Klemens Rappersberger

Immunoelectron Microscopic Characterization of Human Dermal Lymphatic Microvascular Endothelial Cells: Differential Expression of CD31, CD34, and Type IV Collagen with Lymphatic Endothelial Cells vs Blood Capillary Endothelial Cells in Normal Human Skin, Lymphangioma, and Hemangioma In Situ

We performed a comparative investigation of the immunomorphological characteristics of lymphatic and blood microvascular endothelial cells in normal human skin, cutaneous lymphangiomas, and hemangiomas, employing a pre-embedding immunogold electron microscopic technique. We stained for cell membrane proteins that are commonly used for light microscopic characterization of blood endothelial cells. With blood microvascular endothelial cells, we observed uniform labeling of the luminal cell membranes with monoclonal antibodies (MAbs) JC70 (CD31), EN-4 (CD31), BMA120, PAL-E, and QBEND-10 (CD34), and strong staining of the vascular basal lamina for Type IV collagen under normal and pathological conditions. In contrast, lymphatic microvascular endothelial cells in normal human skin and in lymphangiomas displayed, in addition to a luminal labeling, pronounced expression of CD31 and CD34 along the abluminal cell membranes. Moreover, CD31 was preferentially detected within intercellular junctions. The expression of CD34 was mostly confined to abluminal endothelial microprocesses and was upregulated in lymphangiomas and hemangiomas. Type IV collagen partially formed the luminal lining of initial lymphatics and occasionally formed bridges over interendothelial gaps. Our findings suggest a function of transmigration protein CD31 in recruitment of dendritic cells into the lymphatic vasculature. CD34 labeling may indicate early endothelial cell sprouting. The distribution of Type IV collagen also supports its role as a signal for migration and tube formation for lymphatic endothelial cells.

Pembrolizumab cutaneous adverse events and their association with disease progression

IMPORTANCE Immunomodulatory anticancer drugs, such as the anti-programmed death-1 drug pembrolizumab, have shown promising results in trials, and more patients will receive such treatments. Little is known about cutaneous adverse events (AEs) caused by these drugs and their possible correlation with treatment response. OBJECTIVE To describe the frequency and spectrum of cutaneous AEs linked with pembrolizumab and their possible correlation with treatment response. DESIGN, SETTING, AND PARTICIPANTS A single-institution, retrospective medical record review was conducted of patients with cancer who were treated with pembrolizumab from March 1, 2011, to May 28, 2014. The review comprised 83 consecutive patients who were enrolled in 2 clinical trials, received at least 1 dose of pembrolizumab, and had at least 1 follow-up visit. Patients were grouped according to the following therapeutic regimen for pembrolizumab: 43 received 10 mg/kg every 3 weeks, 24 received 10 mg/kg every 2 weeks, and 16 received 2 mg/kg every 3 weeks. Sixty-six patients were treated for melanoma, 15 patients for lung cancer, 1 patient for prostate cancer, and 1 patient for Merkel cell carcinoma. Median follow-up was 15 weeks (range, 2-105 weeks). The analysis was conducted from March 1 to September 30, 2014. MAIN OUTCOMES AND MEASURES Occurrence, severity, and type of cutaneous AEs, as well as disease progression and response to pembrolizumab treatment. RESULTS Thirty-five patients (42%) developed cutaneous AEs attributed to pembrolizumab. The most common cutaneous AEs were macular papular eruption (24 [29%]), pruritus (10 [12%]), and hypopigmentation (7 [8%]). All 7 patients who developed hypopigmentation were treated for melanoma. Survival analyses showed that patients who developed cutaneous AEs had significantly longer progression-free intervals in all 3 groups (pembrolizumab, 10 mg/kg, every 3 weeks, P = .001; pembrolizumab, 10 mg/kg, every 2 weeks, P = .003; pembrolizumab, 2 mg/kg, every 3 weeks, P = .009) compared with patients who did not develop cutaneous AEs. CONCLUSIONS AND RELEVANCE Pembrolizumab therapy was associated with cutaneous AEs in 42% of patients. The development of cutaneous AEs, especially of hypopigmentation in patients with melanoma, could point toward better treatment response.

5-Methoxypsoralen (Bergapten) for photochemotherapy: Bioavailability, phototoxicity, and clinical efficacy in psoriasis of a new drug preparation

In a previous study we evaluated a microcrystalline preparation of 5-methoxypsoralen (5-MOP; Bergapten) for its photochemotherapeutic properties. Preliminary data indicated that the clinical efficacy of 5-MOP is comparable to that of 8-methoxypsoralen. 5-MOP appeared as a promising alternative photosensitizer for the management of psoriasis because of the almost complete lack of phototoxic and drug intolerance reactions that are frequently encountered in patients undergoing 8-MOP photochemotherapy. With a new liquid preparation of 5-MOP we have now extended our earlier investigation on a larger clinical scale and have correlated the clinical response with the bioavailability of the drug. Serum level determinations showed an absorption rate of only approximately 25% that of 8-MOP. When administered in the same dosage as 8-MOP, 5-MOP turned out to be significantly less effective; however, by doubling the oral dosage, comparable results in terms of clearing of psoriasis were obtained. Also with this high-dose 5-MOP regimen, no drug intolerance was noted and other side effects, such as severe erythema, pruritus, and nausea, occurred only rarely. We propose 5-MOP as a valuable alternative for photochemotherapy (PUVA) of PUVA-responsive diseases.

