John T Seykora

University of Pennsylvania, Philadelphia, Pennsylvania, United States

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Publications (67)298.27 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Colorimetric staining techniques such as immunohistochemistry (IHC), immunofluorescence (IF) and histochemistry (HC) provide useful information regarding the localization and relative amount of a molecule/substance in skin. We have developed a novel, straightforward method to assess colorimetric staining by combining features from two open-source software programs. As a proof of principle, we demonstrate the utility of this approach by analyzing changes in skin melanin deposition during the radiation-induced tanning response of Yucatan mini-pigs. This method includes a visualization step to validate the accuracy of color selection before quantitation to ensure accuracy. The data show that this method is robust and will provide a means to obtain accurate comparative analyses of staining in IHC/IF/HC samples. This article is protected by copyright. All rights reserved.
    Experimental dermatology. 11/2014;
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    ABSTRACT: A functional epidermal skin barrier requires the formation of a cornified envelope from terminally differentiating keratinocytes. During this process, multiple genetic and environmental signals coordinately regulate protein expression and tissue differentiation. Here we describe a critical role for hypoxia-inducible factors (HIFs) in the regulation of filaggrin expression and skin barrier formation. Similar to other mammalian tissues, fetal epidermis in mice is normally O2-deprived. Simultaneous deletion of Hif1a and Hif2a in murine epidermis revealed defects in keratinocyte terminal differentiation and epidermal barrier formation. Mice lacking Hif1a and Hif2a in the epidermis exhibited dry flaky skin, impaired permeability barrier, and enhanced sensitivity to cutaneous allergens. These defects were correlated with stratum granulosum attenuation and reduced filaggrin expression. Hypoxic treatment of primary keratinocytes induced filaggrin (Flg) gene expression in a HIF1α- and HIF2α-dependent manner, suggesting that one mechanism by which Hif1a and Hif2a loss causes epidermal barrier defects in mice lies in Flg dysregulation. Therefore, low O2 tension is an essential component of the epidermal environment that contributes to skin development and function.Journal of Investigative Dermatology accepted article preview online, 07 July 2014; doi:10.1038/jid.2014.283.
    The Journal of investigative dermatology. 07/2014;
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    Adam I Rubin, John T Seykora
    Journal of Cutaneous Pathology 10/2013; · 1.77 Impact Factor
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    ABSTRACT: : Microcystic adnexal carcinoma (MAC) is an uncommon, locally aggressive, malignant cutaneous tumor with pilar and eccrine differentiation. Mohs micrographic surgery is the treatment of choice for this condition, but specific histological findings can complicate MAC removal and leave doubt as to whether the tumor has been completely removed. Here we describe the clinical and pathological characteristics of a case in which a patient with an MAC underwent multiple reexcisions because of the presence of benign subclinical syringomatous proliferations adjacent to the primary lesion. Our case raises awareness of syringomatous proliferation, a benign process histologically similar but behaviorally distinct from a primary MAC. This experience highlights the importance of continued communication between dermatopathologists and dermatologic surgeons in providing quality patient care.
    The American Journal of dermatopathology 09/2013; · 1.30 Impact Factor
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    ABSTRACT: The skin is colonized by a plethora of microbes that include commensals and potential pathogens, but it is currently unknown how cutaneous host immune mechanisms influence the composition, diversity, and quantity of the skin microbiota. Here we reveal an interactive role for complement in cutaneous host-microbiome interactions. Inhibiting signaling of the complement component C5a receptor (C5aR) altered the composition and diversity of the skin microbiota as revealed by deep sequencing of the bacterial 16S rRNA gene. In parallel, we demonstrate that C5aR inhibition results in down-regulation of genes encoding cutaneous antimicrobial peptides, pattern recognition receptors, and proinflammatory mediators. Immunohistochemistry of inflammatory cell infiltrates in the skin showed reduced numbers of macrophages and lymphocytes with C5aR inhibition. Further, comparing cutaneous gene expression in germ-free mice vs. conventionally raised mice suggests that the commensal microbiota regulates expression of complement genes in the skin. These findings demonstrate a component of host immunity that impacts colonization of the skin by the commensal microbiota and vice versa, a critical step toward understanding host-microbe immune mutualism of the skin and its implications for health and disease. Additionally, we reveal a role for complement in homeostatic host-microbiome interactions of the skin.
