Recently, we have demonstrated that human detrusor smooth muscle cells in culture secrete the chemokine monocyte chemoattractant protein 1. In the present study, we extended these studies to include the effect of the proinflammatory cytokines tumor necrosis factor (TNF)-⍺ and interleukin (IL)-1β on IL-8, IL-6, and RANTES (regulated on activation, normal T cell expressed and secreted) release by human detrusor smooth muscle cells (HDSMCs) and examined their regulation.

With ethical approval, detrusor muscle biopsies were obtained from patients with benign noninvasive bladder diseases undergoing control cystoscopy. HDSMCs were cultured using an explant technique and used at maximum third passage. HDSMCs were cultured in the presence or absence of TNF-⍺ and IL-1β. Supernatants were collected after 6, 12, and 24 hours. IL-8, IL-6, and RANTES were measured using enzyme-linked immunosorbent assays.

TNF-⍺ and IL-1β (0.01 to 100 ng/mL) induced secretion of IL-8, IL-6, and RANTES in a dose and time-dependent manner. The production of chemokines reached a maximum after 24 hours of incubation. In nonstimulated HDSMCs, the basal secretion of IL-8, IL-6, and RANTES was detectable. Induction of cytokine release by IL-1β was synergistic with TNF-⍺.

These findings for the first time demonstrate that HDSMCs release IL-8, IL-6, and RANTES in response to IL-1β and TNF-⍺. The constitutive and cytokine-stimulated production of chemokines and cytokines suggest that the human detrusor may contribute to mast cell infiltration into the bladder interstitium. The new evidence that HDSMCs secrete immunomodulatory proteins makes the detrusor muscle cell a target for anti-inflammatory therapy.