JAK3-STAT pathway blocking benefits in experimental lupus nephritis

LncRNA XIST/miR-381-3P/STAT1 axis as a potential biomarker for lupus nephritis

OBJECTIVE

We aim to investigate the potential roles of key genes in the development of lupus nephritis (LN), screen key biomarkers, and construct the lncRNA XIST/miR-381-3P/STAT1 axis by using bioinformatic prediction combined with clinical validation, thereby providing new targets and insights for clinical research.

METHODS

Gene expression microarrays GSE157293 and GSE112943 were downloaded from the GEO database to obtain differentially expressed genes (DEGs), followed by enrichment analyses on these DEGs, which were enriched and analyzed to construct a protein-protein interaction (PPI) network to screen core genes. The lncRNA-miRNA-mRNA regulatory network was predicted and constructed based on the miRNA database. 37 female patients with systemic lupus erythematosus (SLE) were recruited to validate the bioinformatics results by exploring the diagnostic value of the target ceRNA axis in LN by dual luciferase and real-time fluorescence quantitative PCR (RT-qPCR) and receiver operating characteristic (ROC).

RESULTS

The data represented that a total of 133 differential genes were screened in the GSE157293 dataset and 2869 differential genes in the GSE112943 dataset, yielding a total of 26 differentially co-expressed genes. Six core genes (STAT1, OAS2, OAS3, IFI44, DDX60, and IFI44L) were screened. Biological functional analysis identified key relevant pathways in LN. ROC curve analysis suggested that lncRNA XIST, miR-381-3P, and STAT1 could be used as potential molecular markers to assist in the diagnosis of LN.

CONCLUSION

STAT1 is a key gene in the development of LN. In conclusion, lncRNA XIST, miR-381-3P, and STAT1 can be used as new molecular markers to assist in the diagnosis of LN, and the lncRNA XIST/miR-381-3P/STAT1 axis may be a potential therapeutic target for LN.

Drug repurposing for glomerular diseases: an underutilized resource

Drug repurposing in glomerular disease can deliver opportunities for steroid-free regimens, enable personalized multi-target options for resistant or relapsing disease and enhance treatment options for understudied populations (for example, children) and in resource-limited settings. Identification of drug-repurposing candidates can be data driven, which utilizes existing data on disease pathobiology, drug features and clinical outcomes, or experimental, which involves high-throughput drug screens. Information from databases of approved drugs, clinical trials and PubMed registries suggests that at least 96 drugs on the market cover 49 targets with immunosuppressive potential that could be candidates for drug repurposing in glomerular disease. Furthermore, evidence to support drug repurposing is available for 191 immune drug target-glomerular disease pairs. Non-immunological drug repurposing includes strategies to reduce haemodynamic overload, podocyte injury and kidney fibrosis. Recommended strategies to expand drug-repurposing capacity in glomerular disease include enriching drug databases with glomeruli-specific information, enhancing the accessibility of primary clinical trial data, biomarker discovery to improve participant selection into clinical trials and improve surrogate outcomes and initiatives to reduce patent, regulatory and organizational hurdles.

[Jianpi Zishen granule inhibits podocyte autophagy in systemic lupus erythematosus: a network pharmacology and clinical study]

OBJECTIVE

To explore the therapeutic mechanism of Jianpi Zishen (JPZS) granules for systemic lupus erythematosus(SLE) in light of podocyte autophagy regulation.

METHODS

TCMSP, GeneCards, OMIM, and TTD databases were used to obtain the targets of JPZS granules, SLE, and podocyte autophagy. The protein-protein interaction network was constructed using Cytoscape, and the key active ingredients and targets were screened for molecular docking. In the clinical study, 46 patients with SLE were randomized into two groups to receive baseline treatment with prednisone acetate and mycophenolate mofetil (control group) and additional treatment with JPZS granules (observation group) for 12 weeks, with 10 healthy volunteers as the healthy control group. Urinary levels of nephrin and synaptopodin of the patients were detected with ELISA. Western blotting was performed to determine peripheral blood levels of p-JAK1/JAK1, p-STAT1/STAT1, LC3II/LC3I, and p62 proteins of the participants.

RESULTS

Four key active ingredients and 5 core target genes (STAT1, PIK3CG, MAPK1, PRKCA, and CJA1) were obtained, and enrichment analysis identified the potentially involved signaling pathways including AGE-RAGE, JAK/STAT, EGFR, and PI3K/Akt. Molecular docking analysis showed that STAT1 was the most promising target protein with the highest binding activity, suggesting its role as an important mediator for signal transduction after JPZS granule treatment. In the 43 SLE patients available for analysis, treatment with JPZS granule significantly reduced serum levels of p-JAK1/JAK1, p-STAT1/STAT1, and LC3II/LC3I (P < 0.05 or 0.01), increased the protein level of P62 (P < 0.05), and reduced urinary levels of nephrin and synaptopodin (P < 0.05).

