Faculty Bibliography

In this issue of Neuron, Yuzwa et al. (2016) identify secreted factors that influence the cell fates of embryonic neural progenitor cells. Surprisingly, the major contributors are trophic factors from the GDNF family and a cytokine, interferon-gamma. Advanced analysis of proteomic and transcriptome data discovered ligand receptors that influence cell-cell communication.

Advances in financial engineering are radically reshaping the biomedical marketplace. For instance, new methods of pooling diversified drug development programs by placing them in a special purpose vehicle (SPV) have been proposed to create a securitized cancer megafund allowing for debt and equity participation. In this study, we perform theoretical and numerical simulations that highlight the role of empirical validation of the projects comprising a cancer megafund. We quantify the degree to which the deliberately designed structure of derivatives and investments is key to its liquidity. Research megafunds with comprehensive in silico and laboratory validation protocols and ability to issue both debt, and equity as well as hybrid financial products may enable conservative investors including pension funds and sovereign government funds to profit from unique securitization opportunities. Thus, while hedging investor's longevity risk, such well-validated megafunds will contribute to health, well being and longevity of the global population.

In a typical workplace, organizational policies and their compliance requirements set the stage upon which the behavioral patterns of individual agents evolve. The agents"™ personal utilities, access to information, and strategic deceptions shape the signaling systems of an intricate information-asymmetric game, thus mystifying assessment and management of organizational risks, which are primarily due to unintentional insider threats. Compliance games, as discussed here, model a rudimentary version of this signaling game between a sender (employee) and a receiver (organization). The analysis of these games"™ equilibria as well as their dynamics in repeated game settings illuminate the effectiveness or risks of an organizational policy. These questions are explored via a repeated and agent-based simulation of compliance signaling games, leading to the following: (1) a simple but broadly applicable model for interactions between sender agents (employees) and receiver agents (principals in the organization), (2) an investigation of how the game theoretic approach yields the plausible dynamics of compliance, and (3) design of experiments to estimate parameters of the systems: evolutionary learning rates of agents, the efficacy of auditing using a trembling hand strategy, effects of non-stationary and multiple principal agents, and ultimately, the robustness of the system under perturbation of various related parameters (costs, penalties, benefits, etc.). The paper concludes with a number of empirical studies, illustrating a battery of compliance games under varying environments designed to investigate agent based learning, system control, and optimization. The studies indicate how agents through limited interactions described by behavior traces may learn and optimize responses to a stationary defense, expose sensitive parameters and emergent properties and indicate the possibility of controlling interventions which actuate game parameters. We believe that the work is of practical importance"”for example, in constraining the vulnerability surfaces arising from compliance games.

Rhomboids are ubiquitous intramembrane serine proteases involved in various signaling pathways. While the high-resolution structures of the Escherichia coli rhomboid GlpG with various inhibitors revealed an active site comprised of a serine-histidine dyad and an extensive oxyanion hole, the molecular details of rhomboid catalysis were unclear because substrates are unknown for most of the family members. Here we used the only known physiological pair of AarA rhomboid with its psTatA substrate to decipher the contribution of catalytically important residues to the reaction rate enhancement. An MD-refined homology model of AarA was used to identify residues important for catalysis. We demonstrated that the AarA active site geometry is strict and intolerant to alterations. We probed the roles of H83 and N87 oxyanion hole residues and determined that substitution of H83 either abolished AarA activity or reduced the transition state stabilization energy (DeltaDeltaGdouble dagger) by 3.1 kcal/mol; substitution of N87 decreased DeltaDeltaGdouble dagger by 1.6-3.9 kcal/mol. Substitution M154, a residue conserved in most rhomboids that stabilizes the catalytic general base, to tyrosine, provided insight into the mechanism of nucleophile generation for the catalytic dyad. This study provides a quantitative evaluation of the role of several residues important for hydrolytic efficiency and oxyanion stabilization during intramembrane proteolysis.

OBJECTIVE: Netrin-1 is a chemorepulsant and matrix protein expressed during and required for osteoclast differentiation, which also plays a role in inflammation by preventing macrophage egress. Because wear particle-induced osteolysis requires osteoclast-mediated destruction of bone, we hypothesised that blockade of Netrin-1 or Unc5b, a receptor for Netrin-1, may diminish this pathological condition. METHODS: C57BL/6 mice, 6-8 weeks old, had 3 mg of ultrahigh-molecular-weight polyethylene particles implanted over the calvaria and then received 10 microg of monoclonal antibodies for Netrin-1 or its receptors, Unc5b and deleted in colon cancer (DCC), injected intraperitoneally on a weekly basis. After 2 weeks, micro-computed tomography and histology analysis were performed. Netrin-1 expression was analysed in human tissue obtained following primary prosthesis implantation or after prosthesis revision for peri-implant osteolysis and aseptic implant loosening. RESULTS: Weekly injection of anti-Netrin-1 or anti-Unc5b-antibodies significantly reduced particle-induced bone pitting in calvaria exposed to wear particles (46+/-4% and 49+/-3% of control bone pitting, respectively, p<0.001) but anti-DCC antibody did not affect inflammatory osteolysis (80+/-7% of control bone pitting, p=ns). Anti-Netrin-1 or anti-Unc5b, but not anti-DCC, antibody treatment markedly reduced the inflammatory infiltrate and the number of tartrate resistance acid phosphatase (TRAP)-positive osteoclasts (7+/-1, 4+/-1 and 14+/-1 cells/high power field (hpf), respectively, vs 12+/-1 cells/hpf for control, p<0.001), with no significant changes in alkaline phosphatase-positive osteoblasts on bone-forming surfaces in any antibody-treated group. Netrin-1 immunostaining colocalised with CD68 staining for macrophages. The peri-implant tissues of patients undergoing prosthesis revision surgery showed an increase in Netrin-1 expression, whereas there was little Netrin-1 expression in soft tissues removed at the time of primary joint replacement. CONCLUSIONS: These results demonstrate a unique role for Netrin-1 in osteoclast biology and inflammation and may be a novel target for prevention/treatment of inflammatory osteolysis.

