Characterization of a novel family of fibronectin-binding proteins with M23 peptidase domains from Treponema denticola

Leptospiral cell wall hydrolase (LIC_10271) binding peptidoglycan, lipopolysaccharide, and laminin and the protein show LysM and M23 domains are co-existing in pathogenic species

Leptospirosis, a global reemerging zoonosis caused by the spirochete Leptospira, has severe human and veterinary implications. Cell wall hydrolase (LIC_10271) with LytM (peptidase M23) and LysM domains are found to be associated with various pathogenic bacteria. These domains regulate effects on extracellular matrix and biofilm components, which promote cell wall remodeling and pathogen dissemination in the host. In this study, we present the cloning, expression, purification, and characterization of LIC_10271. To determine the localization of LIC_10271 within the inner membrane of Leptospira, Triton X-114 subcellular fractionation and immunoblot studies were performed. Furthermore, r-LIC_10271 binds with peptidoglycan, lipopolysaccharide, and laminin in a dose-dependent manner. Analysis of the signal peptide, M23, and LysM domains revealed conservation primarily within the P1 group of Leptospira, which encompasses the most pathogenic species. Moreover, the presence of native-LIC_10271 in the inner membrane and the distribution of M23 and LysM domains across pathogenic strains indicates their potential involvement in the interaction between the host and Leptospira.

Syphilis vaccine: challenges, controversies and opportunities

Syphilis is a sexually or vertically (mother to fetus) transmitted disease caused by the infection of Treponema pallidum subspecie pallidum (TPA). The incidence of syphilis has increased over the past years despite the fact that this bacterium is an obligate human pathogen, the infection route is well known, and the disease can be successfully treated with penicillin. As complementary measures to preventive campaigns and early treatment of infected individuals, development of a syphilis vaccine may be crucial for controlling disease spread and/or severity, particularly in countries where the effectiveness of the aforementioned measures is limited. In the last century, several vaccine prototypes have been tested in preclinical studies, mainly in rabbits. While none of them provided protection against infection, some prototypes prevented bacteria from disseminating to distal organs, attenuated lesion development, and accelerated their healing. In spite of these promising results, there is still some controversy regarding the identification of vaccine candidates and the characteristics of a syphilis-protective immune response. In this review, we describe what is known about TPA immune response, and the main mechanisms used by this pathogen to evade it. Moreover, we emphasize the importance of integrating this knowledge, in conjunction with the characterization of outer membrane proteins (OMPs), to expedite the development of a syphilis vaccine that can protect against TPA infection.

One fold, many functions-M23 family of peptidoglycan hydrolases

Bacterial cell walls are the guards of cell integrity. They are composed of peptidoglycan that provides rigidity to sustain internal turgor and ensures isolation from the external environment. In addition, they harbor the enzymatic machinery to secure cell wall modulations needed throughout the bacterial lifespan. The main players in this process are peptidoglycan hydrolases, a large group of enzymes with diverse specificities and different mechanisms of action. They are commonly, but not exclusively, found in prokaryotes. Although in most cases, these enzymes share the same molecular function, namely peptidoglycan hydrolysis, they are leveraged to perform a variety of physiological roles. A well-investigated family of peptidoglycan hydrolases is M23 peptidases, which display a very conserved fold, but their spectrum of lytic action is broad and includes both Gram- positive and Gram- negative bacteria. In this review, we summarize the structural, biochemical, and functional studies concerning the M23 family of peptidases based on literature and complement this knowledge by performing large-scale analyses of available protein sequences. This review has led us to gain new insight into the role of surface charge in the activity of this group of enzymes. We present relevant conclusions drawn from the analysis of available structures and indicate the main structural features that play a crucial role in specificity determination and mechanisms of latency. Our work systematizes the knowledge of the M23 family enzymes in the context of their unique antimicrobial potential against drug-resistant pathogens and presents possibilities to modulate and engineer their features to develop perfect antibacterial weapons.

Structural insight into protein-protein interactions between intestinal microbiome and host

Protein-protein interactions between the microbiome and host organism play an important role in shaping host health. These host-modulating proteins have therapeutic potential in treating microbiome-linked disorders such as inflammatory bowel disease and obesity. Structural analysis of interacting proteins provides highly mechanistic insight into the domains driving these interactions and the resulting influence on host cell processes. Here, we briefly review recent publication of microbiome protein structures involved in host binding interactions, the effects of these interactions on host physiology, and the need for further study to increase the ability to detect proteins with therapeutic potential.

