Anti‐dsDNA antibodies as a classification criterion and a diagnostic marker for systemic lupus erythematosus: critical remarks

Antibodies to mammalian dsDNA have, for decades, been linked to systemic lupus erythematosus (SLE) and particularly to its most serious complication, lupus nephritis. This canonical view derives from studies on its strong association with disease. The dogma was particularly settled when the antibody was included in the classification criteria for SLE that developed during the 1970s, most prominently in the 1982 American College of Rheumatology (ACR), and recently in The Systemic Lupus International Collaborating Clinics (SLICC) classification criteria. There are several problems to be discussed before the anti‐dsDNA antibody can be accepted without further distinction as a criterion to classify SLE. Old and contemporary knowledge make it clear that an anti‐dsDNA antibody is not a unifying term. It embraces antibodies with a wide spectrum of fine molecular specificities, antibodies that are produced transiently in context of infections and persistently in the context of true autoimmunity, and also includes anti‐dsDNA antibodies that have the potential to bind chromatin (accessible DNA structures) and not (specificity for DNA structures that are embedded in chromatin and therefore unaccessible for the antibodies). This critical review summarizes this knowledge and questions whether or not an anti‐dsDNA antibody, as simply that, can be used to classify SLE.     

Cytokines in immune‐mediated inflammatory myopathies: cellular sources,multiple actions and therapeutic implications

The idiopathic inflammatory myopathies are a heterogeneous group of disorders characterised by diffuse muscle weakness and inflammation. A common immunopathogenic mechanism is the cytokine‐driven infiltration of immune cells into the muscle tissue. Recent studies have further dissected the inflammatory cell types and associated cytokines involved in the immune‐mediated myopathies and other chronic inflammatory and autoimmune disorders. In this review we outline the current knowledge of cytokine expression profiles and cellular sources in the major forms of inflammatory myopathy and detail the known mechanistic functions of these cytokines in the context of inflammatory myositis. Furthermore, we discuss how the application of this knowledge may lead to new therapeutic strategies for the treatment of the inflammatory myopathies, in particular for cases resistant to conventional forms of therapy.     

Autoimmune,rheumatic, chronic inflammatory diseases: Neutrophil extracellular traps on parade

Abstract

Rheumatic diseases are a group of inflammatory conditions that affect joints and connective tissues and are often accompanied by pain and restriction of motility. In many of these diseases, autoantibodies develop that react with molecules/structures commonly found hidden in neutrophils. Neutrophil extracellular trap (NET) formation and release is considered a defense mechanism against pathogens or endogenous danger signals and it has been associated with initial inflammatory responses. NETs are also endowed with an important resolution potential based on its intrinsic enzymatic activity, but in the case they are not timely removed from the crime scene they might modulate subsequent immune responses and contribute to the pathogenesis of chronic inflammatory diseases. In this review, we will summarize the actual knowledge about the multifaceted roles of NETs in the etiology and pathogenesis of rheumatic autoimmune diseases.     

Serum thymosin α 1 levels in patients with chronic inflammatory autoimmune diseases

Thymosin alpha 1 (Tα1) is a powerful modulator of immunity and inflammation. Despite years of studies, there are a few reports evaluating serum Tα1 in health and disease. We studied a cohort of healthy individuals in comparison with patients affected by chronic inflammatory autoimmune diseases. Sera from 120 blood donors (healthy controls, HC), 120 patients with psoriatic arthritis (PsA), 40 with rheumatoid arthritis (RA) and 40 with systemic lupus erythematosus (SLE), attending the Transfusion Medicine or the Rheumatology Clinic at the Policlinico Tor Vergata, Rome, Italy, were tested for Tα1 content by means of a commercial enzyme‐linked immunosorbent assay (ELISA) kit. Data were analysed in relation to demographic and clinical characteristics of patients and controls. A gender difference was found in the HC group, where females had lower serum Tα1 levels than males (P < 0·0001). Patients had lower serum Tα1 levels than HC (P < 0·0001), the lowest were observed in PsA group (P < 0·0001 versus all the other groups). Among all patients, those who at the time of blood collection were taking disease‐modifying anti‐rheumatic drugs (DMARD) plus steroids had significantly higher Tα1 levels than those taking DMARD alone (P = 0·044) or no treatment (P < 0·0001), but not of those taking steroids alone (P = 0·280). However, whichever type of treatment was taken by the patients, serum Tα1 was still significantly lower than in HC and there was no treatment‐related difference in PsA group. Further prospective studies are necessary to confirm and deepen these observations. They might improve our understanding on the regulatory role of Tα1 in health and disease and increase our knowledge of the pathogenesis of chronic inflammatory autoimmune diseases.     

