Paternal microbiome perturbations impact offspring fitness

The gut microbiota operates at the interface of host-environment interactions to influence human homoeostasis and metabolic networks1-4. Environmental factors that unbalance gut microbial ecosystems can therefore shape physiological and disease-associated responses across somatic tissues5-9. However, the systemic impact of the gut microbiome on the germline-and consequently on the F1 offspring it gives rise to-is unexplored10. Here we show that the gut microbiota act as a key interface between paternal preconception environment and intergenerational health in mice. Perturbations to the gut microbiota of prospective fathers increase the probability of their offspring presenting with low birth weight, severe growth restriction and premature mortality. Transmission of disease risk occurs via the germline and is provoked by pervasive gut microbiome perturbations, including non-absorbable antibiotics or osmotic laxatives, but is rescued by restoring the paternal microbiota before conception. This effect is linked with a dynamic response to induced dysbiosis in the male reproductive system, including impaired leptin signalling, altered testicular metabolite profiles and remapped small RNA payloads in sperm. As a result, dysbiotic fathers trigger an elevated risk of in utero placental insufficiency, revealing a placental origin of mammalian intergenerational effects. Our study defines a regulatory 'gut-germline axis' in males, which is sensitive to environmental exposures and programmes offspring fitness through impacting placenta function.

Independent endothelial functions of PIEZO1 and TRPV4 in hepatic portal vein and predominance of PIEZO1 in mechanical and osmotic stress

BACKGROUND & AIMS

PIEZO1 and TRPV4 are mechanically and osmotically regulated calcium-permeable channels. The aim of this study was to determine the relevance and relationship of these channels in the contractile tone of the hepatic portal vein, which experiences mechanical and osmotic variations as it delivers blood to the liver from the intestines, gallbladder, pancreas and spleen.

METHODS

Wall tension was measured in freshly dissected portal veins from adult male mice, which were genetically unmodified or modified for either a non-disruptive tag in native PIEZO1 or endothelial-specific PIEZO1 deletion. Pharmacological agents were used to activate or inhibit PIEZO1, TRPV4 and associated pathways, including Yoda1 and Yoda2 for PIEZO1 and GSK1016790A for TRPV4 agonism, respectively.

RESULTS

PIEZO1 activation leads to nitric oxide synthase- and endothelium-dependent relaxation of the portal vein. TRPV4 activation causes contraction, which is also endothelium-dependent but independent of nitric oxide synthase. The TRPV4-mediated contraction is suppressed by inhibitors of phospholipase A2 and cyclooxygenases and mimicked by prostaglandin E2 , suggesting mediation by arachidonic acid metabolism. TRPV4 antagonism inhibits the effect of agonising TRPV4 but not PIEZO1. Increased wall stretch and hypo-osmolality inhibit TRPV4 responses while lacking effects on or amplifying PIEZO1 responses.

CONCLUSIONS

The portal vein contains independently functioning PIEZO1 channels and TRPV4 channels in the endothelium, the pharmacological activation of which leads to opposing effects of vessel relaxation (PIEZO1) and contraction (TRPV4). In mechanical and osmotic strain, the PIEZO1 mechanism dominates. Modulators of these channels could present important new opportunities for manipulating liver perfusion and regeneration in disease and surgical procedures.

PIEZO1 and PECAM1 interact at cell-cell junctions and partner in endothelial force sensing

Two prominent concepts for the sensing of shear stress by endothelium are the PIEZO1 channel as a mediator of mechanically activated calcium ion entry and the PECAM1 cell adhesion molecule as the apex of a triad with CDH5 and VGFR2. Here, we investigated if there is a relationship. By inserting a non-disruptive tag in native PIEZO1 of mice, we reveal in situ overlap of PIEZO1 with PECAM1. Through reconstitution and high resolution microscopy studies we show that PECAM1 interacts with PIEZO1 and directs it to cell-cell junctions. PECAM1 extracellular N-terminus is critical in this, but a C-terminal intracellular domain linked to shear stress also contributes. CDH5 similarly drives PIEZO1 to junctions but unlike PECAM1 its interaction with PIEZO1 is dynamic, increasing with shear stress. PIEZO1 does not interact with VGFR2. PIEZO1 is required in Ca2+-dependent formation of adherens junctions and associated cytoskeleton, consistent with it conferring force-dependent Ca2+ entry for junctional remodelling. The data suggest a pool of PIEZO1 at cell junctions, the coming together of PIEZO1 and PECAM1 mechanisms and intimate cooperation of PIEZO1 and adhesion molecules in tailoring junctional structure to mechanical requirement.

