Intrinsic T cell defects in systemic autoimmunity

Impaired innate and adaptive immune responses to BNT162b2 SARS-CoV-2 vaccination in systemic lupus erythematosus

Understanding the immune responses to SARS-CoV-2 vaccination is critical to optimizing vaccination strategies for individuals with autoimmune diseases, such as systemic lupus erythematosus (SLE). Here, we comprehensively analyzed innate and adaptive immune responses in 19 patients with SLE receiving a complete 2-dose Pfizer-BioNTech mRNA vaccine (BNT162b2) regimen compared with a control cohort of 56 healthy control (HC) volunteers. Patients with SLE exhibited impaired neutralizing antibody production and antigen-specific CD4+ and CD8+ T cell responses relative to HC. Interestingly, antibody responses were only altered in patients with SLE treated with immunosuppressive therapies, whereas impairment of antigen-specific CD4+ and CD8+ T cell numbers was independent of medication. Patients with SLE also displayed reduced levels of circulating CXC motif chemokine ligands, CXCL9, CXCL10, CXCL11, and IFN-γ after secondary vaccination as well as downregulation of gene expression pathways indicative of compromised innate immune responses. Single-cell RNA-Seq analysis reveals that patients with SLE showed reduced levels of a vaccine-inducible monocyte population characterized by overexpression of IFN-response transcription factors. Thus, although 2 doses of BNT162b2 induced relatively robust immune responses in patients with SLE, our data demonstrate impairment of both innate and adaptive immune responses relative to HC, highlighting a need for population-specific vaccination studies.

Metabolic Modulators in Cardiovascular Complications of Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a multifactorial disorder with contributions from hormones, genetics, and the environment, predominantly affecting young women. Cardiovascular disease is the primary cause of mortality in SLE, and hypertension is more prevalent among SLE patients. The dysregulation of both innate and adaptive immune cells in SLE, along with their infiltration into kidney and vascular tissues, is a pivotal factor contributing to the cardiovascular complications associated with SLE. The activation, proliferation, and differentiation of CD4+ T cells are intricately governed by cellular metabolism. Numerous metabolic inhibitors have been identified to target critical nodes in T cell metabolism. This review explores the existing evidence and knowledge gaps concerning whether the beneficial effects of metabolic modulators on autoimmunity, hypertension, endothelial dysfunction, and renal injury in lupus result from the restoration of a balanced immune system. The inhibition of glycolysis, mitochondrial metabolism, or mTORC1 has been found to improve endothelial dysfunction and prevent the development of hypertension in mouse models of SLE. Nevertheless, limited information is available regarding the potential vasculo-protective effects of drugs that act on immunometabolism in SLE patients.

Cordyceps proteins alleviate lupus nephritis through modulation of the STAT3/mTOR/NF-кB signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Cordyceps is a parasitic edible fungus, which is a unique Chinese medicinal material. It has been reported to have immunomodulatory effects and use in kidney disease. Especially, Cordyceps has been used in the treatment of lupus nephritis (LN).

AIM OF STUDY

Cordyceps proteins (CP) have a favorable bidirectional immunomodulatory functions and may have therapeutic potential for LN. However, the underlying molecular mechanism remains unknown. So this study aimed to examine the activities of CP in LN and possible mechanism.

MATERIALS AND METHODS

So proteomics was performed to detect proteins components of Cordyceps, and analysis it. In addition, MRL/lpr mice were used to study the progression of LN. The MRL/lpr mice were fed either CP (i.g, 0.5, 1.0, 1.5 g/kg/d), prednisolone acetate (PA, i.g, 6 mg/kg/d), or Bailing capsule (BC, i.g, 0.75 g/kg/d) for 8 weeks. Hematoxylin-eosin (H&E), Periodic Acid Schif (PAS) and Masson's stainings, Immunofluorescence, and Immunohistochemistry were performed to verify the therapeutic effect of CP on MRL/lpr mice. The mechanism by CP alimerated LN was uncovered by Western blotting (WB) and Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) methods.

RESULTS

Our results revealed that CP blocked proteinuria production and renal inflammatory infiltratation in MRL/lpr mice to reduce the renal fibrosis. In addition, CP worked better than BC which is artificial Cordyceps fungus powder in regulating proteinuria to urine creatinine ratio and interleukin-4(IL-4) protein amount. Especially, CP modulated the STAT3/mTOR/NF-кB signaling pathway in LN mice and brought a more pronounced lowering effect on the contents of IL-6 and IL-1β than the PA.

CONCLUSION

CP could be a potential anti-inflammatory immune product with strong regulatory effects and potency than BC and PA in nephritis therapeutics.

First-degree relatives of patients with systemic lupus erythematosus: Autoreactivity but not autoimmunity?

BACKGROUND

Systemic lupus erythematosus (SLE) is a disorder with a complex immunopathogenesis. It is well known that the disease begins with immunological alterations and autoantibody appearance in the serum years before clinical onset. As SLE has a strong tendency to familial aggregation, first-degree relatives (FDRs) constitute a group at elevated risk. The current understanding is that external risk factors trigger underlying immune dysregulations, leading to overt disease in those with elevated genetic risk.

OBJECTIVE

This cross-sectional study investigates the degree to which clinical features, external risk factors, and immunological profiles differ in SLE FDRs from healthy individuals and SLE patientts.

