IL-1β stimulates IL-6 production in cultured skeletal muscle cells through activation of MAP kinase signaling pathway and NF-κB

Abstract

Recent studies suggest that the skeletal muscle may be a significant site of IL-6 production in various conditions, including exercise, inflammation, hypoperfusion, denervation, and local muscle injury. The mediators and molecular mechanisms regulating muscle IL-6 production are poorly understood. We tested the hypothesis that IL-6 production in muscle cells is regulated by IL-1beta and that mitogen-activated protein (MAP) kinase signaling and NF-kappaB activation are involved in IL-1beta-induced IL-6 production. Cultured C2C12 cells, a mouse skeletal muscle cell line, were treated with different concentrations (0.1-2 ng/ml) of IL-1beta in the absence or presence of the p38 MAP kinase inhibitor SB-208350 or the p42/44 inhibitor PD-98059. Protein and gene expression of IL-6 were determined by ELISA and real-time PCR, respectively. NF-kappaB DNA binding activity was determined by electrophoretic mobility shift assay and by transfecting myocytes with a luciferase reporter plasmid containing a promoter construct with multiple repeats of NF-kappaB binding site. Treatment of myotubes with IL-1beta resulted in a dose- and time-dependent increase of IL-6 production accompanied by an approximately 25-fold increase in IL-6 mRNA levels. IL-1beta stimulated NF-kappaB DNA binding activity and gene activation. SB-208350 and PD-98059 inhibited the increase in IL-6 production induced by IL-1beta. The present results support the concept that skeletal muscle is an important site of IL-6 production. In addition, the results suggest the IL-1beta regulates muscle IL-6 production at least in part by activating the MAP kinase pathway and NF-kappaB.

Interleukin-1β stimulates early myogenesis of mouse C2C12 myoblasts: the impact on myogenic regulatory factors, extracellular matrix components, IGF binding proteins and protein kinases

“…Both plasma IL-1β and hindlimb muscle ubiquitin-proteasome pathway were elevated in tumor-bearing and cachectic mice (Cannon et al 2008). According to in vivo (Cai et al 2004) and in vitro studies (Luo et al 2003, Chevrel et al 2005 IL-1β activated p38 MAPK and NF-kB: the signaling elements that promote the proteolysis in muscle and the reduction of myofibrillar proteins (Li et al 2009). …”

Plasma cytokine response, lipid peroxidation and NF-κB activation in skeletal muscle following maximum progressive swimming

“…NF-κB activation involves the phosphorylation and subsequent proteolytic degradation of the inhibitory protein IκB, a process mediated by specific IκB kinases. Free NF-κB (typically, a heterodimer of p50 and p65) then passes into the nucleus, where it binds to κB sites in the promoter regions of many genes, including those coding for cytokines, antioxidant enzymes, inducible nitric oxide synthase and adhesion molecules (8)(9)(10). Many signals are responsible for NF-κB activation in a variety of cells and tissues, including ROS (11)(12)(13).…”

“…This change may account for the anti-inflammatory effect of exercise (19,20). Evidence suggests that NF-κB activation is responsible for the control of cytokine secretion mediated by contractile muscle (9).…”

Immune Suppression and Inflammation in the Progression of Breast Cancer

“…A potential candidate is interleukin 6 (IL-6), since IL-1β leads to the production of IL-6 (19), and the levels of IL-6 in the tumor microenvironment are reduced in IL-1R -/-mice. To determine if MDSC can interact directly with IL-6, the expression of the IL-6R on MDSC was evaluated by flow cytometry (Figure 2).…”