Periportal Hepatocytes Research Articles

Expression pattern of thymosin beta 4 in the adult human liver

Thymosin beta-4 (Tβ4) is a member of beta-thymosins, a family of small peptides involved in polymerization of G-actin, and in many critical biological processes including apoptosis, cell migration, angiogenesis, and fibrosis. Previous studies in the newborn liver did not reveal any significant reactivity for Tβ4 during the intrauterine life. The aim of the present study was to investigate by immunohistochemistry Tβ4 expression in the adult normal liver. Thirty-five human liver samples, including 11 needle liver biopsies and 24 liver specimens obtained at autopsy, in which no pathological change was detected at the histological examination, were immunostained utilizing an anti-Tβ4 commercial antibody. Tβ4 was detected in the hepatocytes of all adult normal livers examined. A zonation of Tβ4 expression was evident in the vast majority of cases. Immunostaining was preferentially detected in zone 3, while a minor degree of reactivity was detected in periportal hepatocytes (zone 1). At higher power, Tβ4-reactive granules appeared mainly localized at the biliary pole of hepatocytes. In cases with a strong immunostaining, even perinuclear areas and the sinusoidal pole of hepatocytes appeared interested by immunoreactivity for Tβ4. The current work first evidences a strong diffuse expression of Tβ4 in the adult human liver, and adds hepatocytes to the list of human cells able to synthesize large amounts of Tβ4 in adulthood. Moreover, Tβ4 should be added to the liver proteins characterized by a zonate expression pattern, in a descending gradient from the terminal vein to the periportal areas of the liver acinus. Identifying the intimate role played by this peptide intracellularly and extracellularly, in physiology and in different liver diseases, is a major challenge for future research focusing on Tβ4.

The nuclear receptor FXR regulates hepatic transport and metabolism of glutamine and glutamate

Hepatic transport and metabolism of glutamate and glutamine are regulated by intervention of several proteins. Glutamine is taken up by periportal hepatocytes and is the major source of ammonia for urea synthesis and glutamate for N-acetylglutamate (NAG) synthesis, which is catalyzed by the N-acetylglutamate synthase (NAGS). Glutamate is taken up by perivenous hepatocytes and is the main source for the synthesis of glutamine, catalyzed by glutamine synthase (GS). Accumulation of glutamate and ammonia is a common feature of chronic liver failure, but mechanism that leads to failure of the urea cycle in this setting is unknown. The Farnesoid X Receptor (FXR) is a bile acid sensor in hepatocytes. Here, we have investigated its role in the regulation of the metabolism of both glutamine and glutamate. In vitro studies in primary cultures of hepatocytes from wild type and FXR −/− mice and HepG2 cells, and in vivo studies, in FXR −/− mice as well as in a rodent model of hepatic liver failure induced by carbon tetrachloride (CCl 4), demonstrate a role for FXR in regulating this metabolism. Further on, promoter analysis studies demonstrate that both human and mouse NAGS promoters contain a putative FXRE, an ER8 sequence. EMSA, ChIP and luciferase experiments carried out to investigate the functionality of this sequence demonstrate that FXR is essential to induce the expression of NAGS. In conclusion, FXR activation regulates glutamine and glutamate metabolism and FXR ligands might have utility in the treatment of hyperammonemia states.

Embryonic Ductal Plate Cells Give Rise to Cholangiocytes, Periportal Hepatocytes, and Adult Liver Progenitor Cells

