Unraveling the parahormetic mechanism underlying the health-protecting effects of grapeseed procyanidins

Proanthocyanidins (PACs), the predominant constituents within Grape Seed Extract (GSE), are intricate compounds composed of interconnected flavan-3-ol units. Renowned for their health-affirming properties, PACs offer a shield against a spectrum of inflammation associated diseases, such as diabetes, obesity, degenerations and possibly cancer. While monomeric and dimeric PACs undergo some absorption within the gastrointestinal tract, their larger oligomeric and polymeric counterparts are not bioavailable. However, higher molecular weight PACs engage with the colonic microbiota, fostering the production of bioavailable metabolites that undergo metabolic processes, culminating in the emergence of bioactive agents capable of modulating physiological processes. Within this investigation, a GSE enriched with polymeric PACs was employed to explore in detail their impact. Through comprehensive analysis, the present study unequivocally verified the gastrointestinal-mediated transformation of medium to high molecular weight polymeric PACs, thereby establishing the bioaccessibility of a principal catabolite termed 5-(3',4'-dihydroxyphenyl)-γ-valerolactone (VL). Notably, our findings, encompassing cell biology, chemistry and proteomics, converge to the proposal of the notion of the capacity of VL to activate, upon oxidation to the corresponding quinone, the nuclear factor E2-related factor 2 (Nrf2) pathway-an intricate process that incites cellular defenses and mitigates stress-induced responses, such as a challenge brought by TNFα. This mechanistic paradigm seamlessly aligns with the concept of para-hormesis, ultimately orchestrating the resilience to stress and the preservation of cellular redox equilibrium and homeostasis as benchmarks of health.

Cardiolipin drives the catalytic activity of GPX4 on membranes: Insights from the R152H mutant

The aim of this study was to examine, in biochemical detail, the functional role of the Arg152 residue in the selenoprotein Glutathione Peroxidase 4 (GPX4), whose mutation to His is involved in Sedaghatian-type Spondylometaphyseal Dysplasia (SSMD). Wild-type and mutated recombinant enzymes with selenopcysteine (Sec) at the active site, were purified and structurally characterized to investigate the impact of the R152H mutation on enzymatic function. The mutation did not affect the peroxidase reaction's catalytic mechanism, and the kinetic parameters were qualitatively similar between the wild-type enzyme and the mutant when mixed micelles and monolamellar liposomes containing phosphatidylcholine and its hydroperoxide derivatives were used as substrate. However, in monolamellar liposomes also containing cardiolipin, which binds to a cationic area near the active site of GPX4, including residue R152, the wild-type enzyme showed a non-canonical dependency of the reaction rate on the concentration of both enzyme and membrane cardiolipin. To explain this oddity, a minimal model was developed encompassing the kinetics of both the enzyme interaction with the membrane and the catalytic peroxidase reaction. Computational fitting of experimental activity recordings showed that the wild-type enzyme was surface-sensing and prone to "positive feedback" in the presence of cardiolipin, indicating a positive cooperativity. This feature was minimal, if any, in the mutant. These findings suggest that GPX4 physiology in cardiolipin containing mitochondria is unique, and emerges as a likely target of the pathological dysfunction in SSMD.

A white paper on Phospholipid Hydroperoxide Glutathione Peroxidase (GPx4) forty years later

The purification of a protein inhibiting lipid peroxidation led to the discovery of the selenoperoxidase GPx4 forty years ago. Thus, the evidence of the enzymatic activity was reached after identifying the biological effect and unambiguously defined the relationship between the biological function and the enzymatic activity. In the syllogism where GPx4 inhibits lipid peroxidation and its inhibition is lethal, cell death is operated by lipid peroxidation. Based on this rationale, this form of cell death emerged as regulated iron-enforced oxygen toxicity and was named ferroptosis in 2012. In the last decades, we learned that reduction of lipid hydroperoxides is indispensable and, in cooperation with prooxidant systems, controls the critical steady state of lipid peroxidation. This concept defined the GPx4 reaction as both the target for possible anti-cancer therapy and if insufficient, as cause of degenerative diseases. We know the reaction mechanism, but the details of the interaction at the membrane cytosol interface are still poorly defined. We know the gene structure, but the knowledge about expression control is still limited. The same holds true for post-transcriptional modifications. Reverse genetics indicate that GPx4 has a role in inflammation, immunity, and differentiation, but the observations emerging from these studies need a more specifically addressed biochemical evidence. Finally, the role of GPx4 in spermatogenesis disclosed an area unconnected to lipid peroxidation. In its mitochondrial and nuclear form, the peroxidase catalyzes the oxidation of protein thiols in two specific aspects of sperm maturation: stabilization of the mid-piece and chromatin compaction. Thus, although available evidence converges to the notion that GPx4 activity is vital due to the inhibition of lipid peroxidation, it is reasonable to foresee other unknown aspects of the GPx4 reaction to be disclosed.

AB1182 SPECIALIZED PRO-RESOLVING MEDIATORS (SPMS) AND INFLAMMATORY NETWORKS IN PATIENTS AFFECTED BY ADULT ONSET STILL’S DISEASE (AOSD) AND COVID-19

Background

Uncontrolled systemic inflammation characterizes COVID-19 and autoinflammatory diseases such as adult-onset Still’s disease (AOSD). Biosynthesis of pro-resolving mediators (SPMs), i.e. lipoxins (LX), resolvins (Rv), protectins (PD), and maresins (MaR), ensures inflammation shutdown and tissue repair, limiting neutrophils recruitment and stimulating macrophages to remove apoptotic cells. Among protectins, reduction of PD1 was found in the lungs of mice infected with the H5N1 influenza virus and experimental treatment with PD1 resulted in increased animals’ survival (Morita M et al 2013).

Objectives

We investigated the effects of SPMs in pathogenesis and clinical evolution of AOSD and compared these data with mild and severe COVID-19. Finally, we analyzed the potential role of PD1 in modulating the inflammatory response of macrophages obtained from AOSD patients, COVID-19 patients and healthy donors (HDs).

Methods

21 patients hospitalized for COVID-19 (10 ICU and 11 hospitalized in medical clinical unit) and 13 patients with AOSD were enrolled. Plasma PD1 levels from patients and controls were analyzed by ELISA, and monocytes-derived macrophages were polarized into M1 and M2 phenotype. We analyzed the effect of PD-1 on macrophages differentiation. At 10 days, macrophages were analyzed for surface expression of subtypes markers by flow cytometry. Cytokines production was measured in supernatants by Bio-Plex Assays. Peripheral blood mononuclear cells (PBMCS) from 3 AOSD patients, 2 COVID-19 patients and 3 HDs were obtained. Next-generation deep sequencing was then performed to identify the differences in PBMCs transcripts profiles.

Results

AOSD patients with systemic scored (SS) ≥1 showed an increase of PD1 levels compared to AOSD patients with lower systemic score (p=0.04) (Figure 1A). Similarly, plasma levels of PD1 were increased in COVID-19 patients independently from their clinical subsets, compared to HDs (p=0.02). In vitro treatment with PD1 of monocytes-derived macrophages from AOSD and COVID-19 patients induced a significant increase of M2 polarization vs control (p<0.05) (Figure 1B). Furthermore, a significant release of IL-10 and CCL4 from M2 macrophages was observed when compared to control (p<0.05) (Figure 1C). In the transcriptomes from 3 AOSD patients (2 mild and 1 severe), 2 COVID-19 patients (1 mild and 1 ICU) and 2 HDs, we observed that genes involved in inflammation, lipid catabolism and monocytes activation were specifically dysregulated in AOSD and COVID-19 patients when compared to HDs. Among them pla2g15, pla2g12a, pla2g2d, involved in mobilization of SPMs precursors, were significant upregulated in patients compared to HDs (p<.01, |log2FoldChange|>1.2) (Figure 1D). The largest part of the genes involved in inflammation, lipid catabolism, and monocytes activation are less expressed in AOSD patients when compared to COVID19 patients, as reported in Table 1.

Table 1.Gene symbolLog2 fold changepAdjusted pCounts COVID19Counts AOSDInflammation-related genesALOX50.980.0240.2116861.618562.92IL13RA11.280.0020.0537154.782938.95RTN30.720.0020.00699948.376045.92SSH21.056,78 E-70.0001618343.868848.67Lipid catabolism genesPLBD11.680.000110.008228051.888671.3CYP4F32.850.000340.0171996.63277.13STS1.530.0100.0361798.5623.9HADHA0.740.000140.009712766.447625.38Monocytes-related genesALDH21.462.48E-101.85E-079186.553340.87CD1632.379,99E-060.001466499.4512870.59MGST11.130.00260.0631385.54631.67RNASE42.480.00010.009286.6615.42Figure 1.

Conclusion

The counterbalance by SPMs during inflammation is still a largely unexplored pathway. Our study suggests that an imbalance of SPMs in autoinflammatory diseases as well as COVID-19. The modulation of SPMs as observed in our experiments, might represent a new possible therapeutic strategy during AOSD and COVID-19.

