Serum beta 2-microglobulin, sialic acid, and C-reactive protein in systemic lupus erythematosus

Assessment of kidney function using inulin-based and estimated glomerular filtration rates before and after allogeneic hematopoietic stem cell transplantation in pediatric patients

BACKGROUND

Accurate evaluation of kidney function before and after allogeneic hematopoietic stem cell transplantation (allo-HSCT) is important for both informed decision making and detection of chronic kidney disease. However, to the best of our knowledge, no report has evaluated the glomerular filtration rate (GFR) in pediatric patients who underwent HSCT using the gold standard GFR measurement, as well as inulin-based GFR (iGFR).

METHODS

We assessed iGFR before and after allo-HSCT to evaluate the impact of allo-HSCT on GFR in a prospective cohort study of 17 pediatric patients. We also assessed the accuracy and bias of the values of estimated GFR (eGFR) calculated using serum creatinine (Cr), cystatin C (CysC), beta-2 microglobulin (β₂ MG), 24-h creatinine clearance (24hCcr), and the full chronic kidney disease in children (CKiD) index that combines Cr, CysC, and blood urea nitrogen-based equations with iGFR as a reference to identify the most reliable equation for GFR.

RESULTS

There was no significant difference between the values before and after allo-HSCT. CKiD CysC-, 24hCcr-, and full CKiD-based values showed good within 30% (P30) accuracy (80.6%, 79.3%, and 80.6%, respectively), but only 24hCcr and full CKiD had good mean bias (8.5% and 8.9%, respectively) and narrow 95% limits of agreement (-32.2 to 52.7 mL/min/1.73 m² and -29.3 to 47.4 mL/min/1.73 m² , respectively) compared with the corresponding iGFR.

CONCLUSION

There was no significant impact of allo-HSCT on GFR in our cohort. The most reliable equations for pediatric patients with allo-HSCT were eGFR-24hCcr and eGFR-full CKiD.

Evaluation of the serum β2 Microglobulin level in patients with systemic lupus erythematosus and its correlation with disease activity

BACKGROUND

Designation of disease activity is serious for the management of systemic lupus erythematosus (SLE). Serum level of β2 microglobulin (β2M) may be associated with illness activity in SLE disease. Since the role of β2M for assessing of illness activity in SLE is not completely clear, the current study aimed to discern evaluation of β2M in patients with SLE and its correlation with sickness activity.

MATERIALS AND METHODS

In this case-control study, 50 patients with SLE disease and 25 healthy individuals were selected in Imam Khomeini Hospital in central of Urmia. Blood samples were collected safely from patients, serum was removed, and β2M measured using an ELISA method. The results for other parameters including C reactive protein, C3, C4, anti dsDNA and erythrocyte sedimentation rate were obtained from patients' medical record. Data analyzed using appropriate statistical tests including Mann-Whitney U test, Independent f-test, Kruskal-Wallis, and Spearman used for analysis of data.

RESULTS

In the current study, a significant difference was seen between two groups in terms of β2M (p < 0.001). Remarkable correlation was seen between the level of β2M with disease activity (p < 0.001). Furthermore, there are significant relevancy between the level of β2M with 24-hour urine protein, ESR, disease activity score, and CRP (p < 0.05).

CONCLUSION

The results revealed that serum amount of β2M in SLE patients is higher compared to healthy ones, which is significantly correlated to score of illness activity, CRP, and ESR in patients with SLE disease. Hence β2M might be an excellent serological marker helping the prediction of sickness activity and inflammation in SLE patients.

Pentraxins in the activation and regulation of innate immunity

Humoral fluid phase pattern recognition molecules (PRMs) are a key component of the activation and regulation of innate immunity. Humoral PRMs are diverse. We focused on the long pentraxin PTX3 as a paradigmatic example of fluid phase PRMs. PTX3 acts as a functional ancestor of antibodies and plays a non-redundant role in resistance against selected microbes in mouse and man and in the regulation of inflammation. This molecule interacts with complement components, thus modulating complement activation. In particular, PTX3 regulates complement-driven macrophage-mediated tumor progression, acting as an extrinsic oncosuppressor in preclinical models and selected human tumors. Evidence collected over the years suggests that PTX3 is a biomarker and potential therapeutic agent in humans, and pave the way to translation of this molecule into the clinic.

