Autophagy in Chronic Kidney Diseases

Impact of ciprofloxacin with autophagy on renal tubular injury

BACKGROUNDS

Renal tubular injury caused by oxidative stress and inflammation results in acute kidney injury. Recent research reported that antibiotics may protect renal tubules from progressive deterioration, but the underlying mechanism remains unclear. Therefore, we investigated the efficacy and mechanism of action of antibiotics against renal tubular injury.

METHODS

We screened ciprofloxacin, ceftizoxime, minocycline, and netilmicin and selected ciprofloxacin to examine further because of its low toxicity towards renal tubular cells. We evaluated the effect of ciprofloxacin on cell survival by analyzing apoptosis and autophagy.

RESULTS

Terminal deoxynucleotidyl transferase-mediated d-UTP nick end labeling (TUNEL) assay results showed that the ciprofloxacin group had less apoptotic cells than the control group. The ratio of cleaved caspase 3 to caspase 3, the final effector in the apoptosis process, was decreased, but the ratio of B-cell lymphoma 2 (Bcl-2)-associated X protein (Bax) to Bcl-2 located upstream of caspase 3 was not decreased in the ciprofloxacin group. Therefore, apoptosis inhibition does not occur via Bax/Bcl-2. Conversely, the levels of phosphorylated Bcl-2, and Beclin-1, an autophagy marker, were increased, and that of caspase-3 was decreased in the ciprofloxacin group.

CONCLUSION

This indicates that ciprofloxacin enhances autophagy, increasing the amount of free Beclin-1 via phosphorylated Bcl-2, and inhibits caspase activity. Therefore, ciprofloxacin might protect against renal tubular injury through the activation of autophagy in the setting of acute kidney injury.

JAK/STAT3 signaling in cardiac fibrosis: a promising therapeutic target

Cardiac fibrosis is a serious health problem because it is a common pathological change in almost all forms of cardiovascular diseases. Cardiac fibrosis is characterized by the transdifferentiation of cardiac fibroblasts (CFs) into cardiac myofibroblasts and the excessive deposition of extracellular matrix (ECM) components produced by activated myofibroblasts, which leads to fibrotic scar formation and subsequent cardiac dysfunction. However, there are currently few effective therapeutic strategies protecting against fibrogenesis. This lack is largely because the molecular mechanisms of cardiac fibrosis remain unclear despite extensive research. The Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling cascade is an extensively present intracellular signal transduction pathway and can regulate a wide range of biological processes, including cell proliferation, migration, differentiation, apoptosis, and immune response. Various upstream mediators such as cytokines, growth factors and hormones can initiate signal transmission via this pathway and play corresponding regulatory roles. STAT3 is a crucial player of the JAK/STAT pathway and its activation is related to inflammation, malignant tumors and autoimmune illnesses. Recently, the JAK/STAT3 signaling has been in the spotlight for its role in the occurrence and development of cardiac fibrosis and its activation can promote the proliferation and activation of CFs and the production of ECM proteins, thus leading to cardiac fibrosis. In this manuscript, we discuss the structure, transactivation and regulation of the JAK/STAT3 signaling pathway and review recent progress on the role of this pathway in cardiac fibrosis. Moreover, we summarize the current challenges and opportunities of targeting the JAK/STAT3 signaling for the treatment of fibrosis. In summary, the information presented in this article is critical for comprehending the role of the JAK/STAT3 pathway in cardiac fibrosis, and will also contribute to future research aimed at the development of effective anti-fibrotic therapeutic strategies targeting the JAK/STAT3 signaling.

Multipronged regulation of autophagy and apoptosis: emerging role of TRIM proteins

TRIM proteins are characterized by their conserved N-terminal RING, B-box, and coiled-coil domains. These proteins are efficient regulators of autophagy, apoptosis, and innate immune responses and confer immunity against viruses and bacteria. TRIMs function as receptors or scaffold proteins that target substrates for autophagy-mediated degradation. Most TRIMs interact with the BECN1-ULK1 complex to form TRIMosomes, thereby efficiently targeting substrates to autophagosomes. They regulate the functions of ATG proteins through physical interactions or ubiquitination. TRIMs affect the lipidation of MAP1LC3B1 to form MAP1LC3B2, which is a prerequisite for phagophore and autophagosome formation. In addition, they regulate MTOR kinase and TFEB, thereby regulating the expression of ATG genes. TRIM proteins are efficient regulators of apoptosis and are crucial for regulating cell proliferation and tumor formation. Many TRIM proteins regulate intrinsic and extrinsic apoptosis via the cell surface receptors TGFBR2, TNFRSF1A, and FAS. Mitochondria modulate the anti- and proapoptotic functions of BCL2, BAX, BAK1, and CYCS. These proteins use a multipronged approach to regulate the intrinsic and extrinsic apoptotic pathways, culminating in coordinated activation or inhibition of the initiator and executor CASPs. Furthermore, TRIMs can have a dual effect in determining cell fate and are therefore crucial for cellular homeostasis. In this review, we discuss mechanistic insights into the role of TRIM proteins in regulating autophagy and apoptosis, which can be used to better understand cellular physiology. These findings can be used to develop therapeutic interventions to prevent or treat multiple genetic and infectious diseases.

Cordyceps cicadae ameliorates inflammatory responses, oxidative stress, and fibrosis by targeting the PI3K/mTOR-mediated autophagy pathway in the renal of MRL/lpr mice

BACKGROUND

The vast majority of systemic lupus erythematosus patients develop lupus nephritis (LN) with severe renal manifestations, such as inflammatory responses, oxidative stress, and fibrosis. The purpose of this research was to investigate Cordyceps cicadae as a potential therapeutic target for treating inflammatory responses, oxidative stress, and fibrosis in LN.

METHODS

The effects of C. cicadae on lupus symptoms in mice with LN were determined. MRL/lpr mice were treated with C. cicadae (4 g/kg/day, i.e., CC group, n = 8) or an equal volume of saline (model group, n = 8), and MRL/MP mice were treated with an equal volume of saline (control group, n = 8). Renal function indices, renal pathology, inflammatory markers, oxidative stress markers, and renal interstitial fibrosis levels were evaluated after C. cicadae treatment. Western blot analysis was performed to investigate the effect of C. cicadae on the expression of fibrosis biomarkers and the phosphatidylinositol 3-kinase (PI3K)/mammalian target of rapamycin (mTOR)-mediated autophagy pathway in the renal tissues of mice.

