Silencing TSLP expression with a lung-targeted RNAi molecule suppresses pulmonary allergic inflammation

Introduction: Thymic stromal lymphopoietin (TSLP), an epithelial cell-derived cytokine is a key regulator of inflammatory pathways in asthma by activating Th2 cells, ILC2, and myeloid dendritic cells (mDCs) via the TSLP receptor (TSLPR). Here, we utilize a pulmonary epithelium-targeted siRNA delivery platform to silence TSLP expression in the lung and evaluate anti-inflammatory effects in a rat model of allergic asthma. Methods: Integrin-targeted siRNAs designed to specifically silence rodent TSLP mRNA were intratracheally (IT) delivered to rats prior to the Alternaria challenge followed by serial evaluation of lung inflammation indices. The efficacy of human cross-reactive TSLP siRNA conjugates was evaluated in the AAV9-CAG-hTSLP transduced mouse model. Results: In the rat, IT dosed siRNA conjugates silenced 50-60% of lung TSLP expression for over 2 months post-dose and limited lung inflammation in response to the Alternaria challenge, significantly reducing BAL Th2 cytokines and inflammatory cell counts. In AAV-transduced mice expressing human TSLP in the lung, human cross-reactive siRNAs silenced >80% TSLP protein expression. Conclusion: Inhaled epithelial-targeted siRNAs that effectively silence TSLP and limit pulmonary inflammation offer a novel approach for the treatment of allergic asthma.