Skin Tropism Research Articles

Skin metastasis of BRCA mutated prostate cancer: A case report and a brief review of literature.

Metastatic castration-resistant prostate cancer has a poor prognosis especially when harboring DNA damage repair gene mutations, nevertheless, in the case of pathogenic BRCA gene mutations, PARPi demonstrated a survival benefit and is a validated treatment. Nowadays, there is no data regarding unusual metastases after these drugs. Cutaneous metastases appear rarely in prostate cancer and were associated with a worse prognosis. Moreover, there are no consolidated data concerning skin tropism of prostate cancer cells, neither in the case of BRCA-associated cancers. Here, we report the case of a patient with a long history of BRCA1-mutated metastatic castration-resistant prostate cancer who developed a skin lesion on the scalp while on his fifth line of systemic therapy with olaparib. After a complete radical surgical excision, the pathology report showed prostate cancer localization. A diagnosis of skin metastasis from prostate cancer was reported. The patient then continued olaparib therapy; after 7 months from excision, he experienced further bone and biochemical progression but not cutaneous progression. A literature review of all reported cases of cutaneous metastasis in prostate cancer was conducted to shed light on the incidence, clinical presentation, diagnosis, treatment, and prognosis of this entity. We also reviewed published cases of skin metastasis in BRCA-associated cancers with an effort to correlate skin involvement with PARPi treatment, BRCAness status, and prognosis.

Skin tropism during Usutu virus and West Nile virus infection: an amplifying and immunological role.

Usutu virus (USUV) and West Nile virus (WNV) are closely related emerging arboviruses belonging to the Flavivirus genus and posing global public health concerns. Although human infection by these viruses is mainly asymptomatic, both have been associated with neurological disorders such as encephalitis and meningoencephalitis. Since USUV and WNV are transmitted through the bite of an infected mosquito, the skin represents the initial site of virus inoculation and provides the first line of host defense. Although some data on the early stages of WNV skin infection are available, very little is known about USUV. Herein, USUV-skin resident cell interactions were characterized. Using primary human keratinocytes and fibroblasts, an early replication of USUV during the first 24 hours was shown in both skin cells. In human skin explants, a high viral tropism for keratinocytes was observed. USUV infection of these models induced type I and III interferon responses associated with upregulated expression of various interferon-stimulated genes as well as pro-inflammatory cytokine and chemokine genes. Among the four USUV lineages studied, the Europe 2 strain replicated more efficiently in skin cells and induced a higher innate immune response. In vivo, USUV and WNV disseminated quickly from the inoculation site to distal cutaneous tissues. In addition, viral replication and persistence in skin cells were associated with an antiviral response. Taken together, these results provide a better understanding of the pathophysiology of the early steps of USUV infection and suggest that the skin constitutes a major amplifying organ for USUV and WNV infection.IMPORTANCEUsutu virus (USUV) and West Nile virus (WNV) are closely related emerging Flaviviruses transmitted through the bite of an infected mosquito. Since they are directly inoculated within the upper skin layers, the interactions between the virus and skin cells are critical in the pathophysiology of USUV and WNV infection. Here, during the early steps of infection, we showed that USUV can efficiently infect two human resident skin cell types at the inoculation site: the epidermal keratinocytes and the dermal fibroblasts, leading to the induction of an antiviral innate immune response. Moreover, following cutaneous inoculation, we demonstrated that both viruses can rapidly spread, replicate, and persist in all distal cutaneous tissues in mice, a phenomenon associated with a generalized skin inflammatory response. These results highlight the key amplifying and immunological role of the skin during USUV and WNV infection.

