Treatment of systemic lupus erythematosus: new therapeutic avenues and blind alleys

Inhibition of polymorphonuclear cells averts cytotoxicity against hypoimmune cells in xenotransplantation

Allogeneic, immune-evasive hypoimmune (HIP) cell therapeutics that are HLA-depleted and overexpress CD47 create the opportunity to treat immunocompetent patients with cancer, degenerative, or autoimmune diseases. However, HIP cell therapy has not yet been established for xenotransplantation. Here we engineer, for human-to-non-human primate studies, human HIP* endothelial cells (EC) that are HLA-depleted and express macaque CD47 to allow compatibility with the macaque SIRPα immune checkpoint. Although no T cell, NK cell, or macrophage responses and no antibody-dependent cytotoxicity is observed in cynomolgus recipients, we reveal that macaque polymorphonuclear cells (PMN) show strong xenogeneic cytotoxicity against HIP* ECs. Inhibition of PMN killing using a multi-drug regimen leads to improved xenogeneic human HIP* EC survival in cynomolgus monkeys. Similarly, human PMNs show xenoreactivity against pig ECs, which has implications for clinical xenotransplantation. Accordingly, our engineered pig HIP* ECs that are SLA-depleted, overexpress human CD47, and additionally overexpress the PMN-inhibitory ligands CD99 and CD200, are protected against all human adaptive and innate cytotoxicity, including PMNs. In summary, specific targeting of PMN-mediated killing of the transplanted cells might improve outcomes for clinical pig-to-human xenotransplantation.

MDIC3: Matrix decomposition to infer cell-cell communication

Crosstalk among cells is vital for maintaining the biological function and intactness of systems. Most existing methods for investigating cell-cell communications are based on ligand-receptor (L-R) expression, and they focus on the study between two cells. Thus, the final communication inference results are particularly sensitive to the completeness and accuracy of the prior biological knowledge. Because existing L-R research focuses mainly on humans, most existing methods can only examine cell-cell communication for humans. As far as we know, there is currently no effective method to overcome this species limitation. Here, we propose MDIC3 (matrix decomposition to infer cell-cell communication), an unsupervised tool to investigate cell-cell communication in any species, and the results are not limited by specific L-R pairs or signaling pathways. By comparing it with existing methods for the inference of cell-cell communication, MDIC3 obtained better performance in both humans and mice.

Obexelimab in Systemic Lupus Erythematosus With Exploration of Response Based on Gene Pathway Co-Expression Patterns: A Double-Blind, Randomized, Placebo-Controlled, Phase 2 Trial

OBJECTIVE

Obexelimab is an investigational, bifunctional, noncytolytic monoclonal antibody that binds CD19 and FcyRIIb to inhibit B cells, plasmablasts, and plasma cells. This trial evaluated the efficacy and safety of obexelimab in the treatment of patients with systemic lupus erythematosus (SLE).

METHODS

During screening, patients with active, non-organ-threatening SLE received corticosteroid injections to ameliorate symptoms while immunosuppressants were withdrawn (≤10 mg/day prednisone equivalent and ≤400 mg/day hydroxychloroquine allowed). Patients with improved disease activity were randomized 1:1 to obexelimab 5 mg/kg intravenously or placebo once every 2 weeks until week 32 or loss of improvement (LOI).

RESULTS

In this study, 104 patients were randomized. Analysis of the primary endpoint, proportion of patients reaching week 32 without LOI, used an efficacy-evaluable (EE) population defined as patients who completed the study or withdrew for flare or treatment-related toxicity. This endpoint did not reach statistical significance: 21 of 50 obexelimab-treated patients (42.0%) versus 12 of 42 patients (28.6%) treated with a placebo (P = 0.183). Time to LOI was increased in obexelimab-treated patients versus patients treated with a placebo in the EE (hazard ratio [HR] 0.53, P = 0.025) and intention-to-treat (HR 0.59, P = 0.062) populations. In obexelimab-treated patients, B cells decreased approximately 50%, and trough concentration and inclusion in baseline gene expression clusters with high B cell pathway modules were associated with increased time to LOI. Obexelimab was associated with infusion reactions but was generally safe and well-tolerated.

CONCLUSION

Although the primary endpoint was not reached, secondary analysis showed time to LOI was significantly increased in obexelimab-treated patients, and analysis of patient subsets defined by gene expression patterns at baseline suggests a responding subpopulation.

Endoplasmic Reticulum Stress in Systemic Lupus Erythematosus and Lupus Nephritis: Potential Therapeutic Target

Systemic lupus erythematosus (SLE) is a complex autoimmune disease. Approximately one-third to two-thirds of the patients with SLE progress to lupus nephritis (LN). The pathogenesis of SLE and LN has not yet been fully elucidated, and effective treatment for both conditions is lacking. The endoplasmic reticulum (ER) is the largest intracellular organelle and is a site of protein synthesis, lipid metabolism, and calcium storage. Under stress, the function of ER is disrupted, and the accumulation of unfolded or misfolded proteins occurs in ER, resulting in an ER stress (ERS) response. ERS is involved in the dysfunction of B cells, macrophages, T cells, dendritic cells, neutrophils, and other immune cells, causing immune system disorders, such as SLE. In addition, ERS is also involved in renal resident cell injury and contributes to the progression of LN. The molecular chaperones, autophagy, and proteasome degradation pathways inhibit ERS and restore ER homeostasis to improve the dysfunction of immune cells and renal resident cell injury. This may be a therapeutic strategy for SLE and LN. In this review, we summarize advances in this field.

Integrative Analysis of m6A Regulator-Mediated RNA Methylation Modification Patterns and Immune Characteristics in Lupus Nephritis

Background

There is growing evidence to demonstrate that the epigenetic regulation of immune characteristics, especially for N6-methyladenosine (m⁶A) RNA methylation. However, how m⁶A methylation is involved in lupus nephritis (LN) is still unclear. This study aimed to determine the role of m⁶A RNA methylation and their association with the immune microenvironment in LN.

