Enterovirus infections in type 1 diabetes and cystic fibrosis : antiviral defence and viral immune evasion strategies

Enteroviruses are common viruses which cause infections in humans that usually result in mild flu-like symptoms before viral clearance. However, in some cases these infections can progress to more severe diseases such as myocarditis, pancreatitis and hepatitis. Coxsackievirus induced hepatitis in infants may become so severe that the outcome is fatal. In addition, infections with enteroviruses belonging to the group B Coxsackieviruses have been implicated in the etiology of type 1 diabetes. Enterovirus infections are also commonly observed in patients with cystic fibrosis, resulting in lung exacerbations and morbidity. Proper antiviral response mechanisms are crucial for the prevention of viral replication and spread, as well as the inhibition of virus induced cellular damage. Recently a novel group of interferons, called type III interferons, were discovered and shown to have antiviral properties predominantly in cells of epithelial origin. In Paper I we show that type III interferons protect primary human hepatocytes from Coxsackievirus infection. Given the importance of interferons in preventing early viral replication, many viruses have developed mechanisms to inhibit their induction. In Paper II, we showed that Coxsackieviruses inhibit the induction of type III interferons in infected cells. In addition, we demonstrated that this inhibition was caused by the proteolytic activity of the viral protease 2A. The exact role of enterovirus infections in type 1 diabetes development is still under speculation. Coxsackieviruses encodes several viral proteins that have been shown to interfere with cellular function and signaling pathways. In Paper III, we used primary human pancreatic islets and an insulin-secreting cell line to identify mechanisms by which Coxsackeiviruses can cause beta cell dysfunction. We found that the viral proteins 2A, 3A and 3C could, independently of one other, affect exocytosis with 2A and 3C targeting calcium influx while 3A inhibited exocytosis via a calcium independent mechanism. An impaired antimicrobial defense has been observed in patients with cystic fibrosis. This could explain why common respiratory infections are often prolonged and more severe in these patients. By using a mouse model for cystic fibrosis, we showed in Paper IV that the most common mutation resulting in cystic fibrosis, F508del, caused an impaired adaptive immune response with a delayed production of neutralizing antibodies to Coxsackievirus. In conclusion, the studies performed in this thesis add to our understanding of innate and adaptive immune response mechanisms during Coxackievirus infections. In addition they demonstrate a role for viral proteins in circumventing host antiviral immune responses, thus causing cellular damage, which could contribute to disease pathology. Increasing the knowledge of host-pathogen interactions may help to develop new treatments that could prevent severe Coxsackievirus infections. LIST OF PUBLICATIONS I. Katharina Lind, Emma Svedin, Renata Utorova, Virginia M Stone, and Malin FlodströmTullberg. Type III Interferons are Expressed by Coxsackievirus Infected Human Primary Hepatocytes and Regulate Hepatocyte Permissiveness to Infection. Clinical and Experimental Immunology. 2014, 177:687-695 II. Katharina Lind, Emma Svedin, Erna Domsgen, Sebastian Kapell, Olli Laitinen, Markus Moll, and Malin Flodström-Tullberg. Coxsackievirus counters the host innate immune response by blocking type III interferon expression. The Journal of General Virology. 2016 vol. 97 (6) pp. 1-12 III. Emma Svedin, Erna Domsgen, Sebastian Kapell, Anna Edlund, Lena Eliasson, Malin Flodström-Tullberg. Coxsackievirus affects multiple steps in the insulin secretion pathway leading to impaired insulin release by infected beta cells. Manuscript IV. Emma Svedin, Renata Utorova, Michael H. Hühn, Pär Larsson, Manasa Gamriella, Katharina Lind, Terezia Pincikova, Gerald M. McInerney, Bob Scholte, Lena Hjelte, Mikael C. I. Karlsson, Malin Flodström-Tullberg. Enterovirus challenge reveals an association between a common polymorphism in CFTR and impaired adaptive antiviral defense. Manuscript PUBLICATIONS NOT INCLUDED IN THE THESIS SI. Olli H. Laitinen, Emma Svedin*, Sebastian Kapell*, Anssi Nurminen*, Vesa P. Hytönen and Malin Flodström-Tullberg. Enteroviral proteases: structure, host interactions and pathogenicity. Reviews in Medical Virology. 2016; 26: 251-267 * Contributed equally SII. Terezia Pincikova, Emma Svedin, Erna Domsgen, Malin Flodström-Tullberg, and Lena Hjelte. Cystic fibrosis bronchial epithelial cells have impaired ability to activate Vitamin D. Acta Paediatrica. 2016, 105, pp, 851-853 SIII. Morten Gram Pedersen, Vishal Ashok Salunkhe, Emma Svedin, Anna Edlund, and Lena Eliasson. Calcium Current Inactivation Rather than Pool Depletion Explains Reduced Exocytotic Rate with Prolonged Stimulation in Insulin-Secreting INS-1 832/13 Cells. PloS one. 2014, vol. 9 (8) p. e103874 SIV. The nPOD-V Consortium, Sarah J Richardson, Pia Leete, Shalinee Dhayal, Mark A Russell, Maarit Oikarinen, Jutta E Laiho, Emma Svedin, Katharina Lind, Therese Rosenling, Nora Chapman, Adrian J Bone, Alan K Foulis, Gun Frisk, Malin FlodströmTullberg, Didier Hober, Heikki Hyöty, and Noel G Morgan. Evaluation of the fidelity of immunolabelling obtained with clone 5D8/1, a monoclonal antibody directed against the enteroviral capsid protein, VP1, in human pancreas. Diabetologia. 2013 vol. 57 (2) pp. 392-401 SV. Pär G Larsson, Tadepally Lakshmikanth, Emma Svedin, Cecile King, and Malin Flodström-Tullberg. Previous maternal infection protects offspring from enterovirus infection and prevents experimental diabetes development in mice. Diabetologia. 2013 vol. 56 (4) pp. 867-874 SVI. Michael H Hühn, Stephen A McCartney, Katharina Lind, Emma Svedin, Marco Colonna, and Malin Flodström-Tullberg. Melanoma differentiation-associated protein-5 (MDA-5) limits early viral replication but is not essential for the induction of type 1 interferons after Coxsackievirus infection. Virology. 2010 vol. 401 (1) pp. 42-48