Prognostic significance of the wall to lumen ratio of retinal arterioles evaluated by adaptive optics.

OBJECTIVE: Microvascular structural alterations may be considered an important form of hypertension-mediated organ damage. An increased media-to-lumen ratio of subcutaneous small arteries evaluated with locally invasive techniques (micromyography) predicts the development of cardiovascular (CV) events. However, it is not known whether retinal arteriole structural alterations evaluated with a noninvasive approach (Adaptive Optics) may have a prognostic significance. DESIGN AND METHODS: Two-hundred and thirty-seven subjects (mean age 58.7 ± 16.1 years, age range 13-89 years; 116 males) were included in the study: 65 normotensive subjects (27.4 %) and 172 patients with essential hypertension or primary aldosteronism (72.6 %). All subjects underwent a non-invasive evaluation of retinal arteriolar wall-to-lumen ratio (WLR) by Adaptive Optics. Subjects were re-evaluated after an average follow-up time of 4.55 years in order to assess the occurrence of clinical events (non CV and/or CV death or events). RESULTS: Fifty-four events occurred in the study population:26 were cardio-cerebrovascular events (ischemic or hemorragic stroke, atrial fibrillation, heart failure, coronary artery disease, peripheral artery disease, cardiac valvular disease) while the remaining were deaths for any cause, or neoplastic diseases. Subjects with events were older and had a WLR of retinal arterioles significantly greater than those without events. The event-free survival was significantly worse in those with a baseline WLR above the median value of the population (0.28) according to Kaplan-Mayer survival curves and multivariate analysis (Cox's proportional hazard model). The evidence was confirmed after restricting the analysis to CV events. CONCLUSIONS: Structural alterations of retinal arterioles evaluated by Adaptive Optics may predict total and CV events.

Skin capillary alterations in patients with acute SarsCoV2 infection.

BACKGROUND: Acute SarsCov2 infection is associated with endothelial dysfunction and 'endothelitis', which might explain systemic microvascular impairment. The presence of endothelial damage may promote vasoconstriction with organ ischemia, inflammation, tissue oedema and a procoagulant state resulting in an increase in the incidence of cardiovascular and cerebrovascular events. Microvascular thrombosis has been demonstrated in postmortem autopsy of COVID-19 patients; however, few data are available about skin capillary alterations in these patients. MATERIALS AND METHODS: We evaluated skin microvascular alteration in 22 patients admitted to our hospital with SarsCov2 infection. Capillary density was evaluated by capillaroscopy in the nailfold and the dorsum of the finger in the acute phase of the disease. Capillaroscopy was repeated after 3 months (recovery phase). In addition, blood chemistry parameters and inflammatory markers were obtained during acute infection and at the recovery after 3 months. RESULTS: Patients with COVID-19 showed skin microvascular complications, such as thrombosis, microhaemorrhages and neoangiogenesis, which were not detected after 3 months from the discharge. A significant reduction of capillary density in the dorsum was observed after 3 months from the acute infection (97.2 ±â€Š5.3 vs. 75.81 ±â€Š3.9 n/mm 2P  < 0.05). A significant inverse correlation between C-reactive protein and capillary density was observed in patients with acute SarsCov2 infection ( r  = 0.44, P  < 0.05). Conversely a direct correlation between capillary density during the acute phase and lymphocyte number was detected ( r  = 0.49, P  < 0.05). CONCLUSION: This is the first in-vivo evidence of skin capillary thrombosis, microhaemorrhages and angiogenesis in patients with acute SarsCov2 infection, which disappeared after 3 months, supporting the presence of endothelial dysfunction and inflammation. Capillary alterations might reflect systemic vascular effects of viral infection.

Microvascular Density and Circulating Endothelial Progenitor Cells Before and After Treatment with Incretin Mimetics in Diabetic Patients.