The Role of Diet in Children with Psoriasis: Emerging Evidence and Current Issues

Psoriasis is an immune-mediated inflammatory systemic disease with skin tropism and chronic relapsing course; it is associated with an increased cardiovascular risk and with many metabolic comorbidities, emerging during childhood in 22-33% of cases. Diet influences the presentation and the clinical course of inflammatory diseases, including psoriasis; in particular, it was shown that a Mediterranean, gluten-free, or low-calorie diet may positively affect disease control in adult patients with psoriasis and adequate pharmacological therapy. These three dietary regimens may play a role also in children with psoriasis. It has been demonstrated that pediatric psoriasis is associated with psychological stress, celiac disease, and obesity, which may be positively influenced by these dietary regimens, respectively. Therefore, the expertise of multiple health figures (gastroenterologists, nutritionists, pediatricians, dermatologists) is required to plan a tailor-made dietary strategy, ensuring good growth, through an adequate intake of essential micro- and macronutrients and, at the same time, impacting the pro-inflammatory biochemical profile and on the associated cardiovascular risk of psoriasis disease.

Prevalence of MCPyV, HPyV6, HPyV7 and TSPyV in Actinic Keratosis Biopsy Specimens.

To date, 14 human polyomaviruses (HPyVs) have been identified using high-throughput technologies. Among them, MCPyV, HPyV6, HPyV7 and TSPyV present a skin tropism, but a causal role in skin diseases has been established only for MCPyV as a causative agent of Merkel cell carcinoma (MCC) and TSPyV as an etiological agent of Trichodysplasia Spinulosa (TS). In the search for a possible role for cutaneous HPyVs in the development of skin malignant lesions, we investigated the prevalence of MCPyV, HPyV6, HPyV7 and TSPyV in actinic keratosis (AK), a premalignant skin lesion that has the potential to progress towards a squamous cell carcinoma (SCC). One skin lesion and one non-lesion skin from nine affected individuals were analyzed by qualitative PCR. MCPyV was detected in 9 out of 9 lesion biopsies and 6 out of 8 non-lesion biopsies. HPyV6 was detected only in healthy skin, while HPyV7 and TSPyV were not detected in any skin sample. These findings argue against a possible role of cutaneous HPyVs in AK. However, considering the small sample size analyzed, a definitive conclusion cannot be drawn. Longitudinal studies on large cohorts are warranted.

Leishmania infantum xenodiagnosis from vertically infected dogs reveals significant skin tropism.

Dogs are the primary reservoir for human visceral leishmaniasis due to Leishmania infantum. Phlebotomine sand flies maintain zoonotic transmission of parasites between dogs and humans. A subset of dogs is infected transplacentally during gestation, but at what stage of the clinical spectrum vertically infected dogs contribute to the infected sand fly pool is unknown. We examined infectiousness of dogs vertically infected with L. infantum from multiple clinical states to the vector Lutzomyia longipalpis using xenodiagnosis and found that vertically infected dogs were infectious to sand flies at differing rates. Dogs with mild to moderate disease showed significantly higher transmission to the vector than dogs with subclinical or severe disease. We documented a substantial parasite burden in the skin of vertically infected dogs by RT-qPCR, despite these dogs not having received intradermal parasites via sand flies. There was a highly significant correlation between skin parasite burden at the feeding site and sand fly parasite uptake. This suggests dogs with high skin parasite burden contribute the most to the infected sand fly pool. Although skin parasite load and parasitemia correlated with one another, the average parasite number detected in skin was significantly higher compared to blood in matched subjects. Thus, dermal resident parasites were infectious to sand flies from dogs without detectable parasitemia. Together, our data implicate skin parasite burden and earlier clinical status as stronger indicators of outward transmission potential than blood parasite burden. Our studies of a population of dogs without vector transmission highlights the need to consider canine vertical transmission in surveillance and prevention strategies.

P007 Identification and characterisation of intestine-derived circulating resident memory T cells (ex-Trm) in health and Inflammatory Bowel Disease

