Utpala Chattopadhyay

Antitumor, Immunomodulatory and Anti-HIV Effect of Mangiferin, a Naturally Occurring Glucosylxanthone

Mangiferin, a C-glucosylxanthone (1,3,6,7-tetrahydroxyxanthone-C2-beta-D-glucoside) purified from plant sources was shown to have in vivo growth-inhibitory activity against ascitic fibrosarcoma in Swiss mice. Following in vivo or in vitro treatment, it also enhanced tumor cell cytotoxicity of the splenic cells and peritoneal macrophages of normal and tumor-bearing mice. In vitro treatment of the splenic cells of tumor-bearing mice with mangiferin resulted in augmented killing of tumor cells, both resistant and sensitive to natural killer cells. Mangiferin was also found to antagonize in vitro the cytopathic effect of HIV. The drug appears to act as a potent biological response modifier with antitumor and antiviral effect.

Prolactin regulates antitumor immune response through induction of tumoricidal macrophages and release of IL-12

The involvement of PRL in regulating monocyte/macrophage functions is suggested by the presence of PRL‐Rs in these cells. Here, we show that PRL, though it failed to activate mouse peritoneal resident macrophages (RMs), acted as a second signal and activated mouse peritoneal inflammatory macrophages (EMs) to a tumoricidal state. The cytotoxicity of mouse tumor‐associated macrophages (TAMs) isolated at day 1 of tumor (Ehrlich ascites carcinoma, EAC) growth was enhanced by PRL. However, with progression of tumor growth, TAMs became nonresponsive to the hormone. PRL‐induced killing of P815 target cells by EMs and TAMs was independent of TNF but correlated with the hormone‐induced augmentation of NO2− and O2− release in these macrophages. Administration of PRL in vivo inhibited EAC growth and augmented NO2− release by TAMs. PRL synergized with the TH1 cytokine IFN‐γ, a known activator of macrophages, in inducing tumor killing and release of NO2− from EMs and TAMs. The hormone might activate macrophages at least partially, through the release of IFN‐γ as anti‐IFN‐γ blocked IFN‐γ– as well as PRL‐induced cytotoxicity in EMs. The TH2 cytokine IL‐4 suppressed PRL‐induced activation of macrophages. PRL induced release of IL‐12 from EMs also, which suggested that the hormone might drive the TH1 response through IL‐12. Our observations further suggest that PRL alone and in synergy with IFN‐γ, released through induction of IL‐12, may generate tumoricidal macrophages and thus regulate the antitumor immune response of tumor hosts.

Macrophage inflammatory protein (MIP)1α and MIP1β differentially regulate release of inflammatory cytokines and generation of tumoricidal monocytes in malignancy

The C–C chemokines, macrophage inflammatory protein (MIP)1α and MIP1β are potent chemoattractants for the monocytes, which form an important component of the stroma of tumor tissue and may regulate tumor growth and associated inflammation. We examined the role of MIP1α and MIP1β in inducing the release of inflammatory cytokines and the generation of tumoricidal monocytes from the peripheral blood monocytes (PBM) of healthy women and patients with carcinoma of breast (CaBr). Interleukin-1 (IL-1) and tumor necrosis factor (TNF) α release by the PBM was markedly stimulated by MIP1α in CaBr patients, but only marginally so in healthy women. In contrast, MIP1β stimulated the release of these cytokines by the PBM of healthy women, but failed to do so in CaBr patients. MIP1α, but not MIP1β, synergized with LPS in inducing the release of IL-1 from the PBM of both healthy women and CaBr patients. Both MIP1α and MIP1β augmented respiratory bursts in PBM and generated tumoricidal PBM that killed T24 cells, MIP1α being more effective in CaBr patients and MIP1β in healthy women. IFN-γ co-stimulated and IL-4 suppressed MIP1α and β-induced cytotoxicity in PBM. The synergy of IFN-γ was more marked with MIP1α than with MIP1β. The differential effects of MIP1α and MIP1β on the PBM of healthy women and CaBr patients co-related with the levels of expression of CCR1 and CCR5 in these monocytes. The expression of CCR5 was higher than that of CCR1 in the PBM of healthy women and the PBM of the CaBr patients showed overexpression of CCR1 and downregulation of CCR5.

