Ubiquitin immunostaining and inclusion body myositis: Study of 30 patients with inclusion body myositis

Distinction of inclusion body myositis (IBM) from other forms of inflammatory myopathy is significant from prognostic and therapeutic standpoints. This study retrospectively examines ubiquitin expression by paraffin immunohistochemistry in muscle biopsy material from 30 patients with IBM. Patients included 19 men and 11 women (ages 29 to 80 years; mean, 64 years). All biopsies were characterized by endomysial chronic inflammation, muscle fiber degeneration and regeneration, rimmed vacuoles, and angular atrophic esterase-positive muscle fibers. Ragged red fibers were identified in biopsies of five patients and a partial cytochrome C-oxidase deficiency by enzyme histochemistry in biopsies of 10 patients. Evidence of intranuclear or cytoplasmic tubulofilamentous structures confirming a diagnosis of IBM was observed in all 30 cases. Paracrystalline mitochondrial inclusions were noted in five patients. Discrete myocyte intranuclear ubiquitin-positive inclusions were noted in 14 patients (47%). Discrete intracytoplasmic ubiquitin-positive inclusions were noted in 24 (80%) patients. Positive staining of rimmed vacuoles by ubiquitin was observed in 25 (83%) patients. Diffuse staining of scattered muscle fibers was observed in 21 (70%) patients. In a control group including patients with polymyositis (n = 3), dermatomyositis (n = 3), necrotizing vasculitis (n = 1), and granulomatous myositis (n = 1), discrete intranuclear or cytoplasmic ubiquitin-positive inclusions were not observed. Rimmed vacuoles were not seen either by light microscopy or ubiquitin immunostaining in any of the eight cases. Occasional myofibers from all eight cases showed diffuse, positive muscle fiber staining. Although not present in all cases, evidence of ubiquitinpositive myocytic intranuclear or cytoplasmic inclusions or positive-staining rimmed vacuoles in the setting of an inflammatory myopathy may be suggestive of a diagnosis of inclusion body myositis. Use of ubiquitin immunohistochemistry may be useful in cases in which frozen tissue or tissue processed for electron microscopy is not available, and IBM is suspected. Light or electron microscopic evidence of mitochondrial abnormalities were noted in a significant subset of patients (13 of 30; 43%) of patients with IBM.     

Endoplasmic reticulum stress and the inflammatory response in allergic contact dermatitis

Maintaining homeostasis is central to organismal health. Deviation is detected by a variety of sensors that react to alarm signals arising from injury, infection, and other inflammatory triggers. One important element of this alarm system is the innate immune system, which recognizes pathogen-/microbe- or damage-associated molecular patterns via pattern recognition receptors localized in the cytosol or in membranes of innate immune cells such as macrophages, dendritic cells, and mast cells but also of T cells, B cells, and epithelial cells. Activation of the innate immune system results in inflammation and is a pre-requisite for activation of the adaptive immune system. Another important element is represented by the unfolded protein response (UPR), a stress response of the endoplasmic reticulum. The UPR regulates proteostasis and also contributes to the course of inflammatory diseases such as cancer, diabetes, obesity, and neurodegenerative diseases. In addition, the UPR is instrumental in allergic contact dermatitis. This inflammatory skin disease, affecting 5–10% of the population, is caused by T cells recognizing low-molecular weight organic chemicals and metal ions. In this mini-review, we discuss the orchestration of inflammatory responses by the interplay of the innate immune system with cellular stress responses in allergic contact dermatitis, with a focus on the UPR.     

Conspicuous accumulation of a single-stranded DNA binding protein in skeletal muscle fibers in inclusion body myositis.

In muscle biopsies from patients with inclusion body myositis (IBM), multiple sites were found in many muscle fibers that bound single-stranded but not double-stranded DNA without sequence specificity, as exemplified by several different cDNA probes. This activity was attributable to a protein, because it was abolished by proteases but not by RNAse. Most of the sites of binding were myonuclei, whereas some were rimmed vacuoles, which probably result from nuclear breakdown. No comparable binding was seen in 27 control biopsies. A number of human and viral single-stranded DNA binding proteins exist but our data does not identify the protein responsible for DNA binding in IBM. Our findings reinforce the supposition that nuclear damage plays a basic role in the pathogenesis of IBM.     

