The mitochondriogenic but not the immunosuppressant effects of mTOR inhibitors prompt neuroprotection and delay disease evolution in a mouse model of progressive multiple sclerosis.

INTRODUCTION: Purportedly, the progression of multiple sclerosis (MS) occurs when neurodegenerative processes due to derangement of axonal bioenergetics take over the autoimmune response. However, a clear picture of the causative interrelationship between autoimmunity and axonal mitochondrial dysfunction in progressive MS (PMS) pathogenesis waits to be provided. METHODS: In the present study, by adopting the NOD mouse model of PMS, we compared the pharmacological effects of the immunosuppressants dexamethasone and fingolimod with those of mTOR inhibitors rapamycin and everolimus that, in addition to immunosuppression, also regulate mitochondrial functioning. Female Non-Obese Diabetic (NOD) mice were immunized with MOG35-55 and treated with drugs to evaluate functional, immune and mitochondrial parameters during disease evolution. RESULTS: We found that dexamethasone and fingolimod did not affect the pattern of progression as well as survival. Conversely, mTOR inhibitors rapamycin and everolimus delayed disease progression and robustly extended survival of immunized mice. The same effects were obtained when treatment was delayed by 30 days after immunization. Remarkably, dexamethasone and fingolimod prompted the same degree of immunosuppression of rapamycin within both spleen and spinal cord of mice. However, only rapamycin prompted mitochondriogenesis by increasing mitochondrial content, and expression of several mitochondrial respiratory complex subunits, thereby preventing mtDNA reduction in the spinal cords of immunized mice. These pharmacodynamic effects were not reproduced in healthy NOD mice, suggesting a disease context-dependent pharmacodynamic effect. DISCUSSION: Data corroborate the key role of mitochondriogenesis to treatment of MS progression, and for the first time disclose the translational potential of mTOR inhibitors in PMS therapy.

Early derangement of axonal mitochondria occurs in a mouse model of progressive but not relapsing-remitting multiple sclerosis.

INTRODUCTION: Derangement of axonal mitochondrial bioenergetics occurs during progressive multiple sclerosis (PMS). However, whether this is a delayed epiphenomenon or an early causative event of disease progression waits to be understood. Answering this question might further our knowledge of mechanisms underlying neurobiology of PMS and related therapy. METHODS: MOG35-55-immunized NOD and PLP139-151-immunized SJL female mice were adopted as models of progressive or relapsing-remitting experimental autoimmune encephalomyelitis (EAE), respectively. Multiple parameters of mitochondrial homeostasis were analyzed in the mouse spinal cord during the early asymptomatic stage, also evaluating the effects of scavenging mitochondrial reactive oxygen species with Mito-TEMPO. RESULTS: Almost identical lumbar spinal cord immune infiltrates consisting of Th1 cells and neutrophils without B and Th17 lymphocytes occurred early upon immunization in both mouse strains. Still, only NOD mice showed axon-restricted dysregulation of mitochondrial homeostasis, with reduced mtDNA contents and increased cristae area. Increased expression of mitochondrial respiratory complex subunits Nd2, Cox1, Atp5d, Sdha also exclusively occurred in lumbar spinal cord of NOD and not SJL mice. Accordingly, in this region genes regulating mitochondrial morphology (Opa1, Mfn1, Mfn2 and Atp5j2) and mitochondriogenesis (Pgc1α, Foxo, Hif-1α and Nrf2) were induced early upon immunization. A reduced extent of mitochondrial derangement occurred in the thoracic spinal cord. Notably, the mitochondrial radical scavenger Mito-TEMPO reduced H2O2 content and prevented both mtDNA depletion and cristae remodeling, having no effects on dysregulation of mitochondrial transcriptome. DISCUSSION: We provide here the first evidence that axonal-restricted derangement of mitochondrial homeostasis already occurs during the asymptomatic state exclusively in a mouse model of PMS. Data further our understanding of mechanisms related to EAE progression, and point to very early axonal mitochondrial dysfunction as central to the neuropathogenesis of MS evolution.

