Arbind Acharya

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.

Targeting Hsp70: A possible therapy for cancer

In all organisms, heat-shock proteins (HSPs) provide an ancient defense system. These proteins act as molecular chaperones by assisting proper folding and refolding of misfolded proteins and aid in the elimination of old and damaged cells. HSPs include Hsp100, Hsp90, Hsp70, Hsp40, and small HSPs. Through its substrate-binding domains, Hsp70 interacts with wide spectrum of molecules, ranging from unfolded to natively folded and aggregated proteins, and provides cytoprotective role against various cellular stresses. Under pathophysiological conditions, the high expression of Hsp70 allows cells to survive with lethal injuries. Increased Hsp70, by interacting at several points on apoptotic signaling pathways, leads to inhibition of apoptosis. Elevated expression of Hsp70 in cancer cells may be responsible for tumorigenesis and for tumor progression by providing resistance to chemotherapy. In contrast, inhibition or knockdown of Hsp70 reduces the size of tumors and can cause their complete regression. Moreover, extracellular Hsp70 acts as an immunogen that participates in cross presentation of MHC-I molecules. The goals of this review are to examine the roles of Hsp70 in cancer and to present strategies targeting Hsp70 in the development of cancer therapeutics.

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.

Carboxylic group-induced synthesis and characterization of selenium nanoparticles and its anti-tumor potential on Dalton's lymphoma cells

Carboxylic group-induced synthesis of selenium nanoparticles (SeNPs) was achieved using sodium selenosulphate as a precursor. The particles were stabilized and capped with 0.01% polyvinyl alcohol under ambient conditions. This is a simple and easy method of producing SeNPs in a size range from 35 to 105 nm. The synthesized SeNPs were purified by centrifugation at 11,500 × g for 20 min and characterized by UV-visible spectroscopy, FTIR spectroscopy, XRD, DSC and TEM. It was observed that the synthesized SeNPs showed differences in their absorption spectra, phase composition and crystal structure, thermodynamic behaviour, size and shape. Further, to confirm anti-tumour potential of the synthesized SeNPs induced by the carboxylic group of acetic acid, pyruvic acid and benzoic acid, cell viability assay, nuclear morphology testing and DNA fragmentation assay were carried out using Daltons lymphoma (DL) cells. DL cells treated with the SeNPs showed reduced cell viability, altered nuclear morphology, typical apoptotic DNA ladder and apoptosis. Therefore, these SeNPs may have therapeutic relevance to treat this type of cancer.

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.

HSF1-mediated regulation of tumor cell apoptosis: a novel target for cancer therapeutics

Programmed cell death/apoptosis is a genetically conserved phenomenon involved in many biological processes including reconstruction of multicellular organisms and elimination of old or damaged cells. It is regulated by the activation/deactivation of PKC in response to exogenous and endogenous stimuli. PKC is activated under stress by a series of downstream signaling cascades, which ultimately induce HSF1 activation, which results in overexpression of heat shock proteins. Overexpression of heat shock proteins interferes in the apoptotic pathway, while their blocking results in apoptosis. Therefore, HSF1 could be a novel therapeutic target against a variety of tumors. Several pharmacological inhibitors of PKC have been demonstrated to exert inhibitory effects on the activation of HSF1 and, therefore, induce apoptosis in tumor cells. However, studies regarding the role of pharmacological inhibitors in the regulation of apoptosis and possible anti-tumor therapeutic intervention are still unknown or in their infancy. Therefore, an attempt has been made to delineate the precise role of HSF1 in the regulation of apoptosis and its prospects in cancer therapeutics.

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.

