Strong immunostimulatory activity of AT-oligodeoxynucleotide requires a six-base loop with a self-stabilized 5′-C…G-3′ stem structure
Authors: Shimosato, Takeshi1; Kimura, Toshiro1; Tohno, Masanori1; Iliev, Iliyan Dimitrov1; Katoh, Shinichiro1; Ito, Yoshiyuki2; Kawai, Yasushi1; Sasaki, Takashi2; Saito, Tadao1; Kitazawa, Haruki1
Source: Cellular Microbiology, Volume 8, Number 3, March 2006 , pp. 485-495(11)
Publisher: Blackwell Publishing
Abstract:
Summary Lactobacillus gasseri OLL2716 has recently been discovered as a probiotic that suppresses the growth of Helicobacter pylori and reduces gastric mucosal inflammation in humans. This has resulted in the development of a new type of probiotic yoghurt `LG21' in Japan. In our previous study, we found an immunostimulatory AT5ACL oligodeoxynucleotide (AT-ODN) containing a unique core sequence (5′-ATTTTTAC-3′) in L. gasseri JCM1131T. Interestingly, although the AT-ODN does not contain any CpG sequences, it exerts mitogenic activity in B cells and augments Th-1-type immune responses via Toll-like receptor 9. These findings prompted us to identify strong immunostimulatory non-CpG AT-ODNs that contain the 5′-ATTTTTAC-3′ motif in the genomic sequence of L. gasseri OLL2716. We identified 280 kinds of AT-ODNs in the L. gasseri OLL2716 genome. Mitogenicity and NF-κB gene reporting assays showed that 13 of the 280 AT-ODNs were strongly immunostimulatory when in the TLR9 transfectant. Of these, AT-ODNs LGAT-145 and LGAT-243 were the most potent. With respect to the induction of Th-1-type cytokines, LGAT-243 had the greatest activity and was more potent than the swine prototype, ODN D25. We further found that a six-base secondary loop structure containing a self-stabilized 5′-C…G-3′ stem sequence is important for potent immunostimulatory activity. These results show for the first time that AT-ODNs with a specific loop and stem structure are important factors for immunostimulatory activity. Finally, we found that novel strong immunostimulatory non-CpG AT-ODNs exist in the genome of probiotic lactic acid bacteria.Document Type: Research article
DOI: 10.1111/j.1462-5822.2005.00640.x
Affiliations: 1: Laboratory of Animal Products Chemistry, Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Aoba-ku, Sendai 981-8555, Japan. 2: Food Science Institute, Meiji Dairies Co., 540 Naruda, Odawara, Kanagawa 250-0862, Japan.

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