The serological immunogenicity of the third and fourth doses of COVID-19 vaccine in patients with inflammatory rheumatic diseases on different biologic or targeted DMARDs: a Swedish nationwide study (COVID-19-REUMA).

Studies investigating the immunogenicity of additional COVID-19 vaccine doses in immunosuppressed patients with inflammatory rheumatic diseases (IRD) are still limited. The objective was to explore the antibody response including response to omicron virus subvariants (sBA.1 and sBS.2) after third and fourth COVID-19 vaccine doses in Swedish IRD patients treated with immunomodulating drugs compared to controls. Antibody levels to spike wild-type antigens (full-length protein and S1) and the omicron variants sBA.1 and sBA.2 (full-length proteins) were measured. A positive response was defined as having antibody levels over cut-off or ≥fourfold increase in post-vaccination levels for both antigens. Patients with arthritis, vasculitis, and other autoimmune diseases (n = 414), and controls (n = 61) receiving biologic/targeted synthetic disease-modifying anti-rheumatic drugs (DMARDs) with or without conventional synthetic DMARDs participated. Of these, blood samples were available for 370 patients and 52 controls after three doses, and 65 patients and 15 controls after four doses. Treatment groups after three vaccine doses were rituximab (n = 133), abatacept (n = 22), IL6r inhibitors (n = 71), JAnus Kinase inhibitors (JAK-inhibitors) (n = 56), tumor necrosis factor inhibitor (TNF-inhibitors) (n = 61), IL12/23/17 inhibitors (n = 27), and controls (n = 52). The percentage of responders after three and four vaccine doses was lower in rituximab-treated patients (59% and 57%) compared to controls (100%) (P < 0.001). After three doses, the percentage of responders in all other groups was 100%, including response to omicron sBA.1 and sBA.2. In rituximab-treated patients, higher baseline immunoglobulin G (IgG) and longer time-period between rituximab and vaccination predicted better response. In this Swedish nationwide study including IRD patients three and four COVID-19 vaccine doses were immunogenic in patients treated with IL6r inhibitors, TNF-inhibitors, JAK-inhibitors, and IL12/23/17-inhibitors but not in rituximab. As >50% of rituximab patients responded to vaccines including omicron subvariants, these patients should be prioritized for additional vaccine doses. IMPORTANCE: Results from this study provide further evidence that additional doses of COVID-19 vaccines are immunogenic and result in satisfactory antibody response in a majority of patients with inflammatory rheumatic diseases (IRD) receiving potent immunomodulating treatments such as biological or targeted disease-modifying anti-rheumatic drugs (DMARDs) given as monotherapy or combined with traditional DMARDs. We observed that rituximab treatment, both as monotherapy and combined with csDMARDs, impaired antibody response, and only roughly 50% of patients developed a satisfactory antibody response including response to omicron subvariants after the third vaccine. In addition, higher IgG levels at the last rituximab course before the third vaccine dose and a longer time after the last rituximab treatment increased the chance of a satisfactory antibody response. These results indicate that rituximab-treated patients should be prioritized for additional vaccine doses. CLINICAL TRIALS: EudraCT (European Union Drug Regulating Authorities Clinical Trials Database) with number 2021-000880-63.

Associations between serological biomarkers and subclinical atherosclerosis in patients with rheumatoid arthritis after 11 years of follow-up.

