Down‐regulation of FLIP sensitizes rheumatoid synovial fibroblasts to Fas‐mediated apoptosis

Objective

Hyperplasia of fibroblast‐like synoviocytes (FLS) contributes to chronic inflammation and joint destruction in rheumatoid arthritis (RA). FLICE‐inhibitory protein (FLIP) is an antiapoptotic protein that might prevent apoptotic elimination of FLS in response to death ligands such as tumor necrosis factor α (TNFα) or Fas ligand, which are present in RA synovium. Previous studies on FLIP expression by osteoarthritis (OA) and RA FLS have shown variable results, and the specific role of FLIP as an apoptosis inhibitor in these cells remains unclear. We undertook this study to investigate the expression and antiapoptotic function of FLIP in FLS.

Methods

We studied the expression of FLIP by immunohistochemistry and immunoblotting in synovial tissues or cultured FLS from RA and OA patients. FLS apoptosis was induced by an agonistic anti‐Fas monoclonal antibody and FLS were then quantified. We studied the effects of cycloheximide (CHX), TNFα, and FLIP antisense oligonucleotide on FLIP expression and FLS apoptotic susceptibility.

Results

FLIP_L was the isoform mainly expressed in lining synoviocytes and cultured FLS. Synovial tissues and cultured FLS from OA and RA tissues displayed similar patterns and levels of expression of FLIP. Fas‐induced apoptosis was variable in different FLS lines, but differences between OA and RA groups were not detected. TNFα induced increases in FLIP_L and FLIP_S expression and protected RA FLS from apoptosis, while CHX induced the opposite effects. Down‐regulation of FLIP by antisense oligonucleotide strongly sensitized RA FLS to Fas‐mediated apoptosis.

Conclusion

Apoptosis susceptibility and FLIP expression are similar in OA and RA FLS. Down‐regulation of FLIP sensitizes RA FLS to Fas‐mediated apoptosis and may be a valuable tool for targeting RA FLS hyperplasia.

     

PUMA regulation and proapoptotic effects in fibroblast‐like synoviocytes

Objective

Although p53 is overexpressed in rheumatoid arthritis (RA) synovial tissue (ST), few synoviocytes undergo apoptosis. This could be partly due to low expression of proapoptotic genes. Deficient p53 up‐regulated modulator of apoptosis (PUMA), which is a major effector of p53‐mediated cell death, could contribute to this phenomenon. To evaluate a method to induce apoptosis, the expression and function of PUMA was investigated in ST and cultured fibroblast‐like synoviocytes (FLS).

Methods

PUMA expression in ST was measured by immunohistochemistry, Western blot analysis, and quantitative polymerase chain reaction analysis. Ad‐p53 and plasmids encoding hemagglutinin‐tagged, full‐length PUMA expression vector (HA‐PUMA), PUMA lacking the Bcl‐2 homology 3 domain, or pCEP4 were used to transfect FLS. Apoptosis was quantified by trypan blue exclusion, DNA fragmentation, and caspase 3 activation.

Results

PUMA protein was detected in RA ST, although most of the immunoreactive protein was localized to sublining cells rather than the intimal lining synoviocytes. Western blot analysis showed no difference between RA ST and osteoarthritis (OA) ST. PUMA messenger RNA was detected in RA and OA ST, although the amounts were markedly lower than in the spleen and FLS. To determine if PUMA was inducible, FLS were transduced with Ad‐p53. Even though p53 protein was produced and p21 expression was increased, PUMA expression was not enhanced. Consistent with this observation, Ad‐p53 did not induce apoptosis in FLS. However, HA‐PUMA transfection into FLS resulted in rapid apoptosis with the activation of caspase 3.

Conclusion

PUMA can induce apoptosis by FLS and represents a potential target in RA.

