Publications by authors named "Gwendalyn J Randolph"

168 Publications

Liver injury after small bowel resection is prevented in obesity-resistant 129S1/SvImJ mice.

Am J Physiol Gastrointest Liver Physiol 2021 Mar 17. Epub 2021 Mar 17.

Pediatric Surgery, St. Louis Children's Hospital, United States.

Background Intestinal failure-associated liver disease is a major morbidity associated with short bowel syndrome. We sought to determine if the obesity-resistant mouse strain (129S1/SvImJ) conferred protection from liver injury after small bowel resection (SBR). Methods Using a parenteral nutrition-independent model of resection-associated liver injury, C57BL/6J and 129S1/SvImJ mice underwent a 50% proximal SBR or sham operation. At post-operative week 10, hepatic steatosis, fibrosis, and cholestasis were assessed. Hepatic and systemic inflammatory pathways were evaluated using oxidative markers and abundance of tissue macrophages. Potential mechanisms of endotoxin-resistance were also explored. Results Serum lipid levels were elevated in all mouse lines. Hepatic triglyceride levels were no different between mouse strains, but there was an increased accumulation of free fatty acids in the C57BL/6J mice. Histologic and serum markers of hepatic fibrosis, steatosis, and cholestasis were significantly elevated in C57BL/6J SBR mice as well as oxidative stress markers and macrophage recruitment in both the liver and visceral white fat in C57BL/6J resected mice compared to sham controls and the 129S1/SvImJ mouse line. Serum endotoxin levels were significantly elevated in C57BL/6J mice with significant elevation of hepatic TLR4 and reduction in PPARa expression levels. Conclusions Despite high levels of serum lipids, 129S1/SvImJ mice do not develop liver inflammation, fibrosis, or cholestasis after SBR, unlike C57BL/6J mice. These data suggest that the accumulation of hepatic free fatty acids as well as increased endotoxin-driven inflammatory pathways through PPARa and TLR4 contribute to the liver injury seen in C57BL/6J mice with short bowel syndrome.
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http://dx.doi.org/10.1152/ajpgi.00284.2020DOI Listing
March 2021

30 years of observations and hopes for faster progress on promoting the status of women in science.

J Exp Med 2021 Apr;218(4)

Department of Pathology and Immunology, Washington University School of Medicine, Saint Louis, MO.

Gwendalyn Randolph shares her observations and ideas for how institutions can partner with women to support their careers in STEM.
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http://dx.doi.org/10.1084/jem.20210333DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7953269PMC
April 2021

Dendritic cells: The first step.

J Exp Med 2021 Mar;218(3)

Department of Pathology & Immunology, Washington University School of Medicine, Saint Louis, MO.

Ralph M. Steinman's work on dendritic cells began in 1973 when he described and named the cells. Reminiscent of the late Justice Ginsburg's perspective that enduring change happens not suddenly but one step at a time, the paper (1973. J. Exp. Med.https://doi.org/10.1084/jem.137.5.1142) was notably the first step in many steps of important work that revealed the nature of dendritic cells.
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http://dx.doi.org/10.1084/jem.20202077DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7888350PMC
March 2021

CC Chemokine Receptor 5 Targeted Nanoparticles Imaging the Progression and Regression of Atherosclerosis Using Positron Emission Tomography/Computed Tomography.

Mol Pharm 2021 03 16;18(3):1386-1396. Epub 2021 Feb 16.

Mallinckrodt Institute of Radiology, Washington University, St. Louis, Missouri 63110, United States.

Chemokines and chemokine receptors play an important role in the initiation and progression of atherosclerosis by mediating the trafficking of inflammatory cells. Chemokine receptor 5 (CCR5) has major implications in promoting the development of plaques to advanced stage and related vulnerability. CCR5 antagonist has demonstrated the effective inhibition of atherosclerotic progression in mice, making it a potential biomarker for atherosclerosis management. To accurately determine CCR5 , we synthesized CCR5 targeted Comb nanoparticles through a modular design and construction strategy with control over the physiochemical properties and functionalization of CCR5 targeting peptide d-Ala-peptide T-amide (DAPTA-Comb). pharmacokinetic evaluation through Cu radiolabeling showed extended blood circulation of Cu-DAPTA-Combs conjugated with 10%, 25%, and 40% DAPTA. The different organ distribution profiles of the three nanoparticles demonstrated the effect of DAPTA on not only physicochemical properties but also targeting efficiency. positron emission tomography/computed tomography (PET/CT) imaging in an apolipoprotein E knockout mouse atherosclerosis model (ApoE) showed that the three Cu-DAPTA-Combs could sensitively and specifically detect CCR5 along the progression of atherosclerotic lesions. In an ApoE-encoding adenoviral vector (AAV) induced plaque regression ApoE mouse model, decreased monocyte recruitment, CD68+ macrophages, CCR5 expression, and plaque size were all associated with reduced PET signals, which not only further confirmed the targeting efficiency of Cu-DAPTA-Combs but also highlighted the potential of these targeted nanoparticles for atherosclerosis imaging. Moreover, the up-regulation of CCR5 and colocalization with CD68+ macrophages in the necrotic core of human plaque specimens warrant further investigation for atherosclerosis prognosis.
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http://dx.doi.org/10.1021/acs.molpharmaceut.0c01183DOI Listing
March 2021

Sensory Nerves Regulate Transcriptional Dynamics of Lymph Node Cells.

