High-Fat Diet Induces Periodontitis in Mice through Lipopolysaccharides (LPS) Receptor Signaling: Protective Action of Estrogens

<div><h3>Background</h3><p>A fat-enriched diet favors the development of gram negative bacteria in the intestine which is linked to the occurrence of type 2 diabetes (T2D). Interestingly, some pathogenic gram negative bacteria are commonly associated with the development of periodontitis which, like T2D, is characterized by a chronic low-grade inflammation. Moreover, estrogens have been shown to regulate glucose homeostasis <em>via</em> an LPS receptor dependent immune-modulation. In this study, we evaluated whether diet-induced metabolic disease would favor the development of periodontitis in mice. In addition, the regulatory role of estrogens in this process was assessed.</p> <h3>Methods</h3><p>Four-week-old C57BL6/J WT and CD14 (part of the TLR-4 machinery for LPS-recognition) knock-out female mice were ovariectomised and subcutaneously implanted with pellets releasing either placebo or 17β-estradiol (E2). Mice were then fed with either a normal chow or a high-fat diet for four weeks. The development of diabetes was monitored by an intraperitoneal glucose-tolerance test and plasma insulin concentration while periodontitis was assessed by identification of pathogens, quantification of periodontal soft tissue inflammation and alveolar bone loss.</p> <h3>Results</h3><p>The fat-enriched diet increased the prevalence of periodontal pathogenic microbiota like <em>Fusobacterium nucleatum</em> and <em>Prevotella intermedia</em>, gingival inflammation and alveolar bone loss. E2 treatment prevented this effect and CD14 knock-out mice resisted high-fat diet-induced periodontal defects.</p> <h3>Conclusions/Significance</h3><p>Our data show that mice fed with a diabetogenic diet developed defects and microflora of tooth supporting-tissues typically associated with periodontitis. Moreover, our results suggest a causal link between the activation of the LPS pathway on innate immunity by periodontal microbiota and HFD-induced periodontitis, a pathophysiological mechanism that could be targeted by estrogens.</p> </div

Positive bacterial cultures : intergroup comparisons among ovariectomised mice.

1<p>Fischer exact tests p-values, significant at p<0.05.</p><p>The table shows the qualitative analysis of periodontal microbiota in each group: WT OVX+NCD (n = 27), WT OVX+HFD (n = 25), WT OVX+HFD+E2 (n = 25) and <i>CD14</i>KO OVX+HFD (n = 12).</p>*<p>P<0.05,</p>**<p>P<0.01 (Fischer exact tests).</p

HFD-fed <i>CD14</i>KO mice did not exhibit metabolic disorders compared with WT. A)

<p>Body weight was assessed in 8-wk-old mice after 4 weeks of diet : WT OVX+HFD (n = 10), WT OVX+HFD+E2 (n = 10), CD14KO OVX+HFD (n = 12) and CD14KO OVX+HFD+E2 (n = 12). <b>B</b>) Time course of glycemia (mg/dl) during an IPGTT. The inset represents the glycemic index for each group. <b>C</b>) Fasted plasma insulin concentration (µg/l) after 4 weeks of diet : WT OVX+HFD (n = 6), WT OVX+HFD+E2 (n = 6), CD14KO OVX+HFD (n = 6) and CD14KO OVX+HFD+E2 (n = 6). *P<0.05, **P<0.01 (One-way ANOVA followed by Tukey’s post-test for <b>A</b> and <b>C</b>; and Two-Way ANOVA with Bonferroni’s post-test for <b>B</b>). Results are presented as means ± SEM.</p

HFD induced periodontal disease in WT mice: reversal effect of E2-treatment. A)

<p>The occurrence of periodontal pathogens was analysed in 8-wk-old mice after 4 weeks of diet : WT OVX+NCD (n = 27), WT OVX+NCD+E2 (n = 16), WT OVX+HFD (n = 15) and WT OVX+HFD+E2 (n = 15). <b>B–G</b>) Hemi-mandible from each group, as reconstructed by the micro-CT. <b>F</b>) CEJ (red line: cemento-enamel junction)-ABC (green line: alveolar bone crest) distance to represent alveolar bone loss (yellow line) (n = 8 for each group). *P<0.05, **P<0.01, ***P<0.001 (one-way ANOVA followed by Tukey test). Results are presented as means ± SEM.</p

HFD-fed <i>CD14</i>KO mice are protected from periodontal disease compared with WT. A

<p>) The occurrence of periodontal pathogens was analyzed in 8-wk-old mice after 4 weeks of diet: WT OVX+HFD (n = 10), WT OVX+HFD+E2 (n = 10), CD14KO OVX+HFD (n = 12) and CD14KO OVX+HFD+E2 (n = 12). <b>B–G</b>) Hemi-mandible from each group, as reconstructed by the micro-CT. <b>F</b> CEJ (red line: cemento-enamel junction)-ABC (green line: alveolar bone crest) distance to represent alveolar bone loss (yellow line). *P<0.05, **P<0.01, ***P<0.001 (one-way ANOVA followed by Tukey test). Results are presented as means ± SEM.</p

<i>CD14</i>KO mice did not display HFD-induced periodontal inflammation.

<p>mRNA expression of TNF-α (<b>A</b>), IL-1β (<b>B</b>), PAI-1(<b>C</b>) and IL-6 (<b>D</b>) in gingival tissue. *P<0.05, **P<0.01,***P<0.001 (one-way ANOVA followed by Tukey test). Results are presented as means ± SEM.</p

E2 decreases the expression of gingival inflammatory mediators in HFD-fed ovariectomised (OVX) mice.