     

Control of fibroblast‐like synoviocyte proliferation by macrophage migration inhibitory factor

Objective

The hyperplasia of fibroblast‐like synoviocytes (FLS) is considered essential to the evolution of joint destruction in rheumatoid arthritis (RA), but the mechanisms underlying FLS proliferation remain poorly understood. Macrophage migration inhibitory factor (MIF) is a cytokine that has recently been shown to exert proinflammatory effects on RA FLS. This study sought to identify the mechanisms of activation of FLS by MIF, and to assess the effects of MIF on synovial cell proliferation.

Methods

Human RA FLS were treated with recombinant MIF, interleukin‐1β (IL‐1β), tumor necrosis factor α (TNFα), and/or anti‐MIF monoclonal antibodies (mAb). Proliferation was measured with tritiated thymidine incorporation. Nuclear factor κB (NF‐κB) and mitogen‐activated protein (MAP) kinase activation were measured with immunohistochemistry and Western blotting, respectively.

Results

FLS proliferation was significantly increased by MIF. IL‐1β and TNFα also induced proliferation, but these effects were prevented by neutralization with anti‐MIF mAb. Activation of NF‐κB was induced by IL‐1β, but not by MIF. Anti‐MIF mAb had no effect on IL‐1β–induced NF‐κB nuclear translocation. By contrast, MIF induced phosphorylation of extracellular signal–regulated kinase (ERK) MAP kinase. ERK antagonism, but not NF‐κB antagonism, prevented the effect of MIF on FLS proliferation.

Conclusion

These data suggest that MIF may regulate RA synovial hyperplasia by acting directly and via involvement in the effects of IL‐1β and TNFα. In addition, the effects of MIF on FLS activation are independent of NF‐κB, and dependent on ERK MAP kinase. These data suggest an important therapeutic potential for MIF antagonism in RA.

     

Anti–interleukin‐6 receptor antibody therapy reduces vascular endothelial growth factor production in rheumatoid arthritis

Objective

To investigate whether interleukin‐6 (IL‐6) is a regulator of vascular endothelial growth factor (VEGF) in rheumatoid arthritis (RA).

Methods

Serum VEGF levels in RA patients were assayed before and after 8 weeks or 24 weeks of maintenance therapy with humanized anti–IL‐6 receptor monoclonal antibody (anti–IL‐6R mAb). VEGF secreted by RA synovial fibroblasts cultured in the presence of IL‐6, IL‐1β, and/or tumor necrosis factor α (TNFα) was measured. The inhibitory effect of anti–IL‐6R mAb, recombinant IL‐1 receptor antagonist (IL‐1Ra), and anti‐TNFα mAb on VEGF production was also examined.

Results

Serum VEGF levels in RA patients before anti–IL‐6R mAb therapy were significantly higher than those in healthy controls (P < 0.0005). Treatment of RA patients with anti–IL‐6R mAb normalized serum VEGF levels. In the in vitro study, IL‐6 and IL‐1β each induced a slight amount of VEGF production in synovial cells, but TNFα did not. Although VEGF‐inducing activity of these cytokines was not remarkable when they were added alone, IL‐6 acted synergistically with IL‐1β or TNFα to induce VEGF production. There was no synergistic effect between IL‐1β and TNFα. In the presence of all of these cytokines, anti–IL‐6R mAb eliminated the synergistic effect of IL‐6, IL‐1β, and TNFα, while IL‐1Ra or anti‐TNFα mAb did not.

Conclusion

Anti–IL‐6R mAb therapy reduced VEGF production in RA. IL‐6 is the pivotal cytokine that induces VEGF production in synergy with IL‐1β or TNFα, and this may be the mechanism by which IL‐6 blockade effectively suppresses VEGF production in synovial fibroblasts.

