Autoimmune disease: A role for new anti-viral therapies?

Autoimmunity in 2011

The mechanisms leading to the onset and perpetuation of systemic and tissue-specific autoimmune diseases are complex, and numerous hypotheses have been proposed or confirmed over the past 12 months. It is particularly of note that the number of articles published during 2011 in the major immunology and autoimmunity journals increased by 3 % compared to the previous year. The present article is dedicated to a brief review of the reported data and, albeit not comprehensive of all articles, is aimed at identifying common and future themes. First, clinical researchers were particularly dedicated to defining refractory forms of diseases and to discuss the use and switch of therapeutic monoclonal antibodies in everyday practice. Second, following the plethora of genome-wide association studies reported in most multifactorial diseases, it became clear that genomics cannot fully explain the individual susceptibility and additional environmental or epigenetic factors are necessary. Both these components were widely investigated, both in organ-specific (i.e., type 1 diabetes) and systemic (i.e., systemic lupus erythematosus) diseases. Third, a large number of 2011 works published in the autoimmunity area are dedicated to dissect pathogenetic mechanisms of tolerance breakdown in general or in specific conditions. While our understanding of T regulatory and Th17 cells has significantly increased in 2011, it is of note that most of the proposed lines of evidence identify potential targets for future treatments and should not be overlooked.

Common variable immunodeficiency: crossroads between infections, inflammation and autoimmunity

Common variable immunodeficiency is a collection of diseases characterized by primary hypogammaglobulinemia. The causes of CVID are extremely heterogeneous and may affect virtually every pathway linked to B cell development and function. Clinical manifestations of CVID mainly include recurrent bacterial infections, but autoimmune, gastrointestinal, lymphoproliferative, granulomatous, and malignant disorders have also been frequently reported as associated conditions. We aimed to focus on the state of the art of the relationship between infections, inflammation and autoimmunity in CVID.

Resolution of autoimmune thrombocytopenia associated with raltegravir use in an HIV-positive patient

About 10% of the human immunodeficiency virus (HIV) patients show thrombocytopenia. We describe the case of an HIV/HCV-positive patient whose autoimmune thrombocytopenia resolved with the addition of raltegravir to previous highly active antiretroviral therapy (HAART). It is noteworthy that the effect on platelet count appeared to be independent of viral load suppression, which was achieved with previous antiretroviral regimens. In fact, it has been suggested that the positive effect exerted by raltegravir on autoimmune diseases is due to its inhibition on herpes viruses, and hence on activation of endogenous human retroviruses. This consideration, if confirmed, could open new avenues in the treatment of autoimmune thrombocytopenia in the HIV setting.

EBV stimulates TLR- and autophagy-dependent pathways and impairs maturation in plasmacytoid dendritic cells: implications for viral immune escape

Plasmacytoid DCs (pDCs) are crucial mediators in the establishment of immunity against most viruses, given their extraordinary capacity to produce a massive quantity of type I IFN. In this study we investigate the response of pDCs to infection with EBV, a γ-herpes virus that persists with an asymptomatic infection in immunocompetent hosts, although in certain conditions it can promote development of cancers or autoimmune diseases. We show that high amounts of type I IFNs were released from isolated pDCs after exposure to EBV by a mechanism requiring TLRs and a functional autophagic machinery. We next demonstrate that EBV can infect pDCs via viral binding to MHC class II molecule HLA-DR and that pDCs express EBV-induced latency genes. Furthermore, we observe that EBV is able to induce activation but not maturation of pDCs, which correlates with an impaired TNF-α release. Accordingly, EBV-infected pDCs are unable to mount a full T-cell response, suggesting that impaired pDC maturation, combined with a concomitant EBV-mediated upregulation of the T-cell inhibitory molecules B7-H1 and ICOS-L, could represent an immune-evasion strategy promoted by the virus. These mechanisms might lead to persistence in immunocompetent hosts or to dysregulated immune responses linked to EBV-associated diseases.

Interferons as biomarkers and effectors: lessons learned from animal models

Interferons (IFNs) comprise type I, II and III families with multiple subtypes. Via transcription of IFN-stimulated genes (ISGs), IFNs can exert multiple biological effects on the cell. In infectious and chronic inflammatory diseases, the IFNs and their ISG sets can be potentially utilized as biomarkers of disease outcome. Animal models allow investigations into disease pathogenesis and gene knockout models have proved cause and effect relationships of molecules related to the IFN response. Sets of IFN subtypes and their ISG products provide immunological signature patterns for different viral and other diseases. In this article, we give an overview of IFNs in several virus infection models and autoimmune diseases of medical relevance. Lessons learned from animal models inform us of IFN system parameters as indicators of disease outcome and whether clinical research is warranted. Moreover, validated IFN biomarkers for prognosis enhance our understanding of therapeutic and vaccine development.

Immunomodulatory effects of antimicrobial agents. Part I: antibacterial and antiviral agents

Despite impressive therapeutic progresses in the battle against infections, microorganisms are still a threat to mankind. With hundreds of antibacterial molecules, major concerns remain about the emergence of resistant and multidrug-resistant pathogens. On the other hand, the antiviral drug armamentarium is comprised of only a few dozens of compounds which are highly pathogen specific, and resistance is also a concern. According to Arturo Casadevall (Albert Einstein College of Medicine, NY, USA), we have now entered the third era of anti-infective strategy, which intends to favor the interplay between active molecules and the immune system. The first part of this review focuses on the potential immunomodulating properties of anti-infective agents, beginning with antibacterial and antiviral agents.

CD8+ T-Cell Deficiency, Epstein-Barr Virus Infection, Vitamin D Deficiency, and Steps to Autoimmunity: A Unifying Hypothesis

CD8+ T-cell deficiency is a feature of many chronic autoimmune diseases, including multiple sclerosis, rheumatoid arthritis, systemic lupus erythematosus, Sjögren's syndrome, systemic sclerosis, dermatomyositis, primary biliary cirrhosis, primary sclerosing cholangitis, ulcerative colitis, Crohn's disease, psoriasis, vitiligo, bullous pemphigoid, alopecia areata, idiopathic dilated cardiomyopathy, type 1 diabetes mellitus, Graves' disease, Hashimoto's thyroiditis, myasthenia gravis, IgA nephropathy, membranous nephropathy, and pernicious anaemia. It also occurs in healthy blood relatives of patients with autoimmune diseases, suggesting it is genetically determined. Here it is proposed that this CD8+ T-cell deficiency underlies the development of chronic autoimmune diseases by impairing CD8+ T-cell control of Epstein-Barr virus (EBV) infection, with the result that EBV-infected autoreactive B cells accumulate in the target organ where they produce pathogenic autoantibodies and provide costimulatory survival signals to autoreactive T cells which would otherwise die in the target organ by activation-induced apoptosis. Autoimmunity is postulated to evolve in the following steps: (1) CD8+ T-cell deficiency, (2) primary EBV infection, (3) decreased CD8+ T-cell control of EBV, (4) increased EBV load and increased anti-EBV antibodies, (5) EBV infection in the target organ, (6) clonal expansion of EBV-infected autoreactive B cells in the target organ, (7) infiltration of autoreactive T cells into the target organ, and (8) development of ectopic lymphoid follicles in the target organ. It is also proposed that deprivation of sunlight and vitamin D at higher latitudes facilitates the development of autoimmune diseases by aggravating the CD8+ T-cell deficiency and thereby further impairing control of EBV. The hypothesis makes predictions which can be tested, including the prevention and successful treatment of chronic autoimmune diseases by controlling EBV infection.