Relationship between different subpopulations of circulating CD4+ T lymphocytes and microvascular or systemic oxidative stress in humans.

BACKGROUND AND OBJECTIVE: Different components of the immune system, including innate and adaptive immunity (T effector lymphocytes and T regulatory lymphocytes - TREGs) may be involved in the development of hypertension, vascular injury and inflammation. However, no data are presently available in humans about possible relationships between T-lymphocyte subtypes and microvascular oxidative stress. Our objective was to investigate possible relationships between T-lymphocyte subtypes and systemic and microvascular oxidative stress in a population of normotensive subjects and hypertensive patients. PATIENTS AND METHODS: In the present study we enrolled 24 normotensive subjects and 12 hypertensive patients undergoing an elective surgical intervention. No sign of local or systemic inflammation was present. All patients underwent a biopsy of subcutaneous fat during surgery. A peripheral blood sample was obtained before surgery for assessment of T lymphocyte subpopulations by flow cytometry and circulating indices of oxidative stress. RESULTS: A significant direct correlation was observed between Th1 lymphocytes and reactive oxygen species (ROS) production (mainly in microvessels). Additionally, significant inverse correlations were observed between ROS and total TREGs, or TREGs subtypes. Significant correlations were detected between circulating indices of oxidative stress/inflammation and indices of microvascular morphology/Th1 and Th17 lymphocytes. In addition, a significant inverse correlation was detected between TREGs in subcutaneous small vessels and C reactive protein. CONCLUSIONS: Our data suggest that TREG lymphocytes may be protective against microvascular damage, probably because of their anti-oxidant properties, while Th1-Th17 lymphocytes seem to exert an opposite effect, confirming an involvement of adaptive immune system in microvascular damage.

Effect of antihypertensive treatments on insulin signalling in lympho-monocytes of essential hypertensive patients: a pilot study.

It was previously demonstrated that metabolic syndrome in humans is associated with an impairment of insulin signalling in circulating mononuclear cells. At least in animal models of hypertension, angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARB) may correct alterations of insulin signalling in the skeletal muscle. In the first study, we investigated the effects of a 3-month treatment with an ARB with additional PPARγ agonist activity, telmisartan, or with a dihydropyridine calcium channel blocker, nifedipine, on insulin signalling in patients with mild-moderate essential hypertension. Insulin signalling was evaluated in mononuclear cells by isolating them through Ficoll-Paque density gradient centrifugation and protein analysis by Western Blot. An increased expression of mTOR and of phosphorylated (active) mTOR (p-mTOR) was observed in patients treated with telmisartan, but not in those treated with nifedipine, while both treatments increased the cellular expression of glucose transporter type 4 (GLUT-4). We also investigated the effects of antihypertensive treatment with two drug combinations on insulin signalling and oxidative stress. Twenty essential hypertensive patients were included in the study and treated for 4 weeks with lercanidipine. Then they were treated for 6 months with lercanidipine + enalapril or lercanidipine + hydrochlorothiazide. An increased expression of insulin receptor, GLUT-4 and an increased activation of p70S6K1 were observed during treatment with lercanidipine + enalapril but not with lercanidipine + hydrochlorothiazide. In conclusion, telmisartan and nifedipine are both effective in improving insulin signalling in human hypertension; however, telmisartan seems to have broader effects. The combination treatment lercanidipine + enalapril seems to be more effective than lercanidipine + hydrochlorothiazide in activating insulin signalling in human lympho-monocytes.

Search for atoxic cereals: a single blind, cross-over study on the safety of a single dose of Triticum monococcum, in patients with celiac disease.

