Renoprotective effect of long acting thioredoxin by modulating oxidative stress and macrophage migration inhibitory factor against rhabdomyolysis-associated acute kidney injury

Renoprotective effect of thymoquinone against rhabdomyolysis-induced acute kidney injury in the rat model

Objectives

Rhabdomyolysis leads to the release of myoglobin, sarcoplasmic proteins, and electrolytes into the blood circulation causing acute kidney injury (AKI). Thymoquinone, a natural compound found in Nigella sativa seeds, has antioxidant and anti-inflammatory effects. This investigation assessed the renoprotective effect of thymoquinone on rhabdomyolysis-induced AKI in rats.

Materials and Methods

Male Wistar rats were categorized into six groups (n = 6): 1. Control: (normal saline), 2. Glycerol (50 ml/kg, single dose, IM), 3-5: Glycerol + thymoquinone (1, 2.5 and 5 mg/kg, 4 days, IP), 6. Thymoquinone (5 mg/kg). On day 5, serum and kidney tissue were isolated and the amounts of serum creatinine and blood urea nitrogen (BUN), renal malondialdehyde (MDA), glutathione (GSH.), tumor necrosis factor-alpha (TNF-α), neutrophil gelatinase-associated lipocalin (NGAL), and pathological changes were evaluated.

Results

Glycerol increased creatinine, BUN, MDA, TNF-α, and NGAL levels. It decreased GSH amounts and caused renal tubular necrosis, glomerular atrophy, and myoglobin cast in kidney tissue. Co-administration of glycerol and thymoquinone reduced creatinine, BUN, histopathological alterations, and MDA levels, and enhanced GSH amounts. Administration of glycerol and thymoquinone (5 mg/kg) had no significant effect on TNF-α amount but decreased NGAL protein levels. The administration of thymoquinone (5 mg/kg) alone did not display a significant difference from the control group.

Conclusion

Rhabdomyolysis from glycerol injection in rats can cause kidney damage. Thymoquinone may attenuate renal dysfunction and oxidative stress. However, the TNF-α level was not significantly affected. Further studies are needed to explore the potential therapeutic effects of thymoquinone in managing AKI.

Effectiveness of Albumin-Fused Thioredoxin against 6-Hydroxydopamine-Induced Neurotoxicity In Vitro

Parkinson's disease (PD) is a neurodegenerative disorder caused by oxidative stress-dependent loss of dopaminergic neurons in the substantia nigra and elevated microglial inflammatory responses. Recent studies show that cell loss also occurs in the hypothalamus in PD. However, effective treatments for the disorder are lacking. Thioredoxin is the major protein disulfide reductase in vivo. We previously synthesized an albumin-thioredoxin fusion protein (Alb-Trx), which has a longer plasma half-life than thioredoxin, and reported its effectiveness in the treatment of respiratory and renal diseases. Moreover, we reported that the fusion protein inhibits trace metal-dependent cell death in cerebrovascular dementia. Here, we investigated the effectiveness of Alb-Trx against 6-hydroxydopamine (6-OHDA)-induced neurotoxicity in vitro. Alb-Trx significantly inhibited 6-OHDA-induced neuronal cell death and the integrated stress response. Alb-Trx also markedly inhibited 6-OHDA-induced reactive oxygen species (ROS) production, at a concentration similar to that inhibiting cell death. Exposure to 6-OHDA perturbed the mitogen-activated protein kinase pathway, with increased phosphorylated Jun N-terminal kinase and decreased phosphorylated extracellular signal-regulated kinase levels. Alb-Trx pretreatment ameliorated these changes. Furthermore, Alb-Trx suppressed 6-OHDA-induced neuroinflammatory responses by inhibiting NF-κB activation. These findings suggest that Alb-Trx reduces neuronal cell death and neuroinflammatory responses by ameliorating ROS-mediated disruptions in intracellular signaling pathways. Thus, Alb-Trx may have potential as a novel therapeutic agent for PD.

Heme Proteins and Kidney Injury: Beyond Rhabdomyolysis

Heme proteins, the stuff of life, represent an ingenious biologic strategy that capitalizes on the biochemical versatility of heme, and yet is one that avoids the inherent risks to cellular vitality posed by unfettered and promiscuously reactive heme. Heme proteins, however, may be a double-edged sword because they can damage the kidney in certain settings. Although such injury is often viewed mainly within the context of rhabdomyolysis and the nephrotoxicity of myoglobin, an increasing literature now attests to the fact that involvement of heme proteins in renal injury ranges well beyond the confines of this single disease (and its analog, hemolysis); indeed, through the release of the defining heme motif, destabilization of intracellular heme proteins may be a common pathway for acute kidney injury, in general, and irrespective of the underlying insult. This brief review outlines current understanding regarding processes underlying such heme protein-induced acute kidney injury (AKI) and chronic kidney disease (CKD). Topics covered include, among others, the basis for renal injury after the exposure of the kidney to and its incorporation of myoglobin and hemoglobin; auto-oxidation of myoglobin and hemoglobin; destabilization of heme proteins and the release of heme; heme/iron/oxidant pathways of renal injury; generation of reactive oxygen species and reactive nitrogen species by NOX, iNOS, and myeloperoxidase; and the role of circulating cell-free hemoglobin in AKI and CKD. Also covered are the characteristics of the kidney that render this organ uniquely vulnerable to injury after myolysis and hemolysis, and pathobiologic effects emanating from free, labile heme. Mechanisms that defend against the toxicity of heme proteins are discussed, and the review concludes by outlining the therapeutic strategies that have arisen from current understanding of mechanisms of renal injury caused by heme proteins and how such mechanisms may be interrupted.

Macrophage migration inhibitory factor in acute kidneyinjury

Acute kidney injury (AKI) is a complex clinical syndrome with multiple etiologies and pathogenesis, which lacks early biomarkers and targeted therapy. Recently, macrophage migration inhibitory factor (MIF) family protein have received increasing attention owing to its pleiotropic protein molecule character in acute kidney injury, where it performed a dual role in the pathological process. macrophage migration inhibitory factor and macrophage migration inhibitory factor-2 are released into the peripheral circulation when Acute kidney injury occurs and interact with various cellular pathways. On the one hand, macrophage migration inhibitory factor exerts a protective effect in anti-oxidation and macrophage migration inhibitory factor-2 promotes cell proliferation and ameliorates renal fibrosis. On the other hand, macrophage migration inhibitory factor aggravates renal injury as an upstream inflammation factor. Herein, we provide an overview on the biological role and possible mechanisms of macrophage migration inhibitory factor and macrophage migration inhibitory factor-2 in the process of Acute kidney injury and the clinical application prospects of macrophage migration inhibitory factor family proteins as a potential therapeutic target.

