Cytokine targets in lupus nephritis: Current and future prospects

Canonical effects of cytokines on glomerulonephritis: A new outlook in nephrology

Glomerulonephritis (GN) is an important cause of renal inflammation resulting from kidney-targeted adaptive and innate immune responses and consequent glomerular damage. Given the lack of autoantibodies, immune complexes, or the infiltrating immune cells in some forms of GN, for example, focal segmental glomerulosclerosis and minimal change disease, along with paraneoplastic syndrome and a special form of renal involvement in some viral infections, the likeliest causative scenario would be secreted factors, mainly cytokine(s). Since cytokines can modulate the inflammatory mechanisms, severity, and clinical outcomes of GN, it is rational to consider the umbrella term of cytokine GN as a new outlook to reclassify a group of previously known GN. We focus here, particularly, on cytokines that have the central "canonical effect" in the development of GN.

Therapeutically targeting proinflammatory type I interferons in systemic lupus erythematosus: efficacy and insufficiency with a specific focus on lupus nephritis

Type I interferons (IFN-Is) are important players in the immunopathogenesis of systemic lupus erythematosus (SLE). Pathogenic events in patients with SLE are potent triggers of IFN-I induction, yet IFN-I may induce or initiate the immunopathogenesis leading to these events. Because blocking IFN-I is effective in some clinical manifestations of SLE patients, concerns about the efficacy of anti-IFN-I therapy in patients with lupus nephritis remain. Tissues from kidney biopsies of patients with lupus nephritis revealed infiltration of various immune cells and activation of inflammatory signals; however, their correlation with renal damage is not clear, which raises serious concerns about how critical the role of IFN-I is among the potential contributors to the pathogenesis of lupus nephritis. This review addresses several issues related to the roles of IFN-I in SLE, especially in lupus nephritis, including (1) the contribution of IFN-I to the development and immunopathogenesis of SLE; (2) evidence supporting the association of IFN-I with lupus nephritis; (3) therapies targeting IFN-I and IFN-I downstream signaling molecules in SLE and lupus nephritis; (4) findings challenging the therapeutic benefits of anti-IFN-I in lupus nephritis; and (5) a perspective associated with anti-IFN-I biologics for lupus nephritis treatment. In addition to providing clear pictures of the roles of IFN-I in SLE, especially in lupus nephritis, this review addresses the lately published observations and clinical trials on this topic.

Efficacy and safety of telitacicept in patients with lupus nephritis: a single-center, real-world retrospective study

BACKGROUND

Telitacicept, an innovative drug used for the treatment of systemic lupus erythematosus (SLE), can effectively control disease progression and achieve favorable outcomes. While case reports have mentioned the use of Telitacicept in lupus nephritis (LN) treatment, its safety and efficacy in treating patients with LN have not been explored. Therefore, in this study, we aimed to evaluate the safety and efficacy of Telitacicept in managing patients with LN.

METHODS

In a single-center, real-world retrospective study, 30 LN patients with poor response or adverse reactions to conventional glucocorticoids at our Hospital were enrolled to receive Telitacicept. Patients were administered 160 mg of Telitacicept subcutaneously once a week for at least 24 weeks in addition to standard treatment. We assessed the SLE responder index-4 (SRI-4) at the beginning and the end of the treatment period, measured laboratory test indicators at 3, 6, and 9 months, and observed the occurrence of adverse events in these patients.

RESULTS

The SRI-4 response rate was 86.67% (n = 26), with a significantly lower systemic lupus erythematosus disease activity index (SLEDAI) score compared to the baseline. Post Telitacicept treatment, glucocorticoid intake of patients with LN significantly reduced from 50 (IQR:40, 51.25) at baseline to 10 (IQR:5,10) at the endpoint (Z = - 6.547, p < 0.001). Patients with LN showed significantly improved urine occult blood levels after Telitacicept therapy. While the complement (C3 and C4) contents increased, immunoglobulins (IgG, IgA and IgM) reduced markedly (p < 0.001). The negative rate of dsDNA reached 26.67% and adverse events were alleviated post treatment. Only two cases of LN-related adverse reactions were reported, including herpes and infectious fever, respectively. Telitacicept primarily serves as an agent for the induction of remission therapy, with an attainment of complete remission rate standing at a commendable 73.3%.