Selective serotonin reuptake inhibitors (SSRIs) are a class of antidepressants that are utilized to treatmajor depressive disorders and anxiety disorders; SSRIs are the most widely used antidepressants worldwide.3 Past literature on SSRIs have documented that use of SSRIs reduce bone formation thus increasing the risk of bone fracture. Inhibiting the reuptake of 5-HTs results in increased osteoclast differentiation and inhibition of osteoblast proliferation, leading to an overall decrease in bone mass and bone mineral density. 1Recent studies have suggested that use of SSRIs is associated with increased risk of dental implant failure, although other studies involving bone loss and remodeling have reported conflicting results. In addition to SSRIs, proton- proton inhibitors and anti-epileptic drugs have also been implicated in impaired bone remodeling. We conducted a retrospective study on patients who completed dental implant therapy from December 2007 to January 2016 at a single institution. A total of 510 dental implants (167 implants placed in 29 patients using SSRIs) placed in 108 male patients were used to assess the risk associated with the use of SSRI. The data was analyzed with a multivariate analysis and linear regression model. Osseointegration is defined as a direct structural and functional connection between ordered living bone and the surface of a load-carrying implant, that is critical for implant stability.2 In order for implants to be considered successful, they must be fully osseointegrated with the bone and provide function. Implant failure is defined as presenting with one or more of the following: clinical signs of mobility, pain, infection, total loss of implant, radiographic bone loss and/or peri-apical pathology. The results of our study show that in patients taking an SSRI at the time of dental implant therapy, 10 implants failed and 157 were successful (5.99% failure rate), while in those who were not taking an SSRI, 20 implants failed and 323 were successful (5.83% failure rate). We found no association between SSRI and dental implant failure risk (RR = 1.03; 95% confidence interval, 0.4918-2.1443; p = 0.9436). A secondary outcome that was associated with increased failure rate was smoking habits (p = 0.03), which is in agreement with previous studies. Additionally, we did not find a dose-dependent risk of dental implant failure in patients who were taking a low-moderate vs. moderate- high dose of SSRIs (RR = 1.91, 95% confidence interval, 0.4201 -8.6981; p = 0.40) The study assessed the use of proton- pump inhibitors and anti-epileptic drugs in the above patients, demonstrating that there was no associated risk of implant failure (p =0.93; p = 0.84, respectively). Our results conclude that treatment with SSRIs is not associated with an increased failure rate of osseointegration of dental implants, which is not in agreement with previously reported studies. 4

OBJECTIVES: Autoantibodies against tumor-associated antigens (TAAs) identified in patients with advanced lung cancer may be detected in subjects with early lung cancer or even predate the diagnosis. The purpose of this study is to address the temporal relationship between lung cancer development and serum autoantibody response. MATERIALS AND METHODS: Two cohorts of patients with newly diagnosed lung cancer were included. The first cohort included 90 sera from patients with lung cancer (Stages I-III) and 89 normal control sera. In the second cohort, 93 serial serum samples from 25 patients with CT-scan screen-detected stage I lung cancer were collected before the diagnosis of lung cancer (average 32 months) and 56 controls were matched on age, gender, and smoking. Autoantibody levels were measured by immunoassay. RESULTS: Measurement of autoantibodies against seven TAAs (14-3-3zeta, c-Myc, MDM2, NPM1, p16, p53 and cyclin B1) individually could discriminate lung cancer patients from normal individuals in the first cohort and the area under curve (AUC) was 0.863 based on a panel of seven autoantibodies, with sensitivity of 68.9% and specificity of 79.5%. Autoantibodies in serial pre-diagnostic serum samples against the same panel of seven TAAs were detected prior to lung cancer diagnosis with sensitivity of 76.0% and specificity of 73.2% (AUC) (95%CI): 0.885 (0.797-0.973)). Elevated autoantibody levels could be detected greater than four years prior to lung cancer diagnosis. CONCLUSION: A panel of seven TAAs may enhance the early detection of lung cancer, consistent with a humoral immune response to TAAs that can be detected months to years prior to the diagnosis.