References

[1]Morita M et al. The lipid mediator protectin D1 inhibits influenza virus replication and improves severe influenza. Cell. 2013;153:112-25.

Disclosure of Interests

luca navarini Speakers bureau: AbbVie, Pfizer, MSD, UCB, GSK, BMS, Roche, Sanofi Aventis, Novartis, Janssen, Galapagos, Eli Lilly, Paid instructor for: AbbVie, Eli Lilly, Consultant of: Philogen, Grant/research support from: AbbVie, Marta Vomero: None declared, Onorina Berardiucrti: None declared, Damiano Currado: None declared, Annalisa Marino: None declared, Alice Biaggi: None declared, Stefano Di Donato: None declared, Francesco Ursini: None declared, Piero Ruscitti: None declared, Riccardo Meliconi: None declared, Paola Cipriani: None declared, Annamaria Iagnocco Speakers bureau: AbbVie, Pfizer, MSD, UCB, GSK, BMS, Roche, Sanofi Aventis, Novartis, Janssen, Galapagos, Eli Lilly, Antonella Afeltra Speakers bureau: AbbVie, Pfizer, MSD, UCB, GSK, BMS, Roche, Sanofi Aventis, Novartis, Janssen, Galapagos, Eli Lilly, Roberto Giacomelli Speakers bureau: AbbVie, Pfizer, MSD, UCB, GSK, BMS, Roche, Sanofi Aventis, Novartis, Janssen, Galapagos, Eli Lilly, SOBI, Consultant of: Philogen, Grant/research support from: AbbVie, SOBI

AB0725 Scleroderma study group Emilia Romagna (Sclero-RER): real life use of prostacyclin analog. Preliminary data from a multicentric survey

Background

Systemic Sclerosis (SSc) is a complex autoimmune disease characterized by vascular damage, immune activation and fibrosis of skin and internal organs 1. Raynaud phenomenon (RP) is frequently the first symptom of the disease and growing evidences are supporting the hypothesis the SSc may be a vascular disease, with a pivotal role of endothelial cells, particularly in the very early phase2,3. Robust data support the use of vascular active drug to treat RP and to prevent vascular complication4–7.

Objectives

The use of prostacyclin analog (PA) is evertything but standardized, with different regimen used all around the Country. We report data on the use of PA in a multicentric regional reality to understand which regimen are prevalent (and why) and if there is the opportunity to standardized them.

Methods

We collected data from an online survey exploring different items related to the use of PA.

Results

Survey was fullfilled by 12 sites: 5 university hospital and 7 local hospitals, 7 driven by Rheumatologist and 5 from internal medicine specialists with/without concomitant rheumatologists. PA are ubiquitarly used for SSc-related digital ulcers (SSc-DU) and secondary RP but only a half of sites use it for primary RP. Seventy-five percent of sites (9/12) dispense PA at least once a month, but some other (1 each one respectively) on weekly basis, every other month or every 7 weeks. Drug administration may last from 2 to 5 consecutive days (mean 1.91+/- 1.5SD) with drug dose ranging from 0.5 to 2 ng/Kg/min with a minimum variability from site to site. Our regional hospitals may count on overall 68 spots, some available as beds (outpatient or inpatient), some as reclining chair or chair (outpatients only). University centers have usually more assigned personnel than local hospital (on average: 2 versus 1.5 physicians, 2 versus 1.2 nurse). Sites are able to offer meals (except one) and are able to accomodate from 1 to 12 patients at the same time (mean 3.45, +/- 3.2SD).

Conclusion

PA has known benefit in vascular involvement in SSc patients. Despite a multicenter palcebo-control study8 defining time and dose of this drugs and subsequent data based on the same regimen9, there is no homogeneity in treatment administration. The unequal treatment, based on our data, seems due to limited resources and personnel. High variability has been found in regimen duration and administration frequency.

References

[1]Ferri, C. et al. Systemic sclerosis evolution of disease pathomorphosis and survival. Our experience on Italian patients’ population and review of the literature. Autoimmunity Reviews vol. 13 1026–1034 (2014).

[2]Mulligan-Kehoe, M. J. et al. Antiangiogenic plasma activity in patients with systemic sclerosis. Arthritis Rheum.56, 3448–58 (2007).

[3]Wigley, F. M. Vascular disease in scleroderma. Clin. Rev. Allergy Immunol.36, 150–75 (2009).

[4]Brueckner, C. S. et al. Effect of sildenafil on digital ulcers in systemic sclerosis: Analysis from a single centre pilot study. Ann. Rheum. Dis.69, 1475–1478 (2010).

[5]Kowal-Bielecka, O. et al. EULAR recommendations for the treatment of systemic sclerosis: A report from the EULAR Scleroderma Trials and Research group (EUSTAR). Ann. Rheum. Dis.68, 620–628 (2009).

[6]Matucci-Cerinic, M. et al. Bosentan treatment of digital ulcers related to systemic sclerosis: Results from the RAPIDS-2 randomised, double-blind, placebo-controlled trial. Ann. Rheum. Dis.70, 32–38 (2011).

[7]Herrick, A. L. & Wigley, F. M. Raynaud’s phenomenon. Best Practice and Research: Clinical Rheumatology (2020) doi:10.1016/j.berh.2019.101474.

[8]Wigley, F. M. et al. Intravenous iloprost infusion in patients with Raynaud phenomenon secondary to systemic sclerosis: A multicenter, placebo-controlled, double- blind study. Ann. Intern. Med.120, 199–206 (1994).

[9]Cappelli, L. & Wigley, F. M. Management of Raynaud Phenomenon and Digital Ulcers in Scleroderma. Rheumatic Disease Clinics of North America vol. 41 419–438 (2015).

Disclosure of Interests

None declared

POS1267 LONG-TERM SURVEY STUDY OF THE IMPACT OF COVID-19 ON SYSTEMIC AUTOIMMUNE DISEASES. LOW DEATH RATE DESPITE THE INCREASED PREVALENCE OF SYMPTOMATIC INFECTION. ROLE OF PRE-EXISTING INTERSTITIAL LUNG DISEASE AND ONGOING TREATMENTS

Background

Patients with autoimmune systemic diseases (ASDs) can be counted among frail populations as regards the predisposition to COVID-19 due to the frequent visceral organ involvement and comorbidities, as well as the ongoing immunomodulating treatments.

Objectives

Our long-term multicenter telephone survey prospectively investigated the prevalence, prognostic factors, and outcomes of COVID-19 in Italian ASD patients during the first 3 pandemic waves.

Methods

A large series of 3,918 ASD patients (815 M, 3103 F; mean age 59±12SD years) was consecutively recruited at the 36 referral centers of COVID-19 & ASD Italian Study Group. In particular, ASD series encompassed the following conditions: rheumatoid arthritis (n: 981), psoriatic arthritis (n: 471), ankylosing spondylitis (n: 159), systemic sclerosis (n: 1,738), systemic lupus (172), systemic vasculitis (n: 219), and a miscellany of other ASDs (n: 178). The development of COVID-19 was recorded by means of telephone survey using standardized symptom-assessment questionnaire (1).

Results

A significantly increased prevalence of COVID-19 (8.37% vs 6.49%; p<0.0001) was observed in our ASD patients, while the cumulative death rate revealed statistically comparable to the Italian general population (3.65% vs 2.95%; p: ns). In particular, among the 328 ASD patients complicated by COVID-19, 57 (17%) needed hospitalization, while mild-moderate manifestations were observed in the large majority of individuals (83%). In addition, 12/57 hospitalized patients died due to severe interstitial pneumonia and/or cardiovascular manifestations.

Interestingly, a significantly higher COVID-19-related death rate was observed in systemic sclerosis patients compared to the Italian general population (6.29% vs 2.95%; p=0.018). Other adverse prognostic factors to develop COVID-19 were the patients’ older age, male gender, pre-existing ASD-related interstitial lung involvement, and chronic steroid treatment. Conversely, patients treated with conventional synthetic disease-modifying antirheumatic drugs (csDMARDs) showed a significantly lower prevalence of COVID-19 compared to those without (3.58% vs 46.99%; p=0.000), as well as the chronic administration of low dose aspirin in a subgroup of SSc patients (with 5.57% vs without 27.84%; p=0.000).

Conclusion

The cumulative impact of COVID-19 on ASD patients after the first 3 pandemic waves revealed less severe than that observed during the first phase of pandemic (1), especially with regards to the death rate that was comparable to the Italian general population in spite of the increased prevalence of complicating COVID-19 in the same ASD series.

Ongoing long-term treatments, mainly csDMARDs, might usefully contribute to generally positive outcomes of in this frail patients’ population.

Of note, a significantly increased COVID-19-related mortality was recorded in only SSc patients’ subgroup, possibly favored by pre-existing lung fibrosis. Among different ASD, SSc deserves special attention, since it shares the main pathological alterations with COVID-19, namely the interstitial lung involvement and the endothelial injury responsible for diffuse microangiopathy.

Besides SSc, the patients’ subgroups characterized by older age, chronic steroid treatment, pre-existing interstitial lung disease, and/or impaired COVID-19 vaccine response (1-3), may deserve well-designed prevention and management strategies.

