CD4~+CD25~+Treg细胞在类风湿关节炎中的研究进展

调节性T细胞(Tregs)是近年来发现的一群具有免疫调节作用的CD4+T细胞亚群,如Th3、Tr1细胞等。因其能够产生多种具有免疫抑制作用的细胞因子而发挥其免疫负调节作用,不但在维持机体自身耐受方面发挥重要作用,在预防自身免疫性疾病方面也占据重要位置。其中CD4+CD25+Treg因其具有独特的作用方式及功能特征,而被学者广泛关注。近年来,关于CD4+CD25+Treg在类风湿关节炎(rheumatoid arthritis,RA)发病机制中的作用以及在RA治疗方面的应用也越来越受到人们的关注,认为其数目减少或功能失调与RA发病密切相关。RA是一种以关节破坏为主要表现的慢性炎症性疾病,病理早期主要表现为毛细血管生成,滑膜增生,后期主要表现为炎性细胞浸润,血管翳形成,并出现关节软骨以及骨的破坏,最终导致关节畸形及功能障碍。本文现将CD4+CD25+Treg与RA的研究进展做一综述。     

Deficient CD4+CD25high T regulatory cell function in patients with active systemic lupus erythematosus

CD4(+)CD25(+) T regulatory cells (Tregs) play an essential role in maintaining immunologic homeostasis and preventing autoimmunity. Systemic lupus erythematosus (SLE) is a systemic autoimmune disease characterized by a loss of tolerance to nuclear components. We hypothesized that altered function of CD4(+)CD25(high) Tregs might play a role in the breakdown of immunologic self-tolerance in patients with SLE. In this study, we report a significant decrease in the suppressive function of CD4(+)CD25(high) Tregs from peripheral blood of patients with active SLE as compared with normal donors and patients with inactive SLE. Notably, CD4(+)CD25(high) Tregs isolated from patients with active SLE expressed reduced levels of FoxP3 mRNA and protein and poorly suppressed the proliferation and cytokine secretion of CD4(+) effector T cells in vitro. In contrast, the expression of FoxP3 mRNA and protein and in vitro suppression of the proliferation of CD4(+) effector T cells by Tregs isolated from inactive SLE patients, was comparable to that of normal individuals. In vitro activation of CD4(+)CD25(high) Tregs from patients with active SLE increased FoxP3 mRNA and protein expression and restored their suppressive function. These data are the first to demonstrate a reversible defect in CD4(+)CD25(high) Treg function in patients with active SLE, and suggest that strategies to enhance the function of these cells might benefit patients with this autoimmune disease.     

Detecting shared pathways linked to rheumatoid arthritis with other autoimmune diseases in a in silico analysis

Pathway-based analysis approach has exploded in use during the last several years. It is successful in recognizing additional biological insight of disease and finding groupings of risk genes that represent disease developing processes. Therefore, shared pathways, with pleiotropic effects, are important for understanding similar pathogenesis and indicating the common genetic origin of certain diseases. Here, we present a pathway analysis to reveal the potential disease associations between RA and three potential RA-related autoimmune diseases: psoriasis, diabetes mellitus, type 1 (T1D) and systemic lupus erythematosus (SLE). First, a comprehensive knowledge mining of public databases is performed to discover risk genes associated with RA, T1D, SLE and psoriasis; then by enrichment test of these genes, disease-related risk pathways are detected to recognize the pathways common for RA and three other diseases. Finally, the underlying disease associations are evaluated with the association rules mining method. In total, we identify multiple RA risk pathways with significant pleiotropic effects, the most unsurprising of which are the immunology related pathways. Meanwhile for the first time we highlight the involvement of the viral myocarditis pathway related to cardiovascular disease (CVD) in autoimmune diseases such as RA, psoriasis, T1D and SLE. Further Association rule mining results validate the strong association between RA and T1D and RA and SLE. It is clear that pleiotropy is a common property of pathways associated with disease traits. We provide novel pathway associations among RA and three autoimmune diseases. These results ascertain that there are shared genetic risk profiles that predispose individuals to autoimmune diseases.     