Trends Immunol 2021 Mar 6;42(3):180-182. Epub 2021 Feb 6.

Department of Pathology & Immunology, St. Louis, MO 63110, USA. Electronic address:

The nervous system plays important roles in homeostasis and inflammatory responses in tissues. However, the regulation of lymph nodes (LN) by nerves remains largely unknown. Huang et al. demonstrate that LNs are innervated by unique peptidergic nociceptors that signal to various endothelial, stromal, and immune cell types in LNs.
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http://dx.doi.org/10.1016/j.it.2021.01.008DOI Listing
March 2021

Reply.

Gastroenterology 2021 Jan 21. Epub 2021 Jan 21.

Department of Pathology and Immunology, Washington University School of Medicine, St Louis, Missouri; Washington University IBD-Nutrition Study TeamDepartment of Pathology and Immunology andDepartment of MedicineWashington University School of MedicineSt Louis, Missouri.

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http://dx.doi.org/10.1053/j.gastro.2021.01.202DOI Listing
January 2021

CXCR4-Binding Positron Emission Tomography Tracers Link Monocyte Recruitment and Endothelial Injury in Murine Atherosclerosis.

Arterioscler Thromb Vasc Biol 2020 Dec 17:ATVBAHA120315053. Epub 2020 Dec 17.

Department of Pathology and Immunology, Washington University School of Medicine, St. Louis. (O.B., L.-H.H., A.E., G.J.R.).

Objective: vMIP-II (viral macrophage inflammatory protein 2)/vCCL2 binds to multiple chemokine receptors, and vMIP-II-based positron emission tomography tracer (Cu-DOTA-vMIP-II: vMIP-II tracer) accumulates at atherosclerotic lesions in mice. Given that it would be expected to react with multiple chemokine receptors on monocytes and macrophages, we wondered if its accumulation in atherosclerosis lesion-bearing mice might correlate with overall macrophage burden or, alternatively, the pace of monocyte recruitment. Approach and Results: We employed a mouse model of atherosclerosis regression involving adenoassociated virus 8 vector encoding murine Apoe (AAV-mApoE) treatment of mice where the pace of monocyte recruitment slows before macrophage burden subsequently declines. Accumulation of Cu-DOTA-vMIP-II at plaque sites was strong but declined with AAV--induced decline in monocyte recruitment, before macrophage burden reduced. Monocyte depletion indicated that monocytes and macrophages themselves were not the only target of the Cu-DOTA-vMIP-II tracer. Using fluorescence-tagged vMIP-II tracer, competitive receptor blocking with CXCR4 antagonists, endothelial-specific Cre-mediated deletion of CXCR4, CXCR4-specific tracer Cu-DOTA-FC131, and CXCR4 staining during disease progression and regression, we show endothelial cell expression of CXCR4 is a key target of Cu-DOTA-vMIP-II imaging. Expression of CXCR4 was low in nonplaque areas but strongly detected on endothelium of progressing plaques, especially on proliferating endothelium, where vascular permeability was increased and monocyte recruitment was the strongest.

Conclusions: Endothelial injury status of plaques is marked by CXCR4 expression and that this injury correlates with the tendency of such plaques to recruit monocytes. Furthermore, our findings suggest positron emission tomography tracers that mark CXCR4 can be used translationally to monitor the state of plaque injury and monocyte recruitment.
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http://dx.doi.org/10.1161/ATVBAHA.120.315053DOI Listing
December 2020

Lymphatic and Blood Network Analysis During Obesity.

J Vis Exp 2020 11 19(165). Epub 2020 Nov 19.

Université Côte d'Azur; Mediterranean Center of Molecular Medicine C3M, Team 13, Institut National de la Santé et de la Recherche Médicale (Inserm) UMR1065;

Lymphatic collecting vessels and lymph nodes are inevitably embedded in adipose tissue. The physiological significance of this observation remains still not elucidated. However, obesity is characterized by impaired lymphatic function and increased vessel permeability. Inversely, lymphatic dysfunction induces obesity in mice, suggesting a significant interplay between lymphatic vessels and the adipose tissue. Therefore, understanding factors leading to lymphatic dysfunction might open new therapeutic windows to prevent obesity and associated comorbidities. The first step in this process requires a precise and detailed visualization of the lymphatic network in healthy and inflamed adipose tissue. Here, we describe a rapid, inexpensive, and efficient method that allows to label and analyze lymphatic and blood vessels. This approach takes advantage of the skin-draining brachial lymph node localization within the subcutaneous adipose tissue. The lymphatic arborization of this tissue can be revealed by injecting fluorochrome-conjugated lectins subcutaneously. Moreover, the in vivo labeling approach provides a way to evaluate lymphatic vessel density and functions. Coupled to blood vessel, adipocyte and immune cell staining, the protocol allows for high-resolution mapping of the subcutaneous adipose tissue by 3D imaging.
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http://dx.doi.org/10.3791/61814DOI Listing
November 2020

Colonic Macrophages Combat Fungal Intoxication: Metchnikoff Would Be Pleased.