RESULTS

C. cicadae ameliorated renal lesions, the inflammatory response, and oxidative stress damage in MRL/lpr mice. C. cicadae treatment inhibited renal fibrosis (16.31 ± 4.16 vs. 31.25 ± 5.61) and downregulated the expression of the fibrosis biomarkers alpha-smooth muscle actin, fibronectin, and collagen I (COL I) in the kidneys of MRL/lpr mice. In addition, further research showed that the PI3K/mTOR-mediated autophagy pathway was involved in C. cicadae-mediated effects on renal fibrosis in MRL/lpr mice. Furthermore, the therapeutic effect of C. cicadae on repairing renal fibrosis and damage in MRL/lpr mice was abolished by the PI3K agonist 740 Y-P.

CONCLUSIONS

The findings of the present research showed that C. cicadae could alleviate inflammatory responses, oxidative stress, and fibrosis in the renal tissues of mice with LN by targeting the PI3K/mTOR-mediated autophagy pathway.

Astragaloside IV Blunts Epithelial-Mesenchymal Transition and G2/M Arrest to Alleviate Renal Fibrosis via Regulating ALDH2-Mediated Autophagy

Previous studies show that astragaloside IV (ASIV) has anti-renal fibrosis effects. However, its mechanism remains elusive. In this study, we investigated the anti-fibrosis mechanisms of ASIV on chronic kidney disease (CKD) in vivo and in vitro. A CKD model was induced in rats with adenine (200 mg/kg/d, i.g.), and an in vitro renal fibrosis model was induced in human kidney-2 (HK-2) cells treated with TGF-β1. We revealed that ASIV significantly alleviated renal fibrosis by suppressing the expressions of epithelial-mesenchymal transition (EMT)-related proteins, including fibronectin, vimentin, and alpha-smooth muscle actin (α-SMA), and G2/M arrest-related proteins, including phosphorylated p53 (p-p53), p21, phosphorylated histone H3 (p-H3), and Ki67 in both of the in vivo and in vitro models. Transcriptomic analysis and subsequent validation showed that ASIV rescued ALDH2 expression and inhibited AKT/mTOR-mediated autophagy. Furthermore, in ALDH2-knockdown HK-2 cells, ASIV failed to inhibit AKT/mTOR-mediated autophagy and could not blunt EMT and G2/M arrest. In addition, we further demonstrated that rapamycin, an autophagy inducer, reversed the treatment of ASIV by promoting autophagy in TGF-β1-treated HK-2 cells. A dual-luciferase report assay indicated that ASIV enhanced the transcriptional activity of the ALDH2 promoter. In addition, a further molecular docking analysis showed the potential interaction of ALDH2 and ASIV. Collectively, our data indicate that ALDH2-mediated autophagy may be a novel target in treating renal fibrosis in CKD models, and ASIV may be an effective targeted drug for ALDH2, which illuminate a new insight into the treatment of renal fibrosis and provide new evidence of pharmacology to elucidate the anti-fibrosis mechanism of ASIV in treating renal fibrosis.

Qinling liquid ameliorates renal immune inflammatory damage via activating autophagy through AMPK/Stat3 pathway in uric acid nephropathy

BACKGROUND

Excessive deposition of uric acid (UA) is one of the risk factors for kidney damage. Qinling liquid (QL) has a certain therapeutic effect on uric acid nephropathy (UAN), but its regulation mechanism is still unclear.

METHODS

UAN rat models and UA induced rat renal tubular epithelial cells (NRK-52E) were constructed to evaluate the functional roles of QL. We firstly evaluated the kidney function and the degree of kidney damage in rats after QL treatment. Then, effects of QL on autophagy and NLRP3 inflammasome activation were assessed. Moreover, the regulation of QL in AMPK and Stat3 phosphorylation levels and the relationship among autophagy, AMPK/Stat3 pathway and NLRP3 inflammasomes were determined.

RESULTS

QL could alleviate the inflammatory damage in UAN rats and promote the activation of autophagy. In addition, QL suppressed UA-induced activation of NLRP3 inflammasomes in rat renal tubular epithelial cells, which was partially reversed by autophagy inhibitor. Further, AMPK/Stat3 axis-mediated autophagy participated in the regulation of UA-induced NLRP3 inflammasome activation in NRK-52E cells. Finally, we confirmed that inhibiting AMPK/Stat3 pathway partly deteriorated the ameliorating effect of QL on renal immune inflammatory injury in UAN rats.

CONCLUSION

Through in vivo and in vitro experiments, we found that QL promotes autophagy by activating the AMPK/Stat3 pathway, thereby improving renal immune inflammatory injury in UAN.

Sodium Butyrate Attenuates AGEs-Induced Oxidative Stress and Inflammation by Inhibiting Autophagy and Affecting Cellular Metabolism in THP-1 Cells

In recent years, sodium butyrate has gained increased attention for its numerous beneficial properties. However, whether sodium butyrate could alleviate inflammatory damage by macrophage activation and its underlying mechanism remains unclear. The present study used an advanced glycosylation products- (AGEs-) induced inflammatory damage model to study whether sodium butyrate could alleviate oxidative stress, inflammation, and metabolic dysfunction of human monocyte-macrophage originated THP-1 cells in a PI3K-dependent autophagy pathway. The results indicated that sodium butyrate alleviated the AGEs-induced oxidative stress, decreased the level of reactive oxygen species (ROS), increased malondialdehyde (MDA) and mRNA expression of pro-inflammatory cytokines of interleukin (IL)-1β and tumor necrosis factor (TNF)-α, and increased the content of superoxide dismutase (SOD). Sodium butyrate reduced the protein expression of the NLR family, pyrin domain-containing protein 3 (NLRP3) and Caspase-1, and decreased the nucleus expression of nuclear factor-kappaB (NF-κB). Sodium butyrate decreased the expression of light-chain-associated protein B (LC3B) and Beclin-1, and inhibited autophagy. Moreover, sodium butyrate inhibited the activation of the PI3K/Akt pathway in AGEs-induced THP-1 cells. In addition, the metabolomics analysis showed that sodium butyrate could affect the production of phosphatidylcholine, L-glutamic acid, UDP-N-acetylmuraminate, biotinyl-5'-AMP, and other metabolites. In summary, these results revealed that sodium butyrate inhibited autophagy and NLRP3 inflammasome activation by blocking the PI3K/Akt/NF-κB pathway, thereby alleviating oxidative stress, inflammation, and metabolic disorder induced by AGEs.

