Safety and efficacy of eblasakimab, an interleukin 13 receptor α1 monoclonal antibody, in adults with moderate-to-severe atopic dermatitis: A phase 1b, multiple-ascending dose study.

BACKGROUND: Eblasakimab, an interleukin (IL)-13 receptor α1 antagonist, blocks IL-4 and IL-13 signaling through the type 2 receptor. OBJECTIVE: The safety and efficacy of eblasakimab was evaluated in adults with moderate-to-severe atopic dermatitis (AD). METHODS: In this phase 1b randomized, double-blinded study, 52 patients with moderate-to-severe AD received weekly subcutaneous injections of eblasakimab 200, 400, or 600 mg, or placebo for 8 weeks. Primary outcome was the incidence of treatment-emergent adverse events. Secondary outcomes included percentage change in the Eczema Area and Severity Index from baseline; Eczema Area and Severity Index improvement of at least 50%, 75%, or 90% from baseline; and percentage change in the peak-pruritus numeric rating scale score from baseline. RESULTS: Treatment-emergent adverse events were reported in 47% placebo and 71% eblasakimab patients; most were considered mild or moderate and did not lead to study discontinuation. At week 8 eblasakimab 600 mg showed statistically significant improvement in mean percentage change in Eczema Area and Severity Index versus placebo (-65% vs -27%, P = .014). Other key secondary physician- and patient-reported end points were met. LIMITATIONS: Longer studies are required to confirm eblasakimab safety and efficacy in AD patients. CONCLUSIONS: Treatment of adults with moderate-to-severe AD with eblasakimab was well-tolerated and associated with significant clinical improvements versus placebo.

IL-13 promotes functional recovery after myocardial infarction via direct signaling to macrophages.

There is great interest in identifying signaling pathways that promote cardiac repair after myocardial infarction (MI). Prior studies suggest a beneficial role for IL-13 signaling in neonatal heart regeneration; however, the cell types mediating cardiac regeneration and the extent of IL-13 signaling in the adult heart after injury are unknown. We identified an abundant source of IL-13 and the related cytokine, IL-4, in neonatal cardiac type 2 innate lymphoid cells, but this phenomenon declined precipitously in adult hearts. Moreover, IL-13 receptor deletion in macrophages impaired cardiac function and resulted in larger scars early after neonatal MI. By using a combination of recombinant IL-13 administration and cell-specific IL-13 receptor genetic deletion models, we found that IL-13 signaling specifically to macrophages mediated cardiac functional recovery after MI in adult mice. Single transcriptomics revealed a subpopulation of cardiac macrophages in response to IL-13 administration. These IL-13-induced macrophages were highly efferocytotic and were identified by high IL-1R2 expression. Collectively, we elucidated a strongly proreparative role for IL-13 signaling directly to macrophages following cardiac injury. While this pathway is active in proregenerative neonatal stages, reactivation of macrophage IL-13 signaling is required to promote cardiac functional recovery in adults.

Eblasakimab, a novel IL-13 receptor alpha 1 monoclonal antibody, blocks STAT6 phosphorylation with low dose in human volunteers.

Eblasakimab is a first-in-class monoclonal antibody under investigation for the treatment of atopic dermatitis (AD), which targets IL-13Rα1, a subunit of the Type 2 receptor complex. IL-13Rα1 stimulates phosphorylation of signal transducer and activator of transcription 6 (STAT6) to drive inflammation. This brief report investigates the mechanistic basis of eblasakimab and its effects on IL-13Rα1 signaling as part of a phase 1a, open-label, single ascending dose study. Single ascending doses of eblasakimab were administered by intravenous or subcutaneous injection to healthy male volunteers. The impact of eblasakimab on IL-13Rα1 receptor occupancy and STAT6 phosphorylation was assessed in participant blood monocytes. No serious treatment emergent adverse events were reported. Eblasakimab effectively blocked the IL-13Rα1 receptor and inhibited STAT6 phosphorylation with single doses of 3 mg/kg intravenously and 300 mg subcutaneously. Results support further clinical development of eblasakimab as a novel biologic for AD, with potential for 2- to 4-week dosing regimens.

Interleukin-13 reduces bone erosion in rheumatoid arthritis by up-regulating osteoprotegerin expression in fibroblast-like synoviocytes : an in vitro and in vivo study.

