Transplanted liver: consequences of denervation for liver functions

Development of posttransplant diabetes mellitus in US recipients of liver transplant is influenced by OPTN region

Posttransplant diabetes mellitus (PTDM) is associated with significant morbidity and mortality in liver transplant recipients (LTRs). We used the Organ Procurement and Transplantation Network (OPTN) database to compare the incidence of developing PTDM across the United States and develop a risk prediction model for new-onset PTDM using OPTN region as well as donor-related, recipient-related, and transplant-related factors. All US adult, primary, deceased donor, LTRs between January 1, 2007, and December 31, 2016, with no prior history of diabetes noted , were identified. Kaplan-Meier estimators were used to calculate the cumulative incidence of PTDM, stratified by OPTN region. Multivariable Cox proportional hazards models were fitted to estimate hazards of PTDM in each OPTN region and build a risk prediction model, through backward selection. Cumulative incidence of PTDM at 1 year, 3 years, and 5 years after transplant was 12.0%, 16.1%, and 18.9%, respectively. Region 3, followed by regions 8, 2, and 9, had the highest adjusted hazards of developing PTDM. Inclusion of OPTN region in a risk prediction model for PTDM in LTRs (including recipient age, sex, race, education, insurance coverage, body mass index, primary liver disease, cold ischemia time, and donor history of diabetes) modestly improved performance (C-statistic = 0.60). In patients without pre-existing, confirmed diabetes mellitus, the incidence of PTDM in LTRs varied across OPTN regions, with the highest hazards in region 3, followed by regions 8, 2, and 9. The performance of a novel risk prediction model for PTDM in LTRs has improved performance with the inclusion of the OPTN region. Vigilance is recommended to centers in high-risk regions to identify PTDM and mitigate its development.

Avoidant Restrictive Food Intake Disorder in Pediatric Liver Transplant Patients

INTRODUCTION

Following liver transplantation (LT), adequate nutrition is essential, as malnutrition may contribute to slower growth in pediatric patients and put patients at risk of complications following transplant. Avoidant Restrictive Food Intake Disorder (ARFID) is an eating disorder characterized by restrictive eating patterns that compromise nutrition. Patients with ARFID may have significant difficulty meeting nutritional needs due to fear of gastrointestinal distress, making it especially difficult to manage in patients following LT.

METHODS

We performed a retrospective chart review of de-identified patients who received LT at our institution. Two patients with ARFID who had undergone LT were identified. Their diagnoses, clinical courses, and post LT outcomes are reported. A literature review of the presentation and diagnosis of ARFID in pediatric patients and nutritional management of pediatric LT patients was performed. No IRB review was required given the sample size of two patients, per UCSF IRB rules and regulations.

RESULTS

We present two unique cases of ARFID: one with onset prior to LT and one with onset following LT. Outpatient psychiatry treatment was essential for nutritional management for the patient who developed ARFID following LT. The other patient continues to see a dietitian given ongoing nausea that limits her oral intake but does not receive any psychiatric support.

CONCLUSIONS

ARFID and selective eating patterns are rare but notable occurrences after pediatric LT, but they may also be underreported given the novelty of ARFID and the prevalence of gastrointestinal symptoms following transplant. Our case adds to the limited literature on ARFID in children following major surgical procedures and highlights the importance of interdisciplinary care and the importance of nutritional management in pediatric patients prior to and post LT.

Spinal cord injury induces transient activation of hepatic stellate cells in rat liver

Spinal cord injury (SCI) causes abnormal liver function, the development of metabolic dysfunction-associated steatotic liver disease features and metabolic impairment in patients. Experimental models also demonstrate acute and chronic changes in the liver that may, in turn, affect SCI recovery. These changes have collectively been proposed to contribute to the development of a SCI-induced metabolic dysfunction-associated steatohepatitis (MASH). However, none of the existent studies have focused on hepatic stellate cells (HSCs), liver resident cells that are the primary drivers of collagen deposition and fibrosis following sustained liver damage. Here, we describe the transient activation of HSCs after a thoracic contusion in rats, considered a clinically relevant model of experimental SCI. We studied HSC during the time course of SCI, from 1 to 45 days post injury. We found a transient activation of HSCs after SCI, beginning with the acute downregulation of Glial Fibrillar Acidic Protein 1dpi. This is followed by a morphological and phenotypical transformation into alpha-smooth muscle actin (ACTA2/SMA) immunoreactive myofibroblast-like cells, peaking at 14 days post-injury and returning to control-like levels at later timepoints (45 days post-injury). These changes are not accompanied by fibrosis development but collagen deposition in peri-portal areas is observed at 45 days.

The role of the nervous system in liver diseases

The nervous system significantly participates in maintaining homeostasis, and modulating repair and regeneration processes in the liver. Moreover, the nervous system also plays an important role in the processes associated with the development and progression of liver disease, and can either potentiate or inhibit these processes. The aim of this review is to describe the mechanisms and pathways through which the nervous system influences the development and progression of liver diseases, such as alcohol-associated liver disease, nonalcoholic fatty liver disease, cholestatic liver disease, hepatitis, cirrhosis, and hepatocellular carcinoma. Possible therapeutic implications based on modulation of signals transduction between the nervous system and the liver are also discussed.

Distribution and developmental timing of zebrafish liver innervation

Hepatic innervation regulates multiple aspects of liver function, repair and regeneration, and liver denervation is associated with higher rates of metabolic disorders in humans. However, the mechanisms regulating the development of the hepatic nervous system, as well as the role of the hepatic nervous system in liver development and maturation, are still largely unknown. Zebrafish are a widely used model of liver development and regeneration, but hepatic innervation in zebrafish has not yet been described in detail. Here, we examine the extent and developmental timing of hepatic innervation in zebrafish. We demonstrate that innervation is restricted to large bile ducts and blood vessels in both juvenile and adult zebrafish livers, as we find no evidence for direct innervation of hepatocytes. Innervation contacting the periphery of the liver is visible as early as 72 h post-fertilization, while intrahepatic innervation is not established until 21 days post-fertilization. Therefore, zebrafish hepatic innervation resembles that of previously examined fish species, making them an excellent model to investigate both the role of the hepatic nervous system during liver maturation and the mechanisms governing the elaboration of the intrahepatic nerve network between fish and mammals.

The Sympathetic-Immune Milieu in Metabolic Health and Diseases: Insights from Pancreas, Liver, Intestine, and Adipose Tissues

Sympathetic innervation plays a crucial role in maintaining energy balance and contributes to metabolic pathophysiology. Recent evidence has begun to uncover the innervation landscape of sympathetic projections and sheds light on their important functions in metabolic activities. Additionally, the immune system has long been studied for its essential roles in metabolic health and diseases. In this review, the aim is to provide an overview of the current research progress on the sympathetic regulation of key metabolic organs, including the pancreas, liver, intestine, and adipose tissues. In particular, efforts are made to highlight the critical roles of the peripheral nervous system and its potential interplay with immune components. Overall, it is hoped to underscore the importance of studying metabolic organs from a comprehensive and interconnected perspective, which will provide valuable insights into the complex mechanisms underlying metabolic regulation and may lead to novel therapeutic strategies for metabolic diseases.