BACKGROUND& AIMS: Embryonic biliary precursor cells form a periportal sheet called the ductal plate, which is progressively remodeled to generate intrahepatic bile ducts. A limited number of ductal plate cells participate in duct formation; those not involved in duct development are believed to involute by apoptosis. Moreover, cells that express the SRY-related HMG box transcription factor 9 (SOX9), which include the embryonic ductal plate cells, were proposed to continuously supply the liver with hepatic cells. We investigated the role of the ductal plate in hepatic morphogenesis. Apoptosis and proliferation were investigated by immunostaining of mouse and human fetal liver tissue. The postnatal progeny of SOX9-expressing ductal plate cells was analyzed after genetic labeling, at the ductal plate stage, by Cre-mediated recombination of a ROSA26RYFP reporter allele. Inducible Cre expression was induced by SOX9 regulatory regions, inserted in a bacterial artificial chromosome. Livers were studied from mice under normal conditions and during diet-induced regeneration. Ductal plate cells did not undergo apoptosis and showed limited proliferation. They generated cholangiocytes lining interlobular bile ducts, bile ductules, and canals of Hering, as well as periportal hepatocytes. Oval cells that appeared during regeneration also derived from the ductal plate. We did not find that liver homeostasis required a continuous supply of cells from SOX9-expressing progenitors. The ductal plate gives rise to cholangiocytes lining the intrahepatic bile ducts, including its most proximal segments. It also generates periportal hepatocytes and adult hepatic progenitor cells.

STEREOLOGICAL ESTIMATION OF ITO CELLS FROM RAT LIVER USING THE OPTICAL FRACTIONATOR - A PRELIMINARY REPORT

In the last two decades, much light has been shed on hepatic fibrosis, and the activation / proliferation of Ito cells (IC) emerged to play a central role. Therefore, it is essential to have solid quantitative data in nonpathological statuses; yet, this data is scarce and confined to "number per area" or semiquantitative information. Moreover, the supposed heterogeneous distribution of IC in the hepatic lobule was never analysed with design-based (unbiased) stereology. In the present study, the total number (N) of IC in rat liver was estimated for the first time, by combining immunocytochemistry with the optical fractionator. Quantification was extended to the hepatocytes, to disclose the IC index, an often-used ratio in hepatology. Systematic uniform random liver sections were obtained from male Wistar rats (n = 3), and immunostained against glial fibrillary acidic protein (GFAP), a known specific marker for hepatic IC. For the first time, these were marked against GFAP in thick (30 μm) paraffin sections. The estimated N of IC was 224E06; with a coefficient of error of 0.04 or 0.06, depending on the particular equation used (based on the so-called "quadratic approximation"). The IC index was 91 IC/1000 hepatocytes. Concerning the lobular heterogeneity, it was proved the liver harbours a larger total number of periportal IC and hepatocytes.

Liver‐specific‐aquaporin 11 knockout mice show rough endoplasmic reticulum dilation and vacuole formation in periportal hepatocytes in response to fasting and re‐feeding with regular chow or protein, and following oral amino acid load

Aquaporin 11 (AQP11) is a channel protein with unknown physiological function expressed in multiple organs. It has previously been shown that global AQP11 KO mice die early due to malfunction of the kidney caused by vacuolization of proximal tubule (Morishita et al., 2005). Here we report generation of liver-specific-AQP11 KO mice to study AQP11 function in the liver of mice with undisturbed kidney function. Microscopic analyses revealed that the liver in unstressed liver-specific-AQP11 KO mice shows no vacuolization. Fasting of the mice for 24 hours leads to slight dilatation of rough endoplasmic reticulum (RER) in the periportal hepatocytes. Re-feeding of the mice with regular mouse chow induces rapid generation of large vacuoles in the periportal hepatocytes. The same effect is obtained by oral administration of a protein or larger doses of different amino acids (Glu, Gln, Gly, Ala), while administration of glucose or triglyceride does not induce vacuolization. Only a sub-population of hepatocytes isolated from liver-specific-AQP11 KO mice develops vacuoles in vitro when cultured in medium supplemented with 20 mM glutamine. We propose that vacuolization of RER is a result of accumulation of a product(s) of amino acid metabolism inside the RER lumen and osmotic swelling of this compartment. The study was supported by Lundbeck Foundation.