     

Splenocyte apoptosis in Plasmodium berghei ANKA infection: possible role of TNF‐α and TGF‐β

Cerebral malaria is associated with the circulating levels of tumour necrosis factor alpha (TNF‐α) and transforming growth factor β (TGF‐β), but association between these two cytokines and implications in splenocyte apoptosis remain largely obscured. We have evaluated the outcome of TGF‐β and TNF‐α production in the context of splenocyte apoptosis during Plasmodium berghei ANKA (PbA) infection. Blood‐stage PbA infection confirmed blood–brain barrier disruption, disarray of white pulp, increase in percentage of sub‐G0/G1 and splenocyte apoptosis. Flow cytometric analysis reveals up‐regulation of Fas‐L followed by caspase‐8 and caspase‐3 activation and signifies possible involvement of Fas‐L‐mediated splenocyte apoptosis. We have observed down‐regulation of TGF‐β and up‐regulation of TNF‐α in tissue and serum level, respectively, during PbA infection. Association between the production of TGF‐β and the severity of malaria infection in splenocytes was verified with TGF‐β inhibitor that exacerbated the apoptotic process. In contrary, TNF‐α inhibitor causes significant delay in apoptotic process, but could not alter the lethality of parasite. Thus, results from this study suggest that the critical balance between TGF‐β and TNF‐α might have a key role on Fas‐L‐mediated splenocyte apoptosis during experimental cerebral malaria.     

Rheumatoid arthritis synovial macrophages express the Fas‐associated death domain–like interleukin‐1β–converting enzyme–inhibitory protein and are refractory to Fas‐mediated apoptosis

Objective

The chronic inflammation and progressive joint destruction observed in rheumatoid arthritis (RA) are mediated in part by macrophages. A paucity of apoptosis has been observed in RA synovial tissues, yet the mechanism remains unknown. The present study sought to characterize the expression of Fas, Fas ligand (FasL), and Fas‐associated death domain–like interleukin‐1β–converting enzyme–inhibitory protein (FLIP), and to quantify the apoptosis induced by agonistic anti‐Fas antibody, using mononuclear cells (MNC) isolated from the peripheral blood (PB) and synovial fluid (SF) of RA patients.

Methods

The expression of Fas, FasL, and FLIP and apoptosis induced by agonistic anti‐Fas antibody in MNC from the PB and SF of RA patients were determined by flow cytometry. Immunohistochemistry employing a monospecific anti‐FLIP antibody was performed on RA and osteoarthritis (OA) synovial tissue.

Results

CD14‐positive monocyte/macrophages from normal and RA PB and from RA SF expressed equivalent levels of Fas and FasL. Furthermore, unlike the CD14‐positive PB monocytes, RA SF monocyte/macrophages were resistant to the addition of agonistic anti‐Fas antibody. In contrast, both CD14‐positive PB and SF monocyte/macrophages were sensitive to apoptosis mediated by a phosphatidylinositol 3‐kinase inhibitor. Intracellular staining of the caspase 8 inhibitor, FLIP, in CD14‐positive SF monocyte/macrophages revealed a significant up‐regulation of FLIP compared with normal and RA PB monocytes. Immunohistochemical analysis of synovial tissue from RA and OA patients revealed increased FLIP expression in the RA synovial lining compared with the OA synovial lining. Furthermore, FLIP expression was observed in the CD68‐positive population in the RA synovial lining. Forced reduction of FLIP by a chemical inhibitor resulted in RA SF macrophage apoptosis that was enhanced by agonistic anti‐Fas antibody, indicating that FLIP is necessary for SF macrophage survival.

Conclusion

These data suggest that up‐regulation of FLIP in RA macrophages may account for their persistence in the disease. Thus, the targeted suppression of FLIP may be a potential therapeutic strategy for the amelioration of RA.

     

Rheumatoid arthritis synovial fluid fibroblasts express TRAIL‐R2 (DR5) that is functionally active

Objective

To examine fibroblasts grown from the synovial fluid of rheumatoid arthritis (RA) patients for TRAIL‐R2 expression, and for susceptibility to apoptosis induced by an agonistic anti–TRAIL‐R2 monoclonal antibody (mAb).

Methods

The expression of TRAIL‐R2 (DR5) was determined by flow cytometry on fibroblasts grown from the synovial fluid of patients with RA, osteoarthritis (OA), seronegative arthritis, and unclassified monarthritis or oligoarthritis, and on fibroblasts from the synovial membrane of RA and OA patients. Susceptibility to apoptosis mediated by an agonistic anti–TRAIL‐R2 mAb was determined by alamar blue bioassay, fluorescence microscopy (annexin V/propidium iodide staining), and caspase activation.

