Systemic lupus erythematosus and the type I interferon system

Patients with systemic lupus erythematosus (SLE) have ongoing interferon-α (IFN-α) production and serum IFN-α levels are correlated with both disease activity and severity. Recent studies of patients with SLE have demonstrated the presence of endogenous IFN-α inducers in such individuals, consisting of small immune complexes (ICs) containing IgG and DNA. These ICs act specifically on natural IFN-α-producing cells (NIPCs), often termed plasmacytoid dendritic cells (PDCs). Given the fact that the NIPC/PDC has a key role in both the innate and adaptive immune response, as well as the many immunoregulatory effects of IFN-α, these observations might be important for the understanding of the etiopathogenesis of SLE. In this review we briefly describe the biology of the type I IFN system, with emphasis on inducers, producing cells (especially NIPCs/PDCs), IFN-α actions and target immune cells that might be relevant in SLE. On the basis of this information and results from studies in SLE patients, we propose a hypothesis that explains how NIPCs/PDCs become activated and have a pivotal etiopathogenic role in SLE. This hypothesis also indicates new therapeutic targets in this autoimmune disease.     

Cytokine polymorphisms influence treatment outcomes in SLE patients treated with antimalarial drugs

Antimalarial agents have been widely used as disease-modifying antirheumatic drugs in the treatment of systemic lupus erythematosus (SLE) and other rheumatological diseases, although their mechanism of action has not yet been fully defined. It is known, however, that effective response to treatment is variable among patients. Thus, the identification of genetic predictors of treatment response would provide valuable information for therapeutic intervention. The aim of the present study was to analyze the effect of antimalarial treatment on tumor necrosis factor (TNF)α serum levels and evaluate the possible influence of TNFα and IL-10 functional genetic polymorphisms on the response to antimalarial drugs. To this end, TNFα serum levels were quantified in 171 SLE patients and 215 healthy controls by ELISA techniques and polymorphisms at positions -1,082 and -308 of the IL-10 and TNFα gene promoterswere determined by PCR amplification followed by hybridization with fluorescent-labeled allele-specific probes in 192 SLE patients and 343 matched controls. Data were related to clinical features and treatment at the time of sampling and during the course of the disease. Results showed a significantly higher amount of serum TNFα in the entire SLE population compared with controls. However, TNFα serum levels correlated negatively with the use of antimalarial treatment during at least three months before sampling. Patients under single or combined treatment with these drugs had TNFα serum levels similar to healthy controls, whereas untreated patients and those under corticosteroid or immunosuppressive therapies had increased amounts of this cytokine. This suggests, however, that antimalarial-mediated inhibition of TNFα was only significant in patients who were genetically high TNFα or low IL-10 producers. In addition, evaluation of SLE patients administered antimalarial drugs for three or more years who did not require any other specific SLE treatment indicates that patients with the combined genotype low IL-10/high TNFα are the best responders to antimalarial therapy, developing mild disease with a good course under this treatment. In conclusion, we proposed that an antimalarial-mediated downregulation of TNFα levels in SLE patients is influenced by polymorphisms at IL-10 and TNFα promoters. Our results may thus find important clinical application through the identification of patients who are the most likely to benefit from antimalarial therapy.     

Trait-stratified genome-wide association study identifies novel and diverse genetic associations with serologic and cytokine phenotypes in systemic lupus erythematosus

Introduction  

Systemic lupus erythematosus (SLE) is a highly heterogeneous disorder, characterized by differences in autoantibody profile, serum cytokines, and clinical manifestations. SLE-associated autoantibodies and high serum interferon alpha (IFN-α) are important heritable phenotypes in SLE which are correlated with each other, and play a role in disease pathogenesis. These two heritable risk factors are shared between ancestral backgrounds. The aim of the study was to detect genetic factors associated with autoantibody profiles and serum IFN-α in SLE.     

