Role of spleen in integrated control of splanchnic vascular tone: physiology and pathophysiology

A Model for Estimating Biological Age From Physiological Biomarkers of Healthy Aging: Cross-sectional Study

BACKGROUND

Individual differences in the rate of aging and susceptibility to disease are not accounted for by chronological age alone. These individual differences are better explained by biological age, which may be estimated by biomarker prediction models. In the light of the aging demographics of the global population and the increase in lifestyle-related morbidities, it is interesting to invent a new biological age model to be used for health promotion.

OBJECTIVE

This study aims to develop a model that estimates biological age based on physiological biomarkers of healthy aging.

METHODS

Carefully selected physiological variables from a healthy study population of 100 women and men were used as biomarkers to establish an estimate of biological age. Principal component analysis was applied to the biomarkers and the first principal component was used to define the algorithm estimating biological age.

RESULTS

The first principal component accounted for 31% in women and 25% in men of the total variance in the biological age model combining mean arterial pressure, glycated hemoglobin, waist circumference, forced expiratory volume in 1 second, maximal oxygen consumption, adiponectin, high-density lipoprotein, total cholesterol, and soluble urokinase-type plasminogen activator receptor. The correlation between the corrected biological age and chronological age was r=0.86 (P<.001) and r=0.81 (P<.001) for women and men, respectively, and the agreement was high and unbiased. No difference was found between mean chronological age and mean biological age, and the slope of the regression line was near 1 for both sexes.

CONCLUSIONS

Estimating biological age from these 9 biomarkers of aging can be used to assess general health compared with the healthy aging trajectory. This may be useful to evaluate health interventions and as an aid to enhance awareness of individual health risks and behavior when deviating from this trajectory.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03680768; https://clinicaltrials.gov/ct2/show/NCT03680768.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

RR2-10.2196/19209.

Splenectomy ameliorates portal pressure and anemia in animal models of cirrhotic and non-cirrhotic portal hypertension

PURPOSE

Portal hypertension (PH)-associated splenomegaly is caused by portal venous congestion and splanchnic hyperemia. This can trigger hypersplenism, which favors the development of cytopenia. We investigated the time-dependent impact of splenectomy on portal pressure and blood cell counts in animal models of non-cirrhotic and cirrhotic PH.

MATERIALS AND METHODS

Ninety-six rats underwent either partial portal vein ligation (PPVL), bile duct ligation (BDL), or sham operation (SO), with subgroups undergoing additional splenectomy. Portal pressure, mean arterial pressure, heart rate, blood cell counts and hemoglobin concentrations were evaluated throughout 5 weeks following surgery.

RESULTS

Following PPVL or BDL surgery, the animals presented a progressive rise in portal pressure, paralleled by decreased mean arterial pressure and accelerated heart rate. Splenectomy curbed the development of PH in both models (PPVL: 16.25 vs. 17.93 ​mmHg, p ​= ​0.083; BDL: 13.55 vs. 15.23 ​mmHg, p ​= ​0.028), increased mean arterial pressure (PPVL: +7%; BDL: +9%), and reduced heart rate (PPVL: -10%; BDL: -13%). Accordingly, splenectomized rats had lower von Willebrand factor plasma levels (PPVL: -22%; BDL: -25%). Splenectomy resulted in higher hemoglobin levels in PPVL (14.15 vs. 13.08 ​g/dL, p ​< ​0.001) and BDL (13.20 vs. 12.39 ​g/dL, p ​= ​0.097) animals, and significantly increased mean corpuscular hemoglobin concentrations (PPVL: +9%; BDL: +15%). Thrombocytopenia only developed in the PPVL model and was alleviated in the splenectomized subgroup. Conversely, BDL rats presented with thrombocytosis, which was not affected by splenectomy.

CONCLUSIONS

Splenectomy improves both cirrhotic and non-cirrhotic PH, and ameliorates the hyperdynamic circulation. Hypersplenism related anemia and thrombocytopenia were only significantly improved in the non-cirrhotic PH model.

Relationship between spleen size and exercise tolerance in advanced heart failure patients with a left ventricular assist device

OBJECTIVE

Spleen volume increases in patients with advanced heart failure (HF) after left ventricular assist device (LVAD) implantation. However, the relationship between spleen volume and exercise tolerance (peak oxygen consumption [VO₂]) in these patients remains unknown. In this exploratory study, we enrolled 27 patients with HF using a LVAD (median age: 46 years). Patients underwent blood testing, echocardiography, right heart catheterization, computed tomography (CT), and cardiopulmonary exercise testing. Spleen size was measured using CT volumetry, and the correlations/causal relationships of factors affecting peak VO₂ were identified using structural equation modeling.

RESULTS

The median spleen volume was 190.0 mL, and peak VO₂ was 13.2 mL/kg/min. The factors affecting peak VO₂ were peak heart rate (HR; β = 0.402, P = .015), pulmonary capillary wedge pressure (PCWP; β =  - 0.698, P = .014), right ventricular stroke work index (β = 0.533, P = .001), blood hemoglobin concentration (β = 0.359, P = .007), and spleen volume (β = 0.215, P = .041). Spleen volume correlated with peak HR, PCWP, and hemoglobin concentration, reflecting sympathetic activity, cardiac preload, and oxygen-carrying capacity, respectively, and was thus related to peak VO₂. These results suggest an association between spleen volume and exercise tolerance in advanced HF.

