scholarly journals Pathogenesis of Autoimmune Hepatitis—Cellular and Molecular Mechanisms

2021 ◽  
Vol 22 (24) ◽  
pp. 13578
Author(s):  
Claudia Sirbe ◽  
Gelu Simu ◽  
Iulia Szabo ◽  
Alina Grama ◽  
Tudor Lucian Pop
Keyword(s):  
Autoimmune Hepatitis ◽  
Molecular Mechanisms ◽  
Viral Infections ◽  
De Novo ◽  
Molecular Mimicry ◽  
Treg Cells ◽  
Clinical Aspects ◽  
Autoantibody Production ◽  
Genetic Traits ◽  
First Line Therapy

Pediatric autoimmune liver disorders include autoimmune hepatitis (AIH), autoimmune sclerosing cholangitis (ASC), and de novo AIH after liver transplantation. AIH is an idiopathic disease characterized by immune-mediated hepatocyte injury associated with the destruction of liver cells, causing inflammation, liver failure, and fibrosis, typically associated with autoantibodies. The etiology of AIH is not entirely unraveled, but evidence supports an intricate interaction among genetic variants, environmental factors, and epigenetic modifications. The pathogenesis of AIH comprises the interaction between specific genetic traits and molecular mimicry for disease development, impaired immunoregulatory mechanisms, including CD4+ T cell population and Treg cells, alongside other contributory roles played by CD8+ cytotoxicity and autoantibody production by B cells. These findings delineate an intricate pathway that includes gene to gene and gene to environment interactions with various drugs, viral infections, and the complex microbiome. Epigenetics emphasizes gene expression through hereditary and reversible modifications of the chromatin architecture without interfering with the DNA sequence. These alterations comprise DNA methylation, histone transformations, and non-coding small (miRNA) and long (lncRNA) RNA transcriptions. The current first-line therapy comprises prednisolone plus azathioprine to induce clinical and biochemical remission. Further understanding of the cellular and molecular mechanisms encountered in AIH may depict their impact on clinical aspects, detect biomarkers, and guide toward novel, effective, and better-targeted therapies with fewer side effects.

scholarly journals Viruses and Autoimmunity: A Review on the Potential Interaction and Molecular Mechanisms

Viruses ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 762 ◽  
Author(s):  
Maria K. Smatti ◽  
Farhan S. Cyprian ◽  
Gheyath K. Nasrallah ◽  
Asmaa A. Al Thani ◽  
Ruba O. Almishal ◽  
...  
Keyword(s):  
Immune Responses ◽  
Autoimmune Diseases ◽  
Lupus Erythematosus ◽  
Influenza A ◽  
Molecular Mechanisms ◽  
Viral Infections ◽  
Molecular Mimicry ◽  
Experimental Studies ◽  
Onset Time ◽  
Protective Effects

For a long time, viruses have been shown to modify the clinical picture of several autoimmune diseases, including type 1 diabetes (T1D), systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), Sjögren’s syndrome (SS), herpetic stromal keratitis (HSK), celiac disease (CD), and multiple sclerosis (MS). Best examples of viral infections that have been proposed to modulate the induction and development of autoimmune diseases are the infections with enteric viruses such as Coxsackie B virus (CVB) and rotavirus, as well as influenza A viruses (IAV), and herpesviruses. Other viruses that have been studied in this context include, measles, mumps, and rubella. Epidemiological studies in humans and experimental studies in animal have shown that viral infections can induce or protect from autoimmunopathologies depending on several factors including genetic background, host-elicited immune responses, type of virus strain, viral load, and the onset time of infection. Still, data delineating the clear mechanistic interaction between the virus and the immune system to induce autoreactivity are scarce. Available data indicate that viral-induced autoimmunity can be activated through multiple mechanisms including molecular mimicry, epitope spreading, bystander activation, and immortalization of infected B cells. Contrarily, the protective effects can be achieved via regulatory immune responses which lead to the suppression of autoimmune phenomena. Therefore, a better understanding of the immune-related molecular processes in virus-induced autoimmunity is warranted. Here we provide an overview of the current understanding of viral-induced autoimmunity and the mechanisms that are associated with this phenomenon.

