Hepatocyte toll-like receptor 2 expression in vivo and in vitro: role of cytokines in induction of rat TLR2 gene expression by lipopolysaccharide.

We and others have demonstrated previously that cytokines, including interleukin-1 (IL-1) and tumor necrosis factor-alpha (TNFalpha), regulate LPS recognition proteins such as CD14 in the liver and on hepatocytes. Based on recent findings that the mammalian homologue of Drosophila Toll participates in LPS signaling, we examined the regulation of Toll-Like Receptor (TLR) gene expression by cytokines in vitro and its distribution in vivo with a focus on the liver as a site of host-microbe interaction. Our results show that IL-1beta and/or TNFalpha participate in the upregulation of TLR2 mRNA levels in hepatocytes. Rats treated concurrently with LPS and antagonists of the IL-1 or TNFalpha receptor demonstrated significantly reduced LPS-induced hepatic expression of TLR2 compared to animals treated with LPS alone. The increase in hepatic TLR2 mRNA expression was associated with enhanced transcription as determined by nuclear run-on analysis. LPS treatment in vivo caused a marked TLR2 mRNA up-regulation in all of the tissues examined, with liver showing the highest expression. The high level of TLR2 expression in the liver may have important implications for pathogen-host interactions or microbial signaling.

Gene therapy and tissue engineering.

Gene therapy, the science of altering cellular function or structure at a molecular level, is currently one of the most exciting fields of research across medical specialties. By replacing lost or defective genes or adding genes known to produce proteins with beneficial effects, investigators hope to treat and possibly cure everything from inborn errors of metabolism to acquired diseases, such as emphysema and atherosclerosis. Genetic modification of engineered tissue, the offspring of these two fields, offers the promise of not simply replacing tissue, but improving on the restoration. The studies presented in this article demonstrate many of the principles that form the basis of gene therapy and provide insight into the potential of this emerging technology.

Impaired wound healing and angiogenesis in eNOS-deficient mice.

A role for nitric oxide (NO) in wound healing has been proposed; however, the absolute requirement of NO for wound healing in vivo and the contribution of endothelial NO synthase (eNOS) have not been determined. Experiments were carried out using eNOS gene knockout (KO) mice to determine the requirement for eNOS on wound closure and wound strength. Excisional wound closure was significantly delayed in the eNOS KO mice (29.4 +/- 2.2 days) compared with wild-type (WT) controls (20.2 +/- 0.4 days). At 10 days, incisional wound tensile strength demonstrated a 38% reduction in the eNOS KO mice. Because effective wound repair requires growth factor-stimulated angiogenesis, in vitro and in vivo angiogenesis assays were performed in the mice to assess the effects of eNOS deficiency on angiogenesis. Endothelial cell sprouting assays confirmed in vitro that eNOS is required for proper endothelial cell migration, proliferation, and differentiation. Aortic segments harvested from eNOS KO mice cultured with Matrigel demonstrated a significant reduction in endothelial cell sprouting and [(3)H]thymidine incorporation compared with WT mice at 5 days. Capillary ingrowth into subcutaneously implanted Matrigel plugs was significantly reduced in eNOS KO mice (2.67 +/- 0.33 vessels/plug) compared with WT mice (10.17 +/- 0.79 vessels/plug). These results clearly show that eNOS plays a significant role in facilitating wound repair and growth factor-stimulated angiogenesis.

Aortic diameter as a function of age, gender, and body surface area.

BACKGROUND: An aortic aneurysm is defined as a 50% or greater increase in diameter compared with normal levels or the level of the left renal vein. However, normal diameters for many aortic segments are not known, and the aortic segment at the left renal vein may be enlarged. The purpose of this study was to determine normal diameters of the thoracic and abdominal aortas in relationship to age, gender, and body size. METHODS: Aortic diameters (ADs) were determined at four anatomic levels: thoracic aorta, abdominal aorta at the celiac axis, renal arteries, and midway between the renal arteries and the bifurcation. ADs were determined with the use of a video analyzer and an electronic caliper. Computed tomographic scans (n = 389) obtained for nonvascular diagnoses were analyzed according to gender, age, height, weight, and body surface area (BSA). RESULTS: At all levels and in each decade the AD is significantly greater in men than in women (p < 0.0001). BSA is a better predictor of size than height or weight. AD increased with age at all levels, and there was a positive correlation between the AD and BSA and gender. Expected ADs for each aortic segment may be calculated according to regression equations. Age-, gender-, and BSA-matched patients with abdominal aortic aneurysms revealed significant enlargements in all proximal aortic segments. CONCLUSIONS: AD at a given level is a function of gender, age, and BSA. When these variables are known, it is possible to calculate an expected AD. The AD is greater at all levels in patients with abdominal aortic aneurysms and in men compared with women.