Proteasome inhibitors as experimental therapeutics of autoimmune diseases

Cell-specific gene networks and drivers in rheumatoid arthritis synovial tissues

Rheumatoid arthritis (RA) is a common autoimmune and inflammatory disease characterized by inflammation and hyperplasia of the synovial tissues. RA pathogenesis involves multiple cell types, genes, transcription factors (TFs) and networks. Yet, little is known about the TFs, and key drivers and networks regulating cell function and disease at the synovial tissue level, which is the site of disease. In the present study, we used available RNA-seq databases generated from synovial tissues and developed a novel approach to elucidate cell type-specific regulatory networks on synovial tissue genes in RA. We leverage established computational methodologies to infer sample-specific gene regulatory networks and applied statistical methods to compare network properties across phenotypic groups (RA versus osteoarthritis). We developed computational approaches to rank TFs based on their contribution to the observed phenotypic differences between RA and controls across different cell types. We identified 18 (fibroblast-like synoviocyte), 16 (T cells), 19 (B cells) and 11 (monocyte) key regulators in RA synovial tissues. Interestingly, fibroblast-like synoviocyte (FLS) and B cells were driven by multiple independent co-regulatory TF clusters that included MITF, HLX, BACH1 (FLS) and KLF13, FOSB, FOSL1 (B cells). However, monocytes were collectively governed by a single cluster of TF drivers, responsible for the main phenotypic differences between RA and controls, which included RFX5, IRF9, CREB5. Among several cell subset and pathway changes, we also detected reduced presence of Natural killer T (NKT) cells and eosinophils in RA synovial tissues. Overall, our novel approach identified new and previously unsuspected Key driver genes (KDG), TF and networks and should help better understanding individual cell regulation and co-regulatory networks in RA pathogenesis, as well as potentially generate new targets for treatment.

20S constitutive proteasome, 20S immunoproteasome, and cathepsin S are high-sensitivity and independent markers of immunological activity in relapsing-remitting type of multiple sclerosis

Research on the markers of autoimmune response in multiple sclerosis (MS) is still of great importance. The aim of our study was the evaluation of plasma 20S constitutive proteasome, 20S immunoproteasome, and cathepsin S concentrations as potential biomarkers of a relapsing-remitting type of MS (RRMS). Surface plasmon resonance imaging (SPRI) biosensors were used for the evaluation of protein concentrations. Plasma 20S constitutive proteasome, 20S immunoproteasome, and cathepsin S concentrations were significantly higher in RRMS patients compared to the control group. All three parameters were characterized by excellent usefulness in differentiating MS patients from healthy individuals (AUC equal to or close to 1.000). The plasma concentration of analyzed parameters was not correlated with severity of disability in the course of RRMS (EDSS value), the number of years from the first MS symptoms, the number of years from MS diagnosis, or the number of relapses within the 24-month observational period. Our study has shown that plasma concentrations of 20S constitutive proteasome, 20S immunoproteasome, and cathepsin S have promising potential in differentiating RRMS patients from healthy individuals. All of the analyzed parameters were found to be independent of the time of MS relapse and the severity of neurological symptoms. Hence, their potential as highly sensitive and independent circulating markers of RRMS suggests a stronger association with immunological activity (inflammatory processes) than with the severity of the disease.

Decoding the secrets: how conformational and structural regulators inhibit the human 20S proteasome

Acquired resistance to drugs that modulate specific protein functions, such as the human proteasome, presents a significant challenge in targeted therapies. This underscores the importance of devising new methodologies to predict drug binding and potential resistance due to specific protein mutations. In this work, we conducted an extensive computational analysis to ascertain the effects of selected mutations (Ala49Thr, Ala50Val, and Cys52Phe) within the active site of the human proteasome. Specifically, we sought to understand how these mutations might disrupt protein function either by altering protein stability or by impeding interactions with a clinical administered drug. Leveraging molecular dynamics simulations and molecular docking calculations, we assessed the effect of these mutations on protein stability and ligand affinity. Notably, our results indicate that the Cys52Phe mutation critically impacts protein-ligand binding, providing valuable insights into potential proteasome inhibitor resistance.

Clinical advances in immunotherapy for immune-mediated glomerular diseases

BACKGROUND AND OBJECTIVE

Due to the suboptimal therapeutic efficacy and potential adverse effects associated with traditional immunosuppressive medications, there has been an increasing emphasis on the development and utilization of immunotherapies. This paper aims to provide clinicians with valuable insights for selecting appropriate therapeutic approaches and contribute to the development of novel immunotherapeutic drugs.

MAIN BODY

This paper categorizes the immunotherapeutic drugs that are used for the treatment of immune-mediated glomerular diseases into three groups: immunotherapies targeting antigen-presenting cells (anti-CD80), immunotherapies targeting T/B cells (anti-CD20, anti-CD22, BAFF and APRIL inhibitors, CD40-CD40L inhibitors, proteasome inhibitors, Syk inhibitors, and Btk inhibitors), and immunotherapies targeting the complement system (C5 inhibitors, C5a/C5aR inhibitors, C3 inhibitors, MASP2 inhibitors, factor B inhibitors, and factor D inhibitors). The article then provides a comprehensive overview of advances related to these immunotherapeutic drugs in clinical research.

CONCLUSION

Certain immunotherapeutic drugs, such as rituximab, belimumab, and eculizumab, have exhibited notable efficacy in treating specific immune-mediated glomerular diseases, thereby providing novel therapeutic approaches for patients. Nonetheless, the efficacy of numerous immunotherapeutic drugs remains to be substantiated.

Targeting endothelial vascular cell adhesion molecule-1 in atherosclerosis: drug discovery and development of vascular cell adhesion molecule-1-directed novel therapeutics

Vascular cell adhesion molecule-1 (VCAM-1) has been well established as a critical contributor to atherosclerosis and consequently as an attractive therapeutic target for anti-atherosclerotic drug candidates. Many publications have demonstrated that disrupting the VCAM-1 function blocks monocyte infiltration into the sub-endothelial space, which effectively prevents macrophage maturation and foam cell transformation necessary for atherosclerotic lesion formation. Currently, most VCAM-1-inhibiting drug candidates in pre-clinical and clinical testing do not directly target VCAM-1 itself but rather down-regulate its expression by inhibiting upstream cytokines and transcriptional regulators. However, the pleiotropic nature of these regulators within innate immunity means that optimizing dosage to a level that suppresses pathological activity while preserving normal physiological function is extremely challenging and oftentimes infeasible. In recent years, highly specific pharmacological strategies that selectively inhibit VCAM-1 function have emerged, particularly peptide- and antibody-based novel therapeutics. Studies in such VCAM-1-directed therapies so far remain scarce and are limited by the constraints of current experimental atherosclerosis models in accurately representing the complex pathophysiology of the disease. This has prompted the need for a comprehensive review that recounts the evolution of VCAM-1-directed pharmaceuticals and addresses the current challenges in novel anti-atherosclerotic drug development.

Metabolic signature and proteasome activity controls synovial migration of CDC42hiCD14+ cells in rheumatoid arthritis

Objective

Activation of Rho-GTPases in macrophages causes inflammation and severe arthritis in mice. In this study, we explore if Rho-GTPases define the joint destination of pathogenic leukocytes, the mechanism by which they perpetuate rheumatoid arthritis (RA), and how JAK inhibition mitigates these effects.

Methods

CD14+ cells of 136 RA patients were characterized by RNA sequencing and cytokine measurement to identify biological processes and transcriptional regulators specific for CDC42 hiCD14+ cells, which were summarized in a metabolic signature (MetSig). The effect of hypoxia and IFN-γ signaling on the metabolic signature of CD14+ cells was assessed experimentally. To investigate its connection with joint inflammation, the signature was translated into the single-cell characteristics of CDC42 hi synovial tissue macrophages. The sensitivity of MetSig to the RA disease activity and the treatment effect were assessed experimentally and clinically.

