Interleukin-7 (IL-7)-induced proliferation of CD8+ T-chronic lymphocytic leukemia cells

Genetically engineered mesenchymal stem cells: targeted delivery of immunomodulatory agents for tumor eradication

Cancer immunotherapy emerged as a novel therapeutic option that employs enhanced or amended native immune system to create a robust response against malignant cells. The systemic therapies with immune-stimulating cytokines have resulted in substantial dose-limiting toxicities. Targeted cytokine immunotherapy is being explored to overcome the heterogeneity of malignant cells and tumor cell defense with a remarkable reduction of systemic side effects. Cell-based strategies, such as dendritic cells (DCs), fibroblasts or mesenchymal stem cells (MSCs) seek to minimize the numerous toxic side effects of systemic administration of cytokines for extended periods of time. The usual toxicities comprised of a vascular leak, hypotension, and respiratory insufficiency. Natural and strong tropism of MSCs toward malignant cells made them an ideal systemic delivery vehicle to direct the proposed therapeutic genes to the vicinity of a tumor where their expression could evoke an immune reaction against the tumor. Compared with other methods, the delivery of cytokines via engineered MSCs is safer and renders a more practical, and promising strategy. Large numbers of genes code for cytokines have been utilized to reengineer MSCs as therapeutic cells. This review highlights the recent findings on the cytokine gene therapy for human malignancies by focusing on MSCs application in cancer immunotherapy.

IL-2, IL-7, and IL-15: Multistage regulators of CD4(+) T helper cell differentiation

Cytokines represent a class of environmental factors that are critical drivers of immune cell development. Cytokines of the common gamma-chain family, including interleukin (IL)-2, IL-7, and IL-15, have been the subject of intense experimental scrutiny and have well-defined roles as regulators of diverse immune cell types including CD4(+) T helper cells. Because of their pleiotropic effects on T-cell development and function, researchers and clinicians have attempted to harness the capabilities of these cytokines for therapeutic benefit. In this review, we summarize the recent progress in our understanding of the molecular mechanisms underlying the effects of these cytokines on CD4(+) T cell development and briefly discuss how these immunomodulatory cytokines are being used in efforts to treat human disease.

Potential implications of interleukin-7 in chronic wound healing

Methods of identifying chronic wounds that will heal in a timely, coordinated fashion and those that will not, together with novel therapeutic strategies, are vital for progression in the field of wound healing. Interleukin (IL)-7 has been associated with various biological and pathological processes. The present study explored the potential role of IL-7 in wound healing. IL-7 expression levels were examined in a clinical cohort of chronic wounds using reverse transcription-quantitative polymerase chain reaction and immunohistochemical staining analysis. The impact of recombinant human IL-7 (rhIL-7) on the growth and migrational rates of HaCaT keratinocyte cells was subsequently examined using in vitro growth and electric cell-substrate impedance sensing functional assays. The mRNA expression levels of IL-7 were increased in the healed chronic wound tissue samples, compared with non-healed chronic wound tissue samples, although the difference was not statistically significant. Similarly, immunohistochemical analysis revealed a greater staining intensity of IL-7 in the healed chronic wound tissue sections compared with the non-healed tissue sections. Treatment with rhIL-7 did not affect HaCaT cell growth rates, but was shown to enhance cell migration, an effect that could be further enhanced through the addition of inhibitors of neuronal Wiskott-Aldrich syndrome protein and protein kinase B. The data of the present study suggest that the expression levels of IL-7 may be increased in healing chronic wounds, and thus IL-7 may have a role in this process, potentially through its effects on the cellular migration of keratinocytes.

New insights of common gamma chain in hematological malignancies

The common gamma chain (γc) receptor family of cytokines including interleukin-2 (IL-2), IL-4, IL-7, IL-9, IL-15, and IL-21 has the common feature of sharing γc signaling subunit of their receptors. The γc cytokines have unique biological effects that regulate differentiation, survival and activation of multiple lymphocyte lineages and control proliferation of malignant cell by influencing tumor environment. It has been also described that different types of lymphoid leukemia and lymphoma exhibit expression of divergent γc cytokines and their receptors, as they may promote malignant transformation of lymphoid cells or on the contrary lead to tumor regression by inducing cell-cycle arrest. Therefore, cytokine-based or cytokine-directed blockade in cancer immunotherapy has currently revolutionized the development of cancer treatment. In this review, we will discuss about the role of γc cytokines and their signaling pathways in hematological malignancies and also propose a novel alternative approach that regulates γc cytokine responsiveness by γc in hematological malignancies.

Understanding the immunodeficiency in chronic lymphocytic leukemia: potential clinical implications

Chronic lymphocytic leukemia (CLL) is the most common leukemia in adults. Although significant advances have been made in the treatment of CLL in the last decade, it remains incurable. Treatments may be too toxic for some elderly patients, who constitute most of the individuals with this disease, and there remain subgroups of patients for which this therapy has minimal activity. This article summarizes the current understanding of the immune defects in CLL. It also examines the potential clinical implications of these findings.

