Niclosamide attenuates inflammatory cytokines via the autophagy pathway leading to improved outcomes in renal ischemia/reperfusion injury

GDF15 Interference Regulates Proliferation, Inflammation, and Autophagy of Lipopolysaccharide-induced Mesangial Cells by Inhibiting PI3K/ AKT/mTOR Signaling

BACKGROUND

Chronic glomerulonephritis (CGN) is a primary glomerular disease. As a circulating protein, growth and differentiation factor 15 (GDF15) participates in a variety of biological processes.

OBJECTIVE

We aimed to investigate the role of GDF15 in CGN.

METHODS

HBZY-1 cells were induced by lipopolysaccharide (LPS). Cell viability was detected using a cell counting kit-8 (CCK-8) assay, and a western blot was applied for the detection of GDF15 protein expression. After GDF15 silencing, cell proliferation was evaluated by CCK-8 assay and 5-ethynyl-2'-deoxyuridine (EDU) staining. Enzyme-linked immunosorbent assay (ELISA) kits were used to detect the levels of inflammatory cytokines. Autophagy was assessed by GFP-LC3B assay. Besides, the expression of NF-κB signaling-, autophagy- (LC3II/I, Beclin l and p62) and phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/mechanistic target of rapamycin (mTOR) signaling-related proteins were measured by western blot. Afterwards, PI3K agonist 740Y-P was used to clarify whether GDF15 affected LPS-induced HBZY-1 cells via PI3K/AKT/mTOR signaling.

RESULTS

LPS induction increased cell viability and elevated GDF15 expression in HBZY-1 cells. After GDF15 expression depletion, the increased proliferation of LPS-induced HBZY-1 cells was decreased. Additionally, GDF15 knockdown suppressed the release of inflammatory factors in LPS-induced HBZY-1 cells and activated autophagy. Moreover, the PI3K/AKT/ mTOR signal was evidenced to be activated by GDF15 deficiency. The further addition of 740Y-P reversed the impacts of GDF15 deficiency on the proliferation, inflammation, and autophagy of LPS-induced HBZY-1.

CONCLUSION

Collectively, GDF15 downregulation could protect against CGN via blocking PI3K/AKT/mTOR signaling.

Mitochondrial Dysfunction in the Cardio-Renal Axis

Cardiovascular disease (CVD) frequently complicates chronic kidney disease (CKD). The risk of all-cause mortality increases from 20% to 500% in patients who suffer both conditions; this is referred to as the so-called cardio-renal syndrome (CRS). Preclinical studies have described the key role of mitochondrial dysfunction in cardiovascular and renal diseases, suggesting that maintaining mitochondrial homeostasis is a promising therapeutic strategy for CRS. In this review, we explore the malfunction of mitochondrial homeostasis (mitochondrial biogenesis, dynamics, oxidative stress, and mitophagy) and how it contributes to the development and progression of the main vascular pathologies that could be affected by kidney injury and vice versa, and how this knowledge may guide the development of novel therapeutic strategies in CRS.

Niclosamide modulates cyclosporin A-induced hepatotoxicity in a mouse model: PPAR-γ and Wnt/β-catenin crosstalk

OBJECTIVES

The aim of this study was to evaluate whether: 1) Wnt/β-catenin signaling is involved in cyclosporin A (CsA)-induced hepatotoxicity, and 2) knockdown of this pathway by niclosamide (NCL) attenuate CsA-induced hepatotoxicity.

METHODS

The experiment was accomplished in 21 days. Adult male mice were randomly distributed into five groups: control group, CsA (25 mg/kg/day) group, CsA + NCL (2.5 mg/kg/day) group, CsA + NCL (5 mg/kg/day) group, and NCL (5 mg/kg/day) group.

