Immunohistochemical analyses of the kinetics and distribution of macrophages, hepatic stellate cells and bile duct epithelia in the developing rat liver

Immunophenotypic analysis of the distribution of hepatic macrophages, lymphocytes and hepatic stellate cells in the adult rat liver

The liver consists of parenchymal hepatocytes and non-parenchymal cells. Non-parenchymal cells, Kupffer cells, hepatic stellate cells and cholangiocytes have crucial roles in liver homeostasis and liver pathology. To establish baseline data, this study investigated immunohistochemically the distribution of non-parenchymal cells in perivenular areas (PV), periportal areas (PP) and Glisson's sheath (GS) of adult rat liver. Liver tissues were collected from the left lateral lobe of rats. CD163-positive macrophages were seen along the sinusoid of PV and PP areas, indicating Kupffer cells. Double immunofluorescence showed, Kupffer cells partly co-expressed CD68 and MHC class II antigens in the liver. The numbers of Kupffer cells were significantly high in PP areas as compared with PV or GS areas. CD68-positive exudative macrophages were highly localized in PP and GS areas and a comparatively low PV area. MHC class II-positive dendritic cells (activated macrophages) were localized mainly in GS. Granzyme B-positive NK cells were mainly localized in the Glisson's sheath. CD3-positive T cells and CD20-positive B cells were distributed along the sinusoids of the PP and PV areas of hepatic lobules. Vimentin and glial fibrillary acidic protein (GFAP)-positive hepatic stellate cells were localized along sinusoids in the hepatic lobules of the liver. Cholangiocytes reacting to cytokeratin 19 were seen on interlobular bile ducts in Glisson's sheath of the liver. This study shows that heterogeneous macrophage populations, liver-resident lymphocytes and hepatic stellate cells localized in PP and PV areas or GS areas of the liver with cells specific patterns.

Acetaminophen-Induced Rat Hepatotoxicity Based on M1/M2-Macrophage Polarization, in Possible Relation to Damage-Associated Molecular Patterns and Autophagy

Overdose of acetaminophen (APAP), an antipyretic drug, is an important cause of liver injury. However, the mechanism in the rat model remains undetermined. We analyzed APAP-induced hepatotoxicity using rats based on M1/M2-macrophage functions in relation to damage-associated molecular patterns (DAMPs) and autophagy. Liver samples from six-week-old rats injected with APAP (1000 mg/kg BW, ip, once) after 15 h fasting were collected at hour 10, and on days 1, 2, 3, and 5. Liver lesions consisting of coagulation necrosis and inflammation were seen in the affected centrilobular area on days 1 and 2, and then, recovered with reparative fibrosis by day 5. Liver exudative enzymes increased transiently on day 1. CD68⁺ M1-macrophages increased significantly on days 1 and 2 with increased mRNAs of M1-related cytokines such as IFN-g and TNF-α, whereas CD163⁺ M2-macrophages appeared later on days 2 and 3. Macrophages reacting to MHC class II and Iba1 showed M1-type polarization, and CD204⁺ macrophages tended to be polarized toward M2-type. At hour 10, interestingly, HMGB1 (representative DAMPs) and its related signals, TLR-9 and MyD88, as well as LC3B⁺ autophagosomes began to increase. Collectively, the pathogenesis of rat APAP hepatotoxicity, which is the first, detailed report for a rat model, might be influenced by macrophage functions of M1 type for tissue injury/inflammation and M2-type for anti-inflammatory/fibrosis; particularly, M1-type may function in relation to DAMPs and autophagy. Understanding the interplayed mechanisms would provide new insight into hepato-pathogenesis and contribute to the possible development of therapeutic strategies.

