Sympathetic Enhancement of Memory T-Cell Homing and Hypertension Sensitization.

RATIONALE: Effector memory T lymphocytes (TEM cells) exacerbate hypertension in response to repeated hypertensive stimuli. These cells reside in the bone marrow for prolonged periods and can be reactivated on reexposure to the hypertensive stimulus. OBJECTIVE: Because hypertension is associated with increased sympathetic outflow to the bone marrow, we hypothesized that sympathetic nerves regulate accumulation and reactivation of bone marrow-residing hypertension-specific TEM cells. METHODS AND RESULTS: Using unilateral superior cervical ganglionectomy in wild-type C57BL/6 mice, we showed that sympathetic nerves create a bone marrow environment that supports residence of hypertension-specific CD8+ T cells. These cells, defined by their proliferative response on coculture with dendritic cells from Ang (angiotensin) II-infused mice, were reduced in denervated compared with innervated bone of Ang II-infused mice. Adoptively transferred CD8+ T cells from Ang II-infused mice preferentially homed to innervated compared with denervated bone. In contrast, ovalbumin responsive T cells from OT-I mice did not exhibit this preferential homing. Increasing superior cervical ganglion activity by activating Gq-coupled designer receptor exclusively activated by designer drug augmented CD8+ TEM bone marrow accumulation. Adoptive transfer studies using mice lacking ß2AR (ß2 adrenergic receptors) indicate that ß2AR in the bone marrow niche, rather than T-cell ß2AR is critical for TEM cell homing. Inhibition of global sympathetic outflow using Gi-coupled DREADD (designer receptor exclusively activated by designer drug) injected into the rostral ventrolateral medulla or treatment with a ß2AR antagonist reduced hypertension-specific CD8+ TEM cells in the bone marrow and reduced the hypertensive response to a subsequent response to low dose Ang II. CONCLUSIONS: Sympathetic nerves contribute to the homing and survival of hypertension-specific TEM cells in the bone marrow after they are formed in hypertension. Inhibition of sympathetic nerve activity and ß2AR blockade reduces these cells and prevents the blood pressure elevation and renal inflammation on reexposure to hypertension stimuli.

Excessive cholecalciferol supplementation increases kidney dysfunction associated with intrarenal artery calcification in obese insulin-resistant mice.

Diabetes mellitus accelerates vascular calcification (VC) and increases the risk of end-stage renal disease (ESRD). Nevertheless, the impact of VC in renal disease progression in type 2 diabetes mellitus (T2DM) is poorly understood. We addressed the effect of VC and mechanisms involved in renal dysfunction in a murine model of insulin resistance and obesity (ob/ob), comparing with their healthy littermates (C57BL/6). We analyzed VC and renal function in both mouse strains after challenging them with Vitamin D3 (VitD3). Although VitD3 similarly increased serum calcium and induced bone disease in both strains, 24-hour urine volume and creatinine pronouncedly decreased only in ob/ob mice. Moreover, ob/ob increased urinary albumin/creatinine ratio (ACR), indicating kidney dysfunction. In parallel, ob/ob developed extensive intrarenal VC after VitD3. Coincidently with increased intrarenal vascular mineralization, our results demonstrated that Bone Morphogenetic Protein-2 (BMP-2) was highly expressed in these arteries exclusively in ob/ob. These data depict a greater susceptibility of ob/ob mice to develop renal disease after VitD3 in comparison to paired C57BL/6. In conclusion, this study unfolds novel mechanisms of progressive renal dysfunction in diabetes mellitus (DM) after VitD3 in vivo associated with increased intrarenal VC and highlights possible harmful effects of long-term supplementation of VitD3 in this population.

Central EP3 (E Prostanoid 3) Receptors Mediate Salt-Sensitive Hypertension and Immune Activation.

We recently identified a pathway underlying immune activation in hypertension. Proteins oxidatively modified by reactive isoLG (isolevuglandin) accumulate in dendritic cells (DCs). PGE2 (Prostaglandin E2) has been implicated in the inflammation associated with hypertension. We hypothesized that PGE2 via its EP (E prostanoid) 3 receptor contributes to DC activation in hypertension. EP3-/- mice and wild-type littermates were exposed to sequential hypertensive stimuli involving an initial 2-week exposure to the nitric oxide synthase inhibitor Nω-nitro-L-arginine methyl ester hydrochloride in drinking water, followed by a 2-week washout period, and a subsequent 4% high-salt diet for 3 weeks. In wild-type mice, this protocol increased systolic pressure from 123±2 to 148±8 mm Hg (P<0.05). This was associated with marked renal inflammation and a striking accumulation of isoLG adducts in splenic DCs. However, the increases in blood pressure, renal T-cell infiltration, and DC isoLG formation were completely prevented in EP3-/- mice. Similar protective effects were also observed in wild-type mice that received intracerebroventricular injection of a lentiviral vector encoding shRNA targeting the EP3 receptor. Further, in vitro experiments indicated that PGE2 also acts directly on DCs via its EP1 receptors to stimulate intracellular isoLG formation. Together, these findings provide new insight into how EP receptors in both the central nervous system and peripherally on DCs promote inflammation in salt-induced hypertension.