CONCLUSIONS

Telitacicept treatment reduced disease severity in patients with LN. The initial clinical trial provided supportive evidence for the effectiveness and safety of Telitacicept as a viable treatment option for LN, allowing a reduction in the daily glucocorticoid intake while maintaining a good safety profile, and improving hypocomplementation in LN management.

Precision medicine in lupus nephritis

Lupus nephritis (LN) is a prominent manifestation of systemic lupus erythematosus (SLE), characterized by diverse clinical and histopathological features, imposing a substantial burden on patients. Although the exact cause of SLE remain undetermined, several genetic, epigenetics, hormonal, and other factors are implicated in LN pathogenesis. The management of LN rely on invasive renal biopsies, while the standard therapy of the proliferative form of LN remains empirical and relies on indiscriminate immunosuppressants (IS). These treatments exhibit unsatisfactory remission rates, trigger recurrent renal flares, and entail grave adverse effects (ADEs). The advent of precision medicine into LN entails a concentrated effort to pinpoint essential biomarkers, reshaping the landscape of LN management. The primary objective of this review is to synthesize and summarize existing research findings by elucidating the most prevalent immunological, genetic, and epigenetic alterations and deliberate on management strategies that can pave the way for precision medicine in tackling LN. Novel clinical biomarker such as serum anti-complement component 1q (anti-C1q), with urinary markers including neutrophil gelatinase-associated lipocalin (NGAL), monocyte chemoattractant protein-1 (MCP1) and tumour necrosis-like weak inducers of apoptosis (TWEAK) are strongly correlated with LN. These biomarkers have good sensitivity and specificity and perform better than conventional biomarkers in assessing LN activity. Similarly, more renal-specific genetic and epigenetic alteration have been correlated with LN susceptibility and severity. This includes variants of hyaluronan synthase 2 (HAS2), and platelet-derived growth factor receptor alpha (PDGFRA). In the future, integrating clinical, genetic, epigenetic, and targeted therapies holds promise for guiding precision medicine and improving LN outcomes.

Inhibition of STAT3 alleviates LPS-induced apoptosis and inflammation in renal tubular epithelial cells by transcriptionally down-regulating TASL

BACKGROUND

Systemic lupus erythematosus (SLE) is a common autoimmune disease that impacts various organs. Lupus nephritis (LN) significantly contributes to death in children with SLE. Toll-like receptor (TLR) adaptor interacting with SLC15A4 on the lysosome (TASL) acts as an innate immune adaptor for TLR and is implicated in the pathogenesis of SLE. A transcription factor known as signal transducer and activator of transcription 3 (STAT3), which is known to be linked to autoimmune diseases, is also involved in the development of SLE.

METHODS

Bioinformatics and real-time quantitative PCR (qRT-PCR) was used to detect the expression of STAT3 and TASL in peripheral blood of SLE patients and their correlation. Bioinformatics analysis, qRT-PCR, luciferase assay and chromatin immunoprecipitation (ChIP) were used to verify the regulation of transcription factor STAT3 on TASL. The expression levels of STAT3, TASL and apoptosis-related genes in LPS-induced HK2 cells were detected by qRT-PCR and Western blot. TUNEL staining were used to detect the apoptosis of HK2 cells after LPS stimulation. ELISA and qRT-PCR were used to detect the levels of inflammatory cytokines in the cell culture supernatant. TASL knockdown in HK2 cells was used to detect the changes in apoptosis-related genes and inflammatory factors. The expression level of TASL in LPS-stimulated HK2 cells and its effect on cell apoptosis and inflammatory factors were observed by knocking down and overexpressing STAT3, respectively. It was also verified in a rescue experiment.

RESULTS

The expressions of STAT3 and TASL were higher in SLE than in healthy children, and the expression of STAT3 was positively correlated with TASL. Transcription factor STAT3 can directly and positively regulate the expression of TASL through the promoter region binding site. The expression of STAT3, TASL and inflammatory cytokines was elevated, and the change of apoptosis was up-regulated in LPS-stimulated HK2 cells. Inhibition of STAT3 alleviates LPS-stimulated apoptosis and inflammatory response in HK2 cells through transcriptional regulation of TASL.