Histone modification in podocyte injury of diabetic nephropathy

Diabetic nephropathy (DN), an important complication of diabetic microvascular disease, is one of the leading causes of end-stage renal disease (ESRD), which brings heavy burdens to the whole society. Podocytes are terminally differentiated glomerular cells, which act as a pivotal component of glomerular filtration barrier. When podocytes are injured, glomerular filtration barrier is damaged, and proteinuria would occur. Dysfunction of podocytes contributes to DN. And degrees of podocyte injury influence prognosis of DN. Growing evidences have shown that epigenetics does a lot in the evolvement of podocyte injury. Epigenetics includes DNA methylation, histone modification, and non-coding RNA. Among them, histone modification plays an indelible role. Histone modification includes histone methylation, histone acetylation, and other modifications such as histone phosphorylation, histone ubiquitination, histone ADP-ribosylation, histone crotonylation, and histone β-hydroxybutyrylation. It can affect chromatin structure and regulate gene transcription to exert its function. This review is to summarize documents about pathogenesis of podocyte injury, most importantly, histone modification of podocyte injury in DN recently to provide new ideas for further molecular research, diagnosis, and treatment.

Autophagy in renal fibrosis: Protection or promotion?

Autophagy is a process that degrades endogenous cellular protein aggregates and damaged organelles via the lysosomal pathway to maintain cellular homeostasis and energy production. Baseline autophagy in the kidney, which serves as a quality control system, is essential for cellular metabolism and organelle homeostasis. Renal fibrosis is the ultimate pathological manifestation of progressive chronic kidney disease. In several experimental models of renal fibrosis, different time points, stimulus intensities, factors, and molecular mechanisms mediating the upregulation or downregulation of autophagy may have different effects on renal fibrosis. Autophagy occurring in a single lesion may also exert several distinct biological effects on renal fibrosis. Thus, whether autophagy prevents or facilitates renal fibrosis remains a complex and challenging question. This review explores the different effects of the dual regulatory function of autophagy on renal fibrosis in different renal fibrosis models, providing ideas for future work in related basic and clinical research.

Liuwei Dihuang Pills Inhibit Podocyte Injury and Alleviate IgA Nephropathy by Directly Altering Mesangial Cell-Derived Exosome Function and Secretion

Background: Immunoglobulin A nephropathy (IgAN) is the most common glomerular disease worldwide. Its pathological features include IgA immune complex deposition, accompanied by mesangial cell proliferation and mesangial matrix expansion. This study was conducted to investigate the effects of Liuwei Dihuang pills (LWDHW) on IgAN in mice and human podocytes, as well as to determine their underlying mechanisms of action.

Methods: For in vitro experiments, podocytes were exposed to the human mesangial cell culture medium supernatant of glomerular cells treated with aggregated IgA1 (aIgA1) and LWDHW-containing serum. Cell viability and the proportion of positive cells were evaluated using CCK-8 and flow apoptosis kits, respectively. The cells were collected for western blot analysis. Twenty-four mice with IgAN induced by oral bovine serum albumin administration combined with tail vein injection of staphylococcal enterotoxin B were randomly divided into four groups of six mice each: untreated model group, model + LWDHW group, model + rapamycin group, and model + LWDHW + rapamycin group. The normal control group contained six mice. The red blood cell count in the urine, urine protein, blood urea nitrogen, serum creatinine, and IgA deposition were determined, and TUNEL and western blotting were performed in the mouse kidney tissues.

Results:In vitro experiments showed that LWDHW promoted autophagy by regulating the PI3K/Akt/mTOR signalling pathway and improved the damage to podocytes caused by the aIgA1-treated mesangial cell supernatant. This study demonstrates the effectiveness of LWDHW for treating IgAN. In the animal experiments, LWDHW significantly reduced the urine red blood cell count, serum creatinine and urea nitrogen contents, and 24 h urinary protein function and improved IgA deposition in the kidney tissues, glomerular volume, glomerular cell proliferation and polysaccharide deposition, and glomerular cell apoptosis. The pills also reversed the changes in the LC3II/I ratio and p62 content in the kidney tissues. The combination of LWDHW and rapamycin showed stronger inhibitory effects compared to those of LWDHW or rapamycin alone.

Conclusion: LWDHW may improve regulation of the PI3K-Akt-mTOR pathway and inhibit autophagy in podocytes, as well as alleviate IgA nephropathy by directly altering mesangial cell exosomes.

Renoprotective Roles of Curcumin

The use of herb-based therapies is increasing over the past decades. These agents have been reported to provide many beneficial effects in many experimental and clinical studies. Curcumin is one of these agents which has potent pharmacological effects enabling it for the prevent and treatment of many diseases and pathologies such as renal disorders, hyperglycemia, oxidative stress, hypertension, and dyslipidemia. However, the exact molecular mechanisms mediating these renoprotective effects of curcumin are not well established. So, in the current study, we surveyed for possible renoprotective roles of curcumin and concluded how curcumin protects against renal injuries.

The combination of dapagliflozin and statins ameliorates renal injury through attenuating the activation of inflammasome-mediated autophagy in insulin-resistant rats

Long-term use of a high-fat diet with high-fructose (HFF) intake could promote insulin resistance and induce lipid accumulation leading to kidney injury possibly via impairment of the autophagy process and enhancement of the inflammasome pathway. We investigated whether dapagliflozin as a monotherapy or combined with atorvastatin could restore kidney autophagy impairment and reduce inflammasome activation associated with kidney injury induced by HFF consumption. Male Wistar rats were given an HFF for 16 weeks and then treated with dapagliflozin with or without atorvastatin for 4 weeks. Impaired glucose tolerance, dyslipidemia, renal lipid accumulation along with impaired renal autophagy and activated inflammasome pathway promoted renal injury were exhibited in HFF rats. Dapagliflozin with or without atorvastatin treatment could partially restore disrupted metabolic parameters and reduce kidney injury. In particular, the combination treatment group showed significant amelioration of inflammasome activation and autophagy impairment. In conclusion, the combination therapy of dapagliflozin and atorvastatin has a positive effect on renal injury associated with autophagy and inflammasome activation induced by HFF in insulin-resistant rats. This study is the first report demonstrating the underlying mechanism associated with a combination treatment of dapagliflozin and atorvastatin on autophagy and inflammasome pathways in an insulin-resistant condition. Therefore, dapagliflozin in combination with atorvastatin may be a further preventive or therapeutic strategy for chronic kidney disease in an insulin-resistant or diabetic condition.

Co-culture of peripheral blood mononuclear cell (PBMC) and human coronary artery endothelial cell (HCAEC) reveals the important role of autophagy implicated in Kawasaki disease

BACKGROUND

Kawasaki disease (KD) is a systemic vasculitis syndrome that commonly occurs in children. Autophagy has been increasingly shown to be involved in various cardiovascular diseases, including endothelial dysfunction and vascular endothelial injury. However, whether autophagy is implicated in the pathogenesis of KD remains poorly understood, and particularly, how the dysfunction of human coronary artery endothelial cells (HCAECs) is associated with autophagy in peripheral blood mononuclear cells (PBMCs) from KD patients awaits further investigation.