Abstract Background Tissue resident memory T cells (Trm) persist in peripheral tissues where they protect against pathogens but can also contribute to inflammatory disease. Recent work shows that Trm can re-enter the circulation and give rise to new effector T cell and Trm populations in secondary tissue sites. Such ‘ex -Trm’ derived from the skin co-express the residency marker CD103 with cutaneous leukocyte antigen (CLA), a marker associated with skin tropism. Many T cells in the human intestine are Trm but it is unknown whether these cells re-enter the circulation; the existence of gut-derived ex-Trm would have important implications for IBD treatment targeting the recruitment of circulating gut-homing cells. Here, we identify a population of blood cells that co-express CD103 and the gut-homing integrin a4b7 and determine how they are changed in IBD. Methods Peripheral blood mononuclear cells (PBMCs) were isolated from healthy volunteers and patients with active IBD (Crohn’s disease or ulcerative colitis). Cell surface staining and multi-colour flow cytometry were used to identify CD4+ and CD8+ subsets of antigen experienced (CD45RA-) conventional T cells (abTCR+) and determine expression of markers associated with tissue tropism and residency. Results Staining with antibodies to CD103 and b7 integrin were used to define CD103b7+a4b7+ putative gut ex-Trm based on the excess per cell expression of b7 resulting from its contribution to both integrins. A separate CD103b7+a4b7- population defined by 1:1 expression of CD103 and b7 contained CLA+ skin ex-Trm. Gut ex-Trm comprised 0.3% total circulating CD8+ T cells (range 0.02–1.4%), and 1.2% CD4+ T cells (range 0.3–3%). Gut and skin ex-Trm were phenotypically similar; both expressed the residency associated markers CD101 and CD9 but lacked expression of CD69. Gut ex-Trm were phenotypically distinct from both traditional CD103-a4b7+ gut tropic CD45RA- antigen-experienced T cells and naïve T cells; significantly more gut ex-Trm expressed CD101 and CD9 and fewer expressed CD27. The proportion of gut ex-Trm did not differ between heath and IBD. However, the ratio of gut:skin ex Trm was significantly reduced in active Crohn’s disease but not ulcerative colitis indicating a selective reduction in the population derived from the intestine. Conclusion A putative population of gut-derived ex-Trm can be identified in the blood of healthy controls and IBD patients. This population has a distinctive phenotype similar to that of previously described skin-derived ex-Trm. Circulating ex-Trm could link discreet areas of intestinal inflammation in Crohn’s disease and there is a selective loss of the gut ex-Trm population from the blood of these patients. The role of ex-Trm in IBD merits further study.

Murine model of colonization with fungal pathogen Candida auris to explore skin tropism, host risk factors and therapeutic strategies

Candida auris is an emerging multi-drug-resistant human fungal pathogen. C.auris skin colonization results in environmental shedding, which underlies hospital transmissions, and predisposes patients to subsequent infections. We developed a murine skin topical exposure model for C.auris to dissect risk factors for colonization and to test interventions that might protect patients. We demonstrate that C.auris establishes long-term residence within the skin tissue compartment, which would elude clinical surveillance. The four clades of C.auris, with geographically distinct origins, differ in their abilities to colonize murine skin, mirroring epidemiologic findings. The IL-17 receptor signaling and specific arms of immunity protect mice from long-term C.auris skin colonization. We further determine that commonly used chlorhexidine antiseptic serves as a protective and decolonizing agent against C.auris. This translational model facilitates an integrated approach to develop strategies to combat the unfolding global outbreaks of C.auris and other skin-associated microbial pathogens.

The Use of Single Cell Mass Cytometry to Define the Molecular Mechanisms of Varicella-Zoster Virus Lymphotropism.

Unraveling the heterogeneity in biological systems provides the key to understanding of the fundamental dynamics that regulate host pathogen relationships at the single cell level. While most studies have determined virus-host cell interactions using cultured cells in bulk, recent advances in deep protein profiling from single cells enable the understanding of the dynamic response equilibrium of single cells even within the same cell types. Mass cytometry allows the simultaneous detection of multiple proteins in single cells, which helps to evaluate alterations in multiple signaling networks that work in tandem in deciding the response of a cell to the presence of a pathogen or other stimulus. In applying this technique to studying varicella zoster virus (VZV), it was possible to better understand the molecular basis for lymphotropism of the virus and how virus-induced effects on T cells promoted skin tropism. While the ability of VZV to manifest itself in the skin is well established, how the virus is transported to the skin and causes the characteristic VZV skin lesions was not well elucidated. Through mass cytometry analysis of VZV-infected tonsil T cells, we were able to observe that VZV unleashes a “remodeling” program in the infected T cells that not only makes these T cells more skin tropic but also at the same time induces changes that make these T cells unlikely to respond to immune stimulation during the journey to the skin.