METHODS

Three groups were studied: Lupus patient FDRs (n = 56), healthy controls (n = 20), and SLE patients (n = 20). FDRs and healthy participants completed a detailed clinical questionnaire that included questions regarding smoking and estrogen drug history. All participants were tested for the presence of the following antinuclear autoantibodies (ANAs) against: nRNP/Sm, Sm, Ro60, Ro-52, La, Scl-70, PM-Scl, PM- Scl, Jo-1, CENP B, PCNA, dsDNA, nucleosomes, histones, RibP, AMA M2, DFS70, and eight soluble cytokines, including transforming growth factor-β (TGF-β), vitamin D levels, and antibodies against Epstein-Barr virus (EBV).

RESULTS

Compared with the healthy controls, FDRs had higher titers of ANA, more specific staining immunofluorescent patterns, and more autoantibody specificities. Furthermore, FDRs differed significantly in their TGF-β levels from the other two groups. In FDRs, some clinical features (hair loss, skin, and oral ulcer-like lesions) were associated with higher ANA titers and some (oral ulcer-like lesions) with the anti-Ro60-specific antibody. Interestingly, there was an association between ANA titers and levels of antibodies against EBV only in the FDR group.

CONCLUSION

First-degree relatives display unique clinical and immunological profiles, placing them between healthy individuals and SLE patients, with a balance between compensated immune dysregulation and disease-developing potential. A possible association between ANA titer and the number of clinical complaints is observed, which needs to be confirmed in more extensive studies.

Paeoniflorin Inhibits LPS-Induced Activation of Splenic CD4+ T Lymphocytes and Relieves Pathological Symptoms in MRL/lpr Mice by Suppressing IRAK1 Signaling

Interleukin-1receptor-associated kinase 1 (IRAK1) plays a critical role in systemic lupus erythematosus (SLE). It was reported that SLE was associated with an inflammatory response mediated by defective immune tolerance, including overproduction of autoantibodies, chronic inflammation, and organ damage. Previous reports stated paeoniflorin (PF) had an immunosuppressive effect. The purpose of this study was to determine the anti-inflammatory effect of PF in SLE and its underlying mechanisms. Followed by induced with lipopolysaccharide (LPS), the splenocytes and the isolated CD4+ T lymphocytes of MRL/lpr mice were divided into three groups: control group, LPS group, and LPS + PF group, respectively. MRL/MP mice were used as the control group (treated with distilled water). The MRL/lpr mice were randomly divided into three groups: the model group (treated with distilled water), the prednisone group, and the PF group. The MRL/lpr mice were treated with prednisone acetate (5 mg/kg) and PF (25, 50, and 75 mg/kg) for eight weeks. Subsequently, ELISA, qRT-PCR, western blotting, HE, and Masson staining were performed to detect various indicators. The results of Cell Counting Kit-8 (CCK-8) showed that 10 μg/mL of LPS had the optimum effect on cell viability, and 50 μmol/L of PF had no obvious cytotoxicity to LPS-treated cells. PF reduced the expression level of IRAK1-nuclearfactor-κB (NF-κB) and its downstream inflammatory cytokines in the splenocytes and CD4+ T lymphocytes of MRL/lpr mice stimulated by LPS, especially in the latter. The serum antibody contents in the PF group mice were reduced, and the kidney damage was also alleviated accordingly. Moreover, the IRAK1/inhibitor of the nuclear factor-κB kinase (IKK)/NF-κB inhibitor (IκB)/NF-κB pathways was found to be involved in the anti-inflammation effect of PF in the kidney and spleen. In conclusion, it is thought that PF may have the potential to be used as a therapeutic agent to reduce the inflammatory activity of SLE. Inhibition of the IRAK1-NF-κB pathway may help formulate novel therapeutic tactics for SLE.

Polymeric dexamethasone prodrugs attenuate lupus nephritis in MRL/lpr mice with reduced glucocorticoid toxicity

Due to their potent immunosuppressive and anti-inflammatory effects, glucocorticoids (GCs) are the most widely used medications in treating lupus nephritis (LN). Long-term use of GCs, however, is associated with numerous off-target adverse effects. To reduce GCs' adverse effects, we previously developed two polymeric dexamethasone prodrug nanomedicines: N-(2-hydroxypropyl) methacrylamide (HPMA) copolymer-based dexamethasone prodrug (P-Dex), and micelle-forming polyethylene glycol (PEG)-based dexamethasone prodrug (ZSJ-0228). Both P-Dex and ZSJ-0228 provided sustained amelioration of LN in lupus-prone NZB/W F1 mice with reduced GC-associated adverse effects. Here, we have extended our investigation to the MRL/lpr mouse model of LN. Compared to dose equivalent daily dexamethasone sodium phosphate (Dex) treatment, monthly P-Dex or ZSJ-0228 treatments were more effective in reducing proteinuria and extending the lifespan of MRL/lpr mice. Unlike the daily Dex treatment, ZSJ-0228 was not associated with measurable GC-associated adverse effects. In contrast, adrenal gland atrophy was observed in P-Dex treated mice.

