Factors relacionats amb el manteniment de la inflamació i l'oclusió vascular. Implicacions en l'evolució dels pacients amb arteritis de cèl·lules gegants.

[cat] L'arteritis de cèl·lules gegants (ACG) és una vasculitis sistèmica de caràcter granulomatós que afecta vasos de calibre mitjà i gran. Per aprofundir en els mecanismes que intervenen en el desenvolupament de la hiperplasia intimal i la inflamació en l'ACG, vam dissenyar un nou mètode d'obtenció de cèl·lules miointimals (HTAMC) a partir de biòpsies d'artèries temporals dels pacients. Vam analitzar l'efecte de PDGF-AB, FGF-2, VEGF, EGF, TGFβ, CCL2, IL-6 i IL-1β sobre la proliferació i migració de les HTAMC. El PDGF va ser el principal agent mitogènic, seguit pel FGF-2. Respecte a la migració, només el PDGF i l'EGF van demostrar una acció quimiotàctica. Probablement el comportament d'aquestes cèl·lules in vivo és el resultat d'un balanç de diferents estímuls, per tant, caldrà plantejar-se el disseny de teràpies dirigides i combinades.Donat que el PDGF va ésser el factor que més influencia el comportament de les HTAMC, vam estudiar els efectes de l'imatinib mesylate (Gleevec®), un inhibidor del receptor del PDGF. Vam demostrar que l'imatinib bloqueja les vies de senyalització del PDGF, i conseqüentment, inhibeix la proliferació i la migració de les HTAMC estimulades amb PDGF. També vam estudiar altres funcions del PDGF i vam observar que incrementa l'expressió dels col·làgens tipus I i III i també augmenta la producció de fibronectina en les HTAMC. L'imatinib va inhibir l'estimulació en la producció d'aquestes proteïnes de matriu extracel·lular. D'altra banda, vam demostrar que el PDGF estimulava la secreció de CCL2 i d'angiogenina en les HTAMC i que l'imatinib contrarestava també aquests efectes. Donat que no es disposa d'un model animal de la malaltia, el cultiu de seccions d'artèria temporal sobre Matrigel® és un mètode que ens permet analitzar tota la complexitat d'aquest sistema, ja que conté tots els tipus cel·lulars de l'artèria més l'infiltrat inflamatori. Als set dies, s'inicia el creixement de les HTAMC fins a formar un cultiu confluent. L'imatinib inhibeix el creixement de les HTAMC a partir de l'artèria. Aquests resultats in vitro i ex vivo són encoratjadors demostrant que l'imatinib podria ser terapèuticament útil per contrarestar el procés inflamatori i el desenvolupament de la hiperplàsia intimal que es produeix en les artèries en l'ACG, però només un assaig clínic podria comprovar la utilitat de l'imatinib in vivo.En el segon estudi ens vam plantejar esbrinar quin és el paper de l'endotelina (ET) en l'ACG. Primerament, vam quantificar els nivells d'ET en el plasma dels pacients i van concloure que els pacients que patien fenòmens isquèmics tenien significativament més ET circulant que els que no tenien aquestes complicacions. A les biòpsies d'artèria temporal, els pacients van presentar nivells més alts de totes les proteïnes del sistema (ET-1, ECE-1 i ambdós receptors A i B). Mentre que a nivell d'expressió d'ARNm, els pacients tenien nivells més baixos de tots els components. Davant d'aquesta regulació negativa de tot el sistema, ens vam plantejar l'existència d'un mecanisme de retroalimentació negativa degut a l'excés d'ET. Els experiments in vitro amb cèl·lules endotelials i miointimals van demostrar que l'ET no regula negativament la seva pròpia expressió. En canvi, el PDGF i l'IL1β van regular negativament l'expressió de l'ARNm de l'ET en HTAMC.Als pacients tractats durant 8 dies de mitjana amb glucocorticoides, el tractament d'elecció de l'ACG, va disminuir l'ECE-1 i ETAR però no van disminuir els nivells d'ET-1, que és la molècula amb activitat funcional vasoconstrictora. Les nostres dades experimentals indiquen que el PDGF i l'endotelina poden estar implicats en la progressió de les lesions arterials dels pacients amb ACG i pensem que aquests resultats poden ser útils pel disseny d'assaigs clínics de teràpies més dirigides.[eng] Giant Cell Arteritis (GCA) is a chronic inflammatory disease involving large and medium-sized vessels. Vascular remodeling in response to inflammation leads to intimal hyperplasia resulting in lumen occlusion and ischemia of supplied tissues. To gain a better understanding of the mechanisms leading to vascular occlusion in GCA, we developed a system to obtain and culture myointimal cells from temporal arteries (HTAMC) in order to assess the effects of various mediators on proliferation, migration and extracellular matrix production. Among the factors tested, PDGF exhibited the strongest activity in our system. Given that imatinib mesylate is an inhibitor of the PDGF receptor, we tested the effect of this compound in our model. We found that imatinib inhibited HTAMC biologic responses related to the development of intimal hyperplasia. Our findings suggest that imatinib might be a therapeutic option to limit occlusive vasculopathy in large-vessel vasculitis.Fifteen to 20% of our patients develop vascular occlusive events often preceded by transient ischemia. The aims of the second study were to investigate the expression of the endothelin (ET) system in GCA lesions, to assess its relationship with the development of ischemic complications, and to analyze the effects of glucocorticoid treatment on this system.Plasma ET was significantly elevated in GCA patients with ischemic complications. ET-1, endothelin converting enzyme (ECE-1) and both ET receptors (ETAR and ETBR) were increased in temporal arteries from GCA patients compared to controls. Intriguingly, mRNA expression of ET-1, ECE-1 and both receptors was significantly reduced in GCA patients. In order to investigate mechanisms underlying these results, we performed in vitro studies with endothelial cells and HTAMC. ET did not downregulate its own expression. In contrast, PDGF and IL-1β decreased ET expression by HTAMC. Glucocorticoid treatment for 8 days did not efficiently result in decreased ET concentration in tissue. In conclusion, the expression of the ET system components is increased at the protein level in GCA lesions creating a microenvironment prone to development of vasoconstrictive occlusive events which may contribute to ischemic complications. Recovery induced by glucocorticoids is not complete, indicating persistent exposure to the effects of ET during initial treatment