Association between splenic volume and pulsatility index in patients with left ventricular assist devices

The spleen serves as a blood volume reservoir for systemic volume regulation in heart failure (HF) patients. Changes are seen in spleen size in advanced HF patients after left ventricular assist device (LVAD) implantation. The pulsatility index (PI) is an indicator of native heart contractility with hemodynamic changes in patients using LVAD. We hypothesized that the splenic volume was associated with the PI, reflecting the hemodynamics in advanced HF patients with LVADs. Herein, we investigated the relationship between splenic volume and PI in these patients. Forty-four patients with advanced HF underwent implantation of HeartMate II^® (Abbott, Chicago, IL, USA) as a bridge to heart transplantation at the Nagoya University Hospital between October 2013 and June 2019. The data of 27 patients (21 men, median age 46 years) were analyzed retrospectively. All patients underwent blood tests, echocardiography, right heart catheterization, and computed tomography (CT). Spleen size was measured via CT volumetry; the splenic volume (median: 190 mL) correlated with right arterial pressure (r = 0.431, p = 0.025) and pulmonary capillary wedge pressure (r = 0.384, p = 0.048). On multivariate linear regression analysis, the heart rate (β = -0.452, p = 0.003), pump power (β = -0.325, p = 0.023), and splenic volume (β = 0.299, p = 0.038) were independent determinants of PI. The splenic volume was associated with PI, reflecting the cardiac preload in advanced HF patients with LVADs. Thus, spleen measurement using CT may help estimate the systemic volume status and understand the hemodynamic conditions in LVAD patients.

Right Heart Failure and Cardiorenal Syndrome

Cardiorenal syndrome is a complex interplay of dysregulated heart and kidney interaction that leads to multiorgan system dysfunction, which is not an uncommon occurrence in the setting of right heart failure. The traditional concept of impaired perfusion and forward flow recently has been modified to include the recognition of systemic venous congestion as a contributor, with direct and indirect mechanisms, including elevated renal venous pressure, reduced renal perfusion pressure, increased renal interstitial pressure, tubular dysfunction, splanchnic congestion, and neurohormonal and inflammatory activation. Treatment options beyond diuretics and vasoactive drugs remain limited and lack supportive evidence.

Fetal Portal System Flowmetry and Intra-Amniotic Inflammation in Preterm Prelabor Rupture of Membranes

OBJECTIVES

To determine the pulsatility index (PI) in the fetal splenic vein, the main portal vein, the left portal vein, and the ductus venosus with respect to the presence or absence of intra-amniotic inflammation (IAI) in preterm prelabor rupture of membranes (PPROM).

METHOD

Women with singleton pregnancies and PPROM, ranging in gestational age from 22+0 to 36+6 weeks, were included. Amniotic fluid samples were obtained by transabdominal amniocentesis and the amniotic fluid level of interleukin-6 (IL-6) was assessed by a point-of-care test. Doppler examination of the selected veins was performed, and the PI was assessed. IAI was defined as amniotic fluid levels of IL-6 ≥745 pg/mL.

RESULTS

In total, 42 women were included. Fetuses with IAI compared with those without IAI exhibited a higher PI in the splenic vein (p = 0.005) and the main portal vein (p = 0.05). No differences were observed in the left portal vein PI (p = 0.36) and the ductus venosus PI (p = 0.98).

CONCLUSION

IAI was associated with increased fetal splenic vein PI and main portal vein PI in PPROM. The absence of changes in the left portal vein PI and ductus venosus PI supports the local cause of the finding.

Acute Kidney Injury Due to Inferior Vena Cava Stenosis After Liver Transplantation: A Case Report About the Importance of Hepatic Vein Doppler Ultrasound and Clinical Assessment

Rationale:

Acute kidney injury (AKI) is a frequent complication after liver transplantation. In some patients, prompt intervention targeted at a specific etiology is of paramount importance.

Presenting concerns of the patients:

A 25 years old man with advanced liver cirrhosis caused by sclerosing cholangitis and autoimmune hepatitis underwent orthotopic liver transplantation. One month after surgery, severe AKI developed in conjunction with recurrent ascites and lower extremity edema. Notable clinical findings included a persistently low urinary sodium excretion, a bland urinary sediment, and an abnormally monophasic hepatic vein waveform on Doppler ultrasound.

Diagnoses:

Inferior vena cava stenosis.

Interventions:

Angioplasty with stent installation.

Outcomes:

Rapid improvement of renal function after stent installation.

Lessons learned:

The following case illustrates the importance of integrating clinical cues, ultrasound features, and laboratory findings. The combination of AKI associated with lower extremity edema, abnormal monophasic hepatic vein flow on Doppler ultrasound, and a low urinary sodium excretion after liver transplantation should evoke the possibility of inferior vena cava stenosis as the etiologic factor.

Splenic Doppler Resistive Index Variation Mirrors Cardiac Responsiveness and Systemic Hemodynamics upon Fluid Challenge Resuscitation in Postoperative Mechanically Ventilated Patients

OBJECTIVE

To test if splenic Doppler resistive index (SDRI) allows noninvasive monitoring of changes in stroke volume and regional splanchnic perfusion in response to fluid challenge. Design and Setting. Prospective observational study in cardiac intensive care unit.

PATIENTS

Fifty-three patients requiring mechanical ventilation and fluid challenge for hemodynamic optimization after cardiac surgery.

INTERVENTIONS

SDRI values were obtained before and after volume loading with 500 mL of normal saline over 20 min and compared with changes in systemic hemodynamics, determined invasively by pulmonary artery catheter, and arterial lactate concentration as expression of splanchnic perfusion. Changes in stroke volume >10% were considered representative of fluid responsiveness.

RESULTS

A <4% SDRI reduction excluded fluid responsiveness, with 100% sensitivity and 100% negative predictive value. A >9% SDRI reduction was a marker of fluid responsiveness with 100% specificity and 100% positive predictive value. A >4% SDRI reduction was always associated with an improvement of splanchnic perfusion mirrored by an increase in lactate clearance and a reduction in systemic vascular resistance, regardless of fluid responsiveness.