A rare human variant that disrupts GPR10 signalling causes weight gain in mice

Disruption of brain-expressed G protein-coupled receptor-10 (GPR10) causes obesity in animals. Here, we identify multiple rare variants in GPR10 in people with severe obesity and in normal weight controls. These variants impair ligand binding and G protein-dependent signalling in cells. Transgenic mice harbouring a loss of function GPR10 variant found in an individual with obesity, gain excessive weight due to decreased energy expenditure rather than increased food intake. This evidence supports a role for GPR10 in human energy homeostasis. Therapeutic targeting of GPR10 may represent an effective weight-loss strategy.

Quantitative live imaging of Venus::BMAL1 in a mouse model reveals complex dynamics of the master circadian clock regulator

Evolutionarily conserved circadian clocks generate 24-hour rhythms in physiology and behaviour that adapt organisms to their daily and seasonal environments. In mammals, the suprachiasmatic nucleus (SCN) of the hypothalamus is the principal co-ordinator of the cell-autonomous clocks distributed across all major tissues. The importance of robust daily rhythms is highlighted by experimental and epidemiological associations between circadian disruption and human diseases. BMAL1 (a bHLH-PAS domain-containing transcription factor) is the master positive regulator within the transcriptional-translational feedback loops (TTFLs) that cell-autonomously define circadian time. It drives transcription of the negative regulators Period and Cryptochrome alongside numerous clock output genes, and thereby powers circadian time-keeping. Because deletion of Bmal1 alone is sufficient to eliminate circadian rhythms in cells and the whole animal it has been widely used as a model for molecular disruption of circadian rhythms, revealing essential, tissue-specific roles of BMAL1 in, for example, the brain, liver and the musculoskeletal system. Moreover, BMAL1 has clock-independent functions that influence ageing and protein translation. Despite the essential role of BMAL1 in circadian time-keeping, direct measures of its intra-cellular behaviour are still lacking. To fill this knowledge-gap, we used CRISPR Cas9 to generate a mouse expressing a knock-in fluorescent fusion of endogenous BMAL1 protein (Venus::BMAL1) for quantitative live imaging in physiological settings. The Bmal1Venus mouse model enabled us to visualise and quantify the daily behaviour of this core clock factor in central (SCN) and peripheral clocks, with single-cell resolution that revealed its circadian expression, anti-phasic to negative regulators, nuclear-cytoplasmic mobility and molecular abundance.

Pak2 as a Novel Therapeutic Target for Cardioprotective Endoplasmic Reticulum Stress Response

Supplemental Digital Content is available in the text.

Rationale:

Secreted and membrane-bound proteins, which account for 1/3 of all proteins, play critical roles in heart health and disease. The endoplasmic reticulum (ER) is the site for synthesis, folding, and quality control of these proteins. Loss of ER homeostasis and function underlies the pathogenesis of many forms of heart disease.

Objective:

To investigate mechanisms responsible for regulating cardiac ER function, and to explore therapeutic potentials of strengthening ER function to treat heart disease.

Methods and Results:

Screening a range of signaling molecules led to the discovery that Pak (p21-activated kinase)2 is a stress-responsive kinase localized in close proximity to the ER membrane in cardiomyocytes. We found that Pak2 cardiac deleted mice (Pak2-CKO) under tunicamycin stress or pressure overload manifested a defective ER response, cardiac dysfunction, and profound cell death. Small chemical chaperone tauroursodeoxycholic acid treatment of Pak2-CKO mice substantiated that Pak2 loss-induced cardiac damage is an ER-dependent pathology. Gene array analysis prompted a detailed mechanistic study, which revealed that Pak2 regulation of protective ER function was via the IRE (inositol-requiring enzyme)-1/XBP (X-box–binding protein)-1–dependent pathway. We further discovered that this regulation was conferred by Pak2 inhibition of PP2A (protein phosphatase 2A) activity. Moreover, IRE-1 activator, Quercetin, and adeno-associated virus serotype-9–delivered XBP-1s were able to relieve ER dysfunction in Pak2-CKO hearts. This provides functional evidence, which supports the mechanism underlying Pak2 regulation of IRE-1/XBP-1s signaling. Therapeutically, inducing Pak2 activation by genetic overexpression or adeno-associated virus serotype-9–based gene delivery was capable of strengthening ER function, improving cardiac performance, and diminishing apoptosis, thus protecting the heart from failure.