Characterization of Macrophages and Myofibroblasts Appearing in Dibutyltin Dichloride-Induced Rat Pancreatic Fibrosis

Macrophages and myofibroblasts are important in fibrogenesis. The cellular characteristics in pancreatic fibrosis remain to be investigated. Pancreatic fibrosis was induced in F344 rats by a single intravenous injection of dibutyltin dichloride. Histopathologically, the induced pancreatic fibrosis was divided into 3 grades (1+, 2+, and 3+), based on collagen deposition. Immunohistochemically, CD68-expressing M1 macrophages increased with grade and CD163-expressing M2 macrophages also increased later than M1 macrophage appearance. Double immunofluorescence showed that there were macrophages coexpressing CD68 and CD163, suggesting a possible shift from M1 to M2 types; similarly, increased major histocompatibility complex class II- and CD204-expressing macrophages were polarized toward M1 and M2 types, respectively. These findings indicated the participation of M1- and M2-polarized macrophages. Mesenchymal cells staining positive for vimentin, desmin, and α-smooth muscle actin (α-SMA) increased with grade. There were mesenchymal cells coexpressing vimentin/α-SMA, desmin/α-SMA, and glial fibrillary acidic protein (GFAP)/α-SMA; Thy-1-expressing immature mesenchymal cells also increased in fibrotic lesions. Because α-SMA expression is a reliable marker for myofibroblasts, α-SMA-expressing pancreatic myofibroblasts might be originated from GFAP-expressing pancreatic stellate cells or Thy-1-expressing immature mesenchymal cells; the myofibroblasts could simultaneously express cytoskeletal proteins such as vimentin and desmin. The present findings would provide useful information for analyses based on features of macrophages and myofibroblasts in chemically induced pancreatic fibrosis.

Expression of Genes Encoding for Xenobiotic Metabolism After Exposure to Dialkylnitrosamines in the Chicken Egg Genotoxicity Alternative Model

The Chicken Egg Genotoxicity Assay (CEGA) demonstrated responsiveness to various DNA-reactive chemicals requiring metabolic activation, which implies broad bioactivation capability. To assess potential metabolic competence, expression profiles of metabolic genes in the embryo-chicken fetal liver were determined using microarray technology. Fertilized chicken eggs were injected under the CEGA protocol with vehicle (deionized water [DW]), the activation-dependent carcinogens, diethylnitrosamine (DEN), and N-nitrosodiethanolamine (NDELA) at doses producing no effect on survival. Previously in CEGA, DEN produced DNA damage, whereas NDELA did not. Expressions of 463 genes known to encode for phase I and II of endo- and xenobiotic metabolism were detected on the array. DW did not affect the expression of the selected genes, deregulating less than 1% of them. In contrast, DEN at 2 mg/egg and NDELA at 4 mg/egg produced significant transcriptomic alterations, up-regulating up to 41% and down-regulating over 31% of studied genes. Both nitrosamines modulated the majority of the genes in a similar manner, sharing 64 up-regulated and 93 down-regulated genes with respect to control group, indicating similarity in the regulation of their metabolism by avian liver. Differences in gene expression between DEN and NDELA were documented for several phase I CYP 450 genes that are responsible for nitrosamine biotransformation, as well as for phase II genes that regulate detoxication reactions. These findings could underlie the difference in genotoxicity of DEN and NDELA in CEGA. In conclusion, the analysis of gene expression profiles in embryo-chicken fetal liver dosed with dialkylnitrosamines demonstrated that avian species possess a complex array of inducible genes coding for biotransformation.

Immunohistochemical characterization of myofibroblasts appearing in isoproterenol-induced rat myocardial fibrosis

Fibrotic lesion is formed by myofibroblasts capable of producing collagens. The myofibroblasts are characterized by immunoexpressions of vimentin, desmin and α-smooth muscle actin (α-SMA) in varying degrees. The cellular characteristics remain investigated in myocardial fibrosis. We analyzed immunophenotypes of myofibroblasts appearing in isoproterenol-induced myocardial fibrosis in rats until 28 days after injection (10 mg/kg body weight); the lesions developed as interstitial edema and inflammatory cell reaction on 8 hr and days 1 and 3, and fibrosis occurred on days 1, 3, 7, 14, and 21 by gradual deposition of collagens, showing the greatest grade on day 14; the lesions gradually reduced with sporadic scar until day 28. Myofibroblasts expressing vimentin and α-SMA increased with a peak on day 3, and then, gradually decreased onwards. Interestingly, Thy-1 expressing cells appeared in the affected areas, apparently being corresponding to the grade similar to vimentin- and α-SMA-positive cells. Thy-1 is expressed in immature mesenchymal cells such as pericytes with pluripotent nature. The immunoreactivity for A3-antigen, a marker for immature mesenchymal cells, was seen in some surrounding cells. There were no cells reacting with antibodies to nestin or glial fibrillary acidic protein, although hepatic myofibroblats have been reported to react with these antibodies. Collectively, myofibroblasts appearing in rat myocardial fibrosis may have been derived from immature mesenchymal cells positive for Thy-1 or A3-antigen, with thereafter showing expressions of vimentin and α-SMA in differentiation.

