Discordance of SSA/Ro and SSB/La cellular antigens in synchronized cells

Emerging roles of SnoRNAs in the pathogenesis and treatment of autoimmune disorders

SnoRNAs (small non-coding RNAs) have recently gained prominence in autoimmune diseases, revealing their crucial role in modulating the immune response and contributing to disease pathogenesis. Initially known for their involvement in ribosomal RNA processing and modification, molecular biology and genomics advancements have uncovered their broader impact on cellular function, especially in autoimmune disorders. Autoimmune diseases represent conditions characterized by the immune system's erroneous attacks on self-tissues, encompassing disorders like systemic lupus erythematosus, rheumatoid arthritis, and multiple sclerosis. The complex etiology of these conditions involves a delicate interplay of genetic and environmental factors. Emerging evidence suggests that snoRNAs initially recognized for their housekeeping roles, extend their influence on immune regulation through diverse mechanisms. SnoRNAs have been implicated in epigenetic modification, directly affecting the gene expression profiles of immune cells. Their ability to guide site-specific changes on ribosomal RNAs and other non-coding RNAs can significantly influence the translation of proteins involved in immune response pathways. Moreover, snoRNAs interact with key immune-related proteins, modulating their functions and subsequently impacting immune cell development, activation, and tolerance. Dysregulation of snoRNA expression has been observed in various autoimmune diseases, underscoring their potential as biomarkers for disease diagnosis, prognosis, and therapeutic targets. Manipulating snoRNA expression or activity is a promising therapeutic intervention avenue, offering the potential for personalized treatment strategies in autoimmune diseases. However, there remains a need for comprehensive research efforts to elucidate the precise molecular mechanisms underlying snoRNA-mediated immune modulation. Further investigations in this domain are essential to unravel the potential of snoRNAs in autoimmune disorders.

Evaluation of the automatic fluorescent image analyzer, Image Titer, for quantitative analysis of antinuclear antibodies

By making comparisons with the usual manual method, we evaluated an automatic fluorescent image analyzer (Image Titer, Tripath Imaging, Burlington NC), the software for which was developed to simplify measuring indirect immunofluorescent antinuclear antibodies (FANAs). In this new system, images of the stained sample are displayed, and it measures the FANA titer and staining pattern using only 1 slide per subject and does not required the staining of a series of diluted samples as does the manual method. This system showed good reproducibility and linearity for 4 types of control serum samples (with homogeneous, speckled, discrete speckled, and nucleolar staining patterns). In 132 serum samples, consistency between the methods was 100% for the FANA staining pattern and 93.9% for the FANA titer. The Image Titer system detected each pattern in samples with 2 mixed patterns. This system should partly reduce labor and lead to results with minimum differences among individuals, including newly trained persons.

Antinuclear antibodies in dermatology

Antinuclear antibodies are used in the diagnosis and evaluation of patients with connective tissue diseases. The study of antinuclear antibodies has also fundamentally expanded our understanding of nuclear anatomy and function. This article reviews the clinically relevant antinuclear antibodies and their disease associations. Developing an understanding of the utilities and limitations of antinuclear antibodies is essential to providing the expert diagnoses prognoses, and care expected of a dermatologist.

Disparate locations of the 52- and 60-kDa Ro/SS-A antigens in cultured human keratinocytes

Anti-52- and anti-60-kDa Ro/SS-A (Ro) autoantibodies are produced by most patients with subacute cutaneous lupus erythematosus and neonatal lupus erythematosus and are thought to be pathogenic in these two disorders. To learn more about the epidermal antigens targeted by Ro autoantibodies, a panel of anti-52 and anti-60-kDa Ro antibodies was purified from human autoimmune sera and rabbit antisera and then used to: (i) determine the expression and location of the Ro antigens in human keratinocytes; (ii) clarify discrepancies in previous localization studies; and (iii) verify the existence of Ro autoantibodies that cross-react with the 52- and 60-kDa Ro antigens, as previously reported. By immunoblot analysis these antibodies demonstrate that 52- and 60-kDa Ro proteins are expressed in normal human skin and cultured keratinocytes. By indirect immunofluorescence studies with cultured human cells, the anti-52-kDa Ro antibodies produce fine granular cytoplasmic fluorescence and less intense nuclear fluorescence, with apparent nucleolar sparing. The anti-60-kDa Ro autoantibodies produce weak cytoplasmic fluorescence and intense coarse granular nuclear fluorescence with apparent nucleolar sparing. We found distinct differences in the intracellular localization of the 52- and 60-kDa Ro autoantigens. This difference suggests that the 52-and 60-kDa Ro antigens may have independent cellular functions. Finding 60-kDa Ro antigen predominantly in the nucleus challenges the notion that the majority of the intracellular 60-kDa Ro antigen is complexed with the cytoplasmic hY RNA. Additionally, our failure to find a cross-reactive epitope on these two proteins indicates that the 52-kDa Ro antigen is probably a true immunogen and not merely a protein that cross-reacts with anti-60-kDa Ro autoantibodies, as others have suggested.