Association of Epstein-Barr virus infection with systemic lupus erythematosus in Taiwan

An association between Epstein-Barr virus (EBV) infection and systemic lupus erythematosus (SLE) has been suggested from previous serologic evidence. Since most adults in Taiwan are EBV-infected, seroepidemiologic studies based on standard assays for EBV are unlikely to dissociate SLE patients and control groups. We reexamine this question by using novel methodologies in which IgA anti-EBV-coded nuclear antigens-1 (EBNA-1) and IgG anti-EBV DNase antibodies were analysed by ELISA, and EBV viral loads were detected by real-time quantitative PCR for 93 adult SLE patients and 370 age-, sex- and living place-matched healthy controls in Taiwan. The specificities of antibodies for extractible nuclear antigens were determined by Western blot. Our results show that IgA anti-EBV EBNA1 antibodies were detectable in 31.2% SLE patients but only in 4.1% of controls (odds ratio [OR] = 10.72, 95% confidence interval [CI] = 5.19–22.35; P < 10-7), IgG anti-EBV DNase antibodies were detected in 53.8% SLE patients but only in 12.2% controls (OR = 8.40, 95% CI = 4.87–14.51; P < 10-7). EBV DNA was amplifiable from the sera of 41.9% SLE patients but from only 3.24% controls ( P < 0.05). A significant association of IgG anti-EBV DNase antibodies with anti-Sm/RNP antibodies was observed ( P < 0.005). The higher seroreactivity and higher copy numbers of EBV genome indicated association of EBV infection with SLE in Taiwan.

Normalization of CD4+ T cell metabolism reverses lupus

Systemic lupus erythematosus (SLE) is an autoimmune disease in which autoreactive CD4(+) T cells play an essential role. CD4(+) T cells rely on glycolysis for inflammatory effector functions, but recent studies have shown that mitochondrial metabolism supports their chronic activation. How these processes contribute to lupus is unclear. We show that both glycolysis and mitochondrial oxidative metabolism are elevated in CD4(+) T cells from lupus-prone B6.Sle1.Sle2.Sle3 (TC) mice as compared to non-autoimmune controls. In vitro, both the mitochondrial metabolism inhibitor metformin and the glucose metabolism inhibitor 2-deoxy-d-glucose (2DG) reduced interferon-γ (IFN-γ) production, although at different stages of activation. Metformin also restored the defective interleukin-2 (IL-2) production by TC CD4(+) T cells. In vivo, treatment of TC mice and other lupus models with a combination of metformin and 2DG normalized T cell metabolism and reversed disease biomarkers. Further, CD4(+) T cells from SLE patients also exhibited enhanced glycolysis and mitochondrial metabolism that correlated with their activation status, and their excessive IFN-γ production was significantly reduced by metformin in vitro. These results suggest that normalization of T cell metabolism through the dual inhibition of glycolysis and mitochondrial metabolism is a promising therapeutic venue for SLE.

Inhibition of PI3Kδ reduces kidney infiltration by macrophages and ameliorates systemic lupus in the mouse

Systemic lupus erythematosus (SLE) is a human chronic inflammatory disease generated and maintained throughout life by autoreactive T and B cells. Class I phosphoinositide 3-kinases (PI3K) are heterodimers composed of a regulatory and a catalytic subunit that catalyze phosphoinositide-3,4,5-P3 formation and regulate cell survival, migration, and division. Activity of the PI3Kδ isoform is enhanced in human SLE patient PBLs. In this study, we analyzed the effect of inhibiting PI3Kδ in MRL/lpr mice, a model of human SLE. We found that PI3Kδ inhibition ameliorated lupus progression. Treatment of these mice with a PI3Kδ inhibitor reduced the excessive numbers of CD4(+) effector/memory cells and B cells. In addition, this treatment reduced serum TNF-α levels and the number of macrophages infiltrating the kidney. Expression of inactive PI3Kδ, but not deletion of the other hematopoietic isoform PI3Kγ, reduced the ability of macrophages to cross the basement membrane, a process required to infiltrate the kidney, explaining MRL/lpr mice improvement by pharmacologic inhibition of PI3Kδ. The observations that p110δ inhibitor prolonged mouse life span, reduced disease symptoms, and showed no obvious secondary effects indicates that PI3Kδ is a promising target for SLE.

Identification of microRNA-31 as a novel regulator contributing to impaired interleukin-2 production in T cells from patients with systemic lupus erythematosus

OBJECTIVE

MicroRNAs (miRNAs) function to fine-tune the control of immune cell signaling. It is well established that there are abnormalities in the interleukin-2 (IL-2)-related signaling pathways in systemic lupus erythematosus (SLE). The miR-31 microRNA has been found to be markedly underexpressed in patients with SLE, and thus the present study was undertaken to investigate the role of miR-31 in IL-2 defects in lupus T cells.

METHODS

Expression levels of miR-31 were quantitated using TaqMan miRNA assays. Transfection and stimulation of cultured cells followed by TaqMan quantitative polymerase chain reaction, enzyme-linked immunosorbent assay, and reporter gene assays were conducted to determine the biologic function of miR-31. NF-AT nuclear translocation and expression were quantitatively measured using an ImageStream cytometer. Bioinformatics analysis, small interfering RNA (siRNA) knockdown, and Western blotting were performed to validate miR-31 targets and effects.

RESULTS

The expression of miR-31 was significantly decreased in lupus T cells, and this was positively correlated with the expression of IL-2. Overexpression of miR-31 in T cells increased the production of IL-2 by altering NF-AT nuclear expression and IL2 promoter activity, while knockdown of endogenous miR-31 reduced IL-2 production. RhoA expression was directly repressed by miR-31 in T cells. Of note, siRNA-mediated knockdown of RhoA enhanced IL2 promoter activity and, consequently, up-regulated IL-2 production. RhoA expression was consistently up-regulated and negatively correlated with the levels of miR-31 in lupus T cells. Manipulation of miR-31 expression in lupus T cells restored the expression of IL-2 at both the messenger RNA and protein levels.

