Elevated intracellular copper contributes a unique role to kidney fibrosis by lysyl oxidase mediated matrix crosslinking

Mammalian copper homeostasis: physiological roles and molecular mechanisms

In the past decade, evidence for the numerous roles of copper (Cu) in mammalian physiology has grown exponentially. The discoveries of Cu involvement in cell signaling, autophagy, cell motility, differentiation, and regulated cell death (cuproptosis) have markedly extended the list of already known functions of Cu, such as a cofactor of essential metabolic enzymes, a protein structural component, and a regulator of protein trafficking. Novel and unexpected functions of Cu transporting proteins and enzymes have been identified, and new disorders of Cu homeostasis have been described. Significant progress has been made in the mechanistic studies of two classic disorders of Cu metabolism, Menkes disease and Wilson's disease, which paved the way for novel approaches to their treatment. The discovery of cuproptosis and the role of Cu in cell metastatic growth have markedly increased interest in targeting Cu homeostatic pathways to treat cancer. In this review, we summarize the established concepts in the field of mammalian Cu physiology and discuss how new discoveries of the past decade expand and modify these concepts. The roles of Cu in brain metabolism and in cell functional speciation and a recently discovered regulated cell death have attracted significant attention and are highlighted in this review.

Elevated serum and urinary secreted protein acidic and rich in cysteine levels are novel biomarkers of kidney fibrosis severity

BACKGROUND

Interstitial fibrosis is the primary determinant of the progression of chronic kidney disease (CKD), and noninvasive identification of interstitial fibrosis is a major challenge. We aimed to explore the diagnostic value of secreted protein acidic and rich in cysteine (SPARC) in serum and urine in kidney fibrosis.

METHODS

Single-cell transcriptome analysis was used to measure SPARC expression in healthy reference kidneys and those of patients with CKD. A total of 674 patients with CKD who underwent renal biopsy served as the training cohort (n = 322) and the validation cohort (n = 352). Serum and urinary SPARC levels were measured at the time of kidney biopsy. In vivo and in vitro models of kidney fibrosis were also used to confirm the role of SPARC.

RESULTS

Increased SPARC expression was detected in kidney fibrosis tissues. Higher serum SPARC levels were associated with increased severity of kidney fibrosis. Moreover, the area under the receiver operating characteristic curve (AUC-ROC) (AUC 0.86) was greater for the serum SPARC level than for the urinary SPARC level and estimated glomerular filtration rate (eGFR). The combination of the serum and urinary SPARC levels and eGFR increased the AUC-ROC for predicting kidney fibrosis from 0.86 to 0.90. The diagnostic performance of serum or urinary SPARC levels was consistent in the validation cohort. In vivo and in vitro models of kidney fibrosis also confirmed the upregulation of SPARC expression.

CONCLUSIONS

Serum and urinary SPARC levels may be potential biomarkers for kidney fibrosis and may be useful for noninvasive diagnosis.

Emerging perspectives of copper-mediated transcriptional regulation in mammalian cell development

Copper (Cu) is a vital micronutrient necessary for proper development and function of mammalian cells and tissues. Cu mediates the function of redox active enzymes that facilitate metabolic processes and signaling pathways. Cu levels are tightly regulated by a network of Cu-binding transporters, chaperones, and small molecule ligands. Extensive research has focused on the mammalian Cu homeostasis (cuprostasis) network and pathologies, which result from mutations and perturbations. There are roles for Cu-binding proteins as transcription factors (Cu-TFs) and regulators that mediate metal homeostasis through the activation or repression of genes associated with Cu handling. Emerging evidence suggests that Cu and some Cu-TFs may be involved in the regulation of targets related to development-expanding the biological roles of Cu-binding proteins. Cu and Cu-TFs are implicated in embryonic and tissue-specific development alongside the mediation of the cellular response to oxidative stress and hypoxia. Cu-TFs are also involved in the regulation of targets implicated in neurological disorders, providing new biomarkers and therapeutic targets for diseases such as Parkinson's disease, prion disease, and Friedreich's ataxia. This review provides a critical analysis of the current understanding of the role of Cu and cuproproteins in transcriptional regulation.

Focus on cuproptosis: Exploring new mechanisms and therapeutic application prospects of cuproptosis regulation

Cuproptosis is a novel form of regulated cell death, which plays an important role in the physiological and pathological processes of the human body. Despite the increasing research on cuproptosis-related genes (CRGs) and their correlation with diseases, the pathogenesis of cuproptosis-related diseases remains unclear. Furthermore, there is a lack of reviews on the emerging technologies for regulating cuproptosis in disease treatment. This study delves into the copper-induced cell death mechanism, distinguishing cuproptosis from mechanisms like oxidative stress, glutathione synthesis inhibition, and ubiquitin-proteasome system inhibition. Several long-standing mysteries of diseases such as Wilson's disease and Menkes disease may be attributed to the occurrence of cuproptosis. In addition, we also review the detection indicators related to cuproptosis, providing targets for the diagnosis of cuproptosis-related diseases, and summarize the application value of cuproptosis in tumor therapy to better elucidate the impact of copper in cell death and diseases, and thus to promote the application prospects and possible strategies of cuproptosis-related substances, such as copper ion chelators, copper ion carriers, and copper nanomaterials, in disease therapy.

Mitochondrial copper overload promotes renal fibrosis via inhibiting pyruvate dehydrogenase activity

Copper is a trace element essential for numerous biological activities, whereas the mitochondria serve as both major sites of intracellular copper utilization and copper reservoir. Here, we investigated the impact of mitochondrial copper overload on the tricarboxylic acid cycle, renal senescence and fibrosis. We found that copper ion levels are significantly elevated in the mitochondria in fibrotic kidney tissues, which are accompanied by reduced pyruvate dehydrogenase (PDH) activity, mitochondrial dysfunction, cellular senescence and renal fibrosis. Conversely, lowering mitochondrial copper levels effectively restore PDH enzyme activity, improve mitochondrial function, mitigate cellular senescence and renal fibrosis. Mechanically, we found that mitochondrial copper could bind directly to lipoylated dihydrolipoamide acetyltransferase (DLAT), the E2 component of the PDH complex, thereby changing the interaction between the subunits of lipoylated DLAT, inducing lipoylated DLAT protein dimerization, and ultimately inhibiting PDH enzyme activity. Collectively, our study indicates that mitochondrial copper overload could inhibit PDH activity, subsequently leading to mitochondrial dysfunction, cellular senescence and renal fibrosis. Reducing mitochondrial copper overload might therefore serve as a strategy to rescue renal fibrosis.

An AIE Controlled "Off-On" Cu2+-Sensitive Probe for Early Detection of Renal Fibrosis

Early detection of renal fibrosis (RF) is very important given that it is irreversible when it progresses to the terminal stage. A key marker of RF pathogenesis is activation of myomyofibroblasts, and its targeted imaging may be a promising approach for early detection of RF, but no study has directly imaged activation of renal myomyofibroblasts. Cu2+ plays a major role in the fibrotic activity of myofibroblasts. Herein, inspired by that Cu2+ can complex with bovine serum albumin (BSA), BSA-Ag2S quantum dots (QDs) with aggregation-induced emission (AIE) property are synthesized. Then BSA-Ag2S QDs are modified by chitosan (CS) with renal targeting and hyaluronic acid (HA) with myofibroblast targeting to obtain the AIE assay system (QDs@CS@HA). The system is simple to synthesize, and produces a rapid NIR fluorescence signal turn-on response and a low detection limit of 75 × 10-9 m to Cu2+. In addition, cellular and animal experiments have shown that QDs@CS@HA has good biosafety and cell-targeted imaging capability for RF. Based on the successful application of QDs@CS@HA and the mechanism of RF progression in early RF detection, it is expected that QDs@CS@HA may detect RF before the appearance of clinical symptoms.

Plasma levels and dietary intake of minerals in patients with type 2 diabetes and chronic kidney disease: A case-control study

BACKGROUND AND AIM

Diabetic kidney disease (DKD) is the primary cause of chronic kidney disease (CKD) worldwide. Altered mineral levels leading to adverse outcomes are widely reported in diabetes but limited in DKD, in the Indian scenario, hence this study was taken up to address this issue.