References

[1]Ferri C, et al. Ann Rheum Dis. 2020 Oct 14 doi: 10.1136/annrheumdis-2020-219113.

[2]Ferri C et al. J Autoimmun. 2021 Dec;125:102744. doi: 10.1016/j.jaut.2021.102744.

[3]Visentini M et al. Ann Rheum Dis. 2021 Nov 24. doi: 10.1136/annrheumdis-2021-221248

Disclosure of Interests

None declared

AB0261 CARDIOMETABOLIC COMORBIDITIES MAY IDENTIFY A MORE SEVERE SUBSET OF RHEUMATOID ARTHRITIS, RESULTS FROM A “REAL-LIFE” STUDY

Background

Rheumatoid arthritis (RA) is a chronic systemic inflammatory disease associated with a significant increased rate of cardiometabolic comorbidities contributing to an increased risk of morbidity and mortality of these patients [1,2]. RA patients with cardiometabolic comorbidities might differ from those without in their clinical presentation and prognosis.

Objectives

This “real-life” cross-sectional study was designed to describe disease features of RA consecutive participants affected by cardiometabolic comorbidities than those without, among those attending recruiting centres from January 1, 2021 to December 31, 2021. Our purpose was also the identification of possible associations between these diseases and clinical characteristics of patients (i.e. fulfilment of ACR1987 criteria, ACPA positivity, presence of extra-articular manifestations, remission, and bDMARD failure).

Methods

Consecutive RA patients were assessed, all fulfilling 2010 ACR/EULAR criteria for RA. We have defined the participant as having such comorbidities if affected by 2 or 3 among high blood pressure (HBP), type 2 diabetes (T2D), and/or dyslipidaemia. The presence of cardiometabolic comorbidities for each participant was verified by reviewing the clinical charts, interview, and extensive medical examinations. Patients with and without cardiometabolic comorbidities were grouped and compared. After that, regression models were built to assess the influence of the presence of cardiometabolic comorbidities on RA features of disease severity.

Results

757 consecutive RA participants were evaluated [(female 56.6%, age 64.7 ± 12.3 years, median disease duration 6 years (IQR 12)]. Among assessed participants, 13.5% showed cardiometabolic comorbidities. These were older (63.9 ± 13.1 vs 70.4 ± 9.0 years, p<0.001) and characterised by a longer disease duration with 64.7% between 5 and 10 years (p=0.003). They were more often affected by extra-articular manifestations (8.2% vs 17.7%, p=0.029) and frequently displayed smoking habit (36.6% vs 50.0%, p=0.003). A lower percentage of participants with these comorbidities was in remission (15.7% vs 8.5%, p=0.048) and they showed a higher prevalence of history of bDMARD failure (40.4% vs 78.4%, p<0.001).

Finally, regression models showed that cardiometabolic comorbidities were significantly correlated with RA features of disease severity. Participants with cardiometabolic comorbidities more frequently fulfilled ACR1987 criteria in both univariate (OR: 1.47, 95%CI: 1.15-1.89, p=0.002) and multivariate analyses (OR: 1.48, 95%CI: 1.15-1.91, p=0.002). These participants had a higher probability of ACPA positivity in both univariate (OR: 1.52, 95%CI: 1.10-2.09, p=0.009) and multivariate analyses (OR: 1.47, 95%CI: 1.06-2.04, p=0.020). Cardiometabolic comorbidities also predicted the presence of extra-articular manifestations in both univariate (OR: 3.26, 95%CI: 1.77-5.89, p<0.001) and multivariate analyses (OR: 2.41, 95%CI: 1.30-4.87, p=0.005). Participants with cardiometabolic comorbidities had a higher probability of previous bDMARD failure in both univariate (OR: 1.73, 95%CI: 1.24-2.43, p<0.001) and multivariate analyses (OR: 7.17, 95%CI: 3.61-14.2, p<0.001). Cardiometabolic comorbidities resulted to be a negative predictor of being in remission in both univariate (OR: 0.53, 95%CI: 0.39-0.97, p=0.041) and multivariate analyses (OR: 0.61, 95%CI: 0.41-0.96, p=0.035).

Conclusion

We described disease features of RA participants with cardiometabolic comorbidities, identifying a disease subset characterised by clinical features of disease severity and to be considered as “difficult-to-treat”. Thus, cardiometabolic comorbidities may represent a considerable burden for RA patients requiring an appropriate management which should focus, in addition to cardiovascular risk prediction, on targeting these metabolic components.

References

[1]England BR, et al. BMJ. 2018;361:k1036.

[2]Ferguson LD, et al. Nat Rev Rheumatol. 2019;15:461-474.

Disclosure of Interests

None declared

OP0044 CYTOKINE PROFILE, HYPERFERRITINEMIA, AND MULTI-VISCERAL INVOLVEMENT CHARACTERISE MACROPHAGE ACTIVATION SYNDROME COMPLICATING ADULT ONSET STILL’S DISEASE. RESULTS FROM A MULTIDIMENSIONAL EVALUATION

Background

Adult-onset Still’s disease (AOSD) is a rare multigenic autoinflammatory disease of unknown aetiology burdened by life-threatening, such as macrophage activation syndrome (MAS) [1]. Considering the poor outcome of MAS patients, previous works tried to assess predictive factors of its occurrence during AOSD [2-4]. However, an integrated evaluation of clinical features with biomolecules, more reflecting the pathogenic mechanisms of the disease and its complications, is still missing.

Objectives

To multidimensionally characterise MAS complicating AOSD considering cytokine profile, inflammatory markers, and multi-visceral involvement of the disease. To perform a high-dimensional phenotypic analysis of circulating immune cells in AOSD patients with and without MAS. To assess interferon (IFN)-related pathways in AOSD synovial tissues by a bulky RNA sequencing.

Methods

The present evaluation was designed to multidimensionally compare AOSD patients with or without MAS, considering cytokine profile, inflammatory markers, and multi-visceral involvement of the disease. Clinical and biologic data were collected and compared in AOSD patients with and without MAS. Sera biomolecules were analysed by Luminex multiplexing technology. Mass cytometry (CyTOF) was used to characterise circulating immune cells. A bulky RNA sequencing was performed in AOSD synovial tissues.

Results

In this study, 40 consecutive AOSD patients (47.7±15.0 years, 50.0% male gender) were assessed at the time of diagnosis before the administration of any immunosuppressive therapy. Out of those, 14 (35%) patients were complicated by MAS. Paralleling with increases of systemic score and ferritin, MAS patients were characterised by an increased concentration of IL-1α, IL-1β, IL-1Ra, IL-2Ra, IL-6, IL-10, IL-17A, IFN-γ, G-CSF, MCP-1, MIP-1α, SCF. Among these biomolecules, IL-1Ra, IFN-γ, MCP-1, and SCF were correlated with MAS.

Combining the discriminatory ability of these data in identifying MAS, the best model was composed by systemic score, ferritin, IFN-γ, and IL-10. This model was characterised by AUC=0.99 (Standard error: 0.008; 95%CI: 0.976–1.000), sensitivity=100%, specificity=95.45%. By CyTOF analysis, AOSD patients, who were complicated or not with MAS were characterised by a significant increase of circulating “classical monocytes” (CD14+CD38+). MAS patients were characterised by a significant reduction of NK cells (CD45RA+CD56dim) than AOSD patients. Finally, the transcriptomic profile, by RNA-sequencing analysis, showed that 3477 among type I, II, and III IFN-related genes (IRGs) were significantly different in AOSD synovial tissues.

Conclusion

A multidimensional characterisation of AOSD patients was provided suggesting that IFN-γ, IL-10, ferritin, and systemic score discriminated MAS, thus identifying the occurrence of the cytokine storm syndrome. The inflammatory milieu of AOSD and MAS may be associated with a signature of circulating immune cells. Finally, our results about IRGs reinforced the role of IFN-γ in these patients.

References

[1]Giacomelli R, Ruscitti P, Shoenfeld Y. A comprehensive review on adult onset Still’s disease. J Autoimmun. 2018;93:24-36.

[2]Ruscitti P, et al. Macrophage Activation Syndrome in Patients Affected by Adult-onset Still Disease: Analysis of Survival Rates and Predictive Factors in the Gruppo Italiano di Ricerca in Reumatologia Clinica e Sperimentale Cohort. J Rheumatol. 2018;45:864-872.

[3]Di Benedetto P, et al. Ferritin and C-reactive protein are predictive biomarkers of mortality and macrophage activation syndrome in adult onset Still’s disease. Analysis of the multicentre Gruppo Italiano di Ricerca in Reumatologia Clinica e Sperimentale (GIRRCS) cohort. PLoS One. 2020;15:e0235326.

[4]Wan L, et al. Total metabolic lesion volume of lymph nodes measured by 18F-FDG PET/CT: a new predictor of macrophage activation syndrome in adult-onset Still’s disease. Arthritis Res Ther. 2021;23:97.

Disclosure of Interests

None declared.

