Fulminant hepatic failure is defined by the sudden onset of severe liver injury accompanied by hepatic encephalopathy in an individual who previously had no evidence of liver disease. This disease causes multiple organ failure and is associated with a high mortality. The most frequently recognised cause of fulminant or subfulminant hepatic failure is viral hepatitis. Data are now emerging to support the hypothesis that, irrespective of the aetiology of fulminant hepatic failure, the host's immune response (including production of proinflammatory cytokines and mediators) contributes to microcirculatory disturbances that result in hypoxic injury and cell death (apoptosis). Impairment of the scavenger function of the reticuloendothelial cell system further contributes to reduced hepatic blood flow and ischaemic necrosis. An increased understanding of the molecular pathogenesis of fulminant hepatic failure now enables new molecular therapeutic modalities to be tested. Given the complexity of this multi-dimensional disorder, the challenge is to provide a rational basis for treatment. This might include enhancement or suppression of immune responsiveness by manipulation of endogenous cytokine synthesis or by cytokine administration and, at the same time, use of strategies to increase hepatic regeneration.

Wilms' tumour (WT; nephroblastoma), a kidney neoplasm, is one of the most frequently occurring solid tumours of childhood. It arises from the developing kidney by genetic and epigenetic changes that lead to the abnormal proliferation of renal stem cells (metanephric blastema). WT serves as a paradigm for understanding the relationship between loss of developmental control and gain of tumourigenic potential. In particular, loss of function of tumour suppressor genes has been implicated in the development of WT, and the Wilms' tumour suppressor gene WT1 (at chromosome 11p13) was the second tumour suppressor gene to be cloned, after the retinoblastoma gene RB-1. WT1 plays an essential role in kidney development, but is mutated in only approximately 20% of WTs, which suggests that further lesions and genetic loci are involved in Wilms' tumourigenesis. Other chromosomal regions associated with WT include 7p, 11p15, 16q and 17q. Although many of these loci probably contain tumour suppressor genes, imprinted genes (genes showing expression of only one parental allele) and oncogenes have also been implicated in WT. Some loci have been shown to be associated with particular clinical outcomes, suggesting that they might be used to determine prognosis, and especially to identify poor prognostic subgroups that can be targeted for aggressive and/or novel therapies.

Atherosclerosis is a pathological process that takes place in the major arteries and is the underlying cause of heart attacks, stroke and peripheral artery disease. The earliest detectable lesions, called fatty streaks, contain macrophage foam cells that are derived from recruited monocytes. More-advanced atherosclerotic lesions, called fibro-fatty plaques, are the result of continued monocyte recruitment and smooth muscle cell migration and proliferation. Variable numbers of CD4+ T cells are found in atherosclerotic lesions, and cytokines secreted by T helper 1 (Th1)- or Th2-type cells can have a profound influence on macrophage gene expression within atherosclerotic plaques. This review briefly addresses the key features of macrophage biology and discusses the factors that influence the growth and development of atherosclerotic lesions (atherogenesis). It then considers the potential role of chemokines in mediating monocyte recruitment and macrophage differentiation within atherosclerotic lesions.

Vitiligo is a depigmenting disorder characterised by the loss of melanocytes from the cutaneous epidermis. Although the exact aetiology of vitiligo has not yet been established, the abnormal immune responses frequently observed in vitiligo patients have led to the suggestion that, in some cases, the condition has an autoimmune component. Briefly, circulating autoantibodies and autoreactive T cells that recognise pigment cell antigens have been detected in the sera of a significant proportion of vitiligo patients compared with healthy individuals. In addition, vitiligo is often associated with other disorders that have an autoimmune origin, including Hashimoto's thyroiditis, Graves' disease, type 1 insulin-dependent diabetes mellitus and Addison's disease. Furthermore, effective use of immunosuppressive therapies to treat vitiligo, the association of vitiligo with certain major histocompatibility complex antigens, and evidence from animal models of the disease have all added credence to the hypothesis that immune reactions play a role in vitiligo pathogenesis. This review presents and discusses the evidence for immunological pathomechanisms in vitiligo.

