Effects of various cytochalasins on the IgE-mediated serotonin release from rat basophilic leukemia cells

Enhanced production of aspochalasin D through genetic engineering of Aspergillus flavipes

Aspochalasin D (AD) belongs to the polyketide-amino acid hybrid natural products with anti-cancer, anti-bacterial, and anti-fouling bioactivities. However, the low production limits its further application. In this study, AD was separated and identified from Aspergillus flavipes 3.17641. Next, besides the optimization of culture conditions using a single-factor experiment and response surface methodology, metabolic engineering was employed to increase the AD production. It shows that the deletion of the shunt gene aspoA and overexpression of the pathway-specific regulator aspoG significantly improve the AD production. Its production reached to 812.1 mg/L under the optimized conditions, with 18.5-fold increase. Therefore, this study not only provides a general method for improving the production of similar natural products in other fungi, but also enables the further biological function development of AD in agriculture and pharmaceutical. KEY POINTS: • The Aspochalasin D (AD) production was improved by optimizing culture conditions. • The deletion of the shunt gene aspoA increased the AD production. • Overexpression of the pathway regulator aspoG further improved the AD production.

ATP plays a role in neurite stimulation with activated mast cells

Previously, we showed that nerve-mast cell cross-talk can occur bidirectionally and that substance P is a mediator to activate mast cells. Here, we have studied the mediators to activate nerves cocultured with mast cells. Addition of antigen to the cocultures of superior cervical ganglia (SCG) and rat basophilic leukemia cells (RBLs) elicited Ca(2+) response in RBLs and after a lag period induced Ca(2+) signal in SCG neurites. Pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid (purinergic receptor antagonist) or apyrase (ATP-hydrolyzing enzyme) reduced the Ca(2+) signals in neurites, indicating that ATP released from activated mast cells was one of important mediators to activate nerves.

Immunological functions of soy sauce: hypoallergenicity and antiallergic activity of soy sauce

Soy sauce is a traditional fermented seasoning of East Asian countries and is available throughout the world. In Japanese soy sauce (shoyu), soybeans and wheat are the two main raw materials, used in almost the same quantity. Proteins of the raw materials are completely degraded into peptides and amino acids by microbial proteolytic enzymes after fermentation, and no allergens of the raw materials are present in soy sauce. In contrast, polysaccharides originating from the cell wall of soybeans are resistant to enzymatic hydrolyses. These polysaccharides are present in soy sauce even after fermentation and termed shoyu polysaccharides (SPS). Soy sauce generally contains about 1% (w/v) SPS and SPS exhibit potent antiallergic activities in vitro and in vivo. Furthermore, an oral supplementation of SPS is an effective intervention for patients with allergic rhinitis in two double-blind placebo-controlled clinical studies. In conclusion, soy sauce would be a potentially promising seasoning for the treatment of allergic diseases through food because of its hypoallergenicity and antiallergic activity.

Synthetic studies on glycosphingolipids from Protostomia phyla: synthesis of amphoteric glycolipid analogues containing a phosphocholine residue from the earthworm Pheretima hilgendorfi

Two kinds of amphoteric glycosphingolipid analogues from the earthworm Pheretima hilgendorfi were synthesized as follows: The key reaction is a coupling of a phosphocholine group at the position C-6 of 1 and 6 which was attempted using 2-chloro-2-oxo-1,3,2-dioxaphospholane, followed by reaction of the resulting cyclic phosphate intermediate with anhydrous trimethylamine to give 2 and 7. Subsequent debenzylation afforded target compounds (3, 8). Their ability to inhibit the histamine release in vitro was examined.

Antiallergic activities of rabdosiin and its related compounds: chemical and biochemical evaluations

We examined the effects of caffeic acid-containing compounds such as chlorogenic acid, rosmarinic acid and rabdosiin on anti-allergic activities involving active oxygens scavenging activity as well as inhibitory activities of hyaluronidase and beta-hexosaminidase release. Rabdosiin exhibited the highest hyaluronidase-inhibitory activity and scavenging activities against active oxygens species such as superoxide anion radicals and hydroxyl radicals among the tested compounds. Both rabdosiin and caffeic acid inhibited beta-hexosaminidase release from cultured cells more than 90% at 2 mM. The inhibition by rosmarinic acid and chlorogenic acid were weaker than that of rabdosiin. From these results, rabdosiin has been proposed to possess anti-allergic activity.

Simple spectrophotometric analysis of passive and active ear cutaneous anaphylaxis in the mouse

Homologous passive cutaneous anaphylaxis (PCA) and active cutaneous anaphylaxis (ACA) to ovalbumin and DNP-hapten were studied in the ears of female BALB/c mice by means of assessing Evans blue dye leakage. For the quantitative evaluation of PCA and ACA, a hand-held spectrophotometer and the conventional colorimetric method were used to detect the amount of extravasated dye. The value of deltaE*ab (a numerical expression of color) obtained with the hand-held spectrophotometer and the amount of extravasated dye showed a good correlation. In the mouse ear, the sensitivity of PCA reaction was comparable to that of PCA in the rat, and deltaE*ab in the PCA and ACA reactions correlated well with the dilutions of sera and of the antigen, respectively. Thus, using a hand-held spectrophotometer is a simple, quantitative and sensitive method for ascertaining the extent of immediate-type hypersensitivity in the mouse.

Suppression of anaphylactic shock in sensitized guinea pigs by cytochalasin D

A new highly effective pathogenetic therapy for anaphylactic reaction in vivo has been suggested. Forty-three guinea pigs, presensitized with horse serum and divided into two groups, were injected intracardially with 1 ml of 1.6 x 10(-4) M cytochalasin D and 1 ml of 1.6 x 10(-5) M cytochalasin D in DMSO solution at various times before being challenged with the serum. Experimental data not only showed that anaphylactic reaction can be suppressed in vivo by blocking cytoskeletal activity but also demonstrated different pharmacodynamic characteristics of cytochalasin D on clinical course, gravity and outcome of anaphylactic shock in sensitized guinea pigs, depending on the interval between administration of the drug and allergen.

Possible involvement of phosphorylation of a 36,000-dalton protein of rat basophilic leukemia (RBL-2H3) cell membranes in serotonin release

Phosphorylation of a 36,000-dalton (36k-Da) protein of rat basophilic leukemia (RBL-2H3) cell membranes was investigated. This phosphoprotein has been suggested to be the beta-subunit protein of the immunogloblin E (IgE) receptor of RBL-2H3 cells [Teshima et al., Biochem. biophys. Res. Commun. 125, 867-874 (1984)]. Phospholipids such as phosphatidyl serine, phosphatidyl inositol and phosphatidyl ethanolamine, which are known to be activators of protein kinase C, enhanced the phosphorylation of the 36K-Da protein. In contrast, 1-(5-isoquinoline sulfonyl)-2-methylpiperazine (H-7) which has been identified as a potent inhibitor of protein kinase C in vitro decreased incorporation of radioactive phosphate from [gamma-32P]ATP into this protein. These results indicate that the phosphorylation of the 36K-Da protein of RBL-2H3 cell membranes is catalyzed by protein kinase C. H-7 also inhibited the release of serotonin from RBL-2H3 cells stimulated with an antigen or calcium ionophore A23187 and 12-O-tetradecanoyl phorbol 13-acetate (TPA). Treatment of the antigen-stimulated cells with TPA caused a synergistic effect on the serotonin release. A similar effect was obtained by treatment of A23187-stimulated cells with TPA or 1-oleoyl-2-acetyl glycerol.