Skip to main page content
Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
, 87 (1)

Yersinia pseudotuberculosis Exploits CD209 Receptors for Promoting Host Dissemination and Infection

Affiliations

Yersinia pseudotuberculosis Exploits CD209 Receptors for Promoting Host Dissemination and Infection

Ying-Xia He et al. Infect Immun.

Abstract

Yersinia pseudotuberculosis is a Gram-negative enteropathogen and causes gastrointestinal infections. It disseminates from gut to mesenteric lymph nodes (MLNs), spleen, and liver of infected humans and animals. Although the molecular mechanisms for dissemination and infection are unclear, many Gram-negative enteropathogens presumably invade the small intestine via Peyer's patches to initiate dissemination. In this study, we demonstrate that Y. pseudotuberculosis utilizes its lipopolysaccharide (LPS) core to interact with CD209 receptors, leading to invasion of human dendritic cells (DCs) and murine macrophages. These Y. pseudotuberculosis-CD209 interactions result in bacterial dissemination to MLNs, spleens, and livers of both wild-type and Peyer's patch-deficient mice. The blocking of the Y. pseudotuberculosis-CD209 interactions by expression of O-antigen and with oligosaccharides reduces infectivity. Based on the well-documented studies in which HIV-CD209 interaction leads to viral dissemination, we therefore propose an infection route for Y. pseudotuberculosis where this pathogen, after penetrating the intestinal mucosal membrane, hijacks the Y. pseudotuberculosis-CD209 interaction antigen-presenting cells to reach their target destinations, MLNs, spleens, and livers.

Keywords: CD209a; CD209b; DC-SIGN; DCs; LPS core; SIGN-R1; Yersinia pseudotuberculosis; dendritic cells; dissemination; lipopolysaccharide core.