Predicting residual kidney function in hemodialysis patients using serum β-trace protein and β2-microglobulin

Residual kidney function (RKF) contributes significant solute clearance in hemodialysis patients. Kidney Diseases Outcomes Quality Initiative (KDOQI) guidelines suggest that hemodialysis dose can be safely reduced in those with residual urea clearance (KRU) of 2 ml/min/1.73 m(2) or more. However, serial measurement of RKF is cumbersome and requires regular interdialytic urine collections. Simpler methods for assessing RKF are needed. β-trace protein (βTP) and β2-microglobulin (β2M) have been proposed as alternative markers of RKF. We derived predictive equations to estimate glomerular filtration rate (GFR) and KRU based on serum βTP and β2M from 191 hemodialysis patients based on standard measurements of KRU and GFR (mean of urea and creatinine clearances) using interdialytic urine collections. These modeled equations were tested in a separate validation cohort of 40 patients. A prediction equation for GFR that includes both βTP and β2M provided a better estimate than either alone and contained the terms 1/βTP, 1/β2M, 1/serum creatinine, and a factor for gender. The equation for KRU contained the terms 1/βTP, 1/β2M, and a factor for ethnicity. Mean bias between predicted and measured GFR was 0.63 ml/min and 0.50 ml/min for KRU. There was substantial agreement between predicted and measured KRU at a cut-off level of 2 ml/min/1.73 m(2). Thus, equations involving βTP and β2M provide reasonable estimates of RKF and could potentially be used to identify those with KRU of 2 ml/min/1.73 m(2) or more to follow the KDOQI incremental hemodialysis algorithm.

Urine β2-microglobulin is associated with clinical disease activity and renal involvement in female patients with systemic lupus erythematosus

Objective

We investigated the association of serum and urine β2-microglobulin (β2MG) with renal involvement and clinical disease activity in systemic lupus erythematosus (SLE).

Methods

Sixty-four female patients with SLE were enrolled. We assessed SLE disease activity (SLEDAI)-2K and measured serum and urine β2MG levels, as well as complement (C3 and C4) and anti-dsDNA levels. According to the SLEDAI scores, two groups were categorized: low (0–5 of SLEDAI) and high (6–19 of SLEDAI) disease activity groups. The presence of renal involvement was determined by renal SLEDAI score. Statistical analysis was performed using Spearman’s correlation analysis, Mann-Whitney U test, multivariate regression analysis, and logistic regression analysis.

Results

Urine β2MG levels were significantly different between low and high SLEDAI groups ( p = 0.001), but not for serum β2MG levels ( p = 0.579). Patients with renal involvement showed higher urine β2MG levels compared to those without renal involvement ( p < 0.001), but again there was not a difference in serum β2MG levels ( p = 0.228). Urine β2MG was closely associated with SLEDAI ( r = 0.363, p = 0.003), renal SLEDAI ( r = 0.479, p < 0.001), urine protein/Cr ( r = 0.416, p = 0.001), and ESR ( r = 0.347, p = 0.006), but not serum β2MG ( r = 0.245, p = 0.051). Urine β2MG level was identified as a surrogate for renal involvement ( p = 0.009, OR = 1.017, 95% CI 1.004–1.030) and overall disease activity ( p = 0.009, OR = 1.020, 95% CI 1.005–1.036).

Conclusions

We demonstrated that urine β2MG levels are associated with renal involvement and overall clinical disease activity in SLE.

Sialic acid level reflects the disturbances of glycosylation and acute-phase reaction in rheumatic diseases

