Tissue targeting of anti-RNP autoimmunity: effects of T cells and myeloid dendritic cells in a murine model

Application of principal component analysis and logistic regression model in lupus nephritis patients with clinical hypothyroidism

Background

Previous studies indicate that the prevalence of hypothyroidism is much higher in patients with lupus nephritis (LN) than in the general population, and is associated with LN’s activity. Principal component analysis (PCA) and logistic regression can help determine relevant risk factors and identify LN patients at high risk of hypothyroidism; as such, these tools may prove useful in managing this disease.

Methods

We carried out a cross-sectional study of 143 LN patients diagnosed by renal biopsy, all of whom had been admitted to Xiangya Hospital of Central South University in Changsha, China, between June 2012 and December 2016. The PCA–logistic regression model was used to determine the influential principal components for LN patients who have hypothyroidism.

Results

Our PCA–logistic regression analysis results demonstrated that serum creatinine, blood urea nitrogen, blood uric acid, total protein, albumin, and anti-ribonucleoprotein antibody were important clinical variables for LN patients with hypothyroidism. The area under the curve of this model was 0.855.

Conclusion

The PCA–logistic regression model performed well in identifying important risk factors for certain clinical outcomes, and promoting clinical research on other diseases will be beneficial. Using this model, clinicians can identify at-risk subjects and either implement preventative strategies or manage current treatments.

An Autoimmune Basis for Raynaud's Phenomenon: Murine Model and Human Disease

OBJECTIVE

Raynaud's phenomenon (RP) is common in anti-RNP-positive patients with rheumatic diseases but is not itself known to be caused by autoimmunity. The aim of this study was to assess autoantibodies that could mediate this process.

METHODS

Antibodies derived from patient sera and from murine models of anti-RNP autoimmunity were screened for the ability to induce RP-like tissue ischemia and endothelial cell apoptosis in murine models and in vitro systems.

RESULTS

RNP-positive sera from RP patients and murine sera from RNP-positive B cell adoptive transfer recipients induced RP-like tissue ischemia and endothelial cell apoptosis. Proteomic analysis identified cytokeratin 10 (K10) as a candidate autoantigen in RP. Monoclonal anti-K10 antibodies reproduced patterns of ischemic tissue loss and endothelial cell apoptosis; K10 knockout or depletion of anti-K10 activity in serum was protective. Cold exposure enhanced K10 expression and in vivo tissue loss.

CONCLUSION

Anti-K10 antibodies are sufficient to mediate RP-like ischemia in murine models and are implicated in the pathogenesis of RP in patients with anti-RNP autoimmunity.

The mechanisms and applications of T cell vaccination for autoimmune diseases: a comprehensive review

Autoimmune diseases (ADs) are a spectrum of diseases originating from loss of immunologic self-tolerance and T cell abnormal autoreactivity, causing organ damage and death. However, the pathogenic mechanism of ADs remains unclear. The current treatments of ADs include nonsteroidal anti-inflammatory drugs (NSAIDS), antimalarials, corticosteroids, immunosuppressive drugs, and biological therapies. With the need to prevent side effects resulting from current treatments and acquire better clinical remission, developing a novel pharmaceutical treatment is extremely urgent. The concept of T cell vaccination (TCV) has been raised as the finding that immunization with attenuated autoreactive T cells is capable of inducing T cell-dependent inhibition of autoimmune responses. TCV may act as an approach to control unwanted adaptive immune response through eliminating the autoreactive T cells. Over the past decades, the effect of TCV has been justified in several animal models of autoimmune diseases including experimental autoimmune encephalomyelitis (EAE), murine autoimmune diabetes in nonobese diabetic (NOD) mice, collagen-induced arthritis (CIA), and so on. Meanwhile, clinical trials of TCV have confirmed the safety and efficacy in corresponding autoimmune diseases ranging from multiple sclerosis (MS) to systemic lupus erythematosus (SLE). This review aims to summarize the ongoing experimental and clinical trials and elucidate possible molecule mechanisms of TCV.

Diagnosis and risk stratification in patients with anti-RNP autoimmunity

INTRODUCTION

Anti-RNP autoantibodies occur either in mixed connective tissue disease (MCTD) (with a frequently favorable prognosis), or in systemic lupus erythematosus (SLE) cases with aggressive major organ disease. It is uncertain how to assess for the risk of severe disease in anti-RNP + patients.

