Humoral Immunity to Stress Proteins and Periodontal Disease

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141026/1/jper1185.pd

Cellular localization of a Hsp90 homologue in Porphyromonas gingivalis

We previously reported an association between elevated serum antibody titers to the 90-kDa human heat shock protein (Hsp90), periodontal health and colonization by Porphyromonas gingivalis . In this study, we examined the cellular localization of the Hsp90 homologue of P. gingivalis . Cultures of P. gingivalis were heat-stressed (45°C) and examined for localization of the Hsp90 homologue. Heat stress induced a 4–5-fold increase in anti-Hsp90 antibody reactivity over that of the unstressed controls. Western blot analysis revealed two bands (44 and 68 kDa) that reacted with anti-Hsp90 antibodies. The 68-kDa band was heat-inducible, while the 44-kDa band was not. Immunogold staining revealed that the Hsp90 homologue localized principally to the membrane and extracellular vesicles. Subcellular fractionation confirmed that the Hsp90 homologue was primarily membrane-associated.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72856/1/j.1574-6968.1999.tb08820.x.pd

Clinical Impact of Ceftriaxone Resistance in Escherichia coli Bloodstream Infections: A Multicenter Prospective Cohort Study

BACKGROUND: Ceftriaxone-resistant (CRO-R) Escherichia coli bloodstream infections (BSIs) are common. METHODS: This is a prospective cohort of patients with E coli BSI at 14 United States hospitals between November 2020 and April 2021. For each patient with a CRO-R E coli BSI enrolled, the next consecutive patient with a ceftriaxone-susceptible (CRO-S) E coli BSI was included. Primary outcome was desirability of outcome ranking (DOOR) at day 30, with 50% probability of worse outcomes in the CRO-R group as the null hypothesis. Inverse probability weighting (IPW) was used to reduce confounding. RESULTS: Notable differences between patients infected with CRO-R and CRO-S E coli BSI included the proportion with Pitt bacteremia score ≥4 (23% vs 15%, P = .079) and the median time to active antibiotic therapy (12 hours [interquartile range {IQR}, 1-35 hours] vs 1 hour [IQR, 0-6 hours]; P \u3c .001). Unadjusted DOOR analyses indicated a 58% probability (95% confidence interval [CI], 52%-63%) for a worse clinical outcome in CRO-R versus CRO-S BSI. In the IPW-adjusted cohort, no difference was observed (54% [95% CI, 47%-61%]). Secondary outcomes included unadjusted and adjusted differences in the proportion of 30-day mortality between CRO-R and CRO-S BSIs (-5.3% [95% CI, -10.3% to -.4%] and -1.8 [95% CI, -6.7% to 3.2%], respectively), postculture median length of stay (8 days [IQR, 5-13 days] vs 6 days [IQR, 4-9 days]; P \u3c .001), and incident admission to a long-term care facility (22% vs 12%, P = .045). CONCLUSIONS: Patients with CRO-R E coli BSI generally have poorer outcomes compared to patients infected with CRO-S E coli BSI, even after adjusting for important confounders

AI is a viable alternative to high throughput screening: a 318-target study

: High throughput screening (HTS) is routinely used to identify bioactive small molecules. This requires physical compounds, which limits coverage of accessible chemical space. Computational approaches combined with vast on-demand chemical libraries can access far greater chemical space, provided that the predictive accuracy is sufficient to identify useful molecules. Through the largest and most diverse virtual HTS campaign reported to date, comprising 318 individual projects, we demonstrate that our AtomNet® convolutional neural network successfully finds novel hits across every major therapeutic area and protein class. We address historical limitations of computational screening by demonstrating success for target proteins without known binders, high-quality X-ray crystal structures, or manual cherry-picking of compounds. We show that the molecules selected by the AtomNet® model are novel drug-like scaffolds rather than minor modifications to known bioactive compounds. Our empirical results suggest that computational methods can substantially replace HTS as the first step of small-molecule drug discovery

Immunoglobulin G (IgG) Class, but Not IgA or IgM, Antibodies to Peptides of the Porphyromonas gingivalis Chaperone HtpG Predict Health in Subjects with Periodontitis by a Fluorescence Enzyme-Linked Immunosorbent Assay▿

Chaperones are molecules found in all cells and are critical in stabilization of synthesized proteins, in repair/removal of defective proteins, and as immunodominant antigens in innate and adaptive immunity. Subjects with gingivitis colonized by the oral pathogen Porphyromonas gingivalis previously demonstrated levels of anti-human chaperone Hsp90 that were highest in individuals with the best oral health. We hypothesized that similar antibodies to pathogen chaperones might be protective in periodontitis. This study examined the relationship between antibodies to P. gingivalis HtpG and clinical statuses of healthy and periodontitis-susceptible subjects. We measured the humoral responses (immunoglobulin G [IgG], IgA, and IgM) to peptides of a unique insert (P18) found in Bacteroidaceae HtpG by using a high-throughput, quantitative fluorescence enzyme-linked immunosorbent assay. Indeed, higher levels of IgG class anti-P. gingivalis HtpG P18 peptide (P < 0.05) and P18α, consisting of the N-terminal 16 amino acids of P18 (P < 0.05), were associated with better oral health; these results were opposite of those found with anti-P. gingivalis whole-cell antibodies and levels of the bacterium in the subgingival biofilm. When we examined the same sera for IgA and IgM class antibodies, we found no significant relationship to subject clinical status. The relationship between anti-P18 levels and clinical populations and individual subjects was found to be improved when we normalized the anti-P18α values to those for anti-P18γ (the central 16 amino acids of P18). That same ratio correlated with the improvement in tissue attachment gain after treatment (P < 0.05). We suggest that anti-P. gingivalis HtpG P18α antibodies are protective in periodontal disease and may have prognostic value for guidance of individual patient treatment

