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To assess the level of β2-microglubulin (β2M) in systemic lupus erythematosus (SLE) patients and its association with disease activity and other disease parameters. 40 SLE patients and 22 matched controls were studied. Serum β2M was assessed using enzyme-linked immunosorbent assay (ELISA). SLE Disease Activity Index (SLEDAI) and the damage index were assessed. The patients were 36 females and 4 males (F:M 9:1) with a mean age of 28.5 ± 7.9 years and disease duration of 6.7 ± 3.3 years. The SLEDAI was 9.3 ± 5.2 and the damage index 1.83 ± 1.84. The mean level of serum β2M was significantly higher in SLE patients (6.42 ± 2.46 mg/L) than control (2.47 ± 0.4 mg/L) (p < 0.01).The serum level of β2M was significantly higher in patients with nephritis (n = 22) (7.45 ± 2.47 mg/L) compared to those without (n = 18) (5.17 ± 1.82 mg/L)(p = 0.002), And it was similar in those with and without arthritis (7.24 ± 2.3 mg/L vs 5.88 ± 2.4 mg/L (p0.07).The β2M significantly correlated with disease activity (r = 0.86, p 0.001), serum creatinine (r = 0.52, p > 0.001), urea (r = 0.63, p < 0.001), 24 h urinary protein (r = 0.56, p < 0.001), hematuria (r = 0.4, p < 0.01) and pyuria (r = 0.41; p < 0.01), ESR (r = 0.48; p < 0.01) and inversely with hemoglobin level (r = −0.34; p = 0.03). No significant correlation was found with C-reactive protein or with disease damage. Serum (β2M) significantly predicted nephritis and disease activity (sensitivity 63.6 %, specificity 77.8 %; p < 0.001 and 95 %CI: 0.25–0.41; p < 0.001 respectively). Serum β2M is significantly associated with disease activity and lupus nephritis, suggesting that serum β2M may serve as a potential biomarker to monitor the disease activity and predicting lupus nephritis. However its association to disease severity needs further longitudinal studies. [ABSTRACT FROM AUTHOR]

Abstract We compared cerebrospinal fluid levels of lactate, β2-microglobulin and angiotensin-converting enzyme (ACE) between 438 untreated patients with multiple sclerosis and 276 patients with non-inflammatory neurological disorders. Age-adjusted β2-microglobulin and lactate were significantly higher and ACE was significantly lower in MS patients than in controls. β2-microglobulin and ACE positively correlated with high significance both in MS patients and controls. While disease duration negatively correlated and progression index, defined as EDSS score divided by disease duration in years, positively correlated with age-adjusted lactate levels, both did neither correlate with β2-microglobulin nor with ACE. Both CSF β2-microglobulin and ACE deserve further investigation as biomarkers of multiple sclerosis pathophysiology. Graphical abstract Unlabelled Image Highlights • CSF levels of β2-microglobulin, lactate and ACE significantly increase with age • Age-adjusted CSF β2-microglobulin and lactate are higher, while ACE is lower in multiple sclerosis patients than controls • Only lactate but not β2-microglobulin nor ACE correlates with MS disease duration and severity • CSF β2-microglobulin and ACE deserve further investigation as biomarkers of multiple sclerosis pathophysiology [ABSTRACT FROM AUTHOR]

