scholarly journals The Antibacterial Activity of LL-37 against Treponema denticola Is Dentilisin Protease Independent and Facilitated by the Major Outer Sheath Protein Virulence Factor

2011 ◽  
Vol 80 (3) ◽  
pp. 1107-1114 ◽  
Author(s):  
Graciela Rosen ◽  
Michael N. Sela ◽  
Gilad Bachrach
Keyword(s):  
Periodontal Disease ◽  
Host Defense ◽  
Surface Protein ◽  
Human Saliva ◽  
Treponema Denticola ◽  
Host Defense Peptides ◽  
Content Type ◽  
Outer Sheath ◽  
Major Surface

Host defense peptides are innate immune effectors that possess both bactericidal activities and immunomodulatory functions. Deficiency in the human host defense peptide LL-37 has previously been correlated with severe periodontal disease.Treponema denticolais an oral anaerobic spirochete closely associated with the pathogenesis of periodontal disease. TheT. denticolamajor surface protein (MSP), involved in adhesion and cytotoxicity, and the dentilisin serine protease are key virulence factors of this organism. In this study, we examined the interactions between LL-37 andT. denticola. The threeT. denticolastrains tested were susceptible to LL-37. Dentilisin was found to inactivate LL-37 by cleaving it at the Lys, Phe, Gln, and Val residues. However, dentilisin deletion did not increase the susceptibility ofT. denticolato LL-37. Furthermore, dentilisin activity was found to be inhibited by human saliva. In contrast, a deficiency of theT. denticolaMSP increased resistance to LL-37. The MSP-deficient mutant bound less fluorescently labeled LL-37 than the wild-type strain. MSP demonstrated specific, dose-dependent LL-37 binding. In conclusion, though capable of LL-37 inactivation, dentilisin does not protectT. denticolafrom LL-37. Rather, the rapid, MSP-mediated binding of LL-37 to the treponemal outer sheath precedes cleavage by dentilisin. Moreover,in vivo, saliva inhibits dentilisin, thus preventing LL-37 restriction and ensuring its bactericidal and immunoregulatory activities.

scholarly journals In Vitro and In Vivo Antibiotic Capacity of Two Host Defense Peptides

2020 ◽  
Vol 64 (7) ◽  
Author(s):  
Iván Arenas ◽  
Marco Antonio Ibarra ◽  
Felix L. Santana ◽  
Elba Villegas ◽  
Robert E. W. Hancock ◽  
...  
Keyword(s):  
Host Defense ◽  
Foot Ulcer ◽  
Diabetic Foot Ulcer ◽  
Immunomodulatory Activity ◽  
Host Defense Peptides ◽  
Content Type ◽  
Serovar Typhimurium ◽  
Infective Activity

ABSTRACT Two nonamidated host defense peptides named Pin2[G] and FA1 were evaluated against three types of pathogenic bacteria: two (Staphylococcus aureus UPD13 and Pseudomonas aeruginosa UPD3) isolated from diabetic foot ulcer patients, and another (Salmonella enterica serovar Typhimurium [ATCC 14028]) from a commercial collection. In vitro experiments showed that the antimicrobial performance of the synthetic peptides Pin2[G] and FA1 was modest, although FA1 was more effective than Pin2[G]. In contrast, Pin2[G] had superior in vivo anti-infective activity to FA1 in rabbit wound infections by the diabetic foot ulcer pathogens S. aureus UPD13 and P. aeruginosa UPD3. Indeed, Pin2[G] reduced bacterial colony counts of both S. aureus UPD13 and P. aeruginosa UPD3 by >100,000-fold after 48 to 72 h on skin wounds of infected rabbits, while in similar infected wounds, FA1 had no major effects at 72 to 96 h of treatment. Ceftriaxone was equally effective versus Pseudomonas but less effective versus S. aureus infections. Additionally, the two peptides were evaluated in mice against intragastrically inoculated S. enterica serovar Typhimurium (ATCC 14028). Only Pin2[G] at 0.56 mg/kg was effective in reducing systemic (liver) infection by >67-fold, equivalent to the effect of treatment with levofloxacin. Pin2[G] showed superior immunomodulatory activity in increasing chemokine production by a human bronchial cell line and suppressing polyinosinic-polycytidylic acid (poly[I:C])-induced proinflammatory IL-6 production. These data showed that the in vitro antimicrobial activity of these peptides was not correlated with their in vivo anti-infective activity and suggest that other factors such as immunomodulatory activity were more important.

