Folate and macrophage folate receptor-β in idiopathic pulmonary fibrosis disease: the potential therapeutic target?

Developmental toxicity and metabolomics analyses of zebrafish (Danio rerio) embryos exposed to Fenoxaprop-p-ethyl

Fenoxaprop-p-ethyl (FEN) is an aryloxy phenoxy propionate herbicide that has been widely used in paddy fields. Previous studies have indicated that FEN is highly toxic to aquatic organisms, but little is known about the developmental effects of FEN. This study investigated acute and developmental toxicity, malondialdehyde (MDA) levels, superoxide dismutase (SOD) and catalase (CAT) activities, and metabolomic analyses in zebrafish embryos after 96 h of exposure. FEN exhibited high acute toxicity to zebrafish embryos and larvae. Exposure to FEN could reduce heartbeat and hatching rates and increase malformation rates in embryos. Oxidative damage was also caused in embryos. The results of metabolomics analysis showed that 102 differentially abundant metabolites were found in zebrafish embryos in the 0.05 mg/L FEN treatment group, and 60 differentially abundant metabolites were found in the 0.20 mg/L FEN treatment group. These differentially abundant metabolites mainly belonged to 9 metabolic pathways, of which folate pathways and ABC transport protein pathways had the greatest impact. These results suggested that FEN induced high acute and developmental toxicity in zebrafish embryos.

Genetic association analysis of dietary intake and idiopathic pulmonary fibrosis: a two-sample mendelian randomization study

BACKGROUND

IPF is a complex lung disease whose aetiology is not fully understood, but diet may have an impact on its development and progression. Therefore, we investigated the potential causal connection between dietary intake and IPF through TSMR to offer insights for early disease prevention recommendations.

METHODS

The study incorporated 29 dietary exposure factors, oily fish intake, bacon intake, processed meat intake, poultry intake, beef intake, pork intake, lamb/mutton intake, non-oily fish intake, fresh fruit intake, cooked vegetable intake, baked bean intake, fresh tomato intake, tinned tomato intake, salad/raw vegetable intake, Fresh fruit intake, coffee intake, tea intake, water intake, red wine intake, average weekly beer plus cider intake, alcoholic drinks per week, cereal intake, bread intake, whole-wheat intake, whole-wheat cereal intake, cheese intake, yogurt intake, salt added to food and whole egg intake. The study explored the causal link between diet and IPF using TSMR analysis, predominantly the IVW method, and performed sensitivity analyses to validate the results.

RESULT

The study revealed that consuming oily fish, yogurt, and dried fruits had a protective effect against IPF, whereas the consumption of alcoholic beverages and beef was linked to an increased risk of IPF.

CONCLUSION

In this MR study, it was discovered that the consumption of oily fish, yogurt, and dried fruits exhibited a protective effect against IPF, whereas the intake of alcoholic beverages and beef was associated with an elevated risk of IPF. These findings underscore the significance of making informed and timely dietary decisions in IPF prevention.

Targeted liposomes for macrophages-mediated pulmonary fibrosis therapy

Pulmonary fibrosis (PF) is a horrible lung disease that causes pulmonary ventilation dysfunction and respiratory failure, severely impacting sufferers' physical and mental health. Existing drugs can only partially control the condition and are prone to toxic side effects. Anti-inflammatory treatment is the committed step to alleviate PF. Celastrol (CLT) has significant anti-inflammatory effects and can reverse M1-type transformation of macrophages. In this study, we have developed liposomes loaded with CLT, modified with folate (FA), designated FA-CLT-Lips, which facilitate drug delivery by targeting macrophages. FA-CLT-Lips were shown to be more readily absorbed by macrophages in vitro and to encourage the transition of M1 macrophages into M2 macrophages. In addition, FA-CLT-Lips can inhibit the phosphorylation of Smad2/3, effectively reducing the deposition of extracellular matrix (ECM) and the production of inflammatory factors. This showed that FA-CLT-Lips can ameliorate early lung fibrosis by lowering inflammation. In vivo studies have shown that FA-CLT-Lips accumulate in lung tissue to better attenuate lung injury and collagen deposition, with less toxicity compared to free CLT. In summary, FA receptor-targeting liposomes loaded with CLT provide a secure and reliable PF therapy.

