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Hirschfield G.M.,University of Toronto | Invernizzi P.,Center for Autoimmune Liver Diseases
Seminars in Liver Disease | Year: 2011

Primary biliary cirrhosis (PBC) is a chronic cholestatic liver disease that has a prevalence of 1 in 1000 women over the age of 40. Treatment is presently limited to ursodeoxycholic acid, a hydrophilic bile acid that has nonspecific, choleretic, effects in cholestatic liver disease. PBC has strong autoimmune features, including highly specific loss of tolerance to a ubiquitous mitochondrial antigen. Both environmental and genetic factors are considered important in the pathogenesis of disease. Prior to the advent of genome-wide association studies, only class II human leucocyte antigen (HLA) loci (HLA-DRB1*08,*11, and*13) had been reproducibly shown to associate with disease. Non-HLA loci were suggested for several genes (e.g., CTLA-4, MDR3), but often inconclusively replicated. With the application of genome-wide technology, HLA was confirmed as the strongest association and many other risk loci have been identified, with equivalent effect size to HLA, including IL12A, IL12RB2, STAT4, IRF5-TNPO3, 17q12.21, MMEL1, SPIB, and CTLA-4. These collectively support an important role for innate and adaptive immunity in development of disease. Further insights are predicted as studies with larger cohorts are assembled, and different approaches are taken to further discover common and uncommon gene variants associated with disease. Disease subphenotypes such as response to therapy, clinical progression, and symptoms remain additional areas for further dedicated studies, and in which different genetic risk factors may be relevant. Identification of risk loci associated with disease has the potential to aid development of rational, disease-specific, therapies in the future. © 2011 by Thieme Medical Publishers, Inc.

Invernizzi P.,Center for Autoimmune Liver Diseases | Invernizzi P.,University of California at Davis
Hepatology | Year: 2011

Primary biliary cirrhosis (PBC) is an autoimmune biliary disease characterized by injury of small and medium size bile ducts, eventually leading to liver cirrhosis and death. Although the causes remain enigmatic, recent evidence has strengthened the importance of genetic factors in determining the susceptibility to the disease. Besides the strong heritability suggested by familial occurrence and monozygotic twins concordance, for decades there has not been a clear association with specific genes, with the only exception of a low risk conferred by a class II human leukocyte antigen (HLA) variant, the DRB1*08 allele, at least in some populations. The picture has become more complete when strong protective associations between PBC and the HLA DRB1*11 and DRB1*13 alleles were found in Italian and UK series. However, HLA genes have begun again to attract interest thanks to recent genome-wide association studies (GWAS), which clearly demonstrated that the major components of the genetic architecture of PBC are within the HLA region. As expected in a genetically complex disease, GWAS also identified several novel non-HLA variants, but it is worth noting that all of them are in immuno-related genes. In this review, the paradigmatic tale of what, and how, we learned about HLA genes in PBC will be retraced with particular focus on how GWAS are enabling a rewriting the story of PBC pathogenesis. These recent discoveries will not only drive functional studies but will also hold the promise of developing novel disease-specific treatments. © 2011 American Association for the Study of Liver Diseases.

Recalcati S.,University of Milan | Locati M.,University of Milan | Locati M.,Laboratory for Leukocyte Biology | Gammella E.,University of Milan | And 2 more authors.
Autoimmunity Reviews | Year: 2012

Although the hallmark of autoimmune diseases remains the generation of autoantigen-specific lynfocytic cell response, growing evidence is showing a key role for macrophages in a number of autoimmune diseases. Macrophages are characterized by phenotypical and functional heterogeneity. Different immunological signals, coming from systemic blood circulation or from microenvironment, polarize macrophages to classical (M1) or alternative (M2) phenotypes. Iron accumulation in M1 macrophages is a well known bacteriostatic mechanism and one of the mechanisms at the basis of anemia associated to chronic inflammation. Moreover, some recent data suggest that iron accumulation in macrophages can directly activate macrophages to pro-inflammatory M1 phenotype, highlighting a putative role of macrophage iron retention in the pathogenesis of chronic inflammatory and autoimmune diseases. Conversely, iron content is low in M2 macrophages, principally due to increased iron release, and increased availability of iron in the extracellular milieu supported by M2 macrophages could influence the growth rate of adjacent cell and thus play an important role in tumor growth and tissue remodeling.In this review we summarize the molecular mechanisms sustaining differential iron metabolism in polarized macrophages, discuss the relevance of this metabolic signature in chronic inflammatory and autoimmune diseases, and finally focus on potential therapeutic implications rising from a better understanding of underlying molecular mechanisms. © 2012 Elsevier B.V.

Bogdanos D.P.,Kings College London | Bogdanos D.P.,University of Thessaly | Smyk D.S.,Kings College London | Invernizzi P.,Center for Autoimmune Liver Diseases | And 4 more authors.
Autoimmunity Reviews | Year: 2013

The "exposome" is a term recently used to describe all environmental factors, both exogenous and endogenous, which we are exposed to in a lifetime. It represents an important tool in the study of autoimmunity, complementing classical immunological research tools and cutting-edge genome wide association studies (GWAS). Recently, environmental wide association studies (EWAS) investigated the effect of environment in the development of diseases. Environmental triggers are largely subdivided into infectious and non-infectious agents. In this review, we introduce the concept of the "infectome", which is the part of the exposome referring to the collection of an individual's exposures to infectious agents. The infectome directly relates to geoepidemiological, serological and molecular evidence of the co-occurrence of several infectious agents associated with autoimmune diseases that may provide hints for the triggering factors responsible for the pathogenesis of autoimmunity. We discuss the implications that the investigation of the infectome may have for the understanding of microbial/host interactions in autoimmune diseases with long, pre-clinical phases. It may also contribute to the concept of the human body as a superorganism where the microbiome is part of the whole organism, as can be seen with mitochondria which existed as microbes prior to becoming organelles in eukaryotic cells of multicellular organisms over time. A similar argument can now be made in regard to normal intestinal flora, living in symbiosis within the host. We also provide practical examples as to how we can characterise and measure the totality of a disease-specific infectome, based on the experimental approaches employed from the "immunome" and "microbiome" projects. © 2012 Elsevier B.V.

Moroni L.,Center for Autoimmune Liver Diseases | Bianchi I.,Center for Autoimmune Liver Diseases | Lleo A.,Center for Autoimmune Liver Diseases | Lleo A.,University of Milan
Autoimmunity Reviews | Year: 2012

Autoimmune diseases include more than 70 different disorders affecting over 5% of the population of the Western countries. They are mainly characterized by female predominance and have great impact on the quality of life of affected subjects. It is generally accepted that ADs are the result of a complex interaction between genetic and environmental factors; however the mechanisms involved in the loss of tolerance remain unknown. Studying the distribution of these conditions across various global regions and ethnic groups by means of geoepidemiology might readily provide epidemiological data and also advance our understanding of their pathogenesis. Indeed, geoepidemiology demonstrates that genetic susceptibility interacts with lifestyle and environmental factors, which include socioeconomic status, infectious agents (triggering or protective agents), environmental pollutants, and vitamin D (dependent on sunlight exposure), in determining the risk of developing autoimmunity and in the understanding of their female prevalence. To properly understand the geoepidemiology of human autoimmunity, it is important to consider the many pleiotropic factors which lead to its initiation. In most studies the focus has been on genetics and environment. However, in this review the focus is primarily on gender. Overall, autoimmune diseases are well known to have female predominance, but there is significant variation in geographic area. Further, the mechanisms that influence female predominance are relatively unknown. Hence the attempt in this review is to focus on these critical issues. © 2011 Elsevier B.V.

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