Epidermal growth factor receptor inhibition leads to cellular phenotype correction of DSP-mutated keratinocytes.

Desmoplakin (DSP) is a desmosomal component expressed in skin and heart, essential for desmosome stability and intermediate filament connection. Pathogenic variants in the DSP gene encoding DSP, lead to heterogeneous skin, adnexa and heart-related phenotypes, including skin fragility, woolly hair (WH), palmoplantar keratoderma (PPK) and arrhythmogenic/dilated cardiomyopathy (ACM/DCM). The ambiguity of computer-based prediction analysis of pathogenicity and effect of DSP variants, indicates a necessity for functional analysis. Here, we report a heterozygous DSP variant that was not previously described, NM_004415.4:c.3337C>T (NM_004415.4(NP_004406.2):p.(Arg1113*)) in a patient with PPK, WH and ACM. RNA and protein analysis revealed ~50% reduction of DSP mRNA and protein expression. Patient's keratinocytes showed fragile cell-cell connections and perinuclear retracted intermediate filaments. Epidermal growth factor receptor (EGFR) is a transmembrane protein expressed in the basal epidermal layer involved in proliferation and differentiation, processes that are disrupted in the development of PPK, and in the regulation of the desmosome. In skin of the abovementioned patient, evident EGFR upregulation was observed. EGFR inhibition in patient's keratinocytes strongly increased DSP expression at the plasma membrane, improved intermediate filament connection with the membrane edges and reduced the cell-cell fragility. This cell phenotypic recovery was due to a translocation of DSP to the plasma membrane together with an increased number of desmosomes. These results indicate a therapeutic potential of EGFR inhibitors for disorders caused by DSP haploinsufficiency.

Disruption of TUFT1, a Desmosome-Associated Protein, Causes Skin Fragility, Woolly Hair, and Palmoplantar Keratoderma.

Desmosomes are dynamic complex protein structures involved in cellular adhesion. Disruption of these structures by loss-of-function variants in desmosomal genes leads to a variety of skin- and heart-related phenotypes. In this study, we report TUFT1 as a desmosome-associated protein, implicated in epidermal integrity. In two siblings with mild skin fragility, woolly hair, and mild palmoplantar keratoderma but without a cardiac phenotype, we identified a homozygous splice-site variant in the TUFT1 gene, leading to aberrant mRNA splicing and loss of TUFT1 protein. Patients' skin and keratinocytes showed acantholysis, perinuclear retraction of intermediate filaments, and reduced mechanical stress resistance. Immunolabeling and transfection studies showed that TUFT1 is positioned within the desmosome and that its location is dependent on the presence of the desmoplakin carboxy-terminal tail. A Tuft1-knockout mouse model mimicked the patients' phenotypes. Altogether, this study reveals TUFT1 as a desmosome-associated protein, whose absence causes skin fragility, woolly hair, and palmoplantar keratoderma.

Functional investigation of two simultaneous or separately segregating DSP variants within a single family supports the theory of a dose-dependent disease severity.

Desmoplakin (DP) is an important component of desmosomes, essential in cell-cell connecting structures in stress-bearing tissues. Over the years, many hundreds of pathogenic variants in DSP have been associated with different cutaneous and cardiac phenotypes or a combination, known as a cardiocutaneous syndrome. Of less than 5% of the reported DSP variants, the effect on the protein has been investigated. Here, we describe and have performed RNA, protein and tissue analysis in a large family where DSPc.273+5G>A/c.6687delA segregated with palmoplantar keratoderma (PPK), woolly hair and lethal cardiomyopathy, while DSPWT/c.6687delA segregated with PPK and milder cardiomyopathy. hiPSC-derived cardiomyocytes and primary keratinocytes from carriers were obtained for analysis. Unlike the previously reported nonsense variants in the last exon of DSP that bypassed the nonsense-mediated mRNA surveillance system leading to protein truncation, variant c.6687delA was shown to cause the loss of protein expression. Patients carrying both variants and having a considerably more severe phenotype were shown to have 70% DP protein reduction, while patients carrying only c.6687delA had 50% protein reduction and a milder phenotype. The analysis of RNA from patient cells did not show any splicing effect of the c.273+5G>A variant. However, a minigene splicing assay clearly showed alternative spliced transcripts originating from this variant. This study shows the importance of RNA and protein analyses to pinpoint the exact effect of DSP variants instead of solely relying on predictions. In addition, the particular pattern of inheritance, with simultaneous or separately segregating DSP variants within the same family, strongly supports the theory of a dose-dependent disease severity.

