Chemical mitochondrial uncouplers share common inhibitory effect on NLRP3 inflammasome activation through inhibiting NFκB nuclear translocation

Exploring the role of mitochondrial uncoupling protein 4 in brain metabolism: implications for Alzheimer's disease

The brain's high demand for energy necessitates tightly regulated metabolic pathways to sustain physiological activity. Glucose, the primary energy substrate, undergoes complex metabolic transformations, with mitochondria playing a central role in ATP production via oxidative phosphorylation. Dysregulation of this metabolic interplay is implicated in Alzheimer's disease (AD), where compromised glucose metabolism, oxidative stress, and mitochondrial dysfunction contribute to disease progression. This review explores the intricate bioenergetic crosstalk between astrocytes and neurons, highlighting the function of mitochondrial uncoupling proteins (UCPs), particularly UCP4, as important regulators of brain metabolism and neuronal function. Predominantly expressed in the brain, UCP4 reduces the membrane potential in the inner mitochondrial membrane, thereby potentially decreasing the generation of reactive oxygen species. Furthermore, UCP4 mitigates mitochondrial calcium overload and sustains cellular ATP levels through a metabolic shift from mitochondrial respiration to glycolysis. Interestingly, the levels of the neuronal UCPs, UCP2, 4 and 5 are significantly reduced in AD brain tissue and a specific UCP4 variant has been associated to an increased risk of developing AD. Few studies modulating the expression of UCP4 in astrocytes or neurons have highlighted protective effects against neurodegeneration and aging, suggesting that pharmacological strategies aimed at activating UCPs, such as protonophoric uncouplers, hold promise for therapeutic interventions in AD and other neurodegenerative diseases. Despite significant advances, our understanding of UCPs in brain metabolism remains in its early stages, emphasizing the need for further research to unravel their biological functions in the brain and their therapeutic potential.

Platelet-rich plasma-derived extracellular vesicles inhibit NF-κB/NLRP3 pathway-mediated pyroptosis in intervertebral disc degeneration via the MALAT1/microRNA-217/SIRT1 axis

BACKGROUND

Intervertebral disc degeneration (IDD) is a main contributor to lower back pain, and compression stress-induced apoptosis of nucleus pulposus (NP) cells and extracellular matrix (ECM) degradation has been implicated in the IDD progression. The functions of platelet-rich plasma (PRP)-derived extracellular vesicles (PRP-EVs) in regulating these biological processes remain unclear in IDD. Here, we aimed to investigate the key role of long noncoding RNA (lncRNA) MALAT1 incorporated in PRP-EVs in IDD.

METHODS

Tert-butyl hydroperoxide (TBHP)-induced damage in NP cells was treated with PRP-EVs extracted from healthy volunteers, followed by MTT, EdU, TUNEL, and Western blot assays. IDD mice were also treated with PRP-EVs. Histomorphological and pathological changes were evaluated. The pyroptosis of cells and the degradation of ECM were detected by ELISA and immunohistochemistry. We screened the differentially expressed lncRNAs in NP cells after PRP-EVs treatment by microarray analysis. The downstream targets of MALAT1 in NP cells were predicted and validated by rescue experiments.

FINDINGS

TBHP induction reduced cell proliferation and exacerbated pyroptosis and ECM degradation, and PRP-EVs inhibited TBHP-induced cell damage. PRP-EVs-treated mice with IDD had reduced Thompson scores, increased NP tissue content, and restored ECM. PRP-EVs upregulated MALAT1 expression in vivo and in vitro, whereas MALAT1 downregulation exacerbated NP cell pyroptosis and ECM degradation. MALAT1 upregulated SIRT1 expression by downregulating microRNA (miR)-217 in NP cells. SIRT1 blocked the NF-κB/NLRP3 pathway-mediated pyroptosis, thereby alleviating IDD.

INTERPRETATION

PRP-EVs deliver MALAT1 to regulate miR-217/SIRT1, thereby controlling NP cell pyroptosis in IDD.