In the rheumatic diseases, the changes in the carbohydrate part of serum glycoproteins occur and these abnormalities can be monitored by serum level of total and free sialic acid. The aim of this study was to evaluate the total and free sialic acid level as a marker of inflammation activity (TSA) and the changes in glycosylation of blood glycoproteins (FSA) in rheumatoid arthritis (RA), systemic sclerosis (SSc) and systemic lupus erythematosus (SLE). Studies were carried out in 50 patients with RA, 24 with SLE and 32 with SSc. TSA concentration was measured with an enzymatic, colorimetric method and FSA with a thiobarbituric method. The serum levels of TSA in RA and SLE patients were significantly increased compared to controls and in RA patients were higher than that in SSc patients. The mean serum level of FSA in RA patients was significantly higher, but in SSc patients significantly lower than that in the controls, and in RA patients was significantly higher than in SLE and in SSc patients. All acute-phase proteins were changed: Positive acute-phase proteins were elevated, and the negative protein was decreased. The positive acute-phase proteins positively correlated with the levels of TSA and FSA in RA and SSc patients. In SLE patients, TSA positively correlated with haptoglobin and α1-antitrypsin. In RA patients, there was the positive correlation of TSA and FSA with DAS 28. The changes in the serum levels of TSA and FSA in the course of rheumatic diseases could reflect the abnormalities in glycosylation/sialylation patterns of glycoproteins induced by acute-phase response.

Comparison of serum concentrations of β-trace protein, β2-microglobulin, cystatin C, and creatinine in the US population

BACKGROUND AND OBJECTIVES

β-trace protein (βTP), β2-microglobulin (β2M), and cystatin C (CysC) have advantages over creatinine for estimating GFR and prognosis. This study compares the distribution of all four markers in the general population and their associations with possible determinants of GFR.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

βTP and β2M were measured in 7596 participants (aged ≥12 years) of the Third National Health and Nutrition Examination Survey (1988-1994). βTP and β2M concentrations and the proportion of persons with elevated (≥99th percentile for young healthy participants) βTP (≥0.81 mg/L), β2M (≥2.80 mg/L), standardized CysC (≥1.03 mg/L), and creatinine (≥1.2 mg/dl for men and ≥1.0 mg/dl for women) were compared across demographic and clinical factors.

RESULTS

Elevated βTP, β2M, and CysC showed stronger associations with age than elevated serum creatinine, the prevalence of elevated levels reaching 47%, 44%, 58%, and 26%, respectively, by age 80 years. βTP, CysC, and creatinine were higher in men but β2M was not associated with sex. Mexican Americans had lower βTP, β2M, CysC, and creatinine compared with non-Hispanic whites. Hypertension and higher C-reactive protein were associated with elevations in all markers, whereas non-Hispanic black race, body mass index, diabetes, smoking status, triglycerides, HDL cholesterol, and education were not associated in a consistent manner across the different markers.

CONCLUSIONS

βTP, β2M, CysC, and creatinine differ in their associations with demographic and clinical factors, suggesting variation in their non-GFR determinants. Future studies should examine these markers with measured GFR to determine their diagnostic and prognostic utility.

Beta 2-microglobulin can be a disease activity marker in systemic lupus erythematosus

BACKGROUND

To investigate the clinical significance of beta2-microglobulin in Korean patients with systemic lupus erythematosus (SLE).

METHODS

Blood samples were collected from patients with SLE (n = 100) and normal healthy controls (n = 50). The level of beta2-microglobulin was investigated by enzyme-linked immunosorbent assay. Serial samples from SLE patients were collected at 4.2 +/- 2.6 months after first sampling.

RESULTS

The beta2-microglobulin levels of the SLE patients (2.64 +/- 0.11 microg/mL) were higher than the normal controls (2.14 +/- 0.04 microg/mL, P < 0.001). The patients with SLE with serositis, oral ulcer, or lupus nephritis had significantly higher beta2-microglobulin levels than those without, respectively. A significant correlation was found between the beta2-microglobulin level and each of anti-dsDNA antibody, hemoglobin, complement, and SLE Disease Activity Index. In sequential sampling of patients with SLE, a positive correlation was found between the change of the SLE Disease Activity Index and the change of the beta2-microglobulin levels.

CONCLUSIONS

These data suggest that the measurement of beta2-microglobulin seem to be a useful addition to the laboratory tests that can help in assessment of disease activity of SLE.

