HPV8-induced STAT3 activation led keratinocyte stem cell expansion in human actinic keratoses.

Despite epidermal turnover, the skin is host to a complex array of microbes including viruses, such as the human papillomavirus (HPV), which must infect and manipulate skin keratinocyte stem cells (KSC) to survive. This crosstalk between the virome and KSC populations remains largely unknown. Here, we investigated the effect of HPV8 on KSCs using various mouse models. We observed that the HPV8 early region gene E6 specifically caused Lrig1+ hair follicle junctional zone KSC proliferation and expansion, which would facilitate viral transmission. Within Lrig1+ KSCs specifically, HPV8 E6 bound intracellular p300 to phosphorylate the STAT3 transcriptional regulatory node. This induces ΔNp63 expression, resulting in KSC expansion into the overlying epidermis. HPV8 was associated with 70% of human actinic keratoses (AK). Together these results define the "hit and run" mechanism for HPV8 in human actinic keratosis as an expansion of KSCs, which lacks melanosome protection and is thus susceptible to sun-light-induced malignant transformation.

Efficient wastewater sample filtration improves the detection of SARS-CoV-2 variants: An extensive analysis based on sequencing parameters.

During the SARS-CoV-2 pandemic, many countries established wastewater (WW) surveillance to objectively monitor the level of infection within the population. As new variants continue to emerge, it has become clear that WW surveillance is an essential tool for the early detection of variants. The EU Commission published a recommendation suggesting an approach to establish surveillance of SARS-CoV-2 and its variants in WW, besides specifying the methodology for WW concentration and RNA extraction. Therefore, different groups have approached the issue with different strategies, mainly focusing on WW concentration methods, but only a few groups highlighted the importance of prefiltering WW samples and/or purification of RNA samples. Aiming to obtain high-quality sequencing data allowing variants detection, we compared four experimental conditions generated from the treatment of: i) WW samples by WW filtration and ii) the extracted RNA by DNase treatment, purification and concentration of the extracted RNA. To evaluate the best condition, the results were assessed by focusing on several sequencing parameters, as the outcome of SARS-CoV-2 sequencing from WW is crucial for variant detection. Overall, the best sequencing result was obtained by filtering the WW sample. Moreover, the present study provides an overview of some sequencing parameters to consider when optimizing a method for monitoring SARS-CoV-2 variants from WW samples, which can also be applied to any sample preparation methodology.

Enhanced Spontaneous Skin Tumorigenesis and Aberrant Inflammatory Response to UVB Exposure in Immunosuppressed Human Papillomavirus Type 8‒Transgenic Mice.

Human papillomaviruses (HPVs) from the beta genus are commensal viruses of the skin usually associated with asymptomatic infection in the general population. However, in individuals with specific genetic backgrounds, such as patients with epidermodysplasia verruciformis, or those with immune defects, such as organ transplant recipients, they are functionally involved in sunlight-induced skin cancer development, mainly keratinocyte carcinoma. Despite their well-established protumorigenic role, the cooperation between ß-HPV infection, impaired host immunosurveillance, and UVB exposure has never been formally shown in animal models. In this study, by crossing skin-specific HPV8-transgenic mice with Rag2-deficient mice, we have generated a preclinical mouse model, named Rag2‒/‒:K14-HPV8. These mice display an unhealthy skin phenotype and spontaneously develop papilloma-like lesions spreading to the entire skin much more rapidly compared with Rag2+/+:K14-HPV8 mice. Exposure to low doses of UVB radiation is sufficient to trigger severe skin inflammation in Rag2‒/‒:K14-HPV8 but not in Rag2+/+:K14-HPV8 mice. Their inflamed skin very much resembled that observed in cutaneous field cancerization in organ transplant recipients, showing high levels of UVB-damaged cells, enhanced production of proinflammatory cytokines, and mast cell recruitment to the dermis. Overall, this immunocompromised HPV8-transgenic mouse model shows that the coexistence of immune defects, ß-HPV, and UVB exposure promotes skin cancer development.

CD200 ectodomain shedding into the tumor microenvironment leads to NK cell dysfunction and apoptosis.

