Faculty Bibliography

OBJECTIVES/HYPOTHESIS/OBJECTIVE:Head and neck squamous cell carcinoma (HNSCC) cells are resistant to cell death induced by tumor necrosis factor ligands such as tumor necrosis factor α (TNFα) or TNF-related apoptosis-inducing ligand (TRAIL) and cytotoxic chemotherapies. Recently, genetic alterations in cell death pathways, including inhibitor of apoptosis proteins, have been demonstrated in HNSCC. We investigated the effects of birinapant, a novel, second mitochondria-derived activator of caspases (SMAC)-mimetic that targets inhibitor of apoptosis proteins, alone and in combination with TNFα, TRAIL, or chemotherapy docetaxel. STUDY DESIGN/METHODS:Experimental study using human HNSCC cell lines in vitro and xenograft mouse model in vivo. METHODS:A panel of HNSCC cell lines with varying genetic alterations in cell death pathway components were treated with birinapant ± TNFα, TRAIL, and docetaxel and were assessed for effects on cell density, cell cycle, and death. Synergism was determined at varying concentrations of treatments using the Chou-Talalay method. Combination studies using birinapant ± docetaxel were performed in a xenograft mouse model. RESULTS:Birinapant, alone or in combination with TNFα or TRAIL, decreased cell density in cell lines, with IC50 s ranging from 0.5 nM to > 1 µM. Birinapant alone or with TNF significantly increased subG0 cell death in different lines. Docetaxel showed synergism with birinapant ± TNFα in vitro. Birinapant monotherapy-inhibited growth in a tumor xenograft model resistant to docetaxel, and combination treatment further delayed growth. CONCLUSIONS:Birinapant alone or in combination with TNFα or TRAIL and docetaxel decreased cell density, increased cell death, and displayed antitumor activity in a preclinical HNSCC xenograft exhibiting aberrations in cell death pathway components and docetaxel resistance.

OBJECT/OBJECTIVE:Endoscopic endonasal treatment of petrous apex cholesterol granulomas allows for a natural drainage pathway into the nasopharynx. Because of the limited number of case series in the literature, there is limited evidence of recurrence rates and outcomes following endoscopic endonasal management. The purpose of this study was to determine the surgical outcomes of endoscopic endonasal approaches in the treatment of cholesterol granulomas of the petrous apex. METHODS:A systematic literature review was performed using PubMed for articles published from January 1980 to April 2014 to identify all studies reporting outcomes for endoscopic endonasal surgical management of cholesterol granulomas of the petrous apex. Operative approach, use of a stent, symptom outcome, restenosis, cyst recurrence, reoperation, and complications were extracted from included studies. RESULTS:A total of 53 patient cases were included from 22 relevant studies. The mean age was 41 years, and 26 patients (49%) were female. Stents were used in 45.1% of cases. Symptom resolution or improvement was seen in 98.6% of cases at follow-up (mean follow-up 20 months). Complications were reported in 13.2% of cases, with the most common complication being epistaxis. Restenosis on follow-up office endoscopic examination occurred in 9 of 45 cases (20.0%). Only 4 of these restenosis cases resulted in symptomatic cyst recurrence, resulting in an overall recurrence rate of 7.5%. The mean time from surgery to cyst recurrence was 13.5 months. The rate of symptomatic cyst recurrence was 10.7% in cases without the use of a stent compared with 4.3% in cases with stent placement (p = 0.6). CONCLUSIONS:Based on current literature, endoscopic endonasal approaches result in a high rate of symptom improvement or resolution. Complication rates are lower than prior case series that have utilized open approaches. Asymptomatic restenosis can be managed conservatively, since it is associated with symptomatic cyst recurrence less than half of the time. This study revealed a nonsignificant trend toward a decrease in symptomatic cyst recurrence when a stent was used, but further work is needed to clarify its impact.