Regulator of G Protein Signaling (RGS16) Inhibits Hepatic Fatty Acid Oxidation in a Carbohydrate Response Element-binding Protein (ChREBP)-dependent Manner

G protein-coupled receptor (GPCR) pathways control glucose and fatty acid metabolism and the onset of obesity and diabetes. Regulators of G protein signaling (RGS) are GTPase-activating proteins (GAPs) for G(i) and G(q) α-subunits that control the intensity and duration of GPCR signaling. Herein we determined the role of Rgs16 in GPCR regulation of liver metabolism. Rgs16 is expressed during the last few hours of the daily fast in periportal hepatocytes, the oxygen-rich zone of the liver where lipolysis and gluconeogenesis predominate. Rgs16 knock-out mice had elevated expression of fatty acid oxidation genes in liver, higher rates of fatty acid oxidation in liver extracts, and higher plasma β-ketone levels compared with wild type mice. By contrast, transgenic mice that overexpressed RGS16 protein specifically in liver exhibited reciprocal phenotypes as well as low blood glucose levels compared with wild type littermates and fatty liver after overnight fasting. The transcription factor carbohydrate response element-binding protein (ChREBP), which induces fatty acid synthesis genes in response to high carbohydrate feeding, was unexpectedly required during fasting for maximal Rgs16 transcription in liver and in cultured primary hepatocytes during gluconeogenesis. Thus, RGS16 provides a signaling mechanism for glucose production to inhibit GPCR-stimulated fatty acid oxidation in hepatocytes.

Variable responses of small and large human hepatocytes to hypoxia and hypoxia/reoxygenation (H–R)

Hypoxia and hypoxia–reoxygenation (H–R) regulate human hepatocyte cell death by mediating the accumulation of reactive oxygen species (ROS). Hepatocytes within the liver are organised into peri-portal (PP) and peri-venous (PV) subpopulations. PP and PV hepatocytes differ in size and function. We investigated whether PP and PV human hepatocytes exhibit differential susceptibility to hypoxic stress. Isolated hepatocytes were used in an in vitro model of hypoxia and H–R. ROS production and cell death were assessed using flow cytometry. PV, and not PP hepatocytes, accumulate intracellular ROS in a mitochondrial dependent manner during hypoxia and H–R. This increased ROS regulates hepatocyte apoptosis and necrosis via a mitochondrial pathway. These findings have implications on the understanding of liver injury and application of potential therapeutic strategies.

Isoflurane Activates Intestinal Sphingosine Kinase to Protect against Renal Ischemia–Reperfusion-induced Liver and Intestine Injury

Renal ischemia-reperfusion injury (IRI) is a major cause of acute kidney injury and often leads to multiorgan dysfunction and systemic inflammation. Volatile anesthetics have potent antiinflammatory effects. We aimed to determine whether the representative volatile anesthetic isoflurane protects against acute kidney injury-induced liver and intestinal injury and to determine the mechanisms involved in this protection. Mice were anesthetized with pentobarbital and subjected to 30 min of left renal ischemia after right nephrectomy, followed by exposure to 4 h of equianesthetic doses of pentobarbital or isoflurane. Five hours after renal IRI, plasma creatinine and alanine aminotransferase concentrations were measured. Liver and intestine tissues were analyzed for proinflammatory messenger RNA (mRNA) concentrations, histologic features, sphingosine kinase-1 (SK1) immunoblotting, SK1 activity, and sphingosine-1-phosphate concentrations. Renal IRI with pentobarbital led to severe renal, hepatic, and intestinal injury with focused periportal hepatocyte vacuolization; small-intestinal apoptosis; and proinflammatory mRNA up-regulation. Isoflurane protected against renal IRI and reduced hepatic and intestinal injury via induction of small-intestinal crypt SK1 mRNA, protein and enzyme activity, and increased sphingosine-1-phosphate. We confirmed the importance of SK1 because mice treated with a selective SK inhibitor or mice deficient in the SK1 enzyme were not protected against hepatic and intestinal dysfunction with isoflurane. Isoflurane protects against multiorgan injury after renal IRI via induction of the SK1/sphingosine-1-phosphate pathway. Our findings may help to unravel the cellular signaling pathways of volatile anesthetic-mediated hepatic and intestinal protection and may lead to new therapeutic applications of volatile anesthetics during the perioperative period.

