Fibroblast Growth Factor 2 Attenuates Renal Ischemia-Reperfusion Injury via Inhibition of Endoplasmic Reticulum Stress

Modified EBP-bFGF targeting endogenous renal extracellular matrix protects against renal ischemia-reperfusion injury in rats

Acute kidney injury (AKI) is a life-threatening disease primarily caused by renal ischemia-reperfusion (I/R) injury, which can result in renal failure. Currently, growth factor therapy is considered a promising and effective approach for AKI treatment. Basic fibroblast growth factor (bFGF), an angiogenic factor with potent activity, efficiently stimulates angiogenesis and facilitates regeneration of renal tissue. However, the unrestricted diffusion of bFGF restricts its clinical application in AKI treatment. Therefore, developing a novel sustained released system for bFGF could enhance its potential in treating AKI. In this study, we genetically engineered a multifunctional recombinant protein by fusing bFGF with a specific peptide (EBP). EBP-bFGF effectively binds to the extracellular matrix in the injured kidney, enabling slow release of bFGF in AKI. Furthermore, following orthotopic injection into I/R rats' ischemic kidneys, EBP-bFGF exhibited stable retention within the tissue. Additionally, EBP-bFGF suppressed apoptosis of renal cells, reduced renal fibrosis, and facilitated recovery of renal function. These findings suggest that EBP-bFGF delivery system represents a promising strategy for treating AKI.

Research Progress of Drug Delivery Systems Targeting the Kidneys

Chronic kidney disease (CKD) affects more than 10% of the global population, and its incidence is increasing, partially due to an increase in the prevalence of disease risk factors. Acute kidney injury (AKI) is an independent risk factor for CKD and end-stage renal disease (ESRD). The pathogenic mechanisms of CKD provide several potential targets for its treatment. However, due to off-target effects, conventional drugs for CKD typically require high doses to achieve adequate therapeutic effects, leading to long-term organ toxicity. Therefore, ideal treatments that completely cure the different types of kidney disease are rarely available. Several approaches for the drug targeting of the kidneys have been explored in drug delivery system research. Nanotechnology-based drug delivery systems have multiple merits, including good biocompatibility, suitable degradability, the ability to target lesion sites, and fewer non-specific systemic effects. In this review, the development, potential, and limitations of low-molecular-weight protein-lysozymes, polymer nanomaterials, and lipid-based nanocarriers as drug delivery platforms for treating AKI and CKD are summarized.

Erythropoietin alleviates lung ischemia-reperfusion injury by activating the FGF23/FGFR4/ERK signaling pathway

Background

The purpose of the present study was to investigate the effect of erythropoietin (EPO) on lung ischemia-reperfusion injury (LIRI).

Methods

Sprague Dawley rats and BEAS-2B cells were employed to construct an ischemia-reperfusion (I/R)-induced model in vivo and in vitro, respectively. Afterward, I/R rats and tert-butyl hydroperoxide (TBHP)-induced cells were treated with different concentrations of EPO. Furthermore, 40 patients with LIRI and healthy controls were enrolled in the study.

Results

It was observed that lung tissue damage, cell apoptosis and the expression of BAX and caspase-3 were higher in the LIRI model in vivo and in vitro than in the control group, nevertheless, the Bcl-2, FGF23 and FGFR4 expression level was lower than in the control group. EPO administration significantly reduced lung tissue damage and cell apoptosis while also up-regulating the expression of FGF23 and FGFR4. Rescue experiments indicated that EPO exerted a protective role associated with the FGF23/FGFR4/p-ERK1/2 signal pathway. Notably, the expression of serum EPO, FGF23, FGFR4 and Bcl-2 was decreased in patients with LIRI, while the expression of caspase-3 and BAX was higher.

Conclusion

EPO could effectively improve LIRI, which might be related to the activation of the FGF23/FGFR4/p-ERK1/2 signaling pathway.

Acute kidney injury: exploring endoplasmic reticulum stress-mediated cell death

Acute kidney injury (AKI) is a global health problem, given its substantial morbidity and mortality rates. A better understanding of the mechanisms and factors contributing to AKI has the potential to guide interventions aimed at mitigating the risk of AKI and its subsequent unfavorable outcomes. Endoplasmic reticulum stress (ERS) is an intrinsic protective mechanism against external stressors. ERS occurs when the endoplasmic reticulum (ER) cannot deal with accumulated misfolded proteins completely. Excess ERS can eventually cause pathological reactions, triggering various programmed cell death (autophagy, ferroptosis, apoptosis, pyroptosis). This article provides an overview of the latest research progress in deciphering the interaction between ERS and different programmed cell death. Additionally, the report consolidates insights into the roles of ERS in AKI and highlights the potential avenues for targeting ERS as a treatment direction toward for AKI.

