Metformin exerts antitumor activity via induction of multiple death pathways in tumor cells and activation of a protective immune response.

The antitumor effect of metformin has been demonstrated in several types of cancer; however, the mechanisms involved are incompletely understood. In this study, we showed that metformin acts directly on melanoma cells as well as on the tumor microenvironment, particularly in the context of the immune response. In vitro, metformin induces a complex interplay between apoptosis and autophagy in melanoma cells. The anti-metastatic activity of metformin in vivo was assessed in several mouse models challenged with B16F10 cells. Metformin's activity was, in part, immune system-dependent, whereas its antitumor properties were abrogated in immunodeficient (NSG) mice. Metformin treatment increased the number of lung CD8-effector-memory T and CD4+Foxp3+IL-10+ T cells in B16F10-transplanted mice. It also decreased the levels of Gr-1+CD11b+ and RORγ+ IL17+CD4+ cells in B16F10-injected mice and the anti-metastatic effect was impaired in RAG-1-/- mice challenged with B16F10 cells, suggesting an important role for T cells in the protection induced by metformin. Finally, metformin in combination with the clinical metabolic agents rapamycin and sitagliptin showed a higher antitumor effect. The metformin/sitagliptin combination was effective in a BRAFV600E/PTEN tamoxifen-inducible murine melanoma model. Taken together, these results suggest that metformin has a pronounced effect on melanoma cells, including the induction of a strong protective immune response in the tumor microenvironment, leading to tumor growth control, and the combination with other metabolic agents may increase this effect.

Protective role of NKT cells and macrophage M2-driven phenotype in bleomycin-induced pulmonary fibrosis.

Pulmonary fibrosis is a result of an abnormal wound healing in lung tissue triggered by an excessive accumulation of extracellular matrix proteins, loss of tissue elasticity, and debit of ventilatory function. NKT cells are a major source of Th1 and Th2 cytokines and may be crucial in the polarization of M1/M2 macrophages in pulmonary fibrogenesis. Although there appears to be constant scientific progress in that field, pulmonary fibrosis still exhibits no current cure. From these facts, we hypothesized that NKT cells could influence the development of pulmonary fibrosis via modulation of macrophage activation. Wild type (WT) and NKT type I cell-deficient mice (Jα18-/-) were subjected to the protocol of bleomycin-induced pulmonary fibrosis with or without treatment with NKT cell agonists α-galactosylceramide and sulfatide. The participation of different cell populations, collagen deposition, and protein levels of different cytokines involved in inflammation and fibrosis was evaluated. The results indicate a benign role of NKT cells in Jα18-/- mice and in wild-type α-galactosylceramide-sulfatide-treated groups. These animals presented lower levels of collagen deposition, fibrogenic molecules such as TGF-ß and vimentin and improved survival rates. In contrast, WT mice developed a Th2-driven response augmenting IL-4, 5, and 13 protein synthesis and increased collagen deposition. Furthermore, the arginase-1 metabolic pathway was downregulated in wild-type NKT-activated and knockout mice indicating lower activity of M2 macrophages in lung tissue. Hence, our data suggest that NKT cells play a protective role in this experimental model by down modulating the Th2 milieu, inhibiting M2 polarization and finally preventing fibrosis.

CCR2 contributes to the recruitment of monocytes and leads to kidney inflammation and fibrosis development.

