Sensitivity of <i>Actinobacillus actinomycetemcomitans</i> and <i>Capnocytophaga</i> spp. to the bactericidal action of LL‐37: a cathelicidin found in human leukocytes and epithelium

Tanaka, Duke; Miyasaki, Kenneth T.; Lehrer, Robert I.

doi:10.1034/j.1399-302x.2000.150403.x

Cited by 77 publications

(59 citation statements)

References 21 publications

(26 reference statements)

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“…GAS did not grow well under keratinocyte culture conditions, so S. aureus, an equally prominent human skin pathogen, was chosen for keratinocyte antimicrobial activity studies (35,56). Initially, assays were performed to verify cathelicidin antimicrobial activity against S. aureus in keratinocyte culture medium, since elevated concentrations of NaCl and serum have been reported to diminish the antimicrobial activity of several AMPs when assayed in vitro (4,5,21,53). Therefore, the antimicrobial activity of synthetic LL-37 peptide against S. aureus strains grown in either bacterial growth medium (TSB) or keratinocyte cell culture medium (EpiLife) was assessed.…”

Section: Discussionmentioning

confidence: 99%

Keratinocyte Production of Cathelicidin Provides Direct Activity against Bacterial Skin Pathogens

Braff¹,

et al. 2005

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Immune defense at an interface with the external environment reflects the functions of physical and chemical barriers provided by epithelial and immune cells. Resident epithelial cells, such as keratinocytes, produce numerous peptides with direct antimicrobial activity but also provide a physical barrier against invading pathogens and signal the recruitment of circulating immune cells, such as neutrophils. Antimicrobial peptides such as cathelicidin are produced constitutively by neutrophils and are inducible in keratinocytes in response to infection. The multiplicity of antimicrobial peptides and their cellular sources has resulted in an incomplete understanding of the role of cathelicidin production by epithelial cells in cutaneous immune defense. Therefore, this study sought to evaluate keratinocyte antimicrobial activity and the potential contribution of keratinocyte cathelicidin to host protection against two leading human skin pathogens. Wild-type mice and those with a targeted deletion of the cathelicidin gene, Cnlp, were rendered neutropenic prior to cutaneous infection. Interestingly, Cnlp-deficient mice remained more susceptible to group A streptococcus infection than mice with Cnlp intact, suggesting the involvement of epithelial cell-derived cathelicidin in host immune defense. Keratinocytes were then isolated in culture and found to inhibit the growth of Staphylococcus aureus, an effect that was partially dependent on their ability to synthesize and activate cathelicidin. Further, lentivirusmediated delivery of activated human cathelicidin enhanced keratinocyte antimicrobial activity. Combined, these data illustrate the potential contribution of keratinocyte cathelicidin to the innate immune defense of skin against bacterial pathogens and highlight the need to consider epithelial antimicrobial function in the diagnosis and therapy of skin infection.

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Section: Discussionmentioning

confidence: 99%

Keratinocyte Production of Cathelicidin Provides Direct Activity against Bacterial Skin Pathogens

Braff¹,

et al. 2005

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“…Interestingly, whilst KSL was less effective in inhibiting the growth of Actinobacillus actinomycetemcomitans and S. gordonii, as shown by the broth microdilution assay for MIC determinations, the peptide showed more potent inhibitory activity against the growth of these organisms in the bactericidal assay. These discrepancies could be attributable to the salinity of assay media used for determining the MICs and ED 99 of KSL, as indicated by a number of earlier reports on in vitro bactericidal activity of antimicrobial peptides (Lee et al, 1997;Friedrich et al, 1999;Tanaka et al, 2000; Guthmiller et al, 2001;Murakami et al, 2002;Zasloff, 2002).In this study, we were also interested in establishing the conformation of KSL in membrane environments. The three-dimensional structure of this antimicrobial peptide has not been reported previously, although the secondary structure of this peptide was predicted by circular dichroism (CD).…”