CONCLUSIONS

These findings provide new insights into the transcriptional regulation of TASL and provide new evidence of a direct regulatory relationship between signaling nodes in the lupus signaling network.

Pathogenic Gene Spectrum and Clinical Implication in Chinese Patients with Lupus Nephritis

BACKGROUND

Lupus nephritis is a rare immunological disorder. Genetic factors are considered important in its causation. We aim to systematically investigate the rare pathogenic gene variants in patients with lupus nephritis.

METHODS

Whole-exome sequencing was used to screen pathogenic gene variants in 1886 probands with lupus nephritis. Variants were interpreted on the basis of known pathogenic variants or the American College of Medical Genetics and Genomics guidelines and studied by functional analysis, including RNA sequencing, quantitative PCR, cytometric bead array, and Western blotting.

RESULTS

Mendelian form of lupus nephritis was confirmed in 71 probands, involving 63 variants in 39 pathogenic genes. The detection yield was 4%. The pathogenic genes enriched in nuclear factor kappa-B (NF-κB), type I interferon, phosphatidylinositol-3-kinase/serine/threonine kinase Akt (PI3K/AKT), Ras GTPase/mitogen-activated protein kinase (RAS/MAPK), and Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathways. Clinical manifestation patterns were diverse among different signaling pathways. More than 50% of the pathogenic gene variants were reported to be associated with lupus or lupus nephritis for the first time. The identified pathogenic gene variants of lupus nephritis overlapped with those of autoinflammatory and immunodeficiency diseases. Inflammatory signatures, such as cytokine levels of IL-6, IL-8, IL-1 β , IFN α , IFN γ , and IP10 in serum and transcriptional levels of interferon-stimulated genes in blood, were significantly higher in patients with pathogenic gene variants compared with controls. The overall survival rate of patients with pathogenic gene variants was lower than those without pathogenic gene variants.

CONCLUSIONS

A small fraction of patients with lupus nephritis had identifiable pathogenic gene variants, primarily in NF-κB, type I interferon, PI3K/AKT, JAK/STAT, RAS/MAPK, and complement pathways.

Identification of potent target and its mechanism of action of Tripterygium wilfordii Hook F in the treatment of lupus nephritis

AIM

The Chinese anti-rheumatic herbal remedy Tripterygium wilfordii Hook F (TWHF) has been widely shown to be effective in treating lupus nephritis (LN), but the therapeutic targets and mechanisms of action are still unclear. In this study, we aimed to combine mRNA expression profile analysis and network pharmacology analysis to screen the pathogenic genes and pathways involved in LN and to explore the potential targets of TWHF in the treatment of LN.

METHODS

The mRNA expression profiles of LN patients were used to screen differentially expressed genes (DEGs) and to predict associated pathogenic pathways and networks via the Ingenuity Pathway Analysis database. Through molecular docking, we predicted the mechanism by which TWHF interacts with candidate targets.

RESULTS

A total of 351 DEGs were screened from the glomeruli of LN patients and were mainly concentrated in the role of pattern recognition receptors in the recognition of bacteria and viruses and interferon signaling pathways. A total of 130 DEGs were screened from the tubulointerstitium of LN patients, which were concentrated in the interferon signaling pathway. TWHF might be effective in treating LN by hydrogen bonding to regulate the functions of 24 DEGs (including HMOX1, ALB, and CASP1), which are mainly concentrated in the B-cell signaling pathway.

CONCLUSION

The mRNA expression profile of renal tissue from LN patients revealed a large number of DEGs. TWHF has been shown to interact with the DEGs (including HMOX1, ALB and CASP1) through hydrogen bonding to treat LN.

