Inhibition of nicotinamide phosphoribosyltransferase: cellular bioenergetics reveals a mitochondrial insensitive NAD pool

The NAD rescue pathway consists of two enzymatic steps operated by nicotinamide phosphoribosyltransferase (Nampt) and nicotinamide mononucleotide adenylyltransferases. Recently, the potent Nampt inhibitor FK866 has been identified and evaluated in clinical trials against cancer. Yet, how Nampt inhibition affects NAD contents and bioenergetics is in part obscure. It is also unknown whether NAD rescue takes place in mitochondria, and FK866 alters NAD homeostasis within the organelle. Here, we show that FK866-dependent reduction of the NAD contents is paralleled by a concomitant increase of ATP in various cell types, in keeping with ATP utilization for NAD resynthesis. We also show that poly- and mono(ADP-ribose) transferases rather than Sirt-1 are responsible for NAD depletion in HeLa cells exposed to FK866. Mass spectrometry reveals that the drug distributes in the cytosolic and mitochondrial compartment. However, the cytoplasmic but not the mitochondrial NAD pool is reduced upon acute or chronic exposure to the drug. Accordingly, Nampt does not localize within the organelles and their bioenergetics is not affected by the drug. In the mouse, FK866-dependent reduction of NAD contents in various organs is prevented by inhibitors of poly(ADP-ribose) polymerases or the NAD precursor kynurenine. For the first time, our data indicate that mitochondria lack the canonical NAD rescue pathway, broadening current understanding of cellular bioenergetics.

Pharmacological effects of exogenous NAD on mitochondrial bioenergetics, DNA repair, and apoptosis

During the last several years, evidence that various enzymes hydrolyze NAD into bioactive products prompted scientists to revisit or design strategies able to increase intracellular availability of the dinucleotide. However, plasma membrane permeability to NAD and the mitochondrial origin of the dinucleotide still wait to be clearly defined. Here, we report that intracellular NAD contents increased upon exposure of cell lines or primary cultures to exogenous NAD (eNAD). NAD precursors could not reproduce the effects of eNAD, and they were not found in the incubating medium containing eNAD, thereby suggesting direct cellular eNAD uptake. We found that in mitochondria of cells exposed to eNAD, NAD and NADH as well as oxygen consumption and ATP production were increased. Conversely, DNA repair, a well known NAD-dependent process, was unaltered upon eNAD exposure. We also report that eNAD conferred significant cytoprotection from apoptosis triggered by staurosporine, C2-ceramide, or N-methyl-N'-nitro-N-nitrosoguanidine. In particular, eNAD reduced staurosporine-induced loss of mitochondrial membrane potential and ensuing caspase activation. Of importance, pharmacological inhibition or silencing of the NAD-dependent enzyme SIRT1 abrogated the ability of eNAD to provide protection from staurosporine, having no effect on eNAD-dependent protection from C2-ceramide or N-methyl-N'-nitro-N-nitrosoguanidine. Taken together, our findings, on the one hand, strengthen the hypothesis that eNAD crosses the plasma membrane intact and, on the other hand, provide evidence that increased NAD contents significantly affects mitochondrial bioenergetics and sensitivity to apoptosis.

Poly(ADP-ribose) polymerase-1 is a nuclear epigenetic regulator of mitochondrial DNA repair and transcription

Poly(ADP-ribose) polymerase-1 (PARP-1) is a NAD-consuming enzyme with an emerging key role in epigenetic regulation of gene transcription. Although PARP-1 expression is characteristically restricted to the nucleus, a few studies report the mitochondrial localization of the enzyme and its ability to regulate organelle functioning. Here, we show that, despite exclusive nuclear localization of PARP-1, mitochondrial homeostasis is compromised in cell lines exposed to PARP-1 pharmacological inhibitors or small interfering RNA. PARP-1 suppression reduces integrity of mitochondrial DNA (mtDNA), as well as expression of mitochondria-encoded respiratory complex subunits COX-1, COX-2, and ND-2. Accordingly, PARP-1 localizes at promoters of nuclear genes encoding both the mtDNA repair proteins UNG1, MYH1, and APE1 and the mtDNA transcription factors TFB1M and TFB2M. It is noteworthy that poly(ADP-ribosyl)ation is required for nuclear gene expression of these mitochondrial proteins. Consistent with these findings, PARP-1 suppression impairs mitochondrial ATP production. Our results indicate that PARP-1 plays a central role in mitochondrial homeostasis by epigenetically regulating nuclear genes involved in mtDNA repair and transcription. These data might have important implications in pharmacology of PARP-1 inhibitors as well as clinical oncology and aging.

