PERINEURIUM TALIN IMMUNOREACTIVITY DECREASES IN DIABETIC NEUROPATHY

We studied the immunolocalization of Dp116 (a 116 kDa protein product of the dystrophin gene), vinculin, talin, vimentin, desmin, spectrin a nd titin in the sural nerve biopsies of 25 patients with peripheral ne uropathies of different origin. 4 patients presented with HMSN type 1, 4 with HMSN type 2, 2 with HNPP, 4 with CIDP, 5 with chronic axonal n europathy of unknown origin, 3 with vasculitic neuropathy, 3 with diab etic neuropathy. Expression and localization of Dp116, vinculin, vimen tin, desmin, spectrin and titin did not differ from normal control cas es. Spectrin and titin immunoreactivities were absent and desmin was o ccasionally found in few epineurial vessels. A thin rim of Dp116 bindi ng surrounded the outermost layer of myelin sheaths. Perineurium and e pineurial vessels stained deeply for vinculin. Vimentin immunoreactivi ty was seen in all endoneurial, perineurial and epineurial cells. Immu noreactivity for talin was normally found at endoneurial and epineuria l vessel walls, perineurial cells and epineurial fibroblasts in all th e sural nerves except diabetic nerves. In the latter, whereas talin bi nding was normal in the vessel walls and epineurial fibroblasts, it wa s markedly reduced in the perineurium. On immunoblot, two bands at 235 and 190 kDa were found in the sural nerves with the antibody anti-tal in, and both were reduced only in the patients with diabetic neuropath y. We postulate that decreased perineurium talin in diabetic polyneuro pathy may be related to the known alterations of the tight junctions o f the perineurial cells, which have been proposed to be a contributory factor to impaired permeability barrier properties. (C) 1997 Elsevier Science B.V.