OBJECTIVES: Bone erosion in rheumatoid arthritis (RA) is partly caused by excessive activation of osteoclasts. Osteoclasts can be derived from RA synovium and their differentiation can be inhibited by osteoprotegerin (OPG), a decoy receptor of the osteoclastogenesis-promoting cytokine receptor activator of nuclear factor κB ligand (RANKL). Fibroblast-like synoviocytes (FLSs) are the main stromal cells in the synovium that can secret OPG. The OPG secretion of FLSs can be modulated by various cytokines. Interleukin (IL)-13 can alleviate bone erosion in RA mouse models, but the mechanisms remain unclear. Therefore, we aimed to investigate whether IL-13 can induce OPG secretion by RA-FLSs, thus ameliorating bone destruction in RA by inhibiting osteoclast differentiation. METHODS: OPG, RANKL, and IL-13 receptors expression by RA-FLSs were evaluated by RT-qPCR. OPG secretion was determined by ELISA. Western blot was performed to analyse OPG expression and the activation of the STAT6 pathway. IL-13 and (or) OPG siRNA pre-treated RA-FLSs conditioned medium were used in osteoclast induction to test if IL-13 can inhibit osteoclastogenesis by up-regulating OPG in RA-FLSs. Micro-CT and immunofluorescence were performed to determine if IL-13 can induce OPG expression and alleviate bone erosion in vivo. RESULTS: IL-13 can promote OPG expression of RA-FLSs, and the promotion can be overcome by IL-13Rα1 or IL-13Rα2 siRNA transfection, or STAT6 inhibitor. Osteoclast differentiation can be inhibited by IL-13 pre-treated RA-FLSs conditioned medium. The inhibition can be reversed by OPG siRNA transfection. IL-13 injection can increase OPG expression in the joints while reducing bone destruction in collagen-induced arthritis mice. CONCLUSIONS: IL-13 can inhibit osteoclastogenesis by up-regulating OPG in RA-FLSs through IL-13 receptors via the STAT6 pathway, thus may ameliorate bone erosion in RA.

Interleukin-3 stabilizes CD124/IL-4α surface expression in mast cells via Tyk2 and STAT6.

Interleukin (IL)-4 signals can modulate mast cells, which express the IL-4Rα chain. The IL-4Rα can heterodimerise with the common γ-chain and utilizes JAK1 and JAK2 for signal transduction, while complexes of IL-4Rα with IL-13Rα1 subunit mediates signals via JAK2 and Tyk2. Here, we report that IL-3 is an essential factor for the continuous expression of the IL-4Rα chain on mast cells, which did not express the IL-13Rα1 chain. We demonstrate that the signals induced by IL-3 important for IL-4Rα expression are mediated by Tyk2 and STAT6 activation and the subsequent maintenance of HSP90 levels. In line with that, inhibition of either Tyk2, STAT6 or HSP90 impaired the IL-3-induced IL-4Rα upregulation. Consequently, the IL-3 maintained IL-4Rα surface expression via Tyk2 is essential for the costimulatory effect of IL-4 on the IL-33-induced production of IL-6 and IL-13.

Increased Expression of Interleukin-13 Receptor in Ileum Associated With Nonresponse to Adalimumab in Ileal Crohn's Disease.

BACKGROUND: The terminal ileum poses a predilection for Crohn's disease (CD) but is less susceptible to undergo healing to treatment with biologics and small molecules. This study aimed to evaluate histologic features associated with endoscopic remission (ER). METHODS: This is a post hoc analysis of patients with moderately to severely active CD, defined as Crohn's disease activity index 220 to 450, and terminal ileal ulceration treated with antitumor necrosis factor (TNF)-α inhibitor adalimumab from the EXTEND trial. We studied whether baseline total Global Histologic Disease Activity Scores (GHAS), any individual histologic element, and specific immunohistochemical (IHC) markers of chronic inflammation from biopsy specimens were associated with postinduction (week 12) and maintenance (week 52) ER, defined as Simple Endoscopic Score for Crohn's Disease of 0. Multivariable logistic regression models adjusted for confounders were used to assess the relationship between histologic markers and 1-year outcomes. RESULTS: Seventy-one adult patients with CD affecting the ileum were included in this analysis. Both baseline ileal GHAS scores and individual histologic components were not found to be associated with ER at weeks 12 or 52. Increased expression of interleukin-13 receptor (IL-13R) on IHC stains was associated with reduced likelihood of achieving 1-year ER (adjusted odds ratio, 0.06; 95% CI, 0.01-0.92; P = .044). No other biomarker assessed was associated with 1-year ER. CONCLUSIONS: Ileal histologic disease activity and IHC activation markers of chronic mucosal inflammation were not associated with 1-year ER. However, strong staining for IL-13 receptor in the ileum was associated with reduced odds of 1-year ER using adalimumab. Mucosal cellular disease profiles might pose an opportunity to guide treatment of CD.