Treatment with soluble interleukin-15Ralpha exacerbates intracellular parasitic infection by blocking the development of memory CD8+ T cell response

Interferon (IFN)-gamma-producing CD8+ T cells are important for the successful resolution of the obligate intracellular parasite Toxoplasma gondii by preventing the reactivation or controlling a repeat infection. Previous reports from our laboratory have shown that exogenous interleukin (IL)-15 treatment augments the CD8+ T cell response against the parasite. However, the role of endogenous IL-15 in the proliferation of activated/memory CD8+ T cells during toxoplasma or any other infection is unknown. In this study, we treated T. gondii immune mice with soluble IL-15 receptor alpha (sIL-15Ralpha) to block the host endogenous IL-15. The treatment markedly reduced the ability of the immune animals to control a lethal infection. CD8+ T cell activities in the sIL-15Ralpha-administered mice were severely reduced as determined by IFN-gamma release and target cell lysis assays. The loss of CD8+ T cell immunity due to sIL-15Ralpha treatment was further demonstrated by adoptive transfer experiments. Naive recipients transferred with CD44(hi) activated/memory CD8+ T cells and treated with sIL-15Ralpha failed to resist a lethal T. gondii infection. Moreover, sIL-15Ralpha treatment of the recipients blocked the ability of donor CD44(hi) activated/memory CD8+ T cells to replicate in response to T. gondii challenge. To our knowledge, this is the first demonstration of the important role of host IL-15 in the development of antigen-specific memory CD8+ T cells against an intracellular infection.

Extensive alternative splicing of interleukin-7 in malignant hematopoietic cells: implication of distinct isoforms in modulating IL-7 activity

Interleukin-7 (IL-7) plays a pivotal role in early stages of normal B and T cell development. In addition, IL-7 stimulates the proliferation of both antitumor reactive cells and a number of T and B cell malignancies, underlining its significance for leukemogenesis. However, its exact role in the process of pathologic maturation of lymphocytes and regulation of the immune response is not completely understood. As alternative splicing of pre-mRNA has been shown to be involved in the control of gene expression, and splicing-derived protein isoforms with antagonistic activity have been found, we assessed the mRNA-expression of IL-7 and its previously described alternative splice variant lacking exon 4, IL-7delta4, in leukemic cells from children with acute lymphoblastic leukemia (ALL). PCR of full-length IL-7 cDNA enabling the competitive amplification of both variants led to the amplification of diverse unexpected PCR products. The sequence data demonstrated the existence of three additional in-frame splice variants resulting from exon skipping of exon 3 or exon 5 or both in combination with exon 4. We named these IL-7delta3/4, IL-7delta4/5, and IL-7delta3/4/5. Furthermore, three out-of-frame splice variants were identified, IL-7(-56bpExon2), IL-7delta4(-56bpExon2), and IL-7delta3/4/5(-56bpExon2), in which, in addition to the aforementioned exon skipping, 56 bp of the 3' end of exon 2 are omitted. Our results led us to assume that splicing-derived IL-7 isoforms play a potential role in modulating IL-7-mediated biologic effects. Further studies are required to clarify the significance of the diverse IL-7 protein isoforms for the regulation of IL-7 function and the pathogenesis of leukemia.

Interleukin-7. Biology and implications for dermatology

In recent years, it has become apparent that IL-7, originally characterized as a growth factor for pre-B lymphocytes, also has important implications for the skin. Keratinocytes have been shown to produce IL-7. which in turn can elicit a variety of biological responses on several cell types residing in the skin. IL-7 has been demonstrated to augment the cytolytic activity of cytotoxic T cells (CTL) and natural killer (NK) cells against various neoplastic targets including melanoma cells. Proliferation and long-term survival of murine dendritic epidermal T lymphocytes (DETC) in vitro is supported by IL-7. IL-7 also induces secretion of inflammatory cytokines by monocytes/macrophages and renders these cells to become tumoricidal against melanoma cells. Normal and malignant melanocytes respond to IL-7 with increased expression of intercellular adhesion molecule (ICAM-1). In addition, IL-7 has been shown to act as growth factor for Sezary cells, suggesting a role of keratinocyte-derived IL-7 in the pathogenesis of cutaneous T cell lymphoma. Because of the potent in vitro immunomodulatory effects of IL-7 which have been confirmed in mouse tumor models, IL-7 may become a valuable additional agent to immunotherapeutical regimens currently studied in patients with advanced melanoma. This review summarizes our present knowledge about the molecular and immunological properties of IL7 with emphasis on the effects of that cytokine within the cutaneous compartment and the potential clinical utility in dermatology.

The synergistic effects of interleukin 2 and interleukin 7 on the proliferation and autologous tumor cell lysis of tumor-associated lymphocytes

Interleukin-7 (IL-7) has an ability to stimulate the proliferation of pre-B cells. It has been shown that IL-7 can also activate T lymphocytes. We here demonstrate that IL-7 in combination with interleukin-2 (IL-2) can drive cell proliferation and enhance the autologous tumor cell lysis by peripheral blood mononuclear cells (PBMC) and autologous mixed lymphocyte tumor cell culture (MLTC)-derived effector cells (MLTC cells). These synergistic effects of IL-2 and IL-7 on the proliferation and the augmentation of autologous tumor cell lysis were found for both effector cells. These effects were inhibited by neutralizing antibodies to IL-2 or IL-7, and by a combination of both antibodies, significantly. In terms of phenotypical expression, CD3 positive cells comprised the vast majority of MLTC cells after culture in medium containing IL-2 and IL-7 with an increase of IL-2 receptor positive cells.