Anti-interleukin-6 monoclonal antibody inhibits autoimmune responses in a murine model of systemic lupus erythematosus

Targeting Inflammatory Imbalance in Chronic Kidney Disease: Focus on Anti-Inflammatory and Resolution Mediators

Chronic kidney disease (CKD) is a condition caused by the gradual decline of renal function that approximatively affects 10-12% of the world population, thus representing a public health priority. In CKD patients, chronic and systemic low-grade inflammation is observed, and it significantly contributes to disease development and progression, especially for patients with advanced disease. It also results in CKD-associated complications and increased mortality. The low-grade inflammation is due to different factors, such as the decline of glomerular filtration rate, increased immune system activation, reactive oxygen species release, and intestinal homeostasis. Therefore, the possibility to control chronic low-grade inflammation in CKD deserves great attention. In this review, we will examine the current possible pharmacological approaches to counteract the inflammatory state in CKD, focusing our attention both on the pro-inflammatory factors and the pro-resolving mediators involved in CKD inflammatory state.

Lymphocytes Change Their Phenotype and Function in Systemic Lupus Erythematosus and Lupus Nephritis

Systemic lupus erythematosus (SLE) is a complex autoimmune disease, characterized by considerable changes in peripheral lymphocyte structure and function, that plays a critical role in commencing and reviving the inflammatory and immune signaling pathways. In healthy individuals, B lymphocytes have a major role in guiding and directing defense mechanisms against pathogens. Certain changes in B lymphocyte phenotype, including alterations in surface and endosomal receptors, occur in the presence of SLE and lead to dysregulation of peripheral B lymphocyte subpopulations. Functional changes are characterized by loss of self-tolerance, intra- and extrafollicular activation, and increased cytokine and autoantibody production. T lymphocytes seem to have a supporting, rather than a leading, role in the disease pathogenesis. Substantial aberrations in peripheral T lymphocyte subsets are evident, and include a reduction of cytotoxic, regulatory, and advanced differentiated subtypes, together with an increase of activated and autoreactive forms and abnormalities in follicular T cells. Up-regulated subpopulations, such as central and effector memory T cells, produce pre-inflammatory cytokines, activate B lymphocytes, and stimulate cell signaling pathways. This review explores the pivotal roles of B and T lymphocytes in the pathogenesis of SLE and Lupus Nephritis, emphasizing the multifaceted mechanisms and interactions and their phenotypic and functional dysregulations.

Translating Lupus: Comparative Transcriptional Profiles of Preclinical Lupus Models and Their Relevance to Human Disease

Systemic lupus erythematosus (SLE) is a chronic, systemic autoimmune disease which can present with mixed organ involvement. Kidney involvement in lupus nephritis (LN) is a severe complication and major cause of mortality in SLE patients, second only to cardiovascular disease. While mouse models have helped uncover some molecular pathways involved in SLE/LN, we need a better understanding of the connection of these pathways and the immune cells involved in disease pathogenesis to develop new and effective therapies. Furthermore, models used for studying SLE/LN in mice have a heterogeneous immune response and may not always represent disease manifestations observed in patients. Identifying models that have shared pathways with human disease would allow for better translation for developing effective SLE/LN therapies. The molecular pathways of five different SLE/LN models (MRL/lpr, poly (I:C)-induced, interferon-α-induced, bm12 GvHD, and spontaneous NZB/W F1) were compared to characterize the immune response in mouse kidneys. These models demonstrated varied magnitudes in immune responses and proportions of innate vs. adaptive cell involvement. These findings were compared to human molecular pathways and cell types from public databases, including the Accelerating Medicine Partnership-Systemic Lupus Erythematosus Program (AMP-SLE), to help corelate mechanisms involved in mouse models to human disease.

IL-6 Inhibition as a Therapeutic Target in Aged Experimental Autoimmune Encephalomyelitis

Multiple sclerosis (MS) onset at an advanced age is associated with a higher risk of developing progressive forms and a greater accumulation of disability for which there are currently no effective disease-modifying treatments. Immunosenescence is associated with the production of the senescence-associated secretory phenotype (SASP), with IL-6 being one of the most prominent cytokines. IL-6 is a determinant for the development of autoimmunity and neuroinflammation and is involved in the pathogenesis of MS. Herein, we aimed to preclinically test the therapeutic inhibition of IL-6 signaling in experimental autoimmune encephalomyelitis (EAE) as a potential age-specific treatment for elderly MS patients. Young and aged mice were immunized with myelin oligodendrocyte protein (MOG)35-55 and examined daily for neurological signs. Mice were randomized and treated with anti-IL-6 antibody. Inflammatory infiltration was evaluated in the spinal cord and the peripheral immune response was studied. The blockade of IL-6 signaling did not improve the clinical course of EAE in an aging context. However, IL-6 inhibition was associated with an increase in the peripheral immunosuppressive response as follows: a higher frequency of CD4 T cells producing IL-10, and increased frequency of inhibitory immune check points PD-1 and Tim-3 on CD4+ T cells and Lag-3 and Tim-3 on CD8+ T cells. Our results open the window to further studies aimed to adjust the anti-IL-6 treatment conditions to tailor an effective age-specific therapy for elderly MS patients.

Autoimmune Responses and Therapeutic Interventions for Systemic Lupus Erythematosus: A Comprehensive Review

Systemic Lupus Erythematosus (SLE) or Lupus is a multifactorial autoimmune disease of multiorgan malfunctioning of extremely heterogeneous and unclear etiology that affects multiple organs and physiological systems. Some racial groups and women of childbearing age are more susceptible to SLE pathogenesis. Impressive progress has been made towards a better understanding of different immune components contributing to SLE pathogenesis. Recent investigations have uncovered the detailed mechanisms of inflammatory responses and organ damage. Various environmental factors, pathogens, and toxicants, including ultraviolet light, drugs, viral pathogens, gut microbiome metabolites, and sex hormones trigger the onset of SLE pathogenesis in genetically susceptible individuals and result in the disruption of immune homeostasis of cytokines, macrophages, T cells, and B cells. Diagnosis and clinical investigations of SLE remain challenging due to its clinical heterogeneity and hitherto only a few approved antimalarials, glucocorticoids, immunosuppressants, and some nonsteroidal anti-inflammatory drugs (NSAIDs) are available for treatment. However, the adverse effects of renal and neuropsychiatric lupus and late diagnosis make therapy challenging. Additionally, SLE is also linked to an increased risk of cardiovascular diseases due to inflammatory responses and the risk of infection from immunosuppressive treatment. Due to the diversity of symptoms and treatment-resistant diseases, SLE management remains a challenging issue. Nevertheless, the use of next-generation therapeutics with stem cell and gene therapy may bring better outcomes to SLE treatment in the future. This review highlights the autoimmune responses as well as potential therapeutic interventions for SLE particularly focusing on the recent therapeutic advancements and challenges.

Exploiting the neonatal crystallizable fragment receptor to treat kidney disease

The neonatal Fc receptor (FcRn) was initially discovered as the receptor that allowed passive immunity in newborns by transporting maternal IgG through the placenta and enterocytes. Since its initial discovery, FcRn has been found to exist throughout all stages of life and in many different cell types. Beyond passive immunity, FcRn is necessary for intrinsic albumin and IgG recycling and is important for antigen processing and presentation. Given its multiple important roles, FcRn has been utilized in many disease treatments including a new class of agents that were developed to inhibit FcRn for treatment of a variety of autoimmune diseases. Certain cell populations within the kidney also express high levels of this receptor. Specifically, podocytes, proximal tubule epithelial cells, and vascular endothelial cells have been found to utilize FcRn. In this review, we summarize what is known about FcRn and its function within the kidney. We also discuss how FcRn has been used for therapeutic benefit, including how newer FcRn inhibiting agents are being used to treat autoimmune diseases. Lastly, we will discuss what renal diseases may respond to FcRn inhibitors and how further work studying FcRn within the kidney may lead to therapies for kidney diseases.

