Genetic variation in the nuclear factor kappaB pathway in relation to susceptibility to rheumatoid arthritis

OBJECTIVE

To examine genetic association between rheumatoid arthritis (RA) and known polymorphisms in core genes of the nuclear factor (NF)kappaB pathway, the major intracellular pathway in RA pathogenesis.

METHODS

Discovery and replication sample sets of Spanish patients with RA and controls were studied. A total of 181 single nucleotide polymorphisms (SNPs) uniformly spaced along the genomic sequences of 17 core genes of the NFkappaB pathway (REL, RELA, RELB, NFKB1, NFKB2, NFKBIA, NFKBIB, NFKBIE, IKBKA, IKBKB, IKBKE, IKBKAP, KBRAS1, KBRAS2, MAP3K1, MAP3K14, TAX1BP1) were studied by mass spectrometry analysis complemented with 5'-nuclease fluorescence assays in the discovery set, 458 patients with RA and 657 controls. SNPs showing nominal significant differences were further investigated in the replication set of 1189 patients with RA and 1092 controls.

RESULTS

No clear reproducible association was found, although 12 SNPs in IKBKB, IKBKE and REL genes showed significant association in the discovery set. Interestingly, two of the SNPs in the IKBKE gene, weakly associated in the discovery phase, showed a trend to significant association in the replication phase. Pooling both sample sets together, the association with these two SNPs was significant.

CONCLUSION

We did not find any major effect among the explored members of the NFkappaB pathway in RA susceptibility. However, it is possible that variation in the IKBKE gene could have a small effect that requires replication in additional studies.

Prevalence, risk factors, and impact of knee pain suggesting osteoarthritis in Spain

OBJECTIVE

To estimate the point prevalence of knee pain suggesting osteoarthritis (OA) in the adult Spanish population. Secondary objectives were to examine the distribution of associated factors, as well as to assess the impact of knee pain on quality of life and function in the general population.

METHODS

A population survey was conducted in year 2000 for which 2,192 subjects over 20 years of age were selected by stratified polystage cluster sampling from the censuses of 20 towns. Trained rheumatologists administered structured interviews that permitted them to rule out the presence of rheumatic symptoms, and which included validated instruments to measure function and quality of life. We used the definition of clinical symptomatic knee OA of the American College of Rheumatology.

RESULTS

The estimated prevalence of knee pain suggesting OA in the general adult population is 10.2% (95% confidence interval: 7.9-12.5). Elderly women with fewer studies and from the lower social class, as well as those subjects involved in physically demanding jobs are more frequently affected. Obesity is also an important determinant for knee pain suggesting OA. Knee pain is associated to a significant decrease in functional ability and quality of life, even after adjustment for age, sex, and comorbidity.

CONCLUSION

The prevalence of knee pain suggesting OA in the general Spanish population is higher than expected, mainly related to a high rate of knee pain in women over 55. The proportion of very old persons and of those obese are important factors to take into account when comparing the rate of knee OA between populations.

The IL23R Arg381Gln non-synonymous polymorphism confers susceptibility to ankylosing spondylitis

OBJECTIVES

Recent results have shown that the IL23R gene, coding for a subunit of the interleukin-23 receptor, is strongly associated with autoimmunity. The aim of the current study was to investigate, for the first time, the possible involvement of the IL23R gene in genetic susceptibility to ankylosing spondylitis (AS).

METHODS

We carried out a case-control association study in which 365 patients with AS and 500 blood bank donors were included. Eight single nucleotide polymorphisms (SNPs) spanning the IL23R gene were selected as genetic markers for our association study and were genotyped using a Taqman 5' allelic discrimination assay.

RESULTS

Interestingly, we observed association of two of eight IL23R genotyped SNPs. The strongest effect was conferred by the non-synonymous rs11209026 (Arg381Gln) SNP (odds ratio 0.46 95% confidence interval 0.2 to 0.7 p = 0.001). Similarly, the IL23R rs1343151 SNP showed association with AS genetic susceptibility (odds ratio 0.68 95% confidence interval 0.55 to 0.83 p = 0.0002). After a conditional case-control test we observed that the effect of these two genetic variants was independent of linkage disequilibrium.

CONCLUSIONS

These results suggest that the IL23R gene seems to be involved in AS genetic predisposition.

