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Cholesterol efflux capacity (CEC), the ability of high-density lipoprotein (HDL) cholesterol to accept cholesterol from macrophages, has been linked to cardiovascular events. Systemic lupus erythematosus (SLE) is characterized by the consumption of complement (C) proteins and has been associated with an increased risk of cardiovascular disease. CEC is reduced in SLE patients compared to controls. In the present work, our objective was to analyze whether the disruption of C influences CEC in patients with SLE. New-generation functional assays of the three pathways of the C system were performed in 207 patients with SLE. Additionally, serum levels of inactive (C1q, C2, C3, C4, and factor D) and activated (C3a) molecules, and regulators (C1-inhibitor and factor H) of C system were measured. CEC, using an in vitro assay, and lipoprotein serum concentrations were assessed. Multivariable linear regression analysis was performed to assess the relationship between C system and CEC. After full multivariable analysis, the alternative C cascade functional test showed a significant and negative relationship with CEC. This was also the case for C2 and C3, in which the associations were found to be positive and statistically significant, after adjustment for covariates. In conclusion, C system and CEC are interconnected in patients with SLE. [ABSTRACT FROM AUTHOR]

Background: To date a complete characterization of the components of the complement (C) pathways (CLassical, LEctin and ALternative) in patients with systemic lupus erythematosus (SLE) has not been performed. We aimed to assess the function of these three C cascades through functional assays and the measurement of individual C proteins. We then studied how they relate to clinical characteristics. Methods: New generation functional assays of the three pathways of the C system were assessed in 284 patients with SLE. Linear regression analysis was performed to study the relationship between the activity, severity, and damage of the disease and C system. Results: Lower values of the functional tests AL and LE were more frequent than those of the CL pathway. Clinical activity was not related to inferior values of C routes functional assays. The presence of increased DNA binding was negatively linked to all three C pathways and products, except for C1-inh and C3a which were positively related. Disease damage revealed a consistent positive, rather than a negative, relationship with pathways and C elements. Anti-ribosomes and anti-nucleosomes were the autoantibodies that showed a greater relationship with C activation, mainly due to the LE and CL pathways. Regarding antiphospholipid antibodies, the most related with C activation were IgG antib2GP, predominantly involving the AL pathway. Conclusion: Not only the CL route, but also the AL and LE are related to SLE features. C expression patterns are linked to disease profiles. While accrual damage was associated with higher functional tests of C pathways, anti-DNA, anti-ribosomes and anti-nucleosomes antibodies, were the ones that showed a higher relationship with C activation, mainly due to the LE and CL pathways. [ABSTRACT FROM AUTHOR]

Objective: Cholesterol efflux capacity (CEC) is the ability of high‐density lipoprotein (HDL) cholesterol to accept cholesterol from macrophages. Lipid profiles and CEC appear to be altered in patients with systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) due to disease activity and inflammation. CEC has been linked to cardiovascular events in the general population and to subclinical atherosclerosis in SLE and RA patients. The aim of this study was to establish whether CEC varies between patients with SLE and those with RA. Methods: The study encompassed 460 individuals (195 SLE patients and 265 patients with RA). CEC (using an in vitro assay) and concentrations of lipoprotein serum were assessed in both populations. A multivariable regression analysis was performed to study whether CEC differs between SLE patients and RA patients. Results: Comparison of lipid patterns revealed that patients with RA have lower HDL cholesterol and higher apolipoprotein B serum levels than SLE patients. CEC was downregulated in SLE patients compared to patients with RA (β –12 [95% confidence interval –13, –10], P < 0.001). It occurred independently of traditional cardiovascular risk factors, statin use, disease‐related data, and other variations in the lipid profile related to the diseases. Conclusion: Patients with RA have a more proatherogenic lipid pattern compared to those with SLE. However, CEC seems to be more damaged in SLE patients than in RA patients. [ABSTRACT FROM AUTHOR]

