Functional Immune Anatomy of the Liver-As an Allograft.

The liver is an immunoregulatory organ in which a tolerogenic microenvironment mitigates the relative "strength" of local immune responses. Paradoxically, necro-inflammatory diseases create the need for most liver transplants. Treatment of hepatitis B virus, hepatitis C virus, and acute T cell-mediated rejection have redirected focus on long-term allograft structural integrity. Understanding of insults should enable decades of morbidity-free survival after liver replacement because of these tolerogenic properties. Studies of long-term survivors show low-grade chronic inflammatory, fibrotic, and microvascular lesions, likely related to some combination of environment insults (i.e. abnormal physiology), donor-specific antibodies, and T cell-mediated immunity. The resultant conundrum is familiar in transplantation: adequate immunosuppression produces chronic toxicities, while lightened immunosuppression leads to sensitization, immunological injury, and structural deterioration. The "balance" is more favorable for liver than other solid organ allografts. This occurs because of unique hepatic immune physiology and provides unintended benefits for allografts by modulating various afferent and efferent limbs of allogenic immune responses. This review is intended to provide a better understanding of liver immune microanatomy and physiology and thereby (a) the potential structural consequences of low-level, including allo-antibody-mediated injury; and (b) how liver allografts modulate immune reactions. Special attention is given to the microvasculature and hepatic mononuclear phagocytic system.

Banff fibrosis study: multicenter visual assessment and computerized analysis of interstitial fibrosis in kidney biopsies.

Increasing interstitial fibrosis (IF) in native and kidney transplant biopsies is associated with functional decline and serves as a clinical trial end point. A Banff 2009 Conference survey revealed a range in IF assessment practices. Observers from multiple centers were asked to assess 30 renal biopsies with a range of IF and quantitate IF using two approaches on trichrome, Periodic acid-Schiff (PAS) and computer-assisted quantification of collagen III immunohistochemistry (C-IHC) slides, as well as assessing percent of cortical tubular atrophy% (TA%) and Banff total cortical inflammation score (ti-score). C-IHC using whole slide scans was performed. C-IHC assessment showed a higher correlation with organ function (r = -0.48) than did visual assessments (r = -0.32--0.42); computerized and visual C-IHC assessment also correlated (r = 0.64-0.66). Visual assessment of trichrome and C-IHC showed better correlations with organ function and C-IHC, than PAS, TA% and ti-score. However, visual assessment of IF, independent of approach, was variable among observers, and differences in correlations with organ function were not statistically significant among C-IHC image analysis and visual assessment methods. C-IHC image analysis correlated among three centers (r > 0.90, p < 0.0001, between all centers). Given the difficulty of visual IF assessment standardization, C-IHC image could potentially accomplish standardized IF assessment in multicenter settings.

C4d immunopositivity is uncommon in ABO-compatible liver allografts, but correlates partially with lymphocytotoxic antibody status.

AIMS: To determine whether C4d immunopositivity helps recognition of humoral rejection in dysfunctional liver allografts. METHODS AND RESULTS: C4d immunopositivity was retrospectively evaluated in liver allografts. There were three staining patterns: portal venular plexus, sinusoidal and hepatocellular. The latter was related to ischaemic necrosis and not scored as positive. C4d immunopositivity was not encountered in 10 preperfusion or 15 consecutive early protocol biopsies. However, three of 12 early protocol biopsy specimens from crossmatch-positive patients were C4d+, two showing repeated positivity on at least one further biopsy specimen, while others remained negative. C4d was also positive in 2/16 early moderate acute cellular rejections, 3/14 cases of centrilobular necroinflammation, 3/11 biliary obstructions, 3/13 chronic rejections and 1/10 primary non-functional allografts. CONCLUSION: C4d immunopositivity is uncommon in liver allografts. There is a weak positive correlation with a positive lymphocytotoxic crossmatch and some patterns of allograft dysfunction. The morphological associations resemble those reported in lymphocytotoxic crossmatch-positive patients, plus occasional sinusoidal and hepatocellular injury. Although the practical utility of C4d immunohistochemistry seems limited, it may identify a small subgroup of individuals in whom chronic humoral microvascular injury contributes to allograft dysfunction.

Transplant histopathology for the general histopathologist.

The number of patients undergoing solid organ transplants and surviving long-term has increased enormously in the last 10 years. This means that pathologists in non-specialist transplant centres are increasingly involved in the interpretation of biopsy and autopsy material from allograft recipients. This includes evaluation of allograft histology, or specimens from other native tissues, which nonetheless still have to be assessed in the setting of transplantation and immunosuppressive therapy. In this first review article we will provide an overview of the pathology of lung transplantation, and briefly describe heart and pancreatic transplants, as well as aspects of general surgical pathology and the role of the autopsy in these patients.

