Reducing the learning curve of interlaminar full-endoscopic discectomy: mushroom model-simulation training.

PURPOSE: To describe a cheap simulation model used to reduce the learning curve of the interlaminar full-endoscopic discectomy in a pilot study. INTRODUCTION: The steep and difficult learning curve remain one of the main obstacles against the widespread diffusion of interlaminar full endoscopic lumbar discectomy (ILFED). One solution to overcome this learning curve is training with deliberate practice. As realistic models are relatively expensive and cadaver workshops not readily available, we developed a simple and cheap model to train the key steps of the procedure. METHODS: A simple and cheap model were designed. It consists of a king oyster mushroom stalk, a glove finger, a sponge and cotton wool. In order to fix the model to the table and to simulate the level of the patient's skin whereupon the hand of the surgeon relies, a wooden holding device was also used. As the purpose of this pilot study was to evaluate the model as a stimulator, it was tested during an advanced endoscopic training course. RESULTS: A step-by-step learning method with key steps was used by participants attending an advanced ILFED training on expensive realistic models. The model was considered as comparable and enough realistic to train key steps in order to reduce the learning curve and training costs. CONCLUSION: We present an affordable, simple and reproducible training model, which allows for deliberate practice of the key steps of the ILFED procedure. The model may be used by surgeons starting with spinal endoscopy.

[Spinal injury related to alpine winter sports]. / Fractures de la colonne vertébrale lors d'accidents de ski ou autres sports de neige.

Winter sports are the cause of a significant number of spinal injuries in Switzerland. However, the number of patients, the mechanism, the presentation, the diagnosis and the treatment of vertebral fractures have considerably evolved over the last decades. As the hospital of Sion, in Valais, is particularly exposed to these diagnoses, we analyzed two series of prospective cases 30 years apart (1989-1990 and 2019-2020) and propose a review of the main types and mechanisms of fractures, diagnosis, and management for the primary care physician.

Les sports d'hiver sont à l'origine d'un nombre important de lésions de la colonne vertébrale en Suisse. Cependant, le nombre de patients, le mécanisme, la présentation, le diagnostic et le traitement des fractures vertébrales ont considérablement évolué au cours des dernières décennies. L'hôpital de Sion, en Valais, étant particulièrement exposé à ces diagnostics, nous avons analysé deux séries de cas prospectives à 30 ans d'intervalle (1989-1990 et 2019-2020) et proposons une revue des principaux types et mécanismes de fractures, diagnostics, et prises en charge pour le médecin de premier recours.

A case of subependymal giant cell astrocytoma without tuberous sclerosis complex and review of the literature.

Subependymal giant cell astrocytoma (SEGA) is a World Health Organization (WHO) grade I tumor most commonly seen in the context of the underlying tuberous sclerosis complex (TSC). SEGA in the absence of TSC is exceedingly rare. We report the youngest known case of SEGA in the absence of genetic or phenotypic evidence of TSC with a 10-year follow-up. We discuss the literature surrounding isolated SEGA including an approach to diagnosis, management, and prognosis.

Surgical management of symptomatic cavum septum pellucidum cysts: systematic review of the literature.

Cavum septum pellucidum (CSP) and cavum vergae (CV) cysts are commonly found incidentally. They are usually asymptomatic but may present with symptoms related to obstructive hydrocephalus. There is no consensus about the management of symptomatic CSP and CV cysts. We present, to the best of our knowledge, the first systematic review of the different treatment options for symptomatic CSP and CV cysts. We conducted a literature review using PubMed database, searching for cases of symptomatic CSP and CV cysts managed surgically, and published until April 2019. Preoperative characteristics, surgical procedure, and postoperative outcome were analyzed using SPSS® software (Statistical Package for Social Sciences, IBM®). We found 54 cases of symptomatic CSP and CV cysts managed surgically (34 males, 20 females, 1.7/1 male to female ratio). Mean age was 24.3 ± 20.1 years. The most common presentation was headaches (34 patients, 62%), followed by psychiatric symptoms (27 patients, 49.1%). Preoperative radiological hydrocephalus was present in 30 patients (54.5%). The most common surgical procedure was endoscopic fenestration (39 patients, 70.9%), followed by shunting (10 patients, 18.2%), open surgery (3 patients, 5.5%), and stereotactic fenestration (1 patient, 1.8%). Complete resolution of symptoms was achieved in 36 patients (65.5%) and partial resolution in 7 patients (12.7%), and symptoms were unchanged in 2 patients. The present review suggests that surgical treatment could provide resolution of the symptoms in most of the cases, regardless of the procedure performed. Although mean follow-up was short among the studies, recurrence rate was low.