BACKGROUND: Cereals of baking quality with absent or reduced toxicity are actively sought as alternative therapy to a gluten-free diet (GFD) for patients with coeliac disease (CD). Triticum monococcum, an ancient wheat, is a potential candidate having no toxicity in in-vitro and ex-vivo studies. The aim of our study was to investigate on the safety of administration of a single dose of gluten of Tm in patients with CD on GFD. METHODS: We performed a single blind, cross-over study involving 12 CD patients who had been on a GFD for at least 12 months, challenged on day 0, 14 and 28 with a single fixed dose of 2.5 grams of the following (random order): Tm, rice (as reference atoxic protein) and Amygluten (as reference toxic protein) dispersed in a gluten-free pudding. The primary end-point of the study was the change in intestinal permeability, as assessed by changes in the urinary lactulose/rhamnose ratio (L/R ratio) measured by High Pressure Liquid Chromatography. We also assessed the occurrence of adverse gastrointestinal events, graded for intensity and duration according to the WHO scale. Variables were expressed as mean ± SD; paired t-test and χ² test were used as appropriate. RESULTS: The urinary L/R ratio did not change significantly upon challenge with the 3 cereals, and was 0.055 ± 0.026 for Tm Vs 0.058 ± 0.035 for rice (p = 0.6736) and Vs 0.063 ± 0.054 with Amygluten (p = 0.6071). Adverse gastrointestinal events were 8 for Tm, Vs 11 for rice (p = 0.6321) and Vs 31 for Amygluten p = 0.0016), and, in all cases events were graded as "mild" or "moderate" with TM and rice, and as "severe" or "disabling" in 4 cases during Amygluten. CONCLUSIONS: No definite conclusion can be drawn on the safety of Tm, based on no change in urinary L/R because even Amygluten, a toxic wheat protein, did not cause a significant change in urinary L/R indicating low sensitivity of this methodology in studies on acute toxicity. Tm was, however, well tolerated by all patients providing the rationale for further investigation on the safety of this cereal for CD patients. TRIAL REGISTRATION: EudraCT-AIFA n2008-000697-20.

Circulating endothelial progenitor cells, microvascular density and fibrosis in obesity before and after bariatric surgery.

It is not known whether, in obesity, the capillary density or the number of circulating endothelial progenitor cells (EPCs) are reduced, or whether fibrosis of small vessels is also present. In addition, possible effects of weight reduction on these parameters have never been evaluated. Therefore, we investigated EPCs and capillary density in 25 patients with severe obesity, all submitted to bariatric surgery, and in 18 normotensive lean subjects and 12 hypertensive lean patients as controls. All patients underwent a biopsy of subcutaneous fat during bariatric surgery. In five patients, a second biopsy was obtained after consistent weight loss, about 1 year later, during a surgical intervention for abdominoplasty. EPCs and capillary density were reduced in obesity, and EPCs were significantly increased after weight reduction. Vascular collagen content was clearly increased in obese patients. No significant difference in vascular collagen was observed between normotensive obese patients and hypertensive obese patients. After pronounced weight reduction, collagen content was nearly normalized. No difference in stress-strain relation was observed among groups or before and after weight loss. In conclusion, our data suggest that microvascular rarefaction occurs in obesity. EPCs were significantly reduced in obese patients. Pronounced weight loss induced by bariatric surgery seems to induce a significant improvement of EPC number, but not of capillary rarefaction. A pronounced fibrosis of subcutaneous small resistance arteries is present in obese patients, regardless of the presence of increased blood pressure values. Consistent weight loss induced by bariatric surgery may induce an almost complete regression of microvascular fibrosis.

Relationship Between Different Subpopulations of Circulating CD4+ T-lymphocytes and Microvascular Structural Alterations in Humans.

BACKGROUND: Different components of the immune system, including innate and adaptive immunity (T-effector lymphocytes and T-regulatory lymphocytes-TREGs) may be involved in the development of hypertension. In addition, it was demonstrated in animal models that TREGs may prevent angiotensin II-induced hypertension and vascular injury/inflammation. However, no data are presently available in humans about possible relationships between T-lymphocyte subtypes and microvascular structural alterations. METHODS: For this purpose, in the present study, we enrolled 24 normotensive subjects and 12 hypertensive patients undergoing an elective surgical intervention. No sign of local or systemic inflammation was present. All patients underwent a biopsy of subcutaneous fat during surgery. Subcutaneous small resistance arteries were dissected and mounted on a wire myograph and the media to lumen ratio (M/L) was calculated. In addition, retinal arteriolar structure was evaluated noninvasively by scanning laser Doppler flowmetry. Capillary density in the nailfold, dorsum of the finger, and forearm were evaluated by videomicroscopy. A peripheral blood sample was obtained before surgery for assessment of T-lymphocyte subpopulations by flow cytometry. RESULTS: Significant negative correlations were observed between indices of microvascular structure (M/L of subcutaneous small arteries and wall to lumen ratio of retinal arterioles) and circulating TREG lymphocytes. A direct correlation was observed between M/L of subcutaneous small arteries and circulating Th17 lymphocytes. In addition, total capillary density was correlated with a TREG effector memory subpopulation. CONCLUSION: Our data suggest that some lymphocyte subpopulations may be related to microvascular remodeling, confirming previous animal data, and opening therapeutic possibilities.

Immune mechanisms in hypertension.

