Identification of novel microRNA signatures linked to human lupus disease activity and pathogenesis: miR-21 regulates aberrant T cell responses through regulation of PDCD4 expression.

OBJECTIVE: MicroRNAs (miRNAs) regulate the expression of genes involved in immune activation. A study was undertaken to characterise the miRNA signature and identify novel genes involved in the regulation of immune responses in systemic lupus erythematosus (SLE). METHODS: The expression of 365 miRNAs in peripheral blood mononuclear cells of patients with SLE and healthy controls was analysed using TaqMan Low Density Arrays. The results were validated by quantitative real-time PCR and potential target genes were identified using prediction analysis software. The effect of miR-21 on T cell function was assessed by transfection with antago-miR-21 or pre-miR-21. RESULTS: A 27-miRNA signature was identified in patients with SLE; 19 miRNAs correlated with disease activity. Eight miRNAs were deregulated specifically in T cells and four miRNAs in B cells. miR-21 was upregulated and strongly correlated with SLE disease activity (r(2)=0.92). Compared with controls, CD4 T lymphocytes from patients with SLE had higher basal and activation-induced miR-21 expression. Silencing of miR-21 reversed the activated phenotype of T cells from patients with SLE--namely, enhanced proliferation, interleukin 10 production, CD40L expression and their capacity to drive B cell maturation into Ig-secreting CD19+CD38(hi)IgD-(plasma cells. Overexpression of mMiR-21 in normal T cells led to acquisition of an activated phenotype. Investigation of putative gene- targets showed that PDCD4 (a selective protein translation inhibitor) was suppressed by miR-21 and its expression was decreased in active SLE. CONCLUSIONS: miRNAs represent potential biomarkers in SLE as their expression reflects underlying pathogenic processes and correlates with disease activity. Upregulated miR-21 affects PDCD4 expression and regulates aberrant T cell responses in human SLE.

Hidradenitis suppurativa associated with Crohn's disease and spondyloarthropathy: response to anti-TNF therapy.

An association of hidradenitis suppurativa with Crohn's disease is supported by previous repent. We here report a patient with hidradenitis suppurativa who subsequently developed peripheral arthritis, sacroiliitis, and Crohn's disease. A significant attenuation of bowel, cutaneous, and joint symptoms was achieved after treatment with monoclonal antibody against tumor necrosis factor (TNF). The pathogenetic aspects according to the literature and response to the various therapeutic measures applied are also presented.

Modest but sustained increase of serum high density lipoprotein cholesterol levels in patients with inflammatory arthritides treated with infliximab.

OBJECTIVE: Tumor necrosis factor-a (TNF-a) is a key cytokine in the pathogenesis of chronic inflammatory arthritides, has proatherogenic effects, and may be positively correlated with impairment of the action of insulin. Patients with chronic inflammatory arthritides have an increased risk for cardiovascular diseases. We assessed whether anti-TNF-a treatment modifies the unfavorable lipid profile induced by chronic inflammatory arthritides. METHODS: Sixty patients (24 with rheumatoid arthritis, 26 ankylosing spondylitis, and 10 psoriatic arthritis) receiving infliximab because of ongoing disease activity despite disease modifying drugs (DMARD) were prospectively studied for 6 months. Lipid profile, total cholesterol/high density lipoprotein cholesterol (TC/HDL-C), and low density lipoprotein cholesterol (LDL-C)/HDL-C ratios, as well as disease activity indices (DAS28 and BASDAI), were assessed. RESULTS: A sustained increase of serum HDL-C was observed [mean increase (95% CI)] 5 (3-7) mg/dl, 3.5 (1-6) mg/dl, and 3 (1-5) mg/dl at 1, 3, and 6 months, respectively (p < 0.01). Compared to nonresponders, HDL-C increased significantly more in EULAR or BASDAI responders (0.8 vs 5.8 mg/dl; p = 0.05). Serum TC was significantly increased [11 (4-8) mg/dl; p = 0.001] only after the first month of treatment. TC/HDL-C and LDL-C/HDL-C decreased only after the first month [0.3 (0.1-0.4), p < 0.01, and 0.2 (0.1-0.4), p < 0.01, respectively]. For patients with baseline LDL-C > 130 mg/dl, LDL-C/HDL-C decreased (p < 0.05) during the whole study period and TC/HDL-C decreased (p < 0.05) at 1 and 3 months. CONCLUSION: Anti-TNF-a treatment in patients with chronic inflammatory arthritides induces a modest, but sustained, increase in serum HDL-C levels, which may have a favorable effect in reducing the cardiovascular risk in these patients.

Expansion of toll-like receptor 9-expressing B cells in active systemic lupus erythematosus: implications for the induction and maintenance of the autoimmune process.

