Search

Neutrophil extracellular traps (NETs) formation is a key process in inflammatory diseases like gout, but the underlying molecular mechanisms remain incompletely understood. This study aimed to establish a model to examine the formation of NETs induced by monosodium urate (MSU) and phorbol 12-myristate 13-acetate (PMA) and to elucidate their molecular pathways. Laser confocal microscopy was used to visualize NET formation, while flow cytometry was employed to detect reactive oxygen species (ROS) production. The microstructure of neutrophils was observed by transmission electron microscopy, and the expression of key proteins was determined by Western blotting. Additionally, the effect of various inhibitors targeting the MAPK signaling pathway on NET formation was evaluated. They include the Ras inhibitor Salirasib, Raf inhibitor Vemurafenib, ERK inhibitor PD98059, and p38 MAPK inhibitor SB203580, as well as NADPH oxidase inhibitor DPI and neutrophil elastase inhibitor Alvelestat. The results showed that MSU and PMA triggered significant NET formation, which was accompanied by increased ROS levels, lactate dehydrogenase release, dsDNA, and IL-8. Notably, selective MAPK pathway inhibitors and DPI and Alvelestat, except for SB203580, effectively down-regulated these indicators. These data indicated that the activation of a signaling pathway involving Ras-Raf-ERK, which is dependent on ROS, is crucial for the induction of NET formation by MSU and PMA. Given the involvement of NETs in multiple pathologies, our findings could potentially serve as molecular targets for the intervention and treatment of crystal-related diseases, especially for gout. [ABSTRACT FROM AUTHOR]

People's health is adversely impacted by diseases caused by abnormal inflammation; therefore, more effective treatments as well as research into the underlying mechanisms are urgently required. According to our preliminary research, geniposidic acid exhibits anti-inflammatory properties. Even though geniposidic acid has been linked to inflammation and shows promise in the treatment of aberrant inflammatory illnesses, its exact antiinflammatory mechanism is unknown. To create in vitro cellular inflammatory models for 48 h, we employed THP- 1 cells treated with PMA (phorbol 12-myristate 13-acetate) and LPS (lipopolysaccharide), which were then treated with geniposidic acid. These models were further validated by ELISA-based detection of the expression of the interleukins IL-1, IL-6, IL-8, and tumor necrosis factor TNF-κ. The anti-inflammatory properties of geniposidic acid were investigated using proteomics based on TMT-LC-MS/MS analysis and bioinformatic analysis. Geniposidic acid can act as an anti-inflammatory agent in inflammatory cell models, according to the successfully established THP-1 cell inflammatory models. GO and KEGG analyses further established numerous bioprocesses, molecular activities, and signaling pathways related to the regulation of geniposidic acid. Additionally, western blot analysis confirmed that geniposidic acid can suppress inflammation by lowering the expression of proteins linked to inflammation such as CXCL10, PPM1H, and TLR5. After more thorough mechanistic, animal, and clinical research were included, the current study revealed that anti-inflammatory efficacy of geniposidic acid from the standpoint of proteomics made it a promising medicine to cure and prevent diseases caused by aberrant inflammation. [ABSTRACT FROM AUTHOR]

Background: Neutrophil extracellular traps (NETs) consist of chromatin DNA networks that are studded with cytosolic and granular antimicrobial proteins to trap or kill an infected microorganism. A lipid emulsion, the solvent of pure propofol for intravenous application, is given to clinical patients who require intravenous feeding of fatty acids and fat for energy. Intravenous propofol is widely used to sedate critically ill patients. Both intravenous propofol and its lipid emulsion have immunomodulatory activity. However, the role of lipid emulsion of intravenous propofol on NET induction remains unclear. Methods: In this study, neutrophils were stimulated with phorbol myristate acetate (PMA) or Escherichia coli (E. coli) in the absence or presence of intravenous propofol (Propofol-Lipuro®), its solvent lipid emulsion (Lipofundin) or pure propofol, and NETs were stained with SYTOX Green for visualization and quantification. Total HOCl was determined by measuring the taurine-chloramine complex, and intracellular HOCl was evaluated with BioTracker™ TP-HOCl 1 dye. Results: PMA-induced NETs were not efficiently inhibited when Propofol-Lipuro® was added after PMA stimulation. Clinically relevant concentrations of Lipofundin exerted a significant reduction in PMA-induced NETs and total reactive oxidative species (ROS), which was comparable to that observed for Propofol-Lipuro®. Lipofundin transiently reduced intracellular HOCl production and the phosphorylation level of extracellular regulated kinase (p-ERK) but did not scavenge HOCl. Moreover, Lipofundin decreased E. coli-induced NETs in a ROS-independent pathway, similar to Propofol-Lipuro®. Conclusions: All data agree that Lipofundin, the major component of Propofol-Lipuro®, inhibits intracellular HOCl and p-ERK to suppress PMA-induced NET formation but reduces E.coli-induced NETs in a ROS-independent pathway. [ABSTRACT FROM AUTHOR]