Multi-organ denervation: a novel approach to combat cardiometabolic disease

Cardiometabolic disorders are associated with a substantial loss in quality of life and pose a large burden on healthcare systems worldwide. Overactivation of the sympathetic nervous system has been shown to be a key player in several aspects relating to cardiometabolic disturbances. While diet- and exercise-induced approaches to help reduce weight remains the main strategy to combat metabolic disorders, this is often difficult to achieve. Current pharmacological approaches result in variable responses in different patient cohorts and long-term efficacy may be limited by medication side effects and non-adherence in the long term. There is a clear clinical need for complementary therapies to curb the burden of cardiometabolic disease. One such approach may include interventional sympathetic neuromodulation of organs relevant to cardiometabolic control. Data from sham-controlled clinical trials demonstrate the feasibility, safety and efficacy of catheter-based renal denervation. In analogy, denervation of the common hepatic artery is now feasible in humans and may prove to be similarly useful in modulating sympathetic overdrive directed towards the liver, pancreas and duodenum. Such a targeted multi-organ neuromodulation strategy may beneficially influence multiple aspects of the cardiometabolic disease continuum including blood pressure, glucose and lipid control.

Hepatic Innervations and Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disorder. Increased sympathetic (noradrenergic) nerve tone has a complex role in the etiopathomechanism of NAFLD, affecting the development/progression of steatosis, inflammation, fibrosis, and liver hemodynamical alterations. Also, lipid sensing by vagal afferent fibers is an important player in the development of hepatic steatosis. Moreover, disorganization and progressive degeneration of liver sympathetic nerves were recently described in human and experimental NAFLD. These structural alterations likely come along with impaired liver sympathetic nerve functionality and lack of adequate hepatic noradrenergic signaling. Here, we first overview the anatomy and physiology of liver nerves. Then, we discuss the nerve impairments in NAFLD and their pathophysiological consequences in hepatic metabolism, inflammation, fibrosis, and hemodynamics. We conclude that further studies considering the spatial-temporal dynamics of structural and functional changes in the hepatic nervous system may lead to more targeted pharmacotherapeutic advances in NAFLD.

Intra-Abdominal Hypertension and Compartment Syndrome after Pediatric Liver Transplantation: Incidence, Risk Factors and Outcome

In pediatric liver transplantation (pLT), the risk for the manifestation and relevance of intra-abdominal hypertension (IAH) and abdominal compartment syndrome (ACS) is high. This observational study aimed to evaluate the incidence, relevance and risk factors for IAH and ACS by monitoring the intra-abdominal pressure (IAP), macro- and microcirculation (near-infrared spectroscopy (NIRS)), clinical and laboratory status and outcomes of 27 patients (16 female) after pLT (median age at pLT 35 months). Of the patients, 85% developed an elevated IAP, most of them mild. However, 17% achieved IAH° 3, 13% achieved IAH° 4 and 63% developed ACS. A multiple linear regression analysis identified aortal hepatic artery anastomosis and cold ischemia time (CIT) as risk factors for increased IAP and longer CIT and staged abdominal wall closure for ACS. ACS patients had significantly longer mechanical ventilation (p = 0.004) and LOS-PICU (p = 0.003). No significant correlation between NIRS or biliary complications and IAH or ACS could be shown. IAH and ACS after pLT were frequent. NIRS or grade of IAH alone should not be used for monitoring. A longer CIT is an important risk factor for higher IAP and ACS. Therefore, approaches such as the ex vivo machine perfusion of donor organs, reducing CIT effects on them, have great potential. Our study provides important basics for studying such approaches.

Bodily obsessions: intrusiveness of organs in somatic obsessive-compulsive disorder

In this paper, I will provide a phenomenological analysis of somatic obsessions at times present in obsessive-compulsive disorder. I will compare two different types of bodily obsessions, which have a different neurological-physiological underpinning: anguishing awareness of one's own heartbeat and of one's own breathing. In addition, I will contrast these two with how one experiences one's own liver. I will use the concepts "tactility obsessions" and "motility obsessions", which I have coined for the purpose of this comparison. In other words, these are obsessions concerning the felt sense of one's autonomous organs and obsessions concerning one's ability to voluntarily move. Ultimately, I claim that the core lived experience in somatic obsessive-compulsive disorder should not only be understood as having to do with intruding and "distorted thoughts" concerning bodily processes, but could also be understood as having to do with a felt sense of our organs interrupting and intruding our daily lives.

One of the Primary Functions of Tissue-Resident Pluripotent Pericytes Cells May Be to Regulate Normal Organ Growth and Maturation: Implications for Attempts to Repair Tissues Later in Life

Adult mesenchymal stem cells were reported more than 30 years ago. Since then, their potential to repair and regenerate damaged or diseased tissues has been studied intensively in both preclinical models and human trials. Most of the need for such tissue repair/regeneration is in older populations, so much of the effort has been performed with autologous cells in older patients. However, success has been difficult to achieve. In the literature, it has been noted that such progenitor cells from younger individuals often behave with more vigorous activity and are functionally enhanced compared to those from older individuals or animals. In addition, cells with the characteristics of mesenchymal stem cells or pluripotent mesenchymal regulatory cells exist in nearly all tissues and organs as pericytes since fetal life. Such evidence raises the possibility that one of the primary roles of these organ-specific cells is to regulate organ growth and maturation, and then subsequently play a role in the maintenance of organ integrity. This review will discuss the evidence to support this concept and the implications of such a concept regarding the use of these progenitor cells for the repair and regeneration of tissues damaged by injury or disease later in life. For the latter, it may be necessary to return the organ-specific progenitor cells to the functional state that contributed to their effectiveness during growth and maturation rather than attempting to use them after alterations imposed during the aging process have been established and their function compromised.

Long-term normothermic machine preservation of human livers: what is needed to succeed?

Although short-term machine perfusion (≤24 h) allows for resuscitation and viability assessment of high-risk donor livers, the donor organ shortage might be further remedied by long-term perfusion machines. Extended preservation of injured donor livers may allow reconditioning, repairing, and regeneration. This review summarizes the necessary requirements and challenges for long-term liver machine preservation, which requires integrating multiple core physiological functions to mimic the physiological environment inside the body. A pump simulates the heart in the perfusion system, including automatically controlled adjustment of flow and pressure settings. Oxygenation and ventilation are required to account for the absence of the lungs combined with continuous blood gas analysis. To avoid pressure necrosis and achieve heterogenic tissue perfusion during preservation, diaphragm movement should be simulated. An artificial kidney is required to remove waste products and control the perfusion solution's composition. The perfusate requires an oxygen carrier, but will also be challenged by coagulation and activation of the immune system. The role of the pancreas can be mimicked through closed-loop control of glucose concentrations by automatic injection of insulin or glucagon. Nutrients and bile salts, generally transported from the intestine to the liver, have to be supplemented when preserving livers long term. Especially for long-term perfusion, the container should allow maintenance of sterility. In summary, the main challenge to develop a long-term perfusion machine is to maintain the liver's homeostasis in a sterile, carefully controlled environment. Long-term machine preservation of human livers may allow organ regeneration and repair, thereby ultimately solving the shortage of donor livers.

