Molecular mechanisms of trauma-induced acute kidney injury: Inflammatory and metabolic insights from animal models

The degree of aortic occlusion in the setting of trauma alters the extent of acute kidney injury associated with mitochondrial preservation

Resuscitative endovascular balloon occlusion of the aorta (REBOA) is used to control noncompressible hemorrhage not addressed with traditional tourniquets. However, REBOA is associated with acute kidney injury (AKI) and subsequent mortality in severely injured trauma patients. Here, we investigated how the degree of aortic occlusion altered the extent of AKI in a porcine model. Female Yorkshire-cross swine (n = 16, 68.1 ± 0.7 kg) were anesthetized and had carotid and bilateral femoral arteries accessed for REBOA insertion and distal and proximal blood pressure monitoring. Through a laparotomy, a 6-cm liver laceration was performed and balloon inflation was performed in zone 1 of the aorta for 90 min, during which animals were randomized to target distal mean arterial pressures of 25 or 45 mmHg via balloon volume adjustment. Blood draws were taken at baseline, end of occlusion, and time of death, at which point renal tissues were harvested 6 h after balloon deflation for histological and molecular analyses. Renal blood flow was lower in the 25-mmHg group (48.5 ± 18.3 mL/min) than in the 45-mmHg group (177.9 ± 27.2 mL/min) during the occlusion phase, which recovered and was not different after balloon deflation. AKI was more severe in the 25-mmHg group, as evidenced by circulating creatinine, blood urea nitrogen, and urinary neutrophil gelatinase-associated lipocalin. The 25-mmHg group had increased tubular necrosis, lower renal citrate synthase activity, increased tissue and circulating syndecan-1, and elevated systemic inflammatory cytokines. The extent of renal ischemia-induced AKI is associated with the magnitude of mitochondrial biomass and systemic inflammation, highlighting potential mechanistic targets to combine with partial REBOA strategies to prevent AKI.NEW & NOTEWORTHY Large animal models of ischemia-reperfusion acute kidney injury (IR-AKI) are lacking. This report establishes a titratable IR-AKI model in swine in which a balloon catheter can be used to alter distal pressures experienced by the kidney, thus controlling renal blood flow. Lower blood flow results in greater renal dysfunction and structural damage, as well as lower mitochondrial biomass, elevated systemic inflammation, and vascular dysfunction.

Multicompartmental Trauma Induces Persistent Inflammation and Organ Injury

INTRODUCTION

Previous preclinical models of multicompartmental injury have investigated its effects for durations of less than 72 h and the long-term effects have not been defined. We hypothesized that a model of multicompartmental injury would result in systemic inflammation and multiorgan dysfunction that persists at 1 wk.

METHODS

Male and proestrus female Sprague-Dawley rats (n = 16/group) underwent polytrauma (PT) (unilateral right lung contusion, hemorrhagic shock, cecectomy, bifemoral pseudofractures) and were compared to naive controls. Weight, hemoglobin, plasma neutrophil gelatinase-associated lipocalin, and plasma toll-like receptor 4 were evaluated on days two and seven. Bilateral lungs were sectioned, stained and assessed for injury at day seven. Comparisons were performed in Graphpad with significance defined as ∗P <0.05.

RESULTS

Rats who underwent PT had significant weight loss and anemia at day 2 (P = 0.001) compared to naïve rats which persisted at day 7 (P = 0.001). PT rats had elevated plasma neutrophil gelatinase-associated lipocalin at day 2 compared to naïve (P <0.0001) which remained elevated at day 7 (P <0.0001). Plasma toll-like receptor 4 was elevated in PT compared to naïve at day 2 (P = 0.03) and day 7 (P = 0.01). Bilateral lungs showed significant injury in PT cohorts at day 7 compared to naïve (P <0.0004). PT males had worse renal function at day seven compared to females (P = 0.02).

CONCLUSIONS

Multicompartmental trauma induces systemic inflammation and multiorgan dysfunction without recovery by day seven. However, females demonstrate improved renal recovery compared to males. Long-term assessment of preclinical PT models are crucial to better understand and evaluate future therapeutic immunomodulatory and anti-inflammatory treatments.

Tiliacora triandra Leaf Powder Ethanolic Extract in Combination with Cisplatin or Gemcitabine Synergistically Inhibits the Growth of Cholangiocarcinoma Cells In Vitro and in Nude Mouse Xenograft Models