Cell 2020 Oct;183(2):305-307

Department of Pathology & Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA. Electronic address:

How the colon microenvironment confronts a breach of its epithelial border remains incompletely understood. In this issue, the laboratories of Lennon-Duménil and Vignjevic reveal a novel role for macrophages in sustaining epithelial integrity in the face of fungal metabolites.
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http://dx.doi.org/10.1016/j.cell.2020.09.046DOI Listing
October 2020

YAP and TAZ maintain PROX1 expression in the developing lymphatic and lymphovenous valves in response to VEGF-C signaling.

Development 2020 12 13;147(23). Epub 2020 Dec 13.

Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA

Lymphatic vasculature is an integral part of digestive, immune and circulatory systems. The homeobox transcription factor PROX1 is necessary for the development of lymphatic vessels, lymphatic valves (LVs) and lymphovenous valves (LVVs). We and others previously reported a feedback loop between PROX1 and vascular endothelial growth factor-C (VEGF-C) signaling. PROX1 promotes the expression of the VEGF-C receptor VEGFR3 in lymphatic endothelial cells (LECs). In turn, VEGF-C signaling maintains PROX1 expression in LECs. However, the mechanisms of PROX1/VEGF-C feedback loop remain poorly understood. Whether VEGF-C signaling is necessary for LV and LVV development is also unknown. Here, we report for the first time that VEGF-C signaling is necessary for valve morphogenesis. We have also discovered that the transcriptional co-activators YAP and TAZ are required to maintain PROX1 expression in LVs and LVVs in response to VEGF-C signaling. Deletion of and in the lymphatic vasculature of mouse embryos did not affect the formation of LVs or LVVs, but resulted in the degeneration of these structures. Our results have identified VEGF-C, YAP and TAZ as a crucial molecular pathway in valve development.
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http://dx.doi.org/10.1242/dev.195453DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7758626PMC
December 2020

Limited proliferation capacity of aortic intima resident macrophages requires monocyte recruitment for atherosclerotic plaque progression.

Nat Immunol 2020 10 7;21(10):1194-1204. Epub 2020 Sep 7.

Department of Pathology and Immunology, Washington University School of Medicine, Saint Louis, MO, USA.

Early atherosclerosis depends upon responses by immune cells resident in the intimal aortic wall. Specifically, the healthy intima is thought to be populated by vascular dendritic cells (DCs) that, during hypercholesterolemia, initiate atherosclerosis by being the first to accumulate cholesterol. Whether these cells remain key players in later stages of disease is unknown. Using murine lineage-tracing models and gene expression profiling, we reveal that myeloid cells present in the intima of the aortic arch are not DCs but instead specialized aortic intima resident macrophages (Mac) that depend upon colony-stimulating factor 1 and are sustained by local proliferation. Although Mac comprise the earliest foam cells in plaques, their proliferation during plaque progression is limited. After months of hypercholesterolemia, their presence in plaques is overtaken by recruited monocytes, which induce Mac-defining genes. These data redefine the lineage of intimal phagocytes and suggest that proliferation is insufficient to sustain generations of macrophages during plaque progression.
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http://dx.doi.org/10.1038/s41590-020-0768-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7502558PMC
October 2020

Ischemia reperfusion injury provokes adverse left ventricular remodeling in dysferlin-deficient hearts through a pathway that involves TIRAP dependent signaling.

Sci Rep 2020 08 24;10(1):14129. Epub 2020 Aug 24.

Center for Cardiovascular Research, Cardiovascular Division, Division of Cardiology, Washington University School of Medicine, 660 S. Euclid Ave,, Campus Box 8086, St. Louis, MO, 63110, USA.

Cardiac myocytes have multiple cell autonomous mechanisms that facilitate stabilization and repair of damaged sarcolemmal membranes following myocardial injury. Dysferlin is a protein which facilitates membrane repair by promoting membrane resealing. Although prior studies have shown that dysferlin-deficient (Dysf) mouse hearts have an impaired recovery from acute ischemia/reperfusion (I/R) injury ex vivo, the role of dysferlin in mediating the recovery from myocardial injury in vivo is unknown. Here we show that Dysf mice develop adverse LV remodeling following I/R injury secondary to the collateral damage from sustained myocardial inflammation within the infarct zone. Backcrossing Dysf mice with mice lacking signaling through the Toll-Interleukin 1 Receptor Domain-Containing Adaptor Protein (Tirap), attenuated inflammation and abrogated adverse LV remodeling following I/R injury. Subsequent studies using Poloxamer 188 (P188), a membrane resealing reagent, demonstrated that P188 did not attenuate inflammation nor prevent adverse LV remodeling in Dysf mice following I/R injury. Viewed together these studies reveal a previously unappreciated role for the importance of membrane sealing and the resolution of inflammation following myocardial injury.
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http://dx.doi.org/10.1038/s41598-020-71079-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7445276PMC
August 2020

The Lymphatic Vasculature in the 21 Century: Novel Functional Roles in Homeostasis and Disease.

