Lymphatic Vessels: The Next Frontier in Lung Transplant

Effect of Semaglutide and Empagliflozin on Pulmonary Structure and Proteomics in Obese Mice

Objective

This study utilized proteomics to investigate changes in protein expression associated with lung health in obese mice exposed to semaglutide and empagliflozin through a high-fat diet.

Methods

Twenty-eight male C57BL/6JC mice were randomly assigned to two groups: a control diet group (n = 7) and a high-fat diet group (n = 21). The HFD group was further divided into three groups: HFD group (n = 7), Sema group (n = 7), and Empa group (n = 7). Post-treatment, mice underwent assessments including glucose tolerance, lipids, oxidative stress markers, body weight, lung weight, and structure. Proteomics identified differentially expressed proteins (DEPs) in lung tissue, and bioinformatics analyzed the biological processes and functions of these proteins.

Results

Semaglutide and empagliflozin significantly attenuated obesity-induced hyperglycemia, abnormal lipid metabolism, oxidative stress response, and can decrease alveolar wall thickness, enlarge alveolar lumen, and reduce collagen content in lung tissue. Both medications also attenuated lung elastic fibre cracking and disintegration. In the HFD/NCD group, there were 66 DEPs, comprising 30 proteins that were increased and 36 that were decreased. Twenty-three DEPs overlapped between Sema/HFD and Empa/HFD, with 11 up-regulated and 12 down-regulated simultaneously. After analysing DEPs in different groups, four proteins - LYVE1, BRAF, RGCC, and CHMP5 - were all downregulated in the HFD group and upregulated by semaglutide and empagliflozin treatment.

Conclusion

This study demonstrates that obesity induced by a high-fat diet causes a reduction in the expression of LYVE1, BRAF, RGCC, and CHMP5 proteins, potentially affecting lung function and structure in mice. Significantly, the administration of semaglutide and empagliflozin elevates the levels of these proteins, potentially offering therapeutic benefits against lung injury caused by obesity. Merging semaglutide with empagliflozin may exert a more pronounced impact.

Role of the interstitium during septic shock: a key to the understanding of fluid dynamics?

BACKGROUND

While not traditionally included in the conceptual understanding of circulation, the interstitium plays a critical role in maintaining fluid homeostasis. Fluid balance regulation is a critical aspect of septic shock, with a well-known association between fluid balance and outcome. The regulation of transcapillary flow is the first key to understand fluid homeostasis during sepsis.

MAIN TEXT

Capillary permeability is increased during sepsis, and was classically considered to be necessary and sufficient to explain the increase of capillary filtration during inflammation. However, on the other side of the endothelial wall, the interstitium may play an even greater role to drive capillary leak. Indeed, the interstitial extracellular matrix forms a complex gel-like structure embedded in a collagen skeleton, and has the ability to directly attract intravascular fluid by decreasing its hydrostatic pressure. Thus, interstitium is not a mere passive reservoir, as was long thought, but is probably major determinant of fluid balance regulation during sepsis. Up to this date though, the role of the interstitium during sepsis and septic shock has been largely overlooked. A comprehensive vision of the interstitium may enlight our understanding of septic shock pathophysiology. Overall, we have identified five potential intersections between septic shock pathophysiology and the interstitium: 1. increase of oedema formation, interacting with organ function and metabolites diffusion; 2. interstitial pressure regulation, increasing transcapillary flow; 3. alteration of the extracellular matrix; 4. interstitial secretion of inflammatory mediators; 5. decrease of lymphatic outflow.

CONCLUSIONS

We aimed at reviewing the literature and summarizing the current knowledge along these specific axes, as well as methodological aspects related to interstitium exploration.

