Contractility Of Lymphatic Vessels Research Articles

Numerical investigation on flow-induced wall shear stress variation of metastatic cancer cells in lymphatics with elastic valves

Hematogenous metastasis occurs when cancer cells detach from the extracellular matrix in the primary tumor into the bloodstream or lymphatic system. Elucidating the response of metastatic tumor cells in suspension to the flow conditions in lymphatics with valves from a mechanical/fluidic perspective is necessary. A physiologically relevant computational model of a lymphatic vessel with valves was constructed using fully coupled fluid–cell–vessel interactions to investigate the effects of lymphatic vessel contractility, valve properties, and cell size and stiffness on the variations in magnitude and gradient of the flow-induced wall shear stress (WSS) experienced by suspended tumor cells. Results indicated that the maximum WSSmax increased with the increments in cell diameter, vessel contraction amplitude, and valve stiffness. The decrease in vessel contraction period and valve aspect ratio also increased the maximum WSSmax. The influence of the properties of the valve on the WSS was more significant among the factors mentioned above. The maximum WSSmax acting on the cancer cell when the cell reversed the direction of its motion in the valve region increased by 0.5–1.4 times that before the cell entered the valve region. The maximum change in WSS was in the range of 0.004–0.028 Pa/µm depending on the factors studied. They slightly exceeded the values associated with breast cancer cell apoptosis. The results of this study provide biofluid mechanics-based support for mechanobiological research on the metastasis of metastatic cancer cells in suspension within the lymphatics.

Occlusion Pressure of the Thoracic Duct in Fontan Patients With Lymphatic Failure: Does Dilatation Challenge Contractility?

The Fontan circulation challenges the lymphatic system. Increasing production of lymphatic fluid and impeding lymphatic return, increased venous pressure may cause lymphatic dilatation and decrease lymphatic contractility. In-vitro studies have reported a lymphatic diameter-tension curve, with increasing passive stretch affecting the intrinsic contractile properties of each thoracic duct segment. We aimed to describe thoracic duct occlusion pressure and asses if thoracic duct dilation impairs contractility in individuals with a Fontan circulation and lymphatic failure. Central venous pressure and thoracic duct measurements were retrospectively collected from 31 individuals with a Fontan circulation. Thoracic duct occlusion pressure was assessed during a period of external manual compression and used as an indicator of lymphatic vessel contractility. Measurements of pressure were correlated with measurements of the thoracic duct diameter in images obtained by dynamic contrast-enhanced MR lymphangiography. The average central venous pressure and average pressure of the thoracic duct were 17 mm Hg. During manual occlusion, the thoracic duct pressure significantly increased to 32 mm Hg. The average thoracic duct diameter was 3.3 mm. Thoracic duct diameter correlated closely with the central venous pressure. The rise in pressure following manual occlusion showed an inverse correlation with the diameter of the thoracic duct. Higher central venous pressures are associated with increasing diameters of the thoracic duct. When challenged by manual occlusion, dilated thoracic ducts display a decreased ability to increase pressure. Dilatation and a resulting decreased contractility may partly explain the challenged lymphatic system in individuals with a Fontan circulation.

Effect of Rapamycin on Contractility of Lymphatic Vessel and Energy Metabolism of Lymphatic Muscle Cells

Proper functioning of lymphatic vessels (LV) is necessary for the transport of fluids, proteins, and metabolites from the interstitium via lymph nodes to the blood circulation. To achieve all these functions, lymphatic vessels use muscle cells for contractions and endothelial cells to precisely tune these contractions. Moreover, lymphatic vessels play important roles in antigen and immune cell trafficking to provide sufficient immune responses. During a solid organ transplantation, the body's immune system has a strong tendency to reject the organ transplant. Therefore, immunosuppressive drugs are used for tolerance induction to lower the activity of the immune system to accept the organ transplant. Rapamycin is a potent immunosuppressant that can disrupt cytokine signaling, which contributes to the proliferation of lymphocytes. Potential but unusual side effects of using Rapamycin include lymphatic disorders. Several cases were observed wherein transplant recipients exhibited delayed drainage of lymph, lymphatic obstruction, and complete blockage of lymphatic vessels. Cases such as these suggest that more research must be conducted to investigate the mechanism of these effects and possible prophylaxis and treatment of these complications. We investigated the effect of rapamycin on contractility of rat mesenteric lymphatic vessels and lymphatic muscle cell (LMC) metabolism. Rapamycin at 10^-5M after 1Hr of application decreased tone of LV at transmural pressure of 1cm H2O by 4.1 ± 2.9%, and decreased contractile amplitude by 7.8 ± 3.5% and 10.2 ± 4.2% at pressures 3 and 5 cm H2O respectively. Rapamycin at 10^-5M after 1Hr of application decreased LMC ATP production by 0.012 ± 0.002 pmol/min/ug, maximal oxygen consumption rate by 0.027 ± 0.006 pmol/min/ug, spare mitochondrial capacity by 0.025 ± 0.005 pmol/min/ug, coupling efficiency by 33.9 ± 6.1% and increased proton leak by 0.009 ± 0.002 pmol/min/ug. Rapamycin also increased basal extracellular acidification rate (ECAR) by 0.011 ± 0.003 pmol/min/ug. Therefore, rapamycin in high concentration could possibly lead to mitochondrial uncoupling that might reflect changes in contractility. Moreover, an increase in the ECAR can indicate shifting glucose fermentation to lactate that could progress to pathological LV remodeling in the future.