Methods

In total, 87 glomeruli (73 LN, 14 living healthy donors), 110 tubulointerstitium (95 LN, 15 living healthy donors), and 21 kidney whole tissue samples (14 LN, 7 controls) were included in our research to evaluate the expression levels of m⁶A regulators. CIBERSORT was used to assess the abundance of infiltrating immunocytes. The m⁶A regulator gene signature for LN was identified using LASSO-logistic regression and verified with external data. Consensus clustering algorithms were used for the unsupervised cluster analysis of m⁶A modification patterns in LN. Single-sample gene-set enrichment analysis and gene set variation analysis algorithms were employed to assess the activity of immune responses and other functional pathways. Weighted gene co-expression network analysis and protein-protein interaction networks were used to identify m⁶A methylation markers. Lastly, the Nephroseq V5 tool was used to analyze the correlation between m⁶A markers and renal function.

Results

We found that the expression of m⁶A regulators was more significantly different in the glomeruli in LN compared with tubulointerstitium and whole kidney tissue. We established an m⁶A regulator signature, comprised of METTL3, WTAP, YTHDC2, YTHDF1, FMR1, and FTO, that can easily distinguish LN and healthy individuals. Two distinct m⁶A modification patterns based on 18 m⁶A regulators were determined, with significant differences in m⁶A regulator expression, immune microenvironment, biological functional pathways, and clinical characteristics. Activated NK cells, most immune responses, and HLA genes had strong correlations with m⁶A regulators. Seven m⁶A markers were identified and demonstrated a meaningful correlation with GFR, indicating that they are potential prognostic biomarkers.

Conclusion

This study emphasized that m⁶A RNA methylation and the immune microenvironment are closely linked in LN. A better understanding of m⁶A modification patterns provide a basis for the development of novel therapeutic options for LN.

Integrated multi-omics approaches to improve classification of chronic kidney disease

Chronic kidney diseases (CKDs) are currently classified according to their clinical features, associated comorbidities and pattern of injury on biopsy. Even within a given classification, considerable variation exists in disease presentation, progression and response to therapy, highlighting heterogeneity in the underlying biological mechanisms. As a result, patients and clinicians experience uncertainty when considering optimal treatment approaches and risk projection. Technological advances now enable large-scale datasets, including DNA and RNA sequence data, proteomics and metabolomics data, to be captured from individuals and groups of patients along the genotype-phenotype continuum of CKD. The ability to combine these high-dimensional datasets, in which the number of variables exceeds the number of clinical outcome observations, using computational approaches such as machine learning, provides an opportunity to re-classify patients into molecularly defined subgroups that better reflect underlying disease mechanisms. Patients with CKD are uniquely poised to benefit from these integrative, multi-omics approaches since the kidney biopsy, blood and urine samples used to generate these different types of molecular data are frequently obtained during routine clinical care. The ultimate goal of developing an integrated molecular classification is to improve diagnostic classification, risk stratification and assignment of molecular, disease-specific therapies to improve the care of patients with CKD.

The immune cell landscape in kidneys of patients with lupus nephritis

Lupus nephritis is a potentially fatal autoimmune disease for which the current treatment is ineffective and often toxic. To develop mechanistic hypotheses of disease, we analyzed kidney samples from patients with lupus nephritis and from healthy control subjects using single-cell RNA sequencing. Our analysis revealed 21 subsets of leukocytes active in disease, including multiple populations of myeloid cells, T cells, natural killer cells and B cells that demonstrated both pro-inflammatory responses and inflammation-resolving responses. We found evidence of local activation of B cells correlated with an age-associated B-cell signature and evidence of progressive stages of monocyte differentiation within the kidney. A clear interferon response was observed in most cells. Two chemokine receptors, CXCR4 and CX3CR1, were broadly expressed, implying a potentially central role in cell trafficking. Gene expression of immune cells in urine and kidney was highly correlated, which would suggest that urine might serve as a surrogate for kidney biopsies.

Up-Regulation of TLR7-Mediated IFN-α Production by Plasmacytoid Dendritic Cells in Patients With Systemic Lupus Erythematosus

Objectives: Aberrant and persistent production of interferon-α (IFN-α) by plasmacytoid dendritic cells (pDCs) is known to play a key role in the pathogenesis of systemic lupus erythematosus (SLE). To assess the precise function of pDCs in SLE patients, we investigated the differential regulation of Toll-like receptor 7 (TLR7) and TLR9 responses during IFN-α production by pDCs.

Methods: Peripheral blood mononuclear cells (PBMCs) in SLE patients without hydroxychloroquine treatment, rheumatoid arthritis patients and heathy controls were stimulated with TLR7 and TLR9 agonists. To investigate the priming effect by cytokines, PBMCs from healthy controls were pre-treated with various cytokines and stimulated with TLR7 and TLR9 agonists. The IFN-α production in pDCs was detected by flow cytometry.

Results: TLR7-mediated IFN-α production was up-regulated and correlated positively with disease activity in SLE. Conversely, TLR9-mediated IFN-α production was down-regulated. Differential regulation of TLR7/9 response in SLE was independent of TLR7 and TLR9 expression levels. Furthermore, in vitro experiments indicated that TLR7-mediated IFN-α production was up-regulated by pre-treatment with type I IFN, whereas TLR9-mediated IFN-α production was down-regulated by pre-treatment with type II IFN.

Conclusions: Our study indicates the association between up-regulation of TLR7- mediated IFN-α production by pDCs and disease activity and that TLR7 and TLR9 responses were reversely regulated on pDCs in SLE patients. Thus, type I IFN and TLR7-mediated IFN-α production were involved in a vicious cycle, causing hyper production of IFN-α by pDCs during the pathogenic processes of SLE.