Alpha-actinin-binding antibodies in relation to systemic lupus erythematosus and lupus nephritis

This study investigated the overall clinical impact of anti-α-actinin antibodies in patients with pre-selected autoimmune diseases and in a random group of anti-nuclear antibody (ANA)-positive individuals. The relation of anti-α-actinin antibodies with lupus nephritis and anti-double-stranded DNA (anti-dsDNA) antibodies represented a particular focus for the study. Using a cross-sectional design, the presence of antibodies to α-actinin was studied in selected groups, classified according to the relevant American College of Rheumatology classification criteria for systemic lupus erythematosus (SLE) (n = 99), rheumatoid arthritis (RA) (n = 68), Wegener's granulomatosis (WG) (n = 85), and fibromyalgia (FM) (n = 29), and in a random group of ANA-positive individuals (n = 142). Renal disease was defined as (increased) proteinuria with haematuria or presence of cellular casts. Sera from SLE, RA, and Sj?gren's syndrome (SS) patients had significantly higher levels of anti-α-actinin antibodies than the other patient groups. Using the geometric mean (± 2 standard deviations) in FM patients as the upper cutoff, 20% of SLE patients, 12% of RA patients, 4% of SS patients, and none of the WG patients were positive for anti-α-actinin antibodies. Within the SLE cohort, anti-α-actinin antibody levels were higher in patients with renal flares (p = 0.02) and correlated independently with anti-dsDNA antibody levels by enzyme-linked immunosorbent assay (p < 0.007) but not with other disease features. In the random ANA group, 14 individuals had anti-α-actinin antibodies. Of these, 36% had SLE, while 64% suffered from other, mostly autoimmune, disorders. Antibodies binding to α-actinin were detected in 20% of SLE patients but were not specific for SLE. They correlate with anti-dsDNA antibody levels, implying in vitro cross-reactivity of anti-dsDNA antibodies, which may explain the observed association with renal disease in SLE.     

Anti-<Emphasis Type="Italic">α</Emphasis>-actinin antibodies in relation to new-onset systemic lupus erythematosus and lupus nephritis

The aim of this study is to investigate the role of anti-α-actinin antibodies in patients with new-onset systemic lupus erythematosus (SLE). Thirty-six patients with SLE, 16 of whom had lupus nephritis (LN), and 53 healthy controls were included. The clinical and laboratory parameters of patients were collected from medical records or by questionnaire. Serum anti-α-actinin Abs was measured by competitive enzyme linked immunosorbent assay (ELISA). Our results show that the OD value of serum anti-α-actinin Abs in SLE patients was significantly lower than that in normal controls (1.212 ± 0.244 vs. 1.364 ± 0.202, P = 0.002); seven of 36 SLE patients were seropositive for anti-α-actinin Abs, which was significantly higher than in normal controls (19.4 vs. 3.8%, P = 0.028). There were no significant differences of clinical parameters between the anti-α-actinin Abs-positive patients and the negative patients. The positive rate of the term urine casts, elevated IgM and IgA in anti-α-actinin Abs-positive patients were higher than that in the negative patients. The OD values of serum anti-α-actinin Abs negatively correlated with disease activity (R _s = −0.352, P = 0.035). Anti-α-actinin Abs may be a useful marker of the disease activity of SLE; in addition, it may be used as a complementary parameter to differentiate LN from SLE without nephritis.     

