Urine neopterin as a parameter of disease activity in patients with systemic lupus erythematosus: comparisons with serum sIL-2R and antibodies to dsDNA, erythrocyte sedimentation rate, and plasma C3, C4, and C3 degradation products

A systematic review and meta-analysis of neopterin in rheumatic diseases

Introduction

Novel biomarkers of inflammation and oxidative stress might enhance the early recognition, management, and clinical outcomes of patients with rheumatic diseases (RDs). We assessed the available evidence regarding the pathophysiological role of neopterin, the oxidation product of 7,8-dihydroneopterin, a pteridine generated in macrophages activated by interferon-γ, by conducting a systematic review and meta-analysis of studies reporting its concentrations in biological fluids in RD patients and healthy controls.

Methods

We searched electronic databases for relevant articles published between inception and 31 August 2023. The risk of bias and the certainty of evidence were assessed using the Joanna Briggs Institute Critical Appraisal Checklist and the Grades of Recommendation, Assessment, Development and Evaluation Working Group system, respectively.

Results

In 37 studies, when compared to healthy controls, RD patients had significantly higher concentrations of neopterin both in plasma or serum (standard mean difference, SMD=1.31, 95% CI 1.01 to 1.61; p<0.001; moderate certainty of evidence) and in the urine (SMD=1.65, 95% CI 0.86 to 2.43, p<0.001; I2 = 94.2%, p<0.001; low certainty of evidence). The results were stable in sensitivity analysis. There were non-significant associations in meta-regression and subgroup analysis between the effect size and age, male to female ratio, year of publication, sample size, RD duration, C-reactive protein, erythrocyte sedimentation rate, specific type of RD, presence of connective tissue disease, analytical method used, or biological matrix investigated (plasma vs. serum). By contrast, the effect size was significantly associated with the geographical area in studies assessing serum or plasma and with the type of RD in studies assessing urine.

Discussion

Pending additional studies that also focus on early forms of disease, our systematic review and meta-analysis supports the proposition that neopterin, a biomarker of inflammation and oxidative stress, can be useful for the identification of RDs. (PROSPERO registration number: CRD42023450209).

Systematic review registration

PROSPERO, identifier CRD42023450209.

Targeting interferon-γ in hyperinflammation: opportunities and challenges

Interferon-γ (IFNγ) is a pleiotropic cytokine with multiple effects on the inflammatory response and on innate and adaptive immunity. Overproduction of IFNγ underlies several, potentially fatal, hyperinflammatory or immune-mediated diseases. Several data from animal models and/or from translational research in patients point to a role of IFNγ in hyperinflammatory diseases, such as primary haemophagocytic lymphohistiocytosis, various forms of secondary haemophagocytic lymphohistiocytosis, including macrophage activation syndrome, and cytokine release syndrome, all of which are often managed by rheumatologists or in consultation with rheumatologists. Given the effects of IFNγ on B cells and T follicular helper cells, a role for IFNγ in systemic lupus erythematosus pathogenesis is emerging. To improve our understanding of the role of IFNγ in human disease, IFNγ-related biomarkers that are relevant for the management of hyperinflammatory diseases are progressively being identified and studied, especially because circulating levels of IFNγ do not always reflect its overproduction in tissue. These biomarkers include STAT1 (specifically the phosphorylated form), neopterin and the chemokine CXCL9. IFNγ-neutralizing agents have shown efficacy in the treatment of primary haemophagocytic lymphohistiocytosis in clinical trials and initial promising results have been obtained in various forms of secondary haemophagocytic lymphohistiocytosis, including macrophage activation syndrome. In clinical practice, there is a growing body of evidence supporting the usefulness of circulating CXCL9 levels as a biomarker reflecting IFNγ production.