METHODS

Peripheral blood samples were collected from KD patients, common fever patients, and healthy controls. The PBMC samples were isolated from KD blood samples collected at three different phases: the acute phase before therapy (acute-KD), 1 week (subacute-KD), and 4 weeks (convalescent-KD) after drug administration.

RESULTS

The autophagy flux was significantly increased in the PBMCs of KD patients at acute phase. The PBMCs of acute KD patients could induce autophagy in HCAECs and promote the secretion of chemokines and pro-inflammatory factors after cocultured with HCAECs whereas 3-methyladenine (3-MA) drug could partly reverse this process.

CONCLUSIONS

Autophagy is involved in the inflammatory injury of vascular endothelial cells associated with PBMCs in KD patients, and may play a crucial role in regulating inflammation. Hence, we identify a novel regulatory mechanism of vascular injury in this disease.

Therapeutic silencing of SMOC2 prevents kidney function loss in mouse model of chronic kidney disease

Chronic kidney disease (CKD) is associated with substantial morbidity and mortality. We developed a mouse model that mimics human CKD with inflammation, extracellular matrix deposition, tubulointerstitial fibrosis, increased proteinuria, and associated reduction in glomerular filtration rate over time. Using this model, we show that genetic deficiency of SMOC2 or therapeutic silencing of SMOC2 with small interfering RNAs (siRNAs) after disease onset significantly ameliorates inflammation, fibrosis, and kidney function loss. Mechanistically, we found that SMOC2 promotes fibroblast to myofibroblast differentiation by activation of diverse cellular signaling pathways including MAPKs, Smad, and Akt. Thus, targeting SMOC2 therapeutically offers an approach to prevent fibrosis progression and CKD after injury.

RIP3 impedes transcription factor EB to suppress autophagic degradation in septic acute kidney injury

Autophagy is an important renal-protective mechanism in septic acute kidney injury (AKI). Receptor interacting protein kinase 3 (RIP3) has been implicated in the renal tubular injury and renal dysfunction during septic AKI. Here we investigated the role and mechanism of RIP3 on autophagy in septic AKI. We showed an activation of RIP3, accompanied by an accumulation of the autophagosome marker LC3II and the autophagic substrate p62, in the kidneys of lipopolysaccharide (LPS)-induced septic AKI mice and LPS-treated cultured renal proximal tubular epithelial cells (PTECs). The lysosome inhibitor did not further increase the levels of LCII or p62 in LPS-treated PTECs. Moreover, inhibition of RIP3 attenuated the aberrant accumulation of LC3II and p62 under LPS treatment in vivo and in vitro. By utilizing mCherry-GFP-LC3 autophagy reporter mice in vivo and PTECs overexpression mRFP-GFP-LC3 in vitro, we observed that inhibition of RIP3 restored the formation of autolysosomes and eliminated the accumulated autophagosomes under LPS treatment. These results indicated that RIP3 impaired autophagic degradation, contributing to the accumulation of autophagosomes. Mechanistically, the nuclear translocation of transcription factor EB (TFEB), a master regulator of the lysosome and autophagy pathway, was inhibited in LPS-induced mice and LPS-treated PTECs. Inhibition of RIP3 restored the nuclear translocation of TFEB in vivo and in vitro. Co-immunoprecipitation further showed an interaction of RIP3 and TFEB in LPS-treated PTECs. Also, the expression of LAMP1 and cathepsin B, two potential target genes of TFEB involved in lysosome function, were decreased under LPS treatment in vivo and in vitro, and this decrease was rescued by inhibiting RIP3. Finally, overexpression of TFEB restored the autophagic degradation in LPS-treated PTECs. Together, the present study has identified a pivotal role of RIP3 in suppressing autophagic degradation through impeding the TFEB-lysosome pathway in septic AKI, providing potential therapeutic targets for the prevention and treatment of septic AKI.

Protective impact of Spirulina platensis against γ-irradiation and thioacetamide-induced nephrotoxicity in rats mediated by regulation of micro-RNA 1 and micro-RNA 146a

Chronic kidney disease develops popular and medical health problems, especially in developing countries. The objective of this study is to investigate the protective mechanism of Spirulina platensis against γ-irradiation (R) and/or thioacetamide (TAA)-induced nephrotoxicity in rats. Rats intoxicated with R or TAA showed alterations in kidney function markers (urea, creatinine, albumin, and total protein contents), oxidative stress markers (malondialdehyde, reduced glutathione), antioxidant enzymes (superoxide dismutase, catalase), and several inflammatory markers (including, the high-sensitivity C-reactive protein, hypoxia-inducible factor-1 alpha, tumor necrosis factor-alpha, interferon-gamma, some interleukins, and nuclear factor-kappa B). Rats also acquired apoptosis, evinced by high caspase-3 efficacy. This nephrotoxicity mediated by upregulation of the messenger RNA (mRNA) gene expression of the autophagy markers: Beclin-1, microtubule-associated protein LC3, p62 binding protein, immunoglobulin G receptor Fcγ receptor (FcγR), micro-RNA-1 (miR-1), protein expression of phospho-adenosine monophosphate-activated protein kinase, and phospho-mammalian target of rapamycin, along with downregulation of miR-146a mRNA gene expression and alteration of calcium and iron levels. The combined treatment R/TAA enhanced the observed oxidative stress, inflammation, apoptosis, and autophagy that mediated by higher upregulation of miR-1 and downregulation of miR-146a mRNA gene expression. Spirulina platensis administration exhibited a nephroprotective impact on R, TAA, and R/TAA toxicities via regulating miR-1 and miR-146a mRNA gene expression that monitored adenosine monophosphate-activated protein kinase/mammalian target of rapamycin signaling.

Hyperuricemia causes kidney damage by promoting autophagy and NLRP3-mediated inflammation in rats with urate oxidase deficiency

Epidemiological research has shown that elevated serum urate concentration is a risk factor for the development of kidney disease; however, the mechanisms underlying this process have not yet been elucidated. To examine the role of urate in the kidney, we used Wistar rats to functionally disrupt expression of urate oxidase (UOX) by using the CRISPR/Cas9 system. In comparison to wild-type (WT) rats, serum urate levels spontaneously and persistently increased in UOX-KO rats, without showing a significant decrease in survival rate. Architecture and function of the kidneys in UOX-KO rats were impaired. Injury to the kidney resulted in increased interstitial fibrosis, macrophage infiltration, increased expression of NLRP3 and IL-1β, and activation of multiple cell-signaling pathways associated with autophagy, such as AMPK, p38 MAPK, ERK and JNK pathways. Inhibition of autophagy with the PI3K inhibitor 3-MA abrogated the development of kidney damage and attenuated renal fibrosis, macrophage infiltration, and expression of NLRP3 and IL-1β in injured kidneys. In conclusion, the UOX-KO rat is a great model to study hyperuricemia-related diseases. Hyperuricemia-induced autophagy and NLRP3-dependent inflammation are critically involved in the development of renal damage and, therefore, highlight the inhibition of autophagy and inflammation in search of therapeutic strategies to treat uric acid nephropathy.