OBJECTIVES: To investigate the relationship between biomarkers known to be involved in both chronic inflammation and subclinical atherosclerosis, as measured by carotid intima media thickness (cIMT), in patients with RA compared to controls. METHODS: Between 2000 and 2004, all patients under 60 years of age with newly diagnosed RA in the northern region of Sweden were invited to participate in this study. Measurements of cIMT were undertaken at inclusion (T0), after five years of follow-up (T5) and after eleven years of follow-up (T11). Patients were clinically assessed and blood was drawn for analysis of biomarkers. RESULTS: In patients with RA (n=54), linear regression models showed that cIMT at T11 was associated with levels of GDF-15 at T5 and T11, but not with baseline levels. GDF-15 was strongly associated with age. At T11, mean level of GDF-15 was elevated compared to controls. Levels of adiponectin, MCP-1, cathepsin S, endoglin and IL-6 were higher in patients with RA compared to controls, but showed no association with cIMT. In multivariable linear regression models with cIMT at T11 as dependent variable, change in GDF-15 from T0 to T11 was associated to an increase in cIMT at T11. Adjusting for systolic blood pressure and age respectively rendered this association statistically non-significant,CONCLUSIONS: Among these patients with RA GDF-15 was associated to cIMT after 11 years of follow-up. GDF-15 should be a biomarker of interest in future research, to further understand its role in the accelerated atherogenesis in patients with RA.

Heart rate variability and cardiovascular risk factors in patients with rheumatoid arthritis: A longitudinal study.

BACKGROUND: It is established that the risk of cardiovascular disease (CVD) is increased in patients with Rheumatoid Arthritis (RA). Heart rate variability (HRV) is a method for evaluating the activity in the cardiac autonomic nervous system. Our aim was to assess the longitudinal development of HRV in patients with RA and compare with healthy controls. Furthermore, we wanted to investigate associations between HRV, inflammatory disease activity and cardiovascular complications in patients with RA over time. METHOD: HRV was assessed with frequency-domain analysis at baseline and after five years in 50 patients with early RA, all being younger than 60 years. HRV indices were age-adjusted based on the estimated age-dependency in 100 age and sex matched healthy controls. Additionally, clinical data including serological markers, disease activity, and blood pressure were collected from the patients. Eleven years after inclusion CVD was assessed. RESULTS: At baseline, patients with RA presented with lower HRV compared to controls during deep breathing (6 breaths/min), paced normal breathing (12 breaths/min) and after passive tilt to the upright position. No significant change in HRV was observed at the five-year follow-up. A significant negative correlation was found between HRV parameters and systolic blood pressure (SBP) at baseline. A significant positive correlation was found between heart rate and inflammatory markers at baseline but not after five years. Nine patients had developed CVD after 11 years, but no significant association was found with baseline HRV data. CONCLUSION: This study showed that patients with RA have autonomic imbalance both at an early stage of the disease and after five years, despite anti-rheumatic medication, but no correlation between HRV and inflammation markers were observed. Reduced HRV was also significantly negatively correlated with increased SBP. Hypertension is a common finding in patients with RA. Thus, significant decline of HRV could be a useful early marker for development of hypertension in patients with RA.

The impact of immunomodulating treatment on the immunogenicity of COVID-19 vaccines in patients with immune-mediated inflammatory rheumatic diseases compared to healthy controls. A Swedish nationwide study (COVID19-REUMA).

OBJECTIVES: To elucidate antibody responses after the second and third dose of COVID-19 vaccine in patients with inflammatory rheumatic diseases (IRD) treated with biologic/targeted disease modifying anti-rheumatic drugs (b/ts DMARDs). METHODS: Antibody levels to antigens representing spike full length protein and spike S1 were measured before vaccination, 2-12 weeks after the second dose, before and after the third dose using multiplex bead-based serology assay. Positive antibody response was defined as antibody levels over cut off (seropositivity) in seronegative individuals or ≥ 4-fold increase in antibodies in individuals seropositive for both spike proteins. RESULTS: Patients (n = 414) receiving b/ts DMARDs (283 had arthritis, 75 systemic vasculitis and 56 other autoimmune diseases) and controls (n = 61) from five Swedish regions participated. Treatments groups were: rituximab (n = 145); abatacept (n = 22); Interleukin 6 receptor inhibitors [IL6i (n = 79)]; JAnus Kinase Inhibitors [JAKi (n = 58)], Tumour Necrosis Factor inhibitor [TNFi (n = 68)] and Interleukin12/23/17 inhibitors [IL12/23/17i (n = 42)]. Percentage of patients with positive antibody response after two doses was significantly lower in rituximab (33,8%) and abatacept (40,9%) (p < 0,001) but not in IL12/23/17i, TNFi or JAKi groups compared to controls (80,3%). Higher age, rituximab treatment and shorter time between last rituximab course and vaccination predicted impaired antibody response. Antibody levels collected 21-40 weeks after second dose decreased significantly (IL6i: p = 0,02; other groups: p < 0,001) compared to levels at 2-12 week but most participants remained seropositive. Proportion of patients with positive antibody response increased after third dose but was still significantly lower in rituximab (p < 0,001). CONCLUSIONS: Older individuals and patients on maintenance rituximab have an impaired response after two doses of COVID-19 vaccine which improves if the time between last rituximab course and vaccination extends and also after an additional vaccine dose. Rituximab patients should be prioritized for booster vaccine doses. TNFi, JAKi and IL12/23/17i does not diminished humoral response to primary and an additional vaccination.

