Structures of the interleukin 11 signalling complex reveal gp130 dynamics and the inhibitory mechanism of a cytokine variant

Inhalable siRNA Targeting IL-11 Nanoparticles Significantly Inhibit Bleomycin-Induced Pulmonary Fibrosis

For idiopathic pulmonary fibrosis (IPF), interleukin 11 (IL-11) is a pivotal cytokine that stimulates the transformation of fibroblasts into myofibroblasts, thus accelerating the progression of pulmonary fibrosis. Here, we develop an innovative inhalable small interfering RNA (siRNA) delivery system termed PEI-GBZA, which demonstrates impressive efficiency in loading siIL-11 targeting IL-11 (siIL-11) and substantially suppresses the differentiation of fibroblasts into myofibroblasts and epithelial-mesenchymal transition (EMT), reduces neutrophil and macrophage recruitment, and ultimately relieves the established fibrotic lesions in the IPF model. PEI-GBZA is prepared by modifying low-molecular-weight polyethylenimine (PEI) with 4-guanidinobenzoic acid (GBZA). The resulting PEI-GBZA may effectively encapsulate siIL-11 through a variety of interactions such as hydrophobic, hydrogen bonding, and electrostatic interactions, creating stable carrier/siIL-11 nanoparticles (PEI-GBZA/siIL-11 NPs). Upon inhalation, PEI-GBZA/siIL-11 NPs demonstrate effective retention in fibrotic lesions, leading to a marked mitigation of disease progression in a bleomycin-induced pulmonary fibrosis model. Impressively, this inhalation therapy exhibits negligible systemic toxicity. This work provides a universal and noninvasive RNA therapeutic delivery platform that holds significant promise for respiratory diseases. The potential for clinical application of this platform is substantial, offering a frontier for the treatment of IPF and potentially other pulmonary disorders.

Site-specific dimerization of interleukin-11 alleviates bleomycin-induced pulmonary fibrosis in mice

Interleukin-11 (IL-11) has recently been identified as a critical profibrotic cytokine, and IL-11 signaling pathway via IL-11Rα and GP130 receptors has been shown to be a promising therapeutic target for the treatment of fibrotic diseases. Herein, we devised two kinds of IL-11 dimer with receptor-biased binding ability through site-specific crosslinking at the interface involving GP130 binding and signaling, aiming to explore their therapeutic potentials for bleomycin-induced pulmonary fibrosis in mice. A single cysteine mutation at site W147 of human IL-11 (IL-11 W147C) was conducted for site-specific crosslinking. The ability of GP130 to bind to IL-11 W147C dimer was substantially weakened by cysteine-based dimerization, while the ability of IL-11 W147C dimer to bind to IL-11Rα was almost entirely preserved or even enhanced. The IL-11 W147C dimer potently inhibited TF-1 cell proliferation and TGF-β1-induced human lung fibroblast differentiation into myofibroblasts. We also showed that dimerization substantially extended the circulation time of IL-11 W147C dimer in healthy rats. Subcutaneous administration of IL-11 W147C dimer significantly reduced extracellular matrix deposition, preserved alveolar architecture and alleviated pulmonary fibrosis development in mice. The findings of this study may provide a general strategy for the design of cytokine-based receptor-biased antagonists and agonists targeting these multifaceted signaling pathways.

Blocking GP130 binding in interleukin-11 through site-specific PEGylation attenuates bleomycin-induced pulmonary fibrosis in mice

Recent insights have identified interleukin-11 (IL-11) as a pivotal profibrotic cytokine, with its signaling through IL-11Rα and GP130 receptors emerging as a promising therapeutic target for fibrotic diseases. Herein, we developed receptor-biased IL-11 via site-specific PEGylation at the GP130 binding interface, aiming to explore its therapeutic potential for bleomycin-induced pulmonary fibrosis in mice. By conducting single site-directed cysteine mutagenesis at site II or site III of IL-11, we refined the conjugation site, demonstrating that mutation at site III exhibits heightened sensitivity to GP130 binding and signaling. Cysteine-based PEGylation substantially attenuated the ability of GP130 to bind to IL-11 W147C, while almost entirely preserving its IL-11Rα binding ability. These PEGylated IL-11 W147C analogs showed potent inhibition of TF-1 cell proliferation and significant antagonism to TGF-β1-induced human lung fibroblasts (HLFs) differentiation into myofibroblasts. Moreover, PEGylation significantly prolonged the half-life of IL-11 W147C in healthy rats. Subcutaneous administration of PEGylated analogs, particularly PEG20/40 k-IL-11 W147C, effectively mitigated extracellular matrix deposition, preserved alveolar architecture, and attenuated the progression of pulmonary fibrosis in mice. The finding of this study not only underscores the therapeutic potential of IL-11 modulation, but also provides a general strategy for the design of cytokine-based biased antagonists and agonists targeting these multifaceted signaling pathways.

