Zebrafish as a new model to study effects of periodontal pathogens on cardiovascular diseases

Effects and mechanisms of Porphyromonas gingivalis outer membrane vesicles induced cardiovascular injury

BACKGROUND

The outer membrane vesicles (OMVs) derived from Porphyromonas gingivalis (P. gingivalis) have long been acknowledged for their crucial role in the initiation of periodontitis. However, the implications of P. gingivalis OMVs in the context of cardiovascular disease (CVD) remain incompletely understood. This study aimed to clarify both the impact and the underlying mechanisms through which P. gingivalis OMVs contribute to the propagation of distal cardiovascular inflammation and trauma.

METHODS

In this study, various concentrations (0, 1.25, 2.5, and 4.5 µg/µL) of P. gingivalis OMVs were microinjected into the common cardinal vein of zebrafish larvae at 48 h post-fertilization (hpf) to assess changes in cardiovascular injury and inflammatory response. Zebrafish larvae from both the PBS and the 2.5 µg/µL injection cohorts were harvested at 30 h post-injection (hpi) for transcriptional analysis. Real-time quantitative PCR (RT-qPCR) was employed to evaluate relative gene expression.

RESULTS

These findings demonstrated that P. gingivalis OMVs induced pericardial enlargement in zebrafish larvae, caused vascular damage, increased neutrophil counts, and activated inflammatory pathways. Transcriptomic analysis further revealed the involvement of the immune response and the extracellular matrix (ECM)-receptor interaction signaling pathway in this process.

CONCLUSION

This study illuminated potential mechanisms through which P. gingivalis OMVs contribute to CVD. It accentuated their involvement in distal cardiovascular inflammation and emphasizes the need for further research to comprehensively grasp the connection between periodontitis and CVD.

Establishing a Zebrafish Model for Borrelia burgdorferi Infection Using Immersion and Microinjection Methods

Borrelia burgdorferi is the spirochetal bacterium that causes Lyme disease. Even though antimicrobial sensitivity of B. burgdorferi has been widely studied, there is still a need to develop an affordable, practical, high-throughput in vivo model which can be used to find effective antibiotic therapies, especially for the recently discovered persister and biofilm forms. Here, we describe the immersion and microinjection methods to introduce B. burgdorferi spirochetes into zebrafish larvae. The B. burgdorferi-zebrafish model can be produced by immersing 5-day post-fertilization (dpf) zebrafish in a B. burgdorferi culture, or by injecting B. burgdorferi into the hindbrain of zebrafish at 28 h post-fertilization (hpf). To demonstrate that B. burgdorferi indeed infect the fish, nested polymerase chain reaction (PCR), reverse transcription PCR (RT-PCR), live fluorescence imaging, histological staining, and wholemount immunohistochemical (IHC) methods can be used on B. burgdorferi-infected zebrafish.

Targeted proteomics in a population-based study identifies serum PECAM-1 and TRIM21 as inflammation markers for periodontitis

OBJECTIVES

Periodontitis (PD) can cause systematic inflammation and is associated with various metabolic processes in the body. However, robust serum markers for these relationships are still lacking. This study aims to identify novel circulating inflammation-related proteins associated with PD using targeted proteomics.

MATERIALS AND METHODS

We used population-based, cross-sectional data from 619 participants of the Polish Longitudinal University Study (Bialystok PLUS). Mean pocket probing depth (mPPD) and proportion of bleeding on probing (pBOP) served as exposure variables. Fifty-two inflammation-related proteins were measured using the Olink Target 96 Cardiovascular III and the Olink Target 96 Immune Response panels. Associations between periodontal measures and proteins were tested using covariate-adjusted linear regression models.

RESULTS

At a false discovery rate of < 0.05, we identified associations of mPPD and pBOP with platelet-endothelial cell adhesion molecule-1 (PECAM-1) and tripartite motif-containing protein 21 (TRIM21).

CONCLUSION

This study revealed novel associations between PD and serum levels of PECAM-1 and TRIM21. Our results suggest that these proteins might be affected by molecular processes that take place in the inflamed periodontium.

CLINICAL RELEVANCE

Novel associations of PECAM-1 and TRIM21 with PD indicate promising serum markers for understanding the disease's pathophysiological processes and call for further biomedical investigations.

