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Choi D, Park E, Choi J, Lu R, Yu JS, Kim C, Zhao L, Yu J, Nakashima B, Lee S, Singhal D, Scallan JP, Zhou B, Koh CJ, Lee E, Hong YK. Piezo1 regulates meningeal lymphatic vessel drainage and alleviates excessive CSF accumulation. Nat Neurosci 2024; 27:913-926. [PMID: 38528202 PMCID: PMC11088999 DOI: 10.1038/s41593-024-01604-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Accepted: 02/15/2024] [Indexed: 03/27/2024]
Abstract
Piezo1 regulates multiple aspects of the vascular system by converting mechanical signals generated by fluid flow into biological processes. Here, we find that Piezo1 is necessary for the proper development and function of meningeal lymphatic vessels and that activating Piezo1 through transgenic overexpression or treatment with the chemical agonist Yoda1 is sufficient to increase cerebrospinal fluid (CSF) outflow by improving lymphatic absorption and transport. The abnormal accumulation of CSF, which often leads to hydrocephalus and ventriculomegaly, currently lacks effective treatments. We discovered that meningeal lymphatics in mouse models of Down syndrome were incompletely developed and abnormally formed. Selective overexpression of Piezo1 in lymphatics or systemic administration of Yoda1 in mice with hydrocephalus or Down syndrome resulted in a notable decrease in pathological CSF accumulation, ventricular enlargement and other associated disease symptoms. Together, our study highlights the importance of Piezo1-mediated lymphatic mechanotransduction in maintaining brain fluid drainage and identifies Piezo1 as a promising therapeutic target for treating excessive CSF accumulation and ventricular enlargement.
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Affiliation(s)
- Dongwon Choi
- Department of Surgery, Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
- Department of Biochemistry and Molecular Medicine, Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Eunkyung Park
- Department of Surgery, Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
- Department of Biochemistry and Molecular Medicine, Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Joshua Choi
- Department of Surgery, Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
- Department of Biochemistry and Molecular Medicine, Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Renhao Lu
- Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY, USA
| | - Jin Suh Yu
- Department of Surgery, Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
- Department of Biochemistry and Molecular Medicine, Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Chiyoon Kim
- Department of Surgery, Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
- Department of Biochemistry and Molecular Medicine, Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Luping Zhao
- Department of Surgery, Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
- Department of Biochemistry and Molecular Medicine, Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - James Yu
- Department of Surgery, Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
- Department of Biochemistry and Molecular Medicine, Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Brandon Nakashima
- Department of Surgery, Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
- Department of Biochemistry and Molecular Medicine, Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Sunju Lee
- Department of Surgery, Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
- Department of Biochemistry and Molecular Medicine, Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Dhruv Singhal
- Division of Plastic and Reconstructive Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Joshua P Scallan
- Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, FL, USA
| | - Bin Zhou
- New Cornerstone Science Laboratory, State Key Laboratory of Cell Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, China
| | - Chester J Koh
- Division of Pediatric Urology, Texas Children's Hospital, Baylor College of Medicine, Houston, TX, USA
| | - Esak Lee
- Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY, USA
| | - Young-Kwon Hong
- Department of Surgery, Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA.
- Department of Biochemistry and Molecular Medicine, Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA.
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Sedaghati F, Dixon JB, Gleason RL. A 1D model characterizing the role of spatiotemporal contraction distributions on lymph transport. Sci Rep 2023; 13:21241. [PMID: 38040740 PMCID: PMC10692214 DOI: 10.1038/s41598-023-48131-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Accepted: 11/22/2023] [Indexed: 12/03/2023] Open
Abstract
Lymphedema is a condition in which lymph transport is compromised. The factors that govern the timing of lymphatic contractions are largely unknown; however, these factors likely play a central role in lymphatic health. Computational models have proven useful in quantifying changes in lymph transport; nevertheless, there is still much unknown regarding the regulation of contractions. The purpose of this paper is to utilize computational modeling to examine the role of pacemaking activity in lymph transport. A 1D fluid-solid modeling framework was utilized to describe the interaction between the contracting vessel and the lymph flow. The distribution of contractions along a three-lymphangion chain in time and space was determined by specifying the pacemaking sites and parameters obtained from experimentation. The model effectively replicates the contractility patterns in experiments. Quantitatively, the flow rates were measured at 5.44 and 2.29 [Formula: see text], and the EF values were 78% and less than 33% in the WT and KO models, respectively, which are consistent with the literature. Applying pacemaking parameters in this modeling framework effectively captures lymphatic contractile wave propagations and their relation to lymph transport. It can serve as a motivation for conducting novel studies to evaluate lymphatic pumping function during the development of lymphedema.
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Affiliation(s)
- Farbod Sedaghati
- The George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, USA
| | - J Brandon Dixon
- The George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, USA
- The Wallace H. Coulter Georgia Tech/Emory Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA, USA
| | - Rudolph L Gleason
- The George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, USA.
- The Wallace H. Coulter Georgia Tech/Emory Department of Biomedical Engineering, Georgia Institute of Technology, 387 Technology Circle, Room 216F, Atlanta, GA, 30313, USA.
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Alamilla-Sanchez ME, Alcala-Salgado MA, Cerezo Samperio B, Prado Lozano P, Diaz Garcia JD, Gonzalez Fuentes C, Yama Estrella MB, Morales Lopez EF. Advances in the Physiology of Transvascular Exchange and A New Look At Rational Fluid Prescription. Int J Gen Med 2023; 16:2753-2770. [PMID: 37408844 PMCID: PMC10319290 DOI: 10.2147/ijgm.s405926] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Accepted: 05/28/2023] [Indexed: 07/07/2023] Open
Abstract
The Starling principle is a model that explains the transvascular distribution of fluids essentially governed by hydrostatic and oncotic forces, which dynamically allow vascular refilling according to the characteristics of the blood vessel. However, careful analysis of fluid physiology has shown that the principle, while correct, is not complete. The revised Starling principle (Michel-Weinbaum model) provides relevant information on fluid kinetics. Special emphasis has been placed on the endothelial glycocalyx, whose subendothelial area allows a restricted oncotic pressure that limits the reabsorption of fluid from the interstitial space, so that transvascular refilling occurs mainly from the lymphatic vessels. The close correlation between pathological states of the endothelium (eg: sepsis, acute inflammation, or chronic kidney disease) and the prescription of fluids forces the physician to understand the dynamics of fluids in the organism; this will allow rational fluid prescriptions. A theory that integrates the physiology of exchange and transvascular refilling is the "microconstant model", whose variables include dynamic mechanisms that can explain edematous states, management of acute resuscitation, and type of fluids for common clinical conditions. The clinical-physiological integration of the concepts will be the hinges that allow a rational and dynamic prescription of fluids.
