Dyskerin expression in human fetal, adult and neoplastic intrahepatic bile ducts: correlations with cholangiocarcinoma aggressiveness.

AIMS: To investigate the immunohistochemical expression of dyskerin, a biomarker involved in ribosome production and telomere maintenance, in human fetal, adult and neoplastic bile ducts, and possible correlations with cholangiocarcinoma aggressiveness. METHODS AND RESULTS: Sixty consecutive intrahepatic cholangiocarcinomas were collected and used for tissue microarray construction (total: 176 cores); clinical data and follow-up were also collected. Five fetal and 10 normal adult livers were included as controls. Automated immunohistochemistry for dyskerin, p53, and Ki67, and nucleolar silver staining, were performed. In normal livers, dyskerin expression was negative in smaller bile ducts (mean 44.8 µm) and positive in bile ducts of larger diameter (mean 116.1 µm; P < 0.001). Expression was positive in 56.7% of cholangiocarcinomas, and correlated with p53 mutation (P = 0.008) and a higher proliferative (Ki67) index (P = 0.003), which were included as markers of tumour aggressiveness. Finally, dyskerin-positive cholangiocarcinomas showed a negative trend in disease-free survival (P = 0.078) on univariate analysis. CONCLUSIONS: The non-neoplastic biliary tree seems to progressively lose dyskerin expression from the major branches to the peripheral portal bile ducts. Similarly, intrahepatic cholangiocarcinomas showed two patterns of dyskerin expression, and the dyskerin-positive phenotype seemed to characterize more aggressive cholangiocarcinomas.

Differential expression of perilipin 2 and 5 in human skeletal muscle during aging and their association with atrophy-related genes.

Sarcopenia, the progressive loss of muscle mass and strength, is a phenomenon characterizing human aging whose etiology is still not clear. While there is increasing evidence for the influence of inter-muscular adipose tissue infiltration in the development of sarcopenia, much less is known about a possible role for intra-muscular triglycerides (IMTG). IMTG accumulate in form of lipid droplets decorated by proteins such as Perilipins (Plins). In skeletal muscle the most abundant are Plin2 and Plin5. In this study we compared the expression of these two Plins in Vastus lateralis muscle samples of subjects of different age, both healthy donors (HD) and patients with limited lower limb mobility (LLMI). These latter are characterized by a condition of chronic physical inactivity. Plin2 expression resulted higher in old age for both HD and LLMI patients, while Plin5 slightly decreased only in LLMI patients. Moreover, in these patients, only Plin2 was associated with the decrease of muscle strength and the expression of factors related to muscle atrophy (MuRF1, Atrogin and p53). An increase in Plin2 and a concomitant decrease of Plin5 was also observed when we considered animal model of disuse-induced muscle atrophy. As a whole, these data indicate that Plin2 and Plin5 have a different expression pattern during muscle aging and inactivity, and only Plin2 appears to be associated with functional alterations of the muscle.

The role of 3D microenvironmental organization in MCF-7 epithelial-mesenchymal transition after 7 culture days.

We present a multi-technique study on in vitro epithelial-mesenchymal transition (EMT) in human MCF-7 cells cultured on electrospun scaffolds of poly(l-lactic acid) (PLA), with random and aligned fiber orientations. Our aim is to investigate the morphological and genetic characteristics induced by extracellular matrix in tumor cells cultured in different 3D environments, and at different time points. Cell vitality was assessed with AlamarBlue at days 1, 3, 5 and 7. Scanning electron microscopy was performed at culture days 3 and 7. Immunohistochemistry (for E-cadherin, ß-catenin, cytokeratins, nucleophosmin, tubulin, Ki-67 and vimentin), immunofluorescence (for F-actin) western blot (for E-cadherin, ß-catenin and vimentin) and transmission electron microscopy were carried out at day 7. An EMT gene array followed by PCR analysis confirmed the regulation of selected genes. At day 7, scanning electron microscopy on aligned-PLA revealed spindle-shaped cells gathered in buds and ribbon-like structures, with a higher nucleolar/nuclear ratio and a loss in E-cadherin and ß-catenin at immunohistochemistry and western blot. An up-regulation of SMAD2, TGF-ß2, TFPI2 and SOX10 was found in aligned-PLA compared to random-PLA cultured cells. The topography of the extracellular matrix has a role in tumor EMT, and a more aggressive phenotype characterizes MCF-7 cells cultured on aligned-PLA scaffold.

