Elsevier

Journal of Infection

Volume 68, Issue 4, April 2014, Pages 387-394
Journal of Infection

Regulatory T cell response correlates with the severity of human hantavirus infection

https://doi.org/10.1016/j.jinf.2013.11.007Get rights and content

Summary

Objectives

Hantaviruses are an important group of emerging zoonotic pathogens, with significant mortality rates. Immunopathology is thought to be important in hantaviral disease, but the balance between protective and harmful responses is unknown. We studied Puumala hantavirus (PUUV) infection, which causes hemorrhagic fever with renal syndrome (HFRS) with a generally mild but highly variable clinical course.

Methods

Clinical data and blood samples were collected from 24 patients with acute PUUV infection, and analyzed by flow cytometry and quantitative PCR.

Results

The patients had a significantly increased frequency of CD4+ and CD8+ cells expressing the cell cycle marker Ki-67, but the magnitude of the effector T cell response did not correlate with disease severity. The frequency of FOXP3+ regulatory T (Treg) cells expressing Ki-67 was also increased, and likewise did not correlate with disease outcome. In contrast, the level of FOXP3 expression, a surrogate of the suppressive phenotype, had a strong positive correlation with disease severity. This correlation was also found in samples taken 6–12 months after the HFRS.

Conclusions

The best predictor of a severe disease course in HFRS was the FOXP3+ Treg cell response, suggesting that the role of Treg cells in acute human hantaviral infections may be deleterious.

Introduction

Hantaviruses are an expanding group of emerging zoonotic pathogens, responsible for two distinct syndromes.1, 2, 3 Old World viruses cause hemorrhagic fever with renal syndrome (HFRS), while American types cause hantaviral pulmonary syndrome (HPS); both can be associated with significant mortality rates. Immunopathology has been suggested to be at least partly responsible for hantaviral disease.4, 5, 6 For example, vascular endothelium is an important target of the infection, but in endothelial cell cultures the viruses are noncytopathic, implying alternative pathogenetic mechanisms. In HPS cytotoxic T cells recognizing infected endothelial cells have been reported to be critical for the development of respiratory distress,7 and Th1-derived IFN-γ has also been linked to severe HPS.8 Conversely, the immunosuppressive and Th1-antagonist cytokine TGF-β has been reported to be decreased in acute HPS and HFRS.8, 9 On the other hand, in an animal model of HPS the disease can develop independently of T cells.10 Thus, the balance between protective and harmful responses in hantaviral infections remains ill-defined.

Puumala hantavirus (PUUV) is endemic in northern Europe and causes a generally mild form of HFRS.11 The patients present with sudden fever, headache, backpain and gastrointestinal symptoms, and a large proportion also have ocular findings. Renal involvement is manifested by decreased renal function, proteinuria and hematuria. Fluid retention is observed during oliguria, which is followed by polyuric phase and recovery. Transient hypotension is present in some patients.

The clinical course of PUUV infection is highly variable, with infections ranging from subclinical seroconversion to very severe cases involving shock and anuria, requiring intensive care and dialysis.6, 12 In rare cases the infection can be fatal. Although differences in the virus strain might affect the outcome, it is more likely that host factors are important.6, 13 The disease course is linked to HLA class I alleles,14, 15 suggesting that the nature of the CD8+ T cell response may be important. Similarly to other hantaviral infections, cytotoxic T cells have been found to infiltrate the target organs.16 Patients with acute PUUV infection have increased extracellular levels of the cytotoxic molecule perforin, and the levels correlate with the amount of serum lactate dehydrogenase, a marker of cell membrane damage.17 The release of cytotoxic granules from T cells may thus be a major mechanism of cell death.

The acute phase immune response against PUUV is vigorous and both CD4+ and CD8+ T cells have been shown to participate.18, 19, 20 Virus persistence or latency has not been reported, and reinfections are not thought to occur.19 Moreover, as PUUV infects vascular endothelium,6 peripheral blood is a relevant infection focus to analyze. These features, together with the clearly delineated acute syndrome, make PUUV infection a good model to study the role of immune response in a primary human hantaviral infection and HFRS. Here, we have characterized the T cell response during acute PUUV infection, to identify components of adaptive immunity predicting the clinical outcome of the disease.

Section snippets

Patients and samples

The patients presented with acute PUUV infection, confirmed by clinically validated serological methods, at the Tampere University Hospital (Tampere, Finland) between March 2004 and October 2006. The median age was 46.5 y (range 24–74 y; 12/24 women). Control samples were taken from healthy adult volunteers. Clinical parameters were monitored daily during the hospitalization, using routine techniques in the hospital laboratory. Venous blood samples were drawn at presentation and at a control

Clinical characteristics

Twenty-four adult patients presenting with acute, serologically confirmed PUUV infection were enrolled in the study, half of them were male. The main clinical and laboratory findings during acute HFRS are summarized in Table 1.