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Affiliation(s)
| | | | | | - Pamela Prado Lozano
- Department of Nephrology, Centro Medico Nacional “20 de Noviembre”, Mexico City, Mexico
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Singh R, Heaps CL, Muthuchamy M, Deveau MA, Stewart RH, Laine GA, Dongaonkar RM. Dichotomous effects of in vivo and in vitro ionizing radiation exposure on lymphatic function. Am J Physiol Heart Circ Physiol 2023; 324:H155-H171. [PMID: 36459446 DOI: 10.1152/ajpheart.00387.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
On the one hand, lymphatic dysfunction induces interstitial edema and inflammation. On the other hand, the formation of edema and inflammation induce lymphatic dysfunction. However, informed by the earlier reports of undetected apoptosis of irradiated lymphatic endothelial cells (LECs) in vivo, lymphatic vessels are commonly considered inconsequential to ionizing radiation (IR)-induced inflammatory injury to normal tissues. Primarily because of the lack of understanding of the acute effects of IR exposure on lymphatic function, acute edema and inflammation, common sequelae of IR exposure, have been ascribed solely to blood vessel damage. Therefore, in the present study, the lymphatic acute responses to IR exposure were quantified to evaluate the hypothesis that IR exposure impairs lymphatic pumping. Rat mesenteric lymphatic vessels were irradiated in vivo or in vitro, and changes in pumping were quantified in isolated vessels in vitro. Compared with sham-treated vessels, pumping was lowered in lymphatic vessels irradiated in vivo but increased in vessels irradiated in vitro. Furthermore, unlike in blood vessels, the acute effects of IR exposure in lymphatic vessels were not mediated by nitric oxide-dependent pathways in either in vivo or in vitro irradiated vessels. After cyclooxygenase blockade, pumping was partially restored in lymphatic vessels irradiated in vitro but not in vessels irradiated in vivo. Taken together, these findings demonstrated that lymphatic vessels are radiosensitive and LEC apoptosis alone may not account for all the effects of IR exposure on the lymphatic system.NEW & NOTEWORTHY Earlier studies leading to the common belief that lymphatic vessels are radioresistant either did not characterize lymphatic pumping, deemed necessary for the resolution of edema and inflammation, or did it in vivo. By characterizing pumping in vitro, the present study, for the first time, demonstrated that lymphatic pumping was impaired in vessels irradiated in vivo and enhanced in vessels irradiated in vitro. Furthermore, the pathways implicated in ionizing radiation-induced blood vessel damage did not mediate lymphatic responses.
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Affiliation(s)
- Reetu Singh
- Michael E. DeBakey Institute for Comparative Cardiovascular Science and Biomedical Devices, Department of Veterinary Physiology and Pharmacology, Texas A&M University, College Station, Texas
| | - Cristine L Heaps
- Michael E. DeBakey Institute for Comparative Cardiovascular Science and Biomedical Devices, Department of Veterinary Physiology and Pharmacology, Texas A&M University, College Station, Texas
| | | | - Michael A Deveau
- Department of Small Animal Clinical Sciences, Texas A&M University, College Station, Texas
| | - Randolph H Stewart
- Michael E. DeBakey Institute for Comparative Cardiovascular Science and Biomedical Devices, Department of Veterinary Physiology and Pharmacology, Texas A&M University, College Station, Texas
| | - Glen A Laine
- Michael E. DeBakey Institute for Comparative Cardiovascular Science and Biomedical Devices, Department of Veterinary Physiology and Pharmacology, Texas A&M University, College Station, Texas
| | - Ranjeet M Dongaonkar
- Michael E. DeBakey Institute for Comparative Cardiovascular Science and Biomedical Devices, Department of Veterinary Physiology and Pharmacology, Texas A&M University, College Station, Texas
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Johnstone M, Xin C, Acott T, Vranka J, Wen J, Martin E, Wang RK. Valve-Like Outflow System Behavior With Motion Slowing in Glaucoma Eyes: Findings Using a Minimally Invasive Glaucoma Surgery–MIGS-Like Platform and Optical Coherence Tomography Imaging. Front Med (Lausanne) 2022; 9:815866. [PMID: 35572956 PMCID: PMC9099151 DOI: 10.3389/fmed.2022.815866] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Accepted: 03/31/2022] [Indexed: 01/01/2023] Open
Abstract
PurposeThis study aimed to investigate anatomic relationships and biomechanics of pressure-dependent trabecular meshwork and distal valve-like structure deformation in normal and glaucoma eyes using high-resolution optical coherence tomography (HR-OCT).MethodsWe controlled Schlemm’s canal (SC) pressure during imaging with HR-OCT in segments of three normal (NL) and five glaucomatous (GL) ex vivo eyes. The dissected limbal wedges were studied from 15 locations (5 NL and 10 GL). A minimally invasive glaucoma surgery (MIGS)-like cannula was inserted into the SC lumen, whereas the other end was attached to a switch between two reservoirs, one at 0, the other at 30 mm Hg. A steady-state pressure of 30 mm Hg was maintained to dilate SC and collector channels (CC) during 3D volume imaging. The resulting 3D lumen surface relationships were correlated with internal structural features using an image mask that excluded tissues surrounding SC and CC. While imaging with HR-OCT, real-time motion responses in SC and CC areas were captured by switching pressure from 0 to 30 or 30 to 0 mm Hg. NL vs. GL motion differences were compared.ResultsLumen surface and internal relationships were successfully imaged. We identified SC inlet and outlet valve-like structures. In NL and GL, the mean SC areas measured at the steady-state of 0 and 30 mm Hg were each significantly different (p < 0.0001). Synchronous changes in SC and CC lumen areas occurred in <200 ms. Measured SC area differences at the steady-state 0 and 30 mmHg, respectively, were larger in NL than GL eyes (p < 0.0001). The SC motion curves rose significantly more slowly in GL than NL (p < 0.001). Pressure waves traveled from the cannula end along the SC lumen to CC and deep intrascleral channels.ConclusionHR-OCT provided simultaneous measurements of outflow pathway lumen surfaces, internal structures, and biomechanics of real-time pressure-dependent dimension changes. We identified SC inlet and outlet valve-like structures. GL tissues underwent less motion and responded more slowly than NL, consistent with increased tissue stiffness. A MIGS-like shunt to SC permitted pulse waves to travel distally along SC lumen and into CC.