Mesenchymal stem cell transplantation in systemic lupus erythematous, a mesenchymal stem cell disorder

Systemic lupus erythematosus (SLE) is a chronic autoimmune and inflammatory disorder with involvement of several organs and systems such as the kidney, lung, brain and the hematopoietic system. As the most prevailing organ manifestation, lupus nephritis is the major cause of mortality and morbidity in SLE patients. The most classically and widely administered immunosuppressive medications, namely corticosteroids and cyclophosphamide, have eventuated in a remarkable amelioration in disease complications over the last few years and reduced the progression to end-stage multiorgan failure. Mesenchymal stem cells (MSCs) are considered as non-hematopoietic and multipotential progenitor cells, which are able to differentiate into multiple cell lineages such as chondrocytes, osteoblasts, myoblasts, endothelial cells, adipocytes, neuron-like cells, hepatocytes and cardiomyocytes. MSCs from SLE patients have demonstrated defects such as aberrant cytokine production. Moreover, impaired phenotype, growth and immunomodulatory functions of MSCs from patients with SLE in comparison to healthy controls have been reported. Therefore, it is hypothesized that SLE is potentially an MSC-mediated disease and, as a result, allogeneic rather than autologous MSC transplantation can be argued to be a potentially advantageous therapy for patients with SLE. On the other hand, the MSC senescence phenomenon may meet the current therapeutic approaches with challenges and demand more attention. Here, we discuss MSC transplantations to date in animal models and humans and focus on the MSC senescence complications in SLE patients.

Lupus community panel proposals for optimising clinical trials: 2018

Formidable impediments stand in the way of treatment development for lupus. These include the unwieldy size of current trials, international competition for scarce patients, complex outcome measures and a poor understanding of these outcomes in the world at large. The heterogeneity of the disease itself coupled to superimposition of variegated background polypharmacy has created enough immunological noise to virtually ensure the failure of lupus treatment trials, leaving an understandable suspicion that at least some of the results in testing failed drugs over the years may not have been negative, but merely uninterpretable. The authors have consulted with many clinical trial investigators, biopharmaceutical developers and stakeholders from government and voluntary sectors. This paper examines the available evidence that supports workable trial designs and proposes approaches to improve the odds of completing interpretable treatment development programs for lupus.

Update on Biologic Therapies for Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a chronic multisystemic autoimmune disease driven by genetic, hormonal, and environmental factors. Despite the advances in diagnostic and therapeutic approaches in the last decades, SLE still leads to significant morbidity and increased mortality. Although a cure for SLE is still unknown, treatment is required to control acute disease exacerbation episodes (flares), decrease the frequency and severity of subsequent lupus flares, address comorbidities, and prevent end-organ damage. While conventional SLE pharmacotherapy may exhibit suboptimal efficacy and substantial toxicity, a growing knowledge of the disease pathogenesis enabled the research on novel therapeutic agents directed at specific disease-related targets. In this paper, we review the recent progress in the clinical investigation of biologic agents targeting B cells, T cells, cytokines, innate immunity, and other immunologic or inflammatory pathways. Although many investigational agents exhibited insufficient efficacy or inadequate safety in clinical trials, one of them, belimumab, fulfilled the efficacy and safety regulatory requirements and was approved for the treatment of SLE in Europe and the USA, which confirms that, despite all difficulties, advances in this field are possible.

Natural Modulators of Endosomal Toll-Like Receptor-Mediated Psoriatic Skin Inflammation

Psoriasis is a chronic inflammatory autoimmune disease that can be initiated by excessive activation of endosomal toll-like receptors (TLRs), particularly TLR7, TLR8, and TLR9. Therefore, inhibitors of endosomal TLR activation are being investigated for their ability to treat this disease. The currently approved biological drugs adalimumab, etanercept, infliximab, ustekinumab, ixekizumab, and secukizumab are antibodies against effector cytokines that participate in the initiation and development of psoriasis. Several immune modulatory oligonucleotides and small molecular weight compounds, including IMO-3100, IMO-8400, and CPG-52364, that block the interaction between endosomal TLRs and their ligands are under clinical investigation for their effectiveness in the treatment of psoriasis. In addition, several chemical compounds, including AS-2444697, PF-05387252, PF-05388169, PF-06650833, ML120B, and PHA-408, can inhibit TLR signaling. Although these compounds have demonstrated anti-inflammatory activity in animal models, their therapeutic potential for the treatment of psoriasis has not yet been tested. Recent studies demonstrated that natural compounds derived from plants, fungi, and bacteria, including mustard seed, Antrodia cinnamomea extract, curcumin, resveratrol, thiostrepton, azithromycin, and andrographolide, inhibited psoriasis-like inflammation induced by the TLR7 agonist imiquimod in animal models. These natural modulators employ different mechanisms to inhibit endosomal TLR activation and are administered via different routes. Therefore, they represent candidate psoriasis drugs and might lead to the development of new treatment options.

Identification of biomarkers of response to abatacept in patients with SLE using deconvolution of whole blood transcriptomic data from a phase IIb clinical trial

Objective

To characterise patients with active SLE based on pretreatment gene expression-defined peripheral immune cell patterns and identify clusters enriched for potential responders to abatacept treatment.

Methods

This post hoc analysis used baseline peripheral whole blood transcriptomic data from patients in a phase IIb trial of intravenous abatacept (~10 mg/kg/month). Cell-specific genes were used with a published deconvolution algorithm to identify immune cell proportions in patient samples, and unsupervised consensus clustering was generated. Efficacy data were re-analysed.

