Generation and characterization of antagonistic anti-human interleukin (IL)-18 monoclonal antibodies with high affinity: Two types of monoclonal antibodies against full-length IL-18 and the neoepitope of inflammatory caspase-cleaved active IL-18

Monoclonal Antibodies Against Mature Interleukin-18 Ameliorate Colitis and Repair Goblet Cell Function

BACKGROUND

Numerous biological interventions and small molecules are used to treat Crohn's disease; however, the effectiveness of these treatments varies largely. Non-responsiveness to biological therapies is associated with interleukin (IL)-18 gene polymorphisms and high IL-18 expression has been implicated in the pathogenesis of Crohn's disease.

AIMS

The aim of this study was to elucidate the expression of precursor and mature IL-18 in patients with Crohn's disease who exhibited varied responses to cytokine-targeted treatments and determine whether selective inhibition of mature IL-18 offers a novel therapeutic avenue.

METHODS

We generated a monoclonal antibody that specifically recognizes the neoepitope of caspase-cleaved mature IL-18. Expression of precursor and mature IL-18 was analyzed in patients with Crohn's disease. Anti-mature IL-18 monoclonal antibodies were intraperitoneally administered in an acute colitis mouse model, and the disease activity index, body weight loss, tissue pathology, proinflammatory cytokine expression, goblet cell function, and microbiota composition were assessed.

RESULTS

Precursor and mature IL-18 expression was upregulated and goblet cell function was impaired in patients with Crohn's disease who were unresponsive to biological therapies. Administration of anti-mature IL-18 antibodies ameliorated induced colitis by repairing goblet cell function and restoring the mucus layer.

CONCLUSIONS

The newly developed monoclonal antibody holds promise as a therapeutic alternative for Crohn's disease.

Monoclonal Antibody Against Mature Interleukin-18 Ameliorates Colitis in Mice and Improves Epithelial Barrier Function

BACKGROUND

Antitumor necrosis factor (TNF)-α antibodies have improved the outcome of inflammatory bowel disease (IBD); but half of patients remain unresponsive to treatment. Interleukin-18 (IL-18) gene polymorphism is associated with resistance to anti-TNF-α antibodies, but therapies targeting IL-18 have not been clinically applied. Only the mature protein is biologically active, and we aimed to investigate whether specific inhibition of mature IL-18 using a monoclonal antibody (mAb) against a neoepitope of caspase-cleaved mature IL-18 could be an innovative treatment for IBD.

METHODS

The expression of precursor and mature IL-18 in patients with UC was examined. Colitis was induced in C57/BL6 mice by administering dextran sulfate sodium (DSS), followed by injection with anti-IL-18 neoepitope mAb. Colon tissues were collected and subjected to histological analysis, immunohistochemistry, immunoblotting, and quantitative polymerase chain reaction. Colon epithelial permeability and microbiota composition were analyzed.

RESULTS

Mature IL-18 expression was elevated in colon tissues of patients with active ulcerative colitis. Administration of anti-IL-18 neoepitope mAb ameliorated acute and chronic DSS-induced colitis; reduced interferon-γ, TNF-α, and chemokine (CXC motif) ligand-2 production and epithelial cell permeability; promoted goblet cell function; and altered the intestinal microbiome composition. The suppressive effect of anti-IL-18 neoepitope mAb was superior to that of anti-whole IL-18 mAb. Furthermore, combination therapy with anti-TNF-α Ab suppressed acute and chronic colitis additively by suppressing cytokine expressions and reducing cell permeability by upregulating claudin1 and occludin expression.

CONCLUSIONS

Anti-IL-18 neoepitope mAb ameliorates acute and chronic colitis, suggesting that this mAb will be an innovative therapeutic option for IBD.

Establishment of Sensitive Sandwich-Type Chemiluminescence Immunoassay for Interleukin-18 in Urinary Samples

Interleukin-18 (IL-18), a member of IL-1 cytokine superfamily, is deemed as an important indicator of the kidney disease. Herein a sandwich chemiluminescence immunoassay integrated with magnetic beads was conducted to detect IL-18 in kidney disease. The detection limit and linear range were 0.0044 ng/mL and 0.01-2.7 ng/mL, respectively. Satisfactory recoveries were ranged from 91.70 to 101.18% with the relative standard deviation below 10%; interference bias of most biomarkers were within allowable deviation range (± 15%). In summary, the whole study was successfully applied to detect IL-18 levels in urine samples for patients with kidney disease. The results showed that chemiluminescence immunoassay for IL-18 detection could be used in the clinical application.

