Structural Activation of Pro-inflammatory Human Cytokine IL-23 by Cognate IL-23 Receptor Enables Recruitment of the Shared Receptor IL-12Rβ1

Are single nucleotide polymorphisms underutilized for guiding treatment of inflammatory bowel disease?

Inflammatory bowel disease (IBD), encompassing Crohn's disease (CD), ulcerative colitis (UC) and IBD unclassified (IBDU), significantly impacts quality of life. Despite significant advances in the management of the conditions, responses to treatments vary greatly, and this is due partly to our natural genetic variation. Here we will review the evidence for whether single nucleotide polymorphisms (SNPs) have the potential to guide treatment decisions for people with IBD. We will first consider SNPs that exhibit strong associations with IBD pathogenesis and their relevance to epithelial barrier integrity, cytokine production, and immune system function. Then, we will cover those SNPs implicated in altering response to our various current IBD therapeutics, including the recently implemented drugs ustekinumab and tofacitinib. Finally, we will explore lesser-known SNPs that exhibit complex relationships with the disease and which may be undervalued as pharmacogenetic tools. Overall, it will be demonstrated that SNPs associated with IBD pathology are largely distinct from those predicting response to treatments and that new discoveries of clinically useful tools can be expected from therapy-focused investigations. Given the growing list of treatments available, we argue that beneficial personalization of treatments based on SNPs is still underutilized.

The Role of IL-23 in the Development of Inflammatory Diseases

Interleukin-23 is crucial in the initiation and progression of certain inflammatory disorders. As a key cytokine, IL-23 is involved in the differentiation and activation of Th17 cells, which play a role in a broad spectrum of inflammatory diseases. This review examines the molecular mechanisms through which IL-23 contributes to the pathogenesis of conditions including psoriasis, rheumatoid arthritis, inflammatory bowel disease, and multiple sclerosis. By elucidating the significant role of IL-23 in inflammation, this review underscores its importance as a therapeutic target for managing inflammatory conditions, with particular emphasis on current and emerging biologic treatments.

Guselkumab binding to CD64+ IL-23-producing myeloid cells enhances potency for neutralizing IL-23 signaling

IL-23 is implicated in the pathogenesis of immune-mediated inflammatory diseases, and myeloid cells that express Fc gamma receptor 1 (FcγRI or CD64) on their surface have been recently identified as a primary source of IL-23 in inflamed tissue. Our complementary analyses of transcriptomic datasets from psoriasis and IBD showed increased expression of CD64 and IL-23 transcripts in inflamed tissue, and greater abundance of cell types with co-expression of CD64 and IL-23. These findings led us to explore potential implications of CD64 binding on the function of IL-23-targeting monoclonal antibodies (mAbs). Guselkumab and risankizumab are mAbs that target the IL-23p19 subunit. Guselkumab has a native Fc domain while risankizumab contains mutations that diminish binding to FcγRs. In flow cytometry assays, guselkumab, but not risankizumab, showed Fc-mediated binding to CD64 on IFNγ-primed monocytes. Guselkumab bound CD64 on IL-23-producing inflammatory monocytes and simultaneously captured IL-23 secreted from these cells. Guselkumab binding to CD64 did not induce cytokine production. In live-cell confocal imaging of CD64+ macrophages, guselkumab, but not risankizumab, mediated IL-23 internalization to low-pH intracellular compartments. Guselkumab and risankizumab demonstrated similar potency for inhibition of IL-23 signaling in cellular assays with exogenous addition of IL-23. However, in a co-culture of IL-23-producing CD64+ THP-1 cells with an IL-23-responsive reporter cell line, guselkumab demonstrated Fc-dependent enhanced potency compared to risankizumab for inhibiting IL-23 signaling. These in vitro data highlight the potential for guselkumab binding to CD64 in inflamed tissue to contribute to the potent neutralization of IL-23 at its cellular source.

The IL-23R and Its Genetic Variants: A Hitherto Unforeseen Bridge Between the Immune System and Cancer Development

IL-23R (interleukin-23 receptor), found on the surface of several immune cells, plays a key role in the immune system. Indeed, this process is not limited to the inflammatory response but also plays a role in the adaptive immune response. The binding between IL-23R and its specific ligand, the interleukin 23, initiates a number of specific signals by modulating both properties and behavior of immune cells. In particular, it is critical for the regulation of T helper 17 cells (Th17). Th17s are a subset of T cells involved in autoimmune and inflammatory diseases, as well as in cancer. The clinical relevance of IL-23R is underscored by its association with an elevated susceptibility or diminished vulnerability to a spectrum of diseases, including psoriasis, ankylosing spondylitis, and inflammatory bowel disease (IBD). Evidence has emerged that suggests it may also serve to predict both tumor progression and therapeutic responsiveness. It is noteworthy that the IL-23/IL-23R pathway is emerging as a promising therapeutic target. A number of biologic drugs, such as monoclonal antibodies, are currently developing with the aim of blocking this interaction, thus reducing inflammation. This represents a significant advancement in the field of medicine, offering new hope for pursuing more effective and personalized treatments. Recent studies have also investigated the role of such a pathway in autoimmune diseases, and its potential impact on infections as well as in carcinogenesis. The aim of this review is to focus on the role of IL-23R in immune genetics and its potential for modulating the natural history of neoplastic disease.

Kinetic analysis of fluorescent ligand binding to cell surface receptors: Insights into conformational changes and allosterism in living cells

Equilibrium binding assays are one of the mainstays of current drug discovery efforts to evaluate the interaction of drugs with receptors in membranes and intact cells. However, in recent years, there has been increased focus on the kinetics of the drug-receptor interaction to gain insight into the lifetime of drug-receptor complexes and the rate of association of a ligand with its receptor. Furthermore, drugs that act on topically distinct sites (allosteric) from those occupied by the endogenous ligand (orthosteric site) can induce conformational changes in the orthosteric binding site leading to changes in the association and/or dissociation rate constants of orthosteric ligands. Conformational changes in the orthosteric ligand binding site can also be induced through interaction with neighbouring accessory proteins and receptor homodimerisation and heterodimerisation. In this review, we provide an overview of the use of fluorescent ligand technologies to interrogate ligand-receptor kinetics in living cells and the novel insights that they can provide into the conformational changes induced by drugs acting on a variety of cell surface receptors including G protein-coupled receptors (GPCRs), receptor tyrosine kinases (RTKs) and cytokine receptors.

Structure and assembly of the human IL-12 signaling complex

Interleukin (IL)-12 is a heterodimeric pro-inflammatory cytokine. Our cryoelectron microscopy structure determination of human IL-12 in complex with IL-12Rβ1 and IL-12Rβ2 at a resolution of 3.75 Å reveals that IL-12Rβ2 primarily interacts with the IL-12p35 subunit via its N-terminal Ig-like domain, while IL-12Rβ1 binds to the p40 subunit with its N-terminal fibronectin III domain. This binding mode of IL-12 with its receptors is similar to that of IL-23 but shows notable differences with other cytokines. Through structural information and biochemical assays, we identified Y62, Y189, and K192 as key residues in IL-12p35, which bind to IL-12Rβ2 with high affinity and mediate IL-12 signal transduction. Furthermore, structural comparisons reveal two distinctive conformational states and structural plasticity of the heterodimeric interface in IL-12. As a result, our study advances our understanding of IL-12 signal initiation and opens up new opportunities for the engineering and therapeutic targeting of IL-12.