Sorafenib extends the lifespan of C. elegans through mitochondrial uncoupling mechanism

Sorafenib is a targeted anticancer drug in clinic. Low-dose sorafenib has been reported to activate AMPK through inducing mitochondrial uncoupling without detectable toxicities. AMPK activation has been the approach for extending lifespan, therefore, we investigated the effect of sorafenib on lifespan and physical activity of C. elegans and the underlying mechanisms. In the present study, we found that the effect of sorafenib on C. elegans lifespan was typically hermetic. Sorafenib treatment at higher concentrations (100 μM) was toxic but at lower concentrations (1, 2.5, 5 μM) was beneficial to C. elegans. Sorafenib (1 μM) treatment for whole-life period extended C. elegans lifespan and improved C. elegans physical activity as manifested by increasing pharyngeal pumping and body movement, preserving intestinal barrier integrity, muscle fibers organization and mitochondrial morphology. In addition, sorafenib (1 μM) treatment enhanced C. elegans stress resistance. Sorafenib activated AMPK through inducing mitochondrial uncoupling in C. elegans. Sorafenib treatment activated DAF-16, SKN-1, and increased SOD-3, HSP-16.2, GST-4 expression in C. elegans. Sorafenib treatment induced AMPK-dependent autophagy in C. elegans. We conclude that low-dose sorafenib protects C. elegans against aging through activating AMPK/DAF-16 dependent anti-oxidant pathways and stimulating autophagy responses. Low-dose sorafenib could be a strategy for treating aging and aging-related diseases.

Anthelmintic nitazoxanide protects against experimental pulmonary fibrosis

BACKGROUND AND PURPOSE

Nitazoxanide is a therapeutic anthelmintic drug. Our previous studies found that nitazoxanide and its metabolite tizoxanide activated adenosine 5'-monophosphate-activated protein kinase (AMPK) and inhibited signal transducer and activator of transcription 3 (STAT3) signals. As AMPK activation and/or STAT3 inhibition are targets for treating pulmonary fibrosis, we hypothesized that nitazoxanide would be effective in experimental pulmonary fibrosis.

EXPERIMENTAL APPROACH

The mitochondrial oxygen consumption rate of cells was measured by using the high-resolution respirometry system Oxygraph-2K. The mitochondrial membrane potential of cells was evaluated by tetramethyl rhodamine methyl ester (TMRM) staining. The target protein levels were measured by using western blotting. The mice pulmonary fibrosis model was established through intratracheal instillation of bleomycin. The examination of the lung tissues changes were carried out using haematoxylin and eosin (H&E), and Masson staining.

KEY RESULTS

Nitazoxanide and tizoxanide activated AMPK and inhibited STAT3 signalling in human lung fibroblast cells (MRC-5 cells). Nitazoxanide and tizoxanide inhibited transforming growth factor-β1 (TGF-β1)-induced proliferation and migration of MRC-5 cells, collagen-I and α-smooth muscle cell actin (α-SMA) expression, and collagen-I secretion from MRC-5 cells. Nitazoxanide and tizoxanide inhibited epithelial-mesenchymal transition (EMT) and inhibited TGF-β1-induced Smad2/3 activation in mouse lung epithelial cells (MLE-12 cells). Oral administration of nitazoxanide reduced the bleomycin-induced mice pulmonary fibrosis and, in the established bleomycin-induced mice, pulmonary fibrosis. Delayed nitazoxanide treatment attenuated the fibrosis progression.

CONCLUSIONS AND IMPLICATIONS

Nitazoxanide improves the bleomycin-induced pulmonary fibrosis in mice, suggesting a potential application of nitazoxanide for pulmonary fibrosis treatment in the clinic.

BAM15 as a mitochondrial uncoupler: a promising therapeutic agent for diverse diseases

Subcellular organelles dysfunction is implicated in various diseases, including metabolic diseases, neurodegenerative diseases, cancer, and cardiovascular diseases. BAM15, a selective mitochondrial uncoupler, has emerged as a promising therapeutic agent due to its ability to enhance mitochondrial respiration and metabolic flexibility. By disrupting the coupling between electron transport and ATP synthesis, BAM15 dissipates the proton gradient, leading to increased mitochondrial respiration and energy expenditure. This review provides a comprehensive overview of BAM15, including its mechanism of action and potential therapeutic applications in diverse disease contexts. BAM15 has shown promise in obesity by increasing energy expenditure and reducing fat accumulation. In diabetes, it improves glycemic control and reverses insulin resistance. Additionally, BAM15 has potential in non-alcoholic fatty liver disease, sepsis, and cardiovascular diseases by mitigating oxidative stress, modulating inflammatory responses, and promoting cardioprotection. The safety profile of BAM15 is encouraging, with minimal adverse effects and remarkable tolerability. However, challenges such as its high lipophilicity and the need for alternative delivery methods need to be addressed. Further research is necessary to fully understand the therapeutic potential of BAM15 and optimize its application in clinical settings.