Differential effects of anaesthesia on the contractility of lymphatic vessels in vivo: authors’ reply

Differential effects of anaesthesia on the contractility of lymphatic vessels <i>in vivo</i>: authors’ reply

Methicillin‐resistant Staphylococcus aureus causes sustained collecting lymphatic vessel dysfunction

Methicillin‐resistant Staphylococcus aureus (MRSA) is a major cause of morbidity and mortality worldwide and is a frequent cause of skin and soft tissue infections (SSTIs). Lymphedema—fluid accumulation in tissue caused by impaired lymphatic vessel function—is a strong risk factor for SSTIs. SSTIs also frequently recur in patients and sometimes lead to acquired lymphedema. However, the mechanism of how SSTIs can be both the consequence and the cause of lymphatic vessel dysfunction is not known.Here, we used the endemic USA300 strain of community‐associated MRSA (CA‐MRSA), a common cause of serious bacterial infections in the United States, to establish a model of localized MRSA infection. We used intravital imaging to determine whether MRSA infections inhibit lymphatic vessel contractility and lymph flow. In vivo studies used C57BL/6, iNOS−/− C57BL/6, MyD88−/− C57BL/6, LysMgfp/gfp C57BL/6, and alpha SMAP‐DsRed/C57BL/6 mice to assess the effects of host‐derived molecules to lymphatic contractility after infection. Alpha SMA‐DsRed transgenic mice were visualized and immunofluorescence staining of alpha SMA+ lymphatic muscle cells (LMCs) of WT mice was performed to analyze LMC coverage of lymphatic vessels on multiple days after infection. To define the molecular mechanisms related to this response, we performed cell viability and cell lysis assays and measured killing of LMCs by MRSA‐conditioned supernatant from wild type and mutant MRSA strain(s). Similar experiments were performed using recombinant MRSA toxins.Intravital imaging in mice revealed an acute reduction in both lymphatic vessel contractility and lymph flow after localized MRSA infection. Moreover, chronic lymphatic impairment is observed long after MRSA is cleared and inflammation is resolved. Associated with decreased collecting lymphatic vessel function was the loss and disorganization of lymphatic muscle cells (LMCs), which are critical for lymphatic contraction. In vitro, incubation with MRSA‐conditioned supernatant led to LMC death. Proteomic analysis identified several accessory gene regulator (agr)–controlled MRSA exotoxins that contribute to LMC death. Infection with agr mutant MRSA resulted in sustained lymphatic function compared to animals infected with wild‐type MRSA.Our findings suggest that agr is a promising target to preserve lymphatic vessel function and promote immunity during SSTIs.Support or Funding InformationThis work was supported by the National Institutes of Health under award numbers R21AI097745, DP2OD008780, R01CA214913, and R01HL128168 to Timothy Padera. Dennis Jones was supported in part by the UNCF‐Merck Science Initiative Postdoctoral Fellowship, Burroughs Wellcome Fund Postdoctoral Enrichment Program Award, and NIH NCI F32CA183465.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Differential effects of anaesthesia on the contractility of lymphatic vessels in vivo.