Anti-complement factor H (CFH) autoantibodies could delay pristane-induced lupus nephritis

PURPOSE

Anti-complement factor H (CFH) autoantibodies could be detected in lupus and its significance remained to be elucidated. Herein, we aimed to explore the roles of anti-CFH autoantibodies based on pristane-induced lupus mice.

METHODS

Twenty-four female Balb/c mice were randomly divided into four groups, with one group injected with pristane (pristane group), one group with pristane and then human CFH (hCFH) (pristane-CFH group) 3 times, and the other two as vertical controls, PBS group and PBS-CFH group. Histopathological analysis was performed six months after pristane administration. Levels of hCFH, anti-CFH autoantibodies and anti-dsDNA antibody were detected. Murine IgG (mIgG) were purified and cross-reactivity, epitopes, subclasses and functional analysis were further evaluated in vitro.

RESULTS

Immunization with hCFH and subsequent development of anti-CFH autoantibodies significantly attenuated nephritis of pristane-induced lupus, including lower levels of urinary protein and serum creatinine, decreased levels of serum anti-dsDNA antibody, greatly ameliorated renal histopathologic damage, decreased IgG, complements (C1q, C3) deposits and lower inflammatory factor (IL-6) expression in glomerulus. Furthermore, the purified mIgG (contained anti-CFH autoantibodies) could recognize both hCFH and murine CFH, and the epitopes were predominantly located in hCFH short consensus repeats (SCRs) 1-4, 7 and 11-14. The IgG subclasses were predominant IgG1. The autoantibodies could enhance the binding between hCFH and C3b, and increase factor I mediated-C3b lysis in vitro.

CONCLUSION

Our results suggested that anti-CFH autoantibodies could attenuate pristane-induced lupus nephritis by increasing bio-functions of CFH on regulating complement activation and controlling inflammation.

A quinazoline derivative suppresses B cell hyper-activation and ameliorates the severity of systemic lupus erythematosus in mice

Background: Aberrant autoreactive B cell responses contribute to the pathogenesis of systemic lupus erythematosus (SLE). Currently, there is no safe and effective drug for intervention of SLE. Quinazoline derivative (N4-(4-phenoxyphenethyl)quinazoline-4,6-diamine, QNZ) is a NF-κB inhibitor and has potent anti-inflammatory activity. However, it is unclear whether QNZ treatment can modulate B cell activation and SLE severity. Methods: Splenic CD19⁺ B cells were treated with QNZ (2, 10, or 50 nM) or paeoniflorin (200 μM, a positive control), and their activation and antigen presentation function-related molecule expression were examined by flow cytometry. MRL/lpr lupus-prone mice were randomized and treated intraperitoneally with vehicle alone, 0.2 mg/kg/d QNZ or 1 mg/kg/d FK-506 (tacrolimus, a positive control) for 8 weeks. Their body weights and clinical symptoms were measured and the frequency of different subsets of splenic and lymph node activated B cells were quantified by flow cytometry. The degrees of kidney inflammation and glycogen deposition were examined by hematoxylin and eosin (H&E) and PAS staining. The levels of serum autoantibodies and renal IgG, complement C3 deposition were examined by ELISA and immunofluorescence. Results: QNZ treatment significantly inhibited the activation and antigen presentation-related molecule expression of B cells in vitro. Similarly, treatment with QNZ significantly mitigated the SLE activity by reducing the frequency of activated B cells and plasma cells in MRL/lpr mice. Conclusion: QNZ treatment ameliorated the severity of SLE in MRL/lpr mice, which may be associated with inhibiting B cell activation, and plasma cell formation. QNZ may be an excellent candidate for the treatment of SLE and other autoimmune diseases.

Updated insight into the role of Th2-associated immunity in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease with multiple organs involvement, abundant autoantibodies, complement activation, and immune complexes depositions. By regulating inflammation and immune homeostasis, cytokines have been well documented to participate in the pathogenesis of SLE. A number of studies have shown that T helper 2 (Th2)-associated immunity plays an important role in autoimmune diseases, including SLE. Key molecules underlying Th2-related immunity are expected to serve as promising targets for the diagnosis and targeted treatment of SLE. Current progress in SLE pathogenesis and biological treatment strategies has been reviewed, focusing on the latest development in Th2-associated immunity.

Self-assembled aluminum oxyhydroxide nanorices with superior suspension stability for vaccine adjuvant

The suspension stability of aluminum-based adjuvant (Alum) plays an important role in determining the Alum-antigen interaction and vaccine efficacy. Inclusion of excipients has been shown to stabilize antigens in vaccine formulations. However, there is no mechanistic study to tune the characteristics of Alum for improved suspension stability. Herein, a library of self-assembled rice-shaped aluminum oxyhydroxide nanoadjuvants i.e., nanorices (NRs), was synthesized through intrinsically controlled crystallization and atomic coupling-mediated aggregations. The NRs exhibited superior suspension stability in both water and a saline buffer. After adsorbing hepatitis B surface antigen (HBsAg) virus-like particles (VLPs), human papillomavirus virus (HPV) VLPs, or bovine serum albumin, NR-antigen complexes exhibited less sedimentation. Further mechanistic study demonstrated that the improved suspension stability was due to intraparticle aggregations that led to the reduction of the surface free energy. By using HBsAg in a murine vaccination model, NRs with higher aspect ratios elicited more potent humoral immune responses. Our study demonstrated that engineered control of particle aggregation provides a novel material design strategy to improve suspension stability for a diversity of biomedical applications.

Isolevuglandins disrupt PU.1-mediated C1q expression and promote autoimmunity and hypertension in systemic lupus erythematosus

We describe a mechanism responsible for systemic lupus erythematosus (SLE). In humans with SLE and in 2 SLE murine models, there was marked enrichment of isolevuglandin-adducted proteins (isoLG adducts) in monocytes and dendritic cells. We found that antibodies formed against isoLG adducts in both SLE-prone mice and humans with SLE. In addition, isoLG ligation of the transcription factor PU.1 at a critical DNA binding site markedly reduced transcription of all C1q subunits. Treatment of SLE-prone mice with the specific isoLG scavenger 2-hydroxybenzylamine (2-HOBA) ameliorated parameters of autoimmunity, including plasma cell expansion, circulating IgG levels, and anti-dsDNA antibody titers. 2-HOBA also lowered blood pressure, attenuated renal injury, and reduced inflammatory gene expression uniquely in C1q-expressing dendritic cells. Thus, isoLG adducts play an essential role in the genesis and maintenance of systemic autoimmunity and hypertension in SLE.

Cell type-specific mechanistic target of rapamycin-dependent distortion of autophagy pathways in lupus nephritis

Pro-inflammatory immune system development, metabolomic defects, and deregulation of autophagy play interconnected roles in driving the pathogenesis of systemic lupus erythematosus (SLE). Lupus nephritis (LN) is a leading cause of morbidity and mortality in SLE. While the causes of SLE have not been clearly delineated, skewing of T and B cell differentiation, activation of antigen-presenting cells, production of antinuclear autoantibodies and pro-inflammatory cytokines are known to contribute to disease development. Underlying this process are defects in autophagy and mitophagy that cause the accumulation of oxidative stress-generating mitochondria which promote necrotic cell death. Autophagy is generally inhibited by the activation of the mammalian target of rapamycin (mTOR), a large protein kinase that underlies abnormal immune cell lineage specification in SLE. Importantly, several autophagy-regulating genes, including ATG5 and ATG7, as well as mitophagy-regulating HRES-1/Rab4A have been linked to lupus susceptibility and molecular pathogenesis. Moreover, genetically-driven mTOR activation has been associated with fulminant lupus nephritis. mTOR activation and diminished autophagy promote the expansion of pro-inflammatory Th17, Tfh and CD3⁺CD4^-CD8^- double-negative (DN) T cells at the expense of CD8⁺ effector memory T cells and CD4⁺ regulatory T cells (Tregs). mTOR activation and aberrant autophagy also involve renal podocytes, mesangial cells, endothelial cells, and tubular epithelial cells that may compromise end-organ resistance in LN. Activation of mTOR complexes 1 (mTORC1) and 2 (mTORC2) has been identified as biomarkers of disease activation and predictors of disease flares and prognosis in SLE patients with and without LN. This review highlights recent advances in molecular pathogenesis of LN with a focus on immuno-metabolic checkpoints of autophagy and their roles in pathogenesis, prognosis and selection of targets for treatment in SLE.