Endotoxin of Porphyromonas gingivalis amplifies the inflammatory response in hyperglycemia-induced zebrafish through a mechanism involving chitinase-like protein YKL-40 analogs

Porphyromonas gingivalis (P. gingivalis), a key pathogen in periodontal diseases, is also associated with hyperglycemia-associated systemic diseases, including diabetes mellitus (DM). Gingipains are the most important endotoxins of P. gingivalis, and in vivo studies using gingipains are scarce. Zebrafish (Danio rerio) is a vertebrate with high physiological and genetic homology with humans that has multiple co-orthologs for human genes, including inflammation-related proteins. The aim of our study was to determine the effects of gingipain in a hyperglycemia-induced zebrafish model by evaluating inflammation, oxidant-antioxidant status, and the cholinergic system. Adult zebrafish were grouped into the control group (C), hyperglycemia-induced group subjected to 15 days of overfeeding (OF), gingipain-injected group (GP), and gingipain-injected hyperglycemic group (OF + GP). At the end of 15 days, an oral glucose tolerance test (OGTT) was performed, and fasting blood glucose (FBG) levels were measured. Lipid peroxidation (LPO), nitric oxide (NO), glutathione (GSH), glutathione S-transferase, catalase, acetylcholinesterase (AChE), alkaline phosphatase (ALP), and sialic acid (SA) levels were determined spectrophotometrically in the hepatopancreas. The expression levels of tnf-⍺, il-1β, ins, crp, and the acute phase protein YKL-40 analogs chia.5 and chia.6 were evaluated by RT‒PCR. After two weeks of overfeeding, significantly increased weight gain, FBG, and OGTT confirmed that the zebrafish were hyperglycemic. Increased oxidative stress, inflammation, and AChE and ALP activities were observed in both the overfeeding and GP groups. Amplification of inflammation and oxidative stress was evident in the OF + GP group through increased expression of crp, il-1β, chia.5, and chia.6 and increased LPO and NO levels. Our results support the role of gingipains in the increased inflammatory response in hyperglycemia-associated diseases.

Interplay between Porphyromonas gingivalis Hemophore-Like Protein HmuY and Kgp/RgpA Gingipains Plays a Superior Role in Heme Supply

To acquire heme as a source of iron and protoporphyrin IX, Porphyromonas gingivalis uses gingipains, Hmu, and Hus systems. The aim of this study was to assess the correlation between the production and function of the most important virulence factors of P. gingivalis involved in heme supply, namely, hemophore-like proteins (HmuY and HusA) and gingipains. Respective mutant strains were used, and the expression of genes at the transcript and protein levels, as well as the importance of these genes' products for virulence potential, was examined. We found that HmuY and Kgp/RgpA gingipains are among the main P. gingivalis virulence factors synergistically engaged in heme supply. Their expression is related mainly when P. gingivalis grows in conditions rich in iron and heme sources, resembling those found in severe periodontitis. We confirmed that HmuY production is strictly dependent on the availability of heme and iron in the external environment, whereas we did not observe such dependence in the production of HusA. Moreover, we found that the HmuY protein can easily sequester heme from the HusA protein. The only correlation in the production of HmuY and HusA hemophore-like proteins could occur in P. gingivalis grown in conditions rich in iron and heme sources, mimicking an environment typical for severe periodontitis. Based on our observations, we suggest that HmuY is the major heme-binding protein produced by P. gingivalis, especially in iron- and heme-depleted conditions, typical for healthy periodontium and the initial stages of infection. The HusA protein could play a supporting role in P. gingivalis heme uptake. IMPORTANCE Altered or disturbed mutualism between oral microbiome members results in dysbiosis with local injuries and subsequently in systemic diseases. Periodontitis belongs to a group of multifactorial infectious diseases, characterized by inflammation and destruction of tooth-supporting tissues. Porphyromonas gingivalis is considered the main etiologic agent and keystone pathogen responsible for developing advanced periodontitis. As part of the infective process, P. gingivalis must acquire heme to survive and multiply at the infection site. Analysis of the mutual relationship between its main virulence factors showed that heme acquisition in P. gingivalis is a complex process in which mainly the Hmu system, with the leading role played by the HmuY hemophore-like protein, and Kgp and RgpA gingipains prefer cooperative interplay. It seems that the Hus system, including HusA hemophore-like protein, could be involved in another, so far uncharacterized, stage of iron and heme supply.