Inflammation following trypanosome infection and persistence in the skin.

Human African trypanosomes rely for their transmission on tsetse flies (Glossina sp.) that inoculate parasites into the skin during blood feeding. The absence of a protective vaccine, limited knowledge about the infection immunology, and the existence of asymptomatic carriers sustaining transmission are major outstanding challenges towards elimination. All these relate to the skin where (i) parasites persist and transmit to tsetse flies and (ii) a successful vaccination strategy should ideally be effective. Host immune processes and parasite strategies that underlie early infection and skin tropism are essential aspects to comprehend the transmission-success of trypanosomes and the failure in vaccine development. Recent insights into the early infection establishment may pave the way to novel strategies aimed at blocking transmission.

Reconstruction of a long defect of the median nerve with a free nerve conduit flap

Upper limb nerve damage is a common condition, and evidence suggests that functional recovery may be limited following peripheral nerve repair in cases of delayed reconstruction or reconstruction of long nerve defects. A 26-year-old man presented with traumatic injury from a wide, blunt wound of the right forearm caused by broken glass, with soft tissue loss, complete transection of the radial and ulnar arteries, and a large median nerve gap. The patient underwent debridement and subsequent surgery with a microsurgical free radial fasciocutaneous flap to provide a direct blood supply to the hand; the cephalic vein within the flap was employed as a venous vascularized chamber to wrap the sural nerve graft and to repair the wide gap (14 cm) in the median nerve. During the postoperative period, the patient followed an intensive rehabilitation program and was monitored for functional performance over 5 years of follow-up. Our assessment demonstrated skin tropism and sufficient muscle power to act against strong resistance (M5) in the muscles previously affected by paralysis, as well as a good localization of stimuli in the median nerve region and an imperfect recovery of two-point discrimination (S3+). We propose a novel and efficient procedure to repair >10-cm peripheral nerve gap injuries related to upper limb trauma.

Blastic Plasmacytoid Dendritic Cell Neoplasia: A Single Center Experience

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare malignancy with skin tropism. The entity was recently defined and the diagnosis is generally made by skin biopsies. It is necessary to apply appropriate immunohistochemistry to recognize this rare entity. There is no consensus on therapy and the survival rates are low. The aim of this study is to describe the clinical and histopathological features of BPDCN. We retrospectively reviewed 8 BPDCN cases of the Cerrahpaşa Medical Faculty diagnosed between 2005 and 2019. We documented the clinical findings, histopathologic diagnoses, and outcomes. The mean age of the patients was 58.7 years (range=11-86 years), and 7 patients were male. The patients presented with erythematous or purple papules, plaques, and papulonodular or nodular cutaneous lesions. Two had lymphadenomegaly at presentation. In microscopic evaluations, tumor cells infiltrated the entire dermis with a clear-cut subepidermal Grenz zone in all cases. CD4, CD56, and CD123 were the most frequently expressed immunohistochemical markers. The median follow-up of 7 cases was 14 months, ranging from 6 to 48 months. Three patients died of the disease, while 4 patients were still alive. Out of 7 patients, 5 received chemotherapy. We found that the outcomes of some patients were different from others but we did not link any distinct clinical or histopathological characteristics to these different outcomes.

Treatment of patients with primary cutaneous lymphomas – real-life data

Background. Primary cutaneous lymphomas (PCL) comprise a heterogeneous group of neoplasms of mature lymphocytes with skin tropism. Although, by definition, these lymphomas are restricted to the skin at the time of diagnosis, during the course of the disease it may involve also lymph nodes and visceral organs. A close cooperation between a dermatologist and oncologist is required to ensure proper treatment. We present in a real-life data on treatment of patients with PCL between dermatology and oncology department. Material and methods. 104 patients were registered in a joined database of Oncology Department of Oncology Centre in Bydgoszcz and Dermatology Department of Medical University in Torun between 2007 and 2017. Due to different clinical and prognostic features data from MF/SS (44 patients), non-MF/SS CTCLs and CBCLs were presented separately. Results. Median overall survival for patients with MF/SS was 76.7 months. Median follow-up time was 5 years.

