Objective. Toll-like receptors (TLRs) are patternassociated 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 >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 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.
Objective. A putative regulatory intronic polymorphism (PD1.3) in the programmed death 1 (PD-1) gene, a negative regulator of T cells involved in peripheral tolerance, is associated with increased risk for systemic lupus erythematosus (SLE). We undertook this study to determine the expression and function of PD-1 in SLE patients.Methods. We genotyped 289 SLE patients and 256 matched healthy controls for PD1.3 by polymerase chain reaction-restriction fragment length polymorphism analysis. Expression of PD-1 and its ligand, PDL-1, was determined in peripheral blood lymphocytes and in renal biopsy samples by flow cytometry and immunohistochemistry. A crosslinker of PD-1 was used to assess its effects on anti-CD3/anti-CD28-induced T cell proliferation and cytokine production.Results. SLE patients had an increased frequency of the PD1.3 polymorphism (30.1%, versus 18.4% in controls; P ؍ 0.006), with the risk A allele conferring decreased transcriptional activity in transfected Jurkat cells. Patients homozygous for PD1.3-but not patients heterozygous for PD1.3-had reduced basal and induced PD-1 expression on activated CD4؉ T cells. In autologous mixed lymphocyte reactions (AMLRs), SLE patients had defective PD-1 induction on activated CD4؉ cells; abnormalities were more pronounced among homozygotes. PD-1 was detected within the glomeruli and renal tubules of lupus nephritis patients, while PDL-1 was expressed by the renal tubules of both patients and controls. PD-1 crosslinking suppressed proliferation and cytokine production in both normal and lupus T cells; addition of serum from patients with active SLE significantly ameliorated this effect on proliferation.Conclusion. SLE patients display aberrant expression and function of PD-1 attributed to both direct and indirect effects. The expression of PD-1/PDL-1 in renal tissue and during AMLRs suggests an important role in regulating peripheral T cell tolerance.
Systemic lupus erythematosus (SLE) is a multifactorial autoimmune rheumatic disease. Although its highest prevalence is among women of childbearing age, the disease is not confined within this population. A total of 15-20% of cases of SLE are diagnosed in children younger than 16 years (childhood-onset lupus). Although there have been few studies directly comparing childhood- to adult-onset lupus, there is substantial evidence to suggest that pediatric lupus patients display some differences in their disease profile compared with adult-onset populations. Overall, an increased male-to-female ratio, a higher prevalence of nephritis and CNS involvement necessitating a more sustained need for steroids and immnosuppressive drugs, and a higher prevalence of progression to end-stage renal disease are distinguishing features of childhood-onset lupus. In contrast, a higher prevalence of pulmonary involvement, arthritis and discoid lupus are reported in adult-onset SLE patients. Furthermore, childhood-onset lupus patients may experience a serious negative impact on their psychosocial and physical development, issues that pose extra challenges to healthcare providers. Growth delay, osteoporosis, the psychological effect of steroid-induced alterations of the physical image, and often poor treatment compliance are the issues that need to be addressed in pediatric lupus populations. In this review, we compare the epidemiological, clinical and laboratory features, and treatment options of childhood- and adult-onset lupus, and comment on the applicability of the instruments that measure activity, severity and cumulative disease damage in childhood-onset disease. In addition, we highlight special issues of concern for pediatric lupus patients, discussing the significance in the transition from pediatric to adult rheumatology care.
IntroductionBone marrow (BM) is an immunologically privileged site where activated autoantibody-producing B cells may survive for prolonged periods. We investigated the effect of rituximab (anti-CD20 mAb) in peripheral blood (PB) and BM B-cell and T-cell populations in active rheumatoid arthritis (RA) patients.MethodsActive RA patients received rituximab (1,000 mg) on days 1 and 15. PB (n = 11) and BM (n = 8) aspirates were collected at baseline and at 3 months. We assessed B-cell and T-cell populations using triple-color flow cytometry.ResultsRituximab therapy decreased PB (from a mean 2% to 0.9%, P = 0.022) but not BM (from 4.6% to 3.8%, P = 0.273) CD19+ B cells, associated with a significant reduction in the activated CD19+HLA-DR+ subset both in PB (from 55% to 19%, P = 0.007) and in BM (from 68% to 19%, P = 0.007). Response to rituximab was preceded by a significant decrease in PB and BM CD19+CD27+ memory B cells (P = 0.022). These effects were specific to rituximab since anti-TNF therapy did not reduce total or activated B cells. Rituximab therapy did not alter the number of activated CD4+HLA-DR+ and CD4+CD25+ T cells.ConclusionsRituximab therapy preferentially depletes activated CD19+HLA-DR+ B cells in the PB and BM of active RA patients. Clinical response to rituximab is associated with depletion of CD19+CD27+ memory B cells in PB and BM of RA patients.
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