METHODS

Following institutional review board-approved protocols, clinical data and blood were collected from patients with known or suspected anti-RNP autoimmunity and normal controls in a cohort study. Samples were screened for parameters of immune activation. Groups were compared based on clinical diagnoses, disease classification criteria, disease activity and specific end-organ clinical manifestations.

RESULTS

Ninety-seven per cent of patients satisfying Alarcon-Segovia MCTD criteria also met Systemic Lupus International Collaborating Clinic (SLICC) SLE criteria, while 47% of the anti-RNP + SLE patients also met MCTD criteria. Among SLICC SLE patients, MCTD criteria were associated with reduced rates of renal disease (odds ratio (OR) 4.3, 95% confidence interval (CI) 1.3-14.0), increased rates of Raynaud's phenomenon (OR 3.5, 95% CI 1.3-9.5) and increased serum B-cell maturation antigen, transmembrane activator and CAML interactor and TNFα levels. Circulating immune markers and markers of type I interferon activation were not effective at distinguishing clinical subgroups.

CONCLUSIONS

Among anti-RNP patients, the question of MCTD versus SLE is not either/or: most MCTD patients also have lupus. MCTD classification criteria (but not a broad set of immune markers) distinguish a subset of SLE patients at reduced risk for renal disease.

Conservation of pathogenic TCR homology across class II restrictions in anti-ribonucleoprotein autoimmunity: extended efficacy of T cell vaccine therapy

T cells have been shown to mediate aspects of anti-ribonucleoprotein (RNP) autoimmunity, and are a potential target of therapy in lupus and related diseases. In this study, we assessed the relevance of a conserved class of anti-RNP T cells to autoimmune disease expression and therapy. Our data show that anti-RNP T cell selection induced a limited set of homologous CDR3 motifs at high frequency. Homologous CDR3 motifs have been reported in other autoimmune diseases. Vaccination with irradiated anti-RNP (but not anti-tetanus toxoid) CD4(+) cells induced remission of anti-RNP-associated nephritis in ≥ 80% of treated mice, even with donor/recipient MHC class II mismatch, and in both induced and spontaneous autoimmunity. Vaccine responder sera inhibited anti-70k T cell proliferation and bound hybridomas expressing the conserved CDR3 motifs. Our data indicate that a limited set of TCR CDR3 motifs may be important for the pathogenesis of anti-RNP lupus and other autoimmune diseases. The ability to target a consistent set of pathogenic T cells between individuals and across class II restrictions may allow for the more practical development of a standardized anti-RNP T cell vaccine preparation useful for multiple patients.

Serum antibodies against the 70k polypeptides of the U1 ribonucleoprotein complex are associated with psychiatric syndromes in systemic lupus erythematosus: a retrospective study

OBJECTIVES

We assessed the association between serum autoantibodies against the 70-kDa polypeptide of the U1-ribonucleoprotein (RNP) complex (U1-70k) and the central nervous system (CNS) syndromes in systemic lupus erythematosus (SLE) patients.

METHODS

We studied 106 hospitalized patients with active SLE, comparing those with (n = 32) and without (n = 74) CNS syndromes. CNS syndromes were further classified into neurologic (n = 21) and psychiatric (n = 15) disorders. Immunoglobulin G (IgG) anti-U1-70k antibodies were measured by enzyme-linked immunosorbent assay (ELISA) using recombinant antigens. IgG antibodies against whole U1-RNP were measured using commercial ELISA kits.

RESULTS

Although there was no significant difference in the levels of serum anti-U1-70k antibodies in SLE patients with or without CNS syndromes (p = 0.83), the levels were significantly elevated in SLE patients compared with patients without psychiatric syndromes (p = 0.030). In contrast, no significant difference was observed in the levels of serum anti-U1-RNP antibodies in SLE patients with or without psychiatric syndromes (p = 0.555).

CONCLUSIONS

These results indicate that serum anti-U1-70k antibodies are associated with psychiatric syndromes in SLE but that they are not associated with CNS syndromes as a whole or with neurologic syndromes. The anti-U1-70k antibodies might be involved in the pathological mechanisms of psychiatric syndromes in SLE.

