Interleukin-6 expression and regulation in rat enteric glial cells

As yet, little is known about the function of the glia of the enteric nervous system (ENS), particularly in an immune-stimulated environment. This prompted us to study the potential of cultured enteroglial cells for cytokine synthesis and secretion. Jejunal myenteric plexus preparations from adult rats were enzymatically dissociated, and enteroglial cells were purified by complement-mediated cytolysis and grown in tissue culture. Cultured cells were stimulated with recombinant rat interleukin (IL)-1 beta, IL-6, and tumor necrosis factor (TNF)-alpha, and IL-6 mRNA expression and secretion were assessed using RT-PCR and a bioassay, respectively. Stimulation with TNF-alpha did not affect IL-6 mRNA expression, whereas IL-1 beta stimulated IL-6 mRNA and protein synthesis in a time- and concentration-dependent fashion. In contrast, IL-6 significantly and dose-dependently suppressed IL-6 mRNA expression. In summary, we have presented evidence that enteric glial cells are a potential source of IL-6 in the myenteric plexus and that cytokine production by enteric glial cells can be regulated by cytokines. These findings strongly support the contention that enteric glial cells act as immunomodulatory cells in the enteric nervous system.