Time Trends of Cardiovascular Disease in the General Population and Inflammatory Arthritis.

Cardiovascular diseases (CVDs) are the leading causes of death in the world, but declining trends for cardiovascular (CV) mortality and morbidity have been observed during the last decades. Reports on secular trends regarding the excess CV mortality and morbidity in rheumatoid arthritis show diverging results. Data support that also patients with inflammatory arthritis have benefited from improved treatment and prevention for CVD, which can be observed, for example, in decreased case fatality after CV event. However, several recent studies indicate a remaining excess CV risk in patients with inflammatory arthritis.

Individual Regression Modeling of Spinal Mobility Measurements in Long-Term Ankylosing Spondylitis: In-Depth Analyses With Comparison to Norm Data.

OBJECTIVE: Normal age-related decline and temporary restrictions in mobility complicate the understanding of spinal mobility deterioration over time in patients with ankylosing spondylitis (AS). In this study, we aimed to determine whether spinal mobility deterioration occurred linearly in patients with AS. We also aimed to compare patterns of change with corresponding age-related normal values and analyze variations in temporary fluctuations in mobility measurements over time. METHODS: We included 111 men and 30 women (median age 20.9 years at symptom onset), who were followed for a median of 34 years since symptom onset. This inclusion resulted in 9,697 spinal mobility measurements for analysis. Individual linear regression models for development of lateral spinal flexion (LSF), the 10-cm Schober test (ST10), chest expansion (CE), and cervical rotation (CR) were analyzed and compared with normal age-related decline over time. RESULTS: The median values for the constants of all measurements were significantly lower than the norm data. However, LSF, ST10, and CE followed a yearly linear decline comparable to the norm data, whereas CR declined approximately twice as fast as expected from the norm data (beta median -0.62° [25th-75th percentile -1.16, -0.22] and -0.35° [25th-75th percentile -0.35, -0.35], respectively). Temporary fluctuations in LSF and CE were significantly higher during the early phase of the disease, with decreasing residuals over time. CONCLUSION: Based on median constants of our data, mobility restrictions related to AS seem to mainly occur during the first years of disease, indicating a narrow window of opportunity for prevention.

Osteoprotegerin and osteocalcin are associated with atherosclerosis in patients with rheumatoid arthritis: a prospective cohort study.