Results

Patient data (n=144: abatacept: n=98; placebo: n=46) were grouped into four main clusters (C) by predominant characteristic cells: C1—neutrophils; C2—cytotoxic T cells, B-cell receptor-ligated B cells, monocytes, IgG memory B cells, activated T helper cells; C3—plasma cells, activated dendritic cells, activated natural killer cells, neutrophils; C4—activated dendritic cells, cytotoxic T cells. C3 had the highest baseline total British Isles Lupus Assessment Group (BILAG) scores, highest antidouble-stranded DNA autoantibody levels and shortest time to flare (TTF), plus trends in favour of response to abatacept over placebo: adjusted mean difference in BILAG score over 1 year, −4.78 (95% CI −12.49 to 2.92); median TTF, 56 vs 6 days; greater normalisation of complement component 3 and 4 levels. Differential improvements with abatacept were not seen in other clusters, except for median TTF in C1 (201 vs 109 days).

Conclusions

Immune cell clustering segmented disease severity and responsiveness to abatacept. Definition of immune response cell types may inform design and interpretation of SLE trials and treatment decisions.

Trial registration number

NCT00119678; results.

A Novel Mechanism for Generating the Interferon Signature in Lupus: Opsonization of Dead Cells by Complement and IgM

OBJECTIVE

In vitro studies suggest that the type I interferon (IFN) signature seen in most lupus patients results from Fcγ receptor-mediated uptake of nucleic acid-containing immune complexes by plasmacytoid dendritic cells and engagement of endosomal Toll-like receptors. The aim of this study was to reexamine the pathogenesis of the IFN signature in vivo.

METHODS

Lupus was induced in mice by injecting pristane. Some mice were treated with normal immunoglobulin or with cobra venom factor to deplete complement. The IFN signature was evaluated by polymerase chain reaction. The IFN signature also was determined in C4-deficient patients and control subjects.

RESULTS

Wild-type C57BL/6 mice with pristane-induced lupus developed a strong IFN signature, which was absent in immunoglobulin-deficient (μMT), C3^-/- , and CD18^-/- mice. Intravenous infusion of normal IgM, but not IgG, restored the IFN signature in μMT mice, and the IFN signature in wild-type mice was inhibited by depleting complement, suggesting that opsonization by IgM and complement is involved in IFN production. Consistent with that possibility, the levels of "natural" IgM antibodies reactive with dead cells were increased in pristane-treated wild-type mice compared with untreated controls, and in vivo phagocytosis of dead cells was impaired in C3-deficient mice. To examine the clinical relevance of these findings, we identified 10 C4-deficient patients with lupus-like disease and compared them with 152 C4-intact patients and 21 healthy controls. In comparison with C4-intact patients, C4-deficient patients had a different clinical/serologic phenotype and lacked the IFN signature.

CONCLUSION

These studies define previously unrecognized roles of natural IgM, complement, and complement receptors in generating the IFN signature in lupus.

A new benzenediamine derivative modulates Toll-like receptors-induced myeloid dendritic cells activation and ameliorates lupus-like syndrome in MRLlpr/lpr mice

Modulators of the over-activation of myeloid dendritic cells (mDCs) by Toll-like receptors (TLRs) have an advantage in the treatment of systemic lupus erythematosus (SLE). This study was designed to evaluate the effects of FC-99, a novel benzenediamine derivative, on TLR-induced activation of mDCs, and to assess the efficacy of FC-99 in a murine model of SLE. In vitro, FC-99 inhibited the phenotypic (CD40 and MHC-II) and functional activation (IL-12 and CXCL10) of mDCs induced by TLR ligands. In vivo, MRLlpr/lpr mice displayed renal diseases associated with increased levels of proteinuria and immunoglobulin, which were ameliorated by FC-99. Enhanced accumulation and activation of mDCs in lymphoid organs was also impaired by FC-99. Additionally, FC-99 inhibited the activation of IκB-α and upregulated the expression of TNFα-induced protein 3 (TNFAIP3) in vitro and in vivo. These results indicate that FC-99 modulates TLR-induced activation of mDCs and ameliorates lupus-like syndrome in MRLlpr/lpr mice. This effect is closely associated with the inhibition of IκB-α and upregulation of TNFAIP3.

Discerning Risk of Disease Transition in Relatives of Systemic Lupus Erythematosus Patients Utilizing Soluble Mediators and Clinical Features

OBJECTIVE

Systemic lupus erythematosus (SLE) and other autoimmune diseases cause significant morbidity. Identifying populations at risk of developing SLE is essential for curtailing irreversible inflammatory damage. The aim of this study was to identify factors associated with transition to classified disease that would inform our understanding of the risk of SLE.

METHODS

Previously identified blood relatives of patients with SLE, who had <4 American College of Rheumatology (ACR) classification criteria for SLE at baseline, were enrolled in this follow-up study (n = 409 unaffected relatives). Participants provided detailed family, demographic, and clinical information, including the SLE-specific portion of the Connective Tissue Disease Screening Questionnaire (SLE-CSQ). Serum and plasma samples were tested for the presence of lupus-associated autoantibodies and 52 soluble mediators. Generalized estimating equations (GEEs) were applied to identify factors predictive of disease transition.

RESULTS

Of the 409 unaffected relatives of SLE patients, 45 (11%) had transitioned to classified SLE at follow-up (mean time to follow-up 6.4 years). Relatives who transitioned to SLE displayed more lupus-associated autoantibody specificities and higher SLE-CSQ scores (P < 0.0001) at baseline than did relatives who did not transition. Importantly, those who had developed SLE during the follow-up period also had elevated baseline plasma levels of inflammatory mediators, including B lymphocyte stimulator, stem cell factor (SCF), and interferon-associated chemokines (P ≤ 0.02), with concurrent decreases in the levels of regulatory mediators, transforming growth factor β (TGFβ), and interleukin-10 (P ≤ 0.03). GEE analyses revealed that baseline SLE-CSQ scores or ACR scores (number of ACR criteria satisfied) and plasma levels of SCF and TGFβ, but not autoantibodies, were significant and independent predictors of SLE transition (P ≤ 0.03).