Immunohistochemical analyses of the kinetics and distribution of macrophages in the developing rat kidney

Macrophages are required during kidney development and appear in the initiation and propagation of renal injury. To establish baseline data, we analyzed the kinetics of the macrophage with different immunophenotypes in the developing rat kidney (fetus at 18 and 20 days, neonate at 1-21 days, and adult at 7-weeks old). Macrophages reacting to CD68, CD163, and MHC class II were identified in the cortex and medulla of the developing rat kidney. CD68+ macrophages appeared in the fetal kidney as early as fetal day 18, and the number increased gradually in the neonatal kidney, whereas MHC class II+ and CD163+ macrophages first appeared on neonatal days 4 and 8, respectively. Apoptotic bodies were seen in the fetal kidney and early stages of the neonatal kidney (days 1-4), and simultaneously CD68+ macrophages appeared, indicating that CD68+ macrophages may have roles in phagocytosis of apoptotic bodies and contribute to renal tissue maturation. Colony stimulating factor 1 and insulin growth factor 1 mRNAs were increased in the late stage of renal development (neonatal day 12 or later), and simultaneously CD163+ and MHC class II+ cells appeared, suggesting that these cells may be a source of these growth factors and participate in renal tissue modeling. Generally, the CD163+ and MHC class II+ cell number was much smaller than that of CD68+ cells in the developing neonatal kidney. Therefore, the obtained findings provide valuable information on the participation of macrophages in the developing rat kidney. This information may be useful for evaluation of renal toxicity when macrophages are involved in the development of renal injury.

Macrophage Populations and Expression of Regulatory Inflammatory Factors in Hepatic Macrophage-depleted Rat Livers under Lipopolysaccharide (LPS) Treatment

To investigate the significance of the appearance of hepatic macrophages and expression of inflammatory factors in normal and macrophage-depleted livers, hepatic macrophages were depleted with liposome (Lipo)-encapsulated clodronate (CLD; 50 mg/kg, i.v.) followed by lipopolysaccharide (LPS) administration (0.1 mg/kg, i.p.) in F344 rats (CLD + LPS). Vehicle control rats (Lipo + LPS) received empty-Lipo before LPS. The low dose of LPS did not result in microscopic changes in the liver in either treatment group but did modulate M1 and M2 macrophage activity in Lipo + LPS rats without altering repopulating hepatic macrophages in CLD + LPS rats. LPS treatment in Lipo + LPS rats dramatically increased the M1 (IL-1β, IL-6, TNF-α, and MCP-1) but not M2 macrophage-related factors (IL-4 and CSF-1) compared to CLD + LPS rats. In the CLD + LPS rats, the M2 macrophage-related factors IL-4 and CSF-1 were elevated. In conclusion, low-dose LPS activated hepatic macrophages in rat livers without causing liver injury or stimulating repopulating hepatic macrophages. These data suggest that LPS may alter the liver microenvironment by modulating M1 or M2 macrophage-related inflammatory mediators and macrophage-based hepatotoxicity.

Immunophenotypical analysis of pancreatic interstitial cells in the developing rat pancreas and myofibroblasts in the fibrotic pancreas in dogs and cats

