title: Microbial and immunological responses relative to high-altitude exposure in mountaineers.
abstract: OBJECTIVE
  High-altitude exposure is often associated with gastrointestinal disorders, inflammation, and an increased risk of infection. We suspected microbial and immunological responses to high-altitude exposure in mountaineers resulting from changes in the balance of the intestinal microflora.
  
  
  METHODS
  We investigated fecal samples and serum of seven mountaineers who took part in a 47-d German expedition to the Nepalese Himalayas in 2002, for microbial response by changes in different fecal bacterial population groups (fluorescent in situ hybridization), immune response by serum levels of IgG-, IgM-, and IgA anti-LPS (E. coli J5), and inflammatory response by serum levels of C-reactive protein (CRP) (ELISA). In addition, measurements of body temperature, pulse rate, arterial oxygen saturation, and questionnaire (Lake Louise score for altitude illness) were performed.
  
  
  RESULTS
  The data indicate a distinct alteration in the composition of the fecal microflora relative to high-altitude exposure above 5000 m. Bifidobacteria and species belonging to the Atopobium, Coriobacterium, and Eggerthella lenta group decreased, whereas potential pathogenic bacteria of the gamma subdivision of Proteobacteria and specific Enterobacteriaceae such as Escherichia coli increased. Possible endotoxemia resulting from the increase of the latter Gram-negative bacteria was indirectly indicated by the reduction in serum levels of IgM- and/or IgA anti-LPS. CRP was elevated relative to high-altitude exposure. The Lake Louise score correlated with the changes in CRP, IgA-, and IgM anti-LPS but did not correlate with the bacterial alterations.
  
  
  CONCLUSIONS
  Changes in the composition of intestinal microbiota may be associated with indicators of an immunological challenge and may result in an increased health risk of mountaineers during exposure to very high altitude.
authors.affiliation: Institute of Bacteriology and Mycology, University of Leipzig, Leipzig, Germany. b.kleessen@gmx.de
authors.forename: Brigitta
authors.initials: B
authors.lastname: Kleessen
authors.forename: Wieland
authors.initials: W
authors.lastname: Schroedl
authors.forename: Marcus
authors.initials: M
authors.lastname: Stueck
authors.forename: Andreas
authors.initials: A
authors.lastname: Richter
authors.forename: Olaf
authors.initials: O
authors.lastname: Rieck
authors.forename: Monika
authors.initials: M
authors.lastname: Krueger
mesh_terms: D000328:Adult; D000531:Altitude; D001419:Bacteria / Q000145:classification / Q000302:isolation & purification; D002097:C-Reactive Protein / Q000032:analysis; D004797:Enzyme-Linked Immunosorbent Assay; D005243:Feces / Q000382:microbiology*; D005260:Female; D005858:Germany; D006801:Humans; D007136:Immunoglobulins / Q000097:blood*; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D009051:Mountaineering; D011795:Surveys and Questionnaires
chemical_list: D007136:Immunoglobulins; D002097:C-Reactive Protein