HLA associations with inclusion body myositis

Inclusion body myositis (IBM) is defined clinically by a characteristic pattern of progressive proximal and distal limb muscle weakness and resistance to steroid therapy, and histologically by the presence of distinctive rimmed vacuoles and filamentous inclusions as well as a mononuclear infiltrate in which CD8⁺ T cells are predominant. Muscle damage is believed to be mediated by autoimmune mechanisms, but very little information is available on the immunogenic features of IBM. MHC class I and DR antigens were typed on 13 caucasoid patients with IBM using standard serological techniques or by allele-specific oligonucleotide typing. Complement components C4 and properdin factor B (Bf) were typed by immunofixation after electrophoresis. Restriction fragment length polymorphisms (RFLP) in the class ITT region were analysed using cDNA probes for C4 and 21-hydroxylase (CYP21) after Taq 1 digestion. IBM was associated with DR3 (92%), DR52 (100%) and HLA B8 (75%). The phenotype data were examined for likely haplotypes by considering together the alleles at the class T, DR and complement loci along with the C4 and CYP21 RFLP. Ten of the DR3⁺ subjects had a 6 4-kb C4-hybridizing fragment characteristic of a deletion of C4A and CYP21-A. These patients probably carried all, or at least the class II and III regions, of the extended haplotype marked by B8/C4A*Q0/C4Bl/BfS/DR3/DR52, which has been associated with several autoimmune diseases and is present in 11% of the healthy Caucasoid population. Of the remaining subjects, two had evidence of the extended haplotype marked by B]8/C4A3/C4BQ*0/BfFl/DR3, which is present in less than 5% of the healthy population and has been associated with insulin-dependent diabetes mellitus. These data provide support for an autoimmune etiology for, and genetic predisposition to, IBM.     

Endoplasmic reticulum stress in autoimmune diseases

If the body's immune system is disordered and begins to attack “self” and therefore, its own tissues this is considered to be an autoimmune pathology. The specific mechanisms vary between the different diseases and have not always been elucidated but chronic, non-resolving inflammation is a common theme in the pathogenesis of autoimmune diseases. Interestingly, it has been shown that development and occurrence of various inflammatory responses are closely correlated to endoplasmic reticulum stress. Therefore, this review discusses the current progress of research about the relationship between autoimmune diseases and endoplasmic reticulum stress, specifically the unfolded protein response (UPR).     

Endoplasmic reticulum stress signaling in disease

The extracellular space is an environment hostile to unmodified polypeptides. For this reason, many eukaryotic proteins destined for exposure to this environment through secretion or display at the cell surface require maturation steps within a specialized organelle, the endoplasmic reticulum (ER). A complex homeostatic mechanism, known as the unfolded protein response (UPR), has evolved to link the load of newly synthesized proteins with the capacity of the ER to mature them. It has become apparent that dysfunction of the UPR plays an important role in some human diseases, especially those involving tissues dedicated to extracellular protein synthesis. Diabetes mellitus is an example of such a disease, since the demands for constantly varying levels of insulin synthesis make pancreatic beta-cells dependent on efficient UPR signaling. Furthermore, recent discoveries in this field indicate that the importance of the UPR in diabetes is not restricted to the beta-cell but is also involved in peripheral insulin resistance. This review addresses aspects of the UPR currently understood to be involved in human disease, including their role in diabetes mellitus, atherosclerosis, and neoplasia.     

Endoplasmic reticulum stress and intestinal inflammation

The intestinal epithelial cell (IEC) is increasingly recognized to play a prominent role as an important intermediary between the commensal microbiota and the intestinal immune system. Moreover, it is now recognized that intestinal inflammation in inflammatory bowel disease (IBD) may arise primarily from IEC dysfunction due to unresolved endoplasmic reticulum (ER) stress as a consequence of genetic disruption of X box binding protein-1 function. In addition to primary (genetic) abnormalities of the unfolded protein response, a variety of secondary (inflammation and environmental) factors are also likely to be important regulators of ER stress. ER stress pathways are also well known to regulate (and be regulated by) autophagy pathways. Therefore, the host's ability to manage ER stress is likely to be a major pathway in the pathogenesis of intestinal inflammation that arises primarily from the IEC. Herein we discuss ER stress in the IEC as both an originator and perpetuator of intestinal inflammation in IBD.     

内质网应激与心血管疾病

内质网应激是细胞内一种适应性机制,持续或过强的内质网应激则诱导细胞凋亡,造成组织损伤.多项研究显示内质网应激是多种心血管疾病如动脉粥样硬化、缺血性心脏病、心肌肥大、心力衰竭及糖尿痛心肌病等发生、发展的共同通路,干预内质网应激可能成为心血管疾病治疗的新靶点.     

