What, in fact, causes wrinkles on the skin?
The ageing skin cells, keratinocytes and fibroblasts, after the changes in protein, they begin to behave abnormally and eventually accumulate in the human skin. They produce more metalloproteinase-like enzymes that damage proteins in the surrounding extracellular mass (matrix in which there are cells, lymph nodes, blood vessels and other associated skin structures). Moreover, ageing causes irreversible damage to the body’s proteins. The underlying mechanism behind this damage is glycation. A simple definition of glycation is the crosslinking of proteins and sugars to form non-functioning structures in the body. The process of glycation can be superficially seen as unsightly wrinkled skin (1).
The ageing cells also produce adhesion molecules that cause thickening of the walls of blood vessels and their stiffness (atherosclerosis). The ageing cells produce other additional degradative enzymes and anti-inflammatory cytokines, which act in distant parts of the body (they are transported through the blood). In this way, a relatively small amount of aged cells causes large changes in the function and integrity of the skin. The ageing cells accumulate in all organs and tissues where they suffer apoptosis (programmed cell death) and summon the degenerative processes of ageing. Moreover, the distortion of the microscopic environment by accumulated aging cells can be the reason for the increased incidence of malignant disease in older people.
Dr. Leonard Hayflick demonstrated in 1961 that cells can reach a limited number of cell divisions and then lose their ability of division. His well-known experiments have demonstrated that human fibroblasts (connective tissue cells) have the option of sharing (division) 60 to 80 times, fibroblasts of young people 30 to 40 times, and fibroblasts of older people, only 10 to 20 times. Carnosine extends the average life of fibroblasts in cultures, destroys their transformed (mutagenic) shapes and protects against aldehydes. At the same time, carnosine suppresses, at least in laboratory conditions, protein glycation and the formation of harmful cross-links of DNA/proteins (2).
The novel finding has shown that not only does orally taken carnosine is associated with skin rejuvenation, but also the topical formulations of carnosine hold potential for anti-ageing effect. Both topical carnosine solution and carnosine-based facial cream were shown to significantly reduce the formation of advanced glycation end-products (AGEs) in epidermis and dermis. As AGEs accumulation in skin results in loss of elasticity, firmness and skin tone, it is suggested that carnosine represents a promising agent in the cosmetic industry (3).
An early study dating back to 1986 concluded that carnosine supports wound healing. The underlying mechanism is probably due to the stimulating effect on histamine and beta-alanine induced collagen synthesis (4). A double-blind placebo-controlled study concluded that carnosine, when applied with Rhodiola rosea, results in the amelioration of skin dryness (5), while in combination with urea and arginine, topical application results in improved skin hydration and ameliorated dryness in patients with T2DM (6).
References:
- Hipkiss, A.R., Brownson, C., Bertani, M.F., Ruiz, E. and Ferro, A., 2002. Reaction of carnosine with aged proteins: another protective process?. Annals of the New York Academy of Sciences, 959(1), pp.285-294.
- McFarland, G.A. and Holliday, R., 1994. Retardation of the senescence of cultured human diploid fibroblasts by carnosine. Experimental cell research, 212(2), pp.167-175.
- Narda, M., Peno-Mazzarino, L., Krutmann, J., Trullas, C. and Granger, C., 2018. Novel Facial Cream Containing Carnosine Inhibits Formation of Advanced Glycation End-Products in Human Skin. Skin Pharmacology and Physiology, 31(6), pp.324-331.
- Nagai, K., Suda, T., Kawasaki, K. and Mathuura, S., 1986. Action of carnosine and β-alanine on wound healing. Surgery, 100(5), pp.815-821.
- Dieamant, G.D.C., Velazquez Pereda, M.D.C., Eberlin, S., Nogueira, C., Werka, R.M. and Queiroz, M.L.D.S., 2008. Neuroimmunomodulatory compound for sensitive skin care: in vitro and clinical assessment. Journal of cosmetic dermatology, 7(2), pp.112-119.
- Federici, A., Federici, G. and Milani, M., 2012. An urea, arginine and carnosine based cream (Ureadin Rx Db ISDIN) shows greater efficacy in the treatment of severe xerosis of the feet in Type 2 diabetic patients in comparison with glycerol-based emollient cream. A randomized, assessor-blinded, controlled trial. BMC dermatology, 12(1), p.16.