Proteomic Techniques Research Articles

Glutamate molecular structure and protein affect the inhibition of breast cancer cell metastasis: Cell-derived exosomes inhibitory effects through the MAPK signaling pathway.

The aim of this study was to investigate the inhibitory effect of glutamate molecular structure and protein on breast cancer cell metastasis and the potential inhibitory mechanism of cell-derived exosomes via MAPK signaling pathway. Breast cancer cell lines with high metastatic potential were selected by in vitro cell culture technique. The effects of specific inhibitors of glutamic acid on the proliferation and metastasis of breast cancer cells were studied. Changes in protein expression profiles were analyzed by proteomics techniques to identify key proteins associated with breast cancer metastasis. Breast cancer cells were treated with inhibitors of the MAPK signaling pathway to evaluate their effect on cell metastasis and compare with exosome treatment. The results showed that the specific inhibitors of glutamate molecular structure could significantly inhibit the proliferation and metastasis of breast cancer cells. Proteomic analysis revealed several down-regulated proteins that are closely related to breast cancer metastasis.

Mitochondrial oxidative stress related LncRNA predict cervical cancer prognosis and immunotherapy response: Molecular structure and protein interaction of ribosomal protein L34.

The purpose of this study was to investigate the predictive value of mitochondrial oxidative stress-related LncRNA in cancer prognosis and immunotherapy response, and to further analyze the molecular structure of ribosomal protein L34 and its interaction mechanism with the protein. We screened lncrnas associated with mitochondrial oxidative stress, evaluated their expression patterns in different cancer types, and analyzed the three-dimensional structure of ribosomal protein L34 and its interaction network with other proteins. In this study, public databases were used to screen out lncrnas associated with mitochondrial oxidative stress. Bioinformatic analysis, including gene expression profile analysis, survival analysis and functional enrichment analysis, was used to evaluate the expression patterns of these lncrnas in different cancer types and their relationship with prognosis. The interacting proteins of ribosomal protein L34 were identified by proteomic techniques. The three-dimensional structure of ribosomal protein L34 and its binding mode with interacting proteins were studied by molecular docking and dynamic simulation methods. The results showed that the screened lncrnas showed significant expression differences in multiple cancer types and were closely related to the survival rate of patients. The three-dimensional structure of ribosomal protein L34 reveals key amino acid residues and binding sites for its interactions with specific proteins. Functional enrichment analysis showed that these lncrnas may affect the development of cancer through regulating oxidative stress response, cell cycle and apoptosis. The interaction network of ribosomal protein L34 reveals its central role in protein synthesis and cellular stress response.

Multidrug-resistant Gram-negative bacterial infections.

Multidrug-resistant Gram-negative bacterial infections cause significant morbidity and mortality globally. These pathogens easily acquire antimicrobial resistance (AMR), further highlighting their clinical significance. Third-generation cephalosporin-resistant and carbapenem-resistant Enterobacterales (eg, Escherichia coli and Klebsiella spp), multidrug-resistant Pseudomonas aeruginosa, and carbapenem-resistant Acinetobacter baumannii are the most problematic and have been identified as priority pathogens. In response, several new diagnostic technologies aimed at rapidly detecting AMR have been developed, including biochemical, molecular, genomic, and proteomic techniques. The last decade has also seen the licensing of multiple antibiotics that have changed the treatment landscape for these challenging infections.

Descriptive analysis of protein expression variations during pupal development of Chrysomya megacephala (Diptera: Calliphoridae) using label-free proteomic techniques

Abstract Age estimation is a critical aspect of forensic entomology, especially in the examination of pupae. The use of proteins as a means for age identification shows great promise. In this study, proteomic techniques were employed to investigate differentially expressed proteins (DEPs) during the intrapuparial stage of Chrysomya megacephala. Specimens were sampled at four distinct time points: 0 h (Group A), 24 h (Group B), 48 h (Group C), and 72 h (Group D). Our analysis uncovered 56 DEPs between Groups B and A, 116 DEPs between Groups C and A, and a total of 152 DEPs between Groups D and A. These DEPs were categorized into nine clusters based on their expression patterns. Cluster 1 exhibited an increasing trend in protein expression, while Cluster 4 displayed the opposite pattern. Clusters 2, 6, and 9 showed an initial rise followed by a decline, whereas Cluster 3 demonstrated the reverse trend. Cluster 8 indicated an initial rise, a subsequent drop, and another rise, while Cluster 7 showed an initial decrease, followed by an increase and a minor decrease. Notably, the C-type lectin domain-containing (CTLD) protein and Failed axon connections (Fax) protein consistently displayed an upward trend. These two DEPs were selected for validation using the parallel reaction monitoring technique (PRM)-targeted proteomics, confirming the trends observed in the initial analysis. In summary, this study highlights the potential of using proteins as reliable biomarkers for estimating pupal age.