Chemokines are a large family of proteins that, once associated to its receptor on leukocytes, stimulate their movement and migration from blood to tissues. Once in the tissue, immune cells trigger inflammation that, when uncontrolled, leads to fibrosis development. Among the immune cells, macrophages take a special role in fibrosis formation, since macrophage depletion reflects less collagen deposition. The majority of tissue macrophages is derived from monocytes, especially monocytes expressing the chemokine receptor CCR2. Here, we investigated the role of infiltrating CCR2+ cells in the development of fibrosis, and specifically, the dynamic of infiltration of these cells into kidneys under chronic obstructive lesion. Using liposome-encapsulated clodronate, we observed that macrophage depletion culminated in less collagen deposition and reduced chemokines milieu that were released in the damaged kidney after obstructive nephropathy. We also obstructed the kidneys of CCL3-/-, CCR2-/-, CCR4-/-, CCR5-/-, and C57BL/6 mice and we found that among all animals, CCR2-/- mice demonstrated the more robust protection, reflected by less inflammatory and Th17-related cytokines and less collagen formation. Next we evaluated the dynamic of CCR2+/rfp cell infiltration and we observed that they adhere onto the vessels at early stages of disease, culminating in increased recruitment of CCR2+/rfp cells at later stages. On the other hand, CCR2rfp/rfp animals exhibited less fibrosis formation and reduced numbers of recruited cells at later stages. We have experimentally demonstrated that inflammatory CCR2+ cells that reach the injured kidney at initial stages after tissue damage are responsible for the fibrotic pattern observed at later time points in the context of UUO.

Soluble Uric Acid Activates the NLRP3 Inflammasome.

Uric acid is a damage-associated molecular pattern (DAMP), released from ischemic tissues and dying cells which, when crystalized, is able to activate the NLRP3 inflammasome. Soluble uric acid (sUA) is found in high concentrations in the serum of great apes, and even higher in some diseases, before the appearance of crystals. In the present study, we sought to investigate whether uric acid, in the soluble form, could also activate the NLRP3 inflammasome and induce the production of IL-1ß. We monitored ROS, mitochondrial area and respiratory parameters from macrophages following sUA stimulus. We observed that sUA is released in a hypoxic environment and is able to induce IL-1ß release. This process is followed by production of mitochondrial ROS, ASC speck formation and caspase-1 activation. Nlrp3-/- macrophages presented a protected redox state, increased maximum and reserve oxygen consumption ratio (OCR) and higher VDAC protein levels when compared to WT and Myd88-/- cells. Using a disease model characterized by increased sUA levels, we observed a correlation between sUA, inflammasome activation and fibrosis. These findings suggest sUA activates the NLRP3 inflammasome. We propose that future therapeutic strategies for renal fibrosis should include strategies that block sUA or inhibit its recognition by phagocytes.

Administration of α-Galactosylceramide Improves Adenine-Induced Renal Injury.

Natural killer T (NKT) cells are a subset of lymphocytes that reacts to glycolipids presented by CD1d. Invariant NKT cells (iNKT) correspond to >90% of the total population of NKTs and reacts to α-galactosylceramide (αGalCer). αGalCer promotes a complex mixture of Th1 and Th2 cytokines, as interferon (IFN)-γ and interleukin (IL)-4. NKT cells and IFN-γ are known to participate in some models of renal diseases, but further studies are still necessary to elucidate their mechanisms. The aim of our study was to analyze the participation of iNKT cells in an experimental model of tubule-interstitial nephritis. We used 8-wk-old C57BL/6j, Jα18KO and IFN-γKO mice. They were fed a 0.25% adenine diet for 10 d. Both adenine-fed wild-type (WT) and Jα18KO mice exhibited renal dysfunction, but adenine-fed Jα18KO mice presented higher expression of kidney injury molecule-1 (KIM-1), tumor necrosis factor (TNF)-α and type I collagen. To analyze the role of activated iNKT cells in our model, we administered αGalCer in WT mice during adenine ingestion. After αGalCer injection, we observed a significant reduction in serum creatinine, proinflammatory cytokines and renal fibrosis. However, this improvement in renal function was not observed in IFN-γKO mice after αGalCer treatment and adenine feeding, illustrating that this cytokine plays a role in our model. Our findings may suggest that IFN-γ production is one of the factors contributing to improved renal function after αGalCer administration.

Formaldehyde inhalation during pregnancy abolishes the development of acute innate inflammation in offspring.