Background and Objectives: The treatments of cholangiocarcinoma (CCA) with Cisplatin (Cis) and Gemcitabine (Gem) often cause side effects and drug resistance. This study aimed to investigate the combined effects of Tiliacora triandra leaf powder ethanolic extract (TLPE) and Cis or Gem on CCA cells in vitro and in nude mouse xenografts. Materials and Methods: Antiproliferative activity was evaluated using MTT assay. Drug interaction was studied by Chou-Talalay method. Apoptosis induction and cell cycle arrest were analyzed by flow cytometry. Cell cycle and apoptosis regulating proteins were evaluated by western blot analysis. Results:Treatments with Cis or Gem in combination with TLPE significantly inhibited the growth of KKU-M213B and KKU-100 cells compared with single drug treatments. Synergistic drug interactions were observed with the dose reduction of Cis and Gem treatments. The safety of TLPE was demonstrated in vitro by the hemolytic assay. Synergistic combination treatments down-regulated Bcl2 and reduced the ratio of Bcl2/Bax in both CCA cells. TLPE enhanced tumor suppression of both Cis and Gem in nude mouse xenograft models. Combination treatments with Cis and TLPE reduced Cis toxicity, as demonstrated by the enhanced body weight change of the treated mice compared with the treatment with Cis alone. Furthermore, TLPE reduced hepatotoxicity caused by Gem treatment and reduced kidney and spleen toxicities caused by Cis treatment. Conclusion: These findings suggest that TLPE enhances the anticancer activity of Cis and Gem and reduces their toxicity both in vitro and in nude mouse xenograft models.

Mangiferin: the miraculous xanthone with diverse pharmacological properties

Mangiferin (1,3,6,7-tetrahydroxy-2-[3,4,5-trihydroxy-6-(hydroxymethyl) oxan-2-yl] xanthen-9-one) is a bioactive component derived primarily from the mango tree. Belonging to the Xanthone family, its structure allows it to engage with a variety of pharmacological targets. The symmetric linked core of xanthones has a heterogeneous biogenetic background. The carbon atoms are designated in a biochemical order, which reveals the reason of ring A (C1-C4) being referred to as acetate originated, and ring B (C5-C8) is referred to as shikimate originated. The antibacterial, hypocholesterolemic, antiallergic, cardiotonic, antidiabetic, anti-neoplastic, neuroprotective, antioxidant and immunomodulatory properties have all been demonstrated for the secondary metabolite. This study assessed and explained the important medical properties of mangiferin available in published literature, as well as its natural source, biosynthesis, absorption and bioavailability; multiple administration routes; metabolism; nanotechnology for enhanced efficacy of mangiferin and its toxicity, to aid the anticipated on-going potential of mangiferin as a novel diagnostic treatment.

Burn-Induced Acute Kidney Injury-Two-Lane Road: From Molecular to Clinical Aspects

Severe burn injuries lead to acute kidney injury (AKI) development, increasing the mortality risk up to 28-100%. In addition, there is an increase in hospitalization days and complications appearance. Various factors are responsible for acute or late AKI debut, like hypovolemia, important inflammatory response, excessive load of denatured proteins, sepsis, and severe organic dysfunction. The main measure to improve the prognosis of these patients is rapidly recognizing this condition and reversing the underlying events. For this reason, different renal biomarkers have been studied over the years for early identification of burn-induced AKI, like neutrophil gelatinase-associated lipocalin (NGAL), cystatin C, kidney injury molecule-1 (KIM-1), tissue inhibitor of metalloproteinase-2 (TIMP-2), interleukin-18 (IL-18), and insulin-like growth factor-binding protein 7 (IGFBP7). The fundamental purpose of these studies is to find a way to recognize and prevent acute renal injury progression early in order to decrease the risk of mortality and chronic kidney disease (CKD) onset.

Early Plasma Nuclear DNA, Mitochondrial DNA, and Nucleosome Concentrations Are Associated With Acute Kidney Injury in Critically Ill Trauma Patients

Circulating nucleic acids, alone and in complex with histones as nucleosomes, have been proposed to link systemic inflammation and coagulation after trauma to acute kidney injury (AKI). We sought to determine the association of circulating nucleic acids measured at multiple time points after trauma with AKI risk.

Small animal models of thermal injury

Burns are a severe form of trauma that account for 1.1 million cases necessitating medical attention and 4500 mortalities annually in the United States alone. Importantly, the initial trauma is succeeded by extensive, prolonged physiological alterations that detrimentally impact multiple organ systems. Given the complexity of post-burn pathophysiology, in vitro experiments are insufficient to model thermal injuries. Therefore, compatible animal burn models are essential for studying burn-related phenomena. In this chapter, we discuss commonly employed small animal burn models and their comparability and applicability to human studies. In particular, we compare post-burn wound healing between the species as well as relevant hypermetabolic and inflammatory characteristics, providing a better understanding of the pros and cons of utilizing a small animal surrogate for human burns. We further provide an overview of the rodent scald burn model methodology as well as a comparison between elderly, aged and young animals, providing a guide for tailoring animal model choice based on the relevant research question.

Overexpression of TRIM3 protects against LPS-induced acute kidney injury via repressing IRF3 pathway and NLRP3 inflammasome

PURPOSE

The pathological process of sepsis involves multiple system organs, including kidney. Sepsis-induced acute kidney injury (AKI) has high morbidity and high mortality. Overproduced inflammatory factors contribute to the occurrence and evolvement of AKI. Here, the role and underlying mechanism of tripartite motif containing 3 (TRIM3) and in AKI was explored.

METHODS

Lipopolysaccharide (LPS) was used for constructing AKI model both in vitro and in vivo. RT-PCR and western blot were performed to detect TRIM3, Interferon regulatory factor 3 (IRF3) and NLRP3-ASC-Caspase1 inflammasome. Upon selectively regulating the TRIM3 or IRF3 expression, the proliferation, apoptosis and inflammatory response were detected. The interaction between TRIM3 and IRF3 was verified by Immunoprecipitation (IP).

