Infectious Tolerance: Human CD25+ Regulatory T Cells Convey Suppressor Activity to Conventional CD4+ T Helper Cells

Regulatory CD4+CD25+ T cells (Treg) are mandatory for maintaining immunologic self-tolerance. We demonstrate that the cell-cell contact–mediated suppression of conventional CD4+ T cells by human CD25+ Treg cells is fixation resistant, independent from membrane-bound TGF-β but requires activation and protein synthesis of CD25+ Treg cells. Coactivation of CD25+ Treg cells with Treg cell–depleted CD4+ T cells results in anergized CD4+ T cells that in turn inhibit the activation of conventional, freshly isolated CD4+ T helper (Th) cells. This infectious suppressive activity, transferred from CD25+ Treg cells via cell contact, is cell contact–independent and partially mediated by soluble transforming growth factor (TGF)-β. The induction of suppressive properties in conventional CD4+ Th cells represents a mechanism underlying the phenomenon of infectious tolerance. This explains previously published conflicting data on the role of TGF-β in CD25+ Treg cell–induced immunosuppression

RASSF10 Promoter Hypermethylation Is Frequent in Malignant Melanoma of the Skin but Uncommon in Nevus Cell Nevi

The Ras association domain family (RASSF) consists of several tumor suppressor genes, which are frequently silenced in human cancers. We analyzed the epigenetic inactivation of RASSF2 and RASSF10 in malignant melanoma (MM) of the skin, including 5 MM cell lines, 28 primary MM, 33 metastases of MM, 47 nevus cell nevi (NCN), and 22 control tissues. The RASSF2 promoter was epigenetically downregulated in two MM cell lines only, but not in any of the investigated tumor samples. In contrast, hypermethylation of the RASSF10 promoter was found in all investigated cell lines, 19/28 (68%) of the primary MM and 30/33 (91%) of the MM metastases, 2/18 (11%) of the dysplastic NCN, and 0/29 (0%) of the non-dysplastic NCN (difference between MM and all nevi, P<0.001). RASSF10 promoter hypermethylation correlated with a reduced RASSF10 mRNA expression in 3/4 MM cell lines, and treatment with a DNA methylation inhibitor reactivated RASSF10 transcription. Furthermore, immunohistological RASSF10 expression corresponds negatively to its promoter methylation state. In summary, RASSF10 proved to be a characteristically epigenetically silenced tumor suppressor in melanomagenesis, and analysis of RASSF10 methylation status represents a new candidate tool to assist in discrimination between MM and NCN

Regulatory T cell-deficient scurfy mice develop systemic autoimmune features resembling lupus-like disease

Introduction: Scurfy mice are deficient in regulatory T cells (Tregs), develop a severe, generalized autoimmune disorder that can affect almost every organ and die at an early age. Some of these manifestations resemble those found in systemic lupus erythematosus (SLE). In addition, active SLE is associated with low Treg numbers and reduced Treg function, but direct evidence for a central role of Treg malfunction in the pathophysiology of lupus-like manifestations is still missing. In the present study, we characterize the multiorgan pathology, autoantibody profile and blood count abnormalities in scurfy mice and show their close resemblances to lupus-like disease. Methods: Scurfy mice have dysfunctional Tregs due to a genetic defect in the transcription factor Forkhead box protein 3 (Foxp3). We analyzed skin, joints, lung and kidneys of scurfy mice and wild-type (WT) controls by conventional histology and immunofluorescence (IF) performed hematological workups and tested for autoantibodies by IF, immunoblotting and enzyme-linked immunosorbent assay. We also analyzed the intestines, liver, spleen and heart, but did not analyze all organs known to be affected in scurfy mice (such as the testicle, the accessory reproductive structures, the pancreas or the eyes). We transferred CD4+ T cells of scurfy or WT mice into T cell-deficient B6/nude mice. Results: We confirm previous reports that scurfy mice spontaneously develop severe pneumonitis and hematological abnormalities similar to those in SLE. We show that scurfy mice (but not controls) exhibited additional features of SLE: severe interface dermatitis, arthritis, mesangioproliferative glomerulonephritis and high titers of anti-nuclear antibodies, anti-double-stranded DNA antibodies, anti-histone antibodies and anti-Smith antibodies. Transfer of scurfy CD4+ T cells (but not of WT cells) induced autoantibodies and inflammation of lung, skin and kidneys in T cell-deficient B6/nude mice. Conclusion: Our observations support the hypothesis that lupus-like autoimmune features develop in the absence of functional Tregs

