Annu Rev Pathol
· 2019 Jan · PMID 30148688
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Obligately intracytosolic rickettsiae that cycle between arthropod and vertebrate hosts cause human diseases with a spectrum of severity, primarily by targeting microvascular endothelial cells, resulting in endothelial d...Obligately intracytosolic rickettsiae that cycle between arthropod and vertebrate hosts cause human diseases with a spectrum of severity, primarily by targeting microvascular endothelial cells, resulting in endothelial dysfunction. Endothelial cells and mononuclear phagocytes have important roles in the intracellular killing of rickettsiae upon activation by the effector molecules of innate and adaptive immunity. In overwhelming infection, immunosuppressive effects contribute to the severity of illness. Rickettsia-host cell interactions involve host cell receptors for rickettsial ligands that mediate cell adhesion and, in some instances, trigger induced phagocytosis. Rickettsiae interact with host cell actin to effect both cellular entry and intracellular actin-based mobility. The interaction of rickettsiae with the host cell also involves rickettsial evasion of host defense mechanisms and exploitation of the intracellular environment. Signal transduction events exemplify these effects. An intriguing frontier is the array of rickettsial noncoding RNA molecules and their potential effects on the pathogenesis and transmission of rickettsial diseases.
Shahnoor N, Siebers EM, Brown KJ
… +1 more, Lawlor MW
Annu Rev Pathol
· 2019 Jan · PMID 30148687
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Dystrophinopathy is a class of genetic skeletal muscle disease characterized by myofiber degeneration and regeneration due to insufficient levels or functioning of dystrophin. Pathological evaluation for dystrophinopathy...Dystrophinopathy is a class of genetic skeletal muscle disease characterized by myofiber degeneration and regeneration due to insufficient levels or functioning of dystrophin. Pathological evaluation for dystrophinopathy includes the identification of dystrophic skeletal muscle pathology and the immunohistochemical evaluation of dystrophin epitopes, but biopsies have become rare in recent years. However, the evaluation of dystrophin expression in the research setting has become critically important due to recent advances in genetic therapies, including exon skipping and gene therapy. Given the number of these therapies under evaluation in patients, it is likely that the traditional methods of evaluating dystrophinopathy will need to evolve in the near future. This review discusses current muscle biopsy diagnostic practices in dystrophinopathy and further focuses on how these practices have evolved in the context of therapeutic interventions for dystrophinopathy.
Ogino S, Nowak JA, Hamada T
… +2 more, Milner DA, Nishihara R
Annu Rev Pathol
· 2019 Jan · PMID 30125150
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Evidence indicates that diet, nutrition, lifestyle, the environment, the microbiome, and other exogenous factors have pathogenic roles and also influence the genome, epigenome, transcriptome, proteome, and metabolome of...Evidence indicates that diet, nutrition, lifestyle, the environment, the microbiome, and other exogenous factors have pathogenic roles and also influence the genome, epigenome, transcriptome, proteome, and metabolome of tumor and nonneoplastic cells, including immune cells. With the need for big-data research, pathology must transform to integrate data science fields, including epidemiology, biostatistics, and bioinformatics. The research framework of molecular pathological epidemiology (MPE) demonstrates the strengths of such an interdisciplinary integration, having been used to study breast, lung, prostate, and colorectal cancers. The MPE research paradigm not only can provide novel insights into interactions among environment, tumor, and host but also opens new research frontiers. New developments-such as computational digital pathology, systems biology, artificial intelligence, and in vivo pathology technologies-will further transform pathology and MPE. Although it is necessary to address the rarity of transdisciplinary education and training programs, MPE provides an exemplary model of integrative scientific approaches and contributes to advancements in precision medicine, therapy, and prevention.
Annu Rev Pathol
· 2019 Jan · PMID 30125149
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Epstein-Barr virus (EBV) contributes to about 1.5% of all cases of human cancer worldwide, and viral genes are expressed in the malignant cells. EBV also very efficiently causes the proliferation of infected human B lymp...Epstein-Barr virus (EBV) contributes to about 1.5% of all cases of human cancer worldwide, and viral genes are expressed in the malignant cells. EBV also very efficiently causes the proliferation of infected human B lymphocytes. The functions of the viral proteins and small RNAs that may contribute to EBV-associated cancers are becoming increasingly clear, and a broader understanding of the sequence variation of the virus genome has helped to interpret their roles. The improved understanding of the mechanisms of these cancers means that there are great opportunities for the early diagnosis of treatable stages of EBV-associated cancers and the use of immunotherapy to target EBV-infected cells or overcome immune evasion. There is also scope for preventing disease by immunization and for developing therapeutic agents that target the EBV gene products expressed in the cancers.