The expression pattern of N-acetyltransferase 1 in healthy human skin.

BACKGROUND: N-acetyltransferase 1 (NAT1) is an enzyme expressed among others in keratinocytes in human skin. NAT1 is important in the biotransformation of aromatic amines, an important example being p-phenylenediamine (PPD), a hair dye molecule. Unoxidized PPD penetrates the skin and is N-acetylated by NAT1. OBJECTIVES: To investigate in detail the expression pattern of NAT1 in human skin. MATERIALS AND METHODS: Cryosections obtained from healthy human skin were stained for NAT1 and expression patterns were observed. NAT1 double stainings were performed with antibodies against different cellular organelles to determine expression patterns. RESULT: A speckled, granular expression of NAT1 was seen predominantly in the stratum basale. NAT1 was expressed in a cytoplasmic pattern, perinuclear, and in the nucleus. No co-localisation was seen with the selected cellular organelles. Local differences in NAT1 expression patterns were observed between donors and between different biopsies obtained from the same donor. CONCLUSIONS: NAT1 is expressed predominantly in the stratum basale and can be found in the cytoplasm, nucleus, and perinuclear in human skin. Further studies should be performed to investigate expression of NAT1 in a larger sample size.

Large-Scale Electron Microscopy Maps of Patient Skin and Mucosa Provide Insight into Pathogenesis of Blistering Diseases.

Large-scale electron microscopy ("nanotomy") allows straight forward ultrastructural examination of tissue, cells, organelles, and macromolecules in a single data set. Such data set equals thousands of conventional electron microscopy images and is freely accessible (www.nanotomy.org). The software allows zooming in and out of the image from total overview to nanometer scale resolution in a 'Google Earth' approach. We studied the life-threatening human autoimmune blistering disease pemphigus, using nanotomy. The pathomechanism of cell-cell separation (acantholysis) that underlies the blistering is poorly understood. Ultrastructural examination of pemphigus tissue revealed previously unreported findings: (i) the presence of double-membrane structures between cells in all pemphigus types; (ii) the absence of desmosomes around spontaneous blisters in pemphigus foliaceus (PF); (iii) lower level blistering in PF when force induced; and (iv) intercellular widening at non-acantholytic cell layers. Thus, nanotomy delivers open-source electron microscopic maps of patient tissue, which can be analyzed for additional anomalies from any computer by experts from different fields.

Differential in vitro immortalization capacity of eleven (probable) [corrected] high-risk human papillomavirus types.

Epidemiological studies identified 12 high-risk HPV (hrHPV) types and 8 probable/possible hrHPV types that display different cancer risks. Functional studies on transforming properties of hrHPV are mainly limited to HPV16 and -18, which induce immortalization of human foreskin keratinocytes (HFKs) by successive bypass of two proliferative life span barriers, senescence and crisis. Here, we systematically compared the in vitro immortalization capacities, as well as influences on p53, pRb, hTERT, growth behavior, and differentiation capacity, of nine hrHPV types (HPV16, -18, -31, -33, -35, -45, -51, -52, and -59), and two probable hrHPV types (HPV66 and -70). By retroviral transduction, the respective E6/E7 coding sequences were expressed in HFKs from two or three independent donors. Reduced p53 levels and low-level hTERT expression in early-passage cells, as seen in HPV16-, -31-, -33-, and -35-, and to a lesser extent HPV18-transduced HFKs, was associated with continuous growth and an increased immortalization capacity. Less frequent immortalization by HPV45 and -51 and immortalization by HPV66 and -70 was preceded by an intervening period of strongly reduced growth (crisis) without prior increase in hTERT expression. Immortalization by HPV59 was also preceded by a period crisis, despite the onset of low hTERT expression at early passage. HPV52 triggered an extended life span but failed to induce immortality. Variations in p53 and pRb levels were not correlated with differences in alternative E6/E7 mRNA splicing in all hrHPV-transduced HFKs. On collagen rafts, transductants showed disturbed differentiation reminiscent of precancerous lesions. In conclusion, in vitro oncogenic capacities differ between the established hrHPV types, and both some established and probable hrHPV types display weak or moderate immortalization potential.