Background: Degeneration of nucleus pulposus (NP) cells involves multiple factors. The relationship between the canonical Wnt/β-catenin signaling pathway and matrix metalloproteinases (MMPs) is important in cellular senescence. Protein kinase C (PKC), an intermediate of the non-canonical Wnt pathway stimulated by phorbol myristate acetate (PMA), possibly prevents NP cell senescence, although not yet demonstrated in human-based studies. This study aimed to investigate the effect of PMA stimulation on the non-canonical and canonical Wnt pathways and MMP expression in human NP cells to ascertain its inhibitory effects on the senescence of NP cells., Methods: Human disc tissues of Pfirrmann grades 1 and 2 were collected from patients during spinal surgery and subsequently cultured. Protein and ribonucleic acid (RNA) were isolated from NP cells treated with PMA (400 nM) for 24 hours. Expression of MMP1, MMP13, tissue inhibitor of matrix metalloproteinase 1 (TIMP1), a disintegrin and metalloproteinase with thrombospondin motifs 5 (ADAMTS5), transient receptor potential vanilloid 4 (TRPV4), interleukin-6 (IL-6), and β-catenin were detected using western blot analysis. Messenger RNA (mRNA) expression of type II collagen and glycosaminoglycan (GAG) were analyzed using reverse transcription polymerase chain reaction. IL-6 and prostaglandin E2 (PGE 2 ) levels were measured using enzyme-linked immunosorbent assay., Results: Expression of PKC-δ (intermediate of the non-canonical Wnt pathway) and β-catenin (intermediate of the canonical Wnt pathway) was increased by PMA treatment. The mRNA levels of type II collagen and GAG increased; however, their protein levels were not altered. PMA treatment increased the expression of MMP1, TIMP1, ADAMTS5, IL-6, PGE 2 , and TRPV4; however, the expression of MMP13 and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) was unaltered., Conclusions: PMA activated PKC-δ, affecting the non-canonical Wnt pathway; however, its effect on β-catenin in the canonical Wnt pathway was limited. β-catenin activation through the TRPV4 channel led to increased expression of MMP1 and ADAMTS5 and that of IL-6 and PGE 2 owing to NF-κB expression. Consequently, the degeneration of NP cells was not prevented., Competing Interests: CONFLICT OF INTEREST: No potential conflict of interest relevant to this article was reported., (Copyright © 2024 by The Korean Orthopaedic Association.)

Introduction: The formation of neutrophil extracellular traps (NETs) is a process in which several kinds of enzymes participate generating posttranslational modifications of proteins. NETs have been associated with infectious, autoimmune, and inflammatory diseases. Inhibition of several proteases reduces the formation of NETs. In the present work, we analyzed the role of several broad-acting and specific inhibitors of proteases in the formation of NETs. Methods: Neutrophils were isolated from peripheral blood of healthy individuals by density gradient. The neutrophils were quantified and seeded into cell culture plates. Phorbol myristate acetate and A23187 were used as NETs inducers, and several specific inhibitors of proteases were used. The cells were stained for cytoskeleton or DNA. The cell-free supernatants were used to assess DNA release. Statistical analysis was carried out by a Kruskal-Wallis or ANOVA test. Results: We observed marked changes in actin organization after the induction of NETs, suggesting that the cytoskeleton is being actively regulated. When we used protease inhibitors, the release of DNA was reduced, suggesting the participation of actin remodeling in the process. Further characterization of the specific proteases revealed that calpain modulates the reorganization of actin cytoskeleton and DNA release. Preservation of part of the actin cytoskeleton suggests that DNA release is not only a mechanic process associated to the chromatin decondensation; rather the process is highly regulated by active proteases that promote cytoskeleton reorganization and chromatin decondensation that culminates in DNA release. Conclusion: Calpain mediates the DNA release in the NET formation process by the modification of cortical actin cytoskeleton in a calcium-dependent manner. [ABSTRACT FROM AUTHOR]