Implementation of cisternostomy as adjuvant to decompressive craniectomy for the management of severe brain trauma.

OBJECTIVE: To evaluate the value of an adjuvant cisternostomy (AC) to decompressive craniectomy (DC) for the management of patients with severe traumatic brain injury (sTBI). METHODS: A single-center retrospective quality control analysis of a consecutive series of sTBI patients surgically treated with AC or DC alone between 2013 and 2018. A subgroup analysis, "primary procedure" and "secondary procedure", was also performed. We examined the impact of AC vs. DC on clinical outcome, including long-term (6 months) extended Glasgow outcome scale (GOS-E), the duration of postoperative ventilation, and intensive care unit (ICU) stay, mortality, Glasgow coma scale at discharge, and time to cranioplasty. We also evaluated and analyzed the impact of AC vs. DC on post-procedural intracranial pressure (ICP) and brain tissue oxygen (PbO2) values as well as the need for additional osmotherapy and CSF drainage. RESULTS: Forty patients were examined, 22 patients in the DC group, and 18 in the AC group. Compared with DC alone, AC was associated with significant shorter duration of mechanical ventilation and ICU stay, as well as better Glasgow coma scale at discharge. Mortality rate was similar. At 6-month, the proportion of patients with favorable outcome (GOS-E ≥ 5) was higher in patients with AC vs. DC [10/18 patients (61%) vs. 7/20 (35%)]. The outcome difference was particularly relevant when AC was performed as primary procedure (61.5% vs. 18.2%; p = 0.04). Patients in the AC group also had significant lower average post-surgical ICP values, higher PbO2 values and required less osmotic treatments as compared with those treated with DC alone. CONCLUSION: Our preliminary single-center retrospective data indicate that AC may be beneficial for the management of severe TBI and is associated with better clinical outcome. These promising results need further confirmation by larger multicenter clinical studies. The potential benefits of cisternostomy should not encourage its universal implementation across trauma care centers by surgeons that do not have the expertise and instrumentation necessary for cisternal microsurgery. Training in skull base and vascular surgery techniques for trauma care surgeons would avoid the potential complications associated with this delicate procedure.

Posterior wall acetabular fracture in a 13-year-old boy treated by open reduction and mini-plate internal fixation: long-term follow-up of 17 years.

BACKGROUND: Acetabular fractures are uncommon in children and adolescents, mainly because of predominant cartilaginous component and strong surrounding ligaments. Although acetabular fractures at this age can lead to significant disability, there is no consensus regarding management, which continues to be controversial. Particularly, long-term outcome after operative management has not been evaluated. CASE PRESENTATION: We report a case of a 13-year-old boy skeletally immature who presented with an isolated acetabular fracture involving the posterior wall secondary to a traumatic hip dislocation. A Kocher-Langenbeck approach with a surgical luxation of the hip was used for reduction and mini-plate internal fixation of the fracture. Long-term (17-year) follow-up showed a good clinical outcome and a good congruence of the. The patient has bilateral beginning osteoarthritis due to a cam configuration of both hips CONCLUSION: We describe a case of successful operative management of an acetabulum fracture in a skelettaly immature child with a long-term follow-up. Aggressive management of this rare type of fractures may lead to durable positive outcome.

Multimodal Regional Brain Monitoring of Tissue Ischemia in Severe Cerebral Venous Sinus Thrombosis.