Objectives Lipid profiles appear to be altered in SLE patients due to disease activity and inflammation. Cholesterol efflux capacity (CEC) is the ability of high-density lipoprotein cholesterol to accept cholesterol from macrophages. CEC has been linked to cardiovascular events in the general population and is impaired in SLE patients. The aim of this study was to establish whether CEC is related to subclinical carotid atherosclerosis in SLE patients. Methods The present report is of a cross-sectional study that encompassed 418 individuals: 195 SLE patients and 223 controls. CEC, using an in vitro assay, and lipoprotein serum concentrations were assessed in patients and controls. Carotid intima-media thickness and carotid plaques were evaluated in SLE patients. A multivariable analysis was performed to study the relationship of CEC to SLE-related data, lipid profile and subclinical carotid atherosclerosis. Results CEC was downregulated in SLE patients [8.1  (4.2) % vs 16.9 (10.4) %, P = 0.004). This occurred independently of traditional cardiovascular risk factors, statin use or other variations in the lipid profile related to the disease. Traditional cardiovascular risk factors, both in patients and controls, and SLE-related data such as activity, severity or damage were not associated with CEC. After multivariable regression analysis including lipid profile–related molecules, CEC was inversely and independently associated with the presence of carotid plaques in SLE patients [odds ratio 0.87 (95% CI: 0.78, 0.97), P = 0.014]. Conclusion CEC is impaired in SLE patients independently of other inflammation-related lipid profile modifications that occur during the disease. CEC is associated with carotid plaques in SLE patients. [ABSTRACT FROM AUTHOR]

Objectives Prevalence of SLE varies among studies, being influenced by study design, geographical area and ethnicity. Data about the prevalence of SLE in Spain are scarce. In the EPISER2016 study, promoted by the Spanish Society of Rheumatology, the prevalence estimate of SLE in the general adult population in Spain has been updated and its association with sociodemographic, anthropometric and lifestyle variables has been explored. Methods Population-based multicentre cross-sectional study, with multistage stratified and cluster random sampling. Participants were contacted by telephone to carry out a questionnaire for the screening of SLE. Investigating rheumatologists evaluated positive results (review of medical records and/or telephone interview, with medical visit if needed) to confirm the diagnosis. To calculate the prevalence and its 95% CI, the sample design was taken into account and weighing was calculated considering age, sex and geographic origin. Multivariate logistic regression models were defined to analyse which sociodemographic, anthropometric and lifestyle variables included in the telephone questionnaire were associated with the presence of SLE. Results 4916 subjects aged 20 years or over were included. 16.52% (812/4916) had a positive screening result for SLE. 12 cases of SLE were detected. The estimated prevalence was 0.21% (95% CI: 0.11, 0.40). SLE was more prevalent in the rural municipalities, with an odds ratio (OR) = 4.041 (95% CI: 1.216, 13.424). Conclusion The estimated prevalence of SLE in Spain is higher than that described in most international epidemiological studies, but lower than that observed in ethnic minorities in the United States or the United Kingdom. [ABSTRACT FROM AUTHOR]

Objective: The prevalence of psoriatic arthritis (PsA) is very heterogeneous. There are no data on its frequency in the general population in Spain. The aim of EPISER2016 study was to estimate the prevalence of PsA in people aged ≥20 years in Spain. Methods: Cross-sectional multicenter population-based study. Subjects from all the autonomous communities in Spain were randomly selected using multistage stratified cluster sampling. Participants in each of the municipalities randomly selected for the study were administered a telephone-based questionnaire to screen for the study diseases. If the participant reported being previously diagnosed, rheumatologists from the participant's reference hospital confirmed the diagnosis based on a review of the clinical history. Subjects not previously diagnosed but whose screening result was positive based on symptoms received a second telephone call from the investigating rheumatologist in order to evaluate the suspicion. If the suspicion remained, an appointment was made at the reference hospital to complete the diagnostic confirmation process according to CASPAR criteria. To calculate the prevalence and its 95% confidence interval (CI), the sample design was taken into account and weighing was calculated considering age, sex and geographic origin. Results: The sample comprised 4916 subjects. The prevalence of PsA was 0.58% (95%CI: 0.38–0.87). All but 1 of the 27 cases (96.30%) had been diagnosed prior to EPISER2016. Conclusion: The prevalence of PsA in Spain was among the highest reported to date, only below that reported in Norway (0.67%) and slightly higher than that reported in Italy (0.42%). [ABSTRACT FROM AUTHOR]

