The ocular surface is in constant interaction with the environment and with numerous pathogens. Therefore, complex mechanisms such as a stable tear film and local immune defense mechanisms are required to protect the eye. This study describes the detection, characterization, and putative role of surfactant protein G (SP-G/SFTA2) with respect to wound healing and surface activity. Bioinformatic, biochemical, and immunological methods were combined to elucidate the role of SP-G in tear film. The results show the presence of SP-G in ocular surface tissues and tear film (TF). Increased expression of SP-G was demonstrated in TF of patients with dry eye disease (DED). Addition of recombinant SP-G in combination with lipids led to an accelerated wound healing of human corneal cells as well as to a reduction of TF surface tension. Molecular modeling of TF suggest that SP-G may regulate tear film surface tension and improve its stability through specific interactions with lipids components of the tear film. In conclusion, SP-G is an ocular surface protein with putative wound healing properties that can also reduce the surface tension of the tear film.

Department of Physical and Macromolecular Chemistry Faculty of Science Charles University 128 40 Prague Czech Republic

Faculty of Chemistry Jagiellonian University 30387 Krakow Poland

Institute of Functional and Clinical Anatomy Friedrich Alexander Universität Erlangen Nuremberg Universitätsstr 19 91054 Erlangen Germany

J Heyrovský Institute of Physical Chemistry Czech Academy of Sciences 182 00 Prague Czech Republic

Ophthalmology Private Practice 17 81034 Nuremberg Germany

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