RESULTS

TRIM3 was down-regulated in mediated injury renal tubular epithelial cell line HK-2 treated with LPS. Overexpression of TRIM3 promoted cell viability and reduced apoptosis. In addition, overexpression of TRIM3 inhibited the expression of inflammatory factors (IL-1β, IL-6, TNF-α and IL-18), dampened the phosphorylation of IRF3 and repressed NLRP3 inflammasome activation. Furthermore, TRIM3 overexpression significantly eased the LPS-induced damage on AKI rat model and decreased the serum creatinine and urea nitrogen levels in rat kidney tissues. The results of immunohistochemistry (IHC) and Western blot manifested that TRIM3 was increased dramatically after TRIM3 was overexpressed in the rat kidney tissues, while IRF3 and NLRP3-ASC-Caspase1 inflammasome were significantly repressed following TRIM3 upregulation in the kidney tissues. Mechanistically, TRIM3 interacted with IRF3 and inhibited its phosphorylation.

CONCLUSION

Overexpression of TRIM3 protected against LPS-induced AKI by inhibiting the IRF3 pathway and NLRP3 inflammasome activation.

Large animal models for translational research in acute kidney injury

While extensive research using animal models has improved the understanding of acute kidney injury (AKI), this knowledge has not been translated into effective treatments. Many promising interventions for AKI identified in mice and rats have not been validated in subsequent clinical trials. As a result, the mortality rate of AKI patients remains high. Inflammation plays a fundamental role in the pathogenesis of AKI, and one reason for the failure to translate promising therapeutics may lie in the profound difference between the immune systems of rodents and humans. The immune systems of large animals such as swine, nonhuman primates, sheep, dogs and cats, more closely resemble the human immune system. Therefore, in the absence of a basic understanding of the pathophysiology of human AKI, large animals are attractive models to test novel interventions. However, there is a lack of reviews on large animal models for AKI in the literature. In this review, we will first highlight differences in innate and adaptive immunities among rodents, large animals, and humans in relation to AKI. After illustrating the potential merits of large animals in testing therapies for AKI, we will summarize the current state of the evidence in terms of what therapeutics have been tested in large animal models. The aim of this review is not to suggest that murine models are not valid to study AKI. Instead, our objective is to demonstrate that large animal models can serve as valuable and complementary tools in translating potential therapeutics into clinical practice.

Protective Effect of Calcium Dobesilate on Induced AKI in Severely Burned Mice

BACKGROUND

Early acute kidney injury (AKI) predicts a high mortality rate in severely burned patients. However, the pathophysiology of early AKI induced by severe burn has not been well-defined. This study was designed to examine the protective effects of calcium dobesilate (CaD) against severe burn-induced early AKI in mice and explore the mechanism.

METHODS

The shaved backs of mice were immersed in 100°C water for 10 s to make severe burn (40% of the total body surface area). CD-57 male mice were randomly divided into sham, burn, burn + vehicle, and burn + CaD groups. Renal function, reactive oxygen species generation, tubular necrosis, and phosphorylation of mitogen-activated protein kinase, protein kinase B (Akt), and nuclear factor (NF)-κB were measured at 24 and 48 h after the burn. Renal histology, ELISA, qRT-PCR, and Western blotting were performed on the renal tissue of mice to examine the effects and mechanisms at 24 and 48 h after the burn.

RESULTS

Tubular damage, cast formation, and elevations of serum creatinine, BUN, and renal tissue kidney injury molecule 1 levels were all observed in the burned mice, and these were all alleviated in the mice with CaD treatment. In addition, the levels of oxidation-reduction potential and malondialdehyde were decreased, while the activities of the endogenous antioxidative enzymes were increased in the kidney tissues from the mice after CaD treatment. Furthermore, the activities of Akt, p38, extracellular sign-regulated kinase, Jun N-terminal kinase, and NF-κB signaling were increased in the kidney of burned mice and normalized after CaD treatment.

CONCLUSION

This study has established, for the first time, the protective effect of CaD against early AKI in severely burned mice. CaD may exert its protective effect through alleviating oxidative stress, apoptosis, and inflammation, as well as modulating some signaling pathways in the kidney.