Two Novel Variants in YARS2 Gene Are Responsible for an Extended MLASA Phenotype with Pancreatic Insufficiency

Pathogenic variants in the mitochondrial tyrosyl-tRNA synthetase gene (YARS2) were associated with myopathy, lactic acidosis, and sideroblastic anemia (MLASA). However, patients can present mitochondrial myopathy, with exercise intolerance and muscle weakness, leading from mild to lethal phenotypes. Genes implicated in mtDNA replication were studied by Next Gener ation Sequencing (NGS) and whole exome sequence with the TruSeq Rapid Exome kit (Illumina, San Diego, CA, USA). Mitochondrial protein translation was studied following the Sasarman and Shoubridge protocol and oxygen consumption rates with Agilent Seahorse XF24 Analyzer Mi tostress Test, (Agilent, Santa Clara, CA, USA). We report two siblings with two novel compound heterozygous pathogenic variants in YARS2 gene: a single nucleotide deletion in exon 1, c.314delG (p.(Gly105Alafs*4)), which creates a premature stop codon in the amino acid 109, and a single nu cleotide change in exon 5 c.1391T>C (p.(Ile464Thr)), that cause a missense variant in amino acid 464. We demonstrate the pathogenicity of these new variants associated with reduced YARS2 mRNA transcript, reduced mitochondrial protein translation and dysfunctional organelle function. These pathogenic variants are responsible for late onset MLASA, herein accompanied by pancreatic insuf ficiency, observed in both brothers, clinically considered as Pearson's syndrome. Molecular study of YARS2 gene should be considered in patients presenting Pearson's syndrome characteristics and MLASA related phenotypes

Multicentric Standardization of protocols for the diagnosis of human mitochondrial respiratory chain defects