内质网应激与prion疾病

1 引言 内质网(endoplasmic reticulum, ER)是真核细胞中钙离子贮存库,也是调节蛋白质合成及合成后加工、折叠和聚集的场所,是一种重要的细胞器.近年来,在生物医学研究领域中出现了一个新概念-"内质网应激"(ER stress),即:在饥饿、影响钙离子平衡的药物、影响蛋白质翻译后修饰、结构异常蛋白堆积以及一些有害因素等的诱发下,导致细胞内质网内稳态失衡、生理功能发生紊乱的一种亚细胞器的病理过程[1].     

The unfolded protein response--a stress signaling pathway of the endoplasmic reticulum

The endoplasmic reticulum (ER) is a factory for folding and maturation of newly synthesized transmembrane and secretory proteins. The ER provides stringent quality control systems to ensure that only correctly folded proteins exit the ER and unfolded or misfolded proteins are retained and ultimately degraded. A number of biochemical and physiological stimuli can change ER homeostasis, impose stress to the ER, and subsequently lead to accumulation of unfolded or misfolded proteins in the ER lumen. The ER has evolved stress response signaling pathways collectively called the unfolded protein response (UPR) to cope with the accumulation of unfolded or misfolded proteins. This review summarizes our understanding of the UPR signaling developed in the recent years.     

Endoplasmic reticulum stress signaling in pancreatic beta-cells

Pancreatic beta-cells are specialized for the production and regulated secretion of insulin to control blood-glucose levels. Increasing evidence indicates that stress-signaling pathways emanating from the endoplasmic reticulum (ER) are important in the maintenance of beta-cell homeostasis. Under physiological conditions, ER stress signaling has beneficial effects on beta-cells. Timely and proper activation of ER stress signaling is crucial for generating the proper amount of insulin in proportion to the need for it. In contrast, chronic and strong activation of ER stress signaling has harmful effects, leading to beta-cell dysfunction and death. Therefore, to dissect the molecular mechanisms of beta-cell failure and death in diabetes, it is necessary to understand the complex network of ER stress-signaling pathways. This review focuses on the function of the ER stress-signaling network in pancreatic beta-cells.     

内质网应激与缺血性心脏病

内质网应激(endoplasmic reticulum stress,ERS)与缺血性心脏病(ischemic heart disease,IHD)的发病机制密切相关。内质网应激的保护机制有利于心肌细胞应付缺血、维持细胞稳态;而过度内质网应激引起的损伤机制则在心肌缺血后心肌细胞凋亡中发挥了重要作用。本文主要就内质网应激及缺血性心脏病的研究进展作一综述,为缺血性心脏病发病机制的研究及临床治疗提供新的理论依据。     

内质网应激反应与相关分子伴侣

多种生理或病理条件会引起未折叠蛋白或错误折叠蛋白在内质网的聚集,损伤内质网的正常生理功能,此现象称为内质网应激(endoplasmic reticulum stress,ERS)。ERS时,许多分子伴侣蛋白,如:葡萄糖调节蛋白、钙联蛋白以及钙网蛋白等的表达出现上调,参与调控ERS过程,甚至启动caspase 12、CHOP/GADDl53等促凋亡因子表达和活化。目前,对一些疾病,如:酒精性肝病和阿尔兹海默病等的研究表明,疾病的病理机制中可见内质网分子伴侣的表达变化,提示疾病的发生与ERS可能有相关性。本文旨在对与ERS相关的分子伴侣的基本结构和调控过程以及相关疾病的病理机制进行综述。     

Serial quantitative electrophysiologic studies in sporadic inclusion body myositis

Sporadic inclusion body myositis (S-IBM) is a progressive, acquired myopathic process of unknown etiology. No known, successful or proven treatment exists. Quantitative EMG studies including concentric needle motor unit action potentials, interference pattern, macro-EMG and fiber density have allowed different measures to be made of the motor unit. These different measures allow inferences to be made in how the muscle fibers are distributed within both the normal and diseased motor unit. The present study is an effort to use multiple quantitative EMG measurements from the biceps brachii on a serial basis in order to study chronic changes in the motor unit with disease progression. Twenty-eight studies from 9 patients over a four-year period are shown. We conclude that while the concentric needle electrode is most helpful for diagnosing abnormality, the less selective macro-EMG and surface electrodes are better suited to monitor disease progression, especially in very weak muscles. These observations have practical applications for monitoring disease progression, or conversely, response to treatment.