De novo discovery of cyclic peptide inhibitors of IL-11 signaling

Interleukin-11 (IL-11), a member of the IL-6 cytokine family, has potential pro-inflammatory and pro-fibrotic roles in pulmonary, hepatic, cardiovascular, renal and intestinal disease pathogenesis, including oncogenesis. The potential for therapeutic intervention in these disease spaces has therefore made the IL-11 signaling axis an attractive target in drug discovery, and antibody inhibitors of IL-11 signaling are currently under evaluation in Phase I/II clinical trials. While lower molecular weight small molecule and peptide inhibitors may offer the potential for improved tissue penetration, developability and manufacturing cost compared with a protein therapeutic, reports of such chemical matter in the literature are limited. In this work, a series of cyclic peptides derived from phage display biopanning campaigns against both IL-11 and its cognate receptor IL-11Rα are presented. The most active IL-11 binder (peptide 4, KD 140 nM) exhibited inhibition of IL-11/IL-11Rα dimerization in a biochemical AlphaLISA assay (Ki 300 nM), and alanine scanning was carried out on this sequence to identify residues important for target binding and inhibitory activity. Further structural optimization yielded lead peptide 15 (Ki 180 nM), which exhibited at least 70-fold greater activity than IL-11 inhibitors previously reported in the literature. The de novo peptide macrocycles presented serve as a robust starting point for development of therapeutic inhibitors of the IL-11/IL-11Rα interaction.

Structures of complete extracellular assemblies of type I and type II Oncostatin M receptor complexes

Oncostatin M (OSM) is a unique Interleukin 6 (IL-6) family cytokine that plays pivotal roles in numerous biological events by signaling via two types of receptor complexes. While type I OSM receptor complex is formed by glycoprotein 130 (gp130) heterodimerization with Leukemia Inhibitory Factor receptor (LIFR), type II OSM receptor complex is composed of gp130 and OSM receptor (OSMR). OSM is an important contributor to multiple inflammatory diseases and cancers while OSM inhibition has been shown to be effective at reducing symptoms, making OSM an attractive therapeutic target. Using cryogenic electron microscopy (cryo-EM), we characterize full extracellular assemblies of human type I OSM receptor complex and mouse type II OSM receptor complex. The juxtamembrane domains of both complexes are situated in close proximity due to acute bends of the receptors. The rigid N-terminal extension of OSM contributes to gp130 binding and OSM signaling. Neither glycosylation nor pro-domain cleavage of OSM affects its activity. Mutagenesis identifies multiple OSM and OSMR residues crucial for complex formation and signaling. Our data reveal the structural basis for the assemblies of both type I and type II OSM receptor complexes and provide insights for modulation of OSM signaling in therapeutics.

The structure of the IL-11 signalling complex provides insight into receptor variants associated with craniosynostosis

Interleukin 11 (IL-11), a member of the IL-6 family of cytokines, has roles in haematopoiesis, inflammation, bone metabolism, and craniofacial development. IL-11 also has pathological roles in chronic inflammatory diseases, fibrosis, and cancer. In this structural snapshot, we explore our recently published cryo-EM structure of the human IL-11 signalling complex to understand the molecular mechanisms of complex formation and disease-associated mutations. IL-11 signals by binding to its cell surface receptors, the IL-11 receptor α subunit (IL-11Rα) and glycoprotein 130 (gp130), to form a hexameric signalling complex. We examine the locations within the complex of receptor sequence variants that are associated with craniosynostosis and craniosynostosis-like phenotypes and speculate on potential molecular mechanisms leading to defects in signalling function. While these causative amino acid sequence changes in IL-11Rα are generally distal to interfaces between components of the complex, important structural residues are highly represented, including proline residues, cysteine residues involved in disulfide bonds, and residues within or surrounding the tryptophan-arginine ladder. We also note the locations and potential effects of amino acid substitutions within the extracellular domains of gp130 that are associated with craniosynostosis. As focus on the physiological and pathological functions of IL-11 grows, the importance of high-resolution structural knowledge of IL-11 signalling to understand disease-associated mutations and to inform therapeutic strategies will only increase.

