Agonist of peroxisome proliferator-activated receptor-gamma, rosiglitazone, reduces renal injury and dysfunction in a murine sepsis model

APOA2: New Target for Molecular Hydrogen Therapy in Sepsis-Related Lung Injury Based on Proteomic and Genomic Analysis

Target biomarkers for H₂ at both the protein and genome levels are still unclear. In this study, quantitative proteomics acquired from a mouse model were first analyzed. At the same time, functional pathway analysis helped identify functional pathways at the protein level. Then, bioinformatics on mRNA sequencing data were conducted between sepsis and normal mouse models. Differential expressional genes with the closest relationship to disease status and development were identified through module correlation analysis. Then, common biomarkers in proteomics and transcriptomics were extracted as target biomarkers. Through analyzing expression quantitative trait locus (eQTL) and genome-wide association studies (GWAS), colocalization analysis on Apoa2 and sepsis phenotype was conducted by summary-data-based Mendelian randomization (SMR). Then, two-sample and drug-target, syndrome Mendelian randomization (MR) analyses were all conducted using the Twosample R package. For protein level, protein quantitative trait loci (pQTLs) of the target biomarker were also included in MR. Animal experiments helped validate these results. As a result, Apoa2 protein or mRNA was identified as a target biomarker for H₂ with a protective, causal relationship with sepsis. HDL and type 2 diabetes were proven to possess causal relationships with sepsis. The agitation and inhibition of Apoa2 were indicated to influence sepsis and related syndromes. In conclusion, we first proposed Apoa2 as a target for H₂ treatment.

Anti-Hyperglycemic Agents in the Adjuvant Treatment of Sepsis: Improving Intestinal Barrier Function

Intestinal barrier injury and hyperglycemia are common in patients with sepsis. Bacteria translocation and systemic inflammatory response caused by intestinal barrier injury play a significant role in sepsis occurrence and deterioration, while hyperglycemia is linked to adverse outcomes in sepsis. Previous studies have shown that hyperglycemia is an independent risk factor for intestinal barrier injury. Concurrently, increasing evidence has indicated that some anti-hyperglycemic agents not only improve intestinal barrier function but are also beneficial in managing sepsis-induced organ dysfunction. Therefore, we assume that these agents can block or reduce the severity of sepsis by improving intestinal barrier function. Accordingly, we explicated the connection between sepsis, intestinal barrier, and hyperglycemia, overviewed the evidence on improving intestinal barrier function and alleviating sepsis-induced organ dysfunction by anti-hyperglycemic agents (eg, metformin, peroxisome proliferators activated receptor-γ agonists, berberine, and curcumin), and summarized some common characteristics of these agents to provide a new perspective in the adjuvant treatment of sepsis.

Pioglitazone Ameliorates Acute Endotoxemia-Induced Acute on Chronic Renal Dysfunction in Cirrhotic Ascitic Rats

Endotoxemia-activated tumor necrosis factor (TNFα)/nuclear factor kappa B (NFκB) signals result in acute on chronic inflammation-driven renal dysfunction in advanced cirrhosis. Systemic activation of peroxisome proliferator-activated receptor gamma (PPARγ) with pioglitazone can suppress inflammation-related splanchnic and pulmonary dysfunction in cirrhosis. This study explored the mechanism and effects of pioglitazone treatment on the abovementioned renal dysfunction in cirrhotic rats. Cirrhotic ascitic rats were induced with renal dysfunction by bile duct ligation (BDL). Then, 2 weeks of pioglitazone treatment (Pio, PPAR gamma agonist, 12 mg/kg/day, using the azert osmotic pump) was administered from the 6th week after BDL. Additionally, acute lipopolysaccharide (LPS, Escherichia coli 0111:B4; Sigma, 0.1 mg/kg b.w, i.p. dissolved in NaCl 0.9%) was used to induce acute renal dysfunction. Subsequently, various circulating, renal arterial and renal tissue pathogenic markers were measured. Cirrhotic BDL rats are characterized by decreased mean arterial pressure, increased cardiac output and portal venous pressure, reduced renal arterial blood flow (RABF), increased renal vascular resistance (RVR), increased relative renal weight/hydroxyproline, downregulated renal PPARγ expression, upregulated renal inflammatory markers (TNFα, NFκB, IL-6, MCP-1), increased adhesion molecules (VCAM-1 and ICAM-1), increased renal macrophages (M1, CD68), and progressive renal dysfunction (increasing serum and urinary levels of renal injury markers (lipocalin-2 and IL-18)). In particular, acute LPS administration induces acute on chronic renal dysfunction (increasing serum BUN/creatinine, increasing RVR and decreasing RABF) by increased TNFα-NFκB-mediated renal inflammatory markers as well as renal M1 macrophage infiltration. In comparison with the BDL+LPS group, chronic pioglitazone pre-treatment prevented LPS-induced renal pathogenic changes in the BDL-Pio+LPS group. Activation of systemic, renal vessel and renal tissue levels of PPARγ by chronic pioglitazone treatment has beneficial effects on the endotoxemia-related TNFα/NFκB-mediated acute and chronic renal inflammation in cirrhosis. This study revealed that normalization of renal and renal arterial levels of PPARγ effectively prevented LPS-induced acute and chronic renal dysfunction in cirrhotic ascitic rats.

Dimethyl fumarate ameliorates endotoxin-induced acute kidney injury against macrophage oxidative stress

BACKGROUND

Characterized by macrophage infiltration, renal inflammation during septic acute kidney injury (AKI) reveals a ubiquitous human health problem. Unfortunately, effective therapies with limited side effects are still lacking. This study is aiming to elucidate the role of Dimethyl fumarate (DMF) in macrophages against oxidative stress of septic AKI.

METHODS

Balb/c mice were gavaged by 50 mg/kg DMF then injected with 10 mg/kg LPS by i.p. We examined LPS-induced renal dysfunction and histological features in murine kidneys. Raw264.7 macrophage cells were also treated with DMF and then induced by LPS. The mitotracker staining was used to follow mitochondria integrity by confocal microscopy. Flow cytometry measured the production of ROS by DCF-HDA and the expression of iNOS. Western blot detected the expression of Nrf-2 and Sirt1. Co-IP measured the interaction between Sirt1 and Nrf-2. Confocal microscopy observed the colocalization of Sirt1 and Nrf-2 in LPS-treated Raw264.7 macrophage cells.

RESULTS

DMF ameliorated murine LPS nephritis with reduced blood urea nitrogen and serum creatinine, as well as decreased the histological alterations compared to the normal control. DMF significantly inhibited the expression of iNOS and reduced the production of nitrite in Raw264.7 cells following LPS treatment. Our study also revealed the role of DMF in protecting against intracellular ROS accumulation and mitochondria dysfunction in LPS-induced nephritis. DMF facilitated colocalization and interaction between Sirt1 and Nrf-2 in LPS-treated cells.

CONCLUSIONS

This study showed that DMF alleviated LPS-induced nephritis, indicating protective effects of DMF on macrophage against oxidative stress induced by LPS potentially involving Nrf-2-mediated pathway.

Monophosphoryl lipid A pretreatment suppresses sepsis- and LPS-induced proinflammatory cytokine production in the medullary thick ascending limb

Sepsis is the leading cause of acute kidney injury in critically ill patients. Tumor necrosis factor-α (TNF-α) has been implicated in the pathogenesis of septic kidney injury; however, the sites and mechanisms of renal TNF-α production during sepsis remain to be defined. In the present study, we showed that TNF-α expression is increased in medullary thick ascending limbs (MTALs) of mice with sepsis induced by cecal ligation and puncture. Treatment with lipopolysaccharide (LPS) for 3 h in vitro also increased MTAL TNF-α production. Sepsis and LPS increased MTAL TNF-α expression through activation of the myeloid differentiation factor 88 (MyD88)-IL-1 receptor-associated kinase 1-ERK signaling pathway. Pretreatment with monophosphoryl lipid A (MPLA), a nontoxic immunomodulator that protects against bacterial infection, eliminated the sepsis- and LPS-induced increases in MTAL TNF-α production. The suppressive effect of MPLA on TNF-α was mediated through activation of a phosphatidylinositol 3-kinase-dependent pathway that inhibits MyD88-dependent ERK activation. This likely involves MPLA-phosphatidylinositol 3-kinase-mediated induction of Tollip, which negatively regulates the MyD88-ERK pathway by inhibiting activation of IL-1 receptor-associated kinase 1. These regulatory mechanisms are similar to those previously shown to mediate the effect of MPLA to prevent sepsis-induced inhibition of MTAL [Formula: see text] absorption. These results identify the MTAL as a site of local TNF-α production in the kidney during sepsis and identify molecular mechanisms that can be targeted to attenuate renal TNF-α expression. The ability of MPLA pretreatment to suppress MyD88-dependent ERK signaling in the MTAL during sepsis has the dual beneficial effects of protecting tubule transport functions and attenuating harmful proinflammatory responses.

