Capsaicin receptor TRPV1 maintains quiescence of hepatic stellate cells in the liver via recruitment of SARM1

Calceolarioside B targets MMP12 in the tumor microenvironment to inhibit M2 macrophage polarization and suppress hepatocellular carcinoma progression

BACKGROUND

Tumor-associated macrophages (TAMs) are crucial in hepatocellular carcinoma (HCC) progression and prognosis, making them promising immunotherapy targets. In traditional Chinese medicine (TCM), qi stagnation and blood stasis are linked to the HCC tumor microenvironment (TME), but few studies explore the effects of related TCM herbs on the TME. Calceolarioside B, a key phenylethanoid glycoside in Akebiae Fructus, has not been well studied for its pharmacological activities or molecular targets, and its role in HCC remains unclear.

PURPOSE

This study aimed to investigate the effects of Calceolarioside B on TAMs in HCC and clarify its potential targets and regulatory mechanisms.

METHODS

Murine intrahepatic transplantation HCC models and macrophage-HCC cell co-culture systems were used to investigate the effects of Calceolarioside B on M2-like TAMs polarization and infiltration, and tumor growth. Cellular thermal shift assay, small molecular pull-down assay and surface plasmon resonance were utilized to identify the potential targets regulating M2-like TAMs. Single-cell RNA sequencing and TCGA dataset analyses clarified the differential expression, prognosis, and TAMs association of the potential targets in HCC.

RESULTS

Calceolarioside B reduces M2-like TAMs polarization and infiltration in the TME by binding to and inhibiting matrix metallopeptidase-12 (MMP12) form both macrophages and HCC cells, thereby preventing immunosuppressive effects. Public database analysis revealed that MMP12 overexpression promoted macrophage infiltration, with MMP12+ macrophages preferentially aggregating in primary and metastatic HCC tumors.

CONCLUSION

Calceolarioside B is identified as a novel MMP12 inhibitor modulating TAMs in the TME, offering a potential TAM-targeting strategy for HCC therapy.

Xiongshao Zhitong granules alleviate nitroglycerin-induced migraine by regulating the TRPV1-mediated NLRP3 inflammatory pathway in rats

BACKGROUND

Migraine is a prevalent neurological disorder accompanied by a considerable economic burden. Xiongshao Zhitong granules (XSZT) have anti-inflammatory and analgesic functions in the clinic and are used for migraine therapy. However, the mechanisms by which XSZT treats migraine remain unclear.

PURPOSE

To discover the underlying mechanism and active ingredients of XSZT in the treatment of migraine.

METHODS

The nitroglycerin (NTG)-induced chronic migraine (CM) model was established and used to detect the therapeutic effect of XSZT on migraine. To elucidate the mechanism, we detected transient receptor potential vanilloid 1 (TRPV1) -mediated NOD-like receptor protein 3 (NLRP3) inflammasome activation in the CM rat model and the LPS-induced inflammatory BV-2 cell model using Western blotting, immunofluorescence and ELISA techniques. The potentially active ingredients of XSZT were determined by UHPLC-LTQ-Orbitrap MS, molecular docking, and surface plasmon resonance.

RESULTS

Our findings revealed that XSZT reduced the number of head scratching, increased the periorbital pain threshold and shortened the time spent in the dark box, decreased c-Fos expression in the CM rat model, suggesting an analgesic effect of XSZT on migraine. XSZT inhibited neurogenic inflammation, including downregulating CGRP, TNF-α, IL-1β and IL-18 levels and decreasing the degranulation rate of mast cells. Additionally, XSZT suppressed the expression and activation of TRPV1 and the NLRP3 inflammasome in the trigeminal nucleus caudalis. In vitro experiments confirmed that activated TRPV1 increased the level of the NLRP3 inflammasome by increasing intracellular calcium levels. Galloylpaeoniflorin, isogastrin, ellagic acid and salvianolic acid A interacted with TRPV1 and inhibited IL-1β secretion.