Results

CDC42 hiCD14+ cells carried MetSig of genes functional in the oxidative phosphorylation and proteasome-dependent cell remodeling, which correlated with the cytokine-rich migratory phenotype and antigen-presenting capacity of these cells. Integration of CDC42 hiCD14+ and synovial macrophages marked with MetSig revealed the important role of the interferon-rich environment and immunoproteasome expression in the homeostasis of these pathogenic macrophages. The CDC42 hiCD14+ cells were targeted by JAK inhibitors and responded with the downregulation of immunoproteasome and MHC-II molecules, which disintegrated the immunological synapse, reduced cytokine production, and alleviated arthritis.

Conclusion

This study shows that the CDC42-related MetSig identifies the antigen-presenting CD14+ cells that migrate to joints to coordinate autoimmunity. The accumulation of CDC42 hiCD14+ cells discloses patients perceptive to the JAKi treatment.

New Scaffolds of Proteasome Inhibitors: Boosting Anticancer Potential by Exploiting the Synergy of In Silico and In Vitro Methodologies

Cancer is a complex multifactorial disease whose pathophysiology involves multiple metabolic pathways, including the ubiquitin-proteasome system, for which several proteasome inhibitors have already been approved for clinical use. However, the resistance to existing therapies and the occurrence of severe adverse effects is still a concern. The purpose of this study was the discovery of novel scaffolds of proteasome inhibitors with anticancer activity, aiming to overcome the limitations of the existing proteasome inhibitors. Thus, a structure-based virtual screening protocol was developed using the structure of the human 20S proteasome, and 246 compounds from virtual databases were selected for in vitro evaluation, namely proteasome inhibition assays and cell viability assays. Compound 4 (JHG58) was shortlisted as the best hit compound based on its potential in terms of proteasome inhibitory activity and its ability to induce cell death (both with IC50 values in the low micromolar range). Molecular docking studies revealed that compound 4 interacts with key residues, namely with the catalytic Thr1, Ala20, Thr21, Lys33, and Asp125 at the chymotrypsin-like catalytic active site. The hit compound is a good candidate for additional optimization through a hit-to-lead campaign.

Drug development and novel therapeutics to ensure a personalized approach in the treatment of systemic sclerosis

INTRODUCTION

Systemic sclerosis (SSc) is a systemic disease encompassing autoimmunity, vasculopathy, and fibrosis. SSc is still burdened by high mortality and morbidity rates. Recent advances in understanding the pathogenesis of SSc have identified novel potential therapeutic targets. Several clinical trials have been subsequently designed to evaluate the efficacy of a number of new drugs. The aim of this review is to provide clinicians with useful information about these novel molecules.

AREA COVERED

In this narrative review, we summarize the available evidence regarding the most promising targeted therapies currently under investigation for the treatment of SSc. These medications include kinase inhibitors, B-cell depleting agents, and interleukin inhibitors.

EXPERT OPINION

Over the next five years, several new, targeted drugs will be introduced in clinical practice for the treatment of SSc. Such pharmacological agents will expand the existing pharmacopoeia and enable a more personalized and effective approach to patients with SSc. Thus, it will not only possible to target a specific disease domain, but also different stages of the disease.

EULAR study group on ‘MHC-I-opathy’: identifying disease-overarching mechanisms across disciplines and borders

The ‘MHC-I (major histocompatibility complex class I)-opathy’ concept describes a family of inflammatory conditions with overlapping clinical manifestations and a strong genetic link to the MHC-I antigen presentation pathway. Classical MHC-I-opathies such as spondyloarthritis, Behçet’s disease, psoriasis and birdshot uveitis are widely recognised for their strong association with certain MHC-I alleles and gene variants of the antigen processing aminopeptidases ERAP1 and ERAP2 that implicates altered MHC-I peptide presentation to CD8+T cells in the pathogenesis. Progress in understanding the cause and treatment of these disorders is hampered by patient phenotypic heterogeneity and lack of systematic investigation of the MHC-I pathway.

Here, we discuss new insights into the biology of MHC-I-opathies that strongly advocate for disease-overarching and integrated molecular and clinical investigation to decipher underlying disease mechanisms. Because this requires transformative multidisciplinary collaboration, we introduce the EULAR study group on MHC-I-opathies to unite clinical expertise in rheumatology, dermatology and ophthalmology, with fundamental and translational researchers from multiple disciplines such as immunology, genomics and proteomics, alongside patient partners. We prioritise standardisation of disease phenotypes and scientific nomenclature and propose interdisciplinary genetic and translational studies to exploit emerging therapeutic strategies to understand MHC-I-mediated disease mechanisms. These collaborative efforts are required to address outstanding questions in the etiopathogenesis of MHC-I-opathies towards improving patient treatment and prognostication.

Reprograming of Gene Expression of Key Inflammatory Signaling Pathways in Human Peripheral Blood Mononuclear Cells by Soybean Lectin and Resveratrol

Inflammation is linked to several human diseases like microbial infections, cancer, heart disease, asthma, diabetes, and neurological disorders. We have shown that the prototype inflammatory agonist LPS modulates the activity of Ubiquitin-Proteasome System (UPS) and regulates transcription factors such as NF-κB, leading to inflammation, tolerance, hypoxia, autophagy, and apoptosis of cells. We hypothesized that proteasome modulators resveratrol and soybean lectin would alter the gene expression of mediators involved in inflammation-induced signaling pathways, when administered ex vivo to human peripheral blood mononuclear blood cells (PBMCs) obtained from normal healthy controls. To test this hypothesis, analysis of RNA derived from LPS-treated human PBMCs, with or without resveratrol and soybean lectin, was carried out using Next Generation Sequencing (NGS). Collectively, the findings described herein suggest that proteasome modulators, resveratrol (proteasome inhibitor) and lectins (proteasome activator), have a profound capacity to modulate cytokine expression in response to proteasome modulators, as well as expression of mediators in multiple signaling pathways in PBMCs of control subjects. We show for the first-time that resveratrol downregulates expression of mediators involved in several key signaling pathways IFN-γ, IL-4, PSMB8 (LMP7), and a subset of LPS-induced genes, while lectins induced IFN-γ, IL-4, PSMB8, and many of the same genes as LPS that are important for innate and adaptive immunity. These findings suggest that inflammation may be influenced by common dietary components and this knowledge may be used to prevent or reverse inflammation-based diseases.

Targeting inflammation and immune activation to improve CTLA4-Ig-based modulation of transplant rejection

For the last few decades, Calcineurin inhibitors (CNI)-based therapy has been the pillar of immunosuppression for prevention of organ transplant rejection. However, despite exerting effective control of acute rejection in the first year post-transplant, prolonged CNI use is associated with significant side effects and is not well suited for long term allograft survival. The implementation of Costimulation Blockade (CoB) therapies, based on the interruption of T cell costimulatory signals as strategy to control allo-responses, has proven potential for better management of transplant recipients compared to CNI-based therapies. The use of the biologic cytotoxic T-lymphocyte associated protein 4 (CTLA4)-Ig is the most successful approach to date in this arena. Following evaluation of the BENEFIT trials, Belatacept, a high-affinity version of CTLA4-Ig, has been FDA approved for use in kidney transplant recipients. Despite its benefits, the use of CTLA4-Ig as a monotherapy has proved to be insufficient to induce long-term allograft acceptance in several settings. Multiple studies have demonstrated that events that induce an acute inflammatory response with the consequent release of proinflammatory cytokines, and an abundance of allograft-reactive memory cells in the recipient, can prevent the induction of or break established immunomodulation induced with CoB regimens. This review highlights advances in our understanding of the factors and mechanisms that limit CoB regimens efficacy. We also discuss recent successes in experimentally designing complementary therapies that favor CTLA4-Ig effect, affording a better control of transplant rejection and supporting their clinical applicability.

