Brucella canis is pathogenic for dogs and humans. Serological diagnosis is a cost-effective approach for disease surveillance, but a major drawback of current serological tests is the cross-reactivity with other bacteria that results in false positive reactions, and development of indirect tests with improved sensitivity and specificity remain a priority. A western blotting assay was developed to define the serum antibody patterns associated to infection using a panel of positive and negative dog sera. B. canis positive sera recognized immunogenic bands ranging from 7 to 30 kDa that were then submitted to ESI–LC-MS/MS and analyzed by bioinformatics tools. A total of 398 B. canis proteins were identified.. Bioinformatics tools identified 16 non cytoplasmic immunogenic proteins predicted as non-homologous with the most important Brucella cross-reactive bacteria and 9 B. canis proteins non-homologous to B. ovis; among the latter, one resulted non-homologous to B. melitensis. The western blotting test developed was able to distinguish between infected and non-infected animals and may serve as confirmatory test for the serological diagnosis of B. canis. The mass spectrometry and in silico results lead to the identification of specific candidate antigens that pave the way for the development of more accurate indirect diagnostic tests.

Inflammatory bowel disease (IBD), which includes ulcerative colitis (UC) and Crohn’s disease (CD), is characterized by chronic gastrointestinal inflammation. A high unmet need exists for non-invasive biomarkers in IBD to detect mucosal inflammation to monitor changes in disease severity and guide treatment decisions. Fecal proteomics has the potential to allow frequent, non-invasive monitoring of biomarkers in stool of IBD patients, however the fecal proteome remains under explored. Here a data-independent acquisition LC-MS/MS approach was used to profile the human fecal proteome in two independent cohorts of IBD patients and healthy controls (HC) to identify non-invasive biomarkers reflective of disease activity. 688 human proteins were quantified, with 523 measured in both cohorts. In UC stool 96 proteins were differentially abundant and in CD stool 126 proteins were differentially abundant compared to HC stool (absolute log2 fold change >1, p-value <0.05). Many of these fecal proteins are associated with infiltrating immune cells and ulceration/rectal bleeding, which are hallmarks of IBD pathobiology. Mapping of the identified fecal proteins to a whole blood single-cell RNA sequencing data set revealed the involvement of various immune cell subsets to the IBD fecal proteome. Findings from this study not only confirmed the presence of established fecal biomarkers for IBD, such as calprotectin and lactoferrin, but also revealed new fecal proteins from multiple pathways known to be dysregulated in IBD. These novel proteins could serve as potential non-invasive biomarkers to monitor specific aspects of IBD disease activity which could expedite clinical development of novel therapeutic targets.

Purpose: Brain tumors, whether primary or secondary, have limited information about proteomic changes despite advances in the understanding of the driver gene mutations and heterogeneity within tumor cells. The purpose of this study is to distinguish primary and secondary brain tumors based on proteomics. Experimental Design: We assembled the most common primary tumors as follows: gliomas from WHO grade II to IV with or without IDH1 mutations; and BrMs with a wide range, including lung cancer (L.C), breast cancer (B.C), ovarian cancer (O.C), and colorectal cancer (C.C). A total of 29 tissue samples were analyzed by label free quantitative mass spectrometry-based proteomics. Results: In total, 8,370 protein groups were identified, and approximately 4,000 quantified protein groups were adopted for further analysis. Proteomic analysis of metastatic tumors reveals conserved features across multiple cancers. While proteomic heterogeneities were found for discriminating low- and high-grade of gliomas, as well as IDH1 mutant and wild-type gliomas. And distinct pathway-level differences among these two types of brain malignancies were revealed. The characteristic pathways of BrMs focused on proliferation and immunomodulation after colonizing the brain, whereas invasion processes were notably activated in gliomas. Conclusions and Clinical Relevance: We elucidated an extensive proteomic landscape of BrMs and gliomas, providing information for the development of potential therapeutic and diagnostic strategies for type-specific brain tumors.