Pro- and anti-inflammatory cytokine gene expression in subcutaneous and visceral fat in severe obesity.

BACKGROUND AND AIMS: Pro-inflammatory molecules produced by adipose tissue have been implicated in the risk of cardiovascular (CV) disease in obesity. We investigated the expression profile of 19 pro-inflammatory and seven anti-inflammatory genes in subcutaneous adipose tissue (SAT) and in visceral adipose tissue (VAT) in 44 severely obese individuals who underwent bariatric surgery. METHODS AND RESULTS: SAT and VAT expressed an identical series of pro-inflammatory genes. Among these genes, 12 were significantly more expressed in SAT than in VAT while just one (IL18) was more expressed in VAT. The remaining genes were equally expressed. Among pro-inflammatory cytokines, both IL6 and IL8 were about 20 times more intensively expressed in SAT than in VAT. The expression of nine genes was highly associated in SAT and VAT. Only for three pro-inflammatory cytokines (IL8, IL18, SAA1) in SAT the gene expression in adipose tissue associated with the circulating levels of the corresponding gene products while no such an association was found as for VAT. CONCLUSIONS: The expression of critical pro-inflammatory genes is substantially higher in SAT than in VAT in individuals with morbid obesity. The variability in circulating levels of pro-inflammatory cytokines is, in small part and just for three pro-inflammatory cytokines, explained by underlying gene expression in SAT but not in VAT. These results point to a compartment-specific adipose tissue contribution to inflammation in obesity and indicate that abdominal SAT contributes more than VAT to the pro-inflammatory milieu associated with severe obesity.

Promotion of cell cycle progression by basic helix-loop-helix E2A.

Normal B-cell development requires the E2A gene and its encoded transcription factors E12 and E47. Current models predict that E2A promotes cell differentiation and inhibits G(1) cell cycle progression. The latter raises the conundrum of how B cells proliferate while expressing high levels of E2A protein. To study the relationship between E2A and cell proliferation, we established a tissue culture-based model in which the activity of E2A can be modulated in an inducible manner using E47R, an E47-estrogen fusion construct, and E47ERT, a dominant negative E47-estrogen fusion construct. The two constructs were subcloned into retroviral vectors and expressed in the human pre-B-cell line 697, the human myeloid progenitor cell line K562, and the murine fibroblastic cell line NIH 3T3. In both B cells and non-B cells, suppression of E2A activity by E47ERT inhibited G(1) progression and was associated with decreased expression of multiple cyclins including the G(1)-phase cyclin D2 and cyclin D3. Consistent with these findings, E2A null mice expressed decreased levels of cyclin D2 and cyclin D3 transcripts. In complementary experiments, ectopic expression of E47R promoted G(1) progression and was associated with increased levels of multiple cyclins, including cyclin D2 and cyclin D3. The induction of some cyclin transcripts occurred even in the absence of protein synthesis. We conclude that, in some cells, E2A can promote cell cycle progression, contrary to the present view that E2A inhibits G(1) progression.

Hybrid HIV/MSCV LTR enhances transgene expression of lentiviral vectors in human CD34(+) hematopoietic cells.

HIV-based lentiviral vectors can transduce nondividing cells, an important advantage over murine leukemia virus (MLV)-based vectors when transducing slowly dividing hematopoietic stem cells. However, we find that in human CD34(+) hematopoietic cells, the HIV-based vectors with an internal cytomegalovirus (CMV) promoter express transgenes 100- to 1,000-fold less than the MLV-based retroviral vector murine stem cell virus (MSCV). To increase the expression of the integrated lentivirus, we replaced CMV promoter with that of the Rous sarcoma virus or MSCV and obtained a modest augmentation in expression. A more dramatic effect was seen when the CMV enhancer/promoter was removed and the HIV long-terminal repeat (LTR) was replaced by a novel HIV/MSCV hybrid LTR. This vector retains the ability to transduce nondividing cells but now expresses its transgene (enhanced green fluorescent protein) 10- to 100-fold greater than the original HIV-based vector. When compared under identical conditions, the HIV vector with the hybrid LTR transduced a higher percentage of CD34(+) cells than the MSCV-based retroviral vector (19.4% versus 2.4%). The number of transduced cells and level of transgene expression remain constant over 5-8 weeks as determined by long-term culture-initiating cells, fluoresence-activated cell sorting, and nonobese diabetic/severe combined immunodeficiency repopulation assay.