Granzyme B Contributes to Barrier Dysfunction in Oxazolone-Induced Skin Inflammation through E-Cadherin and FLG Cleavage

Atopic dermatitis (AD) is the most common inflammatory skin condition. Skin barrier dysfunction is of major importance in AD because it facilitates allergen sensitization and systemic allergic responses. Long regarded as a pro-apoptotic protease, emerging studies indicate granzyme B (GzmB) to have extracellular roles involving the proteolytic cleavage of extracellular matrix, cell adhesion proteins, and basement membrane proteins. Minimally expressed in normal skin, GzmB is elevated in AD and is positively correlated with disease severity and pruritus. We hypothesized that GzmB contributes to AD through extracellular protein cleavage. A causative role for GzmB was assessed in an oxazolone-induced murine model of dermatitis, comparing GzmB^-/- mice with wild-type mice, showing significant reductions in inflammation, epidermal thickness, and lesion formation in GzmB^-/- mice. Topical administration of a small-molecule GzmB inhibitor reduced disease severity compared with vehicle-treated controls. Mechanistically, GzmB impaired epithelial barrier function through E-cadherin and FLG cleavage. GzmB proteolytic activity contributes to impaired epidermal barrier function and represents a valid therapeutic target for AD.

Soluble Wood Smoke Extract Promotes Barrier Dysfunction in Alveolar Epithelial Cells through a MAPK Signaling Pathway

Wildfire smoke induces acute pulmonary distress and is of particular concern to risk groups such as the sick and elderly. Wood smoke (WS) contains many of the same toxic compounds as those found in cigarette smoke (CS) including polycyclic aromatic hydrocarbons, carbon monoxide, and free radicals. CS is a well-established risk factor for respiratory diseases such as asthma and COPD. Limited studies investigating the biological effects of WS on the airway epithelium have been performed. Using a cell culture-based model, we assessed the effects of a WS-infused solution on alveolar epithelial barrier function, cell migration, and survival. The average geometric mean of particles in the WS was 178 nm. GC/MS analysis of the WS solution identified phenolic and cellulosic compounds. WS exposure resulted in a significant reduction in barrier function, which peaked after 24 hours of continuous exposure. The junctional protein E-cadherin showed a prominent reduction in response to increasing concentrations of WS. Furthermore, WS significantly repressed cell migration following injury to the cell monolayer. There was no difference in cell viability following WS exposure. Mechanistically, WS exposure induced activation of the p44/42, but not p38, MAPK signaling pathway, and inhibition of p44/42 phosphorylation prevented the disruption of barrier function and loss of E-cadherin staining. Thus, WS may contribute to the breakdown of alveolar structure and function through a p44/42 MAPK-dependent pathway and may lead to the development and/or exacerbation of respiratory pathologies with chronic exposure.

The retinoblastoma protein regulates hypoxia-inducible genetic programs, tumor cell invasiveness and neuroendocrine differentiation in prostate cancer cells

Loss of tumor suppressor proteins, such as the retinoblastoma protein (Rb), results in tumor progression and metastasis. Metastasis is facilitated by low oxygen availability within the tumor that is detected by hypoxia inducible factors (HIFs). The HIF1 complex, HIF1α and dimerization partner the aryl hydrocarbon receptor nuclear translocator (ARNT), is the master regulator of the hypoxic response. Previously, we demonstrated that Rb represses the transcriptional response to hypoxia by virtue of its association with HIF1. In this report, we further characterized the role Rb plays in mediating hypoxia-regulated genetic programs by stably ablating Rb expression with retrovirally-introduced short hairpin RNA in LNCaP and 22Rv1 human prostate cancer cells. DNA microarray analysis revealed that loss of Rb in conjunction with hypoxia leads to aberrant expression of hypoxia-regulated genetic programs that increase cell invasion and promote neuroendocrine differentiation. For the first time, we have established a direct link between hypoxic tumor environments, Rb inactivation and progression to late stage metastatic neuroendocrine prostate cancer. Understanding the molecular pathways responsible for progression of benign prostate tumors to metastasized and lethal forms will aid in the development of more effective prostate cancer therapies.