METHODS

A hospital-based case-control study was taken up with 54 healthy controls (C) and 140 subjects with type 2 diabetes wherein 74 subjects with diabetes and CKD formed the DKD group, and 66 subjects with diabetes but no CKD formed the diabetic no-chronic kidney disease (DNCKD) group. High-resolution inductively coupled plasma mass spectrometry was used to evaluate the blood levels of minerals (calcium (Ca), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), copper (Cu), zinc (Zn), and selenium (Se)), and a raw food-based food frequency questionnaire for dietary intakes. Estimated glomerular filtration rate (eGFR) was calculated using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation (mL/min/1.73 m2) and albuminuria. Spearman's rank correlation was used to evaluate the relationship between the categorical variables.

RESULTS

The median values of plasma Ca in the DKD group were significantly lower compared with the DNCKD and C groups (10.5 mg/dL vs. 11.0 mg/dL and 11.7 mg/dL, p<0.001). Furthermore, plasma Ca levels lowered with declining kidney function, as evidenced by the eGFR and albuminuria segregation. Dietary intake of minerals did not correlate with the corresponding plasma levels. However, in the DKD group, eGFR correlated positively with the plasma levels of Ca (r= 0.422, p=0.001), Cr (r= 0.351, p=0.008), Mn (r= 0.338, p=0.011), Fe (r= 0.403, p=0.002), Cu (r= 0.274, p=0.041) and negatively with Se (r= -0.486, p<0.001).

CONCLUSION

Plasma Ca levels are lower in the DKD group with a strong positive association with eGFR, indicating its role in predicting the onset and progression of kidney function decline.

Copper homeostasis dysregulation in respiratory diseases: a review of current knowledge

Cu is an essential micronutrient for various physiological processes in almost all human cell types. Given the critical role of Cu in a wide range of cellular processes, the local concentrations of Cu and the cellular distribution of Cu transporter proteins in the lung are essential for maintaining a steady-state internal environment. Dysfunctional Cu metabolism or regulatory pathways can lead to an imbalance in Cu homeostasis in the lungs, affecting both acute and chronic pathological processes. Recent studies have identified a new form of Cu-dependent cell death called cuproptosis, which has generated renewed interest in the role of Cu homeostasis in diseases. Cuproptosis differs from other known cell death pathways. This occurs through the direct binding of Cu ions to lipoylated components of the tricarboxylic acid cycle during mitochondrial respiration, leading to the aggregation of lipoylated proteins and the subsequent downregulation of Fe-S cluster proteins, which causes toxic stress to the proteins and ultimately leads to cell death. Here, we discuss the impact of dysregulated Cu homeostasis on the pathogenesis of various respiratory diseases, including asthma, chronic obstructive pulmonary disease, idiopathic interstitial fibrosis, and lung cancer. We also discuss the therapeutic potential of targeting Cu. This study highlights the intricate interplay between copper, cellular processes, and respiratory health. Copper, while essential, must be carefully regulated to maintain the delicate balance between necessity and toxicity in living organisms. This review highlights the need to further investigate the precise mechanisms of copper interactions with infections and immune inflammation in the context of respiratory diseases and explore the potential of therapeutic strategies for copper, cuproptosis, and other related effects.

Role of Nutrients in Pediatric Non-Dialysis Chronic Kidney Disease: From Pathogenesis to Correct Supplementation

Nutrition management is fundamental for children with chronic kidney disease (CKD). Fluid balance and low-protein and low-sodium diets are the more stressed fields from a nutritional point of view. At the same time, the role of micronutrients is often underestimated. Starting from the causes that could lead to potential micronutrient deficiencies in these patients, this review considers all micronutrients that could be administered in CKD to improve the prognosis of this disease.

Bioinformatics-based dynamics of cuproptosis -related indicators in experimental silicosis

Pneumoconiosis is one of the most serious occupational diseases worldwide. Silicosis due to prolonged inhalation of free silica dust during occupational activities is one of the main types. Cuproptosis is a newly discovered mode of programmed cell death characterized by the accumulation of free copper in the cell, which ultimately leads to cell death. Increased copper in the serum of silicosis patients, suggests that the development of silicosis is accompanied by changes in copper metabolism, but whether cuproptosis is involved in the progression of silicosis is actually to be determined. To test this hypothesis, we screened the genetic changes in patients with idiopathic fibrosis by bioinformatics methods and predicted and functionally annotated the cuproptosis-related genes among them. Subsequently, we established a mouse silicosis model and detected the concentration of copper ions and the activity of ceruloplasmin (CP) in serum, as well as changes of the concentration of copper and cuproptosis related genes in mouse lung tissues. We identified 9 cuproptosis-related genes among the differential genes in patients with IPF at different times and the tissue-specific expression levels of ferredoxin 1 (FDX1) and Lipoyl synthase (LIAS) proteins. Furthermore, serum CP activity and copper ion levels in silicosis mice were elevated on days 7th and 56th after silica exposure. The expression of CP in mouse lung tissue elevated at all stages after silica exposure. The mRNA level of FDX1 decreased on days 7th and 56th, and the protein level remained in accordance with the mRNA level on day 56th. LIAS and Dihydrolipoamide dehydrogenase (DLD) levels were downregulated at all times after silica exposure. In addition, Heatshockprotein70 (HSP70) expression was increased on day 56. In brief, our results demonstrate that there may be cellular cuproptosis during the development of experimental silicosis in mice and show synchronization with enhanced copper loading in mice.

The role of epithelial cells in fibrosis: Mechanisms and treatment

Fibrosis is a pathological process that affects multiple organs and is considered one of the major causes of morbidity and mortality in multiple diseases, resulting in an enormous disease burden. Current studies have focused on fibroblasts and myofibroblasts, which directly lead to imbalance in generation and degradation of extracellular matrix (ECM). In recent years, an increasing number of studies have focused on the role of epithelial cells in fibrosis. In some cases, epithelial cells are first exposed to external physicochemical stimuli that may directly drive collagen accumulation in the mesenchyme. In other cases, the source of stimulation is mainly immune cells and some cytokines, and epithelial cells are similarly altered in the process. In this review, we will focus on the multiple dynamic alterations involved in epithelial cells after injury and during fibrogenesis, discuss the association among them, and summarize some therapies targeting changed epithelial cells. Especially, epithelial mesenchymal transition (EMT) is the key central step, which is closely linked to other biological behaviors. Meanwhile, we think studies on disruption of epithelial barrier, epithelial cell death and altered basal stem cell populations and stemness in fibrosis are not appreciated. We believe that therapies targeted epithelial cells can prevent the progress of fibrosis, but not reverse it. The epithelial cell targeting therapies will provide a wonderful preventive and delaying action.

Copper chelation reduces early collagen deposition and preserves saliva secretion in irradiated salivary glands

Radiation therapy is a first-line treatment for head and neck cancer; however, it typically leads to hyposalivation stemming from fibrosis of the salivary gland. Current strategies to restore glandular function are dependent on the presence of residual functional salivary gland tissue, a condition commonly not met in patients with extensive fibrotic coverage of the salivary gland resulting from radiation therapy. Fibrosis is defined by the pathological accumulation of connective tissue (i.e., extracellular matrix) and excessive deposition of crosslinked (fibrillar) collagen that can impact a range of tissues and given that collagen crosslinking is necessary for fibrosis formation, inhibiting this process is a reasonable focus for developing anti-fibrotic therapies. Collagen crosslinking is catalyzed by the lysyl oxidase family of secreted copper-dependent metalloenzymes, and since that copper is an essential cofactor in all lysyl oxidase family members, we tested whether localized delivery of a copper chelator into the submandibular gland of irradiated mice could suppress collagen deposition and preserve the structure and function of this organ. Our results demonstrate that transdermal injection of tetrathiomolybdate into salivary glands significantly reduced the early deposition of fibrillar collagen in irradiated mice and preserved the integrity and function of submandibular gland epithelial tissue. Together, these studies identify copper metabolism as a novel therapeutic target to control radiation induced damage to the salivary gland and the current findings further indicate the therapeutic potential of repurposing clinically approved copper chelators as neoadjuvant treatments for radiation therapy.