CONCLUSION

XSZT plays a therapeutic role in migraine through regulating TRPV1-mediated NLRP3 inflammatory activation and galloylpaeoniflorin, isogastrin, ellagic acid and salvianolic acid A might be the active ingredients of XSZT, which provides an experimental basis for the clinical treatment of migraine.

Evolutionarily ancient functions of enzymatic TIR proteins in innate immunity

Proteins with a Toll/interleukin-1 receptor/resistance (TIR) domain are among the most ancient immune regulators and include well-known pattern recognition receptors (PRRs). A specialized subset of TIR domain proteins are enzymes that predominantly use nicotinamide adenine dinucleotide (NAD+) to generate second messenger metabolites. These enzymatic TIR proteins have essential roles in bacteria, plant, and animal immunity. The mechanism of activation of these TIR proteins, conserved across Kingdoms, involves oligomerization into higher-ordered structures, which activates their intrinsic enzymatic activity. Here, we review the functions of enzymatic TIR proteins in innate immunity in bacteria, plants, and animals. This work offers insights into the evolutionary origins of immunity itself and defines fundamental principles of immune surveillance across the Tree of Life.

Capsaicin from chili peppers and its analogues and their valued applications: An updated literature review

Chili peppers are widely sought after by consumers for not only their color, flavor, and nutritional properties but also their main component (capsaicin) various biological activities in diverse fields. Capsaicin (trans-8-methyl-N-vanillyl-6-nonenamide), the compound primarily responsible for the spicy flavor of peppers, remains a hot topic in the scientific community and shows the vast potential in various applications. Although many reviews focus comprehensively on capsaicin, most articles are limited to the medical field of capsaicin. This review provides an overview briefly of the capsaicin and its analogues in the fields of food, medicine and with a particular emphasis on their applications in agriculture and livestock farming. Overall, we aims is to expand the broad spectrum of applications for capsaicin and its analogues and explore their potential biological mechanisms. Finally, the challenges of capsaicin and future development prospects were discussed and proposed.

Sulfonation of Capsaicin by sulfotransferases produces an anti-inflammatory metabolite with NF-κB pathway modulatory activity

Capsaicin (CAP), the principal bioactive component of chili peppers (Capsicum annuum L.), is widely recognized for its anti-inflammatory properties. However, its oral bioavailability is low, likely due to extensive sulfonation metabolism. Despite the well-known pharmacological benefits of CAP, the role of sulfotransferase (SULT)-mediated sulfonation in modulating its therapeutic effects remains poorly understood. This study aims to elucidate the sulfonate metabolic profile of CAP, investigate the anti-inflammatory role of its sulfonate metabolite (CAP-S), and uncover the mechanisms underlying CAP-S's anti-inflammatory effects. In our study, the mono-sulfonate metabolite of CAP, designated as CAP-S ((E)-N-[(4-sulfo-3-methoxyphenyl)methyl]-8-methylnon-6-enamide), is identified using ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) and proton nuclear magnetic resonance (1H-NMR). The metabolic profile of CAP was investigated in liver S9 fractions from human, rat, and mouse samples, with sulfonation of CAP examined using seven major recombinant SULT isoforms. The results demonstrate that CAP is primarily catalyzed by SULT1A subfamily and SULT1E1. The anti-inflammatory effects of CAP-S are evaluated in lipopolysaccharide (LPS)-stimulated RAW264.7 cells and an acute liver injury (ALI) mouse model. CAP-S significantly reduces inflammatory mediators and nitric oxide (NO) production in LPS-induced RAW264.7 cells. In vivo, CAP-S treatment alleviates hepatocyte necrosis, inflammatory cell infiltration, and reduces aspartate aminotransferase, alanine aminotransferase, and malondialdehyde levels, while enhancing superoxide dismutase activity and decreasing NO production. Additionally, CAP-S exerts comparable anti-inflammatory effects to CAP by suppressing NF-κB p65 phosphorylation and reducing pro-inflammatory cytokines, as evidenced by network pharmacology and western blot assays. These findings underscore the role of sulfonation in modulating CAP's therapeutic potential.