Switching anti-CGRP(R) monoclonal antibodies in multi-assessed non-responder patients and implications for ineffectiveness criteria: A retrospective cohort study.

BACKGROUND: A pharmacological class effect was initially proposed for monoclonal antibodies against the calcitonin gene related peptide pathway. However, preliminary evidence shows that switching patients who were non-responding to one monoclonal antibody to another could provide some benefit. Herein, we assess treatment response to an anti-calcitonin gene related peptide/receptor monoclonal antibody in patients who have failed to respond to anti-calcitonin gene related peptide/ligand monoclonal antibodies calcitonin gene related peptide/ligand monoclonal antibodies and vice versa. In addition, we select non-responders to the first anti- monoclonal antibody by three or five more stringent variables. METHODS: Retrospective cohort study including outpatients treated consecutively with two anti-calcitonin gene related peptide monoclonal antibodies. Ineffectiveness to the first monoclonal antibody was assessed using three (MIDAS score, monthly headache days, and analgesic monthly days) variables or five (monthly headache days, MIDAS score, analgesic monthly days, analgesic monthly number and HIT-6 score) variables in the same cohort of patients. The primary endpoints were the absolute change from baseline in monthly headache days, response rate, and persistence in medication overuse at three months of treatment with the second anti-CGRP mAb. RESULTS: In patients selected by three variables, a sustained reduction in monthly headache days, analgesic monthly days, MIDAS and HIT-6 scores was observed at month-3 of treatment with the second monoclonal antibody. Ten (45.4%) patients achieved at least a ≥30% response rate. No difference was reported switching anti-CGRP mAb against ligand or receptor. In the patient subgroup selected by five variables, only HIT-6 was reduced from baseline at month-3. However, a trend toward a reduction in monthly headache days, analgesic monthly days, and MIDAS score was observed at month-3. CONCLUSIONS: Switching anti-calcitonin gene related peptide monoclonal antibodies in selected patients might be an option to achieve or improve clinical benefit. More studies are required to establish the effectiveness of switching these treatments.

Validation of the Italian version of the Cluster Headache Impact Questionnaire (CHIQ).

BACKGROUND: The Cluster Headache Impact Questionnaire (CHIQ) is a specific and easy-to-use questionnaire to assess the current impact of cluster headache (CH). The aim of this study was to validate the Italian version of the CHIQ. METHODS: We included patients diagnosed with episodic CH (eCH) or chronic CH (cCH) according to the ICHD-3 criteria and included in the "Italian Headache Registry" (RICe). The questionnaire was administered to patients through an electronic form in two sessions: at first visit for validation, and after 7 days for test-retest reliability. For internal consistency, Cronbach's alpha was calculated. Convergent validity of the CHIQ with CH features and the results of questionnaires assessing anxiety, depression, stress, and quality of life was evaluated using Spearman's correlation coefficient. RESULTS: We included 181 patients subdivided in 96 patients with active eCH, 14 with cCH, and 71 with eCH in remission. The 110 patients with either active eCH or cCH were included in the validation cohort; only 24 patients with CH were characterized by a stable attack frequency after 7 days, and were included in the test-retest cohort. Internal consistency of the CHIQ was good with a Cronbach alpha value of 0.891. The CHIQ score showed a significant positive correlation with anxiety, depression, and stress scores, while showing a significant negative correlation with quality-of-life scale scores. CONCLUSION: Our data show the validity of the Italian version of the CHIQ, which represents a suitable tool for evaluating the social and psychological impact of CH in clinical practice and research.

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.

Effects of cluster headache preventatives on mouse hypothalamic transcriptional homeostasis.

