title: Lactobacillus acidophilus attenuates Salmonella-induced intestinal inflammation via TGF-β signaling.
abstract: BACKGROUND
  Salmonella is a common intestinal pathogen that causes acute and chronic inflammatory response. Probiotics reduce inflammatory cytokine production and serve as beneficial commensal microorganisms in the human gastrointestinal tract. TGF-β (transforming growth factor β)/SMAD and NF-κB signaling play important roles in inflammation in intestinal cells. However, the involvement of the signaling in regulating inflammation between Salmonella and probiotics is not fully understood.
  
  
  METHODS
  L. acidophilus and prebiotic inulin were used to treat human intestinal Caco-2 cells prior to infection with Salmonella. The cells were harvested to examine the cytokines and MIR21 expression with immunoblotting and real-time PCR. NF-κB and SMAD3/4 reporter vectors were transfected into cells to monitor inflammation and TGF-β1 signaling, respectively.
  
  
  RESULTS
  In this study, we showed that the probiotic L. acidophilus decreased Salmonella-induced NF-κB activation in human intestinal Caco-2 cells. Expression of the inflammatory cytokines, TNF-α and IL-8, in L. acidophilus-pretreated cells was also significantly lower than that in cells infected with Salmonella alone. Moreover, TGF-β1 and MIR21 expression was elevated in cells pretreated with L. acidophilus or synbiotic, a combination of inulin and L. acidophilus, compared to that in untreated cells or cells infected with S. typhimurium alone. By contrast, expression of SMAD7, a target of MIR21, was accordingly reduced in cells treated with L. acidophilus or synbiotics. Consistent with TGF-β1/MIR21 and SMAD7 expression, SMAD3/4 transcriptional activity was significantly higher in the cells treated with L. acidophilus or synbiotics. Furthermore, TGF-β1 antibody antagonized the SMAD3/4 and NF-κB transcriptional activity modulated by L. acidophilus in intestinal cells.
  
  
  CONCLUSIONS
  Our results suggest that the TGF-β1/MIR21 signaling pathway may be involved in the suppressive effects of L. acidophilus on inflammation caused by S. typhimurium in intestinal Caco-2 cells.
authors.affiliation: Department of Pediatrics, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan. huang.ifei@yahoo.com.|Faculty of Medicine, National Yang-Ming University, Taipei, Taiwan. huang.ifei@yahoo.com.|Chung Hwa University of Medical Technology, Tainan, Taiwan. huang.ifei@yahoo.com.
authors.forename: I-Fei
authors.initials: IF
authors.lastname: Huang
authors.affiliation: Diet and Nutrition Section, Zuoying Branch of Kaohsiung Armed Forces General Hospital, Kaohsiung, Taiwan. Diet0523@gmail.com.
authors.forename: I-Chun
authors.initials: IC
authors.lastname: Lin
authors.affiliation: Department of Medical Education and Research, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan. d908203@gmail.com.
authors.forename: Pei-Feng
authors.initials: PF
authors.lastname: Liu
authors.affiliation: Department of Pediatrics, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan. mfcheng@vghks.gov.tw.|Faculty of Medicine, National Yang-Ming University, Taipei, Taiwan. mfcheng@vghks.gov.tw.
authors.forename: Ming-Fang
authors.initials: MF
authors.lastname: Cheng
authors.affiliation: Department of Medical Education and Research, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan. oyster0@hotmail.com.
authors.forename: Yen-Chen
authors.initials: YC
authors.lastname: Liu
authors.affiliation: Department of Dentistry, Kaohsiung Veterans General Hospital, Pingtung, Taiwan. mrusmrus@gmail.com.
authors.forename: Yao-Dung
authors.initials: YD
authors.lastname: Hsieh
authors.affiliation: Department of Pharmacy, Tajen University, Pingtung, Taiwan. jjchen@mail.tajen.edu.tw.
authors.forename: Jih-Jung
authors.initials: JJ
authors.lastname: Chen
authors.affiliation: Department of Biological Science, National Sun Yat-sen University, Kaohsiung, Taiwan. chunlinchen@mail.nsysu.edu.tw.|Doctoral Degree Program in Marine Biotechnology, National Sun Yat-sen University and Academia Sinica, Kaohsiung, Taiwan. chunlinchen@mail.nsysu.edu.tw.
authors.forename: Chun-Lin
authors.initials: CL
authors.lastname: Chen
authors.affiliation: Department of Biomedical Science and Environmental Biology, Kaohsiung Medical University, Kaohsiung, Taiwan. changhw2007@gmail.com.|Research Center of Environmental Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan. changhw2007@gmail.com.
authors.forename: Hsueh-Wei
authors.initials: HW
authors.lastname: Chang
authors.affiliation: Department of Medical Education and Research, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan. cwshu@vghks.gov.tw.
authors.forename: Chih-Wen
authors.initials: CW
authors.lastname: Shu
mesh_terms: D018938:Caco-2 Cells; D016207:Cytokines / Q000096:biosynthesis; D020869:Gene Expression Profiling; D006801:Humans; D007166:Immunosuppressive Agents; D007249:Inflammation / Q000473:pathology*; D007444:Inulin / Q000378:metabolism; D007779:Lactobacillus acidophilus / Q000254:growth & development*; D008954:Models, Biological; D016328:NF-kappa B / Q000378:metabolism; D019936:Probiotics; D060888:Real-Time Polymerase Chain Reaction; D012480:Salmonella Infections / Q000473:pathology*; D015398:Signal Transduction; D051900:Smad3 Protein / Q000096:biosynthesis; D051901:Smad4 Protein / Q000096:biosynthesis; D016212:Transforming Growth Factor beta / Q000378:metabolism*
chemical_list: D016207:Cytokines; D007166:Immunosuppressive Agents; D016328:NF-kappa B; C497790:SMAD3 protein, human; C497796:SMAD4 protein, human; D051900:Smad3 Protein; D051901:Smad4 Protein; D016212:Transforming Growth Factor beta; D007444:Inulin