CONCLUSION

Preclinical alterations in levels of soluble mediators may predict transition to classified disease in relatives of SLE patients. Thus, immune perturbations precede SLE classification and can help identify high-risk relatives for rheumatology referral and potential enrollment in prevention trials.

Aberrant Epigenetic Regulation in the Pathogenesis of Systemic Lupus Erythematosus and Its Implication in Precision Medicine

Great progress has been made in the last decades in understanding the complex immune dysregulation in systemic lupus erythematosus (SLE), yet the efforts to pursue an effective treatment of SLE proved to be futile. The pathoetiology of SLE involves extremely complicated and multifactorial interaction among various genetic and epigenetic factors. Multiple gene loci predispose to disease susceptibility, and the interaction with epigenetic modifications mediated through sex, hormones, and the hypothalamo-pituitary-adrenal axis complicates susceptibility and manifestations of this disease. Finally, certain environmental and psychological factors probably trigger the disease via epigenetic mechanisms. In this review, we summarize and discuss recent epigenetic studies of SLE and suggest a personalized approach to the dissection of disease onset and therapy or precision medicine. We speculate that in the future, precision medicine based on epigenetic and genetic information could help guide more effective targeted therapeutic intervention.

Success and failure of biological treatment in systemic lupus erythematosus: A critical analysis

Patients affected with systemic lupus erythematosus (SLE) still display increased mortality and decreased quality of life in respect to general population. The major determinant of poor long term prognosis is organ damage, which is predictive of more damage and death. Damage is in turn triggered by uncontrolled disease activity and especially by the long-standing corticosteroid use which often accompanies SLE patients over their disease course, owing both to the need of reaching disease remission and to the habit of keeping patients on a small steroid dose for an indefinite period of time. Hence, the need for new drugs and therapeutic strategies aiming at minimizing damage accrual through a better control of disease activity and a steroid-sparing potential is paramount. So far, however, the therapeutic strategy in SLE requires a multitarget approach which is not devoid of widespread immunesuppression. In fact, several studies have been carried out in recent years targeting both the adaptive and the innate immune system, the majority of which did not achieve their primary endpoint, being often divergent from successful clinical experience and thereby committing physician to off-label use of targeted therapies in face of refractory SLE manifestations. The study designs and the chosen endpoints were often blamed for inadequacy, being at least in part responsible for study failures. In this review, we go over major clinical trials conducted in SLE by analyzing any critical aspects related to study design, predefined endpoints and biological activity of novel compounds that may have hampered study outcome, despite the great effort of providing less toxic drugs within a targeted, pathogenic-based approach.

New therapeutic avenues in SLE

Although the use of corticosteroids and immunosuppressive agents such as cyclophosphamide and mycophenolate has led to reduced mortality in systemic lupus erythematosus (SLE), there is a need for development of new biologic agents to improve outcomes further. The pathogenesis of SLE involves many components of the immune system, notably B cells, T cells, cytokines and innate immunity, which are potential targets for the new biologic therapies. In this study, the rationale for the development of new therapies in SLE and the progress that has been made in each direction of therapy are described. Most progress has been made with agents directed against B cells, especially rituximab and belimumab and the latter has been the subject of two successful randomised clinical trials (RCTs). Anti-T-cell and anti-cytokine therapies are further back in the development process, but promising advances can be anticipated over the next decade.

Inducible T-cell co-stimulator ligand (ICOSL) blockade leads to selective inhibition of anti-KLH IgG responses in subjects with systemic lupus erythematosus

Objectives

To evaluate the safety, tolerability, pharmacokinetics (PK) and pharmacodynamics (PD) of single-dose and multiple-dose administration of AMG 557, a human anti-inducible T cell co-stimulator ligand (ICOSL) monoclonal antibody, in subjects with systemic lupus erythematosus (SLE).

Methods

Patients with mild, stable SLE (n=112) were enrolled in two clinical trials to evaluate the effects of single (1.8–210 mg subcutaneous or 18 mg intravenous) and multiple (6 –210 mg subcutaneous every other week (Q2W)×7) doses of AMG 557. Subjects received two 1 mg intradermal injections 28 days apart of keyhole limpet haemocyanin (KLH), a neoantigen, to assess PD effects of AMG 557. Safety, PK, target occupancy, anti-KLH antibody responses, lymphocyte subset analyses and SLE-associated biomarkers and clinical outcomes were assessed.

Results

AMG 557 demonstrated an acceptable safety profile. The PK properties were consistent with an antibody directed against a cell surface target, with non-linear PK observed at lower concentrations and linear PK at higher concentrations. Target occupancy by AMG 557 was dose dependent and reversible, and maximal occupancy was achieved in the setting of this trial. Anti-AMG 557 antibodies were observed, but none were neutralising and without impact on drug levels. A significant reduction in the anti-KLH IgG response was observed with AMG 557 administration without discernible changes in the anti-KLH IgM response or on the overall IgG levels. No discernible changes were seen in lymphocyte subsets or in SLE-related biomarkers and clinical measures.

Conclusions

The selective reduction in anti-KLH IgG demonstrates a PD effect of AMG 557 in subjects with SLE consistent with the biology of the ICOS pathway and supports further studies of AMG 557 as a potential therapeutic for autoimmune diseases.

Trial registration numbers

NCT02391259 and NCT00774943.

A Phase II study of the efficacy and safety of rontalizumab (rhuMAb interferon-α) in patients with systemic lupus erythematosus (ROSE)

OBJECTIVES

To examine the safety and efficacy of rontalizumab, a humanised IgG1 anti-interferon α (anti-IFN-α) monoclonal antibody, in patients with moderate-to-severe systemic lupus erythematosus (SLE).

METHODS

Patients with active SLE were randomised (2:1) to 750 mg intravenous rontalizumab every 4 weeks or placebo (Part 1), and 300 mg subcutaneous rontalizumab every 2 weeks or placebo (Part 2).

