Il-Han Lee

New Biological Functions and Applications of High‐Molecular‐Mass Poly‐γ‐glutamic Acid

Ultra‐high‐molecular‐weight poly‐γ‐glutamic acid (γ‐PGA) is a most promising biodegradable polymer that is produced by Bacillus subtilis (chungkookjang). Attractive properties of γ‐PGA are that it is water soluble, anionic, biodegradable, and edible. Development of γ‐PGA has pursued in terms of cosmetics/skin care, bone care, nanoparticle for drug delivery system, hydrogel, and so on. Very recently, our research has shown that γ‐PGA can be used as an immune‐stimulating agent, especially at high molecular weight. This review presents the synthesis and production of high‐molecular‐weight γ‐PGA and its various applications in industrial fields.

Human papillomavirus type 16 E6-specific antitumor immunity is induced by oral administration of HPV16 E6-expressing Lactobacillus casei in C57BL/6 mice

Given that local cell-mediated immunity (CMI) against the human papillomavirus type 16 E6 (HPV16 E6) protein is important for eradication of HPV16 E6-expressing cancer cells in the cervical mucosa, the HPV16 E6 protein may be a target for the mucosal immunotherapy of cervical cancer. Here, we expressed the HPV16 E6 antigen on Lactobacillus casei (L. casei) and investigated E6-specific CMI following oral administration of the L. casei-PgsA-E6 to mice. Surface expression of HPV16 E6 antigens was confirmed and mice were orally inoculated with the L. casei-PgsA or the L. casei-PgsA-E6. Compared to the L. casei-PgsA-treated mice, significantly higher levels of serum IgG and mucosal IgA were observed in L. casei-PgsA-E6-immunized mice; these differences were significantly enhanced after boost. Consistent with this, systemic and local CMI were significantly increased after the boost, as shown by increased counts of IFN-γ-secreting cells in splenocytes, mesenteric lymph nodes (MLN), and vaginal samples. Furthermore, in the TC-1 tumor model, animals receiving the orally administered L. casei-PgsA-E6 showed reduced tumor size and increased survival rate versus mice receiving control (L. casei-PgsA) immunization. We also found that L. casei-PgsA-E6-induced antitumor effect was decreased by in vivo depletion of CD4+ or CD8+ T cells. Collectively, these results indicate that the oral administration of lactobacilli bearing the surface-displayed E6 protein induces T cell-mediated cellular immunity and antitumor effects in mice.

Oral Administration of Poly-γ-Glutamate Ameliorates Atopic Dermatitis in Nc/Nga Mice by Suppressing Th2-Biased Immune Response and Production of IL-17A

Atopic dermatitis (AD) is a chronic inflammatory skin disease that is closely related to dysregulation of the T helper type 1 and 2 (Th1)/Th2 balance. A previous study showed that high molecular mass poly-γ-glutamate (γ-PGA) isolated from Bacillus subtilis sp. Chungkookjang induces the production of IL-12 from dendritic cells (DCs). Here, we investigated the effect of γ-PGA on AD-like skin disease using an Nc/Nga mouse model. In vitro, γ-PGA activated DCs and induced IL-12 production in mice. In vivo, oral administration of γ-PGA markedly reduced the AD symptoms, similar to the response seen in the dexamethasone (Dex)-treated group. Treatment with γ-PGA also decreased the serum levels of IgG1, the skin levels of Th2 cytokines, the extent of skin inflammation, and the accumulation of mast cells. Furthermore, γ-PGA was effective against established AD, significantly decreasing serum IgE and Th2 cytokines in the inflamed tissue. Interestingly, the production of IL-17A in splenocytes was also suppressed by γ-PGA, indicating that it inhibits both Th2 and Th17 immune responses. Collectively, these results suggest that oral administration of γ-PGA could be a therapeutic strategy for treating AD via the modulation of Th2-biased immune responses in an Nc/Nga mouse model.

Distribution of human papillomavirus type 16 E6 and E7 gene variants in the progression of cervical dysplasia in Korean women.

Aim:  This cross‐sectional, hospital‐based study examined the distribution of human papillomavirus 16 E6 and E7 gene variants in Korean women with cervical lesions of varying degrees.