Lytic viral replication and immunopathology in a cytomegalovirus-induced mouse model of secondary hemophagocytic lymphohistiocytosis

Virol J. 2017 Dec 19;14(1):240. doi: 10.1186/s12985-017-0908-0.

Abstract

Background: Hemophagocytic lymphohistiocytosis (HLH) is a rare immunological disorder caused by unbridled activation of T cells and macrophages, culminating in a life-threatening cytokine storm. A genetic and acquired subtype are distinguished, termed primary and secondary HLH, respectively. Clinical manifestations of both forms are frequently preceded by a viral infection, predominantly with herpesviruses. The exact role of the viral infection in the development of the hemophagocytic syndrome remains to be further elucidated.

Methods: We utilized a recently developed murine model of cytomegalovirus-associated secondary HLH and dissected the respective contributions of lytic viral replication and immunopathology in its pathogenesis.

Results: HLH-like disease only developed in cytomegalovirus-susceptible mouse strains unable to clear the virus, but the severity of symptoms was not correlated to the infectious viral titer. Lytic viral replication and sustained viremia played an essential part in the pathogenesis since abortive viral infection was insufficient to induce a full-blown HLH-like syndrome. Nonetheless, a limited set of symptoms, in particular anemia, thrombocytopenia and elevated levels of soluble CD25, appeared less dependent of the viral replication but rather mediated by the host's immune response, as corroborated by immunosuppressive treatment of infected mice with dexamethasone.

Conclusion: Both virus-mediated pathology and immunopathology cooperate in the pathogenesis of full-blown virus-associated secondary HLH and are closely entangled. A certain level of viremia appears necessary to elicit the characteristic HLH-like symptoms in the model.

Keywords: HLH; Hemophagocytic lymphohistiocytosis; MAS; MCMV; immunopathology; macrophage activation syndrome; mouse cytomegalovirus; mouse model; virus-mediated pathology.

MeSH terms

  • Animals
  • Antiviral Agents / pharmacology
  • Cidofovir
  • Cytosine / analogs & derivatives
  • Cytosine / pharmacology
  • Dexamethasone / pharmacology
  • Disease Models, Animal*
  • Humans
  • Immunosuppressive Agents / pharmacology
  • Interleukin-2 Receptor alpha Subunit / drug effects
  • Interleukin-2 Receptor alpha Subunit / immunology
  • Lymphohistiocytosis, Hemophagocytic / drug therapy
  • Lymphohistiocytosis, Hemophagocytic / immunology
  • Lymphohistiocytosis, Hemophagocytic / physiopathology*
  • Lymphohistiocytosis, Hemophagocytic / virology*
  • Mice
  • Mice, Inbred BALB C
  • Mice, Knockout
  • Muromegalovirus / physiology*
  • Organophosphonates / pharmacology
  • T-Lymphocytes / drug effects
  • T-Lymphocytes / immunology
  • Toll-Like Receptor 3 / agonists
  • Toll-Like Receptor 3 / physiology
  • Toll-Like Receptor 9 / agonists
  • Toll-Like Receptor 9 / physiology
  • Virus Diseases / physiopathology*
  • Virus Replication / drug effects
  • Virus Replication / physiology*

Substances

  • Antiviral Agents
  • Immunosuppressive Agents
  • Interleukin-2 Receptor alpha Subunit
  • Organophosphonates
  • Toll-Like Receptor 3
  • Toll-Like Receptor 9
  • Dexamethasone
  • Cytosine
  • Cidofovir