BACKGROUND:Current immunosuppressive therapy after heart transplantation either generally suppresses the recipient's entire immune system or is mainly targeting T-lymphocytes. Monocytes/macrophages are recognized as a hallmark of acute allograft rejection, but the roles that they play are not well characterized in vivo, because the tools for accessing in situ macrophage infiltration are lacking. In this study, we used MRI to investigate the role of macrophages in acute heart allograft rejection by cellular and functional MRI with selectively depleted systemic macrophages without affecting other leukocyte population, as well as to explore the possibility that macrophages could be an alternative therapeutic target. METHODS AND RESULTS/RESULTS:A rodent heterotopic working heart-lung transplantation model was used for studying acute allograft rejection. Systemic macrophages were selectively depleted by treating recipient animals with clodronate-liposomes. Macrophage infiltration in the graft hearts was monitored by cellular MRI with in vivo ultrasmall superparamagnetic iron oxide particles labeling. Graft heart function was evaluated by tagging MRI followed by strain analysis. Clodronate-liposome treatment depletes circulating monocytes/macrophages in transplant recipients, and both cellular MRI and pathological examinations indicate a significant reduction in macrophage accumulation in the rejecting allograft hearts. In clodronate-liposome-treated group, allograft hearts exhibited preserved tissue integrity, partially reversed functional deterioration, and prolonged graft survival, compared with untreated controls. CONCLUSIONS:Cardiac cellular and functional MRI is a powerful tool to explore the roles of targeted immune cells in vivo. Our results indicate that macrophages are essential in acute cardiac allograft rejection, and selective depletion of macrophages with clodronate-liposomes protects hearts against allograft rejection, suggesting a potential therapeutic avenue. Our findings show that there is a finite risk of forming an intraventricular mass, presumably from the cellular debris or lipid material. Further optimization of the dosing protocol is necessary before clinical applications.

Current diagnosis of organ rejection following transplantation relies on tissue biopsy, which is not ideal due to sampling limitations and risks associated with the invasive procedure.We have previously shown that cellular magnetic resonance imaging (MRI) of iron-oxide labeled immune-cell infiltration can provide a noninvasive measure of rejection status by detecting areas of hypointensity on T 2*-weighted images. In this study, we tested the feasibility of using a fluorine-based cellular tracer agent to detect macrophage accumulation in rodent models of acute allograft rejection by fluorine-19 ((19) F) MRI and magnetic resonance spectroscopy. This study used two rat models of acute rejection, including abdominal heterotopic cardiac transplant and orthotopic kidney transplant models. Following in vivo labeling of monocytes and macrophages with a commercially available agent containing perfluoro-15-crown-5-ether, we observed (19) F-signal intensity in the organs experiencing rejection by (19) F MRI, and conventional (1) H MRI was used for anatomical context. Immunofluorescence and histology confirmed macrophage labeling. These results are consistent with our previous studies and show the complementary nature of the two cellular imaging techniques. With no background signal, (19) F MRI/magnetic resonance spectroscopy can provide unambiguous detection of fluorine labeled cells, and may be a useful technique for detecting and quantifying rejection grade in patients.

BACKGROUND:Long-term survival of heart transplants is hampered by chronic rejection (CR). Studies indicate the involvement of host macrophages in the development of CR; however, the precise role of these cells in CR is unclear. Thus, it is important to develop noninvasive techniques to serially monitor the movement and distribution of recipient macrophages in chronic cardiac allograft rejection in vivo. METHODS AND RESULTS/RESULTS:We have employed a rat heterotopic working-heart CR model for a magnetic resonance imaging experiment. Twenty-one allograft (PVG.1U-->PVG.R8) and 9 isograft (PVG.R8-->PVG.R8) transplantations were performed. Recipient macrophages are labeled via intravenous injection of micron-sized paramagnetic iron oxide particles (0.9 microm in diameter) at a dose of 4.5 mg Fe per rat 1 day before transplantation. Serial in vivo magnetic resonance images were acquired for up to 16 weeks. The migration of labeled recipient cells in our CR model, in which cardiac CR is evident at 3 weeks and most extensive by 16 weeks after transplantation, can be assessed with the use of in vivo magnetic resonance imaging for >100 days after a single micron-sized paramagnetic iron oxide injection. The location and distribution of labeled recipient cells were confirmed with magnetic resonance microscopy and histology. CONCLUSIONS:This approach may improve our understanding of the immune cells involved in CR and the management of heart transplantation. Moreover, this study demonstrates the feasibility of noninvasively observing individual targeted cells over long time periods by serial in vivo magnetic resonance imaging.