<p>mRNA synthesis of TNF-α (<b>A</b>), IL-1β (<b>B</b>), PAI-1(<b>C</b>) and IL-6 (<b>D</b>) in gingival tissue. *P<0.05, **P<0.01, ***P<0.001 (one-way ANOVA followed by Tukey test). Results are presented as means ± SEM.</p

Associations of microvascular complications with all-cause death in patients with diabetes and COVID-19: The CORONADO, ABCD COVID-19 UK national audit and AMERICADO study groups

Aim To provide a detailled analysis of the microvascular burden in patients with diabetes hopitalized for COVD-19. Materials and Methods We analysed data from the French CORONADO initiative and the UK Association of British Clinical Diabetologists (ABCD) COVID-19 audit, two nationwide multicentre studies, and the AMERICADO, a multicentre study conducted in New York area. We assessed the association between risk of all-cause death during hospital stay and the following microvascular complications in patients with diabetes hospitalized for COVID-19: diabetic retinopathy and/or diabetic kidney disease and/or history of diabetic foot ulcer. Results Among 2951 CORONADO, 3387 ABCD COVID-19 audit and 9327 AMERICADO participants, microvascular diabetic complications status was ascertained for 1314 (44.5%), 1809 (53.4%) and 7367 (79.0%) patients, respectively: 1010, 1059 and 1800, respectively, had ≥1 severe microvascular complication(s) and 304, 750 and 5567, respectively, were free of any complications. The patients with isolated diabetic kidney disease had an increased risk of all-cause death during hospital stay: odds ratio [OR] 2.53 (95% confidence interval [CI] 1.66-3.83), OR 1.24 (95% CI 1.00-1.56) and OR 1.66 (95% CI 1.40-1.95) in the CORONADO, the ABCD COVID-19 national audit and the AMERICADO studies, respectively. After adjustment for age, sex, hypertension and cardiovascular disease (CVD), compared to those without microvascular complications, patients with microvascular complications had an increased risk of all-cause death during hospital stay in the CORONADO, the ABCD COVID-19 diabetes national audit and the AMERICADO studies: adjusted OR (adjOR) 2.57 (95% CI 1.69-3.92), adjOR 1.22 (95% CI 1.00-1.52) and adjOR 1.33 (95% CI 1.15-1.53), respectively. In meta-analysis of the three studies, compared to patients free of complications, those with microvascular complications had an unadjusted OR for all-cause death during hospital stay of 2.05 (95% CI 1.42-2.97), which decreased to 1.62 (95% CI 1.19-2.119) after adjustment for age and sex, and to 1.50 (1.12-2.02) after hypertension and CVD were further added to the model. Conclusion Microvascular burden is associated with an increased risk of death in patients hospitalized for COVID-19.</p

The depletion of <i>CD14</i> reduced HFD-induced inflammatory cell infiltration into gingival connective tissue.

<p>Histological appearance of the gingival tissues with H/E coloration from WT OVX+HFD (<b>A,</b> n = 6), <i>CD14</i>KO OVX+HFD (<b>B,</b> n = 6) WT OVX+HFD+E2 (<b>C,</b> n = 6), and <i>CD14</i>KO OVX+HFD+E2 (<b>D,</b> n = 6) <b>E</b>. Number of inflammatory cells for each group. *P<0.05,**P<0.01, ***P<0.001 (one-way ANOVA followed by Tukey test). Results are presented as means ± SEM.</p

DataSheet_1_Membrane estrogen receptor-α contributes to female protection against high-fat diet-induced metabolic disorders.pdf

BackgroundEstrogen Receptor α (ERα) is a significant modulator of energy balance and lipid/glucose metabolisms. Beyond the classical nuclear actions of the receptor, rapid activation of intracellular signaling pathways is mediated by a sub-fraction of ERα localized to the plasma membrane, known as Membrane Initiated Steroid Signaling (MISS). However, whether membrane ERα is involved in the protective metabolic actions of endogenous estrogens in conditions of nutritional challenge, and thus contributes to sex differences in the susceptibility to metabolic diseases, remains to be clarified.MethodsMale and female C451A-ERα mice, harboring a point mutation which results in the abolition of membrane localization and MISS-related effects of the receptor, and their wild-type littermates (WT-ERα) were maintained on a normal chow diet (NCD) or fed a high-fat diet (HFD). Body weight gain, body composition and glucose tolerance were monitored. Insulin sensitivity and energy balance regulation were further investigated in HFD-fed female mice.ResultsC451A-ERα genotype had no influence on body weight gain, adipose tissue accumulation and glucose tolerance in NCD-fed mice of both sexes followed up to 7 months of age, nor male mice fed a HFD for 12 weeks. In contrast, compared to WT-ERα littermates, HFD-fed C451A-ERα female mice exhibited: 1) accelerated fat mass accumulation, liver steatosis and impaired glucose tolerance; 2) whole-body insulin resistance, assessed by hyperinsulinemic-euglycemic clamps, and altered insulin-induced signaling in skeletal muscle and liver; 3) significant decrease in energy expenditure associated with histological and functional abnormalities of brown adipose tissue and a defect in thermogenesis regulation in response to cold exposure.ConclusionBesides the well-characterized role of ERα nuclear actions, membrane-initiated ERα extra-nuclear signaling contributes to female, but not to male, protection against HFD-induced obesity and associated metabolic disorders in mouse.</p