    Proceedings of the National Academy of Sciences 08/2013; · 9.81 Impact Factor
  • JAMA dermatology (Chicago, Ill.). 05/2013; 149(5):637-9.
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    ABSTRACT: We determined the feasibility of using an anti-desmoglein (Dsg) monoclonal antibody, Px44, to deliver a biologically active protein to keratinocytes. Recombinantly produced Px44-green fluorescent protein (GFP) injected into mice and skin organ culture delivered GFP to the cell surface of keratinocytes. We replaced GFP with tumor necrosis factor -related apoptosis-inducing ligand (TRAIL) to produce Px44TRAIL. We chose TRAIL as a biologic model because it inhibits activated lymphocytes and causes apoptosis of hyperproliferative keratinocytes, features of various skin diseases. Px44TRAIL formed a trimer, the biologically active form of TRAIL. Standard assays of TRAIL activity showed that Px44TRAIL caused apoptosis of Jurkat cells and inhibited interferon-γ production by activated CD4+ T cells. Enzyme-linked immunoassay with Px44TRAIL showed delivery of TRAIL to Dsg. Immunofluorescence with Px44TRAIL incubated on skin sections and cultured keratinocytes or injected into mouse skin, human organ culture or human xenografts detected TRAIL on keratinocytes. Px44TRAIL caused apoptosis of hyperproliferative, but not differentiating, cultured keratinocytes through binding to Dsg3. Foldon, a small trimerization domain, cloned into Px44TRAIL maintained its stability and biological activity at 37(o) for at least 48 hr. These data suggest that such targeted therapy is feasible and may be useful for hyperproliferative and inflamed skin diseases.Journal of Investigative Dermatology accepted article preview online, 25 February 2013; doi:10.1038/jid.2013.85.
    Journal of Investigative Dermatology 02/2013; · 6.19 Impact Factor
  • Michael D Gober, Hasan M Bashir, John T Seykora
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    ABSTRACT: The American Cancer Society estimates that skin cancer is the most prevalent of all cancers with over 2 million cases of nonmelanoma skin cancer each year and 75,000 melanoma cases in 2012. Representative animal cancer models are important for understanding the underlying molecular pathogenesis of these cancers and the development of novel targeted anticancer therapeutics. In this review, we will discuss some of the important animal models that have been useful to identify important pathways involved in basal cell carcinoma, squamous cell carcinoma, and melanoma.
    CANCER AND METASTASIS REVIEW 11/2012; · 9.35 Impact Factor
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    ABSTRACT: BACKGROUND: Vemurafenib, a novel selective small molecule inhibitor of BRAF, has recently been shown to be effective in the treatment of melanomas harboring the BRAF V600E mutation. Similar to the broad-spectrum RAF inhibitor sorafenib, vemurafenib induces development of squamous cell carcinomas and keratoacanthomas as a side effect of therapy. OBJECTIVE: We sought to detail additional cutaneous adverse effects of vemurafenib and a similar BRAF inhibitor, dabrafenib. METHODS: We evaluated the clinical and histologic feature of skin side effects developing on vemurafenib or dabrafenib therapy in 14 patients. RESULTS: Eight patients developed one or more squamous cell carcinomas, and 11 patients formed benign verrucous keratoses. Eight patients developed single lesions and/or widespread eruptions with histopathologic findings of acantholytic dyskeratosis, consistent with warty dyskeratomas and Darier- or Grover-like rashes, respectively. One patient developed palmoplantar hyperkeratosis, and darkening of existing nevi and new nevi within 2 months of starting vemurafenib. Side effects presented as early as 1 week after beginning therapy, with a mean time of onset of 12.6 weeks in our cohort. LIMITATIONS: This study was limited by the small number of cases, all from a single institution. CONCLUSION: Selective BRAF inhibitor therapy is associated with the development of malignant and benign growths, including keratoacanthoma-like squamous cell carcinomas, warty dyskeratomas, and verrucous keratoses, along with widespread eruptions with histologic features of acantholytic dyskeratosis. Given the potential for malignant lesions to develop on treatment, awareness of potential adverse effects of these agents is necessary, and a low threshold for biopsy of new growths is recommended.