Crawling motility of Treponema denticola modulated by outer sheath protein

Treponema denticola, a helically shaped motile microorganism, is a major pathogen of chronic periodontitis. Major surface protein (Msp) and dentilisin are virulence factors of T. denticola that are located on the outer sheath. The motility of T. denticola is deeply involved in colonization on and invasion into the host tissue. The outer sheath is located at the interface between the environment and T. denticola, and its components may also contribute to its motility via interaction with the materials outside the cells. The study aimed to clarify whether Msp or dentilisin contributes to the motility of T. denticola on solid surfaces, termed crawling, by investigating their effects using Msp-deficient and dentilisin-deficient T. denticola strains. Motility was analyzed by measuring the colony size in agar plates and velocity was analyzed using dark-field microscopy. The colony area of the mutant strains was smaller than that of the wild-type strain. The crawling velocity of the mutant strains was lower than that of the wild-type strain, with the lowest velocity observed in the dentilisin-deficient strain. Additionally, the ratio of the crawling distance by one revolution to the protoplasmic cylinder pitch (an indicator of the crawling efficiency) in the dentilisin mutant was significantly lower than that in the wild type strain and the Msp mutant. Together, these results indicate that dentilisin facilitates the crawling-dependent surface spreading of T. denticola.

MMPphg from the thermophilic Meiothermus bacteriophage MMP17 as a potential antimicrobial agent against both Gram-negative and Gram-positive bacteria

Background

New strategies are urgently needed to deal with the growing problem of multidrug-resistant bacterial pathogens. As the natural viruses against bacteria, recently, bacteriophages have received particular attention. Here, we identified and characterized a novel peptidoglycan hydrolase named MMPphg by decoding the complete genome sequence of Meiothermus bacteriophage MMP17, which was isolated in Tengchong hot spring in China and contains a circular genome of 33,172 bp in size and a GC content of 63.4%.

Findings

We cloned the MMPphg gene, overproduced and purified the phage lytic protein, which contains a highly conserved M23 metallopeptidase domain and can be activated by Mg²⁺ and Zn²⁺. MMPphg is capable of withstanding temperatures up to 70 °C, and preserved more than 80% of its activity after a 30 min treatment between 35 and 65 °C. More interestingly, by disrupting bacterial cells, MMPphg exhibits surprising antimicrobial activity against both Gram-negative and Gram-positive pathogenic bacteria, especially antibiotic-resistant strains such as Escherichia coli O157, Staphylococcus aureus and Klebsiella pneumonia.

Conclusions

In the current age of mounting antibiotic resistance, these results suggest the great potential of MMPphg, the gene product of bacteriophage MMP17, in combating bacterial infections and shed light on bacteriophage-based strategies to develop alternatives to conventional antibiotics for human or veterinary applications.

Oral spirochetes: Pathogenic mechanisms in periodontal disease

Periodontitis is an infectious inflammatory disease resulting from infection of biofilm forming bacteria. Several bacterial factors regulate inflammatory response and cause to tissue damage and loss of connection between gingival and tooth. Since bacterial virulence factors and also host immune responses have role, understanding of periodontal disease is complex, in overall we can say that in this disease epithelium is deleted by bacteria. Oral spirochetes are related to periodontitis, among them, Treponema denticola, have been associated with periodontal diseases such as early-onset periodontitis, necrotizing ulcerative gingivitis, and acute pericoronitis. This review will analyse mechanisms of pathogenesis of spirochetes in periodontitis. Microorganisms cause destruction of gingival tissue by two mechanisms. In one, damage results from the direct action of bacterial enzymes and cytotoxic products of bacterial metabolism. In the other, only bacterial components have role, and tissue destruction is the inevitable side effect of a subverted and exaggerated host inflammatory response to plaque antigens.