Neopterin serum level does not reflect the disease activity in rheumatoid arthritis: A systematic review and meta-analysis

Rheumatoid arthritis (RA) is a chronic autoimmune disease caused by established chronic inflammation. Neopterin levels have extensively been considered as a marker of immune activation during inflammation. In this study, we performed a systematic evaluation and meta-analysis to elucidate the overall relationship between neopterin concentration and RA disease activity. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines, a systematic review was conducted using PubMed, Google Scholar, Web of Science, and Scopus from 2000 to August 2020. The Newcastle-Ottawa scale was used to assess the quality of eligible studies. The effect size (ES) and corresponding 95% confidence intervals (CIs) were calculated to evaluate this association. A total of 15 studies out of 98 met our inclusion criteria. The pooled analysis found that patients with RA had high level of neopterin; however, no statistically significant association was found between neopterin levels with high, intermediate, and low diseases activity score (DAS)-28 (ES =11.18, 95% CI: 6.02 to 16.34, and I² = 91.8%; and ES = 8.57, 95% CI: 6.41 to 10.37, and I² = 99.5%; and ES =12.45, 95% CI: -1.68 to 26.58, and I² = 99.0%, respectively). Our results indicated that the neopterin concentration does not seem to have any substantial impact on the RA disease activity.

Anti-CD22 epratuzumab for systemic lupus erythematosus: A systematic review and meta-analysis of randomized controlled trials

Systemic lupus erythematosus (SLE) is a remarkable and challenging autoimmune disorder that is characterized by a broad range of clinical manifestations, such as flares and remissions. Recently, the humanized anti-CD22 antibody epratuzumab for SLE has been extensively studied. The aim of the present study was to perform a meta-analysis on the findings of associated randomized controlled trials in order to evaluate the effects of epratuzumab on SLE. Data from publications in PubMed, EMBASE and the Cochrane Library were collected up to March 2017. To calculate the risk ratio or standardized mean differences (SMDs) with 95% confidence intervals (CIs), a random effect model was applied when heterogeneity was significant and a fixed effect model was used when heterogeneity was negligible. All statistical tests were performed using Review Manager 5.3 software. A total of 1,921 participants in 4 studies (5 trials) that met the selection criteria were analyzed in this meta-analysis. Analyses of the BILAG-based Combined Lupus Assessment (BICLA) response and SLE Disease Activity Index 2000 (SLEDA-2K) score revealed that epratuzumab (720-3,600 mg) significantly improved the BICLA response (RR=1.09; 95% CI, 1.04 to 1.14) and decreased the SLEDA-2K score (SMD=-0.31; 95% CI, -0.67 to 0.06; P=0.10). While the British Isles Lupus Assessment Group index score was not significantly altered between the epratuzumab and control groups. For safety analyses, no statistically significant differences were identified between the two groups, which were proved by the pooled results (all P-values >0.05). These findings suggested that epratuzumab may be relatively safe and may have better therapeutic effectiveness than placebo control conditions in patients with SLE.

Protective Effects of Hydroxychloroquine against Accelerated Atherosclerosis in Systemic Lupus Erythematosus

Cardiovascular (CV) morbidity and mortality are a challenge in management of patients with systemic lupus erythematosus (SLE). Higher risk of CV disease in SLE patients is mostly related to accelerated atherosclerosis. Nevertheless, high prevalence of traditional cardiovascular risk factors in SLE patients does not fully explain the increased CV risk. Despite the pathological bases of accelerated atherosclerosis are not fully understood, it is thought that this process is driven by the complex interplay between SLE and atherosclerosis pathogenesis. Hydroxychloroquine (HCQ) is a cornerstone in treatment of SLE patients and has been thought to exert a broad spectrum of beneficial effects on disease activity, prevention of damage accrual, and mortality. Furthermore, HCQ is thought to protect against accelerated atherosclerosis targeting toll-like receptor signaling, cytokine production, T-cell and monocyte activation, oxidative stress, and endothelial dysfunction. HCQ was also described to have beneficial effects on traditional CV risk factors, such as dyslipidemia and diabetes. In conclusion, despite lacking randomized controlled trials unambiguously proving the protection of HCQ against accelerated atherosclerosis and incidence of CV events in SLE patients, evidence analyzed in this review is in favor of its beneficial effect.

Safety, pharmacokinetics and pharmacodynamics of AMG 811, an anti-interferon-γ monoclonal antibody, in SLE subjects without or with lupus nephritis

OBJECTIVE

To evaluate safety, pharmacokinetics and pharmacodynamics of anti-interferon (IFN)-γ monoclonal antibody AMG 811 in subjects with SLE without or with lupus nephritis (LN).

