Identification of immunological patterns characterizing immune-related psoriasis reactions in oncological patients in therapy with anti-PD-1 checkpoint inhibitors

Introduction

Immunotherapy with biologics targeting programmed cell death protein-1 (PD-1) is highly effective in the treatment of various malignancies. Nevertheless, it is frequently responsible for unexpected cutaneous manifestations, including psoriasis-like dermatitis. The pathogenesis of anti-PD-1-induced psoriasis has yet to be clarified, even though it is plausible that some innate and adaptive immunity processes are in common with canonical psoriasis. The genetic predisposition to psoriasis of patients could also be a contributing factor. Here, we investigated the immunological and genetic profiles of two patients with metastatic melanoma and one patient affected by lung cancer, who developed severe psoriasis after receiving anti-PD-1 nivolumab therapy.

Methods

The immune patterns of the three patients were compared with those detectable in classical, chronic plaque-type psoriasis or paradoxical psoriasis induced by anti-TNF-α therapy, mostly sustained by adaptive and innate immunity processes, respectively. Therefore, immunohistochemistry and mRNA analyses of innate and adaptive immunity molecules were conducted on skin biopsy of patients. Genetic analysis of polymorphisms predisposing to psoriasis was carried out by NGS technology.

Results

We found that anti-PD-1-induced psoriasis showed immunological features similar to chronic psoriasis, characterized by the presence of cellular players of adaptive immunity, with abundant CD3+, CD8+ T cells and CD11c+ dendritic cells infiltrating skin lesions, and producing IL-23, IL-6, TNF-α, IFN-γ and IL-17. On the contrary, a lower number of innate immunity cells (BDCA2+ plasmacytoid dendritic cells, CD15+ neutrophils, CD117+ mast cells) and reduced IFN-α/β, lymphotoxin (LT)-α/β, were observed in anti-PD-1-induced psoriasis lesions, as compared with anti-TNF-α-induced paradoxical psoriasis. Importantly, the disintegrin and metalloprotease domain containing thrombospondin type 1 motif-like 5 (ADAMTSL5) psoriasis autoantigen was significantly upregulated in psoriasis lesions of anti-PD-1-treated patients, at levels comparable with chronic plaque-type psoriasis. Finally, NGS analysis revealed that all patients carried several allelic variants in psoriasis susceptibility genes, such as HLA-C, ERAP1 and other genes of the major psoriasis susceptibility PSORS1 locus.

Discussion

Our study showed that adaptive immunity predominates over innate immunity in anti-PD-1-induced psoriasis lesions, consistently with the local ADAMTSL5 overexpression. The presence of numerous SNPs in psoriasis susceptibility genes of the three patients also suggested their strong predisposition to the disease.

Primary Mucosal Melanoma: Clinical Experience from a Single Italian Center

(1) Background: Mucosal melanoma (MM) is a rare tumor, accounting for about 1% of all diagnosed melanomas. The etiology and pathogenesis of this tumor are unknown. It is characterized by an aggressive phenotype with poor prognosis and a low response rate to approved treatments. (2) Methods: We retrospectively analyzed the clinical features, treatments and outcomes of patients diagnosed with MM from different sub-sites (head and neck, gynecological and gastro-intestinal region) between 2013 and 2023 at our Institute. Survival times were estimated with the Kaplan-Meier method. Multivariate Cox regression was used to test the independence of significant factors in univariate analysis. (3) Results: Twenty-five patients were included in this study; the disease was equally distributed among females and males. The median age at diagnosis was 74 years old. The majority had MM originating from the head and neck (56%), particularly from the nasal cavity. BRAF V600 mutations were detected in 16% of the study population, limited to gastro-intestinal and gynecological MM. At diagnosis, at least half the patients (52%) had the disease located also at distant sites. The median overall survival (OS) in the whole study population was 22 months, with a longer OS for patients diagnosed at an early stage (38 months, p < 0.001). Longer OSs were reported for head and neck MM compared to other anatomic regions (0.06). Surgery of the primary tumor and radiotherapy were performed in 64% and 36% of the study population, respectively. Radiotherapy was performed only in head and neck MM. At multivariate analysis, the single factor that showed a reduced hazard ratio for death was radiotherapy. (4) Conclusions: The overall survival of MM from different sub-sites treated at our Italian Institution was 22 months, with better outcomes for early-stage disease and head and neck MM. Performing radiotherapy may have a protective effect on OS for head and neck MM. New treatment strategies are urgently needed to improve the outcome in this disease.

Insight into immune profile associated with vitiligo onset and anti-tumoral response in melanoma patients receiving anti-PD-1 immunotherapy

Introduction

Immunotherapy with checkpoint inhibitors is an efficient treatment for metastatic melanoma. Development of vitiligo upon immunotherapy represents a specific immune-related adverse event (irAE) diagnosed in 15% of patients and associated with a positive clinical response. Therefore, a detailed characterization of immune cells during vitiligo onset in melanoma patients would give insight into the immune mechanisms mediating both the irAE and the anti-tumor response.