CONCLUSION

MicroRNA-31 is a novel enhancer of IL-2 production during T cell activation. Dysregulation of miR-31 and its target, RhoA, could be a novel molecular mechanism underlying the IL-2 deficiency in patients with SLE.

Lupus autoimmunity altered by cellular methylation metabolism

Modifications of both DNA and protein by methylation are key factors in normal T and B cell immune responses as well as in the development of autoimmune disease. For example, the failure to maintain the methylation status of CpG dinucleotides in DNA triggers T cell autoreactivity. Methylated proteins are known targets of autoimmunity, including the symmetrical dimethylarginine residues of SmD1 and SmD3 in SLE. Herein, we demonstrate that altering the metabolism of S-adenosylmethionine (SAM), the major methyl donor for transmethylation reactions, can suppress T cell immunity. A by-product of SAM metabolism, 5'-deoxy-5'-methylthioadenosine (MTA), and an indirect inhibitor of methyltransferases, inhibits T cell responses including T cell activation markers, Th1/Th2 cytokines and TCR-related signaling events. Moreover, treatment of the lupus-prone MRL/lpr mouse with MTA markedly ameliorates splenomegaly, lymphadenopathy, autoantibody titers as well as IgG deposition and cellular infiltration in the kidney. Incubation of cells with SAM, which increases intracellular MTA levels, inhibits both TCR-mediated T cell proliferation and BCR (anti-IgM)-triggered B cell proliferation in a dose-dependent manner. These studies define the central role of MTA and SAM in immune responses and provide a simple approach to altering lymphocyte transmethylation and T cell mediated autoimmune syndromes.

Complement fragment C3d is colocalized within the lipid rafts of T cells and promotes cytokine production

The complement system plays an important role in tissue inflammation and damage in SLE patients. High levels of C3d were detected on the surface of erythrocytes and lymphocytes of SLE patients. The objective of this study was to assess the functional consequences of C3d fragments deposited on the surface membrane of SLE T cells. Methods: 46 SLE patients, 43 patients with other autoimmune diseases (OAD) and 33 healthy individuals (N) were enrolled in this study. T cells were isolated from peripheral blood and flow cytometry studies were conducted to assess the levels of C3d fragments, Ca++ influx responses and cytokine production. Confocal microscopy was used to study co-localized molecules. Student’s t-test was performed to determine statistical significance among study groups. Results: A significant percentage of the SLE T cells were found to be positive for C3d (13.58 ± 3.92%) when compared with normal T cells (4.52 ± 2.92%) ( p < 0.0000547) and T cells from patients with other autoimmune diseases (6.31 ± 4.57%) ( p < 0.00513). Peak Ca++ influx responses were significantly higher in C3d− SLE T cells compared with C3d+ SLE T cells ( p < 0.011). C3d+ T cells produced significantly more IL-2, IFN-gamma, IL-4 and IL-17. In contrast to the increased production of IL-2 by the C3d+ T cells, the overall SLE T cell population produced less IL-2 when compared with T cells from normal individuals or patients with other autoimmune disease. The C3d fragments were found to be localized within the lipid rafts. Conclusion: C3d fragments are localized in the lipid rafts of SLE T cells and contribute to abnormal T cell function by modulating Ca++ influx responses and increased cytokine production.

Administration of fasudil, a ROCK inhibitor, attenuates disease in lupus-prone NZB/W F1 female mice

Accumulating evidence from murine studies suggests that the RhoA/ROCK pathway plays an important role in the development of autoimmune disorders. We previously demonstrated that ROCK inhibition ameliorates disease in MRL/lpr mice, a spontaneous model of lupus. This study aimed to explore the protective effects of the ROCK inhibitor fasudil in a distinct model of lupus, NZB/W F1 female mice, to assess the broad applicability of ROCK inhibition for the treatment of lupus. NZB/W F1 female mice were administered fasudil continuously in their drinking water starting at 18 or 24 weeks of age up until 44 weeks of age, or remained untreated. Fasudil treatment significantly improved survival and decreased proteinuria, particularly when treatment was started at 18 weeks. There was also a significant decrease in serum anti-dsDNA autoantibody production, glomerular IgG and C3 deposition, and glomerulonephritis. Analysis of the splenic lymphocyte compartment revealed reduced effector/memory CD4(+) T cell and plasma cell numbers in fasudil treated mice while the frequency of other B cell and T cell subsets was unchanged. These results thus indicate that fasudil can ameliorate disease in NZB/W F1 female mice, suggesting that ROCK inhibition might be broadly effective for the treatment of lupus.

Pre-B cell leukemia homeobox 1 is associated with lupus susceptibility in mice and humans

Sle1a.1 is part of the Sle1 susceptibility locus, which has the strongest association with lupus nephritis in the NZM2410 mouse model. In this study, we show that Sle1a.1 results in the production of activated and autoreactive CD4(+) T cells. Additionally, Sle1a.1 expression reduces the peripheral regulatory T cell pool, as well as induces a defective response of CD4(+) T cells to the retinoic acid expansion of TGF-β-induced regulatory T cells. At the molecular level, Sle1a.1 corresponds to an increased expression of a novel splice isoform of Pbx1, Pbx1-d. Pbx1-d overexpression is sufficient to induce an activated/inflammatory phenotype in Jurkat T cells and to decrease their apoptotic response to retinoic acid. PBX1-d is expressed more frequently in the CD4(+) T cells from lupus patients than from healthy controls, and its presence correlates with an increased central memory T cell population. These findings indicate that Pbx1 is a novel lupus susceptibility gene that regulates T cell activation and tolerance.