Antitumor response of regional lymph node lymphocytes in human lung cancer

 Monoclonal antibodies (mAb) are promising substances for the treatment of colorectal carcinoma, but the efficiency of this therapy still needs further improvement. We used a flow-cytometric cytotoxicity test to determine the efficacy of the cytokines interferon α (IFNα) and γ (IFNγ), interleukin-2 (IL-2), macrophage-colony-stimulating factor (M-CSF), granulocyte/macrophage-CSF (GM-CSF) and tumor necrosis factor α (TNFα) in enhancing the antibody-dependent cellular cytoxicity (ADCC) of the mAb 17-1A and the mAb BR55-2 against the colorectal carcinoma cell line HT29. In experiments performed at an effector to target ratio of 9:1, with peripheral blood mononuclear cells from five healthy volunteers as effector cells, we found that IFNα, IFNγ and IL-2 significantly augmented the ADCC of both mAb at concentrations between 3 ng/ml and 30 ng/ml. The other three cytokines were not effective. In further experiments we examined combinations of the three effective cytokines in different concentrations. The combination of IFNα and IL-2 proved to be optimal in enhancing ADCC of both mAb. Thus, the examination of ADCC by flow cytometry may reveal potentially useful combinations of cytokines and mAb for the treatment of colorectal carcinoma. Received: 11 September 1997 / Accepted: 19 February 1998     

TWEAK as a target for therapy in systemic lupus erythematosus

Tumor necrosis factor (TNF)-like weak inducer of apoptosis (TWEAK) is a recently identified proinflammatory cytokine of the TNF superfamily. Through activation of the fibroblast growth factor-inducible 14 (Fn14) receptor, TWEAK regulates cell proliferation, cell death and inflammation. The available evidences have indicated that TWEAK might be a target for therapeutic intervention in renal, vascular injury and neuropathy. Since renal, vascular and neuropsychiatric complications are frequently encountered in systemic lupus erythematosus (SLE)—a systemic autoimmune disease, TWEAK-Fn14 pathway may be implicated in the pathogenesis of SLE. In this review, we will discuss the TWEAK-Fn14 pathway and the therapeutic potential of modulating this pathway in SLE.     

Cytokines and Absence Seizures in a Genetic Rat Model

We investigated the role of two cytokines, IL-1β and TNF-α, in the development of absence seizures using a genetic model of absence epilepsy in WAG/Rij rats. We administered these cytokines to animals systemically and measured the number of spike-wave discharges (SWDs) in the EEG. We also coadministered IL-1β with the GABA reuptake inhibitor tiagabine and measured the levels of IL-1β and TNF-α in the brain and blood plasma of 2-, 4-, and 6-month-old WAG/Rij rats and animals that served as a non-epileptic control (ACI). We found that IL-1β induced a significant increase in SWDs 2-5 h after administration, while TNF-α enhanced SWDs much later. Both cytokines enhanced passive behavior; body temperature was elevated only after TNF-α. The action of tiagabine was potentiated by earlier IL-1β injection, even when IL-1β was no longer active. Young WAG/Rij rats showed higher levels of TNF-α in blood serum than young ACI rats; the effects in the brain tended to be opposite. The marked differences in timing of the increase in SWDs suggest different time scales for the action of both cytokines tested. It is proposed that the results found after TNF-α are due to the de novo synthesis of IL-1β. TNF-α may possess neuroprotective effects. IL-1β might increase GABA-ergic neurotransmission. The changes in the efficacy of antiepileptic drugs related to changes in the cytokine systems may have some clinical relevance.     

Proinflammatory cytokines upregulate mRNA expression and secretion of vascular endothelial growth factor in cultured human airway smooth muscle cells

Airflow obstruction in chronic airway disease is associated with airway and pulmonary vascular remodeling, of which the molecular mechanisms are poorly understood. Paracrine actions of angiogenic factors released by resident or infiltrating inflammatory cells following activation by proinflammatory cytokines in diseased airways could play a major role in the airway vascular remodeling process. Here, the proinflammatory cytokines interleukin (IL)-1β, and tumor necrosis factor (TNF)-α were investigated on cell cultures of human airway smooth muscle (ASM) for their effects on mRNA induction and protein release of the angiogenic peptide, vascular endothelial growth factor (VEGF). IL-1β (0.5 ng/mL) and TNF-α (10ng/mL) each increased VEGF mRNA (3.9 and 1.7 kb) expression in human ASM cells, reaching maximal levels between 16 and 24 and 4 and 8h, respectively. Both cytokines also induced a time-dependent release of VEGF, which was not associated with increased ASM growth. Preincubation of cells with 1μM dexamethasone abolished enhanced release of VEGF by TNF-α. The data suggest that human ASM cells express and secrete VEGF in response to proinflammatory cytokines and may participate in paracrine inflammatory mechanisms of vascular remodeling in chronic airway disease.     

