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Journal of Periodontology Dec 2020Aggressive periodontitis is characterized by the early-onset and rapid progression of periodontal destruction and is closely associated with Aggregatibacter...
BACKGROUND
Aggressive periodontitis is characterized by the early-onset and rapid progression of periodontal destruction and is closely associated with Aggregatibacter actinomycetemcomitans. Autophagy is a conserved process that is critical for removing damaged proteins, organelles, and even intracellular pathogens. Therefore, this study examined whether A. actinomycetemcomitans induces autophagy. In addition, the relationship among autophagy, bacterial internalization, and inflammatory molecules in periodontal aggressive inflammation was analyzed.
METHODS
The expression of autophagy-related proteins in human gingival tissue and THP-1 cells was assessed by Western blot analysis. The formation of light chain 3 (LC3) puncta was examined by confocal microscopy. The degree of bacterial internalization into the cells was determined by the viable cell count. Phagocytosis and reactive oxygen species (ROS) production were measured using confocal microscopy and flow cytometry.
RESULTS
When macrophages were infected with live A. actinomycetemcomitans, the autophagy influx was activated by the increase in LC3-II, autophagy-related gene 5/12, and Beclin-1 expression through the Toll-like receptors and extracellular signal-regulated kinase signaling pathways. The inhibition of A. actinomycetemcomitans-induced autophagy suppressed bacterial internalization via phagocytosis into the macrophages and increased interleukin (IL)-1β production. Moreover, treatment with an ROS inhibitor inhibited these enhanced inflammatory responses.
CONCLUSIONS
A. actinomycetemcomitans-induced autophagy promotes bacterial internalization by phagocytosis, which restricts the excessive inflammatory response by downregulating IL-1β and ROS production in macrophages. Thus, A. actinomycetemcomitans-induced autophagy and its role in regulating the inflammatory response may play an important role in the aggressive periodontal inflammatory process, and be a target for the development of new periodontal therapies.
Topics: Aggregatibacter actinomycetemcomitans; Autophagy; Humans; Inflammation; Macrophages; Phagocytosis
PubMed: 32170963
DOI: 10.1002/JPER.19-0639 -
International Journal of Systematic and... Oct 2023Forty-one isolates of Bisgaard taxon 6 obtained from guinea pigs, pandas, pigs and muskrat and isolates of taxon 10 from horses and horse bites in humans were subjected...
Forty-one isolates of Bisgaard taxon 6 obtained from guinea pigs, pandas, pigs and muskrat and isolates of taxon 10 from horses and horse bites in humans were subjected phenotypic characterization. Production of acid from (-)-d-mannitol, (-)-d-sorbitol and (+)-d-glycogen separated taxon 10 (positive) from taxon 6 (negative), while from two to 11 phenotypic characteristics separated taxa 6 and 10 from the 32 genera of reported so far. Forty-four strains were genetically characterized. Sequencing of 16S rRNA genes documented a monophyletic relationship at the species level and the highest 16S rRNA gene sequence similarity of 95.6 % to other species was found between strain CCUG 15568 and the type strain of (CCUG 38457). Digital DNA-DNA hybridization (dDDH) values predicted from whole genomic sequences between CCUG 15568 and other characterized strains of taxa 6 and 10 were 69.3-99.9 %. The average nucleotide identity values were higher than 95 % for all strains. The highest dDDH value of 29 % outside the taxa 6 and 10 group was obtained with the genome of the type strain of [] , indicating a separate taxonomic status at species level to taxa 6 and 10. The phylogenetic comparison of concatenated conserved protein sequences showed the unique position of the taxa investigated in the current study which qualified for the status of a new genus since the highest identity was found with with 79 %, well below the upper threshold between genera of 85 %. Based upon the low genetic similarity to other genera of the family and a unique phenotype, we suggest that Bisgaard taxa 6 and 10 should be classified as gen. nov., sp. nov. The G+C of the type strain of , 8.5 (=CCUG 15568=DSM 115565), is 46.2 mol%, calculated from the whole genome.
Topics: Humans; Animals; Guinea Pigs; Horses; Phylogeny; RNA, Ribosomal, 16S; Sequence Analysis, DNA; DNA, Bacterial; Bacterial Typing Techniques; Base Composition; Fatty Acids; Pasteurellaceae
PubMed: 37882672
DOI: 10.1099/ijsem.0.006092 -
Enfermedades Infecciosas Y... Feb 2021
Topics: Haemophilus Infections; Haemophilus influenzae; Humans
PubMed: 33279275
DOI: 10.1016/j.eimc.2020.10.007 -
Journal of Veterinary Diagnostic... Nov 2021Neurologic diseases are common in domestic cats, and infectious agents are suspected to be the primary cause in 30-45% of cases. Among infectious etiologies, those of... (Review)
Review
Neurologic diseases are common in domestic cats, and infectious agents are suspected to be the primary cause in 30-45% of cases. Among infectious etiologies, those of bacterial origin are only sporadically characterized in the literature, with few of these reports correlating gross and histologic findings with confirmatory bacteriologic identification. Here, we describe bacterial meningitis and meningoencephalomyelitis associated with in 3 domestic cats. Purulent exudate expanding the cerebral meninges was grossly evident in 2 of the cases. In all 3 cases, histologic changes included multifocal suppurative-to-necrosuppurative meningitis and/or meningoencephalomyelitis of variable severity. Intralesional colonies of gram-negative, short rod-shaped to coccobacillary bacteria were evident histologically in only 1 case. was confirmed by routine bacteriologic culture in all cases. Based on our cases, we hypothesize that the upper respiratory system serves as the main portal of entry for , leading to invasion of the central nervous system and possible systemic hematogenous dissemination. A case series of meningoencephalomyelitis associated with infection in cats has not been reported previously, to our knowledge. We also review briefly other causes of meningoencephalomyelitis in cats.
