title: Calcitriol [1, 25[OH]2 D3] pre- and post-treatment suppresses inflammatory response to influenza A (H1N1) infection in human lung A549 epithelial cells.
abstract: OBJECTIVE
  Influenza viruses infect airway epithelial cells, causing respiratory distress. Immune defense is maintained by chemokine/cytokine secretions from airway epithelial cells. While moderate inflammatory response protects from ill effects, hyper-inflammatory response promotes the pathogenesis. High circulating levels of vitamin D are known to mitigate effects of infectious diseases, including respiratory infectious diseases. The question whether and how vitamin D treatment pre-/post-viral exposure modulates inflammatory response is not clear. The present study was undertaken to understand autophagy/apoptosis balance and chemokine/cytokine response to influenza A (H1N1) infection by pre- and post-1, 25-dihydroxyvitamin D3 (1,25[OH]2 D3)[calcitriol] treatment of human lung A549 epithelial cells.
  
  
  METHODS
  Influenza A (H1N1) virus was propagated in A549 cell line, titrated using hemagglutination assay, and was used to assess effect of calcitriol. After confirming that 100 nM of calcitriol fails to clear virus, A549 cells were either pre-treated (16 h) with 100 nM or post-treated with 30 nM of 1,25[OH]2 D3 of virus inoculation (1 h). Cells after incubation at 37 °C under 5 % CO2 for 48 h were collected and subjected to RNA and protein extraction. Measurements of viability, influenza M protein, and molecular parameters of cell death and inflammatory response were performed.
  
  
  RESULTS
  We report that treatment of these cells with 100/30 nM of 1,25[OH]2 D3 prior to/or post-H1N1 exposure does not affect viral clearance but significantly reduces autophagy and restores increased apoptosis seen on H1N1 infection back to its constitutive level. However, it significantly decreases the levels of H1N1-induced TNF-α (tumor necrosis factor-alpha), IFN-β (interferon-beta), and IFN-stimulated gene-15 (ISG15). 1,25[OH]2 D3 treatment prior to/or post-H1N1 infection significantly down-regulates IL-8 as well as IL-6 RNA levels. These results demonstrate that calcitriol treatment suppresses the H1N1-induced transcription of the chemokines RANTES and IL-8 in epithelial cells.
  
  
  CONCLUSIONS
  The findings provide support for the initiation of vitamin D supplementation program to VDD populations in reducing the severity of influenza.
authors.affiliation: Department of Endocrinology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India.
authors.forename: Drirh
authors.initials: D
authors.lastname: Khare
authors.forename: Nachiket M
authors.initials: NM
authors.lastname: Godbole
authors.forename: Shailesh D
authors.initials: SD
authors.lastname: Pawar
authors.forename: Vishwa
authors.initials: V
authors.lastname: Mohan
authors.forename: Gaurav
authors.initials: G
authors.lastname: Pandey
authors.forename: Sushil
authors.initials: S
authors.lastname: Gupta
authors.forename: Deepak
authors.initials: D
authors.lastname: Kumar
authors.forename: Tapan N
authors.initials: TN
authors.lastname: Dhole
authors.forename: Madan M
authors.initials: MM
authors.lastname: Godbole
mesh_terms: D056809:Alveolar Epithelial Cells / Q000166:cytology / Q000276:immunology / Q000378:metabolism* / Q000821:virology; D017209:Apoptosis; D001343:Autophagy; D015153:Blotting, Western; D002117:Calcitriol / Q000378:metabolism*; D002460:Cell Line; D002470:Cell Survival; D018925:Chemokines / Q000235:genetics / Q000378:metabolism; D017077:Culture Media, Conditioned / Q000737:chemistry; D016207:Cytokines / Q000235:genetics / Q000378:metabolism; D015536:Down-Regulation; D006386:Hemagglutination Tests; D006801:Humans; D007155:Immunologic Factors / Q000378:metabolism*; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology* / Q000378:metabolism; D007700:Kinetics; D012333:RNA, Messenger / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014763:Viral Matrix Proteins / Q000378:metabolism
chemical_list: D018925:Chemokines; D017077:Culture Media, Conditioned; D016207:Cytokines; D007155:Immunologic Factors; C031540:M-protein, influenza virus; D012333:RNA, Messenger; D014763:Viral Matrix Proteins; D002117:Calcitriol