Chitinase 3-like-1 contributes to acetaminophen-induced liver injury by promoting hepatic platelet recruitment.
Chitinase 3-like-1 contributes to acetaminophen-induced liver injury by promoting hepatic platelet recruitment.
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作者：
Shan Z;Li L;Atkins CL;Wang M;Wen Y;Jeong J;Moreno NF;Feng D;Gui X;Zhang N;Lee CG;Elias JA;Lee WM;Gao B;Lam FW;An Z;Ju C
肝血小板聚集导致对乙酰氨基酚（APAP）诱导的肝损伤（AILI）。然而，对于血小板募集到肝脏所涉及的分子途径以及靶向这些途径是否能够减轻AILI，我们知之甚少。
在给雄性小鼠腹腔注射210mg/kg、雌性小鼠腹腔注射325mg/kg的APAP之前，小鼠禁食过夜。在小鼠以及对乙酰氨基酚过量的患者中测定了黏附于库普弗细胞的血小板。在治疗环境中确定了α - 几丁质酶3样 - 1（α - Chi3l1）对减轻AILI的影响，并对肝损伤进行了分析。
本研究揭示了Chi3l1在AILI期间肝血小板募集中的关键作用。在对乙酰氨基酚过量的患者和小鼠中观察到肝脏中Chi3l1和血小板增加。与野生型（WT）小鼠相比，Chil1 - / - 小鼠发生的AILI减轻，肝血小板聚集显著减少。机制研究表明，Chi3l1通过巨噬细胞上的CD44发出信号，诱导平足蛋白表达，平足蛋白通过C型凝集素样受体2介导血小板募集。此外，对Cd44 - / - 小鼠进行APAP处理后，其肝血小板数量和肝损伤比WT小鼠低得多，这种表型与Chil1 - / - 小鼠相似。重组Chi3l1能够恢复Chil1 - / - 小鼠的肝血小板聚集和AILI，但不能恢复Cd44 - / - 小鼠的。重要的是，我们制备了抗 - Chi3l1单克隆抗体，并证明它们能够有效抑制肝血小板聚集和AILI。
我们揭示了Chi3l1/CD44轴是介导APAP诱导的肝血小板募集和组织损伤的关键途径。我们证明了靶向Chi3l1治疗AILI的可行性和潜力。
ZS获得了国家自然科学基金（32071129）的资助。FWL获得了美国国立卫生研究院（GM123261）的资助。ALFSG获得了美国国立糖尿病、消化和肾脏疾病研究所（DK 058369）的资助。ZA获得了得克萨斯癌症预防与研究研究所（RP150551和RP190561）以及韦尔奇基金会（AU - 0042–20030616）的资助。CJ获得了美国国立卫生研究院（DK122708，DK109574，DK121330和DK122796）的资助以及得克萨斯大学系统转化之星奖的支持。这项工作的部分得到了迈克尔·E·德巴基退伍军人医疗中心的资源和设施使用的支持，以及美国退伍军人事务部I01 BX002551（设备、人员、物资）的资助。内容不代表美国退伍军人事务部或美国政府的观点。
对乙酰氨基酚，在美国以外也被称为扑热息痛，是一种常用的止痛药，在美国每周有超过5000万人服用这种药物。虽然扑热息痛在标准剂量下是安全的，但过量服用会导致急性肝衰竭，这导致美国每年有30000名患者被送进急诊室。对于过量服用只有一种批准的解毒剂，如果其使用延迟超过几个小时，效果会显著降低。这促使人们研究确定新的药物靶点，从而可能产生更多的治疗选择。
对乙酰氨基酚过量会引发凝血和炎症，导致肝损伤。它还会导致血液中循环的血小板细胞减少，这在小鼠和人类中都有观察到。在小鼠中，这是因为血小板在肝脏中聚集。去除这些多余的细胞似乎可以降低对乙酰氨基酚造成的损伤严重程度，但目前仍不清楚该药物是如何触发它们在肝脏中聚集的。2018年，研究人员表明一种名为Chi3l1的蛋白质在另一种形式的肝损伤中起着重要作用。Shan等人——包括许多参与2018年研究的研究人员——已经研究了该蛋白质是否也会导致肝脏中的对乙酰氨基酚损伤。
Shan等人表明，缺乏编码Chi3l1的基因的小鼠在对乙酰氨基酚过量后肝损伤较轻，肝脏中的血小板较少。他们还发现，因对乙酰氨基酚导致急性肝衰竭的人类患者肝脏中Chi3l1水平较高，血小板显著聚集。为了测试是否可以预防损伤，Shan等人在给小鼠过量服用对乙酰氨基酚后，使用抗体中和Chi3l1。这减少了肝脏中的血小板聚集以及相关损伤。
这些发现表明，靶向Chi3l1可能是预防对乙酰氨基酚过量导致肝损伤的有效策略。进一步的研究可能有助于开发对乙酰氨基酚诱导的肝损伤以及也许其他肝脏疾病的新治疗方法。
Hepatic platelet accumulation contributes to acetaminophen (APAP)-induced liver injury (AILI). However, little is known about the molecular pathways involved in platelet recruitment to the liver and whether targeting such pathways could attenuate AILI. Mice were fasted overnight before intraperitoneally (i.p.) injected with APAP at a dose of 210 mg/kg for male mice and 325 mg/kg for female mice. Platelets adherent to Kupffer cells were determined in both mice and patients overdosed with APAP. The impact of α-chitinase 3-like-1 (α-Chi3l1) on alleviation of AILI was determined in a therapeutic setting, and liver injury was analyzed. The present study unveiled a critical role of Chi3l1 in hepatic platelet recruitment during AILI. Increased Chi3l1 and platelets in the liver were observed in patients and mice overdosed with APAP. Compared to wild-type (WT) mice, Chil1-/- mice developed attenuated AILI with markedly reduced hepatic platelet accumulation. Mechanistic studies revealed that Chi3l1 signaled through CD44 on macrophages to induce podoplanin expression, which mediated platelet recruitment through C-type lectin-like receptor 2. Moreover, APAP treatment of Cd44-/- mice resulted in much lower numbers of hepatic platelets and liver injury than WT mice, a phenotype similar to that in