Circulating antibodies to guanosine in systemic lupus erythematosus: correlation with nephritis and polyserositis by acute and longitudinal analyses

GC/MS and LC/MS serum metabolomic analysis of Chinese LN patients

China, being a densely populated nation, faces a substantial economic burden due to a high incidence of lupus nephritis (LN) cases. The concealed onset of LN has resulted in many individuals have missed the optimal timing for treatment. The aim of the research is to study the serum metabolomics of Chinese LN patients using gas chromatography (GC)/mass spectrometry (MS) and liquid chromatography (LC)/MS to identify potential diagnostic markers. Fifty LN patients and fifty normal controls, matched for Body Mass Index (BMI) and age, were selected. Serum analysis was conducted using GC/MS and LC/MS, followed by multivariate statistical analysis. Various multidimensional analyses, including principal component analysis, partial least squares discrimination analysis, and orthogonal partial least squares discrimination analysis, along with one-dimensional analyses such as t-tests, were performed. Metabolites with variable importance in projection value > 1 and a p-value < 0.05 were considered critical biomarkers for LN. Furthermore, identified biomarkers delineated relevant metabolic pathways, and a metabolic pathway map was obtained from the database. Forty-one metabolites were identified as potential LN biomarkers, primarily associated with immune regulation, energy metabolism, intestinal microbial metabolism, renal damage, and oxidative stress. The potential for diagnosing LN and other diseases through metabolomics is demonstrated. Future research should explore larger sample sizes, metabolomic comparisons across different diseases and health states, and integration of metabolomics with clinical diagnostics. Such studies will enhance the understanding of metabolomics in medical diagnosis and provide robust support for its practical application.

Predictive value of autoantibodies for activity of systemic lupus erythematosus

There is no serologic test that reliably measures disease activity in systemic lupus erythematosus (SLE). The ‘gold standard’ is the anti-dsDNA antibody test, which has been used as a marker of disease activity by clinicians in SLE for over 35 years. Anti-dsDNA antibodies perform best in those with lupus nephritis, specifically in the presence of a proliferative lesion [World Health Organization (WHO) class III or IV] on renal biopsy. In one recent meta-analysis, the mean positivelikelihood ratio of anti-dsDNA antibodies as a marker of disease activity in SLE was 4.14, implying the overall predictive effect was small. More recently autoantibodyassays have been developed that show greater promise in gauging SLE disease activity, specifically anti-nucleosome and anti-C1q antibodies (especially with renal disease activity). Other tests thought previously to be lacking in specificity that refinements in ELISA technology now render possibly useful include anti-heparan sulfate, anti-ssDNA and anti-Scl-70 autoantibodies. Other tests that as yet have not been shown to be as reliable (and therefore are not as useful in clinical practice for serial determinationto measure disease activity) include other anti-extractablenuclear antibodies (anti-Ro, La, Sm, RNP), anti-cardiolipinantibodies, and anti-nuclear cytoplasmic antibodies (ANCA). New technologies using proteomic determinations show promise as aids in the search for more reliable and feasible autoantibody determinations of disease activity in SLE.

Autoantibodies from schizophrenia patients induce cerebral cox-1/iNOS mRNA expression with NO/PGE2/MMP-3 production

We demonstrated that circulating antibodies from schizophrenia patients, which interact with cerebral M1 muscarinic acetylcholine receptors (M1 mAChRs), trigger production of nitric oxide (NO), prostaglandin E2 (PGE2) and matrix metalloproteinase-3 (MMP-3), and act as inducers of cyclooxygenase-1 (cox-1) and inducible nitric oxide synthase (iNOS) mRNA expression in the rat frontal cortex. The corresponding affinity-purified anti-M1 peptide IgG from schizophrenia patients, while stimulating cerebral M1 mAChRs, increases NOS activity, PGE2 and MMP-3 production associated with iNOS over-activity and mRNA expression. Moreover, PGE2 and MMP-3 production is the result of cox-1 expression and activity. All these effects were inhibited by pirenzepine or haloperidol and mimicked the action of the authentic mAChR agonist. Concurrent analysis of the effects of iNOS, phospholipase C, protein kinase C and calcium/calmodulin inhibition showed that antibody up-regulation of NOS activity, PGE2 and MMP-3 production is under the control of the endogenous NO signalling system. These results provide evidence of the role that cholinergic receptor antibodies play in the development of cerebral inflammation, which shows that an antibody that interacts with cerebral mAChRs can induce expression of pro-inflammatory mediators, and support the participation of an autoimmune process in a particular group of chronic schizophrenia patients.