Effect of Whole-Body Electrical Muscle Stimulation Training on Inflammatory and Anti-inflammatory Cytokines in Overweight Men

BACKGROUND

The aim of this study was to investigate the effects of whole-body electrical muscle stimulation (WB-EMS) training on inflammatory and anti-inflammatory cytokines in overweight men.

METHODS

We divided 30 participants into EMS and control groups. The training program for the EMS group comprised 20 WB-EMS sessions (7 weeks, three sessions per week).

RESULTS

The results showed that EMS training caused significant increase in interferon γ (P<0.001) and interleukin 10 (IL-10; P<0.01) and significant decrease in IL-17 and IL-23 (P<0.05). Also, the lipid profile showed significant positive changes in the EMS training group.

CONCLUSION

EMS training, a novel exercise method that uses electric stimulation, can affect the levels of various cytokines that are involved in inflammation and immunity. EMS training can have both beneficial and harmful effects on the body depending on the type and balance of involved cytokines.

JNJ-77242113, a highly potent, selective peptide targeting the IL-23 receptor, provides robust IL-23 pathway inhibition upon oral dosing in rats and humans

The interleukin (IL)-23 pathway is a pathogenic driver in psoriasis, psoriatic arthritis, and inflammatory bowel disease. Currently, no oral therapeutics selectively target this pathway. JNJ-77242113 is a peptide targeting the IL-23 receptor with high affinity (KD: 7.1 pM). In human cells, JNJ-77242113 potently and selectively inhibited proximal IL-23 signaling (IC50: 5.6 pM) without impacting IL-12 signaling. JNJ-77242113 inhibited IL-23-induced interferon (IFN)γ production in NK cells, and in blood from healthy donors and psoriasis patients (IC50: 18.4, 11 and 9 pM, respectively). In a rat trinitrobenzene sulfonic acid-induced colitis model, oral JNJ-77242113 attenuated disease parameters at doses ≥ 0.3 mg/kg/day. Pharmacologic activity beyond the gastrointestinal tract was also demonstrated. In blood from rats receiving oral JNJ-77242113, dose-dependent inhibition of ex vivo IL-23-stimulated IL-17A production was observed. In an IL-23-induced rat skin inflammation model, JNJ-77242113 inhibited IL-23-induced skin thickening and IL-17A, -17F and -22 gene induction. Oral dosing of JNJ-77242113 in healthy human volunteers inhibited ex vivo IL-23-stimulated IFNγ production in whole blood. Thus, JNJ-77242113 provided selective, systemic IL-23 pathway inhibition in preclinical models which translated to pharmacodynamic activity in healthy human volunteers, supporting the potential for JNJ-77242113 as a selective oral therapy for IL-23-driven immune-mediated diseases.

Chemotherapy-induced high expression of IL23A enhances efficacy of anti-PD-1 therapy in TNBC by co-activating the PI3K-AKT signaling pathway of CTLs

Treatment of advanced triple-negative breast cancer (TNBC) is a great challenge in clinical practice. The immune checkpoints are a category of immunosuppressive molecules that cancer could hijack and impede anti-tumor immunity. Targeting immune checkpoints, such as anti-programmed cell death 1 (PD-1) therapy, is a promising therapeutic strategy in TNBC. The efficacy and safety of PD-1 monoclonal antibody (mAb) with chemotherapy have been validated in TNBC patients. However, the precise mechanisms underlying the synergistic effect of chemotherapy and anti-PD-1 therapy have not been elucidated, causing the TNBC patients that might benefit from this combination regimen not to be well selected. In the present work, we found that IL-23, an immunological cytokine, is significantly upregulated after chemotherapy in TNBC cells and plays a vital role in enhancing the anti-tumor immune response of cytotoxic T cells (CTLs), especially in combination with PD-1 mAb. In addition, the combination of IL-23 and PD-1 mAb could synergistically inhibit the expression of Phosphoinositide-3-Kinase Regulatory Subunit 1 (PIK3R1), which is a regulatory subunit of PI3K and inhibit p110 activity, and promote phosphorylation of AKT in TNBC-specific CTLs. Our findings might provide a molecular marker that could be used to predict the effects of combination chemotherapy therapy and PD-1 mAb in TNBC.

Anti-PD-1 cis-delivery of low-affinity IL-12 activates intratumoral CD8+T cells for systemic antitumor responses

Immune checkpoint blockade (ICB) therapies function by alleviating immunosuppression on tumor-infiltrating lymphocytes (TILs) but are often insufficient to fully reactivate these dysfunctional TILs. Although interleukin 12 (IL-12) has been used in combination with ICB to improve efficacy, this remains limited by severe toxicity associated with systemic administration of this cytokine. Here, we engineer a fusion protein composed of an anti-PD-1 antibody and a mouse low-affinity IL-12 mutant-2 (αPD1-mIL12mut2). Systemic administration of αPD1-mIL12mut2 displays robust antitumor activities with undetectable toxicity. Mechanistically, αPD1-mIL12mut2 preferentially activates tumor-infiltrating PD-1+CD8+T cells via high-affinity αPD-1 mediated cis-binding of low-affinity IL-12. Additionally, αPD1-mIL12mut2 treatment exerts an abscopal effect to suppress distal tumors, as well as metastasis. Collectively, αPD1-mIL12mut2 treatment induces robust systemic antitumor responses with reduced side effects.

IL-23 past, present, and future: a roadmap to advancing IL-23 science and therapy

Interleukin (IL)-23, an IL-12 cytokine family member, is a hierarchically dominant regulatory cytokine in a cluster of immune-mediated inflammatory diseases (IMIDs), including psoriasis, psoriatic arthritis, and inflammatory bowel disease. We review IL-23 biology, IL-23 signaling in IMIDs, and the effect of IL-23 inhibition in treating these diseases. We propose studies to advance IL-23 biology and unravel differences in response to anti-IL-23 therapy. Experimental evidence generated from these investigations could establish a novel molecular ontology centered around IL-23-driven diseases, improve upon current approaches to treating IMIDs with IL-23 inhibition, and ultimately facilitate optimal identification of patients and, thereby, outcomes.

Identification of the grass carp interleukin-23 receptor and its proinflammatory role in intestinal inflammation

The interleukin 23 receptor (IL-23R) is associated with a variety of inflammatory diseases in humans and other mammals. However, whether IL-23R is involved in inflammatory diseases in teleost fish is less understood. Thus, to investigate the potential involvement of IL-23R in fish inflammatory diseases, the full-length cDNA of IL-23R from grass carp Ctenopharyngodon idella was cloned and used to generate a recombinant protein (rgcIL-23R) containing the extracellular domain of IL-23R, against which a polyclonal antibody (rgcIL-23R pAb) was then developed. qPCR analysis revealed that IL-23R mRNA was significantly upregulated in most grass carp tissues in response to infection with Gram-negative Aeromonas hydrophila. Treatment with rgcIL-23R significantly induced IL-17A/F1 expression in C. idella kidney (CIK) cells. By contrast, knockdown of IL-23R caused significant decreases in IL-23R, STAT3, and IL-17N expression in CIK cells after lipopolysaccharide (LPS) stimulation. Similarly, rgcIL-23R pAb treatment effectively inhibited the LPS-induced increase in the expression of IL-23 subunit genes and those of the IL-23/IL-17 pathway in CIK cells. Furthermore, intestinal symptoms identical to those caused by A. hydrophila were induced by anal intubation with rgcIL-23R, but suppressed by rgcIL-23R pAb. Therefore, these results suggest that IL-23R has a crucial role in the regulation of intestinal inflammation and, thus, is a promising target for controlling inflammatory diseases in farmed fish.

