Is related the hematopoietic stem cells differentiation in the Nile tilapia with GABA exposure?

Neurotoxicant effects of bisphenol A, nonylphenol, and tert‑butyl phenol in the Nile tilapia (Oreochromis niloticus)

Worldwide production of alkyl phenols and ethoxylated alkyl phenols is high due to their broad industrial uses. It has been widely documented that they are endocrine disruptors, and it has been suggested that they could exert neurotoxic effects. However, a lack of information about the neurotoxic effects of APs and APEs prevails. In this study, the bisphenol A (BPA), 4-nonylphenol (NP), and 3‑tert-butylphenol (tertBP) effects on brain and spinal cord of Nile tilapia exposed to environmental concentrations were evaluated by assessing acetylcholinesterase (AChE), butyrylcholinesterase (BuChE), and carboxylesterases (CES) activities, and γ-aminobutyric acid (GABA) levels and their effects were evaluated by molecular docking. BPA and NP, tertBP behave as agonists and antagonists of AChE, BuChE, CES, and GABA, with notable differences among organs. However, none of these compounds or their metabolites interact with the enzymes' catalytic triad, suggesting an indirect alteration of enzymatic activities. While inhibiting these enzymes stand out hydrophobic interactions with the peripheral anion site, contacts with the inner face of the active site and blocking the mouth of the gorge of the active site, and steric hindrance in the enzyme pocket of glutamate decarboxylase (GAD). In contrast, inductions probably are by homotropic pseudo-cooperative phenomenon, where APEs behave as anchors favoring the active site to remain open and interactions that confer a conservative stabilization of the regulatory domain. Although the results of this study are complex, with notable differences between organs and toxicants, they are some of the first evidence of the neurotoxicity of alkylphenols and their ethoxylated derivatives.

Tumor-Infiltrating iNKT Cells Activated through c-Kit/Sca-1 Are Induced by Pentoxifylline, Norcantharidin, and Their Mixtures for Killing Murine Melanoma Cells

The involvement of NK and other cytotoxic cells is considered the first defense line against cancer. However, a significant lack of information prevails on the possible roles played by factors considered characteristic of primitive cells, such as c-kit and Sca-1, in activating these cells, particularly in melanoma models subjected to treatments with substances under investigation, such as the case of norcantharidin. In this study, B16F1 murine melanoma cells were used to induce tumors in DBA/2 mice, estimating the proportions of NK and iNKT cells; the presence of activation (CD107a+) and primitive/activation (c-kit+/Lya6A+) markers and some tumor parameters, such as the presence of mitotic bodies, nuclear factor area, NK and iNKT cell infiltration in the tumor, infiltrated tumor area, and infiltrating lymphocyte count at 10x and 40x in specimens treated with pentoxifylline, norcantharidin, and the combination of both drugs. Possible correlations were estimated with Pearson's correlation analysis. It should be noted that, despite having demonstrated multiple correlations, immaturity/activation markers were related to these cells' activation. At the tumor site, iNKT cells are the ones that exert the cytotoxic potential on tumor cells, but they are confined to specific sites in the tumor. Due to the higher number of interactions of natural killer cells with tumor cells, it is concluded that the most effective treatment was PTX at 60 mg/kg + NCTD at 0.75 mg/kg.

The neurotransmitter receptor Gabbr1 regulates proliferation and function of hematopoietic stem and progenitor cells

Hematopoietic and nervous systems are linked via innervation of bone marrow (BM) niche cells. Hematopoietic stem/progenitor cells (HSPCs) express neurotransmitter receptors, such as the γ-aminobutyric acid (GABA) type B receptor subunit 1 (GABBR1), suggesting that HSPCs could be directly regulated by neurotransmitters like GABA that directly bind to GABBR1. We performed imaging mass spectrometry and found that the endogenous GABA molecule is regionally localized and concentrated near the endosteum of the BM niche. To better understand the role of GABBR1 in regulating HSPCs, we generated a constitutive Gabbr1-knockout mouse model. Analysis revealed that HSPC numbers were significantly reduced in the BM compared with wild-type littermates. Moreover, Gabbr1-null hematopoietic stem cells had diminished capacity to reconstitute irradiated recipients in a competitive transplantation model. Gabbr1-null HSPCs were less proliferative under steady-state conditions and upon stress. Colony-forming unit assays demonstrated that almost all Gabbr1-null HSPCs were in a slow or noncycling state. In vitro differentiation of Gabbr1-null HSPCs in cocultures produced fewer overall cell numbers with significant defects in differentiation and expansion of the B-cell lineage. To determine whether a GABBR1 agonist could stimulate human umbilical cord blood (UCB) HSPCs, we performed brief ex vivo treatment prior to transplant into immunodeficient mice, with significant increases in long-term engraftment of HSPCs compared with GABBR1 antagonist or vehicle treatments. Our results indicate a direct role for GABBR1 in HSPC proliferation, and identify a potential target to improve HSPC engraftment in clinical transplantation.

Sub-basal increases of GABA enhance the synthesis of TNF-α, TGF-β, and IL-1β in the immune system organs of the Nile tilapia

The cells of the immune and neuronal systems share different receptors for cytokines or neurotransmitters, producing feedback responses between both systems. Cytokines such as IL-1β and TNF-α can induce inflammation; however, the secretion of these molecules can be modulated by anti-inflammatory cytokines, as is the case for TGF-β, as well as by different hormones or neurotransmitters such as the γ-aminobutyric acid (GABA). In this study, we evaluated the secretion of IL-1β, TNF-α, and TGF-β under basal conditions, in the head of the kidney, spleen, thymus, and serum of the Nile tilapia, as well as their release induced by different sub-basal increases of GABA. We found that at the higher dose of GABA these cytokines were synthesised at a higher concentration compared to the control group. These results may suggest that there is feedback between both systems and that GABA plays a role in the modulation of the immune response.