Methods

To better understand these aspects, we analyzed T cell subsets from peripheral blood of metastatic melanoma patients undergoing treatment with anti-programmed cell death protein (PD)-1 antibodies. To deeply characterize the antitumoral T cell response concomitant to vitiligo onset, we analyzed T cell content in skin biopsies collected from melanoma patients who developed vitiligo. Moreover, to further characterize T cells in vitiligo skin lesion of melanoma patients, we sequenced T cell receptor (TCR) of cells derived from biopsies of vitiligo and primary melanoma of the same patient.

Results and discussion

Stratification of patients for developing or not developing vitiligo during anti-PD-1 therapy revealed an association between blood reduction of CD8-mucosal associated invariant T (MAIT), T helper (h) 17, natural killer (NK) CD56bright, and T regulatory (T-reg) cells and vitiligo onset. Consistently with the observed blood reduction of Th17 cells in melanoma patients developing vitiligo during immunotherapy, we found high amount of IL-17A expressing cells in the vitiligo skin biopsy, suggesting a possible migration of Th17 cells from the blood into the autoimmune lesion. Interestingly, except for a few cases, we found different TCR sequences between vitiligo and primary melanoma lesions. In contrast, shared TCR sequences were identified between vitiligo and metastatic tissues of the same patient. These data indicate that T cell response against normal melanocytes, which is involved in vitiligo onset, is not typically mediated by reactivation of specific T cell clones infiltrating primary melanoma but may be elicited by T cell clones targeting metastatic tissues. Altogether, our data indicate that anti-PD-1 therapy induces a de novo immune response, stimulated by the presence of metastatic cells, and composed of different T cell subtypes, which may trigger the development of vitiligo and the response against metastatic tumor.

Safe-Shields: Basal and Anti-UV Protection of Human Keratinocytes by Redox-Active Cerium Oxide Nanoparticles Prevents UVB-Induced Mutagenesis

Cerium oxide nanoparticles (nanoceria), biocompatible multifunctional nanozymes exerting unique biomimetic activities, mimic superoxide-dismutase and catalase through a self-regenerating, energy-free redox cycle driven by Ce3+/4+ valence switch. Additional redox-independent UV-filter properties render nanoceria ideal multitask solar screens, shielding from UV exposure, simultaneously protecting tissues from UV-oxidative damage. Here, we report that nanoceria favour basal proliferation of primary normal keratinocytes, and protects them from UVB-induced DNA damage, mutagenesis, and apoptosis, minimizing cell loss and accelerating recovery with flawless cells. Similar cell-protective effects were found on irradiated noncancerous, but immortalized, p53-null HaCaT keratinocytes, with the notable exception that here, nanoceria do not accelerate basal HaCaT proliferation. Notably, nanoceria protect HaCaT from oxidative stress induced by irradiated titanium dioxide nanoparticles, a major active principle of commercial UV-shielding lotions, thus neutralizing their most critical side effects. The intriguing combination of nanoceria multiple beneficial properties opens the way for smart and safer containment measures of UV-induced skin damage and carcinogenesis.

Phytochemicals as Immunomodulatory Agents in Melanoma

Cutaneous melanoma is an immunogenic highly heterogenic tumor characterized by poor outcomes when it is diagnosed late. Therefore, immunotherapy in combination with other anti-proliferative approaches is among the most effective weapons to control its growth and metastatic dissemination. Recently, a large amount of published reports indicate the interest of researchers and clinicians about plant secondary metabolites as potentially useful therapeutic tools due to their lower presence of side effects coupled with their high potency and efficacy. Published evidence was reported in most cases through in vitro studies but also, with a growing body of evidence, through in vivo investigations. Our aim was, therefore, to review the published studies focused on the most interesting phytochemicals whose immunomodulatory activities and/or mechanisms of actions were demonstrated and applied to melanoma models.

Arabidopsis thaliana sirtuins control proliferation and glutamate dehydrogenase activity

Sirtuins are part of a gene family of NAD-dependent deacylases that act on histone and non-histone proteins and control a variety of activities in all living organisms. Their roles are mainly related to energy metabolism and include lifetime regulation, DNA repair, stress resistance, and proliferation. A large amount of knowledge concerning animal sirtuins is available, but data about their plant counterparts are scarce. Plants possess few sirtuins that have, like in animals, a recognized role in stress defense and metabolism regulation. However, engagement in proliferation control, which has been demonstrated for mammalian sirtuins, has not been reported for plant sirtuins so far. In this work, srt1 and srt2 Arabidopsis mutant seedlings have been used to evaluate in vivo the role of sirtuins in cell proliferation and regulation of glutamate dehydrogenase, an enzyme demonstrated to be involved in the control of cell cycle in SIRT4-defective human cells. Moreover, bioinformatic analyses have been performed to elucidate sequence, structure, and function relationships between Arabidopsis sirtuins and between each of them and the closest mammalian homolog. We found that cell proliferation and GDH activity are higher in mutant seedlings, suggesting that both sirtuins exert a physiological inhibitory role in these processes. In addition, mutant seedlings show plant growth and root system improvement, in line with metabolic data. Our data also indicate that utilization of an easy to manipulate organism, such as Arabidopsis plant, can help to shed light on the molecular mechanisms underlying the function of genes present in interkingdom species.