Deadly liaisons: fatal attraction between CCN matricellular proteins and the tumor necrosis factor family of cytokines

Recent studies have revealed an unexpected synergism between two seemingly unrelated protein families: CCN matricellular proteins and the tumor necrosis factor (TNF) family of cytokines. CCN proteins are dynamically expressed at sites of injury repair and inflammation, where TNF cytokines are also expressed. Although TNFα is an apoptotic inducer in some cancer cells, it activates NFκB to promote survival and proliferation in normal cells, and its cytotoxicity requires inhibition of de novo protein synthesis or NFκB signaling. The presence of CCN1, CCN2, or CCN3 overrides this requirement and unmasks the apoptotic potential of TNFα, thus converting TNFα from a proliferation-promoting protein into an apoptotic inducer. These CCN proteins also enhance the cytotoxicity of other TNF cytokines, including LTα, FasL, and TRAIL. Mechanistically, CCNs function through integrin α₆β₁ and the heparan sulfate proteoglycan (HSPG) syndecan-4 to induce reactive oxygen species (ROS) accumulation, which is essential for apoptotic synergism. Mutant CCN1 proteins defective for binding α₆β₁-HSPGs are unable to induce ROS or apoptotic synergism with TNF cytokines. Further, knockin mice that express an α₆β₁-HSPG-binding defective CCN1 are blunted in TNFα- and Fas-mediated apoptosis, indicating that CCN1 is a physiologic regulator of these processes. These findings implicate CCN proteins as contextual regulators of the inflammatory response by dictating or enhancing the cytotoxicity of TNFα and related cytokines.     

Topoisomerase II alpha as a universal tumor antigen: antitumor immunity in murine tumor models and H-2Kb-restricted T cell epitope

Topoisomerase II alpha (Top2α) is an attractive candidate to be used as a tumor antigen for cancer immunotherapy, because it is abundantly expressed in various tumors and serves as a target for a number of chemotherapeutic agents. In this study, we demonstrated the immunogenicity of Top2α, using dendritic cells (DC) electroporated with RNA encoding the Top2α C-terminus (Top2αCRNA/DC). Top2αCRNA/DC were able to demonstrate in vitro stimulation of T cells from mice that were previously vaccinated with Top2α-expressing tumor lysate-pulsed DC. Vaccination with Top2αCRNA/DC induced Top2α-specific T cell responses in vivo as well as antitumor effects in various murine tumor models including MC-38, B16F10, and GL26. DC pulsed with p1327 (DSDEDFSGL), defined as an epitope presented by H-2K^b, also induced Top2α-specific immune responses and antitumor effects. Based on these data, Top2α is suggested to be a universal target for cancer immunotherapy.     

The Role of Neurotrophins in Brain Aging: A Perspective in Honor of Regino Perez-Polo

During brain aging and progression of Alzheimer’s disease, the levels of Aβ and proinflammatory cytokines accumulate very early in the pathogenic process prior to any major degenerative changes. Accumulation of these molecules may impair with signal transduction pathways critical for neuronal health. Neurotrophin signaling is a critical mechanism involved in synaptic plasticity, learning and memory and neuronal health. We have recently shown that exposure to low levels of Aβ impairs BDNF trkB signal transduction, suppressing the Ras/ERK, and the PI3-K/Akt pathways but not the PLCγ pathway. As a result, downstream regulation of gene expression and neuronal viability are impaired. Recently, we have found that at least three agents – Aβ, TNFα, Il-1β – suppress TrkB signaling and act via a common and novel mechanism. These factors all regulate the docking proteins (e.g., IRS and Shc) that link the activated Trk receptor to downstream effectors. While this is a novel mechanism underlying regulation of Trk signaling, such a mechanism has been identified for the insulin/IGF-1 receptor in the presence of proinflammatory cytokines and is one of the mechanisms for insulin/IGF-resistance, which is a key risk factor for type II diabetes (1). We suggest that accumulation of AB and proinflammatory cytokines during aging generates in the brain a “neurotrophin resistance” state that places the brain at risk for cognitive decline and dementia.     