The use of vitamin D (VitD) supplements has become widespread in the last decade due not only to the dissociation between the blood levels recommended as "optimal" and those shown by the healthy population but also to its presumed beneficial effects on multiple disorders. This work evaluated the levels of 25-hydroxyvitamin D (25(OH)D) in a healthy population of European origin living in a region with high solar irradiation. In serum samples from a population-based study conducted in the Canary Islands, levels of 25(OH)D were analyzed. In 876 individuals who had no history of kidney or malabsorption disorders and, who had not been treated with calcium and/or VitD supplementation, the median 25(OH)D level was 26.3 (5th; 95th percentile, 14.3; 45.8) ng/mL. Notably, 65.4% of the population had 25(OH)D blood levels below 30 ng/mL, 23.4% below 20 ng/mL and 6.4% below 15 ng/mL. Based on the lack of evidence supporting causality between 25(OH)D levels below what is recommended as optimal (≥20 ng/mL, or even ≥30 ng/mL) and major skeletal and non-skeletal diseases, and in light of the distribution of the concentration of this vitamin in healthy adults living under optimal conditions of solar irradiation, it seems reasonable to consider 25(OH)D levels below 20 ng/mL and close to 15 ng/mL as adequate for the general population. [ABSTRACT FROM AUTHOR]

Background: Tumor necrosis factor alpha (TNFα) may act as a link between inflammation and cardiovascular disease through several effects including the induction of insulin resistance (IR). The purpose of this study was to clarify if long-term modulation of inflammatory activity by TNFα inhibitors in RA patients has some influence on insulin sensitivity.Methods: Sixteen RA patients treated with anti-TNFα agents were followed during one year. Disease activity was assessed by DAS28, IR was determined by using Homeostatic Model Assessment-2, body composition was evaluated by impedance analysis, physical activity by accelerometry, abdominal fat distribution by magnetic resonance imaging, and serum level of key adipokines were quantified by ELISA.Results: Body mass indices were increased significantly after one year (25.71±3.20 vs 28.06±4.57 kg/m2, p=0.02) of treatment. Body composition interms of fat and fat-free mass had not changed except for a significant elevation of body cell mass (25.50±4.60 vs 26.60±3.17 kg, p=0.02). Values of visceral intraabdominal and subcutaneous abdominal adipose tissue were not modified. Levels of IR, beta cell production or insulin sensitivity did not change along the study. Basal levels of adiponectin, visfatin, leptin, ghrelin, resistin, and apelin did not change in response to anti-TNFα treatment; only retinol binding protein 4 showed a significant change (51.7±32.7 vs 64.9±28.4 μg/mL, p=0.03) at the end of the study.Conclusions: Insulin resistance, adiposity distribution, body composition, andserum levels of adipokines are not significantly affected by long-term inhibitionof TNFα in RA patients. Our findings question the suggested beneficial role ofanti-TNFα treatments in insulin resistance. [ABSTRACT FROM AUTHOR]

Background: The early identification of patients' profiles most likely to respond to and maintain long-term therapy with a biological drug can have clinical and cost-effectiveness implications., Objectives: To evaluate the utility of an innovative approach for early identification of patient profiles associated with long-term persistence of golimumab, a tumour necrosis factor inhibitor, in patients with rheumatoid arthritis (RA), psoriatic arthritis (PsA), and axial spondyloarthritis (SpA) under real-world conditions., Design: Retrospective non-interventional database analysis., Methods: Kaplan-Meier curves of golimumab retention over 8 years from the BIOBADASER registry, overall and by indication, were analysed using a novel approach (a two-phase decay model) to identify the point at which the golimumab retention curve shifted from rapid (indicating high golimumab discontinuation rate) to slow decay (low discontinuation rate). Factors associated with golimumab retention at these time points were identified using Cox regression, and retention rates for different patient profiles were calculated., Results: 885 patients were included. The golimumab retention curve shifted from rapid to slow decay at month 10 for the overall population (retention rate: 73.4%), at month 24 for RA patients (retention: 45.0%), and at month 8 for SpA, including axial SpA and PsA (81.6%). Factors associated with golimumab discontinuation at these early points were, overall, similar to those previously identified at year 8 (RA diagnosis, golimumab as second- or third-line of biological therapy, disease activity over the median and treatment with corticosteroids at golimumab initiation, advanced age [in RA], and female gender [in SpA])., Conclusion: With this novel approach, the factors associated with long-term retention were identified in the initial period of rapid discontinuation of golimumab., Competing Interests: MS-J and LC-C: full-time employee at MSD, Spain. MP-S: consulting honorarium from Janssen and MSD; lectures for Janssen, MSD and Novartis. IC: consulting honorarium from Pfizer and Galapagos; lectures for BMS, GSK, Lilly, Pfizer, MSD and Janssen. FD-G: consulting fees from AbbVie, Lilly, Pfizer, Galapagos; for conferences from Janssen, Galapagos, AbbVie, Novartis; and for financial aid to research from Janssen, Novartis, MSD and AbbVie. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The reviewer AO declared a shared parent affiliation with the author IC to the handling editor at the time of review., (Copyright © 2024 García-Dorta, González-Dávila, Sánchez-Jareño, Cea-Calvo, Pombo-Suárez, Sánchez-Alonso, Castrejón and Díaz-González.)

