Division of Pediatric Nephrology, Department of Pediatrics, Rady Children's Hospital San Diego, University of California, San Diego, La Jolla, CA, USA.
Department of Nephrology and Rheumatology, Shanghai Children's Hospital, Shanghai Jiao Tong University, Shanghai, China.
J Cachexia Sarcopenia Muscle. 2021 Oct;12(5):1296-1311. doi: 10.1002/jcsm.12744. Epub 2021 Jun 30.
Ctns mice, a mouse model of infantile nephropathic cystinosis, exhibit hypermetabolism with adipose tissue browning and profound muscle wasting. Inflammatory cytokines such as interleukin (IL)-1 trigger inflammatory cascades and may be an important cause for cachexia. We employed genetic and pharmacological approaches to investigate the effects of IL-1 blockade in Ctns mice.
We generated Ctns Il1β mice, and we treated Ctns and wild-type control mice with IL-1 receptor antagonist, anakinra (2.5 mg/kg/day, IP) or saline as vehicle for 6 weeks. In each of these mouse lines, we characterized the cachexia phenotype consisting of anorexia, loss of weight, fat mass and lean mass, elevation of metabolic rate, and reduced in vivo muscle function (rotarod activity and grip strength). We quantitated energy homeostasis by measuring the protein content of uncoupling proteins (UCPs) and adenosine triphosphate in adipose tissue and skeletal muscle. We measured skeletal muscle fiber area and intramuscular fatty infiltration. We also studied expression of molecules regulating adipose tissue browning and muscle mass metabolism. Finally, we evaluated the impact of anakinra on the muscle transcriptome in Ctns mice.
Skeletal muscle expression of IL-1β was significantly elevated in Ctns mice relative to wild-type control mice. Cachexia was completely normalized in Ctns Il1β mice relative to Ctns mice. We showed that anakinra attenuated the cachexia phenotype in Ctns mice. Anakinra normalized UCPs and adenosine triphosphate content of adipose tissue and muscle in Ctns mice. Anakinra attenuated aberrant expression of beige adipose cell biomarkers (UCP-1, CD137, Tmem26, and Tbx1) and molecules implicated in adipocyte tissue browning (Cox2/Pgf2α, Tlr2, Myd88, and Traf6) in inguinal white adipose tissue in Ctns mice. Moreover, anakinra normalized gastrocnemius weight and fiber size and attenuated muscle fat infiltration in Ctns mice. This was accompanied by correction of the increased muscle wasting signalling pathways (increased protein content of ERK1/2, JNK, p38 MAPK, and nuclear factor-κB p65 and mRNA expression of Atrogin-1 and Myostatin) and the decreased myogenesis process (decreased mRNA expression of MyoD and Myogenin) in the gastrocnemius muscle of Ctns mice. Previously, we identified the top 20 differentially expressed skeletal muscle genes in Ctns mice by RNAseq. Aberrant expression of these 20 genes have been implicated in muscle wasting, increased energy expenditure, and lipolysis. We showed that anakinra attenuated 12 of those top 20 differentially expressed muscle genes in Ctns mice.
Anakinra may provide a targeted novel therapy for patients with infantile nephropathic cystinosis.
Ctns 小鼠，一种婴儿型遗传性胱氨酸病的小鼠模型，表现出代谢亢进，伴有脂肪组织褐变和严重的肌肉消耗。白细胞介素（IL）-1 等炎性细胞因子触发炎症级联反应，可能是恶病质的重要原因。我们采用遗传和药理学方法研究了 IL-1 阻断在 Ctns 小鼠中的作用。
我们生成了 Ctns Il1β 小鼠，并对 Ctns 和野生型对照小鼠进行了 6 周的 IL-1 受体拮抗剂（anakinra，2.5mg/kg/天，腹腔注射）或生理盐水处理。在这些小鼠品系中，我们描述了恶病质表型，包括食欲不振、体重减轻、体脂和瘦体重减少、代谢率升高以及体内肌肉功能降低（转棒活动和握力）。我们通过测量脂肪组织和骨骼肌中解偶联蛋白（UCPs）和三磷酸腺苷的蛋白含量来量化能量稳态。我们测量了骨骼肌纤维面积和肌内脂肪浸润。我们还研究了调节脂肪组织褐变和肌肉质量代谢的分子的表达。最后，我们评估了 anakinra 对 Ctns 小鼠肌肉转录组的影响。
与野生型对照小鼠相比，Ctns 小鼠的骨骼肌中 IL-1β 的表达显著升高。与 Ctns 小鼠相比，Ctns Il1β 小鼠的恶病质完全正常化。我们表明 anakinra 减轻了 Ctns 小鼠的恶病质表型。Anakinra 使 Ctns 小鼠的脂肪组织和肌肉中的 UCPs 和三磷酸腺苷含量正常化。Anakinra 减弱了 Ctns 小鼠腹股沟白色脂肪组织中米色脂肪细胞生物标志物（UCP-1、CD137、Tmem26 和 Tbx1）和与脂肪组织褐变相关分子（Cox2/Pgf2α、Tlr2、Myd88 和 Traf6）的异常表达。此外，anakinra 使 Ctns 小鼠的腓肠肌重量和纤维大小正常化，并减轻了肌肉脂肪浸润。这伴随着对增加的肌肉消耗信号通路（ERK1/2、JNK、p38 MAPK 和核因子-κB p65 的蛋白含量增加以及 Atrogin-1 和 Myostatin 的 mRNA 表达增加）和减少的肌肉发生过程（腓肠肌中 MyoD 和 Myogenin 的 mRNA 表达减少）的纠正。先前，我们通过 RNAseq 鉴定了 Ctns 小鼠中 20 个差异表达的骨骼肌基因。这些 20 个基因的异常表达与肌肉消耗、能量消耗增加和脂肪分解有关。我们表明，anakinra 减轻了 Ctns 小鼠中这 20 个差异表达肌肉基因中的 12 个。
Anakinra 可能为婴儿型遗传性胱氨酸病患者提供一种有针对性的新型治疗方法。