Structures of complete extracellular receptor assemblies mediated by IL-12 and IL-23

Cell-surface receptor complexes mediated by pro-inflammatory interleukin (IL)-12 and IL-23, both validated therapeutic targets, are incompletely understood due to the lack of structural insights into their complete extracellular assemblies. Furthermore, there is a paucity of structural details describing the IL-12-receptor interaction interfaces, in contrast to IL-23-receptor complexes. Here we report structures of fully assembled mouse IL-12/human IL-23-receptor complexes comprising the complete extracellular segments of the cognate receptors determined by electron cryo-microscopy. The structures reveal key commonalities but also surprisingly diverse features. Most notably, whereas IL-12 and IL-23 both utilize a conspicuously presented aromatic residue on their α-subunit as a hotspot to interact with the N-terminal Ig domain of their high-affinity receptors, only IL-12 juxtaposes receptor domains proximal to the cell membrane. Collectively, our findings will help to complete our understanding of cytokine-mediated assemblies of tall cytokine receptors and will enable a cytokine-specific interrogation of IL-12/IL-23 signaling in physiology and disease.

Interleukin 23 receptor: Expression and regulation in immune cells

The importance of IL-23 and its specific receptor, IL-23R, in the pathogenesis of several chronic inflammatory diseases has been established, but the underlying pathological mechanisms are not fully understood. This review focuses on IL-23R expression and regulation in immune cells.

Assembly-dependent Structure Formation Shapes Human Interleukin-23 versus Interleukin-12 Secretion

Interleukin 12 (IL-12) family cytokines connect the innate and adaptive branches of the immune system and regulate immune responses. A unique characteristic of this family is that each member is anα:βheterodimer. For human αsubunits it has been shown that they depend on theirβsubunit for structure formation and secretion from cells. Since subunits are shared within the family and IL-12 as well as IL-23 use the same βsubunit, subunit competition may influence cytokine secretion and thus downstream immunological functions. Here, we rationally design a folding-competent human IL-23α subunit that does not depend on itsβsubunit for structure formation. This engineered variant still forms a functional heterodimeric cytokine but shows less chaperone dependency and stronger affinity in assembly with its βsubunit. It forms IL-23 more efficiently than its natural counterpart, skewing the balance of IL-12 and IL-23 towards more IL-23 formation. Together, our study shows that folding-competent human IL-12 familyαsubunits are obtainable by only few mutations and compatible with assembly and function of the cytokine. These findings might suggest that human α subunits have evolved for assembly-dependent folding to maintain and regulate correct IL-12 family member ratios in the light of subunit competition.

Human interleukin-12α and EBI3 are cytokines with anti-inflammatory functions

Interleukins are secreted proteins that regulate immune responses. Among these, the interleukin 12 (IL-12) family holds a central position in inflammatory and infectious diseases. Each family member consists of an α and a β subunit that together form a composite cytokine. Within the IL-12 family, IL-35 remains particularly ill-characterized on a molecular level despite its key role in autoimmune diseases and cancer. Here we show that both IL-35 subunits, IL-12α and EBI3, mutually promote their secretion from cells but are not necessarily secreted as a heterodimer. Our data demonstrate that IL-12α and EBI3 are stable proteins in isolation that act as anti-inflammatory molecules. Both reduce secretion of proinflammatory cytokines and induce the development of regulatory T cells. Together, our study reveals IL-12α and EBI3, the subunits of IL-35, to be functionally active anti-inflammatory immune molecules on their own. This extends our understanding of the human cytokine repertoire as a basis for immunotherapeutic approaches.

Modeling of the human interleukin 12:receptor complex allows to engineer attenuated cytokine variants

Interleukin 12 (IL-12) plays major roles in immune defense against intracellular pathogens. By activating T cells and increasing antigen presentation, it is also a very potent anti-tumor molecule. Strong immune activation and systemic toxicity, however, so far limit its potential therapeutic use. Building on recent experimental structures of IL-12 related cytokine:receptor complexes, we here provide a high-resolution computational model of the human IL-12:receptor complex. We design attenuated IL-12 variants with lower receptor binding affinities based on molecular dynamics simulations, and subsequently validate them experimentally. These variants show reduced activation of natural killer cells while maintaining T cell activation. This immunological signature is important to develop IL-12 for cancer treatment, where natural killer cells contribute to severe side-effects. Taken together, our study provides detailed insights into structure and dynamics of the human IL-12:receptor complex and leverages them for engineering attenuated variants to elicit fewer side-effects while maintaining relevant biological activity.

Psoriasis and Leprosy: An Arcane Relationship

Purpose

Psoriasis (Ps) and leprosy are chronic inflammatory skin disorders, characterised by enhanced innate and adaptive immunity. Ps and leprosy rarely coexist. The molecular immune mechanism of the Ps and leprosy rarely coexistence is unclear.

Patients and Methods

RNA-sequencing (RNA-seq) was performed on 20 patients with Ps, 5 adults with lepromatous leprosy (L-lep), and 5 patients with tuberculoid leprosy (T-lep) to analyse the differentially expressed genes (DEGs) between them. Moreover, the biological mechanism of Ps and leprosy was explored by Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, Gene Ontology (GO) analysis, Gene Set Enrichment Analysis analysis, and protein-protein interaction (PPI) analyses. Finally, 13 DEGs of 10 skin biopsies of Ps patients, 6 samples of L-lep patients, 6 samples of T-lep patients and 5 healthy controls were confirmed by quantitative real-time polymerase chain reaction (qRT-PCR).

Results

The PPI network was constructed and primarily associated with immune response, IL-17 signalling, and Toll-like receptor pathway between Ps and leprosy. Th17 markers (interleukin (IL)-19, IL-20, IL-36A, IL-36G, IL-22, IL-17A, and lipocalin-2 (LCN2) had higher expression in Ps than in L-lep and T-lep, whereas macrophage biomarkers (CLEC4E and TREM2), SPP1, and dendritic cell (DC)-related hallmarks (ITGAX) and TNF-a had significantly lower expression across Ps and T-lep than in L-lep.

Conclusion

To put it simply, Ps patients with IL-17A, IL-19, IL-20, IL-36A, IL-36G, and IL-22 in conjunction with LCN2 with up-graduated expression might be not susceptible to L-lep. However, high levels of CLEC4E, TREM2, and SPP1 in L-lep patients indicated that they unlikely suffered from Ps.

Use of NanoBiT and NanoBRET to characterise interleukin-23 receptor dimer formation in living cells

BACKGROUND AND PURPOSE

Interleukin-23 (IL-23) and its receptor are important drug targets for the treatment of auto-inflammatory diseases. IL-23 binds to a receptor complex composed of two single transmembrane spanning proteins IL23R and IL12Rβ1. In this study, we aimed to gain further understanding of how ligand binding induces signalling of IL-23 receptor complexes using the proximity-based techniques of NanoLuc Binary Technology (NanoBiT) and Bioluminescence Resonance Energy Transfer (BRET).

EXPERIMENTAL APPROACH

To monitor the formation of IL-23 receptor complexes, we developed a split luciferase (NanoBiT) assay whereby heteromerisation of receptor subunits can be measured through luminescence. The affinity of NanoBiT complemented complexes for IL-23 was measured using NanoBRET, and cytokine-induced signal transduction was measured using a phospho-STAT3 AlphaLISA assay.