CONCLUSION

The therapeutic effect of JPZS granules on SLE is mediated probably by coordinated actions of quercetin, kaempferol, β-sitosterol, and isorhamnetin on their target gene STAT1 to inhibit the JAK/STAT pathway, thus suppressing autophagy and alleviating podocyte injuries in SLE.

JAK Inhibition as a Potential Treatment Target in Systemic Lupus Erythematosus

Janus kinase (JAK)/signal transducers and activators of transcription (STATs) are a group of molecules responsible for signal transduction of multiple cytokines and growth factors in different cell types, involved in the maintenance of immune tolerance. Thus, the dysregulation of this pathway plays a crucial role in the pathogenesis of multiple autoimmune, inflammatory, and allergic diseases and is an attractive treatment target. JAK inhibitors (JAKinibs) have been approved in the treatment of multiple autoimmune diseases including rheumatoid arthritis (RA), psoriatic arthritis (PsA) and ankylosing spondylitis (SPA). In SLE, there is a plethora of ongoing trials evaluating their efficacy, with tofacitinib, baricitinib and deucravacitinib showing promising results, without major safety concerns. In this review, we will discuss the rationale of targeting JAKinibs in SLE and summarize the clinical data of efficacy and safety of JAKinibs in SLE patients.

Whole blood hydroxychloroquine: Does genetic polymorphism of cytochrome P450 enzymes have a role?

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease with a wide range of clinical manifestations and multifactorial etiologies ranging from environmental to genetic. SLE is associated with dysregulated immunological reactions, with increased immune complex formation leading to end-organ damages such as lupus nephritis, cutaneous lupus, and musculoskeletal disorders. Lupus treatment aims to reduce disease activity, prevent organ damage, and improve long-term patient survival and quality of life. Antimalarial, hydroxychloroquine (HCQ) is used as a first-line systemic treatment for lupus. It has shown profound efficacy in lupus and its associated conditions. However, wide variation in terms of clinical response to this drug has been observed among this group of patients. This variability has limited the potential of HCQ to achieve absolute clinical benefits. Several factors, including genetic polymorphisms of cytochrome P450 enzymes, have been stipulated as key entities leading to this inter-individual variation. Thus, there is a need for more studies to understand the role of genetic polymorphisms in CYP450 enzymes in the clinical response to HCQ. Focusing on the role of genetic polymorphism on whole blood HCQ in lupus disorder, this review aims to highlight up-to-date pathophysiology of SLE, the mechanism of action of HCQ, and finally the role of genetic polymorphism of CYP450 enzymes on whole blood HCQ level as well as clinical response in lupus.

Utilizing a human TLR selective ligand in a humanized immune system mouse model to investigate human TLR4 signaling

Mouse models with humanized immune systems are becoming increasingly prevalent in pharmaceutical research as a platform for preclinical testing with potential for greater translatability to clinical applications. However, the presence of both mouse and human cells that respond to TLR ligands poses a challenge for investigating therapeutic modalities targeting TLR signaling. AZ617 is a human TLR4 agonist, which has been shown in vitro to preferentially induce human cytokines via the TLR4 signaling pathway. We sought to examine the ability of AZ617 to preferentially induce human cytokines in CD34+ stem cell-engrafted NOG-EXL mice (huNOG-EXL), to determine its suitability as an in vivo human functional readout. AZ617 elicited a strong human TNFα and IL-6 response in vivo that demonstrated a 10- and 5-fold preference, respectively, over the mouse TNFα and IL-6. To assess efficacy of inhibiting a key protein in the TLR4 signaling pathway, PF-06650833, a small molecule inhibitor of IRAK4, was used as a tool molecule. PF-0660833 was found to effectively inhibit AZ617-induced human TNFα release in vitro. Likewise, PF-06650833 reduced AZ617-induced human TNFα in the huNOG-EXL mouse model, with a weaker effect on human IL-6. A longitudinal study tracking functionality of monocytes revealed that the ability of monocytes to respond to ex vivo stimuli was increased by 21 weeks after engraftment. Taken together, our data suggests that human selective TLR ligands could preferentially drive cytokine production from human cells in huNOG-EXL mice. This model will allow for investigation of pharmacological inhibition of human TLR signaling pathways in an in vivo model system.