The lymphatic vasculature in lung function and respiratory disease

The lymphatic vasculature maintains tissue homeostasis via fluid drainage in the form of lymph and immune surveillance due to migration of leukocytes through the lymphatics to the draining lymph nodes. Lymphatic endothelial cells (LECs) form the lymphatic vessels and lymph node sinuses and are key players in shaping immune responses and tolerance. In the healthy lung, the vast majority of lymphatic vessels are found along the bronchovascular structures, in the interlobular septa, and in the subpleural space. Previous studies in both mice and humans have shown that the lymphatics are necessary for lung function from the neonatal period through adulthood. Furthermore, changes in the lymphatic vasculature are observed in nearly all respiratory diseases in which they have been analyzed. Recent work has pointed to a causative role for lymphatic dysfunction in the initiation and progression of lung disease, indicating that these vessels may be active players in pathologic processes in the lung. However, the mechanisms by which defects in lung lymphatic function are pathogenic are understudied, leaving many unanswered questions. A more comprehensive understanding of the mechanistic role of morphological, functional, and molecular changes in the lung lymphatic endothelium in respiratory diseases is a promising area of research that is likely to lead to novel therapeutic targets. In this review, we will discuss our current knowledge of the structure and function of the lung lymphatics and the role of these vessels in lung homeostasis and respiratory disease.

Alterations in Pulmonary Physiology with Lung Transplantation

Lung transplant is a treatment option for patients with end-stage lung diseases; however, survival outcomes continue to be inferior when compared to other solid organs. We review the several anatomic and physiologic changes that result from lung transplantation surgery, and their role in the pathophysiology of common complications encountered by lung recipients. The loss of bronchial circulation into the allograft after transplant surgery results in ischemia-related changes in the bronchial artery territory of the allograft. We discuss the role of bronchopulmonary anastomosis in blood circulation in the allograft posttransplant. We review commonly encountered complications related to loss of bronchial circulation such as allograft airway ischemia, necrosis, anastomotic dehiscence, mucociliary dysfunction, and bronchial stenosis. Loss of dual circulation to the lung also increases the risk of pulmonary infarction with acute pulmonary embolism. The loss of lymphatic drainage during transplant surgery also impairs the management of allograft interstitial fluid, resulting in pulmonary edema and early pleural effusion. We discuss the role of lymphatic drainage in primary graft dysfunction. Besides, we review the association of late posttransplant pleural effusion with complications such as acute rejection. We then review the impact of loss of afferent and efferent innervation from the allograft on control of breathing, as well as lung protective reflexes. We conclude with discussion about pulmonary function testing, allograft monitoring with spirometry, and classification of chronic lung allograft dysfunction phenotypes based on total lung capacity measurements. We also review factors limiting physical exercise capacity after lung transplantation, especially impairment of muscle metabolism. © 2023 American Physiological Society. Compr Physiol 13:4269-4293, 2023.

Critical Care Management Following Lung Transplantation

Postoperative critical care management for lung transplant recipients in the intensive care unit (ICU) has expanded in recent years due to its complexity and impact on clinical outcomes. The practical aspects of post-transplant critical care management, especially regarding ventilation and hemodynamic management during the early postoperative period in the ICU, are discussed in this brief review. Monitoring in the ICU provides information on the patient’s clinical status, diagnostic assessment of complications, and future management plans since lung transplantation involves unique pathophysiological conditions and risk factors for complications. After lung transplantation, the grafts should be appropriately ventilated with lung protective strategies to prevent ventilator-induced lung injury, as well as to promote graft function and maintain adequate gas exchange. Hypotension and varying degrees of pulmonary edema are common in the immediate postoperative lung transplantation setting. Ventricular dysfunction in lung transplant recipients should also be considered. Therefore, adequate volume and hemodynamic management with vasoactive agents based on their physiological effects and patient response are critical in the early postoperative lung transplantation period. Integrated management provided by a professional multidisciplinary team is essential for the critical care management of lung transplant recipients in the ICU.

Molecular Mechanisms Driving Lymphedema and Other Lymphatic Anomalies

Lymphatic vasculature regulates fluid homeostasis by absorbing interstitial fluid and returning it to blood. Lymphatic vasculature is also critical for lipid absorption and inflammatory response. Lymphatic vasculature is composed of lymphatic capillaries, collecting lymphatic vessels, lymphatic valves, and lymphovenous valves. Defects in any of these structures could lead to lymphatic anomalies such as lymphedema, cystic lymphatic malformation, and Gorham-Stout disease. Basic research has led to a deeper understanding of the stepwise development of the lymphatic vasculature. VEGF-C and shear stress signaling pathways have evolved as critical regulators of lymphatic vascular development. Loss-of-function and gain-of-function mutations in genes that are involved in these signaling pathways are associated with lymphatic anomalies. Importantly, drugs that target these molecules are showing outstanding efficacy in treating certain lymphatic anomalies. In this article, we summarize these exciting developments and highlight the future challenges.

