Anti-telomere antibodies in systemic lupus erythematosus (SLE): a comparison with five antinuclear antibody assays in 430 patients with SLE and other rheumatic diseases

Small RNA and Toll-like receptor interactions: origins and disease mechanisms

Advances in small RNA sequencing have revealed diverse small noncoding RNAs (sncRNAs) beyond microRNAs (miRNAs), derived from transfer RNAs (tRNAs), ribosomal RNAs (rRNAs), small nuclear RNAs (snRNAs), and Y RNAs, carrying distinct RNA modifications. These emerging sncRNAs can function beyond RNA interference (RNAi), adopting aptamer-like roles by interacting with Toll-like receptors 7 and 8 (TLR7 and TLR8) via specific sequences, modifications, and structures. We propose a Sequential Activation Hypothesis where initial abnormal sncRNAs - triggered by infections or stresses - activate TLR7/8, leading to autoantibody production against autoantigens like RNA-binding proteins La and Ro. These autoantibody-antigen complexes further promote secondary immunogenic sncRNA production and repetitive TLR7/8 activation, perpetuating a vicious cycle sustaining autoimmunity. TLR7/8's X chromosome location and sex-biased expression contribute to female-dominant autoimmune diseases. Understanding sncRNA-TLR interactions is essential for designing novel therapeutic strategies.

The NZB/W F1 mouse model for Sjögren's syndrome: A historical perspective and lessons learned

Sjögren's syndrome (SS) is a chronic rheumatic autoimmune disorder affecting multiple organ systems. The clinical findings in SS patients show considerable heterogeneity and overlap with other autoimmune diseases. In addition, the autoimmune response in SS initiates several years before the appearance of clinical symptoms. Thus, understanding the pathogenic mechanisms involved in the disease process have been a challenge. Several animal model systems of SS-like disease have been developed to overcome these issues. The New Zealand Black (NZB) x New Zealand White (NZW) F1 (NZB/W F1) mouse represents the first spontaneous mouse model of SS. In this review, we provide a historical perspective and detailed description of this mouse model focusing on exocrine gland histopathology, autoantibody populations, and glandular dysfunction. Considering that NZB/W F1 mice also develop a systemic lupus erythematosus (SLE)-like disease, this mouse model mimics the clinical presentation of polyautoimmunity seen in a sizable subset of SS patients. It is plausible that such patients will require distinct therapeutic interventions necessary to treat both SLE and SS. Therefore, the NZB/W F1 mouse is a powerful tool to decipher pathogenic mechanisms involved in SS related polyautoimmunity and develop appropriate therapeutic strategies.

Telomere dysfunction-related serological markers and oxidative stress markers in rheumatoid arthritis patients: correlation with diseases activity

Rheumatoid arthritis (RA) is an inflammatory autoimmune polyarthritis with progressive destruction of the synovial joints associated with systemic manifestations. RA is characterized by infiltration of the synovial joints with inflammatory immune cells with premature immunosenescence. Shorter telomere length in the peripheral blood cells and increase in the oxidative stress have been detected in patients with RA. The aim of the present study was to study the association of markers of telomere shortening and oxidative stress with RA disease activity. Sixty-one RA patients and 15 healthy controls were enrolled in the study. Demographic data, clinical examination, and disease activity status were evaluated for the RA patients. Serum levels of chitinase and NAG (telomere markers) were determined by biochemical reactions using colloidal chitin and NAG as substrates, respectively. Nitric oxide and superoxide dismutase (oxidative stress markers) were determined colometrically and spectrophotometrically, respectively, in the sera of RA patients and controls. Results were correlated with disease activity. Indices of telomere shortening and oxidative markers were significantly higher in RA patients compared to controls. These indices were correlated with signs of disease activity (including number of swollen and tender joints, DAS-28, and inflammatory markers). Rheumatoid arthritis is a disease in which markers of telomere shortening and elevated oxidant stress correlate with disease activity.

SLE-key(®) rule-out serologic test for excluding the diagnosis of systemic lupus erythematosus: Developing the ImmunArray iCHIP(®)

We describe here the development, verification and validation of the SLE-key(®) rule-out test for a definitive rule-out of a diagnosis of systemic lupus erythematosus (SLE). The test uses the proprietary iCHIP(®) micro-array technology platform (Fattal et al., 2010) to identify discriminating patterns of circulating autoantibodies among SLE patients compared with self-declared healthy individuals. Given the challenges associated with the diagnosis of SLE and the healthcare costs of delayed diagnosis and misdiagnosis, a definitive rule-out test can provide significant clinical benefits to patients and potentially major cost savings to healthcare systems.

