Effect of hydrogen sulfide sources on inflammation and catabolic markers on interleukin 1β-stimulated human articular chondrocytes

OBJECTIVE

Hydrogen sulfide (H2S), the third gasotransmitter together with NO and CO, is emerging as a regulator of inflammation. To test if it might offer therapeutic value in the treatment of osteoarthritis (OA) we evaluated the effects of two exogenous sources of H2S, NaSH and GYY4137, on inflammation and catabolic markers that characterize OA.

METHOD

Human chondrocytes (CHs) were isolated from OA tissue. Cells were stimulated with a pro-inflammatory cytokine (interleukin-1β, IL1β, 5 ng/ml) and the ability of the two H2S sources to ameliorate its effects on the cells was tested. Nitric oxide (NO) production was quantified through the Griess reaction. Protein levels of inducible NO synthase (NOS2) and matrix metalloproteinase 13 (MMP13) were visualized through immunocytochemistry (ICC). Relative mRNA expression was quantified with qRT-PCR. Prostaglandin-2 (PGE-2), interleukin 6 (IL6) and MMP13 levels were measured with specific EIAs. NFκB nuclear translocation was visualized with immunofluorescence.

RESULTS

Both H2S sources led to significant reductions in NO, PGE-2, IL6 and MMP13 released by the cells and at the protein level. This was achieved by downregulation of relevant genes involved in the synthesis routes of these molecules, namely NOS2, cyclooxigenase-2 (COX2), prostaglandin E synthase (PTGES), IL6 and MMP13. NFκB nuclear translocation was also reduced.

CONCLUSION

NaSH and GYY4137 show anti-inflammatory and anti-catabolic properties when added to IL1β activated osteoarthritic CHs. Supplementation with exogenous H2S sources can regulate the expression of relevant genes in OA pathogenesis and progression, counteracting IL1β pro-inflammatory signals that lead to cartilage destruction in part by reducing NFκB activation.

Biochemical evidence for gap junctions and Cx43 expression in immortalized human chondrocyte cell line: a potential model in the study of cell communication in human chondrocytes

OBJECTIVE

The development of chondrocytic cell lines has enabled the investigation of the role of cellular phenotype and mechanisms in articular cartilage biology and physiopathology of several rheumatic diseases. Among them, the T/C-28a2 cell line has become a common tool in cartilage research. Recent results from our group have revealed that primary human chondrocytes in tissue and in monolayer culture contain high levels of connexin 43 (Cx43) and are able to directly communicate through gap junction (GJ) channels. These results challenge the existing thesis of cartilage physiology, that chondrocytes do not have the capacity to physically communicate with each other. Established cell lines offer the advantage of convenience and uniformity; however, the establishment process may cause a disruption of GJ. This study was performed to investigate if T/C-28a2 cells contain Cx43 protein and form functional channels.

METHODS

Cx43 was characterized by RT-qPCR, Western blotting, and immunohistochemistry (IHC). Electrophysiology experiments, Lucifer Yellow (LY) uptake, electroporation in situ and scrape loading assay were performed to test the functionality of GJs.

RESULTS

T/C-28a2 cells express Cx43. Electrophysiology experiments and LY uptake confirmed the capacity of these cells to communicate through GJ channels, although these cells contain significant levels of active c-Src kinase, presumably due to their immortalization with the Simian Virus 40 large T antigen. The results were validated using primary chondrocytes (PC).

CONCLUSIONS

These results reveal that the T/C-28a2 line may provide a useful in vitro model for the study of Cx43 function and cell communication to understand the physiology of chondrocytes and cartilage.

The Splicing Factor SRSF1 as a Marker for Endothelial Senescence

Aging is the major risk factor per se for the development of cardiovascular diseases. The senescence of the endothelial cells (ECs) that line the lumen of blood vessels is the cellular basis for these age-dependent vascular pathologies, including atherosclerosis and hypertension. During their lifespan, ECs may reach a stage of senescence by two different pathways; a replicative one derived from their preprogrammed finite number of cell divisions; and one induced by stress stimuli. Also, certain physiological stimuli, such as transforming growth factor-β, are able to modulate cellular senescence. Currently, the cellular aging process is being widely studied to identify novel molecular markers whose changes correlate with senescence. This review focuses on the regulation of alternative splicing mediated by the serine-arginine splicing factor 1 (SRSF1, or ASF/SF2) during endothelial senescence, a process that is associated with a differential subcellular localization of SRSF1, which typically exhibits a scattered distribution throughout the cytoplasm. Based on its senescence-dependent involvement in alternative splicing, we postulate that SRSF1 is a key marker of EC senescence, regulating the expression of alternative isoforms of target genes such as endoglin (ENG), vascular endothelial growth factor A (VEGFA), tissue factor (T3), or lamin A (LMNA) that integrate in a common molecular senescence program.

