Adam B. Raff

The Evolving Field of Human Papillomavirus Receptor Research: a Review of Binding and Entry

ABSTRACT Human papillomaviruses (HPVs) infect epithelia and can lead to the development of lesions, some of which have malignant potential. HPV type 16 (HPV16) is the most oncogenic genotype and causes various types of cancer, including cervical, anal, and head and neck cancers. However, despite significant research, our understanding of the mechanism by which HPV16 binds to and enters host cells remains fragmented. Over several decades, many HPV receptors and entry pathways have been described. This review puts those studies into context and offers a model of HPV16 binding and entry as a framework for future research. Our model suggests that HPV16 binds to heparin sulfate proteoglycans (HSPGs) on either the epithelial cell surface or basement membrane through interactions with the L1 major capsid protein. Growth factor receptors may also become activated through HSPG/growth factor/HPV16 complexes that initiate signaling cascades during early virion-host cell interactions. After binding to HSPGs, the virion undergoes conformational changes, leading to isomerization by cyclophilin B and proprotein convertase-mediated L2 minor capsid protein cleavage that increases L2 N terminus exposure. Along with binding to HSPGs, HPV16 binds to α6 integrins, which initiate further intracellular signaling events. Following these primary binding events, HPV16 binds to a newly identified L2-specific receptor, the annexin A2 heterotetramer. Subsequently, clathrin-, caveolin-, lipid raft-, flotillin-, cholesterol-, and dynamin-independent endocytosis of HPV16 occurs.

The S100A10 Subunit of the Annexin A2 Heterotetramer Facilitates L2-Mediated Human Papillomavirus Infection

Mucosotropic, high-risk human papillomaviruses (HPV) are sexually transmitted viruses that are causally associated with the development of cervical cancer. The most common high-risk genotype, HPV16, is an obligatory intracellular virus that must gain entry into host epithelial cells and deliver its double stranded DNA to the nucleus. HPV capsid proteins play a vital role in these steps. Despite the critical nature of these capsid protein-host cell interactions, the precise cellular components necessary for HPV16 infection of epithelial cells remains unknown. Several neutralizing epitopes have been identified for the HPV16 L2 minor capsid protein that can inhibit infection after initial attachment of the virus to the cell surface, which suggests an L2-specific secondary receptor or cofactor is required for infection, but so far no specific L2-receptor has been identified. Here, we demonstrate that the annexin A2 heterotetramer (A2t) contributes to HPV16 infection and co-immunoprecipitates with HPV16 particles on the surface of epithelial cells in an L2-dependent manner. Inhibiting A2t with an endogenous annexin A2 ligand, secretory leukocyte protease inhibitor (SLPI), or with an annexin A2 antibody significantly reduces HPV16 infection. With electron paramagnetic resonance, we demonstrate that a previously identified neutralizing epitope of L2 (aa 108–120) specifically interacts with the S100A10 subunit of A2t. Additionally, mutation of this L2 region significantly reduces binding to A2t and HPV16 pseudovirus infection. Furthermore, downregulation of A2t with shRNA significantly decreases capsid internalization and infection by HPV16. Taken together, these findings indicate that A2t contributes to HPV16 internalization and infection of epithelial cells and this interaction is dependent on the presence of the L2 minor capsid protein.

Prostate stem cell antigen: A prospective therapeutic and diagnostic target

The development of novel clinical tools to combat cancer is an intense field of research and recent efforts have been directed at the identification of proteins that may provide diagnostic, prognostic and/or therapeutic applications due to their restricted expression. To date, a number of protein candidates have emerged as potential clinical tools in the treatment of prostate cancer. Discovered over ten year ago, prostate stem cell antigen (PSCA) is a cell surface antigen that belongs to the Ly-6/Thy-1 family of glycosylphosphatidylinositol-anchored proteins. PSCA is highly overexpressed in human prostate cancer, with limited expression in normal tissues, making it an ideal target for both diagnosis and therapy. Several studies have now clearly correlated the expression of PSCA with relevant clinical benchmarks, such as Gleason score and metastasis, while others have demonstrated the efficacy of PSCA targeting in treatment through various modalities. The purpose of this review is to present the current body of knowledge about PSCA and its potential role in the treatment of human prostate cancer.