BACKGROUND

Hydroxychloroquine and corticosteroids were allowed. Patients taking immunosuppressants at baseline were required per protocol to discontinue. Efficacy end points included reduction in disease activity by British Isles Lupus Disease Activity Group (BILAG)-2004 (primary), and SLE response index (SRI, secondary) at Week 24. Efficacy was also examined by an exploratory measure of IFN-regulated gene expression (interferon signature metric, ISM).

RESULTS

Patients (n=238) received rontalizumab (n=159) or placebo (n=79). At baseline, the mean Safety of Estrogens in Lupus Erythematosus National Assessment version of the SLE Disease Activity Index (SELENA-SLEDAI) score in all cohorts was ~10, and 75.6% of patients had a high ISM (ISM-High). Efficacy response rates by BILAG and SRI were similar between rontalizumab and placebo groups. However, in the exploratory subgroup of ISM-Low patients, SRI response was higher and steroid use was lower in the rontalizumab-treated patients. There was also a reduction in SELENA-SLEDAI flare index rates (HR 0.61, 0.46 to 0.81, p=0.004) in this subgroup. Adverse events were similar between placebo and rontalizumab groups.

CONCLUSIONS

The primary and secondary end points of this trial were not met in all patients or in patients with high ISM scores. In an exploratory analysis, rontalizumab treatment was associated with improvements in disease activity, reduced flares and decreased steroid use in patients with SLE with low ISM scores.

TRIAL REGISTRATION NUMBER

NCT00962832.

Overcoming challenges in the diagnosis and treatment of myasthenia gravis

In recent years, the discovery of new autoantigens and the use of sensitive assays have expanded the clinical spectrum of myasthenia gravis (MG). In particular, antibodies binding to clustered acetylcholine receptors and to the low-density lipoprotein receptor-related protein 4 have not only bridged a significant gap in diagnosis but also have relevant clinical implications. MG management includes different therapeutic options, from symptomatic agents as the only therapy in mildly affected cases to combined long-term immunosuppression and thymectomy in patients with severe disabling disease. MG biological diversity can influence the response to therapies and should be taken into account when planning treatment. Biologic agents are promising, though their use is currently limited to patients with refractory disease.

Predominant Role of Plasmacytoid Dendritic Cells in Stimulating Systemic Autoimmunity

Plasmacytoid dendritic cells (pDCs), which are prominent type I interferon (IFN-I)-producing immune cells, have been extensively implicated in systemic lupus erythematosus (SLE). However, whether they participate critically in lupus pathogenesis remains unknown. Recent studies using various genetic and cell type-specific ablation strategies have demonstrated that pDCs play a pivotal role in the development of autoantibodies and the progression of lupus under diverse experimental conditions. The findings of several investigations highlight a notion that pDCs operate critically at the early stage of lupus development. In particular, pDCs have a profound effect on B-cell activation and humoral autoimmunity in vivo. This deeper understanding of the vital role of pDCs in lupus pathogenesis supports the therapeutic targeting of the pDC-IFN-I pathway in SLE.

Neutrophils Regulate Humoral Autoimmunity by Restricting Interferon-γ Production via the Generation of Reactive Oxygen Species

Here, we examine the mechanism by which plasmacytoid dendritic cells (pDCs) and type I interferons promote humoral autoimmunity. In an amyloid-induced experimental autoimmune model, neutrophil depletion enhanced anti-nuclear antibody development, which correlated with heightened IFN-γ production by natural killer (NK) cells. IFN-α/β produced by pDCs activated NK cells via IL-15 induction. Neutrophils released reactive oxygen species (ROS), which negatively modulated the levels of IL-15, thereby inhibiting IFN-γ production. Mice deficient in NADPH oxidase 2 produced increased amounts of IFN-γ and developed augmented titers of autoantibodies. Both the pDC-IFN-α/β pathway and IFN-γ were indispensable in stimulating humoral autoimmunity. Male NZB/W F1 mice expressed higher levels of superoxide than their female lupus-prone siblings, and depletion of neutrophils resulted in spontaneous NK cell and autoimmune B cell activation. Our findings suggest a regulatory role for neutrophils in vivo and highlight the importance of an NK-IFN-γ axis downstream of the pDC-IFN-α/β pathway in systemic autoimmunity.

Rituximab in systemic lupus erythematosus and lupus nephritis

Treatment options for systemic lupus erythematosus (SLE) and lupus nephritis (LN) have high associated morbidity and mortality. Side effects, particularly from long-term corticosteroid usage, limit patient adherence, with subsequent impacts on treatment efficacy. In addition, a subset of patients with SLE/LN fails to respond to current standard immunotherapy. There is an urgent need to develop steroid-sparing treatment regimens as well as novel therapies for the management of refractory disease. Rituximab is a chimeric mouse/human monoclonal antibody directed against the B cell CD20 receptor. It has been used in the treatment of non-Hodgkin's lymphoma for over 30 years and has an excellent safety profile. Recent work has demonstrated a role for B cell depletion therapy in the management of autoimmune disease, and the efficacy of rituximab in many observational studies in SLE and LN has been noted. Unfortunately, two large randomised controlled trials evaluating rituximab for the treatment of renal and non-renal lupus failed to meet their primary endpoints. Reasons for this have been discussed extensively within the medical community with a general consensus that trial design (steroid use, trial size and endpoints used) was the principal reason for the failures. Despite the lack of trial evidence, clinical experience means many physicians firmly believe in the value of rituximab in SLE/LN treatment and have continued to use it in their clinical practice. Recent work has demonstrated the efficacy of rituximab as a steroid-sparing agent and as an alternative therapeutic option for refractory SLE/LN. There are two further rituximab randomised controlled trials planned/started in LN – one using a steroid-minimising regimen with rituximab for induction and one evaluating rituximab for LN refractory to 6 months standard of care treatment. Rituximab remains a problematic drug in lupus and LN – it is a biologically plausible agent with a huge amount of supportive anecdotal clinical data. Yet the completed trials have been negative to date despite clinical experience strongly suggesting efficacy. It is hoped that the two new trials will determine the role for rituximab, at least in LN.

