Systemic inflammatory challenges compromise survival after experimental stroke via augmenting brain inflammation, blood- brain barrier damage and brain oedema independently of infarct size

<p>Abstract</p> <p>Background</p> <p>Systemic inflammation impairs outcome in stroke patients and experimental animals via mechanisms which are poorly understood. Circulating inflammatory mediators can activate cerebrovascular endothelium or glial cells in the brain and impact on ischaemic brain injury. One of the most serious early clinical complications of cerebral ischaemia is brain oedema, which compromises survival in the first 24-48 h. It is not understood whether systemic inflammatory challenges impair outcome after stroke by increasing brain injury only or whether they have direct effects on brain oedema, cerebrovascular inflammation and blood-brain barrier damage.</p> <p>Methods</p> <p>We used two different systemic inflammatory stimuli, acute endotoxin treatment and anaphylaxis to study mechanisms of brain injury after middle cerebral artery occlusion (MCAo). Ischaemic brain injury, blood-brain barrier damage and oedema were analysed by histological techniques. Systemic cytokine responses and inflammatory changes in the brain were analysed by cytometric bead array, immunofluorescence, <it>in situ </it>hibridization and quantitative real-time PCR.</p> <p>Results</p> <p>Systemic inflammatory challenges profoundly impaired survival in the first 24 h after experimental stroke in mice, independently of an increase in infarct size. Systemic lipopolysaccharide (LPS) dose-dependently increased mortality (50-100%) minutes to hours after cerebral ischaemia. Acute anaphylactic challenge in ovalbumin-sensitised mice affected stroke more seriously when induced via intraperitoneal administration compared to intravenous. Both LPS and anaphylaxis induced inflammatory changes in the blood and in the brain prior to experimental stroke. Plasma cytokine levels were significantly higher after LPS, while increased IL-10 levels were seen after anaphylaxis. After MCAo, both LPS and anaphylaxis increased microglial interleukin-1α (IL-1α) expression and blood-brain barrier breakdown. LPS caused marked granulocyte recruitment throughout the ipsilateral hemisphere. To investigate whether reduction of ischaemic damage can improve outcome in systemic inflammation, controlled hypothermia was performed. Hypothermia reduced infarct size in all treatment groups and moderately improved survival, but failed to reduce excess oedema formation after anaphylaxis and LPS-induced neuroinflammation.</p> <p>Conclusions</p> <p>Our results suggest that systemic inflammatory conditions induce cerebrovascular inflammation via diverse mechanisms. Increased brain inflammation, blood-brain barrier injury and brain oedema formation can be major contributors to impaired outcome in mice after experimental stroke with systemic inflammatory stimuli, independently of infarct size.</p

Brown adipose tissue in obesity: Fractalkine-receptor dependent immune cell recruitment affects metabolic-related gene expression.

Brown adipose tissue (BAT) plays essential role in metabolic- and thermoregulation and displays morphological and functional plasticity in response to environmental and metabolic challenges. BAT is a heterogeneous tissue containing adipocytes and various immune-related cells, however, their interaction in regulation of BAT function is not fully elucidated. Fractalkine is a chemokine synthesized by adipocytes, which recruits fractalkine receptor (CX3CR1)-expressing leukocytes into the adipose tissue. Using transgenic mice, in which the fractalkine receptor, Cx3cr1 gene was replaced by Gfp, we evaluated whether deficiency in fractalkine signaling affects BAT remodeling and function in high-fat-diet - induced obesity. Homo- and heterozygote male CX3CR1-GFP mice were fed with normal or fat enriched (FatED) diet for 10weeks. Interscapular BAT was collected for molecular biological analysis. Heterozygous animals in which fractalkine signaling remains intact, gain more weight during FatED than CX3CR1 deficient gfp/gfp homozygotes. FatED in controls resulted in macrophage recruitment to the BAT with increased expression of proinflammatory mediators (Il1a, b, Tnfa and Ccl2). Local BAT inflammation was accompanied by increased expression of lipogenic enzymes and resulted in BAT "whitening". By contrast, fractalkine receptor deficiency prevented accumulation of tissue macrophages, selectively attenuated the expression of Tnfa, Il1a and Ccl2, increased BAT expression of lipolytic enzymes (Atgl, Hsl and Mgtl) and upregulated genes involved thermo-metabolism (Ucp1, Pparg Pgc1a) in response to FatED. These results highlight the importance of fractalkine-CX3CR1 interaction in recruitment of macrophages into the BAT of obese mice which might contribute to local tissue inflammation, adipose tissue remodeling and regulation of metabolic-related genes