Clinical and immunological aspects of autoantibodies to RA33/hnRNP-A/B proteins — A link between RA,SLE and MCTD

Heterogeneous nuclear ribonucleoprotein (hnRNP) complexes are major constituents of the spliceosome. They are composed of approximately 30 different proteins which can bind to nascent pre-mRNA. Among these, the hnRNP-A/B proteins form a subgroup of highly related proteins consisting of two adjacent RNA binding domains (RBD) within the N-terminal parts, whereas the C-terminal halves contain almost 50% glycine residues. These proteins, in particular A2/RA33, are targeted by autoantibodies from patients with rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), and mixed connective tissue disease (MCTD). In SLE anti-hnRNP antibodies frequently occur together with antibodies to U1 small nuclear RNP (U1-snRNP) and Sm, other proteins of the spliceosome. Preliminary epitope mapping studies have revealed major antibody binding sites in the RNA binding regions for all three diseases. Nevertheless, there is some indication of disease specific epitope recognition. Studies in animal models have demonstrated anti-RA33/hnRNP-A/B antibodies in lupus-prone mouse strains.Thus, autoantibodies to the spliceosomal hnRNP-A/B proteins are a common feature of RA, SLE, and MCTD. However, these diseases differ in their reactivities to other spliceosomal proteins, especially anti-U1 snRNP and Sm. Therefore, anti-RA33/hnRNP-A/B autoantibodies are not only valuable diagnostic markers but may also allow additional insights into the pathogenesis of rheumatic autoimmune diseases.Abbreviations AS ankylosing spondylitis - hnRNP heterogeneous nuclear ribonucleoprotein - MCTD mixed connective tissue disease - PSA psoriatic arthropathy - RA rheumatoid arthritis - RBD RNA binding domain - SLE systemic lupus erythematosus - snRNP small nuclear ribonucleoprotein     

B-cell depletion for rheumatic diseases: where are we?

Immune system dysfunction is common to rheumatic disorders, with rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) being classic examples. Altered development and function of B cells may play a prominent role. B-cell abnormalities also occur in other rheumatic diseases, eg, Sjogren's syndrome, Behcet's disease, antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis, and dermatomyositis. Hence, B-cell depletion has been investigated as a therapeutic option. Clinical trials in RA and SLE have shown that rituximab, an anti-CD20 monoclonal antibody, can profoundly reduce disease activity and is generally well tolerated. Reports of rituximab treatment for ANCA-associated vasculitis and dermatomyositis are also promising. These encouraging results validate the strategy of B-cell depletion in various rheumatic diseases. B-cell depletion with rituximab is under study in larger clinical trials for the purposes of regulatory approval to define more closely its place in RA and SLE treatment paradigms, and smaller clinical trials are ongoing or planned in associated inflammatory diseases.     

Type 1 diabetes-associated IL2RA variation lowers IL-2 signaling and contributes to diminished CD4+CD25+ regulatory T cell function

Numerous reports have demonstrated that CD4(+)CD25(+) regulatory T cells (Tregs) from individuals with a range of human autoimmune diseases, including type 1 diabetes, are deficient in their ability to control autologous proinflammatory responses when compared with nondiseased, control individuals. Treg dysfunction could be a primary, causal event or may result from perturbations in the immune system during disease development. Polymorphisms in genes associated with Treg function, such as IL2RA, confer a higher risk of autoimmune disease. Although this suggests a primary role for defective Tregs in autoimmunity, a link between IL2RA gene polymorphisms and Treg function has not been examined. We addressed this by examining the impact of an IL2RA haplotype associated with type 1 diabetes on Treg fitness and suppressive function. Studies were conducted using healthy human subjects to avoid any confounding effects of disease. We demonstrated that the presence of an autoimmune disease-associated IL2RA haplotype correlates with diminished IL-2 responsiveness in Ag-experienced CD4(+) T cells, as measured by phosphorylation of STAT5a, and is associated with lower levels of FOXP3 expression by Tregs and a reduction in their ability to suppress proliferation of autologous effector T cells. These data offer a rationale that contributes to the molecular and cellular mechanisms through which polymorphisms in the IL-2RA gene affect immune regulation, and consequently upon susceptibility to autoimmune and inflammatory diseases.     