OBJECTIVES: Patients with rheumatoid arthritis (RA) have an accelerated progression of atherosclerosis. The aim of this study was to examine the associations between subclinical atherosclerosis, assessed by intima-media thickness (IMT), and regulators of bone formation, markers of bone turnover and bone mineral density (BMD) in patients with RA. METHODS: Patients with new-onset RA (n=79), aged ≤60 years at diagnosis, were consecutively included in a study of development of atherosclerosis. Ultrasound measurement of IMT of the common carotid artery was undertaken at inclusion (T0) and after 11 years (T11) (n=54). Bone turnover biomarkers were examined in samples collected at T0 and T11. BMD was assessed at T11. RESULTS: In patients with RA, osteocalcin (OCN) and osteoprotegerin (OPG) measured at T11 were significantly associated with IMT at T11, adjusted for systolic blood pressure (SBP) and age. BMD at T11 and the bone turnover markers procollagen type 1 N-terminal propeptide (P1NP) and carboxy-terminal crosslinked C-terminal telopeptide (CTX) were not associated with IMT. OPG, OCN and sclerostin at T0 were significantly associated with IMT at T11, and OPG and OCN at T0 were associated with change in IMT from T0 to T11. The associations between IMT and bone biomarkers were stronger in patients with joint erosions at onset of RA, than in patients with non-erosive disease. CONCLUSIONS: Atherosclerosis in patients with RA is associated with OPG and OCN, but not with BMD or markers reflecting ongoing bone turnover, indicating that atherosclerosis is not associated with bone turnover per se.

Isotemporal Substitution of Time Between Sleep and Physical Activity: Associations With Cardiovascular Risk Factors in Early Rheumatoid Arthritis.

OBJECTIVE: We aimed to determine relationships between objectively measured nightly sleep, sedentary behavior (SB), light physical activity (LPA), and moderate to vigorous physical activity (MVPA) with risk factors for cardiovascular disease (CVD) in patients with early rheumatoid arthritis (RA). Furthermore, we aimed to estimate consequences for these risk factors of theoretical displacements of 30 minutes per day in one behavior with the same duration of time in another. METHODS: This cross-sectional study included 78 patients with early RA. Nightly sleep, SB, LPA, and MVPA were assessed by a combined heart rate and accelerometer monitor. Associations with risk factors for CVD were analyzed using linear regression models and consequences of reallocating time between the behaviors by isotemporal substitution modeling. RESULTS: Median (Q1-Q3) nightly sleep duration was 4.6 (3.6-5.8) hours. Adjusted for monitor wear time, age, and sex, 30-minutes-longer sleep duration was associated with favorable changes in the values ß (95% confidence interval [CI]) for waist circumference by -2.2 (-3.5, -0.9) cm, body mass index (BMI) by -0.9 (-1.4, -0.4) kg/m2 , body fat by -1.5 (-2.3, -0.8)%, fat-free mass by 1.6 (0.8, 2.3)%, sleeping heart rate by -0.8 (-1.5, -0.1) beats per minute, and systolic blood pressure by -2.5 (-4.0, -1.0) mm Hg. Thirty-minute decreases in SB, LPA, or MVPA replaced with increased sleep was associated with decreased android fat and lower systolic blood pressure levels. Replacement of SB or LPA with MVPA yielded lower BMIs. CONCLUSION: Shorter sleep during the night is common among patients with early RA and is associated with adverse risk factors for CVD.

Characteristics and outcome of a first acute myocardial infarction in patients with ankylosing spondylitis.

OBJECTIVES: To study clinical characteristics, mortality, and secondary prevention, after a first incident acute myocardial infarction (AMI) in patients with ankylosing spondylitis (AS) compared with the general population. METHODS: In total, 292 subjects with AS and a first AMI between Jan 2006 and Dec 2014 were identified using the Swedish national patient register. Each subject was matched with up to 5 general population comparators per AS-patient (n = 1276). Follow-up started at the date of admission for AMI and extended until death or 365 days of follow-up. Cox regression was used to assess mortality in two time intervals: days 0-30 and days 31-365. For a subgroup with available data, clinical presentation at admission, course, treatment for AMI, and secondary prevention were compared. RESULTS: During the 365-day follow-up, 56/292 (19%) AS patients and 184/1276 (14%) comparators died. There were no difference in mortality due to cardiovascular-related causes, although the overall mortality day 31-365 was increased among patients with AS compared with comparators (HR [95% CI] = 2.0 [1.3;3.0]). At admission, AS patients had a higher prevalence of cardiovascular comorbidities compared with comparators. At discharge, patients with AS were less often prescribed lipid-lowering drugs and non-aspirin antiplatelet therapy. CONCLUSIONS: Patients with AS tend to have a higher comorbidity burden at admission for first AMI. The mortality after a first AMI due to cardiovascular-related causes does not seem to be elevated, despite an increased overall mortality during days 31-365 among patients with AS compared with the general population. Key Points • The all-cause mortality after a first AMI was higher in patients with AS. • Mortality after a first AMI due to CVD-related causes does not seem to be elevated for patients with AS. • In patients with AS suffering a first AMI, more attention should be given to other comorbidities causing an excess in mortality.

