Stilkerich Anna, Schicht Gerda, Seidemann Lena, Hänsel René, Friebel Adrian, Hoehme Stefan, Seehofer Daniel, Damm Georg
Department of Hepatobiliary Surgery and Visceral Transplantation, University Hospital, Leipzig University, 04103 Leipzig, Germany.
Saxonian Incubator for Clinical Translation (SIKT), Leipzig University, 04103 Leipzig, Germany.
Cells. 2025 Mar 18;14(6):449. doi: 10.3390/cells14060449.
Metabolic-dysfunction-associated steatotic liver disease (MASLD) is a prevalent liver condition with potential progression to cirrhosis and impaired regeneration post-resection. A key mechanism underlying lipotoxicity is endoplasmic reticulum (ER) stress, particularly the activation of the unfolded protein response (UPR). This study investigates the interplay between lipid accumulation, endoplasmic reticulum (ER) stress, and cellular outcomes, focusing on the balance between autophagy and apoptosis. We cultured primary human hepatocytes (PHH) in a free fatty acid (FFA)-enriched medium for 120 h, assessing lipid accumulation, metabolism, and the expression of selected UPR markers. Additionally, we investigated the effects of lipid load on cell activity and growth in proliferating HepG2 cells. We observed that FFA uptake consistently induced ER stress, shifting cellular responses toward apoptosis under high lipid loads. Donor-specific differences were evident, particularly in lipid storage, excretion, and sensitivity to lipotoxicity. Some donors exhibited limited triglyceride (TAG) storage and excretion, leading to an excess of FFA whose metabolic fate remains unclear. Proliferation was more sensitive to lipid accumulation than overall cell activity, with even low FFA concentrations impairing growth, highlighting the vulnerability of regenerative processes to steatosis. The study elucidates how ER stress pathways, such as PERK-CHOP and IRE1α-JNK, are differentially activated in response to lipid overload, tipping the balance toward apoptosis in severe cases. The limited activation of repair mechanisms, such as autophagy, further emphasizes the critical role of ER stress in determining hepatocyte fate. The donor-dependent variability highlights the need for personalized strategies to mitigate lipotoxic effects and enhance liver regeneration in steatosis-related conditions.
代谢功能障碍相关脂肪性肝病（MASLD）是一种常见的肝脏疾病，有发展为肝硬化以及肝切除术后再生受损的潜在风险。脂毒性的一个关键机制是内质网（ER）应激，尤其是未折叠蛋白反应（UPR）的激活。本研究调查了脂质蓄积、内质网应激与细胞结局之间的相互作用，重点关注自噬与凋亡之间的平衡。我们在富含游离脂肪酸（FFA）的培养基中培养原代人肝细胞（PHH）120小时，评估脂质蓄积、代谢以及选定的UPR标志物的表达。此外，我们研究了脂质负荷对增殖的HepG2细胞的细胞活性和生长的影响。我们观察到FFA摄取持续诱导内质网应激，在高脂质负荷下使细胞反应转向凋亡。供体特异性差异明显，尤其是在脂质储存、排泄以及对脂毒性的敏感性方面。一些供体的甘油三酯（TAG）储存和排泄有限，导致过量的FFA，其代谢命运尚不清楚。增殖对脂质蓄积比总体细胞活性更敏感，即使是低浓度的FFA也会损害生长，这突出了再生过程对脂肪变性的脆弱性。该研究阐明了内质网应激途径，如PERK-CHOP和IRE1α-JNK，如何在脂质过载时被差异激活，在严重情况下使平衡向凋亡倾斜。自噬等修复机制的有限激活进一步强调了内质网应激在决定肝细胞命运中的关键作用。供体依赖性变异性突出了需要个性化策略来减轻脂毒性作用并增强脂肪变性相关病症中的肝脏再生。
