Surface Plasmon Resonance Imaging Research Articles

Application of surface Plasmon resonance imaging in the high-throughput detection of influenza virus.

To evaluate the application effect of SPRi monoclonal antibody (mAb) chip in the detection of influenza virus antigen in complex mixtures. A total of 115 strains of mAbs against different subtypes (H1N1, H5N1, A1, A3, B, H7N9, H9N2, and H3N2) of influenza virus were prepared. The chip of mAbs against influenza virus was prepared by surface plasmonic resonance imaging (SPRi) technology, which was used for the detection of influenza virus supernatant, and compared with the traditional antigen capture ELISA method. Comparative studies have shown that traditional antigen capture ELISA methods have a higher sensitivity (86.8% (46/53) vs. 46.5% (46/99); z = 4.84, P < .001), while the SPRi chip methods present a significantly higher specificity (56.3% (9/16) vs. 14.5% (9/62); z = 3.54, P < .001). The SPRi chip detection method for influenza virus antibodies can well reflect the specific binding characteristics of influenza virus antigens and antibodies. The SPRi mAb chip can be used for the detection of specific pathogenic microorganisms or viral proteins in complex mixtures such as influenza virus supernatant. It has significant advantages of label free, real-time, high-throughput, and good specificity, and can play an important role in disease diagnosis and infectious disease prevention and control.

In Situ and Label-Free Quantification of Membrane Protein–Ligand Interactions Using Optical Imaging Techniques: A Review

Membrane proteins are crucial for various cellular processes and are key targets in pharmacological research. Their interactions with ligands are essential for elucidating cellular mechanisms and advancing drug development. To study these interactions without altering their functional properties in native environments, several advanced optical imaging methods have been developed for in situ and label-free quantification. This review focuses on recent optical imaging techniques such as surface plasmon resonance imaging (SPRi), surface plasmon resonance microscopy (SPRM), edge tracking approaches, and surface light scattering microscopy (SLSM). We explore the operational principles, recent advancements, and the scope of application of these methods. Additionally, we address the current challenges and explore the future potential of these innovative optical imaging strategies in deepening our understanding of biomolecular interactions and facilitating the discovery of new therapeutic agents.

Is Osteopontin a Reliable Biomarker for Endometriosis?

This study aimed to evaluate the concentration of osteopontin in peritoneal fluid and plasma as potential biomarkers for diagnosing endometriosis. Osteopontin levels were measured using surface plasmon resonance imaging (SPRI) biosensors in patients suspected of having endometriosis. Plasma samples were collected from 120 patients, and peritoneal fluid was collected from 86 patients. Based on the detection of endometriosis lesions during laparoscopy, participants were divided into a study group (patients with endometriosis) and a control group (patients without endometriosis). The results showed no significant differences in plasma osteopontin levels between women with endometriosis and the control group (19.86 ± 6.72 ng/mL vs. 18.39 ± 4.46 ng/mL, p = 0.15). Similarly, peritoneal fluid osteopontin concentrations did not differ significantly between patients with and without endometriosis (19.04 ± 5.37 ng/mL vs. 17.87 ± 5.13 ng/mL, p = 0.29). Furthermore, osteopontin levels in both plasma and peritoneal fluid were not significantly associated with the stage of endometriosis, the presence of endometrioma, or the menstrual cycle phase. The findings of this study do not support osteopontin concentration as a reliable biomarker for endometriosis. However, further research is necessary to explore osteopontin’s potential role in the disease.

Developing surface plasmon resonance imaging for discrete particle detection based on a silver layer coated with polyacrylic acid/iodine polyelectrolyte brushes

The detection and analysis of low concentrations of chemical and biological particles present an enduring challenge in scientific exploration. Among the various techniques employed for this purpose, surface plasmon resonance (SPR) stands as a powerful label-free method with wide-range applications in advanced detection and sensing. Traditional SPR, while highly effective, encounters inherent limitations when it comes to scrutinizing individual particles. To overcome this limitation, wide-field surface plasmon resonance microscopy emerges as a promising approach, offering real-time detection capabilities for suspended particles in solution. In this study, we present an innovative wide-field surface plasmon resonance microscope, strategically combining a silver layer coated with polyelectrolyte brushes—polyacrylic acid/iodine to enhance the detection sensitivity and mitigate silver’s susceptibility to oxidation. It was demonstrated that coating the silver layer with polyacrylic acid/iodine enhances the sensitivity of discrete particle imaging with high spatial resolution of the recorded image. Since wide-field surface plasmon resonance microscopy can detect discrete particles, we present a mathematical model to describe the SPR sensing mechanism based on discrete particles for precisely characterizing and interpreting our experimental observations. The work demonstrates a capability for comprehensive analysis of low concentrations of chemical and biological particles at the single particle level.

