Immunohistological detection of pentosidine in the epiglottis:A contribution to molecular age estimation

Pentosidin (Pen) accumulates in various tissues with increasing age, among others in the epiglottis. So far, all published Pen concentrations in the epiglottis are based on the analysis of total tissue samples via HPLC. The morphological structures and proteins in which Pen accumulates remain unknown. Such insights would be of great importance for optimizing Pen based methods for age estimation, especially to overcome the problem of sample inhomogeneity in older individuals as source of error in age estimation based on Pen.Against this background, pentosidine was detected immunohistochemically in epiglottis tissue samples from 54 deceased individuals (age range: 6.5 months to 90 years). Staining intensity and intratissue distribution were evaluated.Pen was localized almost exclusively in the elastic cartilage of the epiglottis. Positive staining was most pronounced in fibers surrounding the chondrocytes, the staining pattern suggested a three-dimensional fiber network with a particularly dense fiber arrangement around these cells. Very similar findings were observed using Elastica-van Gieson staining of elastic fibers.Pen could not be detected immunohistologically in samples of young individuals up to an age of c. 35 years. From the mid-30s onward, staining became more frequent, with both staining intensity as well as the expansion of the areas with positive findings increasing with age.The observed immunohistological staining pattern provides new insights into Pen accumulation in the epiglottis. It is consistent with the assumption that Pen accumulates almost exclusively in elastic fibers, and here with a very high probability in elastin. The accuracy of age estimation based on Pen could be significantly improved if not - as is currently the case - total tissue samples are examined, but rather purified proteins in which Pen accumulates; elastin in the epiglottis was identified as a target protein for such an approach.