Modulation of inflammatory response by selective inhibition of cyclooxygenase-1 and cyclooxygenase-2 in acute kidney injury

Protective effects of D-005, a lipid extract from Acrocomia crispa fruits, against ischemia/reperfusion-induced acute kidney injury in rats

Background

Acute kidney injury (AKI) induced by renal ischemia/reperfusion (IR) is associated with enhanced production of reactive oxygen species in renal tissues. D-005, a lipid extract obtained from Acrocomia crispa fruit, has previously shown antioxidant effects. The aim of this work was to evaluate the effects of D-005 on renal IR-induced AKI in rats.

Methods

Rats were randomized into seven groups including a negative control group (vehicle) without AKI and six groups with renal IR-induced AKI as follows: a positive control (vehicle); D-005 treatment at 25, 100, 200, or 400 mg/kg; and dexamethasone at 3 mg/kg. All treatments were orally administered as single doses 1 hour before AKI induction. Biomarkers (serum creatinine, urea, and uric acid concentrations), oxidative variables, and histopathological AKI changes were evaluated in blood and kidney tissues.

Results

All D-005 doses protected against IR-induced AKI in rats by significantly decreasing biomarkers and histopathological AKI changes as assessed by reduced serum concentrations of creatinine, urea, and uric acid. In addition, all D-005 doses decreased tubular damage, as shown by fewer detached cells and casts in the tubular lumen. D-005 reversed oxidation disturbance markers by decreasing malondialdehyde and sulfhydryl group concentrations in plasma and in kidney homogenates and by increasing kidney catalase activity. Dexamethasone, the reference substance, protected against IR-induced AKI in rats by reducing biochemical and histological variables of renal damage in a similar manner.

Conclusion

Administration of single oral doses of D-005 markedly and significantly protected against renal IR-induced AKI, possibly due to its known antioxidant effects.

Neferine Attenuates Acute Kidney Injury by Inhibiting NF-κB Signaling and Upregulating Klotho Expression

Purpose: Morbidity associated with and mortality from acute kidney injury (AKI) is gradually increasing, and no efficient drug is available. We explored whether neferine, a bisbenzylisoquinoline alkaloid, attenuated AKI, and the possible mechanisms in play in vivo and in vitro.

Methods: We induced AKI using ischemia-reperfusion (I/R) or lipopolysaccharide (LPS) in vivo. C57 BL/6 male mice were randomized into two groups each containing four subgroups: control, neferine, I/R or LPS, and I/R or LPS + neferine. Mice were sacrificed 24 h after AKI induction and kidneys and sera were collected. NRK-52E cells were exposed to hypoxia/reoxygenation (H/R) or LPS in vitro.

Results: Neferine pretreatment significantly alleviated kidney functional loss and pathological damage. In the AKI mouse models induced by I/R or LPS, neferine inhibited the infiltration of inflammatory cells, including granulocytes and macrophages. Both in vivo and in vitro, neferine attenuated apoptosis, suppressed inflammatory cytokine production, decreased degradation of IκB-α, and inhibited nuclear translocation of NF-κB. Furthermore, it also upregulated Klotho expression in AKI.

Conclusion: Neferine mitigated renal injury in AKI models, perhaps by suppressing the activation of NF-κB and upregulating the expression of Klotho.

Effect of Combined Treatment of Ketorolac and Remote Ischemic Preconditioning on Renal Ischemia-Reperfusion Injury in Patients Undergoing Partial Nephrectomy: Pilot Study