KEY RESULTS

NanoBiT measurements demonstrated that IL-23 receptor complexes formed to an equal degree in the presence and absence of ligand. NanoBRET measurements confirmed that these complexes bound IL-23 with a picomolar binding affinity. Measurement of STAT3 phosphorylation demonstrated that pre-formed IL-23 receptor complexes induced signalling following ligand binding. It was also demonstrated that synthetic ligand-independent signalling could be induced by high affinity (HiBit) but not low affinity (SmBit) NanoBiT crosslinking of the receptor N-terminal domains.

CONCLUSIONS AND IMPLICATIONS

These results indicate that receptor complexes form prior to ligand binding and are not sufficient to induce signalling alone. Our findings indicate that IL-23 induces a conformational change in heteromeric receptor complexes, to enable signal transduction. These observations have direct implications for drug discovery efforts to target the IL-23 receptor.

Characterisation of IL-23 receptor antagonists and disease relevant mutants using fluorescent probes

Association of single nucleotide polymorphisms in the IL-23 receptor with several auto-inflammatory diseases, led to the heterodimeric receptor and its cytokine-ligand IL-23, becoming important drug targets. Successful antibody-based therapies directed against the cytokine have been licenced and a class of small peptide antagonists of the receptor have entered clinical trials. These peptide antagonists may offer therapeutic advantages over existing anti-IL-23 therapies, but little is known about their molecular pharmacology. In this study, we use a fluorescent version of IL-23 to characterise antagonists of the full-length receptor expressed by living cells using a NanoBRET competition assay. We then develop a cyclic peptide fluorescent probe, specific to the IL23p19:IL23R interface and use this molecule to characterise further receptor antagonists. Finally, we use the assays to study the immunocompromising C115Y IL23R mutation, demonstrating that the mechanism of action is a disruption of the binding epitope for IL23p19.

Human IL-23 is essential for IFN-γ-dependent immunity to mycobacteria

Patients with autosomal recessive (AR) IL-12p40 or IL-12Rβ1 deficiency display Mendelian susceptibility to mycobacterial disease (MSMD) due to impaired IFN-γ production and, less commonly, chronic mucocutaneous candidiasis (CMC) due to impaired IL-17A/F production. We report six patients from four kindreds with AR IL-23R deficiency. These patients are homozygous for one of four different loss-of-function IL23R variants. All six patients have a history of MSMD, but only two suffered from CMC. We show that IL-23 induces IL-17A only in MAIT cells, possibly contributing to the incomplete penetrance of CMC in patients unresponsive to IL-23. By contrast, IL-23 is required for both baseline and Mycobacterium-inducible IFN-γ immunity in both Vδ2+ γδ T and MAIT cells, probably contributing to the higher penetrance of MSMD in these patients. Human IL-23 appears to contribute to IL-17A/F-dependent immunity to Candida in a single lymphocyte subset but is required for IFN-γ-dependent immunity to Mycobacterium in at least two lymphocyte subsets.

A comprehensive set of ER protein disulfide isomerase family members supports the biogenesis of proinflammatory interleukin 12 family cytokines

Cytokines of the interleukin 12 (IL-12) family are assembled combinatorially from shared α and β subunits. A common theme is that human IL-12 family α subunits remain incompletely structured in isolation until they pair with a designate β subunit. Accordingly, chaperones need to support and control specific assembly processes. It remains incompletely understood, which chaperones are involved in IL-12 family biogenesis. Here, we site-specifically introduce photocrosslinking amino acids into the IL-12 and IL-23 α subunits (IL-12α and IL-23α) for stabilization of transient chaperone-client complexes for mass spectrometry. Our analysis reveals that a large set of endoplasmic reticulum chaperones interacts with IL-12α and IL-23α. Among these chaperones, we focus on protein disulfide isomerase (PDI) family members and reveal IL-12 family subunits to be clients of several incompletely characterized PDIs. We find that different PDIs show selectivity for different cysteines in IL-12α and IL-23α. Despite this, PDI binding generally stabilizes unassembled IL-12α and IL-23α against degradation. In contrast, α:β assembly appears robust, and only multiple simultaneous PDI depletions reduce IL-12 secretion. Our comprehensive analysis of the IL-12/IL-23 chaperone machinery reveals a hitherto uncharacterized role for several PDIs in this process. This extends our understanding of how cells accomplish the task of specific protein assembly reactions for signaling processes. Furthermore, our findings show that cytokine secretion can be modulated by targeting specific endoplasmic reticulum chaperones.

Structural basis of activation and antagonism of receptor signaling mediated by interleukin-27

Interleukin-27 (IL-27) uniquely assembles p28 and EBI3 subunits to a heterodimeric cytokine that signals via IL-27Rα and gp130. To provide the structural framework for receptor activation by IL-27 and its emerging therapeutic targeting, we report here crystal structures of mouse IL-27 in complex with IL-27Rα and of human IL-27 in complex with SRF388, a monoclonal antibody undergoing clinical trials with oncology indications. One face of the helical p28 subunit interacts with EBI3, while the opposite face nestles into the interdomain elbow of IL-27Rα to juxtapose IL-27Rα to EBI3. This orients IL-27Rα for paired signaling with gp130, which only uses its immunoglobulin domain to bind to IL-27. Such a signaling complex is distinct from those mediated by IL-12 and IL-23. The SRF388 binding epitope on IL-27 overlaps with the IL-27Rα interaction site explaining its potent antagonistic properties. Collectively, our findings will facilitate the mechanistic interrogation, engineering, and therapeutic targeting of IL-27.

Colorectal Cancer in Ulcerative Colitis: Mechanisms, Surveillance and Chemoprevention

Patients with ulcerative colitis (UC) are at a two- to three-fold increased risk of developing colorectal cancer (CRC) than the general population based on population-based data. UC-CRC has generated a series of clinical problems, which are reflected in its worse prognosis and higher mortality than sporadic CRC. Chronic inflammation is a significant contributor to the development of UC-CRC, so comprehending the relationship between the proinflammatory factors and epithelial cells together with downstream signaling pathways is the core to elucidate the mechanisms involved in developing of CRC. Clinical studies have shown the importance of early prevention, detection and management of CRC in patients with UC, and colonoscopic surveillance at regular intervals with multiple biopsies is considered the most effective way. The use of endoscopy with targeted biopsies of visible lesions has been supported in most populations. In contrast, random biopsies in patients with high-risk characteristics have been suggested during surveillance. Some of the agents used to treat UC are chemopreventive, the effects of which will be examined in cancers in UC in a population-based setting. In this review, we outline the current state of potential risk factors and chemopreventive recommendations in UC-CRC, with a specific focus on the proinflammatory mechanisms in promoting CRC and evidence for personalized surveillance.

Biogenesis and engineering of interleukin 12 family cytokines

Interleukin 12 (IL-12) family cytokines are secreted proteins that regulate immune responses. Each family member is a heterodimer and nature uses shared building blocks to assemble the functionally distinct IL-12 cytokines. In recent years we have gained insights into the molecular principles and cellular regulation of IL-12 family biogenesis. For each of the family members, generally one subunit depends on its partner to acquire its native structure and be secreted from immune cells. If unpaired, molecular chaperones retain these subunits in cells. This allows cells to regulate and control secretion of the highly potent IL-12 family cytokines. Molecular insights gained into IL-12 family biogenesis, structure, and function now allow us to engineer IL-12 family cytokines to develop novel immunotherapeutic approaches.