CONCLUSIONS

This study shows that SDRI variations after fluid administration is an effective noninvasive tool to monitor systemic hemodynamics and splanchnic perfusion upon volume administration, irrespective of fluid responsiveness in mechanically ventilated patients after cardiac surgery.

Connexin 43 in splenic lymphocytes is involved in the regulation of CD4+CD25+ T lymphocyte proliferation and cytokine production in hypertensive inflammation

Chronic inflammation promotes the development of hypertension and is associated with increased T cell infiltration and cytokine production in impaired organs. Gap junction protein connexin 43 (Cx43), is ubiquitously expressed in immune cells and plays an important role in T cell proliferation and activation, and cytokine production. However, the correlation between Cx43 in T cells and the hypertensive inflammatory response remains unknown. Thus, in this study, we wished to examine this correlation. First, our results revealed that hypertension caused significant thickening of the vascular wall, inflammatory cell infiltration into part of the renal interstitium and glomerular atrophy, and it increased the tubular damage scores in the kidneys of spontaneously hypertensive rats (SHRs). Moreover, the SHRs exhibited stenosis in the central artery wall of the spleen with increased serum levels of interleukin (IL)-2 and IL-6 compared with normotensive Wistar-Kyoto (WKY) rats. The spleens of the SHRs exhibited a significantly decreased percentage of CD4⁺CD25⁺ (Treg) T cells. However, the percentages of CD3⁺, CD4⁺ and CD8⁺ T cell and the levels of CD4⁺Cx43 and CD8⁺Cx43 did not differ significantly between the SHRs and WKY rats. In cultured lymphocytes from the SHRs and WKY rats, low percentages of Treg cells and reduced cytokine (IL-2 and IL-6) mRNA expression levels were observed in the lymphocytes obtained from the SHRs and WKY rats treated with the connexin blocker, Gap27, or concanavalin A (ConA) plus Gap27. The effects of ConA and Gap27 differed between the SHRs and WKY rats. On the whole, our findings demonstrate that the splenic Treg cell-mediated suppression in SHRs may be involved in hypertensive inflammatory responses. Cx43 in the gap junctional channel may regulate lymphocyte activation and inflammatory cytokine production.

Postsynaptic α1-Adrenergic Vasoconstriction Is Impaired in Young Patients With Vasovagal Syncope and Is Corrected by Nitric Oxide Synthase Inhibition

BACKGROUND

Syncope is a sudden transient loss of consciousness and postural tone with spontaneous recovery; the most common form is vasovagal syncope (VVS). During VVS, gravitational pooling excessively reduces central blood volume and cardiac output. In VVS, as in hemorrhage, impaired adrenergic vasoconstriction and venoconstriction result in hypotension. We hypothesized that impaired adrenergic responsiveness because of excess nitric oxide can be reversed by reducing nitric oxide.

METHODS AND RESULTS

We recorded cardiopulmonary dynamics in supine syncope patients and healthy volunteers (aged 15-27 years) challenged with a dose-response using the α1-agonist phenylephrine (PE), with and without the nitric oxide synthase inhibitor N(G)-monomethyl-L-arginine, monoacetate salt (L-NMMA). Systolic and diastolic pressures among control and VVS were the same, although they increased after L-NMMA and saline+PE (volume and pressor control for L-NMMA). Heart rate was significantly reduced by L-NMMA (P<0.05) for control and VVS compared with baseline, but there was no significant difference in heart rate between L-NMMA and saline+PE. Cardiac output and splanchnic blood flow were reduced by L-NMMA for control and VVS (P<0.05) compared with baseline, while total peripheral resistance increased (P<0.05). PE dose-response for splanchnic flow and resistance were blunted for VVS compared with control after saline+PE, but enhanced after L-NMMA (P<0.001). Postsynaptic α1-adrenergic vasoconstrictive impairment was greatest in the splanchnic vasculature, and splanchnic blood flow was unaffected by PE. Forearm and calf α1-adrenergic vasoconstriction were unimpaired in VVS and unaffected by L-NMMA.

CONCLUSIONS

Impaired postsynaptic α1-adrenergic vasoconstriction in young adults with VVS can be corrected by nitric oxide synthase inhibition, demonstrated with our use of L-NMMA.

Nitric oxide synthase inhibition restores orthostatic tolerance in young vasovagal syncope patients

OBJECTIVE

Syncope is sudden transient loss of consciousness and postural tone with spontaneous recovery; the most common form is vasovagal syncope (VVS). We previously demonstrated impaired post-synaptic adrenergic responsiveness in young VVS patients was reversed by blocking nitric oxide synthase (NOS). We hypothesised that nitric oxide may account for reduced orthostatic tolerance in young recurrent VVS patients.

METHODS

We recorded haemodynamics in supine VVS and healthy volunteers (aged 15-27 years), challenged with graded lower body negative pressure (LBNP) (-15, -30, -45 mm Hg each for 5 min, then -60 mm Hg for a maximum of 50 min) with and without NOS inhibitor N^G-monomethyl-L-arginine acetate (L-NMMA). Saline plus phenylephrine (Saline+PE) was used as volume and pressor control for L-NMMA.

RESULTS

Controls endured 25.9±4.0 min of LBNP during Saline+PE compared with 11.6±1.4 min for fainters (p<0.001). After L-NMMA, control subjects endured 24.8±3.2 min compared with 22.6±1.6 min for fainters. Mean arterial pressure decreased more in VVS patients during LBNP with Saline+PE (p<0.001) which was reversed by L-NMMA; cardiac output decreased similarly in controls and VVS patients and was unaffected by L-NMMA. Total peripheral resistance increased for controls but decreased for VVS during Saline+PE (p<0.001) but was similar following L-NMMA. Splanchnic vascular resistance increased during LBNP in controls, but decreased in VVS patients following Saline+PE which L-NMMA restored.