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Affiliation(s)
- Murray Johnstone
- Department of Ophthalmology, University of Washington, Seattle, WA, United States
- *Correspondence: Murray Johnstone,
| | - Chen Xin
- Department of Ophthalmology, Tongren Hospital, Beijing, China
| | - Ted Acott
- Department of Ophthalmology, Casey Eye Institute, Portland, OR, United States
| | - Janice Vranka
- Department of Ophthalmology, Casey Eye Institute, Portland, OR, United States
| | - Joanne Wen
- Department of Ophthalmology, Duke Eye Center, Durham, NC, United States
| | - Elizabeth Martin
- Department of Ophthalmology, Indiana University, Indianapolis, IN, United States
| | - Ruikang K. Wang
- Department of Ophthalmology, University of Washington, Seattle, WA, United States
- Department of Bioengineering, University of Washington, Seattle, WA, United States
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6
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Lee Y, Zawieja SD, Muthuchamy M. Lymphatic Collecting Vessel: New Perspectives on Mechanisms of Contractile Regulation and Potential Lymphatic Contractile Pathways to Target in Obesity and Metabolic Diseases. Front Pharmacol 2022; 13:848088. [PMID: 35355722 PMCID: PMC8959455 DOI: 10.3389/fphar.2022.848088] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Accepted: 02/17/2022] [Indexed: 01/19/2023] Open
Abstract
Obesity and metabolic syndrome pose a significant risk for developing cardiovascular disease and remain a critical healthcare challenge. Given the lymphatic system's role as a nexus for lipid absorption, immune cell trafficking, interstitial fluid and macromolecule homeostasis maintenance, the impact of obesity and metabolic disease on lymphatic function is a burgeoning field in lymphatic research. Work over the past decade has progressed from the association of an obese phenotype with Prox1 haploinsufficiency and the identification of obesity as a risk factor for lymphedema to consistent findings of lymphatic collecting vessel dysfunction across multiple metabolic disease models and organisms and characterization of obesity-induced lymphedema in the morbidly obese. Critically, recent findings have suggested that restoration of lymphatic function can also ameliorate obesity and insulin resistance, positing lymphatic targeted therapies as relevant pharmacological interventions. There remain, however, significant gaps in our understanding of lymphatic collecting vessel function, particularly the mechanisms that regulate the spontaneous contractile activity required for active lymph propulsion and lymph return in humans. In this article, we will review the current findings on lymphatic architecture and collecting vessel function, including recent advances in the ionic basis of lymphatic muscle contractile activity. We will then discuss lymphatic dysfunction observed with metabolic disruption and potential pathways to target with pharmacological approaches to improve lymphatic collecting vessel function.
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Affiliation(s)
- Yang Lee
- Department of Medical Physiology, College of Medicine, Texas A&M University, Bryan, TX, United States
| | - Scott D Zawieja
- Medical Pharmacology and Physiology, School of Medicine, University of Missouri, Columbia, MO, United States
| | - Mariappan Muthuchamy
- Department of Medical Physiology, College of Medicine, Texas A&M University, Bryan, TX, United States
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7
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Russell PS, Hong J, Trevaskis NL, Windsor JA, Martin ND, Phillips ARJ. Lymphatic Contractile Function: A Comprehensive Review of Drug Effects and Potential Clinical Application. Cardiovasc Res 2021; 118:2437-2457. [PMID: 34415332 DOI: 10.1093/cvr/cvab279] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Accepted: 08/18/2021] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND The lymphatic system and the cardiovascular system work together to maintain body fluid homeostasis. Despite that, the lymphatic system has been relatively neglected as a potential drug target and a source of adverse effects from cardiovascular drugs. Like the heart, the lymphatic vessels undergo phasic contractions to promote lymph flow against a pressure gradient. Dysfunction or failure of the lymphatic pump results in fluid imbalance and tissue oedema. While this can due to drug effects, it is also a feature of breast cancer-associated lymphoedema, chronic venous insufficiency, congestive heart failure and acute systemic inflammation. There are currently no specific drug treatments for lymphatic pump dysfunction in clinical use despite the wealth of data from pre-clinical studies. AIM To identify (1) drugs with direct effects on lymphatic tonic and phasic contractions with potential for clinical application, and (2) drugs in current clinical use that have a positive or negative side effect on lymphatic function. METHODS We comprehensively reviewed all studies that tested the direct effect of a drug on the contractile function of lymphatic vessels. RESULTS Of the 208 drugs identified from 193 studies, about a quarter had only stimulatory effects on lymphatic tone, contraction frequency and/or contraction amplitude. Of FDA-approved drugs, there were 14 that increased lymphatic phasic contractile function. The most frequently used class of drug with inhibitory effects on lymphatic pump function were the calcium channels blockers. CONCLUSION This review highlights the opportunity for specific drug treatments of lymphatic dysfunction in various disease states and for avoiding adverse drug effects on lymphatic contractile function.
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Affiliation(s)
- Peter S Russell
- Applied Surgery and Metabolism Laboratory, School of Biological Sciences, University of Auckland, Auckland, New Zealand.,Surgical and Translational Research Centre, Department of Surgery, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Jiwon Hong
- Applied Surgery and Metabolism Laboratory, School of Biological Sciences, University of Auckland, Auckland, New Zealand.,Surgical and Translational Research Centre, Department of Surgery, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Natalie L Trevaskis
- Monash Institute of Pharmaceutical Sciences, Faculty of Pharmacy and Pharmaceutical Sciences, Monash University, Melbourne, Australia
| | - John A Windsor
- Surgical and Translational Research Centre, Department of Surgery, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Niels D Martin
- Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Anthony R J Phillips
- Applied Surgery and Metabolism Laboratory, School of Biological Sciences, University of Auckland, Auckland, New Zealand.,Surgical and Translational Research Centre, Department of Surgery, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
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Johnstone M, Xin C, Tan J, Martin E, Wen J, Wang RK. Aqueous outflow regulation - 21st century concepts. Prog Retin Eye Res 2021; 83:100917. [PMID: 33217556 PMCID: PMC8126645 DOI: 10.1016/j.preteyeres.2020.100917] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 10/09/2020] [Accepted: 10/12/2020] [Indexed: 12/24/2022]
Abstract
We propose an integrated model of aqueous outflow control that employs a pump-conduit system in this article. Our model exploits accepted physiologic regulatory mechanisms such as those of the arterial, venous, and lymphatic systems. Here, we also provide a framework for developing novel diagnostic and therapeutic strategies to improve glaucoma patient care. In the model, the trabecular meshwork distends and recoils in response to continuous physiologic IOP transients like the ocular pulse, blinking, and eye movement. The elasticity of the trabecular meshwork determines cyclic volume changes in Schlemm's canal (SC). Tube-like SC inlet valves provide aqueous entry into the canal, and outlet valve leaflets at collector channels control aqueous exit from SC. Connections between the pressure-sensing trabecular meshwork and the outlet valve leaflets dynamically control flow from SC. Normal function requires regulation of the trabecular meshwork properties that determine distention and recoil. The aqueous pump-conduit provides short-term pressure control by varying stroke volume in response to pressure changes. Modulating TM constituents that regulate stroke volume provides long-term control. The aqueous outflow pump fails in glaucoma due to the loss of trabecular tissue elastance, as well as alterations in ciliary body tension. These processes lead to SC wall apposition and loss of motion. Visible evidence of pump failure includes a lack of pulsatile aqueous discharge into aqueous veins and reduced ability to reflux blood into SC. These alterations in the functional properties are challenging to monitor clinically. Phase-sensitive OCT now permits noninvasive, quantitative measurement of pulse-dependent TM motion in humans. This proposed conceptual model and related techniques offer a novel framework for understanding mechanisms, improving management, and development of therapeutic options for glaucoma.