Annu Rev Pathol
· 2019 Jan · PMID 30125148
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This review focuses primarily on the beneficial effects for human health of exposure to ultraviolet radiation (UVR). UVR stimulates anti-inflammatory and immunosuppressive pathways in skin that modulate psoriasis, atopic...This review focuses primarily on the beneficial effects for human health of exposure to ultraviolet radiation (UVR). UVR stimulates anti-inflammatory and immunosuppressive pathways in skin that modulate psoriasis, atopic dermatitis, and vitiligo; suppresses cutaneous lesions of graft-versus-host disease; and regulates some infection and vaccination outcomes. While polymorphic light eruption and the cutaneous photosensitivity of systemic lupus erythematosus are triggered by UVR, polymorphic light eruption also frequently benefits from UVR-induced immunomodulation. For systemic diseases such as multiple sclerosis, type 1 diabetes, asthma, schizophrenia, autism, and cardiovascular disease, any positive consequences of UVR exposure are more speculative, but could occur through the actions of UVR-induced regulatory cells and mediators, including 1,25-dihydroxy vitamin D, interleukin-10, and nitric oxide. Reduced UVR exposure is a risk factor for the development of several inflammatory, allergic, and autoimmune conditions, including diseases initiated in early life. This suggests that UVR-induced molecules can regulate cell maturation in developing organs.
Annu Rev Pathol
· 2019 Jan · PMID 30089230
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Among the age-dependent protein aggregation disorders, nine neurodegenerative diseases are caused by expansions of CAG repeats encoding polyglutamine (polyQ) tracts. We review the clinical, pathological, and biological f...Among the age-dependent protein aggregation disorders, nine neurodegenerative diseases are caused by expansions of CAG repeats encoding polyglutamine (polyQ) tracts. We review the clinical, pathological, and biological features of these inherited disorders. We discuss insights into pathogenesis gleaned from studies of model systems and patients, highlighting work that informs efforts to develop effective therapies. An important conclusion from these analyses is that expanded CAG/polyQ domains are the primary drivers of neurodegeneration, with the biology of carrier proteins influencing disease-specific manifestations. Additionally, it has become apparent that CAG/polyQ repeat expansions produce neurodegeneration via multiple downstream mechanisms, involving both gain- and loss-of-function effects. This conclusion indicates that the likelihood of developing effective therapies targeting single nodes is reduced. The evaluation of treatments for premanifest disease will likely require new investigational approaches. We highlight the opportunities and challenges underlying ongoing work and provide recommendations related to the development of symptomatic and disease-modifying therapies and biomarkers that could inform future research.
Annu Rev Pathol
· 2018 Jan · PMID 29414251
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Peripheral T cell lymphomas (PTCLs) are highly heterogeneous tumors, displaying distinct clinical and biological features. The pathogenesis and normal counterpart of such entities have been elusive for decades. Recent st...Peripheral T cell lymphomas (PTCLs) are highly heterogeneous tumors, displaying distinct clinical and biological features. The pathogenesis and normal counterpart of such entities have been elusive for decades. Recent studies have, however, disclosed key mechanisms of peripheral T cell transformation, including (a) the deregulation of signaling pathways controlling T cell development, differentiation, and maturation; (b) the remodeling of the peritumor microenvironment; and (c) the virus-mediated rewiring of T cell biology. Uncovering the molecular mechanisms of T cell transformation will help elucidate the peculiar clinical and pathological features of each PTCL entity and will lead to the characterization of novel antitumor therapies. These therapies will combine conventional and new-generation compounds with immune-modulating agents to ablate both the neoplastic cells and the tumor-supporting microenvironment. This review addresses the pathogenic mechanisms of PTCLs, with special attention paid to novel therapeutic strategies for the clinical management of such aggressive tumors.
Annu Rev Pathol
· 2018 Jan · PMID 29414250
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Tissue integrity is crucial for maintaining the homeostasis of living organisms. Abnormalities that affect sites of cell-cell contact can cause a variety of debilitating disorders. The desmosome is an essential cell-cell...Tissue integrity is crucial for maintaining the homeostasis of living organisms. Abnormalities that affect sites of cell-cell contact can cause a variety of debilitating disorders. The desmosome is an essential cell-cell junctional protein complex in tissues that undergo stress, and it orchestrates intracellular signal transduction. Desmosome assembly and junctional integrity are required to maintain the overall homeostasis of a tissue, organ, and organism. This review discusses the desmosome and the human diseases associated with its disruption.
