Effects of protein-energy malnutrition on NF-kappaB signalling in murine peritoneal macrophages.
Protein-energy malnutrition (PEM) is an important public health problem affecting millions of people worldwide. PEM decreases resistance to infection, impairing a number of physiological processes. In unstimulated cells, NF-kappaB is kept from binding to its consensus sequence by the inhibitor I kappaB alpha, which retains NF-kappaB in the cytoplasm. Upon various signals, such as lipopolysaccharide (LPS), I kappaB alpha is rapidly degraded and NF-kappaB is induced to translocate into the nucleus, where it activates expression of various genes that participate in the inflammatory response, including those involved in the synthesis of TNF-alpha. TRAF-6 is a cytoplasmic adapter protein that links the stimulatory signal from Toll like receptor-4 to NF-kappaB. The aim of this study was to evaluate the effect of malnutrition on induction of TNF-alpha by LPS in murine peritoneal macrophages. We evaluated peritoneal cellularity, the expression of MyD88, TRAF-6, IKK, I kappaB alpha and NF-kappaB, NF-kappaB activation and TNF-alpha mRNA and protein synthesis in macrophages. Two-month-old male BALB/C mice were submitted to PEM with a low-protein diet that contained 2% protein, compared to 12% protein in the control diet. When the experimental group had lost about 20% of the original body weight, it was used in the subsequent experiments. Malnourished animals presented anemia, leucopenia and severe reduction in peritoneal cavity cellularity. TNF-alpha mRNA and protein levels of macrophages stimulated with LPS were significantly lower in malnourished animals. PEM also decreased TRAF-6 expression and NF-kappaB activation after LPS stimulation. These results led us to conclude that PEM changes NF-kB signalling pathway in macrophages to LPS stimulus.
Fock
Ricardo Ambrósio
RA
Department of Clinical and Toxicological Analyses, Faculty of Pharmaceutical Sciences, São Paulo University, 05508-900, São Paulo, SP, Brazil. hemato@usp.br
Rogero
Marcelo Macedo
MM
Vinolo
Marco Aurélio Ramirez
MA
Curi
Rui
R
Borges
Maria Carolina
MC
Borelli
Primavera
P
D000740:Anemia / Q000276:immunology / Q000378:metabolism; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D015153:Blotting, Western; D001835:Body Weight; D002478:Cells, Cultured; D018753:Diet, Protein-Restricted; D024202:Electrophoretic Mobility Shift Assay; D051550:I-kappa B Kinase / Q000378:metabolism; D007970:Leukopenia / Q000276:immunology / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology; D017737:Macrophages, Peritoneal / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D053594:Myeloid Differentiation Factor 88 / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism*; D011228:Prealbumin / Q000378:metabolism; D011502:Protein-Energy Malnutrition / Q000209:etiology / Q000276:immunology / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D048029:TNF Receptor-Associated Factor 6 / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism
D008070:Lipopolysaccharides; C507780:Myd88 protein, mouse; D053594:Myeloid Differentiation Factor 88; D016328:NF-kappa B; D011228:Prealbumin; D012333:RNA, Messenger; D048029:TNF Receptor-Associated Factor 6; D014409:Tumor Necrosis Factor-alpha; C482199:lipopolysaccharide, E coli O55-B5; C496564:Chuk protein, mouse; D051550:I-kappa B Kinase