Carbonic anhydrase III: A new target for autoantibodies in autoimmune diseases

The objective of this study was to identify new autoantibodies that could be useful for the diagnosis of rheumatoid arthritis (RA) using immunoblotting on synovial membrane proteins which represent the best source of candidate RA autoantigens. A new target protein with a molecular weight of 26 kDa was found to be recognized by autoantibodies in RA sera and was identified using MALDI-TOF mass spectrometry and second-dimension electrophoresis as carbonic anhydrase III (CAIII). Three similar protein spots at 26 kDa were recognized by both human sera and monoclonal antibody (mAb) directed against CAIII on immunoblotting using the human recombinant CAIII. Interestingly, CAIII expression within the synovial membrane was not observed in non-RA patients and was differentially expressed among RA patients. The sensitivity of these new autoantibodies for RA, using an immunoenzymatic technique, was 17%. Specificity was high when comparing non-autoimmune diseases (100%), while it was found to be weak (67%) when comparing some other autoimmune diseases, and particularly systemic lupus erythematosus (SLE). In conclusion, this study demonstrates that these new autoantibodies against CAIII are not restricted to RA. However the expression of CAIII in the synovial membrane of RA warrants further investigation of the pathophysiological relevance of this finding.     

Altered metabolic pathways regulate synovial inflammation in rheumatoid arthritis

Rheumatoid arthritis is characterized by synovial proliferation, neovascularization and leucocyte extravasation leading to joint destruction and functional disability. The blood vessels in the inflamed synovium are highly dysregulated, resulting in poor delivery of oxygen; this, along with the increased metabolic demand of infiltrating immune cells and inflamed resident cells, results in the lack of key nutrients at the site of inflammation. In these adverse conditions synovial cells must adapt to generate sufficient energy to support their proliferation and activation status, and thus switch their cell metabolism from a resting regulatory state to a highly metabolically active state. This alters redox-sensitive signalling pathways and also results in the accumulation of metabolic intermediates which, in turn, can act as signalling molecules that further exacerbate the inflammatory response. The RA synovium is a multi-cellular tissue, and while many cell types interact to promote the inflammatory response, their metabolic requirements differ. Thus, understanding the complex interplay between hypoxia-induced signalling pathways, metabolic pathways and the inflammatory response will provide better insight into the underlying mechanisms of disease pathogenesis.     

Association of class II HLA alleles with susceptibility to develop immune-mediated diseases in Paraguayan patients

Genetic and nongenetic factors are involved in the pathogenesis of immune-mediated inflammatory diseases (IMIDs). The best-known genetic factor for susceptibility to IMIDs is the human leukocyte antigen (HLA). The aim of the present study was to evaluate the association of HLA class II genes with the risk of systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), and systemic sclerosis (SSc) in the Paraguayan population. We included 254 patients with IMIDs (101 SLE, 103 RA, and 50 SSc) and 50 healthy controls. The haplotypes of five genes corresponding to HLA class II genes and their relationship to the IMIDs studied were determined. Note that 84.6% were women, with a mean age of 43.4 ± 14 years. Among the associated HLA alleles, we found the previously identified risk factors in other populations like HLA-DRB1*03:01 and HLA-DRB1*14:02 for RA, as well as new ones not previously identified, such as DPA1*02:01 for SLE and, DB1*02:01 for RA and SSc. In the genetic association analysis, already known associations have been replicated, and unpublished associations have been identified in Paraguayan patients with IMIDs. This is the first genetic association study in Paraguayan patients with IMIDs.     