Chil1-/- mice. Recombinant Chi3l1 could restore hepatic platelet accumulation and AILI in Chil1-/- mice, but not in Cd44-/- mice. Importantly, we generated anti-Chi3l1 monoclonal antibodies and demonstrated that they could effectively inhibit hepatic platelet accumulation and AILI. We uncovered the Chi3l1/CD44 axis as a critical pathway mediating APAP-induced hepatic platelet recruitment and tissue injury. We demonstrated the feasibility and potential of targeting Chi3l1 to treat AILI. ZS received funding from NSFC (32071129). FWL received funding from NIH (GM123261). ALFSG received funding from NIDDK (DK 058369). ZA received funding from CPRIT (RP150551 and RP190561) and the Welch Foundation (AU-0042–20030616). CJ received funding from NIH (DK122708, DK109574, DK121330, and DK122796) and support from a University of Texas System Translational STARs award. Portions of this work were supported with resources and the use of facilities of the Michael E. DeBakey VA Medical Center and funding from Department of Veterans Affairs I01 BX002551 (Equipment, Personnel, Supplies). The contents do not represent the views of the US Department of Veterans Affairs or the US Government. Acetaminophen, also called paracetamol outside the United States, is a commonly used painkiller, with over 50 million people in the United States taking the drug weekly. While paracetamol is safe at standard doses, overdose can cause acute liver failure, which leads to 30,000 patients being admitted to emergency care in the United States each year. There is only one approved antidote to overdoses, which becomes significantly less effective if its application is delayed by more than a few hours. This has incentivized research into identify new drug targets that could lead to additional treatment options. Acetaminophen overdose triggers blood clotting and inflammation, contributing to liver injury. It also causes a decrease in cells called platelets circulating in the blood, which has been observed in both mice and humans. In mice, this occurs because platelets accumulate in the liver. Removing these excess cells appears to reduce the severity of the damage caused by acetaminophen, but it remains unclear how the drug triggers their accumulation in the liver. In 2018, researchers showed that a protein called Chi3l1 plays an important role in another form of liver damage. Shan et al. – including many of the researchers involved in the 2018 study – have examined whether the protein also contributes to acetaminophen damage in the liver. Shan et al. showed that mice lacking the gene that codes for Chi3l1 developed less severe liver injury and had fewer platelets in the liver following acetaminophen overdose. They also found that human patients with acute liver failure due to acetaminophen had high levels of Chi3l1 and significant accumulation of platelets in the liver. To test whether damage could be prevented, Shan et al. used antibodies to neutralize Chi3l1 in mice after giving them an acetaminophen overdose. This reduced platelet accumulation in the liver and the associated damage. These findings suggest that targeting Chi3l1 may be an effective strategy to prevent liver damage caused by acetaminophen overdose. Further research could help develop new treatments for acetaminophen-induced liver injury and perhaps other liver conditions.