Cell 2020 07;182(2):270-296

Centre for Cancer Biology, University of South Australia and SA Pathology, Adelaide, SA, Australia.

Mammals have two specialized vascular circulatory systems: the blood vasculature and the lymphatic vasculature. The lymphatic vasculature is a unidirectional conduit that returns filtered interstitial arterial fluid and tissue metabolites to the blood circulation. It also plays major roles in immune cell trafficking and lipid absorption. As we discuss in this review, the molecular characterization of lymphatic vascular development and our understanding of this vasculature's role in pathophysiological conditions has greatly improved in recent years, changing conventional views about the roles of the lymphatic vasculature in health and disease. Morphological or functional defects in the lymphatic vasculature have now been uncovered in several pathological conditions. We propose that subtle asymptomatic alterations in lymphatic vascular function could underlie the variability seen in the body's response to a wide range of human diseases.
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http://dx.doi.org/10.1016/j.cell.2020.06.039DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7392116PMC
July 2020

Postprandial Chylomicron Output and Transport Through Intestinal Lymphatics Are Not Impaired in Active Crohn's Disease.

Gastroenterology 2020 11 15;159(5):1955-1957.e2. Epub 2020 Jul 15.

Department of Pathology and Immunology, Washington University School of Medicine, Saint Louis, Missouri. Electronic address:

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http://dx.doi.org/10.1053/j.gastro.2020.07.012DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7680355PMC
November 2020

Peripheral nerve resident macrophages share tissue-specific programming and features of activated microglia.

Nat Commun 2020 05 21;11(1):2552. Epub 2020 May 21.

Division of Immunobiology, Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO, 63110, USA.

Whereas microglia are recognized as fundamental players in central nervous system (CNS) development and function, much less is known about macrophages of the peripheral nervous system (PNS). Here, by comparing gene expression across neural and conventional tissue-resident macrophages, we identified transcripts that were shared among neural resident macrophages as well as selectively enriched in PNS macrophages. Remarkably, PNS macrophages constitutively expressed genes previously identified to be upregulated by activated microglia during aging, neurodegeneration, or loss of Sall1. Several microglial activation-associated and PNS macrophage-enriched genes were also expressed in spinal cord microglia at steady state. We further show that PNS macrophages rely on IL-34 for maintenance and arise from both embryonic and hematopoietic precursors, while their expression of activation-associated genes did not differ by ontogeny. Collectively, these data uncover shared and unique features between neural resident macrophages and emphasize the role of nerve environment for shaping PNS macrophage identity.
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http://dx.doi.org/10.1038/s41467-020-16355-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7242366PMC
May 2020

Kir6.1-dependent K channels in lymphatic smooth muscle and vessel dysfunction in mice with Kir6.1 gain-of-function.

J Physiol 2020 08 30;598(15):3107-3127. Epub 2020 May 30.

Department of Cell Biology and Physiology, Washington University School of Medicine, St Louis, MO, 63110, USA.

Key Points: Spontaneous contractions are essential for normal lymph transport and these contractions are exquisitely sensitive to the K channel activator pinacidil. K channel Kir6.1 and SUR2B subunits are expressed in mouse lymphatic smooth muscle (LSM) and form functional K channels as verified by electrophysiological techniques. Global deletion of Kir6.1 or SUR2 subunits results in severely impaired lymphatic contractile responses to pinacidil. Smooth muscle-specific expression of Kir6.1 gain-of-function mutant (GoF) subunits results in profound lymphatic contractile dysfunction and LSM hyperpolarization that is partially rescued by the K inhibitor glibenclamide. In contrast, lymphatic endothelial-specific expression of Kir6.1 GoF has essentially no effect on lymphatic contractile function. The high sensitivity of LSM to K channel GoF offers an explanation for the lymphoedema observed in patients with Cantú syndrome, a disorder caused by gain-of-function mutations in genes encoding Kir6.1 or SUR2, and suggests that glibenclamide may be an appropriate therapeutic agent.

Abstract: This study aimed to understand the functional expression of K channel subunits in distinct lymphatic cell types, and assess the consequences of altered K channel activity on lymphatic pump function. K channel subunits Kir6.1 and SUR2B were expressed in mouse lymphatic muscle by PCR, but only Kir6.1 was expressed in lymphatic endothelium. Spontaneous contractions of popliteal lymphatics from wild-type (WT) (C57BL/6J) mice, assessed by pressure myography, were very sensitive to inhibition by the SUR2-specific K channel activator pinacidil, which hyperpolarized both mouse and human lymphatic smooth muscle (LSM). In vessels from mice with deletion of Kir6.1 (Kir6.1 ) or SUR2 (SUR2[STOP]) subunits, contractile parameters were not significantly different from those of WT vessels, suggesting that basal K channel activity in LSM is not an essential component of the lymphatic pacemaker, and does not exert a strong influence over contractile strength. However, these vessels were >100-fold less sensitive than WT vessels to pinacidil. Smooth muscle-specific expression of a Kir6.1 gain-of-function (GoF) subunit resulted in severely impaired lymphatic contractions and hyperpolarized LSM. Membrane potential and contractile activity was partially restored by the K channel inhibitor glibenclamide. In contrast, lymphatic endothelium-specific expression of Kir6.1 GoF subunits had negligible effects on lymphatic contraction frequency or amplitude. Our results demonstrate a high sensitivity of lymphatic contractility to K channel activators through activation of Kir6.1/SUR2-dependent channels in LSM. In addition, they offer an explanation for the lymphoedema observed in patients with Cantú syndrome, a disorder caused by gain-of-function mutations in genes encoding Kir6.1/SUR2.
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http://dx.doi.org/10.1113/JP279612DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7641979PMC
August 2020