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Affiliation(s)
| | - Chen Xin
- Department of Ophthalmology, Beijing Anzhen Hospital, Capital Medical University, China.
| | - James Tan
- Doheny Eye Institute and UCLA Department of Ophthalmology, USA.
| | | | | | - Ruikang K Wang
- Department of Ophthalmology, University of Washington, USA; Department of Bioengineering, University of Washington, USA.
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Mukherjee A, Nepiyushchikh Z, Michalaki E, Dixon JB. Lymphatic injury alters the contractility and mechanosensitivity of collecting lymphatics to intermittent pneumatic compression. J Physiol 2021; 599:2699-2721. [PMID: 33644884 DOI: 10.1113/jp281206] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Accepted: 02/15/2021] [Indexed: 12/14/2022] Open
Abstract
KEY POINTS We present the first in vivo evidence that lymphatic contraction can entrain with an external oscillatory mechanical stimulus. Lymphatic injury can alter collecting lymphatic contractility, but not much is known about how its mechanosensitivity to external pressure is affected, which is crucial given the current pressure application methods for treating lymphoedema. We show that oscillatory pressure waves (OPW), akin to intermittent pneumatic compression (IPC) therapy, optimally entrain lymphatic contractility and modulate function depending on the frequency and propagation speed of the OPW. We show that the OPW-induced entrainment and contractile function in the intact collecting lymphatics are enhanced 28 days after a contralateral lymphatic ligation surgery. The results show that IPC efficacy can be improved through proper selection of OPW parameters, and that collecting lymphatics adapt their function and mechanosensitivity after a contralateral injury, switching their behaviour to a pump-like configuration that may be more suited to the altered microenvironment. ABSTRACT Intermittent pneumatic compression (IPC) is commonly used to control the swelling due to lymphoedema, possibly modulating the collecting lymphatic function. Lymphoedema causes lymphatic contractile dysfunction, but the consequent alterations in the mechanosensitivity of lymphatics to IPC is not known. In the present work, the spatiotemporally varying oscillatory pressure waves (OPW) generated during IPC were simulated to study the modulation of lymphatic function by OPW under physiological and pathological conditions. OPW with three temporal frequencies and three propagation speeds were applied to rat tail collecting lymphatics. The entrainment of the lymphatics to OPW was significantly higher at a frequency of 0.05 Hz compared with 0.1 Hz and 0.2 Hz (P = 0.0054 and P = 0.014, respectively), but did not depend on the OPW propagation speed. Lymphatic function was significantly higher at a frequency of 0.05 Hz and propagation speed of 2.55 mm/s (P = 0.015). Exogenous nitric oxide was not found to alter OPW-induced entrainment. A contralateral lymphatic ligation surgery was performed to simulate partial lymphatic injury in rat tails. The intact vessels showed a significant increase in entrainment to OPW, 28 days after ligation (compared with sham) (P = 0.016), with a similar increase in lymphatic transport function (P = 0.0029). The results suggest an enhanced mechanosensitivity of the lymphatics, along with a transition to a pump-like behaviour, in response to a lymphatic injury. These results enhance our fundamental understanding of how lymphatic mechanosensitivity assists the coordination of lymphatic contractility and how this might be leveraged in IPC therapy.
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Affiliation(s)
- Anish Mukherjee
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Zhanna Nepiyushchikh
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia, 30332, USA
| | - Eleftheria Michalaki
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia, 30332, USA
| | - J Brandon Dixon
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia, 30332, USA
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10
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Stewart RH. A Modern View of the Interstitial Space in Health and Disease. Front Vet Sci 2020; 7:609583. [PMID: 33251275 PMCID: PMC7674635 DOI: 10.3389/fvets.2020.609583] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Accepted: 10/14/2020] [Indexed: 12/15/2022] Open
Abstract
Increases in the volume of the interstitial space are readily recognized clinically as interstitial edema formation in the loose connective tissue of skin, mucosa, and lung. However, the contents and the hydrostatic pressure of this interstitial fluid can be very difficult to determine even in experimental settings. These difficulties have long obscured what we are beginning to appreciate is a dynamic milieu that is subject to both intrinsic and extrinsic regulation. This review examines current concepts regarding regulation of interstitial volume, pressure, and flow and utilizes that background to address three major topics of interest that impact IV fluid administration. The first of these started with the discovery that excess dietary salt can be stored non-osmotically in the interstitial space with minimal impact on vascular volume and pressures. This led to the hypothesis that, along with the kidney, the interstitial space plays an active role in the long-term regulation of blood pressure. Second, it now appears that hypovolemic shock leads to systemic inflammatory response syndrome principally through the entry of digestive enzymes into the intestinal interstitial space and the subsequent progression of enzymes and inflammatory agents through the mesenteric lymphatic system to the general circulation. Lastly, current evidence strongly supports the non-intuitive view that the primary factor leading to inflammatory edema formation is a decrease in interstitial hydrostatic pressure that dramatically increases microvascular filtration.
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Affiliation(s)
- Randolph H Stewart
- Department of Veterinary Physiology and Pharmacology, Michael E. DeBakey Institute, Texas A&M University, College Station, TX, United States
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11
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Mathematical Modelling of the Structure and Function of the Lymphatic System. MATHEMATICS 2020. [DOI: 10.3390/math8091467] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
This paper presents current knowledge about the structure and function of the lymphatic system. Mathematical models of lymph flow in the single lymphangion, the series of lymphangions, the lymph nodes, and the whole lymphatic system are considered. The main results and further perspectives are discussed.
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12
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Pruitt LG. Lymphatic flow modulation as adjunct therapy for septic shock. Med Hypotheses 2020; 142:109748. [PMID: 32339860 DOI: 10.1016/j.mehy.2020.109748] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Accepted: 04/19/2020] [Indexed: 11/16/2022]
Abstract
The lymphatic system is an important component of human health and is critical in maintaining microcirculatory flow and immune system homeostasis. During septic shock, increased capillary permeability results in excess filtration of intravascular fluid and solutes producing interstitial edema with subsequent hydrostatic and oncotic gradient breakdown. The accumulation of interstitial fluid results in impaired solute exchange, leukocyte signaling, and aberrancy in capillary flow. Modulation of lymphatic flow during times of interstitial volume overload such as septic shock may decrease interstitial volume resulting in improved perfusion, decreased end-organ damage, and contribute to disease resolution. Multiple studies in both humans and animals have shown nitric oxide to be a potent modulator of lymphatic function. The present study suggests a hypothetical adjunct therapy for patients with septic shock through the use of phosphodiesterase inhibitors, which may improve microcirculatory flow by decreasing interstitial fluid volume via increased lymphatic fluid drainage.
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Affiliation(s)
- Louis Gordon Pruitt
- Saint Anthony Hospital, Department of Emergency Medicine, 11567 Canterwood Boulevard Northwest, Gig Harbor, WA 98332, United States.
