| 1. |
- Collin, Mattias, et al.
(författare)
-
Bacterial Modulation of Fc Effector Functions
- 2013
-
Ingår i: Antibody Fc : Linking Adaptive and Innate Immunity - Linking Adaptive and Innate Immunity. - 9780123948021 ; , s. 317-332
-
Bokkapitel (refereegranskat)abstract
- Immunoglobulins (Igs, antibodies) are key players in adaptive immunity, and pathways mediated through the effector Fc portion of Ig are instrumental in controlling bacterial infections. Therefore, it is not very surprising that bacterial pathogens and commensals through co-evolution with their hosts have learned many tricks to interfere with Fc effector functions. In this chapter, we describe three principally different bacterial strategies to interfere with immunoglobulins: Specific Ig binding, specific or unspecific Ig protelolysis, and, finally, specific and unspecific hydrolysis of functionally important carbohydrates on the immunoglobulins. Elucidating these bacterial immune evasion mechanism evidences bacteria-host co-evolution and provides insight into fundamental aspects of human adaptive immunity and pathogenesis of infection.
|
|
| 2. |
- Dige, Irene, et al.
(författare)
-
In situ identification of streptococci and other bacteria in initial dental biofilm by confocal laser scanning microscopy and fluorescence in situ hybridization.
- 2007
-
Ingår i: European journal of oral sciences. - : Wiley. - 0909-8836 .- 1600-0722. ; 115:6, s. 459-67
-
Tidskriftsartikel (refereegranskat)abstract
- Confocal laser scanning microscopy (CLSM) has been employed as a method for studying intact natural biofilm. When combined with fluorescence in situ hybridization (FISH) it is possible to analyze spatial relationships and changes of specific members of microbial populations over time. The aim of this study was to perform a systematic description of the pattern of initial dental biofilm formation by applying 16S rRNA-targeted oligonucleotide probes to the identification of streptococci and other bacteria, and to evaluate the usefulness of the combination of CLSM and FISH for structural studies of bacterial populations in dental biofilm. Biofilms were collected on standardized glass slabs mounted in intra-oral appliances and worn by 10 individuals for 6, 12, 24 or 48 h. After intra-oral exposure the biofilms were labelled with probes against either streptococci (STR405) or all bacteria (EUB338) and analysed by CLSM. The current approach of using FISH techniques enabled differentiation of streptococci from other bacteria and determination of their spatio-temporal organization. The presence of chimney-like multilayered microcolonies with different microbial compositions demonstrated by this methodology provided information supplementary to our previous knowledge obtained by classical electron microscopic methods and increased our understanding of the structure of developing biofilms.
|
|
| 3. |
- Drobni, Mirva, et al.
(författare)
-
A host-derived pentapeptide enhancing host-bacteria commensalisms and communication
- 2006
-
Ingår i: Infection and Immunity. - Washington : American society for microbiology. - 0019-9567 .- 1098-5522. ; 74:11, s. 6293-6299
-
Tidskriftsartikel (refereegranskat)abstract
- Salivary proline-rich proteins (PRPs) attach commensal Actinomyces and Streptococcus species to teeth. Here, gel filtration, mass spectrometry and Edman degradation were applied to show the release of a pentapeptide, RGRPQ, from PRP-1 upon proteolysis by Streptococcus gordond. Moreover, synthetic RGRPQ and derivatives were used to investigate associated innate properties and responsible motifs. The RGRPQ peptide increased 2.5-fold the growth rate of S. gordonii via a Q-dependent sequence motif and selectively stimulated oral colonization of this organism in a rat model in vivo. In contrast, the growth of Streptococcus mutans, implicated in caries, was not affected. While the entire RGRPQ sequence was required to block sucrose-induced pH-decrease by S. gordonii and S. mutans, the N-terminal Arg residue mediated the pH increase (i.e., ammonia production) by S. gordonii alone (which exhibits Arg catabolism to ammonia). Strains of commensal viridans streptococci exhibited PR-P degradation and Arg catabolism, whereas cariogenic species did not. The RGRPQ peptide mediated via a differential Q-dependent sequence motif, adhesion inhibition, and desorption of PRP-1-binding strains of A. naeslundii genospecies 2 (5 of 10 strains) but not of S. gordonii (n = 5). The inhibitable A. naeslundii strains alone displayed the same binding profile as S. gordond to hybrid peptides terminating in RGRPQ or GQSPQ, derived from the middle or C-terminal segments of PRP-1. The present findings indicate the presence of a host-bacterium interaction in which a host peptide released by bacterial proteolysis affects key properties in biofilm formation.
|
|
| 4. |
- Drobni, Mirva, et al.
(författare)
-
Host-derived pentapeptide affecting adhesion, proliferation, and local pH in biofilm communities composed of Streptococcus and Actinomyces species.