Laminins are a multigene family of extracellular matrix molecules. Quantitatively, they are one of the most abundant glycoproteins present in basement membranes. Functionally, they can modulate several key biological activities, including cell adhesion and migration, gene expression and cell survival. Variability in the spatial and temporal expression of laminins, as well as of their specific receptors of the integrin family, in various tissues and organs, suggests that different laminins perform distinct functions. This article focuses on the human intestinal epithelium as a paradigm to illustrate the potential relationship between laminin–cell interactions and the cell state. This rapidly renewing epithelium consists of spatially separated proliferative and differentiated cell populations located in the crypts and on the villi, respectively. Differential distributions of the various laminins and laminin-binding integrins have been observed along the crypt–villus axis in both the developing and the adult intestine, and important alterations in the pattern of laminin expression have been reported in various intestinal pathologies, such as tufting enteropathy, Crohn's disease and ulcerative colitis, and colorectal cancer. More-direct approaches, including experimentation with in vitro and in vivo models, have provided evidence in support of a role for laminins in intestinal cell functions. Although further work is still needed, laminins emerge more and more as key regulators of specific cell functions important in both intestinal health and intestinal disease.

The Epstein–Barr virus (EBV) is a human herpesvirus that is usually carried lifelong as an asymptomatic infection. EBV is the causative agent of infectious mononucleosis and has been linked to the development of several malignant tumours, including B-cell neoplasms such as Burkitt's lymphoma and Hodgkin's disease, certain forms of T-cell lymphoma, and some epithelial tumours, such as undifferentiated nasopharyngeal carcinoma and a proportion of gastric cancers. All these tumours are characterised by the presence of multiple extrachromosomal copies of the circular viral genome in the tumour cells and the expression of EBV-encoded latent genes, which appear to contribute to the malignant phenotype. An increasing understanding of the function of EBV latent genes and of the nature of the immune response to the virus is providing exciting new possibilities for the treatment of EBV-associated malignancies. For example, adoptive transfer of virus-specific cytotoxic T lymphocytes has already been of value in the treatment of EBV-positive B-cell lymphomas arising in post-transplant patients, and this approach is currently being investigated in other EBV-associated tumours. In addition, gene therapy offers the opportunity to deliver agents that might directly interfere with the function of specific EBV genes. This review summarises the role of EBV in malignancy. In particular, it focuses on the latent proteins as a basis for understanding how EBV might contribute to the process of transformation. Strategies to target EBV in tumours, potentially providing alternative therapeutic approaches, are also discussed.

The transmissible spongiform encephalopathies (TSEs) are a group of fatal neurodegenerative diseases that are also transmissible. The PrP protein is central to the disease process and has been hypothesised to be the infectious agent. Polymorphisms in the PrP gene have been linked to the incubation time of TSE disease, and mutations in the human PrP gene have been suggested to result in genetic TSE disease. Several PrP transgenic models have been developed. These models express PrP from different species, with and without PrP mutations, and at different levels of gene expression. This article discusses the contribution of these transgenic models to our present understanding of the TSE diseases.

The trafficking and processing steps that occur in cells that are infected with influenza virus play a crucial role in the outcome of infection. These steps are targets for new and future anti-viral drugs, and can affect the relative virulence of the virus and its ability to cause disease. The virus first binds to its host cell via specific sialic acid residues, which can control the species tropism of the virus. The internalisation of the virus, into the nucleus of the cell, is dependent on a low pH, and this process is therapeutically targeted by the drug amantadine. Following replication, the newly formed viral genomes leave the nucleus and assemble into infectious particles at the plasma membrane. The targeting and processing of the various viral components at this late stage of the infectious cycle can have a major effect on the ability of the virus to spread and cause disease in its host. Finally, the release of viruses is dependent on the enzyme neuraminidase (NA), and this function has recently been targeted by the NA inhibitors, a new generation of drugs against influenza virus.

T-cell activation is of central importance to the generation of an immune response and is also required as part of the host's ability to recognise self proteins. T cells are activated to differing extents by different ligands. Agonist ligands cause the full range of T-cell activation phenotypes – from activation of signalling cascades, to cytokine secretion or target cell killing, to T-cell proliferation. Partial agonists, which can differ from the agonist by as little as a single amino acid residue, can induce some of these responses but not all. Antagonist ligands can disable the signalling of an agonist ligand. These different types of interaction between ligand and T-cell receptor (TCR) also determine the developmental fate of maturing T cells. Much recent work has focused on how the T cell distinguishes between ligands. At least part of the answer lies in the kinetics of its binding to ligand.