Myeloid-specific Asxl2 deletion limits diet-induced obesity by regulating energy expenditure.

J Clin Invest 2020 05;130(5):2644-2656

Department of Pathology and Immunology and.

We previously established that global deletion of the enhancer of trithorax and polycomb (ETP) gene, Asxl2, prevents weight gain. Because proinflammatory macrophages recruited to adipose tissue are central to the metabolic complications of obesity, we explored the role of ASXL2 in myeloid lineage cells. Unexpectedly, mice without Asxl2 only in myeloid cells (Asxl2ΔLysM) were completely resistant to diet-induced weight gain and metabolically normal despite increased food intake, comparable activity, and equivalent fecal fat. Asxl2ΔLysM mice resisted HFD-induced adipose tissue macrophage infiltration and inflammatory cytokine gene expression. Energy expenditure and brown adipose tissue metabolism in Asxl2ΔLysM mice were protected from the suppressive effects of HFD, a phenomenon associated with relatively increased catecholamines likely due to their suppressed degradation by macrophages. White adipose tissue of HFD-fed Asxl2ΔLysM mice also exhibited none of the pathological remodeling extant in their control counterparts. Suppression of macrophage Asxl2 expression, via nanoparticle-based siRNA delivery, prevented HFD-induced obesity. Thus, ASXL2 controlled the response of macrophages to dietary factors to regulate metabolic homeostasis, suggesting modulation of the cells' inflammatory phenotype may impact obesity and its complications.
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http://dx.doi.org/10.1172/JCI128687DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7190927PMC
May 2020

Effects of high-fat diet on liver injury after small bowel resection.

J Pediatr Surg 2020 Jun 28;55(6):1099-1106. Epub 2020 Feb 28.

Division of Pediatric Surgery, Department of Surgery, St. Louis Children's Hospital, Washington University in St. Louis School of Medicine, St. Louis, MO. Electronic address:

Background: The optimal regimen for enteral nutritional support in the management of children with short bowel syndrome (SBS) is not well characterized. A high fat, enteral diet is theoretically beneficial due to increased caloric density and enhanced structural adaptation. We therefore sought to determine the long-term effects of a high fat diet (HFD) on liver injury, a common complication of SBS, compared to a standard chow (SC) diet.

Methods: Using a parenteral nutrition-independent model of resection-associated liver injury, C57BL/6 mice underwent a sham operation or a 50% or 75% proximal small bowel resection (SBR). Mice in each group were then fed either a HFD (35% kcal fat) or SC (13% kcal fat). At post-operative week 15, markers of liver injury were quantified.

Results: Liver triglyceride levels were increased from 7- to 19-fold in mice on the HFD compared to mice fed SC in the sham, 50%, and 75% resection groups. Serum ALT (2.2-fold increase in 75% resected mice compared to sham controls) and AST (2.0- and 2.7-fold increases in 50% and 75% resected mice, respectively) levels as well as fibrotic liver staining were elevated only in resected mice fed a HFD.

Conclusion: Long-term enteral feeding of HFD in our murine SBS model is associated with hepatic steatosis and liver injury. Our observation that liver steatosis and injury occur independent of parenteral nutrition suggests that enteral feeding composition and magnitude of intestinal loss may make a significant contribution to intestinal failure-associated liver disease.
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http://dx.doi.org/10.1016/j.jpedsurg.2020.02.037DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7299751PMC
June 2020

Myocardial B cells are a subset of circulating lymphocytes with delayed transit through the heart.

JCI Insight 2020 02 13;5(3). Epub 2020 Feb 13.

Cardiovascular Division, Department of Medicine, and.

Current models of B lymphocyte biology posit that B cells continuously recirculate between lymphoid organs, without accumulating in peripheral healthy tissues. Nevertheless, B lymphocytes are one of the most prevalent leukocyte populations in the naive murine heart. To investigate this apparent inconsistency in the literature, we conducted a systematic analysis of myocardial B cell ontogeny, trafficking dynamics, histology, and gene expression patterns. We found that myocardial B cells represent a subpopulation of circulating B cells that make close contact with the microvascular endothelium of the heart and arrest their transit as they pass through the heart. The vast majority (>95%) of myocardial B cells remain intravascular, whereas few (<5%) myocardial B cells cross the endothelium into myocardial tissue. Analyses of mice with B cell deficiency or depletion indicated that B cells modulate the myocardial leukocyte pool composition. Analysis of B cell-deficient animals suggested that B cells modulate myocardial growth and contractility. These results transform our current understanding of B cell recirculation in the naive state and reveal a previously unknown relationship between B cells and myocardial physiology. Further work will be needed to assess the relevance of these findings to other organs.
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http://dx.doi.org/10.1172/jci.insight.134700DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7098796PMC
February 2020

Cu-ATSM Positron Emission Tomography/Magnetic Resonance Imaging of Hypoxia in Human Atherosclerosis.

