Gene Expression Profiling of Immune System Cells Stimulated with Components of Lactobacillus acidophilus

Lactobacillus acidophilus (L. acidophilus) is one of major commensal bacteria in chicken intestine. Lactobacilli have been shown to exert health-promoting and immunostimulating activities. To examine the immunostimulating effects of probiotics, chicken cecal tonsil cells and splenocytes were stimulated in vitro with DNA, peptidoglycan, and cell envelope extracted from L. acidophilus. These bacterial constituents are known to stimulate innate defence mechanisms. Several gene clusters including chemokines and their receptors, antigen processing and presentations, apoptosis related genes were identified in the present study. These differentially expressed genes are candidates for detailed hypothesis-driven investigation of genes elucidating molecular/cellular mechanisms of effects of commensal bacteria on gut immune system in chickens. Keywords: Gene expression profiling of stimulated and unstimulated cells Cells were collected at 3, 6, and 12 hrs, and total RNA was isolated. A chicken immune microarray was used to study gene expression of stimulated cells compared to unstimulated controls. Four biological replicates for each treatment group in addition controls were labelled with either Cy5 or Cy3 with dye swap. Gene signal intensity was globally normalized by LOWESS and expressed on natural log scale. A mixed model including treatment, time, array, subgrid (random effect), dye, and all interactions among treatment, time was used to identify differentially expressed genes between treatments and control, at the 5% significance level.