Hydroxychloroquine attenuates renal ischemia/reperfusion injury by inhibiting cathepsin mediated NLRP3 inflammasome activation

miR-208a-3p regulated by circUQCRC2 suppresses ischemia/reperfusion-induced acute kidney injury by inhibiting CELF2-mediated tubular epithelial cell apoptosis, inflammation and ferroptosis

ABSTRACT

Background : Acute kidney injury (AKI) is a prevalent clinical syndrome with persistent kidney dysfunction. Renal ischemia/reperfusion (I/R) injury is a major cause of AKI. miR-208a-3p overexpression attenuated myocardial I/R injury. This study aims to investigate the role and mechanism of miR-208a-3p in I/R-induced AKI. Methods : AKI models were established using hypoxia/reoxygenation (H/R)-exposed tubule epithelial cell HK-2 and I/R-induced mice. The function and mechanism of miR-208a-3p were investigated by gain- or loss-of-function methods using real-time PCR, CCK-8, flow cytometry, ELISA, western blot, hematoxylin-eosin staining, terminal deoxynucleotidyl transferase dUTP nick end labeling assay, detection of Fe 2+ , reactive oxygen species, blood urea nitrogen and creatinine, and luciferase reporter assay. Results : miR-208a-3p expression was suppressed, while the expression of CELF2 and circular RNA ubiquinol-cytochrome c reductase core protein 2 (circUQCRC2) was increased in both AKI models. miR-208a-3p upregulation or circUQCRC2 silencing increased the viability, decreased the levels of proinflammatory cytokines (TNF-α, IL-1β, and IL-6), reduced apoptosis and contents of Fe 2+ and reactive oxygen species, elevated expression of GPX4 and SLC7A11, and reduced ACSL4 expression in H/R-stimulated HK-2 cells. In addition, miR-208a-3p improved kidney function by alleviating renal injury, apoptosis, inflammation, and ferroptosis in AKI mouse model. CELF2 was a target gene of miR-208a-3p, which was negatively modulated by circUQCRC2. Overexpression of CELF2 blocked the function of miR-208a-3p upregulation or circUQCRC2 silencing on H/R-treated HK-2 cells. Moreover, the effects of circUQCRC2 downregulation on H/R-injured cells were also reversed by miR-208a-3p inhibitor. Conclusions : miR-208a-3p regulated by circUQCRC2 could attenuate I/R-induced AKI by inhibiting CELF2-mediated tubular epithelial cell apoptosis, inflammation and ferroptosis. This study provides potential therapeutic targets for I/R-induced AKI.

YOD1 protects against MRSA sepsis-induced DIC through Lys33-linked deubiquitination of NLRP3

Disseminated intravascular coagulation (DIC) is considered to be the most common and lethal complication of sepsis. NLR-family pyrin domain-containing-3 (NLRP3) inflammasome plays an important role in host defense against microbial pathogens, and its deregulation may cause coagulation cascade and should be strictly managed. Here, we identified the deubiquitinase YOD1, which played a vital role in regulating coagulation in a NLRP3 inflammasome-dependent manner in sepsis induced by methicillin-resistant Staphylococcus aureus (MRSA). YOD1 interacted with NLRP3 to remove K33-linked ubiquitination of NLRP3 based on its deubiquitinating enzyme activity and specifically inhibited expression of NLRP3 as well as activation of NLRP3 inflammasome. Deficiency of YOD1 expression enhanced NLRP3 inflammasome activation and coagulation both in vitro and in vivo. In addition, pharmacological inhibition of the NLRP3 effectively improved coagulation and alleviated organ injury in Yod1-/- mice infected with MRSA. Thus, our study reported that YOD1 is a key regulator of coagulation during MRSA infection, and provided YOD1 as a potential therapeutic target for the treatment of NLRP3 inflammasome-related diseases, especially MRSA sepsis-induced DIC.

Specific NOX4 Inhibition Preserves Mitochondrial Function and Dampens Kidney Dysfunction Following Ischemia-Reperfusion-Induced Kidney Injury

Background: Acute kidney injury (AKI) is a sudden episode of kidney failure which is frequently observed at intensive care units and related to high morbidity/mortality. Although AKI can have many different causes, ischemia-reperfusion (IR) injury is the main cause of AKI. Mechanistically, NADPH oxidases (NOXs) are involved in the pathophysiology contributing to oxidative stress following IR. Previous reports have indicated that knockout of NOX4 may offer protection in cardiac and brain IR, but there is currently less knowledge about how this could be exploited therapeutically and whether this could have significant protection in IR-induced AKI. Aim: To investigate the hypothesis that a novel and specific NOX4 inhibitor (GLX7013114) may have therapeutic potential on kidney and mitochondrial function in a mouse model of IR-induced AKI. Methods: Kidneys of male C57BL/6J mice were clamped for 20 min, and the NOX4 inhibitor (GLX7013114) was administered via osmotic minipump during reperfusion. Following 3 days of reperfusion, kidney function (i.e., glomerular filtration rate, GFR) was calculated from FITC-inulin clearance and mitochondrial function was assessed by high-resolution respirometry. Renal histopathological evaluations (i.e., hematoxylin-eosin) and TUNEL staining were performed for apoptotic evaluation. Results: NOX4 inhibition during reperfusion significantly improved kidney function, as evidenced by a better-maintained GFR (p < 0.05) and lower levels of blood urea nitrogen (p < 0.05) compared to untreated IR animals. Moreover, IR caused significant tubular injuries that were attenuated by simultaneous NOX4 inhibition (p < 0.01). In addition, the level of renal apoptosis was significantly reduced in IR animals with NOX4 inhibition (p < 0.05). These favorable effects of the NOX4 inhibitor were accompanied by enhanced Nrf2 Ser40 phosphorylation and conserved mitochondrial function, as evidenced by the better-preserved activity of all mitochondrial complexes. Conclusion: Specific NOX4 inhibition, at the time of reperfusion, significantly preserves mitochondrial and kidney function. These novel findings may have clinical implications for future treatments aimed at preventing AKI and related adverse events, especially in high-risk hospitalized patients.

Pioglitazone ameliorates ischemia/reperfusion-induced acute kidney injury via oxidative stress attenuation and NLRP3 inflammasome

Acute kidney injury (AKI) induced by renal ischemia/reperfusion injury (IRI) is a severe clinical condition. ROS accumulation, antioxidant pathways deficiency, and inflammation are involved in IRI. Pioglitazone (Pio) exerts anti-inflammatory and antioxidant effects. The aim of this study was to explore the protective effects of pioglitazone against IRI-induced AKI. Pathogen-free Sprague-Dawley (SD) rats were arbitrarily divided into four groups: Sham operation group Control (CON) group, CON + Pio group, I/R + Saline group, and I/R + Pio group. In addition, HK-2 cells were subjected to hypoxia and reoxygenation to develop an H/R model for investigation of the protective mechanism of Pio. Pretreatment with pioglitazone in the model rats reduced urea nitrogen and creatinine levels, histopathological scores, and cytotoxicity after IRI. Pioglitazone treatment significantly attenuated renal cell apoptosis, decreased cytotoxicity, increased Bcl-2 expression, and downregulated Bax expression. Besides, the levels of ROS and inflammatory factors, including NLRP3, ASC, pro-IL-1β, pro-caspase-1, cleaved-caspase-1, TNF-α, IL-6, and IL-1β, in I/R rats and H/R cells were normalized by the pioglitazone treatment. Pioglitazone improved IRI-induced AKI by attenuating oxidative stress and NLRP3 inflammasome activation. Therefore, pioglitazone has the potential to serve as a novel agent for renal IRI treatment and prevention.

Allogeneic bone marrow mesenchymal stem cell-derived exosomes alleviate human hypoxic AKI-on-a-Chip within a tight treatment window

BACKGROUND

Acute hypoxic proximal tubule (PT) injury and subsequent maladaptive repair present high mortality and increased risk of acute kidney injury (AKI) - chronic kidney disease (CKD) transition. Human bone marrow mesenchymal stem cell-derived exosomes (hBMMSC-Exos) as potential cell therapeutics can be translated into clinics if drawbacks on safety and efficacy are clarified. Here, we determined the real-time effective dose and treatment window of allogeneic hBMMSC-Exos, evaluated their performance on the structural and functional integrity of 3D microfluidic acute hypoxic PT injury platform.

METHODS

hBMMSC-Exos were isolated and characterized. Real-time impedance-based cell proliferation analysis (RTCA) determined the effective dose and treatment window for acute hypoxic PT injury. A 2-lane 3D gravity-driven microfluidic platform was set to mimic PT in vitro. ZO-1, acetylated α-tubulin immunolabelling, and permeability index assessed structural; cell proliferation by WST-1 measured functional integrity of PT.

RESULTS

hBMMSC-Exos induced PT proliferation with ED50 of 172,582 µg/ml at the 26th hour. Hypoxia significantly decreased ZO-1, increased permeability index, and decreased cell proliferation rate on 24-48 h in the microfluidic platform. hBMMSC-Exos reinforced polarity by a 1.72-fold increase in ZO-1, restored permeability by 20/45-fold against 20/155 kDa dextran and increased epithelial proliferation 3-fold compared to control.

CONCLUSIONS

The real-time potency assay and 3D gravity-driven microfluidic acute hypoxic PT injury platform precisely demonstrated the therapeutic performance window of allogeneic hBMMSC-Exos on ischemic AKI based on structural and functional cellular data. The novel standardized, non-invasive two-step system validates the cell-based personalized theragnostic tool in a real-time physiological microenvironment prior to safe and efficient clinical usage in nephrology.