METHODS

In this phase Ib, randomised, multiple-dose escalation study (NCT00818948), subjects without LN were randomised to subcutaneous AMG 811 (6, 20 or 60 mg) or placebo and subjects with LN were randomised to subcutaneous AMG 811 (20, 60 or 120 mg) or placebo every four weeks for three total doses. Outcomes included incidence of adverse events (AEs); pharmacokinetics; levels of serum proteins (CXCL-10, interleukin 18, monocyte chemotactic protein-1); changes in gene transcript profiles and clinical parameters (Safety of Estrogen in Lupus Erythematosus National Assessment-Systemic Lupus Erythematosus Disease Activity Index (SELENA-SLEDAI) scores, proteinuria, anti-double-stranded DNA (anti-dsDNA) antibodies, C3 complement, C4 complement).

RESULTS

Fifty-six subjects enrolled (28 SLE without LN; 28 with LN). Baseline mean SELENA-SLEDAI scores were 2.2 and 12.0 for SLE subjects without and with LN, respectively. Most subjects reported an AE; no meaningful imbalances were observed between AMG 811 and placebo. Pharmacokinetic profiles were similar and mostly dose-proportional in subjects without or with LN. AMG 811 treatment reduced CXCL-10 protein levels and blood-based RNA IFN-γ Blockade Signature compared with placebo. Reductions were less pronounced and not sustained in subjects with LN, even at the highest dose tested, compared with subjects without LN. No effect on SELENA-SLEDAI scores, proteinuria, C3 or C4 complement levels, or anti-dsDNA antibodies was observed.

CONCLUSION

AMG 811 demonstrated favourable pharmacokinetics and acceptable safety profile but no evidence of clinical impact. IFN-γ-associated biomarkers decreased with AMG 811; effects were less pronounced and not sustained in LN subjects.

TRIAL REGISTRATION NUMBER

NCT00818948; results.

Determination of six pterins in urine by LC-MS/MS

BACKGROUND

The present work describes an analytical method for urinary pterins by LC-MS/MS, with emphasis on the separation of 6- and 7-positional isomers of bio- and neopterins.

RESULTS

Urine sample preparation consisted of oxidation by MnO(2), filtration and direct dilution in the mobile phase. The method was validated in urine spiked at five concentration levels with true triplicates of each level. Separation of the pterins, including the positional isomers, was achieved by employing a LUNA amino column. Six pterins were quantified (pterin, isoxanthopterin, 6-biopterin, 7-biopterin, 6-neopterin, 7-neopterin) and a linear behavior was observed; LOD varied from 7 to 360 pg/ml and correlation coefficients above 0.98 were obtained for all pterins. In addition, pterin levels were evaluated in 41 urine samples of healthy subjects, in ten urine samples of patients with classical phenylketonuria (PKU) and in one with atypical PKU.

CONCLUSION

The proposed method allowed to identify, separate and quantify six pterins in urine, using a simple and rapid sample preparation. The atypical PKU was unequivocally differentiated from the classical form, demonstrating that this method could be very useful for characterization and follow-up of diseases.

Macrophage activation and coronary atherosclerosis in systemic lupus erythematosus and rheumatoid arthritis

OBJECTIVE

Activation of macrophages may contribute to increased atherosclerosis and coronary artery disease in systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). Neopterin, a pteridine derivative, is a novel marker of monocyte and macrophage activation that is associated with atherosclerosis and cardiovascular risk in the general population. We examined the hypothesis that macrophage activation is associated with accelerated atherosclerosis in SLE and RA.

METHODS

We compared serum neopterin concentrations, adjusted for age, race, sex, and serum creatinine concentration, in patients with SLE (n=148) or RA (n=166) and control subjects (n=177). In patients with SLE or RA, serum neopterin concentrations were then tested for association (adjusted for age, race, sex, serum creatinine, and medication use) with measures of disease activity or damage, inflammatory markers and mediators, and coronary artery calcium measured by electron beam computed tomography.

RESULTS

Neopterin concentrations were significantly higher in patients with SLE (median 8.0, interquartile range [IQR] 6.5-9.8 nmoles/liter) and RA (median 6.7, IQR 5.3-8.9 nmoles/liter) than controls (median 5.7, IQR 4.8-7.1 nmoles/liter), and were higher in SLE patients than in RA patients (all P<0.001). In SLE, neopterin was significantly correlated with higher erythrocyte sedimentation rate (ESR; P=0.001), tumor necrosis factor α (P<0.001), monocyte chemoattractant protein 1 (P=0.005), and homocysteine concentrations (P=0.01), but in RA, it was only associated with ESR (P=0.01). Neopterin was not associated with coronary calcium in either SLE (P=0.65) or RA (P=0.21).

