Marginal dietary zinc deprivation augments sepsis‐induced alterations in skeletal muscle TNF‐α but not protein synthesis

• Published in: Physiological reports 2016-11, Vol.4 (21), p.np-n/a
• Main Authors: Crowell, Kristen T., Kelleher, Shannon L., Soybel, David I., Lang, Charles H.
• Format: Article
• Language: English
• Subjects: Abdomen; Adaptor Proteins, Signal Transducing - metabolism; Animals; Autophagy; Cecum; Cell Cycle Proteins; Chronic illnesses; Cytokines; Diet; Disease Models, Animal; Homeostasis; Illnesses; Immunology; Inflammation; Inflammation - metabolism; Interleukin-6 - metabolism; Kinases; Male; Mice; Mice, Inbred C57BL; mRNA; Muscle Metabolism; Muscle Proteins - biosynthesis; Muscle Proteins - metabolism; muscle wasting; Muscle, Skeletal - anatomy & histology; Muscle, Skeletal - metabolism; Muscular Conditions, Disorders and Treatments; Musculoskeletal system; Nutrient deficiency; Nutrition; Original Research; Peritonitis; Peritonitis - metabolism; Peritonitis - physiopathology; Phosphoproteins - metabolism; Phosphorylation; Proteasomes; Protein Biosynthesis; Protein deficiency; Protein synthesis; Proteins; RNA, Messenger - metabolism; Sepsis; Sepsis - metabolism; Sepsis - physiopathology; Signal transduction; Skeletal Muscle; skeletal muscle metabolism; Studies; TOR protein; TOR Serine-Threonine Kinases - metabolism; Tripartite Motif Proteins - metabolism; Tumor necrosis factor; Tumor Necrosis Factor-alpha - metabolism; Tumor necrosis factor-TNF; Ubiquitin; Ubiquitin-Protein Ligases - metabolism; Wasting Syndrome - metabolism; Zinc; Zinc - deficiency; Zinc - metabolism; Zinc - pharmacology
• ISSN: 2051-817X; 2051-817X
• DOI: 10.14814/phy2.13017

Severe zinc deficiency is associated with an increased systemic inflammatory response and mortality after sepsis. However, the impact of mild zinc deficiency, which is more common in populations with chronic illnesses and sepsis, is unknown. In this study, we hypothesized that marginal dietary Zn deprivation (ZM) would amplify tissue inflammation and exacerbate the sepsis‐induced decrease in muscle protein synthesis. Adult male C57BL/6 mice were fed a zinc‐adequate (ZA) or ZM diet (30 or 10 mg Zn/kg, respectively) over 4 weeks, peritonitis was induced by cecal ligation and puncture (CLP), and mice were examined at either 24 h (acute) or 5 days (chronic) post‐CLP. Acute sepsis decreased the in vivo rate of skeletal muscle protein synthesis and the phosphorylation of the mTOR substrate 4E‐BP1. Acutely, sepsis increased TNF‐α and IL‐6 mRNA in muscle, and the increase in TNF‐α was significantly greater in ZM mice. However, muscle protein synthesis and 4E‐BP1 phosphorylation returned to baseline 5 days post‐CLP in both ZA and ZM mice. Protein degradation via markers of the ubiquitin proteasome pathway was increased in acute sepsis, yet only MuRF1 mRNA was increased in chronic sepsis and ZM amplified this elevation. Our data suggest that mild zinc deficiency increases TNF‐α in muscle acutely after sepsis but does not significantly modulate the rate of muscle protein synthesis. Mild dietary zinc deprivation in male mice exaggerated the increase in skeletal muscle TNF‐α acutely after sepsis. Despite the elevation of this local inflammatory cytokine, the sepsis‐induced decrease in muscle protein synthesis was unchanged with mild zinc deprivation. In the chronic phase of sepsis, zinc deprivation did not affect the normalization of muscle TNF‐α and protein synthesis rate.