title: The activation of the TLR2/p38 pathway by sodium butyrate in bovine mammary epithelial cells is involved in the reduction of Staphylococcus aureus internalization.
abstract: Staphylococcus aureus is an etiological agent of human and animal diseases, and it is able to internalize into non-professional phagocytic cells (i.e. bovine mammary epithelial cells, bMECs), which is an event that is related to chronic and recurrent infections. bMECs contribute to host innate immune responses (IIR) through TLR pathogen recognition, whereby TLR2 is the most relevant for S. aureus. In a previous report, we showed that sodium butyrate (NaB, 0.5mM), which is a short chain fatty acid (SCFA), reduced S. aureus internalization into bMECs by modulating their IIR. However, the molecular mechanism of this process has not been described, which was the aim of this study. The results showed that the TLR2 membrane abundance (MA) and mRNA expression were induced by 0.5mM NaB ∼1.6-fold and ∼1.7-fold, respectively. Additionally, 0.5mM NaB induced p38 phosphorylation, but not JNK1/2 or ERK1/2 phosphorylation in bMECs, which reached the baseline when the bMECs were S. aureus-challenged. Additionally, bMECs that were treated with 0.5mM NaB (24h) showed activation of 8 transcriptional factors (AP-1, E2F-1, FAST-1, MEF-1, EGR, PPAR, ER and CBF), which were partially reverted when the bMECs were S. aureus-challenged. Additionally, 0.5mM NaB (24h) up-regulated mRNA expression of the antimicrobial peptides, TAP (∼4.8-fold), BNBD5 (∼3.2-fold) and BNBD10 (∼2.6-fold). Notably, NaB-treated and S. aureus-challenged bMECs increased the mRNA expression of all of the antimicrobial peptides that were evaluated, and this was evident for LAP and BNBD5. In the NaB-treated bMECs, we did not detect significant expression changes for IL-1β and IL-6 and only TNF-α, IL-10 and IL-8 were induced. Interestingly, the NaB-treated and S. aureus-challenged bMECs maintained the anti-inflammatory response that was induced by this SCFA. In conclusion, our results suggest that 0.5mM NaB activates bMECs via TLR2/p38, which leads to improved antimicrobial defense before/after pathogen invasion, and NaB may exert anti-inflammatory effects during infection.
authors.affiliation: Centro Multidisciplinario de Estudios en Biotecnología, Facultad de Medicina Veterinaria y Zootecnia, Universidad Michoacana de San Nicolás de Hidalgo, Km 9.5 Carr, Morelia-Zinapécuaro, Posta Veterinaria, C.P. 58893 Morelia, Michoacán, Mexico.
authors.forename: Nayeli
authors.initials: N
authors.lastname: Alva-Murillo
authors.affiliation: Centro Multidisciplinario de Estudios en Biotecnología, Facultad de Medicina Veterinaria y Zootecnia, Universidad Michoacana de San Nicolás de Hidalgo, Km 9.5 Carr, Morelia-Zinapécuaro, Posta Veterinaria, C.P. 58893 Morelia, Michoacán, Mexico.
authors.forename: Ivan
authors.initials: I
authors.lastname: Medina-Estrada
authors.affiliation: Centro Multidisciplinario de Estudios en Biotecnología, Facultad de Medicina Veterinaria y Zootecnia, Universidad Michoacana de San Nicolás de Hidalgo, Km 9.5 Carr, Morelia-Zinapécuaro, Posta Veterinaria, C.P. 58893 Morelia, Michoacán, Mexico.
authors.forename: Marisol
authors.initials: M
authors.lastname: Báez-Magaña
authors.affiliation: Centro Multidisciplinario de Estudios en Biotecnología, Facultad de Medicina Veterinaria y Zootecnia, Universidad Michoacana de San Nicolás de Hidalgo, Km 9.5 Carr, Morelia-Zinapécuaro, Posta Veterinaria, C.P. 58893 Morelia, Michoacán, Mexico.
authors.forename: Alejandra
authors.initials: A
authors.lastname: Ochoa-Zarzosa
authors.affiliation: Centro Multidisciplinario de Estudios en Biotecnología, Facultad de Medicina Veterinaria y Zootecnia, Universidad Michoacana de San Nicolás de Hidalgo, Km 9.5 Carr, Morelia-Zinapécuaro, Posta Veterinaria, C.P. 58893 Morelia, Michoacán, Mexico. Electronic address: elmeza@umich.mx.
authors.forename: Joel E
authors.initials: JE
authors.lastname: López-Meza
mesh_terms: D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology; D023181:Antimicrobial Cationic Peptides / Q000096:biosynthesis / Q000235:genetics; D001692:Biological Transport / Q000187:drug effects; D020148:Butyric Acid / Q000494:pharmacology*; D018955:CD36 Antigens / Q000378:metabolism; D002417:Cattle; D002478:Cells, Cultured; D004789:Enzyme Activation / Q000187:drug effects; D004847:Epithelial Cells / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005260:Female; D016753:Interleukin-10 / Q000096:biosynthesis; D053583:Interleukin-1beta / Q000096:biosynthesis; D015850:Interleukin-6 / Q000096:biosynthesis; D016209:Interleukin-8 / Q000096:biosynthesis; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D008321:Mammary Glands, Animal / Q000166:cytology / Q000378:metabolism / Q000382:microbiology*; D009842:Oligopeptides / Q000096:biosynthesis / Q000235:genetics; D010766:Phosphorylation; D012333:RNA, Messenger / Q000096:biosynthesis; D013203:Staphylococcal Infections / Q000188:drug therapy*; D013211:Staphylococcus aureus / Q000187:drug effects*; D051195:Toll-Like Receptor 2 / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis; D023083:beta-Defensins / Q000096:biosynthesis / Q000235:genetics; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
chemical_list: D000893:Anti-Inflammatory Agents; D023181:Antimicrobial Cationic Peptides; D018955:CD36 Antigens; C556062:IL10 protein, mouse; C587672:IL1B protein, mouse; D053583:Interleukin-1beta; D015850:Interleukin-6; D016209:Interleukin-8; D009842:Oligopeptides; D012333:RNA, Messenger; D051195:Toll-Like Receptor 2; D014157:Transcription Factors; D014409:Tumor Necrosis Factor-alpha; D023083:beta-Defensins; C080396:trypsinogen activation peptide; D020148:Butyric Acid; D016753:Interleukin-10; D048049:Extracellular Signal-Regulated MAP Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases
keywords: Butyrate; Epithelial cells; Internalization; Staphylococcus aureus; TLR2; p38