Interleukin 6 in diabetes, chronic kidney disease and cardiovascular disease: mechanisms and therapeutic perspectives

INTRODUCTION

Diabetes, chronic kidney disease (CKD) and cardiovascular disease (CVD) are cardiometabolic diseases that remain amongst the leading causes of morbidity and premature mortality. Here, we review the current understanding of how anti-inflammatory intervention via inhibition of the pro-inflammatory but pleiotropic cytokine interleukin (IL) 6 may benefit patients with these or related diseases or complications.

AREAS COVERED

Based on a PubMed literature search, this review integrates and contextualizes evidence regarding the clinical utility of anti-IL-6 intervention in the treatment of cardiometabolic diseases, as well as of the associated condition non-alcoholic hepatosteatosis.

EXPERT OPINION

Evidence implicates the pro-inflammatory effects of IL-6 in the pathophysiology of diabetes, CKD and CVD. Thus, targeting the IL-6 pathway holds a therapeutic potential in these cardiometabolic disorders. However, because IL-6 has multiple homeostatic roles, antagonizing this cytokine may be associated with side effects such as increased risk of infection as seen with other anti-inflammatory drugs. Additional studies are required to establish the benefit-risk profile of anti-IL-6 intervention in the cardiometabolic diseases, whilst also considering alternative interventions such as lifestyle changes. IL-6 is also elevated in NASH, but the clinical usefulness of targeting IL-6 in this hepatic disorder remains largely unexplored.

Discovery of NEU1 as a candidatedone. renal biomarker for proliferative lupus nephritis chronicity

OBJECTIVE

Proteomic approach was applied to identify candidate biomarkers of chronicity in patients with proliferative lupus nephritis (LN), and their clinicopathological significance and prognostic values were investigated.

METHODS

This study recruited 10 patients with proliferative LN and 6 normal controls (NCs) with proteomic data to compare protein expression profiles, 58 patients with proliferative LN and 10 NCs to verify proteomic data by immunohistochemistry, and 14 patients with proliferative LN with urine samples to evaluate the urinary expression of the biomarker by western blot assay. The composite endpoints included end-stage renal disease and ≥50% reduction from baseline estimated glomerular filtration rate (eGFR).

RESULTS

Proteomics detected 48 proteins upregulated in the group with chronicity index (CI) ≥1 compared with the CI=0 and NC groups. Further pathway analysis was enriched in 'other glycan degradation'. Neuraminidase 1 (NEU1), the most predominant protein in the pathway of other glycan degradation, was highly expressed in the kidney of patients with proliferative LN and could co-localise with podocyte, mesangial cells, endothelial cells and tubule cells. NEU1 expression in the tubulointerstitium area was significantly higher in the CI ≥1 group compared with the CI=0 and NC groups. Moreover, NEU1 expression was significantly correlated with serum creatinine value, eGFR and CI scores, respectively. Urinary NEU1 excretion in the CI ≥1 group was higher than in the CI=0 group and was also positively correlated with CI scores. Furthermore, the high expression of renal NEU1 was identified as an independent risk factor for renal prognosis by multivariate Cox regression analysis (HR, 6.462 (95% CI 1.025 to 40.732), p=0.047).

CONCLUSIONS

Renal NEU1 expression was associated with pathological CI scores and renal outcomes in patients with proliferative LN.

Advances in therapeutic targets-related study on systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a chronic and autoimmunity-mediated diffuse connective tissue disease. The mainstay of treatments for SLE mainly relies on corticosteroids and immunosuppressants, which have a series of unavoidable side effects. Therefore, it is of fundamental importance to search novel therapeutic targets for better treatment with favorable efficacy and minor side effects. Recent studies shed light on potential therapeutic targets for SLE, mainly covering the followings: B-cell/plasmocyte-related targets [B cell activating factor (BAFF), a proliferation-inducing ligand (APRIL), CD20, CD22, CD19/FcγRIIb, Bruton tyrosine kinase (Btk), and proteasome], T cell-related targets [calcineurin, mammalian target of rapamycin (mTOR), regulatory factor X1 (RFX1), and Rho kinase], macrophage-related targets (macrophage migration inhibitory factor), intracellular signaling molecules, cytokines (cereblon, histone deacetylase 6, Janus activated kinase/signal transducer and activator of transcription), co-stimulating factors (CD28/B7, CD40/CD154), IgE autoantibody, and gut microbiome. Among them, belimumab (a humanized monoclonal antibody against B-lymphocyte stimulator) and telitacicept (a recombinant human B-lymphocyte stimulator receptor-antibody fusion protein) have been sequentially approved for the clinical treatment of SLE in China. A variety of new targeted-therapy drugs are in the Phase 2 or Phase 3 clinical trials,among which anifrolumab (a human monoclonal antibody against type I interferon receptor subunit 1) has completed a Phase 3 clinical trial with good responses achieved, although its incidence of herpes zoster is higher than that in the control group. The research progress in both molecular mechanisms and new drug development for different therapeutic targets have greatly promoted our better and in-depth understanding of the pathogenesis of SLE, and have also reflected the complexity and heterogeneity of the disease. Successful development and clinical application of more novel therapies would no doubt usher in a new era of individualized treatment for SLE in the future.

Role of Macrophages and Related Cytokines in Kidney Disease

Inflammation is a key characteristic of kidney disease, but this immune response is two-faced. In the acute phase of kidney injury, there is an activation of the immune cells to fight against the insult, contributing to kidney repair and regeneration. However, in chronic kidney diseases (CKD), immune cells that infiltrate the kidney play a deleterious role, actively participating in disease progression, and contributing to nephron loss and fibrosis. Importantly, CKD is a chronic inflammatory disease. In early CKD stages, patients present sub-clinical inflammation, activation of immune circulating cells and therefore, anti-inflammatory strategies have been proposed as a common therapeutic target for renal diseases. Recent studies have highlighted the plasticity of immune cells and the complexity of their functions. Among immune cells, monocytes/macrophages play an important role in all steps of kidney injury. However, the phenotype characterization between human and mice immune cells showed different markers; therefore the extrapolation of experimental studies in mice could not reflect human renal diseases. Here we will review the current information about the characteristics of different macrophage phenotypes, mainly focused on macrophage-related cytokines, with special attention to the chemokine CCL18, and its murine functional homolog CCL8, and the macrophage marker CD163, and their role in kidney pathology.

Meant to B: B cells as a therapeutic target in systemic lupus erythematosus

B cells have a prominent role in the pathogenesis of systemic lupus erythematosus (SLE). They are mediators of inflammation through the production of pathogenic antibodies that augment inflammation and cause direct tissue and cell damage. Multiple therapeutic agents targeting B cells have been successfully used in mouse models of SLE; however, these preclinical studies have led to approval of only one new agent to treat patients with SLE: belimumab, a monoclonal antibody targeting B cell-activating factor (BAFF). Integrating the experience acquired from previous clinical trials with the knowledge generated by new studies about mechanisms of B cell contributions to SLE in specific groups of patients is critical to the development of new treatment strategies that will help to improve outcomes in patients with SLE. In particular, a sharper focus on B cell differentiation to plasma cells is warranted.