Glutamate receptor antibodies in neurological diseases: anti-AMPA-GluR3 antibodies, anti-NMDA-NR1 antibodies, anti-NMDA-NR2A/B antibodies, anti-mGluR1 antibodies or anti-mGluR5 antibodies are present in subpopulations of patients with either: epilepsy, encephalitis, cerebellar ataxia, systemic lupus erythematosus (SLE) and neuropsychiatric SLE, Sjogren's syndrome, schizophrenia, mania or stroke. These autoimmune anti-glutamate receptor antibodies can bind neurons in few brain regions, activate glutamate receptors, decrease glutamate receptor's expression, impair glutamate-induced signaling and function, activate blood brain barrier endothelial cells, kill neurons, damage the brain, induce behavioral/psychiatric/cognitive abnormalities and ataxia in animal models, and can be removed or silenced in some patients by immunotherapy

Glutamate is the major excitatory neurotransmitter of the Central Nervous System (CNS), and it is crucially needed for numerous key neuronal functions. Yet, excess glutamate causes massive neuronal death and brain damage by excitotoxicity--detrimental over activation of glutamate receptors. Glutamate-mediated excitotoxicity is the main pathological process taking place in many types of acute and chronic CNS diseases and injuries. In recent years, it became clear that not only excess glutamate can cause massive brain damage, but that several types of anti-glutamate receptor antibodies, that are present in the serum and CSF of subpopulations of patients with a kaleidoscope of human neurological diseases, can undoubtedly do so too, by inducing several very potent pathological effects in the CNS. Collectively, the family of anti-glutamate receptor autoimmune antibodies seem to be the most widespread, potent, dangerous and interesting anti-brain autoimmune antibodies discovered up to now. This impression stems from taking together the presence of various types of anti-glutamate receptor antibodies in a kaleidoscope of human neurological and autoimmune diseases, their high levels in the CNS due to intrathecal production, their multiple pathological effects in the brain, and the unique and diverse mechanisms of action by which they can affect glutamate receptors, signaling and effects, and subsequently impair neuronal signaling and induce brain damage. The two main families of autoimmune anti-glutamate receptor antibodies that were already found in patients with neurological and/or autoimmune diseases, and that were already shown to be detrimental to the CNS, include the antibodies directed against ionotorpic glutamate receptors: the anti-AMPA-GluR3 antibodies, anti-NMDA-NR1 antibodies and anti-NMDA-NR2 antibodies, and the antibodies directed against Metabotropic glutamate receptors: the anti-mGluR1 antibodies and the anti-mGluR5 antibodies. Each type of these anti-glutamate receptor antibodies is discussed separately in this very comprehensive review, with regards to: the human diseases in which these anti-glutamate receptor antibodies were found thus far, their presence and production in the nervous system, their association with various psychiatric/behavioral/cognitive/motor impairments, their possible association with certain infectious organisms, their detrimental effects in vitro as well as in vivo in animal models in mice, rats or rabbits, and their diverse and unique mechanisms of action. The review also covers the very encouraging positive responses to immunotherapy of some patients that have either of the above-mentioned anti-glutamate receptor antibodies, and that suffer from various neurological diseases/problems. All the above are also summarized in the review's five schematic and useful figures, for each type of anti-glutamate receptor antibodies separately. The review ends with a summary of all the main findings, and with recommended guidelines for diagnosis, therapy, drug design and future investigations. In the nut shell, the human studies, the in vitro studies, as well as the in vivo studies in animal models in mice, rats and rabbit revealed the following findings regarding the five different types of anti-glutamate receptor antibodies: (1) Anti-AMPA-GluR3B antibodies are present in ~25-30% of patients with different types of Epilepsy. When these anti-glutamate receptor antibodies (or other types of autoimmune antibodies) are found in Epilepsy patients, and when these autoimmune antibodies are suspected to induce or aggravate the seizures and/or the cognitive/psychiatric/behavioral impairments that sometimes accompany the seizures, the Epilepsy is called 'Autoimmune Epilepsy'. In some patients with 'Autoimmune Epilepsy' the anti-AMPA-GluR3B antibodies associate significantly with psychiatric/cognitive/behavior abnormalities. In vitro and/or in animal models, the anti-AMPA-GluR3B antibodies by themselves induce many pathological effects: they activate glutamate/AMPA receptors, kill neurons by 'Excitotoxicity', and/or by complement activation modulated by complement regulatory proteins, cause multiple brain damage, aggravate chemoconvulsant-induced seizures, and also induce behavioral/motor impairments. Some patients with 'Autoimmune Epilepsy' that have anti-AMPA-GluR3B antibodies respond well (although sometimes transiently) to immunotherapy, and thanks to that have reduced seizures and overall improved neurological functions. (2) Anti-NMDA-NR1 antibodies are present in patients with autoimmune 'Anti-NMDA-receptor Encephalitis'. In humans, in animal models and in vitro the anti-NMDA-NR1 antibodies can be very pathogenic since they can cause a pronounced decrease of surface NMDA receptors expressed in hippocampal neurons, and also decrease the cluster density and synaptic localization of the NMDA receptors. The anti-NMDA-NR1 antibodies induce these effects by crosslinking and internalization of the NMDA receptors. Such changes can impair glutamate signaling via the NMDA receptors and lead to various neuronal/behavior/cognitive/psychiatric abnormalities. Anti-NMDA-NR1 antibodies are frequently present in high levels in the CSF of the patients with 'Anti-NMDA-receptor encephalitis' due to their intrathecal production. Many patients with 'Anti-NMDA receptor Encephalitis' respond well to several modes of immunotherapy. (3) Anti-NMDA-NR2A/B antibodies are present in a substantial number of patients with Systemic Lupus Erythematosus (SLE) with or without neuropsychiatric problems. The exact percentage of SLE patients having anti-NMDA-NR2A/B antibodies varies in different studies from 14 to 35%, and in one study such antibodies were found in 81% of patients with diffuse 'Neuropshychiatric SLE', and in 44% of patients with focal 'Neuropshychiatric SLE'. Anti-NMDA-NR2A/B antibodies are also present in subpopulations of patients with Epilepsy of several types, Encephalitis of several types (e.g., chronic progressive limbic Encephalitis, Paraneoplastic Encephalitis or Herpes Simplex Virus Encephalitis), Schizophrenia, Mania, Stroke, or Sjorgen syndrome. In some patients, the anti-NMDA-NR2A/B antibodies are present in both the serum and the CSF. Some of the anti-NMDA-NR2A/B antibodies cross-react with dsDNA, while others do not. Some of the anti-NMDA-NR2A/B antibodies associate with neuropsychiatric/cognitive/behavior/mood impairments in SLE patients, while others do not. The anti-NMDA-NR2A/B antibodies can undoubtedly be very pathogenic, since they can kill neurons by activating NMDA receptors and inducing 'Excitotoxicity', damage the brain, cause dramatic decrease of membranal NMDA receptors expressed in hippocampal neurons, and also induce behavioral cognitive impairments in animal models. Yet, the concentration of the anti-NMDA-NR2A/B antibodies seems to determine if they have positive or negative effects on the activity of glutamate receptors and on the survival of neurons. Thus, at low concentration, the anti-NMDA-NR2A/B antibodies were found to be positive modulators of receptor function and increase the size of NMDA receptor-mediated excitatory postsynaptic potentials, whereas at high concentration they are pathogenic as they promote 'Excitotoxcity' through enhanced mitochondrial permeability transition. (4) Anti-mGluR1 antibodies were found thus far in very few patients with Paraneoplastic Cerebellar Ataxia, and in these patients they are produced intrathecally and therefore present in much higher levels in the CSF than in the serum. The anti-mGluR1 antibodies can be very pathogenic in the brain since they can reduce the basal neuronal activity, block the induction of long-term depression of Purkinje cells, and altogether cause cerebellar motor coordination deficits by a combination of rapid effects on both the acute and the plastic responses of Purkinje cells, and by chronic degenerative effects. Strikingly, within 30 min after injection of anti-mGluR1 antibodies into the brain of mice, the mice became ataxic. Anti-mGluR1 antibodies derived from patients with Ataxia also caused disturbance of eye movements in animal models. Immunotherapy can be very effective for some Cerebellar Ataxia patients that have anti-mGluR1 antibodies. (5) Anti-mGluR5 antibodies were found thus far in the serum and CSF of very few patients with Hodgkin lymphoma and Limbic Encephalopathy (Ophelia syndrome). The sera of these patients that contained anti-GluR5 antibodies reacted with the neuropil of the hippocampus and cell surface of live rat hippocampal neurons, and immunoprecipitation from cultured neurons and mass spectrometry demonstrated that the antigen was indeed mGluR5. Taken together, all these evidences show that anti-glutamate receptor antibodies are much more frequent among various neurological diseases than ever realized before, and that they are very detrimental to the nervous system. As such, they call for diagnosis, therapeutic removal or silencing and future studies. What we have learned by now about the broad family of anti-glutamate receptor antibodies is so exciting, novel, unique and important, that it makes all future efforts worthy and essential.