Gene Ontology Analysis Highlights Biological Processes Influencing Non-Response to Anti-TNF Therapy in Rheumatoid Arthritis

Anti-TNF therapy has significantly improved disease control in rheumatoid arthritis, but a fraction of rheumatoid arthritis patients do not respond to anti-TNF therapy or lose response over time. Moreover, the mechanisms underlying non-response to anti-TNF therapy remain largely unknown. To date, many single biomarkers of response to anti-TNF therapy have been published but they have not yet been analyzed as a system of interacting nodes. The aim of our study is to systematically elucidate the biological processes underlying non-response to anti-TNF therapy in rheumatoid arthritis using the gene ontologies of previously published predictive biomarkers. Gene networks were constructed based on published biomarkers and then enriched gene ontology terms were elucidated in subgroups using gene ontology software tools. Our results highlight the novel role of proteasome-mediated protein catabolic processes (p = 2.91 × 10⁻¹⁵) and plasma lipoproteins (p = 4.55 × 10⁻¹¹) in anti-TNF therapy response. The results of our gene ontology analysis help elucidate the biological processes underlying non-response to anti-TNF therapy in rheumatoid arthritis and encourage further study of the highlighted processes.

Saquinavir: From HIV to COVID-19 and Cancer Treatment

Saquinavir was the first protease inhibitor developed for HIV therapy, and it changed the standard of treatment for this disease to a combination of drugs that ultimately led to increased survival of this otherwise deadly condition. Inhibiting the HIV protease impedes the virus from maturing and replicating. With this in mind, since the start of the COVID-19 outbreak, the research for already approved drugs (mainly antivirals) to repurpose for treatment of this disease has increased. Among the drugs tested, saquinavir showed promise in silico and in vitro in the inhibition of the SARS-CoV-2 main protease (3CLpro). Another field for saquinavir repurposing has been in anticancer treatment, in which it has shown effects in vitro and in vivo in several types of cancer, from Kaposi carcinoma to neuroblastoma, demonstrating cytotoxicity, apoptosis, inhibition of cell invasion, and improvement of radiosensibility of cancer cells. Despite the lack of follow-up in clinical trials for cancer use, there has been a renewed interest in this drug recently due to COVID-19, which shows similar pharmacological pathways and has developed superior in silico models that can be translated to oncologic research. This could help further testing and future approval of saquinavir repurposing for cancer treatment.

Tissue catabolism and donor-specific dexamethasone response in a human osteochondral model of post-traumatic osteoarthritis

BACKGROUND

Post-traumatic osteoarthritis (PTOA) does not currently have clinical prognostic biomarkers or disease-modifying drugs, though promising candidates such as dexamethasone (Dex) exist. Many challenges in studying and treating this disease stem from tissue interactions that complicate understanding of drug effects. We present an ex vivo human osteochondral model of PTOA to investigate disease effects on cartilage and bone homeostasis and discover biomarkers for disease progression and drug efficacy.

METHODS

Human osteochondral explants were harvested from normal (Collins grade 0-1) ankle talocrural joints of human donors (2 female, 5 male, ages 23-70). After pre-equilibration, osteochondral explants were treated with a single-impact mechanical injury and TNF-α, IL-6, and sIL-6R ± 100 nM Dex for 21 days and media collected every 2-3 days. Chondrocyte viability, tissue DNA content, and glycosaminoglycan (sGAG) percent loss to the media were assayed and compared to untreated controls using a linear mixed effects model. Mass spectrometry analysis was performed for both cartilage tissue and pooled culture medium, and the statistical significance of protein abundance changes was determined with the R package limma and empirical Bayes statistics. Partial least squares regression analyses of sGAG loss and Dex attenuation of sGAG loss against proteomic data were performed.

RESULTS

Injury and cytokine treatment caused an increase in the release of matrix components, proteases, pro-inflammatory factors, and intracellular proteins, while tissue lost intracellular metabolic proteins, which was mitigated with the addition of Dex. Dex maintained chondrocyte viability and reduced sGAG loss caused by injury and cytokine treatment by 2/3 overall, with donor-specific differences in the sGAG attenuation effect. Biomarkers of bone metabolism had mixed effects, and collagen II synthesis was suppressed with both disease and Dex treatment by 2- to 5-fold. Semitryptic peptides associated with increased sGAG loss were identified. Pro-inflammatory humoral proteins and apolipoproteins were associated with lower Dex responses.

CONCLUSIONS

Catabolic effects on cartilage tissue caused by injury and cytokine treatment were reduced with the addition of Dex in this osteochondral PTOA model. This study presents potential peptide biomarkers of early PTOA progression and Dex efficacy that can help identify and treat patients at risk of PTOA.

B cells in autoimmune hepatitis: bystanders or central players?

B cells are central for the adaptive immune system to mount successful immune responses not only as antibody producers but also as regulators of cellular immunity. These multifaceted features are also reflected in autoimmunity where autoreactive B cells can fuel disease by production of cytotoxic autoantibodies, presentation of autoantigens to autoreactive T cells, and secretion of cytokines and chemokines that either promote detrimental immune activation or impair regulatory T and B cells. The role of B cells and autoantibodies in autoimmune hepatitis (AIH) have been controversially discussed, with typical autoantibodies and hypergammaglobulinemia indicating a key role, while strong HLA class II association suggests T cells as key players. In this review, we summarize current knowledge on B cells in AIH and how different B cell subpopulations may drive AIH progression beyond autoantibodies. We also discuss recent findings of B cell-directed therapies in AIH.

Novel treatment strategies for acetylcholine receptor antibody-positive myasthenia gravis and related disorders

The presence of autoantibodies directed against the muscle nicotinic acetylcholine receptor (AChR) is the most common cause of myasthenia gravis (MG). These antibodies damage the postsynaptic membrane of the neuromuscular junction and cause muscle weakness by depleting AChRs and thus impairing synaptic transmission. As one of the best-characterized antibody-mediated autoimmune diseases, AChR-MG has often served as a reference model for other autoimmune disorders. Classical pharmacological treatments, including broad-spectrum immunosuppressive drugs, are effective in many patients. However, complete remission cannot be achieved in all patients, and 10% of patients do not respond to currently used therapies. This may be attributed to production of autoantibodies by long-lived plasma cells which are resistant to conventional immunosuppressive drugs. Hence, novel therapies specifically targeting plasma cells might be a suitable therapeutic approach for selected patients. Additionally, in order to reduce side effects of broad-spectrum immunosuppression, targeted immunotherapies and symptomatic treatments will be required. This review presents established therapies as well as novel therapeutic approaches for MG and related conditions, with a focus on AChR-MG.

Modulating the Ubiquitin–Proteasome System: A Therapeutic Strategy for Autoimmune Diseases

Multiple sclerosis (MS) is an autoimmune, neurodegenerative disease associated with the central nervous system (CNS). Autoimmunity is caused by an abnormal immune response to self-antigens, which results in chronic inflammation and tissue death. Ubiquitination is a post-translational modification in which ubiquitin molecules are attached to proteins by ubiquitinating enzymes, and then the modified proteins are degraded by the proteasome system. In addition to regulating proteasomal degradation of proteins, ubiquitination also regulates other cellular functions that are independent of proteasomal degradation. It plays a vital role in intracellular protein turnover and immune signaling and responses. The ubiquitin–proteasome system (UPS) is primarily responsible for the nonlysosomal proteolysis of intracellular proteins. The 26S proteasome is a multicatalytic adenosine-triphosphate-dependent protease that recognizes ubiquitin covalently attached to particular proteins and targets them for degradation. Damaged, oxidized, or misfolded proteins, as well as regulatory proteins that govern many essential cellular functions, are removed by this degradation pathway. When this system is affected, cellular homeostasis is altered, resulting in the induction of a range of diseases. This review discusses the biochemistry and molecular biology of the UPS, including its role in the development of MS and proteinopathies. Potential therapies and targets involving the UPS are also addressed.

Immunoproteasome Activity in Chronic Lymphocytic Leukemia as a Target of the Immunoproteasome-Selective Inhibitors

Targeting proteasome with proteasome inhibitors (PIs) is an approved treatment strategy in multiple myeloma that has also been explored pre-clinically and clinically in other hematological malignancies. The approved PIs target both the constitutive and the immunoproteasome, the latter being present predominantly in cells of lymphoid origin. Therapeutic targeting of the immunoproteasome in cells with sole immunoproteasome activity may be selectively cytotoxic in malignant cells, while sparing the non-lymphoid tissues from the on-target PIs toxicity. Using activity-based probes to assess the proteasome activity profile and correlating it with the cytotoxicity assays, we identified B-cell chronic lymphocytic leukemia (B-CLL) to express predominantly immunoproteasome activity, which is associated with high sensitivity to approved proteasome inhibitors and, more importantly, to the immunoproteasome selective inhibitors LU005i and LU035i, targeting all immunoproteasome active subunits or only the immunoproteasome β5i, respectively. At the same time, LU102, a proteasome β2 inhibitor, sensitized B-CLL or immunoproteasome inhibitor-inherently resistant primary cells of acute myeloid leukemia, B-cell acute lymphoblastic leukemia, multiple myeloma and plasma cell leukemia to low doses of LU035i. The immunoproteasome thus represents a novel therapeutic target, which warrants further testing with clinical stage immunoproteasome inhibitors in monotherapy or in combinations.