The role of neuraminidase 1 (NEU1) in cytokine release by primary mouse mesangial cells and disease outcomes in murine lupus nephritis

The importance of altered glycosphingolipid (GSL) metabolism is increasingly gaining attention as a characteristic of multiple chronic kidney diseases. Previously, we reported elevated levels of GSLs and neuraminidase (NEU) enzyme activity/expression in the urine or kidney of lupus patients and lupus-prone mice, and demonstrated NEU activity mediates the production of cytokines by lupus-prone mouse primary mesangial cells. This mediation occurs in part through TLR4 and p38/ERK MAPK signalling in response to lipopolysaccharide (LPS) and lupus serum (LS). However, the precise role of NEU1, the most abundant NEU in the kidney, is incompletely known. In this study, we investigated the effect of genetically reduced Neu1 levels in vitro and in vivo. Mesangial cells from non-autoimmune prone Neu1+/- C57BL/6 mice had significantly reduced NEU activity, cytokine expression and cytokine secretion in response to LS and LPS, thereby suggesting reducing Neu1 expression may reduce the inflammatory response in lupus nephritis. Disease was assessed in female B6.SLE1/2/3 lupus-prone mice with genetically reduced levels (Neu1+/-) or wild-type levels (Neu1+/+) of Neu1 from 28 to 44 weeks of age along with aged-matched C57BL/6 controls. Renal disease was unexpectedly mild in all B6.SLE1/2/3 mice despite evidence of systemic disease. B6.SLE1/2/3 Neu1+/- mice exhibited significantly reduced levels of renal NEU1 expression and changes in renal α-2,6 linked sialylated N-glycans compared to the Neu1+/+ or healthy C57BL/6 mice, but measures of renal and systemic disease were similar between the B6.SLE1/2/3 Neu1+/+ and Neu1+/- mice. We conclude that NEU1 is the NEU largely responsible for mediating cytokine release by mesangial cells, at least in vitro, but may not be involved in modulating renal GSL levels in vivo or impact onset of nephritis in lupus-prone mice. However, the effect of reduced NEU1 levels on disease may not be appreciated in the mild disease expression in our colony of B6.SLE1/2/3 mice. The impact of the altered renal sialylated N-glycan levels and potential role of NEU1 with respect to established nephritis (late disease) in lupus-prone mice bears further investigation.

B Cell Aberrance in Lupus: the Ringleader and the Solution

Systemic lupus erythematosus (SLE) is a prototypical autoimmune disease with high heterogeneity but the common characterization of numerous autoantibodies and systemic inflammation which lead to the damage of multiple organs. Aberrance of B cells plays a pivotal role in the immunopathogenesis of SLE via both antibody-dependent and antibody-independent manners. Escape of autoreactive B cells from the central and peripheral tolerance checkpoints, over-activation of B cells and their excessive cytokines release which drive T cells and dendritic cells stimulation, and dysregulated surface molecules, as well as intracellular signal pathways involved in B cell biology, are all contributing to B cell aberrance and participating in the pathogenesis of SLE. Based on that rationale, targeting aberrance of B cells and relevant molecules and pathways is expected to be a promising strategy for lupus control. Multiple approaches targeting B cells through different mechanisms have been attempted, including B-cell depletion via monoclonal antibodies against B-cell-specific molecules, blockade of B-cell survival and activation factors, suppressing T-B crosstalk by interrupting costimulatory molecules and inhibiting intracellular activation signaling cascade by targeting pathway molecules in B cells. Though most attempts ended in failure, the efficacy of B-cell targeting has been encouraged by the FDA approval of belimumab that blocks B cell-activating factor (BAFF) and the recommended use of anti-CD20 as a remedial therapy in refractory lupus. Still, quantities of clinical trials targeting B cells or relevant molecules are ongoing and some of them have displayed promising preliminary results. Additionally, advances in multi-omics studies help deepen our understandings of B cell biology in lupus and may promote the discovery of novel potential therapeutic targets. The combination of real-world data with basic research achievements may pave the road to conquering lupus.

The role of neuraminidase in TLR4-MAPK signalling and the release of cytokines by lupus serum-stimulated mesangial cells

Previously, we demonstrated neuraminidase (NEU) activity or NEU1 expression, specifically, is increased in the kidneys of lupus mice and urine of human patients with nephritis. Additionally, NEU activity mediates IL-6 secretion from lupus-prone MRL/lpr primary mouse mesangial cells (MCs) in response to an IgG mimic. IL-6 mediates glomerular inflammation and promotes tissue damage in patients and mouse strains with lupus nephritis. This study further elucidates the mechanisms by which NEU activity and NEU1 specifically mediates the release of IL-6 and other cytokines from lupus-prone MCs. We demonstrate significantly increased release of multiple cytokines and NEU activity in MRL/lpr MCs in response to serum from MRL/lpr mice (lupus serum). Inhibiting NEU activity significantly reduced secretion of three of those cytokines: IL-6, GM-CSF and MIP1α. Message levels of Il-6 and Gm-csf were also increased in response to lupus serum and reduced when NEU activity was inhibited. Neutralizing antibodies to cell-surface receptors and MAPK inhibitors in lupus serum- or LPS-stimulated MCs indicate TLR4 and p38 or ERK MAP kinase signalling play key roles in the NEU-mediated secretion of IL-6. Significantly reduced IL-6 release was observed in C57BL/6 (B6) Neu1+/+ primary MCs compared with wild-type (Neu1+/+) B6 MCs in response to lupus serum. Additional results show inhibiting NEU activity significantly increases sialic acid-containing N-glycan levels. Together, our novel observations support a role for NEU activity, and specifically NEU1, in mediating release of IL-6 from lupus-prone MCs in response to lupus serum through a TLR4-p38/ERK MAPK signalling pathway that likely includes desialylation of glycoproteins.

Systemic lupus erythematosus is associated with impaired autophagic degradation via interleukin-6 in macrophages

Systemic lupus erythematosus (SLE) is an autoimmune disease associated with dysregulated interleukin (IL)-6 and autophagy. Although such disturbances are increasingly recognized in patients with SLE and animal models of the disease, little is known about the specific role of IL-6 and autophagy in SLE macrophages. Here, we investigated alterations in the IL-6 axis and autophagy in macrophages derived from patients with SLE and determined whether IL-6 modulates autophagy using human macrophage models. Serum IL-6 detected by ELISA was higher in SLE patients (n = 19) than in normal controls (n = 19, p < 0.001). Levels of the IL-6 receptor (IL-6R) and autophagic markers LC3B and p62 in SLE and normal macrophages were assessed by real-time PCR, western blotting, and immunofluorescence. Compared with normal macrophages, SLE macrophages not only overexpressed IL-6Rs but also exhibited impaired autophagic degradation as evidenced by elevated levels of LC3B and p62. In vitro analyses using macrophage models revealed that prolonged exposure to exogenous recombinant human IL-6 induced a marked impairment of autophagic degradation indicated by elevated levels of LC3B and p62 in both primary macrophages and transformed macrophages. Pretreatment with tocilizumab, a humanized anti-IL-6R monoclonal antibody, restored autophagic degradation and reversed p62 accumulation in a paracrine manner in macrophages. These findings demonstrate that SLE involves IL-6-induced impairment of autophagic degradation through augmentation of IL-6R in human macrophages.

Kras-Deficient T Cells Attenuate Graft-versus-Host Disease but Retain Graft-versus-Leukemia Activity

Acute graft-versus-host disease (aGVHD) is one major serious complication that is induced by alloreactive donor T cells recognizing host Ags and limits the success of allogeneic hematopoietic stem cell transplantation. In the current studies, we identified a critical role of Kras in regulating alloreactive T cell function during aGVHD. Kras deletion in donor T cells dramatically reduced aGVHD mortality and severity in an MHC-mismatched allogeneic hematopoietic stem cell transplantation mouse model but largely maintained the antitumor capacity. Kras-deficient CD4 and CD8 T cells exhibited impaired TCR-induced activation of the ERK pathway. Kras deficiency altered TCR-induced gene expression profiles, including the reduced expression of various inflammatory cytokines and chemokines. Moreover, Kras deficiency inhibited IL-6-mediated Th17 cell differentiation and impaired IL-6-induced ERK activation and gene expression in CD4 T cells. These findings support Kras as a novel and effective therapeutic target for aGVHD.

