Pterostilbene, a Bioactive Component of Blueberries, Alleviates Renal Interstitial Fibrosis by Inhibiting Macrophage-Myofibroblast Transition

Advances in macrophage-myofibroblast transformation in fibrotic diseases

Macrophage-myofibroblast transformation (MMT) has emerged as a discovery in the field of fibrotic disease research. MMT is the process by which macrophages differentiate into myofibroblasts, leading to organ fibrosis following organ damage and playing an important role in fibrosis formation and progression. Recently, many new advances have been made in studying the mechanisms of MMT occurrence in fibrotic diseases. This article reviews some critical recent findings on MMT, including the origin of MMT in myofibroblasts, the specific mechanisms by which MMT develops, and the mechanisms and effects of MMT in the kidneys, lungs, heart, retina, and other fibrosis. By summarizing the latest research related to MMT, this paper provides a theoretical basis for elucidating the mechanisms of fibrosis in various organs and developing effective therapeutic targets for fibrotic diseases.

Novel glucomannan-like polysaccharide from Lycium barbarum L. ameliorates renal fibrosis via blocking macrophage-to-myofibroblasts transition

The macrophage to myofibroblasts transition (MMT) has been reported as a newly key target in renal fibrosis. Lycium barbarum L. is a traditional Chinese medicine for improving renal function, in which its polysaccharides (LBPs) are the mainly active components. However, whether the role of LBPs in treating renal fibrosis is related to MMT process remain unclear. The purpose of this study was to explore the relationship between the regulating effect on MMT process and the anti-fibrotic effect of LBPs. Initially, small molecular weight LBPs fractions (LBP-S) were firstly isolated via Sephadex G-100 column. Then, the potent inhibitory effect of LBP-S on MMT process was revealed on bone marrow-derived macrophages (BMDM) model induced by TGF-β. Subsequently, the chemical structure of LBP-S was elucidated through monosaccharide, methylation and NMR spectrum analysis. In vivo biodistribution characteristics studies demonstrated that LBP-S exhibited effectively accumulation in kidney via intraperitoneal administration. Finally, LBP-S showed a satisfactory anti-renal fibrotic effect on unilateral ureteral obstruction operation (UUO) mice, which was significantly reduced following macrophage depletion. Overall, our findings indicated that LPB-S could alleviate renal fibrosis through regulating MMT process and providing new candidate agents for chronic kidney disease (CKD) related fibrosis treatment.

Exploring unconventional targets in myofibroblast transdifferentiation outside classical TGF-β signaling in renal fibrosis

We propose that the key initiators of renal fibrosis are myofibroblasts which originate from four predominant sources-fibroblasts, pericytes, endothelial cells and macrophages. Increased accumulation of renal interstitial myofibroblasts correlates with an increase in collagen, fibrillar proteins, and fibrosis severity. The canonical TGF-β pathway, signaling via Smad proteins, is the central molecular hub that initiates these cellular transformations. However, directly targeting these classical pathway molecules has proven challenging due their integral roles in metabolic process, and/or non-sustainable effects involving compensatory cross-talk with TGF-β. This review explores recently discovered alternative molecular targets that drive transdifferentiation into myofibroblasts. Discovering targets outside of the classical TGF-β/Smad pathway is crucial for advancing antifibrotic therapies, and strategically targeting the development of myofibroblasts offers a promising approach to control excessive extracellular matrix deposition and impede fibrosis progression.

Integrative transcriptomic and proteomic profile revealed inhibition of oxidative phosphorylation and peroxisomes during renal interstitial fibrosis

Effective therapies of chronic kidney disease (CKD) are lacking due to the unclear molecular pathogenesis. Previous single omics-studies have described potential molecular regulation mechanism of CKD only at the level of transcription or translation. Therefore, this study generated an integrated transcriptomic and proteomic profile to provide deep insights into the continuous transcription-translation process during CKD. The comprehensive datasets identified 14,948 transcripts and 6423 proteins, 233 up-regulated and 364 down-regulated common differentially expressed genes of transcriptome and proteome were selected to further combined bioinformatics analysis. The obtained results revealed reactive oxygen species (ROS) metabolism and antioxidant system due to imbalance of mitochondria and peroxisomes were significantly repressed in CKD. Overall, this study presents a valuable multi-omics analysis that sheds light on the molecular mechanisms underlying CKD. SIGNIFICANCE: Chronic kidney disease (CKD) is a progressive and irreversible condition that results in abnormal kidney function and structure, and is ranked 18th among the leading causes of death globally, leading to a significant societal burden. Hence, there is an urgent need for research to detect new, sensitive, and specific biomarkers. Omics-based studies offer great potential to identify underlying disease mechanisms, aid in clinical diagnosis, and develop novel treatment strategies for CKD. Previous studies have mainly focused on the regulation of gene expression or protein synthesis in CKD, thereby compelling us to conduct a meticulous analysis of transcriptomic and proteomic data from the UUO mouse model. Here, we have performed a unified analysis of CKD model by integrating transcriptomes and protein suites for the first time. Our study contributes to a deeper understanding of the pathogenesis of CKD and provides a basis for subsequent disease management and drug development.