Formaldehyde (FA) is an environmental and occupational pollutant that induces programming mechanisms on the acquired immune host defense in offspring when exposed during the prenatal period. Hence, here we investigated whether the exposure of FA on pregnant rats could affect the development of an innate acute lung injury in offspring induced by lipopolissacaride (LPS) injection. Pregnant Wistar rats were exposed to FA (0.92 mg/m(3)) or vehicle (distillated water), both 1 h/day, 5 days/week, from 1 to 21 days of pregnancy. Non-manipulated rats were used as control. After 30 days of birth, the offspring was submitted to injection of LPS (Salmonella abortus equi, 5 mg/kg, i.p.). Systemic and lung inflammatory parameters were evaluated 24 h later. Exposure to FA during gestation abolished the development of acute lung injury in offspring, as observed by reduced number of leukocytes in the bronchoalveolar fluid (BAL), in the blood and in the bone marrow, and decreased myeloperoxidase activity in the lung. Moreover, phagocytes from BAL presented normal phagocytosis, but reduced oxidative burst. Alterations on the profile of inflammatory cytokines were evidenced by reduced mRNA levels of IL-6 and elevated levels of IL-10 and IFN gamma in the lung tissue. Indeed, mRNA levels of toll-likereceptor-4 and nuclear factor-kappa B translocation into the nucleus were also reduced. Additionally, hyperresponsiveness to methacholine was blunted in the trachea of offspring of FA exposed mothers. Together, our data clearly show that FA exposure in the prenatal period modifies the programming mechanisms of the innate defense in the offspring leading to impaired defense against infections.

Macrophage trafficking as key mediator of adenine-induced kidney injury.

Macrophages play a special role in the onset of several diseases, including acute and chronic kidney injuries. In this sense, tubule interstitial nephritis (TIN) represents an underestimated insult, which can be triggered by different stimuli and, in the absence of a proper regulation, can lead to fibrosis deposition. Based on this perception, we evaluated the participation of macrophage recruitment in the development of TIN. Initially, we provided adenine-enriched food to WT and searched for macrophage presence and action in the kidney. Also, a group of animals were depleted of macrophages with the clodronate liposome while receiving adenine-enriched diet. We collected blood and renal tissue from these animals and renal function, inflammation, and fibrosis were evaluated. We observed higher expression of chemokines in the kidneys of adenine-fed mice and a substantial protection when macrophages were depleted. Then, we specifically investigated the role of some key chemokines, CCR5 and CCL3, in this TIN experimental model. Interestingly, CCR5 KO and CCL3 KO animals showed less renal dysfunction and a decreased proinflammatory profile. Furthermore, in those animals, there was less profibrotic signaling. In conclusion, we can suggest that macrophage infiltration is important for the onset of renal injury in the adenine-induced TIN.

Exposure to low doses of formaldehyde during pregnancy suppresses the development of allergic lung inflammation in offspring.

Formaldehyde (FA) is an environmental and occupational pollutant, and its toxic effects on the immune system have been shown. Nevertheless, no data are available regarding the programming mechanisms after FA exposure and its repercussions for the immune systems of offspring. In this study, our objective was to investigate the effects of low-dose exposure of FA on pregnant rats and its repercussion for the development of allergic lung inflammation in offspring. Pregnant Wistar rats were assigned in 3 groups: P (rats exposed to FA (0.75 ppm, 1 h/day, 5 days/week, for 21 days)), C (rats exposed to vehicle of FA (distillated water)) and B (rats non-manipulated). After 30 days of age, the offspring was sensitised with ovalbumin (OVA)-alum and challenged with aerosolized OVA (1%, 15 min, 3 days). After 24 h the OVA challenge the parameters were evaluated. Our data showed that low-dose exposure to FA during pregnancy induced low birth weight and suppressed the development of allergic lung inflammation and tracheal hyperresponsiveness in offspring by mechanisms mediated by reduced anaphylactic antibodies synthesis, IL-6 and TNF-alpha secretion. Elevated levels of IL-10 were found. Any systemic alteration was detected in the exposed pregnant rats, although oxidative stress in the uterine environment was evident at the moment of the delivery based on elevated COX-1 expression and reduced cNOS and SOD-2 in the uterus. Therefore, we show the putative programming mechanisms induced by FA on the immune system for the first time and the mechanisms involved may be related to oxidative stress in the foetal microenvironment.