Protective effect of rosiglitazone on chronic renal allograft dysfunction in rats

BACKGROUND

Chronic renal allograft dysfunction (CRAD) is the main condition affecting the long-term survival of renal allografts. Rosiglitazone, which is a peroxisome proliferator-activated receptor-γ (PPAR-γ) agonist, has been shown to exert antifibrotic and anti-inflammatory effects on some renal diseases. The present paper investigates the effect of rosiglitazone on CRAD using a murine model.

METHODS

The CRAD group received classical orthotopic F344-Lewis kidney transplantation. The treatment group was treated with rosiglitazone for 12 weeks following renal transplantation. The control subjects were uninephrectomized F344 and Lewis rats. Twelve weeks after the operation, the rats were harvested for renal function, histological, immunohistochemical and molecular biological analyses.

RESULTS

Rosiglitazone treatment effectively decreased urine protein excretion and preserved renal function in the CRAD rats. Administration of rosiglitazone also inhibited interstitial fibrosis and macrophage infiltration in the CRAD rat kidneys. Furthermore, rosiglitazone treatment inhibited TGF-β and NF-κB pathway activation, decreased collagen I, collagen IV, α-SMA, MCP-1, ICAM-1, TNF-α, and IL-1β expression, and increased E-cadherin expression in renal allograft tissues from the CRAD rats.

CONCLUSIONS

Rosiglitazone successfully attenuates the development of CRAD via inhibition of TGF-β signaling, the renal tubular epithelial-to-mesenchymal transition (EMT), and inflammation.

A review of the anti-inflammatory properties of antidiabetic agents providing protective effects against vascular complications in diabetes

The global prevalence of Type 2 diabetes mellitus and its associated complications are growing rapidly. Although the role of hyperglycemia is well recognized in the pathophysiology of diabetic complications, its exact underlying mechanisms are not fully understood. In this regard, accumulating evidence suggests that the role of inflammation appears pivotal, with studies showing that most diabetic complications are associated with an inflammatory response. Several classes of antidiabetic agents have been introduced for controlling glycemia, with evidence that these pharmacological agents may have modulatory effects on inflammation beyond their glucose-lowering activity. Here we review the latest evidence on the anti-inflammatory effects of commonly used antidiabetic medications and discuss the relevance of these effects on preventing diabetic complications.

Rosiglitazone Reduces Apoptosis and Inflammation in Lipopolysaccharide-Induced Human Umbilical Vein Endothelial Cells

BACKGROUND Although the peroxisome proliferator-activated receptor-g (PPARg) agonist rosiglitazone has significant anti-inflammatory properties, no scientific studies have provided new insights in its pharmacological properties with respect to acute respiratory distress syndrome (ARDS). The present investigation aimed to evaluate whether rosiglitazone can reduce apoptosis and inflammation in a lipopolysaccharide (LPS)-induced acute respiratory distress syndrome in vitro model. MATERIAL AND METHODS Human umbilical vein endothelial cells (HUVECs) were treated with 1 µg/ml LPS in the absence or presence of 10 µM rosiglitazone for 24 h. Cell viability was measured by MTT assay. Flow cytometry was used to examine the cell apoptosis and ROS production in HUVECs response to LPS and rosiglitazone. The levels of pro-inflammatory cytokine factors, including TNF-α, IL-6, CXCL12, and CXCR4, were measured by ELISA, real-time PCR, and Western blot assay, respectively. The expression of PPARg, Bcl-2, and Bax and the activity of JAK2 and STAT3 were also investigated by Western blot assay. RESULTS We found that rosiglitazone significantly inhibited LPS-induced cell apoptosis, ROS production, and inflammation in HUVECs. Furthermore, we found a significant reduction of JAK2/STAT3 activation and the Bax/Bcl-2 ratio in LPS-induced HUVECs response to rosiglitazone treatment. CONCLUSIONS Treatment with rosiglitazone can reduce apoptosis and inflammation in HUVECs induced by LPS.

Cytoprotective effect of aquaporin 1 against lipopolysaccharide-induced apoptosis and inflammation of renal epithelial HK-2 cells

Sepsis is the most common underlying disease of disseminated intravascular coagulation. Acute kidney injury is a common and serious complications of sepsis. In the present study, a lipopolysaccharide (LPS)-induced human proximal tubule cell line (HK-2 cells) was selected as an in vitro model of septic acute kidney injury. The aim of the present study was to investigate whether aquaporin 1 (AQP-1) has a cytoprotective role in LPS-induced HK-2 cells. HK-2 cells were treated with 0-16 µg/ml LPS for 0-24 h to establish the in vitro model of sepsis. The results demonstrated that AQP-1 levels were the lowest of the eight AQP genes expressed in LPS-induced HK-2 cells. Prior to LPS treatment, HK-2 cells were transfected with pcDNA-AQP-1 or small interfering-AQP-1 and cell counting kint-8 and flow cytometry assays were performed to assess cell viability and apoptosis rate, respectively. Changes in the expression of proinflammatory cytokines and chemokines, as well as important factors in the p38, extracellular signal-regulated kinase (ERK)1/2 and c-Jun N-terminal kinase (JNK) pathways, were assessed using reverse transcription-quantitative polymerase chain reaction, western blotting and ELISA, respectively. LPS treatment reduced viability, increased apoptosis and upregulated the expression of proinflammatory cytokines and chemokines in HK-2 cells. AQP-1 overexpression significantly reversed the effects of LPS and downregulated the expression of tumor necrosis factor-α, interleukin (IL)-8, IL-1β and monocyte chemoattractant protein-1. The p38, ERK1/2 and JNK pathways were activated by LPS; however, the p38 and ERK1/2 pathways were blocked in AQP-1-overexpressing cells. AQP-1 overexpression was demonstrated to confer a survival advantage to LPS-injured HK-2 cells by controlling cell viability, apoptosis and inflammation, possibly via modulation of the p38 and ERK1/2 pathways. The results of the present study suggest that AQP-1 may be an effective treatment for acute kidney injury caused by sepsis.

An Anti-Inflammatory PPAR-γ Agonist from the Jellyfish-Derived Fungus Penicillium chrysogenum J08NF-4

An investigation of the jellyfish-derived fungus Penicillium chrysogenum J08NF-4 led to the isolation of two new meroterpene derivatives, chrysogenester (1) and 5-farnesyl-2-methyl-1-O-methylhydroquinone (2), and four known farnesyl meroterpenes. Docking analysis of 1 showed that it binds to PPAR-γ in the same manner as the natural PPAR-γ agonist amorfrutin B (7). Compound 1 activated PPAR-γ in murine Ac2F liver cells and increased nuclear PPAR-γ protein levels in murine RAW 264.7 macrophages. Because one of the main biological functions of PPAR-γ agonists is to suppress inflammatory response, an in vitro study was performed to explore the anti-inflammatory potency of 1 and the mechanism involved. In RAW 264.7 macrophages, 1 inhibited phosphorylation of the NF-κB p65 subunit and suppressed the expression of the pro-inflammatory mediators iNOS, NO, COX-2, TNF-α, IL-1β, and IL-6. We propose 1 suppresses inflammatory responses by activating PPAR-γ and subsequently downregulating the NF-κB signaling pathway, thus reducing the expressions of pro-inflammatory mediators.

Peroxisome proliferator-activated receptor γ agonism attenuates endotoxaemia-induced muscle protein loss and lactate accumulation in rats

The peroxisome proliferator-activated receptor γ (PPARγ) agonist rosiglitazone (Rosi) appears to provide protection against organ dysfunction during endotoxaemia. We examined the potential benefits of Rosi on skeletal muscle protein maintenance and carbohydrate metabolism during lipopolysaccharide (LPS)-induced endotoxaemia. Sprague-Dawley rats were fed either standard chow (control) or standard chow containing Rosi (8.5 ± 0.1 mg·kg−1·day−1) for 2 weeks before and during 24 h continuous intravenous infusion of LPS (15 μg·kg−1·h−1) or saline. Rosi blunted LPS-induced increases in muscle tumour necrosis factor-α (TNF-α) and interleukin-6 (IL-6) mRNA by 70% (P<0.05) and 64% (P<0.01) respectively. Furthermore, Rosi suppressed the LPS-induced reduction in phosphorylated AKT and phosphorylated Forkhead box O (FOXO) 1 protein, as well as the up-regulation of muscle RING finger 1 (MuRF1; P<0.01) mRNA and the LPS-induced increase in 20S proteasome activity (P<0.05). Accordingly, LPS reduced the muscle protein:DNA ratio (∼30%, P<0.001), which Rosi offset. Increased muscle pyruvate dehydrogenase kinase 4 (PDK4) mRNA (P<0.001) and muscle lactate accumulation (P<0.001) during endotoxaemia were suppressed by Rosi. Thus, pre-treatment with Rosi reduced muscle cytokine accumulation and blunted muscle protein loss and lactate accumulation during endotoxaemia, and at least in part by reducing activation of molecular events known to increase muscle protein breakdown and mitochondrial pyruvate use.