The Cross-Communication of Cuproptosis and Regulated Cell Death in Human Pathophysiology

Copper (Cu) plays a crucial and diverse function in biological systems, acting as a cofactor at numerous sites of enzymatic activity and participating in various physiological processes, including oxidative stress regulation, lipid metabolism, and energy metabolism. Similar to other micronutrients, the body regulates Cu levels to ensure homeostasis; any disruption in Cu homeostasis may result in various illnesses. Cuproptosis causes proteotoxic stress and ultimately results in cell death by the binding of Cu ions to lipid-acylated proteins during the tricarboxylic acid cycle of mitochondrial respiration. Cu is not only involved in regulatory cell death (RCD), but also in exogenous factors that induce cellular responses and toxic outcomes. Cu imbalances also affect the transmission of several RCD messages. Therefore, this article presents a thorough examination of the mechanisms involved in Cu-induced RCD as well as the role of Cu complexes in its pathophysiology.

Copper homeostasis and cuproptosis in mitochondria

Mitochondria serve as sites for energy production and are essential for regulating various forms of cell death induced by metal metabolism, targeted anticancer drugs, radiotherapy and immunotherapy. Cuproptosis is an autonomous form of cell death that depends on copper (Cu) and mitochondrial metabolism. Although the recent discovery of cuproptosis highlights the significance of Cu and mitochondria, there is still a lack of biological evidence and experimental verification for the underlying mechanism. We provide an overview of how Cu and cuproptosis affect mitochondrial morphology and function. Through comparison with ferroptosis, similarities and differences in mitochondrial metabolism between cuproptosis and ferroptosis have been identified. These findings provide implications for further exploration of cuproptotic mechanisms. Furthermore, we explore the correlation between cuproptosis and immunotherapy or radiosensitivity. Ultimately, we emphasize the therapeutic potential of targeting cuproptosis as a novel approach for disease treatment.

Single-cell analysis reveals lysyl oxidase (Lox)+ fibroblast subset involved in cardiac fibrosis of diabetic mice

INTRODUCTION

Myocardial fibrosis and cardiac dysfunction are the main characteristics of diabetic heart disease. However, the molecular mechanisms underlying diabetic myocardial fibrosis remain unclear.

OBJECTIVES

This study aimed to investigate the heterogeneity of cardiac fibroblasts in diabetic mice and its possible mechanism in the development of diabetic myocardial fibrosis.

METHODS

We established a diabetic mouse model by injecting mice with streptozotocin. The overall cell profiles in diabetic hearts were analyzed using single-cell RNA transcriptomic techniques. Cardiac function was evaluated by echocardiography. Cardiac fibrosis was assessed by Masson's trichrome and Sirius red staining. Protein expression was analyzed using Western blotting and immunofluorescence staining.

RESULTS

A total of 11,585 cells were captured in control (Ctrl) and diabetic (DM) hearts. Twelve cell types were identified in this study. The number of fibroblasts was significantly higher in the DM hearts than in the Ctrl group. The fibroblasts were further re-clustered into nine subsets. Interestingly, cluster 4 fibroblasts were significantly increased in diabetic hearts compared with other fibroblast clusters. Lysyl oxidase (Lox) was highly expressed in DM fibroblasts (especially in cluster 4). Beta-aminopropionitrile, a Lox inhibitor, inhibited collagen expression and alleviated cardiac dysfunction in the diabetic group. Lysyl oxidase inhibition also reduced high glucose-induced collagen protein upregulation in primary fibroblasts. Moreover, a TGF-β receptor inhibitor not only prevented an increase in Lox and Col I but also inhibited the phosphorylation of Smad2/3 in fibroblasts.

CONCLUSIONS

This study revealed the heterogeneity of cardiac fibroblasts in diabetic mice for the first time. Fibroblasts with high expression of Lox (cluster 4 fibroblasts) were identified to play a crucial role in fibrosis in diabetic heart disease. The findings of this study may provide a possible therapeutic target for interstitial fibrosis.

COX17 restricts renal fibrosis development by maintaining mitochondrial copper homeostasis and restoring complex IV activity

Renal fibrosis relies on multiple proteins and cofactors in its gradual development. Copper is a cofactor of many enzymes involved in renal microenvironment homeostasis. We previously reported that intracellular copper imbalance occurred during renal fibrosis development and was correlated with fibrosis intensity. In this study, we investigated the molecular mechanisms of how copper affected renal fibrosis development. Unilateral ureteral obstruction (UUO) mice were used for in vivo study; rat renal tubular epithelial cells (NRK-52E) treated with TGF-β1 were adapted as an in vitro fibrotic model. We revealed that the accumulation of copper in mitochondria, rather than cytosol, was responsible for mitochondrial dysfunction, cell apoptosis and renal fibrosis in both in vivo and in vitro fibrotic models. Furthermore, we showed that mitochondrial copper overload directly disrupted the activity of respiratory chain complex IV (cytochrome c oxidase), but not complex I, II and III, which hampered respiratory chain and disrupted mitochondrial functions, eventually leading to fibrosis development. Meanwhile, we showed that COX17, the copper chaperone protein, was significantly upregulated in the mitochondria of fibrotic kidneys and NRK-52E cells. Knockdown of COX17 aggravated mitochondrial copper accumulation, inhibited complex IV activity, augmented mitochondrial dysfunction and led to cell apoptosis and renal fibrosis, whereas overexpression of COX17 could discharge copper from mitochondria and protect mitochondrial function, alleviating renal fibrosis. In conclusion, copper accumulation in mitochondria blocks complex IV activity and induces mitochondrial dysfunction. COX17 plays a pivotal role in maintaining mitochondrial copper homeostasis, restoring complex IV activity, and ameliorating renal fibrosis.

FOSL2 participates in renal fibrosis via SGK1-mediated epithelial-mesenchymal transition of proximal tubular epithelial cells

Background

Fos-related antigen 2 (FOSL2) plays a facilitative role in fibrotic disease; however, its role in renal fibrosis remains unclear. This study aimed to clarify the role and underlying mechanisms of FOSL2 in renal fibrosis.

Methods

Upregulated genes in unilateral ureteral obstruction (UUO)-injured kidneys were screened in Gene Expression Omnibus (GEO) databases, and overlapping genes were identified using Venn diagram software. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed for these genes. The UUO-induced mouse model and transforming growth factor-β1 (TGF-β1)-induced cell model were used for the in vivo and in vitro studies.

Results

A total of 43 commonly upregulated genes were identified. GO and KEGG pathway analyses indicated that FOSL2 may be involved in fibrosis. Furthermore, FOSL2 was confirmed to be upregulated in UUO-injured kidneys and TGF-β1-induced cells. Knockdown of FOSL2 ameliorated interstitial fibrosis, extracellular matrix deposition, and epithelial-mesenchymal transition via the downregulation of fibronectin, α-smooth muscle actin (α-SMA), collagen type I (Col1a1 and Col1a2), and Col5a1 and upregulation of E-cadherin. Bioinformatics analysis revealed that serum/glucocorticoid regulated kinase 1 (SGK1) may be regulated by FOSL2 and involved in renal fibrosis. Further experiments confirmed that TGF-β1 enhanced SGK1 expression and transcription, which were reversed by FOSL2 silencing. Moreover, FOSL2 was bound to the SGK1 promoter, and SGK1 overexpression reversed the effects of FOSL2 silencing in TGF-β1-induced cells.

Conclusion

FOSL2 plays an essential role in promoting renal fibrosis in an SGK1-dependent manner, and targeting the FOSL2/SGK1 signaling axis may offer a potential strategy for the treatment of renal fibrosis.

