Thioredoxin-interacting protein mediates ER stress-induced β cell death through initiation of the inflammasome

Verapamil inhibits TXNIP-dependent NLRP3 Inflammasome activation in an ulcerative colitis rat model: A new evolving role of the calcium channel blocker

Ulcerative colitis (UC) is a long-term inflammatory bowel disease (IBD) associated with significant morbidity. It is marked by inflammation and damage to the colon's mucosal lining. Studies have shown that NLRP3 inflammasome activation, apoptosis, and impaired autophagy are critical in its pathogenesis. Verapamil, a calcium channel blocker, has been found to inhibit NLRP3 inflammasome activation in various preclinical models. However, the potential influence of verapamil on the TXNIP in UC remains unexplored. This study investigates the effects of verapamil on an UC rat model induced chemically by acetic acid. Verapamil effectively inhibited the TXNIP-NLRP3-caspase-1 axis, reducing inflammasome activation and the release of IL-1β and IL-18. Additionally, verapamil suppressed NFκB, the priming step of NLRP3 activation. The drug enhanced autophagic activity, as indicated by increased expression of LC3-II and Beclin-1, along with reduced LC3-I and mTOR expression. Moreover, it demonstrated anti-apoptotic effects mediated by regulating Bax and cleaved caspase-3. These molecular changes contributed to mucosal healing and improved microscopic and macroscopic outcomes in the colitis model. Furthermore, verapamil improved the colon weight-to-length ratio and disease activity scores and mitigated oxidative stress. As verapamil has been safely used in clinics to treat hypertension, our findings suggest it may be a safe therapeutic option for ameliorating inflammation and apoptosis and activating autophagy in UC pathology. Since hypertension demonstrates a strong association with UC, the use of verapamil merits particular attention in hypertensive patients fighting against IBD.

Unfolded protein response-activated NLRP3 inflammasome contributes to pyroptotic and apoptotic podocyte injury in diabetic kidney disease via the CHOP-TXNIP axis

BACKGROUND

Diabetic kidney disease (DKD) is the leading cause of chronic kidney disease and end-stage renal disease worldwide. Podocyte injury and death is a key event in DKD progression. Emerging evidence has indicated that crosstalk between unfolded protein response (UPR) and NLR family pyrin domain containing 3 (NLRP3) inflammasome plays an essential role in DKD progression. However, the involvement of these pathways in podocyte injury and death during DKD remains unclear.

RESULTS

Here, we found that inositol-requiring enzyme 1 (IRE1) and protein kinase RNA-like ER kinase (PERK) branches of the UPR, NLRP3 inflammasome, and apoptosis were activated in podocytes under DKD and high glucose (HG) conditions. In vitro, inducing ER stress by thapsigargin, and IRE1 or PERK overexpression upon HG treatment stimulated NLRP3 inflammasome-mediated pyroptosis and apoptosis, whereas inhibiting IRE1 or PERK suppressed them. Importantly, we discovered that the newly identified NLRP3-binding partner, thioredoxin-interacting protein (TXNIP), upon activation by the transcription factor (TF) PERK/CCAAT-enhancer-binding protein homologous protein (CHOP), served as a link between IRE1 or PERK branches with NLRP3 inflammasome-mediated pyroptosis and apoptosis. TXNIP expression was promoted in podocytes from DKD patients and db/db mice, as well as in HG-exposed conditionally immortalized human podocyte (HPC). In HG-exposed HPC, IRE1 or PERK overexpression upregulated TXNIP expression, while IRE1 or PERK inhibition downregulated it. TXNIP or CHOP silencing both inhibited HG-upregulated TXNIP, further blocking NLRP3 inflammasome-mediated pyroptosis and apoptosis. Furthermore, NLRP3 overexpression aggravated HG-induced pyroptosis and apoptosis, whereas additional TXNIP silencing reversed them without affecting IRE1 or PERK branches.

CONCLUSION

In conclusion, our results suggested that UPR/NLRP3 inflammasome-mediated pyroptosis/apoptosis pathway was involved in diabetic podocyte injury, and that targeting the CHOP-TXNIP axis may serve as a promising therapeutic target for DKD.

Effect of lipotoxic hepatocyte-derived extracellular vesicles in pancreas inflammation: essential role of macrophage TLR4 in beta cell functionality

AIMS/HYPOTHESIS

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a common feature of obesity and type 2 diabetes. Under lipotoxic stress, hepatocytes release small extracellular vesicles (sEVs) which act locally and contribute to MASLD progression, but their role in beta cell function and development of type 2 diabetes remains largely unexplored. We aimed to examine whether hepatocyte-derived sEVs (Hep-sEVs) under lipotoxic conditions impact on liver and pancreas inflammation and subsequent effects on beta cell function.

METHODS

Primary mouse hepatocytes and Huh7 human hepatocytes were treated with palmitic acid and Hep-sEVs were purified from the culture medium by differential ultracentrifugation. In vitro and in vivo approaches were used to decipher the role of Hep-sEVs in liver and pancreas inflammation and beta cell dysfunction in mouse and human pancreatic islets. The contribution of the Toll-like receptor 4 (TLR4) to Hep-sEV-mediated effects was investigated in pancreatic islets from myeloid-specific TLR4-deficient mice.

RESULTS

Lipotoxic Hep-sEVs targeted pancreatic islet macrophages and induced TLR4-mediated inflammation. The subsequent inflammatory response downregulated beta cell identity genes and impaired glucose-stimulated insulin secretion in both INS-1 beta cells (p<0.05) and isolated pancreatic islets from mice (p<0.01) and humans (p<0.05). Specific deletion of TLR4 in macrophages protected pancreatic islets against inflammation and the impairment of glucose-stimulated insulin secretion induced by lipotoxic Hep-sEVs. Chronic administration of lipotoxic Hep-sEVs in lean mice induced liver and pancreas inflammation through the recruitment of immune cells. This intervention induced hepatocyte injury and fibrotic damage together with detrimental immunometabolic systemic effects. Insulin resistance in hepatocytes (p<0.01) and a compensatory insulin secretion (p<0.001) that prevented glucose intolerance were also observed in mice treated with lipotoxic Hep-sEVs.

CONCLUSIONS/INTERPRETATION

This study has provided evidence of liver and pancreas inflammation and beta cell dysfunction induced by lipotoxic Hep-sEVs. Our data also envision TLR4-mediated signalling in islet macrophages as a key mediator of the effects of lipotoxic Hep-sEVs on beta cell function.

Genome editing of TXNIP in human pluripotent stem cells for the generation of hepatocyte-like cells and insulin-producing islet-like aggregates

BACKGROUND

Thioredoxin-interacting protein (TXNIP) plays a role in regulating endoplasmic reticulum (ER) and oxidative stress, which disrupt glucose homeostasis in diabetes. However, the impact of TXNIP deficiency on the differentiation and functionality of human stem cell-derived somatic metabolic cells remains unclear.

METHODS

We used CRISPR-Cas12a genome editing to generate TXNIP-deficient (TXNIP-/-) H1 human embryonic stem cells (H1-hESCs). These cells were differentiated into hepatocyte-like cells (HLCs) and stem-cell-derived insulin-producing islets (SC-islets). The maturation and functionality TXNIP-/- and TXNIP+/+ SC-islets were assessed by implantation under the kidney capsule of male or female NOD-SCID mice.

RESULTS

TXNIP deficiency significantly increased H1-hESC proliferation without affecting pluripotency, viability, or differentiation potential into HLCs and SC-islets. Bulk RNA-sequencing of thapsigargin-treated TXNIP-/- and TXNIP+/+ hESCs revealed differential expression of stress-responsive genes, with enriched apoptosis-related pathways in TXNIP+/+ cells, but minimal transcriptional changes specific to TXNIP deficiency. In HLCs, TXNIP deletion reduced albumin secretion and insulin signalling, as indicated by decreased AKT phosphorylation, while showing no differences in glycolytic activity or lipid metabolism markers. Under thapsigargin-induced ER stress, TXNIP-/- HLCs exhibited transiently reduced eIF2α phosphorylation and lower BiP expression, suggesting compromised adaptive responses to prolonged stress. SC-islets derived from TXNIP-/- hESCs showed comparable viability, endocrine cell composition, and cytokine responses to TXNIP+/+ islets. Following IFNα or IFNγ treatment, STAT1 phosphorylation was increased in TXNIP-/- SC-islets, indicating that IFN signalling remained intact despite TXNIP deficiency. Upon implantation into NOD-SCID mice, both TXNIP-/- and TXNIP+/+ SC-islets produced human C-peptide and responded to glucose stimulation. However, TXNIP-/- SC-islets did not demonstrate enhanced glycaemic control or glucose-stimulated insulin secretion compared to controls.

CONCLUSIONS

Our study demonstrates that TXNIP deficiency does not improve the differentiation or functionality of HLCs and SC-islets. We present the generation and characterisation of TXNIP-/- and TXNIP+/+ H1-hESCs, HLCs, and SC-islets as valuable models for future studies on the role of TXNIP in metabolic cell biology.