NF-κB Signaling and Inflammation-Drug Repurposing to Treat Inflammatory Disorders?

NF-κB is a central mediator of inflammation, response to DNA damage and oxidative stress. As a result of its central role in so many important cellular processes, NF-κB dysregulation has been implicated in the pathology of important human diseases. NF-κB activation causes inappropriate inflammatory responses in diseases including rheumatoid arthritis (RA) and multiple sclerosis (MS). Thus, modulation of NF-κB signaling is being widely investigated as an approach to treat chronic inflammatory diseases, autoimmunity and cancer. The emergence of COVID-19 in late 2019, the subsequent pandemic and the huge clinical burden of patients with life-threatening SARS-CoV-2 pneumonia led to a massive scramble to repurpose existing medicines to treat lung inflammation in a wide range of healthcare systems. These efforts continue and have proven to be controversial. Drug repurposing strategies are a promising alternative to de novo drug development, as they minimize drug development timelines and reduce the risk of failure due to unexpected side effects. Different experimental approaches have been applied to identify existing medicines which inhibit NF-κB that could be repurposed as anti-inflammatory drugs.

Natural products are an important source for proteasome regulating agents

BACKGROUND

Natural medicines have a long history in the prevention and treatment of various diseases in East Asian region, especially in China. Modern research has proved that the pharmacological effects of numerous natural medicines involve the participation of ubiquitin proteasome system (UPS). UPS can degrade the unwanted and damaged proteins widely distributed in the nucleus and cytoplasm of various eukaryotes.

PURPOSE

The objective of the present study was to review and discuss the regulatory effects of natural products and extracts on proteasome components, which may help to find new proteasome regulators for drug development and clinical applications.

METHODS

The related information was compiled using the major scientific databases, such as CNKI, Elsevier, ScienceDirect, PubMed, SpringerLink, Wiley Online, and GeenMedical. The keywords "natural product" and "proteasome" were applied to extract the literature. Nature derived extracts, compounds and their derivatives involved in proteasome regulation were included, and the publications related to synthetic proteasome agents were excluded.

RESULTS

The pharmacological effects of more than 80 natural products and extracts derived from phytomedicines related to the proteasome regulation were reviewed. These natural products were classified according to their chemical properties. We also summarized some laws of action of natural products as proteasome regulators in the treatment of diseases, and listed the action characteristics of the typical natural products.

CONCLUSION

Natural products derived from nature can induce the degradation of damaged proteins through UPS or act as regulators to directly regulate the activity of proteasome. But few proteasome modulators are applied clinically. Summary of known rules for proteasome modulators will contribute to discover, modify and synthesize more proteasome modulators for clinical applications.

Delanzomib, a Novel Proteasome Inhibitor, Combined With Adalimumab Drastically Ameliorates Collagen-Induced Arthritis in Rats by Improving and Prolonging the Anti-TNF-α Effect of Adalimumab

Delanzomib is a novel proteasome inhibitor initially developed for treating multiple myeloma. It was found to inhibit the expression of tumor necrosis factor alpha (TNF-α). This study aimed to investigate the ameliorating effect of delanzomib on collagen-induced arthritis (CIA) and to explore the pharmacodynamics and pharmacokinetics (PK) interactions between delanzomib and adalimumab. Rats with CIA were randomly assigned to receive the treatment with delanzomib, adalimumab, delanzomib combined with adalimumab, or placebo. Visual inspection and biochemical examinations including TNF-α, interleukin 6, and C-reactive protein were performed to assess arthritis severity during the treatment. The adalimumab concentration in rats was determined to evaluate the PK interaction between delanzomib and adalimumab. Also, the levels of neonatal Fc receptor (FcRn) and FcRn mRNA were measured to explore the role of FcRn in the PK interaction between delanzomib and adalimumab. As a result, delanzomib combined with adalimumab exhibited stronger anti-arthritis activity than a single drug because both drugs synergistically reduced TNF-α level in vivo. Delanzomib also decreased adalimumab elimination in rats by increasing the level of FcRn. The slower elimination of adalimumab in rats further prolonged the anti-TNF-α effect of adalimumab. Moreover, FcRn level was increased by delanzomib via suppressing FcRn degradation rather than promoting FcRn production. In conclusion, delanzomib combined with adalimumab may be a potential therapeutic approach for treating rheumatoid arthritis. The initial finding that the PK interaction occurred between delanzomib and adalimumab may have clinical relevance for patients who simultaneously take proteasome inhibitors and anti-TNF-α therapeutic proteins.

Dose-dependent immunomodulatory effects of bortezomib in experimental autoimmune neuritis

Proteasome inhibition with bortezomib has been reported to exert an immunomodulatory action in chronic autoimmune neuropathies. However, bortezomib used for the treatment of multiple myeloma induces a painful toxic polyneuropathy at a higher concentration. Therefore, we addressed this controversial effect and evaluated the neurotoxic and immunomodulatory mode of action of bortezomib in experimental autoimmune neuritis. Bortezomib-induced neuropathy was investigated in Lewis rats using the von Frey hair test, electrophysiological, qPCR and histological analyses of the sciatic nerve as well as dorsal root ganglia outgrowth studies. The immunomodulatory potential of bortezomib was characterized in Lewis rats after experimental autoimmune neuritis induction with P2_53-78 peptide. Clinical, electrophysiological, histological evaluation, von Frey hair test, flow cytometric and mRNA analyses were used to unravel the underlying mechanisms. We defined the toxic concentration of 0.2 mg/kg bortezomib applied intraperitoneally at Days 0, 4, 8 and 12. This dosage induces a painful toxic neuropathy but preserves axonal regeneration in vitro. Bortezomib at a concentration of 0.05 mg/kg significantly ameliorated experimental autoimmune neuritis symptoms, improved experimental autoimmune neuritis-induced hyperalgesia and nerve conduction studies, and reduced immune cell infiltration. Furthermore, proteasome inhibition induced a transcriptional downregulation of Nfkb in the sciatic nerve, while its inhibitor Ikba (also known as Nfkbia) was upregulated. Histological analyses of bone marrow tissue revealed a compensatory increase of CD138⁺ plasma cells. Our data suggest that low dose bortezomib (0.05 mg/kg intraperitoneally) has an immunomodulatory effect in the context of experimental autoimmune neuritis through proteasome inhibition and downregulation of nuclear factor 'kappa-light-chain-enhancer' of activated B-cells (NFKB). Higher bortezomib concentrations (0.2 mg/kg intraperitoneally) induce sensory neuropathy; however, the regeneration potential remains unaffected. Our data empathizes that bortezomib may serve as an attractive treatment option for inflammatory neuropathies in lower concentrations.

