Abnormalities in circulating plasmacytoid dendritic cells in patients with systemic lupus erythematosus

Introduction  

Dendritic cells (DCs) are capable of inducing immunity or tolerance. Previous studies have suggested plasmacytoid DCs (pDCs) are pathogenic in systemic lupus erythematosus (SLE). However, the functional characteristics of directly isolated peripheral circulating blood pDCs in SLE have not been evaluated previously.     

Clinical significance of circulating dendritic cells in patients with systemic lupus erythematosus

Dendritic cells are a complex group of mainly bone-marrow-derived leukocytes that play a role in autoimmune diseases. The total number of circulating dendritic cells (tDC), and their plasmacytoid dendritic cell (pDC) and myeloid dendritic cell (mDC1 and mDC2) subpopulations were assessed using flow cytometry. The number of tDC and their subsets were significantly lower in systemic lupus erythematosus patients than in the control group. The count of tDC and their subsets correlated with the number of T cells. The number of tDC and pDC subpopulation were lower in the patients with lymphopenia and leukopenia than in the patients without these symptoms. Our data suggest that fluctuations in blood dendritic cell count in systemic lupus erythematosus patients are much more significant in pDC than in mDC, what may be caused by their migration to the sites of inflammation including skin lesions. Positive correlation between dendritic cell number and TCD4+, TCD8+ and CD19+ B cells, testify of their interactions and influence on SLE pathogenesis. The association between dendritic cell number and clinical features seems to be less clear.     

Circulating proangiogenic molecules PIGF, SDF-1 and sVCAM-1 in patients with systemic lupus erythematosus

Serum concentrations of three angiogenic cytokines: vascular endothelial growth factor (VEGF), stromal cell-derived factor-1 (SDF-1) and placental growth factor (PIGF) and soluble vascular cell adhesion molecule 1 (sVCAM-1), were investigated in the serum of 61 patients with systemic lupus erythematosus (SLE) and 20 healthy subjects. The possible association between serum levels of these proteins and SLE activity, as well as correlation between the concentrations of cytokines were also analysed. All of these factors were detectable in all SLE patients and the healthy control group. The median concentration of VEGF was higher in active SLE (386 pg/mL) than in inactive disease (327 pg/mL) or in the control group (212 pg/mL, p<0.004). The median serum level of SDF-1 was higher in SLE patients (1,814 pg/mL) than in the control group (1,507 pg/mL, p<0.02). The median concentration of PIGF was higher (14 pg/mL) in SLE patients than in the control group (12 pg/mL, p=0.03), and particularly in active disease (17 pg/mL) as compared to the inactive phase (13 pg/mL, p=0.01). The correlations between the levels of cytokines examined and clinical features, laboratory abnormalities and the type of treatment were also analysed. We found a positive correlation between serum concentrations of PIGF and SLE activity according to SLAM score (p=0.33, p=0.13).     

Neuropsychological patterns in systemic lupus erythematosus patients with depression

Thirteen patients with systemic lupus erythematosus and depression (Depressed-SLE), 10 Depressed-Control subjects, and 25 Healthy Control subjects completed cognitive testing and self-report questionnaires of pain, depression, and fatigue. The Depressed-SLE group scored higher on the American College of Rheumatology Neuropsychological Battery for systemic lupus erythematosus cognitive impairment index compared to Depressed-Control and Healthy Control subjects (p < 0.05 and p < 0.02, respectively). No correlations between cognitive impairment and pain, fatigue, or perceived cognitive failures were observed in the Depressed-SLE participants. Moderate agreement (86.4%) was found between a comprehensive neuropsychology battery cognitive impairment index and the ACR-SLE impairment index in the Depressed-SLE patients. Overall, the magnitude and pattern of cognitive impairment in Depressed-SLE patients cannot be explained by depression alone.     

Monocyte activation by apoptotic cells removal in systemic lupus erythematosus patients

Decreased apoptotic cells (ACs) removal has been described as relevant in systemic lupus erythematosus (SLE) pathogenesis. Binding/phagocytosis of ACs was decreased in SLE patients. Blocking experiments suggested a role for CD36 in ACs clearance in healthy controls, not observed in SLE patients. Binding/phagocytosis of ACs induced the production of IL-6, CXCL8 and CCL22 in patients and controls and IL-1β, TNF-α and CCL3 only in healthy controls. ACs clearance induced an increase in CD80 and a decrease in CD86 expression in healthy controls and atherosclerotic patients. However, SLE patients did not up-regulate CD80 expression. The number and expression of CD36 and CD163 in monocytes was not different between the groups. ACs removal induced a down-regulation of CD36 expression in adherent HLA-DR⁺ cells in SLE patients but not healthy controls. The decreased binding/phagocytosis of ACs observed in SLE patients, induces a distinct immune response compared with healthy controls.     