BFGF attenuates aortic valvular interstitial cell calcification by inhibiting endoplasmic reticulum stress-mediated apoptosis

The potential protective effect of basic fibroblast growth factor (BFGF) on the cardiovascular system has been proposed previously, however, its effect on calcific aortic valve disease (CAVD) and underlying mechanisms have not been elucidated. The valvular interstitial cell (VIC) were isolated from porcine aortic valve leaflets. To investigate the effect of BFGF on osteogenic differentiation of VIC, the osteogenic induced medium (OIM) and BFGF were added. The protein expression level was detected by Western blot, and apoptosis was determined by flow cytometry. The effect of BFGF on CAVD process in vivo was assessed by a rat CAVD model, which was identified by echocardiography and Alizarin red staining. The expression level of BFGF in the aortic valve and serum were significantly upregulated in CAVD patients compared to control group. In addition, exogenous BFGF injection attenuates CAVD process in vivo. The protein markers of osteogenic differentiation, endoplasmic reticulum stress (ERS), and apoptosis were significantly upregulated by culture with OIM. On the contrary, the aforementioned proteins were suppressed after adding 100 ng/mL of BFGF. Inhibition of PI3K/Akt and ERK1/2 pathways by specific inhibitors abolished the protective effect of BFGF. In conclusion, BFGF could alleviate the VIC calcification by inhibiting ERS-mediated apoptosis, which is partly regulated by activation of the PI3K/Akt and ERK1/2 signaling pathways. BFGF may provide a potential avenue for CAVD therapy.

A single administration of FGF2 after renal ischemia-reperfusion injury alleviates post-injury interstitial fibrosis

BACKGROUND

Despite lack of clinical therapy in acute kidney injury (AKI) or its progression to chronic kidney disease (CKD), administration of growth factors shows great potential in the treatment of renal repair and further fibrosis. At an early phase of AKI, administration of exogenous fibroblast growth factor 2 (FGF2) protects against renal injury by inhibition of mitochondrial damage and inflammatory response. Here, we investigated whether this treatment attenuates the long-term renal interstitial fibrosis induced by ischemia-reperfusion (I/R) injury.

METHODS

Unilateral renal I/R with contralateral nephrectomy was utilized as an in vivo model for AKI and subsequent CKD. Rats were randomly divided into four groups: Sham-operation group, I/R group, I/R-FGF2 group and FGF2-3D group. These groups were monitored for up to 2 months. Serum creatinine, inflammatory response and renal histopathology changes were detected to evaluate the role of FGF2 in AKI and followed renal interstitial fibrosis. Moreover, the expression of vimentin, α-SMA, CD31 and CD34 were examined.

RESULTS

Two months after I/R injury, the severity of renal interstitial fibrosis was significantly attenuated in both of I/R-FGF2 group and FGF2-3D group, compared with the I/R group. The protective effects of FGF2 administration were associated with the reduction of high-mobility group box 1 (HMGB1)-mediated inflammatory response, the inhibition of transforming growth factor beta (TGF-β1)/Smads signaling-induced epithelial-mesenchymal transition and the maintenance of peritubular capillary structure.

CONCLUSIONS

A single dose of exogenous FGF2 administration 1 h or 3 days after reperfusion inhibited renal fibrogenesis and thus blocked the transition of AKI to CKD. Our findings provided novel insight into the role of FGF signaling in AKI-to-CKD progression and underscored the potential of FGF-based therapy for this devastating disease.

bFGF-like Activity Supported Tissue Regeneration, Modulated Neuroinflammation, and Rebalanced Ca2+ Homeostasis following Spinal Cord Injury

A spinal cord injury (SCI) is a well-defined debilitating traumatic event to the spinal cord that usually triggers permanent changes in motor, sensory, and autonomic functions. Injured tissue becomes susceptible to secondary mechanisms caused by SCIs, which include pro-inflammatory cytokine release, the activation of astrocytes and microglia, and increased neuronal sensibility. As a consequence, the production of factors such as GFAP, IBA-1, TNF-α, IL-1β, IFN-γ, and S100-β slow down or inhibit central nervous system (CNS) regeneration. In this regard, a thorough understanding of the mechanisms regulating the CNS, and specifically SCI, is essential for the development of new therapeutic strategies. It has been demonstrated that basic fibroblast growth factor (bFGF) was successful in the modulation of neurotrophic activity, also promoting neurite survival and tissue repair, thus resulting in the valuable care of CNS disorders. However, bFGF therapeutic use is limited due to the undesirable effects developed following its administration. Therefore, the synthetic compound mimetic of bFGF, SUN11602 (with chemical name 4-[[4-[[2-[(4-Amino-2,3,5,6-tetramethylphenyl)amino]acetyl]methylamino]-1-piperidinyl]methyl]benzamide), has been reported to show neuroprotective activities similar to those of bFGF, also demonstrating a good pharmacokinetic profile. Here, we aimed to investigate the neuroprotective activity of this bFGF-like compound in modulating tissue regeneration, neuroinflammation, and Ca2+ overload by using a subacute mouse model of SCI. SUN11602 (1, 2.5, and 5 mg/kg) was administered orally to mice for 72 h daily following the in vivo model of SCI, which was generated by the extradural compression of the spinal cord. The data obtained demonstrated that SUN11602 treatment considerably decreased motor alteration and diminished the neuroinflammatory state through the regulation of glial activation, the NF-κB pathway, and kinases. Additionally, by controlling Ca2+-binding proteins and restoring neurotrophin expression, we showed that SUN11602 therapy restored the equilibrium of the neuronal circuit. Because of these findings, bFGF-like compounds may be an effective tool for reducing inflammation in SCI patients while enhancing their quality of life.

