Activation of PPAR-γ reduces HPA axis activity in diabetic rats by up-regulating PI3K expression.

Increased hypothalamus-pituitary-adrenal axis (HPA) activity in diabetes is strongly associated with several morbidities noted in patients with the disease. We previously demonstrated that hyperactivity of HPA axis under diabetic conditions is associated with up-regulation of adrenocorticotrophic hormone (ACTH) receptors (MC2R) in adrenal and down-regulation of glucocorticoid receptors (GR and MR) in pituitary. This study investigates the role of peroxisome proliferator-activated receptor (PPAR)-γ in HPA axis hyperactivity in diabetic rats. Diabetes was induced by intravenous injection of alloxan into fasted rats. The PPAR-γ agonist rosiglitazone and/or PI3K inhibitor wortmannin were administered daily for 18 consecutive days, starting 3days after diabetes induction. Plasma ACTH and corticosterone were evaluated by radioimmunoassay, while intensities of MC2R, proopiomelanocortin (POMC), GR, MR, PI3K p110α and PPAR-γ were assessed using immunohistochemistry. Rosiglitazone treatment inhibited adrenal hypertrophy and hypercorticoidism observed in diabetic rats. Rosiglitazone also significantly reversed the diabetes-induced increase in the MC2R expression in adrenal cortex. We noted that rosiglitazone reduced the number of corticotroph cells and inhibited both anterior pituitary POMC expression and plasma ACTH levels. Furthermore, rosiglitazone treatment was unable to restore the reduced expression of GR and MR in the anterior pituitary of diabetic rats. Rosiglitazone increased the number of PPAR-γ+ cells and expression of PI3K p110α in both anterior pituitary and adrenal cortex of diabetic rats. In addition, wortmannin blocked the ability of rosiglitazone to restore corticotroph cell numbers, adrenal hypertrophy and plasma corticosterone levels in diabetic rats. In conclusion, our findings revealed that rosiglitazone down-regulates HPA axis hyperactivity in diabetic rats via a mechanism dependent on PI3K activation in pituitary and adrenal glands.

Cardiac microvascular rarefaction in hyperthyroidism-induced left ventricle dysfunction.

OBJECTIVE: The pathophysiology underlying hyperthyroidism-induced left ventricle (LV) dysfunction and hypertrophy directly involves the heart and indirectly involves the neuroendocrine systems. The effects of hyperthyroidism on the microcirculation are still controversial in experimental models. We investigated the effects of hyperthyroidism on the cardiac function and microcirculation of an experimental rat model. METHODS: Male Wistar rats (170-250 g) were divided into two groups: the euthyroid group (n = 10), which was treated with 0.9% saline solution, and the hyperthyroid group (n = 10), which was treated with l-thyroxine (600 µg/kg/day, i.p.) during 14 days. An echocardiographic study was performed to evaluate the alterations in cardiac function, structure and geometry. The structural capillary density and the expression of angiotensin II AT1 receptor in the LV were analyzed using histochemistry and immunohistochemistry, respectively. RESULTS: Hyperthyroidism was found to induce profound cardiovascular alterations, such as systolic hypertension, tachycardia, LV dysfunction, cardiac hypertrophy, and myocardial fibrosis. This study demonstrates the existence of structural capillary rarefaction and the down-regulation of the cardiac angiotensin II AT1 receptor in the myocardium of hyperthyroid rats in comparison with euthyroid rats. CONCLUSIONS: Microvascular rarefaction may be involved in the pathophysiology of hyperthyroidism-induced cardiovascular alterations.

Lessons from the Cerebrospinal Fluid Analysis of HTLV-1-Infected Individuals: Biomarkers of Inflammation for HAM/TSP Development.

HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is a neurodegenerative disease that leads to motor impairment due to a chronic inflammatory process in the central nervous system (CNS). However, the HAM/TSP pathogenesis is not completely clear, and biomarkers to define the disease prognosis are still necessary. Thus, we aimed to identify biomarkers for HAM/TSP and potential mechanisms involved in disease development. To that end, the concentrations of VILIP-1, BDNF, VEGF, ß-NGF, TGF-ß1, fractalkine/CX3CL1, IL-6, IL-18, and TNF-α, and the soluble forms of TREM-1, TREM-2, and RAGE, were assessed using a multiplex bead-based immunoassay in paired cerebrospinal fluid (CSF) and serum samples from HAM/TSP patients (n = 20), asymptomatic HTLV-1 carriers (AC) (n = 13), and HTLV-1-seronegative individuals (n = 9), with the results analyzed according to the speed of HAM/TSP progression. HAM/TSP patients had elevated fractalkine in the serum but not in the CSF, particularly those with low neuroinflammatory activity (CSF/serum ratio of neopterin <1 and of CXCL10 < 2). HAM/TSP patients with normal CSF levels of neurofilament light chain (NfL) showed elevated ß-NGF in serum, and serum BDNF levels were increased in HTLV-1-infected individuals, particularly in HTLV-1 AC. Both HTLV-1 AC and HAM/TSP patients had lower TGF-ß1 levels in CSF compared to uninfected individuals, and HAM/TSP patients with active CNS inflammation showed higher CSF levels of IL-18, which correlated with markers of inflammation, neuronal death, and blood−brain-barrier permeability. Although none of the factors evaluated were associated with the speed of HAM/TSP progression, reduced TGF-ß1 levels in CSF suggest that suppressive responses to control subclinical and/or active neurodegeneration are impaired, while increased CSF IL-18 indicates the involvement of inflammasome-mediated mechanisms in HAM/TSP development.