Recent advances in surgical techniques have made it possible to study the changes that are known as degeneration of the intervertebral disc (IVD) in greater depth than ever before. This is an important area of study because degeneration of the lumbar IVDs is associated, perhaps causally, with low back pain: one of the most common and debilitating conditions in the western world. The term degeneration implies an inevitable progression that is characteristic of wear-and-tear-associated conditions. However, modern research on human tissue has shown that this is not the case. Here, disruption of the micro-anatomy that is described as degeneration is an active process, which is probably regulated by locally produced cytokines. This one observation opens up the possibility of inhibiting or even reversing the processes of degeneration. The immediate question is how can the slowly progressive changes of degeneration be treated, particularly as connective tissue repair is thought to be a slow and highly regulated process. In this review, the possibility of using gene therapy as a single-shot, long-lasting therapeutic strategy is discussed, together with an outline of developments in this area to date.

For many years, heat shock or stress proteins have been regarded as intracellular molecules that have a range of housekeeping and cytoprotective functions, only being released into the extracellular environment in pathological situations such as necrotic cell death. However, evidence is now accumulating to indicate that, under certain circumstances, these proteins can be released from cells in the absence of cellular necrosis, and that extracellular heat shock proteins have a range of immunoregulatory activities. The capacity of heat shock proteins to induce pro-inflammatory responses, together with the phylogenetic similarity between prokaryotic and eukaryotic heat shock proteins, has led to the proposition that these proteins provide a link between infection and autoimmune disease. Indeed, both elevated levels of antibodies to heat shock proteins and an enhanced immune reactivity to heat shock proteins have been noted in a variety of pathogenic disease states. However, further evaluation of heat shock protein reactivity in autoimmune disease and after transplantation has shown that, rather than promoting disease, reactivity to self-heat shock proteins can downregulate the disease process. It might be that self-reactivity to heat shock proteins is a physiological response that regulates the development and progression of pro-inflammatory immunity to these ubiquitously expressed molecules. The evolving evidence that heat shock proteins are present in the extracellular environment, that reactivity to heat shock proteins does not necessarily reflect adverse, pro-inflammatory responses and that the promotion of reactivity to self-heat shock proteins can downregulate pathogenic processes all suggest a potential role for heat shock proteins as therapeutic agents, rather than as therapeutic targets.

Group B streptococci (GBS) are an important cause of neonatal sepsis and meningitis, and maternal infection. Although the pathogenesis of GBS infection is not well understood, several virulence factors have been identified. Two prevention strategies have been proposed: chemoprophylaxis and immunoprophylaxis. Implementation of selective intrapartum chemoprophylaxis on the basis of either screening or risk assessment has led to a substantial decrease in the morbidity and mortality of GBS disease in both mothers and infants. Penicillin remains the antibiotic of choice with no reported resistant GBS so far, whereas resistance of 10–20% of GBS to erythromycin and clindamycin has been reported in North America. Chemoprophylaxis based on screening requires optimal detection methods for GBS, which involve selective broth culture of combined vaginal and anal samples. Other conventional methods are useful for rapid identification of heavily colonised women, but are unreliable for the detection of light GBS colonisation because of poor sensitivity. GBS-specific polymerase chain reaction (PCR) assays using real-time PCR coupled with fluorescence-labelling technology offer powerful tools for sensitive and specific, yet rapid (less than 1 h), detection of GBS directly from clinical specimens at the time of delivery. The application of these assays to the current prevention strategies will simplify the prevention practice and rationalise the use of antibiotics. Immunoprophylaxis relies on the development of new vaccines against GBS, and active research is being conducted in this area.

Corneal allotransplantation is the most common and successful form of solid organ transplantation in humans. In uncomplicated cases, the two-year graft survival rate is over 90%. This extraordinary success can be attributed in part to various features of the normal cornea and anterior segment that together account for their ‘immune-privileged’ status. However, despite this success, a significant number of corneal grafts fail and immunological rejection remains by far the leading cause of graft failure. Studies on animal models of corneal transplantation have yielded a wealth of information on the molecular and cellular features of graft rejection, and have established that this process is mediated primarily by CD4+ T cells of the T helper 1 (Th1) phenotype. In addition, studies have elucidated that certain facets of allosensitisation differ between corneal and other solid organ transplants. On the basis of these findings, novel experimental strategies selectively targeting the afferent or efferent arms of corneal alloimmunity have provided promising results in preventing corneal allograft rejection in the laboratory. Finally, because of the global shortage of human donor corneas, there is currently renewed interest in the possibility of using corneas from other species for transplantation into human eyes (xenotransplantation). Preliminary studies on animal models of corneal xenotransplantation have documented both antibody-mediated and cell-mediated responses that might play important roles in the accelerated rejection observed in corneal xenotransplants. This review synthesises the principal concepts emerging from studies of the molecular mechanisms in corneal transplant immunology.

