STAT1-dependent signal integration between IFNγ and TLR4 in vascular cells reflect pro-atherogenic responses in human atherosclerosis.

Signal integration between IFNγ and TLRs in immune cells has been associated with the host defense against pathogens and injury, with a predominant role of STAT1. We hypothesize that STAT1-dependent transcriptional changes in vascular cells involved in cross-talk between IFNγ and TLR4, reflect pro-atherogenic responses in human atherosclerosis. Genome-wide investigation identified a set of STAT1-dependent genes that were synergistically affected by interactions between IFNγ and TLR4 in VSMCs. These included the chemokines Cxcl9, Ccl12, Ccl8, Ccrl2, Cxcl10 and Ccl5, adhesion molecules Cd40, Cd74, and antiviral and antibacterial genes Rsad2, Mx1, Oasl1, Gbp5, Nos2, Batf2 and Tnfrsf11a. Among the amplified genes was also Irf8, of which Ccl5 was subsequently identified as a new pro-inflammatory target in VSMCs and ECs. Promoter analysis predicted transcriptional cooperation between STAT1, IRF1, IRF8 and NFκB, with the novel role of IRF8 providing an additional layer to the overall complexity. The synergistic interactions between IFNγ and TLR4 also resulted in increased T-cell migration and impaired aortic contractility in a STAT1-dependent manner. Expression of the chemokines CXCL9 and CXCL10 correlated with STAT1 phosphorylation in vascular cells in plaques from human carotid arteries. Moreover, using data mining of human plaque transcriptomes, expression of a selection of these STAT1-dependent pro-atherogenic genes was found to be increased in coronary artery disease (CAD) and carotid atherosclerosis. Our study provides evidence to suggest that in ECs and VSMCs STAT1 orchestrates a platform for cross-talk between IFNγ and TLR4, and identifies a STAT1-dependent gene signature that reflects a pro-atherogenic state in human atherosclerosis.

Microvascular dysfunction in the course of metabolic syndrome induced by high-fat diet.

BACKGROUND: Metabolic syndrome (MetS) is associated with increased risk of cardiovascular disease (CVD). One important feature underlying the pathophysiology of many types of CVD is microvascular dysfunction. Although components of MetS are themselves CVD risk factors, the risk is increased when the syndrome is considered as one entity. We aimed to characterize microvascular function and some of its influencing factors in the course of MetS development. METHODS: Development of MetS in C57BL/6 mice on a high-fat diet (HFD, 51% of energy from fat) was studied. The initial phase of MetS (I-MetS) was defined as the first 2 weeks of HFD feeding, with the fully developed phase occurring after 8 weeks of HFD. We characterized these phases by assessing changes in adiposity, blood pressure, and microvascular function. All data are presented as mean ± standard error (SEM). Differences between cumulative dose-response curves of myograph experiments were calculated using non-linear regression analysis. In other experiments, comparisons between two groups were made with Student's t-test. Comparisons between more than two groups were made using one-way ANOVA with Tukey post-hoc test. A probability value <0.05 was considered statistically significant. RESULTS: I-MetS mice presented with weight gain, blood pressure elevation, and microvascular dysfunction characterized by augmented vasoconstriction. This finding, contrary to those in mice with fully developed MetS, was not associated with endothelial dysfunction, insulin resistance, or systemic inflammation. In the initial phase, perivascular adipose tissue showed no sign of inflammation and had no influence on the pattern of vasoconstriction. These findings suggest that the onset of hypertension in MetS is strongly influenced by vascular smooth muscle cell dysfunction and independent of important factors known to influence microvascular function and consequently blood pressure levels. CONCLUSION: We identified in I-MetS the occurrence of isolated augmented vasoconstriction along with blood pressure elevation, but not the presence of classical MetS components known to influence microvascular function. These findings increase our understanding of the pathophysiology of CVD risk associated with MetS.

Damage-associated molecular pattern activated Toll-like receptor 4 signalling modulates blood pressure in L-NAME-induced hypertension.

AIMS: Recent publications have shed new light on the role of the adaptive and innate immune system in the pathogenesis of hypertension. However, there are limited data whether receptors of the innate immune system may influence blood pressure. Toll-like receptor 4 (TLR4), a pattern recognition receptor, is a key component of the innate immune system, which is activated by exogenous and endogenous ligands. Hypertension is associated with end-organ damage and thus might lead to the release of damage-associated molecular patterns (DAMPs), which are endogenous activators of TLR4 receptors. The present study aimed to elucidate whether TLR4 signalling is able to modulate vascular contractility in an experimental model of hypertension thus contributing to blood pressure regulation. METHODS AND RESULTS: NG-nitro-l-arginine methyl ester (l-NAME)-induced hypertension was blunted in TLR4(-/-) when compared with wild-type mice. Treatment with l-NAME was associated with a release of DAMPs, leading to reactive oxygen species production of smooth muscle cells in a TLR4-dependent manner. As oxidative stress leads to an impaired function of the NO-sGC-cyclic GMP (cGMP) pathway, we were able to demonstrate that TLR4(-/-) was protected from sGC inactivation. Consequently, arterial contractility was reduced in TLR4(-/-). CONCLUSIONS: Cell damage-associated TLR4 signalling might act as a direct mediator of vascular contractility providing a molecular link between inflammation and hypertension.

[Hemoglobin levels in hemodialysis patients treated with epoetin: a Brazilian experience]. / Variação dos níveis de hemoglobina de pacientes em hemodiálise tratados com eritropoetina: uma experiência brasileira.