RESULTS

NCL showed marked hepatoprotection by significantly decreasing liver enzymes activities and ameliorating the histopathological alterations induced by CsA. Besides, NCL alleviated oxidative stress and inflammation. NCL-treated groups (2.5 and 5 mg/kg) displayed rise in the expression of hepatic peroxisome proliferator-activated receptor-γ (PPAR-γ) by 2.1- and 2.5-fold, respectively. Notably, NCL (2.5 and 5 mg/kg) significantly inhibited Wnt/β-catenin signaling, evidenced by a marked decrease in the hepatic expression of Wnt3a by 54 % and 50 %, frizzled-7 receptor by 50 % and 50 %, β-catenin by 22 % and 49 %, and c-myc by 50 % and 50 %, respectively.

CONCLUSIONS

NCL can be regarded as a potential agent to mitigate CsA-induced hepatotoxicity.

An update on the molecular mechanism and pharmacological interventions for Ischemia-reperfusion injury by regulating AMPK/mTOR signaling pathway in autophagy

AMP-activated protein kinase (5'-adenosine monophosphate-activated protein kinase, AMPK)/mammalian target of rapamycin (mTOR) is an important signaling pathway maintaining normal cell function and homeostasis in vivo. The AMPK/mTOR pathway regulates cellular proliferation, autophagy, and apoptosis. Ischemia-reperfusion injury (IRI) is secondary damage that frequently occurs clinically in various disease processes and treatments, and the exacerbated injury during tissue reperfusion increases disease-associated morbidity and mortality. IRI arises from multiple complex pathological mechanisms, among which cell autophagy is a focus of recent research and a new therapeutic target. The activation of AMPK/mTOR signaling in IRI can modulate cellular metabolism and regulate cell proliferation and immune cell differentiation by adjusting gene transcription and protein synthesis. Thus, the AMPK/mTOR signaling pathway has been intensively investigated in studies focused on IRI prevention and treatment. In recent years, AMPK/mTOR pathway-mediated autophagy has been found to play a crucial role in IRI treatment. This article aims to elaborate the action mechanisms of AMPK/mTOR signaling pathway activation in IRI and summarize the progress of AMPK/mTOR-mediated autophagy research in the field of IRI therapy.

Identification of immunomodulatory drugs that inhibit multiple inflammasomes and impair SARS-CoV-2 infection

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) induces mild or asymptomatic COVID-19 in most cases, but some patients develop an excessive inflammatory process that can be fatal. As the NLRP3 inflammasome and additional inflammasomes are implicated in disease aggravation, drug repositioning to target inflammasomes emerges as a strategy to treat COVID-19. Here, we performed a high-throughput screening using a 2560 small-molecule compound library and identified FDA-approved drugs that function as pan-inflammasome inhibitors. Our best hit, niclosamide (NIC), effectively inhibits both inflammasome activation and SARS-CoV-2 replication. Mechanistically, induction of autophagy by NIC partially accounts for inhibition of NLRP3 and AIM2 inflammasomes, but NIC-mediated inhibition of NAIP/NLRC4 inflammasome are autophagy independent. NIC potently inhibited inflammasome activation in human monocytes infected in vitro, in PBMCs from patients with COVID-19, and in vivo in a mouse model of SARS-CoV-2 infection. This study provides relevant information regarding the immunomodulatory functions of this promising drug for COVID-19 treatment.

Targeting the Wnt Signaling Pathway in Liver Fibrosis for Drug Options: An Update