Fas ligand (FasL) induces programmed cell death, or ‘apoptosis’, in cells expressing its cognate receptor, Fas (CD95/APO-1). There is evidence that FasL precludes inflammatory reactions from sites of ‘immune privilege’ by triggering Fas-mediated apoptosis of infiltrating pro-inflammatory cells. The ability of FasL to impair immune responses is being pursued as a possible means of protecting tissue transplants from immunological rejection, and therapeutic promise has been reported in some experiments. However, FasL is becoming an enigmatic molecule, exhibiting pro-inflammatory activity independently of its ability to mediate immune downregulation. FasL can recruit and activate neutrophils and macrophages in some experimental situations. Triggering of Fas in some cell types has been shown to upregulate expression of certain pro-inflammatory cytokines and chemokines, providing an unexpected link between apoptosis and inflammation. FasL appears to contribute to the destruction of Fas-sensitive end-organ cells during inflammation. This appears to occur in two ways: (1) direct killing by cytotoxic immune effector cells expressing FasL; or (2) autocrine cell suicide of end-organ cells that upregulate their own FasL in the inflammatory context. Depending on the condition, or the site of inflammation, either or both mechanisms may occur. Prevention of Fas-mediated end-organ apoptosis and enhancement of Fas-mediated apoptosis of inflammatory cells are emerging as potential anti-inflammatory therapeutic goals.

von Hippel–Lindau (VHL) disease is a dominantly inherited cancer syndrome characterised by predisposition to multiple tumours of the eyes and central nervous system (haemangioblastomas), kidneys (renal cell carcinoma; RCC), adrenal chromaffin cells (phaeochromocytoma), and other organs. The VHL gene was isolated in 1993 and mutations or deletions in the VHL gene have been identified in the germline of nearly all tested individuals with VHL disease. Genotype–phenotype correlations have been observed: individuals with missense mutations are more likely to develop phaeochromocytoma than those with deletions or protein-truncating mutations are, and specific missense mutations at certain codons might not predispose to RCC. In accordance with its role as a tumour suppressor gene, the normal allele of the VHL gene is deleted, mutated or silenced by promoter methylation in the tumours from VHL patients, and in a large proportion of sporadic tumours of the same histological types as observed in VHL disease. Thus, the VHL gene is of major importance in the development of RCC in the general population. Recent advances in understanding the structure and function of the VHL protein (pVHL) have revealed insights into the different phenotypes, with indications that some retention of function might be required for predisposition to phaeochromocytoma. pVHL interacts with many cellular proteins, mainly via one of two protein-binding domains (α and β). The best-characterised interaction is that of pVHL with elongin C, which forms a complex with elongin B and Cullin 2 proteins. This complex has E3 ubiquitin ligase activity and promotes ubiquitin-mediated proteasomal degradation of the hypoxia-inducible factor 1α (HIF-1α) transcription factor under normal oxygen (normoxic) conditions. Loss of pVHL function leads to stabilisation of HIF-1 and expression under normoxic conditions of hypoxia-inducible genes including vascular endothelial growth factor (VEGF), which might explain the hypervascular phenotype of VHL tumours. Several other genes implicated in intra- and intercellular signalling and control of tumour growth are overexpressed in the absence of pVHL, but it is not yet clear which features of pVHL function are most significant for tumour suppression in different tissues. Further advances in understanding pVHL function might eventually enable development of specific therapies for prevention or treatment of VHL tumours and RCC.

Cystic fibrosis (CF) is a common and fatal recessive disease, which is caused by dysfunction of a chloride ion channel, termed the CF transmembrane conductance regulator (CFTR). The CF gene was cloned in 1989; subsequently, several mouse models have been created using gene targeting within embryonic stem cells. This report describes how such animal models provide the opportunity to elucidate disease pathogenesis, correlate genotype with phenotype and develop novel therapies. The current models encompass mice with a complete knockout of CFTR function, with residual CFTR function, and with precise mutations corresponding to those in humans that precipitate CF. All the CF mice demonstrate the characteristic CF ion-transport defect and show some evidence of intestinal disease, but they have a variable level of survival. Genetic background has also been shown to affect the intestinal phenotype of CF mice and this has allowed identification of a genetic modifier locus of CF in humans. Lung disease in human CF is the major cause of death in early adulthood. This is not entirely reproduced in CF mice, but repeat exposure of the lung to clinical pathogens does reveal a significantly abnormal pathogen-related response in the residual-function mice. CF mice have been successfully used to investigate the safety and efficacy of various pharmacological and gene-therapy protocols. As new cloning techniques become available, the models can be refined to ensure that in vivo models continue to be an essential tool for studying CF.