The In Vitro and In Vivo Anti-Inflammatory Effects of a Phthalimide PPAR-γ Agonist

Previously, the authors found that 4-hydroxy-2-(4-hydroxyphenethyl) isoindoline-1,3-dione (PD1) (a phthalimide analogue) bound to and activated peroxisome proliferator-activated receptor-γ (PPAR-γ). Since PPAR-γ suppresses inflammatory responses, the present study was undertaken to investigate the anti-inflammatory effects of PD1. In lipopolysaccharide (LPS)-stimulated murine RAW264.7 macrophages, PD1 suppressed the inductions of pro-inflammatory factors, including inducible nitric oxide synthase (iNOS), nitric oxide (NO), cyclooxygenase 2 (COX-2), tumor necrosis factor α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6). Concomitantly, PD1 enhanced the expressions of anti-inflammatory factors, such as arginase-1 and interleukin-10 (IL-10), and suppressed LPS-evoked nuclear factor kappa B (NF-κB) p65 subunit phosphorylation in macrophages. In addition, PPAR-γ activated by PD1 was intensively translocated to the nucleus. These observations suggest that the anti-inflammatory mechanism of PD1 involves inhibition of the NF-κB pathway. In a subsequent in vivo animal experiment conducted using a carrageenan-induced acute inflammatory rat paw edema model, intraperitoneal injection of PD1 significantly reduced paw swelling. Histological analysis of rat paw tissue sections revealed less infiltration of immune cells in PD1-pretreated animals. These findings suggest that PD1 be viewed as a lead compound for the development of novel anti-inflammatory therapeutics.

Selective Insulin Resistance in the Kidney

Insulin resistance has been characterized as attenuation of insulin sensitivity at target organs and tissues, such as muscle and fat tissues and the liver. The insulin signaling cascade is divided into major pathways such as the PI3K/Akt pathway and the MAPK/MEK pathway. In insulin resistance, however, these pathways are not equally impaired. For example, in the liver, inhibition of gluconeogenesis by the insulin receptor substrate (IRS) 2 pathway is impaired, while lipogenesis by the IRS1 pathway is preserved, thus causing hyperglycemia and hyperlipidemia. It has been recently suggested that selective impairment of insulin signaling cascades in insulin resistance also occurs in the kidney. In the renal proximal tubule, insulin signaling via IRS1 is inhibited, while insulin signaling via IRS2 is preserved. Insulin signaling via IRS2 continues to stimulate sodium reabsorption in the proximal tubule and causes sodium retention, edema, and hypertension. IRS1 signaling deficiency in the proximal tubule may impair IRS1-mediated inhibition of gluconeogenesis, which could induce hyperglycemia by preserving glucose production. In the glomerulus, the impairment of IRS1 signaling deteriorates the structure and function of podocyte and endothelial cells, possibly causing diabetic nephropathy. This paper mainly describes selective insulin resistance in the kidney, focusing on the proximal tubule.

Rosiglitazone pretreatment protects against lipopolysaccharide-induced fetal demise through inhibiting placental inflammation

Peroxisome proliferator-activated receptor (PPAR)-γ is highly expressed in human and rodent placentas. Nevertheless, its function remains obscure. The present study investigated the effects of rosiglitazone, a PPAR-γ agonist, on LPS-induced fetal death. All pregnant mice except controls were intraperitoneally injected with LPS (150 μg/kg) daily from gestational day (GD)15 to GD17. As expected, maternal LPS injection caused placental inflammation and resulted in 63.6% fetal death in dams that completed the pregnancy. Interestingly, LPS-induced fetal mortality was reduced to 16.0% when pregnant mice were pretreated with RSG. Additional experiment showed that rosiglitazone pretreatment inhibited LPS-induced expressions of tumor necrosis factor (Tnf)-α, interleukin (Il)-1β, Il-6, macrophage inflammatory protein (Mip)-2 and keratinocyte-derived chemokine (Kc) in mouse placenta. Although rosiglitazone had little effect on LPS-evoked elevation of IL-10 in amniotic fluid, it alleviated LPS-evoked release of TNF-α and MIP-2 in amniotic fluid. Further analysis showed that pretreatment with rosiglitazone, which activated placental PPAR-γ signaling, simultaneously suppressed LPS-evoked nuclear factor kappa B (NF-κB) activation and blocked nuclear translocation of NF-κB p65 and p50 subunits in trophoblast giant cells of the labyrinth layer. These results provide a mechanistic explanation for PPAR-γ-mediated anti-inflammatory activity in the placentas. Overall, the present study provides additional evidence for roles of PPAR-γ as an important regulator of placental inflammation.

Chemical Profiles and Protective Effect of Hedyotis diffusa Willd in Lipopolysaccharide-Induced Renal Inflammation Mice

Protective effect of Hedyotis diffusa (H. diffusa) Willd against lipopolysaccharide (LPS)-induced renal inflammation was evaluated by the productions of cytokines and chemokine, and the bioactive constituents of H. diffusa were detected by the ultra-fast liquid chromatography-diode array detector-quadrupole-time of flight mass spectrometry (UFLC-DAD-Q-TOF-MS/MS) method. As the results showed, water extract of H. diffusa (equal to 5.0 g/kg body weight) obviously protected renal tissues, significantly suppressed the productions of tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, IL-6, and monocyte chemoattractant protein (MCP)-1, as well as significantly promoted the production of IL-10 in serum and renal tissues. According the chemical profiles of H. diffusa, flavonoids, iridoid glycosides and anthraquinones were greatly detected in serum from H. diffusa extract treatment mice. Two main chemotypes, including eight flavonoids and four iridoid glycosides were found in renal tissues from H. diffusa extract treatment mice. The results demonstrated that water extract of H. diffusa had protective effect on renal inflammation, which possibly resulted from the bioactive constituents consisting of flavonoids, iridoids and anthraquinones.

PPARγ-dependent anti-tumor and immunomodulatory actions of pioglitazone

Peroxisome proliferator-activated receptor-γ (PPARγ) has been reported to play important roles in carcinogenesis. The current study was carried out to assess the possible anti-tumor effects of pioglitazone (PIO), a PPARγ agonist, in a mouse mammary carcinoma model, i.e. a solid Ehrlich carcinoma (SEC). Effects of PIO on tumor-induced immune dysfunction, and the possibility that PIO may modulate the anti-tumor and immunomodulatory effects of doxorubicin (DOX) were also studied. The effects in tumor-bearing hosts of several doses of PIO (100 mg/kg, per os), with and without the added presence of DOX (2 mg/kg, IP), was investigated in vivo; end-points evaluated included assessment of tumor volume, splenic lymphocyte profiles/functionality, tumor necrosis factor (TNF)-α content, as well as apoptosis and expression of nuclear factor-κB (NF-κB) among the tumor cells. The data indicate that PIO induced significant anti-tumor activity against the SEC. PIO treatments also significantly mitigated both tumor- and doxorubicin-induced declines in immune parameters assessed here. Moreover, PIO led to decreased NF-κB nuclear expression, and, in doing so, appeared to chemo-sensitize these tumor cells to DOX-induced apoptosis. All pioglitazone-studied effects were antagonized by GW9662, a selective PPARγ antagonist.

