Interleukin-1β expression in murine J774A.1 macrophages exposed to platinum compounds: The role of p38 and ERK 1/2 mitogen-activated protein kinases

Curcumin steers THP-1 cells under LPS and mTORC1 challenges toward phenotypically resting, low cytokine-producing macrophages

The persistent activation of intestinal mechanistic target of rapamycin complex 1 (mTORC1) triggered by mucosal stress has been linked to deregulation of the gut immune response resulting in intestinal inflammation and cell death. The present study investigated the regulatory properties of food-derived mTORC1 modulators, curcumin, and piperine, toward the polarization of stimulated macrophages and the differentiation of monocytes at two mTORC1 activity levels (baseline and elevated). To that end, we created stable human THP-1 monocytes exhibiting normal or constitutively active mTORC1. Curcumin or its combination with piperine, but not piperine alone, suppressed mTORC1 kinase activity, curtailed lipopolysaccharide-mediated inflammatory response of THP-1 macrophages, and repressed macrophage activation by inhibiting signaling pathways involved in M1 (mTORC1) and M2 (mTORC2 and cAMP response element binding protein) polarization. The effects of piperine in the curcumin/piperine combination were modest overall, indicating it was curcumin that modulated differentiating monocytes into acquiring a M0 macrophage phenotype characterized by low inflammatory cytokine output.

β-Carotene attenuates LPS-induced rat intestinal inflammation via modulating autophagy and regulating the JAK2/STAT3 and JNK/p38 MAPK signaling pathways

Inflammation is a protective response of the immune defense system and inflammatory response could be regulated by autophagy. β-Carotene has shown anti-inflammatory potential. However, whether β-carotene could alleviate rat intestinal inflammation by modulating autophagy and its anti-inflammation underlying mechanisms remain unknown. In this study, we found that β-carotene significantly reduced (p < .05) the production of nitric oxide (NO), prostaglandin (PG)E2, tumor necrosis factor (TNF)-α, and interleukin-1β (IL-1β) levels by the Griess reaction and enzyme-linked immunosorbent assay (ELISA), and we found that β-carotene significantly suppressed (p < .05) the mRNA expression levels of IL-1β and TNF-α by RT-PCR. In addition, H&E staining revealed that β-carotene could improve intestinal morphology and cell morphology. Furthermore, the levels of signaling proteins of microtubule-associated protein light chain 3 (LC3), AKT, Janus kinase 2/signal transducers and activators of transcription 3 (JAK2/STAT3), nuclear factor-kappa B (NF-κB), and c-Jun N-terminal kinase (JNK)/p38 mitogen-activated protein kinase (MAPK) were detected by Western blot analysis. We found that β-carotene significantly attenuated (p < .05) the related signaling proteins activated by lipopolysaccharide (LPS) stimulation in rats. Moreover, this conclusion was also verified in intestinal epithelial cell (IEC)-6. 3-Methyladenine (3-MA) is widely used as inhibitor of autophagy via its inhibitory effect on class III PI3K. Simultaneously, pretreatment of 3-MA suppressed the inhibiting effects of β-carotene on the related signaling proteins. This study demonstrates that β-carotene could attenuate the LPS-induced intestinal inflammation in rats via modulating autophagy and regulating the JAK2/STAT3 and JNK/p38 MAPK signaling pathways. We also found the same phenomenon when we verified the results with the IEC-6 cells. These findings provide new insights into improving the nutritional value of basic diets and enhancing immune performance. PRACTICAL APPLICATIONS: β-Carotene is a generally acknowledged natural carotenoid nutrient that exhibits provitamin A activity, and it is widely found in fruits or vegetables. Our study provide a new insight into the anti-inflammatory mechanism of β-carotene. Treatment with β-carotene can be used for the beneficial effect against LPS-induced inflammation damage. This study not only lays the foundation for the related research on the anti-inflammatory properties of β-carotene in vitro and in rat models, but also holds important significance in the field of food.

Falcarindiol inhibits LPS-induced inflammation via attenuating MAPK and JAK-STAT signaling pathways in murine macrophage RAW 264.7 cells

Falcarindiol (FAD) is a natural polyacetylene compound found rich in many plants of the Umbelliferae family. Previously, we isolated FAD from the rhizome of Cnidium officinale Makino, which belongs to the Umbelliferae family and found it to have a significant inhibitory effect on lipopolysaccharide (LPS)-induced production of nitric oxide, a pro-inflammatory molecule in murine macrophage RAW 264.7 cells. In this study, we investigated its effect on the expression of other major pro-inflammatory molecules as well as the mechanism underlying these effects. Pre-treatment of RAW 264.7 cells with FAD suppressed LPS-stimulated mRNA expression of inducible nitric oxide synthase (iNOS), tumor necrosis factor alpha (TNFα), interleukin-6 (IL-6), and interleukin-1 beta (IL-1β) and thereby reduced the respective protein levels. Mechanistic studies demonstrated that FAD attenuated the LPS-induced activation of JNK, ERK, STAT1, and STAT3 signaling molecules. Moreover, we found that FAD did not influence LPS-induced activation of p38 and NFκB signaling pathways. Collectively, this study provides evidence that FAD inhibits the production of major pro-inflammatory molecules in LPS-challenged murine macrophages via suppression of JNK, ERK, and STAT signaling pathways.