Conclusions:

Our findings uncover a new cardioprotective mechanism, which promotes a protective ER stress response via the modulation of Pak2. This novel therapeutic strategy may present as a promising option for treating cardiac disease and heart failure.

Reproducibility of CRISPR-Cas9 methods for generation of conditional mouse alleles: a multi-center evaluation

BACKGROUND

CRISPR-Cas9 gene-editing technology has facilitated the generation of knockout mice, providing an alternative to cumbersome and time-consuming traditional embryonic stem cell-based methods. An earlier study reported up to 16% efficiency in generating conditional knockout (cKO or floxed) alleles by microinjection of 2 single guide RNAs (sgRNA) and 2 single-stranded oligonucleotides as donors (referred herein as "two-donor floxing" method).

RESULTS

We re-evaluate the two-donor method from a consortium of 20 laboratories across the world. The dataset constitutes 56 genetic loci, 17,887 zygotes, and 1718 live-born mice, of which only 15 (0.87%) mice contain cKO alleles. We subject the dataset to statistical analyses and a machine learning algorithm, which reveals that none of the factors analyzed was predictive for the success of this method. We test some of the newer methods that use one-donor DNA on 18 loci for which the two-donor approach failed to produce cKO alleles. We find that the one-donor methods are 10- to 20-fold more efficient than the two-donor approach.

CONCLUSION

We propose that the two-donor method lacks efficiency because it relies on two simultaneous recombination events in cis, an outcome that is dwarfed by pervasive accompanying undesired editing events. The methods that use one-donor DNA are fairly efficient as they rely on only one recombination event, and the probability of correct insertion of the donor cassette without unanticipated mutational events is much higher. Therefore, one-donor methods offer higher efficiencies for the routine generation of cKO animal models.

Metabolic Abnormalities of Chronic High-Dose Glucocorticoids Are Not Mediated by Hypothalamic AgRP in Male Mice

Glucocorticoids are potent and widely used medicines but often cause metabolic side effects. A murine model of corticosterone treatment resulted in increased hypothalamic expression of the melanocortin antagonist AgRP in parallel with obesity and hyperglycemia. We investigated how these adverse effects develop over time, with particular emphasis on hypothalamic involvement. Wild-type and Agrp-/- male mice were treated with corticosterone for 3 weeks. Phenotypic, biochemical, protein, and mRNA analyses were undertaken on central and peripheral tissues, including white and brown adipose tissue, liver, and muscle, to determine the metabolic consequences. Corticosterone treatment induced hyperphagia within 1 day in wild-type mice, which persisted for 3 weeks. Despite this early increase in food intake, the body weight only started to increase after 10 days. Hyperinsulinemia occurred at day 1. Also, although after 2 days, alterations were present in the genes often associated with insulin resistance in several peripheral tissues, hyperglycemia only developed at 3 weeks. Throughout, sustained elevation in hypothalamic Agrp expression was present. Mice with Agrp deleted [using clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9, Agrp-/-] were partially protected against corticosterone-induced hyperphagia. However, Agrp-/- mice still had corticosterone-induced increases in body weight and adiposity similar to those of the Agrp+/+ mice. Loss of Agrp did not diminish corticosterone-induced hyperinsulinemia or correct changes in hepatic gluconeogenic genes. Chronic glucocorticoid treatment in mice mimics many of the metabolic side effects seen in patients and leads to a robust increase in Agrp. However, AgRP does not appear to be responsible for most of the glucocorticoid-induced adverse metabolic effects.