Leptin downregulates LPS-induced lung injury: role of corticosterone and insulin.

BACKGROUND/AIMS: We investigated the effects of leptin in the development of lipopolysaccharide (LPS)-induced acute lung inflammation (ALI) in lean mice. METHODS: Mice were administered leptin (1.0µg/g) or leptin (1.0µg/g) followed by LPS (1.5µg/g) intranasally. Additionally, some animals were given LPS (1.5µg/g) or saline intranasally alone, as a control. Tissue samples and fluids were collected six hours after instillation. RESULTS: We demonstrated that leptin alone did not induce any injury. Local LPS exposure resulted in significant acute lung inflammation, characterized by a substantial increase in total cells, mainly neutrophils, in bronchoalveolar lavages (BAL). We also observed a significant lymphocyte influx into the lungs associated with enhanced lung expression of chemokines and cytokines (KC, RANTES, TNF-α, IFN-γ, GM-CSF and VEGF). LPS-induced ALI was characterized by the enhanced expression of ICAM-1 and iNOS in the lungs. Mice that received LPS showed an increase in insulin levels. Leptin, when administered prior to LPS instillation, abolished all of these effects. LPS induced an increase in corticosterone levels, and leptin potentiated this event. CONCLUSION: These data suggest that exogenous leptin may promote protection during sepsis, and downregulation of the insulin levels and upregulation of corticosterone may be important mechanisms in the amelioration of LPS-induced ALI.

Activation of platelet-activating factor receptor exacerbates renal inflammation and promotes fibrosis.

Platelet-activating factor (PAF) is a lipid mediator with important pro-inflammatory effects, being synthesized by several cell types including kidney cells. Although there is evidence of its involvement in acute renal dysfunction, its role in progressive kidney injury is not completely known. In the present study, we investigated the role of PAF receptor (PAFR) in an experimental model of chronic renal disease. Wild-type (WT) and PAFR knockout (KO) mice underwent unilateral ureter obstruction (UUO), and at kill time, urine and kidney tissue was collected. PAFR KO animals compared with WT mice present: (a) less renal dysfunction, evaluated by urine protein/creatinine ratio; (b) less fibrosis evaluated by collagen deposition, type I collagen, Lysyl Oxidase-1 (LOX-1) and transforming growth factor ß (TGF-ß) gene expression, and higher expression of bone morphogenetic protein 7 (BMP-7) (3.3-fold lower TGF-ß/BMP-7 ratio); (c) downregulation of extracellular matrix (ECM) and adhesion molecule-related machinery genes; and (d) lower levels of pro-inflammatory cytokines. These indicate that PAFR engagement by PAF or PAF-like molecules generated during UUO potentiates renal dysfunction and fibrosis and might promote epithelial-to-mesenchymal transition (EMT). Also, early blockade of PAFR after UUO leads to a protective effect, with less fibrosis deposition. In conclusion, PAFR signaling contributes to a pro-inflammatory environment in the model of obstructive nephropathy, favoring the fibrotic process, which lately will generate renal dysfunction and progressive organ failure.

Acute kidney injury reduces phagocytic and microbicidal capacities of alveolar macrophages.

