Effect of Intravenous Immuoglobulin on Interleukin-6 Production in Human Skeletal Muscle Cell Line (HM4)

BACKGROUND: Intravenous immunoglobulin (IVIg) has been widely used in the management of patients with various autoimmune neurological diseases, however, its action mechanisms have not fully been elucidated yet. This study focused on the effects of IVIg on the production of interleukin-6 (IL-6), one of major proinflammatory cytokine, using a human skeletal muscle cell line (HM4). METHODS: After HM4 cells were cultured in Dulbecco's modified eagle's medium (DMEM) containing 5% fetal bovine serum for 24 h, the culture medium was changed with serum-free media. TNF-alpha (tumor necrosis factor-alpha, 100 ng/mL) and IVIg (5 mg/mL) were treated alone or in combination and cultured for various time. RT-PCR and ELISA kit were employed for mRNA expression and secretion of IL-6, respectively. RESULTS: Treatment with TNF-alpha or/and IVIg significantly induced IL-6 mRNA expression (p<0.001). Although IL-6 production was markedly increased by TNF-alpha (p<0.001), IVIg treatment alone or in combination with TNF-alpha had no effect on the production of IL-6 except at 6 h after the treatment. CONCLUSIONS: IVIg seems not to have a significant effect on IL-6 production as an action mechanism of its immunomodulatory capabilities, at least in the HM4 cell line.

The Expression of Cytokines and Chemokine mRNA by Human Skeletal Muscle Cell Line (SKM14)

BACKGROUND: Muscle is a target of immunological injury in several muscle diseases, such as idiopathic inflammatory myopathy. However, it is also a target for gene therapy. Therefore, it is important to understand the immunological capabilities of muscle cells. To assess as to whether muscle cells are actively involved in the inflamed muscle tissue, a human skeletal muscle cell line was tested for the expression of several cytokines and chemokine at the mRNA level. METHODS: A human skeletal muscle cell line (SKM14) had been developed by a retroviral vector encoding v-myc transfection into a 12-week-old human fetal skeletal muscle tissue characterized by the immunostaining of several musclespecific markers. Human skeletal myoblasts of this cell line were tested for their capacity to express different cytokines (IL-1beta, -6, -10, -12, -15, and TNF-alpha) and chemokine (IL-8) mRNA levels at the basal state and in the presence of TNF-alpha(10 ng/ml). RESULTS: The SKM14 cell line was confirmed to be able to express various cytokines constitutively (IL-6, -8, -12, -15, and TNF-alpha) and in the presence of TNF-alpha(IL-1beta, -6, -8, -10, -12, -15, and TNF-alpha). CONCLUSIONS: Our results suggest that muscle cells may play a role as immunocompetent cells.