Endoplasmic reticulum stress, the unfolded protein response and autophagy in kidney diseases

Xuebijing injection alleviates septic acute kidney injury by modulating inflammation, mitochondrial dysfunction, and endoplasmic reticulum stress

BACKGROUND

Xuebijing (XBJ) injection has been used to treat sepsis. However, the effect and mechanism of XBJ injection in the treatment of septic acute kidney injury (AKI) is unknown. This study aimed to explore the therapeutic effect of XBJ injection on septic AKI and elucidate its possible mechanisms.

METHODS

Network pharmacological analysis was conducted using databases of GeneCards, TCMSP, SwissTargetPrediction and STRING. In vivo, a septic AKI model was established in C57BL/6 mice by cecal ligation and puncture (CLP). The groups were Sham, XBJ, CLP, and CLP + XBJ (10 mL/kg IV) (n = 5). Tubular damage, renal function, and levels of inflammation and apoptosis in the kidneys were evaluated. In vitro model was lipopolysaccharide (LPS, 100 μg/mL) stimulated HK-2 cells. The groups were PBS, XBJ, LPS, and LPS + XBJ (XBJ injected at 10 dilutions). Cell viability, apoptosis, inflammation, mitochondrial function and, endoplasmic reticulum (ER) stress were also assessed.

RESULTS

Network pharmacological analysis identified Toll like receptor 4 (TLR4) as the core gene in XBJ against septic AKI, and the inflammatory response was the most enriched pathway. XBJ treatment significantly alleviated tubular damage in CLP mice by down-regulating serum creatinine (SCr), blood urea nitrogen (BUN), kidney injury molecule 1 (KIM1), and neutrophil gelatinase-associated lipocalin (NGAL). Furthermore, both in vivo and in vitro experiments demonstrated that XBJ treatment could inhibit apoptosis, inflammation, mitochondrial dysfunction, and ER stress via TLR4/MyD88/NF-κB axis.

CONCLUSION

This study indicates that XBJ injection is a promising drug for the treatment of septic AKI.

Protein handling in kidney tubules

The kidney proximal tubule reabsorbs and degrades filtered plasma proteins to reclaim valuable nutrients and maintain body homeostasis. Defects in this process result in proteinuria, one of the most frequently used biomarkers of kidney disease. Filtered proteins enter proximal tubules via receptor-mediated endocytosis and are processed within a highly developed apical endo-lysosomal system (ELS). Proteinuria is a strong risk factor for chronic kidney disease progression and genetic disorders of the ELS cause hereditary kidney diseases, so deepening understanding of how the proximal tubule handles proteins is crucial for translational nephrology. Moreover, the ELS is both an entry point for nephrotoxins that induce tubular damage and a target for novel therapies to prevent it. Cutting-edge research techniques, such as functional intravital imaging and computational modelling, are shedding light on spatial and integrative aspects of renal tubular protein processing in vivo, how these are altered under pathological conditions and the consequences for other tubular functions. These insights have potentially important implications for understanding the origins of systemic complications arising in proteinuric states, and might lead to the development of new ways of monitoring and treating kidney diseases.

Fisetin reverses the negative effect of Lambda-Cyhalothrin on the maturation process of porcine oocytes in vitro by downregulating GRP78 levels

Lambda-Cyhalothrin (LCT), a potent insecticide, is renowned for its efficacy, rapid onset, and broad-spectrum insecticidal activity. With rising annual demand for LCT, environmental concerns have similarly intensified. Nevertheless, its impact on mammalian reproduction, specifically oocytes, and possible mitigation strategies, remains insufficiently understood. This research evaluated the effects of varying LCT concentrations (25, 50, 100 μM) on the in vitro maturation of porcine oocytes, revealing that LCT exposure markedly hindered oocyte maturation and subsequent developmental potential. Fisetin (FIS), a natural flavonoid found in numerous fruits and vegetables, exhibits robust antioxidant, anti-inflammatory, and neuroprotective properties. Notably, when different concentrations of FIS were incorporated into the culture medium of LCT-exposed oocytes, it mitigated LCT-induced toxicity. FIS supplementation significantly enhanced antioxidant capacity, improved endoplasmic reticulum (ER) and mitochondrial functions, and reduced apoptosis in comparison to the LCT-exposed group. Key markers, including the ER stress protein GRP78 (Control: 1.00 vs. LCT: 1.75 ± 0.08, P < 0.001; vs. LCT + FIS: 1.37 ± 0.07, P < 0.001) and autophagy marker LC3B (Control: 1.00 vs. LCT: 1.50 ± 0.32, P < 0.05; vs. LCT + FIS: 1.18 ± 0.16, P > 0.05), were significantly reduced in the FIS-treated oocytes. These results suggest that LCT compromises mitochondrial and ER function in oocytes through the upregulation of GRP78, while FIS supplementation effectively counteracts this toxicity, providing protection against LCT-induced damage. This study underscores FIS's potential as a protective agent in alleviating LCT-related reproductive toxicity.

TRIB3 mediates vascular calcification by facilitating self-ubiquitination and dissociation of Smurf1 in chronic kidney disease

The osteogenic environment promotes vascular calcium phosphate deposition and aggregation of unfolded and misfolded proteins, resulting in ER stress in chronic kidney disease (CKD). Controlling ER stress through genetic intervention is a promising approach for treating vascular calcification. In this study, we demonstrated a positive correlation between ER stress-induced tribble homolog 3 (TRIB3) expression and progression of vascular calcification in human and rodent CKD. Increased TRIB3 expression promoted vascular smooth muscle cell (VSMC) calcification by interacting with the C2 domain of the E3 ubiquitin-protein ligase Smurf1, facilitating its K48-related self-ubiquitination at Lys381 and Lys383 and subsequent dissociation from the plasma membrane and nuclei. This degeneration of Smurf1 accelerated the stabilization of the osteogenic transcription factors RUNX family transcription factor 2 (Runx2) and SMAD family member 1 (Smad1). C/EBP homologous protein and activating transcription factor 4 are upstream transcription factors of TRIB3 in an osteogenic environment. Genetic KO of TRIB3 or rescue of Smurf1 ameliorated VSMC and vascular calcification by stabilizing Smurf1 and enhancing the degradation of Runx2 and Smad1. Our findings shed light on the vital role of TRIB3 as a scaffold in ER stress and vascular calcification and offer a potential therapeutic option for CKD.

Endoplasmic reticulum stress and unfolded protein response: Roles in skeletal muscle atrophy

Skeletal muscle atrophy is commonly present in various pathological states, posing a huge burden on society and patients. Increased protein hydrolysis, decreased protein synthesis, inflammatory response, oxidative stress, mitochondrial dysfunction, endoplasmic reticulum stress (ERS) and unfolded protein response (UPR) are all important molecular mechanisms involved in the occurrence and development of skeletal muscle atrophy. The potential mechanisms of ERS and UPR in skeletal muscle atrophy are extremely complex and have not yet been fully elucidated. This article elucidates the molecular mechanisms of ERS and UPR, and discusses their effects on different types of muscle atrophy (muscle atrophy caused by disuse, cachexia, chronic kidney disease (CKD), diabetes mellitus (DM), amyotrophic lateral sclerosis (ALS), spinal muscular atrophy (SMA), spinal and bulbar muscular atrophy (SBMA), aging, sarcopenia, obesity, and starvation), and explores the preventive and therapeutic strategies targeting ERS and UPR in skeletal muscle atrophy, including inhibitor therapy and drug therapy. This review aims to emphasize the importance of endoplasmic reticulum (ER) in maintaining skeletal muscle homeostasis, which helps us further understand the molecular mechanisms of skeletal muscle atrophy and provides new ideas and insights for the development of effective therapeutic drugs and preventive measures for skeletal muscle atrophy.

Ferroptosis contributed to endoplasmic reticulum stress in preterm birth by targeting LHX1 and IRE-1

Preterm birth (PTB) significantly contributed to neonatal mortality, emphasizing the need for a detailed understanding of its pathogenesis. This study aimed to explore the involvement of ferroptosis, an iron-dependent cell death process, in PTB and investigated the possible crosstalk with endoplasmic reticulum stress (ERS). First, we explored the occurrence of ferroptosis in placenta samples from PTB parturients. Then we established a ferroptosis cell model was established by subjecting trophoblast cells to hypoxia/reoxygenation (H/R), and found the ERS was induced in H/R exposed cells and was attenuated by ferroptosis inhibition using Fer-1, suggesting that ferroptosis could induce ERS. Meanwhile, we also induced ERS in trophoblast cells via tunicamycin (TM) treatment. Ferroptosis inhibition with Fer-1 alleviated TM-induced ER stress. TM treatment reduced trophoblast cell viability and migration while promoted apoptosis and autophagy, effects that were reversed by ferroptosis inhibition. Thus, targeting ferroptosis might help mitigate ER stress-related pathophysiological changes in PTB. Mechanically, we found two ERS mediators LIM homeobox 1 (LHX1)/Inositol-requiring enzyme 1 (IRE-1) were also upregulated in H/R treated cells. Silencing LHX1 or IRE-1 was demonstrated to reverse the H/R-induced ferroptosis. Additionally, rescue assays further revealed that LHX1 promoted ferroptosis by regulating IRE-1. In conclusion, ferroptosis contributed to ERS and was critically involved in PTB, highlighting the LHX1/IRE-1 axis as a promising therapeutic target for mitigating ferroptosis-related complications. These findings offered a foundation for innovative interventions in preterm birth.

