PhD candidate at University of Wisconsin and study the role of papillomaviruses in skin cancer
You sure want to use that sunscreen!
I work on everyone’s favorite embarrassing topic - Warts.
A very reliable therapy, according to Louisiana Voodoo, is that if you rub a potato on a wart, burry the potato, the wart will go away. If only that’s how viruses worked!
Warts (also referred to as papillomas) - are caused by a really small, cancer-causing virus, called the human papillomavirus or HPV. There are more than 140 sub-types of HPVs that can cause genital or skin warts that can, in some instances, progress to cancer. The HPV-vaccine protects us from at least 6 types of HPVs that cause genital cancer. What about the remaining 134 types? And that’s where my thesis comes in – I am trying to understand the biology of skin-related HPVs and how they cause cancers?
Research progress has been hampered primarily because HPVs are species specific! So a human papillomavirus infects only humans and a porcupine papillomavirus, that actually does exist, infects only a porcupine. When I started my PhD, the first ever papillomavirus that could infect a mouse was discovered. After all these years, we can now study a papillomavirus infection in a mouse model.
In my thesis work, I learnt something unique about MusPV – It caused skin warts only in animals genetically modified to have defective immune system. And absolutely no disease in animals with an intact immune system. In one of my experiments, I exposed virus-infected mice with a healthy immune system, to UV- the same ultraviolet radiation spectra found in the sunlight. Now these healthy mice that did not develop disease previously, started getting warts and in some cases even cancer.
This was a significant observation as it has been hypothesized for years, that individuals chronically exposed to sunlight may develop HPV-associated skin cancers. But no-one really understands why? So with this UV-infection model in mice I have now discovered that UV actually causes defects in the immune system of these mice preventing them to fight off the infection.
So how does my thesis fit in the big picture: by understanding the mechanism of disease we can develop a therapy for skin cancers. I’m hopeful that very soon we will be able to build a vaccine that can prevent skin cancers due to HPVs.
Abstract: Exposure to ultraviolet radiation (UVR) suppresses immunity by complex pathways, initiated by chromophores located in the skin and ending with the generation of specific subsets of T and B regulatory cells. The primary and memory (recall) immune response to a wide variety of antigens, including microorganisms, can be reduced by UVR, leading to the possibility that the efficacy of vaccination could be similarly reduced. A limited number of animal models of vaccination demonstrate that this may indeed be the case. The situation in human subjects has not been rigorously assessed but there are indications from a variety of sources that UVR adversely affects the immune responses to several vaccines. These studies are reviewed and the implications for vaccine administration discussed. As vaccination represents a major public health measure world-wide for the control of an increasing number of common infections, it is important to maximise its efficacy; therefore further evaluation of UVR in the context of vaccination is required and warranted.
Pub.: 30 Jun '11, Pinned: 16 Aug '17
Abstract: Cutaneous squamous cell carcinoma (cuSCC) comprises 15–20% of all skin cancers, accounting for over 700,000 cases in USA annually. Most cuSCC arise in association with a distinct precancerous lesion, the actinic keratosis (AK). To identify potential targets for molecularly targeted chemoprevention, here we perform integrated cross-species genomic analysis of cuSCC development through the preneoplastic AK stage using matched human samples and a solar ultraviolet radiation-driven Hairless mouse model. We identify the major transcriptional drivers of this progression sequence, showing that the key genomic changes in cuSCC development occur in the normal skin to AK transition. Our data validate the use of this ultraviolet radiation-driven mouse cuSCC model for cross-species analysis and demonstrate that cuSCC bears deep molecular similarities to multiple carcinogen-driven SCCs from diverse sites, suggesting that cuSCC may serve as an effective, accessible model for multiple SCC types and that common treatment and prevention strategies may be feasible.
Pub.: 30 Aug '16, Pinned: 16 Aug '17
Abstract: Viruses make up a major component of the human microbiota but are poorly understood in the skin, our primary barrier to the external environment. Viral communities have the potential to modulate states of cutaneous health and disease. Bacteriophages are known to influence the structure and function of microbial communities through predation and genetic exchange. Human viruses are associated with skin cancers and a multitude of cutaneous manifestations. Despite these important roles, little is known regarding the human skin virome and its interactions with the host microbiome. Here we evaluated the human cutaneous double-stranded DNA virome by metagenomic sequencing of DNA from purified virus-like particles (VLPs). In parallel, we employed metagenomic sequencing of the total skin microbiome to assess covariation and infer interactions with the virome. Samples were collected from 16 subjects at eight body sites over 1 month. In addition to the microenviroment, which is known to partition the bacterial and fungal microbiota, natural skin occlusion was strongly associated with skin virome community composition. Viral contigs were enriched for genes indicative of a temperate phage replication style and also maintained genes encoding potential antibiotic resistance and virulence factors. CRISPR spacers identified in the bacterial DNA sequences provided a record of phage predation and suggest a mechanism to explain spatial partitioning of skin phage communities. Finally, we modeled the structure of bacterial and phage communities together to reveal a complex microbial environment with a Corynebacterium hub. These results reveal the previously underappreciated diversity, encoded functions, and viral-microbial dynamic unique to the human skin virome.To date, most cutaneous microbiome studies have focused on bacterial and fungal communities. Skin viral communities and their relationships with their hosts remain poorly understood despite their potential to modulate states of cutaneous health and disease. Previous studies employing whole-metagenome sequencing without purification for virus-like particles (VLPs) have provided some insight into the viral component of the skin microbiome but have not completely characterized these communities or analyzed interactions with the host microbiome. Here we present an optimized virus purification technique and corresponding analysis tools for gaining novel insights into the skin virome, including viral "dark matter," and its potential interactions with the host microbiome. The work presented here establishes a baseline of the healthy human skin virome and is a necessary foundation for future studies examining viral perturbations in skin health and disease.
