Global Transcriptome Analysis of Staphylococcus aureus Biofilms in Response to Innate Immune Cells

Abstract

bThe potent phagocytic and microbicidal activities of neutrophils and macrophages are among the first lines of defense against bacterial infections. Yet Staphylococcus aureus is often resistant to innate immune defense mechanisms, especially when organized as a biofilm. To investigate how S. aureus biofilms respond to macrophages and neutrophils, gene expression patterns were profiled using Affymetrix microarrays. The addition of macrophages to S. aureus static biofilms led to a global suppression of the biofilm transcriptome with a wide variety of genes downregulated. Notably, genes involved in metabolism, cell wall synthesis/structure, and transcription/translation/replication were among the most highly downregulated, which was most dramatic at 1 h compared to 24 h following macrophage addition to biofilms. Unexpectedly, few genes were enhanced in biofilms after macrophage challenge. Unlike coculture with macrophages, coculture of S. aureus static biofilms with neutrophils did not greatly influence the biofilm transcriptome. Collectively, these experiments demonstrate that S. aureus biofilms differentially modify their gene expression patterns depending on the leukocyte subset encountered.

Critical review on biofilm methods

“…In such experiment, the bias of bacterial metabolism would be removed and the omics data obtained would provide insights into how the biofilm reacted to a certain stimuli. Such approach has been used in the medical fields, to better assess how intact biofilms survive to external stimuli (Franca et al, 2014;Scherr et al, 2013). Of course, physiological investigations comparing a wild type strain with an isogenic mutant remain the best and less dubious experimental approach but this is not always applicable when investigating the effect of different environmental conditions on cell physiology.…”

Dynamics of the Streptococcus gordonii Transcriptome in Response to Medium, Salivary α-Amylase, and Starch

“…It has now been widely used for the global transcriptome analysis of many microorganisms (17)(18)(19). Thus, the goals of the present study …”

“…It has now been widely used for the global transcriptome analysis of many microorganisms (17)(18)(19). Thus, the goals of the present study were to use RNA-Seq to (i) determine the effect of abpA deletion on gene expression of S. gordonii when grown in different media, (ii) determine the transcriptional changes of S. gordonii after binding to human salivary amylase in different growth media, and (iii) determine the effect of amylase and starch on the transcriptional changes in S. gordonii.…”

Anti-inflammatory effect of thalidomide dithiocarbamate and dithioate analogs

“…In 325 contrast, thalidomide has been enhancing T cells proliferation and 326 slightly increases CD8+ to CD4+ T cells level [27][28][29][30][31][32]. 327 MQ are the first line of defense in innate immunity against 328 microbial infection [33]. Professional phagocytes engulf and kill Table 2 The scavenging capacity of thalidomide and thalidomide analogs (20 lM) was detected fluorometrically against ROO Å and OH Å radicals in comparison to the Trolox capacity, using AAPH and CuSO 4 -H 2 O 2 radical generators, respectively.…”

“…MTT assay was used to assess the 32 cytotoxic effect of thalidomide analogs against splenocytes. Tumor necrosis factor (TNF-a) and nuclear 33 factor kappa B (NF-jB-P65) were determined by enzyme-linked immunosorbent assay (ELISA). Nitric 34 oxide (NO) was estimated by colorimetric assay.…”