title: Protective effects of leucine against lipopolysaccharide-induced inflammatory response in Labeo rohita fingerlings.
abstract: The present study investigated the protective effects of leucine against lipopolysaccharide (LPS)-induced inflammatory responses in Labeo rohita (rohu) in vivo and in vitro. Primary hepatocytes, isolated from the hepatopancreas, were exposed to different concentrations of LPS for 24 h to induce an inflammatory response, and the protective effects of leucine against LPS-induced inflammation were studied. Finally, we investigated the efficiency of dietary leucine supplementation in attenuating an immune challenge induced by LPS in vivo. Exposure of cells to 10-25 μg mL(-1) of LPS for 24 h resulted in a significant production of nitric oxide and release of lactate dehydrogenase to the medium, whereas cell viability and protein content were reduced (p < 0.05). LPS exposure (10 μg mL(-1)) increased mRNA levels of the pro-inflammatory cytokines TNF-α, IL-1β and IL-8 in vitro (p < 0.05). However, pretreatment with leucine prevented the LPS-induced upregulation of TNF-α, IL-1β and IL-8 mRNAs by downregulating TLR4, MyD88, NF-κBp65, and MAPKp38 mRNA expression. Interestingly, mRNA expression of the anti-inflammatory cytokine, IL-10, which was increased by LPS treatment, was further enhanced (p < 0.05) by leucine pretreatment. The enhanced expression of IL-10 might inhibit the production of other pro-inflammatory cytokines. It was found that leucine pretreatment attenuated the excessive activation of LPS-induced TLR4-MyD88 signaling as manifested by lower level of TLR4, MyD88, MAPKp38, NF-κBp65 and increased level of IκB-α protein in leucine pre-treatment group. In vivo experiments demonstrated that leucine pre-supplementation could protect fish against LPS-induced inflammation through an attenuation of TLR4-MyD88 signaling pathway. Taken together, we propose that leucine pre-supplementation decreases LPS-induced immune damage in rohu by enhancing the expression of IL-10 and by regulating the TLR4-MyD88 signaling pathways.
authors.affiliation: Lab of Aquatic Biomedicine, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Gwanak-ro, Seoul, South Korea. Electronic address: giribiotek@gmail.com.
authors.forename: Sib Sankar
authors.initials: SS
authors.lastname: Giri
authors.affiliation: School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India. Electronic address: shibsankar.iicb@gmail.com.
authors.forename: Shib Sankar
authors.initials: SS
authors.lastname: Sen
authors.affiliation: Lab of Aquatic Biomedicine, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Gwanak-ro, Seoul, South Korea. Electronic address: advancewoo@snu.ac.kr.
authors.forename: Jin Woo
authors.initials: JW
authors.lastname: Jun
authors.affiliation: Dept. of Biotechnology, Periyar Maniammai University, Thanjavur, Tamil Nadu, India. Electronic address: drvsukumar@gmail.com.
authors.forename: Venkatachalam
authors.initials: V
authors.lastname: Sukumaran
authors.affiliation: Lab of Aquatic Biomedicine, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Gwanak-ro, Seoul, South Korea. Electronic address: parksec@snu.ac.kr.
authors.forename: Se Chang
authors.initials: SC
authors.lastname: Park
mesh_terms: D000821:Animal Feed / Q000032:analysis; D000818:Animals; D003530:Cyprinidae / Q000276:immunology*; D004032:Diet / Q000662:veterinary; D019587:Dietary Supplements; D005393:Fish Diseases / Q000276:immunology*; D022781:Hepatocytes / Q000187:drug effects / Q000276:immunology; D007249:Inflammation / Q000276:immunology / Q000662:veterinary*; D007930:Leucine / Q000008:administration & dosage / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D008070:Lipopolysaccharides; D007930:Leucine
keywords: Hepatocyte; IL-10; Labeo rohita; Leucine; Lipopolysaccharide; TLR4 signaling