Annu Rev Pathol
· 2018 Jan · PMID 29414249
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Nonalcoholic fatty liver disease (NAFLD) is a burgeoning health problem worldwide and an important risk factor for both hepatic and cardiometabolic mortality. The rapidly increasing prevalence of this disease and of its...Nonalcoholic fatty liver disease (NAFLD) is a burgeoning health problem worldwide and an important risk factor for both hepatic and cardiometabolic mortality. The rapidly increasing prevalence of this disease and of its aggressive form nonalcoholic steatohepatitis (NASH) will require novel therapeutic approaches based on a profound understanding of its pathogenesis to halt disease progression to advanced fibrosis or cirrhosis and cancer. The pathogenesis of NAFLD involves a complex interaction among environmental factors (i.e., Western diet), obesity, changes in microbiota, and predisposing genetic variants resulting in a disturbed lipid homeostasis and an excessive accumulation of triglycerides and other lipid species in hepatocytes. Insulin resistance is a central mechanism that leads to lipotoxicity, endoplasmic reticulum stress, disturbed autophagy, and, ultimately, hepatocyte injury and death that triggers hepatic inflammation, hepatic stellate cell activation, and progressive fibrogenesis, thus driving disease progression. In the present review, we summarize the currently available data on the pathogenesis of NAFLD, emphasizing the most recent advances. A better understanding of NAFLD/NASH pathogenesis is crucial for the design of new and efficient therapeutic interventions.
Annu Rev Pathol
· 2018 Jan · PMID 29414248
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Metastasis is the major cause of cancer-related deaths; therefore, the prevention and treatment of metastasis are fundamental to improving clinical outcomes. Epithelial mesenchymal transition (EMT), an evolutionarily con...Metastasis is the major cause of cancer-related deaths; therefore, the prevention and treatment of metastasis are fundamental to improving clinical outcomes. Epithelial mesenchymal transition (EMT), an evolutionarily conserved developmental program, has been implicated in carcinogenesis and confers metastatic properties upon cancer cells by enhancing mobility, invasion, and resistance to apoptotic stimuli. Furthermore, EMT-derived tumor cells acquire stem cell properties and exhibit marked therapeutic resistance. Given these attributes, the complex biological process of EMT has been heralded as a key hallmark of carcinogenesis, and targeting EMT pathways constitutes an attractive strategy for cancer treatment. However, demonstrating the necessity of EMT for metastasis in vivo has been technically challenging, and recent efforts to demonstrate a functional contribution of EMT to metastasis have yielded unexpected results. Therefore, determining the functional role of EMT in metastasis remains an area of active investigation. Studies using improved lineage tracing systems, dynamic in vivo imaging, and clinically relevant in vivo models have the potential to uncover the direct link between EMT and metastasis. This review focuses primarily on recent advances in and emerging concepts of the biology of EMT in metastasis in vivo and discusses future directions in the context of novel diagnostic and therapeutic opportunities.
Annu Rev Pathol
· 2018 Jan · PMID 29414247
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From injury to disease to aging, neurons, like all cells, may face various insults that can impact their function and survival. Although the consequences are substantially dictated by the type, context, and severity of i...From injury to disease to aging, neurons, like all cells, may face various insults that can impact their function and survival. Although the consequences are substantially dictated by the type, context, and severity of insult, distressed neurons are far from passive. Activation of cellular stress responses aids in the preservation or restoration of nervous system function. However, stress responses themselves can further advance neuropathology and contribute significantly to neuronal dysfunction and neurodegeneration. Here we explore the recent advances in defining the cellular stress responses within neurodegenerative diseases and neuronal injury, and we emphasize axonal injury as a well-characterized model of neuronal insult. We highlight key findings and unanswered questions about neuronal stress response pathways, from the initial detection of cellular insults through the underlying mechanisms of the responses to their ultimate impact on the fates of distressed neurons.
Annu Rev Pathol
· 2018 Jan · PMID 29414246
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These words reflect my recollections of major transition points in my life and career: as I first became dedicated to becoming a physician, being introduced to the field of pathology and research, and then transitioning...These words reflect my recollections of major transition points in my life and career: as I first became dedicated to becoming a physician, being introduced to the field of pathology and research, and then transitioning to a somewhat different career focus by becoming the first director of the National Institutes of Health Office of Research on Women's Health. Many of the experiences that I gained during my years in pathology served me well as I made efforts to establish women's health research and sex and gender based studies as scientific endeavors. Participating in research and teaching as an academic pathologist, setting funding priorities, and supporting and encouraging research careers through governmental office programs have been the essence of my more than 50 years as a pathologist and physician.
