Water molecules mute the dependence of the double-layer potential profile on ionic strength

We present the results of molecular dynamics simulations of a nanoscale electrochemical cell. The simulations include an aqueous electrolyte solution with varying ionic strength (i.e., concentrations ranging from 0-4 M) between a pair of metallic electrodes held at constant potential difference. We analyze these simulations by computing the electrostatic potential profile of the electric double-layer region and find it to be nearly independent of ionic concentration, in stark contrast to the predictions of standard continuum-based theories. We attribute this lack of concentration dependence to the molecular influences of water molecules at the electrode-solution interface. These influences include the molecular manifestation of water's dielectric response, which tends to drown out the comparatively weak screening requirement of the ions. To support our analysis, we decompose water's interfacial response into three primary contributions: molecular layering, intrinsic (zero-field) orientational polarization, and the dipolar dielectric response.

Targeted TNF-α Overexpression Drives Salivary Gland Inflammation

Chronic inflammation of the salivary glands from pathologic conditions such as Sjögren's syndrome can result in glandular destruction and hyposalivation. To understand which molecular factors may play a role in clinical cases of salivary gland hypofunction, we developed an aquaporin 5 (AQP5) Cre mouse line to produce genetic recombination predominantly within the acinar cells of the glands. We then bred these mice with the TNF-αglo transgenic line to develop a mouse model with salivary gland-specific overexpression of TNF-α; which replicates conditions seen in sialadenitis, an inflammation of the salivary glands resulting from infection or autoimmune disorders such as Sjögren's syndrome. The resulting AQP5-Cre/TNF-αglo mice display severe inflammation in the salivary glands with acinar cell atrophy, fibrosis, and dilation of the ducts. AQP5 expression was reduced in the salivary glands, while tight junction integrity appeared to be disrupted. The immune dysregulation in the salivary gland of these mice led to hyposalivation and masticatory dysfunction.

Abstract P4-04-12: Enhancing the immunogenicity of breast cancer cells to stimulate innate immunity and augment the effects of cellular immunotherapy

A promising strategy for treating metastatic breast cancer is engaging the immune system to destroy disseminated breast cancer cells. However, breast cancer is a challenge for immunotherapy because of its inherent genetic heterogeneity and decreased immunogenicity. There is an unmet need to develop new, targeted therapies for breast cancer that stimulate the immune system and can be used in combination with checkpoint blockade or adoptive cell transfer to fight metastatic disease. One potential approach is to generate dying breast cancer cells that operate like a vaccine to stimulate a tumor-specific immune response. This is termed immunogenic cell death (ICD) and is characterized by a unique molecular signature, involving the release of molecules that attract and stimulate phagocytes like dendritic cells (DCs) and that could sensitize tumor cells to killing by natural killer (NK) cells. With the discovery of new ICD-inducing agents, interest in this approach is increasing. However, the current doses of drugs used to induce ICD may be too high to translate into clinically relevant regimens. To address these problems, our group developed a novel cytotoxic peptide, CT20p, and a nanotechnology-based platform to deliver and concentrate CT20p in breast tumors. We found that treatment of a murine xenograft model with nanomolar amounts of CT20p, encapsulated in nanoparticles formed with a novel hyperbranched polyester polymer (HBPE-NPs), resulted in regression of breast cancer tumors, and that dying breast cancer cells expressed markers characteristic of ICD, such as the pre-mortem exposure of the "eat me" signal, calreticulin (Crt). The intracellular target of CT20p is a protein called chaperonin-containing T-complex (CCT), which is essential for the folding of actin and tubulin and other critical proteins into their native forms. Disruption of CCT could cause endoplasmic reticulum (ER) stress through the accumulation of misfolded proteins. ER stress in turn initiates intracellular pathways that generate the danger signals associate with ICD. To this end, we observed that cancer cells treated with CT20p displayed alterations in PERK, a key mediator of the unfolded protein response (UPR) and translocation of Crt. As a result, CT20p-treated cancer cells were more readily phagocytosed. More importantly, NK cells more effectively killed cancer cells pre-treated with CT20p. This suggests that CT20p may stimulate NK cell cytotoxicity by inducing activating signals on cancer cells, which would greatly augment the curative effects of adoptive transfer of NK cells. In our experiments normal breast epithelial cells, macrophages or NK cells, themselves, were unaffected by CT20p treatment due reduced CCT. These studies indicate that a single molecule, CT20p, can do both the killing of cancer cells and activation of immune cells and can be combined with cellular immunotherapy (e.g. expanded NK cells) to provide a more complete protection from breast cancer recurrence and metastasis.

Citation Format: Khaled AR, Limaye A, Bassiouni R, Showalter A, Oyer J, Pandey V, Igarashi R, Altomare DA, Copik AJ. Enhancing the immunogenicity of breast cancer cells to stimulate innate immunity and augment the effects of cellular immunotherapy. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P4-04-12.

Influence of three-dimensional nanoparticle branching on the Young's modulus of nanocomposites: Effect of interface orientation

With the availability of nanoparticles with controlled size and shape, there has been renewed interest in the mechanical properties of polymer/nanoparticle blends. Despite the large number of theoretical studies, the effect of branching for nanofillers tens of nanometers in size on the elastic stiffness of these composite materials has received limited attention. Here, we examine the Young's modulus of nanocomposites based on a common block copolymer (BCP) blended with linear nanorods and nanoscale tetrapod Quantum Dots (tQDs), in electrospun fibers and thin films. We use a phenomenological lattice spring model (LSM) as a guide in understanding the changes in the Young's modulus of such composites as a function of filler shape. Reasonable agreement is achieved between the LSM and the experimental results for both nanoparticle shapes--with only a few key physical assumptions in both films and fibers--providing insight into the design of new nanocomposites and assisting in the development of a qualitative mechanistic understanding of their properties. The tQDs impart the greatest improvements, enhancing the Young's modulus by a factor of 2.5 at 20 wt.%. This is 1.5 times higher than identical composites containing nanorods. An unexpected finding from the simulations is that both the orientation of the nanoscale filler and the orientation of X-type covalent bonds at the nanoparticle-ligand interface are important for optimizing the mechanical properties of the nanocomposites. The tQD provides an orientational optimization of the interfacial and filler bonds arising from its three-dimensional branched shape unseen before in nanocomposites with inorganic nanofillers.