Nafamostat Mesylate Regulates Glycosylation to Alleviate Aristolochic Acid Induced Kidney Injury

Acute kidney injury (AKI) is a condition with a poor prognosis, exacerbated by the lack of effective therapeutic options and inadequately understood underlying mechanisms. Glycosylation, a post-translational modification of proteins, is essential for maintaining protein stability and function, and its dysregulation leads to protein misfolding and amyloid aggregation. Glycosylation dynamics are implicated in several pathologies, including inflammation, cancer, and AKI, highlighting the therapeutic potential of regulating glycosylation and preventing aggregation in AKI treatment. This study investigates the effect of nafamostat mesylate (NM) on protein glycosylation and amyloid aggregation in vivo. Using optical spectroscopy and other analytical techniques, we demonstrate that NM restores glycosylation levels and inhibits protein aggregation in aristolochic-acid-induced acute kidney injury. The mechanism likely involves enzymatic modulation that corrects hypoglycosylation and prevents amyloid aggregation, promoting proper protein folding and enhancing its stability. These findings suggest that NM may provide a novel therapeutic strategy for AKI and other glycosylation-related diseases, underscoring the potential for early intervention and treatment of these conditions.

Endoplasmic Reticulum Stress in Myometrial Smooth Muscle Cells and Spontaneous Contraction Changes in the Uterus of Dehydroepiandrosterone-induced Polycystic Ovary Syndrome Rats

Myometrial changes in polycystic ovary syndrome (PCOS) are poorly investigated. Thus, we aimed to investigate endoplasmic reticulum (ER) stress in myometrial smooth muscle cells and changes in spontaneous uterine contraction in PCOS. Twenty-one female Sprague-Dawley rats (21 days old) were divided into control (n = 7), vehicle (n = 7) and PCOS (n = 7) groups. While the control group was not injected subcutaneously, the vehicle group was injected subcutaneously with sesame oil (0.2 ml/day) for 20 consecutive days. The PCOS group was injected subcutaneously with dehydroepiandrosterone (6 mg/100 g/day dissolved in 0.2 ml sesame oil) for 20 consecutive days. Blood samples were collected for the measurement of follicle stimulating-hormone (FSH), luteinizing hormone (LH), testosterone (T), estradiol (E2) and glucose-regulated protein 78 (GRP78). The mRNA expression of GRP78 in the uterine tissue samples was analysed by quantitative real-time polymerase chain reaction. GRP78 protein expression was assessed by immunohistochemistry. Myometrial smooth muscle cells were examined by transmission electron microscopy. Uterine contractions were evaluated with isolated organ bath experiments. In the PCOS group, T and LH levels increased significantly, although FSH and E2 levels decreased, but this decrease was not statistically significant. Additionally, GRP78 levels increased significantly in the PCOS group. In the PCOS group, the mRNA level, immunostaining intensity of GRP78, and ER damage grade increased, but the uterine tissue calcium levels, and the frequency and amplitude of spontaneous uterine contractions decreased. The results indicated that increased ER stress in myometrial smooth muscle cells may play a causative role in the decreased spontaneous uterine contractions in PCOS.

Endoplasmic reticulum stress and unfolded protein response in renal lipid metabolism

The endoplasmic reticulum (ER) is a crucial cellular organelle involved in protein synthesis, folding, modification, and transport. Exposure to internal and external stressors can induce endoplasmic reticulum stress (ERS), leading to abnormal protein folding and ER malfunction. This stress can disrupt lipid synthesis, metabolism, and transport processes. Fatty acid oxidation is the primary energy source for the renal system. When energy intake exceeds the storage capacity of adipose tissue, lipids accumulate abnormally in non-adipose tissues, including kidneys, liver, and pancreas. Lipids accumulate in the kidneys of nearly all cell types, including thylakoid membranous, pedunculated, and proximal renal tubular epithelial cells. Intracellular free fatty acids can significantly disrupt renal lipid metabolism, contributing to ischemia-reperfusion acute kidney injury, diabetic nephropathy, renal fibrosis, and lupus nephritis. Consequently, this study delineated the primary signaling pathways and mechanisms of the ERS-induced unfolded protein response, explored the mechanistic link between ERS and lipid metabolism, and elucidated its role in renal lipid metabolism. This study aimed to offer new perspectives on managing and treating renal disorders.

Endoplasmic reticulum stress as a driver and therapeutic target for kidney disease

The endoplasmic reticulum (ER) has crucial roles in metabolically active cells, including protein translation, protein folding and quality control, lipid biosynthesis, and calcium homeostasis. Adverse metabolic conditions or pathogenic genetic variants that cause misfolding and accumulation of proteins within the ER of kidney cells initiate an injurious process known as ER stress that contributes to kidney disease and its cardiovascular complications. Initiation of ER stress activates the unfolded protein response (UPR), a cellular defence mechanism that functions to restore ER homeostasis. However, severe or chronic ER stress rewires the UPR to activate deleterious pathways that exacerbate inflammation, apoptosis and fibrosis, resulting in kidney injury. This insidious crosstalk between ER stress, UPR activation, oxidative stress and inflammation forms a vicious cycle that drives kidney disease and vascular damage. Furthermore, genetic variants that disrupt protein-folding mechanisms trigger ER stress, as evidenced in autosomal-dominant tubulointerstitial kidney disease and Fabry disease. Emerging therapeutic strategies that enhance protein-folding capacity and reduce the burden of ER stress have shown promising results in kidney diseases. Thus, integrating knowledge of how genetic variants cause protein misfolding and ER stress into clinical practice will enhance treatment strategies and potentially improve outcomes for various kidney diseases and their vascular complications.

Shrimp Shapes a Nitrite Tolerance Trait via Regulating Autophagy and Apoptosis

Nitrite is a significant toxic substance that causes acute toxicity in aquatic animals. However, the molecular mechanisms underlying nitrite tolerance remain largely unidentified. Here, we investigated the physiological and transcriptomic profiles of nitrite-sensitive and nitrite-tolerant families of the white shrimp Penaeus vannamei under nitrite stress. Exposure to a lethal concentration of nitrite for 72 h caused higher mortality, higher nitrite accumulation, and more severe physiological damage in both the hemolymph and hepatopancreas of nitrite-sensitive families than in nitrite-tolerant families. This damage manifested as hepatic tubular deformation, hepatocyte necrosis, decreased hemocyte counts, lowered phagocytic activity in hemocytes, elevated production of reactive oxygen species (ROS), and decreased AKP enzyme activity. Furthermore, transcriptomic analysis revealed an upregulation in protein processing in the endoplasmic reticulum (ER) in the nitrite-tolerant families, triggering apoptosis- and autophagy-related pathways in the hemocytes and hepatopancreas upon nitrite exposure. Additionally, TUNEL staining and transmission electron microscopy (TEM) experiments revealed that the tolerant families may mitigate nitrite toxicity by modulating autophagy and apoptosis. Collectively, our results provide a valuable foundation for exploring the molecular mechanisms underlying nitrite tolerance in shrimp, which could facilitate the targeted breeding of shrimp germplasm with enhanced nitrite tolerance in aquaculture.

NRF-mediated autophagy and UPR: Exploring new avenues to overcome cancer chemo-resistance

The development of chemo-resistance remains a significant hurdle in effective cancer therapy. NRF1 and NRF2, key regulators of redox homeostasis, play crucial roles in the cellular response to oxidative stress, with implications for both tumor growth and resistance to chemotherapy. This study delves into the dualistic role of NRF2, exploring its protective functions in normal cells and its paradoxical support of tumor survival and drug resistance in cancerous cells. We investigate the interplay between the PERK/NRF signaling pathway, ER stress, autophagy, and the unfolded protein response, offering a mechanistic perspective on how these processes contribute to chemoresistance. Our findings suggest that targeting NRF signaling pathways may offer new avenues for overcoming resistance to chemotherapeutic agents, highlighting the importance of a nuanced approach to redox regulation in cancer treatment. This research provides a molecular basis for the development of NRF-targeted therapies, potentially enhancing the efficacy of existing cancer treatments and offering hope for more effective management of resistant tumors.

Genotype-Based Molecular Mechanisms in Alport Syndrome

Alport syndrome is an inherited disorder characterized by kidney disease, sensorineural hearing loss, and ocular abnormalities. Alport syndrome is caused by pathogenic variants in COL4A3 , COL4A4 , or COL4A5 , which encode the α 3, α 4, and α 5 chains of type 4 collagen that forms a heterotrimer expressed in the glomerular basement membrane. Knowledge of its genetic basis has informed the development of different models in dogs, mice, and rats that reflect its autosomal and X-linked inheritance patterns as well as different mutation types, including protein-truncating and missense variants. A key difference between these two types is the synthesis of α 3 α 4 α 5(IV), which is not made in autosomal Alport syndrome (two pathogenic variants in trans or biallelic) or male patients with X-linked Alport syndrome due to protein-truncating variants. By contrast, α 3 α 4 α 5(IV) is synthesized in Alport syndrome because of missense variants. For missense variants, in vitro studies suggest that these cause impaired type 4 collagen trafficking and endoplasmic reticulum stress. For protein-truncating variants, knockout models suggest that persistence of an immature α 1 α 1 α 2(IV) network is associated with biomechanical strain, which activates endothelin-A receptors leading to mesangial filopodia formation. Moreover, studies suggest that activation of collagen receptors, integrins and discoidin domain receptor 1, play a role in disease propagation. In this review, we provide an overview of how these genotype-phenotype mechanisms are key for a precision medicine-based approach in the future.