Liver transplantation for alcoholic cirrhosis: long term follow-up and impact of disease recurrence.

BACKGROUND: Alcoholic liver disease has emerged as a leading indication for hepatic transplantation, although it is a controversial use of resources. We aimed to examine all aspects of liver transplantation associated with alcohol abuse. METHODS: Retrospective cohort analysis of 123 alcoholic patients with a median of 7 years follow-up at one center. RESULTS: In addition to alcohol, 43 (35%) patients had another possible factor contributing to cirrhosis. Actuarial patient and graft survival rates were, respectively, 84% and 81% (1 year); 72% and 66% (5 years); and 63% and 59% (7 years). After transplantation, 18 patients (15%) manifested 21 noncutaneous de novo malignancies, which is significantly more than controls (P=0.0001); upper aerodigestive squamous carcinomas were overrepresented (P=0.03). Thirteen patients had definitely relapsed and three others were suspected to have relapsed. Relapse was predicted by daily ethanol consumption (P=0.0314), but not by duration of pretransplant sobriety or explant histology. No patient had alcoholic hepatitis after transplantation and neither late onset acute nor chronic rejection was significantly increased. Multiple regression analyses for predictors of graft failure identified major biliary/vascular complications (P=0.01), chronic bile duct injury on biopsy (P=0.002), and pericellular fibrosis on biopsy (P=0.05); graft viral hepatitis was marginally significant (P=0.07) on univariate analysis. CONCLUSIONS: Alcoholic liver disease is an excellent indication for liver transplantation in those without coexistent conditions. Recurrent alcoholic liver disease alone is not an important cause of graft pathology or failure. Potential recipients should be heavily screened before transplantation for coexistent conditions (e.g., hepatitis C, metabolic diseases) and other target-organ damage, especially aerodigestive malignancy, which are greater causes of morbidity and mortality than is recurrent alcohol liver disease.

Dual Y-chromosome painting and immunofluorescence staining of archival human liver transplant biopsies.

Combining fluorescence in situ hybridization (FISH) and indirect immunofluorescence staining of protein markers provides a highly specific method for identifying chromosomes in phenotypically defined cells and tissues. We developed a technique enabling dual chromosome painting and immunofluorescence staining of archival formalin-fixed, paraffin-embedded material, and used this to phenotype chimeric cells in female-to-male human liver transplants.

Letrozole as primary medical therapy for locally advanced and large operable breast cancer.

AIMS: To investigate the efficacy of letrozole 2.5 mg and 10 mg used as primary neoadjuvant therapy for patients with locally advanced and large operable breast cancer. PATIENTS AND METHODS: Twenty-four postmenopausal patients with locally advanced or large operable breast cancer were treated in two consecutive series with letrozole 2.5 mg (n = 12) or letrozole 10 mg (n = 12). Response at three months was measured by change in tumor volume according to WHO criteria (partial response was defined as a reduction in tumor volume > or = 65%). Tumor volumes were assessed clinically, by ultrasound and mammography, and pathologically. RESULTS: All 24 patients were estrogen receptor-positive, were considered 'receptor-rich', and mean age was 77.6 years and 71.6 years in the letrozole 2.5 mg and 10 mg treatment groups, respectively. There were five complete clinical responses and seven partial clinical responses in the patients treated with 2.5 mg letrozole, and nine partial responses and three patients with stable disease in patients treated with 10 mg letrozole. Assessed by ultrasound and mammography, the 12 patients treated with 2.5 mg had one complete response, nine partial responses and two with no change. In the 12 patients treated with 10 mg letrozole, imaging gave eight partial responses and four with no change. One patient treated with the 2.5 mg dose had a complete clinical and pathological response. There was no significant difference between the two doses in effect on tumor volume, and no recordable side effects associated with either dose. CONCLUSION: Letrozole used in a neoadjuvant setting is highly effective, producing clinically beneficial reductions in tumor volume allowing all patients to have breast conserving surgery, and has an acceptable safety profile.

Arteriolitis in renal transplant biopsies is associated with poor graft outcome.