Janus kinase inhibitors in systemic lupus erythematosus: implications for tyrosine kinase 2 inhibition

Aberrant activation of the Janus kinase (JAK) and signal transducer and activator of transcription (STAT) pathway is common in systemic lupus erythematosus (SLE), conferring immune-mediated properties in target tissues. Multiple cytokines activate different combinations of JAKs and STATs to alter the cell fate of target tissue and induce end-organ damage. Thus, the simultaneous blockade of several different cytokines by small molecules acting downstream intracellular signalling has gained traction. JAK inhibitors have been approved for the treatment of several rheumatic diseases, yet hitherto not for SLE. Nevertheless, JAK inhibitors including tofacitinib, baricitinib, and deucravacitinib have shown merit as treatments for SLE. Tofacitinib, a JAK1/3 inhibitor, reduced cholesterol levels, improved vascular function, and decreased the type I interferon signature in SLE patients. Baricitinib, a JAK1/2 inhibitor, demonstrated significant improvements in lupus rashes and arthritis in a phase 2 and a phase 3 randomised controlled trial, but the results were not replicated in another phase 3 trial. Deucravacitinib, a selective tyrosine kinase 2 (TYK2) inhibitor, yielded greater response rates than placebo in a phase 2 trial of SLE and will be investigated in larger phase 3 trials. TYK2 is activated in response to cytokines actively involved in lupus pathogenesis; this review highlights the potential of targeting TYK2 as a promising therapy for SLE.

The Interplay between Immune and Metabolic Pathways in Kidney Disease

Kidney disease is a significant health problem worldwide, affecting an estimated 10% of the global population. Kidney disease encompasses a diverse group of disorders that vary in their underlying pathophysiology, clinical presentation, and outcomes. These disorders include acute kidney injury (AKI), chronic kidney disease (CKD), glomerulonephritis, nephrotic syndrome, polycystic kidney disease, diabetic kidney disease, and many others. Despite their distinct etiologies, these disorders share a common feature of immune system dysregulation and metabolic disturbances. The immune system and metabolic pathways are intimately connected and interact to modulate the pathogenesis of kidney diseases. The dysregulation of immune responses in kidney diseases includes a complex interplay between various immune cell types, including resident and infiltrating immune cells, cytokines, chemokines, and complement factors. These immune factors can trigger and perpetuate kidney inflammation, causing renal tissue injury and progressive fibrosis. In addition, metabolic pathways play critical roles in the pathogenesis of kidney diseases, including glucose and lipid metabolism, oxidative stress, mitochondrial dysfunction, and altered nutrient sensing. Dysregulation of these metabolic pathways contributes to the progression of kidney disease by inducing renal tubular injury, apoptosis, and fibrosis. Recent studies have provided insights into the intricate interplay between immune and metabolic pathways in kidney diseases, revealing novel therapeutic targets for the prevention and treatment of kidney diseases. Potential therapeutic strategies include modulating immune responses through targeting key immune factors or inhibiting pro-inflammatory signaling pathways, improving mitochondrial function, and targeting nutrient-sensing pathways, such as mTOR, AMPK, and SIRT1. This review highlights the importance of the interplay between immune and metabolic pathways in kidney diseases and the potential therapeutic implications of targeting these pathways.

Targeted Therapy for SLE-What Works, What Doesn't, What's Next

For many years, the failure of randomized controlled trials (RCTs) has prevented patients with systemic lupus erythematosus (SLE) from benefiting from biological drugs that have proved to be effective in other rheumatological diseases. Only two biologics are approved for SLE, however they can only be administered to a restricted proportion of patients. Recently, several phase II RCTs have evaluated the efficacy and safety of new biologics in extra-renal SLE and lupus nephritis. Six drug trials have reported encouraging results, with an improvement in multiple clinical and serological outcome measures. The possibility of combining B-cell depletion and anti-BLyS treatment has also been successfully explored.

Lupus Nephritis: New and Emerging Biologic and Targeted Therapies

Lupus nephritis (LN) is a severe complication of systemic lupus erythematosus (SLE), a polyclonal systemic autoimmunity directed against nuclear and other self-antigens. SLE/LN affects mostly females during childbearing age, which puts them at risk for the progression of chronic kidney disease (CKD), cardiovascular disease, and pregnancy complications. The current management of LN involves the use of drugs with significant toxicities, and despite many attempts at novel drug interventions, the overall treatment efficacy has remained low. In this article, we discuss recent drug approvals and the upcoming pipeline of novel medications tested in clinical trials to improve effectiveness in terms of LN disease activity, LN relapse, and progression of LN-related CKD. In this context, we discuss (1) drugs with the potential to achieve these treatment goals by modulating SLE activity as the driving force for LN (e.g., belimumab, obinutuzumab, anifrolumab, and others); (2) drugs with SLE-non specific renoprotective effects by targeting non-immune mechanisms of LN progression (dapagliflozin, empagliflozin); and (3) drugs with dual immunosuppressive and antiproteinuric effects (voclosporin). Increasing the number of possible drug options will help to improve the management of LN in terms of efficacy and safety, and enable a more personalized treatment approach.