Interleukin role in the regulation of endothelial cell pathological activation

Interleukins (ILs) are the group of cytokines firstly identified as expressed by leukocytes and playing different immunomodulatory functions. With increasing evidence of a constant crosstalk between leukocytes and endothelial cells in the regulation of immune cell differentiation and activation, a role of ILs also in endothelial cell stimulation and vascular inflammation has been shown. ILs act on endothelial cells both in an autocrine and a paracrine manner. In fact, a cross regulation is present among ILs expressed by different cell types, leading to amplification or blocking of the initial inflammatory signal with the secretion of additional ILs or involvement of other adjacent cells and tissues. Based on selective structural features, ILs can be divided into four major groups, a fifth group comprises ILs that do not fit into any of the other four. Most of the ILs playing a role in endothelial cell activation belong to the IL1-like cytokine group, but the number of ILs involved in vascular inflammation is constantly growing, and a special contribution of IL6, IL8, and IL17 has been underlined. This review aims at presenting current knowledge and at underling missing information about the role of IL in activating endothelial cells in selected pathological settings such as tumours, psoriasis, systemic sclerosis, and viral infection.

Vitiligo-like leukoderma as an indicator of clinical response to immune checkpoint inhibitors in late-stage melanoma patients

PURPOSE

Although development of immune checkpoint inhibitors has revolutionized the treatment of metastatic melanoma, more than a half of treated patients experience disease progression during therapy. Cases of spontaneous vitiligo-like leukoderma have been described in melanoma patients and have been associated with a favorable outcome. This vitiligo-like leukoderma can also appear in melanoma patients undergoing immune therapies such as immune checkpoint inhibitors. However, no consensus exists about the relationship between vitiligo-like leukoderma onset and improved overall survival. Our study investigates the possible association between the onset of vitiligo-like leukoderma during immune checkpoint inhibitor treatment and a better prognosis.

METHODS

A non-concurrent cohort study was conducted by identifying retrospectively 280 patients who had inoperable or metastatic melanoma and had undergone immune therapy with checkpoint inhibitors in any line of treatment. Toxicities developed during therapy were evaluated.

RESULTS

Among the 280 study participants, 50% developed at least one type of toxicity, and vitiligo-like leukoderma was observed in 43 patients (15.4%). In the multivariate Cox model, a protective effect for mortality was observed for patients with vitiligo-like leukoderma development (HR : 0.23; 95% CI 0.11-0.44, p < 0.0001). In a sub-group analysis comprising only cutaneous melanoma in first line of treatment (N = 153), occurrence of vitiligo-like leukoderma was also an independent predictor factor for duration of clinical benefits measured by time to the next treatment (HR: 0.17; 95% CI 0.06-0.44).

CONCLUSION

Our findings indicate that onset of vitiligo-like leukoderma during melanoma treatment could be a marker of favorable outcome in patients treated with immune checkpoint inhibitors.

Clinical Predictors of Response to Anti-PD-1 First-Line Treatment in a Single-Centre Patient Cohort: A Real-World Study

AIMS

Cutaneous melanoma is one of the most immunogenic tumours. Immunotherapy with checkpoint inhibitors, such as anti-PD-1 antibodies, has significantly improved the prognosis in metastatic melanoma. However, only half of the patients respond to this therapy and have a favourable outcome. Identifying factors associated with treatment failure and early identification of responders are both important to select the best treatment approach for each patient. The aim of our study was to investigate clinical biomarkers of response to treatment with anti-PD-1 antibodies.

MATERIALS AND METHODS

We selected all patients with stage IV melanoma (n = 147), subjected to first-line treatment with anti-PD-1 in the last 10 years. We investigated the associations between patients' different clinical features and progression-free survival, using the Cox proportional hazards models.