Fibroblast growth factor 2 reduces endoplasmic reticulum stress and apoptosis in in-vitro Non-Alcoholic Fatty Liver Disease model

PURPOSE

Non-Alcoholic fatty liver disease is characterized by the accumulation of excess fat in the liver, chronic inflammation, and cell death, ranging from simple steatosis to fibrosis, and finally leads to cirrhosis and hepatocellular carcinoma. The effect of Fibroblast growth factor 2 on apoptosis and ER stress inhibition has been investigated in many studies. In this study, we aimed to investigate the effect of FGF2 on the NAFLD in-vitro model in the HepG2 cell line.

METHODS

The in-vitro NAFLD model was first induced on the HepG2 cell line using oleic acid and palmitic acid for 24 h and evaluated by ORO staining and Real-time PCR. The cell line was then treated with various concentrations of fibroblast growth factor 2 for 24 h, total RNA was extracted and cDNA was consequently synthesized. Real-time PCR and flow cytometry was applied to evaluate gene expression and apoptosis rate, respectively.

RESULTS

It was shown that fibroblast growth factor 2 ameliorated apoptosis in the NAFLD in-vitro model by reducing the expression of genes involved in the intrinsic apoptosis pathway, including caspase 3 and 9. Moreover, endoplasmic reticulum stress was decreased following upregulating the protective ER-stress genes, including SOD1 and PPARα.

CONCLUSIONS

FGF2 significantly reduced ER stress and intrinsic apoptosis pathway. Our data suggest that FGF2 treatment could be a potential therapeutic strategy for NAFLD.

PERK-STING-RIPK3 pathway facilitates cognitive impairment by inducing neuronal necroptosis in sepsis-associated encephalopathy

AIMS

Sepsis-associated encephalopathy (SAE) is a common but serious complication in septic survivors and often causes long-term cognitive impairments. The role of RIPK3-participated necroptosis in SAE remains obscured. STING is a key molecule in regulating necroptosis and apoptosis. However, there is uncertainty as to the mechanisms of STING in CLP-induced SAE. The aim of this study was to investigate whether STING is involved in the underlying mechanism of SAE.

METHODS

The contextual fear conditioning test (CFCT) assesses cognitive impairment. A transmission electron microscope (TEM) was used to notice the necroptosis. Western blotting and immunofluorescence labeling were applied for the observation of related proteins.

RESULTS

The phosphorylated STING in the hippocampal neuron of SAE mice was significantly elevated. Knocking down STING inhibited necroptosis and attenuated cognitive impairment in SAE mice. Moreover, RIPK3^-/- mice had less cognitive deficit in the SAE model. However, STING overexpression did not deteriorate cognitive impairment in RIPK3^-/- mice with SAE, indicating that STING is upstream involved in necroptosis. Furthermore, PERK inhibition ameliorated cognitive deficits through a STING-dependent pathway in SAE mice.

CONCLUSION

PERK-STING-RIPK3 pathway facilitates cognitive impairment by inducing neuronal necroptosis in the pathology of SAE, which provided a new therapeutic target in SAE treatment.

Arsenite Exposure to Human RPCs (HRTPT) Produces a Reversible Epithelial Mesenchymal Transition (EMT): In-Vitro and In-Silico Study

The human kidney is known to possess renal progenitor cells (RPCs) that can assist in the repair of acute tubular injury. The RPCs are sparsely located as single cells throughout the kidney. We recently generated an immortalized human renal progenitor cell line (HRTPT) that co-expresses PROM1/CD24 and expresses features expected on RPCs. This included the ability to form nephrospheres, differentiate on the surface of Matrigel, and undergo adipogenic, neurogenic, and osteogenic differentiation. These cells were used in the present study to determine how the cells would respond when exposed to nephrotoxin. Inorganic arsenite (iAs) was chosen as the nephrotoxin since the kidney is susceptible to this toxin and there is evidence of its involvement in renal disease. Gene expression profiles when the cells were exposed to iAs for 3, 8, and 10 passages (subcultured at 1:3 ratio) identified a shift from the control unexposed cells. The cells exposed to iAs for eight passages were then referred with growth media containing no iAs and within two passages the cells returned to an epithelial morphology with strong agreement in differential gene expression between control and cells recovered from iAs exposure. Results show within three serial passages of the cells exposed to iAs there was a shift in morphology from an epithelial to a mesenchymal phenotype. EMT was suggested based on an increase in known mesenchymal markers. We found RPCs can undergo EMT when exposed to a nephrotoxin and undergo MET when the agent is removed from the growth media.

