Bacteria-triggered sepsis is characterized by systemic, uncontrolled inflammation in affected individuals. Controlling the excessive production of pro-inflammatory cytokines and subsequent organ dysfunction in sepsis remains challenging. Here, we demonstrate that Spi2a upregulation in lipopolysaccharide (LPS)-stimulated bone marrow-derived macrophages reduces the production of pro-inflammatory cytokines and myocardial impairment. In addition, exposure to LPS upregulates the lysine acetyltransferase, KAT2B, to promote METTL14 protein stability through acetylation at K398, leading to the increased m ⁶ A methylation of Spi2a in macrophages. m ⁶ A-methylated Spi2a directly binds to IKKβ to impair IKK complex formation and inactivate the NF-κB pathway. The loss of m ⁶ A methylation in macrophages aggravates cytokine production and myocardial damage in mice under septic conditions, whereas forced expression of Spi2a reverses this phenotype. In septic patients, the mRNA expression levels of the human orthologue SERPINA3 negatively correlates with those of the cytokines, TNF, IL-6, IL-1β and IFNγ. Altogether, these findings suggest that m ⁶ A methylation of Spi2a negatively regulates macrophage activation in the context of sepsis.

Oral lichen planus (OLP) is known as a chronic inflammatory disease. Our recent studies have suggested that vitamin D/vitamin D receptor (VDR) signaling exerts its protective effects on oral keratinocyte apoptosis by regulating microRNA-802 and p53-upregulated modulator of apoptosis (PUMA), but its roles in oral epithelial inflammatory responses in OLP are still unknown. Herein, we identify lipopolysaccharide (LPS) is able to enhance interferon gamma (IFNγ) and interleukin-1 beta (IL-1β) productions in human oral keratinocytes (HOKs) dependent on hypoxia-inducible factor-1α (HIF-1α). HIF-1α and cytokines levels in HOKs were investigated by real-time PCR and western blotting after LPS challenge. The effects of 1,25(OH)2D3 on LPS-induced HIF-1α and cytokines were tested by real-time PCR, western blotting, siRNA-interference and plasmids transfection techniques. The roles of 1,25(OH)2D3 in regulating HIF-1α levels were investigated using western blotting, siRNA-interference, plasmids transfection and Chromatin Immunoprecipitation (ChIP) assays. Finally, HIF-1α, IFNγ and IL-1β expressions in oral epithelia derived from mice and individuals were measured by real-time PCR, western blotting and immunohistochemical staining. As a critical regulator, vitamin D suppresses LPS-induced HIF-1α to block IFNγ and IL-1β productions. Mechanistically, vitamin D inactivates nuclear factor-κB (NF-κB) pathway and up-regulates von Hippel-Lindau (VHL) levels, leading to HIF-1α reduction. Moreover, HIF-1α status of oral epithelia is elevated in VDR−/− mie as well as in VDR-deficient human biopsies, accompanied with increased IFNγ and IL-1β. Collectively, this study uncovers an unrecognized roles of vitamin D/VDR signaling in regulating cytokines in oral keratinocytes and reveals the molecular basis of it.

The nuclear N ⁶ ‐methyladenosine (m ⁶ A) reader YT521‐B homology‐domain‐containing protein 1 (YTHDC1) is required to maintain embryonic stem cell identity. However, little is known about its biological functions in intestinal‐resident macrophages and inflammatory bowel disease (IBD). Herein, it is demonstrated that macrophage‐specific depletion or insufficiency of YTHDC1 accelerates IBD development in animal models. On the molecular basis, YTHDC1 reduction in IBD‐derived macrophages is attributed to Zinc finger protein 36 (ZFP36)‐induced mRNA degradation. Importantly, transcriptome profiling and mechanistic assays unveil that YTHDC1 in macrophages regulates Ras homolog family member H (RHOH) to suppress inflammatory responses and fine‐tunes NME nucleoside diphosphate kinase 1 (NME1) to enhance the integrity of colonic epithelial barrier, respectively. Collectively, this study identifies YTHDC1 as an important factor for the resolution of inflammatory responses and restoration of colonic epithelial barrier in the setting of IBD.

Cardiac glycosides are plant-derived steroid-like compounds which have been used for the treatment of cardiovascular diseases. Ouabain, a cardiotonic steroid and specific Na⁺/K⁺-ATPase inhibitor, has been rediscovered for its potential use in the treatment of cancer. However, the cellular targets and anticancer mechanism of ouabain in various cancers remain largely unexplored. In this study, we confirmed the cytotoxic effects of ouabain on several cancer cell lines. Further examination revealed the increase of apoptosis, intracellular ROS generation and DNA double-strand breaks induced by ouabain treatment. Besides, ouabain effectively suppressed STAT3 expression as well as phosphorylation in addition to block STAT3-mediated transcription and downstream target proteins. Interestingly, these inhibitory activities seemed to be independent of the Na⁺/K⁺-ATPase. Furthermore, we found that ouabain inhibited protein synthesis through regulation of the eukaryotic initiation factor 4E (eIF4E) and eIF4E binding protein 1 (4EBP1). Taken together, our study provided a novel molecular insight of anticancer activities of ouabain in human cancer cells, which could raise the hope of using cardiac glycosides for cancer therapeutics more rational.

Vitamin D is known to play a protective role in inflammatory diseases. Although the suppressive effect of vitamin D/vitamin D receptor (VDR) signaling has been shown in the context of oral lichen planus (OLP), the molecular basis of its regulatory function remains poorly understood. Herein, we reported that miR‐802 over‐expression in OLP could aggravate apoptosis of oral keratinocytes by targeting B‐cell lymphoma 2 mRNA. In addition, vitamin D/VDR signaling was able to suppress miR‐802 expression in LPS‐treated or activated CD4 ⁺ T cell‐stimulated human oral keratinocytes by blocking NF‐κB pathways, thereby inhibiting OLP apoptosis. Consistent with the results in vitro , we showed that miR‐802 expression was enhanced in oral keratinocytes from VDR ^‐/‐ mice, and an inverse correlation between VDR and miR‐802 was found in human biopsy specimens of OLP. Collectively, our data suggest that vitamin D/VDR signaling suppresses oral keratinocyte apoptosis by targeting miR‐802.—Zhao, B., Xu, N., Li, R., Yu, F., Zhang, F., Yang, F., Ge, X., Li, Y. C., Du, J. Vitamin D/VDR signaling suppresses microRNA‐802‐induced apoptosis of keratinocytes in oral lichen planus. FASEB J. 33, 1042–1050 (2019). www.fasebj.org