Systemic lupus erythematosus and vitamin D deficiency are associated with shorter telomere length among African Americans: a case-control study

Systemic lupus erythematosus (SLE) is a chronic systemic autoimmune disease that disproportionately affects African American females. The causes of SLE are unknown but postulated to be a combination of genetic predisposition and environmental triggers. Vitamin D deficiency is one of the possible environmental triggers. In this study we evaluated relationships between vitamin D status, cellular aging (telomere length) and anti-telomere antibodies among African American Gullah women with SLE. The study population included African American female SLE patients and unaffected controls from the Sea Island region of South Carolina. Serum 25-hydroxyvitamin D levels were measured using a nonchromatographic radioimmunoassay. Telomere length was measured in genomic DNA of peripheral blood mononuclear cells (PBMCs) by monochrome multiplex quantitative PCR. Anti-telomere antibody levels were measured by enzyme-linked immunosorbent assay (ELISA). Patients with SLE had significantly shorter telomeres and higher anti-telomere antibody titers compared to age- and gender-matched unaffected controls. There was a positive correlation between anti-telomere antibody levels and disease activity among patients and a significant correlation of shorter telomeres with lower 25-hydroxyvitamin D levels in both patients and controls. In follow-up examination of a subset of the patients, the patients who remained vitamin D deficient tended to have shorter telomeres than those patients whose 25-hydroxyvitamin D levels were repleted. Increasing 25-hydroxyvitamin D levels in African American patients with SLE may be beneficial in maintaining telomere length and preventing cellular aging. Moreover, anti-telomere antibody levels may be a promising biomarker of SLE status and disease activity.

Anti‐nucleosome antibodies in the diagnosis of systemic lupus erythematosus

OBJECTIVE

To study the prevalence and diagnostic significance of antibodies against nucleosomes in patients with systemic lupus erythematosus (SLE) as compared to five anti-nuclear antibody (ANA) assays.

METHODS

The study included 305 patients with SLE, 125 patients with other autoimmune rheumatic diseases, and 415 healthy controls. Anti-nucleosome antibodies were measured by an enzyme-linked immunosorbent assay (ELISA) and ANA by immunofluorescence (IF) using Hep-2 cells. Anti-double-stranded DNA (anti-dsDNA) antibodies were measured by three commercial ELISAs and by IF using Crithidia luciliae as antigen.

RESULTS

Compared to three ELISAs for anti-dsDNA, the anti-nucleosome assay was less sensitive (30% vs. 29-69%) but equally specific (90% vs. 77-95%) for SLE. The most sensitive test was ANA (76%), and the least sensitive was Crithidia (13%). The correlations between the different assays were good (p < 0.001 for all comparisons).

CONCLUSION

The anti-nucleosome antibody assay does not offer additional information compared to conventionally used anti-dsDNA tests in the differential diagnosis of SLE.

Clinical and laboratory characteristics of Finnish lupus erythematosus patients with cutaneous manifestations

Our objective was to characterize clinical features, laboratory findings, concomitant autoimmune diseases, and smoking habits of lupus erythematosus subgroups in genetically homogeneous patients from two Dermatology Departments of Finnish University hospitals. One hundred and seventy eight discoid lupus erythematosus, 55 subacute cutaneous lupus erythematosus, and 77 systemic lupus erythematosus patients were enrolled using patients' charts from institutional database (1995-2006) and during routine control visits. Clustering analysis was performed to reveal natural groupings. Smoking at the onset of disease was significantly more common in all subgroups (57% for discoid lupus erythematosus, 35% for subacute cutaneous lupus erythematosus, and 34% for systemic lupus erythematosus) compared with the age/gender-matched prevalence in the Finnish population, suggesting smoking to be a trigger factor for cutaneous lupus. Leukopenia (38%) and lymphopenia (52%) were observed more often in patients with systemic lupus erythematosus than reported previously. Photosensitivity characterized all groups, especially patients with subacute cutaneous lupus erythematosus (87%). Of the autoimmune diseases, Sjögren's syndrome was the most common (22% of patients with systemic lupus erythematosus), followed by autoimmune thyroid disease (13% of patients with subacute cutaneous lupus erythematosus). The clustering analysis showed environmental factors (smoking) to be more involved in disease development in discoid lupus erythematosus, whereas immunological factors were more significant in initiating systemic lupus erythematosus. The high prevalence of autoimmune thyroid disease, together with photosensitivity, and the clustering profiles suggest that lupus erythematosus subtypes, especially discoid lupus erythematosus, are heterogeneic in their pathomechanisms.