Results

Fibroblasts grew from 35 of 50 RA synovial fluid samples, of which 26 were DR5+ (mean [±SD] fluorescence intensity [MFI] 18.74 ± 2.5). Fibroblasts also grew from 15 of 30 seronegative arthritis synovial fluid samples, 28 of 40 OA synovial fluid samples, and 8 of 20 unclassified monarthritis or oligoarthritis synovial fluid samples; all of these were DR5− (MFI 0.32 ± 0.02). All 10 of the fibroblast lines from joint replacement surgery or synovectomy specimens of RA patients were DR5+ (MFI 20.3 ± 3.2). All fibroblast lines from the synovium of 10 OA patients were DR5−, as were fibroblasts from the skin of 5 healthy subjects. DR5+ fibroblast cultures underwent apoptosis when treated in vitro with an agonistic anti‐DR5 antibody.

Conclusion

Fibroblasts grown from the synovial fluid and synovial membrane of RA patients express TRAIL‐R2 that is functionally active. An agonistic anti–TRAIL‐R2 antibody that does not induce hepatocyte toxicity may be an alternative strategy for treatment of RA.

     

Effectiveness of anti–folate receptor β antibody conjugated with truncated Pseudomonas exotoxin in the targeting of rheumatoid arthritis synovial macrophages

Objective

To define the distribution of folate receptor β (FRβ)–expressing cells in various tissues, including rheumatoid arthritis (RA) synovial tissues, and to verify the effects of an immunotoxin composed of an anti‐FRβ monoclonal antibody (mAb) and truncated Pseudomonas exotoxin A (PEA) on apoptosis and tumor necrosis factor α (TNFα) production by adherent synovial mononuclear cells from RA patients.

Methods

Anti‐FRβ mAb were produced by immunizing mice with FRβ‐transfected murine pre–B cells. The distribution of the FRβ antigen was examined by immunohistochemical analysis using anti‐FRβ mAb and macrophage‐specific anti‐CD163 mAb. Anti‐FRβ mAb was chemically crosslinked with truncated PEA. FRβ‐expressing macrophages were produced by the transfection of adenovirus vector containing the FRβ gene. Apoptotic cells were detected by staining with propidium iodide. TNFα was measured by enzyme‐linked immunosorbent assay.

Results

FRβ‐expressing cells were not present in peripheral blood leukocytes and their activated cells. In all of the tissues examined, most FRβ‐expressing cells were CD163+. The immunotoxin significantly induced the apoptosis of FRβ‐transfected macrophages and adherent RA synovial mononuclear cells and inhibited TNFα production by adherent RA synovial mononuclear cells.

Conclusion

We demonstrated the limited distribution of FRβ‐expressing cells in various tissues. The immunotoxin targeting FRβ‐expressing cells will provide a therapeutic tool for rheumatoid synovitis.

     

The use of anti‐tumour necrosis factor‐α therapies for rheumatoid arthritis in Singapore

Anti‐tumour necrosis factor‐α (anti‐TNF‐α) agents are biologic disease‐modifying antirheumatic drugs (DMARDs) used in the treatment of moderate to severe rheumatoid arthritis (RA). We describe the demographic and therapeutic profiles of 22 patients who received anti‐TNF‐α therapy for RA in two hospitals in Singapore. The majority of patients were female, middle‐aged, full‐time working adults with limitation in their social or vocational activities. The mean RA disease duration was 101.4 ± 101.6 months (3.4–401.3). All received conventional DMARDs for a mean of almost 7 years before starting anti‐TNF‐α, with the majority having failed two or more DMARDs. The most commonly used anti‐TNF‐α therapies were infliximab (90.9%), etanercept (18.2%) and adalimumab (4.5%). Only one patient developed a major infection, while three developed minor infections requiring temporary cessation of anti‐TNF‐α therapy. There were no cases of malignancy, drug‐induced lupus, demyelinating disease or congestive heart failure during an average of 36.9 ± 21.9 months (3.9–63.0) from initiation of therapy.     