Mechanisms of mTOR and Autophagy in Human Endothelial Cell Infected with Dengue Virus-2

The mechanistic mammalian target of rapamycin (mTOR) plays a crucial role in response to many major cellular processes, including cellular metabolism, proliferation, and autophagy. Both mTOR and autophagy are suggested to be involved in the viral infection. However, little is known about the role of mTOR and autophagy in human endothelial cell infected with dengue virus-2 (DENV-2), this study is to investigate the role of mTOR and autophagy in human umbilical vein endothelial cells (HUVECs) infected with DENV-2 and related regulatory mechanisms. HUVECs were cultured in epithelial cell medium. A series of experiments involving immunohistochemistry, TCID50 method, real-time PCR, western blot, and laser confocal were performed in this study. The cell line was identified as HUVEC by the expression of cell factor VIII. The expression level of DENV-2 mRNA increased and showed an upward trend. Compared with the control group, the fluorescence of autophagy-labeled protein LC3B and lysosome-labeled protein lysosome-associated membrane protein 1 (LAMP1) in the cytoplasm of HUVEC induced by rapamycin was observed, and intensity was significantly enhanced under confocal laser scanning microscope, after fluorescence synthesis, the fluorescence of autophagy-labeled protein LC3B and lysosome-labeled protein LAMP1 overlaps were reduced. The intensity of fluorescence of autophagy-labeled protein LC3B and lysosome-labeled protein LAMP1 increased in 1 × 104 TCID50 DENV-2 infection group, after fluorescence synthesis, fluorescence of autophagy-labeled protein LC3B, lysosome-labeled protein LAMP1, and DEN2 NS1 overlapped. Compared with the control group, the phosphorylation level of mTOR, Atg13, and p-ULK1 in DENV-2-infected group or Rapa treatment group decreased significantly (p < 0.05), and the level of LC3-II increased significantly (p < 0.05). These results suggest that DENV-2 induces autophagy in HUVECs through mTOR signaling molecule.

Delayed treatment with an autophagy inhibitor 3-MA alleviates the progression of hyperuricemic nephropathy

Autophagy is a cell self-renewal process that relies on the degradation of the cytoplasmic proteins or organelles of lysosomes and is associated with development of numerous diseases. However, the therapeutic effect of autophagy inhibition on hyperuricemic nephropathy (HN) and the underlying mechanisms are still unknown. Here, we investigated the effect of delayed treatment with 3-methyladenine (3-MA), a specific autophagy inhibitor, on the development of HN in a rat model. Administration of 3-MA at 21 days following after uric acid injury protected kidney from hyperuricemic-related injuries, as demonstrated by improving renal dysfunction and architecture damage, blocking Beclin-1 and LC3II/I and decreasing the number of autophagic vacuoles. Late treatment with 3-MA was also effective in attenuating renal fibrosis as evidenced by reducing ECM protein deposition, blocking epithelial-to-mesenchymal transition (EMT) and decreasing the number of renal epithelial cells arrested at the G2/M phase of cell cycle. Injury to the kidney resulted in increased expression of TGFβ receptor I, and phosphorylation of Smad3, 3-MA significantly abrogated all these responses. Moreover, inhibition of autophagy suppressed mitochondrial fission, downregulated the expression of Dynamin-related protein 1 (Drp-1), Cofilin and F-actin, and alleviated cell apoptosis. Finally, 3-MA effectively blocked STAT3 and NF-κB phosphorylation and suppressed infiltration of macrophages and lymphocytes as well as release of multiple profibrogenic cytokines/chemokines in the injured kidney. Taken together, these findings indicate that hyperuricemia-induced autophagy is critically involved in the activation of renal fibroblasts, EMT, mitochondrial fission and apoptosis of tubular epithelial cells and development of renal fibrosis. Thus, this study provides evidence for autophagy inhibitors as the treatment of HN patients.

Crosstalk between tubular epithelial cells and glomerular endothelial cells in diabetic kidney disease

In recent years, although the development of clinical therapy for diabetic kidney disease (DKD) has made great progress, the progression of DKD still cannot be controlled. Therefore, further study of the pathogenesis of DKD and improvements in DKD treatment are crucial for prognosis. Traditional studies have shown that podocyte injury plays an important role in this process. Recently, it has been found that glomerulotubular balance and tubuloglomerular feedback (TGF) may be involved in the progression of DKD. Glomerulotubular balance is the specific gravity absorption of the glomerular ultrafiltrate by the proximal tubules, which absorbs only 65% to 70% of the ultrafiltrate. This ensures that the urine volume will not change much regardless of whether the glomerular filtration rate (GFR) increases or decreases. TGF is one of the significant mechanisms of renal blood flow and self-regulation of GFR, but how they participate in the development of DKD in the pathological state and the specific mechanism is not clear. Injury to tubular epithelial cells (TECs) is the key link in DKD. Additionally, injury to glomerular endothelial cells (GECs) plays a key role in the early occurrence and development of DKD. However, TECs and GECs are close to each other in anatomical position and can crosstalk with each other, which may affect the development of DKD. Therefore, the purpose of this review was to summarize the current knowledge on the crosstalk between TECs and GECs in the pathogenesis of DKD and to highlight specific clinical and potential therapeutic strategies.

Yiqihuoxue Formula Activates Autophagy and Offers Renoprotection in a Rat Model of Adenine-Induced Kidney Disease

Chronic kidney disease (CKD) is a worldwide health problem for which effective therapeutic methods are still lacking. Traditional Chinese medicine (TCM) has been indicated as an effective alternative treatment for kidney disease. In this study, a clinically effective therapy, yiqihuoxue (YQHX) formula, was administrated to adenine-induced kidney disease rats for 6 weeks. We found that the adenine rats displayed a significant reduction in renal function as evidenced by the increased levels of serum creatinine (Scr), blood urea nitrogen (BUN), and 24-h urinary albumin level, which were attenuated by the YQHX treatment. The glomerulosclerosis, interstitial fibrosis, arteriolosclerosis, interstitial inflammation, and tubular dilatation were reversed by the YQHX treatment in the adenine rats. Furthermore, the hepatic damage characterized by increased levels of aspartate aminotransferase and alanine aminotransferase and inflammatory cell infiltration was improved by YQHX. In addition, the number of apoptotic cells in the adenine rats was obviously reduced by the YQHX treatment as manifested by the lower expression level of cleaved caspase-3 protein. Moreover, the YQHX treatment downregulated the expression levels of fibronectin, type I collagen, α-smooth muscle actin, and TGF-β1 in the adenine rats. Furthermore, autophagy was activated by the YQHX treatment, which manifested as an increased LC3-II and Beclin-1 expression levels and a decreased p62 level. In conclusion, the YQHX formula might retard the progression of kidney disease by activating autophagy.

