Heterogeneity of Salmonella enterica lipopolysaccharide counteracts macrophage and antimicrobial peptide defenses.

Salmonella enterica is comprised of over 2,500 serovars, in which non-typhoidal serovars (NTS), Enteritidis (SE), and Typhimurium (STM) are the most clinically associated with human infections. Although NTS have similar genetic elements to cause disease, phenotypic variation including differences in lipopolysaccharide (LPS) composition may control immune evasion. Here, we demonstrate that macrophage host defenses and LL-37 antimicrobial efficacy against SE and STM are substantially altered by LPS heterogeneity. We found that SE evades macrophage killing by inhibiting phagocytosis while STM survives better intracellularly post-phagocytosis. SE-infected macrophages failed to activate the inflammasomes and subsequently produced less interleukin-1ß (IL-1ß), IL-18, and interferon λ. Inactivation of LPS biosynthesis genes altered LPS composition, and the SE LPS-altered mutants could no longer inhibit phagocytosis, inflammasome activation, and type II interferon signaling. In addition, SE and STM showed differential susceptibility to the antimicrobials LL-37 and colistin, and alteration of LPS structure substantially increased susceptibility to these molecules. Collectively, our findings highlight that modification of LPS composition by Salmonella increases resistance to host defenses and antibiotics.

Human neutrophil IL1ß directs intestinal epithelial cell extrusion during Salmonella infection.

Infection of the human gut by Salmonella enterica Typhimurium (STM) results in a localized inflammatory disease that is not mimicked in murine infections. To determine mechanisms by which neutrophils, as early responders to bacterial challenge, direct inflammatory programming of human intestinal epithelium, we established a multi-component human intestinal organoid (HIO) model of STM infection. HIOs were micro-injected with STM and seeded with primary human polymorphonuclear leukocytes (PMN-HIOs). PMNs did not significantly alter luminal colonization of Salmonella, but their presence reduced intraepithelial bacterial burden. Adding PMNs to infected HIOs resulted in substantial accumulation of shed TUNEL+ epithelial cells that was driven by PMN Caspase-1 activity. Inhibition of Caspases-1, -3 or -4 abrogated epithelial cell death and extrusion in the infected PMN-HIOs but only Caspase-1 inhibition significantly increased bacterial burden in the PMN-HIO epithelium. Thus, PMNs promote cell death in human intestinal epithelial cells through multiple caspases as a protective response to infection. IL-1ß was necessary and sufficient to induce cell shedding in the infected HIOs. These data support a critical innate immune function for human neutrophils in amplifying cell death and extrusion of human epithelial cells from the Salmonella-infected intestinal monolayer.

Comparative transcriptional profiling of the early host response to infection by typhoidal and non-typhoidal Salmonella serovars in human intestinal organoids.

Salmonella enterica represents over 2500 serovars associated with a wide-ranging spectrum of disease; from self-limiting gastroenteritis to invasive infections caused by non-typhoidal serovars (NTS) and typhoidal serovars, respectively. Host factors strongly influence infection outcome as malnourished or immunocompromised individuals can develop invasive infections from NTS, however, comparative analyses of serovar-specific host responses have been constrained by reliance on limited model systems. Here we used human intestinal organoids (HIOs), a three-dimensional "gut-like" in vitro system derived from human embryonic stem cells, to elucidate similarities and differences in host responses to NTS and typhoidal serovars. HIOs discriminated between the two most prevalent NTS, Salmonella enterica serovar Typhimurium (STM) and Salmonella enterica serovar Enteritidis (SE), and typhoidal serovar Salmonella enterica serovar Typhi (ST) in epithelial cell invasion, replication and transcriptional responses. Pro-inflammatory signaling and cytokine output was reduced in ST-infected HIOs compared to NTS infections, consistent with early stages of NTS and typhoidal diseases. While we predicted that ST would induce a distinct transcriptional profile from the NTS strains, more nuanced expression profiles emerged. Notably, pathways involved in cell cycle, metabolism and mitochondrial functions were downregulated in STM-infected HIOs and upregulated in SE-infected HIOs. These results correlated with suppression of cellular proliferation and induction of host cell death in STM-infected HIOs and in contrast, elevated levels of reactive oxygen species production in SE-infected HIOs. Collectively, these results suggest that the HIO model is well suited to reveal host transcriptional programming specific to infection by individual Salmonella serovars, and that individual NTS may provoke unique host epithelial responses during intestinal stages of infection.