OBJECTIVE: To investigate how cluster headache preventatives verapamil, lithium and prednisone affect expression of hypothalamic genes involved in chronobiology. METHODS: C57Bl/6 mice were exposed to daily, oral treatment with verapamil, lithium, prednisone or amitriptyline (as negative control), and transcripts of multiple genes quantified in the anterior, lateral and posterior hypothalamus. RESULTS: Verapamil, lithium or prednisone did not affect expression of clock genes of the anterior hypothalamus (Clock, Bmal1, Cry1/2 and Per1/2). Prednisone altered expression of hypothalamic neuropeptides melanin-concentrating hormone and histidine decarboxylase within the lateral and posterior hypothalamus, respectively. The three preventatives did not affect expression of the neurohypophyseal hormones oxytocin and arginine-vasopressin in the posterior hypothalamus. Conversely, amitriptyline reduced mRNA levels of Clock, oxytocin and arginine-vasopressin. CONCLUSION: Data suggest that cluster headache preventatives act upstream or downstream from the hypothalamus. Our findings provide new insights on hypothalamic homeostasis during cluster headache prophylaxis, as well as neurochemistry underlying cluster headache treatment.

Effectiveness of anti-CGRP monoclonal antibodies on central symptoms of migraine.

BACKGROUND: Clinical trials and observational studies with anti-calcitonin gene-related peptide antibodies poorly investigated their impact on migraine prodromal and accompanying symptoms. This information might help deciphering the biologics' pharmacodynamic and provide hints on migraine pathogenesis. Herein, we report the effects of erenumab, fremanezumab and galcanezumab on attack prodromal and accompanying symptoms and on neurological and psychiatric traits. . METHODS: An explorative, prospective, questionnaire-based study was completed by a cohort (n = 80) of patients with chronic migraine patients presenting a sustained reduction of ≥50% of Migraine Disability Assessment Score and ≥30% of monthly migraine days three months after anti-calcitonin gene-related peptide antibodies treatment. RESULTS: The majority of patients experienced a complete prevention of migraine symptoms without evidence of initial onset followed by attack abortion. Few patients reported the recurrence of prodromal (from 10% to 12.5%) or accompanying (from 1.3% to 8.8%) symptoms without headache. All patients with migraine with aura reported a decrease of aura incidence. Sleep changes (51.2%), increase in appetite (20.0%) and weight (18.8%) as well as a reduction in stress (45.0%), anxiety (26.3%), and panic attacks (15%) were also reported. CONCLUSION: Anti-calcitonin gene-related peptide antibodies seems to significantly impact brain functions of migraineurs, preventing not only migraine headache but also its anticipatory and accompanying symptoms.

Predictors of sustained response and effects of the discontinuation of anti-calcitonin gene related peptide antibodies and reinitiation in resistant chronic migraine.

BACKGROUND AND PURPOSE: Guidelines for migraine prophylaxis suggest stopping medication after 6-12 months to reevaluate treatment appropriateness. The Italian Medicines Agency set a mandatory regulation to stop anti-calcitonin gene related protein (CGRP) pathway monoclonal antibody (anti-CGRP mAb) treatments for 3 months after 12 months of treatment. Herein, the effects of discontinuation and retreatment of anti-CGRP mAbs in resistant chronic migraine patients are assessed, evaluating predictive factors of sustained response. METHODS: This was a monocentric prospective cohort study, enrolling 44 severe (resistant to ≥3 preventive treatments) chronic migraine patients (all with medication-overuse), treated with erenumab (54.5%) or galcanezumab (45.5%) for 12 months, who discontinued treatment for 3 months and then restarted for 1 month. RESULTS: Overall, patients reported an increasing deteriorating trend during the 3 months of discontinuation. Monthly migraine days, number of analgesics, days with at least one analgesic used, a ≥50% response rate (reduction in monthly migraine days), and Migraine Disability Assessment Score and Headache Impact Test 6 total score, remained lower than baseline values, but increased compared to month 12 of treatment. All outcome measures decreased again during the month of retreatment. Patients who did not meet criteria for restarting treatment had a lower Migraine Disability Assessment Score (p = 0.03) and Headache Impact Test 6 (p = 0.01) score at baseline and better outcome measures during discontinuation compared to patients who restarted treatment. CONCLUSIONS: In most patients, the 3-month discontinuation of anti-CGRP mAbs resulted in progressive migraine deterioration that was rapidly reverted by retreatment. However, one-quarter of patients who reported better quality of life indices before treatment showed a sustained benefit during discontinuation and did not need retreatment.

