In this work, we focused on macrophages (observed in chronic active MS lesions, and active CALD lesions) as one of the main drivers of inflammatory processes in X-ALD or MS and investigated the potential of macrophage-targeted HDAC inhibition to promote peroxisomal VLCFA degradation and the phagocytosis of myelin debris and to interfere with immune cell recruitment. The gene discussed is HDAC9; the disease is myeloid sarcoma.