Lupus Nephritis: Improving Treatment Options

Despite improvements in patient and renal death rates following the introduction of potent immunosuppressive drugs in earlier decades, a sizeable fraction of patients with lupus nephritis is burdened with suboptimal or delayed responses, relapses, chronic use of glucocorticoids and accrual of renal (chronic renal insufficiency) and extra-renal organ damage. The recently approved combinatory treatments comprising belimumab or voclosporin added to conventional agents, especially mycophenolate, hold promise for further improving disease outcomes and enabling a faster steroid tapering, thus being relevant to the treat-to-target context. However, it remains uncertain whether these dual regimens should become the first-line choice for all patients or instead be prioritized to certain subgroups. In the present article, we summarize the existing lupus nephritis management recommendations, followed by a critical appraisal of the randomized trials of belimumab and voclosporin, as well as the available data on obinutuzumab and other novel compounds under development. We conclude that pending the identification of accurate clinical, histological, or translational predictors for guiding personalized decisions, it is of utmost importance that lupus nephritis patients are monitored closely with appropriate treatment adjustments aiming at a prompt, deep response to ensure long-term preservation of kidney function.

Autoantigen spermatid nuclear transition protein 1 enhances pro-inflammatory cytokine production stimulated by anti-DNA autoantibodies in macrophages

Introduction

Lupus nephritis (LN), a severe manifestation of systemic lupus erythematosus (SLE), is associated with high fatality rate in patients. The pathogenesis of lupus nephritis is complex and has not been fully elucidated. Kidney inflammation, renal cell damage, and accumulation of immune complexes in the glomerular basement membrane often occur in patients with lupus nephritis. Spermatid nuclear transition protein 1 (TNP1) might be a potentially interesting autoantigen in exploring the pathogenesis and therapy of lupus nephritis.

Objective

This study aimed to explore the effect of TNP1 and its complexes with anti-double-stranded DNA antibodies on the levels of interleukin-6 (IL-6) and interferon-α (IFN-α) in vitro.

Methods

We studied the effect of the synthetic peptide of the autoantigen on the pathogenic characteristics of the G2-6 and G5-8 antibodies in mouse macrophages, using enzyme-linked immunosorbent assay, quantitative RT-PCR, western blotting, and flow cytometry.

Results

The antibodies exhibited cross-reactivity to spermatid TNP1 in direct-binding and competitive enzyme-linked immunosorbent assay. Results of quantitative RT-PCR and western blotting revealed that the antibodies alone enhanced the levels of IL-6 and IFN-α transcripts and proteins, respectively. Flow cytometry revealed that treatment with the autoantigen enhanced the cell-penetrating activities of G2-6 and G5-8 and remarkably increased the cytokine levels.

Conclusion

TNP1 enhanced the cell-penetrating activities of anti-dsDNA auto-Abs, G2-6 and G5-8, and remarkably increased the levels of IL-6 and IFN-α in macrophages, suggesting that TNP1 and cell-penetrating pathogenic anti-dsDNA auto-Abs is potential targets for future therapeutic approaches to treat LN/SLE.

Knockout of the KH-Type Splicing Regulatory Protein Drives Glomerulonephritis in MRL-Faslpr Mice

KH-type splicing regulatory protein (KSRP) is an RNA-binding protein that promotes mRNA decay and thereby negatively regulates cytokine expression at the post-transcriptional level. Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by dysregulated cytokine expression causing multiple organ manifestations; MRL-Faslpr mice are an established mouse model to study lupus disease pathogenesis. To investigate the impact of KSRP on lupus disease progression, we generated KSRP-deficient MRL-Faslpr mice (MRL-Faslpr/KSRP-/- mice). In line with the predicted role of KSRP as a negative regulator of cytokine expression, lupus nephritis was augmented in MRL-Faslpr/KSRP-/- mice. Increased infiltration of immune cells, especially of IFN-γ producing T cells and macrophages, driven by enhanced expression of T cell-attracting chemokines and adhesion molecules, seems to be responsible for worsened kidney morphology. Reduced expression of the anti-inflammatory interleukin-1 receptor antagonist may be another reason for severe inflammation. The increase of FoxP3+ T cells detected in the kidney seems unable to dampen the massive kidney inflammation. Interestingly, lymphadenopathy was reduced in MRL-Faslpr/KSRP-/- mice. Altogether, KSRP appears to have a complex role in immune regulation; however, it is clearly able to ameliorate lupus nephritis.