Molecular Basis and Clinical Aspects of Hereditary Megakaryocyte and Platelet Membrane Glycoprotein Disorders

1996 ◽  
Vol 16 (02) ◽  
pp. 114-138 ◽  
Author(s):  
R. E. Scharf
Keyword(s):  
Genetic Basis ◽  
Molecular Mechanisms ◽  
Molecular Genetic ◽  
Platelet Membrane ◽  
Clinical Aspects ◽  
Membrane Glycoprotein ◽  
Membrane Glycoproteins ◽  
Membrane Expression ◽  
Receptor Complexes ◽  
Platelet Membrane Glycoprotein

SummarySpecific membrane glycoproteins (GP) expressed by the megakaryocyte-platelet system, including GPIa-lla, GPIb-V-IX, GPIIb-llla, and GPIV are involved in mediat-ing platelet adhesion to the subendothelial matrix. Among these glycoproteins, GPIIb-llla plays a pivotal role since platelet aggregation is exclusively mediated by this receptor and its interaction with soluble macromolecular proteins. Inherited defects of the GPIIb-llla or GPIb-V-IX receptor complexes are associated with bleeding disorders, known as Glanzmann's thrombasthenia, Bernard-Soulier syndrome, or platelet-type von Willebrand's disease, respectively. Using immuno-chemical and molecular biology techniques, rapid advances in our understanding of the molecular genetic basis of these disorders have been made during the last few years. Moreover, analyses of patients with congenital platelet membrane glycoprotein abnormalities have provided valuable insights into molecular mechanisms that are required for structural and functional integrity, normal biosynthesis of the glycoprotein complexes and coordinated membrane expression of their constituents. The present article reviews the current state of knowledge of the major membrane glycoproteins in health and disease. The spectrum of clinical bleeding manifestations and established diagnostic criteria for each of these dis-orders are summarized. In particular, the variety of molecular defects that have been identified so far and their genetic basis will be discussed.

Polymyalgia Rheumatica - a Disease of the Elderly

2018 ◽  
Vol 69 (1) ◽  
pp. 152-154
Author(s):  
Vasilica Cristescu ◽  
Aurelia Romila ◽  
Luana Andreea Macovei
Keyword(s):  
Giant Cell Arteritis ◽  
Giant Cell ◽  
Polymyalgia Rheumatica ◽  
Temporal Arteritis ◽  
Viral Infections ◽  
Clinical Manifestations ◽  
The Elderly ◽  
Clinical Aspects ◽  
Immune Disorder ◽  
Markers Of Inflammation

Polymyalgia rheumatica is a disease that occurs mostly in the elderly and is rarely seen in patients less than 50 years of age. Polymyalgia rheumatica is a vasculitis, which manifests itself as an inflammatory disease of the vascular wall that can affect any type of blood vessel, regardless of its size. It has been considered a form of giant cell arteritis, involving primarily large and medium arteries and to a lesser extent the arterioles. Clinical manifestations are caused by the generic pathogenic process and depend on the characteristics of the damaged organ. PMR is a senescence-related immune disorder. It has been defined as a stand-alone condition and a syndrome referred to as rheumatic polyarteritis with manifestations of giant cell arteritis (especially in cases of Horton�s disease and temporal arteritis) which are commonly associated with polymyalgia. The clinical presentation is clearly dominated by the painful girdle syndrome, with a feeling of general discomfort. Polymyalgia and temporal arteritis may coexist or be consecutive to each other in the same patient, as in most of our patients. The present study describes 3 cases of polymyalgia rheumatica, admitted to the Clinic of Rheumatology of Sf. Apostol Andrei Hospital, Galati. The cases were compared with the literature. Two clinical aspects (polymyalgia rheumatica and/or Horton�s disease) and the relationship between them were also considered. Polymyalgia rheumatica is currently thought to have a multifactorial etiology, in which the following factors play a role: genetic factors or hereditary predisposition (some individuals are more prone to this disease), immune factors and viral infections (triggers of the disease). Other risk factors of polymyalgia rheumatica include age over 50 years and the association with giant cell arteritis. The characteristic feature of the disease is girdle pain, with intense stiffness of at least one hour�s duration. Markers of inflammation, erythrocyte sedimentation rate and C-reactive protein are almost always increased at the onset of the disease. Diseases that can mimic the clinical picture of polymyalgia rheumatica are neoplasia, infections, metabolic disorders of the bone and endocrine diseases.