Genome Investigation of a Cariogenic Pathogen with Implications in Cardiovascular Diseases

The proportion of people suffering from cardiovascular diseases has risen by 34% in the last 15 years in India. Cardiomyopathy is among the many forms of CVD s present. Infection of heart muscles is the suspected etiological agent for the same. Oral pathogens gaining entry into the bloodstream are responsible for such infections. Streptococcus mutans is an oral pathogen with implications in cardiovascular diseases. Previous studies have shown certain strains of S. mutans are found predominantly within atherosclerotic plaques and extirpated valves. To decipher the genetic differences responsible for endothelial cell invasion, we have sequenced the genome of Streptococcus mutans B14. Pan-genome analysis, search for adhesion proteins through a special algorithm, and protein-protein interactions search through HPIDB have been done. Pan-genome analysis of 187 whole genomes, assemblies revealed 6965 genes in total and 918 genes forming the core gene cluster. Adhesion to the endothelial cell is a critical virulence factor distinguishing virulent and non-virulent strains. Overall, 4% of the total proteins in S. mutans B14 were categorized as adhesion proteins. Protein-protein interaction between putative adhesion proteins and Human extracellular matrix components was predicted, revealing novel interactions. A conserved gene catalyzing the synthesis of branched-chain amino acids in S. mutans B14 shows possible interaction with isoforms of cathepsin protein of the ECM. This genome sequence analysis indicates towards other proteins in the S. mutans genome, which might have a specific role to play in host cell interaction.

Novel Treponema pallidum Recombinant Antigens for Syphilis Diagnostics: Current Status and Future Prospects

The recombinant protein technology considerably promoted the development of rapid and accurate treponema-specific laboratory diagnostics of syphilis infection. For the last ten years, the immunodominant recombinant inner membrane lipoproteins are proved to be sensitive and specific antigens for syphilis screening. However, the development of an enlarged T. pallidum antigen panel for diagnostics of early and late syphilis and differentiation of syphilis stages or cured syphilis remains as actual goal of multidisciplinary expertise. Current review revealed novel recombinant antigens: surface-exposed proteins, adhesins, and periplasmic and flagellar proteins, which are promising candidates for the improved syphilis serological diagnostics. The opportunities and limitations of diagnostic usage of these antigens are discussed and the criteria for selection of optimal antigens panel summarized.

The Adhesion of Lactobacillus salivarius REN to a Human Intestinal Epithelial Cell Line Requires S-layer Proteins

Lactobacillus salivarius REN, a novel probiotic isolated from Chinese centenarians, can adhere to intestinal epithelial cells and subsequently colonize the host. We show here that the surface-layer protein choline-binding protein A (CbpA) of L. salivarius REN was involved in adherence to the human colorectal adenocarcinoma cell line HT-29. Adhesion of a cbpA deletion mutant was significantly reduced compared with that of wild-type, suggesting that CbpA acts as an adhesin that mediates the interaction between the bacterium and its host. To identify the molecular mechanism of adhesion, we determined the crystal structure of a truncated form of CbpA that is likely involved in binding to its cell-surface receptor. The crystal structure identified CbpA as a peptidase of the M23 family whose members harbor a zinc-dependent catalytic site. Therefore, we propose that CbpA acts as a multifunctional surface protein that cleaves the host extracellular matrix and participates in adherence. Moreover, we identified enolase as the CbpA receptor on the surface of HT-29 cells. The present study reveals a new class of surface-layer proteins as well as the molecular mechanism that may contribute to the ability of L. salivarius REN to colonize the human gut.

The Adhesion of Lactobacillus salivarius REN to a Human Intestinal Epithelial Cell Line Requires S-layer Proteins

Lactobacillus salivarius REN, a novel probiotic isolated from Chinese centenarians, can adhere to intestinal epithelial cells and subsequently colonize the host. We show here that the surface-layer protein choline-binding protein A (CbpA) of L. salivarius REN was involved in adherence to the human colorectal adenocarcinoma cell line HT-29. Adhesion of a cbpA deletion mutant was significantly reduced compared with that of wild-type, suggesting that CbpA acts as an adhesin that mediates the interaction between the bacterium and its host. To identify the molecular mechanism of adhesion, we determined the crystal structure of a truncated form of CbpA that is likely involved in binding to its cell-surface receptor. The crystal structure identified CbpA as a peptidase of the M23 family whose members harbor a zinc-dependent catalytic site. Therefore, we propose that CbpA acts as a multifunctional surface protein that cleaves the host extracellular matrix and participates in adherence. Moreover, we identified enolase as the CbpA receptor on the surface of HT-29 cells. The present study reveals a new class of surface-layer proteins as well as the molecular mechanism that may contribute to the ability of L. salivarius REN to colonize the human gut.