Targeted Small Molecules for Systemic Lupus Erythematosus: Drugs in the Pipeline

Despite the uncertainty of the pathogenesis of systemic lupus erythematosus, novel small molecules targeting specific intracellular mechanisms of immune cells are being developed to reverse the pathophysiological processes. These targeted molecules have the advantages of convenient administration, lower production costs, and the lack of immunogenicity. The Janus kinases, Bruton's tyrosine kinases, and spleen tyrosine kinases are important enzymes for activating downstream signals from various receptors on immune cells that include cytokines, growth factor, hormones, Fc, CD40, and B-cell receptors. Suppression of these kinases impairs cellular activation, differentiation, and survival, leading to diminished cytokine actions and autoantibody secretion. Intracellular protein degradation by immunoproteasomes, levered by the cereblon E3 ubiquitin ligase complex, is an essential process for the regulation of cellular functions and survival. Modulation of the immunoproteasomes and cereblon leads to depletion of long-lived plasma cells, reduced plasmablast differentiation, and production of autoantibodies and interferon-α. The sphingosine 1-phosphate/sphingosine 1-phosphate receptor-1 pathway is responsible for lymphocyte trafficking, regulatory T-cell/Th17 cell homeostasis, and vascular permeability. Sphingosine 1-phosphate receptor-1 modulators limit the trafficking of autoreactive lymphocytes across the blood-brain barrier, increase regulatory T-cell function, and decrease production of autoantibodies and type I interferons. This article summarizes the development of these targeted small molecules in the treatment of systemic lupus erythematosus, and the future prospect for precision medicine.

Potential Use of Janus Kinase Inhibitors in the Treatment of Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a chronic, autoimmune disease with unclear pathogenesis. One characteristic of SLE is pro-inflammatory and anti-inflammatory cytokine imbalance. Janus kinase (JAK) is an intracellular non-receptor tyrosine kinase essential for many cytokine signaling pathways. Dysregulation of the JAK/signal transduction and transcriptional activator (STAT) pathway is an important process in SLE pathogenesis. Targeting JAK/STAT proteins can simultaneously block the functions of multiple cytokines. Current SLE treatment with non-specific corticosteroids and immunosuppressants can cause many adverse reactions. Therefore, treatments designed to control specific molecular targets for SLE are desirable. JAK inhibitors (JAKis) are a potential treatment for rheumatic diseases; however, the use of targeted signaling pathways to treat SLE remains a challenge, and its efficacy has not been determined. JAKis have shown positive results in reducing the use of glucocorticoids and/or non-specific immunosuppressants for SLE. JAKis are currently undergoing several clinical trials and expected to be the next stage in the treatment of SLE. Therefore, inhibition of the JAK/STAT pathway through JAKis may improve traditional treatment strategies for SLE.

HERC6 is upregulated in peripheral blood mononuclear cells of patients with systemic lupus erythematosus and promotes the disease progression

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease. Peripheral blood mononuclear cells (PBMCs) are any peripheral blood cell with round nuclei, including lymphocytes (T cells, B cells) and monocytes, whose physicochemical properties are randomized by obvious immune changes, and are a potentially effective source of SLE blood test samples and therapeutic targets. This study aimed to explore the upregulation molecules of PBMCs in patients with SLE and to explore their biological role. Homologous to the E6-AP carboxyl terminus (HECT) and regulator of chromosome condensation 1 (RCC1)-like domain (RLD) containing E3 ubiquitin protein ligase family member 6 (HERC6) expression was found significantly upregulated in four Gene Expression Omnibus gene sets. Moreover, HERC6 expression was upregulated in PBMCs from SLE patients compared with that in PBMCs from normal donors. HERC6 was significantly associated with SLE clinical phenotypes such as complement C3 content, erythrocyte sedimentation rate, and SLE disease activity index. In vitro, knockdown of HERC6 inhibited PBMC apoptosis, inflammatory response, and janus kinase (JAK)/signal transducer and activator of transcription (STAT) signalling pathway, while overexpression of HERC6 led to the opposite results. In addition, AG490, a JAK/STAT pathway inhibitor, reversed the promoting effect of HERC6 overexpression on PBMC apoptosis and inflammation. In conclusion, the level of HERC6 in PBMCs in patients with SLE was upregulated. Overexpression of HERC6 promoted PBMC apoptosis and inflammatory response, which was involved in the JAK/STAT pathway.