Synthesis and turnover of beta2-microglobulin in Ad12-transformed cells defective in assembly and transport of class I major histocompatibility complex molecules

In primary embryonal fibroblasts from transgenic mice expressing H-2 genes and a miniature swine class I transgene (PD1), transformation with the highly oncogenic Ad12 results in a reduction in peptide transporter and proteasome-associated (LMP2 and LMP7) gene expression, and suppression in transport and cell surface expression of all class I antigens. The selective suppression in transport of H-2 (but not of PD1) molecules in cells reconstituted for the expression of peptide transporter and LMP genes implied that an additional factor(s) is involved in the assembly of class I complexes. Here we show that the beta2m, H-2Db, and H-2Kb genes are transcribed and translated in Ad12-transformed cells. However, unlike normal and E1Ad5-transformed cells, in which beta2m is either secreted unbound or bound to class I heavy chains, in Ad12-transformed cells significant amounts of beta2m are retained in the cell bound to the membrane, but free of class I heavy chains. This abnormal turnover of beta2m in the Ad12-transformed cells suggests the existence of a novel beta2m-binding molecule(s) that sequesters beta2m, and this process may provide a mechanism by which transformation with Ad12 may subvert class I complex formation.

Serum beta 2-microglobulin in intravenous drug users and its correlation with human immunodeficiency virus infection

High levels of serum beta 2-microglobulin have been associated with human immunodeficiency virus infection and beta 2-microglobulin has been used with other serological and immunological markers for monitoring disease progression. The usefulness of beta 2-microglobulin as a prognostic marker during human immunodeficiency virus infection has been demonstrated in homosexual men and hemophiliacs; few and contradictory data have been reported in intravenous drug users. We have evaluated a cohort of 160 intravenous drug users (81 seronegative and 79 seropositive for human immunodeficiency virus infection) with normal renal function to assess whether serum beta 2-microglobulin could be used as a serological marker for monitoring infection; 78 healthy subjects were used as controls. Of 79 seropositive drug users, 54 were asymptomatic or had persistent generalized lymphoadenopathy the remaining 25 had the acquired immunodeficiency syndrome. Seropositive patients were tested for CD4+ lymphocyte number, p24 antigen and anti-p24 antibodies. A significant statistical difference was found in mean serum beta 2-microglobulin levels between seronegative and seropositive drug users. Moreover, higher levels of beta 2-microglobulin were observed in acquired immunodeficiency syndrome patients compared with asymptomatic or patients with persistent lymphadenopathy. A significant relationship was also observed between increased concentration of beta 2-microglobulin and the serological and immunological markers which indicate human immunodeficiency virus disease progression.

Different lymphoid cell populations produce varied levels of neopterin, beta 2-microglobulin and soluble IL-2 receptor when stimulated with IL-2, interferon-gamma or tumour necrosis factor-alpha

Immune activation is central to many immune disorders. Clinical investigations have shown that immune activation can be quantified by measurements of soluble immune activation products in serum. Most in vitro studies of these immune activation products have focused on single products. In this study the specific cell sources and the major lymphokines inducing multiple activation products were investigated. In vitro addition of interferon-gamma (IFN-gamma) or IL-2 stimulated peripheral blood mononuclear cells to produce neopterin, beta 2-microglobulin (beta 2-M) and soluble IL-2 receptor (sIL-2R). These two lymphokines can act independently, because neutralizing antibodies to one of the lymphokines did not block the inducing activity of the other. Tumour necrosis factor-alpha (TNF-alpha) was also investigated and shown to be a less powerful inducer than IL-2 or INF-gamma. Separated lymphoid subpopulations responded differently to specific lymphokines. Monocytes produced only neopterin and only in response to INF-gamma. T cells released beta 2-M and sIL-2R in response to IL-2. B cells, however, were capable of producing all three immune activation products. Neopterin production in B cells was induced by either INF-gamma of IL-2, indicating that B cells have additional mechanisms for responding to lymphokines. To investigate whether these in vitro findings also occur in vivo, sera from patients who had received either rIL-2 or INF-gamma treatment were tested. INF-gamma administration led to substantial increases in serum neopterin but only a moderate beta 2-M increase and no increase in the serum sIL-2R levels. rIL-2 administration caused a substantial increase of all three serum immune activation products, consistent with our in vitro findings. The results confirm that increased serum levels of soluble immune activation products are indicators of increased cytokine production by lymphocytes and monocytes and also that B cells can be a prominent source of immune activation products.

beta 2-Microglobulin amyloidosis. A systemic amyloid disease affecting primarily synovium and bone in long-term dialysis patients