The Antihyperglycemic Effect of Crude Liang (Gnetum gnemon var. tenerum) Leaves Powder on Wistar Rats

Chlorophyll and chlorophyllin (CHL) demonstrated antidiabetic activity by inhibiting gluconeogenesis and increasing glucose uptake in rats' muscle cells. Liang leaves contain high amounts of chlorophyll and chlorophyllin and may provide an antidiabetic effect. The antidiabetic activity of chlorophyll and CHL contained in Liang leaves, Cu-chlorophyllin (CCL) Liang leaves treated with CuSO4, and untreated crude Liang leaves (CLL) were compared using commercial chlorophyllin (CHL) as a reference. Twelve Wistar male rats were separated into 4 groups (3 rats/group); the first was a normal one (based line group), the second were the diabetic rats treated with CHL, while the third and the fourth were the diabetic rats treated with 0.97 g/kg of CCL and CLL, respectively. Diabetic rats were induced by a high fructose diet, before being taken to administer commercial CHL, CCL, and CLL for 7 days. Nonfasting blood glucose and body weight were checked daily. After euthanasia, organ weight, biochemical, hematological, and histopathological properties were evaluated. CCL treatment showed no antihyperglycemic activity in the rat model but caused some biochemical abnormalities and thrombocytopenia. Commercial CHL gave a higher reduction of nonfasting blood glucose (NFBG) than Liang leaves powder CCL or CLL but also showed some signs of abnormal biochemical parameters. CLL exhibited an antihyperglycemic effect, with higher body weight and increased HDL/LDL ratio and thus could be a promising alternative natural source for diabetes treatment.

Lysyl oxidase-responsive anchoring nanoparticles for modulation of the tumor immune microenvironment

In the tumor microenvironment, lysyl oxidase (LOX) is known to play a key role in stabilizing the tumor extracellular matrix. Here, we designed LOX-responsive nanoparticles to interact with the collagen matrix of the tumor microenvironment. Collagen-coated and imiquimod-loaded polydopamine nanoparticles (CPN/IQ) could form crosslinked structures with the collagen matrix via LOX. In vitro, anchoring of CPN/IQ nanoparticles was observed with LOX-secreting CT26 cells, but this was blocked by a LOX inhibitor. In CT26 tumor-bearing mice, co-administration of nanoparticles plus the LOX inhibitor did not significantly alter the antitumor efficacy among nanoparticles. In the absence of the LOX inhibitor, however, a single administration of CPN/IQ could provide sustained responsiveness to near-infrared irradiation and ablation of primary tumors. In the primary tumor microenvironment, CPN/IQ lowered the Treg cell population but increased the cytotoxic CD3+CD8+ T cell population. In splenic dendritic cells, CPN/IQ treatment significantly increased the CD11c+CD86+ and CD11c+CD80+ cell populations. In a CT26 distant tumor-rechallenge model, CPN/IQ treatment increased the cytotoxic CD3+CD8+ T cell population and provided 100% survival of mice until 64 days. This study indicates the feasibility of tumor immune microenvironment modulation using LOX-responsive size-transforming nanoparticles. Although we tested the concept in a CT26 cell-derived tumor model, the concept of LOX-responsive collagen matrix- anchoring nanoparticles may be broadly applied to other tumor tissues with LOX-rich tumor microenvironments.

Toxicity of Heavy Metals and Recent Advances in Their Removal: A Review

Natural and anthropogenic sources of metals in the ecosystem are perpetually increasing; consequently, heavy metal (HM) accumulation has become a major environmental concern. Human exposure to HMs has increased dramatically due to the industrial activities of the 20th century. Mercury, arsenic lead, chrome, and cadmium have been the most prevalent HMs that have caused human toxicity. Poisonings can be acute or chronic following exposure via water, air, or food. The bioaccumulation of these HMs results in a variety of toxic effects on various tissues and organs. Comparing the mechanisms of action reveals that these metals induce toxicity via similar pathways, including the production of reactive oxygen species, the inactivation of enzymes, and oxidative stress. The conventional techniques employed for the elimination of HMs are deemed inadequate when the HM concentration is less than 100 mg/L. In addition, these methods exhibit certain limitations, including the production of secondary pollutants, a high demand for energy and chemicals, and reduced cost-effectiveness. As a result, the employment of microbial bioremediation for the purpose of HM detoxification has emerged as a viable solution, given that microorganisms, including fungi and bacteria, exhibit superior biosorption and bio-accumulation capabilities. This review deals with HM uptake and toxicity mechanisms associated with HMs, and will increase our knowledge on their toxic effects on the body organs, leading to better management of metal poisoning. This review aims to enhance comprehension and offer sources for the judicious selection of microbial remediation technology for the detoxification of HMs. Microbial-based solutions that are sustainable could potentially offer crucial and cost-effective methods for reducing the toxicity of HMs.

Myocardin-related transcription factor contributes to renal fibrosis through the regulation of extracellular microenvironment surrounding fibroblasts

Fibroblast accumulation and extracellular matrix (ECM) deposition are common critical steps for the progression of organ fibrosis, but the precise molecular mechanisms remain to be fully investigated. We have previously demonstrated that lysophosphatidic acid contributes to organ fibrosis through the production of connective tissue growth factor (CTGF) via actin cytoskeleton-dependent signaling, myocardin-related transcription factor family (MRTF) consisting of MRTF-A and MRTF-B-serum response factor (SRF) pathway. In this study, we investigated the role of the MRTF-SRF pathway in the development of renal fibrosis, focusing on the regulation of ECM-focal adhesions (FA) in renal fibroblasts. Here we showed that both MRTF-A and -B were required for the expressions of ECM-related molecules such as lysyl oxidase family members, type I procollagen and fibronectin in response to transforming growth factor (TGF)-β1 . TGF-β1 -MRTF-SRF pathway induced the expressions of various components of FA such as integrin α subunits (αv , α2 , α11 ) and β subunits (β1 , β3 , β5 ) as well as integrin-linked kinase (ILK). On the other hand, the blockade of ILK suppressed TGF-β1 -induced MRTF-SRF transcriptional activity, indicating a mutual relationship between MRTF-SRF and FA. Myofibroblast differentiation along with CTGF expression was also dependent on MRTF-SRF and FA components. Finally, global MRTF-A deficient and inducible fibroblast-specific MRTF-B deficient mice (MRTF-AKO BiFBKO mice) are protected from renal fibrosis with adenine administration. Renal expressions of ECM-FA components and CTGF as well as myofibroblast accumulation were suppressed in MRTF-AKO BiFBKO mice. These results suggest that the MRTF-SRF pathway might be a therapeutic target for renal fibrosis through the regulation of components forming ECM-FA in fibroblasts.

Copper, Lysyl Oxidase Activity, and Collagen in Aqueous Humour of Primary Glaucoma: An Association with Clinical Parameters

INTRODUCTION

To measure copper (Cu), lysyl oxidase (LOX) activity, and collagen levels in aqueous humour (AH) of primary glaucoma patients and correlate with clinical parameters.

METHODS

120 patients with 40 each of primary open angle glaucoma (POAG), primary angle closure glaucoma (PACG), and cataract controls were recruited in this case-control study. AH samples were collected during the trabeculectomy and cataract surgeries. Cu levels were measured using an atomic absorption spectrophotometer. LOX unit activity was determined by Amplex Red assay and collagen concentration by Sirius red assay.

RESULTS

Significantly higher levels of Cu expressed as median (IQR) µmol/L were observed in POAG (p = 0.008) and PACG (p = 0.005) compared to controls. The LOX activity was increased in POAG and PACG (p = 0.04) compared to controls represented as median (IQR) µmol/min. The collagen levels given as median (IQR) mg/ml showed an insignificant increase in POAG and PACG compared to controls (p = 0.78). The LOX unit activity was correlated with visual field index (VFI), which showed a significant increase with the progression of the diseases (p < 0.05), whereas Cu levels were negatively correlated with LOX activity in AH. Cu and LOX activity showed weak correlation with YAG peripheral iridotomy (YAGPI), duration of anti-glaucoma medications, and highest preoperative intraocular pressure.