The Application of Drugs and Nano-Therapies Targeting Immune Cells in Hypoxic Inflammation

Immune cells are pivotal in the dynamic interplay between hypoxia and inflammation. During hypoxic conditions, HIF-1α, a crucial transcription factor, facilitates the adaptation of immune cells to the hypoxic micro-environment. This adaptation includes regulating immune cell metabolism, significantly impacting inflammation development. Strategies for anti-inflammatory and hypoxic relief have been proposed, aiming to disrupt the hypoxia-inflammation nexus. Research extensively focuses on anti-inflammatory agents and materials that target immune cells. These primarily mitigate hypoxic inflammation by encouraging M2-macrophage polarization, restraining neutrophil proliferation and infiltration, and maintaining Treg/TH17 balance. Additionally, oxygen-releasing nano-materials play a significant role. By alleviating hypoxia and clearing reactive oxygen species (ROS), these nano-materials indirectly influence immune cell functions. This paper delves into the response of immune cells under hypoxic conditions and the resultant effects on inflammation. It provides a comprehensive overview of various therapies targeting specific immune cells for anti-inflammatory purposes and explores nano-materials that either carry or generate oxygen to alleviate anoxic micro-environments.

Sodium sulfite triggered hepatic apoptosis, necroptosis, and pyroptosis by inducing mitochondrial damage in mice and AML-12 cells

Sodium sulfite (SS) is a biological derivative of the air pollutant sulfur dioxide, and is often used as a food and pharmaceutical additive. Improper or excessive SS exposure in liver cell death. The phenomenon of simultaneous regulation of apoptosis, necroptosis, and pyroptosis is defined as PANoptosis. However, the specific types of programmed cell death (PCD) caused by SS and their interconnections remain unclear. In the present study, C57BL/6 mice were orally administered SS for 30 d, consecutively, to establish an in vivo mouse exposure model. AML-12 cells were treated with SS for 24 h to establish an in vitro exposure model. The results showed that SS-induced mitochondrial reactive oxygen species (mtROS) accumulation activated the BAX/Bcl-2/caspase 3 pathway to trigger apoptosis and RIPK1/RIPK3/p-MLKL to trigger necroptosis. Interestingly, ROS-activated p-MLKL perforated not the cell membrane as well as the lysosomal membrane. We determined that p-MLKL mediates lysosomal membrane permeabilization (LMP), resulting in cathepsin B (CTSB) release. Furthermore, knockdown of MLKL, a CTSB inhibitor (CA074-ME) and an NLRP3 inhibitor (MCC950) alleviated SS-induced pyroptosis. In summary, our study showed that SS induced apoptosis and necroptosis though mtROS accumulation, whereas the activation of p-MLKL mediated NLRP3-dependent pyroptosis by causing CTSB leakage through LMP. This study comprehensively explored the mechanism unerlying SS-induced PCD and provided an experimental basis for p-MLKL as a potential regulatory protein in PANoptosis.

Fluorofenidone attenuates renal fibrosis by inhibiting lysosomal cathepsin‑mediated NLRP3 inflammasome activation

Currently, no antifibrotic drug in clinical use can effectively treat renal fibrosis. Fluorofenidone (AKFPD), a novel pyridone agent, significantly reduces renal fibrosis by inhibiting the activation of the NOD-like receptor thermal protein domain associated protein 3 (NLRP3) inflammasome; however, the underlying mechanism of this inhibition is not fully understood. The present study aimed to reveal the molecular mechanism underlying the suppression of NLRP3 inflammasome activation by AKFPD. It investigated the effect of AKFPD on NLRP3 activation and lysosomal cathepsins in a unilateral ureteral obstruction (UUO) rat model, and hypoxia/reoxygenation (H/R)-treated HK-2 cells and murine peritoneal-derived macrophages (PDMs) stimulated with lipopolysaccharide (LPS) and ATP. The results confirmed that AKFPD suppressed renal interstitial fibrosis and inflammation by inhibiting NLRP3 inflammasome activation in UUO rat kidney tissues. In addition, AKFPD reduced the production of activated caspase-1 and maturation of IL-1β by suppressing NLRP3 inflammasome activation in H/R-treated HK-2 cells and murine PDMs stimulated with LPS and ATP. AKFPD also decreased the activities of cathepsins B, L and S both in vivo and in vitro. Notably, AKFPD downregulated cathepsin B expression and NLRP3 colocalization in the cytoplasm after lysosomal disruptions. Overall, the results suggested that AKFPD attenuates renal fibrosis by inhibiting lysosomal cathepsin-mediated activation of the NLRP3 inflammasome.

Resveratrol Ameliorates Retinal Ischemia-Reperfusion Injury by Modulating the NLRP3 Inflammasome and Keap1/Nrf2/HO-1 Signaling Pathway

Glaucoma, as an ischemia-reperfusion (I/R) injury disease, leading irreversible blindness through the loss of retinal ganglion cells (RGCs), mediated by various pathways. Resveratrol (Res) is a polyphenolic compound that exerts protective effects against I/R injury in many tissues. This article aimed to expound the underlying mechanisms through which Res protects RGCs and reduces visual dysfunction in vivo. An experimental glaucoma model was created using 6-8-week wild-type male C57BL/6J mice. Res was injected intraperitoneally for 5 days. The mice were then grouped according to the number of days after surgery and whether Res treatment was administered. We applied the Brn3a-labeled immunofluorescence staining and flash electroretinography (ERG) to assess the survival of RGCs and visual function. The expression of components of the NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasome, the interleukin-1-beta (IL-1β), and vital indicators of kelch-like ECH-associated protein 1 (Keap1)/nuclear factor erythroid 2-related factor 2 (Nrf2)/heme-oxygenase 1 (HO-1) pathway at the protein and RNA levels were detected respectively. The survival of RGCs was reduced after surgery compared to controls, whereas Res application rescued RGCs and improved visual dysfunction. In conclusion, our results discovered that Res administration showed neuroprotective effects through inhibition of the NLRP3 inflammasome pathway and activation of Keap1/Nrf2/HO-1 pathway. Thus, we further elucidated the potential of Res in glaucoma therapy.

FGF21 Inhibits Hypoxia/Reoxygenation-induced Renal Tubular Epithelial Cell Injury by Regulating the PPARγ/NF-κB Signaling Pathway

As a predominant trigger of acute kidney injury, renal ischemia-reperfusion injury can cause permanent renal impairment, and the effective therapies are lacking. Fibroblast growth factor 21 (FGF21) plays a critical regulatory role in a variety of biological activities. This study was conducted to explore the functional of FGF21 in renal ischemia-reperfusion injury and to discuss the hidden reaction mechanism. To simulate renal ischemia-reperfusion injury in vitro, HK2 cells were induced by hypoxia/reoxygenation (H/R). The effects of FGF21 on H/R-induced HK2 cell viability were evaluated utilizing cell counting kit-8 (CCK-8). The levels of lactate dehydrogenase (LDH) and inflammatory cytokines in H/R-induced HK2 cells were assessed by means of LDH assay and enzyme-linked immunosorbent assay (ELISA). The levels of oxidative stress markers were appraised with corresponding assay kits and western blot was applied to estimate the expressions of oxidative stress-related proteins. The apoptosis of H/R-induced HK2 cells was assessed by virtue of flow cytometry. The expressions of apoptosis- and PPARγ/NF-κB signaling pathway-related proteins were evaluated with western blot. To discuss the reaction mechanism of PPARγ/NF-κB pathway in H/R-induced HK2 cells, PPARγ inhibitor GW9662 was employed to treat cells and the above experiments were then conducted again. This study found that FGF21 treatment inhibited the inflammatory response, oxidative stress and apoptosis in H/R-induced HK2 cells. Moreover, FGF21 regulated PPARγ/NF-κB signaling pathway and GW9662 partially reversed the impacts of FGF21 on the inflammatory response, oxidative stress and apoptosis in H/R-exposed HK2 cells. Collectively, FGF21 protected against H/R-induced renal tubular epithelial cell injury by regulating the PPARγ/NF-κB signaling pathway.

Toxicity assessment of perovskite nanocomposites: In vivo study

Perovskite solar cells display potential as a renewable energy source because of their high-power conversion efficiency. However, there is limited understanding regarding the potential impact of perovskite on human health and the ecosystem. In this study, two sets of male Wistar albino rats received 35 injections of perovskite composite at a dosage of 0.372 mg/kg body weight. The animals underwent thorough examinations, encompassing morphometric, hematological, biochemical, histological, and behavioral analyses. Liver, kidney, and testis biopsies were processed and examined histologically. Additionally, two groups of mice (perovskite-treated and control mice, each with n = 10) underwent three behavioral tests: the Elevated Zero Maze test, Marble Burying test, and Light-Dark Box test. Perovskite-treated rats displayed a significant increase in levels of aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, triglycerides, cholesterol, creatinine, blood urea nitrogen, white blood cells, and platelets. However, total bilirubin levels decreased, with no significant alteration in albumin values. Furthermore, exposure to perovskite composite resulted in a slight decrease in lactate dehydrogenase and red blood cell count. Histopathological examination revealed hepatic hydropic degeneration, Kupffer cells hypertrophy and hyperplasia, and renal hydropic degeneration, while testicular tissues remained unaffected. Moreover, behavioral changes were observed in perovskite-treated mice, including depression, anxiety, and compulsive burying activity. These findings suggest that exposure to perovskite can lead to significant hematological and biochemical changes, as well as hepatorenal histopathological alterations and behavioral changes. Additionally, chronic exposure to perovskite materials may induce structural and functional alterations in vital organs.

Insights into the time-course cellular effects triggered by iron oxide nanoparticles by combining proteomics with the traditional pharmacology strategy

In recent years, a number of initially approved magnetic iron oxide nanoparticle (IONP)-based nano-medicines have been withdrawn due to the obscure nano-bio effects. Therefore, there is an urgent need to study the cellular effects triggered by IONPs on cells. In this study, we investigate the time-course cellular effects on the response of RAW 264.7 cells caused by Si-IONPs via pharmacological and mass spectrometry-based proteomics techniques. Our results revealed that Si-IONPs were internalized by clathrin-mediated endocytosis within 1 hour, and gradually degraded in endolysosomes over time, which might influence autophagy, oxidative stress, innate immune response, and inflammatory response after 12 hours. Our research provides a necessary assessment of Si-IONPs for further clinical treatment.