Subcellular localization and distribution of the reduced folate carrier in normal rat tissues

The reduced folate carrier (Rfc1; Slc19a1) mediated transport of reduced folates and antifolate drugs such as methotrexate (MTX) play an essential role in physiological folate homeostasis and MTX cancer chemotherapy. As no systematic reports are as yet available correlating Rfc1 gene expression and protein levels in all tissues crucial for folate and antifolate uptake, storage or elimination, we investigated gene and protein expression of rat Rfc1 (rRfc1) in selected tissues. This included the generation of a specific anti-rRfc1 antibody. Rabbits were immunised with isolated rRfc1 peptides producing specific anti-rRfc1 antiserum targeted to the intracellular C-terminus of the carrier. Using RT-PCR analysis, high rRfc1 transcript levels were detected in colon, kidney, brain, thymus, and spleen. Moderate rRfc1 gene expression was observed in small intestine, liver, bone marrow, lung, and testes whereas transcript levels were negligible in heart, skeletal muscle or leukocytes. Immunohistochemical analyses revealed strong carrier expression in the apical membrane of tunica mucosa epithelial cells of small intestine and colon, in the brush-border membrane of choroid plexus epithelial cells or in endothelial cells of small vessels in brain and heart. Additionally, high rRfc1 protein levels were localized in the basolateral membrane of renal tubular epithelial cells, in the plasma membrane of periportal hepatocytes, and sertoli cells of the testes. Taken together, our results demonstrated that rRfc1 is expressed almost ubiquitously but to very different levels. The predominant tissue distribution supports the essential role of Rfc1 in physiological folate homeostasis. Moreover, our results may contribute to understand antifolate pharmacokinetics and selected organ toxicity associated with MTX chemotherapy.

Hepatomas with activating Ctnnb1 mutations in ‘ Ctnnb1 -deficient’ livers: a tricky aspect of a conditional knockout mouse model

Conditional knockout mice, based on the Cre-loxP system, are a widely used model for examining organ-specific gene functions. To date, efficient hepatocyte-specific knockout has been reported in many different models, but little attention has been paid to the long-term stability of the recombination efficiency. In the present study, we characterized Alb-Cre;Ctnnb1flox/flox 'hepatocyte-specific Ctnnb1 knockout' mice of different ages to test whether efficient recombination is maintained over time. At 2 months of age, the knockout mouse livers achieved efficient deletions of β-catenin in hepatocytes. However, as the mice aged, the reappearance and expansion of β-catenin-expressing hepatocytes were observed. In 1-year-old mice, a significant proportion of the pericentral hepatocytes in the knockout mouse livers were replaced with β-catenin-positive hepatocytes, whereas the periportal hepatocytes mostly remained β-catenin-negative. Furthermore, most of the 1-year-old mice spontaneously developed hepatocellular adenomas and carcinomas that were positive for β-catenin and overexpressed glutamine synthetase and Slc1a2, both of which are hallmarks of active β-catenin signaling. Sequencing analysis revealed that the Ctnnb1 alleles were not inactivated but had activating mutations in these tumors. The present study suggests that recombination efficiency should be carefully examined when hepatocyte-specific knockout mice of different ages are analyzed. In addition, illegitimate deletion mutations should be recognized as potential adverse effects of the Cre-loxP system.

Diagnosis and treatment of urea cycle disorders

Urea cycle disorders (UCDs) comprise a group of inherited defects of metabolism affecting the detoxification of excess nitrogen and, hereby, leading to hyperammonemia. The urea cycle consists of six consecutive enzymatic steps and is located both in the mitochondria and cytosol of periportal hepatocytes. In addition, two transporters are required for the urea cycle function. Besides the detoxification of excess nitrogen, the endogenous synthesis of the amino acid arginine is the second role of the urea cycle. The clinical presentation of UCDs comprises a continuum ranging from early onset hyperammonemic decompensation in severe defects to late onset presentation in less severe affected patients at any age. Since ammonia is primarily toxic to the central nervous system, signs and symptoms of UCDs are mainly neurological but, unfortunately, highly unspecific. Therefore, it can be challenging to clinically diagnose patients suffering from UCDs. If a UCD is suspected, ammonia should be measured immediately. To confirm the diagnosis, a variety of biochemical, enzymatic and genetic tools exist. Most UCD patients need a strict treatment protocol consisting of dietary protein restriction, nitrogen scavenger drugs, and vitamin and amino acid supplementations. Treatment must be followed lifelong unless liver transplantation is performed. Patients with UCDs are still affected by a poor outcome quoad vitam et sanitam. To improve both survival rates as well as the quality of life in surviving patients will largely depend on an increased awareness of all medical professionals towards this group of inherited metabolic defects.