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confidence: 99%

Susceptibility of oral bacteria to an antimicrobial decapeptide

Concannon

Crowe

Abercrombie

et al. 2003

Journal of Medical Microbiology

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Naturally occurring antimicrobial peptides have emerged as alternative classes of antimicrobials. In general, these antimicrobial peptides exhibit selectivity for prokaryotes and minimize the problems of engendering microbial resistance. As an alternative method to search for more effective broadspectrum peptide antimicrobials, investigators have developed peptide libraries by using synthetic combinatorial technology. A novel decapeptide, KKVVFKVKFK (KSL), has been identified that shows a broad range of antibacterial activity. The purpose of this study was to test the efficacy of this antimicrobial peptide in killing selected strains of oral pathogens and resident saliva bacteria collected from human subjects. Cytotoxic activity of KSL against mammalian cells and the structural features of this decapeptide were also investigated, the latter by using two-dimensional NMR in aqueous and DMSO solutions. MICs of KSL for the majority of oral bacteria tested in vitro ranged from 3 to 100 ìg ml À1 . Minimal bactericidal concentrations of KSL were, in general, within one to two dilutions of the MICs. KSL exhibited an ED 99 (the dose at which 99 % killing was observed after 15 min at 37 8C) of 6 . 25 ìg ml À1 against selected strains of Lactobacillus salivarius, Streptococcus mutans, Streptococcus gordonii and Actinobacillus actinomycetemcomitans. In addition, KSL damaged bacterial cell membranes and caused 1 . 05 log units reduction of viability counts of saliva bacteria. In vitro toxicity studies showed that KSL, at concentrations up to 1 mg ml À1 , did not induce cell death or compromise the membrane integrity of human gingival fibroblasts. NMR studies suggest that KSL adopts an AE-helical structure in DMSO solution, which mimics the polar aprotic membrane environment, whereas it remains unstructured in aqueous medium. This study shows that KSL may be a useful antimicrobial agent for inhibiting the growth of oral bacteria that are associated with caries development and early plaque formation. INTRODUCTIONWe have witnessed the declining efficacy of conventional antibiotics in recent years, due to the progressive increase and proliferation of antibiotic-resistant organisms (Davies, 1994;Schutze et al., 1994). The discovery of a large number of naturally occurring invertebrate and vertebrate antimicrobial peptides has resulted in the emergence of alternative classes of peptide antibiotics that exhibit selectivity for prokaryotes and minimize the problems of introducing microbial resistance (Boman, 1998;Hancock & Lehrer, 1998;Hancock & Chapple, 1999;Nizet et al., 2001;Zasloff, 2002). These peptide antibiotics interact directly with microbial surfaces, often leading to the formation of pores or in some way compromising membrane permeability (Zasloff, 1992;Hancock, 1997a;Hancock & Rozek, 2002;Koczulla & Bals, 2003;Yeaman & Yount, 2003). Aside from their antimicrobial activities, some of these peptides also possess other biological activities that have impacts on cell proliferation, immune induction, cytokine release, chemota...

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“…The defensins and cathelicidins have broad antimicrobial activity against gram-negative and gram-positive bacteria and Candida albicans and are effective in vitro against oral microorganisms such as Streptococcus mutans, Porphyromonas gingi-valis, and Actinobacillus actinomycetemcomitans (5,13,25,35). The cathelicidins and ␣-and ␤-defensins act synergistically with other antimicrobials (19,24).…”

mentioning

confidence: 99%

Salivary Antimicrobial Peptide Expression and Dental Caries Experience in Children

Tao¹,

Jurevic²,

Coulton³

et al. 2005

Antimicrob Agents Chemother

182

170

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Dental caries is a major worldwide oral disease problem in children. Although caries are known to be influenced by dietary factors, the disease results from a bacterial infection; thus, caries susceptibility may be affected by host factors such as salivary antimicrobial peptides. This study aimed to determine a possible correlation between caries prevalence in children and salivary concentrations of the antimicrobial peptides human beta-defensin-3 (hBD-3), the cathelicidin LL37, and the alpha-defensins HNP1-3 (a mixture of HNP1, 2, 3). Oral examinations were performed on 149 middle school children, and unstimulated whole saliva was collected for immunoassays of the three peptides and for assay of caries-causing bacteria in saliva. The median salivary levels of hBD-3, LL37, and HNP1-3 were in the microgram/ml range but were highly variable in the population. While levels of LL37 and hBD-3 did not correlate with caries experience, the median HNP1-3 levels were significantly higher in children with no caries than in children with caries. Children with high caries levels did not have high levels of salivary Streptococcus mutans, and the HNP1-3 level was not correlated with salivary S. mutans. By immunohistochemistry we localized HNP1-3 in submandibular salivary duct cells. HNPs are also released by neutrophils into the gingival crevicular fluid. Both sources may account for their presence in saliva. Low salivary levels of HNP1-3 may represent a biological factor that contributes to caries susceptibility. This observation could lead to new ways to screen for caries susceptibility and to new means of assessing the risk for this common oral problem.

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Sensitivity of Actinobacillus actinomycetemcomitans and Capnocytophaga spp. to the bactericidal action of LL‐37: a cathelicidin found in human leukocytes and epithelium

Cited by 77 publications

References 21 publications

Keratinocyte Production of Cathelicidin Provides Direct Activity against Bacterial Skin Pathogens

Keratinocyte Production of Cathelicidin Provides Direct Activity against Bacterial Skin Pathogens

Susceptibility of oral bacteria to an antimicrobial decapeptide

Salivary Antimicrobial Peptide Expression and Dental Caries Experience in Children

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