THP-1 cells, a human leukemia monocytic cell line, differentiated by phorbol myristate acetate (PMA) are widely used as surrogate of human macrophages. Differentiated THP-1 cells acquire macrophage-like characteristics including more adherence and altered cell function. Nitric oxide (NO), an intracellular messenger, is critical in regulating cell differentiation. Here we elucidated whether NO relates to PMA-induced monocyte-to-macrophage differentiation of THP-1 cells. The mutual regulation of calcium and NO was also investigated. THP-1 cells were incubated with PMA for 24 h, followed by assay of adherence, morphological change, migration or IL-1β release. L-NG-Nitroarginine methyl ester (l -NAME, a nitric oxide synthase inhibitor) or BAPTA-AM (a calcium chelator) was added before PMA stimulation, and levels of calcium and NO were measured. Furthermore, a selective inhibitor of inducible nitric oxide synthase (iNOS) activity was employed to study the role of iNOS. Effects of PMA on upregulation of adherence, lipopolysaccharide-triggered IL-1β, and migration ability of THP-1 cells were consistent with NO concentrations. Both l -NAME and BAPTA-AM mitigated effects of PMA on THP-1 cells differentiation. BAPTA-AM decreased levels of NO, while l -NAME had no effect on calcium levels. Of note, inhibition of iNOS activity decreased PMA-triggered upregulation of NO. PMA induced differentiation of THP-1 cells partially in a NO-dependent manner. The calcium signaling may mediate PMA-triggered upregulation of NO. • Phorbol myristate acetate induces monocyte-to-macrophage differentiation ofTHP-1 cells. • Differentiation of THP-1 cell partially depends on inducible nitric oxide synthase-triggered nitric oxide. • Calcium signaling may mediate upregulation of nitric oxide by phorbol myristate acetate. [ABSTRACT FROM AUTHOR]

Major histocompatibility complex (MHC) class II-associated invariant chain is a chaperone responsible for targeting the MHC class II dimer to the endocytic pathway, thus enabling the loading of exogenous antigens onto the MHC class II receptor. In the current study, in vivo and in vitro methods were used to investigate the regulation of the rainbow trout invariant chain proteins S25-7 and INVX, upon immune system activation. Whole rainbow trout and the macrophage/monocyte-like cell line RTS11 were treated with PMA at concentrations shown to induce IL-1β transcripts and homotypic aggregation of RTS11. S25-7 transcript levels remained unchanged in the gill, spleen, and liver and were found to be significantly decreased in head kidney beginning 24 h post-stimulation. Meanwhile, INVX transcript levels remained unchanged in all tissues studied. Both S25-7 and INVX proteins were produced in gill and spleen tissues but their expression was unaffected by immune system stimulation. Surprisingly, neither INVX nor S25-7 protein was detected in the secondary immune organ, the head kidney. Analysis of RTS11 cultures demonstrated that both INVX and S25-7 transcript levels significantly increased at 96 h and 120 h following PMA stimulation before returning to control levels at 168 h. Meanwhile, at the protein level in RTS11, S25-7 remained unchanged while INVX had a significant decrease at 168 h post-stimulation. These results indicate that neither INVX nor S25-7 is upregulated upon immune system activation; thus, teleosts have evolved a system of immune regulation that is different than that found in mammals. [ABSTRACT FROM AUTHOR]

Phorbol 12-myristate 13-acetate (PMA) promotes skin cancer in rodents. The mutations found in murine tumors are similar to those found in human skin cancers, and PMA promotes proliferation of human skin cells. PMA treatment of human keratinocytes increases the synthesis of APOBEC3A, an enzyme that converts cytosines in single-stranded DNA to uracil, and mutations in a variety of human cancers are attributed to APOBEC3A or APOBEC3B expression. We tested here the possibility that induction of APOBEC3A by PMA causes genomic accumulation of uracils that may lead to such mutations. When a human keratinocyte cell line was treated with PMA, both APOBEC3A and APOBEC3B gene expression increased, anti-APOBEC3A/APOBEC3B antibody bound a protein(s) in the nucleus, and nuclear extracts displayed cytosine deamination activity. Surprisingly, there was little increase in genomic uracils in PMA-treated wild-type or uracil repair-defective cells. In contrast, cells transfected with a plasmid expressing APOBEC3A acquired more genomic uracils. Unexpectedly, PMA treatment, but not APOBEC3A plasmid transfection, caused a cessation in cell growth. Hence, a reduction in single-stranded DNA at replication forks may explain the inability of PMA-induced APOBEC3A/APOBEC3B to increase genomic uracils. These results suggest that the proinflammatory PMA is unlikely to promote extensive APOBEC3A/APOBEC3B-mediated cytosine deaminations in human keratinocytes. [ABSTRACT FROM AUTHOR]