The quantification of mitochondrial respiratory chain (MRC) enzymatic activities is essential for diagnosis of a wide range of mitochondrial diseases, ranging from inherited defects to secondary dysfunctions. MRC lesion is frequently linked to extended cell damage through the generation of proton leak or oxidative stress, threatening organ viability and patient health. However, the intrinsic challenge of a methodological setup and the high variability in measuring MRC enzymatic activities represents a major obstacle for comparative analysis amongst institutions. To improve experimental and statistical robustness, seven Spanish centers with extensive experience in mitochondrial research and diagnosis joined to standardize common protocols for spectrophotometric MRC enzymatic measurements using minimum amounts of sample. Herein, we present the detailed protocols, reference ranges, tips and troubleshooting methods for experimental and analytical setups in different sample preparations and tissues that will allow an international standardization of common protocols for the diagnosis of MRC defects. Methodological standardization is a crucial step to obtain comparable reference ranges and international standards for laboratory assays to set the path for further diagnosis and research in the field of mitochondrial diseases

Endothelin-1 promotes vascular smooth muscle cell migration across the artery wall: a mechanism contributing to vascular remodelling and intimal hyperplasia in giant-cell arteritis

Background: Giant-cell arteritis (GCA) is an inflammatory disease of large/medium-sized arteries, frequently involving the temporal arteries (TA). Inflammation-induced vascular remodelling leads to vaso-occlusive events. Circulating endothelin-1 (ET1) is increased in patients with GCA with ischaemic complications suggesting a role for ET-1 in vascular occlusion beyond its vasoactive function. Objective: To investigate whether ET-1 induces a migratory myofibroblastic phenotype in human TAderived vascular smooth muscle cells (VSMC) leading to intimal hyperplasia and vascular occlusion in GCA. Methods and results: Immunofluorescence/confocal microscopy showed increased ET-1 expression in GCA lesions compared with control arteries. In inflamed arteries, ET-1 was predominantly expressed by infiltrating mononuclear cells whereas ET receptors, particularly ET-1 receptor B (ETB R), were expressed by both mononuclear cells and VSMC. ET-1 increased TA-derived VSMC migration in vitro and α-smooth muscle actin (αSMA) expression and migration from the media to the intima in cultured TA explants. ET-1 promoted VSMC motility by increasing activation of focal adhesion kinase (FAK), a crucial molecule in the turnover of focal adhesions during cell migration. FAK activation resulted in Y397 autophosphorylation creating binding sites for Src kinases and the p85 subunit of PI3kinases which, upon ET-1 exposure, colocalised with FAK at the focal adhesions of migrating VSMC. Accordingly, FAK or PI3K inhibition abrogated ET-1-induced migration in vitro. Consistently, ET-1 receptor A and ETB R antagonists reduced αSMA expression and delayed VSMC outgrowth from cultured GCA-involved artery explants. Conclusions: ET-1 is upregulated in GCA lesions and, by promoting VSMC migration towards the intimal layer, may contribute to intimal hyperplasia and vascular occlusion in GCA

Multicentric Standardization of Protocols for the Diagnosis of Human Mitochondrial Respiratory Chain Defects