Circ Cardiovasc Imaging 2020 01 8;13(1):e009791. Epub 2020 Jan 8.

Mallinckrodt Institute of Radiology (X.N., R.L., J.Z., T.F.V., N.B., J.X., R.L., R.J.G., P.K.W), Washington University School of Medicine, St Louis, MO.

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http://dx.doi.org/10.1161/CIRCIMAGING.119.009791DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7328725PMC
January 2020

Neutrophils promote VLA-4-dependent B cell antigen presentation and accumulation within the meninges during neuroinflammation.

Proc Natl Acad Sci U S A 2019 11 7;116(48):24221-24230. Epub 2019 Nov 7.

Department of Neurology, Washington University in St. Louis, St. Louis, MO 63110;

The success of B cell depletion therapies and identification of leptomeningeal ectopic lymphoid tissue (ELT) in patients with multiple sclerosis (MS) has renewed interest in the antibody-independent pathogenic functions of B cells during neuroinflammation. The timing and location of B cell antigen presentation during MS and its animal model experimental autoimmune encephalomyelitis (EAE) remain undefined. Using a new EAE system that incorporates temporal regulation of MHCII expression by myelin-specific B cells, we observed the rapid formation of large B cell clusters in the spinal cord subarachnoid space. Neutrophils preceded the accumulation of meningeal B cell clusters, and inhibition of CXCR2-mediated granulocyte trafficking to the central nervous system reduced pathogenic B cell clusters and disease severity. Further, B cell-restricted very late antigen-4 (VLA-4) deficiency abrogated EAE dependent on B cell antigen presentation. Together, our findings demonstrate that neutrophils coordinate VLA-4-dependent B cell accumulation within the meninges during neuroinflammation, a key early step in the formation of ELT observed in MS.
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http://dx.doi.org/10.1073/pnas.1909098116DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6883802PMC
November 2019

B Cell-Mediated Antigen Presentation through MHC Class II Is Dispensable for Atherosclerosis Progression.

Immunohorizons 2019 01 21;3(1):37-44. Epub 2019 Jan 21.

Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110; and

Depletion of B cells attenuates plaque development and modulates T cell responses in mouse models of atherosclerosis, suggesting that Ag presentation by B cells may promote disease progression. Thus, we set out to determine the role of B cell-mediated MHC class II (MHC II) Ag presentation during atherosclerotic plaque development. We developed murine conditional MHC II deletion and expression systems under control of the B cell-restricted CD19 promoter in an experimental model of atherosclerosis. Mice lacking MHC II expression only on B cells exhibited systemic shifts in germinal center and marginal zone B cell populations, leading to a reduced Ab response compared with littermate control animals. However, all populations were present and normal cholesterol uptake was detected in the plasma following high-fat diet treatment. In a second model, in which conditional expression of MHC II is limited only to B cells, showed similar overall cellularity characteristics compared with mice with complete MHC II deficiency. High-fat diet feeding showed no major changes in atherosclerotic plaque size or plaque cellular content in either conditional deletion or conditional expression approaches, compared with control animals. By testing the necessity and sufficiency of MHC II on B cells in the progression of atherosclerosis, we determine that MHC II on B cells does not directly regulate lesion development in murine models.
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http://dx.doi.org/10.4049/immunohorizons.1800015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6999615PMC
January 2019

A Stromal Niche Defined by Expression of the Transcription Factor WT1 Mediates Programming and Homeostasis of Cavity-Resident Macrophages.

Immunity 2019 07 20;51(1):119-130.e5. Epub 2019 Jun 20.

Department of Cancer Immunology, Genentech, South San Francisco, CA 94080, USA. Electronic address:

Tissue-resident macrophages require specific milieus for the maintenance of defining gene-expression programs. Expression of the transcription factor GATA6 is required for the homeostasis, function and localization of peritoneal cavity-resident macrophages. Gata6 expression is maintained in a non-cell autonomous manner and is elicited by the vitamin A metabolite, retinoic acid. Here, we found that the GATA6 transcriptional program is a common feature of macrophages residing in all visceral body cavities. Retinoic acid-dependent and -independent hallmark genes of GATA6 macrophages were induced by mesothelial and fibroblastic stromal cells that express the transcription factor Wilms' Tumor 1 (WT1), which drives the expression of two rate-limiting enzymes in retinol metabolism. Depletion of Wt1 stromal cells reduced the frequency of GATA6 macrophages in the peritoneal, pleural and pericardial cavities. Thus, Wt1 mesothelial and fibroblastic stromal cells constitute essential niche components supporting the tissue-specifying transcriptional landscape and homeostasis of cavity-resident macrophages.
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http://dx.doi.org/10.1016/j.immuni.2019.05.010DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6814267PMC
July 2019

Bhlhe40 mediates tissue-specific control of macrophage proliferation in homeostasis and type 2 immunity.