CONCLUSION

Macrophage activation, reflected by increased serum neopterin concentrations, was increased in both SLE and RA. Neopterin was more robustly associated with atherogenic mediators of inflammation and homocysteine in SLE than in RA, but was not associated with coronary atherosclerosis in either disease.

Neopterin in HIV-1 infection

Neopterin is well established as a reliable marker in HIV-1 infection. Neopterin concentrations measured in urine or serum indicate sensitively the course and progression of the disease as well as efficacy of anti-retroviral therapy. The main trigger for neopterin production is Th1-type cytokine interferon-gamma. During acute HIV-1 infection, enhanced formation of neopterin occurs already at a very early time point, before antibody seroconversion takes place. After this stage, neopterin concentrations in serum and urine closely correlate with virus load in the circulation of HIV-1-infected patients. Data provide evidence for an important role of immune activation and Th1-type cytokine interferon-gamma in the pathogenesis of HIV-1 infection. This review subsumes the importance of neopterin as a marker in HIV-1 infection. Further evidence is increasing, that neopterin derivatives might modulate immune response by interfering with the cellular redox balance, activating redox-sensitive transcription factors, or inducing apoptosis in specific cell types. The possible impact of neopterin derivatives and of other biochemical pathways induced by interferon-gamma such as indoleamine 2,3-dioxygenase in chronic diseases like HIV-1 infection is discussed.

Urinary neopterin quantification by reverse-phase high-performance liquid chromatography with ultraviolet detection

Neopterin plays an important role in the malignant disease diagnostics. However, the methods employed in neopterin determination are generally difficult and/or time consuming. The aim of this work was to standardize a practical method to quantify neopterin using high-performance liquid chromatography-ultraviolet (HPLC-UV) and quantify it in patients with systemic lupus erythematosus (SLE). Urine was collected from healthy subjects (n= 49), patients with inactive (n= 15), active (n= 28), and highly active SLE (n= 6). The HPLC was performed using two coupled reverse-phase columns eluted with 150 mM sodium phosphate, pH 4.0, under a flow rate of 0.8 ml/min, with UV detector set at 353 nm and 100-fold diluted urines. The inter- and intra-assay studies presented an imprecision of 12.5% and 12.9% for quality controls of 3.94 and 1.1 micromol/ml, respectively. Recovery from 79.5% to 82% was observed throughout the assay's linear range. Subjects with active (874.2 +/- 165.38 micromol/mol creatinin) and highly active SLE (1753.8 +/- 453.9 micromol/mol creatinin) showed three- and sixfold increased neopterin levels, respectively, compared to subjects with inactive SLE (314.3 +/- 121.3 micromol/mol creatinin) and healthy subjects (294.6 +/- 178.6 micromol/mol creatinin) (P< 0.05). Briefly, the proposed method was precise, specific, and reproducible, not invasive and allows the urinary neopterin quantification only with UV detection.

Daily psychosocial stressors and cyclic response patterns in urine cortisol and neopterin in a patient with systemic lupus erythematosus

This study investigated the complex biochemical responses to personally meaningful everyday stressors in a patient with systemic lupus erythematosus (SLE). For this purpose, a 52 year-old woman with SLE collected her entire urine for 56 days on a 12-h basis for the determination of cortisol as well as neopterin, a cellular immune parameter. Additionally, using questionnaires, daily notes and interviews, extensive psychosocial and psychological time-series data were collected every 12 h. Cross-correlational analyses of the resulting time-series revealed that stressful incidents were associated with cyclic fluctuations in both urine cortisol and urine neopterin. Specifically, whenever the patient anticipated a moderately stressful incident, urine cortisol initially increased 24 h before the incident and then decreased 12 h before the incident. Moderate stressors not anticipated by the patient were associated with an initial increase 24 h following the incident and then with a decrease after a total of 36 h. Moreover, stressors having to do with the patient's extramarital relationship were followed initially by a decrease in urine neopterin after 36 h and then by an increase after a total of 60 h. Our findings indicate that when investigating the relationship between psychosocial stressors and biochemical activity in SLE, appropriate consideration of the data's dynamic nature may be necessary to avoid flawed conclusions.