Analysis of the gene expression profile of curcumin-treated kidney on endotoxin-induced renal inflammation

Acute or chronic kidney inflammation is closely related to the progress of kidney diseases. Curcumin, a yellow pigment present in the rhizome of turmeric (Curcuma longa L. Zingiberaceae), was found to be a potential anti-inflammatory agent. The present study aimed to investigate the effects and explore the protective mechanism of curcumin on lipopolysaccharide (LPS)-induced kidney inflammation in mice using gene chip and pathological technology. Nine SPF Kunming mice (aged 6-8 weeks, weighing 20-25 g) were divided into three groups. Saline and LPS were injected intraperitoneally in a normal control group and a model group, respectively. Mice in the treatment group were first injected with curcumin (5 mg/kg) for 3 days before being injected with LPS (5 mg/kg). Kidney tissues were harvested at 6 h after treatment. Parts of kidney were fixed with 10 % formaldehyde for HE, Periodic acid-Schiff staining, and immunohistochemistry. Affymetrix gene chips (mouse 430 chip) were used to detect the renal gene expression profile, and the results were analyzed using bioinformatics methods. The renal gene expression profile showed that there are 148 Affy IDs (up-down group) whose levels of gene expression were increased after LPS stimulation and decreased by curcumin treatment and that there are 133 Affy IDs (down-up group) exhibiting the opposite trend. In the differentially expressed genes of the up-down group, 21 Gene Ontology (GO) genes were selected by screening function (P ≤ 0.01). In the biological processes, most of the genes were found to be related to the genes of regulation of macrophage activation and macrophage activation-associated genes. In the cellular localization, there were four functional GO genes (P ≤ 0.01); in the molecular structure, there were seven functional GO genes (P ≤ 0.01). In the down-up group, there were functional GO genes (P ≤ 0.01) and one functional GO gene (P ≤ 0.01) in the biological process and the cellular localization, respectively. Macrophage infiltration could be observed as early as 6 h after LPS stimulation. Pretreatment with 5 mg/kg of curcumin significantly decreased the macrophage infiltration. At 6 h after LPS injection, significant decreased expression of M6PRBP-1 and NEDD-4 was observed in renal tissue. On the other hand, pretreatment with curcumin significantly increased renal M6PRBP-1 and NEDD-4 expression. In this study, we also found the signaling pathway and the possible target gene of the protective effects of curcumin on endotoxin-induced renal inflammation. The kidney gene expression profile in the inflammatory state was clarified by using gene chip technology. Furthermore, we confirmed that curcumin treatment can change the gene expression profile.

Tumor necrosis factor-α: regulation of renal function and blood pressure

Tumor necrosis factor-α (TNF-α) is a pleiotropic cytokine that becomes elevated in chronic inflammatory states such as hypertension and diabetes and has been found to mediate both increases and decreases in blood pressure. High levels of TNF-α decrease blood pressure, whereas moderate increases in TNF-α have been associated with increased NaCl retention and hypertension. The explanation for these disparate effects is not clear but could simply be due to different concentrations of TNF-α within the kidney, the physiological status of the subject, or the type of stimulus initiating the inflammatory response. TNF-α alters renal hemodynamics and nephron transport, affecting both activity and expression of transporters. It also mediates organ damage by stimulating immune cell infiltration and cell death. Here we will summarize the available findings and attempt to provide plausible explanations for such discrepancies.

PPARγ delivered by Ch-GNPs onto titanium surfaces inhibits implant-induced inflammation and induces bone mineralization of MC-3T3E1 osteoblast-like cells

OBJECTIVES

To deliver the efficacy and safety of Ch-GNPs (Chitosan gold nanoparticles) conjugated anti-inflammatory molecules peroxisome proliferator activated receptor gamma (PPARγ) on implant surface titanium (Ti) to reduce implant-induced inflammation.

MATERIALS AND METHODS

The Ch-GNPs were conjugated with the PPARγ cDNA through a coacervation process. Conjugation was cast over Ti surfaces by dipping, and cells were seeded on different sizes (6 × 6 × 0.1 cm and 1 × 1 × 0.1 cm; n = 3) of Ti surfaces. The size of Ch-GNPs and surface characterization of Ti was performed using UV-vis spectroscopy, TEM (Transmission electron microscopy) and EDX (energy-dispersive X-ray). The DNA conjugation and transfection capacity of Ch-GNPs were simultaneously confirmed by agarose gel electrophoresis, β-galactosidase staining, and immunoblotting.

RESULTS

The Ch-GNPs were well dispersed and spherical in shape, with average size around 10-20 nm. Ti surfaces coated with Ch-GNPs/LacZ, as transfection efficacy molecule, showed strong β-galactosidase staining in MC-3T3 E1 cells. Cells cultured on Ch-GNPs/PPARγ-coated Ti surfaces were able to inhibit implant-induced inflammation by simultaneously suppressing the expression of tumor necrosis factor- alpha (TNF-α), interleukin-1 beta (IL-1β), inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and matrix metalloproteinase-2 (MMP-2). The inhibition mechanism of Ch-GNPs/PPARγ was due to inhibition of both reactive oxygen species (ROS) and nitric oxide (NO) secretion (n = 3; P < 0.05). In addition, Ch-GNPs/PPARγ was able to increase expression of bone morphogenetic protein (BMP-7) and runt-related transcription factor-2 (RUNX-2). Furthermore, alkaline phosphatase activity (ALP) was also increased than that in control (n = 3; P < 0.01). Whereas, expression of receptor activator of NF-κB ligand (RANKL) was decreased.

CONCLUSIONS

The novel gene delivery materials, like Ch-GNPs, can carry the PPARγ cDNA into the required areas of the implant surfaces, thus aiding to inhibit inflammation and promote osteoblast function. Thus, the PPARγ on implant surfaces may promote its clinical application on peri-implantitis or periodontitis like diseases.

Immunomodulatory therapy for sepsis: an update

Currently the treatment mainstay of sepsis is early and appropriate antibiotic therapy, accompanied by aggressive fluid administration, the use of vasopressors when needed and the prompt initiation of measures to support each failing organ. Activated protein C and hydrocortisone, when used accordingly can affect mortality. As the pathophysiologic events that take place during sepsis are being elucidated, new molecules that target each step of those pathways are being tested. However, a lot of those molecules affect various mediators of the sepsis cascade including inflammatory cytokines, cellular receptors, nuclear transcription factors, coagulation activators and apoptosis regulators. Over the last decade, a multitude of clinical trials and animal studies have investigated strategies that aimed to restore immune homeostasis either by reducing inflammation or by stimulating the innate and adaptive immune responses. Antibiotics, statins and other molecules with multipotent immunomodulatory actions have also been studied in the treatment of sepsis.

Curcumin attenuates lipopolysaccharide-induced renal inflammation

Renal inflammation is the main pathological change in many acute and chronic kidney diseases. Curcumin, a yellow pigment present in the rhizome of turmeric (Curcuma longa L. Zingiberaceae), was found to be a potential anti-inflammatory agent. The present study aimed to investigate the effects of curcumin on the inflammation of mice kidney and cultured renal tubular epithelial cells (HK-2 cells) induced by lipopolysaccharide (LPS) and to explore the mechanism. Curcumin was injected intraperitoneally before LPS administration. Renal inflammation was assessed by evaluating monocyte chemoattractant protein-1 (MCP-1) expression and macrophage infiltration in renal tissue using immunohistochemical methods, and also by measuring renal MCP-1 mRNA level using Real-Time polymerase chain reaction (PCR). HK-2 cells were cultured to investigate the in vitro effect of curcumin against LPS-induced renal inflammation. The expression of MCP-1 and interleukin-8 (IL-8) mRNA was measured by Real-Time PCR. The expression of MCP-1 and IL-8 protein in supernatant was detected by enzyme-linked immunosorbent assay (ELISA). The activity of nuclear factor (NF)-κB was detected by electrophoretic mobility shift assay (EMSA). The results demonstrated that curcumin could inhibit LPS-induced renal MCP-1 mRNA expression. Curcumin also significantly inhibited the expression of MCP-1 and IL-2 mRNA in HK-2 cells, and partially inhibited the secretion of MCP-1 and IL-8. Furthermore, curcumin was found to inhibit the DNA-binding activity of NF-κB. The present study demonstrated that curcumin has a protective effect on LPS-induced experimental renal inflammation, and this effect might be attributed to its inhibitory effects on MCP-1 mRNA expression and DNA-binding activity of NF-κB. Hence, curcumin might be potentially useful in some kidney diseases by preventing renal inflammation.

The impact of diabetes on the pathogenesis of sepsis

Diabetes is associated with an increased susceptibility to infection and sepsis. Conflicting data exist on whether the mortality of patients with sepsis is influenced by the presence of diabetes, fuelling the ongoing debate on the benefit of tight glucose regulation in patients with sepsis. The main reason for which diabetes predisposes to infection appears to be abnormalities of the host response, particularly in neutrophil chemotaxis, adhesion and intracellular killing, defects that have been attributed to the effect of hyperglycaemia. There is also evidence for defects in humoral immunity, and this may play a larger role than previously recognised. We review the literature on the immune response in diabetes and its potential contribution to the pathogenesis of sepsis. In addition, the effect of diabetes treatment on the immune response is discussed, with specific reference to insulin, metformin, sulphonylureas and thiazolidinediones.