The JAK-STAT pathway: from structural biology to cytokine engineering

The Janus kinase-signal transducer and activator of transcription (JAK-STAT) pathway serves as a paradigm for signal transduction from the extracellular environment to the nucleus. It plays a pivotal role in physiological functions, such as hematopoiesis, immune balance, tissue homeostasis, and surveillance against tumors. Dysregulation of this pathway may lead to various disease conditions such as immune deficiencies, autoimmune diseases, hematologic disorders, and cancer. Due to its critical role in maintaining human health and involvement in disease, extensive studies have been conducted on this pathway, ranging from basic research to medical applications. Advances in the structural biology of this pathway have enabled us to gain insights into how the signaling cascade operates at the molecular level, laying the groundwork for therapeutic development targeting this pathway. Various strategies have been developed to restore its normal function, with promising therapeutic potential. Enhanced comprehension of these molecular mechanisms, combined with advances in protein engineering methodologies, has allowed us to engineer cytokines with tailored properties for targeted therapeutic applications, thereby enhancing their efficiency and safety. In this review, we outline the structural basis that governs key nodes in this pathway, offering a comprehensive overview of the signal transduction process. Furthermore, we explore recent advances in cytokine engineering for therapeutic development in this pathway.

Enhancing antitumor immunity and achieving tumor eradication with IL11RA mRNA immunotherapy

Current methods for delivering genes to target tumors face significant challenges, including off-target effects and immune responses against delivery vectors. In this study, we developed a novel approach using messenger RNA (mRNA) to encode IL11RA for local immunotherapy, aiming to harness the immune system to combat tumors. Our research uncovered a compelling correlation between IL11RA expression and CD8 + T cell levels across multiple tumor types, with elevated IL11RA expression correlating with improved overall survival. Examination of the Pan-Cancer Atlas dataset showed a significant reduction in IL11RA expression in various cancer types compared to normal tissue, raising questions about its potential role in tumorigenesis. To achieve efficient in vivo expression of IL11RA, we synthesized two mRNA sequences mimicking the wild-type protein. These mRNA sequences were formulated and capped to ensure effective delivery, resulting in robust expression within tumor sites. Our investigation into IL11RA mRNA therapy demonstrated its effectiveness in controlling tumor growth when administered both intratumorally and intravenously in mouse models. Additionally, IL11RA mRNA treatment significantly stimulated the expansion of CD8 + T cells within tumors, draining lymph nodes, and the spleen. Transcriptome analysis revealed distinct transcriptional patterns associated with T cell functions. Using multiple deconvolution algorithms, we found substantial infiltration of CD8 + T cells following IL11RA mRNA treatment, highlighting its immunomodulatory effects within the tumor microenvironment. In conclusion, IL11RA mRNA therapy presents a promising strategy for tumor regression with potential immunomodulatory effects and clinical implications for improved survival outcomes.

Craniosynostosis-associated variants in the IL-11R complex: new insights and questions

Skull growth involves the expansion of both the flat calvarial bones of the skull and the fibrous marginal zones, termed sutures, between them. This process depends on co-ordinated proliferation of mesenchymal-derived progenitor cells within the sutures, and their differentiation to osteoblasts which produce the bone matrix required to expand the size of the bony plates. Defects lead to premature closure of these sutures, termed craniosynostosis, resulting in heterogeneous head shape differences due to restricted growth of one or more sutures. The impact on the individual depends on how many and which sutures are affected and the severity of the effect. Several genetic loci are responsible, including a wide range of variants in the gene for the interleukin 11 receptor (IL11RA, OMIM#600939). Recent work from Kespohl and colleagues provides new insights into how some of these variants influence IL-11R function; we discuss their influences on IL-11R structure and IL-11 function as a stimulus of osteoblast differentiation.

Structural insights into IL-11-mediated signalling and human IL6ST variant-associated immunodeficiency

IL-11 and IL-6 activate signalling via assembly of the cell surface receptor gp130; however, it is unclear how signals are transmitted across the membrane to instruct cellular responses. Here we solve the cryoEM structure of the IL-11 receptor recognition complex to discover how differences in gp130-binding interfaces may drive signalling outcomes. We explore how mutations in the IL6ST gene encoding for gp130, which cause severe immune deficiencies in humans, impair signalling without blocking cytokine binding. We use cryoEM to solve structures of both IL-11 and IL-6 complexes with a mutant form of gp130 associated with human disease. Together with molecular dynamics simulations, we show that the disease-associated variant led to an increase in flexibility including motion within the cytokine-binding core and increased distance between extracellular domains. However, these distances are minimized as the transmembrane helix exits the membrane, suggesting a stringency in geometry for signalling and dimmer switch mode of action.