RESULTS

In the multivariate analysis, an increased risk of disease progression was observed among patients with stage M1d metastases (hazard ratio 3.30; 95% confidence interval 1.58-6.91), compared with patients with stage M1a-M1b. Moreover, the risk of progression was greater in patients with the Eastern Cooperative Oncology Group Performance Status (ECOG PS) 1 (hazard ratio 2.04; 95% confidence interval 1.02-4.06) and in patients with ECOG PS ≥ 2 (hazard ratio 2.19; 95% confidence interval 1.05-4.55) compared with ECOG PS 0. High levels of lactate dehydrogenase (hazard ratio 2.06; 95% confidence interval 1.18-3.59) and the presence of respiratory diseases (hazard ratio 4.14; 95% confidence interval 1.42-12.0) at the beginning of anti-PD-1 treatment were also associated with an increased risk of disease progression. In a subgroup analysis, neutrophil count and neutrophil/lymphocyte ratio before anti-PD-1 treatment were higher in patients who underwent disease progression.

CONCLUSION

In our study population, independent predictors of disease progression among patients treated with first-line anti-PD-1 were as follows: ECOG PS, staging, lactate dehydrogenase and the presence of respiratory diseases.

Neuropilin-1 is required for endothelial cell adhesion to soluble vascular endothelial growth factor receptor 1

Neuropilin‐1 (NRP‐1) is a semaphorin receptor involved in neuron guidance, and a co‐receptor for selected isoforms of the vascular endothelial growth factor (VEGF) family. NRP‐1 binding to several VEGF‐A isoforms promotes growth factor interaction with VEGF receptor (VEGFR)‐2, increasing receptor phosphorylation. Additionally, NRP‐1 directly interacts with VEGFR‐1, but this interaction competes with NRP‐1 binding to VEGF‐A165 and does not enhance VEGFR‐1 activation. In this work, we investigated in detail the role of NRP‐1 interaction with the soluble isoform of VEGFR‐1 (sVEGFR‐1) in angiogenesis. sVEGFR‐1 acts both as a decoy receptor for VEGFs and as an extracellular matrix protein directly binding to α5β1 integrin on endothelial cells. By combining cell adhesion assays and surface plasmon resonance experiments on purified proteins, we found that sVEGFR‐1/NRP‐1 interaction is required both for α5β1 integrin binding to sVEGFR‐1 and for endothelial cell adhesion to a sVEGFR‐1‐containing matrix. We also found that a previously reported anti‐angiogenic peptide (Flt_2‐11), which maps in the second VEGFR‐1 Ig‐like domain, specifically binds NRP‐1 and inhibits NRP‐1/sVEGFR‐1 interaction, a process that likely contributes to its anti‐angiogenic activity. In view of potential translational applications, we developed a five‐residue‐long peptide, derived from Flt_2‐11, which has the same ability as the parent Flt_2‐11 peptide to inhibit cell adhesion to, and migration towards, sVEGFR‐1. Therefore, the Flt_2‐5 peptide represents a potential anti‐angiogenic compound per se, as well as an attractive lead for the development of novel angiogenesis inhibitors acting with a different mechanism with respect to currently used therapeutics, which interfere with VEGF‐A165 binding.

Multiple Sclerosis Treatment and Melanoma Development

Therapy of multiple sclerosis (MS) with disease-modifying agents such as natalizumab or fingolimod has been associated with the development of cutaneous melanoma. Here we briefly revise literature data and report of a case of a 48-year old woman who developed a melanoma and several atypical naevi after sub sequential treatment with natalizumab (1 year) and fingolimod (7 years). By immunohistochemistry we observed the presence of T cells and leukocyte infiltration as well as of vascular endothelial growth factor (VEGF)-A expression in the patient melanoma biopsy. Then, we analyzed proliferation, migration and VEGF-A expression in three melanoma cell lines and found out that both natalizumab and fingolimod inhibited tumor cell proliferation but promoted or blocked cell migration depending on the cell line examined. VEGF-A secretion was augmented in one melanoma cell line only after fingolimod treatment. In conclusion, our in vitro data do not support the hypothesis of a direct action of natalizumab or fingolimod on melanoma progression but acting on the tumor microenvironment these treatments could indirectly favor melanoma evolution.

Quantitative analysis of metals and metal-based nano- and submicron-particles in tattoo inks

Exposure to metals and metal-based nano- (NPs, 1-100 nm) and submicron-particles (SPs, 0.1-1 μm) contained in tattoo inks and related health safety is currently receiving a great deal of interest. Twenty inks of different brands and colours were sampled in Italy in 2019. The SemiQuant Inductively Coupled Plasma Mass Spectrometry (ICP-MS) analysis allowed quantifying the concentration of 18 metals (Al, As, Ba, Cd, Co, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, Sb, Se, Sn, Ti, Zn) in inks. The Single Particle ICP-MS was used to detect the diameters and concentration of NPs and SPs of 9 metals (Al, Co, Cr, Cu, Hg, Ni, Pb, Ti and Zn). Concentration of metals in tattoo inks were below the recommended concentrations reported in the Resolution ResAP (2008)1 indicating ink production have shifted to purer materials and best manufacturing practices. Regarding particles, Al was found at nano- (62-80 nm) and submicron-sizes (105-140 nm). Sizes of Cr, Cu, Pb and Zn were in the intervals 42-62 nm, 44-96 nm, 26-28 nm and 26-59 nm, respectively. Titanium was at submicron-diameters (166-383 nm). In addition, Cr and Ti particles accounted for the 47% and 80% of their total concentration, respectively. Tattooing practice exposed humans to metal-based NPs and SPs and the presence of a combination of particles of different metals and/or their dynamics (e.g., dissolution) may change their bioavailability and toxicity.