Research Progress on the Pathological Mechanisms of Podocytes in Diabetic Nephropathy

Diabetic nephropathy (DN) is not only an important microvascular complication of diabetes but also the main cause of end-stage renal disease. Studies have shown that the occurrence and development of DN are closely related to morphological and functional changes in podocytes. A series of morphological changes after podocyte injury in DN mainly include podocyte hypertrophy, podocyte epithelial-mesenchymal transdifferentiation, podocyte detachment, and podocyte apoptosis; functional changes mainly involve podocyte autophagy. More and more studies have shown that multiple signaling pathways play important roles in the progression of podocyte injury in DN. Here, we review research progress on the pathological mechanism of morphological and functional changes in podocytes associated with DN, to provide a new target for delaying the occurrence and development of this disorder.

Diabetic Nephropathy Assessment: Microtubule-Associated Protein 1 Light-Chain 3B a New Promising Biomarker

Autophagy is a highly conserved pathway. Impairment of autophagy is implicated in the pathogenesis of diabetic nephropathy. The current study applied a bioinformatics analysis to retrieve promising autophagy biomarker relevant diabetic nephropathy. Urinary expression of Microtubule-associated protein 1 light-chain 3B (LC3B) RNA was assessed. Urine samples of 86 type II diabetic kidney disease Egyptian patients (albuminuria group) were provided to quantify urinary expression of LC3B. A group of 30 healthy volunteers were also enrolled in addition to non-albuminuria group including 44 patients. Our study revealed a cut-off value for urinary LC3B expression level that was calculated by receiver-operating characteristic curve as 0.866. Sensitivity and specificity of LC3B were 83.7 and 78.4% respectively. The positivity rate of urinary LC3B expression level was significantly lower in diabetic nephropathy patients than control group. LC3B has great clinical value as promising biomarker in diabetic nephropathy assessment.

Autophagy in Kidney Disease

Autophagy is a cellular homeostatic program for the turnover of cellular organelles and proteins, in which double-membraned vesicles (autophagosomes) sequester cytoplasmic cargos, which are subsequently delivered to the lysosome for degradation. Emerging evidence implicates autophagy as an important modulator of human disease. Macroautophagy and selective autophagy (e.g., mitophagy, aggrephagy) can influence cellular processes, including cell death, inflammation, and immune responses, and thereby exert both adaptive and maladaptive roles in disease pathogenesis. Autophagy has been implicated in acute kidney injury, which can arise in response to nephrotoxins, sepsis, and ischemia/reperfusion, and in chronic kidney diseases. The latter includes comorbidities of diabetes and recent evidence for chronic obstructive pulmonary disease-associated kidney injury. Roles of autophagy in polycystic kidney disease and kidney cancer have also been described. Targeting the autophagy pathway may have therapeutic benefit in the treatment of kidney disorders.

Molecular Interactions Between Reactive Oxygen Species and Autophagy in Kidney Disease

Reactive oxygen species (ROS) are highly reactive signaling molecules that maintain redox homeostasis in mammalian cells. Dysregulation of redox homeostasis under pathological conditions results in excessive generation of ROS, culminating in oxidative stress and the associated oxidative damage of cellular components. ROS and oxidative stress play a vital role in the pathogenesis of acute kidney injury and chronic kidney disease, and it is well documented that increased oxidative stress in patients enhances the progression of renal diseases. Oxidative stress activates autophagy, which facilitates cellular adaptation and diminishes oxidative damage by degrading and recycling intracellular oxidized and damaged macromolecules and dysfunctional organelles. In this review, we report the current understanding of the molecular regulation of autophagy in response to oxidative stress in general and in the pathogenesis of kidney diseases. We summarize how the molecular interactions between ROS and autophagy involve ROS-mediated activation of autophagy and autophagy-mediated reduction of oxidative stress. In particular, we describe how ROS impact various signaling pathways of autophagy, including mTORC1-ULK1, AMPK-mTORC1-ULK1, and Keap1-Nrf2-p62, as well as selective autophagy including mitophagy and pexophagy. Precise elucidation of the molecular mechanisms of interactions between ROS and autophagy in the pathogenesis of renal diseases may identify novel targets for development of drugs for preventing renal injury.

Autophagy and senescence: A new insight in selected human diseases

Senescence and autophagy play important roles in homeostasis. Cellular senescence and autophagy commonly cause several degenerative processes, including oxidative stress, DNA damage, telomere shortening, and oncogenic stress; hence, both events are known to be interrelated. Autophagy is well known for its disruptive effect on human diseases, and it is currently proposed to have a direct effect on triggering senescence and quiescence. However, it is yet to be proven whether autophagy has a positive or negative impact on senescence. It is known that elevated levels of autophagy induce cell death, whereas inadequate autophagy can trigger cellular senescence. Both have important roles in human diseases such as aging, renal degeneration, neurodegenerative disorders, and cancer. Therefore, this review aims to highlight the relevance of senescence and autophagy in selected human ailments through a summary of recent findings on the connection and effects of autophagy and senescence in these diseases.

Autophagy: A Lysosome-Dependent Process with Implications in Cellular Redox Homeostasis and Human Disease

SIGNIFICANCE

Autophagy, a lysosome-dependent homeostatic process inherent to cells and tissues, has emerging significance in the pathogenesis of human disease. This process enables the degradation and turnover of cytoplasmic substrates via membrane-dependent sequestration in autophagic vesicles (autophagosomes) and subsequent lysosomal delivery of cargo. Recent Advances: Selective forms of autophagy can target specific substrates (e.g., organelles, protein aggregates, and lipids) for processing. Autophagy is highly regulated by oxidative stress, including exposure to altered oxygen tension, by direct and indirect mechanisms, and contributes to inducible defenses against oxidative stress. Mitochondrial autophagy (mitophagy) plays a critical role in the oxidative stress response, through maintenance of mitochondrial integrity.

CRITICAL ISSUES

Autophagy can impact a number of vital cellular processes including inflammation and adaptive immunity, host defense, lipid metabolism and storage, mitochondrial homeostasis, and clearance of aggregated proteins, all which may be of significance in human disease. Autophagy can exert both maladaptive and adaptive roles in disease pathogenesis, which may also be influenced by autophagy impairment. This review highlights the essential roles of autophagy in human diseases, with a focus on diseases in which oxidative stress or inflammation play key roles, including human lung, liver, kidney and heart diseases, metabolic diseases, and diseases of the cardiovascular and neural systems.

