[Clinical significance of antiribosomal antibodies. Study Group on Autoimmunity (GEAI)]

Depressive and Anxiety Disorders in Systemic Lupus Erythematosus Patients without Major Neuropsychiatric Manifestations

Depressive and anxiety disorders are frequently observed in patients with Systemic Lupus Erythematosus (SLE). However, the underlying mechanisms are still unknown. We conducted this survey to understand the prevalence of depression and anxiety in SLE patients without major neuropsychiatric manifestations (non-NPSLE) and to explore the relationship between emotional disorders, symptoms, autoantibodies, disease activity, and treatments in SLE. 176 SLE patients were included, and SLE disease activity index (SLEDAI), Hamilton Depression Rating Scale (HAMD), and Hamilton Anxiety Rating Scale (HAMA) were recorded to evaluate their disease activity and emotional status. We found that depressive and anxiety disorders were common among SLE patients: 121 (68.8%) patients were in depression status while 14 (8.0%) patients could be diagnosed with depression. Accordingly, 101 (57.4%) were in anxiety status and 21 (11.9%) could be diagnosed with anxiety. Depression was associated with disease activity, and anxiety was associated with anti-P0 antibody, while both of them were associated with proteinuria. HAMA and HAMD scores were in strong positive correlation and they were independent risk factors of each other. We concluded that the high prevalence of depression and anxiety and the association between depression and SLE disease activity might reveal the covert damage of central nervous system in SLE. The role of anti-P0 antibody in SLE patients with emotional disorders warrants more researches.

Expression and characterization of Pen b 26 allergen of Penicillium brevicompactum in Escherichia coli

Pen b 26 is one of the allergens produced by Penicillium brevicompactum which is one of the most prevalent in door airborne fungi and a major source of respiratory problems, including asthma. Pen b 26 wa scloned and expressed as an N-terminal as well as a C-terminal His6 tagged fusion protein in Escherichia coli. This allergen was purified by immobilized Ni2+-affinity chromatography. The purified Pen b 26 was characterized by immunological, biochemical and biophysical methods. C-His6 tagged Pen b 26 produced several fold greater yield than N-His6 tagged Pen b 26. The affinity of C-His6 tagged Pen b 26 for the specific antibody was also 2.75 times higher than N-His6 tagged Pen b 26

Accuracy of anti–ribosomal P protein antibody testing for the diagnosis of neuropsychiatric systemic lupus erythematosus: An international meta-analysis

OBJECTIVE

To quantitatively evaluate the diagnostic accuracy of antibodies to ribosomal P proteins (anti-P) for neuropsychiatric systemic lupus erythematosus (NPSLE) in general, for psychosis, mood disorder, or both, and for other diffuse manifestations.

METHODS

This international meta-analysis combined standardized data from 1,537 lupus patients contributed by 14 research teams. Weighted estimation of sensitivity and specificity with fixed-effects and random-effects models, as well as summary receiver operating characteristic (SROC) curve analysis, was used to summarize test performance. The robustness of the overall estimates was examined in sensitivity analyses that included additional studies published up to November 1, 2004 in the Medline, EMBase, and Cochrane databases.

RESULTS

Combining the data from the 14 teams, the weighted sensitivity and specificity estimates for the diagnosis of NPSLE were 26% (95% confidence interval [95% CI] 15-42%) and 80% (95% CI 74-85%), respectively. For psychosis, mood disorder, or both, the sensitivity and specificity were 27% (95% CI 14-47%) and 80% (95% CI 74-85%), respectively. For other diffuse manifestations, the sensitivity was 24% (95% CI 12-42%), and the specificity was 80% (95% CI 73-85%). The proportion of patients with anti-P antibodies did not vary markedly across different presentations of NPSLE. Between-study heterogeneity was substantial, but the SROC curves were consistent with the weighted estimates. In further analyses that included another 24 published studies, only the sensitivity for psychosis and/or mood disorder was slightly improved, but it was still suboptimal (42% [95% CI 30-53%]); the specificity remained essentially the same (81% [95% CI 76-85%]).

CONCLUSION

Anti-P antibody testing has limited diagnostic value for NPSLE, and it is not helpful in differentiating among various disease phenotypes.

Evaluating inflammatory joint disease: how and when can autoantibodies help?