Single-cell RNA sequencing advances in revealing the development and progression of MASH: the identifications and interactions of non-parenchymal cells

Developing drugs for the treatment of Metabolic Associated Steatohepatitis (MASH) has always been a significant challenge. Researchers have been dedicated to exploring drugs and therapeutic strategies to alleviate disease progression, but treatments remain limited. This is partly due to the complexity of the pathophysiological processes, and inadequate knowledge of the cellular and molecular mechanisms in MASH. Especially, the liver non-parenchymal cells (NPCs) like Kupffer cells, hepatic stellate cells and sinusoidal endothelial cells which play critical roles in live function, immune responses, fibrosis and disease progression. Deciphering how these cells function in MASH, would help understand the pathophysiological processes and find potential drug targets. In recent years, new technologies have been developed for single-cell transcriptomic sequencing, making cell-specific transcriptome profiling a reality in healthy and diseased livers. In this review, we discussed how the use of single-cell transcriptomic sequencing provided us with an in-depth understanding of the heterogeneous, cellular interactions among non-parenchymal cells and tried to highlight recent discoveries in MASH by this technology. It is hoped that the summarized features and markers of various subclusters in this review could provide a technical reference for further experiments and a theoretical basis for clinical applications.

Discovery of novel capsaicin analogs as TRPV1 inhibitors for the treatment of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive and fatal interstitial lung disease for which few drugs are available in clinical practice. Here, we identified novel capsaicin analogs by combining in-house chemical library screening and further structural optimization. (E)-1-(3,4-dihydroxyphenyl)-7-phenylhept-1-en-3-one (Compound 14) was found to be the most potent in inhibiting TGF-β-induced collagen accumulation, proliferation and migration in fibroblast cells. Furthermore, compound 14 (IC50 = 0.51 ± 0.06 μM) showed over 100-fold increasing antifibrotic activity compared to capsaicin (IC50 = 53.71 ± 4.78 μM). Notably, compound 14 could target TRPV1, thereby affecting the expression of the fibrosis markers Collagen Ⅰ and α-SMA by inhibiting the TGF-β/Smads and MAPK pathways to exert antifibrotic activity in vitro. Compound 14 significantly inhibited collagen deposition in lung tissues, ameliorated alveolar structures, and increased survival rates in mice with bleomycin-induced pulmonary fibrosis. In addition, compound 14 possessed lower cytotoxicity (compared to nitedanib) and no toxicity in mice. Overall, compound 14 promise as a potential drug candidate for the treatment of IPF.

Biosynthesis inhibition of miR-142-5p in a N6-methyladenosine-dependent manner induces neuropathic pain through CDK5/TRPV1 signaling

BACKGROUND

Neuropathic pain (NP) represents a debilitating and refractory condition. However, the understanding of NP and the current treatment approaches available for its management are limited. Therefore, there is a significant need to address the dearth of effective therapeutic interventions. This study aims to investigate the regulation of transient receptor potential vanilloid 1 (TRPV1) and cyclin-dependent kinase 5 (CDK5) expression levels by miR-142-5p as a common upstream molecule, and to delve into the mature process of miR-142-5p from the perspective of N6-methyladenosine (m6A) modification.

