The loss and gain of marginal zone and peritoneal B cells is different in response to relapsing fever and Lyme disease Borrelia.

T cell-independent Abs are protective against Lyme disease and relapsing fever, illnesses caused by Borrelia spirochetes with distinct blood-borne phases of infection. To understand this protective response, we characterized splenic and peritoneal B cell compartments during infection using flow cytometry and immunohistochemistry. In the spleen, early after infection, Borrelia crocidurae, a relapsing fever species, induced a striking loss of marginal zone (MZ) B cells from the MZ, while Borrelia burgdorferi, the agent of Lyme disease, induced the expansion of this subset. At the same time, no significant changes were observed in follicular B cells in response to either species of Borrelia. In the peritoneal cavity, a further loss was demonstrated early in response to B. crocidurae in the B1b, B1c, and B2 cell subsets, but B1a cells were not significantly altered. The loss of B1c and B2 cells was sustained through subsequent peaks of spirochetemia, suggesting these subsets may be important in resolving relapsing episodes. In contrast, an early and significant increase in peritoneal B1a, B1b, and B1c cells, but not B2 cells, occurred in response to B. burgdorferi. Later in the course of infection, both species of Borrelia induced the selective expansion of peritoneal B1b cells, suggesting that B1b cells may participate in long-lasting immunity to Lyme and relapsing fever spirochetes. Our data demonstrate that different Borrelia can activate the same B cell subsets in distinct ways and they each elicit a complex interplay of MZ and multiple peritoneal B cell subsets in the early response to infection.

Murine microglia are effective phagocytes for Borrelia burgdorferi.

Lyme disease is a multi-systemic infection that causes diverse neurologic dysfunction collectively known as neuroborreliosis. In the murine model of Lyme disease, Borrelia burgdorferi are seldom found in the nervous system indicating that the spirochetes are rapidly cleared from the brain and peripheral nerves. In the present study, we examined the interaction between microglia and B. burgdorferi. Murine microglia are efficient phagocytes and are capable of ingesting and killing spirochetes with or without opsonization.

The fur homologue in Borrelia burgdorferi.

Borrelia burgdorferi contains a gene that codes for a Fur homologue. The function of this Fur protein is unknown; however, spirochetes grown at 23 or 35 degrees C expressed fur as determined by reverse transcriptase PCR. The fur gene (BB0647) was cloned and overexpressed as a His-Fur fusion protein in Escherichia coli. The fusion protein was purified by zinc-chelate chromatography, and the N-terminal His tag was removed to generate recombinant Fur for use in mobility shift studies. Fur bound DNA containing the E. coli Fur box sequence (GATAATGATAATCATTATC) or Bacillus subtilis Per box sequence (TTATAAT-ATTATAA) with an apparent Kd of approximately 20 nM. Fur also bound the upstream sequences of three Borrelia genes: BB0646 (gene encoding a hydrolase of the alpha/beta-fold family), BB0647 (fur), and BB0690 (napA). Addition of metal ions was not required. Binding activity was greatly decreased by either exposure to oxidizing agents (H2O2, t-butyl hydroperoxide, cumene hydroperoxide, or diamide) or by addition of Zn2+. B. burgdorferi NapA is a homologue of Dps. Dps functions in E. coli to protect DNA against damage during periods of redox stress. Fur may function in B. burgdorferi as a repressor and regulate oxidative stress genes. Additional genes (10 chromosomal and 15 plasmid) that may be Fur regulated were identified by in silico analysis.

Whole-genome DNA array analysis of the response of Borrelia burgdorferi to a bactericidal monoclonal antibody.

Identification and characterization of genes that contribute to infection with Borrelia burgdorferi and, of those, genes that are targets of host responses is important for understanding the pathogenesis of Lyme disease. The complement-independent bactericidal monoclonal antibody (MAb) CB2 recognizes a carboxy-terminal, hydrophilic epitope of the outer surface protein B (OspB). CB2 kills B. burgdorferi by an unknown bactericidal mechanism. Upon binding of CB2 to OspB, differentially expressed gene products may be responsible for, or associated with, the death of the organism. A time course of the response of B. burgdorferi to CB2 was completed to analyze the differential gene expression in the bacteria over a period of visual morphological changes. Bacteria were treated with a sublethal concentration in which spirochetes were visibly distressed by the antibody but not lysed. Preliminary whole-genome DNA arrays at various time points within 1 h of incubation of B. burgdorferi with the antibody showed that most significant changes occurred at 25 min. Circular plasmid 32 (cp32)-encoded genes were active in this period of time, including the blyA homologs, phage holin system genes. DNA array data show that three blyA homologs were upregulated significantly, >/==" BORDER="0">2 standard deviations from the mean of the log ratios, and a P value of

Astrocytic ceruloplasmin expression, which is induced by IL-1beta and by traumatic brain injury, increases in the absence of the IL-1 type 1 receptor.

IL-1alpha and IL-1beta are induced immediately after insults to the brain, and signaling through the type 1 IL-1 receptor is essential for a normal microglial and astroglial response to injury. To better understand which genes are induced in astrocytes by IL-1beta, we used the unbiased technique of differential display to analyze mouse astroglial gene expression after IL-1beta treatment. Two novel genes were induced, as well as the gene for ceruloplasmin, a ferroxidase with antioxidant properties. Ceruloplasmin was analyzed further by Northern and Western blot. RNA and protein levels of ceruloplasmin were increased when astrocytes were treated with IL-1beta. To determine whether the IL-1 type 1 receptor (IL-1R1) is essential for the injury-induced expression of ceruloplasmin, a Western blot analysis was performed after a traumatic brain injury on mice that were IL-1R1-deficient. Ceruloplasmin increased significantly above controls after injury; however, injury-induced levels of ceruloplasmin were lower in IL-1R1-deficient (2.7-fold increase) than in the wild-type animals (3.5-fold increase). These data indicate that while IL-1R1 deletion has a slight effect on ceruloplasmin expression, it is not essential for either the basal or the induced expression of ceruloplasmin in vivo. Since ceruloplasmin buffers free copper, oxidizes ferrous iron, and catalyzes the dismutation of free radicals, increased levels of ceruloplasmin likely protect neurons and glia from sustaining damage after injury. Furthermore, as the IL-1R1 has been proposed to be a target for achieving neuroprotection after injury, these data suggest that the protection afforded by ceruloplasmin will be retained even when the IL-1R1 is antagonized.