Chelerythrine induces reactive oxygen species-dependent mitochondrial apoptotic pathway in a murine T cell lymphoma

Chelerythrine is a well-known protein kinase C inhibitor and potential antiproliferative and antitumor pharmacological agent. Chelerythrine inhibits/suppresses the HSF1 phosphorylation by inhibiting PKC and blocks the nuclear migration and subsequent synthesis of hsp70 leading to reduced cell viability and activation of apoptotic machinery. Chelerythrine is also known to enhance the production of reactive oxygen intermediate that is strong activator of apoptosis in high concentration. Therefore, the present study intended to investigate the role of chelerythrine-induced reactive oxygen intermediate on the viability and apoptosis of Daltons lymphoma cells. Enhanced production of reactive oxygen species in Daltons lymphoma (DL) cells was observed upon treatment of chelerythrine only which was seen completely abolished on treatment of mitochondrial complex inhibitors rotenone and malonate, and anti-oxidant, N-acetyl-l-cysteine. Increased number of DL cells undergoing apoptosis, as observed by fluorescent microscopy and flow cytometry analysis, in chelerythrine only-treated group was seen that was significantly inhibited on treatment of mitochondrial complex inhibitors and anti-oxidants. Staurosporine, on the other hand, does not lead to enhanced production of reactive oxygen intermediate in DL cells.

Suppressed Expression of Homotypic Multinucleation, Extracellular Domains of CD172α (SIRP‐α) and CD47 (IAP) Receptors in TAMs UpRegulated by Hsp70–Peptide Complex in Dalton's Lymphoma

CD172α and CD47 are members of glycoprotein expressed on macrophages and various immune cells, promote immune recognition and T cell stimulation that priming phagocytosis of pathogens and apoptotic bodies and malignant cell. Tumour‐releasing immunosuppressive factor promotes tumour growth and transforms the tumour resident M1 phenotype of macrophage to M2 phenotype (TAMs) that promotes tumour progression by downregulating the expression of different surface receptor including CD172α and CD47. Recent studies have reported that CD172α and CD47 are involved in the pathogenesis and promote malignancies such as lymphoma, leukaemia, melanoma, lung cancer and multiple myeloma, and their expression varies during infection and malignancies. Autologous Hsp70 is well recognized for its role in activating macrophages leading to enhance production of inflammatory cytokines. It has been observed that Hsp70 derived from normal tissues do not elicit tumour immunity, while Hsp70 preparation from tumour cell was able to elicit tumour immunity. However, the role of exogenous autologous hsp70 on the formation of giant cells is completely unknown. Therefore, in the present study, we sought to investigate the effect of Hsp70–peptide complex on the expression of CD172α and CD47 receptors in normal peritoneal macrophages (NMO) and TAMs. Finding shows that the expression of CD172α and CD47 enhances in TAMs and it reverts back the suppressed function of TAMs into M1 state of immunoregulatory phenotype that promotes tumour regression by enhanced multinucleation and phagocytosis of malignant cells and significantly enhances the homotypic fusion of macrophages and polykaryon formation in vitro by enhancing the expression of SIRPα and IAP.

Activation of p53-dependent/-independent pathways of apoptotic cell death by chelerythrine in a murine T cell lymphoma

Abstract The p53 tumor suppressor protein has been implicated as an activator of apoptosis. In order to investigate the effect of chelerythrine and staurosporine on the activation of p53-dependent/-independent pathways of Dalton lymphoma (DL) cell death, cells were treated with chelerythrine and staurosporine for 1 h, 3 h and 6 h, respectively. It was found that treatment with chelerythrine and staurosporine increased the expression of total-p53/phospho-53 (ser-15) significantly at protein and mRNA levels, which resulted in activation of the p53-dependent apoptotic pathway in DL cells. In addition, increased activities of cyt-c, caspase-9 and caspase-3 and degradation of DNA into fragments confirmed activation of the p53-independent apoptotic pathway in p53 knockdown RNAi-DL cells. In brief, the present study demonstrated activation of p53-dependent/-independent apoptotic pathways in DL cells. Therefore, targeting of p53-dependent/-independent apoptotic pathways may lead to the possibility of designing and developing better therapeutic regimens to treat DL and other human cancers.