Anti-βc mAb CSL311 inhibits human nasal polyp pathophysiology in a humanized mouse xenograft model

Dual inhibition of airway inflammation and fibrosis by common β cytokine receptor blockade

BACKGROUND

Patients with severe asthma can present with eosinophilic type 2 (T2), neutrophilic, or mixed inflammation that drives airway remodeling and exacerbations and represents a major treatment challenge. The common β (βc) receptor signals for 3 cytokines, GM-CSF, IL-5, and IL-3, which collectively mediate T2 and neutrophilic inflammation.

OBJECTIVE

To determine the pathogenesis of βc receptor-mediated inflammation and remodeling in severe asthma and to investigate βc antagonism as a therapeutic strategy for mixed granulocytic airway disease.

METHODS

βc gene expression was analyzed in bronchial biopsy specimens from patients with mild-to-moderate and severe asthma. House dust mite extract and Aspergillus fumigatus extract (ASP) models were used to establish asthma-like pathology and airway remodeling in human βc transgenic mice. Lung tissue gene expression was analyzed by RNA sequencing. The mAb CSL311 targeting the shared cytokine binding site of βc was used to block βc signaling.

RESULTS

βc gene expression was increased in patients with severe asthma. CSL311 potently reduced lung neutrophils, eosinophils, and interstitial macrophages and improved airway pathology and lung function in the acute steroid-resistant house dust mite extract model. Chronic intranasal ASP exposure induced airway inflammation and fibrosis and impaired lung function that was inhibited by CSL311. CSL311 normalized the ASP-induced fibrosis-associated extracellular matrix gene expression network and strongly reduced signatures of cellular inflammation in the lung.

CONCLUSIONS

βc cytokines drive steroid-resistant mixed myeloid cell airway inflammation and fibrosis. The anti-βc antibody CSL311 effectively inhibits mixed T2/neutrophilic inflammation and severe asthma-like pathology and reverses fibrosis gene signatures induced by exposure to commonly encountered environmental allergens.

Translating the biology of β common receptor-engaging cytokines into clinical medicine

The family of cytokines that comprises IL-3, IL-5, and GM-CSF was discovered over 30 years ago, and their biological activities and resulting impact in clinical medicine has continued to expand ever since. Originally identified as bone marrow growth factors capable of acting on hemopoietic progenitor cells to induce their proliferation and differentiation into mature blood cells, these cytokines are also recognized as key mediators of inflammation and the pathobiology of diverse immunologic diseases. This increased understanding of the functional repertoire of IL-3, IL-5, and GM-CSF has led to an explosion of interest in modulating their functions for clinical management. Key to the successful clinical translation of this knowledge is the recognition that these cytokines act by engaging distinct dimeric receptors and that they share a common signaling subunit called β-common or βc. The structural determination of how IL-3, IL-5, and GM-CSF interact with their receptors and linking this to their differential biological functions on effector cells has unveiled new paradigms of cell signaling. This knowledge has paved the way for novel mAbs and other molecules as selective or pan inhibitors for use in different clinical settings.

Targeting the human β c receptor inhibits inflammatory myeloid cells and lung injury caused by acute cigarette smoke exposure

Background and objective

Chronic obstructive pulmonary disease (COPD) is a devastating disease commonly caused by cigarette smoke (CS) exposure that drives tissue injury by persistently recruiting myeloid cells into the lungs. A significant portion of COPD patients also present with overlapping asthma pathology including eosinophilic inflammation. The β_c cytokine family includes granulocyte monocyte‐colony‐stimulating factor, IL‐5 and IL‐3 that signal through their common receptor subunit β_c to promote the expansion and survival of multiple myeloid cells including monocytes/macrophages, neutrophils and eosinophils.

Methods

We have used our unique human β_c receptor transgenic (hβ_cTg) mouse strain that expresses human β_c instead of mouse β_c and β_IL3 in an acute CS exposure model. Lung tissue injury was assessed by histology and measurement of albumin and lactate dehydrogenase levels in the bronchoalveolar lavage (BAL) fluid. Transgenic mice were treated with an antibody (CSL311) that inhibits human β_c signalling.

Results

hβ_cTg mice responded to acute CS exposure by expanding blood myeloid cell numbers and recruiting monocyte‐derived macrophages (cluster of differentiation 11b⁺ [CD11b⁺] interstitial and exudative macrophages [IM and ExM]), neutrophils and eosinophils into the lungs. This inflammatory response was associated with lung tissue injury and oedema. Importantly, CSL311 treatment in CS‐exposed mice markedly reduced myeloid cell numbers in the blood and BAL compartment. Furthermore, CSL311 significantly reduced lung CD11b⁺ IM and ExM, neutrophils and eosinophils, and this decline was associated with a significant reduction in matrix metalloproteinase‐12 (MMP‐12) and IL‐17A expression, tissue injury and oedema.

Conclusion

This study identifies CSL311 as a therapeutic antibody that potently inhibits immunopathology and lung injury caused by acute CS exposure.

