Systemic sclerosis: changes in the incidence rates in the Finnish population during the years 1999-2018.

OBJECTIVE: The aim of our study was to examine changes in the incidence of systemic sclerosis (SSc) in Finland using two different classification criteria. METHOD: Medical records of patients who had been registered with ICD-10 code M34 from 1999 to 2018 in two university hospitals were reviewed retrospectively. This period was divided into 5 year periods: 1999-2003, 2004-2008, 2009-2013, and 2014-2018. Using American College of Rheumatology (ACR)/European League Against Rheumatism (EULAR) 2013 criteria and clinical findings, we reclassified patients into four groups: diffuse SSc, limited SSc, sine SSc, or early SSc. In the same population, we also investigated whether the ACR 1980 criteria were fulfilled. RESULTS: In 1999-2018, 246 new patients with SSc and 45 patients with early SSc were identified using ACR/EULAR 2013 criteria. Of these patients, 70 fulfilled the ACR 1980 criteria. Using ACR/EULAR 2013 criteria, the increase in new diagnoses was statistically significant when comparing the fourth period with the first period (p = 0.0012). The increase was due to a rise in limited SSc. Mean annual incidence rates in these groups were 0.9, 1.2, 1.9, and 2.8 per 100 000 inhabitants ≥ 16 years old. An increasing trend was also seen when using ACR 1980 criteria, but this was not statistically significant. CONCLUSION: The incidence of SSc increased during the period between 1999-2003 and 2014-2018 using ACR/EULAR 2013, but not using ACR 1980 criteria. The increase was detected within a limited SSc subclass, owing to more sensitive classification criteria.

Causes and predictors of death among Finnish patients with systemic sclerosis.

OBJECTIVE: The aim of this study was to assess causes and predictors of death among Finnish patients with systemic sclerosis (SSc). METHOD: Medical records of patients registered with the ICD-10 code M34 from 1996 to 2018 in two university hospitals were reviewed retrospectively. Clinical data were collected until the end of 2020. Death certificates were obtained from Statistics Finland up to August 2021. Using death certificates and patient records, the cause of death for each patient was determined. The mean age at death, median time from SSc diagnosis, and factors predicting death were analysed. RESULTS: Among 313 SSc patients, 91 deaths occurred between April 2000 and September 2020. Overall 5 and 10 year survival rates were 88.4% and 80.2%, respectively. SSc was the most common primary cause of death (n = 35) and interstitial lung disease (ILD) was the most common SSc-related cause of death (n = 13). Moreover, 52% of the patients with diffuse SSc and 33% of those with limited cutaneous SSc died as a result of SSc itself. Patients who died because of SSc were significantly younger [mean ± sd age 65.6 ± 12.7 years, 95% confidence interval (CI) 61.2-70.1] than those who died from other causes (74.2 ± 9.6 years, 95% CI 71.5-76.9) (p = 0.0006). ILD, pulmonary arterial hypertension, gastrointestinal involvement, male gender, and older age at disease onset predicted death. CONCLUSION: The disease itself was the major cause of death among Finnish SSc patients, in both diffuse and limited forms of SSc.

Differential diagnostics of polymyalgia rheumatica in a university hospital in Finland.

OBJECTIVES: Diagnosing polymyalgia rheumatica (PMR) can be difficult as many conditions present with similar symptoms and findings. This study aimed to analyse how often the diagnosis of PMR changes during follow-up in a university hospital setting and to determine the most common clinical conditions initially misdiagnosed as PMR. METHOD: All patients with a new primary diagnosis of PMR on at least one visit during the years 2016-2019 were identified from the hospital discharge register of Turku University Hospital, Finland. A diagnosis of PMR was confirmed if the patient met at least one of the five classification criteria, complete clinical follow-up (median 34 months) was compatible with PMR, and no other diagnosis better explained their condition. RESULTS: Of the patients initially diagnosed with PMR, 65.5% were considered to have PMR after further evaluation and clinical follow-up. The most common conditions initially diagnosed as PMR were inflammatory arthritides (34.9%), degenerative or stress-related musculoskeletal disorders (13.2%), infection (9.3%), malignancy (9.3%), giant cell vasculitis (6.2%) and other vasculitis (6.2%), and a wide range of other less common diseases. The diagnosis of PMR remained in 81.3% of patients who fulfilled the 2012 American College of Rheumatology/European League Against Rheumatism PMR classification criteria and in 45.5% of patients who did not. CONCLUSIONS: Diagnosing PMR is challenging, even in a university hospital. One-third of the initial diagnoses of PMR changed during further evaluation and follow-up. There is a substantial risk of misdiagnosis, especially in patients with atypical presentation, and the differential diagnoses of PMR must be considered carefully.