Nat Immunol 2019 06 6;20(6):687-700. Epub 2019 May 6.

Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO, USA.

Most tissue-resident macrophage populations develop during embryogenesis, self-renew in the steady state and expand during type 2 immunity. Whether shared mechanisms regulate the proliferation of macrophages in homeostasis and disease is unclear. Here we found that the transcription factor Bhlhe40 was required in a cell-intrinsic manner for the self-renewal and maintenance of large peritoneal macrophages (LPMs), but not that of other tissue-resident macrophages. Bhlhe40 was necessary for the proliferation, but not the polarization, of LPMs in response to the cytokine IL-4. During infection with the helminth Heligmosomoides polygyrus bakeri, Bhlhe40 was required for cell cycling of LPMs. Bhlhe40 repressed the expression of genes encoding the transcription factors c-Maf and Mafb and directly promoted expression of transcripts encoding cell cycle-related proteins to enable the proliferation of LPMs. In LPMs, Bhlhe40 bound to genomic sites co-bound by the macrophage lineage-determining factor PU.1 and to unique sites, including Maf and loci encoding cell-cycle-related proteins. Our findings demonstrate a tissue-specific control mechanism that regulates the proliferation of resident macrophages in homeostasis and type 2 immunity.
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http://dx.doi.org/10.1038/s41590-019-0382-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6531324PMC
June 2019

Expression of factor V by resident macrophages boosts host defense in the peritoneal cavity.

J Exp Med 2019 06 2;216(6):1291-1300. Epub 2019 May 2.

Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO

Macrophages resident in different organs express distinct genes, but understanding how this diversity fits into tissue-specific features is limited. Here, we show that selective expression of coagulation factor V (FV) by resident peritoneal macrophages in mice promotes bacterial clearance in the peritoneal cavity and serves to facilitate the well-known but poorly understood "macrophage disappearance reaction." Intravital imaging revealed that resident macrophages were nonadherent in peritoneal fluid during homeostasis. Bacterial entry into the peritoneum acutely induced macrophage adherence and associated bacterial phagocytosis. However, optimal control of bacterial expansion in the peritoneum also required expression of FV by the macrophages to form local clots that effectively brought macrophages and bacteria in proximity and out of the fluid phase. Thus, acute cellular adhesion and resident macrophage-induced coagulation operate independently and cooperatively to meet the challenges of a unique, open tissue environment. These events collectively account for the macrophage disappearance reaction in the peritoneal cavity.
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http://dx.doi.org/10.1084/jem.20182024DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6547866PMC
June 2019

Cytokine Circuits in Cardiovascular Disease.

Immunity 2019 04;50(4):941-954

Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63139, USA. Electronic address:

Arterial inflammation is a hallmark of atherosclerosis, and appropriate management of this inflammation represents a major unmet therapeutic need for cardiovascular disease patients. Here, we review the diverse contributions of immune cells to atherosclerosis, the mechanisms of immune cell activation in this context, and the cytokine circuits that underlie disease progression. We discuss the recent application of these insights in the form of immunotherapy to treat cardiovascular disease and highlight how studies on the cardiovascular co-morbidity that arises in autoimmunity might reveal additional roles for cytokines in atherosclerosis. Currently, data point to interleukin-1β (IL-1β), tumor necrosis factor (TNF), and IL-17 as cytokines that, at least in some settings, are effective targets to reduce cardiovascular disease progression.
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http://dx.doi.org/10.1016/j.immuni.2019.03.007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6924925PMC
April 2019

Lymphatic network remodeling after small bowel resection.

J Pediatr Surg 2019 Jun 28;54(6):1239-1244. Epub 2019 Feb 28.

Division of Pediatric Surgery, Department of Surgery, St. Louis Children's Hospital, Washington University in St. Louis School of Medicine, St. Louis, MO. Electronic address:

Background: Short gut syndrome (SGS) following massive small bowel resection (SBR) is a major cause of pediatric mortality and morbidity secondary to nutritional deficiencies and the sequelae of chronic total parenteral nutrition use, including liver steatosis. Despite the importance of lymphatic vasculature in fat absorption, lymphatic response after SBR has not been studied. We hypothesize that lymphatic vessel integrity is compromised in SGS, potentially contributing to the development of impaired lipid transport leading to liver steatosis and metabolic disease.

Methods: Mice underwent 50% proximal SBR or sham operations. Imaging of lymphatic vasculature in the lamina propria and mesentery was compared between sham and SBR Prox1 ERCre-Rosa26TdTomato mice. mRNA expression levels of lymphangiogenic markers were performed in C57BL/6J mice.