Following the Clues: Usefulness of Biomarkers of Neuroinflammation and Neurodegeneration in the Investigation of HTLV-1-Associated Myelopathy Progression.

Human T-lymphotropic virus type 1 (HTLV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is a neurodegenerative disease due to axonal damage of the corticospinal secondary to an inflammatory response against infected T-cells. In the present work, we aimed to evaluate biomarkers of neurodegeneration and neuroinflammation in the definition of HAM/TSP prognosis. Neurofilament light (NfL) and phosphorylated heavy (pNfH) chains, total Tau protein, cellular prion protein (PrPc), inflammatory chemokines, and neopterin were quantified in paired cerebrospinal fluid (CSF) and serum samples from HAM/TSP patients (n=21), HTLV-1 asymptomatic carriers (AC) (n=13), and HTLV-1 seronegative individuals with non-inflammatory non-degenerative neurological disease (normal-pressure hydrocephalus) (n=9) as a control group. HTLV-1 proviral load in peripheral blood mononuclear cells and the expression of chemokine receptors CCR4, CCR5, and CXCR3 in infected CD4+ T-cells (HTLV-1 Tax+ cells) were also assessed. CSF levels of Tau, NfL, and pNfH were similar between groups, but PrPc and neopterin were elevated in HAM/TSP patients. Most individuals in the control group and all HTLV-1 AC had CSF/serum neopterin ratio < 1.0, and two-thirds of HAM/TSP patients had ratio values > 1.0, which positively correlated with the speed of disease progression and pNfH levels, indicating active neuroinflammation. HAM/TSP patients showed high serum levels of CXCR3-binding chemokines (CXCL9, CXCL10, and CXCL11) and elevated CSF levels of CCL2, CCL3, CCL4, CCL17, CXCL5, CXCL10, and CXCL11. Indeed, CXCL10 concentration in CSF of HAM/TSP patients was 5.8-fold and 8.7-fold higher in than in HTLV-1 AC and controls, respectively, and correlated with CSF cell counts. HAM/TSP patients with typical/rapid disease progression had CSF/serum CXCL10 ratio > 1.0 and a higher frequency of CXCR3+Tax+CD4+ T-cells in blood, which indicated a positive gradient for the migration of infected cells and infiltration into the central nervous system. In conclusion, the slow progression of HAM/TSP abrogates the usefulness of biomarkers of neuronal injury for the disease prognosis. Thus, markers of inflammation provide stronger evidence for HAM/TSP progression, particularly the CSF/serum neopterin ratio, which may contribute to overcome differences between laboratory assays.

Omega-9 Oleic Acid, the Main Compound of Olive Oil, Mitigates Inflammation during Experimental Sepsis.

The Mediterranean diet, rich in olive oil, is beneficial, reducing the risk of cardiovascular diseases and cancer. Olive oil is mostly composed of the monounsaturated fatty acid omega-9. We showed omega-9 protects septic mice modulating lipid metabolism. Sepsis is initiated by the host response to infection with organ damage, increased plasma free fatty acids, high levels of cortisol, massive cytokine production, leukocyte activation, and endothelial dysfunction. We aimed to analyze the effect of omega-9 supplementation on corticosteroid unbalance, inflammation, bacterial elimination, and peroxisome proliferator-activated receptor (PPAR) gamma expression, an omega-9 receptor and inflammatory modulator. We treated mice for 14 days with omega-9 and induced sepsis by cecal ligation and puncture (CLP). We measured systemic corticosterone levels, cytokine production, leukocyte and bacterial counts in the peritoneum, and the expression of PPAR gamma in both liver and adipose tissues during experimental sepsis. We further studied omega-9 effects on leukocyte rolling in mouse cremaster muscle-inflamed postcapillary venules and in the cerebral microcirculation of septic mice. Here, we demonstrate that omega-9 treatment is associated with increased levels of the anti-inflammatory cytokine IL-10 and decreased levels of the proinflammatory cytokines TNF-α and IL-1ß in peritoneal lavage fluid of mice with sepsis. Omega-9 treatment also decreased systemic corticosterone levels. Neutrophil migration from circulation to the peritoneal cavity and leukocyte rolling on the endothelium were decreased by omega-9 treatment. Omega-9 also decreased bacterial load in the peritoneal lavage and restored liver and adipose tissue PPAR gamma expression in septic animals. Our data suggest a beneficial anti-inflammatory role of omega-9 in sepsis, mitigating leukocyte rolling and leukocyte influx, balancing cytokine production, and controlling bacterial growth possibly through a PPAR gamma expression-dependent mechanism. The significant reduction of inflammation detected after omega-9 enteral injection can further contribute to the already known beneficial properties facilitated by unsaturated fatty acid-enriched diets.