BACKGROUND: Comatose critically ill patients with severe diffuse cerebral venous thrombosis (CVT) are at high risk of secondary hypoxic/ischemic insults, which may considerably worsen neurological recovery. Multimodal brain monitoring (MBM) may therefore improve patient care in this setting, yet no data are available in the literature. METHODS: We report two patients with coma following severe diffuse CVT who underwent emergent invasive MBM with intracranial pressure (ICP), brain tissue oximetry (PbtO2), and cerebral microdialysis (CMD). Therapy of CVT consisted of intravenous unfractionated heparin (UFH), followed by endovascular mechanical thrombectomy (EMT). EMT efficacy was assessed continuously at the bedside using MBM. RESULTS: Despite effective therapeutic UFH (aPTT two times baseline levels in the two subjects), average CMD levels of lactate and glucose in the 6 h prior to EMT displayed evidence of regional brain ischemia. The EMT procedure was associated with a rapid (within 6 h) improvement in both CMD lactate (6.42 ± 0.61 4.89 ± 0.55 mmol/L, p = 0.02) and glucose (0.49 ± 0.17 vs. 0.96 ± 0.32 mmol/L, p = 0.0005). EMT was also associated with a significant increase in PbtO2 (22.9 ± 7.5 vs. 30.1 ± 3.6 mmHg, p = 0.0003) and a decrease in CMD glutamate (12.69 ± 1.06 vs. 5.73 ± 1.76 µmol/L, p = 0.017) and intracranial pressure (ICP) (13 ± 4 vs. 11 ± 4 mmHg (p = 004). Patients did not require surgical decompression, regained consciousness, and were discharged from the hospital with a good neurological outcome (modified Rankin score 3 and 4). CONCLUSIONS: This study illustrates the potential utility of continuous bedside MBM in patients with coma after severe brain injury, irrespective of the primary acute cerebral condition. Despite adequate ICP and PbtO2 control, the presence of CMD signs of regional brain cell ischemia triggered emergent EMT to treat CVT, which was associated with a significant and clinically relevant improvement of intracerebral physiology.

Correlation between Papilledema and Intracranial Hypertension in Crouzon Syndrome: A Case Report and Review of the Literature.

Crouzon syndrome represents the most common syndromic craniosynostosis. Ocular complications are frequent, including papilledema and optic atrophy, often related to increased intracranial pressure (ICP). However, there is a poor correlation between ICP normalization and resolution of papilledema. We describe the case of a 6-month-old infant who presented with typical phenotypic features of Crouzon syndrome. Pre- and postoperative ICP monitoring was used. Papilledema persisted despite ICP improvement after decompressive craniectomy. Possible causes of papilledema in this syndromic craniosynostosis are discussed in light of the existing literature.

Cortical cytoskeleton dynamics regulates plasma membrane calcium ATPase isoform-2 (PMCA2) activity.

We have previously shown that purified actin can directly bind to human plasma membrane Ca2+ ATPase 4b (hPMCA4b) and exert a dual modulation on its Ca2+-ATPase activity: F-actin inhibits PMCA while short actin oligomers may contribute to PMCA activation. These studies had to be performed with purified proteins given the nature of the biophysical and biochemical approaches used. To assess whether a functional interaction between the PMCAs and the cortical cytoskeleton is of physiological relevance, we characterized this phenomenon in the context of a living cell by monitoring in real-time the changes in the cytosolic calcium levels ([Ca2+]CYT). In this study, we tested the influence of drugs that change the actin and microtubule polymerization state on the activity and membrane expression of the PMCA transiently expressed in human embryonic kidney (HEK293) cells, which allowed us to observe and quantify these relationships in a live cell, for the first time. We found that disrupting the actin cytoskeleton with cytochalasin D significantly increased PMCA-mediated Ca2+ extrusion (~50-100%) whereas pre-treatment with the F-actin stabilizing agent jasplakinolide caused its full inhibition. When the microtubule network was disrupted by pretreatment of the cells with colchicine, we observed a significant decrease in PMCA activity (~40-60% inhibition) in agreement with the previously reported role of acetylated tubulin on the calcium pump. In none of these cases was there a difference in the level of expression of the pump at the cell surface, thus suggesting that the specific activity of the pump was the regulated parameter. Our results indicate that PMCA activity is profoundly affected by the polymerization state of the cortical cytoskeleton in living cells.

Three-dimensional printing of a sinus pericranii model: technical note.