A census of the lung: CellCards from LungMAP

The human lung plays vital roles in respiration, host defense, and basic physiology. Recent technological advancements such as single-cell RNA sequencing and genetic lineage tracing have revealed novel cell types and enriched functional properties of existing cell types in lung. The time has come to take a new census. Initiated by members of the NHLBI-funded LungMAP Consortium and aided by experts in the lung biology community, we synthesized current data into a comprehensive and practical cellular census of the lung. Identities of cell types in the normal lung are captured in individual cell cards with delineation of function, markers, developmental lineages, heterogeneity, regenerative potential, disease links, and key experimental tools. This publication will serve as the starting point of a live, up-to-date guide for lung research at https://www.lungmap.net/cell-cards/. We hope that Lung CellCards will promote the community-wide effort to establish, maintain, and restore respiratory health.

Acute Respiratory Distress Syndrome: Focus on Viral Origin and Role of Pulmonary Lymphatics

Acute respiratory distress syndrome (ARDS) is a serious affection of the lung caused by a variety of pathologies. Great interest is currently focused on ARDS induced by viruses (pandemic influenza and corona viruses). The review describes pulmonary changes in ARDS and specific effects of the pandemic viruses in ARDS, and summarizes treatment options. Because the known pathogenic mechanisms cannot explain all aspects of the syndrome, the contribution of pulmonary lymphatics to the pathology is discussed. Organization and function of lymphatics in a healthy lung and in resorption of pulmonary edema are described. A future clinical trial may provide more insight into the role of hyaluronan in ARDS but the development of promising pharmacological treatments is unlikely because drugs play no important role in lymphedema therapy.

The lymphatics in kidney health and disease

The mammalian vascular system consists of two networks: the blood vascular system and the lymphatic vascular system. Throughout the body, the lymphatic system contributes to homeostatic mechanisms by draining extravasated interstitial fluid and facilitating the trafficking and activation of immune cells. In the kidney, lymphatic vessels exist mainly in the kidney cortex. In the medulla, the ascending vasa recta represent a hybrid lymphatic-like vessel that performs lymphatic-like roles in interstitial fluid reabsorption. Although the lymphatic network is mainly derived from the venous system, evidence supports the existence of lymphatic beds that are of non-venous origin. Following their development and maturation, lymphatic vessel density remains relatively stable; however, these vessels undergo dynamic functional changes to meet tissue demands. Additionally, new lymphatic growth, or lymphangiogenesis, can be induced by pathological conditions such as tissue injury, interstitial fluid overload, hyperglycaemia and inflammation. Lymphangiogenesis is also associated with conditions such as polycystic kidney disease, hypertension, ultrafiltration failure and transplant rejection. Although lymphangiogenesis has protective functions in clearing accumulated fluid and immune cells, the kidney lymphatics may also propagate an inflammatory feedback loop, exacerbating inflammation and fibrosis. Greater understanding of lymphatic biology, including the developmental origin and function of the lymphatics and their response to pathogenic stimuli, may aid the development of new therapeutic agents that target the lymphatic system.

Intragraft Hyaluronan Increases in Association With Acute Lung Transplant Rejection

Supplemental Digital Content is available in the text.

Background.

Acute perivascular rejection (AR) is common in lung recipients and increases the risk for chronic lung allograft dysfunction (CLAD). Hyaluronan (HA), an extracellular matrix constituent, accumulates in experimental AR and can act as an innate immune agonist, breaking tolerance and potentiating alloimmunity. We previously demonstrated HA accumulates in CLAD after human-lung transplantation. We sought to determine if HA accumulates in the bronchoalveolar lavage fluid (BALF) concurrent with AR in lung recipients.

Methods.