Background: Secukinumab has been shown effective for psoriatic arthritis (PsA) and axial spondylarthritis (AxSpA) in randomized trials. The aim of this study was to analyze baseline patient and disease characteristics associated with a better retention rate of secukinumab under real-world conditions. Patients and Methods: Real-life, prospective multicenter observational study involving 138 patients, 61 PsA and 77 AxSpA, who were analyzed at baseline, 6, 12 months and subsequently every year after starting secukinumab regardless of the line of treatment. Demographics and disease characteristics, measures of activity, secukinumab use, and adverse events were collected. Drug survival was analyzed using Kaplan-Meier curves and factors associated with discontinuation were evaluated using Cox regression. The machine-learning J48 decision tree classifier was also applied. Results: During the 1st year of treatment, 75% of patients persisted with secukinumab, but accrued 71% ( n = 32) in total losses ( n = 45). The backward stepwise (Wald) method selected diagnosis, obesity, and gender as relevant variables, the latter when analyzing the interactions. At 1 year of follow-up, the Cox model showed the best retention rate in the groups of AxSpa women (95%, 95% CI 93-97%) and PsA men (89%, 95% CI 84-93%), with the worst retention in PsA women (66%, 95% CI 54-79%). The J48 predicted secukinumab retention with an accuracy of 77.2%. No unexpected safety issues were observed. Conclusions: Secukinumab shows the best retention rate at 1 year of treatment in AxSpA women and in PsA men, independently of factors such as the time of disease evolution, the line of treatment or the initial dose of the drug., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 García-Dorta, León-Suarez, Peña, Hernández-Díaz, Rodríguez-Lozano, González-Dávila, Hernández-Hernández and Díaz-González.)

Objectives: Prevalence of SLE varies among studies, being influenced by study design, geographical area and ethnicity. Data about the prevalence of SLE in Spain are scarce. In the EPISER2016 study, promoted by the Spanish Society of Rheumatology, the prevalence estimate of SLE in the general adult population in Spain has been updated and its association with sociodemographic, anthropometric and lifestyle variables has been explored., Methods: Population-based multicentre cross-sectional study, with multistage stratified and cluster random sampling. Participants were contacted by telephone to carry out a questionnaire for the screening of SLE. Investigating rheumatologists evaluated positive results (review of medical records and/or telephone interview, with medical visit if needed) to confirm the diagnosis. To calculate the prevalence and its 95% CI, the sample design was taken into account and weighing was calculated considering age, sex and geographic origin. Multivariate logistic regression models were defined to analyse which sociodemographic, anthropometric and lifestyle variables included in the telephone questionnaire were associated with the presence of SLE., Results: 4916 subjects aged 20 years or over were included. 16.52% (812/4916) had a positive screening result for SLE. 12 cases of SLE were detected. The estimated prevalence was 0.21% (95% CI: 0.11, 0.40). SLE was more prevalent in the rural municipalities, with an odds ratio (OR) = 4.041 (95% CI: 1.216, 13.424)., Conclusion: The estimated prevalence of SLE in Spain is higher than that described in most international epidemiological studies, but lower than that observed in ethnic minorities in the United States or the United Kingdom., (© The Author(s) 2020. Published by Oxford University Press on behalf of the British Society for Rheumatology.)

