The Campylobacter jejuniCiaD effector protein activates MAP kinase signaling pathways and is required for the development of disease

Abstract

BackgroundEnteric pathogens utilize a distinct set of proteins to modulate host cell signaling events that promote host cell invasion, induction of the inflammatory response, and intracellular survival. Human infection with Campylobacter jejuni, the causative agent of campylobacteriosis, is characterized by diarrhea containing blood and leukocytes. The clinical presentation of acute disease, which is consistent with cellular invasion, requires the delivery of the Campylobacter invasion antigens (Cia) to the cytosol of host cells via a flagellar Type III Secretion System (T3SS). We identified a novel T3SS effector protein, which we termed CiaD that is exported from the C. jejuni flagellum and delivered to the cytosol of host cells.ResultsWe show that the host cell kinases p38 and Erk 1/2 are activated by CiaD, resulting in the secretion of interleukin-8 (IL-8) from host cells. Additional experiments revealed that CiaD-mediated activation of p38 and Erk 1/2 are required for maximal invasion of host cells by C. jejuni. CiaD contributes to disease, as evidenced by infection of IL-10 knockout mice. Noteworthy is that CiaD contains a Mitogen-activated protein (MAP) kinase-docking site that is found within effector proteins produced by other enteric pathogens. These findings indicate that C. jejuni activates the MAP kinase signaling pathways Erk 1/2 and p38 to promote cellular invasion and the release of the IL-8 pro-inflammatory chemokine.ConclusionsThe identification of a novel T3SS effector protein from C. jejuni significantly expands the knowledge of virulence proteins associated with C. jejuni pathogenesis and provides greater insight into the mechanism utilized by C. jejuni to invade host cells.

A quantitative proteomic screen of the Campylobacter jejuni flagellar-dependent secretome

“…CJM1_0791 and CJM1_0395 were present only within M1 WT supernatants, confirming the data obtained by label-free LC/MS. Analysis of CysM was included for FLAG-tagging as it has previously been used as a marker for cell lysis [13]. Surprisingly CysM was readily detected within supernatant samples isolated from both M1 WT and flgG within the SILAC data.…”

“…Previous studies have identified multiple components of the C. jejuni flagellum that are required for the export of the Campylobacter invasion antigens (Cia), and other non-flagellar proteins, some of which have been implicated in the ability of C. jejuni to invade human intestinal cell lines [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16], [17]. CiaB was the first non-flagellar C. jejuni protein proposed to be dependent upon the flagellum for secretion, and is required for efficient invasion of INT-407 cells [9].…”

“…A ciaI mutant of C. jejuni F38011 displays reduced survival within INT-407 cells, while a ciaI mutant of C. jejuni 81–176 is reduced in its ability to colonize the chicken intestinal tract [11], [12]. Another Cia protein that is dependent on the flagellum for secretion, CiaD, is also required for maximal invasion of INT-407 cells [13], [14]. Furthermore, FlaC and FspA also require a minimum flagellar structure for extracellular secretion [15], [16].…”

The Intestinal Microbiota Influences Campylobacter jejuni Colonization and Extraintestinal Dissemination in Mice

“…This mutant should be attenuated in mice as C. jejuni utilizes the flagellum for both motility and secretion of virulence proteins that are delivered to host epithelial cells (29,30).…”

The Shigella flexneri OspB effector: an early immunomodulator

“…It has been shown that MKD motifs direct individual kinases toward the correct substrates (Bardwell, 2006). MDK motifs are present in severeal MAPK substrates, activators and regulators such as bacterial effector proteins (SpvC, OspF, VP1680 and CiaD from Salmonella enterica, S. flexneri, Vibrio parahaemolyticus and Campylobacter jejuni, respectively) (Zhu et al, 2007;MatlawskaWasowska et al, 2010;Samuelson et al, 2013). Furthermore, new work is needed to unravel the role, if any, of MDK and ((S/T)P) motifs of OspB in the activation of ERK1/2 and p38 MAPKs.…”