The validity of systemic sclerosis diagnoses in two university hospitals in Finland.

OBJECTIVE: This study aimed to determine the validity of systemic sclerosis (SSc) diagnoses in Finnish university hospitals. METHOD: Electronic medical records for 385 patients with a registered diagnosis of SSc (ICD-10 code M34) in two Finnish university hospitals from 2008 to 2018 were reviewed to assess whether each patient's diagnosis was correct. RESULTS: The positive predictive value (PPV) of a diagnosis of SSc was 0.66 when fulfilment of the 2013 American College of Rheumatology/European League Against Rheumatism (ACR/EULAR) classification criteria for SSc was required; the PPV was 0.75 if patients meeting the 2001 LeRoy and Medsger classification criteria for early SSc were also included. When a diagnosis of SSc was made in a department of rheumatology, the PPV was 0.78, and 0.90 when including patients with early SSc. For the more specific diagnosis of limited cutaneous SSc (lcSSc), the PPV was 0.80, and 0.95 when including early SSc. For an lcSSc diagnosis made in rheumatology, the PPV was 0.81, and 0.97 with early SSc included. CONCLUSION: These results demonstrate that in these two Finnish university hospitals, the diagnostic validity of a diagnosis of SSc was good if it was diagnosed in the department of rheumatology. For a more specific diagnosis of lcSSc, the most prevalent form of SSc in Finland, the validity was good even when registered in any department.

Real-world registry-based study on apremilast use in psoriasis and psoriatic arthritis in Finland.

OBJECTIVES: This study assessed the position of apremilast in the treatment pathway of psoriasis (PsO) and psoriatic arthritis (PsA) in Finnish clinical practice, compared the characteristics of apremilast and biologic therapy users, evaluated persistence with apremilast and identified factors influencing treatment discontinuation. METHOD: This retrospective study used data from Finnish national health registries. The target group was identified based on L40* diagnosis and medication records between 2015 and 2018. Treatment persistence was analysed using Kaplan-Meier curves and Cox regression. RESULTS: Of eligible patients (PsO 31 202; PsA 12 386), 1% (n = 471) used apremilast and 10% (n = 4214) biologics, apremilast users being older (mean age 55.9 vs 52.4 years, p < 0.001) with a higher Charlson comorbidity score (0.71 vs 0.54, p < 0.001). Most patients switched to apremilast from conventional synthetic therapy (PsO 75%; PsA 76%); 47% of patients remained on apremilast during the observation period (PsO 58%; PsA 42%). Most patients discontinuing apremilast switched to biologics (PsO 51%; PsA 51%). Apremilast persistence increased with age (p = 0.042) and was higher in PsO than in PsA (median 14 vs 11 months; p = 0.005). Compared to prior conventional synthetic therapy, prior biologic therapy decreased persistence (hazard ratio for discontinuation 2.15, 95% confidence interval 1.42-3.25). CONCLUSION: In Finnish clinical practice, apremilast is mainly used between conventional synthetic therapy and biologics, with at least as high treatment persistence as reported in previous studies. Apremilast users were older with higher comorbidity burden than biologics users.

The validity of rheumatoid arthritis diagnoses in Finnish biobanks.

