The effect of various stimuli and calcium antagonists on the fluorescence response of chlorotetracycline-loaded human neutrophils

Chlorotetracycline has been used in neutrophils and other cells as probe of the state of membrane-bound calcium. We report here that human neutrophils treated with chlorotetracycline response to soluble secretagogues by a prompt decrease in chlorotetracycline fluorescence. This response was observed within 2-5 s, making it one of the most immediate reactions in neutrophils to stimulation, and was obtained with three secretagogues studied: a chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine, a tumor promotor (phorbol myristate acetate) and a lectin (concanavalin A). The responses of neutrophils to the three stimuli differed both quantitatively and qualitatively. The calcium EGTA, did not effect the onset of the decrease in chlorotetracycline fluorescence, suggesting that the probe was measuring changes in intracellular calcium pools. The intracellular calcium antagonists, TMb-8, W-7 and trifluoperazine, did not block, but actually augmented, the fluorescence response. All four of these calcium antagonists blocked the recovery of chlorotetracycline fluorescence which was usually observed several minutes after stimulation with N-formyl-methionyl-leucyl-phenylalanine. This suggests that recovery was dependent upon both extracellular calcium and active calmodulin. The results are consistent with the hypothesis that changes in chlorotetracycline fluorescence reflect changes in a pool of membrane-bound 'trigger calcium', the release of which is an essential first step in stimulus-response coupling in human neutrophils.     

Slow voltage inactivation of Ca2+ currents and bursting mechanisms for the mouse pancreatic beta-cell

Summary Recent whole-cell electrophysiological data concerning the properties of the Ca²⁺ currents in mouse -cells are fitted by a two-current model of Ca²⁺ channel kinetics. When the -cell K⁺ currents are added to this model, only large modifications of the measured Ca²⁺ currents will reproduce the bursting pattern normally observed in mouse islets. However, when the measured Ca²⁺ currents are modified only slightly and used in conjunction with a K⁺ conductance that can be modulated dynamically by ATP concentration, reasonable bursting is obtained. Under these conditions it is the K-ATP conductance, rather than the slow voltage inactivation of the Ca²⁺ current, that determines the interburst interval. We find that this latter model can be reconciled with experiments that limit the possible periodic variation of the K-ATP conductance and with recent observations of intracellular Ca²⁺ bursting in isletsThis work was supported in part by NSF grant DIR-90-06104 and the Agricultural Experiment Station of the University of California. P.S. gratefully acknowledges financial support from an NRC Fellowship. We have benefited from numerous conversations with Drs. John Rinzel, Arthur Sherman, Daniel Cook, and Leslie Satin     

A Combination of CD28 (rs1980422) and IRF5 (rs10488631) Polymorphisms Is Associated with Seropositivity in Rheumatoid Arthritis: A Case Control Study

IntroductionThe aim of the study was to analyse genetic architecture of RA by utilizing multiparametric statistical methods such as linear discriminant analysis (LDA) and redundancy analysis (RDA).MethodsA total of 1393 volunteers, 499 patients with RA and 894 healthy controls were included in the study. The presence of shared epitope (SE) in HLA-DRB1 and 11 SNPs (PTPN22 C/T (rs2476601), STAT4 G/T (rs7574865), CTLA4 A/G (rs3087243), TRAF1/C5 A/G (rs3761847), IRF5 T/C (rs10488631), TNFAIP3 C/T (rs5029937), AFF3 A/T (rs11676922), PADI4 C/T (rs2240340), CD28 T/C (rs1980422), CSK G/A (rs34933034) and FCGR3A A/C (rs396991), rheumatoid factor (RF), anti–citrullinated protein antibodies (ACPA) and clinical status was analysed using the LDA and RDA.ResultsHLA-DRB1, PTPN22, STAT4, IRF5 and PADI4 significantly discriminated between RA patients and healthy controls in LDA. The correlation between RA diagnosis and the explanatory variables in the model was 0.328 (Trace = 0.107; F = 13.715; P = 0.0002). The risk variants of IRF5 and CD28 genes were found to be common determinants for seropositivity in RDA, while positivity of RF alone was associated with the CTLA4 risk variant in heterozygous form. The correlation between serologic status and genetic determinants on the 1st ordinal axis was 0.468, and 0.145 on the 2nd one (Trace = 0.179; F = 6.135; P = 0.001). The risk alleles in AFF3 gene together with the presence of ACPA were associated with higher clinical severity of RA.ConclusionsThe association among multiple risk variants related to T cell receptor signalling with seropositivity may play an important role in distinct clinical phenotypes of RA. Our study demonstrates that multiparametric analyses represent a powerful tool for investigation of mutual relationships of potential risk factors in complex diseases such as RA.     

