背景：脓毒症仍然是世界范围内重症监护病房（ICU）的一种常见疾病。其发病机制以宿主对入侵病原体反应失调为特征，可以导致多种危及生命的器官功能障碍。在脓毒症中，肺是受影响最严重的器官之一，常常发展为急性肺损伤（acute lung injury, ALI）。由于缺乏有效的治疗方法，ALI可以进一步发展为急性呼吸窘迫综合征（acute respiratory distress syndrome, ARDS），因其高发病率和死亡率成为临床工作的难点。因此，开发一种具有抗炎特性的纳米药物可能是治疗ALI的一种很有前景的策略。辣椒素（Capsaicin, CAP）是一种在辣椒中发现的天然化合物，具有缓解疼痛和抗炎的特性。但由于辣椒素的疏水性，其在体内的应用受到了一定的限制。本研究中，我们开发了一种含有辣椒素和铁的纳米颗粒（Fe-CAP NPs），进一步探索了Fe-CAP NPs治疗ALI的相关机制。

方法：合成铁-辣椒素纳米酶，并对Fe-CAP NPs进行粒径分析、稳定性测试、紫外光谱、SEM检测及元素分析。RAW264.7细胞和骨髓源性巨噬细胞（Bone marrow-derived macrophage, BMDM）分为4组：CON(control)组、脂多糖（lipopolysaccharide，LPS）组、CAP+LPS组、Fe-CAP NPs+LPS组。采用免疫荧光、蛋白质免疫印迹实验（Western Blot）和酶联免疫吸附法（ELISA）检测诱导型一氧化氮合酶（iNOS）、转化生长因子-β（TGF-β）、肿瘤坏死因子-α（TNF-α）和巨噬细胞表型标志物CD86、CD206的表达。采用荧光微珠、Transwell和ROS试剂盒检测BMDM的吞噬、迁移和清除ROS的能力。Western Blot检测BMDM中JAK2/STAT3信号通路及凋亡蛋白的表达。将C57小鼠分为对照组、LPS组、CAP+LPS组、Fe-CAP NPs+LPS组。Western Blot检测小鼠肺组织中白细胞介素-6（IL-6）、iNOS、CD86和CD206的表达。ELISA检测小鼠肺泡灌洗液（BALF）和血清中IL-6和TNF-α的表达。免疫组化检测肺组织中IL-6和TNF-α的表达。TUNEL试剂盒检测肺组织凋亡。采用伊文思蓝外渗、肺组织病理学评分和干湿重比（W/D）评估肺毛细血管通透性。对小鼠血液及主要脏器（心、肝、脾、肺、肾）进行Fe-CAP NPs的毒性检测。

结果：铁-辣椒素纳米酶具有良好的稳定性和形貌。细胞实验中，LPS组TNF-α、iNOS、CD86、P-JAK2、P-STAT3、Bax、Cleaved-caspase-3表达升高。在Fe-CAP NPs+LPS组，它们的表达明显降低。TGF-β、CD206和Bcl-2的表达呈相反的趋势。Fe-CAP NPs减少LPS刺激的BMDM的吞噬、迁移和ROS。动物实验中，LPS组小鼠肺组织和肺泡灌洗液中IL-6和TNF-α表达增加，Fe-CAP NPs预处理降低它们的表达。LPS组肺组织CD86表达升高，Fe-CAP预处理组肺组织CD86表达降低，CD206的表达相反。Fe-CAP可显著改善小鼠肺EB渗漏，改善肺组织病理学，降低W/D重量比，减少肺组织细胞凋亡。在研究这些生物活性时，纳米颗粒显示出无细胞毒性。

结论：Fe-CAP NPs可通过调节巨噬细胞的极化和功能，减少促炎因子的表达，增加抗炎因子的表达，降低ROS水平和细胞凋亡来缓解脓毒症诱导的急性肺损伤。

Background: Sepsis remains to be a prevalent condition in intensive care units (icus) worldwide. It is characterized by dysfunctional host response to invading pathogens, leading to a variety of life-threatening organ dysfunction. In sepsis, the lungs are one of the most severely affected organs, often developing into acute lung injury (ALI). Due to the lack of effective treatment, ALI can further develop into acute respiratory distress syndrome (ARDS), which is difficult in clinical work due to its high morbidity and mortality. Therefore, developing a nanomedicine with anti-inflammatory properties may be a promising strategy for treating ALI. Capsaicin (CAP), a natural compound found in chili peppers known for its pain-relieving and anti-inflammatory effects. However, due to the hydrophobicity of capsaicin, its application in vivo has been limited. In this study, we developed a nanoparticle containing capsaicin and iron (Fe-CAP NPs) to further explore the mechanism related to the treatment of ALI by Fe-CAP NPs. Methods: Fe-CAP NPs was synthesized and analyzed by particle size, stability, UV spectrum, SEM and elemental analysis. RAW264.7 cells and Bone marrow-derived macrophages (BMDM) were divided into four groups: CON(control) group, LPS group, CAP+LPS group, and Fe-CAP NPs+LPS group. The expressions of inducible nitric oxide synthase (iNOS), transforming growth factor-β (TGF-β), tumor necrosis factor-α (TNF-α) and macrophage phenotypic markers CD86 and CD206 were detected by immunofluorescence, Western Blot and enzyme-linked immunosorbent assay (ELISA). The phagocytic, migratory, and ROS-clearing ability of BMDM were evaluated using fluorescent microbeads, Transwell assay and ROS detection kits. The expression of JAK2/STAT3 signaling pathway and apoptosis protein in BMDM was detected by Western Blot. C57 mice were divided into control group, LPS group, CAP+LPS group, Fe-CAP NPs+LPS group. The expressions of interleukin-6 (IL-6), iNOS, CD86 and CD206 in mouse lung tissues were detected by Western Blot. The expression of IL-6 and TNF-α in alveolar lavage fluid (BALF) and serum were detected by ELISA. The expression of IL-6 and TNF-α in lung tissue was detected by immunohistochemistry. Lung apoptosis was detected by TUNEL kit. Evans blue exosmosis, lung histopathology score and W/D were used to evaluate pulmonary capillary permeability. Fe-CAP NPs toxicity was detected in blood and major organs (heart, liver, spleen, lung and kidney) of mice. Results: Fe-CAP NPs has good stability and morphology. In cell experiments, the expression of TNF-α, iNOS, CD86, P-JAK2, P-STAT3, Bax, Cleaved caspase-3 were increased in the LPS group. In Fe-CAP NPs+LPS group, their expression were significantly decreased. The expression of TGF-β, CD206 and Bcl-2 showed the opposite trend. Fe-CAP NPs reduced phagocytosis, migration, and ROS of LPS-stimulated BMDM. In animal experiments, IL-6 and TNF-α expression increased in lung tissue and BALF in LPS group, while Fe-CAP NPs pretreatment decreased their expression. The expression of CD86 in lung tissues of LPS group was increased, the expression of CD86 in Fe-CAP+LPS group was decreased, and the expression of CD206 was reversed. Fe-CAP could significantly improve EB leakage, lung histopathology, reduce W/D weight ratio and lung cell apoptosis in mice. The nanoparticles showed non-cytotoxicity, when studying these biological activities. Conclusion: Fe-CAP NPs could alleviate sepsis-induced acute lung injury by regulating the polarization and function of macrophages, inhibiting the expression of proinflammatory factors, increasing the expression of anti-inflammatory factors, and reducing ROS levels and cell apoptosis.