Microglia complement signaling promotes neuronal elimination and normal brain functional connectivity.

Complement signaling is thought to serve as an opsonization signal to promote the phagocytosis of synapses by microglia. However, while its role in synaptic remodeling has been demonstrated in the retino-thalamic system, it remains unclear whether complement signaling mediates synaptic pruning in the brain more generally. Here we found that mice lacking the Complement receptor 3, the major microglia complement receptor, failed to show a deficit in either synaptic pruning or axon elimination in the developing mouse cortex. Instead, mice lacking Complement receptor 3 exhibited a deficit in the perinatal elimination of neurons in the cortex, a deficit that is associated with increased cortical thickness and enhanced functional connectivity in these regions in adulthood. These data demonstrate a role for complement in promoting neuronal elimination in the developing cortex.

Refeeding Syndrome in Pediatric Age, An Unknown Disease: A Narrative Review.

Refeeding syndrome (RS) is characterized by electrolyte imbalances that can occur in malnourished and abruptly refed patients. Typical features of RS are hypophosphatemia, hypokalemia, hypomagnesemia, and thiamine deficiency. It is a potentially life-threatening condition that can affect both adults and children, although there is scarce evidence in the pediatric literature. The sudden increase in food intake causes a shift in the body's metabolism and electrolyte balance, leading to symptoms such as weakness, seizures, and even heart failure. A proper management with progressive increase in nutrients is essential to prevent the onset of this condition and ensure the best possible outcomes. Moreover, an estimated incidence of up to 7.4% has been observed in pediatric intensive care unit patients receiving nutritional support, alone or as an adjunct. To prevent RS, it is important to carefully monitor feeding resumption, particularly in severely malnourished individuals. A proper strategy should start with small amounts of low-calorie fluids and gradually increasing the calorie content and amount of food over several days. Close monitoring of electrolyte levels is critical and prophylactic use of dietary supplements such as thiamine may be required to correct any imbalances that may occur. In this narrative review, we aim to provide a comprehensive understanding of RS in pediatric clinical practice and provide a possible management algorithm.

Neurological impairment and malnutrition in children: The role of home enteral nutrition in real life.

Objective: Recent decades have brought an increased survival of children with Neurologic Impairment (NI) but malnutrition and digestive comorbidity remain important challenges to face. We designed the present study to assess the course of nutritional status following standardized Home Enteral Nutrition (HEN) program and to evaluate impact of changing mode of feeding, as a part of overall multidisciplinary management, on digestive co-morbidity as Gastro-Esophageal Reflux Disease (GERD), Oropharyngeal Dysphagia (OPD), constipation and airway aspiration. Methods: We performed a retrospective analysis on NI children entered into Institutional HEN program due to NI disorders between January 2011 and 2019. Demographic, anthropometric characteristics (BMI z-score and weight for age z-score) and symptoms (GERD, OPD constipation and airway aspiration) were collected at the enrolment and during the follow up. Results: We enrolled 402 patients (median age: 39 months); overall survival was 97%. Nutritional status was significantly improved by HEN; in particular growth profile significantly changed within the first 2 years following HEN beginning; GERD and airways aspirations decreased after HEN beginning. Constipation and OPD remained unchanged over time. Conclusions: Malnutrition and digestive complaints are distinctive features of NI children. Nutritional status improve after 2 years from the beginning of standardized nutritional interventions. Overall multidisciplinary care, including standardized HEN protocols, seems to also impact on GERD and airway aspirations, which can decrease over time. It is possible that constipation and OPD, unchanged over time, are more dependent on underlying diseases than on overall treatments.

Enteral formula compared to Nissen-Fundoplication: Data from a retrospective analysis on tolerance, utility, applicability, and safeness in children with neurological diseases.