Excess dietary sodium restores electrolyte and water homeostasis caused by loss of the endoplasmic reticulum molecular chaperone, GRP170, in the mouse nephron

The maintenance of fluid and electrolyte homeostasis by the kidney requires proper folding and trafficking of ion channels and transporters in kidney epithelia. Each of these processes requires a specific subset of a diverse class of proteins termed molecular chaperones. One such chaperone is GRP170, which is an Hsp70-like, endoplasmic reticulum (ER)-localized chaperone that plays roles in protein quality control and protein folding in the ER. We previously determined that loss of GRP170 in the mouse nephron leads to hypovolemia, electrolyte imbalance, and rapid weight loss. In addition, GRP170-deficient mice develop an acute kidney injury (AKI)-like phenotype, typified by tubular injury, elevation of kidney injury markers, and induction of the unfolded protein response (UPR). By using an inducible GRP170 knockout cellular model, we confirmed that GRP170 depletion induces the UPR, triggers apoptosis, and disrupts protein homeostasis. Based on these data, we hypothesized that UPR induction underlies hyponatremia and volume depletion in these rodents and that these and other phenotypes might be rectified by sodium supplementation. To test this hypothesis, control and GRP170 tubule-specific knockout mice were provided a diet containing 8% sodium chloride. We discovered that sodium supplementation improved electrolyte imbalance and kidney injury markers in a sex-specific manner but was unable to restore weight or tubule integrity. These results are consistent with UPR induction contributing to the kidney injury phenotype in the nephron-specific GR170 knockout model and indicate that GRP170 function in kidney epithelia is essential to both maintain electrolyte balance and ER homeostasis.NEW & NOTEWORTHY Loss of the endoplasmic reticulum chaperone, GRP170, results in widespread kidney injury and induction of the unfolded protein response (UPR). We now show that sodium supplementation is able to at least partially restore electrolyte imbalance and reduce kidney injury markers in a sex-dependent manner.

The critical role of endoplasmic reticulum stress and the stimulator of interferon genes (STING) pathway in kidney fibrosis

Endoplasmic reticulum (ER) stress is a condition in which the ER is overwhelmed and unable to manage its protein load properly. The precise activation mechanisms and role of ER stress in kidney disease remain unclear. To study this, we performed unbiased transcriptomics analysis to demonstrate ER stress in kidneys of patients with chronic kidney disease and in mouse models of acute and chronic kidney injury (cisplatin and unilateral ureteral obstruction and reanalyzed previously published data on folic acid and mitochondrial transcription factor A(TFAM) knockout mice). Inhibiting the protein kinase RNA-like ER kinase (PERK) arm of ER stress but not activating transcription factor 6 or inositol-requiring enzyme 1, protected mice from kidney fibrosis. The stimulator of interferon genes (STING) was identified as an important upstream activator of ER stress in kidney tubule cells. STING and PERK were found to physically interact, and STING agonists induced PERK activation in kidney tubule cells. Mice with a STING activating mutation presented with ER stress and kidney fibroinflammation. We also generated mice with a tubule specific STING deletion that were resistant to ER stress and kidney fibrosis. Human kidney spatial transcriptomics highlighted a spatial correlation between STING, ER stress and fibrotic gene expression. Thus, our results indicate that STING is an important upstream regulator of PERK and ER stress in tubule cells during kidney fibrosis development.

Apelin-13 inhibits ischemia-reperfusion mediated podocyte apoptosis by reducing m-TOR phosphorylation to enhance autophagy

Podocytes are essential to maintain the normal filtration function of glomerular basement membrane, which could be injured by ischemia-reperfusion. As complicated function of autophagy in terminal differentiated podocytes, autophagy dysfunction might contribute to I/R induced renal dysfunction following glomerular filtration membrane (GFM) injuries. Meanwhile, apelin-13, an endogenous polypeptide, has been proved to be effective in regulating autophagy and apoptosis in podocytes. Therefore, it is hypothesized that apelin-13 may protect podocytes from IRI by inhibiting podocyte apoptosis through regulation of podocyte autophagy. Our study demonstrates for that podocytes are also involved in renal ischemia-reperfusion (I/R) injury and shows in detail the morphological and functional changes in podocytes during renal I/R. Because podocytes are terminally differentiated cells whose homeostasis require high levels of autophagy, we investigate the cellular mechanisms underlying the effects of apelin-13 on I/R-mediated podocyte injury in terms of autophagy. In addition, our study demonstrates that apelin-13 ameliorates renal I/R injury in podocyte injury, by increasing podocyte autophagy through inhibition of m-TOR phosphorylation, which in turn inhibits apoptosis.

Ginger-Derived Exosome-Like Nanoparticles Loaded With Indocyanine Green Enhances Phototherapy Efficacy for Breast Cancer

Purpose

Phototherapy has remarkable advantages in cancer treatment, owing to its high efficiency and minimal invasiveness. Indocyanine green (ICG) plays an important role in photo-mediated therapy. However, it has several disadvantages such as poor stability in aqueous solutions, easy aggregation of molecules, and short plasma half-life. This study aimed to develop an efficient nanoplatform to enhance the effects of photo-mediated therapy.

Methods

We developed a novel bio-nanoplatform by integrating edible ginger-derived exosome-like nanoparticles (GDNPs) and the photosensitizer, ICG (GDNPs@ICG). GDNPs were isolated from ginger juice and loaded with ICG by co-incubation. The size distribution, zeta potential, morphology, total lipid content, and drug release behavior of the GDNPs@ICG were characterized. The photothermal performance, cellular uptake and distribution, cytotoxicity, anti-tumor effects, and mechanism of action of GDNPs@ICG were investigated both in vitro and in vivo.

Results

GDNPs@ICG were taken up by tumor cells via a lipid-dependent pathway. When irradiated by an 808 nm NIR laser, GDNPs@ICG generated high levels of ROS, MDA, and local hyperthermia within the tumor, which caused lipid peroxidation and ER stress, thus enhancing the photo-mediated breast tumor therapy effect. Furthermore, in vivo studies demonstrated that engineered GDNPs@ICG significantly inhibited breast tumor growth and presented limited toxicity. Moreover, by detecting the expression of CD31, N-cadherin, IL-6, IFN-γ, CD8, p16, p21, and p53 in tumor tissues, we found that GDNPs@ICG substantially reduced angiogenesis, inhibited metastasis, activated the anti-tumor immune response, and promoted cell senescence in breast tumor.

Conclusion

Our study demonstrated that the novel bio-nanoplatform GDNPs@ICG enhanced the photo-mediated therapeutic effect in breast tumor. GDNPs@ICG could be an alternative for precise and efficient anti-tumor phototherapy.

The role of programmed cell death in organ dysfunction induced by opportunistic pathogens

Sepsis is a life-threatening condition resulting from pathogen infection and characterized by organ dysfunction. Programmed cell death (PCD) during sepsis has been associated with the development of multiple organ dysfunction syndrome (MODS), impacting various physiological systems including respiratory, cardiovascular, renal, neurological, hematological, hepatic, and intestinal systems. It is well-established that pathogen infections lead to immune dysregulation, which subsequently contributes to MODS in sepsis. However, recent evidence suggests that sepsis-related opportunistic pathogens can directly induce organ failure by promoting PCD in parenchymal cells of each affected organ. This study provides an overview of PCD in damaged organ and the induction of PCD in host parenchymal cells by opportunistic pathogens, proposing innovative strategies for preventing organ failure in sepsis.

Targeting endoplasmic reticulum stress: an innovative therapeutic strategy for podocyte-related kidney diseases

The endoplasmic reticulum (ER) is a vital organelle responsible for protein quality control, including the folding, modification, and transport of proteins. When misfolded or unfolded proteins accumulate in the ER, it triggers endoplasmic reticulum stress (ERS) and activates the unfolded protein response (UPR) to restore ER homeostasis. However, prolonged or excessive ERS can lead to apoptosis. The kidneys play a crucial role in maintaining physiological functions by excreting metabolic waste, regulating blood volume, balancing electrolytes and acid-base levels, and secreting various bioactive substances. Podocytes, epithelial cells situated outside the glomerular basement membrane, are essential for maintaining the structural integrity and permeability of the glomerular filtration barrier. Previous studies have shown that ERS in podocytes can contribute to the development of diseases such as glomerulonephritis, hereditary nephropathy, and diabetic kidney disease, potentially progressing to end-stage renal disease and causing patient mortality. As such, investigating ERS in podocytes has become a key area of focus in kidney disease research. This study examines recent advancements in understanding the effects of excessive ERS on podocytes across various kidney diseases, highlights the role of podocyte ERS in disease progression, and explores the potential therapeutic benefits of targeting the UPR to manage ERS in kidney diseases, thereby providing a scientific basis for clinical interventions.