Detection of morphine and data processing using surface plasmon resonance imaging sensor

Abstract Based on the surface plasmon resonance imaging (SPRi) instrument, we established a new method of analyzing morphine in urine by processing a calibration curve. According to an inhibition immunoassay, gradient concentration of morphine and morphine-BSA fixed on the chip competitively combine with morphine antibody on the chip. Given the three mathematical models, the data of SPRi signals generated from SPRi with morphine was processed to obtain the calibration curve. Ultrafiltration was used to pretreat blank urine samples with adding morphine, and then investigated the advantages and disadvantages of each model. With a limit detection of 6.57 ng·mL−1, the method and mathematical models can provide robust support for SPRi sensors used in further environmental detection, such as the epidemiological study of sewage.

Rapid wavelength interval selection technology for multi-channel intensity-interrogation surface plasmon resonance imaging sensing

Intensity-interrogation surface plasmon resonance (I-SPR) provides the fastest imaging speed among various SPR techniques, including wavelength, phase, and angle-based detection. It also integrates easily with other devices and has substantial practical application potential. However, I-SPR's reliance on direct detection of reflected light intensity renders it sensitive to light source fluctuations and detector dark noise, and its dynamic range is relatively limited. To address these challenges, we have developed a multi-channel I-SPR sensing platform featuring rapid wavelength interval selection technology. This system optimizes the sensing wavelength according to the refractive indices of different samples, mitigating issues related to inconsistent SPR signals from various biomolecules. Our improved I-SPR technology enables high-throughput biomolecular detection with a refractive index range size of 2.035 × 10−2 for dynamic monitoring, reaching a leading role among the existing I-SPR technologies. This represents the widest linear dynamic range for I-SPR to date. Experimental results on protein binding kinetic constants KD are consistent with those obtained from commercially available instruments. We believe that this study is expected to accelerate the development of SPR technology toward broader biological applications.

Surface Plasmon Resonance Imaging (SPRi)-based Immunobiosensor for the Detection and Comprehensive Analysis of Acetylcholine Receptor (AChR) Antibodies in Myathenia Gravis

Surface Plasmon Resonance Imaging (SPRi)-based Immunobiosensor for the Detection and Comprehensive Analysis of Acetylcholine Receptor (AChR) Antibodies in Myathenia Gravis

Raman spectroscopy of large extracellular vesicles derived from human microvascular endothelial cells to detect benzo[a]pyrene exposure.

Extracellular vesicles (EVs) have shown great potential as biomarkers since they reflect the physio-pathological status of the producing cell. In the context of cytotoxicity, it has been found that exposing cells to toxicants leads to changes in protein expression and the cargo of the EVs they produce. Here, we studied large extracellular vesicles (lEVs) derived from human microvascular endothelial cells (HMEC-1) to detect the modifications induced by cell exposure to benzo[a]pyrene (B[a]P). We used a custom CaF2-based biochip which allowed hyphenated techniques of investigation: surface plasmon resonance imaging (SPRi) to monitor the adsorption of objects, atomic force microscopy (AFM) to characterise EVs' size and morphology, and Raman spectroscopy to detect molecular modifications. Results obtained on EVs by Raman microscopy and tip-enhanced Raman spectroscopy (TERS) showed significant differences induced by B[a]P in the high wavenumber region of Raman spectra (2800 to 3000cm-1), corresponding mainly to lipid modifications. Two types of spectra were detected in the control sample. A support vector machine (SVM) model was trained on the pre-processed spectral data to differentiate between EVs from cells exposed or not to B[a]P at the spectrum level; this model could achieve a sensitivity of 88% and a specificity of 99.5%. Thus, this experimental setup facilitated the distinction between EVs originating from two cell culture conditions and enabled the discrimination of EV subsets within one cell culture condition.