Hepatic Nervous System in Development, Regeneration, and Disease

The liver is innervated by autonomic and sensory fibers of the sympathetic and parasympathetic nervous systems that regulate liver function, regeneration, and disease. Although the importance of the hepatic nervous system in maintaining and restoring liver homeostasis is increasingly appreciated, much remains unknown about the specific mechanisms by which hepatic nerves both influence and are influenced by liver diseases. While recent work has begun to illuminate the developmental mechanisms underlying recruitment of nerves to the liver, evolutionary differences contributing to species-specific patterns of hepatic innervation remain elusive. In this review, we summarize current knowledge on the development of the hepatic nervous system and its role in liver regeneration and disease. We also highlight areas in which further investigation would greatly enhance our understanding of the evolution and function of liver innervation.

Disorganization and degeneration of liver sympathetic innervations in nonalcoholic fatty liver disease revealed by 3D imaging

Hepatic nerves have a complex role in synchronizing liver metabolism. Here, we used three-dimensional (3D) immunoimaging to explore the integrity of the hepatic nervous system in experimental and human nonalcoholic fatty liver disease (NAFLD). We demonstrate parallel signs of mild degeneration and axonal sprouting of sympathetic innervations in early stages of experimental NAFLD and a collapse of sympathetic arborization in steatohepatitis. Human fatty livers display a similar pattern of sympathetic nerve degeneration, correlating with the severity of NAFLD pathology. We show that chronic sympathetic hyperexcitation is a key factor in the axonal degeneration, here genetically phenocopied in mice deficient of the Rac-1 activator Vav3. In experimental steatohepatitis, 3D imaging reveals a severe portal vein contraction, spatially correlated with the extension of the remaining nerves around the portal vein, enlightening a potential intrahepatic neuronal mechanism of portal hypertension. These fundamental alterations in liver innervation and vasculature uncover previously unidentified neuronal components in NAFLD pathomechanisms.

Safety of surgical denervation of the common hepatic artery in insulin-resistant dogs

The objective of this study was to assess the safety of surgical common hepatic artery denervation (CHADN). This procedure has previously been shown to improve glucose tolerance in dogs fed a high-fat high-fructose (HFHF) diet. We assessed the hypoglycemic response of dogs by infusing insulin at a constant rate (1.5 mU/kg/min) for 3 h and monitoring glucose and the counterregulatory hormones (glucagon, catecholamine, and cortisol). After an initial hypoglycemic study, the dogs were randomly assigned to a SHAM surgery (n = 4) or hepatic sympathetic denervation (CHADN, n = 5) and three follow-up studies were performed every month up to 3 months after the surgery. The level of norepinephrine (NE) in the liver and the pancreas was significantly reduced in the CHADN dogs, showing a decrease in sympathetic tone to the splanchnic organs. There was no evidence of any defect of the response to hypoglycemia after the CHADN surgery. Indeed, the extent of hypoglycemia was similar in the SHAM and CHADN groups (~45 mg/dl) for the same amount of circulating insulin (~50 µU/ml) regardless of time or surgery. Moreover the responses of the counterregulatory hormones were similar in extent and pattern during the 3 h of hypoglycemic challenge. Circulating lactate, glycerol, free fatty acids, and beta-hydroxybutyrate were also unaffected by CHADN during fasting conditions or during the hypoglycemia. There were no other notable surgery-induced changes over time in nutrients, minerals, and hormones clinically measured in the dogs nor in the blood pressure and heart rate of the animals. The data suggest that the ablation of the sympathetic nerve connected to the splanchnic bed is not required for a normal counterregulatory response to insulin-induced hypoglycemia and that CHADN could be a safe new therapeutic intervention to improve glycemic control in individuals with metabolic syndrome or type 2 diabetes.

Metabolic Consequences of Solid Organ Transplantation

Metabolic complications affect over 50% of solid organ transplant recipients. These include posttransplant diabetes, nonalcoholic fatty liver disease, dyslipidemia, and obesity. Preexisting metabolic disease is further exacerbated with immunosuppression and posttransplant weight gain. Patients transition from a state of cachexia induced by end-organ disease to a pro-anabolic state after transplant due to weight gain, sedentary lifestyle, and suboptimal dietary habits in the setting of immunosuppression. Specific immunosuppressants have different metabolic effects, although all the foundation/maintenance immunosuppressants (calcineurin inhibitors, mTOR inhibitors) increase the risk of metabolic disease. In this comprehensive review, we summarize the emerging knowledge of the molecular pathogenesis of these different metabolic complications, and the potential genetic contribution (recipient +/- donor) to these conditions. These metabolic complications impact both graft and patient survival, particularly increasing the risk of cardiovascular and cancer-associated mortality. The current evidence for prevention and therapeutic management of posttransplant metabolic conditions is provided while highlighting gaps for future avenues in translational research.

Role of the sympathetic nervous system in cardiometabolic control: implications for targeted multiorgan neuromodulation approaches

Sympathetic overdrive plays a key role in the perturbation of cardiometabolic homeostasis. Diet-induced and exercise-induced weight loss remains a key strategy to combat metabolic disorders, but is often difficult to achieve. Current pharmacological approaches result in variable responses in different patient cohorts and long-term efficacy may be limited by medication intolerance and nonadherence. A clinical need exists for complementary therapies to curb the burden of cardiometabolic diseases. One such approach may include interventional sympathetic neuromodulation of organs relevant to cardiometabolic control. The experience from catheter-based renal denervation studies clearly demonstrates the feasibility, safety and efficacy of such an approach. In analogy, denervation of the common hepatic artery is now feasible in humans and may prove to be similarly useful in modulating sympathetic overdrive directed towards the liver, pancreas and duodenum. Such a targeted multiorgan neuromodulation strategy may beneficially influence multiple aspects of the cardiometabolic disease continuum offering a holistic approach.

Diet and physical activity after liver transplant: A qualitative study of barriers and facilitators to following advice

BACKGROUND

Liver transplant recipients are given diet and physical activity advice to aid recovery and promote long-term health. The present study aimed to explore patients' experiences of receiving and implementing diet and physical activity advice after liver transplant and identify barriers and facilitators to following recommendations.

METHODS

A qualitative descriptive design included purposive sampling of 13 liver transplant recipients. Semi-structured audio-recorded interviews and inductive thematic analysis using a framework were undertaken concurrently to enable recruitment until saturation of themes occurred.

RESULTS

Overall experiences varied between participants and settings, as well as over time. Seven themes emerged, all representing both barriers and facilitators to implementing advice. Poor capability and loss of confidence were barriers that improved in hospital because healthcare professionals enabled participants to set and achieve goals but remained key barriers after discharge from hospital. The format and consistency of advice influenced participants' confidence in the healthcare team. Social support helped participants to return to and implement advice, although social networks could also have a negative influence. Advice and modelling of behaviour from other transplant recipients were facilitators. Symptoms, side effects, comorbidities and the environment presented barriers and facilitators. The desire to return to normal and coping strategies were drivers of behaviours, which were also influenced by participants' beliefs and values.