Endoplasmic reticulum stress in the salivary glands of patients with primary Sjögren's syndrome, associated Sjögren's syndrome, and non-Sjögren's sicca syndrome: a comparative analysis and the influence of chloroquine

BACKGROUND

Endoplasmic reticulum stress (ERS) and the unfolded protein response (UPR) are adaptive mechanisms for conditions of high protein demand, marked by an accumulation of misfolded proteins in the endoplasmic reticulum (ER). Rheumatic autoimmune diseases (RAD) are known to be associated with chronic inflammation and an ERS state. However, the activation of UPR signaling pathways is not completely understood in Sjögren's disease (SD). This study evaluated the expression of ERS-related genes in glandular tissue of patients with primary SD (pSD), associated SD (aSD) with other autoimmune diseases, and non-Sjögren sicca syndrome (NSS).

METHODS

In a cross-sectional study, minor salivary gland biopsies were obtained from 44 patients with suspected SD and 13 healthy controls (HC). Patients were classified as pSD, aSD, or NSS based on clinical, serological, and histological assessment. Histopathological analysis and mRNA expression analysis of genes associated with ERS and UPR (PERK, XBP1, ATF-6, ATF-4, CANX, CALR, CHOP, and BIP) were performed on the samples. Differences between groups (pSD, aSD, NSS, and HC) were assessed. The influence of chloroquine (CQ) on the ER was also investigated.

RESULTS

Twenty-eight SD patients showed increased expression of PERK (p = 0.0117) and XBP1 (p = 0.0346), and reduced expression of ATF-6 (p = 0.0003) and CHOP (p = 0.0003), compared to the HC group. Increased expression of BIP (p < 0.0001), PERK (p = 0.0003), CALR (p < 0.0001), and CANX (p = 0.0111) was also observed in the SD group compared to the NSS group (n = 16). Patients receiving CQ (n = 16) showed a significant increase in ATF-6 (p = 0.0317) compared to patients not taking the medication (n = 29).

CONCLUSIONS

Altogether, the results suggest a greater activation of the ERS and UPR genes in patients with SD, especially in the pSD group. Antimalarial drugs, like CQ, used to treat RAD, may affect the ER function in exocrine glands.

Targeting endothelin signaling in podocyte injury and diabetic nephropathy-diabetic kidney disease

Despite advances in diabetes management, there is an urgent need for novel therapeutic strategies since the current treatments remain insufficient in halting the progression of diabetic nephropathy-diabetic kidney disease (DN-DKD). This review is mainly addressed on the pivotal role of endothelin-1 in the pathophysiology of DN, with a specific focus on its effects on podocytes and the glomerular filtration barrier. Endothelin-1 promotes mesangial cell proliferation, sclerosis, and direct podocyte injury via the activation of endothelin type A and B receptors, that drive the progression of glomerulosclerosis in DN-DKD. Endothelin receptor antagonists, including drugs like atrasentan and sparsentan, have demonstrated nephroprotective effects in experimental models by reducing proteinuria and podocyte injury. The therapeutic potential to slow the progression of DN to end-stage kidney disease (ESKD) of these endothelin receptor antagonists in clinical practice is currently under evaluation. However, fluid retention and increased risk of heart failure associated with endothelin receptor antagonists need careful consideration. This review aims to provide an in-depth analysis of the pathophysiological role of endothelin and the emerging therapeutic implications of targeting this pathway in DN-DKD and discusses efficacy, safety, and the possibility of combining the new generation of endothelin receptor antagonists with the standard treatment of CKD and DN-DKD.

Novel Insights from Comprehensive Bioinformatics Analysis Utilizing Large-Scale Human Transcriptomes and Experimental Validation: The Role of Autophagy in Periodontitis

Objective

Autophagy plays a crucial role in the pathophysiology of periodontitis, yet its precise involvement in the disease process remains elusive. The aim of the present study was thus to investigate the involvement of autophagy in the pathology of periodontitis. This investigation involved transcriptomic analysis of a broad range of human samples and complemented by in vitro experimentation.

Materials and Methods

We analyzed the transcriptomes of human gingival tissues from individuals with periodontitis and health controls to identify the differential expression of autophagy-related genes (DEARGs) and to investigate their potential interactions and functional pathways. Additionally, protein-protein interaction (PPI) networks were constructed to identify key functional modules and hub genes. Experimental validation of autophagy regulation in periodontitis and identification of key autophagy-regulating genes was accomplished through in vitro cellular experiments. Subsequently, a comprehensive analysis of immune cell infiltrate utilizing the CIBERSORT algorithm was performed. Finally, leveraging the DSigDB database, potential candidate drugs for periodontitis treatment targeting autophagy were predicted.

Results

A total of 79 genes have been identified as DEARGs in periodontitis. An intricate interplay among the DEARGs and their impact on the regulatory mechanisms of autophagy within the context of periodontitis was observed. Subsequently, 10 hub genes were discerned through the establishment of a PPI network. Furthermore, dysregulated autophagic activity in periodontitis was validated, and 9 key genes (APP, KDR, IL1B, CXCL12, CXCR4, IL6, FOS, LCK, and SHC1) were identified through in vitro experiments. Our analysis unveiled an association between these genes and altered immune cell infiltration in periodontitis. Additionally, we predicted potential therapeutic agents such as curcumin, 27-hydroxycholesterol, and Trolox, showing promise in the treatment of periodontitis by modulating the autophagic process.

Conclusion

This study identified nine key genes for autophagy regulation and potential therapeutic agents in periodontitis. These findings not only enhance our comprehension of the pathological mechanisms of periodontitis but also provide substantial evidence for the advancement of novel therapeutic strategies.

The pro-fibrotic role of autophagy in renal intrinsic cells: mechanisms and therapeutic potential in chronic kidney disease

Chronic kidney disease (CKD) represents a significant global public health burden, affecting over 10% of the world's population. Its high morbidity, multifactorial complications, and substantial mortality impose significant burdens on healthcare systems and patients, necessitating considerable investment in healthcare resources. Renal fibrosis (RF) is a key pathological feature and driver of CKD progression. Extensive research indicates that autophagy participates in the complete pathogenesis of RF. Under physiological conditions, autophagy is essential for maintaining renal cellular homeostasis. However, under pathological conditions, perhaps aberrant and sustained activation of autophagy contributes to oxidative stress, apoptosis, inflammation, etc. Ultimately, they accelerate the development of RF. The role of autophagy in RF is currently controversial. This review investigates the molecular mechanisms by which intrinsic renal cell autophagy contributes to RF across diverse disease models, suggesting that autophagy and its associated regulatory pathways represent potential diagnostic and therapeutic targets for CKD.

Research progress and advances in endoplasmic reticulum stress regulation of acute kidney injury

Acute kidney injury (AKI) is a common and severe clinical disorder in which endoplasmic reticulum (ER) stress plays an important regulatory role. In this review, we summarize the research progress on the relationship between ER stress and AKI. It emphasizes the importance of maintaining a balance between promoting and protecting ER stress during AKI and highlights the potential of ER stress-targeted drugs as a new therapeutic approach for AKI. The article also discusses the need for developing drugs that target ER stress effectively while avoiding adverse effects on normal cells and tissues. The review concludes that with a more comprehensive understanding of ER stress mechanisms and advancements in research techniques, more effective treatment options for AKI can be developed in the future.

Natural products derived from traditional Chinese medicines targeting ER stress for the treatment of kidney diseases

Various factors, both internal and external, can disrupt endoplasmic reticulum (ER) homeostasis and increase the burden of protein folding, resulting in ER stress. While short periods of ER stress can help cells return to normal function, excessive or prolonged ER stress triggers a complex signaling network that negatively affects cells. Numerous studies have demonstrated the significant role of ER stress in various kidney diseases, such as immune-related kidney injury, diabetic kidney diseases, renal ischemia reperfusion injury, and renal fibrosis. To date, there is a severe shortage of medications for the treatment of acute and chronic kidney diseases of all causes. Natural products derived from various traditional Chinese medicines (TCM), which are a major source of new drugs, have garnered considerable attention. Recent research has revealed that many natural products have renoprotective effects by targeting ER stress-mediated events, such as apoptosis, oxidative stress, inflammation, autophagy, and epithelial-mesenchymal transition. This article provides a comprehensive review of the current research progress on natural products targeting ER stress for the treatment of kidney diseases.

Inhibition of SGLT2 protects podocytes in diabetic kidney disease by rebalancing mitochondria-associated endoplasmic reticulum membranes

BACKGROUND

Sodium-glucose cotransporter 2 (SGLT2) inhibitors have changed the therapeutic landscape for diabetic kidney disease (DKD) patients, but their underlying mechanisms are complicated and not fully understood. Mitochondria-associated endoplasmic reticulum membranes (MAMs), the dynamic contact sites between mitochondria and the endoplasmic reticulum (ER), serve as intracellular platforms important for regulating cellular fate and function. This study explored the roles and mechanisms of SGLT2 inhibitors in regulating MAMs formation in diabetic podocytes.