Toxoplasma gondii exploits the host ESCRT machinery for parasite uptake of host cytosolic proteins.

Toxoplasma gondii is a master manipulator capable of effectively siphoning the resources from the host cell for its intracellular subsistence. However, the molecular underpinnings of how the parasite gains resources from its host remain largely unknown. Residing within a non-fusogenic parasitophorous vacuole (PV), the parasite must acquire resources across the limiting membrane of its replicative niche, which is decorated with parasite proteins including those secreted from dense granules. We discovered a role for the host Endosomal Sorting Complex Required for Transport (ESCRT) machinery in host cytosolic protein uptake by T. gondii by disrupting host ESCRT function. We identified the transmembrane dense granule protein TgGRA14, which contains motifs homologous to the late domain motifs of HIV-1 Gag, as a candidate for the recruitment of the host ESCRT machinery to the PV membrane. Using an HIV-1 virus-like particle (VLP) release assay, we found that the motif-containing portion of TgGRA14 is sufficient to substitute for HIV-1 Gag late domain to mediate ESCRT-dependent VLP budding. We also show that TgGRA14 is proximal to and interacts with host ESCRT components and other dense granule proteins during infection. Furthermore, analysis of TgGRA14-deficient parasites revealed a marked reduction in ingestion of a host cytosolic protein compared to WT parasites. Thus, we propose a model in which T. gondii recruits the host ESCRT machinery to the PV where it can interact with TgGRA14 for the internalization of host cytosolic proteins across the PV membrane (PVM). These findings provide new insight into how T. gondii accesses contents of the host cytosol by exploiting a key pathway for vesicular budding and membrane scission.

Implications of Ozempic and Other Semaglutide Medications for Facial Plastic Surgeons.

Obesity is a growing global health concern, leading to various health issues, including diabetes. Semaglutide-based medications, such as Ozempic, Wegovy, and Rybelsus, have emerged as potential treatments. These medications, belonging to the glucagon-like peptide-1 (GLP-1) receptor agonist class, mimic the action of GLP-1, regulating appetite and promoting weight loss. Clinical trials have shown their effectiveness in reducing body weight and improving metabolic parameters. Ozempic, though Food and Drug Administration-approved for diabetes, is also used off-label for weight loss alone. Rapid weight and fat loss with Ozempic can lead to the characteristic "Ozempic face," where facial volume and fat are depleted, resulting in wrinkles and sagging skin. Providers prescribing Ozempic seldom counsel patients about the potential impact on the face. As a result, the plastic surgery community faces a challenge in managing facial changes associated with rapid weight loss. Dermal fillers, skin tightening techniques, and surgical interventions are useful for both restoration of facial volume and to manage excess skin. Discontinuation of Ozempic should be considered prior to general anesthesia due to gastrointestinal side effects including delayed gastric emptying. As the popularity of Ozempic grows, facial plastic surgeons must be aware of both the impact on facial appearance and perioperative considerations.

Transcutaneous Electrical Stimulation for Neurogenic Bladder Dysfunction Following Spinal Cord Injury: Meta-Analysis of Randomized Controlled Trials.