Molecularly imprinted polymers (MIPs) for protein recognition have great application potential in the biological analysis. However, preparation of protein imprinted polymer is still facing challenge. Beta2-microglobulin (β 2 m) is a protein biomarker that can be used in diagnosis of different diseases. In this research, a novel MIP with ability of β 2 m recognition has been developed by epitope and surface-confined imprinting approaches. A peptide with sequence of MIQRTPKIQ was selected as template. A strategy of combination of hierarchical imprinting and template immobilization was employed in the β 2 m-MIP synthesis. Imprinted binding sites with open-entrance have been created that have good accessibility for β 2 m and facilitated fast reversible binding kinetics. The experimental results demonstrated that the MIP has good selectivity. It can differentiate the template from peptide with different sequence and distinguish the β 2 m from other proteins with similar size and pI values. After binding property study of the β 2 m-MIP, a method of β 2 m determination in serum was established in which β 2 m was on-line extracted by MIP and analyzed by HPLC process. The recoveries for spiked serum was ≥83% with RSD <1.1%, indicating that the method has good accuracy and precisions. The LOD and LOQ were 0.058 and 0.195 mg L −1 respectively, which meet the requirements of the β 2 m analysis. The successful application of the β 2 m-MIP demonstrated that β 2 m has reversible binding on the MIP with a kinetics that can meet the requirements of the HPLC analysis. It also indicated that the β 2 m-MIP has good mechanical strength and reusability that can be applied reliably in the practical analysis. As a synthetic antibody, β 2 m-MIP is advantageous compared to the biological molecules. [ABSTRACT FROM AUTHOR]

Systemic sclerosis (SSc) is a chronic autoimmune connective tissue disease. Humoral immunity and B cells are thought to play an important role in the pathophysiology of the disease. B cells are activated, produce specific autoantibodies and profibrotic cytokines. One way to assess B cell activation is to measure serum free light chains of immunoglobulins (sFLC) levels. We assess here sFLC levels in patients with systemic sclerosis (SSc) and their correlation with the disease characteristics, activity and severity. One hundred and thirty-four SSc patients were prospectively enrolled and compared to 401 age- and sex-matched healthy controls. sFLC levels were measured by a new quantitative immunoassay. sFLC levels were significantly higher in SSc patients than in healthy controls. sFLC levels correlated with modified Rodnan skin score and were independently associated with the presence of interstitial lung disease and its severity. In univariate analysis, sFLC levels correlated with SSc activity, as measured by the European Scleroderma Study Group activity index, and severity, as measured by the Medsger's total severity score. In multivariate analysis, beta2-microglobulin levels correlated with disease activity, BAFF levels with severity and sFLC with neither of these. Other B-cell activation biomarkers (IgG, IgA, beta2-microglobulin and BAFF) were independently correlated with sFLC. sFLC levels are elevated in SSc and are independently associated with lung disease and its severity. B-cell activation biomarkers, including sFLC, beta2-microglobulin and BAFF, correlate with disease severity and activity. These results further support the role of B cell activation in the pathophysiology of SSc. [ABSTRACT FROM AUTHOR]

Highlights: [•] AGEs of β2-m were identified and characterized in in vitro conditions. [•] Carboxymethyl, carboxyethyl and methyl-imidazolinone Arg3 were identified in β2-m isolated from the urine of uremic subjects. [•] AGEs content of urinary β2-m were found to range from 0.2 to 1% in uremic subjects. [Copyright &y& Elsevier]

Abstract: In this work we present for the first time the use of ion-exchange liquid chromatography to separate the native form and a partially structured intermediate of the folding of the amyloidogenic protein beta2-microglobulin. Using a strong anion-exchange column that accounts for the differences in charge exposure of the two conformers, a LC–UV method is initially optimised in terms of mobile phase pH, composition and temperature. The preferred mobile phase conditions that afford useful information were found to be 35mM ammonium formate, pH 7.4 at 25°C. The dynamic equilibrium of the two species is demonstrated upon increasing the concentration of acetonitrile in the protein sample. Then, the chromatographic method is transferred to MS detection and the respective charge state distributions of the separated conformers are identified. The LC–MS results demonstrate that one of the conformers is partially unfolded, compared with the native and more compact species. The correspondence with previous results obtained in free solution by capillary electrophoresis suggest that strong ion exchange LC–MS does not alter beta2-microglobulin conformation and maintains the dynamic equilibrium already observed between the native protein and its folding intermediate. [Copyright &y& Elsevier]