Human TNF-Luc reporter mouse: A new model to quantify inflammatory responses

Tumour necrosis factor (TNF) is a key cytokine during inflammatory responses and its dysregulation is detrimental in many inflammatory diseases, such as rheumatoid arthritis and inflammatory bowel disease. Here, we used a bacterial artificial chromosome (BAC) construct that expresses luciferase under the control of the human TNF locus to generate a novel transgenic mouse, the hTNF.LucBAC strain. In vitro stimulation of hTNF.LucBAC cells of different origin revealed a cell specific response to stimuli demonstrating the integrated construct's ability as a proxy for inflammatory gene response. Lipopolysaccharide was the most potent luciferase inducer in macrophages, while TNF was a strong activator in intestinal organoids. Lipopolysaccharide-induced luciferase activity in macrophages was downregulated by inhibitors of NF-κB pathway, as well as by Interleukin-10, a known anti-inflammatory cytokine. Moreover, the transgene-dependent luciferase activity showed a positive correlation to the endogenous murine soluble TNF secreted to the culture medium. In conclusion, the hTNF.LucBAC strain is a valuable tool for studying and screening molecules that target TNF synthesis and will allow further functional studies of the regulatory elements of the TNF locus.

ADAMTS10-mediated tissue disruption in Weill-Marchesani syndrome

Fibrillin microfibrils are extracellular matrix assemblies that form the template for elastic fibres, endow blood vessels, skin and other elastic tissues with extensible properties. They also regulate the bioavailability of potent growth factors of the TGF-β superfamily. A disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS)10 is an essential factor in fibrillin microfibril function. Mutations in fibrillin-1 or ADAMTS10 cause Weill-Marchesani syndrome (WMS) characterized by short stature, eye defects, hypermuscularity and thickened skin. Despite its importance, there is poor understanding of the role of ADAMTS10 and its function in fibrillin microfibril assembly. We have generated an ADAMTS10 WMS mouse model using Clustered Regularly Spaced Interspaced Short Palindromic Repeats and CRISPR associated protein 9 (CRISPR-Cas9) to introduce a truncation mutation seen in WMS patients. Homozygous WMS mice are smaller and have shorter long bones with perturbation to the zones of the developing growth plate and changes in cell proliferation. Furthermore, there are abnormalities in the ciliary apparatus of the eye with decreased ciliary processes and abundant fibrillin-2 microfibrils suggesting perturbation of a developmental expression switch. WMS mice have increased skeletal muscle mass and more myofibres, which is likely a consequence of an altered skeletal myogenesis. These results correlated with expression data showing down regulation of Growth differentiation factor (GDF8) and Bone Morphogenetic Protein (BMP) growth factor genes. In addition, the mitochondria in skeletal muscle are larger with irregular shape coupled with increased phospho-p38 mitogen-activated protein kinase (MAPK) suggesting muscle remodelling. Our data indicate that decreased SMAD1/5/8 and increased p38/MAPK signalling are associated with ADAMTS10-induced WMS. This model will allow further studies of the disease mechanism to facilitate the development of therapeutic interventions.

Distinct Cellular Mechanisms Underlie Smooth Muscle Turnover in Vascular Development and Repair

Supplemental Digital Content is available in the text.

Rationale:

Vascular smooth muscle turnover has important implications for blood vessel repair and for the development of cardiovascular diseases, yet lack of specific transgenic animal models has prevented it’s in vivo analysis.

Objective:

The objective of this study was to characterize the dynamics and mechanisms of vascular smooth muscle turnover from the earliest stages of embryonic development to arterial repair in the adult.

Methods and Results:

We show that CD146 is transiently expressed in vascular smooth muscle development. By using CRISPR-Cas9 genome editing and in vitro smooth muscle differentiation assay, we demonstrate that CD146 regulates the balance between proliferation and differentiation. We developed a triple-transgenic mouse model to map the fate of NG2⁺CD146⁺ immature smooth muscle cells. A series of pulse-chase experiments revealed that the origin of aortic vascular smooth muscle cells can be traced back to progenitor cells that reside in the wall of the dorsal aorta of the embryo at E10.5. A distinct population of CD146⁺ smooth muscle progenitor cells emerges during embryonic development and is maintained postnatally at arterial branch sites. To characterize the contribution of different cell types to arterial repair, we used 2 injury models. In limited wire-induced injury response, existing smooth muscle cells are the primary contributors to neointima formation. In contrast, microanastomosis leads to early smooth muscle death and subsequent colonization of the vascular wall by proliferative adventitial cells that contribute to the repair.

