Phenotypic Changes and Oxidative Stress in THP-1 Macrophages in Response to Vanilloids Following Stimulation with Allergen Act d 1 and LPS

Activation of macrophages plays a key role in both inflammation and oxidative stress, key features of many chronic diseases. Pro-inflammatory M1-like macrophages, in particular, contribute to pro-oxidative environments and are a frequent focus of immunological research. This research examined the effects of kiwifruit allergen Act d 1, in comparison to LPS, on THP-1 macrophages in vitro differentiated under optimized conditions, both in the presence and in the absence of selected vanilloids. THP-1 monocyte differentiation was optimized by varying PMA exposure and resting time. Act d 1 induced M1-like phenotypic changes comparable to LPS, including upregulation of CD80, IL-1β and IL-6 secretion, gene expression of iNOS and NF-κB activation, in addition to increased reactive oxygen species (ROS) and catalase activity. Treatment with specific vanilloids mitigated these responses, primarily through reduced oxidative stress and NF-κB activation. Notably, vanillin (VN) was the most effective, also reducing CD80 expression and IL-1β levels. These results suggest that vanilloids can affect pro-inflammatory signaling and oxidative stress in THP-1 macrophages and highlight their potential to alter inflammatory conditions characterized by similar immune responses.