Exopolysaccharide from Paecilomyces lilacinus modulates macrophage activities through the TLR4/NF‑κB/MAPK pathway

Identification of immunostimulatory activities and active compounds from sequentially extracted fractions of rhizosphere fungal fermentation broth of Atractylodes macrocephala Koidz. rhizomes

Introduction

Pharmacological studies have shown that the rhizome of Atractylodes macrocephala Koidz. (Compositae), commonly known as atractylodes macrocephala rhizome (AMR), can modulate immunity. Nevertheless, its resources have been largely depleted, and the pharmacological activity of artificial AMR is relatively modest. We hypothesized that the fermented crude extracts of the rhizosphere fungi of AMR would have similar immunomodulatory effects since the metabolites generated by these fungi are similar to those of the host plant given their long-term synergistic evolution.

Methods

Rhizosphere fungi were isolated from the rhizosphere soil of AMR and cultured to produce the secondary metabolites. These metabolites were then sequentially extracted with four solvents of increasing polarities (petroleum ether, ethyl acetate, n-butanol, and water). The in vitro immunomodulatory activities of the metabolite extracts were evaluated by cell proliferation capacity, cell phagocytosis activity, NO secretion capacity, cell morphology changes, and cytokine (TNF-α, IL-1β and IL-6) secretion capacity in RAW264.7 macrophage cells. The biologically active secondary metabolites produced by the rhizosphere fungi were identified using ultrahigh-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS).

Results

Three rhizosphere fungi, namely Penicillium (MK-1), Penicillium glaucoroseum (MN-1), and Purpureocillium lilalium (MG-1), were isolated from the rhizosphere soil of AMR. The assays for cell proliferation capacity, cell phagocytosis activity, and NO secretion capacity showed that all metabolite extracts exhibited in vitro immunomodulatory activities. The crude extracts of MG-1 exhibited the highest levels of in vitro immunomodulatory activities compared to the other extracts. Furthermore, it was demonstrated that the fermented extracts of MG-1 could facilitate immunological enhancement in vitro by altering the cellular morphology in the resting state and increasing the secretions of TNF-α, IL-1β, and IL-6. Meanwhile, there was no observable endotoxin contamination. The metabolite profiling of MG-1 by UHPLC-Q-TOFMS revealed the presence of several compounds with established immunoreactive activities, including L-arginine, prostaglandin I2, deoxyguanosine, bestatin, and osthole.

Discussion

The present study demonstrated that the metabolite extracts of the rhizosphere fungi isolated from the rhizosphere soil of AMR exhibited in vitro immunoreactive activities and that these rhizosphere fungi could produce several bioactive metabolites. The crude extracts of the rhizosphere fungi may hence extend the medicinal utility of AMR and provide a basis for further development of natural plant-based immunomodulators.

Immunostimulatory Activity of a Mixture of Platycodon grandiflorum, Pyrus serotine, Chaenomeles sinensis, and Raphanus sativus in RAW264.7 Macrophages

In this study, a mixture of Platycodon grandiflorum, Pyrus serotina, Chaenomeles sinensis, and Raphanus sativus (PPCRE) was investigated for their immuno-enhancing effects, as well as the molecular mechanism of PPCRE in RAW264.7 cells. PPCRE dramatically increased nitric oxide (NO) and prostaglandin E2 (PGE2) generation depending on the concentration while exhibiting no cytotoxicity. PPCRE markedly upregulated the mRNA and protein expression of immune-related cytotoxic factors such as cyclooxygenase (COX)-1, COX-2, and inducible nitric oxide synthase (iNOS) and pro-inflammatory cytokines such as interleukin (IL)-1β, IL-6, and tumor necrosis factor alpha (TNF-α), as well as the mRNA level of IL-4. PPCRE increased the mitogen-activated protein kinase (MAPK) signaling pathway by upregulating the phosphorylation of extracellular signal-regulated kinase (ERK), stress-activated protein kinase/Jun N-terminal-kinase (SAPK/JNK), and p38. Furthermore, PPCRE considerably activated the nuclear factor kappa B (NF-κB) signaling pathway by increasing phosphorylation of NF-κB-p65. PPCRE-stimulated RAW264.7 cells increased macrophage phagocytic capacity. In conclusion, our study found that PPCRE improved immune function by modulating inflammatory mediators and regulating the MAPK and NF-κB pathway of signaling in macrophages.