OBJECTIVE: The aim of this study was to determine the validity of rheumatoid arthritis (RA) diagnoses in patients participating in Finnish biobanks. METHOD: We reviewed the electronic medical records of 500 Finnish biobank participants: 125 patients with at least one visit with a diagnosis of seropositive RA, 125 patients with at least one visit with a diagnosis of seronegative RA, and 250 age- and gender-matched controls. The patients were chosen from five different biobank hospitals in Finland. A rheumatologist reviewed the medical records to assess whether each patients' diagnosis was correct. The diagnosis was compared with the diagnostic codes in the Finnish Care Register for Health Care (CRHC) and special reimbursement data of the Social Insurance Institution of Finland. RESULTS: The positive predictive value (PPV) of CRHC diagnosis of RA (for seropositive and seronegative RA combined) was 0.82. For patients with a special reimbursement for anti-rheumatic medications for RA, the PPV was 0.89. The PPV was higher in patients with more than one visit. For one, two, five, and 10 visits, the PPV was 0.82, 0.85, 0.89, and 0.90, respectively, and for patients who also had the special reimbursement, the PPV was 0.89, 0.91, 0.93, and 0.94 for one, two, five, and 10 visits, respectively. In patients positive for anti-citrullinated protein antibodies, the PPV was 0.98. CONCLUSION: These results demonstrate that the validity of RA diagnoses in Finnish biobanks was good and can be further improved by including data on special reimbursement for medication, number of visits, and serological data.

Immunogenicity of subcutaneous TNF inhibitors and its clinical significance in real-life setting in patients with spondyloarthritis.

KEY MESSAGES: Considerable proportion of patients with SpA have been immunized to the subcutaneous anti-TNF drug they are using. Concomitant use of MTX protects from immunization, whereas SASP does not. Patients with SpA using subcutaneous anti-TNF drugs can benefit from monitoring of the drug trough levels. Immunization to biological drugs can lead to decreased efficacy and increased risk of adverse effects. The objective of this cross-sectional study was to assess the extent and significance of immunization to subcutaneous tumor necrosis factor (TNF) inhibitors in axial spondyloarthritis (axSpA) patients in real-life setting. A serum sample was taken 1-2 days before the next drug injection. Drug trough concentrations, anti-drug antibodies (ADAb) and TNF-blocking capacity were measured in 273 patients with axSpA using subcutaneous anti-TNF drugs. The clinical activity of SpA was assessed using the Bath AS Disease Activity Index (BASDAI) and the Maastricht AS Entheses Score (MASES). ADAb were found in 11% of the 273 patients: in 21/99 (21%) of patients who used adalimumab, in 0/83 (0%) of those who used etanercept, in 2/79 (3%) of those who used golimumab and in 6/12 (50%) of those who used certolizumab pegol. Use of methotrexate reduced the risk of formation of ADAb, whereas sulfasalazine did not. Presence of ADAb resulted in decreased drug concentration and reduced TNF-blocking capacity. However, low levels of ADAb had no effect on TNF-blocking capacity and did not correlate with disease activity. The drug trough levels were below the consensus target level in 36% of the patients. High BMI correlated with low drug trough concentration. Patients with low drug trough levels had higher disease activity. The presence of anti-drug antibodies was associated with reduced drug trough levels, and the patients with low drug trough levels had higher disease activity. The drug trough levels were below target level in significant proportion of patients and, thus, measuring the drug concentration and ADAb could help to optimize the treatment in SpA patients.

Drug survival on tumour necrosis factor inhibitors in patients with rheumatoid arthritis in Finland.