Differential Changes in Expression of Stress- and Metabolic-related Neuropeptides in the Rat Hypothalamus during Morphine Dependence and Withdrawal

Chronic morphine treatment and naloxone precipitated morphine withdrawal activates stress-related brain circuit and results in significant changes in food intake, body weight gain and energy metabolism. The present study aimed to reveal hypothalamic mechanisms underlying these effects. Adult male rats were made dependent on morphine by subcutaneous implantation of constant release drug pellets. Pair feeding revealed significantly smaller weight loss of morphine treated rats compared to placebo implanted animals whose food consumption was limited to that eaten by morphine implanted pairs. These results suggest reduced energy expenditure of morphine-treated animals. Chronic morphine exposure or pair feeding did not significantly affect hypothalamic expression of selected stress- and metabolic related neuropeptides - corticotropin-releasing hormone (CRH), urocortin 2 (UCN2) and proopiomelanocortin (POMC) compared to placebo implanted and pair fed animals. Naloxone precipitated morphine withdrawal resulted in a dramatic weight loss starting as early as 15-30 min after naloxone injection and increased adrenocorticotrophic hormone, prolactin and corticosterone plasma levels in morphine dependent rats. Using real-time quantitative PCR to monitor the time course of relative expression of neuropeptide mRNAs in the hypothalamus we found elevated CRH and UCN2 mRNA and dramatically reduced POMC expression. Neuropeptide Y (NPY) and arginine vasopressin (AVP) mRNA levels were transiently increased during opiate withdrawal. These data highlight that morphine withdrawal differentially affects expression of stress- and metabolic-related neuropeptides in the rat hypothalamus, while relative mRNA levels of these neuropeptides remain unchanged either in rats chronically treated with morphine or in their pair-fed controls

Comparison of Stress-Induced Changes in Adults and Pups: Is Aldosterone the Main Adrenocortical Stress Hormone during the Perinatal Period in Rats?

Positive developmental impact of low stress-induced glucocorticoid levels in early development has been recognized for a long time, while possible involvement of mineralocorticoids in the stress response during the perinatal period has been neglected. The present study aimed at verifying the hypothesis that balance between stress-induced glucocorticoid and mineralocorticoid levels is changing during postnatal development. Hormone responses to two different stressors (insulin-induced hypoglycaemia and immune challenge induced by bacterial lipopolysaccharid) measured in 10-day-old rats were compared to those in adults. In pups corticosterone responses to both stressors were significantly lower than in adults, which corresponded well with the stress hyporesponsive period. Importantly, stress-induced elevations in aldosterone concentration were significantly higher in pups compared both to corticosterone elevations and to those in adulthood with comparable adrenocorticotropin concentrations in the two age groups. Greater importance of mineralocorticoids compared to glucocorticoids in postnatal period is further supported by changes in gene expression and protein levels of gluco- (GR) and mineralocorticoid receptors (MR) and selected enzymes measured by quantitative PCR and immunohystochemistry in the hypothalamus, hippocampus, prefrontal cortex, liver and kidney. Gene expression of 11beta-hydroxysteroid dehydrogenase 2 (11beta-HSD2), an enzyme enabling preferential effects of aldosterone on mineralocorticoid receptors, was higher in 10-day-old pups compared to adult animals. On the contrary, the expression and protein levels of GR, MR and 11beta-HSD1 were decreased. Presented results clearly show higher stress-induced release of aldosterone in pups compared to adults and strongly suggest greater importance of mineralocorticoids compared to glucocorticoids in stress during the postnatal period

The fractalkine/Cx3CR1 system is implicated in the development of metabolic visceral adipose tissue inflammation in obesity.