Generation of the novel anti-FXYD5 monoclonal antibody and its application to the diagnosis of pancreatic and lung cancer

Despite recent advances in cancer treatments, pancreatic cancer has a dismal prognosis globally. Early detection of cancer cells and effective treatments for recalcitrant tumors are required, but the innovative therapeutic tools remain in development. Cancer-specific antigens expressed only on cancer cells may help resolve these problems, and antibodies to such antigens have potential in basic research and clinical applications. To generate specific antibodies that bind to proteins expressed on the surface of pancreatic cancer cells, we immunized mice with human pancreatic cancer MIA PaCa-2 cells, and isolated a hybridoma that produces a monoclonal antibody (mAb), named 12-13.8. This antibody was applied to molecular biological experiments such as immunocytochemistry, immunoblotting, flow cytometry, and immunoprecipitation. In addition, we showed that mAb 12-13.8 could accumulate in tumors, through in vivo experiments using cancer-bearing mice. Immunohistochemical staining of pancreatic and lung tumor tissues indicated that the increase of the staining strength by mAb 12-13.8 positively and inversely correlated with the patients' cancer recurrence and survival rate, respectively. We identified the FXYD5 protein as the target protein of mAb 12-13.8, by a human protein array screening system. The FXYD5 protein is overexpressed in various types of cancer and is modified by O-linked glycosylation. We confirmed the binding of the FXYD5 protein to mAb 12-13.8 by using FXYD5-knockout MIA PaCa-2 cells, and detailed epitope mapping identified amino acid residues 45-52 as the minimal peptide sequence. Our results indicate that mAb 12-13.8 could be a valuable tool for FXYD5 studies, and useful in diagnostic and drug delivery applications for cancer patients.

The Expanding Spectrum of Autoinflammatory Diseases

Autoinflammatory diseases are systemic disorders caused by genetic or acquired abnormalities in certain signaling pathways of the innate immune system. Dysregulated activation of the inflammasome, i.e. molecular platforms responsible for the activation of caspase-1 and production of interleukin-1β, causes autoinflammation. Familial Mediterranean fever (FMF), the most common genetic autoinflammatory disease, is characterized by a periodic fever and serositis. The complex and heterogeneous genetic background of Japanese FMF patients, accompanied by potential overlap with other rheumatic diseases, suggests crosstalk between genetic and environmental factors. Recently, FMF has been recognized as being part of a spectrum of autoinflammatory syndromes named pyrin-associated autoinflammatory diseases. The discovery of a new monogenic autoinflammatory disease, A20 haploinsufficiency, may provide novel insights into early-onset Behçet's-like diseases. In contrast, adult-onset Still's disease and Schnitzler's syndrome are acquired autoinflammatory diseases without a monogenic abnormality. Although the concept of autoinflammatory diseases originally applied to monogenic hereditary recurrent fevers, it has been expanded to include non-genetic complex autoinflammatory diseases. Information concerning monogenic autoinflammatory diseases may prove useful for elucidating the molecular mechanisms underlying non-genetic autoinflammatory diseases.