A paradigm shift in therapeutic vaccination of cancer patients : the need to apply therapeutic vaccination strategies in the preventive setting

Summary: An extraordinary variety of potential therapeutic vaccine strategies directed against a wide variety of tumor antigens has been explored in clinical trials. To date, none of these cancer immunotherapies have been approved by the Food and Drug Administration for use in humans. A significant problem is that the vast majority of such clinical trials are carried out in patients with advanced or metastatic cancer. The immune systems of these patients are considerably compromised as a result of tumor‐ and treatment‐mediated immunosuppression. Even in cases where patients are immunized in the adjuvant setting, where there is minimal residual disease, vaccines directed against tumor‐associated antigens have failed to mediate eradication of tumors in the overwhelming majority of cases. Recently, we and others have experimented with administering therapeutic cancer vaccines in the preventive setting. This is achieved by vaccinating at the earliest possible stage of carcinogenesis. These studies have demonstrated that early vaccination is extremely effective in eliciting an anti‐tumor immune response that leads to unprecedented improvements in the survival of mice that spontaneously develop cancer. Certain human cancers, notably prostate adenocarcinoma and cervical cancer, can currently be detected at very early stages of carcinogenesis. Therapeutic vaccines are available for these diseases, opening up the possibility of administering vaccinations early to patients diagnosed with pre‐malignant lesions to halt disease progression. In addition, new technologies have become available in the past decade that will soon yield very sensitive and specific diagnostic tests for a plethora of other cancers. Earlier detection of these cancers, combined with existing vaccines directed against them, will soon make them targets for therapeutic vaccination in the preventive setting. The ability to immunize patients at the very earliest stages of carcinogenesis, when they have fully competent immune systems, has the potential to cause a paradigm shift in how therapeutic cancer vaccines are tested and used clinically.

Cellulitis: A Review

IMPORTANCE Cellulitis is an infection of the deep dermis and subcutaneous tissue, presenting with expanding erythema, warmth, tenderness, and swelling. Cellulitis is a common global health burden, with more than 650,000 admissions per year in the United States alone. OBSERVATIONS In the United States, an estimated 14.5 million cases annually of cellulitis account for

Reversal of human papillomavirus-specific T cell immune suppression through TLR agonist treatment of Langerhans cells exposed to human papillomavirus type 16.

3.7 billion in ambulatory care costs alone. The majority of cases of cellulitis are nonculturable and therefore the causative bacteria are unknown. In the 15% of cellulitis cases in which organisms are identified, most are due to β-hemolytic Streptococcus and Staphylococcus aureus. There are no effective diagnostic modalities, and many clinical conditions appear similar. Treatment of primary and recurrent cellulitis should initially cover Streptococcus and methicillin-sensitive S. aureus, with expansion for methicillin-resistant S. aureus (MRSA) in cases of cellulitis associated with specific risk factors, such as athletes, children, men who have sex with men, prisoners, military recruits, residents of long-term care facilities, those with prior MRSA exposure, and intravenous drug users. Five days of treatment is sufficient with extension if symptoms are not improved. Addressing predisposing factors can minimize risk of recurrence. CONCLUSIONS AND RELEVANCE The diagnosis of cellulitis is based primarily on history and physical examination. Treatment of uncomplicated cellulitis should be directed against Streptococcus and methicillin-sensitive S. aureus. Failure to improve with appropriate first-line antibiotics should prompt consideration for resistant organisms, secondary conditions that mimic cellulitis, or underlying complicating conditions such as immunosuppression, chronic liver disease, or chronic kidney disease.