OBJECTIVE: Toll-like receptors (TLRs) are pattern-associated receptors in innate immunity that may be involved in the recognition of self antigens and the production of pathogenic autoantibodies. This study was undertaken to examine the expression and function of various TLRs in subpopulations of peripheral blood mononuclear cells (PBMCs) of patients with systemic lupus erythematosus (SLE). METHODS: The expression of TLRs in PBMCs from 50 SLE patients with active disease (SLE Disease Activity Index [SLEDAI] score >or=8; n = 26) or inactive disease (SLEDAI score <8; n = 24) and 20 healthy controls was studied by flow cytometry. TLR expression was assessed on various subpopulations of PBMCs (TLR-2 and TLR-4 by membrane staining; TLR-3 and TLR-9 by intracellular staining). TLR function was accessed by stimulating PBMCs with specific ligands. RESULTS: The proportion of B cells and monocytes expressing TLR-9 was higher among patients with active SLE (mean +/- SD 49.5 +/- 24.4% and 30.7 +/- 24.1%, respectively) than among patients with inactive disease (22.8 +/- 19.6% and 14.3 +/- 8.4%, respectively; P = 0.02 and P = 0.03). Among B cells, the proportion of plasma cells and memory B cells expressing TLR-9 was increased in patients with active SLE. Increased percentages of TLR-9-expressing B cells correlated with the presence of anti-double-stranded DNA antibodies (P = 0.007). Treatment with serum from patients with active disease increased the percentage of TLR-9-expressing plasma cells in serum from healthy controls. Enhanced induction of HLA-DR after TLR-9 stimulation was documented in B cells from patients with active disease. CONCLUSION: In patients with active SLE, the proportion of peripheral blood memory B cells and plasma cells expressing TLR-9 is increased. Endogenous nucleic acids released during apoptotic cell death may stimulate B cells via TLR-9 and contribute to SLE pathogenesis.

Anemia of chronic disease in rheumatoid arthritis is associated with increased apoptosis of bone marrow erythroid cells: improvement following anti-tumor necrosis factor-alpha antibody therapy.

Circumstantial evidence has implicated tumor necrosis factor alpha (TNF-alpha) in the pathogenesis of anemia of chronic disease (ACD) in rheumatoid arthritis (RA). We investigated the role of TNF-alpha in erythropoiesis of patients with active RA (n = 40) and the effect of anti-TNF-alpha antibody administration (cA2). Patients with RA had lower numbers of CD34+/CD71+ and CD36-/glycophorin A+ (glycoA+) bone marrow (BM) cells and increased proportions of apoptotic cells within the CD34+/CD71+ and CD36+/glycoA+ cell compartments, compared to healthy controls (n = 24). Erythroid burst-forming units (BFU-Es) obtained by BM mononuclear or purified CD34+ cells were significantly lower in RA patients compared to controls. These abnormalities were more pronounced among patients with ACD. Increased TNF-alpha levels in patient long-term BM culture supernatants inversely correlated with BFU-Es and hemoglobin levels and positively with the percentage of apoptotic CD34+/CD71+ and CD36+/glycoA+ cells. Following cA2 therapy, a normalization was documented in the number of CD34+/CD71+ and CD36-/glycoA+ cells, the number of BFU-Es, and the proportion of apoptotic CD34+/CD71+ and CD36+/glycoA+ cells, which was associated with a significant increase in hemoglobin levels compared to baseline. Recovery from anemia was more prominent in patients with ACD. The exogenous addition of an anti-TNF-alpha antibody in the cultures increased BFU-E number in patients prior to cA2 treatment but not after treatment, further substantiating the inhibitory role of TNF-alpha on patients' erythropoiesis. We conclude that TNF-alpha-mediated apoptotic depletion of BM erythroid cells may account for ACD in RA and that cA2 administration may ameliorate ACD in these patients by down-regulating the apoptotic mechanisms involved in erythropoiesis.

Bone marrow progenitor cell reserve and function and stromal cell function are defective in rheumatoid arthritis: evidence for a tumor necrosis factor alpha-mediated effect.

Based on previous reports for impaired hematopoiesis in rheumatoid arthritis (RA), and in view of the current interest in exploring the role of autologous stem cell transplantation (ASCT) as an alternative treatment in patients with resistant disease, we have evaluated bone marrow (BM) progenitor cell reserve and function and stromal cell function in 26 patients with active RA. BM progenitor cells were assessed using flow cytometry and clonogenic assays in short-term and long-term BM cultures (LTBMCs). BM stroma function was assessed by evaluating the capacity of preformed irradiated LTBMC stromal layers to support the growth of normal CD34(+) cells. We found that RA patients exhibited low number and increased apoptosis of CD34(+) cells, defective clonogenic potential of BM mononuclear and purified CD34(+) cells, and low progenitor cell recovery in LTBMCs, compared with healthy controls (n = 37). Patient LTBMC stromal layers failed to support normal hematopoiesis and produced abnormally high amounts of tumor necrosis factor alpha (TNF alpha). TNF alpha levels in LTBMC supernatants inversely correlated with the proportion of CD34(+) cells and the number of colony-forming cells, and positively with the percentage of apoptotic CD34(+) cells. Significant restoration of the disturbed hematopoiesis was obtained following anti-TNF alpha treatment in 12 patients studied. We concluded that BM progenitor cell reserve and function and BM stromal cell function are defective in RA probably due, at least in part, to a TNF alpha-mediated effect. The role of these abnormalities on stem cell harvesting and engraftment in RA patients undergoing ASCT remains to be clarified.