Production of B cell-stimulating factors by B cells in patients with systemic lupus erythematosus

The production of B cell-stimulating factors (BSF) by B cells in patients with systemic lupus erythematosus (SLE) was studied in vitro. B cells from SLE patients markedly proliferated and differentiated into Ig-producing cells by in vitro culture without any stimulation. The culture supernatant of these B cells contained BSF activity that stimulated Staphylococcus aureus Cowan I-treated normal B cells to proliferate and differentiate into Ig-producing cells. By a Percoll gradient density centrifugation, BSF-producing cells were enriched in the higher density fraction, but were reduced in the lower density fraction. The BSF also stimulated the proliferation and the differentiation of SLE B cells. By a Percoll gradient density centrifugation, SLE B cells responsive to the BSF were enriched in the higher density fraction, but were reduced in the lower density fraction. The Mr of the BSF was estimated as about 18,000 Da by Sephacryl S-200 column chromatography. The BSF fraction did not possess IL-2 and IFN activity, but possessed IL-1 activity, which stimulated murine thymocyte proliferative responses. The BSF activity was partially, but not completely, absorbed by an anti-IL-1 alpha antibody. Furthermore, the BSF possessed IL-4 activity, which induced not only the proliferative responses of normal B cells stimulated with B cell mitogens, but also the expression of low affinity Fc epsilon R/CD23 on normal B cells. The BSF also possessed IL-6 activity, which induced the proliferative responses of IL-6-dependent hybridoma cells, MH-60 BSF2. Moreover, human rIL-1, rIL-4, and rIL-6 stimulated SLE B cells. These results suggest that SLE B cells spontaneously produce the BSF such as IL-1 alpha, IL-4, and IL-6 and express their receptors on their surface, and the interaction between the BSF and their receptors stimulates SLE B cells to spontaneously proliferate and differentiate into Ig-producing cells as an autocrine mechanism.     

Increased serum interleukin 17 in patients with systemic lupus erythematosus

Interleukin 17 (IL-17) is a Th17 cytokine associated with inflammation, autoimmunity and defense against some bacteria, it has been implicated in many chronic autoimmune diseases including psoriasis, multiple sclerosis and systemic sclerosis. However, whether IL-17 plays a role in the pathogenesis of systemic lupus erythematosus (SLE) remains unclear. In the present study, we aimed to investigate the serum IL-17 level in patients with SLE and it’s associations with disease manifestations and activity. Fifty-seven patients with SLE and 30 healthy volunteers were recruited. Serum IL-17 levels were examined by enzyme linked immunosorbent assay (ELISA). Statistic analyzes were performed by SPSS 10.01. Results show that serum IL-17 levels were significantly elevated in SLE patients as compared with normal controls. Nevertheless, no associations of serum IL-17 level with clinical and laboratory parameters were found; no significant difference regarding serum IL-17 level between SLE patients with nephritis and those without nephritis was found; no significant difference was found between Less active SLE and More active SLE; Correlation analysis between serum IL-17 levels and SLEDAI showed no association. Taken together, our results indicate increased serum IL-17 levels in SLE patients, suggesting that this cytokine may trigger the inflammatory process in SLE. However, no associations of serum IL-17 level with disease manifestations were found. Therefore, further studies are required to confirm this preliminary data.     

TCR zeta mRNA with an alternatively spliced 3'-untranslated region detected in systemic lupus erythematosus patients leads to the down-regulation of TCR zeta and TCR/CD3 complex

The reduction or absence of TCR zeta-chain (zeta) expression in systemic lupus erythematosus (SLE) patients is thought to be related to the pathogenesis of SLE. Recently, we reported the predominant expression of zeta mRNA containing an alternatively spliced 3'-untranslated region (3'UTR; zetamRNA/as-3'UTR) and a reduction in the expression of zeta mRNA containing the wild-type 3'UTR (zetamRNA/w-3'UTR) in T cells from SLE patients. Here we show that AS3'UTR mutants (MA5.8 cells deficient in zeta protein that have been transfected with zetamRNA/as-3'UTR) exhibit a reduction in the expression of TCR/CD3 complex and zeta protein on their cell surface as well as a reduction in the production of IL-2 after stimulation with anti-CD3 Ab compared with that in wild-type 3'UTR mutants (MA5.8 cells transfected with zetamRNA/w-3'UTR). Furthermore, the real-time PCR analyses demonstrated that the half-life of zetamRNA/as-3'UTR in AS3'UTR mutants (3 h) was much shorter than that of zetamRNA/w-3'UTR in wild-type 3'UTR mutants (15 h). Thus, the lower stability of zetamRNA/as-3'UTR, which is predominant in SLE T cells, may be responsible for the reduced expression of the TCR/CD3 complex, including zeta protein, in SLE T cells.     