- 2006
-
Ingår i: Infection and Immunity. - 0019-9567 .- 1098-5522. ; 74:11, s. 6293-6299
-
Tidskriftsartikel (refereegranskat)abstract
- Salivary proline-rich proteins (PRPs) attach commensal Actinomyces and Streptococcus species to teeth. Here, gel filtration, mass spectrometry and Edman degradation were applied to show the release of a pentapeptide, RGRPQ, from PRP-1 upon proteolysis by Streptococcus gordonii. Moreover, synthetic RGRPQ and derivatives were used to investigate associated innate properties and responsible motifs. The RGRPQ peptide increased 2.5-fold the growth rate of S. gordonii via a Q-dependent sequence motif and selectively stimulated oral colonization of this organism in a rat model in vivo. In contrast, the growth of Streptococcus mutans, implicated in caries, was not affected. While the entire RGRPQ sequence was required to block sucrose-induced pH-decrease by S. gordonii and S. mutans, the N-terminal Arg residue mediated the pH increase (i.e., ammonia production) by S. gordonii alone (which exhibits Arg catabolism to ammonia). Strains of commensal viridans streptococci exhibited PRP degradation and Arg catabolism, whereas cariogenic species did not. The RGRPQ peptide mediated via a differential Q-dependent sequence motif, adhesion inhibition, and desorption of PRP-1-binding strains of A. naeslundii genospecies 2 (5 of 10 strains) but not of S. gordonii (n=5). The inhibitable A. naeslundii strains alone displayed the same binding profile as S. gordonii to hybrid peptides terminating in RGRPQ or GQSPQ, derived from the middle or C-terminal segments of PRP-1. The present findings indicate the presence of a host-bacterium interaction in which a host peptide released by bacterial proteolysis affects key properties in biofilm formation.
|
|
| 5. |
- Månsson, Viktor, et al.
(författare)
-
Capsule typing of haemophilus influenzae by matrix-assisted laser Desorption/Ionization time-of-flight mass spectrometry
- 2018
-
Ingår i: Emerging Infectious Diseases. - : Centers for Disease Control and Prevention (CDC). - 1080-6040 .- 1080-6059. ; 24:3, s. 443-452
-
Tidskriftsartikel (refereegranskat)abstract
- Encapsulated Haemophilus influenzae strains belong to type-specific genetic lineages. Reliable capsule typing requires PCR, but a more efficient method would be useful. We evaluated capsule typing by using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. Isolates of all capsule types (a–f and nontypeable; n = 258) and isogenic capsule transformants (types a-d) were investigated. Principal component and biomarker analyses of mass spectra showed clustering, and mass peaks correlated with capsule type-specific genetic lineages. We used 31 selected isolates to construct a capsule typing database. Validation with the remaining isolates (n = 227) showed 100% sensitivity and 92.2% specificity for encapsulated strains (a–f; n = 61). Blinded validation of a supplemented database (n = 50) using clinical isolates (n = 126) showed 100% sensitivity and 100% specificity for encapsulated strains (b, e, and f; n = 28). MALDI-TOF mass spectrometry is an accurate method for capsule typing of H. influenzae.
|
|
| 6. |
- Singh, Birendra, et al.
(författare)
-
Protein E of Haemophilus influenzae Is a Ubiquitous Highly Conserved Adhesin.
- 2010
-
Ingår i: Journal of Infectious Diseases. - : Oxford University Press (OUP). - 1537-6613 .- 0022-1899. ; 201, s. 414-419
-
Tidskriftsartikel (refereegranskat)abstract
- Protein E (PE) of nontypeable Haemophilus influenzae (NTHi) is involved in adhesion and activation of epithelial cells. A total of 186 clinical NTHi isolates, encapsulated H. influenzae, and culture collection strains were analyzed. PE was highly conserved in both NTHi and encapsulated H. influenzae (96.9%-100% identity without the signal peptide). PE also existed in other members of the genus Pasteurellaceae. The epithelial cell binding region (amino acids 84-108) was completely conserved. Phylogenetic analysis of the pe sequence separated Haemophilus species into 2 separate clusters. Importantly, PE was expressed in 98.4% of all NTHi (126 isolates) independently of the growth phase.
|
|
| 7. |
- Sjölinder, Hong, et al.
(författare)
-
Important role for Toll-like receptor 9 in host defense against meningococcal sepsis
- 2008
-
Ingår i: Infection and Immunity. - 0019-9567 .- 1098-5522. ; 76:11, s. 5421-8
-
Tidskriftsartikel (refereegranskat)abstract
- Neisseria meningitidis is a leading cause of meningitis and sepsis. The pathogenesis of meningococcal disease is determined by both bacterial virulence factors and the host inflammatory response. Toll-like receptors (TLRs) are prominent activators of the inflammatory response, and TLR2, -4, and -9 have been reported to be involved in the host response to N. meningitidis. While TLR4 has been suggested to play an important role in early containment of infection, the roles of TLR2 and TLR9 in meningococcal disease are not well described. Using a model for meningococcal sepsis, we report that TLR9(-/-) mice displayed reduced survival and elevated levels of bacteremia compared to wild-type mice. In contrast, TLR2(-/-) mice controlled the infection in a manner comparable to that of wild-type mice. TLR9 deficiency was also associated with reduced bactericidal activity in vitro, which was accompanied by reduced production of nitric oxide by TLR9-deficient macrophages. Interestingly, TLR9(-/-) mice recruited more macrophages to the bloodstream than wild-type mice and produced elevated levels of cytokines at late time points during infection. At the cellular level, activation of signal transduction and induction of cytokine gene expression were independent of TLR2 or TLR9 in macrophages and conventional dendritic cells. In contrast, plasmacytoid dendritic cells relied entirely on TLR9 to induce these activities. Thus, our data demonstrate an important role for TLR9 in host defense against N. meningitidis.
|
|