Conclusions:

Extensive proliferation of immature smooth muscle cells in the primitive embryonic dorsal aorta establishes the long-lived lineages of smooth muscle cells that make up the wall of the adult aorta. A discrete population of smooth muscle cells forms in the embryo and is postnatally sustained at arterial branch sites. In response to arterial injuries, existing smooth muscle cells give rise to neointima, but on extensive damage, they are replaced by adventitial cells.

Aging aggravates ischemic stroke-induced brain damage in mice with chronic peripheral infection

Ischemic stroke is confounded by conditions such as atherosclerosis, diabetes, and infection, all of which alter peripheral inflammatory processes with concomitant impact on stroke outcome. The majority of the stroke patients are elderly, but the impact of interactions between aging and inflammation on stroke remains unknown. We thus investigated the influence of age on the outcome of stroke in animals predisposed to systemic chronic infection. Th1-polarized chronic systemic infection was induced in 18-22 month and 4-month-old C57BL/6j mice by administration of Trichuris muris (gut parasite). One month after infection, mice underwent permanent middle cerebral artery occlusion and infarct size, brain gliosis, and brain and plasma cytokine profiles were analyzed. Chronic infection increased the infarct size in aged but not in young mice at 24 h. Aged, ischemic mice showed altered plasma and brain cytokine responses, while the lesion size correlated with plasma prestroke levels of RANTES. Moreover, the old, infected mice exhibited significantly increased neutrophil recruitment and upregulation of both plasma interleukin-17α and tumor necrosis factor-α levels. Neither age nor infection status alone or in combination altered the ischemia-induced brain microgliosis. Our results show that chronic peripheral infection in aged animals renders the brain more vulnerable to ischemic insults, possibly by increasing the invasion of neutrophils and altering the inflammation status in the blood and brain. Understanding the interactions between age and infections is crucial for developing a better therapeutic regimen for ischemic stroke and when modeling it as a disease of the elderly.

Allergen-induced cytokine phenotypes in mice: role of CD4 and CD8 T cell populations

BACKGROUND

CD4+ T cells expressing type 2 cytokines have been implicated in the pathogenesis of asthma to high-molecular-weight allergens. Topical exposure of BALB/c strain mice to low-molecular-weight chemical contact and respiratory allergens stimulates type 1 and type 2 cytokine secretion phenotypes, respectively.

OBJECTIVE

To examine the relative frequencies of cytokine-positive CD4+ and CD8+ T cells and their contributions to these cytokine secretion profiles. Methods Draining auricular lymph nodes were isolated 13 days after initiation of topical exposure of female BALB/c strain mice to chemical allergen, or to vehicle alone. The frequency of intracellular cytokine (IL-4 and IFN-gamma)-positive CD4+ and CD8+ lymphocytes was enumerated by flow cytometry. The relative contribution of CD4+ and CD8+ cells to cytokine secretion profiles was assessed by negative selection.

RESULTS

Exposure to allergen resulted in an increased frequency of both IFN-gamma+ CD4+ and CD8+ lymphocytes, although there were no marked differences between trimellitic anhydride (TMA)- and 2,4-dinitrochlorobenzene (DNCB)-activated lymph node cells. Treatment with TMA induced approximately five times as many IL-4+ CD4+ cells as did exposure to DNCB. This pattern of cytokine staining was also observed for a further pair of contact and respiratory allergens; respectively, formalin and fluorescein isothiocyanate.

CONCLUSION

These data demonstrate that the divergent immune responses induced in mice by different classes of chemical allergen are independent of changes in the frequency of IFN-gamma+ cells, but are associated with differential frequencies of IL-4-expressing CD4+ T cells.

Exposure of mice to the nitroso metabolite of sulfamethoxazole stimulates interleukin 5 production by CD4+ T-cells