We evaluated postoperative renal function in patients with/without combined therapy of ketorolac and remote ischemic preconditioning during partial nephrectomy. Sixteen patients were randomly allocated to either the ketorolac combined with RIPC group (KI, n = 8) or control group (n = 8). The KI group received both remote ischemic preconditioning before surgery and intravenous ketorolac of 1 mg/kg before renal artery clamping. Renal parameters were measured before induction, after anesthesia induction, and 2, 12, 24, 48, and 72 h after renal artery declamping. Acute kidney injury was assessed by Acute Kidney Injury Network criteria. The estimated glomerular filtration rate decreased in both groups, but then increased significantly at 48 h and 72 h after declamping only in the KI group compared to 24 h (p = 0.001 and p = 0.016). Additionally, it was higher at 48 h and 72 h after declamping in the KI group compared to the control group (p = 0.025 and p = 0.044). The incidence of acute kidney injury was significantly reduced in the KI group (13%) compared to the control group (83%) (p = 0.026). FE_Na was markedly increased at 2 h after declamping, and recovered in both groups, but it was more significant at 12 h after declamping in the KI group (p = 0.022). Urinary N-acetyl-1-β-D-glucosoaminidase and serum neutrophil gelatinase-associated lipocalin were similar (p = 0.291 and p = 0.818). There is a possibility that combined therapy of ketorolac and remote ischemic preconditioning prior to ischemia may alleviate renal dysfunction and reduce the incidence of acute kidney injury in patients undergoing partial nephrectomy.

Effects of a Single Dose of Parecoxib on Inflammatory Response and Ischemic Tubular Injury Caused by Hemorrhagic Shock in Rats

Parecoxib, a selective COX-2 inhibitor, is used to improve analgesia in postoperative procedures. Here we evaluated whether pretreatment with a single dose of parecoxib affects the function, cell injury, and inflammatory response of the kidney of rats subjected to acute hemorrhage. Inflammatory response was determined according to serum and renal tissue cytokine levels (IL-1α, IL-1β, IL-6, IL-10, and TNF-α). Forty-four adult Wistar rats anesthetized with sevoflurane were randomized into four groups: placebo/no hemorrhage (Plc/NH); parecoxib/no hemorrhage (Pcx/NH); placebo/hemorrhage (Plc/H); and parecoxib/hemorrhage (Pcx/H). Pcx groups received a single dose of intravenous parecoxib while Plc groups received a single dose of placebo (isotonic saline). Animals in hemorrhage groups underwent bleeding of 30% of blood volume. Renal function and renal histology were then evaluated. Plc/H showed the highest serum levels of cytokines, suggesting that pretreatment with parecoxib reduced the inflammatory response in rats subjected to hemorrhage. No difference in tissue cytokine levels between groups was observed. Plc/H showed higher percentage of tubular dilation and degeneration, indicating that parecoxib inhibited tubular injury resulting from renal hypoperfusion. Our findings indicate that pretreatment with a single dose of parecoxib reduced the inflammatory response and tubular renal injury without altering renal function in rats undergoing acute hemorrhage.

Prostaglandin E2 regulates renal function in C57/BL6 mouse with 5/6 nephrectomy

AIMS

To investigate the roles of cyclooxygenases (COX) and their metabolites in C57/BL6 mice with 5/6 nephrectomy, an animal model of chronic renal failure.

MAIN METHODS

C57/BL6 mice were grouped into sham-operated (2K), one kidney removal (1K) and 5/6 nephrectomy groups (5/6Nx). Renal resistive index was measured by ultrasonography. Blood, aortae, renal arteries and renal cortex were collected for measurement of kidney function, assessment of vascular responsiveness, Western blotting, immuohistochemistry and enzyme-linked immunosorbent assays.

KEY FINDINGS

After four weeks, acetylcholine-induced relaxations were blunted in renal arteries of 1K and 5/6Nx mice; indomethacin, a non-selective COX inhibitor, improved the response in 5/6Nx, but not in 1K renal arteries. In 5/6Nx renal arteries, but not in 1K preparations, the protein presence of endothelial nitric oxide synthase (eNOS) was decreased, while that of COX-2 and its products [prostacyclin and thromboxane A₂] were increased. The renal resistive index was lower in 5/6Nx mice, suggesting a lower resistance in the renal microvasculature. In the renal cortex of 5/6Nx mice, eNOS protein presence was increased; while the presence of COX-2 was not detectable. The prostaglandin E₂ level was lower in the 5/6Nx cortex than in the other two groups.

SIGNIFICANCE

The early stage of renal mass removal is associated with increased renal arterial constriction and reduced microvascular resistance. The former is due to downregulation of eNOS and upregulation of COX-2, leading to an increased production of prostacyclin and thromboxane A₂. A reduced production of PGE₂ in the renal cortex is important for maintaining normal renal function.