CONCLUSIONS

The variation in experiences indicates a need for individually tailored advice that is consistent across the multidisciplinary team. Interventions for behaviour change that merit further investigation include goal setting, improving coping strategies, peer support and modifying the hospital and home environment.

Combined renal and common hepatic artery denervation as a novel approach to reduce cardiometabolic risk: technical approach, feasibility and safety in a pre-clinical model

Background

Cardiovascular and metabolic regulation is governed by neurohumoral signalling in relevant organs such as kidney, liver, pancreas, duodenum, adipose tissue, and skeletal muscle. Combined targeting of relevant neural outflows may provide a unique therapeutic opportunity for cardiometabolic disease.

Objectives

We aimed to investigate the feasibility, safety, and performance of a novel device-based approach for multi-organ denervation in a swine model over 30 and 90 days of follow-up.

Methods

Five Yorkshire cross pigs underwent combined percutaneous denervation in the renal arteries and the common hepatic artery (CHA) with the iRF Denervation System. Control animals (n = 3) were also studied. Specific energy doses were administered in the renal arteries and CHA. Blood was collected at 30 and 90 days. All animals had a pre-terminal procedure angiography. Tissue samples were collected for norepinephrine (NEPI) bioanalysis. Histopathological evaluation of collateral structures and tissues near the treatment sites was performed to assess treatment safety.

Results

All animals entered and exited the study in good health. No stenosis or vessel abnormalities were present. No significant changes in serum chemistry occurred. NEPI concentrations were significantly reduced in the liver (− 88%, p = 0.005), kidneys (− 78%, p < 0.001), pancreas (− 78%, p = 0.018) and duodenum (− 95%, p = 0.028) following multi-organ denervation treatment compared to control animals. Histologic findings were consistent with favourable tissue responses at 90 days follow-up.

Conclusions

Significant and sustained denervation of the treated organs was achieved at 90 days without major safety events. Our findings demonstrate the feasibility of multi-organ denervation using a novel iRF Denervation System in a single procedure.

Neuronal innervation of the intestinal crypt

Mucosal damage is a key feature of inflammatory bowel diseases (IBD) and healing of the mucosa is an endpoint of IBD treatment that is often difficult to achieve. Autonomic neurons of the parasympathetic and sympathetic nervous system may influence intestinal epithelial cell growth and modulating epithelial innervation could for that reason serve as an interesting therapeutic option to improve mucosal healing. Understanding of the biological processes triggered by nonspecific and specific epithelial adrenergic and cholinergic receptor activation is of key importance. At present, with rising technological advances, bioelectronic neuromodulation as treatment modality has gained momentum. We discuss the current view on state-of-the-art innervation of the intestinal crypt and its impact on epithelial cell growth and differentiation. Furthermore, we outline bioelectronic technology and review its relevance to wound healing processes.

Metabolic syndrome following liver transplantation in nonalcoholic steatohepatitis

Metabolic syndrome is a major clinical disorder involving metabolic dysregulation characterized clinically with features of central obesity, insulin resistance (IR), type 2 diabetes, hypertension, and dyslipidemia. Metabolic syndrome is strongly associated with the rising prevalence nonalcoholic steatohepatitis, a leading indication for orthotopic liver transplantation in the Western world. The presence or recurrence of metabolic syndrome following liver transplantation can contribute to the development and recurrence of nonalcoholic fatty liver disease (NAFLD) in the liver allograft. In this review, we discuss the endogenous and exogenous drivers of post-transplant metabolic syndrome, role of chronic immunosuppression, and the prevalence and clinical significant of post-transplant metabolic syndrome on nonalcoholic steatohepatitis.

Clinical anatomy of the anterior and posterior hepatic plexuses, including relations with the pancreatic plexus: A cadaver study

The poor prognosis after surgery for pancreatic cancer or extrahepatic bile duct cancer has mainly been attributed to early lymph node metastasis, as well as a high frequency of perineural invasion along the peripancreatic neural plexuses or extrahepatic bile duct plexus. However, there has been no detailed morphological description of the anterior and posterior hepatic plexuses (AHP and PHP). In addition, the concepts of the pancreatic plexus and PHP are confused by surgeons. To assess the relations of the pancreatic plexus and hepatic plexuses from the morphological, developmental, and clinical perspectives, these plexuses were dissected in 24 cadavers. The PHP was found to be completely independent of the AHP. The PHP ran behind the portal vein, with most nerve fibers ascending along the bile duct to the gallbladder and the liver or descending to the distal common bile duct and duodenal papilla. Some branches of the PHP contributed to the pancreatic plexus, corresponding to pancreatic head plexus I as defined by the Japan Pancreas Society. The differences between the PHP and pancreatic head plexus I should be understood, even though liver function is not obviously affected after PHP excision for pancreatic head cancer. Further study is needed to determine whether there are functional differences between the AHP and PHP. Clin. Anat., 33:630-636, 2020. © 2019 Wiley Periodicals, Inc.

Shift in Sympathovagal Balance Toward Parasympathetic Predominance Is Associated With Attenuation of Portal Hyperperfusion in Cirrhotic Recipients Undergoing Living Donor Liver Transplant

BACKGROUND

The autonomic innervation to a liver graft remains lost up to 1 year after liver transplant. Therefore, we investigated the effects of recipients' autonomic nervous activity on the extent of portal hyperperfusion of a partial liver graft in the absence of the autonomic innervation.

METHODS

A total of 31 cirrhotic recipients undergoing right lobe living donor liver transplant were analyzed. Following a 10-minute absence of surgical stimulation after hepatic artery and bile duct reconstruction, the electrocardiogram and blood pressure waveforms were recorded for 5 minutes. Low-frequency (LF) and high-frequency (HF) powers and their ratio (LF/HF) were calculated using fast Fourier transform from the electrocardiogram waveform. A decrease in LF/HF represents a shift in sympathovagal balance toward parasympathetic predominance. Then, portal venous (PVF) and hepatic arterial (HAF) blood flows were measured in mL/min per 100 g of liver weight using spectral Doppler ultrasonography. A decrease in their ratio (PVF/HAF) represents attenuation of portal hyperperfusion.

RESULTS

The medians of the PVF and HAF were 349 and 27 mL/min/100 g liver weight with interquartile ranges of 272 to 617 mL/min/100 g liver weight and 22 to 41 mL/min/100 g liver weight, respectively, yielding a median of the PVF/HAF of 13.7 (interquartile range, 8.5-21.3). The median of LF/HF was 0.67 (interquartile range, 0.16-1.45). With a reduction in LF/HF, PVF/HAF decreased according to an S-curve regression model between them (PVF/HAF=e^{2.743+-0.031LF/HF},adjustedR²=0.129,P=0.027).

