The role of altered lipid composition and distribution in liver fibrosis revealed by multimodal nonlinear optical microscopy

Prolonged local retention of vancomycin achieved by a multivesicular liposomes in thermoresponsive gel system for the prevention and treatment of intervertebral disc infection

The therapeutic efficacy of intervertebral disc (IVD) infections treated with intravenous vancomycin (VCM) is often limited by inadequate blood supply to the IVD. In this study, we developed a localized and sustained-release drug delivery system for the intradiscal administration of VCM. First, VCM-loaded multivesicular liposomes (VCM-MVLs) were prepared using a two-step emulsification process, and we investigated the effects of the preparation process and formulation composition on the quality of the MVLs. The prepared MVLs exhibited an encapsulation efficiency of 92.08 ± 6.44 %, a particle size of 30.35 μm, and a sustained release over 12 days. Subsequently, VCM-MVLs were incorporated with PLGA-PEG-PLGA (PPP) to create a thermosensitive hydrogel composite formulation (VCM-MVL-PPP), which demonstrated a gelling temperature of 28.4°C and exhibited prolonged sustained release over 20 days. The antimicrobial activity of VCM-MVL-PPP was maintained for an extended duration of 21 days. Additionally, the VCM-MVL-PPP demonstrated an optimal retention capacity of 14 days in the in vivo retention assay. In vivo safety results confirmed the high biocompatibility and negligible toxicity of the formulation. In conclusion, the presence of PPP as a secondary release barrier for the drug released from MVLs allowed VCM-MVL-PPP to exhibit prolonged drug release and retention in the IVDs compared to VCM-MVLs. Our findings provide a valuable reference for peptide delivery and the treatment of disc infections.

Illuminating life processes by vibrational probes

Vibration of chemical bonds can serve as imaging contrast. Vibrational probes, synergized with major advances in chemical bond imaging instruments, have recently flourished and proven valuable in illuminating life processes. Here, we review how the development of vibrational probes with optimal biocompatibility, enhanced sensitivity, multichromatic colors and diverse functionality has extended chemical bond imaging beyond the prevalent label-free paradigm into various novel applications such as imaging metabolites, metabolic imaging, drug imaging, super-multiplex imaging, vibrational profiling and vibrational sensing. These advancements in vibrational probes have greatly facilitated understanding living systems, a new field of vibrational chemical biology.

Stimulated Raman Scattering Microscopy Facilitates the Discovery of Diacylglycerol O-Acyltransferase 2 as a Target to Enhance Iodine Uptake in Papillary Thyroid Carcinoma

Radioactive 131I therapy is a primary treatment for papillary thyroid carcinoma (PTC), with approximately 30% of patients developing iodine-refractory disease. There is an urgent clinical need to improve iodine uptake in PTC. Previous research suggested a connection between triglyceride (TG) accumulation and decreased iodine uptake in benign thyroid cells. Notably, TG accumulation has been found to be a marker of aggressive human PTC. Therefore, it is crucial to elucidate whether TG accumulation affects iodine uptake in PTC, which may lead to a new way for enhancement of iodine uptake. Here, by combining stimulated Raman scattering (SRS) microscopy and deuterated Raman tags, we first quantitatively analyzed the level of TG and its source in the K1 cell with low iodine uptake and the TPC-1 cell with high iodine uptake. It was found that K1 cells had significantly greater TG accumulation than TPC-1 cells, primarily due to an increased exogenous uptake of fatty acids. Further RNA-seq transcriptome experiments revealed that the underlying mechanism could be upregulation of lipid biosynthesis, uptake, and transport-related genes, along with down-regulation of fatty acid β-oxidation and lipolysis-related genes in K1 cells. Among the upregulated lipid biosynthesis genes, diacylglycerol O-acyltransferase 2 (DGAT2) is of great importance as the rate-limiting enzyme in TG biosynthesis. Notably, the inhibition of DGAT2 led to a significant increase in the expression of iodine uptake-related proteins, namely, sodium iodide symporter (NIS) and thyroglobulin (Tg), in K1 cells. Further Gene Ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses unraveled that DGAT2 inhibition could enhance thyroid hormone synthesis, for which iodine is an essential raw material, by alleviating endoplasmic reticulum stress and upregulating the pathways related to protein glycosylation and transmembrane transport. In summary, our study has shown that SRS microscopy facilitates the discovery of DGAT2 as a potential target to enhance iodine uptake in PTC, which holds promise for improving treatment outcome of iodine-refractory PTC.