Interleukin-23 in the Pathogenesis of Inflammatory Bowel Disease and Implications for Therapeutic Intervention

The interleukin-23 [IL-23] cytokine, derived predominantly from macrophages and dendritic cells in response to microbial stimulation, has emerged as a critical promoter of chronic intestinal inflammation. Genome-wide association studies linking variants in IL23R to disease protection, bolstered by experimental evidence from colitis models, and the successful application of therapies against the IL-12/IL-23 shared p40 subunit in the treatment of inflammatory bowel disease [IBD] all provide compelling evidence of a crucial role for IL-23 in disease pathogenesis. Moreover, targeting the p19 subunit specific for IL-23 has shown considerable promise in recent phase 2 studies in IBD. The relative importance of the diverse immunological pathways downstream of IL-23 in propagating mucosal inflammation in the gut, however, remains contentious. Here we review current understanding of IL-23 biology and explore its pleiotropic effects on T cells, and innate lymphoid, myeloid and intestinal epithelial cells in the context of the pathogenesis of IBD. We furthermore discuss these pathways in the light of recent evidence from clinical trials and indicate emerging targets amenable to therapeutic intervention and translation into clinical practice.

Antibody-mediated blockade of the IL23 receptor destabilizes intratumoral regulatory T cells and enhances immunotherapy

Regulatory T cells (Treg) can impede antitumor immunity and currently represent a major obstacle to effective cancer immunotherapy. Targeting tumor-infiltrating regulatory Treg while sparing systemic Treg represents an optimal approach to this problem. Here, we provide evidence that the interleukin 23 receptor (IL23R) expressed by tumor-infiltrating Treg promotes suppressive activity. Disruption of the IL23R results in increased responsiveness of destabilized Treg to the IL12 cytokine, the production of γ-interferon, and the recruitment of CD8 T cells that inhibit tumor growth. Since the Treg destabilization pathway that is initiated by IL23R blockade is distinct and independent from the destabilization pathway coupled to glucocorticoid-induced TNFR-related protein (GITR) activation, we examined the impact of the coordinate induction of the two destabilization pathways on antitumor immune responses. Combined GITR and IL23R antibody treatment of mice inoculated with MC38 tumors resulted in robust and synergistic antitumor responses. These findings indicate that the delineation of independent Treg destabilization pathways may allow improved approaches to the development of combination immunotherapy for cancers.

Structural basis of human IL-18 sequestration by the decoy receptor IL-18 binding protein (IL-18BP) in inflammation and tumor immunity

Human Interleukin-18 (IL-18) is an omnipresent proinflammatory cytokine of the IL-1 family with central roles in autoimmune and inflammatory diseases and serves as a staple biomarker in the evaluation of inflammation in physiology and disease, including the inflammatory phase of COVID-19. The sequestration of IL-18 by its soluble decoy receptor IL-18-Binding Protein (IL-18BP) is critical to the regulation of IL-18 activity. Since an imbalance in expression and circulating levels of IL-18 is associated with disease, structural insights into how IL-18BP outcompetes binding of IL-18 by its cognate cell-surface receptors are highly desirable; however, the structure of human IL-18BP in complex with IL-18 has been elusive. Here, we elucidate the sequestration mechanism of human IL-18 mediated by IL-18BP based on the crystal structure of the IL-18:IL-18BP complex. These detailed structural snapshots reveal the interaction landscape leading to the ultra-high affinity of IL-18BP toward IL-18 and identify substantial differences with respect to previously characterized complexes of IL-18 with IL-18BP of viral origin. Furthermore, our structure captured a fortuitous higher-order assembly between IL-18 and IL-18BP coordinated by a disulfide-bond distal to the binding surface connecting IL-18 and IL-18BP molecules from different complexes, resulting in a novel tetramer with 2:2 stoichiometry. This tetrapartite assembly was found to restrain IL-18 activity more effectively than the canonical 1:1 complex. Collectively, our findings provide a framework for innovative, structure-driven therapeutic strategies and further functional interrogation of IL-18 in physiology and disease.

Probing the binding of interleukin-23 to individual receptor components and the IL-23 heteromeric receptor complex in living cells using NanoBRET

Interleukin-23 (IL-23) is a pro-inflammatory cytokine involved in the host defense against pathogens but is also implicated in the development of several autoimmune disorders. The IL-23 receptor has become a key target for drug discovery, but the exact mechanism of the receptor ligand interaction remains poorly understood. In this study the affinities of IL-23 for its individual receptor components (IL23R and IL12Rβ1) and the heteromeric complex formed between them have been measured in living cells using NanoLuciferase-tagged full-length proteins. Here, we demonstrate that TAMRA-tagged IL-23 has a greater than 7-fold higher affinity for IL12Rβ1 than IL23R. However, in the presence of both receptor subunits, IL-23 affinity is increased more than three orders of magnitude to 27 pM. Furthermore, we show that IL-23 induces a potent change in the position of the N-terminal domains of the two receptor subunits, consistent with a conformational change in the heteromeric receptor structure.

Cytokine Receptors-Regulators of Antimycobacterial Immune Response

Cytokine receptors are critical regulators of the antimycobacterial immune response, playing a key role in initiating and coordinating the recruitment and activation of immune cells during infection. They recognize and bind specific cytokines and are involved in inducing intracellular signal transduction pathways that regulate a diverse range of biological functions, including proliferation, differentiation, metabolism and cell growth. Due to mutations in cytokine receptor genes, defective signaling may contribute to increased susceptibility to mycobacteria, allowing the pathogens to avoid killing and immune surveillance. This paper provides an overview of cytokine receptors important for the innate and adaptive immune responses against mycobacteria and discusses the implications of receptor gene defects for the course of mycobacterial infection.

Antibody variable sequences have a pronounced effect on cellular transport and plasma half-life

Monoclonal IgG antibodies are the fastest growing class of biologics, but large differences exist in their plasma half-life in humans. Thus, to design IgG antibodies with favorable pharmacokinetics, it is crucial to identify the determinants of such differences. Here, we demonstrate that the variable region sequences of IgG antibodies greatly affect cellular uptake and subsequent recycling and rescue from intracellular degradation by endothelial cells. When the variable sequences are masked by the cognate antigen, it influences both their transport behavior and binding to the neonatal Fc receptor (FcRn), a key regulator of IgG plasma half-life. Furthermore, we show how charge patch differences in the variable domains modulate both binding and transport properties and that a short plasma half-life, due to unfavorable charge patches, may partly be overcome by Fc-engineering for improved FcRn binding.

•

IgG variable region sequences greatly affect cellular uptake and recycling

•

Variable region charge patches affect FcRn binding and transport

•

The presence of cognate antigen modulates cellular transport and FcRn binding

•

Fc-engineering for improved FcRn binding can overcome unfavorable charge patches

A novel cytokine consisting of the p40 and EBI3 subunits suppresses experimental autoimmune arthritis via reciprocal regulation of Th17 and Treg cells

OBJECTIVE

The interleukin (IL)-12 cytokine family is closely related to the development of T helper cells, which are responsible for autoimmune disease enhancement or suppression. IL-12 family members are generally heterodimers and share three α-subunits (p35, p19, and p28) and two β-subunits (p40 and EBI3). However, a β-sheet p40 homodimer has been shown to exist and antagonize IL-12 and IL-23 signaling ¹. Therefore, we assumed the existence of a p40-EBI3 heterodimer in nature and sought to investigate its role in immune regulation.

METHODS

The presence of the p40-EBI3 heterodimer was confirmed by ELISA, immunoprecipitation, and western blotting. A p40-EBI3 vector and p40-EBI3-Fc protein were synthesized to confirm the immunological role of this protein in mice with collagen-induced arthritis (CIA). The anti-inflammatory effects of p40-EBI3 were analyzed with regard to clinical, histological, and immune cell-regulating features in mice with CIA.

