No abstract

No abstract

Background The purpose of this study was to examine outcomes of a patient cohort undergoing intervention for carotid blowout syndrome (CBS) associated with head and neck cancer. Methods Patients with head and neck cancer who presented with carotid-distribution bleeding from 2000-2014 were identified in the medical record. Primary outcomes were short and mid-term mortality and recurrent bleeding. Standard statistical methods and survival analysis were used to analyze study population characteristics and outcomes. Results Thirty-seven patients were included in the study. The mean age was 60.1±11.4 (74% male). All malignancies were squamous cell type, stage IV, in a variety of primary locations: 32% oral cavity, 24% larynx, 16% superficial neck, with the remainder in the oro, naso, and hypopharynx. 51% of bleeds were of common carotid, 29% external carotid, and 19% internal carotid origin. 68% presented with acute hemorrhage, 24% with impending bleed, and 8% with threatened bleed. All patients underwent intervention: 38% received endovascular coil embolization, 30% stent grafts, 22% surgical ligation, and 10% primary vessel repair or bypass grafting. 10.8% of patients had perioperative stroke; other major complications were rare. Sixteen recurrent bleeding episodes involving 12 arteries occurred in 11 patients (29.73%). Median rebleeding time was seven days (IQR 6-49). Estimated recurrent bleeding risk at 30-days and 6 months was 24% and 34% respectively. 91.9% of patients survived to hospital discharge. 90-day and 1-year estimated survival was 60.9% and 36.6% respectively. Conclusions CBS associated with head and neck cancer carries poor mid- and long-term prognoses; however, mortality may be related more to the advanced stage of disease rather than carotid involvement or associated intervention. Both surgical and endovascular approaches may be efficacious in cases of acute hemorrhage but carry a significant risk of periprocedural stroke and recurrent bleeding.

Objectives The angiogenic drive in skeletal muscle ischemia remains poorly understood. Innate inflammatory pathways are activated during tissue injury and repair, suggesting that this highly conserved pathway may be involved in ischemia-induced angiogenesis. We hypothesize that one of the endogenous ligands for innate immune signaling, high mobility group box 1 (HMGB1), in combination with autophagic responses to hypoxia or nutrient deprivation plays an important role in angiogenesis. Methods Human dermal microvascular endothelial cells (EC) were cultured in normoxia or hypoxia (1% oxygen). Immunocytochemical analysis of HMGB1 subcellular localization, evaluation of tube formation, and Western blot analysis of myotubule light-chain 3 (LC3I) conversion to LC3II, as a marker of autophagy, were conducted. 3-methyladenine (3MA), chloroquine (CQ), or rapamycin were administered to inhibit or promote autophagy, respectively. In vivo, a murine hind-limb ischemia model was performed. Muscle samples were collected at 4 hours to evaluate for nuclear HMGB1 and at 14 days to examine endothelial density. Perfusion recovery in the hind-limbs was calculated by laser Doppler perfusion imaging (LDPI). Results Hypoxic EC exhibited reduced nuclear HMGB1 staining compared with normoxic cells (mean fluorescence intensity 186.9 ± 17.1 vs. 236.0 ± 1.6, respectively, P = 0.01) with a concomitant increase in cytosolic staining. HMGB1 treatment of ECs enhanced tube formation, an angiogenic phenotype of ECs. Neutralization of endogenous HMGB1 markedly impaired tube formation and inhibited LC3II formation. Inhibition of autophagy with 3MA or CQ abrogated tube formation while its induction with rapamycin enhanced tubing and promoted HMGB1 translocation. In vivo, ischemic skeletal muscle showed reduced the numbers of HMGB1 positive myocyte nuclei compared with nonischemic muscle (34.9% ± 1.9 vs. 51.7% ± 2.0, respectively, P<0.001). Injection of HMGB1 into ischemic hind-limbs increased perfusion recovery by 21% and increased EC density (49.2 ± 4.1vs. 34.2 ± 3.4 EC/HPF, respectively; p=0.02) at 14 days compared to control treated hind-limbs. Conclusion Nuclear release of HMGB1 and autophagy occur in ECs in response to hypoxia or serum depletion. HMGB1 and autophagy are necessary and likely play an interdependent role in promoting the angiogenic behavior of ECs. In vivo, HMGB1 promotes perfusion recovery and increased EC density after ischemic injury. These findings are the first to suggest a possible mechanistic link between autophagy and HMGB1 in EC angiogenic behavior and support the importance of innate immune pathways in angiogenesis.

Introduction We have previously shown that the danger signal High Mobility Group Box 1 (HMGB1) promotes angiogenesis when administered to ischemic muscle. HMGB1 signals through Toll-like receptor 4 (TLR4) as well as the receptor for advanced glycation end-products (RAGE). However, the actions of these receptors in ischemic injury and muscle recovery are not known. We hypothesize that TLR4 mediates tissue recovery and angiogenesis in response to ischemia. Methods Femoral artery ligation was performed in control, TLR4 competent (C3H/HeOuJ), and incompetent (C3H/HeJ) mice, as well as RAGE knockout mice and their C57B6 control counterparts. In other experiments, control mice were pretreated with anti-HMGBI neutralizing antibody before femoral artery ligation. After two weeks, limb perfusion was evaluated using laser Doppler perfusion imaging (LDPI) and reported as the ratio of blood flow in the ischemic to nonischemic limb. Muscle necrosis, fat replacement, and vascular density in the anterior tibialis muscle were quantified histologically. In vitro, TLR4 and RAGE expression was evaluated in human dermal microvascular endothelial cells (HDMVECs) in response to hypoxia. HDMVECs treated with HMGB1 alone and in the presence of anti-TLR4 antibody were probed for phosphorylated ERK (p-ERK), a signaling molecule critical to EC angiogenic behavior. Results Both anti-HMGB1 antibody as well as defective TLR4 signaling in HeJ mice resulted in prominent muscle necrosis two weeks after femoral artery ligation. Control HeOuJ mice had less necrosis than TLR4 incompetent HeJ mice, but a greater amount of fat replacement. In contrast to control C3H mice, control C57B6 mice demonstrated prominent muscle regeneration with very little necrosis. Muscle regeneration was not dependent on RAGE. While vascular density did not differ between strains, mice with intact RAGE and TLR4 signaling had less blood flow in ischemic limbs compared to mutant strains. In vitro, EC TLR4 expression increased in response to hypoxia while TLR4 antagonism decreased HMGB1-induced activation of ERK. Conclusion Both HMGB1 and TLR4 protect against muscle necrosis after hindlimb ischemia. However, muscle regeneration does not appear to be tied to vascular density. HMGB1 likely activates angiogenic behavior in EC in vitro, and this activation may be modulated by TLR4. The improvement in blood flow seen in mice with absent TLR4 and RAGE signaling may suggest anti-angiogenic roles for both receptors, or vasoconstriction induced by TLR4 and RAGE mediated inflammatory pathways.