CONCLUSION

A shift in sympathovagal balance toward parasympathetic predominance is associated with attenuation of portal hyperperfusion in a partial liver graft.

Genetic loss of the muscarinic M3 receptor markedly alters bile formation and cholestatic liver injury in mice

AIM

Hepatic innervation represents a potentially underestimated regulator of liver function and regeneration. The muscarinic 3 receptor (M₃ -R) is the primary cholangiocyte receptor for the afferent parasympathetic innervation of bile ducts. We aimed to determine the specific role of the M₃ -R in bile formation and models for cholestatic liver disease in mice.

METHODS

We compared bile flow and composition in M₃ -R knock-out mice (M₃ -R^-/- ) and wild type littermates (WT). Furthermore, we compared liver inury of M₃ -R^-/- and WT mice after 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) feeding, a well-characterized preclinical model of cholestatic liver disease. To analyze the possible role of the M₃ -R as a therapeutic target, we treated 4-week-old Mdr2^-/- mice, a preclinical model for sclerosing cholangitis, with the M₃ -R agonist bethanechol for 4 weeks.

RESULTS

M₃ -R^-/- mice showed significantly reduced bile flow compared to WT mice, most likely due to decreased biliary HCO₃^- secretion. However, even aged M₃ -R^-/- mice did not spontaneously develop liver injury or cholestasis. Challenging M₃ -R^-/- and WT littermates with DDC feeding showed substantially aggravated liver injury in M₃ -R^-/- mice. After 4 weeks bethanechol treatment, Mdr2^-/- mice showed less liver injury compared to controls.

CONCLUSION

Our experimental findings suggest that M₃ -R-signalling significantly influences bile formation. Loss of the M₃ -R increases susceptibility to cholestatic injury in DDC-fed mice. Since treatment of Mdr2^-/- mice with a M₃ -R agonist decreases liver injury, M3-R signaling may represent a therapeutic target in specific cholangiopathies.

Cardiovascular risk after orthotopic liver transplantation, a review of the literature and preliminary results of a prospective study

Improved surgical techniques and greater efficacy of new anti-rejection drugs have significantly improved the survival of patients undergoing orthotopic liver transplantation (OLT). This has led to an increased incidence of metabolic disorders as well as cardiovascular and cerebrovascular diseases as causes of morbidity and mortality in OLT patients. In the last decade, several studies have examined which predisposing factors lead to increased cardiovascular risk (i.e., age, ethnicity, diabetes, NASH, atrial fibrillation, and some echocardiographic parameters) as well as which factors after OLT (i.e., weight gain, metabolic syndrome, immunosuppressive therapy, and renal failure) are linked to increased cardiovascular mortality. However, currently, there are no available data that evaluate the development of atherosclerotic damage after OLT. The awareness of high cardiovascular risk after OLT has not only lead to the definition of new but generally not accepted screening of high risk patients before transplantation, but also to the need for careful patient follow up and treatment to control metabolic and cardiovascular pathologies after transplant. Prospective studies are needed to better define the predisposing factors for recurrence and de novo occurrence of metabolic alterations responsible for cardiovascular damage after OLT. Moreover, such studies will help to identify the timing of disease progression and damage, which in turn may help to prevent morbidity and mortality for cardiovascular diseases. Our preliminary results show early occurrence of atherosclerotic damage, which is already present a few weeks following OLT, suggesting that specific, patient-tailored therapies should be started immediately post OLT.

Vagal innervation is required for the formation of tertiary lymphoid tissue in colitis

Tertiary lymphoid tissue (TLT) is lymphoid tissue that forms in adult life as a result of chronic inflammation in a tissue or organ. TLT has been shown to form in a variety of chronic inflammatory diseases, though it is not clear if and how TLT develops in the inflamed colon during inflammatory bowel disease. Here, we show that TLT develops as newly formed lymphoid tissue in the colon following dextran sulphate sodium induced colitis in C57BL/6 mice, where it can be distinguished from the preexisting colonic patches and solitary intestinal lymphoid tissue. TLT in the inflamed colon develops following the expression of lymphoid tissue-inducing chemokines and adhesion molecules, such as CXCL13 and VCAM-1, respectively, which are produced by stromal organizer cells. Surprisingly, this process of TLT formation was independent of the lymphotoxin signaling pathway, but rather under neuronal control, as we demonstrate that selective surgical ablation of vagus nerve innervation inhibits CXCL13 expression and abrogates TLT formation without affecting colitis. Sympathetic neuron denervation does not affect TLT formation. Hence, we reveal that inflammation in the colon induces the formation of TLT, which is controlled by innervation through the vagus nerve.

Metabolic syndrome and non-alcoholic fatty liver disease after liver or kidney transplantation

Transplantation is a definitive treatment option for patients with end-stage liver disease, and for some patients with acute liver failure, hepatocellular carcinoma or end-stage renal disease. Long-term post-transplantation complications have become an important medical issue, and cardiovascular diseases (CVD) are now the leading cause of mortality in liver or kidney transplant recipients. The increased prevalence of metabolic syndrome (MS) likely plays a role in the high incidence of post-transplantation CVD. MS and its hepatic manifestation, non-alcoholic fatty liver disease (NAFLD), are prevalent among the general population and in pre- and post-transplantation settings. MS components are associated with recurrent or de novo NAFLD in transplant recipients, potentially influencing post-transplantation survival. Moreover, recent data reveal an important association between NAFLD and risk of incident of chronic kidney disease (CKD). Therefore, NAFLD identification could represent an additional clinical feature for improving the stratification of liver and kidney transplant recipients with regards to risks of CVD, CKD and renal allograft dysfunction. All MS components are potentially modifiable; therefore, it is crucial that hepatologists, nephrologists and primary care physicians become more engaged in managing post-transplantation metabolic complications. The present review discusses the recent clinical evidence regarding the importance of MS and its components after liver and kidney transplantation, as well as the link between MS and NAFLD after liver and kidney transplantation.

Adipokines, inflammatory mediators, and insulin-resistance parameters may not be good markers of metabolic syndrome after liver transplant

OBJECTIVE

The role of adipokines in liver transplantation (LTx) recipients who have metabolic syndrome (MetS) has seldom been assessed. The aim of this study was to investigate the concentrations of adipokines, inflammatory mediators, and insulin-resistance markers in liver recipients with MetS and its components.

METHODS

Serum samples from 34 patients (55.9% male; 54.9 ± 13.9 y; 7.7 ± 2.9 y after LTx; 50% presented with MetS) were assessed for adiponectin, resistin, tumor necrosis factor (TNF)-α, monocyte chemoattractant protein (MCP)-1, interleukin (IL)-6, C-reactive protein (CRP), homeostatic model assessment-insulin resistance (HOMA-IR) and free fatty acid (FFA) levels. The dosages were uni- and multivariate analyzed to cover MetS (using the Harmonizing MetS criteria), its components, and dietary intake.