Pathological relevance and treatment perspective of JAK targeting in systemic lupus erythematosus

INTRODUCTION

The pathogenesis of systemic lupus erythematosus (SLE) involves abnormalities in both acquired and innate immune system, which is mediated by numerous cytokines. Janus kinase (JAK) plays important roles in the signaling pathways of those cytokines and is an attractive therapeutic target for SLE. Currently, multiple clinical trials using JAK inhibitors with different selectivities for JAK family proteins are being conducted in SLE.

AREA COVERED

In this article, we provide an overview of the pathological relevance of JAK and the clinical implications of JAK inhibitors in SLE based on recent reports.

EXPERT OPINION

JAK inhibitors have the potential to modulate various immune networks through a variety of mechanisms, potentially regulating the complex immunopathogenesis in SLE. SLE is a clinically and immunologically heterogeneous disease; therefore, precision medicine is required to maximize the efficacy of JAK inhibitors. Further studies are needed to determine their risk-benefit ratio and selection of the most appropriate patients for JAK inhibitors.

The Th17/IL-17 Axis and Kidney Diseases, With Focus on Lupus Nephritis

Systemic lupus erythematosus (SLE) is a disease characterized by dysregulation and hyperreactivity of the immune response at various levels, including hyperactivation of effector cell subtypes, autoantibodies production, immune complex formation, and deposition in tissues. The consequences of hyperreactivity to the self are systemic and local inflammation and tissue damage in multiple organs. Lupus nephritis (LN) is one of the most worrying manifestations of SLE, and most patients have this involvement at some point in the course of the disease. Among the effector cells involved, the Th17, a subtype of T helper cells (CD4+), has shown significant hyperactivation and participates in kidney damage and many other organs. Th17 cells have IL-17A and IL-17F as main cytokines with receptors expressed in most renal cells, being involved in the activation of many proinflammatory and profibrotic pathways. The Th17/IL-17 axis promotes and maintains repetitive tissue damage and maladaptive repair; leading to fibrosis, loss of organ architecture and function. In the podocytes, the Th17/IL-17 axis effects include changes of the cytoskeleton with increased motility, decreased expression of health proteins, increased oxidative stress, and activation of the inflammasome and caspases resulting in podocytes apoptosis. In renal tubular epithelial cells, the Th17/IL-17 axis promotes the activation of profibrotic pathways such as increased TGF-β expression and epithelial-mesenchymal transition (EMT) with consequent increase of extracellular matrix proteins. In addition, the IL-17 promotes a proinflammatory environment by stimulating the synthesis of inflammatory cytokines by intrinsic renal cells and immune cells, and the synthesis of growth factors and chemokines, which together result in granulopoiesis/myelopoiesis, and further recruitment of immune cells to the kidney. The purpose of this work is to present the prognostic and immunopathologic role of the Th17/IL-17 axis in Kidney diseases, with a special focus on LN, including its exploration as a potential immunotherapeutic target in this complication.

JAK Inhibitors: Prospects in Connective Tissue Diseases

The dysregulation of the JAK-STAT pathway is associated with various immune disorders. Four JAK inhibitors have been approved for rheumatoid arthritis (RA), and numerous JAK inhibitors are currently being tested in phase II and III trials for the treatment of various autoimmune inflammatory diseases. In this narrative review, we elucidate the involvement of the JAK-STAT signaling pathway in the pathogenesis of connective tissue diseases (CTDs). We also discuss the efficacy of the first- and second-generation JAK inhibitors (tofacitinib, baricitinib, ruxolitinib, peficitinib, filgotinib, upadacitinib, solcitinib, itacitinib, decernotinib, R333, and pf-06651600) for CTDs including RA, systemic lupus erythematosus, dermatomyositis, systemic sclerosis, Sjögren's syndrome, and vasculitis, based on laboratory and clinical research findings. JAK inhibitors have great potential for the treatment of various CTDs by reducing multiple cytokine production and suppressing inflammation, with the advantages of rapid onset in an oral formulation and decreased corticosteroid dependence and the associated adverse events, especially in refractory cases. We also highlight the safety of novel JAK inhibitors, which can cause opportunistic infections, especially viral infections. Being a very recent therapeutic option, information regarding the safety of JAK inhibitors during pregnancy and for pediatric use is limited. However, it is recommended that JAK inhibitors should be avoided in pregnant and breastfeeding women. More clinical data, especially on highly selective inhibitors, are required to judge the efficacy and safety of JAK inhibition in CTDs.

