Clinicopathological and Fecal Proteome Evaluations in 16 Dogs Presenting Chronic Diarrhea Associated with Lymphangiectasia

Abstract

Canine intestinal lymphangiectasia (IL) is a condition characterized by variably severe gastrointestinal signs, frequently associated with laboratory abnormalities; the research for markers allowing a better understanding of the severity degree and/or obtaining an early diagnosis and/or monitoring is continuously progressing. In the present study, we investigated possible new diagnostic/follow-up markers in IL dogs, namely, serum C-reactive protein, serum bacterial lipopolysaccharide, serum cleaved cytokeratin 18, serum citrulline, and zonulin (in both serum and feces). A fecal proteomic study looking for possible confirmation and/or new marker candidates was also performed. All markers in both substrates, with the exception of serum citrulline, significantly differed between diseased and control dogs. Fecal proteomics allowed the retrieval of three proteins in IL dogs (Fc fragment of IgG-binding protein; transthyretin; proproteinase E) that were not previously found in clinically healthy subjects. Although further studies are needed, C-reactive protein, bacterial lipopolysaccharide, cleaved cytokeratin 18, and zonulin (in both serum and feces) resulted as promising markers for canine IL; similarly, fecal proteomics represents a road worthy of being pursued in the search for candidate biomarkers.

Evaluation of the Fecal Proteome in Healthy and Diseased Cheetahs (Acinonyx jubatus) Suffering from Gastrointestinal Disorders

“…In addition to the aforementioned spots, the proteomic maps of the healthy and diseased cheetahs were compared with the proteomic maps from healthy and diseased dogs’ feces already present in the literature [ 7 , 9 ]. The spots named H, H1, H3, G, G1, G2, G3 and G4 (evidenced by red circles in Figure 1 ) were consistently present in all of the stool samples examined and were assumed to correspond, as previously reported [ 7 , 9 ], to: Chymotrypsin-C-like (spot H), Elastase-3B (spot H1), Immunoglobulin kappa light chain (spot H3), Immunoglobulin λ − 1 light chain (spots G and G1) and Immunoglobulin λ-light chain VLJ (spots G2, G3 and G4).…”

“…Albumin (and relative isoforms) was previously found in both healthy dogs and cats [ 7 ] and was interpreted as the result of the physiological mucosal cellular turnover. In the case of DC, considering that albumin was found only in this group and not in the healthy one, it is possible to hypothesize that its presence may be due to the damage associated with GI disturbances, as is also assumed for the dogs suffering from intestinal lymphangiectasia [ 9 ].…”

“…Type II collagen is fundamental for the normal embryonic development of the skeleton and for the ability of cartilage to resist compressive forces. Spots HC2, HC3 and HC5 correspond to the transthyretin isoform, a protein whose main role is to transport, in plasma, retinol and thyroid hormones and is synthetized in the liver, brain and pancreas [ 9 , 12 ]. This protein is a 56-kDa protein composed of four identical subunits, and it contains a free cysteine thiol group residue prone to oxidation that gives rise to transthyretin isoforms.…”

“…The modifications of this cysteine residue may reflect oxidative stress and are potentially related to transthyretin amyloidosis and Alzheimer’s disease [ 13 , 14 ]. Indeed, it is interesting that the amyloidogenic mutations of such protein have been associated with amyloids deposits (transthyretin amyloidosis), possibly correlated with the progressive damage of the autonomic nervous system, which may be in turn be associated with reduced GI motility [ 9 , 15 ]. Transthyretin is also considered a negative acute phase protein, as it commonly decreases in human neurological disorders, notwithstanding the fact that it was found to be upregulated, in a corticosteroid-related way, in dogs suffering from cervical spondylomyelopathy [ 16 ] but was also found to be decreased in dogs with pyometra [ 17 ].…”

“…The protocol for fecal protein extraction and subsequent two-dimensional electrophoresis (2DE) has been described in previous works [ 7 , 8 , 9 ]. Briefly, two grams of feces from each healthy (HC) and diseased (DC) animal were weighed and pooled together, amounting to a total of 22.0 g of feces from both groups.…”