Immune Enhancement Effects of Neutral Lipids, Glycolipids, Phospholipids from Halocynthia aurantium Tunic on RAW264.7 Macrophages

Fractionated lipids of Halocynthia aurantium (Pyuridae) have been demonstrated to possess anti-inflammatory properties. However, their modulatory properties have not been reported yet. Thus, the objective of this study was to determine immune enhancing effects of fractionated lipids from H. aurantium tunic on macrophage cells. The tunic of H. aurantium was used to isolate total lipids, which were then subsequently separated into neutral lipids, glycolipids, and phospholipids. RAW264.7 cells were stimulated with different concentrations (0.5, 1.0, 2.0, and 4.0%) of each fractionated lipid. Cytotoxicity, production of NO, expression levels of immune-associated genes, and signaling pathways were then determined. Neutral lipids and glycolipids significantly stimulated NO and PGE2 production and expression levels of IL-1β, IL-6, TNF-α, and COX-2 in a dose-dependent manner, while phospholipids ineffectively induced NO production and mRNA expression. Furthermore, it was found that both neutral lipids and glycolipids increased NF-κB p-65, p38, ERK1/2, and JNK phosphorylation, suggesting that these lipids might enhance immunity by activating NF-κB and MAPK signaling pathways. In addition, H. aurantium lipids-induced TNF-α expression was decreased by blocking MAPK or NF-κB signaling pathways. Phagocytic activity of RAW 264.7 cells was also significantly enhanced by neutral lipids and glycolipids. These results suggest that neutral lipids and glycolipids from H. aurantium tunic have potential as immune-enhancing materials.

Molecular Characterization and Biocompatibility of Exopolysaccharide Produced by Moderately Halophilic Bacterium Virgibacillus dokdonensis from the Saltern of Kumta Coast

The use of natural polysaccharides as biomaterials is gaining importance in tissue engineering due to their inherent biocompatibility. In this direction, the present study aims to explore the structure and biocompatibility of the EPS produced by Virgibacillus dokdonensis VITP14. This marine bacterium produces 17.3 g/L of EPS at 96 h of fermentation. The EPS was purified using ion exchange and gel permeation chromatographic methods. The porous web-like structure and elemental composition (C, O, Na, Mg, P, S) of the EPS were inferred from SEM and EDX analysis. AFM analysis revealed spike-like lumps with a surface roughness of 84.85 nm. The zeta potential value of −10 mV indicates the anionic nature of the EPS. Initial molecular characterization showed that the EPS is a heteropolysaccharide composed of glucose (25.8%), ribose (18.6%), fructose (31.5%), and xylose (24%), which are the monosaccharide units in the HPLC analysis. The FTIR spectrum indicates the presence of functional groups/bonds typical of EPSs (O-H, C-H, C-O-H, C-O, S=O, and P=O). The polymer has an average molecular weight of 555 kDa. Further, NMR analysis revealed the monomer composition, the existence of two α- and six β-glycosidic linkages, and the branched repeating unit as → 1)[α-D-Xylp-(1 → 2)-α-D-Glcp-(1 → 6)-β-D-Glcp-(1 → 5)]-β-D-Frup-(2 → 2)[β-D-Xylp-(1 → 4)]-β-D-Xylp-(1 → 6)-β-D-Fruf-(2 → 4)-β-D-Ribp-(1 →. The EPS is thermally stable till 251.4 °C. X-ray diffraction analysis confirmed the semicrystalline (54.2%) nature of the EPS. Further, the EPS exhibits significant water solubility (76.5%), water-holding capacity (266.8%), emulsifying index (66.8%), hemocompatibility (erythrocyte protection > 87%), and cytocompatibility (cell viability > 80% on RAW264.7 and keratinocyte HaCaT cells) at higher concentrations and prolongs coagulation time in APTT and PT tests. Our research unveils the significant biocompatibility of VITP14 EPS for synthesizing a variety of biomaterials.

Inducible nitric oxide synthase regulates macrophage polarization via the MAPK signals in concanavalin A-induced hepatitis

INTRODUCTION

Acute liver inflammatory reactions contribute to many health problems; thus, it is critical to understand the underlying pathogenic mechanisms of acute hepatitis. In this study, an experimental in vivo model of concanavalin A (ConA)-induced hepatitis was used.