The basis of immune evasion, a hallmark of cancer, can differ even when cancers arise from one cell type such as in the human skin keratinocyte carcinomas: basal and squamous cell carcinoma. Here we showed that the basal cell carcinoma tumor-initiating cell surface protein CD200, through ectodomain shedding, was responsible for the near absence of NK cells within the basal cell carcinoma tumor microenvironment. In situ, CD200 underwent ectodomain shedding by metalloproteinases MMP3 and MMP11, which released biologically active soluble CD200 into the basal cell carcinoma microenvironment. CD200 bound its cognate receptor on NK cells to suppress MAPK pathway signaling that in turn blocked indirect (IFN-γ release) and direct cell killing. In addition, reduced ERK phosphorylation relinquished negative regulation of PPARγ-regulated gene transcription and led to membrane accumulation of the Fas/FADD death receptor and its ligand, FasL, which resulted in activation-induced apoptosis. Blocking CD200 inhibition of MAPK or PPARγ signaling restored NK cell survival and tumor cell killing, with relevance to many cancer types. Our results thus uncover a paradigm for CD200 as a potentially novel and targetable NK cell-specific immune checkpoint, which is responsible for NK cell-associated poor outcomes in many cancers.

Identification of Human Cutaneous Basal Cell Carcinoma Cancer Stem Cells.

The cancer stem cell model states that a subset of tumor cells, called "cancer stem cells," can initiate and propagate tumor growth through self-renewal, high proliferative capacity, and their ability to recreate tumor heterogeneity. In basal cell carcinoma (BCC), we have shown that tumor cells that express the cell surface protein CD200 fulfill the cancer stem cell hypothesis. CD200+ CD45- BCC cells represent 0.05-3.96% of all BCC cells and reside in small clusters at the tumor periphery. Using a novel, reproducible in vivo xenograft growth assay, we determined that tumor-initiating cell (TIC) frequencies are approximately 1 per 1.5 million unsorted BCC cells. The CD200+ CD45- BCC subpopulation recreated BCC tumor growth in vivo with typical histological architecture and expression of sonic hedgehog-regulated genes. Reproducible in vivo BCC growth was achieved with as few as 10,000 CD200+ CD45- cells, representing ~1500-fold enrichment. The methods used to identify and purify CD200+ CD45- BCC cells, as well as characterize gene expression, are described herein.

Identification of Human Cutaneous Squamous Cell Carcinoma Cancer Stem Cells.

Epithelia are under constant threat from environmental carcinogens and none more so than squamous epithelia, which form the outermost linings of our bodies. Hence malignancies of squamous epithelia are collectively the most common cancer type and with the highest mortality, despite a constant cell turnover and only relatively rare long-lived adult tissue stem cells. Genetic analysis from SCC whole genome sequencing reveals commonality in mutated genes, despite various etiological factors. Most SCC types have been shown to exhibit hierarchical growth, in which a high frequency of cancer stem cells is associated with poor prognosis. For human cutaneous SCC (cSCC), we have shown that cancer stem cells express CD133 and that this population can recreate tumor heterogeneity in a novel in vivo model. CD133+ cSCC cells is small subset of tumor cells (~1%) in the outer layer of cSCC that are highly enriched for tumor-initiating capacity (TIC) (~1/400) compared to unsorted cSCC cells (~1/106). Xenografts of CD133+ cSCC recreated the original cSCC tumor histology and organizational hierarchy, while CD133- cells did not. Only CD133+ cells demonstrated the capacity for self-renewal in serial transplantation studies. Hence, cSCC has the potential to be the ideal model in which to study SCC biology.

Metagenomic Discovery of 83 New Human Papillomavirus Types in Patients with Immunodeficiency.