Minimal Effects of Intravenous Administration of Xenogeneic Adipose Derived Stem Cells on Organ Function in a Porcine 40%TBSA Burn Model

Adipose stem cells (ASCs) have shown therapeutic promise for various conditions, including burn injury. While ASCs have immunomodulatory properties, concerns exist over pro-coagulant activity after intravenous (IV) administration. In the present study, we examined IV human ASC delivery in terms of coagulation, organ function, and inflammation in a 40% total body surface area (TBSA) swine burn model. Anesthetized female Yorkshire swine were burned and randomized to receive 15ml/kg Lactated Ringer's containing: no ASCs; a low dose (5x10 5 ASCs/kg), or a high dose (5x10 6 ASCs/kg). For biochemical analysis, blood was collected at baseline (BL), 3, 6, 12, and 24 hours post-burn, while kidney and liver tissue was collected post-euthanasia. A significant, but transient, effect of ASCs was seen on prothrombin times and INR, wherein low doses revealed slight hypercoagulation. Burns increased partial thromboplastin time, fibrinogen, and d-dimer levels, which was unchanged with ASC administration. ASCs tended to exacerbate increases in bilirubin at 3 hours, but this didn't reach statistical significance. A significant effect of ASCs on creatinine and BUN was seen, wherein low doses elevated levels at 24 hours (creatinine, p=0.0012; BUN, p=0.0195). Hepatic and renal TUNEL staining were similar for all groups. A dose-dependent decrease in IL-8 was observed, while low doses significantly increased IL-1RA at 3 (p=0.050), IL-12 at 12 (p=0.021) and IL-6 at 24 hours post-burn (p=0.035). IV administration of xenogeneic ASCs slightly increased coagulation, but effects on burn-induced renal and hepatic dysfunction effects were minimal. Despite some significant immunomodulation, organ dysfunction effects were modest. Collectively, this study provides evidence to be skeptical about xenogeneic ASC administration in regards to burn.

The modulatory effect of taurine on benzo (a) pyrene-induced hepatorenal toxicity

Toxicities linked with Benzo (a) pyrene B[a]P exposure, particularly in liver and kidney have been reported in both animals and humans. Taurine (2-aminoethane sulfonic acid) is an intracellular β-amino acid reported to elicit hepatorenal protective functions. However, the modulatory effect of taurine on hepatorenal toxicity associated with exposure to B[a]P has not been reported. This study evaluated the effects of taurine on the hepatorenal toxicities induced in cohorts of rats exposed to B[a]P. Experimental rats were treated as follows: B[a]P (10 mg/kg); co-treated cohorts -B[a]P (10 mg/kg) plus taurine (100 or 200 mg/kg) for 4 successive weeks. Results show that co-dosing with taurine significantly (P < 0.05) improved B[a]P-induced distortion of oxidative stress markers (catalase, superoxide dismutase, glutathione S-transferase, glutathione peroxidase, total sulphydryl, reduced glutathione, lipid peroxidation and xanthine oxidase), renal function (urea and creatinine) and liver function marker enzymes (alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase and gamma glutamyl transferase). Moreover, taurine effectively mitigated increase in myeloperoxidase activity, levels of reactive oxygen and nitrogen species, nitric oxide and interleukin-1β in kidney and liver of rats treated with B[a]P. In conclusion, taurine modulates hepatorenal toxicity in B[a]P-exposed rats by suppressing hepatic and renal damage indices, oxidative injury and inflammatory stress.

Endoplasmic Reticulum Stress-Activated PERK-eIF2α-ATF4 Signaling Pathway is Involved in the Ameliorative Effects of Ginseng Polysaccharides against Cisplatin-Induced Nephrotoxicity in Mice

Although previous studies have reported that saponins (ginsenosides, the major active and most representative ingredients in Panax ginseng C.A. Meyer) exerted a good ameliorative effect on cisplatin (CP)-induced acute kidney injury in animal models, little attention has been paid to a large number of polysaccharides isolated and purified from ginseng. This work aimed to investigate the protective effect and the possible molecular mechanism of ginseng polysaccharide (WGP) on CP-induced kidney toxicology in mice. The results from biomarker analysis including serum creatinine (CRE) and blood urea nitrogen (BUN) confirmed the protective effect of WGP at 200 and 400 mg/kg on CP-induced renal-toxicology. We found that WGP reduces the apoptosis of kidney cells by inhibiting endoplasmic reticulum (ER) stress caused by CP, which is manifested by increased phosphorylation of PERK. In addition, the apoptosis-associated with caspase 3 activation in renal cells induced by CP was inhibited after administration of WGP, and the phosphorylation levels of PI3K and AKT were also reduced significantly. We also demonstrated that after exposure to CP, the unfolded protein response signaling pathway PERK-eIF2α-ATF4 axis was significantly activated, manifested by increased phosphorylation of eIF2α and increased expression of ATF4 and CHOP. Interestingly, the WGP administration improves this situation. Furthermore, the supplement of WGP inhibited the overexpression of nuclear factor-kappa B p65 (NF-κB p65) and tumor necrosis factor-α (TNF-α) caused by CP exposure. In short, for the first time, our findings indicated that WGP could effectively prevent CP-induced ER stress, inflammation, and apoptosis in renal cells, in part, by regulating the PI3K/AKT and PERK-eIF2α-ATF4 signaling pathways.