Obesity-associated cancer risk: the role of intestinal microbiota in the etiology of the host proinflammatory state

Obesity increases the risks of many cancers. One important mechanism behind this association is the obesity-associated proinflammatory state. Although the composition of the intestinal microbiome undoubtedly can contribute to the proinflammatory state, perhaps the most important aspect of host-microbiome interactions is host exposure to components of intestinal bacteria that stimulate inflammatory reactions. Systemic exposures to intestinal bacteria can be modulated by dietary factors through altering both the composition of the intestinal microbiota and the absorption of bacterial products from the intestinal lumen. In particular, high-fat and high-energy diets have been shown to facilitate absorption of bacterial lipopolysaccharide (LPS) from intestinal bacteria. Biomarkers of bacterial exposures that have been measured in blood include LPS-binding protein, sCD14, fatty acids characteristic of intestinal bacteria, and immunoglobulins specific for bacterial LPS and flagellin. The optimal strategies to reduce these proinflammatory exposures, whether by altering diet composition, avoiding a positive energy balance, or reducing adipose stores, likely differ in each individual. Biomarkers that assess systemic bacterial exposures therefore should be useful to (1) optimize and personalize preventive approaches for individuals and groups with specific characteristics and to (2) gain insight into the possible mechanisms involved with different preventive approaches.

Physiology and pathophysiology of cyclooxygenase-2 and prostaglandin E2 in the kidney

The cyclooxygenase (COX) enzyme system is the major pathway catalyzing the conversion of arachidonic acid into prostaglandins (PGs). PGs are lipid mediators implicated in a variety of physiological and pathophysiological processes in the kidney, including renal hemodynamics, body water and sodium balance, and the inflammatory injury characteristic in multiple renal diseases. Since the beginning of 1990s, it has been confirmed that COX exists in 2 isoforms, referred to as COX-1 and COX-2. Even though the 2 enzymes are similar in size and structure, COX-1 and COX-2 are regulated by different systems and have different functional roles. This review summarizes the current data on renal expression of the 2 COX isoforms and highlights mainly the role of COX-2 and PGE2 in several physiological and pathophysiological processes in the kidney.

Chronic Arachidonic Acid Administration Decreases Docosahexaenoic Acid- and Eicosapentaenoic Acid-Derived Metabolites in Kidneys of Aged Rats

Arachidonic acid (ARA) metabolites produced by cyclo-oxygenase and lipoxygenase are important mediators maintaining physiological renal function. However, the effects of exogenous ARA on kidney function in vivo remain unknown. This study examined the effects of long-term oral ARA administration on normal renal function as well as inflammation and oxidative stress in aged rats. In addition, we measured levels of renal eicosanoids and docosanoids using liquid chromatography–tandem mass spectrometry. Control or ARA oil (240 mg/kg body weight/day) was orally administered to 21-month-old Wistar rats for 13 weeks. Levels of plasma creatinine, blood urea nitrogen, inflammatory and anti-inflammatory cytokines, reactive oxygen species, and lipid peroxidation were not significantly different between the two groups. The ARA concentration in the plasma, kidney, and liver increased in the ARA-administered group. In addition, levels of free-form ARA, prostaglandin E₂, and 12- and 15-hydroxyeicosatetraenoic acid increased in the ARA-administered group, whereas renal concentration of docosahexaenoic acid and eicosapentaenoic acid decreased in the ARA-administered group. Levels of docosahexaenoic acid-derived protectin D1, eicosapentaenoic acid-derived 5-, and 18-hydroxyeicosapentaenoic acids, and resolvin E2 and E3 decreased in the ARA-administered group. Our results indicate that long-term ARA administration led to no serious adverse reactions under normal conditions and to a decrease in anti-inflammatory docosahexaenoic acid- and eicosapentaenoic acid-derived metabolites in the kidneys of aged rats. These results indicate that there is a possibility of ARA administration having a reducing anti-inflammatory effect on the kidney.

Protective effect of indomethacin in renal ischemia-reperfusion injury in mice

OBJECTIVE

To evaluate the renoprotection effects of non-steroidal anti-inflammatory drugs (NSAIDs) in renal ischemia-reperfusion injury (IRI) and the cyclooxygenase (COX)-1/2 blockade association by indomethacin (IMT) in the mice model.