The novel role of Hippo-YAP/TAZ in immunity at the mammalian maternal-fetal interface: Opportunities, challenges

The Hippo-Yes-associated protein (YAP)/transcriptional co-activator with PDZ-binding motif (TAZ), originally identified as a regulator of tissue generation and tumorigenesis, has been proven to have a pivotal position in immunity. Its multi-faceted roles in regulating immunity cover both intrinsic mechanism of immune cells and the crosstalk with non-immune cells. Survival of the allogeneic embryo in the maternal uterine environment depends on immune tolerance, supported by the highly orchestrated cooperation between decidual immune cells, decidual stromal cells and trophoblasts at the maternal-fetal interface. The abnormal maternal-fetal dialogue is believed to be associated with adverse pregnancy outcomes such as spontaneous pregnancy loss. Recent breakthroughs shed light on the how the Hippo-YAP/TAZ manipulate the decidualization and trophoblast invasion, while further research is needed to integrate and reconcile existing findings of the Hippo-YAP/TAZ in immunity and to extend them at the context of pregnancy. In this review, we summarized the Hippo-YAP/TAZ pathways, detailed the effects of YAP/TAZ on immune cells, and discussed the role of YAP/TAZ at the maternal-fetal interface and the potential of YAP/TAZ on immunity regulation at the context of pregnancy. Given the remarkable effect of therapeutic intervention of YAP/TAZ in cancer and autoimmune diseases, it is worthy to explore the response to YAP/TAZ inhibition in the maternal-fetal immunity. This may provide a new valuable target for therapy of pregnancy loss, or potentially other pregnancy complications.

Molecular pathobiology of scleritis and its therapeutic implications

Scleritis and other autoimmune diseases are characterized by an imbalance in the levels of pro-inflammatory and anti-inflammatory molecules with the balance tilted more towards the former due to the failure of recognition of self. The triggering of inflammatory process could be ascribed to the presence of cytoplasmic DNA/chromatin that leads to activation of cytosolic DNA-sensing cGAS-STING (cyclic GMP-AMP synthase linked to stimulator of interferon genes) pathway and enhanced expression of NF-κB that results in an increase in the production of pro-inflammatory bioactive lipids. Bioactive lipids gamma-linolenic acid (GLA), dihomo-GLA (DGLA), prostaglandin E1 (PGE1), prostacyclin (PGI2) and lipoxin A4, resolvins, protectins and maresins have anti-inflammatory actions, bind to DNA to render it non-antigenic and are decreased in autoimmune diseases. These results suggest that efforts designed to enhance the production of anti-inflammatory bioactive lipids may form a new approach to autoimmune diseases. Local injection or infusion of lipoxins, resolvins, protectins and maresins or their precursors such as arachidonic acid may be exploited in the prevention and management of autoimmune diseases including scleritis, uveitis and lupus/rheumatoid arthritis.

Serum interleukin-6 level is correlated with the disease activity of systemic lupus erythematosus: a meta-analysis

Interleukin-6 (IL-6) plays a crucial role in systemic autoimmunity and pathologic inflammation. Numerous studies have explored serum IL-6 levels in systemic lupus erythematosus (SLE) and their correlation with disease activity. Here, we performed a meta-analysis to quantitatively assess the correlation between the serum IL-6 levels and SLE activity. The PubMed and EMBASE databases were thoroughly searched for relevant studies up to September 2019. Standardized mean differences (SMDs) with 95% confidence intervals (95% CIs) were used to describe the differences between serum IL-6 levels in SLE patients and healthy controls and between those in active SLE patients and inactive SLE patients. The correlation between the serum IL-6 levels and disease activity was evaluated using Fisher's z values. A total of 24 studies involving 1817 SLE patients and 874 healthy controls were included in this meta-analysis. Serum IL-6 levels were significantly higher in SLE patients than in the healthy controls (pooled SMD: 2.12, 95% CI: 1.21-3.03, Active SLE patients had higher serum IL-6 levels than inactive SLE patients (pooled SMD: 2.12, 95% CI: 1.21-3.03). Furthermore, the pooled Fisher's z values (pooled Fisher's z=0.36, 95% CI: 0.26-0.46, p<0.01) showed that there was a positive correlation between the serum IL-6 levels and SLE activity. This study suggested that serum IL-6 levels were higher in patients with SLE than in healthy controls, and they were positively correlated with disease activity when Systemic Lupus Erythematosus Disease Activity Index>4 was defined as active SLE. More homogeneous studies with large sample sizes are warranted to confirm our findings due to several limitations in our meta-analysis.

B Cell Abnormalities in Systemic Lupus Erythematosus and Lupus Nephritis-Role in Pathogenesis and Effect of Immunosuppressive Treatments

Abnormalities in B cells play pivotal roles in the pathogenesis of systemic lupus erythematosus (SLE) and lupus nephritis (LN). Breach in central and peripheral tolerance mechanisms generates autoreactive B cells which contribute to the pathogenesis of SLE and LN. Dysregulation of B cell transcription factors, cytokines and B cell-T cell interaction can result in aberrant B cell maturation and autoantibody production. These immunological abnormalities also lead to perturbations in circulating and infiltrating B cells in SLE and LN patients. Conventional and novel immunosuppressive medications confer differential effects on B cells which have important clinical implications. While cyclophosphamide and mycophenolate mofetil (MMF) showed comparable clinical efficacy in active LN, MMF induction was associated with earlier reduction in circulating plasmablasts and plasma cells. Accumulating evidence suggests that MMF maintenance is associated with lower risk of disease relapse than azathioprine, which may be explained by its more potent and selective suppression of B cell proliferation. Novel therapeutic approaches targeting the B cell repertoire include B cell depletion with monoclonal antibodies binding to cell surface markers, inhibition of B cell cytokines, and modulation of costimulatory signals in B cell-T cell interaction. These biologics, despite showing improvements in serological parameters and proteinuria, did not achieve primary endpoints when used as add-on therapy to standard treatments in active LN patients. Other emerging treatments such as calcineurin inhibitors, mammalian target of rapamycin inhibitors and proteasome inhibitors also show distinct inhibitory effects on the B cell repertoire. Advancement in the knowledge on B cell biology has fueled the development of new therapeutic strategies in SLE and LN. Modification in background treatments, study endpoints and selective recruitment of subjects showing aberrant B cells or its signaling pathways when designing future clinical trials may better elucidate the roles of these novel therapies for SLE and LN patients.

B cells targeting therapy in the management of systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease which affects the majority of organs and systems. Traditional therapies do not lead to complete remission of disease but only relieve symptoms and inflammation. B cells are the most important effector cell types in the pathogenesis of SLE. Therefore, therapies targeting B cells and their related cytokines are a very important milestone for SLE treatment. Several biologics that modulate B cells, either depleting B cells or blocking B cell functions, have been developed and evaluated in clinical trials. Belimumab, a fully humanized monoclonal antibody that specifically binds B cells activating factor (BAFF), was the first of these agents approved for SLE treatment. In this review, we explore the currently available evidence in B cell targeted therapies in SLE including agents that target B cell surface antigens (CD19, CD20, CD22), B cell survival factors (BAFF and a proliferation-inducing ligand, APRIL), cytokines (interleukin-1 and type 1 interferons) and co-stimulatory molecules (CD40 ligand). We highlighted the mechanisms of action and the individual characteristics of these biologics, and present an update on the clinical trials that have evaluated their efficacy and safety. Finally, we describe some of the emerging and promising therapies for SLE treatment.

Interactions among glomerulus infiltrating macrophages and intrinsic cells via cytokines in chronic lupus glomerulonephritis

Inflammation plays a key role in the pathogenesis of lupus nephritis (LN) and inflammatory cytokines within the glomeruli are critical in this process. However, little information is available for the identities of the cell types that are primarily responsible for the production and function of the various cytokines. We have devised a novel method to visualize cytokine signals in the kidney by confocal microscopy and found that cytokine production within the glomerulus is cell type-specific and under translational control. In the lupus-prone NZM2328 mice with chronic glomerulonephritis, IL-6, IL-1β, and TNF-α in the glomerulus were produced predominantly by mesangial cells, podocytes, and glomerulus-infiltrating blood-derived macrophages, respectively. Microarray and RNASeq analyses showed that these cells expressed the receptors for these cytokines. Together the 3 cell types form a cytokine circuit in amplifying cytokine responses in LN. The intrinsic cells and infiltrating macrophages also produced other cytokines including M-CSF, SCF, and IL-34 that constituted within the enclosed glomerular space the soluble effector milieu which may mediate cellular damage and proliferation, and cytokine transcriptional and translation regulation. IL-10 and IL-1β were translationally regulated in the glomeruli in the intact kidney in a cell type-specific manner. The production of these 2 cytokines by infiltrating macrophages was undetectable in a visualization system for in situ protein accumulation despite high mRNA expression levels. However, these macrophages in isolated glomeruli which are released from Bowman's capsules produced large amounts of IL-10 and IL-1β. These data reveal the complexity of cytokine regulation, production, and function in the glomerulus and provide a model in which cytokine blocking may be beneficial in LN treatment.