Umbilical cord as a mesenchymal stem cell source for treating joint pathologies

Articular cartilage disorders and injuries often result in life-long chronic pain and compromised quality of life. Regrettably, the regeneration of articular cartilage is a continuing challenge for biomedical research. One of the most promising therapeutic approaches is cell-based tissue engineering, which provides a healthy population of cells to the injured site but requires differentiated chondrocytes from an uninjured site. The use of healthy chondrocytes has been found to have limitations. A promising alternative cell population is mesenchymal stem cells (MSCs), known to possess excellent proliferation potential and proven capability for differentiation into chondrocytes. The “immunosuppressive” property of human MSCs makes them an important candidate for allogeneic cell therapy. The use of allogeneic MSCs to repair large defects may prove to be an alternative to current autologous and allogeneic tissue-grafting procedures. An allogeneic cell-based approach would enable MSCs to be isolated from any donor, expanded and cryopreserved in allogeneic MSC banks, providing a readily available source of progenitors for cell replacement therapy. These possibilities have spawned the current exponential growth in stem cell research in pharmaceutical and biotechnology communities. Our objective in this review is to summarize the knowledge about MSCs from umbilical cord stroma and focus mainly on their applications for joint pathologies.

Insights into the genetic architecture of osteoarthritis from stage 1 of the arcOGEN study

Objectives

The genetic aetiology of osteoarthritis has not yet been elucidated. To enable a well-powered genome-wide association study (GWAS) for osteoarthritis, the authors have formed the arcOGEN Consortium, a UK-wide collaborative effort aiming to scan genome-wide over 7500 osteoarthritis cases in a two-stage genome-wide association scan. Here the authors report the findings of the stage 1 interim analysis.

Methods

The authors have performed a genome-wide association scan for knee and hip osteoarthritis in 3177 cases and 4894 population-based controls from the UK. Replication of promising signals was carried out in silico in five further scans (44 449 individuals), and de novo in 14 534 independent samples, all of European descent.

Results

None of the association signals the authors identified reach genome-wide levels of statistical significance, therefore stressing the need for corroboration in sample sets of a larger size. Application of analytical approaches to examine the allelic architecture of disease to the stage 1 genome-wide association scan data suggests that osteoarthritis is a highly polygenic disease with multiple risk variants conferring small effects.

Conclusions

Identifying loci conferring susceptibility to osteoarthritis will require large-scale sample sizes and well-defined phenotypes to minimise heterogeneity.

Mitochondrial DNA haplogroups and serum levels of proteolytic enzymes in patients with osteoarthritis

OBJECTIVE

To analyse the influence of mitochondrial DNA haplogroups, as well as the radiographic grade, on serum levels of proteolytic enzymes in patients with osteoarthritis (OA).

METHODS

Serum levels of metalloproteinase-1 (MMP-1), MMP-3, MMP-13, myeloperoxidase and cathepsin K were analysed in 73 patients with OA and 77 healthy controls carrying the haplogroups J, U and H, by ELISA. Knee and hip radiographs were classified according to Kellgren and Lawrence (K/L) scoring from grade 0 to grade IV. Non-parametric and multiple regression analyses were performed to test the effects of clinical variables, including gender, age, smoking status, diagnosis, haplogroups and radiological K/L grade on serum levels of these enzymes.

RESULTS

A significant influence of the haplogroups on the serum levels of MMP-3 and MMP-13 was detected (p=0.027 and p=0.035, respectively). Patients with OA with haplogroup H showed higher serum levels of MMP-3 than healthy controls. Serum levels of MMP-13 were significantly higher in patients with OA (p<0.001), and carriers of the haplogroup J showed lower levels than H carriers. Besides, levels of MMP-13 were proportionally higher in radiological groups B (K/L grade II and III) and C (K/L grade IV) than in group A (K/L grade 0 and I) (p=0.005).

CONCLUSIONS

This study shows that haplogroups have a significant influence on serum levels of MMP-3 and MMP-13. The influence of the haplogroups on serum levels of MMP-3 is clearly dependent on the diagnosis, whereas the influence of the haplogroups on serum levels of MMP-13 is independent of diagnosis.