BACKGROUND: Sinus pericranii (SP) is a rare venous malformation consisting of a single or multiple abnormal emissary veins communicating between intracranial sinuses and dilated epicranial veins. There is no consensus concerning diagnosis, management, and treatment of SP. TECHNICAL NOTE: We report the case of a 4-month-old infant with a SP for whom we used a three-dimensional printed model in order to define the angioarchitecture, improve management, and help parents' understanding of this uncommon condition.

Mutation in the Monocarboxylate Transporter 12 Gene Affects Guanidinoacetate Excretion but Does Not Cause Glucosuria.

A heterozygous mutation (c.643C>A; p.Q215X) in the monocarboxylate transporter 12-encoding gene MCT12 (also known as SLC16A12) that mediates creatine transport was recently identified as the cause of a syndrome with juvenile cataracts, microcornea, and glucosuria in a single family. Whereas the MCT12 mutation cosegregated with the eye phenotype, poor correlation with the glucosuria phenotype did not support a pathogenic role of the mutation in the kidney. Here, we examined MCT12 in the kidney and found that it resides on basolateral membranes of proximal tubules. Patients with MCT12 mutation exhibited reduced plasma levels and increased fractional excretion of guanidinoacetate, but normal creatine levels, suggesting that MCT12 may function as a guanidinoacetate transporter in vivo However, functional studies in Xenopus oocytes revealed that MCT12 transports creatine but not its precursor, guanidinoacetate. Genetic analysis revealed a separate, undescribed heterozygous mutation (c.265G>A; p.A89T) in the sodium/glucose cotransporter 2-encoding gene SGLT2 (also known as SLC5A2) in the family that segregated with the renal glucosuria phenotype. When overexpressed in HEK293 cells, the mutant SGLT2 transporter did not efficiently translocate to the plasma membrane, and displayed greatly reduced transport activity. In summary, our data indicate that MCT12 functions as a basolateral exit pathway for creatine in the proximal tubule. Heterozygous mutation of MCT12 affects systemic levels and renal handling of guanidinoacetate, possibly through an indirect mechanism. Furthermore, our data reveal a digenic syndrome in the index family, with simultaneous MCT12 and SGLT2 mutation. Thus, glucosuria is not part of the MCT12 mutation syndrome.

The Hydroxyl Side Chain of a Highly Conserved Serine Residue Is Required for Cation Selectivity and Substrate Transport in the Glial Glutamate Transporter GLT-1/SLC1A2.

Glutamate transporters maintain synaptic concentration of the excitatory neurotransmitter below neurotoxic levels. Their transport cycle consists of cotransport of glutamate with three sodium ions and one proton, followed by countertransport of potassium. Structural studies proposed that a highly conserved serine located in the binding pocket of the homologous GltPh coordinates L-aspartate as well as the sodium ion Na1. To experimentally validate these findings, we generated and characterized several mutants of the corresponding serine residue, Ser-364, of human glutamate transporter SLC1A2 (solute carrier family 1 member 2), also known as glutamate transporter GLT-1 and excitatory amino acid transporter EAAT2. S364T, S364A, S364C, S364N, and S364D were expressed in HEK cells and Xenopus laevis oocytes to measure radioactive substrate transport and transport currents, respectively. All mutants exhibited similar plasma membrane expression when compared with WT SLC1A2, but substitutions of serine by aspartate or asparagine completely abolished substrate transport. On the other hand, the threonine mutant, which is a more conservative mutation, exhibited similar substrate selectivity, substrate and sodium affinities as WT but a lower selectivity for Na(+) over Li(+). S364A and S364C exhibited drastically reduced affinities for each substrate and enhanced selectivity for L-aspartate over D-aspartate and L-glutamate, and lost their selectivity for Na(+) over Li(+). Furthermore, we extended the analysis of our experimental observations using molecular dynamics simulations. Altogether, our findings confirm a pivotal role of the serine 364, and more precisely its hydroxyl group, in coupling sodium and substrate fluxes.

Neural detection of complex sound sequences in the absence of consciousness.