In Vivo Comparative Study of Radioiodinated Folate Receptor Targeting Albumin Probes for Atherosclerosis Plaque Imaging

The objective of this study is to compare a series of albumin-based folate radiotracers for the potential imaging of folate receptor (FR) positive macrophages in advanced atherosclerotic plaques. Diversified radioiodinated FR-targeting albumin-binding probes ([131I]IBAbHF, [131I]IBNHF, and [131I]HF) were developed through various strategies. Among the three radiotracers, [131I]IBAbHF and [131I]IBNHF showed excellent in vitro stability (>98%) in saline and PBS 7.4 for 24 h. Also, good stability of [131I]IBNHF in mouse serum albumin was monitored using an HSA ELISA kit. The experiments in Raw264.7 macrophages activated by ox-LDL confirmed the specificity of tracers for FR-β. Biodistribution studies of radiotracers were performed to verify the prolonged blood half-life. Prolonged blood half-lives of [131I]IBAbHF, [131I]HF, and [131I]IBNHF were 17.26 ± 4.29, 6.33 ± 2.64, and 5.50 ± 1.26 h, respectively. SPECT-CT imaging of ApoE-/- mice at different stages was performed to evaluate the progression and monitor the prognosis of AS. Evident [131I]IBNHF uptake in atherosclerotic lesions could be observed along with a low background signal. In summary, we demonstrated a proof-of-concept of albumin-based radioligands for FR-targeting atherosclerosis imaging and found that different incorporation of radioiodinated groups resulted in different pharmacokinetic properties. Among these candidate compounds, [131I]IBNHF would be a satisfactory radiotracer for SPECT imaging of atherosclerosis.

Mitochondrial folate metabolism-mediated α-linolenic acid exhaustion masks liver fibrosis resolution

Sustainable TGF-β1 signaling drives organ fibrogenesis. However, the cellular adaptation to maintain TGF-β1 signaling remains unclear. In this study, we revealed that dietary folate restriction promoted the resolution of liver fibrosis in mice with nonalcoholic steatohepatitis (NASH). In activated hepatic stellate cells (HSCs), folate shifted toward mitochondrial metabolism to sustain TGF-β1 signaling. Mechanistically, nontargeted metabolomics screening identified that α-linolenic acid (ALA) is exhausted by mitochondrial folate metabolism in activated HSCs. Knocking down serine hydroxymethyltransferase 2 (SHMT2) increases the bioconversion of ALA to docosahexaenoic acid (DHA) which inhibits TGF-β1 signaling. Finally, blocking mitochondrial folate metabolism promoted liver fibrosis resolution in NASH mice. In conclusion, mitochondrial folate metabolism/ALA exhaustion/TGF-βR1 reproduction is a feedforward signaling to sustain profibrotic TGF-β1 signaling and targeting mitochondrial folate metabolism is a promising strategy to enforce liver fibrosis resolution.

Mitochondrial folate pathway regulates myofibroblast differentiation and silica-induced pulmonary fibrosis

BACKGROUND

Silica-induced pulmonary fibrosis (silicosis) is a diffuse interstitial fibrotic disease characterized by the massive deposition of extracellular matrix in lung tissue. Fibroblast to myofibroblast differentiation is crucial for the disease progression. Inhibiting myofibroblast differentiation may be an effective way for pulmonary fibrosis treatment.

METHODS

The experiments were conducted in TGF-β treated human lung fibroblasts to induce myofibroblast differentiation in vitro and silica treated mice to induce pulmonary fibrosis in vivo.

RESULTS

By quantitative mass spectrometry, we revealed that proteins involved in mitochondrial folate metabolism were specifically upregulated during myofibroblast differentiation following TGF-β stimulation. The expression level of proteins in mitochondrial folate pathway, MTHFD2 and SLC25A32, negatively regulated myofibroblast differentiation. Moreover, plasma folate concentration was significantly reduced in patients and mice with silicosis. Folate supplementation elevated the expression of MTHFD2 and SLC25A32, alleviated oxidative stress and effectively suppressed myofibroblast differentiation and silica-induced pulmonary fibrosis in mice.

CONCLUSION

Our study suggests that mitochondrial folate pathway regulates myofibroblast differentiation and could serve as a potential target for ameliorating silica-induced pulmonary fibrosis.

Machine learning-based prediction of candidate gene biomarkers correlated with immune infiltration in patients with idiopathic pulmonary fibrosis

Objective

This study aimed to identify candidate gene biomarkers associated with immune infiltration in idiopathic pulmonary fibrosis (IPF) based on machine learning algorithms.