Liver fibrosis is a life-threatening disease, with challenging morbidity and mortality for healthcare systems worldwide. It imparts an enormous economic burden to societies, making continuous research and informational updates about its pathogenesis and treatment crucial. This review's focus is on the current knowledge about the Wnt signaling pathway, serving as an important pathway in liver fibrosis development and activation of hepatic stellate cells (HSCs). Two types of Wnt pathways are distinguished, namely the ß-catenin-dependent canonical and non-canonical Ca²⁺ or planar cell polarity (PCP)-dependent pathway. The dynamic balance of physiologically healthy liver and hepatocytes is disturbed by repeated liver injuries. Activation of the ß-catenin Wnt pathway prevents the regeneration of hepatocytes by the replacement of extracellular matrix (ECM), leading to the appearance of scar tissue and the formation of regenerated nodular hepatocytes, lacking the original function of healthy hepatocytes. Therefore, liver function is reduced due to the severely advanced disease. Selective inhibition of ß-catenin inhibits inflammatory processes (since chemokines and pro-inflammatory cytokines are produced during Wnt activation), reduces growth of activated HSCs and reduces collagen synthesis and angiogenesis, thereby reducing the progression of liver fibrosis in vivo. While the canonical Wnt pathway is usually inactive in a physiologically healthy liver, it shows activity during cell regeneration or renewal and in certain pathophysiological conditions, such as liver diseases and cancer. Targeted blocking of some of the basic components of the Wnt pathway is a therapeutic approach. These include the frizzled transmembrane receptor (Fz) receptors using the secreted frizzled-related protein family (sFRP), Fz-coreceptors low-density LRP 5/6 through dickkopf-related protein 1 (DKK1) or niclosamide, glycogen kinase-3 beta (GSK-3β) using SB-216763, cyclic-AMP response element-binding protein (CBP) using PRI-724 and ICG-001, the lymphoid enhancer binding factor (LEF)/T cell-specific transcription factor (TCF) system as well as Wnt inhibitory factor 1 (WIF1) and miR-17-5p using pinostilbene hydrate (PSH). Significant progress has been made in inhibiting Wnt and thus stopping the progression of liver fibrosis by diminishing key components for its action. Comprehending the role of the Wnt signaling pathway in liver fibrosis may lead to discovery of novel targets in liver fibrosis therapeutic strategies' development.

Niclosamide for Covid-19: bridging the gap

AIM/PURPOSE

Niclosamide (NCL) is an anthelminthic drug, which is widely used to treat various diseases due to its pleiotropic anti-inflammatory and antiviral activities. NCL modulates of uncoupling oxidative phosphorylation and different signaling pathways in human biological processes. The wide-spectrum antiviral effect of NCL makes it a possible candidate for recent pandemic SARS-CoV-2 infection and may reduce Covid-19 severity. Therefore, the aim of the present study was to review and clarify the potential role of NCL in Covid-19.

METHODS

This study reviewed and highlighted the protective role of NCL therapy in Covid-19. A related literature search in PubMed, Scopus, Web of Science, Google Scholar, and Science Direct was done.

RESULTS

NCL has noteworthy anti-inflammatory and antiviral effects. The primary antiviral mechanism of NCL is through neutralization of endosomal PH and inhibition of viral protein maturation. NCL acts as a proton carrier, inhibits homeostasis of endosomal PH, which limiting of viral proliferation and release. The anti-inflammatory effects of NCL are mediated by suppression of inflammatory signaling pathways and release of pro-inflammatory cytokines. However, the major limitation in using NCL is low aqueous solubility, which reduces oral bioavailability and therapeutic serum concentration that reducing the in vivo effect of NCL against SARS-CoV-2.

CONCLUSIONS

NCL has anti-inflammatory and immune regulatory effects by modulating the release of pro-inflammatory cytokines, inhibition of NF-κB /NLRP3 inflammasome and mTOR signaling pathway. NCL has an anti-SARS-CoV-2 effect via interruption of viral life-cycle and/or induction of cytopathic effect. Prospective clinical studies and clinical trials are mandatory to confirm the potential role of NCL in patients with Covid-19 concerning the severity and clinical outcomes.

Drug Repurposing in Rare Diseases: An Integrative Study of Drug Screening and Transcriptomic Analysis in Nephropathic Cystinosis

Diagnosis and cure for rare diseases represent a great challenge for the scientific community who often comes up against the complexity and heterogeneity of clinical picture associated to a high cost and time-consuming drug development processes. Here we show a drug repurposing strategy applied to nephropathic cystinosis, a rare inherited disorder belonging to the lysosomal storage diseases. This approach consists in combining mechanism-based and cell-based screenings, coupled with an affordable computational analysis, which could result very useful to predict therapeutic responses at both molecular and system levels. Then, we identified potential drugs and metabolic pathways relevant for the pathophysiology of nephropathic cystinosis by comparing gene-expression signature of drugs that share common mechanisms of action or that involve similar pathways with the disease gene-expression signature achieved with RNA-seq.