Efficacy of selective transarterial chemoembolization in inducing tumor necrosis in small (<5 cm) hepatocellular carcinomas.

UNLABELLED: Transarterial chemoembolization (TACE) is commonly used as a bridge therapy for patients awaiting liver transplantation (LT) and for downstaging patients initially not meeting the Milan criteria. The primary aim of this study was to analyze whether a difference exists between selective/superselective and lobar TACE in determining tumor necrosis by a pathological analysis of the whole lesion at the time of LT. The secondary aim was to investigate the relationship between the tumor size and the capacity of TACE to induce necrosis. Data were extracted from a prospective database of 67 consecutive patients who underwent LT for hepatocellular carcinoma and cirrhosis from 2003 to 2009 and were treated exclusively with TACE as a bridging (n = 53) or downstaging therapy (n = 14). We identified 122 nodules; 53.3% were treated with selective/superselective TACE. The mean histological necrosis level was 64.7%; complete tumor necrosis was obtained in 42.6% of the nodules. In comparison with lobar TACE, selective/superselective TACE led to significantly higher mean levels of necrosis (75.1% versus 52.8%, P = 0.002) and a higher rate of complete necrosis (53.8% versus 29.8%, P = 0.013). A significant direct relationship was observed between the tumor diameter and the mean tumor necrosis level (59.6% for lesions < 2 cm, 68.4% for lesions of 2.1-3 cm, and 76.2% for lesions > 3 cm). Histological necrosis was maximal for tumors > 3 cm: 91.8% after selective/superselective TACE and 66.5% after lobar procedures. Independent predictors of complete tumor necrosis were selective/superselective TACE (P = 0.049) and the treatment of single nodules (P = 0.008). Repeat sessions were more frequently needed for nodules treated with lobar TACE (31.6% versus 59.3%, P = 0.049). CONCLUSION: Selective/superselective TACE was more successful than lobar procedures in achieving complete histological necrosis, and TACE was more effective in 3- to 5-cm tumors than in smaller ones.

Pre-operative liver biopsy in cirrhotic patients with early hepatocellular carcinoma represents a safe and accurate diagnostic tool for tumour grading assessment.

BACKGROUND & AIMS: Knowledge of pre-operative tumour grade is crucial in the management of hepatocellular carcinoma (HCC) because it can influence recurrence and survival after surgery. The accuracy of pre-operative needle core biopsy (NCB) in tumour grading has been assessed in only a few studies with conflicting results. Our aim was to determine the long-term safety and the overall accuracy of NCB in assessing tumour grading in subjects who had undergone liver resection for a single HCC. METHODS: Eighty-one cirrhotic patients with HCC who had undergone NCB before liver resection were selected. Only patients with a single HCC and with at least a five-year-follow-up were included. Tumour grading was scored according to a modified Edmondson-Steiner classification: well/moderately (low grade) vs poorly-differentiated (high grade). RESULTS: In the 81 patients with a solitary HCC (mean size 4.1 ± 2.3cm) tumour grade was correctly identified by NCB in 74 out of 81 (91.4%) HCCs. NCB overall sensitivity and specificity were 65% and 98.1%, respectively, with a PPV of 92% and an NPV of 91%. No major complications (in particular tumour seeding) were observed. The overall survival rates at 1, 3, and 5 years were 83%, 62%, and 44%, respectively; the recurrence rate after a 5-year-follow-up was 56.2% for low grade and 82.3% for high grade tumours (p<0.007). CONCLUSIONS: Pre-operative NCB can be performed on early (<5 cm) HCC cirrhotic patients because it provides histologically useful information for HCC management with good accuracy and a low complication rate.

Studies on immunoproteasome in human liver. Part I: absence in fetuses, presence in normal subjects, and increased levels in chronic active hepatitis and cirrhosis.

