Effect of the polysaccharide capsule and its heptose on the resistance of Campylobacter jejuni to innate immune defenses.

Campylobacter jejuni is a commensal in many animals but causes diarrhea in humans. Its polysaccharide capsule contributes to host colonization and virulence in a strain- and model-specific manner. We investigated if the capsule and its heptose are important for interactions of strain NCTC 11168 with various hosts and their innate immune defenses. We determined that they support bacterial survival in Drosophila melanogaster and enhance virulence in Galleria mellonella. We showed that the capsule had limited antiphagocytic activity in human and chicken macrophages, decreased adherence to chicken macrophages, and decreased intracellular survival in both macrophages. In contrast, the heptose increased uptake by chicken macrophages and supported adherence to human macrophages and survival within them. While the capsule triggered nitric oxide production in chicken macrophages, the heptose mitigated this and protected against nitrosative assault. Finally, the C. jejuni strain NCTC 11168 elicited strong cytokine production in both macrophages but quenched ROS production independently from capsule and heptose, and while the capsule and heptose did not protect against oxidative assault, they favored growth in biofilms under oxidative stress. This study shows that the wild-type capsule with its heptose is optimized to resist innate defenses in strain NCTC 11168 often via antagonistic effects of the capsule and its heptose.

In Vitro Framework to Assess the Anti-Helicobacter pylori Potential of Lactic Acid Bacteria Secretions as Alternatives to Antibiotics.

Helicobacter pylori is a prevalent bacterium that can cause gastric ulcers and cancers. Lactic acid bacteria (LAB) ameliorate treatment outcomes against H. pylori, suggesting that they could be a source of bioactive molecules usable as alternatives to current antibiotics for which resistance is mounting. We developed an in vitro framework to compare the anti-H. pylori properties of 25 LAB and their secretions against H. pylori. All studies were done at acidic and neutralized pH, with or without urea to mimic various gastric compartments. Eighteen LAB strains secreted molecules that curtailed the growth of H. pylori and the activity was urea-resistant in five LAB. Several LAB supernatants also reduced the urease activity of H. pylori. Pre-treatment of H. pylori with acidic LAB supernatants abrogated its flagella-mediated motility and decreased its ability to elicit pro-inflammatory IL-8 cytokine from human gastric cells, without reverting the H. pylori-induced repression of other pro-inflammatory cytokines. This study identified the LAB that have the most anti-H. pylori effects, decreasing its viability, its production of virulence factors, its motility and/or its ability to elicit pro-inflammatory IL-8 from gastric cells. Once identified, these molecules can be used as alternatives or complements to current antibiotics to fight H. pylori infections.

Isolated Abducens Palsy as the First Presenting Sign of Multiple Sclerosis.

While brain stem involvement in multiple sclerosis (MS) is relatively common, isolated cranial nerve palsies are rare, especially when they represent the initial presenting sign of a new diagnosis of MS. This report describes a patient with no prior history of MS whose sole presenting sign was an isolated abducens palsy. An enhancing pontine lesion was found on MRI which correlated with his abducens palsy, and additional nonactive lesions on MRI led to a diagnosis of MS. This case demonstrates the importance of considering MS as part of the differential diagnosis of patients with isolated cranial nerve palsies.