Pancreatic fibrosis develops as the results of the activity of myofibroblasts capable of producing collagens. The myofibroblasts derive from pancreatic interstitial cells, including pancreatic stellate cells (PSCs), which can express glial fibrillary acidic protein (GFAP). First, we investigated the expression patterns of vimentin, desmin, α-smooth muscle actin (α-SMA), Thy-1 and GFAP in the developing rat pancreas (in fetuses at 18 and 20 days, neonates from 1 to 21 days, and adults). Interstitial cells in the developing pancreas expressed vimentin, desmin, GFAP and Thy-1 at varying degrees; interestingly, the reactivity for desmin and vimentin was the highest in fetuses. GFAP expression was consistent between fetuses and neonates, and Thy-1 reactivity transiently increased after birth; however, α-SMA-positive interstitial cells were rarely seen. Next, we analyzed the immunophenotypical characteristics of myofibroblasts appearing in pancreatic fibrosis in dogs and cats. With increasing fibrotic grade, myofibroblasts showed increased expression of vimentin, desmin and α-SMA, in addition to increased GFAP expression. Collectively, pancreatic interstitial cells and myofibroblasts may have similar immunophenotypes, and myofibroblasts might originate partly from GFAP-expressing PSCs.

Attenuation of alpha-naphthylisothiocyanate (ANIT)-induced biliary fibrosis by depletion of hepatic macrophages in rats

Biliary fibrosis is a complex process in which macrophages and myofibroblasts may play central roles. We investigated biliary fibrosis lesions induced in the Glisson's sheath in rats by alpha-naphthylisothiocyanate (ANIT) administration under macrophage depletion. Hepatic macrophages were depleted in F344 rats with liposome-encapsulated clodronate (CLD) (10mL/kg body weight, i.v) followed by bile duct injury with ANIT (75mg/kg body weight, i.p) (ANIT+CLD group). Rats received empty-liposomes (Lipo) followed by ANIT, and served as control (ANIT+Lipo group). In both ANIT+Lipo and ANIT+CLD groups, ANIT-induced bile duct injury with inflammatory cell infiltration was seen on days 1-3, and subsequently reparative fibrosis occurred on days 5 and 7. In comparisons between the two groups, macrophages reacting to CD68, CD163, MHC class II and CD204 were less in numbers in ANIT+CLD group; the most sensitive immunophenotype was of CD163-positive. Furthermore, in ANIT+CLD group interstitial mesenchymal cells/myofibroblasts reacting to vimentin, desmin and α-smooth muscle actin were also less in grades and tended to be delayed in appearance. Interestingly, MCP-1, IFN-γ, IL-10, and TGF-β1 mRNAs were significantly increased mainly on day 2 in ANIT+Lipo group, while the levels of these factors were prominently lower in ANIT+CLD group. Collectively, depletion of hepatic macrophages plays roles in attenuating biliary fibrogenesis by production of inflammatory factors. The present results indicated clearly importance of macrophage functions in the pathogenesis of biliary fibrosis.

Depletion of Hepatic Macrophages Aggravates Liver Lesions Induced in Rats by Thioacetamide (TAA)

Hepatic macrophages play crucial roles in hepatotoxicity. We investigated immunophenotypes of macrophages in liver injury induced in rats by thioacetamide (TAA; 300 mg/kg, intraperitoneal) after hepatic macrophage depletion; hepatic macrophages were depleted by liposomal clodronate (CLD; 10 ml/kg, i.v.) one day before TAA injection. Samples were obtained on post-TAA injection days 0, 1, 2, 3, 5, and 7. TAA injection induced coagulation necrosis of hepatocytes on days 1 through 3 and subsequent reparative fibrosis on days 5 and 7 in the centrilobular area, accompanied by increased numbers of M1 macrophages (expressing cluster of differentiation [CD]68 and major histocompatibility complex class II) and M2 macrophages (expressing CD163 and CD204) mainly on days 1 through 3. TAA + CLD treatment markedly decreased the numbers of M1 and M2 macrophages mainly on days 1 through 3; CD163(+) Kupffer cells were most sensitive to CLD depletion. In TAA + CLD-treated rats, interestingly, coagulation necrosis of hepatocytes was prolonged with more increased levels of hepatic enzymes (aspartate transaminase, alanine transaminase, and alkaline phosphatase) to TAA-treated rats; reparative fibrosis was incomplete and replaced by dystrophic calcification in the injured area, indicating the aggravated damage. Furthermore, in TAA + CLD-treated rats, inflammatory factors (monocyte chemoattractant protein [MCP]-1, interferon-γ, tumor necrosis factor-α, and interleukin-10) and fibrosis-related factors (transforming growth factor-β1, matrix metalloproteinase-2, tissue inhibitor of metalloproteinase-1) were decreased at messenger RNA levels, indicating abnormal macrophage functions. It was clearly demonstrated that hepatic macrophages have important roles in tissue damage and remodeling in hepatotoxicity.