Impact of Tenofovir Alafenamide on Lipid Profiles in Chronic Hepatitis B Patients: Systematic Review and Meta-Analysis

Tenofovir alafenamide (TAF) is widely used for chronic hepatitis B (CHB) treatment due to its improved renal and bone safety compared to tenofovir disoproxil fumarate (TDF). However, emerging evidence suggests that TAF may adversely affect lipid metabolism, raising concerns about potential cardiovascular risks. A systematic review and meta-analysis following PRISMA guidelines was conducted. Studies comparing lipid profile changes in CHB patients receiving TAF, TDF, or entecavir (ETV) were retrieved from PubMed, Cochrane, and Embase. Primary outcomes included changes in total cholesterol (TC), triglycerides (TG), low-density lipoprotein (LDL), and high-density lipoprotein (HDL). Sensitivity analyses were performed to assess potential confounders, including lipid-lowering therapy. Trial sequential analysis (TSA) was used to evaluate the sufficiency of evidence. A total of 23 studies (5 RCTs, 18 observational) were included. Observational data showed significant increases in TC (MD = 10.74 mg/dL), TG (MD = 11.56 mg/dL), LDL (MD = 3.08 mg/dL), and HDL (MD = 7.51 mg/dL) with TAF versus TDF. Meta-analysis of RCTs confirmed these findings, showing TC (MD = 18.28 mg/dL), LDL (MD = 13.09 mg/dL), and HDL (MD = 4.95 mg/dL) elevations. TAF is associated with increased lipid levels, likely due to the loss of TDF's lipid-lowering effect. While its cardiovascular risk remains uncertain, clinicians should monitor lipid profiles in CHB patients on TAF, particularly those at high cardiovascular risk.

PPARs: modulating lipotoxicity and thus inhibiting fibrosis

Peroxisome proliferator-activated receptors (PPARs) belong to the nuclear hormone receptor family of ligand-activated receptors and are known for their roles as key factors in the regulation of lipid metabolism. In the more than three decades since their discovery, most reports on PPARs have focused on their roles in lipid metabolism, and a portion of the new research has also focused on the relationship between PPARs and fibrosis. Interestingly, lipid metabolism disorders and fibrosis are also inextricably linked. This implies that PPARs, lipid metabolism and fibrosis are interrelated. On this basis, we have summarized the molecular mechanisms of PPARs regulating fibrosis through lipid metabolism and PPARγ directly regulating fibrosis, and pointed out the contradictions and enigmas that need to be further explored in the processes of PPARs regulating lipid metabolism and fibrosis. The aim of the present review is to provide new ideas for PPARs for the treatment of lipid metabolism disorders and fibrosis.

Total saponin extracts of Pseudostellaria heterophylla ameliorates meibomian gland dysfunction through SCD1/SPT1/ceramide axis

ETHNOPHARMACOLOGICAL RELEVANCE

Pseudostellaria heterophylla (Tài Zǐ Shēn, TZS) is a traditional Chinese medicine with spleen and qi benefits. Its immunomodulatory, anti-fatigue, anti-stress, and lipid metabolism regulation effects have been clinically confirmed, but its role in meibomian gland dysfunction (MGD) is still unclear.

AIM OF THE STUDY

This study aims to investigate the effect and mechanism of action of TZS in treating MGD.

MATERIAL AND METHODS

Several therapeutic agents were used to predict MGD treatment using the "Disease-Syndrome-TCM" network mechanism. We then performed a network pharmacology analysis to identify possible targets and pathways for drug treatment of the disease. It was then validated by in vitro experiments. The animal models were taken and analyzed by slit lamp and stereo microscope. HE and ORO staining analysis were then performed. Next, the expressions of key protein indicators were tested by IF, and finally the metabolism of key substances such as lipids and ceramides were detected by SRS imaging.