Expression and Significance of Th17 Cells and Related Factors in Patients with Autoimmune Hepatitis

2019 ◽  
Vol 22 (4) ◽  
pp. 232-237 ◽  
Author(s):  
Jihong An
Keyword(s):  
Autoimmune Hepatitis ◽  
Peripheral Blood ◽  
Th17 Cells ◽  
Treg Cells ◽  
Enzyme Linked Immunosorbent Assay ◽  
Control Group ◽  
Serum Total Bilirubin ◽  
Study Group ◽  
Related Factors ◽  
Tnf Α

Objective: This study aims to investigate the expression and clinical significance of Th17 cells and related factors in peripheral blood of patients with Autoimmune Hepatitis (AIH). Methods: A retrospective selection of 100 patients with AIH were included as a study group, and 100 healthy volunteers in the outpatient clinic were selected as the control group. The levels of IL- 17, IL-6, IL-21 and TNF-α in peripheral blood of all subjects were detected by enzyme-linked immunosorbent assay and the frequency of Th17 cells and Treg cells was detected by flow cytometry. Results: Results showed that the study group had higher levels of serum total bilirubin (TBil), alkaline phosphatase (ALP), γ -glutamyltranspeptidase (γ-GT), immunoglobulin G (IgG), immunoglobulin M (IgM), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) than the control group, as well as higher levels of IL-17, IL-6, IL-21 and TNF-α in serum. The frequency of Th17 cells in peripheral blood was higher in the study group, while the frequency of Treg cells was lower. Also, serum IL-17, TNF-α levels and Th17 cells frequency were positively correlated with ALT and AST, whereas Treg cells frequency were negatively correlated with ALT and AST levels. Conclusion: Our finding demonstrates that Th17 cell frequency and their related factors IL-17 and TNF-α, are associated with liver damage, which might be used to monitor AIH disease severity.

scholarly journals HP1 drives de novo 3D genome reorganization in early Drosophila embryos

Nature ◽  
2021 ◽  
Author(s):  
Fides Zenk ◽  
Yinxiu Zhan ◽  
Pavel Kos ◽  
Eva Löser ◽  
Nazerke Atinbayeva ◽  
...  
Keyword(s):  
Genome Organization ◽  
Molecular Mechanisms ◽  
High Throughput Sequencing ◽  
De Novo ◽  
Early Embryo ◽  
Heterochromatin Protein ◽  
Chromosome Conformation ◽  
3D Genome ◽  
Genome Reorganization

AbstractFundamental features of 3D genome organization are established de novo in the early embryo, including clustering of pericentromeric regions, the folding of chromosome arms and the segregation of chromosomes into active (A-) and inactive (B-) compartments. However, the molecular mechanisms that drive de novo organization remain unknown1,2. Here, by combining chromosome conformation capture (Hi-C), chromatin immunoprecipitation with high-throughput sequencing (ChIP–seq), 3D DNA fluorescence in situ hybridization (3D DNA FISH) and polymer simulations, we show that heterochromatin protein 1a (HP1a) is essential for de novo 3D genome organization during Drosophila early development. The binding of HP1a at pericentromeric heterochromatin is required to establish clustering of pericentromeric regions. Moreover, HP1a binding within chromosome arms is responsible for overall chromosome folding and has an important role in the formation of B-compartment regions. However, depletion of HP1a does not affect the A-compartment, which suggests that a different molecular mechanism segregates active chromosome regions. Our work identifies HP1a as an epigenetic regulator that is involved in establishing the global structure of the genome in the early embryo.

scholarly journals Copy number-dependent DNA methylation of the Pyricularia oryzae MAGGY retrotransposon is triggered by DNA damage

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Ba Van Vu ◽  
Quyet Nguyen ◽  
Yuki Kondo-Takeoka ◽  
Toshiki Murata ◽  
Naoki Kadotani ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Copy Number ◽  
Rna Silencing ◽  
Molecular Mechanisms ◽  
De Novo ◽  
Pyricularia Oryzae ◽  
Transcriptional Gene Silencing ◽  
Physical Interaction ◽  
Uncharacterized Protein ◽  
Form Complex

