Therapeutic alternatives in chronic thromboembolic pulmonary hypertension: from pulmonary endarterectomy to balloon pulmonary angioplasty to medical therapy. State of the art from a multidisciplinary team.

Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare disease with a very complex pathophysiology differing from other causes of pulmonary hypertension (PH). It is an infrequent consequence of acute pulmonary embolism that is frequently misdiagnosed. Pathogenesis has been related to coagulation abnormalities, infection or inflammation, although these disturbances can be absent in many cases. The hallmarks of CTEPH are thrombotic occlusion of pulmonary vessels, variable degree of ventricular dysfunction and secondary microvascular arteriopathy. The definition of CTEPH also includes an increase in mean pulmonary arterial pressure of more than 25 mmHg with a normal pulmonary capillary wedge of less than 15 mmHg. It is classified as World Health Organization group 4 PH, and is the only type that can be surgically cured by pulmonary endarterectomy (PEA). This operation needs to be carried out by a team with strong expertise, from the diagnostic and decisional pathway to the operation itself. However, because the disease has a very heterogeneous phenotype in terms of anatomy, degree of PH and the lack of a standard patient profile, not all cases of CTEPH can be treated by PEA. As a result, PH-directed medical therapy traditionally used for the other types of PH has been proposed and is utilized in CTEPH patients. Since 2015, we have been witnessing the rebirth of balloon pulmonary angioplasty, a technique first performed in 2001 but has since fallen out fashion due to major complications. The refinement of such techniques has allowed its safe utilization as a salvage therapy in inoperable patients. In the present keynote lecture, we will describe these therapeutic approaches and results.

Impact of Predicted Heart Mass-Based Donor-Recipient Size Matching on Transplant Outcomes.

BACKGROUND: Currently, guidelines for appropriate donor sizing in recipients mostly focuses on donor-recipient body weight matching. The purpose is to retrospectively determine the impact of predicted heart mass (pHM)-based size matching on heart transplant (HT) outcomes. METHODS: According to our institutional registry, 512 consecutive adult patients underwent HT between January 2000 and August 2020. For each patient, pHM and donor-recipient pHM ratio were calculated. Patients were partitioned into quintiles in terms of pHM ratio: undersizing 2, undersizing 1, reference, oversizing 1, and oversizing 2, with mean pHM donor-recipient ratio of 0.81, 0.96, 1.04, 1.12, and 1.28, respectively. Severe early graft failure and 30-day, 90-day, 1-year, and 10-year mortality were analyzed as outcomes. RESULTS: Recipients of the most oversized group were mostly female (P < .001), had higher preoperative pulmonary vascular resistance (P = .009), had higher rate of mechanical circulatory support (P < .05), and showed a lower United Network for Organ Sharing score (P = .041); the respective donors were younger and more frequently male (P = .001). Ischemic time was similar in all groups (P = .358). Pulmonary vascular resistance (P = .023; odds ratio [OR], 2.38), preoperative mechanical circulatory support (P = .05; OR, 3.06), and United Network for Organ Sharing score (P = .033; OR, 1.76) were identified as risk factors for early mortality. Donor-recipient pHM ratio did not impact early graft failure (P = .871) and early mortality (P = .526). Survival analysis after adjustment for pHM ratio subgroups did not show any difference in outcomes. CONCLUSIONS: A wide range of pHM ratios seems to be safe. A careful allocation of organs, by considering a pHM ratio mismatch, may balance rescue preoperative clinical profiles and preserve HT outcomes.

Deficient production of IL-1 receptor antagonist and IL-6 coupled to oxidative stress in cryopyrin-associated periodic syndrome monocytes.

OBJECTIVE: To determine whether dysregulated production of cytokines downstream of interleukin (IL)-1 participates in the pathophysiology of cryopyrin-associated periodic syndromes (CAPS). METHODS: Primary monocytes from patients with CAPS, unstimulated or after stimulation with lipopolysaccharide (LPS) and other Toll-like receptor (TLR) agonists, were examined for signs of stress and production of IL-1ß, IL-1 receptor antagonist (IL-1Ra) and IL-6 in comparison with monocytes from patients with autoimmune diseases and from healthy donors. RESULTS: Unstimulated CAPS monocytes showed mild signs of stress including elevated levels of reactive oxygen species and fragmented mitochondria. Stress signs were worsened by TLR stimulation and eventually led to protein synthesis inhibition with strong impairment of production of cytokines downstream of IL-1, such as IL-1Ra and IL-6. These defects were not detected in monocytes from autoimmune patients and healthy donors. CONCLUSIONS: The stress state of LPS-stimulated CAPS monocytes and the consequent inhibition of translation are likely to be responsible for the impaired production of IL-1Ra and IL-6. The deficient secretion of these cytokines coupled with increased IL-1ß release explains the severity of the IL-1-related clinical manifestations and the predominant implication of innate immunity in CAPS.