Opposed independent effects and epistasis in the complex association of IRF5 to SLE

Genetic variation in the interferon regulatory factor 5 (IRF5) gene affects systemic lupus erythematosus (SLE) susceptibility. However, association is complex and incompletely defined. We obtained fourteen European sample collections with a total of 1383 SLE patients and 1614 controls to better define the role of the different IRF5 variants. Eleven polymorphisms were studied, including nine tag single nucleotide polymorphisms (SNPs) and two extra functional polymorphisms. Two tag SNPs showed independent and opposed associations: susceptibility (rs10488631, P<10(-17)) and protection (rs729302, P<10(-6)). Haplotype analyses showed that the susceptibility haplotype, identified by the minor allele of rs10488631, can be due to epistasis between three IRF5 functional polymorphisms. These polymorphisms determine increased mRNA expression, a splice variant with a different exon 1 and a longer proline-rich region in exon 6. This result is striking as none of the three polymorphisms had an independent effect on their own. Protection was independent of these polymorphisms and seemed to reside in the 5' side of the gene. In conclusion, our results help to understand the role of the IRF5 locus in SLE susceptibility by clearly separating protection from susceptibility as caused by independent polymorphisms. In addition, we have found evidence for epistasis between known functional polymorphisms for the susceptibility effect.

Cell Death and Apoptosis in Ostearthritic Cartilage

Osteoarthritis (OA) is the most common chronic joint disease in the elderly population, causing significant pain and disability. Because the cardinal feature of OA is a progressive loss of articular cartilage, a great portion of the research endeavour into the pathogenesis of OA has been focused on the regulation of matrix synthesis and degradation. The phenotypic stability and survival of the chondrocytes are essential for the maintenance of a proper cartilage matrix. This has lead to the long-standing assumption that cell death is a central feature in OA cartilage degeneration. The important role of apoptosis in OA has been demonstrated in in vitro and in vivo models. However, it should be noted that the relative contribution of apoptotic cell death in the pathogenesis of OA is still difficult to assess because of the chronic nature of the disease process. Therefore, the apoptosis of chondrocytes seems to be a potential target for therapeutic interventions in OA. The death receptor, mitochondrial and endoplasmic reticulum pathways are the major cellular pathways of apoptosis. Of all these elements involved in the apoptosis of chondrocytes, caspase inhibition has been studied with the most detail. Other molecules with the capacity to modulate mitochondria function, phosphatase (PP-1A/B) activity and pro-apoptosis stimuli (NO, prostaglandins, cytokines, ROS) could be excellent targets to block apoptosis of chondrocytes. Finally, the regulation of the natural inhibitors of apoptosis (c-FLIP, BAR, ARC and HC-gp39) could complement the other strategies to reduce cartilage degradation.

Glucosamine sulfate in the treatment of knee osteoarthritis symptoms: A randomized, double-blind, placebo-controlled study using acetaminophen as a side comparator

OBJECTIVE

To assess the effects of the prescription formulation of glucosamine sulfate (1,500 mg administered once daily) on the symptoms of knee osteoarthritis (OA) during a 6-month treatment course.

METHODS

Three hundred eighteen patients were enrolled in this randomized, placebo-controlled, double-blind trial in which acetaminophen, the currently preferred medication for symptomatic treatment of OA, was used as a side comparator. Patients were randomly assigned to receive oral glucosamine sulfate 1,500 mg once daily (n = 106), acetaminophen 3 gm/day (n = 108), or placebo (n = 104). The primary efficacy outcome measure was the change in the Lequesne index after 6 months. Secondary parameters included the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and response according to the Osteoarthritis Research Society International criteria. These outcome measures were assessed using an intent-to-treat analysis.

RESULTS

At baseline, the study patients had moderately severe OA symptoms (mean Lequesne index approximately 11 points). Glucosamine sulfate was more effective than placebo in improving the Lequesne score, with a final decrease of 3.1 points, versus 1.9 with placebo (difference between glucosamine sulfate and placebo -1.2 [95% confidence interval -2.3, -0.8]) (P = 0.032). The 2.7-point decrease with acetaminophen was not significantly different from that with placebo (difference -0.8 [95% confidence interval -1.9, 0.3]) (P = 0.18). Similar results were observed for the WOMAC. There were more responders to glucosamine sulfate (39.6%) and acetaminophen (33.3%) than to placebo (21.2%) (P = 0.004 and P = 0.047, respectively, versus placebo). Safety was good, and was comparable among groups.

CONCLUSION

The findings of this study indicate that glucosamine sulfate at the oral once-daily dosage of 1,500 mg is more effective than placebo in treating knee OA symptoms. Although acetaminophen also had a higher responder rate compared with placebo, it failed to show significant effects on the algofunctional indexes.

Mitochondrial activity is modulated by TNFalpha and IL-1beta in normal human chondrocyte cells

OBJECTIVE

Pro-inflammatory cytokines play an important role in osteoarthritis (OA). In osteoarthritic cartilage, chondrocytes exhibit an alteration in mitochondrial activity. This study analyzes the effect of tumor necrosis factor-alpha (TNFalpha) and interleukin-1beta (IL-1beta) on the mitochondrial activity of normal human chondrocytes.