Pterostilbene: a potential therapeutic agent for fibrotic diseases

Fibrosis is a prevailing pathology in chronic diseases and accounts for 45% of deaths in developed countries. This condition is primarily identified by the transformation of fibroblasts into myofibroblasts and the overproduction of extracellular matrix (ECM) by myofibroblasts. Pterostilbene (PTS) is a natural analogue of resveratrol and is most commonly found in blueberries. Research has shown that PTS exerts a wide range of pharmacological effects, such as antioxidant, anti-inflammatory, and anticancer effects. As a result, PTS has the potential to prevent and cure numerous diseases. Emerging evidence has indicated that PTS can alleviate myocardial fibrosis, renal fibrosis, pulmonary fibrosis, hepatic fibrosis, and colon fibrosis via the inhibition of inflammation, oxidative stress, and fibrogenesis effects in vivo and in vitro, and the potential mechanisms are linked to various pathways, including transforming growth factor-β1 (TGF-β1)/small mother against decapentaplegic proteins (Smads) signalling, the reactive oxygen species (ROS)-driven Pitx2c/mir-15b pathway, nuclear factor kappa B (NF-κB) signalling, Kelch-like epichlorohydrin-associated protein-1 (Keap-1)/NF-E2-related factor-2 (Nrf2) cascade, the NLR family pyridine structure domain 3 (NLRP3) pathway, the Janus kinase-2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) pathway, and the Src/STAT3 pathway. In this review, we comprehensively summarize the antifibrotic effects of PTS both in vivo and in vitro and the pharmacological mechanisms, pharmacokinetics, and toxicology of PTS and provide insights into and strategies for exploring promising agents for the treatment of fibrosis.

The occurrence and development mechanisms of esophageal stricture: state of the art review

BACKGROUND

Esophageal strictures significantly impair patient quality of life and present a therapeutic challenge, particularly due to the high recurrence post-ESD/EMR. Current treatments manage symptoms rather than addressing the disease's etiology. This review concentrates on the mechanisms of esophageal stricture formation and recurrence, seeking to highlight areas for potential therapeutic intervention.

METHODS

A literature search was conducted through PUBMED using search terms: esophageal stricture, mucosal resection, submucosal dissection. Relevant articles were identified through manual review with reference lists reviewed for additional articles.

RESULTS

Preclinical studies and data from animal studies suggest that the mechanisms that may lead to esophageal stricture include overdifferentiation of fibroblasts, inflammatory response that is not healed in time, impaired epithelial barrier function, and multimethod factors leading to it. Dysfunction of the epithelial barrier may be the initiating mechanism for esophageal stricture. Achieving perfect in-epithelialization by tissue-engineered fabrication of cell patches has been shown to be effective in the treatment and prevention of esophageal strictures.

CONCLUSION

The development of esophageal stricture involves three stages: structural damage to the esophageal epithelial barrier (EEB), chronic inflammation, and severe fibrosis, in which dysfunction or damage to the EEB is the initiating mechanism leading to esophageal stricture. Re-epithelialization is essential for the treatment and prevention of esophageal stricture. This information will help clinicians or scientists to develop effective techniques to treat esophageal stricture in the future.

Guben Xiezhuo Decoction inhibits M1 polarization through the Raf1/p-Elk1 signaling axis to attenuate renal interstitial fibrosis

ETHNOPHARMACOLOGICAL RELEVANCE

Guben Xiezhuo Decoction (GBXZD) is an herbal compound used to treat chronic kidney disease (CKD) under the guidance of traditional Chinese medicine (TCM). Its main components are Astragalus membranaceus (Fisch.) Bunge, Codonopsis pilosula (Franch.) Nannf., Centella asiatica (L.) Urb., Salvia miltiorrhiza Bunge, Cuscuta chinensis Lam., and Rheum palmatum L.. Clinical studies have shown that it can relieve fatigue, nausea and other symptoms and improve kidney function in patients; however, its specific mechanism of action requires further study.

