Microparticles from apoptotic platelets promote resident macrophage differentiation

Platelets shed microparticles not only upon activation, but also upon ageing by an apoptosis-like process (apoptosis-induced platelet microparticles, PMap). While the activation-induced microparticles have widely been studied, not much is known about the (patho)physiological consequences of PMap formation. Flow cytometry and scanning electron microscopy demonstrated that PMap display activated integrins and interact to form microparticle aggregates. PMap were chemotactic for monocytic cells, bound to these cells, an furthermore stimulated cell adhesion and spreading on a fibronectin surface. After prolonged incubation, PMap promoted cell differentiation, but inhibited proliferation. Monocyte membrane receptor analysis revealed increased expression levels of CD11b (integrin αMβ2), CD14 and CD31 (platelet endothelial cell adhesion molecule-1), and the chemokine receptors CCR5 and CXCR4, but not of CCR2. This indicated that PMap polarized the cells into resident M2 monocytes. Cells treated with PMap actively consumed oxidized low-density lipoprotein (oxLDL), and released matrix metalloproteinases and hydrogen peroxide. Further confirmation for the differentiation towards resident professional phagocytes came from the finding that PMap stimulated the expression of the (ox)LDL receptors, CD36 and CD68, and the production of proinflammatory and immunomodulating cytokines by monocytes. In conclusion, interaction of PMap with monocytic cells has an immunomodulating potential. The apoptotic microparticles polarize the cells into a resident M2 subset, and induce differentiation to resident professional phagocytes

Genome-wide analyses identify a role for SLC17A4 and AADAT in thyroid hormone regulation

Thyroid dysfunction is an important public health problem, which affects 10% of the general population and increases the risk of cardiovascular morbidity and mortality. Many aspects of thyroid hormone regulation have only partly been elucidated, including its transport, metabolism, and genetic determinants. Here we report a large meta-analysis of genome-wide association studies for thyroid function and dysfunction, testing 8 million genetic variants in up to 72,167 individuals. One-hundred-and-nine independent genetic variants are associated with these traits. A genetic risk score, calculated to assess their combined effects on clinical end points, shows significant associations with increased risk of both overt (Graves' disease) and subclinical thyroid disease, as well as clinical complications. By functional follow-up on selected signals, we identify a novel thyroid hormone transporter (SLC17A4) and a metabolizing enzyme (AADAT). Together, these results provide new knowledge about thyroid hormone physiology and disease, opening new possibilities for therapeutic targets

Attenuation of Congenital Portosystemic Shunt Reduces Inflammation in Dogs

Liver disease is a major cause of morbidity and mortality. One of the most significant complications in patients with liver disease is the development of neurological disturbances, termed hepatic encephalopathy. The pathogenesis of hepatic encephalopathy is incompletely understood, which has resulted in the development of a wide range of experimental models. Congenital portosystemic shunt is one of the most common congenital disorders diagnosed in client owned dogs. Our recent studies have demonstrated that the pathophysiology of canine hepatic encephalopathy is very similar to human hepatic encephalopathy, which provides strong support for the use of dogs with a congenital portosystemic shunt as a naturally occurring model of human hepatic encephalopathy. Specifically, we have demonstrated an important role for ammonia and inflammation in the development of hepatic encephalopathy in dogs with a congenital portosystemic shunt. Despite the apparent importance of inflammation in driving hepatic encephalopathy in dogs, it is unclear whether inflammation resolves following the successful treatment of liver disease. We hypothesized that haematological and biochemical evidence of inflammation, as gauged by neutrophil, lymphocyte and monocyte concentrations together with C-reactive protein concentrations, would decrease following successful treatment of congenital portosystemic shunts in dogs. One hundred and forty dogs with a congenital portosystemic shunt were enrolled into the study. We found that the proportion of dogs with a monocyte concentration above the reference range was significantly greater in dogs with hepatic encephalopathy at time of initial diagnosis. Importantly, neutrophil and monocyte concentrations significantly decreased following surgical congenital portosystemic shunt attenuation. We also found a significant decrease in C-reactive protein concentrations following surgical attenuation of congenital portosystemic shunts. Our study demonstrates that haematological and biochemical indices of inflammation reduce following successful treatment of the underlying liver disorder

Detecção de encefalopatia hepática mínima através de testes neuropsicológicos e neurofisiológicos e o papel da amônia no seu diagnóstico Minimal hepatic encephalopathy detection by neuropsychological and neurophysiological methods and the role of ammonia for its diagnosis