Design of a composite drug delivery system to prolong functionality of cell-based scaffolds

Cell encapsulation technology raises hopes in medicine and biotechnology. However, despite important advances in the field in the past three decades, several challenges associated with the biocompatibility are still remaining. In the present study, the effect of a temporary release of an anti-inflammatory agent on co-administered encapsulated allogeneic cells was investigated. The aim was to determine the biocompatibility and efficacy of the approach to prevent the inflammatory response. A composite delivery system comprised of alginate-poly-l-lysine-alginate (APA)-microencapsulated Epo-secreting myoblasts and dexamethasone (DXM)-releasing poly(lactic-co-glycolic acid) (PLGA) microspheres was implanted in the subcutaneous space of Balb/c mice for 45 days. The use of independently co-implanted DXM-loaded PLGA microspheres resulted in an improved functionality of the cell-based graft, evidenced by significantly higher hematocrit levels found in the cell-implanted groups by day 45, which was found to be more pronounced when higher cell-doses (100 μL) were employed. Moreover, no major host reaction was observed upon implantation of the systems, showing good biocompatibility and capability to partially avoid the inflammatory response, probably due to the immunosuppressive effects related to DXM. The findings of this study imply that DXM-loaded PLGA microspheres show promise as release systems to enhance biocompatibility and offer advantage in the development of long-lasting and effective implantable microencapsulated cells by generating a potential immunopriviledged local environment and an effective method to limit the structural ensheathing layer caused by inflammation.

Quantification of cells expressing mesenchymal stem cell markers in healthy and osteoarthritic synovial membranes

OBJECTIVE

To quantify cells expressing mesenchymal stem cell (MSC) markers in synovial membranes from human osteoarthritic (OA) and healthy joints.

METHODS

Synovial membranes from OA and healthy joints were digested with collagenase and the isolated cells were cultured. Synovial membrane-derived cells were phenotypically characterized for differentiation experiments using flow cytometry to detect the expression of mesenchymal markers (CD29, CD44, CD73, CD90, CD105, CD117, CD166, and STRO-1) and hematopoietic markers (CD34 and CD45). Chondrogenesis was assessed by staining for proteoglycans and collagen type II, adipogenesis by using a stain for lipids, and osteogenesis by detecting calcium deposits. Coexpression of CD44, CD73, CD90, and CD105 was determined using immunofluorescence.

RESULTS

Cells expressing MSC markers were diffusely distributed in OA synovial membranes; in healthy synovial membrane these cells were localized in the subintimal zone. More numerous MSC markers in OA synovial membranes were observed in cells also expressing the CD90 antigen. FACS analysis showed that more than 90% of OA synovial membrane-derived cells were positive for CD44, CD73, and CD90, and negative for CD34 and CD45. OA synovial membrane-derived cells were also positive for CD29 (85.23%), CD117 (72.35%), CD105 (45.5%), and STRO-1 (49.46%). Micropellet analyses showed that the culture of cells with transforming growth factor-ß3 stimulated proteoglycan and collagen type II synthesis.

CONCLUSION

Synovial membranes from patients with OA contain more cells positive for CD44, CD90, and CD105 antigens than those from joints with undamaged cartilage.

Chondrogenic potential of subpopulations of cells expressing mesenchymal stem cell markers derived from human synovial membranes