Regulatory T cells as a potent target for controlling bone loss

Metabolic bone diseases, such as rheumatoid arthritis (RA) and osteoporosis, affect hundreds and millions of people worldwide leading causes of long-term pain and disability. Effective clinical treatment for bone destruction in bone diseases is lacking because the knowledge about molecular mechanisms leading to bone destruction are incompletely understood. Recently, it has been confirmed that regulatory T cells (Tregs) play a crucial role in suppressing the immune response in the pathogenesis of various autoimmune diseases. In vitro, Tregs directly inhibit osteoclasts and differentiation and function. In mice, the injection of Tregs into the TNF transgenic results in enhanced systemic bone density. In addition, it has been shown that increase of Tregs numbers by overexpressing the FoxP3 is effective in the prevention of local and systemic bone destruction. In vivo treatment with anti-CD28 superagonist antibody leading to a stronger increase in Tregs numbers protect against TNF-a-induced bone loss in TNF-transgenic mice. In agreement, Tregs can control ovariectomy-induced bone loss in FoxP3-transgenic mice. In this paper, we will briefly discuss the biological features of Tregs and summarize recent advances on the role of Tregs in the pathogenesis and treatment of bone loss in metabolic bone diseases.     

Global natural regulatory T cell depletion in active systemic lupus erythematosus

The immune defect that could account for the multisystemic involvement that characterizes systemic lupus erythematosus (SLE) remains unknown. We hypothesized that iterative disease flares correspond to a recurrent defect in the peripheral immune suppression exerted by naturally occurring T regulatory cells (Tregs). Surprisingly, Tregs isolated from lupus patients show the same phenotypic and functional characteristics as corresponding cells found in healthy controls. A decrease in the proportion of circulating Tregs among other CD4+ T cells is nevertheless evidenced in active patients when this group is compared with healthy controls (0.57 +/- 0.24%, n = 45 vs 1.29 +/- 0.38%, n = 82, p < 0.0001) or with inactive patients (1.22 +/- 0.67%, n = 62, p < 0.0001). In contrast, the proportion of Tregs in other systemic autoimmune diseases such as primary Sj?gren syndrome and inflammatory myopathy does not significantly differ from controls' values (1.15 +/- 0.46%, n = 21, p = 0.09 and 1.16 +/- 0.44%, n = 16, p = 0.43, respectively). Lupus Tregs do not accumulate in either the lymph nodes or the diseased kidneys and are not killed by a circulating soluble factor, but demonstrate in vitro a heightened sensitivity to Fas-induced apoptosis. Finally, we show that the extent of Treg depletion correlates with the clinical severity of the flare. SLE flares are therefore associated with a global Treg depletion and not with a phenomenon of tissue redistribution. In summary, we suggest that the physiopathology of SLE could be tied to a defect in the homeostatic control of the Treg subpopulation.     

Reactive oxygen species, lipid peroxides and essential fatty acids in patients with rheumatoid arthritis and systemic lupus erythematosus

We studied free radical generation, lipid peroxidation and the levels of essential fatty acids and of their metabolites in patients with rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). Both superoxide and hydrogen peroxide generation by peripheral leukocytes but not malondialdehyde levels, as measured by thiobarbituric acid assay, were found to be significantly enhanced both in RA and SLE. Fatty acid analysis of the plasma PL fraction revealed that both LA and ALA metabolites are significantly decreased in RA and SLE compared to controls. These results suggest that essential fatty acid metabolism is altered in RA and SLE.     

