Lampron et al. use a cuprizone mouse model of demyelination/remyelination to show that in CX3CR1-deficient mice, the clearance of myelin debris by microglia is impaired, affecting the integrity of axon and myelin sheaths.

Streptococcus suis, an important swine and human pathogen, causes septic shock and meningitis. The pathogenesis of both systemic and CNS infections caused by S. suis is poorly understood. A hematogenous model of infection in CD1 mice was developed to study the systemic release of cytokines during the septic shock phase and the proinflammatory events in the CNS associated with this pathogen. Using a liquid array system, high levels of systemic TNF-α, IL-6, IL-12, IFN-γ, CCL2, CXCL1, and CCL5 were observed 24 h after infection and might be responsible for the sudden death of 20% of animals. Infected mice that survived the early sepsis later developed clinical signs of meningitis and exhibited lesions in the meninges and in numerous regions of the brain, such as the cortex, hippocampus, thalamus, hypothalamus, and corpus callosum. Bacterial Ags were found in association with microglia residing only in the affected zones. In situ hybridization combined with immunocytochemistry showed transcriptional activation of TLR2 and TLR3 as well as CD14, NF-κB, IL-1β, CCL2, and TNF-α, mainly in myeloid cells located in affected cerebral structures. Early transcriptional activation of TLR2, CD14, and inflammatory cytokines in the choroid plexus and cells lining the brain endothelium suggests that these structures are potential entry sites for the bacteria into the CNS. Our data indicate an important role of the inflammatory response in the pathogenesis of S. suis infection in mice. This experimental model may be useful for studying the mechanisms underlying sepsis and meningitis during bacterial infection.

We completed a genome-wide scan for susceptibility loci for bipolar affective disorders in families derived from a rather homogeneous population in the Province of Québec. The genetic homogeneity of this population stems from the migration of founding families into this relatively isolated area of Québec in the 1830s. A possible founder effect, combined with a prevalence of very large families, makes this population ideal for linkage studies. Genealogies for probands can be readily constructed from a population database of acts of baptism and marriage from the early 1830s up to the present time (the BALSAC register). We chose probands with a DSM III diagnosis of bipolar affective disorder and who may be grouped within large families having genealogical origins with the founding population of the Saguenay-Lac-St-Jean area. Living members (n approximately 120) of a very large pedigree were interviewed using the Structured Clinical Interview for DSM III (SCID I), SCID II, and with a family history questionnaire. A diagnostic panel evaluated multisource information (interview, medical records, family history) and pronounced best-estimate consensus diagnoses on all family members. Linkage, SimAPM, SimIBD, and sib-pair analyses have been performed with 332 microsatellite probes covering the entire genome at an average spacing of 11 cM. GENEHUNTER and haplotype analyses were performed on regions of interest. Analysis of a second large pedigree in the same regions of interest permitted confirmation of presumed linkages found in the region of chromosome 12q23-q24.

SUMMARY IL-1 has multiple functions in both the periphery and the central nervous system (CNS) and is regulated at many levels. We identified a novel isoform of the IL-1R Accessory Protein (termed AcPb) that is expressed exclusively in the CNS. AcPb interacted with IL-1 and the IL-1 receptor but was unable to mediate canonical IL-1 responses. AcPb expression, however, modulated neuronal gene expression in response to IL-1 treatment in vitro. Animals lacking AcPb demonstrated an intact peripheral IL-1 response and developed experimental autoimmune encephalomyelitis (EAE) similarly to wild type mice. AcPb-deficient mice were instead more vulnerable to local inflammatory challenge in the CNS and suffered enhanced neuronal degeneration as compared to AcP-deficient or wild type mice. These findings implicate AcPb as an additional component of the highly regulated IL-1 system and suggest it may play a role in modulating CNS responses to IL-1 and the interplay between inflammation and neuronal survival.