The diagnosis of inflammatory joint disease rests on a constellation of symptoms, signs, laboratory test results and, occasionally, histological findings. Classification criteria have been developed by national learned societies, international panels of experts or, more rarely, an expert working alone. These criteria are intended to provide a common language for therapeutic trials and international publications. Yet, they are often inappropriately used as diagnostic tools for the individual patient. Identification of an early seroimmunologic marker with high sensitivity and specificity for classifying patients with recent-onset joint disease is a daunting challenge. Test performance characteristics such as sensitivity, specificity, positive and negative predictive values, and the positive or negative likelihood ratio help to assess the diagnostic usefulness of a laboratory test in a specific situation. The difference between the pretest and posttest likelihoods of obtaining a positive or negative result measures the usefulness, or performance, of a laboratory test in a specific situation according to the prevalence of the disease. A higher positive likelihood ratio indicates a more useful test. In a patient with inflammatory joint disease, the diagnosis can be sought by assaying a limited number of autoantibodies according to a decision tree. Thus, IgM rheumatoid factors (latex test or ELISA) and antibodies to filaggrin or other citrullinated proteins (antikeratin antibodies by indirect immunofluorescent assay or anticyclic citrullinated peptides by ELISA) identify more than 70% of cases of early rheumatoid arthritis with greater than 98% specificity. If these markers are negative, testing for antinuclear antibodies by indirect immunofluorescent assay on HEp-2 cells identifies 99% of cases of lupus and progressive systemic sclerosis. Confirmation of the diagnosis can be obtained by characterizing the autoantibodies: thus, presence of antidouble-stranded DNA (dsDNA, by the Farr radioimmunoassay, indirect immunofluorescent assay on Crithidia luciliae, or ELISA (IgG)) or of antinucleosome antibodies (ELISA) indicates lupus, whereas anticentromere, antitopoisomerase I (Scl 70), and antinucleolar antibodies point to progressive systemic sclerosis. A positive test for antibodies to soluble nuclear antigens of the U1 RNP type suggests mixed connective tissue disease or lupus but may indicate scleroderma. Anti-Sm antibodies are found in fewer than 10% of lupus patients but are highly specific. Anti-SSA (Ro) and anti-SSB (La) suggest lupus or primary Sjögren's syndrome. When tests are negative for ANA, several antibodies to cytoplasmic organelles are valuable diagnostic tools, such as anti-J01 for polymyositis syndromes and antiribosome antibodies for lupus, although their sensitivity is modest (20-25%). Finally antineutrophil cytoplasmic antibodies (ANCAs) ensure the diagnosis of small-vessel vasculitides, which often involve the lungs and kidneys. Thus, in diffuse Wegener's granulomatosis, ANCAs exhibiting the classic cytoplasmic pattern and corresponding by ELISA to anti-PR3 are found. In microscopic polyangiitis the ANCAs are peripheral and correspond by ELISA to antimyeloperoxidase antibodies. Tests for other antibodies are less often needed to evaluate inflammatory joint disease.

Autoantibody-mediated inhibition of pancreatic cancer cell growth in an athymic (nude) mouse model

INTRODUCTION

Antiribosomal P autoantibodies are detectable in 12-16% of patients with systemic lupus erythematosus.

AIM

To assess whether antiribosomal P autoantibodies could be useful as a novel form of immunotherapy for pancreatic cancer.

METHODOLOGY

Three pancreatic cancer cell lines were incubated with antiribosomal P or normal human immunoglobulin. Viability was assayed with MTT, and apoptosis was detected by TUNEL. MIA PaCa-2 cells were injected into athymic mice. Animals were treated with intraperitoneal antibody or control immunoglobulin. Serum antibody levels were measured by ELISA. Tumor nodule size was measured weekly. Binding of the antibody to tumors was demonstrated with fluorescent microscopy.

RESULTS

Antiribosomal P antibody inhibited pancreatic cancer cell proliferation up to 54.6% (p < 0.01) and was associated with a threefold increase in the rate of apoptosis (p < 0.05). Tumor volume after 4 weeks of treatment was 23.2 mm3, versus 141.5 mm3 for the control group (p < 0.05). Apoptosis rate within the nodules was increased twofold, to 11.4%, in comparison with control (p < 0.05).

CONCLUSION

Antiribosomal P autoantibody at levels similar to those that can exist in SLE inhibits the growth of pancreatic cancer cells, in vitro and in vivo. The mechanism involves surface binding and apoptosis.

Autoantibodies to ribosomal P proteins in systemic lupus erythematosus

Autoantibodies to ribosomal P proteins (anti-P) are directed against three ribosomal phosphoproteins (P0, P1, and P2) and are believed to be specific markers for systemic lupus erythematosus (SLE), particularly with neuropsychiatric manifestations. The objective of this study was to determine the rate of occurrence and clinical significance of anti-P in Tunisian patients.

METHODS

We included 100 Tunisian patients with SLE whose sera were received between January 1998 and December 2000 by the immunology laboratory of the Charles Nicolle Teaching Hospital in Tunis, Tunisia, and were tested for anti-P. An immunodot technique based on a synthetic protein shared by all ribosomal phosphoproteins was used.

RESULTS

Sera from 22 (22%) patients were positive for anti-P. This rate is consistent with the literature. We found no statistically significant associations between anti-P and specific manifestations of SLE. CONCLUSION. We found that anti-P were significantly associated with anti-Sm and anti-RNP, as reported previously. The significance of these associations remains debatable.