RESULTS

The "Disease-Syndrome-TCM" network mechanism was used to predict several therapeutic agents for MGD treatment including TZS et al. Network pharmacology analysis revealed that the targets of active components in the total saponins of TZS (PHS) were significantly enriched in the pathways of PPAR and AMPK. Subsequently, seven targets of PHS were identified, which were enriched in signaling pathways associated with lipid metabolism and inflammation. Furthermore, in vivo experiments showed that PHS alleviated meibomian glands (MG) obstruction and atrophy induced by A939, a SCD1 inhibitor. PHS treatment significantly increased PPAR-γ proteins in MGs, contributing to the normal differentiation of acini. Additionally, PHS treatment resulted in a reduction in the number of K10-positive cells, which partially prevented keratinization and abnormal differentiation of acinar cells. TUNEL assay results indicated that PHS mitigated apoptosis in MGs. Detailed exploration using Raman spectroscopy imaging showed that PHS could enhance the expression of SCD1 protein and the unsaturation degree of fatty acids, which in turn downregulated SPT1 protein and endogenous ceramides de novo biosynthesis.

CONCLUSION

This study elucidated the effects of PHS in alleviating MGD and highlighted the pharmacological mechanisms involved, specifically the upregulation of SCD1 and inhibition of de novo ceramides biosynthesis. These findings provided a research basis for advancing its clinical application in MGD treatment.

Unveiling Lipid Metabolic Shifts in Different Stages of Oral Submucous Fibrosis: A New Horizon in Predicting Malignant Transformation

Background

Oral Submucous Fibrosis (OSMF) is a chronic, progressive condition linked to areca nut consumption, with a high potential for malignant transformation into oral squamous cell carcinoma (OSCC). Changes in lipid metabolism have been implicated in cancer biology, yet the relationship between lipid profiles and OSMF progression remains underexplored. This study investigates the alterations in serum lipid parameters across different clinical stages of OSMF and their association with malignant transformation.

Materials and methods

A cross-sectional study was conducted over 69 OSMF patients, divided into five groups (Stage 1 to 3 and Stage 4a, 4b) based on clinical staging. Serum lipid profiles, including total cholesterol (TC), high-density lipoprotein (HDL), low-density lipoprotein (LDL), very low-density lipoprotein (VLDL), and triglycerides (TG), were analyzed. Statistical analysis was performed using ANOVA and Tukey's post hoc test.

Results

Lipid levels (TC, HDL, LDL, VLDL, TG) showed a significant decline from Stage 1 to Stage 4a (p-0.00), followed by a sharp increase in Stage 4b (p-0.00), coinciding with malignant transformation. Particularly, HDL, VLDL, and TG were significantly elevated in Stage 4b compared to earlier stages.

Conclusion

Alterations in lipid metabolism (hypolipidemia) were observed from Stage 1 to 4a, with a marked shift (hyperlipidemia) during malignant transformation (Stage 4b). Increased levels of HDL, VLDL, and TG in advanced OSMF stages suggest their potential as predictive biomarkers for malignancy. Further research is required to elucidate the mechanisms linking lipid metabolism with OSMF progression and malignancy, paving the way for targeted therapeutic strategies.

The interactive role of microRNA and other non-coding RNA in hepatitis B (HBV) associated fibrogenesis

One of the outstanding features of chronic hepatitis B infection (CHB) is its strong association with liver fibrosis. CHB induced inflammation and injury trigger multiple biochemical and physical changes that include the promotion of a wide range of cytokines, chemokines and growth factors that activate hepatic stellate cells (HSCs) CHB induced activation of hepatic stellate cells (HSCs) is regarded as a central event in fibrogenesis to directly promote the synthesis of myofibroblasts and the expression of a range of materials to repair injured liver tissue. Fibrogenesis is modulated by the mainstream epigenetic machinery, as well as by non-coding RNA (ncRNA) that are often referred to as an ancillary epigenetic response to fine tune gene expression. Although extensive research has explained the regulatory role of ncRNA in liver fibrogenesis, most of this research relates to non-CHB etiologies. This review paper outlines the complex interactive regulatory role of microRNA (miRNA) and their interaction with long non-coding RNA (lncRNA), circular RNA (circRNA) and the mainstream epigenetic machinery in CHB induced liver fibrosis. The paper also illustrates some of the difficulties involved in translating candidate ncRNA into approved drugs or diagnostic tools. In conclusion, the important regulatory role of ncRNA in CHB induced liver fibrosis warrants further investigation to exploit their undoubted potential as diagnostic and therapeutic agents.

