Francesca Virdis

@article{pmid32690655,

title = {Human Hepatitis B Viral Infection Outcomes Are Linked to Naturally Occurring Variants of HLA-DOA That Have Altered Function},

author = {A. M. Graves and F. Virdis and E. Morrison and M. Álvaro-Benito and A. A. Khan and C. Freund and T. V. Golovkina and L. K. Denzin},

year  = {2020},

date = {2020-01-01},

journal = {J Immunol},

volume = {205},

number = {4},

pages = {923--935},

abstract = {HLA molecules of the MHC class II (MHCII) bind and present pathogen-derived peptides for CD4 T cell activation. Peptide loading of MHCII in the endosomes of cells is controlled by the interplay of the nonclassical MHCII molecules, HLA-DM (DM) and HLA-DO (DO). DM catalyzes peptide loading, whereas DO, an MHCII substrate mimic, prevents DM from interacting with MHCII, resulting in an altered MHCII-peptide repertoire and increased MHCII-CLIP. Although the two genes encoding DO (DOA and DOB) are considered nonpolymorphic, there are rare natural variants. Our previous work identified DOB variants that altered DO function. In this study, we show that natural variation in the DOA gene also impacts DO function. Using the 1000 Genomes Project database, we show that ∼98% of individuals express the canonical DOA*0101 allele, and the remaining individuals mostly express DOA*0102, which we found was a gain-of-function allele. Analysis of 25 natural occurring DOα variants, which included the common alleles, identified three null variants and one variant with reduced and nine with increased ability to modulate DM activity. Unexpectedly, several of the variants produced reduced DO protein levels yet efficiently inhibited DM activity. Finally, analysis of associated single-nucleotide polymorphisms genetically linked the DOA*0102 common allele, a gain-of-function variant, with human hepatitis B viral persistence. In contrast, we found that the DOα F114L null allele was linked with viral clearance. Collectively, these studies show that natural variation occurring in the human DOA gene impacts DO function and can be linked to specific outcomes of viral infections.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{steri_overexpression_2017,

title = {Overexpression of the Cytokine BAFF and Autoimmunity Risk},

author = {Maristella Steri and Valeria Orrù and Laura M Idda and Maristella Pitzalis and Mauro Pala and Ilenia Zara and Carlo Sidore and Valeria Faà and Matteo Floris and Manila Deiana and Isadora Asunis and Eleonora Porcu and Antonella Mulas and Maria G Piras and Monia Lobina and Sandra Lai and Mara Marongiu and Valentina Serra and Michele Marongiu and Gabriella Sole and Fabio Busonero and Andrea Maschio and Roberto Cusano and Gianmauro Cuccuru and Francesca Deidda and Fausto Poddie and Gabriele Farina and Mariano Dei and Francesca Virdis and Stefania Olla and Maria A Satta and Mario Pani and Alessandro Delitala and Eleonora Cocco and Jessica Frau and Giancarlo Coghe and Lorena Lorefice and Giuseppe Fenu and Paola Ferrigno and Maria Ban and Nadia Barizzone and Maurizio Leone and Franca R Guerini and Matteo Piga and Davide Firinu and Ingrid Kockum and Izaura {Lima Bomfim} and Tomas Olsson and Lars Alfredsson and Ana Suarez and Patricia E Carreira and Maria J Castillo-Palma and Joseph H Marcus and Mauro Congia and Andrea Angius and Maurizio Melis and Antonio Gonzalez and Marta E {Alarc{ó}n Riquelme} and Berta M da Silva and Maurizio Marchini and Maria G Danieli and Stefano {Del Giacco} and Alessandro Mathieu and Antonello Pani and Stephen B Montgomery and Giulio Rosati and Jan Hillert and Stephen Sawcer and Sandra D'Alfonso and John A Todd and John Novembre and Gon{ç}alo R Abecasis and Michael B Whalen and Maria G Marrosu and Alessandra Meloni and Serena Sanna and Myriam Gorospe and David Schlessinger and Edoardo Fiorillo and Magdalena Zoledziewska and Francesco Cucca},

doi = {10.1056/NEJMoa1610528},

issn = {1533-4406},

year  = {2017},

date = {2017-01-01},

journal = {The New England Journal of Medicine},

volume = {376},

number = {17},

pages = {1615--1626},

abstract = {BACKGROUND: Genomewide association studies of autoimmune diseases have mapped hundreds of susceptibility regions in the genome. However, only for a few association signals has the causal gene been identified, and for even fewer have the causal variant and underlying mechanism been defined. Coincident associations of DNA variants affecting both the risk of autoimmune disease and quantitative immune variables provide an informative route to explore disease mechanisms and drug-targetable pathways. 

METHODS: Using case-control samples from Sardinia, Italy, we performed a genomewide association study in multiple sclerosis followed by TNFSF13B locus-specific association testing in systemic lupus erythematosus (SLE). Extensive phenotyping of quantitative immune variables, sequence-based fine mapping, cross-population and cross-phenotype analyses, and gene-expression studies were used to identify the causal variant and elucidate its mechanism of action. Signatures of positive selection were also investigated. 