Propofol increases bone morphogenetic protein-7 and decreases oxidative stress in sepsis-induced acute kidney injury

BACKGROUND

Pro-inflammatory cytokines and free radicals damage renal tissue leading to acute kidney injury (AKI) during sepsis. Bone morphogenetic protein-7 (BMP-7) represses tumour necrosis factor (TNF)-α-induced inflammatory responses and protects kidney from injury. The sedative agent, propofol, has immunomodulatory and antioxidative properties. The present study investigated whether propofol could reduce AKI in caecal ligation and puncture (CLP) mice and the possible mechanism behind this.

METHODS

Mice were treated with propofol or saline immediately and 12 h after CLP surgery. Kidney injury, survival and cytokine expressions of CLP mice were observed 24 h after CLP surgery. In vitro, lipopolysaccharide (LPS)-stimulated rat mesangial cells (RMCs) or hydrogen peroxide (H(2)O(2))-exposed murine kidney epithelial cells (M1) were treated with propofol. The expression of BMP-7, TNF-α and monocyte chemotactic protein (MCP)-1 in CLP mice kidney, RMCs or M1 cells was determined by RT-PCR. Free radical generation and cell death of RMCs and M1 cells were analysed. Nuclear factor (NF)-κB and peroxisome proliferator-activated receptor (PPAR)-γ expressions in LPS-stimulated RMCs were determined by western blotting.

RESULTS

Propofol increased survival and ameliorated AKI in CLP mice. Propofol increased BMP-7 expression but decreased TNF-α and MCP-1 expressions in the kidney of CLP mice and LPS-stimulated RMCs. Propofol also inhibited free radical generation and cell death in LPS-stimulated RMCs and decreased the TNF-α expression and cell death in H(2)O(2)-exposed M1 cells. Moreover, propofol decreased NF-κB but increased PPAR-γ expression in LPS-stimulated RMCs.

CONCLUSIONS

Propofol treatment could protect kidney from sepsis-induced AKI by increasing BMP-7 expression, decreasing inflammatory cytokines and inhibiting oxidative stress.

Can we predict the effects of NF-kappaB inhibition in sepsis? Studies with parthenolide and ethyl pyruvate

BACKGROUND

Based partially on encouraging findings from preclinical models, interest has grown in therapeutic inhibition of NF-kappaB to limit inflammatory injury during sepsis. However, NF-kappaB also regulates protective responses, and predicting the net survival effects of such inhibition may be difficult.

OBJECTIVES

To highlight the caution necessary with this therapeutic approach, we review our investigations in a mouse sepsis model with parthenolide and ethyl pyruvate, two NF-kappaB inhibitors proposed for clinical study.

RESULTS

Consistent with published studies, parthenolide decreased NF-kappaB binding activity and inflammatory cytokine release from lipopolysaccharide (LPS) stimulated RAW 264.7 cells in vitro. In LPS-challenged mice (C57BL/6J), however, while both agents decreased lung and kidney NF-kappaB binding activity and plasma cytokines early (1-3 h), these measures were increased later (6-12 h) in patterns differing significantly over time. Furthermore, despite studying several doses of parthenolide (0.25-4.0 mg/kg) and ethyl pyruvate (0.1-100 mg/kg), each produced small but consistent decreases in survival which overall were significant (p < or = 0.04 for each agent).

CONCLUSION

While NF-kappaB inhibitors hold promise for inflammatory conditions such as sepsis, caution is necessary. Clear understanding of the net effects of NF-kappaB inhibitors on outcome will be necessary before such agents are used clinically.

Rosiglitazone prevents the progression of renal injury in DOCA-salt hypertensive rats

This study was designed to evaluate the possible renoprotective effects of rosiglitazone (RGT), a peroxisome proliferator-activated subtype gamma receptor agonist, in deoxycorticosterone acetate (DOCA)-salt hypertension and its role in endogenous endothelin-1 (ET-1) production and renal fibrosis associated with inflammation. Rats were implanted with DOCA strips (200 mg kg(-1)) at 1 week after unilateral nephrectomy. DOCA-salt rats received control diet with or without RGT (10 mg kg(-1) per day). Systolic blood pressure was measured by the tail-cuff method. Glomerulosclerosis and tubulointerstitial fibrosis were evaluated on kidney sections. The expression of ED-1, cyclooxygenase-2 (COX-2), heat shock protein-25 (HSP25) and transforming growth factor-beta1 (TGF-beta1) was determined in the kidney by semiquantitative immunoblotting. In DOCA-salt rats, systolic blood pressure was increased, whereas creatinine clearance decreased compared with controls, which were counteracted by RGT treatment. Tubular injury and glomerulosclerois in the histological study were prominent in DOCA-salt rats, which were counteracted by RGT treatment. ET-1 expression was increased in DOCA-salts rats, which was attenuated by RGT treatment. The expression of TGF-beta1, ED-1 and COX-2 was increased in DOCA-salt, which was attenuated by RGT treatment. In conclusion, RGT treatment decreases blood pressure and is effective in preventing the progression of renal injury in DOCA-salt hypertension, the mechanisms of which are associated with anti-inflammatory and anti-fibrotic effects through reducing the overexpression of ET-1, ED-1, COX-2 and TGF-beta1 in the kidney.

Rosiglitazone Ameliorates Endotoxin-Induced Organ Damage in Conscious Rats

Rosiglitazone is a peroxisome proliferator-activated receptor (PPAR)-γ agonist. By inhibiting nuclear factor κB (NF-κB), it decreases tumor necrosis factor-α (TNF-α) and interleukin 6 (IL-6) and has an anti-inflammatory effect. Endotoxin shock can induce the production of several inflammatory mediators such as TNF-α and IL-6, leading to multiple organ dysfunction and death. We investigated the effects of rosiglitazone (.3 mg/kg, intravenous administration) on the physiologic attributes and cytokine levels in endotoxin shock in conscious rats. Endotoxin shock was induced by intravenous injection of Klebsiella pneumoniae lipopolysaccharides (LPSs; 10 mg/kg) in conscious rats. Mean arterial pressure (MAP) and heart rate (HR) were continuously monitored for 24 hr after LPS administration. Levels of biochemical and cytokine parameters, including glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), blood urea nitrogen (BUN), creatinine (Cre), lactic dehydrogenase (LDH), creatine phosphokinase (CPK), glucose, TNF-α, and IL-6 were measured at 0, 1, 3, 6, 12, and 24 hr after sepsis. Endotoxin shock significantly increased blood GOT, GPT, BUN, Cre, LDH, CPK, glucose, TNF-α, and IL-6 levels and HR, while also decreasing MAP. Rosiglitazone diminished the increase in HR, decreased the markers of organ injury (GOT, GPT, BUN, Cre, LDH, CPK, glucose) and inflammatory biomarkers (TNF-α, IL-6), and did not affect MAP after LPS. In conclusion, rosiglitazone ameliorated endotoxin shock-induced markers of organ injury and suppressed the release of TNF-α and IL-6 in conscious rats.

Activation of peroxisome proliferator-activated receptor-gamma potentiates pro-inflammatory cytokine production, and adrenal and somatotropic changes of weaned pigs after Escherichia coli lipopolysaccharide challenge

Our previous study demonstrated mRNA and protein expression of peroxisome proliferator-activated receptor-g (PPAR-g) in the immune system of weaned pigs. In this report, to test the hypothesis that activation of PPAR-g in immune system modulates inflammatory response, and adrenal and somatotropic responses associated with immune challenge, we administered intraperitoneally PPAR-g agonist and/or antagonist in weaned pigs subjected to Escherichia coli lipopolysaccharide (LPS) challenge. Unexpectedly, we found that a single injection of the PPAR-g agonist rosiglitazone (given at 3 mg/kg body weight 30 min before LPS injection) failed to block pro-inflammatory cytokine production induced by LPS injection. Rather, plasma levels of tumor necrosis factor-a (TNF-a) and interleukin-6 (IL-6), mRNA abundance of TNF-a in thymus, spleen, mesenteric lymph node and peripheral white blood cells, mRNA abundance of IL-6 in thymus, protein levels of TNF-a in spleen and mesenteric lymph node, and protein levels of IL-6 in spleen and mesenteric lymph node, were elevated beyond the levels in control pigs injected with LPS. Furthermore, rosiglitazone potentiated the increase of plasma cortisol and prostaglandin E(2) concentrations, and the decrease of plasma insulin-like growth factor-1 concentration induced by LPS injection. Co-administration of the PPAR-g antagonist bisphenol A diglycidyl ether (given 30 mg/kg body weight) 30 min prior to treatment with rosiglitazone antagonized the effect of the PPAR-g agonist, indicating a PPAR-g-dependent effect. Our data indicate that ligand-induced activation of PPAR-g does not ameliorate but enhances pro-inflammatory cytokine production, and further potentiates the adrenal and somatotropic changes in weaned pigs subjected to E. coli LPS challenge, which suggests that PPAR-g activation may not be useful, but potentially harmful, in the treatment of immune challenge in livestock. Our results raise doubts about the prevalently accepted anti-inflammatory role for PPAR-g activation.

