title: Chlamydia pneumoniae and osteoporosis-associated bone loss: a new risk factor?
abstract: We found an association between the presence of Chlamydia pneumoniae DNA both in osteoporotic bone tissue and peripheral blood mononuclear cells (PBMCs) and the increase in circulating resorptive cytokines.
  
  
  BACKGROUND
  Our study was designed to determine whether C. pneumoniae infection may be involved in osteoporosis-associated bone loss.
  
  
  METHODS
  The study included 59 women undergoing hip joint replacement surgery for femoral neck fracture: 32 with osteoporosis and 27 with osteoarthritis. A total of 118 tissue specimens (59 bone tissues, 59 PBMCs) were examined for C. pneumoniae DNA by real-time polymerase chain reaction (PCR). Serum levels of soluble receptor activator of nuclear factor kappa B ligand (sRANKL), osteoprotegerin (OPG), interleukin (IL)-1β, tumor necrosis factor-α, and IL-6 were also measured.
  
  
  RESULTS
  C. pneumoniae DNA was detected in osteoporotic bone tissue whereas it was not found in non-osteoporotic bone tissue (p < 0.05). A significantly higher rate of C. pneumoniae DNA (p < 0.05) was found in PBMCs of osteoporotic patients than in those of osteoarthritis patients. Among osteoporotic patients, serum sRANKL, IL-1, and IL-6 concentrations as well as sRANKL/OPG ratio significantly differ between patients with bone tissue and PBMCs positive to C. pneumoniae and C. pneumoniae-negative patients.
  
  
  CONCLUSIONS
  The association between the presence of C. pneumoniae DNA, both in bone tissue and PBMCs, and the increase in sRANKL/OPG ratio as well as in IL-1β and IL-6 levels observed in osteoporotic patients suggests C. pneumoniae infection as a new risk factor for osteoporosis.
authors.affiliation: Department of Public Health and Infectious Diseases, "Sapienza" University, P.le Aldo Moro 5, 00185 Rome, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Di Pietro
authors.forename: G
authors.initials: G
authors.lastname: Schiavoni
authors.forename: V
authors.initials: V
authors.lastname: Sessa
authors.forename: F
authors.initials: F
authors.lastname: Pallotta
authors.forename: G
authors.initials: G
authors.lastname: Costanzo
authors.forename: R
authors.initials: R
authors.lastname: Sessa
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip; D016022:Case-Control Studies; D023521:Chlamydophila Infections / Q000097:blood / Q000150:complications*; D016993:Chlamydophila pneumoniae / Q000235:genetics / Q000302:isolation & purification*; D016207:Cytokines / Q000097:blood; D004269:DNA, Bacterial / Q000032:analysis; D005260:Female; D005265:Femoral Neck Fractures / Q000601:surgery; D005270:Femur Head / Q000382:microbiology; D006801:Humans; D018836:Inflammation Mediators / Q000097:blood; D007963:Leukocytes, Mononuclear / Q000382:microbiology; D015207:Osteoarthritis, Hip / Q000601:surgery; D015663:Osteoporosis, Postmenopausal / Q000097:blood / Q000382:microbiology*; D058866:Osteoporotic Fractures / Q000601:surgery; D012307:Risk Factors
chemical_list: D016207:Cytokines; D004269:DNA, Bacterial; D018836:Inflammation Mediators