METHODS

We assessed MAMs formation in podocytes from DKD patients' renal biopsy samples and induced an increase in MAMs formation in cultured human podocytes by transfecting OMM-ER linker plasmid to investigate the effects of MAMs imbalance on podocyte injury. Empagliflozin-treated diabetic mice and podocyte-specific SGLT2 knockout diabetic mice (diabetic states were induced by streptozotocin and a high-fat diet), empagliflozin-treated podocytes, SGLT2-downregulated podocytes, and SGLT2-overexpressing podocytes were used to investigate the effects and mechanisms of SGLT2 inhibitors on MAMs formation in diabetic podocytes.

RESULTS

MAMs were increased in podocytes and were associated with renal dysfunction in DKD patients. Increased MAMs aggravated HG-induced podocyte injury. The expression of SGLT2 was increased in diabetic podocytes. In addition, empagliflozin-treatment and podocyte-specific SGLT2 knockout attenuated MAMs formation and podocyte injury in diabetic mice. Empagliflozin treatment and SGLT2 knockdown decreased podocyte MAMs formation by activating the AMP-activated protein kinase (AMPK) pathway, while SGLT2 overexpression had the opposite effect.

CONCLUSIONS

Inhibition of SGLT2 attenuates MAMs imbalance in diabetic podocytes by activating the AMPK pathway. This study expands our knowledge of the roles of SGLT2 inhibitors in improving DKD podocyte injury and provides new insights into DKD treatment.

Micro/nano plastics in the urinary system: Pathways, mechanisms, and health risks

Micro/Nano plastics (MNPs) pollutants are widespread in the environment, raising significant concerns about their biosafety. Emerging studies indicate that the urinary system is a primary accumulation site for MNPs, leading to severe tissue and functional damage. This review aims to summarize recent research on the potential hazards that MNPs may pose to the urinary system, highlighting the mechanisms of toxicity and the current state of knowledge. Studies have shown that MNPs enter the human body through drinking water, the food chain, inhalation, and skin contact. They may penetrate the bloodstream via the digestive, respiratory, and skin systems, subsequently dispersing to various organs, including the urinary system. The potential accumulation of MNPs in the urinary system might induce cellular oxidative stress, inflammation, apoptosis, autophagy, the "intestine-kidney axis", and other possible toxic mechanisms. These processes could disrupt kidney metabolic functions and promote tissue fibrosis, thereby potentially increasing the risk of urinary system diseases. Despite ongoing research, the understanding of MNPs' impact on the urinary system remains limited. Therefore, this review provides a comprehensive overview of MNPs' potential toxicity mechanisms in the urinary system, highlights key challenges, and outlines future research directions. It offers a theoretical basis for the development of effective protective measures and policies.

H2S alleviated sepsis-induced acute kidney injury by inhibiting PERK/Bax-Bcl2 pathway

To investigate the protective mechanisms of hydrogen sulfide (H2S) in sepsis-induced acute kidney injury (SAKI), we conducted an in vivo study using a SAKI mouse model induced by intraperitoneal lipopolysaccharide (LPS) injection. Following 6 h of LPS injection, levels of tumor necrosis factor-alpha (TNF-α) and blood urea nitrogen (Bun) were significantly elevated in mouse plasma. In the kidneys of SAKI mice, expression of H2S-generating enzymes cysteinyl-tRNA synthetase (CARS), cystathionine γ-lyase (CSE) and cystathionine β-synthase (CBS) was markedly downregulated, while glucose-regulated protein 78 (GRP78), activating transcription factor 6 (ATF6), phosphorylated protein kinase R-like endoplasmic reticulum kinase/protein kinase R-like endoplasmic reticulum kinase (p-PERK/PERK), and B-cell lymphoma-2 recombinant protein X/B-cell lymphoma-2 (Bax/Bcl2) expression was significantly upregulated. H2S improved renal function and attenuated renal histopathological changes in SAKI mice, thereby alleviating LPS-induced endoplasmic reticulum stress (ERS). Additionally, it inhibited the expression of p-PERK/PERK and Bax/Bcl2. After inhibiting CSE activity with dl-propargylglycine (PPG i. p.), the renal tissue pathology in LPS-induced AKI mice was further exacerbated, leading to enhanced activation of the PERK/Bax-Bcl2 pathway. Our findings suggest that endogenous H2S influences the pathogenesis of SAKI, while exogenous H2S protects against LPS-induced AKI by inhibiting the PERK/Bax-Bcl2 pathway involved in ERS.

Targeting endoplasmic reticulum stress-induced lymphatic dysfunction for mitigating bisphosphonate-related osteonecrosis

BACKGROUND

Bisphosphonates (BPs) are the first-line treatment to stop bone resorption in diseases, including osteoporosis, Paget's disease, multiple myeloma and bone metastases of cancer. However, BPs-related osteonecrosis of the jaw (BRONJ), characterized by local inflammation and jawbone necrosis, is a severe intractable complication. The cumulative inflammatory burden often accompanies impaired lymphatic drainage, but its specific impact on BRONJ and the underlying mechanisms remain unclear.

METHODS

The mouse BRONJ model was established to assess the integrity and drainage function of lymphatic vessels by tissue clearing techniques, injected indocyanine green lymphatic clearance assay, flow cytometry analysis and histopathological staining. RNA sequencing, metabolome analysis, transmission electron microscopy and Western blotting were utilized to analyze the impacts of Zoledronate acid (ZA) on endoplasmic reticulum stress (ERS) and function of lymphatic endothelial cells (LECs). By constructing Lyve1creERT; SIRT6f/f and Lyve1creERT; ATG5f/f mice, we evaluated the role of ERS-induced LECs apoptosis in the progression of BRONJ. Additionally, we developed a nanoparticle-loaded ZA and rapamycin (ZDPR) to enhance autophagy and evaluated its potential in mitigating BRONJ.

RESULTS

The mouse BRONJ model displayed impaired lymphatic drainage, accompanied by significant local inflammation and bone necrosis. The prolonged stimulation of ZA resulted in the extension of ERS and the inhibition of autophagy in LECs, ultimately leading to apoptosis. Mechanistically, ZA activated XBP1s through the NAD+/SIRT6 pathway, initiating ERS-induced apoptosis in LECs. The conditional knockout mouse models demonstrated that the deletion of SIRT6 or ATG5 significantly worsened lymphatic drainage and inflammatory infiltration in BRONJ. Additionally, the innovative nanoparticle ZDPR alleviated ERS-apoptosis in LECs and enhanced lymphatic function, facilitating inflammation resolution.

CONCLUSION

Our study has elucidated the role of the NAD+/SIRT6/XBP1s pathway in ERS-induced apoptosis in ZA-treated LECs, and further confirmed the therapeutic potential of ZDPR in restoring endothelial function and improving lymphatic drainage, thereby effectively mitigating BRONJ.

KEY POINTS

Bisphosphonate-induced lymphatic drainage impairment exacerbates bone necrosis. Zoledronate acid triggers endoplasmic reticulum stress and apoptosis in lymphatic endothelial cells via the NAD+/SIRT6/XBP1s pathway. Novel nanoparticle-loaded Zoledronate acid and rapamycin enhances autophagy, restores lymphatic function, and mitigates bisphosphonates-related osteonecrosis of the jaw progression.

Genetic deletion of calcium-independent phospholipase A2γ protects mice from diabetic nephropathy

Calcium-independent phospholipase A2γ (iPLA2γ) is localized in glomerular epithelial cells (GECs)/podocytes at the mitochondria and endoplasmic reticulum, and can mediate release of arachidonic acid and prostanoids. Global knockout (KO) of iPLA2γ in mice did not cause albuminuria, but resulted in mitochondrial structural abnormalities and enhanced autophagy in podocytes. In acute glomerulonephritis, deletion of iPLA2γ exacerbated albuminuria and podocyte injury. This study addresses the role of iPLA2γ in diabetic nephropathy. Hyperglycemia was induced in male mice with streptozotocin (STZ). STZ induced progressive albuminuria in control mice (over 21 weeks), while albuminuria did not increase in iPLA2γ KO mice, remaining comparable to untreated groups. Despite similar exposure to STZ, the STZ-treated iPLA2γ KO mice developed a lower level of hyperglycemia compared to STZ-treated control. However, there was no significant correlation between the degree of hyperglycemia and albuminuria, and even iPLA2γ KO mice with greatest hyperglycemia did not develop significant albuminuria. Mortality at 21 weeks was greatest in diabetic control mice. Sclerotic glomeruli and enlarged glomerular capillary loops were increased significantly in diabetic control compared to diabetic iPLA2γ KO mice. Glomerular matrix was expanded in diabetic mice, with control exceeding iPLA2γ KO. Glomerular autophagy (increased LC3-II and decreased p62) was enhanced in diabetic iPLA2γ KO mice compared to control. Treatment of cultured GECs with H2O2 resulted in increased cell death in control GECs compared to iPLA2γ KO, and the increase was slightly greater in medium with high glucose compared to low glucose. H2O2-induced cell death was not affected by inhibition of prostanoid production with indomethacin. In conclusion, mice with global deletion of iPLA2γ are protected from developing chronic glomerular injury in diabetic nephropathy. This is associated with increased glomerular autophagy.