INTRODUCTION: Glucagon-like peptide 1-receptor agonists (incretin mimetics) and dipeptidyl peptidase-4 inhibitors (incretin enhancers) have been recently introduced in the treatment of diabetes mellitus. In particular, incretin mimetics seems to have ancillary antioxidant/antinflammatory properties that might be involved in endothelial protection. AIM: To investigate the effect of incretin mimetic therapy (liraglutide, exenatide) given to 11 patients with type 2 diabetes mellitus, on circulating endothelial progenitor cells (EPCs) (bone marrow-derived cells possibly participating in neovascularization and endothelial protection and repair) and capillary density. METHODS: Four diabetic patients were treated with exenatide (5 µg twice daily for 4 weeks and then 10 µg twice daily for 3 weeks) and 7 with liraglutide (0.6 mg per day for 1 week and then 1.2 mg per day for 3 weeks). Peripheral venous blood samples were obtained before treatment (basal) and after 4 week in patients treated with liraglutide, and after 4 and 7 weeks in patients treated with exenatide, since drug titration is usually longer. EPCs were evaluated by flow cytometry as CD34+/KDR+ cells. Capillary density was evaluated by videomicroscopy, before and after venous congestion, in the dorsum of the 4th finger. RESULTS: Patients treated with liraglutide (6 males 1 female, age 54 ± 12 years) showed a decrease in body mass index and blood pressure during treatment, while patients treated with exenatide (3 males 1 female, age 57 ± 6 years) did not show any relevant change. EPCs were significantly increased after treatment with exenatide, but not after treatment with liraglutide. Capillary density was slightly increased only after 4 weeks of treatment with exenatide, however the increase was no longer present at the final evaluation. CONCLUSIONS: Treatment with exenatide, but not with liraglutide, was able to increase the number of circulating EPCs, possibly through an antioxidative/antiinflammatory effect.

Decreased circulating T regulatory lymphocytes in obese patients undergoing bariatric surgery.

OBJECTIVE: It has been previously demonstrated that T lymphocytes may be involved in the development of hypertension and microvascular remodeling, and that circulating T effector lymphocytes may be increased in hypertension. In particular, Th1 and Th 17 lymphocytes may contribute to the progression of hypertension and microvascular damage while T-regulatory (Treg) lymphocytes seem to be protective in this regard. However, no data is available about patients with severe obesity, in which pronounced microvascular alterations were observed. DESIGN AND METHODS: We have investigated 32 severely obese patients undergoing bariatric surgery, as well as 24 normotensive lean subjects and 12 hypertensive lean subjects undergoing an elective surgical intervention. A peripheral blood sample was obtained before surgery for assessment of CD4+ T lymphocyte subpopulations. Lymphocyte phenotype was evaluated by flow cytometry in order to assess T-effector and Treg lymphocytes. RESULTS: A marked reduction of several Treg subpopulations was observed in obese patients compared with controls, together with an increased in CD4+ effector memory T-effector cells. CONCLUSION: In severely obese patients, Treg lymphocytes are clearly reduced and CD4+ effector memory cells are increased. It may be hypothesized that they might contribute to the development of marked microvascular alterations previously observed in these patients.

Changes in extracellular matrix in subcutaneous small resistance arteries of patients with essential hypertension.

BACKGROUND: In the development of hypertensive microvascular remodeling, a relevant role may be played by changes in extracellular matrix proteins. Aim of this study was the to evaluate some extracellular matrix components within the tunica media of subcutaneous small arteries in 9 normotensive subjects and 12 essential hypertensive patients, submitted to a biopsy of subcutaneous fat from the gluteal or the anterior abdominal region. PATIENTS AND METHODS: Subcutaneous small resistance arteries were dissected and mounted on an isometric myograph, and the tunica media to internal lumen ratio was measured. In addition, fibronectin, laminin, transforming growth factor-beta-1 (TGF-ß1) and emilin-1 contents within the tunica media were evaluated by immunofluorescence and relative immunomorphometrical analysis (immunopositivity % of area). The total collagen content and collagen subtypes within the tunica media were evaluated using both Sirius red staining (under polarized light) and immunofluorescence assay. RESULTS: Normotensive controls had less total and type III collagen in respect with hypertensive patients. Fibronectin and TGF-ß1 tunica media content was significantly greater in essential hypertensive patients, compared with normotensive controls, while laminin and emilin-1 tunica media content was lesser in essential hypertensive patients, compared with normotensive controls. A significant correlation was observed between fibronectin tunica media content and media to lumen ratio. CONCLUSIONS: Our results indicate that, in small resistance arteries of patients with essential hypertension, a relevant fibrosis may be detected; fibronectin and TGF-ß1 tunica media content is increased, while laminin and emilin-1 content is decreased; these changes might be involved in the development of small resistance artery remodeling in humans.