The cohort consisted of 126 first adult lung recipients at 5 transplant centers with a total of 373 BALF samples collected within the first posttransplant year. All samples were paired with a lung biopsy from the same bronchoscopy. BALF HA (ng/mL) was quantified by ELISA and log-transformed for analysis. Linear-mixed effect models, adjusted for potential confounders, were used to estimate the association between BALF HA concentration and the presence of AR on biopsy. The association between early posttransplant BALF HA levels and the development of CLAD was explored utilizing tertiles of maximum BALF HA level observed within the first 6 months of transplant.

Results.

In analyses adjusted for potential confounders, BALF HA concentration was significantly increased in association with AR (change in means on log-scale 0.31; 95% CI, 0.01-0.60; P = 0.044). When considered on the original scale (ng/mL), BALF HA concentrations were 1.36 times (36%) higher, on average, among samples with, versus without, AR. The cumulative incidence of CLAD was numerically higher in individuals in the highest tertiles of BALF HA level within the first 6 months after transplant, as compared with those in the lowest tertile; however, this difference was not statistically significant (P = 0.32).

Conclusions.

These results demonstrate accumulation of HA in clinical AR and suggest a mechanism by which innate and adaptive immune activation might interact in the development of AR and CLAD.

Biochemical and mechanical signals in the lymphatic vasculature

Lymphatic vasculature is an integral part of the cardiovascular system where it maintains interstitial fluid balance. Additionally, lymphatic vasculature regulates lipid assimilation and inflammatory response. Lymphatic vasculature is composed of lymphatic capillaries, collecting lymphatic vessels and valves that function in synergy to absorb and transport fluid against gravitational and pressure gradients. Defects in lymphatic vessels or valves leads to fluid accumulation in tissues (lymphedema), chylous ascites, chylothorax, metabolic disorders and inflammation. The past three decades of research has identified numerous molecules that are necessary for the stepwise development of lymphatic vasculature. However, approaches to treat lymphatic disorders are still limited to massages and compression bandages. Hence, better understanding of the mechanisms that regulate lymphatic vascular development and function is urgently needed to develop efficient therapies. Recent research has linked mechanical signals such as shear stress and matrix stiffness with biochemical pathways that regulate lymphatic vessel growth, patterning and maturation and valve formation. The goal of this review article is to highlight these innovative developments and speculate on unanswered questions.

Characteristics and clinical implications of pleural effusions after lung transplantation: A retrospective analysis of 195 thoracocenteses in 113 patients

Despite advances in lung transplantation (LTx), morbidity, and mortality are high. We hypothesized that pleural effusions requiring thoracocentesis lead to poor outcomes after LTx. We performed a single-center retrospective analysis of thoracocenteses after initial hospital discharge in LTx patients between March 2008 and September 2020 to identify risk factors, etiologies, and outcomes. Of the 1223 patients included, 113 patients (9.2%) required a total of 195 thoracocenteses. The cumulative incidence of thoracocentesis was 10.6% at 1 year and 14.2% at 5 years after transplantation. We observed a bimodal distribution of pleural effusion onset with a threshold at 6 months. Late-onset effusions were mostly of malignant or cardiac origin. We observed a high rate of nonspecific effusions (41.5%) irrespective of the timepoint post-transplantation. Patients with late-onset effusions had significantly lower survival compared to a matched controlled group (HR 2.43; 95% CI (1.27-4.62). All pulmonary function parameters were significantly decreased in patients requiring thoracocentesis compared to matched controls. Male sex and re-transplantation were risk factors for pleural effusions. In conclusion, pleural effusions requiring thoracocentesis occur frequently in LTx patients and lead to a reduced long-term allograft function. Late-onset effusions are associated with a lower survival.