The Mitochondrial Kinase PINK1 in Diabetic Kidney Disease

Mitochondria are critical organelles that play a key role in cellular metabolism, survival, and homeostasis. Mitochondrial dysfunction has been implicated in the pathogenesis of diabetic kidney disease. The function of mitochondria is critically regulated by several mitochondrial protein kinases, including the phosphatase and tensin homolog (PTEN)-induced kinase 1 (PINK1). The focus of PINK1 research has been centered on neuronal diseases. Recent studies have revealed a close link between PINK1 and many other diseases including kidney diseases. This review will provide a concise summary of PINK1 and its regulation of mitochondrial function in health and disease. The physiological role of PINK1 in the major cells involved in diabetic kidney disease including proximal tubular cells and podocytes will also be summarized. Collectively, these studies suggested that targeting PINK1 may offer a promising alternative for the treatment of diabetic kidney disease.

The role of WNT/β-catenin signaling pathway and glutamine metabolism in the pathogenesis of CCl4-induced liver fibrosis: Repositioning of niclosamide and concerns about lithium

BACKGROUND

Liver fibrosis is a serious health problem which may lead to advanced liver cirrhosis and hepatocellular carcinoma.

OBJECTIVE

The present study aimed to investigate the role of Wnt/β-catenin signaling pathway and glutamine aminohydrolase enzyme (l-glutaminase) in the pathogenesis of liver fibrosis and the potential benefits of niclosamide in treating liver fibrosis.

METHODS

Ninety male Albino rats were divided into 6 equal groups (n = 15) as follows: a normal control group (NC), CCl₄-only treated group (Fib.) which received 1 mg/kg CCl₄ two times weekly, niclosamide-treated group (Niclo.) which received 5 mg/kg of niclosamide one time daily, lithium chloride-treated group (LiCl) which received 100 mg/kg of LiCl one time daily, niclosamide-and-CCl₄-treated group (Niclo. + Fib.) which received same doses of niclosamide and CCl₄ given to other groups, and finally lithium chloride-and-CCl₄-treated rat group (LiCl + Fib.) which received same doses of LiCl and CCl₄ given to other groups. All treatments were administered orally for 8 weeks. Liver tissue was assessed for l-hydroxyproline, beta-catenin (β-catenin), l-glutaminase activity, as well as the gene expression of transforming growth factor beta-1 (TGF-β1) and Dishevelled-2 (Dvl2). Histopathological and immunohistochemical analyses of alpha smooth muscle actin α-SMA were performed. Serum alanine transaminase (ALT), aspartate transaminase (AST), and total bilirubin were measured.

RESULTS

The group of niclosamide-and-CCl₄-treated rats showed a significant decrease in total bilirubin, ALT and AST, β-catenin, l-hydroxyproline, l-glutaminase activity, and gene expression of TGF-β1 and Dvl2. Moreover, the liver tissue in this group of rats showed mild α-SMA reactivity compared with the rats treated with CCl₄ only (fibrosis group). On the other hand, lithium chloride-and-CCl₄-treated rats showed a significant increase in liver indices, TGF-β1 expression, β-catenin, l-hydroxyproline, and l-glutaminase activity with severe α-SMA reactivity and apoptosis in the liver tissue.

CONCLUSIONS

Niclosamide protected rats against liver fibrosis by inhibiting the Wnt/β-catenin pathway and glutaminolysis.