Hsa_circ_0010957 knockdown attenuates lipopolysaccharide-induced HK2 cell injury by regulating the miR-1224-5p/IRAK1 axis

Circular RNAs (circRNAs) are involved in the progression of various diseases, including lupus nephritis. Hsa_circ_0010957 is reported to be dysregulated in lupus nephritis, but the exact function of this circRNA is unknown. This research aims to study the function and mechanism of circRNA hsa_circ_0010957 in a lipopolysaccharide (LPS)-induced cellular model of lupus nephritis. Human renal proximal tubular cell line HK2 cells were challenged by LPS. Hsa_circ_0010957, microRNA-1224-5p (miR-1224-5p), and interleukin-1 receptor-associated kinase 1 (IRAK1) abundances were examined by quantitative reverse transcription polymerase chain reaction or western blot. LPS-induced damage was evaluated via cell viability, apoptosis, inflammatory response and oxidative injury. The target interaction was analyzed by dual-luciferase reporter analysis and RNA immunoprecipitation. Hsa_circ_0010957 abundance was enhanced in LPS-challenged HK2 cells. Hsa_circ_0010957 knockdown alleviated LPS-induced apoptosis, the inflammatory response and oxidative injury in HK2 cells. MiR-1224-5p was targeted by hsa_circ_0010957, and miR-1224-5p knockdown reversed the influence of hsa_circ_0010957 silence on LPS-induced injury. IRAK1 was targeted via miR-1224-5p, and hsa_circ_0010957 could regulate IRAK1 by miR-1224-5p. MiR-1224-5p overexpression could mitigate LPS-induced apoptosis, the inflammatory response and oxidative injury, and this effect was abolished by IRAK1. Hsa_circ_0010957 silence weakened LPS-induced HK2 cell apoptosis, the inflammatory response and oxidative injury via regulating the miR-1224-5p/IRAK1 axis.

Interferons in Systemic Lupus Erythematosus

Skewing of type I interferon (IFN) production and responses is a hallmark of systemic lupus erythematosus (SLE). Genetic and environmental contributions to IFN production lead to aberrant innate and adaptive immune activation even before clinical development of disease. Basic and translational research in this arena continues to identify contributions of IFNs to disease pathogenesis, and several promising therapeutic options for targeting of type I IFNs and their signaling pathways are in development for treatment of SLE patients.

Neutralization of IL-6 inhibits formation of autoreactive TH17 cells but does not prevent loss of renal function in experimental autoimmune glomerulonephritis

In anti-glomerular basement membrane glomerulonephritis (anti-GBM GN), antibodies and T cells directed against the Goodpasture antigen, the non-collagenous domain of the α3-chain of type IV collagen (α3(IV)NC1), provoke renal inflammation resulting in rapidly progressing crescentic GN. Interleukin 6 (IL-6) is a pleiotropic cytokine with both pro- and anti-inflammatory activities, and IL-6 blockade is successfully used for treatment of diseases associated with acute and chronic inflammation. However, the role of IL-6 in anti-GBM GN is unclear. Here, we use the mouse model of experimental autoimmune glomerulonephritis (EAG) to study the role of IL-6 in anti-GBM GN. DBA/1J mice were immunized with α3(IV)NC1 and developed fatal crescentic GN. Treatment of mice with neutralizing anti-IL-6 antibodies impaired the generation of α3(VI)NC1-specific TH1 and TH17 cells. However, despite lasting reduction of the TH17 cell response, antibody treatment did not prevent crescentic GN. Antibody treatment was also ineffective in a therapeutic setting with pre-existing autoantibodies and T cells. In conclusion, our results indicate that although the blockade of IL-6 impairs the development of autoimmunity against α3(VI)NC1, this treatment does not ameliorate crescentic GN both in a preemptive and a therapeutic approach.

Cytokine clusters as potential diagnostic markers of disease activity and renal involvement in systemic lupus erythematosus

OBJECTIVE

To describe interactions among cytokines and to identify subgroups of systemic lupus erythematosus (SLE) patients based on cytokine levels using principal component analysis and cluster analysis.