Role of NLRP3 Inflammasome in Stroke Pathobiology: Current Therapeutic Avenues and Future Perspective

Neuroinflammation is a key pathophysiological feature of stroke-associated brain injury. A local innate immune response triggers neuroinflammation following a stroke via activating inflammasomes. The nucleotide-binding oligomerization domain leucine-rich repeat and pyrin domain-containing protein 3 (NLRP3) inflammasome has been heavily implicated in stroke pathobiology. Following a stroke, several stimuli have been suggested to trigger the assembly of the NLRP3 inflammasome. Recent studies have advanced the understanding and revealed several new players regulating NLRP3 inflammasome-mediated neuroinflammation. This article discussed recent advancements in NLRP3 assembly and highlighted stroke-induced mitochondrial dysfunction as a major checkpoint to regulating NLRP3 activation. The NLRP3 inflammasome activation leads to caspase-1-dependent maturation and release of IL-1β, IL-18, and gasdermin D. In addition, genetic or pharmacological inhibition of the NLRP3 inflammasome activation and downstream signaling has been shown to attenuate brain infarction and improve the neurological outcome in experimental models of stroke. Several drug-like small molecules targeting the NLRP3 inflammasome are in different phases of development as novel therapeutics for various inflammatory conditions, including stroke. Understanding how these molecules interfere with NLRP3 inflammasome assembly is paramount for their better optimization and/or development of newer NLRP3 inhibitors. In this review, we summarized the assembly of the NLRP3 inflammasome and discussed the recent advances in understanding the upstream regulators of NLRP3 inflammasome-mediated neuroinflammation following stroke. Additionally, we critically examined the role of the NLRP3 inflammasome-mediated signaling in stroke pathophysiology and the development of therapeutic modalities to target the NLRP3 inflammasome-related signaling for stroke treatment.

Cathepsin B aggravates atherosclerosis in ApoE-deficient mice by modulating vascular smooth muscle cell pyroptosis through NF-κB / NLRP3 signaling pathway

Atherosclerosis (AS) is a chronic inflammatory disease involving cell death and inflammatory responses. Pyroptosis, a newly discovered pro-inflammatory programmed cell death process, exacerbates inflammatory responses. However, the roles of cathepsin B (CTSB) in pyroptosis and AS remain unclear. To gain further insight, we fed ApoE-/- mice a high-fat diet to investigate the effects and mechanisms of CTSB overexpression and silencing on AS. We also explored the specific role of CTSB in vascular smooth muscle cells (VSMCs) in vitro. The study revealed that high-fat diet led to the formation of AS plaques, and CTSB was found to increase the AS plaque lesion area. Immunohistochemical and TUNEL/caspase-1 staining revealed the existence of pyroptosis in atherosclerotic plaques, particularly in VSMCs. In vitro studies, including Hoechst 33342/propidium iodide staining, a lactate dehydrogenase (LDH) release assay, detection of protein indicators of pyroptosis, and detection of interleukin-1β (IL-1β) in cell culture medium, demonstrated that oxidized low-density lipoprotein (ox-LDL) induced VSMC pyroptosis. Additionally, CTSB promoted VSMC pyroptosis. Ox-LDL increased the expression of CTSB, which in turn activated the NOD-like receptor protein 3 (NLRP3) inflammasome and promoted NLRP3 expression by facilitating nuclear factor kappa B (NF-κB) p65 nuclear translocation. This effect could be attenuated by the NF-κB inhibitor SN50. Our research found that CTSB not only promotes VSMC pyroptosis by activating the NLRP3 inflammasome, but also increases the expression of NLRP3.

A variety of death modes of neutrophils and their role in the etiology of autoimmune diseases

Neutrophils are important in the context of innate immunity and actively contribute to the progression of diverse autoimmune disorders. Distinct death mechanisms of neutrophils may exhibit specific and pivotal roles in autoimmune diseases and disease pathogenesis through the orchestration of immune homeostasis, the facilitation of autoantibody production, the induction of tissue and organ damage, and the incitement of pathological alterations. In recent years, more studies have provided in-depth examination of various neutrophil death modes, revealing nuances that challenge conventional understanding and underscoring their potential clinical utility in diagnosis and treatment. This review explores the multifaceted processes and characteristics of neutrophil death, with a focus on tailored investigations within various autoimmune diseases. It also highlights the potential interplay between neutrophil death and the landscape of autoimmune disorders. The review encapsulates the pertinent pathways implicated in various neutrophil death mechanisms across diverse autoimmune diseases while also charts possible avenues for future research.

Multiparametric Magnetic Resonance Investigations on Acute and Long-Term Kidney Injury

Acute kidney injury (AKI) is a frequent complication of critical illness and carries a significant risk of short- and long-term mortality. The prediction of the progression of AKI to long-term injury has been difficult for renal disease treatment. Radiologists are keen for the early detection of transition from AKI to long-term kidney injury, which would help in the preventive measures. The lack of established methods for early detection of long-term kidney injury underscores the pressing needs of advanced imaging technology that reveals microscopic tissue alterations during the progression of AKI. Fueled by recent advances in data acquisition and post-processing methods of magnetic resonance imaging (MRI), multiparametric MRI is showing great potential as a diagnostic tool for many kidney diseases. Multiparametric MRI studies offer a precious opportunity for real-time noninvasive monitoring of pathological development and progression of AKI to long-term injury. It provides insight into renal vasculature and function (arterial spin labeling, intravoxel incoherent motion), tissue oxygenation (blood oxygen level-dependent), tissue injury and fibrosis (diffusion tensor imaging, diffusion kurtosis imaging, T1 and T2 mapping, quantitative susceptibility mapping). The multiparametric MRI approach is highly promising but the longitudinal investigation on the transition of AKI to irreversible long-term impairment is largely ignored. Further optimization and implementation of renal MR methods in clinical practice will enhance our comprehension of not only AKI but chronic kidney diseases. Novel imaging biomarkers for microscopic renal tissue alterations could be discovered and benefit the preventative interventions. This review explores recent MRI applications on acute and long-term kidney injury while addressing lingering challenges, with emphasis on the potential value of the development of multiparametric MRI for renal imaging on clinical systems. EVIDENCE LEVEL: 1 TECHNICAL EFFICACY: Stage 2.

Regulation of cellular senescence by innate immunity

During the COVID-19 pandemic, the interplay between the processes of immunity and senescence is drawing more and more intensive attention. SARS-CoV-2 infection induces senescence in lung cells, failure to clear infected cells and increased presence of inflammatory factors could lead to a cytokine storm and acute respiratory disease syndrome (ARDS), which together with aging and age-associated disease lead to 70% of COVID-19-related deaths. Studies on how senescence initiates upon viral infection and how to restrict excessive accumulation of senescent cells to avoid harmful inflammation are crucially important. Senescence can induce innate immune signaling, and innate immunity can engage cell senescence. Here, we mainly review the innate immune pathways, such as cGAS-STING, TLRs, NF-κB, and NLRP3 inflammasome, participating in the senescence process. In these pathways, IFN-I and inflammatory factors play key roles. At the end of the review, we propose the strategies by which we can improve the immune function and reduce inflammation based on these findings.

Lycopene Alleviates Chronic Stress-Induced Hippocampal Microglial Pyroptosis by Inhibiting the Cathepsin B/NLRP3 Signaling Pathway

Lycopene (LYC) exerts a strong neuroprotective and antipyroptotic effects. This study explored the effects and mechanisms of LYC on chronic stress-induced hippocampal microglial damage and depression-like behaviors. The caspase-1 inhibitor VX-765 attenuated chronic restrain stress (CRS)-induced hippocampal microglial pyroptosis and depression-like behaviors. Moreover, the alleviation of CRS-induced hippocampal microglial pyroptosis and depression-like behaviors by LYC was associated with the cathepsin B/NLRP3 pathway. In vitro, the caspase-1 inhibitor Z-YVAD-FMK alleviated pyroptosis in highly aggressively proliferating immortalized (HAPI) cells. Additionally, the alleviation of corticosterone-induced HAPI cell damage and pyroptosis by LYC was associated with the cathepsin B/NLRP3 pathway. Furthermore, the cathepsin B agonist pazopanib promoted HAPI cell pyroptosis, whereas LYC inhibited pazopanib-induced pyroptosis via the cathepsin B/NLRP3 pathway. Similarly, Z-YVAD-FMK inhibited pazopanib-induced HAPI cell pyroptosis. These results suggest that LYC alleviates chronic stress-induced hippocampal microglial pyroptosis via the cathepsin B/NLRP3 pathway inhibition. This study provides a new strategy for treating chronic stress encephalopathy.

4-Octyl itaconate alleviates renal ischemia reperfusion injury by ameliorating endoplasmic reticulum stress via Nrf2 pathway

Renal ischemia-reperfusion injury (IRI) is a common clinical complication of multiple severe diseases. Owing to its high mortality and the lack of effective treatment, renal IRI is still an intractable problem for clinicians. Itaconate, which is a metabolite of cis-aconitate, can exert anti-inflammatory and antioxidant roles in many diseases. As a derivative of itaconate with high cell membrane permeability, 4-octyl itaconate (4-OI) could provide a protective effect for various diseases. However, the role of 4-OI in renal IRI is still unclear. Herein, we examined whether 4-OI afforded kidney protection through attenuating endoplasmic reticulum stress (ERS) via nuclear factor erythroid-2-related factor 2 (Nrf2) pathway. To observe the effects of 4-OI on alleviating renal pathologic injury, improving renal dysfunction, decreasing inflammatory cytokines, and reducing oxidative stress, we utilized C57BL/6J mice with bilateral renal pedicle clamped and HK-2 cells with hypoxia/reoxygenation (H/R) exposure in our study. In addition, through western blot assay, we found 4-OI ameliorated renal IRI-induced ERS, and activated Nrf2 pathway. Moreover, Nrf2-knockout (KO) mice and Nrf2 knockdown HK-2 cells were used to validate the role of Nrf2 signaling pathway in 4-OI-mediated alleviation of ERS caused by renal IRI. We demonstrated that 4-OI relieved renal injury and suppressed ERS in wild-type mice, while the therapeutic role was not shown in Nrf2-KO mice. Similarly, 4-OI could exert cytoprotective effect and inhibit ERS in HK-2 cells after H/R, but not in Nrf2 knockdown cells. Our in vivo and in vitro studies revealed that 4-OI protected renal IRI through attenuating ERS via Nrf2 pathway.