Key role of PPAR-γ-mediated suppression of the NFκB signaling pathway in rutin's antidepressant effect

BackgroundDepression is a chronic and recurrent disorder with an unknown etiology. Efficacious antidepressant treatments with minimal side effects are urgently needed. Neuroinflammation may contribute to depression, as anti-inflammatory drugs have been shown to alleviate depressive symptoms in clinical practice. Rutin, a naturally occurring flavonoid derived from plants, is abundant in many antidepressant herbs, including Hemerocallis citrina Baroni. Historical Chinese medical texts, including the renowned Compendium of Materia Medica, document H. citrina Baroni as possessing antidepressant properties. Rutin, one of its primary active constituents, is recognized for its anti-inflammatory effects. Despite this, little is known about its specific target and mechanism. MethodsIn the present study, molecular docking, and surface plasmon resonance imaging (SPRi) analysis were used to identify the special targets of rutin. Meanwhile, the potential antidepressant effects were evaluated in the chronic social defeat stress (CSDS) paradigm, an animal model of depression. Then, Western blotting, quantitative real-time polymerase chain reaction (qRT-PCR), Co-immunoprecipitation (Co-IP) as well as antagonists of PPAR-γ were utilized to investigate the mechanism underlying the antidepressant effect of rutin. ResultsBoth molecular docking and SPRi analysis showed high docking scores and interactions between rutin and PPAR-γ. In vivo, rutin promoted the nuclear translocation of PPAR-γ in the hippocampus of mice, inhibited NFκB-mediated inflammatory pathways, and subsequently reduced the expression of pro-inflammatory factors (e.g., iNOS, IL-6), aligning with an antidepressant effect. However, this therapeutic effect was attenuated by GW9662, a specific antagonist of PPAR-γ. ConclusionAs a result of activating PPAR-γ and inhibiting NFκB pathway activation, rutin reduces neuroinflammation and exhibits an antidepressant effect. These findings shed light on the antidepressant mechanism of rutin and could be valuable for the development of new antidepressants.

Clinical significance of S100B protein in pregnant woman with early- onset severe preeclampsia.

Preeclampsia is one of the most feared complications of pregnancy, which can progress rapidly to serious complications such as death of both mother and fetus. To present, the leading cause of preeclampsia is still debated. The purpose of this article was to explore the clinical significance of S100B protein, a kind of Ca2+ -sensor protein, in the early-onset severe preeclampsia. Nine pregnant women with early-onset severe preeclampsia (the study group) and 13 healthy pregnant women (the control group) were included in this study. The level of S100B in the amniotic fluid, maternal blood, and umbilical cord blood were detected by enzyme-linked immunosorbent assay (ELISA) and surface plasmon resonance imaging (SPRi) methods. Diagnostic values of S100B for early-onset severe preeclampsia were assessed by Receiver Operating Characteristic (ROC) curve analysis. The levels of S100B in maternal blood and amniotic fluid in the study group were higher than those in the control group (p < 0.05). ROC curve analysis showed that S100B detected by SPRi method (SPRi-S100B) showed a cut-off level of 181 ng/mL with sensitivity of 100%, a specificity of 84.6%, and a Youden index of 0.846 in the maternal blood, which had better clinical significance and diagnostic value (at than that detected by ELISA (ELISA-S100B). The levels of S100B detected by SPRi in maternal blood can indicate early-onset severe preeclampsia and perinatal brain injury.

Application of Surface Plasmon Resonance Imaging Biosensors for Determination of Fibronectin, Laminin-5, and Type IV Collagen in Plasma, Urine, and Tissue of Renal Cell Carcinoma.

