Praveen Deepak

IL-13 Neutralization Modulates Function of Type II Polarized Macrophages in vivo in a Murine T-Cell Lymphoma

IL-13 is a Th2 cytokine that suppresses the effector function and alters the phenotype and function of macrophages switching to alternatively activated or type II polarized macrophages. The type II polarized macrophages or M2 phenotype differ from normal macrophages greatly in terms of receptor expression, cytokine and NO production, that show tumor promoting function rather than tumoricidal function of classically activated macrophages. The chemokines CCL-22 and CCL-17 produced by either tumor cells or alternatively activated macrophages attract Th2 cells preferentially, which increase the local concentration of Th2 cytokines including IL-13 that further skewed the normal phenotype of macrophages at the site of the tumor micro-environment. Therefore, it is possible to restore the phenotype and function of alternatively activated macrophages by eliminating or blocking the activities of these cytokines. In the present investigation, we show that by blocking the activity/signaling of one of its major constituents IL-13, the iNOS expression and correspondingly NO production increases. The observation signifies its efficacy towards a novel approach for cancer therapy by modulating the function of tumor-associated macrophages (TAM) in vivo for the first time.

IL-13 from Th2-type cells suppresses induction of antigen-specific Th1 immunity in a T-cell lymphoma

Daltons lymphoma (DL) is a transplantable T-cell lymphoma of spontaneous origin, characterized by highly invasive and immunosuppressive property. Progression of DL cells results into an imbalance of T helper type 1 (T(h)1)/T helper type 2 (T(h)2)-type cytokine in the host, which is partly responsible for DL-induced severe immunosuppression and DL cell progression. In this study, we have shown the role of IL-13 in the regulation of T(h)1 immunity in both normal healthy and DL-bearing host. IL-13 pre-treatment inhibits the induction of 2,4-dinitro-1-fluorobenzene-induced contact hypersensitivity and delayed-type hypersensitivity (DTH) in antigen-challenged mice, which have been confirmed by neutralizing IL-13 by systemic delivery of non-signaling decoy receptor IL-13Ralpha2. Furthermore, IL-13 neutralization enhances the splenocyte proliferation, which has been inhibited by IL-13 administration. Adoptive transfer of splenocyte from IL-13-pre-treated mice and macrophages incubated with IL-13 and pulsed with antigens suppresses the DTH as well in antigen-challenged recipient mice. In addition, it also suppresses the production of pro-inflammatory cytokine and C-C chemokine in DTH footpad. Furthermore, IL-13 neutralization not only enhances the DTH reaction but also increases longevity and survival of DL-bearing host, which suggests that blocking/inactivating systemic IL-13 enhances T(h)1 immunity, and therefore, effects to diminish IL-13 production may have therapeutic value in a host bearing T-cell lymphoma.

Interleukin-13-induced type II polarization of inflammatory macrophages is mediated through suppression of nuclear factor-κB and preservation of IκBα in a T cell lymphoma

The article from Clinical & Experimental Immunology, ‘Interleukin‐13‐induced type II polarization of inflammatory macrophages is mediated through suppression of nuclear factor‐κB and preservation of IκBα in a T cell lymphoma’, by P. Deepak, S. Kumar and A. Acharya (August 2007, 149(2), 378–386), published online on 5th June 2007] on Wiley InterScience (http://www.interscience.wiley.com), has been retracted by agreement between the Editor‐in‐Chief of Clinical & Experimental Immunology and Wiley‐Blackwell.

A benzophenanthridine alkaloid, chelerythrine induces apoptosis in vitro in a Dalton's lymphoma

PURPOSE The aim of this study was to investigate the effect of chelerythrine on DL cell apoptosis in an in vitro experimental setup. MATERIALS AND METHODS For tumor model, spontaneous occurring T-cell lymphoma designated as Daltons lymphoma (DL) was selected. Double staining, transmission electron microscope (TEM), fluorescence microscopy, Western blotting, Reverse Transcriptase-Polymerase Chain Reaction, and DNA fragmentation assay were used to detect heat shock factor 1 (HSF1) and hsp70 expression and PKC phosphorylation, and apoptotic characteristic of DL cells. RESULTS Chelerythrine exposure resulted in significant morphological alteration comparable to that of apoptosis. Furthermore, it was confirmed by fluorescence microscopy, TEM analysis, and DNA fragmentation assay that 10 μg/mL of chelerythrine is capable of inducing apoptosis in DL cells. The suppression in HSF1 expression and subsequent inhibition of hsp70 expression in chelerythrine-treated DL cells suggest that chelerythrine induces apoptosis in DL cells by inhibiting the expression of these cytoprotective proteins. CONCLUSION Chelerythrine is capable of inducing apoptosis DL cells in vitro and therefore, it could be useful in combating tumor growth and progression.

