Laboratory of Pathophysiology, Butantan Institute, São Paulo, SP, Brazil.
Faculty of Medicine, University City of São Paulo-UNICID, São Paulo, SP, Brazil.
Toxicon. 2022 Oct 15;217:46-55. doi: 10.1016/j.toxicon.2022.07.011. Epub 2022 Aug 15.
Crotoxin (CTX), the major toxin of Crotalus durissus terrificus snake venom, induces an inhibitory effect on tumor development and modulates the functions of macrophages (MØs), which play a key role as a defense mechanism against tumor growth. In early tumor progression stage, MØs are avidly phagocytic (inflammatory cell), releasing reactive nitrogen intermediates-RNI/ROI and cytokines TNF-α, IL-1β, and IL-6. However, when the tumor has been developed, tumor-associated MØ (angiogenic cell) presents a decrease in the mentioned activities. We reported that CTX stimulates HO release, NO production and secretion of cytokines by peritoneal MØs obtained from non-tumor-bearing rats. Considering that the mentioned mediators control tumor growth, it is mandatory to investigate whether CTX stimulates the production of these mediators by MØs obtained from tumor-bearing animals. The aim of this work was then to evaluate the CTX effect on metabolism and functions of peritoneal MØs obtained from Walker 256 tumor-bearing rats. For this purpose, male Wistar rats were subcutaneously inoculated in the right flank with 1 mL sterile suspension of 2 × 10 Walker 256 tumor cells. CTX (18 μg per animal) was subcutaneously administered in two protocols: a) on the 1st day of tumor cell injection and b) on the 4th day of tumor cell inoculation. In both protocols, MØs were obtaining on the 14th day of tumor cell inoculation to evaluate the release of HO NO, and pro-inflammatory cytokines (IL-1β, TNFα, and IL-6); maximal activity of hexokinase, glucose-6-phosphate dehydrogenase, citrate synthase, and CO production from [U-C]-glucose and [U-C]-glutamine. The treatment with CTX stimulated the release of NO, HO, and cytokines, and glucose and glutamine metabolism. Metabolic and functional changes induced by CTX were accompanied by a decrease of tumor growth as indicated by tumor fresh weight and diameter. These results indicate CTX not only as a scientific tool to investigate changes in metabolism and functions of peritoneal MØs but also for a better understanding of the mechanisms involved in tumor growth.
响尾蛇毒素（CTX）是响尾蛇蛇毒的主要毒素，它对肿瘤的发展有抑制作用，并调节巨噬细胞（MØ）的功能，巨噬细胞在肿瘤生长的防御机制中起着关键作用。在肿瘤早期进展阶段，MØs 吞噬作用（炎症细胞）强烈，释放活性氮中间产物-RNI/ROI 和细胞因子 TNF-α、IL-1β 和 IL-6。然而，当肿瘤已经发展时，肿瘤相关的 MØ（血管生成细胞）表现出上述活性的降低。我们报道 CTX 刺激非荷瘤大鼠腹腔 MØ 释放 HO、产生 NO 和分泌细胞因子。考虑到这些介质控制肿瘤的生长，有必要研究 CTX 是否刺激来自荷瘤动物的 MØ 产生这些介质。因此，这项工作的目的是评估 CTX 对来自 Walker 256 荷瘤大鼠腹腔 MØ 的代谢和功能的影响。为此，雄性 Wistar 大鼠在右侧肋腹皮下接种 1ml 无菌 2×10 Walker 256 肿瘤细胞混悬液。CTX（每只动物 18μg）以两种方案皮下给药：a）在肿瘤细胞注射的第 1 天和 b）在肿瘤细胞接种的第 4 天。在这两种方案中，均在肿瘤细胞接种后的第 14 天获得 MØ，以评估 HO-NO 和促炎细胞因子（IL-1β、TNFα 和 IL-6）的释放；己糖激酶、葡萄糖-6-磷酸脱氢酶、柠檬酸合酶的最大活性，以及[U-C]-葡萄糖和[U-C]-谷氨酰胺的 CO 产生。CTX 处理刺激了 NO、HO 和细胞因子的释放，以及葡萄糖和谷氨酰胺的代谢。CTX 诱导的代谢和功能变化伴随着肿瘤生长的减少，如肿瘤新鲜重量和直径所示。这些结果表明，CTX 不仅是研究腹腔 MØ 代谢和功能变化的科学工具，而且有助于更好地理解肿瘤生长涉及的机制。
