for 20Si and 20Sc determination. Five alternative specific biosensors usable with the surface plasmon resonance imaging (SPRI) technique for 20Si determination have been developed. Specific 20Si entrapment on the biosensor surface from an analyzed solution was achieved by means of an immobilized specific 20Si receptor. Four of the biosensors contain newly synthesized specific 20Si receptors, while the fifth contains the inhibitor ONX 0914. A method for 20Sc determination using an SPRI biosensor containing PSI inhibitor has been developed. By the introduction of an inhibitor blocking 20Si, 20Sc is selectively determined. All of the methods developed for 20Si and 20Sc determination exhibit good selectivity and satisfactory precision, recoveries and dynamic response ranges. 20Si and 20Sc were determined in blood plasma samples from healthy donors and patients with acute leukemia. In the case of these patients 20Si was the major component, and its level was more than one order of magnitude higher than in the healthy donors.

SPR imaging biosensor for determination of laminin-5 as a potential cancer marker in biological material

A new method for the selective determination of laminin-5 concentration using a biosensor and surface plasmon resonance imaging (SPRI) technique is presented. A biosensor based on the specific interaction of laminin-5 with rabbit polyclonal antibody was constructed. The analytically useful dynamic response range of the biosensor is between 0.014 and 0.1 ng mL(-1). The detection limit is 4 pg mL(-1). The potential influence of interferences on the SPRI signal was investigated, and the high selectivity of the biosensor was confirmed. In order to demonstrate the potential application of the biosensor, laminin-5 concentration in blood plasma was determined. The results were compared with the laminin-5 concentration obtained by the commercial enzyme-linked immunosorbent assay (ELISA) kit. A comparison of results from healthy donors obtained by SPRI measurement and ELISA indicates that they are close and shows good agreement with the data reported in the literature. The plasma samples of bladder cancer patients gave higher concentration measured with specific biosensor than by ELISA assay. The study shows the clear difference in concentration of laminin-5 in healthy humans and patients with bladder cancer. Extensive clinical studies using the newly developed method can result in an increase in the use of laminin-5 as a potential cancer marker.

Synthesis of novel phosphonic-type activity-based probes for neutrophil serine proteases and their application in spleen lysates of different organisms

Neutrophils are a type of granulocyte important in the "first line of defense" of the innate immune system. Upon activation, they facilitate the destruction of invading microorganisms by the production of superoxide radicals, as well as the release of the enzymatic contents of their lysozymes. These enzymes include specific serine proteases: cathepsin G, neutrophil elastase, proteinase 3, as well as the recently discovered neutrophil serine protease 4 (NSP4). Under normal conditions, the proteolytic activity of neutrophil proteases is tightly regulated by endogenous serpins; however, this mechanism can be subverted during tissue stress, thereby resulting in the uncontrolled activity of serine proteases, which induce chronic inflammation and subsequent pathology. Herein, we describe the development of low-molecular-weight activity-based probes that specifically target the active sites of neutrophil proteases.

A novel HLA-A*0201 restricted peptide derived from cathepsin G is an effective immunotherapeutic target in acute myeloid leukemia

PURPOSE

Immunotherapy targeting aberrantly expressed leukemia-associated antigens has shown promise in the management of acute myeloid leukemia (AML). However, because of the heterogeneity and clonal evolution that is a feature of myeloid leukemia, targeting single peptide epitopes has had limited success, highlighting the need for novel antigen discovery. In this study, we characterize the role of the myeloid azurophil granule protease cathepsin G (CG) as a novel target for AML immunotherapy.

EXPERIMENTAL DESIGN

We used Immune Epitope Database and in vitro binding assays to identify immunogenic epitopes derived from CG. Flow cytometry, immunoblotting, and confocal microscopy were used to characterize the expression and processing of CG in AML patient samples, leukemia stem cells, and normal neutrophils. Cytotoxicity assays determined the susceptibility of AML to CG-specific cytotoxic T lymphocytes (CTL). Dextramer staining and cytokine flow cytometry were conducted to characterize the immune response to CG in patients.

RESULTS

CG was highly expressed and ubiquitinated in AML blasts, and was localized outside granules in compartments that facilitate antigen presentation. We identified five HLA-A*0201 binding nonameric peptides (CG1-CG5) derived from CG, and showed immunogenicity of the highest HLA-A*0201 binding peptide, CG1. We showed killing of primary AML by CG1-CTL, but not normal bone marrow. Blocking HLA-A*0201 abrogated CG1-CTL-mediated cytotoxicity, further confirming HLA-A*0201-dependent killing. Finally, we showed functional CG1-CTLs in peripheral blood from AML patients following allogeneic stem cell transplantation.

CONCLUSION

CG is aberrantly expressed and processed in AML and is a novel immunotherapeutic target that warrants further development.