Increased expression and phosphorylation of the two S100A9 isoforms in mononuclear cells from patients with systemic lupus erythematosus: a proteomic signature for circulating low-density granulocytes

Proteins differentially expressed in peripheral blood mononuclear cells (PBMCs) from systemic lupus erythematosus (SLE) patients versus Normal controls were identified by 2-DE and MALDI-MS. Thus, S100A9 expression was significantly increased in SLE PBMCs relative to Normal PBMCs at both mRNA and protein levels. Increased S100A9 levels in SLE PBMCs correlated positively with the abnormal presence of low-density granulocytes (LDGs) detected by flow-cytometry in the mononuclear cell fractions. Another set of proteins that were differentially expressed in SLE PBMCs formed S100A9-independent clusters, suggesting that these differences in protein expression are in fact reflecting changes in the abundance of specific cell types. In SLE PBMCs spots of the two S100A9 isoforms, S100A9-l and S100A9-s, and their phosphorylated counterparts were identified and confirmed to be phosphorylated at Thr(113) by MS/MS analyses. In addition, the phorbol ester PMA alone or in combination with ionomycin induced a stronger increase in threonine phosphorylation of S100A9 in SLE than in Normal PBMCs, while the same stimuli caused the opposite effect on phosphorylation and activation of Erk1/2, suggesting the existence of an abnormal S100A9 signaling in SLE PBMCs. Therefore, the expansion and activation of LDGs in SLE seems to underlie this prominent S100A9 signature.

T cell clonal expansions detected in patients with primary biliary cirrhosis express CX3CR1

The intrahepatic biliary destruction of primary biliary cirrhosis (PBC) appears secondary to a multi-lineage response that includes autoantibodies, biliary apotopes, and cellular responses. Although there has been considerable effort in defining the role and specificity of anti-mitochondrial autoantibodies, a major challenge has been the characterization of T effector pathways. This difficulty is due in part to the limitation of current technologies for directly isolating and characterizing autoreactive T cells from patients. Herein, we successfully demonstrate a novel technology for characterizing the surface phenotype of T cell oligoclonal expansions directly ex vivo. Using PBC as a prototypic disease we were able to detect clonal T cell expansions in 15/15 patients examined. Although the T cell expansions from different patients expressed different TCRVβ gene segments, the surface phenotype of the cells was the same. The clonal T cell expansions in PBC patients are CX3CR1(+) Fas(+) effector-memory T cells, a finding of particular importance given the known up-regulation of fractalkine on injured biliary epithelial cells (BEC). In contrast to the persistent aberrantly expanded T cells observed in the PBC patients, T cell expansions detected in response to a herpes viral infection were very dynamic and resolved over time. This protocol can be used to characterize T cell expansions in other autoimmune diseases.

Customising an antibody leukocyte capture microarray for systemic lupus erythematosus: beyond biomarker discovery

Systemic lupus erythematosus (SLE) is a complex autoimmune disease that has heterogeneous clinical manifestation with diverse patterns of organ involvement, autoantibody profiles and varying degrees of severity of disease. Research and clinical experience indicate that different subtypes of SLE patients will likely benefit from more tailored treatment regimes, but we currently lack a fast and objective test with high enough sensitivity to enable us to perform such sub-grouping for clinical use. In this article, we review how proteomic technologies could be used as such an objective test. In particular, we extensively review many leukocyte surface markers that are known to have an association with the pathogenesis of SLE, and we discuss how these markers can be used in the further development of a novel SLE-specific antibody leukocyte capture microarray. In addition, we review some bioinformatics challenges and current methods for using the data generated by these cell-capture microarrays in clinical use. In a broader context, we hope our experience in developing a disease specific cell-capture microarray for clinical application can be a guide to other proteomic practitioners who intend to extend their technologies to develop clinical diagnostic and prognostic tests for complex diseases.

Th17 cells in rheumatoid arthritis and systemic lupus erythematosus

Recent work has implicated a novel Th effector cell subset, the Th17 cell subset, in the development of both rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) because of the ability of Th17 cells to produce cytokines like IL-17 and IL-21 that can drive both inflammatory and humoral responses. In this review, we will discuss recent studies that have begun elucidating the factors that regulate the development of Th17 cells and provide a brief overview of the role of Th17 cells in RA and SLE.

Differential expression and molecular associations of Syk in systemic lupus erythematosus T cells

Diminished expression of TCR zeta and reciprocal up-regulation and association of FcRgamma with the TCR/CD3 complex is a hallmark of systemic lupus erythematosus (SLE) T cells. In this study we explored whether differential molecular associations of the spleen tyrosine kinase Syk that preferentially binds to FcRgamma contribute to pathological amplification of signals downstream of this "rewired TCR" in SLE. We detected higher amounts of Syk expression and activity in SLE compared with normal T cells. Selective inhibition of the activity of Syk reduced the strength of TCR-induced calcium responses and slowed the rapid kinetics of actin polymerization exclusively in SLE T cells. Syk and ZAP-70 also associated differently with key molecules involved in cytoskeletal and calcium signaling in SLE T cells. Thus, while Vav-1 and LAT preferentially bound to Syk, phospholipase C-gamma1 bound to both Syk and ZAP-70. Our results show that differential associations of Syk family kinases contribute to the enhanced TCR-induced signaling responses in SLE T cells. Thus, we propose molecular targeting of Syk as a measure to control abnormal T cell responses in SLE.

