IMMUNOHISTOCHEMICAL LOCALIZATION OF UTROPHIN AND OTHER CYTOSKELETAL PROTEINS IN SKIN SMOOTH-MUSCLE IN NEUROMUSCULAR DISEASES

We investigated the immunohistochemical distribution of cytoskeletal p roteins in smooth muscles of 15 patients with Duchenne muscular dystro phy (DMD), 8 patients with Becker muscular dystrophy (BMD), 28 patient s with various neuromuscular diseases, and 2 normal controls, performi ng skin and muscle biopsies. Dystrophin immunostaining confirmed absen t reaction in thr arrector pill muscles of DMD patients, faint positiv e reaction in BMD patients, and strong dystrophin reaction in patients with other neuromuscular diseases and normal controls. Immunostaining of utrophin was positive with variable intensity in the arrector pill muscles in all DMD patients. In BMD patients, utrophin was faintly ex pressed in the arrector pill muscles in 2 cases, and negative in the o ther 5 patients. Zn the other cases of neuromuscular diseases and in n ormal controls, immunostaining for utrophin was negative in the arrect or pili muscles. Staining of the capillary endothelial cells and muscu lar Vessel walls was seen in normal controls, as well as in DMD, BMD, and other neuromuscular diseases. Vinculin, vimentin and desmin were e xpressed both in arrector pill smooth muscles and in vessel walls of p atients with dystrophinopathy and other neuromuscular diseases, as wel l as in normal controls. Thus utrophin is normally expressed in the sm ooth muscle of the vessels and its expression does not vary in neuromu scular diseases. On the contrary, in the arrector pili smooth muscle u trophin is not expressed in normal controls but it is in dystrophinopa thies, paralleling the findings in striated muscle, which expresses ut rophin in a reciprocal manner with respect to dystrophin.