RESULTS: A variant in TNFSF13B, encoding the cytokine and drug target B-cell activating factor (BAFF), was associated with multiple sclerosis as well as SLE. The disease-risk allele was also associated with up-regulated humoral immunity through increased levels of soluble BAFF, B lymphocytes, and immunoglobulins. The causal variant was identified: an insertion-deletion variant, GCTGT→A (in which A is the risk allele), yielded a shorter transcript that escaped microRNA inhibition and increased production of soluble BAFF, which in turn up-regulated humoral immunity. Population genetic signatures indicated that this autoimmunity variant has been evolutionarily advantageous, most likely by augmenting resistance to malaria. 

CONCLUSIONS: A TNFSF13B variant was associated with multiple sclerosis and SLE, and its effects were clarified at the population, cellular, and molecular levels. (Funded by the Italian Foundation for Multiple Sclerosis and others.).},

note = {See Editorials, Korn T, Oukka M. A BAFFling Association between Malaria Resistance and the Risk of Multiple Sclerosis. N Engl J Med. 2017 Apr 27;376(17):1680-1681. doi: 10.1056/NEJMe1700720.; Stohl W., Systemic lupus erythematosus: BAFF emerges from the genetic shadows. Nat Rev Rheumatol. 2017 Jun 15. doi: 10.1038/nrrheum.2017.99; Comabella M. Neuroimmunology: B cells and variant BAFF in autoimmune disease. Nat Rev Neurol. 2017 Jun 16. doi: 10.1038/nrneurol.2017.87.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid28813660,

title = {Neutralizing Antibody Responses to Viral Infections Are Linked to the Non-classical MHC Class II Gene H2-Ob},

author = { L. K. Denzin and A. A. Khan and F. Virdis and J. Wilks and M. Kane and H. A. Beilinson and S. Dikiy and L. K. Case and D. Roopenian and M. Witkowski and A. V. Chervonsky and T. V. Golovkina},

year  = {2017},

date = {2017-01-01},

journal = {Immunity},

volume = {47},

number = {2},

pages = {310--322},

abstract = {Select humans and animals control persistent viral infections via adaptive immune responses that include production of neutralizing antibodies. The precise genetic basis for the control remains enigmatic. Here, we report positional cloning of the gene responsible for production of retrovirus-neutralizing antibodies in mice of the I/LnJ strain. It encodes the beta subunit of the non-classical major histocompatibility complex class II (MHC-II)-like molecule H2-O, a negative regulator of antigen presentation. The recessive and functionally null I/LnJ H2-Ob allele supported the production of virus-neutralizing antibodies independently of the classical MHC haplotype. Subsequent bioinformatics and functional analyses of the human H2-Ob homolog, HLA-DOB, revealed both loss- and gain-of-function alleles, which could affect the ability of their carriers to control infections with human hepatitis B (HBV) and C (HCV) viruses. Thus, understanding of the previously unappreciated role of H2-O (HLA-DO) in immunity to infections may suggest new approaches in achieving neutralizing immunity to viruses.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{orru_genetic_2013,

title = {Genetic variants regulating immune cell levels in health and disease.},

author = {Valeria Orrù and Maristella Steri and Gabriella Sole and Carlo Sidore and Francesca Virdis and Mariano Dei and Sandra Lai and Magdalena Zoledziewska and Fabio Busonero and Antonella Mulas and Matteo Floris and Wieslawa I Mentzen and Silvana A M Urru and Stefania Olla and Michele Marongiu and Maria G Piras and Monia Lobina and Andrea Maschio and Maristella Pitzalis and Maria F Urru and Marco Marcelli and Roberto Cusano and Francesca Deidda and Valentina Serra and Manuela Oppo and Rosella Pilu and Frederic Reinier and Riccardo Berutti and Luca Pireddu and Ilenia Zara and Eleonora Porcu and Alan Kwong and Christine Brennan and Brendan Tarrier and Robert Lyons and Hyun M Kang and Sergio Uzzau and Rossano Atzeni and Maria Valentini and Davide Firinu and Lidia Leoni and Gianluca Rotta and Silvia Naitza and Andrea Angius and Mauro Congia and Michael B Whalen and Chris M Jones and David Schlessinger and Gon{ç}alo R Abecasis and Edoardo Fiorillo and Serena Sanna and Francesco Cucca},

doi = {10.1016/j.cell.2013.08.041},

issn = {1097-4172},

year  = {2013},

date = {2013-09-01},

journal = {Cell},

volume = {155},

number = {1},

pages = {242--56},

abstract = {The complex network of specialized cells and molecules in the immune system has evolved to defend against pathogens, but inadvertent immune system attacks on "self" result in autoimmune disease. Both genetic regulation of immune cell levels and their relationships with autoimmunity are largely undetermined. Here, we report genetic contributions to quantitative levels of 95 cell types encompassing 272 immune traits, in a cohort of 1,629 individuals from four clustered Sardinian villages. We first estimated trait heritability, showing that it can be substantial, accounting for up to 87% of the variance (mean 41%). Next, by assessing ∼8.2 million variants that we identified and confirmed in an extended set of 2,870 individuals, 23 independent variants at 13 loci associated with at least one trait. Notably, variants at three loci (HLA, IL2RA, and SH2B3/ATXN2) overlap with known autoimmune disease associations. These results connect specific cellular phenotypes to specific genetic variants, helping to explicate their involvement in disease.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}