scholarly journals Potential of Host Defense Peptide Prodrugs as Neutrophil Elastase-Dependent Anti-Infective Agents for Cystic Fibrosis

2013 ◽  
Vol 58 (2) ◽  
pp. 978-985 ◽  
Author(s):  
Éanna Forde ◽  
Hilary Humphreys ◽  
Catherine M. Greene ◽  
Deirdre Fitzgerald-Hughes ◽  
Marc Devocelle
Keyword(s):  
Cystic Fibrosis ◽  
Host Defense ◽  
Bactericidal Activity ◽  
Neutrophil Elastase ◽  
Activity Levels ◽  
Host Defense Peptides ◽  
Content Type ◽  
Host Defense Peptide ◽  
Low Toxicity

ABSTRACTHost defense peptides (HDPs) are short antimicrobial peptides of the innate immune system. Deficiencies in HDPs contribute to enhanced susceptibility to infections, e.g., in cystic fibrosis (CF). Exogenous HDPs can compensate for these deficiencies, but their development as antimicrobials is limited by cytotoxicity. Three HDP prodrugs were designed so their net positive charge is masked by a promoiety containing a substrate for the enzyme neutrophil elastase (NE). This approach can confine activation to sites with high NE levels. Enzyme-labile peptides were synthesized, and their activation was investigated using purified NE. Susceptibilities ofPseudomonas aeruginosato parent and prodrug peptides in the presence and absence of NE-rich CF human bronchoalveolar lavage (BAL) fluid and different NaCl concentrations were compared. The effect of the HDP promoiety on cytotoxicity was determined with cystic fibrosis bronchial epithelial (CFBE41o-) cells. NE in CF BAL fluids activated the HDP prodrugs, restoring bactericidal activity against reference and clinical isolates ofP. aeruginosa. However, activation also required the addition of 300 mM NaCl. Under these conditions, the bactericidal activity levels of the HDP prodrugs differed, with pro-P18 demonstrating the greatest activity (90% to 100% of that of the parent, P18, at 6.25 μg/ml). Cytotoxic effects on CFBE41o- cells were reduced by the addition of the promoiety to HDPs. We demonstrate here for the first time the selective activation of novel HDP prodrugs by a host disease-associated enzyme atin vivoconcentrations of the CF lung. This approach may lead to the development of novel therapeutic agents with low toxicity that are active under the challenging conditions of the CF lung.

scholarly journals Mechanistic Fingerprinting Reveals Kinetic Signatures of Resistance to Daptomycin and Host Defense Peptides in Streptococcus mitis-oralis

Antibiotics ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 404
Author(s):  
Michael R. Yeaman ◽  
Liana C. Chan ◽  
Nagendra N. Mishra ◽  
Arnold S. Bayer
Keyword(s):  
Flow Cytometry ◽  
Host Defense ◽  
Durable Resistance ◽  
Cross Resistance ◽  
Streptococcus Mitis ◽  
Host Defense Peptides ◽  
Strain Pair ◽  
Defense Peptides