Objectives and study: Approximately 46-90% of children with neurological disorders (NDs) suffer from gastrointestinal diseases, such as gastro-esophageal reflux disease (GERD), constipation, or malnutrition. Therefore, enteral feeding is often necessary to achieve nutritional requirements. The treatment of GERD could be based on pharmacological therapy, nutritional treatment (changing the type of formula), or surgical treatment (Nissen Fundoplication, NF). The aim of this study was to describe and compare resource consumption between NE based on different formulas and NF in patients with ND. Methods: We performed a retrospective analysis on all children with neurological damage (age: 29 days-17 years) treated from January 2009 to January 2019 due to nutritional problems and food and/or gastrointestinal intolerances. For all patients, demographic and anthropometric characteristics, symptoms, type of nutrition (formula and enteral access), and number and type of outpatient or emergency room visits were collected. Patients with <24 months of age at the closing of the database and with <24 months of follow-up were excluded. Results: Out of 376 children, 309 children (M: 158; median age: 4 IQR 1-10) were enrolled, among which, 65 patients (NF group M: 33; median age: 5.3 IQR 1.8-10.7) underwent NF. Vomit, GERD, and dysphagia were more represented in the NF group (p < 0.05). Our analysis shows that the NF group seems to present a lower number of hospitalization and a lower number of visits for non-GI disorders, but a higher number of visits for GI disorders compared to non-NF. In the NF group, a higher prevalence of the use of amino-acid-based formula and free diet is observed, with a trend for the lower prevalence of casein-based or whey+casein-based formula (Fisher test p = 0.072). The median cost of a patient enrolled in the database is € 19,515 ± 540 ($ 20,742.32 ± 573.96) per year, with no significant difference between the two groups. Regarding formula, at baseline, 76 children consumed a free diet, 24 a casein-based formula, 139 a whey+casein-based formula, 46 a whey-based formula, and 24 an amino-acid-based formula. Conclusions: In conclusion, compared to EN, NF may not improve the clinical aspect and related costs in children with NDs. Considering the psychological and QoL burden for patients, in a "step-up" strategy, EN could be proposed as an efficient alternative to NF.

Five-Year Inpatient Management of Teenagers With Anorexia Nervosa: Focus on Nutritional Issues.

OBJECTIVES: In patients with Anorexia Nervosa (AN) malnutrition can lead to life-long nutritional treatments. The refeeding process can combine natural feeding (NF) with specific nutritional strategies, including oral nutritional supplements (ONS) and nasogastric feeding (NGF). Aims of the present study were to assess the efficacy of hospital protocol and identify the most effective inpatient nutritional strategies for weight restoration. METHODS: All patients hospitalized from April 2015 to April 2020 were enrolled. According to hospital protocol, NF was proposed to all patients; ONS were combined with NF if caloric intake was <70% of the requirements and NGF was added if caloric intake did not reach 30% in the first week from admission. RESULTS: Overall, 186 patients [M = 20; median age 14 (interquartile range 1316)] were included. Nutritional issues were the main indication to admission (56.6%). A significant effect of combination treatment, with a shorter duration of hospitalization when using ONS with NGF in addition to NF was found (ß: -20.28 [95% confidence interval -34.92:-5.65], P  < 0.001). Only one patient showed a significant but limited increase of liver enzymes. CONCLUSIONS: We provide a safe and effective standardized protocol to treat the malnutrition of teenagers with AN in an inpatient setting. Malnutrition was the most important cause of admission, and more than half of the patients admitted were severely malnourished. The combination of NF, ONS, and NGF was the most effective strategy to achieve the weight restoration; however, this result should be validated on larger series of patients treated with NGF and NF.

Anti-Tumor Necrosis Factor-Alpha Withdrawal in Children With Inflammatory Bowel Disease in Endoscopic and Histologic Remission.