    Journal of the American Academy of Dermatology 05/2012; · 4.91 Impact Factor
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    ABSTRACT: Equestrian perniosis (EP) is a rare condition in which patients develop tender burning nodular plaques on their bilateral thighs after riding in the cold. These lesions tend to resolve rapidly with minimal exposure to cold, and wearing loose, layered warm clothing. Unlike acral perniosis, EP has no known systemic disease associations, although 2 reported cases did have elevated cold agglutinins. The histology of this disease is similar to perniosis; however, EP is distinct in that the perivascular lymphocytic infiltrate prominently involves the fat. In this case report, we discuss the clinical and histological findings in 2 cases of EP, including the first documented in a man.
    The American Journal of dermatopathology 04/2012; · 1.30 Impact Factor
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    ABSTRACT: MicroRNAs (miRNAs) regulate the expression of many mammalian genes and play key roles in embryonic hair follicle development; however, little is known of their functions in postnatal hair growth. We compared the effects of deleting the essential miRNA biogenesis enzymes Drosha and Dicer in mouse skin epithelial cells at successive postnatal time points. Deletion of either Drosha or Dicer during an established growth phase (anagen) caused failure of hair follicles to enter a normal catagen regression phase, eventual follicular degradation and stem cell loss. Deletion of Drosha or Dicer in resting phase follicles did not affect follicular structure or epithelial stem cell maintenance, and stimulation of anagen by hair plucking caused follicular proliferation and formation of a primitive transient amplifying matrix population. However, mutant matrix cells exhibited apoptosis and DNA damage and hair follicles rapidly degraded. Hair follicle defects at early time points post-deletion occurred in the absence of inflammation, but a dermal inflammatory response and hyperproliferation of interfollicular epidermis accompanied subsequent hair follicle degradation. These data reveal multiple functions for Drosha and Dicer in suppressing DNA damage in rapidly proliferating follicular matrix cells, facilitating catagen and maintaining follicular structures and their associated stem cells. Although Drosha and Dicer each possess independent non-miRNA-related functions, the similarity in phenotypes of the inducible epidermal Drosha and Dicer mutants indicates that these defects result primarily from failure of miRNA processing. Consistent with this, Dicer deletion resulted in the upregulation of multiple direct targets of the highly expressed epithelial miRNA miR-205.
    Development 04/2012; 139(8):1405-16. · 6.60 Impact Factor
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    ABSTRACT: Cutaneous squamous cell carcinoma (cSCC) is the second most common human cancer with over 250,000 new cases annually in the US and is second in incidence only to basal cell carcinoma. cSCC typically manifests as a spectrum of progressively advanced malignancies, ranging from a precursor actinic keratosis (AK) to squamous cell carcinoma (SCC) in situ (SCCIS), invasive cSCC, and finally metastatic SCC. In this Review we discuss clinical and molecular parameters used to define this range of cutaneous neoplasia and integrate these with the multiple experimental approaches used to study this disease. Insights gained from modeling cSCCs have suggested innovative therapeutic targets for treating these lesions.
    The Journal of clinical investigation 02/2012; 122(2):464-72. · 15.39 Impact Factor
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    ABSTRACT: Viral-associated trichodysplasia of immunosuppression is a rare cutaneous eruption that is characterized by follicularly based shiny papules and alopecia with characteristic histopathologic findings of abnormally anagen follicules with excessive inner root sheath differentiation. Prior reports have described the histopathologic characteristics on vertical sections; however, to our knowledge, immunohistochemical analysis of polyomavirus proteins has not been previously performed. We discuss the thorough diagnostic evaluation and therapy of an unusual case of viral-associated trichodysplasia due to a newly described human polyomavirus that occurred in a patient with posttreatment chronic lymphocytic leukemia and an abnormal white blood cell count. Unique to our study is the immunohistochemical staining for the polyomavirus middle T antigen, which demonstrated positive staining of cellular inclusions within keratinocytes that compose the inner root sheath. Further evaluation with scanning electron microscopy and polymerase chain reaction analysis of viral DNA confirmed the presence of the virus. Treatment with topical cidofovir resulted in dramatic clinical improvement and hair regrowth. Several tools, including immunohistochemical staining for the polyomavirus middle T antigen, can be used to identify the pathogenic virus associated with viral-associated trichodysplasia. This case highlights the utility of multiple diagnostic modalities and a robust response to a topical therapeutic agent, cidofovir.