Unlocking Platelet Mechanisms through Multi-Omics Integration: A Brief Review.

Platelets, tiny cell fragments measuring 2-4 μm in diameter without a nucleus, play a crucial role in blood clotting and maintaining vascular integrity. Abnormalities in platelets, whether genetic or acquired, are linked to bleeding disorders, increased risk of blood clots, and cardiovascular diseases. Advanced proteomic techniques offer profound insights into the roles of platelets in hemostasis and their involvement in processes such as inflammation, metastasis, and thrombosis. This knowledge is vital for drug development and identifying diagnostic markers for platelet activation. Platelet activation is an exceptionally rapid process characterized by various posttranslational modifications, including protein breakdown and phosphorylation. By utilizing multiomics technologies and biochemical methods, researchers can thoroughly investigate and define these posttranslational pathways. The absence of a nucleus in platelets significantly simplifies mass spectrometry-based proteomics and metabolomics, as there are fewer proteins to analyze, streamlining the identification process. Additionally, integrating multiomics approaches enables a comprehensive examination of the platelet proteome, lipidome, and metabolome, providing a holistic understanding of platelet biology. This multifaceted analysis is critical for elucidating the complex mechanisms underpinning platelet function and dysfunction. Ultimately, these insights are crucial for advancing therapeutic strategies and improving diagnostic tools for platelet-related disorders and cardiovascular diseases. The integration of multi-omics technologies is paving the way for a deeper understanding of platelet mechanisms, with significant implications for biomedical research and clinical applications.

Lipid Nanoparticles in Medicine: Advances in Diagnostics, Therapeutics, and Future Directions

Abstract Lipid nanoparticles (LNPs) have become a critical tool in modern medicine, particularly in diagnostics and therapy. Various synthesis techniques, including ultrasonication, high-pressure homogenization, solvent evaporation, and microemulsion, have been employed to produce nanoparticles with desired properties. Modification techniques such as surface functionalization, polymer coating, PEGylation, and ligand conjugation further enhance their efficacy and biocompatibility. This study highlights the recent advances in the application of LNPs for improving diagnostic accuracy and therapeutic outcomes. In diagnostics, LNPs enhance visualization, bioimaging, and analytical methods, especially through genomic, proteomic, and immunoassay-based techniques, as well as plasmonic biosensors. In therapy, LNPs are utilized in innovative treatments such as plasmonic photothermal and photodynamic therapies, antibacterial applications, and drug delivery systems. These nanoparticles serve as effective carriers for drugs, genes, and antibodies, improving targeted delivery and therapeutic efficacy. Despite their promising potential, challenges related to safety, scalability, and long-term impacts remain, and this research outlines future perspectives on overcoming these barriers to further integrate LNPs into clinical applications.

Proteomics Response of Photosynthetic Machinery to Abiotic Stresses: A Review

Abiotic stress, including drought, salinity, extreme temperatures, and light intensity, profoundly affects plant growth and development. Plants being sessile cannot escape the stress conditions, , thus have developed either evading or tolerance mechanisms during evolution. In plants several processes are affected by drought e.g. there is inhibition of growth, reduction in photosynthesis, and yield, and increased membrane damage. Plants respond to drought or tolerate stress by downregulation of growth, photosynthetic machinery and membrane fluidity, increased cuticle thickness, osmolyte accumulation, increased defense chemicals, and secondary metabolites, and stress responding proteins e.g. Late Embryogenic Abundance and Heat Shock proteins etc. The root architecture is elaborated, and leaf rolling occurs. Futher, there is an increase in the cell's antioxidant potential and antioxidant enzyme activity. Most of these mechanisms are investigated using proteomics and protein techniques. With the advent of sensitive proteomics techniques and the availability of databases for several plants, proteomics experiments have become routine in stress based studies. Current review highlights the modulation in the photosynthetic and chloroplastic proteins in higher plants that proteomics and other protein determination studies have revealed, in response to stress treatment. It specifically discusses the latest developments in terms of protein changes in leaves or other tissues from the studies using stress treatment, since several reviews have already covered the earlier findings. Moreover, it further discusses the future role of proteomics studies in elucidating stress mechanisms in plants.