T cell vaccination therapy in an induced model of anti-RNP autoimmune glomerulonephritis

To establish the relevance of targeting disease-associated T cells in anti-RNP-associated glomerulonephritis, mice developing nephritis following immunization with U1-70-kd small nuclear ribonucleoprotein (snRNP) were treated with a single dose of irradiated antigen-selected T cell vaccine. T cell receptor usage in nephritic kidneys revealed oligoclonal use of T Cell Receptor V Beta (TRBV) genes as previously found in spleens and lungs of immunized mice with pulmonary disease. The CDR3 regions from T cell isolates showed sequence homology to those in humans with anti-RNP autoimmunity. Following T cell vaccination, urinalysis returned to normal in 5/7 treated mice (71% response rate) whereas all mock-treated mice continued to have an active urinary sediment (Fisher's Exact p=0.02). An oligoclonal population of T cells homologous to those identified in humans with anti-RNP autoimmunity is implicated in disease pathogenesis, and T cell vaccination is associated with a high rate of clinical improvement in established nephritis.

Clinical and Serologic Factors Associated with Lupus Pleuritis

Objective.

Pleuritis is a common manifestation and independent predictor of mortality in systemic lupus erythematosus (SLE). We examined the prevalence of pleuritis and factors associated with pleuritis in a multicenter Canadian SLE cohort.

Methods.

We studied consecutive adults satisfying the American College of Rheumatology (ACR) classification criteria for SLE who had a completed Systemic Lupus International Collaborating Clinics/ACR Damage Index (SDI) score, at least 1 evaluable extractable nuclear antigen assay, and either a SLE Disease Activity Index (SLEDAI) or a SLE Activity Measure score. Pleuritis was defined as having pleuritis by satisfying the ACR criteria or the SLEDAI. Factors related to pleuritis were examined using univariate and multivariate logistic regression.

Results.

In our cohort of 876 patients, 91% were women, 65% Caucasian, mean age (± SD) was 46.8 ± 13.5 years, and disease duration at study entry was 12.1 ± 9.9 years; the prevalence of pleuritis was 34% (n = 296). Notably, greater disease duration (p = 0.002), higher SDI score (p ≤ 0.0001), age at SLE diagnosis (p = 0.009), and anti-Sm (p = 0.002) and anti-RNP (p = 0.002) seropositivity were significantly associated with pleuritis. In multivariate analysis with adjustment for disease duration, age at diagnosis, and SDI score, concomitant seropositivity for RNP and Sm were related to a nearly 2-fold greater prevalence of pleuritis (OR 1.98, 95% CI 1.31–2.82).

Conclusion.

Pleuritis occurred in one-third of this Canadian cohort. Concomitant Sm and RNP seropositivity, greater cumulative damage, longer disease duration, and younger age at SLE disease onset were related to a higher rate of SLE pleural disease.

The U1-snRNP complex: structural properties relating to autoimmune pathogenesis in rheumatic diseases

The U1 small nuclear ribonucleoprotein particle (snRNP) is a target of autoreactive B cells and T cells in several rheumatic diseases including systemic lupus erythematosus (SLE) and mixed connective tissue disease (MCTD). We propose that inherent structural properties of this autoantigen complex, including common RNA-binding motifs, B and T-cell epitopes, and a unique stimulatory RNA molecule, underlie its susceptibility as a target of the autoimmune response. Immune mechanisms that may contribute to overall U1-snRNP immunogenicity include epitope spreading through B and T-cell interactions, apoptosis-induced modifications, and toll-like receptor (TLR) activation through stimulation by U1-snRNA. We conclude that understanding the interactions between U1-snRNP and the immune system will provide insights into why certain patients develop anti-U1-snRNP autoimmunity, and more importantly how to effectively target therapies against this autoimmune response.

Endosomal Toll-like receptors in autoimmunity: mechanisms for clinical diversity

The endosomal Toll-like receptors (TLR3, TLR7 and TLR9) have been implicated in the pathogenesis of autoimmune diseases. Their signaling pathways show remarkable similarities and yet the outcomes following activation of each of these TLRs lead to clinically distinct autoimmune disease phenotypes. This review discusses how differences may arise at a molecular and cellular level to account for this diversity of responses. Understanding the roles of individual TLR pathways and the relationships between them and non-TLR innate immune pathways in the pathogenesis of diseases such as systemic lupus erythematosis highlights potential treatment targets for this spectrum of autoimmune diseases.