Comparison between invasive and noninvasive techniques of evaluation of microvascular structural alterations.

BACKGROUND: The evaluation of the morphological characteristics of small resistance arteries in humans is challenging. The gold standard method is generally considered to be the measurement by wire or pressure micromyography of the media-to-lumen ratio of subcutaneous small vessels obtained by local biopsies. However, noninvasive techniques for the evaluation of retinal arterioles were recently proposed; in particular, two approaches, scanning laser Doppler flowmetry (SLDF) and adaptive optics, seem to provide useful information; both of them provide an estimation of the wall-to-lumen ratio (WLR) of retinal arterioles. Moreover, a noninvasive measurement of basal and total capillary density may be obtained by videomicroscopy/capillaroscopy. No direct comparison of these three noninvasive techniques in the same population was previously performed; in particular, adaptive optics was never validated against micromyography. METHODS: In the current study, we enrolled 41 controls and patients: 12 normotensive lean controls, 12 essential hypertensive lean patients, nine normotensive obese patients and eight hypertensive obese patients undergoing elective surgery. All patients underwent a biopsy of subcutaneous fat during surgery. Subcutaneous small resistance artery structure was assessed by wire micromyography and the media-to-lumen ratio was calculated. WLR of retinal arterioles was obtained by SLDF and adaptive optics. Functional (basal) and structural (total) microvascular density was evaluated by capillaroscopy before and after venous congestion. RESULTS AND CONCLUSION: Our data suggest that adaptive optics has a substantial advantage over SLDF in terms of evaluation of microvascular morphology, as WLR measured with adaptive optics is more closely correlated with the M/L of subcutaneous small arteries (r = 0.84, P < 0.001 vs. r = 0.52, P < 0.05, slopes of the relations: P < 0.01 adaptive optics vs. SLDF). In addition, the reproducibility of the evaluation of the WLR with adaptive optics is far better, as compared with SLDF, as intraobserver and interobserver variation coefficients are clearly smaller. This may be important in terms of clinical evaluation of microvascular morphology in a clinical setting, as micromyography has substantial limitations in its clinical application due to the local invasiveness of the procedure.

Use of Antihypertensive Drugs in Neoplastic Patients.

The introduction of Vascular Endothelial Growth Factor (VEGF) signaling pathway inhibitor treatment has highlighted the role of the baseline activity of the VEFG system for blood pressure regulation. VEGF signaling pathway is associated with hypertension and proteinuria. Activation of the endothelin system, endothelial dysfunction and capillary rarefaction are among the underlying mechanisms possibly explaining the rise in blood pressure and, to some extent, also the renal injury. The hypertension induced by VEGF signaling pathway inhibition is, usually, responsive to treatment. Recommendations about the management of cardiovascular toxicity in patients receiving VEGF signaling pathway inhibitors include a formal cardiovascular risk assessment before initiation of VEGF signaling pathway inhibitor treatment, active monitoring of blood pressure and cardiac toxicity throughout treatment, with more frequent monitoring during the first cycles of therapy, given that marked and unpredictable blood pressure rises can occur early after treatment with a VEGF signaling pathway inhibitor, and aggressive management of blood pressure elevations and early symptoms and signs of cardiac toxicity to prevent clinically limiting complications. In patients with preexisting hypertension, the blood pressure target for initiating VEGF signaling pathway inhibitor treatment should be <140/90 mmHg. Blockers of the renin-angiotensin system and calcium channel antagonists are among the drugs to be preferably used in these clinical conditions.