Laminin, fibronectin, and collagen IV are pivotal extracellular matrix (ECM) components. The ECM environment governs the fundamental properties of tumors, including proliferation, vascularization, and invasion. Given the critical role of cell-matrix adhesion in malignant tumor progression, we hypothesize that the concentrations of these proteins may be altered in the plasma of patients with clear cell renal cell carcinoma (ccRCC). This study aimed to evaluate the serum, urine, and tissue levels of laminin-5, collagen IV, and fibronectin among a control group and ccRCC patients, with the latter divided into stages T1-T2 and T3-T4 according to the TNM classification. We included 60 patients with histopathologically confirmed ccRCC and 26 patients diagnosed with chronic cystitis or benign prostatic hyperplasia (BPH). Collagen IV, laminin-5, and fibronectin were detected using Surface Plasmon Resonance Imaging biosensors. Significant differences were observed between the control group and ccRCC patients, as well as between the T1-T2 and T3-T4 subgroups. Levels were generally higher in plasma and tissue for fibronectin and collagen IV in ccRCC patients and lower for laminin. The ROC (Receiver operating characteristic) analysis yielded satisfactory results for differentiating between ccRCC patients and controls (AUC 0.84-0.93), with statistical significance for both fibronectin and laminin in plasma and urine. Analysis between the T1-T2 and T3-T4 groups revealed interesting findings for all examined substances in plasma (AUC 0.8-0.95). The results suggest a positive correlation between fibronectin and collagen levels and ccRCC staging, while laminin shows a negative correlation, implying a potential protective role. The relationship between plasma and urine concentrations of these biomarkers may be instrumental for tumor detection and staging, thereby streamlining therapeutic decision-making.

Strategic approaches to enhance efficiency and commercial feasibility of copper-based surface plasmon resonance sensing

Despite enormous progress in the field of surface plasmon resonance (SPR) imaging sensor technology in the past three decades, noble metals like Au and Ag, despite their drawbacks, continue to be the metals of choice for plasmonic sensing layers. The conventional architecture of the SPR sensor based on gold/silver and glass prism hinders scaling, portability, and industrial manufacturing. In this contribution, we present a novel architecture of SPR sensor using copper on polycarbonate prism as a cost-effective, scalable, and mass-producible alternative. Various optimization techniques, such as interface layer, protective encapsulation, and 2D affinity layer are explored to address the challenges related to the practical application of copper in a plasmonic sensor. Our results show that optimized architectures of SPR sensor based on copper has a sensitivity of 235.01°/RIU. From a quantitative analysis of the interrelationships among various performance parameters, we have derived a comprehensive sensing parameter that integrates signal quality and sensitivity. The proposed architecture of the copper based SPR sensor can lead to inexpensive, compact, and handy probes that do not sacrifice accuracy or reliability.

Development of a Novel Peptide-Based PET Tracer [68Ga]Ga-DOTA-BP1 for BCMA Detection in Multiple Myeloma.

B-cell maturation antigen (BCMA) has emerged as a promising tumor marker for the diagnosis and treatment of multiple myeloma. The noninvasive and rapid detection of BCMA expression in vivo provides significant value in screening and evaluating multiple myeloma patients receiving BCMA-targeted therapy. We identified the BCMA-targeting peptide BP1 from a one-bead-one-compound (OBOC) peptide library using a high-throughput microarray strategy. The BCMA-targeting specificity and affinity of BP1 were assessed by surface plasmon resonance imaging (SPRi), flow cytometry, and confocal imaging. BCMA-positive (H929) and BCMA-negative (K562) subcutaneous tumor models were established and labeled with 68Ga for BP1, followed by PET imaging and biodistribution studies. PET imaging demonstrated that 68Ga-labeled BP1 has significant specific uptake in multiple myeloma, enabling rapid identification of BCMA expression and precise delineation of the disease. Thus, BP1 represents an ideal candidate for multiple myeloma imaging.

Oxidative Modifications of Proteins and Lipids of Dried Semen, Urine, and Saliva Stains as a Function of Age in Forensic Context

Knowledge of the time of deposition is pivotal in forensic investigations. Recent studies show that changes in intrinsic fluorescence over time can be used to estimate the age of body fluids. These changes have been attributed to oxidative modifications caused by protein–lipid interactions. This pilot study aims to explore the impact of these modifications on body fluid fluorescence, enhancing the protein–lipid model system for age estimation. Lipid and protein oxidation markers, including protein carbonyls, dityrosine, advanced glycation end-products (AGEs), malondialdehyde (MDA), and 4-hydroxynonenal (HNE), were studied in aging semen, urine, and saliva over 21 days. Surface plasmon resonance imaging (SPRi), enzyme-linked immunosorbent assay (ELISA), and fluorescence spectroscopy were applied. Successful detection of AGE, dityrosine, MDA, and HNE occurred in semen and saliva via SPRi, while only dityrosine was detected in urine. Protein carbonyls were measured in all body fluids, but only in saliva was a significant increase observed over time. Additionally, protein fluorescence loss and fluorescent oxidation product formation were assessed, showing significant decreases in semen and saliva, but not in urine. Although optimization is needed for accurate quantification, this study reveals detectable markers for protein and lipid oxidation in aging body fluids, warranting further investigation.