Histopathological Analysis of Rat Hepatotoxicity Based on Macrophage Functions: in Particular, an Analysis for Thioacetamide-induced Hepatic Lesions

Hepatic macrophages play an important role in homeostasis. The functional abnormalities of hepatic macrophages primarily or secondarily influence chemically induced hepatotoxicity. However, the evaluation system based on their functions has not yet been established. Recently, a new concept (M1-/M2-macrophage polarization) was proposed; M1-macropahges are induced by INF-γ, and show high phagocytosis/tissue damage, whereas M2-macropahges are induced by IL-4 and play roles in reparative fibrosis by releasing IL-10 and TGF-β1. In hepatogenesis, CD68-expressing M1-macrophages predominantly exist in embryos; in neonates, in contrast, CD163-/CD204-expressing M2-macrophages appear along the sinusoids and mature as Kupffer cells. Activated Kupffer cells by liposome decrease AST and ALT values, whereas AST and ALT values are increased under Kupffer cells depleted with clodronate treatment. Since Kupffer cells may be involved in clearance of liver enzymes, macrophage condition should be taken into consideration when hepatotoxicity is analyzed. In TAA-induced acute hepatic lesions, INF-γ, TNF-α and IL-6 for M1-factors and IL-4 for M2-factors are already increased before histopathological change; the appearance of CD68-expressing M1-macrophages and CD163-expressing M2-macrophages follows in injured centrilobular lesions, and TGF-β1 and IL-10 are increased for reparative fibrosis. CD68-expressing M1-macrophages co-express MHC class II and Iba-1, whereas CD163-expressing M2-macrophages also express CD204 and Galectin-3. Under macrophage depletion by clodoronate, TAA-treated rat livers show prolonged coagulation necrosis of hepatocytes, and then develop dystrophic calcification without reparative fibrosis. The depletion of hepatic macrophages influences hepatic lesion development. Collectively, a histopathological analysis method for hepatotoxicity according to M1-/M2-macrophage polarization would lead to the refinement of hazard characterization of chemicals in food and feed.

Transient effects of empty liposomes on hepatic macrophage populations in rats

Liposomes have been used as a vehicle for encapsulating chemicals or toxins in toxicological studies. We investigated the transient effects of empty liposomes on hepatic macrophages by applying a single intravenous injection at a dose of 10 ml/kg body weight in 6-week-old male F344 rats. One day after injection, the numbers of hepatic macrophages reacting to CD163, CD68, Iba-1, MHC class II, Gal-3 and CD204 were significantly increased in liposome-treated rats. CD163⁺ Kupffer cells and CD68⁺ macrophages with increased phagocytic activity in hepatic lobules were most sensitive. The histological architecture of the liver was not changed following liposome injection; however, hepatocytes showed increased proliferating activity, demonstrable with proliferation marker immunostaining and by an increase in gene profiles related to the cell cycle. In the liposome-treated rats, interestingly, AST and ALT values were significantly decreased, and MCP-1, IL-1β and TGF-β1 mRNAs were significantly increased. Collectively, the present study found that hepatic macrophages activated by liposomes can influence liver homeostasis. This information would be useful for background studies on liposomes.

Immunophenotypical characterization and influence on liver homeostasis of depleting and repopulating hepatic macrophages in rats injected with clodronate