Proteomics: An In-Depth Review on Recent Technical Advances and Their Applications in Biomedicine.

Proteins hold pivotal importance since many diseases manifest changes in protein activity. Proteomics techniques provide a comprehensive exploration of protein structure, abundance, and function in biological samples, enabling the holistic characterization of overall changes in organisms. Nowadays, the breadth of emerging methodologies in proteomics is unprecedentedly vast, with constant optimization of technologies in sample processing, data collection, data analysis, and its scope of application is steadily transitioning from the bench to the clinic. Here, we offer an insightful review of the technical developments in proteomics and its applications in biomedicine over the past 5 years. We focus on its profound contributions in profiling disease spectra, discovering new biomarkers, identifying promising drug targets, deciphering alterations in protein conformation, and unearthing protein-protein interactions. Moreover, we summarize the cutting-edge technologies and potential breakthroughs in the proteomics pipeline and provide the principal challenges in proteomics. Based on these, we aspire to broaden the applicability of proteomics and inspire researchers to enhance our understanding of complex biological systems by utilizing such techniques.

Intricacies during pregnancy with gestational diabetes mellitus

The study by Cao et al aimed to identify early second-trimester biomarkers that could predict gestational diabetes mellitus (GDM) development using advanced proteomic techniques, such as Isobaric tags for relative and absolute quantitation isobaric tags for relative and absolute quantitation and liquid chromatography-mass spectrometry liquid chromatography-mass spectrometry. Their analysis revealed 47 differentially expressed proteins in the GDM group, with retinol-binding protein 4 and angiopoietin-like 8 showing significantly elevated serum levels compared to controls. Although these findings are promising, the study is limited by its small sample size (n = 4 per group) and lacks essential details on the reproducibility and reliability of the protein quantification methods used. Furthermore, the absence of experimental validation weakens the interpretation of the protein-protein interaction network identified through bioinformatics analysis. The study's focus on second-trimester biomarkers raises concerns about whether this is a sufficiently early period to implement preventive interventions for GDM. Predicting GDM risk during the first trimester or pre-conceptional period may offer more clinical relevance. Despite its limitations, the study presents valuable insights into potential GDM biomarkers, but larger, well-validated studies are needed to establish their predictive utility and generalizability.

Evaluation of Eukaryotic mRNA Coding Potential.

It is widely discussed that eukaryotic mRNAs can encode several functional polypeptides. Recent progress in NGS and proteomics techniques has resulted in a huge volume of information on potential alternative translation initiation sites and open reading frames (altORFs). However, these data are still incomprehensive, and the vast majority of eukaryotic mRNAs annotated in conventional databases (e.g., GenBank) contain a single ORF (CDS) encoding a protein larger than some arbitrary threshold (commonly 100 amino acid residues). Indeed, some gene functions may relate to the polypeptides encoded by unannotated altORFs, and insufficient information in nucleotide sequence databanks may limit the interpretation of genomics and transcriptomics data. However, despite the need for special experiments to predict altORFs accurately, there are some simple methods for their preliminary mapping.

Protein molecular structures of USP53, NPY2R, and DCTN1-AS1 and impact on tumors: Analysis of prognostic biomarkers for diffuse large B-cell lymphoma.

In the past few years, three protein molecules-USP53, NPY2R, and DCTN1-AS1-have garnered significant attention in scientific research due to their potential implications in tumor development. Mass spectrometry and proteomics techniques were used to analyze the three-dimensional structure of these protein molecules and predict their active sites and functional domains. The effects of USP53, NPY2R and DCTN1-AS1 on biological behavior of tumor cells were studied by constructing gene knockout and overexpression cell models. The data showed that when USP53 was overexpressed, there was a notable enhancement in both the proliferation and invasion capabilities of tumor cells, indicating its potential role in promoting cancer aggressiveness. Conversely, the knockout of USP53 resulted in a significant reduction of these capabilities, highlighting its importance in tumor cell behavior. Similarly, the overexpression of NPY2R correlated with an increased apoptosis rate among tumor cells, suggesting that this protein may play a role in regulating cell survival. On the other hand, the knockout of DCTN1-AS1 markedly diminished the metastatic ability of the tumor cells, emphasizing its potential involvement in cancer spread. Furthermore, the analysis of clinical data provided compelling evidence that high levels of USP53 and NPY2R expression are closely linked to a poor prognosis for patients, suggesting that these proteins could serve as negative prognostic indicators. In contrast, low levels of DCTN1-AS1 expression were found to predict a poor response to treatment, further underscoring its importance in the context of therapy outcomes.

