The flavonoids comprise a large class of low-molecular-weight plant metabolites ubiquitously distributed in food plants. These dietary antioxidants exert significant antitumor, antiallergic, and anti-inflammatory effects. The molecular mechanisms of their biological effects remain to be clearly understood. We investigated the anti-inflammatory potentials of a safe, common dietary flavonoid component, quercetin, for its ability to modulate the production and gene expression of the proinflammatory cytokine tumor necrosis factor alpha (TNF-␣) by human peripheral blood mononuclear cells (PBMC). Our results showed that quercetin significantly inhibited TNF-␣ production and gene expression in a dose-dependent manner. Our results provide direct evidence of the anti-inflammatory effects of quercetin by PBMC, which are mediated by the inhibition of the proinflammatory cytokine TNF-␣ via modulation of NF-␤1 and I␤.The natural antioxidant flavonoids constitute significant components of the diet and display a diverse array of biological effects (16,19,21,26). Polyphenolic compounds, including a large class of flavonoids, are enriched in certain vegetables, fruits, seeds, and beverages (e.g., tea and wine) and are regarded as a class of semiessential nutrients for humans. Dietary intake rich in these compounds has been suggested to improve the health of individuals and decrease the risk of cardiovascular disease. The beneficial effects of flavonoids have been attributed to their antioxidant and anti-inflammatory properties (18,19,31). The effects of flavonoids, including quercetin, on a variety of inflammatory processes and immune functions have been extensively reviewed (4,6,11,17,25,27,28,40). Tumor necrosis factor alpha (TNF-␣) is one of the major proinflammatory cytokines involved in the pathogenesis of chronic inflammatory diseases and is modulated by oxidative stress (5, 35). TNF-␣ is a multifunctional cytokine that regulates the growth, proliferation, differentiation, and viability of activated leukocytes. TNF-␣ also triggers the cellular release of other cytokines, chemokines, or inflammatory mediators and displays antiviral and antimicrobial effects (1, 2, 39).Numerous signaling cascades have been elucidated in promotion of proinflammatory conditions by proinflammatory cytokines, such as TNF-␣, which involves the activation of inducible transcriptional factors (1,12,13,14,29,39). NF-␤ is one of the principal inducible transcription factors whose modulation triggers a cascade of signaling events involving an integrated sequence of protein-regulated steps, some of which are potential key targets for intervention in treating inflammatory conditions (3,7,20,29,33,34). Previous studies have shown that quercetin inhibits lipopolysaccharide (LPS)-stimulated NF-␤ activation in RAW 264.7 macrophage (8, 37) and also inhibits LPS-induced I␤ phosphorylation in bone marrowderived macrophage (11). Although quercetin exhibits several biological effects, the molecular mechanisms of its anti-inflammatory effects by peripheral blood ...

Alteration in cytoskeletal organization appears to underlie mechanisms of gravity sensitivity in space-flown cells. Human T lymphoblastoid cells (Jurkat) were flown on the Space Shuttle to test the hypothesis that growth responsiveness is associated with microtubule anomalies and mediated by apoptosis. Cell growth was stimulated in microgravity by increasing serum concentration. After 4 and 48 h, cells filtered from medium were fixed with formalin. Post-flight, confocal microscopy revealed diffuse, shortened microtubules extending from poorly defined microtubule organizing centers (MTOCs). In comparable ground controls, discrete microtubule filaments radiated from organized MTOCs and branched toward the cell membrane. At 4 h, 30% of flown, compared to 17% of ground, cells showed DNA condensation characteristic of apoptosis. Time-dependent increase of the apoptosis-associated Fas/ APO-1 protein in static flown, but not the in-flight 1 g centrifuged or ground controls, confirmed microgravity-associated apoptosis. By 48 h, ground cultures had increased by 40%. Flown populations did not increase, though some cells were cycling and actively metabolizing glucose. We conclude that cytoskeletal alteration, growth retardation, and metabolic changes in space-flown lymphocytes are concomitant with increased apoptosis and time-dependent elevation of Fas/APO-1 protein. We suggest that reduced growth response in lymphocytes during spaceflight is linked to apoptosis.

The pathogenesis of human immunodeficiency virus (HIV) associated encephalopathy is attributed to infiltration of the central nervous system (CNS) by HIV-1 infected mononuclear cells that transmigrate across the blood brain barrier (BBB). The endothelial tight junctions (TJ) of the blood brain barrier (BBB) play a critical role in controlling cellular traffic into the CNS. Neuropathogenesis of HIV-1 is exacerbated by drugs of abuse such as methamphetamine (Meth) which are capable of dysregulating BBB function. HIV-1 viral proteins like gp120 are both neurotoxic and cytotoxic and have been implicated in the development of HIV-1 dementia (HAD). We hypothesize that gp120 in synergy with Meth can alter BBB permeability via the modulation of tight junction expression. We investigated the effect of Meth and/or gp120 on the basal expression of TJ proteins ZO-1, JAM-2, Occludin, Claudin-3 and Claudin-5, using in vitro cultures of the primary brain microvascular endothelial cells (BMVEC). Further, the functional effects of TJ modulation were assessed using an in vitro BBB model, that allowed measurement of BBB permeability using TEER measurements and transendothelial migration of immunocompetent cells. Our results show that both Meth and gp120 individually and in combination, modulated TJ expression, and these effects involved Rho-A activation. Further, both Meth and gp120 alone and in combination significantly decreased transendothelial resistance across the in vitro BBB and the enhanced transendothelial migration of immunocompetent cells across the BBB. An understanding of the mechanisms of BBB breakdown that lead to neurotoxicity is crucial to the development of therapeutic modalities for Meth abusing HAD patients.

Well-defined tertiary amine-functionalized cationic polylactides (CPLAs) are synthesized by thiol-ene click functionalization of an allyl-functionalized polylactide, and utilized here for the delivery of interleukin-8 (IL-8) siRNA via CPLA-IL-8 siRNA nanoplexes. The CPLAs possess remarkable hydrolytic degradability, and their cytotoxicity is relatively low. The CPLA-IL-8 siRNA nanoplexes can be readily taken up by prostate cancer cells, resulting in significant IL-8 gene silencing. It is found that the degradability and cytotoxicity of CPLAs, as well as the transfection efficiency of the CPLA-IL-8 siRNA nanoplexes, positively correlate with the amine mol% of CPLAs.