Ferroptosis is a targetable detrimental factor in metabolic dysfunction-associated steatotic liver disease

There is an unmet clinical need for pharmacologic treatment for metabolic dysfunction-associated steatotic liver disease (MASLD). Hepatocyte cell death is a hallmark of this highly prevalent chronic liver disease, but the dominant type of cell death remains uncertain. Here we report that ferroptosis, an iron-catalyzed mode of regulated cell death, contributes to MASLD. Unsupervised clustering in a cohort of biopsy-proven MASLD patients revealed a subgroup with hepatic ferroptosis signature and lower glutathione peroxidase 4 (GPX4) levels. Likewise, a subgroup with reduced ferroptosis defenses was discerned in public transcriptomics datasets. Four weeks of choline-deficient L-amino acid-defined high-fat diet (CDAHFD) induced MASLD with ferroptosis in mice. Gpx4 overexpression did not affect steatohepatitis, instead CDAHFD protected from morbidity due to hepatocyte-specific Gpx4 knockout. The ferroptosis inhibitor UAMC-3203 attenuated steatosis and alanine aminotransferase in CDAHFD and a second model, i.e., the high-fat high-fructose diet (HFHFD). The effect of monounsaturated and saturated fatty acids supplementation on ferroptosis susceptibility was assessed in human HepG2 cells. Fat-laden HepG2 showed a drop in ferroptosis defenses, increased phosphatidylglycerol with two polyunsaturated fatty acid (PUFA) lipid tails, and sustained ferroptosis sensitivity. In conclusion, this study identified hepatic ferroptosis as a detrimental factor in MASLD patients. Unexpectedly, non-PUFA supplementation to hepatocytes altered lipid bilayer composition to maintain ferroptosis sensitivity. Based on findings in in vivo models, ferroptosis inhibition represents a promising therapeutic target in MASLD.

Causal relationship between serum metabolites and idiopathic pulmonary fibrosis: Insights from a two-sample Mendelian randomization study

Background

Idiopathic pulmonary fibrosis (IPF) is an irreversible lung disease with unclear pathological mechanisms. In this study, we utilized bidirectional Mendelian randomization (MR) to analyze the relationship between serum metabolites and IPF, and conducted metabolic pathway analysis.

Aim

To determine the causal relationship between serum metabolites and IPF using MR analysis.

Methods

A two-sample MR analysis was conducted to evaluate the causal relationship between 824 serum metabolites and IPF. The inverse variance weighted (IVW) method was used to estimate the causal relationship between exposure and results. Sensitivity analysis was conducted using MR Egger, weighted median, and maximum likelihood to eliminate pleiotropy. Additionally, metabolic pathway analysis was conducted to identify potential metabolic pathways.

Results

We identified 12 serum metabolites (6 risks and 6 protective) associated with IPF from 824 metabolites. Among them, 11 were known and 1 was unknown. 1-Eicosatrienoylglycophorophospholine and 1-myristoylglycophorophospholine were bidirectional MR positive factors, with 1-myristoylglycophorophospholine being a risk factor (1.0013, 1.0097) and 1-eicosatrienoylglycophorine being a protective factor (0.9914, 0.9990). The four lipids (1-linoleoylglycerophoethanolamine*, total cholesterol in large high-density lipoprotein [HDL], cholesterol esters in very large HDL, and phospholipids in very large HDL) and one NA metabolite (degree of unsaturation) were included in the known hazardous metabolites. The known protective metabolites included three types of lipids (carnitine, 1-linoleoylglycerophoethanolamine*, and 1-eicosatrienoylglycerophophophorine), one amino acid (hypoxanthine), and two unknown metabolites (the ratio of omega-6 fatty acids to omega-3 fatty acids, and the ratio of photoshopids to total lipids ratio in chylomicrons and extremely large very low-density lipoprotein [VLDL]). Moreover, sn-Glycerol 3-phosphate and 1-Acyl-sn-glycero-3-phosphocline were found to be involved in the pathogenesis of IPF through metabolic pathways such as Glycerolide metabolism and Glycerophospholipid metabolism.

Conclusion

Our study identified 6 causal risks and 6 protective serum metabolites associated with IPF. Additionally, 2 metabolites were found to be involved in the pathogenesis of IPF through metabolic pathways, providing a new perspective for further understanding the metabolic pathway and the pathogenesis of IPF.