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Nelson TS, Nepiyushchikh Z, Hooks JST, Razavi MS, Lewis T, Clement CC, Thoresen M, Cribb MT, Ross MK, Gleason RL, Santambrogio L, Peroni JF, Dixon JB. Lymphatic remodelling in response to lymphatic injury in the hind limbs of sheep. Nat Biomed Eng 2019; 4:649-661. [PMID: 31873209 DOI: 10.1038/s41551-019-0493-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Accepted: 11/15/2019] [Indexed: 02/06/2023]
Abstract
Contractile activity in the lymphatic vasculature is essential for maintaining fluid balance within organs and tissues. However, the mechanisms by which collecting lymphatics adapt to changes in fluid load and how these adaptations influence lymphatic contractile activity are unknown. Here we report a model of lymphatic injury based on the ligation of one of two parallel lymphatic vessels in the hind limb of sheep and the evaluation of structural and functional changes in the intact, remodelling lymphatic vessel over a 42-day period. We show that the remodelled lymphatic vessel displayed increasing intrinsic contractile frequency, force generation and vessel compliance, as well as decreasing flow-mediated contractile inhibition via the enzyme endothelial nitric oxide synthase. A computational model of a chain of lymphatic contractile segments incorporating these adaptations predicted increases in the flow-generation capacity of the remodelled vessel at the expense of normal mitochondrial function and elevated oxidative stress within the lymphatic muscle. Our findings may inform interventions for mitigating lymphatic muscle fatigue in patients with dysfunctional lymphatics.
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Affiliation(s)
- Tyler S Nelson
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA, USA.,George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, USA
| | - Zhanna Nepiyushchikh
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA, USA.,George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, USA
| | - Joshua S T Hooks
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA, USA.,George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, USA
| | - Mohammad S Razavi
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA, USA.,George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, USA
| | - Tristan Lewis
- College of Veterinary Medicine, University of Georgia, Athens, GA, USA
| | - Cristina C Clement
- Department of Pathology, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Merrilee Thoresen
- College of Veterinary Medicine, University of Georgia, Athens, GA, USA
| | - Matthew T Cribb
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA, USA.,George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, USA
| | - Mindy K Ross
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA, USA
| | - Rudolph L Gleason
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA, USA.,George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, USA.,Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA, USA
| | - Laura Santambrogio
- Department of Pathology, Albert Einstein College of Medicine, Bronx, NY, USA
| | - John F Peroni
- College of Veterinary Medicine, University of Georgia, Athens, GA, USA
| | - J Brandon Dixon
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA, USA. .,George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, USA. .,Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA, USA.
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14
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How many aqueous humor outflow pathways are there? Surv Ophthalmol 2019; 65:144-170. [PMID: 31622628 DOI: 10.1016/j.survophthal.2019.10.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2019] [Revised: 09/29/2019] [Accepted: 10/04/2019] [Indexed: 12/31/2022]
Abstract
The aqueous humor (AH) outflow pathways definition is still matter of intense debate. To date, the differentiation between conventional (trabecular meshwork) and unconventional (uveoscleral) pathways is widely accepted, distinguishing the different impact of the intraocular pressure on the AH outflow rate. Although the conventional route is recognized to host the main sites for intraocular pressure regulation, the unconventional pathway, with its great potential for AH resorption, seems to act as a sort of relief valve, especially when the trabecular resistance rises. Recent evidence demonstrates the presence of lymphatic channels in the eye and proposes that they may participate in the overall AH drainage and intraocular pressure regulation, in a presumably adaptive fashion. For this reason, the uveolymphatic route is increasingly thought to play an important role in the ocular hydrodynamic system physiology. As a result of the unconventional pathway characteristics, hydrodynamic disorders do not develop until the adaptive routes cannot successfully counterbalance the increased AH outflow resistance. When their adaptive mechanisms fail, glaucoma occurs. Our review deals with the standard and newly discovered AH outflow routes, with particular attention to the importance they may have in opening new therapeutic strategies in the treatment of ocular hypertension and glaucoma.
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Nizamutdinova IT, Maejima D, Nagai T, Meininger CJ, Gashev AA. Histamine as an Endothelium-Derived Relaxing Factor in Aged Mesenteric Lymphatic Vessels. Lymphat Res Biol 2017; 15:136-145. [PMID: 28453392 PMCID: PMC5488315 DOI: 10.1089/lrb.2016.0062] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Knowledge of the mechanisms by which aging affects contracting lymphatic vessels remains incomplete; therefore, the functional role of histamine in the reaction of aged lymphatic vessels to increases in flow remains unknown. METHODS AND RESULTS We measured and analyzed parameters of lymphatic contractility in isolated and pressurized rat mesenteric lymphatic vessels (MLVs) obtained from 9- and 24-month Fischer-344 rats under control conditions and after pharmacological blockade of nitric oxide (NO) by Nω-Nitro-L-arginine methyl ester hydrochloride (L-NAME, 100 μM) or/and blockade of histamine production by α-methyl-DL-histidine dihydrochloride (α-MHD, 10 μM). We also quantitatively compared results of immunohistochemical labeling of the histamine-producing enzyme, histidine decarboxylase (HDC) in adult and aged MLVs. Our data provide the first demonstration of an increased functional role of histamine as an endothelial-derived relaxing factor in aged MLVs, which appears in parallel with the abolished role of NO in the reactions of these lymph vessels to increases in flow. In addition, we found an increased expression of HDC in endothelium of aged MLVs. CONCLUSIONS Our findings provide the basis for better understanding of the processes of aging in lymphatic vessels and for setting new important directions for investigations of the aging-associated disturbances in lymph flow and the immune response.
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Affiliation(s)
- Irina Tsoy Nizamutdinova
- Department of Medical Physiology, College of Medicine, Texas A&M University Health Science Center, Temple, Texas
| | - Daisuke Maejima
- Department of Medical Physiology, College of Medicine, Texas A&M University Health Science Center, Temple, Texas
- Department of Physiology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Takashi Nagai
- Department of Medical Physiology, College of Medicine, Texas A&M University Health Science Center, Temple, Texas
- Department of Physiology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Cynthia J. Meininger
- Department of Medical Physiology, College of Medicine, Texas A&M University Health Science Center, Temple, Texas
| | - Anatoliy A. Gashev
- Department of Medical Physiology, College of Medicine, Texas A&M University Health Science Center, Temple, Texas
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Xin C, Wang RK, Song S, Shen T, Wen J, Martin E, Jiang Y, Padilla S, Johnstone M. Aqueous outflow regulation: Optical coherence tomography implicates pressure-dependent tissue motion. Exp Eye Res 2017; 158:171-186. [PMID: 27302601 PMCID: PMC5272871 DOI: 10.1016/j.exer.2016.06.007] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2016] [Revised: 05/21/2016] [Accepted: 06/09/2016] [Indexed: 12/28/2022]
Abstract
Glaucoma is a leading cause of blindness worldwide and results from damage to the optic nerve. Currently, intraocular pressure is the only treatable risk factor. Changes in aqueous outflow regulate pressure; regulation becomes abnormal in glaucoma. From inside the eye aqueous flows out through the trabecular meshwork into a venous sinus called Schlemm's canal, next into collector channels and finally returns to the episcleral vessels of the venous system. The location of aqueous outflow regulation is unknown. Ex vivo and in vivo studies implicate both pressure-dependent trabecular tissue motion and tissues distal to Schlemm's canal in regulation of aqueous outflow. Technologies have not previously been available to study these issues. New ex vivo imaging in human eyes identifies hinged flaps or leaflets at collector channel entrances using a high-resolution spectral domain optical coherence tomography (SD-OCT) platform. The hinged flaps open and close in synchrony with pressure-dependent trabecular meshwork motion. The SD-OCT platform images from the trabecular meshwork surface while experimentally changing transtrabecular pressure gradients. New in vivo imaging in human eyes uses a motion sensitive technology, phase-sensitive OCT to quantitate real-time pulse-dependent trabecular tissue motion as well as absence of such motion when aqueous access to the outflow system is blocked. The recent studies suggest that aqueous outflow regulation results from synchronous pressure-dependent motion involving a network of interconnected tissues including those distal to Schlemm's canal. The new imaging technologies may shed light on glaucoma mechanisms and provide guidance in the management of medical, laser and surgical decisions in glaucoma.
