CNS-derived extracellular vesicles from superoxide dismutase 1 (SOD1)G93A ALS mice originate from astrocytes and neurons and carry misfolded SOD1

Extracellular vesicles (EVs) are secreted by myriad cells in culture and also by unicellular organisms, and their identification in mammalian fluids suggests that EV release also occurs at the organism level. However, although it is clearly important to better understand EVs' roles in organismal biology, EVs in solid tissues have received little attention. Here, we modified a protocol for EV isolation from primary neural cell culture to collect EVs from frozen whole murine and human neural tissues by serial centrifugation and purification on a sucrose gradient. Quantitative proteomics comparing brain-derived EVs from nontransgenic (NTg) and a transgenic amyotrophic lateral sclerosis (ALS) mouse model, superoxide dismutase 1 (SOD1)^G93A, revealed that these EVs contain canonical exosomal markers and are enriched in synaptic and RNA-binding proteins. The compiled brain EV proteome contained numerous proteins implicated in ALS, and EVs from SOD1^G93A mice were significantly depleted in myelin-oligodendrocyte glycoprotein compared with those from NTg animals. We observed that brain- and spinal cord-derived EVs, from NTg and SOD1^G93A mice, are positive for the astrocyte marker GLAST and the synaptic marker SNAP25, whereas CD11b, a microglial marker, was largely absent. EVs from brains and spinal cords of the SOD1^G93A ALS mouse model, as well as from human SOD1 familial ALS patient spinal cord, contained abundant misfolded and nonnative disulfide-cross-linked aggregated SOD1. Our results indicate that CNS-derived EVs from an ALS animal model contain pathogenic disease-causing proteins and suggest that brain astrocytes and neurons, but not microglia, are the main EV source.

Protective effects of baicalein and wogonin against benzo[a]pyrene- and aflatoxin B(1)-induced genotoxicities

To evaluate the protective effects of baicalein and wogonin against benzo[a]pyrene- and aflatoxin (AF) B(1)-induced toxicities, the effects of these flavonoids on the genotoxicities and oxidation of benzo[a]pyrene and AFB(1) were studied in C57BL/6J mice. Baicalein and wogonin reduced benzo[a]pyrene and AFB(1) genotoxicities as monitored by the umuC gene expression response in Salmonella typhimurium TA1535/pSK1002. Baicalein added in vitro decreased liver microsomal benzo[a]pyrene hydroxylation (AHH) activity with an ic(50) of 33.9 +/- 1.4 microM at 100 microM benzo[a]pyrene. Baicalein also inhibited AFQ(1) and AFB(1)-epoxide formation from AFB(1) (50 microM) oxidation (AFO) with ic(50) values of 22.8 +/- 1.4 and 5.3 +/- 0.8 microM, respectively. However, the in vitro inhibitory effects of wogonin on AHH and AFO activities in liver microsomes were less than those of baicalein as inhibition by 500 microM wogonin was only about 51-65%. Treatment of mice with liquid diets containing 5 mM baicalein and wogonin resulted in 22 and 49% decreases in hepatic AHH activities, respectively. Baicalein treatment resulted in 39 and 32% decreases in AFQ(1) and AFB(1)-epoxide formation from liver microsomal AFO, respectively. Wogonin treatment resulted in 39 and 47% decreases in AFQ(1) and AFB(1)-epoxide formation, respectively. A 1-week pretreatment with wogonin significantly decreased hepatic DNA adduct formation in mice treated with 200 mg/kg of benzo[a]pyrene via gastrogavage. These in vitro and in vivo effects suggested that baicalein and wogonin might have beneficial effects against benzo[a]pyrene- and AFB(1)-induced hepatic toxicities and that wogonin had a stronger protective effect in vivo.

Effects of baicalein and wogonin on drug-metabolizing enzymes in C57BL/6J mice

Effects of baicalein and wogonin, the major flavonoids of Scutellariae radix, on cytochrome P450 (CYP), UDP-glucuronosyl transferase (UGT), and glutathione S-transferase (GST) were studied in C57BL/6J mice. One-week treatment of mice with a liquid diet containing 5 mM baicalein resulted in 29%, 14%, 36%, 28%, and 46% decreases of hepatic benzo(a)pyrene hydroxylation (AHH), benzphetamine N-demethylation (BDM), N-nitrosodimethylamine N-demethylation (NDM), nifedipine oxidation (NFO), and erythromycin N-demethylation (EMDM) activities, respectively. Treatment with a liquid diet containing 5 mM wogonin resulted in 43%, 22%, 21%, 24%, and 35% decreases of hepatic AHH, BDM, NDM, NFO, and EMDM activities, respectively. However, hepatic 7-methoxyresorufin O-demethylation (MROD) activity was increased and decreased by baicalein- and wogonin-treatments, respectively. Similar modulation was observed with caffeine 3-demethylation (CDM) activity. Immunoblot analysis showed that the levels of hepatic CYP2E1 and CYP3A proteins were decreased by both baicalein- and wogonin-treatments. Hepatic CYP1A2 protein level was increased by baicalein but decreased by wogonin. In extrahepatic tissues, renal AHH activity was decreased by wogonin whereas pulmonary AHH, 7-ethoxyresorufin O-deethylation (EROD), and MROD activities were increased by both flavonoids. Both baicalein and wogonin strongly increased CYP1A protein level in mouse lung. Hepatic and renal UGT activities toward p-nitrophenol were suppressed by baicalein- and wogonin-treatments. However, cytosolic GST activity was not affected by flavonoids. These results suggest that ingestion of baicalein or wogonin can modulate drug-metabolizing enzymes and the modulation shows tissue specificity.