Measurement of in vivo rectal mucosal cytokine and eicosanoid production in ulcerative colitis using filter paper

Background-Excessive mucosal generation of cytokines and eicosanoids has be en reported in vitro in ulcerative colitis (UC) using traumatising biopsy t echniques, and in vivo using time consuming rectal dialysis. Aims-To validate a simple filter paper technique to profile rectal mucosal production of cytokines and eicosanoids in vivo in patients with UC compare d with controls. Patients-Forty one patients with UC (21 with active disease) and 16 control s were studied. Methods-In vitro, recovery of known concentrations of cytokine or mediator applied to filter papers was measured by ELISA following incubation in buff er. In vivo, patients and controls had filter papers apposed to the rectal mucosa briefly through a rigid sigmoidoscope. Filter papers were then incub ated prior to assay by ELISA. Results-In vitro validation studies showed that the filter paper technique could be used to measure mucosal release of interleukin-1 beta (IL-1 beta), tumour necrosis factor alpha (TNF-alpha), thromboxane B-2 (TXB2), and pros taglandin E-2 (PGE(2)), but not interferon gamma (IFN-gamma). Mucosal relea se of IL-1 beta, TNF-alpha, TXB2 and PGE(2) were significantly increased in active uc; (p=0.001) and correlated directly with disease activity (p=0.02 ). Conclusions-The filter paper technique confirmed increased rectal mucosal r elease of cytokines and eicosanoids in UC, in proportion to disease activit y. The simplicity, safety and speed of the technique make it a practicable option for use in the outpatient clinic to study the pathogenesis of inflam matory bowel disease, and potentially its response to treatment.