RESULTS

A higher concentration of adiponectin (P < 0.05) was observed among patients with MetS (5.2 ± 3.2 μg/mL) compared with those without MetS (3.2 ± 1.2 μg/mL), as well as those with MetS components versus those without them: abdominal obesity (4.6 ± 2.6 μg/mL versus 2.6 ± 0.6 μg/mL), high triacylglycerols (TGs; 5.6 ± 3.1 μg/mL versus 3 ± 0.9 μg/mL) and low high-density lipoprotein (HDL; 6.1 ± 2.7 μg/mL versus 3.3 ± 1.9 μg/mL). Increased TNF-α and HOMA-IR values were seen in patients with abdominal obesity. Patients with high TGs also had greater FFA values. Independent predictors for adiponectin were waist-to-hip ratio, low HDL and high TGs. High TGs and fasting blood glucose were independent predictors for HOMA-IR. Independent predictors could not be identified for CRP, TNF-α, MCP-1, IL-6, or FFA.

CONCLUSIONS

MetS and its components are related to an increased HOMA-IR concentration and FFA. Adiponectin, resistin, and inflammatory markers, such as TNF-α, IL-6, MCP-1, and CRP, were not associated with MetS in this sample of post-LTx patients.

A prospective observational study on tolerance and satisfaction to hepatic haemodynamic procedures

BACKGROUND

Understanding patients' attitudes to clinical experiences is essential for developing high-quality patient-centred healthcare, as a better knowledge of patients' tolerance and satisfaction might allow implementing measures that ameliorate comfort, care and use of resources.

AIMS

We aimed to describe patients' tolerance and satisfaction to invasive hepatic haemodynamic procedures, and to investigate which factors might influence patients' perspective in this field.

METHODS

Visual Analogue Scale (VAS) questionnaires regarding pain and duration (for tolerance), and comfort and general handling (for satisfaction) were prospectively administered to all consecutive patients (N = 327) submitted to hepatic haemodynamic procedures (N = 355) in a tertiary care setting during 2011. VAS scores ranged between 0 and 100 mm and items were defined as excellent if <10 mm; good if 10-20 mm and inadequate if >20 mm. Clinical and laboratory data were also collected.

RESULTS

Satisfaction was excellent in >95% of cases (mean 2 ± 5 mm, median 0 mm) and average tolerance was good (15 ± 18 mm; median 6 mm). A percentage of 59% of patients had excellent tolerance, 9% good and 32% had inadequate tolerance. Duration and complexity of the procedure and limited operator's experience were associated with inadequate tolerance on univariate analysis; duration of the procedure remained the only independent factor associated with inadequate tolerance on multivariate analysis. Procedures lasting <35 min had a >80% probability of being well tolerated.

CONCLUSIONS

Satisfaction and tolerance to hepatic haemodynamic procedures are excellent and good respectively. Tolerance was decreased in long procedures; hence reducing as much as possible the duration of the procedures might further improve tolerance.

Liver regeneration: immunohistochemical study of intrinsic hepatic innervation after partial hepatectomy in rats

Background

We examined the intrinsic hepatic innervation after partial hepatectomy (PH) in rats and the presence and pattern of neural sprouting in regenerating liver.

Methods

Male Wistar rats (age 9–13 weeks-w, weight 204-356 g), were submitted to two-thirds PH. Rats were sacrificed at postoperative days (d) 1, 3, 5, 7, at 2 and 4 w, and at 3 and 6 months (m) (6–7 animals/group, control group n = 4). Immunohistochemistry for the pan-neural marker protein gene product 9.5 (PGP9.5) and growth-associated protein 43 (GAP-43), a marker of regenerating nerve axons, was performed on tissue sections from the R1 lobe of the regenerating liver. Portal tracts (PTs) with immunoreactive fibers were counted in each section and computer-assisted morphometric analysis (Image Pro Plus) was used to measure nerve fiber density (number of immuno-positive nerve fibers/mm² (40x)).

Results

Immunoreactivity for PGP9.5 was positive in all groups. The number of PGP9.5 (+) nerve fibers decreased from 0.32 +/− 0.12 (control group) to 0.18 +/− 0.09 (1d post-PH group), and gradually increased reaching pre-PH levels at 6 m (0.3 +/− 0.01). In contrast, immunoreactivity for GAP-43 was observed at 5d post-PH, and GAP-43 (+) PTs percentage increased thereafter with a peak at 3 m post-PH. GAP-43 (+) nerve fiber density increased gradually from 5d (0.05 +/− 0.06) with a peak at 3 m post-PH (0.21 +/− 0.027). At 6 m post-PH, immunoreactivity for GAP-43 was not detectable.

Conclusions

Following PH in rats: 1) nerve fiber density in portal tracts decreases temporarily, and 2) neural sprouting in the regenerating liver lobes starts at 5d, reaches peak levels at 3 m and disappears at 6 m post-PH, indicating that the increase in hepatic mass after PH provides an adequate stimulus for the sprouting process.

Statin therapy is associated with the development of new-onset diabetes after transplantation in liver recipients with high fasting plasma glucose levels

New-onset diabetes after transplantation (NODAT) and dyslipidemia are important metabolic complications after liver transplantation (LT) that can adversely affect both allograft and patient survival. Statins are used as first-line therapies for dyslipidemia because of their effectiveness and safety profile. However, it has recently been reported that statin therapy is associated with new-onset diabetes in the nontransplant population. The aim of this study was to investigate the association between statin therapy and the development of NODAT in LT recipients. Three hundred sixty-four LT recipients who underwent transplantation between the ages of 20 and 75 years without a previous history of diabetes were enrolled in this study. We evaluated the incidence of NODAT with respect to statin use as well as other risk factors. The incidence of NODAT was significantly higher in the statin group (31.7%) versus the control group (17.6%, P = 0.03). The mean follow-up period was 37.8 ± 19.0 months for the statin group and 42.7 ± 16.0 months for the control group (P = 0.07). Statin use was significantly associated with NODAT development after adjustments for other risk factors [hazard ratio (HR) = 2.32, 95% confidence interval (CI) = 1.23-4.39, P = 0.01]. Impaired fasting glucose before transplantation was also a risk factor for NODAT development (HR = 2.21, 95% CI = 1.36-3.62, P = 0.001). There were no significant differences in age, body mass index, cumulative corticosteroid dose, or fasting plasma glucose (FPG) levels between the groups. Patients with high FPG levels were more likely to develop NODAT when they were placed on statins after LT (P = 0.002). In conclusion, statin treatment could contribute to the development of NODAT in LT recipients, especially if they have high baseline FPG levels.

Experimental liver autotransplantation with novel scheme of veno-venous bypass as a model of liver denervation and delymphatization

The impact of denervation and delymphatization (DD) on liver tissue remains a topic of major interest in liver transplantation, as the organ or its part continues to function well. Various chemical and/or surgical interventions have been developed to achieve in situ liver denervation and delymphatization, but it is evident that DD can be achieved only through "ectomia", ie, complete isolation of the organ from adjacent and connected structures. This Study describes a liver DD model based on a technique of autotransplantation (replantation), maximally preventing ischemia in the transplanted (replanted) graft and dyscirculatory complications in the recipient. Experiments were performed on eight male mongrel dogs. Venous reservoir and roller pumps were used in a forced nontraditional bypass scheme. Autotransplantation was performed by step-by-step dissection of the suprahepatic, infrahepatic, and portal structures, leading to DD, with subsequent recovery of the blood vessel and bile duct. DD was achieved successfully with stable hemodynamic parameters during all surgery periods. All animals survived. This model of liver autotransplantation lead to DD of the organ. It was characterized by hemodynamic stability of the liver as well as of the whole body at every stage of the surgery, proffering liver DD for experimental studies.

