322 research outputs found
Comparison of fusobacterium nucleatum and porphyromonas gingivalis lipopolysaccharides clinically isolated from root canal infection in the induction of pro-inflammatory cytokines secretion
The aim of this study was to compare the biological activity of lipopolysaccharides (LPS) purified from Fusobacterium nucleatum and Porphyromonas gingivalis strains, both isolated from primary endodontic infection (PEI) in the levels of IL-1ÎČ and TNF-α released by macrophage cells. Moreover, LPS was purified from F. nucleatum and P. gingivalis American Type Collection (ATCC) and its biological activity was compared to respectively clinical isolates strains. F. nucleatum and P. gingivalis strains clinically isolated from PEI had their identification confirmed by sequencing the 16S rRNA gene. LPS from F. nucleatum and P. gingivalis and their respective ATCC strains were extracted by using Tri-reagent method. Macrophages (Raw 264.7) were stimulated with LPS at 100 ng/mL for 4, 8 and 12 h. Secretion of IL-1 ÎČ and TNF-α was also determined. Paired t-test, repeated measures ANOVA and one-way ANOVA were employed. All LPS induced significant production of IL-1ÎČ and TNF-α, with the former being secreted at higher levels than the latter in all time-points. F. nucleatum induced a higher expression of both cytokines compared to P. gingivalis (p<0.05). No differences were observed between clinical and ATCC strains, as both presented the same potential to induce pro-inflammatory response. It was concluded that F. nucleatum and P. gingivalis LPS presented different patterns of activation against macrophages as seen by the IL-1ÎČ and TNF-α production, which may contribute to the immunopathogenesis of apical periodontitis. Moreover, clinical and ATCC strains grown under the same in vitro environment conditions presented similar biological activity272202207CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTĂFICO E TECNOLĂGICO - CNPQFUNDAĂĂO DE AMPARO Ă PESQUISA DO ESTADO DE SĂO PAULO - FAPESP302575/2009-0; 150557/2011-6; 308162/2014-510/19136-1; 10/17877- 4; 11/50051-5; 11/50510-0; 11/09047-4O objetivo deste estudo foi comparar a atividade biolĂłgica de lipopolissacarĂdeos (LPS) purificados a partir de linhagens de Fusobacterium nucleatum e Porphyromonas gingivalis, ambas isoladas de infecçÔes endodĂŽnticas primĂĄrias (IEP) nos nĂveis de IL-1ÎČ e TNF-α produzidos por macrĂłfagos. Adicionalmente, LPS foi purificado de F. nucleatum e P. gingivalis "American Type Collection" (ATCC) e sua atividade comparada Ă s respectivas linhagens clinicamente isoladas. Linhagens de F. nucleatum e P. gingivalis isoladas clinicamente de IEP tiveram sua identificação confirmada por sequenciamento do gene 16S rRNA. LPS de F. nucleatum e P. gingivalis e das respectivas linhagens foram extraĂdos com o uso do mĂ©todo "Tri-reagent". MacrĂłfagos (Raw 264.7) foram estimulados com LPS a 100 ng/mL por 4, 8 e 12 h. A secreção de IL-1ÎČ e de TNF-α foi determinada. Foram usados os testes t-pareado, ANOVA de medidas repetidas e ANOVA de um fator. Todos os LPS induziram a produção significante de IL-1ÎČ e TNF-α, sendo o primeiro secretado em mais altas concentraçÔes que o Ășltimo em todos os tempos avaliados. F. nucleatum induziu uma maior expressĂŁo de ambas as citocinas comparativamente ao P. gingivalis (p<0,05). NĂŁo foram observadas diferenças entre as linhagens clĂnica e ATCC, uma vez que ambas apresentaram o mesmo potencial de indução da resposta prĂł-inflamatĂłria. Conclui-se que F. nucleatum e P. gingivalis possuem diferentes padrĂ”es de ativação dos macrĂłfagos, como visto pela produção de IL-1ÎČ e TNF-α, o que pode contribuir para a imunopatogĂȘnese da periodontite apical. Ainda, linhagens clĂnica e ATCC mantidas no mesmo ambiente in vitro apresentaram ativação biolĂłgica semelhant
Macrophage Subset Sensitivity to Endotoxin Tolerisation by Porphyromonas gingivalis
