Attivazione e deplezione selettiva di linfociti antigene-specifici

2010/2011Il trapianto di cellule staminali emopoietiche (TSCE) consiste nell’infusione di cellule staminali di donatore in grado di ripopolare l’intero sistema emopoietico del ricevente. Con il TSCE, però, viene infusa anche una certa quota di linfociti maturi specifici contro vari antigeni. Questi sono capaci di dar origine ad una risposta immune “positiva” o “utile” che può proteggere il ricevente da infezioni e recidive, perché una volta infusi nel ricevente sono capaci di rispondere ai patogeni (Graft versus Infection) o agli antigeni tumorali (Graft versus Tumor). D’altra parte, però, linfociti specifici contro gli antigeni dell’ospite possono dar origine alla reazione di rigetto del “trapianto contro l’ospite” (Graft versus Host Disease, GvHD) in cui i linfociti del donatore riconoscono come non self gli antigeni tessutali del ricevente (alloantigeni). Recentemente diversi gruppi hanno studiato come migliorare l’esito del trapianto, mettendo a punto diversi protocolli per eliminare solo le cellule responsabili di GvHD, ma molto va ancora fatto per ottimizzare queste tecniche e far sì che non vengano persi anche i linfociti patogeno-specifici o regolatori. Questo lavoro ha voluto mettere a punto un metodo di deplezione basato sull’uso di piccole molecole in grado di interferire con il processo di attivazione e proliferazione dei linfociti in risposta allo stimolo allogenico. Per fare questo sono state selezionate diverse molecole: il metotrexate, che interferisce con il metabolismo di sintesi delle basi puriniche; il phenoxodiolo che altera il potenziale di membrana; il tasocitinib che blocca la via di trasduzione del segnale di JAK3; il bortezomib, un inibitore del proteosoma; l’acido 3-idrossiantranilico (3-HAA), che agisce consumando il GSH necessario durante il processo proliferativo e induce l’apoptosi per burst ossidativo, effetto che può essere aumentato dalla presenza di ioni di manganese. Inizialmente i farmaci sono stati testati sia su cellule non stimolate che su cellule attivate con PHA, per identificare il farmaco in grado di esercitare la massima azione tossica sulle cellule attivate ma non su quelle non stimolate. In questa fase, il 3-HAA (con o senza l’aggiunta di ioni manganese) e il bortezomib sono risultati i farmaci dotati di maggiore selettività e potenza. Nella fase successiva, è stata studiata l’azione di questi farmaci su linfociti sottoposti ad uno stimolo allogenico, costituito da linee linfoblastoidi trasformate con virus di Epstein Barr. Infine il 3-HAA in associazione con gli ioni di manganese è stato utilizzato per depletare i linfociti attivati in co-coltura con cellule dendritiche. Dopo la coltura primaria le cellule sono state restimolate con cellule dendritiche dello stesso donatore o di donatore diverso per verificarne la reattività residua. I risultati mostrano che tra i farmaci selezionati inizialmente, il 3-HAA, in associazione con MnCl2 mostra una sufficiente azione tossica selettivamente sulle cellule attivate, risparmiando le cellule non attivate. Il bortezomib che inizialmente aveva dato risultati interessanti, non ha mostrato negli esperimenti successivi un effetto ripetibile. Uno dei problemi emersi, che resta da valutare, è la relativa non-responsività alla restimolazione nelle cellule trattate con i farmaci, forse per la persistenza del farmaco o del suo effetto al loro interno. Il passo successivo sarà mettere a punto le tempistiche ottimali per verificare la reattività residua dopo la deplezione. In generale però, questi risultati mostrano che l’allodeplezione con i farmaci è una strada percorribile, anche se molto va ancora fatto per ottimizzare le tempistiche di somministrazione dei farmaci e sulla valutazione della reattività residua.XXIV Cicl