The neural response to a violation of sequences of identical sounds is a typical example of the brain's sensitivity to auditory regularities. Previous literature interprets this effect as a pre-attentive and unconscious processing of sensory stimuli. By contrast, a violation to auditory global regularities, i.e. based on repeating groups of sounds, is typically detectable when subjects can consciously perceive them. Here, we challenge the notion that global detection implies consciousness by testing the neural response to global violations in a group of 24 patients with post-anoxic coma (three females, age range 45-87 years), treated with mild therapeutic hypothermia and sedation. By applying a decoding analysis to electroencephalographic responses to standard versus deviant sound sequences, we found above-chance decoding performance in 10 of 24 patients (Wilcoxon signed-rank test, P < 0.001), despite five of them being mildly hypothermic, sedated and unarousable. Furthermore, consistently with previous findings based on the mismatch negativity the progression of this decoding performance was informative of patients' chances of awakening (78% predictive of awakening). Our results show for the first time that detection of global regularities at neural level exists despite a deeply unconscious state.

Mutations in SLC1A4, encoding the brain serine transporter, are associated with developmental delay, microcephaly and hypomyelination.

BACKGROUND: L-serine plays an essential role in neuronal development and function. Although a non-essential amino acid, L-serine must be synthesised within the brain because of its poor permeability by the blood-brain barrier. Within the brain, its synthesis is confined to astrocytes, and its shuttle to neuronal cells is performed by a dedicated neutral amino acid transporter, ASCT1. METHODS AND RESULTS: Using exome analysis we identified the recessive mutations, p.E256K, p.L315fs, and p.R457W, in SLC1A4, the gene encoding ASCT1, in patients with developmental delay, microcephaly and hypomyelination; seizure disorder was variably present. When expressed in a heterologous system, the mutations did not affect the protein level at the plasma membrane but abolished or markedly reduced L-serine transport for p.R457W and p.E256K mutations, respectively. Interestingly, p.E256K mutation displayed a lower L-serine and alanine affinity but the same substrate selectivity as wild-type ASCT1. CONCLUSIONS: The clinical phenotype of ASCT1 deficiency is reminiscent of defects in L-serine biosynthesis. The data underscore that ASCT1 is essential in brain serine transport. The SLC1A4 p.E256K mutation has a carrier frequency of 0.7% in the Ashkenazi-Jewish population and should be added to the carrier screening panel in this community.

Sodium/hydrogen exchanger NHA2 is critical for insulin secretion in ß-cells.

NHA2 is a sodium/hydrogen exchanger with unknown physiological function. Here we show that NHA2 is present in rodent and human ß-cells, as well as ß-cell lines. In vivo, two different strains of NHA2-deficient mice displayed a pathological glucose tolerance with impaired insulin secretion but normal peripheral insulin sensitivity. In vitro, islets of NHA2-deficient and heterozygous mice, NHA2-depleted Min6 cells, or islets treated with an NHA2 inhibitor exhibited reduced sulfonylurea- and secretagogue-induced insulin secretion. The secretory deficit could be rescued by overexpression of a wild-type, but not a functionally dead, NHA2 transporter. NHA2 deficiency did not affect insulin synthesis or maturation and had no impact on basal or glucose-induced intracellular Ca(2+) homeostasis in islets. Subcellular fractionation and imaging studies demonstrated that NHA2 resides in transferrin-positive endosomes and synaptic-like microvesicles but not in insulin-containing large dense core vesicles in ß-cells. Loss of NHA2 inhibited clathrin-dependent, but not clathrin-independent, endocytosis in Min6 and primary ß-cells, suggesting defective endo-exocytosis coupling as the underlying mechanism for the secretory deficit. Collectively, our in vitro and in vivo studies reveal the sodium/proton exchanger NHA2 as a critical player for insulin secretion in the ß-cell. In addition, our study sheds light on the biological function of a member of this recently cloned family of transporters.

A Bispecific, Tetravalent Antibody Targeting Inflammatory and Pruritogenic Pathways in Atopic Dermatitis.