OBJECTIVE: A systematic review found that an average of 27% of rheumatoid arthritis (RA) patients using tumour necrosis factor (TNF) inhibitors discontinue their treatment within 1 year. The aim of this study was to assess drug survival on TNF inhibitors among patients with RA. METHODS: Patients were identified from the National Register for Biologic Treatment in Finland (ROB-FIN), which is a longitudinal cohort study established to monitor the effectiveness and safety of biologic drugs in rheumatic diseases. Inclusion was limited to TNF-inhibitor treatments started as the patient's first, second, or third biologic treatment between 2004 and 2014. Follow-up was truncated at 36 months. The results of a time-dependent Cox proportional hazards model were reported as adjusted hazard ratios (HRs) with 95% confidence intervals (CIs). RESULTS: Of the 4200 TNF-inhibitor treatment periods identified from ROB-FIN, 3443 periods from 2687 patients met the inclusion criteria. Twenty-seven per cent of the patients discontinued their treatment within 12 months. Infliximab (HR 1.8, 95% CI 1.3-2.5) and certolizumab pegol (HR 1.7, 95% CI 1.2-2.3) had lower drug survival compared to golimumab. A similar trend was seen with adalimumab (HR 1.2, 95% CI 0.90-1.7) and etanercept (HR 1.2, 95% CI 0.87-1.6). Concomitant use of methotrexate (MTX) was associated with improved drug survival (HR 0.76, 95% CI 0.64-0.90) in comparison with TNF-inhibitor monotherapy. CONCLUSIONS: Golimumab was better in terms of drug survival than infliximab or certolizumab pegol and at least as good as adalimumab and etanercept. Concomitant use of MTX improved drug survival on TNF inhibitors.

Three out of four disease-modifying anti-rheumatic drug-naïve rheumatoid arthritis patients meet 28-joint Disease Activity Score remission at 12 months: results from the FIN-ERA cohort.

OBJECTIVE: To assess what proportion of patients with disease-modifying anti-rheumatic drug (DMARD)-naïve early rheumatoid arthritis (ERA) reach 28-joint Disease Activity Score (DAS28) remission over 1 year, and remission variability across clinics in Finland. METHOD: Patients with DMARD-naïve newly diagnosed inflammatory arthritis were recruited. The proportion of patients in 28-joint Disease Activity Score with three variables (DAS28-3) remission was compared across sites. Repeated measures were analysed using a mixed models approach with appropriate distribution and link function. RESULTS: In total, 611 patients were recruited at five sites: 67% were female; the mean (sd) age was 57 (16) years; 71% and 68% were positive for rheumatoid factor and anti-cyclic citrullinated peptides, respectively; and 23% had radiographic erosions. A total of 506 (83%) fulfilled the American College of Rheumatology/European League Against Rheumatism 2010 classification criteria for rheumatoid arthritis for further analyses. DAS28-3 remission was met by 68% and 75% at 3 and 12 months, respectively. The clinical site had no effect on remission when adjusted for confounders. At baseline, 68% used methotrexate-based combination therapy, and 31% used triple therapy with methotrexate, hydroxychloroquine, and sulphasalazine (the Fin-RACo regimen). In multivariate analysis, the only independent predictors of DAS28-3 remission at 12 months were lower baseline DAS28-3 and triple therapy as the initial treatment. CONCLUSION: Three out of four DMARD-naïve ERA patients in Finland are in remission during the first year from the diagnosis. High remission rates were achieved for most patients with the use of conventional synthetic DMARDs in combination. Treatment of DMARD-naïve ERA patients with the FIN-RACo regimen is a predictor of DAS28-3 remission in real-life rheumatology settings.

Measuring the economic value of morning stiffness: consistency over 1 year.

OBJECTIVES: The aims of this study were to determine the within-patient variation in the duration of morning stiffness (MS) over 1 year and the corresponding monetary equivalents assigned to its changes using the willingness-to-pay (WTP) methodology. METHOD: A sample of 100 patients with rheumatoid arthritis (RA) was drawn from the register of the Hospital District of Southwest Finland. Subjects were interviewed by telephone on recruitment and 1 year later, using the same structured questionnaire. The subjects were asked to estimate in minutes the typical duration of their MS during the previous week. Sociodemographic background data and subjects' WTP for a 25, 50, 75, and 100% reduction in MS duration were requested, and years with RA diagnosis and serological data were obtained from hospital records. RESULTS: After 1 year, there was a reduction in average MS duration from 44.7 min to 39.0 min (ns); duration was reduced in 35% of patients, unchanged in 35%, and prolonged in 30%. Changes in MS duration were reflected by within-patient variation in WTP estimates. In linear regression models, change in duration of MS significantly (p < 0.03) explained the variation in change of WTP for symptom reduction. CONCLUSIONS: WTP methodology produces consistent monetary values to assess the relative values patients with RA place on reduction in duration of MS.