The IgG "lupus-band" deposition pattern of pemphigus erythematosus: association with the desmoglein 1 ectodomain as revealed by 3 cases.

BACKGROUND: Pemphigus foliaceus is an autoimmune skin disease characterized by subcorneal blistering and IgG antibodies directed against desmoglein 1. In the skin, these antibodies deposit intraepidermally. On rare occasions,an additional "lupus band" of granular depositions of IgG and complement is seen along the epidermal basement membrane zone. This combined pattern has been connected with a variant of pemphigus foliaceus named pemphigus erythematosus. OBSERVATIONS: We describe 3 pemphigus foliaceus cases in which phototherapy was administered after a misdiagnosis of psoriasis. This treatment resulted in a flare of skin lesions. Direct immunofluorescence of skin biopsy specimens that were obtained several weeks later demonstrated intraepidermal and granular basement membrane zone depositions. The basement membrane zone depositions consisted of IgG, complement, and the ectodomain of desmoglein 1 and were located below the lamina densa. CONCLUSIONS: High doses of UV light are likely to induce the cleaving of the desmoglein 1 ectodomain. In patients with pemphigus foliaceus, the circulating anti­desmoglein 1 antibodies precipitate this cleaved-off ectodomain along the basement membrane zone, resulting in a lupus band­like appearance. In pemphigus erythematosus, a similar mechanism may be active, which might explain the lupus-band phenomenon.

Promiscuous behavior of HPV16E6 specific T cell receptor beta chains hampers functional expression in TCR transgenic T cells, which can be restored in part by genetic modification.

BACKGROUND: T cell receptor gene transfer is a promising strategy to treat patients suffering from HPV induced malignancies. Therefore we isolated the TCRalphabeta open reading frames of an HPV16E6 specific CTL clone and generated TCR transgenic T cells. In general low level expression of the transgenic TCR in recipient human T cells is observed as well as the formation of mixed TCRs dimers. Here we addressed both issues employing three different expression platforms. METHODS: We isolated the HVP16E6 specific TCRalpha and TCRbeta open reading frames and retrovirally transduced human T cells with either wild-type (wt), or codon-modified (cm) chains to achieve enhanced TCR expression levels, or used codon-modification in combination with cysteinization (cmCys) of TCRs to facilitate preferential pairing of the introduced TCRalpha and TCRbeta chains. RESULTS: Careful analysis of recipient T cells carrying the HPV16E6 TCRbeta and endogenous TCR chains revealed the transgenic TCRbeta chain to behave very promiscuously. Further analysis showed that the percentage of tetramer positive T cells in codon-modified/cysteinized TCR transgenic T cells was four-fold higher compared to wild-type and two-fold higher compared to codon-modification only. Functional activity, as determined by IFN-gamma production, was high in cmCysTCR transgenic T cells, where it was low in cm and wt TCR transgenic T cells. Recognition of endogenously processed HPV16E6 antigen by cmCysTCR transgenic T cells was confirmed in a cytotoxicity assay. CONCLUSION: Promiscuous behavior of the HPV16E6 specific TCRbeta chain can in part be forced back into specific action in TCR transgenic T cells by codon modification in combination with the inclusion of an extra cysteine in the TCR chains.

IFN-gamma-producing human invariant NKT cells promote tumor-associated antigen-specific cytotoxic T cell responses.

