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. 2022 Jul 12:10:e13701.
doi: 10.7717/peerj.13701. eCollection 2022.

Characterization of human tear proteome reveals differentially abundance proteins in thyroid-associated ophthalmopathy

Xiaoqing Zhou  1 , Ruili Wei  1 , Rui Wang  2
Affiliations

Characterization of human tear proteome reveals differentially abundance proteins in thyroid-associated ophthalmopathy

Xiaoqing Zhou et al. PeerJ. .

Abstract

Background: Thyroid-associated ophthalmopathy (TAO) is a common orbital inflammatory disease, but the abnormal expression of proteins in tears of TAO patients has not been systematically studied. The purpose of this study is to compare and analyze the total tear protein profile of TAO patients and to provide protein cues for TAO pathogenesis.

Methods: Tear samples were isolated from 30 TAO patients with obvious ocular surface damage and 30 healthy control subjects. Tear samples from 30 individuals were mixed and divided into three sample pools. Easy nano-scale LC-MS/MS based on labeling-free quantitative technology was utilized to profile tear proteome.

Results: Here, electrospray ionization mass spectra and SDS-PAGE results confirmed the good parallelisms among samples. A total of 313 proteins were obtained from six tear pools, among them, 103 differential abundance proteins (DAPs) were identified, including 99 up-regulated DAPs (including APOA1, HV103, IGH, and Transferrin variant) and four down-regulated DAPs (including FABA, VCC1, NUCB2, and E-cadherin) in the TAO group compared with the control group. GO analysis showed that up-regulated DAPs were mainly enriched in lipid metabolism and platelet molecular function, and down-regulated DAPs were involved in binding, cell junction, and cellular process. KEGG results indicated that DAPs were involved in 117 kinds of signal transduction pathways, among which the immune-related pathway of complement and coagulation cascades had the greatest relevance.

Conclusion: In conclusion, label-free LC-MS/MS is an effective strategy for profiling tear proteins component. Our study provides proteins and pathways altered in TAO and provides protein cues for further study on the precise mechanism of TAO pathogenesis.

Keywords: Complement and coagulation cascades; Hyroid-associated ophthalmopathy; Label-free LC-MS/MS; Proteomics analysis; Tears.

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Conflict of interest statement

The authors declare that they have no competing interests.

Figures

Figure 1
Figure 1. Sample quality control and parallel testing.
Gel image of SDS-PAGE.
Figure 2
Figure 2. Base peak of ESI mass spectra of tear proteins of the TAO group and the HC group.
Figure 3
Figure 3. Overall of protein profiles.
(A) Venn diagram of the number of identified proteins in TAO group and HC group. (B) Volcanic map of DAPs between TAO group and HC group. (C) Histogram of protein abundance of top 10 up-regulated DAPs and four down-regulated DAPs detected by LC-MS/MS.
Figure 4
Figure 4. Go analysis of DAPs.
(A) Top 20 of Go enrichment of 99 up-regulated DAPs. Red to green indicates that the GO entry has increased in significance. The size of the circle indicates the number of proteins. (B) GO analysis of four down-regulated DAPs. Red represents cellular components (CC), yellow represents molecular functions (MF), and blue represents biological processes (BP).
Figure 5
Figure 5. KEGG analysis of all DAPs.
The vertical axis represents the name of the pathway, and the horizontal axis represents the number of proteins clustered in pathway.
Figure 6
Figure 6. Complement and coagulation cascades pathway.
DAPs were shown up in bright green.
See this image and copyright information in PMC

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