Cytokines induce small intestine and liver injury after renal ischemia or nephrectomy

Patients with acute kidney injury (AKI) frequently suffer from extra-renal complications including hepatic dysfunction and systemic inflammation. We aimed to determine the mechanisms of AKI-induced hepatic dysfunction and systemic inflammation. Mice subjected to AKI (renal ischemia reperfusion (IR) or nephrectomy) rapidly developed acute hepatic dysfunction and suffered significantly worse hepatic IR injury. After AKI, rapid peri-portal hepatocyte necrosis, vacuolization, neutrophil infiltration and pro-inflammatory mRNA upregulation were observed suggesting an intestinal source of hepatic injury. Small intestine histology after AKI showed profound villous lacteal capillary endothelial apoptosis, disruption of vascular permeability and epithelial necrosis. After ischemic or non-ischemic AKI, plasma TNF-α, IL-17A and IL-6 increased significantly. Small intestine appears to be the source of IL-17A, as IL-17A levels were higher in the portal circulation and small intestine compared with the levels measured from the systemic circulation and liver. Wild-type mice treated with neutralizing antibodies against TNF-α, IL-17A or IL-6 or mice deficient in TNF-α, IL-17A, IL-17A receptor or IL-6 were protected against hepatic and small intestine injury because of ischemic or non-ischemic AKI. For the first time, we implicate the increased release of IL-17A from small intestine together with induction of TNF-α and IL-6 as a cause of small intestine and liver injury after ischemic or non-ischemic AKI. Modulation of the inflammatory response and cytokine release in the small intestine after AKI may have important therapeutic implications in reducing complications arising from AKI.

Expression of hepatocytic- and biliary-specific transcription factors in regenerating bile ducts during hepatocyte-to-biliary epithelial cell transdifferentiation

BackgroundUnder compromised biliary regeneration, transdifferentiation of hepatocytes into biliary epithelial cells (BEC) has been previously observed in rats, upon exposure to BEC-specific toxicant methylene dianiline (DAPM) followed by bile duct ligation (BDL), and in patients with chronic biliary liver disease. However, mechanisms promoting such transdifferentiation are not fully understood. In the present study, acquisition of biliary specific transcription factors by hepatocytes leading to reprogramming of BEC-specific cellular profile was investigated as a potential mechanism of transdifferentiation in two different models of compromised biliary regeneration in rats.ResultsIn addition to previously examined DAPM + BDL model, an experimental model resembling chronic biliary damage was established by repeated administration of DAPM. Hepatocyte to BEC transdifferentiation was tracked using dipetidyl dipeptidase IV (DDPIV) chimeric rats that normally carry DPPIV only in hepatocytes. Following DAPM treatment, ~20% BEC population turned DPPIV-positive, indicating that they are derived from DPPIV-positive hepatocytes. New ductules emerging after DAPM + BDL and repeated DAPM exposure expressed hepatocyte-associated transcription factor hepatocyte nuclear factor (HNF) 4α and biliary specific transcription factor HNF1β. In addition, periportal hepatocytes expressed biliary marker CK19 suggesting periportal hepatocytes as a potential source of transdifferentiating cells. Although TGFβ1 was induced, there was no considerable reduction in periportal HNF6 expression, as observed during embryonic biliary development.ConclusionsTaken together, these findings indicate that gradual loss of HNF4α and acquisition of HNF1β by hepatocytes, as well as increase in TGFβ1 expression in periportal region, appear to be the underlying mechanisms of hepatocyte-to-BEC transdifferentiation.

Isoflurane activates intestinal sphingosine kinase to protect against bilateral nephrectomy-induced liver and intestine dysfunction.