METHODS

Levels of 12 cytokines were measured using sensitive multiplex bead assays and associations with SLE features including disease activity and renal involvement were assessed.

RESULTS

In a group of 203 SLE patients, strong correlations were observed between interleukin (IL)6 and interferon (IFN)γ levels (r = 0.624), IL17 and IFNγ levels (r = 0.768), and macrophage inflammatory protein (MIP)1α and MIP1β levels (r = 0.675). Cluster analysis revealed two distinct patient groups characterized by high levels of IL8, MIP1α, and MIP1β (group 1) or of IL2, IL6, IL10, IL12, IFNγ, and tumor necrosis factor α (group 2). Active disease was more common in group 1 (49/88, 55.7%) than in group 2 (40/115, 34.8%). More patients in group 2 had renal involvement (42/115, 36.5%) than in group 1 (22/88, 25%).

CONCLUSIONS

Assessment of cytokine profiles can identify distinct SLE patient subgroups and aid in understanding clinical heterogeneity and immunological phenotypes.

Elevated urinary IL-36γ in patients with active lupus nephritis and response to treatment

INTRODUCTION

IL-36 is a new member of the IL-1 family with pro-inflammatory properties. Serum levels of IL-36 are elevated in patients with Systemic Lupus Erythematosus (SLE). However, no data is available on urinary levels of IL-36 in Lupus Nephritis (LN). In psoriasis expression of IL-36 is site specific and expressed in skin. Hence, we studied urinary levels of IL-36 cytokines in SLE patients.

METHODS

A total of 196 patients with SLE [97 active LN patients (ALN), 42 inactive LN (ILN) and 57 active lupus patients with no renal involvement (ANR)] and 25 healthy subjects were recruited for the study after obtaining informed consent. Urinary and plasma IL-36α, IL-36γ and IL-36Ra levels were measured by ELISA.

RESULTS

Out of 196 patients 178 were females. Urinary IL-36γ levels in SLE patients [0(14.3) pg/ml] were significantly higher than healthy controls [0(0) pg/ml, (P < 0.01)]. Patients with ALN [0(40.6) pg/ml] had significantly higher IL-36γ when compared to ANR [0(0) pg/ml] as well as ILN [0(0) pg/ml]. Urinary IL-36γ levels in ALN patients had a fair correlation with renal SLEDAI (r = 0.26, P = 0.004).The levels reduced significantly post 3 months in patients with ALN. No inverse relationship was noted between IL-36Ra and IL-36α/IL36γ levels.

CONCLUSION

Urinary IL-36γ is produced locally in kidney, correlates with renal disease activity and reduces upon treatment, suggesting that it may have a role in pathogenesis of LN.

Management of Severe Refractory Systemic Lupus Erythematosus: Real-World Experience and Literature Review

Systemic lupus erythematosus (SLE) is a highly heterogeneous disease affecting multiple organs and is characterized by an aberrant immune response. Although the mortality of SLE has decreased significantly since the application of glucocorticoids, severe or refractory SLE can potentially cause irreversible organ damage and contribute to the disease morbidity and mortality. Early recognition of severe SLE or life-threatening conditions is of great challenge to clinicians since the onset symptoms can be rapid and aggressive, involving the visceral organs of the neuropsychiatric, gastrointestinal, hematologic, renal, pulmonary, and cardiovascular systems, etc. Additionally, SLE patients with specific comorbidities and detrimental complications could lead to a clinical dilemma and contribute to poor prognosis. Prompt and adequate treatment for severe refractory SLE is crucial for a better prognosis. However, as evidence from well-designed randomized controlled trials is limited, this review aims to provide real-world evidence based on cohort studies from Peking Union Medical College Hospital, the national tertiary referral center in China, together with the literature, on clinical characteristics, risks and prognostic factors, and treatment strategies for severe and/or refractory SLE.