Detection of gentamicin in water and milk using chitosan-ZnS-Au nanocomposite based on surface plasmon resonance imaging sensor

The detection of antibiotics in milk, water, and agricultural products is a topic of interest for health care and environmental protection. Some antibiotics such as oxytetracycline and gentamicin are the prominent contaminants in water and milk. In this study, the chitosan-ZnS and chitosan-ZnS-Au nanocomposites were fabricated using a laser ablation technique. The nanocomposites were covered on the glass substrate as a layer sensor characterized by analytical methods. Consequently, the thickness of layers was in the range of 36.3 to 38.21 nm. The surface plasmon resonance image patterns demonstrated the interaction of the gentamicin and oxytetracycline with nanocomposites. As a result, the sensor is sensitive to detect gentamicin, and the limit of detection, the affinity constant, and response time were about 0.1 ppm, 102.04 a.u., and 268 s respectively.

Przewaquinone A inhibits Angiotensin II-induced endothelial diastolic dysfunction activation of AMPK

BackgroundEndothelial dysfunction (ED), characterized by markedly reduced nitric oxide (NO) bioavailability, vasoconstriction, and a shift toward a proinflammatory and prothrombotic state, is an important contributor to hypertension, atherosclerosis, and other cardiovascular diseases. Adenosine 5′-monophosphate (AMP)-activated protein kinase (AMPK) is widely involved in cardiovascular development. Przewaquinone A (PA), a lipophilic diterpene quinone extracted from Salvia przewalskii Maxim, inhibits vascular contraction. PurposeHerein, the goal was to explore the protective effect of PA on ED in vivo and in vitro, as well as the underlying mechanisms. MethodsA human umbilical vein endothelial cell (HUVEC) model of ED induced by angiotensin II (AngII) was used for in vitro observations. Levels of AMPK, endothelial nitric oxide synthase (eNOS), vascular cell adhesion molecule-1 (VCAM-1), nitric oxide (NO), and endothelin-1 (ET-1) were detected by western blotting and ELISA. A mouse model of hypertension was established by continuous infusion of AngII (1000 ng/kg/min) for 4 weeks using osmotic pumps. Following PA and/or valsartan administration, NO and ET-1 levels were measured. The levels of AMPK signaling-related proteins in the thoracic aorta were evaluated by immunohistochemistry. Systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP) were measured using the tail cuff method. Isolated aortic vascular tone measurements were used to evaluate the vasodilatory function in mice. Molecular docking, molecular dynamics, and surface plasmon resonance imaging (SPRi) were used to confirm AMPK and PA interactions. ResultsPA inhibited AngII-induced vasoconstriction and vascular adhesion as well as activated AMPK signaling in a dose-dependent manner. Moreover, PA markedly suppressed blood pressure, activated vasodilation in mice following AngII stimulation, and promoted the activation of AMPK signaling. Furthermore, molecular simulations and SPRi revealed that PA directly targeted AMPK. AMPK inhibition partly abolished the protective effects of PA against endothelial dysfunction. ConclusionPA activates AMPK and ameliorates endothelial dysfunction during hypertension.

Hydrogen peroxide and glucose detection using surface plasmon resonance imaging biosensor with corrodible silver thin film

A surface plasmon resonance imaging (SPRI)-based biosensor is demonstrated for the detection of both hydrogen peroxide (H2O2) and glucose. The H2O2 to be detected acts as an oxidant and etch the silver film. This process gradually effects on resonance condition and consequently the reflected light intensity at a fixed angle. The etching rate of the silver film shows a clear relation with the H2O2 concentration. Therefore, monitoring the reflected light intensity progressively changing over a few minutes, enables accurate detection of H2O2 concentrations ranging from 0 to 200 μM (within physiological range of 0.25–50 μM), with a remarkable limit of detection (LOD) as low as 40 nM. In this regard, the behavior of the surface plasmon resonance (SPR) dip in response to the reduction of the silver film thickness is predicted by Winspall simulation software. These simulation results are in good agreement with the experimental results. Moreover, the proposed method can be applied to determine glucose concentrations ranging from 0 to 10 mM, encompassing the physiological range of 3–8 mM. This is achieved by observing the generated H2O2 through the enzymatic oxidation reaction between glucose and glucose oxidase (Gox). The sensor demonstrates remarkable sensitivity and selectivity, with a detection limit as low as 175 μM for glucose concentration. Furthermore, accurate measurement of glucose concentration in an actual human serum sample is achievable with the proposed sensor, using the standard addition method. The suggested glucose sensor shows promising prospects for use in routine glucose testing, employing a label-free, real-time, and multiplex detection approach.© 2017 Elsevier Inc. All rights reserved.