Recombinant Decorin Fusion Protein Attenuates Murine Abdominal Aortic Aneurysm Formation and Rupture

Decorin (DCN) is a small-leucine rich proteoglycan that mediates collagen fibrillogenesis, organization, and tensile strength. Adventitial DCN is reduced in abdominal aortic aneurysm (AAA) resulting in vessel wall instability thereby predisposing the vessel to rupture. Recombinant DCN fusion protein CAR-DCN was engineered with an extended C-terminus comprised of CAR homing peptide that recognizes inflamed blood vessels and penetrates deep into the vessel wall. In the present study, the role of systemically-administered CAR-DCN in AAA progression and rupture was assessed in a murine model. Apolipoprotein E knockout (ApoE-KO) mice were infused with angiotensin II (AngII) for 28 days to induce AAA formation. CAR-DCN or vehicle was administrated systemically until day 15. Mortality due to AAA rupture was significantly reduced in CAR-DCN-treated mice compared to controls. Although the prevalence of AAA was similar between vehicle and CAR-DCN groups, the severity of AAA in the CAR-DCN group was significantly reduced. Histological analysis revealed that CAR-DCN treatment significantly increased DCN and collagen levels within the aortic wall as compared to vehicle controls. Taken together, these results suggest that CAR-DCN treatment attenuates the formation and rupture of Ang II-induced AAA in mice by reinforcing the aortic wall.

Abstract 487: Systemic Administration of Target-Seeking, Vessel Penetrating Recombinant Decorin Fusion Protein, Car-DCN, Reduces Severity of Abdominal Aortic Aneurysm in Mice

Objective: Decorin (DCN) is a small leucine-rich proteoglycan that mediates collagen fibrollogenesis, organization, and tensile strength. DCN is reduced in abdominal aortic aneurysm (AAA) through a Granzyme B-dependent mechanism resulting in vessel wall instability and aneurysm formation. A recombinant decorin fusion protein CAR-DCN was engineered with an extended C-terminus comprised of CAR homing peptide that recognizes inflammatory blood vessels and penetrates deep into the vessel wall. In the present study, we sought to evaluate the role of systemically administered CAR-DCN in AAA progression and rupture rate in a murine model.

Approach and Results: To induce aneurysm, apolipoprotein E knockout (ApoE-KO) mice were infused with 28 days of angiotensin II (AngII). CAR-DCN or vehicle was systemically administrated until day 15. We observed a significant increase in the survival of CAR-DCN-treated mice (93%) compared to vehicle controls (60%). Although the incidence of AAA onset was similar between vehicle and CAR-DCN groups, the severity of aneurysm in the CAR-DCN group was significantly reduced. Furthermore, histological analysis revealed that CAR-DCN treatment significantly increased DCN and collagen levels in aortic walls compares to vehicle controls.

Conclusions: CAR-DCN administration attenuated the severity of Ang II-induced AAA in mice by reinforcing the vessel wall. CAR-DCN may represent a novel therapeutic strategy to attenuate AAA progression and rupture.

Abstract 2922: Loss of retinoblastoma protein dysregulates HIF1-mediated genetic programs, and promotes tumor cell invasiveness and neuroendocrine differentiation in prostate cancer cells

Loss of tumour suppressor proteins, such as the retinoblastoma protein (Rb), results in tumour progression and metastasis. Metastasis is facilitated by low oxygen availability within the tumour that is detected by hypoxia inducible factors (HIFs). The HIF1 complex, HIF1α and its dimerization partner the aryl hydrocarbon receptor nuclear translocator (ARNT), is the master regulator of the hypoxic response. Previously, we demonstrated that Rb represses the transcriptional response to hypoxia by virtue of its association with HIF1. In this report, we further characterized the role of Rb in HIF1-regulated genetic programs by stably ablating Rb expression with retrovirally-introduced short hairpin RNA in LNCaP and 22rV1 human prostate cancer cells. DNA microarray analysis revealed that Rb regulates specific chromosomal gene clusters and loss of Rb in conjunction with hypoxia leads to dysregulation of HIF1-regulated genetic programs that promote cell invasion and neuroendocrine differentiation. Gene ontology analysis of the hypoxia-inducible genes sensitive to loss of Rb revealed that a significant portion of these genes are involved in neuroendocrine differentiation (NED), specifically ENO2, KISS1R and HTR5A. ENO2 is the bonafide marker of neuroendocrine differentiation and it's presence is a signature of late stage castrate resistant prostate cancer. Furthermore, we have functional evidence KISS1R is linked to intracellular calcium mobilization in 22RV1 cells. We have demonstrated that increased expression of HIF-regulated genes in response to loss of Rb activates Akt and ERK signaling pathways and promotes neuroendocrine differentiation and invasion. Inhibition of these signaling pathways significantly decreased actin polymerization in LNCaP cells. For the first time, we have established a direct link between hypoxic tumour environments, Rb inactivation and progression to late stage metastatic neuroendocrine prostate cancer. Understanding the molecular pathways responsible for progression of benign prostate tumours to metastasized and lethal forms will aid in the development of more effective prostate cancer therapies.