Quantitative proteomics reveals the mechanism of endoplasmic reticulum stress-mediated pulmonary fibrosis in mice

Pulmonary fibrosis is a progressive disease that can lead to respiratory failure. Many types of cells are involved in the progression of pulmonary fibrosis. This study utilized quantitative proteomics to investigate the mechanism of TGF-β-induced fibrosis-like changes in mouse epithelial cells. Our findings revealed that TGF-β significantly impacted biological processes related to the endoplasmic reticulum, mitochondrion, and ribonucleoprotein complex. Pull-down assay coupled with proteomics identified 114 proteins that may directly interact with TGF-β, and their functions were related to mitochondria, translation, ubiquitin ligase conjugation, mRNA processing, and actin binding. Among them, 17 molecules were also found in different expression proteins (DEPs) of quantitative proteomic, such as H1F0, MED21, SDF2L1, DAD1, and TMX1. Additionally, TGF-β decreased the folded structure and the number of ribosomes in the endoplasmic reticulum and increased the expression of key proteins in the unfolded protein response, including HRD1, PERK, and ERN1. Overall, our study suggested that TGF-β induced fibrotic changes in mouse lung epithelial cells by ER stress and initiated the unfolded protein response through the PRKCSH/IRE1 and PERK/GADD34/CHOP signaling pathways.

Protective effect of magnetic water against AlCl3-induced hepatotoxicity in rats

This study aimed to examine whether or not aluminum chloride (AlCl3)-induced hepatotoxicity might be mitigated using magnetic water (MW) in rats. This study involved 28 adult male rats randomly assigned into the following 4 groups (7 rats/group): normal control (Cnt), MW, AlCl3, and Al Cl3 + MW. The Cnt group orally received normal saline, the MW group drank MW ad libitum for 2 months, and the AlCl3 and AlCl3 + MW groups were orally administered AlCl3 (40 mg/kg b.w.) alone or in combination with MW for 2 months, respectively. MW reduced AlCl3 toxicity as proved at functional, molecular, and structural levels. Functionally, MW reduced serum levels of liver enzymes (ALT, AST, ALP, GGT), while increased total proteins, and albumin. MW also restored redox balance in the liver (lower MDA levels, higher activities of CAT and SOD enzymes, and upregulated expression of NrF2, HO-1, and GST genes. Molecularly, MW downregulated hepatic expression of the epigenetic (HDAC3), inflammatory (IL1β, TNFα, NFκβ), and endoplasmic reticulum stress (XBP1, BIP, CHOP) genes. Structurally, MW enhanced liver histology. With these results, we could conclude that MW has the potential to ameliorate the hepatotoxic effects of AlCl3 through targeting oxidative stress, inflammation, epigenesis, and endoplasmic reticulum stress.

Research Progress on the Mechanism for Improving Glucose and Lipid Metabolism Disorders Using Phenolic Acid Components from Medicinal and Edible Homologous Plants

Glucose and lipid metabolism disorders are the core pathological mechanism of a variety of metabolic diseases, and the incidence of related diseases is increasing year by year, which seriously threatens human life and health. Traditional Chinese medicine with medicinal and edible properties refers to Chinese medicinal resources that have both medicinal and edible characteristics. Due to its safety and its health-promoting and medicinal functions, traditional Chinese medicine has received increasing attention in the development of functional health foods. Phenolic acids are important secondary metabolites that are ubiquitous in medicinal and edible homologous plants, and the regulation of glycolipid metabolism is an important activity and plays a key role in many diseases. In this paper, we focus on the alleviation of glycolipid disorders using MEHH phenolic acids, which regulate glucose metabolism and lipid metabolism, improve insulin resistance, inhibit inflammatory responses, alleviate oxidative stress, and regulate intestinal flora; additionally, we summarize the mechanism in order to provide a reference for MEHH phenolic acids in the treatment of glycolipid metabolism diseases.

Nogo-B Promotes Endoplasmic Reticulum Stress-Mediated Autophagy in Endothelial Cells of Diabetic Nephropathy

Aims: Endothelial cells are the critical targets of injury in diabetic nephropathy (DN), and endothelial cell lesions contribute to the disease progression. Neurite outgrowth inhibitor B (Nogo-B), an endoplasmic reticulum (ER)-resident protein, plays a pivotal role in vascular remodeling after injury, and maintains the structure and function of the ER. Yet, the role of Nogo-B in the regulation of ER stress and endothelial cell injury remains largely unknown. Herein, we tested the hypothesis that Nogo-B activates ER stress-mediated autophagy and protects endothelial cells in DN. Results: The level of Nogo-B was decreased in glomerular endothelial cells in biopsy specimens from DN patients. In vivo and in vitro studies have shown that silencing Nogo-B activated ER stress signaling, and affected the expression of autophagy-related marker early growth response 1 and microtubule-associated protein light chain 3 (LC3) in endothelial cells in hyperglycemic condition. Conclusion and Innovation: These results denote that Nogo-B contributes to ER stress-mediated autophagy and protects endothelial cells in DN, providing new evidence for understanding the role of ER stress-mediated autophagy in endothelial cells of DN.

Endoplasmic reticulum stress promotes oxidative stress, inflammation, and apoptosis: A novel mechanism of citrinin-induced renal injury and dysfunction

Citrinin (CTN) has been reported to induce renal failure and structural damage, but its nephrotoxic effects and mechanisms are not fully understood. Therefore, we established a model by orally administering CTN (0, 1.25, 5, or 20 mg/kg) to mice for 21 consecutive days. Histological and biochemical analyses revealed that CTN caused structural damage to renal tubules, increased inflammatory cell infiltration, and elevated levels of serum markers of renal function (creatinine, urea, and uric acid). Moreover, mRNA transcript levels of the inflammatory factors TNF-α, IL-1β, and IL-6 were increased, indicating the occurrence of an inflammatory response. Furthermore, exposure to CTN induced renal oxidative stress by decreasing antioxidant GSH levels, antioxidant enzyme (SOD, CAT) activities, and increasing oxidative products (ROS, MDA). In addition, CTN increased the expression of proteins associated with endoplasmic reticulum (ER)stress and apoptotic pathways. ER stress has been shown to be involved in regulating various models of kidney disease, but its role in CTN-induced renal injury has not been reported. We found that pretreatment with the ER stress inhibitor 4-PBA (240 mg/kg, ip) alleviated CTN-induced oxidative stress, NF-κB pathway mediated inflammatory response, and apoptosis. Interestingly, 4-PBA also partially alleviated renal structural damage and dysfunction. Thus, ER stress may be a novel target for the prevention and treatment of CTN-induced renal injury.

Radix Astragali and Its Representative Extracts for Diabetic Nephropathy: Efficacy and Molecular Mechanism

Diabetic nephropathy (DN) is a common microvascular complication of diabetes mellitus (DM). Radix Astragali (RA), a frequently used Chinese herbal medicine in the Leguminosae family, Astragalus genus, with its extracts, has been proven to be effective in DN treatment both in clinical practice and experimental studies. RA and its extracts can reduce proteinuria and improve renal function. They can improve histopathology changes including thickening of the glomerular basement membrane, mesangial cell proliferation, and injury of endothelial cells, podocytes, and renal tubule cells. The mechanisms mainly benefited from antioxidative stress which involves Nrf2/ARE signaling and the PPARγ-Klotho-FoxO1 axis; antiendoplasmic reticulum stress which involves PERK-ATF4-CHOP, PERK/eIF2α, and IRE1/XBP1 pathways; regulating autophagy which involves SIRT1/NF-κB signaling and AMPK signaling; anti-inflammation which involves IL33/ST2 and NF-κB signaling; and antifibrosis which involves TGF-β1/Smads, MAPK (ERK), p38/MAPK, JNK/MAPK, Wnt/β-catenin, and PI3K/AKT/mTOR signaling pathways. This review focuses on the clinical efficacy and the pharmacological mechanism of RA and its representative extracts on DN, and we further document the traditional uses of RA and probe into the TCM theoretical basis for its application in DN.

Characterization of the Bax Inhibitor-1 Family in Cauliflower and Functional Analysis of BobBIL4

The Bax inhibitor-1 (BI-1) gene family, which is important for plant growth, development, and stress tolerance, remains largely unexplored in cauliflower. In this study, we identified and characterized cauliflower BI-1 family genes. Based on aligned homologous sequences and collinearity with Arabidopsis genes, we identified nine cauliflower BI-1 genes, which encode proteins that varied in length, molecular weight, isoelectric point, and predicted subcellular localization, including the Golgi apparatus, plasma membrane, and various compartments within the chloroplast. Phylogenetic analyses detected evolutionary conservation and divergence among these genes. Ten structural motifs were identified, with Motif 5 found to be crucial for inhibiting apoptosis. According to the cis-regulatory elements in their promoters, these genes likely influence hormone signaling and stress responses. Expression profiles among tissues highlighted the functional diversity of these genes, with particularly high expression levels observed in the silique and root. Focusing on BobBIL4, we investigated its role in brassinosteroid (BR)-mediated root development and salt stress tolerance. BobBIL4 expression levels increased in response to BR and salt treatments. The functional characterization of this gene in Arabidopsis revealed that it enhances root growth and salinity tolerance. These findings provide insights into BI-1 gene functions in cauliflower while also highlighting the potential utility of BobBIL4 for improving crop stress resistance.