Down‐regulation of myeloid cell leukemia 1 by epigallocatechin‐3‐gallate sensitizes rheumatoid arthritis synovial fibroblasts to tumor necrosis factor α–induced apoptosis

Objective

Overexpression of the antiapoptotic protein myeloid cell leukemia 1 (Mcl‐1) in rheumatoid arthritis (RA) synovial fibroblasts is a major cause of their resistance to tumor necrosis factor α (TNFα)–induced apoptosis. This study was undertaken to evaluate the efficacy of epigallocatechin‐3‐gallate (EGCG) in down‐regulating Mcl‐1 expression and its mechanism of RA synovial fibroblast sensitization to TNFα‐induced apoptosis.

Methods

EGCG effects on cultured RA synovial fibroblast cell morphology, proliferation, and viability over 72 hours were determined by microscopy and a fluorescent cell enumeration assay. Caspase 3 activity was determined by a colorimetric assay. Western blotting was used to evaluate the apoptosis mediators poly(ADP‐ribose) polymerase (PARP), Mcl‐1, Bcl‐2, Akt, and nuclear translocation of NF‐κB.

Results

In RA synovial fibroblasts, EGCG (5–50 μM) inhibited constitutive and TNFα‐induced Mcl‐1 protein expression in a concentration‐ and time‐dependent manner (P < 0.05). Importantly, EGCG specifically abrogated Mcl‐1 expression in RA synovial fibroblasts and affected Mcl‐1 expression to a lesser extent in osteoarthritis and normal synovial fibroblasts or endothelial cells. Inhibition of Mcl‐1 by EGCG triggered caspase 3 activity in RA synovial fibroblasts, which was mediated via down‐regulation of the TNFα‐induced Akt and NF‐κB pathways. Caspase 3 activation by EGCG also suppressed RA synovial fibroblast growth, and this effect was mimicked by Akt and NF‐κB inhibitors. Interestingly, Mcl‐1 degradation by EGCG sensitized RA synovial fibroblasts to TNFα‐induced PARP cleavage and apoptotic cell death.

Conclusion

Our findings indicate that EGCG itself induces apoptosis and further sensitizes RA synovial fibroblasts to TNFα‐induced apoptosis by specifically blocking Mcl‐1 expression and, hence, may be of promising adjunct therapeutic value in regulating the invasive growth of synovial fibroblasts in RA.

     

Lysophosphatidic acid receptor 1 suppression sensitizes rheumatoid fibroblast‐like synoviocytes to tumor necrosis factor–induced apoptosis

Objective

To investigate the role of lysophosphatidic acid (LPA) receptors in the proliferation and apoptosis of fibroblast‐like synoviocytes (FLS) from patients with rheumatoid arthritis (RA).

Methods

Expression of LPA receptors 1–3 was analyzed by real‐time polymerase chain reaction (PCR). LPAR1 and LPAR2 were suppressed in RA FLS by small interfering RNA (siRNA) transfection. Proliferation of RA FLS after tumor necrosis factor (TNF) and LPA stimulation was determined with a luminescent cell viability assay. Apoptosis was analyzed by quantification of nucleosome release and measurement of activated caspase 3/7. Genes involved in the apoptotic response were identified with a human apoptosis PCR array and validated with Western blot assays. The requirement of these genes for apoptosis sensitization was assessed by siRNA transfection. Secretion of mediators of inflammation was analyzed by enzyme‐linked immunosorbent assay.

Results

Only LPAR1 and LPAR2 were expressed by RA FLS, and their levels were higher than those in osteoarthritis (OA) FLS. Suppression of LPAR1 abrogated TNF‐induced proliferation and sensitized the RA FLS, but not the OA FLS, to TNF‐induced apoptosis. These changes occurred despite an increased early inflammatory response to TNF. Sensitization to apoptosis was associated with changes in expression of multiple apoptosis‐related genes. Three of the up‐regulated proapoptotic genes were further studied to confirm their involvement. In contrast, suppression of LPAR2 showed no effect in any of these analyses.