Differentiation of Candida albicans from non-albicans yeast directly from blood cultures by Gram stain morphology

Clusters of pseudohyphae are commonly seen on Gram stain of blood cultures from patients with Candida albicans fungemia. Whether this morphologic feature is useful for differentiating C. albicans from other yeasts has not previously been systematically evaluated. Yeast morphology on Gram stain of blood cultures from consecutive patients with fungemia detected by the Bactec automated blood culture system was prospectively assessed and correlated with the final culture-based yeast identification. The distribution of yeast in 60 consecutive patients with fungemia included Candida spp. (C. albicans 43%, Candida glabrata 28%, Candida parapsilosis 8%, Candida krusei 7%, Candida tropicalis 5%, Candida dubliniensis 2%, and Candida lusitaniae 2%), Rhodotorula mucilaginosa 2%, and Cryptococcus neoformans 3%. Upon analysis of the first positive blood culture bottle per patient, the presence of clustered pseudohyphae on Gram stain had a sensitivity, specificity, positive predictive value, and negative predictive value of 85, 97, 96, and 89%, respectively, for C. albicans. The sensitivity and specificity of aerobic vs Myco/F blood culture bottles were 96 and 95% vs 25 and 100%, p < 0.001, respectively. Inter-rater agreement for ten separate observations among five reviewers was 100%. The presence of pseudohyphae clusters by Gram stain of blood cultures is useful in distinguishing C. albicans from non-albicans yeast. Additional studies are necessary to determine the clinical impact of these findings and their validity with other blood culture systems.

Investigation of microstructural features in regenerating bone using micro computed tomography

We illustrate some of the uses of micro-computed tomography (micro-CT) to study tissue-engineered bone using a micro-CT facility for imaging and visualizing biomaterials in three dimensions (3-D). The micro-CT is capable of acquiring 3D X-ray CT images made up of 2000(3) voxels on specimens up to 5 cm in extent with resolutions down to 2 microm. This allows the 3-D structure of tissue-engineered materials to be imaged across orders of magnitude in resolution. This capability is used to examine an explanted, tissue-engineered bone material based on a polycaprolactone scaffold and autologous bone marrow cells. Imaging of the tissue-engineered bone at a scale of 1 cm and resolutions of 10 microm allows one to visualize the complex ingrowth of bone into the polymer scaffold. From a theoretical viewpoint the voxel data may also be used to calculate expected mechanical properties of the tissue-engineered implant. These observations illustrate the benefits of tomography over traditional techniques for the characterization of bone morphology and interconnectivity. As the method is nondestructive it can perform a complimentary role to current histomorphometric techniques.

Adeno-associated viral vector-mediated gene transfer results in long-term enzymatic and functional correction in multiple organs of Fabry mice

Fabry disease is a lysosomal storage disorder caused by a deficiency of the lysosomal enzyme alpha-galactosidase A (alpha-gal A). This enzyme deficiency leads to impaired catabolism of alpha-galactosyl-terminal lipids such as globotriaosylceramide (Gb3). Patients develop painful neuropathy and vascular occlusions that progressively lead to cardiovascular, cerebrovascular, and renal dysfunction and early death. Although enzyme replacement therapy and bone marrow transplantation have shown promise in the murine analog of Fabry disease, gene therapy holds a strong potential for treating this disease in humans. Delivery of the normal alpha-gal A gene (cDNA) into a depot organ such as liver may be sufficient to elicit corrective circulating levels of the deficient enzyme. To investigate this possibility, a recombinant adeno-associated viral vector encoding human alpha-gal A (rAAV-AGA) was constructed and injected into the hepatic portal vein of Fabry mice. Two weeks postinjection, alpha-gal A activity in the livers of rAAV-AGA-injected Fabry mice was 20-35% of that of the normal mice. The transduced animals continued to show higher alpha-gal A levels in liver and other tissues compared with the untouched Fabry controls as long as 6 months after treatment. In parallel to the elevated enzyme levels, we see significant reductions in Gb3 levels to near normal at 2 and 5 weeks posttreatment. The lower Gb3 levels continued in liver, spleen, and heart, up to 25 weeks with no significant immune response to the virus or alpha-gal A. Also, no signs of liver toxicity occurred after the rAAV-AGA administration. These findings suggest that an AAV-mediated gene transfer may be useful for the treatment of Fabry disease and possibly other metabolic disorders.

Propylthiouracil-induced fatal hepatic necrosis

We present a fatal case of acute submassive hepatic necrosis occurring in a 42-yr-old black woman treated for hyperthyroidism with propylthiouracil for 1 yr. Alcohol and drug abuse were ruled out and all serological tests for hepatitis A and B, cytomegalovirus, and Epstein-Barr virus infection were negative. At autopsy the liver was shrunken and presented a yellow granular appearance. Microscopy disclosed submassive necrosis with bile stasis and severe chronic inflammation, as well as mild bile duct proliferation. Although non-A, non-B hepatitis cannot be ruled out (there was no transfusion of blood or its products), this is considered to be the third fatal case and ninth instance of propylthiouracil-induced hepatic necrosis.