Despite the central role of proteasomes in relevant physiological pathways and pathological processes, this topic is unexpectedly largely unexplored in human liver. Here we present data on the presence of proteasome and immunoproteasome in human livers from normal adults, fetuses and patients affected by major hepatic diseases such as cirrhosis and chronic active hepatitis. Immunohistochemistry for constitutive (alpha4 and beta1) and inducible (LMP2 and LMP7) proteasome subunits, and for the PA28alphabeta regulator, was performed in liver samples from 38 normal subjects, 6 fetuses, 2 pediatric cases, and 19 pathological cases (10 chronic active hepatitis and 9 cirrhosis). The immunohistochemical data have been validated and quantified by Western blotting analysis. The most striking result we found was the concomitant presence in hepatocyte cytoplasm of all healthy subjects, including the pediatric cases, of constitutive proteasome and immunoproteasome subunits, as well as PA28alphabeta. At variance, immunoproteasome was not present in hepatocytes from fetuses, while a strong cytoplasmic and nuclear positivity for LMP2 and LMP7 was found in pathological samples, directly correlated to the histopathological grade of inflammation. At variance from other organs such as the brain, immunoproteasome is present in livers from normal adult and pediatric cases, in apparent absence of pathological processes, suggesting the presence of a peculiar regulation of the proteasome/immunoproteasome system, likely related to the physiological stimuli derived from the gut microbiota after birth. Other inflammatory stimuli contribute in inducing high levels of immunoproteasome in pathological conditions, where its role deserve further attention.

Predictive value of frozen-section analysis in the histological assessment of steatosis before liver transplantation.

Histological quality assessment of donated livers is a key factor for extending the cadaveric donor pool for liver transplantation. We retrospectively compared frozen-section analysis with routine histological permanent slides and the outcomes of grafts in liver biopsies from 294 candidate donors. The kappa concordance coefficient of agreement between frozen-section analysis and routine histological analysis was very good for macrosteatosis (kappa = 0.934), microsteatosis (kappa = 0.828), and total steatosis (kappa = 0.814). The correlation between the mean amounts of macrosteatosis, microsteatosis, and total steatosis in frozen and permanent sections was also significant (P < 0.001, Spearman's test). Macrosteatosis and microsteatosis were overestimated to >30% in 4 of 32 cases (12.5%) and in 23 of 62 cases (37.1%), respectively. The only 2 histological parameters of frozen sections able to predict graft dysfunction within 7 days of transplantation were macrosteatosis and total steatosis (P = 0.018 and P = 0.015, respectively, Mann-Whitney test). None of the other histopathological features evaluated in frozen sections, including portal inflammation, lobular necrosis, myointimal thickening, biliocyte regression, cholestasis, hepatocellular polymorphism, lipofuscin storage, and fibrous septa, were significantly correlated with the graft outcome. The frozen-section histological evaluation of biopsies from cadaveric liver donors is an accurate, time-effective, and predictive method for the assessment of graft suitability.

Blood monitoring of granzyme B and perforin expression after intestinal transplantation: considerations on clinical relevance.

BACKGROUND: The use of biomarkers for rejection monitoring represents a major goal in intestinal transplantation. We analyzed the blood expression of Granzyme B (GB) and Perforin (PF) in the following pathological conditions after intestinal transplantation: acute rejection (AR), Epstein-Barr virus (EBV) and cytomegalovirus (CMV) infection, and posttransplant lymphoproliferative disease (PTLD). The diagnostic accuracy and the clinical utility of these tests are finally discussed. METHODS: GB and PF levels were measured by real time polymerase chain reaction on peripheral blood samples from 32 intestinal recipients. Blood samples (n=494) after comparison of clinical, histological, and microbiological data were assigned to the following groups: normal (n=307), AR (n=30), EBV infection (n=107), CMV infection (n=25), and PTLD (n=25). RESULTS: Mean levels of GB and PF in the AR (GB=279.7; PF=256.7), PTLD (GB=199; PF=185.9), EBV (GB=133.2; PF=143.7), and CMV (GB=151.3; PF=144) groups were significantly higher than in the normal group (GB=100.1; PF=101.1) (all P<0.05, except for PF in CMV infection). The best accuracy was obtained for the diagnosis of AR with sensitivity and specificity of 80% and 79% for GB and 70% and 79% for PF, respectively. The area under the receiver-operator characteristics curve was 0.87 for GB and 0.82 for PF. CONCLUSIONS: GB and PF are diagnostic molecular markers of AR. GB and PF blood levels are also increased in case of viral infections or PTLD. Serial blood testing for GB and PF might be predictive of early intestinal graft dysfunction and should be interpreted in the context of the histological and virological analyses.

