Mice Lacking beta2-Integrin Function Remain Glucose Tolerant in Spite of Insulin Resistance, Neutrophil Infiltration and Inflammation

Beta2-integrins are important in leukocyte trafficking and function, and are regulated through the binding of cytoplasmic proteins, such as kindlin-3, to their intracellular domain. Here, we investigate the involvement of beta2-integrins in the regulation of metabolic disease using mice where the kindlin-3 binding site in the beta2-integrin cytoplasmic tail has been mutated (TTT/AAA-beta2-integrin knock-in (KI) mice), leading to expressed but dysfunctional beta2-integrins and significant neutrophilia in vivo. Beta2-integrin KI mice fed on a high fat diet showed normal weight gain, and normal accumulation of macrophages and lymphocytes in white adipose tissue (WAT) and liver, but increased neutrophil numbers especially in WAT. In addition, beta2-integrin KI mice fed on a high fat diet showed significantly increased peripheral insulin resistance in response to high-fat feeding. However, this was associated with improved glucose disposal following glucose load. Interestingly, beta2-integrin KI neutrophils produced more elastase in vitro, in response to stimulation. Beta2-integrin KI mice displayed variability of tissue inflammatory status, with liver and WAT exhibiting little or no difference in inflammation compared to high fat fed controls, whereas skeletal muscle demonstrated a raised inflammatory profile in association with higher elastase levels and diminished signalling through the IRS1-PKB pathway. In conclusion, although expression of dysfunctional beta2-integrins increased neutrophil production and infiltration into tissue, skeletal muscle was the most affected tissue exhibiting evidence of higher neutrophil activity and insulin resistance. Thus, beta2-integrins modulate glucose homeostasis during high fat feeding predominantly through actions on skeletal muscle to affect metabolic phenotype in vivo.Peer reviewe

Targeted gene sanger sequencing should remain the first-tier genetic test for children suspected to have the five common X-linked inborn errors of immunity

DATA AVAILABILITY STATEMENT : The original contributions presented in the study are included in the article/Supplementary Material. Further inquiries can be directed to the corresponding author.To address inborn errors of immunity (IEI) which were underdiagnosed in resource-limited regions, our centre developed and offered free genetic testing for the most common IEI by Sanger sequencing (SS) since 2001. With the establishment of The Asian Primary Immunodeficiency (APID) Network in 2009, the awareness and definitive diagnosis of IEI were further improved with collaboration among centres caring for IEI patients from East and Southeast Asia. We also started to use whole exome sequencing (WES) for undiagnosed cases and further extended our collaboration with centres from South Asia and Africa. With the increased use of Next Generation Sequencing (NGS), we have shifted our diagnostic practice from SS to WES. However, SS was still one of the key diagnostic tools for IEI for the past two decades. Our centre has performed 2,024 IEI SS genetic tests, with in-house protocol designed specifically for 84 genes, in 1,376 patients with 744 identified to have disease-causing mutations (54.1%). The high diagnostic rate after just one round of targeted gene SS for each of the 5 common IEI (X-linked agammaglobulinemia (XLA) 77.4%, Wiskott–Aldrich syndrome (WAS) 69.2%, X-linked chronic granulomatous disease (XCGD) 59.5%, X-linked severe combined immunodeficiency (XSCID) 51.1%, and X-linked hyper-IgM syndrome (HIGM1) 58.1%) demonstrated targeted gene SS should remain the first-tier genetic test for the 5 common X-linked IEI.The Hong Kong Society for Relief of Disabled Children and Jeffrey Modell Foundation.http://www.frontiersin.org/Immunologyam2023Paediatrics and Child Healt

Loss of all three APP family members during development impairs synaptic function and plasticity, disrupts learning, and causes an autism-like phenotype