Low grade inflammation may have a key role in the pathogenesis of hypertension and cardiovascular disease. Several studies showed that both innate and adaptive immune systems may be involved, being T cells the most important players. Particularly, the balance between Th1 effector lymphocytes and Treg lymphocytes may be crucial for blood pressure elevation and related organ damage development. In the presence of a mild elevation of blood pressure, neo-antigens are produced. Activated Th1 cells may then contribute to the persistent elevation of blood pressure by affecting vasculature, kidney and perivascular fat. On the other hand, Tregs represent a lymphocyte subpopulation with an anti-inflammatory role, being their activity crucial for the maintenance of cardiovascular homeostasis. Indeed, Tregs were demonstrated to be able to protect from blood pressure elevation and from the development of organ damage, including micro and macrovascular alterations, in different animal models of genetic or experimental hypertension. In the vasculature, inflammation leads to vascular remodeling through cytokine activity, smooth muscle cell proliferation and oxidative stress. It is also known that a consistent part of ischemia-reperfusion-induced acute kidney injury is mediated by inflammatory infiltration and that Treg cell infusion have a protective role. Also the central nervous system has an important role in the maintenance of cardiovascular homeostasis. In conclusion, hypertension development involves chronic inflammatory process. Knowledge of cellular and molecular players in the progression of hypertension has dramatically improved in the last decade, by assessing the central role of innate and adaptive immunity cells and proinflammatory cytokines driving the development of target organ damage. The new concept of role of immunity, especially implicating T lymphocytes, will eventually allow discovery of new therapeutic targets that may improve outcomes in hypertension and cardiovascular or renal disease in humans and uncover an entirely novel approach in the treatment of hypertension and vascular disease.

Effects of a long-term treatment with aliskiren or ramipril on structural alterations of subcutaneous small-resistance arteries of diabetic hypertensive patients.

Structural alterations of subcutaneous small-resistance arteries are associated with a worse clinical prognosis in hypertension and non-insulin-dependent diabetes mellitus. The effects of the direct renin inhibitor aliskiren on microvascular structure were never previously evaluated. Therefore, we investigated the effects of aliskiren in comparison with those of an extensively used angiotensin-converting enzyme inhibitor, ramipril, on peripheral subcutaneous small-resistance artery morphology, retinal arteriolar structure, and capillary density in a population of patients with non-insulin-dependent diabetes mellitus. Sixteen patients with mild essential hypertension and with a previous diagnosis of non-insulin-dependent diabetes mellitus were included in the study. Patients were then randomized to 1 of the 2 active treatments (aliskiren 150 mg once daily, n=9; or ramipril 5 mg once daily, n=7). Each patient underwent a biopsy of the subcutaneous fat from the gluteal region, an evaluation of retinal artery morphology (scanning laser Doppler flowmetry), and capillary density (capillaroscopy), at baseline and after 1 year of treatment. Subcutaneous small arteries were dissected and mounted on a pressurized micromyograph, and the media-to-lumen ratio was evaluated. A similar office blood pressure-lowering effect and a similar reduction of the wall-to-lumen ratio of retinal arterioles were observed with the 2 drugs. Aliskiren significantly reduced media-to-lumen ratio of subcutaneous small-resistance arteries, whereas ramipril-induced reduction of media to lumen ratio was not statistically significant. No relevant effect on capillary density was observed. In conclusion, treatment with aliskiren or ramipril was associated with a correction of microvascular structural alterations in patients with non-insulin-dependent diabetes mellitus.

Total lymphocyte count and in-hospital mortality in older persons with multimorbidity.

BACKGROUND AND AIMS: Low total lymphocyte count (TLC) has been found to be a poor prognostic factor in adults affected by heart diseases, malignancy, and renal failure. The aims of this study were to verify if a low TLC was associated with in-hospital mortality in older persons and to evaluate whether this association was independent of the presence of multiple co-existing diseases (multimorbidity). METHODS: The authors carried out a cross-section analysis of data of 65+ years old patients (n=596) admitted to a Geriatric Unit in Northern Italy. TLC, total white blood cell count (WBC) and serum albumin were assayed the day after admission. The presence and severity of diseases were evaluated with the Geriatric Index of Comorbidity (GIC). Other covariates included age, gender, cigarette smoking, cognition (Mini-Mental State Examination) and function (Activities of Daily Living). Logistic regression models were created to study factors affecting in-hospital death. RESULTS: TLC was inversely correlated with both age and multimorbidity. Patients in the lowest tertile of TLC had the highest association with death during hospitalization (OR 6.1, 95% CI 1.1-33.6) independently of multimorbidity and all the other covariates. Stratifying the sample by degree of multimorbidity, this association was clearest in patients with the least severe multimorbidity (GIC