[The influence of daily psychosocial stressors and associated emotions on the dynamic course of urine cortisol and urine neopterin in systemic lupus erythematosus: Experience taken from two "integrative single-case studies"]

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by flare-ups, the cause of which is unknown. According to new stress concepts, two "integrative single-case studies" have been conducted in order to gather evidence about whether daily stressful incidents and associated emotions interfere with the dynamics of urine cortisol and urine neopterin in SLE. Patients under study collected their urine at home, for a period of at least 50 days, on a daily basis, divided into day and night urine. Additionally, patients filled out questionnaires twice a day to determine their emotional state, life style and disease activity. Each week, patients were examined clinically and interviewed to identify the past week's stressors using the Incidents and Hassles Inventory (IHI, Brown and Harris). Statistical analysis of the serial data was performed using time-series analysis according to Box and Jenkins. In both "integrative single-case studies" we were able to demonstrate that stressful incidents predicted an increase in urine neopterin 36 hours (Case 1) to 60 hours (Case 2) later (p < 0.05). Additionally, in Case 1 the neopterin levels were highly associated with stress resulting from the weekly examinations and interviews. Furthermore, in Case 2 it turned out that depending on their predictability stressful incidents were preceded by a decrease in urine cortisol 12 hours earlier or were followed by a decrease in urine cortisol 36 hours later. And finally, emotional irritation was highly correlated with the course of urine-neopterin. In Case 2 irritation led to an increase in urine neopterin 84 hours later. There were no clinical signs of SLE during both prospective studies. In conclusion, our results validate the idea of "integrative single-case studies" as a new "bio-psycho-social" approach in psychoneuroimmunology. Further studies with SLE patients as well as with healthy probands will be necessary in order to both strengthen and generalize these results.

Degradation of tryptophan in patients with systemic lupus erythematosus

Systemic lupus erythematosus (SLE), a progressive autoimmune disorder, is associated with chronic stimulation of various components of the immune system. Since cell-mediated immunity is also activated, we were interested to test for abnormalities in tryptophan metabolism in SLE which may result from activation of indoleamine 2,3-dioxygenase by cytokines released during the immune response. We measured serum tryptophan and kynurenine concentrations in 52 patients with SLE as well as serum neopterin as an indicator for the degree of immune activation. Compared to controls, we found significantly decreased tryptophan and increased kynurenine concentrations in SLE. The extent of tryptophan catabolism correlates with neopterin concentrations or with the disease activity index. Tryptophan depletion may be associated with neurologic/psychiatric disturbances in patients suffering from SLE.

Enhanced tryptophan degradation in systemic lupus erythematosus

In vitro and in vivo, tryptophan degradation was found to be associated with T cell functional loss and tolerance induction. In systemic lupus erythematosus (SLE) besides the Th2-type cytokine interleukin-10, Th1-type cytokines including interferon-gamma (IFN-gamma) are expressed especially during exacerbation of the disease. IFN-gamma stimulates the enzyme indoleamine (2,3)-dioxygenase (IDO) converting tryptophan to the metabolite kynurenine which in macrophages is subsequently degraded to other, partly neurotoxic compounds like quinolinic acid, and finally to nicrotinamides. We measured kynurenine and tryptophan concentrations in the sera of 55 SLE patients. In these patients, the concentrations of tryptophan (median, interquartile range: 53.9, 45.7-64.1 microM) were lower (p < 0.0001), and the kynurenine concentrations (2.45, 1.75-3.40 microM) were increased (p < 0.0005) compared to healthy blood donors (70.0, 63.8-80.6; 1.80, 1.45-2.27 microM, respectively). Also the kynurenine per tryptophan quotients (K/T), which allow to estimate IDO activity, were significantly higher in patients than in normals (0.043, 0.033-0.062 vs. 0.027, 0.021-0.030; p < 0.0001), indicating enhanced IDO-induced tryptophan degradation in SLE. There was no significant relationship between tryptophan, kynurenine and the SLEDAI, and also the correlation of K/T with SLEDAI was rather weak (rs = 0.243, p < 0.05). Higher K/T was found in patients presenting with serositis (p = 0.01), decrease of complement (c3, c4; p < 0.01) and blood count change (anemia, leucopenia, lymphopenia; p = 0.032) than in patients without such disease manifestations. The significant correlation found between K/T and neopterin (rs = 0.808, p < 0.001), a marker of immune activation, points to a role of immune activation to be responsible for tryptophan degradation in SLE patients.