Repurposing Niclosamide as a Novel Anti-SARS-CoV-2 Drug by Restricting Entry Protein CD147

The outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to the global coronavirus disease 2019 (COVID-19) pandemic, and the search for effective treatments has been limited. Furthermore, the rapid mutations of SARS-CoV-2 have posed challenges to existing vaccines and neutralizing antibodies, as they struggle to keep up with the increased viral transmissibility and immune evasion. However, there is hope in targeting the CD147-spike protein, which serves as an alternative point for the entry of SARS-CoV-2 into host cells. This protein has emerged as a promising therapeutic target for the development of drugs against COVID-19. Here, we demonstrate that the RNA-binding protein Human-antigen R (HuR) plays a crucial role in the post-transcriptional regulation of CD147 by directly binding to its 3'-untranslated region (UTR). We observed a decrease in CD147 levels across multiple cell lines upon HuR depletion. Furthermore, we identified that niclosamide can reduce CD147 by lowering the cytoplasmic translocation of HuR and reducing CD147 glycosylation. Moreover, our investigation revealed that SARS-CoV-2 infection induces an upregulation of CD147 in ACE2-expressing A549 cells, which can be effectively neutralized by niclosamide in a dose-dependent manner. Overall, our study unveils a novel regulatory mechanism of regulating CD147 through HuR and suggests niclosamide as a promising therapeutic option against COVID-19.

Repurposing niclosamide as a novel anti-SARS-Cov-2 drug by restricting entry protein CD147

Background The burst of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is causing the global COVID-19 pandemic. But until today only limited numbers of drugs are discovered to treat COVID-19 patients. Even worse, the rapid mutations of SARS-CoV-2 compromise the effectiveness of existing vaccines and neutralizing antibodies due to the increased viral transmissibility and immune escape. CD147-spike protein, one of the entries of SRAR-CoV-2 into host cells, has been reported as a promising therapeutic target for developing drugs against COVID-19. Methods CRISPR-Cas9 induced gene knockout, western blotting, tet-off protein overexpression, ribonucleoprotein IP and RNA-IP were used to confirm the regulation of HuR on mRNA of CD147. Regulation of niclosamide on HuR nucleo-translocation was assessed by immunofluorescence staining of cell lines, IHC staining of tissue of mouse model and western blotting. Finally, the suppression of niclosamide on SARS-CoV-2 infection induced CD147 was evaluated by ACE2-expressing A549 cells and western blotting. Results We first discovered a novel regulation mechanism of CD147 via the RNA-binding protein HuR. We found that HuR regulates CD147 post-transcription by directly bound to its 3'-UTR. The loss of HuR reduced CD147 in multiple cell lines. Niclosamide inhibited CD147 function by blocking HuR cytoplasmic translocation and diminishing CD147 glycosylation. SARS-CoV-2 infection induced CD147 in ACE2-expressing A549 cells, which could be neutralized by niclosamide in a dose-dependent manner. Conclusion Together, our study reveals a novel regulation mechanism of CD147 and niclosamide can be repurposed as an effective COVID-19 drug by targeting the virus entry, CD147-spike protein.

Repurposing nitazoxanide as a novel anti-atherosclerotic drug based on mitochondrial uncoupling mechanisms

BACKGROUND AND PURPOSE

The anthelmintic drug nitazoxanide has a mitochondrial uncoupling effect. Mitochondrial uncouplers have been proven to inhibit smooth muscle cell proliferation and migration, inhibit NLRP3 inflammasome activation of macrophages and improve dyslipidaemia. Therefore, we aimed to demonstrate that nitazoxanide would protect against atherosclerosis.