Engineering of a Long-Acting Bone Morphogenetic Protein-7 by Fusion with Albumin for the Treatment of Renal Injury

The bone morphogenetic protein-7 (BMP7) is capable of inhibiting TGF-β/Smad3 signaling, which subsequently results in protecting the kidney from renal fibrosis, but its lower blood retention and osteogenic activity are bottlenecks for its clinical application. We report herein on the fusion of carbohydrate-deficient human BMP7 and human serum albumin (HSA-BMP7) using albumin fusion technology and site-directed mutagenesis. When using mouse myoblast cells, no osteogenesis was observed in the glycosylated BMP7 derived from Chinese hamster ovary cells in the case of unglycosylated BMP7 derived from Escherichia coli and HSA-BMP7. On the contrary, the specific activity for the Smad1/5/8 phosphorylation of HSA-BMP7 was about 25~50-times lower than that for the glycosylated BMP7, but the phosphorylation activity of the HSA-BMP7 was retained. A pharmacokinetic profile showed that the plasma half-life of HSA-BMP7 was similar to that for HSA and was nearly 10 times longer than that of BMP7. In unilateral ureteral obstruction mice, weekly dosing of HSA-BMP7 significantly attenuated renal fibrosis, but the individual components, i.e., HSA or BMP7, did not. HSA-BMP7 also attenuated a cisplatin-induced acute kidney dysfunction model. The findings reported herein indicate that HSA-BMP7 has the potential for use in clinical applications for the treatment of renal injuries.

Angiotensin 1-7 mitigates rhabdomyolysis induced renal injury in rats via modulation of TLR-4/NF-kB/iNOS and Nrf-2/heme‑oxygenase-1 signaling pathways

AIMS

Rhabdomyolysis (RM) is a critical condition with a high mortality rate, but effective management is still deficient. Till date, there are no studies that have addressed the effect of angiotensin 1-7 in this condition, hence, the rationale of this study was to evaluate the potential protective effect of Angiotensin 1-7 (Ang1-7), on rhabdomyolysis (RM) induced kidney injury in rats and detecting the underlying mechanistic insights.

MAIN METHODS

Forty adult male albino rats were divided into groups; the control group, RM group, RM+Ang1-7 group, and RM+Ang1-7+ A779 group. Sera and urine samples were collected for analysis of renal and muscle injury markers. Kidney tissues were taken for estimation of oxidative, inflammatory, and apoptotic markers as well as angiotensin-II (Ang II) and Ang1-7. Renal histology and expression of inducible nitric oxide synthase-1 (iNOS), real-time PCR for angiotensin-converting enzyme-2 (ACE-2), nuclear erythroid factor-2 (Nrf-2), Toll like receptor 4 (TLR-4) and NF-kB in kidney tissues were also measured.

KEY FINDINGS

Induction of RM caused renal oxidative stress injury, inflammation, apoptosis and marked deterioration in kidney functions as well as reduction of Ang1-7 and raised Angiotensin-II level in kidney tissues. Administration of Ang1-7 to the RM group reversed all the affected parameters which were blocked by A779 administration (Mas receptor blocker).

SIGNIFICANCE

We concluded that Ang1-7 could be a potential therapeutic agent that could mitigate RM-induced renal injury. The underlying mechanisms may involve Stimulation of the ACE-2/Ang1-7/MasR axis and modulation of TLR-4/NF-kB/iNOS and Nrf-2/heme‑oxygenase -1 pathways.

Urinary Thioredoxin as a Biomarker of Renal Redox Dysregulation and a Companion Diagnostic to Identify Responders to Redox-Modulating Therapeutics

Significance: The development and progression of renal diseases, including acute kidney injury (AKI) and chronic kidney disease (CKD), are the result of heterogeneous pathophysiology that reflects a range of environmental factors and, in a lesser extent, genetic mutations. The pathophysiology specific to most kidney diseases is not currently identified; therefore, these diseases are diagnosed based on non-pathological factors. For that reason, pathophysiology-based companion diagnostics for selection of pathophysiology-targeted treatments have not been available, which impedes personalized medicine in kidney disease. Recent Advances: Pathophysiology-targeted therapeutic agents are now being developed for the treatment of redox dysregulation. Redox modulation therapeutics, including bardoxolone methyl, suppresses the onset and progression of AKI and CKD. On the other hand, pathophysiology-targeted diagnostics for renal redox dysregulation are also being developed. Urinary thioredoxin (TXN) is a biomarker that can be used to diagnose tubular redox dysregulation. AKI causes oxidation and urinary excretion of TXN, which depletes TXN from the tubules, resulting in tubular redox dysregulation. Urinary TXN is selectively elevated at the onset of AKI and correlates with the progression of CKD in diabetic nephropathy. Critical Issues: Diagnostic methods should provide information about molecular mechanisms that aid in the selection of appropriate therapies to improve the prognosis of kidney disease. Future Directions: A specific diagnostic method enabling detection of redox dysregulation based on pathological molecular mechanisms is much needed and could provide the first step toward personalized medicine in kidney disease. Urinary TXN is a candidate for a companion diagnostic method to identify responders to redox-modulating therapeutics. Antioxid. Redox Signal. 36, 1051-1065.

Systemic Review of Animal Models Used in the Study of Crush Syndrome

ABSTRACT

Crush syndrome (CS), also known as traumatic rhabdomyolysis, is the leading cause of death following extrication from structural collapse due to earthquakes. Due to the unfeasibility of human studies, animal models are used to study crush syndrome pathophysiology, including biochemistry and treatment regimes. The aim of this systematic literature review was to identify the differences and benefits of various animal models used in the study of CS and provide valuable information for design of future research. A systematic search was conducted in two methods: with the filters "(crush syndrome) AND (crush muscle injury)" and with the keywords "(crush syndrome) AND (animal model)" covering all articles in the PubMed databases. The search generated 378 articles. After screening abstracts, 91 articles were retrieved and read, then 11 repeated articles were removed and 2 reference papers were included. We finally reviewed 82 original articles. There appear to be two primary methods employed for inducing crush syndrome in animal models, which are chemically induced injury and physically induced injury. Chemical method mainly includes intramuscular (IM) injection of tissue extract solution and IM injection of 50% glycerine. Physical method can be classified into invasive and non-invasive physical compression by elasticated material, inflatable band and heavy load. Various species of animals have been used to study CS, including mice (13.4%), rats (68.3%), rabbits (11.0%), canines (4.9%), goats (1.2%), and pigs (1.2%). Small animals are suitable for researches exploring the mechanism of disease or drug efficacy while large animals can work better with clinical application-related researches. In regard to the choice of modeling method, compressing the certain muscle of animals by heavy things is superior to others to cause systemic trauma-related rhabdomyolysis signs. In addition, due to the significant burden of crush injuries on animals, further attention shall be paid to the selection of the most suitable anesthetics and appropriate analgesics.