Serum antiguanosine antibodies as a marker for SLE disease activity and pathogen potential

BACKGROUND

This article reviews research conducted on the immunogenicity of the nucleosides of DNA, especially guanosine, the most immunologically active nucleoside. Discussed is the relationship between circulating antibodies to guanosine, their potential role in SLE disease activity, the binding properties of monoclonal antiguanosine antibody (4H2) compared to polyclonal antiguanosine antibodies in humans with SLE, cell membrane penetration by these antibodies and their interference with signal transduction possibly related to their binding to mitochondria and their apparent GTPase activity.

METHODS

Enzyme-linked immunosorbent assay methodology was used to show clinical relationships between antiguanosine antibody levels and disease activity in SLE. These results are discussed along with methods of detecting cell penetration by this antibody using special staining techniques, laser-scanning microscope detection of mitochondrial localization, and interference of cAMP and pKA production/activation. Additionally, there is some discussion regarding the assay used to detect enzymatic activity of antiguanosine antibodies.

RESULTS

Enhanced circulating levels of antiguanosine antibodies in patients with SLE correlate closely with SLE disease activity. Other factors are discussed that support the pathogenic potential of these antibodies, including their ability to penetrate lymphocytes, bind to mitochondria, inactivate mitochondrial function, interfere with signal transduction, and their potential enzymatically activity.

CONCLUSIONS

Antiguanosine antibodies correlate with SLE disease activity and may be pathogenically important in SLE by interfering with signal transduction, inactivating mitochondrial and cell function in patients with SLE.

Regulation of m1 muscarinic receptors and nNOS mRNA levels by autoantibodies from schizophrenic patients

In this paper we demonstrate that, circulating antibodies from schizophrenic patients interacting with cerebral M1 muscarinic acetylcholine receptors (M1 mAChRs), can act as an inducer of m1 mAChR-mRNA, and neuronal nitric oxide synthase (nNOS) mRNA gene expression of rat frontal cortex. The different signaling pathways involved in the autoantibody's actions, were characterized. As previously reported serum autoantibodies from schizophrenic patients reacted against neural cells surface inhibiting the binding of the specific mAChR radioligand to rat cerebral frontal cortex membrane. Moreover, by ELISA using M1 synthetic peptide (with identical aminoacid sequence to human M1 mAChR) as coating antigen we demonstrated the reactivity against the second extracellular loop of human cerebral M1 mAChR. The corresponding affinity-purified anti M1 peptide IgG (anti M1 peptide IgG) from schizophrenic patients by stimulation of M1 mAChR exerted an increase in m1 mAChR-mRNA and nNOS-mRNA levels, that significantly correlated with the accumulation of phosphoinositides (IPs) and activation of NOS (alpha = 0.05). All these effects were blunted by pirenzepine and mimicked the action of the authentic agonist. Concurrent analysis of the effects of nNOS, phospholipase C (PLC) and calcium/calmodulin (CaM) inhibition on both, m1 mAChR-mRNA and nNOS-mRNA levels, showing that antibody up-regulation mRNA level is under the control of endogenous nitric oxide (NO) signaling system. On the basis of our results, the activation of M1 mAChR by schizophrenic autoantibody appears to induce nNOS-mRNA expression and reciprocally, the activation of NOS up-regulates m1 mAChR gene expression. These results gave support to the participation of an autoimmune process in a particular group of chronic schizophrenic patients.

