Failure Of Immunosurveillance Research Articles

In vivo hematopoietic Myc activation directs a transcriptional signature in endothelial cells within the bone marrow microenvironment.

Cancer pathogenesis involves tumor-intrinsic genomic aberrations and tumor-cell extrinsic mechanisms such as failure of immunosurveillance and structural and functional changes in the microenvironment. Using Myc as a model oncogene we established a conditional mouse bone marrow transduction/transplantation model where the conditional activation of the oncoprotein Myc expressed in the hematopoietic system could be assessed for influencing the host microenvironment. Constitutive ectopic expression of Myc resulted in rapid onset of a lethal myeloproliferative disorder with a median survival of 21 days. In contrast, brief 4-day Myc activation by means of the estrogen receptor (ER) agonist tamoxifen did not result in gross changes in the percentage/frequency of hematopoietic lineages or hematopoietic stem/ progenitor cell (HSPC) subsets, nor did Myc activation significantly change the composition of the non-hematopoietic microenvironment defined by phenotyping for CD31, ALCAM, and Sca-1 expression. Transcriptome analysis of endothelial CD45- Ter119- cells from tamoxifen-treated MycER bone marrow graft recipients revealed a gene expression signature characterized by specific changes in the Rho subfamily pathway members, in the transcription-translation-machinery and in angiogenesis. In conclusion, intra-hematopoietic Myc activation results in significant transcriptome alterations that can be attributed to oncogene-induced signals from hematopoietic cells towards the microenvironment, e. g. endothelial cells, supporting the idea that even pre-leukemic HSPC highjack components of the niche which then could protect and support the cancer-initiating population.

A decrease of regulatory T cells and altered expression of NK receptors are observed in subacute sclerosing panencephalitis.

Subacute sclerosing panencephalitis (SSPE) is caused by a persistent measles virus infection. Regulatory mechanisms can be responsible for a failure of immunosurveillance in children with SSPE. In this study, peripheral blood cells of 71 patients with SSPE and 57 children with other diseases were compared phenotypically. The proportions of CD4(+), CD8(+) T, and NK cells were homogenous, whereas total CD3(+) T and Treg (CD4(+)CD25(+)CD152(+)) cells were decreased in patients with SSPE. The proportion of CD8(+) T cells expressing the inhibitory NKG2A(+) receptor was also decreased (1.7% ± 1.7% vs. 2.6% ± 1.9%, p = 0.007) in patients with SSPE, whereas the proportion of NK cells expressing activating NKG2C was increased compared with the control group (30.0% ± 17.3% vs. 22.2% ± 17.0%, p = 0.039). The decrease in the number of cells with regulatory phenotype, the lower presence of the inhibitory NK receptors on CD8(+) cells, and higher activating NK receptors on NK cells in SSPE indicate an upregulation of these cell types that favors their response. This state of active immune response may be caused by chronic stimulation of viral antigens leading to altered regulatory pathways.

Depletion of stromal cells expressing fibroblast activation protein-α from skeletal muscle and bone marrow results in cachexia and anemia

Fibroblast activation protein-α (FAP) identifies stromal cells of mesenchymal origin in human cancers and chronic inflammatory lesions. In mouse models of cancer, they have been shown to be immune suppressive, but studies of their occurrence and function in normal tissues have been limited. With a transgenic mouse line permitting the bioluminescent imaging of FAP(+) cells, we find that they reside in most tissues of the adult mouse. FAP(+) cells from three sites, skeletal muscle, adipose tissue, and pancreas, have highly similar transcriptomes, suggesting a shared lineage. FAP(+) cells of skeletal muscle are the major local source of follistatin, and in bone marrow they express Cxcl12 and KitL. Experimental ablation of these cells causes loss of muscle mass and a reduction of B-lymphopoiesis and erythropoiesis, revealing their essential functions in maintaining normal muscle mass and hematopoiesis, respectively. Remarkably, these cells are altered at these sites in transplantable and spontaneous mouse models of cancer-induced cachexia and anemia. Thus, the FAP(+) stromal cell may have roles in two adverse consequences of cancer: their acquisition by tumors may cause failure of immunosurveillance, and their alteration in normal tissues contributes to the paraneoplastic syndromes of cachexia and anemia.