Etodolac improves collagen induced rheumatoid arthritis in rats by inhibiting synovial inflammation, fibrosis and hyperplasia

Synovial hyperplasia is the main cause of chronic rheumatoid arthritis (RA), but the mechanism of synovial hyperplasia is still unclear. Etodolac (ETD) is a selective COX-2 inhibitor for relieving pain and stiffness in RA, but the disease modifying effect is still lack of evidence. Proteomics method was used to study the differential proteome of synovial tissue in collagen induced arthritis (CIA) in rats. With the help of STRING analysis, the upregulated proteins enriched in the cluster of complement and coagulation cascades and platelet degranulation were highlighted, these proteins with fibrogenic factors Lum, CIV, CXI and Tgfbi participated in the synovial inflammation, fibrosis and hyperplasia in CIA. Based on KOG function class analysis, the proteins involved in the events of the central dogma was explored. They might be hyperplasia related proteins for most of them are related to the proliferation of cancer. ETD significantly attenuated synovial inflammation, fibrosis and hyperplasia in CIA rats by downregulating these proteins. Several proteins have not been observed in RA so far, such as Tmsb4x, Pura, Nfic, Ruvbl1, Snrpd3, U2af2, Srrm2, Srsf7, Elavl1, Hnrnph1, Wars, Yars, Bzw2, Mcts1, Eif4b, Ctsh, Lamp1, Dpp7, Ptges3, Cdc37 and Septin9, they might be potentials targets for RA. Blood biochemistry tests showed the safety of 7 months use of ETD on rats. In conclusion, present study displayed a comprehensive mechanism of synovial hyperplasia in CIA rats, on this basis, the clinical value of ETD in the treatment of RA was well confirmed.

Trajectory mapping of primary Sjögren's syndrome via transcriptome learning demonstrates limitations of peripheral blood sequencing

Primary Sjögren's syndrome (pSS) is a complex autoimmune disease characterized by aberrant immune cell action against secretory glands throughout the body. A number of studies have previously identified unique characteristics in the circulating expression profile of white blood cells of pSS patients. However, the molecular progression pattern of pSS is unclear. Through a systematic analysis of pSS transcriptome information, we found that pSS transcriptomes display broad heterogeneity, but cannot be distinguished from the broad range of possible profiles of healthy controls. Instead, only sample learning using a subset of pre-identified signature genes could achieve partial separation through a trajectory governed by interferon activity. Interestingly, this trajectory is correlated with a decrease in dendritic cell counts. Our study thus highlights a major limitation to the utility of broad blood transcriptome analysis in the context of pSS, while also identifying several factors that influence the divergence between patient samples.

Nostocyclopeptides as New Inhibitors of 20S Proteasome

Nostocyclopeptides (Ncps) are a small class of bioactive nonribosomal peptides produced solely by cyanobacteria of the genus Nostoc. In the current work, six Ncps were isolated from Nostoc edaphicum strain CCNP1411. The bioactivity of these compounds was tested in vitro against 20S proteasome, a proteolytic complex that plays an important role in maintaining cellular proteostasis. Dysfunction of the complex leads to many pathological disorders. The assays indicated selective activity of specific Ncp variants. For two linear peptide aldehydes, Ncp-A2-L and Ncp-E2-L, the inhibitory effects on chymotrypsin-like activity were revealed, while the cyclic variant, Ncp-A2, inactivated the trypsin-like site of this enzymatic complex. The aldehyde group was confirmed to be an important element of the chymotrypsin-like activity inhibitors. The nostocyclopeptides, as novel inhibitors of 20S proteasome, increased the number of natural products that can be considered potential regulators of cellular processes.

Using multiple Mendelian randomization approaches and genetic correlations to understand obesity, urate, and gout

Observational studies suggest relationships between obesity, urate, and gout but are possibly confounded. We assessed whether genetically determined obesity, higher urate (and related traits), and gout were causal using multiple Mendelian randomization (MR) approaches and linkage disequilibrium score regression for genetic correlations (rg). For data, we used genome-wide association study summary statistics available through MR-Base. We observed that obesity increased urate (beta = 0.127; 95% CI = 0.098, 0.157; P-value = 1.2E-17; rg = 0.25 [P-value = 0.001]) and triglycerides (beta = 0.082; 95% CI = 0.065, 0.099; P-value = 1.2E-21; rg = 0.23 [P-value = 8.8E-12]) and decreased high-density lipoprotein cholesterol (HDL) (beta = - 0.083; 95% CI = - 0.101, - 0.065; P-value = 2.5E-19; rg = - 0.28; [P-value = 5.2E-24]). Higher triglycerides increased urate (beta = 0.198; 95% CI = 0.146, 0.251; P-value = 8.9E-14; rg = 0.29 [P-value = 0.001]) and higher HDL decreased urate (beta = - 0.109; 95% CI = - 0.148, - 0.071; P-value = 2.7E- 08; rg = - 0.21 [P-value = 9.8E-05]). Higher urate (OR = 1.030; 95% CI = 1.028, 1.032; P-value = 1.1E-130; rg = 0.89 [P-value = 1.7E-55]) and obesity caused gout (OR = 1.003; 95% CI = 1.001, 1.004; P-value = 1.3E-04; rg = 0.23 [P-value = 2.7E-05]). Obesity on gout with urate as a mediator revealed all the effect of obesity on gout occurred through urate. Obesity on low-density lipoprotein cholesterol (LDL) was null (beta = -0.011; 95% CI = -0.030, 0.008; P-value = 2.6E-01; rg = 0.03 [P-value = 0.369]). A multivariable MR of obesity, HDL, and triglycerides on urate showed obesity influenced urate when accounting for HDL and triglycerides. Obesity's impact on urate was exacerbated by it decreasing HDL.

Bortezomib: a proteasome inhibitor for the treatment of autoimmune diseases

Autoimmune diseases (ADs) are conditions in which the immune system cannot distinguish self from non-self and, as a result, tissue injury occurs primarily due to the action of various inflammatory mediators. Different immunosuppressive agents are used for the treatment of patients with ADs, but some clinical cases develop resistance to currently available therapies. The proteasome inhibitor bortezomib (BTZ) is an approved agent for first-line therapy of people with multiple myeloma. BTZ has been shown to improve the symptoms of different ADs in animal models and ameliorated symptoms in patients with systemic lupus erythematous, rheumatoid arthritis, myasthenia gravis, neuromyelitis optica spectrum disorder, Chronic inflammatory demyelinating polyneuropathy, and autoimmune hematologic diseases that were nonresponsive to conventional therapies. Proteasome inhibition provides a potent strategy for treating ADs. BTZ represents a proteasome inhibitor that can potentially be used to treat AD patients resistant to conventional therapies.

Discovery of selective fragment-sized immunoproteasome inhibitors

Proteasomes contribute to maintaining protein homeostasis and their inhibition is beneficial in certain types of cancer and in autoimmune diseases. However, the inhibition of the proteasomes in healthy cells leads to unwanted side-effects and significant effort has been made to identify inhibitors specific for the immunoproteasome, especially to treat diseases which manifest increased levels and activity of this proteasome isoform. Here, we report our efforts to discover fragment-sized inhibitors of the human immunoproteasome. The screening of an in-house library of structurally diverse fragments resulted in the identification of benzo[d]oxazole-2(3H)-thiones, benzo[d]thiazole-2(3H)-thiones, benzo[d]imidazole-2(3H)-thiones, and 1-methylbenzo[d]imidazole-2(3H)-thiones (with a general term benzoXazole-2(3H)-thiones) as inhibitors of the chymotrypsin-like (β5i) subunit of the immunoproteasome. A subsequent structure-activity relationship study provided us with an insight regarding growing vectors. Binding to the β5i subunit was shown and selectivity against the β5 subunit of the constitutive proteasome was determined. Thorough characterization of these compounds suggested that they inhibit the immunoproteasome by forming a disulfide bond with the Cys48 available specifically in the β5i active site. To obtain fragments with biologically more tractable covalent interactions, we performed a warhead scan, which yielded benzoXazole-2-carbonitriles as promising starting points for the development of selective immunoproteasome inhibitors with non-peptidic scaffolds.

The clinical efficacy of Rituximab administration in autoimmunity disorders, primary immunodeficiency diseases and malignancies

Rituximab (RTX), as a monoclonal antibody-based immunotherapeutic intervention targeting CD20 on B cells, has proven efficacy in the treatment of patients with some immune-mediated diseases. In the present review, we provided information on the immunobiological mechanisms of signaling for RTX and its clinical applications, according to the immune-pathophysiology involved in the microenvironment of multiple diseases. We highlighted combination therapy, dose schedules, and laboratory monitoring, as well as the associated common and rare side effects to avoid. We also discussed the efficacy and safety of RTX-based therapeutic strategies and whether RTX therapy can be used as a promising treatment regimen for autoimmune diseases, primary immunodeficiency diseases, and malignancies. Our review highlights and supports the importance of collaboration between basic medical researchers and clinical specialists when considering the use of RTX in the treatment of various immune-mediated disorders.