Inhibition of IL-4/IL-13 signaling has dramatically improved the treatment of atopic dermatitis (AD). However, in many patients, clinical responses are slow to develop and remain modest. Indeed, some symptoms of AD are dependent on IL-31, which is only partially reduced by IL-4/IL-13 inhibition. Thus, there is an unmet need for AD treatments that concomitantly block IL-4/IL-13 and IL-31 pathways. We engineered NM26-2198, a bispecific tetravalent antibody designed to accomplish this task. In reporter cell lines, NM26-2198 concomitantly inhibited IL-4/IL-13 and IL-31 signaling with a potency comparable with that of the combination of an anti-IL-4Rα antibody (dupilumab) and an anti-IL-31 antibody (BMS-981164). In human PBMCs, NM26-2198 inhibited IL-4-induced upregulation of CD23, demonstrating functional binding to FcγRII (CD32). NM26-2198 also inhibited the secretion of the AD biomarker thymus and activation-regulated chemokine (TARC) in blood samples from healthy human donors. In male cynomolgus monkeys, NM26-2198 exhibited favorable pharmacokinetics and significantly inhibited IL-31-induced scratching at a dose of 30 mg/kg. In a repeat-dose, good laboratory practice toxicology study in cynomolgus monkeys, no adverse effects of NM26-2198 were observed at a weekly dose of 125 mg/kg. Together, these results justify the clinical investigation of NM26-2198 as a treatment for moderate-to-severe AD.

Repetition-induced plasticity of motor representations of action sounds.

Action-related sounds are known to increase the excitability of motoneurones within the primary motor cortex (M1), but the role of this auditory input remains unclear. We investigated repetition priming-induced plasticity, which is characteristic of semantic representations, in M1 by applying transcranial magnetic stimulation pulses to the hand area. Motor evoked potentials (MEPs) were larger while subjects were listening to sounds related versus unrelated to manual actions. Repeated exposure to the same manual-action-related sound yielded a significant decrease in MEPs when right, hand area was stimulated; no repetition effect was observed for manual-action-unrelated sounds. The shared repetition priming characteristics suggest that auditory input to the right primary motor cortex is part of auditory semantic representations.

Traumatic Brain Injury in Alpine Winter Sports: Comparison of Two Case Series from a Swiss Trauma Center 30 Years Apart.

BACKGROUND: Between 3 and 15% of winter sports-related injuries are related to head injuries, which are the primary cause of mortality and disability among skiers. Despite the widespread adoption of helmets in winter sports, which has reduced the incidence of direct head injury, there is a paradoxical trend of an increasing number of individuals wearing helmets sustaining diffuse axonal injuries (DAI), which can result in severe neurologic sequelae. METHODS: We retrospectively reviewed 100 cases collected by the senior author of this work from 13 full winter seasons during the period from 1981 to 1993 and compared them with 17 patients admitted during the more shortened 2019 to 2020 ski season due to COVID-19. All data analyzed come from a single institution. Population characteristics, mechanism of injury, helmet use, need for surgical treatment, diagnosis, and outcome were collected. Descriptive statistics were used to compare the two databases. RESULTS: From February 1981 to January 2020, most skiers with head injuries were men (76% for the 1981-1993 and 85% for 2020). The proportion of patients aged over 50 increased from <20% in 1981 to 65% in 2020 (p < 0.01), with a median age of 60 years (range: 22-83 years). Low- to medium-velocity injuries were identified in 76% (13) of cases during the 2019 to 2020 season against 38% (28/74) during the 1981 to 1993 seasons (p < 0.01). All injured patients during the 2020 season wore a helmet, whereas none of the patients between 1981 and 1993 wore one (p < 0.01). DAI was observed in six cases (35%) for the 2019 to 2020 season against nine cases (9%) for the 1981 to 1993 season (p < 0.01). Thirty-four percent (34) of patients during the 1981 to 1993 seasons and 18% (3) of patients during the 2019 to 2020 season suffered skeletal fractures (p = 0.02). Among the 100 patients of the 1981 to 1993 seasons, 13 (13%) died against 1 (6%) from the recent season during care at the hospital (p = 0.15). Neurosurgical intervention was performed in 30 (30%) and 2 (12%) patients for the 1981 to 1993 and 2019 to 2020 seasons, respectively (p = 0.003). Neuropsychological sequelae were reported in 17% (7/42) of patients from the 1981 to 1993 seasons and cognitive evaluation before discharge detected significant impairments in 24% (4/17) of the patients from the 2019 to 2020 season (p = 0.29). CONCLUSION: Helmet use among skiers sustaining head trauma has increased from none in the period from 1981 to 1993 to 100% during the 2019 to 2020 season, resulting in a reduction in the number of skull fractures and deaths. However, our observations suggest a marked shift in the type of intracranial injuries sustained, including a rise in the number of skiers experiencing DAI, sometimes with severe neurologic outcomes. The reasons for this paradoxical trend can only be speculated upon, leading to the question of whether the perceived benefits of helmet use in winter sports are actually misinterpreted.