Abstract IA27: The FAP+ stromal cell and escape from immunosurveillance

Abstract IA27: The FAP+ stromal cell and escape from immunosurveillance

Severe Myelosuppression and MRSA Infection as the Presentation of Perinatal HIV Infection

Severe Myelosuppression and MRSA Infection as the Presentation of Perinatal HIV Infection

In situ analysis of the antigen-processing machinery in acute myeloid leukaemic blasts by tissue microarray

Altered expression of major histocompatibility complex (MHC) class I molecules can be caused by defects in genes of the antigen-processing machinery (APM), and is often correlated to progression in solid tumours. However, little is known about expression of the APM components in blasts from patients with acute myeloid leukaemia (AML). In this study, we investigated the expression of the APM components large multifunctional peptidases (LMP) 2 and 7, transporter-associated with antigen processing (TAP) 1 and 2, beta-2-microglobulin (beta2m) and MHC class I heavy chain in situ by tissue microarray from bone marrow biopsies of 30 AML patients. APM components were heterogeneously expressed in all AML samples tested, but no significant correlation with the AML subtype according to the French-American-British classification was found. Depending on the APM component tested, up to 90% of the trephines showed no or weak expression, whereas the LMP7 protein was detected in 66% of all samples. By following disease progression in individual AML patients, we found severe downregulation of APM components in two out of four patients from initial diagnosis to relapse. We conclude that downregulation of APM components may play a role in the failure of immuno-surveillance and may therefore contribute to relapse in acute leukaemia.

Immunosurveillance of pancreatic adenocarcinoma: Insights from genetically engineered mouse models of cancer

The resurgent theory of cancer immunosurveillance holds that the immune system plays an important role in the suppression of tumors, particularly in the elimination of early neoplastic lesions. Tumors with reduced immunogenicity or those that have acquired mechanisms to suppress immune effector functions, however, can emerge from this selection pressure and grow progressively. This is an especially important issue in pancreatic cancer, which although inflammatory in vivo is nevertheless highly aggressive and nearly always lethal. Here, we review emerging data obtained from novel genetically defined mouse models of pancreatic adenocarcinoma that suggest that the immune system may be complicit in the inception and progression of pancreatic cancer. Host immune cells with suppressive properties infiltrate the pancreas early during tumorigenesis, even at the earliest stages of neoplasia, preceding and effectively undermining any lymphocytes with potential antitumor function. Thus, in pancreatic adenocarcinoma, the failure of immunosurveillance is likely an early event during tumorigenesis, a concept that carries important implications for the design of novel immunotherapeutics in this disease.

Multiple basal cell carcinoma in lymphoedema

SummaryBasal cell carcinoma is the most common malignant skin tumour, but rarely appears in more than one location. For these multiple basal cell carcinoma (MBCC), lymphoedema seems to be a predisposing factor. We report the case of a patient with secondary lymphoedema, presenting with a 3-year-history of ulcerations and papules on her lymphoedematous leg. Histology confirmed the clinical diagnosis of MBCC in all lesions.Pathophysiologically, a strong risk factor for the development of MBCC in lymphoedema seems to be the local failure of immunosurveillance. In obstructive lymphoedema, an impairment of lymphocyte and Langerhans cell trafficking was observed, resulting in ineffective phagocytosis of foreign antigens. Consequently, lymphoedema is an immunologically vulnerable area, facilitating the development of MBCC. Nevertheless, other risk factors such as actinic skin damage and somatic mutations might also play a role in the development of MBCC in lymphoedema. Despite its rare occurrence, MBCC has to be taken into consideration in all suspicious skin lesions. Whenever in doubt, skin biopsy should be performed.

Immunological surveillance against neoplasia: An immunological quandary

Immunological endéavor in recent years calls for a reappraisal of the concept of immunosurveillance against neoplasia. This concept proposes an immunological policing system capable of aborting tumor growth by the recognition of “nonself” tumor associated antigens on neoplastic cells. The model is supported by evidence of tumor induction in the immunosuppressed host and the demonstration of an immune response to tumors in animals. The occurrence of tumor, regarded as a failure of immunosurveillance, is attributed to selection of neoplastic cells for immunological or other reasons or abnormal humoral or cellular antitumor immune responses. However protagonists of the postulate are faced with mounting evidence that fails to support the surveillance hypothesis. These observations include, inter alia, the monoclonality of certain tumors, the low incidence of spontaneous tumors in genetically immunodeficient mice and immunological privileged sites, and new ideas about the pathogenesis of lymphoproliferative neoplasms. However, contradictory arguments are not sufficiently substantiated to prosecute the case against surveillance conclusively. In citing highlights of the evolving quandary, both the pros and cons of immunological surveillance are presented here.

Failure of immunosurveillance against chemically induced in situ tumors in mice.

Failure of immunosurveillance against chemically induced in situ tumors in mice.