CONCLUSIONS

We conclude that arterial vasoconstriction is impaired in young VVS patients, which is corrected by NOS inhibition. The data suggest that both pre- and post-synaptic arterial vasoconstriction may be affected by nitric oxide.

Blunted cardiac response to hemorrhage in cirrhotic rats is mediated by local macrophage-released endocannabinoids

BACKGROUND & AIMS

Cirrhosis is associated with blunted cardiovascular response to stimuli such as hemorrhage, but the mechanism remains unclear. We aimed to clarify the role of endocannabinoids in blunted hemorrhage response in cirrhotic rats.

METHODS

Cirrhosis was induced by bile duct ligation (BDL). Hemodynamics were measured. Cannabinoid receptor-1 (CB1) antagonist, AM251, and macrophage inhibitor gadolinium chloride (GdCl3) were administered. Myocardial levels of anandamide (AEA) and 2-arachidonoyl glycerol (2-AG) were measured and resident monocytes and macrophages quantified by immunohistochemistry. Isolated cardiomyocyte contractility was measured before and after incubation with monocytes from BDL and sham controls.

RESULTS

Hemorrhage significantly decreased arterial pressure and left ventricular dP/dT. After hemorrhage, these changes quickly reversed in controls, but were severely prolonged in BDL rats. Chronic AM251 treatment restored this impaired response. AEA and 2-AG levels were increased in BDL hearts and further increased after hemorrhage. Sham hearts showed virtually no monocytes or macrophages before or after hemorrhage, whereas BDL hearts had significantly more white blood cells which further increased after hemorrhage. GdCl3 treatment significantly reduced cardiac endocannabinoid levels both at baseline and after hemorrhage. This treatment also restored cardiovascular response to hemorrhage in BDL rats but did not affect sham controls. Monocytes isolated from BDL rats more potently inhibited cardiomyocyte contractility than sham control monocytes.

CONCLUSIONS

The cirrhotic heart showed increased monocyte recruitment and endocannabinoid levels. CB1 blockade or GdCl3 treatment restored blunted cardiovascular response to hemorrhage. Endocannabinoids released by monocytes blunt cardiac response to hemorrhage. Preventing monocyte recruitment or blocking endocannabinoid signaling may improve cardiovascular homeostasis in cirrhosis.

Splenic Switch-off: A Tool to Assess Stress Adequacy in Adenosine Perfusion Cardiac MR Imaging

PURPOSE

To investigate the pharmacology and potential clinical utility of splenic switch-off to identify understress in adenosine perfusion cardiac magnetic resonance (MR) imaging.

MATERIALS AND METHODS

Splenic switch-off was assessed in perfusion cardiac MR examinations from 100 patients (mean age, 62 years [age range, 18-87 years]) by using three stress agents (adenosine, dobutamine, and regadenoson) in three different institutions, with appropriate ethical permissions. In addition, 100 negative adenosine images from the Clinical Evaluation of MR Imaging in Coronary Heart Disease (CE-MARC) trial (35 false and 65 true negative; mean age, 59 years [age range, 40-73 years]) were assessed to ascertain the clinical utility of the sign to detect likely pharmacologic understress. Differences in splenic perfusion were compared by using Wilcoxon signed rank or Wilcoxon rank sum tests, and true-negative and false-negative findings in CE-MARC groups were compared by using the Fisher exact test.

RESULTS

The spleen was visible in 99% (198 of 200) of examinations and interobserver agreement in the visual grading of splenic switch-off was excellent (κ = 0.92). Visually, splenic switch-off occurred in 90% of adenosine studies, but never in dobutamine or regadenoson studies. Semiquantitative assessments supported these observations: peak signal intensity was 78% less with adenosine than at rest (P < .001), but unchanged with regadenoson (4% reduction; P = .08). Calculated peak splenic divided by myocardial signal intensity (peak splenic/myocardial signal intensity) differed between stress agents (adenosine median, 0.34; dobutamine median, 1.34; regadenoson median, 1.13; P < .001). Failed splenic switch-off was significantly more common in CE-MARC patients with false-negative findings than with true-negative findings (34% vs 9%, P < .005).

CONCLUSION

Failed splenic switch-off with adenosine is a new, simple observation that identifies understressed patients who are at risk for false-negative findings on perfusion MR images. These data suggest that almost 10% of all patients may be understressed, and that repeat examination of individuals with failed splenic switch-off may significantly improve test sensitivity.

Changes in liver and spleen volumes after living liver donation: a report from the Adult-to-Adult Living Donor Liver Transplantation Cohort Study (A2ALL)

Previous reports have drawn attention to persistently decreased platelet counts among liver donors. We hypothesized an etiologic association between altered platelet counts and postdonation splenomegaly and sought to explore this relationship. This study analyzed de-identified computed tomography/magnetic resonance scans of 388 donors from 9 Adult-to-Adult Living Donor Liver Transplantation Cohort Study centers read at a central computational image analysis laboratory. Resulting liver and spleen volumes were correlated with time-matched clinical laboratory values. Predonation liver volumes varied 2-fold in healthy subjects, even when they were normalized by the body surface area (BSA; range = 522-1887 cc/m(2) , n = 346). At month 3 (M3), postdonation liver volumes were, on average, 79% of predonation volumes [interquartile range (IQR) = 73%-86%, n = 165] and approached 88% at year 1 (Y1; IQR = 80%-93%, n = 75). The mean spleen volume before donation was 245 cc (n = 346). Spleen volumes greater than 100% of the predonation volume occurred in 92% of donors at M3 (n = 165) and in 88% at Y1 after donation (n = 75). We sought to develop a standard spleen volume (SSV) model to predict normal spleen volumes in donors before donation and found that decreased platelet counts, a younger age, a higher predonation liver volume, higher hemoglobin levels, and a higher BSA predicted a larger spleen volume (n = 344, R(2)  = 0.52). When this was applied to postdonation values, some large volumes were underpredicted by the SSV model. Models developed on the basis of the reduced sample of postdonation volumes yielded smaller underpredictions. These findings confirm previous observations of thrombocytopenia being associated with splenomegaly after donation. The results of the SSV model suggest that the biology of this phenomenon is complex. This merits further long-term mechanistic studies of liver donors with an investigation of the role of other factors such as thrombopoietin and exposure to viral infections to better understand the evolution of the spleen volume after liver donation.