Modulation of Contact Sensitivity Responses by Bacterial Superantigen

Superantigens are potent modulators of the immune system, especially T cells. Therefore, we determined the influence of superantigens on the T-cell-mediated immune response, contact sensitivity. We chose the combination of staphylococcal enterotoxin B (SEB) as superantigen and 2,4-dinitrofluorbenzene (DNFB) as the contact sensitizer, because in BALB/c mice SEB reacts almost exclusively with Vβ8+ T cells, and these cells are capable of transferring contact sensitivity to DNFB from sensitized donors to naive syngeneic recipients. Pretreatment with a single intradermal injection of 50 ng SEB 24 h before DNFB exposure at the same site on the lower abdomen enhanced the induction of contact sensitivity: its intradermal injection permitted sensitization with non-sensitizing concentrations of DNFB as assessed by ear swelling responses after challenge with DNFR. In contrast, pretreatment with repeated intradermal injections of 50 ng SEB every other day over at least 1 week inhibited the induction of contact sensitivity following sensitization. The enhancing effect of SEB may be explained by the creation of a proinflammatory milieu in the skin after a single intradermal injection of the bacterial toxin, whereas the inhibitory effect may be due to tolerization of Vβ8+ T cells. The data indicate that products of skin-colonizing bacteria that can serve as superantigens are able to augment or inhibit the development of contact sensitivity

Tolerability of BRAF and MEK Inhibitors for Metastasized Melanoma after Intra-Class Switch: A Multicenter, Retrospective Study

Simple Summary Patients suffering from metastasized melanoma can be treated with three different combinations of tablets (“targeted therapy”), with similar efficacy but different side effect profiles. When one of the combinations is not tolerated well, their physicians may switch to a different combination; however, it has not been evaluated whether the second combination is actually tolerated better. In this work, we collected data on 94 patients from six German cancer centers who received two different combinations of targeted melanoma therapy to figure out whether the second combination was tolerated better. We found that indeed many side effects did not occur again and the novel combination was overall tolerated better, which justifies switching the combination when a patient experiences severe side effects. However, new side effects may occur. We believe our results are important for oncologists to adequately counsel patients with poor tolerability of this commonly used melanoma treatment. Abstract Targeted therapy with BRAF and MEK inhibitors (BRAFi, MEKi) is one of the mainstays of melanoma treatment. When dose-limiting toxicity (DLT) is observed, an option represents the intra-class switch to a different BRAFi+MEKi combination. Currently, there is scarce evidence for this procedure. This is a multicenter, retrospective analysis from six German skin cancer centers of patients who received two different combinations of BRAFi and MEKi. In total, 94 patients were included: 38 patients (40%) were re-exposed with a different combination because of previous unacceptable toxicity, 51 (54%) were re-exposed after progression, and 5 (5%) were included for other reasons. Of the 44 patients with a DLT during their first BRAFi+MEKi combination, only five (11%) experienced the same DLT during their second combination. A new DLT was experienced by 13 patients (30%). Six patients (14%) had to discontinue the second BRAFi treatment due to its toxicity. Compound-specific adverse events were avoided in the majority of patients by switching to a different combination. Efficacy data were similar to historical cohorts of BRAFi+MEKi rechallenge, with an overall response rate of 31% for patients who had previously progressed to treatment. We conclude that switching to a different BRAFi+MEKi combination if dose-limiting toxicity occurs is a feasible and rational approach in patients with metastatic melanoma

Scurfy Mice Develop Features of Connective Tissue Disease Overlap Syndrome and Mixed Connective Tissue Disease in the Absence of Regulatory T Cells

