Campylobacter jejuni induces autoimmune peripheral neuropathy via Siglec-1 and IL-4 axes (MUC5P.746)

Campylobacter jejuni is the most common bacterial cause of gastroenteritis worldwide. C. jejuni infection has also been causally linked with development of the peripheral neuropathy called Guillain Barré Syndrome (GBS). We have previously shown that C. jejuni isolates from human enteritis patients induce a Type1/17 cytokine dependent colitis response in IL-10-/- mice. In contrast, isolates from human GBS patients colonize the IL-10-/- mice without inducing colitis but instead induce autoantibody elicitation targeted against peripheral nerve antigens. We show here that the autoantibody response is dependent upon blunted Type1/17 but enhanced Type2 cytokine production by T helper cells. Autoantibody elicitation also correlated with enhanced macrophage infiltration in the sciatic nerve and its dorsal root ganglia. Autoantibodies and these histological changes were significantly decreased in mice depleted of IL-4, without leading to colitis induction. Histological damage in the sciatic nerve was associated with abnormal gait and hind limb movements in the IL-10-/- mice, consistent with this syndrome’s manifestation in humans. Furthermore, we show here that Siglec1 is a central antigen presenting cell receptor that mediates GBS but not colitogenic isolate uptake, T cell differentiation and autoantibody elicitation. Therefore, this is the first mouse model of an autoimmune disease induced directly by a bacterium and it is dependent upon Siglec1 and IL-4 axes.

The Campylobacter jejuni CiaD effector protein activates MAP kinase signaling pathways and is required for the development of disease

Background

Enteric pathogens utilize a distinct set of proteins to modulate host cell signaling events that promote host cell invasion, induction of the inflammatory response, and intracellular survival. Human infection with Campylobacter jejuni, the causative agent of campylobacteriosis, is characterized by diarrhea containing blood and leukocytes. The clinical presentation of acute disease, which is consistent with cellular invasion, requires the delivery of the Campylobacter invasion antigens (Cia) to the cytosol of host cells via a flagellar Type III Secretion System (T3SS). We identified a novel T3SS effector protein, which we termed CiaD that is exported from the C. jejuni flagellum and delivered to the cytosol of host cells.

Results

We show that the host cell kinases p38 and Erk 1/2 are activated by CiaD, resulting in the secretion of interleukin-8 (IL-8) from host cells. Additional experiments revealed that CiaD-mediated activation of p38 and Erk 1/2 are required for maximal invasion of host cells by C. jejuni. CiaD contributes to disease, as evidenced by infection of IL-10 knockout mice. Noteworthy is that CiaD contains a Mitogen-activated protein (MAP) kinase-docking site that is found within effector proteins produced by other enteric pathogens. These findings indicate that C. jejuni activates the MAP kinase signaling pathways Erk 1/2 and p38 to promote cellular invasion and the release of the IL-8 pro-inflammatory chemokine.

Conclusions

The identification of a novel T3SS effector protein from C. jejuni significantly expands the knowledge of virulence proteins associated with C. jejuni pathogenesis and provides greater insight into the mechanism utilized by C. jejuni to invade host cells.

Passage of Campylobacter jejuni through the chicken reservoir or mice promotes phase variation in contingency genes Cj0045 and Cj0170 that strongly associates with colonization and disease in a mouse model

Human illness due to Camplyobacter jejuni infection is closely associated with consumption of poultry products. We previously demonstrated a 50 % shift in allele frequency (phase variation) in contingency gene Cj1139 (wlaN) during passage of C. jejuni NCTC11168 populations through Ross 308 broiler chickens. We hypothesized that phase variation in contingency genes during chicken passage could promote subsequent colonization and disease in humans. To test this hypothesis, we passaged C. jejuni strains NCTC11168, 33292, 81-176, KanR4 and CamR2 through broiler chickens and analysed the ability of passaged and non-passaged populations to colonize C57BL6 IL-10-deficient mice, our model for human colonization and disease. We utilized fragment analysis and nucleotide sequence analysis to measure phase variation in contingency genes. Passage through the chicken reservoir promoted phase variation in five specific contingency genes, and these 'successful' populations colonized mice. When phase variation did not occur in these same five contingency genes during chicken passage, these 'unsuccessful' populations failed to colonize mice. Phase variation during chicken passage generated small insertions or deletions (indels) in the homopolymeric tract (HT) in contingency genes. Single-colony isolates of C. jejuni strain KanR4 carrying an allele of contingency gene Cj0170 with a10G HT colonized mice at high frequency and caused disease symptoms, whereas single-colony isolates carrying the 9G allele failed to colonize mice. Supporting results were observed for the successful 9G allele of Cj0045 in strain 33292. These data suggest that phase variation in Cj0170 and Cj0045 is strongly associated with mouse colonization and disease, and that the chicken reservoir can play an active role in natural selection, phase variation and disease.