METHODS

After the left renal pedicle of mice was clamped, IMT was administrated by intraperitoneal injection with four doses: 1, 3, 5, and 7 mg/kg. Blood and kidney samples were collected 24 h after IRI. The renal functions were assayed by the cytokines and serum creatinine (SCr) using enzyme-linked immunosorbent assay (ELISA) kits. Kidney samples were analyzed by hematoxylin and eosin (H&E) and immunohistochemistry stainings.

RESULTS

The mice administered with 5 mg/kg IMT had a marked reduction in SCr and significantly less tubular damage. The tumor necrosis factor α (TNF-α) activity in renal homogenates and interleukin 6 (IL-6) activity in serum had a marked reduction at doses of 5 and 7 mg/kg IMT. The administration of 3 and 5 mg/kg IMT had a marked reduction in the ratio of thromboxane B2 to 6-keto-prostaglandin F1α. COX-1 and COX-2 stainings were weaker in 5 mg/kg IMT groups than that in the other groups.

CONCLUSIONS

There was a dose response in the IMT function of renal IRI in mice, and IMT had a protective effect in a certain dose range. The effect of IMT on mice IRI was related to COX-1/2 blockades.

Phosphodiesterase type 5 inhibition attenuates cyclosporine A induced nephrotoxicity in mice

We investigated the renal protective effects of phophodiesterase type 5 (PDE5) inhibitors in mice with cyclosporine A (CyA; a calcineurin phosphatase inhibitor) induced nephrotoxicity. Fifty male mice were divided into five groups of 10. Group 1 received no treatment, group 2 received only saline orally, group 3 received 30 mg/kg/day CyA by subcutaneous injection, group 4 received only 30 mg/kg/day vardenafil orally, and group 5 received 30 mg/kg/day CyA by subcutaneous injection and 30 mg/kg/day vardenafil orally. At 28 days, platelet-derived growth factor A (PDGF-A) and C (PDGF-C), transforming growth factor-beta 1 (TGF-β1), cyclo-oxygenase 1 and 2 (COX-1 and COX-2), and P glycoprotein (Pgp) expression levels were measured in the renal tissues. In addition, expressions of COX-1 and COX-2 genes were determined using real-time PCR. PDE5 inhibitor administration ameliorated decreased PDGF-A and C, TGF-β1, COX-1 and -2, and Pgp expression levels by modulation of cyclic guanosine monophosphate (cGMP) activity in kidneys. The relative expressions of COX-1 and COX-2 genes to GAPDH revealed that the maximum increase was obtained in the group treated with CyA and vardenafil for both COX-1 and COX-2 genes. Our study revealed that long term oral treatment with vardenafil protects kidneys from CyA induced nephrotoxicity. We showed that long term oral treatment with PDE5 prevents pathological kidney changes caused by CyA induced nephrotoxicity.

The anti-oxidant effects are not the main mechanism for glutamine's protective effects on acute kidney injury in mice

Acute kidney injury (AKI) is a common problem characterized by an inflammatory response in the kidney and oxidative stress. However, there are no interventions to prevent AKI. Glutamine is an important precursor of glutathione and has also been shown to induce heat shock proteins (HSP). Thus, glutamine may affect both oxidative stress and inflammation. This study was to explore the effects of glutamine pretreatment on nephrotoxic AKI and to investigate the underlying mechanisms. First, the effects of alternate doses of glutamine were compared in CD-1 mice with AKI induced with folic acid intra-peritoneal injection. Then the effects of glutamine quercetin (an HSP inhibitor), and quercetin+glutamine, were compared in the same AKI model. AKI were assessed with plasma creatinine, urine neutrophil gelatinase-associated lipocalin, and renal histology. Inflammatory response was monitored with renal tumor necrosis factor (TNF-α), chemkines (CXCL1 and CCL2) contents, and neutrophil infiltration. Oxidative injury was detected with reduced glutathione, malondialdehyde, and protein thiol. Glutamine provided dose-dependent renal protection. Pretreatment with quercetin, which was showed to inhibit HSP-70 expression, abolished glutamine's renal-protective effects. Quercetin also abrogated glutamine's beneficial effects on renal TNF-α, chemokines, and neutrophil infiltration. However, quercetin did not affect glutamine's anti-oxidative effects. These results suggest that glutamine's renal-protective effects are mainly related to its activation of HSP-70, which mitigates inflammatory response, renal neutrophil infiltration and subsequent AKI. Regulating neutrophil infiltration might be a potential therapeutic target for AKI.