Many clinical and laboratory parameters can be used to track the severity of the acute disease and the different components of the pathology at different stages of the infection.12 To find a marker for overall severity in our patient cohort we determined how these

Discussion

T cells have a two-sided role in viral infections. On the one hand, they are an essential component of the host defense against intracellular pathogens, and on the other they are often at least partly responsible for the organ damage and symptomatic disease caused by viruses. Both roles have been demonstrated in murine models, but data from primary human infections is scarce and conflicting.37 Hantaviruses exemplify many of the complications. Many studies have linked increased immune activity,

Acknowledgments

The authors thank Katriina Ylinikkilä, Eini Eskola and Tamás Bazsinka for technical assistance.

The study was supported by Helsinki Biomedical Graduate School, the Competitive Research Funding of the Tampere University Hospital and Helsinki University Hospital, the EC Project “Diagnosis and control of rodent-borne viral zoonoses in Europe” (QLK2-CT-2002-01358), and NIH grant number U19 AI57319. The authors report no conflicts of interest.

References (50)

  • R.M. Maizels et al.

    Regulatory T cells in infection

    Adv Immunol

    (2011)
  • C.B. Jonsson et al.

    A global perspective on hantavirus ecology, epidemiology, and disease

    Clin Microbiol Rev

    (2010)
  • W. Muranyi et al.

    Hantavirus infection

    J Am Soc Nephrol

    (2005)
  • S.F. Khaiboullina et al.

    Hantavirus immunology

    Viral Immunol

    (2002)
  • E.D. Kilpatrick et al.

    Role of specific CD8+ T cells in the severity of a fulminant zoonotic viral hemorrhagic fever, hantavirus pulmonary syndrome

    J Immunol

    (2004)
  • M. Sadeghi et al.

    Cytokine expression during early and late phase of acute Puumala hantavirus infection

    BMC Immunol

    (2011)
  • C.D. Hammerbeck et al.

    T cells are not required for pathogenesis in the Syrian hamster model of hantavirus pulmonary syndrome

    J Virol

    (2011)
  • A. Vaheri et al.

    Hantavirus infections in Europe and their impact on public health

    Rev Med Virol

    (2012)
  • M. Terajima et al.

    T cells and pathogenesis of hantavirus cardiopulmonary syndrome and hemorrhagic fever with renal syndrome

    Viruses

    (2011)
  • J. Mustonen et al.

    Association of HLA B27 with benign clinical course of nephropathia epidemica caused by Puumala hantavirus

    Scand J Immunol

    (1998)
  • J. Klingstrom et al.

    Loss of cell membrane integrity in puumala hantavirus-infected patients correlates with levels of epithelial cell apoptosis and perforin

    J Virol

    (2006)
  • T. Tuuminen et al.

    Human CD8+ T cell memory generation in Puumala hantavirus infection occurs after the acute phase and is associated with boosting of EBV-specific CD8+ memory T cells

    J Immunol

    (2007)
  • H.L. Van Epps et al.

    Long-lived memory T lymphocyte responses after hantavirus infection

    J Exp Med

    (2002)
  • T. Lindgren et al.

    Longitudinal analysis of the human T cell response during acute hantavirus infection

    J Virol

    (2011)
  • A. Plyusnina et al.

    Analysis of complete Puumala virus genome, Finland

    Emerg Infect Dis

    (2012)
  • Cited by (22)

    • Heterologous boosting of nonrelated toxoid immunity during acute Puumala hantavirus infection

      2021, Vaccine
      Citation Excerpt :

      Taken together, these findings show a difference between baseline immunity to TT and PT, but also suggest that heterologous boosting has distinct effects on the humoral responses to these two protein antigens. We have previously shown that the single best surrogate for NE severity is the length of hospitalization [18]. To determine whether the highly variable clinical course of NE affected the heterologous responses we compared the change in TT- and PT-specific IgG levels between d0 and d14, and between d14 and 1y with hospitalization length, but found no significant correlations (Supplemental Fig. S3).

    • Meeting report: Tenth International Conference on Hantaviruses

      2016, Antiviral Research
      Citation Excerpt :

      He first reviewed the pathobiology of hantavirus infections, and mentioned that endothelial cells and monocyte/macrophages are the main targets of the virus, and that vascular leakage of endothelial cells (increased capillary permeability) is a key element, mediated largely by bradykinin. He also stated that additional contributing mechanisms include thrombocytopenia, complement activation, certain cytokines (such as interleukin 6 and tumor necrosis factor -alpha), the host genotype, neutralizing antibodies and cytotoxic and regulatory T cells play a role in the pathogenesis of hantavirus diseases (Charbonnel et al., 2014; Koivula et al., 2014; Mustonen et al., 2013; Vaheri et al., 2013). Antti mentioned that the Helsinki group has recent evidence that also tissue plasminogen activator and galectin-3 binding protein (AKA Mac-2 binding protein) play a role and cited evidence suggesting that the latter may be part of the innate immunity system (Hepojoki et al., 2014; Strandin et al., 2016).

    View all citing articles on Scopus
    View full text