Topical Application of Deglycating Enzymes as an Alternative Non-Invasive Treatment for Presbyopia.

Presbyopia is an age-related vision disorder that is a global public health problem. Up to 85% of people aged ≥40 years develop presbyopia. In 2015, 1.8 billion people globally had presbyopia. Of those with significant near vision disabilities due to uncorrected presbyopia, 94% live in developing countries. Presbyopia is undercorrected in many countries, with reading glasses available for only 6-45% of patients living in developing countries. The high prevalence of uncorrected presbyopia in these parts of the world is due to the lack of adequate diagnosis and affordable treatment. The formation of advanced glycation end products (AGEs) is a non-enzymatic process known as the Maillard reaction. The accumulation of AGEs in the lens contributes to lens aging (leading to presbyopia and cataract formation). Non-enzymatic lens protein glycation induces the gradual accumulation of AGEs in aging lenses. AGE-reducing compounds may be effective at preventing and treating AGE-related processes. Fructosyl-amino acid oxidase (FAOD) is active on both fructosyl lysine and fructosyl valine. As the crosslinks encountered in presbyopia are mainly non-disulfide bridges, and based on the positive results of deglycating enzymes in cataracts (another disease caused by glycation of lens proteins), we studied the ex vivo effects of topical FAOD treatment on the power of human lenses as a new potential non-invasive treatment for presbyopia. This study demonstrated that topical FAOD treatment resulted in an increase in lens power, which is approximately equivalent to the correction obtained by most reading glasses. The best results were obtained for the newer lenses. Simultaneously, a decrease in lens opacity was observed, which improved lens quality. We also demonstrated that topical FAOD treatment results in a breakdown of AGEs, as evidenced by gel permeation chromatography and a marked reduction in autofluorescence. This study demonstrated the therapeutic potential of topical FAOD treatment in presbyopia.

Enzymatic Deglycation of Damaged Skin by Means of Combined Treatment of Fructosamine-3-Kinase and Fructosyl-Amino Acid Oxidase.

The consensus in aging is that inflammation, cellular senescence, free radicals, and epigenetics are contributing factors. Skin glycation through advanced glycation end products (AGEs) has a crucial role in aging. Additionally, it has been suggested that their presence in scars leads to elasticity loss. This manuscript reports fructosamine-3-kinase (FN3K) and fructosyl-amino acid oxidase (FAOD) in counteracting skin glycation by AGEs. Skin specimens were obtained (n = 19) and incubated with glycolaldehyde (GA) for AGE induction. FN3K and FAOD were used as monotherapy or combination therapy. Negative and positive controls were treated with phosphate-buffered saline and aminoguanidine, respectively. Autofluorescence (AF) was used to measure deglycation. An excised hypertrophic scar tissue (HTS) (n = 1) was treated. Changes in chemical bonds and elasticity were evaluated using mid-infrared spectroscopy (MIR) and skin elongation, respectively. Specimens treated with FN3K and FAOD in monotherapy achieved an average decrease of 31% and 33% in AF values, respectively. When treatments were combined, a decrease of 43% was achieved. The positive control decreased by 28%, whilst the negative control showed no difference. Elongation testing of HTS showed a significant elasticity improvement after FN3K treatment. ATR-IR spectra demonstrated differences in chemical bounds pre- versus post-treatment. FN3K and FAOD can achieve deglycation and the effects are most optimal when combined in one treatment.