Prothymosin alpha: a ubiquitous polypeptide with potential use in cancer diagnosis and therapy

The thymus is a central lymphoid organ with crucial role in generating T cells and maintaining homeostasis of the immune system. More than 30 peptides, initially referred to as “thymic hormones,” are produced by this gland. Although the majority of them have not been proven to be thymus-specific, thymic peptides comprise an effective group of regulators, mediating important immune functions. Thymosin fraction five (TFV) was the first thymic extract shown to stimulate lymphocyte proliferation and differentiation. Subsequent fractionation of TFV led to the isolation and characterization of a series of immunoactive peptides/polypeptides, members of the thymosin family. Extensive research on prothymosin α (proTα) and thymosin α1 (Tα1) showed that they are of clinical significance and potential medical use. They may serve as molecular markers for cancer prognosis and/or as therapeutic agents for treating immunodeficiencies, autoimmune diseases and malignancies. Although the molecular mechanisms underlying their effect are yet not fully elucidated, proTα and Tα1 could be considered as candidates for cancer immunotherapy. In this review, we will focus in principle on the eventual clinical utility of proTα, both as a tumor biomarker and in triggering anticancer immune responses. Considering the experience acquired via the use of Tα1 to treat cancer patients, we will also discuss potential approaches for the future introduction of proTα into the clinical setting.     

Dysfunctional interferon-α production by peripheral plasmacytoid dendritic cells upon Toll-like receptor-9 stimulation in patients with systemic lupus erythematosus

Background  

It is well known that interferon (IFN)-α is important to the pathogenesis of systemic lupus erythematosus (SLE). However, several reports have indicated that the number of IFN-α producing cells are decreased or that their function is defective in patients with SLE. We studied the function of plasmacytoid dendritic cells (pDCs) under persistent stimulation of Toll-like receptor (TLR)9 via a TLR9 ligand (CpG ODN2216) or SLE serum.     

Detection of autoantibodies to cytokines

Autoantibodies to various cytokines have been reported in normal individuals and in patients with various infectious and immunoinflammatory disorders, and similar antibodies (Ab) may be induced in patients receiving human recombinant cytokines. The clinical relevance of these Ab is often difficult to evaluate. Not only are in vitro neutralizing cytokine Ab not necessarily neutralizing in vivo, but assays for binding and neutralizing Ab to cytokines are often difficult to interpret. For example, denaturation of immobilized cytokines in immunoblotting techniques and immunometric assays may leave Ab to the native forms of the mediators unrecognized. On the other hand, Ab may bind nonspecifically and/or with biologically irrelevant low affinities, leading to erroneous interpretations. This article describes in detail the use of radioimmunoassays that we have optimized and used successfully for the detection of high-affinity (auto)Ab to IL-1α, IL-6, GM-CSF, and IFNα.     

