Metabolic profiling of serum from dogs with pituitary-dependent hyperadrenocorticism

Analytical validation of an automated assay to measure calprotectin (S100A8/A9) in dog saliva and serum and changes in canine leishmaniasis, pyometra and hyperadrenocorticism

BACKGROUND

Calprotectin (S100A8/A9) is a protein related to innate immunity that is considered a biomarker of inflammation. Currently, there is a commercially available automated assay for the measurement of calprotectin concentration (Bühlmann fCal Turbo® assay), which has been previously validated for saliva and serum of swine and for saliva of horses, and in the canine species it has been validated for use with fecal samples, but it has not been previously validated in canine saliva or serum. Thus, the aim of this study was to perform an analytical validation of an automated assay for the measurement of calprotectin in the saliva and serum of dogs. In addition, changes in this protein in saliva and serum of three diseases with different pathogenic mechanisms - leishmaniasis, pyometra and hyperadrenocorticism - were evaluated. Finally, in these diseases, the correlation of salivary and serum calprotectin with the serum levels of three acute phase proteins (APPs), including C-reactive protein (CRP), haptoglobin (Hp) and ferritin, was also assessed.

RESULTS

The analytical validation results showed that the assay was precise (coefficients of variation < 15% in all cases), accurate (the dilutional parallelism for serum and salivary calprotectin showed observed-to-expected ratios with a mean of 96.9% and 97.2%, respectively), and presented a limit of detection of 0.038 mg/L. When this assay was applied to the different diseases, a significant increase in the concentration of salivary calprotectin in dogs with leishmaniasis (p = 0.0002) and in those with pyometra (p = 0.002), compared to healthy ones, was observed, whereas no significant differences were found in serum. Furthermore, a significant positive moderate correlation was obtained between salivary calprotectin and serum CRP (r = 0.5; p = 0.001) and haptoglobin (r = 0.5; p = 0.002), and between calprotectin and CRP (r = 0.67; p < 0.001) in serum.

CONCLUSIONS

Calprotectin (S100A8/A9) can be measured in dog saliva and serum samples by the automated method validated in this study, and when measured in saliva it could be used as a potential biomarker of inflammation and immune activation in the dog.

Effect of leukoreduction on the omics phenotypes of canine packed red blood cells during refrigerated storage

BACKGROUND

Red blood cell (RBC) storage promotes biochemical and morphological alterations, collectively referred to as storage lesions (SLs). Studies in humans have identified leukoreduction (LR) as a critical processing step that mitigates SLs. To date no study has evaluated the impact of LR on metabolic SLs in canine blood units using omics technologies.

OBJECTIVE

Compare the lipid and metabolic profiles of canine packed RBC (pRBC) units as a function of LR in fresh and stored refrigerated (up to 42 days) units.

ANIMALS

Packed RBC units were obtained from 8 donor dogs enrolled at 2 different Italian veterinary blood banks.

STUDY DESIGN AND METHODS

Observational study. A volume of 450 mL of whole blood was collected using Citrate-Phosphate-Dextrose-Saline-Adenine-Glucose-Mannitol (CPD-SAGM) transfusion bags with a LR filter to produce 2 pRBC units for each donor, without (nLR-pRBC) and with (LR-pRBC) LR. Units were stored in the blood bank at 4 ± 2°C. Sterile weekly samples were obtained from each unit for omics analyses.

RESULTS

A significant effect of LR on fresh and stored RBC metabolic phenotypes was observed. The nLR-pRBC were characterized by higher concentrations of free short and medium-chain fatty acids, carboxylic acids (pyruvate, lactate), and amino acids (arginine, cystine). The LR-pRBC had higher concentrations of glycolytic metabolites, high energy phosphate compounds (adenosine triphosphate [ATP]), and antioxidant metabolites (pentose phosphate, total glutathione).

CONCLUSION AND CLINICAL IMPORTANCE

Leukoreduction decreases the metabolic SLs of canine pRBC by preserving energy metabolism and preventing oxidative lesions.

Metabolomic Abnormalities in Serum from Untreated and Treated Dogs with Hyper- and Hypoadrenocorticism

The adrenal glands play a major role in metabolic processes, and both excess and insufficient serum cortisol concentrations can lead to serious metabolic consequences. Hyper- and hypoadrenocorticism represent a diagnostic and therapeutic challenge. Serum samples from dogs with untreated hyperadrenocorticism (n = 27), hyperadrenocorticism undergoing treatment (n = 28), as well as with untreated (n = 35) and treated hypoadrenocorticism (n = 23) were analyzed and compared to apparently healthy dogs (n = 40). A validated targeted proton nuclear magnetic resonance (¹H NMR) platform was used to quantify 123 parameters. Principal component analysis separated the untreated endocrinopathies. The serum samples of dogs with untreated endocrinopathies showed various metabolic abnormalities with often contrasting results particularly in serum concentrations of fatty acids, and high- and low-density lipoproteins and their constituents, which were predominantly increased in hyperadrenocorticism and decreased in hypoadrenocorticism, while amino acid concentrations changed in various directions. Many observed serum metabolic abnormalities tended to normalize with medical treatment, but normalization was incomplete when compared to levels in apparently healthy dogs. Application of machine learning models based on the metabolomics data showed good classification, with misclassifications primarily observed in treated groups. Characterization of metabolic changes enhances our understanding of these endocrinopathies. Further assessment of the recognized incomplete reversal of metabolic alterations during medical treatment may improve disease management.