Contractility of lymphatic collectors is essential for the functionality of the lymphatic system and, thus, for lymph flow. Previously published rates of lymphatic collectors in mice vary from 1.1 to 17 contractions/min with little agreement between investigators. In this study, we focused on the effects of different anaesthesia regimens on lymphatic vessel contractility using in vivo imaging approaches. We show that isoflurane and pentobarbital have an inhibitory effect on lymphatic contractility compared to mice under other anaesthesia regimens and in awake conditions. These results should help to establish a standardization of lymphatic contraction studies in mice and may also have relevance for patients undergoing anaesthesia during surgery. Contractions of collecting lymphatic vessels are essential for the function of the lymphatic vascular system, due to the lack of a central pump to drive flow. A wide range of physiological contraction frequencies and strengths have been reported in previous in vivo studies in mice. This is probably due to the different types of anaesthesia that have been used and which might have exerted direct influences on lymphatic vessel function. We investigated six commonly used anaesthesia regimens for their influence on lymphatic vessel contractility using near-infrared in vivo imaging approaches. Non-invasive imaging of the lymphatic leg collector revealed distinct effects of the anaesthesia regimens with reduced contraction activity under isoflurane and pentobarbital anaesthesia. Isoflurane also reduced the contractility of near-infrared dye-loaded vessels during invasive imaging of the lymphatic flank collector whereas the combination of ketamine/xylazine/acepromazine had no major effects. The transport time of a lymphatic-specific dye from the skin through the lymphatic vasculature to the systemic bloodstream was also delayed under isoflurane anaesthesia. Based on these results, we recommend use of combinations of ketamine and medetomidine for future non-invasive studies and of ketamine, xylazine and acepromazine for invasive studies. Beyond their importance for facilitating the interpretation and planning of animal studies, our findings might also have relevance for human patients undergoing anaesthesia for surgical procedures.

Methicillin-resistant Staphylococcus aureus causes sustained collecting lymphatic vessel dysfunction.

Methicillin-resistant Staphylococcus aureus (MRSA) is a major cause of morbidity and mortality worldwide and is a frequent cause of skin and soft tissue infections (SSTIs). Lymphedema-fluid accumulation in tissue caused by impaired lymphatic vessel function-is a strong risk factor for SSTIs. SSTIs also frequently recur in patients and sometimes lead to acquired lymphedema. However, the mechanism of how SSTIs can be both the consequence and the cause of lymphatic vessel dysfunction is not known. Intravital imaging in mice revealed an acute reduction in both lymphatic vessel contractility and lymph flow after localized MRSA infection. Moreover, chronic lymphatic impairment is observed long after MRSA is cleared and inflammation is resolved. Associated with decreased collecting lymphatic vessel function was the loss and disorganization of lymphatic muscle cells (LMCs), which are critical for lymphatic contraction. In vitro, incubation with MRSA-conditioned supernatant led to LMC death. Proteomic analysis identified several accessory gene regulator (agr)-controlled MRSA exotoxins that contribute to LMC death. Infection with agr mutant MRSA resulted in sustained lymphatic function compared to animals infected with wild-type MRSA. Our findings suggest that agr is a promising target to preserve lymphatic vessel function and promote immunity during SSTIs.

Temporal Dynamics of the Rat Thoracic Duct Contractility in the Presence of Imposed Flow.

The initial periods of increased flow inside lymphatic vessels demonstrate specific temporary patterns of self-tuning of lymphatic vessel contractility that are heterogeneous across regional lymphatic networks. The current literature primarily refers to the immediate and fast reactions of the lymphangions to increases in basal flow. Until now, there were no available data on how the lymphatic vessels react to comparatively longer periods of imposed flow. In this study, we measured and analyzed the contractility of the rat thoracic duct segments, isolated, cannulated, and pressurized at 3 cm H2O at no imposed flow conditions and during 4 hours of imposed flow (constant transaxial pressure gradient of 2 cm H2O). We found the development of a progressing lymphatic tonic relaxation and inhibition of the lymphatic contraction frequency over 4 hours of imposed flow. After a short initial decrease, lymphatic phasic contraction amplitude rose significantly during the first hour of imposed flow, and it demonstrated a trend to return toward control levels after 3 hours of imposed flow. As a result, the fractional pump flow (active lymph pumping per minute) of isolated thoracic duct segments reached and maintained a statistically significant decrease (from control no-flow conditions) at the end of the third hour of imposed flow. Our new findings provide a better understanding of how lymphatic contractility changes during the development of prolonged periods of steady lymph flow. The latter may occur during the initial phases of development of an inflammatory-related tissue edema.

In vivo visualization and quantification of collecting lymphatic vessel contractility using near-infrared imaging.