Hydroxychloroquine in nephrology: current status and future directions

Hydroxychloroquine is one of the oldest disease-modifying anti-rheumatic drugs in clinical use. The drug interferes with lysosomal activity and antigen presentation, inhibits autophagy, and decreases transcription of pro-inflammatory cytokines. Owing to its immunomodulatory, anti-inflammatory, anti-thrombotic effect, hydroxychloroquine has been an integral part of therapy for systemic lupus erythematosus and lupus nephritis for several decades. The therapeutic versatility of hydroxychloroquine has led to repurposing it for other clinical conditions, with recent studies showing reduction in proteinuria in IgA nephropathy. Research is also underway to investigate the efficacy of hydroxychloroquine in primary membranous nephropathy, Alport's syndrome, systemic vasculitis, anti-GBM disease, acute kidney injury and for cardiovascular risk reduction in chronic kidney disease. Hydroxychloroquine is well-tolerated, inexpensive, and widely available and therefore, should its indications expand in the future, it would certainly be welcomed. However, clinicians should be aware of the risk of irreversible and progressive retinal toxicity and rarely, cardiomyopathy. Monitoring hydroxychloroquine levels in blood appears to be a promising tool to evaluate compliance, individualize the dose and reduce the risk of retinal toxicity, although this is not yet standard clinical practice. In this review, we discuss the existing knowledge regarding the mechanism of action of hydroxychloroquine, its utility in lupus nephritis and other kidney diseases, the main adverse effects and the evidence gaps that need to be addressed in future research. Created with Biorender.com. HCQ, hydroxychloroquine; GBM, glomerular basement membrane; mDC, myeloid dendritic cell; MHC, major histocompatibility complex; TLR, toll-like receptor.

Early plasma proteomic biomarkers and prediction model of acute respiratory distress syndrome after cardiopulmonary bypass: a prospective nested cohort study

BACKGROUND

Early recognition of the risk of acute respiratory distress syndrome (ARDS) after cardiopulmonary bypass (CPB) may improve clinical outcomes. The main objective of this study was to identify proteomic biomarkers and develop an early prediction model for CPB-ARDS.

METHODS

The authors conducted three prospective nested cohort studies of all consecutive patients undergoing cardiac surgery with CPB at Union Hospital of Tongji Medical College Hospital. Plasma proteomic profiling was performed in ARDS patients and matched controls (Cohort 1, April 2021-July 2021) at multiple timepoints: before CPB (T1), at the end of CPB (T2), and 24 h after CPB (T3). Then, for Cohort 2 (August 2021-July 2022), biomarker expression was measured and verified in the plasma. Furthermore, lung ischemia/reperfusion injury (LIRI) models and sham-operation were established in 50 rats to explore the tissue-level expression of biomarkers identified in the aforementioned clinical cohort. Subsequently, a machine learning-based prediction model incorporating protein and clinical predictors from Cohort 2 for CPB-ARDS was developed and internally validated. Model performance was externally validated on Cohort 3 (January 2023-March 2023).

RESULTS

A total of 709 proteins were identified, with 9, 29, and 35 altered proteins between ARDS cases and controls at T1, T2, and T3, respectively, in Cohort 1. Following quantitative verification of several predictive proteins in Cohort 2, higher levels of thioredoxin domain containing 5 (TXNDC5), cathepsin L (CTSL), and NPC intracellular cholesterol transporter 2 (NPC2) at T2 were observed in CPB-ARDS patients. A dynamic online predictive nomogram was developed based on three proteins (TXNDC5, CTSL, and NPC2) and two clinical risk factors (CPB time and massive blood transfusion), with excellent performance (precision: 83.33%, sensitivity: 93.33%, specificity: 61.16%, and F1 score: 85.05%). The mean area under the receiver operating characteristics curve (AUC) of the model after 10-fold cross-validation was 0.839 (95% CI: 0.824-0.855). Model discrimination and calibration were maintained during external validation dataset testing, with an AUC of 0.820 (95% CI: 0.685-0.955) and a Brier Score of 0.177 (95% CI: 0.147-0.206). Moreover, the considerably overexpressed TXNDC5 and CTSL proteins identified in the plasma of patients with CPB-ARDS, exhibited a significant upregulation in the lung tissue of LIRI rats.

CONCLUSIONS

This study identified several novel predictive biomarkers, developed and validated a practical prediction tool using biomarker and clinical factor combinations for individual prediction of CPB-ARDS risk. Assessing the plasma TXNDC5, CTSL, and NPC2 levels might identify patients who warrant closer follow-up and intensified therapy for ARDS prevention following major surgery.

CCN2 Activates RIPK3, NLRP3 Inflammasome, and NRF2/Oxidative Pathways Linked to Kidney Inflammation

Inflammation is a key characteristic of both acute and chronic kidney diseases. Preclinical data suggest the involvement of the NLRP3/Inflammasome, receptor-interacting protein kinase-3 (RIPK3), and NRF2/oxidative pathways in the regulation of kidney inflammation. Cellular communication network factor 2 (CCN2, also called CTGF in the past) is an established fibrotic biomarker and a well-known mediator of kidney damage. CCN2 was shown to be involved in kidney damage through the regulation of proinflammatory and profibrotic responses. However, to date, the potential role of the NLRP3/RIPK3/NRF2 pathways in CCN2 actions has not been evaluated. In experimental acute kidney injury induced with folic acid in mice, CCN2 deficiency diminished renal inflammatory cell infiltration (monocytes/macrophages and T lymphocytes) as well as the upregulation of proinflammatory genes and the activation of NLRP3/Inflammasome-related components and specific cytokine products, such as IL-1β. Moreover, the NRF2/oxidative pathway was deregulated. Systemic administration of CCN2 to C57BL/6 mice induced kidney immune cell infiltration and activated the NLRP3 pathway. RIPK3 deficiency diminished the CCN2-induced renal upregulation of proinflammatory mediators and prevented NLRP3 modulation. These data suggest that CCN2 plays a fundamental role in sterile inflammation and acute kidney injury by modulating the RIKP3/NLRP3/NRF2 inflammatory pathways.

GADD45A and GADD45B as Novel Biomarkers Associated with Chromatin Regulators in Renal Ischemia-Reperfusion Injury

Chromatin regulators (CRs) are essential upstream regulatory factors of epigenetic modification. The role of CRs in the pathogenesis of renal ischemia-reperfusion injury (IRI) remains unclear. We analyzed a bioinformatic analysis on the differentially expressed chromatin regulator genes in renal IRI patients using data from public domains. The hub CRs identified were used to develop a risk prediction model for renal IRI, and their expressions were also validated using Western blot, qRT-PCR, and immunohistochemistry in a murine renal IRI model. We also examined the relationships between hub CRs and infiltrating immune cells in renal IRI and used network analysis to explore drugs that target hub CRs and their relevant downstream microRNAs. The results of machine learning methods showed that five genes (DUSP1, GADD45A, GADD45B, GADD45G, HSPA1A) were upregulated in renal IRI, with key roles in the cell cycle, p38 MAPK signaling pathway, p53 signaling pathway, FoxO signaling pathway, and NF-κB signaling pathway. Two genes from the network, GADD45A and GADD45B (growth arrest and DNA damage-inducible protein 45 alpha and beta), were chosen for the renal IRI risk prediction model. They all showed good performance in the testing and validation cohorts. Mice with renal IRI showed significantly upregulated GADD45A and GADD45B expression within kidneys compared to sham-operated mice. GADD45A and GADD45B showed correlations with plasmacytoid dendritic cells (pDCs) in infiltrating immune cell analysis and enrichment in the MAPK pathway based on the weighted gene co-expression network analysis (WGCNA) method. Candidate drugs that target GADD45A and GADD45B include beta-escin, sertraline, primaquine, pimozide, and azacyclonol. The dysregulation of GADD45A and GADD45B is related to renal IRI and the infiltration of pDCs, and drugs that target GADD45A and GADD45B may have therapeutic potential for renal IRI.

Combined exposure to benzo(a)pyrene and dibutyl phthalate aggravates pro-inflammatory macrophage polarization in spleen via pyroptosis involving cathepsin B

Humans are often simultaneously exposed to benzo(a)pyrene (BaP) and dibutyl phthalate (DBP) through consumption of food and water. Yet, direct evidence of the link between BaP and DBP co-exposure and the risk of splenic injury is lacking. In the present study, we established the rats and primary splenic macrophages models to evaluate the effects of BaP or/and DBP exposure on spleen and underlying mechanisms. Compared to the single exposure or control groups, the co-exposure group showed more severe spleen damage and higher production of pro-inflammatory cytokines. Co-exposure to BaP and DBP resulted in a 1.79-fold, 2.11-fold and 1.9-fold increase in the M1 macrophage markers iNOS, NLRP3 (pyroptosis marker protein) and cathepsin B (CTSB), respectively, and a 0.8-fold decrease in the M2 macrophage marker Arg1 in vivo. The more prominent effects in perturbation of imbalance in M1/M2 polarization (iNOS, 2.25-fold; Arg1, 0.55-fold), pyroptosis (NLRP3, 1.43-fold), and excess CTSB (1.07-fold) in macrophages caused by BaP and DBP co-exposure in vitro were also found. Notably, MCC950 (the NLRP3-specific inhibitor) treatment attenuated the pro-inflammatory macrophage polarization and following pro-inflammatory cytokine production triggered by BaP and DBP co-exposure. Furthermore, CA-074Me (the CTSB-specific inhibitor) suppressed the macrophages pyroptosis, pro-inflammatory macrophage polarization, and secretion of pro-inflammatory cytokine induced by BaP and DBP co-exposure. In conclusion, this study indicates co-exposure to BaP and DBP poses a higher risk of spleen injury. Pro-inflammatory macrophage polarization regulated by pyroptosis involving CTSB underlies the spleen injury caused by BaP and DBP co-exposure.