Autoreactive B‐lymphocytes in SLE and RA patients: Isolation and characterisation using extractable nuclear and citrullinated antigens bound to immunobeads

Systemic lupus erythematosus and rheumatoid arthritis are autoimmune diseases characterised by B‐cell hyperactivation and production of autoantibodies (AutoAbs) against various self‐antigens, including extractable nuclear antigens and citrullinated peptides. Therefore, B lymphocytes and antibody‐secreting cells are considered relevant targets for therapies. However, isolation and characterisation of auto‐reactive specific B lymphocytes are limited, primarily due to technical issues. In this work, we purified extractable nuclear antigen‐specific and citrullinated peptide‐specific auto‐reactive B lymphocytes by magnetic selection with ENA‐ and citrullinated peptide‐bound immunobeads. We obtained blood auto‐reactive B lymphocytes from most patients. Their nature was primarily naïve B cells, some of them in an active status, with low levels of somatic hypermutations in the immunoglobulin heavy‐chain variable regions. Their presence correlated with serum levels of autoAb. Auto‐reactive B lymphocytes were able to differentiate into auto‐reactive antibody‐secreting cells under conditions of stimulation. In addition, based on the presence of circulating auto‐reactive B cells and/or antibody‐secreting cells, four different profiles were described in lupus patients. Thus, tracking auto‐reactive B cells and/or antibody‐secreting cells in patient blood could represent a biomarker for deciding whether to use therapies blocking either B cells, plasma cells or both, as well as a new tool for monitoring minimal residual autoimmune disease in patients.     

Driving chronicity in rheumatoid arthritis: perpetuating role of myeloid cells

Acute inflammation is a complex and tightly regulated homeostatic process that includes leucocyte migration from the vasculature into tissues to eliminate the pathogen/injury, followed by a pro‐resolving response promoting tissue repair. However, if inflammation is uncontrolled as in chronic diseases such as rheumatoid arthritis (RA), it leads to tissue damage and disability. Synovial tissue inflammation in RA patients is maintained by sustained activation of multiple inflammatory positive‐feedback regulatory pathways in a variety of cells, including myeloid cells. In this review, we will highlight recent evidence uncovering biological mechanisms contributing to the aberrant activation of myeloid cells that contributes to perpetuation of inflammation in RA, and discuss emerging data on anti‐inflammatory mediators contributing to sustained remission that may inform a novel category of therapeutic targets.     

Interleukin‐17A: a unique pathway in immune‐mediated diseases: psoriasis,psoriatic arthritis and rheumatoid arthritis

Experimental evidence points to the importance of the cytokine interleukin‐17A (IL‐17A) in the pathogenesis of several immunoinflammatory diseases including psoriasis, psoriatic arthritis and rheumatoid arthritis. Although a principal effector of T helper type 17 cells, IL‐17A is produced by many other cell types including CD8⁺ T cells and γδ T cells, and is found at high levels associated with mast cells and neutrophils at sites of skin and joint disease in humans. IL‐17A up‐regulates expression of numerous inflammation‐related genes in target cells such as keratinocytes and fibroblasts, leading to increased production of chemokines, cytokines, antimicrobial peptides and other mediators that contribute to clinical disease features. Importantly, IL‐17A must be considered within the context of the local microenvironment, because it acts synergistically or additively with other pro‐inflammatory cytokines, including tumour necrosis factor. Several direct IL‐17A inhibitors have shown promising activity in proof of concept and phase 2 clinical studies, thereby providing confirmation of experimental data supporting IL‐17A in disease pathogenesis, although levels of response are not predicted by pre‐clinical findings. IL‐17A inhibitors produced rapid down‐regulation of the psoriasis gene signature and high clinical response rates in patients with moderate‐to‐severe plaque psoriasis, consistent with an important role for IL‐17A in psoriasis pathogenesis. Clinical response rates with IL‐17A inhibitors in psoriatic arthritis and rheumatoid arthritis, however, were improved to a lesser degree compared with placebo, suggesting that IL‐17A is either important in a subset of patients or plays a relatively minor role in inflammatory joint disease. Ongoing phase 3 clinical trials should provide further information on the role of IL‐17A in these diseases.     