The Italian multiorgan donor cancer screening protocol: 2002-2005 experience.

BACKGROUND: We describe the results of the application of the Italian donor cancer screening protocol to all the 7608 candidate multiorgan donors presented in Italy in 2002-2005. METHODS: All suspect findings raised in the two presurgical and surgical phases of the protocol were investigated by extemporary pathologic evaluation. Donors were classified as standard risk (no transmissible risk); nonstandard risk (low-risk of transmission, eligibility restricted to certified clinical emergencies pending informed consent); and unacceptable risk (unconditional exclusion because of high-risk pathologies). RESULTS: The protocol was successfully implemented for all 7608 candidates. In addition to 8 (0.1%) independent exclusions, clinical suspicion of cancer was raised for 337 (4.6%) donors. According to pathological examination 198 donors (2.6%) were judged at unacceptable risk of tumor transmission; 80 (1%) were included in the "standard risk". Used standard risk and nonstandard risk donors provided a total of 241 organs in 231 recipients. Although no suspect was raised after implementation of the protocol, a malignant tumor was discovered after organ transplantation in 14 (0.2%) donors. All the recipients transplanted with organs from ascertained nonstandard risk donors or from neoplastic donors who donated by accident have been carefully followed. At the time of most recent follow-up no donor/recipient tumor transmission has been reported. CONCLUSIONS: Implementation of the multiorgan cancer screening protocol is feasible at a national level in Italy. In view of the increasing demand for organs our protocol provides a useful tool for rationalization of the use of organs from neoplastic marginal donors.

Tissue hepatitis C virus RNA quantification and protein expression help identify early hepatitis C virus recurrence after liver transplantation.

We compared tissue hepatitis C virus (HCV) RNA polymerase chain reaction quantification and HCV immunohistochemistry (IHC) to histology in biopsy tissues in order to differentiate between acute rejection and HCV hepatitis recurrence early after orthotopic liver transplantation (OLT). We analyzed the first biopsy performed because of alteration of serum aminotransferases in 65 consecutive OLT patients with HCV genotype 1b. In the histological analysis, we quantified the portal tracts, Councilman bodies, Councilman body/portal tract (CP) ratio, steatosis, and Knodell and Ishak scores. The 52 patients (80%) with histological HCV recurrence [recurrence-positive (Rec+)] were separated from the 6 (9%) with acute rejection and the 7 (11%) with undetermined pathological features [recurrence-negative (Rec-)]. HCV RNA strongly correlated with HCV IHC, regardless of the histological diagnosis (P < 0.001). Both HCV RNA and HCV IHC were significantly associated with CP ratio (P = 0.041 and P = 0.008). No statistical correlation was found between HCV RNA, HCV IHC, and the other histopathologic features or the hepatitis scores. HCV RNA, HCV IHC, and CP ratio were the only variables able to discriminate between Rec+ and Rec- patients (Mann-Whitney test P < 0.001, P < 0.001, P = 0.014). In conclusion, a combined evaluation of histology, tissue HCV RNA, and HCV IHC significantly discriminated between OLT patients with or without HCV recurrence.

Pulmonary lymphangioleiomyomatosis in a karyotypically normal man without tuberous sclerosis complex.

RATIONALE: The three previously reported cases of conclusively documented pulmonary lymphangioleiomyomatosis (LAM) in men were associated with definite or probable tuberous sclerosis complex (TSC). OBJECTIVES: To describe an unequivocal case of pulmonary LAM occurring in a man with no clinical or genotypic evidence of TSC. METHODS: At high-resolution computed tomography, a 37-year-old phenotypically and karyotypically normal man with left pneumothorax and massive pulmonary collapse had widespread thin-walled cysts throughout both lungs. Histological diagnosis of LAM was performed on biopsy material, and immunohistochemically confirmed with the HMB-45 monoclonal antibody. MEASUREMENTS AND MAIN RESULTS: Remarkably, the HMB-45-positive cells lining the cysts also showed strong reactivity for estrogen and progesterone receptor proteins. TSC was clinically excluded, and TSC1 and TSC2 germline mutations were not detected at DNA analysis. CONCLUSIONS: This article indicates that occurrence of LAM may be possible in a chromosomally normal man unaffected by TSC. On diagnostic grounds, the possibility of LAM should be borne in mind when diffuse cystic lung disease occurs in a man, even in the absence of signs of TSC.