G protein-coupled estrogen receptor reduces the breast cancer cell survival by regulating the IRE1α/miR-17-5p/TXNIP pathway

This study aimed to explore whether GPER can induce the UPR response in the SKBR3 cell line through ER and IREα activation, and to assess whether this response leads to cell survival or cell death. Additionally, the study sought to evaluate the impact of this response on cell behaviors such as apoptosis, migration, and drug resistance. To activate the UPR and induce ER stress, we treated the MCF10A cell line with 0.5 µg/ml TUN for 24 and 48 h. The expression levels of XBP-1 and C/EBP homology protein (CHOP) genes (ER stress markers) were measured using the qRT-PCR technique. The MCF10A + TUN cell line was used as a positive control. To determine the optimal doses of G1 and tamoxifen (TAM), we evaluated GPER expression using qRT-PCR analysis. Cells were then treated with various doses of G1 (1000 nM), G15 (1000 nM), and TAM (2000 nM), both individually and in combination (G1 + G15, TAM + G15, G1 + TAM), for 24 and 48 h. We measured the expression of GPER, IRE1α, MiR-17-5p, TXNIP, ABCB1, and ABCC1 genes. Apoptosis was assessed via flow cytometry, and cell migration was examined using the wound-healing assay. Our results demonstrated that GPER activation by G1 and TAM significantly increased IRE1α expression in SKBR3 cells. This activation, through its RIDD activity, cleaved miR-17-5p and initiated the UPR death response. The upregulation of the TXNIP gene expression enhanced apoptosis and chemotherapy sensitivity while decreasing cell migration. Interestingly, these effects were notably reversed by G15 treatment. In summary, the GPER/IRE1α/miR-17-5p/TXNIP axis plays a key role in the UPR pro-death response, promoting programmed cell death, reducing migration, and decreasing drug resistance in SKBR3 cells.

Decoding ischemic stroke: Perspectives on the endoplasmic reticulum, mitochondria, and their crosstalk

Stroke is known for its high disability and mortality rates. Ischemic stroke (IS), the most prevalent form, imposes a considerable burden on affected individuals. Nevertheless, existing treatment modalities are hindered by limitations, including narrow therapeutic windows, substantial adverse effects, and suboptimal neurological recovery. Clarifying the pathological mechanism of IS is a prerequisite for developing new therapeutic strategies. In this context, the functional disruption of mitochondria, the endoplasmic reticulum (ER), and the crosstalk mechanisms between them have garnered increasing attention for their contributory roles in the progression of IS. Therefore, this review provides a comprehensive summary of the current pathomechanisms associated with the involvement of the ER and mitochondria in IS, emphasising Ca2+ destabilization homeostasis, ER stress, oxidative stress, disordered mitochondrial quality control, and mitochondrial transfer. Additionally, this article highlights the functional interaction between the ER and mitochondria, as well as the mitochondrial-ER contacts (MERCs) that structurally connect mitochondria and the ER, aiming to provide ideas and references for the research and treatment of IS.

The endoplasmic reticulum-mitochondrial crosstalk involved in nanoplastics and di(2-ethylhexyl) phthalate co-exposure induced the damage to mouse mammary epithelial cells

With the extensive use of plastic products, significant amounts of microplastics, nanoplastic particles (NPs), and plasticizers such as Di(2-ethylhexyl) phthalate (DEHP) are continuously released into the environment. However, the toxic effects of NPs alone or in combination with DEHP on mammary glands remain unreported. This study investigates the impacts of NPs and DEHP on the structure and function of mouse mammary epithelial cells and elucidates the underlying molecular mechanisms. We found that co-exposure to NPs and DEHP induced severe pyroptosis, inflammation and oxidative stress in HC11 cells. Co-exposure also caused mitochondrial damage, as evidenced by changes in mitochondrial membrane potential, increase in mitochondrial ROS and inhibition of ATP production. Moreover, NPs and DEHP co-exposure increased the transcriptional levels of endoplasmic reticulum (ER) stress-related genes, activated the inflammation-related NLRP3 signaling pathway, and damaged the cell membrane integrity. Notably, Co-exposure enhanced the ER-mitochondria crosstalk in HC11 cells, as evidenced by the upregulated transcriptional levels of ER Ca2+ channel proteins (Ip3r1, Grp75 and Vdac1), increased mitochondrial Ca2+ levels, and expanded mitochondrial-ER contact areas. In summary, this study revealed that NPs and DEHP co-exposure had the potential to induce pyroptosis and inflammation by enhancing the ER-mitochondria crosstalk, ultimately resulting in injury to mammary glands. These findings would provide some new insights into the molecular mechanisms underlying the toxic effects of NPs and DEHP to mammary glands.

Endoplasmic reticulum stress: A key player in immune cell regulation and autoimmune disorders

The endoplasmic reticulum (ER) is a large organelle, found in all eukaryotes, that is essential for normal cellular function. This function encompasses protein folding and quality control, post-translational modifications, lipid regulation, and the storage of intracellular calcium, among others. These diverse processes are essential for maintaining proteome stability. Therefore, a robust surveillance system is established under stress to ensure cell homeostasis. Sources of stress can originate from the cellular environment, including nutrient deprivation, hypoxia, and low pH, as well as from endogenous signals within the cell, such as metabolic challenges and increased demands for protein production. When cellular homeostasis is altered by one of these triggers, ER primary functions are altered which leads to the accumulation of misfolded proteins. These impaired proteins trigger the activation of the Unfolded Protein Response (UPR) pathway. This response aims at reducing ER stress by implementing the induction of complex programs to restore cell homeostasis. However, extended ER stress can modify the UPR response, shifting its signals from promoting survival to triggering pathways that reprogram or eliminate affected cells.

Targeting IRE1α improves insulin sensitivity and thermogenesis and suppresses metabolically active adipose tissue macrophages in male obese mice

Overnutrition engenders the expansion of adipose tissue and the accumulation of immune cells, in particular, macrophages, in the adipose tissue, leading to chronic low-grade inflammation and insulin resistance. In obesity, several proinflammatory subpopulations of adipose tissue macrophages (ATMs) identified hitherto include the conventional 'M1-like' CD11C-expressing ATM and the newly discovered metabolically activated CD9-expressing ATM; however, the relationship among ATM subpopulations is unclear. The ER stress sensor inositol-requiring enzyme 1α (IRE1α) is activated in the adipocytes and immune cells under obesity. It is unknown whether targeting IRE1α is capable of reversing insulin resistance and obesity and modulating the metabolically activated ATMs. We report that pharmacological inhibition of IRE1α RNase significantly ameliorates insulin resistance and glucose intolerance in male mice with diet-induced obesity. IRE1α inhibition also increases thermogenesis and energy expenditure, and hence protects against high fat diet-induced obesity. Our study shows that the 'M1-like' CD11c+ ATMs are largely overlapping with but yet non-identical to CD9+ ATMs in obese white adipose tissue. Notably, IRE1α inhibition diminishes the accumulation of obesity-induced metabolically activated ATMs and 'M1-like' ATMs, resulting in the curtailment of adipose inflammation and ensuing reactivation of thermogenesis, without augmentation of the alternatively activated M2 macrophage population. Our findings suggest the potential of targeting IRE1α for the therapeutic treatment of insulin resistance and obesity.

Beyond Redox Regulation: Novel Roles of TXNIP in the Pathogenesis and Therapeutic Targeting of Kidney Disease

Cellular stress, such as oxidative and endoplasmic reticulum (ER) stresses, contributes to the development of various kidney diseases. Oxidative stress is prompted by reactive oxygen species accumulation and delicately mitigated by glutathione and thioredoxin (Trx) antioxidant systems. Initially identified as a Trx-binding partner, Trx-interacting protein (TXNIP) is significantly up-regulated and activated by oxidative and ER stresses. The function of TXNIP is closely linked to its subcellular localizations. Under normal physiological conditions, TXNIP primarily localizes to the nucleus. When exposed to reactive oxygen species or ER stress, TXNIP relocates to mitochondria and binds to mitochondrial Trx2, which releases Trx-tethered apoptosis signal-regulating kinase 1 and activates apoptosis signal-regulating kinase 1-mediated apoptosis. Oxidative and ER stresses are also closely associated with autophagy. TXNIP can promote or inhibit autophagy depending on context. Although recent studies have highlighted the indispensable role of TXNIP in the etiology and progression of kidney disease, TXNIP-targeted therapy is still missing. This review focuses on the following: i) oxidative and ER stresses; ii) regulation and function of TXNIP during cellular stress; iii) TXNIP in stress-regulated autophagy; iv) TXNIP in kidney diseases (nephrotic syndrome, diabetic nephropathy and chronic kidney disease, acute kidney injury, and kidney aging); and v) novel treatment agents targeting TXNIP in kidney disease. Current advances in chemical compounds and RNA-based therapy suppressing TXNIP are also reviewed.

The Chicken or the Egg Dilemma: Understanding the Interplay between the Immune System and the β Cell in Type 1 Diabetes

In this review, we explore the complex interplay between the immune system and pancreatic β cells in the context of type 1 diabetes (T1D). While T1D is predominantly considered a T-cell-mediated autoimmune disease, the inability of human leukocyte antigen (HLA)-risk alleles alone to explain disease development suggests a role for β cells in initiating and/or propagating disease. This review delves into the vulnerability of β cells, emphasizing their susceptibility to endoplasmic reticulum (ER) stress and protein modifications, which may give rise to neoantigens. Additionally, we discuss the role of viral infections as contributors to T1D onset, and of genetic factors with dual impacts on the immune system and β cells. A greater understanding of the interplay between environmental triggers, autoimmunity, and the β cell will not only lead to insight as to why the islet β cells are specifically targeted by the immune system in T1D but may also reveal potential novel therapeutic interventions.