Annu Rev Pathol
· 2018 Jan · PMID 29195051
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The central nervous system (CNS) is unique in being the only organ system lacking lymphatic vessels to assist in the removal of interstitial metabolic waste products. Recent work has led to the discovery of the glymphati...The central nervous system (CNS) is unique in being the only organ system lacking lymphatic vessels to assist in the removal of interstitial metabolic waste products. Recent work has led to the discovery of the glymphatic system, a glial-dependent perivascular network that subserves a pseudolymphatic function in the brain. Within the glymphatic pathway, cerebrospinal fluid (CSF) enters the brain via periarterial spaces, passes into the interstitium via perivascular astrocytic aquaporin-4, and then drives the perivenous drainage of interstitial fluid (ISF) and its solute. Here, we review the role of the glymphatic pathway in CNS physiology, the factors known to regulate glymphatic flow, and the pathologic processes in which a breakdown of glymphatic CSF-ISF exchange has been implicated in disease initiation and progression. Important areas of future research, including manipulation of glymphatic activity aiming to improve waste clearance and therapeutic agent delivery, are also discussed.
Annu Rev Pathol
· 2018 Jan · PMID 29140757
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Lymphomas represent clonal proliferations of lymphocytes that are broadly classified based upon their maturity (peripheral or mature versus precursor) and lineage (B cell, T cell, and natural killer cell). Insights into...Lymphomas represent clonal proliferations of lymphocytes that are broadly classified based upon their maturity (peripheral or mature versus precursor) and lineage (B cell, T cell, and natural killer cell). Insights into the pathogenetic mechanisms involved in lymphoma impact the classification of lymphoma and have significant implications for the diagnosis and clinical management of patients. Serial scientific and technologic advances over the last 30 years in immunology, cytogenetics, molecular biology, gene expression profiling, mass spectrometry-based proteomics, and, more recently, next-generation sequencing have contributed to greatly enhance our understanding of the pathogenetic mechanisms in lymphoma. Novel and emerging concepts that challenge our previously accepted paradigms about lymphoma biology and how these impact diagnosis, molecular testing, disease monitoring, drug development, and personalized and precision medicine for lymphoma are discussed.
Webb GJ, Hirschfield GM, Krawitt EL
… +1 more, Gershwin ME
Annu Rev Pathol
· 2018 Jan · PMID 29140756
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Autoimmune hepatitis is an uncommon idiopathic syndrome of immune-mediated destruction of hepatocytes, typically associated with autoantibodies. The disease etiology is incompletely understood but includes a clear associ...Autoimmune hepatitis is an uncommon idiopathic syndrome of immune-mediated destruction of hepatocytes, typically associated with autoantibodies. The disease etiology is incompletely understood but includes a clear association with human leukocyte antigen (HLA) variants and other non-HLA gene variants, female sex, and the environment. Pathologically, there is a CD4+ T cell-rich lymphocytic inflammatory infiltrate with variable hepatocyte necrosis and subsequent hepatic fibrosis. Attempts to understand pathogenesis are informed by several monogenetic syndromes that may include autoimmune liver injury, by several drug and environmental agents that have been identified as triggers in a minority of cases, by human studies that point toward a central role for CD4+ effector and regulatory T cells, and by animal models of the disease. Nonspecific immunosuppression is the current standard therapy. Further understanding of the disease's cellular and molecular mechanisms may assist in the design of better-targeted therapies, aid the limitation of adverse effects from therapy, and inform individualized risk assessment and prognostication.
Annu Rev Pathol
· 2018 Jan · PMID 29125798
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The liver is an organ that performs a multitude of functions, and its health is pertinent and indispensable to survival. Thus, the cellular and molecular machinery driving hepatic functions is of utmost relevance. The Wn...The liver is an organ that performs a multitude of functions, and its health is pertinent and indispensable to survival. Thus, the cellular and molecular machinery driving hepatic functions is of utmost relevance. The Wnt signaling pathway is one such signaling cascade that enables hepatic homeostasis and contributes to unique hepatic attributes such as metabolic zonation and regeneration. The Wnt/β-catenin pathway plays a role in almost every facet of liver biology. Furthermore, its aberrant activation is also a hallmark of various hepatic pathologies. In addition to its signaling function, β-catenin also plays a role at adherens junctions. Wnt/β-catenin signaling also influences the function of many different cell types. Due to this myriad of functions, Wnt/β-catenin signaling is complex, context-dependent, and highly regulated. In this review, we discuss the Wnt/β-catenin signaling pathway, its role in cell-cell adhesion and liver function, and the cell type-specific roles of Wnt/β-catenin signaling as it relates to liver physiology and pathobiology.