Zebrafish as model for studies in dentistry

INTRODUCTION

Over the last years, zebrafish has gained prominence in the biomedical community. It is currently considered one of the best vertebrate animal models for various types of studies, such as toxicology and developmental biology.

OBJECTIVE

The aim of this study was to conduct a literature review on the use of zebrafish in dentistry and whether this animal model could be a viable alternative for performing different types of studies in this area.

METHODS

A literature search was performed using the PubMed, Lilacs, Embase, and Dentistry and Oral Sciences Source. The keywords used as search terms were zebrafish and dentistry. The selection criteria were articles published in English that used zebrafish as an animal model in dentistry, oral health, and craniofacial growth/development.

RESULTS

The electronic search of literature yielded 421 articles. After the analysis of the abstracts, 29 articles were selected for an in-depth analysis and reading of the full text.

CONCLUSIONS

All studies included in this review confirm zebrafish's excellence as an animal model for various types of dentistry studies, as well as assisting and complementing other studies involving mammals.

Implications of Porphyromonas gingivalis peptidyl arginine deiminase and gingipain R in human health and diseases

Porphyromonas gingivalis is a major pathogenic bacterium involved in the pathogenesis of periodontitis. Citrullination has been reported as the underlying mechanism of the pathogenesis, which relies on the interplay between two virulence factors of the bacterium, namely gingipain R and the bacterial peptidyl arginine deiminase. Gingipain R cleaves host proteins to expose the C-terminal arginines for peptidyl arginine deiminase to citrullinate and generate citrullinated proteins. Apart from carrying out citrullination in the periodontium, the bacterium is found capable of citrullinating proteins present in the host synovial tissues, atherosclerotic plaques and neurons. Studies have suggested that both virulence factors are the key factors that trigger distal effects mediated by citrullination, leading to the development of some non-communicable diseases, such as rheumatoid arthritis, atherosclerosis, and Alzheimer’s disease. Thus, inhibition of these virulence factors not only can mitigate periodontitis, but also can provide new therapeutic solutions for systematic diseases involving bacterial citrullination. Herein, we described both these proteins in terms of their unique structural conformations and biological relevance to different human diseases. Moreover, investigations of inhibitory actions on the enzymes are also enumerated. New approaches for identifying inhibitors for peptidyl arginine deiminase through drug repurposing and virtual screening are also discussed.

Fusobacterium nucleatum mediates endothelial damage and increased permeability following single species and polymicrobial infection

BACKGROUND

Numerous lines of evidence link periodontal pathobionts and their virulence factors with endothelial damage. Most research has been conducted using single species infections at the exclusion of other periodontal microorganisms that have been identified in vascular tissue. Here, we assessed endothelial infection with either single or mixed periodontal species infection and examined their effect on endothelial damage and permeability.

METHODS

Cell surface abundance of platelet endothelial cell adhesion molecule-1 (PECAM-1) or endothelial permeability following infection with Porphyromonas gingivalis, Fusobacterium nucleatum subspecies (ssp) nucleatum, ssp polymorphum or Tannerella forsythia as single or mixed species infection was determined by flow cytometry and a fluorescent dextran permeability assay. Zebrafish embryos were infected systemically with either single or mixed species with mortality and disease measured over time.

RESULTS

F. nucleatum ssp nucleatum, ssp polymorphum and P. gingivalis significantly reduced PECAM-1 abundance in single species infection, whereas T. forsythia had no effect. F. nucleatum ssp polymorphum caused considerable mortality and morbidity in a zebrafish systemic infection model. Polymicrobial infection underscored the virulence of F. nucleatum ssp polymorphum in particular with increased endothelial cell death and reduced PECAM-1 abundance in co-infection studies with this organism. When injected systemically into zebrafish in polymicrobial infection, fluorescently labeled bacteria were distributed throughout the vasculature and cardiac region where, in some instances, they co-localized with each other.

CONCLUSIONS

These data provide further evidence on the effects of F. nucleatum on endothelium adhesion molecule abundance and permeability while also highlighting the importance of performing polymicrobial infection to study the molecular mechanisms associated with periodontal pathogen-induced vascular damage.