Autoinflammatory disease: clinical perspectives and therapeutic strategies

The molecular platforms of the innate immune system are essential to recognize pathologic external factors that are crucial to differentiate these danger signals from host motifs. A set of sensors recognizing pathologic factors is present and defined as a membrane-bound family of Toll-like receptors as well as the cytosolic ones including the family of nucleotide-binding domain leucine-rich repeat proteins. In this regard, the inflammasomes have been identified as an innate immune sensor toward pathologic external factors as well as endogenous damage-associated molecular pattern signals transducing from the above-mentioned receptors to gene expressions. Recent research has shown novel findings in inflammasome biology and genetics which lead to the alteration of diagnosis and management in autoinflammatory diseases as well as developing novel treatments, including the examples of nucleotide-binding domain leucine-rich repeat proteins-inflammasomes and pyrin-inflammasomes. The pyrin protein is encoded by the Mediterranean Fever gene on chromosome 16 that acts as a major regulatory component of the inflammasome, and is responsible for familial Mediterranean fever. We have recently examined the whole nucleotide sequence of the Mediterranean Fever gene in Japanese familial Mediterranean fever patients and revealed single nucleotide variants associated with the susceptibility of familial Mediterranean fever from a nation-wide survey by the next-generation sequencing. In a cytokine profile analysis of familial Mediterranean fever patients, we have found that interleukin-6 is considered to be one of the most crucial cytokines in familial Mediterranean fever attack since interleukin-6 had the best performance for distinguishing familial Mediterranean fever in attack from healthy controls or familial Mediterranean fever in remission, and in vitro interleukin-6 production is regulated by microRNAs-204-3p/phosphoinositide 3-kinase g pathway. Accordingly, we have been investigating the efficacy and safety of anti-human interleukin-6 receptor monoclonal antibody, tocilizumab, in patients with familial Mediterranean fever refractory or intolerant to colchicine through an investigator-initiated clinical trial supported by the Japan Agency for Medical Research and Development. Like interleukin-1b, interleukin-18 can be processed by caspase-1 and proteinase-3 to be activated within the inflammasomes. We have also found the importance of interleukin-18 in several autoinflammatory conditions. Recently, the concept of autoinflammation is widely distributed into many common diseases; thus, the attention to a wide spectrum of diseases MEFV gene deeply involved is required.

Interleukin-18 cytokine in immunity, inflammation, and autoimmunity: Biological role in induction, regulation, and treatment

Interleukin-18 (IL-18) is a potent pro-inflammatory cytokine involved in host defense against infections and regulates the innate and acquired immune response. IL-18 is produced by both hematopoietic and non-hematopoietic cells, including monocytes, macrophages, keratinocytes and mesenchymal cell. IL-18 could potentially induce inflammatory and cytotoxic immune cell activities leading to autoimmunity. Its elevated levels have been reported in the blood of patients with some immune-related diseases, including rheumatoid arthritis, systemic lupus erythematosus, type I diabetes mellitus, atopic dermatitis, psoriasis, and inflammatory bowel disease. In the present review, we aimed to summarize the biological properties of IL-18 and its pathological role in different autoimmune diseases. We also reported some monoclonal antibodies and drugs targeting IL-18. Most of these monoclonal antibodies and drugs have only produced partial effectiveness or complete ineffectiveness in vitro, in vivo and human studies. The ineffectiveness of these drugs targeting IL-18 may be largely due to the loophole caused by the involvement of other cytokines and proteins in the signaling pathway of many inflammatory diseases besides the involvement of IL-18. Combination drug therapies, that focus on IL-18 inhibition, in addition to other cytokines, are highly recommended to be considered as an important area of research that needs to be explored.

Interleukin-18: a biomarker with therapeutic potential in adult-onset Still's disease

INTRODUCTION

Adult-onset Still's disease (AOSD) is an autoinflammatory disease driven by the innate immune response. Given the ambiguity in clinical presentation and lack of specific diagnostic biomarkers, AOSD diagnosis is usually delayed in the early stage. Because AOSD is a rare disease with clinical heterogeneity, there is no consensus on its treatment currently. This review summarizes the current research evidence regarding the pathogenic role and the diagnostic or therapeutic potential of interleukin (IL)-18 in AOSD.

AREAS COVERED

We searched the MEDLINE database using the PubMed interface and reviewed English-language literature from 1971 to 2022. This review focusing on IL-18 discusses its pathogenic role and clinical implications in AOSD.

EXPERT OPINION

NLRP3-inflammasome activation with IL-18 overproduction plays a pathogenic role in AOSD. IL-18 is closely linked to the clinical manifestations and disease activity of AOSD and may be a diagnostic biomarker. Given its pathogenic role in AOSD, IL-18 could become a potential therapeutic target. IL-18 binding protein (IL-18BP) negatively regulates the biological activity of IL-18 by inhibiting IL-18 signaling, and a clinical trial revealed that IL-18BP (Tadekinig alfa) treatment was well-tolerated and effective for AOSD. Recently, monoclonal antibodies against IL-18 have been under evaluation in a phase 1b trial.