When biologics should be used in systemic lupus erythematosus?

Recently, the use and evaluation of biologics increased in systemic lupus erythematosus (SLE). However, no international recommendation is available concerning the use of biologics with regards to the subset of patients who should be treated, the optimal time to treat, the objective of treatment and the manner to discontinue it. To address these complex questions, we focused on biologics already evaluated in at least two published randomized controlled trials. We summarized the results of these trials and available observational data in registries. Taking into account the clinical evidence, we proposed some guidance on the way biologics could be used in SLE. Many areas of uncertainty persist and require intensifying efforts from the academic world to set up new trials, and develop international recommendations.

Clinical trials in systemic lupus erythematosus: a status report on ongoing trials

To describe the characteristics of trials in systemic lupus erythematous (SLE) listed in ClinicalTrials.gov such as study design, funding sources and aspects of the disease and drugs under investigation. We conducted a survey of ongoing clinical trials that were registered in the ClinicalTrials.gov website. We used the advanced search option and applied the following inclusion criteria, "SLE," "open studies," "interventional," and "adults 18 years or older." Of 97 eligible studies, 34.0 % were phase 3 or 4, 49.5 % were phase 1, 2 or 2/3 and in 16.5 %, we could not determine the study phase. Most trials were randomized (69.0 %) and 48.4 % were double blinded; 34 % of the trials were placebo controlled, 19.6 % had an active agent comparator and 46.4 % had no comparator. Universities and pharmaceutical industries were the primary sponsors for 45.3 and 39.1 % of the trials, respectively, and government agencies for 10.3 %. Multi-center trials based in the USA (US) accounted for 40.2 % of the trials, 46.4 % were outside of the US and 13.4 % were in the US as well as other countries. The most frequently used endpoint was drug efficacy (30.9 %) followed by disease severity indices (25.7 %), drug safety (14.4 %), remission rates and times to remission (7.2 %), and inflammatory markers and antibody titers (7.2 %). The majority of ongoing clinical trials in SLE are university or industry-funded, randomized phase 1, 2, or 2/3 trials, focused on drug efficacy. Federal funding for trials in SLE within and outside the US remains low.