Synthesis and Biochemical Evaluation of Warhead-Decorated Psoralens as (Immuno)Proteasome Inhibitors

The immunoproteasome is a multicatalytic protease that is predominantly expressed in cells of hematopoietic origin. Its elevated expression has been associated with autoimmune diseases, various types of cancer, and inflammatory diseases. Selective inhibition of its catalytic activities is therefore a viable approach for the treatment of these diseases. However, the development of immunoproteasome-selective inhibitors with non-peptidic scaffolds remains a challenging task. We previously reported 7H-furo[3,2-g]chromen-7-one (psoralen)-based compounds with an oxathiazolone warhead as selective inhibitors of the chymotrypsin-like (β5i) subunit of immunoproteasome. Here, we describe the influence of the electrophilic warhead variations at position 3 of the psoralen core on the inhibitory potencies. Despite mapping the chemical space with different warheads, all compounds showed decreased inhibition of the β5i subunit of immunoproteasome in comparison to the parent oxathiazolone-based compound. Although suboptimal, these results provide crucial information about structure–activity relationships that will serve as guidance for the further design of (immuno)proteasome inhibitors.

Proteasome inhibitors reduce thrombospondin-1 release in human dysferlin-deficient myotubes

Background

Dysferlinopathies are a group of muscle disorders causing muscle weakness and absence or low levels of dysferlin, a type-II transmembrane protein and the causative gene of these dystrophies. Dysferlin is implicated in vesicle fusion, trafficking, and membrane repair. Muscle biopsy of patients with dysferlinopathy is characterized by the presence of inflammatory infiltrates. Studies in the muscle of both human and mouse models of dysferlinopathy suggest dysferlin deficient muscle plays a role in this inflammation by releasing thrombospondin-1. It has also been reported that vitamin D3 treatment enhances dysferlin expression. The ubiquitin-proteasome system recognizes and removes proteins that fail to fold or assemble properly and previous studies suggest that its inhibition could have a therapeutic effect in muscle dystrophies. Here we assessed whether inhibition of the ubiquitin proteasome system prevented degradation of dysferlin in immortalized myoblasts from a patients with two missense mutations in exon 44.

Methods

To assess proteasome inhibition we treated dysferlin deficient myotubes with EB1089, a vitamin D3 analog, oprozomib and ixazomib. Western blot was performed to analyze the effect of these treatments on the recovery of dysferlin and myogenin expression. TSP-1 was quantified using the enzyme-linked immunosorbent assay to analyze the effect of these drugs on its release. A membrane repair assay was designed to assess the ability of treated myotubes to recover after membrane injury and fusion index was also measured with the different treatments. Data were analyzed using a one-way ANOVA test followed by Tukey post hoc test and analysis of variance. A p ≤ 0.05 was considered statistically significant.

Results

Treatment with proteasome inhibitors and EB1089 resulted in a trend towards an increase in dysferlin and myogenin expression. Furthermore, EB1089 and proteasome inhibitors reduced the release of TSP-1 in myotubes. However, no effect was observed on the repair of muscle membrane after injury.

Conclusions

Our findings indicate that the ubiquitin-proteasome system might not be the main mechanism of mutant dysferlin degradation. However, its inhibition could help to improve muscle inflammation by reducing TSP-1 release.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-020-03756-7.

Substituted Imidazoline Synthesis: A Diastereo- and Enantioselective aza-Henry Route to a Human Proteasome Modulator

The first enantio- and diastereoselective synthesis of Tepe's human proteasome modulator is described. Routes to this and other highly substituted chiral imidazolines generally produce racemic material. Key to the route disclosed here is a gram-scale anti-selective aza-Henry reaction of an α-alkyl α-nitro ester nucleophile, catalyzed by a Bis(Amidine) [BAM] chiral proton complex, delivering the key intermediate in high yield as a single stereoisomer. The adduct is reduced to the amino ester and converted to an imidazoline.

Salinosporamide A, a Marine-Derived Proteasome Inhibitor, Inhibits T Cell Activation through Regulating Proliferation and the Cell Cycle

The appropriate regulation of T cell activity under inflammatory conditions is crucial for maintaining immune homeostasis. Salinosporamide A discovered as a self-resistance product from the marine bacterium Salinospora tropica, has been used as a potent proteasome inhibitor (PI). Although PIs have been developed as novel therapeutics for autoimmune diseases, due to their immunosuppressive effect, whether salinosporamide A inhibits T cell activation remains unknown. The current study finds that salinosporamide A is not cytotoxic, but controls T cell proliferation. Results from our cell cycle arrest analysis revealed that salinosporamide A leads to cell cycle arrest and regulates the expression of cyclin-dependent kinases. Under activated conditions, salinosporamide A abrogated T cell activation by T cell receptor-mediated stimulation, in which the production of cytokines was inhibited by pretreatment with salinosporamide A. Furthermore, we demonstrated that the regulation of T cell activation by salinosporamide A is mediated by suppressing the MAPK pathway. Therefore, our results suggest that salinosporamide A effectively suppresses T cell activation through regulating T cell proliferation and the cell cycle and provides great insight into the development of novel therapeutics for autoimmune diseases or graft-versus-host disease.

From Cancer to Immune-Mediated Diseases and Tolerance Induction: Lessons Learned From Immune Oncology and Classical Anti-cancer Treatment

Success in cancer treatment over the last four decades has ranged from improvements in classical drug therapy to immune oncology. Anti-cancer drugs have also often proven beneficial for the treatment of inflammatory and autoimmune diseases. In this review, we report on challenging examples that bridge between treatment of cancer and immune-mediated diseases, addressing mechanisms and experimental models as well as clinical investigations. Patient-derived tumor xenograft (PDX) (humanized) mouse models represent useful tools for preclinical evaluation of new therapies and biomarker identification. However, new developments using human ex vivo approaches modeling cancer, for example in microfluidic human organs-on-chips, promise to identify key molecular, cellular and immunological features of human cancer progression in a fully human setting. Classical drugs which bridge the gap, for instance, include cytotoxic drugs, proteasome inhibitors, PI3K/mTOR inhibitors and metabolic inhibitors. Biologicals developed for cancer therapy have also shown efficacy in the treatment of autoimmune diseases. In immune oncology, redirected chimeric antigen receptor (CAR) T cells have achieved spectacular remissions in refractory B cell leukemia and lymphoma and are currently under development for tolerance induction using cell-based therapies such as CAR Tregs or NK cells. Finally, a brief outline will be given of the lessons learned from bridging cancer and autoimmune diseases as well as tolerance induction.

Autoimmune encephalitis and immune therapy: lessons from Argentina

Autoimmune encephalitis (AE) is a common cause of noninfectious acute encephalitis. We aimed to provide the first review of immune therapy regimens used for patients with AE in Latin America, as well as the safety and efficacy associated with them, by reviewing the medical records of Argentine patients with AE treated between 2013 and 2018. Data included clinical symptoms, laboratory tests, electroencephalography, magnetic resonance imaging, cerebral spinal fluid, and neoplasm screenings. We examined ten AE patients who received first-line immunotherapy at a median of 2.5 months following symptom onset. Among these patients, five required second-line treatment: three received therapy at a median of 4 months (2-112) after symptom onset and were treated with rituximab, while two received therapy at a median of 4.5 (4-5) months after onset and received methylprednisolone for 6 months and initiated chronic treatment with azathioprine. By the last follow-up, their respective outcomes improved significantly. On the modified Rankin Scale, the median score decreased from 5 to 1 (p ≤ 0.05). Only two of the ten patients in our series experienced relapses; both had been treated with a combination of methylprednisolone and IVIG. The regimen after recurrence included rituximab and corticoids plus azathioprine. Neither patient had experienced another relapse by their last follow-up. Our findings demonstrate the importance of early and aggressive immunosuppressive therapy to achieve a good clinical outcome and a fast recovery without relapses.