Peripheral T cell lymphoma presenting primarily as lethal midline granuloma

This clinicopathologic study reports seven patients who primarily presented with ulcerative and destructive lesions of the upper aerodigestive tract and face, clinically consistent with so-called lethal midline granuloma (LMG). Histologically, the infiltrates were composed of atypical lymphoid cells that displayed angiocentricity and angiodestruction. In five patients, involvement of distant sites such as skin, lungs, lymph nodes, and bone marrow occurred, and in two cases, the disease remained localized. Immunomorphologic analysis, using monoclonal antibodies to frozen and paraffin sections, provided evidence for the diagnosis of peripheral T cell lymphoma (PTL) in all cases. The midline tumors were classified as diffuse mixed or diffuse large cell lymphoma occurred at distant sites. According to modern PTL classification systems, the lesions could be classified as pleomorphic T cell lymphomas. Those five patients who presented with or progressed to large cell lymphoma died within 18 months (mean, 7 months), whereas the two patients with localized disease are alive after 10 and 36 months, respectively. The size of the atypical lymphoid cells may be of prognostic significance since the large cell compartment seems to represent the major growth fraction in these PTLs.

Langerhans cells in HIV-1 infection

The skin-specific immune surveillance system protects against invading microorganisms and transformed cells expressing tumor-specific neoantigens. This system includes antigen-presenting Langerhans cells, dermal and epidermal T lymphocytes, cytokine-producing keratinocytes, and draining peripheral lymph nodes. In patients infected with human immunodeficiency virus-1 (HIV-1), this surveillance system appears to be compromised, as evidenced by a reduction in the epidermal Langerhans cell population. Because human epidermal Langerhans cell express surface-bound CD4 antigens, HLA-DR antigens, and Fc-IgG receptors, all of which are involved in HIV-1 binding to, or entry into, the target cell, the reduction in Langerhans cells in patients with acquired immunodeficiency syndrome (AIDS) or AIDS-related complex (ARC) may be a direct consequence of HIV-1 infection and subsequent injury to Langerhans cells. Detailed ultrastructural studies have confirmed moderate to severe morphologic damage in some Langerhans cells of such patients and the presence of HIV-1-like particles on Langerhans cell surface membranes and in the extracellular spaces. The biologic consequences of Langerhans cell infection by HIV-1 could be either impaired antigen presentation function of viable Langerhans cells or possible transmission of the retrovirus to the T-cell compartment in skin or lymph nodes, with subsequent depletion of CD4+ T cells via widespread syncytia formation between HIV-1-infected and noninfected cells. The facts that herpes simplex virus, specific cytokines, and ultraviolet B radiation can activate signals for HIV-1 expression and that epidermal cells can elaborate large amounts of cytokines, particularly with enhanced ultraviolet B exposure, may have important clinical implications for HIV-1-infected patients.

Positron emission tomography is not useful in detecting metastasis in the sentinel lymph node in patients with primary malignant melanoma stage I and II.

The most powerful predictor for recurrence and survival in patients with primary malignant melanoma is the presence or absence of lymph node metastases. In the present study, 18-fluoro-2-deoxyglucose positron emission tomography (FDG-PET) findings were compared with histopathological results of sentinel lymph node biopsy (SNB). The purpose was to determine the value of FDG-PET in predicting regional lymph node involvement in patients with primary malignant melanoma stage I and II. Forty-eight consecutive patients with primary cutaneous melanoma stage I (Breslow thickness >1 mm) and II underwent FDG-PET scans, preoperative lymphoscintigraphy, and SNB. The FDG-PET and SNB results were interpreted independently of each other and then compared. Of the 48 patients included in the study, eight (16.7%) had a positive SNB. PET was positive in only one patient with a positive SNB, yielding a sensitivity of 13%. All other positive sentinel nodes could not be detected by metabolic FDG-PET imaging. Our study revealed that FDG-PET is obviously not an adequate screening test for subclinical and sonographically inconspicuous lymph node metastases in patients with malignant melanoma stage I and II. The low sensitivity is probably due to the small size of metastatic deposits in sentinel nodes. Therefore, SNB remains the technique of choice for evaluating the histological status of lymph node basins in patients with early-stage cutaneous melanoma.