Organelle-Targeted Laurdans Measure Heterogeneity in Subcellular Membranes and Their Responses to Saturated Lipid Stress

Organelles feature characteristic lipid compositions that lead to differences in membrane properties. In cells, membrane ordering and fluidity are commonly measured using the solvatochromic dye Laurdan, whose fluorescence is sensitive to lipid packing. As a general lipophilic dye, Laurdan stains all hydrophobic environments in cells; therefore, it is challenging to characterize membrane properties in specific organelles or assess their responses to pharmacological treatments in intact cells. Here, we describe the synthesis and application of Laurdan-derived probes that read out the membrane packing of individual cellular organelles. The set of organelle-targeted Laurdans (OTL) localizes to the ER, mitochondria, lysosomes, and Golgi compartments with high specificity while retaining the spectral resolution needed to detect biological changes in membrane ordering. We show that ratiometric imaging with OTLs can resolve membrane heterogeneity within organelles as well as changes in lipid packing resulting from inhibition of trafficking or bioenergetic processes. We apply these probes to characterize organelle-specific responses to saturated lipid stress. While the ER and lysosomal membrane fluidity is sensitive to exogenous saturated fatty acids, that of mitochondrial membranes is protected. We then use differences in ER membrane fluidity to sort populations of cells based on their fatty acid diet, highlighting the ability of organelle-localized solvatochromic probes to distinguish between cells based on their metabolic state. These results expand the repertoire of targeted membrane probes and demonstrate their application in interrogating lipid dysregulation.

Rapid and Precise Diagnosis of Retroperitoneal Liposarcoma with Deep-Learned Label-Free Molecular Microscopy

The retroperitoneal liposarcoma (RLPS) is a rare malignancy whose only curative therapy is surgical resection. However, well-differentiated liposarcomas (WDLPSs), one of its most common types, can hardly be distinguished from normal fat during operation without an effective margin assessment method, jeopardizing the prognosis severely with a high recurrence risk. Here, we combined dual label-free nonlinear optical modalities, stimulated Raman scattering (SRS) microscopy and second harmonic generation (SHG) microscopy, to image two predominant tissue biomolecules, lipids and collagen fibers, in 35 RLPSs and 34 normal fat samples collected from 35 patients. The produced dual-modal tissue images were used for RLPS diagnosis based on deep learning. Dramatically decreasing lipids and increasing collagen fibers during tumor progression were reflected. A ResNeXt101-based model achieved 94.7% overall accuracy and 0.987 mean area under the ROC curve (AUC) in differentiating among normal fat, WDLPSs, and dedifferentiated liposarcomas (DDLPSs). In particular, WDLPSs were detected with 94.1% precision and 84.6% sensitivity superior to existing methods. The ablation experiment showed that such performance was attributed to both SRS and SHG microscopies, which increased the sensitivity of recognizing WDLPS by 16.0 and 3.6%, respectively. Furthermore, we utilized this model on RLPS margins to identify the tumor infiltration. Our method holds great potential for accurate intraoperative liposarcoma detection.

Organelle-targeted Laurdans measure heterogeneity in subcellular membranes and their responses to saturated lipid stress

Cell organelles feature characteristic lipid compositions that lead to differences in membrane properties. In living cells, membrane ordering and fluidity are commonly measured using the solvatochromic dye Laurdan, whose fluorescence is sensitive to membrane packing. As a general lipophilic dye, Laurdan stains all hydrophobic environments in cells, so it is challenging to characterize membrane properties in specific organelles or assess their responses to pharmacological treatments in intact cells. Here, we describe the synthesis and application of Laurdan-derived probes that read out membrane packing of individual cellular organelles. The set of Organelle-targeted Laurdans (OTL) localizes to the ER, mitochondria, lysosomes and Golgi compartments with high specificity, while retaining the spectral resolution needed to detect biological changes in membrane packing. We show that ratiometric imaging with OTL can resolve membrane heterogeneity within organelles, as well as changes in membrane packing resulting from inhibition of lipid trafficking or bioenergetic processes. We apply these probes to characterize organelle-specific responses to saturated lipid stress. While ER and lysosomal membrane fluidity is sensitive to exogenous saturated fatty acids, that of mitochondrial membranes is protected. We then use differences in ER membrane fluidity to sort populations of cells based on their fatty acid diet, highlighting the ability of organelle-localized solvatochromic probes to distinguish between cells based on their metabolic state. These results expand the repertoire of targeted membrane probes and demonstrate their application to interrogating lipid dysregulation.