Ultrasound-guided aspiration of endometriomas: possible applications and limitations

OBJECTIVES

To evaluate the role of needle aspiration in the management of endometriomas.

DESIGN

Retrospective evaluation of the activity of the section of interventional ultrasound in a single tertiary care institution.

SETTING

Department of Obstetrics and Gynecology, Ospedale S. Gerardo, Monza, University of Milan, Italy.

PATIENTS

Two hundred nine premenopausal patients underwent aspiration for diagnostic purpose (n = 166), for relief of symptoms (n = 25), or with therapeutic intent (n = 18).

RESULTS

Adequate material was obtained by all punctures. Early complications (self-limiting vagal symptoms or pain) occurred in eight cases. Short-term complications consisted of acute abdominal pain in three cases and infection in one. Three women required surgical treatment of the complication. At first examination after aspiration, persistence of the cyst was observed in all but four cases, including all cases who had undergone therapeutic aspiration. Nine patients reported relief of symptoms but six other patients referred onset or worsening of pelvic discomfort after aspiration.

CONCLUSIONS

Ultrasound-guided aspiration of endometriomas is feasible. The transvaginal route reduces early complication but implies a risk of infection of 1.3%. However, drainage alone is ineffective as a therapeutic procedure and the applications of aspiration of endometriomas appear limited to some cases with diagnostic intent.

Early and short-term complications after US-guided puncture of gynecologic lesions: evaluation after 1,000 consecutive cases

PURPOSE

To ascertain the complication rate associated with ultrasound (US)-guided puncture of gynecologic lesions.

MATERIALS AND METHODS

Between 1986 and 1992, 878 transabdominal and 122 transvaginal US-guided punctures of gynecologic lesions were performed in 893 patients. Most of the procedures were performed in adnexal cysts (n = 838); the rest, in solid tumors (n = 66), mixed tumors (n = 56), or lymphoceles, abscesses, or fluid collections (n = 40). No anesthesia or antibiotic prophylaxis was routinely used.

RESULTS

No life-threatening complication was recorded. Early complications (defined as complications that occurred within 24 hours after puncture) were recorded in 31 patients and consisted mainly of transient vagal symptoms or pain. Short-term complications (within 5 days after puncture) were recorded in 10 patients, six of whom required surgery.

CONCLUSION

US-guided puncture of gynecologic lesions is safe in selected patients. Complication rates depend on the type of lesion and are very high in dermoid cysts, which should not be punctured, and extremely low in serous cysts, solid tumors, and mixed tumors.

Impact of drug administration route on drug delivery and distribution into the lung: an imaging mass spectrometry approach

During the last decade, significant technological improvements in mass spectrometry have had a great impact on drug discovery. The development of matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI-IMS) has set a new frontier for the study of the distribution of endogenous and exogenous molecules present within a tissue. MALDI-IMS is a surface sampling technique that allows not only the detection of multiple analytes but also gives the spatial distribution of those analytes. Active compounds for pulmonary disease need an optimal and well-studied delivery into the lungs, in order to assure distribution with greater penetration into the peripheral or the alveolar region of the lung to maximize the therapeutic effects. IMS is very useful in the field of drug discovery, showing drug delivery and distribution in the body and organs. In this study, we present a comparison between two different ways of carrying out pulmonary drug administration: inhalation of a nebulized aerosol of aqueous drug solutions and intratracheal administration, which is much simpler, not expensive and commonly used during in vivo screening. Tiotropium bromide is a long-acting anticholinergic medicine used for maintenance treatment of chronic obstructive pulmonary disease. In the present work, tiotropium was administered by nebulization and by intratracheal instillation to guinea pigs at doses able to induce significant anti-bronchoconstrictive activity. Lung samples were dissected, frozen, cryosectioned and coated with matrix (α-hydroxy-cinnamic acid). IMS analyses were performed using a MALDI-LTQ-Orbitrap XL. Using this technique we were able to compare different distributions of the drug depending on the method of administration.