Up-regulated expression of peroxisome proliferator-activated receptor gamma in the hypothalamic-pituitary-adrenal axis of weaned pigs after Escherichia coli lipopolysaccharide challenge

The expression of peroxisome proliferator-activated receptor gamma (PPARgamma) was investigated in the hypothalamic-pituitary-adrenal (HPA) axis of weaned pigs after injection with 100 microg/kg bodyweight Escherichia coli lipopolysaccharide (LPS) (n=6) and control pigs injected with sterile saline (n=6). LPS increased PPARgamma mRNA and protein expression in the hypothalamus (23.8 and 3.1-fold relative to controls, respectively), pituitary gland (9.2 and 2.0-fold, respectively) and adrenal gland (3.5 and 2.3-fold, respectively) (P<0.05). LPS also induced an increase in PPARgamma immunohistochemical staining in the hypothalamus (1.3-fold), adenohypophysis (1.3-fold), adrenal cortex (1.4-fold) and adrenal medulla (1.6-fold) (P<0.05). Concurrent with up-regulated expression of PPARgamma, LPS increased the concentrations of plasma corticotrophin-releasing hormone (2.1-fold) and adrenocorticotrophin (1.4-fold) (P<0.05). LPS also induced elevations of interleukin 6 and tumour necrosis factor alpha mRNA levels in the hypothalamus (4.0 and 3.2-fold, respectively), pituitary gland (20.7 and 5.1-fold, respectively) and adrenal gland (3.9 and 3.3-fold, respectively) (P<0.05). PPARgamma may play a role in the regulation of neuroendocrine responses associated with immunological stress in pigs.

Rosiglitazone protects diabetic rats against kidney disease through the suppression of renal moncyte chemoattractant protein-1 expression

Although the pathogenetic mechanisms of diabetic nephropathy (DN) have not been elucidated thoroughly, an inflammatory mechanism has been suggested to contribute to its development and progression. Moncyte chemoattractant protein (MCP)-1 is a chemokine that can attract macrophages and T cells from the circulation to the local kidney, then activate them, and ultimately injure the renal tissue. Recent studies have demonstrated that thiazolidinediones decrease urinary albumin (ALB) excretion, which may be partly related to its anti-inflammatory action. Therefore, the effects of rosiglitazone on renal inflammation and renal injury were investigated in streptozotocin (STZ)-induced diabetic rats in this study. We examined the urinary excretion rates of ALB, retinal-binding protein (RBP), and MCP-1 of normal control group (Group C, n=8), STZ-induced diabetes mellitus group (Group D, n=8), and diabetes plus rosiglitazone (5 mg x kg-1 x day-1) treatment group (Group R, n=8) at the eighth week. The renal tissues of diabetic rats were obtained for reverse transcriptase-polymerase chain reaction to examine the expression of MCP-1 mRNA. Our results showed that compared to normal control, urinary excretion rates of ALB, RBP, and MCP-1 were significantly increased in untreated diabetic rats at the eighth week. However, rosiglitazone treatment could markedly decrease all the parameters above. In addition, urinary excretion rate of MCP-1 showed positive correlations with urinary ALB excretion, urinary RBP excretion, and kidney/body weight. The expressions of MCP-1 mRNA in renal tissues were markedly up-regulated in untreated diabetic rats, and these could be notably reduced by rosiglitazone treatment. In conclusion, rosiglitazone may have a potential therapeutic target in DN, which may be partly attributed to lowering of the expression of MCP-1 in the local kidney and the urinary excretion of MCP-1.

PPAR-gamma agonist attenuates renal interstitial fibrosis and inflammation through reduction of TGF-beta

Thiazolidinediones (TZDs), synthetic peroxisome proliferator-activated receptor (PPAR)-gamma ligands, have a central role in insulin sensitization and adipogenesis. It has been reported that TZDs exert protective effects in both diabetic and nondiabetic models of renal disease, although the exact mechanism is not well understood. In particular, only a few studies have reported the renoprotective effects of TZDs in nondiabetic models of tubulointerstitial fibrosis and inflammation. Therefore, we investigated the anti-fibrotic and anti-inflammatory effects of the TZD troglitazone in the mouse model of unilateral ureteral obstruction (UUO). C57BL/6J mice underwent UUO and were studied after 3 and 7 days. Animals were divided into three groups and received control vehicle, troglitazone (150 mg/kg per day) or troglitazone (300 mg/kg per day) by gavage. Kidneys were harvested for morphological, mRNA and protein analysis. Reverse-transcriptase-PCR was used to assess the expression of transforming growth factor-beta1 (TGF-beta1) and the TGF-beta1 type I receptor (TGF beta R-I). Protein expression was assessed by western blotting (TGF beta R-I) and immunostaining (TGF beta R-I, alpha-smooth muscle actin (alpha-SMA), type I collagen (collagen I), F4/80, and proliferating cell nuclear antigen (PCNA)). The expression of alpha-SMA, collagen I, and F4/80 was decreased in mice treated with troglitazone compared with the control group. The numbers of PCNA-positive interstitial cells were decreased in mice treated with troglitazone. TGF-beta1 mRNA and TGF beta R-I mRNA and protein expression were decreased in the group treated with troglitazone compared with the control group. The beneficial effects of troglitazone treatment were also dose dependent. PPAR-gamma agonist significantly reduced TGF-beta and attenuated renal interstitial fibrosis and inflammation in the model of UUO.

Renoprotective effect of rosiglitazone through the suppression of renal intercellular adhesion molecule-1 expression in streptozotocin-induced diabetic rats

OBJECTIVE

To observe the effect of rosiglitazone on serum intercellular adhesion molecule-1 (SICAM-1) level, urinary excretion of ICAM-1, and renal expression of ICAM-1, and investigate its possible renoprotective mechanisms in diabetic rats.

METHOD

Twenty-four Wistar Rats were divided into 3 groups: non-diabetic control rats (group A, no.=8), streptozotocin-induced diabetic rats (group B, no.=8), and diabetic rats treated with rosiglitazone (group C, no.=8). Rats in group C were treated with rosiglitazone (5 mg x kg(-1) x d(-1)) 1 week after the establishment of diabetic model, group A and B were treated with corresponding sodium chloride. Peripheral blood glucose was tested weekly. Glycosylated hemoglobin (HbA1c) and SICAM-1 as well as urinary albumin excretion rate (UAER), urinary retinol binding-protein (URBP) excretion rate, and urinary ICAM-1 (UICAM- 1) excretion rate were tested at the 8th week, and the renal tissues of all rats were obtained for evaluating kidney/body weight ratio, observing pathologic change via electron microscope, and for examining the expression of ICAM-1 mRNA by reverse transcriptase-PCR.

RESULTS

At the 8th week, the blood glucose, HbA1c levels, UAER, URBP excretion rate, kidney/body weight ratio and serum, urinary ICAM-1 levels all increased significantly in group B and group C in comparison with group A; however, the above-mentioned parameters in group C (except the blood glucose and HbA1c levels) were much lower than those in group B. In addition, both SICAM-1 and UICAM-1 were highly correlated with the UAER, URBP level, and kidney/body weight ratio in all rats; renal pathological lesions observed by electron microscope in group C were much lighter than those of group B; compared with group A, the expression of ICAM-1 mRNA was markedly up-regulated in group B and group C, and rosiglitazone was able to decrease the expression of ICAM-1 mRNA in the renal tissue.

CONCLUSION

Rosiglitazone could definitely protect against the renal injury of diabetic rats, which may be partly associated with decreasing the expression of ICAM-1 in the renal tissue, reducing ICAM-1 productions in both serum and urine.