Prenatal Inflammatory Exposure Predisposes Offspring to Chronic Kidney Diseases Via the Activation of the eIF2α-ATF4 Pathway

It has recently become more recognized that renal diseases in adults can originate from adverse intrauterine (maternal) environmental exposures. Previously, we found that prenatal lipopolysaccharide (LPS) exposure can result in chronic renal inflammation, which leads to renal damage in older offspring rats. To test whether prenatal inflammatory exposure predisposes offspring to renal damage, a mouse model of oral adenine consumption-induced chronic kidney disease (CKD) was applied to offspring from prenatal LPS-treated mothers (offspring-pLPS) and age-matched control offspring of prenatal saline-treated mothers (offspring-pSaline). We found that offspring-pLPS mice presented with more severe renal collagen deposition and renal dysfunction after 4 weeks of adenine consumption than sex- and treatment-matched offspring-pSaline controls. To illustrate the underlying molecular mechanism, we subjected offspring-pLPS and offspring-pSaline kidneys to genome-wide transcriptomic analysis. Bioinformatic analysis of the sequencing data, together with further experimental confirmation, revealed a strong activation of the PERK-eIF2α-ATF4-mediated unfolded protein response (UPR) in offspring-pLPS kidneys, which likely contributed to the CKD predisposition seen in offspring-pLPS mice. More importantly, the specific eIF2α-ATF4 signaling inhibitor ISIRB was able to prevent adenine-induced CKD in the offspring-pLPS mice. Our findings suggest that the eIF2α-ATF4-mediated UPR, but not PERK, is likely the major disease-causing pathway in prenatal inflammatory exposure-induced CKD predisposition. Our study also suggests that targeting this signaling pathway is a potentially promising approach for CKD treatment.

Redox signaling in the pancreas in health and disease

This review addresses oxidative stress and redox signaling in the pancreas under healthy physiological conditions as well as in acute pancreatitis, chronic pancreatitis, pancreatic cancer, and diabetes. Physiological redox homeodynamics is maintained mainly by NRF2/KEAP1, NF-κB, protein tyrosine phosphatases, peroxisome proliferator-activated receptor-γ coactivator 1α (PGC1α), and normal autophagy. Depletion of reduced glutathione (GSH) in the pancreas is a hallmark of acute pancreatitis and is initially accompanied by disulfide stress, which is characterized by protein cysteinylation without increased glutathione oxidation. A cross talk between oxidative stress, MAPKs, and NF-κB amplifies the inflammatory cascade, with PP2A and PGC1α as key redox regulatory nodes. In acute pancreatitis, nitration of cystathionine-β synthase causes blockade of the transsulfuration pathway leading to increased homocysteine levels, whereas p53 triggers necroptosis in the pancreas through downregulation of sulfiredoxin, PGC1α, and peroxiredoxin 3. Chronic pancreatitis exhibits oxidative distress mediated by NADPH oxidase 1 and/or CYP2E1, which promotes cell death, fibrosis, and inflammation. Oxidative stress cooperates with mutant KRAS to initiate and promote pancreatic adenocarcinoma. Mutant KRAS increases mitochondrial reactive oxygen species (ROS), which trigger acinar-to-ductal metaplasia and progression to pancreatic intraepithelial neoplasia (PanIN). ROS are maintained at a sufficient level to promote cell proliferation, while avoiding cell death or senescence through formation of NADPH and GSH and activation of NRF2, HIF-1/2α, and CREB. Redox signaling also plays a fundamental role in differentiation, proliferation, and insulin secretion of β-cells. However, ROS overproduction promotes β-cell dysfunction and apoptosis in type 1 and type 2 diabetes.

Target Discovery to Diabetes Therapy-TXNIP From Bench to Bedside With NIDDK

Diabetes is the most expensive chronic disease in the United States, with more than $400 billion in annual costs, and it affects more than 38 million Americans. While major advances in drug treatment have been made for type 2 diabetes (T2D) and the often-associated obesity, there are still no approved and effective medications targeting β-cell loss or islet dysfunction, which is one of the major underlying causes of both type 1 diabetes (T1D) and T2D. In addition, there are no oral medications for T1D approved in the United States more than 100 years after the discovery of insulin, and attractive therapeutic targets are only starting to emerge. As we celebrate the 75th anniversary of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), progress is finally being made in this area with NIDDK support. This mini-review follows the discovery of thioredoxin-interacting protein inhibitors as an example of a methodical approach to identify and develop an oral β-cell treatment for T1D. It further discusses how the initial molecular findings were translated into novel clinical treatment approaches that promote the patient's own islet health and β-cell function using drug repurposing as well as new drug discovery.

Breaking the Feedback Loop of β-Cell Failure: Insight into the Pancreatic β-Cell's ER-Mitochondria Redox Balance

Pancreatic β-cells rely on a delicate balance between the endoplasmic reticulum (ER) and mitochondria to maintain sufficient insulin stores for the regulation of whole animal glucose homeostasis. The ER supports proinsulin maturation through oxidative protein folding, while mitochondria supply the energy and redox buffering that maintain ER proteostasis. In the development of Type 2 diabetes (T2D), the progressive decline of β-cell function is closely linked to disruptions in ER-mitochondrial communication. Mitochondrial dysfunction is a well-established driver of β-cell failure, whereas the downstream consequences for ER redox homeostasis have only recently emerged. This interdependence of ER-mitochondrial functions suggests that an imbalance is both a cause and consequence of metabolic dysfunction. In this review, we discuss the regulatory mechanisms of ER redox control and requirements for mitochondrial function. In addition, we describe how ER redox imbalances may trigger mitochondrial dysfunction in a vicious feed forward cycle that accelerates β-cell dysfunction and T2D onset.

Molecular glues of the regulatory ChREBP/14-3-3 complex protect beta cells from glucolipotoxicity

The Carbohydrate Response Element Binding Protein (ChREBP) is a glucose-responsive transcription factor (TF) with two major splice isoforms (α and β). In chronic hyperglycemia and glucolipotoxicity, ChREBPα-mediated ChREBPβ expression surges, leading to insulin-secreting β-cell dedifferentiation and death. 14-3-3 binding to ChREBPα results in cytoplasmic retention and suppression of transcriptional activity. Thus, small molecule-mediated stabilization of this protein-protein interaction (PPI) may be of therapeutic value. Here, we show that structure-based optimizations of a 'molecular glue' compound led to potent ChREBPα/14-3-3 PPI stabilizers with cellular activity. In primary human β-cells, the most active compound retained ChREBPα in the cytoplasm, and efficiently protected β-cells from glucolipotoxicity while maintaining β-cell identity. This study may thus not only provide the basis for the development of a unique class of compounds for the treatment of Type 2 Diabetes but also showcases an alternative 'molecular glue' approach for achieving small molecule control of notoriously difficult to target TFs.

PDIA4 targets IRE1α/sXBP1 to alleviate NLRP3 inflammasome activation and renal tubular injury in diabetic kidney disease

The role of ER stress in the pathogenesis of diabetic kidney diseases (DKD) remains unclear. We employed bioinformatics to identify the UPR pathway activation, inflammation, and programmed cell death patterns in diabetic tubules. Levels of IRE1α/sXBP1 signaling, NLRP3 inflammasome activity and pyroptosis in tubular cells under high glucose conditions were measured. IRE1α knockdown was used to determine its role in glucose-triggered activation of the NLRP3 inflammasome and pyroptosis. PDIA4 overexpression and silencing were used to assess its impact on the IRE1α/sXBP1 pathway. The dynamic interaction among PDIA4, GRP78, and IRE1α under high glucose were analyzed using immunoprecipitation and crosslinking assays. In STZ-induced and db/db mouse models of DKD, the regulatory role of PDIA4 on IRE1α/sXBP1 signaling and diabetic tubular inflammation and injury were evaluated. Our study showed that IRE1α/sXBP1, NLRP3 inflammasome, and pyroptosis are activated in the renal tubules of DKD patients. Induction of IRE1α pathway mediated the glucose-triggered activation of the NLRP3 inflammasome and pyroptosis. Moreover, overexpression of PDIA4 decreased the activation of IRE1α/sXBP1 under high glucose conditions. High glucose leads to the release of GRP78 from IRE1α and an increased interaction between IRE1α and PDIA4. In mouse models of DKD, overexpressing PDIA4 mitigated diabetic tubular injury and inflammation, marked by decreased IRE1α/sXBP1 and NLRP3 inflammasome. In conclusion, our findings demonstrate that high glucose triggers NLRP3 inflammasome and pyroptosis via the IRE1α/sXBP1 pathway in renal tubular cells. Overexpression of PDIA4 suppresses IRE1α signaling by binding to its oligomeric form, implying a promising therapeutic intervention for DKD.