LPA 1 internalization to endosomes was studied employing Förster Resonance Energy Transfer (FRET) in cells coexpressing the mCherry-lysophosphatidic acid LPA 1 receptors and distinct eGFP-tagged Rab proteins. Lysophosphatidic acid (LPA)-induced internalization was rapid and decreased afterward: phorbol myristate acetate (PMA) action was slower and sustained. LPA stimulated LPA 1 -Rab5 interaction rapidly but transiently, whereas PMA action was rapid but sustained. Expression of a Rab5 dominant-negative mutant blocked LPA 1 -Rab5 interaction and receptor internalization. LPA-induced LPA 1 -Rab9 interaction was only observed at 60 min, and LPA 1 -Rab7 interaction after 5 min with LPA and after 60 min with PMA. LPA triggered immediate but transient rapid recycling (i.e., LPA 1 -Rab4 interaction), whereas PMA action was slower but sustained. Agonist-induced slow recycling (LPA 1 -Rab11 interaction) increased at 15 min and remained at this level, whereas PMA action showed early and late peaks. Our results indicate that LPA 1 receptor internalization varies with the stimuli. [Display omitted] • LPA and PMA induce LPA 1 internalization with different time-courses. • LPA 1 -Rab protein FRET was employed to analyze receptor trafficking. • LPA- and PMA-induced differential LPA 1 early endosome association and recycling. • LPA and PMA induce LPA 1 internalization through distinct endocytic routes. [ABSTRACT FROM AUTHOR]

ObjectivesDoxycycline is commonly used in medicine for its bacteriostatic antimicrobial properties. Recent studies have reported that doxycycline also has anti-inflammatory effects. Matrix metalloproteinase (MMP)-9 has been found to be involved in the physiological and pathological process of inflammatory airway disease. Phorbol 12-myristate 13-acetate (PMA), a protein kinase C activator, is known to stimulate the expression of MMP and mucin genes in the airway and intestinal epithelial cells. Therefore, the effects and signal pathways of doxycycline on PMA-induced MUC5B expression dependent MMP-9 in human airway epithelial cells were investigated.MethodsIn human NCI-H292 airway epithelial cells, MUC5B and MMP-9 mRNA expression, MUC5B protein expression, and MMP-9 protein activity after the treatment with PMA, MMP-9 or doxycycline were determined by reverse transcriptase-polymerase chain reaction, enzyme immunoassay, gelatin zymography, and Western blot analysis.ResultsPMA increased MMP-9 and MUC5B expression. MMP-9 increased MUC5B expression. Doxycycline inhibited PMA-induced MUC5B expression, and PMA-induced MMP-9 mRNA expression and protein activity. Doxycycline inhibited phosphorylation of p38 induced by PMA and MMP-9.ConclusionThe results of this study suggest that doxycycline inhibited PMA-induced MUC5B mRNA expression and protein production through the MMP-9 and p38 pathways in human NCI-H292 airway epithelial cells.

Background: CD4 and IL-17 markers can be used for separating TH17 lymphocytes from the population of CD4+ lymphocytes. The best technique for detecting TH17 cells in peripheral blood is flow cytometry in which the cells need to first be activated by phorbol 12-myristate 13-acetate (PMA) and ionomycin. Moreover, monensin is used in order to prevent interleukin 17 (IL-17) secretion out of cells. Methods: Peripheral blood mononuclear cells (PBMC) were separated from freshly isolated heparinized venous blood by centrifugation on a Ficoll-Hypaque (Lymphopreb, Sigma, USA) density gradient. Cell suspension was prepared in three concentrations and cultured with three concentrations of PMA, ionomycin and monensin (each concentration was prepared in three series). Then these were incubated for 6, 12, and 20 hours. Findings: The percentage of TH17 cells was detected by culture of 2 × 106 cells/ml of peripheral blood mononuclear cells with 150 ng/ml of phorbol 12-myristate 13-acetate, 1.5 μM of ionomycin, and 500 ng/ml of monensin and incubation at 37oC in a humidified and 5% CO2 atmosphere for 12 hours. Conclusion: Optimum procedures have to be determined based on the instruments and conditions of each laboratory.