Induction of β-Defensin Resistance in the Oral Anaerobe Porphyromonas gingivalis

Induction of resistance of oral anaerobes to the effects of human β-defensin 1 (hβD-1) to hβD-4 was investigated by pretreating cells with either sublethal levels of defensins or environmental factors, followed by a challenge with lethal levels of defensins. Cultures of Porphyromonas gingivalis were (i) pretreated with defensins at 1 ng/ml, (ii) heated to 42°C (heat stress), (iii) exposed to normal atmosphere (oxidative stress), or (iv) exposed to 1 mM hydrogen peroxide (peroxide stress). Samples (10 μl) were distributed among the wells of sterile 384-well plates containing hβD-1 to -4 (100 μg/ml). Plates were incubated at 37°C for 36 h in an anaerobe chamber. Growth inhibition was determined by a system that measures the total nucleic acid of a sample with a DNA binding dye. The MICs of the four defensins for P. gingivalis were 3 to 12 μg/ml. We found that sublethal levels of the defensins and heat and peroxide stress, but not oxidative stress, induced resistance to 100 μg of defensin per ml in P. gingivalis. Resistance induced by sublethal levels of hβD-2 lasted 90 min, and the resistance induced by each defensin was effective against the other three. Multiple strains exposed to hβD-2 all evidenced resistance induction. Defensin resistance is vital to the pathogenic potential of several human pathogens. This is the first report describing the induction of defensin resistance in the oral periodontal pathogen P. gingivalis. Such resistance may have an effect on the ability of oral pathogens to persist in the mouth and to withstand innate human immunity

Adoptive Behaviors of Farmers After Training and Their Subsequent Diffusive Behaviors In Uasin Gishu County, Kenya

This study focused on Kenyan farmers in the Moiben area who participated in three agricultural seminars at Twiga demonstration farm. The problem of interest was the need for increased dissemination of improved agricultural practices to enhance production and processing of crops related to food security and socio-economic well-being. The study investigated associations between adoptive behaviors of participants and their subsequent behavior related to diffusing improved practices to others. Data was collected using a demographic questionnaire and two structured interview schedules. Correlational analysis was conducted on post-training behavior variables, using Kendall’s tau calculations. The study found that farmers across the samples who exhibited higher levels of adoption of workshop-recommended innovations also had a moderate to strong likelihood of showing correspondingly higher levels of diffusion-related behavior. It was concluded that these findings align well with Rogers’ (2003) discussion of change-agent credibility, and also with Bandura’s (2006) work on social modeling and perceived self-efficacy. It was recommended that offering community-based agricultural seminars such as those in this study be continued and expanded, as an important component in a pluralistic model of agricultural extension methodology for Sub-Saharan Africa. It was further recommended that farmers who adopt improved practices learned in training be identified specifically for further interventions related to implementation and diffusion of agricultural innovations

Serum antibodies to Porphyromonas gingivalis chaperone HtpG predict health in periodontitis susceptible patients.

Chaperones are ubiquitous conserved proteins critical in stabilization of new proteins, repair/removal of defective proteins and immunodominant antigens in innate and adaptive immunity. Periodontal disease is a chronic inflammatory infection associated with infection by Porphyromonas gingivalis that culminates in the destruction of the supporting structures of the teeth. We previously reported studies of serum antibodies reactive with the human chaperone Hsp90 in gingivitis, a reversible form of gingival disease confined to the oral soft tissues. In those studies, antibodies were at their highest levels in subjects with the best oral health. We hypothesized that antibodies to the HSP90 homologue of P. gingivalis (HtpG) might be associated with protection/resistance against destructive periodontitis.ELISA assays using cloned HtpG and peptide antigens confirmed gingivitis subjects colonized with P. gingivalis had higher serum levels of anti-HtpG and, concomitantly, lower levels of attachment loss. Additionally, serum antibody levels to P. gingivalis HtpG protein were higher in healthy subjects compared to patients with either chronic or aggressive periodontitis. We found a negative association between tooth attachment loss and anti-P. gingivalis HtpG (p = 0.043) but not anti-Fusobacterium nucleatum (an oral opportunistic commensal) HtpG levels. Furthermore, response to periodontal therapy was more successful in subjects having higher levels of anti-P. gingivalis HtpG before treatment (p = 0.018). There was no similar relationship to anti-F. nucleatum HtpG levels. Similar results were obtained when these experiments were repeated with a synthetic peptide of a region of P. gingivalis HtpG.OUR RESULTS SUGGEST: 1) anti-P. gingivalis HtpG antibodies are protective and therefore predict health periodontitis-susceptable patients; 2) may augment the host defence to periodontitis and 3) a unique peptide of P. gingivalis HtpG offers significant potential as an effective diagnostic target and vaccine candidate. These results are compatible with a novel immune control mechanism unrelated to direct binding of bacteria