Early Bortezomib Therapy for Refractory Anti-NMDA Receptor Encephalitis

Introduction: Anti-N-methyl-D-aspartate (NMDA) receptor encephalitis is an increasingly recognized form of immune-mediated encephalitis. Here we present a case that represents the shortest hospitalization-to-bortezomib treatment timeline (42 days), and we believe that this is reflected in the patient's outcome with complete independence within a short timeframe.

Case Report: We describe a case of anti-NMDA receptor encephalitis in an 18-year-old African American female presenting with progressive, medically refractory disease. Despite two rounds of high-dose intravenous steroids, plasma exchange, immunoglobulin administration, and rituximab for B-cell depletion, the patient failed to respond by hospital day 42 and received off-label use of the proteasome inhibitor bortezomib. During the 15 days after the bortezomib administration, the patient showed dramatic neurologic recovery that allowed her transfer out of the intensive care unit. At follow-up after 1-month, the patient reported feeling normal cognitively and showed dramatic improvement in cognitive scores.

Conclusion: This case and literature review provide preliminary evidence that early treatment of anti-NMDA receptor encephalitis with the proteasome inhibitor bortezomib appears safe and tolerable. However, randomized trials are needed to show the efficacy and the long-term benefit.

Unraveling the mysteries of plasma cells

Antibody-secreting plasma cells are the central pillars of humoral immunity. They are generated in a fundamental cellular restructuring process from naive B cells upon contact with antigen. This outstanding process is guided and controlled by a complex transcriptional network accompanied by a fascinating morphological metamorphosis, governed by the combined action of Blimp-1, Xbp-1 and IRF-4. The survival of plasma cells requires the intimate interaction with a specific microenvironment, consisting of stromal cells and cells of hematopoietic origin. Cell-cell contacts, cytokines and availability of metabolites such as glucose and amino acids modulate the survival abilities of plasma cells in their niches. Moreover, plasma cells have been shown to regulate immune responses by releasing cytokines. Furthermore, plasma cells are central players in autoimmune diseases and malignant transformation of plasma cells can result in the generation of multiple myeloma. Hence, the development of sophisticated strategies to deplete autoreactive plasma cells and myeloma cells represents a challenge for current and future research.

Bortezomib-Responsive Refractory Anti-N-Methyl-d-Aspartate Receptor Encephalitis

BACKGROUND

Anti-N-methyl-d-aspartate receptor encephalitis is a central nervous system inflammatory autoimmune disease affecting adults and children. The use of first- and second-line immunotherapies is supported. Recent reports suggest the efficacy of bortezomib in severe anti-N-methyl-d-aspartate encephalitis in adult patients not responsive to second-line treatment; there are no data about pediatric patients.

PATIENT DESCRIPTION

We describe an eight-year-old child with anti-N-methyl-d-aspartate encephalitis not responsive to first- and second-line treatments who experienced marked clinical improvement after bortezomib administration.

DISCUSSION

Bortezomib is a selective and reversible inhibitor of the 26S proteasome, which is used to treat oncologic and rare autoimmune disorders in pediatric patients. As observed in adult patients, bortezomib administration induced anti-N-methyl-d-aspartate antibody titer decline and clinical improvement with an acceptable risk profile.

CONCLUSION

This is the first report of the use of bortezomib in children with anti-N-methyl-d-aspartate encephalitis; it could be a useful therapeutic option in children with refractory anti-N-methyl-d-aspartate encephalitis.

Is There a Future for Anti-CD38 Antibody Therapy in Systemic Autoimmune Diseases?

CD38 is a type II glycoprotein highly expressed on plasmablasts, short-lived and long-lived plasma cells, but weakly expressed on other lymphoid cells, myeloid cells and non-hematopoietic cells. This expression pattern makes CD38 an interesting target for a targeted therapy aiming to deplete antibody-producing plasma cells. We present data suggesting that anti-CD38 therapy may be effective for the prevention at the preclinical stage and for the treatment of established autoimmune diseases, such as systemic lupus erythematosus, systemic sclerosis, Sjögren’s syndrome and anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis. Given the high unmet need for efficacious disease-modifying treatment in these diseases, studies are warranted to determine if anti-CD38 antibody-based therapies may delay or prevent the disease progression of systemic autoimmune diseases.

[Research progress on selective immunoproteasome inhibitors]

Immunoproteasome is associated with various diseases such as hematologic malignancies, inflammatory, autoimmune and central nervous system diseases, and over expression of immunoproteasome is observed in all of these diseases. Immunoproteasome inhibitors can reduce the expression of immunoproteasome by inhibiting the production of related cell-inducing factors and the activity of T lymphocyte for treating related diseases. In order to achieve good efficacy and reduce the toxic effects, key for development of selective immunoproteasome inhibitors is the high selectivity and potent activity of the three active subunits of the proteasome. This review summarizes the structure and functions of immunoproteasome and the associated diseases. Besides, structure, activity and status of selective immunoproteasome inhibitors are also been highlighted.

The impact of body composition parameters on severe toxicity of nivolumab

BACKGROUND

The occurrence of severe, acute limiting toxicity in patients receiving anti-programmed cell death receptor-1 monoclonal antibodies, such as nivolumab, is largely unpredictable. Sarcopenia was found to be associated with anti-cytotoxic T-lymphocyte-associated protein 4 acute toxicity. We explore the clinical and pharmacological parameters influencing nivolumab toxicity, including body composition.

METHODS

From June 2015 to January 2017, all consecutive patients treated with nivolumab in our institution were prospectively included. We studied the relationship between muscle mass assessed by computed tomography, nivolumab trough level (C_min) at day 14 assessed using the enzyme-linked immunosorbent assay method, and the occurrence of immune grade III or IV toxicity or any toxicity leading to treatment discontinuation (immune-related acute limiting toxicity [irALT]).

RESULTS

In our population (n = 92) with a majority of lung cancer (72%), forty-five (51.7%) patients were sarcopenic. The median plasma nivolumab C_min at day 14 was 15.4 μg/mL (interquartile range = 11.8-21.0). In multivariate analysis, hypoalbuminaemia (<35 g/L) was independently associated with low nivolumab C_min on day 14 (odds ratio [OR] = 0.09; 95% confidence interval [CI] = 0.01-0.59, p = 0.01) and overweight/obesity with high nivolumab C_min on day 14 (OR = 5.94; 95% CI = 1.25-28.29, p = 0.03). We observed 22 irALTs in 19 patients (21%). The most frequent irALT was respiratory (6.5%) disorders and gastrointestinal (4.3%) disorders. Patients with sarcopenia were at significantly increased risk of experiencing an irALT (OR = 3.84; 95% CI = 1.02-14.46, p = 0.047). No association was found between toxicity and nivolumab plasma C_min at day 14.

CONCLUSIONS

Our results highlight the importance of assessing body composition and suggest that sarcopenia could predict severe immune-related toxicity of nivolumab in real life.

B cell targeted therapies in autoimmune disease

PURPOSE OF REVIEW

FDA-approved B cell-targeted therapy has expanded to a multitude of autoimmune diseases ranging from organ specific diseases, like pemphigus and multiple sclerosis, to systemic diseases such as ANCA-associated vasculitis, rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). In this review, we discuss the variability in response to B cell-targeted therapies with a focus on the diversity of human B cells and plasma cells, and will discuss several of the promising new B cell-targeted therapies.

RECENT FINDING

The pathogenic roles for B cells include autoantibody-dependent and autoantibody-independent functions whose importance may vary across diseases or even in subsets of patients with the same disease. Recent data have further demonstrated the diversity of human B cell subsets that contribute to disease as well as novel pathways of B cell activation in autoimmune disease. The importance of eliminating autoreactive B cells and plasma cells will be discussed, as well as new approaches to do so.

SUMMARY

The past several years has witnessed significant advances in our knowledge of human B cell subsets and function. This has created a nuanced picture of the diverse ways B cells contribute to autoimmunity and an ever-expanding armamentarium of B cell-targeted therapies.