ER stress and inflammation crosstalk in obesity

The endoplasmic reticulum (ER) governs the proper folding of polypeptides and proteins through various chaperones and enzymes residing within the ER organelle. Perturbation in the ER folding process ensues when overwhelmed protein folding exceeds the ER handling capacity, leading to the accumulation of misfolded/unfolded proteins in the ER lumen-a state being referred to as ER stress. In turn, ER stress induces a gamut of signaling cascades, termed as the "unfolded protein response" (UPR) that reinstates the ER homeostasis through a panel of gene expression modulation. This type of UPR is usually deemed "adaptive UPR." However, persistent or unresolved ER stress hyperactivates UPR response, which ultimately, triggers cell death and inflammatory pathways, termed as "maladaptive/terminal UPR." A plethora of evidence indicates that crosstalks between ER stress (maladaptive UPR) and inflammation precipitate obesity pathogenesis. In this regard, the acquisition of the mechanisms linking ER stress to inflammation in obesity might unveil potential remedies to tackle this pathological condition. Herein, we aim to elucidate key mechanisms of ER stress-induced inflammation in the context of obesity and summarize potential therapeutic strategies in the management of obesity through maneuvering ER stress and ER stress-associated inflammation.

Cyanidin-3-O-glucoside plays a protective role against renal ischemia/ reperfusion injury via the JAK/STAT pathway

PURPOSE

To investigate the role of cyanidin-3-O-glucoside (C3G) in renal ischemia/reperfusion (I/R) injury and the potential mechanisms.

METHODS

Mouse models were established by clamping the left renal vessels, and in vitro cellular models were established by hypoxic reoxygenation.

RESULTS

Renal dysfunction and tissue structural damage were significantly higher in the I/R group. After treatment with different concentrations of C3G, the levels of renal dysfunction and tissue structural damage decreased at different levels. And its protective effect was most pronounced at 200 mg/kg. The use of C3G reduced apoptosis as well as the expression of endoplasmic reticulum stress (ERS)-related proteins. Hypoxia/reoxygenation (H/R)-induced apoptosis and ERS are dependent on oxidative stress in vitro. In addition, both AG490 and C3G inhibited the activation of JAK/STAT pathway and attenuated oxidative stress, ischemia-induced apoptosis and ERS.

CONCLUSIONS

The results demonstrated that C3G blocked renal apoptosis and ERS protein expression by preventing reactive oxygen species (ROS) production after I/R via the JAK/STAT pathway, suggesting that C3G may be a potential therapeutic agent for renal I/R injury.

Safranal Treatment Induces Sirt1 Expression and Inhibits Endoplasmic Reticulum Stress in Mouse Chondrocytes and Alleviates Osteoarthritis Progression in a Mouse Model

Osteoarthritis (OA) is an age-related degenerative disease. Oxidative stress (OS) modulates OA pathogenesis by enhancing chondrocyte apoptosis and extracellular matrix (ECM) degeneration via activation of the endoplasmic reticulum (ER) stress. Prior studies revealed that safranal plays a critical role in multiple diseases treatments, but there are no reports on its effect on OA. Therefore, investigating the effect of safranal on OA is needed. As a compound that can lead excessive reactive oxygen species (ROS) accumulation, tert-butyl hydroperoxide (TBHP) was used to induce OS and OS-mediated endoplasmic reticulum (ER) stress for imitating OA in vitro. Besides, the bilateral medial meniscus was removed to induce joint instability and excessive friction of the joint surface to establish destabilization of medial meniscus for imitating the initiation and progression of OA in vivo. We, next, conducted Western blot and RT-PCR analyses to identify biomarkers of the underlying signaling pathway. Our results demonstrated that 30 μM safranal strongly upregulated Sirt1 expression, suppressed TBHP-mediated ER stress, and, in turn, prevented chondrocyte apoptosis and ECM degeneration. Furthermore, compared with the other two classic signaling pathways of ER stress, safranal can inhibit the PERK-eIF2α-CHOP axis at the lower concentration (5 and 15 μM). In vivo, using Safranin O staining, X-ray, immunofluorescence (IF), and immunohistochemical (IHC) staining, we demonstrated that OA progression can be postponed with intraperitoneal injection of 90 and 180 mg/kg safranal in an OA mouse model. Taken together, our analyses revealed that safranal can potentially prevent OA development.