CONTEXTO: A encefalopatia hepática mínima vem sendo sistematicamente investigada em pacientes com cirrose hepática. Entretanto, existem controvérsias quanto aos melhores métodos, bem como o papel da amônia para seu diagnóstico. OBJETIVO: Avaliar a frequência de encefalopatia hepática mínima diagnosticada através de testes neuropsicológicos e neurofisiológicos em cirróticos, bem como os possíveis fatores de risco para esta condição, incluindo o papel da concentração arterial de amônia em seu diagnóstico. MÉTODOS: Indivíduos com cirrose hepática foram avaliados através do teste de conexão numérica partes A e B (TCN-A e TCN-B) e potencial evocado relacionado a eventos (P300). O diagnóstico de encefalopatia hepática mínima foi feito quando da presença de anormalidade no P300 e em, pelo menos, um dos testes neuropsicológicos. As concentrações arteriais de amônia, a escolaridade e a gravidade da cirrose hepática também foram avaliadas em todos. RESULTADOS: Foram avaliados 48 pacientes cirróticos, com média de idade 50 ± 8 anos, sendo 79% do sexo masculino. As principais causas foram a alcoólica e a viral. O P300 foi anormal em 75% dos casos e o TCN-A e TCN-B anormais em 58% e 65% dos casos, respectivamente. Os resultados do TCN-B foram influenciados pela escolaridade. A frequência de encefalopatia hepática mínima foi de 50%. A concentração arterial de amônia não foi significantemente maior em pacientes com diagnóstico de encefalopatia hepática mínima (195 ± 152 mmol/L versus 148 ± 146 mmol/L; P>0,05). Não houve diferença significante entre os grupos com e sem encefalopatia hepática mínima quanto às demais variáveis estudadas. CONCLUSÃO:A encefalopatia hepática mínima é condição frequente em pacientes com cirrose hepática. A concentração arterial de amônia não parece ter papel importante no seu diagnóstico.<br>CONTEXT: Minimal hepatic encephalopathy has been systematically investigated in cirrhotic patients. Although, there are controversies regarding the best methods as well as the role of ammonia for its diagnosis. OBJECTIVE: To evaluate the frequency of minimal hepatic encephalopathy diagnosed by neuropsychological and neurophysiological methods in cirrhotic patients, as well as possible associated risk factors for this condition, including the role of arterial ammonia concentrations for its diagnosis. METHODS: Cirrhotic patients were evaluated by the number connection test parts A and B (NCT-A and NCT-B), and auditory evoked-related potentials (P300). Minimal hepatic encephalopathy was diagnosed by the presence of abnormal P300 and in unless one of the performed neuropsychologic tests. Arterial ammonia concentration, scholarity and cirrhosis severity accessed by Child-Pugh classification were evaluated in all. RESULTS: Forty-eight cirrhotic patients were evaluated, with median age 50 ± 8 years old, 79% male. The main etiologies were alcoholic and viral. The P300 was abnormal in 75% of cases, while NCT-A and NCT-B were abnormal in 58% and 65%, respectively. The NCT-B results were influenced by scholarity. The minimal hepatic encephalopathy frequency was 50%. Arterial ammonia concentration was not significantly increased in minimal hepatic encephalopathy diagnosed patients (195 ± 152 mmol/L versus 148 ± 146 mmol/L; P>0,05). There was no difference between groups with or without minimal hepatic encephalopathy in the other studied variables. CONCLUSION: Minimal hepatic encephalopathy is a frequent condition in cirrhotic patients. The arterial ammonia concentration does not play a major role in its diagnosis

Mineralocorticoid and glucocorticoid receptors differentially regulate NF-kappaB activity and pro-inflammatory cytokine production in murine BV-2 microglial cells

ABSTRACT:; Microglia, the resident macrophage-like cells in the brain, regulate innate immune responses in the CNS to protect neurons. However, excessive activation of microglia contributes to neurodegenerative diseases. Corticosteroids are potent modulators of inflammation and mediate their effects by binding to mineralocorticoid receptors (MR) and glucocorticoid receptors (GR). Here, the coordinated activities of GR and MR on the modulation of the nuclear factor-κB (NF-κB) pathway in murine BV-2 microglial cells were studied.; BV-2 cells were treated with different corticosteroids in the presence or absence of MR and GR antagonists. The impact of the glucocorticoid-activating enzyme 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) was determined by incubating cells with 11-dehydrocorticosterone, with or without selective inhibitors. Expression of interleukin-6 (IL-6), tumor necrosis factor receptor 2 (TNFR2), and 11β-HSD1 mRNA was analyzed by RT-PCR and IL-6 protein expression by ELISA. NF-κB activation and translocation upon treatment with various corticosteroids were visualized by western blotting, immunofluorescence microscopy, and translocation assays.; GR and MR differentially regulate NF-κB activation and neuroinflammatory parameters in BV-2 cells. By converting inactive 11-dehydrocorticosterone to active corticosterone, 11β-HSD1 essentially modulates the coordinated action of GR and MR. Biphasic effects were observed for 11-dehydrocorticosterone and corticosterone, with an MR-dependent potentiation of IL-6 and tumor necrosis factor-α (TNF-α) expression and NF-κB activation at low/moderate concentrations and a GR-dependent suppression at high concentrations. The respective effects were confirmed using the MR ligand aldosterone and the antagonist spironolactone as well as the GR ligand dexamethasone and the antagonist RU-486. NF-κB activation could be blocked by spironolactone and the inhibitor of NF-κB translocation Cay-10512. Moreover, an increased expression of TNFR2 was observed upon treatment with 11-dehydrocorticosterone and aldosterone, which was reversed by 11β-HSD1 inhibitors and/or spironolactone and Cay-10512.; A tightly coordinated GR and MR activity regulates the NF-κB pathway and the control of inflammatory mediators in microglia cells. The balance of GR and MR activity is locally modulated by the action of 11β-HSD1, which is upregulated by pro-inflammatory mediators and may represent an important feedback mechanism involved in resolution of inflammation