The study was conducted according to the guidelines of the Declaration of Helsinki and approved by the Institutional Review Board of each institution: IBC U737 (C0000128), HCL U722 (HCB2017/0808), 12O U723 (CEI:18/487), VH U701 (PR(IR)63/2016) and UPO U729 (C.I. 2768-N-21)The quantification of mitochondrial respiratory chain (MRC) enzymatic activities is essential for diagnosis of a wide range of mitochondrial diseases, ranging from inherited defects to secondary dysfunctions. MRC lesion is frequently linked to extended cell damage through the generation of proton leak or oxidative stress, threatening organ viability and patient health. However, the intrinsic challenge of a methodological setup and the high variability in measuring MRC enzymatic activities represents a major obstacle for comparative analysis amongst institutions. To improve experimental and statistical robustness, seven Spanish centers with extensive experience in mitochondrial research and diagnosis joined to standardize common protocols for spectrophotometric MRC enzymatic measurements using minimum amounts of sample. Herein, we present the detailed protocols, reference ranges, tips and troubleshooting methods for experimental and analytical setups in different sample preparations and tissues that will allow an international standardization of common protocols for the diagnosis of MRC defects. Methodological standardization is a crucial step to obtain comparable reference ranges and international standards for laboratory assays to set the path for further diagnosis and research in the field of mitochondrial diseasesThis work was supported by Instituto de Salud Carlos III (ISCIII), grants FIS PI17/00021, PI17/00359, PI18/00498, PI18/00451, PI18/01374, PI19/01772, PI20/00541, PI21/00229, PI21/00381 and PI21/00935 (ISCIII-FEDER “Cofinanciado por la Unión Europea”), Fundació Privada Cellex, Junta de Andalucía (UPO-1262247) and Ministerio de Ciencia e Innovación (MCINN) grant PID2019-110320RBI00. All participant centers are integrated in the Centro de Investigación Biomédica en Red (CIBER), Sección de Enfermedades Raras (CIBERER, an initiative of ISCIII), which is the founder of this present methodological stud

Extracellular NK histones promote immune cell anti-tumor activity by inducing cell clusters through binding to CD138 receptor.

BACKGROUND: Natural killer (NK) cells are important anti-tumor cells of our innate immune system. Their anti-cancer activity is mediated through interaction of a wide array of activating and inhibitory receptors with their ligands on tumor cells. After activation, NK cells also secrete a variety of pro-inflammatory molecules that contribute to the final immune response by modulating other innate and adaptive immune cells. In this regard, external proteins from NK cell secretome and the mechanisms by which they mediate these responses are poorly defined. METHODS: TRANS-stable-isotope labeling of amino acids in cell culture (TRANS-SILAC) combined with proteomic was undertaken to identify early materials transferred between cord blood-derived NK cells (CB-NK) and multiple myeloma (MM) cells. Further in vitro and in vivo studies with knock-down of histones and CD138, overexpression of histones and addition of exogenous histones were undertaken to confirm TRANS-SILAC results and to determine functional roles of this material transferred. RESULTS: We describe a novel mechanism by which histones are actively released by NK cells early after contact with MM cells. We show that extracellular histones bind to the heparan sulfate proteoglycan CD138 on the surface of MM cells to promote the creation of immune-tumor cell clusters bringing immune and MM cells into close proximity, and thus facilitating not only NK but also T lymphocyte anti-MM activity. CONCLUSION: This study demonstrates a novel immunoregulatory role of NK cells against MM cells mediated by histones, and an additional role of NK cells modulating T lymphocytes activity that will open up new avenues to design future immunotherapy clinical strategies

Mitochondrial Toxicogenomics for Antiretroviral Management: HIV Post-exposure Prophylaxis in Uninfected Patients

Background: Mitochondrial genome has been used across multiple fields in research, diagnosis, and toxicogenomics. Several compounds damage mitochondrial DNA (mtDNA), including biological and therapeutic agents like the human immunodeficiency virus (HIV) but also its antiretroviral treatment, leading to adverse clinical manifestations. HIV-infected and treated patients may show impaired mitochondrial and metabolic profile, but specific contribution of viral or treatment toxicity remains elusive. The evaluation of HIV consequences without treatment interference has been performed in naïve (non-treated) patients, but assessment of treatment toxicity without viral interference is usually restricted to in vitro assays. Objective: The objective of the present study is to determine whether antiretroviral treatment without HIV interference can lead to mtDNA disturbances. We studied clinical, mitochondrial, and metabolic toxicity in non-infected healthy patients who received HIV post-exposure prophylaxis (PEP) to prevent further infection. We assessed two different PEP regimens according to their composition to ascertain if they were the cause of tolerability issues and derived toxicity. Methods: We analyzed reasons for PEP discontinuation and main secondary effects of treatment withdrawal, mtDNA content from peripheral blood mononuclear cells and metabolic profile, before and after 28 days of PEP, in 23 patients classified depending on PEP composition: one protease inhibitor (PI) plus Zidovudine/Lamivudine (PI plus AZT + 3TC; n = 9) or PI plus Tenofovir/Emtricitabine (PI plus TDF + FTC; n = 14). Results: Zidovudine-containing-regimens showed an increased risk for drug discontinuation (RR = 9.33; 95% CI = 1.34-65.23) due to adverse effects of medication related to gastrointestinal complications. In the absence of metabolic disturbances, 4-week PEP containing PI plus AZT + 3TC led to higher mitochondrial toxicity (−17.9 ± 25.8 decrease in mtDNA/nDNA levels) than PI plus TDF + FTC (which increased by 43.2 ± 24.3 units mtDNA/nDNA; p < 0.05 between groups). MtDNA changes showed a significant and negative correlation with baseline alanine transaminase levels (p < 0.05), suggesting that a proper hepatic function may protect from antiretroviral toxicity. Conclusions: In absence of HIV infection, preventive short antiretroviral treatment can cause secondary effects responsible for treatment discontinuation and subclinical mitochondrial damage, especially pyrimidine analogs such as AZT, which still rank as the alternative option and first choice in certain cohorts for PEP. Forthcoming efforts should be focused on launching new strategies with safer clinical and mitotoxic profile

