Navitoclax inhibits senescence markers in precision cut lung slices from COPD patients

<bold>Background:</bold> COPD is associated with accelerated aging and increased cellular senescence. Senescent cells show increased levels of the cell cycle inhibitors p16^INK4a and p21^CIP1, with secretion of Senescence Associated Secretory Phenotype (SASP) cytokines, chemokines and proteases with up-regulation of the anti-apoptotic proteins BCL-2 and BCL-X_L. Navitoclax is a senolytic compound that inhibits BCL-2/X_L and drives senescent cells toward apoptosis which can then be removed via efferocytosis. <bold>Hypothesis:</bold> Navitoclax will reduce senescent cells in COPD precision cut lung slices (PCLS). <bold>Methods:</bold> Human lung tissue was inflated with 3%(v/v) agarose, and 300µm PCLS generated using a Krumdiek tissue slicer. PCLS were washed and incubated with Navitoclax 0.1-3µM for 48h. Expression of p16^INK4a and p21^CIP1 was measured by immunohistochemistry and RT-qPCR and cell viability by MTT. <bold>Results:</bold> Navitoclax significantly reduced expression of both p16^INK4a (Fig. 1A) and p21^CIP1 (Fig. 1B) in PCLS from COPD patients at 0.3- 3μM by ≈30%. This was confirmed at the protein level by immunohistochemistry, which showed reduction of these senescence markers particularly in small airway epithelial cells. The MTT assay showed no significant effect on PCLS viability. <fig><object-id>erj;64/suppl_68/PA345/F1</object-id><object-id>F1</object-id><object-id>F1</object-id><graphic></graphic></fig> <bold>Conclusion:</bold> Navitoclax reduces the levels of senescent markers in PCLS and may therefore provide a novel therapy for the treatment of COPD.