METHODS

To assess the RNA levels of TRPV1, CDK5, miR-142-5p, pre-miR-142, and pri-miR-142, quantitative PCR with reverse transcription (RT-qPCR) was utilized. Western blot analysis was employed to determine changes in protein expression for TRPV1 and CDK5. For assessing the interaction mechanism and binding site between TRPV1 and CDK5, various techniques were applied, including mass spectrometry, coimmunoprecipitation (co-IP), and glutathione-S-transferase (GST)-pulldown assays. The subcellular localization of TRPV1 on the cell membrane was visualized through immunofluorescence, and the translocation was confirmed by western blot analysis after performing membrane-plasma separation in parallel. Moreover, intracellular calcium transport was monitored using calcium imaging as an indicator of cell excitability. The binding of miRNA-142-5p to the 3'UTR of TRPV1 and CDK5 was investigated using the dual-luciferase reporter assay. The overall level of m6A was first determined by RNA m6A methylation assay, and subsequently the methylation level of pri-miR-142 was assessed using the meRIP assay to detect m6A modification. In addition, an in vivo rat chronic constriction injury (CCI) model was established, and miR-142-5p agomir or antagomir was injected intrathecally. An enzyme-linked immunosorbent assay (ELISA) was used to measure the levels of IL-6 and TNF. Paw withdrawal mechanical threshold (PWMT) and paw withdrawal thermal latency (PWTL) were examined.

RESULTS

The expression levels of TRPV1 and CDK5 were found to be upregulated not only in the in vivo CCI model but also in the in vitro lipopolysaccharide (LPS) treatment cell model as well. CDK5 was observed to phosphorylate TRPV1 at T406, prompting the translocation of TRPV1 to the cell membrane and consequent augmentation of cellular excitability. Notably, CDK5 was found to directly bind to TRPV1, and the binding region was localized within the 1-390 amino acid sequence of TRPV1. According to database predictions, miR-142-5p, identified as a shared upstream molecule of TRPV1 and CDK5, exhibited downregulation following induction by NP. MiR-142-5p was shown to simultaneously bind to the mRNA of CDK5 and TRPV1, thereby inhibiting their expression. After LPS treatment, it was observed that pri-miR-142 expression increased, while pre-miR-142 and miR-142-5p expression decreased, suggesting inhibition of the maturation process of pri-miR-142. In addition, the overall level of m6A and in particular the pri-miR-142 m6A modification increased upon LPS treatment. Knockdown of METTL14 led to decreased pri-miR-124 expression, increased pre-miR-124 expression, and enhanced mature miR-142-5p expression, indicating the relief of miR-142-5p maturation repression. The in vivo results indicated that miR-142-5p negatively regulated the expression of CDK5 and TRPV1, suppressed the expression of inflammatory factors IL-6 and TNF, and improved the PWMT and PWTL.

CONCLUSIONS

In this study, we perform a thorough investigation to examine the effects of CDK5 and TRPV1 on NP, elucidating their binding relationship and the impact of CDK5 on the membrane transport of TRPV1. Notably, our findings reveal that miR-142-5p, acting as a crucial upstream molecule, exhibits inhibitory effects on the expression of both CDK5 and TRPV1. Moreover, we observe that METTL14 facilitates the m6A modification of pri-miR-142, thereby impeding the maturation transition of pri-miR-142 and ultimately leading to the downregulation of mature miR-142-5p.

SARM1 in the pathogenesis of immune-related disease

Background

Sterile alpha and toll interleukin receptor motif-containing protein 1 (SARM1) are primarily expressed in the mammalian nervous system, with their presence in neurons being associated with mitochondrial aggregation. SARM1 functions as a mediator of cell death and morphological changes, while also regulating Waller degeneration in nerve fibers and influencing glial cell formation.

Purpose

Recent reports demonstrate SARM1 serves as a connector in the Toll-like receptor (TLR) pathway and plays a role in regulating inflammation during periods of stress such as infection, trauma, and hypoxia. These findings offer new insights into pathogenesis research and the prevention and treatment of neurodegenerative diseases and pathogen infections.

Methods

This review synthesizes recent findings on the immune-related mechanisms of SARM1, emphasizing its roles in inflammation and its functional impact on the nervous system and other bodily systems.

Conclusions

Understanding the multifaceted roles of SARM1 in immune regulation and neuronal health provides novel insights into its involvement in disease pathogenesis. These insights hold promise for advancing research into the prevention and treatment of neurodegenerative diseases and pathogen-induced conditions.

