The IκB kinase inhibitor ACHP strongly attenuates TGF β1‐induced myofibroblast formation and collagen synthesis

Abstract Excessive accumulation of a collagen‐rich extracellular matrix ( ECM ) by myofibroblasts is a characteristic feature of fibrosis, a pathological state leading to serious organ dysfunction. Transforming growth factor beta1 ( TGF β1) is a strong inducer of myofibroblast formation and subsequent collagen production. Currently, there are no remedies for the treatment of fibrosis. Activation of the nuclear factor kappa B ( NF ‐κB) pathway by phosphorylating IκB with the enzyme IκB kinase ( IKK ) plays a major role in the induction of fibrosis. ACHP {2‐Amino‐6‐[2‐(cyclopropylmethoxy)‐6‐hydroxyphenyl]‐4‐(4‐piperidinyl)‐3 pyridinecarbonitrile}, a selective inhibitor of IKK , prohibits the activation of the NF ‐κB pathway. It is not known whether ACHP has potential anti‐fibrotic properties. Using adult human dermal and lung fibroblasts we have investigated whether ACHP has the ability to inhibit the TGF β1‐induced transition of fibroblasts into myofibroblasts and its excessive synthesis of ECM . The presence of ACHP strongly suppressed the induction of the myofibroblast markers alpha‐smooth muscle actin (α SMA ) and SM 22α, as well as the deposition of the ECM components collagen type I and fibronectin. Furthermore, post‐treatment with ACHP partly reversed the expression of α SMA and collagen type I production. Finally, ACHP suppressed the expression of the three collagen‐modifying enzymes lysyl hydroxylase ( PLOD 1 , PLOD 2 and PLOD 3 ) in dermal fibroblasts, but did not do so in lung fibroblasts. We conclude that the IKK inhibitor ACHP has potent antifibrotic properties, and that the NF ‐κB pathway plays an important role in myofibroblast biology.