Specific bFGF targeting of KIM-1 in ischemic kidneys protects against renal ischemia reperfusion injury in rats

Renal ischemia-reperfusion (I/R) injury is one of the major causes of acute kidney injury. However, there is still no effective treatment for this disease. Basic fibroblast growth factor (bFGF) has been reported to be beneficial for recovery from ischemic diseases. It is vital to increase the local concentration and reduce the diffusion of bFGF in vivo for renal I/R injury therapy. A targeted growth factor delivery system that responds to specific biological signals in the regenerative environment to guide release has been highlighted in tissue repair. In the present study, a specific peptide was fused with bFGF and called bFGF-kidney injury targeting (KIT-bFGF), and this compound specifically targeted kidney injury molecule-1 both in hypoxic renal HK-2 cells in vitro and ischemic kidneys in vivo after intravenous injection. When administered to rat models of renal I/R injury, KIT-bFGF attenuated renal tubule damage and fibrosis, and promoted functional recovery compared to the effects of native bFGF and the control. We also investigated the mechanism by which KIT-bFGF activated the ERK1/2 and Akt signaling pathways to significantly reduce apoptosis and protect against ischemic injury in the kidney. These results demonstrated that targeted delivery of KIT-bFGF could be an effective strategy for the treatment of renal I/R injury.

Pin1 aggravates renal injury induced by ischemia and reperfusion in rats via Nrf2/HO-1 mediated endoplasmic reticulum stress

PURPOSE

To investigate the role of peptidyl-prolyl cis/trans isomerase 1 (Pin1) on renal ischemia-reperfusion (I/R) injury and underlying mechanism.

METHODS

By establishing the in vitro and in vivo models of renal I/R, the role of Pin1 was explored by using molecular assays.

RESULTS

In renal I/R, endogenous Pin1 level was up-regulated in I/R-impaired kidney. Suppression of Pin1 with juglone afforded protection against I/R-mediated kidney dysfunction, and reduced I/R-induced endoplasmic reticulum (ER) stress in vivo. Consistent with the in vivo results, repression of Pin1 with juglone or gene knockdown with si-Pin1 conferred cytoprotection and restricted hypoxia/reoxygenation (H/R)-driven ER stress in HK-2 cells. Simultaneously, further study uncovered that Nrf-2/HO-1 signals was the association between Pin1 and ER stress in response to renal I/R. In addition, Nrf-2/HO-1 signal pathway was inactivated after kidney exposed to I/R, as indicated by the down-regulation of Nrf-2/HO-1 levels. Furthermore, inhibition of Pin1 remarkably rescued the inactivation ofNrf-2/HO-1.

CONCLUSIONS

Pin1 modulated I/R-mediated kidney injury in ER stress manner dependent on Nrf2-HO-1 pathway in I/R injury.

Application of Mesenchymal Stem Cells During Machine Perfusion: An Emerging Novel Strategy for Organ Preservation

Although solid organ transplantation remains the definitive management for patients with end-stage organ failure, this ultimate treatment has been limited by the number of acceptable donor organs. Therefore, efforts have been made to expand the donor pool by utilizing marginal organs from donation after circulatory death or extended criteria donors. However, marginal organs are susceptible to ischemia-reperfusion injury (IRI) and entail higher requirements for organ preservation. Recently, machine perfusion has emerged as a novel preservation strategy for marginal grafts. This technique continually perfuses the organs to mimic the physiologic condition, allows the evaluation of pretransplant graft function, and more excitingly facilitates organ reconditioning during perfusion with pharmacological, gene, and stem cell therapy. As mesenchymal stem cells (MSCs) have anti-oxidative, immunomodulatory, and regenerative properties, mounting studies have demonstrated the therapeutic effects of MSCs on organ IRI and solid organ transplantation. Therefore, MSCs are promising candidates for organ reconditioning during machine perfusion. This review provides an overview of the application of MSCs combined with machine perfusion for lung, kidney, liver, and heart preservation and reconditioning. Promising preclinical results highlight the potential clinical translation of this innovative strategy to improve the quality of marginal grafts.

Ameliorative role of alpha-lipoic acid in renal cortical structural damage, induced by limb ischemia-reperfusion injury in the rat

Ischemia-reperfusion injury is related to kidney dysfunction due to bilateral lower limb ischemia. This kidney injury may lead to acute kidney failure and mortality. Alpha-Lipoic Acid, a known antioxidant, can ameliorate kidney dysfunction and histopathology related to several etiologies. Ischemia was performed in adult male rats by bilateral femoral artery occlusion, then ischemia-reperfusion was done for 1 day and 7 days. Lipoic acid was administered to rats that had undergone ischemia-reperfusion for 7 days. The renal cortices of the kidneys of the tested groups were processed for light and electron microscopic examination. Immunohistochemical evaluation was performed using the following markers: cleaved caspase 3, inducible nitric oxide synthase, and tumor necrosis factor-alpha. There was damage to the renal cortical tubules and degeneration of podocytes and thickening of the glomerular basement membrane. Additionally, there was an increase in apoptosis and the inflammatory markers' immunoreactivity. Administration of alpha-lipoic acid resulted in improvement of the structural and immunohistochemical changes of the renal cortex. This may suggest a therapeutic rule of it and promising application for variable kidney injuries.

