Changes in the Salivary Proteome Associated With Canine Pyometra

Characterization of the plasma proteome from healthy adult dogs

Introduction

Bloodwork is a widely used diagnostic tool in veterinary medicine, as diagnosis and therapeutic interventions often rely on blood biomarkers. However, biomarkers available in veterinary medicine often lack sensitivity or specificity. Mass spectrometry-based proteomics technology has been extensively used in the analysis of biological fluids. It offers excellent potential for a more comprehensive characterization of the plasma proteome in veterinary medicine.

Methods

In this study, we aimed to identify and quantify plasma proteins in a cohort of healthy dogs and compare two techniques for depleting high-abundance plasma proteins to enable the detection of lower-abundance proteins via label-free quantification liquid chromatography-mass spectrometry. We utilized surplus lithium-heparin plasma from 30 healthy dogs, subdivided into five groups of pooled plasma from 6 randomly selected individuals each. Firstly, we used a commercial kit to deplete high-abundance plasma proteins. Secondly, we employed an in-house method to remove albumin using Blue-Sepharose.

Results and discussion

Among all the samples, some of the most abundant proteins identified were apolipoprotein A and B, albumin, alpha-2-macroglobulin, fibrinogen beta chain, fibronectin, complement C3, serotransferrin, and coagulation factor V. However, neither of the depletion techniques achieved significant depletion of highly abundant proteins. Despite this limitation, we could detect and quantify many clinically relevant proteins. Determining the healthy canine proteome is a crucial first step in establishing a reference proteome for canine plasma. After enrichment, this reference proteome can later be utilized to identify protein markers associated with different diseases, thereby contributing to the diagnosis and prognosis of various pathologies.

Mass spectrometry-based proteomics profiling of dogs with and without oral diseases: a systematic review

BACKGROUND

Understanding the distinct proteomics profiles in dogs' oral biofluids enhances diagnostic and therapeutic insights for canine oral diseases, fostering cross-species translational research in dentistry and medicine. This study aimed to conduct a systematic review to investigate the similarities and differences between the oral biofluids' proteomics profile of dogs with and without oral diseases.

METHODS

PubMed, Web of Science, and Scopus were searched with no restrictions on publication language or year to address the following focused question: "What is the proteome signature of healthy versus diseased (oral) dogs' biofluids?" Gene Ontology enrichment and the Kyoto Encyclopedia of Genes and Genomes pathway analyses of the most abundant proteins were performed. Moreover, protein-protein interaction analysis was conducted. The risk of bias (RoB) among the included studies was assessed using the Joanna Briggs Institute (JBI) Critical Appraisal Checklist for Studies Reporting Prevalence Data.

RESULTS

In healthy dogs, the proteomic analysis identified 5,451 proteins, with 137 being the most abundant, predominantly associated with 'innate immune response'. Dogs with oral diseases displayed 6,470 proteins, with distinct associations: 'defense response to bacterium' (periodontal diseases), 'negative regulation of transcription' (dental calculus), and 'positive regulation of transcription' (oral tumors). Clustering revealed significant protein clusters in each case, emphasizing the diverse molecular profiles in health and oral diseases. Only six studies were provided to the JBI tool, as they encompassed case-control evaluations that compared healthy dogs to dogs with oral disease(s). All included studies were found to have low RoB (high quality).

CONCLUSION

Significant differences in the proteomics profiles of oral biofluids between dogs with and without oral diseases were found. The synergy of animal proteomics and bioinformatics offers a promising avenue for cross-species research, despite persistent challenges in result validation.

Defining sepsis in small animals

OBJECTIVE

To discuss the definitions of sepsis in human and veterinary medicine.

DESIGN

International, multicenter position statement on the need for consensus definitions of sepsis in veterinary medicine.

SETTING

Veterinary private practice and university teaching hospitals.

ANIMALS

Dogs and cats.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Sepsis is a life-threatening condition associated with the body's response to an infection. In human medicine, sepsis has been defined by consensus on 3 occasions, most recently in 2016. In veterinary medicine, there is little uniformity in how sepsis is defined and no consensus on how to identify it clinically. Most publications rely on modified criteria derived from the 1991 and 2001 human consensus definitions. There is a divergence between the human and veterinary descriptions of sepsis and no consensus on how to diagnose the syndrome. This impedes research, hampers the translation of pathophysiology insights to the clinic, and limits our abilities to optimize patient care. It may be time to formally define sepsis in veterinary medicine to help the field move forward. In this narrative review, we present a synopsis of prior attempts to define sepsis in human and veterinary medicine, discuss developments in our understanding, and highlight some criticisms and shortcomings of existing schemes.