Effects of liposomal antisense oligonucleotides on mRNA and protein levels of the HPV 16 E7 oncogene.

Despite the known association of human papillomavirus (HPV) infection with cervical cancer there is no specific antiviral treatment for HPV infection. Antisense oligode-oxynucleotides (AS-ODNs) may offer an effective way to treat HPV infections as the stability and delivery have been improved using modified ODNs or carrier systems. In this study we investigated the effects of liposomal AS-ODNs (0.1, 1 and 5 microM) on HPV 16 E7 mRNA and protein levels in CaSki cells. We used cationic liposomes (10 microM) containing dimethyldioctadecylammonium bromide (DDAB) or 2,3-dioleyloxy-N-[2(sperminecar-boxamido)ethyl]-N, N-dimethyl-1-propanaminium trifluoroacetate (DOSPA). Both these liposomes had dioleoylphosphatidyl-ethanolamine (DOPE) as a helper lipid. The target of the AS-ODNs was E7 protein because it is the one of the two oncoproteins of HPV 16. Only liposomal AS-ODNs which were targeted to the initiation codon of E7, had an effect on E7 mRNA expression; two shorter transcripts were detected, suggesting that RNase H degradation was activated. Liposomal random ODN or liposomal ODN targeted downstream from the initiation site of E7 did not affect the mRNA pattern. However, no change was found in the E7 protein levels detected by immunoprecipitation. Further studies showed that AS-ODNs inhibited the translation of E7 mRNA in a rabbit reticulocyte lysate assay. This data, together with the changes in mRNA levels, proved that the AS-ODNs reached the target mRNA. One possible explanation for the unchanged protein level of E7 in CaSki cells might be that immunoprecipitation is not sensitive enough to detect minor changes in protein levels. However, further progress is still needed in the field of carrier systems and modifications of AS-ODNs before non-sequence specific effects can be avoided.

Cross-sensitivity within the neomycin group of antibiotics.

Neomycin sensitive patients were tested for hypersensitivity to kanamycin, gentamycin, tobramycin, spectinomycin and to the new, not yet registered sisomycin and netilmicin. Cross-sensitivity occured in a considerable part of the patients, except for spectinomycin, the structure of which is basically different from that of the other aminoglycosides tested. The common occurence of cross-sensitivity between neomycin and other aminoglycoside antibiotics shows that it is possible to predict cross-sensitivity between a new drug and an old sensitizing one before clinical reactions from the new drug have occured. Such an investigation should be performed before adopting new antibiotics.

Syndecan-1 expression is upregulated in degenerating articular cartilage in a transgenic mouse model for osteoarthritis.

OBJECTIVE: Mice heterozygous for the Del1 transgene locus with a short deletion mutation in the type II collagen gene develop early-onset degenerative changes in the knee joints that progress to end-stage osteoarthritis by the age of 12-15 months. This study focuses on the expression and distribution of syndecan-1, a cell-surface heparan sulfate proteoglycan, during the development of osteoarthritic cartilage degeneration, to better understand its role in this disease. METHODS: Northern analyses of total RNA extracted from knee joints of transgenic Del1 mice and their nontransgenic controls were used to monitor changes in syndecan-1 mRNA levels during development, growth, ageing, and cartilage degeneration. Immunohistochemistry was used to study the distribution of syndecan-1 in the knee joints at different stages of cartilage degeneration. RESULTS: Syndecan-1 mRNA was present in knee joints throughout life, with the highest mRNA levels in ageing knee joints. In Del1 mice, a transient upregulation of syndecan-1 mRNA synthesis was observed at the age of 6 months coinciding with early stages of cartilage degeneration and a period of attempted repair. Immunostaining for syndecan-1 was most intense in chondrocytes of superficial and intermediate zones of articular cartilage adjacent to defect areas. Chondrocyte clusters also stained strongly for syndecan-1. CONCLUSION: The present temporospatial expression data on upregulation of syndecan-1 in articular cartilage during early stages of cartilage degeneration suggest that this molecule is involved in the attempted repair of cartilage fibrillations. Combined with the known role of syndecan-1 during skeletal development and wound healing, this interesting finding warrants further validation.

