Genomic Characterization and Safety Assessment of Bifidobacterium breve BS2-PB3 as Functional Food.

Our group had isolated Bifidobacterium breve strain BS2-PB3 from human breast milk. In this study, we sequenced the whole genome of B. breve BS2-PB3, and with a focus on its safety profile, various probiotic characteristics (presence of antibiotic resistance genes, virulence factors, and mobile elements) were then determined through bioinformatic analyses. The antibiotic resistance profile of B. breve BS2-PB3 was also evaluated. The whole genome of B. breve BS2-PB3 consisted of 2,268,931 base pairs with a G-C content of 58.89% and 2,108 coding regions. The average nucleotide identity and whole-genome phylogenetic analyses supported the classification of B. breve BS2-PB3. According to our in silico assessment, B. breve BS2-PB3 possesses antioxidant and immunomodulation properties in addition to various genes related to the probiotic properties of heat, cold, and acid stress, bile tolerance, and adhesion. Antibiotic susceptibility was evaluated using the Kirby-Bauer disk-diffusion test, in which the minimum inhibitory concentrations for selected antibiotics were subsequently tested using the Epsilometer test. B. breve BS2-PB3 only exhibited selected resistance phenotypes, i.e., to mupirocin (minimum inhibitory concentration/MIC >1,024 µg/ml), sulfamethoxazole (MIC >1,024 µg/ml), and oxacillin (MIC >3 µg/ml). The resistance genes against those antibiotics, i.e., ileS, mupB, sul4, mecC and ramA, were detected within its genome as well. While no virulence factor was detected, four insertion sequences were identified within the genome but were located away from the identified antibiotic resistance genes. In conclusion, B. breve BS2-PB3 demonstrated a sufficient safety profile, making it a promising candidate for further development as a potential functional food.

Molecular Basis and Role of Siglec-7 Ligand Expression on Chronic Lymphocytic Leukemia B Cells.

Siglec-7 (sialic acid-binding immunoglobulin-like lectin 7) is an immune checkpoint-like glycan recognition protein on natural killer (NK) cells. Cancer cells often upregulate Siglec ligands to subvert immunosurveillance, but the molecular basis of Siglec ligands has been elusive. In this study, we investigated Siglec-7 ligands on chronic lymphocytic leukemia (CLL) B cells. CLL B cells express higher levels of Siglec-7 ligands compared with healthy donor B cells, and enzymatic removal of sialic acids or sialomucins makes them more sensitive to NK cell cytotoxicity. Gene knockout experiments have revealed that the sialyltransferase ST6GalNAc-IV is responsible for the biosynthesis of disialyl-T (Neu5Acα2-3Galß1-3[Neu5Acα2-6]GalNAcα1-), which is the glycotope recognized by Siglec-7, and that CD162 and CD45 are the major carriers of this glycotope on CLL B cells. Analysis of public transcriptomic datasets indicated that the low expression of GCNT1 (encoding core 2 GlcNAc transferase, an enzyme that competes against ST6GalNAc-IV) and high expression of ST6GALNAC4 (encoding ST6GalNAc-IV) in CLL B cells, together enhancing the expression of the disialyl-T glycotope, are associated with poor patient prognosis. Taken together, our results determined the molecular basis of Siglec-7 ligand overexpression that protects CLL B cells from NK cell cytotoxicity and identified disialyl-T as a potential prognostic marker of CLL.

Anti-Inflammatory and Anticancer Activities of Taiwanese Purple-Fleshed Sweet Potatoes (Ipomoea batatas L. Lam) Extracts.

Purple-fleshed sweet potato (PFSP) (Ipomoea batatas L. Lam) has been known to possess high amount of anthocyanins which contribute to its antioxidant activity. However, a few reports are available concerning its anti-inflammatory and anticancer properties. In this study, PFSP "Tainung 73," which is locally grown in Taiwan, was steamed and extracted using acidified ethanol pH 3.5 under 80°C. Two kinds of crude anthocyanins extracts were obtained, namely, SP (Steamed, Peeled) and SNP (Steamed, No Peeled). Then, anti-inflammatory and anticancer activities of these extracts were investigated. Cell viability assay (MTT) showed that SP and SNP extracts were not toxic to RAW 264.7 cells. They even exhibited anti-inflammatory activities by suppressing the production of NO and proinflammatory cytokines, such as NF-κß, TNF-α, and IL-6, in LPS-induced macrophage cells. Anticancer activities of these extracts were displayed through their ability to inhibit the growth of cancer cell lines, such as MCF-7 (breast cancer), SNU-1 (gastric cancer), and WiDr (colon adenocarcinoma), in concentration- and time-dependent manner. Further studies also revealed that SP extracts could induce apoptosis in MCF-7 and SNU-1 cancer cells through extrinsic and intrinsic pathway. In the future, PSFP extracts may have potential to be applied in nutraceutical, pharmaceutical, and food industries.