Results: Lymphatic vasculature was significantly altered after SBR. Mesenteric lymphatic collecting vessels developed new branching structures and lacked normal valves at branch points, while total mucosal lymphatic capillary area in the distal ileum decreased compared to both sham and intraoperative controls. Intestinal Vegfr3 expression also increased significantly in resected mice.

Conclusions: Intestinal lymphatics, in both the lamina propria and mesentery, dramatically remodel following SBR. This remodeling may affect lymphatic flow and function, potentially contributing to morbidities and nutritional deficiencies associated with SGS.
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http://dx.doi.org/10.1016/j.jpedsurg.2019.02.026DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6545263PMC
June 2019

Infection-Induced Transcriptional Changes in Hepatic Macrophage Metabolism Correlate With an Athero-Protective Phenotype.

Front Immunol 2018 12;9:2580. Epub 2018 Nov 12.

Department of Comparative Pathobiology, College of Veterinary Medicine, Purdue University, West Lafayette, IN, United States.

Hepatic macrophages play an essential role in the granulomatous response to infection with the parasitic helminth , but the transcriptional changes that underlie this effect are poorly understood. To explore this, we sorted the two previously recognized hepatic macrophage populations (perivascular and Kupffer cells) from naïve and -infected male mice and performed microarray analysis as part of the Immunological Genome Project. The two hepatic macrophage populations exhibited remarkably different genomic profiles. However, this diversity was substantially reduced following infection with , and in fact, both populations demonstrated increases in transcripts of the monocyte lineage, suggesting that both populations may be replenished by monocytes following infection. Pathway analysis showed a profound alteration in global metabolic pathways, including changes to phospholipid and cholesterol metabolism, as well as amino acid biosynthesis and glucagon signaling. These changes suggest a possible mechanism for the previously reported athero-protective effects of infection. Indeed, we find that male ApoE null mice fed a high-fat diet in combination with infection have reduced plaque area and increased glucose tolerance as compared to control mice. Transcript analysis of infected and control high-fat diet fed ApoE mice confirm that , and are all altered by infection, suggesting that altered hepatic macrophage metabolism is associated with - induced protection from hyperlipidemia, atherosclerosis, and glucose intolerance. These results suggest a previously unknown and unreported role of hepatic macrophages in the modulation of whole body lipid and glucose metabolism during infection and provide a template for examining the role of immunomodulation on the long-term metabolism of the host.
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http://dx.doi.org/10.3389/fimmu.2018.02580DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6240656PMC
October 2019

Interleukin-17 Drives Interstitial Entrapment of Tissue Lipoproteins in Experimental Psoriasis.

Cell Metab 2019 02 8;29(2):475-487.e7. Epub 2018 Nov 8.

Department of Pathology & Immunology, Washington University, St Louis, MO 63110, USA. Electronic address:

Lipoproteins trapped in arteries drive atherosclerosis. Extravascular low-density lipoprotein undergoes receptor uptake, whereas high-density lipoprotein (HDL) interacts with cells to acquire cholesterol and then recirculates to plasma. We developed photoactivatable apoA-I to understand how HDL passage through tissue is regulated. We focused on skin and arteries of healthy mice versus those with psoriasis, which carries cardiovascular risk in man. Our findings suggest that psoriasis-affected skin lesions program interleukin-17-producing T cells in draining lymph nodes to home to distal skin and later to arteries. There, these cells mediate thickening of the collagenous matrix, such that larger molecules including lipoproteins become entrapped. HDL transit was rescued by depleting CD4 T cells, neutralizing interleukin-17, or inhibiting lysyl oxidase that crosslinks collagen. Experimental psoriasis also increased vascular stiffness and atherosclerosis via this common pathway. Thus, interleukin-17 can reduce lipoprotein trafficking and increase vascular stiffness by, at least in part, remodeling collagen.
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http://dx.doi.org/10.1016/j.cmet.2018.10.006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6365189PMC
February 2019

Macrophage Biology, Classification, and Phenotype in Cardiovascular Disease: JACC Macrophage in CVD Series (Part 1).

J Am Coll Cardiol 2018 10;72(18):2166-2180

The Zena and Michael A. Wiener Cardiovascular Institute, Icahn School of Medicine at Mount Sinai, New York, New York. Electronic address:

Macrophages represent one of the most numerous and diverse leukocyte types in the body. Furthermore, they are important regulators and promoters of many cardiovascular disease programs. Their functions range from sensing pathogens to digesting cell debris, modulating inflammation, and producing key cytokines and other regulatory factors throughout the body. Macrophage research has undergone a renaissance in recent years, which has propelled a newfound interest in their heterogeneity as well as a new understanding of ontological differences in their development. In addition, recent technological advances such as single-cell mass-cytometry by time-of-flight have enabled phenotype and functional analyses of individual immune myeloid cells, including macrophages, at unprecedented resolution. In this Part 1 of a 4-part review series covering the macrophage in cardiovascular disease, we focus on the basic principles of macrophage development, heterogeneity, phenotype, tissue-specific differentiation, and functionality as a basis to understand their role in cardiovascular disease.
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http://dx.doi.org/10.1016/j.jacc.2018.08.2148DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6209330PMC
October 2018