DNA methylation was involved in total glucosides of paeony regulating ERα for the treatment of female systemic lupus erythematosus mice

Total glucosides of paeony (TGP) is a bioactive compound extracted from paeony roots and has been used in therapy for autoimmune diseases. However the molecular mechanism of TGP in the therapy of autoimmune diseases remains unclear. ERα has a pro-inflammatory role in SLE disease. In this study, we found that TGP treatment significantly decreased the expression of ERα by up-regulating ERα promoter methylation levels. Further investigation revealed that treatment with TGP increased the expression of DNMT in lupus mice. We also used DNA methyltransferase inhibitors to verify whether DNA methylation was involved in these process. HE staining results showed that TGP can reduce renal injury in SLE mice. Moreover, cytokines including IFN-γ, IL6 and IL12 expression and dsDNA levels in serum were inhibited by TGP treatment. These findings indicate that TGP inhibits autoimmunity in SLE mice possibly by downregulate ERα expression, which may in turn be due to its ability to regulate the methylation status of the ERα promoter.

Vitamin D supplementation ameliorates arthritis but does not alleviates renal injury in pristane-induced lupus model

Systemic lupus erythematosus (SLE) is a multifactorial and autoimmune inflammatory disease with pleomorphic clinical manifestations involving different organs and tissues. The study of different murine models has provided a better understanding of these autoimmune phenomena. Pristane-induced lupus represents a suitable model to study factors that could influence the induction and/or progression of SLE, including genetic factors. The objective of the present study was to evaluate the development and evolution of SLE after vitamin D supplementation in PIL model. Here, we evaluated the effects of vitamin D supplementation in model of pristane-induced SLE in female BALB/c mice. The animals were randomly divided into three groups: control group (CO), pristane-induced lupus group (PIL) and pristane-induced lupus group plus vitamin D (VD). Lupus was induced in PIL and VD groups using pristane. PIL group showed arthritis and kidney injury, characterized by increased proteinuria, glomerular mesangial expansion and inflammation. Moreover, PIL model showed increased levels of IL-6, TNF-α and IFN-γ in serum. We observed that treatment with vitamin D improved arthritis through reduced of incidence and arthritis clinical score and edema, but does not influenced renal injury. Treatment with vitamin D was not able to reduce proteinuria levels, decrease mesangial hypercellularity or IgG and IgM deposition in the kidney. Vitamin D supplementation did not alter IL-6, TNF-α, IL-2 and IL-4, but reduce IFN-γ. These results support that the role of vitamin D may be different depending on acting site, what could explain different responses according clinical phenotype. Therefore, further investigations of vitamin D are needed to explore the supplement dosage, timing, and the molecular basis in SLE.

Local miscommunications between glomerular cells as potential therapeutic targets for crescentic glomerulonephritides

Necrotizing and crescentic rapidly progressive glomerulonephritis or crescentic glomerulonephritis is one of the severest forms of acquired glomerular diseases with significant mortality. Risk of end-stage renal failure at 5 years is near 30%, with a number of patients developing chronic kidney disease. Currently, autoimmune crescentic glomerulonephritides are treated with broad-spectrum immunosuppression inducing remission of the injury in the majority of patients. However, treatment is associated with significant side effects and by the time remission is achieved the majority of patients have developed renal tissue damage and significant impairment of their kidney function with a steep slope of deterioration within the first weeks following initiation of immunosuppression. It is therefore important to develop complementary strategies that would be immediately active on the common process of destructive epithelial processes. We have worked to identify the major cellular pathways contributing to glomerular destruction in this context by a systematic comparison of patient tissues and experimental models. Our studies demonstrate the pivotal role of local intra- and intercellular communications in orchestrating the global glomerular tolerance to a severe rapidly progressive glomerulonephritis model with excellent anatomoclinical correlative expressions in kidney biopsies of individuals diagnosed with crescentic glomerulonephritis, irrespectively of the causal immune disorder. We hope that such approaches deciphering mechanisms of cellular adaptation that underlie kidney damage control in response to vasculitides, integrating both stress and damage responses, will delineate novel complementary therapies.

TARGETING TARGETED TREATMENT FOR IMMUNE AND NON-IMMUNE KIDNEY DISEASES

We have found that calcium calmodulin kinase IV is increased in T cells, podocytes, and mesangial cells from patients with systemic lupus erythematosus, as well as in lupus-prone mice, podocytes of patients with focal segmental glomerulosclerosis, and in mice injected with doxorubicin. We showed that this accounts for aberrant T cell function and glomerular damage. Using nanoparticles (nlg) loaded with a small drug inhibitor of calcium calmodulin kinase IV and tagged with antibodies directed to CD4 we have been able to show inhibition of autoimmunity and lupus nephritis. Also, using nlg tagged with antibodies to nephrin, we showed suppression of nephritis in lupus-prone mice and of glomerular damage in mice exposed to doxorubicin. We propose the development of approaches to deliver drugs to cells in a targeted and precise manner.

Calcium/Calmodulin Kinase IV Controls the Function of Both T Cells and Kidney Resident Cells

Calcium calmodulin kinase IV (CaMK4) regulates multiple processes that significantly contribute to the lupus-related pathology by controlling the production of IL-2 and IL-17 by T cells, the proliferation of mesangial cells, and the function and structure of podocytes. CaMK4 is also upregulated in podocytes from patients with focal segmental glomerulosclerosis (FSGS). In both immune and non-immune podocytopathies, CaMK4 disrupts the structure and function of podocytes. In lupus-prone mice, targeted delivery of a CaMK4 inhibitor to CD4⁺ T cells suppresses both autoimmunity and the development of nephritis. Targeted delivery though to podocytes averts the deposition of immune complexes without affecting autoimmunity in lupus-prone mice and averts pathology induced by adriamycin in normal mice. Therefore, targeted delivery of a CaMK4 inhibitor to podocytes holds high therapeutic promise for both immune (lupus nephritis) and non-immune (FSGS) podocytopathies.

Neuraminidase activity mediates IL-6 production by activated lupus-prone mesangial cells

The development of nephritis is a leading cause of morbidity and mortality in lupus patients. Although the general pathophysiological progression of lupus nephritis is known, the molecular mediators and mechanisms are incompletely understood. Previously, we demonstrated that the glycosphingolipid (GSL) catabolic pathway is elevated in the kidneys of MRL/lpr lupus mice and human lupus patients with nephritis. Specifically, the activity of neuraminidase (NEU) and expression of Neu1, an enzyme in the GSL catabolic pathway is significantly increased. To better understand the role and mechanisms by which this pathway contributes to the progression of LN, we analyzed the expression and effects of NEU activity on the function of MRL/lpr lupus-prone mesangial cells (MCs). We demonstrate that NEU1 and NEU3 promote IL-6 production in MES13 MCs. Neu1 expression, NEU activity, and IL-6 production are significantly increased in stimulated primary MRL/lpr lupus-prone MCs, and blocking NEU activity inhibits IL-6 production. NEU1 and NEU3 expression overlaps IgG deposits in MCs in vitro and in renal sections from nephritic MRL/lpr mice. Together, our results suggest that NEU activity mediates IL-6 production in lupus-prone MCs possibly through an IgG-receptor complex signaling pathway.