CONCLUSIONS

This review is intended to serve as the foundation of current efforts to establish a consensus definition for sepsis in small animals and ultimately generate evidence-based criteria for its recognition in veterinary clinical practice.

Comparative Serum Proteome Profiling of Canine Benign Prostatic Hyperplasia before and after Castration

BPH is the most prevalent prostatic condition in aging dogs. Nevertheless, clinical diagnosis and management remain inconsistent. This study employed in-solution digestion coupled with nano-liquid chromatography tandem mass spectrometry to assess serum proteome profiling of dogs with BPH and those dogs after castration. Male dogs were divided into two groups; control and BPH groups. In the BPH group, each dog was evaluated at two time points: Day 0 (BF subgroup) and Day 30 after castration (AT subgroup). In the BF subgroup, three proteins were significantly upregulated and associated with dihydrotestosterone: solute carrier family 5 member 5, tyrosine-protein kinase, and FRAT regulator of WNT signaling pathway 1. Additionally, the overexpression of polymeric immunoglobulin receptors in the BF subgroup hints at its potential as a novel protein linked to the BPH development process. Conversely, alpha-1-B glycoprotein (A1BG) displayed significant downregulation in the BF subgroup, suggesting A1BG's potential as a predictive protein for canine BPH. Finasteride was associated with increased proteins in the AT subgroup, including apolipoprotein C-I, apolipoprotein E, apolipoprotein A-II, TAO kinase 1, DnaJ homolog subfamily C member 16, PH domain and leucine-rich repeat protein phosphatase 1, neuregulin 1, and pseudopodium enriched atypical kinase 1. In conclusion, this pilot study highlighted alterations in various serum proteins in canine BPH, reflecting different pathological changes occurring in this condition. These proteins could be a source of potential non-invasive biomarkers for diagnosing this disease.

Pyometra in Small Animals 3.0

Pyometra is a common disease in intact bitches and queens and occurs, although less frequently, in most other female pets. In bitches and queens, the illness is generally diagnosed within 4 months after estrus, in middle-aged to older individuals. Complications such as peritonitis, endotoxemia, and systemic inflammatory response syndrome are not uncommon and associated with more severe illness. Ovary-sparing surgical options such as hysterectomy could be considered in individuals with high-risk for detrimental side effects of spaying or without infection of the uterus but has not yet been evaluated for safety in pyometra.

Urinary Proteins of Female Domestic Dog (Canis familiaris) during Ovarian Cycle

The presence and identity of non-volatile chemical signals remain elusive in canines. In this study, we aim to evaluate the urinary proteins of female domestic dogs in the estrus and anestrus phases to evidence the presence of non-volatile chemical signals and to elucidate their identities. We collected urine samples from eight female dogs in the estrus and anestrus phases. A total of 240 proteins were identified in the urine samples using liquid chromatography-mass spectrometry (LC-MS analysis). The comparison of the proteins revealed a significant difference between the estrus and anestrus urine. We identified proteins belonging to the lipocalin family of canines (beta-lactoglobulin-1 and beta-lactoglobulin-2, P33685 and P33686, respectively), one of whose function was the transport of pheromones and which was present only in the estrus urine samples. Moreover, proteins such as Clusterin (CLU), Liver-expressed antimicrobial peptide 2 (LEAP2), and Proenkephalin (PENK) were more abundant in the estrus urine when compared to the anestrus urine. LEAP2 was recently described as a ghrelin receptor antagonist and implicated in regulating food intake and body weight in humans and mice. Proenkephalin, a polypeptide hormone cleaved into opioid peptides, was also recognized as a candidate to determine kidney function. As of yet, none of these have played a role in chemical communication. Clusterin, an extracellular chaperone protecting from protein aggregation implicated in stress-induced cell apoptosis, is a plausible candidate in chemical communication, which is a claim that needs to be ascertained further. Data are available via ProteomeXchange with the identifier PXD040418.