AIM OF THE STUDY

Renal interstitial fibrosis (RIF) is the ultimate characteristic manifestation of various CKD, that cannot be cured, and appropriate treatments to delay its progression require further exploration. GBXZD, widely used in clinical practice for RIF treatment, can effectively relieve the syndrome in patients with CKD. However, the specific mechanism of action of GBXZD in RIF is unknown and requires further study. This study aimed to explore the specific effects of GBXZD on RIF through the regulation of M1 macrophages.

MATERIALS AND METHODS

An in vivo RIF model was obtained through unilateral ureteral obstruction (UUO), and the Sprague-Dawley (SD) rats were randomly divided into sham operation, UUO, UUO + GBXZD-low dose (GBXZD-L) and UUO + GBXZD-high dose (GBXZD-H) groups. Pathological changes in rat kidney specimens were observed using hematoxylin and eosin (HE) and Masson staining. The expression of collagen I (COL I), fibronectin (FN), α-smooth muscle actin (α-SMA), interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumour necrosis factor-α (TNF-α) was detected using immunohistochemistry, and immunofluorescence was used to detect the expression of CD86 and inducible nitric-oxide synthase (iNOS) in kidney tissue. An in vitro experiment was performed using M1 polarization model in RAW264.7 macrophages induced by lipopolysaccharide (LPS). Cells were divided into control, LPS, LPS + GBXZD-low dose (GBXZD-L) and LPS + GBXZD-high dose (GBXZD-H) groups. The changes in expression of CD86, iNOS, IL-1β, IL-6, and TNF-α were measured using western blotting, flow cytometry, immunofluorescence and enzyme-linked immunosorbent assay (ELISA). We analyzed the action pathway of GBXZD in regulating M1 polarization of macrophages using antibody microarray and verified the results using western blotting.

RESULTS

Histopathological results showed that the UUO group exhibited significant fibrotic injury compared to the sham group. After GBXZD treatment, the degree of kidney injury, RIF, and inflammatory factor expression were lower than those in the UUO group. Compared with LPS-treated cells, the expression of the M1 markers CD86, iNOS, and pathway proteins Raf1 and p-Elk1 was down-regulated in RAW 264.7 cells treated with LPS and GBXZD. The secretion of the inflammatory factors IL-1β, IL-6, and TNF-α in the LPS group was more than that in the control group. However, the levels of these factors were significantly reduced in the GBXZD-H group compared to those in the LPS group.

CONCLUSIONS

This study indicates that GBXZD ameliorates RIF and inhibits the inflammatory response and macrophage M1 polarization by a potential mechanism related to the downregulation of Raf1 and p-Elk1. GBXZD therefore has therapeutic potential value for patients with CKD.

Targeting pathogenic macrophages by the application of SHP-1 agonists reduces inflammation and alleviates pulmonary fibrosis

Idiopathic pulmonary fibrosis is a progressive fibrotic disorder with no cure that is characterized by deterioration of lung function. Current FDA-approved drugs for IPF delay the decline in lung function, but neither reverse fibrosis nor significantly improve overall survival. SHP-1 deficiency results in hyperactive alveolar macrophages accumulating in the lung, which contribute to the induction of pulmonary fibrosis. Herein, we investigated whether employing a SHP-1 agonist ameliorates pulmonary fibrosis in a bleomycin-induced pulmonary fibrosis murine model. Histological examination and micro-computed tomography images showed that SHP-1 agonist treatment alleviates bleomycin-induced pulmonary fibrosis. Reduced alveolar hemorrhage, lung inflammation, and collagen deposition, as well as enhanced alveolar space, lung capacity, and improved overall survival were observed in mice administered the SHP-1 agonist. The percentage of macrophages collected from bronchoalveolar lavage fluid and circulating monocytes in bleomycin-instilled mice were also significantly reduced by SHP-1 agonist treatment, suggesting that the SHP-1 agonist may alleviate pulmonary fibrosis by targeting macrophages and reshaping the immunofibrotic niche. In human monocyte-derived macrophages, SHP-1 agonist treatment downregulated CSF1R expression and inactivated STAT3/NFκB signaling, culminating in inhibited macrophage survival and perturbed macrophage polarization. The expression of pro-fibrotic markers (e.g., MRC1, CD200R1, and FN1) by IL4/IL13-induced M2 macrophages that rely on CSF1R signaling for their fate-determination was restricted by SHP-1 agonist treatment. While M2-derived medium promoted the expression of fibroblast-to-myofibroblast transition markers (e.g., ACTA2 and COL3A1), the application of SHP-1 agonist reversed the transition in a dose-dependent manner. Our report indicates that pharmacological activation of SHP-1 ameliorates pulmonary fibrosis via suppression of CSF1R signaling in macrophages, reduction of pathogenic macrophages, and the inhibition of fibroblast-to-myofibroblast transition. Our study thus identifies SHP-1 as a druggable target for the treatment of IPF, and suggests that the SHP-1 agonist may be developed as an anti-pulmonary fibrosis medication that both suppresses inflammation and restrains fibroblast-to-myofibroblast transition.

