Gene polymorphisms in primary biliary cirrhosis: association with the disease and hepatic osteopathy

Genetic factors have been implicated in the pathogenesis of osteoporosis, a common disorder in primary biliary cirrhosis (PBC). Estrogen receptor-alpha gene (ER-�), vitamin-D-receptor gene (VDR) and IL-1-receptor-antagonist gene (IL-1RN) are all attractive candidates for osteoporosis susceptibility. Furthermore insulin-like growth factor-I (IGF-I) gene microsatellite repeat polymorphism was found to be associated with osteoporosis in some studies and collagen-I�1 (COLIA1) Sp1 s allele was associated with lower bone mineral density (BMD) in one study in PBC. IGF-I treatment restored osteopenia and reduced fibrogenesis in experimental cirrhosis. In this study we summarize our results on polymorphisms of the above genes and bone disease in Hungarian PBC patients. Patients and methods: 70 female patients with PBC were enrolled (age:57.6yrs, range:37-76yrs, each AMA-M2 positive, stage II-IV). 139 age-matched female subjects served as controls (age: 55.9 yrs, range:43-72 yrs). COLIA1 Sp1 and IGF-I microsatellite polymorphisms were determined by PCR in all patients and controls. VDR BsmI, IL-1RN variable-number tandem repeat (VNTR) and ER-� PvuII and XbaI polymorphisms were detected in 33 patients and controls. BMD was measured by dual energy x-ray absorptiometry (Lunar,Prodigy,USA) in lumbar spine (LS) and femoral neck (FN). Results: There was no difference in IGF-I microsatellite repeat polymorphism (192/192=34.2%, 194/192=28.6%, other=37.2%) and COLIA1 Sp1 polymorphism (SS=72.9%, Ss=22.8% and ss=4.3%) and IL-1 VNTR polymorphism between PBC patients and controls, however, the COLIA1 Sp1 s allele was significantly less frequent in patients with PBC (p=0.038). The genotype frequency of VDR BsmI (BB=57.5%, Bb=33.3%, bb=9.1%, p=0.01) and ER-a PvuII (PP=18.2%, Pp=75.6%, pp=6.2%, p=0.03) and XbaI (XX=9.1%, Xx=90.9%, xx=0%, p=0.0003) of the patients was different from that of the control group, with higher frequency of the BB, Pp and Xx genotypes in PBC. Osteoporosis (t score<-2.5) was detected in 22 patients (31.4%). Osteoporotic patients were elder and had longer disease history (p=0.01 for both). An association was found between the IGF-I genotypes and ODM data, the 192/192 genotype was associated with higher FN Z-score compared to other genotypes (p=0.036). Conclusions: In contrast to previous studies the COLIA1 Sp1 s allele was less frequent in patients with PBC, and its presence was not associated with BMD. We confirmed previous findings on higher frequency of VDR BsmI BB genotype in patients with PBC. The ER-α PvuII and XbaI Pp and Xx genotypes were more frequent in PBC patients, while IL-1RN VNTR and IGF-I microsatellite repeat polymorphism was not different. Since IGF-I polymorphism was associated to BMD, it may be hypothesized that not COLIA1 but IGF-I together with other genetic and environmental factors may be involved in the complex regulation of BMD in PBC

Vitamin D receptor, oestrogen receptor-alpha gene and interleukin-1 receptor antagonist gene polymorphisms in Hungarian patients with primary biliary cirrhosis

Background Genetic factors have been implicated in the pathogenesis of osteoporosis, a common disorder in primary biliary cirrhosis. Oestrogen receptor-alpha gene, vitamin D receptor gene and interleukin-1 receptor antagonist gene are all attractive candidates for osteoporosis susceptibility. We investigated the polymorphisms of the above genes and bone disease in Hungarian patients with primary biliary cirrhosis. Patients and methods Thirty-three female patients with primary biliary cirrhosis were enrolled (age range, 39-72 years; anti-mitochondrial antibody M2 positive, stage II-IV). Eighty-four healthy and 76 osteoporotic age matched female subjects served as controls. Vitamin D receptor BsmI, interleukin-1 receptor antagonist gene variable-number tandem repeat and oestrogen receptor-alpha Pvull and Xbal polymorphisms were determined. Bone mineral density was measured by dual energy X-ray absorptiometry (XR26, Norland) in lumbar spine and femoral neck. Results The genotype frequency of vitamin D receptor BsmI (BB, 57.5%; Bb, 33.3%; bb, 9.1%) and oestrogen receptor-alpha Pvull (PP, 18.2%; Pp, 75.6%; pp, 6.2%) and Xbal (XX, 9.1%; Xx, 90.9%; xx, 0%) of the primary biliary cirrhosis patients was different from that of the healthy and osteoporotic control groups (P < 0.03 for each). Osteoporosis Q score < -2.5) was present in 42.4% of the patients. Osteoporotic primary biliary cirrhosis patients were older and had a longer disease history (P = 0.01 for both). No association was found between the polymorphisms and bone mineral density values at either position. Conclusions We confirmed previous findings concerning the higher frequency of vitamin D receptor BsmI BB genotype in patients with primary biliary cirrhosis. The oestrogen receptor-alpha Pvull and Xbal Pp and Xx genotypes were more frequent in primary biliary cirrhosis patients, while interleukin-1 receptor antagonist gene variable-number tandem repeat polymorphism was not different. Since none of the polymorphisms was associated with bone mineral density, it is unlikely that these polymorphisms are essential in predicting bone mineral density in primary biliary cirrhosis