Hydrogen peroxide signaling via its transformation to a stereospecific alkyl hydroperoxide that escapes reductive inactivation

During systemic inflammation, indoleamine 2,3-dioxygenase 1 (IDO1) becomes expressed in endothelial cells where it uses hydrogen peroxide (H₂O₂) to oxidize L-tryptophan to the tricyclic hydroperoxide, cis-WOOH, that then relaxes arteries via oxidation of protein kinase G 1α. Here we show that arterial glutathione peroxidases and peroxiredoxins that rapidly eliminate H₂O₂, have little impact on relaxation of IDO1-expressing arteries, and that purified IDO1 forms cis-WOOH in the presence of peroxiredoxin 2. cis-WOOH oxidizes protein thiols in a selective and stereospecific manner. Compared with its epimer trans-WOOH and H₂O₂, cis-WOOH reacts slower with the major arterial forms of glutathione peroxidases and peroxiredoxins while it reacts more readily with its target, protein kinase G 1α. Our results indicate a paradigm of redox signaling by H₂O₂ via its enzymatic conversion to an amino acid-derived hydroperoxide that 'escapes' effective reductive inactivation to engage in selective oxidative activation of key target proteins.

Production and purification of homogenous recombinant human selenoproteins reveals a unique codon skipping event in E. coli and GPX4-specific affinity to bromosulfophthalein

Selenoproteins are translated via animal domain-specific elongation machineries that redefine dedicated UGA opal codons from termination of translation to selenocysteine (Sec) insertion, utilizing specific tRNA species and Sec-specific elongation factors. This has made recombinant production of mammalian selenoproteins in E. coli technically challenging but recently we developed a methodology that enables such production, using recoding of UAG for Sec in an RF1-deficient host strain. Here we used that approach for production of the human glutathione peroxidases 1, 2 and 4 (GPX1, GPX2 and GPX4), with all these three enzymes being important antioxidant selenoproteins. Among these, GPX4 is the sole embryonically essential enzyme, and is also known to be essential for spermatogenesis as well as protection from cell death through ferroptosis. Enzyme kinetics, ICP-MS and mass spectrometry analyses of the purified recombinant proteins were used to characterize selenoprotein characteristics and their Sec contents. This revealed a unique phenomenon of one-codon skipping, resulting in a lack of a single amino acid at the position corresponding to the selenocysteine (Sec) residue, in about 30% of the recombinant GPX isoenzyme products. We furthermore confirmed the previously described UAG suppression with Lys or Gln as well as a minor suppression with Tyr, together resulting in about 20% Sec contents in the full-length proteins. No additional frameshifts or translational errors were detected. We subsequently found that Sec-containing GPX4 could be further purified over a bromosulfophthalein-column, yielding purified recombinant GPX4 with close to complete Sec contents. This production method for homogenously purified GPX4 should help to further advance the studies of this important selenoprotein.

Homeostatic control of redox status and health

Research on oxidants and electrophiles has shifted from focusing on damage to biomolecules to the more fine-grained physiological arena. Redox transitions as excursions from a steady-state redox set point are continually ongoing in maintenance of redox balance. Current excitement on these topics results from the fact that recent research provided mechanistic insight, which gives rise to more concrete and differentiated questions. This Commentary focuses on redox eustress and the feedback restoration of steady state as concepts in active maintenance of physiological health, with brief discussion of redox stress response to viral infection, exemplified by COVID-19.

POS1246 COVID-19 IN ITALIAN PATIENTS WITH RHEUMATIC AUTOIMMUNE SYSTEMIC DISEASES: RESULTS OF A NATIONWIDE SURVEY STUDY

Background:

SARS-CoV-2 infection poses a serious challenge for patients with rheumatic autoimmune systemic diseases (ASD), characterized by marked immune-system dysregulation and frequent visceral organ involvement.

Objectives:

To evaluate the impact of Covid-19 pandemic in a large series of Italian patients with ASD.

Methods:

Our multicenter telephone survey (8-week period, March-April 2020) included a large series of 2,994 patients (584 M, 2,410 F, mean age 58.9±13.4SD years) with ASD followed at 34 tertiary referral centers of 14 regions of northern, central, and southern Italian macro areas, characterized by different prevalence of SARS-CoV-2 infection. According to currently used criteria, Covid-19 was classified as definite Covid-19 (signs or symptoms of Covid-19 confirmed by positive oral/nasopharyngeal swabs at PCR testing) or highly suspected Covid-19 (signs or symptoms highly suggestive of Covid-19, but not confirmed by PCR testing due to limited availability of virological tests in that period). The results were analyzed performing the Odds Ratio by Java-Stat 2-way Contingency Table Analysis.

Results:

The main findings of the survey study revealed a significantly increased prevalence of Covid-19 in:

a.the whole series of ASD patients (definite Covid-19: 22/2994, 0.73%; p=0.0007;

definite Covid-19 plus highly suspected Covid-19: 74/2,994, 2.47%; p<0.0001) when compared to Italian general population of Covid-19 infected individuals (349/100000 = 0.34%; data from Italian Superior Institute of Health;

https://www.epicentro.iss.it/en/coronavirus/sars-cov-2-national-surveillance-system).

b.the subgroup of patients with connective tissue diseases or systemic vasculitis (n = 1,901) compared to the subgroup of inflammatory arthritis (n = 1,093), namely rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis (definite Covid-19: 19/1,901, 0.99%, vs 3/1,093, 0.27%; p=0.036; definite Covid-19 plus highly suspected Covid-19: 69/1,901, 3.6%, vs 5/1,093, 0.45%; p<0.0001)

c.the subgroup of patients with pre-existing interstitial lung involvement (n = 526) compared to those without (n = 2,468) (definite Covid-19: 10/526, 1.90%, vs 12/2,468, 0.48%; p=0.0015; definite Covid-19 plus highly suspected Covid-19: 33/526, 6.27%, vs 41/2,468, 1.66%; p<0.0001).

Of interest, the prevalence of Covid-19 did not correlate with presence/absence of different comorbidities, mainly diabetes, cardio-vascular and/or renal disorders, as well as of ongoing treatments with biological DMARDs; while patients treated with conventional DMARDs showed a significantly lower prevalence of Covid-19 compared to those without. Covid-19 was more frequently observed in the patients’ populations from northern and central compared to southern Italian macro area with lower diffusion of pandemic. Clinical manifestations of Covid-19, observed in 74 patients, were generally mild or moderate; 4/9 individuals requiring hospital admission died for severe pneumonia.

Conclusion:

The prevalence of Covid-19 observed in ASD patients during the first wave of pandemic was significantly higher than that observed in Italian general population; moreover, the actual prevalence of Covid-19 might be underestimated due to the high number of mild variants as well as the possible clinical overlapping between these two conditions. Patients with ASD should be invariably regarded as ‘frail patients’ during the pandemic course, considering the risk of worse outcome in the acute phase of Covid-19, as well as the potential long-term effects of viral infection.

The statistically significant association of Covid-19 with connective tissue diseases/systemic vasculitis, as well as with pre-existing interstitial lung involvement, suggests the presence of distinct clinico-pathological ASD subsets, characterized by markedly different patients’ vulnerability to SARS-CoV-2 infection.

Disclosure of Interests:

None declared

POS1349 THE JOINT INVOLVEMENT IN ADULT ONSET STILL’S DISEASE IS CHARACTERISED BY A PECULIAR MAGNETIC RESONANCE IMAGING AND A SPECIFIC TRANSCRIPTOMIC PROFILE

Background:

Adult onset Still’s disease (AOSD) is a rare systemic autoinflammatory disease and joint involvement is one of its clinical manifestations [1]. Arthritis, either oligoarthritis or bilateral symmetrical rheumatoid arthritis-like polyarthritis, is another common clinical feature of AOSD, with a migrating pattern at the beginning and becoming stable over the time [1].

Objectives:

The aims of the study were to assess joint involvement in AOSD by using magnetic resonance imaging (MRI), to describe main patterns of involvement, and associated clinical characteristics, and to evaluate the global transcriptomic profile of synovial tissues in AOSD to elucidate possible pathogenic pathways involved with.

Methods:

AOSD patients, who underwent to magnetic resonance imaging (MRI) exam on joints, were assessed to describe patterns of joint involvement and associated clinical characteristics. Some synovial tissues were collected for RNA-sequencing purposes.

Results:

In this study, 31 patients with AOSD (mean age 42.3 ± 15.2 years, 54.8% male gender), who underwent to at least one MRI exam on joints, were assessed. The most common MRI finding was the presence of synovitis on 60.5%, mainly in peripheral affected joints. MRI revealed a mild to moderate proliferative synovitis, as thickening of the synovial membrane, with low to intermediate signal intensity on T1-weighted images and intermediate to high signal intensity on T2-fat saturated weighted and STIR images, suggesting the presence of a hyperplastic than of a hypertrophied synovial tissue. Bone oedema and bone erosions were reported on 34.9% and 25.6% MRI exams, respectively. In all patients but one, bone erosions were synchronous with bone oedema, overlapping completely the locations. Assessing clinical characteristics in patients with MRI-erosions, a higher prevalence of splenomegaly, a more frequent chronic disease course, lower levels of erythrocyte sedimentation rate and ferritin was observed.