OBJECTIVES: To assess the efficacy of transcutaneous electrical nerve stimulation (TENS) for neurogenic bladder dysfunction secondary to spinal cord injury (SCI). MATERIALS AND METHODS: A systematic search of MEDLINE, EMBASE, Web of Science, Scopus, and Cochrane libraries up to February 2021 was performed using PRISMA methodology. All randomized controlled trials (RCTs) that studied TENS for neurogenic bladder in a SCI population were included. The primary outcomes of interest were maximum cystometric capacity (MCC) and maximum detrusor pressure (Pdet). Meta-analysis was conducted with RevMan v5.3. RESULTS: Six RCTs involving 353 participants were included. Meta-analysis showed that TENS significantly increased MCC (standardized mean difference 1.11, 95% confidence interval [CI] 0.08-2.14, p = 0.03, I2  = 54%) in acute SCI. No benefits were seen for maximum Pdet. TENS was associated with no major adverse events. CONCLUSIONS: TENS may be an effective, safe intervention for neurogenic bladder dysfunction following SCI. Further studies are essential to confirm these results and more work is required to determine optimal stimulation parameters and duration of the treatment.

Citizen science networks in natural history and the collective validation of biodiversity data.

Biodiversity data are in increasing demand to inform policy and management. A substantial portion of these data is generated in citizen science networks. To ensure the quality of biodiversity data, standards and criteria for validation have been put in place. We used interviews and document analysis from the United Kingdom and The Netherlands to examine how data validation serves as a point of connection between the diverse people and practices in natural history citizen science networks. We found that rather than a unidirectional imposition of standards, validation was performed collectively. Specifically, it was enacted in ongoing circulations of biodiversity records between recorders and validators as they jointly negotiated the biodiversity that was observed and the validity of the records. These collective validation practices contributed to the citizen science character or natural history networks and tied these networks together. However, when biodiversity records were included in biodiversity-information initiatives on different policy levels and scales, the circulation of records diminished. These initiatives took on a more extractive mode of data use. Validation ceased to be collective with important consequences for the natural history networks involved and citizen science more generally.

Effectiveness of community forestry in Prey Long forest, Cambodia.

Cambodia has 57% forest cover, the second highest in the Greater Mekong region, and a high deforestation rate (1.2%/year, 2005-2010). Community forestry (CF) has been proposed as a way to reduce deforestation and support livelihoods through local management of forests. CF is expanding rapidly in Cambodia. The National Forests Program aims to designate one million hectares of forest to CF by 2030. However, the effectiveness of CF in conservation is not clear due to a global lack of controlled comparisons, multiple meanings of CF, and the context-specific nature of CF implementation. We assessed the effectiveness of CF by comparing 9 CF sites with paired controls in state production forest in the area of Prey Long forest, Cambodia. We assessed forest condition in 18-20 randomly placed variable-radius plots and fixed-area regeneration plots. We surveyed 10% of households in each of the 9 CF villages to determine the proportion that used forest products, as a measure of household dependence on the forest. CF sites had fewer signs of anthropogenic damage (cut stems, stumps, and burned trees), higher aboveground biomass, more regenerating stems, and reduced canopy openness than control areas. Abundance of economically valuable species, however, was higher in control sites. We used survey results and geographic parameters to model factors affecting CF outcomes. Interaction between management type, CF or control, and forest dependence indicated that CF was more effective in cases where the community relied on forest products for subsistence use and income.

Traumatic thyrohyoid membrane rupture with hyolaryngeal separation due to strangulation injury.