Inflammation in Pulmonary Arterial Hypertension

Pulmonary artery hypertension (PAH) is a devastating cardiopulmonary disease characterized by vascular remodeling and obliteration of the precapillary pulmonary arterioles. Alterations in the structure and function of pulmonary vessels result in the resistance of blood flow and can progress to right-sided heart failure, causing significant morbidity and mortality. There are several types of PAH, and the disease can be familial or secondary to an underlying medical condition such as a connective tissue disorder or infection. Regardless of the cause, the exact pathophysiology and cellular interactions responsible for disease development and progression are largely unknown.There is significant evidence to suggest altered immune and vascular cells directly participate in disease progression. Inflammation has long been hypothesized to play a vital role in the development of PAH, as an altered or skewed immune response favoring a proinflammatory environment that can lead to the infiltration of cells such as lymphocytes, macrophages, and neutrophils. Current treatment strategies focus on the dilation of partially occluded vessels; however, such techniques have not resulted in an effective strategy to reverse or prevent vascular remodeling. Therefore, current studies in human and animal models have attempted to understand the underlying pathophysiology of pulmonary hypertension (PH), specifically focusing on the inflammatory cascade predisposing patients to disease so that better therapeutic targets can be developed to potentially reverse or prevent disease progression.The purpose of this chapter is to provide a comprehensive review of the expanding literature on the inflammatory process that participates in PH development while highlighting important and current studies in both animal and human models. While our primary focus will be on cells found in the adaptive and innate immune system, we will review all potential causes of PAH, including cells of the endothelium, pulmonary lymphatics, and genetic mutations predisposing patients. In addition, we will discuss current therapeutic options while highlighting potential future treatments and the questions that still remain unanswered.

Donor-host Lymphatic Anastomosis After Murine Lung Transplantation

BACKGROUND

Establishing lung lymphatic drainage is thought to be important for successful lung transplantation. To date, there has been a complete absence of knowledge of how lymphatic connections are reestablished after lung transplant, despite evidence suggesting that this does indeed occur. The present study aimed to elucidate whether and how lymphatic anastomosis occurs after lung transplant.

METHODS

An orthotopic murine model of lung transplant using lymphatic reporter mice and whole mount immunohistochemistry was used to evaluate the lymphatic vasculature and donor-host connections after lung transplantation.

RESULTS

Immunohistochemistry of transplanted lungs demonstrated robust lymphatic vessels, and functional assays demonstrated lymphatic drainage in the transplanted lung that was comparable with that in native lungs. Lymphatic vessels in the donor lung exhibited active sprouting toward the host at the anastomosis within the first 3 days after lung transplantation, with more numerous and complex lymphatic sprouting developing thereafter. Donor lymphatic vessels were numerous at the site of anastomosis by day 14 after lung transplantation and formed physical connections with host lymphatic vessels, demonstrating a mechanism by which lymphatic drainage is reestablished in the transplanted lung.

CONCLUSIONS

Lymphatic drainage after lung transplantation is established by active sprouting of donor lymphatic vessels towards the host and the formation of donor-host lymphatic connections at the level of the transplant anastomosis.

FK506 induces lung lymphatic endothelial cell senescence and downregulates LYVE-1 expression, with associated decreased hyaluronan uptake

BACKGROUND

Therapeutic lymphangiogenesis in an orthotopic lung transplant model has been shown to improve acute allograft rejection that is mediated at least in part through hyaluronan drainage. Lymphatic vessel endothelial hyaluronan receptor (LYVE-1) expressed on the surface of lymphatic endothelial cells plays important roles in hyaluronan uptake. The impact of current immunosuppressive therapies on lung lymphatic endothelial cells is largely unknown. We tested the hypothesis that FK506, the most commonly used immunosuppressant after lung transplantation, induces lung lymphatic endothelial cell dysfunction.

METHODS

Lung lymphatic endothelial cells were cultured in vitro and treated with FK506. Telomerase activity was measured using the TRAP assay. Protein expression of LYVE-1 and senescence markers p21 and β-galactosidase was assessed with western blotting. Matrigel tubulation assay were used to investigate the effects of FK506 on TNF-α-induced lymphangiogenesis. Dual luciferase reporter assay was used to confirm NFAT-dependent transcriptional regulation of LYVE-1. Flow cytometry was used to examine the effects of FK506 on LYVE-1 in precision-cut-lung-slices ex vivo and on hyaluronan uptake in vitro.