Mental pain as a global person-centered outcome measure.

BACKGROUND: Mental pain has been proposed as a global person-centered outcome measure. The aim of this cross-sectional study was to test an essential requisite of such a measure, namely that mental pain incorporates independent contributions from a range of discrete but disparate outcome measures. METHODS: Two hundred migraine patients were assessed concerning migraine disability, psychosomatic syndromes, mental pain, depression, anxiety, and psychosocial dimensions. General linear models were tested to verify which measures would individually make unique contributions to overall mental pain. RESULTS: The final model, accounting for 44% of variance, identified that higher mental pain was associated with more severe depressive symptoms, higher migraine disability, lower well-being, and poorer quality of life. CONCLUSION: In this sample, mental pain was shown to behave as expected of a global outcome measure, since multiple measures of symptomatology and quality of life showed modest but significant bivariate correlations with mental pain and some of these measures individually made unique contributions to overall mental pain.

Mental pain and pain-proneness in patients with migraine: results from the PAINMIG cohort-study.

BACKGROUND: Pain has been qualified under four categories: nociception, perception of pain, suffering, and pain behaviors. Most of the literature on migraine has devoted attention to the first two. The aim of the present cohort study was to investigate patients with migraine enrolled at a tertiary care unit to study suffering and mental pain and identify potential risk factors for migraine. METHODS: An observational cross-sectional study was carried out on patients with chronic migraine (CM) and episodic migraine (EM), and healthy subjects (HS). The three groups were matched for age and sex. A comprehensive assessment of migraine disability, pain, psychiatric disorders, psychosomatic syndromes, depressive and anxious symptoms, euthymia, psychosocial variables, mental pain, and pain-proneness (PP) was performed. RESULTS: Three hundred subjects were enrolled (100 CM, 100 EM, and 100 HS). Based on the multiple regression analyses, those presenting PP (social impairment: odds ratio [OR] = 3.59, 95% confidence interval [CI] = 1.14-11.29; depressive symptoms: OR = 3.82, 95% CI = 1.74-8.41) were more likely to be CM than HS. Those with higher levels of PP (social impairment: OR = 4.04, 95% CI = 1.60-10.22; depressive symptoms: OR = 2.02, 95% CI = 1.26-3.24) were more likely to be EM than HS. Those presenting higher levels of mental pain were more likely to be CM than EM (OR = 1.45, 95% CI = 1.02-2.07). CONCLUSION: Migraine is an unpleasant sensory and emotional experience associated with psychosocial manifestations that might contribute to the level of suffering of the individuals. Mental pain resulted to be the variable that most differentiated patients with CM from EM.

Low-dose methadone for refractory chronic migraine accompanied by medication-overuse headache: a prospective cohort study.

OBJECTIVES: A refractory chronic migraine (RCM) accompanied by medication-overuse headache (MOH) is an extremely disabling disease. Evidence suggests that in selected patients, chronic opioids may be a valuable therapeutic option for RCM. The aim of the present study was to evaluate the effectiveness and safety of prophylaxis with low-dose methadone (LDM) in patients affected by RCM with continuous headache and MOH. METHODS: A prospective cohort study was performed between May 2012 and November 2015 at the Headache Center and Toxicology Unit of the Careggi University Hospital. Eligible patients were treated with prophylactic LDM and followed up for 12 months. Headache exacerbations, pain intensity, use of rescue medications, and occurrence of adverse drug reactions (ADRs) were recorded. RESULTS: Thirty patients (24 females, median age 48 years) were enrolled. Nineteen (63%) patients dropped out, mainly because of early ADRs (n = 10), including nausea, vomiting, and constipation. At last available follow-up, LDM was associated with a significant decrease in the number of headache attacks/month (from a median of 45 (interquartile range 30-150) to 16 (5-30), p < 0.001), in pain intensity (from 8.5 (8-9) to 5 (3-6), p < 0.001), and in the number of rescue medications consumed per month (from 95 (34-240) to 15 (3-28), p < 0.001). No misuse or diversion cases were observed. CONCLUSION: LDM could represent a valuable and effective option in selected patients affected by RCM with continuous headache and MOH, although the frequency of early ADRs poses major safety concerns. Randomized controlled trials are needed to confirm the efficacy and safety of LDM prophylaxis.