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.

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.

Effect of long-term treatment with melatonin on vascular markers of oxidative stress/inflammation and on the anticontractile activity of perivascular fat in aging mice.

Some reports have suggested that inflammation in perivascular adipose tissue (PVAT) may be implicated in vascular dysfunction by causing the disappearance of an anticontractile effect. The aim of this study was to investigate the effects of chronic melatonin treatment on the functional responses of the small mesenteric arteries and on the expression of markers of inflammation/oxidative stress in the aortas of senescence-accelerated prone mice (SAMP8), a model of age-related vascular dysfunction. We investigated seven SAMP8 and seven control senescence-accelerated resistant mice (SAMR1) treated for 10 months with melatonin, as well as equal numbers of age-matched untreated SAMP8 and SAMR1. The mesenteric small resistance arteries were dissected and mounted on a wire myograph, and the concentration-response to norepinephrine was evaluated in vessels with intact PVAT and after the removal of the PVAT. The expression of markers of oxidative stress, inflammation and aging in the aortas was evaluated by immunostaining. In addition, the adiponectin content and the expression of adiponectin receptor 1 were evaluated in the visceral adipose tissue. In untreated SAMP8 mice, we observed an overexpression of oxidative stress and inflammatory markers in the vasculature compared with the controls. No anticontractile effect of the PVAT was observed in untreated SAMP8 mice. Long-term treatment of SAMP8 mice with melatonin increased the expression of some markers of vasoprotection, decreased oxidative stress and inflammation and restored the anticontractile effect of the PVAT. Decreased expression of adiponectin and adiponectin receptor 1 was also observed in visceral fat of untreated SAMP8, whereas a significant increase was observed after melatonin treatment.

Trigger-oriented HIV testing at Internal Medicine hospital Departments in Northern Italy: an observational study (Fo.C.S. Study).

BACKGROUND: Early detection of undiagnosed HIV infected patients is of paramount importance. The attitude of Italian hospital-based Internal Medicine physicians to prescribe HIV testing following the detection of HIV-associated signs, symptoms and behaviours (triggers) has been reported to be poor. The aim of the study is to quantify the extent of the missed opportunities for early HIV diagnosis in Internal Medicine Departments (IMD). METHODS: Patients admitted to IMD of a General University Hospital in Italy in March-June 2013 were interviewed using a structured questionnaire investigating the presence of triggers for HIV testing, including patient's characteristics, symptoms and conditions associated with HIV infection. HIV tests performed during hospitalisation were recorded. RESULTS: HIV testing was performed in 73 (6.6%) out of 1113 hospitalisations (1072 patients), providing positive results in three cases (4.1%). All of them presented ≥1 triggers. Conversely, 853 triggers were identified in 528 hospitalisations with at least one trigger (47.4%). The proportion of hospitalisations where an HIV testing was prescribed was 3.1%, 9.5% and 16.0% in the presence of zero, one-to-two or more triggers, respectively. Age <70 years, female gender, length of hospital stay, haematological disease, HBV infection, multiple sexual partners and lymphadenopathy were predictors of HIV testing by logistic regression analysis. CONCLUSIONS: Although chances of an HIV test being performed in patients hospitalised in IMD increases along with the number of triggers, the number of tests being performed in people presenting with triggers is unacceptably low and requires educational interventions in order to obtain individual and public health advantages.

Cerebral small-resistance artery structure and cerebral blood flow in normotensive subjects and hypertensive patients.