Regulation of FOXM1 by HDAC3 Inhibition Ameliorates Macrophage Endoplasmic Reticulum stress and Apoptosis in Mycobacterium tuberculosis Infection

Mycobacterium tuberculosis (Mtb) infection may induce significant damage to the host lung tissues. Endoplasmic reticulum stress (ERS) and apoptosis of macrophages are considered key factors affecting the survival and pathogenicity of intracellular Mtb. Forkhead box M1 (FOXM1) is closely implicated in lung diseases. This study aimed to investigate the role of FOXM1 in Mtb infection and the involvement of histone deacetylase 3 (HDAC3) in this process. An in vitro Mtb infection model was established by infecting RAW264.7 macrophages with Mtb H37Ra. The results showed that RAW264.7 macrophages subjected to Mtb infection showed upregulated expressions of ERS markers and FOXM1. FOXM1 overexpression further elevated the levels of ERS and apoptosis markers, pro-inflammatory cytokines, and reactive oxygen species in Mtb-infected macrophages. FOXM1 could bind to the promoter of TXNIP and activate its transcription. Knockdown of TXNIP suppressed the effects of Mtb infection on macrophages, while upregulation of FOXM1 completely abolished the effects of TXNIP knockdown. HDAC3 inhibitor effectively diminished the effects of FOXM1 upregulation on Mtb-infected macrophages. In conclusion, inhibition of HDAC3 may reduce ERS and apoptosis of Mtb-infected macrophages by regulating the FOXM1/TXNIP axis.

FOXO regulation of TXNIP induces ferroptosis in satellite cells by inhibiting glutathione metabolism, promoting Sarcopenia

Aging-related sarcopenia represents a significant health concern due to its impact on the quality of life in the elderly. This study elucidates the molecular mechanisms underlying sarcopenia by employing single-cell sequencing and public transcriptome databases to compare young and aged mouse skeletal muscles. Cellular classification and pseudotime analyses differentiated cell types and their interrelationships, revealing a marked reduction in satellite cell numbers and a consistent upregulation of TXNIP (Thioredoxin interacting protein) across various muscle cell populations in aged mice. Further transcriptomic data integration and batch correction from the GEO (Gene Expression Omnibus) database highlighted key differentially expressed genes. The role of TXNIP and its transcriptional regulation by FOXO1 (Forkhead box O1) was confirmed through in vitro experiments, which demonstrated FOXO1's influence on TXNIP expression and its subsequent suppression of glutathione metabolism, leading to satellite cell ferroptosis. Additionally, in vivo studies showed that overexpression of TXNIP in young mice's muscle tissues significantly reduced muscle mass, suggesting its potential role in the initiation of sarcopenia. Our findings suggest that FOXO1-mediated regulation of TXNIP and the disruption of glutathione metabolism are central to the process of sarcopenia, offering new insights into its pathogenesis.

Integrated network pharmacology, molecular docking and in vivo experiments to elucidate the extenuative mechanisms of ginseng polysaccharide against Toxoplasma gondii-induced testicular toxicity

Toxoplasma gondii (T. gondii) causes obvious reproductive toxicity in male by inducing inflammation and apoptosis in testicular tissue. Ginseng polysaccharide (GP) is an active compound in ginseng, known for its remarkable anti-inflammatory and antioxidant properties. This study aimed to investigate the effects of GP against T. gondii-induced testicular injury by integrating network pharmacology and in vivo experiments. Totally 9 core targets were identified, and PI3K/AKT1 signaling pathway were enriched via the network pharmacology analysis of GP against T. gondii-induced testicular injury, and molecular docking indicated that TLR4-related inflammatory pathways and Bax-related apoptotic pathways were also involved. In vivo experiments showed that GP (100 or 200 mg/kg) mitigated the histopathology damage, enhanced spermatogenic capacity of the testis, and increased the levels of testosterone, luteinizing hormone and follicular-stimulating hormone in the serum. Proteins related to testosterone biosynthesis, StAR, P450scc and 17β-HSD, were significantly up-regulated. GP also inhibited the levels of inflammatory factors, by inhibiting the TLR4-P2X7R/NLRP3 inflammatory pathway in the testicular tissue. In addition, GP remarkably decreased testicular cell apoptosis rate, activated the PI3K/AKT pathway, and remarkably inhibited the apoptosis-associated PERK/eIF2α/ATF4/CHOP endoplasmic reticulum (ER) stress signaling pathway. In conclusion, the extenuative mechanisms of GP against T. gondii-induced testicular toxicity were comprehensively identified through integrating network pharmacology with in vivo experiments, it suggested that GP alleviates T. gondii-induced testicular toxicity by inhibiting the TLR4-P2X7R/NLRP3 inflammatory and PERK/eIF2α/ATF4/CHOP ER stress signaling pathways. This study provides new evidence for further development of ginseng as healthcare products to improve male reproductive function in T. gondii-infected patients.

Forsythiaside A alleviates myocardial injury in streptozotocin-induced diabetes via endoplasmic reticulum stress-NLRP3 inflammasome pathway

The aim of this study was to evaluate for the effects of forsythiaside A (FA) on myocardial injury in streptozotocin (STZ)-induced diabetes mice. Blood glucose (BG), serum triglycerides (TG), lactate dehydrogenase (LDH), creatine kinase isoenzyme (CK-MB), cardiac troponin (cTnI), malondialdehyde (MDA), superoxide dismutase (SOD) levels were detected in STZ mice. The structure and function of heart was observed via cardiac ultrasound. Cytokine levels in mouse serum and heart were detected using enzyme-linked immunosorbent assay (ELISA) as well as TG, LDH, CK-MB, cTnI, MDA and SOD in high glucose (Glu) induced H9c2 cells. Western blot detection of the expression of endoplasmic reticulum stress-related TXNIP/NLRP3 inflammasome pathways (GRP78, PERK, P-PERK, EIF-α, P-EIF-α, XBP1, ATF6, TXNIP and NLRP3) in SCD mice and LCG induced H9c2 cells. Endoplasmic reticulum stress activator tunicamycin (TM) was used to validate the above pathway for FA. It was also found that FA had protective effects on myocardial injury in STZ mice via restored heart function, improved cardiac pathological changes and suppressed inflammatory response as well as in Glu induced H9c2 cells. In conclusion, FA alleviated myocardial injury in diabetes via endoplasmic reticulum stress-NLRP3 inflammasome pathway.

Targeting IRE1α improves insulin sensitivity and thermogenesis and suppresses metabolically active adipose tissue macrophages in male obese mice

Overnutrition engenders the expansion of adipose tissue and the accumulation of immune cells, in particular, macrophages, in the adipose tissue, leading to chronic low-grade inflammation and insulin resistance. In obesity, several proinflammatory subpopulations of adipose tissue macrophages (ATMs) identified hitherto include the conventional "M1-like" CD11C-expressing ATM and the newly discovered metabolically activated CD9-expressing ATM; however, the relationship among ATM subpopulations is unclear. The ER stress sensor inositol-requiring enzyme 1α (IRE1α) is activated in the adipocytes and immune cells under obesity. It is unknown whether targeting IRE1α is capable of reversing insulin resistance and obesity and modulating the metabolically activated ATMs. We report that pharmacological inhibition of IRE1α RNase significantly ameliorates insulin resistance and glucose intolerance in male mice with diet-induced obesity. IRE1α inhibition also increases thermogenesis and energy expenditure, and hence protects against high fat diet-induced obesity. Our study shows that the "M1-like" CD11c+ ATMs are largely overlapping with but yet non-identical to CD9+ ATMs in obese white adipose tissue. Notably, IRE1α inhibition diminishes the accumulation of obesity-induced metabolically activated ATMs and "M1-like" ATMs, resulting in the curtailment of adipose inflammation and ensuing reactivation of thermogenesis, without augmentation of the alternatively activated M2 macrophage population. Our findings suggest the potential of targeting IRE1α for the therapeutic treatment of insulin resistance and obesity.

Overcoming β-Cell Dysfunction in Type 2 Diabetes Mellitus: CD36 Inhibition and Antioxidant System

Type 2 diabetes mellitus (T2DM) is marked by chronic hyperglycemia, gradually worsening β-cell failure, and insulin resistance. Glucotoxicity and oxidative stress cause β-cell failure by increasing reactive oxygen species (ROS) production, impairing insulin secretion, and disrupting transcription factors such as pancreatic and duodenal homeobox 1 (PDX-1) and musculoaponeurotic fibrosarcoma oncogene family A (MafA). Cluster determinant 36 (CD36), an essential glycoprotein responsible for fatty acid uptake, exacerbates oxidative stress and induces the apoptosis of β-cells under hyperglycemic conditions through pathways involving ceramide, thioredoxin-interacting protein (TXNIP), and Rac1-nicotinamide adenine dinucleotide phosphate oxidase (NOX)-mediated redoxosome formation. Targeting CD36 pathways has emerged as a promising therapeutic strategy. Oral hypoglycemic agents, such as metformin, teneligliptin, and pioglitazone, have shown protective effects on β-cells by enhancing antioxidant defenses. These agents reduce glucotoxicity via mechanisms such as suppressing CD36 expression and stabilizing mitochondrial function. Additionally, novel insights into the glutathione antioxidant system and its role in β-cell survival underscore its therapeutic potential. This review focuses on the key contribution of oxidative stress and CD36 to β-cell impairment, the therapeutic promise of antioxidants, and the need for further research to apply these findings in clinical practice. Promising strategies targeting these mechanisms may help preserve β-cell function and slow T2DM progression.