Protective role of Astragaloside IV in chronic glomerulonephritis by activating autophagy through PI3K/AKT/AS160 pathway

Astragaloside IV(AS-IV), a saponin purified from Astragalus membranaceus (Fisch.) Bge.var.mongholicus (Bge.) Hsiao, has been widely used in traditional Chinese medicine. However, the underlying mechanisms in treating chronic glomerular nephritis (CGN) have not been fully understood. The aim of the present study was to evaluate the potential mechanism of AS-IV on CGN. CGN rats were administrated with AS-IV at 10 mg·kg^-1 ·d^-1 (ASL) and 20 mg·kg^-1 ·d^-1 (ASH). Twenty four hour proteinuria, blood urea nitrogen (BUN), and serum creatinine (SCr) were detected. Hematoxylin-eosin (HE) and periodic acid-Schiff (PAS) staining were performed to evaluate the kidney lesion. Transmission electron microscope and GFP-RFP-LC3 transfection assay were used to monitor the effect of AS-IV on autophagy. IL-6 and IL-1β were detected. The expression of CyclinD1, PI3K/AKT/AS160 pathway and autophagy related proteins were detected by Western Blot. The results demonstrated that AS-IV improved kidney function, ameliorated kidney lesion, and diminished inflammatory in CGN rats. Further, both in vivo and vitro study demonstrated that AS-IV inhibited the proliferation of mesangial cells. AS-IV further displayed a remarkable effect on inhibiting the activation of PI3K/AKT/AS160 pathway and improved the activation of autophagy in vivo and vitro. These results suggested that AS-IV is a potential therapeutic agent for CGN and merits further investigation.

Effect of moxibustion preconditioning on autophagy-related proteins in rats with myocardial ischemia reperfusion injury

Background

Autophagy has increasingly been recognized as playing an essential role in the pathogenesis of myocardial ischemia reperfusion injury (MIRI). Moxibustion, a form of heat therapy commonly used in traditional Chinese medicine (TCM), has been shown to exhibit cardioprotective effects. However, whether the cardioprotective effect of moxibustion is related to the regulation of autophagy remains unknown. This study aimed to investigate the possible mechanism underlying the cardioprotective effect of moxibustion preconditioning at PC6 on MIRI by measuring the expressions of proteins involved in the regulation of autophagy.

Methods

Male Sprague-Dawley rats were randomly divided to receive moxibustion preconditioning or autophagy inhibitor 3-Methyladenine (3-MA) intervention. Then the MIRI model was established by ligating the left anterior descending (LAD) coronary artery for 30 minutes followed by reperfusion for 4 hours. After 4 hours of reperfusion, the myocardial infarction area was assessed using Evans blue and TTC staining, and cTnT and lactate dehydrogenase (LDH) levels in the serum were determined by ELISA. Hematoxylin and eosin (H&E) staining was performed for morphological evaluation of ventricular tissues. Expressions of autophagy components Beclin 1, Bcl-2, and Akt were assessed using quantitative real-time PCR, immunohistochemistry (IHC) and western blot.

Results

Moxibustion preconditioning significantly reduced the necrotic area and the levels of cTnT and LDH were similar to the 3-MA intervention, also attenuated morphological alterations were induced by MIRI. Simultaneously, the mRNA and protein expressions of Beclin 1 and Akt were up-regulated, while those of Bcl-2 were down-regulated by MIRI. Moxibustion preconditioning and 3-MA intervention reversed MIRI-induced changes in Beclin 1, Akt, and Bcl-2 expressions.

Conclusions

Moxibustion preconditioning at PC6 can attenuate myocardial injury for MIRI in a similar way to 3-MA intervention. This cardioprotective effect of moxibustion preconditioning may be mediated by modulating autophagy via regulation of Beclin 1, Bcl-2 and Akt.

Proximal Tubule Autophagy Differs in Type 1 and 2 Diabetes

BACKGROUND

Evidence of a protective role of autophagy in kidney diseases has sparked interest in autophagy as a potential therapeutic strategy. However, understanding how the autophagic process is altered in each disorder is critically important in working toward therapeutic applications.