TitrationAnalysis: a tool for high throughput binding kinetics data analysis for multiple label-free platforms

Label-free techniques including Surface Plasmon Resonance (SPR) and Biolayer Interferometry (BLI) are biophysical tools widely used to collect binding kinetics data of bimolecular interactions. To efficiently analyze SPR and BLI binding kinetics data, we have built a new high throughput analysis tool named the TitrationAnalysis. It can be used as a package in the Mathematica scripting environment and ultilize the non-linear curve-fitting module of Mathematica for its core function. This tool can fit the binding time course data and estimate association and dissociation rate constants (ka and kd respectively) for determining apparent dissociation constant (KD ) values. The high throughput fitting process is automatic, requires minimal knowledge on Mathematica scripting and can be applied to data from multiple label-free platforms. We demonstrate that the TitrationAnalysis is optimal to analyze antibody-antigen binding data acquired on Biacore T200 (SPR), Carterra LSA (SPR imaging) and ForteBio Octet Red384 (BLI) platforms. The ka , kd and KD values derived using TitrationAnalysis very closely matched the results from the commercial analysis software provided specifically for these instruments. Additionally, the TitrationAnalysis tool generates user-directed customizable results output that can be readily used in downstream Data Quality Control associated with Good Clinical Laboratory Practice operations. With the versatility in source of data input source and options of analysis result output, the TitrationAnalysis high throughput analysis tool offers investigators a powerful alternative in biomolecular interaction characterization.

Insights into Photopolymerization at the Nanoscale Using Surface Plasmon Resonance Imaging.

Near-field photopolymerization (NFPP) driven by surface plasmon resonance has attracted increasing attention in nanofabrication. This interest comes from the nanometer-scale control of polymer thickness, due to the confinement of the evanescent wave within a highly restricted volume at the surface. In this study, a novel approach using a multi-spectral surface plasmon resonance instrument is presented that gives access to real-time images of polymer growth during NFPP with nanometer sensitivity. Using the plasmonic evanescent wave for both polymerization and real-time sensing, the influence of irradiance, concentration of dye, and initiator are investigated on the threshold energy and kinetics of NFPP. How oxygen inhibition in the near field strongly affects photopolymerization is highlighted, more than in the far field.

20S constitutive proteasome, 20S immunoproteasome, and cathepsin S are high-sensitivity and independent markers of immunological activity in relapsing-remitting type of multiple sclerosis.

Research on the markers of autoimmune response in multiple sclerosis (MS) is still of great importance. The aim of our study was the evaluation of plasma 20S constitutive proteasome, 20S immunoproteasome, and cathepsin S concentrations as potential biomarkers of a relapsing-remitting type of MS (RRMS). Surface plasmon resonance imaging (SPRI) biosensors were used for the evaluation of protein concentrations. Plasma 20S constitutive proteasome, 20S immunoproteasome, and cathepsin S concentrations were significantly higher in RRMS patients compared to the control group. All three parameters were characterized by excellent usefulness in differentiating MS patients from healthy individuals (AUC equal to or close to 1.000). The plasma concentration of analyzed parameters was not correlated with severity of disability in the course of RRMS (EDSS value), the number of years from the first MS symptoms, the number of years from MS diagnosis, or the number of relapses within the 24-month observational period. Our study has shown that plasma concentrations of 20S constitutive proteasome, 20S immunoproteasome, and cathepsin S have promising potential in differentiating RRMS patients from healthy individuals. All of the analyzed parameters were found to be independent of the time of MS relapse and the severity of neurological symptoms. Hence, their potential as highly sensitive and independent circulating markers of RRMS suggests a stronger association with immunological activity (inflammatory processes) than with the severity of the disease.