Pretreatment with paricalcitol attenuates inflammation in ischemia-reperfusion injury via the up-regulation of cyclooxygenase-2 and prostaglandin E2

BACKGROUND

The effect of paricalcitol on renal ischemia-reperfusion injury (IRI) has not been investigated. We examined whether paricalcitol is effective in preventing inflammation in a mouse model of IRI, and evaluated the cyclooxygenase-2 (COX-2) and prostaglandin E2 (PGE2) pathways as a protective mechanism of paricalcitol.

METHODS

Paricalcitol (0.3 μg/kg) was administered to male C57BL/6 mice 24 h before IRI. Bilateral kidneys were subjected to 23 min of ischemia, and mice were killed 72 h after IRI. The effects of paricalcitol on renal IRI were evaluated in terms of renal function, tubular necrosis, apoptotic cell death, inflammatory cell infiltration and inflammatory cytokines. The effects of paricalcitol on COX-2, PGE2 and its receptors were investigated.

RESULTS

Paricalcitol pretreatment improved renal function (decreased blood urea nitrogen and serum creatinine levels), tubular necrosis and apoptotic cell death in IRI-mice kidneys. The infiltration of inflammatory cells (T cells and macrophages), and the production of proinflammatory cytokines (RANTES, tumor necrosis factor-α, interleukin-1β and interferon-γ) were reduced in paricalcitol-treated mice with IRI. Paricalcitol up-regulated COX-2 expression, PGE2 synthesis and mRNA expression of receptor subtype EP4 in post-ischemic renal tissue. The cotreatment of a selective COX-2 inhibitor with paricalcitol restored functional injury and tubular necrosis in paricalcitol-treated mice with IRI.

CONCLUSIONS

Our study demonstrates that paricalcitol pretreatment prevents renal IRI via the inhibition of renal inflammation, and the up-regulation of COX-2 and PGE2 is one of the protective mechanisms of paricalcitol in renal IRI.

Hypoxia increases membranal and secreted HLA-DR in endothelial cells, rendering them T-cell activators

Transplantation involves preoperative ischemic periods that contribute to endothelial cell (EC) dysfunction and T-cell activation, leading to graft rejection. As hypoxia is a major constituent of ischemia, we evaluated its effect on the ability of ECs to express HLA-DR, which is required for presentation of antigens to T cells, and by itself serves as an important target for allogeneic T cells. Primary human umbilical vein ECs (HUVEC) and the human endothelial cell line EaHy926 were incubated in normoxia or hypoxia (PO(2) < 0.3%). Hypoxia increased the membranal expression (by 4-6 fold, P < 0.01) and secretion (by sixfold, P < 0.05) of HLA-DR protein, without influencing the accumulation of its mRNA. Alternative splicing, attenuated trafficking, or shedding from the plasma membrane were not observed, but the lysosomal inhibitor bafilomycin A1 reduced HLA-DR secretion. Hypoxia-induced endothelial HLA-DR elevated and diminished the secretion of IL-2 and IL-10, respectively, from co-cultured allogeneic CD4(+) T cells in a HLA-DR-dependent manner, as demonstrated by the use of monoclonal anti-HLA-DR. Our results indicate a yet not fully understood post-translational mechanism(s), which elevate both membranal and soluble HLA-DR expression. This elevation is involved in allogeneic T-cell activation, highlighting the pivotal role of ECs in ischemia/hypoxia-associated injury and graft rejection.

MHC mismatch inhibits neurogenesis and neuron maturation in stem cell allografts

Background

The role of histocompatibility and immune recognition in stem cell transplant therapy has been controversial, with many reports arguing that undifferentiated stem cells are protected from immune recognition due to the absence of major histocompatibility complex (MHC) markers. This argument is even more persuasive in transplantation into the central nervous system (CNS) where the graft rejection response is minimal.