Conclusion

LPA₁ is an important receptor in RA FLS. Its suppression is accompanied by a global increase in the response to TNF that is ultimately dominated by sensitization to apoptosis.

     

Melatonin attenuates TNF‐α and IL‐1β expression in synovial fibroblasts and diminishes cartilage degradation: Implications for the treatment of rheumatoid arthritis

The hormone melatonin has many properties, including antioxidant, anti‐inflammatory, and immunomodulatory effects. Melatonin has been demonstrated to be beneficial in several inflammatory autoimmune diseases, but its effects in rheumatoid arthritis (RA) remain controversial. We sought to determine how melatonin regulates inflammation in RA. We found that melatonin dose‐dependently inhibits tumor necrosis factor‐α (TNF‐α) and interleukin (IL)‐1β expression through the PI3K/AKT, ERK, and NF‐κB signaling pathways. We also identified that melatonin inhibits TNF‐α and IL‐1β production by upregulating miR‐3150a‐3p expression. Synovial tissue specimens from RA patients and culture of human rheumatoid fibroblast‐like synoviocytes confirmed that the MT1 receptor is needed for the anti‐inflammatory activities of melatonin. Importantly, melatonin also significantly reduced paw swelling, cartilage degradation, and bone erosion in the collagen‐induced arthritis mouse model. Our results indicate that melatonin ameliorates RA by inhibiting TNF‐α and IL‐1β production through downregulation of the PI3K/AKT, ERK, NF‐κB signaling pathways, as well as miR‐3150a‐3p overexpression. The role of melatonin as an adjuvant treatment in patients with RA deserves further clinical studies.     

The small ubiquitin‐like modifier mediates the resistance of prosthesis‐loosening fibroblast‐like synoviocytes against fas‐induced apoptosis

Objective

To study the expression of small ubiquitin‐like modifier 1 (SUMO‐1) in aseptic loosening of prosthesis implants and to investigate its role in regulating the susceptibility of prosthesis‐loosening fibroblast‐like synoviocytes (FLS) to Fas‐induced apoptosis.

Methods

Specimens of aseptically loosened tissue were obtained at revision surgery, and the expression of SUMO‐1 was analyzed by in situ hybridization. SUMO‐1 levels in FLS were determined by quantitative polymerase chain reaction and Western blot analysis. Immunohistochemistry and confocal microscopy were used to study the subcellular localization of SUMO‐1. The functional role of SUMO‐1 in Fas‐induced apoptosis of prosthesis‐loosening FLS was investigated by small interfering RNA–mediated knockdown of SUMO‐1 and by gene transfer of the nuclear SUMO‐specific protease SENP1.

Results

SUMO‐1 was expressed strongly in aseptically loosened tissue and was found prominently at sites adjacent to bone. Prosthesis‐loosening FLS expressed levels of SUMO‐1 similar to the levels expressed by rheumatoid arthritis (RA) FLS, with SUMO‐1 being found mainly in promyelocytic leukemia protein nuclear bodies. Knockdown of SUMO‐1 had no effect on spontaneous apoptosis but significantly increased the susceptibility of prosthesis‐loosening FLS to Fas‐induced apoptosis. Gene transfer of the nuclear SUMO‐specific protease SENP1 reverted the apoptosis‐inhibiting effects of SUMO‐1.

Conclusion

These data suggest that SUMO‐1 is involved in the activation of both RA FLS and prosthesis‐loosening FLS by preventing these cells from undergoing apoptosis. Modification of nuclear proteins by SUMO‐1 contributes to the antiapoptotic effects of SUMO‐1 in prosthesis‐loosening FLS, providing evidence for the specific activation of sumoylation during their differentiation. Therefore, SUMO‐1 may be an interesting target for novel strategies to prevent aseptic prosthesis loosening.