An Assessment of Research Priorities to Dampen the Pendulum Swing of Burn Resuscitation

On June 17 to 18, 2019, the American Burn Association, in conjunction with Underwriters Laboratories, convened a group of experts on burn resuscitation in Washington, DC. The goal of the meeting was to identify and discuss novel research and strategies to optimize the process of burn resuscitation. Patients who sustain a large thermal injury (involving >20% of the total body surface area [TBSA]) face a sequence of challenges, beginning with burn shock. Over the last century, research has helped elucidate much of the underlying pathophysiology of burn shock, which places multiple organ systems at risk of damage or dysfunction. These studies advanced the understanding of the need for fluids for resuscitation. The resultant practice of judicious and timely infusion of crystalloids has improved mortality after major thermal injury. However, much remains unclear about how to further improve and customize resuscitation practice to limit the morbidities associated with edema and volume overload. Herein, we review the history and pathophysiology of shock following thermal injury, and propose some of the priorities for resuscitation research. Recommendations include: studying the utility of alternative endpoints to resuscitation, reexamining plasma as a primary or adjunctive resuscitation fluid, and applying information about inflammation and endotheliopathy to target the underlying causes of burn shock. Undoubtedly, these future research efforts will require a concerted effort from the burn and research communities.

[Arctiin antagonizes triptolide-induced renal toxicity in rats via anti-inflammatory pathway]

OBJECTIVE

To investigate the protective effect of arctiin with anti-inflammatory bioactivity against triptolide-induced nephrotoxicity in rats and explore the underlying mechanism.

METHODS

Forty SD rats were divided into 4 groups for gastric lavage of normal saline, arctiin (500 mg/kg), triptolide (500 μg/kg), or both arctiin (500 mg/kg) and triptolide (500 μg/kg). Blood samples were collected for analysis of biochemical renal parameters, and the renal tissues were harvested for determining the kidney index and for pathological evaluation with HE staining. In the in vitro experiment, HK-2 cells were treated with arctiin and triptolide either alone or in combination, and the cell viability was determined with MTT assay; the cell morphological changes was observed using laser confocal microscopy, cell apoptosis was detected using flow cytometry, and the expressions of inflammation-related protein expression were detected by Western blotting.

RESULTS

In SD rats, arctiin significantly antagonized triptolide-induced elevation of BUN, Scr and kidney index (P < 0.05) and obviously improved renal tissue damages induced by triptolide including cell swelling, vacuolization and spotty necrosis. Arctiin significantly inhibited triptolide-induced cytotoxicity in HK-2 cells and increased the cell viability at 24 h (P < 0.05). Arctiin also attenuated triptolide-induced cell morphological changes, decreased cell apoptosis rate (P < 0.05) and reversed the expressions of IκBα and nuclear p65 (P < 0.05).

CONCLUSIONS

Arctiin can protect the kidney from triptolide-induced damages in rats possibly through the anti-inflammatory pathway.

A 30% incidence of renal cysts with varying sizes and densities in biomedical research swine is not associated with renal dysfunction

BACKGROUND

Renal cystic disease arising from various etiologies results in fluid-filled cavities within the kidneys. Moreover, preexisting renal dysfunction has been shown to exacerbate multiple pathologies. While swine bred for biomedical research are often clinically inspected for illness/parasites, more advanced diagnostics may aid in uncovering underlying renal abnormalities.

METHODS

Computed tomography was performed in 54 female prepubertal Yorkshire swine to characterize renal cysts; urine and blood chemistry, and histology of cysts were also performed.

RESULTS

Digital reconstruction of right and left kidneys demonstrated that roughly one-third of the animals (17/54; 31%) had one or more renal cyst. Circulating biomarkers of renal function were not different between animals that had cysts and those that did not. Alternatively, urinary glucose (P = .03) was higher and sodium (P = .07) tended to be lower in animals with cysts compared to animals without, with no differences in protein (P = .14) or potassium (P = .20). Aspiration of cystic fluid was feasible in two animals, which revealed that the cystic fluid urea nitrogen (97.6 ± 28.7 vs 911.3 ± 468.2 mg/dL), potassium (29.8 ± 14.4 vs 148.2 ± 24.85 mmol/L), uric acid (2.55 ± 1.35 vs 11.4 ± 5.65 mg/dL), and creatinine (60.34 ± 17.26 vs 268.99 ± 95.79 mg/dL) were much lower than in the urine. Histology demonstrated a cyst that markedly compresses the adjacent cortex and is lined by a single layer of flattened epithelium, bounded by fibrous connective tissue which extends into the parenchyma. There is tubular atrophy and loss in these areas.

CONCLUSION

This study provides valuable insight for future studies focusing on kidney function in swine bred for biomedical research.

Calcitonin Gene-Related Peptide Attenuates LPS-Induced Acute Kidney Injury by Regulating Sirt1