Modeling neurodegenerative disorders in zebrafish

Neurodegeneration is a major cause of Alzheimer's, Parkinson's, Huntington's, multiple and amyotrophic lateral sclerosis, pontocerebellar hypoplasia, dementia and other related brain disorders. Their complex pathogenesis commonly includes genetic and neurochemical deficits, misfolded protein toxicity, demyelination, apoptosis and mitochondrial dysfunctions. Albeit differing in specific underlying mechanisms, neurodegenerative disorders typically display evolutionarily conserved mechanisms across taxa. Here, we review the role of zebrafish models in recapitulating major human and rodent neurodegenerative conditions, demonstrating this species as a highly relevant experimental model for research on neurodegenerative diseases, and discussing how these fish models can further clarify the underlying genetic, neurochemical, neuroanatomical and behavioral pathogenic mechanisms.

Risk factors for bleeding after dental extractions in patients receiving antithrombotic drugs - A case control study

Background/purpose

Patients receiving antithrombotic drugs are more likely to suffer bleeding after tooth extraction and multiple factors are related to it. The aim of this study was to investigate the incidence of bleeding and risk factors for bleeding after dental extractions in patients receiving antithrombotic drugs.

Materials and methods

This retrospective case control study included patients receiving oral antithrombotic drugs or not. Tooth extractions were conducted under ECG monitoring and local hemostatic measures were performed. Risk factors for postoperative hemorrhage after tooth extraction were evaluated using univariate and multivariate analyses.

Results

Bleeding events were reported in 27 (27%) patients receiving antithrombotic drugs and 9 (9%) patients who didn't use antithrombotic drugs, the difference between which was significant (p < 0.01). Univariate analyses showed that age (OR = 2.717, p = 0.028), oral hygiene (OR = 4.110, p = 0.043), inferior nerve block (OR = 4.285, p = 0.038) and number of extracted tooth (OR = 4.758, p = 0.029) were significantly correlate with bleeding incidence. Multivariate analysis revealed that age (OR = 2.824, p = 0.036) and number of extracted tooth (OR = 5.268, p = 0.016) were significant risk factors for postextraction bleeding.

Conclusion

The results suggest that there is higher incidence of postextraction bleeding in patients receiving antithrombotic drugs compared to patients who don't. Age (>75 years), oral hygiene, inferior nerve block and number of extracted tooth may be related to bleeding after tooth extraction.

Mechanisms of vascular damage by systemic dissemination of the oral pathogen Porphyromonas gingivalis

Several studies have shown a clear association between periodontal disease and increased risk of cardiovascular disease. Porphyromonas gingivalis (Pg), a key oral pathogen, and its cell surface-expressed gingipains, induce oedema in a zebrafish larvae infection model although the mechanism of these vascular effects is unknown. Here, we aimed to determine whether Pg-induced vascular damage is mediated by gingipains. In vitro, human endothelial cells from different vascular beds were invaded by wild-type (W83) but not gingipain-deficient (ΔK/R-ab) Pg. W83 infection resulted in increased endothelial permeability as well as decreased cell surface abundance of endothelial adhesion molecules PECAM-1 and VE-cadherin compared to infection with ΔK/R-ab. In agreement, when transgenic zebrafish larvae expressing fluorescently labelled PECAM-1 or VE-cadherin were systemically infected with W83 or ΔK/R-ab, a significant reduction in adhesion molecule fluorescence was observed specifically in endothelium proximal to W83 bacteria through a gingipain-dependent mechanism. Furthermore, this was associated with increased vascular permeability in vivo when assessed by dextran leakage microangiography. These data are the first to show that Pg directly mediates vascular damage in vivo by degrading PECAM-1 and VE-cadherin. Our data provide a molecular mechanism by which Pg might contribute to cardiovascular disease.