Chloroquine inhibits NLRP3 inflammasomes activation and alleviates renal fibrosis in mouse model of hyperuricemic nephropathy with aggravation by a high-fat-diet

Numerous epidemiological studies have demonstrated that hyperuricemia (HUA) is a risk factor for renal diseases and renal fibrosis. Dietary patterns can influence serum urate levels and hyperuricemic nephropathy (HN). NLRP3 inflammasomes play a crucial role in various inflammatory responses and contribute to HN progression. Chloroquine (CQ) is an anti-inflammatory and disease-modifying anti-rheumatic drug (DMARD) utilized in treating autoimmune diseases such as rheumatoid arthritis and systemic lupus erythematosus. In this study, we examined the effects and underlying mechanisms of CQ in a high-fat-diet (HFD) exacerbated mouse model of HN. C57BL/6 mice were randomized into either a control group or an HN group (induced by adenine/potassium oxonate treatment), followed by a normal diet or HFD, with or without CQ treatment. Our findings revealed that the HN group exhibited elevated serum levels of blood urea nitrogen (BUN) and creatinine compared to the control group. Additionally, the HN + HFD group displayed increased serum levels of uric acid, BUN, and creatinine relative to the control + HFD group. Moreover, the HFD exacerbated renal uric acid crystal deposition and fibrosis in HN mice compared to a normal diet. CQ ameliorated renal dysfunction, as evidenced by reduced serum creatinine levels, renal fibrosis, and renal tubular injury scores, and significantly decreased NLRP3, ASC, caspase-1, and IL-1β levels in HN mice. These findings suggest that CQ inhibits the activation of NLRP3 inflammasomes and may serve as a potential therapeutic strategy for HN treatment.

Trimethylamine N-Oxide (TMAO) Inducing Endothelial Injury: UPLC-MS/MS-Based Quantification and the Activation of Cathepsin B-Mediated NLRP3 Inflammasome

TMAO is a new risk biomarker for cardiovascular disease. With trimethylammonium as its main chemical skeleton, TMAO is structurally similar to many endogenous metabolites, such as acetylcholine, carnitine, phosphorylcholine, etc. The mechanism of TMAO on the pathological process of CVD is still unclear. In this study, the quantitative analysis of plasma TMAO is conducted, and the contribution of Cathepsin B and NLRP3 inflammasome during the process of TMAO-induced endothelial injury was proposed and investigated at animal and cellular levels. Immunofluorescence assay was applied to represent the protein expression of Cathepsin B and NLRP3 inflammasome located at endothelial cells. The results showed that TMAO could disrupt endothelial cells permeability to induce endothelial injury, meanwhile, TMAO could increase NLRP3 inflammasome activation and promote the activity and expression of Cathepsin B in vitro and in vivo, whereas inhibition of NLRP3 inflammasome activation by MCC950 could protect the endothelial cells from TMAO associated endothelial injury via Cathepsin B. The study reveals that TMAO can cause endothelial injury via Cathepsin B-dependent NLRP3 inflammasome, and inhibition of Cathepsin B and NLRP3 inflammasome can reduce the TMAO-induced damage. The results provide new insight into the role of TMAO in CVD, which can be a potential therapeutic target for disease treatment and drug design.

Mechanistic Insights into the Role of OPN in Mediating Brain Damage via Triggering Lysosomal Damage in Microglia/Macrophage

We previously found that osteopontin (OPN) played a role in hypoxia–ischemia (HI) brain damage. However, its underlying mechanism is still unknown. Bioinformatics analysis revealed that the OPN protein was linked to the lysosomal cathepsin B (CTSB) and galectin-3 (GAL-3) proteins after HI exposure. In the present study, we tested the hypothesis that OPN was able to play a critical role in the lysosomal damage of microglia/macrophages following HI insult in neonatal mice. The results showed that OPN expression was enhanced, especially in microglia/macrophages, and colocalized with lysosomal-associated membrane protein 1 (LAMP1) and GAL-3; this was accompanied by increased LAMP1 and GAL-3 expression, CTSB leakage, as well as impairment of autophagic flux in the early stage of the HI process. In addition, the knockdown of OPN expression markedly restored lysosomal function with significant improvements in the autophagic flux after HI insult. Interestingly, cleavage of OPN was observed in the ipsilateral cortex following HI. The wild-type OPN and C-terminal OPN (Leu152-Asn294), rather than N-terminal OPN (Met1-Gly151), interacted with GAL-3 to induce lysosomal damage. Furthermore, the secreted OPN stimulated lysosomal damage by binding to CD44 in microglia in vitro. Collectively, this study demonstrated that upregulated OPN in microglia/macrophages and its cleavage product was able to interact with GAL-3, and secreted OPN combined with CD44, leading to lysosomal damage and exacerbating autophagosome accumulation after HI exposure.

Treating diabetes with combination of phosphodiesterase 5 inhibitors and hydroxychloroquine-a possible prevention strategy for COVID-19?

Type 2 diabetes (T2D) is one of the major risk factors for developing cardiovascular disease and the resultant devastating morbidity and mortality. The key features of T2D are hyperglycemia, hyperlipidemia, insulin resistance, and impaired insulin secretion. Patients with diabetes and myocardial infarction have worse prognosis than those without T2D. Moreover, obesity and T2D are recognized risk factors in developing severe form of COVID-19 with higher mortality rate. The current lines of drug therapy are insufficient to control T2D and its serious cardiovascular complications. Phosphodiesterase 5 (PDE5) is a cGMP specific enzyme, which is the target of erectile dysfunction drugs including sildenafil, vardenafil, and tadalafil. Cardioprotective effects of PDE5 inhibitors against ischemia/reperfusion (I/R) injury were reported in normal and diabetic animals. Hydroxychloroquine (HCQ) is a widely used antimalarial and anti-inflammatory drug and its hyperglycemia-controlling effect in diabetic patients is also under investigation. This review provides our perspective of a potential use of combination therapy of PDE5 inhibitor with HCQ to reduce cardiovascular risk factors and myocardial I/R injury in T2D. We previously observed that diabetic mice treated with tadalafil and HCQ had significantly reduced fasting blood glucose and lipid levels, increased plasma insulin and insulin-like growth factor-1 levels, and improved insulin sensitivity, along with smaller myocardial infarct size following I/R. The combination treatment activated Akt/mTOR cellular survival pathway, which was likely responsible for the salutary effects. Therefore, pretreatment with PDE5 inhibitor and HCQ may be a potentially useful therapy not only for controlling T2D but also reducing the rate and severity of COVID-19 infection in the vulnerable population of diabetics.

PRETREATMENT WITH ERYTHROPOIETIN ALLEVIATES THE RENAL DAMAGE INDUCED BY ISCHEMIA REPERFUSION VIA REPRESSION OF INFLAMMATORY RESPONSE

OBJECTIVE

The aim: This study aimed to examine the anti-inflammatory, and antiapoptotic effects of erythropoietin against kidney injury inducted by ischemia reperfusion in experimental model.

PATIENTS AND METHODS

Materials and methods: 20 male Sprague Dawley rats were randomly divided into 4 equal groups: sham (subject to median laparotomy only), control (subject to 30 minutes ischemia and 2hours reperfusion), vehicle (injected by distilled water and subjected to the same procedure of ischemia reperfusion), erythropoietin group (as in vehicle group but the rats pretreated with 1000 U/kg of erythropoietin). The left kidney and blood specimen were collected. The blood utilized to assess serum creatinine. While kidneys utilized to assessed MCP-1, TLR2, and caspase-3 in addition to histopathological evaluation.

RESULTS

Results: Control and vehicle samples showed that a significant elevation in serum creatinine, TLR2, caspase-3, and MCP-1 as compared with sham group. The histological eval¬uation showed a significant rise in kidney injury scores. Kidneys and blood samples of erythropoietin pretreated rats established histopathological and functional improvement as evidenced via reduced kidney injury scores in addition to the reduction in serum creatinine, as well as there were a significant diminished in caspase-3, MCP-1, and TLR2 levels when compared with control and vehicle groups.

CONCLUSION

Conclusions: Erythropoietin has renoprotective effect against ischemia and reperfusion, which achieved by decrease the inflammatory response as well as antiapoptotic effect.

The role of NLRP3 inflammasome in sepsis: A potential therapeutic target

Sepsis is the host immune imbalance following infection and leads to organ dysfunction, with highly complicated pathophysiology. To date, sepsis still lacks effective therapies with high mortality rates. Recently, numerous studies have highlighted the potential of NLRP3 inflammasome as a therapeutic target during sepsis. NLRP3 inflammasome is a protein complex that could induce the activation of caspase-1 and the following release of pro-inflammatory cytokines such as IL-1β and IL-18. It was demonstrated that NLRP3 inflammasome was involved in the development and progression of sepsis. In contrast, inhibition of NLRP3 inflammasome activation could mitigate the inflammatory response, protect organ function, and improve outcomes and mortality. This paper illustrated the activation pathways of the NLRP3 inflammasome and its possible molecular mechanisms in the pathophysiology of sepsis. Meanwhile, the beneficial effects of inhibiting NLRP3 activation in sepsis-related organ damage were also presented. In addition, the diverse role of NLRP3 inflammasome in bacterial clearance was addressed. Of note, several herbal extracts targeting NLRP3 inflammasome in the treatment of sepsis were emphasized. We hope that this paper could provide a basis for further drug research targeting NLRP3 inflammasome.