A study on the correlation between intrauterine microbiota and uterine pyogenesis in dogs

Pyometra is a common and high-incidence reproductive system disease in female dogs, and its development involves both hormonal and bacterial factors. Characterization of the endometrial microbiome in healthy dogs and diseased dogs with pyometra remains unclear at present, however. In this study, dogs with pyometra were identified based on the clinical examinations, hematology examinations, vaginal smears and uterine histopathology. The endometrial samples of healthy dogs (n = 30) and diseased dogs (n = 41) were then collected and sequenced by 16S rRNA high-throughput sequencing technology. Dogs with pyometra suffered from inflammation, and their endometrial microbial diversity (ACE and Chao 1 indices) was significantly lower than that of healthy dogs (P < 0.05). The endometrial samples of both groups were enriched in four phyla (Proteobacteria, Firmicutes, Bacteroidetes and Actinobacteria), with a greater abundance of Firmicutes in diseased dogs (P < 0.05). At the genus level, the most prevalent microbes in diseased dogs belonged to Pseudomonas, Escherichia-Shigella, Mycoplasma, Enterococcus, Haemophilus, Vibrio and Ralstonia, with lower levels of Mycoplasma, Enterococcus and Haemophilus in the healthy control. Principal co-ordinates analysis and non-metric multi-dimensional scaling showed that the endometrial microbiome of diseased dogs clustered separately from that of the healthy controls (P < 0.05). In the LDA effect size analysis, 18 members of the endometrial microbiome were screened. Of these, the bacterial species Pseudomonas_aeruginosa and microbes within the genera Mycoplasma, Enterococcus and Haemophilus were found to be enriched in the uteruses of diseased dogs. Furthermore, the Random Forests model further confirmed that Mycoplasma and Haemophilus could be considered as biomarkers of diseased endometrium. In conclusion, this study provided a theoretical basis for the development of probiotic preparation in the future.

Identification of Canine Pyometra-Associated Metabolites Using Untargeted Metabolomics

Canine pyometra frequently occurs in middle-aged to older intact bitches, which seriously affects the life of dogs and brings an economic loss to their owners. Hence, finding a key metabolite is very important for the diagnosis and development of a new safe and effective therapy for the disease. In this study, dogs with pyometra were identified by blood examinations, laboratory analyses and diagnostic imaging, and fifteen endometrium tissues of sick dogs with pyometra and fifteen controls were collected and their metabolites were identified utilizing a UHPLC-qTOF-MS-based untargeted metabolomics approach. The results indicated that the elevated inflammatory cells were observed in dogs with pyometra, suggesting that sick dogs suffered systemic inflammation. In the untargeted metabolic profile, 705 ion features in the positive polarity mode and 414 ion features in the negative polarity mode were obtained in endometrium tissues of sick dogs with pyometra, with a total of 275 differential metabolites (173 in positive and 102 in negative polarity modes). Moreover, the multivariate statistical analyses such as PCA and PLS-DA also showed that the metabolites were significantly different between the two groups. Then, these differential metabolites were subjected to pathway analysis using Metaboanalyst 4.0, and Galactose metabolism, cAMP signaling pathway and Glycerophospholipid metabolism were enriched, proving some insights into the metabolic changes during pyometra. Moreover, the receiver operating characteristic curves further confirmed kynurenic acid was expected to be a candidate biomarker of canine pyometra. In conclusion, this study provided a new idea for exploring early diagnosis methods and a safe and effective therapy for canine pyometra.

Revealing the Changes in Saliva and Serum Proteins of Pigs with Meningitis Caused by Streptococcus Suis: A Proteomic Approach

Meningitis due to Streptococcus suis causes high mortality and morbidity on pig farms and has increasing zoonotic potential worldwide. Saliva proteome analysis would potentially be useful in elucidating pathophysiological changes and mining for new biomarkers to diagnose and monitor S. suis infection. The objective of this study was to investigate the changes in the salivary and serum proteome profile of piglets with meningitis. The LC-MS/MS TMT proteomic approach was used to analyze saliva and serum samples from 20 male piglets: 10 with meningitis and 10 healthy. In saliva, 11 proteins had higher and 10 had lower relative abundance in piglets with meningitis. The proteins with the highest relative abundance were metavinculin (VCL) and desmocollin-2 (DSC2). Adenosine deaminase (ADA) was selected for validation using a spectrophotometric assay and demonstrated excellent performance in the differentiation between healthy and pigs with meningitis due to S. suis. In serum, the most protruding changes occurred for one SERPIN and haptoglobin (HP). In saliva and serum, the highest number of proteins with altered abundance were linked, via the enrichment analysis, with platelet and neutrophil pathways. Overall, meningitis caused by S. suis resulted in specific proteome changes in saliva and serum, reflecting different pathophysiological mechanisms, and marking new potential biomarkers for this infection.