The Network of Inflammatory Mechanisms in Lupus Nephritis

Several signaling pathways are involved in the progression of kidney disease in humans and in animal models, and kidney disease is usually due to the sustained activation of these pathways. Some of the best understood pathways are specific proinflammatory cytokine and protein kinase pathways (e.g., protein kinase C and mitogen-activated kinase pathways, which cause cell proliferation and fibrosis and are associated with angiotensin II) and transforming growth factor-beta (TGF-β) signaling pathways (e.g., the TGF-β signaling pathway, which leads to increased fibrosis and kidney scarring. It is thus necessary to continue to advance our knowledge of the pathogenesis and molecular biology of kidney disease and to develop new treatments. This review provides an update of important findings about kidney diseases (including diabetic nephropathy, lupus nephritis, and vasculitis, i.e., vasculitis with antineutrophilic cytoplasmic antibodies). New disease targets, potential pathological pathways, and promising therapeutic approaches from basic science to clinical practice are presented, and the blocking of JAK/STAT and TIM-1/TIM-4 signaling pathways as potential novel therapeutic agents in lupus nephritis is discussed.

TNIP1/ABIN1 and lupus nephritis: review

SLE is a complex autoimmune disease with genetic, epigenetic, immune-regulatory, environmental and hormonal factors. Kidney inflammation and injury, termed lupus nephritis (LN), occurs in over half of patients with SLE and is a leading cause of disability and death. There is a high degree of short-term and long-term side effects associated with current LN therapies and they are not effective for many patients. Thus, novel therapies with reduced toxicity and improved efficacy are drastically needed. Many of the known LN susceptibility genes have functions that mediate inflammation via cytokine/chemokine production and activation of myeloid and B cells. Understanding the cellular and molecular mechanisms mediated by these variant gene products provides valuable insight for the development of improved and personalised diagnostics and therapeutics. This review describes variants in the TNIP1 (tumour necrosis factor α-induced protein 3-interacting protein 1) gene associated with risks for SLE and LN and potential roles for loss of function of its protein product ABIN1 in the activation of myeloid and B-cell-mediated injury in LN.

Systemic autoinflammatory diseases

Systemic autoinflammatory diseases (SAIDs) are a growing group of disorders caused by a dysregulation of the innate immune system leading to episodes of systemic inflammation. In 1997, MEFV was the first gene identified as disease causing for Familial Mediterranean Fever, the most common hereditary SAID. In most cases, autoinflammatory diseases have a strong genetic background with mutations in single genes. Since 1997 more than 30 new genes associated with autoinflammatory diseases have been identified, affecting different parts of the innate immune system. Nevertheless, for at least 40-60% of patients with phenotypes typical for SAIDs, a distinct diagnosis cannot be met, leading to undefined SAIDs (uSAIDs). However, SAIDs can also be of polygenic or multifactorial origin, with environmental influence modulating the phenotype. The implementation of a disease continuum model combining the adaptive and the innate immune system with autoinflammatory and autoimmune diseases shows the complexity of SAIDs and the importance of new methods to elucidate molecular changes and causative factors in SAIDs. Diagnosis is often based on clinical presentation and genetic testing. The timeline from onset to diagnosis takes up to 7.3 years, highlighting the indisputable need to identify new treatment and diagnostic targets. Recently, other factors are under investigation as additional contributors to the pathogenesis of SAIDs. This review gives an overview of pathogenesis and etiology of SAIDs, and summarizes recent diagnosis and treatment options.

Update on the cellular and molecular aspects of lupus nephritis

Recent progress has highlighted the involvement of a variety of innate and adaptive immune cells in lupus nephritis. These include activated neutrophils producing extracellular chromatin traps that induce type I interferon production and endothelial injury, metabolically-rewired IL-17-producing T-cells causing tissue inflammation, follicular and extra-follicular helper T-cells promoting the maturation of autoantibody-producing B-cells that may also sustain the formation of germinal centers, and alternatively activated monocytes/macrophages participating in tissue repair and remodeling. The role of resident cells such as podocytes and tubular epithelial cells is increasingly recognized in regulating the local immune responses and determining the kidney function and integrity. These findings are corroborated by advanced, high-throughput genomic studies, which have revealed an unprecedented amount of data highlighting the molecular heterogeneity of immune and non-immune cells implicated in lupus kidney disease. Importantly, this research has led to the discovery of putative pathogenic pathways, enabling the rationale design of novel treatments.