Background: Cervical injuries due to hanging have a high mortality rate. Survivors may present for care with subtle symptoms that belie potentially life-threatening injuries to vital structures of the neck. Case report: We report a case of a 39-year-old male admitted to the Intensive Care Unit following attempted self-strangulation. Alert and clinically stable, his primary symptoms were pain and voice changes. His external exam was remarkable only for a cervical ligature mark and subcutaneous emphysema on palpation. CT imaging demonstrated disruption of the infrahyoid strap muscles and displacement of the hyoid and epiglottis superiorly. Subsequent flexible laryngoscopy by the Otolaryngology-Head & Neck Surgery (OTO-HNS) team revealed avulsion of the epiglottis from the thyroid cartilage and disruption of the aryepiglottic folds/false cord mucosa, resulting in an open wound into the soft tissues of the anterior neck. The airway was secured in the operating room via fiberoptic nasotracheal intubation. A tracheostomy was performed. Neck exploration revealed transection of the anterior strap muscles and thyrohyoid membrane. The wound was repaired in layers via a modified thyrohyoidopexy. At one-month follow-up, the patient was successfully decannulated and tolerating a regular diet. Conclusion: Evaluation and management of head and neck trauma requires a systematic approach and thorough evaluation, as potentially life-threatening injuries can present subtly. Swift establishment of safe airway, when needed, and prompt repair of laryngeal injuries is essential to optimal functional recovery.

Functional Oral Intake in Primary Versus Salvage Laryngectomy.

OBJECTIVE: Advanced-stage laryngeal squamous cell carcinoma is treated with primary surgery or chemoradiation. We aim to determine if there are differences in postoperative functional oral intake in primary (PL) versus salvage laryngectomees (SL). STUDY DESIGN: Retrospective cohort study. SETTING: Patients who underwent laryngectomy between 2011 and 2021. METHODS: We examined demographic, diagnostic, treatment, and swallow function data pre- and postoperatively. A follow-up survey was distributed to assess current swallow status. RESULTS: One hundred twenty-five patients were included. Preoperatively, 68.8% of patients reported dysphagia. Median functional oral intake score (FOIS) was 4.0 [interquartile range, IQR: 1.0-6.75]. The SL group had lower preop FOIS [2.0; IQR: 1.0-4.75] that did not reach significance compared to the PL group [4.5; IQR: 1.0-7.0] (P = .052). 73.4% of patients had a feeding tube. The PL group was more likely to have the tube removed [odds ratio, OR: 2.4; confidence interval, CI: 1.0-5.7]. The SL group was more likely to require feeding tube placement more than 6 months postop [OR: 6.9; CI: 1.65-32.6]. SL FOIS scores improved by 3 months postop to 5 (SL ΔFOIS = 3, P = .0150). PL scores improved to 7 [PL ΔFOIS = 2, P = .0005] at 12 to 15 months. Sixty-nine patients were contacted for a follow-up survey and 16 completed this survey. 30.4% patients reported dietary restrictions (mean 4.4 years postop). CONCLUSION: Patients undergoing SL appear to obtain similar swallow outcomes compared to PL at 3 to 6 months postlaryngectomy, but plateau. The PL group continues to improve up to 1 year postoperatively. Fifty percent of patients report on-going dysphagia after 5 years.

Thrombolysis exacerbates cerebrovascular injury after ischemic stroke via a VEGF-B dependent effect on adipose lipolysis.

Cerebrovascular injuries leading to edema and hemorrhage after ischemic stroke are common. The mechanisms underlying these events and how they are connected to known risk factors for poor outcome, like obesity and diabetes, is relatively unknown. Herein we demonstrate that increased adipose tissue lipolysis is a dominating risk factor for the development of a compromised cerebrovasculature in ischemic stroke. Reducing adipose lipolysis by VEGF-B antagonism improved vascular integrity by reducing ectopic cerebrovascular lipid deposition. Thrombolytic therapy in ischemic stroke using tissue plasminogen activator (tPA) leads to increased risk of hemorrhagic complications, substantially limiting the use of thrombolytic therapy. We provide evidence that thrombolysis with tPA promotes adipose tissue lipolysis, leading to a rise in plasma fatty acids and lipid accumulation in the ischemic cerebrovasculature after stroke. VEGF-B blockade improved the efficacy and safety of thrombolysis suggesting the potential use of anti-VEGF-B therapy to extend the therapeutic window for stroke management.

Oropharyngeal Teratoma: Five-Month-Old Presenting With Failure to Thrive and Severe Obstructive Sleep Apnea.