De novo autoimmune hepatitis in liver transplant: State-of-the-art review.

In the two past decades, a number of communications, case-control studies, and retrospective reports have appeared in the literature with concerns about the development of a complex set of clinical, laboratory and histological characteristics of a liver graft dysfunction that is compatible with autoimmune hepatitis. The de novo prefix was added to distinguish this entity from a pre-transplant primary autoimmune hepatitis, but the globally accepted criteria for the diagnosis of autoimmune hepatitis have been adopted in the diagnostic algorithm. Indeed, de novo autoimmune hepatitis is characterized by the typical liver necro-inflammation that is rich in plasma cells, the presence of interface hepatitis and the consequent laboratory findings of elevations in liver enzymes, increases in serum gamma globulin and the appearance of non-organ specific auto-antibodies. Still, the overall features of de novo autoimmune hepatitis appear not to be attributable to a univocal patho-physiological pathway because they can develop in the patients who have undergone liver transplantation due to different etiologies. Specifically, in subjects with hepatitis C virus recurrence, an interferon-containing antiviral treatment has been indicated as a potential inception of immune system derangement. Herein, we attempt to review the currently available knowledge about de novo liver autoimmunity and its clinical management.

Facing the enigma of the vascular network in hepatocellular carcinomas in cirrhotic and non-cirrhotic livers.

AIMS: In this paper we aimed to analyse the typology and the phenotype of the different vascular modifications in human hepatocellular carcinomas (HCCs) with a new immunomorphological and gene expression approach. We also attempted to correlate these modifications with the histological parameters of tumour aggressiveness and the surrounding liver parenchyma. METHODS: Ninety-six HCCs (from 80 patients) were retrospectively enrolled, 46 occurring in non-cirrhotic livers, and 50 in livers transplanted for cirrhosis. Histopathological analysis, immunohistochemistry for CD34, Nestin and WT1 and RT-PCR for Nestin, transforming growth factor-ß1 (TGFß1) and insulin-like growth factor 1 (IGF1R) mRNA were performed in all nodules. RESULTS: By correlating the CD34 and Nestin immunoreactivity in HCC vasculature with the tumorous architecture, we identified four vascular patterns (named from 'a' to 'd'). Each of them was characterised by different expressions of TGFß1 and IGF1R mRNA. Pattern a showed CD34-positive/Nestin-negative sinusoids, and was prevalent in microtrabecular lesions. Pattern b showed similar morphology and architecture as pattern a, but with Nestin-positive sinusoids and a significant 'boost' in IGF1R and TGFß1 mRNAs. In patterns c and d a progressive sinusoid loss and a gain of newly formed arterioles were seen. Notably, HCCs with pattern a arose more frequently in cirrhosis (p=0.024), and showed lower incidence of microvascular invasion (p=0.002) and infiltration (p=0.005) compared with HCCs with other patterns. CONCLUSIONS: Although future studies are surely required, the identification of different vascular profiles in HCCs from cirrhotic and non-cirrhotic livers may help clarify the relationship between HCC progression and aggressiveness.

Predictive value of biological markers for hepatocellular carcinoma patients treated with orthotopic liver transplantation.