Protective effect of tin chloride on rhabdomyolysis-induced acute kidney injury in rats

The heme component of myoglobin plays a crucial role in the pathogenesis of rhabdomyolysis-associated acute kidney injury (RM-AKI). Heme oxiganenase-1 (HO-1) is the rate-limiting enzyme of heme catabolism, and its metabolites, iron, biliverdin, and carbon monoxide, have antioxidant properties. Tin chloride (SnCl₂) is a kidney specific HO-1 inducer. In this study, we examined whether the induction of HO-1 in the kidney by SnCl_₂ pretreatment ameliorates RM-AKI in rats and if the effect is due to the degradation of excess renal free heme. We developed an RM-AKI rat (male Sprague-Dawley rats) model by injecting glycerol (Gly) in the hind limbs. RM-AKI rats were pretreated with saline or SnCl_₂ or additional SnMP (tin mesoporphyrin, a specific HO inhibitor) followed by Gly treatment. Serum blood urea nitrogen (BUN) and creatinine (Crea) were measured as indicators of renal function. Renal free heme level was assessed based on the levels of δ-aminolevulinate synthase (ALAS1), a heme biosynthetic enzyme, and nuclear BTB and CNC homology 1 (Bach1), an inhibitory transcription factor of HO-1. Elevated free heme levels lead to decreases in ALAS1 and nuclear Bach1. After 24 h of Gly injection, serum BUN and Crea levels in saline-pretreated rats were significantly higher than those in untreated control rats. In contrast, SnCl_₂-pretreated rats showed no significant increase in the indices. However, additional treatment of SnMP abolished the beneficial effect of SnCl_₂. Renal ALAS1 mRNA levels and renal nuclear Bach1 protein levels in the saline pretreated rats were significantly lower than those in control rats 3 h after Gly injection. In contrast, the levels in SnCl₂-pretreated rats were not altered. The findings indicate that SnCl₂ pretreatment confers protection against RM-AKI by virtue of HO-1 induction in the renal system, at least in part through excess free heme degradation.

Long-Acting Thioredoxin Ameliorates Doxorubicin-Induced Cardiomyopathy via Its Anti-Oxidative and Anti-Inflammatory Action

Although the number of patients with heart failure is increasing, a sufficient treatment agent has not been established. Oxidative stress and inflammation play important roles in the development of myocardial remodeling. When thioredoxin (Trx), an endogenous anti-oxidative and inflammatory modulator with a molecular weight of 12 kDa, is exogenously administered, it disappears rapidly from the blood circulation. In this study, we prepared a long-acting Trx, by fusing human Trx (HSA-Trx) with human serum albumin (HSA) and evaluated its efficacy in treating drug-induced heart failure. Drug-induced cardiomyopathy was created by intraperitoneally administering doxorubicin (Dox) to mice three times per week. A decrease in heart weight, increased myocardial fibrosis and markers for myocardial damage that were observed in the Dox group were suppressed by HSA-Trx administration. HSA-Trx also suppressed the expression of atrogin-1 and myostatin, myocardial atrophy factors in addition to suppressing oxidative stress and inflammation. In the Dox group, a decreased expression of endogenous Trx in cardiac tissue and an increased expression of macrophage migration inhibitory factor were observed, but these changes were restored to normal levels by HSA-Trx administration. These findings suggest that HSA-Trx improves the pathological condition associated with Dox-induced cardiomyopathy by its anti-oxidative/anti-inflammatory and myocardial atrophy inhibitory action.

Recombinant Long-Acting Thioredoxin Ameliorates AKI to CKD Transition via Modulating Renal Oxidative Stress and Inflammation

An effective strategy is highly desirable for preventing acute kidney injury (AKI) to chronic kidney disease (CKD) transition. Thioredoxin-1 (Trx), a redox-active protein that has anti-oxidative and anti-inflammatory properties, would be a candidate for this but its short half-life limits its clinical application. In this study, we examined the renoprotective effect of long-acting Trx that is comprised of human albumin and Trx (HSA-Trx) against AKI to CKD transition. AKI to CKD mice were created by renal ischemia-reperfusion (IR). From day 1 to day 14 after renal IR, the recovery of renal function was accelerated by HSA-Trx administration. On day 14, HSA-Trx reduced renal fibrosis compared with PBS treatment. At the early phase of fibrogenesis (day 7), HSA-Trx treatment suppressed renal oxidative stress, pro-inflammatory cytokine production and macrophage infiltration, thus ameliorating tubular injury and fibrosis. In addition, HSA-Trx treatment inhibited G2/M cell cycle arrest and apoptosis in renal tubular cells. While renal Trx protein levels were decreased after renal IR, the levels were recovered by HSA-Trx treatment. Together, HSA-Trx has potential for use in the treatment of AKI to CKD transition via its effects of modulating oxidative stress and inflammation.

Thalidomide reduces glycerol-induced acute kidney injury by inhibition of NF-κB, NLRP3 inflammasome, COX-2 and inflammatory cytokines

