<abstract xmlns="http://www.w3.org/1999/xhtml">
<sec id="j_jvetres-2022-0053_s_005"><h3>Introduction</h3>
<p>Diabetic retinopathy (DR) is the leading cause of blindness in human and animal patients. Early detection and treatment of the disease are important and can be facilitated by proteomic approaches providing biomarkers.</p>
</sec>
<sec id="j_jvetres-2022-0053_s_006"><h3>Material and Methods</h3>
<p>Tear films were collected on Schirmer strips from 32 canine patients (12 diabetic dogs without changes in the retina, 8 diabetic dogs with signs of DR, and 12 control dogs). Two-dimensional electrophoresis was used to separate tear film proteins prior to their identification with matrix-assisted laser desorption/ionisation–tandem time-of-flight mass spectrometry and interrogation of protein function databases to find matches.</p>
</sec>
<sec id="j_jvetres-2022-0053_s_007"><h3>Results</h3>
<p>Five significantly differentially expressed proteins were identified; of those, one was downregulated (2ʹ-5ʹ-oligoadenylate synthase 3) and four were upregulated in the tear film of two diabetic groups (Ras-related protein RAB-13; aldo-keto-reductase family 1 member C3; 28S ribosomal protein S31, mitochondrial; and 60S ribosomal protein L5). The differentially expressed proteins identified in the tear film were involved in signalling pathways associated with impaired protein clearance, persistent inflammation and oxidative stress.</p>
</sec>
<sec id="j_jvetres-2022-0053_s_008"><h3>Conclusion</h3>
<p>The results of our study confirm that the pathological process in the retina in the course of diabetes mellitus causes changes in the tear film proteome.</p>
</sec>
</abstract>

Introduction
Diabetic retinopathy (DR) is the leading cause of blindness in human and animal patients. Early detection and treatment of the disease are important and can be facilitated by proteomic approaches providing biomarkers.

Material and Methods
Tear films were collected on Schirmer strips from 32 canine patients (12 diabetic dogs without changes in the retina, 8 diabetic dogs with signs of DR, and 12 control dogs). Two-dimensional electrophoresis was used to separate tear film proteins prior to their identification with matrix-assisted laser desorption/ionisation–tandem time-of-flight mass spectrometry and interrogation of protein function databases to find matches.

Results
Five significantly differentially expressed proteins were identified; of those, one was downregulated (2ʹ-5ʹ-oligoadenylate synthase 3) and four were upregulated in the tear film of two diabetic groups (Ras-related protein RAB-13; aldo-keto-reductase family 1 member C3; 28S ribosomal protein S31, mitochondrial; and 60S ribosomal protein L5). The differentially expressed proteins identified in the tear film were involved in signalling pathways associated with impaired protein clearance, persistent inflammation and oxidative stress.

Conclusion
The results of our study confirm that the pathological process in the retina in the course of diabetes mellitus causes changes in the tear film proteome.

Proteomic analysis of tear film in canine diabetic patients with and without retinopathy

Journal of Veterinary Research

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Introduction
Diabetic retinopathy (DR) is the leading cause of blindness in human and animal patients. Early detection and treatment of the disease are...

ID	Protein	Accession number (UniProtKB)	Score	Match	MW (kDa)*	pI*	Modif.	Seq. cov. (%)	Rt** C : D	Rt** C : D ret.	P-value
1	Ras-Rab-related 13 protein	F1PTE3	79	6	22881	9.36	Carb, (M) Ox	24	0.655	0.455	0.048

2	Aldo-family keto 1 member reductase C3	Q5R7C9	70	9	37224	7.13	Carb	18	0.793	0.015	0.015

3	28S ribosomal protein S31, mitochondrial	B0BN56	111	8	44220	8.46	Carb, Ox (M)	14	0.189	0.502	0.032

4	2synthase ′-5′-oligoadenylate 3	Q8VI93	120	11	127907	8.99	Carb, (M) Ox	8	2.709	1.741	0.030

5	60protein S ribosomal L5	P46777	81	20	34568	9.78	Carb, (M) Ox	42	0.074	0.128	0.001

Variable	Healthy subject n = 12	With diabetic retinopathy n = 8	Diabetic without retinopathy n = 12
Age, Y
Mean (±SD)	10.8 ± 1.8	10.3 ± 2.8	11.4 ± 2.1
Range	8–13	7–16	8–12

Sex
Male	7	3	4
Female	5	5	8

Weight, kg
Mean (±SD)	23.1 ± 7.7	13.9 ± 8.6	14.4 ± 5.3
Range	10–37	5.4–38	6.3–21

Duration of diabetes, y
Mean (±SD)	0	1.2 ± 0.6	2.4 ± 0.2
Duration	0	0.5–2	1–4

Blood glucose, mmol/L
Mean (±SD)	5.9 ± 0.2	17.8 ± 6	18.3 ± 2.3
Range	5.6–6.2	8.3–29.7	9.3–22.3

Cataract	0	0	0

Proteomic analysis of tear film in canine diabetic patients with and without retinopathy

Published Online: Nov 07, 2022

Page range: 629 - 635

Received: Jun 02, 2022

Accepted: Oct 24, 2022

DOI: https://doi.org/10.2478/jvetres-2022-0053

Keywords
proteomics, tear film, protein, animal model, diabetes mellitus

© 2022 D. Winiarczyk et al. published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Fig. 1

Fig. 2

Significantly differentially expressed proteins (P ≤ 0.05) in diabetic dogs identified by matrix-assisted laser desorption/ionisation–tandem time-of-flight mass spectrometry

Clinical characteristics of the study subjects

Proteomic analysis of tear film in canine diabetic patients with and without retinopathy

Published Online: Nov 07, 2022

Page range: 629 - 635

Received: Jun 02, 2022

Accepted: Oct 24, 2022

DOI: https://doi.org/10.2478/jvetres-2022-0053

Keywordsproteomics, tear film, protein, animal model, diabetes mellitus

© 2022 D. Winiarczyk et al. published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Fig. 1

Fig. 2

Significantly differentially expressed proteins (P ≤ 0.05) in diabetic dogs identified by matrix-assisted laser desorption/ionisation–tandem time-of-flight mass spectrometry

Clinical characteristics of the study subjects

Keywords
proteomics, tear film, protein, animal model, diabetes mellitus