Understanding the impact of ER stress on lung physiology

Human lungs consist of a distinctive array of cell types, which are subjected to persistent challenges from chemical, mechanical, biological, immunological, and xenobiotic stress throughout life. The disruption of endoplasmic reticulum (ER) homeostatic function, triggered by various factors, can induce ER stress. To overcome the elevated ER stress, an adaptive mechanism known as the unfolded protein response (UPR) is activated in cells. However, persistent ER stress and maladaptive UPR can lead to defects in proteostasis at the cellular level and are typical features of the lung aging. The aging lung and associated lung diseases exhibit signs of ER stress-related disruption in cellular homeostasis. Dysfunction resulting from ER stress and maladaptive UPR can compromise various cellular and molecular processes associated with aging. Hence, comprehending the mechanisms of ER stress and UPR components implicated in aging and associated lung diseases could enable to develop appropriate therapeutic strategies for the vulnerable population.

Comparison of Endoplasmic Reticulum Stress and Pyroptosis Induced by Pathogenic Calcium Oxalate Monohydrate and Physiologic Calcium Oxalate Dihydrate Crystals in HK-2 Cells: Insights into Kidney Stone Formation

Endoplasmic reticulum stress (ERS) can activate pyroptosis through CHOP and TXNIP; however, the correlation between this process and the formation of kidney stones has not been reported. The purpose is to investigate the effects of calcium oxalate monohydrate (COM) and calcium oxalate dihydrate (COD) on ERS and pyroptosis in HK-2 cells and to explore the formation mechanism of calcium oxalate stones. HK-2 cells were injured by 3 μm COM and COD. COM and COD significantly upregulated the expression levels of GRP78, CHOP, TXNIP, and pyroptosis-related proteins (NLRP3, caspase-1, GSDMD-N, and IL-1β). Fluorescence colocalization revealed that COM induced pyroptosis by inducing the interaction between TXNIP and NLRP3. Both COM and COD crystals can induce ERS and pyroptosis in HK-2 cells. COM induces the interaction with NLRP3 by the upregulation of CHOP and TXNIP and then promotes pyroptosis, while COD only promotes pyroptosis by the upregulation of CHOP. The cytotoxicity and the ability of COM to promote crystal adhesion and aggregation are higher than COD, suggesting that COM is more dangerous for calcium oxalate kidney stone formation.

Endoplasmic Reticulum Stress Induces ROS Production and Activates NLRP3 Inflammasome Via the PERK-CHOP Signaling Pathway in Dry Eye Disease

Purpose

The purpose of this study was to investigate the potential roles of endoplasmic reticulum (ER) stress in the development of dry eye disease (DED).

Methods

Single-cell RNA sequencing (scRNA-seq) data from the Gene Expression Omnibus (GEO) database, derived from corneal tissues of a dry eye mouse model, was processed using the Seurat R program. The results were validated using a scopolamine-induced dry eye mouse model and a hyperosmotic-induced cell model involving primary human corneal epithelial cells (HCECs) and immortalized human corneal epithelial (HCE-2) cells. The HCE-2 cells were treated with 4-phenylbutyric acid (4-PBA) or tunicamycin (TM) to modulate ER stress. TXNIP and PERK knockdown were performed by siRNA transfection. Immunofluorescence, Western blotting, and real-time PCR were used to assess oxidative stress, ER stress, unfolded protein response (UPR) marker proteins, and TXNIP/NLRP3 axis activation.

Results

The analysis of scRNAseq data shows an increase in the ER stress marker GRP78, and the activation of the PERK-CHOP of UPR in DED mouse. These findings were confirmed both in vivo and in vitro. Additionally, HCE-2 cells treated with 4-PBA or TM showed significant effects on the production of reactive oxygen species (ROS) and the activation of the TXNIP/NLRP3-IL1β signaling pathway. Furthermore, siRNA knockdown of PERK or TXNIP, which alleviated the TXNIP/NLRP3-IL1β signaling axis, showed protective effects on HCECs.

Conclusions

This study explores the role of ER stress-induced oxidative stress and NLRP3-IL-1β mediated inflammation in DED, and highlights the therapeutic potential of PERK-CHOP axis and TXNIP in the treatment of DED.

The stimulatory effect of HI 129, a novel indole derivative, on glucose-induced insulin secretion

Indole derivatives exhibit a broad spectrum of beneficial effects, encompassing anti-inflammatory, antiviral, antimalarial, anti-diabetic, antioxidant, anti-hepatitis, and antidepressant properties. Here, we describe the potentiation of insulin secretion in pancreatic islets and INS-1 cells through methyl 2-(2-ethoxy-1-hydroxy-2-oxoethyl)-1-(pyrimidine-2-yl)-1H-indole-3-carboxylate (HI 129), a novel indole derivative. Treatment with HI 129 led to notably decreased ADP/ATP ratios in pancreatic islets and INS-1 cells compared to those in the vehicle-treated controls, indicating a shift in cellular ATP production. Moreover, the augmentation of insulin secretion by HI 129 was closely correlated with its ability to enhance the mitochondrial membrane potential and respiration, partly by reducing the phosphorylation levels of AMP-activated protein kinase (AMPK). Mechanistically, HI 129 enhanced the association between AMPK and β-arrestin-1, critical molecules for glucose-induced insulin secretion. Furthermore, β-arrestin-1 depletion attenuated the effect of HI 129 on glucose-induced insulin secretion, suggesting that HI 129 potentiates insulin secretion via β-arrestin-1/AMPK signaling. These results collectively underscore the potential of HI 129 in enhancing insulin secretion as a novel candidate for improving glucose homeostasis in type 2 diabetes.

Inhibition of IRE1α/XBP1 axis alleviates LPS-induced acute lung injury by suppressing TXNIP/NLRP3 inflammasome activation and ERK/p65 signaling pathway

BACKGROUND

Acute lung injury or acute respiratory distress syndrome (ALI/ARDS) is a devastating clinical syndrome with high incidence and mortality rates. IRE1α-XBP1 pathway is one of the three major signaling axes of endoplasmic reticulum stress that is involved in inflammation, metabolism, and immunity. The role and potential mechanisms of IRE1α-XBP1 axis in ALI/ARDS has not well understood.

METHODS

The ALI murine model was established by intratracheal administration of lipopolysaccharide (LPS). Hematoxylin and eosin (H&E) staining and analysis of bronchoalveolar lavage fluid (BALF) were used to evaluate degree of lung injury. Inflammatory responses were assessed by ELISA and RT-PCR. Apoptosis was evaluated using TUNEL staining and western blot. Moreover, western blot, immunohistochemistry, and immunofluorescence were applied to test expression of IRE1α, XBP1, NLRP3, TXNIP, IL-1β, ERK1/2 and NF-κB p65.

RESULTS

The expression of IRE1α significantly increased after 24 h of LPS treatment. Inhibition of the IRE1α-XBP1 axis with 4µ8C notably improved LPS-induced lung injury and inflammatory infiltration, reduced the levels of IL-6, IL-1β, and TNF-α, and decreased cell apoptosis as well as the activation of the NLRP3 inflammasome. Besides, in LPS-stimulated Beas-2B cells, both 4µ8C and knockdown of XBP1 diminished the mRNA levels of IL-6 and IL-1B, inhibited cell apoptosis and reduced the protein levels of TXNIP, NLRP3 and secreted IL-1β. Mechanically, the phosphorylation and nuclear translocation of ERK1/2 and p65 were significantly suppressed by 4µ8C and XBP1 knockdown.

CONCLUSIONS

In summary, our findings suggest that IRE1α-XBP1 axis is crucial in the pathogenesis of ALI/ARDS, whose suppression could mitigate the pulmonary inflammatory response and cell apoptosis in ALI through the TXNIP/NLRP3 inflammasome and ERK/p65 signaling pathway. Our study may provide new evidence that IRE1α-XBP1 may be a promising therapeutic target for ALI/ARDS.

Molecular glues of the regulatory ChREBP/14-3-3 complex protect beta cells from glucolipotoxicity

The Carbohydrate Response Element Binding Protein (ChREBP) is a glucose-responsive transcription factor (TF) with two major splice isoforms (α and β). In chronic hyperglycemia and glucolipotoxicity, ChREBPα-mediated ChREBPβ expression surges, leading to insulin-secreting β-cell dedifferentiation and death. 14-3-3 binding to ChREBPα results in cytoplasmic retention and suppression of transcriptional activity. Thus, small molecule-mediated stabilization of this protein-protein interaction (PPI) may be of therapeutic value. Here, we show that structure-based optimizations of a 'molecular glue' compound led to potent ChREBPα/14-3-3 PPI stabilizers with cellular activity. In primary human β-cells, the most active compound retained ChREBPα in the cytoplasm, and efficiently protected β-cells from glucolipotoxicity while maintaining β-cell identity. This study may thus not only provide the basis for the development of a unique class of compounds for the treatment of Type 2 Diabetes but also showcases an alternative 'molecular glue' approach for achieving small molecule control of notoriously difficult to target TFs.