Pub.: 23 Oct '15, Pinned: 16 Aug '17
Abstract: Accumulating evidence suggests that cutaneous human papillomavirus (HPV) infection is associated with non-melanoma skin cancer (NMSC). Little is known about the natural history of cutaneous HPV. A sub-cohort of 209 men with no NMSC history, initially enrolled in the HPV infection in men (HIM) study, were followed for a median of 12.6 months. Epidemiological data were collected through self-administered questionnaires. Cutaneous HPV DNA was measured in normal skin swabs (SS) and eyebrow hairs (EB) for 25 and 16 HPV types in genera β and γ, respectively. Any β HPV infection was more prevalent in SS (67.3%) compared to EB (56.5%, p = 0.04). Incidence in SS was higher than 20 per 1,000 person-months for HPV types 4, 5, 23, 38 and 76. Median duration of persistence of β and γ HPV infection was 8.6 and 6.1 months in EB, respectively, and 11.3 months and 6.3 months, in SS, respectively. Older age (>44 years vs. 18-30 years) was significantly associated with prevalent (SS OR = 3.0, 95% CI = 1.2-7.0) and persistent β HPV infection (EB OR = 6.1, 95% CI = 2.6-14.1). History of blistering sunburn was associated with prevalent (OR = 2.8, 95% CI = 1.3-5.8) and persistent (OR = 2.3, 95% CI = 1.2-4.6) β HPV infection in SS. Cutaneous HPV is highly prevalent in men, with age and blistering sunburn being significant risk factors for cutaneous β HPV infection.
Pub.: 10 Sep '14, Pinned: 15 Jul '17
Abstract: Human skin apart from functioning as a physical barricade to stop the entry of pathogens, also hosts innumerable commensal organisms. The skin cells and the immune system constantly interact with microbes, to maintain cutaneous homeostasis, despite the challenges offered by various environmental factors. A major environmental factor affecting the skin is ultraviolet radiation (UV-R) from sunlight. UV-R is well known to modulate the immune system, which can be both beneficial and deleterious. By targeting the cells and molecules within skin, UV-R can trigger the production and release of antimicrobial peptides, affect the innate immune system and ultimately suppress the adaptive cellular immune response. This can contribute to skin carcinogenesis and the promotion of infectious agents such as herpes simplex virus and possibly others. On the other hand, a UV-established immunosuppressive environment may protect against the induction of immunologically mediated skin diseases including some of photodermatoses such as polymorphic light eruption. In this article, we share our perspective about the possibility that UV-induced immune suppression may alter the landscape of the skin's microbiome and its components. Alternatively, or in concert with this, direct UV-induced DNA and membrane damage to the microbiome may result in pathogen associated molecular patterns (PAMPs) that interfere with UV-induced immune suppression.
Pub.: 26 Aug '16, Pinned: 15 Jul '17
Abstract: Human papillomaviruses are causally associated with 5% of human cancers. The recent discovery of a papillomavirus (MmuPV1) that infects laboratory mice provides unique opportunities to study the life cycle and pathogenesis of papillomaviruses in the context of a genetically manipulatable host organism. To date, MmuPV1-induced disease has been found largely to be restricted to severely immunodeficient strains of mice. In this study, we report that ultraviolet radiation (UVR), specifically UVB spectra, causes wild-type strains of mice to become highly susceptible to MmuPV1-induced disease. MmuPV1-infected mice treated with UVB develop warts that progress to squamous cell carcinoma. Our studies further indicate that UVB induces systemic immunosuppression in mice that correlates with susceptibility to MmuPV1-associated disease. These findings provide new insight into how MmuPV1 can be used to study the life cycle of papillomaviruses and their role in carcinogenesis, the role of host immunity in controlling papillomavirus-associated pathogenesis, and a basis for understanding in part the role of UVR in promoting HPV infection in humans.
Pub.: 01 Jun '16, Pinned: 15 Jul '17
Abstract: Cutaneous human papillomavirus (HPV) has been widely detected in healthy skin. Previous studies have found that UV radiation can activate several HPV types, and a possible role for cutaneous HPV in the development of non-melanoma skin cancer has been suggested. This study investigated the prevalence and type-spectrum of cutaneous HPV in relation to UV radiation by studying forehead skin swab samples from 50 healthy males frequently exposed to the sun and 50 healthy males who were not frequently exposed to the sun. A questionnaire including ethnic background of the participants, history of cancers and a self-assessment of sun-exposure was also conducted and analysed. PCR with the FAP primer pair was carried out to detect HPV DNA in samples. HPV prevalence was higher in individuals who spent more time outdoors and in individuals with a history of skin cancers (P=0.044 and P=0.04, respectively). Furthermore, individuals wearing sunglasses as a means of sun protection had a lower prevalence of HPV (P=0.018). Interestingly, HPV-76 was only detected in the group without frequent sun-exposure (P=0.001). These results suggest that increased UV radiation exposure may be a factor leading to a difference in prevalence of cutaneous HPV types.
Pub.: 22 Oct '08, Pinned: 15 Jul '17