Tissue Tropism in Streptococcal Infection: Wild-Type M1T1 Group A Streptococcus Is Efficiently Cleared by Neutrophils Using an NADPH Oxidase-Dependent Mechanism in the Lung but Not in the Skin.

Group A Streptococcus (GAS) commonly causes pharyngitis and skin infections. Little is known why streptococcal pharyngitis usually does not lead to pneumonia and why the skin is a favorite niche for GAS. To partially address these questions, the effectiveness of neutrophils in clearing wild-type (wt) M1T1 GAS strain MGAS2221 from the lung and from the skin was examined in murine models of intratracheal pneumonia and subcutaneous infection. Ninety-nine point seven percent of the MGAS2221 inoculum was cleared from the lungs of C57BL/6J mice at 24 h after inoculation, while there was no MGAS2221 clearance from skin infection sites. The bronchial termini had robust neutrophil infiltration, and depletion of neutrophils abolished MGAS2221 clearance from the lung. Phagocyte NADPH oxidase but not myeloperoxidase was required for MGAS2221 clearance. Thus, wt M1T1 GAS can be cleared by neutrophils using an NADPH oxidase-dependent mechanism in the lung. MGAS2221 induced robust neutrophil infiltration at the edge of skin infection sites and throughout infection sites at 24 h and 48 h after inoculation, respectively. Neutrophils within MGAS2221 infection sites had no nuclear staining. Skin infection sites of streptolysin S-deficient MGAS2221 ΔsagA were full of neutrophils with nuclear staining, whereas MGAS2221 ΔsagA infection was not cleared. Gp91phox knockout (KO) and control mice had similar GAS numbers at skin infection sites and similar abilities to select SpeB activity-negative (SpeBA-) variants. These results indicate that phagocyte NADPH oxidase-mediated GAS killing is compromised in the skin. Our findings support a model for GAS skin tropism in which GAS generates an anoxic niche to evade phagocyte NADPH oxidase-mediated clearance.

Autologous micro-fragmented adipose tissue for the treatment of diabetic foot minor amputations: a randomized controlled single-center clinical trial (MiFrAADiF)

BackgroundThe diabetic foot ulcer (DFU) is one of the most prevalent complications of diabetes mellitus and often develops severe effects that can lead to amputation. A non-healing “minor” amputation often precedes a major amputation resulting in a negative impact on the function and quality of life of the patients. Stem cell-based therapies have emerged as a promising option to improve healing, and the adipose tissue is an abundant and easy to access source. The injection of autologous micro-fragmented adipose tissue at the amputation stump of a diabetic population undergoing a lower limb minor amputation was evaluated and compared with the standard care.MethodsIn this randomized controlled trial with two arms (parallel assignment) and no masking, 114 patients undergoing a lower limb minor amputation were randomized to standard of care or to micro-fragmented adipose tissue injection prepared using a minimal manipulation technique (Lipogems®) in a closed system. Clinical outcomes were determined monthly up to 6 months. Primary endpoint of the study was the evaluation of the healing rate and time after the minor amputation. Secondary endpoints included the assessment of safety, feasibility, technical success, relapse rate, skin tropism, and intensity of pain.ResultsAt 6 months, 80% of the micro-fragmented adipose tissue-treated feet healed and 20% failed as compared with the control group where 46% healed and 54% failed (p = 0.0064). No treatment-related adverse events nor relapses were documented, and technical success was achieved in all cases. The skin tropism was improved in the treatment group, and the pain scale did not differ between the two groups.ConclusionThe results of this randomized controlled trial suggest that the local injection of autologous micro-fragmented adipose tissue is a safe and valid therapeutic option able to improve healing rate following minor amputations of irreversible DFU. The technique overcomes several stem cell therapy-related criticisms and its potential in wound care should be better evaluated and the therapeutic indications could be expanded.Trial registrationClinicalTrials.gov number: NCT03276312. Date of registration: September 8, 2017 (retrospectively registered).

