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The role of human lung fibroblasts in immunopathogenesis of hantaviral infections

Hantaviruses are RNA viruses that belong to the family Bunyaviridae and represent an emerging threat to human health. Depending of the virus strain involved, in humans hantaviruses cause two diseases, hemorrhagic fever with renal syndrome (HFRS) and hantavirus pulmonary syndrome (HPS). Lung disorders like pulmonary edema and pleural effusions dominate in HPS, but the underlying immune mechanisms are largely unknown. However, mild to moderate pulmonary disorders were found in HFRS patients, mostly in those infected with Puumala virus. The main transmission route from small rodents, reservoirs of hantaviruses, to humans is via the respiratory tract. Different lung compartments may have primary roles in the immunoreactivity to hantaviruses. There is some evidence suggesting a role for human lung endothelial cells and macrophages, especially in the production of different cytokines and chemokines and the expression of adhesion molecules. However, there is little information available concerning the role of human lung fibroblasts in HFRS or HPS immunopathogenesis. In addition to their connective function, lung fibroblasts are also important participants in the orchestration of acute and chronic inflammation. It is possible that lung fibroblasts produce inflammatory cytokines that are involved in cell recruitment from the vascular compartment to the lung interstitium during hantaviral infection. Nuclear factor-kB (NF-kB) has an important role in the early response to pathogens and it is activated in response to a variety of stimuli like viral infection and proinflammatory cytokines. This pathway is involved in the regulation of transcription of a great number of genes important for cell proliferation, cell survival and promoting inflammation. The aim of this study was to investigate the early activation mechanisms in human lung fibroblasts after their infection with HFRS or HPS hantaviruses. For that purpose, we used Focused Gene Expression cDNA Array Analysis (GEArrays, SuperArray Bioscience, Frederick, MD, USA) to compare expression profiles of genes in RNA samples from MRC-5 cells (human lung fibroblasts) six hours after infection with Hantaan virus or Andes virus. Three different GEArrayTM were used: GEArray Q series Human Common Cytokine Gene Array, GEArray Q series Human NFkB signaling Pathway Gene Array and GEArray Q series Human Extracellular Matrix & Adhesion Molecules Genes Array. Selected genes identified by GEArray analysis will be also analyzed by quantitative real-time PCR to verify transcriptional responses. Hantaan virus increased expression only of interleukin-6. Both viruses decreased gene-expression of bone morphogenetic protein 2 (BMP-2), while Andes virus also influenced the gene expression of some growth factors. Both viruses increased gene expression for the members of Rel/NFkB/IkB family (nuclear factor related to kappa B binding protein-NFRKB) ; NFkB responsive genes (E-selectin), transcription factors (early growth response 1-EGR-1) and adaptor proteins (TNF receptor-associated factor-TRAF-1), while Hantaan virus decreased activating transcription factor 2 (ATF-2). The changes in expression of different adhesion molecules, including  3 integrins (receptors for hantaviruses) were also detected. Further investigation is necessary to determine whether some of our observations during the early stage of lung fibroblasts infection with hantaviruses are relvant to pulmonary disorders caused by HFRS- and especially HPS-causing viruses.

hantaviruses; lung fibroblasts; gene expression

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