Assessing the synovial tissues of some AOSD patients, a moderate perivascular mononuclear infiltrate in the sub-lining stroma of hip synovial tissues was observed, whereas the lining cells were relatively unremarkable. In addition, interleukin (IL)-1β, IL-6, TNF, and heavy ferritin subunit (FeH) were found on AOSD synovial tissues.

An RNA-sequencing analysis assessed the global transcriptomic profile of synovial tissues on AOSD patients and matched-controls. Assessing IL-1 pathway, we found an increased expression of il1a, il1b, il1rap, il1r1, il18r1, and Il18bp on AOSD tissues when compared with controls. In IL-6 pathway, we found an increased expression of il6 and il6st/gp130 on AOSD synovial tissues whereas an increased expression of il6r was shown on the controls. Among genes involved in TNF pathway, tnf, traf1, traf2, tnfaip3 and tnfrsf1a resulted to be more expressed in AOSD synovial tissues than in controls. Finally, fth1 and ftl were more expressed in AOSD patients than controls, when we explored the iron uptake and transport pathway.

Conclusion:

A peculiar MRI pattern of joint involvement in AOSD was reported; the most common finding was the presence of synovitis, characterised by intermediate to high signal intensity on T2-fat-saturated weighted and STIR images. Bone erosions and bone oedema were also observed. This MRI pattern was associated with a hyper-activation of IL-1, IL-6, and TNF pathways together with a hyper-expression of ferritin genes on AOSD synovial tissues.

References:

[1]Giacomelli R, Ruscitti P, Shoenfeld Y. A comprehensive review on adult onset Still’s disease. J Autoimmun. 2018;93:24-36.

Disclosure of Interests:

None declared

Aerobic pyruvate metabolism sensitizes cells to ferroptosis primed by GSH depletion

Ferroptosis is a non-accidental, regulated form of cell death operated by lipid peroxidation under strict control of GPx4 activity. This is consistent with the notion that lipid peroxidation is initiated by radicals produced from decomposition of traces of pre-existing lipid hydroperoxides. The question, therefore, emerges about the formation of these traces of lipid hydroperoxides interacting with Fe²⁺. In the most realistic option, they are produced by oxygen activated species generated during aerobic metabolism. Screening for metabolic sources of superoxide supporting ferroptosis induced by GSH depletion, we failed to detect, in our cell model, a role of respiratory chain. We observed instead that the pyruvate dehydrogenase complex -as other α keto acid dehydrogenases already known as a major source of superoxide in mitochondria- supports ferroptosis. The opposite effect on ferroptosis by silencing either the E1 or the E3 subunit of the pyruvate dehydrogenase complex pointed out the autoxidation of dihydrolipoamide as the source of superoxide. We finally observed that GSH depletion activates superoxide production, seemingly through the inhibition of the specific kinase that inhibits pyruvate dehydrogenase. In summary, this set of data is compatible with a scenario where the more electrophilic status produced by GSH depletion not only activates ferroptosis by preventing GPx4 activity, but also favors the formation of lipid hydroperoxides. In an attractive perspective of tissue homeostasis, it is the activation of energetic metabolism associated to a decreased nucleophilic tone that, besides supporting energy demanding proliferation, also sensitizes cells to a regulated form of death.

Costs of irritable bowel syndrome in European countries with universal healthcare coverage: a meta-analysis

OBJECTIVE

To provide an overall estimate of the direct, indirect and total costs of irritable bowel syndrome (IBS) for the adult population of the European countries with universal healthcare coverage.

MATERIALS AND METHODS

We searched MedLine and Scopus databases (up to September 2018) to identify the European studies that evaluated the economic impact of IBS. Mean annual direct, indirect and total per-capita IBS costs were estimated using random-effect single-group meta-analyses of continuous data. All analyses were stratified by payer category (governments, insurance, societal), and the results were expressed as summary mean and 95% CI.

RESULTS

A total of 24 studies were included in the meta-analyses. Only two studies evaluated IBS costs in Italy. The pooled summary of direct IBS per-capita cost, obtained from 23 European datasets (n=15,157), was €1837/year (95% CI: 1480-2195), with large differences across payers (from €1183 to €3358, in countries with publicly-funded and insurance-based health systems, respectively). The mean indirect cost, extracted from 13 datasets (n=3978), was €2314/year (95% CI: 1811-2817), again with wide differences across payers. Finally, the meta-analysis estimating the total annual cost, based upon 11 European datasets (n=2757), yielded a summary estimate of €2889/year (95% CI: 2318-3460) per patient, ranging from €1602 (insurance-based health systems) to €3909 (studies adopting a societal perspective).

CONCLUSIONS

Considering a conservative estimate of 2,736,700 Italian adults affected by the syndrome, the minimum costs due to IBS in Italy - likely underestimated - range from 6 to 8 billion euro per year. Given the substantial economic burden for patients, healthcare systems and society, IBS should be included among the priorities of the public health agenda.

Lipid peroxidation and ferroptosis: The role of GSH and GPx4

Ferroptosis (FPT) is a form of cell death due to missed control of membrane lipid peroxidation (LPO). According to the axiomatic definition of non-accidental cell death, LPO takes place in a scenario of altered homeostasis. FPT, differently from apoptosis, occurs in the absence of any known specific genetically encoded death pathway or specific agonist, and thus must be rated as a regulated, although not "programmed", death pathway. It follows that LPO is under a homeostatic metabolic control and is only permitted when indispensable constraints are satisfied and the antiperoxidant machinery collapses. The activity of the selenoperoxidase Glutathione Peroxidase 4 (GPx4) is the cornerstone of the antiperoxidant defence. Converging evidence on both mechanism of LPO and GPx4 enzymology indicates that LPO is initiated by alkoxyl radicals produced by ferrous iron from the hydroperoxide derivatives of lipids (LOOH), traces of which are the unavoidable drawback of aerobic metabolism. FPT takes place when a threshold has been exceeded. This occurs when the major conditions are satisfied: i) oxygen metabolism leading to the continuous formation of traces of LOOH from phospholipid-containing polyunsaturated fatty acids; ii) missed enzymatic reduction of LOOH; iii) availability of ferrous iron from the labile iron pool. Although the effectors impacting on homeostasis and leading to FPT in physiological conditions are not known, from the available knowledge on LPO and GPx4 enzymology we propose that it is aerobic life itself that, while supporting bioenergetics, is also a critical requisite of FPT. Yet, when the homeostatic control of the steady state between LOOH formation and reduction is lost, LPO is activated and FPT is executed.

A dual attack on the peroxide bond. The common principle of peroxidatic cysteine or selenocysteine residues

The (seleno)cysteine residues in some protein families react with hydroperoxides with rate constants far beyond those of fully dissociated low molecular weight thiol or selenol compounds. In case of the glutathione peroxidases, we could demonstrate that high rate constants are achieved by a proton transfer from the chalcogenol to a residue of the active site [Orian et al. Free Radic. Biol. Med. 87 (2015)]. We extended this study to three more protein families (OxyR, GAPDH and Prx). According to DFT calculations, a proton transfer from the active site chalcogenol to a residue within the active site is a prerequisite for both, creating a chalcogenolate that attacks one oxygen of the hydroperoxide substrate and combining the delocalized proton with the remaining OH or OR, respectively, to create an ideal leaving group. The “parking postions” of the delocalized proton differ between the protein families. It is the ring nitrogen of tryptophan in GPx, a histidine in GAPDH and OxyR and a threonine in Prx. The basic principle, however, is common to all four families of proteins. We, thus, conclude that the principle outlined in this investigation offers a convincing explanation for how a cysteine residue can become peroxidatic.

•

In some protein families, (seleno)cysteine residues react with hydroperoxides with very high rate constants.

•

In GPx, DFT models of the oxidation of the catalytic site support a two-step mechanism for the H₂O₂ reduction.

•

This mechanism is here found to operate in other thiol-based enzymes, i.e. OxyR, GAPDH and Prx.

Chronobiology of acute pancreatitis in a single Italian centre

OBJECTIVE

Seasonal variation may occur in many different diseases hence influencing awareness in clinical practice. This study aimed to establish seasonal variations of acute pancreatitis by using a validated chronobiological analysis.

PATIENTS AND METHODS

All cases of acute pancreatitis consecutively observed in fifteen years, i.e., from January 2003 to December 2017, at St. Anna University Hospital of Ferrara, Italy, were included in this study. Accurate statistical and logistic regression analyses were applied to our database.

RESULTS

A total number of 1883 consecutive cases of acute pancreatitis were observed. A significant peak was identified in the summer period (p=0.014). Patient stratification, according to age, showed that elderly people had an increased incidence of acute pancreatitis in autumn and summer (being the biliary stone disease the main cause, p=0.011) vs. other seasons (p=0.003). Mortality occurred more prominently in males vs. females, although the latter gender was more prone to acute pancreatitis (p=0.017).

CONCLUSIONS

In a single centre of Northern East of Italy, we demonstrated that acute pancreatitis had a clear seasonal variation with a prominent incidence during summer. Various associated factors could contribute to this chronobiological pattern, including gender, age, and biliary stone disease.