Streptococcus mitis-oralis (S. mitis-oralis) infections are increasingly prevalent in specific populations, including neutropenic cancer and endocarditis patients. S. mitis-oralis strains have a propensity to evolve rapid, high-level and durable resistance to daptomycin (DAP-R) in vitro and in vivo, although the mechanism(s) involved remain incompletely defined. We examined mechanisms of DAP-R versus cross-resistance to cationic host defense peptides (HDPs), using an isogenic S. mitis-oralis strain-pair: (i) DAP-susceptible (DAP-S) parental 351-WT (DAP MIC = 0.5 µg/mL), and its (ii) DAP-R variant 351-D10 (DAP MIC > 256 µg/mL). DAP binding was quantified by flow cytometry, in-parallel with temporal (1–4 h) killing by either DAP or comparative prototypic cationic HDPs (hNP-1; LL-37). Multicolor flow cytometry was used to determine kinetic cell responses associated with resistance or susceptibility to these molecules. While overall DAP binding was similar between strains, a significant subpopulation of 351-D10 cells hyper-accumulated DAP (>2–4-fold vs. 351-WT). Further, both DAP and hNP-1 induced cell membrane (CM) hyper-polarization in 351-WT, corresponding to significantly greater temporal DAP-killing (vs. 351-D10). No strain-specific differences in CM permeabilization, lipid turnover or regulated cell death were observed post-exposure to DAP, hNP-1 or LL-37. Thus, the adaptive energetics of the CM appear coupled to the outcomes of interactions of S. mitis-oralis with DAP and selected HDPs. In contrast, altered CM permeabilization, proposed as a major mechanism of action of both DAP and HDPs, did not differentiate DAP-S vs. DAP-R phenotypes in this S. mitis-oralis strain-pair.

scholarly journals Invasion of Oral and Aortic Tissues by Oral Spirochete Treponema denticola in ApoE−/−Mice Causally Links Periodontal Disease and Atherosclerosis

2014 ◽  
Vol 82 (5) ◽  
pp. 1959-1967 ◽  
Author(s):  
Sasanka S. Chukkapalli ◽  
Mercedes F. Rivera ◽  
Irina M. Velsko ◽  
Ju-Youn Lee ◽  
Hao Chen ◽  
...  
Keyword(s):  
Periodontal Disease ◽  
Alveolar Bone ◽  
Tissue Growth ◽  
Aortic Tissue ◽  
Treponema Denticola ◽  
Rapid Progression ◽  
Causative Role ◽  
Igg Antibody ◽  
Content Type ◽  
Periodontal Infection

ABSTRACTTreponema denticolais a predominantly subgingival oral spirochete closely associated with periodontal disease and has been detected in atherosclerosis. This study was designed to evaluate causative links between periodontal disease induced by chronic oralT. denticolainfection and atherosclerosis in hyperlipidemic ApoE−/−mice. ApoE−/−mice (n= 24) were orally infected withT. denticolaATCC 35404 and were euthanized after 12 and 24 weeks.T. denticolagenomic DNA was detected in oral plaque samples, indicating colonization of the oral cavity. Infection elicited significantly (P= 0.0172) higher IgG antibody levels and enhanced intrabony defects than sham infection.T. denticola-infected mice had higher levels of horizontal alveolar bone resorption than sham-infected mice and an associated significant increase in aortic plaque area (P≤ 0.05). Increased atherosclerotic plaque correlated with reduced serum nitric oxide (NO) levels and increased serum-oxidized low-density lipoprotein (LDL) levels compared to those of sham-infected mice.T. denticolainfection altered the expression of genes known to be involved in atherosclerotic development, including the leukocyte/endothelial cell adhesion gene (Thbs4), the connective tissue growth factor gene (Ctgf), and the selectin-E gene (Sele). Fluorescentin situhybridization (FISH) revealedT. denticolaclusters in both gingival and aortic tissue of infected mice. This is the first study examining the potential causative role of chronicT. denticolaperiodontal infection and vascular atherosclerosisin vivoin hyperlipidemic ApoE−/−mice.T. denticolais closely associated with periodontal disease and the rapid progression of atheroma in ApoE−/−mice. These studies confirm a causal link for active oralT. denticolainfection with both atheroma and periodontal disease.

scholarly journals TheTreponema denticolaPAS Domain-Containing Histidine Kinase Hpk2 Is a Heme Binding Sensor of Oxygen Levels

2018 ◽  
Vol 200 (18) ◽  
Author(s):  
Juni Sarkar ◽  
Daniel P. Miller ◽  
Lee D. Oliver ◽  
Richard T. Marconi
Keyword(s):  
Microbial Community ◽  
Periodontal Disease ◽  
Histidine Kinase ◽  
Site Directed Mutagenesis ◽  
Directed Mutagenesis ◽  
Treponema Denticola ◽  
Pas Domain ◽  
Adaptive Responses ◽  
Content Type