Stimulated Raman Scattering Microscopy Reveals Aberrant Triglyceride Accumulation in Lymphatic Metastasis of Papillary Thyroid Carcinoma

Lipid metabolic alterations are known to play a crucial role in cancer metastasis. As a key hub in lipid metabolism, intracellular neutral lipid accumulation in lipid droplets (LDs) has become a signature of aggressive human cancers. Nevertheless, it remains unclear whether lipid accumulation displays distinctive features in metastatic lesions compared to the primary ones. Here, we integrated multicolor stimulated Raman scattering (SRS) imaging with confocal Raman spectroscopy on the same platform to quantitatively analyze the amount and composition of LDs in intact human thyroid tissues in situ without any processing or labeling. Inspiringly, we found aberrant accumulation of triglycerides (TGs) in lymphatic metastases but not in normal thyroid, primary papillary thyroid carcinoma (PTC), or normal lymph node. In addition, the unsaturation degree of unsaturated TGs was significantly higher in the lymphatic metastases from patients diagnosed with late-stage (T3/T4) PTC compared to those of patients diagnosed with early-stage (T1/T2) PTC. Furthermore, both public sequencing data analysis and our RNA-seq transcriptomic experiment showed significantly higher expression of alcohol dehydrogenase-1B (ADH1B), which is critical to lipid uptake and transport, in lymphatic metastases relative to the primary ones. In summary, these findings unravel the lipid accumulation as a novel marker and therapeutic target for PTC lymphatic metastasis that has a poor response to the regular radioactive iodine therapy.

An Empirical Approach to Derive Water T1 from Multiparametric MR Images Using an Automated Pipeline and Comparison With Liver Stiffness

BACKGROUND

Water T1 of the liver has been shown to be promising in discriminating the progressive forms of fatty liver diseases, inflammation, and fibrosis, yet proper correction for iron and lipid is required.

PURPOSE

To examine the feasibility of an empirical approach for iron and lipid correction when measuring imaging-based T1 and to validate this approach by spectroscopy on in vivo data.

STUDY TYPE

Retrospective.

POPULATION

Next to mixed lipid-iron phantoms, individuals with different hepatic lipid content were investigated, including people with type 1 diabetes (N = 15, %female = 15.6, age = 43.5 ± 14.0), or type 2 diabetes mellitus (N = 21, %female = 28.9, age = 59.8 ± 9.7) and healthy volunteers (N = 9, %female = 11.1, age = 58.0 ± 8.1).

FIELD STRENGTH/SEQUENCES

3 T, balanced steady-state free precession MOdified Look-Locker Inversion recovery (MOLLI), multi- and dual-echo gradient echo Dixon, gradient echo magnetic resonance elastography (MRE).

ASSESSMENT

T1 values were measured in phantoms to determine the respective correction factors. The correction was tested in vivo and validated by proton magnetic resonance spectroscopy (1 H-MRS). The quantification of liver T1 based on automatic segmentation was compared to the T1 values based on manual segmentation. The association of T1 with MRE-derived liver stiffness was evaluated.

STATISTICAL TESTS

Bland-Altman plots and intraclass correlation coefficients (ICCs) were used for MOLLI vs. 1 H-MRS agreement and to compare liver T1 values from automatic vs. manual segmentation. Pearson's r correlation coefficients for T1 with hepatic lipids and liver stiffness were determined. A P-value of 0.05 was considered statistically significant.

RESULTS

MOLLI T1 values after correction were found in better agreement with the 1 H-MRS-derived water T1 (ICC = 0.60 [0.37; 0.76]) in comparison with the uncorrected T1 values (ICC = 0.18 [-0.09; 0.44]). Automatic quantification yielded similar liver T1 values (ICC = 0.9995 [0.9991; 0.9997]) as with manual segmentation. A significant correlation of T1 with liver stiffness (r = 0.43 [0.11; 0.67]) was found. A marked and significant reduction in the correlation strength of T1 with liver stiffness (r = 0.05 [-0.28; 0.38], P = 0.77) was found after correction for hepatic lipid content.

DATA CONCLUSION

Imaging-based correction factors enable accurate estimation of water T1 in vivo.

