Triptolide attenuates LPS-induced activation of RAW 264.7 macrophages by inducing M1-to-M2 repolarization via the mTOR/STAT3 signaling

Fatty acids promote M1 polarization of monocyte-derived macrophages in healthy or ketotic dairy cows and a bovine macrophage cell line via impairing mTOR-mediated autophagy

Excessive concentrations of free fatty acids (FFA) are the main factors causing immune dysfunction and inflammation in dairy cows with ketosis. Polarization of macrophages (the process of macrophages freely switching from one phenotype to another) into M1 or M2 phenotypes is an important event during inflammation induced by environmental stimuli. In non-ruminants, mammalian target of rapamycin (mTOR)-mediated autophagy (a major waste degradation process) regulates macrophage polarization. Thus, the objective was to unravel the role of mTOR-mediated autophagy on macrophage polarization in ketotic dairy cows. Four experiments were performed as follows: (1) In vitro differentiated monocyte-derived macrophages from healthy dairy cows or dairy cows with clinical ketosis (CK) were treated with 100 ng/mL lipopolysaccharide (LPS) and 100 ng/mL interferon-γ (IFN-γ) or 10 ng/mL interleukin-4 (IL4) and 10 ng/mL interleukin-10 (IL10) for 24 h; (2) Immortalized bovine macrophages were treated with 0, 0.3, 0.6, 1.2 mM FFA and LPS and IFN-γ or IL4 and IL10 for 24 h; (3) Macrophages were pretreated with 2 μM 4,6-dimorpholino-N-(4-nitrophenyl)-1,3,5-triazin-2-amine (MHY1485) for 30 min before treatment with LPS and IFN-γ or IL4 and IL10; (4) Macrophages were pretreated with 100 nM rapamycin (RAPA) for 2 h before treatment with LPS and IFN-γ or IL4 and IL10. Compared with healthy cows, cows with CK had a greater mean fluorescence intensity (MFI) of CD86+, but lower MFI of CD206+ and lower number of autophagosomes and autolysosomes in macrophages. Exogenous FFA treatment upregulated protein abundance of inducible nitric oxide synthase (iNOS) and mean fluorescence intensity of CD86, whereas it downregulated the protein abundance of arginase 1 (ARG1) and mean fluorescence intensity of CD206. In addition, FFA increased the p-p65/p65 protein abundance and tumor necrosis factor α (TNFA), interleukin-1B (IL1B), and interleukin-6 (IL6) mRNA abundance, but decreased LC3-phosphatidylethanolamine conjugate (LC3-II) protein abundance and autophagosomes and autolysosomes number. Pretreatment with MHY1485 promoted macrophage M1 polarization and inhibited macrophage M2 polarization via decreased mTOR-mediated autophagy. Activation of mTOR-mediated autophagy by pretreatment with RAPA attenuated the upregulation of inflammation in M1 macrophages that was induced by FFA. These data revealed that high concentrations of FFA promote macrophage M1 polarization in ketotic dairy cows via impairing mTOR-mediated autophagy.

Antitumor mechanisms and future clinical applications of the natural product triptolide

Triptolide (TPL) is a compound sourced from Tripterygium wilfordii Hook. F., a traditional Chinese medicinal herb recognized for its impressive anti-inflammatory, anti-angiogenic, immunosuppressive, and antitumor qualities. Notwithstanding its favorable attributes, the precise mechanism through which TPL influences tumor cells remains enigmatic. Its toxicity and limited water solubility significantly impede the clinical application of TPL. We offer a comprehensive overview of recent research endeavors aimed at unraveling the antitumor mechanism of TPL in this review. Additionally, we briefly discuss current strategies to effectively manage the challenges associated with TPL in future clinical applications. By compiling this information, we aim to enhance the understanding of the underlying mechanisms involved in TPL and identify potential avenues for further advancement in antitumor therapy.

Triptolide attenuates cardiac remodeling by inhibiting pyroptosis and EndMT via modulating USP14/Keap1/Nrf2 pathway

Background

Cardiac remodeling is a common pathological feature in many cardiac diseases, characterized by cardiac hypertrophy and fibrosis. Triptolide (TP) is a natural compound derived from Tripterygium wilfordii Hook F. However, the related mechanism of it in cardiac remodeling has not been fully understood.

