“
“Pathogenicity of Chlamydia and Chlamydia-related bacteria could be partially mediated by an enhanced activation of the innate immune response. The study of this host pathogen interaction has proved challenging due to the restricted in vitro growth of these strict intracellular bacteria and the lack of genetic tools to manipulate their genomes. Despite these difficulties, the interactions of Chlamydiales with the innate immune cells and their effectors have been studied thoroughly. This review aims to point out the role of pattern recognition receptors and signal molecules (cytokines,

reactive oxygen species) of the innate immune response in the pathogenesis of chlamydial infection. Besides inducing clearance of the bacteria, some of these effectors may be used by the Chlamydia to establish chronic infections or to spread. Thus, the induced innate immune response seems to be variable Epacadostat order selleck kinase inhibitor depending on the species and/or the serovar, making the pattern more complex. It remains crucial to determine the common players of the innate immune response in order

to help define new treatment strategies and to develop effective vaccines. The excellent growth in phagocytic cells of some Chlamydia-related organisms such as Waddlia chondrophila supports their use as model organisms to study conserved features important for interactions between the innate immunity and Chlamydia. Due to their obligate intracellular nature, the detection and manipulation of Chlamydiales have proved challenging. Novel techniques such as real-time PCR facilitate the diagnosis of infections due to these pathogens. However, the absence of tools for genomic manipulation has limited the understanding of factors involved in host cell interactions. Several human diseases are known to be caused by members of the Chlamydiaceae family, but the pathogenic

role of more recently discovered species belonging to other families Thiamine-diphosphate kinase within the Chlamydiales order has yet to be investigated. Noteworthy, these distinct families (Parachlamydiaceae, Waddliaceae) each exhibit ≥10% 16S rRNA gene sequence divergence with the Chlamydiaceae, highlighting the significant genetic distance between Chlamydia-related bacteria and Chlamydia spp. (Greub, 2009). Such genetic divergence is in the order of magnitude of that present between Anaplasmataceae (Anaplasma, Ehrlichia) and Rickettsiaceae (Rickettsia) (Fournier et al., 2003). Many complications of chlamydial pathologies are thought to be entailed by an acute or sustained innate immune response to the Chlamydiales (reviewed for Chlamydia trachomatis in Ramsey, 2006). In addition to innate immunity, several components of the adaptive immunity have been implied in tissue damage. A recent review on C. trachomatis further elucidates the role of innate as well as adaptive immunity in damage to the uterine tube (Darville & Hiltke, 2010).