LEVEL OF EVIDENCE

1 TECHNICAL EFFICACY: Stage 1.

Emerging role of ferroptosis in metabolic dysfunction-associated steatotic liver disease: revisiting hepatic lipid peroxidation

Metabolic dysfunction-associated steatohepatitis (MASH) is characterised by cell death of parenchymal liver cells which interact with their microenvironment to drive disease activity and liver fibrosis. The identification of the major death type could pave the way towards pharmacotherapy for MASH. To date, increasing evidence suggest a type of regulated cell death, named ferroptosis, which occurs through iron-catalysed peroxidation of polyunsaturated fatty acids (PUFA) in membrane phospholipids. Lipid peroxidation enjoys renewed interest in the light of ferroptosis, as druggable target in MASH. This review recapitulates the molecular mechanisms of ferroptosis in liver physiology, evidence for ferroptosis in human MASH and critically appraises the results of ferroptosis targeting in preclinical MASH models. Rewiring of redox, iron and PUFA metabolism in MASH creates a proferroptotic environment involved in MASH-related hepatocellular carcinoma (HCC) development. Ferroptosis induction might be a promising novel approach to eradicate HCC, while its inhibition might ameliorate MASH disease progression.

Machine Learning Enabled Photoacoustic Spectroscopy for Noninvasive Assessment of Breast Tumor Progression In Vivo: A Preclinical Study

Breast cancer is a dreaded disease affecting women the most in cancer-related deaths over other cancers. However, early diagnosis of the disease can help increase survival rates. The existing breast cancer diagnosis tools do not support the early diagnosis of the disease. Therefore, there is a great need to develop early diagnostic tools for this cancer. Photoacoustic spectroscopy (PAS), being very sensitive to biochemical changes, can be relied upon for its application in detecting breast tumors in vivo. With this motivation, in the current study, an aseptic chamber integrated photoacoustic (PA) probe was designed and developed to monitor breast tumor progression in vivo, established in nude mice. The device served the dual purpose of transporting tumor-bearing animals to the laboratory from the animal house and performing PA experiments in the same chamber, maintaining sterility. In the current study, breast tumor was induced in the nude mice by MCF-7 cells injection and the corresponding PA spectra at different time points (day 0, 5, 10, 15, and 20) of tumor progression in vivo in the same animals. The recorded photoacoustic spectra were subsequently preprocessed, wavelet-transformed, and subjected to filter-based feature selection algorithm. The selected top 20 features, by minimum redundancy maximum relevance (mRMR) algorithm, were then used to build an input feature matrix for machine learning (ML)-based classification of the data. The performance of classification models demonstrated 100% specificity, whereas the sensitivity of 95, 100, 92.5, and 85% for the time points, day 5, 10, 15, and 20, respectively. These results suggest the potential of PA signal-based classification of breast tumor progression in a preclinical model. The PA signal contains information on the biochemical changes associated with disease progression, emphasizing its translational strength toward early disease diagnosis.

Discrimination of lipid composition and cellular localization in human liver tissues by stimulated Raman scattering microscopy

Significance

The molecular mechanisms driving the progression from nonalcoholic fatty liver (NAFL) to fibrosing steatohepatitis (NASH) are insufficiently understood. Techniques enabling the characterization of different lipid species with both chemical and spatial information can provide valuable insights into their contributions to the disease progression.

Aim

We extend the utility of stimulated Raman scattering (SRS) microscopy to characterize and quantify lipid species in liver tissue sections from patients with NAFL and NASH.

Approach

We applied a dual-band hyperspectral SRS microscopy system for imaging tissue sections in both the C-H stretching and fingerprint regions. The same sections were imaged with polarization microscopy for detecting birefringent liquid crystals in the tissues.

Results

Our imaging and analysis pipeline provides accurate classification and quantification of free cholesterol, saturated cholesteryl esters (CEs), unsaturated CE, and triglycerides in liver tissue sections. The subcellular resolution enables investigations of the heterogeneous distribution of saturated CE, which has been under-examined in previous studies. We also discovered that the birefringent crystals, previously found to be associated with NASH development, are predominantly composed of saturated CE.

Conclusions

Our method allows for a detailed characterization of lipid composition in human liver tissues and enables further investigation into the potential mechanism of NASH progression.

