Terfezia boudieri and Terfezia claveryi inhibit the LPS/IFN-γ-mediated inflammation in RAW 264.7 macrophages through an Nrf2-independent mechanism

Abstract

Abstract Desert truffles have been used as traditional treatments for numerous inflammatory disorders. However, the molecular mechanisms underlying their anti-inflammatory effects in RAW 264.7 macrophages have yet to be fully elucidated. The present study investigated the anti-inflammatory activities of two main desert truffles, Terfezia boudieri and T. claveryi, and the underlying mechanisms associated with their anti-inflammatory activities in RAW 264.7 macrophages stimulated with lipopolysaccharide/interferon-gamma (LPS/IFN-γ). Our results demonstrated that treatment with T. boudieri and T. claveryi extracts effectively suppressed the inflammatory response in LPS/IFN-γ-stimulated RAW 264.7 macrophages. Specifically, T. boudieri extract was found to reduce the production of nitric oxide and inhibit the expression of various pro-inflammatory markers, including inducible nitric oxide synthase, cyclooxygenase-2 (COX-2), tumor necrosis factor-α, and interleukin-6 (IL-6) at both the mRNA and protein levels. Similarly, T. claveryi extract exhibited comparable inhibitory effects, except for the expression of IL-6 and COX-2 at the protein level, where no significant effect was observed. Moreover, both studied extracts significantly downregulated the microRNA expression levels of miR-21, miR-146a, and miR-155, suggesting that T. boudieri and T. claveryi suppress the inflammatory response in LPS/IFN-γ-stimulated RAW 264.7 cells through an epigenetic mechanism. Furthermore, our study reveals a new mechanism for the anti-inflammatory properties of desert truffle extracts. We show for the first time that Terfezia extracts do not rely on the nuclear factor erythroid 2-related factor 2 pathway, previously linked to anti-inflammatory responses. This expands our understanding of natural product anti-inflammatory mechanisms and could have important implications for developing new therapies. To account for differences in truffle effects, extracts prepared were subjected to secondary metabolites profiling using UPLC-MS. UPLC-MS led to the annotation of 87 secondary metabolites belonging to various classes, including amino acids, carbohydrates, alkaloids, amides, fatty acids, sterols, and phenolic compounds. Therefore, these results indicate that T. boudieri and T. claveryi exhibit anti-inflammatory activities through suppressing multiple inflammatory mediators and cytokines and may be potential anti-inflammatory agents.