Methods and results

Transverse aortic constriction (TAC)-induced cardiac hypertrophic mouse model and angiotensin II (Ang II)-induced cardiomyocytes hypertrophic model were performed. Firstly, the results indicate that TP can improve cardiac function, decreased cardiomyocyte surface area and fibrosis area, as well as lowered the protein expressions of brain natriuretic peptide (BNP), β-major histocompatibility complex (β-MHC), type I and III collagen (Col I and III). Secondly, TP suppressed cardiac pyroptosis, and decreased the levels of Interleukin-1β (IL-1β), Interleukin-18 (IL-18) by Enzyme-linked immunosorbent assay (ELISA), and pyroptosis-associated proteins. Furthermore, TP enhanced the expressions of Nuclear factor erythroid 2-related factor 2 (Nrf2) and Heme oxygenase 1 (HO-1). Interestingly, when Nrf2 was silenced by siRNA, TP lost its properties of reducing pyroptosis and cardiac hypertrophy. In addition, in the Transforming Growth Factor β1 (TGF-β1)-induced primary human coronary artery endothelial cells (HCAEC) model, TP was found to inhibit the process of endothelial-to-mesenchymal transition (EndMT), characterized by the loss of endothelial-specific markers and the gain of mesenchymal markers. This was accompanied by a suppression of Slug, Snail, and Twist expression. Meanwhile, the inhibitory effect of TP on EndMT was weakened when Nrf2 was silenced by siRNA. Lastly, potential targets of TP were identified through network pharmacology analysis, and found that Ubiquitin-Specific Protease 14 (USP14) was one of them. Simultaneously, the data indicated that decrease the upregulation of USP14 and Kelch-like ECH-Associated Protein 1 (Keap1) caused by cardiac remodeling. However, Keap1 was decreased and Nrf2 was increased when USP14 was silenced. Furthermore, CoIP analysis showed that USP14 directly interacts with Keap1.

Conclusion

TP can observably reduce pyroptosis and EndMT by targeting the USP14/Keap1/Nrf2 pathway, thereby significantly attenuating cardiac remodeling.

Inhibition of cGAS-STING pathway by stress granules after activation of M2 macrophages by human mesenchymal stem cells against drug induced liver injury

OBJECTIVE

Cells can produce stress granules (SGs) to protect itself from damage under stress. The cGAS-STING pathway is one of the important pattern recognition pathways in the natural immune system. This study was investigated whether human mesenchymal stem cells (hMSCs) could protect the liver by inducing M2 macrophages to produce SGs during acute drug induced liver injury (DILI) induced by acetaminophen (APAP).

METHODS

After intragastric administration of APAP in vivo to induce DILI mice model, hMSCs were injected into the tail vein. The co-culture system of hMSCs and M2 macrophages was established in vitro. It was further use SGs inhibitor anisomicin to intervene M2 macrophages. The liver histopathology, liver function, reactive oxygen species (ROS) level, apoptosis pathway, endoplasmic reticulum stress (ERS) level, SGs markers (G3BP1/TIA-1), cGAS-STING pathway, TNF-α, IL-6, IL-1β mRNA levels in liver tissue and M2 macrophages were observed.

RESULTS

In vivo experiments, it showed that hMSCs could alleviate liver injury, inhibite the level of ROS, apoptosis and ERS, protect liver function in DILI mice. The mount of M2 was increased in the liver. hMSCs could also induce the production of SGs, inhibit the cGAS-STING pathway and reduce TNF-α, IL-6, IL-1β mRNA expression. The results in vitro showed that hMSCs could induce the production of SGs in macrophages, inhibit the cGAS-STING pathway, promote the secretion of IL-4 and IL-13, and reduce TNF-α, IL-6, IL-1β mRNA level in cells. In the process of IL-4 inducing M2 macrophage activation, anisomycin could inhibit the production of SGs, activate the cGAS-STING pathway, and promote the inflammatory factor TNF-α, IL-6, IL-1β mRNA expression in cells.

CONCLUSIONS

HMSCs had a protective effect on acute DILI in mice induced by APAP. Its mechanism might involve in activating M2 type macrophages, promoting the production of SGs, inhibiting the cGAS-STING pathway, and reducing the expression of pro-inflammatory factors in macrophages, to reduce hepatocytes damage.

Targeting different phenotypes of macrophages: A potential strategy for natural products to treat inflammatory bone and joint diseases

BACKGROUND

Macrophages, a key class of immune cells, have a dual role in inflammatory responses, switching between anti-inflammatory M2 and pro-inflammatory M1 subtypes depending on the specific environment. Greater numbers of M1 macrophages correlate with increased production of inflammatory chemicals, decreased osteogenic potential, and eventually bone and joint disorders. Therefore, reversing M1 macrophages polarization is advantageous for lowering inflammatory factors. To better treat inflammatory bone disorders in the future, it may be helpful to gain insight into the specific mechanisms and natural products that modulate macrophage polarization.

OBJECTIVE

This review examines the impact of programmed cell death and different cells in the bone microenvironment on macrophage polarization, as well as the effects of natural products on the various phenotypes of macrophages, in order to suggest some possibilities for the treatment of inflammatory osteoarthritic disorders.