Immunopathogenesis of systemic lupus erythematosus and rheumatoid arthritis: the role of aberrant expression of non‐coding RNAs in T cells

Non‐coding RNAs (ncRNAs), including microRNAs (miRNAs) and long non‐coding RNAs (lncRNAs), are RNA molecules that do not translate into protein. Both miRNAs and lncRNAs are known to regulate gene expression and to play an essential role in T cell differentiation and function. Both systemic lupus erythematosus (SLE), a prototypic systemic autoimmune disease, and rheumatoid arthritis (RA), a representative disease of inflammatory arthritis, are characterized by a complex dysfunction in the innate and adaptive immunity. T cells play a central role in cell‐mediated immune response and multiple defects in T cells from patients with SLE and RA have been observed. Abnormality in T cell signalling, cytokine and chemokine production, T cell activation and apoptosis, T cell differentiation and DNA methylation that are associated closely with the aberrant expression of a number of miRNAs and lncRNAs have been implicated in the immunopathogenesis of SLE and RA. This review aims to provide an overview of the current state of research on the abnormal expression of miRNAs and lncRNAs in T cells and their roles in the immunopathogenesis of SLE and RA. In addition, by comparing the differences in aberrant expression of miRNAs and lncRNAs in T cells between patients with SLE and RA, controversial areas are highlighted that warrant further investigation.     

Recent advances of exosomes in immune modulation and autoimmune diseases

Exosomes are small membrane-bound vesicles (30-100?nm) that are secreted by different types of cells and they have been well documented to resemble saucers or flattened spheres under the electron microscope. Recently, evidence indicates that exosomes play important roles in the immune modulation and are associated with the immune pathogenesis of autoimmune diseases, including rheumatoid arthritis (RA), Sjogren’s syndrome (SS) and systemic lupus erythematosus (SLE). In this review, we will summarize current research advances of exosomes in immunoregulation, pathogenesis, diagnosis and therapeutics of autoimmune diseases.     

Quantitation and antigenic characterization of bound C3 of circulating immune complexes in systemic lupus erythematosus,rheumatoid arthritis,and primary biliary cirrhosis

In recent years defective function of the complement-mediated clearance of immune complexes (IC) has been reported in patients with immune complex disease. The defect has been found at different levels in the clearance system. An important event in this sequential system is the binding of C3-coated particles to C3 receptors on erythrocytes and phagocytes. This study focuses on immunochemical properties of IC-bound C3 that reflect the functional state of the molecule. Sera from patients with primary biliary cirrhosis (PBC), rhematoid arthritis (RA), and systemic lupus erythematosus (SLE) and from normal subjects were analyzed for their level of C3 precipitable in 2.7% (w/v) polyethylene glycol (PEG). The mean levels for the patient categories were significantly higher than that for the normal subjects. The immunochemical study revealed several differences among the different forms of PEG-precipitable C3. All forms expressed C3(D) antigens which are expressed by immune complex-associated and denatured forms but not by soluble physiological forms of C3. The expression of these antigens was proportionately lower for the complex-associated C3 of PBC compared to that of RA and SLE. Furthermore, employing monoclonal anti-C3(D) antibodies against the C3c and the C3d domain, distinct differences could be detected among all forms of PEG-precipitable C3. Sera from RA and SLE, in particular, contained PEG-precipitable C3 that exhibited distinctive immunochemical features with respect to these epitopes.     

Increased serum levels of soluble interleukin-2 receptor in patients with systemic lupus erythematosus and rheumatoid arthritis

In this study we investigated the serum levels of a released soluble form of the interleukin-2 receptor (sIL-2R) in 42 patients with rheumatoid arthritis and in 12 cases of systemic lupus erythematosus. Data were evaluated in relationship to the clinical phase and compared with those observed in normal controls (N=56) and in osteoarthritis (N = 7). Increased levels were observed in both rheumatoid arthritis (mean ± SE, 604±49 U/ml) and systemic lupus erythematosus (1438±481 U/ml). These values were significantly higher than in control (256±15 U/ml;P<0.001) and in osteoarthritis (298±33 U/ml;P<0.001) groups. In addition, the highest values were associated with the active phases of both rheumatoid arthritis (active vs inactive, 771±78 vs 451±39 U/ml;P<0.001) and systemic lupus erythematosus (active vs inactive, 2108±489 vs 499±75 U/ml;P<0.001). Our findings suggest that the detection of sIL-2R in rheumatoid arthritis and in systemic lupus erythematosus may represent a good marker of disease activity, which indirectly indicates the ongoing activation and/or proliferation of immunoreactive cells which are involved in the pathogenetic events of these autoimmune conditions.     