Acute kidney injury (AKI) is an important clinical complication of rhabdomyolysis. The inflammatory processes are involved in the pathogenesis of AKI induced by rhabdomyolysis. Thalidomide is an anti-inflammatory agent that has been used in the treatment of inflammatory disorders. The aim of this study was to investigate the therapeutic effect of thalidomide and its underlying mechanisms on a mouse model of rhabdomyolysis-induced AKI. Mice were injected with a single dose of glycerol (50%, 10 ml/kg, im) to induce AKI, and treated with thalidomide (40 and 80 mg/kg/day, orally) for 2 days. Renal tissue and blood samples were collected for histological and biochemical analysis. In thalidomide treated mice, blood urea nitrogen (BUN) (59.3 ± 19.6 vs. 223 ± 33 mg/dl), plasma creatinine (0.58 ± 0.3 vs. 1.28 ± 0.3 mg/dl), relative kidney weight (0.93 ± 0.13% vs. 1.22 ± 0.1%) and histopathological damage (1.5 ± 0.8 vs. 3.3 ± 1.1 score) were significantly lower as compared to the glycerol group. The results also showed that the levels of malondialdehyde (MDA) (0.13 ± 0.02 vs. 0.2 ± 0.01 µM/mg), myeloperoxidase (MPO) (0.1 ± 0.05 vs. 0.25 ± 0.02 U/mg) and the expression of nuclear factor kappa B (NF-κB) (1.7-fold), NLRP3 inflammasome (1.4-fold) and cyclooxygenase (COX)-2 (3-fold) in renal tissue were significantly lower in thalidomide treated group than those in the glycerol group. Thalidomide treatment resulted in lower renal pro-inflammatory cytokines tumor necrosis factor (TNF)-α (6.7 ± 0.8 vs. 12.3 ± 1.2 ng/ml), interleukin (IL)-1β (3.2 ± 0.5 vs. 5.1 ± 0.3 pg/mg), IL-6 (24.7 ± 2.4 vs. 33 ± 3 pg/mg) and transforming growth factor (TGF)-β1 (0.6 ± 0.17 vs. 1.56 ± 0.24 ng/ml) than those in the glycerol treated mice. In addition the levels of monocyte chemoattractant protein (MCP)-1 (9.5 ± 1 vs. 12.8 ± 1.1 pg/mg) and intercellular adhesion molecule (ICAM)-1 (22.8 ± 7.8 vs. 53.3 ± 5.5 pg/mg) were significantly lower in renal tissue of mice treated with thalidomide as compared to the glycerol treated mice. In conclusion these data revealed that thalidomide may be a potential therapeutic approach against rhabdomyolysis-induced AKI through inhibition of inflammatory responses.

Major signaling pathways and key mediators of macrophages in acute kidney injury (Review)

Acute kidney injury (AKI) has become a global public health problem with high morbidity and mortality rates, as well as high healthcare costs. Immune cells, particularly macrophages, which regulate tissue development, destroy pathogens, control homeostasis and repair wounds, play crucial and complex roles in AKI. In various types of AKI, numerous rapidly recruited monocytes and tissue-resident macrophages act in a coordinated manner. Thus, elucidating the phenotypic and functional characteristics of macrophages in AKI is essential for identifying potential therapeutic targets. Macrophage-sensing mediators and macrophage-derived mediators participate in the major macrophage-related signaling pathways in AKI, which regulate macrophage polarization and determine disease progression. In conclusion, macrophages change their roles and regulatory mechanisms during the occurrence and development of AKI. The aim of the present review was to contribute to an improved understanding of AKI and to the identification of novel therapeutic targets for this condition.

MBD2 mediates renal cell apoptosis via activation of Tox4 during rhabdomyolysis-induced acute kidney injury

Our study investigated the role of Methyl‐CpG–binding domain protein 2 (MBD2) in RM‐induced acute kidney injury (AKI) both in vitro and in vivo. MBD2 was induced by myoglobin in BUMPT cells and by glycerol in mice. MBD2 inhibition via MBD2 small interfering RNA and MBD2‐knockout (KO) attenuated RM‐induced AKI and renal cell apoptosis. The expression of TOX high mobility group box family member 4 (Tox4) induced by myoglobin was markedly reduced in MBD2‐KO mice. Chromatin immunoprecipitation analysis indicated that MBD2 directly bound to CpG islands in the Tox4 promoter region, thus preventing promoter methylation. Furthermore, siRNA inhibition of Tox4 attenuated myoglobin‐induced apoptosis in BUMPT cells. Finally, MBD2‐KO mice exhibited glycerol‐induced renal cell apoptosis by inactivation of Tox4. Altogether, our results suggested that MBD2 plays a role in RM‐induced AKI via the activation of Tox4 and represents a potential target for treatment of RM‐associated AKI.

Acute glucose fluctuation promotes RAGE expression via reactive oxygen species‑mediated NF‑κB activation in rat podocytes

Diabetic nephropathy (DN) is a common chronic complication of diabetes, for which acute glucose fluctuation (AGF) is a potential risk factor. Fluctuating hyperglycemia has been confirmed to induce more serious kidney damage than hyperglycemia in diabetic rats; however, the mechanism remains unknown. The purpose of this study was to explore the potential role of AGF in the progression of DN. Viability of rat podocytes following 72-h AGF treatment was detected using Cell Counting-Kit-8. The rates of apoptosis and the level of reactive oxygen species (ROS) in rat podocytes were assessed by flow cytometry. Western blotting and reverse transcription-quantitative PCR were performed to measure relative protein and mRNA expression levels, respectively. Transfection with an mRFP-GFP-LC3 adenoviral vector was used to track autophagic flux under confocal microscopy. The results indicated that AGF could inhibit cell proliferation, promote TNF-α, interleukin-1β (IL-1β), and reactive oxygen species (ROS) generation, and increase autophagy in rat podocytes. Moreover, AGF upregulated receptor for advanced glycation end products (RAGE) expression via activation of NF-κB/p65 and IκBα. Pretreatment with 5 mM N-Acetyl-L-cysteine or 10 µM pyrrolidine dithiocarbamate effectively reduced cellular damage and inhibited activation of the NF-κB/RAGE signaling pathway. Thus, AGF induces rat podocyte injury by aggravating oxidative stress, promoting the inflammatory response, and regulating ROS-mediated NF-κB/RAGE activation.

Thioredoxin-albumin fusion protein prevents urban aerosol-induced lung injury via suppressing oxidative stress-related neutrophil extracellular trap formation

The number of deaths from air pollution worldwide is estimated at 8.8 million per year, more than the number of deaths from smoking. Air pollutants, such as PM_2.5, are known to induce respiratory and cardiovascular diseases by inducing oxidative stress. Thioredoxin (Trx) is a 12-kDa endogenous protein that exerts antioxidant activity by promoting dithiol disulfide exchange reactions. We previously synthesized human serum albumin-fused thioredoxin (HSA-Trx), which has a longer half-life in plasma compared with Trx, and demonstrated its efficacy against various diseases including respiratory diseases. Here, we examined the effect of HSA-Trx on urban aerosol-induced lung injury in mice. Urban aerosols induced lung injury and inflammatory responses in ICR mice, but intravenous administration of HSA-Trx markedly inhibited these responses. We next analyzed reactive oxygen species (ROS) production in murine lungs using an in vivo imaging system. The results show that intratracheal administration of urban aerosols induced ROS production that was inhibited by intravenously administered HSA-Trx. Finally, we found that HSA-Trx inhibited the urban aerosol-induced increase in levels of neutrophilic extracellular trap (NET) indicators (i.e., double-stranded DNA, citrullinated histone H3, and neutrophil elastase) in bronchoalveolar lavage fluid (BALF). Together, these findings suggest that HSA-Trx prevents urban aerosol-induced acute lung injury by suppressing ROS production and neutrophilic inflammation. Thus, HSA-Trx may be a potential candidate drug for preventing the onset or exacerbation of lung injury caused by air pollutants.