Oral melanoacanthoma (MA) is a rare, benign pigmented lesion that presents as a painless, rapidly growing, brown-black macular lesion that commonly affects the buccal mucosa in areas that are subject to chronic trauma/irritation.1,2 MA is commonly seen in the third and fourth decades of life and primarily affects blacks with a strong female predilection.3,4 Histopathologically, the lesions exhibit proliferation of keratinocytes and dendritic melanocytes.5 This report includes two cases of oral melanoacanthoma and a review of the literature. Case 1: A 43-year-old black female presented with a slowly enlarging pigmented lesion on the right buccal mucosa. The patient did not recall any known trauma to the area or previous infection and reported that the lesion was painless but had a gradually increased in size. Oral examination revealed a 2.0 x 2.0 cm. brown macule on the right buccal mucosa. A punch biopsy was taken of the pigmented area. The tissue was placed in 10% formalin and submitted for microscopic examination. The tissue was stained with hematoxylin and eosin and exhibited acanthotic, stratified squamous epithelium with dendritic melanocytes dispersed throughout the epithelium consistent with a diagnosis of melanoacanthoma. Case 2: A-35 year-old black female presented with a rapidly growing pigmented lesion on the left buccal mucosa. Two years prior to presentation the patient had noted a brown lesion on the buccal mucosa adjacent to a fractured tooth. The lesion remained unchanged and asymptomatic for approximately two years. One week prior to presentation, the patient noted that the lesion was enlarging, but remained painless. Oral examination revealed a 1.5 x 1.5 cm. brown macule surrounded by erythema on the left buccal mucosa adjacent to a fractured tooth. A punch biopsy was taken that included both the pigmented and erythematous areas. The tissue was placed in 10% formalin and submitted for microscopic examination. The tissue was stained with hematoxylin and eosin and exhibited similar histopathologic features to the previous case. Immunohistochemical staining with S-100 and Melan-A dramatically demonstrated the dendritic melanocytes. Review of the literature revealed a total of 50 cases of oral melanoacanthoma. These lesions were reported in black females on the buccal mucosa with subsequent resolution. The cases here demonstrate similar clinical features and age at presentation to previously reported cases. The pathogenesis of oral MA remains unclear, however, most studies suggest this is a reactive process due to chronic irritation.2 Oral MA may regress following biopsy and no surgical intervention is required due to its selfresolving quality.5

Neurofilaments are uniquely complex among classes of intermediate filaments in being composed of four subunits (NFL, NFM, NFH and alpha-internexin in the CNS) that differ in structure, regulation, and function. Although neurofilaments have been traditionally viewed as axonal structural components, recent evidence has revealed that distinctive assemblies of neurofilament subunits are integral components of synapses, especially at postsynaptic sites. Within the synaptic compartment, the individual subunits differentially modulate neurotransmission and behavior through interactions with specific neurotransmitter receptors. These newly uncovered functions suggest that alterations of neurofilament proteins not only underlie axonopathy in various neurological disorders but also may play vital roles in cognition and neuropsychiatric diseases. Here, we review evidence that synaptic neurofilament proteins are a sizable population in the CNS and we advance the concept that changes in the levels or post-translational modification of individual NF subunits contribute to synaptic and behavioral dysfunction in certain neuropsychiatric conditions.

BACKGROUND: Patients with atopic dermatitis (AD) are prone to skin infections, with microbes such as Staphylococcus aureus suspected of contributing to pathogenesis. Bleach baths might improve AD by reducing skin microbial burden. OBJECTIVE: We sought to characterize the microbiota of lesional and nonlesional skin in young children with AD and control subjects and compare changes after treatment with a topical corticosteroid (TCS) alone or TCS + dilute bleach bath. METHODS: In a randomized, placebo-controlled, single-blinded clinical trial in 21 children with AD and 14 healthy children, lesional and nonlesional AD skin was examined at baseline and after 4-week treatment with TCS alone or TCS plus bleach bath. Microbial DNA was extracted for quantitative polymerase chain reaction of predominant genera and 16S rRNA sequencing. RESULTS: At baseline, densities of total bacteria and Staphylococcus, including Staphylococcus aureus, were significantly higher at the worst AD lesional site than nonlesional (P = .001) or control (P < .001) skin; bacterial communities on lesional and nonlesional AD skin significantly differed from each other (P = .04) and from control (P < .001). After TCS + bleach bath or TCS alone, bacterial compositions on lesional skin normalized (P < .0001), resembling nonlesional skin, with microbial diversity restored to control skin levels. LIMITATIONS: The 4-week time period and/or the twice-weekly baths may not have been sufficient for additional impact on the cutaneous microbiome. More detailed sequencing may allow better characterization of the distinguishing taxa with bleach bath treatment. CONCLUSIONS: Treatment with a TCS cream suffices to normalize the cutaneous microbiota on lesional AD; after treatment, bacterial communities on lesional skin resemble nonlesional skin but remain distinct from control.