Describe in detail how a hypothetical type-IV (4) secretion system might lead to IL-8 production by gastric epithelial cells.
Good question, this one encompasses both microbiology and cell biology. Type 4 secretion systems are a medically important class of structures on the surface of bacteria that can transfer virulence factors and genetic material into organisms from other kingdoms (including gastric epithelial cells). For this example I will use the human pathogen Bartonella henselae (Bh). One disease that Bh causes is Bacillary angiomatosis-peliosis which causes tumors through the colonization of human endothelial cells.
What happens when Bh starts injecting virulence proteins? ...
What happens when a bacterial type IV secretion system injects virulence proteins into a cell. The simple answer is that it unleashes a maelstrom of activity inside the cell including activation of transcription and gene expression.