MATERIALS AND METHODS

Mitochondrial function was evaluated by analyzing the activities of respiratory chain enzyme complexes and citrate synthase, as well as by mitochondrial membrane potential (Deltapsim) and adenosine triphosphate (ATP) synthesis. Bcl-2 family mRNA expression and protein synthesis were analyzed by RNase protection assay (RPA) and Western-blot, respectively. Cell viability was analyzed by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) and apoptosis by 4', 6-diamidino-2-phenylindole dihydrochloride (DAPI) stain. Glycosaminoglycans were quantified in supernatant by a dimethyl-methylene blue binding assay.

RESULTS

Compared to basal cells, stimulation with TNFalpha (10 ng/ml) and IL-1beta (5 ng/ml) for 48 h significantly decreased the activity of complex I (TNFalpha=35% and IL-1beta=35%) and the production of ATP (TNFalpha=18% and IL-1beta=19%). Both TNFalpha and IL-1beta caused a definitive time-dependent decrease in the red/green fluorescence ratio in chondrocytes, indicating depolarization of the mitochondria. Both cytokines induced mRNA expression and protein synthesis of the Bcl-2 family. Rotenone, an inhibitor of complex I, caused a significant reduction of the red/green ratio, but it did not reduce the viability of the chondrocytes. Rotenone also increased Bcl-2 mRNA expression and protein synthesis. Finally, rotenone as well as TNFalpha and IL-1beta, reduced the content of proteoglycans in the extracellular matrix of normal cartilage.

CONCLUSION

These results show that both TNFalpha and IL-1beta regulate mitochondrial function in human articular chondrocytes. Furthermore, the inhibition of complex I by both cytokines could play a key role in cartilage degradation induced by TNFalpha and IL-1beta. These data could be important for understanding of the OA pathogenesis.

SDS-CGE of proteins in microchannels made of SU-8 films

This work describes the SDS-CGE of proteins carried out in microchannels made of the negative photoresist EPON SU-8. Embedded electrophoretic microchannels have been fabricated with a multilayer technology based on bonding and releasing steps of stacked SU-8 films. This technology allows the monolithic integration of the electrodes in the device. A high wafer fabrication yield and mass production compatibility guarantees low costs and high reliability. A poly(methyl methacrylate) (PMMA) packaging allows an easy setup and replacement of the device for electrophoresis experiments. In addition, the wire-bonding step is avoided. The electrophoretic mobilities of four proteins have been measured in microchannels filled with polyacrylamide. Different pore sizes have been tested obtaining their Ferguson plots. Finally, a separation of two proteins (20 and 36 kDa) has been carried out confirming that this novel device is suitable for protein separation. A resolution of 2.75 is obtained. This is the first time that this SU-8 microfluidic technology has been validated for SDS-CGE of proteins. This technology offers better separation performance than glass channels, at lower costs and with an easy packaging procedure.

Follicular dendritic cells are related to bone marrow stromal cell progenitors and to myofibroblasts

Follicular dendritic cells (FDC) are involved in the presentation of native Ags to B cells during the secondary immune response. Some authors consider FDC to be hemopoietic cells, whereas others believe them to be mesenchymal cells. The low proportion of FDC in the lymphoid follicle, together with technical difficulties in their isolation, make these cells difficult to study. We show that Fibroblast Medium can be used successfully to isolate and maintain FDC lines. In this culture medium, we obtained 18 FDC lines from human tonsils, which proliferated for as long as 18 wk and showed a stable Ag phenotype as detected by flow cytometry and RT-PCR. FDC lines were CD45-negative and expressed Ags associated to FDC (CD21, CD23, CD35, CD40, CD73, BAFF, ICAM-1, and VCAM-1) and Ags specific for FDC (DRC-1, CNA.42, and HJ2). These cell lines were also able to bind B cells and secrete CXCL13, functional activities characteristic of FDC. Nevertheless, the additional expression of STRO-1, together with CD10, CD13, CD29, CD34, CD63, CD73, CD90, ICAM-1, VCAM-1, HLA-DR, alkaline phosphatase, and alpha-smooth muscle actin (alpha-SM actin) indicated that FDC are closely related to bone marrow stromal cell progenitors. The expression of alpha-SM actin also relates FDC with myofibroblasts. Like myofibroblasts, FDC lines expressed stress fibers containing alpha-SM actin and were able to contract collagen gels under the effect of TGFbeta1 and platelet-derived growth factor. These findings suggest that FDC are a specialized form of myofibroblast and derive from bone marrow stromal cell progenitors.

Cytokines, tumor necrosis factor-alpha and interleukin-1beta, differentially regulate apoptosis in osteoarthritis cultured human chondrocytes

OBJECTIVE

This study addresses the effects of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) on cell death in human chondrocytes.