Proteomic analysis of plasma from patients with systemic lupus erythematosus: increased presence of haptoglobin alpha2 polypeptide chains over the alpha1 isoforms

In the present study plasma samples from 15 systemic lupus erythematosus (SLE) patients and 16 healthy controls of initially unknown haptoglobin (Hp) phenotype were separated by 2-DE, and tryptic digests of the excised Hpalpha polypeptide chain spots were analyzed by MALDI-TOF-MS. Selected tryptic peptides were sequenced by nano-(n)ESI-IT MS/MS. The six major Hp phenotypes were present, although with distinct frequencies in controls and SLE patients. Thus, there were an increased proportion of SLE patients with Hp 2-2, or Hp 2-1S phenotypes. The Hp phenotype distribution resulted in allele frequencies of 0 625 (Hp(2)), 0.281 (Hp(1S)), and 0.093 (Hp(1F)) in healthy controls, correlating fairly well with the allele frequencies of European populations. In contrast, the Hp allele frequencies of the SLE patients were 0.733 (Hp(2)), 0.233 (Hp(1S)), and 0.033 (Hp1(1F)), which clearly indicated an increased frequency of Hp(2), a similar proportion of Hp(1S) and a diminished proportion of Hp(1F) in SLE patients compared with that in healthy controls. Preferential Hpalpha2 expression in SLE patients may contribute to some of the clinical manifestations of the disease such as hypergammaglobulinemia, systemic vasculitis, and cardiovascular disorders.

Estrogen and CD4+ T cells

PURPOSE OF REVIEW

Many autoimmune rheumatic autoimmune disorders predominantly affect women. Sex hormones, in particular estrogen, can influence CD4 T-helper development and function. We highlight recent studies that begin to provide insights into the mechanisms by which estrogen modulates CD4 T-cell development and function, and thus potentially contribute to disease pathogenesis.

RECENT FINDINGS

High levels of estrogen can lead to thymic atrophy. Recent studies showed that this phenomenon results from effects of estrogen at multiple stages in early T-cell development. Estrogen is also known to affect mature CD4 T-cell function, and, in particular, their ability to produce selected cytokine profiles. The mechanisms by which estrogen can exert these effects were also recently explored and shown to include effects on expression of critical molecules known to be involved in these processes.

SUMMARY

Dissecting the molecular pathways employed by estrogen to modulate CD4 T cells will be critical in elucidating the manner by which estrogen exerts its effects on this compartment. Given that cell type specific differences underlie the ability of many hormonal therapies to exert tissue-specific estrogenic or antiestrogenic activities, this knowledge will be crucial to further exploitation of hormonal therapies in rheumatic autoimmune diseases.

Intracellular protein modification associated with altered T cell functions in autoimmunity

Posttranslational protein modifications influence a number of immunologic responses ranging from intracellular signaling to protein processing and presentation. One such modification, termed isoaspartyl (isoAsp), is the spontaneous nonenzymatic modification of aspartic acid residues occurring at physiologic pH and temperature. In this study, we have examined the intracellular levels of isoAsp residues in self-proteins from MRL(+/+), MRL/lpr, and NZB/W F(1) mouse strains compared with nonautoimmune B10.BR mice. In contrast to control B10.BR or NZB/W mice, the isoAsp content in MRL autoimmune mice increased and accumulated with age in erythrocytes, brain, kidney, and T lymphocytes. Moreover, T cells that hyperproliferate to antigenic stimulation in MRL mice also have elevated intracellular isoAsp protein content. Protein l-isoaspartate O-methyltransferase activity, a repair enzyme for isoAsp residues in vivo, remains stable with age in all strains of mice. These studies demonstrate a role for the accumulation of intracellular isoAsp proteins associated with T cell proliferative defects of MRL autoimmune mice.

Modulation of CR1 transcript in systemic lupus erythematosus (SLE) by IFN-gamma and immune complex

Reduced expression of Erythrocyte Complement Receptor 1 (E-CR1) is envisaged to contribute significantly to the pathophysiology of systemic lupus erythematosus (SLE). We determined the levels of CR1 transcript in the neutrophils from 25 untreated patients with active SLE and 25 normal healthy individuals and, studied the effect of interferon-gamma (IFN-gamma), interleukin-4 (IL-4) and immune complexes (IC) on the same. The study revealed a marked decline in the levels of neutrophil CR1 (N-CR1) transcript in the patients with SLE, and differential pattern of IFN-gamma and IL-4 expression in the neutrophils from normals and patients. Opsonized immune complexes down regulated CR1 transcript in patients and IFN-gamma up regulated the same both in normals and patients. Immune complexes suppressed this effect of IFN-gamma. IL-4 also suppressed the effect of IFN-gamma but effect confined only to the normals. This is the first real-time RT-PCR data comparing the neutrophil CR1 expression in normals and patients with SLE and its modulation by IFN-gamma, IL-4 and immune complexes. IFN-gamma and immune complexes, respectively, emerged as the positive and negative modulators of neutrophil CR1 transcript in SLE.

