Leptin as a link between the immune system and kidney-related diseases: leading actor or just a coadjuvant?

Food intake and nutritional status modify the physiological responses of the immune system to illness and infection and regulate the development of chronic inflammatory processes, such as kidney disease. Adipose tissue secretes immune-related proteins called adipokines that have pleiotropic effects on both the immune and neuroendocrine systems, linking metabolism and immune physiology. Leptin, an adipose tissue-derived adipokine, displays a variety of immune and physiological functions, and participates in several immune responses. Here, we review the current literature on the role of leptin in kidney diseases, linking adipose tissue and the immune system with kidney-related disorders. The modulation of this adipose hormone may have a major impact on the treatment of several immune- and metabolic-related kidney diseases.

Exercise and caloric restriction alter the immune system of mice submitted to a high-fat diet

As the size of adipocytes increases during obesity, the establishment of resident immune cells in adipose tissue becomes an important source of proinflammatory mediators. Exercise and caloric restriction are two important, nonpharmacological tools against body mass increase. To date, their effects on the immune cells of adipose tissue in obese organisms, specifically when a high-fat diet is consumed, have been poorly investigated. Thus, after consuming a high-fat diet, mice were submitted to chronic swimming training or a 30% caloric restriction in order to investigate the effects of both interventions on resident immune cells in adipose tissue. These strategies were able to reduce body mass and resulted in changes in the number of resident immune cells in the adipose tissue and levels of cytokines/chemokines in serum. While exercise increased the number of NK cells in adipose tissue and serum levels of IL-6 and RANTES, caloric restriction increased the CD4+/CD8+ cell ratio and MCP-1 levels. Together, these data demonstrated that exercise and caloric restriction modulate resident immune cells in adipose tissues differently in spite of an equivalent body weight reduction. Additionally, the results also reinforce the idea that a combination of both strategies is better than either individually for combating obesity

Immune receptors and adhesion molecules in human pulmonary leptospirosis

Pulmonary involvement in leptospirosis has been increasingly reported in the last 20 years, being related to the severity and mortality of the disease. The pathogenesis of pulmonary hemorrhage in leptospirosis is not understood. Lung endothelial cells have been proposed as targets in the pathogenesis of lung involvement in leptospirosis through the activation of Toll-like receptor 2 or the complement system, which stimulates the release of cytokines that lead to the activation of adhesion molecules. The aim of this study was to investigate the involvement of immune pathways and of the intercellular and vascular cell adhesion molecules (intercellular adhesion molecule and vascular cell adhesion molecule, respectively) in the lungs of patients with pulmonary involvement of leptospirosis. We studied the lungs of 18 patients who died of leptospirosis and compared them with 2 groups of controls: normal and noninfectious hemorrhagic lungs. Using immunohistochemistry and image analysis, we quantified the expression of the C3a anaphylatoxin receptor, intercellular adhesion molecule, vascular cell adhesion molecule, and Toll-like receptor 2 in small pulmonary vessels and in the alveolar septa. There was an increased expression of intercellular adhesion molecule (P <.03) and C3a anaphylatoxin receptor (P <.008) in alveolar septa in the leptospirosis group compared with the normal and hemorrhagic controls. In the vessels of the leptospirosis group, there was an increased expression of intercellular adhesion molecule (P=.004), vascular cell adhesion molecule (P=.030), and Toll-like receptor 2 (P=.042) compared with the normal group. Vascular cell adhesion molecule expression in vessels was higher in the leptospirosis group compared with the hemorrhagic group (P=.015). Our results indicate that immune receptors and adhesion molecules participate in the phenomena leading to pulmonary hemorrhage in leptospirosis. (C) 2012 Elsevier Inc. All rights reserved.

