Abstract
The aim of this study was to investigate the proteins found in tear film of healthy domestic cats. Schirmer tear test strips were used to collect tear samples of twelve healthy cats, which were mixed, centrifuged, and placed in a single 1.5 mL microtube that was frozen at −20°C, until analysis by two-dimensional polyacrylamide gel and mass spectrometry associated with high-performance liquid chromatography. The resulting spectra were analyzed and compared with the Swiss-Prot search tool. Forty peptides were detected in the analyzed protein fragments of 90 spots, with 16 proteins identified. Of these, the authors confirmed what has been already found in other studies: lactotransferrin, serum albumin, allergenic lipocalins, and neutrophil gelatinase-associated lipocalin. Others were considered novel in tear film samples of all species: cyclin-dependent protein kinase, serine/arginine repetitive matrix protein, apelin receptor, secretory protein related to C1q/TNF, Wee1, α-1,4 glucan phosphorylase, and WD repeat domain 1. The network was divided into 11 clusters, and a biological function was assigned. Most of the proteins have functions in the defense and maintenance of feline ocular surface homeostasis. Serum albumin is a bottleneck protein, with a high betweenness value. This paper is a pioneer in reporting, in-depth, the tear film proteome of domestic cats.
Highlights
Tear film (TF) is a complex and viscous trilaminar fluid composed mainly of proteins, lipids, electrolytes, and water [1], with a protective function for the ocular surface. is protection is based on the presence of proteins in the TF, which participate in the modulation of healing processes and in direct defense against pathogens [2].Changes in the expression of tear proteins can be associated with systemic and ophthalmic diseases. us, its evaluation has been widely explored in human medicine as a noninvasive tool to discover molecular biomarkers for diagnosis and prognosis of several diseases [3, 4]
Is study included 12 mixed-breed domestic cats (Felis catus), of both genders, between 11 and 12 months of age, living in a controlled environment. e selected cats were previously castrated, dewormed, and immunized against the main infectious diseases. ey were certified as healthy by physical examination, had complete blood count (CBC) performed, and the concentrations of alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma glutamyl transferase (GGT), bilirubins, urea, and creatinine were within normal range. e cats were negative for Toxoplasma gondii, FIV/ FeLV, and feline coronavirus antibodies
Most of the proteins identified have important functions in the defense and maintenance of homeostasis of the feline ocular surface. e relative abundance of all proteins found in this study promotes the first dispersion pattern, which can be considered a signature of the behavior and distribution of proteins in healthy cats
Summary
Tear film (TF) is a complex and viscous trilaminar fluid composed mainly of proteins, lipids, electrolytes, and water [1], with a protective function for the ocular surface. is protection is based on the presence of proteins in the TF, which participate in the modulation of healing processes and in direct defense against pathogens [2].Changes in the expression of tear proteins can be associated with systemic and ophthalmic diseases. us, its evaluation has been widely explored in human medicine as a noninvasive tool to discover molecular biomarkers for diagnosis and prognosis of several diseases [3, 4]. Changes in the expression of tear proteins can be associated with systemic and ophthalmic diseases. E study of microcomponents such as proteins and their properties can be the first step for future studies of disease biomarkers in this species [1, 9]. It is relevant to investigate the domestic feline TF proteome since knowledge of the proteome profile in cats’ tears is the first step toward future studies of possible disease biomarkers of feline ophthalmic diseases, as well as systemic diseases. Us, the aim of this study was to describe the proteins found in the tear film of healthy domestic cats, which was possible to be obtained through the methodology used It is relevant to investigate the domestic feline TF proteome since knowledge of the proteome profile in cats’ tears is the first step toward future studies of possible disease biomarkers of feline ophthalmic diseases, as well as systemic diseases. us, the aim of this study was to describe the proteins found in the tear film of healthy domestic cats, which was possible to be obtained through the methodology used
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