Methodology/Principal Findings

In this study, we evaluate graft survival and neuron production in perfectly matched vs. strongly mismatched neural stem cells transplanted into the hippocampus in mice. Although allogeneic cells survive, we observe that MHC-mismatch decreases surviving cell numbers and strongly inhibits the differentiation and retention of graft-derived as well as endogenously produced new neurons. Immune suppression with cyclosporine-A did not improve outcome but non-steroidal anti-inflammatory drugs, indomethacin or rosiglitazone, were able to restore allogeneic neuron production, integration and retention to the level of syngeneic grafts.

Conclusions/Significance

These results suggest an important but unsuspected role for innate, rather than adaptive, immunity in the survival and function of MHC-mismatched cellular grafts in the CNS.

Erythropoietin administration is associated with short-term improvement in glomerular filtration rate after ischemia-reperfusion injury

BACKGROUND

Erythropoietin (EPO) is a cytokine with organ-protective properties. We hypothesized that EPO could attenuate acute renal dysfunction and inflammation in a porcine model of ischemia-reperfusion (IR). Furthermore, we aimed to characterize the impact of EPO on systemic and renal hemodynamics, and renal oxygen consumption.

METHODS

Twenty-four pigs were randomly assigned to three groups: (1) EPO (5000 IU/kg) administered intravenously before IR (n=9), (2) placebo administered before IR (n=9), or (3) sham group, anesthetized and operated on only (n=6). IR was induced by clamping the left renal artery for 45 min. Hemodynamics and renal blood flow (RBF) were analyzed continuously. Glomerular filtration rate (GFR), renal oxygen consumption, and plasma cytokines (IL-1β, IL-6, IL-8, IL-10, and TNF-α) were analyzed hourly. Renal biopsies were analyzed for cytokine content and apoptosis.

RESULTS

GFR was higher during reperfusion in the EPO group than in the placebo group (P<0.01). No differences between the IR groups were found in hemodynamics, RBF, oxygen consumption, or renal apoptosis. The levels of TNF-α in the plasma (P=0.036) and the levels of TNF-α and IL-10 in the renal cortex (P=0.04 and P=0.01, respectively) were lower in the EPO group compared with the sham group.

CONCLUSION

EPO attenuated the renal dysfunction as estimated as GFR. This effect was not related to changes in the hemodynamics. The immunomodulatory effects of EPO were manifested as decreased levels of TNF-α and IL-10 in renal biopsies and TNF-α levels in plasma.

Chronic lithium treatment protects the rat kidney against ischemia/reperfusion injury: the role of nitric oxide and cyclooxygenase pathways

Ischemia/reperfusion injury is a major problem in renal transplantation. Several evidences represent lithium preconditioning effect against ischemia/reperfusion injury in various tissues. In this study our aim was to investigate the protective effect of chronic lithium administration on renal ischemia/reperfusion injury in rats. Ischemia/reperfusion injury was induced by clamping left renal pedicle for 60 min, 2 weeks after right nephrectomy. Lithium-treated animals received lithium-chloride in drinking water for 30days. In order to investigate the role of nitric oxide (NO) and cyclooxygenase (COX) pathways in renoprotective effect of lithium, N(ω)-nitro-L-arginine methyl ester hydrochloride (L-NAME, NO synthase inhibitor) and indomethacin (COX inhibitor) were used, respectively. Serum creatinine, blood urea nitrogen and renal histology were assessed 24h after inducing ischemia/reperfusion injury. Dimercaptosuccinic acid scan was also performed 48 h following operation. Chronic lithium treatment in ischemia/reperfusion injury groups significantly decreased creatinine (1.09±0.16 mg/dl), blood urea nitrogen (59.0±13.38 mg/dl), histological damage (7.83%±4.02%) and improved cortical function compared with non-lithium treated animals (4.45±0.44, 176.66±12.24 mg/dl and 83.5%±3.5%, respectively) (P<0.001). Either L-NAME or indomethacin administration partially reversed the protective effect of lithium, while simultaneous blockade of NO and COX pathways completely abolished lithium renoprotective effect. Our results indicate that lithium ameliorates renal ischemia/reperfusion injury through NO and/or COX pathways. We propose that lithium pre-treatment as a simple and practical intervention to boost the renal viability and function after ischemia/reperfusion injury may be promising in the setting of transplantation.