Modulation of Maternal Immune System During Pregnancy in the Cow

There is a molecular crosstalk between the trophoblast and maternal immune cells of bovine endometrium. The uterine cells are able to secrete cytokine/chemokines to either induce a suppressive environment for establishment of the pregnancy or to recruit immune cells to the endometrium to fight infections. Despite morphological differences between women and cows, mechanisms for immune tolerance during pregnancy seem to be conserved. Mechanisms for uterine immunesuppression in the cow include: reduced expression of major histocompatability proteins by the trophoblast; recruitment of macrophages to the pregnant endometrium; and modulation of immune-related genes in response to the presence of the conceptus. Recently, an eGFP transgenic cloned embryo model developed by our group showed that there is modulation of foetal proteins expressed at the site of syncytium formation, suggesting that foetal cell can regulate not only by the secretion of specific factors such as interferon-tau, but also by regulating their own protein expression to avoid excessive maternal recognition by the local immune system. Furthermore, foetal DNA can be detected in the maternal circulation; this may reflect the occurrence of an invasion of trophoblast cells and/or their fragment beyond the uterine basement membrane in the cow. In fact, the newly description of exosome release by the trophoblast cell suggests that could be a new fashion of maternal-foetal communication at the placental barrier. Additionally, recent global transcriptome studies on bovine endometrium suggested that the immune system is aware, from an immunological point of view, of the presence of the foetus in the cow during early pregnancy.

Hypoactivity of the central dopaminergic system and autistic-like behavior induced by a single early prenatal exposure to lipopolysaccharide

The aim of the present study was to evaluate the behavioral patterns associated with autism and the prevalence of these behaviors in males and females, to verify whether our model of lipopolysaccharide (LPS) administration represents an experimental model of autism. For this, we prenatally exposed Wistar rats to LPS (100 mu g/kg, intraperitoneally, on gestational day 9.5), which mimics infection by gram-negative bacteria. Furthermore, because the exact mechanisms by which autism develops are still unknown, we investigated the neurological mechanisms that might underlie the behavioral alterations that were observed. Because we previously had demonstrated that prenatal LPS decreases striatal dopamine (DA) and metabolite levels, the striatal dopaminergic system (tyrosine hydroxylase [TH] and DA receptors D1a and D2) and glial cells (astrocytes and microglia) were analyzed by using immunohistochemistry, immunoblotting, and real-time PCR. Our results show that prenatal LPS exposure impaired communication (ultrasonic vocalizations) in male pups and learning and memory (T-maze spontaneous alternation) in male adults, as well as inducing repetitive/restricted behavior, but did not change social interactions in either infancy (play behavior) or adulthood in females. Moreover, although the expression of DA receptors was unchanged, the experimental animals exhibited reduced striatal TH levels, indicating that reduced DA synthesis impaired the striatal dopaminergic system. The expression of glial cell markers was not increased, which suggests that prenatal LPS did not induce permanent neuroinflammation in the striatum. Together with our previous finding of social impairments in males, the present findings demonstrate that prenatal LPS induced autism-like effects and also a hypoactivation of the dopaminergic system. (c) 2012 Wiley Periodicals, Inc.

Dissecting Phaseolus vulgaris Innate Immune System against Colletotrichum lindemuthianum Infection

Background: The genus Colletotrichum is one of the most economically important plant pathogens, causing anthracnose on a wide range of crops including common beans (Phaseolus vulgaris L.). Crop yield can be dramatically decreased depending on the plant cultivar used and the environmental conditions. This study aimed to identify potential genetic components of the bean immune system to provide environmentally friendly control measures against this fungus. Methodology and Principal Findings: As the common bean is not amenable to reverse genetics to explore functionality and its genome is not fully curated, we used putative Arabidopsis orthologs of bean expressed sequence tag (EST) to perform bioinformatic analysis and experimental validation of gene expression to identify common bean genes regulated during the incompatible interaction with C. lindemuthianum. Similar to model pathosystems, Gene Ontology (GO) analysis indicated that hormone biosynthesis and signaling in common beans seem to be modulated by fungus infection. For instance, cytokinin and ethylene responses were up-regulated and jasmonic acid, gibberellin, and abscisic acid responses were down-regulated, indicating that these hormones may play a central role in this pathosystem. Importantly, we have identified putative bean gene orthologs of Arabidopsis genes involved in the plant immune system. Based on experimental validation of gene expression, we propose that hypersensitive reaction as part of effector-triggered immunity may operate, at least in part, by down-regulating genes, such as FLS2-like and MKK5-like, putative orthologs of the Arabidopsis genes involved in pathogen perception and downstream signaling. Conclusions/Significance: We have identified specific bean genes and uncovered metabolic processes and pathways that may be involved in the immune response against pathogens. Our transcriptome database is a rich resource for mining novel defense-related genes, which enabled us to develop a model of the molecular components of the bean innate immune system regulated upon pathogen attack.