Non-animal models in dermatological research

Despite widely used for basic and preclinical studies in dermatology, available animal models only partly recapitulate human skin features often leading to disappointing outputs when preclinical results are translated to the clinic. Therefore, the need to develop alternative, non-animal models is widely recognized to more closely recapitulate human skin pathophysiology and to address the pressing ethical demand of reducing the number of animals used for research purposes, following the globally accepted 3Rs principle (Replacement, Reduction and Refinement). Skin is the outermost organ of the body, and, as such, easily accessible. Different skin cell types can be propagated in vitro and skin can be reconstructed for therapeutic transplantation as well as for in vitro modeling of physiopathological conditions. Bioengineered skin substitutes have been developed and evolved from elementary to complex systems, more and more closely resembling complete skin architecture and biological responses. In silico analyses take advantage from the huge amount of data already available from human studies for identifying and modeling molecular pathways involved in skin pathophysiology without further animal testing. The present review recapitulates the available non-animal models for dermatological research and sheds lights on their prospective technological evolution.

Interleukin-17 and interleukin-22 promote tumor progression in human nonmelanoma skin cancer

Interleukin-17 (IL-17) and IL-22 have been reported to play critical roles in autoimmunity and inflammation but information about their role in cancer is limited. In this study, we investigated the role of IL-17 and IL-22 in the progression of human skin basal-cell carcinoma (BCC) and squamous-cell carcinoma (SCC). We found that both tumor types are infiltrated with an high number of IL-17(+) and IL-22(+) T lymphocytes, as demonstrated by immunohistochemistry and by FACS analysis performed on peritumoral T-cell lines isolated from skin biopsies. In vitro studies demonstrated that proliferation and migration of the BCC- and SCC-cell lines M77015 and CAL27 were increased by IL-17 and IL-22. Moreover, IL-17, alone or in combination with TNF-α, was able to induce the production of two cytokines important for tumor progression, IL-6 and IL-8, in CAL27. We also showed that IL-17 upregulated NF-κB signaling, while IL-22 activated the STAT3 pathway and the antiapoptotic AKT protein in M77015 and CAL27. Finally, in vivo experiments demonstrated that IL-17 and IL-22 enhanced tumor growth in nude mice injected with CAL27. Altogether, our findings indicate that high levels of IL-22 and IL-17 in the BCC and SCC microenvironment promote tumor progression.

Expression of the soluble vascular endothelial growth factor receptor-1 in cutaneous melanoma: role in tumour progression

BACKGROUND

Vascular endothelial growth factor (VEGF)-A, placenta growth factor (PlGF) and their corresponding membrane receptors are involved in autocrine and paracrine regulation of melanoma growth and metastasis. Besides the membrane receptors, a soluble form of the VEGF receptor (VEGFR)-1 (sVEGFR-1) has been identified, that behaves both as a decoy receptor, sequestering VEGF-A and PlGF, and as an extracellular matrix (ECM) molecule, promoting endothelial cell adhesion and migration through the interaction with α5β1 integrin.

OBJECTIVES

To analyse whether sVEGFR-1 plays a role during melanoma progression.

METHODS

sVEGFR-1 expression was evaluated in a panel of 36 melanoma cell lines and 11 primary human melanocyte cultures by quantitative real-time polymerase chain reaction analysis and in specimens of primary or metastatic melanoma lesions from 23 patients by immunohistochemical analysis.

RESULTS

sVEGFR-1 expression was highly upregulated in melanoma cell lines with respect to human melanocytes. Interestingly, cell lines obtained from cutaneous metastases showed a significant reduction of sVEGFR-1 expression, as compared with cell lines derived from primary tumours. These results were confirmed by immunohistochemical analysis of sections from primary skin melanomas and the corresponding cutaneous metastases, suggesting that modulation of sVEGFR-1 expression influences ECM invasion by melanoma cells and metastasis localization. Moreover, we provide evidence that adhesion of melanoma cells to sVEGFR-1 is favoured by the activation of a VEGF-A/VEGFR-2 autocrine loop.

CONCLUSIONS

Our data strongly suggest that sVEGFR-1 plays a role in melanoma progression and that low sVEGFR-1/VEGF-A and sVEGFR-1/transmembrane VEGFR-1 ratios might predict a poor outcome in patients with melanoma.

