背景:疟疾,以炎症和多器官并发症为特征,由于抗药性疟疾寄生虫的兴起,需要新的化学疗法,这是一个严重的健康问题。柚皮苷(NGN),黄烷酮苷(柚皮素7-O-新橙皮苷),具有广泛的药理活性,但它对疟疾的作用,单独和组合,没有深入调查。
目的:评估NGN单独和与氯喹(CQ)联合治疗对CQ耐药的疟原虫的药理作用,并阐明其潜在的作用方式。
方法:通过分析炎性细胞因子产生,在用疟原虫色素刺激的小鼠小胶质细胞中评估NGN的抗炎潜力。随后,使用固定比率组合方法,单独测试了NGN的抗疟原虫潜能,并与CQ联合使用。Further,我们评估了NGN对耐CQ的尼日利亚约氏疟原虫N67菌株的抗疟功效(P.yoelii),无论是单独还是与CQ结合,通过测量寄生虫血症和存活率。了解NGN对疟疾诱导的小鼠炎症的影响,我们测量了活化的NF-κB信号升高的促炎细胞因子。这些发现得到了疟疾感染小鼠肝脏和脑组织mRNA和免疫组织化学分析的支持。
结果:我们的研究表明NGN具有抗疟原虫活性,与CQ结合使用时进一步增强。在50µM时,NGN显着降低了合成疟原虫素刺激的小胶质细胞中促炎细胞因子的升高。与约氏疟原虫感染的小鼠相比,NGN(12.5mgkg-1)显着降低了小鼠的寄生虫血症,导致长达13天的生存期。联合给予NGN和CQ后,生存率提高了20天。NGN,如脑和肝组织的免疫组织化学检查所示,干扰了NF-κB途径,潜在降低促炎细胞因子(TNF-α,IL-1β,IL-18,IFN-γ,和IL-6)。这得到了炎症调节基因(TGFβ,Nrf2,HO-1和iNOS)和炎症刺激基因的下调(NF-κB,NLRP3和胱天蛋白酶-1)。组织病理学分析表明NGN具有使肝脏和脑组织恢复正常的潜力。脑组织中ICAM-1蛋白的表达和产生的显著减少暗示了NGN的有益作用,指向其减轻脑部病理的潜力。
结论:这项研究的结果表明,NGN是一种有希望的药物样候选药物,可用于治疗CQ耐药寄生虫诱导的疟疾发病机制,并与标准抗疟药物联合使用,通过调节NF-κB介导的炎症。
BACKGROUND: Malaria, characterised by inflammation and multi-organ complications, needs novel chemotherapeutics due to the rise of drug-resistant malaria parasites, which is a serious health issue. Naringin (NGN), a flavanone glycoside (naringenin 7-O-neohesperidose), has a broad spectrum of pharmacological activities but its effect against malaria, alone and in combination, was not deeply investigated.
OBJECTIVE: To assess the pharmacological efficacy of NGN alone and in combination with
chloroquine (CQ) against a Plasmodium strain resistant to CQ and to elucidate its potential mode of action.
METHODS: The anti-inflammatory potential of NGN was assessed in mouse microglial cells stimulated with hemozoin by analyzing inflammatory cytokines production. The anti-plasmodial potential of NGN was subsequently tested alone and in combination with CQ against the K1 strain of Plasmodium using the fixed ratio combination method. Further, we evaluated NGN\'s antimalarial efficacy against the CQ-resistant Plasmodium yoelii nigeriensis N67 strain (P. yoelii), both alone and in combination with CQ, by measuring parasitemia and survival rates. To comprehend the impact of NGN on malaria-induced inflammation in mice, we measured pro-inflammatory cytokines elevated by activated NF-кB signalling. These findings were supported by mRNA and immunohistochemical analyses of malaria-infected mice\'s liver and brain tissues.
RESULTS: Our study demonstrated that NGN displayed anti-plasmodial activity, which was further augmented when combined with CQ. At 50 µM, NGN significantly reduced the elevation of pro-inflammatory cytokines in synthetic hemozoin-stimulated microglial cells. Compared to P. yoelii-infected mice, NGN (12.5 mg kg-1) significantly reduced parasitemia in mice, resulting in a survival period of up to 13 days. Survival improved by up to 20 days when NGN and CQ were given in combination. NGN, as revealed by immunohistochemical examination of brain and liver tissues, interfered with the NF-кB pathway, potentially reducing the elevation of pro-inflammatory cytokines (TNF-α, IL-1β, IL-18, IFN-γ, and IL-6). This was supported by the overexpression of inflammation-regulatory genes (TGFβ, Nrf2, HO-1, and iNOS) and the downregulation of inflammation-stimulating genes (NF-κB, NLRP3, and caspase-1). Histopathological analysis demonstrated the potential of NGN to restore liver and brain tissues to normal. The substantial decrease in the expression and production of ICAM-1 protein in the brain tissue implies the beneficial effects of NGN, pointing towards its potential for mitigating brain pathology.
CONCLUSIONS: The findings of this study revealed NGN as a promising drug-like candidate for the management of CQ-resistant parasite-induced malaria pathogenesis for adjunctive therapy in combination with standard antimalarial drugs through its modulation of the NF-κB-mediated inflammation.