Molecular characterization of the Ro/SS-A autoantigens

Molecular techniques have recently revealed that there are several immunologically distinct Ro/SS-A antigens. Three genes encoding putative Ro/SS-A protein antigens with calculated masses of 46, 52, and 60 kD have been isolated. The encoded amino acid sequence of each is quite dissimilar. The 46-kD antigen is calreticulin (CR), a highly conserved calcium-binding protein that resides predominately in the endoplasmic reticulum where it may be involved in protein assembly. Although CR has recently been confirmed to be a new human rheumatic disease-associated autoantigen, its relationship to the other components of the Ro/SS-A ribonucleoprotein has become somewhat controversial owing predominately to the fact that recombinant forms of calreticulin have not displayed the same pattern of autoantibody reactivity possessed by the native form of this protein. The 52-kD antigen most likely resides in the nucleus and may be involved in the regulation of gene expression. The cellular location and function of the 60-kD antigen is uncertain but studies indicate that it is a RNA-binding protein. The 46- and 60-kD antigens share homology with foreign polypeptides, suggesting that an immune response initially directed against a foreign protein may give rise to the autoimmune response directed at cross-reacting self proteins.

Comparison of IgG subclass autoantibodies in patients with systemic lupus erythematosus and subacute cutaneous lupus erythematosus

Circulating antinuclear antibodies and in vivo bound immunoglobulins at the dermal-epidermal junction are frequently seen in patients with lupus erythematosus. The present study was designed to examine the distribution of the IgG subclasses of in vivo skin bound IgG and circulating antinuclear antibodies (ANA) in patients with systemic lupus erythematosus (SLE) or subacute cutaneous lupus erythematosus (SCLE). Immunofluorescence studies on skin biopsies showed IgG1 to be the predominant IgG subclass in SCLE patients, present in 20 of 21 (95%) of the specimens. IgG2 was present in 4 patients (19%), IgG3 in 1 (5%), and IgG4 in 7 (33%). The frequencies of IgG2, IgG3, and IgG4 skin staining were significantly higher in the seven SLE patients who were studied: IgG1 in 7/7 (100%), IgG2 in 7/7 (100%) and IgG4 in 6/7 (86%). Immunoblot analysis for the IgG subclasses was performed on serum of 29 patients with SCLE who had antibodies to SSA/Ro antigen. Twenty-seven (93%) of these patients were positive for IgG1 anti-SSA/Ro antibody, while the frequencies for IgG2, IgG3, and IgG4 anti-SSA/Ro were very low. These studies indicate that there is a difference in the IgG subclass antibody response in patients with SLE and SCLE. The presence of more than one subclass antibody may be indicative of systemic disease.

Ro/SS-A and the pathogenic significance of its antibodies

Ro/SS-A is a soluble cellular protein to which antibodies are frequently directed in patients with Sjögren's syndrome (SS) and systemic lupus erythematosus (SLE)-related disorders. The pathogenic significance of these antibodies is uncertain. Our effort to further characterize the immunological and structural nature of Ro/SS-A suggests that the native human Ro/SS-A molecule is not glycosylated and consists of two disulfide linked domains. The amino terminus of the smaller domain contains a major epitope reactive with anti-Ro/SS-A sera. We have isolated and characterized a complementary DNA (cDNA) clone which encodes the Ro/SS-A polypeptide. The Ro/SS-A gene does not appear to be highly polymorphic and exists as a single copy on the short arm of chromosome 19. The isolation of the Ro/SS-A cDNA should allow for a more complete characterization of Ro/SS-A epitopes which should help further elucidate the importance of Ro/SS-A antibodies in the pathogenesis of disease.

Localization of Ro (SS-A) antigen in the cardiac conduction system

The presence of anti-Ro (SS-A) antibody in maternal serum has been associated with congenital heart block. Using human sera monospecific for anti-Ro (SS-A) antibodies in an indirect immunofluorescence assay, Ro (SS-A) antigen was found to be present in the nuclei of myocardial cells and cells of the cardiac conduction system. The possible relationship between the location of Ro (SS-A) antigen, anti-Ro (SS-A) antibody, and heart block is discussed.