Cytokine regulation of apoptosis and Bcl-2 expression in lymphocytes of patients with systemic lupus erythematosus

Both faulty regulation of apoptosis and the inappropriate expression of several interleukins have been considered important defects of lymphocytes in the human autoimmune disease systemic lupus erythematosus (SLE). We therefore tested the in vitro effect of recombinant interleukin (IL-)-2, 4, 7, and 15 on peripheral blood mononuclear cells from patients with SLE and from healthy volunteers. Intracellular Bcl-2 and Bax expression was measured by fluorocytometry and the rate of apoptosis was determined by the TUNEL technique and propidium iodide staining. IL-2, IL-4, IL-7 and IL-15 led to a significant increase in Bcl-2 and a reduction in cell death rates, which was even more pronounced in SLE. Bax levels remained unchanged. Interestingly, the high ex vivo Bcl-2 content of lymphocytes from some SLE patients was maintained after growth factor withdrawal. Anti-apoptotic cytokine signaling may significantly influence the deregulation of cell death in SLE lymphocytes.     

Gait changes precede overt arthritis and strongly correlate with symptoms and histopathological events in pristane-induced arthritis

Introduction  

Pristane-induced arthritis (PIA) in the rat has been described as an animal model of inflammatory arthritis which exhibits features similar to rheumatoid arthritis in humans, such as a chronic, destructive, and symmetrical involvement of peripheral joints. However, so far little is known about the earliest inflammatory events and their influence on locomotor behaviour during the course of PIA. To investigate this issue a detailed analysis of the pathologic changes occurring during the prodromal and early stages of PIA was performed.     

The impact of infliximab treatment on quality of life in patients with inflammatory rheumatic diseases

In this study, we compare the health-related quality of life (HRQoL) of patients with moderate-to-severe rheumatoid arthritis (RA), psoriatic arthritis (PsA), and ankylosing spondylitis (AS), and study the effect of treatment with infliximab on the HRQoL of patients with these diseases. Short Form Health Survey-36 (SF-36) data from the placebo-controlled phases of 4 studies of infliximab in patients with inflammatory rheumatic diseases (n = 1990) were evaluated. Data came from the Anti-TNF Trial in Rheumatoid Arthritis with Concomitant Therapy (ATTRACT) (n = 428), the Safety Trial for Rheumatoid Arthritis with REMICADE Therapy (START) (n = 1083), the Ankylosing Spondylitis Study for the Evaluation of Recombinant Infliximab Therapy (ASSERT) (n = 279), and the Infliximab Multinational Psoriatic Arthritis Clinical Trial II (IMPACT II) (n = 200). SF-36 assessments were made at weeks 0, 10, 30, and 54 in ATTRACT, weeks 0, 6, and 22 in START, weeks 0, 12, and 24 in ASSERT, and weeks 0 and 14 in IMPACT II. All patient populations had significantly impaired physical aspects of HRQoL at baseline relative to the general population of the United States, and the magnitude of impairment was similar across the diseases. Mean baseline physical component summary scores were 29 in the RA cohort, 32 in the PsA cohort, and 29 in the AS cohort. In all 3 diseases, patients who received infliximab showed significant improvement in physical component summary scores compared with those who received placebo. The magnitude of the difference of improvement (effect size, 95%CI) between infliximab and placebo groups was similar in the AS (10.1, 9.2–11.0), PsA (8.6, 7.8–9.4), and RA (10.1, 9.2–11.0) cohorts. Patients with RA and those with PsA treated with infliximab also showed greater improvement in the mental component summary score than those in the placebo group with an effect size of 4.6 (4.2–5.1) in RA and 2.7 (2.4–3.1) in PsA. Patients in large randomized controlled studies of infliximab in RA, PsA, and AS had similar impairment in physical aspects of HRQoL at baseline and showed significantly greater improvement in HRQoL after treatment with infliximab.     