Methods

Microarray datasets of IPF were extracted from the Gene Expression Omnibus (GEO) database to screen for differentially expressed genes (DEGs). The DEGs were subjected to enrichment analysis, and two machine learning algorithms were used to identify candidate genes associated with IPF. These genes were verified in a validation cohort from the GEO database. Receiver operating characteristic (ROC) curves were plotted to assess the predictive value of the IPF-associated genes. The cell-type identification by estimating relative subsets of RNA transcripts (CIBERSORT) algorithm was used to evaluate the proportion of immune cells in IPF and normal tissues. Additionally, the correlation between the expression of IPF-associated genes and the infiltration levels of immune cells was examined.

Results

A total of 302 upregulated and 192 downregulated genes were identified. Functional annotation, pathway enrichment, Disease Ontology and gene set enrichment analyses revealed that the DEGs were related to the extracellular matrix and immune responses. COL3A1, CDH3, CEBPD, and GPIHBP1 were identified as candidate biomarkers using machine learning algorithms, and their predictive value was verified in a validation cohort. Additionally, ROC analysis revealed that the four genes had high predictive accuracy. The infiltration levels of plasma cells, M0 macrophages and resting dendritic cells were higher and those of resting natural killer (NK) cells, M1 macrophages and eosinophils were lower in the lung tissues of patients with IPF than in those of healthy individuals. The expression of the abovementioned genes was correlated with the infiltration levels of plasma cells, M0 macrophages and eosinophils.

Conclusion

COL3A1, CDH3, CEBPD, and GPIHBP1 are candidate biomarkers of IPF. Plasma cells, M0 macrophages and eosinophils may be involved in the development of IPF and may serve as immunotherapeutic targets in IPF.

Renal Proximal Tubular Cells: A New Site for Targeted Delivery Therapy of Diabetic Kidney Disease

Diabetic kidney disease (DKD) is a major complication of diabetes mellitus (DM) and the leading cause of end-stage kidney disease (ESKD) worldwide. A significant number of drugs have been clinically investigated for the treatment of DKD. However, a large proportion of patients still develop end-stage kidney disease unstoppably. As a result, new effective therapies are urgently needed to slow down the progression of DKD. Recently, there is increasing evidence that targeted drug delivery strategies such as large molecule carriers, small molecule prodrugs, and nanoparticles can improve drug efficacy and reduce adverse side effects. There is no doubt that targeted drug delivery strategies have epoch-making significance and great application prospects for the treatment of DKD. In addition, the proximal tubule plays a very critical role in the progression of DKD. Consequently, the purpose of this paper is to summarize the current understanding of proximal tubule cell-targeted therapy, screen for optimal targeting strategies, and find new therapeutic approaches for the treatment of DKD.

Niclosamide targets the dynamic progression of macrophages for the resolution of endometriosis in a mouse model

Due to the vital roles of macrophages in the pathogenesis of endometriosis, targeting macrophages could be a promising therapeutic direction. Here, we investigated the efficacy of niclosamide for the resolution of a perturbed microenvironment caused by dysregulated macrophages in a mouse model of endometriosis. Single-cell transcriptomic analysis revealed the heterogeneity of macrophages including three intermediate subtypes with sharing characteristics of traditional “small” or “large” peritoneal macrophages (SPMs and LPMs) in the peritoneal cavity. Endometriosis-like lesions (ELL) enhanced the differentiation of recruited macrophages, promoted the replenishment of resident LPMs, and increased the ablation of embryo-derived LPMs, which were stepwise suppressed by niclosamide. In addition, niclosamide restored intercellular communications between macrophages and B cells. Therefore, niclosamide rescued the perturbed microenvironment in endometriosis through its fine regulations on the dynamic progression of macrophages. Validation of similar macrophage pathogenesis in patients will further promote the clinical usage of niclosamide for endometriosis treatment.

An 8-ferroptosis-related genes signature from Bronchoalveolar Lavage Fluid for prognosis in patients with idiopathic pulmonary fibrosis

Background

With the rapid advances of genetic and genomic technologies, the pathophysiological mechanisms of idiopathic pulmonary fibrosis (IPF) were gradually becoming clear, however, the prognosis of IPF was still poor. This study aimed to systematically explore the ferroptosis-related genes model associated with prognosis in IPF patients.