Unravelling the interplay between ER stress, UPR and the cGAS-STING pathway: Implications for osteoarthritis pathogenesis and treatment strategy

Osteoarthritis (OA) is a debilitating chronic degenerative disease affecting the whole joint organ leading to pain and disability. Cellular stress and injuries trigger inflammation and the onset of pathophysiological changes ensue after irreparable damage and inability to resolve inflammation, impeding the completion of the healing process. Extracellular matrix (ECM) degradation leads to dysregulated joint tissue metabolism. The reparative effort induces the proliferation of hypertrophic chondrocytes and matrix protein synthesis. Aberrant protein synthesis leads to endoplasmic reticulum (ER) stress and chondrocyte apoptosis with consequent cartilage matrix loss. These events in a vicious cycle perpetuate inflammation, hindering the restoration of normal tissue homeostasis. Recent evidence suggests that inflammatory responses and chondrocyte apoptosis could be caused by the activation of the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) signalling axis in response to DNA damage. It has been reported that there is a crosstalk between ER stress and cGAS-STING signalling in cellular senescence and other diseases. Based on recent evidence, this review discusses the role of ER stress, Unfolded Protein Response (UPR) and cGAS-STING pathway in mediating inflammatory responses in OA.

The regulatory mechanism of natural polysaccharides in type 2 diabetes mellitus treatment

Diabetes is a complex, multifactorial disease that is caused by a pathological combination of insulin resistance and pancreatic islet dysfunction. Polysaccharides are extensively dispersed in nature and have a very complicated structure with various biological properties. Natural polysaccharides have potentially extraordinary beneficial health effects on managing metabolic diseases such as diabetes, obesity and cardiovascular disease. Thus, a systematic review of the latest research into and possible regulatory mechanisms of natural polysaccharides for type 2 diabetes mellitus treatment is of great significance for a better understanding of their pharmaceutical value. We discuss the regulatory mechanisms of natural polysaccharides for the treatment of diabetes, and especially their role in reshaping dysfunctional gut microbiota. Natural polysaccharides could be developed as new and safe antidiabetic drugs, and detailed mechanistic studies could further clarify the molecular targets of polysaccharides in the treatment of diabetes.

The effects of antihypertensive drugs on glucose metabolism

Abnormal glucose metabolism is a common disease of the endocrine system. The effects of drugs on glucose metabolism have been reported frequently in recent years, and since abnormal glucose metabolism increases the risk of microvascular and macrovascular complications, metabolic disorders, and infection, clinicians need to pay close attention to these effects. A variety of common drugs can affect glucose metabolism and have different mechanisms of action. Hypertension is a common chronic cardiovascular disease that requires long-term medication. Studies have shown that various antihypertensive drugs also have an impact on glucose metabolism. Among them, α-receptor blockers, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and calcium channel blockers can improve insulin resistance, while β-receptor blockers, thiazides and loop diuretics can impair glucose metabolism. The aim of this review was to discuss the mechanisms underlying the effects of various antihypertensive drugs on glucose metabolism in order to provide reference information for rational clinical drug use.

Combination therapy enhances efficacy and overcomes toxicity of metal-based anti-diabetic agent

BACKGROUND AND PURPOSE

Metal-based therapeutic agents are limited by the required concentration of metal-based agents. Hereby, we determined if combination with 17β-oestradiol (E2) could reduce such levels and the therapy still be effective in type 2 diabetes mellitus (T2DM).

EXPERIMENTAL APPROACH

The metal-based agent (vanadyl acetylacetonate [VAC])- 17β-oestradiol (E2) combination is administered using the membrane-permeable graphene quantum dots (GQD), the vehicle, to form the active GQD-E2-VAC complexes, which was characterized by fluorescence spectra, infrared spectra and X-ray photoelectron spectroscopy. In db/db type 2 diabetic mice, the anti-diabetic effects of GQD-E2-VAC complexes were evaluated using blood glucose levels, oral glucose tolerance test (OGTT), serum insulin levels, homeostasis model assessment (homeostasis model assessment of insulin resistance [HOMA-IR] and homeostasis model assessment of β-cell function [HOMA-β]), histochemical assays and western blot.

KEY RESULTS

In diabetic mice, GQD-E2-VAC complex had comprehensive anti-diabetic effects, including control of hyperglycaemia, improved insulin sensitivity, correction of hyperinsulinaemia and prevention of β-cell loss. Co-regulation of thioredoxin interacting protein (TXNIP) activation by the combination of metal complex and 17β-oestradiol contributed to the enhanced anti-diabetic effects. Furthermore, a potent mitochondrial protective antioxidant, coniferaldehyde, significantly potentiates the protective effects of GQD-E2-VAC complexes.

CONCLUSION AND IMPLICATIONS

A metal complex-E2 combinatorial approach achieved simultaneously the protection of β cells and insulin enhancement at an unprecedented low dose, similar to the daily intake of dietary metals in vitamin supplements. This study demonstrates the positive effects of combination and multi-modal therapies towards type 2 diabetes treatment.

The endoplasmic reticulum protein HSPA5/BiP is essential for decidual transformation of human endometrial stromal cells

Decidualization denotes the process of inflammatory reprogramming of endometrial stromal cells (EnSC) into specialized decidual cells (DC). During this process, EnSC are subjected to endoplasmic reticulum (ER) stress as well as acute cellular senescence. Both processes contribute to the proinflammatory mid-luteal implantation window and their dysregulation has been implicated in reproductive failure. Here, we evaluated the link between ER stress, decidual differentiation and senescence. In-silico analysis identified HSPA5 gene, codifying the ER chaperone BiP, as a potentially critical regulator of cell fate divergence of decidualizing EnSC into anti-inflammatory DC and pro-inflammatory senescent decidual cells (snDC). Knockdown of HSPA5 in primary EnSC resulted both in decreased expression of DC marker genes and attenuated induction of senescence associated β-galactosidase activity, a marker of snDC. Stalling of the decidual reaction upon HSPA5 knockdown was apparent at 8 days of differentiation and was preceded by the upregulation of ER stress associated proteins IRE1α and PERK. Further, HSPA5 knockdown impaired colony-forming unit activity of primary EnSC, indicative of loss of cellular plasticity. Together, our results point to a key role for HSPA5/BiP in decidual transformation of EnSCs and highlight the importance of constraining ER stress levels during this process.

Recent progress in modeling and treating diabetes using stem cell-derived islets

Stem cell-derived islets (SC-islets) offer the potential to be an unlimited source of cells for disease modeling and the treatment of diabetes. SC-islets can be genetically modified, treated with chemical compounds, or differentiated from patient derived stem cells to model diabetes. These models provide insights into disease pathogenesis and vulnerabilities that may be targeted to provide treatment. SC-islets themselves are also being investigated as a cell therapy for diabetes. However, the transplantation process is imperfect; side effects from immunosuppressant use have reduced SC-islet therapeutic potential. Alternative methods to this include encapsulation, use of immunomodulating molecules, and genetic modification of SC-islets. This review covers recent advances using SC-islets to understand different diabetes pathologies and as a cell therapy.

A novel class of oral, non-immunosuppressive, beta cell-targeting, TXNIP-inhibiting T1D drugs is emerging

Diabetes treatment options have improved dramatically over the last 100 years, however, close to 2 million individuals in the U.S. alone live with type 1 diabetes (T1D) and are still dependent on multiple daily insulin injections and/or continuous insulin infusion with a pump to stay alive and no oral medications are available. After decades of focusing on immunosuppressive/immunomodulatory approaches for T1D, it has now become apparent that at least after disease onset, this by itself may not be sufficient, and in order to be effective, therapies need to also address beta cell health. This Perspective article discusses the emergence of such a beta cell-targeting, novel class of oral T1D drugs targeting thioredoxin-interacting protein (TXNIP) and some very recent advances in this field that start to address this unmet medical need. It thereby focuses on repurposing of the antihypertensive drug, verapamil found to non-specifically inhibit TXNIP and on TIX100, a new chemical entity specifically developed as an oral anti-diabetic drug to inhibit TXNIP. Both have shown striking anti-diabetic effects in preclinical studies. Verapamil has also proven to be beneficial in adults and children with recent onset T1D, while TIX100 has just been cleared by the U.S. Food and Drug Administration (FDA) to proceed to clinical trials. Taken together, we propose that such non-immunosuppressive, adjunctive therapies to insulin, alone or in combination with immune modulatory approaches, are critical in order to achieve effective and durable disease-modifying treatments for T1D.

Exploring the correlation between innate immune activation of inflammasome and regulation of pyroptosis after intracerebral hemorrhage: From mechanism to treatment

Stroke has emerged as the primary cause of disability and death globally in recent years. Intracerebral hemorrhage (ICH), a particularly severe kind of stroke, is occurring in an increasing number of people. The two main clinical treatments for ICH now in use are conservative pharmaceutical therapy and surgical intervention, both of which have risks and drawbacks. Consequently, it is crucial to look into the pathophysiology of ICH and consider cutting-edge therapeutic approaches. Recent research has revealed that pyroptosis is a newly identified type of cell death distinguished by the break of the cell membrane and the discharge of pro-inflammatory substances through different routes. Following ICH, glial cells experience pyroptosis, which worsens neuroinflammation. Hence, the onset and progression of ICH are strongly linked to pyroptosis, which is facilitated by different inflammasomes. It is essential to conduct a comprehensive investigation of ICH damage processes and uncover new targets for treatment. The impact and function of pyroptosis in ICH, as well as the activation and regulation of inflammasomes and their mediated pyroptosis pathways will be fully discussed in this review.