Techniques to image lymphatic vessel function in either animal models or in the clinic are limited. In particular, imaging methods that can provide robust outcome measures for collecting lymphatic vessel function are sorely needed. In this study, we aimed to develop a method to visualize and quantify collecting lymphatic vessel function in mice, and to establish an in vivo system for evaluation of contractile agonists and antagonists using near-infrared fluorescence imaging. The flank collecting lymphatic vessel in mice was exposed using a surgical technique and a near-infrared tracer was infused into the inguinal lymph node. Collecting lymphatic vessel contractility and valve function could be easily visualized after the infusion. A diameter tracking method was established and the diameter of the vessel was found to closely correlate to near-infrared fluorescence signal. Phasic contractility measures of frequency and amplitude were established using an automated algorithm. The methods were validated by tracking the vessel response to topical application of a contractile agonist, prostaglandin F2α, and by demonstrating the potential of the technique for non-invasive evaluation of modifiers of lymphatic function. These new methods will enable high-resolution imaging and quantification of collecting lymphatic vessel function in animal models and may have future clinical applications.

Colonic Insult Impairs Lymph Flow, Increases Cellular Content of the Lymph, Alters Local Lymphatic Microenvironment, and Leads to Sustained Inflammation in the Rat Ileum.

Lymphatic dysfunction has been linked to inflammation since the 1930s. Lymphatic function in the gut and mesentery is grossly underexplored in models of inflammatory bowel disease despite the use of lymphatic occlusion in early models of inflammatory bowel disease. Activation of the innate and adaptive immune system is a hallmark of TNBS-induced inflammation and is linked to disruption of the intrinsic lymph pump. Recent identification of crosstalk between lymphatic vessel resident immune cells and regulation of lymphatic vessel contractility underscore the importance of the timing of lymphatic dysfunction during tissue inflammation in response to TNBS. To evaluate lymphatic function in TNBS induced inflammation, lymph was collected and flow measured from mesenteric lymphatics. Cellularity and cytokine profile of the lymph was also measured. Histopathology was performed to determine severity of injury and immunofluorescent staining of the mesentery was done to evaluate changes in the population of immune cells that reside near and on gastro-intestinal collecting lymphatics. Lymph transport fell 24 hours after TNBS administration and began recovering at 72 hours. Significant reduction of lymph flow preceded significant increase in histopathological score and occurred simultaneously with increased myeloperoxidase activity. These changes were preceded by increased MHCII cells surrounding mesenteric lymphatics leading to an altered lymphatic environment that would favor dysfunction. Alterations in environmental factors that effect lymphatic function occur before the development of gross GI inflammation. Reduced lymphatic function in TNBS-mediated inflammation is likely an early factor in the development of injury and that recovery of function is associated with resolution of inflammation.

The contribution of K(+) channels to human thoracic duct contractility.

In smooth muscle cells, K(+) permeability is high, and this highly influences the resting membrane potential. Lymph propulsion is dependent on phasic contractions generated by smooth muscle cells of lymphatic vessels, and it is likely that K(+) channels play a critical role in regulating contractility in this tissue. The aim of this study was to investigate the contribution of distinct K(+) channels to human lymphatic vessel contractility. Thoracic ducts were harvested from 43 patients and mounted in a wire myograph for isometric force measurements or membrane potential recordings with an intracellular microelectrode. Using K(+) channel blockers and activators, we demonstrate a functional contribution to human lymphatic vessel contractility from all the major classes of K(+) channels [ATP-sensitive K(+) (KATP), Ca(2+)-activated K(+), inward rectifier K(+), and voltage-dependent K(+) channels], and this was confirmed at the mRNA level. Contraction amplitude, frequency, and baseline tension were altered depending on which channel was blocked or activated. Microelectrode impalements of lymphatic vessels determined an average resting membrane potential of -43.1 ± 3.7 mV. We observed that membrane potential changes of <5 mV could have large functional effects with contraction frequencies increasing threefold. In general, KATP channels appeared to be constitutively open since incubation with glibenclamide increased contraction frequency in spontaneously active vessels and depolarized and initiated contractions in previously quiescent vessels. The largest change in membrane voltage was observed with the KATP opener pinacidil, which caused 24 ± 3 mV hyperpolarization. We conclude that K(+) channels are important modulators of human lymphatic contractility.

Molecular and cellular basis of the regulation of lymphatic contractility and lymphatic absorption

Lymphatic absorption is a highly regulated process driven by both an extrinsic mechanism (external force) and an intrinsic mechanism (lymphatic vessel contractility). The lymphatic muscle is a specialized smooth muscle with unique mechanical properties. To understand the molecular mechanism and relative contribution of smooth muscle contraction in lymphatic absorption, we analyzed mice with a smooth muscle-specific deletion of Mylk, a critical gene for smooth muscle contraction. Interestingly, the knockout mice were significantly resistant to anesthesia reagents. Upon injection in the feet with FITC-dextran, the mutant mice displayed a 2-fold delay of the absorption peak in the peripheral circulation. Examining the ear lymphatic vessels of the mutant mice revealed a reduction in the amount of fluid in the lumens of the lymphangions, suggesting an impairment of lymph formation. The Mylk-deficient lymphatic muscle exhibited a significant reduction of peristalsis and of myosin light chain phosphorylation in response to depolarization. We thus concluded that MLCK and myosin light chain phosphorylation are required for lymphatic vessel contraction. Lymphatic contractility is not an exclusive requirement for lymphatic absorption, and external force appears to be necessary for absorption.