Due to a missense mutation in the Foxp3 gene, scurfy mice are deficient in functional regulatory T cells (Treg). The consequent loss of peripheral tolerance manifests itself by fatal autoimmune mediated multi-organ disease. Previous studies have outlined the systemic inflammatory disease and demonstrated production of anti-nuclear antibodies (ANA) in scurfy mice. However, specific autoantibody targets remained to be defined. ANA are immunological markers for several connective tissue diseases (CTD) and target a large number of intracellular molecules. Therefore, we examined scurfy sera for the presence of different ANA specificities and further assessed the organ involvement in these animals. Indirect immunofluorescence was used as a screen for ANA in the sera of scurfy mice and dilutions of 1/100 were considered positive. Addressable laser bead immunoassays (ALBIA) were used to detect specific autoantibody targets. Subsequent histological tissue evaluation was verified by hematoxylin and eosin (H&amp;E) staining. In our study, we observed that nearly all scurfy mice produced ANA. The most prevalent pattern in scurfy sera was nuclear coarse speckled, also known as the AC-5 pattern according to the International Consensus on ANA Patterns. U1-ribonucleoprotein (U1RNP) was found to be the most common target antigen recognized by autoantibodies in scurfy mice. Additionally, scurfy mice exhibited a mild myositis with histological characteristics similar to polymyositis/dermatomyositis. Myopathy-specific autoantibody profile revealed significantly increased levels of anti-SMN (survival of motor neuron) as well as anti-Gemin3 antibodies in scurfy sera. Overall, we demonstrate that the impaired peripheral tolerance in the absence of regulatory T cells in scurfy mice is associated with features of mixed connective tissue disease (MCTD). This includes, along with our previous findings, very high titers of anti-U1RNP antibodies and an inflammatory myopathy

Skin Cancer Classification Using Convolutional Neural Networks: Systematic Review

Background: State-of-the-art classifiers based on convolutional neural networks (CNNs) were shown to classify images of skin cancer on par with dermatologists and could enable lifesaving and fast diagnoses, even outside the hospital via installation of apps on mobile devices. To our knowledge, at present there is no review of the current work in this research area. Objective: This study presents the first systematic review of the state-of-the-art research on classifying skin lesions with CNNs. We limit our review to skin lesion classifiers. In particular, methods that apply a CNN only for segmentation or for the classification of dermoscopic patterns are not considered here. Furthermore, this study discusses why the comparability of the presented procedures is very difficult and which challenges must be addressed in the future. Methods: We searched the Google Scholar, PubMed, Medline, ScienceDirect, and Web of Science databases for systematic reviews and original research articles published in English. Only papers that reported sufficient scientific proceedings are included in this review. Results: We found 13 papers that classified skin lesions using CNNs. In principle, classification methods can be differentiated according to three principles. Approaches that use a CNN already trained by means of another large dataset and then optimize its parameters to the classification of skin lesions are the most common ones used and they display the best performance with the currently available limited datasets. Conclusions: CNNs display a high performance as state-of-the-art skin lesion classifiers. Unfortunately, it is difficult to compare different classification methods because some approaches use nonpublic datasets for training and/or testing, thereby making reproducibility difficult. Future publications should use publicly available benchmarks and fully disclose methods used for training to allow comparability

Teledermatology: Comparison of Store-and-Forward Versus Live Interactive Video Conferencing

A decreasing number of dermatologists and an increasing number of patients in Western countries have led to a relative lack of clinicians providing expert dermatologic care. This, in turn, has prolonged wait times for patients to be examined, putting them at risk. Store-and-forward teledermatology improves patient access to dermatologists through asynchronous consultations, reducing wait times to obtain a consultation. However, live video conferencing as a synchronous service is also frequently used by practitioners because it allows immediate interaction between patient and physician. This raises the question of which of the two approaches is superior in terms of quality of care and convenience. There are pros and cons for each in terms of technical requirements and features. This viewpoint compares the two techniques based on a literature review and a clinical perspective to help dermatologists assess the value of teledermatology and determine which techniques would be valuable in their practice