BACKGROUND Acute kidney injury (AKI) caused by sepsis is a very dangerous clinical complication. This study explored the effects of calcitonin gene-related peptides (CGRP) on AKI and its mechanisms. MATERIAL AND METHODS We cultured renal proximal tubular epithelial cells (HK-2 cells) and induced AKI models using LPS. Recombinant human CGRP was used to stimulate HK-2 cells and we detected markers of kidney injury (KIM-1 and NGAL) to determine the protective effect of CGRP on HK-2 cells. In addition, we constructed Sirt1-overexpressing lentivirus and small interfering RNA to increase or decrease Sirt1 expression in HK-2 cells to verify that CGRP protects HK-2 cells by regulating Sirt1. RESULTS After CGRP stimulation of HK-2 cells, LPS-induced HK-2 cell damage was significantly ameliorated, showing a decrease in the expression of KIM-1, NGAL, and inflammatory factors. In addition, Sirt1 was significantly increased in CGRP-stimulated HK-2 cells. After transfection of HK-2 cells with Lenti-Sirt1, inflammation and damage of HK-2 cells were both reduced, indicating that Sirt1 has a protective effect on HK-2 cells and can mediate the protective effect of CGRP on HK-2 cells. Therefore, the protective effect of CGRP on HK-2 cells was also attenuated after reducing Sirt1 in HK-2 cells. Finally, we used CGRP to treat LPS-induced mice and verified the protective effect of CGRP on mouse AKI. CONCLUSIONS CGRP has a significant anti-inflammatory effect. In the treatment of AKI, CGRP can increase the expression of Sirt1 to exert an anti-inflammatory effect and has a good protective effect on LPS-induced HK-2 cells.

Current Concepts on the Reno-Protective Effects of Phosphodiesterase 5 Inhibitors in Acute Kidney Injury: Systematic Search and Review

Acute kidney injury (AKI) is associated with increased morbidity, prolonged hospitalization, and mortality, especially in high risk patients. Phosphodiesterase 5 inhibitors (PDE5Is), currently available as first-line therapy of erectile dysfunction in humans, have shown a beneficial potential of reno-protection through various reno-protective mechanisms. The aim of this work is to provide a comprehensive overview of the available literature on the reno-protective properties of PDE5Is in the various forms of AKI. Medline was systematically searched from 1946 to November 2019 to detect all relevant animal and human studies in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement. In total, 83 studies were included for qualitative synthesis. Sildenafil is the most widely investigated compound (42 studies), followed by tadalafil (20 studies), icariin (10 studies), vardenafil (7 studies), zaprinast (4 studies), and udenafil (2 studies). Even though data are limited, especially in humans with inconclusive or negative results of only two clinically relevant studies available at present, the results of animal studies are promising. The reno-protective action of PDE5Is was evident in the vast majority of studies, independently of the AKI type and the agent applied. PDE5Is appear to improve the renal functional/histopathological alternations of AKI through various mechanisms, mainly by affecting regional hemodynamics, cell expression, and mitochondrial response to oxidative stress and inflammation.

Effect of Intravenous Fluid Volumes on the Adrenal Glucocorticoid Response After Burn Injury in Swine

Severe thermal injury induces metabolic and physiological stress, prompting a disruption in the hypothalamic-pituitary-adrenal axis. The objective of this study was to evaluate potential confounding effects of Lactated Ringer's (LR) resuscitation on adrenal damage and cortisol production following burn. Anesthetized swine were instrumented with jugular catheters and sustained 40% TBSA burns from brass probes heated to 100°C. Animals recovered to consciousness and received IV fluid resuscitation with LR at two different volumes: 15 ml/kg/d (limited volume [LV], n = 6) or 2 ml/kg/%TBSA/d (modified Brooke [MB], n = 6). Nonburned animals (Sham) were both oral and IV fluid restricted (S-FR, n = 4) to induce stress. Computed tomography (CT) angiographies were performed at baseline (BL) and 48 hours postburn, while blood and urine samples were collected at BL, 6, 24, and 48 hours postburn, with euthanasia at 48 hours for adrenal harvesting. Urinary cortisol was elevated following burn/surgery in all animals and returned back to BL in S-FR (404 ± 48 pg/mg creatinine) but not MB (1332 ± 176 pg/mg creatinine; P = .005) or LV (1223 ± 335 pg/mg creatinine; P = .07) by 48 hours. Gene expression of cleavage enzymes (3β-HSD, CYP17, CYP11, and CYP21) along the cortisol synthesis pathway showed minimal changes. Adrenal apoptosis (Terminal deoxynucleotidyl transferase dUTP nick-end labeling [TUNEL] staining) was greatest in the MB group (P ≤ .01) when compared to S-FR, partly due to elevations in c-Jun N-terminal kinase. Adrenal hemorrhaging was also greatest in MB animals, with no differences in tissue volume or wet-to-dry ratio. However, tissue levels of cytokines IL-1β, IL-10, and IL-12 were greatest in LV. Burn injury elevates urinary cortisol and compromises adrenal gland integrity, which is affected by IV fluid volume.