MATERIALS AND METHODS

C57BL/6 (wild-type, WT) or inducible nitric oxide synthase-deficient (iNOS-/- ) mice were injected with PBS or 15 mg/kg ConA via tail vein. Detection of liver injury by histological examination and apoptosis, and flow cytometry to detect the effect of immune cells on liver injury.

RESULTS

iNOS-/-  mice had lower levels of the liver enzymes aspartate aminotransferase and alanine aminotransferase, suggesting that they were protected against ConA-induced pathological liver injury and that iNOS participated in the regulation of hepatitis. Furthermore, iNOS deficiency was found to lower CD86 expression and suppressed the messenger RNA levels of inflammatory factors in the liver. In vitro experiments also demonstrated that iNOS deficiency suppressed the sequential phosphorylation of the mitogen-activated protein kinase pathway cascade, thereby inhibiting the M1 polarization of macrophages and consequently suppressing the transcription of inflammation factors.

CONCLUSION

iNOS may contribute to ConA-induced inflammation by promoting the activation of proinflammatory macrophages.

Myeloid Angiotensin II Type 1 Receptor Mediates Macrophage Polarization and Promotes Vascular Injury in DOCA/Salt Hypertensive Mice

Activation of the renin–angiotensin system has been implicated in hypertension. Angiotensin (Ang) II is a potent proinflammatory mediator. The present study investigated the role of myeloid angiotensin type 1 receptor (AT1R) in control of macrophage phenotype in vitro and vascular injury in deoxycorticosterone acetate (DOCA)/salt hypertension. In human THP-1/macrophages, Ang II increased mRNA expressions of M1 cytokines and decreased M2 cytokine expressions. Overexpression of AT1R further increased Ang II-induced expressions of M1 cytokines and decreased M2 cytokines. Silenced AT1R reversed Ang II-induced changes in M1 and M2 cytokines. Ang II upregulated hypoxia-inducible factor (HIF)1α, toll-like receptor (TLR)4, and the ratio of pIκB/IκB, which were prevented by silenced AT1R. Silenced HIF1α prevented Ang II activation of the TLR4/NFκB pathway. Furthermore, Ang II increased HIF1α via reactive oxygen species-dependent reduction in prolyl hydroxylase domain protein 2 (PHD2) expression. The expressions of AT1R and HIF1α and the ratio of pIκB/IκB were upregulated in the peritoneal macrophages of DOCA hypertensive mice, and the specific deletion of myeloid AT1R attenuated cardiac and vascular injury and vascular oxidative stress, reduced the recruitment of macrophages and M1 cytokine expressions, and improved endothelial function without significant reduction in blood pressure. Our results demonstrate that Ang II/AT1R controls the macrophage phenotype via stimulating the HIF1α/NFκB pathway, and specific myeloid AT1R KO improves endothelial function, vascular inflammation, and injury in salt-sensitive hypertension. The results support the notion that myeloid AT1R plays an important role in the regulation of the macrophage phenotype, and dysfunction of this receptor may promote vascular dysfunction and injury in salt-sensitive hypertension.

Inflammatory biomarkers on an LPS-induced RAW 264.7 cell model: a systematic review and meta-analysis

INTRODUCTION

Several experimental models have been designed to promote the development of new anti-inflammatory drugs. The in vitro model using RAW 264.7 cells has been widely used. However, there is still no consensus on which inflammatory mediators should initially be measured to screen for possible anti-inflammatory effects. To determine the rationality of measuring inflammatory mediators together with NO, such as the levels of tumor necrosis factor (TNF)-α, and interleukins (IL) 1β and 6, we carried out this systematic review (SR) and meta-analysis (MA).

METHODOLOGY

We conducted this SR and MA in accordance with the Preferred Reporting of Systematic Reviews and Meta-Analysis and the Cochrane Handbook for Systematic Reviews of Intervention. This review was registered in the Open Science Framework ( https://doi.org/10.17605/OSF.IO/8C3HT ).

RESULTS

LPS-induced cells produced high NO levels compared to non-LPS induced, and this production was not related to cell density. TNF-α, IL-1β, and IL-6, also showed high levels after cells had been stimulated with LPS. Though with some restrictions, all studies were reliable, as the risk of bias was detected in the test compounds and systems.

CONCLUSION

Measurement of NO levels may be sufficient to screen for possible anti-inflammatory action in the context of LPS-induced RAW 264.7 cells.