In this study we analyzed the chondrogenic potential of subpopulations of mesenchymal stem cells (MSCs) derived from human synovial membranes enriched for CD73, CD106, and CD271 markers. Subpopulations of human synovial membrane MSCs enriched for CD73, CD106, and CD271 markers were isolated using a cytometry sorter and characterized by flow cytometry for MSC markers. The expression of Sox9, Nanog, and Runx2 genes by these cells was measured by reverse transcriptase-polymerase chain reaction. The chondrogenesis of each subpopulation was assessed by culturing the cells in a defined medium to produce spontaneous spheroid formation and differentiation towards chondrocyte-like cells. The examination of the spheroids by histological and immunohistochemical analyses for collagen type II (COL2), aggrecan, collagen type I (COL1), metalloprotease 13 (MMP13), and collagen type X (COLX) levels were performed to assess their chondrogenesis capacity. The adipogenesis and osteogenesis potential of each subpopulation was determined using commercial media; the resulting cells were stained with oil red O or red alizarin to test the degree of differentiation. The subpopulations had different profiles of cells positive for the MSC markers CD44, CD69, CD73, CD90, and CD105 and showed different expression levels of the genes Sox9, Nanog, and Runx2 involved in chondrogenesis, undifferentiation, and osteoblastogenesis, respectively. Immunohistochemical analysis demonstrated that COL1, COL2, COLX, MMP13, and aggrecan were expressed in the spheroids as soon as 14 days of culture. The CD271(+) subpopulation expressed the highest levels of COL2 staining compared to the other subpopulations. CD105 and Runx2 were shown by immunohistochemistry and genetic analysis to have significantly higher expression CD271(+) subpopulation than the other subpopulations. Spheroids formed from CD271-enriched and CD73-enriched MSCs from normal human synovial membranes mimic the native cartilage extracellular matrix more closely than CD106(+) MSCs and are possible candidates for use in cartilage tissue engineering. Both cell types have potential for promoting the differentiation of MSCs into chondrocytes, presenting new possibilities for achieving intrinsic cartilage repair.

Validity of the bath ankylosing spondylitis disease activity index for the evaluation of disease activity in axial psoriatic arthritis

OBJECTIVE

To assess the validity of the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) for the evaluation and definition of disease activity of axial psoriatic arthritis (PsA).

METHODS

Fifty-four peripheral PsA, 46 axial PsA, and 103 primary ankylosing spondylitis (AS) patients were assessed. Patients were classified as having axial PsA if they had grade 2 or higher unilateral sacroiliitis in the presence of spinal symptoms. The 3 groups of patients were evaluated using several measurements for AS. Assessments of acceptability, data quality, internal consistency, construct validity, and responsiveness of the BASDAI were undertaken. Disease activity of the disease was assessed in peripheral PsA and axial PsA patients using the BASDAI, and compared with those with AS.

RESULTS

For peripheral PsA patients, the Cronbach's alpha for the BASDAI was 0.783, for axial PSA patients it was 0.647, and for AS patients it was 0.786. The analysis of convergent validity showed that in peripheral PsA and axial PsA patients, the BASDAI was significantly correlated with other subjective disease activity parameters. For responsiveness, no association was found between changes in the BASDAI and changes in disease activity either in peripheral PsA or in axial PsA. BASDAI scores were similar in axial PsA and AS. Axial PsA patients with a BASDAI score >4 cm showed significant differences with peripheral PsA in terms of disease activity and were very similar to patients with AS.

CONCLUSION

The BASDAI performed similarly in evaluating disease activity in both axial and peripheral PsA. The BASDAI does not seem to be a good index for evaluating disease activity in axial PsA.

Proteomics role in the search for improved diagnosis, prognosis and treatment of osteoarthritis

OBJECTIVE

Osteoarthritis (OA) is the most common rheumatic pathology. It is related to aging and is characterized primarily by cartilage degradation. Despite its high prevalence, the diagnostic methods currently available are limited and lack sensitivity. The focus of this review is the application of proteomic technologies in the search of new biomarkers for improved diagnosis, prognosis and treatment of OA.

METHODS

This review focuses on the utilization of proteomics in OA biomarker research to enable early diagnosis, improved prognosis and the application of tailored treatments.

RESULTS

New diagnostic tests for OA are urgently needed and would also promote the development of alternative therapeutic strategies. Considering that OA involves different tissues and complex biological processes, the most promising diagnostic approach would be the study of combinations of biomarkers. New experimental approaches for the identification and validation of OA biomarkers have recently emerged and include proteomic technologies. These techniques allow the simultaneous analysis of multiple markers and become a very powerful tool for both biomarker discovery and validation.

CONCLUSIONS

Improvements in proteomics technology will undoubtedly lead to advances in characterizing new OA biomarkers and developing alternative therapies. Even so, further work is required to enhance the performance and reproducibility of proteomics tools before they can be routinely used in clinical trials and practice.

Role of European mitochondrial DNA haplogroups in the prevalence of hip osteoarthritis in Galicia, Northern Spain

OBJECTIVE

To analyse the mitochondrial DNA (mtDNA) haplogroups of patients with hip osteoarthritis (OA) and those of healthy controls in a Spanish population.

METHODS

mtDNA haplogroups were assigned to 550 cases of hip OA and 505 clinically asymptomatic controls. Sets of controls with healthy knees and hips (n = 179) and patients with knee and/or hip OA (n = 977) were also analysed in a multivariate analysis after adjusting for sex, age and smoking.