Identification and classification of known and putative antimicrobial compounds produced by a wide variety of Bacillales species

BACKGROUND

Gram-positive bacteria of the Bacillales are important producers of antimicrobial compounds that might be utilized for medical, food or agricultural applications. Thanks to the wide availability of whole genome sequence data and the development of specific genome mining tools, novel antimicrobial compounds, either ribosomally- or non-ribosomally produced, of various Bacillales species can be predicted and classified. Here, we provide a classification scheme of known and putative antimicrobial compounds in the specific context of Bacillales species.

RESULTS

We identify and describe known and putative bacteriocins, non-ribosomally synthesized peptides (NRPs), polyketides (PKs) and other antimicrobials from 328 whole-genome sequenced strains of 57 species of Bacillales by using web based genome-mining prediction tools. We provide a classification scheme for these bacteriocins, update the findings of NRPs and PKs and investigate their characteristics and suitability for biocontrol by describing per class their genetic organization and structure. Moreover, we highlight the potential of several known and novel antimicrobials from various species of Bacillales.

CONCLUSIONS

Our extended classification of antimicrobial compounds demonstrates that Bacillales provide a rich source of novel antimicrobials that can now readily be tapped experimentally, since many new gene clusters are identified.

Muscle- and Skin-Derived Cues Jointly Orchestrate Patterning of Somatosensory Dendrites

Sensory dendrite arbors are patterned through cell-autonomously and non-cell-autonomously functioning factors [1-3]. Yet, only a few non-cell-autonomously acting proteins have been identified, including semaphorins [4, 5], brain-derived neurotrophic factors (BDNFs) [6], UNC-6/Netrin [7], and the conserved MNR-1/Menorin-SAX-7/L1CAM cell adhesion complex [8, 9]. This complex acts from the skin to pattern the stereotypic dendritic arbors of PVD and FLP somatosensory neurons in Caenorhabditis elegans through the leucine-rich transmembrane receptor DMA-1/LRR-TM expressed on PVD neurons [8, 9]. Here we describe a role for the diffusible C. elegans protein LECT-2, which is homologous to vertebrate leukocyte cell-derived chemotaxin 2 (LECT2)/Chondromodulin II. LECT2/Chondromodulin II has been implicated in a variety of pathological conditions [10-13], but the developmental functions of LECT2 have remained elusive. We find that LECT-2/Chondromodulin II is required for development of PVD and FLP dendritic arbors and can act as a diffusible cue from a distance to shape dendritic arbors. Expressed in body-wall muscles, LECT-2 decorates neuronal processes and hypodermal cells in a pattern similar to the cell adhesion molecule SAX-7/L1CAM. LECT-2 functions genetically downstream of the MNR-1/Menorin-SAX-7/L1CAM adhesion complex and upstream of the DMA-1 receptor. LECT-2 localization is dependent on SAX-7/L1CAM, but not on MNR-1/Menorin or DMA-1/LRR-TM, suggesting that LECT-2 functions as part of the skin-derived MNR-1/Menorin-SAX-7/L1CAM adhesion complex. Collectively, our findings suggest that LECT-2/Chondromodulin II acts as a muscle-derived, diffusible cofactor together with a skin-derived cell adhesion complex to orchestrate the molecular interactions of three tissues during patterning of somatosensory dendrites.

Fibronectin-binding protein TDE1579 affects cytotoxicity of Treponema denticola

While FbpA, a family of bacterial fibronectin (FN) binding proteins has been studied in several gram-positive bacteria, the gram-negative Treponema denticola, an anaerobic periodontal pathogen, also has an overlooked fbp gene (tde1579). In this research, we confirm that recombinant Fbp protein (rFbp) of T. denticola binds human FN with a Kdapp of 1.5 × 10(-7) M and blocks the binding of T. denticola to FN in a concentration-dependent manner to a level of 42%. The fbp gene was expressed in T. denticola. To reveal the roles of fbp in T. denticola pathogenesis, an fbp isogenic mutant was constructed. The fbp mutant had 51% reduced binding ability to human gingival fibroblasts (hGF). When hGF were challenged with T. denticola, the fbp mutant caused less cell morphology change, had 50% reduced cytotoxicity to hGF, and had less influence on the growth of hGF cells.