Oropharyngeal teratomas are an extremely rare congenital tumor. They are often diagnosed prenatally and can cause significant airway obstruction and feeding difficulties at birth. We present a five-month-old female that was diagnosed with a palatal teratoma that presented with failure to thrive, difficulty feeding, and eventually with severe obstructive sleep apnea. We present a five-month-old term, otherwise healthy female who became stridulous after an episode of the respiratory syncytial virus at one month old. At three months old, an otolaryngologist diagnosed mild laryngomalacia with no mass identified, and no surgical intervention was recommended. Due to continued poor weight gain, at four months old, a nasogastric tube was placed. She was subsequently admitted for further workup. She had severe stridor, a failure to thrive, and was in the 0.07th percentile for weight. Workup revealed severe obstructive sleep apnea and a palatal mass obstructing her left oropharynx. A biopsy and debulking of the mass was performed in the operating room. Pathology resulted as a mature teratoma with evidence of glial and intestinal tissue. There are no pathognomonic characteristics found on imaging to diagnose teratomas, and diagnosis is made with pathologic identification of two of the three germ cell layers. Although most teratomas are benign, there is potential for malignant transformation involving any of the represented germ cell layers. Many teratomas are diagnosed prenatally and can be quite large, often requiring Ex Utero Intrapartum Treatment (EXIT) procedure at birth to establish a safe airway. Overall, this case highlights the importance of a thorough head and neck exam, including a bilateral flexible laryngoscopy, when evaluating an infant with airway obstruction. Providers evaluating these patients should consider oropharyngeal masses, such as teratoma, as part of the differential to ensure accurate and timely diagnosis.

Cardiolipin coordinates inflammatory metabolic reprogramming through regulation of Complex II disassembly and degradation.

Macrophage metabolic plasticity enables repurposing of electron transport from energy generation to inflammation and host defense. Altered respiratory complex II function has been implicated in cancer, diabetes, and inflammation, but regulatory mechanisms are incompletely understood. Here, we show that macrophage inflammatory activation triggers Complex II disassembly and succinate dehydrogenase subunit B loss through sequestration and selective mitophagy. Mitochondrial fission supported lipopolysaccharide-stimulated succinate dehydrogenase subunit B degradation but not sequestration. We hypothesized that this Complex II regulatory mechanism might be coordinated by the mitochondrial phospholipid cardiolipin. Cardiolipin synthase knockdown prevented lipopolysaccharide-induced metabolic remodeling and Complex II disassembly, sequestration, and degradation. Cardiolipin-depleted macrophages were defective in lipopolysaccharide-induced pro-inflammatory cytokine production, a phenotype partially rescued by Complex II inhibition. Thus, cardiolipin acts as a critical organizer of inflammatory metabolic remodeling.

Improving continence management for people with dementia in the community in Aotearoa, New Zealand: Protocol for a mixed methods study.

BACKGROUND: The number of people living with dementia (PLWD) in Aotearoa New Zealand (NZ) was estimated at 96,713 in 2020 and it is anticipated that this number will increase to 167,483 by 2050, including an estimated 12,039 Maori (indigenous people of NZ) with dementia. Experiencing urinary incontinence (UI) or faecal incontinence (FI) is common for PLWD, particularly at the later stages of the disease. However, there is no robust estimate for either prevalence or incidence of UI or FI for PLWD in NZ. Although caregivers rate independent toilet use as the most important activity of daily living to be preserved, continence care for PLWD in the community is currently not systematised and there is no structured care pathway. The evidence to guide continence practice is limited, and more needs to be known about caregiving and promoting continence and managing incontinence for PLWD in the community. This project will seek to understand the extent of the challenge and current practices of health professionals, PLWD, caregivers and family; identify promising strategies; co-develop culturally appropriate guidelines and support materials to improve outcomes; and identify appropriate quality indicators so that good continence care can be measured in future interventions. METHODS AND ANALYSIS: A four-phase mixed methods study will be delivered over three years: three phases will run concurrently, followed by a fourth transformative sequential phase. Phase 1 will identify the prevalence and incidence of incontinence for PLWD in the community using a cohort study from standardised home care interRAI assessments. Phase 2 will explore continence management for PLWD in the community through a review of clinical policies and guidance from publicly funded continence services, and qualitative focus group interviews with health professionals. Phase 3 will explore experiences, strategies, impact and consequences of promoting continence and managing incontinence for PLWD in the community through secondary data analysis of an existing carers' study, and collecting new cross-sectional and longitudinal qualitative data from Maori and non-Maori PLWD and their caregivers. In Phase 4, two adapted 3-stage Delphi processes will be used to co-produce clinical guidelines and a core outcome set, while a series of workshops will be used to co-produce caregiver resources.