Topics: Animals; Cat Diseases; Cats; Meningitis, Bacterial; Pasteurella Infections; Pasteurella multocida
PubMed: 34301172
DOI: 10.1177/10406387211034484 -
QJM : Monthly Journal of the... Sep 2020
Topics: Aneurysm, Infected; Humans; Pasteurella multocida
PubMed: 32016425
DOI: 10.1093/qjmed/hcaa020 -
The Journal of Antimicrobial... Jun 2021To characterize the mechanisms of antimicrobial resistance and the prevalence of the polysaccharide capsule among urogenital and respiratory Haemophilus parainfluenzae...
OBJECTIVES
To characterize the mechanisms of antimicrobial resistance and the prevalence of the polysaccharide capsule among urogenital and respiratory Haemophilus parainfluenzae isolates.
METHODS
Antimicrobial susceptibility was tested by microdilution. Fifty-five MDR strains were subjected to WGS and were phylogenetically compared with all the available H. parainfluenzae genomes from the NCBI database. The identification of the capsular bexA gene was performed by PCR in 266 non-MDR strains.
RESULTS
In 31 of the 42 ampicillin-resistant strains, blaTEM-1 located within Tn3 was identified. β-Lactamase-negative cefuroxime-resistant strains (n = 12) presented PBP3 substitutions. The catS gene (n = 14), the tet(M)-MEGA element (n = 18) and FolA substitutions (I95L and F154V/S) (n = 41) were associated with resistance to chloramphenicol, tetracycline plus macrolides, and co-trimoxazole, respectively. Thirty-seven isolates had a Tn10 harbouring tet(B)/(C)/(D)/(R) genes with (n = 15) or without (n = 22) catA2. Putative transposons (Tn7076-Tn7079), including aminoglycoside and co-trimoxazole resistance genes, were identified in 10 strains (18.2%). These transposons were integrated into three new integrative and conjugative elements (ICEs), which also included the resistance-associated transposons Tn3 and Tn10. The capsular operon was found only in the urogenital isolates (18/154, 11.7%), but no phylogenetic clustering was observed. The capsular operons identified were similar to those of Haemophilus influenzae serotype c and Haemophilus sputorum type 2.
CONCLUSIONS
The identification of ICEs with up to three resistance-associated transposons suggests that these transferable elements play an important role in the acquisition of multidrug resistance in H. parainfluenzae. Moreover, the presence of polysaccharide capsules in some of these urogenital isolates is a cause for concern.
Topics: Ampicillin; Anti-Bacterial Agents; Haemophilus; Haemophilus Infections; Haemophilus influenzae; Haemophilus parainfluenzae; Humans; Microbial Sensitivity Tests
PubMed: 33792695
DOI: 10.1093/jac/dkab109 -
Computer Methods and Programs in... Jul 2022The leukotoxin (LtxA) of Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) is a protein exotoxin belonging to the repeat-in-toxin family (RTX). Numerous...
The leukotoxin (LtxA) of Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) is a protein exotoxin belonging to the repeat-in-toxin family (RTX). Numerous studies have demonstrated that LtxA may play a critical role in the pathogenicity of A. actinomycetemcomitans since hyper-leukotoxic strains have been associated with severe disease. Accordingly, considerable effort has been made to elucidate the mechanisms by which LtxA interacts with host cells and induce their death. However, these attempts have been hampered by the unavailability of a tertiary structure of the toxin, which limits the understanding of its molecular properties and mechanisms. In this paper, we used homology and template free modeling algorithms to build the complete tertiary model of LtxA at atomic level in its calcium-bound Holo-state. The resulting model was refined by energy minimization, validated by Molprobity and ProSA tools, and subsequently subjected to a cumulative 600ns of all-atom classical molecular dynamics simulation to evaluate its structural aspects. The druggability of the proposed model was assessed using Fpocket and FTMap tools, resulting in the identification of four putative cavities and fifteen binding hotspots that could be targeted by rational drug design tools to find new ligands to inhibit LtxA activity.
Topics: Aggregatibacter actinomycetemcomitans; Computer Simulation; Exotoxins
PubMed: 35724475
DOI: 10.1016/j.cmpb.2022.106952 -
Molecular Ecology Sep 2021Most species in the bacterial family of Pasteurellaceae colonize one specific host species. Vertebrates of very different evolutionary descent including fish, turtles,...
