IL-1R3 blockade broadly attenuates the functions of six members of the IL-1 family, revealing their contribution to models of disease.

Interleukin (IL)-1R3 is the co-receptor in three signaling pathways that involve six cytokines of the IL-1 family (IL-1α, IL-1ß, IL-33, IL-36α, IL-36ß and IL-36γ). In many diseases, multiple cytokines contribute to disease pathogenesis. For example, in asthma, both IL-33 and IL-1 are of major importance, as are IL-36 and IL-1 in psoriasis. We developed a blocking monoclonal antibody (mAb) to human IL-1R3 (MAB-hR3) and demonstrate here that this antibody specifically inhibits signaling via IL-1, IL-33 and IL-36 in vitro. Also, in three distinct in vivo models of disease (crystal-induced peritonitis, allergic airway inflammation and psoriasis), we found that targeting IL-1R3 with a single mAb to mouse IL-1R3 (MAB-mR3) significantly attenuated heterogeneous cytokine-driven inflammation and disease severity. We conclude that in diseases driven by multiple cytokines, a single antagonistic agent such as a mAb to IL-1R3 is a therapeutic option with considerable translational benefit.

LAMP3 deficiency affects surfactant homeostasis in mice.

Lysosome-associated membrane glycoprotein 3 (LAMP3) is a type I transmembrane protein of the LAMP protein family with a cell-type-specific expression in alveolar type II cells in mice and hitherto unknown function. In type II pneumocytes, LAMP3 is localized in lamellar bodies, secretory organelles releasing pulmonary surfactant into the extracellular space to lower surface tension at the air/liquid interface. The physiological function of LAMP3, however, remains enigmatic. We generated Lamp3 knockout mice by CRISPR/Cas9. LAMP3 deficient mice are viable with an average life span and display regular lung function under basal conditions. The levels of a major hydrophobic protein component of pulmonary surfactant, SP-C, are strongly increased in the lung of Lamp3 knockout mice, and the lipid composition of the bronchoalveolar lavage shows mild but significant changes, resulting in alterations in surfactant functionality. In ovalbumin-induced experimental allergic asthma, the changes in lipid composition are aggravated, and LAMP3-deficient mice exert an increased airway resistance. Our data suggest a critical role of LAMP3 in the regulation of pulmonary surfactant homeostasis and normal lung function.

IL-37 regulates allergic inflammation by counterbalancing pro-inflammatory IL-1 and IL-33.

BACKGROUND: Children with asthma have impaired production of interleukin (IL) 37; in mice, IL-37 reduces hallmarks of experimental allergic asthma (EAA). However, it remains unclear how IL-37 exerts its inhibitory properties in asthma. This study aimed to identify the mechanism(s) by which IL-37 controls allergic inflammation. METHODS: IL-37 target cells were identified by single-cell RNA-seq of IL-1R5 and IL-1R8. Airway tissues were isolated by laser-capture microdissection and examined by microarray-based gene expression analysis. Mononuclear cells (MNC) and airway epithelial cells (AECs) were isolated and stimulated with allergen, IL-1ß, or IL-33 together with recombinant human (rh) IL-37. Wild-type, IL-1R1- and IL-33-deficient mice with EAA were treated with rhIL-37. IL-1ß, IL-33, and IL-37 levels were determined in sputum and nasal secretions from adult asthma patients without glucocorticoid therapy. RESULTS: IL-37 target cells included AECs, T cells, and dendritic cells. In mice with EAA, rhIL-37 led to differential expression of >90 genes induced by IL-1ß and IL-33. rhIL-37 reduced production of Th2 cytokines in allergen-activated MNCs from wild-type but not from IL-1R1-deficient mice and inhibited IL-33-induced Th2 cytokine release. Furthermore, rhIL-37 attenuated IL-1ß- and IL-33-induced pro-inflammatory mediator expression in murine AEC cultures. In contrast to wild-type mice, hIL-37 had no effect on EAA in IL-1R1- or IL-33-deficient mice. We also observed that expression/production ratios of both IL-1ß and IL-33 to IL-37 were dramatically increased in asthma patients compared to healthy controls. CONCLUSION: IL-37 downregulates allergic airway inflammation by counterbalancing the disease-amplifying effects of IL-1ß and IL-33.

Poly(inosinic-cytidylic) acid-triggered exacerbation of experimental asthma depends on IL-17A produced by NK cells.

Viral infection of the respiratory tract represents the major cause of acute asthma exacerbations. dsRNA is produced as an intermediate during replication of respiratory viruses and triggers immune responses via TLR3. This study aimed at clarifying the mechanisms underlying TLR3 triggered exacerbation of experimental allergic asthma. The TLR3 ligand poly(inosinic-cytidylic) acid was applied intranasally to mice with already established experimental allergic asthma. Airway inflammation, cytokine expression, mucus production, and airway reactivity was assessed in wild-type, IL-17A, or IL-23p19-deficient, and in NK cell-depleted mice. Local application of poly(inosinic-cytidylic) acid exacerbated experimental allergic asthma in mice as characterized by enhanced release of proinflammatory cytokines, aggravated airway inflammation, and increased mucus production together with pronounced airway hyperresponsiveness. This was further associated with augmented production of IL-17 by Th17 cells and NK cells. Whereas experimental exacerbation could be induced in IL-23p19-deficient mice lacking mature, proinflammatory Th17 cells, this was not possible in mice lacking IL-17A or in NK cell-depleted animals. These experiments indicate a central role for IL-17 derived from NK cells but not from Th17 cells in the pathogenesis of virus-triggered exacerbation of experimental asthma.