Targeting metabolic reprogramming in hepatocellular carcinoma to overcome therapeutic resistance: A comprehensive review

Hepatocellular carcinoma (HCC) poses a heavy burden on human health with high morbidity and mortality rates. Systematic therapy is crucial for advanced and mid-term HCC, but faces a significant challenge from therapeutic resistance, weakening drug effectiveness. Metabolic reprogramming has gained attention as a key contributor to therapeutic resistance. Cells change their metabolism to meet energy demands, adapt to growth needs, or resist environmental pressures. Understanding key enzyme expression patterns and metabolic pathway interactions is vital to comprehend HCC occurrence, development, and treatment resistance. Exploring metabolic enzyme reprogramming and pathways is essential to identify breakthrough points for HCC treatment. Targeting metabolic enzymes with inhibitors is key to addressing these points. Inhibitors, combined with systemic therapeutic drugs, can alleviate resistance, prolong overall survival for advanced HCC, and offer mid-term HCC patients a chance for radical resection. Advances in metabolic research methods, from genomics to metabolomics and cells to organoids, help build the HCC metabolic reprogramming network. Recent progress in biomaterials and nanotechnology impacts drug targeting and effectiveness, providing new solutions for systemic therapeutic drug resistance. This review focuses on metabolic enzyme changes, pathway interactions, enzyme inhibitors, research methods, and drug delivery targeting metabolic reprogramming, offering valuable references for metabolic approaches to HCC treatment.

Coherent Raman scattering microscopy of lipid droplets in cells and tissues

Lipid droplets (LDs) play a key role as the hub for lipid metabolism to maintain cellular metabolic homeostasis. Understanding the functions and changes of LDs in different pathological conditions is crucial for identifying new markers for diagnosis and discovering new targets for treatment. In recent years, coherent Raman scattering (CRS) microscopy has been popularized for the imaging and quantification of LDs in live cells. Compared to spontaneous Raman scattering microscopy, CRS microscopy offers a much higher imaging speed while maintaining similar chemical information. Due to the high lipid density, LDs usually have strong CRS signals and therefore are the most widely studied organelle in the CRS field. In this review, we discuss recent achievements using CRS to study the quantity, distribution, composition, and dynamics of LDs in various systems.

Relevance of multilamellar and multicompartmental vesicles in biological fluids: understanding the significance of proportional variations and disease correlation

Extracellular vesicles (EVs) have garnered significant interest in the field of biomedical science due to their potential applications in therapy and diagnosis. These vesicles participate in cell-to-cell communication and carry a diverse range of bioactive cargo molecules, such as nucleic acids, proteins, and lipids. These cargoes play essential roles in various signaling pathways, including paracrine and endocrine signaling. However, our understanding of the morphological and structural features of EVs is still limited. EVs could be unilamellar or multilamellar or even multicompartmental structures. The relative proportions of these EV subtypes in biological fluids have been associated with various human diseases; however, the mechanism remains unclear. Cryo-electron microscopy (cryo-EM) holds great promise in the field of EV characterization due to high resolution properties. Cryo-EM circumvents artifacts caused by fixation or dehydration, allows for the preservation of native conformation, and eliminates the necessity for staining procedures. In this review, we summarize the role of EVs biogenesis and pathways that might have role on their structure, and the role of cryo-EM in characterization of EVs morphology in different biological samples and integrate new knowledge of the alterations of membranous structures of EVs which could be used as biomarkers to human diseases.

Raman Imaging Reveals Insights into Membrane Phase Biophysics in Cells

Cellular membranes are essential components of all living organisms. They are composed of a complex mixture of lipids with diverse chemical structures and crucial biological functions. The dynamic and heterogeneous nature of cellular membranes presents a challenge for studying their biophysical properties and organization in vivo. Raman imaging, particularly coherent Raman scattering techniques such as stimulated Raman scattering (SRS) microscopy, have emerged as powerful tools for studying cellular membranes with high spatial and temporal resolution and minimal perturbation. In this Review, we discuss the scientific importance and technical challenges of characterizing membrane composition in cellular contexts and how the advances of Raman imaging can provide unique insights into membrane phase behavior and organization. We also highlight recent applications of Raman imaging in studying cellular membranes and implications in diseases. In particular, the discovery of phase separation and a solid-phase intracellular membrane on endoplasmic reticulum is reviewed in detail, shedding light on the biology of lipotoxicity.