Central role of nitric oxide in the pathogenesis of rheumatoid arthritis and sysemic lupus erythematosus

Nitric oxide (NO) has been shown to regulate T cell functions under physiological conditions, but overproduction of NO may contribute to T lymphocyte dysfunction. NO-dependent tissue injury has been implicated in a variety of rheumatic diseases, including systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). Several studies reported increased endogenous NO synthesis in both SLE and RA, and recent evidence suggests that NO contributes to T cell dysfunction in both autoimmune diseases. The depletion of intracellular glutathione may be a key factor predisposing patients with SLE to mitochondrial dysfunction, characterized by mitochondrial hyperpolarization, ATP depletion and predisposition to death by necrosis. Thus, changes in glutathione metabolism may influence the effect of increased NO production in the pathogenesis of autoimmunity.     

CD4+CD25+/highCD127low/- regulatory T cells are enriched in rheumatoid arthritis and osteoarthritis joints—analysis of frequency and phenotype in synovial membrane,synovial fluid and peripheral blood

Introduction

CD4⁺CD25^+/highCD127^low/- regulatory T cells (Tregs) play a crucial role in maintaining peripheral tolerance. Data about the frequency of Tregs in rheumatoid arthritis (RA) are contradictory and based on the analysis of peripheral blood (PB) and synovial fluid (SF). Because Tregs exert their anti-inflammatory activity in a contact-dependent manner, the analysis of synovial membrane (SM) is crucial. Published reports regarding this matter are lacking, so we investigated the distribution and phenotype of Tregs in concurrent samples of SM, SF and PB of RA patients in comparison to those of osteoarthritis (OA) patients.

Methods

Treg frequency in a total of 40 patients (18 RA and 22 OA) matched for age and sex was assessed by flow cytometry. Functional status was assessed by analysis of cell surface markers representative of activation, memory and regulation.

Results

CD4⁺ T cells infiltrate the SM to higher frequencies in RA joints than in OA joints (P = 0.0336). In both groups, Tregs accumulate more within the SF and SM than concurrently in PB (P < 0.0001). Relative Treg frequencies were comparable in all compartments of RA and OA, but Treg concentration was significantly higher in the SM of RA patients (P = 0.025). Both PB and SM Tregs displayed a memory phenotype (CD45RO⁺RA^-), but significantly differed in activation status (CD69 and CD62L) and markers associated with Treg function (CD152, CD154, CD274, CD279 and GITR) with only minor differences between RA and OA.

Conclusions

Treg enrichment into the joint compartment is not specific to inflammatory arthritis, as we found that it was similarly enriched in OA. RA pathophysiology might not be due to a Treg deficiency, because Treg concentration in SM was significantly higher in RA. Synovial Tregs represent a distinct phenotype and are activated effector memory cells (CD62L^-CD69⁺), whereas peripheral Tregs are resting central memory cells (CD62L⁺CD69^-).     

Regulatory T cells and TH1/TH2 cytokines as immunodiagnosis keys in systemic autoimmune diseases

We assessed Helper T-cell involvement and possibilities to quantify the cell-based immune response in systemic autoimmune diseases (SAID) in 14 systemic lupus erythematosus (SLE) and 7 rheumatoid arthritis (RA) patients. The goals of investigation were T-CD4+/T-CD8+ ratio, regulatory T cells (Treg) status and TH1/TH2 serum cytokine profiles (IFN-gamma and IL-2, respectively IL-4 and IL-6). SLE group proved significant decreased average Treg value as compared to RA group and controls and showed significant low Treg incidence (86% patients). The distribution of high T-CD4+/T-CD8+ ratio registered no significant distinction among LES and RA groups. SAID patients presented low serum IFN-gamma (86% RA, 60% SLE), high IL-2 (57% RA) and high IL-6 (53% LES), but no significant IL-4 modification. We conclude that Treg percentage remains the only cellular criterion for SAID immune evaluation. In the same time, different secretion mechanisms seem to be involved in SAID, i.e. TH2 in SLE and TH1 in RA.     