A number of rheumatic disorders occur in patients on long-term hemodialysis treatment. In recent years a clinical syndrome comprising carpal tunnel syndrome, destructive arthropathy, and cystic bone lesions has been recognized in these patients. Congo-red staining and microscopy in polarized light reveal a high frequency of amyloid in the affected tissues. Amino acid sequence data of the isolated major amyloid fibril protein show its identity with beta 2-microglobulin. beta 2-microglobulin amyloid has a predilection for synovial tissues and bone, but visceral deposits may also occur indicating the systemic nature of the disease. The clinicopathological features, pathogenesis, and diagnosis of beta 2-microglobulin amyloidosis are reviewed, and the therapeutic and prophylactic measures discussed. The identification of beta 2-microglobulin as an amyloidogenic protein has in an important way contributed to the understanding of the mechanisms of amyloidogenesis in general and emphasized the complexity of amyloid disease and the diversity of proteins capable of forming congophilic fibrillar deposits in human tissues.

Significance and limits of cerebrospinal fluid beta-2-microglobulin measurement in course of acute lymphoblastic leukemia

Cerebrospinal fluid beta-2-microglobulin (CSF-beta 2m) was measured longitudinally in 48 patients affected by acute lymphoblastic leukemia (ALL). Thirteen developed a central nervous system (CNS) involvement during the course of the disease; although moderately higher mean CSF-beta 2m levels were found in these subjects, no significant statistical differences were observed in comparison with patients without this complication and compared with the control group. No correlations were found between beta 2m and other biochemical parameters in CSF. Furthermore, CSF-beta 2m levels appeared to be influenced by previous combined chemoradiotherapeutic treatment for CNS prophylaxis, presence of meningeal non-neoplastic infiltrates, patients' ages, amount of CSF blasts, and their immunological phenotype. In particular, only clearly B-committed leukemic cells, when tested, showed a strong surface expression of beta 2m, as demonstrated by immunocytochemical detection of this protein on cell membrane. However, in specific cases, CSF beta 2m measurement and CSF/serum beta 2m ratio were helpful in diagnosing and monitoring isolated CNS disease. Such findings suggest that CSF-beta 2m assay may be a useful tool in the management of CNS involvement in the course of ALL in only selected patients, as several factors can modify the outcome.

Serum beta 2-microglobulin as a marker of activity in systemic lupus erythematosus

A prospective study of 62 patients with systemic lupus erythematosus (SLE) was performed in order to establish whether serum beta 2m could be a good marker of clinical activity. beta 2m was determined by radio-immunoassay and the values compared with a control group of healthy individuals. The mean value of beta 2m in the control group was 1.48 +/- 0.52 mg/l and 2.87 +/- 2.19 mg/l (p less than 0.001) in the SLE group, 4.53 +/- 2.89 mg/l in the 22 patients with active disease and 2.40 +/- 1.80 mg/l (p less than 0.001) in the 40 patients with inactive disease. High beta 2m values (greater than or equal to 3 mg/l) were observed in 64% of the patients with active SLE, VS. only 12% of the patients with inactive disease (p less than 0.001). Significant differences were also observed when beta 2m of the patients with inactive SLE was compared with the control group (p less than 0.001). The beta 2m with a sensitivity of 64%, a specificity of 87%, and an efficiency of 79% could be a good parameter to detect SLE clinical activity.

Atrophic gastritis in Sjögren's syndrome. Morphologic, biochemical, and immunologic findings

Gastric studies were carried out in 16 patients with well-documented Sjögren's syndrome (SS), 43 matched rheumatic disease patients without SS, and 7 patients with chronic atrophic gastritis not associated with SS. Chronic atrophic gastritis was a much more common finding in the SS patients than in the rheumatic disease control patients. Significant hypopepsinogenemia was present in 11 of 16 SS patients. In 6 patients this was combined with hypergastrinemia, a combination highly specific for chronic atrophic gastritis. The lowest pepsinogen levels were seen in patients with primary SS associated with high levels of SS-B antibody. On a histologic and biochemical basis, it was not possible to distinguish the gastric findings in primary SS from those in secondary SS, nor to distinguish chronic atrophic gastritis associated with SS from that not associated with SS. We conclude that chronic atrophic gastritis is a prominent feature in SS and that the severity of the gastritis appears to correlate with some serologic parameters of SS.