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Affiliation(s)
- Chen Xin
- Department of Bioengineering, University of Washington, USA; Department of Ophthalmology, Beijing Anzhen Hospital, Capital Medical University, China.
| | - Ruikang K Wang
- Department of Bioengineering, University of Washington, USA; Department of Ophthalmology, University of Washington, USA.
| | - Shaozhen Song
- Department of Bioengineering, University of Washington, USA.
| | - Tueng Shen
- Department of Bioengineering, University of Washington, USA; Department of Ophthalmology, University of Washington, USA.
| | - Joanne Wen
- Department of Ophthalmology, University of Washington, USA.
| | | | - Yi Jiang
- Department of Ophthalmology, University of Washington, USA.
| | - Steven Padilla
- Department of Ophthalmology, University of Washington, USA.
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17
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Carreon T, van der Merwe E, Fellman RL, Johnstone M, Bhattacharya SK. Aqueous outflow - A continuum from trabecular meshwork to episcleral veins. Prog Retin Eye Res 2017; 57:108-133. [PMID: 28028002 PMCID: PMC5350024 DOI: 10.1016/j.preteyeres.2016.12.004] [Citation(s) in RCA: 179] [Impact Index Per Article: 25.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Revised: 11/14/2016] [Accepted: 12/22/2016] [Indexed: 12/22/2022]
Abstract
In glaucoma, lowered intraocular pressure (IOP) confers neuroprotection. Elevated IOP characterizes glaucoma and arises from impaired aqueous humor (AH) outflow. Increased resistance in the trabecular meshwork (TM), a filter-like structure essential to regulate AH outflow, may result in the impaired outflow. Flow through the 360° circumference of TM structures may be non-uniform, divided into high and low flow regions, termed as segmental. After flowing through the TM, AH enters Schlemm's canal (SC), which expresses both blood and lymphatic markers; AH then passes into collector channel entrances (CCE) along the SC external well. From the CCE, AH enters a deep scleral plexus (DSP) of vessels that typically run parallel to SC. From the DSP, intrascleral collector vessels run radially to the scleral surface to connect with AH containing vessels called aqueous veins to discharge AH to blood-containing episcleral veins. However, the molecular mechanisms that maintain homeostatic properties of endothelial cells along the pathways are not well understood. How these molecular events change during aging and in glaucoma pathology remain unresolved. In this review, we propose mechanistic possibilities to explain the continuum of AH outflow control, which originates at the TM and extends through collector channels to the episcleral veins.
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Affiliation(s)
- Teresia Carreon
- Department of Ophthalmology & Bascom Palmer Eye Institute, University of Miami, Miami, USA; Department of Biochemistry and Molecular Biology, University of Miami, Miami, USA
| | - Elizabeth van der Merwe
- Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Anzio Road, Observatory, 7925 Cape Town, South Africa
| | | | - Murray Johnstone
- Department of Ophthalmology, University of Washington, Seattle, WA, USA
| | - Sanjoy K Bhattacharya
- Department of Ophthalmology & Bascom Palmer Eye Institute, University of Miami, Miami, USA; Department of Biochemistry and Molecular Biology, University of Miami, Miami, USA.
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18
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Dongaonkar RM, Nguyen TL, Quick CM, Heaps CL, Hardy J, Laine GA, Wilson E, Stewart RH. Mesenteric lymphatic vessels adapt to mesenteric venous hypertension by becoming weaker pumps. Am J Physiol Regul Integr Comp Physiol 2014; 308:R391-9. [PMID: 25519727 DOI: 10.1152/ajpregu.00196.2014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Lymphangions, the segments of lymphatic vessels between two adjacent lymphatic valves, actively pump lymph. Acute changes in transmural pressure and lymph flow have profound effects on lymphatic pump function in vitro. Chronic changes in pressure and flow in vivo have also been reported to lead to significant changes in lymphangion function. Because changes in pressure and flow are both cause and effect of adaptive processes, characterizing adaptation requires a more fundamental analysis of lymphatic muscle properties. Therefore, the purpose of the present work was to use an intact lymphangion isovolumetric preparation to evaluate changes in mesenteric lymphatic muscle mechanical properties and the intracellular Ca(2+) in response to sustained mesenteric venous hypertension. Bovine mesenteric veins were surgically occluded to create mesenteric venous hypertension. Postnodal mesenteric lymphatic vessels from mesenteric venous hypertension (MVH; n = 6) and sham surgery (Sham; n = 6) animals were isolated and evaluated 3 days after the surgery. Spontaneously contracting MVH vessels generated end-systolic active tension and end-diastolic active tension lower than the Sham vessels. Furthermore, steady-state active tension and intracellular Ca(2+) concentration levels in response to KCl stimulation were also significantly lower in MVH vessels compared with those of the Sham vessels. There was no significant difference in passive tension in lymphatic vessels from the two groups. Taken together, these results suggest that following 3 days of mesenteric venous hypertension, postnodal mesenteric lymphatic vessels adapt to become weaker pumps with decreased cytosolic Ca(2+) concentration.