Prolactin induced reversal of glucocorticoid mediated apoptosis of immature cortical thymocytes is abrogated by induction of tumor

Glucocorticoid (GC) and prolactin (PRL) are the two neuroendocrines that regulate thymocyte differentiation and maintain the immune homeostasis during stress. We found that dexamethasone (Dex), a synthetic GC, induced apoptosis in normal immature cortical thymocytes which remained unaltered in the presence of Elrichs ascitic carcinoma (EAC). PRL protected the normal CD4+ CD8+ cortical thymocytes from Dex-induced apoptosis but failed to alter the effect of Dex in tumor-bearing mice. Dex-treated normal thymocytes became unresponsive to PRL in presence of tumor cell culture supernatant. Low binding affinity of the microsomal membranes of thymocytes to PRL and absence of the mRNA of a particular form of prolactin receptor (PRL-R) suggest the presence of a different PRL-R in CD4+ CD8+ thymocytes of EAC-bearing mice. The induction of tumor may alter the PRL-R that can be correlated with the failure of PRL in rescuing CD4+ CD8+ immature cortical thymocytes from GC induced death.

Prolactin response of NK cells, but not of LAK cells, is deficient in patients with carcinoma of oral cavity and during aging

The regulatory role of prolactin (Prl) on peripheral blood natural killer (NK) and lymphokine‐activated killer (LAK) cell activities was studied in young (mean age, 40 years) and elderly (mean age, 68 years) healthy men and patients with carcinoma of the oral cavity (oral cancer). The peripheral blood NK cells, but not the LAK cells, were found to be depressed in oral cancer patients compared with age‐matched healthy men. However, age‐associated deficiency in both NK and LAK cell activity was observed in healthy men and cancer patients. Prl produced dose‐dependent inhibition (1, 10, 100 or 250 ng/ml) or stimulation (25–50 ng/ml) of resting NK cells in young groups of healthy men and cancer patients. In elderly groups less or no response of the NK cells to low doses of Prl (1–10 ng/ml) was evident. The NK cells of young and elderly healthy men were stimulated by human recombinant interleukin‐2 (rlL‐2) (100 U/ml), and Prl (1–250 ng/ml) inhibited these cells. In oral cancer patients an altered response to low doses of Prl (1–50 ng/ml) was observed in IL‐2‐stimulated NK cells, which also revealed malignancy‐associated loss of IL‐2 response. In contrast, there was no malignancy or age‐associated change in Prl response of the LAK cells. Treatment of peripheral blood lymphocytes of both healthy men and oral cancer patients for 5 days with Prl (50 ng/ml) in the presence of low concentration of serum generated LAK cells.

Age related natural killer activity of peripheral blood lymphocytes from healthy subjects and cancer patients. A comparative in vitro study with interleukin-2.

Aims and Beckground Natural killer (NK) cell activity is known to be depressed in neoplastic diseases, and ageing influences the cytotoxicity of NK cells. However, very little information is available on the responsiveness of NK cells of cancer patients to the stimulating effects of interleukin-2 (IL-2) as a function of age. Methods We assessed in vitro IL-2 induced modulation of NK activity in peripheral blood lymphocytes (PBL) from 7 young (30-50 years) and 9 elderly (55-78 years) male patients with carcinoma of the oral cavity. In these patients generation of lyphokine activated killer (LAK) activity was also studied. NK and LAK activity of PBL were measured in 14 age and sex matched healthy volunteers as who served as conrols. Cytotoxicity of the NK and LAK cells was assayed against NK sensitive K562 and NK resistant Daudi cells in 4-h 51 Cr-release assays. Results NK activity in the cancer patients was significantly lower than that in healthy volunteers. In both groups the younger subjects had higher NK activity than the elderly ones. NK cells of both young and elderly healthy controls responded similarly to 24-hour in vitro exposure to human recombinant IL-2 (rIL-2, 100 u/ml) with highly increased cytotoxicity. Though there was significant enhancement of NK activity with rIL-2 in both young and elderly cancer patients, the rIL-2 induced NK cytotoxicity in the elderly patients was much lower than the basal level of NK activity of the age matched controls. Interestingly, LAK activity, generated by 3-7 days of in vitro exposure of PBL to rlL-2 was comparable in the cancer patients and healthy volunteers Conclusion The data suggest serious impairment of NK function in elderly patients with oral carcinoma. Generation of LAK activity with exogenous IL-2 could be an important modality of treatment in these patients.