Increased association of CD38 with lipid rafts in T cells from patients with systemic lupus erythematosus and in activated normal T cells

In this study we have determined whether there is a relationship between CD38 expression on T cells, its distribution in different membrane microdomains, and T cell activation in SLE patients. The data show that CD38 expression is augmented in ex vivo CD3+, CD4+, CD8+, and CD25+ SLE T cells, which correlates with its increased insolubility in Brij 98 detergent, and its translocation into lipid rafts. Moreover, SLE T cells show an altered CD4:CD8 ratio, which is due to a decreased proportion of CD4+ T cells and a concomitant increase in the proportion of CD8+ T cells. These data are consistent with the increased CD38 expression and lipid raft formation, and the significant reduction in the CD4:CD8 ratio observed in mitogen-stimulated normal T cells as compared with that in ex vivo untouched normal T cells. Increased expression of CD38 in floating rafts from SLE T cells, or from activated normal T cells may modulate TCR signaling by providing or sequestering signaling molecules to the engaged TCR.

Loss of IRF-4-binding protein leads to the spontaneous development of systemic autoimmunity

IFN regulatory factor 4-binding (IRF-4-binding) protein (IBP) is a novel type of activator of Rho GTPases that is recruited to the immunological synapse upon TCR stimulation. Here we demonstrate that loss of IBP leads to the spontaneous development of a systemic autoimmune disorder characterized by the accumulation of effector/memory T cells and IgG+ B cells, profound hypergammaglobulinemia, and autoantibody production. Similar to human SLE, this syndrome primarily affects females. T cells from IBP-deficient mice are resistant to death in vitro as well as in vivo and exhibit selective defects in effector function. In the absence of IBP, T cells respond suboptimally to TCR engagement, as demonstrated by diminished ERK1/2 activation, decreased c-Fos induction, impaired immunological synapse formation, and defective actin polymerization. Transduction of IBP-deficient T cells with a WT IBP protein, but not with an IBP mutant lacking the Dbl-like domain required for Rho GTPase activation, rescues the cytoskeletal defects exhibited by these cells. Collectively, these findings indicate that IBP, a novel regulator of Rho GTPases, is required for optimal T cell effector function, lymphocyte homeostasis, and the prevention of systemic autoimmunity.

Abnormal differentiation of memory T cells in systemic lupus erythematosus

OBJECTIVE

The chemokine receptor CCR7 and the tumor necrosis factor receptor family member CD27 define 3 distinct, progressively more differentiated maturational stages of CD4 memory subpopulations in healthy individuals: the CCR7+, CD27+, the CCR7-, CD27+, and the CCR7-, CD27- populations. The goal of this study was to examine maturational disturbances in CD4 T cell differentiation in systemic lupus erythematosus (SLE), using these phenotypic markers.

METHODS

Phenotypic analysis by flow cytometry, in vitro stimulation experiments, telomere length measurement, and determination of inducible telomerase were carried out. RESULTS. In SLE patients, significant increases of CCR7-, CD27- and CCR7-, CD27+ and a reduction of CCR7+, CD27+ CD4 memory T cells were found. In vitro stimulation of SLE T cells showed a stepwise differentiation from naive to CCR7+, CD27+ to CCR7-, CD27+ to CCR7-, CD27-; telomere length and inducible telomerase decreased in these subsets in the same progressive sequence. The in vitro proliferative response of these populations progressively declined as their susceptibility to apoptosis increased. Interestingly, a significant reduction in inducible telomerase was noted in SLE naive and CCR7+, CD27+ CD4+ memory T cells. Additionally, SLE CCR7-, CD27+ and CCR7-, CD27- CD4 memory T cells proliferated poorly in response to in vitro stimulation and underwent significantly more apoptosis than their normal counterparts. Finally, expression of CXCR4 was significantly reduced in all SLE subsets compared with normal.

CONCLUSION

Together these data indicate an increased degree of in vivo T cell stimulation in SLE, resulting in the accumulation of terminally differentiated memory T cells with a decreased proliferative capacity and an increased tendency to undergo apoptosis upon stimulation.

New insights from murine lupus: disassociation of autoimmunity and end organ damage and the role of T cells

PURPOSE OF REVIEW

This review summarizes current literature on genetic regulation of different phenotypes in systemic lupus erythematosus in context of end-organ disease. Recent findings conflicting with the current paradigm that loss of tolerance to chromatin is the critical step for end-organ injury are discussed.

RECENT FINDINGS

Systemic lupus erythematosus is a prototype immune complex disease with circulating autoantibodies to chromatin, histone proteins, Sm/La, and other nuclear and cytoplasmic proteins. Extensive studies have been carried out on the regulation of B-cell and autoantibody production in lupus mice. However, the hypothesis that autoantibodies are primary mediators of organ damage fails to explain the heterogenous presentation in patients. Studies in murine models of systemic lupus erythematosus clearly dissociate genetic control of autoantibody responses to classic lupus antigens and kidney disease. There is increasing evidence to support the role of autoreactive T cells and genetic control of end organ susceptibility. These studies suggest complex interactions between innate and adaptive immunity resulting in end-organ damage. This review focuses on autoimmune responses and renal involvement in spontaneous systemic lupus erythematosus using murine models of lupus nephritis.

SUMMARY

Studies in murine models demonstrate complex genetic interactions regulating spontaneous systemic lupus erythematosus. Although detection of serum autoantibodies is considered a hallmark for clinical diagnosis of systemic lupus erythematosus, recent evidence shows that autoantibodies to classic lupus antigens are neither required nor sufficient for end-organ damage. Thus, murine models provide new insights into the pathogenesis of systemic lupus erythematosus.