Acute kidney injury (AKI) frequently leads to systemic inflammation and extrarenal organ dysfunction. Volatile anesthetics are potent anti-inflammatory agents and protect against renal ischemia-reperfusion injury. Here, we sought to determine whether isoflurane, a commonly used volatile anesthetic, protects against AKI-induced liver and intestinal injury, the mechanisms involved in this protection, and whether this protection was independent of the degree of renal injury. Bilateral nephrectomy-induced AKI under pentobarbital sodium anesthesia led to severe hepatic and intestinal injury with periportal hepatocyte vacuolization, small intestinal necrosis, apoptosis, and proinflammatory mRNA upregulation. In contrast, isoflurane anesthesia reduced hepatic and intestinal injury after bilateral nephrectomy. Mechanistically, isoflurane anesthesia upregulated and induced small intestinal crypt sphingosine kinase-1 (SK1) as SK1 mRNA, protein, and enzyme activity increased with isoflurane treatment. Furthermore, isoflurane failed to protect mice treated with a selective SK inhibitor (SKI-II) or mice deficient in the SK1 enzyme against hepatic and intestinal dysfunction after bilateral nephrectomy, demonstrating the key role of SK1. Therefore, in addition to its potent anesthetic properties, isoflurane protects against AKI-induced liver and intestine injury via activation of small intestinal SK1 independently of the effects on the kidney. These findings may help to elucidate the cellular signaling pathways underlying volatile anesthetic-mediated hepatic and intestinal protection and result in novel clinical applications of volatile anesthetics to attenuate perioperative complications arising from AKI.

Norepinephrine modulates the zonally different hepatocyte proliferation through the regulation of transglutaminase activity

A neurotransmitter, norepinephrine (NE), amplifies the mitogenic effect of epidermal growth factor (EGF) in the liver by acting on the alpha(1)-adrenergic receptor coupled with G protein, Galpha(h). However, the molecular mechanism is not well understood. Galpha(h) is known as a transglutaminase 2 (TG2), a cross-linking enzyme implicated in hepatocyte proliferation. We investigated the effect of NE on EGF-induced cell proliferation and TG2 activity using hepatocytes isolated in periportal and perivenous regions of the liver, which differ in proliferative capacity. Periportal hepatocytes (PPH) and perivenous hepatocytes (PVH) were isolated by the digitonin-collagenase perfusion technique. EGF or NE receptor binding was analyzed by Scatchard analysis. Changes in NE-induced DNA synthesis, EGF receptor (EGFR) dimerization and phosphorylation, and TG2 activity were measured. NE enhanced EGF-induced DNA synthesis, EGF-induced EGFR dimerization, and its phosphorylation in PVH but not in PPH. [(3)H]NE binding studies indicated that PVH was found to have a greater affinity and number of receptors than PPH. Furthermore, NE treatment decreased TG2 activity and increased phospholipase C activity in PVH although TG2 level showed no change. These results suggest that NE-induced amplification of EGF-induced DNA synthesis especially in PVH is caused by upregulation of EGFR activation through the switching of function from TG2 to Galpha(h).

X-Radiation-Induced Down-Regulation of the EGF Receptor in Primary Cultured Rat Hepatocytes

Exposure to X radiation is associated with a decline in the proliferative activity of the liver, but the molecular mechanism(s) is not well understood. We investigated whether exposure to X radiation is involved in functional changes in the epidermal growth factor (EGF) receptor (EGFR), thereby causing a reduction of EGF-induced DNA synthesis using periportal hepatocytes (PPH) and perivenous hepatocytes (PVH), which differ in their proliferative activity. X radiation dose-dependently decreased DNA synthesis in both subpopulations. The rate of decline in the DNA synthesis was greater in PPH than in PVH, but the zonal difference disappeared after exposure to 10 Gy X radiation. [(125)I]EGF binding studies indicated that high-affinity EGFRs in both subpopulations were down-regulated after X irradiation. Furthermore, EGF-induced EGFR dimerization and phosphorylation at Y1173 in both subpopulations were down-regulated after X irradiation, and the rate of decline was greater in PPH than in PVH. In contrast, phosphorylation at Y845 after EGF treatment was dose-dependently up-regulated after X irradiation in both subpopulations. These results suggest that the X-radiation-related decline in EGF-induced DNA synthesis is caused at least partly by the modification of EGFR function.