     

The inhibition of TNF‐α‐induced leucocyte apoptosis by melatonin involves membrane receptor MT1/MT2 interaction

The pro‐apoptotic signalling cascades induced by tumour necrosis factor‐alpha (TNF‐α) have been intensively studied in multiple cellular systems. So far, it is known that TNF‐α can simultaneously activate survival and apoptotic cell death responses. The balance between these signals determines the ultimate response of the cell to TNF‐α. Moreover, emerging evidence suggests that melatonin may be involved in the protection of different cell types against apoptosis. Thus, the objective of this study was to evaluate the effect of melatonin on TNF‐α‐induced apoptosis in human leucocytes. Cells were treated with TNF‐α alone or in the presence of cycloheximide (CHX), which promotes caspase‐8 activation by eliminating the endogenous caspase‐8 inhibitor, c‐FLIP. Treatment with TNF‐α/CHX led to apoptotic cell death, as ascertained by annexin V/propidium iodide (PI) staining. Likewise, in the presence of CHX, TNF‐α stimulation produced cFLIP down‐regulation and subsequent caspase‐8 activation, thus directly triggering caspase‐3 activation and causing Bid truncation and subsequent caspase‐9 activation. Conversely, pre‐incubation of cells with melatonin inhibited TNF‐α‐/CHX‐evoked leucocyte apoptosis. Similarly, pretreatment of leucocytes with melatonin increased cFLIP protein levels, thereby preventing TNF‐α‐/CHX‐mediated caspase processing. Blockade of melatonin membrane receptor MT1/MT2 or extracellular signal‐regulated kinase (ERK) pathway with luzindole or PD98059, respectively, abolished the inhibitory effects of melatonin on leucocyte apoptosis evoked by TNF‐α/CHX. In conclusion, the model proposed by these findings is that the MT1/MT2 receptors, which are under the positive control of melatonin, trigger an ERK‐dependent signalling cascade that interferes with the anti‐apoptotic protein cFLIP modulating the cell life/death balance of human leucocytes.     

NF‐κB–regulated expression of cellular FLIP protects rheumatoid arthritis synovial fibroblasts from tumor necrosis factor α–mediated apoptosis

Objective

Little apoptosis has been observed in rheumatoid arthritis (RA) synovial tissues. Tumor necrosis factor α (TNFα) is expressed in the joints of patients with RA, yet RA synovial fibroblasts are relatively resistant to apoptosis induced by TNFα. Recently, we demonstrated that FLIP is highly expressed in the RA joint. These studies were performed to determine if TNFα‐induced NF‐κB controls the expression of FLIP long (FLIP_L) and FLIP short (FLIP_S) in RA synovial fibroblasts and to determine the role of FLIP in the control of TNFα‐induced apoptosis.

Methods

RA synovial fibroblasts were isolated from RA synovial tissues and used between passages 3 and 9. RA synovial or control fibroblasts were sham infected or infected with a control adenovirus vector or one expressing the super‐repressor IκBα (srIκBα). The cells were stimulated with TNFα or a control vehicle, and expression of FLIP_L and FLIP_S was determined by isoform‐specific real‐time polymerase chain reaction and Western blot analysis. Cell viability was determined by XTT cleavage, and apoptosis was determined by annexin V staining, DNA fragmentation, and activation of caspases 8 and 3.

Results

TNFα induced the expression of both isoforms of FLIP messenger RNA (mRNA) in RA synovial fibroblasts; however, FLIP_L was the dominant isoform detected by Western blot analysis. In control fibroblasts, TNFα induced the expression of FLIP_L and FLIP_S mRNA and protein. The TNFα‐induced, but not the basal, expression of FLIP was regulated by NF‐κB. When NF‐κB activation was suppressed by the expression of srIκBα, TNFα‐mediated apoptosis was induced. TNFα‐induced apoptotic cell death was mediated by caspase 8 activation and was prevented by the ectopic expression of FLIP_L or the caspase 8 inhibitor CrmA.

Conclusion

The TNFα‐induced, but not the basal, expression of FLIP is regulated by NF‐κB in RA synovial fibroblasts. The resistance of RA synovial fibroblasts to TNFα‐induced apoptosis is mediated by the NF‐κB–regulated expression of FLIP. These observations support the role of NF‐κB and FLIP as attractive therapeutic targets in RA.

