FABP4 Dynamics in Obesity: Discrepancies in Adipose Tissue and Liver Expression Regarding Circulating Plasma Levels.

BACKGROUND FABP4 is predominantly expressed in adipose tissue, and its circulating levels are linked with obesity and a poor atherogenic profile. OBJECTIVE In patients with a wide BMI range, we analyze FABP4 expression in adipose and hepatic tissues in the settings of obesity and insulin resistance. Associations between FABP4 expression in adipose tissue and the FABP4 plasma level as well as the main adipogenic and lipolytic genes expressed in adipose tissue were also analyzed. METHODS The expression of several lipogenic, lipolytic, PPAR family and FABP family genes was analyzed by real time PCR. FABP4 protein expression in total adipose tissues and its fractions were determined by western blot. RESULTS In obesity FABP4 expression was down-regulated (at both mRNA and protein levels), with its levels mainly predicted by ATGL and inversely by the HOMA-IR index. The BMI appeared as the only determinant of the FABP4 variation in both adipose tissue depots. FABP4 plasma levels showed a significant progressive increase according to BMI but no association was detected between FABP4 circulating levels and SAT or VAT FABP4 gene expression. The gene expression of FABP1, FABP4 and FABP5 in hepatic tissue was significantly higher in tissue from the obese IR patients compared to the non-IR group. CONCLUSION The inverse pattern in FABP4 expression between adipose and hepatic tissue observed in morbid obese patients, regarding the IR context, suggests that both tissues may act in a balanced manner. These differences may help us to understand the discrepancies between circulating plasma levels and adipose tissue expression in obesity.

Rab18 dynamics in adipocytes in relation to lipogenesis, lipolysis and obesity.

Lipid droplets (LDs) are organelles that coordinate lipid storage and mobilization, both processes being especially important in cells specialized in managing fat, the adipocytes. Proteomic analyses of LDs have consistently identified the small GTPase Rab18 as a component of the LD coat. However, the specific contribution of Rab18 to adipocyte function remains to be elucidated. Herein, we have analyzed Rab18 expression, intracellular localization and function in relation to the metabolic status of adipocytes. We show that Rab18 production increases during adipogenic differentiation of 3T3-L1 cells. In addition, our data show that insulin induces, via phosphatidylinositol 3-kinase (PI3K), the recruitment of Rab18 to the surface of LDs. Furthermore, Rab18 overexpression increased basal lipogenesis and Rab18 silencing impaired the lipogenic response to insulin, thereby suggesting that this GTPase promotes fat accumulation in adipocytes. On the other hand, studies of the β-adrenergic receptor agonist isoproterenol confirmed and extended previous evidence for the participation of Rab18 in lipolysis. Together, our data support the view that Rab18 is a common mediator of lipolysis and lipogenesis and suggests that the endoplasmic reticulum (ER) is the link that enables Rab18 action on these two processes. Finally, we describe, for the first time, the presence of Rab18 in human adipose tissue, wherein the expression of this GTPase exhibits sex- and depot-specific differences and is correlated to obesity. Taken together, these findings indicate that Rab18 is involved in insulin-mediated lipogenesis, as well as in β-adrenergic-induced lipolysis, likely facilitating interaction of LDs with ER membranes and the exchange of lipids between these compartments. A role for Rab18 in the regulation of adipocyte biology under both normal and pathological conditions is proposed.

HERV-W polymorphism in chromosome X is associated with multiple sclerosis risk and with differential expression of MSRV.

BACKGROUND Multiple Sclerosis (MS) is an autoimmune demyelinating disease that occurs more frequently in women than in men. Multiple Sclerosis Associated Retrovirus (MSRV) is a member of HERV-W, a multicopy human endogenous retroviral family repeatedly implicated in MS pathogenesis. MSRV envelope protein is elevated in the serum of MS patients and induces inflammation and demyelination but, in spite of this pathogenic potential, its exact genomic origin and mechanism of generation are unknown. A possible link between the HERV-W copy on chromosome Xq22.3, that contains an almost complete open reading frame, and the gender differential prevalence in MS has been suggested. RESULTS MSRV transcription levels were higher in MS patients than in controls (U-Mann-Whitney; p = 0.004). Also, they were associated with the clinical forms (Spearman; p = 0.0003) and with the Multiple Sclerosis Severity Score (MSSS) (Spearman; p = 0.016). By mapping a 3 kb region in Xq22.3, including the HERV-W locus, we identified three polymorphisms: rs6622139 (T/C), rs6622140 (G/A) and rs1290413 (G/A). After genotyping 3127 individuals (1669 patients and 1458 controls) from two different Spanish cohorts, we found that in women rs6622139 T/C was associated with MS susceptibility: [χ2; p = 0.004; OR (95% CI) = 0.50 (0.31-0.81)] and severity, since CC women presented lower MSSS scores than CT (U-Mann-Whitney; p = 0.039) or TT patients (U-Mann-Whitney; p = 0.031). Concordantly with the susceptibility conferred in women, rs6622139*T was associated with higher MSRV expression (U-Mann-Whitney; p = 0.003). CONCLUSIONS Our present work supports the hypothesis of a direct involvement of HERV-W/MSRV in MS pathogenesis, identifying a genetic marker on chromosome X that could be one of the causes underlying the gender differences in MS.

Umbilical cord blood transplantation from unrelated donors in patients with Philadelphia chromosome-positive acute lymphoblastic leukemia.

There are very few disease-specific studies focusing on outcomes of umbilical cord blood transplantation for Philadelphia chromosome-positive acute lymphoblastic leukemia. We report the outcome of 45 patients with Philadelphia chromosome-positive acute lymphoblastic leukemia who underwent myeloablative single unit cord blood transplantation from unrelated donors within the GETH/GITMO cooperative group. Conditioning regimens were based on combinations of thiotepa, busulfan, cyclophospamide or fludarabine, and antithymocyte globulin. At the time of transplantation, 35 patients (78%) were in first complete remission, four (8%) in second complete remission and six (14%) in third or subsequent response. The cumulative incidence of myeloid engraftment was 96% at a median time of 20 days and significantly better for patients receiving higher doses of CD34(+) cells. The incidence of acute grade II-IV graft-versus-host disease was 31%, while that of overall chronic graft-versus-host disease was 53%. Treatment-related mortality was 17% at day +100 and 31% at 5 years. The 5-year relapse, event-free survival and overall survival rates were 31%, 36% and 44%, respectively. Although the event-free and overall survival rates in patients without BCR/ABL transcripts detectable at time of transplant were better than those in whom BCR/ABL transcripts were detected (46% versus 24% and 60% versus 30%, respectively) these differences were not statistically significant in the univariate analysis (P=0.07). These results demonstrate that umbilical cord blood transplantation from unrelated donors can be a curative treatment for a substantial number of patients with Philadelphia chromosome-positive acute lymphoblastic leukemia.