CONCLUSION

Elevated Cu and LOX activity was observed in both POAG and PACG groups compared to controls. LOX activity showed notable increase with VFI as the severity of the disease. Although Cu levels are increased in glaucoma, it's insufficient to significantly increase the activity of LOX.

Urinary Copper Excretion Is Associated with Long-Term Graft Failure in Kidney Transplant Recipients

INTRODUCTION

In chronic kidney disease, proteinuria increases urinary copper excretion, inducing oxidative tubular damage and worsening kidney function. We investigated whether this phenomenon occurred in kidney transplant recipients (KTRs). In addition, we studied the associations of urinary copper excretion with the biomarker of oxidative tubular damage urinary liver-type fatty-acid binding protein (u-LFABP) and death-censored graft failure.

METHODS

This prospective cohort study was performed in the Netherlands between 2008 and 2017, including outpatient KTR with a functioning graft for longer than 1 year, who were extensively phenotyped at baseline. Twenty-four-hour urinary copper excretion was measured by inductively coupled plasma mass spectrometry. Multivariable linear and Cox regression analyses were performed.

RESULTS

In 693 KTR (57% men, 53 ± 13 years, estimated glomerular filtration rate [eGFR] 52 ± 20 mL/min/1.73 m2), baseline median urinary copper excretion was 23.6 (interquartile range 11.3-15.9) µg/24 h. Urinary protein excretion was positively associated with urinary copper excretion (standardized β = 0.39, p < 0.001), and urinary copper excretion was positively associated with u-LFABP (standardized β = 0.29, p < 0.001). During a median follow-up of 8 years, 109 (16%) KTR developed graft failure. KTR with relatively high copper excretion were at higher risk of long-term graft failure (hazard ratio [HR]: 1.57, 95% confidence interval [CI]: 1.32-1.86 per log2, p < 0.001), independent of multiple potential confounders like eGFR, urinary protein excretion, and time after transplantation. A dose-response relationship was observed over increasing tertiles of copper excretion (HR: 5.03, 95% CI: 2.75-9.19, tertile 3 vs. 1, p < 0.001). u-LFABP was a significant mediator of this association (74% of indirect effect, p < 0.001).

CONCLUSION

In KTR, urinary protein excretion is positively correlated with urinary copper excretion. In turn, higher urinary copper excretion is associated with an independent increased risk of kidney graft failure, with a substantial mediating effect through oxidative tubular damage. Further studies are warranted to investigate whether copper excretion-targeted interventions could improve kidney graft survival.

Low Level Mancozeb Exposure Causes Copper Bioaccumulation in the Renal Cortex of Rats Leading to Tubular Injury

Mancozeb is a widely-used, broad-spectrum contact dithiocarbamate fungicide. Dithiocarbamates are known to trans-chelate metals. This study was designed to evaluate the potential of Mancozeb to mobilize and bioaccumulate essential trace metals in various tissues. Long-Evans rats were orally gavaged with 0, 50, or 100mg/kg/day of Mancozeb for 28 days. Mancozeb caused a significant increase in copper and manganese in the hippocampus and manganese in the liver. Exceedingly higher level of copper was detected in the renal cortex using ICP-OES in both dose groups. This was confirmed histologically in the tubular epithelial cells. In addition, copper-associated protein levels were also increased. Copper bioaccumulation in the renal cortex was accompanied by oxidative damage and tubular insult indicated by increased 4-HNE, KIM-1, and NGAL immunoreactivity. These findings demonstrate that low-dose Mancozeb exposure is a potential risk for kidney injury due to copper overload and warrants further in vivo and human population-based investigations.

Early events marking lung fibroblast transition to profibrotic state in idiopathic pulmonary fibrosis

BACKGROUND

Idiopathic Pulmonary Fibrosis (IPF) is an age-associated progressive lung disease with accumulation of scar tissue impairing gas exchange. Previous high-throughput studies elucidated the role of cellular heterogeneity and molecular pathways in advanced disease. However, critical pathogenic pathways occurring in the transition of fibroblasts from normal to profibrotic have been largely overlooked.

METHODS

We used single cell transcriptomics (scRNA-seq) from lungs of healthy controls and IPF patients (lower and upper lobes). We identified fibroblast subclusters, genes and pathways associated with early disease. Immunofluorescence assays validated the role of MOXD1 early in fibrosis.

RESULTS

We identified four distinct fibroblast subgroups, including one marking the normal-to-profibrotic state transition. Our results show for the first time that global downregulation of ribosomal proteins and significant upregulation of the majority of copper-binding proteins, including MOXD1, mark the IPF transition. We find no significant differences in gene expression in IPF upper and lower lobe samples, which were selected to have low and high degree of fibrosis, respectively.

CONCLUSIONS

Early events during IPF onset in fibroblasts include dysregulation of ribosomal and copper-binding proteins. Fibroblasts in early stage IPF may have already acquired a profibrotic phenotype while hallmarks of advanced disease, including fibroblast foci and honeycomb formation, are still not evident. The new transitional fibroblasts we discover could prove very important for studying the role of fibroblast plasticity in disease progression and help develop early diagnosis tools and therapeutic interventions targeting earlier disease states.

The Combined Administration of Vitamin C and Copper Induces a Systemic Oxidative Stress and Kidney Injury

Vitamin C (ascorbic acid; AA) and copper (Cu²⁺) are well used supplements with many health-promoting actions. However, when they are used in combination, the Fenton reaction occurs, leading to the formation of highly reactive hydroxyl radicals. Given that kidney is vulnerable to many toxicants including free radicals, we speculated that the in vivo administration of AA plus Cu²⁺ may cause oxidative kidney injury. The purpose of this study was to address this possibility. Mice were administered with AA and Cu²⁺, alone or in combination, via oral gavage once a day for various periods. Changes in the systemic oxidative status, as well renal structure and functions, were examined. The administration of AA plus Cu²⁺ elevated protein oxidation in serum, intestine, bladder, and kidney, as evidenced by the increased sulfenic acid formation and decreased level of free sulfhydryl groups (-SH). The systemic oxidative stress induced by AA plus Cu²⁺ was associated with a significant loss of renal function and structure, as indicated by the increased blood urea nitrogen (BUN), creatinine and urinary proteins, as well as glomerular and tubular cell injury. These effects of AA and Cu²⁺ were only observed when used in combination, and could be entirely prevented by thiol antioxidant NAC. Further analysis using cultured renal tubular epithelial cells revealed that AA plus Cu²⁺ caused cellular protein oxidation and cell death, which could be abolished by NAC and catalase. Moreover, coincubation of AA and Cu²⁺ led to H₂O₂ production. Collectively, our study revealed that a combined administration of AA and Cu²⁺ resulted in systemic oxidative stress and renal cell injury. As health-promoting supplements, AA and Cu²⁺ should not be used together.

Involvement of the inhibition of mitochondrial apoptotic, p53, NF-κB pathways and the activation of Nrf2/HO-1 pathway in the protective effects of curcumin against copper sulfate-induced nephrotoxicity in mice

Chronic copper exposure could cause potential nephrotoxicity and effective therapy strategies are limited. This study investigated the protective effects of curcumin on copper sulfate (CuSO4)-induced renal damage in a mouse model and the underlying molecular mechanisms. Mice were administrated orally with CuSO4 (100 mg/kg per day) in combination with or without curcumin (50, 100 or 200 mg/kg per day, orally) for 28 days. Results showed that curcumin supplementation significantly reduce the Cu accumulation in the kidney tissues of mice and improved CuSO4-induced renal dysfunction. Furthermore, curcumin supplantation also significantly ameliorated Cu exposure-induced oxidative stress and tubular necrosis in the kidneys of mice. Moreover, compared to the CuSO4 alone group, curcumin supplementation at 200 mg/kg per day significantly decreased CuSO4-induced the expression of p53, Bax, IL-1β, IL-6, and TNF-α proteins, levels of NF-κB mRNA, levels of caspases-9 and - 3 activities, and cell apoptosis, and significantly increased the levels of Nrf2 and HO-1 mRNAs in the kidney tissues. In conclusion, for the first time, our results reveal that curcumin could trigger the inhibition of oxidative stress, mitochondrial apoptotic, p53, and NF-κB pathways and the activation of Nrf2/HO-1 pathway to ameliorate Cu overload-induced nephrotoxicity in a mouse model. Our study highlights that curcumin supplementation may be a promising treatment strategy for treating copper overload-caused nephrotoxicity.