That's my story, and I'm sticking to it--an update on B. burgdorferi adhesins

Adhesion is the initial event in the establishment of any infection. Borrelia burgdorferi, the etiological agent of Lyme disease, possesses myriad proteins termed adhesins that facilitate contact with its vertebrate hosts. B. burgdorferi adheres to host tissues through interactions with host cells and extracellular matrix, as well as other molecules present in serum and extracellular fluids. These interactions, both general and specific, are critical in the establishment of infection. Modulation of borrelial adhesion to host tissues affects the microorganisms's ability to colonize, disseminate, and persist. In this review, we update the current knowledge on structure, function, and role in pathogenesis of these “sticky” B. burgdorferi infection-associated proteins.

Leukocyte cell-derived chemotaxin 2 antagonizes MET receptor activation to suppress hepatocellular carcinoma vascular invasion by protein tyrosine phosphatase 1B recruitment

Leukocyte cell-derived chemotoxin 2 (LECT2) has been shown to act as a tumor suppressor in hepatocellular carcinoma (HCC). However, the underlying mechanism has not yet been completely defined. Here, we employ a LECT2-affinity column plus liquid chromatography coupled with tandem mass spectrometry to identify LECT2-binding proteins and found that MET receptor strongly interacted with LECT2 protein. Despite the presence of hepatocyte growth factor, the LECT2 binding causes an antagonistic effect to MET receptor activation through recruitment of protein tyrosine phosphatase 1B. The antagonistic effect of LECT2 on MET activation also mainly contributes to the blockage of vascular invasion and metastasis of HCC. Furthermore, serial deletions and mutations of LECT2 showed that the HxGxD motif is primarily responsible for MET receptor binding and its antagonistic effects.

CONCLUSION

These findings reveal a novel, specific inhibitory function of LECT2 in HCC by the direct binding and inactivation of MET, opening a potential avenue for treating MET-related liver cancer.

Major membrane protein TDE2508 regulates adhesive potency in Treponema denticola

The cultivation and genetic manipulation of Treponema denticola, a Gram-negative oral spirochaeta associated with periodontal diseases, is still challenging. In this study, we formulated a simple medium based on a commercially available one, and established a transformation method with high efficiency. We then analyzed proteins in a membrane fraction in T. denticola and identified 16 major membrane-associated proteins, and characterized one of them, TDE2508, whose biological function was not yet known. Although this protein, which exhibited a complex conformation, was presumably localized in the outer membrane, we did not find conclusive evidence that it was exposed on the cell surface. Intriguingly, a TDE2508-deficient mutant exhibited significantly increased biofilm formation and adherent activity on human gingival epithelial cells. However, the protein deficiency did not alter autoaggregation, coaggregation with Porphyromonas gingivalis, hemagglutination, cell surface hydrophobicity, motility, or expression of Msp which was reported to be an adherent molecule in this bacteria. In conclusion, the major membrane protein TDE2508 regulates biofilm formation and the adhesive potency of T. denticola, although the underlying mechanism remains unclear.

Comparative proteomic label-free analysis of Campylobacter jejuni NCTC 11168 cultured with porcine mucin

Campylobacter jejuni is a major gastrointestinal pathogen in humans. Poultry is a primary reservoir for C. jejuni, and C. jejuni appears to be highly adapted to the gastrointestinal tracts of avian species. We determined the protein expression profiles of C. jejuni NCTC 11168 cultured in medium containing porcine mucin. Differentially expressed proteins in the presence and absence of porcine mucin were identified using the label-free method. We identified 52 proteins with expression that was either upregulated (32 proteins) or downregulated (20 proteins) by porcine mucin. These proteins are involved in diverse cellular functions, such as motility, cell wall synthesis, iron transport, energy production, and amino acid metabolism. In particular, the upregulated proteins were involved in chemotaxis (CheV and CetA), motility (FlaA), colonization and adherence (CadF, FrdA, CfrA, MapA, and HydA), and stress tolerance (TrxB and ClpB). These results suggest that C. jejuni changes its protein expression in response to porcine mucin and that this change in expression may contribute to host adaptation of C. jejuni NCTC 11168.

The effects of different orthodontic appliances upon microbial communities

OBJECTIVES

Orthodontic appliances can promote accumulation of dental plaque, with associated enamel decalcification or gingival inflammation. The aim of this study was to examine longer-term microbiological changes during orthodontic treatment with fixed appliances.

