DataSheet_1_Interleukin-10 disrupts liver repair in acetaminophen-induced acute liver failure.pdf

IntroductionSystemic levels of the anti-inflammatory cytokine interleukin 10 (IL-10) are highest in acetaminophen (APAP)-induced acute liver failure (ALF) patients with the poorest prognosis. The mechanistic basis for this counterintuitive finding is not known, as induction of IL-10 is hypothesized to temper the pathological effects of immune cell activation. Aberrant production of IL-10 after severe liver injury could conceivably interfere with the beneficial, pro-reparative actions of immune cells, such as monocytes.
MethodsTo test this possibility, we determined whether IL-10 levels are dysregulated in mice with APAP-induced ALF and further evaluated whether aberrant production of IL-10 prevents monocyte recruitment and/or the resolution of necrotic lesions by these cells.
ResultsOur studies demonstrate that in mice challenged with 300 mg/kg acetaminophen (APAP), a hepatotoxic dose of APAP that fails to produce ALF (i.e., APAP-induced acute liver injury; AALI), Ly6Chi monocytes were recruited to the liver and infiltrated the necrotic lesions by 48 hours coincident with the clearance of dead cell debris. At 72 hours, IL-10 was upregulated, culminating in the resolution of hepatic inflammation. By contrast, in mice treated with 600 mg/kg APAP, a dose that produces clinical features of ALF (i.e., APAP-induced ALF; AALF), IL-10 levels were markedly elevated by 24 hours. Early induction of IL-10 was associated with a reduction in the hepatic numbers of Ly6Chi monocytes resulting in the persistence of dead cell debris. Inhibition of IL-10 in AALF mice, beginning at 24 hours after APAP treatment, increased the hepatic numbers of monocytes which coincided with a reduction in the necrotic area. Moreover, pharmacologic elevation of systemic IL-10 levels in AALI mice reduced hepatic myeloid cell numbers and increased the area of necrosis.
DiscussionCollectively, these results indicate that during ALF, aberrant production of IL-10 disrupts the hepatic recruitment of monocytes, which prevents the clearance of dead cell debris. These are the first studies to document a mechanistic basis for the link between high IL-10 levels and poor outcome in patients with ALF.

引言
在对乙酰氨基酚（acetaminophen, APAP）诱导的急性肝衰竭（acute liver failure, ALF）患者中，全身抗炎细胞因子白细胞介素10（interleukin 10, IL-10）水平在预后最差的人群中最高。这一反直觉发现的机制尚不清楚，因为学界普遍认为IL-10的诱导可缓解免疫细胞活化带来的病理损伤。严重肝损伤后IL-10的异常产生，可能会干扰单核细胞等免疫细胞发挥有益的促修复功能。

方法
为验证这一假说，本研究首先检测了APAP诱导ALF小鼠体内IL-10水平是否存在失调，并进一步评估了IL-10异常产生是否会阻碍单核细胞招募，以及这些细胞对坏死病灶的清除作用。

结果
本研究证实，给予300mg/kg对乙酰氨基酚（该剂量为肝毒性剂量，但不会引发ALF，即APAP诱导的急性肝损伤（APAP-induced acute liver injury, AALI））的小鼠中，Ly6C高表达单核细胞于造模后48小时招募至肝脏并浸润坏死病灶，此时恰好伴随死细胞碎片的清除。造模后72小时，IL-10表达上调，最终实现肝脏炎症的消退。
与之相反，给予600mg/kg对乙酰氨基酚（该剂量可引发ALF的临床特征，即APAP诱导的急性肝衰竭（APAP-induced ALF, AALF））的小鼠中，IL-10水平在造模后24小时即显著升高。IL-10的早期诱导与肝脏内Ly6C高表达单核细胞数量减少相关，进而导致死细胞碎片持续存留。
在AALF小鼠中，于APAP给药后24小时开始抑制IL-10，可增加肝脏内单核细胞数量，同时伴随坏死区域缩小。此外，对AALI小鼠进行系统性IL-10的药物升高处理，会减少肝脏髓系细胞数量并扩大坏死区域。

讨论
综合上述结果，本研究表明在ALF进程中，IL-10的异常产生会破坏单核细胞的肝脏招募，从而阻碍死细胞碎片的清除。本研究首次阐明了ALF患者体内高IL-10水平与不良预后之间关联的机制基础。