Sepsis: links between pathogen sensing and organ damage

The host's inflammatory response to sepsis can be divided into two phases, the initial detection and response to the pathogen initiated by the innate immune response, and the persistent inflammatory state characterized by multiple organ dysfunction syndrome (MODS). New therapies aimed at pathogen recognition receptors (PRRs) particularly the TLRs and the NOD-like receptors offer hope to suppress the initial inflammatory response in early sepsis and to bolster this response in late sepsis. The persistence of MODS after the initial inflammatory surge can also be a determining factor to host survival. MODS is due to the cellular damage and death induced by sepsis. The mechanism of this cell death depends in part upon mitochondrial dysfunction. Damaged mitochondria have increased membrane permeability prompting their autophagic removal if few mitochondria are involved but apoptotic cell death may occur if the mitochondrial losses are more extensive. In addition. severe loss of mitochondria results in low cell energy stores, necrotic cell death, and increased inflammation driven by the release of cell components such as HMGB1. Therapies, which aim at improving cellular energy reserves such as the promotion of mitochondrial biogenesis by insulin, may have a role in future sepsis therapies. Finally, both the inflammatory responses and the susceptibility to organ failure may be modulated by nutritional status and micronutrients, such as zinc, Therapies aimed at micronutrient repletion may further augment approaches targeting PRR function and mitochondrial viability.

Genistein protects the kidney from cisplatin-induced injury

Oxidative stress and inflammation contribute to the pathogenesis of cisplatin-induced nephrotoxicity. We found that genistein, a tyrosine kinase inhibitor with broad specificities, and which also has estrogen-like activity, had protective effects on cisplatin-induced renal injury in mice. Genistein significantly decreased reactive oxygen species production, the expression of intercellular adhesion molecule-1 and monocyte chemoattractant protein-1 proteins, as well as the translocation of the p65 subunit of nuclear factor-kappaB into the nucleus and the infiltration of macrophages, all of which were increased in the kidney by cisplatin treatment. Genistein also decreased cisplatin-induced apoptosis by regulating p53 induction in kidney. Genistein significantly reduced reactive oxygen species production in cisplatin-treated normal human kidney HK-2 cells. These studies show that genistein or similar compounds might be useful in prevention of cisplatin-induced renal injury.

BMP-7 protects mesangial cells from injury by polymeric IgA

Bone morphogenetic protein-7 (BMP-7) is a potential therapeutic agent for acute and chronic renal diseases. Here we found that addition of polymeric IgA, isolated from patients with IgA nephropathy, increased the synthesis of tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), transforming growth factor-beta (TGF-beta) and fibronectin in cultured human mesangial cells, effects blunted by BMP-7. When mesangial cells were cultured with both polymeric IgA and BMP-7 there was an increase in the expression of peroxisome proliferator-activated receptor-gamma (PPAR-gamma). The activation of NF kappaB and TNF-alpha synthesis induced by polymeric IgA or TNF-alpha were downregulated by BMP-7 or rosiglitazone. BMP-7 inhibited TNF-alpha release from polymeric IgA-stimulated mesangial cells by activation of PPAR-gamma but suppressed TGF-beta release by mechanisms independent of PPAR-gamma. The expression of inhibitory Smad6 and 7 was increased whereas the expression of active Smad2 and 3 was reduced in these mesangial cells by BMP-7. Our study shows that BMP-7 ameliorates IgA nephropathy-derived polymeric IgA-induced TNF-alpha and TGF-beta synthesis in human mesangial cells through multiple mechanisms involving inhibitory Smads and PPAR-gamma.

Pioglitazone attenuates diabetic nephropathy through an anti-inflammatory mechanism in type 2 diabetic rats

BACKGROUND

Peroxisome proliferator-activated receptors (PPARs) are nuclear transcription factors that play a role in insulin sensitivity, lipid metabolism and inflammation. However, the effects of PPARgamma agonist on renal inflammation have not been fully examined in type 2 diabetic nephropathy.

METHODS

In the present study, we investigated the effect and molecular mechanism of the PPARgamma agonist, pioglitazone, on the progression of diabetic nephropathy in type 2 diabetic rats. Inflammatory markers including NF-kappaB, MCP-1 and pro-fibrotic cytokines were determined by RT-PCR, western blot, immunohistochemical staining and EMSA. In addition, to evaluate the direct anti-inflammatory effect of PPARgamma agonist, we performed an in vitro study using mesangial cells.

RESULTS

Treatment of OLETF rats with pioglitazone improved insulin sensitivity and kidney/body weight, but had a little effect on blood pressure. Pioglitazone treatment markedly reduced urinary albumin and MCP-1 excretion, and ameliorated glomerulosclerosis. In cDNA microarray analysis using renal cortical tissues, several inflammatory and profibrotic genes were significantly down-regulated by pioglitazone including NF-kappaB, CCL2, TGFbeta1, PAI-1 and VEGF. In renal tissues, pioglitazone treatment significantly reduced macrophage infiltration and NF-kappaB activation in association with a decrease in type IV collagen, PAI-1, and TGFbeta1 expression. In cultured mesangial cells, pioglitazone-activated endogenous PPARgamma transcriptional activity and abolished high glucose-induced collagen production. In addition, pioglitazone treatment also markedly suppressed high glucose-induced MCP-1 synthesis and NF-kappaB activation.

CONCLUSIONS

These data suggest that pioglitazone not only improves insulin resistance, glycaemic control and lipid profile, but also ameliorates renal injury through an anti-inflammatory mechanism in type 2 diabetic rats.

Increased expression of the peroxisome proliferator-activated receptor gamma in the immune system of weaned pigs after Escherichia coli lipopolysaccharide injection

Peroxisome proliferator-activated receptor gamma (PPARgamma), a member of the nuclear hormone receptor superfamily, has been implicated in regulation of immunity and inflammation in rodents and humans. The objective of the current study was to investigate whether the expression of PPARgamma was altered in the immune system of weaned pigs after Escherichia coli lipopolysaccharide (LPS) injection. PPARgamma expression was investigated in the thymus, spleen, mesenteric lymph node and peripheral white blood cells of weaned pigs (8.54+/-0.24 kg BW) after LPS injection (100 microg/kg BW, n=6) and controls (sterile saline, n=6), by using real-time polymerase chain reaction, Western blot analysis, and immunohistochemistry. Plasma pro-inflammatory cytokines and hormones were also assessed. LPS triggered PPARgamma mRNA and protein expression in the thymus (P<0.05, 4.24-fold; P<0.10, 1.46-fold), spleen (P<0.10, 2.75-fold; P<0.05, 1.84-fold), mesenteric lymph node (P<0.05, 4.32-fold; P<0.05, 1.96-fold) and peripheral white blood cells (P<0.001, 24.44-fold; P<0.001, 1.58-fold). The LPS-injected pigs showed an increase in PPARgamma staining in splenic corpuscle and periarterial lymphatic sheath of white pulp (P<0.05) and red pulp (P<0.001) of spleen, and in medullas of thymus lobule of thymus (P<0.05), and in thymus-dependent area of mesenteric lymph node (P<0.05) compared to the control pigs. Concurrent with up-regulation of PPARgamma expression, LPS induced increases in plasma interleukin-6 (P<0.001), tumor necrosis factor-alpha (P<0.001), cortisol (P<0.001), prostaglandin E(2) (P<0.01) and 15-deoxy-Delta(12,14)-prostaglandin J(2) (15 d-PGJ(2)) (P<0.05), and decreases in plasma insulin (P<0.10) and insulin-like growth factor-1 (P<0.001). These results suggest that induction of PPARgamma expression in immune system may be associated with the release of the natural PPARgamma activating ligand 15 d-PGJ(2), and play an important role in host response to immunological stress. Additionally, it is possible that PPARgamma would be a new therapeutic target in treatment of immunological stress of livestock.

Peroxisome proliferator-activated receptor-gamma agonists as potential anti-inflammatory agents in asthma and chronic obstructive pulmonary disease

Inhaled corticosteroids are the most effective therapy for chronic persistent asthma and have a role in the treatment of chronic obstructive pulmonary disease (COPD). However, corticosteroids have reduced efficacy in some patients with asthma and fail to halt the progressive deterioration in lung function characteristic of COPD. Additional or alternative drug treatments to corticosteroids are required to improve control of inflammation in patients with therapy resistant airway disease. Peroxisome proliferator-activated receptor-gamma (PPAR-gamma) agonists have displayed potent anti-inflammatory properties in experimental models of asthma and other airway diseases and as a result have the potential to become an additional treatment for asthma and COPD. We review the evidence from these experimental models and their applicability to asthma and COPD and the requirements for future clinical and experimental research.

Effect of nutritional support on glucose control

PURPOSE OF REVIEW

There is evidence that maintaining a normal glycemia level in critically ill patients has beneficial effects on outcome. Strategies aimed at lowering glycemia are based on the understanding of mechanisms regulating glucose metabolism.

