Faculty Bibliography

BACKGROUND: Long considered to be inert organelles for lipid storage, lipid droplets (LDs) have recently attracted great interest as dynamic structures central to cellular lipid and energy metabolism. hypoxia-inducible gene (HIG2) and perilipin 2 (PLIN2, adipophilin) are LD-associated proteins known to be upregulated by hypoxia (Bensaad, 2014) and/or following von Hippel-Lindau (VHL) gene inactivation (Togashi, 2005; Yao, 2005). We sought to determine whether overexpression of HIG2 and PLIN2 in response to hypoxia or pseudohypoxia may be involved in these histopathologic features of glioma and hemangioblastoma. METHODS: Tumor specimens from 12 patients with glioma grade II-IV (age 3-59 y) and 23 patients with CNS hemangioblastoma (age 15-63 y) were analyzed by immunohistochemistry (IHC) to delineate their expression of HIG2 and PLIN2. To evaluate the role of hypoxia, glioblastoma (GBM) tissues (n = 2) were double-label immunostained for HIF-1alpha and PLIN2 (Zagzag, 2008). Additionally, cultures of tumor spheres isolated from GBM patients (n = 2) (Bayin, 2014) were exposed to hypoxic (1% O2) conditions for 24-72 h, and the cell proteins analyzed by Western blots. RESULTS: HIG2 and PLIN2 were consistently expressed on LDs in hypoxic glioma tumor cells, including pseudopalisading cells in GBMs, but not in adjacent hyperplastic vessels, inflammatory cells or normal brain tissue, independently of tumor grade or the presence of IDH1 (n = 3) and/or TP53 (n = 7) mutations. Likewise, LDs in stromal tumor cells in hemangioblastoma were intensely immunopositive for HIG2 and PLIN2. Double-label IHC showed tight co-expression of HIF-1a and PLIN2 in glioma tumor cells, consistent with the hypoxic regulation of PLIN2. Similarly, expression of HIF-1a and HIG2 proteins was upregulated in GBM tumor spheres under hypoxic conditions. CONCLUSIONS: Our results suggest that HIG2 and PLIN2 are involved in the hypoxic adaptation of lipid metabolism during tumorigenesis, and may serve as specific biomarkers of glioma tumor cells and stromal cells in CNS hemangioblastoma

At least 170 million people are chronically infected with hepatitis C virus (HCV). Owing to the narrow host range of HCV and restricted use of chimpanzees, there is currently no suitable animal model for HCV pathogenesis studies or the development of a HCV vaccine. To identify cellular determinants of interspecies transmission and establish a novel immunocompetent model system, we examined the ability of HCV to infect hepatocytes from a small nonhuman primate, the rhesus macaque (Macaca mulatta). We show that the rhesus orthologs of critical HCV entry factors support viral glycoprotein-dependent virion uptake. Primary hepatocytes from rhesus macaques are also permissive for HCV-RNA replication and particle production, which is enhanced when antiviral signaling is suppressed. We demonstrate that this may be owing to the diminished capacity of HCV to antagonize mitochondrial antiviral-signaling protein-dependent innate cellular defenses. To test the ability of HCV to establish persistent replication in vivo, we engrafted primary rhesus macaque hepatocytes into immunocompromised xenorecipients. Inoculation of resulting simian liver chimeric mice with either HCV genotype 1a or 2a resulted in HCV serum viremia for up to 10 weeks. CONCLUSION: Together, these data indicate that rhesus macaques may be a viable model for HCV and implicate host immunity as a potential species-specific barrier to HCV infection. We conclude that suppression of host immunity or further viral adaptation may allow robust HCV infection in rhesus macaques and creation of a new animal model for studies of HCV pathogenesis, lentivirus coinfection, and vaccine development. (Hepatology 2015;62:57-67).