Clinical and prognostic value of autoantibodies in puerto Ricans with systemic lupus erythematosus

The aim of this study was to determine the association between lupus autoantibodies and the clinical manifestations and outcome in a cohort of Puerto Ricans patients with systemic lupus erythematosus (SLE). All patients fulfilled the American College of Rheumatology classification criteria for SLE. Demographic parameters, clinical manifestations over time and damage accrual were obtained at the last study visit. Disease damage was assessed with the Systemic Lupus International Collaborating Clinics Damage Index (SDI). ANA, ANA pattern, and anti-dsDNA, anti-Smith, anti-Ro (SSA), anti-La (SSB) and anti-snRNP antibodies were measured at the time of SLE diagnosis. Chi-square test, Fisher exact test, ANOVA, logistic regression and general lineal model analyses were used to evaluate these associations. Ninety-six percent of patients were females. The cohort had a mean age of 40.2 +/- 12.0 years and mean disease duration of 9.6 +/- 7.0 years. Patients with elevated anti-dsDNA antibodies were more likely to have vasculitis, pericardial effusion, renal involvement, anaemia, leukopenia, lymphopenia and thrombocytopenia. Anti-Smith antibodies were positively associated with skin ulcerations, elevated liver enzymes, renal involvement and thrombocytopenia. Anti-Ro antibodies were related with the presence of discoid lupus, serositis, pneumonitis, elevated liver enzymes, hemolytic anaemia, leukopenia and lymphopenia. No positive associations were found for anti-snRNP or anti-La antibodies. The presence of anti-dsDNA, anti-Smith and anti-Ro antibodies was associated with higher SDI scores. In conclusion, anti-dsDNA, anti-Smith and anti-Ro antibodies are associated with several clinical manifestations and more damage accrual in Puerto Ricans with SLE. These findings provide valuable clinical and prognostic information for this ethnic population.

Autoantibodies against cerebral muscarinic cholinoceptors in Sjögren syndrome: functional and pathological implications

Previous studies have demonstrated that antibodies against muscarinic acetylcholine receptors (mAChRs) from exocrine glands, correlates with Sjögren syndrome (SS) in the majority of patients. The aim of the present investigation was to establish if serum IgG antibodies present in SS interacts with cerebral mAChRs. Results show that anti-cerebral IgG are present in the sera of 40% SS patients studied. Autoantibodies were able to interact with mAChRs of cerebral frontal cortex membranes inhibiting the [(3)H]QNB binding to its specific receptor. Moreover, tested by ELISA and dot blot they recognized the synthetic peptides corresponding to the second extracellular loop of human M(1) and M(3) mAChR. In addition, the corresponding affinity-purified anti-M(1) and anti-M(3) peptide IgGs displayed an agonistic activity, stimulating phosphoinositide hydrolysis. The results support the notion that serum IgG autoantibodies in SS patients target cerebral mAChRs may have some role in the pathogenesis of higher cognitive dysfunction present in SS patients.

Antibodies to guanosine triphosphate misidentified as anti-double-stranded DNA antibodies in a patient with antinuclear antibody-negative lupus, due to buckling of insolubilized assay DNA

OBJECTIVE

To investigate why the serum of a pediatric patient with systemic lupus erythematosus was persistently (>30 months) and strongly positive for antibodies to double-stranded DNA (dsDNA) as revealed by enzyme-linked immunosorbent assay (ELISA), but yielded negative results on the antinuclear antibody test (HEp-2 immunofluorescence [IF]).

METHODS

The patient's antibodies were isolated on dsDNA and single-stranded DNA (ssDNA) supports, which were then examined by dsDNA ELISA and HEp-2 IF. Tests included the use of various inhibitors to determine the fine specificity of the antibodies. Other tests performed included immunoblotting, immunoprecipitation, Crithidia luciliae IF, and neutrophil IF.