Several immunodeficiencies are associated with high susceptibility to persistent and progressive human papillomavirus (HPV) infection leading to a wide range of cutaneous and mucosal lesions. However, the HPV types most commonly associated with such clinical manifestations in these patients have not been systematically defined. Here, we used virion enrichment, rolling circle amplification, and deep sequencing to identify circular DNA viruses present in skin swabs and/or wart biopsy samples from 48 patients with rare genetic immunodeficiencies, including patients with warts, hypogammaglobulinemia, infections, myelokathexis (WHIM) syndrome, or epidermodysplasia verruciformis (EV). Their profiles were compared with the profiles of swabs from 14 healthy adults and warts from 6 immunologically normal children. Individual patients were typically infected with multiple HPV types; up to 26 different types were isolated from a single patient (multiple anatomical sites, one time point). Among these, we identified the complete genomes of 83 previously unknown HPV types and 35 incomplete genomes representing possible additional new types. HPV types in the genus Gammapapillomavirus were common in WHIM patients, whereas EV patients mainly shed HPVs from the genus Betapapillomavirus. Preliminary evidence based on three WHIM patients treated with plerixafor, a leukocyte mobilizing agent, suggest that longer-term therapy may correlate with decreased HPV diversity and increased predominance of HPV types associated with childhood skin warts.IMPORTANCE Although some members of the viral family Papillomaviridae cause benign skin warts (papillomas), many human papillomavirus (HPV) infections are not associated with visible symptoms. For example, most healthy adults chronically shed Gammapapillomavirus (Gamma) virions from apparently healthy skin surfaces. To further explore the diversity of papillomaviruses, we performed viromic surveys on immunodeficient individuals suffering from florid skin warts. Our results nearly double the number of known Gamma HPV types and suggest that WHIM syndrome patients are uniquely susceptible to Gamma HPV-associated skin warts. Preliminary results suggest that treatment with the drug plerixafor may promote resolution of the unusual Gamma HPV skin warts observed in WHIM patients.

HPV-Induced Field Cancerisation: Transformation of Adult Tissue Stem Cell Into Cancer Stem Cell.

Field cancerisation was originally described as a basis for multiple head and neck squamous cell carcinoma (HNSCC) and is a pre-malignant phenomenon that is frequently attributable to oncogenic human papillomavirus (HPV) infection. Our work on ß-HPV-induced cutaneous squamous cell carcinomas identified a novel Lrig1+ hair follicle junctional zone keratinocyte stem cell population as the basis for field cancerisation. Herein, we describe the ability for HPV to infect adult tissue stem cells in order to establish persistent infection and induce their proliferation and displacement resulting in field cancerisation. By review of the HPV literature, we reveal how this mechanism is conserved as the basis of field cancerisation across many tissues. New insights have identified the capacity for HPV early region genes to dysregulate adult tissue stem cell self-renewal pathways ensuring that the expanded population preserve its stem cell characteristics beyond the stem cell niche. HPV-infected cells acquire additional transforming mutations that can give rise to intraepithelial neoplasia (IEN), from environmental factors such as sunlight or tobacco induced mutations in skin and oral cavity, respectively. With establishment of IEN, HPV viral replication is sacrificed with loss of the episome, and the tissue is predisposed to multiple cancer stem cell-driven carcinomas.

ß-HPV Infection Correlates with Early Stages of Carcinogenesis in Skin Tumors and Patient-Derived Xenografts from a Kidney Transplant Recipient Cohort.

Many malignancies that occur in high excess in kidney transplant recipients (KTRs) are due to viruses that thrive in the setting of immunosuppression. Keratinocyte carcinoma (KC), the most frequently occurring cancer type in KTR, has been associated with skin infection by human papillomavirus (HPV) from the beta genus. In this report, we extend our previous investigation aimed at identifying the presence of active ß-HPV infection in skin tumors from KTRs through detection of viral protein expression. Using a combination of antibodies raised against the E4 and L1 proteins of the ß-genotypes, we were able to visualize infection in five tumors [one keratoacanthoma (KA), three actinic keratoses (AKs), and one seborrheic keratoses (SKs)] that were all removed from two patients who had been both transplanted twice, had developed multiple KCs, and presented with a long history of immunosuppression (>30 years). These infected tissues displayed intraepidermal hyperplasia and increased expression of the ΔNp63 protein, which extended into the upper epithelial layers. In addition, using a xenograft model system in nude mice displaying a humanized stromal bed in the site of grafting, we successfully engrafted three AKs, two of which were derived from the aforementioned KTRs and displayed ß-HPV infection in the original tumor. Of note, one AK-derived xenograft, along with its ensuing lymph node metastasis, was diagnosed as squamous cell carcinoma (SCC). In the latter, both ß-HPV infection and ΔNp63 expression were no longer detectable. Although the overall success rate of engrafting was very low, the results of this study show for the first time that ß-HPV+ and ΔNp63+ intraepidermal hyperplasia can indeed progress to an aggressive SCC able to metastasize. Consistent with a series of reports attributing a causative role of ß-HPV at early stages of skin carcinogenesis through ΔNp63 induction and increased keratinocytes stemness, here we provide in vivo evidence that these events are also occurring in the affected skin of KTRs. Due to these ß-HPV-driven molecular pathways, the nascent tumor cell is able to acquire a high enough number of carcinogenic insults that its proliferation and survival will eventually become independent of viral gene expression.