CD1d-restricted invariant NKT (iNKT) cells can enhance immunity to cancer or prevent autoimmunity, depending on the cytokine profile secreted. Antitumor effects of the iNKT cell ligand alpha-galactosylceramide (alphaGC) and iNKT cell adoptive transfer have been demonstrated in various tumor models. Together with reduced numbers of iNKT cells in cancer patients, which have been linked to poor clinical outcome, these data suggest that cancer patients may benefit from therapy aiming at iNKT cell proliferation and activation. Herein we present results of investigations on the effects of human iNKT cells on Ag-specific CTL responses. iNKT cells were expanded using alphaGC-pulsed allogeneic DC derived from the acute myeloid leukemia cell line MUTZ-3, transduced with CD1d to enhance iNKT cell stimulation, and with IL-12 to stimulate type 1 cytokine production. Enhanced activation and increased IFN-gamma production was observed in iNKT cells, irrespective of CD4 expression, upon stimulation with IL-12-overexpressing dendritic cells. IL-12-stimulated iNKT cells strongly enhanced the MART-1 (melanoma Ag recognized by T cell 1)-specific CD8(+) CTL response, which was dependent on iNKT cell-derived IFN-gamma. Furthermore, autologous IL-12-overexpressing dendritic cells, loaded with Ag as well as alphaGC, was superior in stimulating both iNKT cells and Ag-specific CTL. This study shows that IL-12-overexpressing allogeneic dendritic cells expand IFN-gamma-producing iNKT cells, which may be more effective against tumors in vivo. Furthermore, the efficacy of autologous Ag-loaded DC vaccines may well be enhanced by IL-12 overexpression and loading with alphaGC.

Tumor associated antigen and interleukin-12 mRNA transfected dendritic cells enhance effector function of natural killer cells and antigen specific T-cells.

Immunotherapy aiming at the combined activation of tumor associated antigen (TAA) specific cytotoxic T lymphocytes (CTL) and Natural Killer (NK) cells may be crucial to eradicate both MHC-I positive and negative tumors. Vaccination with mature dendritic cells (DC) transfected with mRNA encoding for TAA and the pro-inflammatory cytokines interleukin (IL)-12 and IL-18 may increase NK cell and TAA specific CTL activity. We demonstrate here that IL-12 over-expressing human DC induces increased NK cell activation and effector function and confirm the increase in TAA specific CTL by TAA/IL-12 double transfected DC. The effects of IL-18 transfection were limited to phenotypic activation and down-regulation of tissue homing receptors and did not add to the effect of IL-12 on NK cell effector function. In conclusion, co-transfection of TAA and IL-12 mRNA into mature DCs offers a vaccine for the induction of an anti-tumor immune response mediated by CTL and NK effector cells.

Constitutively active STAT5b induces cytokine-independent growth of the acute myeloid leukemia-derived MUTZ-3 cell line and accelerates its differentiation into mature dendritic cells.

The CD34(+) human acute myeloid leukemia-derived cell line MUTZ-3 is dependent on hematopoietic growth factors for its proliferation and is able to differentiate into dendritic cells (DCs) in response to the combination of granulocyte-macrophage colony-stimulating factor, interleukin-4, and tumor necrosis factor-alpha. This cell line carries human leukocyte antigen (HLA)-A2.1, HLA-A3, and HLA-B44, which cover most of the caucasian population, and it could therefore be used as an off-the-shelf allogeneic DC-based vaccine. Signal transduction and activation of transcription (STAT) 5b is involved in cytokine signal transduction, particularly of cytokines involved in DC precursor growth and differentiation. The constitutively active form of STAT5b induced cytokine-independent growth of MUTZ-3 cells. Furthermore, STAT5b-transduced cells differentiated into mature DCs in 3 to 4 days after stimulation with DC differentiation-inducing cytokines, reducing the culture period to obtain mature DCs with 5 days compared with unmodified MUTZ-3-derived mature DC cultures. Both DC types expressed DC maturation markers and were equally effective in inducing primary T-cell responses. DCs derived from the STAT5b-transduced cells had a more stable mature phenotype after cytokine deprivation, which was reflected in a better performance in functional assays. In conclusion, these results show that STAT5b-transduced MUTZ-3 can be propagated in cytokine-free medium and rapidly differentiated into functional mature DCs that sustain a mature phenotype over a period of 3 to 5 days in the absence of differentiation-inducing cytokines. The simplified propagation and rapid differentiation into mature DCs may facilitate clinical application of this cell line as an allogeneic DC-based vaccine.

Codon modification of T cell receptors allows enhanced functional expression in transgenic human T cells.