Impact of splenic circulation: non-invasive microbubble-based assessment of portal hemodynamics

OBJECTIVE

The objective was to examine the effect of splenic circulation using a microbubble agent to assess the severity of portal hypertension.

METHODS

This prospective study consisted of 91 subjects (63.0 ± 12.6 years, 30-86; 60 males, 31 females), 62 cirrhosis and 29 controls, who underwent both Doppler ultrasound and contrast-enhanced ultrasound with a perflubutane microbubble agent. Two microbubble-based parameters for splenic circulation, the minimum circulation time (MCT, s) and the peak enhancement time (PET, s), were assessed with respect to the hepatic venous pressure gradient (HVPG) and other clinical findings.

RESULTS

The MCT and PET showed significant differences between cirrhosis (5.7 ± 1.8; 14.6 ± 3.0) and controls (4.0 ± 1.9, p < 0.0001; 8.9 ± 2.3, p < 0.0001), respectively. However, only PET offered positive correlations with wedged hepatic venous pressure (r = 0.4648, p = 0.0001) and HVPG (r = 0.4573, p = 0.0001). The area under the receiver operating characteristics curve to identify HVPG ≥ 10 mmHg, and 12 mmHg was 0.76 and 0.76, respectively.

CONCLUSIONS

The microbubble-based non-invasive assessment of the splenic circulation is effective to identify the severity of portal hypertension presumably by reflecting congestion of splenic venous flow due to increased portal venous pressure.

Reflex control of inflammation by the splanchnic anti-inflammatory pathway is sustained and independent of anesthesia

Following an immune challenge, there is two-way communication between the nervous and immune systems. It is proposed that a neural reflex--the inflammatory reflex--regulates the plasma levels of the key proinflammatory cytokine TNF-α, and that its efferent pathway is in the splanchnic sympathetic nerves. The evidence for this reflex is based on experiments on anesthetized animals, but anesthesia itself suppresses inflammation, confounding interpretation. Here, we show that previous section of the splanchnic nerves strongly enhances the levels of plasma TNF-α in conscious rats 90 min after they received intravenous LPS (60 μg/kg). The same reflex mechanism, therefore, applies in conscious as in anesthetized animals. In anesthetized rats, we then determined the longer-term effects of splanchnic nerve section on responses to LPS (60 μg/kg iv). We confirmed that prior splanchnic nerve section enhanced the early (90 min) peak in plasma TNF-α and found that it reduced the 90-min peak of the anti-inflammatory cytokine IL-10; both subsequently fell to low levels in all animals. Splanchnic nerve section also enhanced the delayed rise in two key proinflammatory cytokines IL-6 and interferon γ. That enhancement was undiminished after 6 h, when other measured cytokines had subsided. Finally, LPS treatment caused hypotensive shock in rats with cut splanchnic nerves but not in sham-operated animals. These findings demonstrate that reflex activation of the splanchnic anti-inflammatory pathway has a powerful and sustained restraining influence on inflammatory processes.

Doppler assessment of splanchnic arterial flow in patients with liver cirrhosis: correlation with ammonia plasma levels and MELD score

PURPOSE

To assess the clinical significance of blood flow velocity and resistance index (RI) in the visceral arteries of patients with liver cirrhosis with respect to plasma ammonia (NH3) level and liver function.

METHODS

We included 80 patients with liver cirrhosis (58 men) and 20 healthy controls (11 men). Duplex Doppler ultrasonography was used to assess flow velocity and RI in the hepatic (HA), right (RRA), and left renal (LRA), and splenic (SA) (LA) artery. Plasma NH3 was measured by biochemistry. Liver function was assessed by MELD score (model of end-stage liver disease).

RESULTS

HA, LRA, and SA systolic flow velocities were greater, whereas RRA diastolic velocity was lower in patients with liver cirrhosis than in controls RI was higher in LRA, RRA, SA, and HA in patients with liver cirrhosis than in controls. NH3 levels were significantly elevated in all patients with liver cirrhosis (p < 0.05) and significantly correlated with RI of RRA, LRA, and SA.

CONCLUSION

We found greater renal, hepatic, and LA RI in patients with liver cirrhosis than in healthy controls. The correlation we found between elevated renal artery RI (≥0.70) and MELD score emphasizes the risk of renal dysfunction during progression of liver cirrhosis.

Physiological characterization of a mouse model of cachexia in colorectal liver metastases

Loss of skeletal muscle mass and function (cachexia) is severe in patients with colorectal liver metastases because of the large increase in resting energy expenditure but remains understudied because of a lack of suitable preclinical models. Our aim was to characterize a novel preclinical model of cachexia in colorectal liver metastases. We tested the hypothesis that mice with colorectal liver metastases would exhibit cachexia, as evidenced by a reduction in liver-free body mass, muscle mass, and physiological impairment. Twelve-week-old male CBA mice received an intrasplenic injection of Ringer solution (sham) or murine colorectal cancer cells (MoCR) to induce colorectal liver metastases. At end-point (20-29 days), the livers of MoCR mice were infiltrated completely with metastases, and MoCR mice had reduced liver-free body mass, muscle mass, and epididymal fat mass compared with sham controls (P < 0.03). MoCR mice exhibited impaired rotarod performance and grip strength (P < 0.03). Histochemical analyses of tibialis anterior muscles from MoCR mice revealed muscle fiber atrophy and reduced oxidative enzyme activity (P < 0.001). Adipose tissue remodeling was evident in MoCR mice, with reduced adipocyte diameter and greater infiltration of nonadipocyte tissue (P < 0.05). These findings reveal the MoCR mouse model exhibits significant cachexia and is a suitable preclinical model of cachexia in colorectal liver metastases. This model should be used for identifying effective treatments for cachexia to improve quality of life and reduce mortality in patients with colorectal liver metastases.