RESULTS

Clinical arthritis scores and the expression levels of proinflammatory cytokines (e.g., IL-17, IL-1β, IL-6, and TNF-α) were significantly attenuated in p40-EBI3-overexpressing and p40-EBI3-Fc-treated mice with CIA compared to vehicle-treated mice with CIA. Structural joint damage and vessel formation-related gene expression were also reduced by p40-EBI3 heterodimer treatment. In vitro, the p40-EBI3-Fc protein significantly suppressed the differentiation of Th17 cells and reciprocally induced CD4⁺CD25⁺Foxp3⁺ (regulatory T) cells. p40-EBI3 also inhibited osteoclast formation in a concentration-dependent manner.

CONCLUSION

In this study, p40-EBI3 ameliorated proinflammatory conditions both in vivo and in vitro. We propose that p40-EBI3 is a novel anti-inflammatory cytokine involved in suppressing the immune response through the expansion of Treg cells and suppression of Th17 cells and osteoclastogenesis.

Tryptophan (W) at position 37 of murine IL-12/IL-23 p40 is mandatory for binding to IL-12Rβ1 and subsequent signal transduction

Interleukin (IL)-12 and IL-23 are composite cytokines consisting of p35/p40 and p19/p40, respectively, which signal via the common IL-12 receptor β1 (IL-12Rβ1) and the cytokine-specific receptors IL-12Rβ2 and IL-23R. Previous data showed that the p40 component interacts with IL-12Rβ1, whereas p19 and p35 subunits solely bind to IL-23R and IL-12Rβ2, resulting in tetrameric signaling complexes. In the absence of p19 and p35, p40 forms homodimers and may induce signaling via IL-12Rβ1 homodimers. The critical amino acids of p19 and p35 required for binding to IL-23R and IL-12Rβ2 are known, and two regions of p40 critical for binding to IL-12Rβ1 have recently been identified. In order to characterize the involvement of the N-terminal region of p40 in binding to IL-12Rβ1, we generated deletion variants of the p40-p19 fusion cytokine. We found that an N-terminal deletion variant missing amino acids M23 to P39 failed to induce IL-23-dependent signaling and did not bind to IL-12Rβ1, whereas binding to IL-23R was maintained. Amino acid replacements showed that p40W37K largely abolished IL-23-induced signal transduction and binding to IL-12Rβ1, but not binding to IL-23R. Combining p40W37K with D36K and T38K mutations eliminated the biological activity of IL-23. Finally, homodimeric p40D36K/W37K/T38K did not interact with IL-12Rβ1, indicating binding of homodimeric p40 to IL-12Rβ1 is comparable to the interaction of IL-23/IL-12 and IL-12Rβ1. In summary, we have defined D36, W37, and T38 as hotspot amino acids for the interaction of IL-12/IL-23 p40 with IL-12Rβ1. Structural insights into cytokine–cytokine receptor binding are important to develop novel therapeutic strategies.

Clinical Implementation of Biologics and Small Molecules in the Treatment of Hidradenitis Suppurativa

Hidradenitis suppurativa (HS) is a chronic, recurrent, auto-inflammatory skin disease originating from the hair follicles. The typical inflammatory nodules, abscesses, and draining sinus tracts (tunnels) are characterized by a massive influx of neutrophils, macrophages, B-cells, plasma cells, T helper (Th)1, Th17 cells and upregulation of pro-inflammatory cytokines such as IL-1, IL-17, IL-12/23, and TNF-α. Over the last decades, several clinical trials evaluated the clinical efficacy of different biologics targeting these pro-inflammatory cytokines, in particular TNF-α and IL-1. However, adalimumab is still the only registered drug for HS. This review discusses biologics and small molecules with high level of evidence for their clinical application, provides guidance on when and how to use these biologics and small molecules in clinical practice, and elaborates on the combination with medical and surgical treatment options beyond the current guidelines. Furthermore this review provides an overview of potential biologics and small molecules currently under investigation for novel targets in HS such as IL-36, C5a, Janus kinase family members, CD-40, LTA4 and CXCR1/2.

Current status and relevance of single nucleotide polymorphisms in IL-6-/IL-12-type cytokine receptors

Cytokines control immune related events and are critically involved in a plethora of patho-physiological processes including autoimmunity and cancer development. In rare cases, single nucleotide polymorphisms (SNPs) or single nucleotide variations (SNVs) in cytokine receptors eventually cause detrimental ligand-independent, constitutive activation of signal transduction. Most SNPs have, however, no or only marginal influences on gene expression, protein stability, localization and function and thereby only slightly affecting pathogenesis probability. The SNP database (dbSNP) is an archive for a broad collection of polymorphisms in which SNPs are categorized and marked with a locus accession number "reference SNP" (rs). Here, we engineered an algorithm to directly align dbSNP information to DNA and protein sequence information to clearly illustrate a genetic SNP landscape exemplified for all tall cytokine receptors of the IL-6/IL-12 family, including IL-23R, IL-12Rβ1, IL-12Rβ2, gp130, LIFR, OSMR and WSX-1. This information was complemented by a comprehensive literature summary and structural insights of relevant disease-causing SNPs in cytokine/cytokine receptor interfaces. In summary, we present a general strategy with potential to apply to other cytokine receptor networks.

IL-23 receptor deficiency results in lower bone mass via indirect regulation of bone formation

The IL-23 receptor (IL-23R) signaling pathway has pleiotropic effects on the differentiation of osteoclasts and osteoblasts, since it can inhibit or stimulate these processes via different pathways. However, the potential role of this pathway in the regulation of bone homeostasis remains elusive. Therefore, we studied the role of IL-23R signaling in physiological bone remodeling using IL-23R deficient mice. Using µCT, we demonstrate that 7-week-old IL-23R^−/− mice have similar bone mass as age matched littermate control mice. In contrast, 12-week-old IL-23R^−/− mice have significantly lower trabecular and cortical bone mass, shorter femurs and more fragile bones. At the age of 26 weeks, there were no differences in trabecular bone mass and femur length, but most of cortical bone mass parameters remain significantly lower in IL-23R^−/− mice. In vitro osteoclast differentiation and resorption capacity of 7- and 12-week-old IL-23R^−/− mice are similar to WT. However, serum levels of the bone formation marker, PINP, are significantly lower in 12-week-old IL-23R^−/− mice, but similar to WT at 7 and 26 weeks. Interestingly, Il23r gene expression was not detected in in vitro cultured osteoblasts, suggesting an indirect effect of IL-23R. In conclusion, IL-23R deficiency results in temporal and long-term changes in bone growth via regulation of bone formation.