In this post hoc analysis, ileal histologic disease activity and IHC activation markers of chronic mucosal inflammation were not predictive of 1-year ER. However, strong staining for IL-13R in the ileum was associated with reduced odds of 1-year ER using adalimumab.

Spotlight on a Short-Time Treatment with the IL-4/IL-13 Receptor Blocker in Patients with CRSwNP: microRNAs Modulations and Preliminary Clinical Evidence.

Already used for the treatment of some allergic and inflammatory diseases, such as asthma or atopic dermatitis, dupilumab has also been approved as add-on therapy for patients with CRSwNP, and it could represent the keystone to reducing the remission time as well as to improve healing and quality of life. On the other hand, the role of miRNAs as potential biomarkers of immune modulation is emerging. We analyzed the effects of a short-time treatment with dupilumab in patients with CRSwNP, analyzing the immune response modification as well as miRNAs modulations. First, in this early observation stage, all patients experienced remarkable improvement and were clinically stable. Indeed, we observed a significant decrease in CD4+ T cells and a significant reduction in total IgE (p < 0.05) and serum IL-8 levels (p < 0.01), indicating a reduction in the general inflammatory condition. In addition, we analyzed a panel of about 200 circulating miRNAs. After treatment, we noted a significant downregulation of hsa-mir-25-3p (p-value = 0.02415) and hsa-mir-185-5p (p-value = 0.04547), two miRNAs involved in the proliferation, inflammation, and dug-resistance, in accordance with the clinical status of patients. All these preliminary data aimed to identify new biomarkers of prognosis, identifiable with non-invasive procedures for patients. Further, these patients are still under observation, and others with different levels of responsiveness to treatment need to be enrolled to increase the statistical data.

Liver group 2 innate lymphoid cells regulate blood glucose levels through IL-13 signaling and suppression of gluconeogenesis.

The liver stores glycogen and releases glucose into the blood upon increased energy demand. Group 2 innate lymphoid cells (ILC2) in adipose and pancreatic tissues are known for their involvement in glucose homeostasis, but the metabolic contribution of liver ILC2s has not been studied in detail. Here we show that liver ILC2s are directly involved in the regulation of blood glucose levels. Mechanistically, interleukin (IL)-33 treatment induces IL-13 production in liver ILC2s, while directly suppressing gluconeogenesis in a specific Hnf4a/G6pc-high primary hepatocyte cluster via Stat3. These hepatocytes significantly interact with liver ILC2s via IL-13/IL-13 receptor signaling. The results of transcriptional complex analysis and GATA3-ChIP-seq, ATAC-seq, and scRNA-seq trajectory analyses establish a positive regulatory role for the transcription factor GATA3 in IL-13 production by liver ILC2s, while AP-1 family members are shown to suppress IL-13 release. Thus, we identify a regulatory role and molecular mechanism by which liver ILC2s contribute to glucose homeostasis.

Interleukin-13 Receptor α1-Mediated Signaling Regulates Age-Associated/Autoimmune B Cell Expansion and Lupus Pathogenesis.