METHODS

Using cultured kidney proximal tubule epithelial cells (PTECs) and diabetic mouse models, we investigated how autophagic activity differs in type 1 versus type 2 diabetic nephropathy. We explored nutrient signals regulating starvation-induced autophagy in PTECs and used autophagy-monitoring mice and PTEC-specific autophagy-deficient knockout mice to examine differences in autophagy status and autophagy's role in PTECs in streptozotocin (STZ)-treated type 1 and db/db type 2 diabetic nephropathy. We also examined the effects of rapamycin (an inhibitor of mammalian target of rapamycin [mTOR]) on vulnerability to ischemia-reperfusion injury.

RESULTS

Administering insulin or amino acids, but not glucose, suppressed autophagy by activating mTOR signaling. In db/db mice, autophagy induction was suppressed even under starvation; in STZ-treated mice, autophagy was enhanced even under fed conditions but stagnated under starvation due to lysosomal stress. Using knockout mice with diabetes, we found that, in STZ-treated mice, activated autophagy counteracts mitochondrial damage and fibrosis in the kidneys, whereas in db/db mice, autophagic suppression jeopardizes kidney even in the autophagy-competent state. Rapamycin-induced pharmacologic autophagy produced opposite effects on ischemia-reperfusion injury in STZ-treated and db/db mice.

CONCLUSIONS

Autophagic activity in PTECs is mainly regulated by insulin. Consequently, autophagic activity differs in types 1 and 2 diabetic nephropathy, which should be considered when developing strategies to treat diabetic nephropathy by modulating autophagy.

The Anthelmintic Drug Niclosamide Synergizes with Colistin and Reverses Colistin Resistance in Gram-Negative Bacilli

There is an urgent need for new therapies to overcome antimicrobial resistance especially in Gram-negative bacilli (GNB). Repurposing old U.S. Food and Drug Administration-approved drugs as complementary agents to existing antibiotics in a synergistic combination presents an attractive strategy. Here, we demonstrate that the anthelmintic drug niclosamide selectively synergized with the lipopeptide antibiotic colistin against colistin-susceptible but more importantly against colistin-resistant GNB, including clinical isolates that harbor the mcr-1 gene. Breakpoints for colistin susceptibility in resistant Gram-negative bacilli were reached in the presence of 1 μg/ml (3 μM) niclosamide. Reversal of colistin resistance was also observed in combinations of niclosamide and polymyxin B. Enhanced bacterial killing was evident for the combination, in comparison to colistin monotherapy, against resistant Pseudomonas aeruginosa, Acinetobacter baumannii, Klebsiella pneumoniae, Escherichia coli, and Enterobacter cloacae Accumulating evidence in the literature, along with our results, strongly suggests the potential for the combination of niclosamide and colistin to treat colistin-resistant Gram-negative bacillary infections. Our finding is significant since colistin is an antibiotic of last resort for multidrug-resistant Gram-negative bacterial infections that are nonresponsive to conventional treatments. With the recent global dissemination of plasmid-encoded colistin resistance, the addition of niclosamide to colistin therapy may hold the key to overcome colistin resistance.

ATG5-mediated autophagy suppresses NF-κB signaling to limit epithelial inflammatory response to kidney injury