The TLR7/8 agonist, Resiquimod has been used as an immune adjuvant in cancer vaccines. We evaluated the safety and immunogenicity of the cancer testis antigen NY-ESO-1 given in combination with Montanide with or without Resiquimod in high risk melanoma patients. In Part I of the study, patients received 100ug full length NY-ESO-1 protein emulsified in 1.25mL Montanide (day 1) followed by topical application of 1000mg of 0.2% Resiquimod gel on days 1 and 3 (Cohort 1) versus days 1, 3, and 5 (Cohort 2) of a 21 day cycle. In Part II, patients were randomized to receive 100ug NY-ESO-1 protein plus Montanide (day 1) followed by topical application of placebo gel (Arm-A; N=8) or 1000mg of 0.2% Resiquimod gel (Arm-B; N=12) using the dosing regimen established in Part I. The vaccine regimens were generally well-tolerated. NY-ESO-1 specific humoral responses were induced or boosted in all patients, many with high titers. In Part II, 16 of 20 patients in both arms had NY-ESO-1-specific CD4+ T cell responses. CD8+ T cell responses were only seen in 3 of 12 patients in Arm B. Patients with TLR7 SNP rs179008 had a greater likelihood of developing NY-ESO-1-specific CD8+ responses. In conclusion, NY-ESO-1 protein in combination with Montanide with or without topical Resiquimod is safe and induces both antibody and CD4+ cell responses in the majority of patients; the small proportion of CD8+ cell responses suggests that the addition of topical Resiquimod to Montanide is not sufficient to induce consistent NY-ESO-1 specific CD8+ cell responses.

In most exposed individuals, hepatitis C virus (HCV) establishes a chronic infection; this long-term infection in turn contributes to the development of liver diseases such as cirrhosis and hepatocellular carcinoma. The role of antibodies directed against HCV in disease progression is poorly understood. Neutralizing antibodies (nAbs) can prevent HCV infection in vitro and in animal models. However, the effects of nAbs on an established HCV infection are unclear. We demonstrate that three broadly nAbs-AR3A, AR3B, and AR4A-delivered with adeno-associated viral vectors can confer protection against viral challenge in humanized mice. Furthermore, we provide evidence that nAbs can abrogate an ongoing HCV infection in primary hepatocyte cultures and in a human liver chimeric mouse model. These results showcase a therapeutic approach to interfere with HCV infection by exploiting a previously unappreciated need for HCV to continuously infect new hepatocytes to sustain a chronic infection.

Adenosine has an important role in inflammation and tissue remodeling and promotes dermal fibrosis by adenosine receptor (A2AR) activation. Adenosine may be formed intracellularly from adenine nucleotides or extracellularly through sequential phosphohydrolysis of released ATP by nucleoside triphosphate diphosphohydrolase (CD39) and ecto-5'-nucleotidase (CD73). Because the role of these ecto-enzymes in fibrosis appears to be tissue specific, we determined whether these ectonucleotidases were directly involved in diffuse dermal fibrosis. Wild-type and mice globally deficient in CD39 knockout (CD39KO), CD73 (CD73KO), or both (CD39/CD73DKO) were challenged with bleomycin. Extracellular adenosine levels and dermal fibrosis were quantitated. Adenosine release from skin cultured ex vivo was increased in wild-type mice after bleomycin treatment but remained low in skin from CD39KO, CD73KO, or CD39/CD73DKO bleomycin-treated mice. Deletion of CD39 and/or CD73 decreased the collagen content, and prevented skin thickening and tensile strength increase after bleomycin challenge. Decreased dermal fibrotic features were associated with reduced expression of the profibrotic mediators, transforming growth factor-beta1 and connective tissue growth factor, and diminished myofibroblast population in CD39- and/or CD73-deficient mice. Our work supports the hypothesis that extracellular adenosine, generated in tandem by ecto-enzymes CD39 and CD73, promotes dermal fibrogenesis. We suggest that biochemical or biological inhibitors of CD39 and/or CD73 may hold promise in the treatment of dermal fibrosis in diseases such as scleroderma.

BACKGROUND: Young breast cancer (BC) patients less than 45 years old are at higher risk of dying from the disease when compared to their older counterparts. However, specific risk factors leading to this poorer outcome have not been identified. METHODS: One candidate is iron deficiency, as this is common in young women and a clinical feature of young age. In the present study, we used immuno-competent and immuno-deficient mouse xenograft models as well as hemoglobin as a marker of iron status in young BC patients to demonstrate whether host iron deficiency plays a pro-metastatic role. RESULTS: We showed that mice fed an iron-deficient diet had significantly higher tumor volumes and lung metastasis compared to those fed normal iron diets. Iron deficiency mainly altered Notch but not TGF-beta and Wnt signaling in the primary tumor, leading to the activation of epithelial mesenchymal transition (EMT). This was revealed by increased expression of Snai1 and decreased expression of E-cadherin. Importantly, correcting iron deficiency by iron therapy reduced primary tumor volume, lung metastasis, and reversed EMT markers in mice. Furthermore, we found that mild iron deficiency was significantly associated with lymph node invasion in young BC patients (p<0.002). CONCLUSIONS: Together, our finding indicates that host iron deficiency could be a contributor of poor prognosis in young BC patients.