The Research Progress of Extraction, Purification and Analysis Methods of Phenolic Compounds from Blueberry: A Comprehensive Review

Blueberry is the source of a variety of bioactive substances, including phenolic compounds, such as anthocyanins, pterostilbene, phenolic acids, etc. Several studies have revealed that polyphenols in blueberry have important bioactivities in maintaining health, such as antioxidant and anti-tumor activities, immune regulation, the prevention of chronic diseases, etc. Therefore, these phenolic compounds in blueberries have been widely used in the field of healthcare, and the extraction, isolation, and purification of phenolic compounds are the prerequisites for their utilization. It is imperative to systematically review the research progress and prospects of phenolic compounds present in blueberries. Herein, the latest progress in the extraction, purification, and analysis of phenolic compounds from blueberries is reviewed, which can in turn provide a foundation for further research and usage of blueberries.

Quercetin Alleviates Pulmonary Fibrosis in Silicotic Mice by Inhibiting Macrophage Transition and TGF-β-Smad2/3 Pathway

Silicosis is a pulmonary disease caused by the inhalation of silica. There is a lack of early and effective prevention, diagnosis, and treatment methods, and addressing silicotic fibrosis is crucial. Quercetin, a flavonoid with anti-carcinogenic, anti-inflammatory, and antiviral properties, is known to have a suppressive effect on fibrosis. The present study aimed to determine the therapeutic effect of quercetin on silicotic mice and macrophage polarity. We found that quercetin suppressed silicosis in mice. It was observed that SiO₂ activated macrophage polarity and the macrophage-to-myofibroblast transition (MMT) by transforming the growth factor-β (TGF-β)-Smad2/3 signaling pathway in silicotic mice and MH-S cells. Quercetin also attenuated the MMT and the TGF-β-Smad2/3 signaling pathway in vivo and in vitro. The present study demonstrated that quercetin is a potential therapeutic agent for silicosis, which acts by regulating macrophage polarity and the MMT through the TGF-β-Smad2/3 signaling pathway.

Blocking connexin 43 and its promotion of ATP release from renal tubular epithelial cells ameliorates renal fibrosis

Whether metabolites derived from injured renal tubular epithelial cells (TECs) participate in renal fibrosis is poorly explored. After TEC injury, various metabolites are released and among the most potent is adenosine triphosphate (ATP), which is released via ATP-permeable channels. In these hemichannels, connexin 43 (Cx43) is the most common member. However, its role in renal interstitial fibrosis (RIF) has not been fully examined. We analyzed renal samples from patients with obstructive nephropathy and mice with unilateral ureteral obstruction (UUO). Cx43-KSP mice were generated to deplete Cx43 in TECs. Through transcriptomics, metabolomics, and single-cell sequencing multi-omics analysis, the relationship among tubular Cx43, ATP, and macrophages in renal fibrosis was explored. The expression of Cx43 in TECs was upregulated in both patients and mice with obstructive nephropathy. Knockdown of Cx43 in TECs or using Cx43-specific inhibitors reduced UUO-induced inflammation and fibrosis in mice. Single-cell RNA sequencing showed that ATP specific receptors, including P2rx4 and P2rx7, were distributed mainly on macrophages. We found that P2rx4- or P2rx7-positive macrophages underwent pyroptosis after UUO, and in vitro ATP directly induced pyroptosis by macrophages. The administration of P2 receptor or P2X7 receptor blockers to UUO mice inhibited macrophage pyroptosis and demonstrated a similar degree of renoprotection as Cx43 genetic depletion. Further, we found that GAP 26 (a Cx43 hemichannel inhibitor) and A-839977 (an inhibitor of the pyroptosis receptor) alleviated UUO-induced fibrosis, while BzATP (the agonist of pyroptosis receptor) exacerbated fibrosis. Single-cell sequencing demonstrated that the pyroptotic macrophages upregulated the release of CXCL10, which activated intrarenal fibroblasts. Cx43 mediates the release of ATP from TECs during renal injury, inducing peritubular macrophage pyroptosis, which subsequently leads to the release of CXCL10 and activation of intrarenal fibroblasts and acceleration of renal fibrosis.