Impact of arsenic exposure on the hepatic metabolic molecular network in obese pregnant mice using metabolomics and proteomics

Arsenic is a ubiquitous environmental toxin that can affect normal physiological processes. Although the health impacts of arsenic have been investigated, its influence on hepatic metabolism in obese pregnant women and the underlying mechanisms remain unclear. Multi-omics analysis, including metabolomics and proteomics, can improve the understanding of arsenic-induced hepatotoxicity in obese pregnant women. This study aimed to investigate the adverse effects of gestational arsenic exposure on hepatic metabolism in high-fat-diet-induced obese pregnant mice. Following arsenic exposure during pregnancy, the liver tissue was evaluated comprehensively using metabolomics and proteomics techniques combined with pathological and biochemical analyses. Arsenic exposure not only significantly increased lipid accumulation in the livers of obese pregnant mice but also elevated inflammatory factors and oxidative stress markers. Specifically, histopathological examination revealed more steatosis, inflammatory cell infiltration, and hepatocyte ballooning in the livers of arsenic-exposed mice than in those of controls. These changes indicate that arsenic exposure exacerbates hepatic lipid accumulation and induces liver damage in the context of obesity. Metabolomic analysis provided further insight into the metabolic-level disruption caused by arsenic exposure. Significant changes were observed in lipid metabolism pathways, particularly the arachidonic acid metabolism pathway. As arachidonic acid and its metabolites play important roles in inflammation and oxidative stress, this pathway may be critical in arsenic-induced hepatotoxicity. Additionally, proteomic analysis showed differences in the expression levels of several key proteins involved in lipid synthesis, oxidative stress, and inflammatory response. Notably, oxidative-stress-related proteins, including glutathione peroxidase 4 (GPX4), were upregulated, suggesting an increased oxidative burden. In summary, there are complex interaction mechanisms among arsenic exposure, inflammatory response, and related lipid metabolism. The integration of metabolomics and proteomics aided in clarifying the molecular alterations induced by arsenic. The results show that arsenic exposure significantly affects hepatic lipid metabolism in obese pregnant mice through multiple metabolic pathways and protein regulatory mechanisms. In addition to providing new insights into the relationship between arsenic exposure and obesity as well as related metabolic diseases, this study can act as a reference for environmental health risk assessment and the formulation of public health policies. This enhanced understanding of the adverse effects of arsenic on hepatic metabolism will contribute to the development of strategies for mitigating the health risks associated with environmental toxins, particularly for vulnerable groups such as obese pregnant women.

Comparison of Bacterial Intracellular and Secreted Proteins produced in Milk Versus Medium for Escherichia coli by Proteomic Analysis.

The growth and reproduction of microorganisms are dependent on nutrient supply. Here, Milk and LB media were utilized as nutrition sources for Escherichia coli, and the changes in bacterial and secretory proteins at 3 time points (3, 9, and 18 h) in the growth cycle were studied using a label-free proteomics technique. The findings revealed that the abundances of bacterial intracellular proteins inosine/xanthosine triphosphatase and universal stress protein F increase dramatically during the growth phase in milk and LB media. In terms of secretory proteins, RNase PH and tyrosine-tRNA ligase abundance increased dramatically, while outer membrane protein X and outer membrane protein C abundance decreased significantly from 3 to 18 h in both milk and LB conditions. Several bacterial intracellular and secretory proteins showed media-dependent changes, including hydrogenase-2 and s-adenosylmethionine synthase, which were only found in the LB medium. In contrast, DNA polymerase III subunit α and cold shock-like protein CspD (CspD) have been discovered only in milk. The 2 media shared the differential abundance of proteins involved in small molecule binding and small molecule metabolic process pathways. The differentially expressed intracellular proteins of E. coli cultured in milk were associated with membrane trafficking and signal transduction pathways. The findings improve our understanding of changes in E. coli bacterial intracellular proteins and secretory proteins in response to nutritional stimuli, as well as provide a new perspective and foundation for investigating its adaptive mechanisms in a variety of environments, potentially leading to better prevention and control strategies.

Cancer vaccines: an update on recent achievements and prospects for cancer therapy.