BACKGROUND: The aim of the present study was to investigate outcomes of anti-TNF-alpha (ATA) withdrawal in selected pediatric patients with inflammatory bowel disease who achieved clinical remission and mucosal and histological healing (MH and HH). METHODS: A retrospective analysis was performed on children and adolescents affected by Crohn disease (CD) and ulcerative colitis (UC) who were followed up at 2 tertiary referral centers from 2008 through 2018. The main outcome measure was clinical relapse rates after ATA withdrawal. RESULTS: One hundred seventy patients received scheduled ATA treatment; 78 patients with CD and 56 patients with UC underwent endoscopic reassessment. We found that MH was achieved by 32 patients with CD (41%) and 30 patients with UC (53.6%); 26 patients with CD (33.3%) and 22 patients with UC (39.3%) achieved HH. The ATA treatment was suspended in 45 patients, 24 affected by CD and 21 by UC, who all achieved concurrently complete MH (Simplified Endoscopic Score for CD, 0; Mayo score, 0, respectively) and HH. All the patients who suspended ATA shifted to an immunomodulatory agent or mesalazine. In contrast, 17 patients, 8 with CD and 9 with UC, continued ATA because of growth needs, the persistence of slight endoscopic lesions, and/or microscopic inflammation. Thirteen out of 24 patients with CD who suspended ATA experienced disease relapse after a median follow-up time of 29 months, whereas no recurrence was observed among the 9 patients with CD who continued treatment (P = 0.05). Among the patients with UC, there were no significant differences in relapse-free survival among those who discontinued ATA and those who did not suspend treatment (P = 0.718). CONCLUSIONS: Despite the application of rigid selection criteria, ATA cessation remains inadvisable in CD. In contrast, in UC, the concurrent achievement of MH and HH may represent promising selection criteria to identify patients in whom treatment withdrawal is feasible.

Long-term outcome of pancreatic function following oncological surgery in children: Institutional experience and review of the literature.

BACKGROUND: Pancreatic neoplasms are uncommon in children and in most cases they are benign or have low malignant potential. Pancreatoblastoma and solid pseudopapillary tumor are the most frequent types in early and late childhood, respectively. Complete resection, although burdened by severe complications, is the only curative treatment for these diseases. Pancreatic surgery may result in impaired exocrine and endocrine pancreatic function. However, limited data are available on the long-term pediatric pancreatic function following surgical resection. AIM: To investigate endocrine and exocrine pancreatic function and growth after oncological pancreatic surgery in a pediatric series. METHODS: A retrospective analysis of all pediatric patients who underwent surgery for pancreatic neoplasm in our Institution from January 31, 2002 to the present was performed. Endocrine and exocrine insufficiency, auxological and fat-soluble vitamin status (A, D, E and clotting tests) were assessed at diagnosis and at every follow-up visit. Exocrine insufficiency was defined as steatorrhea with fecal elastase-1 < 200 µg/g stool, while endocrine insufficiency was identified as onset of Diabetes or Impaired Glucose Tolerance. Growth was evaluated based on body mass index (BMI) z-score trend. RESULTS: Sixteen patients (12 girls and 4 boys, mean age 10.7 ± 5.3 years), were included. Nine patients (56%) had a neoplasm in the pancreatic head, 4 in the body/tail, 2 in the tail and 1 in the body. Histological findings were as follows: Solid pseudopapillary tumor in 10 patients (62.5%), insulinoma in 2 patients, neuroendocrine tumor in 2 patients and acinar cell carcinoma in 2 patients. The most frequent surgery was pancreaticoduodenectomy (50%). Exocrine failure occurred in 4 patients (25%) and endocrine failure in 2 patients (12.5%). Exocrine insufficiency occurred early (within 6 mo after surgery) and endocrine insufficiency later (8 and 10 years after surgery). Mean BMI z-score was 0.36 ± 1.1 at diagnosis and 0.27 ± 0.95 at the last assessment. Vitamin D was insufficient (< 30 ng/mL) in 8 of the 16 patients during the follow-up period. Vitamins A, E and clotting test were into the normal ranges in all patients. CONCLUSION: Careful and long-term monitoring should follow any pancreatic surgery, to recognize and promptly treat exocrine and endocrine pancreatic insufficiency, which can occur after surgery.

Etiology and Management of Pediatric Intestinal Failure: Focus on the Non-Digestive Causes.