Tofacitinib Ameliorates Lupus Through Suppression of T Cell Activation Mediated by TGF-Beta Type I Receptor

Autoreactive T cells play a crucial role in the pathogenesis of systemic lupus erythematosus (SLE). TGF-β type I receptor (TGFβRI) is pivotal in determining T cell activation. Here, we showed that TGFβRI expression in naïve CD4⁺ T cells was decreased in SLE patients, especially in those with high disease activity. Moreover, IL-6 was found to downregulate TGFβRI expression through JAK/STAT3 pathway in SLE patients. In vitro, the JAK inhibitor tofacitinib inhibited SLE T cell activating by upregulating TGFβRI expression in a dose-dependent manner. In MRL/lpr mice, tofacitinib treatment ameliorated the clinical indicators and lupus nephritis, as evidenced by reduced plasma anti-dsDNA antibody levels, decreased proteinuria, and lower renal histopathological score. Consistently, tofacitinib enhanced TGFβRI expression and inhibited T cell activation in vivo. TGFβRI inhibitor SB431542 reversed the effects of tofacitinib on T cell activation. Thus, our results have indicated that tofacitinib can suppress T cell activation by upregulating TGFβRI expression, which provides a possible molecular mechanism underlying clinical efficacy of tofacitinib in treating SLE patients.

Targeting Canonical and Non-Canonical STAT Signaling Pathways in Renal Diseases

Signal transducer and activator of transcription (STAT) plays an essential role in the inflammatory reaction and immune response of numerous renal diseases. STATs can transmit the signals of cytokines, chemokines, and growth factors from the cell membrane to the nucleus. In the canonical STAT signaling pathways, upon binding with their cognate receptors, cytokines lead to a caspase of Janus kinases (JAKs) and STATs tyrosine phosphorylation and activation. Besides receptor-associated tyrosine kinases JAKs, receptors with intrinsic tyrosine kinase activities, G-protein coupled receptors, and non-receptor tyrosine kinases can also activate STATs through tyrosine phosphorylation or, alternatively, other post-translational modifications. Activated STATs translocate into the nucleus and mediate the transcription of specific genes, thus mediating the progression of various renal diseases. Non-canonical STAT pathways consist of preassembled receptor complexes, preformed STAT dimers, unphosphorylated STATs (U-STATs), and non-canonical functions including mitochondria modulation, microtubule regulation and heterochromatin stabilization. Most studies targeting STAT signaling pathways have focused on canonical pathways, but research extending into non-canonical STAT pathways would provide novel strategies for treating renal diseases. In this review, we will introduce both canonical and non-canonical STAT pathways and their roles in a variety of renal diseases.

Case Report: Reversal of Long-Standing Refractory Diffuse Non-Scarring Alopecia Due to Systemic Lupus Erythematosus Following Treatment With Tofacitinib

The Janus kinases (JAKs) are intracellular tyrosine kinases involved in a broad variety of inflammatory cascades participating in the pathogenesis of systemic lupus erythematosus (SLE). Diffuse non-scarring alopecia is one of the most frequent cutaneous manifestations in SLE, resulting in devastating psychosocial consequences. Although recent studies have shown promising outcomes of the JAK inhibitors in SLE treatment, the efficacy of tofacitinib in diffuse non-scarring alopecia due to SLE has never been reported. Here we present a 29-year-old SLE patient with a 10-year history of refractory severe diffuse non-scarring alopecia who experienced dramatic hair regrowth with tofacitinib. Furthermore, we have made a systematic review regarding the potential effectiveness of tofacitinib in systemic and cutaneous lupus erythematosus. To the best of our knowledge, this is the first case study depicting an SLE patient with refractory alopecia who experienced impressive hair regrowth with the JAK1/3 inhibitor tofacitinib therapy, which contributes to expanding the field of possible uses of tofacitinib in SLE patients with difficult-to-treat cutaneous involvement, including severe alopecia.

The off-label uses profile of tofacitinib in systemic rheumatic diseases

Tofacitinib is an oral, small molecule JAK inhibitor that targets JAK1/JAK3. Tofacitinib has been approved by the FDA to be used in the treatments of rheumatoid arthritis, psoriatic arthritis, plaque psoriasis and ulcerative colitis. Considering the important pathogenic role of the JAK/STAT pathway in autoimmune disease, tofacitinib could be, theoretically, effective in the treatments of other systemic rheumatic diseases. Here we reviewed the published literature to profile the perspectives about the off-label uses of tofacitinib, especially in those refractory cases with poor response to conventional therapies or biologic agents. Tofacitinib can be a new therapeutic option and help reducing hormone dependence and correlated adverse events.