A Proteomic Approach to Elucidate the Changes in Saliva and Serum Proteins of Pigs with Septic and Non-Septic Inflammation

Sepsis is a systemic inflammatory response triggered by an infectious agent and is recognized by the World Health Organization as a global concern, since it is one of the major causes of severe illness in humans and animals. The study of the changes that can occur in saliva and serum in sepsis can contribute to a better understanding of the pathophysiological mechanisms involved in the process and also to discover potential biomarkers that can help in its diagnosis and monitoring. The objective of this study was to characterize the changes that occur in the salivary and serum proteome of pigs with experimentally-induced sepsis. The study included five pigs with sepsis induced by LPS administration and five pigs with non-septic inflammation induced by turpentine for comparative purposes. In saliva, there were eighteen salivary proteins differentially expressed in the sepsis condition and nine in non-septic inflammation. Among these, significant increments in aldolase A and serpin B12 only occurred in the sepsis model. Changes in aldolase A were validated in a larger population of pigs with sepsis due to Streptococcus suis infection. In serum, there were 30 proteins differentially expressed in sepsis group and 26 proteins in the non-septic group, and most of the proteins that changed in both groups were related to non-specific inflammation. In the saliva of the septic animals there were some specific pathways activated, such as the organonitrogen compound metabolic process and lipid transport, whereas, in the serum, one of the main activated pathways was the regulation of protein secretion. Overall, saliva and serum showed different proteome variations in response to septic inflammation and could provide complementary information about the pathophysiological mechanisms occurring in this condition. Additionally, salivary aldolase A could be a potential biomarker of sepsis in pigs that should be confirmed in a larger population.

Analysis of the concentrations of some haematological parameters, C-reactive protein and anti-Müllerian hormone in bitches affected by pyometra

The work was aimed to research into the vital signs, haematological and biochemical parameters, acute-phase protein concentrations (CRP, albumin), progesterone (PG) and anti-Müllerian hormone (AMH) concentrations in bitches with pyometra and their comparison with those in healthy bitches. In addition, the goal of this work was to assess if some of the tested parameters may be used as a biomarker in the diagnostics of pyometra and the monitoring of the postoperative recovery. Forty 3-6-year-old bitches of various breeds were included in the research and allotted to two groups: the control (C, n = 20) and the diseased - bitches diagnosed with pyometra (P, n = 20). Blood samples for the analyses were taken immediately before surgery (0 h), and 12 h, 24 h, 48 h and 72 h after, excepting for AMH and PG concentrations, which were determined only at 0 h. Clinical examination detected significantly higher respiration rates in bitches with pyometra in comparison to healthy ones at all time points, higher heart rates before and 12 h after surgery, and higher body temperature before and 12 h, 48 h and 72 h post operation (p < .01). Significantly higher concentrations of CRP (p < .01) and lower concentrations of albumin were detected in bitches with pyometra in comparison to their healthy counterparts at all time points. Progesterone and AMH concentration analysis immediately before surgery detected significantly higher levels of the hormone in bitches with pyometra than in the control (p < .01). The inflammatory reaction of the endometrium resulted in a significant AMH concentration increase, whilst increased CRP concentrations and lower albumin concentrations throughout the research may be used as biomarkers of proinflammatory activities, that is of the acute-phase response.

Changes in Proteins in Saliva and Serum in Equine Gastric Ulcer Syndrome Using a Proteomic Approach

Simple Summary

Equine gastric ulcer syndrome (EGUS) is a highly prevalent disease with a major clinical importance due to its negative effects on the welfare and performance of horses. EGUS can be distinguished into two different diseases depending on which anatomical region is affected: equine glandular gastric disease (EGGD), in which there is a lesion in the glandular stomach, and equine squamous gastric disease (ESGD), in which the alteration appears in the non-glandular stomach. EGUS has nonspecific clinical signs, and its underlying mechanism has not been completely elicited. Therefore, it would be of interest to clarify the pathophysiology and identify potential biomarkers of this syndrome. This study detected differences in the salivary and serum proteome between horses with EGUS and healthy horses, and also between horses with EGGD and ESGD. The most upregulated proteins in EGGD were related to the immune activation whereas, in horses with ESGD, the proteins with the most significant changes were associated with the squamous cell regulation and growth. Compared to serum, saliva had a higher number of proteins showing significant changes and also showed a different pattern of changes, indicating that the proteins in both fluids show a different response to the disease and can provide complementary information.