AIMS: The Banff 1997 classification of renal allograft pathology identifies arteriolitis as a finding of uncertain significance. We sought to improve our understanding of arteriolitis by correlating its occurrence with histopathological and clinical parameters. METHODS AND RESULTS: Twenty allograft kidney biopsies from 19 patients, showing arteriolitis, were identified. Arterioles were defined as small vessels with: (1) wall thickness of 1-3 myocytes; (2) diameter less than one-third of an adjacent glomerulus; and (3) discontinuous or absent elastica. Arteriolitis was defined as mural infiltration by lymphocytes. Other histological findings were categorized according to the Banff 1997 working formulation. Ten biopsies (50%) showed type IIA rejection, seven (35%) showed type I rejection, and three (15%) showed borderline change. Two patients with borderline change had acute rejection in the next biopsy. None of the seven patients with type I rejection had previous or subsequent type II rejection on biopsy. A total 11/20 biopsies (10/19 patients) showing arteriolitis had type IIA rejection in the index or next biopsy. On follow-up, graft loss due to rejection occurred in 5/19 (26%) patients (median 126 days); all had shown type IIA rejection on a previous biopsy. Chronic allograft nephropathy developed in a further 4/19 (21%) patients (median 157 days), of whom three had shown only type I rejection on biopsy. CONCLUSION: Arteriolitis is associated with acute rejection, often type II rejection, and is associated with poor graft outcome. Other causes of arteriolitis were not encountered in this series.

Apoptosis and carcinogenesis.

Apoptosis has long been known to be effected through a common sequence of structural changes, despite the wide variety of initiating stimuli. These common structural events appear to depend upon activation of a set of enzymes (caspases) which direct a strongly conserved, terminal effector pathway. The regulation of this pathway, and in particular its coupling to DNA damage, appears to be critical in maintaining at low levels the number of mutated cells within tissues. The frequency with which tumours (experimental and human) bear deficiency in p53 or MSH-2 repair function may indicate the importance of these proteins in coupling DNA damage to apoptosis.

p53-independent DNA repair and cell cycle arrest in embryonic stem cells.

The role of p53 in DNA repair and cell cycle checkpoint after ultraviolet irradiation was investigated in an embryonic stem cell line homozygous for a targeted deletion of p53. Results indicate that loss of p53 does not alter the capacity of ES cells to respond to DNA damage. Wild-type and p53-deficient cells showed similar cessation of DNA synthesis after UV damage and similar ultimate capacity to repair a transiently transfected reporter plasmid. Interestingly, in the absence of DNA damaging treatment, the transit of p53-deficient cells through S phase was slower than wild-type cells. We suggest that this may result from the absence of a p53-dependent response to endogenous DNA damage: without p53 sensing endogenous damage leading to immediate repair, such damage may persist and thus delay DNA synthesis.

Altered DNA repair and dysregulation of p53 in IRF-1 null hepatocytes.

The tumor suppressor proteins IRF-1 and p53 are involved in response pathways after DNA damage. In different cell types, IRF-1 and p53 can cooperate to produce cell cycle arrest (embryo fibroblasts) or can independently trigger apoptosis (lymphoid cells). p53 may also regulate DNA repair, but there is no information on IRF-1 and repair. The cell lineage dependency of these effects precludes extrapolation of findings to other tissues of relevance to human cancer. Here, we report the consequences of IRF-1 deficiency for apoptosis, cell cycle arrest, and DNA repair in primary hepatocytes after DNA damage and extend previous work on the role of p53 in hepatocytes. IRF-1-deficient hepatocytes showed reduced DNA repair activity compared with wild-type, as assessed by unscheduled DNA synthesis after UV irradiation (10J/m2) and by host reactivation of a UV-damaged reporter construct. p53-deficient hepatocytes also showed reduced unscheduled DNA synthesis after UV, but there was no impairment of specific repair in host reactivation assays. IRF-1 deficiency did not affect the p53-dependent G1/S arrest after UV irradiation. Hepatocyte apoptosis after UV treatment, previously reported to be independent of p53, was also independent of IRF-1. However, IRF-1 deficiency produced dysregulation of p53, manifested as increased transactivation of a p53-reporter plasmid in undamaged hepatocytes, and accelerated p53 stabilization after DNA damage. Hence, in hepatocytes, IRF-1 is not required for growth arrest or apoptosis after DNA damage, but the results suggest for the first time a role in DNA repair regulation.

UV but not gamma-irradiation induces specific transcriptional activity of p53 in primary hepatocytes.

The mechanisms are poorly understood by which p53 can stimulate different downstream events, including growth arrest, DNA repair, and apoptosis, after DNA damage. Changes in protein levels do not predict a particular p53 response, but it is possible that differences in functional activities such as transactivation are important. The present report describes the successful use of a specific p53 reporter plasmid transfected into primary murine hepatocytes to evaluate p53 transactivation activity over time after two different genotoxic injuries (gamma-irradiation, 15 Gy and UV-c irradiation, 10 J/m2) known to produce p53-dependent growth arrest in this cell type. The results show that UV injury to hepatocytes was followed by a transient increase in transcriptional activation of the reporter plasmid by p53 and that this response preceded changes in p53 protein levels, as assessed by immunocytochemistry. By contrast, gamma-irradiation injury failed to induce detectable changes in either transactivation activity or hepatocyte p53 protein levels. The data show that p53 responses to DNA damage are dependent on both cell and injury type and suggest that in hepatocytes they can be independent of protein concentration and specific transcriptional activity. The results have implications for how particular dysfunctional p53 mutations in carcinogenesis could alter hepatocyte responses to different DNA injuries.

p53 Deficiency in liver reduces local control of survival and proliferation, but does not affect apoptosis after DNA damage.