Ultra-rapid brain uptake of subcutaneous sumatriptan in the rat: Implication for cluster headache treatment.

BACKGROUND: In spite of the substantial therapeutic efficacy of triptans, their site of action is still debated. Subcutaneous sumatriptan is the most efficacious symptomatic treatment for cluster headache (CH) patients, showing therapeutic onset within a few minutes after injection even in migraine patients. However, whether subcutaneous sumatriptan is able to reach the CNS within this short time frame is currently unknown. METHODS: Here, by means of liquid chromatography/mass spectrometry, we investigated peripheral and brain distribution of subcutaneous sumatriptan soon after injection in rats at a dose equivalent to that used in patients. Tissue sumatriptan contents were compared to those of oxazepam, a prototypical lipophilic, neuroactive drug. RESULTS: We report that sumatriptan accumulated within brain regions of relevance to migraine and CH pathogenesis such as the hypothalamus and the brainstem as soon as 1 and 5 minutes after injection. Notably, sumatriptan brain distribution was faster than that of oxazepam, reaching concentrations exceeding its reported binding affinity for 5HT1B/D receptors, and in the range of those able to inhibit neurotransmitter release in vivo. CONCLUSION: Our findings indicate that sumatriptan distributes within the CNS soon after injection, and are in line with prompt pain relief by parenteral sumatriptan in CH patients.

Cell cycle activation in p21 dependent pathway: An alternative mechanism of organophosphate induced dopaminergic neurodegeneration.

In the previous study, we demonstrated that dichlorvos induces oxidative stress in dopaminergic neuronal cells and subsequent caspase activation mediates apoptosis. In the present study, we evaluated the effect and mechanism of dichlorvos induced oxidative stress on cell cycle activation in NGF-differentiated PC12 cells. Dichlorvos exposure resulted in oxidative DNA damage along with activation of cell cycle machinery in differentiated PC12 cells. Dichlorvos exposed cells exhibited an increased expression of p53, cyclin-D1, pRb and decreased expression of p21suggesting a re-entry of differentiated cells into the cell cycle. Cell cycle analysis of dichlorvos exposed cells revealed a reduction of cells in the G0/G1 phase of the cell cycle (25%), and a concomitant increase of cells in S phase (30%) and G2/M phase (43.3%) compared to control PC12 cells. Further, immunoblotting of cytochrome c, Bax, Bcl-2 and cleaved caspase-3 revealed that dichlorvos induces a caspase-dependent cell death in PC12 cells. These results suggest that Dichlorvos exposure has the potential to generate oxidative stress which evokes activation of cell cycle machinery leading to apoptotic cell death via cytochrome c release from mitochondria and subsequent caspase-3 activation in differentiated PC12 cells.

Pharmacological NAD-Boosting Strategies Improve Mitochondrial Homeostasis in Human Complex I-Mutant Fibroblasts.