METHODS

Osteoarthritis (OA) human chondrocytes stimulated with Actinomycin-D (ActD) were used as a cellular apoptotic model. Caspase family mRNA expression and protein synthesis were analyzed by the ribonuclease protection assay and Western-blot, respectively. Cell viability and apoptosis were evaluated using the 3-[4,5-dimethylthiazol-2yl] 2,5-diphenyl tetrazolium bromide (MTT) assay and flow cytometry, respectively. Prostaglandin E2 (PGE2) and nitric oxide (NO) were evaluated by enzyme-linked immunosorbent assay (ELISA) and the Griess method, respectively.

RESULTS

TNF-alpha and IL-1beta differentially affected the pattern of caspase mRNA expression by human chondrocytes. TNF-alpha induced a gradual increase in caspase-1 and -8 mRNA levels that was not seen with IL-1beta. The time sequence of caspase-3 and -7 inductions by TNF-alpha differs from that induced by IL-1beta. Cell viability was not modified by TNF-alpha or IL-1beta in cultured chondrocytes. Then, we employed ActD as a model to facilitate cell death. Treatment with TNF-alpha and ActD (TNF-alpha/ActD) increased cell death induced by ActD (23%). Treatment with IL-1beta and ActD (IL-1beta/ActD) did not modulate ActD-induced cell death. Similarly, IL-1beta/ActD did not induce an increase in the activation of caspase-3 and -7 and poly (ADP-ribose) polymerase (PARP) cleavage observed by the incubation with TNF-alpha/ActD. These different effects were not due to bcl-2 or mcl-1 levels. Inhibition of PGE2 synthesis by indomethacin increased the cell death induced by IL-1beta/Act-D (59%). An inhibitor of caspase-8 significantly reduced only the TNF-alpha/ActD-induced cell death (58%).

CONCLUSION

TNF-alpha and IL-1beta differentially regulate the apoptotic pathway in human chondrocytes. This difference is dependent on PGE2 and caspase-8 levels.

Mitochondrial proteomic characterization of human normal articular chondrocytes

OBJECTIVE

Mitochondrial dysfunctions have been associated with apoptosis, aging and osteoarthritis (OA). Chondrocyte mitochondrial proteins are attractive targets for the study of the metabolism of cartilage degradation. The copurification of "contaminating" proteins has been the major problem in all phases of mitochondrial proteome research. Therefore, we set up a procedure for the proteomic analysis of human chondrocyte mitochondrial proteins.

METHOD

Four types of protein extracts were obtained from primary cultured chondrocytes isolated from healthy donors: (1) initial total chondrocyte extract (CE), (2) cytosol-enriched supernatant fraction (CY), (3) crude mitochondria fraction (CM), and (4) pure mitochondria fraction (PM). Mitochondria were purified by density gradient ultracentrifugation. Mitochondrial proteins were separated by means of two-dimensional gel electrophoresis (2-DE) and silver stained. Protein spots were then identified by mass spectrometry using MALDI-TOF/TOF technology.

RESULTS

The best 2-DE reference map of mitochondrial proteome was constructed employing PM fraction. Thirty-nine percent of the identified proteins were functionally distributed in the mitochondria, 14% in the endoplasmic reticulum and 36% in the cytoplasm. Examining their biological function, 22% are involved in protein targeting, 12% in signaling, 12% in glycolysis, 10% in RNA, DNA or protein synthesis, 10% in oxidative phosphorylation and 4% in redox. The analysis of mitochondrial Mn-superoxide dismutase (SODM) revealed an age-dependent decrease of this protein.

CONCLUSION

PM fraction allowed the obtention of a high quality proteomic map for the study of mitochondrial proteins in human articular chondrocytes. This proteomic approach may be also efficient to analyze both quantitative and qualitative modulations of the mitochondrial proteome in human chondrocytes during aging and pathological conditions such as OA.

Cell Therapy: A Therapeutic Alternative to Treat Focal Cartilage Lesions

BACKGROUND

Human mesenchymal stem cells (MSCs) are present in most of the tissue matrix, taking part in their regeneration when injury or damage occurs. The aim of this study was to investigate the presence of cells with pluripotential characteristics in synovial membranes from osteoarthritic (OA) patients and the capacity of these cells to differentiate to chondrocytes.

METHODS

Synovial membranes (n = 8) from OA patients were digested with collagenase. Isolated cells were cultured with DMEM, 20% FBS, and FGFb10 ng/mL. Cells from second subculture were used to carry out phenotypic characterization experiments (flow cytometry analysis with 11 monoclonal antibodies) and chondrogenic differentiation experiments(micropellet cultured in chondrogenic medium). Chondrogenic differentiation of cells was assessment by quantification of cartilage extracellular matrix components by following techniques: Safranin O, Toluidine Blue, and Alcian Blue stains to detect proteoglycans and immunohistochemistry to detect type I and II collagen.