Therapeutic and delivery strategies of phytoconstituents for renal fibrosis

Chronic kidney disease (CKD) is one of the most common diseases endangering human health and life. By 2030, 14 per 100,000 people may die from CKD. Renal fibrosis (RF) is an important intermediate link and the final pathological change during CKD progression to the terminal stage. Therefore, identifying safe and effective treatment methods for RF has become an important goal. In 2018, the World Health Organization introduced traditional Chinese medicine into its effective global medical program. Various phytoconstituents that affect the RF process have been extracted from different plants. Here, we review the potential therapeutic capabilities of active phytoconstituents in RF treatment and discuss how phytoconstituents can be structurally modified or combined with other ingredients to enhance efficiency and reduce toxicity. We also summarize phytoconstituent delivery strategies to overcome renal barriers and improve bioavailability and targeting.

Thioredoxin-interacting protein (TXNIP) as a target for Alzheimer's disease: flavonoids and phenols

Alzheimer's disease (AD) is a neurodegenerative disease characterized by amyloid plaques and tangles that have become the fifth leading cause of death worldwide. Previous studies have found that thioredoxin interacting protein (TXNIP) expression was increased during the development of AD neurons. TXNIP separates from the TXNIP-thioredoxin complex, and the TXNIP-NLRP3 complex assembles ASC and pro-caspase-1 to form the NLRP3 inflammasome, which triggers AD inflammation and apoptosis. CB-dock was used to explore whether 21 natural flavonoids and phenols target TXNIP based on references. Docking results showed that rutin, puerarin, baicalin, luteolin and quercetin are the most potent TXNIP inhibitors, and among them, rutin as the most effective flavonoid. And rosmarinic acid is the most potent TXNIP inhibitor of phenols. These phytochemicals could be helpful to find the lead compounds in designing and developing novel agents for Alzheimer's disease.

Monocyte and macrophage derived myofibroblasts: Is it fate? A review of the current evidence

Since the discovery of the myofibroblast over 50 years ago, much has been learned about its role in wound healing and fibrosis. Its origin, however, remains controversial, with a number of progenitor cells being proposed. Macrophage-myofibroblast transition (MMT) is a recent term coined in 2014 that describes the mechanism through which macrophages, derived from circulating monocytes originating in the bone marrow, transformed into myofibroblasts and contributed to kidney fibrosis. Over the past years, several studies have confirmed the existence of MMT in various systems, suggesting that MMT could potentially occur in all fibrotic conditions and constitute a reasonable therapeutic target to prevent progressive fibrotic disease. In this perspective, we examined recent evidence supporting the notion of MMT in both human disease and experimental models across organ systems. Mechanistic insight from these studies and information from in vitro studies is provided. The findings substantiating plausible MMT showcased the co-expression of macrophage and myofibroblast markers, including CD68 or F4/80 (macrophage) and α-SMA (myofibroblast), in fibroblast-like cells. Furthermore, fate-mapping experiments in murine models exhibiting myeloid-derived myofibroblasts in the tissue further provide direct evidence for MMT. Additionally, we provide some evidence from single cell RNA sequencing experiments confirmed by fluorescent in situ hybridisation studies, showing monocyte/macrophage and myofibroblast markers co-expressed in lung tissue from patients with fibrotic lung disease. In conclusion, MMT is likely a significant contributor to myofibroblast formation in wound healing and fibrotic disease across organ systems. Circulating precursors including monocytes and the molecular mechanisms governing MMT could constitute valid targets and provide insight for the development of novel antifibrotic therapies; however, further understanding of these processes is warranted.