Expression of native transgenic T cell receptors in recipient human T cells is often insufficient to achieve highly reactive T cell bulks. Here we show that codon modification of an HPV16E7-specific T cell receptor (TCR), together with omission of mRNA instability motifs and (cryptic) splice sites, leads to a dramatic increase in the expression levels of the transgenic TCRs in human CD8+ T cells. The codon-modified TCRs have been tested in three different configurations in the retroviral vector LZRS: (1) TCRalpha-IRES-GFP in combination with TCRbeta-IRES-NGFR, (2) TCRalpha-IRES-TCRbeta, and (3) TCRalpha-2A-TCRbeta. T cells carrying the codon-modified TCRs are functionally active against target cells loaded with relevant peptide, model tumor cells expressing the specific epitope as well as cervical carcinoma cells. The significant improvements we report here in the functional expression of specific human TCRs will hopefully expedite clinical application of TCR transfer-based immunotherapy.

Antigen gene transfer to human plasmacytoid dendritic cells using recombinant adenovirus and vaccinia virus vectors.

Recombinant adenoviruses (RAd) and recombinant vaccinia viruses (RVV) expressing tumour-associated antigens (TAA) are used as anti-tumour vaccines. It is important that these vaccines deliver the TAA to dendritic cells (DC) for the induction of a strong immune response. Infection of myeloid DC (MDC) with RAd alone is relatively inefficient but CD40 retargeting significantly increases transduction efficiency and DC maturation. Infection with RVV is efficient without DC maturation. Plasmacytoid dendritic cells (PDC) play a role in the innate immune response to viral infections through the secretion of IFNalpha but may also play a role in specific T-cell induction. The aim of our study was to investigate whether PDC are better targets for RAd and RVV based vaccines. RAd alone hardly infected PDC (2%) while CD40 retargeting did not improve transduction efficiency, but it did increase PDC maturation (25% CD83 positive cells). Accordingly, specific CTL activation by RAd infected PDC was limited (the number of IFNgamma producing CTL was reduced by 75% compared to stimulation with peptide loaded PDC). RVV infected PDC specifically stimulated CTL but PDC were not activated. These results indicate that PDC are not ideal targets for RAd and RVV based vaccines. However, PDC induced specific CTL activation after pulsing with recombinant protein, indicating that PDC can also cross-present antigens released from surrounding infected cells.

Plasmacytoid dendritic cells are present in cervical carcinoma and become activated by human papillomavirus type 16 virus-like particles.

OBJECTIVES: Plasmacytoid dendritic cells (PDC) play an important role in the innate immune response to viral infections through the secretion of high levels of IFNalpha. We investigated whether PDC play a role in Human Papillomavirus (HPV) associated cervical carcinoma. METHODS: Frozen sections of 18 cervical carcinomas were analyzed for the presence of myeloid and plasmacytoid DC. To study whether the HPV virus can activate PDC, expression of putative VLP receptors (CD49f and CD16) was analyzed on PDC in peripheral blood mononuclear cells of healthy donors. Furthermore, CD83 induction and IFNalpha production by purified blood-derived PDC was measured after incubation with HPV 16 virus like particles (VLP). RESULTS: PDC were detected in 83% of the CxCa cases, primarily in the stroma. PDC express one of the putative VLP receptors (CD49f). IFNalpha production but no CD83 expression was induced in PDC upon incubation with VLP. CONCLUSION: Our data suggest that PDC, which are at hand locally in the cervix, play a role in the natural immune response against HPV and identify PDC as possible targets for VLP-based vaccines.

Identification of a potential human telomerase reverse transcriptase-derived, HLA-A1-restricted cytotoxic T-lymphocyte epitope.