Daily psychosocial stressors interfere with the dynamics of urine neopterin in a patient with systemic lupus erythematosus: an integrative single-case study

OBJECTIVE

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by flare-ups, the causes of which are not known. In accordance with new concepts in stress research, this study investigated whether daily psychosocial stressors interfere with immunological processes in SLE. Because such processes are unique to each individual, single-case design using time-series analysis (Box and Jenkins) was applied.

METHODS

A 40-year-old woman with SLE (last flare-up September 1995) was interviewed initially to determine major life events and difficulties (using the Life Events and Difficulties Schedule) in the previous 2 years. She was then observed for 63 days. Urine neopterin, an immunological parameter demonstrated to parallel disease activity in SLE patients, was measured in daily overnight urine. Daily incidents were identified weekly by the Incidents and Hassles Inventory and independently rated. Intervening factors, including infections, medication, and lifestyle, were controlled.

RESULTS

Retrospectively, data obtained from the Life Events and Difficulties Schedule indicated that major life events and difficulties had preceded the patient's last flare-up in 1995. Although there were no clinical signs of SLE during this prospective study of 63 days, cross-correlational analyses revealed that "moderately" stressful incidents associated with higher levels of emotional irritation (lag 0: +0.271, p < .05) predicted an increase in urine neopterin the following day (lag 1: +0.441, p < .05). Moreover, a 7-day cyclicity in neopterin levels that corresponded to the weekly examinations and interviews was found.

CONCLUSIONS

This study showed a causal relationship between psychosocial stressors and urine neopterin concentrations that may be related to SLE disease activity. Furthermore, the workability of an integrative approach using single-case design and time-series analysis in psychoneuroimmunology was demonstrated for the first time.

Th1 and Th2 T helper cell subsets affect patterns of injury and outcomes in glomerulonephritis

The recognition that human immune responses can be directed by two different subsets of T helper cells (Th1 and Th2) has been an important development in modern immunology. Immune responses polarized by either the Th1 or Th2 subset predominance result in different inflammatory effector pathways and disease outcomes. Many autoimmune diseases are associated with either Th1- or Th2- polarized immune responses. Although these different immune response patterns are relevant to glomerulonephritis (GN), little attention has been paid to the consequences of Th1 or Th2 predominance of nephritogenic immune responses for the pattern and outcome of GN. Unlike other autoimmune conditions, GN results from a variety of different immune responses and has a range of histologic features and immune effectors in glomeruli. This review assesses the data available from studies of experimental and human GN that address the Th1 or Th2 predominance of nephritogenic immune responses and their relevance to the different histopathological patterns and outcomes of GN. In particular, the evidence that Th1-predominant nephritogenic immune responses are associated with severe proliferative and crescentic GN is presented.

Systemic lupus erythematosus in three ethnic groups: II. Features predictive of disease activity early in its course. LUMINA Study Group. Lupus in minority populations, nature versus nurture

OBJECTIVE

To determine the factors associated with disease activity in patients with recent-onset (< or =5 years) systemic lupus erythematosus (SLE) who were of Hispanic, African-American, or Caucasian ethnicity.

METHODS

Incident and prevalent cases of SLE, as defined by the American College of Rheumatology criteria for SLE, among the 3 ethnic groups were identified in Alabama (The University of Alabama at Birmingham) and Texas (The University of Texas-Houston Health Science Center and The University of Texas Medical Branch at Galveston). Variables from the sociodemographic, clinical, immunologic, immunogenetic, behavioral, and psychological domains were obtained using validated instruments. Disease activity was ascertained with the Systemic Lupus Activity Measure (SLAM). Stepwise domain regressions with SLAM score as the dependent variable were performed. Final ethnic-specific and overall regression models were obtained by entering variables that were retained in the domain regressions.

RESULTS

SLAM scores at study entry were higher in the African Americans (mean +/- SD 12.6 +/- 6.9) and Hispanics (11.0 +/- 6.2) than in the Caucasians (8.5 +/- 3.7) (P < or = 0.001). The final overall regression model (R2 = 28%) for higher SLAM score included the following variables: African-American ethnicity, lack of private health insurance, abrupt disease onset, presence of anti-Ro antibodies, absence of HLA-DRB1*0301, higher levels of helplessness, and abnormal illness-related behaviors.