Kuszak AJ, Espey MG, Falk MJ
… +5 more, Holmbeck MA, Manfredi G, Shadel GS, Vernon HJ, Zolkipli-Cunningham Z
Annu Rev Pathol
· 2018 Jan · PMID 29099651
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Multisystem metabolic disorders caused by defects in oxidative phosphorylation (OXPHOS) are severe, often lethal, conditions. Inborn errors of OXPHOS function are termed primary mitochondrial disorders (PMDs), and the us...Multisystem metabolic disorders caused by defects in oxidative phosphorylation (OXPHOS) are severe, often lethal, conditions. Inborn errors of OXPHOS function are termed primary mitochondrial disorders (PMDs), and the use of nutritional interventions is routine in their supportive management. However, detailed mechanistic understanding and evidence for efficacy and safety of these interventions are limited. Preclinical cellular and animal model systems are important tools to investigate PMD metabolic mechanisms and therapeutic strategies. This review assesses the mechanistic rationale and experimental evidence for nutritional interventions commonly used in PMDs, including micronutrients, metabolic agents, signaling modifiers, and dietary regulation, while highlighting important knowledge gaps and impediments for randomized controlled trials. Cellular and animal model systems that recapitulate mutations and clinical manifestations of specific PMDs are evaluated for their potential in determining pathological mechanisms, elucidating therapeutic health outcomes, and investigating the value of nutritional interventions for mitochondrial disease conditions.
Annu Rev Pathol
· 2018 Jan · PMID 29099650
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Allogeneic transplantation of foreign organs or tissues has lifesaving potential, but can lead to serious complications. After solid organ transplantation, immune-mediated rejection mandates the use of prolonged global i...Allogeneic transplantation of foreign organs or tissues has lifesaving potential, but can lead to serious complications. After solid organ transplantation, immune-mediated rejection mandates the use of prolonged global immunosuppression and limits the life span of transplanted allografts. After bone marrow transplantation, donor-derived immune cells can trigger life-threatening graft-versus-host disease. T cells are central mediators of alloimmune complications and the target of most existing therapeutic interventions. We review recent progress in identifying multiple cell types in addition to T cells and new molecular pathways that regulate pathogenic alloreactivity. Key discoveries include the cellular subsets that function as potential sources of alloantigens, the cross talk of innate lymphoid cells with damaged epithelia and with the recipient microbiome, the impact of the alarmin interleukin-33 on alloreactivity, and the role of Notch ligands expressed by fibroblastic stromal cells in alloimmunity. While refining our understanding of transplantation immunobiology, these findings identify new therapeutic targets and new areas of investigation.
Annu Rev Pathol
· 2018 Jan · PMID 29083981
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The genomic landscape of thyroid cancers that are derived from follicular cells has been substantially elucidated through the coordinated application of high-throughput genomic technologies. Here, I review the common gen...The genomic landscape of thyroid cancers that are derived from follicular cells has been substantially elucidated through the coordinated application of high-throughput genomic technologies. Here, I review the common genetic alterations across the spectrum of thyroid neoplasia and present the resulting model of thyroid cancer initiation and progression. This model illustrates the striking correlation between tumor differentiation and overall somatic mutational burden, which also likely explains the highly variable clinical behavior and outcome of patients with thyroid cancers. These advances are yielding critical insights into thyroid cancer pathogenesis, which are being leveraged for the development of new diagnostic tools, prognostic and predictive biomarkers, and novel therapeutic approaches.
Annu Rev Pathol
· 2018 Jan · PMID 29068753
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Metastases are responsible for the vast majority of cancer-related deaths, but, despite intense efforts to understand their underlying mechanisms with the goal of uncovering effective therapeutic targets, treatment of me...Metastases are responsible for the vast majority of cancer-related deaths, but, despite intense efforts to understand their underlying mechanisms with the goal of uncovering effective therapeutic targets, treatment of metastatic cancer has progressed minimally. In this review, we examine the biological programs currently proposed to be key drivers of metastasis. On the basis of evidence from a growing body of research, we discuss to what extent the cellular and molecular mechanisms that are suggested to underlie cancer cell dissemination are specific to the metastatic process, as opposed to representing natural primary tumor progression. Our review highlights the contrast between the abundance of insight gained into the events that constitute the metastatic cascade and the paucity of therapeutic options.