The C-terminus of varicella-zoster virus glycoprotein M contains trafficking motifs that mediate skin virulence in the SCID-human model of VZV pathogenesis

Knowledge about the function of varicella-zoster virus glycoprotein M is limited; the requirement of gM for skin and neural tropism are unknown. VZV gM contains two predicted YXXΦ trafficking motifs and a dileucine motif in the carboxyl-terminus. We constructed a recombinant VZV with gM truncated from the first YXXΦ and five additional viruses with YXXΦ tyrosine substitutions, alone and in combination with dileucine substitution. All recombinant viruses grew to high titer but mutation of the membrane-proximal YXXΦ motif reduced plaque size in cultured cells and altered gM localization. C-terminus truncation had a pronounced effect on virion morphogenesis and plaque size, but not on overall replication kinetics in vitro. Mutation of gM trafficking motifs and truncation attenuated replication in human skin xenografts in vivo; gM truncation did not alter neurotropism. Our results demonstrate that the gM C-terminus is dispensable for virus replication in cultured cells but is important for skin pathogenesis.

IL-2 Enhances Gut Homing Potential of Human Naive Regulatory T Cells Early in Life.

Recent evidence suggests early environmental factors are important for gut immune tolerance. Although the role of regulatory T (Treg) cells for gut immune homeostasis is well established, the development and tissue homing characteristics of Treg cells in children have not been studied in detail. In this article, we studied the development and homing characteristics of human peripheral blood Treg cell subsets and potential mechanisms inducing homing molecule expression in healthy children. We found contrasting patterns of circulating Treg cell gut and skin tropism, with abundant β7 integrin+ Treg cells at birth and increasing cutaneous lymphocyte Ag (CLA+) Treg cells later in life. β7 integrin+ Treg cells were predominantly naive, suggesting acquisition of Treg cell gut tropism early in development. In vitro, IL-7 enhanced gut homing but reduced skin homing molecule expression in conventional T cells, whereas IL-2 induced a similar effect only in Treg cells. This effect was more pronounced in cord compared with adult blood. Our results suggest that early in life, naive Treg cells may be driven for gut tropism by their increased sensitivity to IL-2-induced β7 integrin upregulation, implicating a potential role of IL-2 in gut immune tolerance during this critical period of development.

Cellular Stress Response to Varicella-Zoster Virus Infection of Human Skin Includes Highly Elevated Interleukin-6 Expression.

The infectious cycle of varicella-zoster virus (VZV) after reactivation from the dorsal root ganglia includes replication and assembly of complete enveloped virions in the human skin to cause the characteristic herpes zoster (shingles). To pursue studies of innate immunity to VZV infection, we have adapted a fetal skin organ culture model to a human neonatal foreskin explant model. Abundant expression of VZV IE62, gE, and gC was visualized by confocal microscopy while numerous enveloped virions were observed by electron microscopy in infected skin organ cultures. Microarray experiments demonstrated that the patterns of upregulated transcripts differed between VZV-infected cells and VZV-infected skin explants. One result stood out, namely a >30-fold elevated interleukin (IL)-6 level in the infected skin explant that was not present in the infected monolayer culture. The IL-6 results in the polyermase chain reaction (PCR) assay were reproduced by quantitative PCR testing with newly designed primers. To determine if increased transcription was accompanied by increased IL-6 expression, we quantitated the levels of IL-6 protein in the explant media at increasing intervals after infection. We found a statistically significant increase in IL-6 protein levels secreted into the media from VZV-infected skin explants as compared with mock-infected explants. The cellular stress response to VZV infection in neonatal skin explants included highly elevated levels of IL-6 transcription and expression. This skin organ model could be adapted to other viruses with a skin tropism, such as herpes simplex virus.

A point mutation in AgrC determines cytotoxic or colonizing properties associated with phenotypic variants of ST22 MRSA strains.