Generation of antagonistic monoclonal antibodies against the neoepitope of active mouse interleukin (IL)-18 cleaved by inflammatory caspases

Interleukin 18 (IL-18) is a member of the IL-1 family and plays an important role in both the innate and acquired immune systems. It is constitutively expressed as an inactive precursor (24 kDa) in various cell types, and the mature IL-18 (18 kDa) cleaved by inflammatory caspase-1/4 binds to the interleukin-18 receptor, thereby activating downstream signaling pathways. We previously generated anti-human IL-18 antibodies that specifically recognize the human IL-18 neoepitope cleaved by inflammatory caspase-1/4. Because the N-terminal amino acid sequences of the neoepitopes are different between human IL-18 and mouse IL-18, the anti-human IL-18 neoepitope antibodies do not recognize mouse mature IL-18. We have now generated novel anti-mouse IL-18 neoepitope antibodies. We also confirmed CXCL2 secretion from P-815 mouse cells by mouse IL-18 stimulation, and established a simple assay to evaluate the activity of mouse IL-18. Using this evaluation system, we confirmed that the anti-mouse IL-18 neoepitope antibodies could inhibit mouse IL-18. By demonstrating the therapeutic efficacy of the anti-mouse IL-18 neoepitope and function-blocking mAbs established in the present study in mouse models, corresponding to human inflammatory diseases in which IL-18 may be involved, such as inflammatory bowel diseases, we can provide the proof-of-concept that the previously established anti-human IL-18 neoepitope and function-blocking mAbs work in human inflammatory disorders corresponding to mouse models.

The Expanding Spectrum of Autoinflammatory Diseases

Autoinflammatory diseases are systemic disorders caused by genetic or acquired abnormalities in certain signaling pathways of the innate immune system. Dysregulated activation of the inflammasome, i.e. molecular platforms responsible for the activation of caspase-1 and production of interleukin-1β, causes autoinflammation. Familial Mediterranean fever (FMF), the most common genetic autoinflammatory disease, is characterized by a periodic fever and serositis. The complex and heterogeneous genetic background of Japanese FMF patients, accompanied by potential overlap with other rheumatic diseases, suggests crosstalk between genetic and environmental factors. Recently, FMF has been recognized as being part of a spectrum of autoinflammatory syndromes named pyrin-associated autoinflammatory diseases. The discovery of a new monogenic autoinflammatory disease, A20 haploinsufficiency, may provide novel insights into early-onset Behçet's-like diseases. In contrast, adult-onset Still's disease and Schnitzler's syndrome are acquired autoinflammatory diseases without a monogenic abnormality. Although the concept of autoinflammatory diseases originally applied to monogenic hereditary recurrent fevers, it has been expanded to include non-genetic complex autoinflammatory diseases. Information concerning monogenic autoinflammatory diseases may prove useful for elucidating the molecular mechanisms underlying non-genetic autoinflammatory diseases.

Hypoxia‐inducible factor (HIF)‐1α‐induced regulation of lung injury in pulmonary aspiration is mediated through NF‐kB

Aspiration‐induced lung injury is a common grievance encountered in the intensive care unit (ICU). It is a significant risk factor for improving ventilator‐associated pneumonia (VAP) and acute respiratory distress syndrome (ARDS). Hypoxia‐inducible factor (HIF)‐1α is one of the primary transcription factors responsible for regulating the cellular response to changes in oxygen tension. Here, we sought to determine the role of HIF‐1α and specifically the role of type 2 alveolar epithelial cells in generating the acute inflammatory response following acid and particles (CASP) aspiration. Previous studies show HIF‐1 α is involved in regulating the hypoxia‐stimulated expression of MCP‐1 in mice and humans. The CASP was induced in C57BL/6, ODD‐Luc, HIF‐1α (+/+) control, and HIF‐1α conditional knockout (HIF‐1α (−/−) mice). Following an injury in ODD mice, explanted organs were subjected to IVIS imaging to measure the degree of hypoxia. HIF‐1α expression, BAL albumin, cytokines, and histology were measured following CASP. In C57BL/6 mice, the level of HIF‐1α was increased at 1 h after CASP. There were significantly increased levels of albumin and cytokines in C57BL/6 and ODD‐Luc mice lungs following CASP. HIF‐1α (+/+) mice given CASP demonstrated a synergistic increase in albumin leakage, increased pro‐inflammatory cytokines, and worse injury. MCP‐1 antibody neutralized HIF‐1α (+/+) mice showed reduced granuloma formation. The NF‐κB expression was increased substantially in the HIF‐1α (+/+) mice following CASP compared to HIF‐1α (−/−) mice. Our data collectively identify that HIF‐1α upregulation of the acute inflammatory response depends on NF‐κB following CASP.