Contractile behavior of the uterine lymphatic vessels

While various lymphatic vessels networks are shown to adapt their contractility to changes in wall stretch and wall shear stress, until now, little is known on physiological characteristics of uterine lymphatic vessels (LV) in both the non‐pregnant and pregnant uterus. In this study we for the first time performed detailed evaluation of the contractile characteristics of the collecting uterine LV from ~250 g female non‐pregnant Sprague‐Dawley rats. Changes in lymphatic diameter were recorded with their subsequent analysis and calculation of the lymphatic pump indices of isolated, cannulated and pressurized rat uterine LV at different ranges of pressure and imposed flow in control conditions and after L‐NAME application. We found, that pressure stimulates contractility of rat uterine LV with contraction amplitude and pumping maximum at 1 cm H2O, while contraction frequency is almost stretch‐insensitive. NO had only a minor involvement in this regulation. These vessels also demonstrated a minor imposed‐flow/ wall shear stress‐dependent inhibition of tone, contraction amplitude and pump flow, but not contraction frequency. L‐NAME did not eliminate this flow/shear dependency, but induced flow‐independent shifts of all parameters of contractility of these vessels. In summary, our preliminary data show that uterine LV possesses unique contractile patterns different from other regional LV. NIH RO1 HL‐070308

The effect of acute progestational hypoxia on ECG parameters and contractility of lymphatic vessels in mature white rats

Acute progestational hypoxia induced hyperactivity with low anxiety level and bradycardia in female descendants only. The experimental males demonstrated a significant increase in the duration and frequency of contractions of lymphatic vessels following NE application, while females showed no difference compared to the control.

Endothelin-mediated constriction of prenodal lymphatic vessels in the canine forelimb

Endothelin is a 21 amino acid peptide which is produced by the vascular endothelium and is believed to be the mediator of endothelium-dependent vasoconstriction. In the current study we assessed the ability of synthetic human endothelin-1 to affect prenodal lymphatic vessel contractility in the canine forelimb. Intralymphatic infusion of endothelin at 1.09 · 10 −9, 1.09 · 10 −8 and 1.09 · 10 −7 M significantly constricted lymphatic vessels as evidenced by dose-dependent increases in lymphatic perfusion pressure. The increase in lymphatic perfusion pressure seen during intralymphatic infusion of endothelin at 1.09 · 10 −8 M during the intra-arterial infusion of phentolamine was not significantly different from that seen prior to phentolamine, indicating that endothelin-mediated lymphatic constriction is not α-receptor mediated. Intra-arterial infusion of endothelin at three infusion rates significantly increased forelimb arterial, systemic and lymphatic perfusion pressures. The constriction seen when endothelin (1.09 · 10 −8 M) was infused intralymphatically in the intact lymphatic system was not significantly different from that observed when only the prenodal lymph vessel was perfused. This indicated that the lymph nodes and efferent lymph vessels do not contribute significantly to the lymphatic constriction produced by endothelin. These data are consistent with the hypothesis that endothelin may modulate lymphatic function under either normal or pathophysiological conditions.

Perfused prenodal lymphatics are constricted by prostaglandins

Prostaglandins may contribute to the control of lymph flow by affecting lymphatic vessel contractility. We measured the pressure in perfused prenodal lymphatic vessel in the paw of the anesthetized dog as affected by administration of prostaglandins E1, E2, F2 alpha or arachidonic acid. The forelimb was perfused at constant flow with blood obtained from a femoral artery. Systemic arterial, central venous, and forelimb vascular pressures were measured. When added to the lymphatic perfusate, all of the prostaglandins and arachidonic acid caused constriction of lymphatic vessels. Perfusion of prenodal lymphatics separated from downstream nodes and vessels showed that this constriction occurred primarily in prenodal vessels. However, only prostaglandin F2 alpha caused lymphatic constriction when infused into the blood to the forelimb. Because prostaglandins are a common component of the lymph leaving an area of tissue damage, these results are compatible with the possibility that prostaglandins, by directly affecting lymphatics, help modulate lymph flow following local injury.