G2/M-arrested proximal tubular epithelial cells (TECs) after renal injury are linked to increased cytokines production. ATG5-mediated autophagy in proximal TECs has recently been shown to protect against G2/M cell cycle arrest and renal fibrosis. However, the impacts of autophagy in regulating inflammatorily response mounted by injured TECs remains largely unknown. In the present study, we investigated whether ATG5 acts as an innate immune suppressor in proximal TECs during kidney injury. Using the unilateral ureteric obstruction model in proximal tubule-specific autophagy-deficient mice, we demonstrated that ablation of epithelial ATG5 genes markedly impaired autophagy, resulting in enhanced nuclear factor κB (NF-κB) activation, macrophage and lymphocyte infiltration, and proinflammatory cytokines production in obstructed kidneys, as compared with wild-type mice. Following stimulation with angiotensin II (Ang II), siRNA silencing of ATG5 in cultured HK-2 cells or ATG5-deficient primary proximal TECs produced more cytokines, including IL-1β, IL-6, and TNF-α than did their control cells. Overexpressed ATG5, but not the autophagy-incompetent ATG5 mutant K130R in HK-2 cells, rendered resistant to Ang II-induced inflammatory response. Immunofluorescence assay indicated that ATG5 and p65 colocalized in the nucleus and cytoplasm, and their interaction was verified in immunoprecipitation assay from HEK-293T cell extracts. Genetic downregulation of endogenous ATG5 increased Ang II-induced phosphorylation and nuclear translocation of p65 and transcriptional activity of NF-κB, whereas the overexpressed ATG5, rather than ATG5 mutant K130R, hampered activation of NF-κB signaling, suggest an autophagy-dependent anti-inflammatory effect of ATG5. Further, pharmacological manipulation of autophagy yielded similar results both in vivo and in vitro. Additionally, JSH-23, a specific inhibitor of NF-κB nuclear translocation, rescued Ang II-driven IL-1β production in ATG5 siRNA-treated cells and decreased the proportion of cells in G2/M phase. In conclusion, ATG5-mediated autophagy in tubules targets NF-κB signaling to protect against renal inflammation.

Aged kidneys are refractory to autophagy activation in a rat model of renal ischemia-reperfusion injury

Background

Ischemia-reperfusion (I/R) injury is the most common cause of acute kidney injury (AKI). Numerous therapeutic approaches for I/R injury have been studied, including autophagy, particularly in animal models of renal I/R injury derived from young or adult animals. However, the precise role of autophagy in renal ischemia-reperfusion in the aged animal model remains unclear. The purpose of this study was to demonstrate whether autophagy has similar effects on renal I/R injury in young and aged rats.

Materials and methods

All rats were divided into two age groups (3 months and 24 months) with each group being further divided into four subgroups (sham, I/R, I/R+Rap (rapamycin, an activator of autophagy), I/R+3-MA (3-methyladenine, an inhibitor of autophagy)). The I/R+Rap and I/R+3-MA groups were intraperitoneally injected with rapamycin and 3-MA prior to ischemia. We then measured serum levels of urea nitrogen, creatinine and assessed damage in the renal tissue. Immunohistochemistry was used to assess LC3-II and caspase-3, and Western blotting was used to evaluate the autophagy-related proteins LC3-II, Beclin-1 and P62. Apoptosis and autophagosomes were evaluated by TUNEL and transmission electron microscopy, respectively.

Results

Autophagy was activated in both young and aged rats by I/R and enhanced by rapamycin, although the level of autophagy was lower in the aged groups. In young rats, the activation of autophagy markedly improved renal function, reduced apoptosis in the renal tubular epithelial cells and the injury score in the renal tissue, thereby exerting protective effects on renal I/R injury. However, this level of protection was not present in aged rats.

Conclusion

Our data indicated that the activation of autophagy was ineffective in aged rat kidneys. These discoveries may have major implications in that severe apoptosis in aged kidneys might be refractory to antiapoptotic effect induced by the activation of autophagy.

Emerging Anti-Aging Strategies - Scientific Basis and Efficacy

The prevalence of age-related diseases is in an upward trend due to increased life expectancy in humans. Age-related conditions are among the leading causes of morbidity and death worldwide currently. Therefore, there is an urgent need to find apt interventions that slow down aging and reduce or postpone the incidence of debilitating age-related diseases. This review discusses the efficacy of emerging anti-aging approaches for maintaining better health in old age. There are many anti-aging strategies in development, which include procedures such as augmentation of autophagy, elimination of senescent cells, transfusion of plasma from young blood, intermittent fasting, enhancement of adult neurogenesis, physical exercise, antioxidant intake, and stem cell therapy. Multiple pre-clinical studies suggest that administration of autophagy enhancers, senolytic drugs, plasma from young blood, drugs that enhance neurogenesis and BDNF are promising approaches to sustain normal health during aging and also to postpone age-related neurodegenerative diseases such as Alzheimer's disease. Stem cell therapy has also shown promise for improving regeneration and function of the aged or Alzheimer's disease brain. Several of these approaches are awaiting critical appraisal in clinical trials to determine their long-term efficacy and possible adverse effects. On the other hand, procedures such as intermittent fasting, physical exercise, intake of antioxidants such as resveratrol and curcumin have shown considerable promise for improving function in aging, some of which are ready for large-scale clinical trials, as they are non-invasive, and seem to have minimal side effects. In summary, several approaches are at the forefront of becoming mainstream therapies for combating aging and postponing age-related diseases in the coming years.

