Small bowel enterocyte apoptosis and proliferation are increased in the elderly

It is known that in the elderly the small bowel does not reveal structural and functional deteriorations in normal conditions, whereas the absorptive function is impaired in stress conditions.

The balance between enterocyte apoptosis and proliferation being responsible for the maintenance of tissue size, mucosal morphology and function in the gastrointestinal tract, the aim of our study was to evaluate the rates of enterocyte apoptosis and proliferation in the duodenal mucosa of aged human beings in comparison to adults.

For this purpose, the terminal deoxynucleotidyl transferase-mediated digoxigenin-deoxyuridine triphosphate nick end labelling (TUNEL) technique and immunohistochemistry for MIB-1 detection were applied on histological sections of endoscopic duodenal biopsy specimens obtained from 12 healthy elderly subjects (mean age 77.6 years; M/F 7/5) and 12 healthy adult subjects (mean age 37.7 years; M/F 8/4). Counts were performed, at a constant magnification (x200), by computer-aided analysis and the results expressed as median percentages of positive enterocytes.

The results showed a significant increase in enterocyte apoptosis in the elderly (15.3 vs. 2.1% in the adults, p < 0.001) which was positively correlated (r(s) = 0.65, p < 0.05) with a significant increase in enterocyte proliferation (37.7 vs. 15.8% in the adults, p < 0.0001).

These data suggest that the maintenance of mucosal architecture throughout the process of aging is due to either a hyperproliferative state or an exaggerated apoptosis with a consequent cellular immaturity, which may impair the absorptive function observed in stress conditions.