Blocking interferon γ reduces expression of chemokines CXCL9, CXCL10 and CXCL11 and decreases macrophage infiltration in ex vivo cultured arteries from patients with giant cell arteritis

BACKGROUND: Interferon γ (IFNγ) is considered a seminal cytokine in the pathogenesis of giant cell arteritis (GCA), but its functional role has not been investigated. We explored changes in infiltrating cells and biomarkers elicited by blocking IFNγ with a neutralising monoclonal antibody, A6, in temporal arteries from patients with GCA. METHODS: Temporal arteries from 34 patients with GCA (positive histology) and 21 controls were cultured on 3D matrix (Matrigel) and exposed to A6 or recombinant IFNγ. Changes in gene/protein expression were measured by qRT-PCR/western blot or immunoassay. Changes in infiltrating cells were assessed by immunohistochemistry/immunofluorescence. Chemotaxis/adhesion assays were performed with temporal artery-derived vascular smooth muscle cells (VSMCs) and peripheral blood mononuclear cells (PBMCs). RESULTS: Blocking endogenous IFNγ with A6 abrogated STAT-1 phosphorylation in cultured GCA arteries. Furthermore, selective reduction in CXCL9, CXCL10 and CXCL11 chemokine expression was observed along with reduction in infiltrating CD68 macrophages. Adding IFNγ elicited consistent opposite effects. IFNγ induced CXCL9, CXCL10, CXCL11, CCL2 and intracellular adhesion molecule-1 expression by cultured VSMC, resulting in increased PBMC chemotaxis/adhesion. Spontaneous expression of chemokines was higher in VSMC isolated from GCA-involved arteries than in those obtained from controls. Incubation of IFNγ-treated control arteries with PBMC resulted in adhesion/infiltration by CD68 macrophages, which did not occur in untreated arteries. CONCLUSIONS: Our ex vivo system suggests that IFNγ may play an important role in the recruitment of macrophages in GCA by inducing production of specific chemokines and adhesion molecules. Vascular wall components (ie, VSMC) are mediators of these functions and may facilitate progression of inflammatory infiltrates through the vessel wall

Expression and function of IL12/23 related cytokine subunits (p35, p40, and p19) in giant-cell arteritis lesions: contribution of p40 to Th1- and Th17-mediated inflammatory pathways