Decades of basic and translational research have led to a momentum shift in dissecting the relationship between immune cells and cancer. This culminated in the emergence of breakthrough immunotherapies that paved the way for oncologists to manage certain hard-to-treat cancers. The application of high-throughput techniques of genomics, transcriptomics, and proteomics was conclusive in making and expediting the manufacturing process of cancer vaccines. Using the latest research technologies has also enabled scientists to interpret complex and multiomics data of the tumour mutanome, thus identifying new tumour-specific antigens to design new generations of cancer vaccines with high specificity and long-term efficacy. Furthermore, combinatorial regimens of cancer vaccines with immune checkpoint inhibitors have offered new therapeutic approaches and demonstrated impressive efficacy in cancer patients over the last few years. In the present review, we summarize the current state of cancer vaccines, including their potential therapeutic effects and the limitations that hinder their effectiveness. We highlight the current efforts to mitigate these limitations and highlight ongoing clinical trials. Finally, a special focus will be given to the latest milestones expected to transform the landscape of cancer therapy and nurture hope among cancer patients.

RORc expressing immune cells negatively regulate tertiary lymphoid structure formation and support their pro-tumorigenic functions.

RORc-expressing immune cells play important roles in inflammation, autoimmune disease and cancer. They are required for lymphoid organogenesis and have been implicated in tertiary lymphoid structure (TLS) formation. TLSs are formed in many cancer types and have been correlated with better prognosis and response to immunotherapy. In liver cancer, some TLSs are pro-tumorigenic as they harbor tumor progenitor cells and support their growth. The processes involved in TLS development and acquisition of pro- or anti-tumorigenic roles are largely unknown. This study aims to explore the role of RORc-expressing cells in TLS development in the context of inflammation-associated liver cancer. IKKβ(EE)Hep mice, exhibiting chronic liver inflammation, TLS formation and liver cancer, were crossed with RORc knockout mice to explore RORc's effect on TLS and tumor formation. TLS phenotypes were analyzed using transcriptional, proteomic, and immunohistochemical techniques. CD4, CD8, and B cell depletions were used to assess their contribution to liver TLS and tumor formation. RORc-expressing cells are detected within TLSs of both human patients and mice developing intrahepatic cholangiocarcinoma. In mice, these cells negatively regulate TLS formation, as excess TLSs form in their absence. CD4 cells are essential for liver TLS formation, while B cells are required for TLS formation specifically in the absence of RORc-expressing cells. Importantly, in chronically inflamed livers lacking RORc-expressing cells, TLSs become anti-tumorigenic, reducing tumor load. Anti-tumorigenic TLSs revealed enrichment of exhausted CD8 cells with effector functions, germinal center B cells and plasma cells. B cells are key in limiting tumor development, possibly via tumor-directed antibodies. RORc-expressing cells negatively regulate B cell responses and facilitate the pro-tumorigenic functions of hepatic TLSs.

Cyclin-dependent kinases (CDKs) are key genes regulating early development of Neptunea arthritica cumingii: evidence from comparative transcriptome and proteome analyses

In this study, we applied comparative transcriptomics and proteomics techniques to systematically investigate the dynamic expression patterns of genes and proteins at various stages of early embryonic development of the gastropod Neptunea arthritica cumingii. Twelve cyclin-dependent kinase (CDKs) genes and five downstream proteins associated with these CDKs were identified. Through techniques such as qRT-PCR, our data elucidate for the first time the regulatory functions of CDK family genes and establish CDKs as a pivotal gene cluster in the early embryonic development of N. cumingii. These findings not only enhance the understanding of molecular developmental biology in N. cumingii and marine gastropods in general but also provide significant insights into the mechanisms involved in early embryonic development in N. cumingii. Furthermore, our results provide theoretical guidance for advancing artificial breeding technology for N. cumingii.

Integral Solvent-Induced Protein Precipitation for Target-Engagement Studies in Plasmodium falciparum.

The limited understanding of the mechanism of action (MoA) of several antimalarials and the rise of drug resistance toward existing malaria therapies emphasizes the need for new strategies to uncover the molecular target of compounds in Plasmodium falciparum. Integral solvent-induced protein precipitation (iSPP) is a quantitative mass spectrometry-based (LC-MS/MS) proteomics technique. The iSPP leverages the change in solvent-induced denaturation of the drug-bound protein relative to its unbound state, allowing identification of the direct drug-protein target without the need to modify the drug. Here, we demonstrate proof-of-concept of iSPP in P. falciparum (Pf) lysate. At first, we profiled the solvent-induced denaturation behavior of the Pf proteome, generating denaturation curves and determining the melting concentration (CM) of 2712 proteins. We then assessed the extent of stabilization of three antimalarial target proteins in multiple organic solvent gradients, allowing for a rational selection of an optimal solvent gradient. Subsequently, we validated iSPP by successfully showing target-engagement of several standard antimalarials. The iSPP assay allows the testing of multiple conditions within reasonable LC-MS/MS measurement time. Furthermore, it requires a minimal amount of protein input, reducing culturing time and simplifying protein extraction. We envision that iSPP will be useful as a complementary tool for MoA studies for next-generation antimalarials.