NOX5 as a therapeutic target in cerebral ischemic injury.

In this issue of the JCI, Casas et al. define a previously unknown role of the NADPH oxidase catalytic subunit NOX5 in cerebral infarction. Using a mouse expressing human NOX5 in the endothelium, the investigators show that NOX5 is activated and plays a deleterious role in promoting edema, infarction, and ultimately, worsened neurological function following cerebral ischemia. They provide evidence that this is due to the breakdown of the blood-brain barrier (BBB) and that a unique pharmacological inhibitor of NOX5, ML090, if given early, around the time of reoxygenation, can maintain BBB integrity. Future studies of NOX5 inhibition in humans, particularly in the setting of thrombolysis, are warranted.

The Effects of Yerba Maté (Ilex Paraguariensis) consumption on IL-1, IL-6, TNF-α and IL-10 production by bone marrow cells in wistar rats fed a high-fat diet.

An excessive consumption of a high-fat diet (HFD) results in becoming overweight or obese, which triggers a chronic inflammatory condition that is associated with a high white blood cell count. Because of the potential for yerba maté (Ilex paraguariensis) (YM) to impact obesity, this study aimed to investigate the effects of YM consumption on the hematological response and on the production of interleukin (IL)-1α, IL-6, tumor necrosis factor (TNF)-α, and IL-10 by bone marrow cells from Wistar rats fed a HFD. Male Wistar rats were fed a control (CON) or HFD diet for twelve weeks. At the end of this period, the rats received YM (1 g/kg/day body weight) for 4 weeks. After euthanasia, hemograms and myelograms were evaluated, while the bone marrow cells were cultured in the presence or absence of lipopolysaccharide (LPS) to evaluate the production of IL-1α, IL-6, TNF-α, and IL-10. The consumption of YM reduced the body weight, the body adiposity, and the cholesterol levels in HFD-fed rats. Bone marrow cells from the HFD group produced more IL-1α, IL-6, and TNF-α, and less IL-10, when compared to cells from the control group, and YM consumption reduced the IL-1α, IL-6, and TNF-α production by the cells. However, cells from the HFD rats that were stimulated with LPS increased their IL-1α, IL-6, and TNF-α production, but YM consumption did not change this result. In summary, the consumption of YM affects the production of IL-1α, IL-6, and TNF-α by bone marrow cells, promotes weight loss, decreases the number of white blood cells, and significantly improves serum cholesterol level in HFD-fed rats. However, the bone marrow cells from the HFD+YM-fed rats challenged with LPS did not show improvement in the inflammatory response compared to the cells from animals fed only a HFD that were also challenged with LPS.

Vascular calcification: pathophysiology and clinical implications.

Vascular calcification in coronary artery disease is gaining importance, both in scientific research and in clinical and imaging applications. The calcified plaque is considered the most relevant form of atherosclerosis within the coronary artery tree and is frequently a challenge for percutaneous intervention. Recent studies showed that plaque calcification is dynamic and is strictly related to the degree of vascular inflammation. Several inflammatory factors produced during the different phases of atherosclerosis induce the expression and activation of osteoblastic cells located within the arterial wall, which, in turn, promote the deposit of calcium. The vascular smooth muscle cells have an extraordinary capacity to undergo osteoblastic phenotypical differentiation. There is no doubt that the role of these factors, as well as the elements of genomics and proteomics, could be a vital strategic point in prevention and treatment. Within this context, we conducted an updating review on coronary calcification focused on pathophysiology, experimental models, and clinical implications of vascular calcification.