Macrophages (MΊs) determine oral mucosal responses; mediating tolerance to commensal microbes and food whilst maintaining the capacity to activate immune defences to pathogens. MΊ responses are determined by both differentiation and activation stimuli, giving rise to two distinct subsets; pro-inflammatory M1- and anti-inflammatory/regulatory M2- MΊs. M2-like subsets predominate tolerance induction whereas M1 MΊs predominate in inflammatory pathologies, mediating destructive inflammatory mechanisms, such as those in chronic P.gingivalis (PG) periodontal infection. MΊ responses can be suppressed to benefit either the host or the pathogen. Chronic stimulation by bacterial pathogen associated molecular patterns (PAMPs), such as LPS, is well established to induce tolerance. The aim of this study was to investigate the susceptibility of MΊ subsets to suppression by P. gingivalis. CD14hi and CD14lo M1- and M2-like MΊs were generated in vitro from the THP-1 monocyte cell line by differentiation with PMA and vitamin D3, respectively. MΊ subsets were pre-treated with heat-killed PG (HKPG) and PG-LPS prior to stimulation by bacterial PAMPs. Modulation of inflammation was measured by TNFα, IL-1ÎČ, IL-6, IL-10 ELISA and NFÎșB activation by reporter gene assay. HKPG and PG-LPS differentially suppress PAMP-induced TNFα, IL-6 and IL-10 but fail to suppress IL-1ÎČ expression in M1 and M2 MΊs. In addition, P.gingivalis suppressed NFÎșB activation in CD14lo and CD14hi M2 regulatory MΊs and CD14lo M1 MΊs whereas CD14hi M1 pro-inflammatory MΊs were refractory to suppression. In conclusion, P.gingivalis selectively tolerises regulatory M2 MΊs with little effect on pro-inflammatory CD14hi M1 MΊs; differential suppression facilitating immunopathology at the expense of immunity
Homogeneous search for helium in the atmosphere of 11 gas giant exoplanets with SPIRou
The metastable helium triplet in the near-infrared (10833{\AA}) is among the
most important probes of exoplanet atmospheres. It can trace their extended
outer layers and constrain mass-loss. We use the near-infrared high-resolution
spectropolarimeter SPIRou on the CFHT to search for the spectrally resolved
helium triplet in the atmospheres of eleven exoplanets, ranging from warm
mini-Neptunes to hot Jupiters and orbiting G, K, and M dwarfs. Observations
were obtained as part of the SPIRou Legacy Survey and complementary open-time
programs. We apply a homogeneous data reduction to all datasets and set
constraints on the presence of metastable helium, despite the presence of
systematics in the data. We confirm published detections for HAT-P-11b,
HD189733b, and WASP-69b and set upper limits for the other planets. We apply
the p-winds open source code to set upper limits on the mass-loss rate for the
non-detections and to constrain the thermosphere temperature, mass-loss rate,
line-of-sight velocity, and the altitude of the thermosphere for the
detections. We confirm that the presence of metastable helium correlates with
the stellar mass and the XUV flux received by the planets. We investigated the
correlation between the mass-loss rate and the presence of metastable helium,
but it remains difficult to draw definitive conclusions. Finally, some of our
results are in contradiction with previous results in the literature, therefore
we stress the importance of repeatable, homogeneous, and larger-scale analyses
of the helium triplet to obtain robust statistics, study temporal variability,
and better understand how the helium triplet can be used to explore the
evolution of exoplanets.Comment: 28 pages, 13 figures, Accepted in A&A for publicatio
A Bioeconomic Foundation for the Nutrition-Based Efficiency Wage Model
Drawing on recent research on allometric scaling and energy consumption, the present paper develops a nutrition-based efficiency wage model from first principles. The biologically micro-founded model allows us to address empirical criticism of the original nutrition-based efficiency wage model. By extending the model with respect to heterogeneity in worker body size and a physiologically founded impact of body size on productivity, we demonstrate that the nutrition-based efficiency wage model is compatible with the empirical regularity that taller workers simultaneously earn higher wages and are less likely to be unemployed in less developed economies. The theory also provides an answer to the question of why such regularity may disappear in the process of development
Global and regional brain metabolic scaling and its functional consequences
Background: Information processing in the brain requires large amounts of
metabolic energy, the spatial distribution of which is highly heterogeneous
reflecting complex activity patterns in the mammalian brain.