OBJECTIVE: Correction of anemia using epoetin decreases morbidity and increases survival and quality of life in end-stage renal disease. Maintaining hemoglobin levels within the range proposed by guidelines has become a major challenge, with hemoglobin cycling affecting more than 90% of patients undergoing hemodialysis. The variability of hemoglobin levels over time was assessed in our patients. METHODS: Data were retrospectively collected on 249 patients undergoing hemodialysis over a 3-year period at seven centers in Brazil. Hemoglobin was measured at least monthly, and target levels were those between 10.5 g/dL and 12.5 g/dL. Patients were grouped into six categories of variability consistently low (<10.5 g/dL), consistently target range (10.5 to 12.5 g/dL), consistently high (>12.5 g/dL), low amplitude fluctuation with low hemoglobin levels, low amplitude fluctuation with high hemoglobin levels and high amplitude fluctuation. None of the patients maintained stable hemoglobin levels for the entire 36-month period. RESULTS: The mean monthly proportion of patients that had hemoglobin levels within the target range was 50% (range, 42% to 61%). Mean levels above the target (30%) were more frequent than those below it (20%). During 6, 12, and 36 months, proportions of patients with consistently low levels of hemoglobin decreased from 3.6% to 0%, from 31.7% to 2.8% for those with consistently high, from 7.6% to 0% for those with low amplitude fluctuation with low hemoglobin levels and from 41.3% to 8.3% for those with low amplitude fluctuation with high hemoglobin levels. However, the proportions of patients with high amplitude fluctuation increased from 21.5% to 88.9%. CONCLUSION: Maintaining hemoglobin levels within the target range is difficult, especially for longer periods of time. Missing the target seems more often due to levels above it, but high-amplitude fluctuations eventually occur in the majority of patients.

Variação dos níveis de hemoglobina de pacientes em hemodiálise tratados com eritropoetina: uma experiência brasileira / Hemoglobin levels in hemodialysis patients treated with epoetin: a Brazilian experience

OBJETIVO: Avaliar a variabilidade dos níveis de hemoglobina (Hb) em pacientes em hemodiálise (HD) tratados com eritropoetina. MÉTODOS: Foram coletados dados retrospectivos de 249 pacientes que estavam em HD e apresentavam, nos três meses anteriores, média de Hb entre 10,5 g/dL e 12,5 g/dL. O período de observação total foi de 36 meses. A cada mês de coleta, classificaram-se os valores de Hb em: < 10,5g/dL, 10,5g/dL< Hb< 12,5g/dL (intervalo alvo), ou Hb >12,5g/dL. Além disto, os pacientes foram divididos em seis categorias de variabilidade da Hb: baixo persistente (<10,5g/dL), alvo persistente (10,5 a 12,5 g/dL), alto persistente (>12,5g/dL), flutuação de baixa amplitude com Hb baixo, flutuações de baixa amplitude com Hb alto e flutuações de alta amplitude. RESULTADOS: Mês a mês, a média da proporção de pacientes com Hb dentro da faixa alvo foi de 50 por cento (variação, 42 por cento a 61 por cento). A proporção de valores de Hb médios acima da faixa alvo (30 por cento) foi mais frequente que a proporção abaixo do alvo (20 por cento). Durante os períodos de seis, 12, e 36 meses, a proporção de pacientes com Hb baixa persistente se reduziu de 3,6 por cento para 0 por cento; de 31,7 por cento para 2,8 por cento naqueles com Hb alta persistente; de 7,6 por cento para 0 por cento naqueles com baixa amplitude com Hb baixo; e de 41,3 por cento para 8,3 por cento nos pacientes com baixa amplitude com Hb alto. Entretanto, houve aumento na proporção de pacientes (de 21,5 por cento a 88,9 por cento) com alta amplitude de Hb. Portanto, à medida que o tempo de observação se alongou observou-se maior variabilidade dos valores de hemoglobina. Nenhum paciente manteve os níveis de Hb dentro do alvo durante todo o período do estudo. CONCLUSÃO: A manutenção da Hb dentro da faixa alvo é difícil, especialmente em períodos longos e a variabilidade ocorre mais frequentemente para valores mais elevados de Hb.

OBJECTIVE: Correction of anemia using epoetin decreases morbidity and increases survival and quality of life in end-stage renal disease. Maintaining hemoglobin levels within the range proposed by guidelines has become a major challenge, with hemoglobin cycling affecting more than 90 percent of patients undergoing hemodialysis. The variability of hemoglobin levels over time was assessed in our patients. METHODS: Data were retrospectively collected on 249 patients undergoing hemodialysis over a 3-year period at seven centers in Brazil. Hemoglobin was measured at least monthly, and target levels were those between 10.5 g/dL and 12.5 g/dL. Patients were grouped into six categories of variability consistently low (<10.5g/dL), consistently target range (10.5 to 12.5 g/dL), consistently high (>12.5g/dL), low amplitude fluctuation with low hemoglobin levels, low amplitude fluctuation with high hemoglobin levels and high amplitude fluctuation. None of the patients maintained stable hemoglobin levels for the entire 36-month period. RESULTS: The mean monthly proportion of patients that had hemoglobin levels within the target range was 50 percent (range, 42 percent to 61 percent). Mean levels above the target (30 percent) were more frequent than those below it (20 percent). During 6, 12, and 36 months, proportions of patients with consistently low levels of hemoglobin decreased from 3.6 percent to 0 percent, from 31.7 percent to 2.8 percent for those with consistently high, from 7.6 percent to 0 percent for those with low amplitude fluctuation with low hemoglobin levels and from 41.3 percent to 8.3 percent for those with low amplitude fluctuation with high hemoglobin levels. However, the proportions of patients with high amplitude fluctuation increased from 21.5 percent to 88.9 percent. CONCLUSION: Maintaining hemoglobin levels within the target range is difficult, especially for longer periods of time. Missing the target seems more often due to ...