FUTURE DIRECTIONS

Investigations that further elucidate the complex role of autophagy in the pathogenesis of disease will facilitate targeting this pathway for therapies in specific diseases.

Metformin: A Candidate Drug for Renal Diseases

Over the past decades metformin has been the optimal first-line treatment for type 2 diabetes mellitus (T2DM). Only in the last few years, it has become increasingly clear that metformin exerts benign pleiotropic actions beyond its prescribed use and ongoing investigations focus on a putative beneficial impact of metformin on the kidney. Both acute kidney injury (AKI) and chronic kidney disease (CKD), two major renal health issues, often result in the need for renal replacement therapy (dialysis or transplantation) with a high socio-economic impact for the patients. Unfortunately, to date, effective treatment directly targeting the kidney is lacking. Metformin has been shown to exert beneficial effects on the kidney in various clinical trials and experimental studies performed in divergent rodent models representing different types of renal diseases going from AKI to CKD. Despite growing evidence on metformin as a candidate drug for renal diseases, in-depth research is imperative to unravel the molecular signaling pathways responsible for metformin's renoprotective actions. This review will discuss the current state-of-the-art literature on clinical and preclinical data, and put forward potential cellular mechanisms and molecular pathways by which metformin ameliorates AKI/CKD.

Pharmacological inhibition of autophagy by 3-MA attenuates hyperuricemic nephropathy

Autophagy has been identified as a cellular process of bulk degradation of cytoplasmic components and its persistent activation is critically involved in the renal damage induced by ureteral obstruction. However, the role and underlying mechanisms of autophagy in hyperuricemic nephropathy (HN) remain unknown. In the present study, we observed that inhibition of autophagy by 3-methyladenine (3-MA) abolished uric acid-induced differentiation of renal fibroblasts to myofibroblasts and activation of transforming growth factor-β1 (TGF-β1), epidermal growth factor receptor (EGFR), and Wnt signaling pathways in cultured renal interstitial fibroblasts. Treatment with 3-MA also abrogated the development of HN in vivo as evidenced by improving renal function, preserving renal tissue architecture, reducing the number of autophagic vacuoles, and decreasing microalbuminuria. Moreover, 3-MA was effective in attenuating renal deposition of extracellular matrix (ECM) proteins and expression of α-smooth muscle actin (α-SMA) and reducing renal epithelial cells arrested at the G₂/M phase of cell cycle. Injury to the kidney resulted in increased expression of TGF-β1 and TGFβ receptor I, phosphorylation of Smad3 and TGF-β-activated kinase 1 (TAK1), and activation of multiple cell signaling pathways associated with renal fibrogenesis, including Wnt, Notch, EGFR, and nuclear factor-κB (NF-κB). 3-MA treatment remarkably inhibited all these responses. In addition, 3-MA effectively suppressed infiltration of macrophages and lymphocytes as well as release of multiple profibrogenic cytokines/chemokines in the injured kidney. Collectively, these findings indicate that hyperuricemia-induced autophagy is critically involved in the activation of renal fibroblasts and development of renal fibrosis and suggest that inhibition of autophagy may represent a potential therapeutic strategy for HN.

Aquaporin 5 is degraded by autophagy in diabetic submandibular gland

Autophagy is a catabolic process which is involved in the development of many diseases including diabetes mellitus and its complications. Hyposalivation is a common complication of diabetes mellitus, whereas its mechanism remains unclear. Here, we observed that the stimulated salivary flow rate of SMG was significantly decreased in db/db mice, a diabetic mice model. The expressions of aquaporin 5 (AQP5), a water channel protein, were decreased, whereas the mRNA level of AQP5 was increased in SMGs of both diabetic patients and mice. Under transmission electron microcope, more autophagosomes were detected in diabetic SMGs. Expressions of autophagy related proteins LC3II, Beclin-1 and ATG5 were increased, meanwhile autophagy substrate p62 was decreased in SMGs of diabetic patients and mice, indicating that autophagy was activated in diabetic SMG. Double immunofluorescence staining showed that the colocalization of AQP5 and LC3 was increased in SMGs of diabetic mice. In cultured SMG-C6 cells, high glucose (HG), but not high osmotic pressure, reduced AQP5 protein expression and induced autophagy. Moreover, inhibition of autophagy by 3-methyladenin, an autophagy inhibitor, or by autophagy-related gene 5 siRNA, decreased HG-induced AQP5 reduction in SMG-C6 cells. Additionally, the expression of p-p85, p-Akt and p-mTOR were decreased in HG-treated SMG-C6 cells. Pretreatment with 740Y-P, a PI3K agonist, significantly suppressed HG-induced autophagy and AQP5 degradation. Taken together, these results indicate that autophagy plays a crucial role in AQP5 degradation in diabetic SMG via PI3K/Akt/mTOR signaling pathway, which contributes to the dysfunction of diabetic SMG. Our study provides a novel mechanism of diabetic hyposalivation.

ROS-Autophagy pathway mediates monocytes-human umbilical vein endothelial cells adhesion induced by apelin-13

Apelin is the endogenous ligand of APJ receptor. Both monocytes (MCs) and human umbilical vein endothelial cells (HUVECs) express apelin and APJ, which play important roles in the physiological processes of atherosclerosis. Our previous research indicated that apelin-13 promoted MCs-HUVECs adhesion. Here, we further explore the mechanism responsible for MCs-HUVECs adhesion induced by apelin-13. Apelin-13 promoted reactive oxygen species (ROS) generation and NOX4 expression in HUVECs. Apelin-13 inducedautophagy, increased proteins beclin1 and LC3-II/I expression and induced autophagy flux in HUVECs, which was blocked by NAC, catalase and DPI. Autophagy flux induced by apelin-13 was inhibited by NAC and catalase but not hydroxychloroquine (HCQ). NAC, catalase, and DPI prevented apelin-13 induced ICAM-1 expression in HUVECs. Rapamycin enhanced MCs-HUVECs adhesion that was reversed by NAC, catalase, and DPI. Down-regulation of beclin1 and LC3 by siRNA blocked MCs-HUVECs adhesion. Apelin-13 induced atherosclerotic plaque and increased NOX4, LC3-II/I expression in ApoE-/-(HFD) mouse model. Our results demonstrated that apelin-13 induced MCs-HUVECs adhesion via a ROS-autophagy pathway.