Systemic and sustained thioredoxin analogue prevents acute kidney injury and its-associated distant organ damage in renal ischemia reperfusion injury mice

The mortality of patients with acute kidney injury (AKI) remains high due to AKI associated-lung injury. An effective strategy for preventing both AKI and AKI-associated lung injury is urgently needed. Thioredoxin-1 (Trx) is a redox-active protein that possesses anti-oxidative, anti-apoptotic and anti-inflammatory properties including modulation of macrophage migration inhibitory factor (MIF), but its short half-life limits its clinical application. Therefore, we examined the preventive effect of a long-acting Trx, which is a fusion protein of albumin and Trx (HSA-Trx), against AKI and AKI-associated lung injury. Recombinant HSA-Trx was expressed using a Pichia expression system. AKI-induced lung injury mice were generated by bilateral renal ischemia reperfusion injury (IRI). HSA-Trx administration attenuated renal IRI and its-associated lung injury. Both renal and pulmonary oxidative stress were suppressed by HSA-Trx. Moreover, HSA-Trx inhibited elevations of plasma IL-6 and TNF-α level, and suppressed IL-6-CXCL1/2-mediated neutrophil infiltration into lung and TNF-α-mediated pulmonary apoptosis. Additionally, HSA-Trx suppressed renal IRI-induced MIF expression in kidney and lung. Administration of HSA-Trx resulted in a significant increase in the survival rate of renal IRI mice. Collectively, HSA-Trx could have therapeutic utility in preventing both AKI and AKI-associated lung injury as a consequence of its systemic and sustained multiple biological action.

Rhabdomyolysis-Induced AKI Was Ameliorated in NLRP3 KO Mice via Alleviation of Mitochondrial Lipid Peroxidation in Renal Tubular Cells

Introduction: A recent study showed that early renal tubular injury is ameliorated in Nod-like receptor pyrin domain-containing protein 3 (NLRP3) KO mice with rhabdomyolysis-induced acute kidney injury (RIAKI). However, the precise mechanism has not been determined. Therefore, we investigated the role of NLRP3 in renal tubular cells in RIAKI. Methods: Glycerol-mediated RIAKI was induced in NLRP3 KO and wild-type (WT) mice. The mice were euthanized 24 h after glycerol injection, and both kidneys and plasma were collected. HKC-8 cells were treated with ferrous myoglobin to mimic a rhabdomyolytic environment. Results: Glycerol injection led to increase serum creatinine, aspartate aminotransferase (AST), and renal kidney injury molecule-1 (KIM-1) level; renal tubular necrosis; and apoptosis. Renal injury was attenuated in NLRP3 KO mice, while muscle damage and renal neutrophil recruitment did not differ between NLRP3 KO mice and WT mice. Following glycerin injection, increases in cleaved caspase-3, poly (ADP-ribose) polymerase (PARP), and a decrease in the glutathione peroxidase 4 (GPX-4) level were observed in the kidneys of mice with RIAKI, and these changes were alleviated in the kidneys of NLRP3 KO mice. NLRP3 was upregulated, and cell viability was suppressed in HKC-8 cells treated with ferrous myoglobin. Myoglobin-induced apoptosis and lipid peroxidation were significantly decreased in siNLRP3-treated HKC-8 cells compared to ferrous myoglobin-treated HKC-8 cells. Myoglobin reduced the mitochondrial membrane potential and increased mitochondrial fission and reactive oxygen species (ROS) and lipid peroxidation levels, which were restored to normal levels in NLRP3-depleted HKC-8 cells. Conclusions: NLRP3 depletion ameliorated renal tubular injury in a murine glycerol-induced acute kidney injury (AKI) model. A lack of NLRP3 improved tubular cell viability via attenuation of myoglobin-induced mitochondrial injury and lipid peroxidation, which might be the critical factor in protecting the kidney.

Ramipril blunts glycerol-induced acute renal failure in rats through its antiapoptosis, anti-inflammatory, antioxidant, and renin-inhibiting properties

OBJECTIVES

Acute kidney injury (AKI) is a malady with a sudden onset resulting in buildup of waste matters in the body, but a specific cure hasn't been found as a lasting solution to AKI. In this study, ramipril was evaluated for its potential therapy in glycerol-induced AKI in rats.

METHODS

Twenty animals were divided into four groups of five animals each. Group I was the control while group II was given glycerol on day 8 only, groups III and IV were administered with pioglitazone (reference drug) and ramipril for seven days respectively and on day 8 received glycerol. On the ninth day, blood and tissue samples were taken to assay for serum indicators of oxidative damage, enzymatic and nonenzymatic antioxidants, and creatinine and blood urea nitrogen. Animals were sacrificed thereafter; kidney was harvested for histological and immunohistochemical analysis. Expressions of caspase 3, renin receptor, NK-KB, and KIM-1 were carried out.

RESULTS

Ramipril significantly inhibited indicators of oxidative damage while also significantly increasing levels of enzymatic and nonenzymatic antioxidant markers. These drugs also significantly lowered the levels of creatinine and blood urea nitrogen. Histology also indicated that while there were massive infiltration of leucocytes and congestion of the kidney in toxicant group, the ramipril-treated group showed a milder condition. In immunohistochemistry, the two drugs significantly inhibited the expressions of the four proteins, which were highly expressed in the toxicant group.

CONCLUSIONS

The study showed that ramipril and pioglitazone have nephroprotective effect and thus have the ability to blunt AKI through their anti-inflammatory, antiapoptosis, antirenin, and antioxidant properties.