Inducers and Inhibitors of Pyroptotic Death of Granulosa Cells in Models of Premature Ovarian Insufficiency and Polycystic Ovary Syndrome

Granulosa cells (GCs), the largest cell population and primary source of steroid hormones in the ovary, are the important somatic ovarian components. They have critical roles in folliculogenesis by supporting oocyte, facilitating its growth, and providing a microenvironment suitable for follicular development and oocyte maturation, thus having essential functions in maintaining female fertility and in reproductive health in general. Pyroptotic death of GCs and associated inflammation have been implicated in the pathogenesis of several reproductive disorders in females including Premature Ovarian Insufficiency (POI) and Polycystic Ovary Syndrome (PCOS). Here, I reviewed factors, either intrinsic or extrinsic, that induce or inhibit pyroptosis in GCs in various models of these disorders, both in vitro and in vivo, and also covered associated molecular mechanisms. Most of these studied factors influence NLRP3 inflammasome- and GSDMD (Gasdermin D)-mediated pyroptosis in GCs, compared to other inflammasomes and gasdermins (GSDMs). I conclude that a more complete mechanistic understanding of these factors in terms of GC pyroptosis is required to be able to develop novel strategies targeting inflammatory cell death in the ovary.

Mechanistic and therapeutic role of NLRP3 inflammasome in the pathogenesis of Alzheimer's disease

Alzheimer's disease (AD), a progressive neurodegenerative disorder, has emerged as the most common form of dementia in the elderly. Several pathological hallmarks have been identified, including neuroinflammation. A comprehensive insight into the underlying mechanisms that can fuel the development of novel therapeutic approaches is necessary because of the alarmingly rapid increase in the frequency of incidence. Recently, NLRP3 inflammasome was identified as a critical mediator of neuroinflammation. Activation of nucleotide-binding domain (NOD)-like receptor protein 3 (NLRP3) inflammasome by amyloid, neurofibrillary tangles, impaired autophagy and endoplasmic reticulum stress, triggers the release of pro-inflammatory cytokines such as IL-1β and IL-18. Subsequently, these cytokines can promote neurodegeneration and cognitive impairment. It is well established that genetic or pharmacological ablation of NLRP3 alleviates AD-related pathological features in in vitro and in vivo models. Therefore, several synthetic and natural compounds have been identified that exhibit the potential to inhibit NLRP3 inflammasome and alleviate AD-associated pathology. The current review article will highlight the various mechanisms by which activation of NLRP3 inflammation occurs during Alzheimer's disease, and how it influences neuroinflammation, neurodegeneration and cognitive impairment. Moreover, we will summarise the different small molecules that possess the potential to inhibit NLRP3 and can pave the path for developing novel therapeutic interventions for AD.

Silencing of TXNIP attenuates oxidative stress injury in HEI-OC1 by inhibiting the activation of NLRP3 and NF-κB

Sensorineural hearing loss (SNHL) is the most common type of hearing loss worldwide. The primary mechanism is oxidative injury to the cochlea as a result of oxidative stress. Therefore, exploring antioxidant strategies is particularly important in addressing SNHL.Thioredoxin-interacting protein (TXNIP) is an upstream target of oxidative stress-induced damage, and the NOD-like receptor protein 3 (NLRP3) and NF-κB pathways may be the main downstream molecular pathways, but this has not been reported in SNHL. Therefore, we investigated the molecular mechanism and role of TXNIP in oxidative stress injury induced by H2O2 in the HEI-OC1 auditory cells. To induce oxidative stress, HEI-OC1 cells were treated with H2O2. The TXNIP expression was measured by western blotting and Immunofluorescence. Intracellular TXNIP was knocked down using small interfering RNAs (siRNAs). Cell viability was measured by CCK8, total intracellular reactive oxygen species (ROS) by DCFH-DA, mitochondrial ROS by Mito-SOX, NLRP3, pro-caspase-1, total p65 NF-κB, and phospho-p65 NF-κB expression were measured by western blotting. Statistical analyses were performed using one-way analysis of variance, and p < 0.05 was considered statistically significant. We found that H2O2 treatment induced oxidative stress injury in HEI-OC1 cells, as evidenced by decreased cell viability and increased total intracellular and mitochondrial ROS levels (p < 0.05). TXNIP expression was elevated, and NLRP3 and NF-κB were activated (p < 0.05). Moreover, siRNA-TXINIP co-treatment reversed these changes and protected HEI-OC1 cells from oxidative stress (p < 0.05). We concluded that H2O2-induced oxidative stress in HEI-OC1 cells was alleviated by TXNIP inhibition. The finding may provide new insight into the prevention and treatment of SNHL.

Spotlight on endoplasmic reticulum stress in acute kidney injury: A bibliometric analysis and visualization from 1997 to 2024

BACKGROUND

Endoplasmic reticulum (ER) stress, a protective stress response of body and play important role in maintain ER stability. Acute kidney injury (AKI) is a severe syndrome, and the molecular mechanisms of AKI has not been fully elucidated. With an increasing understanding of ER stress, ER stress has been investigated and considered a potential and novel therapeutic target in AKI. This study aims to employ a bibliometric approach to analyze research trends and focal points in ER stress associated with AKI over 3 decades.

METHODS

Data were retrieved from the Web of Science Core Collection on April 15, 2024. CiteSpace and VOSviewer bibliometric software were mainly used to measure bibliometrics and analyze knowledge graphs to predict the latest research trends in the field.

RESULTS

There were 452 "ER stress in AKI" articles in the Web of Science Core Collection. According to the report, China and the United States were the leading research drivers in this field. Central South University was the most active academic institution, contributing the most documents. In this field, Dong Zheng was the most prolific author. The American Journal of Physiology-Renal Physiology was the journal with the most records among all journals. The keywords "NLRP3 inflammasome," "redox signaling," and novel forms of cell death such as "ferroptosis" may represent current research trends and directions.

CONCLUSION

The bibliometric analysis comprehensively examines the trends and hotspots on "ER stress and AKI." Studies on AKI related to stress in the ER are still in their infancy. Research should focus on understanding the relationship between ER stress and inflammasome, redox signal pathways and new forms of cell death such as ferroptosis.

Beyond insulin: Unraveling the complex interplay of ER stress, oxidative damage, and CFTR modulation in CFRD

CF-related diabetes (CFRD) is a prevalent comorbidity in people with Cystic Fibrosis (CF), significantly impacting morbidity and mortality rates. This review article critically evaluates the current understanding of CFRD molecular mechanisms, including the role of CFTR protein, oxidative stress, unfolded protein response (UPR) and intracellular communication. CFRD manifests from a complex interplay between exocrine pancreatic damage and intrinsic endocrine dysfunction, further complicated by the deleterious effects of misfolded CFTR protein on insulin secretion and action. Studies indicate that ER stress and subsequent UPR activation play critical roles in both exocrine and endocrine pancreatic cell dysfunction, contributing to β-cell loss and insulin insufficiency. Additionally, oxidative stress and altered calcium flux, exacerbated by CFTR dysfunction, impair β-cell survival and function, highlighting the significance of antioxidant pathways in CFRD pathogenesis. Emerging evidence underscores the importance of exosomal microRNAs (miRNAs) in mediating inflammatory and stress responses, offering novel insights into CFRD's molecular landscape. Despite insulin therapy remaining the cornerstone of CFRD management, the variability in response to CFTR modulators underscores the need for personalized treatment approaches. The review advocates for further research into non-CFTR therapeutic targets, emphasizing the need to address the multifaceted pathophysiology of CFRD. Understanding the intricate mechanisms underlying CFRD will pave the way for innovative treatments, moving beyond insulin therapy to target the disease's root causes and improve the quality of life for individuals with CF.

Multi-regulatory potency of USP1 on inflammasome components promotes pyroptosis in thyroid follicular cells and contributes to the progression of Hashimoto's thyroiditis

BACKGROUND

Inflammatory diseases are often initiated by the activation of inflammasomes triggered by pathogen-associated molecular patterns (PAMPs) and endogenous damage-associated molecular patterns (DAMPs), which mediate pyroptosis. Although pyroptosis resulting from aberrant inflammasome triggering in thyroid follicular cells (TFCs) has been observed in Hashimoto's thyroiditis (HT) patients, the underlying mechanisms remain largely unknown. Given the extensive involvement of protein ubiquitination and deubiquitination in inflammatory diseases, we aimed to investigate how deubiquitinating enzymes regulate thyroid follicular cell pyroptosis and HT pathogenesis.

METHODS

Our study specifically investigated the role of Ubiquitin-specific peptidase 1 (USP1), a deubiquitinase (DUB), in regulating the inflammasome components NLRP3 and AIM2, which are crucial in pyroptosis. We conducted a series of experiments to elucidate the function of USP1 in promoting pyroptosis associated with inflammasomes and the progression of HT. These experiments involved techniques such as USP1 knockdown or inhibition, measurement of key pyroptosis indicators including caspase-1, caspase-1 p20, and GSDMD-N, and examination of the effects of USP1 abrogation on HT using a mouse model. Furthermore, we explored the impact of USP1 on NLRP3 transcription and its potential interaction with p65 nuclear transportation.