New Treatments for Systemic Lupus Erythematosus on the Horizon: Targeting Plasmacytoid Dendritic Cells to Inhibit Cytokine Production

Patients with systemic lupus erythematosus (SLE) often have elevated levels of type I interferon (IFN, particularly IFNα), a cytokine that can drive many of the symptoms associated with this autoimmune disorder. Additionally, the presence of autoantibody-secreting plasma cells contributes to the systemic inflammation observed in SLE and IFNα supports the survival of these cells. Current therapies for SLE are limited to broad immunosuppression or B cell-targeting antibody-mediated depletion strategies, which do not eliminate autoantibody-secreting plasma cells. Recent clinical trials testing the efficacy of IFNα neutralization in SLE have delivered disappointing results, with primary endpoints not being met or with minimal improvements, while studies evaluating antibody therapy targeting the type I IFN receptor was more successful and is currently being tested in phase III clinical studies. As many studies have supported the idea that plasmacytoid dendritic cells (pDCs) are the main source of IFNα in SLE, specifically targeting pDCs in SLE represents a new therapeutic option. Murine models suggest pDC ablation effectively ameliorates or reduces lupus-like disease development in spontaneous models of lupus and pre-clinical and phase I clinical trials support the safety of such a therapy in humans. Here we review animal studies and the current status of clinical trials targeting IFNα, type I interferon receptor and pDCs in SLE.

From mechanism to therapies in systemic lupus erythematosus

PURPOSE OF REVIEW

Systemic lupus erythematosus (SLE) is a disabling and deadly disease. Development of novel therapies for SLE has historically been limited by incomplete understanding of immune dysregulation. Recent advances in lupus pathogenesis, however, have led to the adoption or development of new therapeutics, including the first Food and Drug Administration-approved drug in 50 years.

RECENT FINDINGS

Multiple cytokines (interferon, B lymphocyte stimulator, IL-6, and IL-17), signaling pathways (Bruton's Tyrosine Kinase, Janus kinase/signal transducer and activator of transcription), and immune cells are dysregulated in SLE. In this review, we cover seminal discoveries that demonstrate how this dysregulation is integral to SLE pathogenesis and the novel therapeutics currently under development or in clinical trials. In addition, early work suggests metabolic derangements are another target for disease modification. Finally, molecular profiling has led to improved patient stratification in the heterogeneous SLE population, which may improve clinical trial outcomes and therapeutic selection.

SUMMARY

Recent advances in the treatment of SLE have directly resulted from improved understanding of this complicated disease. Rheumatologists may have a variety of novel agents and more precise targeting of select lupus populations in the coming years.

A Multicenter, Randomized, Double-Blind, Placebo-Controlled Study to Evaluate the Efficacy and Safety of Treatment With Sirukumab (CNTO 136) in Patients With Active Lupus Nephritis

Objective

To assess the efficacy and safety of sirukumab, an anti–interleukin‐6 monoclonal antibody, for the treatment of patients with active lupus nephritis (LN).

Methods

Patients with class III or class IV LN (as determined by renal biopsy within 14 months of randomization) who had persistent proteinuria (>0.5 gm/day) despite receiving immunosuppressive therapy and who were being treated with stable doses of a renin‐angiotensin system blocker were randomized (5:1) to receive treatment with sirukumab at a dose of 10 mg/kg intravenously (n = 21) or placebo (n = 4) every 4 weeks through week 24. The primary end point was the percent reduction in proteinuria (measured as the protein‐to‐creatinine [P:C] ratio in a 12‐hour urine collection) from baseline to week 24.

Results

Twenty‐five patients were enrolled, of whom 19 (76.0%) completed treatment through week 24 and 6 (24.0%) discontinued the study agent early, with 5 of the 6 discontinuing due to adverse events. At week 24, the median percent change in proteinuria from baseline to week 24 in sirukumab‐treated patients was 0.0% (95% confidence interval −61.8, 39.6). In contrast, the 4 placebo‐treated patients showed an increase in proteinuria (median percent reduction −43.3%) at week 24. Of note, a subset of 5 sirukumab‐treated patients had ≥50% improvement in their P:C ratio through week 28. In the sirukumab group, 47.6% of patients experienced ≥1 serious adverse event through week 40; most were infection‐related. No deaths or malignancies occurred. No serious adverse events were observed in the 4 placebo‐treated patients.

Conclusion

This proof‐of‐concept study did not demonstrate the anticipated efficacy nor did it demonstrate an acceptable safety profile for sirukumab treatment in this population of patients with active LN receiving concomitant immunosuppressive treatment.

Recent advances in the understanding of renal inflammation and fibrosis in lupus nephritis

Lupus nephritis is a potentially reversible cause of severe acute kidney injury and is an important cause of end-stage renal failure in Asians and patients of African or Hispanic descent. It is characterized by aberrant exaggerated innate and adaptive immune responses, autoantibody production and their deposition in the kidney parenchyma, triggering complement activation, activation and proliferation of resident renal cells, and expression of pro-inflammatory and chemotactic molecules leading to the influx of inflammatory cells, all of which culminate in destruction of normal nephrons and their replacement by fibrous tissue. Anti-double-stranded DNA (anti-dsDNA) antibody level correlates with disease activity in most patients. There is evidence that apart from mediating pathogenic processes through the formation of immune complexes, pathogenic anti-dsDNA antibodies can bind to resident renal cells and induce downstream pro-apoptotic, pro-inflammatory, or pro-fibrotic processes or a combination of these. Recent data also highlight the critical role of macrophages in acute and chronic kidney injury. Though clinically effective, current treatments for lupus nephritis encompass non-specific immunosuppression and the anti-inflammatory action of high-dose corticosteroids. The clinical and histological impact of novel biologics targeting pro-inflammatory molecules remains to be investigated. Insight into the underlying mechanisms that induce inflammatory and fibrotic processes in the kidney of lupus nephritis could present opportunities for more specific novel treatment options to improve clinical outcomes while minimizing off-target untoward effects. This review discusses recent advances in the understanding of pathogenic mechanisms leading to inflammation and fibrosis of the kidney in lupus nephritis in the context of established standard-of-care and emerging therapies.

IL-6 signaling in diabetic nephropathy: From pathophysiology to therapeutic perspectives

Diabetic nephropathy (DN) is a leading cause of chronic kidney disease (CKD). Interleukin-6 (IL-6) signaling participates in inflammation responses central to the progression of DN. Current evidence suggests that these IL-6 responses are mediated via gp130-STAT3 dependent mechanisms which, on one hand, trigger globally the transition from innate to adaptive immune response, and on the other hand act locally for tissue remodeling and immune cell infiltration. In diabetic conditions the role of IL-6 is not well elucidated. Both IL-6 classical signaling pathway via receptor IL-6R (IL-6R) and IL-6 trans-signaling pathway via soluble IL-6R (sIL-6R) were shown to participate in the pathogenesis and progression of DN, and IL-6 appears to influence renal cells also in an autocrine manner. To date, evidence is limited. The goal of this review is to provide an overview of our current understanding on the role of IL-6 signaling in DN and to delineate challenges for future research. Putative sequential events related to IL-6 secretion by different cell populations in diabetic conditions are outlined. Further, we discuss potential applications of anti-IL-6 therapy in the context of DN.

Toll-like receptor-mediated immune responses in intestinal macrophages; implications for mucosal immunity and autoimmune diseases

Monocytes are precursors of macrophages and key players during inflammation and pathogen challenge in the periphery, whereas intestinal resident macrophages act as innate effector cells to engulf and clear bacteria, secrete cytokines, and maintain intestinal immunity and homeostasis. However, perturbation of toll-like receptor signaling pathway in intestinal macrophages has been associated with tolerance breakdown in autoimmune diseases. In the present review, we have summarized and discussed the role of toll-like receptor signals in human intestinal macrophages, and the role of human intestinal macrophages in keeping human intestinal immunity, homeostasis, and autoimmune diseases.