RESULTS

The antibodies isolated from the dsDNA and ssDNA supports were similar, in that they were of the IgG type, bound well in the dsDNA ELISA, and recognized a normally hidden nucleolar RNA antigen in HEp-2 cells. With both the dsDNA ELISA and nucleolar antigens, inhibition studies revealed that the epitope recognized was guanosine 5'-triphosphate (GTP). Binding of the antibodies was better to GTP than to guanosine 5'-monophosphate or cytidylyl (3'-5') guanosine, and, in turn, was better than to guanosine, while N7-methylated GTP was unreactive. The antibodies did not bind to dsDNA present in solution or in HEp-2 or Crithidia cells, but bound transfer RNA well and recognized a cytoplasmic RNA antigen in neutrophils.

CONCLUSION

A new problem in dsDNA ELISA is revealed in the occurrence of a hitherto-unknown and unusual buckling of the insolubilized DNA molecule, which, absent in dsDNA found in solution or in whole cells, presumably creates gaps of single-strandedness in the molecule. A new antibody specific for GTP is described in this patient, which may be clinically important.

Antibodies against astrocyte M1and M2muscarinic cholinoceptor from schizophrenic patients' sera

We demonstrated the presence of circulating antibodies from schizophrenic patients able to interact with cultured astrocytes activating muscarinic acetylcholine receptors (mAChRs). Sera and purified IgG from 15 paranoid schizophrenic and 15 age-matched normal subjects were studied by indirect immunofluorescence (IFI), flow cytometry, dot blot, enzyme immunoassay (ELISA), and radioligand competition assays. Astrocyte membranes and/or a synthetic peptide, with identical amino acid sequence of human M(1) and M(2) mAChR, were used as antigens. By IFI and flow cytometry procedures, we proved that serum purified IgG fraction from schizophrenic patients, reacted to astrocyte cell surface. The same antibodies were able to inhibit the binding of the specific mAChR radioligand (3)H-QNB. Using synthetic peptide for dot blot and ELISA, we demonstrated that these antibodies reacted against the second extracellular loop of human cerebral M(1) and M(2) mAChR. Also, the corresponding affinity-purified antipeptide antibody displayed an agonistic-like activity associated to specific M(1) and M(2) mAChR activation, increasing inositol phosphates accumulation and decreasing cyclic AMP production, respectively. This article gives support to the participation of an autoimmune process in schizophrenia disease.

Antibodies against cerebral M1 cholinergic muscarinic receptor from schizophrenic patients: molecular interaction

We demonstrated the presence of circulating Abs from schizophrenic patients able to interact with cerebral frontal cortex-activating muscarinic acetylcholine receptors (mAChR). Sera and purified IgG from 21 paranoid schizophrenic and 25 age-matched normal subjects were studied by indirect immunofluorescence, flow cytometry, immunoblotting, dot blot, ELISA, and radioligand competition assays. Rat cerebral frontal cortex membranes and/or a synthetic peptide, with an amino acid sequence identical with that of human M(1) mAChR, were used as Ags. By indirect immunofluorescence and flow cytometry procedures, we proved that serum-purified IgG fraction from schizophrenic patients reacted to neural cell surfaces from rat cerebral frontal cortex. The same Abs were able to inhibit the binding of the specific M(1) mAChR radioligand [(3)H]pirenzepine. Immunoblotting experiments showed that IgG from schizophrenic patients revealed a band with a molecular mass coincident to that labeled by an anti-M(1) mAChR Ab. Using synthetic peptide for dot blot and ELISA, we demonstrated that these Abs reacted against the second extracellular loop of human cerebral M(1) mAChR. Also, the corresponding affinity-purified antipeptide Ab displayed an agonistic-like activity associated to specific receptor activation, increasing cyclic GMP production and inositol phosphate accumulation, and protein kinase C translocation. This paper gave support to the participation of an autoimmune process in schizophrenia.