BACKGROUND/AIMS: Renal ischaemia-reperfusion injury (IRI) is a systemic inflammatory process in which Th1 responses predominate affecting other organs including the lungs. The present study explored the phagocytic and microbicidal capacity of macrophages in rats with lung inflammation that underwent IRI. METHODS: The alveolar macrophages of rats sensitised to OVA were evaluated for phagocytosis and bacterial killing 24h after antigen challenge in animals with or without prior submission to 60 min of renal ischaemia. RESULTS: Bronchoalveolar lavage had a high level of cellular infiltrate in immunised animals (420%) compared with control animals; IRI significantly reduced this infiltration (52%). Macrophages from animals immunised and challenged with OVA presented a 10x increase in phagocytic capacity compared to the control group, whereas immunised animals subjected to IRI showed a reduction in the phagocytic index of 68%. The killing of Klebsiella pneumoniae by macrophages from immunised animals was higher (56%) compared with the control group but reduced in animals submitted to IRI (45%). Immunised and challenged group showed an increase in gene expression levels of IL-10(450%), HO-1 (259%), INF-γ (460%) and MCP-1 (370%) compared to the immunised group subjected to IRI. CONCLUSIONS: Renal ischaemia and reperfusion injury apparently alters the phagocytic and microbicidal capacity of macrophages, reducing lung inflammation to OVA.

Transcriptome analysis of renal ischemia/reperfusion injury and its modulation by ischemic pre-conditioning or hemin treatment.

Ischemia/reperfusion injury (IRI) is a leading cause of acute renal failure. The definition of the molecular mechanisms involved in renal IRI and counter protection promoted by ischemic pre-conditioning (IPC) or Hemin treatment is an important milestone that needs to be accomplished in this research area. We examined, through an oligonucleotide microarray protocol, the renal differential transcriptome profiles of mice submitted to IRI, IPC and Hemin treatment. After identifying the profiles of differentially expressed genes observed for each comparison, we carried out functional enrichment analysis to reveal transcripts putatively involved in potential relevant biological processes and signaling pathways. The most relevant processes found in these comparisons were stress, apoptosis, cell differentiation, angiogenesis, focal adhesion, ECM-receptor interaction, ion transport, angiogenesis, mitosis and cell cycle, inflammatory response, olfactory transduction and regulation of actin cytoskeleton. In addition, the most important overrepresented pathways were MAPK, ErbB, JAK/STAT, Toll and Nod like receptors, Angiotensin II, Arachidonic acid metabolism, Wnt and coagulation cascade. Also, new insights were gained about the underlying protection mechanisms against renal IRI promoted by IPC and Hemin treatment. Venn diagram analysis allowed us to uncover common and exclusively differentially expressed genes between these two protective maneuvers, underscoring potential common and exclusive biological functions regulated in each case. In summary, IPC exclusively regulated the expression of genes belonging to stress, protein modification and apoptosis, highlighting the role of IPC in controlling exacerbated stress response. Treatment with the Hmox1 inducer Hemin, in turn, exclusively regulated the expression of genes associated with cell differentiation, metabolic pathways, cell cycle, mitosis, development, regulation of actin cytoskeleton and arachidonic acid metabolism, suggesting a pleiotropic effect for Hemin. These findings improve the biological understanding of how the kidney behaves after IRI. They also illustrate some possible underlying molecular mechanisms involved in kidney protection observed with IPC or Hemin treatment maneuvers.

Low-level laser therapy decreases renal interstitial fibrosis.