Altered integrin expression in rheumatoid synovial lining type B cells: in vitro cytokine regulation of alpha 1 beta 1, alpha 6 beta 1, and alpha v beta 5 integrins.

OBJECTIVE: We recently showed that in rheumatoid arthritis (RA) the extracellular matrix around the lining cells is similar to the matrix seen in osteoarthritis, whereas the cellular adhesion apparatus is very different. In hyperplastic synovial membrane there is very little of alpha 6, alpha v, and beta 5 integrin subunits, whereas in noninflammatory synovial membrane these integrins are well expressed. We studied how expression of these cell adhesion molecules is regulated in RA in vitro. METHODS: The integrin expression in 6 different synovial fibroblast strains representing the type B cells and in THP-1 cell line was examined by immunoprecipitation, flow cytometry, and Northern hybridization. RESULTS: Proinflammatory cytokines, especially interleukin 1 beta, increased the expression of alpha 1 integrin in synovial fibroblasts. When the monocyte-like THP-1 cells were induced to differentiate to adherent macrophages they started to express alpha 6 and beta 5 integrin subunits. In adherent THP-1 cells the expression of integrin alpha 6 subunit was strongly enhanced by transforming growth factor-beta and downregulated by the combination of tumor necrosis factor-alpha and interferon-gamma. CONCLUSION: Cytokines regulate the cell adhesion molecules of synovial fibroblasts and mononuclear phagocytes in vitro causing alterations in integrin expression similar to the ones seen in rheumatoid synovium in vivo.

Bone morphogenetic protein-2 is a regulator of cell adhesion.

Bone morphogenetic proteins (BMPs) are a group of peptide growth factors closely related to transforming growth factors-beta. The BMPs are suggested to play an essential role in bone development and they are strong candidate molecules to be used clinically to improve fracture healing. BMPs are also involved in the differentiation of several other tissues during embryogenesis. Here, we show that human recombinant BMP-2 regulates cell-matrix interactions by modifying the expression of integrin-type receptors. The synthesis of alpha3 integrin was down-regulated by BMP-2 in two osteogenic sarcoma-derived cell lines, Saos-2 and HOS, and also in human fetal chondrocytes. BMP-2 had no effect on the expression of alpha1, alpha2, alpha5, alpha6, and alphaV integrins. BMP-2 reduced the expression of alpha3 integrin subunit at mRNA level. Laminin-5 was shown to be the ligand for alpha3beta1 integrin on Saos cells and BMP-2 decreased the ability of Saos cells to attach to it. These results suggest that BMP-2 has a specific effect on the alpha3beta1 integrin-mediated cell adhesion to laminin-5. Given the fact that BMP-2 is expressed in osteosarcomas, in addition to in bone, this mechanism is putatively important especially in bone development and tumors. We also studied the effect of BMP-2 on a human keratinocyte cell line, HaCaT. In HaCaT cells, the expression of alpha2 integrin was strongly down-regulated by BMP-2, whereas its effect on the expression of alpha3 integrin was smaller. We suggest that the effects of BMP-2 may be partially mediated by specifically altered cell adhesion.

Expression of the myc-family proto-oncogenes and related genes max and mad in synovial tissue.

OBJECTIVE: To examine the expression of myc proto-oncogenes; c-myc, L-myc, and N-myc, and their related genes max and mad, in the arthritic synovium. METHODS: Using reverse transcription-polymerase chain reaction (RT-PCR), Northern and Southern hybridizations, the expression of these genes in the synovial tissue from rheumatoid arthritis (RA) and osteoarthritis (OA) was analyzed. Synovial specimens from cadavers without any joint disease and peripheral blood mononuclear cells (PBMC) from healthy individuals served as controls. RESULTS: As a novel finding, synovial cells were observed to express L-myc, N-myc as well as their related genes max and mad, in addition to the previously described presence of c-myc proto-oncogene in synovium. c-myc, L-myc, N-myc, and mad were expressed in all patient samples studied, including the controls. Instead, max was detected in only 10/12 of RA patients, in 11/13 of OA patients, and in all controls (4/4 cadavers, 5/5 blood donors). Six patients with RA revealed positive signals for max only after hybridization. The same was also true of two patients with OA and of one healthy individual donating blood. CONCLUSIONS: The L-myc, N-myc, max, and mad genes are expressed in synovial cells, in addition to c-myc proto-oncogene. However, expression of these genes is not disease-specific, since they were equally expressed in synovial samples from patients with RA or OA as well as from cadavers representing controls without any joint disease.