Curine inhibits mast cell-dependent responses in mice.

ETHNOPHARMACOLOGICAL RELEVANCE: Curine is a bisbenzylisoquinoline alkaloid and the major constituent isolated from Chondrodendron platyphyllum, a plant that is used to treat inflammatory diseases in Brazilian folk medicine. This study investigates the effectiveness of curine on mast cell-dependent responses in mice. MATERIALS AND METHODS: To induce mast cell-dependent responses, Swiss mice were subcutaneously sensitized with ovalbumin (OVA-12 µg/mouse) and Al(OH)3 in a 0.9% NaCl solution. Fifteen days later, the animals were challenged with OVA through different pathways. Alternatively, the animals were injected with compound 48/80 or histamine, and several parameters, including anaphylaxis, itching, edema and inflammatory mediator production, were analyzed. Promethazine, cromoglycate, and verapamil were used as control drugs, and all of the treatments were performed 1h before the challenges. RESULTS: Curine pre-treatment significantly inhibited the scratching behavior and the paw edema induced by either compound 48/80 or OVA, and this protective effect was comparable in magnitude with those associated with treatment with either cromoglycate or verapamil. In contrast, curine was a weak inhibitor of histamine-induced paw edema, which was completely inhibited by promethazine. Curine and verapamil significantly inhibited pleural protein extravasations and prostaglandin D2 (PGD2) and cysteinyl leukotrienes (CysLTs) production following allergen-induced pleurisy. Furthermore, like verapamil, curine inhibited the anaphylactic shock caused by either compound 48/80 or an allergen. In in vitro settings, these treatments also inhibited degranulation as well as PGD2 and CysLT production through IgE-dependent activation of the mast cell lineage RBL-2H3. CONCLUSION: Curine significantly inhibited immediate allergic reactions through mechanisms more related to mast cell stabilization and activation inhibition than interference with the pro-inflammatory effects of mast cell products. These findings are in line with the hypothesis that the alkaloid curine may be beneficial for the treatment of allergic disorders.

Papel do receptor nuclear PPAR-gamma na redução do número e reatividade de mastócitos observada em animais diabéticos / Role of the peroxisome proliferator-actived receptor (PPAR)-gamma in the reduction of mast cell number and reactivity observed in diabetic animals

O estado diabético está associado à redução no número e ao comprometimento da funcionalidade de mastócitos. A partir disso, este trabalho foi realizado com intuito de investigar o papel do receptor ativado por proliferadores de peroxissomos (PPAR)-gamma na redução do número e reatividade de mastócitos em ratos diabéticos. O efeito da ativação do PPAR-gamma sobre a apoptose dos mastócitos também foi avaliada. A diabetes foi induzida através de uma injeção única de aloxana (40 mg/Kg) em animais que se encontravam em jejum. Após três dias da indução da diabetes, o ligante agonista de PPAR-gamma rosiglitazona (0,5 mg/Kg) e/ou o antagonista específico do mesmo receptor GW9662 (0,5 mg/Kg) foram administrados uma vez ao dia durante 18 dias consecutivos. A taxa de apoptose dos mastócitos e os níveis hormonais foram determinados pela análise da fragmentação de DNA e por radioimunoensaio, respectivamente. O tratamento com rosiglitazona restaurou o número de mastócitos na cavidade torácica e no tecido mesentérico dos ratos diabéticos. Além disso, o tratamento dos animais diabéticos com rosiglitazona restabeleceu a liberação normal de histamina dos mastócitos após estimulação antigênica in vitro, avaliada por fluorimetria. O aumento da apoptose dos mastócitos em animais diabéticos foi inibida com a rosiglitazona. Observamos ainda que o aumento nos níveis circulantes de corticosterona associado com a disfunção mastocitária em ratos diabéticos é sensível ao tratamento com o agonista de PPAR-gamma. Em adição, o bloqueio do receptor PPAR-gamma com GW9662 suprimiu a capacidade da rosiglitazona em normalizar os níveis de glicocorticóides bem como restaurar o número de mastócitos.

Utilizando imunohistoquímicas, constatamos que a ativação do PPAR-gamma no eixo hipotálamo-pituitária-adrenal (HPA) de animais diabéticos reduziu a expressão do receptor do hormônio adrenocorticotrófico (ACTH) MC2-R, bem como do receptor de glicocorticóides (GR), nas adrenais e hipófise, respectivamente, desses animais. Finalmente, nós mostramos que o aumento nos níveis de ACTH no plasma dos animais diabéticos foi reduzido pelo tratamento com rosiglitazona. Como conclusão, nossos achamos mostram que a rosiglitazona restaura o número e reatividade dos mastócitos de animais diabéticos, acompanhado pela redução da apoptose dessas células, em paralelo com a atenuação da elevada secreção de glicocorticóides, indicando que o PPAR-gamma tem um papel importante nesse fenômeno.