Effect of cholecystokinin octapeptide on tumor necrosis factor α transcription and nuclear factor-κB activity induced by lipopolysaccharide in rat pulmonary interstitial macrophages

AIM: To elucidate the anti-inflammatory mechanism of an intestinal neuropeptide, sulfated cholecystokinin octapeptide (sCCK-8), the effects of sCCK-8 on lipopolysaccharide (LPS)-induced tumor necrosis factor α (TNF-α) mRNA expression and NF-κB activity in pulmonary interstitial macrophages (PIMs) were studied. METHODS: PIMs from rat were stimulated with LPS (1 mg·L-1) in the presence or absence of sCCK-8 (10-8 - 10-6 mol·L-1) or/and CCK receptor antagonist proglumide (2 mg·L-1). The expression of TNF-α mRNA was assayed by reverse transcription polymerase chain reaction (RT-PCR) at 3 h of the stimulation, and nuclear factor-κB (NF-κB) binding activity was analyzed by electrophoretic mobility shift assay (EMSA) at 1 h of stimulation. The IκB-α protein level in the cytoplasma at 30 min of the stimulation was detected by Western blot. RESULTS: sCCK-8, at concentrations from 10-8 mol·L-1 to 10-6 mol·L-1 obviously inhibited LPS-induced TNF-α mRNA expression and NF-κB binding activity in a dose-dependent manner, P < 0.05, P < 0.01. Stimulation PIMs with LPS resulted in a reduction of IκB-α protein level, P < 0.01, which was elevated by sCCK-8, P < 0.05. The effects of sCCK-8 on NF-κB activity and IκB protein level were attenuated by CCK receptor antagonist proglumide, P < 0.01. CONCLUSION: sCCK-8 inhibits LPS-induced TNF-α mRNA expression by regulating NF-κB activity in rat PIMs, which is mediated through CCK receptors and inhibiting IκB-α degradation. This represents one of the anti-inflammatory mechanisms of sCCK-8.