Knockdown of MVK does not lead to changes in NALP3 expression or activation

Mutations in the Mevalonate Kinase gene (MVK) are causes of a rare autoinflammatory disease: Mevalonate Kinase Deficiency and its more acute manifestation, Mevalonic Aciduria. The latter is characterized, among other features, by neuroinflammation, developmental delay and ataxia, due to failed cerebellar development or neuronal death through chronic inflammation. Pathogenesis of neuroinflammation in Mevalonate Kinase Deficiency and Mevalonic Aciduria has not yet been completely clarified, however different research groups have been suggesting the inflammasome complex as the key factor in the disease development. A strategy to mimic this disease is blocking the mevalonate pathway, using HMG-CoA reductase inhibitors (Statins), while knock-out mice for Mevalonate Kinase are non-vital and their hemyzygous (i.e only one copy of gene preserved) littermate display almost no pathological features

An Easy and Reliable Strategy for Making Type I Interferon Signature Analysis Comparable among Research Centers

Interferon-stimulated genes (ISGs) are a set of genes whose transcription is induced by interferon (IFN). The measure of the expression of ISGs enables calculating an IFN score, which gives an indirect estimate of the exposition of cells to IFN-mediated inflammation. The measure of the IFN score is proposed for the screening of monogenic interferonopathies, like the Aicardi-Gouti\ue8res syndrome, or to stratify subjects with systemic lupus erythematosus to receive IFN-targeted treatments. Apart from these scenarios, there is no agreement on the diagnostic value of the score in distinguishing IFN-related disorders from diseases dominated by other types of cytokines. Since the IFN score is currently measured in several research hospitals, merging experiences could help define the potential of scoring IFN inflammation in clinical practice. However, the IFN score calculated at different laboratories may be hardly comparable due to the distinct sets of IFN-stimulated genes assessed and to different controls used for data normalization. We developed a reliable approach to minimize the inter-laboratory variability, thereby providing shared strategies for the IFN signature analysis and allowing different centers to compare data and merge their experiences

Population pharmacokinetics of intravenous acyclovir in oncologic pediatric patients

Background: Acyclovir represents the first-line prophylaxis and therapy for herpes virus infections. However, its pharmacokinetics in children exposes them to the risk of ineffective or toxic concentrations. The study was aimed at investigating the population pharmacokinetics (POP/PK) of intravenous (IV) acyclovir in oncologic children. Methods: Patients (age, 8.6 ± 5.0 years, 73 males and 47 females) received IV acyclovir for prophylaxis (n = 94) and therapy (n = 26) under a therapeutic drug monitoring (i.e., minimum and maximal plasma concentrations, >0.5 and <25 mg/L, respectively). Plasma concentrations were fitted by nonlinear mixed effect modeling and a simulation of dosing regimens was performed. Findings were stratified according to an estimated glomerular filtration rate (eGFR) threshold of 250 ml/min/1.73m2. Results: The final 1-compartment POP/PK model showed that eGFR had a significant effect on drug clearance, while allometric body weight influenced both clearance and volume of distribution. The population clearance (14.0 ± 5.5 L/h) was consistent across occasions. Simulation of standard 1-h IV infusion showed that a 10-mg/kg dose every 6 h achieved target concentrations in children with normal eGFR (i.e., ≤250 ml/min/1.73m2). Increased eGFR values required higher doses that led to an augmented risk of toxic peak concentrations. On the contrary, simulated prolonged (i.e., 2 and 3-h) or continuous IV infusions at lower doses increased the probability of target attainment while reducing the risk of toxicities. Conclusion: Due to the variable pharmacokinetics of acyclovir, standard dosing regimens may not be effective in some patients. Prospective trials should confirm the therapeutic advantage of prolonged and continuous IV infusion

Altered pattern of tumor necrosis factor-Alpha production in peripheral blood monocytes from Crohn's disease basic study