JAK/STAT signaling controls the fate of CD8+CD103+ tissue-resident memory T cell in lupus nephritis

Autoimmune mediated inflammation and renal damage in lupus nephritis (LN) depends partly on the infiltration of lymphocytes in glomeruli and renal interstitium. Here we identified a population of CD8⁺ T cells with a CD103⁺-phenotype in the healthy kidneys of human and mouse. These cells were typically CD69⁺CD103⁺ tissue-resident memory T cells (T_RM) in the kidney. CD8⁺ T_RM cells were expanded in the kidneys of patients with LN or MRL/lpr mice. The expansion of renal CD8⁺ T_RM cells correlated significantly with kidney disease activity. These cells were active in producing cytokines, perforin and granzyme B in the kidney of MRL/lpr mice. Importantly, renal CD8⁺ T_RM cells underwent proliferation and self-renewal to maintain a stable T_RM pool in the kidney of MRL/lpr mice, contributing to renal inflammation and damage. JAK/STAT signaling in the MRL/lpr mice was required for renal T_RM self-renewal as well as maintenance of effector functions. Targeting JAK/STAT signaling by tofacitinib effectively suppressed effector functions and impaired the survival of renal T_RM cells in the kidney, contributing to improved kidney function in MRL/lpr mice. These results provided evidences that renal CD8⁺ T_RM cells play a role in the pathogenesis of LN. They could serve as a therapeutic target for LN.

A Functional Landscape of CKD Entities From Public Transcriptomic Data

Introduction

To develop effective therapies and identify novel early biomarkers for chronic kidney disease, an understanding of the molecular mechanisms orchestrating it is essential. We here set out to understand how differences in chronic kidney disease (CKD) origin are reflected in gene expression. To this end, we integrated publicly available human glomerular microarray gene expression data for 9 kidney disease entities that account for most of CKD worldwide. Our primary goal was to demonstrate the possibilities and potential on data analysis and integration to the nephrology community.

Methods

We integrated data from 5 publicly available studies and compared glomerular gene expression profiles of disease with that of controls from nontumor parts of kidney cancer nephrectomy tissues. A major challenge was the integration of the data from different sources, platforms, and conditions that we mitigated with a bespoke stringent procedure.

Results

We performed a global transcriptome-based delineation of different kidney disease entities, obtaining a transcriptomic diffusion map of their similarities and differences based on the genes that acquire a consistent differential expression between each kidney disease entity and nephrectomy tissue. We derived functional insights by inferring the activity of signaling pathways and transcription factors from the collected gene expression data and identified potential drug candidates based on expression signature matching. We validated representative findings by immunostaining in human kidney biopsies indicating, for example, that the transcription factor FOXM1 is significantly and specifically expressed in parietal epithelial cells in rapidly progressive glomerulonephritis (RPGN) whereas not expressed in control kidney tissue. Furthermore, we found drug candidates by matching the signature on expression of drugs to that of the CKD entities, in particular, the Food and Drug Administration-approved drug nilotinib.

Conclusion

These results provide a foundation to comprehend the specific molecular mechanisms underlying different kidney disease entities that can pave the way to identify biomarkers and potential therapeutic targets. To facilitate further use, we provide our results as a free interactive Web application: https://saezlab.shinyapps.io/ckd_landscape/. However, because of the limitations of the data and the difficulties in its integration, any specific result should be considered with caution. Indeed, we consider this study rather an illustration of the value of functional genomics and integration of existing data.

Pathogenic and Therapeutic Relevance of JAK/STAT Signaling in Systemic Lupus Erythematosus: Integration of Distinct Inflammatory Pathways and the Prospect of Their Inhibition with an Oral Agent

Four Janus kinases (JAKs) (JAK1, JAK2, JAK3, TYK2) and seven signal transducers and activators of transcription (STATs) (STAT1, STAT2, STAT3, STAT4, STAT5A, STAT5B, STAT6) mediate the signal transduction of more than 50 cytokines and growth factors in many different cell types. Located intracellularly and downstream of cytokine receptors, JAKs integrate and balance the actions of various signaling pathways. With distinct panels of STAT-sensitive genes in different tissues, this highly heterogeneous system has broad in vivo functions playing a crucial role in the immune system. Thus, the JAK/STAT pathway is critical for resisting infection, maintaining immune tolerance, and enforcing barrier functions and immune surveillance against cancer. Breakdowns of this system and/or increased signal transduction may lead to autoimmunity and other diseases. Accordingly, the recent development and approval of the first small synthetic molecules targeting JAK molecules have opened new therapeutic avenues of potentially broad therapeutic relevance. Extensive data are now available regarding the JAK/STAT pathway in rheumatoid arthritis. Dysregulation of the cytokines is also a hallmark of systemic lupus erythematosus (SLE), and targeting the JAK/STAT proteins allows simultaneous suppression of multiple cytokines. Evidence from in vitro studies and animal models supports a pivotal role also in the pathogenesis of cutaneous lupus and SLE. This has important therapeutic implications, given the current paucity of targeted therapies especially in the latter. Herein, we summarize the currently available literature in experimental SLE, which has led to the recent promising Phase II clinical trial of a JAK inhibitor.