Radiation therapy of spontaneous autoimmunity: a review of mouse models

The classical types of generalized autoimmune disease in man are systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). Several murine strains which develop SLE and sometimes RA-like diseases are now available. They should help in the understanding of the etiopathology of SLE and RA. Basically two main therapeutic strategies which use solely irradiation have been tried; one being sublethal whole-body irradiation (WBI) and the other fractionated total lymphoid irradiation (TLI). Other protocols which combine lethal WBI and stem cell transplantation have often been attempted. It was regularly found that the bone marrow transplant (BMT) dictates the immune status of the recipient. This paper reviews the data published about NZB, NZB/W, BXSB and MRL mice in this context.     

Immunosuppressive therapy influences the accelerated age-dependent T-helper cell differentiation in systemic lupus erythematosus remission patients

Background

CD4⁺ T cells are of great importance in the pathogenesis of systemic lupus erythematosus (SLE), as an imbalance between CD4⁺ regulatory T cells (Tregs) and CD4⁺ responder T cells (Tresps) causes flares of active disease in SLE patients. In this study, we aimed to find the role of aberrant Treg/Tresp cell differentiation for maintaining Treg/Tresp cell balance and Treg functionality.

Methods

To determine differences in the differentiation of Tregs/Tresps we calculated the percentages of CD45RA⁺CD31⁺ recent thymic emigrant (RTE) Tregs/Tresps and CD45RA⁺CD31^? mature naive (MN) Tregs/Tresps, as well as CD45RA^?CD31⁺ and CD45RA^?CD31^? memory Tregs/Tresps (CD31⁺ and CD31^? memory Tregs/Tresps) within the total Treg/Tresp pool of 78 SLE remission patients compared with 94 healthy controls of different ages. The proliferation capacity of each Treg/Tresp subset was determined by staining the cells with anti-Ki67 monoclonal antibodies. Differences in the autologous or allogeneic Treg function between SLE remission patients and healthy controls were determined using suppression assays.

Results

With age, we found an increased differentiation of RTE Tregs via CD31⁺ memory Tregs and of RTE Tresps via MN Tresps into CD31^? memory Tregs/Tresp in healthy volunteers. This opposite differentiation of RTE Tregs and Tresps was associated with an age-dependent increase in the suppressive activity of both naive and memory Tregs. SLE patients showed similar age-dependent Treg cell differentiation. However, in these patients RTE Tresps differentiated increasingly via CD31⁺ memory Tresps, whereby CD31^? memory Tresps arose that were much more difficult to inhibit for Tregs than those that emerged through differentiation via MN Tresps. Consequently, the increase in the suppressive activity of Tregs with age could not be maintained in SLE patients. Testing the Tregs of healthy volunteers and SLE patients with autologous and nonautologous Tresps revealed that the significantly decreased Treg function in SLE patients was not exclusively attributed to an age-dependent diminished sensitivity of the Tresps for Treg suppression. The immunosuppressive therapy reduced the accelerated age-dependent Tresp cell proliferation to normal levels, but simultaneously inhibited Treg cell proliferation below normal levels.

Conclusions

Our data reveal that the currently used immunosuppressive therapy has a favorable effect on the differentiation and proliferation of Tresps but has a rather unfavorable effect on the proliferation of Tregs. Newer substances with more specific effects on the immune system would be desirable.

     

Analysis of families in the multiple autoimmune disease genetics consortium (MADGC) collection: the PTPN22 620W allele associates with multiple autoimmune phenotypes