RESULTS

Flow cytometry analyses showed that in our population more than 90% of cells were positive for MSC markers: CD29 (95%), CD44 (90%), CD73 (95%), CD90 (98%). Cells were negative for hematopoietic markers (CD11b, CD34, and CD45). Furthermore, cells showed positive stain to multipotent markers such as CD117 (c-kit) (98%), CD166 (74%), and STRO-1 (88%) and to quiescent satellite cells like PAX-7 (35%). The micropellet analyses showed that the culture of these cells with TGFbeta-3 for 2 and 3 weeks stimulates proteoglycan and collagen type II synthesis. Both molecules are characteristic of hyaline articular cartilage.

CONCLUSION

In this work, we demonstrate the presence of a cellular population with MSC characteristics in synovial tissue from OA patients. As MSC takes part in reparative processes of adult tissues, these cells could play an important role in OA pathogenesis and treatment.

Phosphatase-1 and -2A inhibition modulates apoptosis in human osteoarthritis chondrocytes independently of nitric oxide production

OBJECTIVE

To characterise the role of phosphatase-1 and -2A (PP1/2A) in the modulation of apoptosis in human osteoarthritis (OA) chondrocytes.

METHODS

Human OA chondrocytes were isolated from cartilage obtained from the femoral heads of patients undergoing joint replacement surgery. Cell viability was evaluated by MTT assay. Apoptosis was quantified by ELISA, which measures DNA fragmentation. Nitric oxide (NO) production was evaluated by the Greiss method, and inducible nitric oxide synthase (iNOS) protein synthesis was studied by western blotting.

RESULTS

Inhibition of PP1/2A by the specific inhibitor okadaic acid (OKA) dose and time dependently caused a reduction of cell viability (OKA at 50 nmol/l: a reduction to 60% and 43% at 48 and 72 hours, respectively). Genomic DNA from chondrocytes treated with OKA at 50 and 100 nmol/l for 48 hours displayed increased internucleosomal DNA fragmentation by 11 and 13 fields, respectively. Light microscopy and DAPI studies showed that OKA induced DNA condensation and fragmentation, typical of death by apoptosis. The caspase inhibitors Z-VAD-FMK and Z-DEVD-FMK increased cell viability, reduced by OKA at 50 nmol/l to 87% and 73%, respectively. OKA did not increase iNOS protein synthesis or NO production.

CONCLUSION

PP1/2A modulate apoptosis in human OA chondrocytes; this is independent of NO production but dependent on caspases.

Fabrication of SU-8 multilayer microstructures based on successive CMOS compatible adhesive bonding and releasing steps

This paper describes a novel fabrication process based on successive wafer-level bonding and releasing steps for stacking several patterned layers of the negative photoresist EPON SU-8. This work uses a polyimide film to enhance previous low temperature bonding technology. The film acts as a temporary substrate where the SU-8 is photopatterned. The poor adhesion between the polyimide film and SU-8 allows the film to be released after the bonding process, even though the film is still strong enough to carry out photolithography. Using this technique, successive adhesive bonding steps can be carried out to obtain complex 3-D multilayer structures. Interconnected channels with smooth vertical sidewalls and freestanding structures are fabricated. Unlike previous works, all the layers are photopatterned before the bonding process yielding sealed cavities and complex three-dimensional structures without using a sacrificial layer. Adding new SU-8 layers reduces the bonding quality because each additional layer decreases the thickness uniformity and increases the polymer crosslinking level. The effect of these parameters is quantified in this paper. This process guarantees compatibility with CMOS electronics and MEMS. Furthermore, the releasing step leaves the input and the output of the microchannels in contact with the outside world, avoiding the usual slow drilling process of a cover. Hence, in addition to the straightforward integration of electrodes on a chip, this fabrication method facilitates the packaging of these microfluidic devices.

Effect of nitric oxide on mitochondrial respiratory activity of human articular chondrocytes

OBJECTIVE

To investigate the effect of nitric oxide (NO) on mitochondrial activity and its relation with the apoptosis of human articular chondrocytes.

MATERIALS AND METHODS

Mitochondrial function was evaluated by analysing respiratory chain enzyme complexes, citrate synthase (CS) activities, and mitochondrial membrane potential (Delta psi m). The activities of the mitochondrial respiratory chain (MRC) complexes (complex I: NADH CoQ(1) reductase, complex II: succinate dehydrogenase, complex III: ubiquinol cytochrome c reductase, complex IV: cytochrome c oxidase) and CS were measured in human articular chondrocytes isolated from normal cartilage. The Delta psi m was measured by 5,5',6,6'-tetracholoro-1,1',3,3'-tetraethylbenzimidazole carbocyanide iodide (JC-1) using flow cytometry. Apoptosis was analysed by flow cytometry. The mRNA expression of caspases was analysed by ribonuclease protection analysis and the detection of protein synthesis by western blotting. Sodium nitroprusside (SNP) was used as an NO compound donor.