Tofacitinib Halts Progression of Graft Dysfunction in a Rat Model of Mixed Cellular and Humoral Rejection

BACKGROUND

The progression from acute to chronic antibody-mediated rejection in kidney transplant recipients is usually not prevented by current therapeutic options. Here, we investigated whether the use of tofacitinib (TOFA), a Janus kinase 3 inhibitor, was capable of preventing the progression of allograft dysfunction in a Fisher-to-Lewis rat model of kidney transplantation.

METHODS

Rats were treated from the third week after transplantation to allow the development of rejection. Treatment was based on cyclosporin A, rapamycin or TOFA. Renal function was assessed at 1, 4, 8, and 12 weeks after transplantation, whereas rat survival, histological lesions, and infiltrating lymphocytes were analyzed at 12 weeks.

RESULTS

Tofacitinib prolonged graft survival, preserved tubular and glomerular structures and reduced humoral damage characterized by C4d deposition. Tofacitinib was able to reduce donor-specific antibodies. In addition, T and natural killer cell graft infiltration was reduced in TOFA-treated rats. Although rapamycin-treated rats also showed prolonged graft survival, glomerular structures were more affected. Moreover, only TOFA treatment reduced the presence of T, B and natural killer cells in splenic parenchyma.

CONCLUSIONS

Tofacitinib is able to reduce the immune response generated in a rat model of kidney graft rejection, providing prolonged graft and recipient survival, better graft function, and less histological lesions.

Aberrant T Cell Signaling and Subsets in Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a chronic multi-organ debilitating autoimmune disease, which mainly afflicts women in the reproductive years. A complex interaction of genetics, environmental factors and hormones result in the breakdown of immune tolerance to "self" leading to damage and destruction of multiple organs, such as the skin, joints, kidneys, heart and brain. Both innate and adaptive immune systems are critically involved in the misguided immune response against self-antigens. Dendritic cells, neutrophils, and innate lymphoid cells are important in initiating antigen presentation and propagating inflammation at lymphoid and peripheral tissue sites. Autoantibodies produced by B lymphocytes and immune complex deposition in vital organs contribute to tissue damage. T lymphocytes are increasingly being recognized as key contributors to disease pathogenesis. CD4 T follicular helper cells enable autoantibody production, inflammatory Th17 subsets promote inflammation, while defects in regulatory T cells lead to unchecked immune responses. A better understanding of the molecular defects including signaling events and gene regulation underlying the dysfunctional T cells in SLE is necessary to pave the path for better management, therapy, and perhaps prevention of this complex disease. In this review, we focus on the aberrations in T cell signaling in SLE and highlight therapeutic advances in this field.

Overexpression of AGT promotes bronchopulmonary dysplasis via the JAK/STAT signal pathway

Angiotensinogen (AGT) is involved in the production of angiotensin II which is the main mediator of action of the rennin-angiotensin system (RAS), whereas the RAS mediates the regulation of sodium homeostasis, blood pressure, and inflammation. The present study aimed to investigate the roles of the AGT in the progression of broncopulmonary dysplasia in premature newborns. By bioinformatics analysis, AGT was found to be the major node in molecular interaction networks of BPD mouse model. Quantitative PCR and western blot analyses were applied to examine AGT expression in A549 cells which were treated with the hyperoxic condition. The AGT inhibitor Valsartan and the AGT agonist ANGII were employed to investigate the roles of AGT in cell growth and the inflammation. Results show that hyperoxic treatment induced upregulation of AGT expression in A549 cells. Overexpression of AGT resulted in the inflammation via the JAK/STAT signal pathway, ultimately suppressed the proliferation of the A549 cell. In conclusion, increased expression of AGT was demonstrated to be associated with the development and progression of BPD, and may be regarded as a promising therapeutic target for BPD.

Lupus nephritis and B-cell targeting therapy

INTRODUCTION

Lupus Nephritis (LN) is a severe manifestation of Systemic Lupus Erythematosus (SLE) with a significant prognostic impact. Over a prolonged course, an exhaustion of treatment alternatives may occur and further therapeutic options are needed. B cells play a pivotal role in disease pathogenesis and represent an attractive therapeutic target. Areas covered: This review provides an update regarding targeting B cells in LN. The rational for this approach, as well as currently available and future targets are discussed. Expert commentary: Despite its wide clinical use and the encouraging results from retrospective studies, a role of rituximab in LN has not been prospectively confirmed. Trial design methodologies as well as intrinsic limitations of this approach may be responsible and rituximab use is currently limited as a rescue treatment or in settings where a strong steroid sparing effect is warranted. Despite belimumab now being licensed for use in SLE, the evidence in LN is weak although prospective trials are on-going. The combination of different targeted approaches as well as a focus on new clinical end-points may be strategies to identify new therapeutic options.

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.