Abstract: Decay accelerating factor (DAF, CD55) is used by DAF-dependent (Daf+) variants of echovirus 11 (EV11) as a primary cellular receptor. The interaction of EV11 with DAF is completely reversible, therefore DAF-dependent variants require an unidentified coreceptor to initiate uncoating. Daf− variants of EV11, which do not interact with DAF, use an alternative primary cellular receptor. The aim of this study was to test the hypothesis whether the coreceptor, which is necessary for the uncoating of DAF-dependent variants, may act as an alternative primary receptor for the Daf− variants of EV11. By using the model of the two closely related daf+ and daf− clones of EV11 in rhabdomyosarcoma (RD) cell line, it was shown that a single amino acid substitution in the capsid protein VP2 could control the expression of the DAF-dependent phenotype. Anti-DAF monoclonal antibody has blocked the infection of RD cells by the DAF-dependent daf+ clone, but not by the daf− clone of EV11. Since the structural proteins of the two clones differed only in the receptor binding site for DAF, the unidentified non-DAF primary receptor for the daf− clone might have the same conformation as the uncoating coreceptor required for the daf+ clone. Despite the difference in primary receptors, both daf+ and daf− clones were equally inhibited by a monoclonal antibody to beta2-microglobulin. The monoclonal antibody B9.12.1 to class I human leukocyte antigen molecules showed no inhibitory effect in regards to either clone. The hypothesis of convergent intracellular traffic of Daf+ and Daf− variants of EV11 is discussed. [Copyright &y& Elsevier]

Abstract: There is increasing evidence that end-stage renal disease patients with lower beta2-microglobulin plasma levels and patients on convective renal replacement therapy are at lower mortality risk. Therefore, an enhanced beta2-microglobulin removal by renal replacement procedures has to be regarded as a contribution to a more adequate dialysis therapy. In contrast to high-flux dialysis, low-flux hemodialysis is not qualified to eliminate substantial amounts of beta2-microglobulin. In hemodialysis using modern high-flux dialysis membranes, a beta2-microglobulin removal similar to that obtained in hemofiltration or hemodiafiltration can be achieved. Several of these high-flux membranes are protein-leaking, making them suitable only for hemodialysis due to a high albumin loss when used in more convective therapy procedures. On-line hemodiafiltration infusing large substitution fluid volumes represents the most efficient and innovative renal replacement therapy form. To maximize beta2-microglobulin removal, modifications of this procedure have been proposed. These modifications ensure safer operating conditions, such as mixed hemodiafiltration, or control albumin loss at maximum purification from beta2-microglobulin, such as mid-dilution hemodiafiltration, push/pull hemodiafiltration or programmed filtration. Whether these innovative hemodiafiltration options will become accepted in clinical routine use needs to be proven in future. [Copyright &y& Elsevier]

Background. Beta2-microglobulin (β2-m) removal in patients with end-stage renal disease (ESRD) is maximal with convective techniques, such as hemofiltration (HF) or hemodiafiltration (HDF). Although the infusion mode of the replacement solution (predilution or postdilution) is expected to influence the efficiency of HF, experimental data in this respect are scanty. We therefore investigated the impact of the fluid reinfusion mode on the efficiency of HF in 11 ESRD patients who underwent both treatments. Methods. The dialyzer (AK 200 ULTRA) was equipped with a 3-layer polyamide membrane (Poliflux 21 S, surface 2.1 m2) and blood flow was kept between 300 and 400 mL/min. β2-m concentrations were measured in plasma water and ultrafiltrate at appropriate times during a 240-minute treatment. The following dialytic parameters were calculated: total amount of β2-m removed (Atot), β2-m removed by convection (Acon) and by adsorption (Aads), percent reduction in β2-m plasma water concentration (% Cpwin), total plasma water clearance (CLpwtot), convective plasma water clearance (CLpwcon), adsorptive plasma water clearance (CLpwads), and sieving coefficient (SC). Results. CLpwtot, CLpwads, and% Cpwin were similar in pre- and postdilutional conditions, whereas CLpwcon and SC were higher and CLpwads was lower in postdilution than in predilution HF. Since a significant inverse correlation was found between Aads and SC, predilution probably determines greater protein fouling than postdilution. Conclusion. The 2 techniques appear to be equivalent in terms of total β2-m removal, although this final result is obtained by different contributions of convective and adsorptive elimination. [ABSTRACT FROM AUTHOR]