Molecular pathogenicity of 1-nonadecene and L-lactic acid, unique metabolites in radicular cysts and periapical granulomas

Recently, 1-nonadecene and L-lactic acid were identified as unique metabolites in radicular cysts and periapical granuloma, respectively. However, the biological roles of these metabolites were unknown. Therefore, we aimed to investigate the inflammatory and mesenchymal-epithelial transition (MET) effects of 1-nonadecene, and the inflammatory and collagen precipitation effects of L-lactic acid on both periodontal ligament fibroblasts (PdLFs) and peripheral blood mononuclear cells (PBMCs). PdLFs and PBMCs were treated with 1-nonadecene and L-lactic acid. Cytokines' expression was measured using quantitative real-time polymerase chain reaction (qRT-PCR). E-cadherin, N-cadherin, and macrophage polarization markers were measured using flow cytometry. The collagen, matrix metalloproteinase (MMP)-1, and released cytokines were measured using collagen assay, western blot, and Luminex assay, respectively. In PdLFs, 1-nonadecene enhances inflammation through the upregulation of some inflammatory cytokines including IL-1β, IL-6, IL-12A, monocyte chemoattractant protein (MCP)-1, and platelet-derived growth factor (PDGF) α. 1-Nonadecene also induced MET through the upregulation of E-cadherin and the downregulation of N-cadherin in PdLFs. 1-Nonadecene polarized macrophages to a pro-inflammatory phenotype and suppressed their cytokines' release. L-lactic acid exerted a differential impact on the inflammation and proliferation markers. Intriguingly, L-lactic acid induced fibrosis-like effects by enhancing collagen synthesis, while inhibiting MMP-1 release in PdLFs. These results provide a deeper understanding of 1-nonadecene and L-lactic acid's roles in modulating the microenvironment of the periapical area. Consequently, further clinical investigation can be employed for target therapy.

The Essential Role of 17-Octadecynoic Acid in the Pathogenesis of Periapical Abscesses

INTRODUCTION

Periapical abscesses are 1 of the most frequent pathologic lesions in the alveolar bone. Recently, we have identified 17-octadecynoic acid (17-ODYA) as the highest unique metabolite in periapical abscesses. Therefore, the aim of this study was to investigate the immunologic and pathophysiological roles of this metabolite in the initiation and development of periapical abscesses.

METHODS

Periodontal ligament fibroblasts and peripheral blood mononuclear cells were treated with 17-ODYA. Gene expression analysis and interleukin (IL)-8 release were determined using quantitative real-time polymerase chain reaction and enzyme-linked immunosorbent assay. Macrophage polarization and cytokine release were also determined using flow cytometry and Luminex bioassay (R&D Systems, Minneapolis, MN), respectively.

RESULTS

In periodontal ligament fibroblasts, 17-ODYA caused significant (P < .0001) up-regulation of IL-1α, IL-1β, IL-6, matrix metalloproteinase-1, and monocyte chemoattractant protein-1 at 10 μmol/L after 6 days of treatment and up-regulation of platelet-derived growth factor alpha and vascular endothelial growth factor alpha at all tested concentrations after 2 days of treatment. In peripheral blood mononuclear cells, 17-ODYA significantly increased the expression of IL-1α, IL-1β, IL-6, matrix metalloproteinase-1, and monocyte chemoattractant protein-1 at 10 μmol/L (P < .0001) and vascular endothelial growth factor alpha and platelet-derived growth factor alpha at 1 μmol/L 17-ODYA (P < .0001). 17-ODYA polarized macrophages toward a proinflammatory phenotype (M1) and suppressed the release of pro- and anti-inflammatory cytokines. 17-ODYA significantly enhanced the release of IL-8.

CONCLUSIONS

This study was the first to identify the pathologic role of 17-ODYA in the development of periapical abscesses. The results of this study are important in shedding light on the pathogenesis of periapical abscesses in relation to microbial metabolites.

Comparative sphingolipidomic analysis reveals significant differences between doxorubicin-sensitive and -resistance MCF-7 cells

Drug resistance is responsible for the failure of many available anticancer drugs. Several studies have demonstrated the association between the alteration in sphingolipids (SPLs) and the development of drug resistance. To investigate the association between SPLs metabolism and doxorubicin (dox)-resistance in MCF-7 cells, a comparative sphingolipidomics analysis between dox-sensitive (parental) and -resistant MCF-7 cell lines along with validation by gene expression analysis were conducted. A total of 31 SPLs representing 5 subcategories were identified. The data obtained revealed that SPLs were clustered into two groups differentiating parental from dox-resistant cells. Eight SPLs were significantly altered in response to dox-resistance including SM (d18:1/16), SM (d18:1/24:2), SM (d18:1/24:0), SM (d18:1/20:0), SM (d18:1/23:1), HexCer (d18:1/24:0), SM (d18:1/15:0), DHSM (d18:0/20:0). The current study is the first to conclusively ascertain the potential involvement of dysregulated SPLs in dox-resistance in MCF-7 cells. SPLs metabolism in dox-resistant MCF-7 cells is oriented toward the downregulation of ceramides (Cer) and the concomitant increase in sphingomyelin (SM). Gene expression analysis has revealed that dox-resistant cells tend to escape from the Cer-related apoptosis by the activation of SM-Cer and GluCer-LacCer-ganglioside pathways. The enzymes that were correlated to the alteration in SPLs metabolism of dox-resistant MCF-7 cells and significantly altered in gene expression can represent potential targets that can represent a winning strategy for the future development of promising anticancer drugs.

Potential Therapeutic Strategies for Lung and Breast Cancers through Understanding the Anti-Angiogenesis Resistance Mechanisms

Breast and lung cancers are among the top cancer types in terms of incidence and mortality burden worldwide. One of the challenges in the treatment of breast and lung cancers is their resistance to administered drugs, as observed with angiogenesis inhibitors. Based on clinical and pre-clinical findings, these two types of cancers have gained the ability to resist angiogenesis inhibitors through several mechanisms that rely on cellular and extracellular factors. This resistance is mediated through angiogenesis-independent vascularization, and it is related to cancer cells and their microenvironment. The mechanisms that cancer cells utilize include metabolic symbiosis and invasion, and they also take advantage of neighboring cells like macrophages, endothelial cells, myeloid and adipose cells. Overcoming resistance is of great interest, and researchers are investigating possible strategies to enhance sensitivity towards angiogenesis inhibitors. These strategies involved targeting multiple players in angiogenesis, epigenetics, hypoxia, cellular metabolism and the immune system. This review aims to discuss the mechanisms of resistance to angiogenesis inhibitors and to highlight recently developed approaches to overcome this resistance.