Glycerol Supplementation Enhances L. reuteri’s Protective Effect against S. Typhimurium Colonization in a 3-D Model of Colonic Epithelium

The probiotic effects of Lactobacillus reuteri have been speculated to partly depend on its capacity to produce the antimicrobial substance reuterin during the reduction of glycerol in the gut. In this study, the potential of this process to protect human intestinal epithelial cells against infection with Salmonella enterica serovar Typhimurium was investigated. We used a three-dimensional (3-D) organotypic model of human colonic epithelium that was previously validated and applied to study interactions between S. Typhimurium and the intestinal epithelium that lead to enteric salmonellosis. Using this model system, we show that L. reuteri protects the intestinal cells against the early stages of Salmonella infection and that this effect is significantly increased when L. reuteri is stimulated to produce reuterin from glycerol. More specifically, the reuterin-containing ferment of L. reuteri caused a reduction in Salmonella adherence and invasion (1 log unit), and intracellular survival (2 log units). In contrast, the L. reuteri ferment without reuterin stimulated growth of the intracellular Salmonella population with 1 log unit. The short-term exposure to reuterin or the reuterin-containing ferment had no observed negative impact on intestinal epithelial cell health. However, long-term exposure (24 h) induced a complete loss of cell-cell contact within the epithelial aggregates and compromised cell viability. Collectively, these results shed light on a potential role for reuterin in inhibiting Salmonella-induced intestinal infections and may support the combined application of glycerol and L. reuteri. While future in vitro and in vivo studies of reuterin on intestinal health should fine-tune our understanding of the mechanistic effects, in particular in the presence of a complex gut microbiota, this the first report of a reuterin effect on the enteric infection process in any mammalian cell type

#parlezvousfrançais? Exploring the Use of Twitter in Language Courses

In this presentation, I will talk about a semester-long Twitter activity that I have designed for a Second-Semester French course. For this assignment, students are asked to write messages on their daily lives, tastes or future plans, and to respond to others\u27. This activity is easy to set up and can be adapted to different languages and levels. As the first semesters of language courses are content heavy and highly structured, Twitter offers students the opportunity to use the target language in a casual and playful way. Linguistically, tweeting about daily life allows beginners to practice basic vocabulary and grammar structures. This activity also teaches useful cultural phrases such as “I can\u27t wait” or “I\u27m excited.” Beyond reinforcing practice, tweeting increases the learning outcomes by fostering language use in a fun and life-relevant way and by strengthening students\u27 personal relationship with the material studied. This activity also enhances users\u27 confidence in their abilities to communicate in the target language. Finally, it helps develop a sense of community and a positive atmosphere among learners, especially when several classes are involved. In my presentation, I will expose the curricular concerns that led me to create this activity, and how I structure and grade it. I will also explore its learning benefits, as well as its logistical and pedagogical challenges. Finally, I will suggest variations on this assignment and changes that I plan to make when assigning this activity in the future. I will illustrate my comments with examples of students\u27 tweets and reactions to this exercise

De la négation absolue à la révolte : la théorie camusienne illustrée par la poétique des Fleurs du mal

Dans son essai L’Homme révolté (1951), Camus distingue deux types de révolte : la révolte métaphysique et la révolte historique. Je m’intéresserai ici à la première, que le penseur définit comme « la revendication motivée d’une unité heureuse, contre la souffrance de vivre et de mourir » (OC III, 81). En littérature, Camus prend pour exemple de cette réaction la poésie surréaliste, inspirée de la voyance rimbaldienne. En amont de la révolte métaphysique, il pose l’attitude de « négation absol..

Overview of the bacterial strains used in this study.

¶<p>: <i>pduC</i>: HMPREF0536_1321. Resultant amino acid changes after incorporation of the oligonucleotide are listed after each gene, and X represents a stop codon.</p

The <i>L. reuteri</i> supernatants affected the <i>S.</i> Typhimurium χ3339 population stronger in the presence of the 3-D HT-29 aggregates.

<p>Log counts (CFU.mL⁻¹) of the χ3339 population (initial inoculum 2×10⁶ cells.mL⁻¹) exposed to the 10-fold diluted supernatant without (SN- 1∶10) and with reuterin (SN+1∶10, 2.5 mM 3-HPA) both in the absence (left) and presence (right) of 3-D HT-29 aggregates. Detection limit = 10² CFU.mL⁻¹.</p

3-HPA and the 10-fold diluted reuterin-containing supernatant significantly decreased the <i>S.</i> Typhimurium χ3339 population.

<p>Log difference in χ3339 counts (CFU.mL⁻¹) of the untreated χ3339 control minus the treatments with 3 mM 3-HPA, the 10-, 100- or 1000-fold diluted supernatants containing reuterin (respectively SN+1∶10 with 2.5 mM 3-HPA, SN+1∶100; 0.25 mM 3-HPA and SN+1∶1000; 0.025 mM 3-HPA) and the 10-fold diluted supernatant without reuterin (SN- 1∶10) after 1, 4 and 24 h of exposure. Significant differences between the treatments are indicated with different letters (a or b; p<0.05).</p

The 10-fold diluted reuterin-containing supernatant decreased <i>S.</i> Typhimurium χ3339 colonization in 3-D HT-29 aggregates, while the supernatant without reuterin stimulated χ3339 intracellular survival and growth.

<p>Log difference in χ3339 counts (CFU.mL⁻¹) of the untreated χ3339 control minus the treatments with 3 mM 3-HPA, the 10-, 100- and 1000-fold diluted supernatants containing reuterin (respectively SN+1∶10 with 2.5 mM 3-HPA, SN+1∶100; 0.25 mM 3-HPA and SN+1∶1000; 0.025 mM 3-HPA) and the 10-fold diluted supernatant without reuterin (SN- 1∶10) after 1 h (adhesion & invasion), 4 h (intracellular survival) and 24 h (intracellular growth) of exposure. The non-invasive <i>E. coli</i> HB101 control strain did not show countable colonies at the lowest dilution (detection limit = 10² CFU.mL⁻¹). Significant differences between the treatments are indicated with different letters (a, b, c or d; p<0.05). <i>bdl</i> = below detection limit.</p

Experimental procedure for infection of 3-D HT-29 aggregates with <i>S.</i> Typhimurium χ3339 (red line).

<p>Approach 1 infection experiments were done in the presence of supernatants of the <i>L. reuteri</i> ferment with or without reuterin (green star), while approach 2 infections were done in the presence of an established <i>L. reuteri</i> population (blue line) producing reuterin <i>in situ</i>.</p