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Affiliation(s)
- R M Dongaonkar
- Michael E. DeBakey Institute, Texas A&M University, College Station, Texas
| | - T L Nguyen
- Michael E. DeBakey Institute, Texas A&M University, College Station, Texas
| | - C M Quick
- Michael E. DeBakey Institute, Texas A&M University, College Station, Texas;
| | - C L Heaps
- Michael E. DeBakey Institute, Texas A&M University, College Station, Texas
| | - J Hardy
- Large Animal Clinical Sciences, Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas; and
| | - G A Laine
- Michael E. DeBakey Institute, Texas A&M University, College Station, Texas
| | - E Wilson
- Department of Medical Physiology, Texas A&M Health Science Center, Texas A&M University, College Station, Texas
| | - R H Stewart
- Michael E. DeBakey Institute, Texas A&M University, College Station, Texas
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Quick CM, Criscione JC, Kotiya A, Dongaonkar RM, Hardy J, Wilson E, Gashev AA, Laine GA, Stewart RH. Functional adaptation of bovine mesenteric lymphatic vessels to mesenteric venous hypertension. Am J Physiol Regul Integr Comp Physiol 2014; 306:R901-7. [PMID: 24671245 DOI: 10.1152/ajpregu.00185.2013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Lymph flow is the primary mechanism for returning interstitial fluid to the blood circulation. Currently, the adaptive response of lymphatic vessels to mesenteric venous hypertension is not known. This study sought to determine the functional responses of postnodal mesenteric lymphatic vessels. We surgically occluded bovine mesenteric veins to create mesenteric venous hypertension to elevate mesenteric lymph flow. Three days after surgery, postnodal mesenteric lymphatic vessels from mesenteric venous hypertension (MVH; n = 7) and sham surgery (Sham; n = 6) group animals were evaluated and compared. Contraction frequency (MVH: 2.98 ± 0.75 min(-1); Sham: 5.42 ± 0.81 min(-1)) and fractional pump flow (MVH: 1.14 ± 0.30 min(-1); Sham: 2.39 ± 0.32 min(-1)) were significantly lower in the venous occlusion group. These results indicate that postnodal mesenteric lymphatic vessels adapt to mesenteric venous hypertension by reducing intrinsic contractile activity.
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Affiliation(s)
- Christopher M Quick
- Michael E. DeBakey Institute, Texas A&M University, College Station, Texas; Department of Biomedical Engineering, Texas A&M University, College Station, Texas;
| | - John C Criscione
- Michael E. DeBakey Institute, Texas A&M University, College Station, Texas; Department of Biomedical Engineering, Texas A&M University, College Station, Texas
| | - Akhilesh Kotiya
- Department Biomedical Engineering, Dalhousie University, Halifax, Nova Scotia, Canada
| | | | - Joanne Hardy
- Michael E. DeBakey Institute, Texas A&M University, College Station, Texas; Large Animal Clinical Sciences, Texas A&M University, College Station, Texas; and
| | - Emily Wilson
- Michael E. DeBakey Institute, Texas A&M University, College Station, Texas; Systems Biology and Translational Medicine, Texas A&M Health Science Center, Temple, Texas
| | - Anatoliy A Gashev
- Michael E. DeBakey Institute, Texas A&M University, College Station, Texas; Systems Biology and Translational Medicine, Texas A&M Health Science Center, Temple, Texas
| | - Glen A Laine
- Michael E. DeBakey Institute, Texas A&M University, College Station, Texas
| | - Randolph H Stewart
- Michael E. DeBakey Institute, Texas A&M University, College Station, Texas
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20
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Role of RhoA in Regulating the Pump Function of Isolated Lymphatics From Hemorrhagic Shock Rats. Shock 2013; 40:49-58. [DOI: 10.1097/shk.0b013e31829635cf] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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Dongaonkar RM, Nguyen TL, Quick CM, Hardy J, Laine GA, Wilson E, Stewart RH. Adaptation of mesenteric lymphatic vessels to prolonged changes in transmural pressure. Am J Physiol Heart Circ Physiol 2013; 305:H203-10. [PMID: 23666672 DOI: 10.1152/ajpheart.00677.2012] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
In vitro studies have revealed that acute increases in transmural pressure increase lymphatic vessel contractile function. However, adaptive responses to prolonged changes in transmural pressure in vivo have not been reported. Therefore, we developed a novel bovine mesenteric lymphatic partial constriction model to test the hypothesis that lymphatic vessels exposed to higher transmural pressures adapt functionally to become stronger pumps than vessels exposed to lower transmural pressures. Postnodal mesenteric lymphatic vessels were partially constricted for 3 days. On postoperative day 3, constricted vessels were isolated, and divided into upstream (UP) and downstream (DN) segment groups, and instrumented in an isolated bath. Although there were no differences between the passive diameters of the two groups, both diastolic diameter and systolic diameter were significantly larger in the UP group than in the DN group. The pump index of the UP group was also higher than that in the DN group. In conclusion, this is the first work to report how lymphatic vessels adapt to prolonged changes in transmural pressure in vivo. Our results suggest that vessel segments upstream of the constriction adapt to become both better fluid conduits and lymphatic pumps than downstream segments.
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Affiliation(s)
- R M Dongaonkar
- Michael E. DeBakey Institute, Texas A&M University, College Station, TX 77843-4466, USA
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Yang CW, Unanue ER. Neutrophils control the magnitude and spread of the immune response in a thromboxane A2-mediated process. ACTA ACUST UNITED AC 2013; 210:375-87. [PMID: 23337807 PMCID: PMC3570104 DOI: 10.1084/jem.20122183] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Neutrophil-produced thromboxane A2 controls the magnitude and spread of T cell responses to distal lymph nodes. Neutrophils are obligate cells entering lymph nodes shortly after immunization with protein antigens in adjuvants, starting during the first hour and continuing for several days in two distinct waves. Previously, we demonstrated the strong suppressive effects of neutrophils on CD4 T cell and B cell responses, using either neutrophil-depleting antibodies or genetically neutropenic mice. In this study, we find that neutrophils are the major cells controlling the spread of T cell responses to distal lymph nodes. Although in the presence of neutrophils, ∼75% of the response was restricted to the draining node, in their absence, most of the response was found in distal nodes. Prostanoids were responsible for the rapid entry of neutrophils into the draining nodes, as well as for the two distinct neutrophil effects: the modulation of the magnitude of the cellular response, and in its spread outside the draining nodes. Neutrophil-produced thromboxane A2 was the key eicosanoid controlling both effects. Adoptive transfer of neutrophils into mice genetically deficient in neutrophils indicated their role in both. These functions of neutrophils are important in infections and vaccinations with adjuvants where neutrophils are abundant in the initial stages.