RESULTS

In vitro, FK506 downregulated telomerase reverse transcriptase expression, resulting in decreased telomerase activity and subsequent induction of p21 expression and cell senescence. Treatment with FK506 decreased LYVE-1 mRNA and protein levels and resulted in decreased LEC HA uptake. Similar result showing reduction of LYVE-1 expression when treated with FK506 was observed ex vivo. We identified a putative NFAT binding site on the LYVE-1 promoter and cloned this region of the promoter in a luciferase-based reporter construct. We showed that this NFAT binding site regulates LYVE-1 transcription, and mutation of this binding site blunted FK506-dependent downregulation of LYVE-1 promoter-dependent transcription. Finally, FK506-treated lymphatic endothelial cells show a blunted response to TNF-α-mediated lymphangiogenesis.

CONCLUSION

FK506 alters lymphatic endothelial cell molecular characteristics and causes lymphatic endothelial cell dysfunction in vitro and ex vivo. These effects of FK506 on lymphatic endothelial cell may impair the ability of the transplanted lung to drain hyaluronan macromolecules in vivo. The implications of our findings on the long-term health of lung allografts merit more investigation.

Pseudomonas aeruginosa antibody response in cystic fibrosis decreases rapidly following lung transplantation

BACKGROUND

Specific Pseudomonas aeruginosa (PA) precipitating immunoglobulin G antibodies in serum are correlated with PA biofilm infection and are used as diagnostic and prognostic markers in cystic fibrosis (CF). The aim of this study was to examine the change of PA antibody response in CF patients after bilateral sequential lung transplantation (LTx).

METHODS

PA antibodies and airway bacteriology were retrospectively evaluated in 20 chronically infected CF patients, who underwent LTx between 2001 and 2016 at Rigshospitalet, Copenhagen. Yearly precipitin counts from one year before LTx and up to five years after LTx were compared. Monthly airway cultures were examined in the five-year period after LTx. In addition, crossed immunoelectrophoresis (CIE) were analysed for each patient for antigenic similarities from time of infection, pre-LTx and post-LTx.

RESULTS

All patients experienced a significant drop in PA antibodies from one year pre-LTx to one year post-LTx (p < 0.0001). The PA antibody level did not differ between those, who became reinfected immediately after LTx, and those, who did not. No patients regained the high pre-LTx precipitin levels in the following five years. The antigenic specificities of the sera post-LTx were in each patient similar to the antigenic specificities at the beginning of infection indicating a decades long memory of their immune response like an "immunological fingerprint".

CONCLUSIONS

After LTx a significant and continuous reduction in PA antibodies was observed. The reduction was independent of immediate reinfection after LTx. A novel three-factor explanatory model is presented.

Lymphatic vasculature in tumor metastasis and immunobiology

Lymphatic vessels are essential for tissue fluid homeostasis, immune cell trafficking, and intestinal lipid absorption. The lymphatics have long been recognized to serve as conduits for distant tumor dissemination. However, recent findings suggest that the regional lymphatic vasculature also shapes the immune microenvironment of the tumor mass and potentiates immunotherapy. This review discusses the role of lymphatic vessels in tumor metastasis and tumor immunity.

Hyaluronan and LYVE-1 and allograft function in lung transplantation recipients

Hyaluronan (HA) is associated with innate immune response activation and may be a marker of allograft dysfunction in lung transplant recipients. This was a prospective, single center study comparing levels of bronchioalveolar lavage (BAL) and serum HA and the HA immobilizer LYVE-1 in lung transplant recipients with and without acute cellular rejection (ACR). Chronic lung allograft dysfunction (CLAD)-free survival was also evaluated based on HA and LYVE-1 levels. 78 recipients were enrolled with a total of 115 diagnostic biopsies and 1.5 years of median follow-up. Serum HA was correlated with BAL HA (r = 0.25, p = 0.01) and with serum LYVE-1 (r = 0.32, p = 0.002). There was significant variation in HA and LYVE-1 over time, regardless of ACR status. Levels of serum HA (median 74.7 vs 82.7, p = 0.69), BAL HA (median 149.4 vs 134.5, p = 0.39), and LYVE-1 (mean 190.2 vs 183.8, p = 0.72) were not associated with ACR. CLAD-free survival was not different in recipients with any episode of elevated serum HA (HR = 1.5, 95% CI = 0.3–7.7, p = 0.61) or BAL HA (HR = 0.94, 95% CI = 0.2–3.6, p = 0.93). These results did not differ when stratified by bilateral transplant status. In this small cohort, serum HA, BAL HA, and LYVE-1 levels are not associated with ACR or CLAD-free survival in lung transplant recipients.