Transvaginal ultrasound-guided fine needle sampling of deep cancer recurrences in the pelvis: usefulness and limitations

The usefulness of fine needle sampling (FNS) under transvaginal ultrasound guidance in gynecologic oncology patients is evaluated in this study. Between 1990 and 1993, 101 FNS under transvaginal ultrasound guidance were performed in 88 sessions. All targets were located deep in the pelvis and their median diameter was 30 mm. All procedures were performed on an outpatient basis. Sampling consisted of 46 cytologic aspirates and 55 biopsies. No false-positive result was obtained when cytologic results were correlated with both clinical outcome and surgical biopsy. For aspirates and biopsies, sensitivity was respectively 76 and 91%, while accuracy was 83 and 91%. Inadequate results were recorded in 11 aspirates and in 9 biopsies. In 7 of 12 sessions where both aspiration and biopsy were performed, false-negative or inadequate cytologic result was overcome by true-positive biopsies. No moderate or severe complication was observed. FNS under transvaginal ultrasound guidance is a safe procedure with limited invasiveness and extremely high specificity even when performed on small targets. Whenever possible, biopsies should be preferred. A negative FNS obtained from a clinically suspicious lesion requires a repeat sampling.

Nicotinamide phosphoribosyltransferase (NAMPT) activity is essential for survival of resting lymphocytes

NAD biosynthesis is emerging as a key regulator of immune cell functions. Accordingly, inhibitors of the NAD-synthesizing enzyme nicotinamide phosphoribosyltransferase (NAMPT) have anti-inflammatory effects, counteract hematological malignancies and are being tested in clinical trials. Still, their effect on different cell types still waits to be fully investigated. Here we show that the NAMPT inhibitor FK866 induces NAD depletion in various mouse organs but selectively causes dramatic atrophy of the spleen red pulp. Accordingly, in cultured mouse lymphocytes exposed to FK866, NAD contents drop to 50% of basal values within 2 days, a condition sufficient to prompt complete cell death. Cultures of human lymphocytes are more resistant to FK866 and sustain a 50% NAD reduction for 5 days before dying. Death of both cell types can be prevented by different NAD precursors, indicating critical NAD homeostasis in lymphocytes. Indeed, inhibition of the NAD-consuming enzyme poly(ADP-ribose) polimerase-1 suffices to prevent FK866-induced NAD depletion and death of both lymphocyte types. Poly(ADP-ribose) polymerase-1-null lymphocytes also undergo lower NAD depletion and reduced cell death when exposed to the drug. At variance with other cell types, neither apoptosis nor autophagy are exclusively responsible for lymphocyte death by FK866, consistent with a general impairment of lymphocyte homeostasis following NAD depletion. Data demonstrate a unique sensitivity of resting lymphocytes to NAD-depleting agents, providing new hints of relevance to lymphocyte biology and therapeutic interventions with NAMPT inhibitors.

Ultrasound in the follow-up of young patients with malignant ovarian tumors after conservative surgery

Ultrasound examinations were performed us a step in the follow-up of 62 patients previously treated with conservative surgery for malignant ovarian tumors. With a minimal follow-up period of 36 months (range 36-129) 12 recurrences of disease were observed in nine patients. When compared to other routine follow-up procedures, ultrasound examination proved to be the most effective procedure in the monitoring of these patients, correctly detecting ten recurrences. Physical and gynecological examinations detected seven, tumor marker measurements detected six and chest X-rays detected one. Ultrasound examination was 83% sensitive, 99% specific and 99% accurate in the detection of recurrent disease. In four recurrences leading to death, the diameters of the tumors at first detection were 25, 50, 50 and 100 mm, significantly higher (p = 0.03) than in seven recurrences followed by complete response of the tumor (range 15-35 mm, median 30 mm). Ultrasound appears to be superior to physical and gynecological examination in early detection of recurrence; considering that smaller burdens of tumor at the time of recurrence seem to imply a better prognosis, ultrasound should be considered us a useful additional procedure in the follow-up of these patients.

SIRT1-dependent restoration of NAD+ homeostasis after increased extracellular NAD+ exposure