The catalytic subunit of human telomerase reverse transcriptase (hTERT) is expressed in the majority of tumor cells of different histological origins as opposed to most normal somatic cells. This implicates hTERT as a widely expressed tumor-associated antigen and an attractive candidate for antigen-specific tumor immunotherapy. T lymphocytes specific for hTERT-derived epitopes have been isolated and shown reactive with hTERT-expressing tumor cells. To further increase the applicability of hTERT as a target antigen for immunotherapy, we set out to identify potential hTERT-derived, HLA-A1-restricted cytotoxic T-lymphocyte (CTL) epitopes. The "reverse immunology" approach, involving computer-assisted epitope prediction, in vitro CTL induction, and tetramer-guided CTL isolation, resulted in specific CTLs against hTERT-derived, HLA-A1-binding peptides. Intermediate- to low-avidity CTLs were induced against the hTERT325-333 peptide and recognized endogenously processed hTERT. Recognition of endogenous hTERT depended on an increase of hTERT expression above normal levels in tumor cells through hTERT transduction, most probably as a result of limited CTL avidity. The altered peptide ligand hTERT699T-707 was designed to increase HLA-A1-binding affinity of the hTERT699-707 peptide and was used to induce CTLs. However, these CTLs poorly cross-recognized native hTERT699-707 and failed to recognize endogenously processed hTERT. In conclusion, our study has identified the hTERT325-333 peptide as a potential hTERT-derived epitope that may prove useful for induction and monitoring of hTERT-specific, HLA-A1-restricted CTL responses.

Preservation and redirection of HPV16E7-specific T cell receptors for immunotherapy of cervical cancer.

Human papilloma virus (HPV) type 16 infections of the genital tract are associated with the development of cervical cancer (CxCa) in women. HPV16-derived oncoproteins E6 and E7 are expressed constitutively in these lesions and might therefore be attractive candidates for T-cell-mediated adoptive immunotherapy. However, the low precursor frequency of HPV16E7-specific T cells in patients and healthy donors hampers routine isolation of these cells for adoptive transfer. To overcome this problem, we have isolated T cell receptor (TCR) genes from four different HPV16E7-specific healthy donor and patient-derived human cytotoxic T lymphocyte (CTL) clones. We examined whether genetic engineering of peripheral blood-derived CD8+ T cells in order to express HPV16E711-20-specific TCRs is feasible for adoptive transfer purposes. Reporter cells (Jurkat/MA) carrying a transgenic TCR were shown to bind relevant but not irrelevant tetramers. Moreover, these TCR-transgenic Jurkat/MA cells showed reactivity towards relevant target cells, indicating proper functional activity of the TCRs isolated from already available T cell clones. We next introduced an HPV16E711-20-specific TCR into blood-derived, CD8+ recipient T cells. Transgenic CTL clones stained positive for tetramers presenting the relevant HPV16E711-20 epitope and biological activity of the TCR in transduced CTL was confirmed by lytic activity and by interferon (IFN)-gamma secretion upon antigen-specific stimulation. Importantly, we show recognition of the endogenously processed and HLA-A2 presented HPV16E711-20 CTL epitope by A9-TCR-transgenic T cells. Collectively, our data indicate that HPV16E7 TCR gene transfer is feasible as an alternative strategy to generate human HPV16E7-specific T cells for the treatment of patients suffering from cervical cancer and other HPV16-induced malignancies.

Interleukin-12 increases proliferation and interferon-gamma production but not cytolytic activity of human antigen-specific effector memory cytotoxic T lymphocytes: power of the effect depends on the functional avidity of the T cell and the antigen concentration.

Cytotoxic T lymphocytes (CTLs) play an important role in the defense against viral infections and malignant diseases. Interleukin (IL)-12 plays a crucial role in induction of antigen-specific primary CTL responses and enhances proliferation, interferon-gamma (IFN-gamma) production, and cytolytic activity of mitogen-stimulated T cells. However, the effects of IL-12 on proliferation and effector functions of previously in vitro or in vivo primed antigen-specific CTLs are less clear. Our results show that IL-12 induces an increase in proliferation of and IFN-gamma production by influenza peptide-specific CTLs, but no increase in cytolytic activity on a per cell basis was observed in bulk cultures. Stimulation of a CTL clone confirmed these results; IL-12 supported an increase in IFN-gamma production, but did not increase cytolytic activity. The extent of the effect of IL-12 on IFN-gamma production differs per CTL clone and depends on the avidity of the clone and the peptide concentration on its target. Our data suggest that IL-12 is a good adjuvant for boosting CTL responses, in terms of proliferation and IFN-gamma production, the latter particularly for CTLs with low to intermediate avidity, such as tumor-associated self-antigen-specific CTLs.