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Affiliation(s)
- Chiao-Wen Yang
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA
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Multiscale Modelling of Lymphatic Drainage. MULTISCALE COMPUTER MODELING IN BIOMECHANICS AND BIOMEDICAL ENGINEERING 2013. [DOI: 10.1007/8415_2012_148] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Mihara M, Hara H, Hayashi Y, Narushima M, Yamamoto T, Todokoro T, Iida T, Sawamoto N, Araki J, Kikuchi K, Murai N, Okitsu T, Kisu I, Koshima I. Pathological steps of cancer-related lymphedema: histological changes in the collecting lymphatic vessels after lymphadenectomy. PLoS One 2012; 7:e41126. [PMID: 22911751 PMCID: PMC3404077 DOI: 10.1371/journal.pone.0041126] [Citation(s) in RCA: 192] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2012] [Accepted: 06/19/2012] [Indexed: 11/30/2022] Open
Abstract
Introduction To date, an electron microscopy study of the collecting lymphatic vessels has not been conducted to examine the early stages of lymphedema. However, such histological studies could be useful for elucidating the mechanism of lymphedema onset. The aim of this study was to clarify the changes occurring in collecting lymphatic vessels after lymphadenectomy. Methods The study was conducted on 114 specimens from 37 patients who developed lymphedema of the lower limbs after receiving surgical treatment for gynecologic cancers and who consulted the University of Tokyo Hospital and affiliated hospitals from April 2009 to March 2011. Lymphatic vessels that were not needed for lymphatico venous anastomosis surgery were trimmed and subsequently examined using electron microscopy and light microscopy. Results Based on macroscopic findings, the histochemical changes in the collecting lymphatic vessels were defined as follows: normal, ectasis, contraction, and sclerosis type (NECST). In the ectasis type, an increase in endolymphatic pressure was accompanied by a flattening of the lymphatic vessel endothelial cells. In the contraction type, smooth muscle cells were transformed into synthetic cells and promoted the growth of collagen fibers. In the sclerosis type, fibrous elements accounted for the majority of the components, the lymphatic vessels lost their transport and concentrating abilities, and the lumen was either narrowed or completely obstructed. Conclusions The increase in pressure inside the collecting lymphatic vessels after lymphadenectomy was accompanied by histological changes that began before the onset of lymphedema.
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Affiliation(s)
- Makoto Mihara
- Department of Plastic and Reconstructive Surgery, The University of Tokyo, Tokyo, Japan.
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Abstract
The recent advances in our understanding of lymphatic physiology and the role of the lymphatics in actively regulating fluid balance, lipid transport, and immune cell trafficking has been furthered in part through innovations in imaging, tissue engineering, quantitative biology, biomechanics, and computational modeling. Interdisciplinary and bioengineering approaches will continue to be crucial to the progression of the field, given that lymphatic biology and function are intimately woven with the local microenvironment and mechanical loads experienced by the vessel. This is particularly the case in lymphatic diseases such as lymphedema where the microenvironment can be drastically altered by tissue fibrosis and adipocyte accumulation. In this review we will highlight contributions engineering and mechanics have made to lymphatic physiology and will discuss areas that will be important for future research.
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Rahbar E, Moore JE. A model of a radially expanding and contracting lymphangion. J Biomech 2011; 44:1001-7. [PMID: 21377158 DOI: 10.1016/j.jbiomech.2011.02.018] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2010] [Revised: 02/15/2011] [Accepted: 02/16/2011] [Indexed: 10/18/2022]
Abstract
The lymphatic system is an extensive vascular network featuring valves and contractile walls that pump interstitial fluid and plasma proteins back to the main circulation. Immune function also relies on the lymphatic system's ability to transport white blood cells. Failure to drain and pump this excess fluid results in edema characterized by fluid retention and swelling of limbs. It is, therefore, important to understand the mechanisms of fluid transport and pumping of lymphatic vessels. Unfortunately, there are very few studies in this area, most of which assume Poiseuille flow conditions. In vivo observations reveal that these vessels contract strongly, with diameter changes of the order of magnitude of the diameter itself over a cycle that lasts typically 2-3s. The radial velocity of the contracting vessel is on the order of the axial fluid velocity, suggesting that modeling flow in these vessels with a Poiseuille model is inappropriate. In this paper, we describe a model of a radially expanding and contracting lymphatic vessel and investigate the validity of assuming Poiseuille flow to estimate wall shear stress, which is presumably important for lymphatic endothelial cell mechanotransduction. Three different wall motions, periodic sinusoidal, skewed sinusoidal and physiologic wall motions, were investigated with steady and unsteady parabolic inlet velocities. Despite high radial velocities resulting from the wall motion, wall shear stress values were within 4% of quasi-static Poiseuille values. Therefore, Poiseuille flow is valid for the estimation of wall shear stress for the majority of the lymphangion contractile cycle.
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Affiliation(s)
- Elaheh Rahbar
- Department of Biomedical Engineering, Texas A&M University, 337 Zachry Engineering Center, Mail Stop 3120, College Station, TX 77843-3120, USA
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27
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Dixon JB. Lymphatic lipid transport: sewer or subway? Trends Endocrinol Metab 2010; 21:480-7. [PMID: 20541951 PMCID: PMC2914116 DOI: 10.1016/j.tem.2010.04.003] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2010] [Revised: 04/29/2010] [Accepted: 04/30/2010] [Indexed: 12/17/2022]
Abstract
The lymphatics began receiving attention in the scientific community as early as 1622, when Gasparo Aselli noted the appearance of milky-white vessels in the mesentery of a well-fed dog. Since this time, the lymphatic system has been historically regarded as the sewer of the vasculature, passively draining fluid and proteins from the interstitial spaces (along with lipid from the gut) into the blood. Recent reports, however, suggest that the lymphatic role in lipid transport is an active and intricate process, and that when lymphatic function is compromised, there are systemic consequences to lipid metabolism and transport. This review highlights these recent findings, and suggests future directions for understanding the interplay between lymphatic and lipid biology in health and disease.
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Affiliation(s)
- J Brandon Dixon
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA.
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Venugopal AM, Stewart RH, Laine GA, Quick CM. Nonlinear lymphangion pressure-volume relationship minimizes edema. Am J Physiol Heart Circ Physiol 2010; 299:H876-82. [PMID: 20601461 DOI: 10.1152/ajpheart.00239.2009] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Lymphangions, the segments of lymphatic vessel between two valves, contract cyclically and actively pump, analogous to cardiac ventricles. Besides having a discernable systole and diastole, lymphangions have a relatively linear end-systolic pressure-volume relationship (with slope E(max)) and a nonlinear end-diastolic pressure-volume relationship (with slope E(min)). To counter increased microvascular filtration (causing increased lymphatic inlet pressure), lymphangions must respond to modest increases in transmural pressure by increasing pumping. To counter venous hypertension (causing increased lymphatic inlet and outlet pressures), lymphangions must respond to potentially large increases in transmural pressure by maintaining lymph flow. We therefore hypothesized that the nonlinear lymphangion pressure-volume relationship allows transition from a transmural pressure-dependent stroke volume to a transmural pressure-independent stroke volume as transmural pressure increases. To test this hypothesis, we applied a mathematical model based on the time-varying elastance concept typically applied to ventricles (the ratio of pressure to volume cycles periodically from a minimum, E(min), to a maximum, E(max)). This model predicted that lymphangions increase stroke volume and stroke work with transmural pressure if E(min) < E(max) at low transmural pressures, but maintain stroke volume and stroke work if E(min)= E(max) at higher transmural pressures. Furthermore, at higher transmural pressures, stroke work is evenly distributed among a chain of lymphangions. Model predictions were tested by comparison to previously reported data. Model predictions were consistent with reported lymphangion properties and pressure-flow relationships of entire lymphatic systems. The nonlinear lymphangion pressure-volume relationship therefore minimizes edema resulting from both increased microvascular filtration and venous hypertension.
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Affiliation(s)
- Arun M Venugopal
- Michael E. DeBakey Institute, Texas A&M University, College Station, Texas 77843-4466, USA
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