Hepatic retinopathy: morphological features of retinal glial (Müller) cells accompanying hepatic failure

More than 80 years ago, Alzheimer described changes in the brains of patients who had suffered hepatic failure. Astrocytes are primarily affected; their nuclei become swollen, their intermediate filament protein composition is altered and their cytoplasm becomes vacuolated. Cells with these features are called Alzheimer type II astrocytes and these changes have been attributed to the toxic effects of elevated ammonia levels. The present study investigates whether the dominant glia of another part of the central nervous system, the Müller cells of the retina, undergo similar changes. Retinae of patients who had died with symptoms of hepatic failure were processed for histology, histochemistry, and immunocytochemistry. Cell nuclei were measured from brain astrocytes (insula cortex), Müller cells, and retinal bipolar neurons. Hepatic failure resulted in the enlargement of nuclei in astrocytes and Müller cells, and the enhanced expression in Müller cells of glial fibrillary acidic protein, cathepsin D, and the beta-subunit of prolyl 4-hydroxylase (glial-p55). In some retinae, signs of gliosis were also observed. We conclude that increased levels of serum ammonia resulting from hepatic insufficiency cause changes in Müller cells that are similar to those seen in brain astrocytes. We term this condition hepatic retinopathy.