The neonatal immune system: immunomodulation of infections in early life

The innate and adaptive immune responses in neonates are usually functionally impaired when compared with their adult counterparts. The qualitative and quantitative differences in the neonatal immune response put them at risk for the development of bacterial and viral infections, resulting in increased mortality. Newborns often exhibit decreased production of Th1-polarizing cytokines and are biased toward Th2-type responses. Studies aimed at understanding the plasticity of the immune response in the neonatal and early infant periods or that seek to improve neonatal innate immune function with adjuvants or special formulations are crucial for preventing the infectious disease burden in this susceptible group. Considerable studies focused on identifying potential immunomodulatory therapies have been performed in murine models. This article highlights the strategies used in the emerging field of immunomodulation in bacterial and viral pathogens, focusing on preclinical studies carried out in animal models with particular emphasis on neonatal-specific immune deficits.

Immunological parameters in elderly women: Correlations with aerobic power, muscle strength and mood state

Purpose: Our objective was to relate immunological data for healthy but sedentary elderly women to aerobic power, strength, and mood state. Methods: We measured peak aerobic power and one-repetition maximum strength along with mood (depression and fatigue), quality of life and carbohydrate intake on 42 women aged 60-77 years. Standard immunological techniques determined natural killer cell count and cytotoxic activity (NKCA), proliferative responses to phytohemaglutinin and OKT3, various lymphocyte subpopulations (CD3(+), CD3(-)CD19(+), CD56(+), CD4(+), CD8(+), CD56(dim) and CD56(bright)), and markers of activation, maturation, down-regulation and susceptibility to apoptosis (CD25(+), CD28(+), CD45RA(+), CD45RO(+), CD69(+), CD95(+), HLA-DR+). Results: Correlations of immune parameters with aerobic power and strength were very similar for absolute and relative immunological data. In the group as a whole, the only correlation with aerobic power was -0.35 (relative CD4(+)CD69(+) count), but in subjects with values <22.6 mL kg(-1) min(-1) correlations ranged from -0.57 (relative CD4(+)CD45RO(+)) to 0.92 (absolute CD56(dim)HLA-DR+). In terms of muscle strength, univariate correlation coefficients ranged from -0.34 (relative and absolute CD3(+)CD4(+)CD8(+)) to +0.48 (absolute CD3(+)HLA-DR+.) and +0.50 (absolute CD8(+)CD45RA(+)CD45RO(+)). Neither NKCA nor lymphocyte proliferation were correlated with aerobic power or muscle strength. Although mood state and quality of life can sometimes be influenced by an individual's fitness level, our multivariate analyses suggested that depression, fatigue and quality of life were more important determinants of immune profile than our fitness measures. Conclusions: Psychological changes associated with aging may have a substantial adverse effect upon the immune system, and immunological function may be enhanced more by addressing these issues than by focusing upon aerobic or resistance training. (C) 2012 Elsevier Inc. All rights reserved.

Inhibitory activity of liposomal flavonoids during oxidative metabolism of human neutrophils upon stimulation with immune complexes and phorbol ester

Context and objective: The massive production of reactive oxygen species by neutrophils during inflammation may cause damage to tissues. Flavonoids act as antioxidants and have anti-inflammatory effects. In this study, liposomes loaded with these compounds were evaluated as potential antioxidant carriers, in attempt to overcome their poor solubility and stability. Materials and methods: Liposomes containing quercetin, myricetin, kaempferol or galangin were prepared by the ethanol injection method and analyzed as inhibitors of immune complex (IC) and phorbol ester-stimulated neutrophil oxidative metabolism by luminol (CLlum) and lucigenin-enhanced (CLluc) chemiluminescence (CL) assays. The mechanisms involved this activity of liposomal flavonoids, such as cytotoxicity and superoxide anion scavenging capacity, and their effect on phagocytosis of ICs were also investigated. Results and discussion: The results showed that the inhibitory effect of liposomal flavonoids on CLlum and CLluc is inversely related to the number of hydroxyl groups in the flavonoid B ring. Moreover, phagocytosis of liposomes by neutrophils does not seem to necessarily promote such activity, as the liposomal flavonoids are also able to reduce CL when the cells are pretreated with cytochalasin B. Under assessed conditions, the antioxidant liposomes are not toxic to the human neutrophils and do not interfere with IC-induced phagocytosis. Conclusion: The studied liposomes can be suitable carriers of flavonoids and be an alternative for the treatment of diseases in which a massive oxidative metabolism of neutrophils is involved.