AIM: To evaluate the inflammatory state in Crohn's disease (CD) patients and correlate it with genetic background and microbial spreading. METHODS: By means of flow cytometry, production of tumor necrosis factor-alpha (TNF-\u3b1) was measured in peripheral blood monocytes from patients suffering from CD, ulcerative colitis (UC) and in healthy subjects after stimulation of the NOD2 and TLR pathways. CD patients were genotyped for the three most common NOD2 variants (R702W, G908R and L1007Pfs*2) and basal production of TNF-\u3b1 was correlated to NOD2 genotype. Also, production of TNF-\u3b1 was correlated to plasmatic levels of LPS Binding Protein (LBP), soluble (s) CD14 and to the activity state of the disease. RESULTS: The patients with CD were characterized by a significantly higher monocyte basal expression of TNF-\u3b1 compared with healthy subjects and UC patients, and after stimulation with Pam3CSK4 (ligand of TLR2/1) and MDP-L18 (ligand of NOD2) this difference was maintained, while other microbial stimuli (LPS, ligand of TLR4 and PolyI:C, ligand of TLR3) induced massive activation in CD monocytes as well as in UC and in healthy control cells. There was no significant difference in the production of TNF-\u3b1 between patients who carried CD-associated heterozygous or homozygous variants in NOD2 and patients with wild type NOD2 genotype. Although serum LBP levels have been shown to correlate positively with the state of activity of the disease, TNF-\u3b1 production did not show a clear correlation with either LBP or sCD14 levels in plasma. Moreover, no clear correlation was seen between TNF-\u3b1 production and activity indices in either CD or UC. CONCLUSION: Peripheral monocytes from CD express higher basal and stimulated TNF-\u3b1 than controls, regardless of NOD2 genotype and without a clear correlation with disease activity

Reappraisal of Antimalarials in Interferonopathies: New Perspectives for Old Drugs

The story of antimalarials as antinflammatory drugs dates back several centuries. Chinin, the extract of the Cinchona bark, has been exploited since the 18th century for its antimalarial and antifebrile properties. Later, during the Second World War, the broad use of antimalarials allowed arguing their antirheumatic effect on soldiers. Since then, these drugs have been broadly used to treat Systemic Lupus Erythematosus, but, only recently, have the molecular mechanisms of action been partly clarified. Inhibitory action on vacuole function and trafficking has been considered for decades the main mechanism of the action of antimalarials, affecting the activation of phagocytes and dendritic cells. In addition, chloroquine is also known as a potent inhibitor of autophagy, providing another possible explanation of its antinflammatory action. However, much attention has been recently devoted to the action of antimalarials on the so-called cGAS-STING pathway leading from the sensing of cytoplasmic nucleic acids to the production of type I interferons. This pathway is a fundamental mechanism of host defence, since it is able to detect microbial DNA and induce the type I interferon-mediated immune response. Of note, genetic defects in the degradation of nucleic acids lead to inappropriate cGAS-STING activation and inflammation. These disorders, called type I interferonopathies, represent a valuable model to study the antinflammatory potential of antimalarials. We will discuss possible development of antimalarials to improve the treatment of type I interferonopathies and likely multifactorial disorders characterised by interferon inflammation, such as Systemic Lupus Erythematosus

Long Noncoding RNA GAS5: A Novel Marker Involved in Glucocorticoid Response

Glucocorticoids (GCs) exert their effects through regulation of gene expression after activation in the cytoplasm of the glucocorticoid receptor (GR) encoded by NR3C1 gene. A negative feedback mechanism resulting in GR autoregulation has been demonstrated through the binding of the activated receptor to intragenic sequences called GRE-like elements, contained in GR gene. The long noncoding RNA growth arrest-specific transcript 5 (GAS5) interacts with the activated GR suppressing its transcriptional activity. The aim of this study was to evaluate the possible role of GAS5 and NR3C1 gene expression in the antiproliferative effect of methylprednisolone in peripheral blood mononuclear cells and to correlate the expression with individual sensitivity to GCs. Subjects being poor responders to GCs presented higher levels of GAS5 and NR3C1 in comparison with good responders. We suggest that abnormal levels of GAS5 may alter GC effectiveness, probably interfering with the mechanism of GR autoregulation