Calcificação vascular: fisiopatologia e implicações clínicas / Vascular calcification: pathophysiology and clinical implications

A calcificação vascular na doença arterial coronária está ganhando importância, tanto em pesquisas científicas como em aplicações clínicas e de imagem. A placa calcificada é considerada a forma mais relevante de aterosclerose dentro da árvore arterial coronária e frequentemente apresenta um desafio para a intervenção percutânea. Estudos recentes têm demonstrado que a calcificação da placa é dinâmica e está estreitamente ligada ao grau de inflamação vascular. Vários fatores inflamatórios, produzidos durante as diferentes fases da aterosclerose, induzem a expressão e ativação de células osteoblásticas localizadas na parede arterial, que, por sua vez, promovem a deposição de cálcio. As células do músculo liso vascular possuem uma capacidade extraordinária de sofrer diferenciação fenotípica osteoblástica. Não há dúvida de que o papel desses fatores, bem como os elementos de genômica e proteômica, poderia ser um ponto estratégico fundamental na prevenção e no tratamento. Neste contexto, realizamos uma atualização sobre a calcificação coronária, com foco em fisiopatologia, modelos experimentais e implicações clínicas da calcificação vascular.

Vascular calcification in coronary artery disease is gaining importance, both in scientific research and in clinical and imaging applications. The calcified plaque is considered the most relevant form of atherosclerosis within the coronary artery tree and is frequently a challenge for percutaneous intervention. Recent studies showed that plaque calcification is dynamic and is strictly related to the degree of vascular inflammation. Several inflammatory factors produced during the different phases of atherosclerosis induce the expression and activation of osteoblastic cells located within the arterial wall, which, in turn, promote the deposit of calcium. The vascular smooth muscle cells have an extraordinary capacity to undergo osteoblastic phenotypical differentiation. There is no doubt that the role of these factors, as well as the elements of genomics and proteomics, could be a vital strategic point in prevention and treatment. Within this context, we conducted an updating review on coronary calcification focused on pathophysiology, experimental models, and clinical implications of vascular calcification.

A high-fat diet increases interleukin-3 and granulocyte colony-stimulating factor production by bone marrow cells and triggers bone marrow hyperplasia and neutrophilia in Wistar rats.

It is well established that the excessive consumption of a high-fat diet (HFD) results in overweight, obesity and an increase in leptin concentrations, which triggers a chronic inflammatory condition that is associated with a high white blood cell count. Two-month-old male Wistar rats were fed a control (CON) diet or an HFD for 12 weeks. After this period, hemogram, myelogram and biochemical parameters were evaluated along with the cell cycle and the percentage of CD34(+) cells in the bone marrow as well as cell proliferation and differentiation assays and the production of stem cell factor, interleukin 3 (IL-3), granulocyte colony-stimulating factor (G-CSF) and granulocyte macrophage colony-stimulating factor (GM-CSF). The HFD animals exhibited leukocytosis and neutrophilia with increased C-reactive protein, leptin, cholesterol and triglyceride concentrations. In the HFD group, the bone marrow revealed myeloid hyperplasia, especially of the granulocytic compartment with a higher percentage of CD34(+) cells and a higher percentage of cells in the G2/S/M cell cycle phases. In addition, the HFD bone marrow cells had a higher capacity to proliferate and differentiate into granulocytic cells in an in vitro system and a higher capacity to produce IL-3 and G-CSF. These data led us to infer that the HFD induces leukocytosis and neutrophilia suggesting alterations in hematopoiesis system modulation.

A high-fat diet increases IL-1, IL-6, and TNF-α production by increasing NF-κB and attenuating PPAR-γ expression in bone marrow mesenchymal stem cells.

It is well established that a high-fat diet (HFD) can lead to overweight and ultimately to obesity, as well as promoting low-grade chronic inflammation associated with increased levels of such mediators as TNF-α, IL-1, and IL-6. Bone marrow mesenchymal stem cells (MSCs), which are involved in hematopoietic niches and microenvironments, can be affected by these cytokines, resulting in induction of NF-κB and inhibition of PPAR-γ. Because this phenomenon could ultimately lead to suppression of bone marrow adipogenesis, we set out to investigate the effect of an HFD on the expression of PPAR-γ and NF-κB, as well as the production of IL-1, IL-6, and TNF-α in MSCs. Two-month-old male Wistar rats were fed a HFD diet and evaluated by means of leukograms and myelograms along with blood total cholesterol, triglyceride, and C-reactive protein levels. MSCs were isolated, and PPAR-γ and NF-κB were quantified, as well as IL-1, IL-6, and TNF-α production. Animals that were fed a HFD showed higher levels of blood total cholesterol, triglycerides, and C-reactive protein with leukocytosis and bone marrow hyperplasia. MSCs from HFD animals showed increased production of IL-1, IL-6, and TNF-α and increased NF-κB and reduced PPAR-γ expression. Therefore, ingestion of an HFD induces alterations in MSCs that may influence modulation of hematopoiesis.