The key role of APP for Alzheimer pathogenesis is well established. However, perinatal lethality of germline knockout mice lacking the entire APP family has so far precluded the analysis of its physiological functions for the developing and adult brain. Here, we generated conditional APP/APLP1/APLP2 triple KO (cTKO) mice lacking the APP family in excitatory forebrain neurons from embryonic day 11.5 onwards. NexCre cTKO mice showed altered brain morphology with agenesis of the corpus callosum and disrupted hippocampal lamination. Further, NexCre cTKOs revealed reduced basal synaptic transmission and drastically reduced long-term potentiation that was associated with reduced dendritic length and reduced spine density of pyramidal cells. With regard to behavior, lack of the APP family leads not only to severe impairments in a panel of tests for learning and memory, but also to an autism-like phenotype including repetitive rearing and climbing, impaired social communication, and deficits in social interaction. Together, our study identifies essential functions of the APP family during development, for normal hippocampal function and circuits important for learning and social behavior

Loss of all three APP family members during development impairs synaptic function and plasticity, disrupts learning, and causes an autism-like phenotype

The key role of APP for Alzheimer pathogenesis is well established. However, perinatal lethality of germline knockout mice lacking the entire APP family has so far precluded the analysis of its physiological functions for the developing and adult brain. Here, we generated conditional APP/APLP1/APLP2 triple KO (cTKO) mice lacking the APP family in excitatory forebrain neurons from embryonic day 11.5 onwards. NexCre cTKO mice showed altered brain morphology with agenesis of the corpus callosum and disrupted hippocampal lamination. Further, NexCre cTKOs revealed reduced basal synaptic transmission and drastically reduced long-term potentiation that was associated with reduced dendritic length and reduced spine density of pyramidal cells. With regard to behavior, lack of the APP family leads not only to severe impairments in a panel of tests for learning and memory, but also to an autism-like phenotype including repetitive rearing and climbing, impaired social communication, and deficits in social interaction. Together, our study identifies essential functions of the APP family during development, for normal hippocampal function and circuits important for learning and social behavior.ISSN:0261-4189ISSN:1460-207

NINJ1 mediates plasma membrane rupture during lytic cell death

Plasma membrane rupture (PMR) is the final cataclysmic event in lytic cell death. PMR releases intracellular molecules known as damage-associated molecular patterns (DAMPs) that propagate the inflammatory response1–3. The underlying mechanism of PMR, however, is unknown. Here we show that the cell-surface NINJ1 protein4–8, which contains two transmembrane regions, has an essential role in the induction of PMR. A forward-genetic screen of randomly mutagenized mice linked NINJ1 to PMR. Ninj1−/− macrophages exhibited impaired PMR in response to diverse inducers of pyroptotic, necrotic and apoptotic cell death, and were unable to release numerous intracellular proteins including HMGB1 (a known DAMP) and LDH (a standard measure of PMR). Ninj1–/– macrophages died, but with a distinctive and persistent ballooned morphology, attributable to defective disintegration of bubble-like herniations. Ninj1–/– mice were more susceptible than wild-type mice to infection with Citrobacter rodentium, which suggests a role for PMR in anti-bacterial host defence. Mechanistically, NINJ1 used an evolutionarily conserved extracellular domain for oligomerization and subsequent PMR. The discovery of NINJ1 as a mediator of PMR overturns the long-held idea that cell death-related PMR is a passive event

Improved Size-Tunable Synthesis of Monodisperse Gold Nanorods through the Use of Aromatic Additives

We report an improved synthesis of colloidal gold nanorods (NRs) by using aromatic additives that reduce the concentration of hexadecyltrimethylammonium bromide surfactant to ∼0.05 M as opposed to 0.1 M in well-established protocols. The method optimizes the synthesis for each of the 11 additives studied, allowing a rich array of monodisperse gold NRs with longitudinal surface plasmon resonance tunable from 627 to 1246 nm to be generated. The gold NRs form large-area ordered assemblies upon slow evaporation of NR solution, exhibiting liquid crystalline ordering and several distinct local packing motifs that are dependent upon the NR’s aspect ratio. Tailored synthesis of gold NRs with simultaneous improvements in monodispersity and dimensional tunability through rational introduction of additives will not only help to better understand the mechanism of seed-mediated growth of gold NRs but also advance the research on plasmonic metamaterials incorporating anisotropic metal nanostructures