Methods

Datasets were collected from the Gene Expression Omnibus (GEO). The least absolute shrinkage and selection operator (LASSO) Cox regression analysis was applied to create a multi-gene predicted model from patients with IPF in the Freiburg cohort of the GSE70866 dataset. The Siena cohort and the Leuven cohort were used for validation.

Results

Nineteen differentially expressed genes (DEGs) between the patients with IPF and control were associated with poor prognosis based on the univariate Cox regression analysis (all P < 0.05). According to the median value of the risk score derived from an 8-ferroptosis-related genes signature, the three cohorts’ patients were stratified into two risk groups. Prognosis of high-risk group (high risk score) was significantly poorer compared with low-risk group in the three cohorts. According to multivariate Cox regression analyses, the risk score was an independently predictor for poor prognosis in the three cohorts. Receiver operating characteristic (ROC) curve analysis and decision curve analysis (DCA) confirmed the signature's predictive value in the three cohorts. According to functional analysis, inflammation- and immune-related pathways and biological process could participate in the progression of IPF.

Conclusions

These results imply that the 8-ferroptosis-related genes signature in the bronchoalveolar lavage samples might be an effective model to predict the poor prognosis of IPF.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-021-01799-7.

Targeting monocytes/macrophages in fibrosis and cancer diseases: Therapeutic approaches

Over almost 140 years since their identification, the knowledge about macrophages has unbelievably evolved. The 'big eaters' from being thought of as simple phagocytic cells have been recognized as master regulators in immunity, homeostasis, healing/repair and organ development. Long considered to originate exclusively from bone marrow-derived circulating monocytes, macrophages have been also demonstrated to be the first immune cells colonizing tissues in the developing embryo and persisting in adult life by self-renewal, as long-lived tissue resident macrophages. Therefore, heterogeneous populations of macrophages with different ontogeny and functions co-exist in tissues. Macrophages act as sentinels of homeostasis and are intrinsically programmed to lead the wound healing and repair processes that occur after injury. However, in certain pathological circumstances macrophages get dysfunctional, and impaired or aberrant macrophage activities become key features of diseases. For instance, in both fibrosis and cancer, that have been defined 'wounds that do not heal', dysfunctional monocyte-derived macrophages overall play a key detrimental role. On the other hand, due to their plasticity these cells can be 're-educated' and exert anti-fibrotic and anti-cancer functions. Therefore macrophages represent an important therapeutic target in both fibrosis and cancer diseases. The current review will illustrate new insights into the role of monocytes/macrophages in these devastating diseases and summarize new therapeutic strategies and applications of macrophage-targeted drug development in their clinical setting.

Properties and reactivity of the folic acid and folate photoproduct 6-formylpterin

Folates (vitamin B9) are essential components of our diet and our gut microbiota. They are omnipresent in our cells and blood. Folates are necessary for DNA synthesis, methylation, and other vital bioprocesses. Folic acid (FA), as the synthetic form of folates, is largely found in supplements and fortified foods. FA and folate drugs are also extensively used as therapeutics. Therefore, we are continuously exposed to the pterin derivatives, and their photo-degradation products, such as 6-formylpterin (6-FPT) and pterin-6-carboxylic acid. During ultraviolet radiation, these two photolytic products generate reactive oxygen species (ROS) responsible for the cellular oxidative stress. 6-FPT can exhibit variable pro/anti-oxidative roles depending on the cell type and its environment (acting as a cell protector in normal cells, or as an enhancer of drug-induced cell death in cancer cells). The ROS-modulating capacity of 6-FPT is well-known, whereas its intrinsic reactivity has been much less investigated. Here, we have reviewed the properties of 6-FPT and highlighted its capacity to form covalent adducts with the ROS-scavenging drug edaravone (used to treat stroke and amyotrophic lateral sclerosis) as well as its implication in immune surveillance. 6-FPT and its analogue acetyl-6-FPT function as small molecule antigens, recognized by the major histocompatibility complex-related class I-like molecule, MR1, for presentation to mucosal-associated invariant T (MAIT) cells. As modulators of the MR1/MAIT machinery, 6-FPT derivatives could play a significant immuno-regulatory role in different diseases. This brief review shed light on the multiple properties and cellular activities of 6-FPT, well beyond its primary ROS-generating activity.