Impact of methylmercury and other heavy metals exposure on neurocognitive function in children of 7 years old: study protocol of the follow-up

BACKGROUND: The extent to which prenatal low-level mercury (Hg) exposure through maternal fish intake and heavy metals exposure affect children neurodevelopment is controversial and may appear in long term. In 2007 a prospective cohort, the Northern Adriatic Cohort II (NAC-II), was established to investigate the association between prenatal Hg exposure from maternal fish consumption and child neurodevelopment. 900 pregnant women were enrolled. 632 and 470 children underwent neurodevelopmental evaluation, respectively, at 18 and 40 months of age. The NAC-II cohort is a part of the Mediterranean cohort in "Public health impact of long-term, low-level, mixed element exposure in susceptible population strata" project.METHODS: This protocol describes the follow-up assessment of the effects of prenatal low level Hg and other heavy metals exposure on the developing nervous system of the children born within the NAC-II and reached the age of 7 years. Child diet components are estimated through a Diet Diary. Child hair and urine are collected for determination of Hg level. In addition, levels of other potentially neurotoxic metals, namely Manganese, Cadmium, Lead, Arsenic and Selenium are also measured in the same matrices.DiscussionThis protocol extends to the first years of schooling age the evaluation of the neurotoxicant effect of Mercury and of the other heavy metals on children's neurodevelopment, adjusting for the potential confounders such as the lifestyles and the social economic status of children's families. Longitudinal analysis of neurodevelopment, assessed in different ages (18, 40 months and 7 years), are performed

Neuronal dysfunction associated with cholesterol deregulation

Cholesterol metabolism is crucial for cells and, in particular, its biosynthesis in the central nervous system occurs in situ, and its deregulation involves morphological changes that cause functional variations and trigger programmed cell death. The pathogenesis of rare diseases, such as Mevalonate Kinase Deficiency or Smith–Lemli–Opitz Syndrome, arises due to enzymatic defects in the cholesterol metabolic pathways, resulting in a shortage of downstream products. The most severe clinical manifestations of these diseases appear as neurological defects. Expanding the knowledge of this biological mechanism will be useful for identifying potential targets and preventing neuronal damage. Several studies have demonstrated that deregulation of the cholesterol pathway induces mitochondrial dysfunction as the result of respiratory chain damage. We set out to determine whether mitochondrial damage may be prevented by using protective mitochondria-targeted compounds, such as MitoQ, in a neuronal cell line treated with a statin to induce a biochemical block of the cholesterol pathway. Evidence from the literature suggests that mitochondria play a crucial role in the apoptotic mechanism secondary to blocking the cholesterol pathway. Our study shows that MitoQ, administered as a preventive agent, could counteract the cell damage induced by statins in the early stages, but its protective role fades over time

Type I interferon-mediated autoinflammation due to DNase II deficiency

Microbial nucleic acid recognition serves as the major stimulus to an antiviral response, implying a requirement to limit the misrepresentation of self nucleic acids as non-self and the induction of autoinflammation. By systematic screening using a panel of interferon-stimulated genes we identify two siblings and a singleton variably demonstrating severe neonatal anemia, membranoproliferative glomerulonephritis, liver fibrosis, deforming arthropathy and increased anti-DNA antibodies. In both families we identify biallelic mutations in DNASE2, associated with a loss of DNase II endonuclease activity. We record increased interferon alpha protein levels using digital ELISA, enhanced interferon signaling by RNA-Seq analysis and constitutive upregulation of phosphorylated STAT1 and STAT3 in patient lymphocytes and monocytes. A hematological disease transcriptomic signature and increased numbers of erythroblasts are recorded in patient peripheral blood, suggesting that interferon might have a particular effect on hematopoiesis. These data define a type I interferonopathy due to DNase II deficiency in humans