RESULTS

Individuals carrying haplogroup J showed a significantly decreased risk of developing hip OA (OR 0.661; 95% CI 0.440 to 0.993; p = 0.045). In addition to haplogroup J, smoking protected against the development of hip OA (OR 0.543; 95% CI 0.311 to 0.946; p = 0.031). However, no relationship was found between rheumatoid arthritis and mtDNA haplogroups.

CONCLUSION

The results of this study support the hypothesis that the mtDNA haplogroups have a role in the complex osteoarthritic process.

Possible association between NOD2 variants and joint surgery in psoriatic arthritis

BACKGROUND

Psoriatic arthritis (PsA) has been inconsistently associated with common NOD2 gene variants, although some of these studies did not include patient stratification by clinical phenotype.

OBJECTIVES

To analyse the association between the three common NOD2 variants (R702W, G908R and L1007fs) and clinical phenotypes of PsA, particularly with surrogate markers of severe joint destruction.

PATIENTS AND METHODS

A total of 183 unrelated PsA patients and 187 controls were included. Demographic, clinical, biological and immunological characteristics were collected. Genotypes for the three common NOD2 gene variants were obtained by PCR and direct sequencing.

RESULTS

NOD2 variants in PsA patients (7.6%) are just as prevalent as in healthy controls (7.5%). 18.5% of PsA patients carrying at least one NOD2 variant underwent joint surgery compared with 4.5% of those without these variants (p=0.019). Multivariate analysis confirmed this finding (OR 8.82, CI 1.7-46.3). There was no requirement for early surgery in patients carrying the NOD2 variants but there was an increased possibility of requiring surgery at similar times of disease duration. No other association with clinical features and NOD2 status carrier was found.

CONCLUSIONS

Common NOD2 gene variants are not associated with PsA, but might increase the risk of undergoing joint replacement surgery, suggesting that this autoinflammatory-associated gene could act as a phenotypic modifier gene in PsA patients by increasing the risk of joint destruction. Given the small number of PsA patients with joint surgery included, we consider our findings a new hypothesis that will need further testing.

Mitochondrial DNA haplogroups modulate the serum levels of biomarkers in patients with osteoarthritis

OBJECTIVE

To analyse the influence of mitochondrial DNA (mtDNA) haplogroups on serum levels of molecular biomarkers in patients with osteoarthritis (OA).

METHODS

Serum levels of molecular biomarkers of cartilage metabolism (collagen type II markers: C-terminal neoepitope generated by the collagenase-mediated cleavage of collagen type II triple helix (C2C), collagen type II (Coll2-1, and its nitrated form, Coll2-1NO(2)), procollagen type II (CPII)), synovial metabolism (hyaluronic acid (HA)) and cartilage and synovial turnover (cartilage glycoprotein 39 (YKL-40)) were analysed in 73 patients with OA and 77 healthy controls using ELISAs. All participants had been previously genotyped for the mtDNA haplogroups J, U and H. Non-parametric and multivariate analysis were performed to test the effects of the clinical variables, including gender, age, smoking status, diagnosis, mtDNA haplogroups and radiological Kellgren and Lawrence (K/L) grade on the serum levels of the molecular markers.

RESULTS

Non-parametric analysis found increased serum levels of HA in patients with OA, while the values for C2C and the C2C/CPII ratio were significantly higher in the healthy controls. A multiple regression analysis showed a relationship between the mtDNA haplogroups and serum levels of the typical collagen type II markers. Carriers of the mtDNA haplogroup H had higher levels while carriers of the mtDNA haplogroup J showed lower levels. Statistically significant interactions between mtDNA haplogroups and diagnosis and between mtDNA haplogroups and radiological K/L grade in the serum levels of molecular markers were also found.

CONCLUSION

A new role for mtDNA haplogroups emerges from this work. The results suggest that the mtDNA haplogroups interact significantly with the serum levels of OA-related molecular markers, suggesting the possibility of their use as a complementary assay with these molecular markers.

Association of a nsSNP in ADAMTS14 to some osteoarthritis phenotypes

OBJECTIVE

To investigate the effect in OA (Osteoarthritis) susceptibility of putative damaging changes in ADAM (A Disintegrin And Metalloprotease) and ADAMTS (ADAM with ThromboSpondin motif) proteases.