High serum osteoprotegerin and low RANKL in primary biliary cirrhosis

Background/Aims: Osteoprotegerin is decoy receptor for osteoclast activating factor, RANKL, and impairs osteoclast funtion. Since osteoporosis is common in primary biliary cirrhosis (PBC), we investigated osteoprotegerin, RANKL and markers of bone turnover in PBC. Methods: Serum osteoprotegerin, RANKL, osteocalcin (OC) and C-terminal cross-linking telopeptide of type I collagen (CTX-I) were measured by ELISA in 41 patients with PBC, 16 women with chronic hepatitis C (CHC), and as controls in 44 age-matched healthy and 74 post-menopausal osteopenic otherwise healthy women. Results: Serum osteoprotegerin levels were higher in PBC patients (7.8+/-3.0 pmol/l) than in healthy controls (4.4+/-2.3 pmol/l) and osteopenic women (4.0+/-1.0 pmol/l, P<0.0001 for both). RANKL levels were lower in PBC (0.9&PLUSMN;1.8 pmol/l, P<0.0001) than in healthy controls (1.3+/-0.5 pmol/l). In CHC both osteoprotegerin (9.7+/-4.2 pmol/l) and RANKL (3.2+/-4.7 pmol/l) were elevated compared to the control groups (P<0.0001, for both). There was a positive correlation between serum osteoprotegerin and OC, CTX-I and AST but not with bone mineral density in PBC. Conclusions: The mechanisms and role of elevated osteoprotegerin and low RANKL in PBC are unclear, but it might partly represent a compensatory mechanism to negative balance of bone remodeling. High OPG and RANKL levels found in CHC might suggest that inflammatory process in the liver could also contribute to the elevation of osteoprotegerin

Insulin-like growth factor I gene microsatellite repeat, collagen type I alpha 1 gene Sp1 polymorphism, and bone disease in primary biliary cirrhosis

Background Genetic factors have been implicated in the pathogenesis of osteoporosis, a common disorder in primary biliary cirrhosis. Insulin-like growth factor I (IGF-I) gene microsatellite repeat polymorphism was found to be associated with osteoporosis in some studies, and collagen-Ialpha1 (COLIA1) Sp1 s allele was associated with lower bone mineral density in primary biliary cirrhosis. IGF-I treatment restored osteopenia and reduced fibrogenesis in experimental cirrhosis. We investigated IGF-I and COLIA1 gene polymorphisms and bone mineral density in Hungarian primary biliary cirrhosis patients. Patients and methods Seventy female patients with primary biliary cirrhosis were enrolled (mean age 57.6 years, range 37-76 years; all anti-mitochondrial antibody M2-positive; stage II-IV). One hundred and thirty-nine age-matched female subjects served as controls (mean age 55.9 years, range 43 - 72 years). COLIA1 and IGF-I polymorphisms were determined by polymerase chain reaction. Bone mineral density was measured by dual-energy X-ray absorptiometry in the lumbar spine and femoral neck. Results The IGF-I was not different between primary biliary cirrhosis patients and controls. The genotype frequency of COLIA1 polymorphism was also not different between primary biliary cirrhosis patients and controls. However, the s allele was significantly less frequent in patients with primary billary cirrhosis. Osteoporosis was detected in 22 patients. The IGF-I 192/192 genotype was associated with higher femoral-neck z-scores compared with other genotypes. Conclusion In contrast to previous studies, the s allele was less frequent in patients with primary biliary cirrhosis, and its presence was not associated with bone mineral density. Since IGF-I polymorphism was associated with bone mineral density, it may be hypothesised that not COLIA1 but IGF-I together with other genetic and environmental factors may be involved in the complex regulation of bone mineral density in primary biliary cirrhosis