BACKGROUND: Intestinal failure (IF) is defined as reduction in functioning gut mass below the minimal amount necessary for adequate digestion and absorption. In most cases, IF results from intrinsic diseases of the gastrointestinal tract (digestive IF) (DIF); few cases arise from digestive vascular components, gut annexed (liver and pancreas) and extra-digestive organs or from systemic diseases (non-digestive IF) (NDIF). The present review revised etiology and treatments of DIF and NDIF, with special focus on the pathophysiological mechanisms, whereby NDIF develops. METHODS: We performed a comprehensive search of published literature from January 2010 to the present by selecting the following search strings: "intestinal failure" OR "home parenteral nutrition" OR "short bowel syndrome" OR "chronic pseudo-obstruction" OR "chronic intestinal pseudo-obstruction" OR "autoimmune enteropathy" OR "long-term parenteral nutrition". RESULTS: We collected overall 1656 patients with well-documented etiology of IF: 1419 with DIF (86%) and 237 with NDIF (14%), 55% males and 45% females. Among DIF cases, 66% had SBS and among NDIF cases 90% had malabsorption/maldigestion. CONCLUSIONS: The improved availability of diagnostic and therapeutic tools has increased prevalence and life expectancy of rare and severe diseases responsible for IF. The present review greatly expands the spectrum of knowledge on the pathophysiological mechanisms through which the diseases not strictly affecting the intestine can cause IF. In view of the rarity of the majority of pediatric IF diseases, the development of IF Registries is strongly required; in fact, through information flow within the network, the Registries could improve IF knowledge and management.

Mucosal and Histologic Healing in Children With Inflammatory Bowel Disease Treated With Antitumor Necrosis Factor-Alpha.

OBJECTIVES: Mucosal healing (MH) and histological healing (HH) have been recently proposed as a novel treatment target for inflammatory bowel disease (IBD). The aim of the present study was to evaluate real-life achievement of such outcomes in a cohort of pediatric patients with IBD treated with anti-TNF-alpha (ATA) agents. METHODS: A retrospective analysis was performed on patients affected by IBD who received ATA and were followed up at two referral centers. Incidence and cumulative rates for MH and HH for each group were calculated. RESULTS: Of 170 (105 Crohn's disease [CD] and 65 ulcerative colitis [UC]) patients, 78 with CD and 56 with UC underwent endoscopic re-assessment during the study period. MH was achieved by 32 CD (41%) and 30 UC (53.6%) patients; 26 CD (33.3%) and 22 UC (39.3%) patients achieved HH. MH incidence rate was 19.1/1000 and 47/1000 person-months, whereas HH incidence rate was 15.5/1000 and 34.7/1000 person-months for CD and UC, respectively. Remission at the end of induction was associated with higher MH and HH rates (HR: 2.43, P = 0.049 and HR: 2.94, P = 0.046, respectively) in CD. In UC, adalimumab was associated with lower MH and HH rates (HR: 0.16, P = 0.004 and HR: 0.07, P = 0.003). CONCLUSIONS: We reported a real-life experience arising from a large cohort of pediatric IBD who received ATA scheduled treatment. Less than half of patients with CD and only a little >50% of UC patients achieved MH. Microscopical inflammation was observed in 18.8% CD and 26.7% UC patients who achieved MH. Overall, MH and HH rates appear lower compared to previously published data.

Gpr37l1/prosaposin receptor regulates Ptch1 trafficking, Shh production, and cell proliferation in cerebellar primary astrocytes.

Mammalian cerebellar astrocytes critically regulate the differentiation and maturation of neuronal Purkinje cells and granule precursors. The G protein-coupled receptor 37-like 1 (Gpr37l1) is expressed by Bergmann astrocytes and interacts with patched 1 (Ptch1) at peri-ciliary membranes. Cerebellar primary astrocyte cultures from wild-type and Gpr37l1 null mutant mouse pups were established and studied. Primary cilia were produced by cultures of both genotypes, as well as Ptch1 and smoothened (Smo) components of the sonic hedgehog (Shh) mitogenic pathway. Compared to wild-type cells, Gpr37l1-/- astrocytes displayed striking increases in proliferative activity, Ptch1 protein expression and internalization, intracellular cholesterol content, ciliary localization of Smo, as well as a marked production of active Shh. Similar effects were reproduced by treating wild-type astrocytes with a putative prosaptide ligand of Gpr37l1. These findings indicate that Gpr37l1-Ptch1 interactions specifically regulate Ptch1 internalization and trafficking, with consequent stimulation of Shh production and activation of proliferative signaling.

