Context Identification of genes contributing to alcohol dependence will improve our understanding of the mechanisms underlying this disorder. Objective To identify susceptibility genes for alcohol dependence through a genome-wide association study (GWAS) and follow-up study in a population of German male inpatients with an early age at onset. Design The GWAS included 487 male inpatients with DSM-IV alcohol dependence with an age at onset below 28 years and 1,358 population based control individuals. The follow-up study included 1,024 male inpatients and 996 age-matched male controls. All subjects were of German descent. The GWAS tested 524,396 single nucleotide polymorphisms (SNPs). All SNPs with p<10-4 were subjected to the follow-up study. In addition, nominally significant SNPs from those genes that had also shown expression changes in rat brains after chronic alcohol consumption were selected for the follow-up step. Results The GWAS produced 121 SNPs with nominal p<10-4. These, together with 19 additional SNPs from homologs of rat genes showing differential expression, were genotyped in the follow-up sample. Fifteen SNPs showed significant association with the same allele as in the GWAS. In the combined analysis, two closely linked intergenic SNPs met genome-wide significance (rs7590720 p=9.72×10-9; rs1344694 p=1.69×10-8). They are located on chromosome 2q35, a region which has been implicated in linkage studies for alcohol phenotypes. Nine SNPs were located in genes, including CDH13 and ADH1C genes which have been reported to be associated with alcohol dependence. Conclusion This is the first GWAS and follow-up study to identify a genome-wide significant association in alcohol dependence. Further independent studies are required to confirm these findings.

Recent work has demonstrated that apo E secretion and accumulation increase in the regenerating peripheral nerve. The fact that apoE, in conjunction with apoA-I and LDL receptors, participates in a well-established lipid transfer system raised the possibility that apoE is also involved in lipid transport in the injured nerve. In the present study of the crushed rat sciatic nerve, a combination of techniques was used to trace the cellular associations of apoE, apoA-I, and the LDL receptor during nerve repair and to determine the distribution of lipid at each stage. After a crush injury, as axons died and Schwann cells reabsorbed myelin, resident and monocyte-derived macrophages produced large quantities of apoE distal to the injury site. As axons regenerated in the first week, their tips contained a high concentration of LDL receptors. After axon regeneration, apoE and apoA-I began to accumulate distal to the injury site and macrophages became increasingly cholesterol-loaded. As remyelination began in the second and third weeks after injury, Schwann cells exhausted their cholesterol stores, then displayed increased LDL receptors. Depletion of macrophage cholesterol stores followed over the next several weeks. During this stage of regeneration, apoE and apoA-I were present in the extracellular matrix as components of cholesterol-rich lipoproteins. Our results demonstrate that the regenerating peripheral nerve possesses the components of a cholesterol transfer mechanism, and the sequence of events suggests that this mechanism supplies the cholesterol required for rapid membrane biogenesis during axon regeneration and remyelination.

Alzheimer's disease (AD) is characterized by the accumulation of fibrillar amyloid-beta (Abeta) peptides to form amyloid plaques. Understanding the balance of production and clearance of Abeta peptides is the key to elucidating amyloid plaque homeostasis. Microglia in the brain, associated with senile plaques, are likely to play a major role in maintaining this balance. Here, we show that heat-shock proteins (HSPs), such as HSP90, HSP70, and HSP32, induce the production of interleukin 6 and tumor necrosis factor alpha and increase the phagocytosis and clearance of Abeta peptides. This suggests that microglial interaction with Abeta peptides is highly regulated by HSPs. The mechanism of microglial activation by exogenous HSPs involves the nuclear factor kB and p38 mitogen-activated protein kinase pathways mediated by Toll-like receptor 4 activation. In AD brains, levels of HSP90 were increased in both the cytosolic and membranous fractions, and HSP90 was colocalized with amyloid plaques. These observations suggest that HSP-induced microglial activation may serve a neuroprotective role by facilitating Abeta clearance and cytokine production

Dendritic cells (DCs) are specialized antigen-presenting cells characterized by their ability to migrate into target sites, process antigens, and activate naive T cells. In this study, we analyzed the biological activity and intracellular signaling of adenosine by using reverse transcriptase-polymerase chain reaction assays to investigate mRNA expression of A(1), A(2a) and A(3) adenosine receptors in immature and mature human DCs. Functional experiments on adenosine stimulation showed chemotaxis, intracellular calcium transients, and actin polymerization, but no activation of adenylate cyclase in immature DCs. Experiments with receptor isotype-selective agonists and antagonists as well as pertussis toxin revealed that chemotaxis, calcium transients, and actin polymerization were mediated via G(i-) or G(0-)protein-coupled A(1) and A(3) receptors. Maturation of DCs induced by lipopolysaccharide (LPS) resulted in down-regulation of A(1) and A(3) receptor mRNAs, although A(2a) receptor mRNA was still expressed. However, in LPS-differentiated DCs, adenosine and an A(2a) receptor agonist stimulated adenylate cyclase activity, enhanced intracellular cAMP levels, and inhibited interleukin 12 (IL-12) production. These effects could be completely prevented by pretreatment with A(2) receptor antagonist. These findings strongly suggest that adenosine has important but distinct biological effects in DCs activity as a chemotaxin for immature DCs and as a modulator of IL-12 production in mature DCs. These effects can be explained by differential expression of adenosine receptor subtypes.

Sphingosine 1-phosphate (S1P) is a potent extracellular lysolipid phosphoric acid mediator that is released after IgE-stimulation of mast cells. Here we investigated the biological activity and intracellular signaling of S1P on human dendritic cells (DC), which are specialized antigen presenting cells with the ability to migrate into peripheral tissues and lymph nodes, as well as control the activation of naive T cells. We show that immature and mature DC express the mRNA for different S1P receptors, such as endothelial differentiation gene (EDG)-1, EDG-3, EDG-5, and EDG-6. In immature DC, S1P stimulated pertussis toxin-sensitive Ca2+ increase actin-polymerization and chemotaxis. These responses were lost by DC matured with lipopolysaccharide. In maturing DC, however, S1P inhibited the secretion of tumor necrosis factor alpha and interleukin (IL)-12, whereas it enhanced secretion of IL-10. As a consequence, mature DC exposed to S1P showed a reduced and increased capacity to generate allogeneic Th1 and Th2 responses, respectively. In summary, our study implicates that S1P might regulate the trafficking of DC and ultimately favor Th2 lymphocyte-dominated immunity.