ABSTRACTPeriodontal disease (PD) results from a shift in the composition of the microbial community of the subgingival crevice. As the bacterial population transitions from Gram-positive bacteria to predominantly Gram-negative anaerobes and spirochetes, dramatic changes occur in the physiological and immunological environment at diseased sites.Treponema denticolathrives in periodontal pockets, indicating that it has a unique ability to adapt to changing environmental conditions. Hpk2 (tde1970), a Per-Arnt-Sim motif (PAS) domain-containing histidine kinase (HK), is part of theT. denticolaHpk2-Rrp2 (tde1969) two-component regulatory (TCR) system. This TCR system is growth phase regulated and has been postulated to play a key role in adaptive responses. In this study, we employ predictive structural analyses and site-directed mutagenesis to investigate the functional role of specific amino acid residues located within the Hpk2 PAS domain. Specific substitutions impacted autophosphorylation (AP), phosphotransfer (PT), oligomerization, and hemin binding. The AP, PT, hemin binding, and oligomerization potential of some mutated Hpk2 proteins differed under aerobic versus anaerobic reaction conditions. The data presented here suggest that the regulatory activity of Hpk2 is linked to diatomic gas levels. In a broader sense, this study highlights the importance of studying proteins produced by anaerobes under conditions that approximate the environment in which they thrive.IMPORTANCEPeriodontal disease affects nearly 60% of the global adult population. Its costs to individuals, and to society as a whole, are enormous. As periodontal disease develops, there is a shift in the composition of the oral microbial community. The bacteria that become dominant are able to cause significant damage to the tissues that support the teeth, leading to tooth loss.Treponema denticolais one of the keystone pathogens associated with periodontal disease. An earlier study demonstrated that the Hpk2 and Rrp2 proteins play an important role in adaptive responses. Here, we explore the role of specific Hpk2 amino acids in environmental sensing and function, using structural analyses and site-directed mutagenesis.

scholarly journals B Cell Activating Factor Inhibition Impairs Bacterial Immunity by Reducing T Cell-Independent IgM Secretion

2013 ◽  
Vol 81 (12) ◽  
pp. 4490-4497 ◽  
Author(s):  
Derek D. Jones ◽  
Maura Jones ◽  
Gregory A. DeIulio ◽  
Rachael Racine ◽  
Katherine C. MacNamara ◽  
...  
Keyword(s):  
Cell Differentiation ◽  
T Cell ◽  
B Cell ◽  
Host Defense ◽  
B Cell Differentiation ◽  
Content Type ◽  
Surface Marker Expression ◽  
B Cell Activating Factor

ABSTRACTB cell activating factor of the tumor necrosis factor family (BAFF) is an essential survival factor for B cells and has been shown to regulate T cell-independent (TI) IgM production. DuringEhrlichia murisinfection, TI IgM secretion in the spleen was BAFF dependent, and antibody-mediated BAFF neutralization led to an impairment of IgM-mediated host defense. The failure of TI plasmablasts to secrete IgM was not a consequence of alterations in their generation, survival, or early differentiation, since all occurred normally in infected mice following BAFF neutralization. Gene expression characteristic of plasma cell differentiation was also unaffected by BAFF neutralizationin vivo, and except for CD138, plasmablast cell surface marker expression was unaffected. IgM was produced, since it was detected intracellularly, and impaired secretion was not due to a failure to express the IgM secretory exon. Addition of BAFF to plasmablastsin vitrorescued IgM secretion, suggesting that BAFF signaling can directly regulate secretory processes. Our findings indicate that BAFF signaling can modulate TI host defense by acting at a late stage in B cell differentiation, via its regulation of terminal plasmablast differentiation and/or IgM secretion.

scholarly journals Efficacy of Synthetic Peptides RP-1 and AA-RP-1 against Leishmania SpeciesIn VitroandIn Vivo

2011 ◽  
Vol 56 (2) ◽  
pp. 658-665 ◽  
Author(s):  
Marie Crisel B. Erfe ◽  
Consuelo V. David ◽  
Cher Huang ◽  
Victoria Lu ◽  
Ana Claudia Maretti-Mira ◽  
...  
Keyword(s):  
Intravenous Administration ◽  
Synthetic Peptides ◽  
Antileishmanial Activity ◽  
Host Defense Peptides ◽  
Content Type ◽  
Causative Agents ◽  
Antileishmanial Activities ◽  
Conventional Antibiotics

