CD44-specific antibody treatment and CD44 deficiency exert distinct effects on leukocyte recruitment in experimental arthritis.

CD44, the leukocyte adhesion receptor for hyaluronan, has been considered a therapeutic target on the basis of the robust anti-inflammatory effect of CD44-specific antibodies in animal models of immune-mediated diseases. However, CD44 deficiency does not provide substantial protection against inflammation. Using intravital video microscopy in a murine model of rheumatoid arthritis, we show that CD44 deficiency and anti-CD44 antibody treatment exert disparate effects on leukocyte recruitment in inflamed joints. Leukocyte rolling, which is increased in CD44-deficient mice, is promptly abrogated in anti-CD44-treated wild-type mice. CD44-specific antibodies also trigger platelet deposition on granulocytes and subsequent depletion of this leukocyte subset in the circulation. These in vivo effects require CD44 cross-linking and are reproducible with an antibody against Gr-1, a molecule that, like CD44, is highly expressed on granulocytes. Anticoagulant pretreatment, which prevents platelet deposition, mitigates both granulocyte depletion and the suppressive effect of CD44-specific antibody on joint swelling. Our observations suggest that cross-linking of prominent cell surface molecules, such as CD44 or Gr-1, can initiate a rapid self-elimination program in granulocytes through engagement of the coagulation system. We conclude that the robust anti-inflammatory effect of CD44-specific antibodies in arthritis is primarily the result of their ability to trigger granulocyte depletion.

Visualization and in situ analysis of leukocyte trafficking into the ankle joint in a systemic murine model of rheumatoid arthritis.

OBJECTIVE: To describe the kinetics of leukocyte migration into a distal joint during the development of chronic inflammation in a murine model of rheumatoid arthritis (RA), to identify leukocyte subpopulations recruited in the synovial vessels, and to test in real time the effects of an antiinflammatory compound on leukocyte-endothelial cell interactions in the arthritic joint. METHODS: We used intravital video microscopy (IVM), which was adapted to the microcirculation of the mouse ankle, to monitor the kinetics of leukocyte-endothelium interactions (rolling and firm adhesion) during the onset and progression of proteoglycan-induced arthritis (PGIA), a chronic autoimmune model of RA. Subpopulations of rolling and adherent leukocytes were identified by in vivo immunostaining. Leukocyte extravasation into the ankle joint was verified histologically. RESULTS: Between the onset of arthritis and the beginning of the destructive phase of PGIA, we found a steady increase in the number of leukocytes that exhibited firm adherence to the endothelium of synovial vessels, which clearly underscores the chronic, self-perpetuating character of joint inflammation in this autoimmune model. We showed, however, that granulocytes, and not T cells, constituted the major cell population that was continuously recruited to the inflamed ankle. Using IVM, we could detect instant changes in leukocyte adhesion behavior in the synovial vessels of the arthritic joint upon administration of a compound that antagonizes leukocyte rolling. CONCLUSION: IVM of the microcirculation of the mouse ankle could become an essential tool for investigating the mechanisms that regulate leukocyte migration to the joint in systemic models of RA as well as for preclinical testing of antiinflammatory therapies.

Insulin-like growth factor I gene microsatellite repeat, collagen type Ialpha1 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 biliary 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.

[Decreased bone mineral density and gene polymorphism in primary biliary cirrhosis]. / Csökkent csontásványianyag-tartalom és génpolimorfizmus primer biliaris cirrhosisban.

UNLABELLED: Genetic factors have been implicated in the pathogenesis of osteoporosis, which is a common disorder in primary biliary cirrhosis (PBC). Insulin-like growth factor I (IGF-I) gene microsatellite repeat polymorphism was found to be associated with osteoporosis in some studies and collagen type I alpha 1 (COLIA1) SP1 "s" allele was associated with lower bone mineral density (BMD) in PBC. IGF-I treatment restored osteopenia and reduced fibrogenesis in experimental cirrhosis. We investigated IGF-I and COLIA1 gene polymorphisms and BMD in Hungarian PBC patients. PATIENTS AND METHODS: 70 female patients with PBC were enrolled (mean age: 57.6 yrs, range: 37-76 yrs, each AMA M2 positive, stage II-IV). 139 age-matched female subjects served as controls (mean age: 55.9 yrs, range: 43-72 yrs). COLIA1 and IGF-I microsatellite repeat polymorphisms were determined by PCR. Bone mineral density (BMD) was measured by dual energy x-ray absorptiometry (Lunar, Prodigy, WI, USA) in lumbar spine (LS) and femoral neck (FN). RESULTS: The IGF-I polymorphism was not different between PBC patients (192/192 = 34.2%, 194/192 = 28.6%, other = 37.2%) and controls (192/192 = 38.2%, 194/192 = 30.9%, other = 30.9%). The genotype frequency of COLIA1 polymorphism was also not different between PBC patients (SS = 72.9%, Ss = 22.8% and ss = 4.3%) and controls (SS = 58.4%, Ss = 35.9% and ss = 5.7%), however the "s" allele was significantly less frequent in patients with PBC (p = 0.038). Osteoporosis was present in 22 patients (31.4%). The IGF-I 192/192 allele was associated with higher FN Z-score compared to other genotypes (p = 0.036). CONCLUSIONS: In contrast to previous studies the "s" allele was less frequent in patients with PBC, and its presence was not associated with lower bone mineral density. Since IGF-I polymorphism was associated to BMD, it may be hypothesized that IGF-I microsatellite repeat polymorphism together with other genetic and environmental factors may be involved in the complex regulation of BMD in PBC.

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+/-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.

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 PvuII and XbaI 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 PvuII (PP, 18.2%; Pp, 75.6%; pp, 6.2%) and XbaI (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 (t 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 PvuII and XbaI 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.