Objectives: Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a serine protease that regulates cholesterol metabolism through low-density lipoprotein receptor degradation, and which has been linked to cardiovascular risk. The purpose of the present study was to examine whether PCSK9 serum levels are disrupted in patients with systemic sclerosis (SS) compared to controls, and if PCSK9 is related to disease-related data and the subclinical atherosclerosis that occurs in these patients., Methods: Cross-sectional study that encompassed 146 individuals; 73 patients with SS and 73 age- and sex-matched controls. PCSK9, lipoproteins serum concentrations, and standard lipid profiles were assessed in patients and controls. Carotid intima-media thickness (cIMT) and the presence of carotid plaques were evaluated in SS patients. A multivariable analysis, adjusted for traditional cardiovascular risk factors, was performed to evaluate the differences in PCSK9 between patients and controls, the association of SS-related manifestations with PCSK9 levels, and if PCSK9 was associated with subclinical carotid atherosclerosis in SS patients., Results: After multivariable analysis, PCSK9 was downregulated in SS patients compared to controls (beta coefficient -78 (95%CI -106 - -50) ng/ml, p=0.000) and skin thickness was associated with higher serum levels of PCSK9 (beta coef. 22 (7-37) units, p=0.005). PCSK9 was significantly and positively associated with cIMT (beta coef. 0.65 (0.06-1.24) ng/ml, p=0.031) in SS patients after multivariable adjustment., Conclusions: PCSK9 serum concentration is downregulated in SS patients compared to controls and is directly associated with disease severity subrogated parameters. PCSK9 was independently related to cIMT in SS patients.

Objectives: The prevalence of fibromyalgia (FM) differs depending on the population studied. The main objective of the EPISER2016 study was to estimate the prevalence of FM in adults in Spain. The secondary objective was to evaluate the association with sociodemographic and anthropometric characteristics and smoking., Methods: This is a population-based cross-sectional multicentre study. The random selection was based on multistage stratified cluster sampling. The final sample comprised 4916 persons aged ≥20 years. Participants were contacted by telephone for completion of a screening survey. Investigating rheumatologists evaluated positive results (review of medical records and/or telephone interview, with medical visit if needed) to confirm the diagnosis. Prevalence and 95% confidence interval were calculated, taking into account the sample design. Weighing was applied based on age, sex, and geographic origin. Predictive models were constructed to analyse which sociodemographic, anthropometric and lifestyle variables in the call centre questionnaire were associated with the presence of FM., Results: 602 subjects (12.25%) had a positive screening result for FM, of which 24 were missing (3.99%). A total of 141 cases of FM were recorded. The estimated prevalence was 2.45% (95% CI, 2.06-2.90). Female sex was the variable most associated with FM, with an odds ratio (OR) of 10.156 (95% CI, 5.068-20.352). Peak prevalence was at 60-69 years (p=0.009, OR=6.962). FM was 68% more frequent in obese individuals (OR, 1.689; 95% CI, 1.036-2.755)., Conclusions: The prevalence of FM in adults in Spain barely changed between 2000 and 2016 and it is similar to that observed in Europe as a whole.

Primary Sjögren's syndrome (pSS) is an autoimmune exocrinopathy in which the role that the immune response plays in reducing exocrine gland function, including the glandular microenvironment of cytokines, has not been fully understood. Epithelial cells from biopsies of human parotid gland (HPG) were used to establish a model of human salivary gland in vitro. In this model, the functional consequences of several proinflammatory soluble factors present in the pSS glandular microenvironment were assessed. Stimulation with isoproterenol and calcium produced a significant increase in the basal activity of amylase in the HPG cell supernatants. Under these conditions, the presence of TNF-α and CXCL12 increased amylase mRNA cellular abundance, but reduced the amylase activity in the cell-free supernatant in a dose-dependent manner. IL-1β and IFN-γ, but not TGF-β, also diminished amylase secretion by HPG cells. These results suggest that the glandular microenvironment of cytokine, by acting post-transcriptionally, may be responsible, at least in part, for the reduced exocrine function observed in pSS patients. These data may help to a better understanding of the pathogenesis of SS, which in turn would facilitate the identification of new therapeutic targets for this disorder.

