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

Abstract

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.

Changes in the Saliva Proteome of Pigs with Diarrhoea Caused by Escherichia coli

“…In addition, it has been described to capture bacterial siderophores produced by pathogenic bacteria, such as E. coli and, indeed, Lcn2-deficient mice are prone to infection and sepsis [ 16 ]. Although in our study LCN increased, in a previous report it was observed a decrease of LCN in the saliva of pigs with Streptococcus suis infection [ 4 ]. Further studies should be undertaken to elucidate the mechanisms involved in the change in LCN since in some cases, such as in the Streptococcus suis infection, the decrease of lipocalin could indicate a high susceptibility to worsening sepsis [ 4 ].…”

“…Overall, in our report, we found changes in proteins in saliva related to inflammation and the immune system, as have been described in saliva in pigs with sepsis experimentally induced by LPS administration and other infectious diseases such as S. suis infection [ 3 , 4 ].…”

“…ADA was selected to validate the proteomic results due to the existence of an automated assay validated for pigs [ 22 ]. ADA increases inflammation and sepsis in the saliva of pigs [ 4 , 11 ]. The increase in ADA found in our proteomic study was also confirmed in the larger population of pigs with diarrhoea with E. coli compared to healthy pigs, corroborating the higher levels of this protein in saliva in this disease, possibly reflecting activation of inflammation and the immune system.…”

“…Aldolase A and serpin 12 were proteins in saliva that were significantly upregulated in sepsis. In addition, the proteome of saliva in pigs with Streptococcus suis infection has been studied, with the proteins metavinculin (VCL) and desmocollin-2 (DSC2) showing the highest relative abundance [ 4 ]. Moreover, proteomic changes have been reported in the saliva of pigs in situations of compromised welfare, with the proteins cornulin, heat shock protein 27, and lactate dehydrogenase (LDH) showing significant increases, and the immunoglobulin J chain showed a significant decrease [ 5 ].…”

Emerging Approaches for Mitigating Biofilm-Formation-Associated Infections in Farm, Wild, and Companion Animals

“…Streptococcus suis is the most important bacterial agent that causes meningitis in pigs. Disease caused by S. suis is more prevalent in nursery pigs, but sucklers and young fatteners can also be affected [ 109 , 110 ]. The ability of several pathogenic microorganisms to form biofilms on host surfaces contributes to their virulence, and recent studies have found that S. suis can protect itself by forming biofilms, since the ability of bacteria to attach and colonize host tissues is a critical step in the initiation of infection, leading to increased drug resistance and prolonged disease [ 80 , 111 ].…”