Targeting KDM4B attenuates IL-13-mediated fibrosis in bronchial fibroblasts of severe asthmatics
Khuloud Bajbouj1, Rakhee K Ramakrishnan1, Huda Alketbi2, Lina Sahnoon2, Jasmin Shafarin2, Mahmood Y Hachim3, Ronald Olivenstein4, Qutayba Hamid5
1 Basic Medical Sciences, College of Medicine; Sharjah Institute for Medical Research, University of Sharjah, Sharjah, United Arab Emirates
2 Sharjah Institute for Medical Research, University of Sharjah, Sharjah, United Arab Emirates
3 Basic Medical Sciences, College of Medicine, Mohammed Bin Rashid University of Medicine and Health Sciences, Dubai, United Arab Emirates
4 Department of Medicine, Meakins-Christie Laboratories, McGill University, Montreal, QC, Canada
5 Basic Medical Sciences, College of Medicine; Sharjah Institute for Medical Research, University of Sharjah, Sharjah, United Arab Emirates; Department of Medicine, Meakins-Christie Laboratories, McGill University, Montreal, QC, Canada
Prof. Qutayba Hamid
Clinical Sciences Department, College of Medicine, University of Sharjah, Sharjah
Source of Support: None, Conflict of Interest: None
Background: Asthma is a heterogeneous disorder characterized by chronic inflammation and remodeling of the airways. Asthma is mainly driven by type 2 immune responses, where interleukin-13 (IL-13) plays a key role in asthma pathogenesis. KDM4B/JMJD2B is an IL-13-regulated epigenetic modifier in asthmatic airway fibroblasts. Therefore, this study aimed to target KDM4B to potentially alleviate IL-13-mediated fibrosis in asthma.
Methods: Bronchial fibroblasts isolated from asthmatic individuals were stimulated with IL-13 and treated with JIB-04, a pan-selective inhibitor of histone demethylase(s). The expression of extracellular matrix (ECM) markers was assessed using quantitative real-time polymerase chain reaction, Western blotting, and matrix metalloproteinase (MMP) activity assay. Chromatin immunoprecipitation assay was used to determine the binding of KDM4B and H3K36me3 to promoter region of tissue inhibitor of metalloproteinase-2 (TIMP-2). KDM4B knockdown was performed to confirm its direct role on TIMP/MMP regulation.
Results: JIB-04 inhibited KDM4B activity by reducing the demethylation of its downstream target, H3K36me3, in asthmatic fibroblasts. Inhibition of KDM4B significantly affected the viability of the bronchial fibroblasts at 48 h. KDM4B inhibition was further associated with the downregulation of ECM proteins such as MMP-2, MMP-9, collagen-1, and fibronectin, and upregulation of TIMP-2, at both the gene and protein levels. This was accompanied by the inhibition of IL-13-mediated fibrotic response. JIB-04 further prevented KDM4B association and enhanced H3K36 binding with promoter region of TIMP-2 leading to its increased transcription. KDM4B knockdown further resulted in inducing TIMP-2 expression and inhibited MMP-9 activation.
Conclusion: Therapeutic targeting of KDM4B using JIB-04 is a promising candidate to alleviate IL-13-mediated responses in chronic disorders such as asthma.