METHODS

Using 'macrophage polarization,' 'M1 macrophage' 'M2 macrophage' 'osteoporosis,' 'osteonecrosis of femoral head,' 'osteolysis,' 'gouty arthritis,' 'collagen-induced arthritis,' 'freund's adjuvant-induced arthritis,' 'adjuvant arthritis,' and 'rheumatoid arthritis' as search terms, the relevant literature was searched using the PubMed, the Cochrane Library and Web of Science databases.

RESULTS

Targeting macrophages through different signaling pathways has become a key mechanism for the treatment of inflammatory bone and joint diseases, including HIF-1α, NF-κB, AKT/mTOR, JAK1/2-STAT1, NF-κB, JNK, ERK, p-38α/β, p38/MAPK, PI3K/AKT, AMPK, AMPK/Sirt1, STAT TLR4/NF-κB, TLR4/NLRP3, NAMPT pathway, as well as the programmed cell death autophagy, pyroptosis and ERS.

CONCLUSION

As a result of a search of databases, we have summarized the available experimental and clinical evidence supporting herbal products as potential treatment agents for inflammatory osteoarthropathy. In this paper, we outline the various modulatory effects of natural substances targeting macrophages in various diseases, which may provide insight into drug options and directions for future clinical trials. In spite of this, more mechanistic studies on natural substances, as well as pharmacological, toxicological, and clinical studies are required.

Inflammation, Autoinflammation and Autoimmunity in Inflammatory Bowel Diseases

In this review, the role of innate and adaptive immunity in the pathogenesis of inflammatory bowel diseases (IBD) is reported. In IBD, an altered innate immunity is often found, with increased Th17 and decreased Treg cells infiltrating the intestinal mucosa. An associated increase in inflammatory cytokines, such as IL-1 and TNF-α, and a decrease in anti-inflammatory cytokines, such as IL-10, concur in favoring the persistent inflammation of the gut mucosa. Autoinflammation is highlighted with insights in the role of inflammasomes, which activation by exogenous or endogenous triggers might be favored by mutations of NOD and NLRP proteins. Autoimmunity mechanisms also take place in IBD pathogenesis and in this context of a persistent immune stimulation by bacterial antigens and antigens derived from intestinal cells degradation, the adaptive immune response takes place and results in antibodies and autoantibodies production, a frequent finding in these diseases. Inflammation, autoinflammation and autoimmunity concur in altering the mucus layer and enhancing intestinal permeability, which sustains the vicious cycle of further mucosal inflammation.

Celastrol-loaded biomimetic nanodrug ameliorates APAP-induced liver injury through modulating macrophage polarization

Drug-induced liver injury (DILI) is a major concern in clinical treatment as well as postmarketing surveillance, showing an urgent requirement for the development of protective medications. Celastrol (Cel), a highly active natural product extracted from the roots of Tripterygium wilfordii, has a potential liver protective activity due to its antioxidant and anti-inflammatory effects. However, the further application of Cel to DILI remains a challenge because of its short half-life, low solubility, and toxic side effects. Herein, we developed a Cel-loaded biomimetic nanodrug based on erythrocyte membrane vesicles (EMV) for protecting the liver from acetaminophen (APAP)-induced liver injury. The Cel-loaded EMV (C-EMV) with lower cytotoxicity had a well-sustained release effect and exhibited excellent ability for liver accumulation under physiological and pathological conditions. By suppressing the inflammatory response of pro-inflammatory macrophage M1 polarization while stimulating anti-inflammatory macrophage M2 polarization, C-EMV could significantly alleviate the primary pathological manifestations related to liver injury, including aberrant elevation of biochemical indicators, histopathological alterations, neutrophil infiltration as well as hepatocyte DNA fragmentation. The macrophage depletion experiment further demonstrated that the protective effect of C-EMV on APAP-induced liver injury appeared to be dependent on hepatic macrophages. Therefore, C-EMV as a biomimetic nanodrug exhibits great potential for attenuating the progress of DILI, providing a new approach to protecting the liver from DILI as well as other liver inflammatory diseases through a targeted nanodelivery system. KEY MESSAGES: EMV biomimetic nanocarrier has good monodispersity and sustained-release property. EMV biomimetic nanocarrier displays excellent liver-targeting capability under physiological and pathological conditions. C-EMV biomimetic nanodrug with lower cytotoxicity regulates macrophage polarization in vitro and in vivo. C-EMV biomimetic nanodrug can significantly alleviate APAP-induced liver injury. The protective effect of C-EMV on APAP-induced liver injury is dependent on hepatic macrophages.