OBJECTIVE: Age-associated/autoimmune B cells (ABCs) are an emerging B cell subset with aberrant expansion in systemic lupus erythematosus. ABC generation and differentiation exhibit marked sexual dimorphism, and Toll-like receptor 7 (TLR-7) engagement is a key contributor to these sex differences. ABC generation is also controlled by interleukin-21 (IL-21) and its interplay with interferon-γ and IL-4. This study was undertaken to investigate whether IL-13 receptor α1 (IL-13Rα1), an X-linked receptor that transmits IL-4/IL-13 signals, regulates ABCs and lupus pathogenesis. METHODS: Mice lacking DEF-6 and switch-associated protein 70 (double-knockout [DKO]), which preferentially develop lupus in females, were crossed with IL-13Rα1-knockout mice. IL-13Rα1-knockout male mice were also crossed with Y chromosome autoimmune accelerator (Yaa) DKO mice, which overexpress TLR-7 and develop severe disease. ABCs were assessed using flow cytometry and RNA-Seq. Lupus pathogenesis was evaluated using serologic and histologic analyses. RESULTS: ABCs expressed higher levels of IL-13Rα1 than follicular B cells. The absence of IL-13Rα1 in either DKO female mice or Yaa DKO male mice decreased the accumulation of ABCs, the differentiation of ABCs into plasmablasts, and autoantibody production. Lack of IL-13Rα1 also prolonged survival and delayed the development of tissue inflammation. IL-13Rα1 deficiency diminished in vitro generation of ABCs, an effect that, surprisingly, could be observed in response to IL-21 alone. RNA-Seq revealed that ABCs lacking IL-13Rα1 down-regulated some histologic characteristics of B cells but up-regulated myeloid markers and proinflammatory mediators. CONCLUSION: Our findings indicate a novel role for IL-13Rα1 in controlling ABC generation and differentiation, suggesting that IL-13Rα1 contributes to these effects by regulating a subset of IL-21-mediated signaling events. These results also suggest that X-linked genes besides TLR7 participate in the regulation of ABCs in lupus.

T Helper 2 IL-4/IL-13 Dual Blockade with Dupilumab Is Linked to Some Emergent T Helper 17‒Type Diseases, Including Seronegative Arthritis and Enthesitis/Enthesopathy, but Not to Humoral Autoimmune Diseases.

Dupilumab, an IL-4/IL-13 receptor blocker, has been linked to emergent seronegative inflammatory arthritis and psoriasis that form part of the spondyloarthropathy spectrum. We systematically investigated patterns of immune disorders, including predominantly T helper 17‒(spondyloarthropathy pattern) and T helper 2‒mediated disorders and humoral autoimmune pattern diseases, using VigiBase, the World Health Organization's global pharmacovigilance of adverse drug reactions. Several bioinformatics databases and repositories were mined to couple dupilumab-related immunopharmacovigilance with molecular cascades relevant to reported findings. A total of 37,848 dupilumab adverse drug reaction cases were reported, with skin, eye, and musculoskeletal systems most affected. Seronegative arthritis (OR = 9.61), psoriasis (OR = 1.48), enthesitis/enthesopathy (OR = 12.65), and iridocyclitis (OR = 3.77) were highly associated. However, ankylosing spondylitis and inflammatory bowel disease were not conclusively associated. Overall, classic polygenic humoral‒mediated autoimmune diseases such as rheumatoid arthritis and systemic lupus erythematosus were not associated with dupilumab use. Pathway analysis identified several biological pathways potentially involved in dupilumab‒associated adverse drug reactions, including the fibroblast GF receptor (in particular, FGFR2) pathway. MicroRNAs analysis revealed the potential involvement of hsa-miR-21-5p and hsa-miR-335-5p. In conclusion, IL-4/IL-13 blockers are not unexpectedly protective against humoral autoimmune diseases but dynamically skew immune responses toward some IL-23/IL-17 cytokine pathway‒related diseases. IL-4/13 axis also plays a role in homeostatic tissue repair and we noted evidence for a link with ocular and arterial pathology.

99mTc-labeled peptide targeting interleukin 13 receptor α 2 for tumor imaging in a cervical cancer mouse model.