CTSB promotes sepsis-induced acute kidney injury through activating mitochondrial apoptosis pathway

Background

Acute kidney injury is a common and severe complication of sepsis. Sepsis -induced acute kidney injury(S-AKI) is an independent risk factor for mortality among sepsis patients. However, the mechanisms of S-AKI are complex and poorly understand. Therefore, exploring the underlying mechanisms of S-AKI may lead to the development of therapeutic targets.

Method

A model of S-AKI was established in male C57BL/6 mice using cecal ligation and puncture (CLP). The data-independent acquisition (DIA)-mass spectrometry-based proteomics was used to explore the protein expression changes and analyze the key proteomics profile in control and CLP group. The methodology was also used to identify the key proteins and pathways. S-AKI in vitro was established by treating the HK-2 cells with lipopolysaccharide (LPS). Subsequently, the effect and mechanism of Cathepsin B (CTSB) in inducing apoptosis in HK-2 cells were observed and verified.

Results

The renal injury scores, serum creatinine, blood urea nitrogen, and kidney injury molecule 1 were higher in septic mice than in non-septic mice. The proteomic analysis identified a total of 449 differentially expressed proteins (DEPs). GO and KEGG analysis showed that DEPs were mostly enriched in lysosomal-related cell structures and pathways. CTSB and MAPK were identified as key proteins in S-AKI. Electron microscopy observed enlarged lysosomes, swelled and ruptured mitochondria, and cytoplasmic vacuolization in CLP group. TUNEL staining and CTSB activity test showed that the apoptosis and CTSB activity were higher in CLP group than in control group. In HK-2 cell injury model, the CTSB activity and mRNA expression were increased in LPS-treated cells. Acridine orange staining showed that LPS caused lysosomal membrane permeabilization (LMP). CA074 as an inhibitor of CTSB could effectively inhibit CTSB activity. CCK8 and Annexin V/PI staining results indicated that CA074 reversed LPS-induced apoptosis of HK-2 cells. The JC-1 and western blot results showed that LPS inhibited mitochondrial membrane potential and activated mitochondrial apoptosis pathway, which could be reversed by CA074.

Conclusions

LMP and CTSB contribute to pathogenesis of S-AKI. LPS treatment induced HK-2 cell injury by activating mitochondrial apoptosis pathway. Inhibition of CTSB might be a new therapeutic strategy to alleviate sepsis-induced acute kidney injury.

Hydroxychloroquine Mitigates Dilated Cardiomyopathy Phenotype in Transgenic D94A Mice

In this study, we aimed to investigate whether short-term and low-dose treatment with hydroxychloroquine (HCQ), an antimalarial drug, can modulate heart function in a preclinical model of dilated cardiomyopathy (DCM) expressing the D94A mutation in cardiac myosin regulatory light chain (RLC) compared with healthy non-transgenic (NTg) littermates. Increased interest in HCQ came with the COVID-19 pandemic, but the risk of cardiotoxic side effects of HCQ raised concerns, especially in patients with an underlying heart condition, e.g., cardiomyopathy. Effects of HCQ treatment vs. placebo (H₂O), administered in Tg-D94A vs. NTg mice over one month, were studied by echocardiography and muscle contractile mechanics. Global longitudinal strain analysis showed the HCQ-mediated improvement in heart performance in DCM mice. At the molecular level, HCQ promoted the switch from myosin's super-relaxed (SRX) to disordered relaxed (DRX) state in DCM-D94A hearts. This result indicated more myosin cross-bridges exiting a hypocontractile SRX-OFF state and assuming the DRX-ON state, thus potentially enhancing myosin motor function in DCM mice. This bottom-up investigation of the pharmacological use of HCQ at the level of myosin molecules, muscle fibers, and whole hearts provides novel insights into mechanisms by which HCQ therapy mitigates some abnormal phenotypes in DCM-D94A mice and causes no harm in healthy NTg hearts.

GCN5L1-mediated TFAM acetylation at K76 participates in mitochondrial biogenesis in acute kidney injury

BACKGROUND

Mitochondrial dysfunction is an important pathogenic event in acute kidney injury (AKI). GCN5L1 is a specific acetyltransferase in mitochondria, which regulates glucose and fatty acid metabolism. However, the role of GCN5L1 in mitochondrial dysfunction and the pathogenesis of ischemic AKI are not fully understood.

METHODS

The protein level of GCN5L1 was detected by western blot assay. Acetylated proteomics was used to explore the level of acetylated TFAM. Duolink proximity ligation assay and co-immunoprecipitation were used to detect the interaction of TFAM and translocase of outer membrane 70 (TOM70). mtDNA copy number, the expression of mitochondrial electron transport chain complexes, the number and morphology of mitochondria were measured. The renal injury of AKI mice was reflected by the levels of creatinine and urea nitrogen and the pathological changes of renal tissue.

RESULTS

We showed that GCN5L1 was highly expressed in vivo and in vitro and renal tubules specific knockdown of GCN5L1 could effectively attenuate AKI-induced mitochondrial impairment. Besides, acetylated proteomics revealed that acetylated TFAM was significantly upregulated in AKI mice kidney, which reminded us that TFAM might be an acetylating substrate of GCN5L1. Mechanistically, we evidenced that GCN5L1 could acetylate TFAM at its K76 site and subsequently inhibited its binding to TOM70, thereby reducing TFAM import into mitochondria and mitochondrial biogenesis. Clinically, GCN5L1 and acetylated TFAM were positively correlated with disease severity (all p < 0.05).

CONCLUSIONS

In sum, these data demonstrated an unrecognized regulating mechanism of GCN5L1 on TFAM acetylation and its intracellular trafficking, and a potential intervening target for AKI associated mitochondrial disorders as well.

KCNQ1OT1 Influences HK-2 Apoptosis and Inflammation in LPS-Induced Acute Renal Injury via Modulating miR-30a-5p/NLRP3 Axis

Objective

To investigate the influence of KCNQ1OT1 on HK-2 apoptosis and inflammation in ARI and its molecular mechanism.

Methods

Normal cultivated HK-2 cells were used as negative control (NC) group. Three different concentrations of lipopolysaccharide (LPS) were used to treat the cells (5 μg/mL, 10 μg/mL, and 20 μg/mL). The groups included si-KCN1OT1+ LPS, si-NC + LPS, miR-30a-5p + LPS, pcDNA-NLRP3+si-KCNQ1OT1 + LPS group, miR-NC + LPS group, and pcDNA + si-KCNQ1OT1 + LPS group. CCK-8 and flow cytometry are used to measure cell viability and apoptosis, while RT-qPCR and Western blotting are used to detect KCNQ1OT1, miR-30a-5p, and NLRP3 mRNA. ELISA was used to detect the levels of TNF-α, IL-6, and IL-1β in HK-2 cells. The targeting relationship among KCNQ1OT1, miR-30a-5p, and NLRP3 was verified.

Results

After the intervention of LPS, the viability of HK-2 cells was decreased, while the apoptosis rates were increased. The mRNA and protein expressions of NLRP3 and KCNQ1OT1 were increased, while the mRNA and protein levels of miR-30a-5p were decreased (P < 0.05). The expressions of Bax and Cleaved-caspase-3 were downregulated after silencing KCNQ1OT1 and overexpressed miR-30a-5p. In addition, the viability of HK-2 cells was improved, and the apoptosis was reduced by inhibiting KCNQ1OT1 and overexpressed miR-30a-5p. Thus, KCNQ1OT1 modulated NLRP3 via targeting miR-30a-5p. Overexpression of NLRP3 reverses KCNQ1OT1 inhibition of LPS-induced apoptosis, activity, and inflammation in HK-2 cells.

Conclusions

Through modulating the miR-30a-5p/NLRP3 axis, inhibition of KCNQ1OT1 may reduce HK-2 apoptosis and inflammation in LPS-induced ARI.

Highly pathogenic coronaviruses and the kidney

Since the end of 2019, the outbreak of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has triggered a pneumonia epidemic, posing a significant public health challenge in 236 countries, territories, and regions worldwide. Clinically, in addition to the symptoms of pulmonary infection, many patients with SARS-CoV-2 infections, especially those with a critical illness, eventually develop multiple organ failure in which damage to the kidney function is common, ultimately leading to severe consequences such as increased mortality and morbidity. To date, three coronaviruses have set off major global public health security incidents: Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV), Middle East Respiratory Syndrome Coronavirus (MERS-CoV), and SARS-CoV-2. Among the diseases caused by the coronaviruses, the coronavirus disease 2019 (COVID-19) has been the most impactful and harmful. Similar to with SARS-CoV-2 infections, previous studies have shown that kidney injury is also common and prominent in patients with the two other highly pathogenic coronaviruses. Therefore, in this review, we aimed to comprehensively summarize the epidemiological and clinical characteristics of these three pandemic-level infections, provide a deep analysis of the potential mechanism of COVID-19 in various types of kidney diseases, and explore the causes of secondary kidney diseases of SARS-CoV-2, so as to provide a reference for further research and the clinical prevention of kidney damage caused by coronaviruses.

Multi‑faceted roles of cathepsins in ischemia reperfusion injury (Review)

Cathepsins are one of the most abundant proteases within the lysosomes with diverse physiological effects ranging from immune responses, cell death and intracellular protein degradation. Cathepsins are involved in extracellular and systemic functions such as systemic inflammation and extracellular matrix degradation. Ischemia reperfusion (IR) injury is responsible for numerous diseases including myocardial infarction, acute kidney injury, stroke and acute graft failure after transplant surgery. Inflammation plays a major role in the reperfusion phase of IR injury and previous research has shown that cathepsins are key mediators of the inflammation cascade as well as apoptosis. Taken together, cathepsins modulation could provide potential therapeutic approaches to attenuate IR injury. The present review summarized the current understanding of various cathepsin subtypes, their major physiologic functions, their roles in multi‑organ IR injury and detailed selective cathepsin inhibitors with therapeutic potential.