Splenic Doppler resistive index for early detection of occult hemorrhagic shock after polytrauma in adult patients

The objective of this study was to evaluate whether direct assessment of splenic circulation by splenic Doppler resistive index (Doppler RI) is a clinically useful noninvasive method for an early detection of occult hemorrhagic shock after polytrauma in adult patients. Splenic Doppler RI was measured in 49 hemodynamically stable adult patients admitted to the emergency department because of polytrauma. Renal Doppler RI was also determined in 20 patients. Spleen size, Injury Severity Score, systolic blood pressure, heart rate, blood lactate, standard base excess, pH, hemoglobin, and inferior vena cava diameter values were recorded at admission and at 24 h. Patients were grouped according to whether signs of hemorrhagic shock did (n = 22) or did not (n = 27) occur within the first 24 h from admission. Patients who developed hemorrhagic shock had significantly higher splenic and renal Doppler RI, higher Injury Severity Score, and lower standard base excess at admission. By multivariate logistic regression, splenic Doppler RI resulted to be a predictor of hemorrhagic shock development within the first 24 h from admission. Splenic Doppler RI may represent a clinically useful noninvasive method for early detection of occult hemorrhagic shock and persistent occult hypoperfusion after polytrauma in adult patients.

Mathematical modeling the neuroregulation of blood pressure using a cognitive top-down approach

Background:

The body′s physiological stability is maintained by the influence of the autonomic nervous system upon the dynamic interaction of multiple systems. These physiological systems, their nature and structure, and the factors which influence their function have been poorly defined. A greater understanding of such physiological systems leads to an understanding of the synchronised function of organs in each neural network i.e. there is a fundamental relationship involving sensory input and/or sense perception, neural function and neural networks, and cellular and molecular biology. Such an approach compares with the bottom-up systems biology approach in which there may be an almost infinite degree of biochemical complexity to be taken into account.

Aims:

The purpose of this article is to discuss a novel cognitive, top-down, mathematical model of the physiological systems, in particular its application to the neuroregulation of blood pressure.

Results:

This article highlights the influence of sensori-visual input upon the function of the autonomic nervous system and the coherent function of the various organ networks i.e. the relationship which exists between visual perception and pathology.

Conclusions:

The application of Grakov′s model may lead to a greater understanding of the fundamental role played by light e.g. regulating acidity, levels of Magnesium, activation of enzymes, and the various factors which contribute to the regulation of blood pressure. It indicates that the body′s regulation of blood pressure does not reside in any one neural or visceral component but instead is a measure of the brain′s best efforts to maintain its physiological stability.

Portal hypertensive cardiovascular pathology: the rescue of ancestral survival mechanisms?

The portal system derives from the vitelline system, which is an extra-embryonic venous system. It could be suggested that this extraembryonic origin determines some of the characteristics attributed to portal hypertension, both compensated, i.e. prehepatic, and decompensated, i.e. fibrotic or cirrhotic. The experimental models most frequently used for studying both types of portal hypertension are portal vein ligation and common bile duct ligation in rats, respectively. We propose that in partial portal vein ligated rats, a low-grade inflammatory response, formed by the successive expression of three overlapping phenotypes - ischemia-reperfusion, vitellogenic-like and remodeling or gastrulation-like - is produced. The names of these inflammatory phenotypes developed in compensated portal hypertension are based on some metabolic similarities that can be established with the abovementioned phases of embryonic development. In bile-duct ligated rats, decompensation related to hepatic insufficiency would induce a high-grade inflammatory response. In this experimental model, the splanchnic interstitium, the mesenteric lymph and the peritoneal mesothelium seem to create an inflammatory axis that produces ascites. The functional comparison between the ascitic and the amniotic fluids would imply that, in the decompensated portal hypertensive syndrome, the abdominal mesothelium acquires properties of the amniotic membranes or amnion. In conclusion, the hypothetical comparison between the inflammatory portal hypertensive evolutive types and the evolutive phases of embryonic development could allow for translational research.

Phosphodiesterase 4 inhibition attenuates plasma volume loss and transvascular exchange in volume-expanded mice

We tested the hypothesis that inhibition of phosphodiesterase 4 (PDE4) with rolipram to increase vascular endothelial cAMP and stabilize the endothelial barrier would attenuate the action of endogenous atrial natriuretic peptide (ANP) to increase vascular permeability to the plasma protein albumin after an acute plasma volume expansion. After rolipram pretreatment (8 mg (kg body wt)(-1), intraperitoneal, 30 min) more than 95% of the peak increase in plasma volume after volume expansion (4.5% bovine serum albumin, 114 μl (g body wt)(-1) h(-1), 15 min) remained in the vascular space 75 min after the end of infusion, whereas only 67% of the fluid was retained in volume-expanded animals with no rolipram pretreatment. Rolipram significantly decreased 30 min fluorescently labelled albumin clearance (μl (g dry wt)(-1)) relative to untreated volume-expanded controls in skin (e.g. back, 10.4 ± 1.6 vs. 19.5 ± 3.6, P = 0.04), muscle (e.g. hamstring, 15.0 ± 1.9 vs. 20.8 ± 1.4, P = 0.04) and in colon, caecum, and rectum (average reduction close to 50%). The mass of muscle and skin tissue accounted for 70% of volume-expansion-dependent albumin shifts from plasma to interstitium. The results are consistent with observations that the PDE4 inhibitor rolipram attenuates ANP-induced increases in vascular permeability after infusion of exogenous ANP and observations of elevated central venous pressure after a similar volume expansion in mice with selective deletion of the endothelial ANP receptor. These observations may form the basis for new strategies to retain intravenous fluid containing macromolecules.