Background: Giant-cell arteritis (GCA) is considered a T helper (Th)1- and Th17-mediated disease. Interleukin (IL)-12 is a heterodimeric cytokine (p35/p40) involved in Th1 differentiation. When combining with p19 subunit, p40 compose IL-23, a powerful pro-inflammatory cytokine that maintains Th17 response. Objectives: The aims of this study were to investigate p40, p35, and p19 subunit expression in GCA lesions and their combinations to conform different cytokines, to assess the effect of glucocorticoid treatment on subunit expression, and to explore functional roles of p40 by culturing temporal artery sections with a neutralizing anti-human IL-12/IL-23p40 antibody. Methods and results: p40 and p19 mRNA concentrations measured by real-time RT-PCR were significantly higher in temporal arteries from 50 patients compared to 20 controls (4.35 ± 4.06 vs 0.51 ± 0.75; p < 0.0001 and 20.32 ± 21.78 vs 4.17 ± 4.43 relative units; p < 0.0001, respectively). No differences were found in constitutively expressed p35 mRNA. Contrarily, p40 and p19 mRNAs were decreased in temporal arteries from 16 treated GCA patients vs those from 34 treatment-naïve GCA patients. Accordingly, dexamethasone reduced p40 and p19 expression in cultured arteries. Subunit associations to conform IL-12 and IL-23 were confirmed by proximity-ligation assay in GCA lesions. Immunofluorescence revealed widespread p19 and p35 expression by inflammatory cells, independent from p40. Blocking IL-12/IL-23p40 tended to reduce IFNγ and IL-17 mRNA production by cultured GCA arteries and tended to increase Th17 inducers IL-1β and IL-6. Conclusion: IL-12 and IL-23 heterodimers are increased in GCA lesions and decrease with glucocorticoid treatment. p19 and p35 subunits are much more abundant than p40, indicating an independent role for these subunits or their potential association with alternative subunits. The modest effect of IL-12/IL-23p40 neutralization may indicate compensation by redundant cytokines or cytokines resulting from alternative combinations

Ductular reaction promotes intrahepatic angiogenesis through Slit2-Roundabout 1 signaling

Background and aims: Ductular reaction (DR) expands in chronic liver diseases and correlates with disease severity. Besides its potential role in liver regeneration, DR plays a role in the wound-healing response of the liver, promoting periductular fibrosis and inflammatory cell recruitment. However, there is no information regarding its role in intrahepatic angiogenesis. In the current study we investigated the potential contribution of DR cells to hepatic vascular remodeling during chronic liver disease. Approach and results: In mouse models of liver injury, DR cells express genes involved in angiogenesis. Among angiogenesis-related genes, the expression of Slit2 and its receptor Roundabout 1 (Robo1) was localized in DR cells and neoangiogenic vessels, respectively. The angiogenic role of the Slit2-Robo1 pathway in chronic liver disease was confirmed in ROBO1/2-/+ mice treated with 3,5-diethoxycarbonyl-1,4-dihydrocollidine, which displayed reduced intrahepatic neovascular density compared to wild-type mice. However, ROBO1/2 deficiency did not affect angiogenesis in partial hepatectomy. In patients with advanced alcohol-associated disease, angiogenesis was associated with DR, and up-regulation of SLIT2-ROBO1 correlated with DR and disease severity. In vitro, human liver-derived organoids produced SLIT2 and induced tube formation of endothelial cells. Conclusions: Overall, our data indicate that DR expansion promotes angiogenesis through the Slit2-Robo1 pathway and recognize DR cells as key players in the liver wound-healing response.Supported by grants from Fondo de Investigación Sanitaria Carlos III (FIS), cofinanced by Fondo Europeo de Desarrollo Regional (FEDER), Unión Europea, “Una manera de hacer Europa” (FIS PI20/00765, PI17/00673, to P.S.-B; FIS 18-PI18/00862, to I.G and M.C); from the National Institute on Alcohol Abuse and Alcoholism (1U01AA026972-01 and AGAUR 2017-SGR-01456, to P.S.-B.); and from the European Foundation for Alcohol Research (EA1653, to P.S.-B.). M.C. is funded by the Ramon y Cajal program from the Ministerio de Ciencia e Innovación RYC2019-026662-I. P.G. is funded by the Agencia de Gestió d'Ajuts Universitaris i de Recerca 2014 SGR 708, Centro de Investigaciónen Red Enfermedades Hepáticas y Digestivas (CIBERehd), and Institució Catalana de Recerca i Estudis Avançats. S.A. received a grant from the Ministerio de Educación, Cultura y Deporte (FPU17/04992). B.A.-B. is funded by the Instituto de Salud Carlos III (FI16/00203