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.

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.

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: Merozoites are the only extracellular form of blood stage parasites, making it a worthwhile target for vaccine and drug development. Multiple invasins that are stored in the merozoite apical organelles, are secreted just prior to invasion, and mediates its interaction with host cell. A comprehensive identification of all these secreted invasins is lacking and this study addresses that gap. Experimental design: Pf3D7 merozoites were enriched and were triggered to discharge apical organelle contents by exposure to ionic conditions mimicking that of blood plasma. The secreted proteins were separated from cellular contents and both the fractions were subjected to proteomic analysis. Also, the identified secreted proteins were subjected to gene ontology and PPI network analysis. Results: A total of 63 proteins were identified in the secretory fraction with membrane and apical organellar localization. This includes various MSPs, micronemal EBAs, various rhoptry bulb proteins, which plays a crucial role in initial and late attachment of the merozoite with the RBC, and harboured multiple linear B cell epitopes. Conclusion and clinical relevance: We, for the first time, report the secretory repertoire of merozoite. This information can be utilized to develop better invasion blocking multisubunit vaccines, comprising of immunological epitopes from several secreted invasins.

This study sought to analyze the impact of Metabolic Syndrome (MeS) and Type 2 Diabetes (T2DM) on metabolism and their relationship of Body Mass Index (BMI) and to identify potential predictive protein biomarkers for MeS and T2DM. The proteomes of saliva and blood, clinical parameters were analyzed in 103 adult individuals from the State of Rio de Janeiro, Brazil, a mixed-race population. Healthy individuals were sorted by their Body Mass Index (BMI) in normal (n=29), overweight (n=25) and obese (n=15) and were compared with individuals with MeS (n=23) and T2DM (n=11). Random forest predictive model revealed that 3 clinical variables, BMI, HOMA-IR, and fasting blood glucose, are most important for predicting MeS and T2DM. A total of 6 plasmatic proteins (ABCD4, LDB1, PDZ, Podoplanin, Lipirin-alpha-3 and WRS) and 6 salivary proteins (Hemoglobin subunit beta, POTE ankyrin domain family member E, T cell receptor alpha variable 9-2, Lactotransferrin, Cystatin-S, Carbonic anhydrase 6), are enhanced in T2DM and in MeS. Salivary and plasmatic proteomes, in a population of brazil, demonstrates that the physiopathological conditions associated with abnormal weight gain, T2DM, and MeS share similar modifications in protein composition, offering potential predictive biomarkers, potentially mitigating the adverse health consequences of these metabolic disorders.

Background: Biomarkers for metabolic dysfunction-associated steatohepatitis (MASH) have been considered based on proteomic and lipidomic data from plasma and liver tissue without clinical benefits. This study evaluated proteomics-based plasma and liver tissue biomarkers collected simultaneously from patients with metabolic dysfunction-associated steatotic liver disease (MASLD). Methods: Liver tissue samples and plasma samples were collected during liver biopsy for diagnosis. Untargeted proteomics was performed on 64 patients with MASLD. Results: Twenty plasma proteins were up or downregulated in patients with MASH compared with those without MASH. The biomarkers utilizing the best combinations of these plasma proteins had an area under the receiver operating curve (AUROC) of 0.671 for detecting those with MASH compared with those without it. However, none of the 20 plasma proteins were represented among the significantly regulated liver tissue proteins in patients with MASH. Ten of them displayed a trend and relevance in liver tissue with MASLD progression. These ten plasma proteins had an AUROC of 0.793 for MASH identification and higher positive and negative predictive values. Conclusion: The plasma and liver protein expressions of patients with MASH were not directly comparable. Plasma protein biomarkers that are also expressed in liver tissue can help improve MASH detection.

Saliva has emerged as a promising diagnostic resource due to its accessibility, non-invasiveness, and repeatability, enabling early disease detection and timely intervention. However, current studies often overlook the distinction between whole saliva (WS) and cell-free saliva (CFS). This study aims to compare the proteomic profiles of WS and CFS, both with and without low-abundance proteins enrichment using nanoparticles, employing DIA-MS technology. Our findings reveal a substantial enhancement in the detectability of low-abundance proteins in saliva with utilization of nanoparticles, enabling identification of 12%-15% low-abundance proteins previously undetectable in WS or CFS. In total, 3817 saliva proteins were identified, with 3413 found in WS and 2340 in CFS. More interestingly, we found that it wasn’t the similarity of the samples that did the clustering, but rather it depended more on the different detection methods and sample types. And the predominant functions of the identified proteins in WS were related to oxidative phosphorylation and neurodegenerations, whereas those in CFS were primarily associated with nitrogen and glycosaminoglycan metabolism. And both exhibited functions in immune response and proteasome. This study represents the first comparison of WS and CFS, providing valuable experimental evidence for guiding the selection of research subjects in future salivomics studies.