Plasma fibronectin in French centenarians

Plasma fibronectin was shown to increase with age, the difference between individuals (the SD of the mean) also increases with age. Fibronectin is highly sensitive to proteolytic degradation and several of the degradation products were shown to have noxious effects as proper proteolytic activity, activation of IL-1 and collagenase expression and also activation of fibronectin biosynthesis. It was therefore interesting to compare the plasma fibronectin values of centenarians in relatively good health with an elderly population in a geriatric hospital, somewhat younger (70–96 years) but with a variety of pathologies. A third population of men and women between 59 and 70 in good health (the EVA-epidemiological study) was also used for comparison. Plasma fibronectin was determined by a specific and highly sensitive Elisa assay. Fibronectin fragments were characterized by immunoblot. It could be shown that plasma fibronectin in centenarians had a lower distribution with lower average values than the geriatric population. Fibronectin fragments could be demonstrated in the plasma of a selection of geriatric patents but not in the plasma of centenarians. These results suggest a more moderate increase of plasma fibronectin in the relatively healthy centenarians as compared to a younger but pathological population. They also show that the plasma fibronectin of the investigated centenarians was better protected from proteolytic degradation than in the geriatric population. The above results also confirm the contention that epigenetic mechanisms such as an age-dependent increase of fibronectin synthesis and degradation and the potential noxious effects of degradation products may well play an important role in the age-dependent decline of physiological functions.