Rapamycin induces autophagy to alleviate acute kidney injury following cerebral ischemia and reperfusion via the mTORC1/ATG13/ULK1 signaling pathway

Acute kidney injury (AKI) is a clinically common and severe complication of ischemia-reperfusion (I/R), associated with high morbidity and mortality rates, and prolonged hospitalization. Rapamycin is a type of macrolide, primarily used for anti-rejection therapy following organ transplantation and the treatment of autoimmune diseases. Rapamycin has been identified to exert a protective effect against AKI induced by renal I/R as an autophagy inducer. However, whether rapamycin preconditioning may relieve AKI following cerebral I/R (CIR) remains to be fully elucidated. The purpose of the present study was to investigate the effects of CIR on the renal system of rats and the role of rapamycin in AKI following CIR. In the present study, a CIR model was established in Sprague-Dawley rats via a 90-min period of middle cerebral artery occlusion and 24 h reperfusion, and pretreatment with an intraperitoneal injection of rapamycin (dosage: 1 mg/kg; 0.5 h) prior to CIR. The levels of serum creatinine and blood urea nitrogen (BUN), and the expression of inflammation-, apoptosis- and autophagy-associated markers were subsequently measured. In addition to certain histopathological alterations to the kidney, it was identified that CIR significantly increased the levels of serum creatinine, BUN, tumor necrosis factor-α and interleukin-1β, and significantly induced apoptosis and autophagy. It was observed that rapamycin induced autophagy through the mammalian target of rapamycin complex 1/autophagy-related 13/unc-51 like autophagy activating kinase 1 signaling pathway, and that rapamycin pre-treatment significantly improved renal function and alleviated renal tissue inflammation and cell apoptosis in rats following CIR. In conclusion, the results suggested that rapamycin may alleviate AKI following CIR via the induction of autophagy.

Role of capsaicin sensitive sensory nerves in ischemia reperfusion-induced acute kidney injury in rats

Acute kidney injury (AKI) is a common kidney disorder which is associated with a high risk of mortality. Extensive evidence revealed the participation of renal afferent sensory nerves in the pathophysiology of renal ischemia reperfusion (IR) injury, however the role of these nerves in renal IR injury is controversial and remains to be further explored. Here, we report that capsaicin sensitive sensory nerves and neuropeptides prevented renal damage in AKI induced by IR injury. The sensory afferent degeneration model was established by injecting 50 mg/kg of capsaicin to male neonatal rats and verified by the tail flick test and reduced sensory neuropeptide of substance P and calcitonin gene related peptide in spinal cord, dorsal root ganglion and kidney after 12 weeks. Then, a model of renal IR injury was established. The sensory afferent degeneration in the AKI group increased the level of serum creatinine, NGAL and KIM-1, aggravated to some extent renal pathological damage, and enhanced the proinflammatory cytokines expressions and tubular cell apoptosis. In addition, it was also discovered that the level of phospho-ERK/ERK (p-ERK/ERK) showed an increase in spinal cord and kidney after degeneration of capsaicin sensitive sensory nerves. In conclusion, the degeneration of sensory nerves aggravated IR-induced AKI in rats, and the activated ERK signaling in spinal cord and kidney after sensory afferent degeneration might be the possible mechanism in the aggravated renal injury.