MATERIALS AND METHODS

Twenty-four orthodontic patients aged 11-14 years undergoing fixed appliance therapy were recruited into the study. Each was randomized for cross-mouth assignment of molar bands and bonded molar tubes to contralateral quadrants of the mouth. All patients received self-ligating brackets, but again using randomization, one upper lateral incisor bracket (left or right) also received an elastomeric ligature. Plaque samples from the molars and upper lateral incisors were obtained at intervals during treatment and up to 1 year after appliance removal. Denaturing gradient gel electrophoresis and 16S rDNA microarray were used to compare plaque microbial fingerprints.

RESULTS

Plaque populations changed within 3 months of commencing treatment at all sites. The greatest differences in plaque composition were seen with self-ligating brackets with an elastomeric ligature. Post-treatment plaque associated with both types of molar attachment contained increased levels of periodontal pathogens Porphyromonas gingivalis, Tannerella forsythia, and Eubacterium nodatum, while Campylobacter rectus, Parvimonas micra, and Actinomyces odontolyticus were also elevated with bonds.

CONCLUSIONS

The results suggest that orthodontic treatment may cause sustained changes in plaque microbiotas and that molar bond-associated plaque may have raised disease potential.

Immunoproteomic analysis of proteins expressed by two related pathogens, Burkholderia multivorans and Burkholderia cenocepacia, during human infection

Burkholderia cepacia complex (Bcc) is an opportunistic bacterial pathogen that causes chronic infections in people with cystic fibrosis (CF). It is a highly antibiotic resistant organism and Bcc infections are rarely cleared from patients, once they are colonized. The two most clinically relevant species within Bcc are Burkholderia cenocepacia and Burkholderia multivorans. The virulence of these pathogens has not been fully elucidated and the virulence proteins expressed during human infection have not been identified to date. Furthermore, given its antibiotic resistance, prevention of infection with a prophylactic vaccine may represent a better alternative than eradication of an existing infection. We have compared the immunoproteome of two strains each from these two species of Bcc, with the aim of identifying immunogenic proteins which are common to both species. Fourteen immunoreactive proteins were exclusive to both B. cenocepacia strains, while 15 were exclusive to B. multivorans. A total of 15 proteins were immunogenic across both species. DNA-directed RNA polymerase, GroEL, 38kDa porin and elongation factor-Tu were immunoreactive proteins expressed by all four strains examined. Many proteins which were immunoreactive in both species, warrant further investigations in order to aid in the elucidation of the mechanisms of pathogenesis of this difficult organism. In addition, identification of some of these could also allow the development of protective vaccines which may prevent colonisation.

Treponema denticola interactions with host proteins

Oral Treponema species, most notably T. denticola, are implicated in the destructive effects of human periodontal disease. Progress in the molecular analysis of interactions between T. denticola and host proteins is reviewed here, with particular emphasis on the characterization of surface-expressed and secreted proteins of T. denticola involved in interactions with host cells, extracellular matrix components, and components of the innate immune system.

Periodontal pathogens affect the level of protease inhibitors in gingival crevicular fluid

In periodontitis, an effective host-response is primarily related to neutrophils loaded with serine proteases, including elastase (NE) and protease 3 (PR3), the extracellular activity of which is tightly controlled by endogenous inhibitors. In vitro these inhibitors are degraded by gingipains, cysteine proteases produced by Porphyromonas gingivalis. The purpose of this study was to determine the level of selected protease inhibitors in gingival crevicular fluid (GCF) in relation to periodontal infection. The GCF collected from 31 subjects (nine healthy controls, seven with gingivitis, five with aggressive periodontitis and 10 with chronic periodontitis) was analyzed for the levels of elafin and secretory leukocyte protease inhibitor (SLPI), two main tissue-derived inhibitors of neutrophil serine proteases. In parallel, activity of NE, PR3 and arginine-specific gingipains (Rgps) in GCF was measured. Finally loads of P. gingivalis, Aggregatibacter actinomycetemcomitans, Tannerella forsythia and Treponema denticola were determined. The highest values of elafin were found in aggressive periodontitis and the lowest in controls. The quantity of elafin correlated positively with the load of P. gingivalis, Ta. forsythia and Tr. denticola, as well as with Rgps activity. In addition, NE activity was positively associated with the counts of those bacterial species, but not with the amount of elafin. In contrast, the highest concentrations of SLPI were found in periodontally healthy subjects whereas amounts of this inhibitor were significantly decreased in patients infected with P. gingivalis. Periodontopathogenic bacteria stimulate the release of NE and PR3, which activities escape the control through degradation of locally produced inhibitors (SLPI and elafin) by host-derived and bacteria-derived proteases.