The rate of interleukin-1beta secretion in different myeloid cells varies with the extent of redox response to Toll-like receptor triggering.

Human myeloid cells activate the NLRP3 inflammasome and secrete interleukin (IL)-1ß in response to various Toll-like receptor (TLR) ligands, but the rate of secretion is much higher in primary human monocytes than in cultured macrophages or THP-1 cells. The different myeloid cells also display different redox status under resting conditions and redox response to TLR activation. Resting monocytes display a balanced redox state, with low production of reactive oxygen species (ROS) and antioxidants. TLR engagement induces an effective redox response with increased ROS generation followed by a sustained antioxidant response, parallelled by efficient IL-1ß secretion. Drugs blocking ROS production or the antioxidant response prevent the secretion of mature IL-1ß but not the biosynthesis of pro-IL-1ß, indicating that redox remodeling is responsible for IL-1ß processing and release. Unlike monocytes, THP-1 cells and cultured macrophages have up-regulated antioxidant systems that buffer the oxidative hit provided by TLR triggering and suppress the consequent redox response. This aborted redox remodeling is paralleled by low efficiency IL-1ß processing and secretion. High doses (5 mM) of H(2)O(2) overcome the high antioxidant capacity of THP-1 cells, restore an efficient redox response, and increase the rate of IL-1ß secretion. Together these data indicate that a tightly controlled redox homeostasis in resting cells is a prerequisite for a robust redox response to TLR ligands, in turn necessary for the efficient inflammasome activation. Inflammasome activation by bacterial DNA is not modulated by redox responses, suggesting that redox-dependent regulation of IL-1ß secretion is restricted to some inflammasomes including NLRP3 but excluding AIM-2.

Altered redox state of monocytes from cryopyrin-associated periodic syndromes causes accelerated IL-1beta secretion.

In healthy monocytes, Toll-like receptor (TLR) engagement induces production of reactive oxygen species (ROS), followed by an antioxidant response involved in IL-1beta processing and secretion. Markers of the antioxidant response include intracellular thioredoxin and extracellular release of reduced cysteine. Cryopyrin-associated periodic syndromes (CAPS) are autoinflammatory diseases in which Nod-like receptor family pyrin domain-containing 3 (NLRP3) gene mutations lead to increased IL-1beta secretion. We show in a large cohort of patients that IL-1beta secretion by CAPS monocytes is much faster than that by healthy monocytes. This accelerated kinetics is caused by alterations in the basal redox state, as well as in the redox response to TLR triggering displayed by CAPS monocytes. Indeed, unstimulated CAPS monocytes are under a mild oxidative stress, with elevated levels of both ROS and antioxidants. The redox response to LPS is quickened, with early generation of the reducing conditions favoring IL-1beta processing and secretion, and then rapidly exhausted. Therefore, secretion of IL-1beta is accelerated, but reaches a plateau much earlier than in healthy controls. Pharmacologic inhibition of the redox response hinders IL-1beta release, confirming the functional link between redox impairment and altered kinetics of secretion. Monocytes from patients with juvenile idiopathic arthritis display normal kinetics of redox response and IL-1beta secretion, excluding a role of chronic inflammation in the alterations observed in CAPS. We conclude that preexisting redox alterations distinct from CAPS monocytes anticipate the pathogen-associated molecular pattern molecule-induced generation of the reducing environment favorable to inflammasome activation and IL-1beta secretion.

DAMPs and inflammatory processes: the role of redox in the different outcomes.

Inflammation is deeply entangled with redox modulation. Triggering of PRRs on inflammatory cells induces ROS generation. As a consequence, activated cells mount antioxidant responses to counteract the possible harmful effects of oxidation. Therefore, when repair is completed, homeostasis is restored. Here, we describe some recent results showing that an exuberant antioxidant response to pro-oxidant inflammatory stimuli modifies not only the intra- but also the extracellular redox and contributes to the outcome of the inflammatory process. In particular, the role of redox modulation in IL-1beta secretion, in B lymphocyte differentiation to plasma cells, and in tumor progression will be discussed, and the potential consequences of extracellular redox alterations on DAMP activity will be considered.