Atherosclerosis in rheumatoid arthritis: associations between anti-cytomegalovirus IgG antibodies, CD4+CD28null T-cells, CD8+CD28null T-cells and intima-media thickness.

OBJECTIVES: Patients with rheumatoid arthritis (RA) have an accelerated progression of atherosclerosis. The aims of this study were to study the associations between subsets of T-cells, subclinical atherosclerosis assessed by intima-media thickness (IMT) and serological status for CMV in patients with RA. METHODS: Patients with new-onset RA (n=79), aged ≤60 years at diagnosis, were included in a prospective study of atherosclerosis. Controls matched for age and sex were also included (n=44). Ultrasound measurement of IMT in the common carotid artery was undertaken at inclusion (T0), after 1.5 years (T1.5) and after 11 years (T11). At T11, flow-cytometry analysis was undertaken to investigate subsets of T-cells. Serological analysis for CMV was undertaken from samples collected at T0. RESULTS: At T0, 66% of the patients and controls were CMV immunoglobulin G-positive. CMV-IgG positive patients had a significantly more rapid increase in IMT at T1.5, compared with controls and CMV-IgG negative patients. CMV-IgG positive patients had a significantly higher percentage of T-cells lacking CD28 (both CD4+CD28null and CD8+CD28null T-cells) than CMV-IgG negative patients. Increased levels of CD4+CD28null and CD8+CD28null T-cells were significantly associated with IMT at T11, adjusted for systolic blood pressure. CX3CR1 was expressed in CD4+ and CD8+ CD28null T-cells, but CX3CR1 per se was not associated with increased IMT. CONCLUSIONS: Presence of CMV IgG-antibodies in patients with RA is associated with altered T-cell-populations and an increased burden of atherosclerosis. A possible protective effect of antiviral treatment in CMV-positive patients with new-onset RA should be considered.

Aerobic capacity is associated with disease activity and cardiovascular risk factors in early rheumatoid arthritis.

OBJECTIVES: The aim of this study was to investigate aerobic capacity and its associations with disease activity and risk factors for cardiovascular disease (CVD) in early rheumatoid arthritis (RA). METHODS: This cross-sectional study included 67 patients with early RA. Aerobic capacity was estimated with the Åstrand submaximal test adjusted according to the Nord-Tröndelag Health Study formula. The following were also assessed: subclinical atherosclerosis by carotid intima-media thickness and pulse wave analysis; body composition by dual X-ray absorptiometry; estimated CVD mortality risk by the Systematic Coronary Risk Evaluation; disease activity by the Disease Activity Score 28, C-reactive protein and erythrocyte sedimentation rate; blood lipids by total cholesterol, low-density lipoproteins, high-density lipoproteins, and triglycerides; and functional ability by the Stanford health assessment questionnaire. Univariate and multiple linear regression analyses were performed to explore the associations between variables. RESULTS: The mean (SD) aerobic capacity was 31.6 (8.7) ml O2 -1 kg min-1 . Disease activity and risk factors for CVD were more favourable for patients with aerobic capacity above the median value. Aerobic capacity was associated with ESR and several CVD risk factors, independent of age and sex. In a multiple regression model that was adjusted for age and sex, aerobic capacity was significantly associated with per cent body fat (ß = -0.502, 95% CI [-0.671, -0.333]) and triglycerides (ß = -2.365, 95% CI [-4.252, -0.479]). CONCLUSIONS: Disease activity and risk factors for CVD were in favour for patients with a higher aerobic capacity. Aerobic capacity was associated with disease activity and several risk factors for CVD, independent of age and sex. In RA, these findings may provide insights into the benefits of using aerobic capacity as a marker to prevent CVD.