In this work we used a new strategy designed to reduce the size of the library that needs to be explored in family shuffling to evolve new biphenyl dioxygenases (BPDOs). Instead of shuffling the whole gene, we have targeted a fragment of bphA that is critical for enzyme specificity. We also describe a new protocol to screen for more potent BPDOs that is based on the detection of catechol metabolites from chlorobiphenyls. Several BphA variants with extended potency to degrade polychlorinated biphenyls (PCBs) were obtained by shuffling critical segments of bphA genes from Burkholderia sp. strain LB400, Comamonas testosteroni B-356, and Rhodococcus globerulus P6. Unlike all parents, these variants exhibited high activity toward 2,2-, 3,3-, and 4,4-dichlorobiphenyls and were able to oxygenate the very persistent 2,6-dichlorobiphenyl. The data showed that the replacement of a short segment ( 335 TFNNIRI 341 ) of LB400 BphA by the corresponding segment ( 333 GINTIRT 339 ) of B-356 BphA or P6 BphA contributes to relax the enzyme toward PCB substrates.Biphenyl dioxygenase (BPDO) is the first enzyme of the biphenyl (BPH) catabolic pathway. BPDO comprises three components: the iron-sulfur oxygenase (ISP BPH ) made up of ␣ (M r ϭ 51,000) and ␤ (M r ϭ 22,000) subunits, the ferredoxin (FER BPH , M r ϭ 12,000), and the ferredoxin reductase (RED BPH , M r ϭ 43,000). The encoding genes for both Burkholderia sp. strain LB400 (15, 16) and Comamonas testosteroni B-356 (35) are bphA (ISP BPH ␣ subunit), bphE (ISP BPH ␤ subunit), bphF (FER BPH ), and bphG (RED BPH ). ISP BPH catalyzes a 2,3-dihydroxylation of BPH. BPDO is of particular interest because of its potential application as biocatalyst to oxygenate priority pollutants such as polychlorinated BPHs (PCBs) or to manufacture fine chemicals.Despite their nearly identical amino acid sequences, the LB400 (15) and Pseudomonas pseudoalcaligenes strain KF707 BPDOs (36) display distinct ranges of PCB substrate (28). LB400 BPDO oxygenates 2,2Ј-dichlorobiphenyl (2,2ЈCB) and exhibits a 3,4-oxygenation of 2,2Ј,5,5ЈCB, whereas KF707 BPDO oxygenates 4,4ЈCB and is poorly active toward the ortho-substituted congeners (28). C. testosteroni B-356 and Rhodococcus globerulus P6 BPDOs, which are more distantly related to KF707 and LB400 BPDOs, poorly catalyze the oxygenation of para-substituted congeners and degrade fairly well 3,3ЈCB (11, 19). There is 75% amino acid sequence identity between the B-356 and LB400 BphAs (35), 64% amino acid sequence identity between P6 BphA1 and LB400 BphA (2), and 65% amino acid sequence identity between P6 BphA1 and B-356 BphA (35).Variant BPDOs that had inherited the catalytic features of both parents and exhibiting extended activities toward several tetra-and penta-substituted congeners were obtained by shuffling the very closely related LB400 bphA with KF707 bphA1 (9, 23). However, no novel BPDO has yet been described which can efficiently catalyze oxygenation of the most persistent congeners.Family shuffling of genes of lesser homology increases the sequenc...

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Glucocorticoids are potent regulators of the innate immune response, and alteration in this inhibitory feedback has detrimental consequences for the neural tissue. This study profiled and investigated functionally candidate genes mediating this switch between cell survival and death during an acute inflammatory reaction subsequent to the absence of glucocorticoid signaling. Oligonucleotide microarray analysis revealed that following lipopolysaccharide (LPS) intracerebral administration at striatum level, more modulated genes presented transcription impairment than exacerbation upon glucocorticoid receptor blockage. Among impaired genes we identified ceruloplasmin (Cp), which plays a key role in iron metabolism and is implicated in a neurodegenative disease. Microglial and endothelial induction of Cp is a natural neuroprotective mechanism during inflammation, because Cp-deficient mice exhibited increased iron accumulation and demyelination when exposed to LPS and neurovascular reactivity to pneumococcal meningitis. This study has identified genes that can play a critical role in programming the innate immune response, helping to clarify the mechanisms leading to protection or damage during inflammatory conditions in the CNS.