Progressive growth of a murine T cell lymphoma alters population kinetics and cell viability of macrophages in a tumor-bearing host

Tumor progression induces infiltration of immune cell populations at the site of tumor growth. Infiltrated leukocyte population including monocyte and macrophages interacts with tumor cells and tumor microenvironment and results in the suppression of macrophage functions. Impaired functions of macrophages result in the suppression/inhibition of cell-mediated immunity leading to inefficient antitumor immune responses. Impaired macrophage population invariably helps in immune selection of tumor leading to uninterrupted growth and progression in the host. Murine T cell lymphoma designated as Dalton’s lymphoma is highly immunosuppressive and invasive tumor of T cell origin, which completely paralyzes the host’s immune system resulting in a very short life span of the host. Progressive growth of Dalton’s lymphoma (DL) cells has been known to inhibit the release of inflammatory cytokines and effector mediator molecules. In this study, we demonstrate that intraperitoneal transplant of DL cells in normal healthy host induces a rapid increase in macrophage cell population during early stage of tumor progression and progressive decrease in tumor-associated macrophage population and reduced survival of macrophages in advance stage of tumor burden.

Anti-tumor Immunity and Mechanism of Immunosuppression Mediated by Tumor Cells: Role of Tumor-Derived Soluble Factors and Cytokines

The immune system plays a crucial role in the protection against tumor growth and progression. However, the activation of the immune system against the neoplastic cells does not always occur and, therefore, tumor cells are able to grow and progress continually in the host. It has now been realized that tumor cells themselves produce many of the important factors that are responsible for dismounting of effective immune response. These tumor-derived soluble factors invariably subdue the functions of almost every immune cell population. Therefore, we attempted to underline the mechanism of anti-tumor immune response and immunosuppression induced by tumor cells.

Heat Shock Proteins (HSP): Future Trends in Cancer Immunotherapy

Heat Shock Proteins (HSPs) are a large family of highly conserved proteins involved in assisting protein folding and unfolding in the cells. HSPs are expressed constitutively as well as inducibly and, interacting with antigen presenting cells, induce the expression of various cytokines and chemokines as well as the maturation and migration of dendritic cells, thus acting themselves as cytokines. HSP-chaperoned antigenic peptides are also generated within the tumor cells. Such chaperoned peptides are released in the extra cellular medium with an association of HSPs by cell stress, death or tumor cell lyses. HSP-peptide complexes from extra cellular medium are taken up by antigen presenting cells through CD91 receptor and are represented or cross-presented by their MHC class I molecules for specific anti-tumor immune response. In addition, HSPs expressed on the cell surface of tumor cells stimulate αβ T-cells and γδ T-cells as well as natural killer (NK) cells that are first-line defense mechanisms. In this manner, HSPs have the ability to stimulate both arms of the effecter mechanism of the immune system. These unique immunological attributes of HSPs are presently becoming the basis for tumor immunotherapy. Tumor-derived HSP-peptide complexes have been demonstrated to serve as anti-tumor vaccines. To date various approaches of vaccination using HSPs have been developed and tested clinically. These HSP-based vaccine approaches can be combined with hyperthermia and CTLA-4 blockade to enhance their anti-tumor potentiality.

Autologous Hsp70 Induces Antigen Specific Th1 Immune Responses in a Murine T-Cell Lymphoma

Heat Shock protein-70 derived from tumor cells is highly immunogenic and induces specific anti-tumor immune response by directly activating cytotoxic CD8+ T cells. Additionally, Hsp70 is known to be a strong activator of antigen presenting cells and therefore, up regulates the production of pro-inflammatory cytokines and chemokines. In this study, we have shown the effect of tumor-derived Hsp70 on the induction of delayed type hypersensitivity reaction in a T cell lymphoma bearing mice. The autologous Hsp70 augments contact hypersensitivity and delayed type hypersensitivity responses in mice challenged with allergen in vehicle and antigens respectively. The adoptive transfer of splenocytes derived from Hsp70 immunized mice is able to enhance delayed type hypersensitivity response in antigen challenged normal and DL-bearing host. Furthermore, adoptive transfer of macrophages incubated with autologous Hsp70 also enhances DTH reactivity in mice. The pro-inflammatory cytokines and C-C chemokines are found to be elevated in the DTH footpad extract of antigen challenged normal and DL-bearing mice. Increased production of IFN-γ and MIP-1α± suggest that autologous Hsp70 augments the recruitment of antigen specific Th1 cells, which further secretes pro-inflammatory cytokines and C-C chemokines mediating the hypersensitivity reaction upon challenge with antigens.

Overexpression of Interleukin-13 in a Murine T-Cell Lymphoma: A Possible Factor of DL-Induced Immunosuppression and Tumor Progression

Interleukin-13 (IL-13) is a TH2 cytokine that plays a crucial role in the pathophysiology of tumors and favor tumor growth and recurrence by negative regulation of tumor immunosurveillance. In the present investigation, we have determined the IL-13 level in the serum and ascitic fluid of the DL-bearing host and the possible source of IL-13 in the ascitic fluid. IL-13 level was elevated in serum and ascitic fluid of host bearing a transplantable T-cell lymphoma. DL cells as well as tumor-associated macrophages express and secrete IL-13 in the milieu, which provide further insight for DL-induced immunosuppression in a tumor-bearing host.

Gender dichotomy in antibody response in a T-cell lymphoma: involvement of IL-13 and gonadal hormones.

Problem  Dalton’s lymphoma (DL) shows very high interleukin (IL)‐13 level in the serum and ascitic fluid. Therefore, in the present study, we investigated if any sexual dichotomy in the level of IL‐13, and resulting B‐cell activation and Ig subclass switching also exist in the tumor‐bearing host.