A Major Role for the Minor Capsid Protein of Human Papillomavirus Type 16 in Immune Escape

Human papillomavirus (HPV) type 16 infects the epithelial layer of cervical mucosa and is causally associated with the generation of cervical cancer. Langerhans cells (LC) are the resident APCs at the site of infection and therefore are responsible for initiating an immune response against HPV16. On the contrary, LC exposed to HPV16 do not induce a specific T cell immune response, which leads to the immune evasion of HPV16. Demonstrating that TLR7 and TLR8 are expressed on human LC, we hypothesized that imidazoquinolines would activate LC exposed to HPV16, leading to the induction of an HPV16-specific cell-mediated immune response. Surprisingly, both phenotypic and functional hallmarks of activation are not observed when LC are exposed to HPV16 virus-like particles and treated with imiquimod (TLR7 agonist). However, we found that LC are activated by 3M-002 (TLR8 agonist) and resiquimod (TLR8/7 agonist). LC exposed to HPV16 virus-like particles and subsequently treated with 3M-002 or resiquimod highly up-regulate surface activation markers, secrete proinflammatory cytokines and chemokines, induce CCL21-directed migration, and initiate an HPV16-specific CD8+ T cell response. These data strongly indicate that 3M-002 and resiquimod are promising therapeutics for treatment of HPV infections and HPV-induced cervical lesions.

Costs and Consequences Associated With Misdiagnosed Lower Extremity Cellulitis

High-risk human papillomavirus (HPV) infection of the cervical epithelium is causally linked with the generation of cervical cancer. HPV does not activate Langerhans cells (LC), the APC at the site of infection, leading to immune evasion. The HPV protein responsible for inducing this immune escape has not been determined. We demonstrate that LC exposed to the minor capsid protein L2 in HPV16L1L2 virus-like particles do not phenotypically or functionally mature. However, HPV16L1 virus-like particles significantly induce activation of LC. Our data suggest that the L2 protein plays a specific role in the induction of this immune escape of HPV16 through the manipulation of LC. This novel function is the first immune modulating action attributed to the L2 protein and adds significantly to our understanding of the mechanism of HPV immune escape.

Inhibition of Langerhans Cell Maturation by Human Papillomavirus Type 16: A Novel Role for the Annexin A2 Heterotetramer in Immune Suppression

Importance Inflammatory dermatoses of the lower extremity are often misdiagnosed as cellulitis (aka “pseudocellulitis”) and treated with antibiotics and/or hospitalization. There is limited data on the cost and complications from misdiagnosed cellulitis. Objective To characterize the national health care burden of misdiagnosed cellulitis in patients admitted for treatment of lower extremity cellulitis. Design, Setting, and Participants Cross-sectional study using patients admitted from the emergency department (ED) of a large urban hospital with a diagnosis of lower extremity cellulitis between June 2010 and December 2012. Patients who were discharged with a diagnosis of cellulitis were categorized as having cellulitis, while those who were given an alternative diagnosis during the hospital course, on discharge, or within 30 days of discharge were considered to have pseudocellulitis. A literature review was conducted for calculation of large-scale costs and complication rates. We obtained national cost figures from the Medical Expenditure Panel Survey (MEPS), provided by the Agency for Healthcare Research and Quality (AHRQ) for 2010 to calculate the hospitalization costs per year attributed to misdiagnosed lower extremity pseudocellulitis. Exposures The exposed group was composed of patients who presented to and were admitted from the ED with a diagnosis of lower extremity cellulitis. Main Outcomes and Measures Patient characteristics, hospital course, and complications during and after hospitalization were reviewed for each patient, and estimates of annual costs of misdiagnosed cellulitis in the United States. Results Of 259 patients, 79 (30.5%) were misdiagnosed with cellulitis, and 52 of these misdiagnosed patients were admitted primarily for the treatment of cellulitis. Forty-four of the 52 (84.6%) did not require hospitalization based on ultimate diagnosis, and 48 (92.3%) received unnecessary antibiotics. We estimate cellulitis misdiagnosis leads to 50 000 to 130 000 unnecessary hospitalizations and

A predictive model for diagnosis of lower extremity cellulitis: A cross-sectional study

195 million to