OBJECTIVE: Pep-1 (CGEMGWVRC) can potently bind to interleukin 13 receptor α 2 (IL-13Rα2), a tumor-restricted receptor found to be expressed in various malignancies. In this study, we intended to prepare a 99mTc-labeled probe and evaluate its in vivo tumor accumulation properties in a cervical cancer xenograft model. METHODS: The Pep-1 was designed and radiolabeled with 99mTc by conjugation with mercaptoacetyl-triglycine (MAG3). The labeling yield, radiochemical purity and stability were characterized in vitro. Cell uptake assays and fluorescence imaging were conducted for qualitative and quantitative evaluation of the specificity and affinity of Pep-1. Flow cytometry and tissue immunofluorescence were used to confirm the IL-13Rα2 expression in cervical cancer. Biodistribution and in vivo imaging were performed periodically to evaluate the imaging value of 99mTc-MAG3-Pep-1 in cervical cancer xenograft model. RESULTS: 99mTc-MAG3-Pep-1 was successfully prepared with a high labeling yield and radiochemical purity (> 95%). Specific cell uptake was demonstrated by scramble control and unlabeled MAG3-Pep-1 blockade. Flow cytometry and tissue immunofluorescence also confirmed the mild IL-13Rα2 expression of HeLa. In the gamma imaging study and biodistribution, the tumors were imaged clearly at 2-6 h after injection of 99mTc-MAG3-Pep-1 and the accumulation of 99mTc-MAG3-Pep-1 in tumor was significantly higher than that in the blocking and scramble controls, demonstrating ligand-receptor binding specificity. CONCLUSIONS: This work demonstrated that 99mTc-MAG3-Pep-1 can bind to cervical cancer with high affinity and specificity. MAG3-Pep-1 may be a prospective precursor for IL-13Rα2-expressing cancer therapy.

Molecular characterization, expression analysis and cellular location of IL-4/13 receptors in large yellow croaker (Larimichthys crocea).

Interleukin (IL)-4 and IL-13 are closely related class I cytokines that play key roles in the T helper (Th)-2 immune response via heterodimeric receptors. IL-4 signals via both the type I (IL-4Rα/γc) and type II (IL-4Rα/IL-13Rα1) receptor complexes, while IL-13 signals only via the type II receptor complex. IL-13Rα2 is traditionally considered a "decoy" receptor for IL-13. However, the IL-4/13 system and its response to pathogenic infection are still not fully understood in fish. In this study, we identified four IL-4/13 receptor subunit genes in the large yellow croaker (Larimichthys crocea): LcIL-4Rα1, LcIL-4Rα2, LcIL-13Rα1, and LcIL-13Rα2. Sequence analysis showed that these receptors possessed typical characteristic domains, including a signal peptide, two fibronectin type III (FN III)-like domains, and a transmembrane domain, but their cytoplasmic regions were not well conserved. The mRNA and protein of the four IL-4/13 receptors were constitutively expressed in all examined tissues of large yellow croaker. Their mRNAs were also detected in primary head kidney macrophages (PKMs), primary head kidney granulocytes (PKGs), and primary head kidney lymphocytes (PKLs). Immunofluorescence assay further showed that LcIL-4Rα and LcIL-13Rα1 were expressed on the membrane of IgM + B cells. After stimulation by Vibrio alginolyticus and poly (I:C) (a viral dsRNA mimic), the mRNA levels of LcIL-4/13 receptors were significantly upregulated in the head kidney and spleen. Their mRNA levels were also upregulated in head kidney leukocytes in response to poly (I:C) and lipopolysaccharide (LPS) treatment. Moreover, both recombinant LcIL-4/13A and LcIL-4/13B upregulated LcIL-4Rα1 and LcIL-4Rα2 in primary leukocytes, but only recombinant LcIL-4/13A upregulated LcIL-13Rα1 and LcIL-13Rα2. These results indicated that LcIL-4/13 receptors, containing conserved functional domains, may be involved in the IL-4/13-mediated immune response to pathogenic infections in the large yellow croaker.

Innate immune regulates cutaneous sensory IL-13 receptor alpha 2 to promote atopic dermatitis.