Augustus Waller's foresight realized: SARM1 in peripheral neuropathies

Peripheral neuropathy is a common neurodegenerative condition characterized by numbness, tingling, pain, and weakness that frequently starts in the distal limbs. Arising from multiple etiologies, many peripheral neuropathies exhibit a slowly progressive course due to axon degeneration for which no effective treatments exist. During the past decade, numerous crucial insights into mechanisms of axon degeneration in peripheral neuropathies emerged from experiments involving nerve-cutting procedures, revealing the central role of the SARM1 axon degeneration pathway in both. Here I review commonalities and differences in the role of SARM1 after nerve cut and in several acquired and inherited peripheral neuropathies. This new knowledge now paves the way for the development of therapeutics that directly address root causes of various kinds of neuropathies.

SARM1 regulates pro-inflammatory cytokine expression in human monocytes by NADase-dependent and -independent mechanisms

SARM1 is a Toll-IL-1 receptor (TIR) domain-containing protein with roles in innate immunity and neuronal death in diverse organisms. Unlike other innate immune TIR proteins that function as adaptors for Toll-like receptors (TLRs), SARM1 has NADase activity, and this activity regulates murine neuronal cell death. However, whether human SARM1, and its NADase activity, are involved in innate immune regulation remains unclear. Here, we show that human SARM1 regulates proinflammatory cytokine expression in both an NADase-dependent and -independent manner in monocytes. SARM1 negatively regulated TLR4-dependent TNF mRNA induction independently of its NADase activity. In contrast, SARM1 inhibited IL-1β secretion through both NADase-dependent inhibition of pro-IL-1β expression, and NADase-independent suppression of the NLRP3 inflammasome and hence processing of pro-IL-1β to mature IL-1β. Our study reveals multiple mechanisms whereby SARM1 regulates pro-inflammatory cytokines in human monocytes and shows, compared to other mammalian TIR proteins, a distinct NADase-dependent role for SARM1 in innate immunity.

Proton-sensing ion channels, GPCRs and calcium signaling regulated by them: implications for cancer

Extracellular acidification of tumors is common. Through proton-sensing ion channels or proton-sensing G protein-coupled receptors (GPCRs), tumor cells sense extracellular acidification to stimulate a variety of intracellular signaling pathways including the calcium signaling, which consequently exerts global impacts on tumor cells. Proton-sensing ion channels, and proton-sensing GPCRs have natural advantages as drug targets of anticancer therapy. However, they and the calcium signaling regulated by them attracted limited attention as potential targets of anticancer drugs. In the present review, we discuss the progress in studies on proton-sensing ion channels, and proton-sensing GPCRs, especially emphasizing the effects of calcium signaling activated by them on the characteristics of tumors, including proliferation, migration, invasion, metastasis, drug resistance, angiogenesis. In addition, we review the drugs targeting proton-sensing channels or GPCRs that are currently in clinical trials, as well as the relevant potential drugs for cancer treatments, and discuss their future prospects. The present review aims to elucidate the important role of proton-sensing ion channels, GPCRs and calcium signaling regulated by them in cancer initiation and development. This review will promote the development of drugs targeting proton-sensing channels or GPCRs for cancer treatments, effectively taking their unique advantage as anti-cancer drug targets.

The Role of Cannabidiol in Liver Disease: A Systemic Review

Cannabidiol (CBD), a non-psychoactive phytocannabinoid abundant in Cannabis sativa, has gained considerable attention for its anti-inflammatory, antioxidant, analgesic, and neuroprotective properties. It exhibits the potential to prevent or slow the progression of various diseases, ranging from malignant tumors and viral infections to neurodegenerative disorders and ischemic diseases. Metabolic dysfunction-associated steatotic liver disease (MASLD), formerly known as non-alcoholic fatty liver disease (NAFLD), alcoholic liver disease, and viral hepatitis stand as prominent causes of morbidity and mortality in chronic liver diseases globally. The literature has substantiated CBD's potential therapeutic effects across diverse liver diseases in in vivo and in vitro models. However, the precise mechanism of action remains elusive, and an absence of evidence hinders its translation into clinical practice. This comprehensive review emphasizes the wealth of data linking CBD to liver diseases. Importantly, we delve into a detailed discussion of the receptors through which CBD might exert its effects, including cannabinoid receptors, CB1 and CB2, peroxisome proliferator-activated receptors (PPARs), G protein-coupled receptor 55 (GPR55), transient receptor potential channels (TRPs), and their intricate connections with liver diseases. In conclusion, we address new questions that warrant further investigation in this evolving field.