Effect of interferon regulatory factor 2 on inflammatory response and oxidative stress in lipopolysaccharide-induced acute kidney injury

Interferon regulatory factor (IRF) 2 plays an important role in lipopolysaccharide (LPS)-induced acute kidney injury (AKI). In this study, we explored the effects of IRF2 on apoptosis, inflammation, and oxidative stress in AKI C57BL/6 male mouse model and HEK293 cells following LPS treatment. To determine the effect of IRF2, short hairpin RNAs in mice and small interfering RNAs in cells were used to knockdown IRF2 expression. IRF2 expression, apoptosis, and severity of inflammatory and oxidative stress in mice and cells were measured. IRF2 levels were upregulated in LPS-treated mice and cells. IRF2 knockdown suppressed the levels of creatinine, blood urea nitrogen, and kidney injury molecule 1 and decreased the renal injury score in mice. Furthermore, IRF2 knockdown inhibited apoptosis and decreased the levels of inflammatory, reactive oxygen species (ROS), and malondialdehyde (MDA), but increased superoxide dismutase (SOD) levels in mice and cells. Furthermore, we found that the Janus kinase (JAK)/ signal transducer and activator of transcription pathway activated by LPS was inhibited by knockdown of IRF2, and enhanced by IRF2 overexpression. IRF2 overexpression increased cell apoptosis, inflammation, and ROS and MDA levels, and decreased SOD levels. However, the effect of IRF2 overexpression was reversed by the JAK inhibitor tofacitinib. Knockdown of IRF2 reduced LPS-induced renal tissue injury in vivo and in vitro through anti-inflammatory and antioxidant stress effects.

Akt Inhibition as Preconditioning Treatment to Protect Kidney Cells against Anoxia

Lesions issued from the ischemia/reperfusion (I/R) stress are a major challenge in human pathophysiology. Of human organs, the kidney is highly sensitive to I/R because of its high oxygen demand and poor regenerative capacity. Previous studies have shown that targeting the hypusination pathway of eIF5A through GC7 greatly improves ischemic tolerance and can be applied successfully to kidney transplants. The protection process correlates with a metabolic shift from oxidative phosphorylation to glycolysis. Because the protein kinase B Akt is involved in ischemic protective mechanisms and glucose metabolism, we looked for a link between the effects of GC7 and Akt in proximal kidney cells exposed to anoxia or the mitotoxic myxothiazol. We found that GC7 treatment resulted in impaired Akt phosphorylation at the Ser473 and Thr308 sites, so the effects of direct Akt inhibition as a preconditioning protocol on ischemic tolerance were investigated. We evidenced that Akt inhibitors provide huge protection for kidney cells against ischemia and myxothiazol. The pro-survival effect of Akt inhibitors, which is reversible, implied a decrease in mitochondrial ROS production but was not related to metabolic changes or an antioxidant defense increase. Therefore, the inhibition of Akt can be considered as a preconditioning treatment against ischemia.

Senkyunolide I alleviates renal Ischemia-Reperfusion injury by inhibiting oxidative stress, endoplasmic reticulum stress and apoptosis

BACKGROUND

Ligusticum striatum DC. is traditionally used to treat ischemic diseases because of its potent effect against blood stasis and thrombosis, including various cardiovascular, cerebral and renal diseases. Senkyunolide I (SEI), which is the major active phthalide ingredient of Ligusticum striatum DC., is mainly distributed in kidney and has been shown to attenuate ischemia reperfusion injury in liver. However, the underlying effect of SEI against renal ischemia-reperfusion injury (IRI) remain unclear.

METHODS

Renal ischemia reperfusion mice model was established by clamping bilateral renal pedicles. In vitro oxidative stress model was induced by H₂O₂. Level of blood urea nitrogen (BUN) and serum creatinine (SCr) was tested for in vivo model evaluation, while cell viability was tested using CCK8 to evaluate in vitro model. SEI solution containing 1% DMSO was injected intraperitoneally in the I/R group, while normal saline containing 1% DMSO injected in the Sham group. Reduced glutathione (GSH) solution containing 1% DMSO was used as a positive control.

RESULTS

SEI protected renal function and structural integrity. It reversed the I/R-induced elevation of BUN, SCr levels and renal pathological injury. The secretion of proinflammatory cytokines including TNF-α and IL-6 was inhibited, and the renal apoptosis was attenuated by SEI. In addition, SEI played a protective role by reducing the production of reactive oxidative species (ROS), as shown by the elevated expression of antioxidant proteins including Nrf2, HO-1, NQO1, and reduced expression of endoplasmic reticulum stress (ERS) related proteins including GRP78 and CHOP. It also attenuated HK2 cell injury in an in vitro model induced by H₂O₂.

CONCLUSIONS

SEI alleviates renal injury induced by ischemia reperfusion with anti-inflammatory, anti-endoplasmic reticulum stress, anti-oxidative and anti-apoptotic effect.