Complement activation is a crucial driver of acute kidney injury in rhabdomyolysis

Rhabdomyolysis is a life-threatening condition caused by skeletal muscle damage with acute kidney injury being the main complication dramatically worsening the prognosis. Specific treatment for rhabdomyolysis-induced acute kidney injury is lacking and the mechanisms of the injury are unclear. To clarify this, we studied intra-kidney complement activation (C3d and C5b-9 deposits) in tubules and vessels of patients and mice with rhabdomyolysis-induced acute kidney injury. The lectin complement pathway was found to be activated in the kidney, likely via an abnormal pattern of Fut2-dependent cell fucosylation, recognized by the pattern recognition molecule collectin-11 and this proceeded in a C4-independent, bypass manner. Concomitantly, myoglobin-derived heme activated the alternative pathway. Complement deposition and acute kidney injury were attenuated by pre-treatment with the heme scavenger hemopexin. This indicates that complement was activated in a unique double-trigger mechanism, via the alternative and lectin pathways. The direct pathological role of complement was demonstrated by the preservation of kidney function in C3 knockout mice after the induction of rhabdomyolysis. The transcriptomic signature for rhabdomyolysis-induced acute kidney injury included a strong inflammatory and apoptotic component, which were C3/complement-dependent, as they were normalized in C3 knockout mice. The intra-kidney macrophage population expressed a complement-sensitive phenotype, overexpressing CD11b and C5aR1. Thus, our results demonstrate a direct pathological role of heme and complement in rhabdomyolysis-induced acute kidney injury. Hence, heme scavenging and complement inhibition represent promising therapeutic strategies.

Elevated serum magnesium lowers calcification propensity in Memo1-deficient mice

MEdiator of cell MOtility1 (MEMO1) is a ubiquitously expressed redox protein involved in extracellular ligand-induced cell signaling. We previously reported that inducible whole-body Memo1 KO (cKO) mice displayed a syndrome of premature aging and disturbed mineral metabolism partially recapitulating the phenotype observed in Klotho or Fgf23-deficient mouse models. Here, we aimed at delineating the contribution of systemic mineral load on the Memo1 cKO mouse phenotype. We attempted to rescue the Memo1 cKO phenotype by depleting phosphate or vitamin D from the diet, but did not observe any effect on survival. However, we noticed that, by contrast to Klotho or Fgf23-deficient mouse models, Memo1 cKO mice did not present any soft-tissue calcifications and displayed even a decreased serum calcification propensity. We identified higher serum magnesium levels as the main cause of protection against calcifications. Expression of genes encoding intestinal and renal magnesium channels and the regulator epidermal growth factor were increased in Memo1 cKO. In order to check whether magnesium reabsorption in the kidney alone was driving the higher magnesemia, we generated a kidney-specific Memo1 KO (kKO) mouse model. Memo1 kKO mice also displayed higher magnesemia and increased renal magnesium channel gene expression. Collectively, these data identify MEMO1 as a novel regulator of magnesium homeostasis and systemic calcification propensity, by regulating expression of the main magnesium channels.

Development of a long acting FGF21 analogue-albumin fusion protein and its anti-diabetic effects

Fibroblast growth factor 21 (FGF21) is a hormone-like protein that improves blood glucose and lipid metabolism. However, its short half-life and instability are bottlenecks to its clinical applications. In this study, to extend its pharmacological action, we created a stabilized mutant FGF21 (mFGF21:ΔHPIP, P171G, A180E, L118C-A134C, S167A) and then genetically fused it with human albumin (HSA-mFGF21) via a polypeptide linker. Physicochemical analyses suggested that HSA-mFGF21 was formed from both intact HSA and mFGF21. Pharmacokinetic findings indicated the half-life of HSA-mFGF21 was 20 times longer than that of FGF21. In addition, HSA-mFGF21 was persistently distributed in adipose tissue as a target tissue. The in vivo hypoglycemic activity of HSA-mFGF21 using streptozotocin (STZ)-induced type I diabetes model mice, in which insulin secretion was suppressed, showed that a single intravenous administration of HSA-mFGF21 rapidly alleviated hyperglycemia. At that time, HSA-mFGF21 increased GLUT1 mRNA expression in adipose tissue without having any effect on insulin secretion. A twice weekly administration of HSA-mFGF21 continuously suppressed blood glucose levels and ameliorated the abnormalities of adipose tissue induced by STZ treatment. Interestingly, HSA-mFGF21 showed no hypoglycemic effects in healthy mice. Together, HSA-mFGF21 could be a novel biotherapeutic for the treatment of metabolic disorders including diabetes mellitus.

Analytical and clinical validation of rapid chemiluminescence enzyme immunoassay for urinary thioredoxin, an oxidative stress-dependent early biomarker of acute kidney injury

BACKGROUND

Oxidative stress is now recognized to be an important therapeutic target in kidney diseases. However, there are currently no biomarkers that can be used clinically to diagnose renal oxidative stress.

METHODS

A rapid assay system for urinary thioredoxin 1, an oxidative stress-dependent biomarker of acute kidney injury (AKI), was developed as a chemiluminescence enzyme immunoassay and validated analytically and clinically.

RESULTS

Analytic evaluation revealed that hemolytic hemoglobin caused measurements to be abnormally high, above the detectable range. However, urine sediment containing red blood cells did not affect the measurements. Assays using our proposed chemiluminescence enzyme immunoassay were completed within as little as 6 min, whereas a conventional ELISA > 4 h. Aciduria <pH 6.0 led to a significant underestimation of thioredoxin 1 concentrations. However, the effects of aciduria were completely reversible with use of a buffer developed for pH adjustment. Urinary thioredoxin 1 was increased in patients with AKI, but was unaffected by extrarenal oxidative stress diseases, including hypoxemia and myocardial infarction, or by chronic kidney disease in which serum creatinine concentrations were comparable.

CONCLUSIONS

These results suggest that the chemiluminescent enzyme immunoassay system for urinary thioredoxin 1 enables rapid and specific diagnosis of AKI associated with oxidative stress.

Nephroprotective Role of Selenium Nanoparticles Against Glycerol-Induced Acute Kidney Injury in Rats

Acute kidney injury (AKI) is a clinical syndrome associated with the incidence of rhabdomyolysis (RM). The current study was carried out to evaluate whether selenium nanoparticles (SeNPs) can protect against the glycerol-induced AKI model. Rats were distributed into four equal groups (n = 7): the control group (G1), SeNPs group (G2), AKI group (G3), and SeNPs+AKI group (G4). Rats in G1 were intramuscularly injected with physiological saline (0.9% NaCl). Rats in G2 were gavaged with SeNPs (0.1 mg/kg) for 14 days. Rats in G3 were intramuscularly injected with 50% glycerol (10 ml/kg). Rats in G4 were administered with SeNPs for 14 days and then injected with glycerol, as in G3. Glycerol-injected rats showed a significant increase in the kidney relative weight, as well as in the serum urea, creatinine, Kim-1, and renal malondialdehyde, nitric oxide, TNF-α, IL-1β, cytochrome c, Bax, and caspase-3 levels. In addition, a significant decrease in glutathione, glutathione peroxidase, glutathione reductase, superoxide dismutase, and catalase was recorded in the renal tissue. Selenium nanoparticles reduced the biochemical, molecular, and histological changes produced by glycerol. Overall, our results suggest that selenium nanoparticles could be used to protect against AKI development via antioxidant, anti-inflammatory, and anti-apoptotic activities.

