Receptor-Interacting Protein 2 Gene Silencing Attenuates Allergic Airway Inflammation

Abstract

Persistent activation of NF-κB has been associated with the development of asthma. Receptor-interacting protein 2 (Rip2) is a transcriptional product of NF-κB activation. It is an adaptor protein with serine/threonine kinase activity and has been shown to positively regulate NF-κB activity. We investigated potential protective effects of Rip2 gene silencing using small interfering RNA (siRNA) in an OVA-induced mouse asthma model. Rip2 protein level was found to be upregulated in allergic airway inflammation. A potent and selective Rip2 siRNA given intratracheally knocked down Rip2 expression in OVA-challenged lungs and reduced OVA-induced increases in total and eosinophil counts, and IL-4, IL-5, IL-13, IL-1β, IL-33, and eotaxin levels in bronchoalveolar lavage fluid. Rip2 silencing blocked OVA-induced inflammatory cell infiltration and mucus hypersecretion as observed in lung sections, and mRNA expression of ICAM-1, VCAM-1, E-selectin, RANTES, IL-17, IL-33, thymic stromal lymphopoietin, inducible NO synthase, and MUC5ac in lung tissues. In addition, elevation of serum OVA-specific IgE level in mouse asthma model was markedly suppressed by Rip2 siRNA, together with reduced IL-4, IL-5, and IL-13 production in lymph node cultures. Furthermore, Rip2 siRNA-treated mice produced significantly less airway hyperresponsiveness induced by methacholine. Mechanistically, Rip2 siRNA was found to enhance cytosolic level of IκBα and block p65 nuclear translocation and DNA-binding activity in lung tissues from OVA-challenged mice. Taken together, our findings clearly show that knockdown of Rip2 by gene silencing ameliorates experimental allergic airway inflammation, probably via interruption of NF-κB activity, confirming Rip2 a novel therapeutic target for the treatment of allergic asthma.

RIP kinases: key decision makers in cell death and innate immunity

“…RIP2 has also been implicated as a driver in experimental allergic airway inflammation by activating NFkB and inflammatory gene expression. 190 Furthermore, RIP2-deficient macrophages, although showing weaker inflammatory signalling, display increased lipid accumulation that contributes to more severe atherosclerosis in recipient mice, 191 implicating a potential role for RIP2 in cardiovascular disease.…”

Andrographolide Restores Steroid Sensitivity To Block Lipopolysaccharide/IFN-γ–Induced IL-27 and Airway Hyperresponsiveness in Mice

“…Briefly, the trachea was intubated with a cannula that was connected to the pneumotach, ventilator, and nebulizer. Lung resistance in response to PBS control and nebulized methacholine (2.5, 5, and 10 mg/ml) were recorded using a whole-body plethysmography chamber and the FinePointe data acquisition and analysis software (Buxco, Wilmington, NC), as described (21). Results are expressed as a percentage of the respective basal values in response to PBS.…”

“…Mice were anesthetized, and tracheotomy and cannulation were performed (21). Briefly, the trachea was intubated with a cannula that was connected to the pneumotach, ventilator, and nebulizer.…”

Vitamin E Isoform γ-Tocotrienol Downregulates House Dust Mite–Induced Asthma

“…Mice were anesthetized and tracheotomy was performed as previously described (19). Lung resistance (Rl) and Cdyn in response to increasing concentrations of nebulized methacholine (0.5-8.0 mg/ml) were recorded using the FinePointe data acquisition and analysis software (Buxco, Wilmington, NC).…”

“…Scoring of cell infiltration in H&E-stained lung sections was performed blinded as previously described (19). Relative intensity analyses of PAFS stain were also performed blinded as described (19), where the ratio of red over green stains was normalized to saline control, using the ImageJ software (National Institutes of Health, Bethesda, MD).…”