Placenta growth factor in diabetic wound healing: altered expression and therapeutic potential

Reduced microcirculation and diminished expression of growth factors contribute to wound healing impairment in diabetes. Placenta growth factor (PlGF), an angiogenic mediator promoting pathophysiological neovascularization, is expressed during cutaneous wound healing and improves wound closure by enhancing angiogenesis. By using streptozotocin-induced diabetic mice, we here demonstrate that PlGF induction is strongly reduced in diabetic wounds. Diabetic transgenic mice overexpressing PlGF in the skin displayed accelerated wound closure compared with diabetic wild-type littermates. Moreover, diabetic wound treatment with an adenovirus vector expressing the human PlGF gene (AdCMV.PlGF) significantly accelerated the healing process compared with wounds treated with a control vector. The analysis of treated wounds showed that PlGF gene transfer improved granulation tissue formation, maturation, and vascularization, as well as monocytes/macrophages local recruitment. Platelet-derived growth factor, fibroblast growth factor-2, and vascular endothelial growth factor mRNA levels were increased in AdCMV.PlGF-treated wounds, possibly enhancing PlGF-mediated effects. Finally, PlGF treatment stimulated cultured dermal fibroblast migration, pointing to a direct role of PlGF in accelerating granulation tissue maturation. In conclusion, our data indicate that reduced PlGF expression contributes to impaired wound healing in diabetes and that PlGF gene transfer to diabetic wounds exerts therapeutic activity by promoting different aspects of the repair process.

Increased melanoma growth and metastasis spreading in mice overexpressing placenta growth factor

Placenta growth factor (PlGF), a member of the vascular endothelial growth factor family, plays an important role in adult pathological angiogenesis. To further investigate PlGF functions in tumor growth and metastasis formation, we used transgenic mice overexpressing PlGF in the skin under the control of the keratin 14 promoter. These animals showed a hypervascularized phenotype of the skin and increased levels of circulating PlGF with respect to their wild-type littermates. Transgenic mice and controls were inoculated intradermally with B16-BL6 melanoma cells. The tumor growth rate was fivefold increased in transgenic animals compared to wild-type mice, in the presence of a similar percentage of tumor necrotic tissue. Tumor vessel area was increased in transgenic mice as compared to controls. Augmented mobilization of endothelial and hematopoietic stem cells from the bone marrow was observed in transgenic animals, possibly contributing to tumor vascularization. The number and size of pulmonary metastases were significantly higher in transgenic mice compared to wild-type littermates. Finally, PlGF promoted tumor cell invasion of the extracellular matrix and increased the activity of selected matrix metalloproteinases. These findings indicate that PlGF, in addition to enhancing tumor angiogenesis and favoring tumor growth, may directly influence melanoma dissemination.

Granulocyte/macrophage colony-stimulating factor treatment of human chronic ulcers promotes angiogenesis associated with de novo vascular endothelial growth factor transcription in the ulcer bed

Summary Background Granulocyte/macrophage colony-stimulating factor (GM-CSF), a cytokine with pleiotropic functions, has been successfully employed in the treatment of chronic skin ulcers. The biological effects underlying GM-CSF action in impaired wound healing have been only partly clarified. Objectives To investigate the effects of GM-CSF treatment of chronic venous ulcers on lesion vascularization and on the local synthesis of the angiogenic factors vascular endothelial growth factor (VEGF) and placenta growth factor (PlGF). Methods Patients with nonhealing venous leg ulcers were treated with intradermal injection of recombinant human GM-CSF, and biopsies were taken at the ulcer margin before and 5 days after administration. Wound vascularization was analysed by immunohistochemistry using antiplatelet endothelial cell adhesion molecule-1/CD31 and anti-alpha-smooth muscle actin antibodies. VEGF and PlGF transcription was assessed by in situ hybridization. To identify the cell populations transcribing VEGF within the ulcer bed, the VEGF hybridization signal was correlated with the immunostaining for different cell type markers on serial sections. Direct induction of VEGF transcription by GM-CSF was investigated in GM-CSF-treated cultured macrophages and keratinocytes. Results Blood vessel density was significantly increased in the ulcer bed following GM-CSF treatment. VEGF transcripts were localized in keratinocytes at the ulcer margin both before and after GM-CSF treatment, whereas a VEGF hybridization signal was evident within the ulcer bed only following administration. PlGF mRNA was barely detectable in keratinocytes at the ulcer margin and was not visibly increased after treatment. Unlike VEGF, a specific PlGF hybridization signal could not be detected in cells within the ulcer following GM-CSF administration. Monocytes/macrophages were the main cell population transcribing VEGF after GM-CSF treatment. In vitro analysis demonstrated that VEGF transcription can be directly stimulated by GM-CSF in a differentiated monocytic cell line, but not in keratinocytes. Conclusions Our data show that increased vascularization is associated with GM-CSF treatment of chronic venous ulcers and indicate that inflammatory cell-derived VEGF may act as an angiogenic mediator of the healing effect of GM-CSF in chronic ulcers.