Improving Control of Gene Therapy-Based Neurotrophin Delivery for Inner Ear Applications.

Background: Survival and integrity of the spiral ganglion is vital for hearing in background noise and for optimal functioning of cochlear implants. Numerous studies have demonstrated that supplementation of supraphysiologic levels of the neurotrophins BDNF and NT-3 by pumps or gene therapy strategies supports spiral ganglion survival. The endogenous physiological levels of growth factors within the inner ear, although difficult to determine, are likely extremely low within the normal inner ear. Thus, novel approaches for the long-term low-level delivery of neurotrophins may be advantageous. Objectives: This study aimed to evaluate the long-term effects of gene therapy-based low-level neurotrophin supplementation on spiral ganglion survival. Using an adenovirus serotype 28-derived adenovector delivery system, the herpes latency promoter, a weak, long expressing promoter system, has been used to deliver the BDNF or NTF3 genes to the inner ear after neomycin-induced ototoxic injury in mice. Results: Treatment of the adult mouse inner ear with neomycin resulted in acute and chronic changes in endogenous neurotrophic factor gene expression and led to a degeneration of spiral ganglion cells. Increased survival of spiral ganglion cells after adenoviral delivery of BDNF or NTF3 to the inner ear was observed. Expression of BDNF and NT-3 could be demonstrated in the damaged organ of Corti after gene delivery. Hearing loss due to overexpression of neurotrophins in the normal hearing ear was avoided when using this novel vector-promoter combination. Conclusion: Combining supporting cell-specific gene delivery via the adenovirus serotype 28 vector with a low-strength long expressing promoter potentially can provide long-term neurotrophin delivery to the damaged inner ear.

Forests in common: Learning from diversity of community forest arrangements in Europe.

Europe has a wealth of community forest arrangements. This paper aims to transcend the diversity of locally specific terms and forms, to highlight the value of considering them inclusively. Building on methods to make sense of diversity, we use reflexive grounded inquiry in fifteen cases in Italy, Scotland, Slovenia and Sweden. Within four dimensions (forest, community, relationships between them, and relationships with wider society), we identify 43 subdimensions to describe them collectively. Our approach shows how European arrangements contribute to wider discourses of collective natural resource management. Both tradition and innovation in Europe inform options for environmental governance. Arrangements challenge the distinction between 'communities of place' and 'communities of interest', with implications for social and environmental justice. They exemplify multilevel environmental governance through both vertical and horizontal connections. Emerging from long histories of political and environmental pressures, they have a role in enhancing society's connection with nature and adaptive capacity.

Salmonella enterica Serovar Typhimurium SPI-1 and SPI-2 Shape the Global Transcriptional Landscape in a Human Intestinal Organoid Model System.