Identification of TIGAR, a direct proteomic target associated with the hypoglycemic effect of Berberine

Diabetes mellitus is a global chronic metabolic disease and the prevalence of diabetes mellitus is increasing dramatically every year. Berberine (BBR) from Coptidis Rhizoma has potent hypoglycemic effects, however, the specific proteins targeted by berberine that contribute to its hypoglycemic action remain to be elucidated. In this work, TIGAR (TP53-induced glycolysis and apoptosis regulator) was identified as a direct target protein for berberine using activity-based protein profiling (ABPP) and other chemical proteomics techniques with active photoaffinity probes as chemical tools. In addition, the study revealed that berberine-targeted TIGAR attenuated the conversion of fructose-2, 6-bisphosphate to fructose-6-phosphate. This study demonstrated an innovative mechanism by which berberine directly targets TIGAR and its hypoglycemic effects. Therefore, TIGAR emerges as a novel target for the treatment of diabetes mellitus, with TIGAR inhibitors offering a new and promising therapeutic strategy for managing the disease.

The Microenvironment in an Experimental Model of Acute Pancreatitis Can Modify the Formation of the Protein Corona of sEVs, with Implications on Their Biological Function.

A considerable number of the physiological functions of extracellular vesicles are conditioned by the protein corona attached to their surface. The composition of this corona is initially defined during their intracellular synthesis, but it can be subsequently modified by interactions with the microenvironment. Here, we evaluated how the corona of small extracellular vesicles exposed to the inflammatory environment generated in acute pancreatitis is modified and what functional changes occur as a result of these modifications. Small extracellular vesicles obtained from a pancreatic cell line were incubated with the ascitic fluid generated in experimental acute pancreatitis in rats. Using proteomic techniques, we detected the appearance of new proteins and an increase the uptake of extracellular vesicles by certain cell types and the response induced in inflammatory cells. The inhibition of different pattern recognition receptors reversed this activation, indicating that some of these effects could be due to binding of damage-associated molecular patterns to the corona. All of this indicates that in pathologies such as acute pancreatitis, characterized by an inflammatory response and intense tissue damage, the microenvironment substantially influences the corona of extracellular vesicles, thus altering their behavior and enhancing their inflammatory activity.

Salivary Proteomics for Detecting Novel Biomarkers of Periodontitis: A Systematic Review.

Salivary content is regarded as a powerful diagnostic window for oral and systemic diseases and the proteomic profile could be useful to distinguish between different periodontal conditions. The aim of the present systematic review was to assess distinctive salivary proteins identified through untargeted proteomics in periodontitis patients compared to periodontally healthy and gingivitis subjects, as well as to provide a qualitative methodological assessment of the current literature. Relevant studies identified from Medline via PubMed, Scopus, Embase, and Cochrane Library databases were retrieved to answer the following PECO question: "In systemically healthy individuals, are there any differences in salivary protein expression profiles assessed in proteomics studies between patients with periodontitis and periodontally healthy or gingivitis subjects?" Moreover, diagnostic utility of the identified markers was sought via a targeted literature search and further quantitative assessment. A modified version of the QUADAOMICS tool was used for the quality assessment of the included studies. After screening 461 relevant articles, a total of 13 studies were selected. The number of identified discriminant salivary proteins ranged from 2 to 4161. However, it was possible to identify proteins that were consistently over- or under-expressed in periodontitis patients in at least 3 studies. Among these, complement C3, profilin-1, SA100A8, and fibrinogen were consistently reported as increased in periodontitis, while cystatin-SN and leukocyte elastase inhibitor were more elevated in periodontally healthy controls. Only 4 studies reported diagnostic accuracy measures, with SA100A8 showing an area under the curve of 0.71 (95% CI: 0.66-0.75) in meta-analysis. Untargeted proteomics techniques identified some key biological molecules which were consistently reported to be over- or under-expressed in periodontitis. These findings could be useful to support novel candidate biomarkers for periodontitis. The high level of heterogeneity in methods and reporting urge to develop standardized protocols to be implemented in this research field (PROSPERO CRD42022299826).