title: Longevity in mice is promoted by probiotic-induced suppression of colonic senescence dependent on upregulation of gut bacterial polyamine production.
abstract: BACKGROUND
  Chronic low-grade inflammation is recognized as an important factor contributing to senescence and age-related diseases. In mammals, levels of polyamines (PAs) decrease during the ageing process; PAs are known to decrease systemic inflammation by inhibiting inflammatory cytokine synthesis in macrophages. Reductions in intestinal luminal PAs levels have been associated with intestinal barrier dysfunction. The probiotic strain Bifidobacterium animalis subsp. lactis LKM512 is known to increase intestinal luminal PA concentrations.
  
  
  RESULTS
  We supplemented the diet of 10-month-old Crj:CD-1 female mice with LKM512 for 11 months, while the controls received no supplementation. Survival rates were compared using Kaplan-Meier survival curves. LKM512-treated mice survived significantly longer than controls (P<0.001); moreover, skin ulcers and tumors were more common in the control mice. We then analyzed inflammatory and intestinal conditions by measuring several markers using HPLC, ELISA, reverse transcription-quantitative PCR, and histological slices. LKM512 mice showed altered 16S rRNA gene expression of several predominant intestinal bacterial groups. The fecal concentrations of PAs, but not of short-chain fatty acids, were significantly higher in LKM512-treated mice (P<0.05). Colonic mucosal function was also better in LKM512 mice, with increased mucus secretion and better maintenance of tight junctions. Changes in gene expression levels were evaluated using the NimbleGen mouse DNA microarray. LKM512 administration also downregulated the expression of ageing-associated and inflammation-associated genes and gene expression levels in 21-month-old LKM512-treated mice resembled those in 10-month-old untreated (younger) mice.
  
  
  CONCLUSIONS
  Our study demonstrated increased longevity in mice following probiotic treatment with LKM512, possibly due to the suppression of chronic low-grade inflammation in the colon induced by higher PA levels. This indicates that ingestion of specific probiotics may be an easy approach for improving intestinal health and increasing lifespan. Further studies are required to clarify its effectiveness in humans.
authors.affiliation: Dairy Science and Technology Institute, Kyodo Milk Industry Co. Ltd., Tokyo, Japan. m-matumoto@meito.co.jp
authors.forename: Mitsuharu
authors.initials: M
authors.lastname: Matsumoto
authors.forename: Shin
authors.initials: S
authors.lastname: Kurihara
authors.forename: Ryoko
authors.initials: R
authors.lastname: Kibe
authors.forename: Hisashi
authors.initials: H
authors.lastname: Ashida
authors.forename: Yoshimi
authors.initials: Y
authors.lastname: Benno
mesh_terms: D000818:Animals; D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000378:metabolism; D001644:Bifidobacterium / Q000502:physiology; D016922:Cellular Senescence / Q000187:drug effects; D003106:Colon / Q000166:cytology / Q000378:metabolism / Q000382:microbiology*; D005243:Feces / Q000737:chemistry / Q000382:microbiology; D005260:Female; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D053208:Kaplan-Meier Estimate; D008136:Longevity / Q000187:drug effects*; D051379:Mice; D008813:Mice, Inbred ICR; D009093:Mucus / Q000378:metabolism; D009369:Neoplasms / Q000517:prevention & control; D020411:Oligonucleotide Array Sequence Analysis; D011073:Polyamines / Q000378:metabolism*; D019936:Probiotics / Q000494:pharmacology*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012883:Skin Ulcer / Q000517:prevention & control; D013096:Spermine / Q000378:metabolism; D019108:Tight Junctions / Q000187:drug effects / Q000378:metabolism / Q000382:microbiology
chemical_list: D011073:Polyamines; D012336:RNA, Ribosomal, 16S; D013096:Spermine