Mirna Sentić

Non-MS autoimmune demyelination

Connective tissue diseases can be characterised by central nervous system (CNS) involvement, in some patients manifested by demyelination areas in the white matter of the brain and spinal cord, which are difficult to differentiate from multiple sclerosis (MS) and other demyelinating processes, such as transverse myelitis and optic neuritis. Demyelinating process may be the feature of nervous impairment in systemic lupus erythematosus, Behcets disease (BD), Sjoegrens syndrome (SS), systemic sclerosis (SSc) or very rarely other systemic autoimmune diseases. An acute isolated neurological syndrome, as the most common symptom of MS can sometimes be the only feature or even first manifestation of nervous impairment in connective tissue disease, hence presenting the diagnostic problem. Although the white matter abnormalities seen by magnetic resonance imaging may be similar in non-MS autoimmune demyelination and MS, it is the most important diagnostic tool in the differential diagnosis of the mentioned conditions. Investigating the presence of various autoantibodies potentially involved in the pathogenesis of demyelinating lesions as well as cerebrospinal fluid (CSF) analysis can be helpful.

Decrease in circulating DNA, IL-10 and BAFF levels in newly-diagnosed SLE patients after corticosteroid and chloroquine treatment

Arsenal of pattern-recognition receptors alongside antibody production machinery make B cells vulnerable to autoimmune response if an autoantigen elicits both pathways in a self-sustained fashion. Systemic lupus erythematosus is an autoimmune disease characterized by autoantibodies to DNA, RNA and related structures. Murine studies demonstrated autoreactive B cell activation upon TLR9 stimulation with DNA-containing immune complexes. This activation could be abolished with chloroquine, a drug used in SLE treatment that also blocks TLR9 signaling. We investigated whether chloroquine modulates TLR9 expression, circulating DNA levels and B cell-related cytokines in newly discovered, untreated SLE patients. TLR9 was measured in peripheral blood B cells by flow cytometry, serum DNA by real-time PCR, and IL-10 and BAFF by ELISA before treatment, after 3weeks on corticosteroids, and 3months after introduction of chloroquine. We found that circulating DNA is higher in SLE patients than in controls in every time-point and decreases significantly after chloroquine treatment. Untreated patients had higher serum IL-10 than controls or patients on corticosteroids. Also, corticosteroids decreased and chloroquine completely abolished CpG-mediated CD86 upregulation on B cells and IL-10 secretion in PBMC culture. Providing the TLR9 pathway activation demonstrates its importance in pathogenesis of human SLE, this data supports continuation of chloroquine in SLE treatment protocol. In addition, observed modulation of cytokine and DNA levels after immunomodulatory treatment prompts for inclusion of untreated patients in studies of human immune disorders.

Binding of Anti-Double Stranded (ds) DNA-Positive Sera to Denatured (d) DNA and Synthetic Poly[dA-dT] x Poly[dA-dT] Double Stranded Copolymer in an ELISA Format

Using an ELISA assay anti-nuclear antibody-positive sera from 300 patients with various immune-related diseases and 64 anti-nuclear antibody-negative sera were analysed for binding to S1-nuclease-treated double stranded (ds) DNA. In addition, the pattern of reactivity of 50 selected anti-dsDNA-positive sera was established using denatured (d) DNA and poly[dA-dT] X poly[dA-dT] double-stranded alternating copolymer (dAT) as additional DNA antigens. None of the 64 anti-nuclear antibody-negative sera and 76 of the 300 anti-nuclear antibody-positive sera (25%) were anti-dsDNA-positive. Of the anti-nuclear antibody-positive and anti-dsDNA-positive sera, 48 (63%) were from systemic lupus erythematosus patients, and 7 (9%) from rheumatoid arthritis patients, whereas 21 patients (27.6%) suffered from various immune and non-immune related diseases. Anti-dsDNA-positive reactivity was highly correlated with dDNA and dAT reactivity (r = 0.906, p < 0.0001 and r = 0.93, p < 0.0001, respectively). Although the majority of the 50 selected (37 systemic lupus erythematosus and 13 non-systemic lupus erythematosus) anti-dsDNA-positive sera concomitantly bound to both additional antigens, 7 of these (14%) did not bind to dAT, and 2 (4%) did not bind to dDNA. Anti-dsDNA-positive sera (n = 37) showed a similar pattern, in which 8.1% and 2.7% of sera did not bind to dAT and to dDNA, respectively. In contrast, anti-dsDNA-negative sera from various immune-related diseases bound either ssDNA (12.5%) or dDNA and dAT (12.5%). These data suggest that dsDNA and dAT-based assays detect similar but not identical specificities in the sera of patients suffering from systemic lupus erythematosus and in a proportion of non-systemic lupus erythematosus patients.