Diet-induced obesity and related peripheral and central inflammation are major risk factors for metabolic, neurological and psychiatric diseases. The chemokine fractalkine (Cx3CL1) and its receptor Cx3CR1 play a pivotal role in recruitment, infiltration and proinflammatory polarization of leukocytes and micoglial cells, however, the role of fractalkine signaling in the development of metabolic inflammation is not fully resolved. To address this issue, fractalkine receptor deficient (Cx3CR1 gfp/gfp) mice were exposed to normal or fat-enriched diet (FatED) for 10weeks and physiological-, metabolic- and immune parameters were compared to those animals in which the fractalkine signaling is maintained by the presence of one functioning allele (Cx3CR1 +/gfp). Mice with intact fractalkine signaling develop obesity characterized by increased epididymal white fat depots and mild glucose intolerance, recruit leukocytes into the visceral adipose tissue and display increased expression of subset of pro- and anti-inflammatory cytokines when exposed to fat-enriched diet. By contrast, Cx3CR1-deficient (gfp/gfp) mice gain significantly less weight on fat-enriched diet and have smaller amount of white adipose tissue (WAT) in the visceral compartment than heterozygote controls. Furthermore, Cx3CR1 gfp/gfp mice fed a fat-enriched diet do not develop glucose intolerance, recruit proportionally less number of gfp-positive cells and express significantly less MCP-1, IL-1alpha and TNFalpha in the WAT than control animals with fat-enriched diet induced obesity. Furthermore, heterozygote obese, but not fractalkine receptor deficient mice express high levels of anti-inflammatory IL-10 and arginase1 markers in the visceral fat. The effect of fat-enriched diet on cytokine expression pattern was specific for the WAT, as we did not detect significant elevation of interleukin-1, tumor necrosis factor-alpha and monocyte chemotacting protein (MCP-1) expression in the liver or in the hypothalamus in either genotype. These results highlight the importance of fractalkine signaling in recruitment and polarization of adipose tissue immune cells and identify fractalkine as a target to fight obesity-induced inflammatory complications

Regulation of mouse microglia activation and effector functions by bone marrow-derived mesenchymal stem cells

Mesenchymal stem or stromal cells (MSCs) are rare multipotent cells with potent regenerative and immunomodulatory properties. Microglial cells are specialized tissue macrophages of the central nervous system (CNS) that continuously survey their environment with highly motile extensions. Recently several studies have shown that MSCs are capable of reprogramming microglia into an “M2-like” phenotype characterized by increased phagocytic activity and upregulated expression of anti- inflammatory mediators in vitro. However, the precise polarization states of microglia in the presence of MSCs under physiological or under inflammatory conditions remain largely unknown. In this study, we found that MSCs induce a mixed microglia phenotype defined as Arg-1-high, CD86-high, CD206-high, IL-10-high, PGE2-high, MCP-1/CCL2-high, IL-1β- moderate, NALP-3-low, and TNF-α-low cells. These MSC-elicited microglial cells have high phagocytic activity and antigen-presenting ability. Lipopolysaccharide (LPS) is able to shape this microglia phenotype quantitatively, but not qualitatively in the presence of MSCs. This unique polarization state resembles a novel regulatory microglia phenotype, which might contribute to the resolution of inflammation and to tissue repair in the CNS

Oligomannan Prebiotic Attenuates Immunological, Clinical and Behavioral Symptoms in Mouse Model of Inflammatory Bowel Disease

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Xenoestrogens Ethinyl Estradiol and Zearalenone Cause Precocious Puberty in Female Rats via Central Kisspeptin Signaling

Xenoestrogens from synthetic or natural origin represent an increasing risk of disrupted endocrine functions including the physiological activity of the hypothalamo-pituitary-gonad axis. Ethinyl estradiol (EE2) is a synthetic estrogen used in contraceptive pills, whereas zearalenone (ZEA) is a natural mycoestrogen found with increasing prevalence in various cereal crops. Both EE2 and ZEA are agonists of estrogen receptor alpha (ERalpha) and accelerate puberty. However, the neuroendocrine mechanisms that are responsible for this effect remain unknown. Immature female Wistar rats were treated with EE2 (10 mu g/kg), ZEA (10 mg/kg) or vehicle for 10 days starting from postnatal day 18. As a marker of puberty, vaginal opening was recorded and neuropeptide- and related transcription factor mRNA levels were measured by quantitative real time PCR and in situ hybridization histochemistry. Both ZEA and EE2 accelerated vaginal opening, increased uterine weight and the number of antral follicles in the ovary and resulted in increased central expression of gnrh. These changes occurred in parallel with an earlier increase of kiss1 mRNA in the anteroventral and rostral periventricular (AVPV/PeV) hypothalamus, and increased kisspeptin (KP) fiber density and KP-GnRH appositions in the preoptic area. These changes are compatible with a mechanism in which xenoestrogens overstimulate the developmentally unprepared reproductive system, which results in advanced vaginal opening and enlargement of the uterus at the periphery. Within the hypothalamus, ZEA and EE2 directly activate AVPV KP neurons to stimulate GnRH mRNA. However, GnRH and gonadotropin release and ovulation are disrupted due to xenoestrogen-mediated inhibitory KP signaling in the arcuate nucleus