Pathogen-induced interleukin-1beta processing and secretion is regulated by a biphasic redox response.

In this study, we show that IL-1beta processing and secretion induced by pathogen-associated molecular pattern (PAMP) molecules in human monocytes is regulated by a biphasic redox event including a prompt oxidative stress and a delayed antioxidant response. Namely, PAMPs induce an early generation of reactive oxygen species (ROS) followed by increase of intracellular thioredoxin and release of reduced cysteine: this antioxidant phase is paralleled by secretion of mature IL-1beta. ROS production and antioxidant response are both required, because either inhibitors of NADPH oxidase and of thioredoxin reductase impair IL-1beta secretion. These inhibitors also hinder cysteine release and consequently prevent reduction of the extracellular medium: addition of exogenous reducing agents restores IL-1beta secretion. Not only silencing of thioredoxin, but also of the ROS scavenger superoxide dismutase 1 results in inhibition of IL-1beta secretion. Thus, PAMP-induced ROS trigger an antioxidant response involving intracellular redox enzymes and release of cysteine, ultimately required for IL-1beta processing and secretion.

ATP is released by monocytes stimulated with pathogen-sensing receptor ligands and induces IL-1beta and IL-18 secretion in an autocrine way.

IL-1beta and IL-18 are crucial mediators of inflammation, and a defective control of their release may cause serious diseases. Yet, the mechanisms regulating IL-1beta and IL-18 secretion are partially undefined. Both cytokines are produced as inactive cytoplasmic precursors. Processing to the active form is mediated by caspase-1, which is in turn activated by the multiprotein complex inflammasome. Here, we show that in primary human monocytes microbial components acting on different pathogen-sensing receptors and the danger-associated molecule uric acid are all competent to induce maturation and secretion of IL-1beta and IL-18 through a process that involves as a first event the extracellular release of endogenous ATP. ATP release is followed by autocrine stimulation of the purinergic receptors P2X(7). Indeed, antagonists of the P2X(7) receptor (P2X(7)R), or treatment with apyrase, prevent IL-1beta and IL-18 maturation and secretion triggered by the different stimuli. At variance, blocking P2X(7)R activity has no effects on IL-1beta secretion by monocytes carrying a mutated inflammasome that does not require exogenous ATP for activation. P2X(7)R engagement is followed by K+ efflux and activation of phospholipase A(2). Both events are required for processing and secretion induced by all of the stimuli. Thus, stimuli acting on different pathogen-sensing receptors converge on a common pathway where ATP externalization is the first step in the cascade of events leading to inflammasome activation and IL-1beta and IL-18 secretion.

The pattern of response to anti-interleukin-1 treatment distinguishes two subsets of patients with systemic-onset juvenile idiopathic arthritis.

OBJECTIVE: To assess the clinical response to interleukin-1 (IL-1) blockade and in vitro IL-1beta and IL-18 secretion in patients with systemic-onset juvenile idiopathic arthritis (JIA). METHODS: Twenty-two patients with systemic-onset JIA were treated with the IL-1 receptor antagonist (IL-1Ra) anakinra. Monocytes from 18 patients and 20 healthy donors were activated by different Toll-like receptor ligands. Intracellular and secreted IL-1beta and IL-18 were analyzed by Western blotting and enzyme-linked immunosorbent assay. RESULTS: Ten patients with systemic-onset JIA exhibited a dramatic response to anakinra and were classified as complete responders. Eleven patients had an incomplete response or no response, and 1 patient could not be classified in terms of response. Compared with patients who had an incomplete response or no response, complete responders had a lower number of active joints (P = 0.02) and an increased absolute neutrophil count (P = 0.02). In vitro IL-1beta and IL-18 secretion in response to various stimuli was not increased and was independent of treatment efficacy. Likewise, secretion of IL-1Ra by monocytes from patients with systemic-onset JIA was not impaired. An overall low level of IL-1beta secretion upon exposure to exogenous ATP was observed, unrelated to treatment responsiveness or disease activity. CONCLUSION: Two subsets of systemic-onset JIA can be identified according to patient response to IL-1 blockade. The 2 subsets appear to be characterized by some distinct clinical features. In vitro secretion of IL-1beta and IL-18 by monocytes from patients with systemic-onset JIA is not increased and is independent of both treatment outcome and disease activity.