Sulfamethoxazole hypersensitivity may be caused by production of the protein-reactive metabolite nitroso sulfamethoxazole (SMX-NO) and interaction of SMX-NO with T-cells. We have characterised the nature of the immune response induced by administration of sulfamethoxazole, sulfamethoxazole metabolites and nitrosobenzene to BALB/c mice. Drugs were administered over a 13-day period to induce polarised cytokine secretion profiles. Proliferation was measured by [(3)H] thymidine incorporation. Cytokine secretion was monitored by ELISA. Results were compared with those provoked by exposure to type 1 and type 2 chemical allergens, 2,4-dinitrochlorobenzene (DNCB) and trimellitic anhydride (TMA). CD4(+) or CD8(+) T-cells were depleted ex vivo to identify the primary source of cytokines. Lymph node activation was observed following treatment with DNCB, TMA, nitrosobenzene and SMX-NO, but not with sulfamethoxazole or sulfamethoxazole hydroxylamine (SMX-NHOH). DNCB and TMA induced type 1 and type 2 cytokine profiles, respectively. SMX-NO treatment stimulated the production of high levels of IL-5, variable amounts of IFN-gamma, and relatively low levels of IL-10 and IL-4. Nitrosobenzene-activated lymph node cells secreted only low levels of IFN-gamma and IL-5. Depletion of CD4(+) or CD8(+) T-cells from SMX-NO stimulated lymph node cells revealed that CD4(+) T-cells were the major source of IL-5. In conclusion, the data presented indicates that subcutaneous administration to mice of SMX-NO, but not the parent drug, stimulated the secretion of high levels of IL-5 from activated CD4(+) T-cells, which is consistent with the clinical profile of the drug.

Chemical allergy: considerations for the practical application of cytokine profiling

Chemical respiratory allergy is an important occupational health problem, but there are currently available no validated methods for hazard identification. This is due in part to the fact that the relevant cellular and molecular mechanisms of sensitization of the respiratory tract have been unclear, with particular controversy regarding the role of IgE. There is now increasing evidence that respiratory sensitization is associated with the preferential activation of type 2 T lymphocytes and the expression of type 2 cytokines interleukin (IL)-4, IL-5, IL-10, and IL-13. Type 2 cell products favor immediate type hypersensitivity reactions, serving as growth and differentiation factors for mast cells and eosinophils, the cellular effectors of the clinical manifestations of the allergic responses, and promoting IgE antibody production. There has been considerable interest in the application of cytokine profiling for the characterization of chemical allergens, with cytokine phenotypes analyzed in freshly isolated tissue, or following culture in the presence or absence of mitogen at the level of protein secretion or mRNA expression. Experience to date suggests that the measurement of induced cytokine secretion profiles shows promise for the hazard identification and characterization of chemical respiratory allergens. The purpose of this brief review article is to consider the approaches available and to highlight key procedural issues.

Interleukin-9 is involved in host protective immunity to intestinal nematode infection

Murine studies have demonstrated that, as with other nematodes, infection with the intestinal nematode Trichinella spiralis is associated with a pronounced intestinal mastocytosis, eosinophilia and an elevation in serum levels of total IgE. Both interleukin (IL)-4 and IL-5 are clearly important in the generation of IgE responses and eosinophilia, respectively, but the control of mucosal mastocytosis in vivo is not as well defined. Mucosal mast cells appear to be particularly important with regard to T. spiralis infections as there is good evidence to suggest their involvement in expulsion of the parasite from the host. In this study we examined the effect of the overproduction of the Th2 cytokine IL-9 on infection with this nematode. We demonstrate that naive IL-9-transgenic mice have an intense intestinal mastocytosis and high serum levels of mouse mast cell protease-1. Moreover, upon infection high titers of parasite-specific IgG1 were observed with a heightened mast cell response, which was associated with the rapid expulsion of T. spiralis from the gut. Furthermore, as depression of this mast cell response, using anti-c-kit antibodies, resulted in the inability of these mice to expel the parasite, this study clearly demonstrates an activity of IL-9 on mucosal mastocytosis and the host protective immune response in vivo.

A normative model of hospital marketing decision making

A hospital marketing model is proposed for use as a framework for applying marketing strategy and concepts to hospitals. The cells of the model, primarily summarizing the many decisions of the marketing management process as can be applied to hospitals, are justified by the health care marketing literature.

Cardiac arrest from gas embolism in scuba diving

The case of a scuba diver who suffered a cardiac arrest is presented. The history of a short, lucid interval after surfacing followed by cardiac arrest, the finding of hemoptysis, and the characteristic response to recompression therapy are consistent with the diagnosis of gas embolism. The clinical presentation and pathophysiology of gas embolism are discussed, and an approach to emergency stabilization and definitive management of gas embolism is reviewed, with emphasis on cardiac arrest.