RESULTS

SNP at concentrations higher than 0.5 mmol/l for 24 hours induced cellular changes characteristic of apoptosis. SNP elicited mRNA expression of caspase-3 and caspase-7 and down regulated bcl-2 synthesis in a dose and time dependent manner. Furthermore, 0.5 mM SNP induced depolarisation of the mitochondrial membrane at 5, 12, and 24 hours. Analysis of the MRC showed that at 5 hours, 0.5 mM SNP reduced the activity of complex IV by 33%. The individual inhibition of mitochondrial complex IV with azide modified the Delta psi m and induced apoptosis.

CONCLUSIONS

This study suggests that the effect of NO on chondrocyte survival is mediated by its effect on complex IV of the MRC.

Prevalence of HLA-B27 and subtypes of HLA-B27 associated with ankylosing spondylitis in Galicia, Spain

OBJECTIVE

To assess the prevalence of HLA-B27 and its subtypes in both the normal population and in patients with Ankylosing Spondylitis (AS) in Galicia, Northwest Spain.

METHODS

The prevalence of HLA-B27 in the normal population was determined by checking the number of HLA-B27 positive samples in 308 subjects from different areas of Galicia who had donated organs over a period of 4 years. A total of 106 patients with the diagnosis of AS, according to the modified New York clinical criteria for definitive ankylosing spondylitis, were collected from three very representative areas of Galicia. HLA-B27 was determined by PCR using the primers E91s and E136as, while 11 subtypes of HLA-B27 were analyzed using a commercial kit.

RESULTS

The prevalence of HLA-B27 in organ donors was 9.34%. HLA-B27 was present in 94.3% of patients with AS. Subtypes B*2701, B*2709 and B*2710 were not found. The subtypes found in the normal population were; B*2705 (79.5%), B*2702 (18%) and B*2708 (2.5%). The subtypes associated with AS were B*2705 (88%) and B*2702 (12%).

CONCLUSION

The prevalence of HLA-B27 in Galicia was 9.34%, which is higher than previously published in Spain. The frequency of the subtypes associated with AS was similar to that reported for other Spanish regions.

The biological action of hyaluronan on human osteoartritic articular chondrocytes: the importance of molecular weight

OBJECTIVES

The intra-articular injection of hyaluronan (HA) was originally used in the treatment of osteoarthritis (OA) to increase the viscosity of synovial fluid. However, some findings suggest that the activity of HA cannot be solely explained by its biomechanical properties. The aim of this study was to analyze the in vitro biological effects of HA on human OA chondrocytes and the impact of its molecular weight (MW) on those effects.

METHODS

Cells were isolated from cartilage obtained during joint replacement surgery in OA patients. The chondrocytes were cultured for 24 hours to detect prostaglandin E2 (PGE2) and for 48 hours to measure nitric oxide (NO), after which they were pre-incubated with HA and stimulated with interleukin-1 (IL-1) at 5 ng/ml. Two commercial HA preparations with different MWs were used: Hyalgan (500-730 kDa, HA, Bioibérica S.A.) and Synvisc (hylan of 6,000 kDa, Biomatrix Inc). NO was detected by the Greiss reaction and PGE2 was quantified by a commercial EIA in the supernatant. Apoptosis was induced by an NO donor (sodium nitroprusside, SNP) and the effect of HA on apoptosis was quantified by flow cytometry.

RESULTS

Neither HA preparation studied had any effect on the basal production of NO or PGE2. However, the 500-730 kDa HA at 200 microg/ml reduced the synthesis of both IL-1-induced NO and PGE2 by 70% and 45% respectively. Furthermore both HA preparations at 200 microg/ml decreased the apoptosis induced by SNP, 500-730 kDa to 40% and 6,000 kDa to 36%.

CONCLUSION

HA may induce biological effects in addition to acting as a viscoelastic substance. This study suggests that HA preparations are different due to differences in biological activity resulting from MW.

Human decidual stromal cells express CD34 and STRO-1 and are related to bone marrow stromal precursors

Decidual stromal cells (DSC) are the main cellular component of the human decidua, but thus far their ascription to a given cell lineage is uncertain. In previous studies, these cells have been isolated and maintained in culture, and their antigen phenotype has been analysed to determine their affiliation. However, the presence in the culture medium of high proportions of fetal calf serum (FCS) may inhibit the expression of some surface antigens. In the present study, we show by flow cytometry that CD34 is rapidly down-regulated in human DSC cultured in RPMI 1640 with 20% FCS. For this reason, we used fibroblast medium, which contains only a small proportion (2%) of FCS, to isolate and culture these cells. Under these conditions DSC exhibited a stable antigen phenotype highly similar to that of these cells in vivo. Flow cytometry results confirmed that DSC cultured in fibroblast medium expressed CD34 protein, and reverse transcription-polymerase chain reaction findings showed that they have CD34 mRNA. Decidual stromal cells were also positive for STRO-1, an antigen that identifies stromal precursors of the bone marrow which also expresses CD34. The expression of CD10, CD13, alkaline phosphatase and alpha-smooth muscle actin by DSC, and the absence of expression of CD14 and CD45, further confirmed their relationship with the stromal precursors.