Spotlight on sirukumab for the treatment of rheumatoid arthritis: the evidence to date

Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory disease primarily affecting synovial joints and is characterized by persistent high-grade systemic inflammation. Proinflammatory cytokines, particularly interleukin-6 (IL-6), are of crucial importance in the pathogenesis of the disease, driving both joint inflammation and extra-articular comorbidities. Tocilizumab, a humanized IL-6 receptor-inhibiting monoclonal antibody, has been the first, and, to date, the only, IL-6 inhibitor approved for the treatment of RA. Many studies have demonstrated the potency and effectiveness of tocilizumab in controlling disease activity and radiological progression of RA. These successful results have encouraged the development of novel IL-6 inhibitors, among which a promising agent is sirukumab (SRK), a human anti-IL-6 monoclonal antibody currently under evaluation in Phase II/III studies in patients with RA, systemic lupus erythematosus, giant-cell arteritis, and major depressive disorder. The evidence to date indicates SRK as an effective and well-tolerated new therapeutic tool for patients with active RA, with some preliminary data suggesting a specific beneficial impact on relevant systemic complications associated with the disease, such as depression and cardiovascular disease. Conversely, although pathophysiological considerations make plausible the hypothesis that IL-6 blockade with SRK may also be beneficial in the treatment of many diseases other than RA (either autoimmune or not), available clinical data in patients with systemic lupus erythematosus do not seem to support this view, also giving rise to potentially relevant concerns about drug safety. If large Phase III clinical trials currently in progress in patients with RA confirm the efficacy and tolerability of SRK, then in the long term, this drug could, in the near future, occupy a place in the treatment of the disease, potentially also opening the doors to a more extended use of SRK in a wide range of disorders in which IL-6 plays a key pathogenic role.

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.

Brief Report: Interleukin-38 Exerts Antiinflammatory Functions and Is Associated With Disease Activity in Systemic Lupus Erythematosus

OBJECTIVE

Knowledge of interleukin-38 (IL-38), formerly IL-1 family member 10, is sparse, but Il1f10 polymorphisms are associated with inflammatory diseases, and recombinant IL-38 inhibits inflammatory responses similar to those reported in the context of systemic lupus erythematosus (SLE). We undertook this study to explore the function of endogenous IL-38 in human peripheral blood mononuclear cells (PBMCs) as well as its abundance in serum in a well-characterized cohort of SLE patients.

METHODS

Serum IL-38 and IL-10 levels were quantified by enzyme-linked immunosorbent assay in 142 SLE patients at ≤3 consecutive visits and in 28 healthy volunteers. To assess IL-38 function, we silenced IL-38 in PBMCs from healthy donors using IL-38 small interfering RNA (siRNA).

RESULTS

IL-38 (63-5,928 pg/ml) was detectable in 16% of 372 serum samples. IL-38 abundance was significantly higher in samples from SLE patients than in samples from healthy controls (P = 0.004) and 11-fold higher in patients with active disease (SLE Disease Activity Index 2000 [SLEDAI-2K] score of ≥4) than in those with inactive disease (SLEDAI-2K score of <4) (P = 0.044). Importantly, IL-38 detection was associated with increased risk of renal lupus (relative risk [RR] 1.6, P = 0.027) and central nervous system lupus (RR 2.3, P = 0.034), and detectable baseline IL-38 entailed a 1.6-fold increased risk of subsequently meeting criteria for persistently active disease (P = 0.0097). Longitudinal time-adjusted mean IL-38 concentration was also 6-fold higher in patients with persistently active disease than in those without (P = 0.023). Remarkably, PBMCs treated with IL-38 siRNA produced up to 28-fold more of the proinflammatory mediators IL-6, CCL2, and APRIL than did control siRNA-transfected cells upon stimulation with Toll-like receptor agonists. Similarly, in SLE patients, the antiinflammatory cytokine IL-10 was 5-fold more abundant when IL-38 was detectable.

CONCLUSION

This is the first study of the function of endogenous IL-38, and the data suggest that IL-38 may be protective in SLE. A strong association between IL-38 and SLE severity suggests that IL-38 expression is driven by processes linked to SLE pathogenesis. Exploitation of the regulatory effects of IL-38 may represent a promising therapeutic strategy in SLE.

Current and emerging treatment options in the management of lupus

Systemic lupus erythematosus (SLE) is a complex autoimmune disease with variable clinical manifestations. While the clearest guidelines for the treatment of SLE exist in the context of lupus nephritis, patients with other lupus manifestations such as neuropsychiatric, hematologic, musculoskeletal, and severe cutaneous lupus frequently require immunosuppression and/or biologic therapy. Conventional immunosuppressive agents such as mycophenolate mofetil, azathioprine, and cyclophosphamide are widely used in the management of SLE with current more rationalized treatment regimens optimizing the use of these agents while minimizing potential toxicity. The advent of biologic therapies has advanced the treatment of SLE particularly in patients with refractory disease. The CD20 monoclonal antibody rituximab and the anti-BLyS agent belimumab are now widely in use in clinical practice. Several other biologic agents are in ongoing clinical trials. While immunosuppressive and biologic agents are the foundation of inflammatory disease control in SLE, the importance of managing comorbidities such as cardiovascular risk factors, bone health, and minimizing susceptibility to infection should not be neglected.

Progress with the use of monoclonal antibodies for the treatment of systemic lupus erythematosus

In recent years, significant progress has been made in the use of monoclonal antibodies in the treatment of systemic lupus erythematosus (SLE). Advances in our understanding of the complexity of SLE immunopathogenesis have led to the testing of several biologic agents in clinical trials. Monoclonal therapies currently emerging or under development include B-cell depletion therapies, agents targeting B-cell survival factors, blockade of T-cell co-stimulation and anticytokine therapies. Issues remain, however, regarding clinical trial design and outcome measures in SLE which need to be addressed to optimize translation of these promising therapies into clinical practice.

Necroinflammation in Kidney Disease

The bidirectional causality between kidney injury and inflammation remains an area of unexpected discoveries. The last decade unraveled the molecular mechanisms of sterile inflammation, which established danger signaling via pattern recognition receptors as a new concept of kidney injury-related inflammation. In contrast, renal cell necrosis remained considered a passive process executed either by the complement-related membrane attack complex, exotoxins, or cytotoxic T cells. Accumulating data now suggest that renal cell necrosis is a genetically determined and regulated process involving specific outside-in signaling pathways. These findings support a unifying theory in which kidney injury and inflammation are reciprocally enhanced in an autoamplification loop, referred to here as necroinflammation. This integrated concept is of potential clinical importance because it offers numerous innovative molecular targets for limiting kidney injury by blocking cell death, inflammation, or both. Here, the contribution of necroinflammation to AKI is discussed in thrombotic microangiopathies, necrotizing and crescentic GN, acute tubular necrosis, and infective pyelonephritis or sepsis. Potential new avenues are further discussed for abrogating necroinflammation-related kidney injury, and questions and strategies are listed for further exploration in this evolving field.

Human embryonic stem cell-derived mesenchymal cells preserve kidney function and extend lifespan in NZB/W F1 mouse model of lupus nephritis

Adult tissue-derived mesenchymal stromal cells (MSCs) are showing promise in clinical trials for systemic lupus erythematosus (SLE). However, the inability to manufacture large quantities of functional cells from a single donor as well as donor-dependent variability in quality limits their clinical utility. Human embryonic stem cell (hESC)-derived MSCs are an alternative to adult MSCs that can circumvent issues regarding scalability and consistent quality due to their derivation from a renewable starting material. Here, we show that hESC-MSCs prevent the progression of fatal lupus nephritis (LN) in NZB/W F1 (BWF1) mice. Treatment led to statistically significant reductions in proteinuria and serum creatinine and preserved renal architecture. Specifically, hESC-MSC treatment prevented disease-associated interstitial inflammation, protein cast deposition, and infiltration of CD3⁺ lymphocytes in the kidneys. This therapy also led to significant reductions in serum levels of tumor necrosis factor alpha (TNFα) and interleukin 6 (IL-6), two inflammatory cytokines associated with SLE. Mechanistically, in vitro data support these findings, as co-culture of hESC-MSCs with lipopolysaccharide (LPS)-stimulated BWF1 lymphocytes decreased lymphocyte secretion of TNFα and IL-6, and enhanced the percentage of putative regulatory T cells. This study represents an important step in the development of a commercially scalable and efficacious cell therapy for SLE/LN.