Methicillin-resistant Staphylococcus aureus (MRSA) is a major cause of skin and soft tissue infections. One of the highly successful and rapidly disseminating clones is MRSA ST22 commonly associated with skin tropism. Here we show that a naturally occurring single amino acid substitution (tyrosine to cysteine) at position 223 of AgrC determines starkly different ST22 S. aureus virulence phenotypes, e.g. cytotoxic or colonizing, as evident in both in vitro and in vivo skin infections. Y223C amino acid substitution destabilizes AgrC-AgrA interaction leading to a colonizing phenotype characterized by upregulation of bacterial surface proteins. The colonizing phenotype strains cause less severe skin tissue damage, show decreased susceptibility towards the antimicrobial LL-37 and induce autophagy. In contrast, cytotoxic strains with tyrosine at position 223 of AgrC cause infections characterized by inflammasome activation and severe skin tissue pathology. Taken together, the study demonstrates how a single amino acid substitution in the histidine kinase receptor AgrC of ST22 strains determines virulence properties and infection outcome.

Analysis of the functional consequences of targeted exon deletion in COL7A1 reveals prospects for dystrophic epidermolysis bullosa therapy.

Genetically evoked deficiency of collagen VII causes dystrophic epidermolysis bullosa (DEB)-a debilitating disease characterized by chronic skin fragility and progressive fibrosis. Removal of exons carrying frame-disrupting mutations can reinstate protein expression in genetic diseases. The therapeutic potential of this approach is critically dependent on gene, protein, and disease intrinsic factors. Naturally occurring exon skipping in COL7A1, translating collagen VII, suggests that skipping of exons containing disease-causing mutations may be feasible for the treatment of DEB. However, despite a primarily in-frame arrangement of exons in the COL7A1 gene, no general conclusion of the aptitude of exon skipping for DEB can be drawn, since regulation of collagen VII functionality is complex involving folding, intra- and intermolecular interactions. To directly address this, we deleted two conceptually important exons located at both ends of COL7A1, exon 13, containing recurrent mutations, and exon 105, predicted to impact folding. The resulting recombinantly expressed proteins showed conserved functionality in biochemical and in vitro assays. Injected into DEB mice, the proteins promoted skin stability. By demonstrating functionality of internally deleted collagen VII variants, our study provides support of targeted exon deletion or skipping as a potential therapy to treat a large number of individuals with DEB.

HPyV6, HPyV7 and TSPyV DNA sequences detection in skin disease patients and healthy subjects.

The discovery, from 2007, of eight new human polyomaviruses (HPyVs) has revived interest in the Polyomaviridae family and their association with human diseases and cancer. In particular, HPyV6 and HPyV7 were discovered in skin swabs of healthy donors and TSPyV was discovered in a heart transplant recipient affected by virus-associated Trichodysplasia Spinulosa (TS), a rare skin disease, exclusively found in immunocompromised patients. The presence of HPyV6, HPyV7 and TSPyV DNA in skin biopsies from patients affected by different skin diseases (cancers and inflammatory disorders) has been evaluated to confirm their skin tropism and the possible pathological association. DNA extracted was amplified with HPyV6, HPyV7 and TSPyV specific PCR real time on Taqman platform with standard profile. HPyV7 and TSPyV sequences were not found in any skin specimen analysed. HPyV6, on the other hand, was detected in 30% of samples from healthy subjects vs. 14.3% of skin cancer patients and 2.9% of inflammatory disorders. HPyV6 sequences have been detected in primary cutaneous T-cell lymphoma (CTCL) patients (in 18.6% out of Mycosis Fungoides (MF) patients and in 16.7% out of CTCL not MF/SS(Sèzary syndrome) but have not been detected in primary cutaneous B-cell lymphoma (CBCL) patients. Our preliminary data suggest that these three novel human polyomaviruses seem not to play a significant role neither in the pathogenesis of cutaneous malignancies nor in that of inflammatory disorders but, according to literature, can inhabit the skin. On the basis of our data regarding the HPyV6 DNA presence with decreasing percentages in healthy subjects, skin cancer and inflammatory disorders patients, it could be an intriguing matter to study if the activated innate immune response in inflammatory disorders can suppress the virus. Further investigations are needed to better understand their relationship with the human host and its innate immune system.