CONCLUSION

Socioeconomic, immunologic, immunogenetic, behavioral, and psychological variables were all predictive of disease activity early in the course of SLE, irrespective of ethnic group. However, there remain ethnic group differences in disease activity that were not explained by these factors.

Correlation between CD29 density on CD8+ lymphocytes and serum IgG in systemic lupus erythematosus

The purpose of this paper is to establish whether there is increased lymphocyte adhesion molecule density in systemic lupus erythematosus (SLE), which could alter the migration pathways and activation thresholds of lymphocytes and thus contribute to the pathogenesis of the disease. We analysed the CD11a, CD29 and CD2 bound antibody molecule (bam) density on the CD4+ and CD8+ CAMhigh (primed) lymphocytes of 28 SLE patients (8 active and 20 inactive by BILAG), using reproducible flow cytometric measurements, standardized with fluorescent beads and antibodies of known fluorescein: protein ratios. In a second patient cohort (17 patients), we investigated whether CD29 density on CD8+ cells correlated with measures of humoral (serum IgG) or cellular (urine neopterin) activation. In the first cohort, 36% of patients had elevated CD29 (beta 1 integrin) density on CD8+ cells. In the second cohort, CD29 density on CD8+ cells was found to be closely associated with total plasma IgG (r = 0.71, P = 0.001), but not with urine neopterin, disease activity (BILAG) or drug treatment. We conclude that CD29 on CD8+ cells is associated with B cell activation in SLE.

Neopterin levels in alcohol-dependent patients

Chronic alcohol exposure appears to suppress cell-mediated immunity which may contribute to the high incidence of infections among alcohol-dependent patients. We measured serum neopterin, as a marker of macrophage function and T-lymphocyte activation, in 26 alcohol-dependent patients. The mean serum neopterin in these patients was significantly lower than the mean serum neopterin in matched controls. In those who abstained, the mean serum neopterin at 3 weeks rose and was no longer significantly different from controls. Our findings suggest that alcohol-dependent patients have suppressed macrophage function which may be reversible within 3 weeks of abstention.

Detection of immunodeficiencies and persistent infections by urinary neopterin measurement

We evaluated the clinical significance of measurement of urinary neopterin levels in primary immunodeficiencies and persistent infections exclusively at afebrile or asymptomatic periods. Despite the examinations at afebrile or asymptomatic periods, urinary neopterin levels were elevated in some patients with primary immunodeficiencies and in patients with persistent infections of human immunodeficiency virus (HIV) or Epstein-Barr virus (EBV). Therefore, urinary neopterin measurement at afebrile periods will be useful as one of the screening tests in the detection of such disorders among children with occasional episodes of infections.

Interferon-gamma and urine neopterin in attacks of the hyperimmunoglobulinaemia D and periodic fever syndrome

The hyperimmunoglobulinaemia D and periodic fever (hyper-IgD) syndrome is typified by recurrent unpredictable febrile attacks with abdominal pain, joint involvement (arthralgias/arthritis), headache, skin lesions and a polyclonal elevation of serum IgD (> 100 U mL-1). Interferon-gamma (IFN-gamma) is a major proinflammatory cytokine which could play a role in the pathogenesis of the attacks. There is a need for parameters (if possible non-invasive) to monitor disease activity. A potential candidate is neopterin which is released by monocytes/macrophages when stimulated with IFN-gamma, excreted unchanged in urine, and appears to be an early and sensitive marker for activation of the immune system. We measured rectal body temperature, serum IFN-gamma, and urine neopterin in 10 hyper-IgD patients both during and between attacks. The body temperature rose to a mean of 38.9 degrees C on the first day of the attack and normalized within 5 days. Serum IFN-gamma during the first day of the attack was 2.98 IU mL-1 and was significantly lower during remissions. The urine neopterin excretion was 268 +/- 170 mumol mol-1 creatinine between attacks and was significantly increased to 638 +/- 275 mumol mol-1 creatinine on the first day of symptoms. Maximal urine neopterin values were reached on the fourth day of the attack (1051 +/- 387 mumol mol-1 creatinine) and excretion gradually declined and attained values below 400 mumol mol-1 creatinine after 9 days. There was a good correlation between serum IFN-gamma and urine neopterin.(ABSTRACT TRUNCATED AT 250 WORDS)

