FcγRI-Deficient Mice Show Multiple Alterations to Inflammatory and Immune Responses

AbstractThe inactivation of the mouse high-affinity IgG Fc receptor FcγRI resulted in a wide range of defects in antibody Fc-dependent functions. These studies showed the primary importance of FcγRI in endocytosis of monomeric IgG, kinetics, and extent of phagocytosis of immune complexes, in macrophage-based ADCC, and in immune complex-dependent antigen presentation to primed T cells. In the absence of FcγRI, antibody responses were elevated, implying the removal of a control point by the deletion of FcγRI. In addition, FcR-γ chain-deficient mice were found to express partially functional FcγRI. Thus, FcγRI is an early participant in Fc-dependent cell activation and in the development of immune responses

Optimised human stool sample collection for multi-omic microbiota analysis

To accurately define the role of the gut microbiota in health and disease pathogenesis, the preservation of stool sample integrity, in terms of microbial community composition and metabolic function, is critical. This presents a challenge for any studies which rely on participants self-collecting and returning stool samples as this introduces variability and uncertainty of sample storage/handling. Here, we tested the performance of three stool sample collection/preservation buffers when storing human stool samples at different temperatures (room temperature [20 °C], 4 °C and – 80 °C) for up to three days. We compared and quantified differences in 16S rRNA sequencing composition and short-chain fatty acid profiles compared against immediately snap-frozen stool. We found that the choice of preservation buffer had the largest effect on the resulting microbial community and metabolomic profiles. Collectively analysis confirmed that PSP and RNAlater buffered samples most closely recapitulated the microbial diversity profile of the original (immediately – 80 °C frozen) sample and should be prioritised for human stool microbiome studie

The Role of Dectin-2 for Host Defense Against Disseminated Candidiasis

Acknowledgments This work was supported by European Union ALLFUN (FP7/2007 2013, HEALTH-2010-260338) (Fungi in the setting of inflammation, allergy and autoimmune diseases: Translating basic science into clinical practices ‘‘ALLFUN’’) to D.C.I., F.C., C.F., M.G.N., and N.A.R.G. M.G.N and J.Q. were supported by a Vici grant of The Netherlands Organization of Scientific Research (to M.G.N.). M.G.N. was supported by an ERC Consolidator Grant (nr. 310372). N.A.R.G. was also supported by the Wellcome Trust (086827, 075470, 097377, & 101873).Peer reviewedPublisher PD

Analysis of a wild mouse promoter variant reveals a novel role for FcγRIIb in the control of the germinal center and autoimmunity.

Genetic variants of the inhibitory Fc receptor FcγRIIb have been associated with systemic lupus erythematosus in humans and mice. The mechanism by which Fcgr2b variants contribute to the development of autoimmunity is unknown and was investigated by knocking in the most commonly conserved wild mouse Fcgr2b promoter haplotype, also associated with autoimmune-prone mouse strains, into the C57BL/6 background. We found that in the absence of an AP-1-binding site in its promoter, FcγRIIb failed to be up-regulated on activated and germinal center (GC) B cells. This resulted in enhanced GC responses, increased affinity maturation, and autoantibody production. Accordingly, in the absence of FcγRIIb activation-induced up-regulation, mice developed more severe collagen-induced arthritis and spontaneous glomerular immune complex deposition. Our data highlight how natural variation in Fcgr2b drives the development of autoimmune disease. They also show how the study of such variants using a knockin approach can provide insight into immune mechanisms not possible using conventional genetic manipulation, in this case demonstrating an unexpected critical role for the activation-induced up-regulation of FcγRIIb in controlling affinity maturation, autoantibody production, and autoimmunity

Use of polyethylene naphthalate as a self-vetoing structural material

The discovery of scintillation in the blue regime from polyethylene naphthalate (PEN), a commonly used high-performance industrial polyester plastic, has sparked considerable interest from the physics community as a new type of plastic scintillator material. This observation in addition to its good mechanical and radiopurity properties makes PEN an attractive candidate as an active structure scintillator for low-background physics experiments. This paper reports on investigations of its potential in terms of production tests of custom made tiles and various scintillation light output measurements. These investigations substantiate the high potential of usage of PEN in low-background experiments

Role of the polymeric Ig receptor in mucosal B cell homeostasis

C1 - Journal Articles RefereedSecretory IgA (SIgA) is the most characteristic component of the mucosal immune system and has long been considered the major protective factor that prevents pathogens from invading hosts through the mucosae. Recent studies, however, have suggested that complete immunity against a range of mucosal bacterial and viral pathogens can be achieved in the absence of IgA. Therefore, to further dissect the role of SIgA, we generated mice deficient in the polymeric Ig receptor (pIgR(-/-) mice). As a result of an inability to transport dimeric IgA to the secretions, pIgR(-/-) mice are deficient in SIgA and accumulate circulating dimeric IgA, with serum levels 100-fold greater than those observed in normal mice. Examination of lamina propria mononuclear cells showed that pIgR(-/-) mice had approximately 3 times as many IgA-secreting cells as C57BL/6 mice. Further analysis showed that these cells displayed the differentiated IgA(+) B220(-) phenotype and accounted for a 2-fold increase in the number of lamina propria blast cells in the pIgR(-/-) mice. Subsequent experiments showed that OVA-specific CD4(+) T cell expansion following OVA feeding was not elevated in pIgR(-/-) mice. Furthermore, no differences in CD8(+) T cell tolerance or induction of influenza virus-specific CD8(+) T cells were detected in pIgR(-/-) mice compared with controls. Therefore, while SIgA is clearly involved in maintaining some parameters of mucosal homeostasis in the intestine, the mechanisms associated with its barrier function and the clinical consequences of its deficiency are yet to be identified

