Development of Mass Spectrometry Imaging on skeletal muscle to characterize the local pro-inflammatory and pro-resolution lipid responses in a vaccination context.

Vaccine reactogenicity is well documented at the clinical level but the mechanism involved at the local or systemic level are still poorly understood. Muscular tissue where most vaccines are administered is the first place of interaction between the vaccine formulation and the host's immune cells. So far, this site of vaccine administration is not well documented from a mechanistic standpoint. The study of early molecular events at the injection site is crucial to understand the local response to vaccines. In this paper, we report a standardized workflow, from the injection of vaccine formulations in rabbit muscle, to the analysis by desorption electrospray ionization and histology staining to understand the role of lipids involved in the inflammation and its resolution on striated muscular tissue. The analysis of lipid mediators was optimized at the site of needle insertion to allow the spatial comparison of cellular infiltrates at the injection site. We showed that lipids were distributed across the spatial tissue morphology in a time-dependent manner. The MS imaging applied to vaccinology could pave the way to a better understanding of vaccine reactogenicity and mechanism of action.

The impact of the Fungus-Host-Microbiota interplay upon Candida albicans infections: current knowledge and new perspectives.

Candida albicans is a major fungal pathogen of humans. It exists as a commensal in the oral cavity, gut or genital tract of most individuals, constrained by the local microbiota, epithelial barriers and immune defences. Their perturbation can lead to fungal outgrowth and the development of mucosal infections such as oropharyngeal or vulvovaginal candidiasis, and patients with compromised immunity are susceptible to life-threatening systemic infections. The importance of the interplay between fungus, host and microbiota in driving the transition from C. albicans commensalism to pathogenicity is widely appreciated. However, the complexity of these interactions, and the significant impact of fungal, host and microbiota variability upon disease severity and outcome, are less well understood. Therefore, we summarise the features of the fungus that promote infection, and how genetic variation between clinical isolates influences pathogenicity. We discuss antifungal immunity, how this differs between mucosae, and how individual variation influences a person's susceptibility to infection. Also, we describe factors that influence the composition of gut, oral and vaginal microbiotas, and how these affect fungal colonisation and antifungal immunity. We argue that a detailed understanding of these variables, which underlie fungal-host-microbiota interactions, will present opportunities for directed antifungal therapies that benefit vulnerable patients.

An integrated transcriptomics and metabolomics study of the immune response of newly hatched chicks to the cytosine-phosphate-guanine oligonucleotide stimulation.

The immunological immaturity of the innate immune system during the first-week post-hatch enables pathogens to infect chickens, leading to the death of the animals. Current preventive solutions to improve the resistance of chicks to infections include vaccination, breeding, and sanitation. Other prophylactic solutions have been investigated, such as the stimulation of animal health with immunostimulants. Recent studies showed that administration of immune-modulators to one-day-old chicks, or in ovo, significantly reduces mortality in experimental bacterial or viral infection challenge models. Owing to a lack of molecular biomarkers required to evaluate chicken immune responses and assess the efficacy of vaccines or immune-modulators, challenge models are still used. One way to reduce challenge experiments is to define molecular signatures through omics approaches, resulting in new methodologies to rapidly screen candidate molecules or vaccines. This study aims at identifying a dual transcriptomics and metabolomics blood signature after administration of CpG-ODN (cytosine-phosphate-guanine oligodeoxynucleotides), a reference immune-stimulatory molecule. A clinical study was conducted with chicks and transcriptomics and metabolomics analyses were performed on whole-blood and plasma samples, respectively. Differentially expressed genes and metabolites with different abundance were identified in chicks treated with CpG-ODN. The results showed that CpG-ODN activated the innate immune system, within hours after administration, and its effect lasted over time, as metabolomics and transcriptomics profiles still varied 6 D after administration. In conclusion, through an integrated clinical omics approach, we deciphered in part the mode of action of CpG-ODN in post-hatch chicks.

CB1 receptor-mediated control of the release of endocannabinoids (as assessed by microdialysis coupled with LC/MS) in the rat hypothalamus.

In the present study, we examined the occurrence and potential regulation of endocannabinoid release by cannabinoid CB1 receptors in the rat brain. To this end, we developed a highly sensitive (limit of sensitivity 30-300 amol) new analytical method, combining online brain microdialysis with solid-phase extraction-liquid chromatography-tandem mass spectrometry, which allowed the detection in real time of trace amounts of endocannabinoids in the extracellular fluid. In the hypothalamus, anandamide and 2-arachidonoyl-glycerol release was stimulated following depolarization via local administration of K(+), with or without addition of Ca(2+), or glutamate application. Inhibition of fatty acid amide hydrolase by systemic administration of intraperitoneal (i.p.) URB597 (0.5 mg/kg) induced an increase of anandamide, but not 2-arachidonoyl-glycerol, outflow. The CB1 receptor antagonist rimonabant (10 mg/kg i.p.) increased, whereas the CB1 agonist WIN55,212-2 (2.5 mg/kg i.p.) decreased, anandamide release. Interestingly, the same treatments induced opposite changes in 2-arachidonoyl-glycerol release. At a dose of 3 mg/kg i.p., which by itself did not affect endocannabinoid release, rimonabant fully antagonized the effect of WIN55,212-2 (2.5 mg/kg i.p.). Taken together, these results suggest that CB1 receptors are able to control the local release of endocannabinoids in the hypothalamus via a feedback mechanism and strengthen the view that anandamide and 2-arachidonoyl-glycerol have distinct physiological roles.