Remodeling of imbalanced extracellular matrix homeostasis for reversal of pancreatic fibrosis

Pancreatic fibrosis is mainly manifested by imbalance in extracellular matrix (ECM) homeostasis due to excessive deposition of collagen in pancreas by activated pancreatic stellate cells (PSCs). Recently, some drugs have exhibited therapeutic potentials for the treatment of pancreatic fibrosis; however, currently, no effective clinical strategy is available to remodel imbalanced ECM homeostasis because of inferior targeting abilities of drugs and collagen barriers that hinder the efficient delivery of drugs. Herein, we design and prepare collagen-binding peptide (CBP) and collagenase I co-decorated dual drug-loaded lipid nanoparticles (named AT-CC) for pancreatic fibrosis therapy. Specifically, AT-CC can target fibrotic pancreas via the CBP and degrade excess collagen by the grafted collagenase I, thereby effectively delivering all-trans-retinoic acid (ATRA) and ammonium tetrathiomolybdate (TM) into pancreas. The released ATRA can reduce collagen overproduction by inhibiting the activation of PSCs. Moreover, the released TM can restrain lysyloxidase activation, consequently reducing collagen cross-linking. The combination of ATRA and TM represses collagen synthesis and reduces collagen cross linkages to restore ECM homeostasis. The results of this research suggest that AT-CC is a safe and efficient collagen-targeted degradation drug-delivery system for reversing pancreatic fibrosis. Furthermore, the strategy proposed herein will offer an innovative platform for the treatment of chronic pancreatitis.

Lysyl oxidase-like 4 exerts an atypical role in breast cancer progression that is dependent on the enzymatic activity that targets the cell-surface annexin A2

Background

LOX family members are reported to play pivotal roles in cancer. Unlike their enzymatic activities in collagen cross-linking, their precise cancer functions are unclear. We revealed that LOXL4 is highly upregulated in breast cancer cells, and we thus sought to define an unidentified role of LOXL4 in breast cancer.

Methods

We established the MDA-MB-231 sublines MDA-MB-231-LOXL4 mutCA and -LOXL4 KO, which stably overexpress mutant LOXL4 that loses its catalytic activity and genetically ablates the intrinsic LOXL4 gene, respectively. In vitro and in vivo evaluations of these cells' activities of cancer outgrowth were conducted by cell-based assays in cultures and an orthotopic xenograft model, respectively. The new target (s) of LOXL4 were explored by the MS/MS analytic approach.

Results

Our in vitro results revealed that both the overexpression of mutCA and the KO of LOXL4 in cells resulted in a marked reduction of cell growth and invasion. Interestingly, the lowered cellular activities observed in the engineered cells were also reflected in the mouse model. We identified a novel binding partner of LOXL4, i.e., annexin A2. LOXL4 catalyzes cell surface annexin A2 to achieve a cross-linked multimerization of annexin A2, which in turn prevents the internalization of integrin β-1, resulting in the locking of integrin β-1 on the cell surface. These events enhance the promotion of cancer cell outgrowth.

Conclusions

LOXL4 has a new role in breast cancer progression that occurs via an interaction with annexin A2 and integrin β-1 on the cell surface.

Potential Role of Copper in Diabetes and Diabetic Kidney Disease

Copper is a fundamental element for the homeostasis of the body. It is the third most abundant essential transition metal in humans. Changes in the concentration of copper in the blood are responsible for numerous diseases affecting various organs, including the heart, brain, kidneys, and liver. Even small copper deficiencies can lead to the development and progression of several pathologies. On the other hand, excessive exposure to copper can cause toxicity in many human organs, leading to various systemic alterations. In the kidney, increased copper concentration in the blood can cause deposition of this element in the kidneys, leading to nephrotoxicity. One of the most interesting aspects of copper balance is its influence on diabetes and the progression of its complications, such as Diabetic Kidney Disease (DKD). Several studies have shown a close relationship between copper serum levels and altered glycemic control. An imbalance of copper can lead to the progression of diabetes-related complications and impaired antioxidant homeostasis. A high Zinc/Copper (Zn/Cu) ratio is associated with improved renal function and reduced risk of poor glycemic control in patients with type two diabetes mellitus (T2DM). Furthermore, the progression of DKD appears to be related to the extent of urinary copper excretion, while regulation of adequate serum copper concentration appears to prevent and treat DKD. The aim of this review is to evaluate the possible role of copper in DKD patients.

Appropriate level of cuproptosis may be involved in alleviating pulmonary fibrosis

Objective

Cuproptosis is a newly discovered form of programmed cell death that has not been studied in pulmonary fibrosis. The purpose of the present study was to explore the relationship between cuproptosis and pulmonary fibrosis.

Methods

Single-cell sequencing (scRNA-seq) data for human and mouse pulmonary fibrosis were obtained online from Gene Expression Omnibus (GEO) database. First, fibroblast lineage was identified and extracted using the Seurat toolkit. The pathway was then evaluated via Gene Set Enrichment Analyses (GSEA), while transcription factor activity was analyzed using DoRothEA. Next, fibroblast differentiation trajectory was inferred via Monocle software and changes in gene expression patterns during fibroblast activation were explored through gene dynamics analysis. The trajectory was then divided into three cell states in pseudotime order and the expression level of genes related to cuproptosis promotion in each cell state was evaluated, in addition to genes related to copper export and buffering and key genes in cellular metabolic pathways.

Results

In the mouse model of pulmonary fibrosis induced by bleomycin, the genes related to cuproptosis promotion, such as Fdx1, Lias, Dld, Pdha1, Pdhb, Dlat, and Lipt1, were gradually down-regulated in the process of fibroblast differentiation from resting fibroblast to myofibroblast. Consistently, the same results were obtained via analysis of scRNA-seq data for human pulmonary fibrosis. In addition, genes related to copper ion export and buffering gradually increased with the activation of fibroblasts. Metabolism reprogramming was also observed, while fibroblast activation and tricarboxylic acid(TCA) cycle and lipid metabolism were gradually down-regulated and mitochondrial metabolism was gradually up-regulated.

Conclusion

The present study is the first to reveal a negative correlation between cuproptosis and fibrosis, suggesting that an appropriate cuproptosis level may be involved in inhibiting fibroblast activation. This may provide a new method for the treatment of pulmonary fibrosis.

Benefits and risks of essential trace elements in chronic kidney disease: a narrative review

Background and Objective

Chronic kidney disease (CKD) is an important public health concern. With the decline of renal function, CKD patients gradually progress to end-stage kidney disease and need to undergo dialysis or kidney transplantation to maintain life, bringing a heavy economic burden to the family and society. Therefore, it is necessary to effectively prevent and delay the progression of CKD. Essential trace elements play an indispensable role in CKD, and the objective of this study is to systematically review their benefits in the disease and summarize the risks of their excess.

Methods

The keywords "trace elements", "chronic kidney disease", "dialysis", "inflammation", and "fibrosis" and their combinations were used to search for relevant literature published in the PubMed database and Web of Science. We then summarized the role of trace element abnormalities in CKD patients in anemia, oxidative stress, inflammation, and chronic fibrosis, and the risk of their excess.

Key Content and Findings

Imbalance of essential trace elements is a common complication of CKD and a risk factor for CKD progression, cardiovascular events, and death. This article reviews the effects of essential trace elements (iron, zinc, selenium, copper, iodine, and manganese) on CKD. We analyze literature and discuss the advantages and disadvantages of various essential trace elements.

Conclusions

Research shows CKD patients have an imbalance of essential trace elements, and treatment based on these is an important direction for future exploration. A knowledge of the homeostasis of trace elements is important to improving the prognosis of CKD patients and delaying the progression of the disease.