Development, operation, and long-term performance of a full-scale biocurtain utilizing bioaugmentation

A full-scale field evaluation of bioaugmentation was conducted in a carbon tetrachloride (CT)- and nitrate-impacted aquifer at Schoolcraft, MI. The added organism was Pseudomonas stutzeri KC (strain KC), a denitrifying bacterium that cometabolically degrades CT without producing chloroform (CF). To introduce and maintain strain KC in the aquifer, a row of closely spaced (1-m) injection/extraction wells were installed normal to the direction of groundwater flow near the leading edge of the CT plume. The resulting system of wells was used to establish and maintain a "biocurtain" for CT degradation through the intermittent addition of base to create favorable pH conditions; inoculation; and weekly addition of acetate (electron donor), alkali, and phosphorus. Although half of the test zone was inoculated twice, the long-term performance of both sections was indistinguishable: both had high CT removal efficiencies (median of 98-99.9%) and similar levels of strain KC colonization (>10(5) strain KC/g). Sustained and efficient (98%) removal of CT has now been observed over 4 yr. Transient low levels of CF (<20 ppb) and H2S (<2 ppm) were observed, but both disappeared when the concentration of acetate in the weekly feed was reduced. Nitrate removal efficiencies ranged from 60% at low acetate concentrations to nearly 100% at high acetate concentrations. We conclude that closely spaced wells and intermittent substrate addition are effective means of delivering organisms and substrates to subsurface environments. At the Schoolcraft site, we achieved uniform removal efficiencies over a significant vertical depth (15 m), despite significant variability in hydraulic conductivity. This was accomplished by pumping 65% (v/v) of the natural gradient flow passing through the biocurtain during a given week in a single 6-h pumping event. Approximately 18,600 m3 of contaminated groundwater was treated during the project.

Light quality effects on corn chloroplast development

Corn was grown under greenhouse and controlled light quality conditions incluing full spectrum, red (R), and far-red (FR) sources. Young leaf samples were analyzed for pigments, pigment-proteins, membrane polypeptides, and ultrastructure. Chloroplast development in full spectrum white light was similar to that found in R but different from that found in FR plus low R. Compared to greenhouse and R, FR plus low R (670-760) repressed the formation of photosystem I reaction center protein (CP1 + CP1a) and enhanced those of photosystem II (CPa) in both bundle sheath and mesophyll cells. Photosystem II polypeptides were present in both cell types, with the 46 and 34 kilodalton proteins predominant in mesophyll cells. Bundle sheath cells contained relatively more of the 51 kilodalton and less of the 46 kilodalton proteins. However, they also contained measurable amounts of ribulose bisphosphate carboxylase which may interfere with estimates of the 51 kilodalton protein.

Phagocyte dysfunction in common variable immune deficiency

The history of a 13-year old boy is reported who suffered from frequent bacterial, enteroviral, and protozoal infections since late infancy. A decrease in the serum levels of IgG2, IgG3, IgA, a neutrophil dysfunction, and a partial cellular immune deficiency could be demonstrated. A deficiency of folic acid produced a pancytopenia which enhanced the patient's susceptibility to infections. The combined substitution of gammaglobulins and folic acid only was able to break this vicious cycle.

A light and electron microscopic study of the ciliated urn of Phasolosoma agassizii (Sipunculida)

The free swimming ciliated urn found in the coelomic fluid of Phascolosoma agassizii has been studied by electron microscopy. The urn is a multicellular structure composed of three cell types: (a) ciliated cells which possibly function in capturing cell debris and foreign particles; (b) cupola cells which are capable of phagocytozing latex particles; and (c) lobe cells which are capable of phagocytozing carbon particles. The lobes are separated from the ciliated cells by a semilunar area, with mucoprotein staining characteristics, containing fibrils which appear to be the structural support for the urn. Ciliated cells and lobes are attached to the semilunar area by hemidesmosomes.

Defects in granulocyte function in various chromosome abnormalities (Down's-, Edwards'-, Cri-du-chat syndrome)

In five infants with autosomal aberrations and diminished resistance to infection (in spite of intact humoral and cellular immune mechanisms) several granulocyte functions (chemotaxis, phagocytosis, intracellular killing and metabolism of killing) were measured. A serum-dependent or a cell-dependent disturbance of phagocytosis of Candida albicans was found in two infants with cat-cry syndrome and one with trisomy 18. In one of these children there was an additional serum dependent defect of the killing of Candida albicans and of Staphylococcus aureus, serum levels of opsonins (IgG, IgM, CH50 and C3) being within normal range. An infant with trisomy 21 showed, in addition to a cellular defect of chemotaxis, a reduced cellular ability of the killing of Staphylococcus aureus and of Escherichia coli in autologous and AB-pool-serum. Phagocytosis of these bacteria remained normal.

[Experimental candida keratitis. Histological, immunological and electron microscopical studies (author's transl)]

Using histological, immunohistological and electron microscopical methods, it could be demonstrated that the course of experimental Candida albicans keratitis in mice invlves three phases: a traumatically caused alternative phase is followed by a granulocytic exsudative phase and finally by a proliferative phase. The experiments were followed over 41 days. Fungal elements could be detected only during the first 4 days after infection. When topically treated with hydrocortisone, the exsudation of leucocytes was diminished and delayed and the cellular proliferation was reduced considerably in the challenged corneal stroma. A lower number of Candida organisms was found in the cornea when treatment with hydrocortisone was combined with the antifungal drug pimaricin. When treated with pimaricin only however, fungal growth and inflammation were least apparent.