C 2005) Digestive Diseases and Sciences, Vol. 50, No. 5 (May 2005), pp. 847–852 ( DOI: 10.1007/s10620-005-2651-4
Prevalence of Helicobacter pylori Infection in Male Patients with Osteoporosis and Controls N. FIGURA, MD, PhD,* L. GENNARI, MD,* D. MERLOTTI, MD,* C. LENZI, MD,* S. CAMPAGNA, PhD,* B. FRANCI, PhD,* B. LUCANI, PhD,* L. TRABALZINI, PhD,† L. BIANCIARDI, MD, PhD,‡ C. GONNELLI, A. SANTUCCI, PhD,† and A. NUT, MD, PhD
Cytokines that regulate bone turnover (tumor necrosis factor-α, interleukin-6, etc.) may influence the pathogenesis of skeleton disorders, such as osteoporosis. Since Helicobacter pylori infection increases the systemic levels of inflammatory cytokines, we investigated the possibility that this infection increases the risk of developing osteoporosis and affects the bone metabolism in a group of male patients with osteoporosis. We examined 80 osteoporotic male patients and 160 controls for serum antibodies to H. pylori and the CagA protein and determined, in patients alone, the most important biochemical and instrumental parameters of the disease. Fifty-one patients (63.7%) and 107 controls (66.8%) were seropositive for H. pylori infection (nonsignificant); 30 infected patients (58.8%) and 43 infected controls (40.1%) were positive for anti-CagA antibodies (P = 0.028; OR = 2.13). Levels of estradiol in infected CagA-positive patients were significantly lower than in infected CagA-negative patients (28.5 [SD = 10.18] vs. 39.5 [SD = 14.50] pg/ml; P = 0.002) and uninfected patients (35.2 [SD = 12.7] pg/ml; P = 0.028). Levels of urinary cross-laps(a marker of bone resorption) were increased in patients infected by CagA-positive strains compared to patients infected by CagA-negative strains (282.9 [SD = 103.8] vs. 210.5 [SD = 150.1] µg/mmol; P = 0.048) and uninfected patients (204.3 [SD = 130.1] µg/mmol; P = 0.016). Differences among uninfected and infected patients, independent of CagA status, were observed for other markers of bone turnover, but they did not reach statistical significance. Infection by CagA-positive H. pylori strains is more prevalent in men with osteoporosis, who show reduced systemic levels of estrogens and increased bone turnover. H. pylori infection by strains expressing CagA may therefore be considered a risk factor for osteoporisis in men. KEY WORDS: Helicobacter pylori; CagA protein; osteoporosis; estrogens; bone turnover; cytokines.
INTRODUCTION Osteoporosis is a silent, progressive disease characterized by decreased bone density and increased bone fragility, with a consequent susceptibility to fracture. Manuscript received September 4, 2003; accepted January 20, 2004. From the *Department of Internal Medicine, Endocrine-Metabolic Sciences and Biochemistry, †Department of Molecular Biology, and ‡Centro Interdipartimentale per il Recupero e la Diffusione dell’Informazione Biomedica, University of Siena, Siena, Italy. Address for reprint requests: Natale Figura, MD, PhD, Department of Internal Medicine, Endocrine-Metabolic Sciences and Biochemistry, University of Siena, Policlinico Le Scotte, viale Bracci, I-53100 Siena, Italy;
[email protected].
Women are at the greatest risk: one-third of Caucasian women over 50 have osteoporosis; osteoporosis is an emerging problem in men, too, as each year, men suffer one-third of all the hip fractures that occur (1, 2). Estrogens play an important role in modulating bone turnover, as in postmenopausal women the loss of estrogens is associated with the elaboration of cytokines, such as interleukin 1 (IL-1), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) (1). TNF-α is a potent inducer of bone resorption and IL-6 increases recruitment of osteoclast precursor cells and their differentiation into osteoclasts and also decreases osteoblast development and function (1). This series of events may lead to a net
Digestive Diseases and Sciences, Vol. 50, No. 5 (May 2005) C 2005 Springer Science+Business Media, Inc. 0163-2116/05/0500-0847/0
847
FIGURA ET AL.
loss of bone. Recent studies have suggested that female hormones may also play a role in bone remodeling in men (2). Infection by Helicobacter pylori causes chronic gastritis and induces a permanent inflammatory response that may increase both the gastric and the systemic indexes of inflammation, such as TNF-α, IL-1, and IL-6 (3–5). Strains that possess the chromosomal insertion called cag are endowed with an increased inflammatory potential, which may determine a further augmentation of local and systemic levels of cytokines (3–5). Infection by cag-bearing strains affects a variable proportion of both dyspeptic and asymptomatic individuals and can be easily diagnosed, as cag-positive clones secrete a highly immunogenic protein called CagA, which stimulates a strong antibody response (3). Since TNF-α and IL-6 are also involved in the regulation of bone turnover, we investigated the possibility that overall H. pylori and CagA-positive H. pylori infection may increase the risk of developing osteoporosis and may affect, in a group of male patients with overt disease, the parameters of bone metabolism. In order to avoid the possible influence on bone organization and integrity of the postmenopausal reduced levels of estrogens, we studied male osteoporotic patients. The results of this study were presented in part at the VIII National Congress on Digestive Diseases, Rome, June 22-26, 2002, and published as an abstract (Dig Liver Dis 3 [Suppl. 1]:A14, 2002).
PATIENTS AND METHODS Patients eligible for the study were 80 consecutive outpatients considered osteoporotic on the basis of lumbar (L2–L4) and femur bone mineral density (BMD), measured by dual-energy x-ray absorptiometry (Hologic QDR 1000/W) and according toWHO criteria (6). As a control group, we examined 160 male subjects without osteoporosis. Patients and controls were comparable on age, socioeconomic background, and smoking habits. Exclusion criteria for both patients and controls were malignancies, Paget’s disease of bone, hypogonadism, malabsorption due to gastrointestinal disorders, liver and thyroid diseases, and treatment in the last 3 months with drugs potentially affecting bone metabolism (such as glucocorticoids, anticonvulsivants, and cyclosporin) and with antibiotics potentially active against H. pylori. The local Ethical Committee approved this study and patients and controls gave their permission in writing. Patients were examined for serum antibodies to H. pylori using a commercially available ELISA with a sensitivity and specificity of 96% (Diesse, Diagnostica Senese, Monteriggioni, Italy). Those who were infected were examined for the presence of anti-CagA serum antibodies using a commercially available ELISA product with a sensitivity of 95% and a specificity of 90% (CagA-IgG; Genesis Diagnostics Ltd., Cambridgeshire, UK).
848
For each patient, in addition to BMD, we determined the following markers of bone turnover (the method and/or the instrument used are given in parentheses): serum concentrations of calcium (atomic absorption; Perkin Elmer, Beltsville, MD, USA); serum concentrations of phosphate (WaKo SD/200SD/300; Sclavo Diagnostics International, Italy); bone alkaline phosphatase (Tandem-R Ostase; Beckman Coulter Inc., Fullerton, CA, USA; interassay coefficient of variation [CV],