The norepinephrine transporter (NET) has a major role in terminating the neurochemical signal established by the neurotransmitter norepinephrine (NE) in the synaptic cleft. The NET is also the initial site of action for therapeutic antidepressants, and drugs such as cocaine and amphetamines. Polymorphisms in the NET gene have been identified, and associations with several disorders such as depression have been proposed but not established. However, evidence of a direct association between a genetic mutation of the NET and an autonomic clinical syndrome has recently emerged. A patient and her identical twin were evaluated for typical symptoms of orthostatic intolerance (OI), a disorder mainly characterised by elevated heart rate on standing, and both were found to have clinical and laboratory signs of abnormal uptake of NE. Sequence analysis of the patients' NET gene identified a mutation that resulted in more than 98% loss of function as compared with the wild-type gene. This article reconsiders the important role of the NET protein in the regulation of the nervous and cardiovascular systems, reviews the literature for its polymorphisms and their suggested clinical manifestations, and finally focuses on the effects of its defect on the pathophysiology of OI, the only confirmed direct association between a genetic mutation of the NET and a clinical syndrome.

The genetics of inflammatory bowel disease (IBD) is an area of enormous topical interest. Crohn's disease is one of the first polygenic diseases in which a susceptibility gene (NOD2) has been positionally cloned, providing proof of principle for methodologies that to date had been mired in uncertainty. IBD has been highly unusual among polygenic diseases in providing replicated candidate susceptibility regions using genome-scanning methodologies and linkage analysis. Such studies have identified loci with replicated evidence for linkage on chromosomes 1, 3, 6, 12, 14 and 16 – the latter recently yielding NOD2. The next stage is fine mapping each of the remaining candidate loci and identifying the precise genes involved. Although progress is slow, the identification of NOD2 together with technological advances and the availability of increasingly large panels of patients and multiply affected families provide the basis for great optimism. The ultimate goal is a better understanding of disease pathogenesis – both genetic and environmental – with a rational redefinition of Crohn's disease and ulcerative colitis, and a rational, specific therapeutic approach to each genotypically defined subclass of IBD.

A wide range of viruses, including many human and animal pathogens representing various taxonomic groups, contain genomes that are enclosed in lipid envelopes. These envelopes are generally acquired in the final stages of assembly, as viruses bud from regions of the membrane of the infected cell at which virally encoded membrane proteins have accumulated. The viruses procure their membranes during this process and mature particles ‘pinch off’ from the cellular membranes. Under most circumstances, initiation of another round of infection is dependent on two critical functions supplied by the envelope proteins. The virus must bind to cell-surface receptors of a new host cell, and fusion of the viral and cellular membranes must occur to transfer the viral genome into the cell. Enveloped viruses have evolved a variety of mechanisms to execute these two basic functions. Owing to their relative simplicity, studies of binding and fusion using enveloped viruses and their components have contributed significantly to the overall understanding of receptor–ligand interactions and membrane fusion processes – fundamental activities involved in a plethora of biological functions.

The early and clinically occult spread of viable tumour cells throughout the body is increasingly considered as a hallmark of cancer progression, because recent data suggest that these cells are precursors of subsequent distant relapse. Using monoclonal antibodies to epithelial cytokeratins or tumour-associated cell-membrane glycoproteins, individual carcinoma cells can be detected in cytological bone marrow preparations at frequencies of 10-5 to 10-6. Prospective clinical studies have shown that the presence of these immunostained micrometastatic cells in bone marrow, as a frequent site of overt metastases, is prognostically relevant with regard to relapse-free period and overall survival. This screening approach might therefore be used to improve tumour staging and to guide stratification of patients for adjuvant therapy in clinical trials. Another promising clinical application is the use of these micrometastatic cells to monitor response to adjuvant therapies, which at present can be assessed only retrospectively after an extended period of clinical follow-up. This review summarises current data on the clinical significance of occult metastatic breast cancer cells in bone marrow.