Citation Format: Mark Labrecque, Mandeep Takhar, Rebecca J. Nason, Stephanie Santacruz, Kevin Tam, Shabnam Massah, Anne Haegert, Robert Bell, Manuel Altamirano-Dimas, Colin Collins, Frank Lee, Gratien Prefontaine, Michael Cox, Timothy Beischlag. Loss of retinoblastoma protein dysregulates HIF1-mediated genetic programs, and promotes tumor cell invasiveness and neuroendocrine differentiation in prostate cancer cells. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2922.

Induction of Cytotoxicity in Pyridine Analogues of the Anti-metastatic Ru(III) Complex NAMI-A by Ferrocene Functionalization

A series of novel ferrocene (Fc) functionalized Ru(III) complexes was synthesized and characterized. These compounds are derivatives of the anti-metastatic Ru(III) complex imidazolium [trans-RuCl4(1H-imidazole) (DMSO-S)] (NAMI-A) and are derived from its pyridine analogue (NAMI-Pyr), with direct coupling of Fc to pyridine at the 4 or 3 positions, or at the 4 position via a two-carbon linker, which is either unsaturated (vinyl) or saturated (ethyl). Electron paramagnetic resonance (EPR) and UV-vis spectroscopic studies of the ligand exchange processes of the compounds in phosphate buffered saline (PBS) report similar solution behavior to NAMI-Pyr. However, the complex with Fc substitution at the 3 position of the coordinated pyridine shows greater solution stability, through resistance to the formation of oligomeric species. Further EPR studies of the complexes with human serum albumin (hsA) indicate that the Fc groups enhance noncoordinate interactions with the protein and help to inhibit the formation of protein-coordinated species, suggesting the potential for enhanced bioavailability. Cyclic voltammetry measurements demonstrate that the Fc groups modestly reduce the reduction potential of the Ru(III) center as compared to NAMI-Pyr, while the reduction potentials of the Fc moieties of the four compounds vary by 217 mV, with the longer linkers giving significantly lower values of E1/2. EPR spectra of the compounds with 2-carbon linkers show the formation of a high-spin Fe(III) species (S = 5/2) in PBS with a distinctive signal at g = 4.3, demonstrating oxidation of the Fe(II) ferrocene center and likely reflecting degradation products. Density functional theory calculations and paramagnetic (1)H NMR describe delocalization of spin density onto the ligands and indicate that the vinyl linker could be a potential pathway for electron transfer between the Ru and Fe centers. In the case of the ethyl linker, electron transfer is suggested to occur via an indirect mechanism enabled by the greater flexibility of the ligand. In vitro assays with the SW480 cell line reveal cytotoxicity induced by the ruthenium ferrocenylpyridine complexes that is at least an order of magnitude higher than the unfunctionalized complex, NAMI-Pyr. Furthermore, migration studies with LNCaP cells reveal that Fc functionalization does not reduce the ability of the compounds to inhibit cell motility. Overall, these studies demonstrate that NAMI-A-type compounds can be functionalized with redox-active ligands to produce both cytotoxic and anti-metastatic activity.

[Cochleovestibular hypofunction syndrome of infrequent origin. Thrombosis of venous endotracheal sinuses]

First appearance of the lateral sinus and jugular gulf thrombosis use to be a neurologic syndrome including headache, vomiting, convulsions, hydrocephalus, etc. We present a case in which the first and only symptom was the classic triad of Médière's disease: vertigo, tinnitus and hearing loss. We also discuss the radiological study, treatment and the literature review.