Results: Here, it is found based on empirical data that, despite this
heterogeneity, the volume-specific cerebral glucose metabolic rate of many
different brain structures scales with brain volume with almost the same
exponent around -0.15. The exception is white matter, the metabolism of which
seems to scale with a standard specific exponent -1/4. The scaling exponents
for the total oxygen and glucose consumptions in the brain in relation to its
volume are identical and equal to , which is significantly larger
than the exponents 3/4 and 2/3 suggested for whole body basal metabolism on
body mass.
Conclusions: These findings show explicitly that in mammals (i)
volume-specific scaling exponents of the cerebral energy expenditure in
different brain parts are approximately constant (except brain stem
structures), and (ii) the total cerebral metabolic exponent against brain
volume is greater than the much-cited Kleiber's 3/4 exponent. The
neurophysiological factors that might account for the regional uniformity of
the exponents and for the excessive scaling of the total brain metabolism are
discussed, along with the relationship between brain metabolic scaling and
computation.Comment: Brain metabolism scales with its mass well above 3/4 exponen
Baicalin Downregulates Porphyromonas gingivalis Lipopolysaccharide-Upregulated IL-6 and IL-8 Expression in Human Oral Keratinocytes by Negative Regulation of TLR Signaling
published_or_final_versio
Role of Porphyromonas gingivalis gingipains in multi-species biofilm formation
BackgroundPeriodontal diseases are polymicrobial diseases that cause the inflammatory destruction of the tooth-supporting (periodontal) tissues. Their initiation is attributed to the formation of subgingival biofilms that stimulate a cascade of chronic inflammatory reactions by the affected tissue. The Gram-negative anaerobes Porphyromonas gingivalis, Tannerella forsythia and Treponema denticola are commonly found as part of the microbiota of subgingival biofilms, and they are associated with the occurrence and severity of the disease. P. gingivalis expresses several virulence factors that may support its survival, regulate its communication with other species in the biofilm, or modulate the inflammatory response of the colonized host tissue. The most prominent of these virulence factors are the gingipains, which are a set of cysteine proteinases (either Arg-specific or Lys-specific). The role of gingipains in the biofilm-forming capacity of P. gingivalis is barely investigated. Hence, this in vitro study employed a biofilm model consisting of 10 ÂżsubgingivalÂż bacterial species, incorporating either a wild-type P. gingivalis strain or its derivative Lys-gingipain and Arg-gingipan isogenic mutants, in order to evaluate quantitative and qualitative changes in biofilm composition.ResultsFollowing 64Â h of biofilm growth, the levels of all 10 species were quantified by fluorescence in situ hybridization or immunofluorescence. The wild-type and the two gingipain-deficient P. gingivalis strains exhibited similar growth in their corresponding biofilms. Among the remaining nine species, only the numbers of T. forsythia were significantly reduced, and only when the Lys-gingipain mutant was present in the biofilm. When evaluating the structure of the biofilm by confocal laser scanning microscopy, the most prominent observation was a shift in the spatial arrangement of T. denticola, in the presence of P. gingivalis Arg-gingipain mutant.ConclusionsThe gingipains of P. gingivalis may qualitatively and quantitatively affect composition of polymicrobial biofilms. The present experimental model reveals interdependency between the gingipains of P. gingivalis and T. forsythia or T. denticola
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