The clinical significance and regulators of IL-13Rα2 in itch and atopic dermatitis (AD) remain unclear. To identify disease-driven regulatory circuits of IL-13Rα2, transcriptomic/pathological analysis was performed in skin from patients with AD, psoriasis, healthy subjects, and murine AD model. Functionality was investigated in sensory neurons, keratinocytes and animal model, by using knockdown (KD), calcium imaging, RNA-seq, cytokine arrays, pharmacological assays, and behavioural investigations. In our study, an upregulated IL-13Rα2 expression was revealed in skin of AD patients, but not psoriasis, in a disease activity-dependent manner. In cultured human keratinocytes, IL-13 increased IL-13Rα2 transcription levels, and this were downregulated by IL-13Rα1KD. IL-13Rα2KD reduced transcription levels of EDNRA, CCL20, CCL26. In contrast, sensory neuron-derived IL-13Rα2 was upregulated by TLR2 heterodimer agonists, Pam3CSK4 and FSL-1. In a mouse cheek model, pre-administration of Pam3CSK4 and FSL-1 enhanced IL-13-elicited scratching behaviour. Consistently, in cultured sensory neurons Pam3CSK4 enhanced IL-13-elicted calcium transients, increased number of responders, and orchestrated chemerin, CCL17 and CCL22 release. These release was inhibited by IL-13Rα2KD. Collectively, IL-13 regulates keratinocyte-derived IL-13Rα2 and TLR2 to modulate neuronal IL-13Rα2, thereby promoting neurogenic inflammation and exacerbating AD and itch. Thus, the cutaneous IL-13-IL-13Rα2 and neuronal TLR2-IL-13Rα2 pathway represent important targets to treat AD and itch.

Possible Roles of Interleukin-4 and -13 and Their Receptors in Gastric and Colon Cancer.

Interleukin (IL)-4 and -13 are structurally and functionally related cytokines sharing common receptor subunits. They regulate immune responses and, moreover, are involved in the pathogenesis of a variety of human neoplasms. Three different receptors have been described for IL-4, but only IL-4 receptor type II (IL-4Rα/IL-13Rα1) is expressed in solid tumors. While IL-13 can also bind to three different receptors, IL-13 receptor type I (IL-4Rα/IL-13Rα1/IL-13Rα2) and type II (IL-4Rα/IL-13Rα1) are expressed in solid tumors. After receptor binding, IL-4 and IL-13 can mediate tumor cell proliferation, survival, and metastasis in gastric or colon cancer. This review summarizes the results about the role of IL-4/IL-13 and their receptors in gastric and colon cancer.

Dupilumab improves upper and lower airway disease control in chronic rhinosinusitis with nasal polyps and asthma.

BACKGROUND: Chronic rhinosinusitis with nasal polyps (CRSwNP) and type 2 asthma share the same inflammatory pathophysiology and are frequent comorbidities. Dupilumab, a fully human monoclonal antibody, blocks the shared receptor component for interleukin 4 and interleukin 13, which are key and central drivers of type 2 inflammation. OBJECTIVE: We report the effect of dupilumab vs placebo on outcome measures of the upper and lower airways and health-related quality of life (HRQoL) in the pooled population of patients with CRSwNP and comorbid asthma from the phase 3 SINUS-24 (NCT02912468) and SINUS-52 (NCT02898454) studies. METHODS: In these randomized, double-blind, placebo-controlled trials, patients received subcutaneous dupilumab 300 mg (n = 438) or placebo (n = 286) every 2 weeks on a background of mometasone furoate nasal spray. Changes from baseline at week 24 in the upper and lower airway outcome measures are reported. RESULTS: Of the 724 patients randomized, 428 (59.1%) had comorbid asthma. In patients with asthma at week 24, dupilumab vs placebo improved the nasal polyp score (-2.04), patient-reported nasal congestion score (-1.04), Lund-Mackay computed tomography scan score (-6.43), peak nasal inspiratory flow (46.15 L/min), and 22-item sinonasal outcome test score (-21.42; all P < .001). The forced expiratory volume in 1 second and 6-item asthma control questionnaire scores were also markedly improved with dupilumab vs placebo. The most common adverse events (nasopharyngitis, headache, injection-site erythema, worsening of nasal polyposis, and asthma) were more frequent with placebo than dupilumab. CONCLUSION: Dupilumab improved upper and lower airway outcome measures and HRQoL in patients with severe CRSwNP and comorbid asthma and was well tolerated. TRIAL REGISTRATION: ClinicalTrials.gov Identifiers: NCT02912468 (SINUS-24) and NCT02898454 (SINUS-52).

IL-13 antagonists in the treatment of atopic dermatitis.

Atopic dermatitis (AD) is a prevalent inflammatory skin disease. IL-13 contributes significantly to the pathogenesis of AD in several ways, and beneficial results have been demonstrated with anti-IL-13 therapies. Currently, the only monoclonal antibody (mAb) approved for AD treatment is dupilumab, an antagonist of the IL-4 receptor alpha (IL-4Rα) subunit common to IL-4 and IL-13 receptors, but clinical trials evaluating anti-IL-13 mAbs are providing promising results. The topics of this review will be mAbs targeting IL-13 for the treatment of AD such as dupilumab, tralokinumab and lebrikizumab, small molecules targeting the IL-13 pathway, and a brief explanation of therapies targeting IL-13 for the treatment of other skin diseases.