Is spleen circulation impaired in systemic sclerosis and what is the role of liver fibrosis?

AIM: To investigate the spleen vascular involvement and the presence of liver fibrosis in a population of subjects with established systemic sclerosis (SSc).

METHODS: In a cross-sectional fashion, 17 patients with SSc were compared with 18 patients suffering from hepatitis C virus (HCV)-related liver cirrhosis, grade A and B Child-Pugh classification. Eighteen non elderly subjects, apparently healthy, were used as the control group. Splenic artery resistivity index (SARI) at doppler ultraSound, transient elastography of liver and nailfold capillaroscopy were the main outcomes.

RESULTS: Transient elastography values of SSc patients were similar to those of controls; 5.2 ± 1.1 vs 4.5 ± 1, (P = 0.07). Median Alanine amino transferase (ALT) concentrations of cirrhotic patients were greater than those of controls and SSc patients, i.e. 66.5 (36-89) U/L vs 29 (22-34) U/L and 31 (22-41) U/L, respectively, (P = 0.005). SARI determinations in cirrhotic patients, although significantly higher than those found in controls and SSc patients, showed some degree of overlap with SSc patients, i.e. 0.59 vs 0.52 and 0.57, respectively, (P = 0.04). Mean systolic blood pressure was significantly higher in SSc patients than in cirrhotics and controls, i.e. 142 mmHg vs 128.2 mmHg and 127 mmHg, respectively, (P = 0.005). Mean diastolic blood pressure behaved in a similar fashion, i.e. 84 mmHg vs 72.2 mmHg and 76.9 mmHg (P = 0.005). Nailfold Capillaroscopy grades and diastolic blood pressure values correlated well with SARI results.

CONCLUSION: An enhanced resistivity of the splenic artery was found in patients suffering from SSc; they did not have evidence of splenomegaly as well as no liver fibrosis or any other form of liver damage.

The interstitial lymphatic peritoneal mesothelium axis in portal hypertensive ascites: when in danger, go back to the sea

Portal hypertension induces a splanchnic and systemic low-grade inflammatory response that could induce the expression of three phenotypes, named ischemia-reperfusion, leukocytic, and angiogenic phenotypes.During the splanchnic expression of these phenotypes, interstitial edema, increased lymph flow, and lymphangiogenesis are produced in the gastrointestinal tract. Associated liver disease increases intestinal bacterial translocation, splanchnic lymph flow, and induces ascites and hepatorenal syndrome. Extrahepatic cholestasis in the rat allows to study the worsening of the portal hypertensive syndrome when associated with chronic liver disease. The splanchnic interstitium, the mesenteric lymphatics, and the peritoneal mesothelium seem to create an inflammatory pathway that could have a key pathophysiological relevance in the production of the portal hypertension syndrome complications. The hypothetical comparison between the ascitic and the amniotic fluids allows for translational investigation. From a phylogenetic point of view, the ancestral mechanisms for amniotic fluid production were essential for animal survival out of the aquatic environment. However, their hypothetical appearance in the cirrhotic patient is considered pathological since ultimately they lead to ascites development. But, the adult human being would take advantage of the potential beneficial effects of this “amniotic-like fluid” to manage the interstitial fluids without adverse effects when chronic liver disease aggravates.

Sympathetic nervous system overactivity and its role in the development of cardiovascular disease

This review examines how the sympathetic nervous system plays a major role in the regulation of cardiovascular function over multiple time scales. This is achieved through differential regulation of sympathetic outflow to a variety of organs. This differential control is a product of the topographical organization of the central nervous system and a myriad of afferent inputs. Together this organization produces sympathetic responses tailored to match stimuli. The long-term control of sympathetic nerve activity (SNA) is an area of considerable interest and involves a variety of mediators acting in a quite distinct fashion. These mediators include arterial baroreflexes, angiotensin II, blood volume and osmolarity, and a host of humoral factors. A key feature of many cardiovascular diseases is increased SNA. However, rather than there being a generalized increase in SNA, it is organ specific, in particular to the heart and kidneys. These increases in regional SNA are associated with increased mortality. Understanding the regulation of organ-specific SNA is likely to offer new targets for drug therapy. There is a need for the research community to develop better animal models and technologies that reflect the disease progression seen in humans. A particular focus is required on models in which SNA is chronically elevated.

Does spleen volume play a role in patients with HCV-related chronic hepatitis?

As the lymphotropism of hepatitis C virus (HCV) has already been ascertained, and in the light of the fact that the immune defense system is an organized network composed of functionally interrelated tissues, this study was carried out to verify the possible involvement of spleen in HCV-related chronic hepatitis. In this cross-sectional study we measured spleen longitudinal diameter by ultrasound, beta2-microglobulin serum levels and splenic artery resistivity index (SARI) by Doppler in 51 patients treated with standard combined (Peg-Interferon plus Ribavirin) antiviral therapy. Thirty-three patients (17 females) completed the regimen and were compared to 31 controls (16 females). The mean basal values of spleen longitudinal diameter were higher in patients with chronic hepatitis than in controls, i.e., 116 mm (9.4) versus 102.7 mm (9.3), P = 0.0001. In the same patients a significant trend towards increased spleen longitudinal diameter was found after antiviral therapy, independently of the stage of HCV-related chronic hepatitis. The median values of the beta2-microglobulin concentrations were not significantly higher in the patients with HCV-related chronic hepatitis compared to controls, i.e., 1.3 (0.5-2.6) versus 1 (0.6-1.4), P = 0.16, although during the course of therapy they were significantly increased. SARI values of HCV-related chronic hepatitis patients were different from those of controls, but were unvaried compared to values at the end of treatment. Neither spleen measurements nor serum beta2-microglobulin levels were able to predict therapeutic response to antiviral therapy. A stimulation/expansion of lymphoid tissue was found in patients with HCV-related chronic hepatitis. Such evidence raises the question whether physicians should continue to prescribe antiviral therapy in non-responders and supports the use of a new scheme (SLD plus beta2-MG) to diagnose this ongoing, apparently reversible, but nevertheless dangerous immunologic process.