Lack of glutathione peroxidase-8 in the ER impacts on lipid composition of HeLa cells microsomal membranes

GPx8 is a glutathione peroxidase homolog inserted in the membranes of endoplasmic reticulum (ER), where it seemingly plays a role in controlling redox status by preventing the spill of H₂O₂. We addressed the impact of GPx8 silencing on the lipidome of microsomal membranes, using stably GPx8-silenced HeLa cells. The two cell lines were clearly separated by Principal Component Analysis (PCA) and Partial Least Square Discriminant analysis (PLS-DA) of lipidome. Considering in detail the individual lipid classes, we observed that unsaturated glycerophospholipids (GPL) decreased, while only in phosphatidylinositols (PI) a substitution of monounsaturated fatty acids (MUFA) for polyunsaturated fatty acids (PUFA) was observed. Among sphingolipids (SL), ceramides (CER) decreased while sphingomyelins (SM) and neutral glycophingolipids (nGSL) increased. Here, in addition, longer chains than in controls in the amide fatty acid were present. The increase up to four folds of the CER (d18:1; c24:0) containing three hexose units, was the most remarkable species increasing in the differential lipidome of siGPx8 cells. Quantitative RT-PCR complied with lipidomic analysis specifically showing an increased expression of: i) acyl-CoA synthetase 5 (ACSL5); ii) CER synthase 2 and 4; iii) CER transporter (CERT); iv) UDP-glucosyl transferase (UDP-GlcT), associated to a decreased expression of UDP-galactosyl transferase (UDP-GalT). A role of the unfolded protein response (UPR) and the spliced form of the transcription factor XBP1 on the transcriptional changes of GPx8 silenced cells was ruled-out. Similarly, also the involvement of Nrf2 and NF-κB. Altogether our results indicate that GPx8-silencing of HeLa yields a membrane depleted by about 24% of polyunsaturated GPL and a corresponding increase of saturated or monounsaturated SM and specific nGSL. This is tentatively interpreted as an adaptive mechanism leading to an increased resistance to radical oxidations. Moreover, the marked shift of fatty acid composition of PI emerges as a possibly relevant issue in respect to the impact of GPx8 on signaling pathways.

Insight into the mechanism of ferroptosis inhibition by ferrostatin-1

Ferroptosis is a form of cell death primed by iron and lipid hydroperoxides and prevented by GPx4. Ferrostatin-1 (fer-1) inhibits ferroptosis much more efficiently than phenolic antioxidants. Previous studies on the antioxidant efficiency of fer-1 adopted kinetic tests where a diazo compound generates the hydroperoxyl radical scavenged by the antioxidant. However, this reaction, accounting for a chain breaking effect, is only minimally useful for the description of the inhibition of ferrous iron and lipid hydroperoxide dependent peroxidation. Scavenging lipid hydroperoxyl radicals, indeed, generates lipid hydroperoxides from which ferrous iron initiates a new peroxidative chain reaction. We show that when fer-1 inhibits peroxidation, initiated by iron and traces of lipid hydroperoxides in liposomes, the pattern of oxidized species produced from traces of pre-existing hydroperoxides is practically identical to that observed following exhaustive peroxidation in the absence of the antioxidant. This supported the notion that the anti-ferroptotic activity of fer-1 is actually due to the scavenging of initiating alkoxyl radicals produced, together with other rearrangement products, by ferrous iron from lipid hydroperoxides. Notably, fer-1 is not consumed while inhibiting iron dependent lipid peroxidation. The emerging concept is that it is ferrous iron itself that reduces fer-1 radical. This was supported by electroanalytical evidence that fer-1 forms a complex with iron and further confirmed in cells by fluorescence of calcein, indicating a decrease of labile iron in the presence of fer-1. The notion of such as pseudo-catalytic cycle of the ferrostatin-iron complex was also investigated by means of quantum mechanics calculations, which confirmed the reduction of an alkoxyl radical model by fer-1 and the reduction of fer-1 radical by ferrous iron. In summary, GPx4 and fer-1 in the presence of ferrous iron, produces, by distinct mechanism, the most relevant anti-ferroptotic effect, i.e the disappearance of initiating lipid hydroperoxides.

Benextramine and derivatives as novel human monoamine oxidases inhibitors: an integrated approach

The two human monoamine oxidase isoforms (namely MAO A and MAO B) are enzymes involved in the catabolism of monoamines, including neurotransmitters, and for this reason are well-known and attractive pharmacological targets in neuropsychiatric and neurodegenerative diseases, for which novel pharmacological approaches are necessary. Benextramine is a tetraamine disulfide mainly known as irreversible α-adrenergic antagonist, but able to hit additional targets involved in neurodegeneration. As the molecular structures of monoamine oxidases contain nine cysteine residues, the aim of this study was to evaluate benextramine and eleven structurally related polyamine disulfides as potential MAO inhibitors. Most of the compounds were found to induce irreversible inactivation of MAOs with inactivation potency depending on both the polyamine structure and the enzyme isoform. The more effective compounds generally showed preference for MAO B. Structure-activity relationships studies revealed the key role played by the disulfide core of these molecules in the inactivation mechanism. Docking experiments pointed to Cys323, in MAO A, and Cys172, in MAO B, as target of this type of inhibitors thus suggesting that their covalent binding inside the MAO active site sterically impedes the entrance of substrate towards the FAD cofactor. The effectiveness of benextramine in inactivating MAOs was demonstrated in SH-SY5Y neuroblastoma cell line. These results demonstrated for the first time that benextramine and its derivatives can inactivate human MAOs exploiting a mechanism different from that of the classical MAO inhibitors and could be a starting point for the development of pharmacological tools in neurodegenerative diseases.

Rust never sleeps: The continuing story of the Iron Bolt

Since 1981, Gordon Research Conferences have been held on the topic of Oxygen Radicals on a biennial basis, to highlight and discuss the latest cutting edge research in this area. Since the first meeting, one special feature of this conference has been the awarding of the so-called Iron Bolt, an award that started in jest but has gained increasing reputation over the years. Since no written documentation exists for this Iron Bolt award, this perspective serves to overview the history of this unusual award, and highlights various experiences of previous winners of this "prestigious" award and other interesting anecdotes.

GPx4, Lipid Peroxidation, and Cell Death: Discoveries, Rediscoveries, and Open Issues

SIGNIFICANCE

Iron-dependent lipid peroxidation is a complex oxidative process where phospholipid hydroperoxides (PLOOH) are produced in membranes and finally transformed into a series of decomposition products, some of which are endowed with biological activity. It is specifically prevented by glutathione peroxidase 4 (GPx4), the selenoenzyme that reduces PLOOH by glutathione (GSH). PLOOH is both a product and the major initiator of peroxidative chain reactions, as well as an activator of lipoxygenases. α-Tocopherol both specifically breaks peroxidative chain propagation and inhibits lipoxygenases. Thus, GPx4, GSH, and α-tocopherol are integrated in a concerted anti-peroxidant mechanism. Recent Advances: Ferroptosis has been recently identified as a cell death subroutine that is specifically activated by missing GPx4 activity and inhibited by iron chelation or α-tocopherol supplementation. Ferroptosis induction may underlie spontaneous human diseases, such as major neurodegeneration and neuroinflammation, causing an excessive cell death. The basic mechanism of ferroptosis, therefore, fits the features of activation of lipid peroxidation.

CRITICAL ISSUES

Still lacking are convincing proofs that lipoxygenases are involved in ferroptosis. Also, unknown are the molecules eventually killing cells and the mechanisms underlying the drop of the cellular anti-peroxidant capacity.

FUTURE DIRECTIONS

Molecular events and mechanisms of ferroptosis to be unraveled and validated on animal models are GPx4 inactivation, role of GSH concentration, increased iron availability, and membrane structure and composition. This is expected to drive drug discovery that is aimed at halting cell death in degenerative diseases or boosting it in cancer cells. Antioxid. Redox Signal. 29, 61-74.

Phytosome complex of curcumin as complementary therapy of advanced pancreatic cancer improves safety and efficacy of gemcitabine: Results of a prospective phase II trial

A large body of biomedical evidence indicates that activation of Nrf2 by curcumin increases the nucleophilic tone and damps inflammation cumulatively supporting the malignant phenotype. Conversely, genetic analyses suggest a possible oncogenic nature of constitutive Nrf2 activation since an increased nucleophilic tone is alleged increasing chemoresistance of cancer cells. Aiming to contribute to solve this paradox, this study addressed the issue of safety and efficacy of curcumin as complementary therapy of gemcitabine on pancreatic cancer. This was a single centre, single arm prospective phase II trial. Patients received gemcitabine and Meriva^®, a patented preparation of curcumin complexed with phospholipids. Primary endpoint was response rate, secondary endpoints were progression free survival, overall survival, tolerability and quality of life. Analysis of inflammatory biomarkers was also carried out. Fifty-two consecutive patients were enrolled. Forty-four (13 locally advanced and 31 metastatic) were suitable for primary endpoint evaluation. Median age was 66 years (range 42-87); 42 patients had Eastern Cooperative Oncology Group performance status 0-1. The median number of treatment cycle was 4.5 (range 2-14). We observed 27.3% of response rate and 34.1% of cases with stable disease, totalizing a disease control rate of 61.4%. The median progression free survival and overall survival were 8.4 and 10.2 months, respectively. Higher IL-6 and sCD40L levels before treatment were associated to a worse overall survival (p < 0.01). Increases in sCD40L levels after 1 cycle of chemotherapy were associated with a reduced response to the therapy. Grade 3/4 toxicity was observed (neutropenia, 38.6%; anemia, 6.8%). There were no significant changes in quality of life during therapy. In conclusion, the complementary therapy to gemcitabine with phytosome complex of curcumin is not only safe but also efficiently translate in a good response rate in first line therapy of advanced pancreatic cancer.