PURPOSE: To help stratify candidates with hepatocellular carcinoma (HCC) for orthotopic liver transplantation (OLT), biomarkers are needed that are capable of predicting recurrence of disease (ROD). We investigated the prognostic role in this setting of immunohistochemical markers reported previously to predict poor prognosis in HCC patients treated with resection. EXPERIMENTAL DESIGN: Eighty-three patients with HCC who underwent OLT between 1987 and 2001 with a minimum clinical follow up of 12 months were included in this retrospective study. We analyzed immunohistochemical expression of the adhesion molecules E-cadherin and beta-catenin (membrane/nuclear localization), MIB-1 proliferative index and the cyclin-dependent kinase inhibitor p27, alongside the main clinical-pathological variables. RESULTS: At univariate analysis, vascular thrombosis, high MIB-1 index, lower membrane expression of E-cadherin and beta-catenin, and nuclear beta-catenin localization were associated with ROD. At multivariate analysis, only MIB-1 index, low equal E-cadherin (with respect to non-neoplastic surrounding tissue), and nuclear beta-catenin appeared as independent predictors of ROD. The logistic regression analysis model indicated that detection of any one parameter was associated with at least 88% estimated risk of ROD (up to 99% for all three). CONCLUSIONS: We propose these three molecular parameters as an additional tool for rational selection of OLT candidates among HCC patients (stratification according to the risk of ROD might help provide a similar life expectancy for cirrhotic candidates with and without HCC).

Diffuse calcifications protect carotid plaques regardless of the amount of neoangiogenesis and related histological complications.

BACKGROUND: Neoangiogenesis is crucial in plaque progression and instability. Previous data from our group showed that Nestin-positive intraplaque neovessels correlated with histological complications. The aim of the present work is to evaluate the relationship between neoangiogenesis, plaque morphology, and clinical instability of the plaque. MATERIALS AND METHODS: Seventy-three patients (53 males and 20 females, mean age 71 years) were consecutively enrolled. Clinical data and 14 histological variables, including intraplaque hemorrhage and calcifications, were collected. Immunohistochemistry for CD34 and Nestin was performed. RT-PCR was performed to evaluate Nestin mRNA (including 5 healthy arteries as controls). RESULTS: Diffusely calcified plaques (13/73) were found predominantly in females (P = 0.017), with a significantly lower incidence of symptoms (TIA/stroke (P = 0.019) than noncalcified plaques but with the same incidence of histological complications (P = 0.156)). Accordingly, calcified and noncalcified plaques showed similar mean densities of positivity for CD34 and Nestin. Nestin density, but not CD34, correlated with the occurrence of intraplaque hemorrhage. CONCLUSIONS: Plaques with massive calcifications show the same incidence of histological complications but without influencing symptomatology, especially in female patients, and regardless of the amount of neoangiogenesis. These results can be applied in a future presurgical identification of patients at major risk of developing symptoms.

A histopathologic screening method for rational use of organs from prostate-specific antigen-positive multiorgan donors: the Italian Emilia-Romagna Region experience.

Reduction of waiting-list length requires extension of the organ-donor pool to elderly males bearing an higher risk of prostate cancer incidence. Prostate-cancer screening in organ donors is currently based on prostate-specific antigen (PSA) assays (total PSA and free/total PSA). However, the specificity of these assays is restricted, limiting risk-benefit analysis. Since 2001, 33 multiorgan donor candidates presenting within Emilia-Romagna (Italy) with suspect ultrasonography or abnormal PSA values were submitted to a histopathologic screening method of the entire prostate based on extemporary frozen-section analysis (maximum 1 hour) of over 50% of the organ at 0.1 mm cutting levels. Extemporary diagnosis of adenocarcinoma was made in 12 (36%) cases, corresponding to 4.5% of the male candidates aged more than 50 years in the donor pool. In all cases, the final diagnosis confirmed the extemporary analysis. As well as maximizing safety, this novel approach should permit more refined risk-benefit analysis.

Histopathological evaluation of recurrent hepatitis C after liver transplantation: a review.