Identification of alpha6beta1 integrin positive cells in synovial lining layer as type B synoviocytes.

OBJECTIVE: In rheumatoid arthritis (RA) the synovial lining is responsible for cartilage destruction. Laminin is one of the major matrix molecules surrounding the lining cells. We investigated the laminin adhesion mechanism of synovial lining cells by analyzing the presence of its receptor, alpha6beta1 integrin, on type A and type B synoviocytes. METHODS: The alpha6 integrin subunit and a macrophage marker were simultaneously localized by immunohistochemistry in 29 RA derived, 6 osteoarthritis derived, and 2 healthy synovial samples by light and electron microscopy. We also used enzyme treatments to release cells from synovial tissue samples and localized the same antigens on adherent cells. RESULTS: The alpha6beta1 integrin positive cells were localized in basal areas of the lining layer and many of them were negative for the macrophage markers. By immunolabeling electron microscopy the alpha6 integrin positive cells were confirmed to represent the fibroblast-like type B cells. Further, in freshly isolated synoviocyte cultures the type B cells were positive for alpha6 integrin, whereas all other cell types were negative for this laminin receptor. CONCLUSION: Integrin alpha6beta1 is known to be a laminin receptor of endothelial cells, adipocytes, and macrophages, not usually expressed on fibroblasts. However, in synovial lining layer it is expressed on fibroblastic type B cells, but the macrophage population is negative. The unique characteristics of synovial lining cells distinguish them from other connective tissue cells and must be taken into account in all considerations of the pathogenic mechanisms of rheumatoid disease.

H-ras oncogene point mutations in arthritic synovium.

OBJECTIVE: To examine mutational activation of ras proto-oncogenes in synovial tissue from patients with rheumatoid arthritis (RA) compared with synovial specimens from patients with osteoarthritis (OA) or other arthropathies. Synovial samples from cadavers, without any signs of joint disease, were used as control material. METHODS: Using a combination of polymerase chain reaction (PCR) and automated sequencing of the amplified PCR product, regions around codons 12, 13, and 61 of the H-, K-, and N-ras proto-oncogenes were analyzed. Confirmation of mutations was based on restriction fragment length polymorphism analysis and/or oligonucleotide hybridization. RESULTS: Four (6%) of 72 patients with RA, 2 (13%) of 16 with OA, and 1 (8%) of 12 with other arthropathies harbored mutant H-ras proto-oncogenes, and were heterozygous at codon 13 for the GGT-->GAT (Gly-->Asp) change. An unexpected mutation was found in the H-ras gene, in which a heterozygous GTG-->ATG (Val-->Met) mutation was observed over codon 14. The incidence for this mutation was 39% (28 of 72) in RA patients, 94% (15 of 16) in OA patients, and 42% (5 of 12) in patients with other arthropathies. All samples carrying the codon 13 mutation of H-ras were also codon 14-mutated, i.e., double mutations existed. Identical point mutations were also detected in a few synovial specimens obtained from cadavers (n = 8), including a single case of double mutation. All specimens showed normal K- and N-ras loci. CONCLUSION: Activation of proto-oncogene H-ras by point mutation in codons 13 and 14 occurred in the synovial tissue of patients with RA, OA, or other arthropathies, as well as, to some extent, in the control synovia, indicating that the phenomenon is not specific for RA. In codon 14, incidence of the H-ras point mutation was highest in OA tissue. The possible significance of this codon 14-mutated H-ras gene needs to be clarified.