The Oxygen Paradox, the French Paradox, and age-related diseases

A paradox is a seemingly absurd or impossible concept, proposition, or theory that is often difficult to understand or explain, sometimes apparently self-contradictory, and yet ultimately correct or true. How is it possible, for example, that oxygen "a toxic environmental poison" could be also indispensable for life (Beckman and Ames Physiol Rev 78(2):547-81, 1998; Stadtman and Berlett Chem Res Toxicol 10(5):485-94, 1997)?: the so-called Oxygen Paradox (Davies and Ursini 1995; Davies Biochem Soc Symp 61:1-31, 1995). How can French people apparently disregard the rule that high dietary intakes of cholesterol and saturated fats (e.g., cheese and paté) will result in an early death from cardiovascular diseases (Renaud and de Lorgeril Lancet 339(8808):1523-6, 1992; Catalgol et al. Front Pharmacol 3:141, 2012; Eisenberg et al. Nat Med 22(12):1428-1438, 2016)?: the so-called, French Paradox. Doubtless, the truth is not a duality and epistemological bias probably generates apparently self-contradictory conclusions. Perhaps nowhere in biology are there so many apparently contradictory views, and even experimental results, affecting human physiology and pathology as in the fields of free radicals and oxidative stress, antioxidants, foods and drinks, and dietary recommendations; this is particularly true when issues such as disease-susceptibility or avoidance, "healthspan," "lifespan," and ageing are involved. Consider, for example, the apparently paradoxical observation that treatment with low doses of a substance that is toxic at high concentrations may actually induce transient adaptations that protect against a subsequent exposure to the same (or similar) toxin. This particular paradox is now mechanistically explained as "Adaptive Homeostasis" (Davies Mol Asp Med 49:1-7, 2016; Pomatto et al. 2017a; Lomeli et al. Clin Sci (Lond) 131(21):2573-2599, 2017; Pomatto and Davies 2017); the non-damaging process by which an apparent toxicant can activate biological signal transduction pathways to increase expression of protective genes, by mechanisms that are completely different from those by which the same agent induces toxicity at high concentrations. In this review, we explore the influences and effects of paradoxes such as the Oxygen Paradox and the French Paradox on the etiology, progression, and outcomes of many of the major human age-related diseases, as well as the basic biological phenomenon of ageing itself.

Glutathione peroxidase 4-catalyzed reduction of lipid hydroperoxides in membranes: The polar head of membrane phospholipids binds the enzyme and addresses the fatty acid hydroperoxide group toward the redox center

GPx4 is a monomeric glutathione peroxidase, unique in reducing the hydroperoxide group (-OOH) of fatty acids esterified in membrane phospholipids. This reaction inhibits lipid peroxidation and accounts for enzyme's vital role. Here we investigated the interaction of GPx4 with membrane phospholipids. A cationic surface near the GPx4 catalytic center interacts with phospholipid polar heads. Accordingly, SPR analysis indicates cardiolipin as the phospholipid with maximal affinity to GPx4. Consistent with the electrostatic nature of the interaction, KCl increases the K_D. Molecular dynamic (MD) simulation shows that a -OOH posed in the core of the membrane as 13 - or 9 -OOH of tetra-linoleoyl cardiolipin or 15 -OOH stearoyl-arachidonoyl-phosphaphatidylcholine moves to the lipid-water interface. Thereby, the -OOH groups are addressed toward the GPx4 redox center. In this pose, however, the catalytic site facing the membrane would be inaccessible to GSH, but the consecutive redox processes facilitate access of GSH, which further primes undocking of the enzyme, because GSH competes for the binding residues implicated in docking. During the final phase of the catalytic cycle, while GSSG is produced, GPx4 is disconnected from the membrane. The observation that GSH depletion in cells induces GPx4 translocation to the membrane, is in agreement with this concept.

European contribution to the study of ROS: A summary of the findings and prospects for the future from the COST action BM1203 (EU-ROS)

The European Cooperation in Science and Technology (COST) provides an ideal framework to establish multi-disciplinary research networks. COST Action BM1203 (EU-ROS) represents a consortium of researchers from different disciplines who are dedicated to providing new insights and tools for better understanding redox biology and medicine and, in the long run, to finding new therapeutic strategies to target dysregulated redox processes in various diseases. This report highlights the major achievements of EU-ROS as well as research updates and new perspectives arising from its members. The EU-ROS consortium comprised more than 140 active members who worked together for four years on the topics briefly described below. The formation of reactive oxygen and nitrogen species (RONS) is an established hallmark of our aerobic environment and metabolism but RONS also act as messengers via redox regulation of essential cellular processes. The fact that many diseases have been found to be associated with oxidative stress established the theory of oxidative stress as a trigger of diseases that can be corrected by antioxidant therapy. However, while experimental studies support this thesis, clinical studies still generate controversial results, due to complex pathophysiology of oxidative stress in humans. For future improvement of antioxidant therapy and better understanding of redox-associated disease progression detailed knowledge on the sources and targets of RONS formation and discrimination of their detrimental or beneficial roles is required. In order to advance this important area of biology and medicine, highly synergistic approaches combining a variety of diverse and contrasting disciplines are needed.

Protein cysteine oxidation in redox signaling: Caveats on sulfenic acid detection and quantification

Oxidation of critical signaling protein cysteines regulated by H₂O₂ has been considered to involve sulfenic acid (RSOH) formation. RSOH may subsequently form either a sulfenyl amide (RSNHR') with a neighboring amide, or a mixed disulfide (RSSR') with another protein cysteine or glutathione. Previous studies have claimed that RSOH can be detected as an adduct (e.g., with 5,5-dimethylcyclohexane-1,3-dione; dimedone). Here, kinetic data are discussed which indicate that few proteins can form RSOH under physiological signaling conditions. We also present experimental evidence that indicates that (1) dimedone reacts rapidly with sulfenyl amides, and more rapidly than with sulfenic acids, and (2) that disulfides can react reversibly with amides to form sulfenyl amides. As some proteins are more stable as the sulfenyl amide than as a glutathionylated species, the former may account for some of the species previously identified as the "sulfenome" - the cellular complement of reversibly-oxidized thiol proteins generated via sulfenic acids.

Selenoprotein Gene Nomenclature

The human genome contains 25 genes coding for selenocysteine-containing proteins (selenoproteins). These proteins are involved in a variety of functions, most notably redox homeostasis. Selenoprotein enzymes with known functions are designated according to these functions: TXNRD1, TXNRD2, and TXNRD3 (thioredoxin reductases), GPX1, GPX2, GPX3, GPX4, and GPX6 (glutathione peroxidases), DIO1, DIO2, and DIO3 (iodothyronine deiodinases), MSRB1 (methionine sulfoxide reductase B1), and SEPHS2 (selenophosphate synthetase 2). Selenoproteins without known functions have traditionally been denoted by SEL or SEP symbols. However, these symbols are sometimes ambiguous and conflict with the approved nomenclature for several other genes. Therefore, there is a need to implement a rational and coherent nomenclature system for selenoprotein-encoding genes. Our solution is to use the root symbol SELENO followed by a letter. This nomenclature applies to SELENOF (selenoprotein F, the 15-kDa selenoprotein, SEP15), SELENOH (selenoprotein H, SELH, C11orf31), SELENOI (selenoprotein I, SELI, EPT1), SELENOK (selenoprotein K, SELK), SELENOM (selenoprotein M, SELM), SELENON (selenoprotein N, SEPN1, SELN), SELENOO (selenoprotein O, SELO), SELENOP (selenoprotein P, SeP, SEPP1, SELP), SELENOS (selenoprotein S, SELS, SEPS1, VIMP), SELENOT (selenoprotein T, SELT), SELENOV (selenoprotein V, SELV), and SELENOW (selenoprotein W, SELW, SEPW1). This system, approved by the HUGO Gene Nomenclature Committee, also resolves conflicting, missing, and ambiguous designations for selenoprotein genes and is applicable to selenoproteins across vertebrates.