OBJECTIVE: the purpose of this study was to investigate the effect of low-level laser therapy (LLLT) on chronic kidney disease (CKD) in a model of unilateral ureteral obstruction (UUO). BACKGROUND DATA: Regardless of the etiology, CKD involves progressive widespread tissue fibrosis, tubular atrophy, and loss of kidney function. This process also occurs in kidney allograft. At present, effective therapies for this condition are lacking. We investigated the effects of LLLT on the interstitial fibrosis that occurs after experimental UUO in rats. METHODS: The occluded kidney of half of the 32 Wistar rats that underwent UUO received a single intraoperative dose of LLLT (AlGaAs laser, 780 nm, 22.5 J/cm(2), 30 mW, 0.75 W/cm(2), 30 sec on each of nine points). After 14 days, renal fibrosis was assessed by Sirius red staining under polarized light. Immunohistochemical analyses quantitated the renal tissue cells that expressed fibroblast (FSP-1) and myofibroblast (α-SMA) markers. Reverse transcriptase polymerase chain reaction (RT-PCR) was performed to determine the mRNA expression of interleukin (IL)-6, monocyte chemotactic protein-1 (MCP-1), transforming growth factor (TGF)-ß1 and Smad3. RESULTS: The UUO and LLLT animals had less fibrosis than the UUO animals, as well having decreased expression inflammatory and pro-fibrotic markers. CONCLUSIONS: For the first time, we showed that LLLT had a protective effect regarding renal interstitial fibrosis. It is conceivable that by attenuating inflammation, LLLT can prevent tubular activation and transdifferentiation, which are the two processes that mainly drive the renal fibrosis of the UUO model.

Oxidative stress and modification of renal vascular permeability are associated with acute kidney injury during P. berghei ANKA infection.

Malaria associated-acute kidney injury (AKI) is associated with 45% of mortality in adult patients hospitalized with severe form of the disease. However, the causes that lead to a framework of malaria-associated AKI are still poorly characterized. Some clinical studies speculate that oxidative stress products, a characteristic of Plasmodium infection, as well as proinflammatory response induced by the parasite are involved in its pathophysiology. Therefore, we aimed to investigate the development of malaria-associated AKI during infection by P. berghei ANKA, with special attention to the role played by the inflammatory response and the involvement of oxidative stress. For that, we took advantage of an experimental model of severe malaria that showed significant changes in the renal pathophysiology to investigate the role of malaria infection in the renal microvascular permeability and tissue injury. Therefore, BALB/c mice were infected with P. berghei ANKA. To assess renal function, creatinine, blood urea nitrogen, and ratio of proteinuria and creatininuria were evaluated. The products of oxidative stress, as well as cytokine profile were quantified in plasma and renal tissue. The change of renal microvascular permeability, tissue hypoxia and cellular apoptosis were also evaluated. Parasite infection resulted in renal dysfunction. Furthermore, we observed increased expression of adhesion molecule, proinflammatory cytokines and products of oxidative stress, associated with a decrease mRNA expression of HO-1 in kidney tissue of infected mice. The measurement of lipoprotein oxidizability also showed a significant increase in plasma of infected animals. Together, our findings support the idea that products of oxidative stress, as well as the immune response against the parasite are crucial to changes in kidney architecture and microvascular endothelial permeability of BALB/c mice infected with P. berghei ANKA.

MyD88 signaling pathway is involved in renal fibrosis by favoring a TH2 immune response and activating alternative M2 macrophages.

Inflammation contributes to the pathogenesis of chronic kidney disease (CKD). Molecules released by the inflamed injured tissue can activate toll-like receptors (TLRs), thereby modulating macrophage and CD4(+) T-cell activity. We propose that in renal fibrogenesis, M2 macrophages are recruited and activated in a T helper subset 2 cell (T(H)2)-prone inflammatory milieu in a MyD88-dependent manner. Mice submitted to unilateral ureteral ligation (UUO) demonstrated an increase in macrophage infiltration with collagen deposition after 7 d. Conversely, TLR2, TLR4 and MyD88 knockout (KO) mice had an improved renal function together with diminished T(H)2 cytokine production and decreased fibrosis formation. Moreover, TLR2, TLR4 and MyD88 KO animals exhibited less M2 macrophage infiltration, namely interleukin (IL)-10(+) and CD206(+) CD11b(high) cells, at 7 d after surgery. We evaluated the role of a T(H)2 cytokine in this context, and observed that the absence of IL-4 was associated with better renal function, decreased IL-13 and TGF-ß levels, reduced arginase activity and a decrease in fibrosis formation when compared with IL-12 KO and wild-type (WT) animals. Indeed, the better renal outcomes and the decreased fibrosis formation were restricted to the deficiency of IL-4 in the hematopoietic compartment. Finally, macrophage depletion, rather than the absence of T cells, led to reduced lesions of the glomerular filtration barrier and decreased collagen deposition. These results provide evidence that future therapeutic strategies against renal fibrosis should be accompanied by the modulation of the M1:M2 and T(H)1:T(H)2 balance, as T(H)2 and M2 cells are predictive of fibrosis toward mechanisms that are sensed by innate immune response and triggered in a MyD88-dependent pathway.