Elevated Inflammatory Markers in a Group of Amyotrophic Lateral Sclerosis Patients from Northern India

The role of cytokines in the pathophysiology of amyotrophic lateral sclerosis (ALS) and its relation to clinical outcome has not been clearly defined. We evaluated tumor necrosis factor-alpha (TNF-α), interferon-γ (IFN-γ) and nitric oxide (NO) levels in the serum of 22 ALS patients and 20 controls. Serum TNF-α levels and IFN-γ levels were significantly (P < 0.001) elevated in ALS patients. We also observed NO levels to be significantly (P < 0.05) increased with respect to normal subjects. We further noticed positive correlation between the duration of ALS and these proinflammatory molecule levels. Exitotoxicity and oxidative stress are known to play a crucial role in the neurodegeneration observed in ALS. Since high levels of TNF-α are known to be cytotoxic, it could be that a complex interplay of these effectors may be one of the factors underlying the progression of ALS. This study confirms the involvement of inflammation in ALS and the need to develop surrogate markers to check the progression of this disease.     

cis-Diamminedichloroplatinum and 5-fluorouracil are potent inducers of the cytokines and natural killer cell activity in vivo and in vitro

It has been reported that certain chemotherapeutic agents exhibit effects that enhance the antitumor host responses in the patients with malignant diseases. In the present study, we investigated whether cis-diamminedichloroplatinum (cisplatin) and 5-fluorouracil (5-FU) may induce cytokines and effector cells with antitumor efficacy in vivo and in vitro. The cultivation of human peripheral blood mononuclear cells (PBMC) in the presence of cisplatin (0–1.0 μg/ml) or 5-FU (0–5.0 μg/ml) resulted in the significant augmentation of natural killer (NK) and lymphokine-activated killer (LAK) cell activities as well as generation of interferon (IFN) γ, tumor necrosis factor (TNF) α, β, interleukin(IL)-1β, IL-6 and IL-12 in vitro. In addition, all of these activities were almost completely neutralized by addition of anti-asialoGM1 antibody and complement (P < 0.05). In an in vivo model, the administration of anti-asialoGM1 antibody significantly shortened the survival time extended by the treatment with cisplatin or 5-FU (P < 0.05), both on nude mice bearing salivary gland tumors and on syngeneic MethA-tumor-bearing BALB/c mice. Furthermore, high levels of NK and LAK activities and significant increases of the numbers of cells positive for asialoGM1, IFNγ, TNFα, or IL-1β were detected in the spleen cells derived from animals given cisplatin or 5-FU as compared with those given saline (P < 0.001–0.05). These findings clearly indicate that cisplatin and 5-FU are potent inducers of several types of cytokines and effector cells carrying antitumor activity mediated by asialoGM1-positive cells (mainly NK cells) for the most part, and that these abilities are closely associated with the in vivo antitumor effect of these agents. Received: 23 July 1998 / Accepted: 10 September 1998     

BAFF and innate immunity: new therapeutic targets for systemic lupus erythematosus

Recently, the B cell has emerged as a cornerstone of systemic lupus erythematosus (SLE) pathogenesis. This has been highlighted by studies of the cytokine B-cell-activating factor of the tumour necrosis factor (TNF) family (BAFF), a crucial factor regulating B-cell maturation, survival and function. Overexpression of BAFF in mice leads to the development of an SLE-like disease, independent of T cells but instead relying on innate immunity mechanisms. Moreover, BAFF has been shown to be elevated in the serum of patients suffering from autoimmune conditions, especially SLE, and may correlate with disease activity. These findings challenge the previous notion that T:B-cell collaboration is the sole driver of SLE. In recent years, controlled trials have for the first time tested targeted therapeutics for SLE. However, agents designed to target B cells failed to meet primary endpoints in clinical trials in SLE, suggesting that a more complex role for B cells in SLE awaited elucidation. By contrast, on 9 March 2011, the US Food and Drug Administration approved belimumab, a fully human anti-BAFF monoclonal antibody, as a new B-cell-specific treatment for SLE. This article will review over 10 years of research on the BAFF system, key findings that led to this recent positive clinical outcome and propose a model potentially explaining why this B-cell-specific therapy has yielded positive results in clinical trials. We will also review promising therapies presently in clinical trials targeting innate immunity, which are likely to revolutionize SLE management towards a personalized and targeted therapy approach.