In the last several years, NAD+ supplementation has emerged as an innovative and safe therapeutic strategy for a wide spectrum of disorders, including diabetes and neuropathy. However, critical questions remain as to how NAD+ and its precursors are taken up by cells, as well as the effects of long-lasting intracellular NAD+ (iNAD+) increases. Here, we investigated the kinetics of iNAD+ levels in different cell types challenged with prolonged exposure to extracellular NAD+ (eNAD+). Surprisingly, we found that after the initial increase, iNAD+ contents decreased back to control levels (iNAD+ resetting). Focusing our attention on HeLa cells, we found that oxygen and ATP consumption occurred with similar temporal kinetics after eNAD+ exposure. Using [³H]NAD+ and [¹⁴C]NAD+, we determined that NAD+ resetting was not due to increased dinucleotide extrusion but rather due to reduced uptake of cleaved NAD+ products. Indeed, eNAD+ exposure reduced the expression of the ecto-5′-nucleotidase CD73, the nicotinamide adenine mononucleotide transporter solute carrier family 12 member 8, and the nicotinamide riboside kinase. Interestingly, silencing the NAD+-sensor enzyme sirtuin 1 prevented eNAD+-dependent transcriptional repression of ecto-5′-nucleotidase, solute carrier family 12 member 8, and nicotinamide riboside kinase, as well as iNAD+ resetting. Our findings provide the first evidence for a sirtuin 1–mediated homeostatic response aimed at maintaining physiological iNAD+ levels in conditions of excess eNAD+ availability. These data may be of relevance for therapies designed to support the NAD+ metabolome via extracellular supplementation of the dinucleotide or its precursors.

Discovery of M3 Antagonist-PDE4 Inhibitor Dual Pharmacology Molecules for the Treatment of Chronic Obstructive Pulmonary Disease

In this paper, we report the discovery of dual M₃ antagonist-PDE4 inhibitor (MAPI) compounds for the inhaled treatment of pulmonary diseases. The identification of dual compounds was enabled by the intuition that the fusion of a PDE4 scaffold derived from our CHF-6001 series with a muscarinic scaffold through a common linking ring could generate compounds active versus both the transmembrane M₃ receptor and the intracellular PDE4 enzyme. Two chemical series characterized by two different muscarinic scaffolds were investigated. SAR optimization was aimed at obtaining M₃ nanomolar affinity coupled with nanomolar PDE4 inhibition, which translated into anti-bronchospastic efficacy ex vivo (inhibition of rat trachea contraction) and into anti-inflammatory efficacy in vitro (inhibition of TNFα release). Among the best compounds, compound 92a achieved the goal of demonstrating in vivo efficacy and duration of action in both the bronchoconstriction and inflammation assays in rat after intratracheal administration.

Optimization of M3 Antagonist-PDE4 Inhibitor (MAPI) Dual Pharmacology Molecules for the Treatment of COPD

Aiming at the inhaled treatment of pulmonary diseases, the optimization process of the previously reported MAPI compound 92a is herein described. The project was focused on overcoming the chemical stability issue and achieving a balanced bronchodilator/anti-inflammatory profile in rats in order to be confident in a clinical effect without having to overdose at one of the biological targets. The chemical strategy was based on fine-tuning of the substitution pattern in the muscarinic and PDE4 structural portions of the dual pharmacology compounds, also making use of the analysis of a proprietary crystal structure in the PDE4 catalytic site. Compound 10f was identified as a chemically stable, potent, and in vivo balanced MAPI lead compound, as assessed in bronchoconstriction and inflammation assays in rats after intratracheal administration. After the in-depth investigation of the pharmacological and solid-state profile, 10f proved to be safe and suitable for development.

Calf pseudohypertrophy in a patient with double neurogenic pathology

A pseudohypertrophy of the calf can be rarely associated with neurogenic pathologies as S-1 radiculopathy, poliomyelitis, spinal muscular atrophy, traumatic lesions of peripheral nerves, intraspinal neurinoma. The causes of this particular phenomenon are unknown. The authors present the case of a 52-year-old man with an enlargement of the left calf suffering from a mild form of spinal paralytic poliomyelitis in the early childhood and episodes of severe left sciatica in the last four years. Electromyography demonstrated a pattern of denervation in both legs and an H-reflex absent when the left tibial nerve was stimulated. An open muscle biopsy of the left calf was performed. Light microscopic and ultrastructural examination of the muscle confirmed the presence of a pattern of "neurogenic type" pseudohypertrophy. Our results could be interesting for the understanding of the mechanism of neurogenic pseudohypertrophy. This case suggests that timing of stimulus or "dose" of denervation may be important factors in such a phenomenon.

Impact on beclometasone dipropionate pharmacokinetics when switching to a low global warming potential propellant in a pressurised metered-dose inhaler

INTRODUCTION

Use of high global warming potential propellants (e.g., HFA-134a) for pressurised metered-dose inhalers (pMDIs) is being phased down. Beclometasone dipropionate (BDP) is approved for the treatment of asthma in several countries via an HFA-134a propellant pMDI. This is being reformulated using the low global warming potential propellant HFA-152a. Two studies compared BDP pharmacokinetics delivered via pMDI using HFA-152a vs HFA-134a.