Mitochondrial disorders are devastating genetic diseases for which efficacious therapies are still an unmet need. Recent studies report that increased availability of intracellular NAD obtained by inhibition of the NAD-consuming enzyme poly(ADP-ribose) polymerase (PARP)-1 or supplementation with the NAD-precursor nicotinamide riboside (NR) ameliorates energetic derangement and symptoms in mouse models of mitochondrial disorders. Whether these pharmacological approaches also improve bioenergetics of human cells harboring mitochondrial defects is unknown. It is also unclear whether the same signaling cascade is prompted by PARP-1 inhibitors and NR supplementation to improve mitochondrial homeostasis. Here, we show that human fibroblasts mutant for the NADH dehydrogenase (ubiquinone) Fe-S protein 1 (NDUFS1) subunit of respiratory complex I have similar ATP, NAD, and mitochondrial content compared with control cells, but show reduced mitochondrial membrane potential. Interestingly, mutant cells also show increased transcript levels of mitochondrial DNA but not nuclear DNA respiratory complex subunits, suggesting activation of a compensatory response. At variance with prior work in mice, however, NR supplementation, but not PARP-1 inhibition, increased intracellular NAD content in NDUFS1 mutant human fibroblasts. Conversely, PARP-1 inhibitors, but not NR supplementation, increased transcription of mitochondrial transcription factor A and mitochondrial DNA-encoded respiratory complexes constitutively induced in mutant cells. Still, both NR and PARP-1 inhibitors restored mitochondrial membrane potential and increased organelle content as well as oxidative activity of NDUFS1-deficient fibroblasts. Overall, data provide the first evidence that in human cells harboring a mitochondrial respiratory defect exposure to NR or PARP-1, inhibitors activate different signaling pathways that are not invariantly prompted by NAD increases, but equally able to improve energetic derangement.

Dysregulation of sphingosine 1 phosphate receptor-1 (S1P1) signaling and regulatory lymphocyte-dependent immunosuppression in a model of post-fingolimod MS rebound.

Fingolimod affords protection from MS by sequestering lymphocytes in secondary lymphoid organs via down regulation of their sphingosine 1 phosphate receptor (S1P1). Unexpectedly, accumulating evidence indicates that patients who discontinue fingolimod treatment may be at risk of rehearsal of magnetic resonance (MR) and clinical disease activity, sometimes featuring dramatic rebound. We therefore developed in vivo and in vitro models of post-fingolimod MS rebound to unravel its cellular and molecular mechanisms. The impact of fingolimod withdrawal on T regulatory lymphocytes was also investigated by means of cytofluorimetric analysis and antigen-specific lymphocyte proliferation assays. We show that mice with relapsing-remitting experimental autoimmune encephalomyelitis (EAE) undergo extremely severe, chronic disease rebound upon discontinuation of fingolimod. Remarkably, rebound is preceded by a burst of S1P1 overexpression in lymph node-entrapped lymphocytes that correlates with subsequent massive lymphocyte egress and widespread CNS immune infiltration. Also, consistent with the ability of S1P1 to counteract polarization and function of T regulatory lymphocytes their number and suppression of effector T cells is reduced by fingolimod suspension. Data disclose the first pathogenic mechanisms of post-fingolimod rebound that may be targeted for therapeutic intervention.

Glucose deprivation converts poly(ADP-ribose) polymerase-1 hyperactivation into a transient energy-producing process.

Massive poly(ADP-ribose) formation by poly(ADP-ribose) polymerase-1 (PARP-1) triggers NAD depletion and cell death. These events have been invariantly related to cellular energy failure due to ATP shortage. The latter occurs because of both ATP consumption for NAD resynthesis and impairment of mitochondrial ATP formation caused by an increase of the AMP/ADP ratio. ATP depletion is therefore thought to be an inevitable consequence of NAD loss and a hallmark of PARP-1 activation. Here, we challenge this scenario by showing that PARP-1 hyperactivation in cells cultured in the absence of glucose (Glu(-) cells) is followed by NAD depletion and an unexpected PARP-1 activity-dependent ATP increase. We found increased ADP content in resting Glu(-) cells, a condition that counteracts the increase of the AMP/ADP ratio during hyperpoly(ADP-ribosyl)ation and preserves mitochondrial coupling. We also show that the increase of ATP in Glu(-) cells is due to adenylate kinase activity, transforming AMP into ADP which, in turn, is converted into ATP by coupled mitochondria. Interestingly, PARP-1-dependent mitochondrial release of apoptosis-inducing factor (AIF) and cytochrome complex (Cyt c) is reduced in Glu(-) cells, even though cell death eventually occurs. Overall, the present study identifies basal ADP content and adenylate kinase as key determinants of bioenergetics during PARP-1 hyperactivation and unequivocally demonstrates that ATP loss is not metabolically related to NAD depletion.