Skeletal muscle lymphocytic vasculitis in systemic lupus erythematosus: relation to disease activity

Lymphocytic vasculitis (LV) characterises systemic lupus erythematosus (SLE) and this potentially reversible lesion, which may be subclinical, may imply overt systemic disease activity. Needle quadriceps muscle biopsy was performed in 26 unselected patients with SLE and the presence of LV in these muscle specimens was compared with SLE disease activity scored using the British Isles Lupus Assessment Group Index (BILAG). Ten of the 22 patients with active disease showed evidence of LV compared with none of the four patients with inactive disease. In the patient group with LV, significantly higher ESR and urine neopterin values were found with P = 0.002 and P = 0.02, respectively compared with patients without LV. Features of vasculitis (as defined by BILAG) were also significantly more common in these patients (P = 0.005). None of the other parameters, including creatine kinase, were significantly different between the two patient subgroups. Thus, LV in needle quadriceps muscle biopsy specimens is a further valuable marker of disease activity in patients with SLE and might provide histological evidence of a systemic vasculitic process in a group of patients with diverse clinical manifestations.

Serological markers of disease activity in systemic lupus erythematosus

When measured serially by Farr assay at a frequency of approximately once a month, changes in levels of anti-dsDNA appear to be a good predictor of clinical disease activity. Although the role of antibodies to the RNA component of snRNP awaits further studies, measurement of anti-UsnRNP antibody levels seems to be of limited value in monitoring lupus patients in clinical practice. The same holds for antibodies to SSA (Ro) and anti-histone antibodies. More recently described antibodies to C1q are probably useful in the follow-up of SLE patients suspected of proliferative renal involvement. The best alternative to measuring levels of the antibodies mentioned before is probably serial analysis of activation of the complement cascade. Levels of complement factors like C3, C4 and, functionally, CH50 remain a useful parameter for monitoring disease activity in SLE, although fluctuations in anti-dsDNA as measured by Farr assay seem superior with respect to sensitivity and specificity for an ensuing relapse. Despite the problems in sampling, measuring levels of activated split products of complement factors like C3a, C3d or C5a may prove to be a valuable tool in the follow-up of lupus patients. The involvement of the endothelial surface is illustrated by rising sVCAM-1 levels prior to relapses in SLE. Although one could expect that subsequent inflammation should be reflected by increased levels of inflammatory molecules like CRP and IL-6, the use of these molecules as predictors of lupus activity seems limited. Interferon-alpha as a direct reflector of the effector phase seems, however, rather promising in this respect and awaits longitudinal studies to analyse the possible relation with clinical disease activity and other serological parameters.

Urine neopterin: a new parameter for serial monitoring of disease activity in patients with systemic lupus erythematosus

OBJECTIVE

To investigate the role of serial measurement of urine neopterin concentration in monitoring the progression of systemic lupus erythematosus (SLE) disease activity scored using the British Isles Lupus Assessment Group (BILAG) index.

METHODS

We followed prospectively 68 unselected SLE patients for a total of 464 patient months during which 233 separate assessments were carried out. At each assessment, urine neopterin, determined by high performance liquid chromatography, together with erythrocyte sedimentation rate (ESR) and plasma C3, C4, and C3d were measured and the SLE disease activity scored by a single observer. Serial data sets were analysed using time series modelling techniques.

RESULTS

Single time point analysis showed a significant increase in urine neopterin concentrations in 14 patients who suffered flares of their disease during the study period (p = 0.02). Thirty patients with active disease went into disease remission with significant decreases in their urine neopterin values (p = 0.02). In the time series analysis, a statistically significant association was found between serial concentrations of urine neopterin and BILAG score (r = 0.6, p < 0.05); no other study parameter (ESR and serum C3, C4, and C3d) mirrored SLE disease activity as effectively.

CONCLUSIONS

This study provides initial evidence that changes in urine concentrations of neopterin are significantly correlated with fluctuations in disease activity over time, scored using the BILAG index, amongst individual patients with SLE. Consequently, serial urine neopterin measurements appear to be clinically useful for monitoring disease activity and may contribute substantially to therapeutic decision making in these patients.