Bordetella pertussismodulates human macrophage defense gene expression

Abstract

Bordetella pertussis, the etiological agent of whooping cough, still causes outbreaks. We recently found evidence that B. pertussis can survive and even replicate inside human macrophages, indicating that this host cell might serve as a niche for persistence. In this work, we examined the interaction of B. pertussis with a human monocyte cell line (THP-1) that differentiates into macrophages in culture in order to investigate the host cell response to the infection and the mechanisms that promote that intracellular survival. To that end, we investigated the expression profile of a selected number of genes involved in cellular bactericidal activity and the inflammatory response during the early and late phases of infection. The bactericidal and inflammatory response of infected macrophages was progressively downregulated, while the number of THP-1 cells heavily loaded with live bacteria increased over time postinfection. Two of the main toxins of B. pertussis, pertussis toxin (Ptx) and adenylate cyclase (CyaA), were found to be involved in manipulating the host cell response. Therefore, failure to express either toxin proved detrimental to the development of intracellular infections by those bacteria. Taken together, these results support the relevance of host defense gene manipulation to the outcome of the interaction between B. pertussis and macrophages.

Transcriptional profiling of human macrophages during infection withBordetella pertussis

“…For example, suppressors of cytokine signalling (SOCSs) proteins SOCS3 and SOCS2 belonging to important family of inflammatory response regulators [58] were shown to augment the infection with M. tuberculosis and S. enterica [59,60]. Highly induced expression of SOCS3 in infected macrophages is also in line with previous experiments, showing increased expression of SOCS3 gene in B. pertussisinfected THP-1 macrophages [21]. Similarly, increased expression of IDO1, LAMP3 and MARCKS genes in infected cells may correlate with attenuation of innate immune response and increased intracellular survival as it was shown for Mycobacterium leprae infection of monocytes [61], S. typhimurium infection of HeLa cells [62] and Burkholderia thailandensis infection of THP-1 macrophages and epithelial A549 cells [63], respectively.…”

“…Nevertheless, mouse is not a natural host of B. pertussis and in our study we were interested in specific interaction with human macrophages rather than with complex mouse immune system. To avoid donor-to-donor variation observed in experiments with primary macrophages, we used the THP-1 monocyte-derived cells, a popular cell model for immune modulations studies [37] which has also been shown to be a good surrogate for primary cells in experiments with B. pertussis [21]. Profiling of human respiratory epithelial cells [38] and THP-1 macrophages [21] following B. pertussis infection was studied using DNA microarrays and quantitative PCR, respectively, however, global RNA-seq analysis of transcriptional responses of human phagocytic cells to B. pertussis cells has not been performed as yet.…”

“…To avoid donor-to-donor variation observed in experiments with primary macrophages, we used the THP-1 monocyte-derived cells, a popular cell model for immune modulations studies [37] which has also been shown to be a good surrogate for primary cells in experiments with B. pertussis [21]. Profiling of human respiratory epithelial cells [38] and THP-1 macrophages [21] following B. pertussis infection was studied using DNA microarrays and quantitative PCR, respectively, however, global RNA-seq analysis of transcriptional responses of human phagocytic cells to B. pertussis cells has not been performed as yet. We have applied the dual RNA-seq approach allowing for analysis of transcriptomic profiles in both host and pathogen [39]; however, the major focus was set on the host side.…”

“…Collectively, these data led to speculations that B. pertussis could use macrophages as an intracellular niche and that the intramacrophage phase of infection could play a significant role in survival and persistence of bacteria within the host [12,17,18]. In support, gene expression profiling and proteomic analysis of infected monocyte-derived THP-1 macrophages revealed that intracellular B. pertussis cells modulate expression of several genes involved in response to the host immune system and reshape production of dozens of proteins implicated in virulence [20,21].…”

“…Within the last decade, Rodriguez and her team presented data indicating that B. pertussis can survive in primary macrophages [19]. They have shown that the majority of B. pertussis cells are killed within acidic compartments; however, some residual cells evade this killing and survive and replicate inside a non-acidic early endosome-like compartment [20,21]. Indeed, B. pertussis uses several mechanisms to avoid phagocytic killing.…”