Hepatic macrophages (including Kupffer cells) play a crucial role in the homeostasis and act as mediators of inflammatory response in the liver. Hepatic macrophages were depleted in male F344 rats by a single intravenous injection of liposomal clodronate (CLD; 50mg/kg body weight), and immunophenotypical characteristics of depleting and repopulating macrophages were analyzed by different antibodies specific for macrophages. CD163(+) Kupffer cells were almost completely depleted on post-injection (PI) days 1-12. Macrophages reacting to CD68, Iba-1, and Gal-3 were drastically reduced in number on PI day 1 and then recovered gradually until PI day 12. MHC class II(+) and CD204(+) macrophages were moderately decreased during the observation period. Although hepatic macrophages detectable by different antibodies were reduced in varying degrees, Kupffer cells were the most susceptible to CLD. Liver situation influenced by depleted hepatic macrophages was also investigated. No marked histological changes were seen in the liver, but the proliferating activity of hepatocytes was significantly increased, supported by changes of gene profiles relating to cell proliferation on microarray analysis on PI day 1; the values of AST and ALT were significantly elevated; macrophage induction/activation factors (such as MCP-1, CSF-1, IL-6 and IL-4) were increased exclusively on PI day 1, whereas anti-inflammatory factors such as IL-10 and TGF-β1 remained significantly decreased after macrophage depletion. The present study confirmed importance of hepatic macrophages in liver homeostasis. The condition of hepatic macrophages should be taken into consideration when chemicals capable of inhibiting macrophage functions are evaluated.

The development of hepatic stellate cells in normal and abnormal human fetuses - an immunohistochemical study

The precise embryological origin and development of hepatic stellate cells is not established. Animal studies and observations on human fetuses suggest that they derive from posterior mesodermal cells that migrate via the septum transversum and developing diaphragm to form submesothelial cells beneath the liver capsule, which give rise to mesenchymal cells including hepatic stellate cells. However, it is unclear if these are similar to hepatic stellate cells in adults or if this is the only source of stellate cells. We have studied hepatic stellate cells by immunohistochemistry, in developing human liver from autopsies of fetuses with and without malformations and growth restriction, using cellular Retinol Binding Protein-1 (cRBP-1), Glial Fibrillary Acidic Protein (GFAP), and α-Smooth Muscle Actin (αSMA) antibodies, to identify factors that influence their development. We found that hepatic stellate cells expressing cRBP-1 are present from the end of the first trimester of gestation and reduce in density throughout gestation. They appear abnormally formed and variably reduced in number in fetuses with abnormal mesothelial Wilms Tumor 1 (WT1) function, diaphragmatic hernia and in ectopic liver nodules without mesothelium. Stellate cells showed similarities to intravascular cells and their presence in a fetus with diaphragm agenesis suggests they may be derived from circulating stem cells. Our observations suggest circulating stem cells as well as mesothelium can give rise to hepatic stellate cells, and that they require normal mesothelial function for their development.

Understanding the Mysterious M2 Macrophage through Activation Markers and Effector Mechanisms

The alternatively activated or M2 macrophages are immune cells with high phenotypic heterogeneity and are governing functions at the interface of immunity, tissue homeostasis, metabolism, and endocrine signaling. Today the M2 macrophages are identified based on the expression pattern of a set of M2 markers. These markers are transmembrane glycoproteins, scavenger receptors, enzymes, growth factors, hormones, cytokines, and cytokine receptors with diverse and often yet unexplored functions. This review discusses whether these M2 markers can be reliably used to identify M2 macrophages and define their functional subdivisions. Also, it provides an update on the novel signals of the tissue environment and the neuroendocrine system which shape the M2 activation. The possible evolutionary roots of the M2 macrophage functions are also discussed.

Expression of nestin in remodelling of α-naphthylisothiocyanate-induced acute bile duct injury in rats

The function of the intermediate filament protein nestin is poorly understood. The significance of nestin expression was assessed in α-naphthylisothiocyanate (ANIT)-induced cholangiocyte injury lesions in F344 rats. Liver samples obtained from rats injected intraperitoneally with ANIT (75 mg/kg) on post-injection days 0 (control) and 1-12 were labelled immunohistochemically for expression of nestin and markers specific for mesenchymal cells (vimentin), hepatic stellate cells (HSCs) (desmin and glial fibrillary acidic protein [GFAP]), endothelial cells (rat endothelial cell antigen [RECA]-1), cholangiocytes (cytokeratin [CK] 19) and cellular proliferation (Ki67). Cholangiocyte injury led to infiltration of neutrophils and macrophages followed by aggregation of mesenchymal cells and regeneration of bile ducts. Nestin expression was detected in mesenchymal cells (vimentin positive) on days 1-7 with a peak on days 3-5 and in newly-formed RECA-1-positive endothelial cells on day 3. Nestin expression was also observed in regenerating CK19-positive cholangiocytes on days 2-5, with a peak on day 3. Labelling for Ki67 showed proliferation of cholangiocytes, mesenchymal cells and HSCs. Real-time reverse transcriptase polymerase chain reaction with microdissected samples showed significantly elevated nestin mRNA on day 3. The findings suggest an association between nestin expression and cellular proliferation. Based on these findings, it was considered that nestin-expressing mesenchymal cells, HSCs and endothelial cells may be possible progenitors of repopulating cholangiocytes. Nestin expression may serve as an indicator for cellular remodelling and behaviour of injured and repopulating bile ducts.