Biomarkers associated with cardiovascular disease in patients with early rheumatoid arthritis.

OBJECTIVES: Patients with rheumatoid arthritis (RA) have an increased mortality and morbidity due to cardiovascular disease (CVD). In this prospective 5-year follow up of patients with RA, we analysed several biomarkers, known to be associated with atherosclerosis and/or inflammation in the general population. The aim of this study was to find out whether the RA-disease per se affect these biomarkers and if those could be associated with the progression of atherosclerosis, as measured by intima media thickness (IMT) among patients with early RA. METHODS: Patients from northern Sweden diagnosed with early RA, are consecutively recruited into an ongoing prospective study on CVD comorbidity. A subgroup of patients, aged ≤60 years (n = 71) was included for ultrasound measurements of IMT at inclusion (T0) and after 5 years (T5) together with age-sex-matched controls (n = 40). The patients were clinically assessed. Blood was analysed for lipids, ESR and CRP and several biomarkers known to be associated with atherosclerosis in the general population. RESULTS: At T0, the patients with RA had significantly lower levels of MIF and significantly higher levels of interleukin (IL)-18 and MIC-1 compared with controls. At T5, the patients with RA had significantly higher levels of pentraxin3, MIC-1, TNF-R2, ICAM-1, VCAM-1 and endostatin compared with controls. At T0 the levels of MPO correlated with DAS28, sCD40L with CRP and IL-18 with systolic blood pressure and Reynolds risk score. Using PLSR on a CVD-panel analysed with multiplex immunoassay, the patients with RA could be correctly classified into those who had a worsening in their IMT over the five years or not. Here, MMP3 was identified as influential. CONCLUSIONS: This study indicates that the RA disease itself could affect several of the biomarkers in this study, and possibly also the processes involved in the development of atherosclerosis.

Platelet function testing at low platelet counts: When can you trust your analysis?

BACKGROUND: Although flow cytometry is often brought forward as a preferable method in the setting of thrombocytopenia, the relative effects of low sample counts on results from flow cytometry-based platelet function testing (FC-PFT) in comparison with light transmission aggregometry (LTA) and multiple electrode aggregometry (MEA) has not been reported. OBJECTIVES: To compare the effects of different sample platelet counts (10, 50, 100, and 200 × 109 L-1) on platelet activation measured with FC-PFT, LTA, and MEA using the same anticoagulant and agonist concentrations as for the commercial MEA test. METHODS: Platelets were stimulated with two commonly used platelet agonists (ADP [6.5 µmol L-1] and PAR1-AP [TRAP, 32 µmol L-1]). The specified sample platelet counts were obtained by combining platelet-rich and platelet poor hirudinized plasma in different proportions with or without red blood cells. RESULTS: For FC, P-selectin exposure and PAC-1 binding was reduced at 10 × 109 L-1 after stimulation with PAR1-AP (by approximately 20% and 50%, respectively), but remained relatively unchanged when ADP was used as agonist (n = 9). The platelet count-dependent effects observed with PAR1-AP were eliminated when samples were pre-incubated with apyrase, implying that reduced purinergic signaling was the main underlying factor (n = 5). Both aggregometry-based PFTs showed a 50% reduction at 50 × 109 L-1 and more than 80% reduction at 10 × 109 L-1, irrespective of agonist used (n = 7). CONCLUSIONS: Although FC-PFT is generally preferable to aggregometry-based PFTs in situations with low sample platelet counts, a careful optimization of experimental parameters is still required in order to eliminate platelet count-related effects.

Platelet subpopulations remain despite strong dual agonist stimulation and can be characterised using a novel six-colour flow cytometry protocol.