Myeloid cells, including macrophages, neutrophils and eosinophils, are important cellular drivers of inflammation and injury. In this study, we blocked granulocyte monocyte‐colony stimulating factor, IL‐5 and IL‐3 signalling with an anti‐β_c receptor antibody (CSL311), which greatly reduced lung inflammation and injury in a pre‐clinical model of acute cigarette smoke exposure.

Blocking the human common beta subunit of the GM-CSF, IL-5 and IL-3 receptors markedly reduces hyperinflammation in ARDS models

Acute respiratory distress syndrome (ARDS) is triggered by various aetiological factors such as trauma, sepsis and respiratory viruses including SARS-CoV-2 and influenza A virus. Immune profiling of severe COVID-19 patients has identified a complex pattern of cytokines including granulocyte macrophage-colony stimulating factor (GM-CSF) and interleukin (IL)-5, which are significant mediators of viral-induced hyperinflammation. This strong response has prompted the development of therapies that block GM-CSF and other cytokines individually to limit inflammation related pathology. The common cytokine binding site of the human common beta (β_c) receptor signals for three inflammatory cytokines: GM-CSF, IL-5 and IL-3. In this study, β_c was targeted with the monoclonal antibody (mAb) CSL311 in engineered mice devoid of mouse β_c and β_IL-3 and expressing human β_c (hβ_cTg mice). Direct pulmonary administration of lipopolysaccharide (LPS) caused ARDS-like lung injury, and CSL311 markedly reduced lung inflammation and oedema, resulting in improved oxygen saturation levels in hβ_cTg mice. In a separate model, influenza (HKx31) lung infection caused viral pneumonia associated with a large influx of myeloid cells into the lungs of hβ_cTg mice. The therapeutic application of CSL311 potently decreased accumulation of monocytes/macrophages, neutrophils, and eosinophils without altering lung viral loads. Furthermore, CSL311 treatment did not limit the viral-induced expansion of NK and NKT cells, or the tissue expression of type I/II/III interferons needed for efficient viral clearance. Simultaneously blocking GM-CSF, IL-5 and IL-3 signalling with CSL311 may represent an improved and clinically applicable strategy to reducing hyperinflammation in the ARDS setting.

Targeting the Human βc Receptor Inhibits Contact Dermatitis in a Transgenic Mouse Model

Allergic contact dermatitis (ACD) is a prevalent and poorly controlled inflammatory disease caused by skin infiltration of T cells and granulocytes. The beta common (β_c) cytokines GM-CSF, IL-3, and IL-5 are powerful regulators of granulocyte function that signal through their common receptor subunit β_c, a property that has made β_c an attractive target to simultaneously inhibit these cytokines. However, the species specificity of β_c has precluded testing of inhibitors of human β_c in mouse models. To overcome this problem, we developed a human β_c receptor transgenic mouse strain with a hematopoietic cell‒specific expression of human β_c instead of mouse β_c. Human β_c receptor transgenic cells responded to mouse GM-CSF and IL-5 but not to IL-3 in vitro and developed tissue pathology and cellular inflammation comparable with those in wild-type mice in a model of ACD. Similarly, Il3^-/- mice developed ACD pathology comparable with that of wild-type mice. Importantly, the blocking anti-human β_c antibody CSL311 strongly suppressed ear pinna thickening and histopathological changes typical of ACD and reduced accumulation of neutrophils, mast cells, and eosinophils in the skin. These results show that GM-CSF and IL-5 but not IL-3 are major mediators of ACD and define the human β_c receptor transgenic mouse as a unique platform to test the inhibitors of β_c in vivo.

Understanding mast cell heterogeneity at single cell resolution

Mast cells (MC)s are evolutionarily conserved, tissue-resident immune cells with diverse roles in allergy, cancer, and protection from infection by helminths and microorganisms. The significant diversity in MC development and tissue-specific functional characteristics has recently begun to be understood. Exciting developments in single-cell-based RNA, protein, and chromatin profiling technologies offer new opportunities to characterize MC heterogeneity and to uncover novel MC functions and subtypes; these developments might lead to new and clinically effective therapies for certain pathologies. In this review, we provide an overview of the current understanding of MC development and heterogeneity and discuss new insights gained from single-cell-based studies that may lead to future research directions and therapeutic opportunities.

Regulation of Eosinophilia in Asthma-New Therapeutic Approaches for Asthma Treatment

Asthma is a complex and chronic inflammatory disease of the airways, characterized by variable and recurring symptoms, reversible airflow obstruction, bronchospasm, and airway eosinophilia. As the pathophysiology of asthma is becoming clearer, the identification of new valuable drug targets is emerging. IL-5 is one of these such targets because it is the major cytokine supporting eosinophilia and is responsible for terminal differentiation of human eosinophils, regulating eosinophil proliferation, differentiation, maturation, migration, and prevention of cellular apoptosis. Blockade of the IL-5 pathway has been shown to be efficacious for the treatment of eosinophilic asthma. However, several other inflammatory pathways have been shown to support eosinophilia, including IL-13, the alarmin cytokines TSLP and IL-33, and the IL-3/5/GM-CSF axis. These and other alternate pathways leading to airway eosinophilia will be described, and the efficacy of therapeutics that have been developed to block these pathways will be evaluated.