Figures

FIG 1
FIG 1
Structures of inner core and outer core regions of the LPS or LOS of E. coli K-12, S. enterica serovar Typhimurium, Y. pestis, and Y. pseudotuberculosis and the genes involved in their biosynthesis. Genes involved in the biosynthesis of core LPS are shown at their approximate site of action (solid line). The sites that are variably substituted or still under investigation are indicated by dashed lines. Abbreviations: GlcNAc, N-acetylglucosamine; Glc, glucose; Hep, l-glycero-d-manno-heptose; Gal, galactose; P, phosphate; PPEtn, phosphoethanolamine; KDO, 2-keto-3-deoxyoctonate. It should be noted that E. coli K-12 and Y. pestis naturally do not possess an O-antigen.
FIG 2
FIG 2
Dissemination of Y. pseudotuberculosis in Peyer’s patch-deficient mice. Wild-type and lymphotoxin-LTβR-1-deleted mice (25) were orally infected with 108 CFU of Y. pseudotuberculosis YPIII (37). The dissemination rate (bacterial load) in the spleens, livers, and MLNs was quantified at 72 h after infection. *, P < 0.05.
FIG 3
FIG 3
Y. pseudotuberculosis cultured at 37°C but not 26°C invades human DCs and murine macrophages. Gentamicin protection- and flow cytometry-based assays were used to determine the DC invasion rates of Y. pseudotuberculosis Y1. E. coli K-12 strains (CS180 and CS1861) were utilized as controls. (A and C) Data from the gentamicin protection assay. (B and D) Data from flow cytometry. DCs and macrophages incubated with labeled and unlabeled bacteria are indicated by open and filled curves, respectively. Y. pseudotuberculosis organisms cultured at 37°C and 26°C are referred to as 37-Y1 and 26-Y1, respectively. ***, P < 0.001.
FIG 4
FIG 4
HeLa-hDC-SIGN and CHO-mSIGNR1 transfectants phagocytose Y. pseudotuberculosis grown at 37°C. The phagocytosis of two pairs of bacteria, E. coli K-12 (CS180 and CS1861) and Y. pseudotuberculosis Y1, cultured at 26°C and 37°C with HeLa/HeLa-hDC-SIGN (A) and CHO/CHO-mSIGNR1 (B), was performed by incubating cell lines for 2 h with indicated bacterial strains and by killing the extracellular bacteria with gentamicin as described in Materials and Methods. The number of phagocytosed bacteria was determined by counting CFU recovered following gentamicin treatment. ***, P < 0.001.
FIG 5
FIG 5
Human DCs and mouse macrophages phagocytose the defined rough Y. pseudotuberculosis. The phagocytosis of Y. pseudotuberculosis by human DCs (A) and mouse macrophages (B) followed the same procedures as those described in the legend to Fig. 3. The two strains used were the smooth LPS-producing Y. pseudotuberculosis PB1 and its isogenic rough derivative, the PB1Δwb strain, lacking the O-ag. (A and B) Data from the gentamicin protection assay. (C) Data from flow cytometry. DCs and macrophages with labeled and unlabeled bacteria are indicated by open and filled curves, respectively. ***, P < 0.001.
FIG 6
FIG 6
Human DC-SIGN and mouse SIGNR1 transfectants phagocytose the rough Y. pseudotuberculosis. The invasion of HeLa-hDC-SIGN (A) and CHO-mSIGNR1 (B) with PB1/PB1Δwb and PB1ΔailΔinv/PB1ΔwbΔailΔinv strains followed the same procedures as described for Fig. 4. ***, P < 0.001.
FIG 7
FIG 7
Phagocytosis of Y. pseudotuberculosis PB1ΔwbΔailΔinv strain by HeLa-DC-SIGN and CHO-mSIGN-R1 was blocked by anti-hDC-SIGN antibody, anti-mSIGN-R1 antibody, mannan, and LPS core. (A) Pretreated HeLa-NEO and HeLa-hDC-SIGN cells with anti-hDC-SIGN antibody, mannan, and LPS core were incubated for 2.5 h with the Y. pseudotuberculosis PB1ΔwbΔailΔinv strain. Bacterial phagocytosis was measured as described in Materials and Methods. (B) Pretreatment of cells with anti-mSIGN-R1 antibody, mannan, and LPS core blocked phagocytosis of the Y. pseudotuberculosis PB1ΔwbΔailΔinv strain to CHO-mSIGN-R1. P < 0.001.
FIG 8
FIG 8
Reduction of phagocytosis of Y. pseudotuberculosis PB1ΔwbΔailΔinv strain by DCs in the presence of anti-DC-SIGN, mannan, and LPS core together. Besides the addition of anti-hDC-SIGN, mannan, and LPS core, the procedures followed were the same as those described for DCs in the legend to Fig. 5A. P < 0.001 by two-way ANOVA comparing the interaction of DCs with Y. pseudotuberculosis PB1ΔwbΔailΔinv strain in the presence of anti-hDC-SIGN, mannan, and LPS core to the interaction in the absence of antibody.
FIG 9
FIG 9
Interaction of the LPS core with macrophages occurs in vivo. Bacterial suspensions of PB1Δwb and PB1 strains, cultured at 26°C, were inoculated into the intraperitoneal cavity of live mice. After incubation for 1.5 h, collected macrophages were examined for the rate of internalized bacteria. ***, P < 0.001.
FIG 10
FIG 10
Dissemination of Y. pseudotuberculosis was inhibited when covered with O-ag. Mice were infected orogastrically with 108 CFU of Y1/pBR322 or Y1/pAY100.1, and bacterial loads in the spleens, livers, and MLNs were quantified at 72 h postinfection. (A) For CFU counting, the homogenized samples of organs were spread on LB agar to recover the bacteria. Each circle represents the data obtained for one infected mouse, and horizontal boldface lines indicate the median values. *, P < 0.05. (B) Eight hours after inoculation in the real-time PCR assay, the absolute numbers of bacteria were determined from standard curves of serial dilutions of Y1 chromosome DNA. Values obtained from three independent measurements represent Y1/pAY100.1 DNA extracted from total tissue relative to that of Y1/pBR322. ***, P < 0.001. (C) After infection with Y1/pBR322-mCherry or Y1/pAY100.1-mCherry, mice were sacrificed and the spleens, livers, MLNs, and intestine were isolated for detection with the IVIS system, as shown in panel D. **, P < 0.005.
FIG 11
FIG 11
Blockage of the host-pathogen interaction with certain oligosaccharides reduces the infectivity by Y. pseudotuberculosis. After culture at 37°C, wild-type Y. pseudotuberculosis strain YPIII (37) bacteria with or without mannan or dextran were inoculated into mice by following procedures described in Materials and Methods. The rates of body weight loss (A) and mortality (B) were recorded every 12 h up to 156 h postinfection. Student's t test was used to determine significant differences in both body weight and death of mice by the wild-type Y. pseudotuberculosis YPIII with and without oligosaccharides, mannan, and dextran. *, P < 0.001.

Similar articles

See all similar articles

Cited by 3 PubMed Central articles

Publication types

MeSH terms

LinkOut - more resources

Feedback