Aceclofenac increases the synthesis of interleukin 1 receptor antagonist and decreases the production of nitric oxide in human articular chondrocytes

OBJECTIVE

Interleukin 1 receptor antagonist (IL-1Ra) may play an important role in cartilage degradation by inhibiting IL-1 activity and therefore blocking IL-1 stimulation of prostaglandin E2 (PGE2) synthesis. Nitric oxide (NO) formation is increased during inflammation. High concentrations of NO exert negative effects on chondrocyte functions. We investigated the possible effects of 3 different nonsteroidal antiinflammatory drugs (NSAID; aceclofenac, piroxicam, aspirin) on IL-1Ra and NO production in human articular chondrocytes.

METHODS

Normal and osteoarthritic (OA) cartilage samples were obtained from autopsy and prosthetic joint surgery, respectively. Chondrocytes were isolated and stimulated with 4 different stimuli: IL-1, tumor necrosis factor-alpha (TNF-alpha), lipopolysaccharide (LPS), and insulin-like growth factor (IGF). The 3 NSAID were added simultaneously to each different concentration of stimulus. IL-1Ra was measured in supernatant by ELISA; nitrites were quantified by the Griess reaction; PGE2 level was measured by enzyme immunoassay.

RESULTS

OA samples spontaneously produced higher levels of IL-1Ra than normal samples (130+/-2.3 vs 30+/-3.1 pg/mI). IL-1, TNF-alpha, and LPS produced dose dependent increases in synthesis of IL-1Ra. In their presence, IL-1Ra was detected in supernatant at 48 h, but its highest level was measured at 144 h. The most potent stimulus was IL-1, followed by TNF-alpha. Fetal bovine serum and IGF in turn did not modify the basal levels of IL-1Ra. In contrast to piroxicam and aspirin, aceclofenac 10 microg/ml and TNF-alpha 10 ng/ml increased almost 46 times the basal amount of IL-1Ra produced by OA chondrocytes. Additionally, aceclofenac and aspirin inhibited NO synthesis. Finally, the 3 NSAID reduced the levels of PGE2 detected after stimulation with IL-1.

CONCLUSION

Proinflammatory stimuli induce IL-IRa synthesis in human articular chondrocytes. Aceclofenac may modulate PGE2 production by increasing IL-IRa production and decreasing NO synthesis. Some NSAID exert diverse prostaglandin independent effects.

Solid-state NMR data support a helix-loop-helix structural model for the N-terminal half of HIV-1 Rev in fibrillar form

Rev is a 116 residue basic protein encoded by the genome of human immunodeficiency virus type 1 (HIV-1) that binds to multiple sites in the Rev response element (RRE) of viral mRNA transcripts in nuclei of host cells, leading to transport of incompletely spliced and unspliced viral mRNA to the cytoplasm of host cells in the latter phases of the HIV-1 life cycle. Rev is absolutely required for viral replication. Because Rev aggregates and fibrillizes in solution at concentrations required for crystal growth or liquid state NMR measurements, high-resolution structural characterization of full-length Rev has not been possible. Previously, circular dichroism studies have shown that approximately 50 % of the Rev sequence adopts helical secondary structure, predicted to correspond to a helix-loop-helix structural motif in the N-terminal half of the protein. We describe the application of solid-state NMR techniques to Rev fibrils as a means of obtaining site-specific, atomic-level structural constraints without requiring a high degree of solubility or crystallinity. Solid-state NMR measurements, using the double-quantum chemical shift anisotropy and constant-time double-quantum-filtered dipolar recoupling techniques, provide constraints on the phi and psi backbone dihedral angles at sites in which consecutive backbone carbonyl groups are labeled with (13)C. Quantitative analysis of the solid-state NMR data, by comparison with numerical simulations, indicates helical phi and psi angles at residues Leu13 and Val16 in the predicted helix 1 segment, and at residues Arg39, Arg 42, Arg43, and Arg44 in the predicted helix 2 segment. These data represent the first site-specific structural constraints from NMR spectroscopy on full-length Rev, and support the helix-loop-helix structural model for its N-terminal half.