A new method to isolate and culture rat kupffer cells

BACKGROUND

Previous methods for Kupffer cells (KCs) isolation require sophisticated skills and tedious procedures. Few studies have attempted to explore the self-renewal capacity of KCs in vitro. Therefore, the aim of this study was to establish a simple method for rat KCs isolation and further investigate the mitotic potential of KCs in vitro.

METHODS

KCs were obtained by performing one-step perfusion, enzymatic tissue treatment, differential centrifugation and selective adherence. The proliferation ability of cultured KCs was determined by MTT assay and Propidium Iodide FACS analysis. Phagocytic assay and ED-1, ED-2 immunofluorescence were used to identify cell phenotype. After stimulation with LPS, the expression of surface antigens (MHCII, CD40, CD80, and CD86) and the production of cytokines (NF-κB, TNF-α, IL-6 and IL-10) were measured for cell function identification.

RESULTS

KCs were isolated with certain numbers and reasonable purities. The KCs were able to survive until at least passage 5 (P5), and at P3 showed equally strong phagocytic activity as primary KCs (P0). After stimulation with LPS, the change in the expression of surface antigens and the production of cytokines for P3 cells was similar to that for P0 cells.

CONCLUSIONS

Our study provides a simple and efficient method for KCs isolation, and reveals that self-renewing KCs have the same phagocytic activity and functions as primary KCs.

Spatial relationship between expression of cytokeratin-19 and that of connexin-43 in human fetal kidney

Connexin-43, a major gap junction protein, and cytokeratin-19, one of the intermediate filament keratins, are known to be markers of well-differentiated epithelium. In this study, we investigated the expression of these markers in the head region, lungs, and abdominal organs of 10 human mid-term fetuses. The expression of connexin-43 was found to be restricted to the dura mater, kidney, and adrenal cortex. In the kidney, we found a clear site-dependent difference in the expression pattern of these markers: connexin-43 expression was observed in the tubules of the renal cortex whereas cytokeratin-19 was strongly expressed in the collecting ducts and renal pelvis. This difference remained unchanged throughout the fetal stages examined. Immunoreactivity was not observed for either of the markers in the intrarenal vessels, including the glomeruli, and mesangial cells. Connexin-43 expression seemed to be restricted to the metanephric vesicle-derived structures that differentiate in the urogenital ridge of the splanchnic mesoderm. The adrenal cortex also originates from the same para-aortic mesoderm. In contrast, in the urogenital organs, cytokeratin-19 seemed to be expressed in ducts derived from the urogenital sinus.

The profile of β-amyloid precursor protein expression of rats induced by aluminum

The environmental agent aluminum has been extensively investigated for a potential relationship with amyloid precursor protein (APP) expression. Despite many investigations, there is at present no definite proof from which to draw a conclusion. Since APP is an integral membrane protein expressed in different tissues and capable of fluxes across the blood-brain barrier (BBB), which may ultimately affect APP level in brain, it is necessary to assess the expression profile among vital body organs. The present study compared aluminum oxide and aluminum chloride injected rats with control rats (saline treated) to observe if aluminum affected APP expression patterns in different organs by immunohistochemistry (IHC). The expression of APP was observed in the brain of aluminum chloride treated rats and in the liver of aluminum oxide injected group. Results of double IHC staining showed that it is Kupffer cells, which are located in liver sinus and expressed APP after aluminum oxide treatment. Oxidative stress is suggested as the potential pathway that aluminum chloride exert effects in brain. These results suggest that different aluminum compounds may impact the expression of APP in brain and liver tissues. The mechanism that aluminum induced liver APP expression still needs further investigation.