Lipopolysaccharide‐induced monocyte chemotactic protein‐1 is enhanced by suppression of nitric oxide production, which depends on poor CD14 expression on the surface of skeletal muscle

Abstract

It is known that lipopolysaccharide (LPS)-induced monocyte chemotactic protein (MCP)-1 secretion from tissues recruits monocytes from the circulation, but the mechanism of the LPS-induced MCP-1 production in skeletal muscle is largely unexplained. To clarify the effect of LPS on MCP-1 production in skeletal muscle cells, C2C12 cells from a mouse skeletal muscle cell line, and RAW 264.7 cells from a mouse macrophage cell line, were used to assess production of LPS-induced MCP-1, nitric oxide (NO) and interferon (IFN)-beta. In addition, we evaluated inducible NO synthases (iNOS) mRNA expression using RT-PCR, and cell surface expression of CD14 and toll-like receptor (TLR) 4 using flow cytometry. In C2C12 cells, LPS stimulation increased MCP-1 production (p < 0.01), but combined treatment with LPS and NO inducer, diethylammonium (Z)-1-(N,N-diethylamino) diazen-1-ium-1,2-diolate (NONOate), significantly inhibited its production (p < 0.01). LPS stimulation neither induced production of NO nor of IFN-beta, which is an NO inducer. Recombinant IFN-beta stimulation, on the other hand, enhanced LPS-induced NO production (p < 0.01). Interestingly, we found that surface expression of CD14, which regulates IFN-beta production, in C2C12 cells was much lower than that in RAW 264.7 cells, although TLR4 expression on C2C12 cells was similar to that on RAW 264.7 cells. These data suggest that the reduced NO production in response to LPS may depend on low expression of CD14 on the cell surface of skeletal muscle, and that it may enhance LPS-induced MCP-1 production. Together, these functions of skeletal muscle could decrease the risk of bacterial infection by recruitment of monocytes.

Cross-talk between skeletal muscle and immune cells: muscle-derived mediators and metabolic implications

“…Peptidoglycan and LPS also elicit expression of the chemokines CCL2 and CXCL1 in C 2 C 12 myotubes, signaled through the NF-B pathway (9,57). Similarly, in vivo, inoculation with low doses of LPS provokes an increase in TNF␣ and IL-6 mRNA in human skeletal muscle (4) and causes CCL2 expression in mouse diaphragm (67).…”

“…TLRs and NLRs are expressed in both myoblasts and mature myotubes, and evidence suggests they play key roles in muscle growth and metabolism (37,144). Stimulation of TLRs induces muscle cell autonomous inflammation and expression of cytokines and chemokines (9,57). Although the effect of whole body ablation of TLR4 on insulin resistance is debated (95,113,132), LPS, presumably acting via TLR4, lowers muscle protein synthesis (69), elevates glucose utilization, decreases fatty acid oxidation (36), and induces oxidative stress and insulin resistance in muscle cells in culture and muscle tissue in vivo (19,30,94,107,152).…”

Effect of Lianshu preparation on lipopolysaccharide-induced diarrhea in rats

“…However, excess NO is probably one of the most important mediators that induce blood poisoning, septic shock and multi-organ dysfunction [10] . When stimulated by LPS, NO is excessively expressed and induces multiorgan functional lesions in stomach and intestine [11][12][13] . In this study, Lianshu preparation prevented enteritis necroticans by inhibiting the production of excess NO.…”

Relationship between macrophage differentiation and the chemotactic activity toward damaged myoblast cells

“…The chemotaxis of LPS-treated macrophages toward C2C12 cells did not increase when the expression of CCR2 on macrophages was not stimulated by the LPS treatment. Some other papers have shown that CCR2 deficient mice exhibited impaired monocyte/macrophage recruitment from blood to injured muscles Lu et al, 2011a), and a delayed recovery of isometric strength of the muscle (Kawanishi et al, 2008). DEX, but not epinephrine (data not shown) increased the CCR2 expression on the membrane surface of macrophages by 140%, and increased the migration toward C2C12 cells.…”

“…Therefore, the killed cell-induced chemokine secretion from the live cells accelerated the migration of macrophages. MCP-1 plays a role not only as a critical mediator of macrophage migration, but also in the regeneration and recovery of the muscle function after injury (Kawanishi et al, 2008). We previously reported that C2C12 cells have a low CD14 expression and a high MCP-1 production via Toll-like receptor 4 (TLR4) (Boyd et al, 2006).…”