Functional Involvement of E-Cadherin in TGF-β1-Induced Cell Cluster Formation of In Vitro Developing Human Langerhans-Type Dendritic Cells

Epithelial Langerhans cells (LC) represent immature dendritic cells that require TGF-β1 stimulation for their development. Little is known about the mechanisms regulating LC generation from their precursor cells. We demonstrate here that LC development from human CD34+ hemopoietic progenitor cells in response to TGF-β1 costimulation (basic cytokine combination GM-CSF plus TNF-α, stem cell factor, and Flt3 ligand) is associated with pronounced cell cluster formation of developing LC precursor cells. This cell-clustering phenomenon requires hemopoietic progenitor cell differentiation, since it is first seen on day 4 after culture initiation of CD34+ cells. Cell cluster formation morphologically indicates progenitor cell development along the LC pathway, because parallel cultures set up in the absence of exogenous TGF-β1 fail to form cell clusters and predominantly give rise to monocyte, but not LC, development (CD1a−, lysozyme+, CD14+). TGF-β1 costimulation of CD34+ cells induces neoexpression of the homophilic adhesion molecule E-cadherin in the absence of the E-cadherin heteroligand CD103. Addition of anti-E-cadherin mAb or mAbs to any of the constitutively expressed adhesion molecule (CD99, CD31, LFA-1, or CD18) to TGF-β1-supplemented progenitor cell cultures inhibits LC precursor cell cluster formation, and this effect is, with the exception of anti-E-cadherin mAb, associated with inhibition of LC generation. Addition of anti-E-cadherin mAb to the culture allows cell cluster-independent generation of LC from CD34+ cells. Thus, functional E-cadherin expression and homotypic cell cluster formation represent a regular response of LC precursor cells to TGF-β1 stimulation, and cytoadhesive interactions may modulate LC differentiation from hemopoietic progenitor cells.

Bullous disease in systemic lupus erythematosus

We describe three women with systemic lupus erythematosus and vesiculobullous skin lesions. One patient had a generalized bullous dermatosis and circulating anti-basement membrane zone IgG autoantibodies. Two patients had vesiculobullous lesions limited to the face. All patients had subepidermal blisters and an infiltrate of neutrophils and linear IgG, IgM, IgA, and C3 deposits along the basement membrane zone. These deposits were located in the sublamina densa. Ultrastructural investigation revealed a dermatolytic bullous disease in the patient with the generalized bullous eruption and anti-basement membrane zone autoantibodies and junctional blistering in those patients who had localized blistering.

The gallium complex KP46 exerts strong activity against primary explanted melanoma cells and induces apoptosis in melanoma cell lines

The antineoplastic properties of gallium are well documented. Owing to their robust accumulation of gallium, melanoma cells should be amenable to gallium-based anticancer drugs. With the aim of improving the disappointingly low activity of inorganic gallium salts, we have developed the orally bioavailable gallium complex KP46 [tris(8-quinolinolato)gallium(III)] that had already been successfully studied in a phase I clinical trial. To assess its therapeutic potential in malignant melanoma, its antiproliferative effects were investigated in series of human cell lines and primary explanted melanoma samples by means of the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay and the Human Tumor Cloning Assay, respectively. When compared with other cell lines, the majority of melanoma cells rank among the KP46-sensitive cell lines (50% inhibitory concentration values: 0.8–3.7 μmol/l). Clinically achievable concentrations of KP46 proved to be highly effective in melanoma cells from primary explants of cutaneous and lymph node metastases. Colony growth was inhibited in 10 of 10 specimens by 5 μmol/l KP46 (corresponding to the steady-state plasma concentration measured earlier in a study patient) and in four of 10 specimens by 0.5 μmol/l KP46. In-vitro potency of KP46 is higher than that of dacarbazine or fotemustine and comparable with that of cisplatin. The effects induced by KP46 in melanoma cell lines involve cell-cycle perturbations (S-phase arrest) and apoptosis (activation of caspase-9, PARP [poly(ADP-ribose) polymerase] cleavage, formation of apoptotic bodies). No effects on DNA secondary structure could be observed in an electrophoretic mobility shift assay using double-stranded plasmid DNA. Thus, further studies on the therapeutic applicability of KP46 in malignant melanoma are warranted.

Bullous Pemphigoid Induced by PUVA Therapy

An 80-year-old psoriatic patient developed a blistering eruption during oral PUVA therapy. The diagnosis of bullous pemphigoid (BP) was established by routine histopathology, which demonstrated subepidermal blistering, and direct immunofluorescence, which revealed linear deposits of IgG, IgM and C3 along the basement membrane zone. Indirect immunofluorescence using normal human split skin revealed binding of IgG antibodies to the epidermal side, thus confirming a subepidermal blistering disorder. These proteins were identified by the immunoblotting technique as BP antigens I and II. Clinically, the lesions could be reproduced by phototesting using topical 8-methoxypsoralen. Again, the histopathological and immunopathological findings were consistent with the diagnosis of PUVA-induced BP. To the best of our knowledge, this is the first report demonstrating psoriasis-associated BP, in which the clinical diagnosis of BP is confirmed by immunoblotting analysis. The exact role of UV light in precipitating bullous lesions, particularly the question whether UV light may represent an unspecific epidermal injury leading to further attraction of autoantibodies to the basement membrane zone, as suggested recently by an experimental study in rodents, remains to be clarified in future studies.