Caspase-1 and the inflammasome promote polycystic kidney disease progression

We and others have previously shown that the presence of renal innate immune cells can promote polycystic kidney disease (PKD) progression. In this study, we examined the influence of the inflammasome, a key part of the innate immune system, on PKD. The inflammasome is a system of molecular sensors, receptors, and scaffolds that responds to stimuli like cellular damage or microbes by activating Caspase-1, and generating critical mediators of the inflammatory milieu, including IL-1β and IL-18. We provide evidence that the inflammasome is primed in PKD, as multiple inflammasome sensors were upregulated in cystic kidneys from human ADPKD patients, as well as in kidneys from both orthologous (PKD1 RC/RC or RC/RC) and non-orthologous (jck) mouse models of PKD. Further, we demonstrate that the inflammasome is activated in female RC/RC mice kidneys, and this activation occurs in renal leukocytes, primarily in CD11c+ cells. Knock-out of Casp1, the gene encoding Caspase-1, in the RC/RC mice significantly restrained cystic disease progression in female mice, implying sex-specific differences in the renal immune environment. RNAseq analysis implicated the promotion of MYC/YAP pathways as a mechanism underlying the pro-cystic effects of the Caspase-1/inflammasome in females. Finally, treatment of RC/RC mice with hydroxychloroquine, a widely used immunomodulatory drug that has been shown to inhibit the inflammasome, protected renal function specifically in females and restrained cyst enlargement in both male and female RC/RC mice. Collectively, these results provide evidence for the first time that the activated Caspase-1/inflammasome promotes cyst expansion and disease progression in PKD, particularly in females. Moreover, the data suggest that this innate immune pathway may be a relevant target for therapy in PKD.

Exosomal transfer of microRNA-590-3p between renal tubular epithelial cells after renal ischemia-reperfusion injury regulates autophagy by targeting TRAF6

BACKGROUND

Acute kidney injury (AKI) is a common complication in patients, especially elderly patients, who undergo cardiac surgery with cardiopulmonary bypass. Studies have indicated a protective role of autophagy in AKI. However, the mechanisms underlying the regulatory effect of autophagy in AKI among patients undergoing cardiac surgeries are poorly understood. In this study, we aimed to test the hypothesis that exosomal microRNAs (miRNAs) regulate autophagy in tubular epithelial cells after AKI.

METHODS

Plasma exosomal RNA was extracted from young and elderly AKI patients undergoing cardiac surgery, and the miRNAs expression during the perioperative period were analyzed using next-generation sequencing. The screened miRNAs and their target genes were subjected to gene oncology function and Kyoto Encyclopedia of Genes and Genome enrichment analyses. Renal tubular epithelial cell line (HK-2 cells) was cultured and hypoxia/reoxygenation (H/R) model was established, which is an in vitro renal ischemia/reperfusion (I/R) model. We used Western blot analysis, cell viability assay, transfection, luciferase assay to investigate the mechanisms underlying the observed increases in the levels of renal I/R injury-mediated exosomal miRNAs and their roles in regulating HK-2 cells autophagy.

RESULTS

miR-590-3p was highly enriched in the plasma exosomes of young AKI patients after cardiac surgery. Increased levels of miR-590-3p led to the increases in the expression of autophagy marker proteins, including Beclin-1 and microtubule associated protein 1 light chain 3 beta (LC3II), and prolonged the autophagic response in HK-2 cells after H/R treatment. These effects were achieved mainly via increases in the exosomal miR-590-3p levels, and the tumor necrosis factor receptor-associated factor 6 protein was shown to play a key role in I/R injury-mediated autophagy induction.

CONCLUSION

Exosomes released from HK-2 cells after renal I/R injury regulate autophagy by transferring miR-590-3p in a paracrine manner, which suggests that increasing the miR-590-3p levels in HK-2 cell-derived exosomes may increase autophagy and protect against kidney injury after renal I/R injury.

Identification of core genes and pathways between geriatric multimorbidity and renal insufficiency: potential therapeutic agents discovered using bioinformatics analysis

Background

Geriatric people are prone to suffer from multiple chronic diseases, which can directly or indirectly affect renal function. Through bioinformatics analysis, this study aimed to identify key genes and pathways associated with renal insufficiency in patients with geriatric multimorbidity and explore potential drugs against renal insufficiency.

Methods

The text mining tool Pubmed2Ensembl was used to detect genes associated with the keywords including "Geriatric", "Multimorbidity" and "Renal insufficiency". The GeneCodis program was used to specify Gene Ontology (GO) biological process terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. Protein–protein interaction (PPI) networks were constructed using STRING and visualized in Cytoscape. Module analysis was performed using CytoHubba and Molecular Complex Detection (MCODE) plugins. GO and KEGG analysis of gene modules was performed using the Database for Annotation, Visualization and Integrated Discover (DAVID) platform database. Genes clustered in salient modules were selected as core genes. Then, the functions and pathways of core genes were visualized using ClueGO and CluePedia. Finally, the drug-gene interaction database was used to explore drug-gene interactions of the core genes to identify drug candidates for renal insufficiency in patients with geriatric multimorbidity.

Results

Through text mining, 351 genes associated with "Geriatric", "Multimorbidity" and "Renal insufficiency" were identified. A PPI network consisting of 216 nodes and 1087 edges was constructed and CytoHubba was used to sequence the genes. Five gene modules were obtained by MCODE analysis. The 26 genes clustered in module1 were selected as core candidate genes primarily associated with renal insufficiency in patients with geriatric multimorbidity. The HIF-1, PI3K-Akt, MAPK, Rap1, and FoxO signaling pathways were enriched. We found that 21 of the 26 selected genes could be targeted by 34 existing drugs.

Conclusion

This study indicated that CST3, SERPINA1, FN1, PF4, IGF1, KNG1, IL6, VEGFA, ALB, TIMP1, TGFB1, HGF, SERPINE1, APOA1, APOB, FGF23, EGF, APOE, VWF, TF, CP, GAS6, APP, IGFBP3, P4HB, and SPP1 were key genes potentially involved with renal insufficiency in patients with geriatric multimorbidity. In addition, 34 drugs were identified as potential agents for the treatment and management of renal insufficiency.

Cathepsin B/HSP70 complex induced by Ilexsaponin I suppresses NLRP3 inflammasome activation in myocardial ischemia/reperfusion injury

BACKGROUND

Myocardial ischemia/reperfusion injury (MI/RI) is a clinical issue in MI therapy that requires effective intervention. Cathepsin B (CTSB) plays an essential role in regulating cell death, inflammatory response and angiogenesis. Ilexsaponin I (ISI), a triterpenoid saponin obtained from Ilex pubescens Hook. et Arn, has anti-inflammatory and cardioprotective effects. However, the effect of ISI on MI/RI is unclear.

PURPOSE

The study aims to disclose the mechanism of ISI as a potent therapeutic agent for MI/RI.

METHODS

Left anterior descending (LAD) coronary artery ligation and oxygen-glucose deprivation and reperfusion (OGD/R) were used to establish MI/RI model in vivo and in vitro. ELISA, western blot and immunofluorescence were carried out to detect CTSB activity and NLRP3 inflammasome activation. Coimmunoprecipitation (Co-IP), molecular docking and surface plasmon resonance (SPR) analysis were used to detect the interaction of CTSB/HSP70 complex. Infarct area determination, echocardiography and hematoxylin and eosin (HE) staining were performed to assess the cardioprotection of ISI in vivo.

RESULTS

Plasma CTSB was elevated in patients after percutaneous coronary intervention (PCI), and was positively correlated with the level of cTnI in plasma, which was also found in MI/RI rat model. ISI significantly suppressed the overexpression and activity of CTSB after MI/RI or OGD/R. ISI remarkably suppressed CTSB triggered-NLRP3 inflammasome activation and reduced the maturation of IL-1β and IL-18. Importantly, we firstly found that ISI promoted CTSB/HSP70 complex formation to disrupt CTSB/NLRP3 complex, leading to NLRP3 inflammasome inactivation. ISI could also limit infarct size, improve cardiac function and reduce inflammatory infiltrates in vivo and protected H9c2 cells against OGD/R insult in vitro. Interrupting the HSP70 and CTSB interaction with HSP70 siRNA blocked the effect of ISI on CTSB, NLRP3 inflammasome activation and the cardioprotective effect.

CONCLUSION

ISI probably exerts cardioprotective effect against MI/RI by modulating HSP70 competitively bind to CTSB to suppress the activation of the NLRP3 inflammasome.

TRPC6 inhibits renal tubular epithelial cell pyroptosis through regulating zinc influx and alleviates renal ischemia-reperfusion injury

Canonical transient receptor potential-6 (TRPC6) has been reported to be involved in cell damage after ischemia/reperfusion (I/R) injury in target organs. While the effect and of TRPC6 on pyroptosis in renal I/R injury remain unclear. In our study, we first established the renal I/R mouse model and oxygen-glucose deprivation and re-oxygenation (OGD/R) cell model, and investigated the impacts of TRPC6 on the pyroptosis-related proteins using CCK-8, western blot, ELISA, and immunofluorescence probes. Besides, we also explored the mechanism of TRPC6 in pyroptosis of renal tubular epithelial cells through A20 knockdown or overexpression and zinc chloride (ZnCl₂ ) or a zinc ion chelator (TPEN) treatment. Our results indicated that I/R injury could cause downregulation of TRPC6 both in vivo and in vitro. In the I/R injury murine model, TRPC6 inhibition exacerbated tissue damage and upregulated NLRP3, ASC, caspase-1, IL-18, and IL-1β, which could be alleviated by the administration of ZnCl₂ . In the OGD/R cell model, inhibitor of TRPC6 (SAR7334) reduced zinc ion influx, aggravated cell death and upregulated pyroptosis-related protein. The pyroptosis phenotype also could be alleviated by ZnCl₂ and intensified by TPEN. Overexpression of A20 reduced the expression of pyroptosis-related protein, increased cell viability in the sh-TRPC6 and TPEN-treated OGD/R cell models, while A20 deficiency impaired the protective effect of zinc ion. Therefore, our results indicate that TRPC6 could promote zinc ion influx in renal tubular epithelial cells, thereby upregulating intracellular A20, inhibiting the activation of inflammasome NLRP3, and ultimately attenuating renal I/R injury.