Phenotypic and functional analysis of EBV-specific memory CD8 cells in SLE

T cell dysfunction has been described in systemic lupus erythematosus (SLE). However, the specific phenotype and function of antigen-specific CD8 cells is less clear. Here we determined phenotype and function of Epstein-Barr virus (EBV)-specific CD8 cells at the single-cell level in SLE. HLA-A2-restricted EBV-BMLF-1-specific CD8 cells were enumerated by flow cytometry using tetramers in SLE and healthy control subjects. Antigen-specific CD8 cells were analyzed for expression of differentiation, activation, proliferation, and anti-apoptotic markers. EBV-specific, other virus-specific (specific against a viral peptide pool consisting of cytomegalovirus, EBV and influenza virus peptides), and mitogen-induced CD8 cell function was assessed by INF-gamma ELISPOT assay. Frequencies of EBV-specific CD8 cells tended to be greater in SLE subjects than in healthy control subjects (p=0.07). While over 10% of EBV-specific CD8 cells were capable of producing IFN-gamma in four out of five healthy control subjects, such proportions of EBV-specific CD8 cells capable of IFN-gamma production were observed in only one out of six SLE subjects (p=0.04). In contrast, viral peptide pool-specific and mitogen-induced IFN-gamma-producing T cell function was intact in SLE subjects. Phenotypic analysis revealed EBV-specific CD8 cells to be in an early to intermediate differentiation and resting memory state in both groups. While EBV-specific CD8 cells are similar in phenotype, their frequency tends to be increased, and function appears to be decreased in SLE. Therefore, an impaired EBV-specific CD8 immune response may exist in SLE, potentially contributing to disease pathogenesis.

An altered immune response to Epstein-Barr nuclear antigen 1 in pediatric systemic lupus erythematosus

OBJECTIVE

New examples support the concept that host immune responses to pathogenic organisms can act as the nidus for autoimmunity. Two such examples implicate the Epstein-Barr virus (EBV) in systemic lupus erythematosus (SLE), i.e., data consistent with SLE anti-Sm and anti-60-kd Ro autoantibodies emerging from distinct humoral immune responses to Epstein-Barr nuclear antigen 1 (EBNA-1). We undertook this study to further test whether the humoral immune response to EBNA-1 is a risk factor for pediatric SLE.

METHODS

Sera from pediatric lupus patients and healthy matched controls were tested for anti-EBNA-1 by Western blotting and enzyme-linked immunosorbent assay (ELISA). To define the fine specificity of their anti-EBNA-1 humoral immune response, fragments of EBNA-1 and the maximally overlapping unique octapeptides of EBNA-1 were tested by modified ELISAs.

RESULTS

All 36 pediatric SLE patient sera tested recognized EBNA-1, while sera from only 25 of 36 matched EBV-positive controls targeted EBNA-1 (P < 0.005). Epitope mapping revealed that the humoral anti-EBNA-1 response in pediatric SLE was distinct from and less restricted than that in matched normal individuals. Meanwhile, no significant differences between SLE patient sera and control sera were observed in the responses to other herpesviruses or in binding to sequential epitopes from cytomegalovirus immediate-early antigen or EBNA-2.

CONCLUSION

Anti-EBNA-1 antibodies are associated with pediatric-onset SLE. Furthermore, an altered humoral immune response to EBNA-1, characteristic of SLE, has been found and may be an important SLE susceptibility factor.

Early events in lupus humoral autoimmunity suggest initiation through molecular mimicry

The origins of autoimmunity in systemic lupus erythematosus (SLE) are thought to involve both genetic and environmental factors. To identify environmental agents that could potentially incite autoimmunity, we have traced the autoantibody response in human SLE back in time, prior to clinical disease onset, and identified the initial autoantigenic epitope for some lupus patients positive for antibodies to 60 kDa Ro. This initial epitope directly cross-reacts with a peptide from the latent viral protein Epstein-Barr virus nuclear antigen-1 (EBNA-1). Animals immunized with either the first epitope of 60 kDa Ro or the cross-reactive EBNA-1 epitope progressively develop autoantibodies binding multiple epitopes of Ro and spliceosomal autoantigens. They eventually acquire clinical symptoms of lupus such as leukopenia, thrombocytopenia and renal dysfunction. These data support the hypothesis that some humoral autoimmunity in human lupus arises through molecular mimicry between EBNA-1 and lupus autoantigens and provide further evidence to suspect an etiologic role for Epstein-Barr virus in SLE.

Alterations in lipid raft composition and dynamics contribute to abnormal T cell responses in systemic lupus erythematosus

In response to appropriate stimulation, T lymphocytes from systemic lupus erythematosus (SLE) patients exhibit increased and faster intracellular tyrosine phosphorylation and free calcium responses. We have explored whether the composition and dynamics of lipid rafts are responsible for the abnormal T cell responses in SLE. SLE T cells generate and possess higher amounts of ganglioside-containing lipid rafts and, unlike normal T cells, SLE T cell lipid rafts include FcRgamma and activated Syk kinase. IgM anti-CD3 Ab-mediated capping of TCR complexes occurs more rapidly in SLE T cells and concomitant with dramatic acceleration of actin polymerization kinetics. The significance of these findings is evident from the observation that cross-linking of lipid rafts evokes earlier and higher calcium responses in SLE T cells. Thus, we propose that alterations in the lipid raft signaling machinery represent an important mechanism that is responsible for the heightened and accelerated T cell responses in SLE.