Characterization of a Novel Oral Glucocorticoid System and Its Possible Role in Disease

Synthetic corticosteroids are used widely for the treatment of a variety of diseases of the mouth. However, little is known as to whether the oral mucosa is able to modulate the local concentration of active corticosteroids or to produce steroids de novo. This has important clinical implications, because tissue-specific regulation of glucocorticoids is a key determinant of the clinical efficacy of these drugs. In the present study, we show that oral fibroblasts and keratinocytes expressed ACTH receptor (MC2R), glucocorticoid receptor (GR), and 11 beta-hydroxysteroid dehydrogenases (11 beta-HSDs). Unlike keratinocytes, fibroblasts lacked 11 beta-HSD2 and could not effectively deactivate exogenously administered cortisol. However, both cell types were able not only to activate cortisone into the active form cortisol, but also to synthesize cortisol de novo following stimulation with ACTH. 11 beta-HSD2, the enzyme controlling cortisol deactivation, exhibited different patterns of expression in normal (squamous epithelium and salivary glands) and diseased oral mucosa (squamous cell carcinoma and mucoepidermoid carcinoma). Blocking of endogenous cortisol catabolism in keratinocytes with the 11 beta-HSD2 inhibitor 18 beta-glycyrrhetinic acid mimicked the effect of exogenous administration of hydrocortisone and partially prevented the detrimental effects induced by pemphigus vulgaris sera. Analysis of the data demonstrates that a novel, non-adrenal glucocorticoid system is present in the oral mucosa that may play an important role in disease.

Toll-like receptor 9 activation: a novel mechanism linking placenta-derived mitochondrial DNA and vascular dysfunction in pre-eclampsia

Emerging evidence suggests that in addition to being the 'power houses' of our cells, mitochondria facilitate effector responses of the immune system. Cell death and injury result in the release of mtDNA (mitochondrial DNA) that acts via TLR9 (Toll-like receptor 9), a pattern recognition receptor of the immune system which detects bacterial and viral DNA but not vertebrate DNA. The ability of mtDNA to activate TLR9 in a similar fashion to bacterial DNA stems from evolutionarily conserved similarities between bacteria and mitochondria. mtDNA may be the trigger of systemic inflammation in pathologies associated with abnormal cell death. PE (pre-eclampsia) is a hypertensive disorder of pregnancy with devastating maternal and fetal consequences. The aetiology of PE is unknown and removal of the placenta is the only effective cure. Placentas from women with PE show exaggerated necrosis of trophoblast cells, and circulating levels of mtDNA are higher in pregnancies with PE. Accordingly, we propose the hypothesis that exaggerated necrosis of trophoblast cells results in the release of mtDNA, which stimulates TLR9 to mount an immune response and to produce systemic maternal inflammation and vascular dysfunction that lead to hypertension and IUGR (intra-uterine growth restriction). The proposed hypothesis implicates mtDNA in the development of PE via activation of the immune system and may have important preventative and therapeutic implications, because circulating mtDNA may be potential markers of early detection of PE, and anti-TLR9 treatments may be promising in the management of the disease.

Thymopoiesis and regulatory T cells in healthy children and adolescents

OBJECTIVES: The purpose of this study was to investigate the association between T cell receptor excision circle levels in peripheral blood mononuclear cells and regulatory T cells that co-express CD25 and Foxp3 in healthy children and adolescents of different ages. MATERIALS AND METHODS: The quantification of signal-joint T-cell receptor excision circle levels in the genomic DNA of peripheral blood mononuclear cells was performed using real-time quantitative PCR. The analysis of CD4, CD8, CD25, and Foxp3 expression was performed using flow cytometry. RESULTS: Ninety-five healthy controls (46 females and 49 males) ranging in age from 1 to 18 years were analyzed. The mean T-cell receptor excision circle count in all individuals was 89.095 +/- 36.790 T-cell receptor excision circles per microgram of DNA. There was an inverse correlation between T-cell receptor excision circles counts and age (r = -0.846; p < 0.001) as well as between the proportion of CD4(+)CD25(+)Foxp3(+) T cells and age (r = -0.467; p = 0.04). In addition, we observed a positive correlation between the amount of CD4(+)CD25(+)Foxp3(+) T cells and the amount of T-cell receptor excision circles per microgram of DNA in individuals of all ages (r = -0.529; p = 0.02). CONCLUSIONS: In this study, we observed a decrease in the thymic function with age based on the fact that the level of T-cell receptor excision circles in the peripheral blood positively correlated with the proportion of regulatory T cells in healthy children and adolescents. These findings indicate that although T-cell receptor excision circles and regulatory T cells levels decrease with age, homeostasis of the immune system and relative regulatory T cells population levels are maintained in the peripheral blood.