Antiapoptotic Effects of Hydroxychloroquine on Hypoxic-Ischemic Injury in Neonatal Rat Brain: May Hydroxychloroquine Be an Adjuvant Theraphy?

OBJECTIVE

 Hydroxychloroquine (HCQ) has immunomodulatory, antithrombotic, cardiovascular, antimicrobial, and antineoplastic effects. In this study, we aimed to investigate the antiapoptotic and immunomodulator effects of intraperitoneal HCQ on hypoxic-ischemic (HI) injury in newborn rats.

STUDY DESIGN

 Wistar albino rats, 7 to 10 days old, were randomly divided into three groups: hypoxic-ischemic encephalopathy (HIE) group, HIE treated with HCQ group, and Sham group. Left common carotid artery ligation and hypoxia model were performed in HIE and HCQ groups. The HCQ group was treated with 80 mg/kg intraperitoneal HCQ every 24 hours for 3 days, while Sham and HIE groups were given physiological saline. After 72 hours, rats were decapitated and brain tissues were stained with hematoxylin and eosin, TUNEL, and IL-1β for histopathological grading and neuronal cell injury.

RESULTS

 Neuronal apoptosis was statistically lower in all neuroanatomical areas in the HCQ group compared with the HIE group. IL-1β-stained areas were similar in both HCQ and HIE groups but significantly higher compared with the Sham group. Histopathological grading scores were found to be lower in the HCQ group on the left parietal cortex and hippocampus region.

CONCLUSION

 In this study, we have shown for the first time that HCQ treatment decreased apoptosis in HI newborn rat model in both hemispheres. HCQ may be a promising adjuvant therapy in neonatal HIE.

KEY POINTS

· HCQ decreased neuronal apoptosis in the ischemic penumbra of the rat brain.. · HCQ attenuates hypoxia-ischemia-induced brain injury in neonatal rats.. · HCQ has no anti-inflammatory effect on HI injury..

NLRP3 inflammasome: A potential therapeutic target to minimize renal ischemia/reperfusion injury during transplantation

Renal transplantation is currently the best treatment option for patients with end-stage kidney disease. Ischemia/reperfusion injury (IRI), which is an inevitable event during renal transplantation, has a profound impact on the function of transplanted kidneys. It has been well demonstrated that innate immune system plays an important role in the process of renal IRI. As a critical component of innate immune system, Nod-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome has received great attention from scientific community over the past decade. The main function of NLRP3 inflammasome is mediating activation of caspase-1 and maturation of interleukin (IL)-1β and IL-18. In this review, we summarize the associated molecular signaling events about NLRP3 inflammasome in renal IRI, and highlight the possibility of targeting NLRP3 inflammasome to minimize renal IRI during transplantation.

Autophagy-dependent Na+-K+-ATPase signalling and abnormal urate reabsorption in hyperuricaemia-induced renal tubular injury

Increasing evidence indicates that hyperuricaemia (HUA) is not only a result of decreased renal urate excretion but also a contributor to kidney disease. Na⁺-K⁺-ATPase (NKA), which establishes the sodium gradient for urate transport in proximal tubular epithelial cells (PTECs), its impairment leads to HUA-induced nephropathy. However, the specific mechanism underlying NKA impairment-mediated renal tubular injury and increased urate reabsorption in HUA is not well understood. In this study, we investigated whether autophagy plays a key role in the NKA impairment signalling and increased urate reabsorption in HUA-induced renal tubular injury. Protein spectrum analysis of exosomes from the urine of HUA patients revealed the activation of lysosomal processes, and exosomal expression of lysosome membrane protein 2 was associated with increased serum levels and decreased renal urate excretion in patients. We demonstrated that high uric acid (UA) induced lysosome dysfunction, autophagy and inflammation in a time- and dose-dependent manner and that high UA and/or NKA α1 siRNA significantly increased mitochondrial abnormalities, such as reductions in mitochondrial respiratory complexes and cellular ATP levels, accompanied by increased apoptosis in cultured PTECs. The autophagy inhibitor hydroxychloroquine (HCQ) ameliorated NKA impairment-mediated mitochondrial dysfunction, Nod-like receptor pyrin domain-containing protein 3 (NLRP3)-interleukin-1β (IL-1β) production, and abnormal urate reabsorption in PTECs stimulated with high UA and in rats with oxonic acid (OA)-induced HUA. Our findings suggest that autophagy plays a pivotal role in NKA impairment-mediated signalling and abnormal urate reabsorption in HUA-induced renal tubular injury and that inhibition of autophagy by HCQ could be a promising treatment for HUA.

Extracellular vesicles for renal therapeutics: State of the art and future perspective

With the ever-increasing burden of kidney disease, the need for developing new therapeutics to manage this disease has never been greater. Extracellular vesicles (EVs) are natural membranous nanoparticles present in virtually all organisms. Given their excellent delivery capacity in the body, EVs have emerged as a frontier technology for drug delivery and have the potential to usher in a new era of nanomedicine for kidney disease. This review is focused on why EVs are such compelling drug carriers and how to release their fullest potentiality in renal therapeutics. We discuss the unique features of EVs compared to artificial nanoparticles and outline the engineering technologies and steps in developing EV-based therapeutics, with an emphasis on the emerging approaches to target renal cells and prolong kidney retention. We also explore the applications of EVs as natural therapeutics or as drug carriers in the treatment of renal disorders and present our views on the critical challenges in manufacturing EVs as next-generation renal therapeutics.

Effects of Drugs Formerly Suggested for COVID-19 Repurposing on Pannexin1 Channels

Although many efforts have been made to elucidate the pathogenesis of COVID-19, the underlying mechanisms are yet to be fully uncovered. However, it is known that a dysfunctional immune response and the accompanying uncontrollable inflammation lead to troublesome outcomes in COVID-19 patients. Pannexin1 channels are put forward as interesting drug targets for the treatment of COVID-19 due to their key role in inflammation and their link to other viral infections. In the present study, we selected a panel of drugs previously tested in clinical trials as potential candidates for the treatment of COVID-19 early on in the pandemic, including hydroxychloroquine, chloroquine, azithromycin, dexamethasone, ribavirin, remdesivir, favipiravir, lopinavir, and ritonavir. The effect of the drugs on pannexin1 channels was assessed at a functional level by means of measurement of extracellular ATP release. Immunoblot analysis and real-time quantitative reversetranscription polymerase chain reaction analysis were used to study the potential of the drugs to alter pannexin1 protein and mRNA expression levels, respectively. Favipiravir, hydroxychloroquine, lopinavir, and the combination of lopinavir with ritonavir were found to inhibit pannexin1 channel activity without affecting pannexin1 protein or mRNA levels. Thusthree new inhibitors of pannexin1 channels were identified that, though currently not being used anymore for the treatment of COVID-19 patients, could be potential drug candidates for other pannexin1-related diseases.

NLRP3 Inflammasome Activation: A Therapeutic Target for Cerebral Ischemia–Reperfusion Injury

Millions of patients are suffering from ischemic stroke, it is urgent to figure out the pathogenesis of cerebral ischemia–reperfusion (I/R) injury in order to find an effective cure. After I/R injury, pro-inflammatory cytokines especially interleukin-1β (IL-1β) upregulates in ischemic brain cells, such as microglia and neuron. To ameliorate the inflammation after cerebral I/R injury, nucleotide-binding oligomerization domain (NOD), leucine-rich repeat (LRR), and pyrin domain-containing protein 3 (NLRP3) inflammasome is well-investigated. NLRP3 inflammasomes are complicated protein complexes that are activated by endogenous and exogenous danger signals to participate in the inflammatory response. The assembly and activation of the NLRP3 inflammasome lead to the caspase-1-dependent release of pro-inflammatory cytokines, such as interleukin (IL)-1β and IL-18. Furthermore, pyroptosis is a pro-inflammatory cell death that occurs in a dependent manner on NLRP3 inflammasomes after cerebral I/R injury. In this review, we summarized the assembly and activation of NLRP3 inflammasome; moreover, we also concluded the pivotal role of NLRP3 inflammasome and inhibitors, targeting the NLRP3 inflammasome in cerebral I/R injury.

The NLRP3 inflammasome in fibrosis and aging: The known unknowns

Aging-related diseases such as cancer, cardiovascular diseases, diabetes, and neurodegenerative diseases are often accompanied by fibrosis. The NLRP3 inflammasome triggers the inflammatory response and subsequently promotes fibrosis through pathogen-associated molecular patterns (PAMPs). In this review, we first introduce the general background and specific mechanism of NLRP3 in fibrosis. Second, we investigate the role of NLRP3 in fibrosis in different organs/tissues. Third, we discuss the relationship between NLRP3 and fibrosis during aging. In summary, this review describes the latest progress on the roles of NLRP3 in fibrosis and aging and reveals the possibility of NLRP3 as an antifibrotic and anti-aging treatment target.

The pathological role of damaged organelles in renal tubular epithelial cells in the progression of acute kidney injury

Acute kidney injury (AKI) is a common clinical condition associated with high morbidity and mortality. The pathogenesis of AKI has not been fully elucidated, with a lack of effective treatment. Renal tubular epithelial cells (TECs) play an important role in AKI, and their damage and repair largely determine the progression and prognosis of AKI. In recent decades, it has been found that the mitochondria, endoplasmic reticulum (ER), lysosomes, and other organelles in TECs are damaged to varying degrees in AKI, and that they can influence each other through various signaling mechanisms that affect the recovery of TECs. However, the association between these multifaceted signaling platforms, particularly between mitochondria and lysosomes during AKI remains unclear. This review summarizes the specific pathophysiological mechanisms of the main TECs organelles in the context of AKI, particularly the potential interactions among them, in order to provide insights into possible novel treatment strategies.