METHODS

Both studies (N = 71/study) were single-dose (four inhalations of BDP), randomised, double-blind, crossover (Study 1, four-way; Study 2, two-way), in healthy volunteers. In Study 1, subjects inhaled BDP via HFA-134a pMDI in two periods (200 μg/actuation in one period, 100 μg/actuation in the other) and HFA-152a pMDI in the other two (200 or 100 μg/actuation). In Study 2, subjects inhaled BDP 200 μg/actuation via HFA-134a or HFA-152a pMDI using a spacer device. pMDIs containing HFA-152a and HFA-134a were compared in terms of lung availability (BDP comparisons) and total systemic exposure (beclometasone-17-monopropionate comparisons [B17MP; active metabolite of BDP]), with bioequivalence concluded if the 90 % confidence intervals (CIs) of the geometric mean ratios of maximum plasma concentration (Cmax) and area under the plasma concentration-time curve between time zero and the last quantifiable timepoint (AUC0-t) were between 80 and 125 %.

RESULTS

BDP Cmax and AUC0-t were equivalent for the two BDP 200 μg formulations, without (Study 1) and with spacer (Study 2). BDP 100 μg AUC0-t met the bioequivalence criteria, but the Cmax lower 90 % CI was marginally below the bioequivalence limit (79.46 %). B17MP Cmax and AUC0-t were bioequivalent with both propellants in all three comparisons.

CONCLUSIONS

Overall, bioequivalence was confirmed of HFA-152a and HFA-134a for BDP 200 μg/actuation, with and without a spacer. Although bioequivalence of the two formulations cannot be formally concluded for BDP 100 μg, the minimal difference suggests the two formulations can be considered therapeutically equivalent.

[Histopathologic examination of the intervertebral lumbar disk. Evaluation of its usefulness and limitations]

A retrospective clinical-pathological review of 192 lumbar intervertebral discs removed via an interlaminar approach or percutaneous nucleotomy from patients suffering from sciatic pain was carried out in order to assess if routine examination is useful. Only for a case of our series, which showed ill defined features at preoperative neuroradiologic imaging, an intraoperative pathologic examination was necessary. Immunohistochemical study was never required. A routine examination with a hematoxilin-eosin stain was sufficient also to recognize postoperative scar in patients reoperated. In conclusion we think that routine examination of the intervertebral disc is a procedure which is not expensive and useful to assess the nature of the lesion in reoperated patients and in rare cases showing unclear radiologic pattern.

Time-course transcriptome analysis of a double challenge bleomycin-induced lung fibrosis rat model uncovers ECM homoeostasis-related translationally relevant genes

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is an irreversible disorder with a poor prognosis. The incomplete understanding of IPF pathogenesis and the lack of accurate animal models is limiting the development of effective treatments. Thus, the selection of clinically relevant animal models endowed with similarities with the human disease in terms of lung anatomy, cell biology, pathways involved and genetics is essential. The bleomycin (BLM) intratracheal murine model is the most commonly used preclinical assay to evaluate new potential therapies for IPF. Here, we present the findings derived from an integrated histomorphometric and transcriptomic analysis to investigate the development of lung fibrosis in a time-course study in a BLM rat model and to evaluate its translational value in relation to IPF.

METHODS

Rats were intratracheally injected with a double dose of BLM (days 0-4) and sacrificed at days 7, 14, 21, 28 and 56. Histomorphometric analysis of lung fibrosis was performed on left lung sections. Transcriptome profiling by RNAseq was performed on the right lung lobes and results were compared with nine independent human gene-expression IPF studies.

RESULTS

The histomorphometric and transcriptomic analyses provided a detailed overview in terms of temporal gene-expression regulation during the establishment and repair of the fibrotic lesions. Moreover, the transcriptomic analysis identified three clusters of differentially coregulated genes whose expression was modulated in a time-dependent manner in response to BLM. One of these clusters, centred on extracellular matrix (ECM)-related process, was significantly correlated with histological parameters and gene sets derived from human IPF studies.

CONCLUSIONS

The model of lung fibrosis presented in this study lends itself as a valuable tool for preclinical efficacy evaluation of new potential drug candidates. The main finding was the identification of a group of persistently dysregulated genes, mostly related to ECM homoeostasis, which are shared with human IPF.