Exploring Molecular Mechanisms Involved in the Development of the Depression-Like Phenotype in Interleukin-18-Deficient Mice

Interleukin-18 (IL-18) is an inflammatory cytokine that has been linked to energy homeostasis and psychiatric symptoms such as depression and cognitive impairment. We previously revealed that deficiency in IL-18 led to hippocampal abnormalities and resulted in depression-like symptoms. However, the impact of IL-18 deficiency on other brain regions remains to be clarified. In this study, we first sought to confirm that IL-18 expression in neural cells can be found in human brain tissue. Subsequently, we examined the expression of genes in the prefrontal cortex of Il18^−/− mice and compared it with gene expression in mice subjected to a chronic mild stress model of depression. Extracted genes were further analyzed using Ingenuity® Pathway Analysis, in which 18 genes common to both the chronic mild stressed model and Il18^−/− mice were identified. Of those, 16 were significantly differentially expressed between Il18^+/+ and Il18^−/− mice. We additionally measured protein expression of α-2-HS-glycoprotein (AHSG) and transthyretin (TTR) in serum and the brain. In the prefrontal cortex of Il18^−/− mice, TTR but not AHSG was significantly decreased. Conversely, in the serum of Il18^−/− mice, AHSG was significantly increased but not TTR. Therefore, our results suggest that in IL-18-deficit conditions, TTR in the brain is one of the mediators causally related to depression, and AHSG in peripheral organs is one of the regulators inducing energy imbalance. Moreover, this study suggests a possible “signpost” to clarify the molecular mechanisms commonly underlying the immune system, energy metabolism, neural function, and depressive disorders.

Bioanalytical Challenges in Support of Complex Modalities of Antibody-Based Therapeutics

Antibody-based therapeutic classes are evolving from monoclonal antibodies to antibody derivatives with complex structures to achieve advanced therapeutic effect. These antibody derivatives may contain multiple functional domains and are often vulnerable to in vivo biotransformation. Understanding the pharmacokinetics of these antibody derivatives requires a sophisticated bioanalytical approach to carefully characterize the whole drug and each functional domain with respect to quantity, functionality enabled by biotransformation, and corresponding immune responses. Ligand binding assays and liquid chromatography-mass spectrometry assays are predominantly used in bioanalytical support of monoclonal antibodies and are continuously used for antibody derivatives such as antibody drug conjugate and bispecific antibodies. However, they become increasingly cumbersome in coping with increased complexity of drug modality and associated biotransformation. In this mini-review, we examined the current pharmacokinetic assays in the literature for antibody drug conjugate and bispecific antibodies, and presented our view of promising bioanalytical technologies to address the distinct bioanalytical needs of complex modalities.

Clinical characteristics and comorbidities in adult-onset Still's disease using a large US administrative claims database

OBJECTIVES

We aimed to describe clinical characteristics, treatment patterns and major comorbidities of a US-based adult-onset Still's disease (AOSD) cohort.

METHODS

Administrative claims data from Truven MarketScan were collected from 2009 to 2015. An AOSD case was defined as ≥1 M06.1 International Classification of Diseases 10th revision (ICD-10) medical claim code. We extracted data for the AOSD cohort (n = 106) and 1:5 matched controls (n = 530) without AOSD. Outcomes of interest and a novel claims-based set of Yamaguchi criteria were identified by relevant ICD 9th revision (ICD-9) and ICD-10 codes. Bivariate descriptive analyses were conducted on all variables. Comorbidity rates and rate ratios were calculated in AOSD cases and matched controls. Statistical significance of cohort differences was determined to compare AOSD cases and matched controls.

