N-acetyl tryptophan glucopyranoside (NATG) as a countermeasure against gamma radiation-induced immunosuppression in murine macrophage J774A.1 cells

Abstract

Radiation exposure to immune system induces imbalance in cytokines expression involved in Th1/Th2 homeostasis perturbations. In the present study, N-acetyl tryptophan glucoside (NATG), a bacterial secondary metabolite, was evaluated for its possible radioprotective potential to immune system using J774A.1 murine macrophages. In this study, expression of IFN-γ, TNF-α, IL-10, IL-2, IL-12, IL-13 and IL-17A cytokines was analyzed in irradiated and NATG pretreated cells using ELISA assay. Results of the study indicated that irradiated macrophages (NK-1Rcells) pretreated with NATG showed higher (p < .05) survival at all observed time-intervals (2 h-48 h) as compared to irradiated (20Gy) cells that were not pretreated with NATG. However, NATG pretreatment to irradiated HEK293T cells (that did not express NK-1Receptor) did not provide significant survival, suggesting NK-1R involvement in NATG-mediated radioprotection. Cytokine expression analysis demonstrated that NATG pre-treated plus irradiated J774A.1 murine macrophages exhibited increased IFN-γ levels (∼90%) with significant decrease in TNF-α at 24h as compared to irradiated cells. Further, significant decrease (∼20%) in IL-10 and IL-2 (∼26%) levels was observed in irradiated macrophages pretreated with NATG as compared to only irradiated cells. A sharp improvement in IL-17A (∼92%) and IL-12 (∼116%) expression was observed in irradiated macrophages pretreated with NATG as compared to only irradiated cells. Hence, NATG pre-treatment to irradiated macrophages induced IFN-γ, IL-17A and IL-12 expression, but suppresses TNF-α, IL-10 and IL-2 expressions. Conclusively, NATG pretreatment overcomes radiation-induced Th2 immune response by improving Th1 responsive cytoprotective cytokines IFN-γ, IL-17A and IL-12 in irradiated macrophages possibly by NK-1R antagonistic mechanism, and thus contributes to radioprotection.

In vitro stimulatory effect of N‐acetyl tryptophan‐glucopyranoside against gamma radiation induced immunosuppression

“…Radiation exposure to immune system results in creating a discrepancy in the Th 1 /Th 2 homeostatic balance of the body. In our previous study, it was revealed that the bacterial secondary metabolite, NATG, mainly exerts radioprotective effect by priming the macrophages via interactions with NK‐1 receptor of cells . Hence, to further evaluate the immunological implications of gamma radiation (2 Gy) induced damages, this study was designed.…”

“…In our previous study, it was revealed that the bacterial secondary metabolite, NATG, mainly exerts radioprotective effect by priming the macrophages via interactions with NK-1 receptor of cells. 4,34 Hence, to further evaluate the immunological implications of gamma radiation (2 Gy) tion. 4 Similar results were obtained in this study for exposure with 2…”

“…Recent findings have displayed radioprotective and immunoprotective capability of another novel secondary metabolite, N ‐acetyl tryptophan glucopyanoside (NATG), purified and characterized from the radioresistant bacterium Bacillus sp. INM‐1 . This study is mainly focused on effects of NATG on radioprotective efficacy, regulation of cell cycle progression, and Th 1 /Th 2 immune response homeostasis in irradiated murine macrophage J774A.1 cells.…”

Pharmacology of natural radioprotectors

“…NATG pretreatment mediates radioprotection by preventing IR-induced apoptosis through increase of the cytoprotective cytokines IFN-γ, IL-17A, and IL-12 (Malhotra et al 2015 ). NATG pretreatment has also been demonstrated to protect J774A.1 macrophages against IR-induced DNA damage (Malhotra et al 2016 ) and was able to significantly enhance antioxidant enzymes in response to IR-induced damage in murine macrophages (Malhotra et al 2018 ).…”

Immunological modulation of the Th1/Th2 shift by ionizing radiation in tumors (Review)

“…Various doses of IR mediate a distinct Th1/Th2 cytokine imbalance. High-dose IR (HDIR, ≥2 Gy) induces a Th2 shift (Table II) (39)(40)(41)(42)(43)(44)(45)(46)(47)(48)(49)(50)(51)(52)(53)(54)(55)(56). Irradiation at 5 Gy notably promotes the secretion of Th2 cytokines, including IL-4, IL-5 and IL-10, most likely through the upregulation of the transcription factor, GATA-3 and c-Maf.…”