Porphyromonas gingivalis Outer Membrane Vesicles Increase Vascular Permeability

Periodontitis is increasingly associated with increased risk of cardiovascular and other systemic diseases. The Gram-negative anaerobe, Porphyromonas gingivalis, is a key periodontal pathogen, and several lines of evidence link the presence of this bacterium in the circulation with vascular disease. The outer membrane vesicles (OMVs) produced by P. gingivalis have been shown to play a role in periodontitis, although, to date, little is known about their interaction with the vasculature; therefore, this study assessed the effects of P. gingivalis OMVs on the endothelium. OMVs were isolated from wild-type strain W83 and the gingipain-deficient strain ΔK/R-ab. Immunoblotting along with cryo-EM showed gingipain expression in W83 but not ΔK/R-ab-derived OMVs, where gingipains were localized to the cell wall surface. Confluent endothelial cell monolayers infected with either W83 or W83-derived OMV displayed significantly increased dextran permeability over those infected with ΔK/R-ab or its OMV. Moreover, W83-derived OMVs induced significantly more vascular disease in a zebrafish larvae systemic infection model over 72 h compared to those injected with gingipain-deficient OMVs or controls. In line with these data, human microvascular endothelial cells (HMEC-1) displayed an OMV-associated, gingipain-dependent decrease in cell surface levels of the intercellular adhesion molecule PECAM-1 (CD31) when examined by flow cytometry. These data show, for the first time, that OMVs from P. gingivalis mediate increased vascular permeability, leading to a diseased phenotype both in vitro and in vivo. Moreover, these data strongly implicate gingipains present on the OMV surface in mediating these vascular events, most likely via a mechanism that involves proteolytic cleavage of endothelial cell-cell adhesins such as PECAM-1. These data provide important evidence for the role of bacterial-derived OMVs in mediating systemic disease.

Oral bacteria and leaky endothelial junctions in remote extraoral sites

Periodontitis and periodontal pathogens have been associated with systemic complications that influence comorbid conditions, such as cardiovascular disease. Using a zebrafish larvae infection model, Farrugia et al. show that Porphyromonas gingivalis causes vascular damage and increased endothelial permeability by degrading, via its gingipain proteases, platelet endothelial cell adhesion molecule-1, and vascular endothelial cadherin, which are crucial for endothelial junctional integrity. These findings suggest a molecular mechanism whereby this oral pathogen may contribute to endothelial dysfunction and perhaps atherosclerotic cardiovascular disease.

[Research progress of correlation between periodontal pathogens and systemic diseases]

Periodontal pathogens are the main pathogenic factor of periodontitis. Periodontal pathogens have a large variety of virulence factors such as lipopolysaccharide, fimbriae and proteases, which enables the pathogens to infect periodontal tissues and stimulate the secretion of inflammatory cytokines, causing chronic systemic inflammation. Periodontal pathogens may invade multiple systems such as the circulatory system, immune system, respiratory system and digestive system to cause systematic diseases. Recent studies have shown that periodontal pathogens may have close relations with systemic diseases such as cardiovascular disease, diabetes, rheumatoid arthritis, and cancer. Among the periodontal pathogens, Porphyromonas gingivalis can be found in atherosclerotic plaques to impairing the function of the vascular endothelium; Porphyromonas gingivalis may also increase the level of inflammatory factors such as TNF-α to promote insulin resistance and diabetes. Many of the periodontal pathogens such as Porphyromonas gingivalis, Tannerella forsythia and Prevotella intermedia can be detected in the synovial fluid of rheumatoid arthritis patients, suggesting their involvement in the pathogenesis of rheumatoid arthritis. Fusobacterium nucleatum may cause alterations in the intestinal microbiome in mice and promote the occurrence of intestinal tumors. Herein we review the recent progresses in the relationship between periodontal pathogens and systemic diseases.

Identification of Novel Bacteriophages with Therapeutic Potential That Target Enterococcus faecalis

The Gram-positive opportunistic pathogen Enterococcus faecalis is frequently responsible for nosocomial infections in humans and represents one of the most common bacteria isolated from recalcitrant endodontic (root canal) infections. E. faecalis is intrinsically resistant to several antibiotics routinely used in clinical settings (such as cephalosporins and aminoglycosides) and can acquire resistance to vancomycin (vancomycin-resistant enterococci). The resistance of E. faecalis to several classes of antibiotics and its capacity to form biofilms cause serious therapeutic problems. Here, we report the isolation of several bacteriophages that target E. faecalis strains isolated from the oral cavity of patients suffering root canal infections. All phages isolated were Siphoviridae with similar tail lengths (200 to 250 nm) and icosahedral heads. The genome sequences of three isolated phages were highly conserved with the exception of predicted tail protein genes that diverge in sequence, potentially reflecting the host range. The properties of the phage with the broadest host range (SHEF2) were further characterized. We show that this phage requires interaction with components of the major and variant region enterococcal polysaccharide antigen to engage in lytic infection. Finally, we explored the therapeutic potential of this phage and show that it can eradicate E. faecalis biofilms formed in vitro on a standard polystyrene surface but also on a cross-sectional tooth slice model of endodontic infection. We also show that SHEF2 cleared a lethal infection of zebrafish when applied in the circulation. We therefore propose that the phage described here could be used to treat a broad range of antibiotic-resistant E. faecalis infections.