Carbon Monoxide Rescues the Developmental Lethality of Experimental Rat Models of Rhabdomyolysis-Induced Acute Kidney Injury

Many victims, after being extricated from a collapsed building as the result of a disaster, suffer from disaster nephrology, a term that is referred to as the crush syndrome (CS). Recommended treatments, which include dialysis or the continuous administration of massive amounts of fluid are not usually easy in cases of such mass natural disasters. In the present study, we examined the therapeutic performance of a biomimetic carbon monoxide (CO) delivery system, CO-enriched red blood cells (CO-RBCs), on experimental animal models of an acute kidney injury (AKI) induced by traumatic and nontraumatic rhabdomyolysis, including CS and rhabdomyolysis with massive hemorrhage shock. A single CO-RBC treatment was found to effectively suppress the pathogenesis of AKI with the mortality in these model rats being improved. In addition, in further studies using glycerol-induced rhabdomyolysis model rats, the pathogenesis of which is similar to that for the CS, AKI and mortality were also reduced as the result of a CO-RBC treatment. Furthermore, CO-RBCs were found to have renoprotective effects via the suppression of subsequent heme protein-associated renal oxidative injury; the oxidation of myoglobin in the kidneys, the generation of reactive oxygen species by free heme produced from degraded-cytochrome P450 and hemoglobin-associated renal injury. Because CO-RBCs can be prepared and used at both hospitals and at a disaster site, these findings suggest that CO-RBCs have the potential for use as a novel cell therapy against both nontraumatic and traumatic rhabdomyolysis including CS-induced AKI. SIGNIFICANCE STATEMENT: After mass natural and man-made disasters, people who are trapped in collapsed buildings are in danger of acute kidney injury (AKI), including crush syndrome (CS)-related AKI. This paper reports that carbon monoxide-enriched red blood cells (CO-RBCs), which can be prepared at both hospitals and disaster sites, dramatically suppressed the pathogenesis of CS-related AKI, thus improving mortality via suppressing heme protein-associated renal injuries. CO-RBCs have the potential for serving as a practical therapeutic agent against disaster nephrology associated with the CS.

rA1M-035, a Physicochemically Improved Human Recombinant α1-Microglobulin, Has Therapeutic Effects in Rhabdomyolysis-Induced Acute Kidney Injury

AIMS

Human α₁-microglobulin (A1M) is an endogenous reductase and radical- and heme-binding protein with physiological antioxidant protective functions. Recombinant human A1M (rA1M) has been shown to have therapeutic properties in animal models of preeclampsia, a pregnancy disease associated with oxidative stress. Recombinant A1M, however, lacks glycosylation, and shows lower solubility and stability than A1M purified from human plasma. The aims of this work were to (i) use site-directed mutagenesis to improve the physicochemical properties of rA1M, (ii) demonstrate that the physicochemically improved rA1M displays full in vitro cell protective effects as recombinant wild-type A1M (rA1M-wt), and (iii) show its therapeutic potential in vivo against acute kidney injury (AKI), another disease associated with oxidative stress.

RESULTS

A novel recombinant A1M-variant (rA1M-035) with three amino acid substitutions was constructed, successfully expressed, and purified. rA1M-035 had improved solubility and stability compared with rA1M-wt, and showed intact in vitro heme-binding, reductase, antioxidation, and cell protective activities. Both rA1M-035 and rA1M-wt showed, for the first time, potential in vivo protective effects on kidneys using a mouse rhabdomyolysis glycerol injection model of AKI.

INNOVATION

A novel recombinant A1M-variant, rA1M-035, was engineered. This protein showed improved solubility and stability compared with rA1M-wt, full in vitro functional activity, and potential protection against AKI in an in vivo rhabdomyolysis mouse model.

CONCLUSION

The new rA1M-035 is a better drug candidate than rA1M-wt for treatment of AKI and preeclampsia in human patients.

IGFBP2 is a potential biomarker in acute kidney injury (AKI) and resveratrol-loaded nanoparticles prevent AKI

This study aims to determine whether insulin-like growth factor binding protein2 (IGFBP2) is a useful biomarker for early diagnosis of acute kidney injury (AKI), evaluate the therapeutic effects of resveratrol-loaded nanoparticles (Res-NPs), and investigate the possible underlying mechanisms in a rat model of AKI induced by IRI. Forty male Sprague–Dawley rats were randomly divided into four groups (10 animals per group): sham, IRI control, resveratrol, and Res-NPs injection. Kidney injury and the effects of Resveratrol and Res-NPs were determined by histological examination, renal function, cell apoptosis profile, and gene expression. Changes in IGFBP2 were similar with the pattern of well-known renal biomarkers, namely, kidney injury molecule 1 and neutrophil gelatinase-associated lipocalin, in all groups. Compared with the IRI control and resveratrol groups, the Res-NPs groups displayed significantly reduced apoptotic rate, reactive oxygen species level, and malondialdehyde content, downregulated protein expression levels of Caspase3 and Bax with increased antioxidant glutathione peroxidase level, and upregulated expression of Bcl-2 protein. Thus, IGFBP2 may serve as a promising novel biomarker of AKI, and Res-NPs may prevent kidney injury from ischemia/reperfusion in a rat model.

The Preventive Role of Pioglitazone in Glycerol-Induced Acute Kidney Injury in Rats during Two Different Treatment Periods

BACKGROUND

Acute kidney injury is the most life-threatening complication of rhabdomyolysis. Glycerol is commonly used to induce this injury. The aim was to investigate the renoprotective effects of pioglitazone and the possible advantage of administering the drug for a longer period.

METHODS

Twenty-four male Albino Wistar rats were randomly divided into 4 groups (n=6/group): (A) control, (B) glycerol (50%, 10 mL/kg intramuscularly), (C) glycerol+pioglitazone (10 mg/kg orally for 3 days), and (D) glycerol+pioglitazone (for 6 days). Serum urea and creatinine levels were measured to assess the renal function. Reduced glutathione (GSH) levels and histological alterations were also measured. Statistical analysis was performed using Prism (version 6). The numerical data were evaluated by ANOVA, followed by the Tukey tests. The categorical data were evaluated by the Mann-Whitney test and the Fisher exact tests. P<0.05 was considered significant.