ER Stress in Cardiometabolic Diseases: From Molecular Mechanisms to Therapeutics

The endoplasmic reticulum (ER) hosts linear polypeptides and fosters natural folding of proteins through ER-residing chaperones and enzymes. Failure of the ER to align and compose proper protein architecture leads to accumulation of misfolded/unfolded proteins in the ER lumen, which disturbs ER homeostasis to provoke ER stress. Presence of ER stress initiates the cytoprotective unfolded protein response (UPR) to restore ER homeostasis or instigates a rather maladaptive UPR to promote cell death. Although a wide array of cellular processes such as persistent autophagy, dysregulated mitophagy, and secretion of proinflammatory cytokines may contribute to the onset and progression of cardiometabolic diseases, it is well perceived that ER stress also evokes the onset and development of cardiometabolic diseases, particularly cardiovascular diseases (CVDs), diabetes mellitus, obesity, and chronic kidney disease (CKD). Meanwhile, these pathological conditions further aggravate ER stress, creating a rather vicious cycle. Here in this review, we aimed at summarizing and updating the available information on ER stress in CVDs, diabetes mellitus, obesity, and CKD, hoping to offer novel insights for the management of these cardiometabolic comorbidities through regulation of ER stress.

Plicosepalus acacia Extract and Its Major Constituents, Methyl Gallate and Quercetin, Potentiate Therapeutic Angiogenesis in Diabetic Hind Limb Ischemia: HPTLC Quantification and LC-MS/MS Metabolic Profiling

Plicosepalus acacia (Fam. Loranthaceae) has been reported to possess hypoglycemic, antioxidant, antimicrobial, and anti-inflammatory effects. Liquid chromatography combined with tandem mass spectrometry (LC-MS/MS) analysis revealed the presence of a high content of polyphenolic compounds that are attributed to the therapeutic effects of the crude extract. In addition, methyl gallate and quercetin were detected as major phytomedicinal agents at concentrations of 1.7% and 0.062 g%, respectively, using high-performance thin layer chromatography (HPTLC). The present study investigated the effect of the P. acacia extract and its isolated compounds, methyl gallate and quercetin, on hind limb ischemia induced in type 1 diabetic rats. Histopathological examination revealed that treatment with P. acacia extract, methyl gallate, and quercetin decreased degenerative changes and inflammation in the ischemic muscle. Further biochemical assessment of the hind limb tissue showed decreased oxidative stress, increased levels of nitric oxide and endothelial nitric oxide synthase (eNOS), and enhancement of the levels of heme oxygenase-1 (HO-1) and vascular endothelial growth factor (VEGF) in the groups treated with methyl gallate and quercetin. Expression levels of hypoxia inducible factor-1 alpha (HIF-1α), VEGF, fibroblast growth factor-2 (FGF-2), and miR-146a were upregulated in the muscle tissue of methyl gallate- and quercetin-treated groups along with downregulation of nuclear factor kappa B (NF-κB). In conclusion, P. acacia extract and its isolated compounds, methyl gallate and quercetin, mediated therapeutic angiogenesis in diabetic hind limb ischemia.

Adipose-Derived Stromal Cell-Sheets Sandwiched, Book-Shaped Acellular Dermal Matrix Capable of Sustained Release of Basic Fibroblast Growth Factor Promote Diabetic Wound Healing

The management of diabetic wounds is a therapeutic challenge in clinical settings. Current tissue engineering strategies for diabetic wound healing are insufficient, owing to the lack of an appropriate scaffold that can load a large number of stem cells and induce the interaction of stem cells to form granulation tissue. Herein we fabricated a book-shaped decellularized dermal matrix (BDDM), which shows a high resemblance to native dermal tissue in terms of its histology, microstructure, and ingredients, is non-cytotoxic and low-immunogenic, and allows adipose-derived stromal cell (ASC) attachment and proliferation. Then, a collagen-binding domain (CBD) capable of binding collagen was fused into basic fibroblast growth factor (bFGF) to synthetize a recombinant growth factor (termed as CBD-bFGF). After that, CBD-bFGF was tethered onto the collagen fibers of BDDM to improve its endothelial inducibility. Finally, a functional scaffold (CBD-bFGF/BDDM) was fabricated. In vitro and in vivo experiments demonstrated that CBD-bFGF/BDDM can release tethered bFGF with a sustained release profile, steadily inducing the interaction of stem cells down to endothelial differentiation. ASCs were cultured to form a cell sheet and then sandwiched by CBD-bFGF/BDDM, thus enlarging the number of stem cells loaded into the scaffold. Using a rat model, the ASC sheets sandwiched with CBD-bFGF/BDDM (ASCs/CBD-bFGF/BDDM) were capable of enhancing the formation of granulation tissue, promoting angiogenesis, and facilitating collagen deposition and remodeling. Therefore, the findings of this study demonstrate that ASCs/CBD-bFGF/BDDM could be applicable for diabetic wound healing.