Chemical Patterns of Proteasome Inhibitors: Lessons Learned from Two Decades of Drug Design

Drug discovery now faces a new challenge, where the availability of experimental data is no longer the limiting step, and instead, making sense of the data has gained a new level of importance, propelled by the extensive incorporation of cheminformatics and bioinformatics methodologies into the drug discovery and development pipeline. These enable, for example, the inference of structure-activity relationships that can be useful in the discovery of new drug candidates. One of the therapeutic applications that could benefit from this type of data mining is proteasome inhibition, given that multiple compounds have been designed and tested for the last 20 years, and this collection of data is yet to be subjected to such type of assessment. This study presents a retrospective overview of two decades of proteasome inhibitors development (680 compounds), in order to gather what could be learned from them and apply this knowledge to any future drug discovery on this subject. Our analysis focused on how different chemical descriptors coupled with statistical tools can be used to extract interesting patterns of activity. Multiple instances of the structure-activity relationship were observed in this dataset, either for isolated molecular descriptors (e.g., molecular refractivity and topological polar surface area) as well as scaffold similarity or chemical space overlap. Building a decision tree allowed the identification of two meaningful decision rules that describe the chemical parameters associated with high activity. Additionally, a characterization of the prevalence of key functional groups gives insight into global patterns followed in drug discovery projects, and highlights some systematically underexplored parts of the chemical space. The various chemical patterns identified provided useful insight that can be applied in future drug discovery projects, and give an overview of what has been done so far.

General principles and escalation options of immunotherapy in autoantibody-associated disorders of the CNS

Autoimmune diseases associated with antineuronal and antiglial autoantibodies (Abs) is one of the most rapidly expanding research fields in clinical neuroimmunology, with more than 30 autoantibodies described so far. Being associated with a wide range of clinical presentations these syndromes can be diagnostically challenging. Surface or intracellular antigen localizations are crucial for the treatment response and outcome. In the latter Abs are mostly of paraneoplastic cause and tumor management should be performed as soon as possible in order to stop peripheral antigen stimulation. Immunotherapy should be started early in both groups, before irreversible neuronal loss occurs. Despite serious prognosis, aggressive therapeutic approaches can be effective in many cases. In this article we review main pathogenic mechanisms leading to Abs-related syndromes and describe standard as well as emerging strategies of immunotherapy, including tocilizumab and bortezomib. Several special therapeutic approaches will be illustrated by clinical cases recently treated in our department.

Immunoproteasome-selective inhibitors: An overview of recent developments as potential drugs for hematologic malignancies and autoimmune diseases

The immunoproteasome, a specialized form of proteasome, is mainly expressed in lymphocytes and monocytes of jawed vertebrates and responsible for the generation of antigenic peptides for cell-mediated immunity. Overexpression of immunoproteasome have been detected in a wide range of diseases including malignancies, autoimmune and inflammatory diseases. Following the successful approval of constitutive proteasome inhibitors bortezomib, carfilzomib and Ixazomib, and with the clarification of immunoproteasome crystal structure and functions, a variety of immunoproteasome inhibitors were discovered or rationally developed. Not only the inhibitory activities, the selectivities for immunoproteasome over constitutive proteasome are essential for the clinical potential of these analogues, which has been validated by the clinical evaluation of immunoproteasome-selective inhibitor KZR-616 for the treatment of systemic lupus erythematosus. In this review, structure, function as well as the current developments of various inhibitors against immunoproteasome are going to be summarized, which help to fully understand the target for drug discovery.

[New directions of pharmacotherapy of immune - inflammatory rheumatic diseases]

Deciphering immunopathogenesis, expanding the scope of diagnostics and developing new methods for treating human autoimmune diseases are among the priority areas of XXI century medicine. Particularly widely autoimmune pathology is presented in immunoinflammatory rheumatic diseases (IIRD), such as rheumatoid arthritis, systemic lupus erythematosus, systemic scleroderma, systemic vasculitis associated with the synthesis of antineutrophilic cytoplasmic antibodies, Sjogren's syndrome, idiopathic inflammatory myopathies and other other types of others. Deciphering the pathogenesis mechanisms of IIRD created the prerequisites for improving pharmacotherapy, which in the future should lead to a dramatic improvement in the prognosis for these diseases. The review discusses new approaches to IIRD pharmacotherapy associated with the inhibition of tumor necrosis factor-α, interleukin-6 (IL-6), IL-1β, IL-17, IL-23, and the prospects for using Janus kinase inhibitors, depending on the prevailing pathogenesis mechanisms - autoimmunity or autoinflammation.

Shared and Unique Patterns of DNA Methylation in Systemic Lupus Erythematosus and Primary Sjögren's Syndrome

Objectives: To perform a cross-comparative analysis of DNA methylation in patients with systemic lupus erythematosus (SLE), patients with primary Sjögren's syndrome (pSS), and healthy controls addressing the question of epigenetic sharing and aiming to detect disease-specific alterations.

Methods: DNA extracted from peripheral blood from 347 cases with SLE, 100 cases with pSS, and 400 healthy controls were analyzed on the Human Methylation 450k array, targeting 485,000 CpG sites across the genome. A linear regression model including age, sex, and blood cell type distribution as covariates was fitted, and association p-values were Bonferroni corrected. A random forest machine learning classifier was designed for prediction of disease status based on DNA methylation data.

Results: We established a combined set of 4,945 shared differentially methylated CpG sites (DMCs) in SLE and pSS compared to controls. In pSS, hypomethylation at type I interferon induced genes was mainly driven by patients who were positive for Ro/SSA and/or La/SSB autoantibodies. Analysis of differential methylation between SLE and pSS identified 2,244 DMCs with a majority of sites showing decreased methylation in SLE compared to pSS. The random forest classifier demonstrated good performance in discerning between disease status with an area under the curve (AUC) between 0.83 and 0.96.

Conclusions: The majority of differential DNA methylation is shared between SLE and pSS, however, important quantitative differences exist. Our data highlight neutrophil dysregulation as a shared mechanism, emphasizing the role of neutrophils in the pathogenesis of systemic autoimmune diseases. The current study provides evidence for genes and molecular pathways driving common and disease-specific pathogenic mechanisms.

Small-Molecule Inhibitors of the Proteasome's Regulatory Particle

Cells need to synthesize and degrade proteins consistently. Maintaining a balanced level of protein in the cell requires a carefully controlled system and significant energy. Degradation of unwanted or damaged proteins into smaller peptide units can be accomplished by the proteasome. The proteasome is composed of two main subunits. The first is the core particle (20S CP), and within this core particle are three types of threonine proteases. The second is the regulatory complex (19S RP), which has a myriad of activities including recognizing proteins marked for degradation and shuttling the protein into the 20S CP to be degraded. Small-molecule inhibitors of the 20S CP have been developed and are exceptional treatments for multiple myeloma (MM). 20S CP inhibitors disrupt the protein balance, leading to cellular stress and eventually to cell death. Unfortunately, the 20S CP inhibitors currently available have dose-limiting off-target effects and resistance can be acquired rapidly. Herein, we discuss small molecules that have been discovered to interact with the 19S RP subunit or with a protein closely associated with 19S RP activity. These molecules still elicit their toxicity by preventing the proteasome from degrading proteins, but do so through different mechanisms of action.

Cellular Responses to Proteasome Inhibition: Molecular Mechanisms and Beyond

Proteasome inhibitors have been actively tested as potential anticancer drugs and in the treatment of inflammatory and autoimmune diseases. Unfortunately, cells adapt to survive in the presence of proteasome inhibitors activating a variety of cell responses that explain why these therapies have not fulfilled their expected results. In addition, all proteasome inhibitors tested and approved by the FDA have caused a variety of side effects in humans. Here, we describe the different types of proteasome complexes found within cells and the variety of regulators proteins that can modulate their activities, including those that are upregulated in the context of inflammatory processes. We also summarize the adaptive cellular responses activated during proteasome inhibition with special emphasis on the activation of the Autophagic-Lysosomal Pathway (ALP), proteaphagy, p62/SQSTM1 enriched-inclusion bodies, and proteasome biogenesis dependent on Nrf1 and Nrf2 transcription factors. Moreover, we discuss the role of IRE1 and PERK sensors in ALP activation during ER stress and the involvement of two deubiquitinases, Rpn11 and USP14, in these processes. Finally, we discuss the aspects that should be currently considered in the development of novel strategies that use proteasome activity as a therapeutic target for the treatment of human diseases.