Most species in the bacterial family of Pasteurellaceae colonize one specific host species. Vertebrates of very different evolutionary descent including fish, turtles, marsupials, eutherians and birds are colonized by different members of Pasteurellaceae. This one-to-one microbial-host species partnership makes Pasteurellaceae species valuable candidates to study biodiversity, bacterial-host co-evolution and host adaptation, and their widespread distribution across vertebrates provide the possibility to collect a wide array of data, where wildlife species are essential. However, obtaining samples from wild animals comes with logistic, technical and ethical challenges, and previous microbiota studies have led to the presumption that captive animals are poor models for microbial studies in wildlife. Here, we show that colonization of polar bears by Ursidibacter maritimus is unaffected by factors related to captivity, reflecting a deep symbiotic bond to the host. We argue that the study of ecological and evolutionary principles in captive wildlife is possible for host-adapted taxa such as those in the Pasteurellaceae family. Moreover, studying captive, often trained animals protects wild populations from the stress associated with obtaining samples.
Topics: Animals; Animals, Wild; Birds; Pasteurellaceae; Ursidae
PubMed: 34250662
DOI: 10.1111/mec.16075 -
Biochemical and Biophysical Research... Dec 2022The cytolethal distending toxins (CDTs) produced by many Gram-negative pathogens are tripartite genotoxins with a single catalytic subunit (CdtB) and two cell-binding...
The cytolethal distending toxins (CDTs) produced by many Gram-negative pathogens are tripartite genotoxins with a single catalytic subunit (CdtB) and two cell-binding subunits (CdtA + CdtC). CDT moves by vesicle carriers from the cell surface to the endosomes and through the Golgi apparatus en route to the endoplasmic reticulum (ER). CdtA dissociates from the rest of the toxin before reaching the Golgi apparatus, and CdtB separates from CdtC in the ER. The free CdtB subunit, which is only active after holotoxin disassembly, then crosses the ER membrane and enters the nucleus where it generates DNA breaks. We hypothesized that the acidified lumen of the endosomes is responsible for separating CdtA from the CdtB/CdtC heterodimer. To test this prediction, possible acid-induced disruptions to the CDT holotoxin were monitored by size exclusion chromatography and surface plasmon resonance. We found that CDT could not efficiently assemble from its individual subunits at the early endosome pH of 6.3. Partial disassembly of the CDT holotoxin also occurred at pH 6.3, with complete separation of CdtA from an intact CdtB/CdtC heterodimer occurring at both pH 6.0 and the late endosome pH of 5.6. Acidification caused the precipitation of CdtA at pH 6.5 and below, but neither CdtB nor CdtC were affected by a pH as low as 5.2. Circular dichroism further showed that the individual CdtB subunit adopts a different secondary structure as compared to its structure in the holotoxin. We conclude the first stage of CDT disassembly occurs in the early endosomes, where an acid-induced alteration to CdtA releases it from the CdtB/CdtC heterodimer.
Topics: Haemophilus ducreyi; Bacterial Toxins
PubMed: 36332483
DOI: 10.1016/j.bbrc.2022.10.068 -
Proceedings of the National Academy of... Oct 2019is associated with aggressive periodontitis resulting in premature tooth loss in adolescents. Tooth adherence and biofilm persistence are prerequisites for survival in...
is associated with aggressive periodontitis resulting in premature tooth loss in adolescents. Tooth adherence and biofilm persistence are prerequisites for survival in the oral domain. Here, using a rhesus monkey model, 16S rRNA sequencing, and weighted network analysis, we assessed colonization of variants and ascertained microbial interactions in biofilm communities. Variants in leukotoxin () were created, labeled, inoculated, and compared with their progenitor strain for in vivo colonization. Samples of tooth-related plaque were assessed for colonization at baseline and after debridement and inoculation of labeled strains. Null, minimal, and hyper-Ltx-producing strains were created and assessed for hydroxyapatite binding and biofilm formation in vitro. Ltx-hyperproducing strains colonized with greater prevalence and at higher levels than wild type or mutants ( = 0.05). Indigenous and inoculated strains that attached were associated with lactate-producing species (i.e., Leptotrichia, Abiotrophia, and Streptoccocci). was found at 0.13% of the total flora at baseline and at 0.05% 4 wk after inoculation. In vivo data were supported by in vitro results. We conclude that hyper-Ltx production affords these strains with an attachment advantage providing a foothold for competition with members of the indigenous microbiota. Increased attachment can be linked to gene expression and up-regulation of adherence-associated genes. Growth of attached in vivo was enhanced by lactate availability due to consorting species. These associations provide with the constituents required for its colonization and survival in the complex and competitive oral environment.
Topics: Aggregatibacter actinomycetemcomitans; Animals; Bacterial Adhesion; Biofilms; Durapatite; Exotoxins; Lactic Acid; Macaca mulatta; Male; Microbiota; Mouth; Periodontitis
PubMed: 31611409
DOI: 10.1073/pnas.1905238116