Pattern of interleukin-1beta secretion in response to lipopolysaccharide and ATP before and after interleukin-1 blockade in patients with CIAS1 mutations.

OBJECTIVE: To examine the synthesis, processing, and secretion of interleukin-1beta (IL-1beta), as well as the clinical and biologic effects of IL-1 blockade, in patients with chronic infantile neurologic, cutaneous, articular (CINCA) syndrome and Muckle-Wells syndrome (MWS), in an effort to understand the molecular mechanisms linking mutations of the CIAS1 gene and IL-1beta hypersecretion, and the underlying response to IL-1 receptor antagonist (IL-1Ra). METHODS: Six patients with CINCA syndrome or MWS were treated with IL-1Ra and followed up longitudinally. Monocytes obtained from the patients and from 24 healthy donors were activated with lipopolysaccharide (LPS) for 3 hours, and intracellular and secreted IL-1beta levels were determined by Western blotting and enzyme-linked immunosorbent assay before and after exposure to exogenous ATP. RESULTS: LPS-induced IL-1beta secretion was markedly increased in monocytes from patients with CIAS1 mutations. However, unlike in healthy subjects, secretion of IL-1beta was not induced by exogenous ATP. Treatment with IL-1Ra resulted in a dramatic clinical improvement, which was paralleled by an early and strong down-regulation of LPS-induced IL-1beta secretion by the patients' cells in vitro. CONCLUSION: Our results showed that the requirements of ATP stimulation for IL-1beta release observed in healthy individuals are bypassed in patients bearing CIAS1 mutations. This indicates that cryopyrin is the direct target of ATP and that the mutations release the protein from the requirement of ATP for activation. In addition, the dramatic amelioration induced by IL-1Ra treatment is at least partly due to the strong decrease in IL-1beta secretion that follows the first injections of the antagonist. These findings may have implications for other chronic inflammatory conditions characterized by increased IL-1beta.

Histone deacetylase inhibitors prevent exocytosis of interleukin-1beta-containing secretory lysosomes: role of microtubules.

A number of agents reducing interleukin-1beta (IL-1beta) activity are being developed as novel immunomodulatory and anti-inflammatory therapies. However, the elucidation of their molecular mechanism of action is required in the context of medical management of inflammatory diseases. Inhibitors of histone deacetylases (HDACs) are promising anticancer agents with pleiotropic activities. Of these, suberoylanilide hydroxamic acid has been reported to inhibit the production of several proinflammatory cytokines. In the present study, we investigated the effects of 2 HDAC inhibitors on IL-1beta secretion: suberoylanilide hydroxamic acid and a newly developed hydroxamic acid-derived compound ITF2357. These HDAC inhibitors do not affect the synthesis or intracellular localization of IL-1beta but both strongly reduce the levels of extracellular IL-1beta by preventing the exocytosis of IL-1beta-containing secretory lysosomes. At nanomolar concentrations, ITF2357 reduces the secretion of IL-1beta following ATP activation of the P2X7 receptor. Whereas the inhibition of HDACs results in hyperacetylation of tubulin, acetylation of HSP90 was unaffected. The reduction in IL-1beta secretion appears to be due to disruption of microtubules impairing lysosome exocytosis. Together, these observations indicate that a functional microtubule network is required for IL-1beta secretion and suggest that disruption of tubulin is the mechanism by which inhibitors of HDACs reduce the secretion of IL-1beta.

ABCA2 is a marker of neural progenitors and neuronal subsets in the adult rodent brain.

The notion that the ATP-binding cassette transporter-A2 (ABCA2) may be involved in brain sterol homeostasis and is associated with early onset Alzheimer's disease led us to explore its neural expression. Our data support and extend the previous reports on ABCA2 expression by oligodendrocytes. They evidence that ABCA2 (i) is located in intracellular vesicles, identified in transfected cells as lysosome-related organelles only partially overlapping with classical endolysosomes; (ii) is a marker of neural progenitors as it is expressed in the subventricular zone of the lateral ventricle and the dentate gyrus of the hippocampal formation, sites of continual neurogenesis in the adult brain, and in nestin(+) cells differentiated in vitro from embryonic stem cells; (iii) persists, in the adult rodent brain, in a subset of GABAergic and glutamatergic neurons. Considering that the latter are targets of Alzheimer's lesions, these data provide a new rationale to explore the neuropathological consequences of ABCA2 functional dysregulations.