AbstractTransposable elements are common targets for transcriptional and post-transcriptional gene silencing in eukaryotic genomes. However, the molecular mechanisms responsible for sensing such repeated sequences in the genome remain largely unknown. Here, we show that machinery of homologous recombination (HR) and RNA silencing play cooperative roles in copy number-dependent de novo DNA methylation of the retrotransposon MAGGY in the fungusPyricularia oryzae. Genetic and physical interaction studies revealed thatRecAdomain-containing proteins, includingP. oryzaehomologs ofRad51, Rad55, andRad57, together with an uncharacterized protein, Ddnm1, form complex(es) and mediate either the overall level or the copy number-dependence of de novo MAGGY DNA methylation, likely in conjunction with DNA repair. Interestingly,P. oryzaemutants of specific RNA silencing components (MoDCL1andMoAGO2)were impaired in copy number-dependence of MAGGY methylation. Co-immunoprecipitation of MoAGO2 and HR components suggested a physical interaction between the HR and RNA silencing machinery in the process.

scholarly journals The L1-dependant and Pol III transcribed Alu retrotransposon, from its discovery to innate immunity

2021 ◽  
Vol 48 (3) ◽  
pp. 2775-2789
Author(s):  
Ludwig Stenz
Keyword(s):  
Human Genome ◽  
Viral Infections ◽  
De Novo ◽  
Current Knowledge ◽  
Innate Immune ◽  
De Novo Mutation ◽  
Neuronal Diversity ◽  
Alu Sequences ◽  
Pol Iii ◽  
The Brain

AbstractThe 300 bp dimeric repeats digestible by AluI were discovered in 1979. Since then, Alu were involved in the most fundamental epigenetic mechanisms, namely reprogramming, pluripotency, imprinting and mosaicism. These Alu encode a family of retrotransposons transcribed by the RNA Pol III machinery, notably when the cytosines that constitute their sequences are de-methylated. Then, Alu hijack the functions of ORF2 encoded by another transposons named L1 during reverse transcription and integration into new sites. That mechanism functions as a complex genetic parasite able to copy-paste Alu sequences. Doing that, Alu have modified even the size of the human genome, as well as of other primate genomes, during 65 million years of co-evolution. Actually, one germline retro-transposition still occurs each 20 births. Thus, Alu continue to modify our human genome nowadays and were implicated in de novo mutation causing diseases including deletions, duplications and rearrangements. Most recently, retrotransposons were found to trigger neuronal diversity by inducing mosaicism in the brain. Finally, boosted during viral infections, Alu clearly interact with the innate immune system. The purpose of that review is to give a condensed overview of all these major findings that concern the fascinating physiology of Alu from their discovery up to the current knowledge.

scholarly journals The Prion-Like Spreading of Alpha-Synuclein in Parkinson’s Disease: Update on Models and Hypotheses

2021 ◽  
Vol 22 (15) ◽  
pp. 8338
Author(s):  
Asad Jan ◽  
Nádia Pereira Gonçalves ◽  
Christian Bjerggaard Vaegter ◽  
Poul Henning Jensen ◽  
Nelson Ferreira
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Molecular Mechanisms ◽  
De Novo ◽  
Alpha Synuclein ◽  
Experimental Models ◽  
Cellular Factors ◽  
Recent Developments ◽  
Novel Targets ◽  
Presynaptic Protein

The pathological aggregation of the presynaptic protein α-synuclein (α-syn) and propagation through synaptically coupled neuroanatomical tracts is increasingly thought to underlie the pathophysiological progression of Parkinson’s disease (PD) and related synucleinopathies. Although the precise molecular mechanisms responsible for the spreading of pathological α-syn accumulation in the CNS are not fully understood, growing evidence suggests that de novo α-syn misfolding and/or neuronal internalization of aggregated α-syn facilitates conformational templating of endogenous α-syn monomers in a mechanism reminiscent of prions. A refined understanding of the biochemical and cellular factors mediating the pathological neuron-to-neuron propagation of misfolded α-syn will potentially elucidate the etiology of PD and unravel novel targets for therapeutic intervention. Here, we discuss recent developments on the hypothesis regarding trans-synaptic propagation of α-syn pathology in the context of neuronal vulnerability and highlight the potential utility of novel experimental models of synucleinopathies.

De Novo Autoimmune Hepatitis

2021 ◽  
pp. 360-363
Author(s):  
James Neuberger
Keyword(s):  
Autoimmune Hepatitis ◽  
De Novo
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