MyD88 Signaling Pathway Is Involved in Renal Fibrosis by Favoring a T(H)2 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 (TH2)-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 TH2 cytokine production and decreased fibrosis formation. Moreover, TLR2, TLR4 and MyD88 KO animals exhibited less M2 macrophage infiltration, namely interleukin (IL)-10+ and CD206+ CD11bhigh cells, at 7 d after surgery. We evaluated the role of a TH2 cytokine in this context, and observed that the absence of IL-4 was associated with better renal function, decreased IL-13 and TGF- β 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 TH1:TH2 balance, as TH2 and M2 cells are predictive of fibrosis toward mechanisms that are sensed by innate immune response and triggered in a MyD88-dependent pathway.

Immune response and tolerability of varicella vaccine in children and adolescents with systemic lupus erythematosus previously exposed to varicella-zoster virus

Objectives The aim of the present paper is to evaluate the immune response and tolerability of varicella vaccine in children and adolescents with systemic lupus erythematosus previously exposed to varicella-zoster virus. Methods We performed a prospective and controlled study on a group of 54 SLE patients that were chosen at random to be or not to be vaccinated (28 were vaccinated and 26 were not). Twenty-eight healthy controls, of matching age and sex were also vaccinated. All were submitted to a questionnaire, physical evaluation and laboratory assays: lymphocyte immuno-phenotyping by flow cytometry, plasma varicella zoster virus (VZV) serology by ELISA and in vitro interferon gamma (IFN gamma) production by T-cells after stimulus with VZV antigen. They were evaluated before vaccination and at 30, 45, 180 and 360 days afterwards. Results We did not observe any differences in the frequency of adverse events in both vaccinated groups. At study entry, all individuals were seropositive for VZV antibodies. The serum VZV antibody titres similarly increased after vaccination. The frequency of flares and the SLEDAI score were also similar among the patients. Thirty days after vaccination the production of IFN gamma specific to VZV was lower in the SLE group compared to healthy, controls. In the follow-up we observed 4 cases of herpes zoster in the SLE unvaccinated group, but no zoster in the vaccinated group. Conclusion The varicella vaccine was well tolerated in SLE group, who had pre-existing immunity to varicella. The varicella vaccine immunogenicity measurement by serum antibody titres was appropriate. The incidence of HZ was lower in the vaccinated lupus group.

Lipopolysaccharide-Induced Sickness Behaviour Evaluated in Different Models of Anxiety and Innate Fear in Rats

The fact that there is a complex and bidirectional communication between the immune and nervous systems has been well demonstrated. Lipopolysaccharide (LPS), a component of gram-negative bacteria, is widely used to systematically stimulate the immune system and generate profound physiological and behavioural changes, also known as sickness behaviour (e.g. anhedonia, lethargy, loss of appetite, anxiety, sleepiness). Different ethological tools have been used to analyse the behavioural modifications induced by LPS; however, many researchers analysed only individual tests, a single LPS dose or a unique ethological parameter, thus leading to disagreements regarding the data. In the present study, we investigated the effects of different doses of LPS (10, 50, 200 and 500 mu g/kg, i.p.) in young male Wistar rats (weighing 180200 g; 89 weeks old) on the ethological and spatiotemporal parameters of the elevated plus maze, light-dark box, elevated T maze, open-field tests and emission of ultrasound vocalizations. There was a dose-dependent increase in anxiety-like behaviours caused by LPS, forming an inverted U curve peaked at LPS 200 mu g/kg dose. However, these anxiety-like behaviours were detected only by complementary ethological analysis (stretching, grooming, immobility responses and alarm calls), and these reactions seem to be a very sensitive tool in assessing the first signs of sickness behaviour. In summary, the present work clearly showed that there are resting and alertness reactions induced by opposite neuroimmune mechanisms (neuroimmune bias) that could lead to anxiety behaviours, suggesting that misunderstanding data could occur when only few ethological variables or single doses of LPS are analysed. Finally, it is hypothesized that this bias is an evolutionary tool that increases animals security while the body recovers from a systemic infection.