Interferon inhibitor in the blood of patients with systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) patients at advanced stages of the disease have an interferon inhibitor in the blood circulation. This inhibitor can block antiviral activity of all three types of human interferons and can significantly reduce the synthesis of interferon alpha by the treated lymphocytes obtained from normal healthy individuals. Available evidence suggests that inhibitor activity is neither because of the antibody to interferon nor due to high level of protease-like activity in the plasma. The inhibitor has also been shown to be effective in eliminating the interferon-mediated enhancement of natural killer cell activity. Interferon inhibitory activity was not detected in any of the sera taken from normal healthy individuals. Identification and characterization of interferon inhibitor has direct bearing upon effective utilization of interferons in the clinic.     

Autoimmunity induced by human cytomegalovirus in patients with systemic lupus erythematosus

Human cytomegalovirus is a common herpesvirus that is linked to autoimmunity, especially in genetically predisposed persons. The article by Hsieh and colleagues in a previous issue of Arthritis Research & Therapy suggests that a C-terminal peptide of the human cytomegalovirus protein pp65 is highly immunogenic in patients with systemic lupus erythematosus and that antibodies against this peptide cross-react with nuclear proteins and double-stranded DNA, which are highly frequent autoantibodies in systemic lupus erythematosus patients. These observations highlight the fact that immunization with one small cytomegalovirus-specific peptide results in multiple autoreactive antibodies, probably through molecular mimicry and epitope spreading, in genetically predisposed persons.     

Predictors of clinical outcomes in patients with neuropsychiatric systemic lupus erythematosus

IntroductionNeuropsychiatric systemic lupus erythematosus (NPSLE), a serious organ disorder with a variety of symptoms, has diverse therapeutic outcomes because of the variability of NPSLE manifestations. A comprehensive association study of NPSLE among clinical and immunopathogenic aspects and outcomes has not been conducted.MethodsWe analyzed the laboratory data, NPSLE symptoms, and clinical outcomes at 1 yr post-treatment and the profiles of 27 cytokines, chemokines and growth factors in cerebrospinal fluid (CSF) samples using the Bio-Plex Human 27-plex panel from 28 NPSLE patients. Univariate and multivariable competing risks regression analyses were used to determine the predictive factors of clinical response. We also tried to predict the outcome of NPSLE by the 27 cytokines/chemokines/growth factors using a weighted-voting (WV) algorithm.ResultsOf the two males and 26 females (92.9%), 16 were non-responders at 1 yr post-treatment; in the final model, the independent predictors of non-responders were longer disease durations of SLE (odds ratio [OR]: 1.490, 95% confidence interval [CI]: 1.143–2.461, p = 0.0003) and patients with more than one NPSLE symptom types (OR: 15.14, 95% CI: 1.227–452.1, p = 0.0334). The pretreatment CSF interleukin (IL)-6, IL-10, interferon-gamma (IFN-γ) and tumor necrosis factor-alpha (TNF-α) levels were significantly higher in the non-responders (p = 0.0207, p = 0.0054, p = 0.0242 and p = 0.0077, respectively). We identified six “minimum predictive markers:” IL-10, TNF-α, IL-6, IFN-γ, IL-4 and IL-13 by a WV algorithm that showed the highest accuracy (70.83%) and highest Matthews correlation coefficient (54.23%).ConclusionsWe have devised a numerical prediction scoring system that was able to separate the non-responders from responders. The patients with longer disease durations of SLE and those with more than one NPSLE symptom types had poorer outcomes. Our findings may indicate both the importance of making a diagnosis at an earlier phase for better therapeutic response and the usefulness of measuring multiple cytokines to predict NPSLE therapeutic outcomes.     

SCE frequencies in lymphocytes of systemic lupus erythematosus patients

The frequency of sister-chromatid exchanges (SCEs) was investigated in peripheral lymphocytes of lupus erythematosus patients and compared with values obtained for healthy controls. Irrespective of the kind of medical treatment, an increased level of spontaneously occurring SCEs could be demonstrated in lupus patients. In addition to spontaneously occurring SCEs, mitomycin C (MMC)-induced SCEs were evaluated. No difference between patients and controls was found with respect to MMC-induced SCEs.