Anti-IL-23 exerted protective effects on cerebral ischemia-reperfusion injury through JAK2/STAT3 signaling pathway

Ischemia-reperfusion frequently occurs in ischemic cerebral vascular disease, during which the inflammatory signaling plays essential roles. The aim of this study was to discover the efficacy of the antibody to a key immune cytokine IL-23 (anti-IL-23) for the therapy of cerebral ischemia-reperfusion injury. We established the cerebral ischemia-reperfusion injury model by middle cerebral artery occlusion (MCAO). Anti-IL-23 injection attenuated lesions indicated by histology study. RT-PCR and Western blot were employed to detect the mRNA and protein expression of JAK2 and STAT3 after anti-IL-23 treatment. ELISA was utilized to measure the levels of MDA (malondialdehyde) and superoxide dismutase (SOD). Moreover, curcumin and IL-6 were implicated in the endogenous intervention of IL-23 signaling in vivo. Our data demonstrated that the treatment of anti-IL-23 might transcriptionally activate the classic immune pathway in the brain. Anti-IL-23 augmented phosphorylation levels of both JAK2 and STAT3, suggesting the amplification signaling of JAK/STAT after exogenous IL-23 intervention. Anti-IL-23 reduced ROS molecules of STAT downstream in the serum and brain. It also alleviated the injury by bringing down levels of MDA and SOD in the serum. JAK2 inhibitor could abolish the effect of anti-IL-23 whereas JAK3 ameliorated the injury. The combination of anti-IL-23 and JAK3i could reduce infarct volume more effectively. In summary, this study indicated that anti-IL-23 had protective effects against cerebral ischemia-reperfusion injury by targeting the immune specific JAK2-STAT3 in JAK/STAT pathway.

Engineering and crystal structure of a monomeric FLT3 ligand variant

The overarching paradigm for the activation of class III and V receptor tyrosine kinases (RTKs) prescribes cytokine-mediated dimerization of the receptor ectodomains and homotypic receptor-receptor interactions. However, structural studies have shown that the hematopoietic receptor FLT3, a class III RTK, does not appear to engage in such receptor-receptor contacts, despite its efficient dimerization by dimeric FLT3 ligand (FL). As part of efforts to better understand the intricacies of FLT3 activation, we sought to engineer a monomeric FL. It was found that a Leu27Asp substitution at the dimer interface of the cytokine led to a stable monomeric cytokine (FLL27D) without abrogation of receptor binding. The crystal structure of FLL27D at 1.65 Å resolution revealed that the introduced point mutation led to shielding of the hydrophobic footprint of the dimerization interface in wild-type FL without affecting the conformation of the FLT3 binding site. Thus, FLL27D can serve as a monomeric FL variant to further interrogate the assembly mechanism of extracellular complexes of FLT3 in physiology and disease.

Cytokines that Modulate the Differentiation of Th17 Cells in Autoimmune Uveitis

Increasing evidence has suggested that T helper 17 (Th17) cells play a central role in the pathogenesis of ocular immune disease. The association between pathogenic Th17 cells and the development of uveitis has been confirmed in experimental and clinical studies. Several cytokines affect the initiation and stabilization of the differentiation of Th17 cells. Therefore, understanding the mechanism of related cytokines in the differentiation of Th17 cells is important for exploring the pathogenesis and the potential therapeutic targets of uveitis. This article briefly describes the structures, mechanisms, and targeted drugs of cytokines-including interleukin (IL)-6, transforming growth factor-β1 (TGF-β1), IL-1β, IL-23, IL-27, IL-35, IL-2, IL-4, IL-21, and interferon (IFN)-γ-which have an important influence on the differentiation of Th17 cells and discusses their potential as therapeutic targets for treating autoimmune uveitis.

Cell-penetrating Alphabody protein scaffolds for intracellular drug targeting

The therapeutic scope of antibody and nonantibody protein scaffolds is still prohibitively limited against intracellular drug targets. Here, we demonstrate that the Alphabody scaffold can be engineered into a cell-penetrating protein antagonist against induced myeloid leukemia cell differentiation protein MCL-1, an intracellular target in cancer, by grafting the critical B-cell lymphoma 2 homology 3 helix of MCL-1 onto the Alphabody and tagging the scaffold's termini with designed cell-penetration polypeptides. Introduction of an albumin-binding moiety extended the serum half-life of the engineered Alphabody to therapeutically relevant levels, and administration thereof in mouse tumor xenografts based on myeloma cell lines reduced tumor burden. Crystal structures of such a designed Alphabody in complex with MCL-1 and serum albumin provided the structural blueprint of the applied design principles. Collectively, we provide proof of concept for the use of Alphabodies against intracellular disease mediators, which, to date, have remained in the realm of small-molecule therapeutics.

Structural basis for IL-12 and IL-23 receptor sharing reveals a gateway for shaping actions on T versus NK cells

Interleukin-12 (IL-12) and IL-23 are heterodimeric cytokines that are produced by antigen-presenting cells to regulate the activation and differentiation of lymphocytes, and they share IL-12Rβ1 as a receptor signaling subunit. We present a crystal structure of the quaternary IL-23 (IL-23p19/p40)/IL-23R/IL-12Rβ1 complex, together with cryoelectron microscopy (cryo-EM) maps of the complete IL-12 (IL-12p35/p40)/IL-12Rβ2/IL-12Rβ1 and IL-23 receptor (IL-23R) complexes, which reveal "non-canonical" topologies where IL-12Rβ1 directly engages the common p40 subunit. We targeted the shared IL-12Rβ1/p40 interface to design a panel of IL-12 partial agonists that preserved interferon gamma (IFNγ) induction by CD8+ T cells but impaired cytokine production from natural killer (NK) cells in vitro. These cell-biased properties were recapitulated in vivo, where IL-12 partial agonists elicited anti-tumor immunity to MC-38 murine adenocarcinoma absent the NK-cell-mediated toxicity seen with wild-type IL-12. Thus, the structural mechanism of receptor sharing used by IL-12 family cytokines provides a protein interface blueprint for tuning this cytokine axis for therapeutics.

Effect of interleukin-6, -17, -21, -22, and -23 and STAT3 on signal transduction pathways and their inhibition in autoimmune arthritis

Rheumatic diseases are complex autoimmune diseases which include among others rheumatoid arthritis (RA), juvenile idiopathic arthritis (JIA), and psoriatic arthritis (PsA). These diseases are characterized by prolonged and increased secretion of inflammatory factors, eventually leading to inflammation. This is often accompanied by persistent pain and stiffness in the joint and finally bone destruction and osteoporosis. These diseases can occur at any age, regardless of gender or origin. Autoimmune arthritis is admittedly associated with long-term treatment, and discontinuation of medication is associated with unavoidable relapse. Therefore, it is important to detect the disease at an early stage and apply appropriate preventative measures. During inflammation, pro-inflammatory factors such as interleukins (IL)-6, -17, -21, -22, and -23 are secreted, while anti-inflammatory factors including IL-10 are downregulated. Research conducted over the past several years has focused on inhibiting inflammatory pathways and activating anti-inflammatory factors to improve the quality of life of people with rheumatic diseases. The aim of this paper is to review current knowledge on stimulatory and inhibitory pathways involving the signal transducer and activator of transcription 3 (STAT3). STAT3 has been shown to be one of the crucial factors involved in inflammation and is directly linked with other pro-inflammatory factors and thus is a target of current research on rheumatoid diseases.

Axial spondyloarthritis: new advances in diagnosis and management

Axial spondyloarthritis (axSpA) is an inflammatory disease of the axial skeleton associated with significant pain and disability. Previously, the diagnosis of ankylosing spondylitis required advanced changes on plain radiographs of the sacroiliac joints. Classification criteria released in 2009, however, identified a subset of patients, under the age of 45, with back pain for more than three months in the absence of radiographic sacroiliitis who were classified as axSpA based on a positive magnetic resonance imaging or HLAB27 positivity and specific clinical features. This subgroup was labeled non-radiographic (nr)-axSpA. These patients, compared with those identified by the older New York criteria, contained a larger percentage of women and demonstrated less structural damage. However, their clinical manifestations and response to biologics were similar to radiographic axSpA. The discovery of the interleukin (IL) IL-23/IL-17 pathway revealed key molecules involved in the pathophysiology of axSpA. This discovery propelled the generation of antibodies directed toward IL-17A, which are highly effective and demonstrate treatment responses in axSpA that are similar to those observed with anti-TNF agents. The finding that agents that block IL-23 were not effective in axSpA came as a surprise and the potential underlying mechanisms underlying this lack of response are discussed. New agents with dual inhibition of the IL-17A and F isoforms and some oral small molecule agents that target the Jak-STAT pathway, have also shown efficacy in axSpA.

