Discovery proteomics to detect salivary biomarkers in dog and human periodontitis: Mass spectrometry-based analysis.

Periodontitis, prevalent in humans and dogs, is a chronic inflammatory disease affecting the oral hard and soft tissues. Salivary proteomics and protein homology may offer a non-invasive diagnosis, benefiting both species due to similarities in disease etiology and progression. This study compared (i) the proteomics profile of healthy and periodontitis dogs using mass spectrometry; and (ii) the protein homology of the identified differentially expressed proteins between humans and dogs. Twenty dogs were examined over six months, divided into two groups: ten healthy (control) and ten with periodontitis. Saliva samples were collected and analyzed using mass spectrometry. The study identified 855 proteins in healthy dogs and 849 in dogs with periodontitis, with a 96 % overlap. Notable shared proteins included abnormal spindle-like microcephaly-associated protein homolog, DNA-dependent protein kinase catalytic subunit, and myosin-2, while specific proteins, including myosin-13 and fibrocystin, were unique to healthy dogs, and G2/mitotic-specific cyclin-B3 and hemoglobin subunit beta were unique to periodontitis dogs. In periodontitis dogs, proteins adenosine receptor A2b, apoptotic protease-activating factor 1, and calcitonin gene-related peptide 1 were upregulated, and cytotoxic T-lymphocyte protein 4, laforin, and lens fiber major intrinsic protein were downregulated. The proteins were involved in second messenger signaling and drug response pathways, with complex interaction networks identified. Homology between human and dog proteins ranged from 78.3 % to 100 %, suggesting that these shared proteins could be relevant for cross-species periodontal research and diagnostics.