Glycogen synthase kinase 3-β inhibition induces lymphangiogenesis through β-catenin-dependent and mTOR-independent pathways

Lymphatic vessels play an important role in health and in disease. In this study, we evaluated the effects of GSK3-β inhibition on lung lymphatic endothelial cells in vitro. Pharmacological inhibition and silencing of GSK3-β resulted in increased lymphangiogenesis of lung lymphatic endothelial cells. To investigate mechanisms of GSK3-β-mediated lymphangiogenesis, we interrogated the mammalian/mechanistic target of rapamycin pathway and found that inhibition of GSK3-β resulted in PTEN activation and subsequent decreased activation of AKT, leading to decreased p-P70S6kinase levels, indicating inhibition of the mTOR pathway. In addition, consistent with a negative role of GSK3-β in β-catenin stability through protein phosphorylation, we found that GSK3-β inhibition resulted in an increase in β-catenin levels. Simultaneous silencing of β-catenin and inhibition of GSK3-β demonstrated that β-catenin is required for GSK3-β-induced lymphangiogenesis.

High altitude trekking after lung transplantation: a prospective study using lung ultrasound to detect comets tails for interstitial pulmonary edema in lung transplant recipients and healthy volunteers

The intensity of physical activity which can be tolerated after lung transplantation and the tolerance to prolonged exercise at high altitude are poorly investigated. Lung ultrasound comet tails have been used in the diagnosis of interstitial pulmonary edema and high pulmonary altitude edema. The aim was to assess the number of lung ultrasound comet tails and to monitor changes in the optic nerve sheath diameter (ONSD) during a climb to the top of Mount Kilimanjaro in 10 lung transplant recipients and 10 healthy controls at three different altitude levels: 1360, 3505, 4900 m. Lung transplant recipients showed a constant increase in comet tail scores with altitude, whereas control subjects only showed an increase at the highest measurement point. Differences between groups (transplant versus control) reached significance only after the first ascend: 0.9 (95% CI: -0.41; 2.21) vs. 0.1 (95% CI: -0.12; 0.32) (P = 0.2; 1360 m), 2.33 (95% CI: 0.64; 4.02) vs. 0.3 (95% CI: -0.18; 0.78) (P = 0.04; 3505 m), and 4.11 (95% CI: 0.13; 0.34) vs. 2.9 (95% CI: 0.49; 5.31) (P = 0.15; 4900 m); ONSD increased significantly in both groups from 3.53 (95% CI: 0.34; 0.66) at 1360 m to 4.11 (95% CI: 0.36; 0.71) at 4900 m (P < 0.05). Lungs of transplant recipients are able to adapt to altitude and capable of performing prolonged exercise at high altitude after slow ascend.

Secondary pulmonary alveolar proteinosis predominant in the transplanted lung in patients with idiopathic interstitial pneumonia: an autopsy case

A man in his 40 s with idiopathic interstitial pneumonia underwent cadaveric left single-lung transplantation from a brain-dead donor in October 2014. In October 2015, chest high-resolution computed tomography revealed centrilobular ground-glass opacities (GGOs) predominantly in the transplanted left lung, and subsequently, the shadows progressed to a geographic GGO without crazy paving. Bronchoalveolar lavage fluid analysis revealed an opaque and milky appearance, and cytopathology demonstrated foamy alveolar macrophages and abundant granular, acellular, eosinophilic, and amorphous material in the background. There was no evidence of infection. Serum anti-granulocyte-macrophage colony-stimulating factor antibody testing was negative. We diagnosed the patient with secondary pulmonary alveolar proteinosis (PAP) following lung transplantation. Autopsy revealed PAP findings predominant in the transplanted left lung, which also had dilated lymphatic vessels. In addition to defects in alveolar macrophage function from immunosuppressive therapy, impaired lymphatic drainage due to transplantation would contribute to the onset of secondary PAP in the transplanted lung.