INTRODUCTION: The aim of this study was to prospectively investigate whether the structure of cerebral small-resistance arteries is related to cerebral perfusion parameters as measured with dynamic susceptibility-weighted contrast magnetic resonance imaging (DSC-MRI) in a selected cohort of hypertensive and normotensive patients. METHODS: Ten hypertensive and 10 normotensive patients were included in the study. All patients underwent neurosurgical intervention for an intracranial tumor and were investigated with DSC-MRI at 1.5 T. Cerebral small-resistance arteries were dissected from a small portion of morphologically normal cerebral tissue and mounted on an isometric myograph for the measurement of the media-to-lumen (M/L) ratio. A quantitative assessment of cerebral blood flow (CBF) and volume (CBV) was performed with a region-of-interest approach. Correlation coefficients were calculated for normally distributed variables. The institutional review board approved the study, and informed consent was obtained from all patients. RESULTS: Compared with normotensive subjects, hypertensive patients had significantly lower regional CBF (mL/100 g/min) in the cortical grey matter (55.63 ± 1.90 vs 58.37 ± 2.19, p < 0.05), basal ganglia (53.34 ± 4.39 vs 58.22. ± 4.33, p < 0.05), thalami (50.65 ± 3.23 vs 57.56 ± 4.45, p < 0.01), subcortical white matter (19.32 ± 2.54 vs 22.24 ± 1.9, p < 0.05), greater M/L ratio (0.099 ± 0.013 vs 0.085 ± 0.012, p < 0.05), and lower microvessel density (1.66 ± 0.67 vs 2.52 ± 1.28, p < 0.05). A statistically significant negative correlation was observed between M/L ratio of cerebral arteries and CBF in the cortical grey matter (r = -0.516, p < 0.05), basal ganglia (r = -0.521, p < 0.05), thalami (r = -0.527 p < 0.05), and subcortical white matter (r = -0.612, p < 0.01). CONCLUSION: Our results indicate that microvascular structure might play a role in controlling CBF, with possible clinical consequences.

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.

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.

Anticontractile activity of perivascular fat in obese mice and the effect of long-term treatment with melatonin.

AIMS: It has been demonstrated previously that inflammation in perivascular adipose tissue (PVAT) may be implicated in vascular dysfunction. The aim of this study was to investigate the functional responses of small mesenteric arteries in a hyperphagic animal model of obesity after chronic treatment with melatonin, an endogenous hormone with antioxidant and vasculoprotective properties. METHODS AND RESULTS: Ten obese mice (ob/ob) and 10 control lean mice (CLM) were treated with melatonin 100  mg/kg per day in the drinking water for 8 weeks. Mesenteric small resistance arteries were dissected and mounted on a wire myograph and a concentration-response to norepinephrine was evaluated in vessels with intact PVAT and after PVAT was removed and in the presence of iberiotoxin, a selective blocker of BKCA channels as well as under conditions of induced hypoxia in vitro. The presence of PVAT reduced the contractile response to norepinephrine in both ob/ob and CLM; however, the effect was significantly reduced in ob/ob. The anticontractile effect of PVAT completely disappeared with iberiotoxin preincubation. After melatonin treatment, inflammation was significantly ameliorated, and the contractile response in ob/ob and CLM was significantly reduced when PVAT was removed. Anticontractile effect of PVAT that is lost in obesity can be rescued using melatonin. A reduced expression of adiponectin and adiponectin receptor was observed in perivascular fat of ob/ob, whereas significant increase was observed in ob/ob treated with melatonin. CONCLUSION: Melatonin seems to exert a protective effect on arteries from both ob/ob and CLM, counteracting the adverse effect of hypoxia and iberiotoxin.

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.

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.

Pulsatile hemodynamics and microcirculation: evidence for a close relationship in hypertensive patients.

