Search

In Lyme borreliosis, the skin is the key site for bacterial inoculation by the infected tick and for cutaneous manifestations. We previously showed that different strains of Borrelia burgdorferi sensu stricto isolated from tick and from different clinical stages of the Lyme borreliosis (erythema migrans, and acrodermatitis chronica atrophicans) elicited a very similar transcriptional response in normal human dermal fibroblasts. In this study, using whole transcriptome microarray chips, we aimed to compare the transcriptional response of normal human dermal fibroblasts stimulated by 3 Borrelia burgdorferi sensu lato strains belonging to 3 main pathogenic species (B. afzelii, B. garinii and B. burgdorferi sensu stricto) in order to determine whether "species-related" inflammatory pathways could be identified. The three Borrelia strains tested exhibited similar transcriptional profiles, and no species-specific fingerprint of transcriptional changes in fibroblasts was observed. Conversely, a common core of chemokines/cytokines (CCL2, CXCL1, CXCL2, CXCL6, CXCL10, IL-6, IL-8) and interferon-related genes was stimulated by all the 3 strains. Dermal fibroblasts appear to play a key role in the cutaneous infection with Borrelia, inducing a homogeneous inflammatory response, whichever Borrelia species was involved., Competing Interests: The authors have declared that no competing interests exist.

The skin plays a key role in vector-borne diseases because it is the site where the arthropod coinoculates pathogens and its saliva. Lyme borreliosis, particularly well investigated in this context, is a multisystemic infectious disease caused by Borrelia burgdorferi sensu lato and transmitted by the hard tick Ixodes. Numerous in vitro studies were conducted to better understand the role of specific skin cells and tick saliva in host defense, vector feeding, and pathogen transmission. The skin was also evidenced in various animal models as the site of bacterial multiplication and persistence. We present the achievements in this field as well as the gaps that impede comprehensive knowledge of the disease pathophysiology and the development of efficient diagnostic tools and vaccines in humans. The skin is a key interface in vector-borne diseases, such as malaria, trypanosomiasis, leishmaniasis, and dengue fever, as a site of pathogen and vector saliva inoculation. The saliva of the Ixodes ticks plays a major role in the modulation of the pharmacology (coagulation, pain, and itching) and the immunology of the vertebrate host. Tick saliva is, together with that of the sandfly, among the best studied in arthropods. The skin is an important site of multiplication and persistence of Borrelia , the extracellular bacterium responsible for Lyme borreliosis. The persistence occurs in the absence of skin inflammation, which highlights the immunotolerance of the host skin to the bacteria. Investigation of the skin as an immunotolerant organ should be intensified to favor the identification of new vaccine candidates and to develop innovative diagnostic techniques such as proteomics. [ABSTRACT FROM AUTHOR]

Ticks are vectors of infectious diseases of major importance in human and veterinary medicine. For epidemiological studies, accurate identification of ticks is crucial to define their potential role as vectors and to develop control and prevention strategies. Although morphological and molecular methods are widely used to identify ticks, an innovative approach using MALDI-TOF MS technology recently emerged as an alternative tool. Previous works showed that MALDI-TOF MS was highly effective in identifying ticks, but these works mainly tested tick specimens of different genera. To confirm the accuracy of this new tool for tick identification, nine closely related tick species belonging to the Ixodes genus were analysed, specimens of the Dermacentor reticulatus species were also included in the analysis as an outer group. Three of the species used for the present study belonged to the I. ricinus species complex, which are known to transmit Borrelia burgdorferi sensu lato, the causative agent of Lyme borreliosis. A total of 246 tick specimens were submitted to MALDI-TOF MS analysis, and two body parts (half-idiosoma and four legs) were individually investigated. For each body part, intraspecies reproducibility and interspecies specificity of the MS profiles were determined. The profile analysis revealed that the main determinant for spectra clustering was the tick species for both legs and half-idiosoma. For each body part, a reference database of spectra was set up including 2 to 5 specimens per species randomly selected, and genotyped using 16s rDNA and COI genes to confirm their morphological identification. Both created spectral databases were individually blind tested with their respective body part using the remaining specimens, which were correctly identified in 98.5% of the cases. MALDI-TOF MS is a reliable tool for tick identification, including specimens belonging to closely related species and hardly distinguishable using morphology. The 4-legs as well as the half-idiosoma of ticks can now be applied for specimen identification using two different databases. The combined use of these two body parts improves the rate of tick identification and their confidence level. [ABSTRACT FROM AUTHOR]

Résumé: La borréliose de Lyme est une spirochétose transmise par piqûre de tique. La manifestation clinique la plus fréquente est l’érythème migrant. Le pathogène peut disséminer par voie hématogène vers différents tissus et organes, incluant principalement le système nerveux, les articulations, et la peau. Les tests biologiques, principalement basés sur la sérologie, sont essentiels au diagnostic de la maladie, à l’exception de l’érythème migrant dont le diagnostic doit rester strictement clinique. Le traitement est basé sur l’utilisation d’une des 3 classes d’antibiotiques suivante : β-lactamines, cyclines ou macrolides, pour une durée de 2 à 4 semaines en fonction du contexte clinique. Outre la protection contre les piqûres de tiques, la mesure de prévention individuelle la plus efficace repose, en cas d’exposition, sur le dépistage et le retrait précoces des tiques fixées à la peau. [Copyright &y& Elsevier]