EXPERIMENTAL APPROACH

The mitochondrial oxygen consumption of cells was measured by using the high-resolution respirometry system, Oxygraph-2K. The proliferation and migration of A10 cells were measured by using Edu immunofluorescence staining, wound-induced migration and the Boyden chamber assay. Protein levels were measured by using the western blot technique. ApoE (-/-) mice were fed with a Western diet to establish an atherosclerotic model in vivo.

KEY RESULTS

The in vitro experiments showed that nitazoxanide and tizoxanide had a mitochondrial uncoupling effect and activated cellular AMPK. Nitazoxanide and tizoxanide inhibited serum- and PDGF-induced proliferation and migration of A10 cells. Nitazoxanide and tizoxanide inhibited NLRP3 inflammasome activation in RAW264.7 macrophages, the mechanism by which involved the AMPK/IκBα/NF-κB pathway. Nitazoxanide and tizoxanide also induced autophagy in A10 cells and RAW264.7 macrophages. The in vivo experiments demonstrated that oral administration of nitazoxanide reduced the increase in serum IL-1β and IL-6 levels and suppressed atherosclerosis in Western diet-fed ApoE (-/-) mice.

CONCLUSION AND IMPLICATIONS

Nitazoxanide inhibits the formation of atherosclerotic plaques in ApoE (-/-) mice fed on a Western diet. In view of nitazoxanide being an antiprotozoal drug already approved by the FDA, we propose it as a novel anti-atherosclerotic drug with clinical translational potential.

Anthelmintics nitazoxanide protects against experimental hyperlipidemia and hepatic steatosis in hamsters and mice

Lipid metabolism disorders contribute to hyperlipidemia and hepatic steatosis. It is ideal to develop drugs simultaneous improving both hyperlipidemia and hepatic steatosis. Nitazoxanide is an FDA-approved oral antiprotozoal drug with excellent pharmacokinetic and safety profile. We found that nitazoxanide and its metabolite tizoxanide induced mild mitochondrial uncoupling and subsequently activated AMPK in HepG2 cells. Gavage administration of nitazoxanide inhibited high-fat diet (HFD)-induced increases of liver weight, blood and liver lipids, and ameliorated HFD-induced renal lipid accumulation in hamsters. Nitazoxanide significantly improved HFD-induced histopathologic changes of hamster livers. In the hamsters with pre-existing hyperlipidemia and hepatic steatosis, nitazoxanide also showed therapeutic effect. Gavage administration of nitazoxanide improved HFD-induced hepatic steatosis in C57BL/6J mice and western diet (WD)-induced hepatic steatosis in Apoe -/- mice. The present study suggests that repurposing nitazoxanide as a drug for hyperlipidemia and hepatic steatosis treatment is promising.

Anthelmintic niclosamide attenuates pressure-overload induced heart failure in mice

The heart is a high energy demand organ and enhancing mitochondrial function is proposed as the next-generation therapeutics for heart failure. Our previous study found that anthelmintic drug niclosamide enhanced mitochondrial respiration and increased adenosine triphosphate (ATP) production in cardiomyocytes, therefore, this study aimed to determine the effect of niclosamide on heart failure in mice and the potential molecular mechanisms. The heart failure model was induced by transverse aortic constriction (TAC) in mice. Oral administration of niclosamide improved TAC-induced cardiac hypertrophy, cardiac fibrosis, and cardiac dysfunction in mice. Oral administration of niclosamide reduced TAC-induced increase of serum IL-6 in heart failure mice. In vitro, niclosamide within 0.1 μM increased mitochondrial respiration and ATP production in mice heart tissues. At the concentrations more than 0.1 μM, niclosamide reduced the increased interleukin- 6 (IL-6) mRNA expression in lipopolysaccharide (LPS)-stimulated RAW264.7 and THP-1 derived macrophages. In cultured primary cardiomyocytes and cardiac fibroblasts, niclosamide (more than 0.1 μM) suppressed IL-6- and phenylephrine-induced cardiomyocyte hypertrophy, and inhibited collagen secretion from cardiac fibroblasts. In conclusion, niclosamide attenuates heart failure in mice and the underlying mechanisms include enhancing mitochondrial respiration of cardiomyocytes, inhibiting collagen secretion from cardiac fibroblasts, and reducing the elevated serum inflammatory mediator IL-6. The present study suggests that niclosamide might be therapeutic for heart failure.