The possible relationships between indicators of small resistance artery structure and of arterial stiffness and central hemodynamics have not yet been evaluated. Aim of this study was to assess the relationship between indicators of large arteries stiffness, including carotido-femoral pulse wave velocity and of vascular alterations in small resistance arteries (media/lumen ratio, M/L) in patients with primary and secondary hypertension. In 73 patients (mean age, 53±14 years, 34 females, 25 with type 2 diabetes mellitus, 18 never treated) with essential (n=37) and secondary (n=36) hypertension, carotido-femoral pulse wave velocity was measured. In all patients, small resistance arteries were dissected from subcutaneous fat biopsies and mounted on an isometric myograph, for the measurement of the M/L. Pulse wave analysis was performed in 67 patients. M/L ratio was significantly related to brachial systolic blood pressure and pulse pressure (r=0.36 and 0.31, P<0.001, respectively) and to central systolic and pulse pressure (r=0.44 and 0.42, P<0.001, respectively). A positive correlation was observed between M/L ratio and carotido-femoral pulse wave velocity (r=0.45; P<0.001); this correlation remained statistically significant after adjustment for age and mean blood pressure. M/L ratio was also associated to aortic augmentation index (r=0.33; P=0.008), and this correlations remained statistically significant after adjustment for potential confounders. In hypertensive patients, the presence of structural alterations of small resistance arteries may be associated with the increase in large arteries stiffness and possibly contribute to an increase in central pressure by increasing the magnitude of wave reflections.

Relationship between media-to-lumen ratio of subcutaneous small arteries and wall-to-lumen ratio of retinal arterioles evaluated noninvasively by scanning laser Doppler flowmetry.

BACKGROUND: Structural alterations of subcutaneous small resistance arteries, as indicated by an increased media-to-lumen ratio, are frequently present in hypertensive and/or diabetic patients, and may represent the earliest alteration observed. Furthermore, media-to-lumen ratio of small arteries evaluated by micromyography has a strong prognostic significance; however, its extensive evaluation is limited by the invasivity of the assessment, since a biopsy of subcutaneous fat is needed. Noninvasive measurement of wall-to-lumen of retinal arterioles using scanning laser Doppler flowmetry (SLDF) has recently been introduced. However, this new technique has not yet been compared to micromyographic measurement, generally considered the gold standard approach. METHODS AND RESULTS: We investigated 40 individuals and patients, 24 of them were hypertensive patients and 16 normotensive individuals. All patients underwent a biopsy of subcutaneous fat during an elective surgical intervention. Subcutaneous small resistance arteries were dissected and mounted on a wire myograph, and media-to-lumen ratio was measured. In addition, an evaluation of wall-to-lumen ratio of retinal arterioles by SLDF was performed (Heidelberg Retina Flowmeter, Heidelberg Engineering). A close correlation was observed between media-to-lumen ratio of subcutaneous small arteries and wall-to-lumen ratio of retinal arterioles (r = 0.76, P < 0.001; P < 0.001, r(2) = 0.57). CONCLUSION: A noninvasive and easily repeatable procedure (intraobserver and interobserver variation coefficient <13%) such as an evaluation of the arterioles in the fundus oculi by SLDF may provide similar information regarding microvascular morphology compared with an invasive, accurate and prognostically relevant micromyographic measurement of media-to-lumen ratio of subcutaneous small arteries.

Structural alterations in small resistance arteries in obesity.

In cardiovascular and metabolic diseases, small resistance arteries may show the presence of structural alterations. In particular, in essential hypertension, an increased media-to-lumen ratio of subcutaneous small arteries with no change in the total amount of vascular wall tissue (eutrophic remodelling) has already been described several years ago. Similar alterations have been demonstrated also in patients with diabetes mellitus and obesity; in this case, however, a more evident contribution of vascular smooth muscle cell growth (hypertrophic remodelling) is present. This review addresses the effects of obesity on small resistance artery structure. Similar to diabetic patients, obese patients show an increased media-to-lumen ratio of subcutaneous small arteries, which appears associated with hypertrophic remodelling, as demonstrated by an increase in media cross-sectional area. Endothelial dysfunction evaluated as vasodilator response to acetylcholine has also been observed. Several studies have shown that increased media-to-lumen ratio of subcutaneous small resistance arteries possesses a prognostic significance in relation to cardiovascular outcome. Appropriate antihypertensive treatment may improve microvascular alterations both in essential hypertension and in type 2 diabetes mellitus. In obesity, a pronounced weight loss may improve microvascular structure. However, further studies are needed to elucidate the effects of other pharmacological and non-pharmacological interventions in obesity.