Gut Microbiome Profiles in CB2R-Knockout and Wild-Type Mice With and Without Salmonella Infection
Description
This dataset examines how genetic deletion of cannabinoid receptor 2 (CB2R) impacts gut microbiome composition during Salmonella enterica serovar Typhimurium infection. CB2R is a G protein-coupled receptor involved in regulating immune responses and intestinal homeostasis. Its expression in immune cells and the gastrointestinal tract suggests a potential role in shaping host-microbiota interactions. To investigate whether CB2R deficiency alters microbial dynamics in a way that influences susceptibility to infection, we compared CB2R knockout (CB2R-KO) mice with wild-type (WT) littermate controls in an oral Salmonella challenge model. Fecal samples were collected at two time points: pre-infection (baseline) and four days post-infection. Samples were subjected to shallow shotgun metagenomic sequencing (1×150 bp, Illumina). Raw reads were filtered using Vsearch to remove low-quality sequences and short fragments. Taxonomic classification was performed with Kraken2, and processed data were analyzed using R (phyloseq, ALDEx2, microbiome packages). Alpha diversity analysis showed no significant difference in species richness or evenness between genotypes. However, CB2R-KO mice exhibited distinct shifts in microbial composition following infection. These findings suggest that CB2R contributes to maintaining a balanced gut microbial ecosystem and that its absence may promote dysbiosis during enteric infection, potentially increasing host susceptibility.
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Steps to reproduce
CB1 receptor knockout (CB1R-KO) and CB2 receptor knockout (CB2R-KO) mice, on a C57BL/6 background, were bred and housed under specific pathogen-free (SPF) conditions at the University of Florida. Mice were maintained in individually ventilated cages with controlled environmental conditions and ad libitum access to autoclaved food and water. All procedures were approved by the Institutional Animal Care and Use Committee (IACUC). To assess the impact of cannabinoid receptor deficiency on microbiome dynamics during infection, 8–12-week-old male and female CB1R-KO, CB2R-KO, and wild-type (WT) littermate controls were orally infected with Salmonella enterica serovar Typhimurium (strain SL1344). Mice received 7.5 × 10⁷ CFU of bacteria in 50 µL of sterile PBS via oral gavage. Control animals received PBS alone. Infections were performed using sterile technique to prevent cross-contamination and preserve microbial integrity. Fecal samples were collected from each mouse at baseline (pre-infection) and four days post-infection. Fresh pellets were collected using sterile tools and transferred into DNA stabilization tubes (Transnetyx). Samples were stored at 4°C and shipped under cold-chain conditions for processing within 24 hours. Microbiome profiling was conducted via shallow shotgun whole-genome sequencing (1×150 bp, Illumina). Raw sequencing reads were quality-filtered using Vsearch to remove sequences with expected error >0.5 and fragments <150 bp. High-quality reads were taxonomically classified using Kraken2 with the standard database. The resulting data were imported into R and formatted into phyloseq objects for analysis. Sequencing libraries were rarefied to a minimum depth of 1,609,000 reads per sample to standardize comparisons. Alpha diversity metrics (e.g., Shannon index) were calculated using the microbiome R package and visualized with ggplot2. Group-level differences in diversity were tested using the Kruskal-Wallis test. Differential abundance analysis was performed using the ALDEx2 package, which applies a Bayesian approach for compositional data.
Institutions
- University of FloridaFL, Gainesville