Induction of Type I and Type III Interferons by Borrelia burgdorferi Correlates with Pathogenesis and Requires Linear Plasmid 36

et al. (2014) Induction of Type I and Type III Interferons by Borrelia burgdorferi Correlates with Pathogenesis and Requires Linear Plasmid 36. PLoS ONE 9(6): e100174. doi:10.1371/journal.pone.0100174 Induction of Type I and Type III Interferons by Borrelia burgdorferi Correlates with Pathogenesis and Requires Linear Plasmid 36 Michelle A. Krupna-Gaylord 0 1 Dionysios Liveris 0 1 Andrea C. Love 0 1 Gary P. Wormser 0 1 Ira Schwartz 0 1 Mary M. Petzke 0 1 Brian Stevenson, University of Kentucky College of Medicine, United States of America 0 Current address: Division of Gastroenterology, Department of Medicine, The Icahn School of Medicine at Mount Sinai , New York, New York , United States of America 1 1 Department of Microbiology and Immunology, New York Medical College , Valhalla , New York, United States of America, 2 Division of Infectious Diseases, Department of Medicine, New York Medical College , Valhalla, New York , United States of America The capacity for Borrelia burgdorferi to cause disseminated infection in humans or mice is associated with the genotype of the infecting strain. The cytokine profiles elicited by B. burgdorferi clinical isolates of different genotype (ribosomal spacer type) groups were assessed in a human PBMC co-incubation model. RST1 isolates, which are more frequently associated with disseminated Lyme disease in humans and mice, induced significantly higher levels of IFN-a and IFN-l1/IL29 relative to RST3 isolates, which are less frequently associated with disseminated infection. No differences in the protein concentrations of IFN-c, IL-1b, IL-6, IL-8, IL-10 or TNF-a were observed between isolates of differing genotype. The ability of B. burgdorferi to induce type I and type III IFNs was completely dependent on the presence of linear plasmid (lp) 36. An lp36-deficient B. burgdorferi mutant adhered to, and was internalized by, PBMCs and specific dendritic cell (DC) subsets less efficiently than its isogenic B31 parent strain. The association defect with mDC1s and pDCs could be restored by complementation of the mutant with the complete lp36. The RST1 clinical isolates studied were found to contain a 2.5-kB region, located in the distal one-third of lp36, which was not present in any of the RST3 isolates tested. This divergent region of lp36 may encode one or more factors required for optimal spirochetal recognition and the production of type I and type III IFNs by human DCs, thus suggesting a potential role for DCs in the pathogenesis of B. burgdorferi infection. - Funding: This work was supported by a cooperative agreement (U01-CI000160) from the Centers for Disease Control and Prevention (to IS), The William and Sylvia Silberstein Foundation (to IS), ARRA supplement (3R01-AR41511) from the National Institutes of Health (to IS), and a predoctoral fellowship to MAK-G from the American Heart Association. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: Gary Wormser is the recipient of research grants from Immunetics, Inc.; BioRad; DiaSorin, Inc.; and BioMerieux. Dr. Wormser is a consultant for Baxter regarding Lyme disease vaccination. No competing interests exist for any other author. This does not alter the authors adherence to all PLoS ONE policies on sharing data and materials. Borrelia burgdorferi, a tick-transmitted spirochete, is the infectious agent of Lyme disease [1,2]. This disease is a multisystemic disorder with possible neurologic, rheumatologic, and cardiac symptoms which develop following hematogenous dissemination of the bacterium from the skin to distal target tissues [3]. The potential for Lyme disease to develop from the bite of an infected tick is highly variable due to the existence in nature of distinct B. burgdorferi genotypes with diverse capacities to cause infection or to disseminate. The genome of B. burgdorferi type strain B31-MI consists of a single linear chromosome and 21 linear and circular plasmids [4,5]. Linear plasmid 54 (lp54), circular plasmid 26 (cp26) and the chromosome are highly conserved and have been present in all tested natural isolates of B. burgdorferi. However, the presence and content of other plasmids vary among isolates [47]. A genotyping method for B. burgdorferi isolates based on restrictionfragment length polymorphism of the 16S23S ribosomal DNA spacer region has been developed [8,9]. A relationship between ribosomal spacer type (RST) and the capacity for disseminated infection was observed; RST1 strains are more frequently associated with disseminated infection in both Lyme disease patients and mice, whereas RST3 isolates are less frequently detected in the blood of patients and some do not disseminate in mice [1013]. The molecular mechanisms underlying the differential risk for hematogenous dissemination of different B. burgdorferi genotypes, however, have not been elucidated. B. burgdorferi induces the production of both pro- and antiinflammatory cytokines through the nuclear factor-kappa B (NFkB) signaling pathway [1418]. Internalization of intact B. burgdorferi and subsequent degradation and release of pathogen associated molecular patterns (PAMPs) within the phagolysosome are critical events leading to full activation of the innate immune response to this extracellular pathogen [16,17,1921]. Phagocytic uptake of intact spirochetes induces secretion of IFN-c by NK cells and triggers both apoptosis and the production of high levels of pro-inflammatory cytokines by human monocytes [16,17]. Recent findings have identified the endosomal receptors, TLR7 and TLR9 in dendritic cells, and TLR8 in monocytes, as pathogen recognition receptors (PRRs) essential for the production of type I IFN protein and the transcription of IFN-responsive genes by B. burgdorferi-stimulated human immune cells [2023]. Moreover, Cervantes et al. provided evidence using human monocytes that coordinated interactions between TLR8 and TLR2 facilitate the development of a diverse pro- and anti-inflammatory cytokine response by human monocytes [21]. However, despite the contribution of TLR2 to the initiation of B. burgdorferi-triggered signaling cascades both at the cell surface and within phagolysosomes, TLR2 is not required for spirochetal uptake [19]. Hawley et al. recently identified CR3 (CD11b) as a MyD88-independent phagocytic receptor for B. burgdorferi that also modulates TNF production by murine bone marrow-derived macrophages [24]. The B. burgdorferi ligand for CR3, as well as spirochetal components that mediate internalization by other phagocytic cell populations, remain unknown. Type I interferons (IFN-a/b), an innate defense classically associated with an antiviral immune state and produced at high levels by plasmacytoid dendritic cells (pDCs), are now known to be induced in response to a variety of intracellular and extracellular bacterial pathogens [20,2529]. Previously, using an ex vivo coincubat (...truncated)