Premature telomere shortening in polymorphonuclear neutrophils from patients with systemic lupus erythematosus is related to the lupus disease activity

We investigated whether premature telomeric loss occurred in peripheral polymorphonuclear neutrophils (PMN) as well as mononuclear cells (MNC) from patients with systemic lupus erythematosus (SLE). We measured the telomere length of MNC and PMN in 60 SLE patients and 26 sex-, race- and age-matched healthy volunteers by Southern blotting with chemiluminescence method. The possible predisposing factors associated with telomere change were also analysed. We found the telomere length of MNC and PMN shortened with age in different degrees in both SLE and control groups. Compared to the control group, the telomere length was shortened in both SLE-MNC (6.08 kb in SLE versus 6.71 kb in control, P = 0.0008) and PMN (6.24 kb in SLE versus 6.75 kb in control, P = 0.0025). The average reduction in telomere length in SLE patients was equivalent to a premature senescence of 16.5 years in MNC and 13.4 years in PMN. In addition, the accelerated telomere shortening was more prominent in SLE patients younger than 45 years old. SLE disease activity (SLEDAI) contributed remarkably to the accelerated telomere erosion, at least in PMN. Moreover, the telomere length of MNC was significantly shorter than PMN in the same SLE patients with leukopenia and lymphopenia. These data suggested that MNC and PMN from patients with SLE displayed premature and accelerated telomere shortening that SLE is an independent factor for it.

Cytokine induction by circulating immune complexes and signs of in-vivo complement activation in systemic lupus erythematosus are associated with the occurrence of anti-Sjögren's syndrome A antibodies

Circulating immune complexes (IC) and levels of IC-induced cytokines have been correlated with complement activation and autoantibody profiles in systemic lupus erythematosus (SLE). SLE sera were analysed concerning levels of immune complexes (IC), classical complement function and different antinuclear and anti-C-reactive protein (CRP) autoantibodies. Blood mononuclear cells from healthy donors were stimulated with isolated IC and production of interleukin (IL)-10, IL-6 and IL-12p40 was measured. Functional experiments revealed that increased levels of IC-induced cytokines were associated with both increased classical complement activation and the occurrence of anti-Sjögren's syndrome A (SSA) and anti-SSB but not other autoantibodies. Biochemical measurement of circulating IC showed that the degree of complement activation and the occurrence of anti-SSA were synergistically associated with levels of circulating IC in SLE sera, as complement activation was a prerequisite for the enhancing effect of anti-SSA. Anti-CRP was associated with complement activation, but not with other autoantibodies. Our results indicate that anti-SSA and possibly anti-SSB antibodies influence IC formation and subsequent IC-induced cytokine induction, and that they thereby participate in the inflammatory process in active SLE.

A new oligonucleotide-based ELISA for the detection of anti-double-stranded DNA antibodies

The detection and measurement of antibodies to double-stranded (ds) DNA is important in the diagnosis and monitoring of patients with systemic lupus erythematosus (SLE). Several methods are available for their determination but none of them is completely satisfactory. Usually, purified dsDNA from different sources is used as antigen in the solid (enzyme-linked immunosorbent assay, ELISA) or liquid phase (Farr assay). Alternatively, anti-dsDNA antibodies can be demonstrated by immunofluorescence, using the haemoflagellate Crithidia luciliae (CLIFT). We have developed a new oligonucleotide-based anti-dsDNA ELISA in which dsDNA, constituted of a 5'photobiotinylated nucleic acid probe and its highly specific complementary oligonucleotide, is formed onto the solid-phase. To do that, a 40 bp probe is coated on the microplate wells via streptavidin-biotin bond and the in vitro (in solid-phase) developed hybrid between probe and its complementary helix used as capturing antigen. The assay has proved to be specific and the several experiments performed to ascertain the absence of single-stranded DNA (ssDNA) contamination and/or non specific binding to plastic, streptavidin, probe (without complementary chain) have all excluded any significant interference. To evaluate the clinical performance of this new assay, 114 serum samples from 68 SLE patients and 85 samples from 85 disease controls, in addition to 30 blood donors, were studied. The results were compared with commercial ELISAs, Farr assay and indirect immunofluorescence. The sensitivity and specificity were 66.2 and 96.4%, respectively, comparable and even better than those of the commercially available anti-dsDNA kits. Anti-dsDNA antibody levels, measured with the oligonucleotide-ELISA, correlated with SLE clinical activity determined using the European Consensus Lupus Activity Measurement (ECLAM) (r = 0.59, p < 0.0001). In conclusion, this assay has proved to be reproducible, and the results correlate well with other standard anti-dsDNA assays. The features of this new assay make it promising for clinical use.