Objectives: We aimed to investigate whether the abnormalities in body composition and abdominal fat that occur in rheumatoid arthritis (RA) are associated with the presence of endothelial dysfunction., Methods: Cross-sectional study that encompassed 197 women (100 RA patients and 97 age-matched controls). Patients and controls were evaluated to establish endothelial function by brachial artery flow-mediated dilatation (FMD). Dual-x-ray-absorptiometry-derived body composition and abdominal adiposity by magnetic resonance imaging were assessed. Multiple regression analysis was performed to study the relationship between body composition and endothelial function., Results: FMD was higher in controls compared to RA patients (8.5 [4.5-15.6] % vs. 5.3 [0.0-9.2] %, p=0.00). Appendicular-to-total lean mass ratio (0.42 ± 0.02 vs. 0.40 ± 0.03, p=0.00) and appendicular-to-trunk lean mass (0.82 ± 0.08 vs. 0.78 ± 0.08, p=0.00) were lower in RA patients. Visceral and subcutaneous abdominal fat tissues did not differ between patients and controls. Body mass index over 30 kg/m2 was common in patients and controls (44 and 32%). High sarcopenia tended to be more elevated in RA after multivariate adjustment (13% vs. 7%, p=0.06). Fat mass index showed a negative association (per standard deviation-SD-), after adjusting for comorbidity, with FMD in controls (beta coef. -0.45[-1.05-0.05], p=0.03) but not in patients. Overfat definition (beta coef. -0.81[-1.73-0.00], p=0.05) and visceral fat (per SD beta coef. -0.60 [-1.18-0.02], p=0.04) were associated with a lower FMD values in controls but not in RA patients. Trend analysis revealed that sarcopenia was related to increased endothelial dysfunction in both patients and controls., Conclusions: Our findings suggest that fat accumulation is not associated with endothelial dysfunction in RA patients. However, RA patients with sarcopenia are more likely to suffer endothelial dysfunction possibly being at higher cardiovascular risk.

Objectives: We aimed to investigate whether the abnormalities in bone mineral density (BMD) that occur in patients with rheumatoid arthritis (RA) are associated with the presence of endothelial dysfunction., Methods: Cross-sectional study encompassing 216 subjects (111 patients with RA and 105 age- and sex-matched controls) without history of cardiovascular disease. Endothelial function was determined by brachial artery flow-mediated dilatation (FMD) and BMD by dual x-ray absorptiometry (DXA) measurements. Plasma vitamin D and osteoprotegerin serum (OPG) levels were assessed in patients and controls. Multiple regression analysis was performed to study the relationship between BMD with endothelial function, taking into account vitamin D and OPG levels., Results: After adjusting for traditional cardiovascular risk factors, vitamin D and OPG levels, BMD emerged as an independent factor associated with lower FMD values in controls, but not in patients with RA. Although OPG levels were inversely associated with FMD values in both RA patients and controls after adjusting for BMD, vitamin D showed this relationship only in the controls., Conclusions: Whilst OPG is associated with endothelial function in RA patients and controls, vitamin D levels and BMD are related to endothelial function in controls but not in patients with RA.

It has been recently described that some non-steroidal anti-inflammatory drugs (NSAIDs) are able to induce the shedding of L-selectin in neutrophils, an adhesion molecule that plays an essential role in the inflammatory response. We have found that, according to this capability, NSAIDs could be grouped into three categories. A high releaser group (flufenamic, meclofenamic, and mefenamic acids, diclofenac and aceclofenac), a group of moderate releasers (aspirin, indomethacin, nimesulide, flurbiprofen, and ketoprofen), and a non-releaser group (phenylbutazone and the oxicams, piroxicam and meloxicam). Only NSAIDs from the high releaser group shared diphenylamine in their chemical structure. The amine group of this chemical agent proved to be essential for the anti-L-selectin activity of diphenylamine-based NSAIDs. The presence of a carboxylic acid group in the diphenylamine (N-phenylanthranilic acid) highly increased its ability to reduce the L-selectin surface expression in neutrophils. Diphenylamine and N-phenylanthranilic acid neither affected COX activity in platelets nor modified the activation state of neutrophils. Diphenylamine-related compounds, which include the diphenylamine-based NSAIDs caused a variable reduction in the neutrophil intracellular ATP concentration, which correlated with the differential ability of such compounds to trigger L-selectin shedding (r = 0.97, p < 0.01). Diphenylamine-related compounds failed to down-regulate L-selectin in a tumor necrosis factor-alpha-converting enzyme (TACE)-deficient murine monocytic cell line. Our data indicate that diphenylamine seems to be the structural core of NSAIDs accounting for their down-regulatory activity of L-selectin leukocyte expression. Diphenylamine and its related compounds exert this action on L-selectin through a prostaglandin-independent, TACE-dependent mechanism that seems to be linked to the capability of these agents to uncouple the mitochondrial oxidative phosphorylation.