Objective: To formulate a ZIF-8 nano mimetic enzyme conjugated with platinum metal (ZIF-8@Pt) that can scavenge reactive oxygen species (ROS) and to explore its potential applications in the treatment of rheumatoid arthritis (RA).
Methods: The ZIF-8@Pt nanozyme was created by in situ reduction. Characterization of the nanozyme was then performed and its ability to mimic enzymes was investigated. Cell experiments were conducted using RAW264.7 cells, which were divided into three groups, including the untreated group (UT), the positive control group receiving lipopolysaccharide (LPS), which was designated as the LPS group, and the ZIF-8@Pt group receiving ZIF-8@Pt and LPS treatment. The cell experiments were conducted to evaluate the anti-inflammatory properties of ZIF-8@Pt through scavenging intracellular ROS. On the other hand, a collagen-induced arthritis (CIA) model was induced in rats. Similar to the group designations in the cell experiments, the rats were assigned to three groups, including a healthy control group (the UT group), a positive control group receiving a local injection of PBS solution in the knee joint, which was referred to as the control group, and a treatment group receiving a local injection of ZIF-8@Pt solution in the knee joint, which was referred to as the ZIF-8@Pt group. General evaluation, imaging observation, assessment of inflammatory factors, and pathological evaluation were performed to assess the therapeutic efficacy of ZIF-8@Pt against RA.
Results: The in vitro experiment revealed significant difference in the levels of intracellular ROS and LPS-induced M1-type macrophage polarization between the LPS group and the ZIF-8@Pt group (P<0.05). The in vivo experiment showed that significant difference in the levels of inflammatory factors, including interleukin-1β (IL-1β), C-reactive protein (CRP), tumor necrosis factor-α (TNF-α), and arginase-1 (Arg-1) in the knee joints of the CIA rats between the LPS group and the ZIF-8@Pt group (P<0.05). Comparing the findings for the ZIF-8@Pt group and the control group, pathology assessment revealed that ZIF-8@Pt reduced local hypoxia and suppressed osteoclastic activity, neovascularization, and M1-type macrophage polarization (P<0.05).
Conclusion: The ZIF-8@Pt enzyme mimetic inhibits macrophage inflammatory polarization by ROS scavenging, thereby improving inflammation in RA. Furthermore, the ZIF-8@Pt nanozyme improves the hypoxic environment and inhibits angiogenesis and bone destruction, demonstrating promising therapeutic efficacy for RA.
目的: 构建具备清除活性氧（reactive oxygen species, ROS）能力的铂金属掺杂ZIF-8纳米仿酶制剂（ZIF-8@Pt）并探讨其对类风湿关节炎（rheumatoid arthritis, RA）的治疗效果。
方法: 通过原位还原的方式得到ZIF-8@Pt纳米制剂并进行表征和仿酶能力测试后，使用RAW264.7细胞，分未处理组（untreated, UT）、阳性对照组（lipopolysaccharide, LPS）及治疗组（ZIF-8@Pt）进行细胞实验，探讨其清除胞内ROS实现抗炎的能力。使用胶原诱导大鼠建立关节炎模型（collagen-induced arthritis, CIA），分健康对照组（UT）、阳性对照组（Control组，注射PBS）及治疗组（ZIF-8@Pt，注射ZIF-8@Pt溶液），对膝关节进行局部注射治疗，通过大体评分、影像学观察、炎症因子检测以及病理学评估等探讨其针对RA的治疗效果。
结果: 在体外实验中，细胞内ROS水平及LPS诱导的巨噬细胞M1型极化，ZIF-8@Pt组与LPS组相比，差异有统计学意义（P<0.05）；在体内实验中，针对CIA大鼠血清及关节局部的炎症因子水平的检测，如白细胞介素-1β（interleukin-1β, IL-1β）、C-反应蛋白（C-reactive protein, CRP）、肿瘤坏死因子-α（tumor necrosis factor-α, TNF-α）、精氨酸酶-1（arginase-1, Arg-1），ZIF-8@Pt组与Control组相比，差异有统计学意义（P<0.05）。病理学评估表明，与Control组相比，ZIF-8@Pt可缓解关节局部乏氧，抑制血管新生、破骨活动以及巨噬细胞M1型极化（P<0.05）。
结论: ZIF-8@Pt仿酶制剂能够通过清除活性氧ROS而抑制巨噬细胞炎性极化进而改善RA炎性环境。同时，其可改善关节腔乏氧环境，抑制血管新生及骨破坏，对RA具有良好的治疗效果。
Keywords: Anti-inflammatory treatment; Nanomaterials; Nanozyme; Reactive oxygen species; Rheumatoid arthritis.
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