Circulating miRNAs in Small Extracellular Vesicles Secreted by a Human Melanoma Xenograft in Mouse Brains.

The identification of liquid biomarkers remains a major challenge to improve the diagnosis of melanoma patients with brain metastases. Circulating miRNAs packaged into tumor-secreted small extracellular vesicles (sEVs) contribute to tumor progression. To investigate the release of tumor-secreted miRNAs by brain metastasis, we developed a xenograft model where human metastatic melanoma cells were injected intracranially in nude mice. The comprehensive profiles of both free miRNAs and those packaged in sEVs secreted by the melanoma cells in the plasma demonstrated that most (80%) of the sEV-associated miRNAs were also present in serum EVs from a cohort of metastatic melanomas, included in a publicly available dataset. Remarkably, among them, we found three miRNAs (miR-224-5p, miR-130a-3p and miR-21-5p) in sEVs showing a trend of upregulation during melanoma progression. Our model is proven to be valuable for identifying miRNAs in EVs that are unequivocally secreted by melanoma cells in the brain and could be associated to disease progression.

Adherence to Gluten-free Diet in a Celiac Pediatric Population Referred to the General Pediatrician After Remission.

OBJECTIVES: Assessment of adherence to gluten-free diet in celiac disease (CD) is generally recommended. Few data are available about consequences of transition from the referral center to the general pediatrician (GP) once remission is achieved. METHODS: Adherence was assessed in patients referred to the GP for an annual basis follow-up, called back for re-evaluation. Immunoglobulin A (IgA) antitissue transglutaminase (anti-tTG) antibodies and the Biagi score (BS) were determined at last follow-up at the referral center (V1), and at re-evaluation (V2). Patients were classified as adherent (BS 3-4, IgA anti-tTG <7 U/mL) and nonadherent (BS 0-2, IgA anti-tTG ≥7). Scores of adherence were correlated with personal and clinical data. RESULTS: We evaluated 200 patients. Overall, we found good adherence rates in 94.95% of patients at V1 and 83.5% at V2. IgA anti-tTG were negative in 100% at V1 and 96.97% at V2. BS is 3 to 4 in 94.5% at V1 and 84% at V2. Adherence at V2 was significantly worse than V1 (P < 0.001). No significant associations were found between scores of adherence and sex, symptoms and age at diagnosis, family history of CD, comorbidity, and diagnosis by endoscopy. Age 13 years or older represents a risk factor for lack of compliance at V1 (P = 0.02) and V2 (P = 0.04), and foreign nationality at V2 (P = 0.001). CONCLUSIONS: The BS, serology, and a clinical interview, integrated, are reliable tools for assessing pediatric adherence to gluten-free diet. We argue that referring patients to the GP after remission of CD is important, but the process must be improved and recommendations are required.

Brain Invasion along Perivascular Spaces by Glioma Cells: Relationship with Blood-Brain Barrier.

The question whether perivascular glioma cells invading the brain far from the tumor bulk may disrupt the blood-brain barrier (BBB) represents a crucial issue because under this condition tumor cells would be no more protected from the reach of chemotherapeutic drugs. A recent in vivo study that used human xenolines, demonstrated that single glioma cells migrating away from the tumor bulk are sufficient to breach the BBB. Here, we used brain xenografts of patient-derived glioma stem-like cells (GSCs) to show by immunostaining that in spite of massive perivascular invasion, BBB integrity was preserved in the majority of vessels located outside the tumor bulk. Interestingly, the tumor cells that invaded the brain for the longest distances traveled along vessels with retained BBB integrity. In surgical specimens of malignant glioma, the area of brain invasion showed several vessels with preserved BBB that were surrounded by tumor cells. On transmission electron microscopy, the cell inter-junctions and basal lamina of the brain endothelium were preserved even in conditions in which the tumor cells lay adjacently to blood vessels. In conclusion, BBB integrity associates with extensive perivascular invasion of glioma cells.