ABSTRACTHost defense peptides are naturally occurring molecules that play essential roles in innate immunity to infection. Based on prior structure-function knowledge, we tested two synthetic peptides (RP-1 and AA-RP-1) modeled on the conserved, microbicidal α-helical domain of mammalian CXCL4 platelet kinocidins. These peptides were evaluated for efficacy againstLeishmaniaspecies, the causative agents of the group of diseases known as leishmaniasis.In vitroantileishmanial activity was assessed against three distinctLeishmaniastrains by measuring proliferation, metabolic activity and parasite viability after exposure to various concentrations of peptides. We demonstrate that micromolar concentrations of RP-1 and AA-RP-1 caused dose-dependent growth inhibition ofLeishmaniapromastigotes. This antileishmanial activity correlated with rapid membrane disruption, as well as with a loss of mitochondrial transmembrane potential. In addition, RP-1 and AA-RP-1 demonstrated distinct and significantin vivoantileishmanial activities in a mouse model of experimental visceral leishmaniasis after intravenous administration. These results establish efficacy of RP-1 lineage synthetic peptides againstLeishmaniaspeciesin vitroand after intravenous administrationin vivoand provide further validation of proof of concept for the development of these and related systemic anti-infective peptides targeting pathogens that are resistant to conventional antibiotics.

scholarly journals Collagen VI Contains Multiple Host Defense Peptides with Potent In Vivo Activity

2018 ◽  
Vol 201 (3) ◽  
pp. 1007-1020 ◽  
Author(s):  
Suado M. Abdillahi ◽  
Tobias Maaß ◽  
Gopinath Kasetty ◽  
Adam A. Strömstedt ◽  
Maria Baumgarten ◽  
...  
Keyword(s):  
Host Defense ◽  
Collagen Vi ◽  
Host Defense Peptides ◽  
Defense Peptides

scholarly journals Host Defense Proteins Derived from Human Saliva Bind to Staphylococcus aureus

2013 ◽  
Vol 81 (4) ◽  
pp. 1364-1373 ◽  
Author(s):  
Seok-Mo Heo ◽  
Kyoung-Soo Choi ◽  
Latif A. Kazim ◽  
Molakala S. Reddy ◽  
Elaine M. Haase ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Oral Cavity ◽  
Host Defense ◽  
Bacterial Colonization ◽  
Human Saliva ◽  
Salivary Protein ◽  
Salivary Proteins ◽  
Staphylococcal Protein A ◽  
Defense Proteins ◽  
Content Type

ABSTRACTProteins in human saliva are thought to modulate bacterial colonization of the oral cavity. Yet, information is sparse on how salivary proteins interact with systemic pathogens that transiently or permanently colonize the oral environment.Staphylococcus aureusis a pathogen that frequently colonizes the oral cavity and can cause respiratory disease in hospitalized patients at risk. Here, we investigated salivary protein binding to this organism upon exposure to saliva as a first step toward understanding the mechanism by which the organism can colonize the oral cavity of vulnerable patients. By using fluorescently labeled saliva and proteomic techniques, we demonstrated selective binding of major salivary components byS. aureusto include DMBT1gp-340, mucin-7, secretory component, immunoglobulin A, immunoglobulin G, S100-A9, and lysozyme C. Biofilm-grownS. aureusstrains bound fewer salivary components than in the planctonic state, particularly less salivary immunoglobulins. A corresponding adhesive component on theS. aureussurface responsible for binding salivary immunoglobulins was identified as staphylococcal protein A (SpA). However, SpA did not mediate binding of nonimmunoglobulin components, including mucin-7, indicating the involvement of additional bacterial surface adhesive components. These findings demonstrate that a limited number of salivary proteins, many of which are associated with various aspects of host defense, selectively bind toS. aureusand lead us to propose a possible role of saliva in colonization of the human mouth by this pathogen.

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