The roles and mechanisms of endoplasmic reticulum stress-mediated autophagy in animal viral infections

The endoplasmic reticulum (ER) is a unique organelle responsible for protein synthesis and processing, lipid synthesis in eukaryotic cells, and the replication of many animal viruses is closely related to ER. A considerable number of viral proteins are synthesised during viral infection, resulting in the accumulation of unfolded and misfolded proteins in ER, which in turn induces endoplasmic reticulum stress (ERS). ERS further drives three signalling pathways (PERK, IRE1, and ATF6) of the cellular unfolded protein response (UPR) to respond to the ERS. In numerous studies, ERS has been shown to mediate autophagy, a highly conserved cellular degradation mechanism to maintain cellular homeostasis in eukaryotic cells, through the UPR to restore ER homeostasis. ERS-mediated autophagy is closely linked to the occurrence and development of numerous viral diseases in animals. Host cells can inhibit viral replication by regulating ERS-mediated autophagy, restoring the ER's normal physiological process. Conversely, many viruses have evolved strategies to exploit ERS-mediated autophagy to achieve immune escape. These strategies include the regulation of PERK-eIF2α-Beclin1, PERK-eIF2α-ATF4-ATG12, IRE1α-JNK-Beclin1, and other signalling pathways, which provide favourable conditions for the replication of animal viruses in host cells. The ERS-mediated autophagy pathway has become a hot topic in animal virological research. This article reviews the most recent research regarding the regulatory functions of ERS-mediated autophagy pathways in animal viral infections, emphasising the underlying mechanisms in the context of different viral infections. Furthermore, it considers the future direction and challenges in the development of ERS-mediated autophagy targeting strategies for combating animal viral diseases, which will contribute to unveiling their pathogenic mechanism from a new perspective and provide a scientific reference for the discovery and development of new antiviral drugs and preventive strategies.

Mito-LND and (E)-Akt inhibitor-IV: novel compounds inducing endoplasmic reticulum stress and ROS accumulation against hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related mortality. Although multi-kinase inhibitors can prolong the overall survival of late-stage HCC patients, the emergence of drug resistance diminishes these benefits, ultimately resulting in treatment failure. Therefore, there is an urgent need for novel and effective drugs to impede the progression of liver cancer.

METHODS

This study employed a concentration gradient increment method to establish acquired sorafenib or regorafenib-resistant SNU-449 cells. Cell viability was assessed using the cell counting kit-8 assay. A library of 793 bioactive small molecules related to metabolism screened compounds targeting both parental and drug-resistant cells. The screened compounds will be added to both the HCC parental cells and the drug-resistant cells, followed by a comprehensive assessment. Intracellular adenosine triphosphate (ATP) levels were quantified using kits. Flow cytometry was applied to assess cell apoptosis and reactive oxygen species (ROS). Real-time quantitative PCR studied relative gene expression, and western blot analysis assessed protein expression changes in HCC parental and drug-resistant cells. A xenograft model in vivo evaluated Mito-LND and (E)-Akt inhibitor-IV effects on liver tumors, with hematoxylin and eosin staining for tissue structure and immunohistochemistry staining for endoplasmic reticulum stress protein expression.

RESULTS

From the compound library, we screened out two novel compounds, Mito-LND and (E)-Akt inhibitor-IV, which could potently kill both parental cells and drug-resistant cells. Mito-LND could significantly suppress proliferation and induce apoptosis in HCC parental and drug-resistant cells by upregulating glycolytic intermediates and downregulating those of the tricarboxylic acid (TCA) cycle, thereby decreasing ATP production and increasing ROS. (E)-Akt inhibitor-IV achieved comparable results by reducing glycolytic intermediates, increasing TCA cycle intermediates, and decreasing ATP synthesis and ROS levels. Both compounds trigger apoptosis in HCC cells through the interplay of the AMPK/MAPK pathway and the endoplasmic reticulum stress response. In vivo assays also showed that these two compounds could significantly inhibit the growth of HCC cells and induce endoplasmic reticulum stress.

CONCLUSION

Through high throughput screening, we identified that Mito-LND and (E)-Akt inhibitor-IV are two novel compounds against both parental and drug-resistant HCC cells, which could offer new strategies for HCC patients.

Mitigation of ROS-triggered endoplasmic reticulum stress by upregulating Nrf2 retards diabetic nephropathy

Endoplasmic reticulum stress (ERS) plays a crucial role in the pathogenesis of diabetic nephropathy (DN), and it is often accompanied by an increase in reactive oxygen species (ROS) production. However, the precise relationship between NFE2-related factor-2 (Nrf2), a key regulator of ROS balance, and ERS in DN remains elusive. This study aimed to investigate the impact of Nrf2 on ERS and its therapeutic potential in DN. Herein, ERS-related changes, including increased activating transcription factor-6 (ATF6), glucose-regulated protein 78 (GRP78), and transcription factor C/EBP homologous protein (CHOP) expression, were observed in the renal tissues of streptozotocin-induced DN mice and high glucose cultured human renal proximal tubular (HK-2) cells. Nrf2 knockdown increased the sensitivity of HK-2 cells to ERS under high glucose conditions, underscoring the regulatory role of Nrf2 in ERS modulation. Notably, upregulating Nrf2 in ezetimibe-treated diabetic mice restored ERS markers and ameliorated albuminuria, glomerular hypertrophy, mesangial expansion, and tubulointerstitial fibrosis. Furthermore, the inhibition of ERS in HK-2 cells by the ROS scavenger, N-acetylcysteine, highlights the interplay between ROS and ERS. This study, for the first time, elucidates that the upregulation of Nrf2 may alleviate the negative influence of ROS-mediated ERS, presenting a promising therapeutic avenue for delaying the progression of DN. These findings suggest a potential strategy for targeting Nrf2 and ERS in developing novel therapeutic interventions for DN.

Podocyte Death in Diabetic Kidney Disease: Potential Molecular Mechanisms and Therapeutic Targets

Cell deaths maintain the normal function of tissues and organs. In pathological conditions, the abnormal activation or disruption of cell death often leads to pathophysiological effects. Diabetic kidney disease (DKD), a significant microvascular complication of diabetes, is linked to high mortality and morbidity rates, imposing a substantial burden on global healthcare systems and economies. Loss and detachment of podocytes are key pathological changes in the progression of DKD. This review explores the potential mechanisms of apoptosis, necrosis, autophagy, pyroptosis, ferroptosis, cuproptosis, and podoptosis in podocytes, focusing on how different cell death modes contribute to the progression of DKD. It recognizes the limitations of current research and presents the latest basic and clinical research studies targeting podocyte death pathways in DKD. Lastly, it focuses on the future of targeting podocyte cell death to treat DKD, with the intention of inspiring further research and the development of therapeutic strategies.

The interaction of ER stress and autophagy in trophoblasts: navigating pregnancy outcome†

The endoplasmic reticulum is a complex and dynamic organelle that initiates unfolded protein response and endoplasmic reticulum stress in response to the accumulation of unfolded or misfolded proteins within its lumen. Autophagy is a paramount intracellular degradation system that facilitates the transportation of proteins, cytoplasmic components, and organelles to lysosomes for degradation and recycling. Preeclampsia and intrauterine growth retardation are two common complications of pregnancy associated with abnormal trophoblast differentiation and placental dysfunctions and have a major impact on fetal development and maternal health. The intricate interplay between endoplasmic reticulum stress, and autophagy and their impact on pregnancy outcomes, through mediating trophoblast differentiation and placental development, has been highlighted in various reports. Autophagy controls trophoblast regulation through a variety of gene expressions and signaling pathways while excessive endoplasmic reticulum stress triggers downstream apoptotic signaling, culminating in trophoblast apoptosis. This comprehensive review delves into the intricacies of placental development and explores the underlying mechanisms of preeclampsia and intrauterine growth retardation. In addition, this review will elucidate the molecular mechanisms of endoplasmic reticulum stress and autophagy, both individually and in their interplay, in mediating placental development and trophoblast differentiation, particularly highlighting their roles in preeclampsia and intrauterine growth retardation development. This research seeks to the interplay between endoplasmic reticulum stress and impaired autophagy in the placental trophoderm, offering novel insights into their contribution to pregnancy complications.

The pivotal role of dysregulated autophagy in the progression of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is a clinicopathologic syndrome characterized by excessive fat deposition in hepatocytes and a major cause of end-stage liver disease. Autophagy is a metabolic pathway responsible for degrading cytoplasmic products and damaged organelles, playing a pivotal role in maintaining the homeostasis and functionality of hepatocytes. Recent studies have shown that pharmacological intervention to activate or restore autophagy provides benefits for liver function recovery by promoting the clearance of lipid droplets (LDs) in hepatocytes, decreasing the production of pro-inflammatory factors, and inhibiting activated hepatic stellate cells (HSCs), thus improving liver fibrosis and slowing down the progression of NAFLD. This article summarizes the physiological process of autophagy, elucidates the close relationship between NAFLD and autophagy, and discusses the effects of drugs on autophagy and signaling pathways from the perspectives of hepatocytes, kupffer cells (KCs), and HSCs to provide assistance in the clinical management of NAFLD.