METHODS

Non-synonymous single nucleotide polymorphisms (nsSNP) in 18 ADAMTS and 31 ADAM genes were analyzed with two software applications for prediction of functional damage. Four putative damaging nsSNP were found in ADAMTS2, ADAMTS14, ADAMTS16 and ADAM12, respectively. These nsSNPs were analyzed in case-control sample collections with a variety of phenotypes totalling 3217 OA patients and 2214 healthy controls, all of them Caucasians.

RESULTS

No statistically significant differences were found in ADAMTS2, ADAMTS16 and ADAM12 nsSNPs. Conversely, the rare allele of the rs4747096 nsSNP in ADAMTS14 was overrepresented in women requiring joint replacement because of knee OA (O.R.(M-H) (odds ratio. Mantel-Haenszel)=1.41, 95% C.I.=1.1-1.8; P=0.002) and in patients with symptomatic hand OA (O.R.=1.37, 95% C.I.=1.0-1.9; P=0.047). A non significant increase in the frequency of the same allele was also found in patients with hip OA requiring prosthesis (O.R.(M-H)=1.14, 95% C.I.=1.0-1.3; P=0.08). No association was found with other OA phenotypes.

CONCLUSION

Our findings implicate ADAMTS14 in OA, specifically in knee OA requiring joint replacement in women and, possibly, in hand OA. Independent association of ADAMTS14 genetic variation to knee OA in women has been communicated. ADAMTS14 involvement, if confirmed, will open a new area of interest in OA pathogenesis because of its role in the maturation of collagen fibers.

Anti-apoptotic effect of transforming growth factor-beta1 on human articular chondrocytes: role of protein phosphatase 2A

OBJECTIVE

To study whether transforming growth factor-beta1 (TGF-beta1) is able to protect human chondrocytes from apoptosis and to analyze the role of phosphatases in the possible anti-apoptotic effect of TGF-beta1.

METHODS

Cartilage was obtained from patients with osteoarthritis (OA) who were undergoing joint replacement; normal cartilage was obtained from cadavers who had no history of joint disease. Chondrocytes stimulated with tumor necrosis factor-alpha (TNF-alpha) plus Ro 31-8220 (a specific inhibitor of mitogen-activated kinase phosphatase-1 - MKP-1) were employed as an in vitro model of apoptosis. Apoptosis was assessed by flow cytometry and a cell death immunoassay. Protein phosphatase 2A (PP2A) activity was estimated by measuring the absorbance of a molybdate:malachite green:phosphate reaction complex. MKP-1, bcl-2 and bax expressions were quantified by western blot.

RESULTS

In OA cells, TGF-beta1 significantly reduced the percentage of hypo-diploid chondrocytes, as well as the percentage of internucleosomal DNA breakage. However, in normal chondrocytes, TGF-beta1 did not reduce apoptosis, as assessed by both the percentage of hypo-diploid chondrocytes and internucleosomal DNA breakage. MKP-1 expression did not show significant modulation in OA or normal chondrocytes. However, PP2A activity was differentially modulated in normal and OA chondrocytes. In OA chondrocytes, PP2A activity was not altered by TGF-beta1 stimulation; however in normal chondrocytes PP2A activity was significantly activated by TGF-beta1. The preincubation of normal chondrocytes with TGF-beta1 plus the PP2A inhibitor protein, IPP2A, reduced internucleosomal DNA breakage when compared with TGF-beta1 stimulation alone. The bcl-2/bax protein ratio was significantly higher in TGF-beta1 plus IPP2A preincubated normal chondrocytes than in cells stimulated with TGF-beta1 alone.

CONCLUSION

By manipulating the degree of PP2A activity, these results show the major role that PP2A plays in the outcome of TGF-beta1 signal transduction. These data suggest that PP2A could be a pivotal regulator of anti-apoptotic TGF-beta1-induced effects.

Influence of variants of Fc gamma receptors IIA and IIIA on the American College of Rheumatology and European League Against Rheumatism responses to anti-tumour necrosis factor alpha therapy in rheumatoid arthritis

OBJECTIVE

Fc gamma receptor (Fc gammaR) polymorphism influences the affinity of the receptor for Ig, which may, in turn, affect the efficacy of Ig-based therapies. The relationship between functional single nucleotide polymorphisms (SNP) of the FCGR2A and FCGR3A genes and the response to anti-tumour necrosis factor (TNF)alpha therapy (infliximab) in patients with rheumatoid arthritis (RA) was assessed.