An antibody to IL-1 receptor 7 protects mice from LPS-induced tissue and systemic inflammation.

Introduction: Interleukin-18 (IL-18), a pro-inflammatory cytokine belonging to the IL-1 Family, is a key mediator ofautoinflammatory diseases associated with the development of macrophage activation syndrome (MAS).High levels of IL-18 correlate with MAS and COVID-19 severity and mortality, particularly in COVID-19patients with MAS. As an inflammation inducer, IL-18 binds its receptor IL-1 Receptor 5 (IL-1R5), leadingto the recruitment of the co-receptor, IL-1 Receptor 7 (IL-1R7). This heterotrimeric complex subsequentlyinitiates downstream signaling, resulting in local and systemic inflammation. Methods: We reported earlier the development of a novel humanized monoclonal anti-human IL-1R7 antibody whichspecifically blocks the activity of human IL-18 and its inflammatory signaling in human cell and wholeblood cultures. In the current study, we further explored the strategy of blocking IL-1R7 inhyperinflammation in vivo using animal models. Results: We first identified an anti-mouse IL-1R7 antibody that significantly suppressed mouse IL-18 andlipopolysaccharide (LPS)-induced IFNg production in mouse splenocyte and peritoneal cell cultures. Whenapplied in vivo, the antibody reduced Propionibacterium acnes and LPS-induced liver injury and protectedmice from tissue and systemic hyperinflammation. Importantly, anti-IL-1R7 significantly inhibited plasma,liver cell and spleen cell IFNg production. Also, anti-IL-1R7 downregulated plasma TNFa, IL-6, IL-1b,MIP-2 production and the production of the liver enzyme ALT. In parallel, anti-IL-1R7 suppressed LPSinducedinflammatory cell infiltration in lungs and inhibited the subsequent IFNg production andinflammation in mice when assessed using an acute lung injury model. Discussion: Altogether, our data suggest that blocking IL-1R7 represents a potential therapeutic strategy to specificallymodulate IL-18-mediated hyperinflammation, warranting further investigation of its clinical application intreating IL-18-mediated diseases, including MAS and COVID-19.

The Dual Role of the Airway Epithelium in Asthma: Active Barrier and Regulator of Inflammation.

Chronic airway inflammation is the cornerstone on which bronchial asthma arises, and in turn, chronic inflammation arises from a complex interplay between environmental factors such as allergens and pathogens and immune cells as well as structural cells constituting the airway mucosa. Airway epithelial cells (AECs) are at the center of these processes. On the one hand, they represent the borderline separating the body from its environment in order to keep inner homeostasis. The airway epithelium forms a multi-tiered, self-cleaning barrier that involves an unstirred, discontinuous mucous layer, the dense and rigid mesh of the glycocalyx, and the cellular layer itself, consisting of multiple, densely interconnected cell types. On the other hand, the airway epithelium represents an immunologically highly active tissue once its barrier has been penetrated: AECs play a pivotal role in releasing protective immunoglobulin A. They express a broad spectrum of pattern recognition receptors, enabling them to react to environmental stressors that overcome the mucosal barrier. By releasing alarmins-proinflammatory and regulatory cytokines-AECs play an active role in the formation, strategic orientation, and control of the subsequent defense reaction. Consequently, the airway epithelium is of vital importance to chronic inflammatory diseases, such as asthma.

More Than Just a Barrier: The Immune Functions of the Airway Epithelium in Asthma Pathogenesis.

Allergic bronchial asthma is a chronic disease of the airways that is characterized by symptoms like respiratory distress, chest tightness, wheezing, productive cough, and acute episodes of broncho-obstruction. This symptom-complex arises on the basis of chronic allergic inflammation of the airway wall. Consequently, the airway epithelium is central to the pathogenesis of this disease, because its multiple abilities directly have an impact on the inflammatory response and thus the formation of the disease. In turn, its structure and functions are markedly impaired by the inflammation. Hence, the airway epithelium represents a sealed, self-cleaning barrier, that prohibits penetration of inhaled allergens, pathogens, and other noxious agents into the body. This barrier is covered with mucus that further contains antimicrobial peptides and antibodies that are either produced or specifically transported by the airway epithelium in order to trap these particles and to remove them from the body by a process called mucociliary clearance. Once this first line of defense of the lung is overcome, airway epithelial cells are the first cells to get in contact with pathogens, to be damaged or infected. Therefore, these cells release a plethora of chemokines and cytokines that not only induce an acute inflammatory reaction but also have an impact on the alignment of the following immune reaction. In case of asthma, all these functions are impaired by the already existing allergic immune response that per se weakens the barrier integrity and self-cleaning abilities of the airway epithelium making it more vulnerable to penetration of allergens as well as of infection by bacteria and viruses. Recent studies indicate that the history of allergy- and pathogen-derived insults can leave some kind of memory in these cells that can be described as imprinting or trained immunity. Thus, the airway epithelium is in the center of processes that lead to formation, progression and acute exacerbation of asthma.