The placenta growth factor in skin angiogenesis

The placenta growth factor (PlGF) is a member of the vascular endothelial growth factor (VEGF) family that has been shown to play an important role in promoting adult pathological angiogenesis. Besides inducing its own signaling in endothelial cells, PlGF exerts its angiogenic action by synergising with VEGF. In the skin, PlGF expression is upregulated during wound healing and PlGF-deficient mice show delayed wound closure, indicating that this factor promotes angiogenesis during skin repair. Moreover, PlGF expression by melanoma cells has been linked to tumor growth. The analysis of a transgenic mouse model constitutively expressing high levels of PlGF in basal keratinocytes has shown that this factor has strong angiogenic properties in the skin during both embryonic and post-natal life. Furthermore, PlGF delivery to the skin via an adenoviral vector induces the formation of large and stable blood vessels, but contrary to VEGF application, does not affect lymphatic vessel functionality. Such evidence opens the possibility of employing PlGF for therapeutic modulation of skin angiogenesis.

Expression and function of neurotrophins and their receptors in cultured human keratinocytes

Whereas nerve growth factor has been extensively studied in human keratinocytes, little is known on the role of other members of the neurotrophin family. We investigated the expression and function of neurotrophins and neurotrophin receptors in cultured human keratinocytes. We demonstrated by reverse transcription-polymerase chain reaction that keratinocytes synthesize neurotrophin-3, brain-derived neurotrophic factor, and neurotrophin-4/5. These cells also express tyrosinase kinase A and C, the nerve growth factor and neuro-trophin-3 high-affinity receptors, respectively. On the other hand, only the truncated extracellular isoform of tyrosinase kinase B, the high-affinity brain-derived neurotrophic factor and neurotrophin-4/5 receptor, is detected in keratinocytes. Moreover, neurotrophin-3, brain-derived neurotrophic factor, and neurotrophin-4/5 proteins are secreted by human keratinocytes at low levels. Keratinocyte stem cells synthesize the highest amounts of nerve growth factor, while they secrete higher levels of nerve growth factor as compared with transit amplifying cells. Neurotrophin-3 stimulates keratinocyte proliferation, where brain-derived neurotrophic factor or neurotrophin-4/5 does not exert any effect on keratinocyte proliferation. Addition of neurotrophin-3 slightly upregulates the secretion of nerve growth factor, whereas nerve growth factor strongly augments neurotrophin-3 release. Ultraviolet B irradiation downregulates nerve growth factor, whereas it augments neurotrophin-3 and neurotrophin-4/5 protein levels. Ultraviolet A irradiation increases the level of neurotrophin-3, whereas it does not exert any effect on the other neurotrophins. Finally, neurotrophins other than nerve growth factor fail to protect human keratinocytes from ultraviolet B-induced apoptosis. This work delineates a functional neurotrophin network, which may contribute to epidermal homeostasis.

Vascular endothelial growth factor receptor-1 is deposited in the extracellular matrix by endothelial cells and is a ligand for the alpha 5 beta 1 integrin

Vascular endothelial growth factor receptor-1 (VEGFR-1) is a tyrosine kinase receptor for several growth factors of the VEGF family. Endothelial cells express a membrane-spanning form of VEGFR-1 and secrete a soluble variant of the receptor comprising only the extracellular region. The role of this variant has not yet been completely defined. In this study, we report that the secreted VEGFR-1 is present within the extracellular matrix deposited by endothelial cells in culture, suggesting a possible involvement in endothelial cell adhesion and migration. In adhesion assays, VEGFR-1 extracellular region specifically promoted endothelial cell attachment. VEGFR-1-mediated cell adhesion was divalent cation-dependent, and inhibited by antibodies directed against the alpha 5 beta 1 integrin. Moreover, VEGFR-1 promoted endothelial cell migration, and this effect was inhibited by anti-alpha 5 beta 1 antibodies. Direct binding of VEGFR-1 to the alpha 5 beta 1 integrin was also detected. Finally, binding to VEGFR-1 initiated endothelial cell spreading. Altogether these results indicate that the soluble VEGFR-1 secreted by endothelial cells becomes a matrix-associated protein that is able to interact with the alpha 5 beta 1 integrin, suggesting a new role of VEGFR-1 in angiogenesis, in addition to growth factor binding.