Gluten Deprivation: What Nutritional Changes Are Found During the First Year in Newly Diagnosed Coeliac Children?

AIM: A gluten-free diet (GFD) can expose children to excessive calories and fat intake. The study is intended to verify whether and how food intake, laboratory parameters, and growth are modified by a year of GFD. METHODS: In 79 CD (coeliac disease) children (mean age 7.9 ± 3.8 years, 52 females, 27 males) diagnosed over 24 months, 24-h food diaries, food-frequency patterns, anthropometric and laboratory parameters (mainly blood sugar, insulin, lipid profile, and homocysteine) were prospectively collected before and during the first year of GFD. Nutrient intakes were compared over time and with recommendations. They were also used as regressors to explain the levels and changes of metabolic and growth variables. p-values < 0.05 were considered statistically significant. RESULTS: Average macronutrient intake did not change during the year. Caloric intake remained below 90% (p ≤ 0.0001) and protein intake above 200% (p ≤ 0.0001) of recommendations. Lipid intake was stable at 34% of overall energy intake. Unsaturated fats increased (less omega-6 and more omega-3 with a ratio improvement from 13.3 ± 5.5 to 8.8 ± 3.1) and so did fibers, while folate decreased. The children who experienced a containment in their caloric intake during the year, presented a slower catch-up growth. Some differences were found across gender and age groups. In particular, adolescents consumed less calories, and females more omega-3. Fiber and simple sugar intakes emerged as implicated in lipid profile shift: fibers negatively with triglycerides (TG) (p = 0.033), simple sugars negatively with high-density lipoprotein (HDL) (p = 0.056) and positively with TG (p = 0.004). Waist-to-height ratio was positively associated with homocysteine (p = 0.018) and Homeostasis Model Assessment (p = 0.001), negatively with fibers (p = 0.004). CONCLUSION: In the short run, GFD is nutritionally very similar to any diet with gluten, with some improvements in unsaturated fats and fiber intake. Along with simple sugars containment, this may offer CD patients the opportunity for a fresh start. Caloric intakes may shift and should be monitored, especially in adolescents.

Correction to: The Medial Septum Is Insulin Resistant in the AD Presymptomatic Phase: Rescue by Nerve Growth Factor-Driven IRS1 Activation.

The authors, due to the change in one of the University name at the affiliation, hereby correct the proof.

Atrophy, oxidative switching and ultrastructural defects in skeletal muscle of the ataxia telangiectasia mouse model.

Ataxia telangiectasia is a rare, multi system disease caused by ATM kinase deficiency. Atm-knockout mice recapitulate premature aging, immunodeficiency, cancer predisposition, growth retardation and motor defects, but not cerebellar neurodegeneration and ataxia. We explored whether Atm loss is responsible for skeletal muscle defects by investigating myofiber morphology, oxidative/glycolytic activity, myocyte ultrastructural architecture and neuromuscular junctions. Atm-knockout mice showed reduced muscle and fiber size. Atrophy, protein synthesis impairment and a switch from glycolytic to oxidative fibers were detected, along with an increase of in expression of slow and fast myosin types (Myh7, and Myh2 and Myh4, respectively) in tibialis anterior and solei muscles isolated from Atm-knockout mice. Transmission electron microscopy of tibialis anterior revealed misalignments of Z-lines and sarcomeres and mitochondria abnormalities that were associated with an increase in reactive oxygen species. Moreover, neuromuscular junctions appeared larger and more complex than those in Atm wild-type mice, but with preserved presynaptic terminals. In conclusion, we report for the first time that Atm-knockout mice have clear morphological skeletal muscle defects that will be relevant for the investigation of the oxidative stress response, motor alteration and the interplay with peripheral nervous system in ataxia telangiectasia.