Abstract

Changes in the salivary proteome in 12 horses with the two diseases included in equine gastric ulcer syndrome (EGUS), equine glandular gastric disease (EGGD) (n = 6) and equine squamous gastric disease (ESGD) (n = 6), were evaluated using a high-resolution LC-MS/MS analysis of TMT-labelled peptides and compared to 10 healthy control horses. Serum was also analysed for comparative purposes. The comparison between the horses with EGGD and controls showed significant changes in 10 salivary proteins, whereas 36 salivary proteins were differently abundant between ESGD and control groups. The most upregulated proteins in the case of EGGD were related to immune activation whereas, in horses with ESGD, the most significantly changed proteins were associated with squamous cell regulation and growth. Compared to serum, saliva showed a higher number of proteins with significant changes and a different pattern of changes. The proteins identified in our study, in addition to providing new information about the pathophysiological mechanisms in these diseases, could have the potential to be novel biomarkers for the diagnosis or monitoring of EGGD and ESGD.

Assessment of salivary alpha-amylase and cortisol as a pain related stress biomarker in dogs pre-and post-operation

Background

The use of salivary biomarkers has garnered attention because the composition of saliva reflects the body’s physiological state. Saliva contains a wide range of components, including peptides, nucleic acids, electrolytes, enzymes, and hormones. It has been reported that salivary alpha-amylase and cortisol are biomarkers of stress related biomarker in diseased dogs; however, evaluation of salivary alpha-amylase and cortisol pre- and post- operation has not been studied yet. The aim of this study was to evaluate salivary alpha-amylase and cortisol levels in dogs before and after they underwent surgery and investigate the association between the salivary alpha-amylase and cortisol activity and pain intensity. For this purpose, a total of 35 dogs with disease-related pain undergoing orthopedic and soft tissue surgeries were recruited. Alpha-amylase and cortisol levels in the dogs’ saliva and serum were measured for each using a commercially available canine-specific enzyme-linked immunosorbent assay kit, and physical examinations (measurement of heart rate and blood pressure) were performed. In addition, the dogs’ pre- and post-operative pain scores determined using the short form of the Glasgow Composite Measure Pain Scale (CMPS-SF) were evaluated.

Results

After surgery, there was a significant decrease in the dogs’ pain scores (0.4-fold for the CMPS-SF, p < 0.001) and serum cortisol levels (0.73-fold, p < 0.01). Based on their pre-operative CMPS-SF scores, the dogs were included in either a high-pain-score group or a low-pain-score group. After the dogs in the high-pain-score group underwent surgical intervention, there was a significant decrease in their CMPS-SF scores and levels of salivary alpha-amylase, serum alpha-amylase, and serum cortisol. Additionally, there was a positive correlation between salivary alpha-amylase levels and CMPS-SF scores in both the high- and low-pain-score groups.

Conclusions

The measurement of salivary alpha amylase can be considered an important non-invasive tool for the evaluation of pain-related stress in dogs.

Changes in saliva proteins in cows with mastitis: A proteomic approach

This study aimed to evaluate the possible saliva proteome changes in cows with mastitis using a Tandem Mass Tags (TMT) proteomics approach. For this purpose, the salivary proteomes from healthy cows and cows with mastitis were analysed, and their serum proteomes were also studied for comparative purposes. A total of eight saliva and serum paired samples for each group were used for the proteomic study, and eight additional samples for each group were analysed in the analytical and overlap performance studies. In saliva samples, 2192 proteins were identified, being sixty-three differentially modulated in mastitis. In serum, 1299 proteins were identified, being twenty-nine differentially modulated in mastitis. Gamma glutamyl transferase (γGT) in saliva and serum amyloid A (SAA) were validated by commercially available automated assays. In conclusion, there are changes in protein expression and metabolic pathways in saliva and serum proteomes of cows with mastitis, showing different response patterns but complementary information.