Association of copper exposure with prevalence of chronic kidney disease in older adults

BACKGROUND & AIMS

Metal exposure is suspected to be associated with the risk of chronic kidney disease (CKD). Copper (Cu) is an essential yet toxic trace element in humans. Epidemiological evidence on the association of Cu exposure with CKD remains inconsistent. This study aims to investigate the association of blood Cu and its co-exposure to other metals with CKD.

METHODS

A cross-sectional study was conducted among 3285 older participants in Zhejiang, China. The whole blood levels of Cu as well as other 10 metals were measured using the inductively coupled plasma mass spectrometry (ICP-MS). CKD events were defined as the presence of albuminuria or estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m². Multivariable logistic regression and linear regression models were applied to assess the association of Cu with kidney function. The Bayesian kernel machine regression (BKMR) was used to examine the association of metal interactions with CKD.

RESULTS

In logistic models, we found a dose-dependent positive association between blood Cu and the prevalence of CKD. Compared to the lowest quartile of blood Cu, the odds ratio (OR) of CKD in the highest quartile was 1.65 (95% confidence interval, CI: 1.25, 2.17), and the β of eGFR was -1.74 (95% CI: -3.15, -0.34) after adjusting for multiple covariates. The positive linear dose-response association was found between blood Cu and the OR of CKD, and negative linear association was found between Cu and the β of eGFR. The positive association between blood Cu and CKD risk was stronger at lower level of manganese (Mn) in the BKMR model.

CONCLUSION

The whole blood level of Cu was remarkably associated with the risk of CKD and showed positive dose-response relationships in the older Chinese population. The toxicity of Cu on kidney function could be antagonized by the exposure of Mn. These findings shed new light on the potential role of Cu in kidney health.

Identification of key cuproptosis-related genes and their targets in patients with IgAN

BACKGROUND

IgA nephropathy (IgAN) is one of the most common forms of chronic glomerulonephritis, but the aetiology and pathogenesis remain unclear. Cuproptosis is a newly identified form of cell death that plays an important role in many diseases. Researchers have not clearly determined whether the expression of cuproptosis-related genes (CRGs) is involved in the pathogenesis of IgAN.

METHODS

The GSE93798, GSE50469 and GSE37460 datasets containing microarray data from patients with IgAN (63) and healthy controls (31) were downloaded from the GEO database. Immune cells and immune-related functions were analysed in patients with IgAN and controls, and genes were identified that may be related to cuproptosis. A logistic regression model was established according to the results, and then GO and KEGG enrichment analyses were performed. Finally, possible drugs were selected using the DSigDB database.

RESULTS

The subjects in the different groups showed significantly different fractions of immune cells and immune-related functions, and 11 genes related to cuproptosis may be involved in these processes. Based on these 11 genes, the ROC curve was plotted, and the AUC value was calculated (0.898, 95% CI: 0.839-0.958). The result revealed good predictability. Then, genes with P &lt; 0.05 (lipoyltransferase 1, LIPT1) were selected to plot an ROC curve, and the AUC value was calculated (0.729, 95% CI: 0.636-0.821). Enrichment analyses showed that the TCA cycle and multiple metabolic pathways may also be involved in the occurrence of IgAN. Finally, 293 potential drugs that may be used to treat IgAN were identified based on these genes.

CONCLUSION

In this study, we identified some novel CRGs that may be involved in IgAN, among which LIPT1 was significantly differentially expressed. It may predict the risk of IgAN and provides a possible target for the treatment of IgAN. Further experimental studies are needed to explore how these CRGs mediate the occurrence and development of IgAN.

An Overview of Methods and Exemplars of the Use of Mendelian Randomisation in Nutritional Research

Objectives: It is crucial to elucidate the causal relevance of nutritional exposures (such as dietary patterns, food intake, macronutrients intake, circulating micronutrients), or biomarkers in non-communicable diseases (NCDs) in order to find effective strategies for NCD prevention. Classical observational studies have found evidence of associations between nutritional exposures and NCD development, but such studies are prone to confounding and other biases. This has direct relevance for translation research, as using unreliable evidence can lead to the failure of trials of nutritional interventions. Facilitated by the availability of large-scale genetic data, Mendelian randomization studies are increasingly used to ascertain the causal relevance of nutritional exposures and biomarkers for many NCDs. Methods: A narrative overview was conducted in order to demonstrate and describe the utility of Mendelian randomization studies, for individuals with little prior knowledge engaged in nutritional epidemiological research. Results: We provide an overview, rationale and basic description of the methods, as well as strengths and limitations of Mendelian randomization studies. We give selected examples from the contemporary nutritional literature where Mendelian randomization has provided useful evidence on the potential causal relevance of nutritional exposures. Conclusions: The selected exemplars demonstrate the importance of well-conducted Mendelian randomization studies as a robust tool to prioritize nutritional exposures for further investigation.

Lysyl oxidase promotes renal fibrosis via accelerating collagen cross-link driving by β-arrestin/ERK/STAT3 pathway

Lysyl oxidase (LOX) is a copper‐dependent monoamine oxidase whose primary function is the covalent cross‐linking of collagen in the extracellular matrix (ECM). Evidence has shown that LOX is associated with cancer and some fibrotic conditions. We recently found that serum LOX is a potential diagnostic biomarker for renal fibrosis, but the mechanism by which LOX is regulated and contributes to renal fibrosis remains unknown. The current study demonstrates the following: (1) LOX expression was increased in fibrotic kidneys including ischemia‐reperfusion injury‐(IRI‐), unilateral ureteral obstruction‐(UUO‐), and folic acid‐ (FA‐) induced fibrotic kidneys as well as in the paraffin‐embedded sections of human kidneys from the patients with renal fibrosis. (2) The increasing deposition and cross‐linking of collagen induced by LOX was observed in IRI‐, UUO‐ and FA‐kidneys. (3) LOX was regulated by the β‐arrestin‐ERK‐STAT3 pathway in renal fibrosis. STAT3 was the downstream of AT1R‐β‐arrestin‐ERK, ERK entered the nucleus and activated STAT3‐pY705 but not STAT3‐pS727. (4) STAT3 nuclear subtranslocation and binding to the LOX promoter may be responsible for the upregulation of LOX expression. (5) Pharmacologic inhibition of LOX with BAPN in vivo inhibited the upregulation of LOX, decreased collagen over cross‐linking and ameliorated renal fibrosis after ischemic injury. Collectively, these observations suggest that LOX plays an essential role in the development of renal fibrosis by catalyzing collagen over cross‐linking. Thus, strategies targeting LOX could be a new avenue in developing therapeutics against renal fibrosis.

Copper chelation therapy inhibits renal fibrosis by modulating copper transport proteins

The copper (Cu) transporter proteins play an important role in the maintenance of the Cu homeostasis in the body. Lysyl oxidase (LOX) proteins are involved in crosslinking of collagens and elastin molecules resulting in the establishment of extracellular matrix (ECM) and require Cu for their functional activity. Although there are few reports showing the protective effects of Cu chelators, the mechanism behind protection remains unknown. The present study investigated the role of Cu transporter proteins in renal fibrosis. We used tubular epithelial cells and three different animal models of renal injury to investigate the induction of Cu transporter proteins in renal injury with different etiology. We used disulfiram, clioquinol as two Cu chelators and ammonium tetrathiomolybdate as a standard Cu chelator. In addition, β-aminopropionitrile (BAPN) was used as a standard LOX inhibitor. We demonstrated that renal fibrosis is associated with the induction of Cu transporter proteins such as ATP7A and Copper Transporter 1 (CTR1) but the Cu overload did not induce renal fibrosis. In addition, the Cu chelators inhibited renal fibrosis by inhibiting the Cu transporter proteins.