Hemodynamic response to propranolol in patients with recurrent hepatitis C virus-related cirrhosis after liver transplantation: a case-control study

Cirrhosis recurrence is frequent after orthotopic liver transplantation for hepatitis C virus (HCV). Because transplantation causes liver denervation, we hypothesized that the response to propranolol might differ in transplant patients versus nontransplant patients with cirrhosis and portal hypertension. Twenty-one patients with cirrhosis recurrence after orthotopic liver transplantation with portal hypertension were compared to 20 nontransplant patients with cirrhosis, HCV, and portal hypertension, and they were matched by sex, age, presence of varices, and Child-Pugh score. The patients underwent systemic and hepatic hemodynamic measurements at the baseline and 20 minutes after intravenous propranolol (0.15 mg/kg). At the baseline, the transplant patients with cirrhosis had a lower hepatic venous pressure gradient (HVPG) than the nontransplant patients with cirrhosis (14.8 ± 2.9 versus 17.3 ± 4.4 mm Hg, P = 0.03) but a higher mean arterial pressure (MAP; 100.3 ± 12.3 versus 91.8 ± 11.6 mm Hg, P = 0.04) and higher systemic vascular resistance (2253 ± 573 versus 1883 ± 525 dyn/second/cm(-5) , P = 0.03). There were no differences in the cardiac index (CI). Propranolol significantly decreased HVPG to similar extents in transplant patients and nontransplant patients with cirrhosis (-14.1% ± 8.0% versus -16.9% ± 9.5%, P > 0.99). MAP tended to increase in transplant patients with cirrhosis, whereas it slightly decreased in nontransplant patients (5.1% ± 14.2% versus -4.8% ± 6.4%, P = 0.007); however, the reduction in CI was less marked in transplant patients with cirrhosis (-18.6% ± 7.6% versus -26.9% ± 9.0%, P = 0.005). In conclusion, patients with HCV-related cirrhosis and portal hypertension after orthotopic liver transplantation have lower baseline HVPG values but similar HVPG responses to propranolol infusions in comparison with nontransplant patients with cirrhosis. In contrast to nontransplant patients, propranolol increases the systemic vascular resistance and arterial pressure in transplant patients with cirrhosis and attenuates the fall in CI.

Flow Competition between Hepatic Arterial and Portal Venous flow during Hypothermic Machine Perfusion Preservation of Porcine Livers

Hypothermic machine perfusion (HMP) is regarded as a better preservation method for donor livers than cold storage. During HMP, livers are perfused through the inlet blood vessels, namely the hepatic artery (HA) and the portal vein (PV). In previous HMP feasibility studies of porcine and human livers, we observed that the PV flow decreased while the HA flow increased. This flow competition restored either spontaneously or by lowering the HA pressure (PHA). Since this phenomenon had never been observed before and because it affects the HMP stability, it is essential to gain more insight into the determinants of flow competition. To this end, we investigated the influence of the HMP boundary conditions on liver flows during controlled experiments. This paper presents the flow effects induced by increasing PHA and by obstructing the outlet blood vessel, which is the vena cava inferior (VCI).

Flow competition was evoked by increasing PHA to 55–70 mmHg, as well as by obstructing the VCI. Remarkably, a severe obstruction resulted in a repetitive and alternating tradeoff between the HA and PV flows. These phenomena could be related to intra-sinusoidal pressure alterations. Consequently, a higher PHA is most likely transmitted to the sinusoidal level. This increased sinusoidal pressure reduces the pressure drop between the PV and the sinusoids, leading to a decreased PV perfusion. Flow competition has not been encountered or evoked under physiological conditions and should be taken into account for the design of liver HMP protocols. Nevertheless, more research is necessary to determine the optimal parameters for stable HMP.

Metabolic syndrome and liver transplantation: a review and guide to management

Metabolic syndrome is common among liver transplant recipients before and after transplantation. The components of metabolic syndrome are often exacerbated in the post-transplant period by transplant specific factors, such as immunosuppression, and are strong predictors of patient morbidity and mortality. Many aspects of the metabolic syndrome are modifiable. Early recognition, prevention and treatment of post-transplant hypertension, obesity, dyslipidemia and diabetes may impact long-term post-transplant survival. Further study into the prevention and management of these issues in the transplant patient are needed.

Afferent mechanisms of sodium retention in cirrhosis and hepatorenal syndrome

Cirrhosis induces extra-cellular fluid volume expansion, which when the disease is advanced can be severe and poorly responsive to therapy. Prevention and/or effective therapy for cirrhotic edema requires understanding the stimulus that initiates and maintains sodium retention. Despite much study, this stimulus remains unknown. Work over the last several years has shown that signals originating in the liver can influence a variety of systemic functions, including extra-cellular fluid volume control. We review work on the afferent mechanisms triggering sodium retention in cirrhosis and suggest that the data are most consistent with the existence of a sensor in the hepatic circulation that contributes to normal extra-cellular fluid volume control (that is, a 'volume' sensor) and that in cirrhosis, the sensor is pathologically activated by the hepatic circulatory abnormalities caused by the disease. Detailed analysis of the hepatic circulation in normal conditions and cirrhosis is needed.

Gastric afferents project to the aldosterone-sensitive HSD2 neurons of the NTS

The HSD2 (11-beta-hydroxysteroid dehydrogenase-type 2 enzyme) containing neurons of the nucleus tractus solitarius (NTS) become activated during low-sodium and high-aldosterone states such as hypovolemia. This response may be due to hormonal and/or neural signals. Hormonal signals may activate neurons in the area postrema that innervate the HSD2 neurons. The vagus nerve projects directly to the HSD2 neurons and this could be another route whereby these neurons receive information about systemic sodium/aldosterone status. The peripheral sites of origin that contribute to this vagal projection remain unknown, and in the present study, we injected the transganglionic tracer, cholera toxin beta-subunit-horseradish peroxidase (CTb-HRP), into wall of various gastrointestinal organs (stomach, small and large intestine) or liver of rats. Confocal microscopy of brainstem sections stained by a double immunohistochemical procedure was used to analyze whether the HSD2 neurons received axonal contacts from specific gastrointestinal structures. The major source of afferents arose from the stomach, mainly from its pyloric antrum, but a weaker input originated from the fundus region. A trace amount originated from the duodenum. The terminal part of the small intestine and large intestine did not to contribute to this projection. Similarly, no afferent inputs from the liver or portal vein were found. In conclusion, HSD2 neurons receive an input mainly from the stomach and these results are considered as potential sites affecting sodium intake.

