Human hantavirus infection elicits pronounced redistribution of mononuclear phagocytes in peripheral blood and airways

PLoS Pathog. 2017 Jun 22;13(6):e1006462. doi: 10.1371/journal.ppat.1006462. eCollection 2017 Jun.

Abstract

Hantaviruses infect humans via inhalation of virus-contaminated rodent excreta. Infection can cause severe disease with up to 40% mortality depending on the viral strain. The virus primarily targets the vascular endothelium without direct cytopathic effects. Instead, exaggerated immune responses may inadvertently contribute to disease development. Mononuclear phagocytes (MNPs), including monocytes and dendritic cells (DCs), orchestrate the adaptive immune responses. Since hantaviruses are transmitted via inhalation, studying immunological events in the airways is of importance to understand the processes leading to immunopathogenesis. Here, we studied 17 patients infected with Puumala virus that causes a mild form of hemorrhagic fever with renal syndrome (HFRS). Bronchial biopsies as well as longitudinal blood draws were obtained from the patients. During the acute stage of disease, a significant influx of MNPs expressing HLA-DR, CD11c or CD123 was detected in the patients' bronchial tissue. In parallel, absolute numbers of MNPs were dramatically reduced in peripheral blood, coinciding with viremia. Expression of CCR7 on the remaining MNPs in blood suggested migration to peripheral and/or lymphoid tissues. Numbers of MNPs in blood subsequently normalized during the convalescent phase of the disease when viral RNA was no longer detectable in plasma. Finally, we exposed blood MNPs in vitro to Puumala virus, and demonstrated an induction of CCR7 expression on MNPs. In conclusion, the present study shows a marked redistribution of blood MNPs to the airways during acute hantavirus disease, a process that may underlie the local immune activation and contribute to immunopathogenesis in hantavirus-infected patients.

MeSH terms

  • Endothelium, Vascular / virology*
  • Hantavirus Infections / immunology*
  • Hantavirus Pulmonary Syndrome / immunology
  • Hantavirus Pulmonary Syndrome / virology
  • Hemorrhagic Fever with Renal Syndrome / immunology
  • Hemorrhagic Fever with Renal Syndrome / virology*
  • Humans
  • Immunity, Humoral / immunology
  • Phagocytes / immunology
  • Phagocytes / virology*
  • RNA, Viral / genetics

Substances

  • RNA, Viral

Grants and funding

This work was supported by the following sources: the Swedish Research Council (www.vr.se; K2013-99X-22242-01-5 [ASS], 521-2013-8623 [HGL], 2015-02499 [HGL]), the Swedish Government for Innovation Systems (www.vinnova.se; P37128-1 [ASS]), the Swedish Foundation for Strategic Research (http://stratresearch.se/en/; SB12-0003 [HGL]), the Swedish Heart-Lung Foundation (www.hjart-lungfonden.se; 20140591 [ASS], 20150752 [CA]), the County Council of Västerbotten (www.vll.se; VLL-457671 [CA]), Karolinska Institutet (www.ki.se; 2-69/2014 [ASS]) and Umeå University (www.umu.se; [CA]). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.