Autoimmune disorders constitute a diverse group of phenotypes with overlapping features and a tendency toward familial aggregation. It is likely that common underlying genes are involved in these disorders. Until very recently, no specific alleles--aside from a few common human leukocyte antigen class II genes--had been identified that clearly associate with multiple different autoimmune diseases. In this study, we describe a unique collection of 265 multiplex families assembled by the Multiple Autoimmune Disease Genetics Consortium (MADGC). At least two of nine "core" autoimmune diseases are present in each of these families. These core diseases include rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), type 1 diabetes (T1D), multiple sclerosis (MS), autoimmune thyroid disease (Hashimoto thyroiditis or Graves disease), juvenile RA, inflammatory bowel disease (Crohn disease or ulcerative colitis), psoriasis, and primary Sjogren syndrome. We report that a recently described functional single-nucleotide polymorphism (rs2476601, encoding R620W) in the intracellular tyrosine phosphatase (PTPN22) confers risk of four separate autoimmune phenotypes in these families: T1D, RA, SLE, and Hashimoto thyroiditis. MS did not show association with the PTPN22 risk allele. These findings suggest a common underlying etiologic pathway for some, but not all, autoimmune disorders, and they suggest that MS may have a pathogenesis that is distinct from RA, SLE, and T1D. DNA and clinical data for the MADGC families are available to the scientific community; these data will provide a valuable resource for the dissection of the complex genetic factors that underlie the various autoimmune phenotypes.     

Presence of antibodies against cyclic citrullinated peptides in patients with 'rhupus': a cross-sectional study

'Rhupus' is a rare condition sharing features of rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). If rhupus is a distinctive entity, an overlap between RA and SLE or a subset of SLE is currently debated. This study was performed to explore the prevalence of antibodies against cyclic citrullinated peptides (anti-CCP antibodies) in rhupus. Patients meeting American College of Rheumatology criteria for RA, SLE, or both were included. Clinical and radiographic features were recorded and sera were searched for anti-CCP antibodies, rheumatoid factor, antinuclear antibodies, anti-extractable nuclear antigens, and antibodies against double-stranded DNA (anti-dsDNA antibodies). Seven patients for each group were included. Clinical and serological features for RA or SLE were similar between rhupus and RA patients, and between rhupus and SLE patients, respectively. Values for anti-CCP antibodies obtained were significantly (p < 0.05) higher in RA (6/7) and rhupus (4/7) than in SLE patients (0/7) and healthy subjects (0/7). Our data support the possibility that rhupus is an overlap between RA and SLE, because highly specific autoantibodies for RA (anti-CCP) and for SLE (anti-dsDNA and anti-Sm) are detected in coexistence.     

Defective response of CD4(+) T cells to retinoic acid and TGFβ in systemic lupus erythematosus

Introduction  

CD25⁺ FOXP3⁺ CD4⁺ regulatory T cells (Tregs) are induced by transforming growth factor β (TGFβ) and further expanded by retinoic acid (RA). We have previously shown that this process was defective in T cells from lupus-prone mice expressing the novel isoform of the Pbx1 gene, Pbx1-d. This study tested the hypothesis that CD4⁺ T cells from systemic lupus erythematosus (SLE) patients exhibited similar defects in Treg induction in response to TGFβ and RA, and that PBX1-d expression is associated with this defect.     

Contrasting effects of TNF and anti-TNF on the activation of effector T cells and regulatory T cells in autoimmunity

Anti-TNF treatment is effective in a majority of rheumatoid arthritis (RA), however, this treatment can unexpectedly trigger the onset or exacerbate multiple sclerosis (MS). Recent progress in cellular immunology research provides a new framework to analyze the possible mechanism underlying these puzzling contradictory effects. The delicate balance of protective CD4(+)FoxP3(+) regulatory T cells (Tregs) and pathogenic CD4(+)FoxP3(-) effector T cells (Teffs) is crucial for the outcome of anti-TNF treatment of autoimmune disease. There is convincing evidence that TNF, in addition to stimulating Teffs, is able to activate and expand Tregs through TNFR2, which is preferentially expressed by Tregs. Therefore, the contrasting effects of TNF on Tregs and Teffs are likely to determine the therapeutic effect of anti-TNF treatment. In this review, we discuss the current understanding of the general effect of TNF on the activation of T cells, and the impact of TNF on the function of Teffs and Tregs. Understanding the differential effects of TNF on Teffs and Tregs is fundamentally required for the design of more effective and safer anti-TNF or anti-TNF receptor(s) therapeutic strategy for autoimmune diseases.