Anti-inflammatory effects of bromelain in lps-induced human U937 macrophages

Bromelain, a natural product from pineapple, is known for its anti-inflammatory and immunomodulatory activities. However, there was limited evidence to demonstrate bromelain effects on chemokines. Here, we aim to investigate the effects of bromelain on the expression of chemokines induced by lipopolysaccharide (LPS) on human U937 macrophages. Expression of chemokine, cytokine and cyclooxygenase-2 (COX-2) messenger RNAs (mRNAs) in LPS-stimulated macrophages in the absence or presence of bromelain was determined by real time polymerase chain reaction (PCR). Cytotoxicity was evaluated by 3-[4,5-dimethylthiazol- 2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assays. Co-treatment of LPS and bromelain at 100 μg/mL exhibited inhibitory effects on the expression of the proinflammatory genes including macrophage inflammatory protein-1alpha (MIP-1α) (P < 0.05), macrophage inflammatory protein-1beta (MIP-1α) (P < 0.01), monocyte chemoattractant protein-1 (MCP- 1) (P < 0.01), interleukin-8 (IL-8) (P < 0.05), interleukin-1beta (IL-1β) (P < 0.05), interleukin- 6 (IL-6) (P < 0.01) and COX-2 (P < 0.05) when compared to LPS exposure. Bromelain showed anti-inflammation effects in macrophages by suppressing pro-inflammatory cytokines, chemokines and the cyclooxygenase pathway. Accordingly, these effects may be therapeutically useful for the treatment of inflammatory diseases.