The effects of protein malnutrition on the TNF-RI and NF-jB expression via the TNF-a signaling pathway Dalila Cunha de Oliveira, Araceli Aparecida Hastreiter, Alexandra Siqueira Mello, Jackeline Soares de Oliveira Beltran, Ed Wilson Cavalcante Oliveira Santos, Primavera Borelli, Ricardo Ambrósio Fock ⇑ School of Pharmaceutical Sciences, Department of Clinical and Toxicological Analyses, University of Sao Paulo, Brazil article info Article history: Received 6 February 2014 Received in revised form 9 April 2014 Accepted 4 June 2014 Keywords: Malnutrition Macrophages TNF-a TNF-RI NF-jB abstract Malnutrition is a nutritional condition that can affect many aspects of the immunological response, including by decreasing cell migration and stimulating phagocytosis; the bactericidal response; changes in reactive oxygen and nitrogen species production; and the production of proinflammatory cytokines, such as tumor necrosis factor alpha (TNF-a). This cytokine is primarily produced by macrophages and is associated with a wide range of biological activities, including inflammatory processes, growth, differ- entiation, and apoptosis. TNF-a acts through the activation of TNF receptors, and mainly receptor I (TNF- RI), which is responsible for most of the effects of TNF-a. This activation triggers a series of intracellular events that result in the activation of the transcription factor NF-jB. In this study, we evaluated the expression of the transcription factor NF-jB, mediated by TNF-a through TNF-RI, in a protein malnutri- tion (PM) model. Adult male BALB/c mice were submitted to PM, and after loss of approximately 20% of their body weight, their peritoneal macrophages were collected and cultivated with or without TNF-a. The expression of TNF-RI and proteins in its signaling pathway (TRADD, TRAF, RIP, IKK, IKB-a, pIKB-a, NF-jB, and pNF-jB) were evaluated, as well as cytokine production (IL-1a, IL-1b, IL-6, and IL-12). The compiled results highlight that the malnourished animals presented anemia, leukopenia, and decreased peritoneal cellularity. TNF-RI expression was reduced in the malnourished animals, and NF-jB phosphorylation was also reduced, in association with reduced production of IL-1b and IL-12. In this study, we observed aspects related to the innate immune response, and the outcome data allowed us to conclude that nutritional status interferes with the macrophage activation and the response capabilities of these cells. Ó 2014 Elsevier Ltd. All rights reserved. 1. Introduction Despite numerous advances and improvements in health, mal- nutrition remains one of the major global health challenges in many low-income countries, with high rates of associated mortal- ity and morbidity [1]. Protein malnutrition (PM) results in patho- logical changes that predispose individuals to infections, increasing morbidity and mortality rates [2,3]. Innate immunity is the first barrier against infections and plays a pivotal role in the induction of adaptive immunity [4]. Macrophages are involved in innate immunity, with the ability to phagocytize and kill fungi and other microorganisms, and lead to the secretion of a number of proinflammatory cytokines, such as interleukin 1 (IL-1), interleukin 6 (IL-6), and tumor necrosis factor alpha (TNF-a). The upregulation of these cytokines is an important mechanism of host defense against infection [5,6]. However, the exact mechanisms that modulate the immune sys- tem under conditions of malnutrition are still not fully understood. TNF-a is one of the most prominent inflammatory mediators. This cytokine is produced by macrophages and is central in starting inflammatory reactions of the innate immune system, including the induction of cytokine production, the activation and expression of adhesion molecules, and growth stimulation. These effects are mediated by the activation of TNF receptors, and mainly receptor I (TNF-RI), which is responsible for most of the effects of TNF-a and which triggers a series of intracellular events that result in activation of the pathway of the transcription factor NF-jB [7–9]. Upon activation of TNF-RI at the cellular membrane, adapter molecules are primarily recruited, including TNFR-associated http://dx.doi.org/10.1016/j.cyto.2014.06.004 1043-4666/Ó 2014 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. Address: Experimental Hematology Laboratory, Depart- ment of Clinical and Toxicological Analyses, School of Pharmaceutical Sciences, University of Sao Paulo, Avenida Lineu Prestes, 580 Bloco 17, Sao Paulo, SP 05508- 900, Brazil. Tel.: +55 11 3091 3639. E-mail address: hemato@usp.br (R.A. Fock). Cytokine 69 (2014) 218–225 Contents lists available at ScienceDirect Cytokine journal homepage: www.journals.elsevier.com/cytokine