Regulation of entheseal IL-23 expression by IL-4 and IL-13 as an explanation for arthropathy development under dupilumab therapy.

OBJECTIVES: Dupilumab blocks the IL-4 receptor (IL-4R) and thus signalling of the 'Th2' cytokines IL-4 and IL-13. It has a license to treat atopic eczema and was recently linked to emergent enthesitis and psoriasis. We investigated the cellular and functional basis for how IL-4/IL-13 regulates the IL-23-IL-17 axis in entheseal stromal, myeloid and lymphocyte cells. METHODS: Immunohistochemistry was performed on healthy enthesis samples from patients undergoing elective spinal surgery to investigate entheseal tissue IL-4R expression and cytokine expression by intracellular flow cytometry for IL-4 and IL-13. Digested human enthesis samples were stimulated with lipopolysaccharide (LPS) for IL-23 induction, either alone or with IL-4 or IL-13. Enthesis fibroblasts were stimulated with TNF and IL-17 with and without IL-4 or IL-13 to assess the effect on CCL20 secretion. Synovial fluid samples from PsA patients were also analysed by ELISA for levels of IL-4 and IL-13. RESULTS: The IL-4/IL-13 receptor was present in both the peri-entheseal bone and enthesis soft tissue, and entheseal-derived T cells produced basal levels of IL-4, but not IL-13. Both IL-4 and IL-13 attenuated LPS-induced entheseal IL-23 production. IL-4 also downregulated secretion of TNF/IL-17A-induced CCL20 from entheseal fibroblasts. Both IL-13 and IL-4 were also detectable in the synovial fluid of PsA patients. We also noted a seronegative inflammatory oligoarthritis whilst under dupilumab therapy. CONCLUSION: Our findings suggest a previously unknown protective role for IL-4/IL-13 in entheseal induction of the IL-23-IL-17 axis. These findings point towards a novel explanation for IL-13 pathway single nucleotide polymorphisms in PsA and also a molecular explanation for why anti-IL-4/IL-13 therapy may induce musculoskeletal entheseal pathology as recently reported.

N-Glycosylation Regulates Chitinase 3-like-1 and IL-13 Ligand Binding to IL-13 Receptor α2.

Chitinase 3-like-1 (Chi3l1) and IL-13 are both ligands of IL-13 receptor α2 (IL-13Rα2). The binding of the former activates mitogen-activated protein kinase, AKT, and Wnt/ß-catenin signaling, and plays important roles in innate and adaptive immunity, cellular apoptosis, oxidative injury, allergic inflammation, tumor metastasis and wound healing, fibrosis, and repair in the lung. In contrast, the latter binding is largely a decoy event that diminishes the effects of IL-13. Here, we demonstrate that IL-13Rα2 N-glycosylation is a critical determinant of which ligand binds. Structure-function evaluations demonstrated that Chi3l1-IL-13Rα2 binding was increased when sites of N-glycosylation are mutated, and studies with tunicamycin and Peptide:N-glycosidase F (PNGase F) demonstrated that Chi3l1-IL-13Rα2 binding and signaling were increased when N-glycosylation was diminished. In contrast, structure-function experiments demonstrated that IL-13 binding to IL-13Rα2 was dependent on each of the four sites of N-glycosylation in IL-13Rα2, and experiments with tunicamycin and PNGase F demonstrated that IL-13-IL-13Rα2 binding was decreased when IL-13Rα2 N-glycosylation was diminished. Studies with primary lung epithelial cells also demonstrated that Chi3l1 inhibited, whereas IL-13 stimulated, N-glycosylation as evidenced by the ability of Chi3l1 to inhibit and IL-13 to stimulate the subunits of the oligosaccharide complex A and B (STT3A and STT3B). These studies demonstrate that N-glycosylation is a critical determinant of Chi3l1 and IL-13 binding to IL-13Rα2, and highlight the ability of Chi3l1 and IL-13 to alter key elements of the N-glycosylation apparatus in a manner that would augment their respective binding.