Ectoine in the Treatment of Irritations and Inflammations of the Eye Surface

Abstract

The ocular surface is facing various unspecific stress factors resulting in irritation and inflammation of the epithelia, causing discomfort to the patients. Ectoine is a bacteria-derived extremolyte with the ability to protect proteins and biological membranes from damage caused by extreme environmental conditions like heat, UV-light, high osmolarity, or dryness. Evidence from preclinical and clinical studies attest its effectiveness in treating several epithelium-associated inflammatory diseases, including the eye surface. In this review, we analysed 16 recent clinical trials investigating ectoine eye drops in patients with allergic conjunctivitis or with other unspecific ocular inflammations caused by e.g. ophthalmic surgery. Findings from these studies were reviewed in context with other published work on ectoine. In summary, patients with irritations and unspecific inflammations of the ocular surface have been treated successfully with ectoine-containing eye drops. In these patients, significant improvement was observed in ocular symptoms of allergic rhinoconjunctivitis, postoperative secondary dry eye syndrome, or ocular reepithelisation after surgery. Using ectoine as an add-on therapy to antihistamines, in allergy patients accelerated symptom relief by days, and its use as an add-on to antibiotics resulted in faster wound closure. Ectoine is a natural substance with an excellent tolerability and safety profile thus representing a helpful alternative for patients with inflammatory irritation of the ocular surface, who wish to avoid local reactions and side effects associated with pharmacological therapies or wish to increase the efficacy of standard treatment regimen.

Figure 1

Flow chart of the literature selection process.

Figure 2

Ectoine's mechanism of action. (a) Influence on water molecules and proteins: in the presence of ectoine, the water structure is altered and more compact, and proteins are stabilised. (b) Molecular model explaining the effect of ectoine on the tear fluid lipid layer (picture taken from Dwivedi et al.) [19]. (c) Model of effects of ectoine on cell membranes (lipid bilayers) without external stress. (d) Protective effect of ectoine against external damage (e.g., allergens, UV-light, and physical damage): the ectoine water interaction results in the protection of cell membranes (lipid bilayers), thus leading to reduced release of stress mediators.