Beneficial Effects of Resveratrol-Mediated Inhibition of the mTOR Pathway in Spinal Cord Injury

Spinal cord injury (SCI) causes a high rate of morbidity and disability. The clinical features of SCI are divided into acute, subacute, and chronic phases according to its pathophysiological events. The mammalian target of rapamycin (mTOR) signaling pathway plays an important role in cell death and inflammation in the acute phase and neuroregeneration in the subacute/chronic phases at different times. Resveratrol has the potential of regulating cell growth, proliferation, metabolism, and angiogenesis through the mTOR signaling pathway. Herein, we explicate the role of resveratrol in the repair of SCI through the inhibition of the mTOR signaling pathway. The inhibition of the mTOR pathway by resveratrol has the potential of serving as a neuronal restorative mechanism following SCI.

Blockade of histone deacetylase 6 protects against cisplatin-induced acute kidney injury

Histone deacetylase 6 (HDAC6) has been shown to be involved in various pathological conditions, including cancer, neurodegenerative disorders and inflammatory diseases. Nonetheless, its specific role in drug-induced nephrotoxicity is poorly understood. Cisplatin (dichlorodiamino platinum) belongs to an inorganic platinum - fundamental chemotherapeutic drug utilized in the therapy of various solid malignant tumors. However, the use of cisplatin is extremely limited by obvious side effects, for instance bone marrow suppression and nephrotoxicity. In the present study, we utilized a murine model of cisplatin-induced acute kidney injury (AKI) and a highly selective inhibitor of HDAC6, tubastatin A (TA), to assess the role of HDAC6 in nephrotoxicity and its associated mechanisms. Cisplatin-induced AKI was accompanied by increased expression and activation of HDAC6; blocking HDAC6 with TA lessened renal dysfunction, attenuated renal pathological changes, reduced expression of neutrophil gelatinase-associated lipocalin and kidney injury molecule 1, and decreased tubular cell apoptosis. In cultured human epithelial cells, TA or HDAC6 siRNA treatment also inhibited cisplatin-induced apoptosis. Mechanistic studies demonstrated that cisplatin treatment induced phosphorylation of AKT and loss of E-cadherin in the nephrotoxic kidney, and administration of TA enhanced AKT phosphorylation and preserved E-cadherin expression. HDAC6 inhibition also potentiated autophagy as evidenced by increased expression of autophagy-related gene (Atg) 7 (Atg7), Beclin-1, and decreased renal oxidative stress as demonstrated by up-regulation of superoxide dismutase (SOD) activity and down-regulation of malondialdehyde levels. Moreover, TA was effective in inhibiting nuclear factor-κ B (NF-κB) phosphorylation and suppressing the expression of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). Collectively, these data provide strong evidence that HDAC6 inhibition is protective against cisplatin-induced AKI and suggest that HDAC6 may be a potential therapeutic target for AKI treatment.

Resveratrol-loaded nanoparticles conjugated with kidney injury molecule-1 as a drug delivery system for potential use in chronic kidney disease

AIM

We used resveratrol (Res)-loaded nanoparticles (Res NPs) as a novel method for improving the pharmacokinetic properties of Res and analyzed the effect of Res NPs in chronic kidney disease (CKD).

MATERIALS & METHODS

We coupled anti-kidney injury molecule-1 antibodies to Res NPs and analyzed safety and efficacy.

RESULTS

Res NPs had low toxicity and induced autophagy. Res NPs inhibited the NLRP3 inflammasome and IL-1β secretion. Higher NLRP3 expression levels were observed in peripheral blood monocytic cells of CKD patients than healthy individuals. Treatment with kidney injury molecule-1-Res NPs significantly reduced creatinine and protected against tubulointerstitial injury in a murine model of CKD.

CONCLUSION

Res NPs through NLRP3 inflammasome attenuation and autophagy induction may be as a strategy to prevent CKD.

Tangshen formula attenuates diabetic renal injuries by upregulating autophagy via inhibition of PLZF expression

The Chinese herbal granule Tangshen Formula (TSF) has been proven to decrease proteinuria and improve estimated glomerular filtration rate (eGFR) in diabetic kidney disease (DKD) patients. However, the underlying mechanism of TSF on treatment of diabetic nephropathy (DN) remains unclear. The present study aimed to identify the therapeutic target of TSF in diabetic renal injuries through microarray-based gene expression profiling and establish its underlying mechanism. TSF treatment significantly attenuated diabetic renal injuries by inhibiting urinary excretion of albumin and renal histological injuries in diabetic (db/db) mice. We found that PLZF might be the molecular target of TSF in DN. In vivo, the db/db mice showed a significant increase in renal protein expression of PLZF and collagen III, and decrease in renal autophagy levels (downregulated LC3 II and upregulated p62/SQSTM1) compared to db/m mice. The application of TSF resulted in the downregulation of PLZF and collagen III and upregulation of autophagy level in the kidneys of db/db mice. In vitro, TSF reduced high glucose (HG)-induced cell proliferation for NRK52E cells. Further studies indicated that the exposure of NRK52E cells to high levels of glucose resulted in the downregulation of cellular autophagy and upregulation of collagen III protein, which was reversed by TSF treatment by decreasing PLZF expression. In conclusion, TSF might have induced cellular autophagy by inhibiting PLZF expression, which in turn resulted in an increase in autophagic degradation of collagen III that attenuated diabetic renal injuries.

Intestinal Autophagy and Its Pharmacological Control in Inflammatory Bowel Disease

Intestinal mucosal barrier, mainly composed of the intestinal mucus layer and the epithelium, plays a critical role in nutrient absorption as well as protection from pathogenic microorganisms. It is widely acknowledged that the damage of intestinal mucosal barrier or the disturbance of microorganism balance in the intestinal tract contributes greatly to the pathogenesis and progression of inflammatory bowel disease (IBD), which mainly includes Crohn’s disease and ulcerative colitis. Autophagy is an evolutionarily conserved catabolic process that involves degradation of protein aggregates and damaged organelles for recycling. The roles of autophagy in the pathogenesis and progression of IBD have been increasingly studied. This present review mainly describes the roles of autophagy of Paneth cells, macrophages, and goblet cells in IBD, and finally, several potential therapeutic strategies for IBD taking advantage of autophagy.

Podocyte Autophagy: A Potential Therapeutic Target to Prevent the Progression of Diabetic Nephropathy

Diabetic nephropathy (DN), a leading cause of end-stage renal disease (ESRD), becomes a worldwide problem. Ultrastructural changes of the glomerular filtration barrier, especially the pathological changes of podocytes, lead to proteinuria in patients with diabetes. Podocytes are major components of glomerular filtration barrier, lining outside of the glomerular basement membrane (GBM) to maintain the permeability of the GBM. Autophagy is a high conserved cellular process in lysosomes including impaired protein, cell organelles, and other contents in the cytoplasm. Recent studies suggest that activation of autophagy in podocytes may be a potential therapy to prevent the progression of DN. Here, we review the mechanisms of autophagy in podocytes and discuss the current studies about alleviating proteinuria via activating podocyte autophagy.