Interferon-α2b Restores the Impaired Chemotactic Activity of Peripheral Blood Mononuclear Cells from Head and Neck Squamous Cell Carcinoma Patients by Modulating CXC Receptor Ligand Interaction

We have studied the immunomodulatory effects of interferon-alpha2b (IFN-alpha2b) in rectification of the dysregulated IFN-gamma-dependent chemokines and their receptor CXCR3 splice variants in head and neck squamous cell carcinoma-peripheral blood mononuclear cells (HNSCC-PBMC). CXCR3 expression was upregulated in HNSCC-PBMC, with the demonstration of poor chemotactic function. CXCR3 upregulation possibly represents the increased synthesis of CXCR3B splice variant, without significant change in CXCR3A. Upregulated expression of CXCR3B was downregulated following in vitro IFN-alpha2b treatment of HNSCC-PBMC. Upregulation of CXCR3A+B by IFN-alpha2b with downregulation of the CXCR3B indirectly suggests that the upregulation of the CXCR3A splice variant induces cellular migration. On the other hand, the stimulation of PBMC with IFN-alpha2b maintains physiological homeostasis of CXCR3 ligands, CXCL10 and CXCL9, and increases the secretion of IFN-gamma. The suppressed chemotactic ability of HNSCC-PBMC could be restored either by in vitro treatment of PBMC with IFN-alpha2b or during the use of IFN-alpha2b stimulated PBMC supernatant as a chemoattractant. Chemoattraction process is guided at the level of both receptor and its ligands, as confirmed by neutralization studies. IFN-alpha2b possibly controls chemotaxis by regulating the interaction between CXCL10 and CXCR3A. Neutralization of IFN-gamma downregulates the IFN-alpha2b mediated CXCL10 release, suggesting the active role of IFN-gamma in the transduction of chemotactic signal for the migration of cytotoxic T/NK cells at the tumor site.

Tumor associated release of interleukin-10 alters the prolactin receptor and down-regulates prolactin responsiveness of immature cortical thymocytes

The soluble factors produced either by Ehrlichs ascites carcinoma (EAC) or thymic adherent cells (TAC) of tumor-bearing mice comprising of CD11b(+) and CD11c(+) antigen-presenting cells caused a sharp decrease in prolactin (PRL)-induced ConA-mediated effect on survival of PNA(+) thymocytes. Similar suppression of PRL-induced effect was observed when the cells were cocultured with TAC of EAC-bearing mice. Anti-IL-10 antibody could reverse the PRL inability to induce ConA-mediated effect on PNA(+) thymocyte survival, indicating the presence of IL-10 in EAC culture supernatant (EAC sup) and thymic microenvironment. IL-10 could block PRL-induced proliferation of PNA(+) thymocytes without affecting spontaneous apoptosis. IL-10 altered the expression of the long-form (LF) of PRL-R and reduced the PRL binding of the cells, suggesting down-regulation of the PRL effect on PNA(+) thymocyte by the cytokine. Induction of tumor, which was found to increase the IL-10 secretion by TAC, also modified the PRL-R (LF) to PRL-R (SF). Since PRL plays a role in survival, proliferation and differentiation of lymphoid progenitor cells, the tuning of PRL action by IL-10 may be a possible mechanism of depletion of immature cortical thymocytes and thymic atrophy in tumor-bearing mice.

Prolactin regulates macrophage and NK cell mediated inflammation and cytotoxic response against tumor

Abstract Prolactin (PRL) is known to stimulate lymphocyte growth and function, but its role in regulating innate immune response is not clear. We show that PRL, as a secondary signal, can induce tumoricidal macrophages in mice and augment tumor target killing by human monocytes and NK cells. PRL also induces IL-1, NO 2 − , and O 2 − release by the macrophages. Through release of IL-12 and IFN-γ, PRL regulates activation of monocytes/macrophages and NK cells. PRL mediated factivation of monocytes/macrophages is inhibited by IL-4 and in malignancy. A defect in PRL-receptor expression by macrophages may occur in malignancy.

Effect of mangiferin, a naturally occurring glucosylxanthone, on reproductive function of rats.

Female albino rats, treated with mangiferin at daily doses of 5 mg/100 g ip for 3 days during mid-gestation, showed complete fetal resorption. Administration of a mangiferin-Cu2+ (1:1) complex, along with mangiferin, attenuated the effect of mangiferin and restored the completion of gestation in 60% of the rats. The mother rats that completed gestation successfully did not show any post-natal abnormality, and the litters born were also normal. Mangiferin treatment of non-gestating female rats caused little or no changes in their organ weights. However, changes in the protein and protein-DNA ratios of several organs were statistically significant. Mangiferin also modified the ascorbic acid retention capacity of adrenal glands of male rats in vitro. These findings are appraised in view of mangiferin as a potential antifertility agent.