Paneth cell activation after acute kidney injury causes liver and intestine injury and systemic inflammation in mice (35.9)

Abstract Patients who develop acute kidney injury (AKI) frequently suffer from extra-renal organ dysfunction and systemic inflammation syndrome. We aimed to determine the mechanisms of ischemic and non-ischemic AKI induced systemic complications. C57BL/6 mice were subjected to sham surgery, 20 min renal ischemia or unilateral nephrectomy. In addition to plasma Cr, plasma ALT markedly increased 5 hrs after both ischemic and non-ischemic AKI. These rises were correlated with peri-portal hepatocyte necrosis, vacuolization, neutrophil infiltration and pro-inflammatory mRNA upregulation. Plasma levels of TNF-α and IL-17 were also elevated after AKI. Small intestine histology after AKI showed massive epithelial necrosis and apoptosis as well as profound endothelial apoptosis. Neutralization or genetic deletion of TNF-α or IL-17 prevented AKI induced hepatic and intestine injury. Remarkable hyperplasia and degranulation of Paneth cells were observed. Laser capture microscopy of Paneth cells showed significant TNF-α and IL-17 mRNA induction after ischemic or non-ischemic AKI. Finally, Paneth cell depletion with dithizone prevented both hepatic and intestinal injury after AKI. Taken together, we propose that Paneth cell activation/degranulation after AKI produces systemic inflammation and hepatic damage via cytokine induction and intestinal barrier dysfunction. Modulating Paneth cell dysregulation may have important therapeutic implications in reducing systemic complications arising from AKI.

Novel assessment of hepatic iron distribution by synchrotron radiation X-ray fluorescence microscopy

Excess iron deposition in the liver is known to be hepatotoxic and may exacerbate liver injury. However, little is known about iron distribution in the lobule because of the lack of a highly sensitive detection method. The aim of this study is to determine iron distribution in the lobule of human liver by means of synchrotron radiation X-ray fluorescence (SRXRF) microscopy. Mapping of the trace elements was done with use of SRXRF microscopy and compared with the results of staining by Berlin blue and oxidative stress markers. Iron deposits were distributed predominantly in periportal hepatocytes in the normal liver in a decreasing gradient from the periportal area to the perivenous area. This distribution was consistent with the formation of oxidative stress markers, suggesting that hepatocytes in the periportal area may be predominantly primed by iron-induced free radical damage even in normal liver. On the other hand, iron deposits in the periportal area were more intense than those in the centrilobular area in both the liver with chronic hepatitis C and the cirrhotic liver. In conclusion, elemental mapping by SRXRF microscopy was a highly sensitive method for the detection and mapping of elements such as iron and copper in liver sections.

Histological findings in the livers of patients with neonatal intrahepatic cholestasis caused by citrin deficiency

To characterize the histological features of the livers of patients with neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD), we studied specimens from 30 patients diagnosed with NICCD by genetically analyzing the SLC25A13 gene. Liver biopsy specimens were subjected to hematoxylin-eosin, Azan, and Berlin-blue staining. Most specimens showed varying degrees of fibrosis. The degree of inflammation varied among the specimens, with half showing moderate or severe inflammatory changes. Fat deposition in hepatocytes was observed in almost all of the specimens, and severe fatty liver was noted in 20 (67%) of them. There was a mixture of two types of hepatocytes with macrovesicular or microvesicular fat droplets, and cholestasis was observed at a rate of 77%. Hemosiderin deposition, mostly mild and localized in periportal hepatocytes and macrophages in portal areas, was observed in 57% of the specimens. A combination of mixed macrovesicular and microvesicular fatty hepatocytes and the above-described findings, such as fatty liver, cholestasis, necroinflammatory reaction and iron deposition, are almost never observed in other liver diseases in infants and adults. We believe that NICCD is a disease with characteristic hepatopathological features.

Caspase inhibition in liver transplantation: from basic research to clinical studies

Caspase inhibition in liver transplantation: from basic research to clinical studies