Certolizumab pegol plus methotrexate 5-year results from the rheumatoid arthritis prevention of structural damage (RAPID) 2 randomized controlled trial and long-term extension in rheumatoid arthritis patients

IntroductionAs patients with rheumatoid arthritis (RA) receive treatment with anti-tumour necrosis factors over several years, it is important to evaluate their long-term safety and efficacy. The objective of this study was to examine the safety and benefits of certolizumab pegol (CZP)+methotrexate (MTX) treatment for almost 5 years in patients with RA.MethodsPatients who completed the 24-week Rheumatoid Arthritis Prevention of Structural Damage (RAPID) 2 randomized controlled trial (RCT; {"type":"clinical-trial","attrs":{"text":"NCT00160602","term_id":"NCT00160602"}}NCT00160602), or who were American College of Rheumatology (ACR) 20 non-responders at Week 16, entered the open-label extension (OLE; {"type":"clinical-trial","attrs":{"text":"NCT00160641","term_id":"NCT00160641"}}NCT00160641). After ≥6 months treatment with CZP 400 mg every two weeks (Q2W), dose was reduced to 200 mg Q2W, the approved maintenance dose. Safety data are presented from all patients who received ≥1 dose CZP (Safety population, n=612). Efficacy data are presented to Week 232 for the intent-to-treat (ITT, n=492) and Week 24 CZP RCT Completer (n=342) populations, and through 192 weeks of dose-reduction for the Dose-reduction population (patients whose CZP dose was reduced to 200 mg, n=369). Radiographic progression (modified total Sharp score change from RCT baseline >0.5) to Week 128 is reported for the Week 24 CZP Completers.ResultsIn the RCT, 619 patients were randomized to CZP+MTX (n=492) or placebo+MTX (n=127). Overall, 567 patients (91.6%) entered the OLE: 447 CZP and 120 placebo patients. Of all randomized patients, 358 (57.8%) were ongoing at Week 232. Annual drop-out rates during the first four years ranged from 8.4–15.0%. Event rates per 100 patient-years were 163.0 for adverse events (AEs) and 15.7 for serious AEs. Nineteen patients (3.1%) had fatal AEs (incidence rate=0.8). Clinical improvements in the RCT were maintained to Week 232 in the CZP Completers: mean Disease Activity Score 28 (Erythrocyte Sedimentation Rate) change from baseline was −3.4 and ACR20/50/70 responses 68.4%/47.1%/25.1% (non-responder imputation). Similar improvements observed in the ITT were maintained following dose-reduction. 73.2% of CZP Completers had no radiographic progression at Week 128.ConclusionsIn patients with active RA despite MTX therapy, CZP was well tolerated, with no new safety signals identified. CZP provided sustained improvements in clinical outcomes for almost 5 years.

Trial registration

ClinicalTrials.gov, {"type":"clinical-trial","attrs":{"text":"NCT00160602","term_id":"NCT00160602"}}NCT00160602 and {"type":"clinical-trial","attrs":{"text":"NCT00160641","term_id":"NCT00160641"}}NCT00160641. Registered 8 September 2005.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-015-0767-2) contains supplementary material, which is available to authorized users.