TLR2, TLR4 and the MYD88 signaling pathway are crucial for neutrophil migration in acute kidney injury induced by sepsis.

The aim of this study was to investigate the role of TLR2, TLR4 and MyD88 in sepsis-induced AKI. C57BL/6 TLR2(-/-), TLR4(-/-) and MyD88(-/-) male mice were subjected to sepsis by cecal ligation and puncture (CLP). Twenty four hours later, kidney tissue and blood samples were collected for analysis. The TLR2(-/-), TLR4(-/-) and MyD88(-/-) mice that were subjected to CLP had preserved renal morphology, and fewer areas of hypoxia and apoptosis compared with the wild-type C57BL/6 mice (WT). MyD88(-/-) mice were completely protected compared with the WT mice. We also observed reduced expression of proinflammatory cytokines in the kidneys of the knockout mice compared with those of the WT mice and subsequent inhibition of increased vascular permeability in the kidneys of the knockout mice. The WT mice had increased GR1(+low) cells migration compared with the knockout mice and decreased in GR1(+high) cells migration into the peritoneal cavity. The TLR2(-/-), TLR4(-/-), and MyD88(-/-) mice had lower neutrophil infiltration in the kidneys. Depletion of neutrophils in the WT mice led to protection of renal function and less inflammation in the kidneys of these mice. Innate immunity participates in polymicrobial sepsis-induced AKI, mainly through the MyD88 pathway, by leading to an increased migration of neutrophils to the kidney, increased production of proinflammatory cytokines, vascular permeability, hypoxia and apoptosis of tubular cells.

Inflammatory milieu as an early marker of kidney injury in offspring rats from diabetic mothers.

The present study investigated the early presence of inflammatory response in renal tissue of young offspring from diabetic mothers. The effect of L-arginine (L-arg) supplementation was also investigated. The offspring was divided into four groups: group CO (controls); group DO (diabetic offspring); group CA (CO receiving 2% L-arg solution) and group DA (DO receiving the 2% L-arg solution). Glycemia, arterial pressure and renal function were evaluated; gene and protein expression of pro-inflammatory cytokines were also measured. Blood pressure levels were significantly increased in 2 and 6 month-old DO rats, whereas L-arg administration caused a significant decrease in the DA group, at both ages. DO rats showed a significantly blunted glycemic response to exogenous insulin. In 2 month-old DO animals, renal protein expression of pro-inflammatory molecules was significantly increased. At six months of age, we also observed an increase in gene expression of pro-inflammatory molecules, whereas L-arg supplementation prevented this increase at both ages. Our data suggest that activation of inflammatory pathways is present early in the kidney of DO rats, and that L-arg can attenuate the expression of these markers of tissue inflammation. Our results also reinforce the concept that intrauterine environmental factors are a fundamental determinant in the development of metabolic and vascular diseases later in life.

Cytoprotection behind heme oxygenase-1 in renal diseases.