The Murine Stanniocalcin 1 Gene Is Not Essential for Growth and Development

The stanniocalcin 1 (STC1) gene is expressed in a wide variety of tissues, including the kidney, prostate, thyroid, bone, and ovary. STC1 protein is considered to have roles in many physiological processes, including bone development, reproduction, wound healing, angiogenesis, and modulation of inflammatory response. In fish, STC1 is a hormone that is secreted by the corpuscles of Stannius and is involved in calcium and phosphate homeostasis. To determine the role of STC1 in mammals, we generated Stc1-null mice by gene targeting. The number of Stc1(−)(/)(−) mice obtained was in accordance with Mendelian ratios, and both males and females produced offspring normally. No anatomical or histological abnormalities were detected in any tissues. Our results demonstrated that Stc1 function is not essential for growth or reproduction in the mouse

Modeling the ferrochelatase c.315-48C modifier mutation for erythropoietic protoporphyria (EPP) in mice

Erythropoietic protoporphyria (EPP) is caused by deficiency of ferrochelatase (FECH), which incorporates iron into protoporphyrin IX (PPIX) to form heme. Excitation of accumulated PPIX by light generates oxygen radicals that evoke excessive pain and, after longer light exposure, cause ulcerations in exposed skin areas of individuals with EPP. Moreover, ∼5% of the patients develop a liver dysfunction as a result of PPIX accumulation. Most patients (∼97%) have a severe FECH mutation (Mut) in trans to an intronic polymorphism (c.315-48C), which reduces ferrochelatase synthesis by stimulating the use of an aberrant 3' splice site 63 nt upstream of the normal site for exon 4. In contrast, with the predominant c.315-48T allele, the correct splice site is mostly used, and individuals with a T/Mut genotype do not develop EPP symptoms. Thus, the C allele is a potential target for therapeutic approaches that modify this splicing decision. To provide a model for pre-clinical studies of such approaches, we engineered a mouse containing a partly humanized Fech gene with the c.315-48C polymorphism. F1 hybrids obtained by crossing these mice with another inbred line carrying a severe Fech mutation (named m1Pas) show a very strong EPP phenotype that includes elevated PPIX in the blood, enlargement of liver and spleen, anemia, as well as strong pain reactions and skin lesions after a short period of light exposure. In addition to the expected use of the aberrant splice site, the mice also show a strong skipping of the partly humanized exon 3. This will limit the use of this model for certain applications and illustrates that engineering of a hybrid gene may have unforeseeable consequences on its splicing

Defective lysosome reformation during autophagy causes skeletal muscle disease.

The regulation of autophagy-dependent lysosome homeostasis in vivo is unclear. We showed that the inositol polyphosphate 5-phosphatase INPP5K regulates autophagic lysosome reformation (ALR), a lysosome recycling pathway, in muscle. INPP5K hydrolyzes phosphatidylinositol-4,5-bisphosphate [PI(4,5)P2] to phosphatidylinositol 4-phosphate [PI(4)P], and INPP5K mutations cause muscular dystrophy by unknown mechanisms. We report that loss of INPP5K in muscle caused severe disease, autophagy inhibition, and lysosome depletion. Reduced PI(4,5)P2 turnover on autolysosomes in Inpp5k-/- muscle suppressed autophagy and lysosome repopulation via ALR inhibition. Defective ALR in Inpp5k-/- myoblasts was characterized by enlarged autolysosomes and the persistence of hyperextended reformation tubules, structures that participate in membrane recycling to form lysosomes. Reduced disengagement of the PI(4,5)P2 effector clathrin was observed on reformation tubules, which we propose interfered with ALR completion. Inhibition of PI(4,5)P2 synthesis or expression of WT INPP5K but not INPP5K disease mutants in INPP5K-depleted myoblasts restored lysosomal homeostasis. Therefore, bidirectional interconversion of PI(4)P/PI(4,5)P2 on autolysosomes was integral to lysosome replenishment and autophagy function in muscle. Activation of TFEB-dependent de novo lysosome biogenesis did not compensate for loss of ALR in Inpp5k-/- muscle, revealing a dependence on this lysosome recycling pathway. Therefore, in muscle, ALR is indispensable for lysosome homeostasis during autophagy and when defective is associated with muscular dystrophy