Although the morphological features of hepatitis C virus (HCV) recurrence after orthotopic liver transplantation (OLT) have been well established in the last decades, the differential diagnosis still represents a challenge for the pathologist, especially early recurrent hepatitis C vs mild acute cellular rejection. The present review focuses on the role of the pathologist and the pathology laboratory in the management of recipients with recurrent hepatitis C, the usefulness of early and late post-OLT liver biopsies, and the potential role of ancillary techniques (immunohistochemistry and reverse transcription-polymerase chain reaction, RT-PCR). The English literature on the topic is reviewed, focusing on the histopathology, the immunohistochemistry and the use of RT-PCR on HCV-positive post-OLT biopsies. The different histopathological illustrations of early and chronic recurrent hepatitis C are presented, with special focus on the main differential diagnoses and those features with prognostic relevance (cholestasis above all). The usefulness of ancillary techniques are discussed, especially HCV RNA quantitation by RT-PCR. Finally, the usefulness of long-term protocol biopsies is addressed: their usefulness for the study of allograft disease progression is clear, but their meaning in the long term is still debated. The significance of plasma cell infiltrate in HCV-positive allografts, the prognostic weight of graft steatosis, and the impact of donor age in recurrent hepatitis C also represent additional open issues.

Molecular alterations in proteasomes of rat liver during aging result in altered proteolytic activities.

Aging induces alterations of tissue protein homoeostasis. To investigate one of the major systems catalysing intracellular protein degradation we have purified 20S proteasomes from rat liver of young (2 months) and aged (23 months) animals and separated them into three subpopulations containing different types of intermediate proteasomes with standard- and immuno-subunits. The smallest subpopulation ΙΙΙ and the major subpopulation Ι comprised proteasomes containing immuno-subunits ß1i and ß5i beside small amounts of standard-subunits, whereas proteasomes of subpopulation ΙΙ contained only ß5i beside standard-subunits. In favour of a relative increase of the major subpopulation Ι, subpopulation ΙΙ and ΙΙΙ were reduced for about 55 % and 80 %, respectively, in aged rats. Furthermore, in all three 20S proteasome subpopulations from aged animals standard-active site subunits were replaced by immuno-subunits. Overall, this transformation resulted in a relative increase of immuno-subunit-containing proteasomes, paralleled by reduced activity towards short fluorogenic peptide substrates. However, depending on the substrate their hydrolysing activity of long polypeptide substrates was significantly higher or unchanged. Furthermore, our data revealed an altered MHC class I antigen-processing efficiency of 20S proteasomes from liver of aged rats. We therefore suggest that the age-related intramolecular alteration of hepatic proteasomes modifies its cleavage preferences without a general decrease of its activity. Such modifications could have implications on protein homeostasis as well as on MHC class I antigen presentation as part of the immunosenescence process.

Nestin and WT1 expression in atheromathous plaque neovessels: association with vulnerability.

INTRODUCTION: Neoangiogenesis is crucial for the progression and vulnerability of atheromasic lesions. Since adult vasa vasorum, which represent the neoangiogenetic burden of healthy arteries, constitutively express Nestin and Wilms Tumor (WT1), the aims of the present study are: i) to describe and quantify Nestin and WT1 in plaque neovessels; ii) to investigate the relationship between neovessel phenotype and plaque instability. METHODS: We prospectively evaluated 49 consecutive carotid endarterectomy specimens. Histopathological characteristics were separately collected, particularly the intraplaque histological complications. Immunohistochemistry was carried out for CD34, Nestin and WT1; the density of positivity was evaluated for each marker. RT-PCR was performed to assess Nestin and WT1 mRNA levels on the first 10 plaques and on 10 control arteries. RESULTS: Six (12.2%) plaques showed no neoangiogenesis. In the others, the mean immunohistochemical densities of CD34, Nestin, and WT1-positive structures were 41.88, 28.84 and 17.68/mm2. Among the CD34+ neovessels, 68% and 42% expressed Nestin and WT1 respectively, i.e., nearly 36% of the neovessels resulted to be Nestin+/WT1-. Furthermore, complicated plaques (n=30) showed significantly more CD34 and Nestin-positive vessels than uncomplicated plaques (n=13; P=0.045 and P=0.009), while WT1 was not increased (P=0.139). RT-PCR confirmed that WT1 gene expression was 3-fold lower than Nestin gene in plaques (p=0.001). CONCLUSIONS: Plaque neoangiogenesis shows both a Nestin+/WT1- and a Nestin+/WT1+ phenotype. The Nestin+/WT1- neovessels are significantly more abundant in complicated (vulnerable) plaques. The identification of new transcription factors in plaque neoangiogenesis, and their possible regulation, can open new perspectives in the therapy of vulnerable plaques.