Renal insults are considered a public health problem and are linked to increased rates of morbidity and mortality worldwide. The heme oxygenase (HO) system consists of evolutionary specialized machinery that degrades free heme and produces carbon monoxide, biliverdin and free iron. In this sense, the inducible isoform HO-1 seems to develop an important role and is widely studied. The reaction involved with the HO-1 molecule provides protection to injured tissue, directly by reducing the toxic heme molecule and indirectly by the release of its byproducts. The up regulation of HO-1 enzyme has largely been described as providing antioxidant, antiapoptotic, anti-inflammatory and immunomodulatory properties. Several works have explored the importance of HO-1 in renal diseases and they have provided consistent evidence that its overexpression has beneficial effects in such injuries. So, in this review we will focus on the role of HO-1 in kidney insults, exploring the protective effects of its up regulation and the enhanced deleterious effects of its inhibition or gene deletion.

Pivotal role of Toll-like receptors 2 and 4, its adaptor molecule MyD88, and inflammasome complex in experimental tubule-interstitial nephritis.

Tubule-interstitial nephritis (TIN) results in decreased renal function and interstitial inflammation, which ultimately leads to fibrosis. Excessive adenine intake can cause TIN because xanthine dehydrogenase (XDH) can convert this purine into an insoluble compound, which precipitates in the tubuli. Innate immune sensors, such as Toll-like receptors (TLR) and inflammasome complex, play a crucial role in the initiation of inflammation. The aim of this study was to evaluate the roles of TLR-2 and -4, Myd88 and inflammasome complex in an experimental model of TIN. Here, we show that wild-type (WT) mice fed adenine-enriched food exhibited significant renal dysfunction and enhanced cellular infiltration accompanied by collagen deposition. They also presented higher gene and protein expression of pro-inflammatory cytokines. In contrast, TLR-2, -4, MyD88, ASC and Caspase-1 KO mice showed renoprotection associated with expression of inflammatory molecules at levels comparable to controls. Furthermore, treatment of WT animals with allopurinol, an XDH inhibitor, led to reduced levels of uric acid, oxidative stress, collagen deposition and a downregulation of the NF-kB signaling pathway. We concluded that MyD88 signaling and inflammasome participate in the development of TIN. Furthermore, inhibition of XDH seems to be a promising way to therapeutically target the developing inflammatory process.

Formaldehyde induces lung inflammation by an oxidant and antioxidant enzymes mediated mechanism in the lung tissue.

Formaldehyde (FA) is an indoor and outdoor pollutant widely used by many industries, and its exposure is associated with inflammation and oxidative stress in the airways. Our previous studies have demonstrated the role of reactive oxygen species (ROS) in lung inflammation induced by FA inhalation but did not identify source of the ROS. In the present study, we investigate the effects of FA on the activities and gene expression of glutathione peroxidase (GPX), glutathione reductase (GR), glutathione S-transferase (GST), superoxide dismutase (SOD) 1 and 2, catalase (CAT), nitric oxide synthase (iNOS and cNOS) and cyclooxygenase (COX) 1 and 2. The hypothesized link between NADPH-oxidase, nitric oxide synthase and cyclooxygenase, the lung inflammation after FA inhalation was also investigated. For experiments, male Wistar rats were submitted to FA inhalation (1%, 90 min daily) for 3 consecutive days. The treatments with apocynin and indomethacin before the FA exposure reduced the number of neutrophils recruited into the lung. Moreover, the treatments with apocynin and indomethacin blunted the effect of FA on the generation of IL-1ß, while the treatments with L-NAME and apocynin reduced the generation of IL-6 by lung explants when compared to the untreated group. FA inhalation increased the levels of NO and hydrogen peroxide by BAL cells cultured and the treatments with apocynin and l-NAME reduced these generations. FA inhalation did not modify the activities of GPX, GR, GST and CAT but reduced the activity of SOD when compared to the naïve group. Significant increases in SOD-1 and -2, CAT, iNOS, cNOS and COX-1 expression were observed in the FA group compared to the naïve group. The treatments with apocynin, indomethacin and L-NAME reduced the gene expression of antioxidant and oxidant enzymes. In conclusion, our results indicate that FA causes a disruption of the physiological balance between oxidant and antioxidant enzymes in lung tissue, most likely favoring the oxidant pathways and thus positively modulating lung inflammation.