METHODS

A total of 91 patients with RA (89% female; 76.7% rheumatoid factor (RF) positive) starting therapy with infliximab were evaluated at 0, 6 and 30 weeks using the American College of Rheumatology (ACR) and European League Against Rheumatism (EULAR) response criteria and the 28-joint Disease Activity Score (DAS28) was evaluated using three parameters, including C-reactive protein (CRP) (DAS28 3v-CRP) changes during the follow-up. Genotyping of FCGR2A-R131H and FCGR3A-F158V polymorphisms was performed by allele-specific PCR and PCR sequence-based typing, respectively. The chi(2) and Fisher exact tests were used to show differences in the outcome variables, and analysis of variance (ANOVA) to analyse the evolution of DAS28 3v-CRP. A generalised linear models multivariable analysis was also performed.

RESULTS

At week 6 of follow-up, the proportion of patients achieving 50% improvement as per ACR criteria (ACR50) and EULAR good responses were significantly higher among homozygotes of the low affinity FCGR3A allele (FF: 24.1% and VV-VF:2.2%; p = 0.003 and FF: 44.8% and VV-VF: 22.9%; p = 0.040, respectively). At week 30, homozygotes of the low affinity FCGR2A allele had a better ACR20 response (RR: 60% and HH-RH: 33.3%; p = 0.035). Changes in DAS28 3v-CRP during follow-up were consistent with those observed in ACR and EULAR responses.

CONCLUSIONS

The response to anti-TNFalpha treatment with infliximab in patients with RA is influenced by the FCGR2A and FCGR3A genotypes. This effect is observed at different times in the follow-up (6 and 30 weeks, respectively) indicating the dynamic nature of the Fc gammaR versus Ig interaction.

Differential effects of tumor necrosis factor-alpha and interleukin-1beta on cell death in human articular chondrocytes

OBJECTIVE

The death of chondrocytes by apoptosis is characteristic of degenerative joint diseases, such as osteoarthritis (OA). Tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) have been shown to play an important role in the development of OA. In this study we analyzed the effects of TNF-alpha and IL-1beta on cell death in normal human chondrocytes.

METHODS

Normal human chondrocytes were isolated from knee cartilage obtained at autopsy from 30 adult cadaveric donors. The cells were stimulated with TNF-alpha (10 ng/ml) or IL-1beta (5 ng/ml) in the presence or absence of Ro 31-8220 (Ro: a structurally related analog of bisindolylmaleimide that inhibits mitogen-activated protein kinase phosphatase 1 [MKP-1]) (Ro; 10 microM), an MKP-1 inhibitor, which induces apoptosis in chondrocytes. Apoptosis was evaluated by flow cytometry (propidium iodide) and nuclear morphology was evaluated with 4',6'-dianidino-2-phenylindole dihydrochloride. The expressions of caspase-8, -7 and -3 and Bcl-2 were analyzed by Western blot and the activation of caspase-3 and -8 was measured by flow cytometry. Prostaglandin E2 (PGE2) was evaluated by enzyme-linked immunosorbent assay.

RESULTS

At 24 h the percentage of apoptotic (hypodiploid) nuclei induced by TNF-alpha+Ro was higher than the level induced by Ro alone. The combination of IL-1beta (5 ng/ml) with Ro did not show a synergistic effect. A morphological analysis demonstrated that treatment with TNF-alpha+Ro resulted in a large number of cells with condensed nuclei and DNA fragmentation. Western blot studies indicated that IL-1beta+Ro did not induce the time-dependent activation of caspase-8, -7 and -3 as seen with TNF-alpha+Ro. As quantified by flow cytometry, TNF-alpha+Ro induced a higher level of caspase-3 and -8 activation than that seen with IL-1beta+Ro. Pre-incubation for 2h with caspase inhibitors for caspase-3, -7, -8 and pan-caspase significantly decreased the hypodiploid DNA peak induced by treatment with TNF-alpha+Ro at 24 h. Indomethacin increased the cell death induced by IL-1beta+Ro; however, apoptosis induced by TNF-alpha+Ro was not modified by indomethacin.

CONCLUSIONS

These results confirm that TNF-alpha and IL-1beta regulate apoptosis differently in this human chondrocyte model and that the differing effects of these cytokines are PGE2-independent. Indomethacin potentiates the effect of IL-1 on cell death and this may explain the reported effect of indomethacin on the progression of joint destruction.