Candidalysin Is Required for Neutrophil Recruitment and Virulence During Systemic Candida albicans Infection

BACKGROUND

Candidalysin is a cytolytic peptide toxin secreted by Candida albicans hyphae and has significantly advanced our understanding of fungal pathogenesis. Candidalysin is critical for mucosal C albicans infections and is known to activate epithelial cells to induce downstream innate immune responses that are associated with protection or immunopathology during oral or vaginal infections. Furthermore, candidalysin activates the NLRP3 inflammasome and causes cytolysis in mononuclear phagocytes. However, the role of candidalysin in driving systemic infections is unknown.

METHODS

In this study, using candidalysin-producing and candidalysin-deficient C albicans strains, we show that candidalysin activates mitogen-activated protein kinase (MAPK) signaling and chemokine secretion in endothelial cells in vitro.

RESULTS

Candidalysin induces immune activation and neutrophil recruitment in vivo, and it promotes mortality in zebrafish and murine models of systemic fungal infection.

CONCLUSIONS

The data demonstrate a key role for candidalysin in neutrophil recruitment and fungal virulence during disseminated systemic C albicans infections.

Hydroxycholesterol binds and enhances the anti-viral activities of zebrafish monomeric c-reactive protein isoforms

C-reactive proteins (CRPs) are among the faster acute-phase inflammation-responses proteins encoded by one gene (hcrp) in humans and seven genes (crp1-7) in zebrafish (Danio rerio) with importance in bacterial and viral infections. In this study, we described novel preferential bindings of 25-hydroxycholesterol (25HOCh) to CRP1-7 compared with other lipids and explored the antiviral effects of both 25HOCh and CRP1-7 against spring viremia carp virus (SVCV) infection in zebrafish. Both in silico and in vitro results confirmed the antiviral effect of 25HOCh and CRP1-7 interactions, thereby showing that the crosstalk between them differed among the zebrafish isoforms. The presence of oxidized cholesterols in human atherosclerotic plaques amplifies the importance that similar interactions may occur for vascular and/or neurodegenerative diseases during viral infections. In this context, the zebrafish model offers a genetic tool to further investigate these interactions.

Cold-Shock Domain Family Proteins (Csps) Are Involved in Regulation of Virulence, Cellular Aggregation, and Flagella-Based Motility in Listeria monocytogenes

Cold shock-domain family proteins (Csps) are highly conserved nucleic acid binding proteins regulating the expression of various genes including those involved in stress resistance and virulence in bacteria. We show here that Csps are involved in virulence, cell aggregation and flagella-based extracellular motility of Listeria monocytogenes. A L. monocytogenes mutant deleted in all three csp genes (ΔcspABD) is attenuated with respect to human macrophage infection as well as virulence in a zebrafish infection model. Moreover, this mutant is incapable of aggregation and fails to express surface flagella or exhibit swarming motility. An evaluation of double csp gene deletion mutant (ΔcspBD, ΔcspAD and ΔcspAB) strains that produce single csp genes showed that there is redundancy as well as functional differences among the three L. monocytogenes Csps in their contributions to virulence, cellular aggregation, flagella production, and swarming motility. Protein and mRNA expression analysis further showed impaired expression of key virulence and motility genes in the csp mutants. Our observations at protein and mRNA level suggest Csp-dependent expression regulation of these genes at transcriptional and post-transcriptional levels. In a mutant lacking all csp genes (ΔcspABD) as well as those possessing single csp genes (ΔcspBD, ΔcspAD, and ΔcspAB) we detected reduced levels of proteins or activity as well as transcripts from the prfA, hly, mpl, and plcA genes suggesting a Csp-dependent transcriptional regulation of these genes. These csp mutants also had reduced or completely lacked ActA proteins and cell surface flagella but contained elevated actA and flaA mRNA levels compared to the parental wild type strain suggesting Csp involvement in post-transcriptional regulation of these genes. Overall, our results suggest that Csps contribute to the expression regulation of virulence and flagella-associated genes thereby promoting host pathogenicity, cell aggregation and flagella-based motility processes in L. monocytogenes.