The Medial Septum Is Insulin Resistant in the AD Presymptomatic Phase: Rescue by Nerve Growth Factor-Driven IRS1 Activation.

Basal forebrain cholinergic neurons (BFCN) are key modulators of learning and memory and are high energy-demanding neurons. Impaired neuronal metabolism and reduced insulin signaling, known as insulin resistance, has been reported in the early phase of Alzheimer's disease (AD), which has been suggested to be "Type 3 Diabetes." We hypothesized that BFCN may develop insulin resistance and their consequent failure represents one of the earliest event in AD. We found that a condition reminiscent of insulin resistance occurs in the medial septum of 3 months old 3×Tg-AD mice, reported to develop typical AD histopathology and cognitive deficits in adulthood. Further, we obtained insulin resistant BFCN by culturing them with high insulin concentrations. By means of these paradigms, we observed that nerve growth factor (NGF) reduces insulin resistance in vitro and in vivo. NGF activates the insulin receptor substrate 1 (IRS1) and rescues c-Fos expression and glucose metabolism. This effect involves binding of activated IRS1 to the NGF receptor TrkA, and is lost in presence of the specific IRS inhibitor NT157. Overall, our findings indicate that, in a well-established animal model of AD, the medial septum develops insulin resistance several months before it is detectable in the neocortex and hippocampus. Remarkably, NGF counteracts molecular alterations downstream of insulin-resistant receptor and its nasal administration restores insulin signaling in 3×Tg-AD mice by TrkA/IRS1 activation. The cross-talk between NGF and insulin pathways downstream the insulin receptor suggests novel potential therapeutic targets to slow cognitive decline in AD and diabetes-related brain insulin resistance.

CASP4 gene silencing in epithelial cancer cells leads to impairment of cell migration, cell-matrix adhesion and tissue invasion.

Inflammatory caspases, including human caspase-4 (CASP4), play key roles in innate immune responses to promote fusion of phagosomes harboring pathogenic bacteria with lysosomes, halt intracellular replication of pathogens, maturation and secretion of pro-inflammatory cytokines. The role of inflammatory caspases in cancer cells remains poorly investigated. Here, we explored the consequences of modulating CASP4 expression levels on the migratory behavior of epithelial cancer cell lines. By a gene silencing approach and in vitro and in vivo studies we show that down-regulation of CASP4 leads to impaired cell migration and cell-matrix adhesion. This phenotype is accompanied by an increased actin cytoskeleton polymerization, changes in the overall organization of adherens junctions (AJs) and number and size of focal adhesions. Interestingly, the cell migration deficit could be reversed by epithelial growth factor treatment, and depletion of calcium ions unveiled a role of CASP4 in the novo assembly of AJs, suggesting that the role of CASP4 is not cell-autonomous. Finally, CASP4-silenced A431 cells exhibited a severe reduction in their ability to invade lung tissue, when injected into nude mice. Overall, our data support the emerging evidence that inflammatory caspases can regulate cell migration through actin remodeling and uncover a novel role of CASP4 in cancer cell behavior.

Microglia remodel synapses by presynaptic trogocytosis and spine head filopodia induction.

Microglia are highly motile glial cells that are proposed to mediate synaptic pruning during neuronal circuit formation. Disruption of signaling between microglia and neurons leads to an excess of immature synaptic connections, thought to be the result of impaired phagocytosis of synapses by microglia. However, until now the direct phagocytosis of synapses by microglia has not been reported and fundamental questions remain about the precise synaptic structures and phagocytic mechanisms involved. Here we used light sheet fluorescence microscopy to follow microglia-synapse interactions in developing organotypic hippocampal cultures, complemented by a 3D ultrastructural characterization using correlative light and electron microscopy (CLEM). Our findings define a set of dynamic microglia-synapse interactions, including the selective partial phagocytosis, or trogocytosis (trogo-: nibble), of presynaptic structures and the induction of postsynaptic spine head filopodia by microglia. These findings allow us to propose a mechanism for the facilitatory role of microglia in synaptic circuit remodeling and maturation.