An engineered T-cell engager with selectivity for high mesothelin-expressing cells and activity in the presence of soluble mesothelin.

Mesothelin (MSLN) is an attractive immuno-oncology target, but the development of MSLN-targeting therapies has been impeded by tumor shedding of soluble MSLN (sMSLN), on-target off-tumor activity, and an immunosuppressive tumor microenvironment. We sought to engineer an antibody-based, MSLN-targeted T-cell engager (αMSLN/αCD3) with enhanced ability to discriminate high MSLN-expressing tumors from normal tissue, and activity in the presence of sMSLN. We also studied the in vivo antitumor efficacy of this molecule (NM28-2746) alone and in combination with the multifunctional checkpoint inhibitor/T-cell co-activator NM21-1480 (αPD-L1/α4-1BB). Cytotoxicity and T-cell activation induced by NM28-2746 were studied in co-cultures of peripheral blood mononuclear cells and cell lines exhibiting different levels of MSLN expression, including in the presence of soluble MSLN. Xenotransplant models of human pancreatic cancer were used to study the inhibition of tumor growth and stimulation of T-cell infiltration into tumors induced by NM28-2746 alone and in combination with NM21-1480. The bivalent αMSLN T-cell engager NM28-2746 potently induced T-cell activation and T-cell mediated cytotoxicity of high MSLN-expressing cells but had much lower potency against low MSLN-expressing cells. A monovalent counterpart of NM28-2746 had much lower ability to discriminate high MSLN-expressing from low MSLN-expressing cells. The bivalent molecule retained this discriminant ability in the presence of high concentrations of sMSLN. In xenograft models, NM28-2746 exhibited significant tumor suppressing activity, which was significantly enhanced by combination therapy with NM21-1480. NM28-2746, alone or in combination with NM21-1480, may overcome shortcomings of previous MSLN-targeted immuno-oncology drugs, exhibiting enhanced discrimination of high MSLN-expressing cell activity in the presence of sMSLN.

Synthesis, maturation, and trafficking of human Na+-dicarboxylate cotransporter NaDC1 requires the chaperone activity of cyclophilin B.

Renal excretion of citrate, an inhibitor of calcium stone formation, is controlled mainly by reabsorption via the apical Na(+)-dicarboxylate cotransporter NaDC1 (SLC13A2) in the proximal tubule. Recently, it has been shown that the protein phosphatase calcineurin inhibitors cyclosporin A (CsA) and FK-506 induce hypocitraturia, a risk factor for nephrolithiasis in kidney transplant patients, but apparently through urine acidification. This suggests that these agents up-regulate NaDC1 activity. Using the Xenopus lævis oocyte and HEK293 cell expression systems, we examined first the effect of both anti-calcineurins on NaDC1 activity and expression. While FK-506 had no effect, CsA reduced NaDC1-mediated citrate transport by lowering heterologous carrier expression (as well as endogenous carrier expression in HEK293 cells), indicating that calcineurin is not involved. Given that CsA also binds specifically to cyclophilins, we determined next whether such proteins could account for the observed changes by examining the effect of selected cyclophilin wild types and mutants on NaDC1 activity and cyclophilin-specific siRNA. Interestingly, our data show that the cyclophilin isoform B is likely responsible for down-regulation of carrier expression by CsA and that it does so via its chaperone activity on NaDC1 (by direct interaction) rather than its rotamase activity. We have thus identified for the first time a regulatory partner for NaDC1, and have gained novel mechanistic insight into the effect of CsA on renal citrate transport and kidney stone disease, as well as into the regulation of membrane transporters in general.