Increased oxidative phosphorylation in lymphocytes does not atone for decreased cell numbers after burn injury

The acute systemic inflammatory response syndrome (SIRS) and multiorgan dysfunction (MOD) that occur in large burn injuries may be attributed, in part, to immunosuppressive responses such as decreased lymphocytes. However, the mitochondrial bioenergetics of lymphocytes after severe burn injury are poorly understood. The purpose of this study was to examine mitochondrial function of lymphocytes following severe burns in a swine model. Anesthetized Yorkshire swine (n = 17) sustained 40% total body surface area full-thickness contact burns. Blood was collected at pre-injury (Baseline; BL) and at 24 and 48 h after injury for complete blood cell analysis, flow cytometry, cytokine analysis, and ficoll separation of intact lymphocytes for high-resolution mitochondrial respirometry analysis. While neutrophil numbers increased, a concomitant decrease was found in lymphocytes (P < 0.001) after burn injury, which was not specific to CD4⁺ or CD8⁺ lymphocytes. No changes in immune cell population were observed from 24 h to 48 h post-injury. IL 12-23 decreased while a transient increase in IL 4 was found from BL to 24h (P < 0.05). CRP progressively increased from BL to 24h (P < 0.05) and 48h (P < 0.001) post-injury. Routine and maximal mitochondrial respiration progressively increased from BL to 24h (P < 0.05) and 48 h post-injury (P < 0.001). No changes were found in leak respiration or residual oxygen consumption. When considering the reduction in lymphocyte number, the total peripheral lymphocyte bioenergetics per volume of blood significantly decreased from BL to 24h and 48h (P < 0.05). For the first time, we were able to measure mitochondrial activity in intact lymphocyte mitochondria through high-resolution respirometry in a severely burned swine model. Our data showed that the non-specific reduction in peripheral T cells after injury was larger than the increased mitochondrial activity in those cells, which may be a compensatory mechanism for the total reduction in lymphocytes. Additional studies in the metabolic activation of T cell subpopulations may provide diagnostic or therapeutic targets after severe burn injury.

CD28 deficiency attenuates primary blast-induced renal injury in mice via the PI3K/Akt signalling pathway

INTRODUCTION

Primary blast affects the kidneys due to direct shock wave damage and the production of proinflammatory cytokines without effective treatment. CD28 has been reported to be involved in regulating T cell activation and secretion of inflammatory cytokines. The aim of this study was to investigate the influence of primary blast on the kidney and the effect of CD28 in mice.

METHODS

A mouse model of primary blast-induced kidney injury was established using a custom-made explosive device. The severity of kidney injury was investigated by H&E staining. ELISA was applied to study serum inflammation factors' expression. Western blot assays were used to analyse the primary blast-induced inflammatory factors' expression in the kidney. Immunofluorescence analysis was used to examine the PI3K/Akt signalling pathway.

RESULTS

Histological examination demonstrated that compared with the primary blast group, CD28 deficiency caused a significant decrease in the severity of the primary blast-induced renal injury. Moreover, ELISA and western blotting revealed that CD28 deficiency significantly reduced the levels of interleukin (IL)-1β, IL-4 and IL-6, and increased the IL-10 level (p<0.05). Finally, immunofluorescence analysis indicated that PI3K/Akt expression also changed.

CONCLUSIONS

CD28 deficiency had protective effects on primary blast-induced kidney injury via the PI3K/Akt signalling pathway. These findings improve the knowledge on primary blast injury and provide theoretical basis for primary blast injury treatment.

Isolation and Characterization of Multipotent CD24+ Cells From the Renal Papilla of Swine

Over 100,000 patients in the United States are currently waiting for a kidney transplant. With just over 10,000 cadaveric kidneys transplanted annually, it is of the utmost importance to optimize kidney viability upon transplantation. One exciting avenue may be xenotransplantation, which has rejuvenated interest after advanced gene editing techniques have been successfully used in swine. Simultaneously, acute kidney injury (AKI) is associated with high morbidity and mortality and currently lacks effective treatment. Animal models have been used extensively to address both of these issues, with recent emphasis on renal progenitor cells (RPCs). Due to anatomical similarities to humans we aimed to examine progenitor cells from the renal papillae of swine kidneys. To do this, RPCs were dissected from the renal papillae of healthy swine. Cell surface marker expression, proliferation, and differentiation of the RPCs were tested in vitro. Additionally, a mixed lymphocyte reaction was performed to examine immunomodulatory properties. RPCs displayed spindle shaped morphology with limited self-renewing capacity. Isolated RPCs were positive for CD24 and CD133 at early passages, but lost expression with subsequent passaging. Similarly, RPCs displayed myogenic, osteogenic, and adipogenic differentiation capacities at passage 2, but largely lost this by passage 6. Lastly, direct contact of RPCs with human lymphocytes increased release of IL6 and IL8. Taken together, RPCs from the papilla of porcine kidneys display transient stem cell properties that are lost with passaging, and either represent multiple types of progenitor cells, or a multipotent progenitor population. In instances of ischemic insult, augmentation of/with RPCs may potentiate regenerative properties of the kidney. While the use of swine for transplantation and ischemia studies confers obvious advantages, the populations of different progenitor cell populations within pig kidneys warrants further investigation. Ultimately, while gene editing techniques enhance the potential for xenotransplantation of organs or cells, the ultimate success of this strategy may be determined by the (dis)similarities of RPCs from different species.