A non-clinical comparative study of IL-23 antibodies in psoriasis

Four antibodies that inhibit interleukin (IL)-23 are approved for the treatment of moderate-to-severe plaque psoriasis. Here, we present non-clinical data comparing ustekinumab, guselkumab, tildrakizumab and risankizumab with regard to thermostability, IL-23 binding affinity, inhibitory-binding mode, in vitro potency and in vivo efficacy. Risankizumab and guselkumab exhibited 5-fold higher affinity for IL-23 and showed more potent inhibition of IL-23 signaling than ustekinumab and tildrakizumab. Risankizumab and guselkumab completely blocked the binding of IL-23 to IL-23Rα as expected, whereas tildrakizumab did not. In vitro, risankizumab and guselkumab blocked the terminal differentiation of TH17 cells in a similar manner, while tildrakizumab had minimal impact on TH17 differentiation. In a human IL-23-induced ear-swelling mouse model, risankizumab and guselkumab were more effective than ustekinumab and tildrakizumab at reducing IL-17, IL-22, and keratinocyte gene expression. Our results indicate that the four clinically approved antibodies targeting IL-23 differ in affinity and binding epitope. These attributes contribute to differences in in vitro potency, receptor interaction inhibition mode and in vivo efficacy in preclinical studies as described in this report, and similarly may affect the clinical performance of these drugs.

The Association Study of IL-23R Polymorphisms With Cerebral Palsy in Chinese Population

Background: Cerebral palsy (CP) is a syndrome of non-progressive motor dysfunction caused by early brain development injury. Recent evidence has shown that immunological abnormalities are associated with an increased risk of CP.

Methods: We recruited 782 children with CP as the case group and 770 healthy children as the control group. The association between IL-23R single nucleotide polymorphisms (SNPs; namely, rs10889657, rs6682925, rs1884444, rs17375018, rs1004819, rs11805303, and rs10889677) and CP was studied by using a case–control method and SHEsis online software. Subgroup analysis based on complications and clinical subtypes was also carried out.

Results: There were differences in the allele and genotype frequencies between CP cases and controls at the rs11805303 and rs10889677 SNPs (Pallele = 0.014 and 0.048, respectively; Pgenotype = 0.023 and 0.008, respectively), and the difference in genotype frequency of rs10889677 remained significant after Bonferroni correction (Pgenotype = 0.048). Subgroup analysis revealed a more significant association of rs10889677 with CP accompanied by global developmental delay (Pgenotype = 0.024 after correction) and neonatal encephalopathy (Pgenotype = 0.024 after correction).

Conclusion: The present results showed a significant association between IL-23R and CP, suggesting that IL-23R may play a potential role in CP pathogenesis.

Homogeneously N-glycosylated proteins derived from the GlycoDelete HEK293 cell line enable diffraction-quality crystallogenesis

Structural studies of glycoproteins and their complexes provide critical insights into their roles in normal physiology and disease. Most glycoproteins contain N-linked glycosylation, a key post-translation modification that critically affects protein folding and stability and the binding kinetics underlying protein interactions. However, N-linked glycosylation is often an impediment to yielding homogeneous protein preparations for structure determination by X-ray crystallography or other methods. In particular, obtaining diffraction-quality crystals of such proteins and their complexes often requires modification of both the type of glycosylation patterns and their extent. Here, we demonstrate the benefits of producing target glycoproteins in the GlycoDelete human embryonic kidney 293 cell line that has been engineered to produce N-glycans as short glycan stumps comprising N-acetylglucosamine, galactose and sialic acid. Protein fragments of human Down syndrome cell-adhesion molecule and colony-stimulating factor 1 receptor were obtained from the GlycoDelete cell line for crystallization. The ensuing reduction in the extent and complexity of N-glycosylation in both protein molecules compared with alternative glycoengineering approaches enabled their productive deployment in structural studies by X-ray crystallography. Furthermore, a third successful implementation of the GlycoDelete technology focusing on murine IL-12B is shown to lead to N-glycosylation featuring an immature glycan in diffraction-quality crystals. It is proposed that the GlycoDelete cell line could serve as a valuable go-to option for the production of homogeneous glycoproteins and their complexes for structural studies by X-ray crystallography and cryo-electron microscopy.

All are Equal, Some are More Equal: Targeting IL 12 and 23 in IBD - A Clinical Perspective

Chronic inflammatory diseases like inflammatory bowel diseases (IBD) or psoriasis represents a worldwide health burden. Researchers provided great achievements in understanding the origin of these diseases leading to improved therapeutic options. The discovery of cytokines like tumor necrosis factor-α or transforming growth factor-β are examples for these efforts. Interleukin 12 (IL 12) and interleukin 23 (IL 23) represent different important cytokines in this regard. They both belong to the interleukin 12 family and are related by sharing the subunit p40. Ustekinumab is an antibody that blocks p40 and thereby interleukins 12 and 23. Trials showed promising results in treating IBD patients with this drug. Consequently, new questions arose about the distinct features of IL 12 and 23. This review focuses on these interleukins regarding their functions in the healthy and inflamed gut and provides an overview about the results from in vitro and in vivo studies as well as clinical trials.

Interleukin-23 drives expansion of Thelper 17 cells through epigenetic regulation by signal transducer and activators of transcription 3 in lupus patients

Objectives

To elucidate the molecular mechanisms underlying pathogenic Th17 cells, we investigated the modulation of epigenetic modifications and its association with SLE.

Methods

Naive CD4+ T cells were cultured in Th17 polarizing conditions for 5 days and then treated with various cytokines, including IL-23. Expression of Th17 cell–related markers and phosphorylation of signal transducers and activators of transcription (pSTATs) were analysed using flow cytometry and quantitative PCR. Histone modifications were assessed using chromatin immunoprecipitation PCR. T cell phenotypes and pSTATs were analysed in blood samples of patients with SLE (n = 28). Finally, the effects of baricitinib on memory Th17 cells were investigated in SLE patients (n = 12).

Results

Stimulation of resting Th17 cells with IL-23 promoted maturation of these cells (P &lt; 0.0001). IL-23 induced pSTAT3, but not pSTAT4, during Th17 cell maturation (P &lt; 0.05). IL-23-induced STAT3 directly bound the RORγT gene locus. This was accompanied by induction of the H3H4me3 permissive mark and reduction of the H3K27me3 repressive mark, leading to enhanced RORγT gene expression. IL-23-induced expansion of Th17 cells and pSTAT3 were suppressed by the addition of baricitinib in a concentration-dependent manner (P &lt; 0.05). In memory Th17 cells from SLE patients, pSTAT3 was hypersensitized by IL-23 stimulation and inhibited by baricitinib (P &lt; 0.05).

Conclusion

The results of this study indicate that IL-23/STAT3 signalling plays a fundamental role in Th17 cell maturation through transcriptional and epigenetic modifications in patients with SLE. This mechanism may underlie pathogenic Th17 cell expansion and may lead to identification of novel therapeutic targets for SLE.