New concepts drive the development of delivery tools for sustainable treatment of diabetic complications

Diabetic complications, especially diabetic retinopathy, diabetic nephropathy and painful diabetic neuropathy, account for a large portion of patients with diabetes and display rising global prevalence. They are the leading causes of blindness, kidney failure and hypersensitivity to pain caused by diabetes. Current approved therapeutics against the diabetic complications are few and exhibit limited efficacy. The enhanced cell-specificity, stability, biocompatibility, and loading capacity of drugs are essential for the mitigation of diabetic complications. In the article, we have critically discussed the recent studies over the past two years in material sciences and biochemistry. The insightful concepts in these studies drive the development of novel nanoparticles and mesenchymal stem cells-derived extracellular vesicles to meet the need for treatment of diabetic complications. Their underlying biochemical principles, advantages and limitations have been in-depth analyzed. The nanoparticles discussed in the article include double-headed nanodelivery system, nanozyme, ESC-HCM-B system, soft polymer nanostars, tetrahedral DNA nanostructures and hydrogels. They ameliorate the diabetic complication through attenuation of inflammation, apoptosis and restoration of metabolic homeostasis. Moreover, mesenchymal stem cell-derived extracellular vesicles efficiently deliver therapeutic proteins to the retinal cells to suppress the angiogenesis, inflammation, apoptosis and oxidative stress to reverse diabetic retinopathy. Collectively, we provide a critical discussion on the concept, mechanism and therapeutic applicability of new delivery tools to treat these three devastating diabetic complications.

Comprehensive insights into the multifaceted roles of the transient receptor potential vanilloid 1 channel in the digestive system

The transient receptor potential vanilloid (TRPV) channel, a family of calcium transporters comprising six distinct members (TRPV1-6), takes on a paramount role in maintaining intracellular Ca2+ homeostasis in mammalian cells. Notably, TRPV1, among its counterparts, has emerged as the subject of extensive scrutiny, owing to its pervasive presence in diverse cellular, tissue, and organ settings. This ubiquitous distribution underscores its fundamental involvement in the genesis of pain, making it a central focus in pain-related research. However, recent investigations have unveiled that TRPV1's functional significance transcends the realm of pain modulation, extending its influence to encompass a wide spectrum of physiological and pathological processes. The ambit of TRPV1's influence encompasses not only pain responses but also embraces the intricate domains of nervous system disorders, cancer metastasis, as well as afflictions pertaining to the skin and heart. Moreover, compelling evidence now demonstrates that TRPV1 also wields substantial sway in the domain of digestive diseases, further highlighting its versatility and far-reaching impact on human health. Therefore, this comprehensive review endeavors to delve into the multifaceted roles played by TRPV1 in the various organs constituting the digestive system.

Are We Ready to Recommend Capsaicin for Disorders Other Than Neuropathic Pain?

Capsaicin, a lipophilic, volatile compound, is responsible for the pungent properties of chili peppers. In recent years, a significant increase in investigations into its properties has allowed the production of new formulations and the development of tools with biotechnological, diagnostic, and potential therapeutic applications. Most of these studies show beneficial effects, improving antioxidant and anti-inflammatory status, inducing thermogenesis, and reducing white adipose tissue. Other mechanisms, including reducing food intake and improving intestinal dysbiosis, are also described. In this way, the possible clinical application of such compound is expanding every year. This opinion article aims to provide a synthesis of recent findings regarding the mechanisms by which capsaicin participates in the control of non-communicable diseases such as obesity, diabetes, and dyslipidemia.