SIRT1 and chronic obstructive pulmonary disease: This PDE4 inhibitor is typically used in the treatment of chronic obstructive pulmonary disease (COPD) and in this case acts by the indirect inhibition of PTP1B, with the effects mediated by the crosstalk between the CREB/BDNF/TrkB and SIRT1/PTP1B/IGF1 signaling pathways [169].