RECENT FINDINGS

Activation of AMP protein kinase in skeletal muscle and in the liver leads to a reduction in glucose production, a stimulation of glucose uptake, and a lowering of glycemia. These mechanisms appear to be activated during exercise, or by the endogenous adipokine adiponectin. Alterations in adiponectin concentrations during critical illness may thus play a role in the metabolic stress responses. In addition, AMP-activated protein kinase is the target for drugs (metformin, thazolidinediones), which may be of interest in the intensive care unit. Besides insulin, plasma glucose concentrations may be lowered by hypocaloric feeding, or by feeding 'diabetic' formula with low glucose content and supplemented with fructose. Whether such approaches lead to beneficial effects comparable to those observed with insulin remains to be established.

SUMMARY

Recent findings regarding the molecular mechanisms underlying glucose transport and metabolism are summarized, and potential strategies other than insulin are outlined which may contribute to lowering glycemia in critically ill patients.

Protection of the kidney by thiazolidinediones: An assessment from bench to bedside

The global epidemic of diabetes mellitus has led to a continuous increase in the prevalence of diabetic nephropathy over the past years. Thus, diabetic nephropathy is currently the number one cause of end-stage renal disease in the Western world. It represents a major public health problem for which more effective prevention and treatment strategies are needed. Thiazolidinediones (TZDs) are a class of agents that lower blood glucose through reduction of insulin resistance in patients with type 2 diabetes. Growing evidence support the concept that TZDs have several beneficial effects on the cardiovascular system beyond their effects on glycemic control. These benefits include: blood pressure lowering, triglyceride reduction, high-density lipoprotein-cholesterol elevation, and reduction in subclinical vascular inflammation. Moreover, data from several animal and human studies support the notion that TZDs reduce urine albumin excretion and may prevent development of renal injury. The relative lack of evidence, however, demonstrating the effects of TZDs on hard renal outcomes mandates the need for well-designed trials with this particular objective. This paper summarizes all the data from clinical and experimental studies relevant to a possible renoprotective effect of TZDs and discusses actions of these compounds that may contribute toward this effect.

Rosiglitazone ameliorates cisplatin-induced renal injury in mice

BACKGROUND

Inflammatory mechanisms may play an important role in the pathogenesis of cisplatin nephrotoxicity. Agonists of the peroxisome proliferator-activated receptor-gamma (PPARgamma), such as rosiglitazone, have been recently demonstrated to regulate inflammation by modulating the production of inflammatory mediators and adhesion molecules. The purpose of this study was to examine the protective effects of rosiglitazone on cisplatin nephrotoxicity and to explore the mechanism of its renoprotection.

METHODS

Mice were treated with cisplatin with or without pre-treatment with rosiglitazone. Renal functions, histological findings, aquaporin 2 (AQP2) and adhesion molecule expression, macrophage infiltration and tumour necrosis factor-alpha (TNF-alpha) levels were investigated. The effect of rosiglitazone on nuclear factor (NF)-kappaB activity and on viability was examined using cultured human kidney (HK-2) cells.

RESULTS

Rosiglitazone significantly decreased both the damage to renal function and histological pathology after cisplatin injection. Pre-treatment with rosiglitazone reduced the systemic levels of TNF-alpha and down-regulated adhesion molecule expression in addition to the infiltration of inflammatory cells after cisplatin administration. Rosiglitazone restored the decreased AQP2 expression after cisplatin treatment. Pre-treatment with rosiglitazone blocked the phosphorylation of the p65 subunit of NF-kappaB in cultured HK-2 cells. Rosiglitazone had a protective effect via a PPARgamma-dependent pathway in cisplatin-treated HK-2 cells.

CONCLUSION

These results showed that pre-treatment with rosiglitazone attenuates cisplatin-induced renal damage through the suppression of TNF-alpha overproduction and NF-kappaB activation.

Protective role of l-2-oxothiazolidine-4-carboxylic acid in cisplatin-induced renal injury

BACKGROUND

Oxidative stress and inflammation are implicated in the pathogenesis of cisplatin-induced nephrotoxicity. l-2-oxothiazolidine-4-carboxylic acid (OTC) is a cysteine prodrug, and increases cellular glutathione (GSH). OTC is converted to cysteine by the intracellular enzyme, oxoprolinase. To date, the protective role of OTC on cisplatin-induced renal injury has not been investigated. The purpose of the present study was to examine the protective effect of OTC on cisplatin-induced renal injury and to examine the mechanism of its protection.

METHODS

Mice were treated with cisplatin with or without administration of OTC. The generation of reactive oxygen species (ROS), expression of intercellular adhesion molecule (ICAM)-1 and monocyte chemoattractant protein (MCP)-1 were determined in the kidney using 2',7'-dichlorofluorescein diacetate, immunostaining or western blot analysis. Nuclear factor (NF)-kappaB activity, infiltration of F4/80-positive cells and apoptosis were also investigated in addition to renal function and histology using electrophoretic mobility shift assay, immunostaining, western blot analysis, uridine triphosphate (dUTP) nick-end labelling or periodic acid-Schiff staining. The effect of OTC on superoxide dismutase activity and GSH level in cisplatin-treated normal adult human kidney (HK-2) cells were measured using assay kits.

RESULTS

The administration of OTC resulted in a significant reduction of cisplatin-induced ROS production, the p65 subunit of NF-kappaB translocation into nucleus, expression of ICAM-1, caspase 3 activity, expression of MCP-1 and the infiltration of macrophages into renal tissue. OTC markedly ameliorated renal damage induced by cisplatin through antioxidant and anti-inflammatory effect.

CONCLUSIONS

These results suggest that OTC can be a potential therapeutic agent in cisplatin-induced renal injury through decreasing the ROS levels and activation of NF-kappaB.

Activation of tubular epithelial cells in diabetic nephropathy and the role of the peroxisome proliferator-activated receptor-gamma agonist

The effects of advanced glycation end products (AGE) in the form of glycated albumin (GA) on the proinflammatory phenotype of cultured renal proximal tubular epithelial cells (PTEC) and the therapeutic potential of the peroxisome proliferator-activated receptor-gamma (PPAR-gamma) agonist were studied. Human PTEC were exposed to medium alone or supplemented with albumin or GA with or without previous addition of rosiglitazone (0.1 to 0.5 microM). Exposure to GA (up to 0.5 mg/ml) but not the equivalent dose of neat albumin significantly upregulated both mRNA and protein expression of IL-8 and soluble intercellular adhesion molecule-1 (sICAM-1) in a dose- and time-dependent manner. Using immunohistochemistry, ICAM-1 signals were detected in the tubular epithelia and peritubular capillaries in association with AGE deposition and leukocyte infiltration, whereas IL-8 staining was localized in the tubular epithelia of human diabetic kidney biopsies. Also in a dose-dependent manner, GA (0.5 mg/ml) but not albumin caused nuclear translocation of NF-kappaB and activation of mitogen-activated protein kinase (MAPK) p44/p42 and signal transducer and activator of transcription (STAT-1). Inhibition of these pathways with pyrrolidine dithiocarbamate, PD 98059, and fludarabine, respectively, attenuated GA-induced IL-8 secretion. Rosiglitazone dose-dependently attenuated GA-induced IL-8 and ICAM-1 signals in PTEC and completely abolished GA-induced STAT-1 signals but had no effect on NF-kappaB and MAPK activation. These findings suggest that AGE stimulate renal tubular expression of adhesion molecule and chemokine that together may account for the transmigration of inflammatory cells into the interstitial space during diabetic tubulopathy. Such proinflammatory phenotype may be partially modified by PPAR-gamma ligation through STAT-1 inhibition independent of NF-kappaB transcriptional activity and MAPK signaling.

Peroxisome proliferator-activated receptors and inflammation

Peroxisome proliferator-activated receptors (PPARs) are members of the nuclear hormone receptors family. PPARs are a family of 3 ligand-activated transcription factors: PPARalpha (NR1C1), PPARbeta/delta (NUC1; NR1C2), and PPARgamma (NR1C3). PPARalpha, -beta/delta, and -gamma are encoded by different genes but show substantial amino acid similarity, especially within the DNA and ligand binding domains. All PPARs act as heterodimers with the 9-cis-retinoic acid receptors (retinoid X receptor; RXRs) and play important roles in the regulation of metabolic pathways, including those of lipid of biosynthesis and glucose metabolism, as well as in a variety of cell differentiation, proliferation, and apoptosis pathways. Recently, there has been a great deal of interest in the involvement of PPARs in inflammatory processes. PPAR ligands, in particular those of PPARalpha and PPARgamma, inhibit the activation of inflammatory gene expression and can negatively interfere with pro-inflammatory transcription factor signaling pathways in vascular and inflammatory cells. Furthermore, PPAR levels are differentially regulated in a variety of inflammatory disorders in man, where ligands appear to be promising new therapies.