It is recognised that platelets respond differently to activation, where a subpopulation of platelets adopt a procoagulant phenotype while others are aggregatory. However, it has not been thoroughly tested whether these subpopulations will remain in maximally activated samples, or if they are merely a result of different platelet sensitivities to agonist activation. Here platelets were activated with gradually increasing concentrations of thrombin and/or the GPVI agonist cross-linked collagen-related peptide (CRP-XL). Platelet activation was investigated using a novel six-colour flow cytometry protocol evaluating exposure of phosphatidylserine, active conformation of the fibrinogen receptor αIIbß3, α-granule and lysosomal release (P-selectin and LAMP-1 exposure), mitochondrial membrane integrity and platelet fragmentation. Upon activation by CRP-XL or thrombin+CRP-XL, platelets formed three differently sized subpopulations. Normal-sized platelets showed high exposure of aggregatory active αIIbß3 and intact mitochondria, while the smaller platelets and platelet fragments showed high exposure of procoagulant phosphatidylserine. The distribution of platelets between the differently sized subpopulations remained stable despite high agonist concentrations. All three were still present after 30 and 60 min of activation, showing that all platelets will not have the same characteristics even after maximal stimulation. This suggests that platelet subpopulations with distinct activation patterns exist within the total platelet population.

Detection of Lysosomal Exocytosis in Platelets by Flow Cytometry.

Flow cytometry is a method that allows high throughput analysis of individual cells in suspension. By inclusion of fluorescently labelled antibodies, it is possible to analyze the abundance of one or more surface antigens, such as LAMP-1, without prior lysis of cells. Here we describe the special considerations required for the investigation of lysosomal exocytosis from platelets analyzed with flow cytometry.

High Concentrations of Angiopoietin-Like Protein 4 Detected in Serum from Patients with Rheumatoid Arthritis Can Be Explained by Non-Specific Antibody Reactivity.

Angiopoietin-like protein 4 (ANGPTL4) is suggested to be a master regulator of plasma triglyceride metabolism. Our aim was to study whether the previously reported high levels of ANGPTL4 detected in serum from patients with rheumatoid arthritis (RA) by ELISA was due to any specific molecular form of this protein (oligomers, monomers or fragments). ANGPTL4 levels were first determined in serum from 68 RA patients and 43 age and sex matched control subjects and the mean values differed by a factor of 5.0. Then, ANGPTL4 was analyzed after size exclusion chromatography (SEC) of serum samples. With serum from one of the RA patients with high levels of ANGPTL4, the dominant reactivity was found in fractions corresponding to high-molecular weight proteins. In addition, a minor peak of reactivity eluting late from the column was found both in the patient and in controls. By the use of HeteroBlock®, and by careful selection of antibodies, we documented non-specific reactions for ANGPTL4 in 39% of samples from the RA patients, most likely due to cross-reactivity of the antibodies with rheumatoid factor (RF). The corresponding figure for control subjects was 6.3%. After corrections for non-specific reactions, the mean level of ANGPTL4 in serum from RA patients was still significantly higher than in control individuals (mean levels were 101±62 and 67±39 ng/ml respectively, P = 0.02). We re-analyzed samples from our previously published studies on ANGPL4 levels in patients on hemodialysis and patients with diabetes type 2. These samples did not show false positive reactions. The levels of ANGPTL4 were comparable to those detected previously.

Platelet Function Determined by Flow Cytometry: New Perspectives?

Flow cytometry enables studies of several different aspects of platelet function in response to a variety of platelet agonists. This can be done using only a small volume of whole blood, and also in blood with low platelet counts. These properties, together with the increasing number of flow cytometers available in hospitals worldwide, make flow cytometry an interesting option for laboratories interested in studies of platelet function in different clinical settings. This review focuses on practical issues regarding the use of flow cytometry for platelet function testing. It provides an overview of available activation markers, platelet agonists, and experimental setup issues. The review summarizes previous experience and factors important to consider to perform high-quality platelet function testing by flow cytometry. It also discusses its current use and possibilities and challenges for future use of flow cytometry in clinical settings.

Co-morbidity in patients with early rheumatoid arthritis - inflammation matters.