RESULTS

In the glycerol-injected rats, the serum urea and creatinine levels were increased (P<0.001), while the GSH levels were decreased (P<0.001) compared to Group A. The nephrotoxicity showed significant tubular (P=0.01) and glomerular (P=0.02) injuries. In the pioglitazone-treated rats, the changes in the serum biomarkers and in the GSH levels were reversed in Group C (P=0.01) and in Group D (P=0.01). The microscopic examinations of the kidneys also showed some improvement. No obvious statistically significant difference was found between these 2 preventive groups in most studied features.

CONCLUSION

These results indicate that pioglitazone might have nephroprotective effects in this injury model. Pioglitazone succeeded in producing this effect within 3 days. Doubling the drug administration period did not produce any significant superior benefit.

Thioredoxin-albumin fusion protein prevents copper enhanced zinc-induced neurotoxicity via its antioxidative activity

Zinc (Zn) is a co-factor for a vast number of enzymes, and functions as a regulator for immune mechanism and protein synthesis. However, excessive Zn release induced in pathological situations such as stroke or transient global ischemia is toxic. Previously, we demonstrated that the interaction of Zn and copper (Cu) is involved in the pathogenesis of Alzheimer's disease and vascular dementia. Furthermore, oxidative stress has been shown to play a significant role in the pathogenesis of various metal ions induced neuronal death. Thioredoxin-Albumin fusion (HSA-Trx) is a derivative of thioredoxin (Trx), an antioxidative protein, with improved plasma retention and stability of Trx. In this study, we examined the effect of HSA-Trx on Cu²⁺/Zn²⁺-induced neurotoxicity. Firstly, HSA-Trx was found to clearly suppress Cu²⁺/Zn²⁺-induced neuronal cell death in mouse hypothalamic neuronal cells (GT1-7 cells). Moreover, HSA-Trx markedly suppressed Cu²⁺/Zn²⁺-induced ROS production and the expression of oxidative stress related genes, such as heme oxygenase-1. In contrast, HSA-Trx did not affect the intracellular levels of both Cu²⁺ and Zn²⁺ after Cu²⁺/Zn²⁺ treatment. Finally, HSA-Trx was found to significantly suppress endoplasmic reticulum (ER) stress response induced by Cu²⁺/Zn²⁺ treatment in a dose dependent manner. These results suggest that HSA-Trx counteracted Cu²⁺/Zn²⁺-induced neurotoxicity by suppressing the production of ROS via interfering the related gene expressions, in addition to the highly possible radical scavenging activity of the fusion protein. Based on these findings, HSA-Trx has great potential as a promising therapeutic agent for the treatment of refractory neurological diseases.

Protective Effects of Ophiocordyceps lanpingensis on Glycerol-Induced Acute Renal Failure in Mice

Objective

Oxidative stress and immune response are associated with acute renal failure (ARF). Ophiocordyceps lanpingensis (OL) might be an antioxidant and immunopotentiator. In this study, we explored the protective effects of OL on glycerol-induced ARF.

Methods

Male mice were randomly divided into four groups, specifically, glycerol-induced ARF model group, low-dose OL-treated group (1.0 g/kg/d), high-dose OL-treated group (2.0 g/kg/d), and control group. Renal conditions were evaluated using kidney index, serum creatinine (Cr), blood urea nitrogen (BUN), and histological analysis. Rhabdomyolysis was monitored using creatine kinase (CK) level. Oxidative stress was determined using kidney tissue glutathione (GSH), malondialdehyde (MDA), and superoxide dismutase (SOD) levels. Immune status was evaluated using immune organ indices and immunoglobulin G (IgG) level.

Results

OL could relieve renal pathological injury and decrease the abnormal levels of kidney index, serum Cr, CK, BUN, and MDA, as well as increase the immune organ indices and the levels of IgG, GSH, and SOD. Treatment with a high dose of OL had more positive therapeutic effects on ARF than using a low dose of OL.

Conclusion

OL could ameliorate renal dysfunction in glycerol-induced ARF in mice by inhibiting oxidative stress and enhancing immune response.

Erythropoietin protects against rhabdomyolysis-induced acute kidney injury by modulating macrophage polarization

Erythropoietin (EPO) is a well-known hormone that is clinically used for the treatment of anemia. Very recently, an increasing body of evidence showed that EPO could still regulate bioactivities of macrophages. However, the details about the immunomodulatory effect of EPO on macrophages are not fully delineated, particularly in the setting of renal damages. Therefore, in the present study, we determined whether EPO could exert an impact on the dynamics of macrophages in a well-established model of rhabdomyolysis-induced acute kidney injury and explored the potential mechanisms. EPO was found to ameliorate kidney injuries by reducing macrophages recruitment and promoting phenotype switch toward M2 macrophages in vivo. It was also confirmed that EPO could directly suppress pro-inflammatory responses of M1 macrophages and promote M2 marker expression in vitro. Data indicated the possible involvement of Jak2/STAT3/STAT6 pathway in the augmentation of EPO on M2 polarization. These results improved the understanding of the immunoregulatory capacity of EPO on macrophages, which might optimize the therapeutic modalities of EPO.

Renoprotective effect of low-molecular-weight sulfated polysaccharide from the seaweed Laminaria japonica on glycerol-induced acute kidney injury in rats

We investigated the renal protective effect of low-molecular-weight sulfated polysaccharide (LMWSP) fractions extracted from Laminaria japonica on glycerol-induced acute kidney injury (AKI) in rats. Glycerol treatment significantly increased serum creatinine (SCr) and blood urea nitrogen (BUN) levels. Intraperitoneal injection of LMWSP fractions markedly decreased SCr and BUN levels and reduced renal swelling. The fraction of 1.0M NaCl displayed the best renal protective effect of all fractions in attenuating AKI and maintaining blood glucose.

Non-Transgenic Mouse Models of Kidney Disease

Animal models are essential tools to understand the mechanisms underlying the development and progression of renal disease and to study potential therapeutic approaches. Recently, interventional models suitable to induce acute and chronic kidney disease in the mouse have become a focus of interest due to the wide availability of genetically engineered mouse lines. These models differ by their damaging mechanism (cell toxicity, immune mechanisms, surgical renal mass reduction, ischemia, hypertension, ureter obstruction etc.), functional and histomorphological phenotype and disease evolution. The susceptibility to a damaging mechanism often depends on strain and gender. The C57BL/6 strain, the most commonly used genetic background of transgenic mice, appears to be relatively resistant against developing glomerulosclerosis, proteinuria and hypertension. This review serves to provide a comprehensive overview of interventional mouse models of acute and chronic kidney disease.