Elongation of the BH8 beta-hairpin peptide: Electrostatic interactions in beta-hairpin formation and stability

An elongated version of the de novo designed beta-hairpin peptide, BH8, has allowed us to gain insight into the role of electrostatic interactions in beta-hairpin stability. A Lys-Glu electrostatic pair has been introduced by adding a residue at the beginning and at the end of the N-terminal and C-terminal strands, respectively, of the beta-hairpin structure, in both orientations. The two resulting peptides and controls having Ala residues at these positions and different combinations of Ala with Lys, or Glu residues, have been analyzed by nuclear magnetic resonance (NMR), under different pH and ionic strength conditions. All of the NMR parameters, in particular the conformational shift analysis of Calpha protons and the coupling constants, (3)J(HNalpha), correlate well and the population estimates are in reasonable agreement among the different methods used. In the most structured peptides, we find an extension of the beta-hairpin structure comprising the two extra residues. Analysis of the pH and salt dependence shows that ionic pairs contribute to beta-hairpin stability. The interaction is electrostatic in nature and can be screened by salt. There is also an important salt-independent contribution of negatively charged groups to the stability of this family of beta-hairpin peptides.

Effect of cryopreservation on human articular chondrocyte viability, proliferation, and collagen expression

Autotransplantation of human chondrocytes is an alternative therapeutic treatment for focal lesions of cartilage. During the process of isolation and culture of chondrocytes some problems that render the implantation of the cells unsuitable can occur. For security, some cells must be stored using cryopreservation. The objective of this study was to analyze the effect of cryopreservation on cellular viability, proliferation, and collagen expression of human chondrocytes. Human osteoarthritic cartilage (n = 23) was obtained and transferred to a sterile flask containing Dulbecco's modified Eagle's medium (DMEM) and antibiotics. Chondrocytes were isolated, cultured for 3-4 weeks, and frozen in DMEM containing 10% human serum and 10% dimethyl sulfoxide by use of three different protocols. A cellular fraction was frozen directly to -80 degrees C (Protocol I). Another fraction was directly frozen to -80 degrees C and 24 h later introduced into liquid nitrogen (Protocol II). The last aliquot was frozen with controlled freezing using a freezing rate of -1 degrees C/min to a temperature of -40 degrees C, 2 degrees C/min to -60 degrees C, and 5 degrees C/min to -150 degrees C (Protocol III). Cells were cryopreserved for 2 weeks. Cells from each cryopreservation method were then cultured for 7 days and cellular proliferation was evaluated by the counting of the total cells in each flask. Cryopreservation had a negative effect on chondrocyte survival and proliferation. The survival after cryopreservation with the three protocols was 70-75%. There was no significative difference between the methods used to cryopreserve (P = 0.4117). However, there was a significant difference among the donors (P = 0.0111). Cellular proliferation of chondrocytes was reduced by cryopreservation (P = 0.024). The rate of proliferation of different groups was control samples 6.56, Protocol I 4.66, Protocol II 4.69, and Protocol III 5.58. Statistical analysis showed that the programmed protocol was the best method to preserve cellular functions. Chondrocytes were able to express collagen type II 1 week after cryopreservation. Cryopreservation modifies the survival and proliferation of chondrocytes. Of all protocols used to cryopreserve, the programmed protocol seems to be the best technique. Cryopreservation does not alter the collagen type II expression.

Removal of bowel aerobic gram-negative bacteria is more effective than immunosuppression with cyclophosphamide and steroids to decrease natural alpha-galactosyl IgG antibodies

Natural alpha-Galactosyl (Gal) antibodies play an important role in the rejection of pig xenografts by humans and Old World monkeys. In this study we investigate the efficacy of two different strategies to reduce the serum level of natural anti-Gal antibodies. On the one hand, removal of aerobic gram-negative bacteria from the intestinal flora, because anti-Gal antibodies appear to be produced as a result of the continuous sensitization by these microorganisms. On the other hand, we studied the effect on these antibodies of an immunosuppressive regimen of cyclophosphamide and steroids. Ten baboons were treated for three months with norfloxacin (Nor Group; n=6) or cyclophosphamide and steroids (CyP Group; n=4). A further four baboons did not receive any treatment (Control Group). Aerobic gram-negative bacteria became negative in stools of the Nor Group after two weeks of treatment, and remained undetectable until week 7. Thereafter, a gradual increase on the fecal concentration of aerobic gram-negative bacteria was observed despite the norfloxacin treatment. The mean anti-Gal IgG in the Nor Group gradually declined from week 4 to 9 to a mean of 62.7 +/- 18% of the baseline level, and during this period were significantly lower than in the CyP (P<0.02) and the Control (P<0.05) groups. No differences were observed between the three groups during the 16 weeks of follow-up in serum levels of anti-Gal IgM, hemolytic anti-pig antibodies, total IgG, IgM and IgA. In conclusion, removal of normal aerobic gram-negative bacteria from the intestinal flora is more effective than immunosuppression with CyP and steroids in reducing the level of natural anti-Gal antibodies, although there is no discernible effect on IgM antibodies.