BACKGROUND: Patients with rheumatoid arthritis (RA) suffer from co-morbidities that contribute to a shortened lifespan. Inflammation is important for the development of cardiovascular disease, but little is known on its relationship with other co-morbidities. We investigated the role of inflammation for the development of new comorbidities in early RA. METHODS: Since 1995, all patients with early RA in Northern Sweden are included in a prospective study on co-morbidities, with a total of 950 patients being included. At the time for this study, 726 had been ill for ≥5 years. Data on co-morbidities, clinical and laboratory disease activity and pharmacological therapy were collected from patient records and further validated using a questionnaire at RA onset (T0) and after 5 years (T5). RESULTS: Of the patients, 53.2 % of the patients had one or more co-morbidity at onset, the commonest being: hypertension (27.3 %), obstructive pulmonary disease (13.9 %), diabetes (8.0 %), hypothyroidism (6.3 %) and malignancy (5.0 %). After 5 years, 41.0 % had developed at least one new co-morbidity, the most common being: hypertension (15.1 %), malignancy (7.6 %), stroke/transient ischemic accident (5.1 %), myocardial infarction (4.3 %) and osteoporosis (3.7 %). Age at disease onset, a raised erythrocyte sedimentation rate (ESR) at inclusion, previous treatment with glucocorticoids (GC; p < 0.001 for all), extra-articular RA (Ex-RA; p < 0.01), DAS28 (area under the curve) at 24 months (p < 0.05), previous smoking at inclusion (p = 0.058) and male gender (p < 0.01) were associated with a new co-morbidity overall at T5. Treatment with biologics (p < 0.05) reduced the risk. In multiple logistic regression modelling, ESR (p = 0.036) at inclusion was associated with a new co-morbidity after 5 years, adjusted for age, sex, smoking and GC treatment. In a similar model, Ex-RA (p < 0.05) was associated with a new co-morbidity at T5. In a third model, adjusted for age and sex, a new pulmonary co-morbidity was associated with a smoking history at inclusion (p < 0.01), but not with ESR. CONCLUSION: There was substantial co-morbidity among early RA patients already at disease onset, with considerable new co-morbidity being added during the first five years. Measures of disease activity were associated with the occurrence of a new co-morbidity indicating that the inflammation is of importance in this context.

Thrombin-induced lysosomal exocytosis in human platelets is dependent on secondary activation by ADP and regulated by endothelial-derived substances.

Exocytosis of lysosomal contents from platelets has been speculated to participate in clearance of thrombi and vessel wall remodelling. The mechanisms that regulate lysosomal exocytosis in platelets are, however, still unclear. The aim of this study was to identify the pathways underlying platelet lysosomal secretion and elucidate how this process is controlled by platelet inhibitors. We found that high concentrations of thrombin induced partial lysosomal exocytosis as assessed by analysis of the activity of released N-acetyl-ß-glucosaminidase (NAG) and by identifying the fraction of platelets exposing the lysosomal-associated membrane protein (LAMP)-1 on the cell surface by flow cytometry. Stimulation of thrombin receptors PAR1 or PAR4 with specific peptides was equally effective in inducing LAMP-1 surface expression. Notably, lysosomal exocytosis in response to thrombin was significantly reduced if the secondary activation by ADP was inhibited by the P2Y12 antagonist cangrelor, while inhibition of thromboxane A2 formation by treatment with acetylsalicylic acid was of minor importance in this regard. Moreover, the NO-releasing drug S-nitroso-N-acetyl penicillamine (SNAP) or the cyclic AMP-elevating eicosanoid prostaglandin I2 (PGI2) significantly suppressed lysosomal exocytosis. We conclude that platelet inhibitors that mimic functional endothelium such as PGI2 or NO efficiently counteract lysosomal exocytosis. Furthermore, we suggest that secondary release of ADP and concomitant signaling via PAR1/4- and P2Y12 receptors is important for efficient platelet lysosomal exocytosis by thrombin.