The intestinal epithelium is a primary interface for engagement of the host response by foodborne pathogens, like Salmonella enterica Typhimurium. While the interaction of S Typhimurium with the mammalian host has been well studied in transformed epithelial cell lines or in the complex intestinal environment in vivo, few tractable models recapitulate key features of the intestine. Human intestinal organoids (HIOs) contain a polarized epithelium with functionally differentiated cell subtypes, including enterocytes and goblet cells and a supporting mesenchymal cell layer. HIOs contain luminal space that supports bacterial replication, are more amenable to experimental manipulation than animals and are more reflective of physiological host responses. Here, we use the HIO model to define host transcriptional responses to S Typhimurium infection, also determining host pathways dependent on Salmonella pathogenicity island-1 (SPI-1)- and -2 (SPI-2)-encoded type 3 secretion systems (T3SS). Consistent with prior findings, we find that S Typhimurium strongly stimulates proinflammatory gene expression. Infection-induced cytokine gene expression was rapid, transient, and largely independent of SPI-1 T3SS-mediated invasion, likely due to continued luminal stimulation. Notably, S Typhimurium infection led to significant downregulation of host genes associated with cell cycle and DNA repair, leading to a reduction in cellular proliferation, dependent on SPI-1 and SPI-2 T3SS. The transcriptional profile of cell cycle-associated target genes implicates multiple miRNAs as mediators of S Typhimurium-dependent cell cycle suppression. These findings from Salmonella-infected HIOs delineate common and distinct contributions of SPI-1 and SPI-2 T3SSs in inducing early host responses during enteric infection and reinforce host cell proliferation as a process targeted by SalmonellaIMPORTANCESalmonella enterica serovar Typhimurium (S Typhimurium) causes a significant health burden worldwide, yet host responses to initial stages of intestinal infection remain poorly understood. Due to differences in infection outcome between mice and humans, physiological human host responses driven by major virulence determinants of Salmonella have been more challenging to evaluate. Here, we use the three-dimensional human intestinal organoid model to define early responses to infection with wild-type S Typhimurium and mutants defective in the SPI-1 or SPI-2 type-3 secretion systems. While both secretion system mutants show defects in mouse models of oral Salmonella infection, the specific contributions of each secretion system are less well understood. We show that S Typhimurium upregulates proinflammatory pathways independently of either secretion system, while the downregulation of the host cell cycle pathways relies on both SPI-1 and SPI-2. These findings lay the groundwork for future studies investigating how SPI-1- and SPI-2-driven host responses affect infection outcome and show the potential of this model to study host-pathogen interactions with other serovars to understand how initial interactions with the intestinal epithelium may affect pathogenesis.

Mice Lacking Platelet-Derived Growth Factor D Display a Mild Vascular Phenotype.

Platelet-derived growth factor D (PDGF-D) is the most recently discovered member of the PDGF family. PDGF-D signals through PDGF receptor ß, but its biological role remains largely unknown. In contrast to other members of the PDGF family of growth factors, which have been extensively investigated using different knockout approaches in mice, PDGF-D has until now not been characterized by gene inactivation in mice. Here, we present the phenotype of a constitutive Pdgfd knockout mouse model (Pdgfd-/-), carrying a LacZ reporter used to visualize Pdgfd promoter activity. Inactivation of the Pdgfd gene resulted in a mild phenotype in C57BL/6 mice, and the offspring was viable, fertile and generally in good health. We show that Pdgfd reporter gene activity was consistently localized to vascular structures in both postnatal and adult tissues. The expression was predominantly arterial, often localizing to vascular bifurcations. Endothelial cells appeared to be the dominating source for Pdgfd, but reporter gene activity was occasionally also found in subpopulations of mural cells. Tissue-specific analyses of vascular structures revealed that NG2-expressing pericytes of the cardiac vasculature were disorganized in Pdgfd-/- mice. Furthermore, Pdgfd-/- mice also had a slightly elevated blood pressure. In summary, the vascular expression pattern together with morphological changes in NG2-expressing cells, and the increase in blood pressure, support a function for PDGF-D in regulating systemic arterial blood pressure, and suggests a role in maintaining vascular homeostasis.