Yoshio Tsukamoto

Transforming growth factor-β-induced gene expression of monocyte chemoattractant JE in mouse osteoblastic cells, MC3T3-E1

A recent study demonstrated that PDGF-inducible JE is an inflammatory cytokine that directs chemotactic activity of monocytes. Accumulation of monocyte/macrophage lineage cells at site of bone tissue sites is very important for formation of multinucleate osteoclasts, which mediate bone resorption. Since transforming growth factor-beta (TGF-beta) is a potent regulator in bone remodeling, we examined whether TGF-beta induced JE gene expression in mouse osteoblastic cells, MC3T3-E1. TGF-beta induced a maximum JE mRNA expression at 3 hr after initiation of the cytokine treatment. This maximal expression was observed in when TGF-beta was used at a concentration of 1 ng/ml. The chemotactic activity for human monocytes was detected in conditioned medium of TGF-beta-treated cells, and the chemotactic activity was neutralized by anti-JE serum treatment.

Role of lysine residue at 7th position of wasp chemotactic peptides

Most of chemotactic peptides isolated from various kinds of wasp venom have lysine residue at 7th (or 8th) position, but only a chemotactic peptide from Icaria sp. has no basic amino acid residues in the sequence. The relation of chemotaxis with other biochemical activities such as superoxide generation and lysosomal enzyme release from guinea pig neutrophils was studied by the use of substitution analogs of Icaria chemotactic peptide at 7th position. Findings revealed two distinct ways of chemoattractant signal transduction in neutrophils.

Macrophage-produced oxygen radical generating activities for polymorphonuclear leukocytes

Guinea pig peritoneal macrophages were stimulated in vitro by bacterial lipopolysaccharide. After incubation, the supernatants of macrophage cultures were collected and tested for O2− production on guinea pig peritoneal polymorphonuclear leukocytes. The supernatants of macrophage cultures stimulated by lipopolysaccharide had significantly higher levels of O2−-generating activities in polymorphonuclear leukocytes, and these activities appeared in the macrophage cultures within 2 h after stimulation by lipopolysaccharide However, the supernatants obtained from the nonstimulated cultures could not produce these activities. These activities disappeared with heating or trypsin and were not produced in macrophage cultures by incubation with cycloheximide.

Characterization of leukocyte chemotactic activity of bacteriocin from Streptococcus mutans Rm-10.

Bacteriocins have several biological activities in addition to their antibacterial effect. We investigated the chemotactic properties and mode of action of purified streptococcal bacteriocin. Bacteriocin purified from a culture supernatant ofStreptococcus mutans (S. mutans) Rm-10 induced chemotaxis of human polymorphonuclear leukocytes and monocytes. Following purification, leukocyte migration appeared in one bacteriocin fraction, and this migration was dependent on the concentration gradient in dilution ranges from 1/960 to 1/15. Chemotactic activity of the bacteriocin was heat labile and trypsin sensitive. Moreover, preincubation of bacteriocin with varying dilutions of its antiserum prepared in rabbits resulted in a significant loss of the chemotactic activity.

The in vitro effects of semiconductor laser irradiation on inflammation: laser irradiation did not affect monocyte infiltration

The effects of supernatants following irradiation of lymphocytes and monocytes with a semiconductor laser, on monocyte chemotaxis were investigated in vitro. Human peripheral lymphocytes and monocytes were obtained from healthy adult donors, and were suspended in medium, following laser irradiation. The laser irradiation (wavelength 900 nm, output power 1.5 mW) was carried out in the pulse wave mode at doses of 0.1 J cm-2 in total. After irradiation, the lymphocytes and monocytes were incubated with or without several kinds of stimulants for varying time periods. The supernatants of these cultures were then assayed for human monocyte chemotaxis. Through these experiments, we were unable to detect any significant levels of stimulative or depressive effects due to laser irradiation of the lymphocytes and monocytes, on the production of monocyte chemotactic activity.

Effect of Cepharantin on leukocyte chemotaxis induced by venom peptides.

Cepharanthin (CR), one of biscoclaurine alkaloids, are utilized for treatment in a wide variety of diseases, and also for the stings of wasps. In order to describe the pharmacological actions of CR, it was determined the effects of CR on leukocyte migration induced by chemotactic peptides isolated from venom sac of Vespinae. Vespid chemotactic peptides were isolated from Vespa tropica (VesCP-T) and Vespa mandarinia (Ves CP-M) . Human polymorphonuclear leukocyte (PMNL) and mononuclear leukocyte (MNL) were separated from peripheral blood, and in vitro chemotaxis assay was performed with membrane filter and multi-well chemotaxis chamber. VesCP-T and VesCP-M showed significant levels of chemotactic activities for PMNL and MNL, and these chemotactic migrations to VesCPs were decreased by addition of CR at a concentration over 10-5M. However, leukocyte migration induced by formyl peptide, synthetic chemoattractant, and buffer control were also depressed. These results suggest that the depression of leukocyte chemotaxis by CR in vitro was attributed to the direct action of CR to leukocytes.