RESULTS

Our findings provide compelling evidence indicating that USP1 plays a pivotal role in promoting inflammasome-mediated pyroptosis and HT progression by stabilizing NLRP3 and AIM2 through deubiquitination. Furthermore, we discovered that USP1 modulates the transcription of NLRP3 by facilitating p65 nuclear transportation. Knockdown or inhibition of USP1 resulted in weakened cell pyroptosis, as evidenced by reduced levels of caspase-1 p20 and GSDMD-N, which could be restored upon AIM2 overexpression. Remarkably, USP1 abrogation significantly ameliorated HT in the mice model, likely to that treating mice with pyroptosis inhibitors VX-765 and disulfiram.

CONCLUSIONS

Our study highlights a regulatory mechanism of USP1 on inflammasome activation and pyroptosis in TFCs during HT pathogenesis. These findings expand our understanding of HT and suggest that inhibiting USP1 may be a potential treatment strategy for managing HT.

Luteolin, apigenin, and chrysin inhibit lipotoxicity-induced NLRP3 inflammasome activation and autophagy damage in macrophages by suppressing endoplasmic reticulum stress

Lipotoxicity leads to numerous metabolic disorders such as nonalcoholic steatohepatitis. Luteolin, apigenin, and chrysin are three flavones with known antioxidant and anti-inflammatory properties, but whether they inhibit lipotoxicity-mediated NLRP3 inflammasome activation was unclear. To address this question, we used J774A.1 macrophages and Kupffer cells stimulated with 100 μM palmitate (PA) in the presence or absence of 20 μM of each flavone. PA increased p-PERK, p-IRE1α, p-JNK1/2, CHOP, and TXNIP as well as p62 and LC3-II expression and induced autophagic flux damage. Caspase-1 activation and IL-1β release were also noted after 24 h of exposure to PA. In the presence of the PERK inhibitor GSK2656157, PA-induced CHOP and TXNIP expression and caspase-1 activation were mitigated. Compared with PA treatment alone, Bcl-2 coupled to beclin-1 was elevated and autophagy was reversed by the JNK inhibitor SP600125. With luteolin, apigenin, and chrysin treatment, PA-induced ROS production, ER stress, TXNIP expression, autophagic flux damage, and apoptosis were ameliorated. Moreover, TXNIP binding to NLRP3 and IL-1β release in response to LPS/PA challenge were reduced. These results suggest that luteolin, apigenin, and chrysin protect hepatic macrophages against PA-induced NLRP3 inflammasome activation and autophagy damage by attenuating endoplasmic reticulum stress.

Emerging insights into the role of NLRP3 inflammasome and endoplasmic reticulum stress in renal diseases

NLRP3 inflammasome is a key component of the innate immune system, mediating the activation of caspase-1, and the maturity and secretion of the pro-inflammatory cytokine interleukin (IL)-1beta (IL-1β) and IL-18 to cope with microbial infections and cell injury. The NLRP3 inflammasome is activated by various endogenous danger signals, microorganisms and environmental stimuli, including urate, extracellular adenosine triphosphate (ATP) and cholesterol crystals. Increasing evidence indicates that the abnormal activation of NLRP3 is involved in multiple diseases including renal diseases. Hence, clarifying the mechanism of action of NLRP3 inflammasome in different diseases can help prevent and treat various diseases. Endoplasmic reticulum (ER) is an important organelle which participates in cell homeostasis maintenance and protein quality control. The unfolded protein response (UPR) and ER stress are caused by the excessive accumulation of unfolded or misfolded proteins in ER to recover ER homeostasis. Many factors can cause ER stress, including inflammation, hypoxia, environmental toxins, viral infections, glucose deficiency, changes in Ca2+ level and oxidative stress. The dysfunction of ER stress participates in multiple diseases, such as renal diseases. Many previous studies have shown that NLRP3 inflammasome and ER stress play an important role in renal diseases. However, the relevant mechanisms are not yet fully clear. Herein, we focus on the current understanding of the role and mechanism of ER stress and NLRP3 inflammasome in renal diseases, hoping to provide theoretical references for future related researches.

Recent advances in anti-inflammation via AMPK activation

Inflammation is a complex physiological phenomenon, which is the body's defensive response, but abnormal inflammation can have adverse effects, and many diseases are related to the inflammatory response. AMPK, as a key sensor of cellular energy status, plays a crucial role in regulating cellular energy homeostasis and glycolipid metabolism. In recent years, the anti-inflammation effect of AMPK and related signalling cascade has begun to enter everyone's field of vision - not least the impact on metabolic diseases. A great number of studies have shown that anti-inflammatory drugs work through AMPK and related pathways. Herein, this article summarises recent advances in compounds that show anti-inflammatory effects by activating AMPK and attempts to comment on them.

Navigating the landscape of the unfolded protein response in CD8+ T cells

Endoplasmic reticulum stress occurs due to large amounts of misfolded proteins, hypoxia, nutrient deprivation, and more. The unfolded protein is a complex intracellular signaling network designed to operate under this stress. Composed of three individual arms, inositol-requiring enzyme 1, protein kinase RNA-like ER kinase, and activating transcription factor-6, the unfolded protein response looks to resolve stress and return to proteostasis. The CD8+ T cell is a critical cell type for the adaptive immune system. The unfolded protein response has been shown to have a wide-ranging spectrum of effects on CD8+ T cells. CD8+ T cells undergo cellular stress during activation and due to environmental insults. However, the magnitude of the effects this response has on CD8+ T cells is still understudied. Thus, studying these pathways is important to unraveling the inner machinations of these powerful cells. In this review, we will highlight the recent literature in this field, summarize the three pathways of the unfolded protein response, and discuss their roles in CD8+ T cell biology and functionality.

Visit to visit transition in TXNIP gene methylation and the risk of type 2 diabetes mellitus: a nested case-control study

Our study aimed to investigate the association between the transition of the TXNIP gene methylation level and the risk of incident type 2 diabetes mellitus (T2DM). This study included 263 incident cases of T2DM and 263 matched non-T2DM participants. According to the methylation levels of five loci (CpG1-5; chr1:145441102-145442001) on the TXNIP gene, the participants were classified into four transition groups: maintained low, low to high, high to low, and maintained high methylation levels. Compared with individuals whose methylation level of CpG2-5 at the TXNIP gene was maintained low, individuals with maintained high methylation levels showed a 61-87% reduction in T2DM risk (66% for CpG2 [OR: 0.34, 95% CI: 0.14, 0.80]; 77% for CpG3 [OR: 0.23, 95% CI: 0.07, 0.78]; 87% for CpG4 [OR: 0.13, 95% CI: 0.03, 0.56]; and 61% for CpG5 [OR: 0.39, 95% CI: 0.16, 0.92]). Maintained high methylation levels of four loci of the TXNIP gene are associated with a reduction of T2DM incident risk in the current study. Our study suggests that preserving hypermethylation levels of the TXNIP gene may hold promise as a potential preventive measure against the onset of T2DM.

A metabolic redox relay supports ER proinsulin export in pancreatic islet β cells

ER stress and proinsulin misfolding are heralded as contributing factors to β cell dysfunction in type 2 diabetes, yet how ER function becomes compromised is not well understood. Recent data identify altered ER redox homeostasis as a critical mechanism that contributes to insulin granule loss in diabetes. Hyperoxidation of the ER delays proinsulin export and limits the proinsulin supply available for insulin granule formation. In this report, we identified glucose metabolism as a critical determinant in the redox homeostasis of the ER. Using multiple β cell models, we showed that loss of mitochondrial function or inhibition of cellular metabolism elicited ER hyperoxidation and delayed ER proinsulin export. Our data further demonstrated that β cell ER redox homeostasis was supported by the metabolic supply of reductive redox donors. We showed that limiting NADPH and thioredoxin flux delayed ER proinsulin export, whereas thioredoxin-interacting protein suppression restored ER redox and proinsulin trafficking. Taken together, we propose that β cell ER redox homeostasis is buffered by cellular redox donor cycles, which are maintained through active glucose metabolism.

Redox regulation of UPR signalling and mitochondrial ER contact sites

Mitochondria and the endoplasmic reticulum (ER) have a synergistic relationship and are key regulatory hubs in maintaining cell homeostasis. Communication between these organelles is mediated by mitochondria ER contact sites (MERCS), allowing the exchange of material and information, modulating calcium homeostasis, redox signalling, lipid transfer and the regulation of mitochondrial dynamics. MERCS are dynamic structures that allow cells to respond to changes in the intracellular environment under normal homeostatic conditions, while their assembly/disassembly are affected by pathophysiological conditions such as ageing and disease. Disruption of protein folding in the ER lumen can activate the Unfolded Protein Response (UPR), promoting the remodelling of ER membranes and MERCS formation. The UPR stress receptor kinases PERK and IRE1, are located at or close to MERCS. UPR signalling can be adaptive or maladaptive, depending on whether the disruption in protein folding or ER stress is transient or sustained. Adaptive UPR signalling via MERCS can increase mitochondrial calcium import, metabolism and dynamics, while maladaptive UPR signalling can result in excessive calcium import and activation of apoptotic pathways. Targeting UPR signalling and the assembly of MERCS is an attractive therapeutic approach for a range of age-related conditions such as neurodegeneration and sarcopenia. This review highlights the emerging evidence related to the role of redox mediated UPR activation in orchestrating inter-organelle communication between the ER and mitochondria, and ultimately the determination of cell function and fate.