Binding properties, cell delivery, and gene transfer of adenoviral penton base displaying bacteriophage

The penton base of adenovirus mediates viral attachment to integrin receptors and particle internalisation, properties that can be exploited to reengineer prokaryotic viruses for the infection of mammalian cells. We report that filamentous phage displaying either the full-length penton base gene or a central region of 107 amino acids on their surface were able to bind, internalise, and transduce mammalian cells expressing integrin receptors. Both phage bound alphavbeta3, alphavbeta5, alpha3beta1, and alpha5beta1 integrin subtypes. Cell-binding was shown by electron microscopy; internalisation was investigated by immunofluorescence and confirmed by micropanning. As it has been described for adenovirus, pharmacologic disruption of phosphoinositide-30H kinase, but not of myosin light-chain kinase, inhibited phage internalisation. Recombinant phage encoding an eukaryotic expression cassette was able to mediate gene expression in mammalian cells. Taken together, these data open insights for the exploit of recombinant phage for integrin-targeted gene delivery.

Human melanoma cells secrete and respond to placenta growth factor and vascular endothelial growth factor

The vascular endothelial growth factor is produced by a large variety of human tumors, including melanoma, in which it appears to play an important role in the process of tumor-induced angiogenesis. Little information is available on the role of placenta growth factor, a member of the vascular endothelial growth factor family of cytokines, in tumor angiogenesis, even though placenta growth factor/vascular endothelial growth factor heterodimers have been recently isolated from tumor cells. To investigate the role of placenta growth factor and vascular endothelial growth factor homodimers and heterodimers in melanoma angiogenesis and growth, 19 human melanoma cell lines derived from primary or metastatic tumors were characterized for the expression of these cytokines and their receptors. Release of placenta growth factor and vascular endothelial growth factor polypeptides into the supernatant of human melanoma cells was demonstrated. Reverse transcriptase polymerase chain reaction analysis showed the presence of mRNAs encoding at least three different vascular endothelial growth factor isoforms (VEGF(121), VEGF(165), and VEGF(189)) and transcripts for two placenta growth factor isoforms (PlGF-1 and PlGF-2) in human melanoma cells. In addition, placenta growth factor expression in human melanoma in vivo was detected by immunohistochemical staining of tumor specimens. Both primary and metastatic melanoma cells were found to express the mRNAs encoding for vascular endothelial growth factor and placenta growth factor receptors (KDR, Flt-1, neuropilin-1, and neuropilin-2), and exposure of melanoma cells to these cytokines resulted in a specific proliferative response, supporting the hypothesis of a role of these angiogenic factors in melanoma growth. J Invest Dermatol 115:1000-1007 2000

Placenta growth factor is induced in human keratinocytes during wound healing

Placenta growth factor (PlGF) is a dimeric glycoprotein, structurally and functionally related to the vascular endothelial growth factor, a potent angiogenic/permeability factor known to play a role in the neoangiogenesis during wound repair. In this study we evaluated the expression of PlGF in human keratinocytes and investigated its possible role in wound healing. Northern blot analysis on cultured keratinocytes revealed a 1.7 kb mRNA transcript and reverse transcriptase-polymerase chain reaction allowed the detection of two PlGF isoforms generated by alternative RNA splicing. PlGF and vascular endothelial growth factor homodimers as well as vascular endothelial growth factor/PlGF heterodimers could be detected in keratinocyte conditioned medium. Increased expression of both PlGF mRNA and protein was observed upon treatment of keratinocytes with epidermal growth factor, transforming growth factor-alpha, transforming growth factor-beta, and interleukin-6, all cytokines present at the wound site during the early phase of repair. The analysis of human full-thickness healing wounds revealed appreciable levels of PlGF mRNA and protein in the migrating keratinocytes starting from day 3 after injury, and increasing at day 5. At day 7 PlGF mRNA was no longer detectable, while the protein was still expressed by migrating suprabasal keratinocytes. At day 13, when the wound had reepithelialized, PlGF immunostaining was completely negative. By in situ hybridization an intense signal for PlGF was also found on endothelial capillaries adjacent to the wound. These data demonstrate that keratinocytes are a source of PlGF during wound healing in vivo and indicate a role for this factor in the neoangiogenesis process associated with cutaneous wound repair.

Redesigning the substrate specificity of the hepatitis C virus NS3 protease

BACKGROUND

Hepatitis C Virus (HCV) non-structural protein 3 (NS3) encodes a trypsin-like serine protease that catalyzes the cleavages at the NS3/NS4A, NS4A/NS4B, NS4B/NS5A and NS5A/NS5B junctions in the viral polyprotein and that shows a preference for a cysteine as the P1 residue.

RESULTS

We describe here a partial model of the HCV NS3 protease which allowed us to predict the position of the secondary structure elements of the enzyme and of the residues involved in its specificity. By replacing these with the corresponding residues of Streptomyces griseus protease B1 we obtained a protease that, similar to the bacterial protein and unlike the wild-type enzyme, is able to cleave a substrate containing a phenylalanine in the P1 position.

CONCLUSIONS

These results confirm the reliability of our model and represent one of the few examples of redesign of a serine protease substrate specificity directed by molecular modelling.