Atrial natriuretic peptide modulation of albumin clearance and contrast agent permeability in mouse skeletal muscle and skin: role in regulation of plasma volume

Atrial natriuretic peptide (ANP) via its guanylyl cyclase-A (GC-A) receptor participates in regulation of arterial blood pressure and vascular volume. Previous studies demonstrated that concerted renal diuretic/natriuretic and endothelial permeability effects of ANP cooperate in intravascular volume regulation. We show that the microvascular endothelial contribution to the hypovolaemic action of ANP can be measured by the magnitude of the ANP-induced increase in blood-to-tissue albumin transport, measured as plasma albumin clearance corrected for intravascular volume change, relative to the corresponding increase in ANP-induced renal water excretion. We used a two-tracer method with isotopically labelled albumin to measure clearances in skin and skeletal muscle of: (i) C57BL6 mice; (ii) mice with endothelium-restricted deletion of GC-A (floxed GC-A x tie2-Cre: endothelial cell (EC) GC-A knockout (KO)); and (iii) control littermates (floxed GC-A mice with normal GC-A expression levels). Comparison of albumin clearances in hypervolaemic EC GC-A KO mice with normovolaemic littermates demonstrated that skeletal muscle albumin clearance with ANP treatment accounts for at most 30% of whole body clearance required for ANP to regulate plasma volume. Skin microcirculation responded to ANP similarly. Measurements of permeability to a high molecular mass contrast agent (35 kD Gadomer) by dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) enabled repeated measures in individual animals and confirmed small increases in muscle and skin microvascular permeability after ANP. These quantitative methods will enable further evaluation of the contribution of ANP-dependent microvascular beds (such as gastro-intestinal tract) to plasma volume regulation.

What are the implications of the spontaneous spleno-renal shunts in liver cirrhosis?

Background

Although significant advances are expected to be made in the assessment of the portal hypertension-related complications, the prognostic role of spleno-renal shunts has not been fully explored so far. Clarifying this aspect could help tackle the life-treating events occurring in patients suffering from liver cirrhosis. The aim of the study was to analyze the relationships between the spleno-renal shunts presence at doppler ultrasound and the liver cirrhosis complications.

Methods

Design: eighty one patients out of 129 formed the study population (35 females). Chronic liver damage in these patients was caused by HCV (66), HBV (2), alcohol abuse (2) or unknown etiology, likely non-alcoholic steatohepatitis (11). Setting: two Liver Units of university/primary hospitals in Southern Italy. Main outcome measures: grading of esofageal varices; detection of ascites: assessment of hepatic encephalopathy; evaluation of liver cirrhosis severity; tracking hepatocellular carcinoma; doppler features of spleno-renal shunts and splenic flow velocity; spleen longitudinal diameter at sonography.

Results

The prevalence of spleno-renal shunts was 18.5%, without no difference concerning the etiology (HCV versus non-HCV, p = 0.870); the prevalence of hepatocellular carcinoma in patients with spleno-renal shunts was superior to that of patients without them (Pearson Chi-square, p = 0.006, power of sample size 74%), also after adjustment for liver decompensation (p = 0.024). The median score of hepatic encephalopathy in patients with and without spleno-renal shunts was similar, i.e., 0 (range, 0-2) versus 0 (0 - 3), p = 0.67. The median splenic vein flow velocity in patients with spleno-renal shunts was significantly inferior to that of patients without them, i.e., 13 cm/sec (95% confidence intervals, 6-18) versus 21 cm/sec (17-24), p < 0.0001. By far the largest percentage of large esophageal varices was in patients without spleno-renal shunts (p = 0.005). In contrast, the frequency of ascites and hepatic encephalopathy severity was overlapping in the two groups. BMI values but not Child-Pugh's classification predicted spleno-renal shunts (Ors = 1.84, 95% confidence intervals = 1.28-2.64, p = 0.001 and 1.145, 95% confidence intervals = 0.77-1.51, p = 0.66).

Conclusion

Taking into consideration the relatively small sample size, patients with spleno-renal shunts are burdened by an increased incidence of hepatocellular carcinoma. BMI predicted the spleno-renal shunts presence.

Neural control of renal function

The renal nerves are the communication link between the central nervous system and the kidney. In response to multiple peripheral and central inputs, efferent renal sympathetic nerve activity is altered so as to convey information to the major structural and functional components of the kidney, the vessels, glomeruli, and tubules, each of which is innervated. At the level of each of these individual components, information transfer occurs via interaction of the neurotransmitter released at the sympathetic nerve terminal-neuroeffector junction with specific postjunctional receptors coupled to defined intracellular signaling and effector systems. In response to normal physiological stimuli, changes in efferent renal sympathetic nerve activity contribute importantly to homeostatic regulation of renal blood flow, glomerular filtration rate, renal tubular epithelial cell solute and water transport, and hormonal release. Afferent input from sensory receptors located in the kidney participates in this reflex control system via renorenal reflexes that enable total renal function to be self-regulated and balanced between the two kidneys. In pathophysiological conditions, abnormal regulation of efferent renal sympathetic nerve activity contributes significantly to the associated abnormalities of renal function which, in turn, are of importance in the pathogenesis of the disease.