Effects of nocturnal light on (clock) gene expression in peripheral organs: a role for the autonomic innervation of the liver

Background

The biological clock, located in the hypothalamic suprachiasmatic nucleus (SCN), controls the daily rhythms in physiology and behavior. Early studies demonstrated that light exposure not only affects the phase of the SCN but also the functional activity of peripheral organs. More recently it was shown that the same light stimulus induces immediate changes in clock gene expression in the pineal and adrenal, suggesting a role of peripheral clocks in the organ-specific output. In the present study, we further investigated the immediate effect of nocturnal light exposure on clock genes and metabolism-related genes in different organs of the rat. In addition, we investigated the role of the autonomic nervous system as a possible output pathway of the SCN to modify the activity of the liver after light exposure.

Methodology and Principal Findings

First, we demonstrated that light, applied at different circadian times, affects clock gene expression in a different manner, depending on the time of day and the organ. However, the changes in clock gene expression did not correlate in a consistent manner with those of the output genes (i.e., genes involved in the functional output of an organ). Then, by selectively removing the autonomic innervation to the liver, we demonstrated that light affects liver gene expression not only via the hormonal pathway but also via the autonomic input.

Conclusion

Nocturnal light immediately affects peripheral clock gene expression but without a clear correlation with organ-specific output genes, raising the question whether the peripheral clock plays a “decisive” role in the immediate (functional) response of an organ to nocturnal light exposure. Interestingly, the autonomic innervation of the liver is essential to transmit the light information from the SCN, indicating that the autonomic nervous system is an important gateway for the SCN to cause an immediate resetting of peripheral physiology after phase-shift inducing light exposures.

Functional anatomy of normal bile ducts

The biliary tree is a complex network of conduits that begins with the canals of Hering and progressively merges into a system of interlobular, septal, and major ducts which then coalesce to form the extrahepatic bile ducts, which finally deliver bile to the gallbladder and to the intestine. The biliary epithelium shows a morphological heterogeneity that is strictly associated with a variety of functions performed at the different levels of the biliary tree. In addition to funneling bile into the intestine, cholangiocytes (the epithelial cells lining the bile ducts) are actively involved in bile production by performing both absorbitive and secretory functions. More recently, other important biological properties restricted to cholangiocytes lining the smaller bile ducts have been outlined, with regard to their plasticity (i.e., the ability to undergo limited phenotypic changes), reactivity (i.e., the ability to participate in the inflammatory reaction to liver damage), and ability to behave as liver progenitor cells. Functional interactions with other branching systems, such as nerve and vascular structures, are crucial in the modulation of the different cholangiocyte functions.

The effect of denervation on liver regeneration in partially hepatectomized rats

BACKGROUND/AIM

In a partial liver transplantation, the dissected hepatic nerves are left unrepaired during active liver regeneration. In fact, the pathophysiological influence of such hepatic denervation on liver regeneration has not yet been fully clarified. The aim of the present study is to elucidate the effect of total hepatic denervation on liver regeneration.

METHODS

Experiment 1: To confirm the effect of hepatic denervation, the hepatic contents of norepinephrine were measured in both denervated (n = 5) and sham (n = 5) rats. The changes in the hepatic microcirculation were also measured in both denervated (n = 5) and sham (n = 5) rats. Experiment 2: The rats (n = 80) were randomly assigned to two groups: DN group (n = 40); hepatic denervation followed by a partial hepatectomy (PH). Control group (n = 40); sham hepatic denervation followed by PH. In both groups, the animals were killed at 12, 24, 36, 48, 72, 120, and 168 h after PH, respectively. The liver to body weight ratio and the proliferating cell nuclear antigen (PCNA) labeling index were measured at each time point.

RESULTS

Experiment 1: Nearly a total depletion of norepinephrine (<99%) was observed in the DN rats. In addition, the hepatic tissue blood flow significantly increased in the DN rats. Experiment 2: The liver to body weight ratio of the DN group was also significantly higher than that of the control group at 168 h (P < 0.05). The PCNA labeling index peaked between 24 and 36 h in the control group, while that in the DN group showed a delayed peak. At 72 and 120 h, the PCNA labeling index was significantly higher in the DN group than in the control group (P < 0.05).

CONCLUSION

Total hepatic denervation was thus found to enhance liver regeneration after a partial hepatectomy. This phenomenon is partially triggered by the increased hepatic blood flow to the remnant liver.

Cytoprotective effects of taurocholic acid feeding on the biliary tree after adrenergic denervation of the liver

BACKGROUND

Cholangiopathies impair the balance between proliferation and apoptosis of cholangiocytes leading to the disappearance of bile ducts and liver failure. Taurocholic acid (TC) is essential for cholangiocyte proliferative and functional response to cholestasis. Bile acids and neurotransmitters co-operatively regulate the biological response of the biliary epithelium to cholestasis. Adrenergic denervation of the liver during cholestasis results in the damage of bile ducts.

AIM

To verify whether TC feeding prevents the damage of the biliary tree induced by adrenergic denervation in the course of cholestasis.

METHODS

Rats subjected to bile duct ligation (BDL) and to adrenergic denervation were fed a TC-enriched diet, in the absence or presence of daily administration of the phosphatidyl-inositol-3-kinase (PI3K) inhibitor wortmannin for 1 week.

RESULTS

TC prevented the induction of cholangiocyte apoptosis induced by adrenergic denervation. TC also restored cholangiocyte proliferation and functional activity, reduced after adrenergic denervation. TC prevented AKT dephosphorylation induced by adrenergic denervation. The cytoprotective effects of TC were abolished by the simultaneous administration of wortmannin.

SUMMARY/CONCLUSIONS

TC administration prevents the damage of the biliary tree induced by the adrenergic denervation of the liver. These novel findings open novel perspectives in the understanding of the potential of bile acids especially in post-transplant liver disease.

Proliferating cholangiocytes: a neuroendocrine compartment in the diseased liver

In the last 15 years, the intrahepatic biliary tree has become the object of extensive studies, which highlighted the extraordinary biologic properties of cholangiocytes involved in bile formation, proliferation, injury repair, fibrosis, angiogenesis, and regulation of blood flow. Proliferation is a "typical" property of cholangiocytes and is key as a mechanism of repair responsible for maintaining the integrity of the biliary tree. Cholangiocyte proliferation occurs virtually in all pathologic conditions of liver injury where it is associated with inflammation, regeneration, and repair, thus conditioning the evolution of liver damage. Interestingly, proliferating cholangiocytes acquire the phenotype of neuroendocrine cells, and secrete different cytokines, growth factors, neuropeptides, and hormones, which represent potential mechanisms for cross talk with other liver cells. Many studies suggest the generation of a neuroendocrine compartment in the injured liver, mostly constituted by cells with cholangiocyte features, which functionally conditions the progression of liver disease. These insights on cholangiocyte pathophysiology will provide new potential strategies for the management of chronic liver diseases. The purpose of this review is to summarize the recent findings on the mechanisms regulating cholangiocyte proliferation and the significance of the neuroendocrine regulation of cholangiocyte biology.