PTEN in kidney diseases: a potential therapeutic target in preventing AKI-to-CKD transition

Renal fibrosis, a critical factor in the development of chronic kidney disease (CKD), is predominantly initiated by acute kidney injury (AKI) and subsequent maladaptive repair resulting from pharmacological or pathological stimuli. Phosphatase and tensin homolog (PTEN), also known as phosphatase and tensin-associated phosphatase, plays a pivotal role in regulating the physiological behavior of renal tubular epithelial cells, glomeruli, and renal interstitial cells, thereby preserving the homeostasis of renal structure and function. It significantly impacts cell proliferation, apoptosis, fibrosis, and mitochondrial energy metabolism during AKI-to-CKD transition. Despite gradual elucidation of PTEN's involvement in various kidney injuries, its specific role in AKI and maladaptive repair after injury remains unclear. This review endeavors to delineate the multifaceted role of PTEN in renal pathology during AKI and CKD progression along with its underlying mechanisms, emphasizing its influence on oxidative stress, autophagy, non-coding RNA-mediated recruitment and activation of immune cells as well as renal fibrosis. Furthermore, we summarize prospective therapeutic targeting strategies for AKI and CKD-treatment related diseases through modulation of PTEN.

Effects of ginsenoside Rh2 on cisplatin-induced nephrotoxicity in renal tubular epithelial cells by inhibiting endoplasmic reticulum stress

Nephrotoxicity remains a major adverse reaction of the anticancer drug cisplatin (CDDP) chemotherapy, which is an important risk factor for chronic renal disease. Ginsenoside Rh2 from Panax ginseng has been shown to protect against CDDP-induced nephrotoxicity in vivo, but its pharmacological effect on renal tubular epithelial cells is not clearly understood. This study examined the molecular mechanisms underlying the nephroprotective effects of Rh2 on CDDP-induced HK-2 cells and acute kidney injury (AKI) mice. As a result of Rh2 treatment, CDDP-induced HK-2 cells showed increased cell viability and reduced lactate dehydrogenase release. Moreover, Rh2 ameliorated CDDP-induced mitochondrial membrane potential, increased antioxidant enzyme activities, and reduced pro-inflammatory cytokine expression to reduce damage. Rh2 inhibited apoptosis and enhanced the antioxidant capacity of HK-2 cells by reducing proteins associated with endoplasmic reticulum (ER) stress, as well as by attenuating tunicamycin-induced ER stress. In addition, treatment of CDDP-induced AKI mice with Rh2 substantially reduced blood urea nitrogen and serum creatinine levels, attenuated histological damage of kidney. Further, Rh2 also improved kidney function by inhibiting ER stress to support in vitro findings. These results consistently demonstrated that Rh2 protects renal tubular epithelial cells from CDDP-induced nephrotoxicity and apoptosis by restoring ER homeostasis, which might suggest a therapeutic potential and providing new insights into AKI alternative therapies.

The role of glucagon-like peptide-1/GLP-1R and autophagy in diabetic cardiovascular disease

Diabetes leads to a significantly accelerated incidence of various related macrovascular complications, including peripheral vascular disease and cardiovascular disease (the most common cause of mortality in diabetes), as well as microvascular complications such as kidney disease and retinopathy. Endothelial dysfunction is the main pathogenic event of diabetes-related vascular disease at the earliest stage of vascular injury. Understanding the molecular processes involved in the development of diabetes and its debilitating vascular complications might bring up more effective and specific clinical therapies. Long-acting glucagon-like peptide (GLP)-1 analogs are currently available in treating diabetes with widely established safety and extensively evaluated efficacy. In recent years, autophagy, as a critical lysosome-dependent self-degradative process to maintain homeostasis, has been shown to be involved in the vascular endothelium damage in diabetes. In this review, the GLP-1/GLP-1R system implicated in diabetic endothelial dysfunction and related autophagy mechanism underlying the pathogenesis of diabetic vascular complications are briefly presented. This review also highlights a possible crosstalk between autophagy and the GLP-1/GLP-1R axis in the treatment of diabetic angiopathy.

Immunosuppression with cyclosporine versus tacrolimus shows distinctive nephrotoxicity profiles within renal compartments

AIM

Calcineurin inhibitors (CNIs) are the backbone for immunosuppression after solid organ transplantation. Although successful in preventing kidney transplant rejection, their nephrotoxic side effects contribute to allograft injury. Renal parenchymal lesions occur for cyclosporine A (CsA) as well as for the currently favored tacrolimus (Tac). We aimed to study whether chronic CsA and Tac exposures, before reaching irreversible nephrotoxic damage, affect renal compartments differentially and whether related pathogenic mechanisms can be identified.

METHODS

CsA and Tac were administered chronically in wild type Wistar rats using osmotic minipumps over 4 weeks. Functional parameters were controlled. Electron microscopy, confocal, and 3D-structured illumination microscopy were used for histopathology. Clinical translatability was tested in human renal biopsies. Standard biochemical, RNA-seq, and proteomic technologies were applied to identify implicated molecular pathways.

RESULTS

Both drugs caused significant albeit differential damage in vasculature and nephron. The glomerular filtration barrier was more affected by Tac than by CsA, showing prominent deteriorations in endothelium and podocytes along with impaired VEGF/VEGFR2 signaling and podocyte-specific gene expression. By contrast, proximal tubule epithelia were more severely affected by CsA than by Tac, revealing lysosomal dysfunction, enhanced apoptosis, impaired proteostasis and oxidative stress. Lesion characteristics were confirmed in human renal biopsies.

CONCLUSION

We conclude that pathogenetic alterations in the renal compartments are specific for either treatment. Considering translation to the clinical setting, CNI choice should reflect individual risk factors for renal vasculature and tubular epithelia. As a step in this direction, we share protein signatures identified from multiomics with potential pathognomonic relevance.

Spatiotemporal Landscape of Kidney Tubular Responses to Glomerular Proteinuria

Key Points

Glomerular proteinuria induces large-scale changes in gene expression along the nephron. Increased protein uptake in the proximal tubule results in axial remodeling and injury. Increased protein delivery to the distal tubule causes dedifferentiation of the epithelium.

Background

Large increases in glomerular protein filtration induce major changes in body homeostasis and are associated with a higher risk of kidney functional decline and cardiovascular disease. We investigated how elevated protein exposure modifies the landscape of tubular function along the entire nephron, to understand the cellular changes that mediate these important clinical phenomena.

Methods

We conducted single-nucleus RNA sequencing, functional intravital imaging, and antibody staining to spatially map transport processes along the mouse kidney tubule. We then delineated how these were altered in a transgenic mouse model of inducible glomerular proteinuria (POD-ATTAC) at 7 and 28 days.

Results

Glomerular proteinuria activated large-scale and pleiotropic changes in gene expression in all major nephron sections. Extension of protein uptake from early (S1) to later (S2) parts of the proximal tubule initially triggered dramatic expansion of a hybrid S1/2 population, followed by injury and failed repair, with the cumulative effect of loss of canonical S2 functions. Proteinuria also induced acute injury in S3. Meanwhile, overflow of luminal proteins to the distal tubule caused transcriptional convergence between specialized regions and generalized dedifferentiation.

Conclusions

Proteinuria modulated cell signaling in tubular epithelia and caused distinct patterns of remodeling and injury in a segment-specific manner.

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Calcium signaling crosstalk between the endoplasmic reticulum and mitochondria, a new drug development strategies of kidney diseases

Calcium (Ca2+) acts as a second messenger and constitutes a complex and large information exchange system between the endoplasmic reticulum (ER) and mitochondria; this process is involved in various life activities, such as energy metabolism, cell proliferation and apoptosis. Increasing evidence has suggested that alterations in Ca2+ crosstalk between the ER and mitochondria, including alterations in ER and mitochondrial Ca2+ channels and related Ca2+ regulatory proteins, such as sarco/endoplasmic reticulum Ca2+-ATPase (SERCA), inositol 1,4,5-trisphosphate receptor (IP3R), and calnexin (CNX), are closely associated with the development of kidney disease. Therapies targeting intracellular Ca2+ signaling have emerged as an emerging field in the treatment of renal diseases. In this review, we focused on recent advances in Ca2+ signaling, ER and mitochondrial Ca2+ monitoring methods and Ca2+ homeostasis in the development of renal diseases and sought to identify new targets and insights for the treatment of renal diseases by targeting Ca2+ channels or related Ca2+ regulatory proteins.

Delaying Renal Aging: Metformin Holds Promise as a Potential Treatment

Given the rapid aging of the population, age-related diseases have become an excessive burden on global health care. The kidney, a crucial metabolic organ, ages relatively quickly. While the aging process itself does not directly cause kidney damage, the physiological changes that accompany it can impair the kidney's capacity for self-repair. This makes aging kidneys more susceptible to diseases, including increased risks of chronic kidney disease and end-stage renal disease. Therefore, delaying the progression of renal aging and preserving the youthful vitality of the kidney are crucial for preventing kidney diseases. However, effective strategies against renal aging are still lacking due to the underlying mechanisms of renal aging, which have not been fully elucidated. Accumulating evidence suggests that metformin has beneficial effects in mitigating renal aging. Metformin has shown promising anti-aging results in animal models but has not been tested for this purpose yet in clinical trials. These findings indicate the potential of metformin as an anti-renal aging drug. In this review, we primarily discuss the characteristics and mechanisms of kidney aging and the potential effects of metformin against renal aging.