     

PUMA regulation and proapoptotic effects in fibroblast-like synoviocytes

OBJECTIVE: Although p53 is overexpressed in rheumatoid arthritis (RA) synovial tissue (ST), few synoviocytes undergo apoptosis. This could be partly due to low expression of proapoptotic genes. Deficient p53 up-regulated modulator of apoptosis (PUMA), which is a major effector of p53-mediated cell death, could contribute to this phenomenon. To evaluate a method to induce apoptosis, the expression and function of PUMA was investigated in ST and cultured fibroblast-like synoviocytes (FLS). METHODS: PUMA expression in ST was measured by immunohistochemistry, Western blot analysis, and quantitative polymerase chain reaction analysis. Ad-p53 and plasmids encoding hemagglutinin-tagged, full-length PUMA expression vector (HA-PUMA), PUMA lacking the Bcl-2 homology 3 domain, or pCEP4 were used to transfect FLS. Apoptosis was quantified by trypan blue exclusion, DNA fragmentation, and caspase 3 activation. RESULTS: PUMA protein was detected in RA ST, although most of the immunoreactive protein was localized to sublining cells rather than the intimal lining synoviocytes. Western blot analysis showed no difference between RA ST and osteoarthritis (OA) ST. PUMA messenger RNA was detected in RA and OA ST, although the amounts were markedly lower than in the spleen and FLS. To determine if PUMA was inducible, FLS were transduced with Ad-p53. Even though p53 protein was produced and p21 expression was increased, PUMA expression was not enhanced. Consistent with this observation, Ad-p53 did not induce apoptosis in FLS. However, HA-PUMA transfection into FLS resulted in rapid apoptosis with the activation of caspase 3. CONCLUSION: PUMA can induce apoptosis by FLS and represents a potential target in RA.     

Novel agents in the future: Therapy beyond anti‐TNF agents in inflammatory bowel disease

Anti‐tumor necrosis factor (TNF)‐α agents emerge as the hot spot in the last decade for treating patients with inflammatory bowel disease (IBD). The effect of anti‐TNF‐α agents is satisfactory; however, some patients fail to achieve clinical response. Fortunately, in recent years, great efforts have been made and multiple novel therapies have been developed in the treatment for IBD. In this article, we aim to introduce anti‐TNF‐α drugs as well as other novel treatments currently undergoing clinical trials for IBD.     

‘It's magic stuff’: The experiences of patients with ankylosing spondylitis taking anti‐TNF‐α medication

Introduction: Several studies have identified the efficacy of anti‐tumour necrosis factor‐alpha (anti‐TNF‐α) treatment in ankylosing spondylitis (AS). However, few studies have explored the perceptions of patients taking this new medication. The aim of this study was to explore the impact of anti‐TNF‐α on the quality of life of people with AS. Methods: A qualitative approach was adopted to provide a holistic understanding of participants' views and experiences in the context of their overall lives. Semi‐structured interviews were undertaken and transcribed verbatim. Data were analysed using thematic analysis. Ethical approval and informed consent were obtained. Results: Eight people participated and described a significant improvement in their physical and psychological status, leading to a more positive outlook on their life. Specific areas highlighted were employment, activities of daily living, hobbies and relationships with partners and family, some of which are not captured by current AS‐specific outcome measures. Negative aspects of anti‐TNF‐α use were described as the inconvenience of monitoring and issues relating to travelling abroad. All participants expressed concern about the possibility of being withdrawn from treatment and the perceived impact this would have on their lives. Conclusions: Anti‐TNF‐α treatment has a positive impact on the lives of people with AS, such that a major concern is being withdrawn from treatment, highlighting the need to provide tailored support to people being withdrawn from treatment. To capture the full impact of anti‐TNF‐α treatment, further consideration needs to be given to the choice of appropriate outcome measures. Copyright © 2008 John Wiley & Sons, Ltd.