Despite good evidence for p53 dysfunction in human hepatocellular carcinomas, little is known of the significance of p53 to normal hepatocytes and whether p53 dysfunction is relevant to early hepatocarcinogenesis. We have therefore examined the consequences of targeted p53 deficiency in hepatocytes for regulation of apoptosis, proliferation, and ploidy. p53 deficiency was silent in normal liver and did not affect progression from diploidy to polyploidy in the aging liver. However, in primary culture the absence of p53 resulted in increased hepatocyte proliferation indices and decreased sensitivity to proliferation inhibition by TGFbeta. Moreover, p53-deficient cells continued to survive and proliferate under conditions of minimal trophic support that led to growth arrest and apoptosis of wild-type cells. In vivo, p53-deficient mice had enhanced proliferative responses to both xenobiotic hepatomitogen and CCl4-induced liver necrosis, although lack of persistent proliferation showed that other control mechanisms are important. There was no simple relationship between p53 and apoptosis after DNA damage because UV irradiation led to p53-independent apoptosis, even though p53 was stabilized. However, p53 did couple DNA damage to growth arrest, and abnormal mitoses after gamma-irradiation of regenerating p53 null livers demonstrated circumstances where loss of G1 and G2 checkpoints may generate abnormal ploidy. Thus p53 becomes important when hepatocytes are released from G0 and stressed, sensitizing them to mitogen and cytokine regulators of cell cycle progression and apoptosis. Hence p53 deficiency is likely to be significant in an environment of persistent regenerative stimuli and unfavorable trophic support or in the presence of other enabling genetic lesions. This model is relevant to human hepatocarcinogenesis, which almost always occurs against a background of chronic hepatocellular destruction in hepatitis and cirrhosis. In that context, by reducing the need for cytokine support and disabling DNA damage-induced growth arrest, p53 deficiency should facilitate the expansion of preneoplastic clones in chronic liver disease.

p53 and apoptosis.

Loss of function of the p53 tumour suppressor gene is a frequent and important event in the genesis or progression of many human malignancies. Loss of p53 dependent apoptosis is believed to be critical to carcinogenesis in many of these cases, suggesting the possibility to therapeutically restore this pathway and directly eliminate malignant cells or increase or restore their sensitivity to chemotherapeutic agents. The regulation of p53-dependent responses is complex and variable between cell types, and whether a cell undergoes apoptosis after activation of p53 is highly sensitive to signal context, including environmental and cell intrinsic influences. This article focuses upon p53-dependent apoptosis, considering current understanding of the biochemical steps involved, the factors determining selection of apoptosis over other p53-dependent responses, the significance of p53-dependent apoptosis for the genesis, progression and drug resistance of human cancers, and finally the prospects for clinical manipulation of this pathway in cancer therapy.

Cell death in health and disease: the biology and regulation of apoptosis.

Apoptosis is a morphologically stereotyped form of cell death, prevalent in multicellular organisms, by which single cells are deleted from the midst of living tissues. Recognition of the cellular corpses and their removal by phagocytosis occurs without disturbance to tissue architecture or function and without initiating inflammation. Apoptosis is regulable and is of fundamental importance to tissue development and homeostasis. Cellular susceptibility to apoptosis is determined by a variety of signals, of both extracellular and internal origin, including proliferative status. Dysregulated apoptosis is important in the pathogenesis of several important human diseases including neoplasia, and recognition of the defects involved is prompting development of new therapeutic strategies.

Primary splenic large cell anaplastic lymphoma associated with HIV infection.

We report a case of primary splenic B-cell CD30 positive large cell anaplastic lymphoma developing in an HIV positive patient. The tumour cells expressed Epstein-Barr virus-associated antigens.

Evaluation of glutathione S-transferase Pi in non-invasive ductal carcinoma of breast.

Glutathione S-transferase Pi (GST P) has been reported to be a marker of dysplastic lesions. For this reason expression of GST P by intraduct breast carcinoma was evaluated by immunohistochemistry. Thirty-seven of 92 carcinomas (40%) were GST P positive. GST P staining did not correlate with histological variables, c-erbB-2 overexpression or with clinical outcome. The GST P status of recurrences did not correlate with that of the index lesion. There is little evidence that GST P is a useful marker of the potential of intraduct breast carcinoma to become invasive.