Serum proteome profiles in cats with chronic enteropathies

Abstract

Background: Serum protein biomarkers are used to diagnose, monitor treatment response, and to differentiate various forms of chronic enteropathies (CE) in humans. The utility of liquid biopsy proteomic approaches has not been examined in cats.

Hypothesis/objectives: To explore the serum proteome in cats to identify markers differentiating healthy cats from cats with CE.

Animals: Ten cats with CE with signs of gastrointestinal disease of at least 3 weeks duration, and biopsy-confirmed diagnoses, with or without treatment and 19 healthy cats were included.

Methods: Cross-sectional, multicenter, exploratory study with cases recruited from 3 veterinary hospitals between May 2019 and November 2020. Serum samples were analyzed and evaluated using mass spectrometry-based proteomic techniques.

Results: Twenty-six proteins were significantly (P < .02, ≥5-fold change in abundance) differentially expressed between cats with CE and controls. Thrombospondin-1 (THBS1) was identified with >50-fold increase in abundance in cats with CE (P < 0.001) compared to healthy cats.

Conclusions and clinical importance: Damage to the gut lining released marker proteins of chronic inflammation that were detectable in serum samples of cats. This early-stage exploratory study strongly supports THBS1 as a candidate biomarker for chronic inflammatory enteropathy in cats.

Keywords: alimentary small cell lymphoma; biomarkers; chronic enteropathies; low-grade alimentary lymphoma; proteins; proteomics.

FIGURE 1

Volcano plot showing abundance graph of log 2‐fold change CE in reference to controls (CE/C) with statistical significance (Fisher's exact test) set to P < .02. X axis represents upregulated (>0) and downregulated protein (<0) abundance of cats with CE in reference to controls.

FIGURE 2

(A) Molecular functions of ≥|2| fold increased protein in abundance and significance in cats with chronic enteropathies (CE) compared to controls. (B) Biological process of ≥|2| fold increased protein in abundance and significance in cats with CE compared to controls. (C) Differences in pathways between cats with CE and controls by significance and ≥|2| fold change with gene analysis.

FIGURE 3

Protein‐protein interaction network for differentially expressed proteins between cats with chronic enteropathies and controls shows 2 distinct clusters (red and green) representing the involvement of the (a) extracellular matrix (ECM) and (b) altered coagulation, lipid regulation in the inflammatory state. ACTB, actin; APOA1, apolipoprotein A1; APOB, apolipoprotein B; APOC3, apolipoprotein C3; APOE, apolipoprotein E; CLU, clusterin; CPAMD8, C3 and PZP‐like alpha‐2‐macroglobulin domain containing protein 8; F5, coagulation factor V; F9, coagulation factor IX; FGB, fibrinogen beta chain; FN1, fibronectin; GSN, gelsolin; HBB, hemoglobin subunit beta; HPX, hemopexin; ITIH2, inter alpha trypsin inhibitor heavy chain H2; ITIH3, inter alpha trypsin inhibitor heavy chain H3; LCAT, phosphatidylcholine‐sterol acyltransferase; LCP1, plastin 2; PFN1, profilin 1; PON1, serum paraoxonase/arylesterase 1; SERPINC1, antithrombin‐III; SERPIND1, heparin cofactor 2; SERPINF2, alpha‐2‐antiplasmin; TAGLN2, transgelin‐2; THBS1, thrombospondin 1; TPM4, tropomyosin alpha‐4 chain; TTR, transthyretin; VCL, vinculin.

FIGURE 4

A dot plot showing the relative abundance based on spectral count of THBS1 in individual control and cats with chronic enteropathies (CE). The median is illustrated by the black line, median for cats with CE is 4.5 (range, 0‐21) and median for controls is 0 (range, 0‐1).