RESULTS

The AOSD cohort, with a mean age of 43.08 (standard deviation, s.d. 13.9) years and with female predominance (68.9%) was observed over a mean of 750.12 (637.6) days. A total of 35.9% of AOSD patients fulfilled claims-based Yamaguchi criteria compared with 0.4% matched controls (P< 0.05). We identified severe AOSD-related complications, including macrophage activation syndrome (4.7%) and acute respiratory distress syndrome (12.3%). Treatment commonly involved systemic glucocorticoids (62.2%), MTX (51%) and anakinra (24.5%). Compared with matched controls, serious infections were significantly increased (rate ratio 2.58, 95% CI: 1.53, 4.37, P = 0.0004), while hyperlipidaemia (0.54, 95% CI: 0.35, 0.85; P = 0.008) and obesity (0.30, 95% CI: 0.15, 0.62; P = 0.001) were significantly decreased in AOSD patients.

CONCLUSION

We characterized a first US-based AOSD cohort using a large national administrative claims database, and identified key complications, treatments and comorbidities.

Human Autoinflammatory Diseases Mediated by NLRP3-, Pyrin-, NLRP1-, and NLRC4-Inflammasome Dysregulation Updates on Diagnosis, Treatment, and the Respective Roles of IL-1 and IL-18

Recent research has led to novel findings in inflammasome biology and genetics that altered the diagnosis and management of patients with autoinflammatory syndromes caused by NLRP3-, Pyrin-, NLRP1-, and NLRC4-inflammasomes and spurred the development of novel treatments. The use of next-generation sequencing in clinical practice allows for rapid diagnosis and the detection of somatic mutations that cause autoinflammatory diseases. Clinical differences in patients with NLRP3, pyrin, and NLRP1 inflammasomopathies, and the constitutive elevation of unbound free serum IL-18 that predisposes to the development of macrophage activation syndrome (MAS) in patients with gain-of function mutations in NLRC4 led to the screening and the characterization of novel diseases presenting with constitutively elevated serum IL-18 levels, and start to unravel the biology of "high IL-18 states" that translate into the use of biomarkers that improve diagnosis and monitoring of disease activity and investigations of treatments that target IL-18 and IFN-gamma which promise to improve the management and outcome of these conditions. Lastly, advances in structural modeling by cryo-electron microscopy (cryo-EM) of gasdermin, and of NLRP3- and NLRC4-inflammasome assembly, and the characterization of post-translational modifications (PTM) that regulate inflammasome activation, coupled with high-throughput screening (HTS) of libraries of inflammasome-inhibiting compounds, promise a new generation of treatments for patients with inflammasome-mediated diseases.

Beneficial Effects of Sagacious Confucius' Pillow Elixir on Cognitive Function in Senescence-Accelerated P8 Mice (SAMP8) via the NLRP3/Caspase-1 Pathway

Sagacious Confucius' Pillow Elixir (SCPE) is a traditional Chinese medicine that is mainly used for cognitive impairment in aging; however, the underlying mechanisms remain unclear. Aging is one of the most important pathogenic factors leading to inflammation and pyroptosis in the hippocampus, which may be a potential mechanism in elderly patients with cognitive impairment. Here, we examined whether SCPE could improve cognitive impairment in SAMP8 mice by reducing hippocampal inflammation and pyroptosis. Seven-month-old senescence-accelerated P8 mice (SAMP8) received SCPE (2.3 g/kg/day; 4.6 g/kg/day; 9.2 g/kg/day) for 28 days. Cognitive function and morphometric examinations were performed followed by water maze testing, hematoxylin-eosin staining, Congo red staining, toluidine blue staining, and TUNEL analysis of hippocampal CA1 and CA3 regions. Escape latency increased and times across platforms decreased in SAMP8 mice; however, both of them were normalized by SCPE after 28 days. Aging caused significant pyroptosis in hippocampal CA1 and CA3 regions, as evidenced by neuronal degeneration and necrosis, amyloid deposition, and decreased Nissl body amounts after cognitive impairment, which were greatly improved by SCPE. SCPE reduced serum IL-1β, IL-6, IL-18, and TNF-α levels and reduced hippocampal NLRP3, ASC, caspase-1, GSDM-D, IL-1β, IL-6, IL-18, and Aβ expression. Thus, SCPE exerts an antipyroptotic effect in aging, mainly by suppressing the NLRP3/caspase-1 signaling pathway.