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.

Glaucoma: neuroprotection with NAD-based therapeutic interventions.

Clinical evidence shows that intraocular hypertension is not the primary pathogenetic event of glaucoma, whereas early neurodegeneration of retinal ganglion cells (RGCs) represents a key therapeutic target. Unfortunately, failure of clinical trials with neuroprotective agents, in particular those testing the anti-excitotoxic drug memantine, generated widespread skepticism regarding the possibility of counteracting neurodegeneration during glaucoma. New avenues for neuroprotective approaches to counteract glaucoma evolution have been opened by the identification of a programmed axonal degeneration (PAD) program triggered by increased nicotinamide mononucleotide (NMN)/NAD concentration ratio. Positive results of proof-of-concept clinical studies based on sustaining axonal NAD homeostasis facilitated the design of Phase 2/3 trials. Here, I share my opinion on how neurodegeneration in glaucoma should be put into context, together with an appraisal of the pharmacological rationale of NAD-supporting therapies for use during glaucoma progression.

Switching OnabotulinumtoxinA to Monoclonal Anti-CGRP Antibodies in Drug-Resistant Chronic Migraine.

BACKGROUND: OnabotulinumtoxinA (BTX-A) and anti-calcitonin gene-related peptide (CGRP) monoclonal antibodies (anti-CGRP mAbs) are approved drugs for chronic migraine (CM), a difficult-to-treat condition. Optimization of CM patient management by choosing the best options and determining appropriate time for switching or adding concomitant treatments are highly needed. OBJECTIVE: Evaluate clinical response to anti-CGRP mAbs in patients who switched from BTX-A due to ineffectiveness defined by different cut-offs and assess the retention rate, effectiveness, and safety of both drugs within the first 9 months of treatment. METHODS: A monocentric, cohort study, enrolling patients with CM, resistant to several preventive treatments, first treated with BTX-A and then with anti-CGRP mAbs with two observational phases of 9 months preceded by respective baseline. First, the retention rate and effectiveness of both treatments were measured in all patients. A second analysis assessed effectiveness in patients stratified according to <50 or <30% response rate to BTX-A. The absolute change from baseline in monthly headache days (MHDs), response rate, analgesic use, and persistence in medication overuse (MO) at 3, 6, and 9 months of treatment were recorded. Last observation carried forward (LOCF) analyses, including all patients and assuming no further changes after discontinuation, were performed for all outcomes. RESULTS: Of the 78 enrolled patients (80.8% female, and 89.7% with MO at baseline), 32 (41.0%) received erenumab, 32 (41.0%) galcanezumab, and 14 (18.0%) fremanezumab. Retention rate was 62.2 and 91.0% for BTX-A and 76.9 and 96.2%, for anti-CGRP mAbs at 3 and 9 months of treatment, respectively. At 9 months of treatment, 22.4% of BTX-A patients and 65.0% of anti-CGRP mAbs patients achieved a ≥50% response rate. Anti-CGRP mAbs reduced MHDs, AMN, and AMDs, and decreased the number of MO patients at 9 months. In patients stratified according to <50 or <30% response rate to BTX-A, response rate (≥50% response at 9 months) to anti-CGRP was 62.9 and 57.9%, respectively. LOCF analyses confirmed these findings. No serious adverse events (AEs) were recorded and only two patients discontinued treatment due to AEs. CONCLUSIONS: Difficult-to-treat CM patients who discontinued BTX-A and received anti-CGRP mAbs showed a substantial clinical improvement in migraine-related outcomes. Switching to an anti-CGRP mAb appears to be a viable option in patients with insufficient response after the first 2 cycles with BTX-A. The appropriate variables, cut-offs, and timing to define ineffectiveness and the best time to switch or combine therapies for difficult-to-treat CM need to be investigated further.