Frequent detection of Merkel cell polyomavirus DNA in tissues from 10 consecutive autopsies.

Merkel cell polyomavirus (MCPyV) has been identified in samples of Merkel cell carcinoma (MCC), an aggressive skin cancer. Seroepidemiologic studies indicated a high frequency of MCPyV infection in humans, suggesting respiratory and faecal-oral routes, or transmission by skin contact. Since MCC is more frequent in immunocompromised patients, a reactivation of MCPyV latently infecting target cells has been proposed. However, neither definite ways of transmission nor specific target organs have been identified with certainty. Ten autopsies with an extensive organ sampling for a total of 121 specimens (tissue and blood samples) were collected. All tissue specimens were fixed in formalin and embedded in paraffin. Real-time PCR was performed to quantify the copy number of the large T antigen (LT) gene and the capsid VP1 gene of MCPyV. MCPyV LT and/or VP genes were detected in all of the collected specimens. A high prevalence of MCPyV was found in the blood (six cases) and lung (five cases); the brain was positive in three cases. The highest viral copy number was detected in blood from two autopsies (21 610 570.09 copies per 105 cells and 380 413.25 copies per 105 cells), whereas the viral copy number in the other organs was low. Our data confirm the high frequency of MCPyV infection in the general population, which seems to indicate that the respiratory tract is a possible route for viral transmission and viral persistence in the brain. The frequent detection of MCPyV DNA in blood suggests that circulating leukocytes could be one of the reservoirs of MCPyV, whereas the high viral copy number also seems to indicate the possibility of viral reactivation in immunocompetent adults.

HPV8 Field Cancerization in a Transgenic Mouse Model Is due to Lrig1+ Keratinocyte Stem Cell Expansion.

ß-Human papillomaviruses (HPVs) cause near ubiquitous latent skin infection within long-lived hair follicle (HF) keratinocyte stem cells. In patients with epidermodysplasia verruciformis, ß-HPV viral replication is associated with skin keratosis and cutaneous squamous cell carcinoma. To determine the role of HF keratinocyte stem cells in ß-HPV-induced skin carcinogenesis, we utilized a transgenic mouse model in which the keratin 14 promoter drives expression of the entire HPV8 early region (HPV8tg). HPV8tg mice developed thicker skin in comparison with wild-type littermates consistent with a hyperproliferative epidermis. HF keratinocyte proliferation was evident within the Lrig1+ keratinocyte stem cell population (69 vs. 55%, P < 0.01, n = 7), and not in the CD34+, LGR5+, and LGR6+ keratinocyte stem cell populations. This was associated with a 2.8-fold expansion in Lrig1+ keratinocytes and 3.8-fold increased colony-forming efficiency. Consistent with this, we observed nuclear p63 expression throughout this population and the HF infundibulum and adjoining interfollicular epidermis, associated with a switch from p63 transcriptional activation isoforms to ΔNp63 isoforms in HPV8tg skin. Epidermodysplasia verruciformis keratosis and in some cases actinic keratoses demonstrated similar histology associated with ß-HPV reactivation and nuclear p63 expression within the HF infundibulum and perifollicular epidermis. These findings would suggest that ß-HPV field cancerization arises from the HF junctional zone and predispose to squamous cell carcinoma.