Disulfiram prevents collagen crosslinking and inhibits renal fibrosis by inhibiting lysyl oxidase enzymes

Chronic kidney disease is one of the major health burdens affecting a considerable number of people worldwide. The aberrant regulation of lysyl oxidase (LOX) family of enzymes results in establishment of dense extracellular matrix (ECM). Since, LOX enzymes need copper (Cu) for their proper catalytic activity; the present study investigated the efficacy of a copper chelator, disulfiram (DSF) in renal fibrosis. Antifibrotic activity of DSF was investigated in kidney epithelial cells stimulated by transforming growth factor-β1 (5 ng/ml) as well as in two animal models. The renal injury was induced in animals by unilateral ureteral obstruction and folic acid administration (250 mg/kg). The DSF (3 and 10 mg/kg, every 3rd day) and standard LOX inhibitor, β-aminopropionitrile (BAPN, 100 mg/kg, daily) administration was started on day 0 and continued till the day of sacrifice. DSF was found to be a potent LOX/LOXL2 inhibitor to reduce crosslinking of collagen fibrils leading to reduction in the collagen deposition. In addition, the DSF was demonstrated to inhibit epithelial-mesenchymal transition in the tubular cells and fibrotic kidneys. Our results suggested that DSF, being a clinically available drug could be translated to clinics for its potent antifibrotic activity due to its inhibitory effect on LOX proteins.

Genetically Predicted Circulating Copper and Risk of Chronic Kidney Disease: A Mendelian Randomization Study

Elevated circulating copper levels have been associated with chronic kidney disease (CKD), kidney damage, and decline in kidney function. Using a two sample Mendelian randomization approach where copper-associated genetic variants were used as instrumental variables, genetically predicted higher circulating copper levels were associated with higher CKD prevalence (odds ratio 1.17; 95% confidence interval 1.04, 1.32; p-value = 0.009). There was suggestive evidence that genetically predicted higher copper was associated with a lower estimated glomerular filtration rate and a more rapid kidney damage decline. In conclusion, we observed that elevated circulating copper levels may be a causal risk factor for CKD.

LncRNA GAS5 protects against TGF-β-induced renal fibrosis via the Smad3/miRNA-142-5p axis

Increasing evidence shows that long noncoding RNAs (lncRNAs) play an important role in kidney disease. In this study, we investigated the role of the lncRNA growth arrest-specific 5 (GAS5) in the pathogenesis of renal fibrosis. We found that GAS5 was markedly decreased in the fibrotic kidney of a unilateral ureteral obstructive nephropathy mouse model. In addition, GAS5 was expressed in mouse tubular epithelial cells (mTECs) and interstitial fibroblasts in normal renal tissue and was especially highly expressed in the cytoplasm. In vitro experiments showed that GAS5 was downregulated by transforming growth factor-β1 (TGF-β1) in a dose- and time-dependent manner. Overexpression of GAS5 blocked TGF-β1-induced collagen type I and fibronectin expression and vice versa. Mechanistic experiments revealed that Smad3 but not Smad2 drove the regulation of GAS5. More importantly, GAS5 interacted with miR-142-5p and was involved in the renoprotective effect by participating in the competing endogenous RNA network. Finally, we also found that knockdown of GAS5 promoted TGF-β1-induced mouse tubular epithelial cell apoptosis via the Smad3 pathway. Taken together, our results uncovered a lncRNA/miRNA competing endogenous RNA network-based mechanism that modulates extracellular matrix formation and cell apoptosis via the Smad3 pathway.NEW & NOTEWORTHY In this work, we mainly discuss long noncoding RNA growth arrest-specific 5 (GAS5), acting in a renoprotective role via the Smad3/miRNA-142-5p axis, that modulates extracellular matrix formation and cell apoptosis. Overexpression of GAS5 effectively blocked renal fibrosis in vitro. This study reveals that GAS5 may represent as a novel and precision therapeutic target for alleviating renal fibrosis.

Selective depletion of hepatic stellate cells-specific LOXL1 alleviates liver fibrosis

The role of LOXL1 in fibrosis via mediating ECM crosslinking and stabilization is well established; however, the role of hepatic stellate cells (HSCs)-specific LOXL1 in the development of fibrosis remains unknown. We generated HSCs-specific Loxl1-depleted mice (Loxl1^Gfap-cre mice) to investigate the HSCs-specific contribution of LOXL1 in the pathogenesis of fibrosis. Loxl1^fl/fl mice were used as the control. Furthermore, we used RNA sequencing to explore the underlying changes in the transcriptome. Results of the sirius red staining, type I collagen immunolabeling, and hydroxyproline content analysis, coupled with the reduced expression of profibrogenic genes revealed that Loxl1^Gfap-cre mice with CCl₄ -induced fibrosis exhibited decreased hepatic fibrosis. In addition, Loxl1^Gfap-cre mice exhibited reduced macrophage tissue infiltration by CD68-positive cells and decreased expression of inflammatory genes compared with the controls. RNA sequencing identified integrin α8 (ITGA8) as a key modulator of LOXL1-mediated liver fibrosis. Functional analyses showed that siRNA silencing of Itga8 in cultured fibroblasts led to a decline in the LOXL1 expression and inhibition of fibroblast activation. Mechanistic analyses indicated that LOXL1 activated the FAK/PI3K/AKT/HIF1a signaling pathway, and the addition of inhibitors of FAK or PI3K reversed these results via downregulation of LOXL1. Furthermore, HIF1a directly interacted with LOXL1 and upregulated its expression, indicating that LOXL1 can positively self-regulate by forming a positive feedback loop with the FAK/PI3K/AKT/HIF1a pathway. We demonstrated that HSCs-specific Loxl1 deficiency prevented fibrosis, inflammation and that ITGA8/FAK/PI3K/AKT/HIF1a was essential for the function and expression of LOXL1. Knowledge of this approach can provide novel mechanisms and targets to treat fibrosis in the future.

LOXL2 Inhibitors and Breast Cancer Progression

LOX (lysyl oxidase) and lysyl oxidase like-1–4 (LOXL 1–4) are amine oxidases, which catalyze cross-linking reactions of elastin and collagen in the connective tissue. These amine oxidases also allow the cross-link of collagen and elastin in the extracellular matrix of tumors, facilitating the process of cell migration and the formation of metastases. LOXL2 is of particular interest in cancer biology as it is highly expressed in some tumors. This protein also promotes oncogenic transformation and affects the proliferation of breast cancer cells. LOX and LOXL2 inhibition have thus been suggested as a promising strategy to prevent metastasis and invasion of breast cancer. BAPN (β-aminopropionitrile) was the first compound described as a LOX inhibitor and was obtained from a natural source. However, novel synthetic compounds that act as LOX/LOXL2 selective inhibitors or as dual LOX/LOX-L inhibitors have been recently developed. In this review, we describe LOX enzymes and their role in promoting cancer development and metastases, with a special focus on LOXL2 and breast cancer progression. Moreover, the recent advances in the development of LOXL2 inhibitors are also addressed. Overall, this work contextualizes and explores the importance of LOXL2 inhibition as a promising novel complementary and effective therapeutic approach for breast cancer treatment.

Lysyl oxidases: Emerging biomarkers and therapeutic targets for various diseases

Therapeutic targeting of extracellular proteins has attracted huge attention in treating human diseases. The lysyl oxidases (LOXs) are a family of secreted copper-dependent enzymes which initiate the covalent crosslinking of collagen and elastin fibers in the extracellular microenvironment, thereby facilitating extracellular matrix (ECM) remodeling and ECM homeostasis. Apart from ECM-dependent roles, LOXs are also involved in other biological processes such as epithelial-to-mesenchymal transition (EMT) and transcriptional regulation, especially following hypoxic stress. Dysregulation of LOXs is found to underlie the onset and progression of multiple pathologies, such as carcinogenesis and cancer metastasis, fibrotic diseases, neurodegeneration and cardiovascular diseases. In this review, we make a comprehensive summarization of clinical and experimental evidences that support roles of for LOXs in disease pathology and points out LOXs as promising therapeutic targets for improving prognosis. Additionally, we also propose that LOXs reshape cell-ECM interaction or cell-cell interaction due to ECM-dependent and ECM-independent roles for LOXs. Therapeutic intervention of LOXs may have advantages in the maintenance of communication between ECM and cell or intercellular signaling, finally recovering organ function.