Mangiferin Ameliorates Cisplatin Induced Acute Kidney Injury by Upregulating Nrf-2 via the Activation of PI3K and Exhibits Synergistic Anticancer Activity With Cisplatin

Occurrence of oxidative stress is the principal cause of acute kidney injury induced by cisplatin. Mangiferin, a naturally occurring antioxidant molecule, is found to ameliorate several oxidative stress mediated pathophysiological conditions including cancer. Cisplatin induced cytotoxicity was measured in NKE cells by MTT assay and microscopic analysis. Induction of oxidative stress and regulation of proapoptotic molecules were subsequently investigated by using different spectrophotometric analyses, FACS and immunocytochemistry. Induction of nephrotoxicity was determined by analyzing different serum biomarkers and histological parameters in vivo using swiss albino mice. Activation of NF-κB mediated pro-inflammatory and caspase dependent signaling cascades were investigated by semi-quantitative RT-PCR and immunoblotting. Mangiferin was found to ameliorate cisplatin induced nephrotoxicity in vitro and in vivo by attenuating the induction of oxidative stress and upregulating Nrf-2 mediated pro-survival signaling cascades via the activation of PI3K. Additionally, mangiferin showed synergistic anticancer activity with cisplatin in cancer cell lines (MCF-7 and SKRC-45) and EAC cell induced solid tumor bearing experimental mice. The ameliorative effect of mangiferin is primarily attributed to its anti-oxidant and anti-inflammatory properties. It acts differentially in normal tissue cells and tumor cells by modulating different cell survival regulatory signaling molecules. For the first time, the study reveals a mechanistic basis of mangiferin action against cisplatin induced nephrotoxicity. Since Mangiferin shows synergistic anticancer activity with cisplatin, it can be considered as a promising drug candidate, to be used in combination with cisplatin.

Enteral resuscitation with oral rehydration solution to reduce acute kidney injury in burn victims: Evidence from a porcine model

Intravenous (IV) resuscitation of burn patients has greatly improved outcomes and become a cornerstone of modern burn care. However, the heavy fluids and vascular access required may not be feasible in austere environments, mass casualty, or delayed transport scenarios. Enteral resuscitation has been proposed for these situations; we sought to examine the effectiveness of this strategy on improving burn-induced kidney injury. Anesthetized Yorkshire swine sustaining 40% TBSA full-thickness contact burns were randomized to three groups (n = 6/group): fluid deprivation, ad libitum water access, or 70 mL/kg/d Oral Rehydration Salt solution (ORS). Urine and blood were collected at baseline (BL), 6, 12, 24, 32, and 48h post-burn, at which point tissue was harvested and CT angiography performed. Although fluid consumption by ad libitum and ORS groups were matched (132±54mL/kg versus 120±24mL/kg, respectively), ORS intake increased urine output compared with water and no water (47.3±9.0 mL/kg versus 16.1±2.5 mL/kg, and 24.5±1.7 mL/kg respectively). Plasma creatinine peaked 6h following burn (1.67±0.07mg/dL) in all animals, but at 48h was comparable to BL in animals receiving water (1.23±0.06mg/dL) and ORS (1.30±0.09mg/dL), but not fluid deprived animals (1.56±0.05mg/dL) (P<0.05). Circulating levels of blood urea nitrogen steadily increased, but also decreased by 48h in animals receiving enteral fluids (P<0.05). Water deprivation reduced renal artery diameter (-1.4±0.17mm), whereas resuscitation with water (-0.44±0.14 mm) or ORS maintained it (-0.63±0.20 mm;P< 0.02). Circulating cytokines IL-1β, IL-6, IFNγ, and GM-CSF were moderately elevated in the fluid-deprived group. Taken together, the data suggest that enteral resuscitation with ORS rescues kidney function following burn injury. Incorporating enteral fluids may improve outcomes in resource-poor environments and possibly reduce IV fluid requirements to prevent co-morbidities associated with over-resuscitation. Studies into different volumes/types of enteral fluids are warranted. While ORS has saved many lives in cholera-associated dehydration, it should be investigated further for use in burn patients.

Comparison of acute kidney injury of different etiology reveals in-common mechanisms of tissue damage

Acute kidney injury (AKI) is a syndrome of reduced glomerular filtration rate and urine production caused by a number of different diseases. It is associated with renal tissue damage. This tissue damage can cause tubular atrophy and interstitial fibrosis that leads to nephron loss and progression of chronic kidney disease (CKD). This review describes the in-common mechanisms behind tissue damage in AKI caused by different underlying diseases. Comparing six high-quality microarray studies of renal gene expression after AKI in disease models (gram-negative sepsis, gram-positive sepsis, ischemia-reperfusion, malignant hypertension, rhabdomyolysis, and cisplatin toxicity) identified 5,254 differentially expressed genes in at least one of the AKI models; 66% of genes were found only in one model, showing that there are unique features to AKI depending on the underlying disease. There were in-common features in the form of four genes that were differentially expressed in all six models, 49 in at least five, and 215 were found in common between at least four models. Gene ontology enrichment analysis could be broadly categorized into the injurious processes hypoxia, oxidative stress, and inflammation, as well as the cellular outcomes of cell death and tissue remodeling in the form of epithelial-to-mesenchymal transition. Pathway analysis showed that MYC is a central connection in the network of activated genes in-common to AKI, which suggests that it may be a central regulator of renal gene expression in tissue injury during AKI. The outlining of this molecular network may be useful for understanding progression from AKI to CKD.