Staphylococcus aureus and its toxins have been linked to disease progression and mortality in advanced stages of cutaneous T-cell lymphoma (CTCL). CD8
+
T cells play a crucial role in anti-cancer ...responses and high CD8
+
T cell numbers in tumor lesions are associated with a favorable prognosis in CTCL. Here, we show that CD8
+
T cells from both healthy donors and Sézary syndrome patients are highly susceptible to cell death induced by Staphylococcal alpha-toxin, whereas malignant T cells are not. Importantly, alpha-toxin almost completely blocks cytotoxic killing of CTCL tumor cells by peptide-specific CD8
+
T cells, leading to their escape from induced cell death and continued proliferation. These findings suggest that alpha-toxin may favor the persistence of malignant CTCL cells in vivo by inhibiting CD8
+
T cell cytotoxicity. Thus, we propose a novel mechanism by which colonization with Staphylococcus aureus may contribute to cancer immune evasion and disease progression in CTCL.
Staphylococcus aureus is implicated in disease progression in cutaneous T-cell lymphoma (CTCL). Here, we demonstrate that malignant T cell lines derived from CTCL patients as well as primary ...malignant CD4
+
T cells from Sézary syndrome patients are considerably more resistant to alpha-toxin-induced cell death than their non-malignant counterparts. Thus, in a subset of Sézary syndrome patients the ratio between malignant and non-malignant CD4
+
T cells increases significantly following exposure to alpha-toxin. Whereas toxin-induced cell death is ADAM10 dependent in healthy CD4
+
T cells, resistance to alpha-toxin in malignant T cells involves both downregulation of ADAM10 as well as other resistance mechanisms. In conclusion, we provide first evidence that Staphylococcus aureus derived alpha-toxin can tilt the balance between malignant and non-malignant CD4
+
T cells in CTCL patients. Consequently, alpha-toxin may promote disease progression through positive selection of malignant CD4
+
T cells, identifying alpha-toxin as a putative drug target in CTCL.
A variety of tumors are potentially immunogenic but do not stimulate an effective antitumor immune response in vivo. Tumors may be capable of delivering antigen-specific signals to T cells, but may ...not deliver the costimulatory signals necessary for full activation of T cells. In this regard, we recently reported that a human melanoma cell line (sMC) expressing MHC class II, was able to induce clonal anergy in a specific, MHC-restricted CD-4+ T cell clone (sTC3). We used this system to investigate the influence of interleukin (IL)-12 on induction of this T cell unresponsiveness. The presence of 10 to 100 U IL-12 during the induction phase of anergy leads to a primary proliferative response of sTC3, which was significantly higher than that induced by IL-12 alone; however, in the absence of IL-12 no proliferation was seen during the induction of anergy. Subsequent optimal stimulation of IL-12 treated cells, but not of those cultured without IL-12, led to substantial IL-2 production and cell proliferation. This indicates that induction of the unresponsive state could be inhibited by IL-12. In addition, we have recently demonstrated that anergic T cell clones can produce high amounts of IL-10 and that this event was correlated with their impaired ability to produce IL-2. This marked induction of IL-10 can be suppressed if IL-12 is present during initiation of unresponsiveness. However, IL-12 was not able to prime the T cell clone, sTC3, to become resistant against the anergizing stimulus, as this cytokine was only effective when present at the time of anergy induction.
Most of our knowledge on human CNS circuitry and related disorders originates from model organisms. How well such data translate to the human CNS remains largely to be determined. Human brain slice ...cultures derived from neurosurgical resections may offer novel avenues to approach this translational gap. We now demonstrate robust preservation of the complex neuronal cytoarchitecture and electrophysiological properties of human pyramidal neurons in long-term brain slice cultures. Further experiments delineate the optimal conditions for efficient viral transduction of cultures, enabling 'high throughput' fluorescence-mediated 3D reconstruction of genetically targeted neurons at comparable quality to state-of-the-art biocytin fillings, and demonstrate feasibility of long term live cell imaging of human cells
. This model system has implications toward a broad spectrum of translational studies, regarding the validation of data obtained in non-human model systems, for therapeutic screening and genetic dissection of human CNS circuitry.
Classical paraneoplastic encephalitis syndromes with 'onconeural' antibodies directed to intracellular antigens, and the recently described paraneoplastic or non-paraneoplastic encephalitides and ...antibodies against both neural surface antigens (voltage-gated potassium channel-complexes, N-methyl-d-aspartate receptors) and intracellular antigens (glutamic acid decarboxylase-65), constitute an increasingly recognized group of immune-mediated brain diseases. Evidence for specific immune mechanisms, however, is scarce. Here, we report qualitative and quantitative immunopathology in brain tissue (biopsy or autopsy material) of 17 cases with encephalitis and antibodies to either intracellular (Hu, Ma2, glutamic acid decarboxylase) or surface antigenic targets (voltage-gated potassium channel-complex or N-methyl-d-aspartate receptors). We hypothesized that the encephalitides with antibodies against intracellular antigens (intracellular antigen-onconeural and intracellular antigen-glutamic acid decarboxylase groups) would show neurodegeneration mediated by T cell cytotoxicity and the encephalitides with antibodies against surface antigens would be antibody-mediated and would show less T cell involvement. We found a higher CD8/CD3 ratio and more frequent appositions of granzyme-B(+) cytotoxic T cells to neurons, with associated neuronal loss, in the intracellular antigen-onconeural group (anti-Hu and anti-Ma2 cases) compared to the patients with surface antigens (anti-N-methyl-d-aspartate receptors and anti-voltage-gated potassium channel complex cases). One of the glutamic acid decarboxylase antibody encephalitis cases (intracellular antigen-glutamic acid decarboxylase group) showed multiple appositions of GrB-positive T cells to neurons. Generally, however, the glutamic acid decarboxylase antibody cases showed less intense inflammation and also had relatively low CD8/CD3 ratios compared with the intracellular antigen-onconeural cases. Conversely, we found complement C9neo deposition on neurons associated with acute neuronal cell death in the surface antigen group only, specifically in the voltage-gated potassium channel-complex antibody patients. N-methyl-d-aspartate receptors-antibody cases showed no evidence of antibody and complement-mediated tissue injury and were distinguished from all other encephalitides by the absence of clear neuronal pathology and a low density of inflammatory cells. Although tissue samples varied in location and in the stage of disease, our findings strongly support a central role for T cell-mediated neuronal cytotoxicity in encephalitides with antibodies against intracellular antigens. In voltage-gated potassium channel-complex encephalitis, a subset of the surface antigen antibody encephalitides, an antibody- and complement-mediated immune response appears to be responsible for neuronal loss and cerebral atrophy; the apparent absence of these mechanisms in N-methyl-d-aspartate receptors antibody encephalitis is intriguing and requires further study.
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