    Archives of dermatology 02/2012; 148(2):219-23. · 4.76 Impact Factor
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    ABSTRACT: In a solar particle event (SPE), an unshielded astronaut would receive proton radiation with an energy profile that produces a highly inhomogeneous dose distribution (skin receiving a greater dose than internal organs). The novel concept of using megavoltage electron-beam radiation to more accurately reproduce both the total dose and the dose distribution of SPE protons and make meaningful RBE comparisons between protons and conventional radiation has been described previously. Here, Yucatan minipigs were used to determine the effects of a superficial, SPE-like proton dose distribution using megavoltage electrons. In these experiments, dose-dependent increases in skin pigmentation, ulceration, keratinocyte necrosis and pigment incontinence were observed. Five of 18 animals (one each exposed to 7.5 Gy and 12.5 Gy radiation and three exposed to 25 Gy radiation) developed symptomatic, radiation-associated pneumonopathy approximately 90 days postirradiation. The three animals from the highest dose group showed evidence of mycoplasmal pneumonia along with radiation pneumonitis. Moreover, delayed-type hypersensitivity was found to be altered, suggesting that superficial irradiation of the skin with ionizing radiation might cause immune dysfunction or dysregulation. In conclusion, using total doses, patterns of dose distribution, and dose rates that are compatible with potential astronaut exposure to SPE radiation, animals experienced significant toxicities that were qualitatively different from toxicities previously reported in pigs for homogeneously delivered radiation at similar doses.
    Radiation Research 08/2011; 176(5):649-59. · 2.70 Impact Factor
  • Journal of Cutaneous Pathology 08/2011; 38(8):603-6. · 1.77 Impact Factor
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    ABSTRACT: The Hippo pathway regulates contact inhibition of cell proliferation and, ultimately, organ size in diverse multicellular organisms. Inactivation of the Hippo pathway promotes nuclear localization of the transcriptional coactivator Yap1, a Hippo pathway effector, and can cause cancer. Here, we show that deletion of αE (α epithelial) catenin in the hair follicle stem cell compartment resulted in the development of skin squamous cell carcinoma in mice. Tumor formation was accelerated by simultaneous deletion of αE-catenin and the tumor suppressor-encoding gene p53. A small interfering RNA screen revealed a functional connection between αE-catenin and Yap1. By interacting with Yap1, αE-catenin promoted its cytoplasmic localization, and Yap1 showed constitutive nuclear localization in αE-catenin-null cells. We also found an inverse correlation between αE-catenin abundance and Yap1 activation in human squamous cell carcinoma tumors. These findings identify αE-catenin as a tumor suppressor that inhibits Yap1 activity and sequesters it in the cytoplasm.
    Science Signaling 01/2011; 4(174):ra33. · 7.65 Impact Factor
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    ABSTRACT: Cicatricial forms of alopecia, including lichen planopilaris (LPP) and discoid lupus erythematosus (DLE), may present with overlapping clinical features. In such cases, histopathological examination may provide key information for resolving the differential diagnosis. Optimally, microscopical analysis for alopecia requires both vertical and horizontal sections, and this may necessitate multiple samples. Here, we present what we term the "HoVert" technique, which produces horizontal and vertical sections from a single biopsy. We hypothesize that the HoVert technique should be useful for differentiating DLE from LPP. A formalin-fixed 4 mm punch scalp biopsy is transected approximately 1 mm below the skin surface to create an epidermal disc and a lower portion. The epidermal disc is bisected and embedded in conventional fashion to obtain vertical sections. The lower portion is serially sectioned and embedded to obtain horizontal sections. The HoVert technique yields vertical sections permitting visualization of the epidermis, the dermal-epidermal junction and perijunctional inflammation. The technique also provides horizontal sections that permit analysis of follicle number, follicle type, perifollicular inflammation and scarring. Evaluation of both vertical and horizontal sections from a single scalp biopsy maximizes the histopathological information obtained and enhances the diagnosis of LPP or DLE in specific cases. We believe that the HoVert technique represents a simple and diagnostically effective tool in differentiating LPP from DLE. It may also be applicable to the assessment of other forms of alopecia.
