Lactic acid bacterium, Lactobacillus paracasei KW3110, suppresses inflammatory stress-induced caspase-1 activation by promoting interleukin-10 production in mouse and human immune cells.

A strain of lactic acid bacteria, Lactobacillus paracasei KW3110 (KW3110), activates M2 macrophages with anti-inflammatory reactions and mitigates aging-related chronic inflammation and blue-light exposure-induced retinal inflammation in mice. However, the mechanism underlying the anti-inflammatory effects of KW3110 remains unclear. In this study, we investigated the anti-inflammatory effects of KW3110 using both mouse and human immune cells and evaluated the suppressive effect of KW3110 on the inflammatory reactions of the cells stimulated with lipopolysaccharide and adenosine 5'-triphosphate (LPS/ATP). KW3110 treatment induced anti-inflammatory cytokine interleukin (IL)-10 production in the supernatants of murine macrophage-like cells, J774A.1, and suppressed IL-1β production in the supernatants of LPS/ATP-stimulated cells. The influence of KW3110 on the production of these cytokines was inhibited by pre-treatment with phagocytosis blocker or transfection with siRNAs for IL-10 signaling components. KW3110 treatment also suppressed activation of caspase-1, an active component of inflammasome complexes, in LPS/ATP-stimulated J774A.1 cells, and its effect was inhibited by transfection with siRNAs for IL-10 signaling components. In addition to the effects of KW3110 on J774A.1 cells, KW3110 treatment induced IL-10 production in the supernatants of human monocytes, and KW3110 or IL-10 treatment suppressed caspase-1 activation and IL-1β production in the supernatants of LPS/ATP-stimulated cells. These results suggest that KW3110 suppresses LPS/ATP stimulation-induced caspase-1 activation and IL-1β production by promoting IL-10 production in mouse and human immune cells. Our findings reveal a novel anti-inflammatory mechanism of LAB and the effect of KW3110 on caspase-1 activation is expected to contribute to constructing future preventive strategies for inflammation-related disorders using food ingredients.