血清IV型胶原和层粘连蛋白测定在结缔组织病中的意义

目的 探讨血清Ⅳ型胶原（ＩＶ．Ｃ）和层粘连蛋白（ＬＮ）在类风湿关节炎（ＰＡ）、系统性红斑狼疮（ＳＬＥ）和其它结缔组织病（ＣＴＤ）患者中的意义。方法 采用放射免疫法（ＰＩＡ）对３６例ＲＡ、３４例ＳＬＥ和１７例其它ＣＴＤ患者以及６３例正常人的血清ＩＶ．Ｃ和ＬＮ含量进行了测量。结果 各组患者血清ＩＶ．Ｃ和ＬＮ含量均较对照组明显升高（Ｐ〈０．０１～０．０００１）,且ＳＬＥ组血清ＬＮ水平明显提高ＲＡ组（Ｐ〈     

Gene expression profiles of systemic lupus erythematosus and rheumatoid arthritis

Gene expression profiling using microarray technology is being employed to define specific molecular mediators and pathways involved in immunobiology, to understand the intricate interplay of genes participating in the pathogenesis, and to develop biomarkers of disease activity in both systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). This review summarizes the latest information on the pathogenesis of SLE and RA and describes the utilization of microarray technology in these systemic autoimmune diseases.     

Detection of a circulating form of vascular cell adhesion molecule-1: raised levels in rheumatoid arthritis and systemic lupus erythematosus.

We have developed a panel of MoAbs against four separate but overlapping epitopes on endothelial cell (EC) vascular cell adhesion molecule-1 (VCAM-1). Two of the MoAbs (1G11 and 1E5) inhibited T cell adhesion to tumour necrosis factor (TNF)-activated EC, whilst two MoAbs (1.4C3 and 6D9) did not. Using these MoAbs we have identified a circulating form of VCAM-1 (cVCAM-1) which has identical epitope distribution to the EC form, and which is able to support the adhesion of the human lymphoblastoid cell line Jurkat J6 by a VLA-4- and VCAM-1-dependent mechanism when immobilized from plasma. cVCAM-1 isolated by immunoaffinity and size-exclusion chromatographies was shown by SDS-PAGE to have an apparent mol. wt of 85-90 kD. Levels of cVCAM-1 were significantly raised (P < 0.001) in rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) compared with normal individuals. It is possible that cVCAM-1 may be a useful plasma marker for the diagnosis and management of patients with inflammatory diseases. Furthermore, detection of elevated cVCAM-1 levels may act as a guide to the importance of VCAM-1-dependent cell adhesion in different pathological settings.     

Selfie: Autoimmunity,boon or bane

The immune system provides protection to tissues damaged by infectious microrganisms or physical damage. In autoimmune diseases, the immune system recognizes and attacks its own tissues, i.e., self-destruction. Various agents such as genetic factors and environmental triggers are thought to play a major role in the development of autoimmune diseases. A common feature of all autoimmune diseases is the presence of autoantibodies and inflammation, including mononuclear phagocytes, autoreactive T lymphocytes, and autoantibody producing B cells (plasma cells). It has long been known that B cells produce autoantibodies and, thereby, contribute to the pathogenesis of many autoimmune diseases. Autoimmune diseases can be classified as organ-specific or non-organ specific depending on whether the autoimmune response is directed against a particular tissue or against widespread antigens as in chronic inflammatory autoimmune diseases such as systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). Both SLE and RA are characterized by the presence of autoantibodies which play a major role in their etiopathogenesis. SLE is characterized by circulating antibodies and immune complex deposition that can trigger an inflammatory damage in organs. RA is a progressive inflammatory disease in which T cells, B cells, and pro-inflammatory cytokines play a key role in its pathophysiology.