    Journal of Cutaneous Pathology 01/2011; 38(5):401-6. · 1.77 Impact Factor
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    John T Seykora, George Cotsarelis
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    ABSTRACT: The cell of origin for basal cell carcinoma (BCC) remains controversial. In this issue of Cancer Cell, Wang et al. provide strong evidence that BCC arise from hair follicle stem cells.
    Cancer cell 01/2011; 19(1):5-6. · 25.29 Impact Factor
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    ABSTRACT: The Notch receptor family regulates cell fate through cell-cell communication. CSL (CBF-1/RBP-jκ, Su(H), Lag-1) drives canonical Notch-mediated gene transcription during cell lineage specification, differentiation, and proliferation in the hematopoietic system, the intestine, the pancreas, and the skin. However, the functional roles of Notch in esophageal squamous epithelial biology are unknown. Normal esophageal keratinocytes were stimulated with calcium chloride to induce terminal differentiation. The squamous epithelia were reconstituted in organotypic 3-dimensional culture, a form of human tissue engineering. Notch was inhibited in culture with a γ-secretase inhibitor or dominant negative mastermind-like 1 (DNMAML1). The roles of Notch receptors were evaluated by in vitro gain-of-function and loss-of-function experiments. Additionally, DNMAML1 was targeted to the mouse esophagus by cytokeratin K14 promoter-driven Cre (K14Cre) recombination of Lox-STOP-Lox-DNMAML1. Notch-regulated gene expression was determined by reporter transfection, chromatin immunoprecipitation assays, quantitative reverse-transcription polymerase chain reaction, Western blotting, immunofluorescence, and immunohistochemistry. NOTCH1 (N1) was activated at the onset of squamous differentiation in the esophagus. Intracellular domain of N1 (ICN1) directly activated NOTCH3 (N3) transcription, inducing HES5 and early differentiation markers such as involucrin (IVL) and cytokeratin CK13 in a CSL-dependent fashion. N3 enhanced ICN1 activity and was required for squamous differentiation. Loss of Notch signaling in K14Cre;DNMAML1 mice perturbed esophageal squamous differentiation and resulted in N3 loss and basal cell hyperplasia. Notch signaling is important for esophageal epithelial homeostasis. In particular, the cross talk of N3 with N1 during differentiation provides novel, mechanistic insights into Notch signaling and squamous epithelial biology.
    Gastroenterology 12/2010; 139(6):2113-23. · 12.82 Impact Factor
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    Yu Qi, Xin Li, Liang Zhao, John T Seykora
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    ABSTRACT: Src-family tyrosine kinases (SFKs) play critical roles in regulating cellular differentiation and proliferation. Src-activating and signaling molecule (Srcasm) is a novel molecule that down-regulates SFK activity and promotes cell differentiation. The aim of this study was to determine whether Srcasm expression was altered in esophageal squamous epithelial carcinoma compared with normal epithelium in a Chinese population. We examined Srcasm immunohistochemical staining in 30 cases in both normal esophageal epithelium and esophageal squamous cell carcinoma (SCC) from the same patient in formalin-fixed paraffin embedded tissue blocks. Srcasm protein expression levels are decreased in esophageal SCC compared to the esophageal normal epithelium. This pattern of Srcasm expression suggests that it may act as a negative regulator in esophageal SCC cell signaling.
    Anticancer research 09/2010; 30(9):3535-9. · 1.71 Impact Factor

Publication Stats

1k Citations
298.27 Total Impact Points

Institutions

  • 2000–2014
    • University of Pennsylvania
      • Department of Dermatology
      Philadelphia, Pennsylvania, United States
  • 2012
    • Philadelphia College of Osteopathic Medicine
      Philadelphia, Pennsylvania, United States
  • 2002–2012
    • Hospital of the University of Pennsylvania
      • • Department of Dermatology
      • • Department of Cell and Development Biology
      Philadelphia, Pennsylvania, United States
  • 2005
    • Cornell University
      • Department of Microbiology and Immunology
      Ithaca, NY, United States