Redox status in a model of cancer stem cells

Reversible oxidation of Cys residues is a crucial element of redox homeostasis and signaling. According to a popular concept in oxidative stress signaling, the oxidation of targets of signals can only take place following an overwhelming of the cellular antioxidant capacity. This concept, however, ignores the activation of feedback mechanisms possibly leading to a paradoxical effect. In a model of cancer stem cells (CSC), stably overexpressing the TAZ oncogene, we observed that the increased formation of oxidants is associated with a globally more reduced state of proteins. Redox proteomics revealed that several proteins, capable of undergoing reversible redox transitions, are indeed more reduced while just few are more oxidized. Among the proteins more oxidized, G6PDH emerges as both more expressed and activated by oxidation. This accounts for the observed more reduced state of the NADPH/NADP⁺ couple. The dynamic redox flux generating this apparently paradoxical effect is rationalized in a computational system biology model highlighting the crucial role of G6PDH activity on the rate of redox transitions eventually leading to the reduction of reversible redox switches.

Effects of moderate beer consumption on health and disease: A consensus document

A large evidence-based review on the effects of a moderate consumption of beer on human health has been conducted by an international panel of experts who reached a full consensus on the present document. Low-moderate (up to 1 drink per day in women, up to 2 in men), non-bingeing beer consumption, reduces the risk of cardiovascular disease. This effect is similar to that of wine, at comparable alcohol amounts. Epidemiological studies suggest that moderate consumption of either beer or wine may confer greater cardiovascular protection than spirits. Although specific data on beer are not conclusive, observational studies seem to indicate that low-moderate alcohol consumption is associated with a reduced risk of developing neurodegenerative disease. There is no evidence that beer drinking is different from other types of alcoholic beverages in respect to risk for some cancers. Evidence consistently suggests a J-shaped relationship between alcohol consumption (including beer) and all-cause mortality, with lower risk for moderate alcohol consumers than for abstainers or heavy drinkers. Unless they are at high risk for alcohol-related cancers or alcohol dependency, there is no reason to discourage healthy adults who are already regular light-moderate beer consumers from continuing. Consumption of beer, at any dosage, is not recommended for children, adolescents, pregnant women, individuals at risk to develop alcoholism, those with cardiomyopathy, cardiac arrhythmias, depression, liver and pancreatic diseases, or anyone engaged in actions that require concentration, skill or coordination. In conclusion, although heavy and excessive beer consumption exerts deleterious effects on the human body, with increased disease risks on many organs and is associated to significant social problems such as addiction, accidents, violence and crime, data reported in this document show evidence for no harm of moderate beer consumption for major chronic conditions and some benefit against cardiovascular disease.

Redox homeostasis: The Golden Mean of healthy living

The notion that electrophiles serve as messengers in cell signaling is now widely accepted. Nonetheless, major issues restrain acceptance of redox homeostasis and redox signaling as components of maintenance of a normal physiological steady state. The first is that redox signaling requires sudden switching on of oxidant production and bypassing of antioxidant mechanisms rather than a continuous process that, like other signaling mechanisms, can be smoothly turned up or down. The second is the misperception that reactions in redox signaling involve “reactive oxygen species” rather than reaction of specific electrophiles with specific protein thiolates. The third is that hormesis provides protection against oxidants by increasing cellular defense or repair mechanisms rather than by specifically addressing the offset of redox homeostasis. Instead, we propose that both oxidant and antioxidant signaling are main features of redox homeostasis. As the redox shift is rapidly reversed by feedback reactions, homeostasis is maintained by continuous signaling for production and elimination of electrophiles and nucleophiles. Redox homeostasis, which is the maintenance of nucleophilic tone, accounts for a healthy physiological steady state. Electrophiles and nucleophiles are not intrinsically harmful or protective, and redox homeostasis is an essential feature of both the response to challenges and subsequent feedback. While the balance between oxidants and nucleophiles is preserved in redox homeostasis, oxidative stress provokes the establishment of a new radically altered redox steady state. The popular belief that scavenging free radicals by antioxidants has a beneficial effect is wishful thinking. We propose, instead, that continuous feedback preserves nucleophilic tone and that this is supported by redox active nutritional phytochemicals. These nonessential compounds, by activating Nrf2, mimic the effect of endogenously produced electrophiles (parahormesis). In summary, while hormesis, although globally protective, results in setting up of a new phenotype, parahormesis contributes to health by favoring maintenance of homeostasis.

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Redox homeostasis is the continuously challenged oxidative/nucleophilic balance.

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Rheostatic redox signaling enzymes maintain oxidative/nucleophilic homeostasis.

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Phytochemicals assist redox homeostasis through oxidative feedback (parahormesis).

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Adaptation and hormesis while protective establish a new phenotype and set point.

Selenocysteine oxidation in glutathione peroxidase catalysis: an MS-supported quantum mechanics study

Glutathione peroxidases (GPxs) are enzymes working with either selenium or sulfur catalysis. They adopted diverse functions ranging from detoxification of H(2)O(2) to redox signaling and differentiation. The relative stability of the selenoenzymes, however, remained enigmatic in view of the postulated involvement of a highly unstable selenenic acid form during catalysis. Nevertheless, density functional theory calculations obtained with a representative active site model verify the mechanistic concept of GPx catalysis and underscore its efficiency. However, they also allow that the selenenic acid, in the absence of the reducing substrate, reacts with a nitrogen in the active site. MS/MS analysis of oxidized rat GPx4 complies with the predicted structure, an 8-membered ring, in which selenium is bound as selenenylamide to the protein backbone. The intermediate can be re-integrated into the canonical GPx cycle by glutathione, whereas, under denaturing conditions, its selenium moiety undergoes β-cleavage with formation of a dehydro-alanine residue. The selenenylamide bypass prevents destruction of the redox center due to over-oxidation of the selenium or its elimination and likely allows fine-tuning of GPx activity or alternate substrate reactions for regulatory purposes.

Understanding mammalian glutathione peroxidase 7 in the light of its homologs

The glutathione peroxidase homologs (GPxs) efficiently reduce hydroperoxides using electrons from glutathione (GSH), thioredoxin (Trx), or protein disulfide isomerase (PDI). Trx is preferentially used by the GPxs of the majority of bacteria, invertebrates, plants, and fungi. GSH or PDI, instead, is preferentially used by vertebrate GPxs that operate by Sec or Cys catalysis, respectively. Mammalian GPx7 and GPx8 are unique homologs that contain a peroxidatic Cys (CP). Being reduced by PDI and located within the endoplasmic reticulum (ER), these enzymes have been involved in oxidative protein folding. Kinetic analysis indicates that oxidation of PDI by recombinant GPx7 occurs at a much faster rate than that of GSH. Nonetheless, activity measurement suggests that, at physiological concentrations, a competition between these two substrates takes place, with the rate of PDI oxidation by GPx7 controlled by the concentration of GSH, whereas the GSSG produced in the competing reaction contributes to the ER redox buffer. A mechanism has been proposed for GPx7 involving two Cys residues, in which an intramolecular disulfide of the CP is formed with an alleged resolving Cys (CR) located in the strongly conserved FPCNQ motif (C86 in humans), a noncanonical position in GPxs. Kinetic measurements and comparison with the other thiol peroxidases containing a functional CR suggest that a resolving function of C86 in the catalytic cycle is very unlikely. We propose that GPx7 is catalytically active as a 1-Cys-GPx, in which CP both reduces H2O2 and oxidizes PDI, and that the CP-C86 disulfide has instead the role of stabilizing the oxidized peroxidase in the absence of the reducing substrate.

Expression of a Catalytically Inactive Mutant Form of Glutathione Peroxidase 4 (Gpx4) Confers a Dominant-negative Effect in Male Fertility

The selenoenzyme Gpx4 is essential for early embryogenesis and cell viability for its unique function to prevent phospholipid oxidation. Recently, the cytosolic form of Gpx4 was identified as an upstream regulator of a novel form of non-apoptotic cell death, called ferroptosis, whereas the mitochondrial isoform of Gpx4 was previously shown to be crucial for male fertility. Here, we generated and analyzed mice with a targeted mutation of the active site selenocysteine of Gpx4 (Gpx4_U46S). Mice homozygous for Gpx4_U46S died at the same embryonic stage (E7.5) as Gpx4(-/-) embryos as expected. Surprisingly, male mice heterozygous for Gpx4_U46S presented subfertility. Subfertility was manifested in a reduced number of litters from heterozygous breeding and an impairment of spermatozoa to fertilize oocytes in vitro. Morphologically, sperm isolated from heterozygous Gpx4_U46S mice revealed many structural abnormalities particularly in the spermatozoa midpiece due to improper oxidation and polymerization of sperm capsular proteins and malformation of the mitochondrial capsule surrounding and stabilizing sperm mitochondria. These findings are reminiscent of sperm isolated from selenium-deprived rodents or from mice specifically lacking mitochondrial Gpx4. Due to a strongly facilitated incorporation of Ser in the polypeptide chain as compared with selenocysteine at the UGA codon, expression of the catalytically inactive Gpx4_U46S was found to be strongly increased. Because the stability of the mitochondrial capsule of mature spermatozoa depends on the moonlighting function of Gpx4 both as an enzyme oxidizing capsular protein thiols and as a structural protein, tightly controlled expression of functional Gpx4 emerges as a key for full male fertility.