Lymph Node Transplantation Decreases Swelling and Restores Immune Responses in a Transgenic Model of Lymphedema

Introduction Secondary lymphedema is a common complication of cancer treatment and recent studies have demonstrated that lymph node transplantation (LNT) can decrease swelling, as well as the incidence of infections. However, although these results are exciting, the mechanisms by which LNT improves these pathologic findings of lymphedema remain unknown. Using a transgenic mouse model of lymphedema, this study sought to analyze the effect of LNT on lymphatic regeneration and T cell-mediated immune responses. Methods We used a mouse model in which the expression of the human diphtheria toxin receptor is driven by the FLT4 promoter to enable the local ablation of the lymphatic system through subdermal hindlimb diphtheria toxin injections. Popliteal lymph node dissection was subsequently performed after a two-week recovery period, followed by either orthotopic LNT or sham surgery after an additional two weeks. Hindlimb swelling, lymphatic vessel regeneration, immune cell trafficking, and T cell-mediated immune responses were analyzed 10 weeks later. Results LNT resulted in a marked decrease in hindlimb swelling, fibroadipose tissue deposition, and decreased accumulation of perilymphatic inflammatory cells, as compared to controls. In addition, LNT induced a marked lymphangiogenic response in both capillary and collecting lymphatic vessels. Interestingly, the resultant regenerated lymphatics were abnormal in appearance on lymphangiography, but LNT also led to a notable increase in dendritic cell trafficking from the periphery to the inguinal lymph nodes and improved adaptive immune responses. Conclusions LNT decreases pathological changes of lymphedema and was shown to potently induce lymphangiogenesis. Lymphatic vessels induced by LNT were abnormal in appearance, but were functional and able to transport antigen-presenting cells. Animals treated with LNT have an increased ability to mount T cell-mediated immune responses when sensitized to antigens in the affected hindlimb

Data from: Th2 cytokines inhibit lymphangiogenesis

Lymphangiogenesis is the process by which new lymphatic vessels grow in response to pathologic stimuli such as wound healing, inflammation, and tumor metastasis. It is well-recognized that growth factors and cytokines regulate lymphangiogenesis by promoting or inhibiting lymphatic endothelial cell (LEC) proliferation, migration and differentiation. Our group has shown that the expression of T-helper 2 (Th2) cytokines is markedly increased in lymphedema, and that these cytokines inhibit lymphatic function by increasing fibrosis and promoting changes in the extracellular matrix. However, while the evidence supporting a role for T cells and Th2 cytokines as negative regulators of lymphatic function is clear, the direct effects of Th2 cytokines on isolated LECs remains poorly understood. Using in vitro and in vivo studies, we show that physiologic doses of interleukin-4 (IL-4) and interleukin-13 (IL-13) have profound anti-lymphangiogenic effects and potently impair LEC survival, proliferation, migration, and tubule formation. Inhibition of these cytokines with targeted monoclonal antibodies in the cornea suture model specifically increases inflammatory lymphangiogenesis without concomitant changes in angiogenesis. These findings suggest that manipulation of anti-lymphangiogenic pathways may represent a novel and potent means of improving lymphangiogenesis

The Impact of the Cosurgeon Model on Bilateral Autologous Breast Reconstruction.

BACKGROUND: Microsurgical breast reconstructions (MBRs) are time and labor intensive procedures. To circumvent these barriers, plastic surgeons have started working together as cosurgeons (CSs). This study aims to evaluate the impact of the CS model (CSM) specifically on bilateral MBR. The hypothesis is that CS procedures reduce operative time and surgical complications. STUDY DESIGN: This was a single institutional retrospective cohort study, which included all consecutive patients who underwent bilateral MBR from 2014 to 2016. Patients were grouped into single surgeon (SS) or CSs based on the number of the attending plastic surgeons present. Demographic and clinical characteristics including age, body mass index, smoking, American Society of Anesthesiologist class, radiation, and the timing of the reconstruction were assessed. Univariate and multivariate analyses were performed for outcomes including operative time and postoperative complications. RESULTS: Of the 136 patients included in the study, 41% had breast reconstruction performed by CSs, whereas 59% had a SS. Sociodemographic features were evenly distributed with the exception of a greater number of delayed reconstructions in the SS group (33 vs. 13%; p <0.01). Pedicle TRAMS (transverse rectus abdominis musculocutaneous flaps) were performed in 5 versus 0% of SS versus CS cases, respectively. Rates of major (4 vs. 16%) and minor (11 vs. 24%) complications were significantly lower in CS procedures. Multivariate analyses demonstrated CS operations required significantly shorter operative time by 73 minutes (p <0.001), and trended toward a reduced postoperative complication rate (p= 0.07). CONCLUSION: The CSM is associated with improved operative efficiency for bilateral MBR. Further evaluation of the CSM may prove useful in other surgical disciplines with time and labor intense procedures

Th2 cytokines inhibit lymphangiogenesis.

Lymphangiogenesis is the process by which new lymphatic vessels grow in response to pathologic stimuli such as wound healing, inflammation, and tumor metastasis. It is well-recognized that growth factors and cytokines regulate lymphangiogenesis by promoting or inhibiting lymphatic endothelial cell (LEC) proliferation, migration and differentiation. Our group has shown that the expression of T-helper 2 (Th2) cytokines is markedly increased in lymphedema, and that these cytokines inhibit lymphatic function by increasing fibrosis and promoting changes in the extracellular matrix. However, while the evidence supporting a role for T cells and Th2 cytokines as negative regulators of lymphatic function is clear, the direct effects of Th2 cytokines on isolated LECs remains poorly understood. Using in vitro and in vivo studies, we show that physiologic doses of interleukin-4 (IL-4) and interleukin-13 (IL-13) have profound anti-lymphangiogenic effects and potently impair LEC survival, proliferation, migration, and tubule formation. Inhibition of these cytokines with targeted monoclonal antibodies in the cornea suture model specifically increases inflammatory lymphangiogenesis without concomitant changes in angiogenesis. These findings suggest that manipulation of anti-lymphangiogenic pathways may represent a novel and potent means of improving lymphangiogenesis

Inhibition of Inflammation and iNOS Improves Lymphatic Function in Obesity

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IL-4 or IL-13 blockade increases inflammatory lymphangiogenesis.

<p><b>A.</b> Representative gross images of corneas 14 days after suture placement. <b>B.</b> Representative immunofluorescent cornea whole mount images for LYVE-1. Scale bar = 100μm. <b>C.</b> Quantification of lymphatic vessel area per 0.25mm². Control vs. IL-4mAb (n = 8 in each; *p<0.001); control vs. IL-13mAb (n = 8 in each; *p<0.001); IL-4mAb vs. IL-13mAb (n = 8 in each; p = NS). <b>D.</b> Quantification of lymphatic vessel volume per 0.25mm². Control vs. IL-4mAb (n = 8 in each; *p<0.001); control vs. IL-13mAb (n = 8 in each; *p<0.001); IL-4mAb vs. IL-13mAb (n = 8 in each; *p<0.05).</p

rhIL-4 and rhIL-13 inhibit hLEC tubule formation.

<p><b>A.</b> Representative images of cultured hLECs tubule formation on matrigel after treatment with 50 ng/ml rhIL-4 or rhIL-13 protein, or media alone (control) for 12 hours. <b>B.</b> Quantification of tubule formation per high-power field. Control vs. rhIL-4 (n = 5–8 in each; *p<0.01); control vs. rhIL-13 (n = 5–8 in each; *p<0.01); rhIL-4 vs. rhIL-13 (n = 5–8 in each; p = NS).</p