Modulatory Effect of Myokines on Reactive Oxygen Species in Ischemia/Reperfusion

There is a growing body of evidence showing the importance of physical activity against acute ischemic events in various organs. Ischemia/reperfusion injury (I/R) is characterized by tissue damage as a result of restriction and subsequent restoration of blood supply to an organ. Oxidative stress due to increased reactive oxygen species formation and/or insufficient antioxidant defense is considered to play an important role in I/R. Physical activity not only decreases the general risk factors for ischemia but also confers direct anti-ischemic protection via myokine production. Myokines are skeletal muscle-derived cytokines, representing multifunctional communication channels between the contracting skeletal muscle and other organs through an endocrine manner. In this review, we discuss the most prominent members of the myokines (i.e., brain-derived neurotrophic factor (BDNF), cathepsin B, decorin, fibroblast growth factors-2 and -21, follistatin, follistatin-like, insulin-like growth factor-1; interleukin-6, interleukin-7, interleukin-15, irisin, leukemia inhibitory factor, meteorin-like, myonectin, musclin, myostatin, and osteoglycin) with a particular interest in their potential influence on reactive oxygen and nitrogen species formation or antioxidant capacity. A better understanding of the mechanism of action of myokines and particularly their participation in the regulation of oxidative stress may widen their possible therapeutic use and, thereby, may support the fight against I/R.

Topical Application of Fibroblast Growth Factor 10-PLGA Microsphere Accelerates Wound Healing via Inhibition of ER Stress

There is a high incidence of acute and chronic skin defects caused by various reasons in clinically practice. The repair and functional reconstruction of skin defects have become a major clinical problem, which needs to be solved urgently. Previous studies have shown that fibroblast growth factor 10 (FGF10) plays a functional role in promoting the proliferation, migration, and differentiation of epithelial cells. However, little is known about the effect of FGF10 on the recovery process after skin damage. In this study, we found that the expression of endogenous FGF10 was increased during wound healing. We prepared FGF10-loaded poly(lactic-co-glycolic acid) (FGF10-PLGA) microspheres, and it could sustain release of FGF10 both in vitro and in vivo, accelerating wound healing. Further analysis revealed that compared with FGF10 alone, FGF10-PLGA microspheres significantly improved granulation formation, collagen synthesis, cell proliferation, and blood vessel density. In the meantime, we found that FGF10-PLGA microspheres inhibited the expression of endoplasmic reticulum (ER) stress markers. Notably, activating ER stress with tunicamycin (TM) reduced therapeutic effects of FGF10-PLGA microspheres in wound healing, whereas inhibition of ER stress with 4-phenyl butyric acid (4-PBA) improved the function of FGF10-PLGA microspheres. Taken together, this study indicates that FGF10-PLGA microspheres accelerate wound healing presumably through modulating ER stress.

Fibroblast growth factor 2 conjugated superparamagnetic iron oxide nanoparticles (FGF2-SPIONs) ameliorate hepatic stellate cells activation in vitro and acute liver injury in vivo

Liver diseases are the growing health problem with no clinically approved therapy available. Activated hepatic stellate cells (HSCs) are the key driver cells responsible for extracellular matrix deposition, the hallmark of liver fibrosis. Fibroblast growth factor 2 (FGF2) has shown to possess anti-fibrotic effects in fibrotic diseases including liver fibosis, and promote tissue regeneration. Among the fibroblast growth factor receptors (FGFRs), FGF2 interact primarily with FGFR1, highly overexpressed on activated HSCs, and inhibit HSCs activation. However, FGF2 poses several limitations including poor systemic half-life and stability owing to enzymatic degradation. The aim of this study is to improve the stability and half-life of FGF2 thereby improving the therapuetic efficacy of FGF2 for the treatment of liver fibrosis. We found that FGFR1-3 mRNA levels were overexpressed in cirrhotic human livers, while FGFR1c, 2c, 3c, 4 and FGF2 mRNA levels were overexpressed in TGFβ-activated HSCs (LX2 cells) and FGFR1 protein expression was highly increased in TGFβ-activated HSCs. Treatment with FGF2 inhibited TGFβ-induced HSCs activation, migration and contraction in vitro. FGF2 was conjugated to superparamagnetic iron-oxide nanoparticles (SPIONs) using carbodiimide chemistry, and the resulting FGF2-SPIONs were confirmed by dynamic light scattering (DLS), zeta potential, dot-blot analysis and Prussian Blue iron-staining. In vitro, treatment with FGF2-SPIONs evidenced increased therapeutic effects (attenuated TGFβ-induced HSCs activation, migration and contraction) of FGF2 in TGFβ-activated HSCs and ameliorated early liver fibrogenesis in vivo in acute carbon tetrachloride (CCl₄)-induced liver injury mouse model. In contrast, free FGF2 showed no significant effects in vivo. Altogether, this study presents a promising therapeutic approach using FGF2-SPIONs for the treatment of liver fibrosis.